Preparation of 2,3-seco-5 alpha-cholestane-2,3-diol and 4 alpha-methyl-2,3-seco-5 alpha-cholestane-2,3-diol and its reactions with o-nitrophenyl selenocyanate

The reaction of 2,3-seco-5 alpha-cholestane-2,3-diol and 4 alpha-methyl-2,3-seco-5 alpha-cholestane-2,3-diol with o-nitrophenyl selenocyanate was studied. The diols were synthesized from cholesterol.     

Current distribution and potential expansion of the harmful benthic dinoflagellate Ostreopsis cf. siamensis towards the warming waters of the Bay of Biscay,North-East Atlantic

In a future scenario of increasing temperatures in North-Atlantic waters, the risk associated with the expansion of the harmful, benthic dinoflagellate Ostreopsis cf. siamensis has to be evaluated and monitored. Microscopy observations and spatio-temporal surveys of environmental DNA (eDNA) were associated with Lagrangian particle dispersal simulations to: (i) establish the current colonization of the species in the Bay of Biscay, (ii) assess the spatial connectivity among sampling zones that explain this distribution, and (iii) identify the sentinel zones to monitor future expansion. Throughout a sampling campaign carried out in August to September 2018, microscope analysis showed that the species develops in the south-east of the bay where optimal temperatures foster blooms. Quantitative PCR analyses revealed its presence across almost the whole bay to the western English Channel. An eDNA time-series collected on plastic samplers showed that the species occurs in the bay from April to September. Due to the water circulation, colonization of the whole bay from the southern blooming zones is explained by inter-site connectivity. Key areas in the middle of the bay permit continuous dispersal connectivity towards the north. These key areas are proposed as sentinel zones to monitor O. cf. siamensis invasions towards the presumably warming water of the North-East Atlantic.     

Substances Isolated from Woody Cuttings of Salix atrocinerea and Their Growth Properties

A study of the cuttings of Salix atrocinerea Brot. was made by extraction with methanol, paper chromatography and Avena coleoptile straight growth test. In the acidic fraction, indole-3-acetic acid (IAA; about 15 μg per kg fresh weight) and p-hydroxybenzoic acid (PHB; about 850 μg per kg fresh weight) were isolated and identified. The growth activity of the different zones is explained by their content of these two compounds. The watersoluble residue, insoluble in ether, showed growth Stimulating activity, which probably is due to a bound auxin (IAA-sugar); alkaline breakdown of this aqueous residue, giving PHB, vanillic and p-coumaric acids, suggests the presence (in the cuttings of Salix atrocinerea) of glycosides with aglycones similar to rhamnacine and scutellareine.     

Multiple antibiotic susceptibility associated with inactivation of the prc gene.

A Tn5 insertion which led to increased susceptibility to multiple drugs, including tetracycline, chloramphenicol, nalidixic acid, erythromycin, spectinomycin, norfloxacin, and novobiocin, was identified in Escherichia coli. Cloning and sequence studies showed that the insertion was in the previously identified prc gene at min 40.4. The prc product is known to function as a protease linked to processing of penicillin-binding protein 3 and lambda repressor and when absent to allow some leakage of periplasmic constituents. Complementation studies with the prc gene on plasmids showed complete recovery of parental levels of susceptibility to all drugs except chloramphenicol, with which only partial reversion to wild-type levels was observed.     

