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排序方式: 共有134条查询结果,搜索用时 15 毫秒
121.
The semi-aquatic freshwater earthworm genus Glyphidrilus Horst, 1889 from Thailand was investigated based on extensive recent collecting. The species in this genus were characterized by their external and internal morphological characters of the location of wings, genital openings, genital organ structures and their locations, as well as the dimensions of body length and number of segments. Several type specimens were compared with both previous and newly collected materials. Ten new species are described from several river systems in Thailand; as Glyphidrilus borealis
sp. n., Glyphidrilus chaophraya
sp. n., Glyphidrilus chiensis
sp. n., Glyphidrilus huailuangensis
sp. n., Glyphidrilus kratuensis
sp. n., Glyphidrilus quadratus
sp. n., Glyphidrilus trangensis
sp. n., Glyphidrilus wararamensis
sp. n., Glyphidrilus vangthongensis
sp. n. and Glyphidrilus vesper
sp. n. Each species is endemic to a single river system. All 26 previously described species are re-described, and eight lectotypes have been designated. An identification key and a morphological comparison summary are provided. 相似文献
122.
123.
We examined allozyme variation in two camaenid tree snails, Amphidromus atricallosus and A. inversus, across two principal regions of Thailand and from Singapore, plus for A. inversus, one site in peninsular Malaysia. Using horizontal starch gel electrophoresis, 13 allozyme loci (11 polymorphic) were screened for A. atricallosus and 18 (5 polymorphic) for A. inversus. Heterozygosity was higher in A. atricallosus (Hexp=0.018-0.201, mean=0.085) than in A. inversus (Hexp=0-0.023, mean= 0.002). Genetic heterogeneity among samples was higher in A. inversus (Fst=0.965) than in A. atricallosus (Fst=0.781). Within A. atricallosus, populations were more differentiated in southern Thailand (Fst=0.551) than in eastern Thailand (Fst=0.144). The high Fst and low Hexp in populations of A. inversus suggest that this species is likely to have experienced a series of strong bottlenecks, perhaps occurring chiefly on offshore continental-shelf islands. The low Fst values of A. atricallosus in eastern Thailand suggest frequent gene flows among populations in this region. The southern and eastern samples of A. atricallosus exhibited fixed allele differences at four loci and great genetic distance (Nei's D=0.485-0.946), suggesting that these two samples may actually represent, or else be evolving into, separate species. 相似文献
124.
Nattawadee Nantarat Chirasak Sutcharit Piyoros Tongkerd Jonathan Ablett Fred Naggs Somsak Panha 《ZooKeys》2014,(411):1-56
The collection of land caenogastropod snails in the genus Cyclophorus Monfort, 1810 housed in the Natural History Museum, London (NHM), includes 52 type lots. Lectotypes have been designated for 43 available species-level names to stabilize existing nomenclature, two previously designated lectotype, two holotypes, one paratype, one syntype, one possible syntype and two paralectotypes are also listed. A complete catalogue of the Cyclophorus types in NHM, London is provided for the first time. 相似文献
125.
Mutamba JT Svilar D Prasongtanakij S Wang XH Lin YC Dedon PC Sobol RW Engelward BP 《DNA Repair》2011,10(12):1282-1293
Inflammation associated reactive oxygen and nitrogen species (RONs), including peroxynitrite (ONOO−) and nitric oxide (NO), create base lesions that potentially play a role in the toxicity and large genomic rearrangements associated with many malignancies. Little is known about the role of base excision repair (BER) in removing these endogenous DNA lesions. Here, we explore the role of X-ray repair cross-complementing group 1 (XRCC1) in attenuating RONs-induced genotoxicity. XRCC1 is a scaffold protein critical for BER for which polymorphisms modulate the risk of cancer. We exploited CHO and human glioblastoma cell lines engineered to express varied levels of BER proteins to study XRCC1. Cytotoxicity and the levels of DNA repair intermediates (single-strand breaks; SSB) were evaluated following exposure of the cells to the ONOO− donor, SIN-1, and to gaseous NO. XRCC1 null cells were slightly more sensitive to SIN-1 than wild-type cells. We used small-scale bioreactors to expose cells to NO and found that XRCC1-deficient CHO cells were not sensitive. However, using a molecular beacon assay to test lesion removal in vitro, we found that XRCC1 facilitates AAG-initiated excision of two key NO-induced DNA lesions: 1,N6-ethenoadenine and hypoxanthine. Furthermore, overexpression of AAG rendered XRCC1-deficient cells sensitive to NO-induced DNA damage. These results show that AAG is a key glycosylase for BER of NO-induced DNA damage and that XRCC1's role in modulating sensitivity to RONs is dependent upon the cellular level of AAG. This demonstrates the importance of considering the expression of other components of the BER pathway when evaluating the impact of XRCC1 polymorphisms on cancer risk. 相似文献
126.
