The relation of karyotypic change to loss of contact inhibition of division in human diploid cells after SV40 infection

Following in vitro infection of human cell cultures with simian virus 40, karyotypic analyses were performed on the earliest serial culture in which cells were released from contact inhibition of division. In these cultures of diploid fibroblast-like cells, normal karyotypes were found in excess of the statistical expectation for the number of background dividing cells. Thus, loss of contact inhibition of cell division occurs prior to the alteration of chromosome morphology. These events are two of the prime alterations in the series of steps comprising transformation by this virus. The chromosomal changes which were present represent the first cytological alteration detectable. Their distribution in the human karyotype was examined, but was found to have no relation to any specific chromosome or chromosome group.     

Chromosome numbers in plant cytotaxonomy: concepts and implications

Chromosome number is the karyotype feature most commonly used in cytotaxonomical analyses. The chromosome number can be a plesiomorphic characteristic of a large clade or a recurrent trait which arose independently in two or more clades. Some concepts regarding chromosome number variation, such as base number, aneuploidy, paleopolyploidy, and neopolyploidy have been used by different authors in quite different ways. Therefore, its use in cytotaxonomy and karyotype evolution deserves much attention. In this paper, these terms are reappraised and their meaning and implication for plant cytotaxonomy are discussed.     

The evolutionary origin of a novel karyotype in Timarcha (Coleoptera, Chrysomelidae) and general trends of chromosome evolution in the genus

In this work, we have analysed the karyotypes of six species of Timarcha for the first time and updated the cytological information for two additional taxa, for one of them confirming previous results ( Timarcha erosa vermiculata ), but not for the other ( T. scabripennis ). We describe the remarkable karyotype of T. aurichalcea , the lowest chromosome number in the genus (2 n  = 18), distinctive as well for the presence of an unusual chiasmatic sexual bivalent hitherto unreported for Timarcha . This study increases the number of species studied cytologically in this genus to forty. Additional cytogenetic analyses are performed on several species, including Ag-NOR staining and fluorescent in situ hybridization (FISH) studies with ribosomal DNA probes. Karyotype evolution is analysed by tracing different karyotype coding strategies on a published independent phylogenetic hypothesis for Timarcha based on the study of three genetic markers. The implementation of a likelihood model of character change optimized onto the phylogeny is tentatively used to detect possible drifts in chromosome changes. These analyses show that karyotype is conservative in the evolution of the genus and that there is an apparent trend to reducing chromosome number. Cytological and phylogenetic data are used to explain the evolutionary origin of the karyotype of T. aurichalcea by two centric fusions involving one pair of acrocentric autosomes and the sexual chromosomes.     

Chromosomal instability in near-diploid colorectal cancer: a link between numbers and structure

Chromosomal instability (CIN) plays a crucial role in tumor development and occurs mainly as the consequence of either missegregation of normal chromosomes (MSG) or structural rearrangement (SR). However, little is known about the respective chromosomal targets of MSG and SR and the way these processes combined within tumors to generate CIN. To address these questions, we karyotyped a consecutive series of 96 near-diploid colorectal cancers (CRCs) and distinguished chromosomal changes generated by either MSG or SR in tumor cells. Eighty-three tumors (86%) presented with chromosomal abnormalities that contained both MSGs and SRs to varying degrees whereas all 13 others (14%) showed normal karyotype. Using a maximum likelihood statistical method, chromosomes affected by MSG or SR and likely to represent changes that are selected for during tumor progression were found to be different and mostly mutually exclusive. MSGs and SRs were not randomly associated within tumors, delineating two major pathways of chromosome alterations that consisted of either chromosome gains by MSG or chromosomal losses by both MSG and SR. CRCs showing microsatellite instability (MSI) presented with either normal karyotype or chromosome gains whereas MSS (microsatellite stable) CRCs exhibited a combination of the two pathways. Taken together, these data provide new insights into the respective involvement of MSG and SR in near-diploid colorectal cancers, showing how these processes target distinct portions of the genome and result in specific patterns of chromosomal changes according to MSI status.     

