Screening of genes related to ovary development in Chinese shrimp Fenneropenaeus chinensis by suppression subtractive hybridization

The ovary of triploid shrimp Fenneropenaeus chinensis was apparently impaired compared to that of the diploid shrimp at the same age. Therefore triploid shrimp ovary is possible to be taken as a model to understand the mechanism of ovary development of shrimp compared to that of the ovary of diploid shrimp at the same age. In the present study, a suppression subtractive hybridization (SSH) technique was applied to identify differentially expressed genes in the ovary between diploid and triploid shrimp. For the forward library (RNA from the ovary of triploid shrimp as the tester), 54 genes were identified. For the reverse library (RNA from the ovary of diploid shrimp as the tester), 16 genes were identified. The identified genes encoded proteins with multiple functions, including extracellular matrix components, cytoskeleton, cell growth and death, metabolism, genetic information processing, signal transduction/transport or immunity related proteins. Eleven differentially expressed genes were selected to be confirmed in the ovaries of triploid and diploid shrimp by semi-quantitative RT-PCR. Genes encoding spermatogonial stem-cell renewal factor, cytochrome c oxidase subunits I and II, clottable protein, antimicrobial peptide and transposase showed up-regulated expressions in the ovary of triploid shrimp. Genes encoding tubulin, cellular apoptosis susceptibility protein, farnesoic acid O-methyltransferase, thrombospondin and heat shock protein 90 genes showed higher expressions in the ovary of diploid shrimp. The differential expressions of the above genes are suggested to be related to the ovary development of shrimp. It will provide a new clue to uncover the molecular mechanisms underlying the ovarian development in penaeid shrimp. (C) 2010 Elsevier Inc. All rights reserved.

Difterentially expressed genes of Tetrahymena thermophila in response to tributyltin (TBT) identified by suppression subtractive hybridization and real time quantitative PCR

Tributyltin (TBT) is widely used as antifouling paints, agriculture biocides, and plastic stabilizers around the world, resulting in great pollution problem in aquatic environments. However, it has been short of the biomonitor to detect TBT in freshwater. We constructed the suppression subtractive hybridization library of Tetrahymena thermophila exposed to TBT, and screened out 101 Expressed Sequence Tags whose expressions were significantly up- or down-regulated with TBT treatment. From this, a series of genes related to the TBT toxicity were discovered, such as glutathione-S-transferase gene (down-regulated), plasma membrane Ca2+ ATPase isoforms 3 gene (up-regulated) and NgoA (up-regulated). Furthermore, their expressions under different concentrations of TBT treatment (0.5-40 ppb) were detected by real time fluorescent quantitative PCR. The differentially expressed genes of T thermophila in response to TBT were identified, which provide the basic to make Tetrahymena as a sensitive, rapid and convenient TBT biomonitor in freshwater based on rDNA inducible expression system. (c) 2006 Elsevier B.V. All rights reserved.

Identification of differentially expressed genes in Tetrahmena thermophila in response to dichlorodiphenyltrichloroethane (DDT) by suppression subtractive hybridization

The insecticide dichlorodiphenyltrichloroethane (DDT) is persistent in the environment, and continues to cause health problems. Tetrahymena has potential as a model organism for assaying low levels of DDT and for analysing the mechanisms of its toxicity. We constructed the suppression subtractive hybridization library of T thermophila exposed to DDT, and screened out 90 Expressed Sequence Tags whose expressions were significantly up- or downregulated with DDT treatment. From this, a series of important genes related to the DDT metabolism and detoxification were discovered, such as P450 gene, glutathione S-transferase gene and sterol carrier protein 2 gene. Furthermore, their expressions under different concentrations of DDT treatment were detected by real-time fluorescent quantitative PCR. The results show that Tetrahymena is a relevant and useful model organism for detecting DDT in the environment and for discovering biomarkers that can be used to develop specific bio-reporters at the molecular and genomic levels.

