Journal articles: 'Diakinesis'

1

Reed, Kent M., Jack W. Sites Jr., and Ira F. Greenbaum. "Chromosomal synapsis and the meiotic process in male mesquite lizards, Sceloporus grammicus complex." Genome 35, no. 3 (1992): 398–408. http://dx.doi.org/10.1139/g92-060.

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Meiosis in males of the F5 cytotype of Sceloporus grammicus was examined through the analysis of synaptonemal complexes (SCs), diakinetic (metaphase I) nuclei, and secondary spermatocytes (metaphase II configurations). These data allowed the establishment of criteria for substaging of zygonema and pachynema, morphological characterization of the SC complement, and comparison of the orientation and segregation of the autosomes and sex chromosomes. The analysis of nuclei from all stages of meiotic prophase I (leptonema through diakinesis) provided a useful means of partitioning the temporal sequence of early meiotic events. Three substages of zygonema (Z1–Z3) were established, based on the extent of synapsis of the microchromosomal and macrochromosomal elements. Synaptic initiation of the autosomes and sex chromosomes was synchronous. Two patterns of macrochromosomal synapsis were observed. Whereas synapsis of the biarmed elements was biterminal (i.e., progressing from both ends of the homologs), synapsis of the acrocentric elements was uniterminal involving only the distal (noncentromeric) ends of the homologs. Unique sex-chromosomal characteristics were not observed in S. grammicus and, therefore, the substaging of pachynema was based on subjective criteria. Examination of diakinesis – metaphase I and metaphase II configurations indicated low levels of diakinetic irregularities with balanced segregation of the autosomal bivalents and the sex-chromosomal trivalent.Key words: Sceloporus grammicus, meiosis, synaptonemal complex, substaging.

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2

Wolf, Paul G., Pamela S. Soltis, and Douglas E. Soltis. "Tetrasomic inheritance and chromosome pairing behaviour in the naturally occurring autotetraploid Heuchera grossulariifolia (Saxifragaceae)." Genome 32, no. 4 (1989): 655–59. http://dx.doi.org/10.1139/g89-494.

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Inheritance patterns at four allozyme loci and chromosome pairing behaviour at diakinesis were examined in the naturally occurring autotetraploid Heuchera grossulariifolia. Segregation patterns for Tpi, Pgi, Pgm-2, and Lap deviated significantly from all possible disomic models. All patterns were consistent with tetrasomic inheritance of these marker loci. No chromatid segregation was detected electrophoretically. Meiotic chromosome configurations at diakinesis in 45 cells were compared with a previously published model to test for autopolyploid-like chromosome pairing. Using the observed chiasma frequencies, the frequency of quadrivalents was consistent with the expectations for an autotetraploid. We suggest that the low frequency of quadrivalents at diakinesis in Heuchera grossulariifolia is due to small chromosome size, which results in a low chiasma frequency.Key words: autopolyploidy, tetrasomic inheritance, chromosome pairing, isozyme genetics, Heuchera.

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3

Maguire, Marjorie P., and Janet Day Jackson. "Two well-known mutants of chiasma maintenance function in maize are allelic." Genome 41, no. 3 (1998): 417–21. http://dx.doi.org/10.1139/g98-029.

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By a series of traditional crosses, allelism has been tested for two maize recessive mutants of independent origin, dy1 and dsy1, both called desynaptic. These mutants both display loss of chiasmate association during diakinesis (late prophase I) but at differing frequencies. This chiasma loss happens before nucleolar loss and nuclear membrane system breakdown. That crossovers have occurred to establish the chiasmata in the first place has been documented by diakinesis-stage separation of heterozygous heterochromatic regions in univalents formed by bivalent-association breakdown. In the present work, the two mutants have been found to be allelic by the outcome of traditional crosses that produced variant plants which were heterozygous for the two alleles. These plants express a unique phenotype at diakinesis, but are essentially normal at pachytene, metaphase I, anaphase I, and later stages of meiosis.Key words: chiasma, crossover, complementation.

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Sikiru, Omokanye Babatunde. "Chromosomes Behavior at Meiosis in Chlorophytum stenopetalum Bak at Pachytene, Diakinesis and Diplotene." Journal of Applied Sciences and Environmental Management 25, no. 4 (2021): 493–96. http://dx.doi.org/10.4314/jasem.v25i4.

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Meiotic prophase is classically subdivided into five stages: leptotene, zygotene, pachytene, diplotene, and diakinesis. The objective of this paper is to evaluate the behaviours of Chromosomes in Chlorophytum stenopetalum Bak.at pachytene /diakinesis and metaphase. The flower buds at right age were harvested, fixed in Cornoy’s solution (3 part of absolute alcohol and 1 part of acetic alcohol) and preserved in a refrigerator at -4°𝐶 for at least thirty minutes. The flower buds were then hydrolyzed in 10% HCl for 3-5 minutes. Prepared slides were viewed using an Armscope microscope equipped with digital automatic camera. At diakinesis seven bivalents (7 II) were predominantly observed (74.2%). Chromosomal stickiness is quite evidence. In addition, cross configuration and its resultant, ring formation at metaphase indicate the presence of translocation heterozgosity in the chromosomes of the species investigated. These abnormalities are likely to affect microsporogenesis and pollen viability.

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Diluraj, Sangeetha. "Tertiary trisomics in 2n = 12 Coix taxon." Annals of Plant Sciences 7, no. 4 (2018): 2198. http://dx.doi.org/10.21746/aps.2018.7.4.21.

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Tertiary trisomics have been isolated from the domesticated outcrossed population of a comparatively new taxon of Coix with 2n = 12 chromosome number and also from the selfed progenies of the chromosomal variants ranging from 2n=11 to 2n=13. Cytological analysis of these trisomics indicated that different chromosomal associations forming a trivalent, pentavalent and univalent were frequent at diakinesis. Disomics (2n = 12) and their monosomics (2n-1; 2n = 11) showing interchanged quadrivalents at diakinesis were observed to be the main sources of these tertiary trisomics.

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6

Cheng, B. F., W. K. Heneen, and B. Y. Chen. "Meiotic studies on a Brassica campestris–alboglabra monosomic addition line and derived B. campestris primary trisomics." Genome 37, no. 4 (1994): 584–89. http://dx.doi.org/10.1139/g94-083.

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Diakinesis chromosomes were studied in pollen mother cells of Brassica campestris (2n = 20, genome AA), B. alboglabra (2n = 18, genome CC), a B. campestris–alboglabra monosomic addition line (AA + 1 chromosome from the C genome), and four derived B. campestris primary trisomics. The nucleolar chromosomes of B. campestris were distinguishable by their morphology at diakinesis. The alien C-genome chromosome in the addition line paired preferentially with the nucleolar chromosome of the A genome. Very rarely, it paired with another pair of the A genome. Thus, it was concluded that the alien C-genome chromosome of the addition line is primarily homoeologous to the nucleolar chromosome and secondarily to another chromosome of the A genome. Three of the four derived B. campestris trisomic plants were identified as B campestris nucleolar trisomics. Trisomy in the fourth plant involved another chromosome. The cytological mechanism underlying the origin of trisomics in the addition line and chromosome homoeology relationships between B. campestris and B. alboglabra are envisaged.Key words: Brassica campestris–alboglabra addition line, Brassica campestris trisomics, diakinesis, intergenomic chromosome homoeology.

