Genetic diversity in the male-specific <Emphasis Type="Italic">SRY</Emphasis> gene of <Emphasis Type="Italic">Lepus yarkandensis</Emphasis>

Lepus yarkandensis, an endemic hare species in the Tarim Basin of China, has been suffering from habitat fragmentation due to desert expansion. To evaluate the effect of habitat fragmentation on its genetic diversity, the genetic diversity based on male-specific SRY gene marker is examined. A relatively low level of SRY genetic diversity is found compared to previous studies with mtDNA data, possibly due to the low SRY mutation rate and positive selection. Furthermore, one haplotype exists in eight populations along the Tarim River but not in many other relatively isolated populations, suggesting that habitat fragmentation may affect population divergence. Despite this, our pairwise Fst analysis shows no significant differentiation among populations, and this may be mainly caused by positive selection on the SRY gene in that 88 percent of individuals share the same haplotype. Finally, the phylogenetic analysis shows deep differentiation between L. yarkandensis and other two hare species (L. capensis and L. europaeus).     

Studies of new EST-SSRs derived from Gossypium barbadense

Existing cotton EST-SSR markers are mostly derived from Gossypium arboreum and Gossypium hir-sutum, but EST-SSR markers from Gossypium barbadense are scarce. One hundred and nineteen EST-SSRs were developed based on 98 unique ESTs from a cDNA library constructed in our laboratory using developing fibers from G. barbadense cv. Pima3-79. Among the SSRs, trinucleotide AAG appeared at a high frequency of 11.76%. 36 accessions (consisting of 13 diploids of the A genome, 11 diploids of the D genome and 12 allotetraploids of the AD genome) were employed to test new EST-SSRs. 76 EST-SSRs were successfully amplified, and 313 polymorphic fragments were yielded, with an average of 4.11 fragments per primer pair. The PIC ranged from 0.17 to 0.95 with an average of 0.53. Based on Jaccard’s genetic similarity coefficient, these 36 accessions were clustered into three groups. 21 EST-SSRs exhibited polymorphisms in BC1 population ((Emian22 × Pima3-79) × Emian22), 24 polymor- phic loci were generated, while 22 of the 24 polymorphic loci were integrated with our interspecific BC1 backbone genetic linkage map, and anchored in 12 chromosomes. This study effectively proved that EST-SSRs from G. barbadense are valuable for genetic diversity analysis and genetic mapping.     

High genetic diversity of Tibetan Mastiffs revealed by mtDNA sequences

Many studies have been reported the origin and evolution of domesticated animals, particularly dogs, however, few have system-atically examined the Tibetan Mastiff (TM), a dog that lives primarily in the Qing-Tibet Plateau. Here, we study the origin and evolution of TM based on the population comparison of mtDNA D-loop sequences from TM and other dogs across the world. Intriguingly, non-simultaneous arrivals of Tibetan Mastiffs ancestors to Tibet occurred, which may result from continuous Tibetans’ settlement on Qing-Tibet Plateau supported by archaeological and genetic evidence. High genetic and haplotype diversity and robust haplotypes sharing with other dogs unique to East Asia are observed in Tibetan Mastiff, supporting that it is a very archaic breed derived probably from East Asia.     

利用微卫星标记分析贵州水牛的遗传多样性

通过对贵州水牛的遗传多样性进行分析,为正确评估贵州水牛的资源价值、制定合理可行的保种方案提供理论依据.利用11对多态性较高的微卫星引物对贵州7个水牛群体的有效等位基因数、基因杂合度、多态信息含量和遗传距离进行分析.贵州7个水牛群体的平均有效等位基因数、平均杂合度和平均多态信息含量分别为4.0823～4.8951、0.7450～0.7922和0.7021～0.7605;遗传距离最远的黔南水牛和毕节水牛为0.3084;由UPGMA聚类法将贵州7个水牛群体聚为4类.贵州水牛遗传多样性丰富,具有较好的遗传潜力;对贵州水牛的划分比传统分类法更能反映实际的生态地理环境及其历史形成状况.     

