葡萄酒酿酒酵母嗜果糖特性的评价方法

[目的]酿酒酵母的嗜果糖性是葡萄酒酵母选育工作的一项重要内容.建立评价菌体发酵果糖能力的方法,是葡萄酒酿酒酵母嗜果糖性研究的基础.[方法]以3株不同果糖发酵能力的酵母菌为研究对象,考察菌体在模拟葡萄汁培养基条件下,发酵情况与单糖利用之间的关系;并通过数学方程拟合单糖动力发酵曲线,得到发酵持续时间、葡萄糖浓度拟为0时的果糖浓度、果糖与葡萄糖曲线面积的差值等参数.[结果]这些参数可以反应出菌体的发酵速率和嗜果糖性.其中后两个参数能显著将3个菌株的嗜果糖特性区分开.[结论]为高果糖利周优良葡萄酒酿酒酵母菌株的筛选和构建,提供了较为全面、客观和有效的评价方法.     

利用环形染色体构象捕获技术对Bci11b基因座位在细胞核内空间组织的研究

环形染色体构象捕获（4c）技术实现了在全基因组范围内捕获与4c靶位点发生相互作用的基因座位,因而通过4C相关技术可以进一步研究靶基因座位在细胞核内的空间组织形式。该文以ABclllb基因座位作为4C分析的靶位点,通过优化4C分析的反向巢式PCR扩增条件,实现4C分析PCR的高效扩增：并通过有限克隆筛选与普通测序分析相结合的方法,在全基因组范围内捕获到一些与BcHlb基因座位发生潜在相互作用的基因座位。这些基因座位与靶位点间的相互作用既有发生在相同染色体内的,也有发生在不同染色体之间的。这些基因座位间的相互作用表明了Bclllb基因座位在细胞核内复杂的空间组织形式。     

怀孕前后酒精摄入对雌鼠植入前胚胎DNA甲基化模式建立的影响

女性怀孕前后饮酒会对胎儿的发育及神经系统造成不利影响,称为“胎儿酒精综合征”（fetal alcohol spectrum disorders,FASD）。小鼠通常作为研究该病的动物模型。该实验采用体外培养技术及体内冲胚法研究雌鼠怀孕前后酒精摄入对各期植入前胚胎全基因组DNAT基化模式建立的影响。小鼠植入前胚胎体外培养实验发现,体外实验组I（怀孕前酒精处理组1,除8-cell外,其他各期胚胎的DNA甲基化水平明显低于体外对照组;体外实验组II（正常胚胎在含乙醇的培养基中培养）,各期植入前胚胎DNA甲基化水平均明显低于体外对照组。体内实验发现,体内实验组I（怀孕前酒精处理组）与体内的实验组II（怀孕后酒精处理组）,各期植入前胚胎DNA甲基化水平明显低于体内对照组。体内、外实验结果表明：受精前后酒精对各期植入前胚胎DNA甲基化模式的正确建立造成紊乱,该结果可为进一步揭示FSAD发病机制提供一定的实验基础。     

Assessment of the Resistance to Uranium (VI) Exposure by Arthrobacter sp. Isolated from Hanford Site Soil

Production of nuclear fuel has resulted in hazardous waste streams that have contaminated the soil and groundwater. Arthrobacter strains, G975, G968, and G954 were used in the prescreening tests to evaluate their tolerance to UO₂ ²⁺ and investigate bacteria-U(VI) interactions under oxidizing pH-neutral conditions. Experiments have shown G975 is the fastest growing and the most uranium tolerant strain that removed about 90% of uranium from growth media. Atomic Force Microscopy images exhibited an irregular surface structure, which perhaps provided a larger surface area for uranium precipitation. The data indicate that aerobic heterotrophic bacteria may offer a solution to sequestering uranium in oxic conditions, which prevail in the vadose zone.     

