The spontaneous aneuploidy of the embryonic fibroblasts in C3H/He and CBA/Ca mouse strains occurring during their neoplastic evolution]

Karyological analysis of 6 cell lines with distinct tumorigenic properties of mouse strains C3H/He and CBA/Ca has been carried out using differential chromosome staining. All the cell lines are characterized by a decreased number of copies of normal chromosome 7, the increased number of normal copies of chromosome 10 being specific of the cell lines with intermediate tumorigenicity. Cell lines with maximum tumorigenicity differed from all other lines by the increased number of copies of chromosome 5 and by the decreased number of copies of chromosome 6. A wide independent variability was observed in the number of chromosomes and of several types of abnormal chromosomes throughout the neoplastic evolution of cells, to begin from the early immortal passages. But the proportion of normal chromosomes per cell in the studied lines revealed relatively stable values. The potential phenotypical heterogenicity of the lines with maximum tumorigenicity, expressed in their clonal progeny, was associated with the instability in the number of chromosome 15 copies in cells of these lines. It is concluded that multiple genetic events are required in the spontaneous neoplastic evolution of fibroblasts, and only specific traits of the karyotypic instability, associated with the variability of the number of copies of specific chromosomes, may constitute the genetic basis for the above process.     

Spontaneous and induced chromosome aberrations in the bone marrow cells of different strains of mice during aging

Sensitivity of bone marrow cell chromosomes to alkylating agent thiophosphamide and to gamma-irradiation has been studied in the course of ageing in 101/H, A/He, CBA, BALB/c and C57BL/6 mice. The effects of both the kinds of mutagenic treatment and of the genotype of the animals on the age-dependent changes in sensitivity of bone marrow cell chromosomes were found. Following gamma-irradiation under our experimental conditions, no variation in the output of chromosomal aberrations was observed between the strains studied. Following thiophosphamide treatment, aged mice of strains 101/H, A/He and CBA showed an increased chromosome instability as compared to young ones. In C57BL/6 mice the level of induced chromosome aberrations was found to be age-independent. Following thiophosphamide treatment, cells with multiple chromosome lesions were found in the bone marrow. The higher instability of aged animals in some strains was mainly due to a sharp increase in the number of such cells. In the intact mice of all the strains studied no age-dependent increase in the number of cells showing structural chromosome aberrations was observed, while accumulation of aneuploid cells varied with genotype.     

Apoptosis in the preimplantation mouse embryo: effect of strain difference and in vitro culture.

Cell death by apoptosis occurs predominantly in the inner cell mass (ICM) of the blastocyst, the cell population which carries the germ line and gives rise to the foetus. The frequency of apoptosis in blastocysts varies widely within outbred species such as human and cow. We have addressed the basis of this variation by examining the relative influence of strain difference and in vitro culture conditions on apoptosis, using embryos from two different strains of mice (MF1 and C57BL6/CBA) in two different culture media (M16 and kSOM). In both strains and all crosses apoptosis was first detected by nuclear fragmentation or TUNEL [Terminal deoxynucleotidyl transferase mediated d-UTP nick end-labelling] labelling at the early blastocyst stage. This was true for embryos which had developed in vivo, and in vitro in both M16 and kSOM. The apoptotic index in blastocysts was found to be significantly different between both media and strain (P < 0.0001). Blastocysts from MF1 x MF1 at equivalent stages had an apoptotic index of 32.4% in M16 and 20.3% in kSOM. Blastocysts from C57BL6/CBA x C57BL6/CBA had an apoptotic index of 19.3% in M16 and 14.4% in kSOM. When embryos of similar cell number were compared, a significantly greater apoptotic index was found for cultured MF1 x MF1 embryos with a cell number between 40 and 59 compared to similar directly flushed C57BL6/CBA embryos (P = 0.001), and MF1 embryos (P < 0.0005). MF1 x MF1 embryos and C57BL6/CBA x MF1 embryos of 60-79 cells had a greater apoptotic index in M16 than kSOM (P < 0.0005) but the difference between media was not significant for C57BL6/CBA x C57BL6/CBA. When strain was compared MF1 x MF1 embryos of 60-79 cells had a significantly greater apoptotic index than C57BL6/CBA x MF1 in both media (P < 0.0005 M16; P = 0.002 kSOM) and than C57BL6/CBA x C57BL6/CBA in M16 (P = 0.019). Our data suggest that genetic make-up and the chemical composition of simple medium are equally important in determining the level of apoptosis.     