基于改进三维生态足迹模型的洞庭湖区生态可持续时空演化研究

洞庭湖是长江流域重要的调蓄湖泊，也是中国重要的农产品主产区。科学评估洞庭湖区生态可持续状态，揭示其时空演化特征，对探究其生态可持续影响因素与作用机理，降低生态赤字具有重要意义。基于碳足迹与生态足迹理论构建了改进的三维生态足迹模型，填补了化石能源无法核算生态承载力的问题，同时调整了不同土地利用类型的参数因子。在对洞庭湖区25个区县进行可持续发展的动态评价分析中，计算了2000—2019年生态赤字、足迹广度与深度的时空分布特征。研究结果表明：(1)近20年来洞庭湖区的人均生态足迹增长速度远高于人均生态承载力，致使人均生态赤字在时间维度上不断增大，空间维度上呈湖滨向周边地区扩散的趋势；(2)洞庭湖区除林地之外的土地利用类型均存在自然资本存量的消耗，且表现为高生态赤字；(3)三次产业结构的分配、土地利用的变化、居民对生活质量的提高以及生态保护政策的有效实施等均会对洞庭湖区的可持续发展产生较大影响；(4)改进后的化石能源账户相较于传统账户的计算方法更能反映真实的碳排量与碳吸收量。研究以期为洞庭湖区土地利用、生态保护以及促进社会经济可持续发展提供科学参考。     

Effects of intrahypothalamic injections of GABA, muscimol, pentobarbital, and L-glutamic acid on feed intake of satiated sheep

Five wethers were surgically prepared with cranial implants to study the role of gabaminergic neural pathways on the hypothalamic control of feeding behaviour in ruminants. In the first experiment, the animals were injected (1 microL) with a physiological Tyrode (0.95%) solution, muscimol (0.5 and 1.0 nmol), GABA (0.5 and 1.0 nmol), and L-glutamic acid (0.5 and 1.0 nmol). Feed intake following injections of muscimol (1.0 nmol) and L-glutamic acid (0.5 and 1.0 nmol) was twice as large as that following the Tyrode solution, at 60-min postinjections. These results, however, were not statistically significant (p = 0.12-0.15). In the second experiment, the animals were injected (1 microL) with saline, muscimol (0.8 nmol), L-glutamic acid (0.8 nmol), and pentobarbital (0.26 mumol). Fifteen minutes after the injections, pentobarbital had induced a significant feeding response when compared with control values (p less than 0.01), whereas the effect of L-glutamic acid was not significant. However, 30 min after the injections, feed intake of sheep having received L-glutamic acid was higher than that obtained with the control injections (p less than 0.01). The response to pentobarbital was stronger than that to either muscimol or L-glutamic acid. Histological analyses of brain tissue indicated that injections were performed in the ventromedial hypothalamus of four sheep and in the dorsomedial hypothalamus of the other. The data indicate that L-glutamic acid stimulates feed intake by acting either as a precursor of GABA or by a direct stimulation of glutaminergic neural pathways involved in the control of feed intake.     

Ultrastructural and immunocytochemical evidences of core-particle formation in the methylotrophic Pichia pastoris yeast when expressing HCV structural proteins (core-E1).

Particulate antigens of the Hepatitis C virus (HCV) are reported for the first time by transmission electron microscopy in Pichia pastoris. The yeast was cloned to express the first 339 NH2-terminal amino acids of the HCV polyprotein (C-E1.339 polypeptide). The C-E1.339 polypeptide covers the putative 191 aa of the core protein (aa 1-191) and 148 aa of the E1 envelope antigen (aa 192-339). Virus-like particles (VLP) with diameters ranging from 20 nm to 30 nm were specifically observed in those cells expressing the HCV polyprotein. The VLP appeared along the membrane of the endoplasmic reticulum, but were fundamentally localized in vacuoles, either free or inside autophagic bodies. Clustered particles, chains of particles, high-density reticular structures, and crystalloid bodies were also detected, the last one being an orderly arrangement of particles with 20 nm diameters. The crystal-associated particles are well differentiated from the intracellular VLP because of their uniform size and shape. We argue that membrane components are retained in the architecture of the VLP, conferring to this particle certain heterogeneity. Both kinds of particles, the VLP formed after treatment with NP-40 and the crystal-associated particles, were core protein-positives. Whether they reflect mature HCV nucleocapsid or intermediary states in the viral nucleocapsid morphogenesis remains unknown. We conclude that, like mammalian cell lines, the P. pastoris yeast could be an appropriate host for the analysis of HCV polyprotein processing and, eventually, virus assembly.