Biomedical subjects

Julien de Lorgeril

Publications and source records attributed to Julien de Lorgeril.

4 recordsLinked to original sources

PubMed2006

PenBase, the shrimp antimicrobial peptide penaeidin database: sequence-based classification and recommended nomenclature.

Antimicrobial peptides play a major role in innate immunity. The penaeidins, initially characterized from the shrimp Litopenaeus vannamei, are a family of antimicrobial peptides that appear to be expressed in all penaeid shrimps. As of recent, a large number of penaeid nucleotide sequences have been identified from a variety of penaeid shrimp species and these sequences currently reside in several databases under unique identifiers with no nomenclatural continuity. To facilitate research in this field and avoid potential confusion due to a diverse number of nomenclatural designations, we have made a systematic effort to collect, analyse, and classify all the penaeidin sequences available in every database. We have identified a common penaeidin signature and subsequently established a classification based on amino acid sequences. In order to clarify the naming process, we have introduced a 'penaeidin nomenclature' that can be applied to all extant and future penaeidins. A specialized database, PenBase, which is freely available at , has been developed for the penaeidin family of antimicrobial peptides, to provide comprehensive information about their properties, diversity and nomenclature.

Amino Acid Sequence↗

PubMed2005

Molecular characterization of penaeidins from two Atlantic Brazilian shrimp species, Farfantepenaeus paulensis and Litopenaeus schmitti.

We report here the molecular cloning of new members of the penaeidin family from two Atlantic penaeids from Brazil, Litopenaeus schmitti and Farfantepenaeus paulensis. The presence of penaeidins in the granular hemocytes of both shrimps was first evidenced by immunofluorescence, using polyclonal antibodies raised against L. vannamei penaeidin Litvan PEN3-1. cDNAs from the hemocytes of both Brazilian species were obtained by reverse transcription and the sequences encoding penaeidins were amplified by PCR, using primers based on penaeidin consensus sequences. Five penaeidin clones were obtained. According to the international penaeidin classification (PenBase, http://www.penbase.immunaqua.com), the deduced amino acid sequences of two clones from L. schmitti and two from F. paulensis belong to the PEN2 subgroup and one clone from L. schmitti to the PEN4 subgroup of penaeidins. Surprisingly, no penaeidin from the PEN3 subgroup was obtained in both shrimp species, even though this subgroup appears to be the most commonly expressed in the hemocytes of penaeids.

Amino Acid Sequence↗

PubMed2005

Identification of genes that are differentially expressed in hemocytes of the Pacific blue shrimp (Litopenaeus stylirostris) surviving an infection with Vibrio penaeicida.

Considerable progress has been made in the field of invertebrate immunity through the characterization of genes involved in the response to infection and/or stress. However, the mechanisms by which commercially important marine invertebrates can successfully survive an infection remain largely unknown. For the first time in an invertebrate model, we have searched to discover genes involved in the survival capacity of shrimp using the highly pathogenic bacteria, Vibrio penaeicida. In the present study, we applied the technique of suppression subtractive hybridization (SSH) to hemocyte cDNAs from infected and uninfected shrimp, only using samples from individuals that had survived 96 h postinfection. The resulting library contains 260 expressed sequence tagged (EST) cDNA clones potentially representing highly expressed genes in surviving shrimp. Sequence similarity comparisons were made, and putative identities were assigned to clones that were at least 51% identical to known genes. This analysis showed two functional categories that were highly represented: those of genes involved in immune reactions (10.7% of the ESTs) and those involved in proliferation-hematopoiesis (10.3%). Expression pattern profile analyses of selected ESTs at different times postinfection confirmed the differential expression of the genes and efficiency of the SSH method. Differences in gene transcript abundance, for select ESTs encoding antimicrobial effectors, were evidenced by real-time PCR between shrimp that survived acute Vibrio infection and those individuals that did not survive acute Vibrio infection. These results suggest there are basic differences at the level of transcript abundance for genes directly involved in immune and hematopoietic processes from shrimp that survive and do not survive infection.

Animals↗

PubMed2004

Insights into the anti-microbial defense of marine invertebrates: the penaeid shrimps and the oyster Crassostrea gigas.

Research on innate immunity of the penaeid shrimps and the oyster Crassostrea gigas is motivated greatly by economical necessities. Indeed, the aquaculture of these organisms is now limited by the development of infectious diseases. Studying anti-microbial peptides/proteins (AMPs), which are effector molecules of the host defense, is particularly attractive not only for progressing basic knowledge on immunity but also because they offer various possible applications for disease management in aquaculture. AMPs are explored with a global approach,considering their structure, properties, function, gene expression, and tissue distribution during the response to infections. In shrimp, investigations of the penaeidins, which are constitutively expressed peptides, have highlighted the importance of hemocytes and hematopoiesis as major elements of the immune response, providing both local and systemic reactions. The activation of hematopoiesis must be regarded as a regulatory way for the expression and distribution of constitutively expressed immune effectors. As complementary approaches, genomics and gene profiling are promising to deepen our understanding of the anti-microbial defense of the oyster and the shrimp. However, real progress will depend also on the characterization of hemocyte lineages and hematopoiesis of these marine invertebrates as well as on the ontogenesis of their immune systems.

Animals↗