Membranes as a possible pacemaker of metabolism in cypriniform fish: does phylogeny matter?

The 'membrane pacemaker theory of metabolism' proposes that membranes set metabolic rate by modulating protein activity, and thus purports to explain membrane fatty acid allometry. This relationship has never been tested across species in ectotherms. After accounting for phylogeny, recent analyses have failed to support this theory based on correlations between muscle membrane composition and body mass across mammals.

Setting the pace of life: membrane composition of flight muscle varies with metabolic rate of hovering orchid bees.

Patterns of metabolic rate variation have been documented extensively in animals, but their functional basis remains elusive. The membrane pacemaker hypothesis proposes that the relative abundance of polyunsaturated fatty acids in membrane phospholipids sets the metabolic rate of organisms. Using species of tropical orchid bees spanning a 16-fold range in body size, we show that the flight muscles of smaller bees have more linoleate (%18 : 3) and stearate (%18 : 0), but less oleate (%18 : 1).

Stronger purifying selection against gene conversions in a pathogenic Saccharomyces cerevisiae strain.

Gene conversions most often have no selective impact, but some are selectively disadvantageous whereas others are selectively advantageous. Although gene conversions have been extensively studied in yeasts, very little is known about their selective impact in pathological yeasts. Here, we used the GENECONV software to compare the characteristics of candidate gene conversions found in a pathogenic strain (YJM789) and a nonpathogenic strain (S288c) of Saccharomyces cerevisiae.

The genetics of vitamin C loss in vertebrates.

Vitamin C (ascorbic acid) plays important roles as an anti-oxidant and in collagen synthesis. These important roles, and the relatively large amounts of vitamin C required daily, likely explain why most vertebrate species are able to synthesize this compound. Surprisingly, many species, such as teleost fishes, anthropoid primates, guinea pigs, as well as some bat and Passeriformes bird species, have lost the capacity to synthesize it.