AFLPs mark different genomic regions compared with RFLPs: a case study in tomato.

A set of three tomato chromosome 7 introgression lines (ILs) containing overlapping segments of Lycopersicon pennellii DNA was screened with a set of 10 EcoRI-MseI and 10 PstI-MseI AFLP primer combinations. A large number of markers were identified that mapped to one of the four regions of chromosome 7 defined by the set of three ILs. Because many of the identified markers have known map positions in three tomato reference maps, their location on the tomato genome could be verified. It was demonstrated that the three chromosome 7 ILs carried a chromosome 10 region harbouring a cluster of six AFLP markers that had not been detected before using RFLPs. The causes and implications of this observation are discussed.     

Screening human populations for chromosome aberrations

In order to determine the usefulness of micronuclear counts (MNC) for identifying people with relatively high frequencies of chromosome aberrations we have examined factors that influence the MNC in a learning set of blood samples obtained from 28 adults. The presence of cells with chromosome aberrations among approximately 170 metaphase cells per sample was the most important factor. Controlling for the effect of chromosome aberrations we found that age had a significant effect on MNC, but that donor sex, the mitotic index, the per cent of metaphase cells in the second or third division or the frequency of abnormal anaphase cells did not. Using logistic regression analysis we found that MNC was an excellent predictor of the presence of cells with chromosome aberrations among both the learning set and a test set of 17 additional blood samples.     

Toward a multicolor chromosome bar code for the entire human karyotype by fluorescence in situ hybridization

A colored banding pattern for human chromosomes is described that distinguishes each chromosome in a single fluorescence in situ hybridization with a set of subregional DNA probes. Alu/polymerase chain reaction products of various human/rodent somatic cell hybrids (fragment hybrids) were pooled into two probe sets that were labeled differentially and detected by red and green fluorescence. Chromosome regions hybridized by DNA present in both pools appeared yellow. The result was a multi-color set of 110 distinct signals per haploid chromosome set for the human karyotype. Each individual chromosome showed a unique sequence of signals, a result termed the “chromosome bar code”. The reproducibility of the hybridization pattern in various labeling and hybridization experiments was analyzed by computer densitometry. We have applied the chromosome bar code both in diagnostic cytogenetics and in genome studies. The approach allows the rapid identification of chromosomes and chromosome rearrangements. Although not yet showing the resolution of classical banding patterns, the present experiments demonstrate various applications in which the present multi-color bar code can significantly add to the spectrum of cytogenetic techniques. Received: 18 December 1996 / Accepted: 10 February 1997     

控制小麦种、属旗叶水分利用效率的染色体背景分析

利用ＬＣＡ－３便携式光合仪对不同染色体背景的材料测定表明,就旗叶水分利用效率（ＷＵＥ）而言,不同染色体组的上排序为ＡＡ＞ＢＢ＞ＤＤ＞ＲＲ,说明Ａ组染色体上载有控制高ＷＵＥ的基因,对中国春双端体系列的研究表明,Ａ组染色体无论在缺失长臂和短臂时,其端体也保持较高的旗叶ＷＵＥ,在１ＡＬ、２ＡＬ、２ＡＳ、７ＡＳ染色体臂上载有控制高ＷＵＥ的基因。对小黑麦附加系的研究表明,４Ｒ染色体上载有控制高ＷＵＥ的基因,     

Fertility and meiotic chromosome behaviour in autotetraploid pearl millet

Summary Tetraploidy was induced in outbred pearl millet and selection for high and low seed set was started in the C₁ generation. Segregation in the C₃ generation was observed for fertility and also for meiotic features: per cent seed set in selfed earhead, chiasma frequency, chromosome association and chromosome distribution in pollen mother cells were all affected. However, variation in seed set was observed even between samples not differing in meiotic features. It is apparent that factors regulating seed set in autotetraploid pearl millet were genic as well as chromosomal.A high frequency of univalents and trivalents was the main cause of sterility; quadrivalent misdisjunction was not a significant factor. As univalency decreased with increased chiasma formation, the gain was in the form of quadrivalents. However, individuals not differing in chiasma frequency did differ in chromosome association frequencies, indicating that the dependence of chromosome pairing behaviour on chiasmata was subject to genotypic influence.     

The use of subchromosome-length unique band sequences in the analysis of prophase chromosomes.

