Orfeo Picariello

Sex steroids and postreproductive refractoriness in the lizard, Podarcis s.sicula

Abstract The evolution of sex steroids in the plasma and gonads of the lizard Podarcis s. sicula during the postreproductive period shows that these hormones could be involved in determining refractoriness. In the male, during this phase, the oestradiol could lower the hypothala‐mo‐hypophyseal system through a negative feed‐back. In the female a similar role could be assigned to progesterone.

The annual cycle of oviduct in Tarentola m. mauritanica L. (Reptilia, Gekkonidae)

The oviduct of Tarentola mauritanica from southern Italy can be divided cranio-caudally into 5 regions: infundibulum that opens into the coelomic cavity, tuba, isthmus, uterus and vagina which opens into the cloaca. The changing morphology of these regions during the reproductive cycle is described. Unlike the male, the genital duct (epididymis) which is fully developed and secretory throughout the year, the oviduct shows a marked annual cycle with maximum activity in May-July. Seasonality would allow optimization of the reproductive effort. This gecko shows three ovulatory waves, namely in late May, June and July; at each time one calcareous cgg is produced per ovary. There is a short period of egg retention in the oviduct. The main breeding period takes place in spring; sometimes a second optional breeding may occur in autumn. Sperm is preserved inside the crypts of the tuba until the next spring.

Estimating genetic variation from larvae and adults of mayflies: An electrophoretic analysis of three species of heptageniidae (ephemeroptera)

Abstract Genetic variation in larvae and imagines of three species of Heptageniidae from central Italy, Ecdyonurus sp. (venosus group), Elec‐trogena grandiae (Belfiore, 1981), and Electrogena lateralis (Curtis, 1834) was studied by starch‐gel electrophoresis. Thirteen enzyme systems were analysed for a total of 20 loci (Aat, Ada, Adk‐1, Adk‐2, Ck‐1, Ck‐2, Est‐1, Est‐2, α‐Gpdh, Gpi, La‐1, La‐2, Mdh‐1, Mdh‐2, Me‐1, Me‐2, Mpi, Pap, Pgm‐1, Pgm‐2), 15 of which were expressed in adults and 16 in the larvae. Only 11 loci (Aat, Ada, Est‐2, Gpi, La‐2, Mdh‐1, Me‐2, Mpi, Pap, Pgm‐1, Pgm‐2) were shared by larvae and adults. Observed heterozygosities were always lower than expected values; higher values were observed in larvae than in adults. Fixation indices and genetic distances were higher in the adults; however, the two genera were better discriminated using the larval samples. In conclusion, comparisons using larvae and adults simultaneously should be avoided, and absolute values of genetic identities and genetic...

Characterization of two major satellite DNAs specific to the genus Discoglossus (Amphibia, Anura)

Abstract Two new high repetitive DNAs were isolated from Discoglossus pictus genomic DNA digested with StuI. Sequence analysis of clones indicated two types of repetitive units 143–148 bp and 170–177 bp long, respectively. Southern blot analyses show ladders of bands indicating that both repetitive units are organized in long tandem arrays and belong to two different satellite DNAs that were named Dp-sat2 and Dp-sat3. A similar ladder of bands was also produced when genomic DNA was digested with ClaI in the case of Dp-sat2, or with ScaI in the case of Dp-sat3. Quantitative dot-blot analyses indicate that Dp-sat2 and Dp-sat3 account for about 2.6% and 2.2%, respectively, of the D. pictus genome. Considering that D. pictus has a genomic DNA content of 10.5 pg/N, our data indicate that Dp-sat2 and Dp-sat3 repetitive units are present in about 2.3×106 and 1.6×106 copies per diploid genome, respectively. Dp-sat2 and Dp-sat3 probes produced the same patterns of hybrid bands in Southern blots and the same genomic content in dot-blots in all the other Discoglossus species, except D. montalentii which showed a different band pattern and genomic content. The chromosomal distribution of the two StuI satellites shows some similarities: both Dp-sat2 and Dp-sat3 probes mainly labelled the pericentromeric regions of the large chromosome pairs 1–5 and 7. Moreover, probes from both satellite DNAs also produced faint fluorescent mini-spots along almost all chromosome pairs. These data suggest that both satellite DNAs have two types of organization, one in long arrays localized in pericentromeric positions, and the other in short arrays dispersed in the genome.

