Localization of the porcine growth hormone gene to chromosome 12pl.2 p1–5

Summary
The gene encoding the porcine growth hormone (GH) has been localized to the q-arm of chromosome 12 using high-resolution R-banded chromosomes for in situ hybridization. We report here the localization of GH on the p-arm of this chromosome when using in situ hybridization on high-resolution G-banded chromosomes. Sequential Q- and R-banding show that this discrepancy is caused by a reversed orientation of chromosome 12 in the R-banded high-resolution karyotype published by Rønne et al. (1987) and the G-banded standard karyotype.     

Comparison between the G-banded karyotype of the aoudad (Ammotragus lervia) and sheep (Ovis aries)

Karyotypes of the aoudad and sheep were compared on the basis of G-banded chromosomes at the 450 band level. The common G-banded karyotype showed the homology of all aoudad chromosomes (2n=58) with sheep chromosomes (2n=54) or sheep chromosome arms. The results of cytogenetic investigations suggest that in this case karyotype evolution has led to reduction in chromosome number as a result of centric fusions. The formation of the first metacentric chromosome occurred in the aoudad. The homology of the G-banding pattern in sheep and aoudad suggests the conservation in linear arrangement of genetic material. Thus comparative cytogenetics can be a useful tool in gene mapping.     

臭鼩染色体的研究

本文采用骨髓染色体制片法,对捕自我国浙江萧山市的臭鼩进行了组型、G-带、C-带和核仁组织区银染的观察分析。结果表明,我国臭鼩染色体数目为2n=40,组型为8(m)+2(sm)+10(st)+18(t),性染色体为,(?):X(m或sm),Y(m或sm);♀:XX(m或sm)。G-带较为丰富,每一对染色体都有其特定的带型,较易于辨别与配对。在C-带方前,4对中间着丝粒染色体与5对亚端着丝粒染色体均具有不同程度的着丝粒带,1对亚中着丝粒染色体与9对端着丝粒染色体缺乏C-带物质,性染色体具丰富的远端带及中间带.银染的结果显示,第5、12和13对染色体具银染物质。     

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。     

X/XY/XYY mosaicism as a cause of subfertility in boars: a single case study

Sex chromosome abnormalities are common in mammals and humans and are often associated with subfertility. In this study a boar with normal sperm parameters was indicated to have reduced prolificacy from figures obtained for return rate, farrowing rate and total number of piglets born. G-banded cytogenetic analysis of peripheral blood identified an abnormal mosaic sex chromosome constitution 39,XYY[74]/38,XY[23]/37,X[3]. Cytogenetic analysis of fibroblasts confirmed this mosaic karyotype with similar percentages of cell lines observed 39,XYY[76]/38,XY[19]/37,X[5]. External genitalia revealed a poorly developed scrotum with the right testicle being smaller than the left. To the best of our knowledge this is the first time that this chromosome constitution has been reported in the pig. It is of particular interest that this karyotype is associated with reduced boar fertility, which could lead to potential economic losses if such a boar were selected for breeding purposes.     

A simple statistical analysis of Indian muntjac Giemsa band patterns.

Indian Muntiacus muntjac G-banded chromosomes were used for computerized analysis for standardized karyotype generation. Individual chromosomes on high-contrast photographic negatives were scanned densitometrically. Alignment of each chromosome for analysis was achieved by locating predominant peaks as well as the centromere. This provided better alignment that the use of the chromosome-end locations. The standardized set was obtained by determing the root-mean-square average density along 10-20 homologous chromosomes. The resulting standard karyotype differs from those published earlier. Prophase chromosomes exhibited greater detail than more condensed metaphase chromosomes. Although Indian muntjac chromosomes were used as a model, the method of analysis should be readily adaptable for examining chromosomes of any origin. The analytic technique should be within the capabilities of the smallest cytogenetic laboratories.     