Mapping of PRM1 to human chromosome 16 and tight linkage of Prm-1 and Prm-2 on mouse chromosome 16

The protamines are small, arginine-rich nuclear proteins that replace histones and transition proteins late in the haploid phase of spermatogenesis in mammals. The two mouse genes encoding protamines--Prm-1 and Prm-2--have been molecularly cloned and mapped to mouse chromosome 16 (MMU 16). A cDNA clone of mouse Prm-1 that hybridized to the corresponding human gene was used to analyze a panel of somatic cell hybrids made between human lymphoblasts and the E36 hamster cell line. The human gene, which we have designated PRM 1, was syntenic with human chromosome 16 (HSA 16) and discordant with all other human chromosomes. Linkage analysis in the mouse was accomplished using the backcross (Czech II x BALB/c Pt) x Czech II to map Prm-1 and Prm-2 to a position near the 5' terminus of MMU 16. No recombination between Prm-1 and Prm-2 was observed among 89 progeny of the Czech II x BALB/c cross or among 94 progeny of the backcross (CBA/J x BALB/cJ) x BALB/cJ, demonstrating that the two loci are separated by less than 1.6 cM on MMU 16. This tight linkage may be of functional significance, as Prm-1 and Prm-2 are among a limited number of genes known to be expressed postmeiotically in male haploid germ cells.     

The development of diploid parthenogenetic mouse embryos of the inbred C57BL and CBA strains]

We studied preimplantation development in vitro and postimplantation development in vivo of diploid parthenogenetic mouse embryos of C57BL/6 and CBA strains, as well as of (CBA x C57BL/6)F1 hybrids. Development to blastocyst stage of diploid eggs obtained from C57BL/6, CBA, and hybrid mice was observed in 90, 15, and 73% cases, respectively. After implantation, C57BL/6 embryos did not develop to somite stages, while CBA and hybrid embryos reached various stages of somite formation in 45 and 30% cases, respectively. Cultivation of embryos beginning from one-cell stage in the medium containing 2% newborn calf serum increased the yield of blastocysts from 15 to 59% in CBA embryos and from 73 to 90% in hybrids; However, such effect was not observed with C57BL/6 embryos. The latest stages of development observed in CBA and hybrid diploid parthenogenetic embryos were 33-35 somites and 25-30 somites, respectively. Imprinting patterns in chromosomes of CBA and C57BL/6 gametes are discussed.     

Segregational fidelity of chromosomes in human thyroid tumour cells

Using fluorescence in situ hybridisation (FISH) we have analysed the segregational fidelity of all the human chromosomes during mitotic cell division. The losses and gains of chromosomes were analysed in human polyploid cell lines derived from a well-differentiated papillary thyroid cancer. These thyroid cells can be cultured for more than 300 population doublings. For the purpose of our study the polyploid nature of the cells may act as a protective buffer against the cell-lethal effects of the loss of individual chromosomes. To evaluate the role of the p53 gene product in maintaining the fidelity of chromosome segregation we compared the frequencies of chromosome loss and gain in cultures with wild-type p53 activity (K1E7neo3) and cultures transfected with plasmids expressing a mutant p53 product (K1E7scx6). Cultures were analysed for the presence of both structurally normal and rearranged chromosomes at both early and late passages. Cell cultures with defective p53 activity showed progressive chromosome loss from a median chromosome number of 87–97 to 75–86. Cell growth in cultures with wild-type p53 activity showed the loss of chromosomes 6, 7, and 8 and the gain of 17 and 20. Cultures expressing mutant p53 activity showed the loss of chromosomes 2, 5, 14 and 17 and the gain of 4 and 22. The combination of defective p53 and growth resulted in further destabilisation with the additional losses of chromosomes 3, 11, 15, 16 and 21. Chromosomes 1, 9, 10, 12, 13, 18, 19, X and Y segregated stably under all the culture conditions as did the structurally rearranged marker chromosomes. The study has demonstrated variation in the fidelity of mitotic chromosome segregation and the influence of p53 gene activity upon the segregation of individual human chromosomes. Received: 7 August 1998; in revised form: 28 August 1998 / Accepted: 29 August 1998     

