Molecular cloning of a hyaluronidase from Bothrops pauloensis venom gland

Comparative transcriptome analysis of sensory genes from the antenna and abdomen of Quadrastichus mendeli Kim

Quadrastichus mendeli Kim is one of the most important parasitoids of Leptocybe invasa Fisher et La Salle, which is an invasive gall-making pest in eucalyptus plantations in the world. Gall-inducing insects live within plant tissues and induce tumor-like growths that provide the insects with food, shelter, and protection from natural enemies. Empirical evidences showed that sensory genes play a key role in the host location of parasitoids. So far, what kind of sensory genes regulate parasitoids to locate gall-inducing insects has not been uncovered. In this study, sensory genes in the antenna and abdomen of Q. mendeli were studied using high-throughput sequencing. In total, 181,543 contigs was obtained from the antenna and abdomen transcriptome of Q. mendeli. The major sensory genes (chemosensory proteins, CSPs; gustatory receptors, GRs; ionotropic receptors, IRs; odorant binding proteins, OBPs; odorant receptors, ORs; and sensory neuron membrane proteins, SNMPs) were identified, and phylogenetic analyses were performed with these genes from Q. mendeli and other model insect species. The gene co-expression network constructed by WGCNA method is robust and reliable. There were 10,314 differentially expressed genes (DEGs), and among them, 99 genes were DEGs. A comprehensive sequence resource with desirable quality was built by comparative transcriptome of the antenna and abdomen of Q. mendeli, enriching the genomic platform of Q. mendeli.

Enzymatic Production of Low-Molecular-Weight Hyaluronan and Its Oligosaccharides: A Review and Prospects

Hyaluronic acid (HA) is a nonsulfated linear glycosaminoglycan with a negative charge. Different from the high-molecular-weight HAs, the low-molecular-weight HAs (LMW-HAs, 4-120 kDa) and hyaluronan oligosaccharides (O-HAs, <4 kDa) exhibit certain unique biological properties, owing to which these have a wide range of applications in the field of medicine. However, the chemical synthesis of high-purity LMW-HAs and O-HAs requires complex procedures, which renders this process difficult to achieve. The degradation of HA is achieved under the catalysis of hyaluronidases. In recent years, various hyaluronidase genes have been identified, and their enzymatic properties have been analyzed. In this context, the present review summarizes the hyaluronidases from different sources, which have been characterized. The review focuses on the crystal structure and the catalytic mechanism underlying the biological properties of hyaluronidases. In addition, the molecular weight distributions and the preparation approaches of the enzymatic products LMW-HAs and O-HAs are described. The general orientation of the research on hyaluronidases was speculated based on the existing literature. Accordingly, the efficient large-scale production of LMW-HAs and O-HAs using the green enzymatic approach was anticipated.

Phytochemical composition, antisnake venom and antibacterial activities of ethanolic extract of Aegiphila integrifolia (Jacq) Moldenke leaves

Snakebites are considered a major neglected tropical disease, resulting in around 100,000 deaths per year. The recommended treatment by the WHO is serotherapy, which has limited effectiveness against the toxins involved in local tissue damage. In some countries, patients use plants from folk medicines as antivenoms. Aegiphila species are common plants from the Brazilian Amazon and are used to treat snakebites. In this study, leaves from Aegiphila integrifolia (Jacq) Moldenke were collected from Roraima state, Brazil and its ethanolic extract was evaluated through in vitro and in vivo experiments to verify their antiophidic activity against Bothrops atrox crude venom. The isolated compounds from A. integrifolia were analyzed and the chemical structures were elucidated on the basis of infrared, ultraviolet, mass, ¹H and ¹³C NMR spectrometry data. Among the described compounds, lupeol (7), betulinic acid (1), β-sitosterol (6), stigmasterol (5), mannitol (4), and the flavonoids, pectolinarigenin (2) and hispidulin (3), were identified. The ethanolic extract and flavonoids (2 and 3) partially inhibited the proteolytic, phospholipase A2 and hyaluronidase activities of B. atrox venom, and the skin hemorrhage induced by this venom in mice. Antimicrobial activity against different bacteria was evaluated and the extract partially inhibited bacterial growth. Thus, taken together, A. integrifolia ethanolic extract has promising use as an antiophidic and antimicrobial.