Using human prophase chromosome ideograms at the 850-band stage, we previously demonstrated that the 24 prophase ideograms can be divided into a set of 94 unique band sequences, each having a recognizable banding pattern distinct from other nonhomologous chromosome portions. Using actual prophase mitotic cells in this study, we analyzed the p arm of chromosome 11 and of chromosomes 16-22 and characterized a similar set of unique band sequences on actual chromosomes. This set of unique band sequences, a statistical comparison scheme, and image-processing techniques outlined in the present report can be used to identify and distinguish banding patterns of these chromosomes and to determine band pattern abnormalities.     

Vergleich der Chromosomensätze von Steinwild (Capra Ibex) und Hausziege (Capra Hircus)

Capra ibex has a diploid set of 60 chromosomes. They are all acrocentric. The Y chromosome is the only element that can be recognized individually in all mitoses. It is distinctly smaller than any autosome and its chromatids are not spread apart as is characteristic of all the other chromosomes. In these features Capra ibex and C. hircus are identical. The idiograms of the two species show that the chromosomes 18 to 21 and 41 to 44 differ, but not significantly, from each other. The Karyotypes of C. ibex and C. hircus are so alike, that the observed fertility of the hybrids does not surprise. — The amount of chromosome spiralisation does not influence the relative chromosome length. — The second longest chromosome in the haploid set of C. ibex is the X chromosome. It was taken into account that the length of the male set is shorter compared with the female set by the difference X minus Y.     

Creation of a clone panel of fox x Chinese hamster somatic cell hybrids and chromosome mapping of genes for LDHA, LDHB, GPI, ESD, G6PD, HPRT, alpha-GALA in the silver fox

A clone panel of fox-hamster somatic cell hybrids which can be used for fox gene mapping was set up. Analysis of patterns of chromosome-enzyme segregation made it possible to assign gene GPI to chromosome 1, LDHA to chromosome 11, LDHB to chromosome 8, ESD to chromosome 6 and G6PD, HPRT, alpha-GALA to chromosome X.     

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。     

Allelic interaction of F1 pollen sterility loci and abnormal chromosome behaviour caused pollen sterility in intersubspecific autotetraploid rice hybrids

The intersubspecific hybrids of autotetraploid rice has many features that increase rice yield, but lower seed set is a major hindrance in its utilization. Pollen sterility is one of the most important factors which cause intersubspecific hybrid sterility. The hybrids with greater variation in seed set were used to study how the F(1) pollen sterile loci (S-a, S-b, and S-c) interact with each other and how abnormal chromosome behaviour and allelic interaction of F(1) sterility loci affect pollen fertility and seed set of intersubspecific autotetraploid rice hybrids. The results showed that interaction between pollen sterility loci have significant effects on the pollen fertility of autotetraploid hybrids, and pollen fertility further decreased with an increase in the allelic interaction of F(1) pollen sterility loci. Abnormal ultra-structure and microtubule distribution patterns during pollen mother cell (PMC) meiosis were found in the hybrids with low pollen fertility in interphase and leptotene, suggesting that the effect-time of pollen sterility loci interaction was very early. There were highly significant differences in the number of quadrivalents and bivalents, and in chromosome configuration among all the hybrids, and quadrivalents decreased with an increase in the seed set of autotetraploid hybrids. Many different kinds of chromosomal abnormalities, such as chromosome straggling, chromosome lagging, asynchrony of chromosome disjunction, and tri-fission were found during the various developmental stages of PMC meiosis. All these abnormalities were significantly higher in sterile hybrids than in fertile hybrids, suggesting that pollen sterility gene interactions tend to increase the chromosomal abnormalities which cause the partial abortion of male gametes and leads to the decline in the seed set of the autotetraploid rice hybrids.     

白菜型油菜与蓝花子杂交的初步研究

通过胚胎培养,成功地获得了白菜型油菜（Ｂｒａｓｉｃａｃａｍｐｅｓｔｒｉｓ）与蓝花子（ＲａｐｈａｎｕｓｓａｔｉｖｕｓＬｖａｒｒａｐｈａｎｉｓｔｒｏｉｄｅｓＭａｋｉｎｏ）的属间杂种。该杂种具有两种类型;一种为大花类型,一种为小花类型。对它们进行花粉母细胞减数分裂的观察结果表明：小花类型为未加倍的杂种ＭＩ,存在１９个未配对染色体,大花类型为加倍或部分加倍杂种,加倍类型ＭＩ,１９个二价体排列在赤道板上;部分加倍类型ＡＩ,具有１０－１０－９的染色体组分割现象。大花类型具有可育性;它能够产生很多ｎ＝１９及ｎ＝９、ｎ＝１０的正常配子。染色体组分割能够产生倍半二倍体,它能用来研究染色体的功能和开展染色体工程。     