Characterization of G-banded chromosomes of a female saola (Pseudoryx nghetinhensis,2n = 50) and X chromosome i dentification by means of fluorescent in situ hybridization

The saola (Pseudoryx nghetinhensis) is a newly discovered large mammal species, belongs to the subfamily Bovinae and is listed as being endangered. Due to the limitation of the material available, no cytogenetic studies have been carried out on this species. In the present study, preliminary cytogenetic analysis was undertaken on cultured female fibroblast cells to characterize the karyotype organization of saola. An examination of 120 Giemsa stained metaphases showed the diploid chromosome number of 2n = 50, including five bi-armed chromosome pairs. The distribution of constitutive heterochromatin in saola was studied. However, the variability in the size of C-bands was not significant on all the homologous chromosomes. The X chromosome pair, corresponding to the largest telocentric chromosomes, was identified by fluorescent in situ hybridization (FISH) using a bacterial artificial chromosome clone (BAC 0577G05, which maps to BTAXq25-->q33). In comparison to the standard karyotype of cattle (ISCNDB 2000), a G-banded ideogram of saola (about 390 band level) was presented. This work, therefore, provided a basic insight into the karyotype organization of this endangered species and will be particularly useful to improve the understanding of differences of genomes between related species.     

Establishment of an R-banded rabbit karyotype nomenclature by FISH localization of 23 chromosome-specific genes on both G- and R-banded chromosomes

Direct detection of fluorescent in situ hybridization signals on R-banded chromosomes stained with propidium iodide is a rapid and efficient method for constructing cytogenetic maps for species with R-banded standard karyotypes. In this paper, our aim is to establish an R-banded rabbit karyotype nomenclature that is in total agreement with the 1981 G-banded standard nomenclature. For this purpose, we have produced new GTG- and RBG-banded mid-metaphase karyotypes and an updated version of ideograms of R-banded rabbit chromosomes. In addition, to confirm correlations between G- and R-banded chromosomes, we have defined a set of 23 rabbit BAC clones, each containing a specific gene, one marker gene per rabbit chromosome, and we have localized precisely each BAC clone by FISH on both G- and R-banded chromosomes.     

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。     

Immortalized cell lines from murine embryos are characterized by progressive destabilization of their karyotype structure

The karyotype structure was studied for three cell lines obtained from cells of transgenic murine embryos at early stages of their establishment. The first line was obtained from a transgenic embryonic explantant containing oncogen v-sis under promotor MMTV, two other lines originated from cells of transgenic embryos containing oncogen k51. The karyotypic analysis of G-banded metaphase chromosomes revealed deviations from the normal mouse karyotype as early as by the third passage of cultivation of independent embryonic cell lines that contained a foreign oncogene in their genome. The repeated analysis that involved 15-22 passages revealed similar abnormalities: variability and progression in chromosome number with the appearance of hyperpolyploid combinations, and a large number of rearranged chromosomes, both marker and unique ones. It is concluded that introduction of a foreign oncogene into murine cell genome leads to its enhanced and progressive non-specific destabilization. Oncogen v-sis produces a more valuable karyotype destabilization than oncogen k51.     

Chromosome differentiation of spiny rats of the genus Proechimys (Rodentia, Echimyidae)]

Karyological analysis of spiny rats of the genus Proechimys revealed four chromosome forms: 2n = 30; 2n = 29; 2n = 28; 2n = 24. 30-chromosome spiny rats are characterized by unique karyotype constitution. 27-chromosome spiny rats from the territory near Iquitos differ from the same of Pucalpa (Ucayali Department) by Y-chromosome structure and banding of long arms with two pairs of autosomes. 24-chromosome rats from the regions mentioned above do not differ in G-banded chromosomes. Diploid chromosome set equal to 29, has a family originated from the parents which had 2n = 30 and 2n = 28 under the laboratory conditions. The absence of clear morphological differentiation, similarity of constituent parts of the karyotype and hybridization possibility point to relatively recent origination of the chromosome forms under study.     

Chromosome banding patterns of the aye-aye,Daubentonia madagascariensis (primates,Daubentoniidae)

The aye-aye (Daubentonia madagascariensis) is an endangered prosimian primate found only on the island of Madagascar. It is the only extant representative of its family Daubentoniidae. The phylogenetic relationship of this species with other prosimians is unclear. Because a G-banded karyotype forDaubentonia has not previously been reported, blood for preparation of lymphocyte cultures was obtained from one of the four aye-ayes in captivity in the United States. The diploid chromosome number was 30. The karyotype consisted of 14 autosomal metacentrics, 10 autosomal submetacentrics, and 4 autosomal acrocentrics. The similarities between the G-banded chromosomes ofDaubentonia and those ofPropithecus, a member of the Indriidae, support the notion thatDaubentonia has a closer relationship with the Indriidae than with other Lemuriformes or the lorisoids.     

