Добірка наукової літератури з теми "Taiwanensis"

Frequent earthquakes, monsoon torrential rains and typhoons cause severe landslides and soil erosion in Taiwan. Hibiscus taiwanensis, Macaranga tanarius, and Mallotus paniculatus are major pioneer tree species appearing on landslide-scarred areas. Thus, these species can be used to restore the self-sustaining native vegetation on forest landslides, to control erosion, and to stabilize slope. However, their growth performance, root traits and biomechanical properties have not been well characterized. In this study, root system and root traits were investigated using the excavation method, and biomechanical tests were performed to determine the uprooting resistance, root tensile strength and Young’s modulus of 1-year-old Hibiscus taiwanensis, Macaranga tanarius, and Mallotus paniculatus seedlings. The results reveal that relative to H. taiwanensis, M. tanarius and M. paniculatus seedlings had significantly larger root collar diameter, longer taproot length, higher root biomass, higher root density, higher root length density, heavier root mass, larger external root surface area, higher root tissue density, larger root volume, longer total root length, and a higher root tip number. Additionally, the height of M. paniculatus seedlings was significantly higher than those of H. taiwanensis and M. tanarius. Furthermore, the uprooting resistance and root tensile strength of M. paniculatus seedlings was significantly higher than those of H. taiwanensis and M. tanarius. Young’s modulus of M. paniculatus and M. tanarius seedlings was also significantly higher than that of H. taiwanensis. These growth characteristics and biomechanical properties demonstrate M. paniculatus and M. tanarius are superior than H. taiwanensis, considering growth performance, root anchorage capability, tensile strength and Young’s modulus. Taken as a whole, the rank order for species selection of these pioneer species for reforestation comes as: M. paniculatus M. tanarius H. taiwanensis. These results, along with knowledge on vegetation dynamics following landslides, allow us to better evaluate the effect of selective removal management of pioneer species on the resilience and sustainability of landslides.

The Gram-negative bacterium Pseudomonas taiwanensis is a novel bacterium that uses shrimp shell waste as its sole sources of carbon and nitrogen. It is a versatile bacterium with potential for use in biological control, with activities including toxicity toward insects, fungi, and the rice pathogen Xanthomonas oryzae pv.oryzae (Xoo). In this study, the complete 5.08-Mb genome sequence of P. taiwanensis CMS was determined by a combination of NGS/Sanger sequencing and optical mapping. Comparison of optical maps of seven Pseudomonas species showed that P. taiwanensis is most closely related to P. putida KT 2400. We screened a total of 11,646 individual Tn5-transponson tagged strains to identify genes that are involved in the production and regulation of the iron-chelator pyoverdine in P. taiwanensis, which is a key anti-Xoo factor. Our results indicated that the two-component system (TCS) EnvZ/OmpR plays a positive regulatory role in the production of pyoverdine, whereas the sigma factor RpoS functions as a repressor. The knowledge of the molecular basis of the regulation of pyoverdine by P. taiwanensis provided herein will be useful for its development for use in biological control, including as an anti-Xoo agent.

Ficus carica L. is one of the earliest cultivated fruit trees, and figs are a typical fruit of the Mediterranean diet and traditional medicine as well. In recent years, a new pest, the black weevil Aclees taiwanensis Kȏno, 1933 (Coleoptera: Curculionidae) native to Asia, has been recorded in France and Italy. Aclees taiwanensis causes the rapid death of the fig tree by its larvae that dig alimentation galleries in the trunk and surface roots, compromising the phloem flux. In Italy, from 2005, the year of the first detection of A. taiwanensis, the fig production has nearly halved, decreasing from 20.09 t to 10.65 t. To date, no specific EU regulation has been applied to prevent the A. taiwanensis spread, and we can reasonably expect a rapid diffusion of this pest all over the Mediterranean area. To avoid the loss of the Mediterranean fig orchards, effective strategies to detect and control the black weevil are required. Such strategies need a detailed knowledge of A. taiwanensis distribution, biology, and physiology. This paper updates the known distribution of this species in Southern Europe, using a citizen science approach, and describes, under laboratory and field conditions, its main biological traits.

