Carnitine is indispensable for energy metabolism, since it enables activated fatty acids to enter the mitochondria, where they are broken down via beta-oxidation. Carnitine is probably present in all animal species, and in numerous micro-organisms and plants. In mammals, carnitine homoeostasis is maintained by endogenous synthesis, absorption from dietary sources and efficient tubular reabsorpt...

Brucella infections have recently been recognized in seals, sea lions, walruses, dolphins, porpoises, whales and an otter. This organism appears to be widespread in marine mammals, and has probably been endemic in these populations for a long time. The clinical significance is uncertain. A few infections have been associated with placentitis/abortions, neonatal mortality, meningoencephalitis, a...

Many organisms show major chromosomal differences between sexes. In mammals, females have two copies of a large, gene-rich chromosome, the X, whereas males have one X and a small, gene-poor Y. The imbalance in expression of several hundred genes is lethal if not dealt with by dosage compensation. The male-female difference is addressed by silencing of genes on one female X early in development....

Although Darwin identified the evolutionary significance of competition between males in the context of reproduction, it is only in the past few decades that we have begun to appreciate the importance of competition at the gametic level. Sperm competition, defined as competition between the sperm of two or more males for fertilization of the same set of ova, is now recognised as a key selective...

It is often assumed that navigation implies the use, by animals, of landmarks indicating the location of the goal. However, many animals (including humans) are able to return to the starting point of a journey, or to other goal sites, by relying on self-motion cues only. This process is known as path integration, and it allows an agent to calculate a route without making use of landmarks. We re...

which tend to capitalize on similarity rather than change. Time ranges of biologic rhythms are explored and an enormous variation is evident ranging from fractions of a second within an individual to millions of years in an evolutionary scale. The influence and interplay of exogenous and endogenous factors in such rhythms are discussed and abnormalities of rhythms are considered to be of fundam...

The enzymes involved in the initial degradative steps of lysine metabolism, lysine-2-oxoglutarate reductase and saccharopine dehydrogenase, were studied and their activities in different mammals compared. Values obtained in human, rat, pig, dog, cat, ox and sheep liver indicated that in vitro, appreciable degradation of lysine to saccharopine (4-6nmol/min per mg of protein) occurred. The specif...

In contrast to the biallelic expression of most genes, expression of imprinted genes is monoallelic and depends on the sex of the transmitting parents. In humans it has been implicated in some developmental failures, neurodevelopmental and neurobehavioral disorders (such as Prader-Willi/Angelman, Silver-Russel or Beckwith-Wiedemann syndromes). The aim of this review is to present the phenomenon...

BACKGROUND Several organs such as the skin and liver have a great capacity for regeneration. However, many approaches only delay the progression of end-stage kidney disease and do not achieve efficient long-term stabilization, let alone regeneration. SUMMARY In mammals, the kidney has an innate but limited capacity for regeneration which can only modify the nephron structure and function but ...

We see then that here, just as in the case of diatomic molecules, the permanent moment of the molecules and the part of the dielectric constant due to it are related by Debye's equation derived on the classical theory provided the temperature is sufficiently high. As regards the behavior of the bands emitted by dipole-molecules of the kind considered in an electric field, there should be a line...