Donut-Shaped Fingerprint In Homologous Polypeptide Relationships-A Topological Feature Related To Pathogenic Structural Changes In Conformational Disease

Features of homologous relationship of proteins can provide us a general picture of protein universe, assist protein design and analysis, and further our comprehension of the evolution of organisms. Here we carried Out a Study of the evolution Of protein molecules by investigating homologous relationships among residue segments. The motive was to identify detailed topological features of homologous relationships for short residue segments in the whole protein universe. Based on the data of a large number of non-redundant Proteins, the universe of non-membrane polypeptide was analyzed by considering both residue mutations and structural conservation. By connecting homologous segments with edges, we obtained a homologous relationship network of the whole universe of short residue segments, which we named the graph of polypeptide relationships (GPR). Since the network is extremely complicated for topological transitions, to obtain an in-depth understanding, only subgraphs composed of vital nodes of the GPR were analyzed. Such analysis of vital subgraphs of the GPR revealed a donut-shaped fingerprint. Utilization of this topological feature revealed the switch sites (where the beginning of exposure Of previously hidden "hot spots" of fibril-forming happens, in consequence a further opportunity for protein aggregation is Provided; 188-202) of the conformational conversion of the normal alpha-helix-rich prion protein PrPC to the beta-sheet-rich PrPSc that is thought to be responsible for a group of fatal neurodegenerative diseases, transmissible spongiform encephalopathies. Efforts in analyzing other proteins related to various conformational diseases are also introduced. (C) 2009 Elsevier Ltd. All rights reserved.

Delta EEG Activity in Left Orbitofrontal Cortex in Rats Related to Food Reward and Craving

眶额叶皮质与中脑边缘多巴胺奖赏系统有着复杂的相互纤维联系.先前的研究探讨了药物成瘾过程中眶额叶皮质的脑电活动.在本实验中,将探讨食物奖赏和渴求过程中该皮质的脑电活动.实验采用了两个环境:对照环境和食物刺激相关的环境.首先,训练大鼠在食物刺激相关的环境中吃巧克力花生豆,而后在该环境中设置两种不同的刺激方式:能看到和闻到但不能吃到(渴求实验),或者仍旧可以吃到巧克力花生豆(奖赏实验):同时进行左侧眶额叶皮质的脑电记录.结果发现,在食物刺激相关的环境中大鼠Delta频段(2-4Hz)的脑电活动与食物刺激显著相关,此外,与在对照环境中相比,其相对功率在食物渴求时下降而在食物奖赏时升高.本实验表明,食物相关的奖励可以改变大鼠眶额叶皮质的脑电活动,而且,Delta频段的脑电活动能够作为监测该奖励的一个指标.

Developmental toxicity and alteration of gene expression in zebrafish embryos exposed to PFOS

Perfluorooetanesulfonate (PFOS) is a persistent organic pollutant, the potential toxicity of which is causing great concern. In the present study, we employed zebrafish embryos to investigate the developmental toxicity of this compound. Four-hour post-fertilization (hpf) zebrafish embryos were exposed to 0.1, 0.5, 1, 3 and 5 mg/L PFOS. Hatching was delayed and hatching rates as well as larval survivorship, were significantly reduced after the embryos were exposed to 1, 3 and 5 mg/L PFOS until 132 hpf. The fry displayed gross developmental malformations, including epiboly deformities, hypopigmentation, yolk sac edema, tail and heart malformations and spinal curvature upon exposure to PFOS concentrations of I mg/L or greater. Growth (body length) was significantly reduced in the 3 and 5 mg/L PFOS-treated groups. To test whether developmental malformation was mediated via apoptosis, flow cytometry analysis of DNA content, acridine orange staining and TUNEL assay was used. These techniques indicated that more apoptotic cells were present in the PFOS-treated embryos than in the control embryos. Certain genes related to cell apoptosis, p53 and Bax, were both significantly up-regulated upon exposure to all the concentrations tested. In addition, we investigated the effects of PFOS on marker genes related to early thyroid development (hhex and pax8) and genes regulating the balance of androgens and estrogens (cyp19a and cyp19b). For thyroid development, the expression of hhex was significantly up-regulated at all concentrations tested, whereas pax8 expression was significantly up-regulated only upon exposure to lower concentrations of PFOS (0.1, 0.5, 1 mg/L). The expression of cyp19a and of cyp19b was significantly down-regulated at all exposure concentrations. The overall results indicated that zebrafish embryos constitute a reliable model for testing the developmental toxicity of PFOS, and the gene expression patterns in the embryos were able to reveal some potential mechanisms of developmental toxicity. (C) 2008 Elsevier Inc. All rights reserved.

