We have developed a general model that relates the lateral diffusion coefficient of one isolated large intrinsic molecule (mol. wt. ?1000) in a phosphatidylcholine bilayer to the static lipid hydrocarbon chain order. We have studied how protein lateral diffusion can depend upon protein-lipid interactions but have not investigated possible non-specific contributions from gel-state lattice defects. The model has been used in Monte Carlo simulations or in mean-field approximations to study the lateral diffusion coefficients of Gramicidin S, the M-13 coat protein and glycophorin in dimyristoyl- and dipalmitoylphosphatidylcholine (DMPC and DPPC) bilayers as functions of temperature. Our calculated lateral diffusion coefficients for Gramicidin S and the M-13 coat protein are in good agreement with what has been observed and suggest that Gramicidin S is in a dimeric form in DMPC bilayers. In the case of glycophorin we find that the ‘ice breaker’ effect can be understood as a consequence of perturbation of the lipid polar region around the protein. In order to understand this effect is is necessary that the protein hydrophilic section perturb the polar regions of at least approx. 24 lipid molecules, in good agreement with the numbers of 29–30 measured using 31P-NMR. Because of lipid-lipid interactions this effect extends itself out to four or five lipid layers away from the protein so that the hydrocarbon chains of between approx. 74 and approx. 108 lipid molecules are more disordered in the gel phase, so contributing less to the transition enthalpy, in agreement with the numbers of 80–100 deduced from differential scanning calorimetry (DSC). An understanding of the abrupt change in the diffusion coefficient at a temperature below the main bilayer transition temperature requires an additional mechanism. We propose that this change may be a consequence of a ‘coupling-uncoupling’ transition involving the protein hydrophilic section and the lipid polar regions, which may be triggered by the lipid bilayer pretransition. Our calculation of the average number of gauche bonds per lipid chain as a function of temperature and distance away from an isolated polypeptide or integral protein shows the extent of statically disordered lipid around such molecules. The range of this disorder depends upon temperature, particularly near the main transition. 相似文献
Iron deficiency is one of the most prevailing micronutrient deficiencies throughout the globe. Iron malnutrition affects billions of people around the world especially children and pregnant women. Its deficiencies can be overcome through microbial biofortification: a process of deliberately increasing desirable nutrients in crop plants. Plant growth-promoting rhizobacteria (PGPR) can improve iron content in edible plant tissues through different direct and indirect mechanisms. Adding plant growth regulators along with rhizobacteria makes it a novel fortification approach. In the current experiment, the interactive effect of two bacterial isolates (O-13 & K-10) alone and in consortium with l-tryptophan in the presence of iron sulfate was evaluated on growth, physiology, tuber characteristics, and iron concentration in potato (Solanum tuberosum L.). Results revealed that inoculation with PGPR and plant growth regulator (PGR) significantly improved the plant height, straw yield, and the number of tubers per plant. Potato (Solanum tuberosum L.) tuber characteristics (starch content, vitamin-C, relative water content) were also improved significantly. O-13, K-10, and l-tryptophan had significantly improved the iron concentration up to 20.59, 33.12, and 28.95%, respectively. However, inoculation with the microbial consortium and l-tryptophan showed a significant increase of up to one-fold in the iron concentration of potato (Solanum tuberosum L.) as compared with uninoculated control. The results suggest that rhizobacteria can help the plant to uptake nutrients from the soil. These findings concluded on the fact that the interactive effect of microbial assisted biofortification and plant growth regulator is a novel, promising, and cost-effective approach to mitigate micronutrient deficiencies especially in resource-limited countries.