Prenatally identified case of mosaicism of chromosome 16 trisomy

We present the prenatally identified case of mosaicism of chromosome 16 trisomy. A patient with the pregnancy complicated in the first trimester by the threat of breaking was refered to the high risk group according to the results of the screening program. The ultrasonic research revealed a number of phenotypical pathologies in 19-weeks-old fetus such as congenital heart disease (ventricular septal defect), hyperechoic bowel, single umbilical artery and some other ones. Cytogenetical and FISH analyses of the placental villi revealed karyotype with chromosome 16 trisomy. The further research of amniotic fluid cells revealed the karyotype of fetus as mos47,XX,+16 / 46,XX. The pathologoanatomic research of the abortus has verified the multiple congenital malformations.     

Re-evaluation of HeLa, HeLa S3, and HEp-2 karyotypes

In contrast to earlier reports, this study on HeLa, HeLa S3, and HEp-2 revealed that karyotypes of each cell line are characterized by a consistent marker chromosome composition and a constant number of copies for both normal and marker chromosomes. Based on these chromosome fingerprints and an analysis of 50 metaphases, the modal karyotype of each cell line was defined. Each modal karyotype had the composite content of the previously reported karyotypes of the same cell line, and, generally, the former had the same or a higher number of copies per chromosome than the latter. This modal karyotype can be used as a standard to identify and further individualize both the cell line itself and a subline within that cell line. We have also found that many cells within each cell line have the same karyotype. Portions of numerical data are compiled in a chart format by which the extent of chromosome differences between cultures can readily be compared. Also discussed in brief are characteristic chromosome changes that may help distinguish clonally derived cell lines from lines derived by cross-contamination.     

基于比较核型分析方法追溯百合族 (百合科) 二型性核型的起源

百合族具有非常一致的二型性核型,由4条长染色体以及20条短染色体组成。目前有两个假说解释其二型性核型的来源,着丝粒横裂和多倍化。但是,具体是哪一种机制起主要作用仍然不清楚。根据文献以及自己的实验结果,我们整理并重新分析了百合亚科和美德兰亚科所有属的核型资料。比较核型分析结果表明,来自单条染色体的特征、染色体臂数、核型不对称性以及染色体的相对长度诸方面的证据都支持着丝粒横列是百合族核型进化的主要机制,但不能排除其它的机制也在起着作用,如臂间倒位和易位。臂间倒位和易位可能在郁金香族的核型进化中起着主要的作用。另外,本研究还报道了三个种的核型,粗茎贝母 (Fritillaria crassicaulis)、准格尔郁金香 (Tulipa suaveolens) 和尖果洼瓣花 (Gagea oxycarpa)。     

Studies on Image Automated Analysis and Recognition of Plant Chromosome

A plant chromosome image analysis CHROM. HUK software system has been developed in the light of the theory of image analysis and recognition and applied in karyotype automated analysis of Xizang wild barley (Hordeum agriocrithon Aberg var. nigrum) and Cupressus gigantea Cheng et L. K. Fu. The main features of automated analysis include the pre-processing of chromosome image, determinating peak-valley threshold of chromosome, separation of overlapping chromosome, evaluation of centre line of chromosome,limit erotion recognition of position of centromere and second constric, extraction of characterictic parameters of chromosome and karyotype analysis. The vast amount of data obtained could be stored, operated and used for further statistical analysis. According to the estimation in the 95% confidence interval and the tree type sort, the chromosome were paired and sorted. In the meantime, a karyogram and an idiogram of karyotype were generated automatically through computerization.     

多花水仙(Narcissus tozetta L.)染色体基数x=10和X=11之间进化关系的研究

多花水仙的染色体基数有x=10和x=11两类。基数x=10组型有两种,一种是具6长、4短的典型不对称的二形染色体组型;另一种是具有4长、2中、4短(或5长、2中、3短)的非二形染色体组型。基数x=11则具有4长、2中、5短(或5长、2中、4短)的非二型或非典型二形的染色体组型。x=10的典型不对称的二形染色体组型是原始的组型。基数x=11是从原始的x=10、2n=20组型中的(第5、6号)染色体发生不等长易位后,增加了一对短小的中着丝粒染色体而形成的。另一个x=10、2n=20的非二型新组型,可能从x=11组型丢失了短小的中着丝粒染色体衍生而来,也可能从易位后的个体所产生的不含中着丝粒染色体的雌、雄n配子结合而得到。     

