Calotes Research Articles

Age related changes in the skeletal muscle of Calotes versicolor—II. Correlation between RNA, total protein and free amino acids pool; changes in protein fractions

The RNA content of the skeletal muscle of the garden lizard, Calotes versicolor declined sharply till maturity, remaining constant thereafter. Correlated with this, the total protein content showed a decreasing age related trend and the free amino acids pool a rising tendency. The “myogen” protein fraction of the skeletal muscle showed increasing accumulation till maturity, followed by a slower decline. The concentration of contractile protein fraction (myosin and actin) increased with advancing age and that of stroma protein declined sharply till maturity remaining almost constant thereafter.

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

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.

Effect of light and darkness on the hypothalamo-neurohypophyseal system of the garden lizard, Calotes versicolor.

Nous avons étudié l'effet d'une l'illumination continue ou d'une obscurité de 7 jours sur le système hypothalamique neurosécréteur (HNS) du lézard des jardinsCalotes versicolor. L'illumination a stimulé le HNS par activation de la synthèse, du transport et de la libération de la neurohormone(s) tandis que l'obscurité a fait diminuer la quantité libérée de neurohormone de la pars nervosa.

Male hormone and thyroid function in the Indian garden lizard, Calotes versicolor.

Seasonal changes in the thyroid gland related to temperature and reproductive cycles have been observed in a number of reptiles. However, while the temperaturedependence of the thyroid has been well established, experimental studies aimed to demonstrate a direct association between reproductive events and thyroid secretions have so far been lacking (see reviews by Dodd & Matty, 1964; Lynn, 1970). We have now obtained data indicating that male hormone(s) may be of great importance in the maintenance of thyroidal function in lizards. Indian garden lizards (Calotes versicolor) were housed in a temperature (31 ± 1 °C and photoperiod (12 h light) controlled chamber. Live maggots and water were provided ad libitum. In June, 15 adult males were castrated and 10 were sham-operated under sodium pentobarbitone anaesthesia. After 5 weeks each animal received i.p. 10 μCi carrier-free 131I in 0·2 ml 0·9% NaCl solution. Four to five animals from each group

Seasonal variation in thyroid hormonogenesis in the Indian garden lizard, Calotes versicolor.

SUMMARY The metabolism of radioactive iodine in the adult male garden lizard, Calotes versicolor, was studied during the course of a year by examination of the following indices of thyroid function: thyroidal 131I uptake, quantitative estimation of labelled iodoamino acids in the thyroid gland and in plasma, and plasma protein-bound iodine. Labelled monoiodotyrosine, di-iodotyrosine and thyroxine were identified and seasonal variations in their proportions demonstrated. Thyroxine was not detected in winter but made its appearance in the spring and summer months. Tri-iodothyronine was not detected at any time of the year in the thyroid of Calotes. The effects of administration of thyrotrophin (TSH), lowered temperature and dehydration were also studied. TSH augmented 131I incorporation into the thyroid gland significantly but was not effective in stimulating hormonogenesis in winter. While water withdrawal had no effect on thyroidal radioactive iodine uptake, temperature lowered artificially (15 °C) in summer reduced it by half, and altered greatly the proportions of iodoamino acids in the thyroid. The results are discussed in the light of the fragmentary information concerning thyroid function in reptiles.

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

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.

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

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.

Histochemical observations on the granulosa (follicular) cells in the preovulatory and postovulatory follicles of garden lizard ovary.

Histochemical observations on the granulosa (follicular) cells in the preovulatory and postovulatory follicles of garden lizard ovary.

Ageing changes in the brain of the garden lizard, calotes versicolor—I. Change in brain weight/body weight ratio, water content, total lipid and phospholipid

In the garden lizard, Calotes versicolor, the brain weight/body weight ratio declines with increasing body weight but remaining almost constant beyond 40 g. The water content of the brain also remains nearly constant during the life span of the lizard. Total lipid (mg/whole brain) increases linearly till 50 g body weight followed by a steeper linear trend. The relative lipid content (mg/g fresh wt.) shows a slight initial increase but remaining almost flat up to 50 g and then follows a significant rise. The phospholipid content (mg/whole brain) shows a light initial increase followed by a decline till 68 g. There is a continuous decline in relative phospholipid content (mg/g fresh wt.) beyond 16 g body body weight.

Ageing changes in the nucleic acid and protein content of the liver of the garden lizard, Calotes versicolor

The relative DNA content (mg/g wet wt.) of the lizard liver declined sharply during postnatal stage remaining almost constant during the laterhalf of the life-span. The total DNA (mg/whole liver wet wt.) was found to increase with increasing bodyweight. The relative RNA content (mg/g wet wt.) reached the peak level at 16 g body weight and declined thereafter. The total RNA (mg/whole liver wet wt.) showed the same tendency as observed for total DNA. The relative protein content (mg/g liver wet wt.) showed the highest concentration at about 30 g bodyweight and remaining constant thereafter. When expressed on the basis of DNA (mg protein/mg DNA) the protein content also reached a peak level at about 30 g body weight but showed decline thereafter. The total protein (mg/whole liver wet wt.) indicated a steady rise with increasing age but at much slower rate beyond 50 g body weight. The RNA/ DNA ratio was highest at about 16 g body weight and declined thereafter. The RNA/Protein ratio also showed the similar trend.

