黄山北草核的核型和G带带型研究

本文研究了北草晰的核型和G带带型,结果表明,北草蝴的染色体数2。二38,由18对常染色休和 1对性染色休组成．常染色体可分成三组：1组有2对染色体;11组包括15对染色体;而川组仅含 1对微小染色体。性染色体为ZW型．这个种的染色体均为端部着丝粒,其AN二38包括1对Z染色 体）,从核型特征上看,可能是晰蝎类中较原始的种。从G带显示结果可见,北草晰的各染色体对均有 其特有的带型,容易辨别。     

南草蜥核型的初步研究

南草蜥眼斑亚种 (Ｔａｋｙｄｒｏｍｕｓｓｅｘｌｉｎｅａｔｕｓｏｃｅｌｌａ ｔｕｓ)隶属于蜥蜴科 (Ｌａｃｅｒｔｉｄａｅ)草蜥属。该属我国已知有 8种〔1〕,其中只北草蜥 (Ｔ ｓｅｐｔｅｎｔｒｉｏｎａｌｉｓ) 〔2〕和白条草蜥 (Ｔ .ｗｏｌｔｅｒｉ) 〔3〕见有核型数据。南草蜥在我国分布于福建、湖南、贵州、云南、广东、海南和广西 ,其核型未见有人报道。本文对♂性南草蜥的核型作了初步研究。1　材料和方法实验动物南草蜥 2♂ ,采自福州仓山。采用骨髓细胞直接制备染色体标本。着丝粒位置按Ｌｅｖａｎ等(1 964 )的标准确定。2　结果和分…     

原尾蜥虎和光蜥的核型研究

该文用骨髓细胞直接制备染色体标本,分析了原尾蜥虎和光蜥的核型,原尾蜥虎２ｎ＝４６,ＮＦ＝４６,染色体组内没有划分大染色体和微小染色体的明显界限,光蜥２ｎ＝２６,ＮＦ＝４２,含４对大染色体和９对小染色体,属两性核型。二者都未发现异型性染色体。     

草晰属两种蜥蜴卵和幼体特征的比较研究

比较研究了南草蜥实验条件下的卵及幼体特征。南草蜥产卵雌体的体长、最大窝卵数、平均卵重小于北草蜥,相对放重与北草蜥相似。两种蜥蜴均通过增加卵长径和卵短径来增加卵重,但卵处形明显不同,南草蜥的卵孵化过程中均吸水增重。相同孵化温度（２６℃）条件下,南草蜥的孵化期明显比北草蜥长。南草蜥幼体的体重、体长、头长和头宽的实测值小于北草蜥,尾长实测值与是蜥显著差异。南草晰幼体的体重、头长和头宽的矫正平均值小于北草     

草蜥属两种蜥蜴卵和幼体特征的比较研究

比较研究了南草蜥和北草蜥实验条件下的卵及幼体特征。南草蜥产卵雌体的体长、最大窝卵数、平均卵重小于北草蜥 ,相对窝卵重与北草蜥相似。两种蜥蜴均通过增加卵长径和卵短径来增加卵重 ,但卵外形明显不同 ,南草蜥的卵较长。两种蜥蜴卵孵化过程中均吸水增重。相同孵化温度 ( 2 6℃ )条件下 ,南草蜥的孵化期明显比北草蜥长。南草蜥幼体的体重、体长、头长和头宽的实测值小于北草蜥 ,尾长实测值与北草蜥无显著差异。南草蜥幼体的体重、头长和头宽的矫正平均值小于北草蜥 ,尾长矫正平均值大于北草蜥 ,体长矫正平均值与北草蜥无显著差异。     

荒漠麻蜥的染色体核型观察

采用常规骨髓细胞制片法,对采自甘肃省民勤县的荒漠麻蜥Eremias przewalskii染色体核型进行分析。荒漠麻蜥染色体核型为2n=38=36I+2m,具18对大型端部着丝粒型和1对微小染色体,属丽斑麻蜥型,与蜥蜴科和麻蜥属的染色体核型一致。系统整理已报道的麻蜥属核型资料,在此基础上探讨麻蜥属的染色体核型特征与演化。     

