Spectroscopic investigations of peptide 401 from bee venom

The circular dichroism (CD) and ¹H-nmr properties of peptide 401, a bee venom component with 22 amino acid residues and two disulfide bridges, have been studied under a variety of conditions and compared with those of the structurally related octadecapeptide apamin. The major component of the relatively intense CD signal in the 200–230-nm region in both cases probably arises from the rigid asymmetric ring structures of the disulfide bridges. CD spectra are practically unaffected by pH (in the region 1–7), solvent (water, trifluoroethanol, dioxane/water mixtures), concentration of peptide, or additions of salt (guanidinium chloride, KCl). Temperature changes (in the range 20–59°C) have only a modest influence. For both apamin and peptide 401, reduction of the two disulfide bridges results in a dramatic change of the CD spectrum, which acquires the characteristic form of a random coil. Preliminary ¹H-nmr data are presented for both the reduced and the oxidized form. Several resonance peaks could be assigned on the basis of the theoretical random-coil spectrum. In the oxidized forms, six slowly exchangeable amide protons could be found in a spectrum taken at low pH, which are ascribed to intramolecular hydrogen bonds. Each of the four protons of the two histidine residues of peptide 401 appears as two distinct resonance peaks in the oxidized form but not in the reduced form. This is interpreted as arising from conformational heterogeneity of peptide 401.     

Ichthyoplankton entrainment

A 12-month study was carried out to quantify the numbers of fish eggs and larvae taken into Fawley Power Station on Southampton Water. Fourteen species of fish and the eggs of four species were identified. Estimates are given of the total annual entrainment in immediate numbers and adult equivalents. Findings of previous studies are confirmed showing a diurnal effect and that a degree of avoidance of entrainment by larvae is possible. It is concluded that entrainment of early life stages by Fawley Power Station does not significantly adversely affect local fish populations.     

Integration host factor and conjugative transfer of the antibiotic resistance plasmid R100.

Transfer of plasmid R100-1 was reduced 100-fold in the absence of integration host factor.