Crustacean zooplankton distribution patterns and their biomass as related to trophic indicators of 29 shallow subtropical lakes

A comparative limnological study was carried out to present a snapshot of crustacean zooplankton communities and their relations to environmental factors to test whether there is a consistent relationship between crustacean biomass and trophic indicators among lake groups with similar trophic conditions. The study lakes showed a wide range of trophic status, with total phosphorus (TP) ranging from 0.008 to 1.448mgL(-1), and chlorophyll a from 0.7 to 146.1 mu g L-1, respectively. About 38 species of Crustacea were found, of which Cladocera were represented by 25 taxa (20 genera), and Copepoda by 13 taxa (I I genera). The most common and dominant species were Bosmina coregoni, Moina micrura, Diaphanosoma brachyurum, Cyclops vicinus, Thermocyclops taihokuensis, Mesocyclops notius and Sinocalanus dorrii. Daphnia was rare in abundance. Canonical correspondence analysis showed that except for four species (D. hyalina, S. dorrii, C. vicinus and M. micrura), almost all the dominant species had the same preference for environmental factors. Temperature, predatory cyclopoids and planktivorous fishes seem to be the key factors determining species distribution. TP was a relatively better trophic indicator than chlorophyll a to predict crustacean biomass. Within the three groups of lakes, however, there was no consistent relationship between crustacean biomass and trophic indicators. The possible reason might be that top-down and bottom-up control on crustaceans vary with lake trophic state. The lack of significant negative correlation between crustacean biomass and chlorophyll a suggests that there was little control of phytoplankton biomass by macrozooplankton in these shallow subtropical lakes. (c) 2007 Elsevier GmbH. All rights reserved.

The giant zooxanthellae-bearing ciliate Maristentor dinoferus (Heterotrichea) is closely related to folliculinidae

The small subunit rDNA sequence of Maristentor dinoferus (Lobban, Schefter, Simpson, Pochon, Pawlowski, and Foissner, 2002) was determined and compared with sequences from other Heterotrichea and Karyorelictea. Maristentor resembles Stentor in basic morphology and had been provisionally assigned to Stentoridae. However, our phylogenetic analyses show that Maristentor is more closely related to Folliculinidae. Our results support the creation of a separate family for Maristentor, Maristentoridae n. fam., and also confirm the phylogenetic grouping of Folliculindae, Stentoridae, Blepharismidae, and Maristentoridae, which we informally call 'stentorids'. Maristentor, rather than Stentor itself, appears to be most significant in understanding the origins of folliculinids from their aloricate ancestors. Our analyses suggest continued uncertainty in the exact placement of the root of heterotrichs with this phylogenetic marker.

Electron mobility related to scattering caused by the strain variation of AlGaN barrier layer in strained AlGaN/GaN heterostructures

Using the measured capacitance- voltage curves of Ni Schottky contacts with different areas on strained AlGaN/ GaN heterostructures and the current- voltage characteristics for the AlGaN/ GaN heterostructure field- effect transistors at low drain- source voltage, we found that the two- dimensional electron gas (2DEG) electron mobility increased as the Ni Schottky contact area increased. When the gate bias increased from negative to positive, the 2DEG electron mobility for the samples increased monotonically except for the sample with the largest Ni Schottky contact area. A new scattering mechanism is proposed, which is based on the polarization Coulomb field scattering related to the strain variation of the AlGaN barrier layer. (C) 2007 American Institute of Physics.