The effect of epitestosterone on estrogen biosynthesis in vitro.

OBJECTIVE: The concentrations of epitestosterone in human serum correlates negatively with that of estradiol. The possible explanation of this relation was addressed, and the influence of epitestosterone on kinetics of estradiol formation in vitro was evaluated. METHODS: The concentration of epitestosterone was measured in serum of 54 men participating in a screening program for prostate disease. Epitestosterone inhibition of aromatase and 17beta-hydroxysteroid dehydrogenase activities was tested in vitro in the system consisting of human placental microsomes, NADPH or NAD and NADP respectively, and epitestosterone in increasing concentrations. Testosterone, androstenedione, estrone and 17beta-estradiol were utilized as substrates. RESULTS: A significant negative correlation between epitestosterone and estradiol levels in human male serum was found. No inhibition of aromatase activity was observed; however, inhibition of 17beta-hydroxysteroid dehydrogenase was found preferentially in the direction leading to oxidation of the C-17 hydroxy group. The inhibitory effect of epitestosterone was more pronounced with androgens as substrates. CONCLUSION: Epitestosterone could influence the formation of estradiol in vitro rather by inhibition of 17beta-hydroxysteroid dehydrogenase than by blocking aromatase activity.     

闽东约马蜂的生物学习性观察

约马蜂PolistesjokanamaeRadoszkowski是一种习见的社会性天敌昆虫。研究表明约马蜂在闽东地区于4月中旬觅址筑巢,历经40d建成31~40个巢房的小巢。约马蜂1年发生2代,第1代蜂于5月下旬开始羽化,7月初蜂巢拥有职蜂可达30只,每只职蜂日均外勤达14次,群体进入快速增长期;第2代蜂8~9月间出现,雄蜂所占比例超过1/3,群体进入鼎盛期。第2代雌蜂与雄蜂交尾后于11月陆续离巢越冬。幼体发育历期28~37d,与外界气温密切相关,随温度升高而缩短。文中还提出计算幼体发育历期的方法。     

Observations of the biological characteristics of Holcocerus vicarius Walker

结合田间观察和室内试验,对榆木蠹蛾Holcocerus vicarius Walker的生物学特性进行了较为系统的研究.结果表明,榆木蠹蛾在宁夏3年发生1代,幼虫主要危害枝干和根颈部,幼虫在蛀道内越冬,5月下旬老熟幼虫在被害树周围5～10cm深的沙土内分散化蛹,蛹期(21±5)d.6月初成虫开始出现,有2个羽化高峰,分别为6月中旬和7月下旬,成虫羽化当晚即可交尾,交尾当天或第2天产卵,每雌蛾产卵最多达720粒,卵期(17±5)d,孵化率为72％～88％.未交尾雌雄成虫寿命为5～6d,交尾后雌雄成虫寿命缩短为3～5d.初孵幼虫于6月中旬始见,10月下旬幼虫开始越冬.幼虫孵化后,先危害韧皮部,常10多条聚集在一起,稍大一点即蛀入木质部.本研究为制定切实可行的榆木蠹蛾有效防治提供理论依据.     

榆木蠹蛾生物学特性观察

结合田间观察和室内试验,对榆木蠹蛾HolcocerusvicariusWalker的生物学特性进行了较为系统的研究。结果表明,榆木蠹蛾在宁夏3年发生1代,幼虫主要危害枝干和根颈部,幼虫在蛀道内越冬,5月下旬老熟幼虫在被害树周围5—10cm深的沙土内分散化蛹,蛹期（21±5）d。6月初成虫开始出现,有2个羽化高峰,分别为6月中旬和7月下旬,成虫羽化当晚即可交尾,交尾当天或第2天产卵,每雌蛾产卵最多达720粒,卵期（17±5）d,孵化率为72％～88％。未交尾雌雄成虫寿命为5—6d,交尾后雌雄成虫寿命缩短为3—5d。初孵幼虫于6月中旬始见,10月下旬幼虫开始越冬。幼虫孵化后,先危害韧皮部,常10多条聚集在一起,稍大一点即蛀入木质部。本研究为制定切实可行的榆木蠹蛾有效防治提供理论依据。     

Role of glycosylation on the secretion and biological activity of erythropoietin.

