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81.
The change in stored carbon (C) stocks was assessed for a 700 km2 areawhere forest cover decreased from 60% to 10% in the last 30 years. At the same time, the area under coffee increased from 7% to 70% with a gradual evolution from open "sun coffee" systems to multi-strata "shade coffee" systems that providea partial compensation for C loss. The use of a generic tropical forest rather than tree-specific allometric equation can lead to substantial (up to 100%) overestimates of aboveground biomass depending on wood density and tree shape. The shoot:root ratio (biomass) of coffee shifted with age, from the 4:1 value often assumed for tropical trees to 2:1. Annual aboveground C stock accumulation rates during the establishment stage after slash-and- burn land clearing were 1, closeto 2 or 3.5 Mg C ha-1a-1 for sun coffee, shade coffee and fallow regrowth, respectively. Forest remnants, shade coffee and sun coffee had soil C stocks in the upper 30 cm of the soil that were 79%, 60% or 45%, respectively, of the values expected for primary forest in Sumatra. Total C stock (time averaged, above - 0.3m in the soil) for forest, shade and sun coffee was 262, 82 and 52 Mg C ha-1, respectively. In the 1970-1984 period, while forest cover was reduced from 59.5%to 19.7%, the landscape lost on average 6.8 Mg C ha-1 a-1. In the 1984-2000 period forest cover was further reduced to 12.6%, but the landscape lost only 0.39Mg C ha-1 a-1, as forest loss was partially compensated by an increase in shadecoffee systems. Conversion of all current sun coffee to shade coffee systems while protecting the remaining forest, could increase average landscape level C stocks by 10 Mg ha-1 over a time frame of say 20 years, or 0.5 Mg C ha-1 a-1.  相似文献   
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Summary The complete nucleotide sequence of the genes encoding the Rieske FeS, the cytochrome b and the cytochrome c 1 subunits of the ubiquinol-cytochrome c 2 oxidoreductase from the photosynthetic purple bacterium Rhodopseudomonas viridis, and the derived amino acid sequences are presented. These three genes, fbcF, fbcB and fbcC, are located at contiguous sites of the genome. The DNA-deduced amino acid sequences are compared with known primary structures of corresponding proteins from other purple photosynthetic bacteria, as well as mitochondria, cyanobacteria and chloroplasts.Abbreviations BSA bovine serum albumin - Rb Rhodobacter - Rps Rhodopseudomonas  相似文献   
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Membrane fractions prepared from smooth muscle of the pig stomach (antral part) contain two Ca2+-dependent phosphoprotein intermediates belonging to different Ca2+-transport ATPases. These alkali-labile phosphoproteins can be separated by electrophoresis in acid medium. The 130 kDa phosphoprotein resembles a corresponding protein in the erythrocyte membrane, whereas the 100 kDa protein resembles that of the Ca2+-transport ATPase in sarcoplasmic reticulum from skeletal muscle. These resemblances are expressed in terms of Mr, reaction to La3+ and in a similar proteolytic degradation pattern. The presence of the calmodulin-stimulated ATPase in mixed membranes from smooth muscle is confirmed by its binding of calmodulin and antibodies against erythrocyte Ca2+-transport ATPase, whereas such binding does not occur with proteins present in the presumed endoplasmic reticulum from smooth muscle.  相似文献   
87.
Latex of all Vasconcellea species analyzed to date exhibits higher proteolytic amidase activities, generally attributed to cysteine proteinases, than the latex of Carica papaya. In the present study, we show that this higher activity is correlated with a higher concentration of enzymes in the latex of Vasconcellea fruits, but in addition also results from the presence of other cysteine proteinases or isoforms. In contrast to the cysteine proteinases present in papaya latex, which have been extensively studied, very little is known about the cysteine proteinases of Vasconcellea spp. In this investigation, several cDNA sequences coding for cysteine proteinases in Vasconcellea x heilbornii and Vasconcellea stipulata were determined using primers based on conserved sequences. In silico translation showed that they hold the characteristic features of all known papain-class cysteine proteinases, and a phylogenetic analysis revealed the existence of several papain and chymopapain homologues in these species. Ion-exchange chromatography and gel filtration procedures were applied on latex of V. x heilbornii in order to characterize its cysteine proteinases at the protein level. Five major protein fractions (VXH-I-VXH-V) revealing very high amidase activities (between 7.5 and 23.3 nkat x mg protein(-1)) were isolated. After further purification, three of them were N-terminally sequenced. The observed microheterogeneity in the N-terminal and cDNA sequences reveals the presence of several distinct cysteine proteinase isoforms in the latex of Vasconcellea spp.  相似文献   
88.
