James M. Carlberg

Discovery and Characterization of Two Isoforms of Moronecidin, a Novel Antimicrobial Peptide from Hybrid Striped Bass

We isolated a novel 22-residue, C-terminally amidated antimicrobial peptide, moronecidin, from the skin and gill of hybrid striped bass. Two isoforms, differing by only one amino acid, are derived from each parental species, white bass (Morone chrysops) and striped bass (Morone saxatilis). Molecular masses (2543 and 2571 Da), amino acid sequences (FFHHIFRGIVHVGKTIH(K/R)LVTGT), cDNA, and genomic DNA sequences were determined for each isoform. A predicted 79-residue moronecidin prepropeptide consists of three domains: a signal peptide (22 amino acids), a mature peptide (22 amino acids), and a C-terminal prodomain (35 amino acids). The synthetic, amidated white bass moronecidin exhibited broad spectrum antimicrobial activity that was retained at high salt concentration. An α-helical structure was confirmed by circular dichroism spectroscopy. The moronecidin gene consists of three introns and four exons. Peptide sequence and gene organization were similar to pleurocidin, an antimicrobial peptide from winter flounder. A TATA box and several consensus-binding motifs for transcription factors were found in the region 5′ to the transcriptional start site. Moronecidin gene expression was detected in gill, skin, intestine, spleen, anterior kidney, and blood cells by kinetic reverse transcription (RT)-PCR. Thus, moronecidin is a new α-helical, broad spectrum antimicrobial peptide isolated from the skin and gills of hybrid striped bass.

Effects of chelae immobilization on growth and survivorship for individually and communally raised lobsters, Homarus americanus

Abstract Communal rearing systems for juvenile American lobsters, Homarus americanus , allow lower production costs than are possible in individual rearing systems, but often result in high levels of mortality due to behavioral interactions such as cannibalism. This study evaluated the effects on growth and survivorship of two methods of bilateral immobilization of chelae (chelae and dactylopodite removal) for stage IV juvenile lobsters treated initially and at monthly intervals for 6 months. Replicate groups of lobsters were cultured in communal tanks and individual holding containers. After 6 months in individual containers, mortality was highest in the lobsters in which the chelae were completely removed. Lobsters cultured individually and subjected to dactylopodite removal exhibited less mortality. Howerer, this pattern was reversed in the mass rearing system. Cannibalism appeared to be the major source of mortality for lobsters in the mass rearing control group, whereas mortality in lobsters from which the chelae had been removed was due primarily to treatment stress and non-community based factors. Growth was not affected by immobilization of the chelae. Within the mass rearing system, growth rates for the lobsters from the two treatment groups was suppressed after the fourth month when their size and increased survivorship produced a situation where the effective bottom area per animal was smaller than that required for unlimited growth. This reduction in mortality with insignificant effect on growth required relatively little investment in man-hours; chelae removal required less than 2 min of effort for each surviving lobster. By using the chelae removal technique on communally raised juvenile lobsters, major equipment and maintenance costs inherent to individual rearing systems probably could be avoided with little or no impairment of growth.