Coil-helix transition of polypeptide at water-lipid interface

We present the exact solution of a microscopic statistical mechanical model for the transformation of a long polypeptide between an unstructured coil conformation and an $\alpha$-helix conformation. The polypeptide is assumed to be adsorbed to the interface between a polar and a non-polar environment such as realized by water and the lipid bilayer of a membrane. The interfacial coil-helix transformation is the first stage in the folding process of helical membrane proteins. Depending on the values of model parameters, the conformation changes as a crossover, a discontinuous transition, or a continuous transition with helicity in the role of order parameter. Our model is constructed as a system of statistically interacting quasiparticles that are activated from the helix pseudo-vacuum. The particles represent links between adjacent residues in coil conformation that form a self-avoiding random walk in two dimensions. Explicit results are presented for helicity, entropy, heat capacity, and the average numbers and sizes of both coil and helix segments.Comment: 22 pages, 12 figures, accepted for publication by JSTA

Effect of Fasciola gigantica excretory secretory antigen on rat hematological indices

The present study was undertaken to investigate the effect of Fasciola gigantica excretory secretory antigen (Fg-ESA) on rat hematological indices. Fg-ESA was prepared by keeping thoroughly washed 40 F. gigantica flukes in 100 ml phosphate buffer saline (PBS) for 2 h at 37℃, and centrifuging the supernatant at 12,000 g at 4℃ for 30 min. The protein content of Fg-ESA was adjusted to 1.8 mg/ml. The rats were randomly divided into two groups of six rats each. Rats in group A received 0.5 ml of Fg-ESA intraperitoneally (i.p.) for 7 days, whereas control rats in group B received 0.5 ml of PBS i.p. for 7 days. Hemograms of both groups were studied initially and on days 0, 2, 4, 14 and 21 after the final injection of Fg-ESA or PBS. Progressive and significant (p < 0.01) declines in the values of hemoglobin, hematocrit, and total erythrocyte count were observed without significant (p > 0.05) changes in the values of mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, or mean corpuscular volume in group A. Thus, we conclude that Fg-ESA induces normocytic normochromic anemia in rats

Low-dose ultra-high-pitch computed tomography coronary angiography: identifying the optimum combination of iteration strength and radiation dose reduction strategies to achieve true submillisievert scans

PURPOSETo identify the optimum strength of advanced modeled iterative reconstruction (ADMIRE) to achieve the best subjective and objective image quality when combining three-dose reduction strategies, ultra-high-pitch computed tomography coronary angiography (FLASH CTCA; with single-dose ivabradine to lower heart rate), low tube voltage, and ADMIRE.METHODSSixty consecutive patients underwent FLASH CTCA at 100 kVp in this single-center prospective study. Single-dose ivabradine was administered to patients whose heart rate was above 75 bpm. Images were reconstructed using the three highest strengths of ADMIRE (A3, A4, and A5). Objective and subjective image quality (using a Likert scale) were evaluated in the three datasets.RESULTSThe signal strength remained unchanged but mean noise significantly reduced across the increasing strengths of ADMIRE [signal: 513.78 ± 101.7 Hounsfield units (HU) at A3, 515.6 ± 100.5 HU at A4, and 519.7 ± 107.9 HU at A5; noise: 23.4 ± 4.5 HU at A3, 20.2 ± 3.6 HU at A4, and 17.2 ± 3.3 HU at A5]. Signal-to-noise and contrast-to-noise ratios were the highest at A5, and A5 offered significantly higher Likert scores in image noise, vessel sharpness, and overall image quality than A3 or A4. Additionally, A5 did not interfere with image interpretation in any patient.CONCLUSIONUsing all three dose reduction strategies during FLASH CTCA along with single-dose ivabradine administration ensures minimal radiation exposure in daily practice. In this study, A5 datasets had the best overall subjective and objective image quality despite their “plastic appearance”. In the future, enhanced dose reduction can be obtained by further lowering tube voltages

Advances in Food Legumes Research at ICRISAT

The mandate grain legumes of ICRISAT include chickpea, pigeonpea and groundnut which are important crops of Asia and Africa. The grain legumes improvement program of ICRISAT has access to the largest collection of germplasm of these crops (20,602 accessions of chickpea, 13,771 accessions of pigeonpea, and 15,446 accessions of groundnut) available in ICRISAT genebank, state-of-the art genomics lab, Platform for Translational Research on Transgenic Crops (PTTC), precision phenotyping facilities for abiotic and biotic stresses, controlled environment facilities and a global network of research partners. The major objectives of grain legumes improvement include high yield, early maturity, resistance/tolerance to key abiotic and biotic stresses, and market preferred grain traits (size, shape and color). The crop-specific breeding objectives include suitability to machine harvesting and herbicide tolerance in chickpea, development of hybrids in pigeonpea, and enhanced oil yield and quality (high oleic content) and tolerance to aflatoxin contamination in groundnut. The crop breeding programs have been making extensive use of the germplasm, including wild species. The advances in genomics include availability of draft genome sequences, large number of molecular markers, high density genetic maps, transcriptomic resources, physical maps and molecular markers linked to genes/quantitative trait loci for key traits. There are successful examples of introgression of traits through marker-assisted backcrossing in chickpea and groundnut. Transgenics events are available for pod borer resistance in chickpea and pigeonpea and drought tolerance in groundnut. Advances have also been made in use of secondary metabolites for promotion of plant growth, control of insect pests and plant pathogens, and biofortification. The breeding materials and germplasm supplied by ICRISAT have led to release of 160 varieties of chickpea in 26 countries, 91 varieties/hybrids of pigeonpea in 19 countries and 190 varieties of groundnut in 38 countries. Many of these varieties have been adopted widely by farmers and benefitted them in sustainably improving their livilihoods

