Chromosome studies in North-Western Sicily males of Rhynchophorus ferrugineus

Rhynchophorus ferrugineus (Olivier), known as red palm weevil (RPW) was accidentally introduced and established in Sicily (Italy) since 2005. As like in other Mediterranean sites, RPW has been causing extensive damage to palm trees and on its new host Phoenix canariensis Chabaud (Canary Island palms), acquired concomitantly with the colonization of the area. RPW shows a good ecological plasticity and slightly but significant morphological polymorphism (colour patterns and length of the rostrum in male individuals) that can be appreciated within different geographical populations. The aim of the present work was to investigate if this ecological plasticity and phenotypic variability can be accompanied by features in chromosomes like changes in diploid number or chromosome morphology, when compared to other RPW populations. Literature data on karyotype analysis reveals a diploid number (2n = 22). In this paper, the karyotypes of different morphotypes of RPW Sicilian populations, collected from P. canariensis, were analysed using conventional staining, C-banding and sequential staining with the fluorochromes chromomycin-A3/4-6-diamidino-2-phenylindole (CMA3/DAPI). The analyses of metaphases obtained from the testes of adults showed that the species has 2n = 22 chromosomes, with 10 autosomal pairs and a sex chromosome pair. The eu-heterochromatic composition investigated with CTG banding, DAPI, CMA3, and NOR do not indicate any peculiarity in the populations investigated. R. ferrugineus has a Coleoptera Curculionoidea chromosomal asset and functional compartimentalization. RPW presents a karyotype with intermediate characteristics between Dryophthorinae and Curculioninae such as micro Y chromosome and the typical “sphere-shape” of the sexual bivalent in prophase-I or after C-banding

Chromosome analysis using different staining techniques and fluorescent in situ hybridization in Cerithium vulgatum (Gastropoda: Cerithiidae)

In the present paper one population of the "large" subtidal mollusc Cerithium vulgatum Bruguiere, 1792 (Gastropoda: Cerithiidae) from the Northwestern coast of Sicily was investigated from a karyological point of view. The chromosome complement was Giemsa stained, conventionally karyotyped in 18 homomorphic chromosome pairs (10 bi-armed and 8 mono-armed), and subsequently analysed using silver, CMA3 and DAPI staining, and fluorescent in situ hybridization (FISH) with three repetitive DNA probes [ribosomal DNA (rDNA), (TTAGGG)n and (GATA)n]. FISH with the rDNA probe consistently mapped major ribosomal sites (18S-28S rDNA) in the terminal region of the short arms of one small sized mono-armed chromosome pair. Ribosomal DNA was transciptionally active as indicated by its preferential impregnation with silver nitrate (Ag-NOR) and did not contain a high amount of GC base pairs as suggested by the lack of a bright CMA3 fluorescence. The (TTAGGG)n telomeric probe was hybridized to the termini of nearly all chromosomes, thus demonstrating that, in C. vulgatum, this sequence has been conserved during the genomic evolution. The finding of the telomeric hexanucleotide in six species belonging to the three high taxa of Gastropoda supports the notion that this sequence is widespread within this class. The (GATA)n probe did not label any chromosome regions except for a minute terminal area of a single bivalent at pachytene stage

Evidence for male XO sex-chromosome system in Pentodon bidens punctatum (Coleoptera Scarabaeoidea: Scarabaeidae) with X-linked 18S-28S rDNA clusters

In scarab beetle species of the genus Pentodon, the lack of analysis of sex chromosomes in females along with the poor characterization of sex chromosomes in the males, prevented all previous investigations from conclusively stating sex determination system. In this study, somatic chromosomes from females and spermatogonial chromosomes from males of Pentodon bidens punctatum (Coleoptera: Scarabaeoidea: Scarabaeidae) from Sicily have been analyzed using non-differential Giemsa staining. Two modal numbers of chromosomes were obtained: 2n = 20 and 19 in females and males, respectively. This finding along with other karyological characteristics such as the occurrence of one unpaired, heterotypic chromosome at metaphase-I and two types of metaphase-II spreads in spermatocytes demonstrate that a XO male/XX female sex determining mechanism - quite unusual among Scarabaeoidea - operates in the species investigated here. Spermatocyte chromosomes have also been examined after a number of banding techniques and fluorescent in situ hybridization with ribosomal sequences as a probe (rDNA FISH). The results obtained showed that silver and CMA(3) staining were inadequate to localize the chromosome sites of nucleolus organizer regions (NORs) due to the over-all stainability of both constitutive heterochromatin and heterochromatin associated to the NORs. This suggests that heterochromatic DNA of P. b. punctatum is peculiar as compared with other types of heterochromatin studied so far in other invertebrate taxa. By rDNA FISH major ribosomal genes were mapped on the X chromosome

Evolutionary consequences of the past pandemics

In historical times epidemics and pandemics killed large proportions of the European population, with likely consequences for the human genome as a result of positive selection acting on protective alleles. Pathophysiological evidence has suggested, for example, that cystic fibrosis mutations may confer resistance to cholera or other chloride-secreting diarrhoeas, whereas a high incidence of the CCR5-Delta32 mutation, which nowadays plays a substantial role in immunity against HIV-I infection, has been proposed to have provided some immunity against plague (...............

The Neanderthal in the karst. First dating, morphometric, and paleogenetic data on the fossil skeleton from Altamura (Italy)

In 1993, a fossil hominin skeleton was discovered in the karst caves of Lamalunga, near Altamura, in southern Italy. Despite the fact that this specimen represents one of the most extraordinary hominin specimens ever found in Europe, for the last two decades our knowledge of it has been based purely on the documented on-site observations. Recently, the retrieval from the cave of a fragment of bone (part of the right scapula) allowed the first dating of the individual, the quantitative analysis of a diagnostic morphological feature, and a preliminary paleogenetic characterization of this hominin skeleton from Altamura. Overall, the results concur in indicating that it belongs to the hypodigm of Homo neanderthalensis, with some phenetic peculiarities that appear consistent with a chronology ranging from 172 +/- 15 ka to 130.1 +/- 1.9 ka. Thus, the skeleton from Altamura represents the most ancient Neanderthal from which endogenous DNA has ever been extracted