Morphological and Electrophoretic Evidence for a New Species of Electrogena from Central Italy: Description of E. lunaris sp. n. (Ephemeroptera: Heptageniidae)

A population of Electrogena from central Apennine (Italy), previously attributed to E. later‐alis (Curtis) proved to be a new species after electrophoretic analysis. Imagines of the new species, named E. lunaris sp. n. differ from E. lateralis only by body and wing colouration. Larvae can be identified by numerical methods. Electrophoresis indicated three loci (Aldh, Gdh, Mpi) that are diagnostic between the syntopic populations of E. lunaris and E. lateralis and the allele frequencies of three other loci (Est‐2, Mdh‐1, Pgm) were statistically different between the two species.

Karyological divergence of a Moldovan population of Rana dalmatina Bonaparte, 1838

A karyological study conducted by both conventional and banding staining methods (Ag-NOR-, CMA3, and C-banding) evidenced a peculiar heterochromatin pattern on chromosomes of Moldovan specimens of the agile frog, Rana dalmatina. As is normal for all agile frogs, the Moldovan population presented 2n = 26 chromosomes, with NOR loci on the short arms of the third chromosome pair, but differed in showing heavy centromeric, CMA3 positive C-bands on the seventh chromosome pair, and light centromeric, DAPI positive C-bands on five chromosome pairs. In contrast, Moldovan specimens showed no significant difference in two segments of the 16S mitochondrial rRNA gene and in the S1 satellite DNA sequence and organization, in comparison with the GenBank deposited 16S rDNA and S1 DNA satellite sequences of R. dalmatina. Molecular similarity and chromosomal differences between agile frogs from Moldovan and extra-Moldovan populations are discussed.

Arginine-vasotocin as an inhibitor of gonadal activity in the male of the lizard, Podarcis s-sicula Raf.

Abstract Adult males of the lizard, Podarcis s. sicula Raf., were treated with arginine-vasotocin (AVT) during the reproductive period to investigate its effects on the spermatogenic and endocrine activities of the testis. Results showed that AVT can affect gonadal activity by blocking spermiohistogenesis and inhibiting interstitial tissue.

The Annual Spermatogenetic Cycle of Tarentola mauritanica L. (Reptilia, Gekkonidae)

The gecko Tarentola mauritanica L. of southern Italy shows seemingly a tendentially continuous spermatogenetic cycle throughout the year. However, the amount of sperms produced at the level of the seminiferous tubules varies remarkably in the different months of the year: it is maximum in spring and in early summer, whereas it markedly decreases in June-July, when a drastic reduction in spermatogonial mitoses is observed. The slowing down in the spermatogonial activity not involves the complete disappearance of any definite cell stage of gametogenesis, but spermatogenesis is strongly reduced. In winter there is another slowing down in spermatogenesis, anyhow some new spermatozoa continue to form and to be released, though in extremely limited amounts. The general pattern of spermatogenesis is, therefore, of mixed or thermo-rigostatic type. The epididymis appears well developed throughout the year, showing only in wintera decreased amount of secretion. The epididymal tail acts as a system of spermatozoa storage, so that it is always full of sperms also in the period when the gametogenetic activity is at its minimum.

Sex differences in liver non-specific esterases of the green frog Rana esculenta

1. Liver esterases of the green frog Rana esculenta have been fractionated on disc electrophoresis, thin-layer electrofocusing and column electrofocusing. 2. The enzyme resolves in several molecular forms some of which result sex dependent, since they disappear in castrated animals and can be induced by sex hormone administration. 3. The enzyme molecular forms which depend on female hormones might be involved in cellular modifications of hepatocytes related to yolk protein synthesis. induced by sex hormone administration. 3. The enzyme molecular forms which depend on female hormones might be involved in cellular modifications of hepatocytes related to yolk protein synthesis.