A serine protease-associated lectin in the cytolytic system of blowfly (Chrysomya megacephala) larvae: Evidence and characterization.

Cytolytic activity against invading microorganisms is one of the innate forms of immunity in invertebrates. A serine protease-associated sialic acid-specific cytolytic lectin was purified using glutaraldehyde-fixed ox erythrocytes from the larval extract of blowfly (Chrysomya megacephala). The purified lectin lysed vertebrate erythrocytes with effective haemolysis of ox red blood cells (RBCs) in an isotonic medium. The degree of haemolytic (HL) activity of the purified cytolytic lectin depended on its concentration, pH, temperature, and calcium ions. It was sensitive to ethylenediaminetetraacetic acid. The native molecular mass of the C-type lectin was 260 ± 26 kDa, comprising four different polypeptide subunits of 75 kDa (pI ~8), 69 kDa (pI ~7.0), 61 kDa (pI ~5.3), and 55 kDa (pI ~4.6). The association between the C-type lectin and serine protease was confirmed by MALDI-TOF-MS analysis that revealed its homology in the same spectral peak as well as the proteases and phenylmethylsulphonyl fluoride inhibition of HL activity. Haemolysis inhibition by N-acetylneuraminic acid and other sugars revealed the properties of the lectin. The purified lectin distorted the integrity of ox RBCs and Paenalcaligenes hermetiae. This in vitro study documents the presence of a cytolytic system in blowfly (C. megacephala) larvae for the clearance of invading microbial pathogens in their feeding niche.

ß-Galactoside binding lectin from caddisfly larvae, Stenopsyche kodaikanalensis with selective modes of antibacterial activity: Purification and characterization.

Insects sustain the invading bacterial pathogens by inducing the production of lectin which participates in surveillance of non-self molecules. The antibacterial property of lectin is an inevitable aspect of innate immune system especially for the insects feeding the detritus organic matter. ß-galactoside binding lectin possessing antibacterial property was detected and purified from the hemolymph of larvae of caddisfly, Stenopsyche kodaikanalensis using affinity chromatography. The purified lectin exhibited highest hemagglutination titer value against buffalo erythrocytes and has affinity to lactose and fetuin which contains ß-galactoside linkages. It was found to be calcium independent, EDTA insensitive and heat labile. These reveal the characteristics features of S-Lac lectin. The molecular weight of lectin was 360 kDa with five distinct subunits such as 95, 90, 66, 62 and 47 kDa. The sequences acquired through MALDI-TOF-MS analysis shared homologies to the putative conserved region of leguminous lectin. Antibacterial studies were carried out with native soil bacterial isolates. It revealed that the lectin possessed the specific modes of action against bacteria that it can agglutinate the Bacillus subtilis and lyse the Bacillus flexus.

Population genetic structure and molecular diversity of Leucinodes orbonalis based on mitochondrial COI gene sequences.

Leucinodes orbonalis is a destructive pest found throughout eggplant cultivating fields of Tamil Nadu, India. The genetic diversity and its population structure were investigated in this pest using mitochondrial cytochrome c oxidase subunit I (COI) gene sequences from 20 populations of L. orbonalis collected from various agro-climatic conditions. The study indicated almost no genetic diversity among various populations. The COI nucleotide sequence based haplotype analysis also revealed no significant genetic variation among various populations. However, haplotype network analysis with three clades was nearly matching with the structure of phylogenetic analysis that showed geographical separations induced distribution of some genetic variation. The PCA and nMDS Shephard's plot analyses were also illustrated that the populations sampled were nearly matched with phylogenetic tree and haplotype network. This study on phylogeographical structure using the mitochondrial COI sequence diversity of L. orbonalis therefore suggested presence of few genetically distinct populations due to some specific habitat requirements.

Purification and functional characterization of lectin with phenoloxidase activity from the hemolymph of cockroach, Periplaneta americana.

Lectins also identified as hemagglutinins are multivalent proteins and on account of their fine sugar-binding specificity play an important role in immune system of invertebrates. The present study was carried out on the hemolymph lectin of cockroach, Periplaneta americana with appropriate screening and purification to understand its molecular as well as functional nature. The lectin from the hemolymph was purified using ion-exchange chromatography. The approximate molecular weight of purified lectin was 340 kDa as determined by FPLC analysis. Rabbit erythrocytes were highly agglutinated with purified lectin from the hemolymph of P. americana. The hemagglutination activity (HA) of lectin was specifically inhibited by fucose. Glycoproteins also inhibited the HA activity of lectin. The amino acid sequences of the purified lectin revealed homology with amino acid sequences of allergen proteins from P. americana. Purified lectin showed the highest phenoloxidase activity against dopamine. The activators such as exogenous proteases and LPS from Escherichia coli and Salmonella minnesota significantly enhanced the PO activity of the purified lectin. Besides, the presence of copper and hemocyanin conserved domain in the purified lectin provided a new facet that insects belonging to the ancient clade such as cockroaches retained some traces of evolutionary resemblance in possessing lectin of ancient origin.