Conserved water-mediated H-bonding dynamics of catalytic Asn 175 in plant thiol protease

The role of invariant water molecules in the activity of plant cysteine protease is ubiquitous in nature. On analysing the 11 different Protein DataBank (PDB) structures of plant thiol proteases, the two invariant water molecules W1 and W2 (W220 and W222 in the template 1PPN structure) were observed to form H-bonds with the O_b atom of Asn 175. Extensive energy minimization and molecular dynamics simulation studies up to 2 ns on all the PDB and solvated structures clearly revealed the involvement of the H-bonding association of the two water molecules in fixing the orientation of the asparagine residue of the catalytic triad. From this study, it is suggested that H-bonding of the water molecule at the W1 invariant site better stabilizes the Asn residue at the active site of the catalytic triad.     

Biochemical Conservation and Evolution of Germacrene A Oxidase in Asteraceae

Sesquiterpene lactones are characteristic natural products in Asteraceae, which constitutes ∼8% of all plant species. Despite their physiological and pharmaceutical importance, the biochemistry and evolution of sesquiterpene lactones remain unexplored. Here we show that germacrene A oxidase (GAO), evolutionarily conserved in all major subfamilies of Asteraceae, catalyzes three consecutive oxidations of germacrene A to yield germacrene A acid. Furthermore, it is also capable of oxidizing non-natural substrate amorphadiene. Co-expression of lettuce GAO with germacrene synthase in engineered yeast synthesized aberrant products, costic acids and ilicic acid, in an acidic condition. However, cultivation in a neutral condition allowed the de novo synthesis of a single novel compound that was identified as germacrene A acid by gas and liquid chromatography and NMR analyses. To trace the evolutionary lineage of GAO in Asteraceae, homologous genes were further isolated from the representative species of three major subfamilies of Asteraceae (sunflower, chicory, and costus from Asteroideae, Cichorioideae, and Carduoideae, respectively) and also from the phylogenetically basal species, Barnadesia spinosa, from Barnadesioideae. The recombinant GAOs from these genes clearly showed germacrene A oxidase activities, suggesting that GAO activity is widely conserved in Asteraceae including the basal lineage. All GAOs could catalyze the three-step oxidation of non-natural substrate amorphadiene to artemisinic acid, whereas amorphadiene oxidase diverged from GAO displayed negligible activity for germacrene A oxidation. The observed amorphadiene oxidase activity in GAOs suggests that the catalytic plasticity is embedded in ancestral GAO enzymes that may contribute to the chemical and catalytic diversity in nature.     

Biochemical and immunological characterization of the cloned crystal toxin of Bacillus thuringiensis var. israelensis

The protein components of the cloned crystal toxin of Bacillus thuringiensis var. israelensis were separated by polyacrylamide gel electrophoresis under denaturing conditions. Using an antiserum to the solubilized B. thuringiensis var. israelensis crystal protein as a probe, immunological homology between the crystal protein components of B. thuringiensis var. israelensis and those of the recombinant B. megaterium strain VB131 was tested. The results from this study indicate that the crystal inclusion of the recombinant strain contains only the 130 kilodalton protein and not the 68 or the 28 kilodalton proteins of the crystal toxin of B. thuringiensis var. israelensis and that the 130 kilodalton protein is primarily responsible for the mosquitocidal activity of this organism.     

Influence of a carbamate pesticide on growth,respiration (14C)-carbon metabolism and symbiosis of aRhizobium sp.

Summary Addition of aldicarb (2 methyl-2(methyl thio) propionaldehyde-0-methyl carbamoyl oxime) in the growth medium enhanced the growth ofRhizobium sp. (cowpea group) at 2 ppm level while an inhibition was observed at the normal (5 ppm) and higher (10 ppm) concentrations. Respiration of the cells was also inhibited by 5 and 10 ppm levels of the chemical eventhough a stimulation was observed at 2 ppm (lower) concentration. The insecticide, when incorporated at 5 and 10 ppm levels in the medium increased the¹⁴C-glucose incorporation and considerably altered the assimilation of the radioactive carbon in different fractions of rhizobium cells. Soil application of this insecticide (Temik 10 G) reduced the number of nodules formed and the total nitrogen content in cowpea plants inoculated with theRhizobium sp. but enhanced the dry matter production of cowpea plants.Based on the M. Sc. thesis submitted by the first author to the Tamil Nadu Agricultural University, Coimbatore-3.     