Physical mapping of three fruit ripening genes：Endopolygalacturonase,ACC oxidase and ACC synthase from apple（Malus x domestica） in an apple rootstock A106（Malus sieboldii

The apple rootstock,A106(Malus sieboldii),had 17 bivalents in pollen mother cells at meiotic metaphase 1,and 17 chromosomes in a haploid pollen cell.Karyotypes were prepared from root-tip cells with 2n=34 chromosomes,Seven out of 82 karyotypes(8.5%) showed one pari of satellites at the end of the short arm of chromosome 3.C-bands were shown on 6 pairs of chromosomes 2,4,6,8,14,and 16 near the telomeric regions of short arms.Probes for three ripening-related genes from Malus x domestica:endopolygalacturonase(EPG,0.6kb),ACC oxidase(1.2kb),and ACC synthase(2kb)were hybridized in situ to metaphase chromosomes of A106.Hybridization sites for the EPG gene were observed on the long arm of chromosome 14 in 15 out of 16 replicate spreads and proximal to the centromere of chromosomes 6 and 11.For the ACC oxidase gene,hylridization sites were observed in the telomeric region of the short arm of chromosomes 5 and 11 in 87% and 81% of 16 spreads respectively,proxiaml to the centromere of chromosome 1 in 81% of the spreads,and on the long arm of chromosome 13 in 50% of the spreads. Physical mapping of three fruit ripening genes in an apple rootstock A106.Twenty five spreads were studied for the ACC synthase gene and hybridization sites were observed in the telomeric region of the short arm of chromosome 12 in 96% of the spreads.chromosomes 9 and 10 in 76% of the spreads,and chromosome 17 in 56% of the spreads.     

Relationship between T- and B-lymphocyte cooperation and their syngeneity]

Cooperation efficiency of (CBA x C57BL/6) F1 thymocytes and CBA bone marrow cells in immune response to SRBC was compared with the syngenic combination of the same cells. Selectivity of interaction of the T- and B-lymphocytes of different origin was studied in incomplete cyclophosphamines (CBA x C57BL/6) leads to CBA chimerae, where donors were primed with SRBC and the recipients were either intact or tolerant to the given antigen. F1 T-cells proved to interact with the CAB-B-cells 10-15 times less effectively than with the syngenic B-cells. It is suggested that similarity between the antigenic structure of the cell membrane of the T- and B-lymphocytes, aiding their physical contact, increased the action efficiency of the T-mediator on the B-cell.     

Alteration of chromosome behavior and synchronization of parental chromosomes after successive generations in Brassica napus x Orychophragmus violaceus hybrids.

In an earlier study, the progenies of intergeneric hybrids Brassica napus (2n = 38) x Orychophragmus violaceus (2n = 24) were investigated in successive generations (F1-F4) for the cytological phenomenon of parental genome separation during mitotic and meiotic division. In the present study, inbred lines (F5-F8) derived from 1 such hybrid were characterized for morphology, chromosome pairing behaviour, and genome composition. One F5 plant (2n = 31) with slightly yellow petals and 12:19 and 15:16 segregation ratios in its pollen mother cells (PMCs) produced F6 plants with distinct morphological characteristics and wide variations in fertility and chromosome numbers (2n = 25-38). F7 and F8 lines with distinctive morphology and wide ranges in chromsome numbers were established. In PMCs of F7 plants from 4 F6 plants, 0-12 labelled chromosomes from O. violaceus, which predominantly appeared as bivalents, were identified by genomic in situ hybridization. They behaved synchronously with B. napus chromosomes during meiotic division. The results provide molecular cytogenetic evidence of the inclusion of O. violaceus chromosomes in the original hybrids and the cytology in the hybrids documented earlier. They also show that chromosome behaviour was altered and the parental chromosomes became synchronized after successive generations.     

