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M Gatti

Publications and source records attributed to M Gatti.

At least 145 records · Page 8Linked to original sources
PubMed1976

Characterization of Drosophila heterochromatin. I. Staining and decondensation with Hoechst 33258 and quinacrine.

A number of preliminary experiments have shown that the fluorescence pattern of Hoechst 33258, as opposed to that of quinacrine, varies with the concentration of dye. The metaphase chromosomes of D. melanogaster, D. simulans, D. virilis, D. texana, D. hydei and D. ezoana have therefore been stained with two concentrations of H 33258 (0.05 and 0.5 mug/ml in phosphate buffer at pH 7) and with a single concentration of quinacrine (0.5% in absolute alcohol). The three fluorescence patterns so obtained were shown to be somewhat different in some of the species and the coincide in others. All three stainings gave an excellent longitudinal differentiation of heterochromatin while euchromatin fluoresced homogeneously. Living ganglion cells of the six species mentioned above were treated with quinacrine and H 33258. Quinacrine induced a generalized lengthening and swelling of the chromosomes and H 33258 the decondensation of specific heterochromatic regions. A correlation of the base composition of the satellite DNAs contained in the heterochromatin of the species studied with the relative fluorescence and decondensation patterns showed that: 1) the extremely fluorochrome bright areas and those decondensed are present only in species containing AT rich satellite DNA; 2) the opposite is not true since some AT-rich satellite DNAs are neither fluorochrome bright nor decondensed; 3) there is no good correspondence between Hoechst bright areas and the decondensed ones. AT richness therefore appears to be a necessary but not sufficient condition both for bright fluorescence and decondensation. Some cytological evidence suggests that similarly AT rich satellite DNAs respond differently in fluorescence and decondensation because they are bound to different chromosomal proteins. A combination of the results of fluorescence and decondensation revealed at least 14 types of heterochromatin; 4-7 of which are simultaneously present in the same species. Since closely related species (i.e. D. melanogaster and D. simulans; D. virilis and D. texana) show marked differences in the heterochromatic types they contain, it can be suggested that within the genus Drosophila qualitative variations of heterochromatin have played an important role in speciation.

Animals↗
PubMed1976

Characterization of Drosophila heterochromatin. II. C- and N-banding.

The C- and N-banding patterns of D. melanogaster, D. simulans, D. virilis, D. texana, D. ezoana and D. hydei were studied in comparison with quinacrine and Hoechst banding patterns. In all these Drosophila species the C bands correspond to the heterochromatin as revealed by the positive heteropycnosis in the prometaphase chromosomes. The N bands have the following characteristics: 1) they are always localized on the heterochromatin and generally do not correspond to the C bands; 2) they do not correspond to the nucleolar organizing regions; 3) they are inversely correlated with fluorescence, i.e., they correspond to regions which are scarcely, if at all, fluorescent after Hoechst 33258 or quinacrine staining; 4) they are localized both on regions containing AT rich satellite DNA and on those containing GC rich satellite DNA.

Animals↗
PubMed1976

X-ray induction of chromatid interchanges is somatic cells of Drosophila melanogaster: variations through the cell cycle of the pattern of rejoining.

The relative frequencies of X-ray-induced symmetrical and asymmetrical chromatid interchanges were analysed as a function of the cell cycle in somatic cells of Drosophila melanogaster. In exchanges between autosomes, during the S phase, a clear prevalence of asymmetrical rejoining was observed. Later, this prevalence became reduced as the cell approached mitosis. On the other hand, in the exchanges between X-chromosomes in the females there were no significant variations in the type of rejoining through the cell cycle, there being a slight but consistent preference for symmetrical rejoining. These data are discussed in relation to the hypothesis proposed by Olivieri et al. [12] on the organization of the chromosomal sub-units in the interphase nucleus.

Animals↗
PubMed1976

Effects of Hoechst 33258 on human leukocytes in vitro.

The benzimidazole derivative Hoechst 33258 was added at various concentrations to human leukocyte cultures. After 16 or 24 h of treatment, with concentrations equal to or greater than 100 mug/ml of Hoechst 33258, a number of chromosomes showed regions in which the chromatin was undercontracted. The centromeric regions of chromosome 1 and, more rarely, of chromosomes 3 and 9 appeared to be decondensed. Short decondensed regions were also present on the long arms of chromosomes 1 and 2. The possible nature of these regions is discussed.

Benzimidazoles↗
PubMed1975

Chemical induction of chromosome aberrations in somatic cells of Drosophila melanogaster.