RNAi from plants to nematodes   总被引:10,自引:0,他引:10  
Coincident with the award of the Nobel Prize for Medicine in 2006 to Fire and Mello for their discovery of RNAi, plant scientists have succeeded in using RNAi-based techniques to control nematodes, a hitherto unmanageable plant parasite. Recent work has demonstrated that the expression in a host plant of double-stranded RNA targeting housekeeping or parasitism genes in the root-knot nematode resulted in resistance to nematode infection.  相似文献   
89.
BackgroundEmerging and future SARS-CoV-2 variants may jeopardize the effectiveness of vaccination campaigns. Therefore, it is important to know how the different vaccines perform against diverse SARS-CoV-2 variants.Methods and findingsIn a prospective cohort of 165 SARS-CoV-2 naive health care workers in the Netherlands, vaccinated with either one of four vaccines (BNT162b2, mRNA-1273, AZD1222 or Ad26.COV2.S), we performed a head-to-head comparison of the ability of sera to recognize and neutralize SARS-CoV-2 variants of concern (VOCs; Alpha, Beta, Gamma, Delta and Omicron). Repeated serum sampling was performed 5 times during a year (from January 2021 till January 2022), including before and after booster vaccination with BNT162b2. Four weeks after completing the initial vaccination series, SARS-CoV-2 wild-type neutralizing antibody titers were highest in recipients of mRNA-1273, followed by recipients of BNT162b2 (geometric mean titers (GMT) of 358 [95% CI 231–556] and 214 [95% CI 153–299], respectively; p<0.05), and substantially lower in those vaccinated with the adenovirus vector-based vaccines AZD1222 and Ad26.COV2.S (GMT of 18 [95% CI 11–30] and 14 [95% CI 8–25] IU/ml, respectively; p<0.001). VOCs neutralization was reduced in all vaccine groups, with the greatest reduction in neutralization GMT observed against the Omicron variant (fold change 0.03 [95% CI 0.02–0.04], p<0.001). The booster BNT162b2 vaccination increased neutralizing antibody titers for all groups with substantial improvement against the VOCs including the Omicron variant. We used linear regression and linear mixed model analysis. All results were adjusted for possible confounding of age and sex. Study limitations include the lack of cellular immunity data.ConclusionsOverall, this study shows that the mRNA vaccines appear superior to adenovirus vector-based vaccines in inducing neutralizing antibodies against VOCs four weeks after initial vaccination and after booster vaccination, which implies the use of mRNA vaccines for both initial and booster vaccination.

Marit J. van Gils and colleagues investigate antibody responses against diverse emerging SARS-CoV-2 variants induced by four different SARS-CoV-2 vaccines in health care workers in the Netherlands.  相似文献   
90.
The purified calmodulin dependent (Ca2+ + Mg2+)-ATPase (CaMg ATPase) from porcine antral smooth muscle transports Ca2+ after reconstitution in lipid vesicles indicating that this enzyme is indeed a Ca2+-transport ATPase. For CaMg ATPase reconstituted in asolectin vesicles a good correlation was found between the time course of Ca2+ accumulation and the corresponding changes in CaMg ATPase activity. The ATPase activity was stimulated 8-fold by A23187, which further indicates a tight coupling between ATP hydrolysis and Ca2+ transport. Asolectin vesicles with incorporated enzyme accumulated Ca2+ with a ratio approaching one Ca2+ ion transported for each ATP hydrolyzed. For CaMg ATPase reconstituted in phosphatidylcholine vesicles on the other hand, Ca2+ transport and CaMg ATPase were poorly coupled as is shown by the approximately 3.5 fold stimulation by A23187. The activity of the CaMg ATPase when reconstituted in asolectin vesicles was stimulated 1.25 fold by calmodulin while in phosphatidylcholine a value of 4.25 was obtained. The CaMg ATPase activity of the enzyme reconstituted either in asolectin or phosphatidylcholine was, after its stimulation by A23187, still further stimulated by detergent by a factor of 5.  相似文献   
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