首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Hybrid cells were isolated by fusing primary chicken myoblasts to HPRT-deficient rat L6 myoblasts and incubating the cells in medium containing HAT and ouabain. All hybrid clones contained both rat and chicken chromosomes and expressed a number of gene products characteristic of both species. Although all clones were capable of fusing spontaneously to form myofibers, immunofluorescence and isoenzyme analysis revealed only the rat forms of skeletal muscle myosin and MM-creatine kinase. No differentiated gene products of chicken origin were detected. Analysis of the expression of chicken HPRT revealed that some hybrid clones were capable of modulating this enzyme activity when switched from HAT medium into thioguanine medium and back into HAT, even though HPRT is normally a constitutively expressed enzyme. Parental control cells were incapable of this modulation phenomenon.  相似文献   

2.
Attempts were made to reprogram chick erythrocyte nuclei to specify the synthesis of chick myosin. Chick erythrocytes were fused with rat myogenic cells with the aid of UV-inactivated Sendai virus. In the heterokaryons and hybrid myotubes which resulted from this fusion, the erythrocyte nuclei resumed RNA synthesis and formed nucleoli. Although some new chick antigens developed in those myotubes which contained fully reactivated chick erythrocyte nuclei, accumulation of chick myosin could not be detected by immunological methods. Neither small heterokaryons nor large hybrid myotubes which were actively synthesizing rat myosin reacted with antibodies directed against chick myosin. A small number of mononucleated cells, believed to be synkaryons formed by mitotic division of heterokaryons, did, however, react strongly with antibodies directed against chick myosin and showed a cross striation typical of skeletal muscle. The frequency of such cells was too low, however, to permit karyological analysis or further characterization of the antigen. Hybrids between chick myoblasts and rat myoblasts produced both chick and rat myosin thus indicating that simultaneous translation of chick and rat mRNA for myosin in a common cytoplasm was possible. In summary the evidence obtained suggested that reprogramming of chick erythrocyte nuclei, if it did occur in the present system, was a rare phenomenon.The possibility that hybrids between chick erythrocytes and rat myoblasts expressed markers typical of an erythroid phenotype was examined by immune staining with antibodies directed against chick haemoglobin. The results suggested that haemoglobin was introduced into hybrid cells by erythrocytes which failed to lyse before fusion. The intensity of this immune fluorescence decreased with increasing time after fusion. The rate at which this decrease occurred was not affected by inhibition of RNA synthesis. Thus, there was no evidence for the accumulation of haemoglobin in the hybrid cells.  相似文献   

3.
《The Journal of cell biology》1983,97(5):1348-1355
Heterokaryons derived from polyethylene glycol-mediated fusion of myoblasts at different stages of development were used to investigate the transition of cells in the skeletal muscle lineage from the determined to the differentiated state. Heterokaryons were analyzed by immunofluorescence, using rabbit antibodies against the skeletal muscle isoforms of chicken creatine kinase and myosin, and a mouse monoclonal antibody that cross-reacts with chicken and rat skeletal muscle myosin. When cytochalasin B-treated rat L8(E63) myocytes (Konieczny S.F., J. McKay, and J. R. Coleman, 1982, Dev. Biol., 91:11-26) served as the differentiated parental component and chicken limb myoblasts from stage 23-26 or 10-12-d embryos were used as the determined, undifferentiated parental cell, heterokaryons exhibited a progressive extinction of rat skeletal muscle myosin during a 4-6-d culture period, and no precocious expression of chicken differentiated gene products was detected. In the reciprocal experiment, 85-97% of rat myoblast X chicken myocyte heterokaryons ceased expression of chicken skeletal muscle myosin and the M subunit of chicken creatine kinase within 7 d of culture. Extinction was not observed in heterokaryons produced by fusion of differentiated chicken and differentiated rat myocytes and thus is not due to species incompatibility or to the polyethylene glycol treatment itself. The results suggest that, when confronted in a common cytoplasm, the regulatory factors that maintain myoblasts in a proliferating, undifferentiated state are dominant over those that govern expression of differentiated gene products.  相似文献   

