Construction and behavior of circularly permuted and telocentric chromosomes in Saccharomyces cerevisiae.

We developed techniques that allow us to construct novel variants of Saccharomyces cerevisiae chromosomes. These modified chromosomes have precisely determined structures. A metacentric derivative of chromosome III which lacks the telomere-associated X and Y' elements, which are found at the telomeres of most yeast chromosomes, behaves normally in both mitosis and meiosis. We made a circularly permuted telocentric version of yeast chromosome III whose closest telomere was 33 kilobases from the centromere. This telocentric chromosome was lost at a frequency of 1.6 X 10(-5) per cell compared with a frequency of 4.0 X 10(-6) for the natural metacentric version of chromosome III. An extremely telocentric chromosome whose closet telomere was only 3.5 kilobases from the centromere was lost at a frequency of 6.0 X 10(-5). The mitotic stability of telocentric chromosomes shows that the very high frequency of nondisjunction observed for short linear artificial chromosomes is not due to inadequate centromere-telomere separation.     

Cytogenetic study on Microtus guentheri (Danford and Alston, 1880) (mammalia: rodentia) from Turkey: constitutive heterochromatin distribution and nucleolar organizer regions

Conventionally stained, C- and Ag-NOR banded karyotypes of Guenther's vole, Microtus guentheri were studied from Turkey. The species possesses a karyotype of 2n = 54, NFa = 52 and NF = 54 in specimens from Kahramanmara? and Gaziantep provinces, whereas NF = 56 in females and NF = 55 in males were found in individuals from Kirikkale and Nev?ehir provinces. The X chromosome was a large acrocentric (NF = 54) or submetacentric (NF = 55, 56) while the Y chromosome was a small telocentric in all specimens examined. Blocks of constitutive heterochromatin were located in the pericentromeric areas of autosomes including the X chromosome. Nucleolar organizer regions (NORs) were located at the telomeric regions of the short arms of five acrocentric pairs and centromeric regions of two telocentric pairs in the Nev?ehir and Kirikkale specimens.     

Chromosomal polymorphism in Rattus rattus (L.) collected in Kusudomari and Misima

Summary Chromosomes of Rattus rattus (L.), collected in Kusudomari (Nagasaki) and Misima (Sizuoka) were examined. The karyotype revealed a remarkable heteromorphism in chromosome no. 1. The homozygotic, i.e. standard type, was characterized by 13 pairs of telocentric and 7 pairs of metacentric chromosomes. Chromosome pair no. 1 was telocentric. X and Y chromosomes were also telocentrics. 18.4 per cent of rats from Kusudomari and 40 per cent from Misima showed heteromorphic pair in chromosome no. 1. One chromosome of the heteromorphic pair is conspicuous by the subtelocentric centromere. Total length of the telocentric chromosome of no. 1 is almost the same as of its subtelocentric partner. These facts indicate that the subtelocentric no. 1 chromosome might have arisen by a centromeric inversion of the telocentric chromosome. Individuals homozygous for the subtelocentric no. 1 chromosome could not be found in either population. The difference in the frequency of the dimorphics collected in Kusudomari and Misima was statistically significant. Possible causes of the difference are discussed.Dedicated to Professor H. Bauer on the occasion of his sixtieth birthday. — Contributions from the National Institute of Genetics, Misima, Japan, No. 533     

中国刺猬的染色体研究

本文采用全血培养和骨髓染色体制片法,对分布于我国南京市郊和济南市郊的刺猬染色体进行了组型、C-带、G-带和银染色的观察分析,并与东欧、西欧两种刺猬比较,它们之间的核型及带型差异显著;又将南京、济南及金清波(1985)报道的河南新乡三地分布的刺猬进行比较,它们的核型及带型也显示出一定差异,这种多态性在分类和进化上有一定的意义。     

毛冠鹿种内异染色质变化与染色体多态

采用原代和传代培养方法对8头毛冠鹿(Elaphodus cephalophus)的皮肤细胞进行了染色体研究,发现了一种核型与以前所报道的几种核型不一致,确定为一新核型。在该核型中,染色体众数2n=47,2条X染色体异型,一条为端着丝粒,另一条为近端着丝粒。C-带显示该核型中异染色质除了分布在2条X染色体长臂中之外,在第一对大的端着丝粒染色体中的一条近着丝粒区出现一异染色质“柄”。结合C-带及薄层扫描结果对毛冠鹿种内常染色体、性染色体中异染色质的含量和分布与染色体多态的关系进行了探讨。     

