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101.
We describe a new species from the family Salamandridae from northeastern Hunan Province of China based on morphological and molecular genetic evidences.The new species,Tylototriton liuyangensis,is a member of the T.asperrimus group,and shares a number of similarities with T.wenxianensis and T.broadoridgus.The dorsal surface of the new Tylototriton species is completely black,with nodule-like warts distributed evenly along the lateral margin of dorsal body,and there is no transverse striae between the warts.There are several diagnostic characters of the new species that differ from those of T.wenxianensis and T.broadoridgus as follows:(1)the interorbital space(IOS)is comparatively wide;(2)there is a bony ridge present on the dorsal head surface,running along the upper eyelids;(3)the space between axilla and groin(AGS)is comparatively large,with the mean male AGS approximately equal to 50%of the snout-vent length(SVL)and the mean female AGS being 53%of SVL;and(4)there is a small genital armature on the anterior angle of labial folds present inside the anal fissure of adult males during the breeding season.The result from the molecular phylogenetic analysis of the genus Tylototriton(including the type specimen of the new species)based on the complete DNA sequence of the mitochondrial ND2 gene(1035 bp)indicated that the new species was similar to T.wenxianensis,T.dabienicus,and T.broadoridgus,but formed an independent clade.This result was consistent with the morphological analysis above,supporting that the Liuyang Population represented a distinct species.  相似文献   
102.
Co-evolutionary theory assumes co-adapted characteristics are a positive response to counter those of another species,whereby co-evolved species reach an evolutionarily stable interaction through bilateral adaptation.However,evidence from the fig-fig wasp mutualistic system implies very different co-evolutionary selection mechanisms,due to the inherent conflict among interacted partners.Fig plants appear to have discriminatively enforced fig wasps to evolve"adaptation characteristics"that provide greater benefit to the fig,and fig wasps appear to have diversified their evolutionary strategies in response to discriminative enforcement by figs and competition among different fig wasp species.In what appears to be an asymmetric interaction,the prosperity of cooperative pollinating wasps should inevitably lead to population increases of parasitic individuals,thus resulting in localized extinctions of pollinating wasps.In response,the sanctioning of parasitic wasps by the fig should lead to a reduction in the parasitic wasp population.The meta-populations created by such asymmetric interactions may result in each population of coevolved species chaotically oscillated,temporally or evolutionarily.  相似文献   
103.
Teeth are one of the most important materials for anthropological studies because they are likely to be preserved in ancient remains.While the frequencies of dental characteristics can provide clues to the phylogeny of populations,genetic studies at the individual level can further reveal the biological mechanisms and evolutionary context of dental characteristics.In this study,by analyzing 38 dental characteristics of 242 Xinjiang Uyghur individuals,we found that(i)the dental characteristics of the Uyghurs showed evidence of admixture between European and East Asian populations.The admixture proportions were in line with those previously reported in population genetic studies;(ii)the Xinjiang Uyghur dental characteristics formed three clusters in pairwise correlation analysis.One of the main clusters consisted of characteristics including incisor shoveling,double shoveling and mesial ridge;and(iii)all the characteristics in this cluster were significantly correlated with the genetic variant EDARV370A.The extracted composite phenotypic factor was also significantly associated with EDARV370A,which explained 18%of the total phenotypic variance.This indicated a pleiotropic effect,i.e.,the same genetic factor affects a number of dental characteristics at the same time.Our results confirmed that EDARV370A,a genetic variant that first originated in East Asia about 30000 years ago,played an important role in incisor shoveling in East Asia.This finding suggested that incisor shoveling in modern humans in East Asia is likely to have appeared after the late Pleistocene.  相似文献   
104.
105.
Research of blastocyte-like structure in chicken   总被引:1,自引:0,他引:1  
Embryonic stem (ES) cells known to be one of the most brilliant stars enlightening the biology science are a major tool to investigate embryonic development and differentiation, functional genomics and applied in medicine territory for cellular therapy. Even though some scientists have already established cultural sys-tems for selection and maintenance of putative avian ES cells, the study on them still drops behind the mammalian and proceeds slowly. The avian ES cells can be used to produce…  相似文献   
106.
Most proterminal regions of human chromosomes are GC-rich and gene-rich. Chromosome 3p is an exception. Its proterminal region is GC-poor, and likely to lose heterozy-gosity, thus causing a number of fatal diseases. Except one gap left in the telomeric position, the proterminal region of human chromosome 3p has been completely sequenced. The detailed sequence analysis showed: (i) the GC content of this region was 38.5%, being the lowest among all the human proterminal regions; (ii) this region contained 20 known genes and 22 predicted genes, with an average gene size of 97.5 kb. The previously mapped gene Cntn3 was not found in this region, but instead located in the 74 Mb position of human chromosome 3p; (iii) the interspersed repeats of this region were more active than the average level of the whole human genome, especially (TA)n, the content of which was twice the genome average; (iv) this region had a conserved synteny extending from 104.1 Mb to 112.4 Mb on the mouse chromosome 6, which was 8% larger in size, not in accordance with the whole genome comparison, probably because the 3pter-p26 region was more likely to lose neocleitides and its mouse synteny had more active interspersed repeats.  相似文献   
107.