Human parechoviruses are known to cause asymptomatic to severe clinical illness predominantly respiratory and gastroenetric infections. Despite their global prevalence, epidemiological studies have not been performed in Pakistan. In this study, we retrospectively analyzed 110 fecal specimen and found 26 (24%) positive for viral RNA with HPeV-10 (n = 3, 23%), HPeV-13 (n = 4, 31%) and HPeV-15 (n = 6, 46%) genotypes. Clinical features of patients with different HPeV genotypes were compared. All HPeV positive children were aged ≤4 years (mean 13.92 months). The male-to-female ratio was 1: 1.17 (46.2 vs 53.8%) with significant association (p = .031) to HPeV infectivity. HPeV-10 and -13 were found during summer while HPeV-15 was only detected during late winter season. Disease symptoms were more severe in children infected with HPeV-10 and -13 as compared to HPeV-15. Fever and vomiting were observed in 100% cases of HPeV-10 and -13 while only 17% patients of HPeV-15 had these complaints. Phylogenetic analyses showed that HPeV-10, -13 and -15 strains found in this study have 9–13%, 16.8% and 21.8% nucleotide divergence respectively from the prototype strains and were clustered to distinct genetic lineages. This is the first report of HPeV-15 infection in humans although first identified in rhesus macaques. The arginine-glycine-aspartic acid (RGD) motif present at the C-terminal of VP1 responsible for the viral attachment to cellular integrins was not found in all of these strains. In conclusion, these findings enhance our knowledge related to the epidemiology and genetic diversity of the HPeV in Pakistan and support the need for continued laboratory based surveillance programs especially in infants and neonatal clinical settings. Further, the parechovirus pathogenesis, cross-species transmission and disease reservoirs must be ascertained to adopt better prevention measures. 相似文献
Extremophiles - The gene-encoding Indole-3-glycerol phosphate synthase, a key enzyme involved in the cyclization of 1-(o-carboxyphenylamino)-1-deoxyribulose 5-phosphate, from Pyrococcus furiosus... 相似文献
In soil biota, higher and enduring concentration of heavy metals like cadmium (Cd) is hazardous and associated
with great loss in growth, yield, and quality parameters of most of the crop plants. Recently, in-situ applications of
eco-friendly stabilizing agents in the form of organic modifications have been utilized to mitigate the adverse
effects of Cd-toxicity. This controlled experiment was laid down to appraise the imprints of various applied
organic amendments namely poultry manure (PM), farmyard manure (FYM), and sugarcane press mud (PS)
to immobilize Cd in polluted soil. Moreover, phytoavailability of Cd in wheat was also accessed under an alkaline
environment. Results revealed that the addition of FYM (5–10 ton ha-1
) in Cd-contaminated soil significantly
increased germination rate, leaf chlorophyll content, plant height, spike length, biological and grain yield amongst
all applied organic amendments. Moreover, the addition of FYM (5–10 ton ha-1
) also reduced the phytoavailability of Cd by 73–85% in the roots, 57–83% in the shoots, and 81–90% in grains of wheat crop. Thus, it is affirmed
that incorporation of FYM (5–10 ton ha-1
) performed better to enhance wheat growth and yield by remediating
Cd. Thus, the application of FYM (5–10 ton ha-1
) reduced the toxicity induced by Cd to plants by declining its
uptake and translocation as compared to all other applied organic amendments to immobilize Cd under sandy
alkaline polluted soil. 相似文献
In wireless network research, simulation is the most imperative technique to investigate the network’s behavior and validation. Wireless networks typically consist of mobile hosts; therefore, the degree of validation is influenced by the underlying mobility model, and synthetic models are implemented in simulators because real life traces are not widely available. In wireless communications, mobility is an integral part while the key role of a mobility model is to mimic the real life traveling patterns to study. The performance of routing protocols and mobility management strategies e.g. paging, registration and handoff is highly dependent to the selected mobility model. In this paper, we devise and evaluate the Show Home and Exclusive Regions (SHER), a novel two-dimensional (2-D) Colored Petri net (CPN) based formal random mobility model, which exhibits sociological behavior of a user. The model captures hotspots where a user frequently visits and spends time. Our solution eliminates six key issues of the random mobility models, i.e., sudden stops, memoryless movements, border effect, temporal dependency of velocity, pause time dependency, and speed decay in a single model. The proposed model is able to predict the future location of a mobile user and ultimately improves the performance of wireless communication networks. The model follows a uniform nodal distribution and is a mini simulator, which exhibits interesting mobility patterns. The model is also helpful to those who are not familiar with the formal modeling, and users can extract meaningful information with a single mouse-click. It is noteworthy that capturing dynamic mobility patterns through CPN is the most challenging and virulent activity of the presented research. Statistical and reachability analysis techniques are presented to elucidate and validate the performance of our proposed mobility model. The state space methods allow us to algorithmically derive the system behavior and rectify the errors of our proposed model. 相似文献
The present study was conducted to examine the changes in some key metabolites in drought-stressed sunflower plants supplied
with glycine betaine externally. Imposition of drought stress at the vegetative or reproductive growth stages decreased the
plant dry matter production and increased the accumulation of organic solutes (glycine betaine, proline, soluble proteins,
free amino acids and soluble sugars) in two sunflower lines, i.e., Glushan-98 and Suncross. In general, decrease in dry matter
production and increase in the endogenous levels of organic solutes, were more pronounced when drought stress applied at the
vegetative stage than at the reproductive stage. Glycine betaine applied as a pre-sowing seed treatment was not found to be
effective in reducing the negative effects of drought stress in sunflower plants. Foliar application of GB further enhanced
the leaf endogenous levels of GB, soluble proteins and total soluble sugars in drought stressed plants without exerting any
negative effects on other osmotica. However, this GB-induced increase in endogenous levels of organic solutes was found to
be not associated with plant dry matter production under stress conditions. 相似文献