黑线姬鼠华北亚种染色体研究

本文采用骨髓染色体制片法,对分布于山东的黑线姬鼠华北亚种的染色体组型,C-带、G-带和银染核型进行了分析研究。其核型为2n=48=38 T+8 M+XY。X为较小的端着丝粒染色体,Y为组型中最大的染色体。几乎每个常染色体的着丝粒区都具异染色质。性染色体的异染色质丰富。No.10和No.18染色体具NOR(?)。每条染色体都显示出较清晰的G-带。同时对黑线姬鼠精母细胞的减数分裂进行了观察,并将山东标本与欧洲标本的核型进行了比较,其性染色体有显著差异。     

Chromosomal characteristics and karyotype evolution of Oxyopidae spiders (Araneae, Entelegynae)

We made a cytogenetic analysis of four species of Oxyopidae and compared it with the karyotype data of all species of this family. In Hamataliwa sp, the mitotic cells showed 2n♂ = 26+X(1)X(2) and telocentric chromosomes. The 2n♂ = 28, which has been described for only one oxyopid spider, is the highest diploid number reported for this family. Peucetia species exhibited distinct karyotype characteristics, i.e., 2n♂ = 20+X(1)X(2) in P. flava and 2n♂ = 20+X in P. rubrolineata, revealing interspecific chromosome variability within this genus. However, both Peucetia species exhibited telocentric chromosomes. The most unexpected karyotype was encountered in Oxyopes salticus, which presented 2n♂ = 10+X in most individuals and a predominance of biarmed chromosomes. Additionally, one male of the sample of O. salticus was heterozygous for a centric fusion that originated the first chromosomal pair and exhibited one supernumerary chromosome in some cells. Testicular nuclei of Hamataliwa sp and O. salticus revealed NORs on autosomal pairs, after silver impregnation. The majority of Oxyopidae spiders have their karyotype differentiated by both reduction in diploid number chromosome number and change of the sex chromosome system to X type; however, certain species retain the ancestral chromosome constitution 2n = 26+X1X2. The most remarkable karyotype differentiation occurred in O. salticus studied here, which showed the lowest diploid number ever observed in Oxyopidae and the second lowest registered for Entelegynae spiders.     

Chromosomal polymorphism of mandarin vole,Microtus mandarinus (Rodentia)

The mitotic and meiotic chromosomes of mandarin vole, Microtus mandarinus Milne-Edwards, from Shandong Province of China were analyzed by conventional, G- and C-banding and Silver-staining techniques. We detected chromosomal polymorphism in the vole, exhibiting diploid chromosome numbers 2n = 48-50 and variable morphology of the 1st pair, one medium sized telocentric pair and the X chromosomes. Four types of karyotypes were revealed in the population. According to banding analysis, there were pericentric inversion, Robertsonian fusion and translocation in M. mandarinus karyotype evolution. The X displayed two different morphologies, which could be explained by prericentric inversion and a telocentric autosome translocation.     

大仓鼠的核型与B染色体研究

采用骨髓细胞染色体制片法,对分布于山东济南、泰山、东北长白山和陕西西安的大仓鼠的染色体组型、Ｇ－带、Ｃ－带和银染核型进行了分析研究。济南、西安和长白山的标本的二倍体数目和核型相似,２ｎ＝２８,２２ｔ＋４ｍ＋ＸＹ（ｓｔ,ｍ）。泰山标本的二倍体数目为２ｎ＝２８～２９,即在６７５％的中期相中多出了一条形态最小的端着丝粒染色体,这条染色体为Ｂ染色体,可能起源于Ｘ染色体。泰山标本的Ａ染色体组与上述３地标本相同。４地标本的Ｇ－带、Ｃ－带和银染核型相似。除Ｂ染色体外,每个端着丝粒染色体都具有着丝粒异染色质,ＡｇＮＯＲｓ较恒定地出现在Ｎｏｓ２,４,８,９,１３染色体上。也就是说大仓鼠的Ｂ染色体为Ｃ－带阴性,不携带核仁组织者。这种Ｂ染色体Ｃ－带阴性的特征在赤狐、黑家鼠和大林姬鼠朝鲜亚种中亦有报道。     

