Ernesto Capanna

Abstract The African grass rat, Arvicanthis sp., from Benin shows sex‐chromosome polymorphism for the presence in the karyotype of three X‐chromosome forms: subtelocentric (Xst), submetacentric (Xsm), and metacentric (Xm). Here we report statistically significant differences of diploid genome size (gs) among individuals, from 6.22±0.06 pg to 6.80±0.10 pg, depending on the X‐chromosome form. The evaluation of the total and X‐chromosome heterochromatin content alone (Xst: 2.16±0.22%; Xsm: 5.02±0.22%; Xm: ...

Abstract  Nitric oxide (NO) is a new inter- and intra-cellular messenger, produced by the enzyme nitric oxide synthase (NOS), converting arginine in citrulline plus NO. This mechanism has been first described in mammals and found in different vertebrates and in higher invertebrates. No data are available for low invertebrates. The presence of NOS and the role of NO have been studied

... ANNA LOY FRANCESCA BEOLCHINI SIMONA MARTULLO ERNESTO CAPANNA Dipartimento di Biologia Animale e dell'Uomo, Università «La Sapienza», via Borelli 50, I-00161 Roma (Italy) ABSTRACT ... Field work was carried out from April 1992 to May 1993. ...

Architectural pattern of the telencephalon, diecenphalon and mesencephalon of Polypterine fishes (Osteichthyes, Brachiopterygii).The architectural pattern of the telencephalon, diencephalon and mesencephalon was studied in the Polypterine fishes. Brains of Calamoichthys calabaricus and Polypterus senegalus were examined using Golgi-Cox impregnations and Bodian gold-silver staining. The structure of these neural areas resembles the organization in the Actinopterygii and Dipnoi. Nevertheless, relevant peculiarities

The house mouse Mus musculus domesticus is characterized by more than 100 metacentric populations, due to the occurrence of Robertsonian (Rb) fusions, together with the standard all-telocentric karyotype (2n = 40). We examined G-banded karyotypes of 18 mice from 10 localities in Sicily and describe 3 new metacentric populations: 'Ragusa Ibla' (IRAG), 2n = 33-36, Rb(2.4), Rb(5.6), Rb(9.16), Rb(13.17); 'Piana degli Albanesi' (IPIA), 2n = 23, Rb(1.18), Rb(2.15), Rb(3.5), Rb(4.12), Rb(6.11), Rb(7.8), Rb(9.16), Rb(10.14), Rb(13.17); 'Trapani' (ITRA), 2n = 22, Rb(1.18), Rb(2.15), Rb(3.7), Rb(4.12), Rb(5.9), Rb(6.11), Rb(8.16), Rb(10.14), Rb(13.17). Three mice belonged to the previously reported 'Castelbuono' race (ICAS), 2n = 24, which is very similar to the nearby 'Palermo' (IPAL) race, 2n = 26. Three Rb fusions not yet observed in wild mouse populations were identified: Rb(3.5), Rb(3.7) and Rb(5.9). Rb fusions shared among 4 races (IPIA, IRAG, ICAS, and IPAL) allowed us to describe their potential phylogenetic relationships. We obtained 2 alternative phylogenetic trees. The differences between them are mainly due to various modes of formation of IPIA and ITRA. In the first hypothesis, the specific Rb fusions occurred independently. In the second, those of IRAG originated from those of IPIA via whole-arm reciprocal translocations.

Seventeen species of bats of Venezuelan highland forest, pertaining to three families (Phyllostomidae, Mormoopidae, and Vespertilionidae) were considered for genome size (g.s.) evaluation. Feulgen stained lymphocytes were microdensitometrically evaluated from two blood smears for each individual. The g.s. we got range from 4.5 pg forLonchorhina aurita (Phyllostominae, Phyllostomidae) to 5.9 pg forCarollia perspicillata (Carollinae, Phyllostomidae). These values are among the

Chiasma number and distribution were analysed in male house mice from a karyotypic hybrid zone between the CD race (2n = 22) and the standard race (2n = 40) located in central Italy. Chiasma repatterning occurs across the transect. The overall trend produces a diminution of chiasmata in the mice with CD chromosomal background. The progressive reduction of chiasmata indicates that genes could pass from one race to another in an asymmetrical way: from metacentric races to the standard population.

The mammalian cell nucleus consists of numerous compartments involved in the regular unfolding of processes such as DNA replication and transcription, RNA maturation, protein synthesis and cell division. Knowledge is increasing of the relationships between high-order levels of chromatin organization and its spatial organization, and of how these relationships contribute to the various functions carried out in the nucleus. We have studied the spatial arrangement of mouse telocentric chromosomes 5, 11, 13, 15, 16 and 17, some of their metacentric Robertsonian derivatives, and X and Y chromosomes by whole chromosome painting in male germ (spermatogonia, pachytene spermatocytes and spermatids) and Sertoli cells of homozygous and heterozygous individuals. Using dual-colour fluorescence in situ hybridization we found that these chromosomes occupy specific nuclear territories in each cell type analysed. When chromosomes are present as Robertsonian metacentrics in the heterozygous state, th...

