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PubMed1976

Further studies on polyploid amphibians. V. C-banding in diploid and tetraploid species of Odontophrynus.

C-band patterns of some Odontophrynus species from Brazil are described. O. americanus 2n and 4n are cryptic species similar to O. cultripes 2n, but their C-banding patterns are different. In O. americanus 2n the C-band appears at the secondary constriction of chromosomes 4. In O. americanus 4n and O. cultripes the C-band appears at the secondary constriction of chromosomes 11. O. cultripes chromosomes 2,3 and 6, have also an intercalary band. Furthermore, fine centromeric bands in several weeks old preparations of these species were observed. The possibility of a structural or chemical heterogeneity of those heterochromatic regions is discussed.

Animals↗
PubMed1975

Are all the neuronal nuclei polyploid?

The DNA analysis of rat brain nuclei by two independent cytochemical methods, namely microfluorometry and UV-absorption, brings completely different results to those published previously by many investigators. The neuronal nuclei possess twice as much DNA as the glial nuclei.

Animals↗
PubMed1986

Albumin evolution in polyploid species of the genus Xenopus.

Electrophoresis of serum from 21 Xenopus species and subspecies reveals variable numbers of albumin bands. The diploid X. tropicalis has one albumin, while the tetraploid species (laevis, borealis, muelleri, clivii, fraseri, epitropicalis) have two. The octoploid species (amieti, boumbaensis, wittei, vestitus, andrei) have two to three bands, and the dodecaploid X. ruwenzoriensis has three. The molecular weight of the Xenopus albumins varies from 68 kd (in the tropicalis group) to 74 kd. The subspecies of X. laevis possess two albumins of different molecular weights (70 and 74 kd), whereas most species have only 70-kd albumins. Peptide maps have been obtained from albumin electromorphs by limited proteolysis in sodium dodecyl sulfate (SDS) gels, using S. aureus V8 protease. The peptide patterns produced by electromorphs from the same tetraploid Xenopus species generally differ from each other, suggesting that the two albumin genes contain a substantial amount of structural differences. In addition, the peptide maps are diagnostic for most tetraploid species and for some subspecies of X. laevis as well. Proteolysis of albumins from most octoploid and dodecaploid species results in patterns which are very similar to the ones produced by the electromorphs from X. fraseri. The albumins of X. vestitus differ from those of the other octoploid species. X. andrei possesses two fraseri-type and one vestitus-type albumin, which indicates that it probably originated by allopolyploidy.

Albumins↗
PubMed1981

Escape efficiency of diploid and polyploid frogs: a comparison of Odontophrynus cultripes (2n = 22) and O. americanus (4n = 44).

The escape efficiency of two closely related species of frogs, Odontophrynus cultripes (2n = 22) and the tetraploid O. americanus (4n = 44), were compared in a shuttle box and under simulated naturalistic conditions. O. americanus was generally superior to O. cultripes, and females tended to outperform males within both species. The relative inefficiency of O. Cultripes escape behavior was examined in light of the animals' having an elaborate, passive defense mechanism in the form of well marked venom glands. Escape efficiency was highly variable in both species. Possessing twice the amount of DNA, the tetraploid behavioral variation was paradoxically less than that of the diploid, but compatible with what has been found for morphological characters in other organisms.

Animals↗
PubMed1994

Different species-specific chromosome translocations in Triticum timopheevii and T. turgidum support the diphyletic origin of polyploid wheats.

Triticum timopheevii ssp. timopheevii and T. timopheevii ssp. araraticum were analysed by sequential N-banding and genomic in situ hybridization. Three chromosomes, 6At, 1G and 4G, were involved in At-G intergenomic translocations in all six lines analysed. These chromosomes may be derived from a cyclic translocation that is species-specific to T. timopheevii. In contrast, Triticum turgidum has a species-specific cyclic translocation involving chromosomes 4A, 5A and 7B. The discovery of different species-specific chromosome translocations supports the diphyletic hypothesis of the evolution of tetraploid wheats. The results from genomic blocking analysis also revealed that the chromosomes of Aegilops speltoides are closer to the G genome than the B genome chromosomes. The possible role of species-specific translocations in the evolution of wheat is discussed.

Chromosome Banding↗
PubMed1978

Two new polyploid Xenopus species from western Uganda.

2 new species of the anuran genus Xenopus have been found in western Uganda: X. ruwenzoriensis sp.n. with the hexaploid chromosome number of 108 in the Semliki Valley, west of the Ruwenzori, and X. species nova with the tetraploid chromosome number of 72 in and near lake Bunyoni.

Animals↗