Genetics of Factors Affecting the Life History of DROSOPHILA MELANOGASTER. I. Female Productivity

Starting from four basic strains of Drosophila melanogaster, two laboratory strains (cn bw, Tokyo) and two isofemale lines (B-102, B-103) originated from a wild population in Texas, we constructed by repeated backcrosses through females for 20 or more generations a total of 16 strains of all possible combinations between the chromosome sets and cytoplasmic classes. Females from these 16 synthesized strains were then examined for their reproductive performance during their entire life span.---The chromosome set from the cn bw strain was found to associate with the highest female productivity when the age of females was very young, but these females ceased their reproduction and died relatively earlier, resulting in a smaller number of total progeny. The B-102 and B-103 chromosome sets, on the other hand, were associated with the lowest productivity when the females were young, but they lived and continued reproduction longer, resulting in a larger number of total progeny. The Tokyo chromosome set was associated with female productivity intermediate between the other two groups.---Cytoplasmic factors were found to affect the productivity of young females, with the cytoplasm from the cn bw strain associated with the highest productivity. Longevity was not cytoplasmically affected.---There was a clear interaction in female productivity between the Tokyo chromosome set and the cytoplasm from the Texas isofemale lines; the lifetime female productivity, as well as longevity, associated with the Tokyo chromosome set was found to increase considerably when it was substituted into the cytoplasm of the Texas isofemale lines. This chromosome-cytoplasm interaction appeared to be independent of the two systems of hybrid dysgenesis.     

Contrasting patterns of molecular evolution of the genes on the new and old sex chromosomes of Drosophila miranda

In organisms with chromosomal sex determination, sex is determined by a set of dimorphic sex chromosomes that are thought to have evolved from a set of originally homologous chromosomes. The chromosome inherited only through the heterogametic sex (the Y chromosome in the case of male heterogamety) often exhibits loss of genetic activity for most of the genes carried on its homolog and is hence referred to as degenerate. The process by which the proto-Y chromosome loses its genetic activity has long been the subject of much speculation. We present a DNA sequence variation analysis of marker genes on the evolving sex chromosomes (neo-sex chromosomes) of Drosophila miranda. Due to its relatively recent origin, the neo-Y chromosome of this species is presumed to be still experiencing the forces responsible for the loss of its genetic activity. Indeed, several previous studies have confirmed the presence of some active loci on this chromosome. The genes on the neo-Y chromosome surveyed in the current study show generally lower levels of variation compared with their counterparts on the neo-X chromosome or an X-linked gene. This is in accord with a reduced effective population size of the neo-Y chromosome. Interestingly, the rate of replacement nucleotide substitutions for the neo-Y linked genes is significantly higher than that for the neo-X linked genes. This is not expected under a model where the faster evolution of the X chromosome is postulated to be the main force driving the degeneration of the Y chromosome.     

加拿大披碱草和圆柱披碱草BC1植株的细胞遗传学鉴定

以加拿大披碱草(2n=4x=28)和圆柱披碱草(2n=6x=42)为材料,对其BC1植株染色体数目、配对构型以及花粉育性和结实性等进行了鉴定。结果显示:BC1代85%以上细胞染色体数目为28条(2n=4x=28);BC1植株的花粉母细胞减数分裂中期Ⅰ染色体配对行为较规则,其平均染色体构型分别为0.04Ⅰ 13.98Ⅱ,且环状二价体多于棒状二价体;BC1植株的花粉可育率和自然结实率分别为84.83%和70.98%,说明BC1植株的育性已得到恢复,为其后代优良株系的选育奠定了基础。     

Y chromosome binary markers to study the high prevalence of males in Sardinian centenarians and the genetic structure of the Sardinian population

We have analyzed a sample of 40 centenarians and 116 young controls from Sardinia, with a set of new Y chromosome binary markers, to evaluate if Y chromosome genes are involved in the high prevalence of males among centenarian Sardinians (1/2 vs. 1/4 in other populations studied). The results indicate that none of the seven lineages that account for >97% of the Y chromosome diversity in Sardinia provide an advantage with respect to the extreme longevity. However, our results, although based on the male-specific Y chromosome polymorphisms, give a clear profile of the pattern of genetic variability in Sardinia. Indeed they indicate that the Sardinian population had two main founder populations that have evolved in isolation for at least the last 5,000 years. These findings set the stage for future studies on longevity and other complex traits in Sardinia.     

