Abstract: The present invention relates to a nucleus covered or coated with a film including one or more PHA. The invention also relates to a PHA, characterized in that it is of the type PHB-V, a film and a composition including the PHA. The invention further relates to a film or a composition including a PHA and zosteric acid or a bioactive molecule. The invention moreover relates to a surface, preferably a nucleus, covered with the film of PHA, a method for production thereof, and methods for grafting a pearl oyster and producing a pearl using this nucleus. Finally, the present invention relates to a method for reducing graft failure and/or for improving the quality of the pearl using the nucleus according to the invention.

Abstract: A nucleus coated with a film includes one or more exopolysaccharides (EPS) and optionally one or more bioactive molecules such as bactericidal or bacteriostatic agents, cicatrizing agents and/or anti-inflammatory agents. A method for obtaining the nucleus, in order to inhibit graft rejection in pearl oysters is also described.

Abstract: The present invention relates to the use of transcripts of genes encoding antimicrobial peptides, for evaluating the resistance of penaeid shrimp, in particular of the species Litopenaeus stylirostris, to bacterial infections, in particular to vibriosis.

Abstract: The invention concerns antimicrobial peptides obtained from penaeid prawns having the following characteristics: a molecular mass of about 5 to 7 kDa; a pHi not less than 9; an N-terminal portion comprising a region (A) of about 15 to 25 amino acids rich in proline; and a C-terminal portion comprising a region (B) of about 20 to 30 amino acids and containing 6 cysteine residues forming three intramolecular disulfide bonds. The invention also concerns the nucleic acid sequences coding for said peptides and enabling their production by genetic engineering.