[Objective] The study aimed to further understand the genetic quality of Xiphophorus helleri RR-B strain and estimate the feasibility of microsatellite markers in genetic monitoring of aquatic laboratory animals.[Meth...[Objective] The study aimed to further understand the genetic quality of Xiphophorus helleri RR-B strain and estimate the feasibility of microsatellite markers in genetic monitoring of aquatic laboratory animals.[Method] Eighteen microsatellite loci which had polymorphism in wild X. helleri were used for genetic quality analysis of RR-B strain (red eyes and red body) by PCR. [Result] All these 18 microsatellite loci displayed single allelic gene band in 30 individuals of X. helleri RR-B strain and the average homozygote rate reached 100%. [Conclusion] These loci could be used as markers in genetic monitoring of X. helleri RR-B strain, which had obtained fairly high genetic homozygosity by inbreeding for more than 20 generations. This study provided basic data for establishing the molecular genetic monitoring standard of aquatic laboratory animals.展开更多
In contrast to mammals and birds,fish display an amazing diversity of genetic sex determination systems,with frequent changes during evolution possibly associated with the emergence of new sex chromosomes and sex-dete...In contrast to mammals and birds,fish display an amazing diversity of genetic sex determination systems,with frequent changes during evolution possibly associated with the emergence of new sex chromosomes and sex-determining genes.To better understand the molecular and evolutionary mechanisms driving this diversity,several fish models are studied in parallel.Besides the medaka(Oryzias latipes Temminck and Schlegel,1846)for which the master sex-determination gene has been identified,one of the most advanced models for studying sex determination is the Southern platyfish(Xiphophorus maculatus,Günther 1966).Xiphophorus maculatus belongs to the Poeciliids,a family of live-bearing freshwater fish,including platyfish,swordtails and guppies that perfectly illustrates the diversity of genetic sex-determination mechanisms observed in teleosts.For X.maculatus,bacterial artificial chro-mosome contigs covering the sex-determination region of the X and Y sex chromosomes have been constructed.Initial molecular analysis demonstrated that the sex-determination region is very unstable and frequently undergoes duplications,deletions,inversions and other rearrangements.Eleven gene candidates linked to the master sex-determining gene have been identified,some of them corresponding to pseudogenes.All putative genes are present on both the X and the Y chromosomes,suggesting a poor degree of differentiation and a young evolutionary age for platyfish sex chromosomes.When compared with other fish and tetrapod genomes,syntenies were detected only with autosomes.This observation supports an independent origin of sex chromosomes,not only in different vertebrate lineages but also between different fish species.展开更多
A consensus sequence, encoding a putative DNA polymerase type B derived from a Polinton transposon, was assembled from the sex determination region of Xiphophorus maculatus. This predicted protein, which is 1,158 aa i...A consensus sequence, encoding a putative DNA polymerase type B derived from a Polinton transposon, was assembled from the sex determination region of Xiphophorus maculatus. This predicted protein, which is 1,158 aa in length, contains a DNAA_pol_B_2 domain and a DTDS motif. The DNA polymerase type B gene has about 10 copies in the haploid X. maculatus genome with one Y-specific copy. Interestingly, it has specific copies on the W chromosome in the X. maculatus Usumacinta strain （sex determination with female het- erogamety）, which represent new markers for this type of sex chromosome in platyfish. This marker with W- and Y-specific copies suggests relationship between different types of gonosomes and allows comparing male and female heterogameties in the platyfish. Further molecular analysis of the DNA polymerase type B gene in X. maculatus will shed new light on the evolution of sex chromosomes in platyfish.展开更多
Objective:To determine toxicity and safety margins of trichlorofon in different species as trichlorofon toxicity has a large variation in the susceptibility of different species.Methods:In this research,four viviparou...Objective:To determine toxicity and safety margins of trichlorofon in different species as trichlorofon toxicity has a large variation in the susceptibility of different species.Methods:In this research,four viviparous aquarium fish were exposed to trichlorofon for 96 h.LC_(50)of 24 h,48 h,72 h and 96 h were attained by probit analysis software SPSS Version 16.Fish samples were exposed to different concentrations of trichlorofon(5,10,20 and 40 mg/L)for 96 h and mortality were recorded,separately.Results:The 96 h LC_(50)of Poecilia latipinna,Poecilia reticulata a,Gambusia holbrooki and Xiphophorus helleri were 9.80,9.80,9.95 and 7.99 mg/L,respectively.Conclusions:According to the results of this research,LC_(50)values indicated Xiphophorus helleri was the most resistant and Gambusia holbrooki,with a few differences,was the most sensitive species compared with the fishes examined.展开更多
Although the majority of studies on mate choice focus on female mate choice, there is growing recognition of the role of male mate choice too. Male mate choice is tightly linked to 2 other phenomena： female competiti...Although the majority of studies on mate choice focus on female mate choice, there is growing recognition of the role of male mate choice too. Male mate choice is tightly linked to 2 other phenomena： female competition for males and ornamentation in females. In the current article, I review the existing literature on this in a group of fishes, Poeciliidae. In this group, male mate choice appears to be based on differences in female quality, especially female size, which is a proxy for fecundity. Some males also have to choose between heterospecific and conspecific females in the unusual mating system of the Amazon molly. In this case, they typically show a preference for conspecific females. Whereas male mate choice is relatively well documented for this family, female ornamentation and female competition are not.展开更多
基金Supported by Science and Technology Planning Project of Guangdong Province(2005B20301014)Program of National Science and Technology Platform System of China(2005DKA21103)~~
文摘[Objective] The study aimed to further understand the genetic quality of Xiphophorus helleri RR-B strain and estimate the feasibility of microsatellite markers in genetic monitoring of aquatic laboratory animals.[Method] Eighteen microsatellite loci which had polymorphism in wild X. helleri were used for genetic quality analysis of RR-B strain (red eyes and red body) by PCR. [Result] All these 18 microsatellite loci displayed single allelic gene band in 30 individuals of X. helleri RR-B strain and the average homozygote rate reached 100%. [Conclusion] These loci could be used as markers in genetic monitoring of X. helleri RR-B strain, which had obtained fairly high genetic homozygosity by inbreeding for more than 20 generations. This study provided basic data for establishing the molecular genetic monitoring standard of aquatic laboratory animals.