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7

HULTÉN, MAJ. "Chiasma distribution at diakinesis in the normal human male." Hereditas 76, no. 1 (2009): 55–78. http://dx.doi.org/10.1111/j.1601-5223.1974.tb01177.x.

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8

SB, Omokanye. "Meiotic Chromosomes Behavious in Chlorophytum stenopetalum Bak." Research International Journal of Plant Science and Ecology 01, no. 01 (2020): 001–3. http://dx.doi.org/10.37179/rijpse.000001.

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Chromosomes behavior at meiosis in Chlorophytum stenopetalum Bak. was investigated especially at pachytene /diakinesis and metaphase. The 􀏐lower buds at right age were harvested, 􀏐ixed in Cornoy’s solution (3 part of absolute alcohol and 1 part of acetic alcohol) and preserved in a refrigerator at -4 for at least thirty minutes. The 􀏐lower buds were then hydrolyzed in 10% HCl for 3-5 minutes. Prepared slides were viewed using an Armscope microscope equipped with digital automatic camera. At diakinesis seven bivalents (7 II) were predominantly observed (74.2%). Chromosomal stickiness is quite evidence. In addition, cross con􀏐iguration and its resultant, ring formation at metaphase indicate the presence of translocation heterozgosity in the chromosomes of the species investigated. These abnormalities are likely to affect microsporogenesis and pollen viability.

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9

Wauben-Penris, P. J. J., G. P. J. M. van Meel, and P. de Boer. "Spermatogenic delay and increased chiasma frequency in T70H/+ male mice with hydroxyurea–Trenimon limited spermatocyte populations." Canadian Journal of Genetics and Cytology 27, no. 2 (1985): 192–99. http://dx.doi.org/10.1139/g85-029.

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T(1;13)70H/+ male mice were treated with hydroxyurea (HU) and Trenimon (T). This karyotype offers excellent possibilities for estimating number and position of chiasmata and segregation in meiotic anaphase I. By their cell-killing action during spermatogenesis, HU and T produce large gaps in the spermatogenic line. The surviving population between the gaps was analysed at diakinesis – metaphase I and metaphase II. We found by autoradiography a considerable retardation of the development from resting primary spermatocytes (RPS) to metaphase I and II as compared to untreated T70H/+ males. Furthermore we found increased chiasma frequencies in diakinesis – metaphase I (MI) and reduced nondisjunction frequencies at anaphse I as a result of the treatments applied. The latter effect could not be explained by the increased chiasma frequency.Key words: translocation, spermatogenesis, chiasmata, segregation, mouse, hydroxyurea.

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10

Maguire, M. P., R. W. Riess, and A. M. Paredes. "Evidence from a maize desynaptic mutant points to a probable role of synaptonemal complex central region components in provision for subsequent chiasma maintenance." Genome 36, no. 5 (1993): 797–807. http://dx.doi.org/10.1139/g93-105.

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Homozygotes for the dsy1 desynaptic mutant of maize show massive failure of chiasma maintenance during diplotene and diakinesis. Although some chiasmata persist until anaphase I in most microsporocytes expressing this mutant, homozygotes are completely or nearly completely sterile, owing apparently to disjunctive irregularities. Pachytene synaptic errors and some synaptic failure also are found, but recombination nodules are common in homologously synapsed regions, and equational separation of a heterozygous knob into univalents or open arms at diakinesis clearly demonstrates that chiasma failure occurs following crossing-over. A wider than normal synaptonemal complex central region and uniform apparent weakness of central region cross connections to spreading procedures strongly suggest the presence of a genetic lesion in a synaptonemal complex central region component. The dsy1 mutant may provide an especially important source of material for molecular studies on the nature of chiasma maintenance mechanism.Key words: chiasma maintenance, synaptonemal complex, meiotic mutant.

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11

Rao, Y. Saideswara, Melak H. Mengesha, and S. Appa Rao. "Cytomorphological studies of a spontaneous triploid in Pennisetum hohenackeri Hochst. ex Steud." Genome 32, no. 3 (1989): 404–7. http://dx.doi.org/10.1139/g89-462.

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During studies on the genomic relationships of the wild species of the genus Pennisetum, one spontaneous triploid (3x = 27) plant was identified among the diploid cytotypes (2n = 18) of Pennisetum hohenackeri Hochst. ex Steud. The triploid plant resembled the diploid in most morphological characters, except for the reduced number of spikelets. Chromosome associations of 9 II + 9 I were observed at diakinesis and metaphase I. The bivalents divided normally, while the univalents lagged and formed a separate nucleus, which was included in one of the daughter cells. On the basis of these studies, this plant was considered to be an allotriploid and might have originated as a spontaneous hybrid between diploid P. hohenackeri and an unknown tetraploid (amphidiploid) taxon with one of its genomes homologous to that of diploid P. hohenackeri. The possible donor of this genome could be P. orientale, which is a tetraploid with a basic chromosome number of x = 9.Key words: allotriploid, meiosis, diakinesis, univalents, micronuclei, laggards.

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12

Mabuchi, T. "Nucleolus organization and meiotic behaviour of B chromosomes in Hepatica nobilis." Genome 34, no. 6 (1991): 853–59. http://dx.doi.org/10.1139/g91-132.

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The C-banding karyotype of Hepatica nobilis indicates the A chromosome complement and B chromosomes (Bs) to be banded in the terminal regions. The A chromosomes (As) of this species comprise mainly euchromatin (89.7%) and a small amount of heterochromatin (10.3%). Bs of H. nobilis have terminal centromeres at one end and possess small satellites at the other end. Bs cause an increase in the number of nucleoli per cell, with a decrease in the size of each nucleolus. During meiosis, Bs associate as bivalents and multivalents up to pentavalents. These associate loosely with the short arm of satellited chromosome 7 (end to end association) at diakinesis in some pollen mother cells. Bivalent or trivalent Bs associate with a nucleolus at diakinesis. B chromosomes of H. nobilis thus appear to contain nucleolus organizing regions and may have originated from the satellited chromosome 7 and other members of As.Key words: Hepatica, satellited B, end to end association, origin, nucleolus organizing regions.

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13

Sybenga, J. "Preferential pairing estimates from multivalent frequencies in tetraploids." Genome 37, no. 6 (1994): 1045–55. http://dx.doi.org/10.1139/g94-149.

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Mathematical models are presented for estimating preferential pairing and chiasma parameters in amphidiploids and autotetraploids on the basis of diakinesis or metaphase I configuration frequencies and are compared with other approaches of estimating affinity. With a preferential pairing factor p, estimated from quadrivalent and trivalent frequencies, and estimated chiasmate association factors for the two arms in quadrivalents (a(qu) and b(qu) for arms A and B, respectively) and in bivalents (a(bi) and b(bi)) a perfect fit between observed and predicted configuration frequencies can often be obtained in amphidiploids of several plant species, including Solanaceae and Gramineae. Since several proven autotetraploids give very similar apparent preferential pairing estimates, the biological significance of such parameters as preferential pairing and affinity factors is considered limited. The same is true for pairing parameters estimated by optimizing fit of configuration frequencies expected on the basis of theoretical models to observed data.Key words: amphidiploid, diakinesis, metaphase, meiosis, model, preferential pairing, tetraploid.

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14

Golczyk, Hieronim, Krystyna Musiał, Uwe Rauwolf, Jörg Meurer, Reinhold G. Herrmann, and Stephan Greiner. "Meiotic events in Oenothera — a non-standard pattern of chromosome behaviour." Genome 51, no. 11 (2008): 952–58. http://dx.doi.org/10.1139/g08-081.

