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A temperate haloarchaeal virus, SNJ1, was induced from the lysogenic host, Natrinema sp. J7-1, with mitomycin C, and the virus produced plaques on lawns of Natrinema sp. J7-2. Optimization of the induction conditions allowed us to increase the titer from ~10(4) PFU/ml to ~10(11) PFU/ml. Single-step growth curves exhibited a burst size of ~100 PFU/cell. The genome of SNJ1 was observed to be a circular, double-stranded DNA (dsDNA) molecule (16,341 bp). Surprisingly, the sequence of SNJ1 was identical to that of a previously described plasmid, pHH205, indicating that this plasmid is the provirus of SNJ1. Several structural protein-encoding genes were identified in the viral genome. In addition, the comparison of putative packaging ATPase sequences from bacterial, archaeal and eukaryotic viruses, as well as the presence of lipid constituents from the host phospholipid pool, strongly suggest that SNJ1 belongs to the PRD1-type lineage of dsDNA viruses, which have an internal membrane.

A novel transformation system, in which neither a nonphysiological concentration of Ca2+ and temperature shifts nor electronic shocks were required, was developed to determine whether Escherichia coli is naturally transformable. In the new protocol, E. coli was cultured normally to the stationary phase and then cultured statically at 37 degrees C in Luria-Bertani broth. After static culture, transformation occurred in bacteria spread on Luria-Bertani plates. The protein synthesis inhibitor chloramphenicol inhibited this transformation process. The need for protein synthesis in plated bacteria suggests that the transformation of E. coli in this new system is regulated physiologically.

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Compensatory growth is a phase of accelerated growth apparent when favourable conditions are restored after a period of growth depression. To investigate if F 2 common 'all-fish' growth hormone gene transgenic common carp (Cyprinus carpio) could mount compensatory growth, a 9 week study at 29°C was performed. The control group was fed to satiation twice a day throughout the experiment. The other two groups were deprived of feed for 1 or 2 weeks, respectively, and then fed to satiation during the re-feeding period. At the end of the experiment, the live masses of fish in the deprived groups were still significantly lower than those of the controls. During the re-feeding period, size-adjusted mean specific growth rates and mean feed intakes were significantly higher in the deprived fish than in the controls, indicating a partial compensatory growth response in these fish. No significant differences were found in food conversion efficiency between the deprived and control fish during re-feeding, suggesting that hyperphagia was the mechanism responsible for increased growth rates. The proximate composition of the deprived fish at the end of the experiment was similar to that of the control fish. This study is, to our knowledge, the first to report that fast-growing transgenic fish can achieve partial compensation of growth following starvation.