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

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.

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

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.

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

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.

Age related changes in the Ca/P molar ratio in the bones of the garden lizard Calotes versicolor

There is a gradual shift of Ca/P molar ratio in the bones of the garden lizard Calotes versicolor till they weight about 29 g. At this stage, the Ca/P molar ratio seems to be as in apatite. In older animals the apatitic ratio is maintained with a range of variation from 10 5·1 to 10 6·5 . It is probable that the structure of collagen acting as template for calcification, is not deranged during this phase of life-span of the lizard.

Some Observations on the Development ofSpirocerca lupiin its Intermediate and Definitive Hosts

1. Infective larvae ofS. lupiwere collected in Madras from scarabaeid beetles, (the usual intermediate host), from garden lizards and shrews.2. The structure and relative sizes of the larvae in the 3 kinds of hosts are compared.3. Infective larvae were given orally to 30 dogs which were autopsied at intervals and the developing worms were recovered. Their growth was measured and some observations were made on their development during the prepatent period which was found to be 121 and 124 days.

Morphology of ovarian changes in the garden lizard, Calotes versicolor.

AbstractOvarian changes during the reproductive cycle of the oviparous garden lizard (Calotes versicolor) are described. It ovulates from last week of June to first week of September but most often in July and August when the monsoon occurs. The number of eggs ovulated vary from 10 to 32. After ovulation, the ovaries are reduced in size. From October to May, the ovaries contain small pre‐vitellogenic follicles, which increase in size in June when most of yolk deposition occurs. Several nuclei are seen in the ooplasm of pre‐vitellogenic follicles; they are finally absorbed before yolk deposition starts. Follicular atresia generally occurs in follicles with polymorphic granulosae, in post‐ovulatory ovaries. Presumably interstitial gland cells are formed by the hypertrophy of the theca interna cells of atretic follicles. Pre‐ovulatory follicles have highly vascularized thecae and invaginations of the follicular epithelium. After ovulation, the follicle cells hypertrophy to form the luteal cell mass filling the follicular cavity. Fibroblasts, which appear to arise from the theca interna, invade the luteal cell mass and form septa. Capillaries occur in the luteal cell mass.

Analysis of the development of the lizard, Calotes versicolor. I. A series of normal stages in the embryonic development

AbstractIt has been shown that the external parameters of eggs of the garden lizard, Calotes versicolor, are not suitable for assessing the exact developmental stages of embryos. In order to make use of this lizard's embryos for experimental work, a series of developmental stages has been characterized, using various morphological features.

Histochemical studies on the neurosecretory system of the common garden lizard Calotes versicolor (Daudin) under experimental condition

Histochemical localizations of various substances in the hypothalamic neuro-secretory cells as well as neurohypophysis of the normal and stressed (scalded) garden lizards, Calotes versicolor suggest that the neurosecretory materials, secreted by the hypothalamic neurones may be a mucoprotein-lipoprotein complex which is finally stored in the neuro-hypophysis. Only the proteinaceous fraction of this complex appears to be released by the nerve terminals in the neurohypophysis under the stressed condition. Such suggestion implies a chemical transformation of neurosecretory substances after leaving the neurosecretory cell body.

Hypothalamic control of the pars intermedia of the pituitary gland in the garden lizard, Calotes versicolor

Subcutaneous or intraperitoneal injections of graded concentrations of formalin or sodium chloride were administered to batches of garden lizard, Calotes versicolor. The animals were sacrificed at intervals varying from 10 min to 5 days after the injections. The hypothalami and pituitary glands were studied using Gomori's chrome-alum-hematoxylin and aldehyde-fuchsin techniques. Within 2 min of the injection the animal changes color very vividly; and the brilliant coloration persists as long as the stress continues. In both groups of experiments the pars intermedia showed heightened secretory activity as evidenced by nuclear and nucleolar enlargement and the appearance in the cytoplasm of phloxinophilic granules of colloid material. The neural lobe showed massing of the neurosecretory material (NSM) around the capillary loops in the mild cases, to frank depletion in more severe cases. The capillary beds of the neural and intermediate lobes showed marked dilatation. Calotes, when exposed to stressful stimuli, react by an increased secretory activity and output by the cells of the posteroinferior part of the nucleus paraventricularis. Neurosecretory material is rapidly discharged into the neurointermediate portal vessels and made to circulate in the pars intermedia, stimulating the latter to secretory activity. It may be concluded that the hypothalamic control of pars intermedia is through the agency of circulating NSM and that the influence is stimulatory, not inhibitory as has been reported for most other vertebrates.

Reaction of the paraventricular nucleus to dehydration in the garden lizard, Calotes versicolor

Adult garden lizards of both sexes were subjected to dehydration by giving them intraperitoneal injections of sodium chloride solution, the concentration of which varied from 0.5 M to 1.0 M. Each animal was given one injection daily up to 5 days and sacrificed 6 to 8 hours after the last injection. In the early phases of dehydration, the cells of the Paraventricular nucleus showed high secretory activity by nuclear and nucleolar enlargement. In more severe cases, signs of cell degeneration and death were seen. The supraoptic nucleus showed no changes except in the most severe dehydration. It is concluded that in the garden lizard the Paraventricular nucleus is the seat of production of the antidiuretic hormone, which in mammals and birds is elaborated by the supraoptic nucleus.