Research Abstract |
Researchers in US found the calcitonin (CT) mRNA in the uterus of rats, and supposed that CT may make a suitable environment of Ca for cellular adhesions and differentiation of organs in eiobryos. We were stimulated by their report, and tried to amplify the CT cDNA in the testes and ovaries of goldfish by RT-PCR method. As a result, the same sequence of the nucleotides as the ultimobranchial calcitonin was amplified from homogenates of those gonads. Furthermore, we found CT-immurioreactive axons of neurons in the testis of goldfish. Therefore, we planed to examine the access points of the axons of the CT-producing neurons, using tilapia, because those axons may be terminated at muscles or steroid-producing cells in the gonads. In addition, we were going to ablate the neural ganglion in the gonads, and to observe the effects. In tilapia, however, the neural ganglion was not immunoreacted against the anti-CT antiserum, and was not compact but dispersed. Therefore, this project was judged
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to be impossible to do, although we are regretted very much. However, we stuck at the expression of CT in gonads, and examined the presence of CT mRNA in salmon eggs. As a result, we could amplify CT cDNA by RT-PCR method in the egg membrane just ovulated and on the way,of embryo-developing. The amplification rate was larger in the animal pole side than that in the vegetal pole side. Furthermore, CT cDNA could be amplified from yolk as well. The pattern was similar to that in the egg membrane. Although we amplified the elongation factor as the control, the results were similar. Therefore, we could not conclude that distribution pattern of the CT mRNA is specific or not. In the egg membrane just after hatching out of fry, CT cDNAwere amplified as well. We made oral presentation about this result at 71 annual meeting of Zoological Society of Japan in Yamagata, 2000 (Zool. Sci., 17 suppl. 6p). As this result must be the first finding, we will continue to make a research about this phenomenon. Less
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