基于12S rRNA基因序列探讨崇安地蜥的分类地位

为探讨崇安地蜥Platyplacous sylvaticus的分类地位,测定了崇安地蜥线粒体12S rRNA基因全序列,并从GenBank中下载了东亚产10种草蜥、3种地蜥的同源序列进行分析,采用Mega V2.1软件的NJ法和ME法、PAUP4.0软件的MP法构建分子系统树.结果表明:崇安地蜥线粒体12S rRNA基因全序列(952 bp)中T、C、A、G碱基含量分别为23.1%、22.9%、35.9%、18.1%;与其它同源序列比对后有978 bp,发现321个位点出现变异,占总位点数32.8%,其中199个简约信息位点,为总变异位点的62%;转换/颠换之比平均为2.16.构建的分子系统树中,NJ树和ME树完全一致,与MP树略有差异.3种构树法中崇安地蜥与南台草蜥Takydromus sauteri、峨眉地蜥P.intermedius、先岛地蜥P.dorsalis均聚为一支,崇安地蜥与先岛地蜥亲缘关系最近.本实验结果支持将地蜥属并入草蜥属和取消地蜥亚属的观点.     

原尾蜥虎的核型和Ag-NORs研究

对原晰虎进行了核型和核仁组织者（NORs)研究,表明原尾蜥虎的2n=46,全部由23对各级大小的端着丝粒染色体组成,染色体由大至小排列,其长度依次递减,没有大染色体和小染色体的明显界限,未发现异形性染色体对。原尾蜥虎有一对Ag-NORs位于No.2的端丝粒染色体的近端区。     

北草蜥几种消化酶活力比较

应用酶学分析法测定了越冬后北草蜥胃、肠组织中蛋白酶、淀粉酶、纤维素酶的活力。结果表明 ,不同年龄、性别的北草蜥同一组织中消化酶活力有显著差异 ;不同地理种群的北草蜥同一组织中消化酶活力有显著差异 ;不同消化酶在北草蜥同一组织中的活力有显著差异 ;在北草蜥不同的组织中同一消化酶的活力有显著差异。说明北草蜥消化酶的活力与年龄、性别、部位和地理环境等因素有关 ,受食物组成、能量需求和遗传等因素的影响 ,产生了不同的酶活力和分布。这也说明生物长期适应环境 ,形成了不同的代谢水平     

广东省蜥蜴类一新记录——北草蜥

2001年5月,笔者在广东省乳源瑶族自治县大桥镇进行蜥蜴类动物调查时捕捉到8条活体蜥蜴标本,经鉴定为蜥蜴蝌草蜥属北草蜥(Takydromus septentronalis),是广东省爬行动物蜥蜴类的新记录,标本现保存于韶关学院英东生物工程学院动物标本室.现报道如下.     

Identification of the sex chromosome pair in chum salmon (Oncorhynchus keta) and pink salmon (Oncorhynchus gorbuscha)

Fluorescence in situ hybridization (FISH) using a probe to the male-specific GH-Y (growth hormone pseudogene) was used to identify the Y chromosome in the karyotypes of chum salmon (Oncorhynchus keta) and pink salmon (Oncorhynchus gorbuscha). The sex chromosome pair is a small acrocentric chromosome pair in chum salmon and the smallest metacentric chromosome pair in pink salmon. Both of these chromosome pairs are morphologically different from the sex chromosome pairs in chinook salmon (Oncorhynchus tshawytscha) and coho salmon (Oncorhynchus kisutch). The 5S rRNA genes are on multiple chromosome pairs including the sex chromosome pair in chum salmon, but at the centromeres of two autosomal metacentric pairs in pink salmon. The sex chromosome pairs and the chromosomal locations of the 5S rDNA appear to be different in all five of the North American Pacific salmon species and rainbow trout. The implications of these results for evolution of sex chromosomes in salmonids are discussed.     

