The worldwide distribution and extensive genetic diversity of the whitefly,Bemisia tabaci,has long been recognized.However,the levels of separation within B.tabaci and the nomenclature of the various genetic groups ha...The worldwide distribution and extensive genetic diversity of the whitefly,Bemisia tabaci,has long been recognized.However,the levels of separation within B.tabaci and the nomenclature of the various genetic groups have been a subject of debate.Recent phylogenetic analyses indicate that B.tabaci is a complex composed of 28 morphologically indistinguishable species.In this article,we first review the debate and difficulties associated with B.tabaci＇s taxonomy and systematics,and argue for the need to apply the biological species concept in order to elucidate B.tabaci＇s systematics.We summarize the accumulated genetic and behavioural data on reproductive incompatibilities evident amongst phylogenetic mtCOI groups of B.tabaci.Crossing studies have been conducted with 14 of the 28 putative species covering 54 reciprocal inter-species pairs,and observations on mating behaviour have been conducted for seven species pairs.Data from both crossing trials and behavioural observations indicate a consistent pattern of reproductive isolation among the putative species.We then discuss the technical and conceptual complexities associated with crossing experiments and behavioural observations designed to reveal reproductive incompatibility.Finally,we elaborate on a strategy for further clarifying the pattern of reproductive isolation between B.tabaci groups and propose future research directions on the systematics of this complex.展开更多
An antibacterial protein was isolated from the cultured mycelia of Cordyceps sinensis, and was designated as Cordyceps sinensis Antibacterial Protein （CSAP）. CSAP was single-chained, with an apparent molecular mass ...An antibacterial protein was isolated from the cultured mycelia of Cordyceps sinensis, and was designated as Cordyceps sinensis Antibacterial Protein （CSAP）. CSAP was single-chained, with an apparent molecular mass of 35 × 10^3 revealed by SDS-PAGE and a novel hydrophobic N-terminal sequence N-ALATQHGAP. The antimicrobial assays showed CSAP could inbibit the growth of Gram-positive and Gram-negative bacteria but no significant inhibition against fungi or yeasts. Further more, the antibacterial activity of CSAP was not bactericidal but bacteriostatic. It was the first time that an antibacterial protein was described in the Cordyceps species, which might involve in the chemical defense mechanism of the hosts.展开更多
Geographic isolation is a key factor in shaping the genetic structure of many fish species.Two sympatric species,Culter alburnus and C.mongolicus,are economically important fish that are widely distributed in China an...Geographic isolation is a key factor in shaping the genetic structure of many fish species.Two sympatric species,Culter alburnus and C.mongolicus,are economically important fish that are widely distributed in China and have been recently used as new aquaculture species.We used the mitochondrial DNA control region(CR)as a marker to investigate the genetic structure of the two species.Phylogenetic analysis revealed two major lineages(Lineages I and II)that were highly consistent with geographical patterns for C.alburnus and C.mongolicus.Based on genetic distance,the Zhujiang(Pearl)River Basin(ZRB)populations potentially represented a cryptic subspecies,which might be differentiated as the result of strict geographic isolation,an earlier diverged event,or peripheral areas.Genetic diversity analysis suggested that the Changjiang(Yangtze)River Basin(CRB)populations are located at,or near the core region of their origination,not only due to the larger population size at the CRB,but also their habitat diversity and suitability for its survival,and the genetic diversity dif ferences among basin populations were significant for the two species.Moreover,demographic analysis indicated that the two Culter species and most populations had undergone a period of population expansion during warm interglacial periods.However,the C.alburnus population of Huaihe River Basin(Weishan Lake)exhibited different patterns during the interglacial period,which may due to the latest diverged time of HRB and Weishan Lake located at the permafrost.Notably,the ZRB(in Songtao Reservoir)C.mongolicus population showed no genetic diversity and had a unique haplotype,which could be treated as a special gene pool for species conservation.In summary,geographic isolation is most likely responsible for the two Culter species distribution patterns.展开更多