A new sparid species, Acanthopagrus taiwanensis, is described on the basis of six specimens that were previously misidentified as A. berda (Forsskål, 1775), collected from Tung-kang, southwestern Taiwan. Acanthopagrus taiwanensis and A. berda are similar in overall appearance, both with deep bodies. However, A. taiwanensis differs from the latter in having a more rounded body, broadly rounded anteriormost head squamation with around 10 somewhat smaller scales anteriorly, 3 or 4 cheek scale rows, thin upper and lower lips, older individuals with a ridge on dorsal profile in front of eye and upper profile of head evenly convex, head and body black with sharply contrasting white area ventrally, a dark spot at upper base of pectoral fins, and flat molar teeth. In contrast, A. berda has a deeper body, broadly rounded anteriormost head squamation with around 20 small scales anteriorly, 5 or 6 cheek scale rows, thick upper and lower lips, larger individuals with a weak ridge in profile in front of eye and concave snout profile, head and body silvery gray, no black spot at upper base of pectoral fins and somewhat pointed molar teeth. Older individuals of A. berda also develop a strong concavity of the ventral edge of the first two infraorbitals above the posterior part of upper jaw, while the edge is relatively straight or weakly concave in A. taiwanensis. We discuss the nominal species that have been placed in synonymy with A. berda and contrast A. taiwanensis with similar congeners.

A new isolate of the entomopathogenic nematode, Steinernema taiwanensis n. sp., was isolated from soil in Pingtung County, Taiwan. This new species could be characterized and distinguished from other related species by its morphological characters, morphometrics, and phylogenetic analysis. The body length and distance from anterior end to nerve ring of infective juveniles is 1012 (983–1045) µm and 124 (120–127) µm, lateral field formula 2, 6, 7, 8, 2, and the tail length 90 (79–96) µm without dorsal constriction in tail region. The first generation males of S. taiwanensis n. sp. are characterized by spicule shape, smooth blade tip, 23 genital papillae (11 pairs and 1 single papilla), spicule length of 94 (89–99) µm and gubernaculum length of 68 (65–70) µm. Females from the first generation of S. taiwanensis n. sp. have no epiptygmata and a slightly developed post-anal swelling. Phylogenetic analysis of ITS and D2D3 regions of rDNA showed that S. taiwanensis n. sp. belongs to the Longicaudum-clade and comprises a monophyletic group with S. guangdongense and S. longicaudum. The new isolate is described as a novel species according to morphological and phylogenetic analyses.

Polyhydroxyalkanoates (PHA) are microbial polyesters that have recently come to the forefront of interest due to their biodegradability and production from renewable sources. A potential increase in competitiveness of PHA production process comes with a combination of the use of thermophilic bacteria with the mutual use of waste substrates. In this work, the thermophilic bacterium Tepidimonas taiwanensis LMG 22826 was identified as a promising PHA producer. The ability to produce PHA in T. taiwanensis was studied both on genotype and phenotype levels. The gene encoding the Class I PHA synthase, a crucial enzyme in PHA synthesis, was detected both by genome database search and by PCR. The microbial culture of T. taiwanensis was capable of efficient utilization of glucose and fructose. When cultivated on glucose as the only carbon source at 50 °C, the PHA titers reached up to 3.55 g/L, and PHA content in cell dry mass was 65%. The preference of fructose and glucose opens the possibility to employ T. taiwanensis for PHA production on various food wastes rich in these abundant sugars. In this work, PHA production on grape pomace extracts was successfully tested.

Bacterial symbionts present in the indeterminate-type nitrogen (N)-fixing nodules of Mimosa pudica grown in North and South India showed maximum similarity to Ralstonia taiwanensis on the basis of carbon-source utilization patterns and 16S rDNA sequence. Isolates from the nodules of M. pudica from North India and South India showed identical ARDRA (Amplified Ribosomal DNA Restriction Analysis) patterns with Sau3AI and RsaI, but AluI revealed dimorphy between the North Indian and South Indian isolates. Alignment of 16S rDNA sequences revealed similarity of North Indian isolates with an R. taiwanensis strain isolated from M. pudica in Taiwan, whereas South Indian isolates showed closer relatedness with the isolates from Mimosa diplotricha. Alignment of nifH sequences from both North Indian and South Indian isolates with that of the related isolates revealed their closer affinity to α-rhizobia, suggesting that nif genes in the β-rhizobia might have been acquired from α-rhizobia via lateral transfer during co-occupancy of nodules by α-rhizobia and progenitors of R. taiwanensis, members of the β-subclass of Proteobacteria. Immunological cross-reaction of the bacteroid preparation of M. pudica nodules showed strong a positive signal with anti-dinitrogenase reductase antibody, whereas a weak positive cross-reaction was observed with free-living R. taiwanensis grown microaerobically in minimal medium with and without NH4Cl. In spite of the expression of dinitrogenase reductase under free-living conditions, acetylene reduction was not observed under N-free conditions even after prolonged incubation.Key words: symbiotic nitrogen fixation, Mimosa pudica, rhizobia, phylogeny, 16S rDNA, nifH, Ralstonia taiwanensis.

