Effect of cortisol on the metabolism of 17-hydroxyprogesterone by Arctic charr and rainbow trout embryos

The effect of cortisol on the in vitro metabolism of [³H]17-hydroxyprogesterone ([³H]17OHP) was studied during embryonic development of Arctic charr (Salvelinus alpinus) and rainbow trout (Oncorhynchus mykiss). In the absence of cortisol, rainbow trout embryos metabolized [³H]17OHP largely to androstenedione (A₄) and androstenetrione (11-KA) with a minor conversion to 17,20ß-dihydroxy-4-pregnen-3-one (17,20P). In the presence of cortisol, this biosynthesis was inhibited. On the other hand, cortisol had no apparent inhibitory effect on the nature of metabolism of [³H]17OHP by Arctic charr embryos. In these embryos [³H]17OHP was metabolized mainly to 17,20P with a minor conversion to A₄ and without the formation of 11-KA that was seen in rainbow trout.When incubated in the presence of [³H]cortisol both Arctic charr and rainbow trout embryos produced 11ß-hydroxyandrostenedione (11ß-OHA) as the major metabolite, with a minor conversion to an unknown steroid. The catabolism of the cortisol by salmonid embryos may reflect the ability of the embryo to inactivate or detoxify cortisol to protect itself from the adverse effects of this biologically potent steroid hormone The study indicates the existence of species-specific differences in the nature of metabolism of [³H]17OHP and the inhibitory effect of cortisol on this metabolism.     

Evidence that 17α,20β,21-trihydroxy-4-pregnen-3-one is a maturation-inducing steroid in spotted seatrout

Ovarian steroidogenesis during final oocyte maturation (FOM) in the spotted seatrout (Cynoscion nebulosus) was investigated by incubating ovarian fragments with tritiated pregnenolone, followed by chromatographic separation of the radioactive products. The major tritiated steroid produced during FOM comigrated with 17α,20β,21-trihydroxy-4-pregnen-3-one (20β-dihydro-11-deoxycortisol, 20β-S) on HPLC and TLC. Only minor amounts of radioactive material coeluted with 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-P), 11-deoxycorticosterone (DOC), estradiol-17β and testosterone standards in the HPLC system. Additional chromatography by TLC confirmed the presence of radioactive estradiol-17β and testosterone but not 17α,20β-P and DOC. All the ovarian steroids producedin vitro during FOM were assayed for their ability to induce germinal vesicle breakdown (GVBD) of spotted seatrout oocytes. Twenty grams of ovarian tissue were incubated with human chorionic gonadotropin and exogenous pregnenolone. The steroidal products were purified by HPLC and TLC. Most of the maturation-inducing activity was confined to steroidal material which comigrated in these systems with 20β-S. This material was active at a concentration of 1 ng steroid/ml medium in the GVBD assay. Smaller amounts of material which coeluted with 11-deoxycortisol, DOC, 17α,20β-P and several minor unidentified fractions induced GVBD at concentrations of 10 ng steroid(s)/ml. The structure-activity relationships of authentic steroids in inducing GVBD of spotted seatrout oocytes was investigated. Hydroxylation at the 17α, 20β or 21 positions increased potency to induce GVBD. Steroids with multiple hydroxyl groups at the 17α and 20β positions (17α, 20β-P) and at the 17α, 20β, and 21 positions (20β-S) had maximum biological activity in the GVBD bioassay. The results suggest that 20β-S is a major maturation-inducing steroid in spotted seatrout.     

Control of ion transport by the sperm duct epithelium of brook trout (Salvelinus fontinalis)

The sperm duct epithelium of brook trout (Salvelinus fontinalis), mountedin vitro in Ussing-style epithelial chambers actively absorbs Na⁺ (measured as the short-circuit current, I_sc) and secretes K⁺ (measured using⁸⁶Rb⁺ as tracer). Dibutyryl-cyclic-adenosine monophosphate (db-cAMP) and 3-isobutyl-1-methylxanthine (IMX) produce a rapid, sustained stimulation of both ion transport processes, but the hormone connected to the response is unknown. Purified sockeye salmon CON A2 gonadotropin (GtH) produces a dose-dependent, rapid and sustained rise in Na⁺ uptake and K⁺ secretion. The time course, electrophysiological and transport characteristics are similar to those evoked by IMX. Carbohydrate-poor (chum salmon CON A1) GtH is ineffective. Pretreatment of fish with 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-P) significantly increases milt volume but is without effect on resting or stimulated (IMX + db-cAMP) levels of sperm duct ion transport. This is the first indication of a direct, rapid action of GtH on ion transport by the vertebrate blood-testis barrier. The results suggest direct involvement of GtH in control of later stages of sperm maturation.     

