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11.
Meuser JE D'Adamo S Jinkerson RE Mus F Yang W Ghirardi ML Seibert M Grossman AR Posewitz MC 《Biochemical and biophysical research communications》2012,417(2):704-709
Chlamydomonas reinhardtii (Chlamydomonas throughout) encodes two [FeFe]-hydrogenases, designated HYDA1 and HYDA2. While HYDA1 is considered the dominant hydrogenase, the role of HYDA2 is unclear. To study the individual functions of each hydrogenase and provide a platform for future bioengineering, we isolated the Chlamydomonas hydA1-1, hydA2-1 single mutants and the hydA1-1 hydA2-1 double mutant. A reverse genetic screen was used to identify a mutant with an insertion in HYDA2, followed by mutagenesis of the hydA2-1 strain coupled with a H(2) chemosensor phenotypic screen to isolate the hydA1-1 hydA2-1 mutant. Genetic crosses of the hydA1-1 hydA2-1 mutant to wild-type cells allowed us to also isolate the single hydA1-1 mutant. Fermentative, photosynthetic, and in vitro hydrogenase activities were assayed in each of the mutant genotypes. Surprisingly, analyses of the hydA1-1 and hydA2-1 single mutants, as well as the HYDA1 and HYDA2 rescued hydA1-1 hydA2-1 mutant demonstrated that both hydrogenases are able to catalyze H(2) production from either fermentative or photosynthetic pathways. The physiology of both mutant and complemented strains indicate that the contribution of HYDA2 to H(2) photoproduction is approximately 25% that of HYDA1, which corresponds to similarly low levels of in vitro hydrogenase activity measured in the hydA1-1 mutant. Interestingly, enhanced in vitro and fermentative H(2) production activities were observed in the hydA1-1 hydA2-1 strain complemented with HYDA1, while maximal H(2)-photoproduction rates did not exceed those of wild-type cells. 相似文献
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目的:分别克隆人细小病毒B19三个主要蛋白VP1、VP2、NS1全长基因,构建真核表达载体。方法:利用PCR和分子克隆技术,分别将B19病毒vp1、vp2、ns1基因全长片段扩增后,构建带荧光标签的真核表达载体;在人体细胞中表达并通过荧光、RT-PCR和Western Blot、测序等方法鉴定。结果:成功构建了包含B19病毒vp1、vp2、ns1全长基因,并在人体细胞中表达了VP1、VP2、NS1蛋白。结论:人微小病毒B19三个主要蛋白基因得到克隆和表达,为进行相关的研究奠定了基础。 相似文献
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SUMMARY OF GREEN PLANT PHYLOGENY AND CLASSIFICATION 总被引:7,自引:0,他引:7
Abstract— A cladogram of green plants involving all major extant groups of green algae, bryophytes, pteridophytes, and seed plants is presented. It is partly based on contributions by B. Mishler and S. Churchill, H. Wagner, and P. Crane. The relationships of green plants to other green organisms ( Prochloron , euglenophytes) are discussed. The characters and subclades of the cladogram are briefly discussed, with an attempt to indicate weak points. The possibility of including some major extinct groups is considered. A cladistic classification consistent with the cladogram is presented. Grades are abandoned as taxa and major clades like the division Chlorophyta (green algae excluding micro-monadophytes and charophytes sensu Mattox and Stewart), the division Streptophyta (charophytes + embryophytes), the subdivision Embryophytina (land plants or embryophytes), the superclass Tracheidatae (tracheophytes), and the class Spermatopsida (seed plants) are recognized. 相似文献
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NICOLAS LAMOUROUX JEAN-MICHEL OLIVIER HERVÉ CAPRA MARC ZYLBERBLAT RE CHANDESRIS PASCAL ROGER 《Freshwater Biology》2006,51(9):1730-1743
1. Many aspects of the flow regime influence the structure of stream communities, among which the minimum discharge left in rivers has received particular attention. However, instream habitat models predicting the ecological impacts of discharge management often lack biological validation and spatial generality, particularly for large rivers with many fish species. 2. The minimum flow at Pierre‐Bénite, a reach of the Rhône river bypassed by artificial channels, was increased from 10 to 100 m3 s?1 in August 2000 (natural mean discharge 1030 m3 s?1), resulting in a fivefold increase in average velocity at minimum flow. Fish were electrofished in several habitat units on 12 surveys between 1995 and 2004. 3. Principal components analysis revealed a significant change in the relative abundance of fish species. The relative abundance of species preferring fast‐flowing and/or deep microhabitats increased from two‐ to fourfold after minimum flow increase. A change in community structure confirmed independent quantitative predictions of an instream habitat model. This change was significantly linked to minimum flow increase, but not to any other environmental variables describing high flows or temperature at key periods of fish life cycle. The rapidity of the fish response compared with the lifespan of individual species can be explained by a differential response of specific size classes. 4. The fish community at Pierre‐Bénite is in a transitional stage and only continued monitoring will indicate if the observed shift in community structure is perennial. We expect that our case study will be compared with other predictive tests of the impacts of flow restoration in large rivers, in the Rhône catchment and elsewhere. 相似文献