Banded karyotypes of 20 Papionini species reveal no necessary correlation with speciation

The G-banded karyotypes of 20 species of the tribe Papionini are remarkably similar, and the amount of phylogenetic interpretation permitted is limited. The genera Mandrillus and Cercocebus may be linked by a derived chromosome 10. T. gelada may be linked to the macaques by chromosome 2. Chromosome 5, which differs in M. fascicularis, makes this species an unlikely ancestor of the Sulawesi (Celebes) macaques. An alternate hypothesis, which takes into consideration the possibility that ancestral populations may be polymorphic for these chromosome variants, suggests that different chromosome variants have become fixed in different lines. These chromosomes would therefore not reflect phylogenetic relations. In the Papionini the karyotype has not played a major role in diversification and speciation.     

Chromosomes in the flow to simplify genome analysis

Nuclear genomes of human, animals, and plants are organized into subunits called chromosomes. When isolated into aqueous suspension, mitotic chromosomes can be classified using flow cytometry according to light scatter and fluorescence parameters. Chromosomes of interest can be purified by flow sorting if they can be resolved from other chromosomes in a karyotype. The analysis and sorting are carried out at rates of 10(2)-10(4) chromosomes per second, and for complex genomes such as wheat the flow sorting technology has been ground-breaking in reducing genome complexity for genome sequencing. The high sample rate provides an attractive approach for karyotype analysis (flow karyotyping) and the purification of chromosomes in large numbers. In characterizing the chromosome complement of an organism, the high number that can be studied using flow cytometry allows for a statistically accurate analysis. Chromosome sorting plays a particularly important role in the analysis of nuclear genome structure and the analysis of particular and aberrant chromosomes. Other attractive but not well-explored features include the analysis of chromosomal proteins, chromosome ultrastructure, and high-resolution mapping using FISH. Recent results demonstrate that chromosome flow sorting can be coupled seamlessly with DNA array and next-generation sequencing technologies for high-throughput analyses. The main advantages are targeting the analysis to a genome region of interest and a significant reduction in sample complexity. As flow sorters can also sort single copies of chromosomes, shotgun sequencing DNA amplified from them enables the production of haplotype-resolved genome sequences. This review explains the principles of flow cytometric chromosome analysis and sorting (flow cytogenetics), discusses the major uses of this technology in genome analysis, and outlines future directions.     

Detection of mosaic and non-mosaic chromosome abnormalities in 6- to 8-day-old human blastocysts

A reliable technique has been developed for the production of good quality G-banded chromosome preparations from 6- to 8-day-old human blastocysts (20– 800 cell stage) from an in vitro fertilization programme. The technique involves a thymidine cell division synchronization step to reduce the exposure time to colcemid, in conjunction with a simple 70% acetic acid disaggregation procedure to produce discrete metaphases for analysis. Of 105 blastocysts processed by this technique, 9 were lost during handling and 10 showed no dividing cells. The remaining 86 produced useful separate metaphases with a mean mitotic activity of 6.5%. A full G-banded karyotype was obtained from 1–6 cells in 55 blastocysts (64%), incomplete G-banded analysis but with full information of ploidy was obtained from 18 blastocysts (21%), with 13 (15%) producing no useful cytogenetic results. Abnormalities observed included polyploidy, diploid/polyploid mosaicism, non-mosaic trisomy 16 (2 cases), 46,Xdel(X)(q21)/46,XX (1 case) and several single cells with trisomies or structural anomalies in otherwise normal blastocysts. Variable levels of structural chromosome damage, with apparent interchanges, chromosome branching and anomalous chromatid pairing were also seen. Received: 22 April 1997 / Accepted: 27 May 1997     

New insights into the karyotypic relationships of Chinese muntjac (Muntiacus reevesi), forest musk deer (Moschus berezovskii) and gayal (Bos frontalis)

To investigate the karyotypic relationships between Chinese muntjac (Muntiacus reevesi), forest musk deer (Moschus berezovskii) and gayal (Bos frontalis), a complete set of Chinese muntjac chromosome-specific painting probes has been assigned to G-banded chromosomes of these three species. Sixteen autosomal probes (i.e. 6-10, 12-22) of the Chinese muntjac each delineated one pair of conserved segments in the forest musk deer and gayal, respectively. The remaining six autosomal probes (1-5, and 11) each delineated two to five pairs of conserved segments. In total, the 22 autosomal painting probes of Chinese muntjac delineated 33 and 34 conserved chromosomal segments in the genomes of forest musk deer and gayal, respectively. The combined analysis of comparative chromosome painting and G-band comparison reveals that most interspecific homologous segments show a high degree of conservation in G-banding patterns. Eleven chromosome fissions and five chromosome fusions differentiate the karyotypes of Chinese muntjac and forest musk deer; twelve chromosome fissions and six fusions are required to convert the Chinese muntjac karyotype to that of gayal; one chromosome fission and one fusion separate the forest musk deer and gayal. The musk deer has retained a highly conserved karyotype that closely resembles the proposed ancestral pecoran karyotype but shares none of the rearrangements characteristic for the Cervidae and Bovidae. Our results substantiate that chromosomes 1-5 and 11 of Chinese muntjac originated through exclusive centromere-to-telomere fusions of ancestral acrocentric chromosomes.     