4.
Hybrids between a tumorigenic Chinese hamster cell line (DC3F-aza) and normal mouse thymus cells very rapidly lost most of their mouse chromosomes, whereas hybrids between tumorigenic mouse cell lines (either Cl.1D of L cell line origin, or PCC4-aza1 teratocarcinoma cells) and normal Chinese hamster thymus cells lost most of their hamster chromosomes. From three such fusion experiments, 20 cell lines were developed which all followed the same evolution, namely, the elimination of the majority of the chromosomes contributed by the normal thymus cell. In some hybrids, the elimination process resulted in the total absence of intact chromosomes contributed by the thymus cell parent. Such hybrids were distinguished from revertant parental cells growing in the selective hybrids were distinguished from revertant parental cells growing in the selective medium by the presence of at least one enzyme in their cell extracts which displayed the electrophoretic mobility of the enzyme of the thymus cell parent. These observations, together with data from other reports, suggest that, as a rule, interspecific cell hybrids which develop upon fusion between normal diploid cells and tumorigenic cell lines maintain the chromosomes of the latter and eliminate preferentially many or most of the chromosomes contributed by the normal cell parents, independent of the respective species of the parental cells.  相似文献   

5.
Leaf and flower oil terpene composition and several plant morphological characteristics of 17 Mentha × verticillata hybrids were analysed during two growing seasons (1988 and 1989). The data obtained were used to study the phenotypic plasticity, the genotypic variation and the genetic variation for phenotypic plasticity. All plants showed high leveis of phenotypic plasticity for both oil chemical and morphometrical parameters. Higher degrees of genotypic variation were found among the plants for oll components while a higher phenotypic plasticity was observed for morphological parameters. Temperatures and rainfall data were collected during the growing seasons and correlated to the data obtained from plant oil and morphology. Low levels of phenotypic plasticity and high degrees of genotypic variation were found to form outliers in the population of M. x verticillata hybrids. The results obtained confirm a significant effect of environmental conditions on the physiology and morphology of the genus Mentha.  相似文献   

6.
DNA isolated from mammalian cell nuclear reveals discrete size patterns when partially digested with micrococcal nuclease. The DNA repeat lengths from different tissues within a species or from different species may vary. These differences have been attributed to the presence of different species of histone H1. To examine the nature of regulation of DNA repeat lengths and their possible relationship to histone H1, we have selected several mouse and human cell lines that differ in their DNA repeat lengths and examined them and their cell hybrids. 24 mouse X human and five mouse X mouse hybrid cell lines were analyzed. All the interspecific hybrids exhibited the repeat pattern characteristic of the murine parent. The mouse intraspecific hybrids had a repeat pattern of only one of the parents. We conclude that the partial human chromosome complements retained in the hybrids assume the repeat lengths exhibited by the mouse cells. Because H1 histones have been implicated in the determination of DNA repeat lengths, we also investigated the regulation of H1 histone expression in these cell hybrids. Purified H1 histones were radioactively labeled in vitro, and individual subfractions were subjected to proteolysis followed by gel electrophoresis. The resulting partial peptide maps off H1 histone subfractions A and B were distinguishable from one another and from different cell lines. In the mouse X human hybrids analyzed, only the mouse H1 histones were detected. These observations were extended to H2b by analysis of the hybrid cell histone by Triton-acid-urea gels. Neither the DNA repeat length nor histone expression is affected by the presence of any specific human chromosome. The fact that human genes are expressed in these hybrids suggests that the H1 histones of one species is able to interact with the chromatin of another species in a biologically funtional conformation. Analysis of the intraspecific PG19 X B82 (mouse X mouse) hybrids reveals the presence of H1 histone subfractions of the B82 mouse cells. Because these hybrids exhibit the nucleosome repeat length only of the PG19 cells, it appears that if histone H1 plays a role in determining the repeat length it does so in consort with other nonhistone chromosomal proteins.  相似文献   