Pigeonpea improvement: An amalgam of breeding and genomic research

In the past five decades, constant research has been directed towards yield improvement in pigeonpea resulting in the deployment of several commercially acceptable cultivars in India. Though, the genesis of hybrid technology, the biggest breakthrough, enigma of stagnant productivity still remains unsolved. To sort this productivity disparity, genomic research along with conventional breeding was successfully initiated at ICRISAT. It endowed ample genomic resource providing insight in the pigeonpea genome combating production constraints in a precise and speedy manner. The availability of the draft genome sequence with a large‐scale marker resource, oriented the research towards trait mapping for flowering time, determinacy, fertility restoration, yield attributing traits and photo‐insensitivity. Defined core and mini‐core collection, still eased the pigeonpea breeding being accessible for existing genetic diversity and developing stress resistance. Modern genomic tools like next‐generation sequencing, genome‐wide selection helping in the appraisal of selection efficiency is leading towards next‐generation breeding, an awaited milestone in pigeonpea genetic enhancement. This paper emphasizes the ongoing genetic improvement in pigeonpea with an amalgam of conventional breeding as well as genomic research

Achievements and prospects of genomics-assisted breeding in three legume crops of the semi-arid tropics

Advances in next-generation sequencing and genotyping technologies have enabled generation of large-scale genomic resources such as molecular markers, transcript reads and BAC-end sequences (BESs) in chickpea, pigeonpea and groundnut, three major legume crops of the semi-arid tropics. Comprehensive transcriptome assemblies and genome sequences have either been developed or underway in these crops. Based on these resources, dense genetic maps, QTL maps as well as physical maps for these legume species have also been developed. As a result, these crops have graduated from ‘orphan’ or ‘less-studied’ crops to ‘genomic resources rich’ crops. This article summarizes above mentioned advances in genomics and genomics-assisted breeding applications in the form of marker-assisted selection (MAS) for hybrid purity assessment in pigeonpea; marker-assisted backcrossing (MABC) for introgressing QTL region for drought-tolerance related traits, Fusarium wilt (FW) resistance and Ascochyta blight (AB) resistance in chickpea; late leaf spot (LLS), leaf rust and nematode resistance in groundnut. We critically present the case of use of other modern breeding approaches like marker-assisted recurrent selection (MARS) and genomic selection (GS) to utilize the full potential of genomics-assisted breeding for developing superior cultivars with enhanced tolerance to various environmental stresses. In addition, this article recommends the use of advanced- backcross (AB-backcross) breeding and development of specialized populations such as multi-parents advanced generation intercross (MAGIC) for creating new variations that will help developing superior lines with broadened genetic base. In summary, we propose the use of integrated genomics and breeding approach in these legume crops to enhance crop productivity in marginal environments ensuring food security in developing countries

A Study to Assess the Prevalence of Herpes Simplex Type 2 (HSV-2) Infections in Pregnant Women in A Tertiary Care Hospital

Aim: Assess the prevalence of Herpes Simplex Type 2 (HSV-2) infections in pregnant women in a tertiary care hospital. Methods: There were a total of one hundred pregnant women that participated in this research. 5 ml blood samples were obtained using vein puncture and placed in a sterile plain tube. These samples were then allowed to clot for 30 minutes before being centrifuged at 3000 rpm for 5 minutes. Each of the resulting serums was placed in a fresh vial, given a label, and kept at a temperature of -20 degrees Celsius until it was time for the ELISA analysis. In order to determine whether or not the serum included HSV-2 IgG antibodies, an HSV-2 specific IgG ELISA test kit was used. Results: In this research, 100 pregnant women were recruited. HSV-2 infection was found in 40% of people. The largest infected group was pregnant women under the age of 25, with 57.14 percent infected, and the lowest in older age groups. Housewives had the greatest prevalence (71.79 percent), followed by private workers (32%), while government employees had the lowest seroprevalence (8.33 percent). The relationship between viral infection and employment was statistically significant (p≤ 0.05).&nbsp

Free-energy landscapes and insertion pathways for peptides in membrane environment

Free-energy landscapes for short peptides—specifically for variants of the pH low insertion peptide (pHLIP)—in the heterogeneous environment of a lipid bilayer or cell membrane are constructed, taking into account a set of dominant interactions and the conformational preferences of the peptide backbone. Our methodology interprets broken internal H-bonds along the backbone of a polypeptide as statistically interacting quasiparticles, activated from the helix reference state. The favored conformation depends on the local environment (ranging from polar to nonpolar), specifically on the availability of external H-bonds (with H2O molecules or lipid headgroups) to replace internal H-bonds. The dominant side-chain contribution is accounted for by residue-specific transfer free energies between polar and nonpolar environments. The free-energy landscape is sensitive to the level of pH in the aqueous environment surrounding the membrane. For high pH, we identify pathways of descending free energy that suggest a coexistence of membrane-adsorbed peptides with peptides in solution. A drop in pH raises the degree of protonation of negatively charged residues and thus increases the hydrophobicity of peptide segments near the C terminus. For low pH, we identify insertion pathways between the membrane-adsorbed state and a stable trans-membrane state with the C terminus having crossed the membrane