Three cases of minor chromosomal aberrations discovered by prenatal chromosome determination.

A case of pronounced secondary constriction of a chromosome belonging to pair N0. 9, a case of deletion of the short arms of one of the chromosomes in pair No. 13, and a case of partial trisomy of the distal portion of a chromosome in pair No. 14 were discovered by prenatal chromosome determination. Analysis of the parents' karyotypes enabled the clinical importance of the three different chromosomal aberrations to be elucidated.     

The trisomy 18 syndrome with an E/G translocation

Summary An infant with a typical Edwards syndrome and a modal chromosome number of 46 is reported. In all cells analyzed one chromosome G was missing and an additional chromosome similar to a pair No. 16 was present. The phenotype of the child indicates that the extra element is a translocation between G and 18 chromosomes as in one case described previously.     

Frequency of chromosome polymorphism in Rattus rattus collected in Japan

This paper deals with a population survey of chromosome polymorphism of Rattus rattus collected in Japan and the results of their test crosses. All the animals had diploid 42 chromosomes, but three chromosome pairs, Nos. 1, 9 and 13, were polymorphic in respect to acro- and subtelocentric chromosomes. Frequency of No. 1 chromosome polymorphism in 453 rats collected in 19 localities showed 343 rats (75.5%) with acrocentric homomorphic pair (A/A), 90 (19.9%) with aerocentric and subtelocentric heteromorphic pair (A/S) and the remaining 20 (4.4%) with subtelocentric homomorphic pair (S/S). All animals collected in northern and northwestern Japan showed only the A/A pair, while those collected in southern and southeastern Japan showed A/A, A/S and S/S polymorphism. The latter group was also classified into 3 populations (east, southeast and south) by the different frequency of the subtelocentric chromosome. Progeny tests revealed that segregation of A/A, A/S and S/S types from F₁ hybrids between various chromosome combinations was not significantly different from the theoretical one. However, the number of animals with A/S pair was always slightly higher than the other two types, while those with S/S pair slightly fewer. Local differences of the chromosome polymorphism in Japan were considered due to the result of migration and selection of the rats with S/S chromosome type.Contribution No. 817 from the National Institute of Genetics, Japan. Supported in part by a grant-in-aid from the Ministry of Education of Japan (Scientific Expedition in 1968, and No. 8801 in 1969).     

大蹄蝠的核型分析

研究了大蹄蝠的核型、C-带和Ag-NORs。大蹄蝠的染色体数目是2n=32,NF=60,No.8染色体上有一明显的次缢痕,大蹄蝠有丰富的结构异染色质,主要以着丝粒带的形式存在;且有若干对染色体部分或全部异染色质化;一对Ag-NORs稳定地出现于No.8染色体。     

水貂的染色体研究

采用复制带、C带和硝酸银染色等分带技术研究了水貂的核型和带型。结果表明,2n=30,枝型为10（M）＋16（SM）＋2（A）,XX（M）。C-带显示该水貂的一些染色体的结构异染色质比较丰富,从着丝粒区域延伸到两臂上,No.5染色体着丝粒结构异染色质有些弱化;X染色体的结构异染色质较常染色体的丰富。Ag-NORs有3个,分布在No.8染色体的次缢痕区域和一条No.2染色体长臂接近着丝粒的区域。     

福建大头蛙的核型及带型分析

利用骨髓细胞蒸气固定法制备染色体标本,研究了福建大头蛙(Limnonectesfujianensis)黄山居群的核型、C 带和Ag NORs。结果表明,福建大头蛙核型为2n =2 2 =2 0M 2SM ,NF =44,次缢痕位于No 1 0q ;各染色体均有着丝粒C 带,3p、9q出现插入型C 带;Ag NORs位于1 0q。     

石貂的染色体研究

本文对分布在我国的石貂北方亚种染色体进行了较详细的研究。结果表明２ｎ＝３８,核型为１４（Ｍ）＋４（ＳＭ）＋１８（ＳＴ）,ＸＹ（Ｍ,Ａ）。Ｃ－带显示该亚种的一些染色体着丝粒区域结构异染色质弱化或消失。Ｎｏ,９染色体的短臂完全异染色质化;Ｘ染色体长臂丰出现插入杂色质带;Ｙ为完全结构异染色质组成。     