Rhizobia, the nitrogen-fixing symbionts of legumes, are polyphyletic bacteria distributed in many alpha- and beta-proteobacterial genera. They likely emerged and diversified through independent horizontal transfers of key symbiotic genes. To replay the evolution of a new rhizobium genus under laboratory conditions, the symbiotic plasmid of Cupriavidus taiwanensis was introduced in the plant pathogen Ralstonia solanacearum, and the generated proto-rhizobium was submitted to repeated inoculations to the C. taiwanensis host, Mimosa pudica L. This experiment validated a two-step evolutionary scenario of key symbiotic gene acquisition followed by genome remodeling under plant selection. Nodulation and nodule cell infection were obtained and optimized mainly via the rewiring of regulatory circuits of the recipient bacterium. Symbiotic adaptation was shown to be accelerated by the activity of a mutagenesis cassette conserved in most rhizobia. Investigating mutated genes led us to identify new components of R. solanacearum virulence and C. taiwanensis symbiosis. Nitrogen fixation was not acquired in our short experiment. However, we showed that post-infection sanctions allowed the increase in frequency of nitrogen-fixing variants among a non-fixing population in the M. pudica–C. taiwanensis system and likely allowed the spread of this trait in natura. Experimental evolution thus provided new insights into rhizobium biology and evolution.

Bacteriocins are functionally diverse toxins produced by most microbes and are potent antimicrobial peptides (AMPs) for bacterial ghosts as next generation vaccines. Here, we first report that the AMPs secreted from Lactobacillus taiwanensis effectively form ghosts of pathogenic bacteria and are identified as diverse bacteriocins, including novel ones. In detail, a cell-free supernatant from L. taiwanensis exhibited antimicrobial activities against pathogenic bacteria and was observed to effectively cause cellular lysis through pore formation in the bacterial membrane using scanning electron microscopy (SEM). The treatment of the cell-free supernatant with proteinase K or EDTA proved that the antimicrobial activity is mediated by AMPs, and the purification of AMPs using Sep-Pak columns indicated that the cell-free supernatant includes various amphipathic peptides responsible for the antimicrobial activity. Furthermore, the whole-genome sequencing of L. taiwanensis revealed that the strain has diverse bacteriocins, confirmed experimentally to function as AMPs, and among them are three novel bacteriocins, designated as Tan 1, Tan 2, and Tan 3. We also confirmed, using SEM, that Tan 2 effectively produces bacterial ghosts. Therefore, our data suggest that the bacteriocins from L. taiwanensis are potentially useful as a critical component for the preparation of bacterial ghosts.

