Electrospun cellulose acetate nanofibers: The present status and gamut of biotechnological applications

Cellulose acetate (CA) has been a material of choice for spectrum of utilities across different domains ranging from high absorbing diapers to membrane filters. Electrospinning has conferred a whole new perspective to polymeric materials including CA in the context of multifarious applications across myriad of niches. In the present review, we try to bring out the recent trend (focused over last five years' progress) of research on electrospun CA fibers of nanoscale regime in the context of developmental strategies of their blends and nanocomposites for advanced applications. In the realm of biotechnology, electrospun CA fibers have found applications in biomolecule immobilization, tissue engineering, bio-sensing, nutraceutical delivery, bioseparation, crop protection, bioremediation and in the development of anti-counterfeiting and pH sensitive material, photocatalytic self-cleaning textile, temperature-adaptable fabric, and antimicrobial mats, amongst others. The present review discusses these diverse applications of electrospun CA nanofibers.     

An improved Agrobacterium-mediated transformation of recalcitrant indica rice (Oryza sativa L.) cultivars

Agrobacterium-mediated transformation of indica rice varieties has been quite difficult as these are recalcitrant to in vitro responses. In the present study, we established a high-efficiency Agrobacterium tumefaciens-mediated transformation system of rice (Oryza sativa L. ssp. indica) cv. IR-64, Lalat, and IET-4786. Agrobacterium strain EHA-101 harboring binary vector pIG121-Hm, containing a gene encoding for β-glucuronidase (GUS) and hygromycin resistance, was used in the transformation experiments. Manipulation of different concentrations of acetosyringone, days of co-culture period, bacterial suspension of different optical densities (ODs), and the concentrations of l-cysteine in liquid followed by solid co-culture medium was done for establishing the protocol. Among the different co-culture periods, 5 days of co-culture with bacterial cells (OD_600 nm?=?0.5–0.8) promoted the highest frequency of transformation (83.04 %) in medium containing l-cysteine (400 mg l^?1). Putative transformed plants were analyzed for the presence of a transgene through genomic PCR and GUS histochemical analyses. Our results also suggest that different cultural conditions and the addition of l-cysteine in the co-culture medium improve the Agrobacterium-mediated transformation frequencies from an average of 12.82 % to 33.33 % in different indica rice cultivars.     

FrnE,a Cadmium-Inducible Protein in Deinococcus radiodurans,Is Characterized as a Disulfide Isomerase Chaperone In Vitro and for Its Role in Oxidative Stress Tolerance In Vivo

Deinococcus radiodurans R1 exposed to a lethal dose of cadmium shows differential expression of a large number of genes, including frnE (drfrnE) and some of those involved in DNA repair and oxidative stress tolerance. The drfrnE::nptII mutant of D. radiodurans showed growth similar to that of the wild type, but its tolerance to 10 mM cadmium and 10 mM diamide decreased by ∼15- and ∼3-fold, respectively. These cells also showed nearly 6 times less resistance to gamma radiation at 12 kGy and ∼2-fold-higher sensitivity to 40 mM hydrogen peroxide than the wild type. In trans expression of drFrnE increased cytotoxicity of dithiothreitol (DTT) in the dsbA mutant of Escherichia coli. Recombinant drFrnE showed disulfide isomerase activity and could maintain insulin in its reduced form in the presence of DTT. While an equimolar ratio of wild-type protein could protect malate dehydrogenase completely from thermal denaturation at 42°C, the C22S mutant of drFrnE provided reduced protection to malate dehydrogenase from thermal inactivation. These results suggested that drFrnE is a protein disulfide isomerase in vitro and has a role in oxidative stress tolerance of D. radiodurans possibly by protecting the damaged cellular proteins from inactivation.     

Zinc regulates the activity of kinase-phosphatase pair (BasPrkC/BasPrpC) in Bacillus anthracis

Bacillus anthracis Ser/Thr protein kinase PrkC (BasPrkC) is important for virulence of the bacterium within the host. Homologs of PrkC and its cognate phosphatase PrpC (BasPrpC) are the most conserved mediators of signaling events in diverse bacteria. BasPrkC homolog in Bacillus subtilis regulates critical processes like spore germination and BasPrpC modulates the activity of BasPrkC by dephosphorylation. So far, biochemical and genetic studies have provided important insights into the roles of BasPrkC and BasPrpC; however, regulation of their activities is not known. We studied the regulation of BasPrkC/BasPrpC pair and observed that Zn²⁺ metal ions can alter their activities. Zn²⁺ promotes BasPrkC kinase activity while inhibits the BasPrpC phosphatase activity. Concentration of Zn²⁺ in growing B. anthracis cells was found to vary with growth phase. Zn²⁺ was found to be lowest in log phase cells while it was highest in spores. This variation in Zn²⁺ concentration is significant for understanding the antagonistic activities of BasPrkC/BasPrpC pair. Our results also show that BasPrkC activity is modulated by temperature changes and kinase inhibitors. Additionally, we identified Elongation Factor Tu (BasEf-Tu) as a substrate of BasPrkC/BasPrpC pair and assessed the impact of their regulation on BasEf-Tu phosphorylation. Based on these results, we propose Zn²⁺ as an important regulator of BasPrkC/BasPrpC mediated phosphorylation cascades. Thus, this study reveals additional means by which BasPrkC can be activated leading to autophosphorylation and substrate phosphorylation.     

