Protistan microbial observatory in the Cariaco Basin,Caribbean. I. Pyrosequencing vs Sanger insights into species richness

Microbial diversity and distribution are topics of intensive research. In two companion papers in this issue, we describe the results of the Cariaco Microbial Observatory (Caribbean Sea, Venezuela). The Basin contains the largest body of marine anoxic water, and presents an opportunity to study protistan communities across biogeochemical gradients. In the first paper, we survey 18S ribosomal RNA (rRNA) gene sequence diversity using both Sanger- and pyrosequencing-based approaches, employing multiple PCR primers, and state-of-the-art statistical analyses to estimate microbial richness missed by the survey. Sampling the Basin at three stations, in two seasons, and at four depths with distinct biogeochemical regimes, we obtained the largest, and arguably the least biased collection of over 6000 nearly full-length protistan rRNA gene sequences from a given oceanographic regime to date, and over 80 000 pyrosequencing tags. These represent all major and many minor protistan taxa, at frequencies globally similar between the two sequence collections. This large data set provided, via the recently developed parametric modeling, the first statistically sound prediction of the total size of protistan richness in a large and varied environment, such as the Cariaco Basin: over 36 000 species, defined as almost full-length 18S rRNA gene sequence clusters sharing over 99% sequence homology. This richness is a small fraction of the grand total of known protists (over 100 000–500 000 species), suggesting a degree of protistan endemism.     

Morphological and Molecular Identification of Spirometra Tapeworms (Cestoda: Diphyllobothriidae) from Carnivorous Mammals in the Serengeti and Selous Ecosystems of Tanzania

Spirometra tapeworms (Cestoda: Diphyllobothriidae) collected from carnivorous mammals in Tanzania were identified by the DNA sequence analysis of the mitochondrial cytochrome c oxidase subunit 1 (cox1) and internal transcribed spacer 1 (ITS1), and by morphological characteristics. A total of 15 adult worms were collected from stool samples and carcasses of Panthera leo, Panthera pardus, and Crocuta crocuta in the Serengeti and Selous ecosystems of Tanzania. Three Spirometra species: S. theileri, S. ranarum and S. erinaceieuropaei were identified based on morphological features. Partial cox1 sequences (400 bp) of 10 specimens were revealed. Eight specimens showed 99.5% similarity with Spirometra theileri ({"type":"entrez-nucleotide","attrs":{"text":"MK955901","term_id":"1796114604","term_text":"MK955901"}}MK955901), 1 specimen showed 99.5% similarity with the Korean S. erinaceieuropaei and 1 specimen had 99.5% similarity with Myanmar S. ranarum. Sequence homology estimates for the ITS1 region of S. theileri were 89.8% with S. erinaceieuropaei, 82.5% with S. decipiens, and 78.3% with S. ranarum; and 94.4% homology was observed between S. decipiens and S. ranarum. Phylogenetic analyses were performed with 4 species of Spirometra and 2 species of Dibothriocephalus (=Diphyllobothrium). By both ML and BI methods, cox1 and ITS1 gave well supported, congruent trees topology of S. erinaceieuropaei and S. theileri with S. decipiens and S. ranarum forming a clade. The Dibothriocephalus species were sisters of each other and collectively forming successive outgroups. Our findings confirmed that 3 Spirometra species (S. theileri, S. ranarum, and S. erinaceieuropaei) are distributed in the Serengeti and Selous ecosystems of Tanzania.     

