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  • 1
    ISSN: 1432-1432
    Keywords: Zfy-Zfx genes ; Gene evolution ; Oryzomyne-akodontine rodents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Zinc finger-Y (Zfy) and zinc finger-X (Zfx) genes were analyzed by Southern blotting in male and female specimens of 10 species belonging to the oryzomyne-akodontine stock of Cricetidae rodents. DNA fragments were used as characters to construct a parsimony tree of the genes. Zfx and Zfy trees in general coincide with the evolutionary history of the taxa. Both trees show Oryzomys longicaudatus genes as the outgroup whereas Akodon xanthorrhinus genes are also distant from those of the other species. Oxymycterus rufus and Bolomys obscurus share related sequences, while genes from the other six Akodon species form a group of their own. It was found that 9 out of the 10 species analyzed show Zfy amplification in a range varying from 2 to 24 copies and with a pattern that is clade specific. The estimation of the average changes per character strongly suggests that Zfy has evolved more rapidly than Zfx; our estimates of the rate of nucleotide substitution are 4.6 times higher for Zfy than for Zfx.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1432
    Keywords: Pongidae ; Chromosome ; Karyotype ; Restriction enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The pattern of banding induced by five restriction enzymes in the chromosome complement of chimpanzee, gorilla, and orangutan is described and compared with that of humans. The G banding pattern induced by Hae III was the only feature common to the four species. Although hominid species show almost complete chromosomal homology, the restriction enzyme C banding pattern differed among the species studied. Hinf I did not induce banding in chimpanzee chromosomes, and Rsa I did not elicit banding in chimpanzee and orangutan chromosomes. Equivalent amounts of similar satellite DNA fractions located in homologous chromosomes from different species or in nonhomologous chromosomes from the same species showed different banding patterns with identical restriction enzymes. The great variability in frequency of restriction sites observed between homologous chromosome regions may have resulted from the divergence of primordial sequences changing the frequency of restriction sites for each species and for each chromosomal pair. A total of 30 patterns of banding were found informative for analysis of the hominid geneaalogical tree. Using the principle of maximum parsimony, our data support a branching order in which the chimpanzee is more closely related to the gorilla than to the human.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The karyotype of moose (2n=68) is characterized by very large C-bands close to the centromeres of most chromosomes. The C-banded material represents 40% of the genome. For further characterization of the heterochromatin chromosome spreads were treated with restriction endonucleases and the restriction enzyme (Re) banding pattern was analysed. HaeIII, AluI, MboI, RsaI and HinfI produced informative Re-bands. DdeI induced an even digestion with no banding. Staining with chromomycin A3 produced bright fluorescence in regions corresponding to C-bands. Labeling with BrdUrd during late S phase differentiates four regions in the C banded area. The sequence of these regions from centromere to telomere are: late, early, late and early replicating. The authors propose the existence of five satellite DNA families with distinctive characteristics of G-C and A-T richness and different replication timing, and point out the different clusters for the endonucleases detailed above and their varying location in the chromosomes examined.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 42 (1986), S. 622-624 
    ISSN: 1420-9071
    Keywords: Karyological conservatism ; camelids ; camelids karyology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Llama, guanaco, vicuna and alpaca show similar diploid numbers, gross chromosomal morphology and homologous G, C and NOR banding patterns. This chromosomal homology is also found in the two-humped camel and very probably in the one-humped camel as well. These findings indicate that the camelid karyotype can probably be traced back to early Miocene times. This probably represents the most extreme case of chromosomal conservatism among mammals.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1572-9931
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have analyzed the pattern of methylation of rearranged and germ line C K genes in DNA samples from human B-type chronic lymphatic leukemia lymphocytes and normal fibroblasts, and from granulocytes, T-, and non-T-lymphocytes separated from normal blood. C K alleles are flanked by one Hpall site on each side. Leukemic B-CLL DNA from five patients showed demethylation of these two sites in the productively rearranged allele and methylation of both sites in the nonexpressed allele whether rearranged or in germline configuration. Non-T-lymphocytes from normal individuals also showed part of the C K genes to have demethylation of both Hpall sites. On the other hand, C K genes from normal granulocytes, Tlymphocytes, and four of five fibroblast samples were methylated in one or both Hpall sites. We propose that in Blymphocytes, demethylation of C K alleles is a specific event taking place in the expressed genes and being associated with an increased transcriptional activity of the gene. In addition to this specific demethylation, there is also an unspecific one that may appear in cells with silent C K genes and that do not modify the expression of the gene.
    Type of Medium: Electronic Resource
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