Giuseppe Ardito

Cell kinetics and sister-chromatid-exchange frequency in human lymphocytes

Repeated cultures from 5 healthy donors were set up in 3 tissue-culture media: TC109, TC199 and TC1640. For each donor, 3 blood samples were taken at 1-week intervals, making a total of 5 x 3 x 3 = 45 cultures. Our results show a large variability in the individual SCE base-line frequency. This variability can be partly attributed to the different tissue-culture media or to the donors themselves. Our results, however, stress the importance of the proliferating rate of the culture in determining the SCE frequency.

Cytogenetic monitoring of hospital workers exposed to low-level ionizing radiation

In the present study the cytogenetic effects in hospital workers exposed to low-level radiation were evaluated. Samples of peripheral blood were collected from 63 subjects working in radiodiagnostics and from 30 subjects, working in the same hospitals, who were used as controls. A higher number of cells with chromosome-type aberrations (CA) was observed in the exposed workers vs. the controls and the difference was statistically significant (p less than 0.05). No correlation was, on the contrary, found between CA and years of exposure. A significant difference was observed in the incidence of cells with CA between smokers and non-smokers, but in the control group only. In contrast, in the workers exposed to ionizing radiation, the frequency of cells with CA was very similar in smokers and non-smokers.

Phylogenetic Relationships Among Malagasy Lemurs as Revealed by Mitochondrial DNA Sequence Analysis

Systematics and evolution of Malagasy lemurs has been analyzed using morphological characters, fossil evidence, ecological/ethological data, and chromosomal banding patterns. Recent developments in DNA technology have provided evolutionary biologists with additional and powerful tools for making phylogenetic inference. In the last years several studies concerning highly repeated DNA sequences (hrDNA) provided new insights about the systematic relationships among the different species of Lemuridae and Cheirogaleidae.Here, a reconstruction of molecular phylogeny of extant Malagasy lemurs based on the comparison of cytochrome-b mitochondrial DNA sequences is presented. With the Polymerase Chain Reaction (PCR) and direct sequencing of amplified DNA fragments, both the phylogenetic range and resolving power of comparative analysis can be extended. These techniques allow to gather sequence data useful to evaluate the pattern of molecular evolution offering opportunities for phylogenetic purposes.A 290-bp fragment of cytochrome-b gene has been amplified and sequenced from the following species:Tupaia glis, Galago alleni, Daubentonia madagascariensis, Indri indri, Varecia variegata, Eulemur fulvus, Eulemur coronatus, Eulemur rubriventer, Eulemur mongoz, Eulemur macaco, Lemur catta, andHapalemur griseus griseus.The phylogenetic trees obtained show the relationships among the Eulemur species and confirm the karyological and hrDNA results of a separated clade forL. catta/Hapalemur. The separation ofVarecia variegata from the other genus of the family Lemuridae is discussed.

Mitochondrial Sequences as Indicators of Generic Classification in Bush Babies

Systematic relationships among the African bush babies are not well understood. Various generic designations are currently in use. Some authors refer all species to a single genus (Galago), while others recognize ≤4 genera. Phylogenetic reconstructions based on morphology, karyology, allozymes and vocal repertoires have generated inconsistent hypotheses of relationship. We analyzed partial sequences of three mitochondrial genes (270 bp from cytochrome b, 387 bp from 12S rRNA, and 241 bp from 16S rRNA, total 898 bp) to resolve some uncertainties. We sampled taxa from each of three genera: Galagoides alleni, G. demidoff and G. zanzibaricus; Galago senegalensis, G. gallarum and G. moholi; and Otolemur crassicaudatus and O. garnettii. Outgroup taxa were Asian lorises: Nycticebus coucang and Loris tardigradus. We analyzed sequences separately and in combination, and modeled phylogenies using maximum parsimony, weighted parsimony, neighbor-joining and maximum-likelihood. We obtained some variation in phylogenetic inference depending on sequence and analytical method, but the results also gave strong phylogenetic signals. The lesser bush babies invariably formed a clade, showing evidence of very recent radiation. The greater bush babies also formed a clade, marked by somewhat greater interspecific genetic distances, which was allied with Galagoides alleni in most instances. Galagoides demidoff and G. zanzibaricus are not closely related, though both diverged early in the history of the group. A genus comprising Galagoides alleni, G. demidoff and G. zanzibaricus is not supported by our data. The most likely alliance for Galagoides alleni is within the genus Otolemur. Of the three partial sequences employed in the study, 16S rRNA gave the most consistent results, while cytochrome b was least informative.