Biochemical and molecular characterization of the hyaluronidase from Bothrops atrox Peruvian snake venom

Snake venoms are a rich source of enzymes such as metalloproteinases, serine proteinases phospholipases A2 and myotoxins, that have been well characterized structurally and functionally. However, hyaluronidases (E.C.3.2.1.35) have not been studied extensively. In this study, we describe the biochemical and molecular features of a hyaluronidase (Hyal-Ba) isolated from the venom of the Peruvian snake Bothrops atrox. Hyal-Ba was purified by a combination of ion-exchange and gel filtration chromatography. Purified Hyal-Ba is a 69-kDa (SDS-PAGE) monomeric glycoprotein with an N-terminal amino acid sequence sharing high identity with homologous snake venom hyaluronidases. Detected associated carbohydrates were hexoses (16.38%), hexosamines (2.7%) and sialic acid (0.69%). Hyal-Ba selectively hydrolyzed only hyaluronic acid (HA; specific activity = 437.5 U/mg) but it did not hydrolyze chondroitin sulfate or heparin. The optimal pH and temperature for maximum activity were 6.0 and 40 °C, respectively, and its Km was 0.31 μM. Its activity was inhibited by EDTA, iodoacetate, 2-mercaptoethanol, TLCK and dexamethasone. Na⁺ and K⁺ (0.2 M) positively affect hyaluronidase activity; while Mg²⁺, Br²⁺, Ba²⁺, Cu²⁺, Zn²⁺, and Cd²⁺ reduced catalytic activity. Hyal-Ba potentiates the hemorrhagic and hemolytic activity of whole venom, but decreased subplantar edema caused by an l-amino acid oxidase (LAAO). The Hyal-Ba cDNA sequence (2020 bp) encodes 449 amino acid residues, including the catalytic site residues (Glu135, Asp133, Tyr206, Tyr253 and Trp328) and three functional motifs for N-linked glycosylation, which are conserved with other snake hyaluronidases. Spatial modeling of Hyal-Ba displayed a TIM-Barrel (α/β) fold and an EGF-like domain in the C-terminal portion. The phylogenetic analysis of Hyal-Ba with other homologous Hyals showed the monophyly of viperids. Further, Hyal-Ba studies may extend our knowledge of B. atrox toxinology and provides insight to improve the neutralizing strategies of therapeutic antivenoms.

In-Depth Venome of the Brazilian Rattlesnake Crotalus durissus terrificus: An Integrative Approach Combining Its Venom Gland Transcriptome and Venom Proteome

Snake venoms are complex mixtures mainly composed of proteins and small peptides. Crotoxin is one of the most studied components from Crotalus venoms, but many other components are less known due to their low abundance. The venome of Crotalus durissus terrificus, the most lethal Brazilian snake, was investigated by combining its venom gland transcriptome and proteome to create a holistic database of venom compounds unraveling novel toxins. We constructed a cDNA library from C. d. terrificus venom gland using the Illumina platform and investigated its venom proteome through high resolution liquid chromotography-tandem mass spectrometry. After integrating data from both data sets, more than 30 venom components classes were identified by the transcriptomic analysis and 15 of them were detected in the venom proteome. However, few of them (PLA₂, SVMP, SVSP, and VEGF) were relatively abundant. Furthermore, only seven expressed transcripts contributed to ∼82% and ∼73% of the abundance in the transcriptome and proteome, respectively. Additionally, novel venom proteins are reported, and we highlight the importance of using different databases to perform the data integration and discuss the structure of the venom components-related transcripts identified. Concluding, this research paves the way for novel investigations and discovery of future pharmacological agents or targets in the antivenom therapy.

Agkihpin, a Distinct SVTLE from the Venom of Gloydius halys Pallas: Purification, Characterization and Structure-Activity Determination

Blood clots produced by snake-venom thrombin-like enzymes (SVTLEs) are cleared rapidly, which makes SVTLEs attractive as potential candidates for antithrombotic therapy. We isolated a SVTLE, agkihpin, from the venom of Gloydius halys Pallas. Agkihpin was confirmed to a single-chain TLE with molecular mass of 25.5 kD, pI of 7.43, optimal pH of 8.0 (hydrolyzing TAME), linked carbohydrate absent, and weak fibrinogen clotting activity. It was also found that (i) G. halys might be the latest species in SVTLEs phylogenetic tree; (ii) different level of conservation was shown among the SVTLEs from the Viperidae snakes. Some of those site may account for different activities exhibited by those SVTLEs, especially position 181, at which a fibrinogenolytic activity increase was found when a basic and larger amino acid substituted by a neutral and smaller one; (iii) an extra α-helix constructed with a 'Pro + acidic amino acid + aromatic amino acid' pattern was found in the SVTLEs from Gloydius and Agkistrodon snakes, although it does not necessarily imply an effect on the fibrinogenolytic activity of the SVTLEs. This study provided some new insight into the activity of SVTLE.