A robust approach to estimate relative phytoplankton cell abundances from metagenomes

Phytoplankton account for >45% of global primary production, and have an enormous impact on aquatic food webs and on the entire Earth System. Their members are found among prokaryotes (cyanobacteria) and multiple eukaryotic lineages containing chloroplasts. Genetic surveys of phytoplankton communities generally consist of PCR amplification of bacterial (16S), nuclear (18S) and/or chloroplastic (16S) rRNA marker genes from DNA extracted from environmental samples. However, our appreciation of phytoplankton abundance or biomass is limited by PCR-amplification biases, rRNA gene copy number variations across taxa, and the fact that rRNA genes do not provide insights into metabolic traits such as photosynthesis. Here, we targeted the photosynthetic gene psbO from metagenomes to circumvent these limitations: the method is PCR-free, and the gene is universally and exclusively present in photosynthetic prokaryotes and eukaryotes, mainly in one copy per genome. We applied and validated this new strategy with the size-fractionated marine samples collected by Tara Oceans, and showed improved correlations with flow cytometry and microscopy than when based on rRNA genes. Furthermore, we revealed unexpected features of the ecology of these ecosystems, such as the high abundance of picocyanobacterial aggregates and symbionts in the ocean, and the decrease in relative abundance of phototrophs towards the larger size classes of marine dinoflagellates. To facilitate the incorporation of psbO in molecular-based surveys, we compiled a curated database of >18,000 unique sequences. Overall, psbO appears to be a promising new gene marker for molecular-based evaluations of entire phytoplankton communities.     

塔拉凉嗓含片安全性评价研究

进行了塔拉凉嗓含片的毒理试验、感官和理化指标检测,以检测其安全性。检验的结果表明:在本试验条件下,在急性经口毒性试验中,受试物塔拉凉嗓含片对受试动物小白鼠急性经口毒性试验LD50大于10000 mg/kg.bw,属实际无毒级;骨髓细胞微核试验,塔拉凉嗓含片对小白鼠骨髓细胞无致微核作用;感官和理化指标检测,结果全部在国家相关产品所允许的指标范围之内。     

Echinophyllia tarae sp. n. (Cnidaria,Anthozoa, Scleractinia), a new reef coral species from the?Gambier Islands,French Polynesia

A new shallow water scleractinian coral species, Echinophyllia tarae sp. n., is described from the Gambier Islands, French Polynesia. It is characterized by an encrusting corallum, a few large and highly variable corallites with protruding walls, and distinctive costosepta. This coral was observed in muddy environments where several colonies showed partial mortality and re-growth. The new species has morphological affinities with both Echinophyllia echinata and with Echinomorpha nishihirai, from which it can be distinguished on the basis of the diameter and the protrusion of the largest corallite, the thickness of the septa, and the development of the size of the crown of paliform lobes.     

塔拉豆荚壳中单宁的提取-微波辅助萃取法

利用微波辅助萃取技术对塔拉单宁进行提取,通过不同的起始温度、加蒸馏水量、提取次数、功率大小等实验并用1%的FeCl3溶液检测提取效果,确定较佳的提取温度、次数、加蒸馏水量和微波辅助萃取仪的功率等因素。结果表明,微波提取塔拉单宁的最佳提取条件为:每次提取加水150~200 mL,微波功率400 w,60℃提取20 min,反复提取4次;再升温至70℃提取20 min 2次,即可提取完全。原料中的单宁含量微波浸提比水浴锅浸提稍高。因此认为用此提取方法可替代水浴浸提法。     

塔拉种子多糖脱蛋白的正交优化及其抗氧化性研究

以塔拉（Caesalpinia spinosa）种子为原料,研究了塔拉种子多糖的脱蛋白工艺及塔拉多糖的抗氧化性质。以多糖损失率和蛋白脱除率为评价指标,比较Sevage法、三氯乙酸法和木瓜蛋白酶法对塔拉多糖的脱蛋白效果。利用正交优化组合实验设计原理,采用四因素三水平的正交分析法,对木瓜蛋白酶法脱蛋白进行正交优化。结果表明：塔拉多糖最佳脱蛋白工艺条件为酶添加量0.15mL、酶解时间90min、酶解温度60℃、酶解pH=6,蛋白脱除率95.19%,多糖保留率75.02%。通过对塔拉多糖抗氧化性的研究,发现塔拉多糖总抗氧化性较好,对DPPH自由基有较强的清除作用。     