La symbiose qui s'établit entre les légumineuses et les bactéries appelées rhizobia est un processus complexe qui aboutit à la formation d'un nouvel organe végétal, le nodule, dans lequel les bactéries internalisées (bactéroïdes) fixent l'azote atmosphérique au profit de leur hôte. Les rhizobia ne constituent pas un groupe taxonomique homogène. Ils appartiennent à une quinzaine de genres dispersés au sein des α- and ß-protéobactéries. Les rhizobia auraient évolué à partir du transfert horizontal de gènes essentiels à la symbiose, suivi d'une réorganisation du génome d'accueil sous pression de sélection de la plante permettant une activation et/ou optimisation du potentiel symbiotique acquis. Ce scénario évolutif a été reproduit en laboratoire par une approche d'évolution expérimentale. Le plasmide symbiotique du symbiote de Mimosa pudica, Cupriavidus taiwanensis LMG19424, a été introduit dans la bactérie pathogène de plante Ralstonia solanacearum GMI1000. A partir de cette bactérie chimère 18 lignées parallèles ont été évoluées par des cycles successifs d'inoculation à M. pudica et ré-isolation des bactéries des nodules. Après 16 cycles d'évolution, trois observations ont été faites : i) les bactéries évoluées ne fixent pas l'azote et l'évolution vers le mutualisme n'est donc pas achevée à ce stade, ii) un gène de fonction inconnue semble important pour l'infection intracellulaire, et iii) les mutations permettant l'acquisition et/ou l'amélioration de l'infection des cellules du nodule semblent également améliorer la nodulation. Afin d'identifier les conditions favorables à l'émergence du mutualisme dans l'expérience d'évolution et potentiellement dans la nature, nous avons analysé la dynamique spatio-temporelle de deux sous-populations quasi isogéniques de C. taiwanensis, l'une fixatrice d'azote (Fix+) et l'autre non fixatrice (Fix-), au cours du processus symbiotique avec M. pudica. Nous avons observé une dégénérescence précoce et sélective des Fix-, y compris lorsqu'ils partagent un même nodule avec des Fix+, et établit la cinétique d'expansion des Fix+ au cours du temps. A partir d'un modèle mathématique et de validations expérimentales, nous avons prédit que de rares Fix+ envahiraient une population majoritairement Fix- au cours de cycles successifs de nodulation avec une probabilité fonction de la taille initiale de l'inoculum, du nombre de plantes inoculées et de la longueur des cycles. Par la suite nous avons étudié le rôle d'un gène du plasmide symbiotique de C. taiwanensis, dont la délétion dans l'une des lignées était responsable d'un défaut d'infection intracellulaire. Nous avons montré que ce gène, appelé noeM, est un gène de nodulation impliqué dans la biosynthèse de facteurs Nod atypiques où le sucre réducteur est ouvert et oxydé. noeM est principalement détecté dans des isolats de plantes appartenant à la tribu des Mimoseae, et particulièrement chez les souches capables de noduler M. pudica. Les gènes noeM forment un clade phylogénétique à part et spécifique des rhizobia. Un mutant ΔnoeM de C. taiwanensis s'est avéré affecté pour la nodulation de M. pudica, confirmant son rôle dans la symbiose avec cette légumineuse. Enfin, l'analyse cytologique détaillée de l'infection racinaire de M. pudica par C. taiwanensis et quelques souches de R. solanacearum portant une mutation adaptative de l'infection intracellulaire a été initiée, afin d'analyser l'impact de ces mutations sur les étapes symbiotiques précoces
The symbiosis between legumes and bacteria, known as rhizobia, is a complex process resulting in the formation of a novel plant organ, the nodule, in which internalized bacteria (bacteroids) fix nitrogen to the benefit of the host plant. Rhizobia do not form a homogeneous taxonomic group. They belong to a dozen of genera scattered within α- and ß-proteobacteria. Rhizobia may have evolved from horizontal transfer of key symbiotic genes, followed by genome remodeling under plant selection pressure, allowing the activation and/or optimization of the acquired symbiotic potential. This evolutionary scenario is being replayed in the laboratory using an experimental evolution approach. The symbiotic plasmid of the Mimosa pudica symbiont, Cupriavidus taiwanensis LMG19424, was introduced into the plant pathogen Ralstonia solanacearum GMI1000. 18 parallel lineages were derived from this chimeric ancestor using serial cycles of inoculation with M. pudica and re-isolation of bacteria from the nodules. After 16 cycles of evolution, three observations were done: i) the evolved bacteria do not fix nitrogen and evolution towards mutualism is not completed, ii) a gene of unknown function seems to be involved in intracellular infection and iii) the mutations that allow and/or improve intracellular infection also improve nodulation capacity. To determine conditions that favor the emergence of mutualism in the laboratory and possibly in nature, we analyzed the spatio-temporal dynamics of two quasi-isogenic sub-populations of C. taiwanensis, one nitrogen-fixing (Fix+) and the other not (Fix-), along their symbiotic process with M. pudica. We observed an early degenerescence of Fix- bacteroids, even when they share a nodule with Fix+, and established the kinetics of Fix+ expansion along time. Using mathematical modeling and experimental validations, we predicted that rare Fix+ will invade a population dominated by non-fixing bacteria during serial nodulation cycles with a probability that is function of initial inoculum, plant population size and nodulation cycle length. Then, we studied the role of a C. taiwanensis symbiotic plasmid gene, whose deletion in one lineage was responsible of intracellular infection defect. We showed that this gene, called noeM, is a novel nodulation gene involved in the biosynthesis of atypical Nod factors where the reducing sugar is open and oxidized. noeM was mostly found in isolates of the Mimoseae tribe, especially in all strains able to nodulate M. pudica. The noeM genes form a separate phylogenetic clade containing only rhizobial genes. A noeM deletion mutant of C. taiwanensis was affected for the nodulation of M. pudica confirming the role of noeM in the symbiosis with this legume. Last, we initiated the detailed cytological analysis of M. pudica root infection by C. taiwanensis and a few strains bearing adaptive mutations for intracellular infection, in order to analyze the effect of these mutations on early symbiotic stages