The erythropoietin (EPO) molecule contains four carbohydrate chains. Three contain N-linkages to asparagines at positions 24, 38, and 83, and one contains an O-linkage to a serine at position 126. We constructed human EPO variants that eliminated the three N-glycosylation sites by replacing the asparagines with glutamines singly or in combination. The O-linked carbohydrate chain was removed by replacing the serine with glutamine, valine, histidine, or alanine. A variant with a double mutation (Gln38,83) and another with a triple mutation (Gln24,38,83) were secreted poorly from COS1 and CHO cells even though RNA encoding these variants was present. All other variants with mutations in N-linked glycosylation sites were secreted normally. Removal of any of the N-glycosylation sites reduced the in vivo but not the in vitro biological activity of the EPO molecule. All the mutations at Ser126, the O-glycosylation site, were secreted normally. In vitro activity was also unaffected except for Ala126 which had a 50-fold decrease. The Val126 variant was tested in vivo, and its specific activity was only slightly less than that of the native EPO, which indicates that the O-linked carbohydrate is not essential for activity.     

Effects of androstenedione administration on epitestosterone metabolism in men

Androstenedione is a steroid hormone sold over-the-counter to individuals who expect that it will enhance strength and athletic performance. Endogenous androstenedione is the immediate precursor of testosterone. To evaluate the metabolism of oral androstenedione, we randomly assigned 37 healthy men to receive 0 (group 1), 100 mg (group 2), or 300 mg (group 3) of androstenedione in a single daily dose for 7 days. Eight-hour urines were collected 1 day before the start of androstenedione, and on days 1 and 7. Using gas chromatography-mass spectrometry, we measured excretion rates of glucuronide-conjugated epitestosterone, its putative precursor (E-precursor), and metabolites (EM-1 and EM-2), and we evaluated possible markers of androstenedione administration. Day 1 and 7 rates were not different: the means were averaged. The means (microg/h) for groups 1, 2, and 3, respectively were, for epitestosterone 2.27, 7.74, and 18.0; for E-precursor, 2.9, 2.0, and 1.5; for EM-1/E-precursor 0.31, 1.25, and 2.88; for EM-2/E-precursor 0.14, 0.15, and 1.15; for testosterone/epitestosterone (T/E) 1.1, 3.5, and 3.2. Epitestosterone, EM-1, and EM-2 excretion was greater in groups 2 and 3 versus group 1 (0.0001 < P < 0.03), as were EM-1/E-precursor, EM-2/E-precursor, and T/E. E-precursor excretion was lower in groups 2 (P = 0.08) and 3 (P = 0.047) versus group 1. Androstenedione increases excretion of epitestosterone and its two metabolites, while decreasing that of its precursor. Elevated ratios of EM-1- and EM-2/E-precursor, and the presence of 6alpha-hydroxyandrostenedione are androstenedione administration markers.     

Observations on the vapour phase activity of some foliage fungicides

By means of a Botrytis fabae/Vicia faba bio-assay technique it has been demonstrated that phenyl mercury chloride, maneb, mancozeb, dichlo-fluanid and oxythioquinox protect areas of leaf beyond the visible limits of the fungicide deposits. The evidence suggests that the extended areas of protection are due to the release of fungicidal vapours. For a given dose of mancozeb the area of protection was related to the number of conidia of B. fabae dusted on to the leaves and for a given inoculum density it extended with increasing fungicide dose applied in standard drop sizes. When the same dose of fungicide was applied in increasing volumes of water, producing widening areas of deposit, the area of protection also increased. Fungicide deposits aged on leaves for up to 4 weeks continued to release toxic vapours. Contact between the fungicides and leaves or between fungicides and spores was not necessary for the demonstration of the phenomenon since vapours diffused from deposits on glass and inhibited the germination of spores in water droplets placed at a distance from the fungicide source. For a given distance separating the fungicide and the spores inhibition increased with increasing fungicide dose. For a standard fungicide dose, inhibition decreased with increasing distances between the fungicide and the spores. The fungicidal vapours inhibited the germination of spores of test fungi other than B. fabae. The practical implications of these observations are examined in the light of evidence that vapour phase protection can occur on leaves incubated in large cabinets; on leaves pre-incubated at unsaturated humidities; and on leaves incubated in a moving stream of air.