Biogeographical diversity is central to the trophic ecology of predators. Understanding the biogeographical trophic patterns of generalist predators, such as the red fox Vulpes vulpes, is particularly challenging because of their wide distributions, broad trophic spectra and high ecological plasticity, which often generate conflicts with humans. We reviewed 55 studies from the Iberian Peninsula concerning the diet of the red fox to describe its trophic patterns from a biogeographical perspective. We considered the frequency of occurrence of seven food groups and characterized each study site according to environmental variables. We tested relationships between geographical variables and each food group independently, and assessed the consumption of lagomorphs in relation to the other food groups. We also tested the relationships between trophic diversity, the main food groups, latitude and altitude, and finally investigated changes in the consumption of all food groups in relation to habitat type and seasonality. We found a latitudinal pattern in the diet of the red fox, which was characterized by a greater consumption of lagomorphs and invertebrates in southern areas, and a higher intake of small mammals and fruits/seeds in northern regions. Additionally, the consumption of invertebrates increased from east to west, while fruit/seed consumption increased from west to east. Consumption of lagomorphs decreased, and of small mammals increased, with altitude. Trophic diversity was not associated with geographical variables. The intake of lagomorphs and small mammals was greatest in Mediterranean scrub and forest, respectively. Reptiles and invertebrates were consumed mostly during summer; fruits/seeds in autumn. Iberian red foxes show variation in their feeding habits associated with environmental variables, which are in turn associated with the availability of their main prey. Foxes select rabbits where they are abundant, and feed on small mammals and fruits/seeds where lagomorphs are scarce.
Coenzyme Q(10) (CoQ(10)) deficiency has been associated with an increasing number of clinical phenotypes that respond to CoQ(10) supplementation. In two siblings with encephalomyopathy, nephropathy and severe CoQ(10) deficiency, a homozygous mutation was identified in the CoQ(10) biosynthesis gene COQ2, encoding polyprenyl-pHB transferase. To confirm the pathogenicity of this mutation, we have demonstrated that human wild-type, but not mutant COQ2, functionally complements COQ2 defective yeast. In addition, an equivalent mutation introduced in the yeast COQ2 gene also decreases both CoQ(6) concentration and growth in respiratory-chain dependent medium. Polyprenyl-pHB transferase activity was 33-45% of controls in COQ2 mutant fibroblasts. CoQ-dependent mitochondrial complexes activities were restored in deficient fibroblasts by CoQ(10) supplementation, and growth rate was restored in these cells by either CoQ(10) or uridine supplementation. This work is the first direct demonstration of the pathogenicity of a COQ2 mutation involved in human disease, and establishes yeast as a useful model to study human CoQ(10) deficiency. Moreover, we demonstrate that CoQ(10) deficiency in addition to the bioenergetics defect also impairs de novo pyrimidine synthesis, which may contribute to the pathogenesis of the disease.
Recent studies show that the availability of prey in¯uences the ecology of otters by regulating breeding, carrying capacity and mortality. Mediterranean habitats experience extreme seasonal variation in water ow ± a stress period can occur in summer when water¯ows and levels are low with long periods of drought, while torrential¯oods usually occur in autumn and spring. Reservoirs can affect this situation by further in¯uencing water¯ow regimes and acting as a barrier. Our data show the close relationship between the amount of food (®sh) available to otters and their use of a stretch of water and the otter density there. The adjustment of the number of individuals (and carrying capacity) in an area can be seen from their mortality, a decrease in their reproductive success, or migration. Our results are consistent with the hypothesis that otters are food-limited. Torrential rains, summer droughts and dams for water management have repercussions for otter populations in as much as they affect their prey-species. Barbels Barbus spp. and, secondarily, nases Chondrostoma spp. are shown to be important to otter ecology and breeding in Mediterranean Iberian rivers. The conservation and management of the otter in these habitats must not ignore the management of food sources. In order not to affect otter populations, the effect of the reservoirs and their dams also must be considered. The release and cessation of¯oodwater from reservoirs must be progressive and mimic more closely the¯ow regime of natural rivers.
Coenzyme Q is a lipid molecule required for respiration and antioxidant protection. Q biosynthesis in Saccharomyces cerevisiae requires nine proteins (Coq1p-Coq9p). We demonstrate in this study that Q levels are modulated during growth by its conversion from demethoxy-Q (DMQ), a late intermediate. Similar conversion was produced when cells were subjected to oxidative stress conditions. Changes in Q 6 /DMQ 6 ratio were accompanied by changes in COQ7 gene mRNA levels encoding the protein responsible for the DMQ hydroxylation, the penultimate step in Q biosynthesis pathway. Yeast coq null mutant failed to accumulate any Q late biosynthetic intermediate. However, in coq7 mutants the addition of exogenous Q produces the DMQ synthesis. Similar effect was produced by over-expressing ABC1/COQ8. These results support the existence of a biosynthetic complex that allows the DMQ 6 accumulation and suggest that Coq7p is a control point for the Q biosynthesis regulation in yeast.
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