Climatic changes in western Spain

Possible interactions between climatic changes and vegetation during the present century in western Spain have been examined using a phytoclimatic model. Statistical analysis of meteorological data for the period 1901–1989 suggests a tendency towards a reduction in temperature differences with a negative tendency for maximums and variability and a positive tendency for minimum temperatures. Rainfall, number of rainy days and number of rainy sequences have shown positive tendencies since the beginning of the century. Phytoclimatic determination for the same period showed dominant mediterranean conditions until 1950. Around 1951, a point of inflection was detected, the more humid conditions thereafter becoming dominant, and more favorable to deciduous broad-leaf forests in transition towards mediterranean forests. In accordance with the results of other studies these data would indicate the changing tendencies detected could be affecting a large part of the northeastern Iberian Peninsula.     

Temperature coefficients of peptides dissolved in hexafluoroisopropanol monitor distortions of helices

Summary Temperature coefficients are widely used as an indication of solvent accessibility to amide protons. Low temperature coefficients are related to low accessibility and are often interpreted as evidence for intramolecular hydrogen bonding. Conformational shifts, i.e. the difference between chemical shifts of a particular residue in a structured and in a random-coil conformation, provide information on secondary structure. In particular, negative CH^α conformational shifts are often used to delineate the extent of helical stretches. NH conformational shifts show large oscillations within a helix that have been interpreted as the result of helix distortions affecting hydrogen bond lengths. In the ocurse of the study of differnet peptides that adopt a helical structure in the presence of the structure-inducing solvent hexafluoroisopropanol (HFIP), we have found a strong correlation between temperature coefficients and amide conformational shifts. However, contrary to the initial expectations, lower temperature coefficients were associated to amide protons involved in longer, and presumably weaker, hydrogen bonds. The correlation can be explained, however, assuming that, in helical peptides dissolved in HFIP, temperature affects the chemical shift of amide protons mainly by changing the average length of intramolecular hydrogen bonds and changes in solvent accessibility play only a secondary role under these experimental conditions. The pattern of temperature coefficients in helical peptides can therefore be used to identify short or long hydragen bonds causing bending of the helix axis.     

Mitochondrial DNA and Y‐chromosome diversity in East Adriatic sheep

Variation in mitochondrial DNA (mtDNA) and Y‐chromosome haplotypes was analysed in nine domestic sheep breeds (159 rams) and 21 mouflon ( Ovis musimon) sampled in the East Adriatic. Mitochondrial DNA analyses revealed a high frequency of type B haplotypes, predominantly in European breeds, and a very low frequency of type A haplotypes, which are more frequent in some Asian breeds. Mitochondrial haplotype Hmt‐3 was the most frequent (26.4%), and 37.1%, 20.8% and 7.6% of rams had haplotypes one, two and three mutations remote from Hmt‐3 respectively. In contrast, Y‐chromosome analyses revealed extraordinary paternal allelic richness: HY‐6, 89.3%; HY‐8, 5.0%; HY‐18, 3.1%; HY‐7, 1.3%; and HY‐5, 1.3%. In fact, the number of haplotypes observed is comparable to the number found in Turkish breeds and greater than the number found in European breeds so far. Haplotype HY‐18 (A‐oY1/135‐SRYM18), identified here for the first time, provides a link between the haplotype HY‐12 (A‐oY1/139‐SRYM18) found in a few rams in Turkey and haplotype HY‐9 (A‐oY1/131‐SRYM18) found in one ram in Ethiopia. All mouflons had type B mtDNA haplotypes, including the private haplotype (Hmt‐55), and all were paternally monomorphic for haplotype HY‐6. Our data support a quite homogeneous maternal origin of East Adriatic sheep, which is a characteristic of European breeds. At the same time, the high number of haplotypes found was surprising and intriguing, and it begs for further analysis. Simultaneous analysis of mtDNA and Y‐chromosome information allowed us to detect a large discrepancy between maternal and paternal lineages in some populations. This is most likely the result of breeder efforts to ‘upgrade’ local populations using rams with different paternal origins.