Acid Extracts Of Liver Research Articles

Histone H1: An Antimicrobial Protein of Atlantic Salmon (Salmo salar)

Antimicrobial activity was detected in acid extracts of liver, intestine, and stomach of healthy Atlantic salmon (Salmo salar). An antimicrobial protein was isolated from salmon liver using acid extraction followed by ammonium sulfate precipitation, large-scale gel filtration chromatography, reverse-phase HPLC, and size exclusion HPLC. The salmon antimicrobial (SAM) protein was found to have a molecular mass of 20,734 Da by MALDI TOF mass spectrometry. Peptide mass fingerprinting and partial sequencing by tandem nanoelectrospray mass spectrometry identified the protein as histone H1. The protein had a minimal inhibitory concentration of 31 μg/mL against E. coli D31 in a plate clearing assay. The effect of the SAM protein on bacterial morphology was indistinguishable from that of (Ala-8,13,18)-magainin II, as shown by scanning electron microscopy, which suggests that the protein disrupts E. coli membranes in a manner similar to that of most antimicrobial peptides. This protein may act as an antimicrobial in vivo through active secretion or by release from cells during infection-related apoptosis.

Discordance of serum and tissue somatomedin levels in growth hormone-stimulated growth in the rat.

Although the somatomedins are believed to mediate GH-induced somatic growth, circulating levels of insulin-like growth factor I (IGF-I) do not always correlate with growth rate. To evaluate a paracrine or autocrine effect that might explain this discordance, the concentrations of plasma and tissue IGF-I were compared with indices of growth in hypophysectomized rats treated with rat GH (rGH). The rats received a total of 250 micrograms rGH by either continuous pump infusion (P) or twice daily injections (I). After 4 days of treatment, the amounts of IGF-I present in acetic acid extracts of liver and kidney and in native serum were determined by RIA and related to proximal tibial epiphyseal plate width. Tibial epiphyseal plate width increased from 198 +/- 6 microns (mean +/- SE) in untreated controls to 339 +/- 13 microns in group P and 347 +/- 9 micron in group I; weight gain was 11.6 +/- 1.0 g in group P and 9.6 +/- 0.8 g in group I, while control animals lost 1.0 g. Serum concentrations of IGF-I were no different between control animals and those in the injection group (0.91 +/- 0.06 vs. 0.90 +/- 0.06 U/ml), whereas levels in the infusion group increased slightly (1.1 +/- 0.05 U/ml). In contrast, rGH administration caused tissue IGF-I to double in liver (control, 0.24 +/- 0.04 U/g; P, 0.51 +/- 0.03 U/g; I, 0.46 +/- 0.05 U/g) and nearly triple in kidney (control, 0.52 +/- 0.05 U/g; P, 1.51 +/- 0.09 U/g; I, 1.36 +/- 0.08 U/g). There was no detectable change in somatomedin-binding protein by gel exclusion chromatography. Since the rGH administered was sufficient to stimulate growth and increase tissue somatomedin levels without corresponding increases in circulating IGF-I, an autocrine or paracrine action of IGF-I appears to mediate GH's initial somatogenic actions in the young rat.