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We have studied the effect of sodium orthovanadate, an inhibitor of protein tyrosine phosphatases, on primary cultures of colonocytes and stromal cells. Everted proximal and distal colonic tissue of adult rats were disintegrated by a collagenase/dispase solution for 60 min at 37°C to prepare viable gland fragments and isolated cells. Cell preparations were inoculated onto plastic substratum or cytodex-3 microcarriers in a defined maintenance medium or in 1% fetal calf serum media. Incorporation of sodium orthovanadate (≥50 μm) in these media constantly enhanced the survival (cell enumeration and trypan blue exclusionP<0.05) and the adhesion (up to four-fold by crystal violet staining,P<0.01) of colonocytes (characterized by cytokeratin-18, transforming growth factor-α or alkaline phosphatase expression) and stromal cells. Removal of sodium orthovanadate from culture media restored cellular death processes. Incorporation of 10 mmn-butyric acid did not promote cell adhesion and survival except for distal cells exposed to 2 mm sodium orthovanadate. Besides studies in the regulation of anoikis in primary culture, the model will help to assay the influences of dietary and growth factors on the biology of non-cancerous colonic cells. 相似文献
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MAXIME LAVOIE PIERRE-YVES COLLIN FLORENT LEMIEUX HÉLÈNE JOLICOEUR PIERRE CANAC-MARQUIS SERGE LARIVIÈRE 《The Journal of wildlife management》2009,73(6):870-875
ABSTRACT In Quebec, Canada, harvest of bobcats (Lynx rufus) started to decline in 1985 and by 1991, harvest seasons were closed due to concerns of a perceived population decline. Since the closing of harvest season in 1991, the average temperature has increased, snow quantity has decreased, and important changes in agriculture and forest management have occurred. In light of changing conditions, the situation of Quebec bobcats needed reassessment. Thus, we analyzed harvest data to clarify the current status of bobcat populations in Quebec. From 1980 to 1991, bobcat harvest in Quebec was strongly correlated with bobcat harvest in Maine (USA), Nova Scotia (Canada), Ontario (Canada), and Vermont (USA). Extrapolations of harvest in Quebec relative to harvest in Maine, Ontario, Vermont, and Nova Scotia suggested an increase in number of bobcats after 1991. Mass of male and female bobcats before 1991 was less than mass of animals captured after 1991. Percentage of juveniles in the reported harvest before 1991 was higher than after 1991. However, percentage of males and litter sizes in the harvest did not differ before and after 1991. The geographic distribution of bobcats captured has gradually expanded after the closure of the harvest season. Our findings suggest that bobcat populations in Quebec have recovered from the 1985–1991 decline, and that the harvest season for this species could resume. This study also illustrates how managers can rely on data from neighboring jurisdiction to manage species when local harvest data is unavailable. 相似文献
20.
FRANÇOIS X. CÔTE † SERGE GALZI † MICHEL FOLLIOT YANNICK LAMAGNÈRE PIERRE-YVES TEYCHENEY MARIE-LINE ISKRA-CARUANA 《Molecular Plant Pathology》2010,11(1):137-144
The genome of Musa balbisiana spp. contains several infectious endogenous sequences of Banana streak virus (eBSV). We have shown previously that in vitro micropropagation triggers the activation of infectious eBSOLV (endogenous sequences of Banana streak Obino l'Ewai virus ) in the synthetic tetraploid interspecific hybrid FHIA21 (AAAB). In this work, we show that another synthetic tetraploid (AAAB) hybrid and two natural triploid (AAB) plantains are equally prone to the activation of infectious eBSOLV during tissue culture. These results are a strong indication that such activation is a general phenomenon in interspecific Musa cultivars, whether synthetic or natural. We also report the first in-depth study of the correlation between the duration of tissue culture and the level of activation of infectious eBSOLV, and show that specific and common activation patterns exist in these banana plants. We hypothesize that these patterns result from the concomitant activation of infectious eBSOLV and a decrease in the virus titre in neoformed plantlets, resulting from cell multiplication outcompeting virus replication. We provide experimental data supporting this hypothesis. No activation of infectious eBSGFV (endogenous sequences of Banana streak Goldfinger virus) by tissue culture was observed in the two natural AAB plantain cultivars studied here, whereas such activation occurred in the AAAB synthetic hybrid studied. We demonstrate that this differential activation does not result from differences in the structure of eBSGFV, as all banana genomes harbour eaBSGFV-7. 相似文献