文摘In contrast to mammals and birds,fish display an amazing diversity of genetic sex determination systems,with frequent changes during evolution possibly associated with the emergence of new sex chromosomes and sex-determining genes.To better understand the molecular and evolutionary mechanisms driving this diversity,several fish models are studied in parallel.Besides the medaka(Oryzias latipes Temminck and Schlegel,1846)for which the master sex-determination gene has been identified,one of the most advanced models for studying sex determination is the Southern platyfish(Xiphophorus maculatus,Günther 1966).Xiphophorus maculatus belongs to the Poeciliids,a family of live-bearing freshwater fish,including platyfish,swordtails and guppies that perfectly illustrates the diversity of genetic sex-determination mechanisms observed in teleosts.For X.maculatus,bacterial artificial chro-mosome contigs covering the sex-determination region of the X and Y sex chromosomes have been constructed.Initial molecular analysis demonstrated that the sex-determination region is very unstable and frequently undergoes duplications,deletions,inversions and other rearrangements.Eleven gene candidates linked to the master sex-determining gene have been identified,some of them corresponding to pseudogenes.All putative genes are present on both the X and the Y chromosomes,suggesting a poor degree of differentiation and a young evolutionary age for platyfish sex chromosomes.When compared with other fish and tetrapod genomes,syntenies were detected only with autosomes.This observation supports an independent origin of sex chromosomes,not only in different vertebrate lineages but also between different fish species.
基金supported by the grants from the Biofuture Programme of the German Federal Ministry for Education and Research (BMBF,to JNV),the French Research Agency (ANR to JNV)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,the Ministry of Education of China (to QZ)
文摘A consensus sequence, encoding a putative DNA polymerase type B derived from a Polinton transposon, was assembled from the sex determination region of Xiphophorus maculatus. This predicted protein, which is 1,158 aa in length, contains a DNAA_pol_B_2 domain and a DTDS motif. The DNA polymerase type B gene has about 10 copies in the haploid X. maculatus genome with one Y-specific copy. Interestingly, it has specific copies on the W chromosome in the X. maculatus Usumacinta strain （sex determination with female het- erogamety）, which represent new markers for this type of sex chromosome in platyfish. This marker with W- and Y-specific copies suggests relationship between different types of gonosomes and allows comparing male and female heterogameties in the platyfish. Further molecular analysis of the DNA polymerase type B gene in X. maculatus will shed new light on the evolution of sex chromosomes in platyfish.
基金Supported by the Gorgan University of Agriculture Science and Natural Resource(Grant No.6177515-5).
文摘Objective:To determine toxicity and safety margins of trichlorofon in different species as trichlorofon toxicity has a large variation in the susceptibility of different species.Methods:In this research,four viviparous aquarium fish were exposed to trichlorofon for 96 h.LC_(50)of 24 h,48 h,72 h and 96 h were attained by probit analysis software SPSS Version 16.Fish samples were exposed to different concentrations of trichlorofon(5,10,20 and 40 mg/L)for 96 h and mortality were recorded,separately.Results:The 96 h LC_(50)of Poecilia latipinna,Poecilia reticulata a,Gambusia holbrooki and Xiphophorus helleri were 9.80,9.80,9.95 and 7.99 mg/L,respectively.Conclusions:According to the results of this research,LC_(50)values indicated Xiphophorus helleri was the most resistant and Gambusia holbrooki,with a few differences,was the most sensitive species compared with the fishes examined.
文摘Although the majority of studies on mate choice focus on female mate choice, there is growing recognition of the role of male mate choice too. Male mate choice is tightly linked to 2 other phenomena： female competition for males and ornamentation in females. In the current article, I review the existing literature on this in a group of fishes, Poeciliidae. In this group, male mate choice appears to be based on differences in female quality, especially female size, which is a proxy for fecundity. Some males also have to choose between heterospecific and conspecific females in the unusual mating system of the Amazon molly. In this case, they typically show a preference for conspecific females. Whereas male mate choice is relatively well documented for this family, female ornamentation and female competition are not.
