人工补充寄主卵对松林内卵蜂种群消长的影响

在不同生境的松林中,人工补充寄主卵都能提高寄生效果。但林地生境不同,寄生率有明显差异。在松阔混交林中补充寄主,其寄生率比对照提高5.5—16.2倍。植被稀疏的纯松林效果较差,补充的寄生率比对照提高3.0倍。 卵蜂种群消长随季节温度而变化,全年以5月中旬至6月下旬和9月中旬至10月中旬为两个寄生高峰。卵蜂种群与松毛虫种群的消长存在较明显的相依关系,卵蜂种群随着松毛虫种群的消长而消长。施药对卵蜂种群有较大影响,施药区比对照区的寄生率约降低一倍。在混交林中填充寄主卵,能促进卵蜂种群世代延续。在逐步改善林地生境的基础上,利用人工补充寄主,可以代替人工繁蜂放蜂。     

Adrenocortical suppression in workers manufacturing synthetic glucocorticoids.

A man who had worked for 16 years in the manufacture of a potent corticosteroid was found to be suffering from chronic adrenocortical insufficiency attributed to chronic absorption of the glucocorticoid. Eleven other symptom-free workers were therefore screened. Two of these workers, like the first patient, gave grossly abnormal responses to the Synacthen (tetracosactrin) test; one had been employed for only seven months. All 12 men had facial plethora, suggesting absorption of the drug in spite of their having adhered to the safety precautions. All workers manufacturing potent steroids should therfore be screened regularly by measurement of their plasma cortisol concentrations and should be moved regularly to processing other drugs.     

Glucofructosan biosynthesis in Fusarium oxysporum: Regulation and substrate specificity of fructosyl transferase and invertase

Mycelium of Fusarium oxysporum grown on a glucose-containing medium lacked fructosyl transferase and invertase activities. Synthesis of fructosyl t     

Microbial transformation of sterols

Summary Arthrobacter simplex, Serratia marcescens, Fusarium and Mycobacterium were tested for their ability to transform phytosterol to Androsta 1, 4 diene 3, 17 dione (ADD). Arthrobacter simplex ATCC 6946 was found to be more efficient than the other species tested.     

A simplified radioenzymatic assay for dihydrofolate reductase using [3H]dihydrofolate

This report describes a simple method to measure the activity of dihydrofolate reductase using the substrate [³H]dihydrofolate, which is generated by preincubation of [³H]folic acid for 10 min with dithionite before the enzymatic reaction. The procedure then measures the direct reduction of [³H]dihydrofolate to [³H]tetrahydrofolate by coprecipitating the unreduced substrate with excess unlabeled folic acid and acidified zinc sulfate. The advantage of this method is that [³H]dihydrofolate, which is not commercially available, can be generated from high specific activity [³H]folic acid, which is commercially available, immediately before initiating the enzymatic reaction. By this modification, the two important advantages of radioenzymatic assays for dihydrofolate reductase can be more easily exploited; namely, increased sensitivity because much less substrate need be used, and the ability to measure enzyme activity in crude tissue preparations without interference by precipitating proteins or nucleotide oxidases.     

Raman and infrared spectroscopic study of gramicidin A conformations

Raman scattering and infrared spectroscopic techniques were used to study the vibrational spectrum and conformation of the membrane channel protein gramicidin A in the solid state, in organic solutions and, using Raman scattering only, in a phospholipid environment. The investigation also includes measurements on head- and tail-group-modifled gramicidin A and a potassium thiocyanate-gramicidin A complex. Tentative identification of the molecular vibrations is proposed on the basis of the data on model compounds. The existence of four distinct conformations of the gramicidin A chain is established: conformation I present in the solid state, and CH₃OH and CD₃OD solutions; conformation II present in films cast from CHCl₃ solution; conformation III present in (CH₃)₂SO and (CD₃)₂SO solutions at concentrations below 0.5 m gramicidin A; and conformation IV present in the potassium thiocyanate-gramicidin A complex. The data obtainable on a gramicidin A-phospholipid suspension indicate a gramicidin A conformation in this environment corresponding either to the conformation I or II. The details of the spectra in the amide I region are shown to be consistent with a β-parallel hydrogen-bonded π_LD helix for conformational I, in terms of the polypeptide vibrational calculations of Nevskaya and co-workers. Conformation II is found to be consistent with an antiparallel double-stranded π_LD helix, while conformations III and IV probably have π-helical structures with larger channel diameters. The data on head- and tail-modified gramicidin A molecules indicate that their conformations are only slightly different from that of gramicidin A in conformation I.     