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The genus Oenothera shows an intriguing extent of permanent translocation heterozygosity. Reciprocal translocations of chromosome arms in species or populations result in various kinds of chromosome multivalents in diakinesis. Early meiotic events conditioning such chromosome behaviour are poorly understood. We found a surprising uniformity of the leptotene–diplotene period, regardless of the chromosome configuration at diakinesis (ring of 14, 7 bivalents, mixture of bivalents and multivalents). It appears that the earliest chromosome interactions at Oenothera meiosis are untypical, since they involve pericentromeric regions. During early leptotene, proximal chromosome parts cluster and form a highly polarized Rabl configuration. Telomeres associated in pairs were seen at zygotene. The high degree of polarization of meiotic nuclei continues for an exceptionally long period, i.e., during zygotene–pachytene into the diplotene contraction stage. The Rabl-polarized meiotic architecture and clustering of pericentromeres suggest a high complexity of karyotypes, not only in structural heterozygotes but also in bivalent-forming homozygous species.

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15

Rowley, John R., and Bjorn Walles. "Cell differentiation in microsporangia of Pinus sylvestris. V. Diakinesis to tetrad formation." Nordic Journal of Botany 13, no. 1 (1993): 67–82. http://dx.doi.org/10.1111/j.1756-1051.1993.tb00018.x.

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16

Koul, Kuldeep Kumar, Ranjna Nagpal, and Shayat Kumar. "Variable multivalent orientations during diakinesis and metaphase I in microsporocytes ofTradescantia spathaceaSw." Caryologia 66, no. 2 (2013): 145–53. http://dx.doi.org/10.1080/00087114.2013.821839.

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Zheng, Jin-shuang, Cheng-zhen Sun, Shu-ning Zhang, and Xi-lin Hou. "Karyotype of mitotic metaphase and meiotic diakinesis in non-heading Chinese cabbage." Plant Systematics and Evolution 300, no. 2 (2013): 295–302. http://dx.doi.org/10.1007/s00606-013-0882-y.

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18

Cutillas, C., D. C. Guevara, A. Valero, and C. Ariza. "Protostrongylus rufescens: a cytogenetic study." Journal of Helminthology 61, no. 1 (1987): 72–76. http://dx.doi.org/10.1017/s0022149x00009755.

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ABSTRACTThe diploid chromosome number of Protostrongylus rufescens is 2n=11 for males and 2n=12 for females. So, the sex determinism mechanism is XO/XX. The study of the genetic behaviour of this species has been made. In diakinesis stage the bivalents show typical tetrads with cross, Ø, and lineal configurations. The division of the sexual chromosome is prereductional for the first meiotic division.

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19

Rufas, J. S., J. L. Santos, M. Diez, and J. A. Suja. "Meiotic chromosome structure: relationship between the synaptonemal complex and the chromatid cores." Genome 35, no. 6 (1992): 1054–61. http://dx.doi.org/10.1139/g92-162.

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The development of silver-stained synaptonemal complexes (SCs) and of chromatid cores was analyzed in squashed and surface-spread grasshopper spermatocytes using light and electron microscopy, respectively. This study was conducted to determine the relationship of the two chromosome structures and then obtain more insight into the meiotic chromosome structure. Pachytene cells observed by light microscopy showed thin silver-stained threads, representing SCs, along the centre of the bivalents. However, fully formed SCs, and an axial element corresponding to the univalent sex chromosome, appeared when these cells were observed by electron microscopy. During early diplotene no silver-stained threads were observed by light microscopy. However, fragmentation of the SCs was apparent in cells at the same stage when observed by electron microscopy. Both light and electron microscopy showed that chromosome cores were first detected in homologues of late diplotene – early diakinesis cells. During diakinesis the cores were not continuous but were interrupted where interstitial chiasmata occur. In prometaphase I – metaphase I cells these cores appeared continuous and double, i.e., each chromatid clearly showed its own core. We propose a model whereby the associated cores of sister chromatids act as frameworks for the formation of the SC lateral elements.Key words: meiosis, chromosome structure, synaptonemal complex, chromatid core.

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Dulic, Beatrice, and Nina De Luca. "Karyotype of horvath's rock lizard Lacerta (Archaeolacerta) horvathi Mehely, 1904 (Reptilia: Lacertidae)." Amphibia-Reptilia 9, no. 4 (1988): 353–56. http://dx.doi.org/10.1163/156853888x00026.

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AbstractKaryotype analysis of 2 male horvath's rock lizard, Lacerta (Archaeolacerta) horvathi, found 2n = 36 in both somatic and spermatogonial metaphases. All the chromosomes are acrocentric. In diakinesis, 18 bivalents are visible. Microchromosomes, characteristic of most lacertid karyotypes, are absent in this species. In a single metaphase, satellites were observed on the 8th pair of chromosomes. Male sex chromosomes have not been determined. Overall, the karyotype of Lacerta horvathi is similar to that of Lacerta vivipara,

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Motlík, Jan, Peter Šutovský, Jaroslav Kalous, Michal Kubelka, Jiří Moos, and Richard M. Schultz. "Co-culture with pig membrana granulosa cells modulates the activity of cdc2 and MAP kinase in maturing cattle oocytes." Zygote 4, no. 3 (1996): 247–56. http://dx.doi.org/10.1017/s0967199400003166.

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SummaryBovine cumulus-enclosed oocytes, initially cultured up to diakinesis (8h of initial culture) or metaphase I (12h of initial culture), were subsequently co-cultured for 6 h in contact with pig membrana granulosa (PMG) cells and then assayed for histone H1 and MAP kinase activities. In addition, the phosphorylation state of ERK 1,2 proteins was determined by Western blotting. The alterations in nuclear envelope breakdown, meiotic spindle formation and the patterns of chromosome condensation were analysed by immunofluorescence and transmission electron microscopy. The diakinesis-stage oocytes (initially cultured for 8h) already possessed high histone H1 kinase and MAP kinase activities that were correlated with condensed and partially individualised chromosomes. The ERK 1 and most ERK 2 proteins were partly phosphorylated. Following the 6h co-culture of these oocytes with PMG a rapid decrease in MAP kinase activity and a slower decrease in histone H1 kinase occurred, as well as ERK 1 and ERK 2 dephosphorylation. Both kinase activities and ERK 1,2 phosphorylation were fully restored following the release of the oocytes from co-culture and a subsequent culture in the absence of PMG. Moreover, the clumped bivalents were reindividualised and 56% of these oocytes reached metaphase II after 20 h of culture without PMG. The metaphase I oocytes, initially cultured for 12 h, displayed a fusiform meiotic spindle and a metaphase array of chromosomal bivalents, accompanied by high levels of both histone H1 and MAP kinase activity. Co-culture of MI oocytes with PMG abolished the activity of both kinases and caused the dephosphorylation of ERK 1 and ERK 2. Furthermore, the spindle microtubules were depolymerised and the chromosomal bivalents clumped into a single mass. Neither of the protein kinase activities nor the meiotic spindle were restored following subsequent culture in the absence of PMG for up to 20 h. These observations indicate that under in vitro conditions membrana granulosa cells can cause a prompt decrease in histone H1 and MAP kinase activities, and metaphase I oocytes. While these events are fully reversible in late diakinesis oocytes, metaphase I oocytes did not complete maturation after release from co-culture.

