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The Lower Cambrian Chengjiang fauna is reviewed and shown to be closely comparable with the younger Burgess Shale fauna. but with various differences in detail. A diverse group of more or less annulated lobopod animals including 'armoured lobopods' are regarded as representatives of the phylum Onychophora. 'Trilobitomorphs' include several new types. Probable protaspides of the trilobitomorph Naraoia are described. No molluses or deuterostomes have been identified. The preservational orientations of the various taxa are reviewed and compared with orientations of the Burgess Shale taxa. Orientation in the sediment is found to be closely correlated to the original shape of individuals. Several new genera and species are described: the segmented. worm-shaped Yunnanozoon lividum gen. et sp.n., the 'armoured lobopods' Onychodictyon ferox gen. et sp.n. and Cardiodictyon catenulum gen. et sp.n. and the arthropods Saperion glumaceum gen. et sp.n., Sinoburius Iunaris gen. et sp.n., and Xandarella spectaculum gen. et sp.n. 相似文献
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David M Sintasath Nathan D Wolfe Hao Qiang Zheng Matthew LeBreton Martine Peeters Ubald Tamoufe Cyrille F Djoko Joseph LD Diffo Eitel Mpoudi-Ngole Walid Heneine William M Switzer 《Retrovirology》2009,6(1):1-17
Background
RNA interference is a gene regulatory mechanism that employs small RNA molecules such as microRNA. Previous work has shown that HIV-1 produces TAR viral microRNA. Here we describe the effects of the HIV-1 TAR derived microRNA on cellular gene expression.Results
Using a variation of standard techniques we have cloned and sequenced both the 5' and 3' arms of the TAR miRNA. We show that expression of the TAR microRNA protects infected cells from apoptosis and acts by down-regulating cellular genes involved in apoptosis. Specifically, the microRNA down-regulates ERCC1 and IER3, protecting the cell from apoptosis. Comparison to our cloned sequence reveals possible target sites for the TAR miRNA as well.Conclusion
The TAR microRNA is expressed in all stages of the viral life cycle, can be detected in latently infected cells, and represents a mechanism wherein the virus extends the life of the infected cell for the purpose of increasing viral replication. 相似文献15.
Nandini Rao Deepali Jhamb Derek J Milner Bingbing Li Fengyu Song Mu Wang S Randal Voss Mathew Palakal Michael W King Behnaz Saranjami Holly LD Nye Jo Ann Cameron David L Stocum 《BMC biology》2009,7(1):1-25
Background
For membrane proteins, lipids provide a structural framework and means to modulate function. Paired connexin hemichannels form the intercellular channels that compose gap junction plaques while unpaired hemichannels have regulated functions in non-junctional plasma membrane. The importance of interactions between connexin channels and phospholipids is poorly understood.Results
Endogenous phospholipids most tightly associated with purified connexin26 or connexin32 hemichannels or with junctional plaques in cell membranes, those likely to have structural and/or modulatory effects, were identified by tandem electrospray ionization-mass spectrometry using class-specific interpretative methods. Phospholipids were characterized by headgroup class, charge, glycerol-alkyl chain linkage and by acyl chain length and saturation. The results indicate that specific endogenous phospholipids are uniquely associated with either connexin26 or connexin32 channels, and some phospholipids are associated with both. Functional effects of the major phospholipid classes on connexin channel activity were assessed by molecular permeability of hemichannels reconstituted into liposomes. Changes to phospholipid composition(s) of the liposome membrane altered the activity of connexin channels in a manner reflecting changes to the surface charge/potential of the membrane and, secondarily, to cholesterol content. Together, the data show that connexin26 and connexin32 channels have a preference for tight association with unique anionic phospholipids, and that these, independent of headgroup, have a positive effect on the activity of both connexin26 and connexin32 channels. Additionally, the data suggest that the likely in vivo phospholipid modulators of connexin channel structure-function that are connexin isoform-specific are found in the cytoplasmic leaflet. A modulatory role for phospholipids that promote negative curvature is also inferred.Conclusion
This study is the first to identify (endogenous) phospholipids that tightly associate with connexin channels. The finding that specific phospholipids are associated with different connexin isoforms suggests connexin-specific regulatory and/or structural interactions with lipid membranes. The results are interpreted in light of connexin channel function and cell biology, as informed by current knowledge of lipid-protein interactions and membrane biophysics. The intimate involvement of distinct phospholipids with different connexins contributes to channel structure and/or function, as well as plaque integrity, and to modulation of connexin channels by lipophilic agents. 相似文献16.
