Identification and functional characterization of a novel antistasin/WAP-like serine protease inhibitor from the tropical sea cucumber, Stichopus monotuberculatus

First echinoderm alpha-amylase from a tropical sea cucumber (Holothuria leucospilota): Molecular cloning, tissue distribution, cellular localization and functional production in a heterogenous E.coli system with codon optimization

Holothuria leucospilota (Echinodermata: Holothuroidea) is a widespread tropical sea cucumber with strong value for the ecological restoration of coral reefs. Therefore, some studies regarding the artificial breeding and cultivation of H. leucospilota have been undertaken recently. However, the biological functions of the digestive system of this species have not been elucidated. In this study, a cDNA coding for α-amylase, an indicator of digestive maturity in animals, was identified from H. leucospilota and designated Hl-Amy. The full-length cDNA of the Hl-Amy gene, which is 1734 bp in length with an open reading frame (ORF) of 1578 bp, encodes a 525 amino acid (a.a.) protein with a deduced molecular weight of 59.34 kDa. According to the CaZy database annotation, Hl-Amy belongs to the class of GH-H with the official nomenclature of α-amylase (EC 3.2.1.1) or 4-α-D-glucan glucanohydrolase. The Hl-Amy protein contains a signal peptide at the N-terminal followed by a functional amylase domain, which includes the catalytic activity site. The mRNA expression of Hl-Amy was abundantly exhibited in the intestine, followed by the transverse vessel with a low level, but was hardly detected in other selected tissues. During embryonic and larval development, Hl-Amy was constitutively expressed in all stages, and the highest expression level was observed in the blastula. By in situ hybridization (ISH), positive Hl-Amy signals were observed in different parts of the three different intestinal segments (foregut, midgut and hindgut). The Hl-Amy recombinant protein was generated in an E. coli system with codon optimization, which is necessary for Hl-Amy successfully expressed in this heterogenous system. The Hl-Amy recombinant protein was purified by immobilized metal ion affinity chromatography (IMAC), and its activity of starch hydrolysis was further detected. The optimal temperatures and pH for Hl-Amy recombinant protein were 55°C and 6.0, respectively, with an activity of 62.2 U/mg. In summary, this current study has filled a knowledge gap on the biological function and expression profiles of an essential digestive enzyme in sea cucumber, which may encourage future investigation toward rationalized diets for H. leucospilota in artificial cultivation, and optimized heterogenous prokaryotic systems for producing recombinant enzymes of marine origins.

European Medicinal Leeches-New Roles in Modern Medicine

Before the advent of modern medicine, natural resources were widely used by indigenous populations for the prevention and treatment of diseases. The associated knowledge, collectively described as folk medicine or traditional medicine, was largely based on trial-and-error testing of plant extracts (herbal remedies) and the use of invertebrates, particularly medicinal maggots of the blowfly Lucilia sericata and blood-sucking leeches. The widespread use of traditional medicine in the West declined as scientific advances allowed reproducible testing under controlled conditions and gave rise to the modern fields of biomedical research and pharmacology. However, many drugs are still derived from natural resources, and interest in traditional medicine has been renewed by the ability of researchers to investigate the medical potential of diverse species by high-throughput screening. Likewise, researchers are starting to look again at the benefits of maggot and leech therapy, based on the hypothesis that the use of such animals in traditional medicine is likely to reflect the presence of specific bioactive molecules that can be developed as drug leads. In this review, we consider the modern medical benefits of European medicinal leeches based on the systematic screening of their salivary proteins.