No abstract

Limited research findings up-to-date with a few amphibian models do not permit a generalisation of ageing phenomena in the class Amphibia. Short-lived species of amphibians show gradual senescence comparable to the pattern seen in laboratory mammals. Long-lived species (mostly urodeles) continue to grow throughout life and are believed to exhibit very slow or negligible senescence which is unobtrusive. In a few species with gradual senescence, there is some evidence of an increase in mortality rate and a decrease in growth rate with advancing age. Increase in cross-linking of collagen, accumulation of age pigments (lipofuscin and melanin), decrease in metabolism and loss of immunocompetence are ageing phenomena common to both amphibians and mammals. On the other hand, persistence of neurogenesis and myogenesis, continuance of oogenesis beyond adult life and polyphyodonty are some of the features peculiar to ageing in amphibians. More authenticated reports are needed to fill up the gaps in our knowledge on amphibian senescence.

No abstract

No abstract

Thermal inactivation of hepatic succinic dehydrogenase (SDH) (EC 1.3.99.1) at 51 ± 1 °C resulted in a higher degree of inhibition in middle-aged and old than in young lizards. The oxaloacetate inhibition of SDH activity and that of oxygen uptake of liver homogenates after 1 h of incubation also showed a similar pattern of age dependency. With increase in time interval (from 15 to 60 min) the young and to some extent the middle-aged lizards showed a partial recovery from inhibition of oxygen consumption of liver homogenates, but not the old animals.