The millipede genus Kronopolites currently comprises 11 species, including a new species from northern Laos: Kronopolites
lunatus
sp. n. The generic diagnosis is updated, a key given to all known species, and their distributions are mapped. 相似文献
127.
128.
129.
Ting Hui Ng Phiraphol Chusongsang Yupa Chusongsang Somsak Panha 《Molluscan research.》2019,39(2):140-147
ABSTRACTFour decades after its publication, Rolf A.M. Brandt’s 1974 monograph on the non-marine molluscs of Thailand remains the main authority on freshwater and estuarine species for Southeast Asia and includes up to 165 new species of snails and bivalves described by Brandt and colleagues in the same book and preceding publications. All the holotypes are lodged at the Forschungsinstitut und Naturmuseum Senckenberg in Germany, and are largely inaccessible to Thai and other Southeast Asian researchers, who rely heavily on the Brandt collection as a key reference. Paratypes were, however, donated to various other collections, including some in Thailand. We present the first catalogue of 45 paratypes of gastropods of the Brandt collection, described from Thailand, Laos and Cambodia, which are lodged at the Faculty of Tropical Medicine, Mahidol University, Thailand. 相似文献
130.
Laksana Kantama Supaporn Junbuathong Janejira Sakulkoo Hans de Jong Somsak Apisitwanich 《Molecular breeding : new strategies in plant improvement》2013,31(4):815-827
Inter- or intraspecific hybridization is the first step in transferring exogenous traits to the germplasm of a recipient crop. One of the complicating factors is the occurrence of epigenetic modifications of the hybrids, which in turn can change their gene expression and phenotype. In this study we present an analysis of epigenome changes in rice hybrids that were obtained by crossing rice cultivars, most of them of indica type and Thai origin. Comparing amplified fragment length polymorphism (AFLP) fingerprints of twenty-four cultivars, we calculated Nei’s indexes for measuring genetic relationships. Epigenetic changes in their hybrids were established using methylation-sensitive AFLP fingerprinting and transposon display of the rice transposable elements (TEs) Stowaway Os-1 and Mashu, leading to the question whether the relationship between parental genomes is a predictor of epigenome changes, TE reactivation and changes in TE methylation. Our study now reveals that the genetic relationship between the parents and DNA methylation changes in their hybrids is not significantly correlated. Moreover, genetic distance correlates only weakly with Mashu reactivation, whereas it does not correlate with Stowaway Os-1 reactivation. Our observations also suggest that epigenome changes in the hybrids are localized events affecting specific chromosomal regions and transposons rather than affecting the genomic methylation landscape as a whole. The weak correlation between genetic distance and Mashu methylation and reactivation points at only limited influence of genetic background on the epigenetic status of the transposon. Our study further demonstrates that hybridizations between and among specific japonica and indica cultivars induce both genomic DNA methylation and reactivation/methylation change in the Stowaway Os-1 and Mashu transposons. The observed epigenetic changes seem to affect the transposons in a clear manner, partly driven by stochastic processes, which may account for a broader phenotypic plasticity of the hybrids. A better understanding of the epigenome changes leading to such transposon activation can lead to the development of novel tools for more variability in future rice breeding. 相似文献