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Röder, G., K. E. Linsenmair, I. Nanda, and M. Schmid. "On sex determination in the Turkish desert woodlouse Hemilepistus elongatus (Crustacea, Isopoda, Oniscidea): searching for sex chromosomes and for sex-specific differences in simple DNA repeats." Genome 39, no. 4 (1996): 818–21. http://dx.doi.org/10.1139/g96-103.

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The karyotype of male and female Hemilepistus elongatus was investigated by means of C-banding. The diploid chromosome number in both sexes is 2n = 50. By scrutinizing general morphology and localization of the constitutive heterochromatin, no heteromorphic sex chromosomes were found. All chromosome pairs in males are well paired during diakinesis. Hybridization of genomic DNA with (GACA)4 and (GATA)4 oligonucleotides revealed no sex-specific patterns. Key words : karyotype, C-banding, sex determination, simple DNA-repeats, Isopoda.

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Santos-Serejo, Janay A., José R. Gardingo, Mateus Mondin, and Margarida L. R. Aguiar-Perecin. "Alterations in Heterochromatic Knobs in Maize Callus Culture by Breakage-Fusion-Bridge Cycle and Unequal Crossing Over." Cytogenetic and Genome Research 154, no. 2 (2018): 107–18. http://dx.doi.org/10.1159/000488067.

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The meiotic and mitotic behavior of regenerated plants derived from a long-term callus culture, designated 12-F, was analyzed. This culture was heterozygous for an amplification of the heterochromatic knob on the long arm of chromosome 7 (K7L). We aimed to investigate if the amplification resulted from a breakage-fusion-bridge (BFB) cycle or from unequal sister chromatid recombination. Therefore, C-banded mitotic metaphases and pachytene, diakinesis, and anaphase I of regenerated plants were analyzed. Additionally, the occurrence of alterations in K7L was investigated in C-banded metaphases from short-term callus cultures derived from lines related to the donor genotype of the 12-F culture. As a result, plants homozygous and heterozygous for the amplification were detected. Meiosis was normal with few abnormalities, such as a low frequency of univalents at diakinesis. In the callus cultures a chromosome 7 with knobs of different sizes in the sister chromatids was detected and interpreted as a result of unequal crossing over. Other chromosomal alterations were consistent with the occurrence of BFB cycles. The finding of unequal crossing over in the cultures supports the conclusion that the amplification in the culture 12-F would be derived from this mechanism. If the amplification was derived from a BFB cycle, the terminal euchromatic segment between knob and the telomere would be deleted, and possibly, homozygous plants would not be viable.

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Arslan, Orhan, Şenol Bal, Semra Mirici, and Nilgün Yenice. "MEIOTIC STUDIES IN THE M2 GENERATION OF Helianthus annuus L. VARIETY EKIZ 1 AFTER GAMMA IRRADIATION / LOS ESTUDIOS EN LA GENERACION DE Helianthus annuus L. LA VARIEDAD EKIZ 1 DESPUES DE LA IRRADIACION DE LA GAMMA / APRÉS LE RAYONNEMENT DES GAMMA DANS LA GÉNÉRATION M2 DE LA VARIÉTÉ EKIZ 1 (Helianthus annuus L.)." HELIA 24, no. 35 (2001): 33–38. http://dx.doi.org/10.1515/helia.2001.24.35.33.

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SUMMARYThe effect of gamma rays on meiosis in the M2 generation has been studied in sunflower (Helianthus annuus L.) variety Ekiz 1. Seeds were irradiated with gamma rays at 10, 20, 30, 40 and 50 kR doses. Radiation induced meotic abnormalities. The chromosomal aberrations included univalents, multivalents and stickiness at diakinesis, laggards and stickiness at metaphase I, bridges and laggards at anaphase and telophase I-II, micronuclei at telophase II. The percentage frequencies of anomalies increased generally with the increasing dose of radiation.

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Rodríguez-Romero, F. "Meiotic Behaviour During Pachytene And Diakinesis Of Isognomon Alatus (Molusca-Isognomonidae) From Veracruz, Mexico." Ciencias Marinas 17, no. 1 (1991): 73–78. http://dx.doi.org/10.7773/cm.v17i1.781.

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26

Risso-Pascotto, Claudiceia, Maria Suely Pagliarini, and Cacilda Borges do Valle. "Chromosome number and microsporogenesis of two accessions of Brachiaria dura Stapf (Poaceae)." Biota Neotropica 9, no. 2 (2009): 257–61. http://dx.doi.org/10.1590/s1676-06032009000200024.

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The two accessions of B. dura analyzed (DU01 and DU02) are hexaploid (2n = 6x = 54), derived from x = 9. Meiotic abnormalities, such as precocious chromosome migration to the poles, laggards and micronuclei, were recorded in low frequency in both accessions. The few multivalent chromosome association at diakinesis and meiotic stability suggested that hexaploidy probably resulted from chromosome doubling. In DU02, chromosome transfer (cytomixis) among meiocytes, involving part or the entire genome was observed. The implication of these findings for the Brachiaria breeding is discussed.

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Wagenvoort, M. "Spontaneous structural rearrangements in Solanum phureja Juz. et Buk. 2. Meiotic behaviour and identification of interchange chromosomes using primary trisomics." Genome 38, no. 1 (1995): 140–47. http://dx.doi.org/10.1139/g95-017.

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Meiosis was studied in two diploid (2n = 2x = 24) siblings of Solanum phureja Juz. et Buk. and in 11 disomic and 2 trisomic descendants. The diploid siblings carry the same heterozygous interchange and either one or two inversions. The frequency of quadrivalents at diakinesis/metaphase I in these clones was 0.56 and 0.62 per pollen mother cell. In two plants from the first inbred generation (I1) this frequency was about the same but in some other I1 plants and a full sib the frequency was substantially lower, varying from 0.00 to 0.16. Most quadrivalents, 78–83%, were rings. A variety of quadrivalent configurations at diakinesis and metaphase I was observed, giving rise to balanced and unbalanced gametes. The absence of ring quadrivalents in trisomic descendants of one of the siblings implied that tertiary trisomics or primaries being homozygous for the interchange were present in the I1 generation. Regular chromosome distribution (12–12) at anaphase I occurred in 46.5 and 73.2% of the pollen mother cells studied in the two original clones. Irregularities, such as 11–13 distribution, lagging chromosomes, and a bridge and fragment, were detected on average in 2.7, 3.3, and 32.5%, respectively, of the anaphase I cells analysed. In hybrids from crosses between 6 primary trisomics as females with the interchange heterozygote, the involvement in the interchange of chromosomes 3 and 12 was clearly demonstrated.Key words: Solanum phureja, interchange heterozygote, chromosome identification, interchange trisomic, meiosis.

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Czaban, B. Barbara, and Arthur Forer. "Rhodamine-labelled phalloidin stains components in the chromosomal spindle fibres of crane-fly spermatocytes and Haemanthus endosperm cells." Biochemistry and Cell Biology 70, no. 8 (1992): 664–76. http://dx.doi.org/10.1139/o92-102.

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In crane-fly spermatocytes and Haemanthus endosperm, all metaphase and anaphase chromosomal spindle fibres were stained with rhodamine-labelled phalloidin. In crane-fly spermatocytes, each kinetochore was stained with rhodamine-labelled phalloidin at diakinesis of prophase and after colcemid caused metaphase spindles to depolymerize. Since phalloidin stains actin filaments, the distributions of rhodamine-labelled phalloidin-stained material in crane-fly spermatocytes and Haemanthus endosperm suggest that actin filaments might interact with microtubules to produce forces that move chromosomes during cell division, either directly or via an intermediate motor molecule.Key words: phalloidin, chromosomal spindle fibres, kinetochores.

