Academic literature on the topic 'Chromosome number in okra'

Okra is a nutritious vegetable that belongs to the family Malvaceae. It is widely grown in the tropical, sub-tropical, temperate and Mediterranean regions of the world. However, little evidence of the impacts of high temperature stress on various physiological, morphological, biochemical and metabolic processes is available for okra nor is the extent of genetic variation known. This study characterized and evaluated 176 diverse okra germplasm under constant high temperature to assess morphological and physiological changes to growth and development and to identify molecular markers linked to heat tolerance. In the process, the ploidy level and genome size of diverse materials were established. Significant marker-trait associations (MTAs) were found for various morphological and phenological traits. These included days to fruiting, plant height and stem diameter, that once validated, could be used for marker-assisted breeding. Fruit nutrient analysis identified significant genotypic differences for Ca, Fe, and Na and some organic metabolites including sucrose. The accumulation of Ca, Na and Fe and sugars in the fruit of some genotypes acted not only as osmolytes or protectants during fruit development, but also influenced signal transduction and the maintenance of cell membrane integrity. High temperature also impacted pollen micromorphology. Tolerant genotypes had dehisced anthers and fully turgid and spined pollen grains with improved germination compared to sensitive genotypes. The optimal temperature for pollen germination was observed to be 25°C while temperatures above 45°C caused significant damage. Flow cytometry indicated that the relative number of chromosomes varied from 84-189 and ploidy level from 7x to16x. The genome size data were inadequate to accurately indicate the number of chromosomes. A negative correlation between relative ploidy and genome size showed a downsizing of the genome with increased ploidy level.

Mitosis and meiosis of five Plantago species were analyzed. Plantago argyrea, P. patagonica and P. wrightiana contain 2n = 20 chromosomes and P. rhodosperma and P. virginica 2n = 24 chromosomes. Similar modes of evolution of the karyotypes of the 2n = 20 species are suggested. All species are presumed to be tetraploid, arising from 2n = 10 and 2n = 12 ancestors. Structural changes in the karyotype of 2n = 12 species could produce one or more large chromosomes resulting in a decrease in chromosomes from 6 to 5. Consequently, chromosome lengths in 2n = 10 and derived 2n = 20 species could be increased by addition of repetitive DNA along the length of each chromosome to maintain chromosome field. Chromosomes of 2n = 24 species are more symmetrical and presumably more primitive than the 2n = 20 species. Chiasma frequencies in meiotic cells of all five species are similar. This suggests that the majority of changes DNA content are in repetitive DNA.

The correct number of chromosomes is important for the maintenance of healthy cells and organisms. Maintenance of a correct chromosome number depends on the accurate distribution of chromosomes to the daughter cells during cell division, and errors in chromosome segregation result in abnormal chromosome numbers, or aneuploidy. Aneuploidy is typically associated with deleterious effects on organismal and cellular fitness; however, aneuploidy has also been associated with enhanced cellular growth in certain contexts, such as cancer. Another type of deviation from the normal chromosome number can occur when entire sets of chromosomes are added to the normal (diploid) chromosome number, resulting in polyploidy. Whereas polyploidy is found in certain normal tissues and organisms, tetraploidy (four sets of chromosomes) is associated with a number of precancerous lesions and is believed to promote aneuploidy and tumorigenesis. While it is clear that chromosome mis-segregation causes aneuploidy, the effect of aneuploidy on chromosome segregation is less clear. Similarly, it is unclear whether and how tetraploidy may affect chromosome segregation. The work described here shows that aneuploidy can cause chromosome mis-segregation and induces chromosome-specific phenotypic effects. In contrast, tetraploidy does not per se induce chromosome mis-segregation, but enables the accumulation of aneuploidy thanks to a "genetic buffer" effect that allows tetraploid cells to tolerate aneuploidy better than diploid cells.<br>Ph. D.