Sex Differences in Polymorphism and Expression of AAT-1 in the Hiroshima Population of Buergeria buergeri (Anura, Rhacophoridae)

Buergeria buergeri is female heterozygous in sex determination; chromosome pair No. 7 in this species is a pair of sex chromosomes of the ZZ/ZW type. Genetic analysis of AAT-1 variants was carried out to elucidate the mode of inheritance of this locus by starch-gel electrophoresis using field-caught females and males and their offspring produced by artificial crossings. The results showed that the AAT-1 locus is sex-linked and that alleles are expressed on the Z chromosome, but not the W chromosome. It is evident that the AAT-1 gene of female offspring is hemizygous and that the allele present is on the Z chromosome, which is derived from the male parent.     

The chromosome complement of the slow loris (Nycticebus coucang Boddaert, 1785)

The chromosome complements of two male and two female adult slow lorises (Nycticebus coucang) have been studied in blood cultures cultivatedin vitro for three days. We have observed basic differences in arrangement from previous results, and the existence in the complement of a dimorphic pair not described before in this species. This dimorphic pair does not fit with any known type of chromosome dimorphism or polymorphism, either in rodents or primates. The diploid chromosome number is 50. Nine of the chromosome pairs are metacentric, the remaining 15 pairs, submetacentric. The X chromosome is a long submetacentric, ranking 4 in order of decreasing size. The Y chromosome is a rather long metacentric and ranks 15 in the same order. The autosomes, 2 to 10µ long in metaphase with arm ratios ranging from 1.14 to 2.65, are paired and arranged in order of decreasing size. Chromosome pair No. 5 is dimorphic, one of the chromosomes in the pair being constantly longer than the other. An idiogram of the haploid chromosome complement is presented, incorporating measurements of 30 analyzed nuclei.     

沼泽水牛与摩拉水牛杂种一代精母细胞联会复合体分析

应用界面铺张——硝酸银染色技术,对沼泽水牛和摩拉水牛杂种一代精母细胞联会复合体（SC）进行电镜观察。结果表明,在减数分裂粗线期,杂种水牛精毋细胞中形成22条正常的常染色体SC,一个中着丝粒/亚中着丝粒/端着丝粒三价体和XY双价体。这表明沼泽水牛和摩拉水牛的染色体具有高度的同源性,沼泽水牛1号染色体是由摩拉水牛4号、9号染色体串联易位而形成。     

同一生境下多年生黑麦草与节节麦的核型比较

对同一生境下多年生黑麦草（Lolium perenn L.）和节节麦（Aegilops squarrosa L.）的根尖细胞染色体作了分析,并从细胞学角度比较了两者的同源性。结果表明：多年生黑麦草的核型公式为：2n=6x=42=24m＋18sm（2SAT）,属于六倍体的＂2B＂型,在第19号染色体上有一对随体,最长与最短染色体的比为2.13,臂比大于2的染色体占全套染色体的30%,核型不对称系数为60.48%;节节麦的核型公式为2n=2x=14=10m＋4sm（2SAT）,属于二倍体的＂2A＂型,在第4号染色体有一对随体,最长与最短染色体长度比为1.49,臂比大于2的染色体占全套染色体的14%,不对称系数为58.2%,表明同一生境下多年生黑麦草比节节麦更为进化,两者在染色体水平上没有亲缘关系。     

赤链华游蛇的染色体组型与银带带型研究

该文研究赤链华游蛇的染色体组型与NOR     

Karyotypic differences of black rats,Rattus rattus,collected in various localities of East and Southeast Asia and Oceania