染色体多态性与临床效应及生殖关系的探究

为了探讨人类染色体结构多态性与生殖异常临床效应的关系,按常规技术方法制备外周血淋巴细胞染色体,经G、C显带,对1 414例遗传咨询者进行核型分析,检出异常核型273例。其中多态性变异180例,占65.93%,非多态性异常核型93例,占34.07％。多态性变异包括D、G组短臂增长10例,次缢痕增长(包括1、9和16号染色体)35例,大Y染色体和小Y染色体 99例,Y染色体臂间倒位6例,9号染色体臂间倒位30例。结果表明,人类染色体多态性与流产、不孕不育、死胎、生育畸形儿等有相关性。     

Meiotic drive shapes rates of karyotype evolution in mammals

Chromosome number is perhaps the most basic characteristic of a genome, yet generalizations that can explain the evolution of this trait across large clades have remained elusive. Using karyotype data from over 1000 mammals, we developed and applied a phylogenetic model of chromosome evolution that links chromosome number changes with karyotype morphology. Using our model, we infer that rates of chromosome number evolution are significantly lower in species with karyotypes that consist of either all bibrachial or all monobrachial chromosomes than in species with a mix of both types of morphologies. We suggest that species with homogeneous karyotypes may represent cases where meiotic drive acts to stabilize the karyotype, favoring the chromosome morphologies already present in the genome. In contrast, rapid bouts of chromosome number evolution in taxa with mixed karyotypes may indicate that a switch in the polarity of female meiotic drive favors changes in chromosome number. We do not find any evidence that karyotype morphology affects rates of speciation or extinction. Furthermore, we document that switches in meiotic drive polarity are likely common and have occurred in most major clades of mammals, and that rapid remodeling of karyotypes may be more common than once thought.     

西藏巨柏核型的图象自动分析与识别的研究

我们应用图象自动分析和识别的原理和方法,建立了植物染色体自动分析CHROMHUK软件系统,并首次对西藏巨柏进行了核型自动分析,抽取了染色体多个特征多数:相对长度、臂比、着丝点指数、相对体密度和次缢痕相对长度.对247个巨柏体细胞进行多参数数据统计和分析,并设置95°.置信判别区域和树分类判别.实现了染色体自动配对和分类,并由计算机直接输出染色体的组型图和核型模式图.分析结果表明:巨柏体细胞的染色体数目为2n=22,按Levan的分类标准,其核型公式为2n=4m(SC)+16m+2sm.据Stabbins分类为1A型.     

Owl monkey gene mapping: the assignment of gene loci for catalase, beta-globin gene cluster, HRAS1, insulin, and parathyroid hormone

Using somatic cell genetics and Southern blot hybridization, we have mapped five structural genes in the owl monkey, coding for catalase (CAT), the beta-globin gene cluster (HBBC), c-Ha-ras 1 (HRAS1), insulin (INS), and parathyroid hormone (PTH). All five loci are mapped to chromosome 19 of karyotype VI (2n = 49,50) of the owl monkey; CAT, HBBC, INS, and PTH can be assigned to chromosome 4 of karyotype V (2n = 46), while CAT and HBBC can be assigned to chromosome 2 of karyotype III (2n = 53). Using in situ hybridization, the CAT gene was precisely mapped on the mid-region and the beta-globin gene cluster on the telomeric end of chromosome 2q(K-III). Our results provide significant insight into the evolutionary history of these gene loci. While these loci are separated into at least two major segments in rodents such as the mouse, our results suggest conservation of a single chromosome arm among higher primates.     