LARS RAMSKÖLD 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1988,21(4):307-318
New material of early growth stages of the Silurian (Llandovery) trilobite Acernaspis is described. Pre-adult ontogenetic stages of this genus closely resemble adults of the post-Llandovery genus ***Ananaspis. A heterochronic descent of Ananaspis from Acernaspis is proposed. ***Ananaspis is interpreted as pae-domorphic, having arisen largely through neoteny. Neotenic changes already appear in the lineage in the last Acernaspis species, and Ananaspis then underwent continuous ncotcnic change throughout its known Silurian history. ▭ Heterochrony, neoteny, Silurian, Trilobita, Phacopidae, Acernaspis. Ananaspis. 相似文献
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Luís H Franco Pryscilla F Wowk Célio L Silva Ana PF Trombone Arlete AM Coelho-Castelo Constance Oliver Maria C Jamur Edson L Moretto Vânia LD Bonato 《Genetic vaccines and therapy》2008,6(1):1-11
Background
Application of plasmid DNA for immunization of food-producing animals established new standards of food safety. The addition of foreign products e.g. pDNA into the food chain should be carefully examined to ensure that neither livestock animals nor consumers develop unpredicted or undesirable side-effects.Methods
A quantitative real-time PCR (QRTPCR) methodology was developed to study the biodistribution and persistence of plasmid DNA vaccine pDNAX (pVAX-Hsp60 TM814) in mice and beef cattle. The linear quantification range and the sensitivity of the method was found to be 10 – 109 copies per reaction (500 ng/gDNA) and 3 copies per reaction, respectively.Results
Persistence of pDNAX in mice muscle tissue was restricted to injection site and the amount of pDNAX showed delivery formulation dependent (naked pDNA, electroporation, cationic liposome complexes) and mouse age-dependent clearance form injection site but pDNAX was still detectable even after 365 days. The QRTPCR analysis of various muscle tissue samples of vaccinated beef bulls performed 242–292 days after the last revaccination proved that residual pDNAX was found only in the injection site. The highest plasmid levels (up to 290 copies per reaction) were detected in the pDNAX:CDAN/DOPE group similarly to mice model. No pDNA was detected in the samples from distant muscles and draining lymph nodes.Conclusion
Quantitative real-time PCR (QRTPCR) assay was developed to assess the residual pDNA vaccine pVAX-Hsp60 TM814 in mice and beef cattle. In beef cattle, ultra low residual level of pDNA vaccine was only found at the injection site. According to rough estimation, consumption of muscles from the injection site represents almost an undetectable intake of pDNA (400 fg/g muscle tissue) for consumers. Residual plasmid in native state will hardly be found at measurable level following further meat processing. This study brings supportive data for animal and food safety and hence for further approval of pDNA vaccine field trials. 相似文献18.
中国野生印支虎及其猎物种群状况的野外实地研究一直处于空白。本研究使用足迹鉴别法、粪堆计数法,首次对西双版纳尚勇自然保护区野生印支虎种群数量现状及该区域内的虎猎物种群状况进行了调查研究。结果显示:2004 ~ 2009 年间,确认西双版纳保护区存在3 只成年印支虎个体(2 雌1 雄),西双版纳尚勇保护区拥有比较丰富的有蹄类种群,其中虎的主要猎物:水鹿平均密度为7.63 (7.40 ~ 9.23)只/ km2 ;赤麂平均密度为17. 39 (11.33 ~24.94)只/ km2 ,野猪平均密度为10.26 (7.69 ~ 14.51) 只/ km2 ,该区域虎猎物生物量为1 715. 74 kg/ km2 。本研究还探讨了该区域印支虎种群的保护前景以及中国境内开展虎种群调查的适用办法等。 相似文献
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BACKGROUND: Serological tests to detect antibodies specific to Plasmodium vivax could be a valuable tool for epidemiological studies, for screening blood donors in areas where the malaria is not endemic and for diagnosis of infected individuals. Because P. vivax cannot be easily obtained in vitro, ELISA assays using total or semi-purified antigens are rarely used. Based on this limitation, we tested whether recombinant proteins representing the 19 kDa C-terminal region of the merozoite surface protein-1 of P. vivax (MSP119) could be useful for serological detection of malaria infection. METHODS: Three purified recombinant proteins produced in Escherichia coli (GST-MSP119, His6-MSP119 and His6-MSP119-PADRE) and one in Pichia pastoris (yMSP119-PADRE) were compared for their ability to bind to IgG antibodies of individuals with patent P. vivax infection. The method was tested with 200 serum samples collected from individuals living in the north of Brazil in areas endemic for malaria, 53 serum samples from individuals exposed to Plasmodium falciparum infection and 177 serum samples from individuals never exposed to malaria. RESULTS: Overall, the sensitivity of the ELISA assessed with sera from naturally infected individuals was 95%. The proportion of serum samples that reacted with recombinant proteins GST-MSP119, His6-MSP119, His6-MSP119-PADRE and yMSP119-PADRE was 90%, 93.5%, 93.5% and 93.5%, respectively. The specificity values of the ELISA determined with sera from healthy individuals and from individuals with other infectious diseases were 98.3% (GST-MSP119), 97.7% (His6-MSP119 and His6-MSP119-PADRE) or 100% (yMSP119-PADRE). CONCLUSIONS: Our study demonstrated that for the Brazilian population, an ELISA using a recombinant protein of the MSP119 can be used as the basis for the development of a valuable serological assay for the detection of P. vivax malaria. 相似文献
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