Effects of restrictions in dietary protein and vitamin A on the responses of rats to infections by Nippostrongylus brasiliensis (Nematoda) and N. brasiliensis plus Eimeria nieschulzi (Coccidia)

The effects of adequate and restricted dietary protein and vitamin A on responses to infections by Nippostrongylus brasiliensis and N. brasiliensis plus Eimeria nieshulzi were determined in growing Sprague-Dawley rats. Infected rats experienced anorexia followed by a rebound in consumption that compensated for weight losses during anorexia. On certain days, reductions in the urinary/fecal nitrogen ratio, fecal and absorbed nitrogen, and apparent nitrogen and dry matter digestibilities occurred with the combined infections but not with those by nematodes alone. Effects of different levels of vitamin A were expressed only as an increase in nitrogen absorption occurring during the post-anoretic increase in appetite found with infected rats and in rats restricted in protein but receiving the higher level of the vitamin. Protein level was the most significant treatment effect: rats on high protein performed significantly better than those on low, regardless of the level of the other experimental variables.     

Viability of Culex pipiens pipiens eggs affected by nutrition and aposymbiosis

Raisins were a better source of carbohydrate than sucrose for reproduction by autogenous Culex pipiens. A blood meal increased the number of eggs per raft from 49 autogenously to 114. Eggs of aposymbiotic females produced autogenously did not hatch, but 34% of the eggs were viable if the mosquitoes fed on chickens. With repeated blood meals the number of eggs per raft and the rate of embryonation and hatching declined in each successive gonotrophic cycle. In about $\text{1}\text{4}$ of the unhatched eggs of normal females there were no fully developed embryos, while many more of the unhatched eggs of aposymbiotic females contained no evidence of embryonic development. After the fifth blood meal, neither normal nor aposymbiotic insects oviposited. The ovaries of the nulliparous females contained approximately 10% of the potential number of mature terminal oocytes. Proximally in the ovarioles there were dilatations and coiled tracheoles indicating egg resorption. There were fewer parous follicles in aposymbiotic than in normal females. Larval rearing water, i.e., infusion in which larvae had been reared, was more attractive than fresh infusion for oviposition by normal, autogenous mosquitoes. The degree of embryonation of the eggs was lower and the hatching success rate was poorer in fresh infusion than in larval rearing water.     

The nutrition of stomachless phytoplanktivorous fish in comparison with Tilapia

The contents of alimentary tracts of stomachless phytoplanktivorous fish, including silvercarp (Hypophthalmichthys molitrix), Esomus danrica thermoicos, and Amblypharyngodon meletinus were investigated microscopically and compared with those of Tilapia (Oreochromis mossambicus, a fish with stomach).The predominance of detritus in the food and the low efficiency with which phytoplankton is utilized prove, that stomachless fish are not primarily herbivorous. The possibility of omnivorous feeding as an alternative is discussed. These results may contribute to our understanding of the role of filterfeeders in aquaculture and ecosystems.     

Peptostreptococcus barnesae sp. nov., a Gram-positive,anaerobic, obligately purine utilizing coccus from chicken feces

Anaerobic, Gram-positive cocci were obtained from chicken feces by direct isolation, which grew on the purines uric acid, xanthine, 6,8-dihydroxypurine, guanine, and hypoxanthine. Adenine and glycine were fermented, but not as readily. Acetate, formate, ammonia, and CO₂ were products. The isolated strains were nutritionally non-fastidious, however, they required selenite, molybdate, and tungstate as micronutrients. The cells were spherical and 0.5–0.9 m in diameter. The addition of bile salts enhanced the growth rate in most cases. The organisms proved to be quite resistant to lysis. The guanosine-plus-cytosine (G+C) content of their deoxyribonucleic acid was 33.6 to 34.8 mol%. The peptidoglycan was of the same structure (Gly-Lys-d-Asp) as reported for the anaerobic cocci of Hare group IX. However, the latter strains could only utilize glycine, not purines. Therefore, it is proposed to form a new species, Peptostreptococcus barnesae sp. nov.This paper is dedicated to Prof. Dr. Norbert Pfennig on the occasion of his 60th birthday     

