Digital library

The common sea hare Aplysia kurodai is known to be a good source for the enzymes degrading seaweed polysaccharides. Recently four cellulases, i.e., 95, 66, 45, and 21 kDa enzymes, were isolated from A. kurodai (Tsuji et al., 2013). The former three cellulases were regarded as glycosyl-hydrolase-family 9 (GHF9) enzymes, while the 21 kDa cellulase was suggested to be a GHF45 enzyme. The 21 kDa cellulase was significantly heat stable, and appeared to be advantageous in performing heterogeneous expression and protein-engineering study. In the present study, we determined some enzymatic properties of the 21 kDa cellulase and cloned its cDNA to provide the basis for the protein engineering study of this cellulase. The purified 21 kDa enzyme, termed AkEG21 in the present study, hydrolyzed carboxymethyl cellulose with an optimal pH and temperature at 4.5 and 40°C, respectively. AkEG21 was considerably heat-stable, i.e., it was not inactivated by the incubation at 55°C for 30 min. AkEG21 degraded phosphoric-acid-swollen cellulose producing cellotriose and cellobiose as major end products but hardly degraded oligosaccharides smaller than tetrasaccharide. This indicated that AkEG21 is an endolytic β-1,4-glucanase (EC 3.2.1.4). A cDNA of 1013 bp encoding AkEG21 was amplified by PCR and the amino-acid sequence of 197 residues was deduced. The sequence comprised the initiation Met, the putative signal peptide of 16 residues for secretion and the catalytic domain of 180 residues, which lined from the N-terminus in this order. The sequence of the catalytic domain showed 47–62% amino-acid identities to those of GHF45 cellulases reported in other mollusks. Both the catalytic residues and the N-glycosylation residues known in other GHF45 cellulases were conserved in AkEG21. Phylogenetic analysis for the amino-acid sequences suggested the close relation between AkEG21 and fungal GHF45 cellulases.

Coastal ocean ecosystems have always served human populations—they provide food security, livelihoods, coastal protection, and defense. Ocean acidification is a global threat to these ecosystem services, particularly when other local and regional stressors combine with it to jeopardize coastal health. Monitoring efforts call for a coordinated global approach toward sustained, integrated coastal ocean health observing networks to address the region-specific mix of factors while also adhering to global ocean acidification observing network principles to facilitate comparison among regions for increased utility and understanding. Here, we generalize guidelines for scoping and designing regional coastal ocean acidification observing networks and provide examples of existing efforts. While challenging in the early stages of coordinating the design and prioritizing the implementation of these observing networks, it is essential to actively engage all of the relevant stakeholder groups from the outset, including private industries, public agencies, regulatory bodies, decision makers, and the general public. The long-term sustainability of these critical observing networks will rely on leveraging of resources and the strength of partnerships across the consortium of stakeholders and those implementing coastal ocean health observing networks

Considerable work has been done on the chemical aspects of Indian seaweeds during the last three decades, of which those up to 1970 have been reviewed by Umamaheswara Rao (1970). In this chapter the information so far collected on the mineral constituents, carbohydrates and other chemicals is presented.