Low serum testosterone concentrations in patients with carcinoma of the pancreas

The detection of high activities of two sex-steroid biosynthetic enzymes—aromatase and 5-alpha-reductase—in pancreatic carcinoma tissue suggested the possibility that these enzymes may influence the circulating concentrations of sex-steroid hormones. Mean serum testosterone concentrations in 22 men and women with exocrine carcinoma of the pancreas were significantly lower than those in 20 healthy controls and 27 patients with other known malignancies, who were of similar age and sex composition. Low serum testosterone concentrations may be due to uptake by and metabolism within the tumour; alternatively, patients with low androgen concentrations may be at greater risk of developing pancreatic carcinoma.     

Aggregation of apolar peptides in organic solvents. Concentration dependence of 1H-nmr parameters for peptide NH groups in 310 helical decapeptide fragment of suzukacillin

Peptide NH chemical shifts and their temperature dependences have been monitored as a function of concentration for the decapeptide, Boc-Aib-Pro-Val-Aib-Val-Ala-Aib-Ala-Aib-Aib-OMe in CDCl₃ (0.001–0.06M) and (CD₃)₂SO (0.001–0.03M). The chemical shifts and temperature coefficients for all nine NH groups show no significant concentration dependence in (CD₃)₂SO. Seven NH groups yield low values of temperature coefficients over the entire range, while one yields an intermediate value. In CDCl₃, the Aib(1) NH group shows a large concentration dependence of both chemical shift and temperature coefficient, in contrast to the other eight NH groups. The data suggest that in (CD₃)₂SO, the peptide adopts a 3₁₀ helical conformation and is monomeric over the entire concentration range. In CDCl₃, the 3₁₀ helical peptide associates at a concentration of 0.01M, with the Aib(1) NH involved in an intermolecular hydrogen bond. Association does not disrupt the intramolecular hydrogen-bonding pattern in the decapeptide.     

中国吻额蛛属一新种（蜘蛛目：皿蛛科：微蛛亚科）

本文描述了作者1986年采自湖北省神农架林区的吻额蛛属Aprifrontalia一新种:膨大吻额蛛,新种Aprifrontalia afflata sp.nov.。目前,除本新种外,世界仅报道过1种:Aprifrontalia mascula,本新种雄蛛最显著的特征是:其额向前突呈吻状,触肢胫节前端甚膨大。外雌器形成一斜向下方的突起。模式标本保存于白求恩医科大学生物教研室。     

幼年大鼠诱发排卵条件下卵巢前列腺素(PGs)的含量变化及其生理作用

本实验用幼年大鼠经PMSG/hCG诱发排卵,研究了印巢PGE_2、PGF_(2α) 、6-酮-PGF_(1α) 及TXB_2在排卵过程中的变化。实验表明卵巢PGE_2、PGF_(2α) 及6-酮-PGF_(1α) 在排卵前达到峰值,在排卵后,均趋下降。TXB_2未出现明显变化。受试动物经消炎痛处理后,不仅使排卵受到严重抑制,而对上述三种PGs在排卵前的上升也表现了显著的抑制。提示在卵泡破裂过程中PGs的重要调节作用,PGE_2、PGF_(2α)均可能参与排卵,其中尤以PGE_2的作用最为显著。