Frequencies of oral pathologies in a sample of 767 non-human primates

In this work 767 skulls of both wild caught and captive non-human primates were studied and the following characteristics were analyzed: frequency of caries and osteolytic phenomena, presence of apical or radicular cysts, degree of bone atrophy and parodontal tissue alterations, neoplasies, supernumerary teeth, and cusps. Caries and osteolytic phenomena were more frequent in captive animals because of their “anthropic” diet, while frequency of dental fractures was higher in wild primates because of their higher environmental stress. The most frequent pathologies observed in non-human primates were tartar, parodontopathies, and condylar wear, while caries and osteolytic phenomena were minimal. Condylar wear was very frequent but not very marked and possibly due to “physiological” responses and not, as in humans, to a force unbalance which occurs in masticatory dynamics of the temporomandibular joint.

No correlation between chimerism and fertility inCallithrix jacchus (Callithricidae, Primates)

In this study, 40 individuals ofCallithrix jacchus were analyzed in order to investigate the frequency of chimerism and to determine whether the fertility of the colony was in any way affected by chimerism.In the individuals considered the degree of chimerism ranged from 2% to 97% and no correlation was established between the degree of chimerism and fertility of the individuals. Many “good breeders” were chimeric and the best female breeders displayed 84% and 97% chimerism respectively.

Sister-chromatid exchange rates in XX and XY cells of ten chimeric Callithrix jacchus individuals.

In order to ascertain whether or not sister-chromatid exchange (SCE) differs in relation to sex, SCE rates in XX and XY cells from 10 specimens of marmoset (Callithrix jacchus) were examined. The choice of this primate is particularly suitable for three reasons: most individuals have a chimeric constitution, the X chromosome is quite large and the Y chromosome is particularly small. Therefore, the influence of possible differences in their exposure to the external environment can be eliminated. The results obtained did not reveal any significant difference between SCE rates in male and female cells in any of the examined individuals.

Baseline and mitomycin C(MMC)-induced sister-chromatid exchanges in XX and XY cells of Callithrix jacchus chimeric twins

Lymphocytes from chimeric individuals of the species Callithrix jacchus (Primates) were examined to evaluate differences in the frequency of sister chromatid exchanges (SCE) between XX and XY cells. The aim was to discover whether SCE differ according to genetic sex and whether XX and XY cells show a different sensitivity to SCE inducing agents. This experimental model has enabled us to eliminate the possible differences caused by environmental factors. The results obtained do not reveal significant differences between male and female cells, in either the baseline SCE frequency or that induced by mitomycin C at concentrations of 0.01 and 0.03 microgram/ml. No significant differences were observed in the distribution of high SCE frequency cells (HFC), even if it is possible to observe a higher level of exchanges in XX cells in each trial. With regard to the phenotypic sex, there appears to be a trend towards slightly higher SCE rates in females, even if results are not statistically significant.

Frequency and non random distribution of silver-staining NORs on acrocentric chromosomes from neonate and adult human lymphocytes

The NORs frequency in a group of newborns and adults was determined by the gelatine silver staining technique. A higher number of Ag-NORs (χ2 test, p<0.01) was found in adults than in newborns. The lack of correlation between cell proliferating rate index (PRI) and frequency of Ag-NORs let us suppose that the decrease of Ag-positive NORs in neonates could probably be due to factors different from cell kinetics.A non random distribution of Ag-NORs on the acrocentric chromosomes was also demonstrated: chromosome 21, in particular, showed the highest frequency, while chromosome 15, the lowest.

Comparative analysis of DNA restriction patterns ofHomo, Pan troglodytes eMacaca fascicularis after hybridization with human genomic probes: β1-Integrin, pAW101 anderb-B2

In the present work, Eco RI digested genomic DNA fromMacaca fascicularis, Pan troglodytes and Man were hybridized with three human probes (β1-Integrin, pAW101; anderb-B2) and the relative restriction patterns are presented.After hybridization with theβ1-Integrin probe it was possible to demonstrate a high intraspecific variability in the Macaca and Pan sample, while the other two probes utilized didn’t show any difference among the different species considered.In order to calculate the phylogenetic distances, some mathematical models are available, however severe limits exists at present in their application.