La 1ere partie de la these concerne la caracterisation de 2 nouvelles especes de spiroplasmes isoles de moustiques. Les souches ar-1343 et ct-1, distinctes serologiquement des autres spiroplasmes connus, ont ete etudiees selon les criteres du comite sur la taxonomie des mollicutes pour la description d'une espece. Nous avons demontre leur appartenance a la classe des mollicutes a cause de leur membrane unitaire, de la morphologie de leurs colonies et leur capacite a traverser les membranes de filtration, leur appartenance a la famille des spiroplasmataceae a cause de leur morphologie helicoidale et leur motilite. Leur croissance exigeait du cholesterol; les 2 souches fermentaient le glucose et la souche ar-1343 hydrolysait l'arginine. La composition en bases (g plus c) de l'adn des souches ar-1343 et ct-1 etait respectivement de 30 plus ou moins 1 et de 25 plus ou moins 1 mole pour cent. Nous avons nomme les souches ar-1343 et ct-1 spiroplasma sabaudiense et spiroplasma taiwanense respectivement. La 2eme partie concerne la classification du groupe 16 des spiroplasmes. Ce groupe heterogene est compose de 17 souches isolees en france et aux usa. Toutes ces souches ont ete comparees par 2 methodes serologiques et par analyse electrophoretique de leurs proteines en gel de polyacrylamide. Cinq d'entre elles ont ete selectionnees afin de comparer leurs adn par hybridation adn-adn et apres hydrolyse par des enzymes de restriction. Nous avons propose que le groupe 16 des spiroplasmes doit divise en 3 sous-groupes

碩士
國立臺灣師範大學
生物學系
75
In the leaves (but not corms) of the submerged aquatic plant Isoetes taiwanensis, both in the field and greenhouse, malic acid concentration fluctuates from 10-13mg/gfw in the morning to 1-3 mg/gfw in the evening. Associated with this is a change in pH (a. m. pH 3-4 vs. p. m. pH 5-6) and titrable acidity (220-20 ueq/gfw change in acidity between morning and evenign) of the plant extract, It is obvious that Isoetes taiwanensis is a CAM plant. The change of malic acid and titrable acidity are decreased when the leaves emerged. 　　It is suggested that CAM in Isoetes taiwanensis may be related to the lower availability of CO2 for photosynthesis during the day than during the night, and short time high intensity light. 　　The stomata are closed when the leaf submerged; and open when the leaf emerged. After 2 hours the leaf expose to air, the open ratio is 100%; but when the leaf submerged again, the closed ratio is only about 85% after 10 hours. 　　We find the movement of guard cells are controlled by the subsidary cells from the S. E. M. and paraffin method''s observations.