Role of Pigment Epithelium-Derived Factor (PEDF) in Arsenic-Induced Cell Apoptosis of Liver and Brain in a Rat Model

Although studies have shown that arsenic exposure can induce apoptosis in a variety of cells, the exact molecular mechanism of chronic arsenicosis remains unclear. Based on our previous study on human serum, the present study was to determine whether pigment epithelium-derived factor (PEDF) plays a role in the damage induced by chronic arsenic exposure in a rat model and to explore the possible signaling pathway involved. Thirty male Wistar rats were randomly divided into three groups and the arsenite doses administered were 0, 10, and 50 mg/L, respectively. The experiment lasted for 6 months. Our results showed that level of arsenic increased significantly in serum, liver, brain, and kidney in arsenic-exposed groups. It was indicated that PEDF protein was widely distributed in the cytoplasm of various types of cells in liver, brain, and kidney. PEDF protein level was only changed when the arsenite dose reached 50 mg/L in liver and brain, whereas it was not changed in the kidney. In order to investigate the possible mechanism of PEDF-exerted damages upon arsenite exposure, apoptosis in liver and brain was assessed. The proportion of apoptotic cells gradually increased with increasing arsenic administration. The ratio of Bax/Bcl-2 in the high arsenic group (50 mg/L) was significantly higher than that in the control group. Therefore, we thought PEDF played a role in cell apoptosis of liver and brain which induced by sodium arsenite exposure, and the results also demonstrated that Bax and Bcl-2 might be two key targets in the action of PEDF.     

Protective Effects of Mangiferin in Subchronic Developmental Lead-Exposed Rats

Lead is a ubiquitous environmental and industrial pollutant. Exposure to excessive amounts of lead is especially harmful to the central nervous systems of infants and young children, and oxidative stress has been reported as a major mechanism of lead-induced toxicity. To evaluate the ameliorative potential of antioxidant mangiferin (MGN) on lead-induced toxicity, Morris water maze test, determination of blood and bone lead concentration, determination of antioxidant status in plasma, as well as observation of ultrastructural changes in the hippocampus were carried out. In the present study, under a transmission electron microscope, ameliorated morphological damages in the hippocampus were observed in MGN-treated groups. Blood and bone lead concentration in MGN-treated groups lowered to some extent (p?<?0.05, p?<?0.01). The activities of antioxidant enzymes, glutathione (GSH) content, and the GSH/oxidized glutathione ratio in MGN-treated groups were increased, respectively. Further studies are needed to establish whether the observed differences were a direct cause of mangiferin on lead-induced toxicity or not. This study might provide clues for the treatment of lead-induced toxicity.     

Altered Plasma Concentrations of Trace Elements in Ulcerative Colitis Patients Before and After Surgery

Ileal pouch-anal anastomosis (IPAA) is a classical surgery for ulcerative colitis patients. However, knowledge on trace element alteration in patients who had undergone this surgery is limited. This study was conducted to assess trace element alteration in patients with ulcerative colitis before and after ileal pouch-anal anastomosis. Preoperative (40) and postoperative (35) ulcerative colitis patients were studied. The dietary assessment of trace element intake was undertaken by a semiquantitative food frequency questionnaire. Patients' trace element status of zinc, copper, manganese, selenium, calcium, iron, and vitamin D₃ was assessed by measuring their blood concentrations. We found that with the similar dietary intake, there was no statistical difference in the concentrations of plasma copper, iron, calcium, and vitamin D₃ in the two groups (P?>?0.05). Compared with preoperative patients, postoperative patients had higher concentrations of plasma zinc (14.51?±?4.75 μmol/l) and manganese (0.21?±?0.11 μmol/l) and lower concentrations of plasma selenium (0.86?±?0.58 μmol/l). Both preoperative and postoperative mean concentrations of plasma calcium and vitamin D₃ were below their reference range, respectively. We conclude that IPAA does not seem to alter patients' abnormal trace elements completely. It is important to monitor and supply some specified trace elements even in postoperative patients.     