Polymorphic karyotypes and sex chromosomes in the tufted deer (Elaphodus cephalophus): cytogenetic studies and analyses of sex chromosome-linked genes

Different diploid chromosome numbers have been reported for the tufted deer Elaphodus cephalophus (female, 2n = 46/47; male, 2n = 47/48) in earlier reports. In the present study, chromosomal analysis of seven tufted deer (5 male symbol, 2 female symbol) revealed that the karyotype of these animals contains 48 chromosomes, including a pair of large heteromorphic chromosomes in the male. C-banding revealed these chromosomes to be very rich in constitutive heterochromatin. Chromosome banding and PCR of sex chromosome-linked genes (SRY, ZFX, ZFY) performed on DOP-PCR products of single microdissected X and Y chromosomes confirmed that the large telocentric chromosome without secondary constriction is the X chromosome whereas the subtelocentric chromosome is the Y. The increased size of both, the X and Y chromosome, appears to be at least partially attributable to the presence of substantial amounts of heterochromatin.     

宽耳犬吻蝠(TADARIDA TENIOTIS INSIGNIS)和普氏蹄蝠(HIPPOSIDEROS PRATTI)染色体组型分析

本文分析了宽耳犬吻蝠(Tadarida teniotis insignis Blyth)和普氏蹄蝠(Hipposideros pratti Thomas)的常规核型,现报道如下。     

The founder effect theory: quantitative variation and mdg-1 mobile element polymorphism in experimental populations of Drosophila melanogaster

The chromosomes of 14 specimens of the genus Reithrodon from three different localities of Argentina and two localities of Uruguay were studied using G-and C-banding techniques. Specimens of Uruguay showed a karyotype of 2n=28 chromosomes having a large metacentric X, and a telocentric Y chromosome. This karyotype is very similar to that recently described in a sample from southern Brazil, differing only in the nature of the Y chromosome, which is metacentric in the Brazilian form. All specimens from Argentina showed a 2n=34 karyotype, differing from the Brazilian karyotype by two centric fusions, an acquisition of chromosome material, and at least one pericentric inversion, and by the telocentric nature of both the X and the Y chromosomes. G-and C-banding suggest that the metacentric gonosomes in the Brazilian form resulted from a double autosomal-X-Y Robertsonian translocation. The Uruguayan cytotype is interpreted as derived from a hypothetical neo-X/Y₁Y₂ ancestral form by the secondary loss of the Y₁ chromosome. The karyotypic differences between the Brazilian-Uruguayan and the Argentinian forms afford evidence of species differentiation. It is proposed to assign the former to Reithrodon typicus, and the later to R. auritus.     

Sister chromatid exchange points in the heterochromatin and euchromatin regions of Chinese hedgehog chromosomes

Summary The Chinese hedgehog has a diploid chromosome number of 48 in which there are eleven pairs of telo- or subtelocentric autosomes, twelve pairs of meta- or submetacentric autosomes, a metacentric X chromosome and a telocentric Y chromosome. The heterochromatin is almost completely distributed in five large distal segments of chromosomes nos. 9 to 12 and no. 18. There is no positive C-band in the centromeres of the chromosomes except for the X chromosome which has a small, weakly stained C-band in the centromere. In Chinese hedgehog cells 52.1% of SCEs are found at the junction between the euchromatin and the heterochromatin, 39.5% in the heterochromatin and 8.4% in the auchromatin. The SCE number per unit C-band is double the SCE number per unit euchromatin. The SCE rate in the heterochromatin or euchromatin regions is not proportional to their chromosome length and can be quite different between different pairs of the chromosomes. Our results indicate that there is a non-uniform distribution of the SCEs in the Chinese hedgehog cells.     

东北地区亚洲飞蝗染色体核型分析

采用常规压片法对吉林省亚洲飞蝗Locusta migratoria migratoria(L.)的染色体核型进行分析.研究结果表明:亚洲飞蝗性别决定机制为X0型,染色体数目为2n♂=23,染色体组式4L+4M+3S+X,全部为端部着丝粒染色体,NF=23.染色体中最长(L1)与最短(S11)染色体之比大于4:1,臂比大...     