碩士
高雄醫學大學
醫學研究所
82
Ascogregarina taiwanensis, originally reported from the mosquito Aedes albopictus collected in Taiwan, belongs to the Phylum Apicomplexa, the Class Sporozoa, the Order Gregarina, the suborder Aseptatina and the Family Lecudinidae in taxonomy. In this study, ultrastructures in various stages of the parasite and its life cycle in the mosquito host were investigated by using light and electron microscopy. The result showed that sporozoites were soon releasedfrom ingested oocysts in the lumen of the midgut and then penetrated into the epithelium, forming the intracellular stage. Subsequently, the parasite left the epithelium and develope into the extracellular stage trophozoite in 2 days. The fine structures of A. taiwanensis, intracellular or extracellular, showed that the surface of the parasite consisted of two distinct layers. The outer layer was always thicker than the inner one. There usually were groups of small dots, called as subpellicular fibrils, right under the inner membrane. Fibrils in each group appeared to be parallel. The cytoplasma of the parasite can be divided into two parts. The outer part-ectoplasma contained relatively fine granules while the contents of the inner part- endoplasma was full of rough granules. In fact, many organelles including endoplasmic reticulum, mitochondria, ribosomes and dense granules can be seen in both parts of the cytoplasma. However, some other organelles such as vacuoles, droplets and paraglycogens appeared only in the ectoplasma. Usually, there is a mitochondria zone in the space between the protomerite and the deutomerite. As a usual, the late stage of the trophozoites migrated into the Malpighian tubules when the mosquito pupated. One of interesting findings in this study is that the trophozoite twisted off to remove most body except the portion containing the nucleus. The resulting spherical or elliptic gametes subsequently paired up to become the early stage of the gametocyst. A number of oocysts were then matured in each gametocyst before they were expelled with excreta into the breeding site. The ultrastructural studies showed that a septum was formed in the middle of the newly-formed, i.e., primary gametocyst. Subpellicular fibrils can be seen on both sides of the multi-layered septum, indicating the septum was derived from fusing of two parasite surfaces. It seems that the capsule surrounding the early gametocyst tended to fuse with surface membrane of the parasites which were conjugating, resulting in a thicker outer membrane. The septum subsequently disappeared, leading to form a more mature gametocyst containing fine granules. The contents of the developing gametocyst later became relatively rough, in which a mass of cytoplasma containing a number of vacuoles were formed. Later on, the cytoplasmic mass cleavaged into many small pieces. Each piece was finally transformed into an individual oocyst. As a matter of fact, the oocyst with defined shape was formed 2 days post pupation. According to the observations in this study, the gametocyst of the 3rd day pupae was full of numerous oocysts which were released when the gametocyst were pressed. In consequence, the oocyst further matured to be a lemon shape with plugs on both ends. During the late developing stage, vacuoles and granules within the oocyst disappeared gradually. The complete mature oocyst containing 8 sporozoites was usually formed 2 days after emergence. Ultrastructurally, the distinct organelles of the sporozoite included a monolayered-surface membrane, 2 preconid polar rings and one polar ring in its anterior portion. In addition, subpellicular microtubules, including an internal tubules, origined from the polar ring was pretty close to rhopties. In conclusion of the life cycle study, a sexual reproductive process distinguished from those occurring in other apicomplexan arised. Eventually, the "pseudoconjugatio", which has been thought to occur before gametes were formed, was a true conjugation in this gregarine parasite. Perhaps this reproduction behavior isadaptable to most of the related species.

碩士
國立臺灣師範大學
生物研究所
90
Sphenomorphus taiwanensis is an endemic species of Taiwan. It was distributed above 2000 m attitude. Currently, most phylogeographic studies focused on lower attitude species. To high attitude species,living in high mountains was like living in an isolation island. The geological isolation may influence the population genetic structure of S. taiwanensis. Cytochrome b (Cyt b) and cytochrome oxidase c subunit 1 (COX1) were used as genetic markers to analysis the phylogeography of S. taiwanensis. The partial sequences were determined in 89 individuals. 56 and 48 haplotype were identified. The maximum pairwise genetic distance between individuals within population was 10.6% (Cyt b) and 10.4% (COX1). The maximum pairwise genetic distances between individuals between populations were 16.6% (Cyt b) and 11.2% (COX1). The mean pairwise genetic distance within population were 0.4~9.8% (Cyt b) and 0~5.7% (COX1). The mean pairwise genetic distance between populaitons were 3.2~13.9% (Cyt b) and 1.6~10.4% (COX1). We found that the intraspecies genetic variation of S. taiwanensis was larger than other species. The gene flow index indicated that the gene flows among populations were hindered. It indicated that the differentiation level among populations was high, but was not consistent with isolation by distance model. We found the gene flows between Hsuehshan population and other populations were hindered. We thought Hsuehshan population was an special isolation population. Phylogenetic trees were constructed by neighbor-joining (NJ) and maximum parsimony (MP) methods using S. incognitus and S. indicus as the outgroups indicated that S. taiwanensis can be separated into nine major lineages with high bootstrap value. Some lineages were allopatric, others were sympatric. The lineages’ distribution was not consistent with the geological distribution of populations. Some populations only had one lineage, included Hsuehshan, Tahsuehshan, Hohuanshan, Alishan, Yakou population. Kuanwu and Taipingshan population had two lineages, Tatachia population had three lineages, and Nanhu population had four lineages. The genetic diversity of Nanhu population was very high. The reason of that there were high intraspecies genetic variation of S. taiwanensis may be multiple invasion or refuge effect or radiation evolution.

