B.K. Patnaik

Age-determination in the tropical agamid garden lizard, Calotes versicolor (Daudin), based on bone histology

Abstract Male garden lizards showed excellent positive correlations between body weight and S-V length; body weight and tail girth; and body weight and gonad weight, suggesting the utility of these parameters as indirect markers of chronological age. However, the reliability of such morphometric data needed rapport from a more accurate method of bone histology based on the techniques of ‘skeletochronology’. Cross-sections of diaphyses of the humerus and femur of bones lizards of a complete age series revealed that while in young, immature and sexually mature lizards who have not yet completed a year in the wild there are no distinct annulations, the representative of fully mature and old lizards exhibited an alternation of thinner and thicker annulations arranged concentrically. Cross-sections of phalanges of old lizards also showed agreement with the annulations in diaphysis. The thinner annulations (LAC), corresponding with the period of slow growth, as in temperate species of lizards, were haemotoxylinophilic (chromophilic) and showed yearly growth patterns, their number representing the age of the lizards in years. Transverse sections of humeral epiphysis of old lizards exhibited, in contrast to the cartilaginous nature of young immature lizards, an almost complete calcification and bony union, suggesting a limitation of further growth. Thus, based on the recurrence of growth lines (LAC) in the diaphysis of long bones and in the phalanges, it is possible as in temperate species of lizards and turtles, to determine accurately the age of individuals belonging to a wild population of tropical lizards.

Alterations in the RNA, protein and free amino acid level of the liver of the garden lizard, calotes versicolor, during aging and partial hepatectomy

Abstract The relative RNA content (mg/g wet wt.) in the liver of Calotes versicolor rises till the lizards weight about 15 g and then declines with increasing age. Total RNA (mg/whole liver) reaches the peak at 32–38 g of bodyweight and remains constant thereafter. The protein concentration (mg/g wet wt.) increases more rapidly up to 48 g of bodyweight and then slowly increases during the later half of the lifespan. The total protein (mg/whole liver) also shows the same trend. The specific free amino acid level (mg/g wet wt.) shows a decline till the lizards weigh 32–38 g and thereafter remains at a constant level. Total free amino acid pool (mg/ whole liver) increases more significantly up to 35–38 g bodyweight followed by a slow rise. Partial hepatectomy leads to an increase in RNA, Protein and free amino acid content of the liver at 4 hr after operation followed by a decrease at 24 hr. The changes in protein and free amino acid content were more significant in younger lizards than the older ones.

Collagen characteristics of skin and muscle of the ageing teleost, Ophiocephalus punctatus

Abstract The age-related trends of solubility of skin and muscle collagen in salt and acid and the soluble/insoluble collagen ratio were traced in the fresh water murrel, Ophiocephalus punctatus of both sexes. Salt solubility and the salt soluble/salt insoluble collagen ratio in both the tissues of either sex reached peak levels during maturity and declined thereafter. Unlike mammalian skin the acid solubility and the acid soluble/acid insoluble collagen ratio of fish skin of either sex showed a positive correlation with advancing age. On the other hand, the same parameters of muscle collagen declined with age, suggesting a common pattern of ageing between fish and mammal.

Studies on the connective tissue of reptiles—I. Age changes in collagen and water contents of bone and hyoid cartilage of male garden lizard

Abstract The solubility of collagen in long bones and hyoid cartilage of the garden lizard, Calotes versicolor , was tested by extraction in 0·45 m NaCl and 0·45 m Acetic acid. The age related decline in the solubility was evident in both the tissues. In bone, the insoluble fractions and the total collagen content showed increasing trend with advancing age. But in cartilage, the same trend was visible only in acid extraction method. The results have been compared with that of mammalian tissues.

Age related changes in the skeletal muscle of Calotes versicolor. I. Change in glycogen, total protein, ascorbic acid and water content.

Abstract Some of the biochemical components of the skeletal muscle of the garden lizard, Calotes versicolor , have been analysedd in relation to age. The glycogen content (mg/100 g wet wt.), reached a peak at about 40 g body weight, followed by a slight decline during the later half of the life span. The total protein (mg/g wet wt.) showed gradual decline till about 40 g bodyweight remaining almost constant thereafter. The total ascorbic acid (mg/100 g wet wt.) declined gradually during the entire life span. A tendency for increase in water percentage with advancing age was observed.

Age related changes in the solubility of collagen in the bone and skin of the garden lizard, Calotes versicolor.

Abstract In the garden lizard, Calotes versicolor , the labile collagen decreases in the skin and bone from 39·6 and 1·5 per cent at 13–17 g body weight, to 14·1 and 0·23 per cent respectively at 55–65 g. Thus collagen ages in this lizard as in mammals. The collagen content of skin (mg/100 mg dry wt.) shows a tendency to rise with increasing body weight. In bone there is an increase till the lizards weigh about 55 g and then a sharp decline.

Change in ascorbic acid and water content of the liver of garden lizard during ageing and partial hepatectomy.

Abstract The relative ascorbic acid (mg/100 g wet wt) content of the liver of Calotes versicolor, showed significant age related decline. Ascorbic acid level of the whole liver (μg/whole liver wet wt) indicated an increasing trend till 40 g body weight, remaining constant thereafter. The water content of the liver shows tendency to decline during ageing. Partial hepatectomy induces a decreased level of ascorbic acid at 4 hr of operation and an increased level at 24 hr. Such changes do not seem to be age dependent. The decreasing level of water content of the liver at 4 hr of hepatectomy seems to be more prominent in younger lizards. At 24 hr of hepatectomy, the declining trend was still observed in younger lizards whereas in older lizards, the water content increased.

Effect of age and hepatectomy on the glycogen content of the liver of the garden lizard, Calotes versicolor

Abstract The glycogen content of the liver of Calotes versicolor , expressed on the basis of unit wet weight, dry weight and DNA content, shows an increase till the lizards weigh 44–47 g and then declines. Glycogen per total liver also shows the same trend. Partial hepatectomy leads to a fall in glycogen content in early hours and then there follows a return to initial level at 24 hr of operation. The age of the lizard does not seem to influence the rate and nature of such changes.

Nucleic acid and protein contents in the brain of the ageing teleost, ophiocephalus punctatus bloch

Abstract The DNA content in the brain of the teleost O. punctatus of either sex declined significantly during sexual maturity and thereafter showed a rise. On the other hand, the RNA and protein content and the RNA/protein ratio indicated a peak level around year-class 1+ and then showed a declining trend.

Correlation between bodyweight, snout to vent length, tailgirth and metabolic rate in male garden lizards (Calotes versicolor)

Abstract The snout to vent length and the tail girth of the male garden lizards show significant increase in relation to bodyweight. The increase in these parameters is more prominent during early stages than in the later half of the lifespan suggesting that the growth rate in this reptile declines with age. The metabolic rate as indicated by oxygen consumption studies also declines with increasing bodyweight.