The inhibitory action of corticotropin-releasing hormone on gonadotropin secretion in the ovariectomized rhesus monkey is not mediated by adrenocorticotropic hormone

Earlier observations in our laboratory indicated that i.v. infusion of human/rat corticotropin-releasing hormone (hCRH) suppresses pulsatile luteinizing hormone (LH) and follicle-stimulating hormone (FSH) release in ovariectomized rhesus monkeys. Since cortisol secretion increased significantly as well, it was not possible to exclude the possibility that this inhibitory effect of hCRH on gonadotropins was related to the activation of the pituitary/adrenal axis. The purpose of the present study was to determine the role of pituitary/adrenal activation in the effect of hCRH on LH and FSH secretion. We compared the effects of 5-h i.v. infusions of hCRH (100 micrograms/h, n = 7) and of human adrenocorticotropic hormone (ACTH) (1-24) (5 micrograms/h, n = 3; 10 micrograms/h, n = 3, 20 micrograms/h, n = 3) to ovariectomized monkeys on LH, FSH, and cortisol secretion. As expected, during the 5-h ACTH infusions, cortisol levels increased by 176-215% of baseline control, an increase similar to that observed after CRH infusion (184%). However, in contrast to the inhibitory effect observed during the CRH infusion, LH and FSH continued to be released in a pulsatile fashion during the ACTH infusions, and no decreases in gonadotropin secretion were observed. The results indicated that increases in ACTH and cortisol did not affect LH and FSH secretion and allowed us to conclude that the rapid inhibitory effect of CRH on LH and FSH pulsatile release was not mediated by activation of the pituitary/adrenal axis.     

Transforming growth factor beta regulates the inhibitory actions of epidermal growth factor during granulosa cell differentiation

The effects of transforming growth factor beta (TGF-beta) on epidermal growth factor (EGF) receptor content and EGF action were studied in cultured granulosa cells from immature diethylstilbestrol-implanted rats. During follicle-stimulating hormone (FSH)-induced differentiation in vitro, EGF receptors increased by 20-fold as measured by the binding of 125I-EGF to the intact cells. Addition of TGF-beta during the 48-h culture period amplified the stimulatory effects of FSH on EGF receptors up to 2-fold, with ED50 and maximal concentrations of 2.5 and 8 pM, respectively. Also TGF-beta alone in amounts from 1.6 to 16 pM increased EGF receptor content 4-fold. The stimulatory effects of TGF-beta were due to increased numbers of EGF receptors/cell, since the growth factor had no effect on the Kd (3-5 X 10(-11) M) of the high-affinity EGF binding site. TGF-beta action was observed within 20 h of granulosa cell culture and was maximal by 48 h of a 96-h culture. The stimulatory actions of TGF-beta in gonadotropin-induced cells were exerted through the cAMP effector system of the granulosa cell, since the growth factor also amplified the induction of EGF receptors by cholera toxin, forskolin, and 8-bromo-cAMP. The augmentation of EGF receptors by TGF-beta resulted in a parallel 2-fold increase in the inhibitory effects of EGF on FSH-induced cAMP production and luteinizing hormone receptor expression during granulosa cell development. TGF-beta did not increase granulosa cell numbers during culture although it elevated [3H]thymidine incorporation into DNA by 2-fold over that of FSH-treated cells. These results indicate that TGF-beta regulates the effects of both FSH and EGF during granulosa cell differentiation and provides evidence that ovarian function may be controlled by the combined actions of gonadotropins and multiple growth factors.     

慢性蜜蜂麻痹病病毒核酸与蛋白质组分的研究

从自然感染的意大利麻痹病蜂(APis mellifera)头部,经二次差速离心与蔗糖梯度离心获得纯化的慢性蜜蜂麻痹病病毒(CBPV)。纯化的CBPV制备物感染正常蜜蜂,4天后出现典型的麻痹症状,接着死亡,平均死亡率分别为95％与100％。SDS-聚丙烯酰胺凝胶电泳分析,二次差速离心初步纯化的病毒制备物含有多条蛋白带,而蔗糖密度梯度纯化的病毒制备物仅含有单一的多肽带。5％、7.5％与10％SDS-聚丙烯酰胺凝胶电泳分析,均检测出一种病毒蛋白质,分子量大约为24,200道尔顿,而且不同凝胶浓度检测的蛋白质分子量相近。慢性蜜蜂麻痹病病毒核酸也用SDS-聚丙烯酰胺凝胶电泳分析,结果表明,凝胶中有5条带,对核酸酶敏感,证明该病毒含有5个单股RNA组分。对慢性蜜蜂麻痹病病毒的基因组结构进行了讨论。     