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29

Bickham, John W., Kent M. Reed, Russell A. Mittermeier, et al. "Cytogenetic analysis of the pleurodine turtle Phrynops hogei and its taxonomic implications." Amphibia-Reptilia 12, no. 2 (1991): 203–12. http://dx.doi.org/10.1163/156853891x00176.

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AbstractConventional chromosomal preparations of the Brazilian sidenecked turtle Phrynops hogei indicate the karyotype of this species (diploid number 2n = 58; fundamental number FN = 64) is identical to that reported for other members of the genus. Electron microscopic analysis of whole-cell complements of synaptonemal complexes corroborated the karyotypic description and provided definitive resolution of the acrocentric condition of the microchromosomes. Additionally, this approach provided a continuous sequence of prophase I nuclei which enabled detailed description of chromosomal behavior from leptonema through diakinesis and the sequence of centriolar replication.

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30

Anisimov, Alim P., Galina V. Roslik, and Gennady N. Ganin. "Cytogenetic description of the earthworm Drawida ghilarovi Gates, 1969 (Oligochaeta, Moniligastridae) from the southern Russian Far East." Comparative Cytogenetics 9, no. (4) (2015): 565–77. https://doi.org/10.3897/CompCytogen.v9i4.5741.

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Sixty-six specimens of the earthworm Drawida ghilarovi Gates, 1969 (Oligochaeta, Moniligastridae) from 15 localities of the southern Russian Far East were studied cytogenetically. We examined chromosome sets during mitosis and diakinesis as well as DNA content in the spermatogenous and somatic cell nuclei. The populations and morphs displayed no differences in karyotype and ploidy levels estimated in terms of both chromosome number and DNA mass index: n = 10, 2n = 20; c = 1.1 pg, 2c = 2.2 pg. We conclude that polyploidy as a species- or race-forming factor is not typical of these earthworms.

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31

Clemons, Amy M., Heather M. Brockway, Yizhi Yin, et al. "akirin is required for diakinesis bivalent structure and synaptonemal complex disassembly at meiotic prophase I." Molecular Biology of the Cell 24, no. 7 (2013): 1053–67. http://dx.doi.org/10.1091/mbc.e12-11-0841.

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During meiosis, evolutionarily conserved mechanisms regulate chromosome remodeling, leading to the formation of a tight bivalent structure. This bivalent, a linked pair of homologous chromosomes, is essential for proper chromosome segregation in meiosis. The formation of a tight bivalent involves chromosome condensation and restructuring around the crossover. The synaptonemal complex (SC), which mediates homologous chromosome association before crossover formation, disassembles concurrently with increased condensation during bivalent remodeling. Both chromosome condensation and SC disassembly are likely critical steps in acquiring functional bivalent structure. The mechanisms controlling SC disassembly, however, remain unclear. Here we identify akir-1 as a gene involved in key events of meiotic prophase I in Caenorhabditis elegans. AKIR-1 is a protein conserved among metazoans that lacks any previously known function in meiosis. We show that akir-1 mutants exhibit severe meiotic defects in late prophase I, including improper disassembly of the SC and aberrant chromosome condensation, independently of the condensin complexes. These late-prophase defects then lead to aberrant reconfiguring of the bivalent. The meiotic divisions are delayed in akir-1 mutants and are accompanied by lagging chromosomes. Our analysis therefore provides evidence for an important role of proper SC disassembly in configuring a functional bivalent structure.

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Ayoub Bhatti, Arshad, and Manvi Khajuria. "Karyotypic and Morphometric Analysis of A Predatory Rove Beetle, Paederus littoralis (Coleoptera: Staphylinidae) from Jammu Region of Outer Himalayas, India." Biosciences, Biotechnology Research Asia 15, no. 2 (2018): 495–99. http://dx.doi.org/10.13005/bbra/2654.

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In the present study, the chromosomes of a predatory rove beetle Paederus littoralis were studied from Jammu region of outer Himalayas. These beetles are also potential bio-control agents in suppressing the populations of cereal aphids. The diploid chromosome number was found to be 2n=32 including 22 metacentric, 3 submetacentric, 6 subtelocentric and 1 telocentric chromosomes. The sex chromosomes (Xyp) included submetacentric X and telocentric y chromosome. Meiotic observations comprised diplotene, diakinesis and metaphase-I. The study is helpful in solving taxonomic problems with in the family Staphylinidae and it authenticates the existence of this particular species through chromosomal data.

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Wang, Fang, John Yoder, Igor Antoshechkin, and Min Han. "Caenorhabditis elegans EVL-14/PDS-5 and SCC-3 Are Essential for Sister Chromatid Cohesion in Meiosis and Mitosis." Molecular and Cellular Biology 23, no. 21 (2003): 7698–707. http://dx.doi.org/10.1128/mcb.23.21.7698-7707.2003.

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ABSTRACT Sister chromatid cohesion is fundamental for the faithful transmission of chromosomes during both meiosis and mitosis. Proteins involved in this process are highly conserved from yeasts to humans. In screenings for sterile animals with abnormal vulval morphology, mutations in the Caenorhabditis elegans evl-14 and scc-3 genes were isolated. Defects in cell divisions were observed in germ line as well as in vulval and somatic gonad lineages. Through positional cloning of these genes, we have shown that EVL-14 and SCC-3 are likely the only C. elegans homologs of the yeast sister chromatid cohesion proteins Pds5 and Scc3, respectively. Both evl-14 and scc-3 mutants displayed defects in the meiotic germ line. In evl-14 mutants, synaptonemal complexes (SCs) were detectable but more than the usual six DAPI (4′,6′-diamidino-2-phenylindole)-positive structures were seen at diakinesis, suggesting that EVL-14/PDS-5 is important for the maintenance of sister chromatid cohesion in late prophase. In scc-3 mutant animals, normal SCs were not visible and ∼24 DAPI-positive structures were seen at diakinesis, indicating that SCC-3 is necessary for sister chromatid cohesion. Immunostaining revealed that localization of REC-8, a homolog of the yeast meiotic cohesin subunit Rec8, to the chromosomes depends on the presence of SCC-3 but not that of EVL-14/PDS-5. scc-3 RNA interference (RNAi)-treated embryos were 100% lethal and displayed defects in cell divisions. evl-14 RNAi caused a range of phenotypes. These results indicate that EVL-14/PDS-5 and SCC-3 have functions in both mitosis and meiosis.

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Chiriac, Gheorghe, Larisa Andronic, Valeriu Bujoreanu, and Liliana Marii. "Features of crossing-over in virus-infected tomato." Open Life Sciences 1, no. 3 (2006): 386–98. http://dx.doi.org/10.2478/s11535-006-0022-6.

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AbstractThe evidence of increased crossing over rate in tomato hybrids infected with TAV (Tomato aspermy virus), PVX (Potato virus X), TMV (Tobacco mosaic virus), TMV+PVX indicates the recombinogenic effect of viral infection. Cytological studies of the early diakinesis in healthy and virus-infected tomato revealed significant changes in chiasma number and position. The most significant changes were established for bivalents with two interstitial chiasmata and with one terminal and one interstitial. The data obtained indicate redistribution of the chiasmata position and induction of additional exchanges. The virus-induced recombination is segment-specific and depends on the host plant genotype, virus infection and the interaction between them.