碩士
國立臺灣大學
森林學研究所
93
Maackia taiwanensis Hoshei et Ohashi is an endemic species to Taiwan which belong to the Fabaceae, Faboideae. Trees are deciduous. Bisexual flowers are produced from early August to late August. The pods are maturing in December. Inflorescence primordia are formed at shoot apices in mid April. The primordia of calyx occur in late April. The primordial of petal, stamen and pistl occur successively from early June to late June. Calyx 5-lobed；petal 5, consisting of one standard, two wing and two keel-petal. Stamens 10, two whorls and anther are tetrasporangiate. The pistil is mono-carpellary with gynophore. Young anthers are composed of a protoderm and a central cell mass in early July. The anther wall layers consist of an epidermis, one layered endothecium, two middle layers and a tapetum of one layer. The development of anther wall layer belongs to the basic type. The tapetum is of the glandular type. Pollen mother cells undergo meioses through simultaneous cytokinesis and give rise to tetrads of microspores, which are tetrahedrally arranged. Mature pollen grains are 2-celled, globose, 3-colporate and 15~20μm in diameter. Anther dehiscence is longitudinal. The pistil with 2 to 5 ovules on a marginal placentation. Ovules are campylotropous, bitegamic. The outer integument is composed of 3 to 6 layers of cells in thickness, while the inner integument is of 2 layers of cells. The inner integument is degenerated during the seeds development. The megaspore mother cell is located 4-6 layers of cells beneath the epidermis at the nucellus top end. So it defined as crassinucellate. The megaspore mother cell divides transversally to form a linear megaspore tetrad. The megaspore at the chalazal end develops into the embryo sac mother cell. The development of embryo sac is Polygonum type. The two polar nuclei fuse before fertilization and the the three antipodal cells degenerate soon after fertilization. Multi-embryo sac might occasionally occur in an ovule. The endosperm deveolops through nuclei multiplication and is degenerated at seed maturing. Seeds consist of an embryo without endosperm.

On a global basis, trace-metal pollution is one of the most pervasive environmental problems. It is particularly difficult to prevent or clean up because the metals are toxic in their elemental form and cannot be decomposed. Bioremediation has been shown to be a powerful system for heavy metal pollution clean up and prevention. In this work, we characterized the cadmium (Cd)-resistant bacteria isolated from rice field soil downstream from zinc (Zn) mineralized area which the owners were contaminated at high level of cadmium content in their blood (>10 μgCd/g creatinine). We found that all 24 isolated bacteria tolerated toxic Cd concentrations (2,500 μM). In order to determine whether the Cd toxicity affected the growth of isolated bacteria, we grew the isolated bacterial cells in the absence and presence of toxic concentrations of CdCl2 (500 μM). In the absence of Cd, all isolated bacterial cells grew slightly better than in the presence of toxic concentrations of Cd. In addition, the Cd binding capacity of all isolated bacteria were very high, ranging from 6.38 to 9.38 log[Cd(atom)]/cell when grown in the presence of 500 μM CdCl2. Furthermore, the stability of Cd-bacteria complex of all isolated bacteria was affected by 1mM EDTA. When grown in the presence of 500 μM CdCl2, Cd-resistant isolates S2500-6, -8, -9, -15, -17, -18, -19, and -22 increasingly produced proteins containing cysteine (SH-group) (from 1.3 to 2.2 times) as well as 11 isolates of Cd-resistant bacteria, including S2500-1, -2, -3, -5, -6, -8, -9, -11, -16, -20, and -21, increasingly produced inorganic sulfide (1.5 to 4.7 times). Furthermore, the Sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy studies indicated that Cd-resistant isolated S2500-3 precipitated amounts of cadmium sulfide (CdS), when grown in the presence of 500 μM CdCl2. The results suggested that these Cd-resistant bacteria have potential ability to precipitate a toxic soluble CdCl2 as nontoxic insoluble CdS. Interestingly, Cd-resistant bacteria isolated S2500-3, -8, -9,and -20 increased cadmium tolerance of Thai jasmine rice (Kao Hom Mali 105) when grown in the presence of 200 μM CdCl2. These 4 isolates also decreased cadmium concentration accumulation in Kao Hom Mali 105 plant at 61, 9, 6, and 17%, respectively when grown in the presence of 200 μM CdCl2. They were identified by 16S rDNA sequence analysis and classified as Cupriavidus taiwanensis (isolate S2500-3) and Pseudomonas aeruginosa (isolates S2500-8, -9, and -20).