A Study on Karyotypes of the Genus Lycoris

The genus Lycoris (Amaryllidaceae) consists of about 20 species, all of which are confined to temperate China, Japan and Korea. Cytological investigations, including a reexamination of the karyotypes of 14 taxa, measurements of relative nuclear DNA content, and meiotic configuration observations on some specific forms and interspecific hybrids, have been carried out by the present authors in order to re-evaluate the mode of karyotype evolution and the role of hybridization in the speciation of Lycoris. These have resulted in a new theory for explaining the karyotype evolution in the genus, which will be considered elsewhere. The present paper deals with observations on karyotypes of 11 species, 1 variety and 2 artificial hybrids. Results obtained through karyotype analysis, as shown by the data in Table 1, Plates I-VI and Figs. 1-2, reveal that: (1) the karyotypes of Lycoris rosea, L. radiata var. pumila, L. sprengeri, L. haywardii, L. caldwellii, L. squamigera and L. radiata are, on the whole, consistent with those reported by the previous authors^{[1,2,3,4,5,8,10,12]};(2) the I (rodshaped) chromosomes of L. chinensis and L. longituba are all T’s (telocentric) instead of t’s (acrocentric) or t(Sat)’s; (3) the three materials of L. aurea of different sources have shown a karyotypic differentiation: one with 2n=14=8m+6T, and the others with 2n=16=6m+10T: (4) both of the karyotypes of L. straminea and L. albiflora are 2n=19=3V+6I, inconsistent with 2n=16=6V+10I for the former and with 2n=17=5V+12I for the latter as reported by Inariyama (1953), Bose and Flory (1963) and Kurita (1987). The following aspects are worthwhile discussing: 1. The types of chromosomes. Karyotype analyses reveal the existence of three major chromosome types in Lycoris: (1) m (metacentric) chromosomes: (2) t (acrocentric) chromosomes, with short arms, (3) T (telocentric) chromosomes, sometimes with dot-like terminal centromeres. To distinghish t’s from T’s is of paramount importance for solving the problem of karyotype evolution in Lycoris. Bose (1963) pointed out that in the species with 2n=22, all I chromosomes were t’s, while in species with 2n=12-16, all I chromosomes were T’s. Our results of chromosome observations are consistent with Bose’s remarks. Some authorst^[3,6] have probably mistaken the dot-like terminal centromeres of T’s of L. longituba and L. chinensis as the short arms of t’s. 2. The significance of Robertsonian change in karyotype evolution. Although chromosome numbers and karyotypes are very variable in Lycoris, as shown in Table 1, the total number of arms of a chromosome complement of any species is always multiples of 11. Hence, it seems likely that Robertsonian changes have taken part in karyotype alteration, The genus has a series of basic chromosome numbers: 6, 7, 8 and 11. But which is the most primitive one? It is uncertain whether a successive decrease in chromosome numbers as a result of Robertsonian fusion or a gradual increase in chromosome numbers brought about by fission (fragmentation) has been the essential mechanism for karyotype evolution and speciation in Lycoris. These problems are of crucial importance and will be discussed in our subsequent papers. 3. The origin of polyploids. As evident from Table 1, there are two levels of ploidy differentiation in Lycoris: (1) di ploids with 2n=22 or the equivalent of 22, (2) triploids with 2n=33 or the equivalent of 33. The most common way of origination of triploids in plants is the hybridization of diploids with Tetraploids. But tetraploids have never been found in Lycoris. Thus, it is suggested that the triploids have originated from the combination of an unreduced gamete of a diploid with a normal gamete of another diploid. 4. The role of hybridization in speciation. Results of karyotype analyses show that hybridization has taken an important part in the speciation of Lycoris. Two types of hybrids have been found: (1) 2n=19= 3V+ 16I, L. straminea, L. albiflora and the two artificial hybrids L. sprengeri×L. chinensis and L. haywardii× L. chinensis all possess this karyotype. It could be seen from the above chromosome number and karyotype that this sort of karyotype is exactly half of the total sum of 2n=22I and 2n=16= 6V+10I. It is, therefore, quite evident that taxa possessing this karyotype are all diploid hybrids of 2n=22 and 2n=16, (2) 2n=27=6V+21I, L. caldwellii and L. squamigera possess this karyotype. It is reasonable to assume, too, that they are segmental allotriploids and have arisen from the combination of an unreduced diploid gamete of 2n=16 and a normal haploid gamete of 2n=22. The origin of the hybrid karyotype 2n=17=5V+12I reported by Inari- yama (1953) is similar to that of 2n=19, except that one of the parents possesses 2n=12= 10V+2I instead of 2n=16=6V+10I. The origin of the other hybrid karyotype 2n=30=3V+ 27I reported by Bose (1963) is similar to that of 2n=27, but the diploid gamete comes from taxa possessing 2n=22 instead of 2n=16.     