Karyotypes of several subspecies of black rats, Rattus rattus, collected in different localities of Asia and Oceania were examined with special emphasis on the relationship between the chromosome polymorphism and differentiation of the subspecies. Subspecies of black rats (R. rattus) collected were as follows; tanezumi from Japan; flavipectus and sladeni from Hong Kong; diardii, jalorensis from Kuala Lumpur, Malaysia; argentiventer from Kuala Lumpur, and Java and Celebes, Indonesia; mindanensis from Luzon and Mindanao, Philippines; and rattus from Australia, New Zealand, and New Guinea. Subspecies in Formosa, Korea and Thailand were not determined. All black rats collected in the above Asian districts had 42 diploid chromosomes, while those in Oceania had 38. The rats collected in Japan (tanezumi), Korea, Formosa, Thailand and Malaysia (diardii) had A/A No. 1 pair or polymorphic No. 1 (A/A, A/S and S/S) pairs, while those collected in Java and Celebes (argentiventer), Luzon and Mindanao (mindanensis) showed a higher frequency of S/S No. 1 pair. From the higher occurrence of No. 1 A/A pair of black rats in the Asian continent where the black rats originated, it is suggested that the original type of No. 1 chromosome pair of the black rats is A/A, and a pericentric inversion occurred in the acrocentric No. 1 chromosome and thus rats with subtelocentric No. 1 pair formed.—Black rats with 38 chromosomes were observed in Australia, New Guinea and New Zealand. These karyotypes seem to have developed by Robertsonian fusion of 4 acrocentric pairs (No. 4 and 7, and No. 11 and 12) in black rats of the Asian type. A relationship between body size and chromosome constitution was observed in subspecies of the black rats.Contribution No. 831 from the National Institute of Genetics, Japan. Supported by a grant-in-aid from the Ministry of Education of Japan (Scientific Expedition in 1968, No. 8801 in 1969, and No. 9001 in 1970).     

The relationship between chromosomal aberrations, survival and DNA repair in tumour cell lines of differential sensitivity to X-rays and sulphur mustard

A pair of cultured rat lymphosarcoma cell lines (Yoshida) with a pronounced differential sensitivity to killing with sulphur mustard (SM), but with the same sensitivity to X-rays, was examined for chromosome damage and DNA repair replication after treatment with these agents. A pair of mouse lymphoma cell lines (L5178Y) with a differential sensitivity to X-rays was similarly investigated.SM-resistant Yoshida cells suffered much less chromosome damage than sensitive cells in spite of equal alkylation of DNA, RNA and protein in sensitive and resistant cells. The pair of Yoshida cell lines sustained the same amount of chromosome damage after X-irradiation. Much less chromosome damage was observed in the radiation-resistant lymphoma cell line than in the sensitive line after X-irradiation.No differences was found between the pairs of cell lines in their capacities for repair replication after SM or X-ray treatment.Thus, the drug and radiation resistance is accompanied by, and perhaps mediated through, a reduced amount of induced chromosome damage but is not quantitatively related to the capacity for DNA repair replication.Apart from small differences in modal chromosome numbers there are no obvious karyotype differences between the sulphur mustard-sensitive and -resistant Yoshida cells or between the radiation-sensitive and -resistant lymphoma cells.     

Chromosome studies in the red howler monkey, Alouatta seniculus stramineus (Platyrrhini, Primates): description of an X1X2Y1Y2/X1X1X2X2 sex-chromosome system and karyological comparisons with other subspecies

In the red howler monkey, Alouatta seniculus stramineus (2n = 47, 48, or 49), variations in diploid chromosome number are due to different numbers of microchromosomes. Males exhibit a Y;autosome translocation involving the short arm of an individual biarmed autosome. Consequently, the sex-chromosome constitution in the male is X1X2Y1Y2, with X1 representing the original X chromosome, X2 the biarmed autosome (No. 7), Y1 the Y;7p translocation product, and Y2 the acrocentric homolog of 7q. In the first meiotic division, a quadrivalent with a chain configuration can be observed in spermatocytes. Females have an X1X1X2X2 sex-chromosome constitution. Chromosome heteromorphisms were observed in pair 13, due to a pericentric inversion, and pair 19, due to the presence of constitutive heterochromatin. Microchromosomes, which varied in number between individuals, were also heterochromatic. NOR-staining was observed at two separate sites on a single chromosome pair (No. 10). A comparison of A.s. stramineus with A.s. macconnelli shows that these two subspecies have identical diploid chromosome numbers (47, 48, or 49), again due to a varying number of microchromosomes, and that they share a similar sex-chromosome constitution. Their karyotypes, however, are not identical, but can be derived from each other by a reciprocal translocation. Further comparisons with other A. seniculus subspecies reported in the literature indicate that this taxon is not karyologically uniform and that substantial chromosome shuffling has occurred between populations that have been considered to be subspecies by taxonomic criteria based on their morphometric attributes.     

