Search

To examine the effect of cold shock treatment on the fatty acid composition of Aurantiochytrium limacinum strain mh0186, a marine thraustochytrid, we cultivated this strain at 28°C for 72 h with shaking and stored the obtained biomass at 10°C for 72 h. A growth experiment was carried out for comparison, wherein strain mh0186 was grown at 10 and 15°C for 72 h with shaking, and it was found that the unsaturation of fatty acids was accelerated relative to that at 28°C. In the cold shock experiment, the total lipid content significantly increased during storage at 10°C for 72 h. Overall, the percentage of unsaturated fatty acids such as docosahexaenoic acid was almost stable while that of n-6 docosapentaenoic acid decreased slightly, but significantly, relative to that in the growth experiment.

The growth, lipid content, and fatty acid composition of Aurantiochytrium sp. strain mh0186 at different temperatures were investigated. Strain mh0186 grew well at 15-30 degrees C, but weakly at 10 degrees C. The biomass at 15-30 degrees C was significantly higher than at 10 and 35 degrees C, and the total lipid at 15-35 degrees C was significantly higher than that at 10 degrees C. The amount of DHA in the total fatty acid was highest at 10 degrees C and decreased in response to temperature increase. The content of DHA (mg/g-dry cell weight) at 15-30 degrees C were significantly higher than those at 35 degrees C and those at 15-25 degrees C were significantly higher than those at 10 and 35 degrees C. The DHA yield at 15-35 degrees C was significantly higher than those at 10 and 35 degrees C. Unsaturation of fatty acid was regulated by temperature and was enhanced in response to temperature decrease. The ratio of DHA to DPA varied at different temperatures.

In recent years, kisspeptin peptides, encoded by kiss genes have been used to manipulate reproductive processes in farmed animals, including fish. Our previous studies demonstrated that the chub mackerel brain expresses kiss1 and kiss2 and intramuscular injection of synthetic Kiss1 pentadecapeptide (Kiss1-15) but not Kiss2 dodecapeptide (Kiss2-12) accelerates spermatogenesis in prepubertal male chub mackerel ( Scomber japonicus). In the present study, we evaluated their effects in prepubertal female chub mackerel. The gonadosomatic index ( GSI) values of experimental fish did not show any significant changes. Condition factor ( CF) values increased significantly in Kiss1-15 treated fish, in comparison with control and Gn RH analogue (Gn RHa) injected fish. Histologically, only perinucleolar oocytes were found in all experimental fish. However, Kiss and Gn RHa treated fish showed a significant increase in the perinucleolar oocyte diameter, in comparison with the control fish. Gene expression analyses revealed decreased expression of gnrh1 in the telencephalon-preoptic region of the brain of Kiss2-12 and Gn RHa injected fish, in comparison with control fish. In contrast, Gn RHa injected fish exhibited higher levels of fshβ in the pituitary, with no changes in the levels of lhβ among different treatments. Levels of circulating sex steroids, testosterone, and estradiol-17β were significantly higher in Kiss1-15 injected fish, in comparison with control fish. These results indicate that synthetic kisspeptin peptides and Gn RHa can induce oocyte growth in prepubertal female chub mackerel. [ABSTRACT FROM AUTHOR]

Abstract: Thraustochytrium aureum ATCC 34304 was grown in the presence and absence of polyoxyethylene sorbitan monooleate (Tween 80). The aim of this work was to obtain basic knowledge about the effect of Tween 80 on growth, lipid accumulation and fatty acid composition in T. aureum. The addition of Tween 80 to a culture medium significantly enhanced the growth of T. aureum, and the biomass increased with an increase of Tween 80 content. Total lipid content and total fatty acid content were significantly higher in 1.0% Tween 80 in comparison with the control (absence of Tween 80). The fatty acid profile showed that the content of C18:1n-9 (oleic acid) significantly increased as a result of the addition of Tween 80. These results indicated that part of the Tween 80 added to the medium was utilized as a carbon source or that the oleate included in Tween 80 was directly incorporated into T. aureum cells as a fatty acid. Neither the DHA content nor the percentage of DHA did not change in spite of the addition of Tween 80. However, the DHA yield significantly increased because the biomass increased due to the addition of Tween 80. [Copyright &y& Elsevier]