Chlorella is an attractive organism for complex recombinant protein production because of its eukaryotic characteristics and low cost for large-scale culture. Protoplasts of C. ellipsoidea were transformed with a vector containing the flounder growth hormone gene (fGH) under the control of the cauliflower mosaic virus 35S promoter, and the phleomycin resistance Sh ble gene under the control of the Chlamydomonas RBCS2 gene promoter. The presence of introduced DNA was first determined by PCR amplification of both the fGH and Sh ble genes from genomic DNA isolated from transformants and fGH protein expression was detected by immunoblot analysis. Over 400 microg of fGH protein expression per one liter culture containing 1 x 10(8) cells/ml was estimated by ELISA. Stable integration of introduced DNA was confirmed by Southern blot analysis of genomic DNA digested with restriction enzymes. The introduced DNA and fGH expression were detected after seven successive transfers in media devoid of phleomycin, but stably remained in the presence of the antibiotic. Flounder fry fed on the transformed Chlorella revealed a 25% growth increase after 30 days of feeding.

High mortality frequently occurs in larval mass production of Korean rock®sh, Sebastes schlegeli Hilgendorf. Nutritional de®ciencies in live feeds, rotifers and Artemia nauplii, fed to larvae could be a reason. A series of experiments was carried out to evaluate the effect of nutritional enrichment of live feeds by w-yeast, Spirulina powder and Super Selco TM on survival and growth rates in rock®sh larvae. Preference of rock®sh larvae for the live feeds was determined by analysis of stomach contents. In addition, the effect of green water produced by the use of Chlorella ellipsoidea and Spirulina powder on the growth performance of larvae was evaluated. Larvae fed rotifers nutritionally enriched with Super Selco showed signi®cantly higher survival rates than those fed rotifers enriched with w-yeast. Larvae fed rotifers that were nutritionally enriched with both Super Selco and Spirulina together exhibited improved growth and survival rates. Larvae fed Artemia nauplii nutritionally enriched with Spirulina powder showed signi®cantly higher survival than larvae fed Artemia nauplii without enrichment. When larvae were fed rotifers, Artemia nauplii or the mixture of rotifers and Artemia nauplii, the second and last group showed signi®cantly higher survival than the ®rst group. Fatty acid composition in live feeds was improved by enrichment of w-yeast and larvae fed this feed showed higher survival and growth rates compared with larvae fed nonenriched feeds. No positive effect of green water in the tank produced with C. ellipsoidea or Spirulina powder was observed on survival and growth rates for larvae fed nutritionally enriched rotifers with Super Selco and Spirulina powder. However, when the larvae were fed Artemia nauplii that were nutritionally enriched with w-yeast and Spirulina powder, green water obtained by adding Spirulina powder to the tanks resulted in signi®cantly higher growth rates of larvae than was obtained by adding C. ellipsoidea.

No abstract

This study was to determine the extent of bacteria contamination and resistance to various antibiotics used commonly in microalgal culture. Seven different dose levels of chloramphenicol, dihydrostreptomycin sulphate, neomycin, penicillin G, streptomycin sulphate, penicillin G + streptomycin sulphate, and penicillin G + streptomycin sulphate + chloramphenicol were added to each culture of microalgae. The lethal effects on microalgae and bacteria were the highest in chloramphenicol and the lowest in penicillin G. The axenic culture of bacillariophyceae and dinophyceae was more difficult than that of chlorophyceae and haptophyceae because of their complicate external morphology. The efficient antibiotics and their concentrations for axenic cultures varied with microalgal species. The optimum quantity for antibiotic treatments were 2,000 ppm of dihydrostreptomycin for Chlorella ellipsoidea, neomycin 500 ppm of Isochrysis galbana and Heterosigma ahashiwo, chloramphenicol 500 ppm of Cyclotella didymus, and dihydrostreptomycin sulphate and neomycin 6,000 ppm of Thalassiosira allenii.

The development and larval morphology of four venerid calms, Ruditapes phibppinurum, Muctru veneriformis, Cyclinu sinensis, and Meretrix lusoriu, which cohabit the intertidal zone in western coastal Korea, were compared using laboratory culture techniques. At 87 pm, the fertilized eggs of C. sinensis and M. Iusoriu were the largest and at 53 pm, those of M. venervorm's were the smallest. D-shaped larvae of M. lusoriu were the largest and those of M. veneriform's were the smallest measuring at 135 pm and 89 pm, respectively. D-shaped larvae of R. philippinurum and M. lusoriu had symmetrical shoulder angles and an elliptical ventral form, in contrast to the asymmetrical shoulder angles and round ventral forms of M. veneriformis and C. sinensis. In general, pediveliger larvae of all species in the study were yellow, but those of M. veneriforks and C sinemis were a more pronounced yellow. In between the early D-shaped and pediveliger stage, 7 and 17 d elapsed for M. lusoniu and C. sinensis larvae, respectively. In the early larval stages for all species, the sheU length was longer than the height. However, shell length and height later became approximately the same size in all species except R. philippinurum, which exhibited a flat shape. These results indicate that for these four venerid clams, the different characteristics in larval growth and external morphology provide the evidence necessary for larval identification of natural seed production despite the fact that they spawn concurrently in the intertidal zone.