Calvatia sporocristata sp. nov. (Gasteromycetes) from Costa Rica

Calvatia sporocristata, Gasteromycetes, is described and illustrated as a new species. Its taxonomic characters are discussed and compared with other closely related species of the genus. Few studies have been carried out on tropical Gasteromycetes. The new species here proposed has, as the main features: exoperidium corky, smooth, one-layered, pseudoparenchymatous; endoperidium thin, papyraceous, dextrinoid; subgleba cellular; capillitium septate, dissociated at the septal site, lycoperdon type, without pores, elastic and spores amigdaloid, 4-6 (-7) x 2.5-4.5 microns with spines aligned, forming crests, 0.8 micron high.     

In Vitro susceptibility of 137 Candida sp. Isolates from HIV positive patients to several antifungal drugs

Oropharyngeal candidiasis caused by various species of Candida is one of the most common infections in HIV seropositive or AIDS patients. Drug resistance among these yeasts is an increasing problem. We studied the frequency of resistance profile to fluconazole, itraconazole, ketoconazole, amphotericin B and terbinafine of 137 isolates of Candida sp. From HIV positive or AIDS patients with oropharyngeal candidiasis at Instituto de Inmunología, U.C.V. and the Hospital “Jose Ignacio Baldó”, Caracas Venezuela, using the well diffusion susceptibility test (Magaldi et al.). We found that nearly 10% of C. albicans isolates were primarily fluconazole resistant, 45% of C. albicans isolates from patients with previous treatment were resistant to fluconazole, of which 93% showed cross-resistance to itraconazole, and even about 30% of C. tropicalis (n = 13) were resistant to fluconazole and/or itraconazole. To this respect, several recent reports have been described antifungal cross-resistance among azoles. Therefore, we consider that C. tropicalis should be added to the growing list of yeast in which antifungal drug resistance is common. This report could be useful for therapeutic aspect in AIDS patients with oral candidiasis. This revised version was published online in July 2006 with corrections to the Cover Date.     

Microbial study of farmhouse ewe cheese during storage in olive oil

The effect of storing farmhouse ewe cheese in oil and in vacuo over long periods of time on physicochemical properties (water activity and pH) and the microbiota of the cheese was investigated. The storage conditions were found to scarcely influence the sample pH. Also, the initial water activity (a(w) = 0.961) and its value after 9 months of storage (0.927) were both very similar to those for naturally ripened cheese. The incidence of pathogenic microbial groups was found to decrease with storage time (counts fell below 1 log CFU/g). The flora that effects proteolytic changes in cheese consisted of lactic microorganisms (viz. lactococci and lactobacilli), in addition, after 6 months of storage, of enterococci. The last are responsible for the formation of large amounts of soluble nitrogen (SN), non-protein nitrogen (NPN) and aminoacid nitrogen (NH2-N), which provide this type of cheese with very special sensory features while preventing dehydration and thus lengthening its shelf life.     

Substrate specificities and 13-cis-retinoic acid inhibition of human, mouse and bovine cis-retinol dehydrogenases

Recent studies of the human, mouse and bovine genes for 11-cis-retinol dehydrogenase (11cRDH) and human and mouse 9-cis-retinol dehydrogenase (9cRDH) suggest that they are homologs of the same enzyme. This conclusion is inconsistent with earlier literature indicating that 11cRDH is expressed solely in the eye and does not utilize 9-cis-retinol as a substrate. We have compared directly the kinetic properties of recombinant human and mouse 9cRDH with those of bovine 11cRDH for 9-cis- and 11-cis-retinol and investigated the inhibitory properties of 13-cis-retinoic acid on each of these enzymes. Human and mouse 9cRDH and bovine 11cRDH have very similar kinetic properties towards 9-cis- and 11-cis-retinol oxidation and they respond identically to 13-cis-retinoic acid inhibition. Our biochemical data are consistent with the conclusion that 9cRDH and 11cRDH are the same enzyme.     