The genetic diversity of central and peripheral populations of ratlike hamster (<Emphasis Type="Italic">Cricetulus triton</Emphasis>)

The impact of habitat fragmentation and isolation on the genetic diversity of populations has attracted much attention in studies of meta-population and conservation biology. In this work, using the randomly amplified polymorphic DNA (RAPD) technique, we studied the genetic diversity of central, peripheral and peninsular populations of ratlike hamster, which were collected in five locations of the North China Plain and its surrounding areas, in 1999. The study revealed that, i) the genetic diversity of central population of Raoyang County>the sub-central populations of Gu’an County and Taikang County > the peripheral population of Shunyi District>the peninsular population of Mentougou District; ii) the genetic diversities of the five populations were positively correlated to the nearest distances to the peripheral line of population distribution; iii) there were significant differences of gene frequencies of some RAPD fragments among the five populations. More RAPD fragments disappeared in peripheral populations than in central or sub-central populations. The frequencies of two RAPD fragments were correlated to the latitude. This study clearly indicated that the variation of the genetic diversities of the five populations was caused by edge effect and fragmentation through the enhanced inbreeding and genetic drift, and thus supported the view that habitat fragmentation and related edge effect reduce the population genetic diversity.     

Assessment of genetic diversity in the forest musk deer （Moschus berezovskii） using microsatellite and AFLP markers

Microsatellite genotyping and amplified fragment length polymorphism (AFLP) techniques are often utilized in studies of conservation genetics of endangered animals. To select a more effective marker system for conserving the endangered forest musk deer, we used microsatellite and AFLP markers to estimate levels of genetic diversity of two populations, the pure mother Jinfengshan (JFS) group and the offspring Baisha (BS) group with introduction of new blood. It was expected that JFS would pos- sess significa...     

Transpositional behaviour of the Ds element in the Ac/Ds system in rice

Insertional mutagenesis based on maize Activator/Dissociator (Ac/Ds) transposons is becoming a ma- jor approach used to produce a saturated mutant collection in rice. In this research, Ds-T-DNA trans- formed homozygotes were crossed with Ac-T-DNA transformed homozygotes in order to establish an Ac/Ds transposon system in rice. The successive investigation of Ds transposition from F1 to F5 gen- erations indicated that the frequencies of germinal transposition increased over successive genera- tions and reached 54.2% in F3 generation. The Ds transposition pattern revealed that a Ds transposition induced an approximately 170-bp deletion of T-DNA sequence and another Ds transposition carried a 272-bp T-DNA sequence. Using thermal asymmetric interlaced PCR (TAIL-PCR), some flanking se- quences of the Ds element were amplified. Analyses of 17 Ds-flanking sequences showed that five Ds were inserted into gene regions. The Ds could transpose not only to the linked sites but also to the unlinked sites. The frequency of inter-chromosomal transposition of Ds was 33.3%.     

Asymmetric epoxidation of <Emphasis Type="Italic">α</Emphasis>,<Emphasis Type="Italic">β</Emphasis>-unsaturated ketones using <Emphasis Type="Italic">α</Emphasis>,<Emphasis Type="Italic">α</Emphasis>-diarylprolinols as catalysts

Asymmetric epoxidation of α,β-unsaturated ketones has been extensively studied and several important procedures have been developed in the last decade. This review addresses the most significant advances in asymmetric epoxidation of α,β-unsaturated ketones using proline-derived α,α-diarylprolinols as catalysts. Special attention has been paid to the enantioselective epoxidation of chalcones, α,β-unsaturated trifluoromethyl, trichloromethyl ketones and β,γ-unsaturated α-keto esters based on the reseach of our group.     

The R- and AR-indices： Complementing the h-index

Based on the foundation laid by the h-index we introduce and study the R- and AR-indices. These new indices eliminate some of the disadvantages of the h-index, especially when they are used in combina-tion with the h-index. The R-index measures the h-core’s citation intensity, while AR goes one step further and takes the age of publications into account. This allows for an index that can actually in-crease and decrease over time. We propose the pair (h, AR) as a meaningful indicator for research evaluation. We further prove a relation characterizing the h-index in the power law model.     

Osmotically stress-regulated the expression of glutathione peroxidase 3 in Arabidopsis

Gene expression of glutathione peroxidase 3 (ATGPX3) in response to osmotic stress was analyzed in Arabidopsis using ATGPX3 promoter-glucuronidase (GUS) transgenic plants. High levels of GUS ex- pression were detected under osmotic stress in ATGPX3 promoter-GUS transgenic plants. Compared with the wild type, the growth and development of ATGPX3 mutants (atgpx3-1) were more sensitive to mannitol. In addition, the expression of RD29A, ABI1, ABI2 and RbohD in atgpx3-1 was induced by ABA stress. These results suggest that ATGPX3 might be involved in the signal transduction of osmotic stress.     

