Many genes are known to be involved in gonadal differentiation in vertebrates. Dmrt1, a gene that encodes a transcription factor with a DM-domain, is considered to be one of the essential genes controlling testicular differentiation in mammals, birds, reptiles, amphibians and fish. However, it still remains unknown which testicular cells of animals other than mice and chicks express Dmrt1 protein. For an explanation of its role(s) in testicular differentiation in vertebrates, the expression of the Dmrt1 protein needs to be studied. For this purpose, we conducted an immunohistochemical study of this protein in an amphibian by using an antibody specific for Dmrt1. No positive signal was found in the indifferent gonad of tadpoles of Rana rugosa at early stages. However, in the testis of tadpoles at later stages (XV–XXV) and in frogs one month after metamorphosis, this protein was expressed in interstitial cells and Sertoli cells. In the testis of adult frogs, germ cells also expressed Dmrt1 protein. RT-PCR analysis revealed that the gene for this protein was not transcribed at any time during ovarian development, but was expressed in the female to male sex-reversed gonad. This was true when immunohistological studies were performed. In addition, Southern blot analysis showed Dmrt1 to be an autosomal gene. Taken together, our findings indicate that Dmrt1 protein is expressed by interstitial cells, Seroli cells and germ cells in the testis of R. rugosa. Dmrt1 may thus be very involved in the testicular differentiation of amphibians.
The ventral skin of the wild Japanese newt Cynops pyrrhogaster is creamy at metamorphosis, but turns red when mature. The color of the ventral skin of laboratory (lab)-reared newts stays yellow throughout their life. However, the mechanism for the red coloration of this animal still remains unknown. In this study, we have performed ultrastructural and carotenoid analyses of the red ventrum of wild and lab-reared Japanese newts. Using electron microscopy, we observed a number of xanthophores having ring carotenoid vesicles (rcv) and homogenous carotenoid granules (hcg) in the ventral red skin of the wild newt. In the skin, beta-carotene and five other kinds of carotenoids were detected by thin-layer chromatography (TLC). In the ventral yellow skin of lab-reared newts, however, only beta-carotene and three other kinds of carotenoids were found. The total amount of carotenoids in the red skin of the wild adult newt was six times more than that of the yellow skin of the lab-reared newt. Moreover, rcv were more abundant in xanthophores in red skin, but hcg were more abundant in yellow skin. These results, taken together, suggest that the presence of carotenoids in rcv in xanthophores is one of the critical factors for producing the red ventral coloration of the Japanese newt C. pyrrhogaster.
ABSTRACT. Equine carbonic anhydrase isozymes (CA-I and CA-II) were purified from erythrocytes by several column chromatography. Polyclonal anti-CA-I and anti-CA-II sera were produced in rabbits. Sensitive competitive enzyme-linked immunosorbent assays (ELISA) were established to determine the developmental changes in CA-I and CA-II levels in equine erythrocytes. Concentrations of CA-I and CA-II in erythrocytes from 150 clinically normal thoroughbreds (123 racehorses and 27 riding horses) were determined by ELISA. Mean (± SD) concentrations of CA-I and CA-II in racehorses were 1.70 ± 0.48 and 0.94 ± 0.13 mg/g hemoglobin (Hb), respectively. Mean concentrations of CA-I and CA-II in riding horses were 2.34 ± 0.52 and 0.76 ± 0.08 mg/g Hb, respectively. When the CA levels in racehorses and riding horses were compared, the CA-I level in riding horses was higher than that in racehorses (p=0.01). The CA-II level in racehorses was higher than that in riding horses (p=0.02). These data suggest that the levels of CA isozymes in erythrocytes of racehorses were influenced by chronic physical stress. The CA-I concentration in erythrocytes of 2-month-old horses was approximately 0.25 mg/g Hb. The CA-I level noticeably increased during the first year of life and approached normal adult levels by 2 years. The CA-II level decreased slightly with age, indicating different regulation of CA-I and CA-II expression during development. KEY WORDS: carbonic anhydrase, equine, ELISA, erythrocyte.
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