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doi: 10.1002/jez.1401720402pmid: 5392881
Lactate dehydrogenase (LDH) isozymes from beef tissues were injected into newly fertilized frog eggs. Embryos at various stages were examined by starch gel electrophoresis to determine whether the injected isozyme was present. Beef LDH‐1 was stable for at least twelve days following injection, while beef LDH‐5 was present in the embryos as a functional molecule for less than six days. These very different in vivo stabilities are not in agreement with the in vitro stabilities obtained here, and suggest that regulated differential stability of isozymes may be important to the organism in conferring greater metabolic flexibility during cell differentiation when the isozyme repertory commonly changes. During the degradation of beef LDH‐1, no hybrid beef‐frog LDH molecules could be detected although such molecules can be formed by a simple in vitro technique. Since frog LDH is synthesized during the degradation of the injected LDH, the lack of detectable hybrid molecules indicates that the subunits of the degraded molecules cannot be reused—either because the molecule is degraded as a whole, without the release of subunits, or because the sites of synthesis and degradation are mutually inaccessible.
Sundararaj, Bangalore I.; Nayyar, S. K.
doi: 10.1002/jez.1401720403pmid: 5373341
The response of the seminal vesicles to hypophysectomy and/or castration during the prespawning and the spawning periods was studied. Forty days post‐hypophysectomy the seminal vesicles regress completely, whereas 40 days postcastration they show hyperactivity which is accentuated by 85 days post‐surgery. Further, catfish castrated in the prespawning period of 1966 not only show hyperactive seminal vesicles in that season but also exhibit hypersecretory seminal vesicles in the following breeding season, in spite of the absence of the testes. In the castrate catfish, hyperactivity in the seminal vesicles is accompanied by a significant increase in the number and activity of the granulated basophils in the pituitary and an increase in the nuclear diameter of the interrenal cortical cells. Two hypotheses are proposed to explain this paradoxical phenomenon.
Nayyar, S. K.; Sundararaj, Bangalore I.
doi: 10.1002/jez.1401720404pmid: 5373342
Δ5‐3β‐hydroxysteroid dehydrogenase activity (Δ5‐3β‐HSD) has been studied in the interrenal glands and the seminal vesicles of intact and castrate male catfish. The intensity of the enzyme reaction is about equal in the seminal vesicles of both groups, whereas the intensity of enzyme reaction in the cortical cells is more pronounced in the castrate than in the intact male.
Sundararaj, Bangalore I.; Nayyar, S. K.
doi: 10.1002/jez.1401720405pmid: 5373343
The effect of estradiol benzoate (EB), SU‐9055, and cyproterone acetate (CA) on the hypersecretory seminal vesicles of the castrate catfish has been studied. EB to a marked extent, SU‐9055 and CA to a lesser extent inhibit castration induced hypersecretion in the seminal vesicles. This implies that while EB inhibits the gonadotrophin production, SU‐9055 and CA act at the level of the interrenal glands and the seminal vesicles respectively. The data indicate that following castration the high level of circulating gonadotrophin induces the interrenals to produce androgens which in turn bring about hypersecretion in the seminal vesicles.
doi: 10.1002/jez.1401720406pmid: N/A
To gain insight into the mechanism permitting Fundulus heteroclitus to survive subzero temperatures in a supercooled state, previously published data on inorganic components of the serum were complemented by studies on serum organic constituents in parallel groups of adult male killifish acclimated to various temperatures (30°C, 20°C, 10°C, 4°C, 2°C, −1°C and −1.5°C) in salt water under otherwise constant laboratory conditions. When the acclimation temperature was lowered from 20°C to −1.5°C, there was little or no change in levels of serum total non‐protein nitrogen, total amino acids, urea and non‐glucose free carbohydrates. Total serum protein levels were usually unaffected by the cold, but occasionally showed a decrease. Serum total cholesterol levels increased by 69% in the subzero cold, presumably due to an increased lipid metabolism. Whereas most serum constituents (organic and inorganic) showed only minor changes in supercooled F. heteroclitus, serum glucose levels increased from three‐ to sixfold. Serum glucose levels of 68 mg% in fish at 20°C increased to 460 mg% in sexually regressed fish at −1.5°C but to only 280 mg% in supercooled mature fish. It was suggested that the elevation of serum glucose in the subzero cold permitted survival in a supercooled state, presumably by retarding ice crystal growth on any ice nuclei that might form spontaneously in the blood.
doi: 10.1002/jez.1401720407pmid: 5373344
Fracture healing of the tibiofibula was examined in the frog, Rana pipiens, in which the ultimobranchial glands were removed. Extirpation of these structures presumably eliminates the hormone calcitonin. X‐ray and histological observations were made during the healing process of a closed fracture for a period of 12 weeks. The repair process of fractured bone in the first four weeks of intact and ultimobranchialectomized frogs revealed similar tissue reactions at the fracture site and followed comparable healing patterns. There was extensive cartilage formation in both groups with ossification at the periphery of diaphyseal cartilage. After eight weeks the fracture site of controls exhibited more extensive invasion and development of endochondral ossification than ultimobranchialectomized frogs. Osteoclasts were observed at the distal segment of the fracture, and throughout endochondral trabeculae. After 12 weeks, periosteal bone was well developed in controls, and poorly represented in ultimobranchialectomized frogs. Deprivation of calcitonin in frogs apparently does not affect cellular activity at a fracture site during the first four weeks. However, cellular activity is greatly reduced with a concomitant reduction in calcification after 8 and 12 weeks. This latter period corresponds to increased osteoclastic activity in ultimobranchialectomized frogs. Further, retarded repair process may also be influenced by serum calcium levels rather than by a lack of direct hormonal control on specific bone cells types.
doi: 10.1002/jez.1401720408pmid: 5392882
Experiments are described in which the differentiative capacity of the anterior embryonic shield of the teleost. Fundulus heteroclitus, was investigated by means of deletion‐transplantation techniques.
doi: 10.1002/jez.1401720409pmid: 5373345
Electron microscopic examination of newborn New Zealand white rabbit ovaries revealed numerous germ cells within the germinal epithelium during the early stages of oogenesis. The germ cells were found at all levels of the germinal epithelium, as well as in bridges connecting with the underlying sex cords. Germ cell nuclei were large and round with smooth, regular double membranes, reticular nucleoli and evenly distributed chromatin. Mitochondria were characteristically spherical with slightly eccentric cristae. The number of germ cells within the germinal epithelium gradually diminished until they were completely absent by the time oogenesis was complete.
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