Chromosomal rearrangements and their effects in spontaneous immortalization and transformation of rat embryo cells in vitro

G-banding analysis of LRec-1 and LRec-3, spontaneously immortalized cell lines from rat embryo fibroblast, revealed diploid karyotypes with specific clonal structural rearrangements of chromosomes 7 and 19 - del(7)(q11.2q22.1), t(7;19)(q11.1;q12) in malignant stage. Both clonal abnormalities of chromosomes 7 and 19 were also revealed in LRec-1k clone and LRec-1 sf cell line. Previous study of LRec-1 and LRec-3 cells showed the presence of karyotypes with pseudodiploid modal chromosome number, partial trisomy of chromosome 7 and same clonal structural rearrangements of chromosomes 7 and 19 in immortalized stage. In malignant stage, the trisomy 6 and new clonal structural rearrangements of chromosomes 1, 2, 11, 15, 18, 19 and of chromosomes 10, 20 were also found in LRec-1 sf and LRec-1 cells, accordingly. There were no new clonal structural chromosome rearrangements in LRec-1 k and LRec-3 cells. We compared locies of chromosomes involved in rearrangements with mapped genes on these chromosomes according to RATMAP. Supposedly these genes are involved in spontaneous immortalization of rat embryo fibroblast and malignant transformation of LRec-1 and LRec-3 cells and rearrangements of chromosomes 1, 2, 11, 15 and 18 facilitate expression of growth factors of LRec-1 sf cells.     

The CBA mouse as a model for age-related aneuploidy in man: studies of oocyte maturation,spindle formation and chromosome alignment during meiosis

To elucidate the possible mechanism of disturbances in chromosome segregation leading to the increase in aneuploidy in oocytes of aged females we examined the meiotic spindles of CBA/Ca mice. Employing immunofluorescence with an anti-tubulin antibody, and human scleroderma serum, as well as 4-6-diamidino-2-phenylindole (DAPI) staining of chromosomes the microtubular cytoskeleton could be visualized, and the behaviour of chromosomes and centromeres of oocytes spontaneously maturing in vitro could be studied. The morphology of spindles during the first meiotic division was not conspiciously different in oocytes from young and aged mice as far as the cytoskeletal elements were concerned. Neither multipolar spindles nor pronounced cytoplasmic asters appeared in oocytes of mice approaching the end of their reproductive life (9 months and older). Oocytes of aged females also did not exhibit any sign of premature separation of parental chromosomes at prophase, obvious malorientations of bivalents, or significant lagging of chromosomes during ana and telophase. Metaphase I with all bivalents aligned at the spindle equator appeared to be a relatively brief stage in oocyte development compared with pro-and prometaphase. Therefore, already slight disturbances occuring in the timing of the developmental programme which leads to a premature anaphase transition may be responsible for the high incidence of chromosomally unbalanced gametes in aged females, rather than non-separation and lagging of chromosomes during late ana-and telophase. In a second set of experiments we compared the metaphase II spindles of spontaneously ovulated oocytes obtained from animals at different ages. Previous studies have shown that spindle length and chromosome alignment may be altered in cells predisposed to aneuploidy. To distinguish between the significance of the chronological age of the female and the physiological age of the ovaries (as indicated by the total number of oocytes remaining) we examined the spindle apparatus in young (3–4 months old) and aged (9 months and older) mice as well as CBA females which had been unilaterally ovariectomized (uni-ovx) early in adult life and were approaching the end of their reproductive life at 6–7 months of age. Measurements of the pole-to-pole distance implied that spindle length may be related to maternal age. In oocytes of aged (9 month), uni-ovx (6 month) as well as 6-month-old sham-operated controls the metaphase II spindle was significantly shorter than in oocytes of young mice. By contrast, chromosome disorder and displacement was most pronounced in the aged and uni-ovx mice whilst most oocytes from young mice and moderately aged shamtreated controls exhibited a more regular alignment of chromosomes. These results, which are consistent with recent findings in CBA mice of an increased rate of aneuploidy in females approaching the end of their reproductive life, are discussed with respect to the hypothesis that the aetiology of aneuploidy rests on the critical timing of different events in oocyte development.     

