Biomedical subjects

A Di Fiore

Publications and source records attributed to A Di Fiore.

5 recordsLinked to original sources

PubMed2004

Pattern and process in Amazon tree turnover, 1976-2001.

Previous work has shown that tree turnover, tree biomass and large liana densities have increased in mature tropical forest plots in the late twentieth century. These results point to a concerted shift in forest ecological processes that may already be having significant impacts on terrestrial carbon stocks, fluxes and biodiversity. However, the findings have proved controversial, partly because a rather limited number of permanent plots have been monitored for rather short periods. The aim of this paper is to characterize regional-scale patterns of 'tree turnover' (the rate with which trees die and recruit into a population) by using improved datasets now available for Amazonia that span the past 25 years. Specifically, we assess whether concerted changes in turnover are occurring, and if so whether they are general throughout the Amazon or restricted to one region or environmental zone. In addition, we ask whether they are driven by changes in recruitment, mortality or both. We find that: (i) trees 10 cm or more in diameter recruit and die twice as fast on the richer soils of southern and western Amazonia than on the poorer soils of eastern and central Amazonia; (ii) turnover rates have increased throughout Amazonia over the past two decades; (iii) mortality and recruitment rates have both increased significantly in every region and environmental zone, with the exception of mortality in eastern Amazonia; (iv) recruitment rates have consistently exceeded mortality rates; (v) absolute increases in recruitment and mortality rates are greatest in western Amazonian sites; and (vi) mortality appears to be lagging recruitment at regional scales. These spatial patterns and temporal trends are not caused by obvious artefacts in the data or the analyses. The trends cannot be directly driven by a mortality driver (such as increased drought or fragmentation-related death) because the biomass in these forests has simultaneously increased. Our findings therefore indicate that long-acting and widespread environmental changes are stimulating the growth and productivity of Amazon forests.

Biodiversity↗

PubMed2004

Non-HDL cholesterol predicts coronary heart disease in primary prevention: findings from an Italian 40-69 year-old cohort in general practice.

OBJECTS: Non-HDL cholesterol is now recommended as an index of risk associated with combined dyslipidemia, and it has also been found useful in predicting coronary heart disease (CHD) risk in patients with diabetes. We studied the association between known CHD risk factors, enclosed non-HDL cholesterol, and a "high CHD risk condition", i.e. a "5-years CHD risk >15%" in general practice. METHODS: We studied 4,085 40-69 year-old diabetic (no. 489) and non-diabetic (no. 3,596) individuals from an opportunistic cohort. Cross-sectional descriptive statistics, and age- and gender-adjusted multiple logistic exponential betas have been calculated. RESULTS: About 12% of the participants had diabetes. Age- and gender-adjusted comparison showed that all the study variables were significantly worse in diabetic vs. non-diabetic individuals (except cigarette smoking, total blood cholesterol and the ratio of total to HDL cholesterol). They had a mean "5-year CHD-risk" significantly higher than non-diabetic individuals (18.8+/-11.9% vs 7.5+/-6.9%, P<0.01), and a four-fold prevalence of "5-years CHD risk >15%" (55.4% vs 11.1%, P<0.01). As to diabetic individuals, the study variables associated to a "high CHD risk condition" were cigarette smoking, systolic blood pressure, and non-HDL blood cholesterol levels. As to non-diabetic individuals cigarette smoking, systolic blood pressure, and HDL (inversely) and non-HDL blood cholesterol levels were associated to a "high CHD risk condition". CONCLUSIONS: Non-HDL cholesterol--and cigarette smoking and systolic blood pressure--strongly predicted a "high CHD risk condition" both in diabetic and non-diabetic individuals.

Adult↗

PubMed2003

Crystal structure of the dimeric unswapped form of bovine seminal ribonuclease.

Bovine seminal ribonuclease is a unique case of protein dimorphism, since it exists in two dimeric forms, with different biological and kinetic behavior, which interconvert into one another through three-dimensional swapping. Here we report the crystal structure, at 2.2 A resolution, of the unswapped form of bovine seminal ribonuclease. Besides completing the structural definition of bovine seminal ribonuclease conformational dimorphism, this study provides the structural basis to explain the dependence of the enzyme cooperative effects on its swapping state.

Animals↗

PubMed1999

Universal linker and ligation procedures for construction of genomic DNA libraries enriched for microsatellites.

Microsatellite loci are highly informative genetic markers useful for population genetic studies, linkage mapping and parentage determination. Methods to identify novel microsatellite loci commonly use subtractive hybridization to enrich small-insert genomic libraries for repeat sequences. A critical step in enrichment is attachment of an oligonucleotide linker to genomic DNA fragments so that repeat-containing sequences can be recovered by PCR for cloning. Current linkers and ligation methods rely on single restriction enzymes to size-fraction genomic DNA and generate complementary ends. These restriction enzyme/linker combinations are often species-specific, give poor recovery of repeat-enriched DNA and yield library inserts that are not a broad sample of the genome. We have developed a blunt-end linker, named SNX for its restriction sites, that allows the use of combinations of restriction enzymes to digest the majority of genomic DNA into the 200-1000-bp range. SNX is attached to genomic DNA with a simultaneous ligation/restriction reaction that is highly efficient and improves recovery of sequences after subtractive hybridization. SNX can be used for microsatellite enrichment in any species, since ligation is independent of the restriction enzymes used to size-fraction genomic DNA. These methods improve current repeat-enrichment strategies, resulting in representative small-insert libraries with a very high proportion of positive clones.

Animals↗

PubMed1994

Evolution of social organization: a reappraisal for primates by using phylogenetic methods.

For many animal taxa, the extent to which phylogeny can account for the form of species' social systems has seldom been investigated formally. A quantitative phylogenetic analysis of social systems in the order Primates reveals that social organization may be strongly conserved in some lineages, even in the face of considerable ecological variability. This result has important implications for efforts to understand the evolution of animal societies and for attempts to reconstruct the social organization of early humans.

Animals↗