7.
The horn fly Haematobia irritans (Diptera: Muscidae) is a blood obligate ectoparasite of bovids that causes annual losses to the U.S. beef cattle industry of over US$1.75 billion. Climate warming, the anthropogenic dispersion of bovids and the cross‐breeding of beef cattle with other bovid species may facilitate novel horn fly–host interactions. In particular, hybridizing yaks [Bos grunniens (Artiodactyla: Bovidae)] with beef cows (Bos taurus) for heterosis and carcass improvements may increase the exposure of yak × beef hybrids to horn flies. The present paper reports on the collection of digital images of commingled beef heifers (n = 12) and F1 yak × beef hybrid bovids (heifers, n = 7; steers, n = 5) near Laramie, Wyoming (~ 2200 m a.s.l.) in 2018. The total numbers of horn flies on beef heifers and F1 yak × beef heifers [mean ± standard error (SE): 88 ± 13 and 70 ± 17, respectively] did not differ significantly; however, F1 yak × beef steers had greater total horn fly abundance (mean ± SE: 159 ± 39) than female bovids. The present report of this experiment is the first such report in the literature and suggests that F1 yak × beef bovids are as susceptible as cattle to horn fly parasitism. Therefore, similar monitoring and treatment practices should be adopted by veterinarians, entomologists and producers.  相似文献   

8.
9.
We have examined cell hybrids derived from L6J1 rat myoblasts and A9 mouse fibroblastic cells for expression of the myogenic phenotype. Initial results showed that hybrid cells were no longer able to form myotubes and hence showed extinction of the myogenic phenotype. We then proceeded to characterize the pattern of protein synthesis in these cells using two-dimensional gel electrophoresis. Although we did detect extinction of synthesis of a small number of myoblast polypeptides in the hybrids these did not appear to be rat myoblast specific. Instead they correlated well with polypeptides lost upon viral transformation in another rat cell line. Analysis of the ability of parental cells and hybrids to grow in soft agar confirmed that both A9 cells and hybrids were more transformed than the parental L6J1 cells. The results are consistent with the interpretation that extinction of the ability to form myotubes is due to either transformation and/or a disrupted cell organization but is unlikely to be due to specific extinction of myoblast specific polypeptides, at least at the level detectable by 2D gel electrophoresis.  相似文献   

10.
Regulation of gene expression in somatic cell hybrids: a review   总被引:6,自引:0,他引:6  
R L Davidson 《In vitro》1971,6(6):411-426
  相似文献   

11.
The human fibroblast interferon gene beta 1 was mapped to human chromosome 9. Sequence homology with a beta 1 cDNA clone was detected in both genomic DNA and induced mRNA of human/mouse or human/hamster somatic cell hybrids containing human chromosome 9, but not in lines lacking this chromosome or those retaining a complex translocation involving chromosomes 9 and 11. Interferon mRNA that did not share sequence homology with the beta 1 cDNA clone was detected in lines containing human chromosomes 2 and 5 but lacking chromosome 9, suggesting the presence of other unlinked interferon sequences in the human genome.  相似文献   

12.
A rat hepatoma cell line (H4AZC2) was characterized with respect to seven liver-specific phenotypes. Ten clones from the fusion of H4AZC2 and mouse L cell were analyzed for the expression of these phenotypes. The only hepatic function retained by the hybrid clones was rat albumin synthesis which continued at reduced levels relative to the hepatoma parent. Rat albumin cDNA analysis of RNA from parental and hybrid cells indicated that the reduction in albumin production observed in the hybrids was reflected in coordinate reduction of cytoplasmic rat albumin mRNA.  相似文献   

13.
14.
Protoplasts from phosphinotricin resistant M. sativa and M. varia cell lines carrying an amplified glutamine synthethase gene were fused with leaf protoplasts of kanamycin resistant M. varia transformants. The dominant nature of both PPT and kanamycin resistant traits was shown by the double resistant phenotype of the intra- and interspecific cell hybrids obtained. The presence of amplified GS gene in the hybrid genomes and the expression of chimeric neomycin phosphotransferase II gene was detected. The highly embryogenic character of the M. varia parent was not expressed after cell fusion. All hybrid cell lines with the double resistant phenotype showed non-morphogenic growth similarly to the PPT resistant parent. The possible role of GS gene amplification and other factors in the dominant behaviour of unorganized cell growth in alfalfa somatic hybrids is discussed.  相似文献   

15.
16.
17.
18.
19.
A Monte Carlo simulation was conducted in order to determine the size and power of two proposed tests (the covariance and correlation tests) for three-factor interaction in 2 × 2 × 2 contingency tables. Results were compared to the log-odds ratio test statistic. Simulation showed the correlation test to be more conservative than the covariance test, but less so than the log-odds ratio test. However, the correlation test was the most powerful among the three tests.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号