江豚的染色体核型研究

江豚(Neophocaena phocaenoides)是鲸目(Cetacea)鼠海豚科(Phocaenidae)的一种小型齿鲸,在淡水和海洋中均有分布。关于江豚染色体的研究,国外文献中尚未见记载,国内亦无报道。Pilleri和Gihr(1972,1975)根据江豚的形态解剖学的研究,认为我国产的江豚和印度洋的及日本海的江豚不属同一个种,但国际上对此尚有不同意见。因此,搞清江豚染色体的核型,将可有助于澄清江豚属的的分类问题。本文就我国长江产江豚的染色体核型作初步探讨。     

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.     

Stabilization of a terminal inversion duplication of 8p by telomere capture from 18q

Terminal inversion duplications of the short arm of chromosome 8 are one of the more common chromosome rearrangements in humans. We report an infant with multiple congenital anomalies, in whom karyotype analysis showed a terminal inversion duplication of 8p including additional material at the distal end of the derivative chromosome, shown to be of chromosome 18q origin. Terminal inversion duplications of 8p are the result of meiotic recombination between inverted olfactory gene receptor repeats in 8p. This recombination generates a dicentric intermediate that breaks during anaphase, and the broken chromosome end is stabilized by telomere healing or telomere capture. The origin of the telomeric region in the majority of constitutional chromosome deletions studied to date was shown to be from telomere healing; the de novo addition of telomeric repeats. In the proband a cytogenetically detectable piece of chromosome 18q was present on the distal end of the derivative 8, suggesting that this chromosome was stabilized by telomere capture of 18q. FISH analyses of additional cases may yield information as to whether telomere capture or telomere-healing events are the predominant mechanism of chromosome stabilization in terminal inversion duplications of 8p.     

Structural karyotypic variability and polyploidy in natural populations of the South American <Emphasis Type="Italic">Lathyrus nervosus</Emphasis> Lam. (Fabaceae)

Knowledge of the chromosome variation in wild populations is essential to understand the pathways and restrictions of karyotype evolution in plants. The aim of this study is to conduct an intraspecific analysis of the karyotypes by fluorochrome banding and ribosomal DNA (rDNA) loci detection by fluorescent in situ hybridization (FISH) and of the meiotic behaviour in natural populations of Lathyrus nervosus, sect. Notolathyrus. Chromosome banding showed that, despite the high constancy in the karyotype formula and in the rDNA loci among populations, there is intraspecific variation in the amount and distribution pattern of 4’,6-diamidino-2-phenylindole (DAPI⁺) heterochromatin. However, those changes were not related to the total chromosome length of the haploid complements. This fact demonstrates that structural chromosome changes may be one of the most important mechanisms for karyotype variation among natural populations of L. nervosus. The chromosome number surveyed at the population level revealed the first case of polyploidy in South American species and the first case of uneven polyploidy of the genus. All the chromosome markers analysed indicated that the polyploids found originated by autopolyploidy. The meiotic analysis showed different chromosome abnormalities that may be generating numerical and structural changes in the sporads. The finding of unreduced gametes that are alive at anthesis suggests sexual polyploidization as the most probable mechanism involved in the origin of these 3x and 4x autopolyploid cytotypes in L. nervosus.     

Cytogenetic aspects of phylogeny in the Bovidae. I. G-banding

An extensive G-banding study of karyotypes of 12 species of Bovidae has been undertaken in an attempt to trace homologies and patterns of evolution of karyotype phenotypes throughout the family. G-banding profiles revealed a considerable degree of chromosome-arm homology throughout the group, which also extended into the related superfamilies, the Giraffoidea and Cervoidea. The conservation of banding patterns in chromosome arms strongly indicates that Robertsonian translocation type rearrangements have provided the major source of interspecies karyotype differences, with inversions and reciprocal and tandem translocations providing relatively minor contributions. Examples of individuals carrying newly arisen Robertsonian translocations are not infrequent, and in one instance there was evidence that two similar rearrangements had arisen independently in two species. Despite the extensive changes in karyotype organization, subfamilies within the Bovidae were characterized by the presence of common rearrangements, and those involving autosomal pairs 11 and 12 of the ox, as well as the X chromosome, separate the Bovinae from the Caprinae and Hippotraginae.