In Vitro Susceptibility of <Emphasis Type="Italic">C. albicans</Emphasis> and <Emphasis Type="Italic">C. neoformens</Emphasis> to Potential Metabolites from <Emphasis Type="Italic">Streptomycetes</Emphasis>

Forty two Streptomycetes isolates from soils of Kodachadri region in Western ghats were recovered by soil dilution technique. Cross streak method was followed for primary screening of antifungal activity. Positive isolates were subjected to secondary screening by cold extraction of fermentation broth in butanol solvent. Six isolates exhibited broad spectrum antifungal activity against all the tested yeast pathogens like Candida albicans, Candida lipolytica, Cryptococcus neoformens and Saccharomyces cerevisiae. One isolate showed excellent antifungal activity against all test organisms with maximum zone of inhibition 60 mm each incase of C. neoformens and C. albicans. Partial characterization of antifungal metabolite by TLC resulted in a purple spot with an R_f value 0.50. The UV absorption spectra at 218 nm indicated possible chemical nature of the active metabolite as polyene group and purity was assessed by analytical HPLC.     

Detrimental effect on availability of buserelin acetate administered in seminal doses in rabbits

The study evaluated a seminal effect on the ability to induce ovulation of a synthetic GnRH analogue, buserelin acetate, administered by vaginal mucosa in rabbit does. In a first experiment, 751 receptive nulliparous and multiparous non-lactating does were randomly assigned to groups of different seminal doses (6, 12, 24, 50, and 100 million total sperm in 0.5 mL). All seminal doses contained 5μg of buserelin acetate to induce ovulation by vaginal mucosa absorption. Two hundred and six does from 751 were laparoscopized at 12^th days of gestation to evaluate ovulation induction, ovulation rate and implanted embryos, while pregnancy rate and total and live born were noted in all females. Results showed that the pregnancy rate was significantly affected by the seminal dose used (0.82 vs 0.72, 0.50, and 0.45, for 6, 24, 50, and 100 million of spermatozoa, respectively). Data from laparoscopized does showed significant differences between the group of 6 and 50 million sperm dose in the ovulation induction and consequently in the pregnancy rate (0.79 vs 0.52, 0.79 vs 0.48, respectively). Does from all groups had similar implanted embryos and litter sizes irrespective of seminal dose used. In a second experiment, inseminations were done without spermatozoa, 0.5 mL of two dilutions of seminal plasma (1/4 and 1/20) with 5μg of buserelin acetate were introduced into vagina from 71 receptive females and its results were compared to a control group (35 does) induced to ovulate with 1μg of buserelin acetate administered intramuscularly. Only 40% of females from 1/4 plasma dilution group became to ovulate. Consequently, the dilution rate of seminal plasma may reduce the availability rate of the GnRH analogue and the concentration needed to provoke the ovulation induction.     

Application of fast chlorophyll a fluorescence kinetics to probe action target of 3-acetyl-5-isopropyltetramic acid

3-Acetyl-5-isopropyltetramic acid (3-AIPTA), an analogue of the phytotoxin tenuazonic acid, is a tetramic acid derivate. It is demonstrated here that 3-AIPTA is a multi-target inhibitor of root and shoot growth as well as photosynthesis. Based on fast chlorophyll fluorescence kinetics, 3-AIPTA blocks electron transport beyond Q_A on the acceptor side of PSII by competing with Q_B for the Q_B-binding site, but does not affect the donor side and the light harvesting function of the PSII antenna. Additionally, higher 3-AIPTA concentration also inhibits the reduction of end acceptors of PSI. Evidences from JIP-test and competitive replacement with [¹⁴C]atrazine showed that 3-AIPTA, like tenuazonic acid, does not share the same binding environment with the atrazine-like PSII inhibitors although they possess the common action target of the Q_B-site. It is deduced that tetramic acid families of natural products, where 3-AIPTA and tenuazonic acid belong to, is a novel inhibitor type of the photosynthetic electron transport chain.     