Th1-type cytokines produced by the stimulation of Th1-type epitopes derived from definedschistosome-associated antigens are correlated with the development of resistance to the parasite infection.Schistosoma mansoni 28 kDa glutathione-S-transferase(Sm28GST),a major detoxification enzyme,hasbeen recognized as a vaccine candidate and a phase Ⅱ clinical trial has been carried out.Sheep immunizedwith recombinant Schistosoma japonicum 28GST(Sj28GST)have shown immune protection against theparasite infection.In the present study,six candidate peptides(P1,P2,P3,P4,P7 and P8)from Sj28GSTwere predicted,using software,to be T cell epitopes,and peptides P5 and P6 were designed by extendingfive amino acids at the N-terminal and C-terminal of P1,respectively.The peptide 190-211 aa in Sj28GSTcorresponding to the Th1-type epitope(190-211 aa)identified from Sm28GST was selected and named P9.The nine candidate peptides were synthesized or produced as the fusion protein with thioredoxin in thepET32c(+)/BL21(DE3)system.Their capacity to induce a Th1-type response in vitro was measured usinglymphocyte proliferation,cytokine detection experiments and flow cytometry.The results showed that P6(73-86 aa)generated the strongest stimulation effect on T cells among the nine candidate peptides,and drovethe highest level of IFN-γ and IL-2.Therefore,P6 is a functional Th1-type T cell epitope that is differentfrom that in Sm28GST,and will be useful for the development of effective vaccines which can triggeracquired immunity against S.japonicum.Moreover,our strategy of identifying the Th1-type epitope by acombination of software prediction and experimental confirmation provides a convenient and cost-savingalternative approach to previous methods.  相似文献   
108.
Two New Saponins from Lysimachia capillipes Hemsl.   总被引:1,自引:0,他引:1  
To investigate the saponins from whole plants of Lysimachia capillipes Hemsl., two new saponins, named capilliposide E (1) and capilliposide F (2), were isolated. The structures of the new sa ponins were elucidated as 3 β, 22α-dihydroxy- 16α-acetat-28→ 13 -lactone-oleanane-3 -O- [β-D-glucopyranosyl(1→2)-α-L-arabinpyranoyl]-22-O-β-D-glucopyranoside (1) and 3 β, 22α-dihydroxy- 16α-acetat-28→ 13-1actone-oleanane-3-O- { [β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-(1→4)]-α-L-arabinpyranoyl }-22-O-βD-glucopyranoside (2). The structures of these compounds were determined by 1D- and 2D-NMR, MS techniques, and chemical methods.  相似文献   
109.
One oil-degrading bacterial strain 1217 isolated from oil contaminated soil could degrade crude oil. It was identified and designated as Pseudomonas aeruginosa by morphology, physiology, biochemical and 16S rDNA sequence analyses. The strain grew well at 5-65 ℃ with the initial pH of 2-10 and NaCl concentrations of 0%-9%. It grew well in the medium containing different organic substrates as sole carbon sources, such as n-dodecane, n-octadecane, benzene, toluene, xylene and naphthaline. The degrading rates for hydrocarbons were 21.57% and 15.15% when it was cultured in minimal medium containing crude oil and different chain alkanes at 30 ℃ and 10 ℃ for 7 days. The bacterium produced biosurfactants with the surface tension reduction from 72.20 mN/m to 35.14 mN/m. The oil degrading related genes such as alkane monooxygenase, toluene dioxygenase, biphenyl dioxygenase, ring hydroxylating dioxygenase and oxidoreductase genes were detected in Pseudomonas aeruginosa 1217. The alkane monooxygenase and ring hydroxylating dioxygenase genes were further cloned and analyzed. The sequence similarities of the two genes with those of Pseudomonas aeruginosa PAO1 were 99.91% and 99.22% respectively. The isolated strain exhibits great potential for the bioremediation of the hydrocarbons contaminated environments.  相似文献   
110.
Mac-1 (macrophage differentiation antigen asso-ciated with complement three receptor function), alsonamed CD11b/CD18, an adhesion molecule belongingresting leukocytes and at the surface of activated leu-kocytes (macrophages and neutrophils). Mac-1 playsan important role in the migration, chemotaxis and 2 Methodsphagocytosis of leukocytes[1]. Although there have 2.1 Observation of PMA-stimulated Mac-1 traffick-been several reports on the role of Mac-1 in neutrophil ingadh…  相似文献   
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