Characterization of galactomannans isolated from legume endosperms of Caesalpinioideae and Faboideae subfamilies by multidetection aqueous SEC

Galactomannans isolated from legume seed endosperms, including those of commercial interest, have been characterized by multidetection aqueous SEC. Galactomannans derived from seeds of the Faboideae subfamily had substantially higher M_w than those from Caesalpinioideae seeds (M_w,Fab = 2.4–3.1 × 10⁶ g/mol, M_w,Caes. = 0.86–2.1 × 10⁶ g/mol) and within the latter botanical subfamily, an apparent correlation between M_w and the degree of galactose substitution DG was found. The molar mass distributions were unimodal and differed primarily by a scale factor, with distributional widths narrower than a true Flory ‘most-probable distribution’; good fits to Schulz–Zimm model were obtained. Across subfamilies no differences were found in the exponents of [η]–M and R_v–M relationships (0.61 ± 0.02, 0.54 ± 0.01, respectively), the Flory chain stiffness ratio (C_∞ = 20 ± 1 (BSF analysis)), or the persistence length (L_p = 5.5 ± 0.2 nm) obtained from SEC fraction data. However, it was found that prefactors in the [η]–M and R_v–M relationships as well as the unperturbed parameter K_Θ decrease in proportion to DG and therefore chain density. Generalized relationships incorporating galactose-dependent prefactors were therefore developed to model SEC fraction data of native galactomannans ([η]_GM = (1800 ± 200) × M_o^−1.61 × M^0.61±0.02, R_v,GM = 0.63 ± 0.05 × M_o^−0.54 × M^0.54±0.01) as well as lower-M fractions obtained by ultrasonication ([η]_GM = (730 ± 100) × M_o^−1.71 × M_w^0.71±0.02, R_v,GM = 0.49 ± 0.05 × M_o^−0.57 × M_w^0.57±0.01, M ≈ 1 × 10⁵-native). As a consequence of this dependence and the observed patterns in molar mass variation, [η] varies within a narrow range for galactomannans as a whole despite substantial M_w differences.     

烘炒法分离提取半乳甘露聚糖型种子胶

种子多糖胶分离提取工艺试验表明,根据种子胚乳坚硬的物理性能,用机械分离方法分离种子胚乳,其多糖胶抽提率大于80％。烘炒法适用于种皮厚而硬一类种子胚乳的分离,正交试验表明烘炒温度对种子多糖胶抽提率和粘度指标影响最大;皂荚胚乳的最优化分离条件是种子在80℃下预热60min,然后在160℃烘炒机中烘炒4min,再进入开片、选片和筛选工序;野皂荚胚乳的分离条件是种子80℃时预热30min,130℃下烘炒3min。     

塔拉豆中塔拉胶含量的分析测定方法研究

介绍了塔拉豆的研究现状,并对塔拉豆中塔拉胶含量的分析测定方法进行了研究。结果显示:塔拉胶的分离条件为:烘炒温度为150℃,时间7 min,每小组为4颗成熟饱满的塔拉豆。烘炒后破碎,塔拉胶和其余两部分的分离效果好,塔拉胶的经济性状也完整。每个分析样品所需塔拉豆的数量:5小组(即20颗塔拉豆)为一组实验结果,三组平行实验结果经过方差分析达到实验要求。     

塔拉豆及其化学成分的研究

本文分析测定了云南元江产塔拉种子的物理组成和塔拉胶的总糖、聚糖、粗纤维、粗蛋白等化学成分,对塔拉胶性能也做了测定,并对塔拉多糖的化学结构进行了初步鉴定,为塔拉种子的开发利用提供了科学依据。