Organization of early and late replicating DNA in human chromosome territories

It has been suggested that DNA organized into replication foci during S-phase remains stably aggregated in non-S-phase cells and that these stable aggregates provide fundamental units of nuclear or chromosome architecture [C. Meng and R. Berezney (1991) J. Cell Biol. 115, 95a; E. Sparvoli et al. (1994) J. Cell Sci. 107, 3097-3103; D. A. Jackson and A. Pombo (1998) J. Cell Biol. 140, 1285-1295; D. Zink et al. (1998) Hum. Genet. 112, 241-251]. To test this hypothesis, early and late replicating DNA of human diploid fibroblasts was labeled specifically by incorporating two different thymidine analogs [J. Aten (1992) Histochem. J. 24, 251-259; A. E. Visser (1998) Exp. Cell Res. 243, 398-407], during distinct time segments of S-phase. On mitotic chromosomes the amount and spatial distribution of early and late replicating DNA corresponded to R/G-banding patterns. After labeling cells were grown for several cell cycles. During this growth period individual replication labeled chromosomes were distributed into an environment of unlabeled chromosomes. The nuclear territories of chromosomes 13 and 15 were identified by additional chromosome painting. The distribution of early and late replicating DNA was analyzed for both chromosomes in quiescent (G0) cells or at G1. Early and late replicating DNA occupied distinct foci within chromosome territories, displaying a median overlap of only 5-10%. There was no difference in this regard between G1 and G0 cells. Chromosome 13 and 15 territories displayed a similar structural rearrangement in G1 cells compared to G0 cells resulting in the compaction of the territories. The findings demonstrate that early and late replicating foci are maintained during subsequent cell cycles as distinctly separated units of chromosome organization. These findings are compatible with the hypothesis that DNA organized into replicon clusters remains stably aggregated in non-S-phase cells.     

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。     

Influence of the maternal effect on allogenic inhibition of hematopoietic stem cells]

Bone marrow cells (0,5-10(6)) of female mice of CBA or C57BL strains were injected intravenously to lethally irradiated CBA, C57BL/6, (femaleCBA X maleC57BL/6)F1 and (femaleC57BL/6 X maleCBA)F1 mice. Spleen of recipients as assayed for colony count on the 9th day after bone marrow transplantation by the method of Till and McCullouch. Stem cells of CBA mice demonstrated failure of allogenic inhibition in (CBA X C57BL/6)F1 hybrid mice and formed the same number of colonies as in the spleen of syngenic recipients. The level of allogenic inhibition of CBA stem cells transplanted to (C57BL/6 X X CBA)F1 hybrid mice was 50%. Bone marrow cells of C57BL/6 mice formed colonies in spleen of (CBA X C57BL/6)F1 mice at least in 20 times less than in syngenic combination. In the transplantation of bone marrow from C57BL/6 mice to (C57BL/6 X CBA)F1 hybrid mice the allogenic inhibition was less pronounced (77-85%) as compared with the transfer of cells to (CBA X C57BL/6)F1 hybrid mice (95%). The sex of a recipient did not influence the number of formed colonies. The different level of allogenic inhibition of parental stem cells can not be explained by the effect of linkage with sex as the female of reciprocal hybrid mice have identical structure of sex chromosomes (X(CBA)XC57BL/6). The data obtained indicate that the maternal effect affects allogenic inhibition of stem cells in parent--F1 system. It is possible that the maternal influence may be determined by cytoplasmic factors of inheritance which affect the expressivity of recessive genes Hh, controlling the inheritance of specific haematopoietic cell antigens.     

The Correlation between the Chromosome Variation in Callus and Genotype of Explants of Arabidopsis thaliana

Twelve callus lines of Arabidopsis thaliana were derived from four types of explants excised from diploid plants of two ecotypes (Columbia and Wilna) and autotetraploid plants of the Wilna ecotype. Cytogenetic analysis of the chromosome variation in particular callus lines was carried out for primary culture and callus during 5 months of culture. Ploidy levels of interphase nuclei were estimated by counting the number and size of chromocentres and nuclei of interphase cells. The first polyploid cells in all callus lines were observed during callogenesis. In primary culture the ploidy level ranged between 2 and 15x (10-75 chromosomes). The frequency of polyploid cells was higher in the 5-month old callus culture, but the ploidy level was the same. In the callus lines derived from autotetraploid plants, cells with reduced chromosome number appeared quite frequently along with diploid and polyploid cells.     

