PubMed Health⌕ Search

Biomedical subjects

G Procaccini

Publications and source records attributed to G Procaccini.

10 recordsLinked to original sources
PubMed2005

Assessing genetic diversity in clonal organisms: low diversity or low resolution? Combining power and cost efficiency in selecting markers.

The increasing use of molecular tools to study populations of clonal organisms leads us to question whether the low polymorphism found in many studies reflects limited genetic diversity in populations or the limitations of the markers used. Here we used microsatellite datasets for two sea grass species to provide a combinatory statistic, combined with a likelihood approach to estimate the probability of identical multilocus genotypes (MLGs) to be shared by distinct individuals, in order to ascertain the efficiency of the markers used and to optimize cost-efficiently the choice of markers to use for deriving unbiased estimates of genetic diversity. These results strongly indicate that conclusions from studies on clonal organisms derived using markers showing low polymorphism, including microsatellites, should be reassessed using appropriate polymorphic markers.

Alismatales↗
PubMed2005

Local genetic structure in a clonal dioecious angiosperm.

We used seven microsatellite loci to characterize genetic structure and clonal architecture at three different spatial scales (from meters to centimetres) of a Cymodocea nodosa population. C. nodosa exhibits both sexual reproduction and vegetative propagation by rhizome elongation. Seeds remain buried in the sediment nearby the mother plant in a dormant stage until germination. Seed dispersal potential is therefore expected to be extremely restricted. High clonal diversity (up to 67% of distinct genotypes) and a highly intermingled configuration of genets at different spatial scales were found. No significant differences in genetic structure were found among the three spatial scales, indicating that genetic diversity is evenly distributed along the meadow. Autocorrelation analyses of kinship estimates confirmed the absence of spatial clumping of genets at small spatial scale and the expectations of a very restricted seed dispersal (observed dispersal range 1-21 m) in this species.

DNA, Plant↗
PubMed2001

Spatial patterns of genetic diversity in Posidonia oceanica, an endemic Mediterranean seagrass.

Posidonia oceanica is an endemic seagrass species in the Mediterranean Sea. In order to assess levels of genetic structure in this species, the microsatellite polymorphism was analysed from meadows collected in several localities, along the coasts of the Tyrrhenian Sea (Mediterranean Sea). The existence of single population units and the recruitment of seedlings collected in some localities were investigated. Moreover, genetic structure at different spatial scales and biogeographic relationships among populations were also assessed. Our analysis showed the existence of clear patterns of genetic structure in P. oceanica in the area considered in the analysis. P. oceanica, in fact, is present in separate meadows that represent discrete populations, characterized by low genetic diversity. Comparable levels of genetic variability between mature meadows and seedlings were found. Patterns of genetic relatedness among populations seem to be in accord with direction of dominant current flux in the whole area, separating South Tyrrhenian from North Tyrrhenian populations. Moderate levels of gene flow between populations and genetic substructure within populations, together with the finding of the limited role of sexual reproduction in increasing genetic variability, should be a cause for concern for the persistence of this essential resource in the Mediterranean basin.

Genetic Variation↗
PubMed1994

Assessment of genetic diversity of seagrass populations using DNA fingerprinting: implications for population stability and management.

Populations of the temperate seagrass, Zostera marina L. (eelgrass), often exist as discontinuous beds in estuaries, harbors, and bays where they can reproduce sexually or vegetatively through clonal propagation. We examined the genetic structure of three geographically and morphologically distinct populations from central California (Elkhorn Slough, Tomales Bay, and Del Monte Beach), using multilocus restriction fragment length polymorphisms (DNA fingerprints). Within-population genetic similarity (Sw) values for the three eelgrass populations ranged from 0.44 to 0.68. The Tomales Bay population located in an undisturbed, littoral site possessed a within-population genetic similarity (Sw = 0.44) that was significantly lower than those of the other two populations. Cluster analysis identified genetic substructure in only the undisturbed subtidal population (Del Monte Beach). Between-population similarity values (Sb) for all pairwise comparisons ranged from 0.47 to 0.51. The three eelgrass populations show significantly less between locale genetic similarity than found within populations, indicating that gene flow is restricted between locales even though two of the populations are separated by only 30 km. The study demonstrates that (i) natural populations of Z. marina from both disturbed and undisturbed habitats possess high genetic diversity and are not primarily clonal, (ii) gene flow is restricted even between populations in close proximity, (iii) an intertidal population from a highly disturbed habital shows much lower genetic diversity than an intertidal population from an undisturbed site, and (iv) DNA fingerprinting techniques can be exploited to understand gene flow and population genetic structure in Z. marina, a widespread and ecologically important species, and as such are relevant to the management of this coastal resource.

Journal Article↗
PubMed1987

[Role of photon absorption densitometry of the bone in uremic osteodystrophy].

The aim of this investigation is to evaluate the role of bone photonic densitometry in uremic osteodystrophy. Bone mineral content (BMC) and bone density (BD) have been measured in 80 hemodialyzed patients by double photonic emission densitometry. Photonic densitometry shows an higher sensibility to quantitative changes in bone mineral content than metacarpal index (IM). Photonic densitometry is unable to differentiate osteoporosis from osteomalacia; this differential diagnosis can be obtained by radiological analysis: low BD and low IM means osteoporosis, low BD and resorptive changes in cortical bone means osteomalacia and/or hyperparathyroidism. Photonic densitometry is particularly suitable for uremic osteodystrophy follow-up because of its easy repetitiveness and innocuousness and for its close correlation with iPTH variations.

Adult↗
PubMedDate not supplied

[The factor of magnification in mammography].

The last generation of mammographic equipment allows mammography to be performed with direct magnification techniques, thanks to such technical features as microfocus, high focus-film distance, high-power generators. The authors compared the diagnostic yield of two different equipment sets, with 1.4x and 2x magnification respectively, and verified the utility of magnification radiography. A significant reduction was obtained in questionable diagnoses (42 to 18) in a group of 63 patients, with no evidence of substantial differences in the diagnostic yield of the images obtained with different magnification ratios. An objective analysis of the system resolution power privileges 2x magnification ratio, which however implies an increase in the average dose to the breast. The use of faster recording systems reduces the dose by 50%, though maintaining good image quality.

Breast Neoplasms↗
PubMedDate not supplied

[The use of the Daylight System in mammography].

It is widely known that Daylight film handling has yielded several benefits to diagnostic radiology, that is, reduction in exam duration, thus improving both efficiency and productivity; space saving in departments, by minimizing darkroom spaces; improved working conditions for the staff. This paper reports on the study of the application of a Daylight system to mammography. For this purpose, the authors used an X-ray unit (Senographe 500 T-CGR) and a Dupont Daylight unit, whose diagnostic yield was compared to that of "vacuum" and cassettes units. The results of our experience confirmed the well-known advantages DDS yields to diagnostic radiology. In particular, the use of Daylight rather than vacuum system allowed a considerable reduction in exam duration (10 to 2 minutes). Moreover, the new Dupont screen-film system allowed a reduction in average whole breast dose by about 28% if compared to the conventional recording system employed in our department. Mammograms with high contrast resolution, sensitivity, and good spatial resolution were thus obtained, as shown in the analysis of quality image. The Daylight system allowed a marked improvement to be made in efficiency, productivity, and organization, as well as a reduction in whole breast dose and high-quality mammographic images.

Evaluation Studies as Topic↗