呼吸链底物和抑制剂对线粒体内膜流动性的影响

用DPH和ANS标记大鼠肝线粒体内膜,以稳态荧光偏振法,研究了呼吸链底物和抑制剂对内膜流动性的影响。1.苹果酸+谷氨酸、琥珀酸分别为底物,均能引起内膜流动性增加。2.琥珀酸对含心磷脂的脂质体的膜流动性无影响。3.在鱼藤酮存在的条件下,苹果酸+谷氨酸对内膜流动性的增加作用消失,但琥珀酸的作用仍然存在。有氰化钾时则琥珀酸的作用消失。4.不论外加底物存在与否,鱼藤酮使内膜的流动性下降,而氰化钾则使之增加。抗霉素A亦可使内膜的流动性增加。上述结果表明:线粒体内膜流动性与其功能密切相关。电子沿呼吸链传递使线粒体内膜流动性增加,这种变化可能与呼吸链成分的氧化还原态有关。     

Combinations of palytoxin or 12-O-tetradecanoylphorbol-13-acetate and recombinant human insulin growth factor-I or insulin synergistically stimulate prostaglandin production in cultured rat liver cells and squirrel monkey aorta smooth muscle cells

In the presence of 12-O-tetradecanoylphorbol-13-acetate (TPA) or the non-TPA-type tumor promoter, palytoxin, recombinant human insulin growth factor-I (IGF-I) and insulin synergistically stimulate prostaglandin production in rat liver cells (the C-9 cell line). Combinations fo palytoxin or TPA with recombinant human IGF-I or insulin also synergistically stimulate deesterification of c ellular lipids in C-9 cells prelabelled with [³H]arachidonic acid. With both types of stimulations, prostaglandin production or deesterification, the synergistic response of the IGF-I and insulin is greater with palytoxin than with TPA. Production of prostaglandin E₂ and F_2α by squirrel monkey smooth muscle cells incubated in the presence of TPA and insulin also is greater than the sum of the effects taken independently.     

An HRP-study of the frequency-place map of the horseshoe bat cochlea: Morphological correlates of the sharp tuning to a narrow frequency band

Summary The frequency-place map of the horseshoe bat cochlea was studied with the horseradish peroxidase (HRP) technique involving focal injections into various, physiologically defined regions of cochlear nucleus (CN). The locations of labeled spiral ganglion cells and their termination sites on inner hair cells of the organ of Corti from injections into CN-regions responsive to different frequencies were analyzed in three dimensional reconstructions of the cochlea. Horseshoe bats from different geographical populations were investigated. They emit orientation calls with constant frequency (CF) components around 77 kHz (Rhinolophus rouxi from Ceylon) and 84 kHz (Rhinolophus rouxi from India) and their auditory systems are sharply tuned to the respective CF-components.The HRP-map shows that in both populations: (i) the frequency range around the CF-component of the echolocation signal is processed in the second half-turn of the cochlea, where basilar membrane (BM) is not thickened, secondary spiral lamina (LSS) is still present and innervation density is maximal; (ii) frequencies more than 5 kHz above the CF-component are processed in the first halfturn, where the thickened BM is accompanied by LSS and innervation density is low; (iii) frequencies below the spectral content of the orientation call are represented in apical turns showing no morphological specializations. The data demonstrate that the cochlea of horseshoe bats is normalized to the frequency of the individual specific CF-component of the echolocation call.The HRP-map can account for the overrepresentation of neurons sharply tuned to the CF-signal found in the central auditory system. A comparison of the HRP-map with a map derived with the swollen nuclei technique following loud sound exposure (Bruns 1976b) reveals that the latter is shifted towards cochlear base by about 4 mm. This discrepancy warrants a new interpretation of the functional role of specialized morphological structures of the cochlea within the mechanisms giving rise to the exceptionally high frequency selectivity of the auditory system.Abbreviations AVCN anteroventral CN - BF best frequency - BM basilar membrane - CF constant frequency - CN cochlear nucleus - DCN dorsal CN - FM frequency modulated - HRP horseradish peroxidase - IHC inner hair cell - LSS secondary spiral lamina - OHC outer hair cell - PVCN posteroventral CN - RF resting frequency - RRc Rhinolophus rouxi from Ceylon - RRi Rhinolophus rouxi from India     

花椰菜(Brassica oleracea var botrytis)下胚轴培养过程中过氧化物酶活性及同工酶谱的变化

花椰菜下胚轴外植体在MS+6BA 5 ppm的培养基上能分化出芽,在MS+2,4-D2ppm的培养基上能脱分化而形成愈伤组织。用3种不同的酚类物质(咖啡酸、阿魏酸、愈创木酚及联苯胺)作氢供体发现分化过程中的过氧化物酶活性高于脱分化过程,其中以咖啡酸作氢供体显示的活性最高,阿魏酸及愈创木酚次之,而联苯胺最小。用聚丙烯酰胺凝胶电泳分离阴极向及阳极向过氧化物酶同工酶,在分化及脱分化培养过程中均不断出现新的酶带,前者有13条,后者为11条,两者的差别主要在阴极向酶带,在分化过程中多了两条酶带(C_1和C_3),同时C_2带活性也比脱分化的高。阳极向酶带也有差别,A_2和A_2两条酶带在分化过程中逐渐加强,但是在脱分化过程中却逐渐消失。反映了两个过程生理上的差别。