C-banding and FISH in chromosomes of the blow flies Chrysomya megacephala and Chrysomya putoria (Diptera, Calliphoridae)

The blow flies Chrysomya putoria and C. megacephala have 2n=12 chromosomes, five metacentric pairs of autosomes and an XX/XY sex chromosome pair. There are no substantial differences in the karyotype morphology of these two species, except for the X chromosome which is subtelocentric in C. megacephala and metacentric in C. putoria and is about 1.4 times longer in C. putoria. All autosomes were characterized by the presence of a C band in the pericentromeric region; C. putoria also has an interstitial band in pair III. The sex chromosomes of both species were heterochromatic, except for a small region at the end of the long arm of the X chromosome. Ribosomal genes were detected in meiotic chromosomes by FISH and in both species the NOR was located on the sex chromosomes. These results confirm that C. putoria was the species introduced into Brazil in 1970s, and not C. chloropyga as formerly described.     

Chromosome banding homologies in three species of Aedes (Stegomyia)

The chromosome complements of the mosquitoes Aedes aegypti, Aedes mascarensis, and Aedes albopictus, belonging to the subgenus Stegomyia, gave a uniform response to the Q-, H-, and R-banding techniques. Of the three homomorphic chromosome pairs, only the shortest or sex pair (I) showed a consistent banding pattern. In the three species, a bright yellow intercalary band was present on one arm of both chromosomes of the sex pair after heat treatment and staining with acridine orange. The rest of the chromosome and the other two pairs fluoresced orange-red. The same intercalary region appeared completely dark with the fluorochromes quinacrine and Hoechst 33258, while the rest of the chromosomes fluoresced dull. The same banding pattern was present in males and females. Size variations of the Q- and H-negative and R-positive intercalary bands were observed within each species. The results are interpreted in terms of structural homology of the sex-determining chromosomes, which is retained within the subgenus.     

Sequence differentiation associated with an inversion on the neo-X chromosome of Drosophila americana

Sex chromosomes originate from pairs of autosomes that acquire controlling genes in the sex-determining cascade. Universal mechanisms apparently influence the evolution of sex chromosomes, because this chromosomal pair is characteristically heteromorphic in a broad range of organisms. To examine the pattern of initial differentiation between sex chromosomes, sequence analyses were performed on a pair of newly formed sex chromosomes in Drosophila americana. This species has neo-sex chromosomes as a result of a centromeric fusion between the X chromosome and an autosome. Sequences were analyzed from the Alcohol dehydrogenase (Adh), big brain (bib), and timeless (tim) gene regions, which represent separate positions along this pair of neo-sex chromosomes. In the northwestern range of the species, the bib and Adh regions exhibit significant sequence differentiation for neo-X chromosomes relative to neo-Y chromosomes from the same geographic region and other chromosomal populations of D. americana. Furthermore, a nucleotide site defining a common haplotype in bib is shown to be associated with a paracentric inversion [In(4)ab] on the neo-X chromosome, and this inversion suppresses recombination between neo-X and neo-Y chromosomes. These observations are consistent with the inversion acting as a recombination modifier that suppresses exchange between these neo-sex chromosomes, as predicted by models of sex chromosome evolution.     