Characterization of main sulfur source of wood-degrading basidiomycetes by S K-edge X-ray absorption near edge spectroscopy (XANES)

The main wood degraders in aerobic terrestrial ecosystems belong to the white- and brown-rot fungi, where their biomass can be created on wood decay only. However, total sulfur (S) concentration in wood is very low and only little is known about the different sulfur compounds in wood today. Sulfur-starved brown-rot fungi Gloeophyllum trabeum and Oligoporus placenta were incubated on sterilized pine wood blocks whereas Lentinus cyathiformis and the white-rot fungi Trametes versicolor were incubated on sterilized beech wood blocks. After 19 weeks of incubation, the S oxidation status was analyzed in wood, in degraded wood, and in biomass of wood-degrading fungi by synchrotron based S K-edge XANES, and total S and sulfate were quantified. Total sulfur and sulfate content in pine wood blocks were approximately 50 and 1 ??g g⁻¹, respectively, while in beech wood approximately 100 and 20 ??g g⁻¹ were found, respectively. Sulfur in beech was dominated by sulfate-esters. In contrast, pine wood also contained larger amounts of reduced S. Three out of four selected fungi caused a reduction of the S oxidation state in wood from oxidized S (sulfate-ester, sulfate) to intermediate S (sulfonate, sulfoxide) or reduced S (thiols, e.g., proteins, peptides, enzyme cofactors). Only O. placenta shifted thiol to sulfonate. Growth experiments of these fungi on selective minimal media showed that in particular cysteine (thiol), sulfonates, and sulfate enhanced total mycelium growth. Consequently, wood-degrading fungi were able to utilize a large variety of different wood S sources for growth but preferentially transformed in vivo sulfate-esters and thiol into biomass structures.     

水分亏缺下紫花苜蓿和高粱根系水力学导度 与水分利用效率的关系

利用聚乙二醇(PEG-6000)模拟水分亏缺条件(胁迫水势-0.2MPa,胁迫48h),研究了变水条件下紫花苜蓿(品种:阿尔冈金和陇东)和高粱(品种:抗四)根系水力学导度(Lp_r)、根系活力、根叶相对含水量、水分利用效率等参数的动态变化,以期进一步明确植物水分吸收及散失过程调控的生理生态学基础。结果表明:水分亏缺限制了紫花苜蓿和高粱根系吸水,表现在Lp_r的下降和根系活力的降低;继而调控了其地上部反应,引起气孔导度、光合速率、叶片相对含水量和蒸腾速率等的下降,但限制性的提高了其水分利用效率,尤其在胁迫初期。恢复到正常供水条件后,Lp_r、根系活性、气孔导度等水分利用参数逐渐部分或完全恢复到了胁迫前水平,但恢复程度存在种间和品种间差异,并且根系吸水能力的恢复对于是植株地上部生长状态的恢复至关重要,尤其是水分恢复初期。紫花苜蓿根系中检测到水通道蛋白(AQPs)的存在,水分亏缺对紫花苜蓿Lp_r的影响认为主要是通过影响AQPs的活性实现的。比较紫花苜蓿和高粱水分吸收与利用状况在变水条件下的动态变化,认为紫花苜蓿幼苗对干旱逆境的适应能力相对弱于高粱,品种间陇东适应能力更强。     