Polymorphism of heterochromatin C-blocks of rye genome chromosomes in rye-wheat amphidiploids and their chromosome substitution lines

Polymorphism of heterochromatin C-blocks in chromosomes of rye genome has been studied in the F1BC1 hybrids and the D/A substitution lines of rye-wheat amphidiploids (Verasen x L374, Novosibirskaya x x L246)--secalotriticum for revealing cytogenetic markers of rye chromosomes. An increase in polymorphism for the presence and value of heterochromatin blocks in chromosomes of rye genome was shown in the F1BC1 hybrids ((Verasen x L374) x L145 x L145) and unstable genotypes of the F6BC1 chromosome substitution lines (line 118 (Novosibirskaya x L246) x Reso x Reso), line 104 ((Verasen x x L374) x Garmoniya x Garmoniya) that was related to activation of mobile genetic elements present in cereals. Heterochromatin markers of all seven chromosomes in rye genome were revealed. The polymorphism system of heterochromatin blocks may serve as a marker for specificity of the linear chromosome structure during reconstruction of synthetic cereal genomes, and as a test for cytological and morphogenetic stability of hybrid polygenomes in a series of generations.     

Silver fox gene mapping: conserved chromosome regions in the order Carnivora

Twenty-three silver fox x hamster somatic cell hybrid clones were used to assign 15 fox genes: GPI to chromosome 1; PGD to chromosome 2; MDH2 to chromosome 3; ESD to chromosome 6; LDHB to chromosome 8; NP to chromosome 10; LDHA to chromosome 11; APRT, ENO1, and PGM1 to chromosome 12; IDH1 and MDH1 to chromosome 16; and GLA, G6PD, and HPRT to the X chromosome. High-resolution G-banding of human, cat, mink, and fox chromosomes containing homologous regions (according to genetic maps) revealed regions of putative homology. The results lend support to the suggestion that the most considerable karyotypic reorganization of the ancestral genome in the order Carnivora occurred during Canidae formation. The details of karyotypic evolution in mammals are discussed.     

Cytological and breeding behavior of pentaploids derived from 3x × 4x crosses in potato

Cytology and breeding behavior of Solanum commersonii - S. tuberosum hybrids derived from 3 x x 4 x crosses was examined. The chromosome number of hybrids ranged from hypo-pentaploid (2 n=5 x - 8=52), to hyper-pentaploid (2 n=5 x + 7=67), with the euploid pentaploid 2 n=5 x=60 class predominant. The high variability in chromosome number of the 3 x x 4 x hybrids was attributed to the fact that meiotic restitution during megasporogenesis of the 3 x female may have involved poles with various chromosome numbers, resulting in 2 n eggs with 24-48 chromosomes. Microsporogenesis analyses provided evidence that chromosome pairing between S. commersonii and S. tuberosum genomes occurred. In addition, chromosome distribution at anaphase I and anaphase II revealed an average chromosome number of 29.5 and 29.1 per pole, respectively. To further study the extent of transmission of extra genome chromosomes from pentaploids, 5 x x 4 x and 4 x x 5 x crosses were performed, and the chromosome number of resulting progeny was determined. Ploidy ranged from 2 n=4 x=48 to 2 n=5 x=60 following 5 x x 4 x crosses, and from 2 n=4 x + 1=49 to 2 n=5 x=60 following 4 x x 5 x crosses. These results provided indirect evidence that the pentaploid hybrids produced viable aneuploid gametes with a chromosome number ranging from 24 to 36. They also demonstrated that gametes with large numbers of extra chromosomes can be functional, resulting in sporophytes between the 4 x and 5 x ploidy level. Fertility parameters of crosses involving various (aneuploid) pentaploid genotypes were not influenced by chromosome number, suggesting a buffering effect of polyploidy on aneuploidy. The possibility of successfully using (aneuploid) pentaploid genotypes for further breeding efforts is discussed.     

615小鼠染色体组型与G带带型分析

目的建立615小鼠标准染色体组型与G带染色体核型,提供可靠的细胞遗传学背景资料。方法成年615小鼠8只,雌雄各半,提取骨髓细胞,制片,镜检。确立615小鼠体细胞染色体数目。选择10个典型细胞测量染色体基本数据。G带染色。结果615小鼠的染色体数目为40条,XX为雌性,XY为雄性。所有染色体均为中部着丝点。X染色体相对长度仅次于第1对染色体,Y染色体的相对长度在第4对染色体和第5对染色体之间。G显带条数与小鼠有很大差异,接近于大鼠。结论615小鼠的核型为2n=40=2×19m＋（x）m＋（y）m,G显带共262条。