Phenothiazine–rhodamine‐based colorimetric and fluorogenic ‘turn‐on' sensor for Zn2+ and bioimaging studies in live cells

A phenothiazine–rhodamine (PTRH) fluorescent dyad was synthesized and its ability to selectively sense Zn²⁺ ions in solution and in in vitro cell lines was tested using various techniques. When compared with other competing metal ions, the PTRH probe showed the high selectivity for Zn²⁺ ions that was supported by electronic and emission spectral analyses. The emission band at 528 nm for the PTRH probe indicated the ring closed form of PTRH, as for Zn²⁺ ion binding to PTRH, the λ_em get shift to 608 nm was accompanied by a pale yellow to pink colour (under visible light) and green to pinkish red fluorescence emission (under UV light) due to ring opening of the spirolactam moiety in the PTRH ligand. Spectral overlap of the donor emission band and the absorption band of the ring opened form of the acceptor moiety contributed towards the fluorescence resonance energy transfer ON mechanism for Zn²⁺ ion detection. The PTRH sensor had the lowest detection limit for Zn²⁺, found to be 2.89 × 10^?8 M. The sensor also demonstrated good sensing application with minimum toxicity for in vitro analyses using HeLa cells.     

Length-weight relationship of six demersal fish species from Gulf of Mannar,Bay of Bengal,Eastern Indian Ocean

Length-weight relationship (LWR) parameters were analysed for six demersal finfish species from the Gulf of Mannar coast, Bay of Bengal. Fishes were sampled monthly from the landings of trawlers operated along the coast of Tuticorin and Rameshwaram with a cod-end mesh size of 35 mm at the depth of 60–80 m. Fish specimens were sampled by measuring the total length (TL) and total weight (TW) with precision to 0.1 cm and 0.1 g respectively. The present study also recorded a new maximum total length for Engyprosopon macrolepis, Torquigener brevipinnis and Leiognathus brevirostris.     

Ensuring the adaptive potential of Coastal wetlands of India- the need of the hour for sustainable management

India is endowed with a variety of coastal wetlands viz., mangroves, seagrasses, saltmarshes, coral reefs, lagoons and tidal flats, and the country is also a signatory to the Ramsar Convention on Wetlands and the Convention of Biological Diversity, besides having a robust framework of laws and policies, governing the wetland conservation. However, the conservation strategies can better be improved in the context of increasing pressures and threats and limited success of restoration/rehabilitation. Land conversion and ecological degradation of coastal wetlands are the stressors, associated with rapid coastal developmental activities and climate change. The coastal wetlands require desired habitat niche and hence, the conversion of coastal wetlands to other land uses (including agricultural and urban lands) may lead to permanent loss, whereas ecologically degraded coastal wetlands may be resilient if supported by effective protection measures. Preventing the habitat conversion and maximizing the adaptive potential (viz., the ability of populations or species to adapt to rapid environmental change with minimal disruption) by preserving the ecological health are the need of the hour to safeguard the existing coastal wetlands and sustain the provisional ecosystem services offered by them rather than short-term increase in area by unproductive restoration/rehabilitation efforts. Since coastal wetlands are flow through ecosystems, preserving the hydrological connectivity, facilitating the connectivity between adjacent ecosystems and protection of natural corridors are potential strategies that are required to enhance the adaptive potential of coastal wetlands. This analysis calls for site-specific, long-term and integrated ecosystem-based protection, management and rehabilitation strategies based on scientific principles and enforcing the effective legislative measures to regularize the coastal developmental activities in India.

     

Dietary Administration of Probiotic Aeromonas veronii V03 on the Modulation of Innate Immunity,Expression of Immune-Related Genes and Disease Resistance Against Aeromonas hydrophila Infection in Common Carp (Cyprinus carpio)

This study investigates the effects of dietary Aeromonas veronii V03 supplementation on growth performances, innate immunity, and expression of immune-related genes in lymphoid organs of Cyprinus carpio and resistance to Aeromonas hydrophila infection. Fish were fed for 4 weeks with basal diet (BD; without probiotic), and experiment diet containing different doses of A. veronii V03 at 3.2 × 10⁷ (DI) and 3.5 × 10⁹ (DII) CFU g⁻¹ of diet. At the end of the probiotic feeding trial, fish were challenged with A. hydrophila, and the percentage of survival rates was recorded over 7 days. Results revealed that fish fed with A. veronii V03 demonstrated a significant improvement in growth and enhancement of innate immunity, including respiratory burst, myeloperoxidase, and lysozyme activities, and total immunoglobulin level compared with BD fed to fish. Relatively, expression of cytokines (MyD88, IL-1β1, IL-8, and IL-10) and c- and g-type lysozymes were significantly up- and downregulated in lymphoid organs of fish. Moreover, dietary supplementation of A. veronii V03 exhibited significantly (p < 0.001) higher survival rates of DI (90%) and DII (96.66%) compared with BD (53.33%) fed fish against A. hydrophila infection. These findings help to understand the effects of probiotic A. veronii V03 administrated feed influences on growth and ailment resistance to A. hydrophila infection by regulating innate and systemic immunity in common carp fish.

     

Could Dermaseptin Analogue be a Competitive Inhibitor for ACE2 Towards Binding with Viral Spike Protein Causing COVID19?: Computational Investigation

International Journal of Peptide Research and Therapeutics - Initial phase of COVID-19 infection is associated with the binding of viral spike protein S1 receptor binding domain (RBD) with the host...