A photographic representation of the variability in the G-banded structure of the chromosomes in the mouse karyotype

Analysis of the mouse chromosomes is becoming increasingly important in many fields of genetic research. It is generally considered that the mouse chromosomes are more difficult to analyse than, for example, human chromosomes which has often led to their misidentification. This article presents a guide to the correct identification of trypsin-Giemsa banded chromosomes from the mouse. The variability in the G-banded structure of each chromosome is presented pictorially together with some suggestions for their unequivocal identification. Since many of the mouse chromosomes have similar banding patterns, those chromosomes which are more frequently misidentified have been compared and contrasted. Finally a summary of the main features for the identification of each chromosome is presented.     

2例男性育性障碍患者的联会复合体分析

运用表面铺展联会复合体（synaptonemal complex,SC）的电镜技术对2例男性育性障碍患者的联会复合体进行分析,发现患者1的部分粗线期精母细胞（20%）中出现配对紊乱（一些SCs中间未完全配对,未配对区轴心出现增粗,类似性染色体配对行为;有些SC仅两端配对,形成很短的两段SC,中间大部分未配对,在未配对区出现断裂,似乎是一个三价体和单价体）现象,大部分细胞配对正常。患者2的几乎100%生精细胞被阻断在减数分裂的前期阶段,显示联会异常如SC粉碎化、SC侧生组分膨化等现象。该文对男性育性障碍的机理进行了讨论。 Abstract:Synaptonemal complexes (SCs) of male fertility impairment were analysed in two patiants.In case one,his testicular histology was normal and there were 20% abnormal pachytene spermatoeytes,showing unsynaptic and broken SCs.It resulted in spermatogensis with unbalanced chromosomes and pregnancy wastages.In case two,he had no sperms basically.G-banded chromosome analysis of lymphocytes showed normal chromosomal karyotype,but triple fragment,lateral element swelling and fragment breakages of SCs were observed in his spermatocytes.The mechanisms of infertility,impairment of fertility for the observed men were discussed in this paper.     

Variation in the relative length of chromosomes in mammalian karyotypes. Hypothesis of equalizing selection

A hypothesis on the selective neutrality of relative lengths of karyotype chromosomes was tested. Idiograms expected based on an assumption of selective neutrality of chromosome lengths were compared with actual idiograms in more than a hundred mammalian species. The observed idiograms differed from those expected in a similar manner: in the observed idiograms, the longest chromosomes were shorter, and the shortest were longer than expected. It is suggested that karyotype chromosome variation is limited by selection against chromosome rearrangements that produce very long or very short chromosomes. An analysis of reciprocal translocations in the mouse and Drosophila showed that translocations generating chromosomes of extreme lengths were more deleterious than those generating normal-sized chromosomes. A working hypothesis was advanced stating that within-karyotype variation of chromosome lengths is accounted for by two factors: chromosome rearrangements and natural selection. Chromosome rearrangements tend to randomize relative chromosome lengths in a karyotype, whereas natural selection acts to equalize them.     

Morphological, chromosomal, and molecular evolution are uncoupled in pocket mice

C-, and G-banded chromosomes are presented for Perognathus amplus and Perognathus longimembris from Arizona, USA and Chaetodipus nelsoni from Coahuila, Mexico. The two species of Perognathus reveal similar C-band patterns, and extensive autosomal and X chromosome G-band identity with only pericentric inversions distinguishing pairs 4 and 6 and a difference in the morphology of pair 20. Three pairs of autosomal secondary constrictions were found in P. amplus and only one in P. longimembris. Only 50% of the amplus/longimembris G-banded karyotype could be aligned with that of C. nelsoni indicating extensive chromosomal restructuring has taken place since these genera last shared a common ancestor. A review of the literature suggests variable rates of morphological, chromosomal and molecular evolution in these animals.