Insights into the meiotic behavior and evolution of multiple sex chromosome systems in spiders

A characteristic feature of spider karyotypes is the predominance of unusual multiple X chromosomes. To elucidate the evolution of spider sex chromosomes, their meiotic behavior was analyzed in 2 major clades of opisthothele spiders, namely, the entelegyne araneomorphs and the mygalomorphs. Our data support the predominance of X(1)X(2)0 systems in entelegynes, while rare X(1)X(2)X(3)X(4)0 systems were revealed in the tuberculote mygalomorphs. The spider species studied exhibited a considerable diversity of achiasmate sex chromosome pairing in male meiosis. The end-to-end pairing of sex chromosomes found in mygalomorphs was gradually replaced by the parallel attachment of sex chromosomes in entelegynes. The observed association of male X univalents with a centrosome at the first meiotic division may ensure the univalents' segregation. Spider meiotic sex chromosomes also showed other unique traits, namely, association with a chromosome pair in males and inactivation in females. Analysis of these traits supports the hypothesis that the multiple X chromosomes of spiders originated by duplications. In contrast to the homogametic sex of other animals, the homologous sex chromosomes of spider females were already paired at premeiotic interphase and were inactivated until prophase I. Furthermore, the sex chromosome pairs exhibited an end-to-end association during these stages. We suggest that the specific behavior of the female sex chromosomes may have evolved to avoid the negative effects of duplicated X chromosomes on female meiosis. The chromosome ends that ensure the association of sex chromosome pairs during meiosis may contain information for discriminating between homologous and homeologous X chromosomes and thus act to promote homologous pairing. The meiotic behavior of 4 X chromosome pairs in mygalomorph females, namely, the formation of 2 associations, each composed of 2 pairs with similar structure, suggests that the mygalomorph X(1)X(2)X(3)X(4)0 system originated by the duplication of the X(1)X(2)0 system via nondisjunctions or polyploidization.     

蝙蝠科七种蝙蝠的核型

报道了贵州7 种蝙蝠科蝙蝠的核型。伏翼和印度伏翼的染色体数为2n = 26 , 常染色体都由10 对双臂染色体和2 对微小点状染色体组成, N.F = 44 , 性染色体是大小悬殊的端着丝粒染色体; 两者核型的主要区别在于前者的No.3 是中着丝粒染色体, 后者为亚中着丝粒染色体; 大鼠耳辐(四川亚种) 、水鼠耳蝠和西南鼠耳蝠的染色体数都是2n = 44 , 常染色体都由4 对中着丝粒染色体和17 对端着丝粒染色体组成, N.F = 50 , 其中大鼠耳蝠(四川亚种) 和水鼠耳蝠核型非常相似, 西南鼠耳蝠与前二者有一定区别; 山蝠(福建亚种) 是2n = 36 , 常染色体包括7 对中着丝粒染色体、1 对亚中着丝粒染色体和9 对端着丝粒染色体, N.F = 50 ; 南蝠2n = 50 , 常染色体由24 对端着丝粒染色体组成, N.F = 48 , X染色体是最大的中着丝粒染色体。     

Cytogenetic characterization of alpaca (Lama pacos, fam. Camelidae) prometaphase chromosomes

The present study provides specific cytogenetic information on prometaphase chromosomes of the alpaca (Lama pacos, fam. Camelidae, 2n = 74) that forms a basis for future work on karyotype standardization and gene mapping of the species, as well as for comparative studies and future genetic improvement programs within the family Camelidae. Based on the centromeric index (CI) measurements, alpaca chromosomes have been classified into four groups: group A, subtelocentrics, from pair 1 to 10; group B, telocentrics, from pair 11 to 20; group C, submetacentrics, from pair 21 to 29; group D, metacentrics, from pair 30 to 36 plus sex chromosomes. For each chromosome pair, the following data are provided: relative chromosome length, centromeric index, conventional Giemsa staining, sequential QFQ/C-banding, GTG- and RBG-banding patterns with corresponding ideograms, RBA-banding and sequential RBA/silver staining for NOR localization. The overall number of RBG-bands revealed was 391. Nucleolus organizer-bearing chromosomes were identified as pairs 6, 28, 31, 32, 33 and 34. Comparative ZOO-FISH analysis with camel (Camelus dromedarius) X and Y painting probes was also carried out to validate X-Y chromosome identification of alpaca and to confirm close homologies between the sex chromosomes of these two species.     