水杨酸对NaCl胁迫下菊芋幼苗光合作用及离子吸收的影响

为探明水杨酸(SA)对NaCl胁迫下菊芋耐盐生理的调控作用,研究了100μmol·L-1水杨酸对不同浓度NaCl胁迫下菊芋幼苗光合响应特征及离子吸收运输的影响.结果表明:施用水杨酸不仅能够有效缓解NaCl胁迫对菊芋光合作用的抑制,促进NaCl胁迫下菊芋幼苗各种光合色素含量、净光合速率、蒸腾速率、气孔导度和水分利用效率的增加,降低细胞间隙CO2浓度,同时也能明显降低NaCl胁迫下菊芋体内Na+的积累,促进菊芋幼苗对K+和Ca2+的吸收和向上运输,其中在100 mmol·L-1 NaCl处理下施用水杨酸处理的菊芋叶片中K+和Ca2+含量分别比未施用水杨酸处理增加了12.9％和14.7％,而Na+含量则降低了30.6％.由此证明,一定浓度外源水杨酸的施用有利于促进NaCl胁迫下菊芋幼苗光合功能的改善,以及有效维持菊芋幼苗体内矿质营养元素含量平衡,从而增强菊芋对NaCl胁迫的抗性,提高NaCl胁迫下的生产力.     

黄喉鹀的羽色与雄鸟质量相关性分析

在国内首次利用光纤光谱仪对鸟类的羽色进行量化和分析.对黄喉鹀Emberiza elegans雌、雄鸟羽色的差异以及雄鸟羽色与雄鸟质量的相关性分析结果表明,黄喉鹀雌、雄鸟在人眼看来相同的黄色羽和白色羽部分,在紫外光色度上却存在显著差异,雄鸟紫外光色度高于雌鸟;雄鸟的质量与脸部黑色羽的亮度、可见光色度和色调呈显著正相关,雌...     

Role of specific activators of intestinal amino acid transport in Bombyx mori larval growth and nutrition.

Nutrient absorption and its modulation are critical for animal growth. In this paper, we demonstrate that leucine methyl ester (Leu-OMe) can greatly increase the activity of the transport system responsible for the absorption of most essential amino acids in the larval midgut of the silkworm Bombyx mori. We investigated leucine uptake activation by Leu-OMe in brush border membrane vesicles and in the apical membrane of epithelial cells in the midgut incubated in vitro. Moreover, the addition of this strong activator of amino acid absorption to diet significantly affected larval growth. Silkworms fed on artificial diet supplemented with Leu-OMe reached maximum body weight 12-18 h before control larvae, and produced cocoon shells up to 20% heavier than those of controls. The activation of amino acid absorption plays an essential role in larval development so that larval growth and cocoon production similar to controls reared on an artificial diet with 25% of dry mulberry leaf powder were observed in silkworms fed on an artificial diet with only 5% of mulberry powder. Arch.     

Dynamics of absorption in gut and reabsorption in kidney of yellow fluorescent protein in rat postnatal ontogenesis

In experiments on rats aged 5, 12, and 25 days and on adult rats, absorption of yellow fluorescent protein (YFP) in small intestine was shown, with its subsequent entry to kidney with blood flow and accumulation in cells of the nephron proximal segment. With age, intensity of the YEP absorption in the gut decreased; the YEP accumulation in kidney was somewhat more active in the rat pups of younger age groups than in adult animals. No accumulation of YEP was revealed in liver. The obtained results indicate an intensive absorption in the rat pup small intestine in early postnatal ontogenesis and an important role of kidney in protein metabolism and proteolysis of alien proteins.     

Increased peripheral lipid clearance in an animal model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is the most common adult motor neuron disease, causing motor neuron degeneration, muscle atrophy, paralysis, and death. Despite this degenerative process, a stable hypermetabolic state has been observed in a large subset of patients. Mice expressing a mutant form of Cu/Zn-superoxide dismutase (mSOD1 mice) constitute an animal model of ALS that, like patients, exhibits unexpectedly increased energy expenditure. Counterbalancing for this increase with a high-fat diet extends lifespan and prevents motor neuron loss. Here, we investigated whether lipid metabolism is defective in this animal model. Hepatic lipid metabolism was roughly normal, whereas gastrointestinal absorption of lipids as well as peripheral clearance of triglyceride-rich lipoproteins were markedly increased, leading to decreased postprandial lipidemia. This defect was corrected by the high-fat regimen that typically induces neuroprotection in these animals. Together, our findings show that energy metabolism in mSOD1 mice shifts toward an increase in the peripheral use of lipids. This metabolic shift probably accounts for the protective effect of dietary lipids in this model.