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Sudman, Philip D., and Ira F. Greenbaum. "Visualization of kinetochores in mammalian meiotic preparations and observations of argentophilic differences between mitotic and meiotic kinetochores." Genome 32, no. 3 (1989): 380–82. http://dx.doi.org/10.1139/g89-458.

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Brief staining with AgNO3 was found to differentially stain the kinetochores of chromosomes from diakinesis – metaphase I and metaphase II nuclei of mammals. The results differ from those of Giemsa-stained or C-banded preparations as the silver-stained meiotic kinetochores are clearly distinguishable from both constitutive heterochromatin and euchromatin. Silver-staining is presented as a valuable method for the staining of meiotic material because it allows for the positive identification of centromeric position and orientation with respect to chiasmata. The nonargentophilic nature of the centromere (kinetochore) region of spermatogonial metaphase chromosomes in some species suggests a fundamental structural difference between mitotic and meiotic kinetochores.Key words: kinetochore, meiosis, mammal.

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36

Noronha, Renata Coelho Rodrigues, Bruno Rafael Ribeiro de Almeida, Marlyson Jeremias Rodrigues da Costa, Cleusa Yoshiko Nagamachi, and Julio Cesar Pieczarka. "Synaptic behavior of Leptodactylus pentadactylus (Anura: Leptodactylidae) by immunolocalization of proteins." Semina: Ciências Biológicas e da Saúde 38, no. 1supl (2018): 242. http://dx.doi.org/10.5433/1679-0367.2017v38n1suplp242.

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Most species of the genus Leptodactylus share similar karyotypes, with 2n=22 and NF=44. The species L. pentadactylus presents a multivalent in its karyotype, resulting from multiple translocations, forming a ring chromosome during meiosis I. In this study analyzed the meiotic behavior of L. pentadactylus, from Brazilian Amazonia, through immunoprotein markers. Testicular tissues of an adult male were collected and analyzed by immunofluorescence microscopy, using antibodies to detect the following meiotic proteins: SMC3, component of chromosomal axis, and responsible for cohesion between sister chromatids; ?-H2AX in a protein marker of meiotic silencing of unsynapsed chromatin (MSUC). The results showed that: in leptotene, SMC3 and ?-H2AX mark fuzzy segments throughout all the chromatin; in the zygotene; regions that start synapses are intensely marked by ?-H2AX; in turn, with the advancement of the synapse at the end of the zygotene, ?-H2AX markings expand evenly in the chromatin; in pachytene, the synapsis remains incomplete, and several asynaptic regions were noted, with ?-H2AX markings more intense on synapsed regions of chromosomes involved or not in multivalent links; in diplotene, the synaptonemal complex is disorganized, SMC3 cohesin is present on partially decondensed, chromatin, and ?-H2AX markings are present only in some regions; in diakinesis, SMC3 maintains the same pattern of diplotene, however, ?-H2AX markings are quite reduced. The results of meiotic behavior of L. pentadactylus show asynaptic axes in pachytene, which probably do not present homology with each other, corresponding to segments that suffered multiple rearrangements. SMC3 pattern and reduction of ?-H2AX markings in diplotene, suggest decondensation of chromatin, with reactivation of transcription in chromosomal handles. The absence of ?-H2AX markings in diakinesis show that the rearranged chromosomes of L. pentadactylus do not compromise the spermatogenesis of the animal, ensuring its meiotic dynamic and fertility.

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Santamour, Frank S. "Flowering and Fertility of Hybrids Between Spring- and Fall-flowering Elms." HortScience 24, no. 1 (1989): 139–40. http://dx.doi.org/10.21273/hortsci.24.1.139.

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Abstract Hybrids between diploid (2n = 28 chromosomes) elm (Ulmus) species that normally flower in March or April and those that normally flower in August or September flowered at various times from late October to mid-November when grown in Washington, D.C. Although such hybrids did not produce viable seed, they did produce apparently sound pollen. Chromosome pairing at diakinesis in pollen mother-cells in most of the diploid hybrids was sufficiently complete to allow normal meiosis to take place. An aneuploid (2n = 39) three-species hybrid with a preponderance of chromosomes from spring-flowering species produced abnormal flower buds in which meiosis took place later in the spring than American elm, but did not undergo anthesis.

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38

Bui Hong, T., L. G. Villa-Diaz, E. Yamaoka, and T. Miyano. "309CHROMOSOME CONDENSATION IS CORRELATED WITH HISTONE H3 PHOSPHORYLATION WITHOUT CDC2 KINASE AND MAP KINASE ACTIVITIES IN PIG OOCYTES." Reproduction, Fertility and Development 16, no. 2 (2004): 273. http://dx.doi.org/10.1071/rdv16n1ab309.

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Chromosome condensation is the first step of oocyte maturation. When the oocytes resume meiosis, chromosomes start to condense and Cdc2 kinase becomes activated. However, recent findings show that the chromosome condensation does not always correlate with Cdc2 kinase activity in pig oocytes. The objectives of this study were to examine (1) the correlation between chromosome condensation and histone H3 phosphorylation at serine 10 (Ser10) during meiotic maturation of pig oocytes, and (2) the effects of protein phosphatase 1/2A (PP1/PP2A) inhibitors on the chromosome condensation and the involvement of Cdc2 kinase, MAP kinase and histone H3 kinase in this process. Oocyte-cumulus-granulosa cell complexes (OCGCs) were collected from follicles of 4–6mm in diameter. OCGCs were cultured in modified TCM 199 for different periods of time to obtain oocytes at the germinal vesicle (GV, 0h), diakinesis (18h), metaphase I (24–27h), anaphase I to telophase I (30–33h), and metaphase II (42h) stages. To examine the effects of PP1/PP2A inhibitors on the chromosome condensation, oocyte-cumulus-complexes (OCCs) were cultured in modified TCM 199 with either 2.5μM okadaic acid (OA) or 50nM calyculin A (CL-A) for 0.5, 1, 2, 3, 4 and 6h. To inhibit the MAP kinase activity in the oocytes treated with the PP1/PP2A inhibitor, OCCs were cultured in medium containing CL-A and the MEK inhibitor, U0126 (0.1mM). Morphology of the chromosome and nuclear membrane, and phosphorylation of histone H3 were examined by the immunofluorescent microscopy. In each group 30 oocytes were examined for OA or CL-A and 60 oocytes for CL-A+U0126 treatments. Activities of Cdc2 kinase, MAP kinase and histone H3 kinase were also examined. Phosphorylation of histone H3 (Ser10) was not detected in the oocytes at the GV stage. The phosphorylation was first detected in the clump of condensed chromosomes at the diakinesis stage of prophase I and maintained until metaphase II. The kinase assay also showed that histone H3 kinase activity was low in GV oocytes, increased at the diakinesis stage, and then maintained high activity until metaphase II. PP1/PP2A inhibitors induced rapid chromosome condensation in pig oocytes. Histone H3 phosphorylation (Ser10) became detectable together with the chromosome condensation in the treated oocytes after 2h. After 6h, oocytes had highly condensed chromosomes with phosphorylated histone H3 (81% in CL-A- and 71% in OA-treated oocytes). Both histone H3 kinase and MAP kinase were activated in the treated oocytes, although Cdc2 kinase was not activated. In the oocytes treated with CL-A and U0126, neither Cdc2 kinase nor MAP kinase were activated, although histone H3 kinase was still activated and chromosomes condensed. These results suggest that phosphorylation of histone H3 (Ser10) occurs in condensed chromosomes during maturation in pig oocytes. Futhermore, the chromosome condensation is correlated with histone H3 kinase activity, but not with Cdc2 kinase and MAP kinase activities.