Chromosome painting supports lack of homology among sex chromosomes in Oncorhynchus, Salmo, and Salvelinus (Salmonidae)

The sex chromosome pair has been identified previously as the largest submetacentric pair in the genome in several species of the genus Salvelinus (eastern trouts and chars) including S. namaycush (lake trout) and as a large subtelocentric/acrocentric pair in several species of the genus Oncorhynchus (Pacific trouts and salmon). Sex chromosomes have not been identified in Salmo (Atlantic salmon and brown trout). Two paint probes, one specific for the short arm (Yp) and the other for the long arm (Yq) of the sex chromosome pair in Salvelinus namaycush were hybridized to chromosomes of Oncorhynchus mykiss (rainbow trout) and O. tshawytscha (chinook salmon) and Salmo salar (Atlantic salmon) and S. trutta (brown trout). The two probes hybridized to two different autosomal pairs in each of the Oncorhynchus species, supporting lack of homology between the sex chromosomes in the two genera. The Yp probe hybridized to interstitial regions on two different chromosome pairs in S. salar and one pair in S. trutta. The Yq probe hybridized to a different pair in both species.     

The karyotype of the golden monkey (Rhinopithecus r. roxellanae)

In this paper, the karyotype and G-banding pattern of the chromosomes of cultured peripheral blood lymphocytes in R. r. roxellanae were investigated. The chromosome number of this species is 44 in both sexes. In R. r. roxellanae, as in other monkeys, sex is determined by specific sex chromosomes, i.e. the male is XY and the female is XX. The 21 pairs of autosomes consist of 7 pairs of metacentric chromoomes, 13 pairs of submetacentric chromosomes and one acrocentric pair. Chromosome measurements were made from highly enlarged photographic prints. They included the relative length, arm ratio and centromere index of each chromosome. Both chromosomal and chromatid aberrations were observed. They were 0·67 and 2%, respectively. Finally, G-banding pattern analysis of chromosomes of R. r. roxellanae were carried out. The results show that each homologous pair has its own special banding pattern, so that each of them is easily recognizable. Idiograms of chromosome complements with the Giemsa banding pattern are constructed.     

Karyotypes of Rana tagoi Okada with diploid number 28 in the Chausu Mountains of the Minamishinshu district of Nagano Prefecture, Japan (Anura: Ranidae)

Karyotypes of Tago's brown frog Rana tagoi from the Chausu mountains in Minamishinshu of Nagano Prefecture were examined by conventional Giemsa staining, C-banding and late replication (LR)-banding. Chromosome number was 2n = 28 in all cases. The 28 chromosomes consisted of four pairs (1-4) of large biarmed chromosomes, two pairs (5-6) of telocentric chromosomes and eight pairs (7-14) of small biarmed chromosomes. Chromosome pair 11 had a secondary constriction on the long arm. In females, the C-band on the long arm of chromosome pair 6 was detected in both homologs, but was absent from the arms of the homologs of chromosome pairs 5 and 9. In males, C-bands were found in the long arms of both homologs of chromosome pairs 5 and 6, were present only in one homolog of chromosome pair 5 for certain male specimens and found in only one homolog of chromosome pair 9. Specimens of R. tagoi (2n = 28) should thus have two pairs of telocentric chromosomes to provide the same number of chromosome arms, these originating quite likely from chromosome pair 1 in the 26-chromosome specimens by centric fission. Heteromorphic sex chromosomes of the XX-XY type in R. tagoi (2n = 28) in the Chausu mountains were identified. Karyotypes of tail-tip cells from a hybrid tadpole between female R. tagoi (2n = 26) from the Hinohara village in Tokyo and male R. tagoi (2n = 28) from the Chausu mountain population were examined by squash preparation. Chromosome number was 2n = 27 in all tadpoles. The 27 chromosomes consisted of one chromosome set of R. tagoi (2n = 28) and one of R. tagoi (2n = 26).