Genetic diversity of Tricholoma matsutake in Yunnan Province

To investigate the genetic diversity of Tricholoma matsutake,we studied ITS and IGS1 sequences and PCR polymorphism of a retrotransposon in 56 fruit bodies collected from 13 counties of 9 regions in Yunnan Province. We found one and three haplotypes based on ITS and IGS1 sequences,respectively. Moreover,there was no significant difference in PCR polymorphism of the retrotransposon among different populations. Compared with Jilin Province(China) and Japanese populations,although Yun-nan was highly homogenous to Japanese populations,low genetic diversity of T. matsutake in Yunnan did not support the view that this species originated from Yunnan.     

Genetic analysis and gene fine mapping of a rolling leaf mutant (<Emphasis Type="Italic">rl</Emphasis><Subscript><Emphasis Type="Italic">11(t)</Emphasis></Subscript>) in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

The exploration of new genes controlling rice leaf shape is an important foundation for rice functional genomics and plant archi-tecture improvement. In the present study, we identified a rolling leaf mutant from indica variety Yuefeng B, named rl_11(t), which exhibited reduced plant height, rolling and narrow leaves. Leaves in rl_11(t) mutant showed abnormal number and morphology of veins compared with those in wild type plants. In addition, rl_11(t) mutant was less sensitive to the inhibitory effect of auxin than the wild type. Genetic analysis suggested that the mutant was controlled by a single recessive gene. Gene Rl_11(t) was initially mapped between SSR markers RM6089 and RM124 on chromosome 4. Thirty-two new STS markers around the Rl_11(t) region were developed for fine mapping. A physical map encompassing the Rl_11(t) locus was constructed and the target gene was finally delimited to a 31.6 kb window between STS4-25 and STS4-26 on BAC AL606645. This provides useful information for cloning of Rl_11(t) gene.     

Genetic diversity in the Yangtze finless porpoise by RAPD analysis

To estimate the genetic diversity in the Yangtze finless porpoise ( Neophocaena phocaenoides asiaeorientalis), the randomly amplified polymorphie DNA technique was applied to examine ten animals captured from the Yangtze River. Out of 20 arbitrary primers used in the experiment, seventeen produced clearly reproducible bands. Calculated by Nei‘s formula d = 1-NAB/NT, the genetic distances ranged from O. 0986 to O. 5634. Compared with other cetacean populations, this genetic distance is quite low.Such a low genetic diversity suggests that this population may be suffering from reduced genetic variation,and be very fragile. More studies are needed for understanding the basis for this apparent low genetic diversity and to help protect this endangered, unique population.     

Comparative and statistical analysis of nAChR sequences: An <Emphasis Type=Italic>ab initio</Emphasis> approach to the origin of molecular discrimination

Compared with traditional structure-based approaches for the identification of species-specific ligands, the ab initio approach, based on large-scale protein sequences from different species, has been used to locate specific sites that may be important to the molecular selectivity of species. Statistically significant differences in the distribution of residues in different species and differences in the physicochemical properties of residue-specific sites may largely account for species selectivity. The nicotinic acetylcholine receptor (nAChR), an important neuro-receptor with significantly different ligand selectivity in different species, was used to test our method. Because of the lack of nAChR structural information, the mechanism of ligand discrimination is unclear which hinders attempts at novel molecular design. In this study, the specific site residues 186 and 189 in the principal subunits and residues 34, 55, 56, 57, 106 and 112 in complementary subunits of nAChR were identified by applying our method with stringent statistical cutoffs. These sites were predicted to contribute to ligand selectivity and this result coincides well with the known experimental data.     

Analysis of genetic variation within and among <Emphasis Type="Italic">Ulva pertusa</Emphasis> (Ulvaceae,Chlorophyta) populations using ISSR markers

Ulva pertusa is a native species to Asia along the western coast of Pacific Ocean,with new occurrence records in the eastern coast of Pacific,the northwest coast of Atlantic and the Mediterranean Sea.However,little is known about its population genetic structure.In this study,twelve U.pertusa populations from 3 coastal areas of China:Qingdao,Yantai and Dalian,were applied to ISSR analysis.The selected 4 ISSR primers amplified 120 polymorphic bands totally.Nei's gene diversity (H) ranged from 0.0729 to 0.149...