5-Bromo-2’-deoxyuridine induces visible morphological alteration in the DNA puffs of the anterior salivary gland region of Bradysia hygida (Diptera, Sciaridae)

5-Bromo-2’-deoxyuridine (BrdUrd) has long been known to interfere with cell differentiation. We found that treatment ofBradysia hygida larvae with BrdUrd during DNA puff anlage formation in the polytene chromosomes of the salivary gland S1 region noticeably affects anlage morphology. However, it does not affect subsequent metamorphosis to the adult stage. The chromatin of the chromosomal sites that would normally form DNA puffs remains very compact and DNA puff expansion does not occur with administration of 4 to 8 mM BrdUrd. Injection of BrdUrd at different ages provoked a gradient of compaction of the DNA puff chromatin, leading to the formation of very small to almost normal puffs. By immunodetection, we show that the analogue is preferentially incorporated into the DNA puff anlages. When BrdUrd is injected in a mixture with thymidine, it is not incorporated into the DNA, and normal DNA puffs form. Therefore, incorporation of this analogue into the amplified DNA seems to be the cause of this extreme compaction. Autoradiographic experiments and silver grains counting showed that this treatment decreases the efficiency of RNA synthesis at DNA puff anlages.

THE EFFECT OF CAPSAICIN UPON DMBA INDUCED CANCEl OF THE BUCCAL POUCH IN HAMSTERS

Cancer chemoprevention can be defined as prevention or intervantion of cancer by the administration of one or chemical entities, either, either as individual drugs or as naturally occurring constituents of the diet. The name capsaicin(trans-8-methyl-N-vanillyl-6-nonenamide) was given by Thresh in 1848, and capsaicin is a primary pungent and irritating princple present in red peppers which are windely used as spices in korean food. The inhibitory effect of capsacin on stomach or skin cancers had been reported in lots of animal studies, but there were few reports In offal cancer carclnogenesls. This study is aimed to see the effect of capsalcln upon DMBA induced cancer of the buccal pouch in hamsters. In thls study, 87 Golden Syrian hamsters, weighing about 80-90g, were used and divided into 5 group : normal group (n=2)-untreated : control group(n=15)-DMBA painted : experimental group I(n=23)-capsaicin(10 micromol/2ml) and DMBA painted ; experimental groupII(n=23)-capsaicin administered and DMBA painted ; experimental group III(n=24)-administered and patinted. DMBA painted. According to groups, the animals were sacrificed at 5, 8, 11, 14, 17 week. Microscopic examination was done and BrdUrd labeling Index was calculated. The results are as follows : 1. According to gross examination, the leukoplakia at 5 week and the papilloma at 8 week were shown in the experimental group I, III. Those feature were appeased rapider than those of the control and expefimental group II. 2. According to gross examination, the exophytic tumorous lesions were shown in the control and all of the experimental groups from 14week, but the features of the control group were severer than those of the experimental groups. 3. According to histopathologic features, the papilloma was shown in all of the experimental group except the control group at 8 week 4. Histologically, the features of the control group were severer than those of the experimental groups from 14 week and there were similar features among the experimental group I, II, III at 17 week 5. At 8 week, BrdUrd labeling index of experimental group I, III were than that of control group and it was statistically significant (p<0.05) 6. The BrdUrd labeling index of experimental group III from 11week, experimental group I from 14week, experimental group II from 17 week were lowed than that of the control group respectively and It was statistically significant(p<0.05) 7. In the distribution of the BrdUrd labeled cells, BrdUrd was more significant in the basal and parabasal cell in dysplatic changes, but in carcinoma in situ, BrdUrd showed a irregular arrangement throughout the whole thickness of the tumor epithelium According to the abone results, the irritating property of the capsaicin accelerated the carcinogenesis in early phase, but the inhibitory effect was shown from carcinoma in situ phase. So the chemopreventive effect of the capaicin which is a major ingredient of red pepper can be expected. However, the further studies including the amount and method of capsaicin administration for preventive effect of oral cancer, should be followed.