Analise citogenetica, citoquimica e ultraestrutural da espermiogenese de especies de Physalaemus e Pseudopaludicola falcipes com enfase a caracterização taxonomica de Physalaemus biligonigerus e P. fuscomaculatus

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

The genus Physalaemus, belonging to the family Leptodactylidae, shows extensive polymorphism and an abundance of cryptic species. At least four species are currently recognized in this genus. In this work, we investigated some aspects of the cytogenetics and spermiogenesis of several species in this genus, with particular emphasis on P. fuscomaculatus and P. biligonigerus. These two species are difficult to distinguish, mainly because of their considerable morphological similarities. A further problem is that the specific name fuscomaculatus has been applied to several populations of biligonigerus. AlI the specimens of P. fuscomaculatus, P. biligonigerus and P. aff. biligonigerus analyzed had 2n=22 chromosomes. All of the chromosomes had the same morphology, with the exception of pair 3 of P. fuscomaculatus, which was submetacentric, but metacentric in the other two species,. The short arm of chromosome 3 contained a block of heterochromatin which was Cband positive and was slightly longer in P. biligonigerus and P. aff. biligonigerus than in P. fuscomaculatus. The divergenge in morphology of chromosome 3 can be explained by the addition or delection of heterochromatin. The three species also showed a large block of pericentromeric heterochromatin in the pair 8, a small interstitial C-band, on the long arm of pairs 5 and 7, as well as a uni que ribossomal cistron, on the long arm of chromosome 9, coincident with the secondary constriction. P. aff. biligonigerus was the only species to have a large block of pericentromeric heterochromatin in the short arm of chromosome 9 and another one in the telomeric band of the long arme The nuclear basophilia during spermiogenesis in P. fuscomaculatus and P. biligonigerus (biligonigerus group), P. riograndensis, P. centralis, P. lisei, P. gracilis and P. cuvieri (cuvieri group) and P. petersi (pustulosus group) showed different responses with toluidine blue (TB) pH 4.0 and alkaline fast-green (AFG) after deamination. The spermatozoa of P.fuscomaculatus, P. biligonigerus, P. cuvieri and P. gracilis stained violet, whereas those of the other species showed different responses to TB. Except in P. gracilis, the spermatozoa of all species were positive to AFG, even after deamination. These results show that the DNA in the spermatozoa ofthese species is differently associated with proteins. This is the first description of such intrageneric variability in the Leptodactylidae. An ultrastructural analysis of the spermatozoa of P. fuscomaculatus, P. biligonigerus, P. gracilis and Pseudopaludicola falcipes, a genus considered to be a sister-group of Physalaemus, showed that the three species of Physalaemus had the same ultrastructural morphology, but differed from the spermatozoa of the Pseudopaludicola and other leptodactylids in that they had no axial rodo The results obtained here were insufficient to prove that P scomaculatus and P. biligonigerus are the same species, since the differences observed were very small and could reflect polymorphisms within populations. Although the genus Pseudopaludicola originated within the genus Physalaemus, the ultrastructure of P. falcipes spermatozoa differed from the latter group and was more similar to that of another leptodactylid, Odontophrynus cultripes. The use of a wider set of characters would help in elucidating the still confusing phylogenetic relationships among leptodactylids

ASSUNTO(S)

citoquimica citogenetica ultraestrutura (biologia)

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