优质高产抗病西瓜新品种‘荆杂20’的选育

‘荆杂20’是以优良稳定自交系‘87005’为母本、抗病稳定自交系‘2084’为父本杂交育成的中大果型中熟有籽西瓜品种。全生育期100¹10 d,果实发育32 d左右。果实圆形,果皮底色脆绿,覆墨绿较规则细条带。红瓤,瓤色均匀,质地细脆多汁,籽较少,不易空心,中心可溶性固形物含量12%左右,边部含量8%110 d,果实发育32 d左右。果实圆形,果皮底色脆绿,覆墨绿较规则细条带。红瓤,瓤色均匀,质地细脆多汁,籽较少,不易空心,中心可溶性固形物含量12%左右,边部含量8%⁹%。皮厚1.0 cm左右,果皮坚硬不易裂果,耐贮藏,商品率高。一般单果质量59%。皮厚1.0 cm左右,果皮坚硬不易裂果,耐贮藏,商品率高。一般单果质量5⁸ kg,667 m2产量4 000 kg左右。该品种生长势强,易坐果,抗枯萎病、产量高、品质优、易栽培,适合全国多地栽培。参加了2011—2012年湖北省西瓜品种区域试验,2014年通过湖北省品种审定。     

Circulating levels and in vitro production of two maturation-inducing hormones in teleost: 17α,20β-dihydroxy-4-pregnen-3-one and 17α,20β,21-trihydroxy-4-pregnen-3-one, in a daily spawning wrasse, Pseudolabrus japonicus

The female bambooleaf wrasse, Pseudolabrus japonicus, spawns daily during the spawning season, and exhibits a diurnal rhythm of ovarian development. In the present study, we have investigated: (1) circulating levels of 17a, 20-dihydroxy-4-pregnen- 17,20-P) and 17,20,21-trihydroxy-4-pregnen-3-one (20-S) in females sampled at different times of the day during spawning season in captivity, and (2) in vitro production of 17,20-P and 20-S by follicle-enclosed oocytes at seven different develo tal stages. In addition, we developed a microtiter plate enzyme-linked immunosorbent assay (ELISA) for 17,20-P. Serum levels of 17,20-P and 20-S showed similar diurnal changes; substantial increases in these levels occurred around the time of germinal vesicle breakdown (GVBD). In vitro experiments showed that massive production of 17,20-P and 20-S occurred in follicles collected just before or during GVBD. Further, acute decreases in 17,20-P and 20-S production were found in the ovarian follicles just prior to ovulation, suggesting inactivation of the maturation-inducing hormone (MIH). These results, taken together with our previous data on the occurrence of GVBD in vitro, suggest a role for both 17,20-P and 20b-S as MIHs in the bambooleaf wrasse.     

Effect of Biogas Digested Liquid on OH4 and N2O Flux in Paddy Ecosystem

Biogas production generates digested slurry as a byproduct. It can be used as a fertilizer especially after its conversion into digested liquid. A pot based study was conducted in order to evaluate the effect of the application of digested liquid on CH4 and N2O flux, and plant biomass in paddy. Analysis revealed that digested liquid treated soils released more CH4 compared to ammonium sulphate and the control. Ammonium sulphate treated soil emitted the highest N20 whereas digested liquid application decreased its emission significantly. Further, the cumulative emission over 101 d of the experiment was found to be higher for CHa （16.9 to 29.9 g m^-2） compared to N20 （-49.3 to 18.9 mg m^-2） for all treatments. Digested liquid application had positive impact on plant variables such as panicle number and weight of panicles. This study suggests that digested liquid application significantly decrease N20 emission and increase CH4 emission possibly due to affecting the availability of organic C in the soil to microbial activity for methanogenesis. Another possibility for enhancing CH4 emission by following biogas digested liquid could be attributed to the increase in plant biomass.     