The relation of exchange to nondisjunction in heterologous chromosome pairs in the Drosophila female

An analysis of the relationships in Drosophila melanogaster between one set of homologues (third chromosome) undergoing crossing over and a second, independent set (X chromosome) undergoing nondisjunction shows that the nondisjunctional set almost invariably segregates from one of the members of the crossover set and not the other. The results seem contradictory to the expectations based on the "distributive pairing hypothesis" according to which nondisjunctional (i.e., noncrossover) elements form a "distributive pool" whose members behave independently of those which have been involved in exchange.     

An extremely polymorphic locus on the short arm of the human X chromosome with homology to the long arm of the Y chromosome.

A genomic DNA clone named CRI-S232 reveals an array of highly polymorphic restriction fragments on the X chromosome as well as a set of non-polymorphic fragments on the Y chromosome. Every individual has multiple bands, highly variable in length, in every restriction enzyme digest tested. One set of bands is found in all males, and co-segregates with the Y chromosome in families. These sequences have been regionally localized by deletion mapping to the long arm of the Y chromosome. Segregation analysis in families shows that all of the remaining fragments co-segregate as a single locus on the X chromosome, each haplotype consisting of three or more polymorphic fragments. This locus (designated DXS278) is linked to several markers on Xp, the closest being dic56 (DXS143) at a distance of 2 cM. Although it is outside the pseudoautosomal region, the S232 X chromosome locus shows linkage to pseudoautosomal markers in female meiosis. In determining the X chromosome S232 haplotypes of 138 offspring among 19 families, we observed three non-parental haplotypes. Two were recombinant haplotypes, consistent with a cross-over among the S232-hybridizing fragments in maternal meiosis. The third was a mutant haplotype arising on a paternal X chromosome. The locus identified by CRI-S232 may therefore be a recombination and mutation hotspot.     

A PCR-Based Genetic Map for Human Chromosome 3

Oligonucleotide primers for 125 simple sequence repeat microsatellite-based genetic markers have been assayed by polymerase chain reaction (PCR) in the CEPH reference family panel. These microsatellites include 101 dinucleotide repeats as well as 24 new tetranucleotide repeats. The average heterozygosity of this marker set was 72.4%. Genetic data were analyzed with the genetic mapping package LINKAGE. A subset of these microsatellite markers define a set of 56 uniquely ordered loci (>1000:1 against local inversion) that span 271 cM. Sixty-seven additional loci were tightly linked to markers on the uniquely ordered map, but could not be ordered with such high precision. These markers were positioned by CMAP into confidence intervals. One hundred thirteen of the microsatellite markers were also tested on a chromosome 3 framework somatic cell hybrid panel that divides this chromosome into 23 cytogenetically defined regions, integrating the genetic and physical maps of this chromosome. The high density, high heterozygosity, and PCR format of this genetically and physically mapped set of markers will accelerate the mapping and positional cloning of new chromosome 3 genes.     

Predominant loss of hamster chromosomes in hybrids of somatic cells from the Dzungarian hamster and mice]

By means of the application of UV-inactivated Sendai virus interspecific hybrids of Dzungarian hamsterXmouse somatic cells were obtained in HAT selective medium. Karyotypic changes in these hybrid somatic cells were recorded during a 13 months' period. In the beginning each hybrid somatic cell contained 1 chromosome set of Dzungarian hamster and 1 mouse chromosome set. It was observed that throughout 13 months' of cultivation the elimination of Dzungarian hamster chromosomes prevailed over that of mouse chromosomes.     

Inheritance of plant height in hexaploid triticales with R/D substitution

Inheritance of plant height has been studied in combinations of R/D-substituted forms of hexaploid triticale and specimens that have a complete chromosome set of rye and carry various genes determining dwarfism. Analysis of F1-F3 hybrids has demonstrated an additive effect of the dwarfism genes and the genetic component of chromosome D affecting the plant height. Deviations in the segregation with respect to plant height found in F2 combinations involving R/D-substituted forms and specimens with a complete chromosomal set of the R genome may be caused by meiotic disturbances resulting from the R/D substitution and an increase frequency of the transmission of the heterologous chromosome in the monosomically substituted form.