Heterospecific hybrids often suffer from a lowered fitness relative to parental species. Contextdependent intrinsic costs of hybridization are partially due to a malfunction in cell biochemical machinery that affects metabolic rates at the organismal level. This study examines whether heterospecific hybridization influences the metabolic costs of maintenance in F1 hybrids between closely related newts, Triturus carnifex and T. dobrogicus. When controlled for body size, oxygen consumption in hybrid newts was 59-76 % higher than in the parental species. This suggests that high standard metabolic rates in hybrids may contribute to thecosts of hybridization in newts.
Aging is a process drawing attention of many researchers, and at present many theories exists, which try to explain this chain of inevitable events leading to death of organism. In this article we focused our attention on a theory explaining the degenerative changes occurring during aging by the effect of oxygen free radicals. These highly reactive radicals are produced during oxidative phosphorylation in mitochondria. All cellular components appear to be sensitive to oxygen-radical damage. Lipids, proteins and nucleic acids are probably the most susceptible to this injury. Lipoperoxidation of lipids together with cross-linking of proteins with phospholipids and nucleic acids caused changes in membrane fluidity. Mitochondrial DNA coding several subunits of respiratory chain enzymes can be also damaged by these radicals. All these changes together have negative impact on mitochondrial metabolism resulting progressive decrease of the efficiency of oxidative phosphorylation and thus of the whole organism.
Since the beginning of the 19th century, the comparative and ontogenetic branches of developmental physiology were cultivated in our country. Evidence was given that development of the gastrointestinal tract in tadpoles is dependent on the quality of proteins in their food. A complete metamorphosis of Amblystoma mexicanum, was entirely accomplished by feeding with powderized thyroid gland. The definition and chronological delimitation of both the suckling and weaning period in experimental animals opened the investigation of the effect of disturbance of the natural environment caused by premature weaning on the ensuing development of an individual. A new term was coined "late effects of early adaptations". Analysis was provided by impressive research of the development of energetic metabolism and development of gastrointestinal tract functions, water and electrolyte exchange and endocrine functions including the role of the pineal gland in control of circadian rhythms (12 references).