Binding characteristics and regulation of the 17,20β,21-trihydroxy-4-pregnen-3-one (20β-S) receptor on testicular and sperm plasma membranes of spotted seatrout (Cynoscion nebulosus)

The binding characteristics of 17,20,21-trihydroxy-4-pregnen-3-one (20-S) to plasma membranes prepared from the testes and sperm of spotted seatrout (Cynoscion nebulosus) were investigated using a filtration method to retain the bound 20-S. A single class of high affinity (K_d = 17.9 nM), low capacity (B_max = 0.072 nM g^-1 testes) binding sites was identified by saturation and Scatchard analyses on testicular membranes of spermiating spotted seatrout. A corresponding receptor (K_d = 22.17 nM, B_max = 0.00261 nM ml^-1 milt) was also detected in spermatozoan membrane preparations. The rates of 20-S association and dissociation were rapid, both had T_halfs of less than 1 min. Competition studies indicated that the receptor was highly specific for 20-S. 17,20-dihydroxy-4-pregnen-3-one, which had the highest affinity of the other steroids tested, had a relative binding affinity (RBA) of 14.3%. Progesterone, 11-deoxycortisol and testosterone competed with an order of magnitude less affinity (RBA's of 7.4, 1.8 and 1.1%, respectively). Estradiol displayed low affinity for the receptor (RBA = 0.4%) and cortisol did not cause any displacement at 1000-fold excess concentration. Specific 20-S receptor binding was detected in plasma membranes from testes of both spermiating and non-spermiating seatrout and on spermatozoa. Prolonged incubation of testicular fragments from a spermiating fish with gonadotropin (15 IU ml^-1 human chorionic gonadotropin) or forskolin (10 µM) caused a 2–3 fold increase in membrane receptor binding. Previous studies have shown that gonadotropin-induced upregulation of the 20-S plasma membrane receptor in seatrout ovaries is required for the oocytes to become responsive to 20-S and undergo final maturation. The existence of a 20-S membrane receptor on sperm and its upregulation in the testes by gonadotropin raises the possibility that final maturation of spermatozoa in male seatrout may be regulated by a similar mechanism.     

对获取IMA部件认可信件的适航审定要求分析

综合模块化航电系统(IMA)可以采用增量认可形式,分不同任务开展IMA适航取证工作。增量认可过程中,可以通过认可信件的形式获取批准。本文结合适用于IMA系统适航审定相关文件,总结出获取IMA部件认可信件的相关要求和申请过程介绍。本研究可为我国民用飞机IMA系统的适航审定工作提供理论基础。     

二种不同养殖模式的病害防治技术的对照试验

采用 8 0∶2 0养殖鮰鱼与传统主养鮰鱼夏花鱼种的病害防治技术 ,在 1、2号池塘中对照试验 ,在同等条件下 ,1号试验塘斑点叉尾鮰的成活率为 81.3%。     

Gram-negative bacterial flora on the root surface of wheat (Triticum aestivum) grown under different soil conditions

We identified 161 Gram-negative bacterial strains isolated from the root surface of wheat grown under different soil conditions. The strains were divided into seven groups based on major morphological and physiological properties. Taxonomic allocation of the groups was verified by guanine+cytosine contents of DNA. Except for one group, which may be assumed to include bacteria belonging to the genera Flavobacterium and Cytophaga, the various groups were taxonomically united. The distribution of the groups changed with soil improvement. Pseudomonads predominated in unimproved soil, but Flavobacterium and Cytophaga spp. were predominant in the most improved soil. As all the strains were non-fermentative by Hugh and Leifson's test, API 20NE identification was applied. However, many strains were misidentified by this system, especially in the Flavobacterium and Cytophaga spp. group. For ecological studies, the strains were classified to species level by the API 20 NE system and by the results of a combination of guanine+cytosine (mol%) and isoprenoid quinone data. The pattern of distribution of the bacteria on the root surface of wheat varied at species level within one genus depending on soil conditions.Dedicated to Professor J. C. G. Ottow on the occasion of his 60th birthday