基金funded by the National Basic Research Program of China(2009CB119203)the National NaturalScience Foundation of China(30730061)the ChinaAgriculture Research System(CARS-25-B-08)
文摘The worldwide distribution and extensive genetic diversity of the whitefly,Bemisia tabaci,has long been recognized.However,the levels of separation within B.tabaci and the nomenclature of the various genetic groups have been a subject of debate.Recent phylogenetic analyses indicate that B.tabaci is a complex composed of 28 morphologically indistinguishable species.In this article,we first review the debate and difficulties associated with B.tabaci＇s taxonomy and systematics,and argue for the need to apply the biological species concept in order to elucidate B.tabaci＇s systematics.We summarize the accumulated genetic and behavioural data on reproductive incompatibilities evident amongst phylogenetic mtCOI groups of B.tabaci.Crossing studies have been conducted with 14 of the 28 putative species covering 54 reciprocal inter-species pairs,and observations on mating behaviour have been conducted for seven species pairs.Data from both crossing trials and behavioural observations indicate a consistent pattern of reproductive isolation among the putative species.We then discuss the technical and conceptual complexities associated with crossing experiments and behavioural observations designed to reveal reproductive incompatibility.Finally,we elaborate on a strategy for further clarifying the pattern of reproductive isolation between B.tabaci groups and propose future research directions on the systematics of this complex.
基金Supported by the National Natural Science Foundation of China(39770200) the Natural Science Foundation of Hubei Province (2004ABA228)
文摘An antibacterial protein was isolated from the cultured mycelia of Cordyceps sinensis, and was designated as Cordyceps sinensis Antibacterial Protein （CSAP）. CSAP was single-chained, with an apparent molecular mass of 35 × 10^3 revealed by SDS-PAGE and a novel hydrophobic N-terminal sequence N-ALATQHGAP. The antimicrobial assays showed CSAP could inbibit the growth of Gram-positive and Gram-negative bacteria but no significant inhibition against fungi or yeasts. Further more, the antibacterial activity of CSAP was not bactericidal but bacteriostatic. It was the first time that an antibacterial protein was described in the Cordyceps species, which might involve in the chemical defense mechanism of the hosts.
基金Supported by the National Key Technology Research and Development Program(No.2015BAD25B01)the Earmarked Fund for China Agriculture Research system(No.CARS-45)
文摘Geographic isolation is a key factor in shaping the genetic structure of many fish species.Two sympatric species,Culter alburnus and C.mongolicus,are economically important fish that are widely distributed in China and have been recently used as new aquaculture species.We used the mitochondrial DNA control region(CR)as a marker to investigate the genetic structure of the two species.Phylogenetic analysis revealed two major lineages(Lineages I and II)that were highly consistent with geographical patterns for C.alburnus and C.mongolicus.Based on genetic distance,the Zhujiang(Pearl)River Basin(ZRB)populations potentially represented a cryptic subspecies,which might be differentiated as the result of strict geographic isolation,an earlier diverged event,or peripheral areas.Genetic diversity analysis suggested that the Changjiang(Yangtze)River Basin(CRB)populations are located at,or near the core region of their origination,not only due to the larger population size at the CRB,but also their habitat diversity and suitability for its survival,and the genetic diversity dif ferences among basin populations were significant for the two species.Moreover,demographic analysis indicated that the two Culter species and most populations had undergone a period of population expansion during warm interglacial periods.However,the C.alburnus population of Huaihe River Basin(Weishan Lake)exhibited different patterns during the interglacial period,which may due to the latest diverged time of HRB and Weishan Lake located at the permafrost.Notably,the ZRB(in Songtao Reservoir)C.mongolicus population showed no genetic diversity and had a unique haplotype,which could be treated as a special gene pool for species conservation.In summary,geographic isolation is most likely responsible for the two Culter species distribution patterns.