The aim of the present study was to assess the degree of genetic variation and divergence among six populations of Calomys hummelincki, a phyllotine rodent distributed in northern South America. With this information we will try to evaluate the two hypotheses of possible colonization and differentiation of this group of rodents postulated by Baskin and Reig. We studied 34 loci by electrophoretic analysis: 21 were monomorphic for all populations and 13 were polymorphic in at least one population, being P1% = 21.6% the mean value for all populations. The mean value of heterozygosity per locus was H = 0.075. Low values of genetic distance were observed among populations of the Llanos region (0.001 < D < 0.006). There was a larger genetic distance (D = 0.024) between the population from Isiro, in the northwestern semiarid region, and those from the Llanos region. The insular population of Aruba displayed the lowest value of genetic distance with the population from Isiro (D=0.014)...

The female gonads of moles (genus Talpa) are composed of a cortex, functioning as an ovary, and a medulla, which is structurally similar to that of the testis. In the female reproductive apparatus there are masculine glandular annexes, such as a bilobate prostate, two Cowper glands, and a penis-like clitoris. All these features have recently led to the hypothesis of the presence of hermaphroditism due to sex-reversal in Talpa. The purpose of this study is to understand the functional significance of the structural organization of the female gonads in order to verify this hypothesis. Histological, histochemical and ultrastructural analyses have been carried out on several gonads of both sexes of two species: T. europaea and T. romana, including three fetuses. In both species, the cortical region of the female gonad shows a regular oogenetic activity. While the medulla is composed of interstitial cells that are partly organized in cord-like structures, no spermatogenetic activity has ...

Chromosome rearrangements are often an important factor in the origin of new species. They have a potential to affect the fitness of hybrids, and so to stop gene flow and strengthen genetic divergence between intraspecific chromosomal races. Debate still rages over which model best explains chromosomal speciation, the main difficulty being the lack of historical records. We now present data

ABSTRACT The karyotypes of six species of Mediterranean mullets have been studied: Mugil cephalus, Liza aurata, Liza saliens, Liza ramada, Chelon labrosus and Oedalechilus labeo. The diploid number in all these species is 2n=48. On the basis of the morphology of the karyotype, 3 cytotaxonomic groups are proposed: a) Mugil cephalus, all the chromosomes of which are acrocentric; b) Liza and Chelon with one pair of subtelocentrics; c) Oedalechilus with one pair of telocentrics with a very small arm. The karyologic finding is discussed with regard to the position of the Mugilidae in systematic studies.

... by E. Olmo and CA Redi © 2000 Birkhauser Verlag/Switzerland Chromosomes yesterday: a century of chromosome studies Ernesto Capanna Department ... Some historians of science assert that the credit for this idea should go to Thomas Harrison Montgomery (1873-1912) who ...

The nuclear DNA content was evaluated in 48 species of Neognathae birds belonging to 13 orders, namely Anseriformes, Charadriiformes, Columbiformes, Ciconiiformes, Falconiformes, Galliformes, Gruiformes, Passeriformes, Pelicaniformes, Phoenicopteriformes, Piciformes, Psittaciformes and Strigiformes. The DNA content, expressed in pg/nucleus, ranges from 2.81 to 4.97. The genome size variability within and among families is discussed on the basis of the Hinegardner's (1976) model of genome evolution.

1. Highly repetitive, middle repetitive and single copy DNA were evaluated in 19 species of birds, belonging to nine orders, by means of a reassociation kinetics method. 2. A rather uniform pattern is present in all the species studied (single copy = 60-75%; middle repetitive = 13-20% and highly repetitive 10-20%). 3. Reassociation kinetics of fragments of different length confirms the presence of a long period interspersion pattern. 4. Among different orders, no significant differences are observed. 5. DNA sequence organization seems to be related to genome size, with an inverse correlation between DNA nuclear content and amount of interspersed repetitive sequences.

ABSTRACT Sono stati studiati i cromosomi di Barbastella barbastellus ed è stata eseguita l'analisi cariometrica. Il numero diploide è risultato, su cellule somatiche in cultura 2 n = 32. Il cariotipo è costituito da 9 coppie di grandi cromosomi metacentrici, 1 coppia di cromosomi metacentrici di piccole dimensioni ritenuti morfologicamente identici a cromosomi ritrovati in altri Vespertilionidi, 3 coppie di piccoli cromosomi acrocentrici e 2 coppie di cromosomi puntiformi. L'eterocromosoma X è un grande metacentrico e l'Y è un cromosoma puntiforme. È stata tentata una interpretazione dell'evoluzione cromosomica nell'ambito di 4 specie di Vespertilionidi per le quali gli autori hanno effettuato una precisa analisi cariometrica.

ABSTRACT Histophotometric evaluation of the DNA content of the post-kinetic nuclei (lymphocytes) has been performed in 8 species of Palearctic Microchiroptera: Rhinolophus ferrumequinum, R. euryale, R. hipposideros, Miniopterus schreibersi, Pipistrellus savii, P. kuhli, Myotys myotis and M. capaccinii. The results obtained are compared with the known data (CAPANNA and CIVITELLI 1970) on the morphology of the karyotype of these species and are discussed whith a view to explaining the relationships between chromosome transformations and variations in DNA content.