THE CHROMOSOMES OF SPLNACIA OLERACEA

Ellis , J. R., and Jules Janick . (Purdue U., Lafayette, Ind.) The chromosomes of Spinaeia oleracea. Amer. Jour. Bot. 47(3) : 210—214. Illus. 1960.—The somatic chromosomes of S. oleracea are described and each has been associated with one of the 6 morphological trisomics derived from triploid-diploid crosses. Of these 6 primary trisomies, reflex had been shown by genetic studies to be trisomic for the chromosomes carrying the sex-determining factors. This chromosome is the longest of the somatic complement and has a sub-median centromere. No obvious heteromorphism of this chromosome pair was observed in staminate plants. Heteromorphism involving this chromosome pair has been reported recently in 2 varieties of cultivated spinach by Zoschke (1956) and Dressier (1958) and was earlier reported by Araratjan (1939) for the wild species, S. tetandra. However, their accounts differ markedly from each other and with the present results in respect to the morphology of this chromosome pair. This study suggests the existence of races which differ with respect to the morphology of the chromosome pair containing the X Y factors.     

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     

不同地理区域鲫鱼染色体银染核仁组织者的比较研究

本文对不同地理区域的鲫鱼(Carassius auratus)—滇池高背鲫、低背鲫、方正银鲫(C.auratusgibelio)的核型及核仁组织者NORs进行了比较研究,并对高背鲫来源作些初步探讨,结果如下: 1.低背鲫Carassius auratus (back low type):2n=100,22m+30sm+48t.st,NORs=4,出现于第5—6对亚中着丝粒染色体短臂。 2.滇池高背鲫Carassius auratus(back high type):2n=156,30m+46sm+80t.st,NORs=6,出现于第5—7对亚中着丝粒染色体短臂。 3.方正银鲫C.auratus gibelio:2n=162,32m+52sm+78t.st NORs=4,出现于第5—6对亚中着粒染色体短臂。     

Differing requirements for RAD51 and DMC1 in meiotic pairing of centromeres and chromosome arms in Arabidopsis thaliana

During meiosis homologous chromosomes pair, recombine, and synapse, thus ensuring accurate chromosome segregation and the halving of ploidy necessary for gametogenesis. The processes permitting a chromosome to pair only with its homologue are not fully understood, but successful pairing of homologous chromosomes is tightly linked to recombination. In Arabidopsis thaliana, meiotic prophase of rad51, xrcc3, and rad51C mutants appears normal up to the zygotene/pachytene stage, after which the genome fragments, leading to sterility. To better understand the relationship between recombination and chromosome pairing, we have analysed meiotic chromosome pairing in these and in dmc1 mutant lines. Our data show a differing requirement for these proteins in pairing of centromeric regions and chromosome arms. No homologous pairing of mid-arm or distal regions was observed in rad51, xrcc3, and rad51C mutants. However, homologous centromeres do pair in these mutants and we show that this does depend upon recombination, principally on DMC1. This centromere pairing extends well beyond the heterochromatic centromere region and, surprisingly, does not require XRCC3 and RAD51C. In addition to clarifying and bringing the roles of centromeres in meiotic synapsis to the fore, this analysis thus separates the roles in meiotic synapsis of DMC1 and RAD51 and the meiotic RAD51 paralogs, XRCC3 and RAD51C, with respect to different chromosome domains.     

Non-condensation of one segment of a chromosome No. 2 in a male with an otherwise normal karyotype (and severe hypospadias)

Summary A child with severe hypospadias is presented, whose karyotype showed in about 11% of mitoses of peripheral blood one member of chromosome pair No. 2 with a non-condensed region near the centromere. The non-condensed segment does not show late replication, however, it is situated very close to the late replicating segment of the long arms of chromosome No. 2. The nature and possible implications of this kind of aberration are discussed. It is held that non-condensation can produce localized chromosome breaks by a mechanism possibly different from any of the classical breakage mechanisms.