Anti-viral triterpenes: a review

Phytochemistry Reviews - Triterpenes are naturally occurring derivatives biosynthesized following the isoprene rule of Ruzicka. The triterpenes have been reported to possess a wide range of...     

Unravelling the emerging threats of microplastics to agroecosystems

Reviews in Environmental Science and Bio/Technology - In the past few decades, pollution from microplastics has emerged as an important issue on a global scale. These plastic particles are mainly...     

Field performance of bacterial inoculants to alleviate water stress effects in wheat (Triticum aestivum L.)

Plant and Soil - Plant growth promoting bacteria (PGPB) containing 1-aminocyclopropane-1-carboxylate (ACC) deaminase can play an important role in abiotic stress tolerance in plants, particularly...     

A Multivariate Method for the Parameter Estimation in Biorhythms

A suitable multivariate method is described for the periodic observations of a group of individuals having comparable periods and amplitudes. Simultaneous confidence region can be obtained for the parameters of the group as a whole instead of an individual. The study of periodic behaviour of a group is more realistic than the study of the behaviour of an individual. An application of human leucocyte counts in microfilariasis (W. bancrofti) infection has been described.     

Occurrence and distribution of rhizobiophages in Indian soils.

Soil samples from 30 fields in neighbouring districts of Varanasi were screened for rhizobiophages on 60 Rhizobium strains. Plaques were observed on five strains: P1, P5, SU391 (R. leguminosarum), CB756 and 32H1 (Rhizobium sp.). Rhizobiophages infective on one or more of the five strains were present in all fields. There seems to be no correlation between presence of phage and the standing crop or the pH (7.1-8.2) of the soil. Eight distinct rhizobiophages have been isolated and characterized for host specificity, plaque morphology and maximum titer in broth.     

An endoplasmic reticulum protein implicated in chaperoning peptides to major histocompatibility of class I is an aminopeptidase

gp96, an abundant peptide-binding chaperone of the lumen of the endoplasmic reticulum and an acceptor of peptides transported into the endoplasmic reticulum through transporter associated with antigen processing, is shown to be an aminopeptidase. gp96 can trim an amino-terminal extended 19-mer precursor of the K(b)-binding VSV8 epitope for recognition by the cognate cytotoxic T lymphocyte clone. These observations support a role for gp96 in the amino-terminal trimming of extended peptides in the endoplasmic reticulum.     

Heat shock protein-chaperoned peptides but not free peptides introduced into the cytosol are presented efficiently by major histocompatibility complex I molecules

The studies reported here bear on the events in the cytosol that lead to trafficking of peptides during antigen processing and presentation by major histocompatibility complex (MHC) I molecules. We have introduced free antigenic peptides or antigenic peptides bound to serum albumin or to cytosolic heat shock proteins hsp90 (and its endoplasmic reticular homologue gp96) or hsp70 into the cytosol of living cells and have monitored the presentation of the peptides by appropriate MHC I molecules. The experiments show that (i) free peptides or serum albumin-bound peptides, introduced into the cytosol, become ligands of MHC I molecules at a far lower efficiency than peptides chaperoned by any of the heat shock proteins tested and (ii) treatment of cells with deoxyspergualin, a drug that binds hsp70 and hsp90 with apparent specificity, abrogates the ability of cells to present antigenic peptides through MHC I molecules, and introduction of additional hsp70 into the cytosol overcomes this abrogation. These results suggest for the first time a functional role for cytosolic chaperones in antigen processing.     

Adjuvanticity of alpha 2-macroglobulin, an independent ligand for the heat shock protein receptor CD91

We recently have identified CD91 as a receptor for the heat shock protein gp96. CD91 was identified initially as a receptor for alpha(2)-macroglobulin (alpha(2)M). Gp96 and alpha(2)M are both ligands for CD91. Because gp96-chaperoned peptides can prime CD8(+) T cell responses and are re-presented by APCs, we tested alpha(2)M for similar properties. Our studies show that alpha(2)M binds peptides in vitro and that the peptides, chaperoned by alpha(2)M, efficiently prime peptide-specific CD8(+) T cell responses in mice immunized with alpha(2)M-peptide complexes. Furthermore, peptides chaperoned by alpha(2)M, like those chaperoned by gp96, can be re-presented by CD91(+) APCs on their MHC I molecules. These studies demonstrate that alpha(2)M molecules, like the heat shock protein molecules, are T cell adjuvants that can channel exogenous Ags into the endogenous pathway of Ag presentaion. The remarkable similarities between an intracellular chaperone and an extracellular serum chaperone may have interesting physiological ramifications.     

Thermodynamics of replacing an alpha-helical Pro residue in the P40S mutant of Escherichia coli thioredoxin

Escherichia coli thioredoxin is a 108 amino acid oxidoreductase and contains a single Met residue at position 37. The protein contains a long alpha-helical stretch between residues 32 and 49. The central residue of this helix, Pro40, has been replaced by Ser. The stabilities of the oxidized states of two proteins, the single mutant M37L and the double mutant M37L,P40S, have been characterized by differential scanning calorimetry (DSC) and also by a series of isothermal guanidine hydrochloride (GuHCl) melts in the temperature range of 277 to 333 K. The P40S mutation was found to stabilize the protein at all temperatures upto 340 K though both proteins had similar Tm values of about 356 K. At 298 K, the M37L,P40S mutant was found to be more stable than M37L by 1.5 kcal/mol. A combined analysis of GuHCl and calorimetric data was carried out to determine the enthalpy, entropy, and heat capacity change upon unfolding. At 298 K there was a large, stabilizing enthalpic effect in P40S though significant enthalpy-entropy compensation was observed and the two proteins had similar values of deltaCp. Thus, replacement of a Pro in the interior of an alpha helix can have substantial effects on protein stability.