Thermal and Structural Stability of Adsorbed Proteins

Experimental evidence suggests that proteins adsorbed to hydrophobic surfaces at low coverages are stabilized relative to the bulk. For larger coverages, proteins unfold and form β-sheets. We performed computer simulations on model proteins and found that: 1), For weakly adsorbing surfaces, unfolded conformations lose more entropy upon adsorption than folded ones. 2), The melting temperature, both in the bulk and at surfaces, decreases with increasing protein concentration because of favorable interprotein interactions. 3), Proteins in the bulk show large unfolding free energy barriers; this barrier decreases at stronger adsorbing surfaces. We conjecture that typical experimental temperatures appear to be below the bulk melting temperature for a single protein, but above the melting temperature for concentrated protein solutions. Purely thermodynamic factors then explain protein stabilization on adsorption at low concentrations. However, both thermodynamic and kinetic factors are important at higher concentrations. Thus, proteins in the bulk do not denature with increasing concentration due to large kinetic barriers, even though the aggregated state is thermodynamically preferred. However, they readily unfold upon adsorption, with the surface acting as a heterogeneous catalyst. The thermal behavior of proteins adsorbed to hydrophobic surfaces thus appears to follow behavior independent of their chemical specificity.     

Operations for portal hypertension due to extrahepatic obstruction: results and 10 year follow up.

Between 1976 and 1984, 136 patients with portal hypertension due to extrahepatic obstruction were operated on. Twenty two patients had emergency and 114 elective operations. The operative mortality was 9% and 1%, respectively. Altogether 117 patients (86%) were followed up for from two to 10 years: 17 rebled, none developed encephalopathy or sepsis after splenectomy, and 90% and 75% were alive at five and 10 years respectively. Unlike endoscopic sclerotherapy and treatment with propranolol, operative treatment of variceal bleeding can usually be completed during one admission and carries a low mortality and a fairly low morbidity. Operation seems to be the best form of treatment for poor patients living far from medical facilities in developing countries and may be the treatment of choice in developed countries as well.     

Mechanism of interferon action. Expression of vesicular stomatitis virus G gene in transfected COS cells is inhibited by interferon at the level of protein synthesis

The effect of interferon on the expression of the vesicular stomatitis virus glycoprotein G gene was examined in simian COS cells transfected with the expression vector pSVGL containing the G gene under the control of the SV40 late promoter. When COS cells were treated with interferon 24 h after transfection, the synthesis of vesicular stomatitis virus G protein was inhibited by about 80% as compared to that in untreated controls. By contrast, under the same conditions, neither the plasmid copy number nor the G gene mRNA levels were detectably affected by interferon treatment. Likewise, the synthesis of simian virus 40 large T-antigen was not inhibited by interferon treatment of transfected COS cells even though the synthesis of vesicular stomatitis virus G protein was markedly inhibited. The residual G protein synthesized in transfected, interferon-treated COS cells appeared to be normally glycosylated.     

Molecular detection of Candidatus Phytoplasma spp. causing witches’ broom disease of acid lime (Citrus aurantifolia) in India

Phytoplasma infected acid lime plants in India develop characteristic symptoms like small chlorotic leaves, multiple sprouting and shortened internodes. Leaves drop prematurely and infected branches have distorted twigs resembling witches’ broom appearance which eventually show die-back symptoms. During its first report in 1999, witches’ broom disease identification was made on the basis of symptomatology and electron microscopy. However, molecular techniques have proved to be more accurate and reliable for phytoplasma detection than the conventional methods. During survey in the year 2010 six samples were collected from infected acid lime plants showing typical field symptoms from Vidarbha region of Maharastra. Initially, phytoplasma bodies were observed in phloem tissues of all six symptomatic samples under JEM 100S transmission electron microscope and all these six samples were subsequently screened using different set of phytoplasma specific universal primers by nested PCR, a widely recommended molecular technique for phytoplasma detection. In the present study P1/P7 “universal” phytoplasma-primer set was used for first round of PCR and amplified products were processed separately for nested PCR with three different nested primer pairs viz. R16F2n/R16R2, R16mF2/R16mR1 and fU5/rU3. The presence of phytoplasma was confirmed in all six suspected samples and one representative ~1.2 kb size amplicon was sequenced and deposited in GenBank as Candidatus Phytoplasma species AL-M (JQ808143). This is the first report of PCR based molecular detection of phytoplasma-induced witches’ broom disease of acid lime (WBDL) in India. Further molecular evaluation to determine the identity to the species level is in progress.     

Fungi causing plant diseases at jabalpur (madhya pradesh)-IX

Summary The present paper describes 6 foliicolous fungi from Jabalpur (India). These includeAsterina lawsoniae Syd. on leaves ofLawsonia alba, Diplocarpon rosae Wolf. onRosa sp.,Cercospora jujubae Chowdhury onZizyphus jujuba andCercospora subsessilis Henn. &Nym. onAzadirachta indica, new fungus records for Madhya Pradesh;Asterostomella strophanti Henn. on leaves ofFlacourtia ramontchii, a new fungus for the country andCorynespora cassiicola (Berk. &Curt.)Wei. onClerodendron inerme, a new host record.     

MicroRNA-424 regulates the expression of CX3CL1 (fractalkine) in human microvascular endothelial cells during Rickettsia rickettsii infection

Cytokines and chemokines trigger complex intracellular signaling through specific receptors to mediate immune cell recruitment and activation at the sites of infection. CX3CL1 (Fractalkine), a membrane-bound chemokine also capable of facilitating intercellular interactions as an adhesion molecule, contributes to host immune responses by virtue of its chemoattractant functions. Published studies have documented increased CX3CL1 expression in target tissues in a murine model of spotted fever rickettsiosis temporally corresponding to infiltration of macrophages and recovery from infection. Because pathogenic rickettsiae primarily target vascular endothelium in the mammalian hosts, we have now determined CX3CL1 mRNA and protein expression in cultured human microvascular endothelial cells (HMECs) infected in vitro with Rickettsia rickettsii. Our findings reveal 15.5 ± 4.0-fold and 12.3 ± 2.3-fold increase in Cx3cl1 mRNA expression at 3 h and 24 h post-infection, coinciding with higher steady-state levels of the corresponding protein in comparison to uninfected HMECs. Since CX3CL1 is a validated target of microRNA (miR)-424-5p (miR-424) and our earlier findings demonstrated robust down-regulation of miR-424 in R. rickettsii-infected HMECs, we further explored the possibility of regulation of CX3CL1 expression during rickettsial infection by miR-424. As expected, R. rickettsii infection resulted in 87 ± 5% reduction in miR-424 expression in host HMECs. Interestingly, a miR-424 mimic downregulated R. rickettsii-induced expression of CX3CL1, whereas an inhibitor of miR-424 yielded a converse up-regulatory effect, suggesting miR-424-mediated regulation of CX3CL1 during infection. Together, these findings provide the first evidence for the roles of a host microRNA in the regulation of an important bifunctional chemokine governing innate immune responses to pathogenic rickettsiae.