Chromosome copy number aberrations are a leading cause of birth defects, stillbirths, pregnancy loss and infertility. Every human male has a proportion of chromosomally abnormal sperm however conditions such as infertility, cancer, cancer treatments, and environmental factors can increase this. Chromosome abnormality is commonplace in human embryos and one reason for the development of the controversial preimplantation genetic screening CPOS). Factors such as embryo quality and maternal age are cornmon correlates. Appropriate nucleus positioning of chromosome territories is also though to be indicative of a "healthy" nucleus with aberrations in such nuclear organization associated with disease. The purpose of this study was to provide insight into the relationship between chromosome copy number, nuclear organization and various aetiological factors in human sperm and early stage embryos. Specifically. • To investigate the nuclear positioning oftelomeric and sub telomeric region in sperm cells and test the hypothesis that such organisation is altered in infertile males. • To investigate the nuclear positioning of centromeric and locus specific regions of 5 chromosomes in sperm cells from males undergoing chemotherapeutic treatment for testicular cancer and Hodgkin's lymphoma and test the hypothesis that either the cancer, or its treatment significantly alters patterns of nuclear organization. • To analyse FISH based PGS and "follow up" in 250 treatment cycles to investigate levels of aneuploidy false negative and positive results, also well as effects of different indications such as maternal age. • To investigate the levels of aneuploidy for all 24 chromosomes using a newly developed multicolour FISH technique. To test hypotheses that factors e.g. maternal age and embryo morphology significantly effect levels, and that day 3 and day 5 results are concordant. • To assess levels nuclear organisation of human embryos for loci on all 24 chromosomes and their relationship to maternal age, day 3 and day 5 embryo morphology. Overall, results provide some evidence for differences in nuclear organisation in infertile males compared to controls for telomeric but not sub-telorneric loci. Effects of cancer (testicular cancer and Hodgkin's lymphoma) and chemotherapy were subtle at best with one testicular cancer patient showing a significant difference compared to controls. In embryos, monosomy appeared more common that trisomy and effects of maternal age and embryo quality were apparent when a small subset of chromosomes were analysed. Similar analysis with a 24 FISH assay confirmed monosomy/trisomy ratios however failed to show significant relationship with maternal age and embryo morphology, thereby raising questions about the reliability of the technique. Finally comparison of various parameters and nuclear organization revealed consistent alterations of the position of specific centromeres (e.g. for chromosomes 3 and 4). In conclusion, FISH is now clearly old technology for PGS but has great potential for the analysis of mosaicism and nuclear organisation.

The chromosome numbers of the eight following species of freshwater diaptomid copepods were examined to elucidate relationships between species: Aglaodiaptomus clavipes, A. leptoups, Leptodiaptomus ashlandi, A. minutus, A. sicilis, A. siciloides, Skistodiaptomus oregonensis, and S. pallidus. The specimens evaluates were collected from various lakes in Wisconsin including Lake Michigan. Squash mounts were prepared from female individuals for microscopic evaluation. Comparisons of chromosome numbers and chromosome morphology indicated that the species considered are not as closely related as might be suspected based on external morphological considerations. The chromosome numbers varied greatly between species and no consistant numbers within subgenera were observed, substantiating the idea that the species are clearly well separated phylogenetically. A technique for preparing chromosome squash mounts from formalin preserved specimens in presented.Ball State UniversityMuncie, IN 47306

DNA amplification is an important mechanism of tumor progression that allows cancer cells to up-regulate expression of critical genes such as oncogenes. Recent studies using comparative genomic hybridization revealed increased DNA copies on chromosome 20q in seven melanoma cell lines and eight archival metastatic melanoma lesions. We performed FISH analysis of metaphase spreads in 13 melanoma cell lines and nine primary melanoma specimens using a variety of probes specific for chromosome 20. All 13 cell lines (100%) and 8/9 primary tumors (89%) showed extra copies of chromosome 20 relative to tumor ploidy. Additionally, 6/14 cell lines (43%) and 2/8 primary tumors (25%) showed translocated chromosome 20 material. Cytological evidence for gene amplification was found in one of the 13 cell lines with an add(20)(p13). These data suggest that over-representation of a gene(s) important for melanoma pathogenesis occurs on the chromosome 20 long arm.