Speciation, Distribution, and Bioavailability of Soil Selenium in the Tibetan Plateau Kashin–Beck Disease Area—A Case Study in Songpan County, Sichuan Province, China

To clarify the relationship between the soil selenium distribution and its bioavailability with the distribution of Kashin–Beck disease (KBD) endemic areas on the eastern edge of the Tibetan Plateau, samples of natural soil (0–20 cm), cultivated topsoil, and main crops of the region (highland barley) were collected at different altitudes according to topographical and geomorphological features in both KBD and non-KBD areas of Songpan County. These samples were used for determination and analysis of total selenium content in soil and highland barley and available selenium that can be absorbed and utilized by plants. The results showed that the average total selenium content of natural and cultivated topsoil in KBD areas was lower than that in non-KBD areas (natural soil, P?=?0.061; cultivated soil, P?=?0.002), which is in agreement with the geographical distributions of selenium in other KBD-affected areas. However, the total soil selenium content exhibits certain micro-spatial distribution features, namely, the total selenium content in some endemic areas was significantly higher than that of non-KBD areas. This result was contrary to the general distribution that total selenium content in a KBD-affected area is lower than that in a non-KBD area. We further studied the extraction rate and content of soil selenium in six different fractions. The results indicated that the content and extraction rate of available selenium in KBD-affected areas were significantly lower than those in non-KBD areas. There is a distinct positive correlation between plant-available selenium and highland barley selenium (r?=?0.875, P?=?0.001) and a distinct negative correlation with altitude (r?=??0.801, P?=?0.010). Therefore, in KBD endemic areas, the selenium content in crops decreases as the available selenium content in soil decreases and is closely related to the geographical environment features (such as altitude and precipitation). These results suggest that the soil available selenium and ecological features are important factors that restrict the dietary selenium flux for residents in KBD endemic areas of the Tibetan Plateau, providing a theoretical and experimental basis for implementing agricultural measures to regulate the ecological cycle of the selenium flux in the KBD endemic area.     

Selenoprotein P and Yunnan Endemic Sudden Cardiac Death—an Ecological Study

The aim of the present study was to explore the role of selenoprotein P (SePP) in the etiology of the endemic sudden cardiac death in Yunnan, China. The levels of SePP of 124 subjects and glutathione peroxidase (GPx) of 119 subjects were measured. The subjects were from the old and new endemic areas and non-endemic areas. The levels of SePP and GPx of the subjects of the old endemic area were significantly higher than those of the subjects of the new endemic area and the non-endemic areas, respectively. The Pearson’s correlation among SePP, GPx, and the number of the incident cases of the disease were statistically significant. These correlations show that there is an inverse relationship among the number of patients and the levels of SePP (r? = ?? 0.9800, P ?= ?0.0200) and GPx (r? = ?? 0.961, P ?= ?0.009). The results show that selenium deficiency might play an important role in the incidence of the disease.     

Altitudinal Distribution of Ammonia-Oxidizing Archaea and Bacteria in Alpine Grassland Soils Along the South-Facing Slope of Nyqentangula Mountains,Central Tibetan Plateau

Nitrogen is a major limiting nutrient for the net primary production of terrestrial ecosystems, especially on sentinel alpine ecosystem. Ammonia oxidation is the first and rate-limiting step on nitrification process and is thus crucial to nitrogen cycle. To decipher climatic influence on ammonia oxidizers, their communities were characterized by qPCR and clone sequencing by targeting amoA genes (encoding the alpha subunit of ammonia mono-oxygenase) in soils from 7 sites over an 800 m elevation transect (4400–5200 m a.s.l.), based on “space-to-time substitution” strategy, on a steppe-meadow ecosystem located on the central Tibetan Plateau (TP). Archaeal amoA abundance outnumbered bacterial amoA abundance at lower altitude (<4800 m a.s.l.), but bacterial amoA abundance was greater in surface soils at higher altitude (≥4800 m a.s.l.). Archaeal amoA abundance decreased with altitude in surface soil, while its abundance stayed relatively stable and was mostly greater than bacterial amoA abundance in subsurface soils. Conversely, bacterial amoA abundance gradually increased with altitude at all three soil depths. Statistical analysis indicated that altitude-dependent factors, in particular pH and precipitation, had a profound effect on the abundance and community of ammonia-oxidizing bacteria, but only on the community composition of ammonia-oxidizing archaea along the altitudinal gradient. These findings imply that the shifts in the relative abundance and/or community structure of ammonia-oxidizing bacteria and archaea may result from the precipitation variation along the altitudinal gradient. Thus, we speculate that altitude-related factors (mainly precipitation variation combing changed pH), would play a vital role in affecting nitrification process on this alpine grassland ecosystem located at semi-arid area on TP.