饲料硒和维生素E对大鼠机体抗氧化能力的影响

 用克山病病区粮配成基础低硒饲料,补充硒和/或维生素E组成四种不同水平的饲料,饲喂雄性断乳大鼠,观察其对机体抗氧化能力的影响。评价指标是用抗坏血酸诱发的红细胞溶血率、被O~-_2(超氧阴离子)氧化的血红蛋白量和组织中的TBA值。动物饲养13周后,自尾静脉取血,测定溶血率和血红蛋白被氧化的百分率,和全血SeGSHPx(含硒谷胱甘肽过氧化物酶)活力。15周后将动物断头杀死,立即取出心脏和肝脏测定SeGSHPx活力和TBA值。结果表明在克山病病区粮的饲料中补充硒或维生素E,或者二者同时补充均明显提高组织中的SeGSHPx活力和降低组织中的TBA值。不论在硒缺乏时或硒充足时,饲料中补充维生素E显著降低抗坏血酸诱发的红细胞溶血率,对O~-_2氧化血红蛋白无保护作用。在维生素E缺乏时,仅补充硒对溶血无作用。不论饲料中维生素E缺乏或者充足,补充硒对O~-_1氧化血红蛋白均有显著保护作用。     

亚硒酸钠对肿瘤细胞膜流动性及致癌性的影响

 本文为探讨硒抗肿瘤的机理而开展了硒对小鼠腹水型肝癌(Hep.A)细胞膜流动性影响的研究。结果表明;1.腹水型肝癌细胞膜流动性明显高于正常肝细胞的膜流动性。2.硒能显著降低腹水型肝癌细胞膜的流动性,而对正常肝细胞的膜流动性没有明显影响。3.通过降低腹水型肝癌细胞膜的流动性,可降低肿瘤细胞的致癌力。     

Evidence for a relationship between malate metabolism and activity of 1-sinapoylglucose: L-malate sinapoyltransferase in radish (Raphanus sativus L.) cotyledons

The control of malate metabolism and stimulation of 1-sinapolyglucose: L-malate sinapoyltransferase (SMT) activity in radish (Raphanus sativus L. var. sativus) cotyledons has been studied. The light-induced and nitrate-dependent activity of SMT catalyzes the formation of O-sinapoly-L-malate via 1-O-sinapoyl--D-glucose. When dark-grown radish seedlings, cultivated in quartz sand with nutrient solution containing NO ₃ ^- as the sole N source, were treated with light, SMT activity increased concomitantly with free malate in the cotyledons. This light effect was suppressed in seedlings grown in a culture medium which contained in addition to NO ₃ ^- also NH ₄ ⁺ . However, treatment with methionine sulfoximine neutralized this ammonium effect, resulting again in both rapid accumulation of malate and rapid increase in SMT activity. When seedlings grown on NO ₃ ^- nitrogen were subsequently supplied with NH ₄ ⁺ nitrogen, the accumulated level of L-malate rapidly dropped and the SMT increase ceased. The enzyme activity decreased later on, reaching the low activity level of plants which were grown permanently on NO ₃ ^- /NH ₄ ⁺ -nitrogen. An external supply (vacuum infiltration) of malate to excised cotyledons and intact seedings, grown on NO ₃ ^- /NH ₄ ⁺ -nitrogen medium, specifically promoted a dose-dependent increase in the activity of SMT. In summary these results provide evidence indicating that the SMT activity in cotyledons of Raphanus sativus might be related to the metabolism of malic acid.Abbreviation MSO L-methionine sulfoximine - SinGlc 1-O-sinapoyl--D-glucose - SinMal O-sinapoyl-L-malate - SMT 1-O-sinapoyl--D-glucose:L-malate sinapolytransferase     

Dietary selenium status and plasma thyroid hormones in chicks

Experiments were conducted to study the effect of marginal levels of selenium and vitamin E on plasma thyroid hormones of meattype chicks. Plasma thyroxine (T₄) was significantly increased when a semipurified diet was supplemented with either selenium or vitamin E. Triiodothyronine (T₃) was also significantly increased by vitamin E and in one experiment with selenium supplementation. No significant increase in these hormones was observed in birds fed a corn-soybean-meal diet supplemented with these nutrients. Plasma corticosterone level was reduced and weight of the bursa of Fabricius increased by selenium or vitamin E supplementation. These nutrients may be necessary for providing the optimum thyroid conditions for activity of thyroid peroxidase.     

Selenium modifies carcinogen metabolism by inhibiting enzyme induction

Since selenium has been found to exert a protective action against carcinogenesis in various systems, the mechanism where-by sodium selenite inhibits DNA binding of the carcinogen, 7,12-dimethylbenz[a]anthracene, was investigated. It was found that selenite preferentially reduced DNA binding occurring through ananti-dihydrodiol epoxide metabolite of this carcinogen by inhibiting the induction of an enzyme system that generates this specific reactive metabolite.