Third instar larvae of the Oregon R stock were treated for 25 or 30 min with vapour of methyl methanesulphonate (MMS). At various times after the treatment (4, 8 and 12 h), microscope specimens of the nerve ganglia were prepared. At all the times of fixation, only aberrations of a chromatid type were found, but with different frequencies in the two sexes. The females were about 3 times more sensitive than the males to MMS. An analysis of the distribution of the breaks between and within chromosomes showed that they were not localized at random but were clustered in the heterochromatic centromere regions of the X chromosome and the autosomes. The Y chromosome, although entirely heterochromatic, on the other hand, was highly resistant to MMS. However, this phenomenon had only a very weak effect upon the variation with sex of MMS-induced chromosome damage. Among the aberrations induced, although interchanges were normally present, neither intra-exchanges nor triradials were found. In the interchanges, there was a greater tendency for the homologous chromosomes to be involved, and these rejoined symmetrically. The above results are discussed in relation to data previously obtained with X-rays.

Animals↗
PubMed1974

Analysis of the chromosome aberrations induced by x-rays in somatic cells of Drosophila melanogaster.

A technique has been perfected for enabling good microscope preparations to be obtained from the larval ganglia of Drosophila melanogaster. This system was then tested with X-rays and an extensive series of data was obtained on the chromosome aberrations induced in the various stages of the cell cycle.-The analysis of the results obtained offers the following points of interest: (1) There exists a difference in radio-sensitivity between the two sexes. The females constantly display a greater frequency of both chromosome and chromatid aberrations. They also display a greater frequency of spontaneous aberrations. (2) In both sexes the overall chromosome damage is greater in cells irradiated in stages G(2) and G(1). These two peaks of greater radiosensitivity are produced by a high frequency of terminal deletions and chromatid exchanges and by a high frequency of dicentrics, respectively. (3) The aberrations are not distributed at random among the various chromosomes. On the average, the Y chromosome is found to be more resistant and the breaks are preferentially localized in the pericentromeric heterochromatin of the X chromosome and of the autosomes. (4) Somatic pairing influences the frequency and type of the chromosome aberrations induced. In this system, such an arrangement of the chromosomes results in a high frequency of exchanges and dicentrics between homologous chromosomes and a low frequency of scorable translocations. Moreover, somatic pairing, probably by preventing the formation of looped regions in the interphase chromosomes, results in the almost total absence of intrachanges at both chromosome and chromatid level.

Animals↗
PubMedDate not supplied

Familial incidence of twinning.

The frequency of twinning among women who have already borne twins, the 'repeat frequency', is significantly higher than in the general population. Individual propensity is not necessarily genetic in origin, but pedigree studies (for reviews see refs 1, 2) confirm that twinning is a family trait. Studies based on archives restrict this conclusion to dizygotic (DZ) twinning and the maternal side, while studies based on interviews of relatives of twins find monozygotic (MZ) twinning and the paternal side also to be involved. However, interview studies can overestimate, while archive studies can underestimate, the real frequency of twinning. We have now analysed the incidence of twinning in the families of 950 zygosity-determined, unselected twin pairs under complete ascertainment. Our results indicate that a propensity to MZ twinning, as well as one to DZ twinning, can be inherited through the maternal line, and that the two mechanisms of twinning might be related. We have also found a paternal role in DZ, but not in MZ twinning.

Female↗
PubMedDate not supplied

[Prognostic factors in the treatment of advanced cervical cancer. A retrospective study].

BACKGROUND: The value of prognostic factors in patients with advanced cervix carcinoma treated by radiotherapy was assessed in a retrospective study. METHODS: From January 1977 through December 1990, 261 patients (average age 60 years) were treated at the Radiotherapy Department of the University of Turin. Distribution by stage was: 142 T2b (54%), 8 T3a (3%), 98 T3b (38%) and 13 T4 (5%). 83% of the patients underwent radiotherapy alone; the total dose was 45-88 Gy in 91 patients (42%) with poor clinical conditions, 60-75 Gy in 121 (56%) and 75-80 Gy in 5 cases. 17% of the patients was treated by surgery combined with radiotherapy. The median follow-up was 50 months (minimum 2, maximum 177 months). RESULTS: The 5-year NED survival and local control were 42% (52% for T2b, 33% for T3 and 15% for T4). The severe (G3-G4) complication rate was very low (1.9%). CONCLUSION: In our series, the prognostic factors which significantly influenced survival in the uni-variate analysis were: advanced T stage, contemporary infiltration of parametrium and vagina, nodal status, non squamous neoplasm, younger age and the absence of brachytherapy in the radiotherapy alone protocol.

Adult↗