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39

Johnston, S. A., R. W. Ruhde, M. K. Ehlenfeldt, and R. E. Hanneman Jr. "Inheritance and microsporogenesis of a synaptic mutant (sy-2) from Solanum commersonii Dun." Canadian Journal of Genetics and Cytology 28, no. 4 (1986): 520–24. http://dx.doi.org/10.1139/g86-076.

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A mutant has been found in diploid Solanum commersonii (2n = 2x = 24) in which no bivalents are formed during microsporogenesis. This trait, a simply inherited recessive, has been designated sy-2. It conditions high levels of pollen sterility through random chromosome segregation at anaphase I. Only the nucleolar-associated chromosomes appear to segregate non-randomly, possibly due to the fusion of the nucleoli as cells near diakinesis. Branched spindle configurations result in multipolar telophase I arrangements, yielding from one to seven pollen grains at the tetrad stage. Most of the stainable pollen produced appears to be 2n. The 2n pollen formed by this mechanism should bear the exact genotype of the parent, since no crossing-over occurs.Key words: Solanum, potato, 2n gametes, mutants (meiotic), mutants (synaptic).

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40

Kaur, Harbhajan, and B. Semahagn. "Meiotic behaviour of chromosomes in three predator species of the subfamily Asopinae (Heteroptera: Pentatomidae)." Comparative Cytogenetics 4, no. (2) (2010): 133–39. https://doi.org/10.3897/compcytogen.v4i2.47.

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The study of chromosome behaviour has been carried out on males of three species of the Asopinae (Pentatomidae) bugs Andrallus spinidens (Fabricius, 1787), Canthecona furcellata Wolff, 1801 and Perillus bioculatus (Fabricius, 1775) collected in India. All the species have XY sex chromosome system and 12 autosomes (2n=14=12A+XY). The general course of meiosis is fairly uniform and is typical for heteropteran species. However, the species differ in the extent of decondensation of the autosomes during the diffuse stage and the number of ring bivalents at diplotene/diakinesis. Also, a metaphase I arrangement of chromosomes which is different from the typical Pentatomidae type has been observed in C. furcellata and P. bioculatus.

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Wang, Renxiang, Wen Shao, and Ling Liu. "Cytotaxonomic Study of Hypodematium (Hypodematiaceae) from China." Phytotaxa 161, no. 2 (2014): 101. http://dx.doi.org/10.11646/phytotaxa.161.2.1.

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Chromosome numbers and reproductive biology of nine species of the fern genus Hypodematium (Hypodematiaceae) from China were investigated. The chromosome numbers of eight species are reported here for the first time: H. daochengensis n=41 (41 II); H. fordii n=40 (40 II), n=80 (40 II+40 I), 2n=120; H. glanduloso-pilosum n=41 (41 II), 2n=82, 2n=123; H. gracile n=41 (41 II); H. hirsutum n= 41 (41 II); H. microleptoides n=41 (41 II); H. sinense n= 40 (40 II) and H. squamuloso-pilosum n=41 (41 II). Two cytotypes, n=82 (41 II+41 I) and 2n=123 in H. crenatum, are reported for the first time. Our results showed that the species with these cytotypes are agamospermous triploids: H. crenatum n = 82 (41 II +41 I), H. glanduloso-pilosum n = 82 (41 II +41 I) and H. fordii n = 80 (40 II +40 I), based on the unequal size and presence of aborted spores in the sporangium, and the allotriploid hybrid chromosomes in the spore mother cell at the diakinesis stage of meiosis I. The remaining species are sexual diploids and tetraploids, based on the chromosome number n = 41 and n =82 at the diakinesis stage of meiosis I of spore mother cells. The relationships among habitat preferences, frond hairs and reproductive modes in Hypodematium are discussed and illustrated. It appears that plants with large fronds and sparse, thin hairs, living in humid and shady places undergo sexual reproduction, while small plants living in sunny and dry conditions with thick hairs undergo agamospermous reproduction. The distribution pattern and basic chromosome number all indicated the basic chromosome number x= 41 was plesiomorphic, whereas x=40 was apomorphic. Chromosome aneuploid changes occurred in this genus. The distribution of the sexual diploids and tetraploids and agamospermous triploids suggests that the genus might have originated in the Himalayas and dispersed from there to northeast Asia and Japan.

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Bhatti, Arshad Ayoub, Nidhi Slathia, and Manvi K. "First Report on Karyotypic, Morphometric and Meiotic Analysis of a Predatory Bombardier Beetle Pherosophus catoirai (Coleoptera: Carabidae) from Jammu region of Outer Himalayas, India." Biosciences Biotechnology Research Asia 18, no. 4 (2021): 817–22. http://dx.doi.org/10.13005/bbra/2963.

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Chromosomal studies and manual karyotyping are the aged techniques for determining the identity of a species on evolutionary scale; however, these techniques are simple, reliable and inexpensive to authenticate the existence of a particular species. In the present work, the chromosome complement and meiotic processes of a predatory bombardier beetle Pherosophus catoirai were investigated. This species presented 2n=35 as diploid chromosome number and the chromosomal formula was found to be 12m+8sm+12st+X0. Sex mechanism was X0 type with metacentric X chromosome. Y chromosome was absent in this species. Karyotype revealed small chromosomes except X chromosome which is found to be largest in the spermatogonial metaphase stage. Meiotic stages were pachytene, diplotene, diakinesis and metaphase-I. Present study may find importance to analyse evolution of chromosomes in order Coleoptera particularly in family Carabidae.

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Ferreira, Kátia, Giovana Augusta Torres, Isabelle Vilela de Carvalho, and Lisete Chamma Davide. "Abnormal meiotic behavior in three species of Crotalaria." Pesquisa Agropecuária Brasileira 44, no. 12 (2009): 1641–46. http://dx.doi.org/10.1590/s0100-204x2009001200012.

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The objective of this work was to compare the meiotic behavior and pollen grain viability of three species of Crotalaria. Slides for meiotic analysis were prepared by the air-drying technique. Pollen grain viability was measured by three staining procedures (Alexander's solution, tetrazolium chloride and fluorescein diacetate) and in vitro germination in a sucrose solution. Eight bivalents were observed, confirming previous reports on populations from other regions of Brazil, as well as from other countries. All species showed abnormal meiotic behavior as follows: in Crotalaria micans, cytomixis and abnormal chromosome pairing in diakinesis; in C. spectabilis, abnormal chromosome pairing in diplotene; in C. zanzibarica, shrunk nuclei in leptotene and zygotene. Pollen grains of all three species show low viability, which may be associated with the irregularities of the meiotic behavior.

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Schmid, Michael, Claus Steinlein, and Heinz Winking. "Multicolor Spectral Analyses of Mitotic and Meiotic Mouse Chromosomes Involved in Multiple Robertsonian Translocations. I. The CD/Cremona Hybrid Strain." Cytogenetic and Genome Research 147, no. 4 (2015): 253–59. http://dx.doi.org/10.1159/000444597.

