Effect of combination feeding of Nannochloropsis and freshwater Chlorella on the fatty acid composition of rotifer Brachionus plicatilis in a continuous culture

金沢大学大学院自然科学研究科 信頼性システム工学A continuous culture of rotifer was conducted to investigate the effect of combination feeding of both a high density of Nannochloropsis oculata (N) and condensed freshwater Chlorella (FC) on the fatty acid composition of L-type rotifer Brachionus plicatilis in a continuous culture system. The algal feeding of the rotifers was carried out in three successive steps: N-feeding → N+FC-feeding → FC-feeding. The culture was conducted at 24°C and 25-27 psu in a 2000 mL bottle with 50% of water exchanged daily. The combination N+FC-feeding was effective in increasing rotifer density. The rotifers fed on N+FC (N+FC-R) had more non-polar lipids than polar ones, similar to those on N (N-R), opposite to the rotifers fed on FC (FC-R). N+FC-R contained higher levels of 16:2, 18:2n-6 (linoleic acid [LA]) and 20:2n-6, but lower levels of 18:1, 20:4n-6 (arachidonic acid), 20:5n-3 (eicosapentaenoic acid [EPA]) and 22:5n-3 (docosapentaenoic acid [DPA]) compared with N-R. Whereas N+FC-R contained higher levels of 16:1n-7, EPA and DPA, but lower levels of 16:2 and LA compared with FC-R. N+FC-R had more DPA in polar lipids than in non-polar ones. The Σn-6/Σn-3 ratio in N+FC-R was 0.9-1.0, significantly different from those in N-R (0.4) and FC-R (6.6-8.4). Therefore, it is inferred that the fatty acid profile of the N+FC-R cultured in a continuous culture system was affected by both N and FC. Also, the combination N+FC-feeding may be effective in manipulating the Σn-6/Σn-3 ratio in continuously cultured rotifers. © 2008 Japanese Society of Fisheries Science

Introduction for Fisheries and Aquatic Biology

Chapter I. Aquatic Environment. Ken FURUYA and Ichiro YASUDA : chapter_1.pdfChapter II. Biology and Ecology of Aqua-Shere. Toyoji KANEKO, Katsumi TSUKAMOTO, Atsushi TSUDA, Yuzuru SUZUKI and Katsufumi SATOH : chapter_2.pdfChapter III. Aquatic Resource and Production. Ichiro AOKI, Kazuo OGAWA, Taku YAMAKAWA and Tomoyoshi YOSHINAGA : chapter_3.pdfChapter IV. Chemistry of Aquatic Organism and Their Utilization. Hiroki ABE, Shugo WATABE, Yoshihiro OCHIAI, Shigeru OKADA, Naoko YOSHIKAWA, Yoshiharu KINOSHITA, Gen KANEKO and Shigeki MATSUNAGA : chapter_4.pdfChapter V. Relation between Aqua-Shere and Human Life. Hisashi KUROKURA, Hirohide MATSUSHIMA, Shingo KUROHAGI, Haruko YAMASHITA, Akinori HINO, Kazumasa IKUTA, Satoquo SEINO, Masahiko ARIJI, Ken FURUYA, Junichiro OKAMOTO and Nobuyuki YAGI : chapter_5.pdfPart of "Introduction for Fisheries and Aquatic Biology

Behaviour of clay subjecting to vacuum and surcharge loading in an oedometer

The deformation of clayey soil subjected to the combination of a vacuum pressure and a surcharge load in an oedometer apparatus, with either vertical or inward radial drainage, has been investigated experimentally. A parameter Kw, defined as the horizontal effective stress exerted on the wall of the consolidation ring (σ'hw) divided by the vertical effective stress (σ'v) in the soil specimen is suggested as an indicator of the tendency for lateral deformation under field conditions. It is observed that if the value of Kw is close to the value of K0 of the soil (the 'at-rest' earth pressure coefficient), there should be very limited lateral displacement in field situations. The laboratory test results show that during the loading process, the value of Kw is mainly influenced by the ratio of the magnitude of the surcharge pressure to the vacuum pressure (RL) and the rate of surcharge loading (SLR). At the end of consolidation the value of Kw increases with increasing RL, but it is almost independent of SLR for the conditions investigated. In the presence of a vacuum pressure, at the end of consolidation the value of Kw is usually less than the original value of K0 of the soil. The test results also indicate that Kw has a strong correlation with the synthetic non-dimensional loading parameter, RLS, as defined by Chai et al. (2013), which includes the effects of both RL and SLR as well as the consolidation properties of the soil. It is suggested that the parameter RLS can be used to predict lateral displacements under field conditions that involve combined surcharge and vacuum pressure loading