Topology and transport of membrane lipids in bacteria

The last two decades have witnessed a break-through in identifying and understanding the functions of both the proteins and lipids of bacterial membranes. This development was parallelled by increasing insights into the biogenesis, topology, transport and sorting of membrane proteins. However, progress in research on the membrane distribution and transport of lipids in bacteria has been slow in that period. The development of novel biochemical in vitro approaches and recent genetic studies have increased our understanding of these subjects. The aim of this review is to present an overview of the current knowledge of the distribution and transport of lipids in both Gram-positive and Gram-negative bacteria. Special attention is paid to recently obtained results, which are expected to inspire further research to finally unravel these poorly understood phenomena.     

Evaluation of the effect of cryopreservation of Pleurotus spp. strains on carpophore production.

The effect of the cryopreservation of six Pleurotus strains was evaluated. Primordia initiation, number of flushes, biological efficiency and fruiting body size obtained with respect to pileus diameter was recorded. These strains were previously evaluated before storage in liquid nitrogen. Variation in the number of flushes (3-4), the fruiting body size (< 5 cm at > 15 cm) and biological efficiency was observed. This varied according to the strain used, ranging from 55-105.6%. The fruiting bodies of the cryopreserved strains did not differ with respect to the untreated strains.     

根黄酮在植物生长和营养中的作用

 本文简要综述了80年代以来国际上对根黄酮在调节植物根生长、完善根功能、影响氮素循环及在施加他感作用方面的研究进展,并对有关方面作了一些展望,以期引起植物营养工作者对植物次生物质的注意。     

鄂西南五种野生荚蒾属植物种群结构与动态特征研究

为探明鄂西南地区野生荚蒾属(Viburnum)植物的种群数量特征及区域分布状况，并揭示宜昌荚蒾(V.erosum)、桦叶荚蒾(V.betulifolium)、合轴荚蒾(V.sympodiale)、茶荚蒾(V.setigerum)、荚蒾(V.dilatatum)5种荚蒾属植物种群的生存现状及发展趋势，在鄂西南金子山国有林场、木林子国家级自然保护区及七姊妹山国家级自然保护区，共布设27 hm²固定动态监测样地对荚蒾属植物进行调查，通过对5种荚蒾属植物种群进行年龄结构、动态量化分析和静态生命表以及相关曲线等研究，探讨荚蒾属植物种群结构与动态特征及未来发展潜力。结果表明：(1)鄂西南荚蒾属植物在分布区域及种群数量大小上均存在明显差异。(2)种群结构与动态分析显示，5种荚蒾属植物种群年龄结构呈现为金字塔型，幼龄阶段种群个体数量较多，具有较强的增长潜力，但对外界干扰均具有较强的敏感性。(3)静态生命表显示，5种荚蒾属植物存活量均随着龄级的增加而单调递减；消失率与死亡率曲线变化趋势相似，但不同植物消失率与死亡率曲线波动具有差异性；种群存活曲线均趋近于Deevey-Ⅱ型。(4)4...     

HBV pre-c-Fc融合蛋白在杆状病毒表达系统中的表达及其生物学活性研究

目的:在杆状病毒表达系统中表达融合蛋白乙型肝炎病毒前C蛋白-小鼠IgG Fc蛋白(HBV precore protein-mouse IgG Fc,HBV pre-c-Fc),并鉴定其免疫原性。方法:目的基因HBV prec-Fc连接到pFastBac1载体,获得的pFastBac1-HBV pre-c-Fc质粒转化DH10Bac感受态,通过Tn7转座子将目的基因转座到Bacmid中,得到Bacmid-HBV pre-c-Fc穿梭载体,脂质体包被后转染Sf9昆虫细胞获得P1代病毒,重复转染Sf9获得高滴度病毒。收集细胞上清超滤后通过Protein G亲和层析柱纯化得到目的蛋白HBV pre-c-Fc。纯化的蛋白大腿内侧肌肉注射免疫BALB/c小鼠并检测血清中乙型肝炎病毒核心蛋白抗体产生量。结果:HBV pre-c-Fc在昆虫细胞中成功表达,纯化后蛋白纯度达90%以上,蛋白产量约为3.03mg/L,纯化蛋白能有效刺激BALB/c小鼠产生特异抗体。结论:成功地在杆状病毒表达系统中表达了具有免疫原性的HBV pre-c-Fc蛋白,为生产乙肝治疗性疫苗奠定了基础。