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Multicolor spectral analysis (spectral karyotyping) was applied to mitotic and male diakinetic chromosomes of hybrid mice carrying a unique system of 18 autosomal Robertsonian translocation chromosomes with alternating arm homologies. Only the autosomes 19 and the XY sex chromosomes are excluded from these Robertsonian translocations. The translocations, previously identified by conventional banding analyses, could be verified by spectral karyotyping. Besides the Robertsonian translocations, no other interchromosomal rearrangements were detected. In diakineses of male meiosis, the 18 metacentric Robertsonian translocation chromosomes form a very large meiotic ‘superring'. The predictable, specific order of the chromosomes along this ‘superring' was completely confirmed by multicolor spectral analysis. In the majority of diakineses analyzed, the free autosomal bivalent 19 and the XY sex bivalent form a conspicuous complex which tightly associates with the 12;14 Robertsonian translocation chromosome in the ‘superring'.

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Hernández, Marcela A., Aldo R. Andrada, Valeria de los A. Páez, and Olga G. Martínez. "Ploidy level and obligate apogamy in two populations of Argyrochosma nivea var. tenera (Pteridaceae)." Hoehnea 42, no. 2 (2015): 233–37. http://dx.doi.org/10.1590/2236-8906-36/2014.

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ABSTRACT Argyrochosma nivea var. tenera is a cheilanthoid fern from the American continent. We present herewith the study of meiotic behavior and gametic number as well as number of spores and reproduction mode (with observations from cultured gametophytes). The study material is from Northwestern Argentina. For the study of meiosis, sporangia were fixed in ethanol-acetic acid (3:1) and stained with 2% propionic haematoxylin. Micrographs were taken using light and scanning electron microscopes. Meiotic chromosome number is 2n = 3x = 81 and the presence of lagging chromosomes at telophase II is mentioned for the first time; three sets of chromosome occur at diakinesis. Sporangia have 32 trilete spores. Adult gametophytes are laminar, cordiform, asymetrical, glabrous, without glandular trichomes. In our samples, the adult gametophytes were neuter, without antheridia or archegonia, with obligate apogamous reproduction. Both populations studied might be of hybrid origin.

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Nazli, Afrin, and Kamini Kumar*. "Meiotic chromosome behavior of Haworthia limifolia." International Journal of Bioassays 5, no. 03 (2016): 4902. http://dx.doi.org/10.21746/ijbio.2016.03.009.

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Haworthia limifolia is a xerophytic plant belonging to the family Liliaceae and is indigenous to Africa. It is use extensively for its medicinal properties like antibacterial, antifungal properties and used for the treatment of sores, superficial burns, as a blood purifier and to promote pregnancy in women and cattles. In present investigation chromosomal behaviour of H. limifolia in meiosis was studied. In diplotene stage chiasmata was observed showing the possibilities of genetic recombination. Chromosome clumps were observed in diakinesis indicating sticky nature of chromosomes. Meiotic abnormalities like stickiness, precocious movement, formation of bridges and laggards were also reported in both meiosis I and II. A fairly high percentage of pollen sterility that is 73.41% was recorded resulting in failure of fruit formation. This plant could be designated as facultative apomict (Swanson, 1957) as the only means of reproduction found was asexual or vegetative.

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Kazimierski, T., and E. M. Kazimierska. "Iivestigations on hybrids in the genus Trifolium L. V. Fertility and cytogenetics of the hybrid Trifolium nigrescences Viv. x T. isthomocarpum Brot." Acta Societatis Botanicorum Poloniae 42, no. 4 (2015): 567–89. http://dx.doi.org/10.5586/asbp.1973.044.

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T.nigrescens (2n = 16) crosses with T .isthomocarpum (2n = 16) reciprocally. The viability of hybrid seedlings depend from the direction of the cross. At the time of diakinesis and metaphase I the average chromosome figures per PMC's was 7.014II, 0.005III, 0.435IV and 0.209I. For one half of the PMC's in the metaphase I the typical chromosome arrangement was 8II. The F1 plants was almost completly sterile. The causes of viability of hybrid seedlings depending on the direction of the cross, and the sterility of hybrid plants, are discussed.

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Oishi, Isao, Kenji Iwai, Yukiko Kagohashi, et al. "Critical Role of Caenorhabditis elegansHomologs of Cds1 (Chk2)-Related Kinases in Meiotic Recombination." Molecular and Cellular Biology 21, no. 4 (2001): 1329–35. http://dx.doi.org/10.1128/mcb.21.4.1329-1335.2001.

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ABSTRACT Although chromosomal segregation at meiosis I is the critical process for genetic reassortment and inheritance, little is known about molecules involved in this process in metazoa. Here we show by utilizing double-stranded RNA (dsRNA)-mediated genetic interference that novel protein kinases (Ce-CDS-1 and Ce-CDS-2) related to Cds1 (Chk2) play an essential role in meiotic recombination inCaenorhabditis elegans. Injection of dsRNA into adult animals resulted in the inhibition of meiotic crossing over and induced the loss of chiasmata at diakinesis in oocytes of F1animals. However, electron microscopic analysis revealed that synaptonemal complex formation in pachytene nuclei of the same progeny of injected animals appeared to be normal. Thus, Ce-CDS-1 and Ce-CDS-2 are the first example of Cds1-related kinases that are required for meiotic recombination in multicellular organisms.

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Lavania, U. C. "High bivalent frequencies in artificial autopolyploids of Hyoscyamus muticus L." Canadian Journal of Genetics and Cytology 28, no. 1 (1986): 7–11. http://dx.doi.org/10.1139/g86-002.

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Abstract:

High pollen and seed fertility of induced autotetraploids of the medicinal solanaceous plant Hyoscyamus muticus (4x = 56) could, at least in part, be attributed to low quadrivalent and high bivalent frequencies at metaphase I (MI). Mean configuration frequencies per cell were 3.45 ring quadrivalents, 0.49 chain quadrivalents, 0.55 trivalents, 5.98 ring bivalents, 12.67 open (rod) bivalents, and 1.34 univalents. In the diploid, ring bivalents were most common with chiasmata predominantly distal at diakinesis–MI. Different causes can explain the low quadrivalent frequencies in the tetraploids. Using a simple algebraic model, calculations show that the most probable explanation is reduced chiasma formation in one arm per chromosome, resulting from nonmedian partner exchange and special interference patterns. This agrees best quantitatively with high open (rod) bivalent frequencies compared with the diploid, accompanied by high ring quadrivalent frequencies.Key words: Hyoscyamus, autotetraploid, seed fertility, meiotic mechanism, pairing.

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Mekada, K., M. Harada, L. K. Lin, K. Koyasu, P. M. Borodin, and S. I. Oda. "Pattern of X-Y chromosome pairing in the Taiwan vole, Microtus kikuchii." Genome 44, no. 1 (2001): 27–31. http://dx.doi.org/10.1139/g00-091.

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Pairing of X and Y chromosomes at meiotic prophase and the G- and C-banding patterns and nucleolar organizer region (NOR) distribution were analyzed in Microtus kikuchii. M. kikuchii is closely related to M. oeconomus and M. montebelli, karyologically and systematically. The formation of a synaptonemal complex between the X and Y chromosomes at pachytene and end-to-end association at diakinesis metaphase I are only observed in three species in the genus Microtus; M. kikuchii, M. oeconomus, and M. montebelli. All the other species that have been studied so far have had asynaptic XY chromosomes. These data confirm that M. kikuchii, M. oeconomus, and M. montebelli are very closely related, and support the separation of asynaptic and synaptic groups on the phylogenetic tree.Key words: Microtus kikuchii, Microtus phylogeny, karyotype, synaptic sex chromosomes, synaptonemal complex.

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Journal articles on the topic 'Diakinesis'

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