Now showing items 1-3 of 3

    • Article

      Cryopreservation of different strains of the euryhaline rotifer Brachionus plicatilis embryos 

      JD Toledo, H Kurokura & H Nakagawa - Nippon Suisan Gakkaishi, 1991 - Japanese Society of Fisheries Science
      Cryopreserevation of different strains of Brachionus plicatilis symmetrical stage embryos was conducted. One S-type strain, namely Yashima-S (YS), and three L-type strains, namely Yashima-L (YL), Nagasaki (NG), and Hamana (HA), were used. Symmetrical stage embryos in 10% DMSO-28‰ sea water solution were frozen at -196°C using a two-step freezing procedure; the embryos were first cooled slowly from -5°C to -20°C at a rate of 0.3°C/min and then cooled rapidly by direct transfer to liquid nitrogen. Frozen samples were thawed in a gently stirred water bath at room temperature.

      A mean survival rate of 36% after 30 days storage in liquid nitrogen of HA strain was significantly lower than YS (55%), YL (58%), and NG (54%), and is due likely to its relatively larger embryo volume. There was no significant difference in the intrinsic rate of increase (r) between strains among clones taken from the cryopreservation or unfrozen control group. The results also indicate that various strains of B. plicatilis embryos can be cryopreserve without seriously altering their reproductive capability. The freezing method described could be of great potential in aquaculture and in future studies on rotifer genetics.
    • Article

      Effect of some vertebrate and invertebrate hormones on the population growth, mictic female production, and body size of the marine rotifer Brachionus plicatilis Müller 

      WG Gallardo, A Hagiwara, Y Tomita, K Soyano & TW Snell - Hydrobiologia, 1997 - Springer Verlag
      Eight vertebrate and invertebrate hormones were screened for their effect on population growth, mictic female production, and body size of the marine rotifer Brachionus plicatilis. Growth hormone (GH) or human chorionic gonadotropin (HCG) at 0.0025-25 I.U. ml-1 and estradio1-17β (E2), triiodothyronine (T3), 20-hydroxyecdysone (20-HE), 5-hydroxytryptamine(5-HT), gamma-aminobutyric acid (GABA) or juvenile hormone (JH) at 0.05-50 mg l-1 were added to 5-ml of Nannochloropsis oculata suspension (7 x 106 cells ml-1). From an initial density of 1 individual ml-1, rotifers were cultured with hormones for 48 hours in 22 ppt seawater at 25 °C, in darkness. Rotifers were counted and classified into female types and transferred to a new algal food suspension without hormone every other day until day 8 when body size was measured. Population growth was significantly higher in treatments exposed to GABA (50 mg l-1), GH (0.0025 and 0.025 I.U. ml-1), HCG (0.25 and 2.5 I.U. ml-1), and 5-HT (5 mg l-1). E2 caused a decrease in population growth, whereas JH, 20HE, and T3 had no effect. Mictic female production was significantly higher at 0.05 and 0.5 mg l-1 JH and 0.05 and 5 mg l- 5HT. GH (0.0025 and 0.025 I.U. ml-1), E2 (50 mg l-1 ), GABA (0.5, 5 and 50 mg l-1), and 20-HE (0.05 mg l-1) treatments had significantly higher mictic female production only on day 8, 6, 4, and 6, respectively. T3 and hCG had no effect on mictic female production. Lorica length increased by 9.6% and 4.4% in rotifers treated with JH (0.05 mg l-1) and GABA (5 mg l-1), respectively. Correspondingly, lorica width increased by 8.9% and 2.6% in these treatments. In comparison, 20-HE-, T3-, and HCG-treated rotifers were smaller (3.9-8.2%) and GH, 5-HT and E2 had no effect on rotifer body size.
    • Article

      The macronutrient composition of natural food organisms mass cultured as larval feed for fish and prawns 

      OM Millamena, VD Peñaflorida & PF Subosa - The Israeli Journal of Aquaculture-Bamidgeh, 1990 - Society of Israeli Aquaculture and Marine Biotechnology
      The macronutrient composition of natural food organisms that are mass cultured as feed for the larval stages of fish and prawns in the SEAFDEC Aquaculture Department was determined by chemical analysis. The food organisms included five species of marine phytoplanktons (algae): Chaetoceros calcitrans, Skeletonema costatum, Tetraselmis chui, Chlorella vulgaris and Isochrysis galbana, and two zooplanktons: Artemia sp. nauplii (San Francisco Bay strain) and Brachionus plicatilis. The algal species were grown in batches on Guillard and Ryther media and harvested during the exponential phase of growth using a procedure which preserved cellular integrity and prevented cell lysis. The zooplankton were cultured using standard techniques adopted at the SEAFDEC Larval Food Laboratory. Each species was analyzed for proximate composition (protein, fat, fiber and ash) and for mineral content (calcium and phosphorous). Nitrogen-free extract (NFE) was determined by difference. For the five algal species, the protein, fat and NFE contents varied from 22% to 48%, 2% to 16% and 14% to 24%, respectively. The zooplanktons had higher protein and fat contents than any of the phytoplankton species except I. galbana which had the highest fat content. On the other hand, the phytoplanktons, particularly the diatoms which have a siliceous cell wall, contained significantly higher quantities of inorganic matter (ash). C. vulgaris had the highest fiber content which may be attributed to its cellulosic cell wall.