Effect of Feeding Millet (Sorghum vulgarie) Protein at Various Protein Levels on Adrenal Lipids of Rats

A significant increase in adrenal weight, total lipids, cholesterol phospholipids and glycerides (mono-and triglycerides) was observed in rats fed millet at 5, 10 and 15 % protein levels respectively for a period of six weeks as compared to rats fed casein at 10 per cent level. Increases in cholesterol were in both its free and esterified fraction. Adrenal phosphatidyl etha-nolamine was increased in all millet fed rats whereas phosphatidyl choline increased in M–15 % and decreased in M–5 % groups. Other phospholipid fractions viz. monophosphatidyl inositol, lysophosphatidyl ethanolamine, sphingomyeline, phosphatidic acid and polyglycerophosphatide also showed significant alterations in rats fed millet protein as compared to control. Incorporation of acetate–l–¹⁴C into adrenal lipids was lower and that of glucose–U–¹⁴C, palmitate–l–¹⁴C and NaH₂³²PO₄ was higher than the control.     

Effect of Feeding Bengal Gram (Cicer arietinum) at Different Protein Levels on Plasma Lipids of Rats

L-Amino acid ligase catalyzes the formation of an α-peptide bond from unprotected L-amino acids in an ATP-dependent manner, and this enzyme is very useful in efficient peptide production. We performed enzyme purification to obtain a novel L-amino acid ligase from Bacillus subtilis NBRC3134, a microorganism producing peptide-antibiotic rhizocticin. Rhizocticins are dipeptide or tripeptide antibiotics and commonly possess L-arginyl-L-2-amino-5-phosphono-3-cis-pentenoic acid. The purification was carried out by detecting L-arginine hydroxamate synthesis activity, and a target enzyme was finally purified 1,280-fold with 0.8% yield. The corresponding gene was then cloned and designated rizA. rizA was 1,242 bp and coded for 413 amino acid residues. Recombinant RizA was prepared, and it was found that the recombinant RizA synthesized dipeptides whose N-terminus was L-arginine in an ATP-dependent manner. RizA had strict substrate specificity toward L-arginine as the N-terminal substrate; on the other hand, the substrate specificity at the C-terminus was relaxed.     

Pathophysiology of white-nose syndrome in bats: a mechanistic model linking wing damage to mortality

White-nose syndrome is devastating North American bat populations but we lack basic information on disease mechanisms. Altered blood physiology owing to epidermal invasion by the fungal pathogen Geomyces destructans (Gd) has been hypothesized as a cause of disrupted torpor patterns of affected hibernating bats, leading to mortality. Here, we present data on blood electrolyte concentration, haematology and acid–base balance of hibernating little brown bats, Myotis lucifugus, following experimental inoculation with Gd. Compared with controls, infected bats showed electrolyte depletion (i.e. lower plasma sodium), changes in haematology (i.e. increased haematocrit and decreased glucose) and disrupted acid–base balance (i.e. lower CO₂ partial pressure and bicarbonate). These findings indicate hypotonic dehydration, hypovolaemia and metabolic acidosis. We propose a mechanistic model linking tissue damage to altered homeostasis and morbidity/mortality.     

Overexpression of WsSGTL1 Gene of Withania somnifera Enhances Salt Tolerance,Heat Tolerance and Cold Acclimation Ability in Transgenic Arabidopsis Plants

Background

Sterol glycosyltrnasferases (SGT) are enzymes that glycosylate sterols which play important role in plant adaptation to stress and are medicinally important in plants like Withania somnifera. The present study aims to find the role of WsSGTL1 which is a sterol glycosyltransferase from W. somnifera, in plant’s adaptation to abiotic stress.

Methodology

The WsSGTL1 gene was transformed in Arabidopsis thaliana through Agrobacterium mediated transformation, using the binary vector pBI121, by floral dip method. The phenotypic and physiological parameters like germination, root length, shoot weight, relative electrolyte conductivity, MDA content, SOD levels, relative electrolyte leakage and chlorophyll measurements were compared between transgenic and wild type Arabidopsis plants under different abiotic stresses - salt, heat and cold. Biochemical analysis was done by HPLC-TLC and radiolabelled enzyme assay. The promoter of the WsSGTL1 gene was cloned by using Genome Walker kit (Clontech, USA) and the 3D structures were predicted by using Discovery Studio Ver. 2.5.

Results

The WsSGTL1 transgenic plants were confirmed to be single copy by Southern and homozygous by segregation analysis. As compared to WT, the transgenic plants showed better germination, salt tolerance, heat and cold tolerance. The level of the transgene WsSGTL1 was elevated in heat, cold and salt stress along with other marker genes such as HSP70, HSP90, RD29, SOS3 and LEA4-5. Biochemical analysis showed the formation of sterol glycosides and increase in enzyme activity. When the promoter of WsSGTL1 gene was cloned from W. somnifera and sequenced, it contained stress responsive elements. Bioinformatics analysis of the 3D structure of the WsSGTL1 protein showed functional similarity with sterol glycosyltransferase AtSGT of A. thaliana.

Conclusions

Transformation of WsSGTL1 gene in A. thaliana conferred abiotic stress tolerance. The promoter of the gene in W.somnifera was found to have stress responsive elements. The 3D structure showed functional similarity with sterol glycosyltransferases.