Precocious Meiotic Centromere Separation of a Novel Yeast Chromosome

In Saccharomyces cerevisiae, a reciprocal translocation between chromosome II and a linear plasmid carrying a centromere (CEN6) has split chromosome II into two fragments: one, approximately 530 kilobase pairs (kbp) in size, has the left arm and part of the right arm of chromosome II; the other, a telocentric fragment approximately 350 kbp in size, has CEN6 and the rest of the right arm of chromosome II. A cross of this yeast strain with a strain containing a complete chromosome II exhibits a high frequency of precocious centromere separation (separation of sister chromatids during meiosis I) of the telocentric fragment. Precocious centromere separation is not due to the position of the centromere per se, since diploids that are homozygous for both fragments of chromosome II segregate the telocentric fragment with normal meiotic behavior. The precocious centromere separation described here differs from previously described examples in that pairing and synapsis of this telocentric chromosome seem to be normal. One model of how centromeres function in meiosis is that replication of the centromere is delayed until the second meiotic division. Data presented in this paper indicate that replication of the centromere is complete before the first meiotic division. The precocious separation of the centromere described here may be due to improper synapsis of sequences flanking the centromere.     

Chromosomes and DNA of Mus: the karyotypes of M. fulvidiventris and M. dunni.

The chromosomes of the Asian mice, Mus fulvidiventris (booduga?), are typical of the Mus in general, viz., 40 telocentric chromosomes. The centromeric heterochromatin does not fluoresce brightly. The G band pattern of the euchromatin is the same as that of M. musculus. The diploid number of M. dunni is also 40, but each autosome possesses a short, heterochromatic second arm. The X chromosome is a long submetacentric, whose entire short arm and the terminal segment of the long arm are heterochromatic. The Y is a long telocentric and is heterochromatic. The G band pattern of the long arms of M. dunni involved only the addition of C bands. Mus dunni and M. booduga are sympatric in many localities in India, but they can be separated by karyological and subtle morphological differences.     

四种菊头蝠染色体组型分析

本文分析了皮氏菊头蝠(R. pearsoni chinensis),鲁氏菊头蝠(R.rouxi sinicus),角菊头蝠(R.cornutus pumilus)及中菊头蝠(R.affinis)的常规核型,现报道如下。     

Karyotypes of Cyprinus carpio and Leuciscus cephalus

Karyological investigations on the common carp (Cyprinus carpio) and chub (Leuciscus cephalus) are described. The diploid chromosome complement in the carp was found to be 98, with 50 meta- to submetacentric chromosomes, 48 subtelo- to telocentric chromosomes, and an arm number of 148. Chromosomal studies on the chub revealed the diploid chromosome complement to be 50, with 34 meta- to submetacentric chromosomes, 16 subtelo- to telocentric chromosomes, and an arm number of 84.     

Stable telocentric chromosomes produced by centric fission in chinese hamster cells in vitro

Metaphase examination of pseudodiploid Chinese hamster cells revealed that spontaneous breaks or fission occurred rather frequently (2.9%) at the centromeric regions of subtelo- or metacentric chromosomes, resulting in the production of telocentric chromosomes. The centromeric fission appeared to occur in every member of the chromosome complement. An attempt was made to isolate cells possessing thus derived telocentrics from the cell population and gave two clonal lines which were retaining one and two telocentric chromosomes, respectively. Both banding and labeling patterns of these chromosomes indicated unequivocally their X chromosome origin. They were transmitted successively to the daughter cells during a 3-month culture period, showing no tendency to fuse to produce a metacentric chromosome.Contribution No. 897 from the National Institute of Genetics, Japan.     

两种泥鳅中PdSox8和PdSox9基因的染色体定位

应用染色体原位杂交技术,以地高辛标记的大鳞副泥鳅ＰｄＳｏｘ８和ＰｄＳｏｘ９基因片段为探针,研究了二者在泥鳅和大鳞副泥鳅染色体组中的定位。结果表明,在大鳞副泥鳅中ＰｄＳｏｘ８、ＰｄＳｏｘ９分别于端部着丝粒染色体第４和第２号即１４和１２染色体上,信号位点距着丝粒的相对距离分别为４０．２％和６７．５％,在泥鳅中,则分别位于ｔ９、ｔ６上,信息位点距着丝粒的相对蹁分别为５８．３％和３０．８％。