Induction of interdigitating reticulum cell-like differentiation in human monocytic leukemia cells by conditioned medium from IL-2-stimulated helper T-cells

Monocytic leukemia (MoL) cells were obtained from the peripheral blood of a patient in whom the leukemic cells infiltrating various lymphoreticular organs exhibited features intermediate between interdigitating reticulum cells (IDC) and ordinary phagocytic macrophages, whereas the leukemic cells in the peripheral blood were essentially monocytic and lacked such features. Peripheral blood CD4+ T-cells were established as an interleukin-2-dependent T-cell line. When the MoL cells were exposed for a few days to conditioned medium from the T-cell line, they extended several dendritic cytoplasmic projections and became intensely positive for HLA-DR antigen, cytoplasmic S-100β protein, and CD1 antigen. Functionally, the conditioned medium significantly down-regulated Fc-mediated and Fc-independent phagocytic activities, and the levels of lysosomal enzymes such as lysozyme and nonspecific esterase in the MoL cells. Moreover, the conditioned medium significantly up-regulated the accessory cell function of the MoL cells as measured by the primary allogenic mixed leukocyte reaction (MLR). Furthermore, the conditioned medium significantly down-regulated the expression of CD14 antigen. Biochemical analysis indicated that the factor responsible for these changes is a protein which is distinct from known human cytokines and whose molecular weight is approximately 31 kDa. These findings suggest that IDC are closely related the monocytic lineage and that helper T-cells play an important role in constructing the microenvironment of T-lymphoid tissues which is necessary for the differentiation and maturation of IDC.     

用TOPSIS方法评价黄土丘陵区草场质量的研究

一、自然概况黄土高原位于我国西北部,西起青海日月山,东抵山西太行山,北至晋陕长城,南达甘陕秦岭,构成一个独具特色的、比较完整的自然区域,其地理范围大致是北纬34°—41°,东经103°—113°之间。高原到处有起伏的黄     

狗的无氧阈与骨骼肌某些特征在锻炼、脱锻炼动态变化中的关系

本实验在体力锻炼与脱锻炼过程中观察了五条成年雄性杂种狗的无氧阈(AT)、骨骼肌毛细血管密度(cap/mm~2)、毛细血管数与肌纤维数之比(C:F)、肌纤维组成——慢肌纤维百分比(％ST)以及毛细血管弥散距离(弥散距离)的变化。结果表明:锻炼前AT与cap/mm~2、C:F,％ST及弥散距离均分别有显著相关。锻炼后第五周,AT、cap/mm~2、C:F和％ST分别增加了40.9％、12.2％、22.9％和2.4％,弥散距离降低6.3％,其中只有AT的增加有显著意义,锻炼十周后,AT增加68.2％(P<0.001)、cap/mm~2增加37.8％(P<0.05)、C:F增加78.1％(P<0.001),弥散距离降低17.0％(P<0.01)而％ST无显著变化。停止锻炼后第五周,AT等各指标都有降低的趋势,但无显著意义,停止锻炼后第12周,AT、cap/mm~2,C:F,％ST分别降低了18.9％、10.9％、10.5％、2.9％,弥散距离增加5.1％,其中除AT的降低有显著意义外,其余指标的变化均无显著意义。与锻炼前相比,这些指标的变化。除％ST外,仍有显著变化。在锻炼与脱锻炼的过程中,AT与cap/mm~2、C:F、弥散距离在各期或整个过程中均呈显著相关,但与％ST相关不显著。实验结果提示,骨骼肌的毛细血管供应状况是决定无氧阈的重要因素之一。     

Recycling of membrane proteins during endo- and exocytosis in amoebae

The fate of a membrane protein of the amoeba plasmalemma was studied by means of 125I iodination by lactoperoxidase, gel electrophoresis, radioautography and gamma counting. There was only one iodinatable polypeptide group with a molecular weight (MW) of 175 000 on the external surface of the plasmalemma. Two hours or more after induced phagocytosis, isolated phagolysosomal membranes contained two other smaller polypeptides with MWs of 70 000 and 35 000, respectively, suggesting that the 175 000 polypeptide was broken down to these smaller components during endocytosis. After 22 h of induced phagocytosis, isolated plasmalemma contained a 35 000 polypeptide group in addition to the 175 000 polypeptide species. The results suggested that some of the iodinatable membrane proteins were altered and recycled during endo- and exocytosis in amoebae, while others were recycled intact.