Viability of frozen algae used as food for larval penaeids

Freezing with added chemicals as flocculants and protectants was assessed as a means of preserving stock cultures of 4 algal species used for larval penaeid food Chaetoceros calcitrans, Skeletonema costatum, Tetraselmis chuii and Isochrysis galbana. The maximum storage effectability of the preservation techniques for each species was also determined.

Embryonic and larval development of Mystus gulio (Ham.)

Mystus gulio eggs are strongly adhesive and contain relatively small yolk (0.75-1.0 mm). The egg envelop is thick and transparent. First cleavage (two cells), four cells, eight cells, sixteen cells and multi cells stages were found 20, 25, 35-40, 60 and 70 minutes after fertilization, respectively. The morula stage was visualized within 1.5 h after fertilization. The heart beat visible and the circulatory system commenced after 16 h of fertilization. Embryos hatched 18-20h after activation of egg. The newly hatched larva measured 2.82±0.03 mm in length and 0.32±0.06 mg in weight. The yolk sac was fully absorbed by the third day though larvae commenced exogenous feeding even before completion of yolk absorption. A 5-day old post larva began wandering in search of food. Ten-day old post larvae endowed with eight branched rays in dorsal fin and seven in caudal fin. Fifteen-day old post larvae had the pectm:al spine become stout though the embryonic fin folds had to be disappeared. The length of fingerlings ranged from 25-30 mm after 30 days, and their external features were just like those of an adult except that they were not sexually matured.

Histology and hormonal effect of Ghrelin on ovary of Benni (Barbus sharpeyi) in order to study sexual maturity, zygote and larval generation

Benni (Barbus sharpeyi) is valuable fish that Khuzastan fisheries office propagated it artificially in Susangerd Fish Propagation Center every year. Pituitary gland is used for this aim but female fish lost their fertilization power after 2-3 years, so in present research, new hormone, that is called Ghrelin. The aims of this research are histology, hormonal, zygote and larval generation studies and comparing the results with each other. Ghrelin is a multifunctional peptidyl hormone which increases GTH-II in fish, amphibian, and birds and mammalian so its effect on Benni sexual maturation was studied. Human Ghrelin (hGRL) was obtained from ANASPEC, Canada, with 28 amino acids. In the present study, three levels of ghrelin including 0 (sham treatments), 0.10 (treatment 1) and 0.15 μg/g (treatment 2) body wt and one level of pituitary gland 4000 μg/g (pituitary treatment) with two replications were used. 56 specimens were injected intraperitonealy and their ghrelin level was evaluated immediately after injection and after 24 h. Control fish(n=16) were just injected by physiological saline. For hormonal studies sham and experimental fish(n=40) were anesthetized with MS-222 at a concentration of 250 mg l-1, and blood samples were collected and kept at 4ْC, then spun to collect serum. Serum samples were stores at -20ْC until the RIA for CTH-II. For histology studies immediately after injection a piece of ovary was collected from control fish (Sham zero) after being anesthetized. The sampled ovaries were fixed in Buin solution and embedded in paraffin, and stained to Sections of 5–6 μm using haematoxylin and eosin. The ovarian samples were performed with a compound microscope. Histology and micrometry studies had done. The mature oocytes had given from mature fish, then weighted and the working fecundity were counted. The mature oocytes fertilized, the eggs were incubated and the percentage of fertilization was calculated. After 72h the eggs hatched and the percentage of hatch was counted. The percentage of hindrance was calculated after 6 days. Hormonal results indicate that ghrelin and pituitary increase significantly the GTH-II level in comparison to sham. Macroscopic observations (before taking ovary) showed that ovaries with green colored have couple oval structure located in the abdominal cavity. Microscopic studies of dissected ovaries indicated simultaneous growth of 127 oocytes with 6 stages. The type of the ovary is asynchronous. The results indicated that both of the ghrelin treatment increased the percentage of mature follicles followed by decrease of immature follicles. There were significant differences (P<0.05) between the number of mature and immature follicles. Average diameter of follicle in both of the ghrelin treatment was significantly (P<0.05) declined in the stages of the vitellogenesis when the result compared to the other treatment. Just treatment 1 and pituitary treatment can give mature oocytes. The fecundity of pituitary treatment significantly increase in comparision to ghrelin treatment (P<0.05). In food-restricted fish where endogenous ghrelin levels are known to be increased, a chronic administration of ghrelin induces overt negative effect in releasing mature oocytes. The percentage of fertilization was significantly increase (P<0.05) in ghrelin t. in comparison to pituitary t. and the percentage of hatch was significantly increase (P<0.05) in pituitary t. in comparison to ghrelin t. There was no significant difference (P>0.05) in terms of percentage of hindrance between treatments. In conclusion, the present study demonstrated that ghrelin has positive effect on the level of GTH-II, oocyte maturation, ovarian vitellogenesis and the number of mature follicles of Barbus sharpeyi ovary. Increasing of the mature follicles number reduces their average diameter, indicating stimulating effect of ghrelin in sexual maturation of Barbus sharpeyi.The ghrelin and pituitary treatment have equal chance in the post-stage of spawning.

The application of in vitro sperm competition test to evaluate the impact of ZP-derived peptides on fertilization capacity of cat sperm

The present study aimed to establish a sensitive in vitro assay to assess the binding capacity of cat spermatozoa. Cat oocytes and epididymal sperm cells were isolated from gonads and cultured for in vitro fertilization. Before fertilization, the sperm ce

Survey of food supplementary (Pseudomonas fluorescence) and live food (Algae and brine shrimp) on Penaeus indicus larval stages

In this study ,the effects of Pseudomonas fluorescence obtained from generator pond water of Kolahi as supplementary and four algae consisting of : Chaetoceros sp, Chlorella and Skeletonema sp and Tetraselmis sp, three types of artemia as live food larval states from zoa to postlarvae (PL4 ) Penaeus indicus were investigated. The results indicate that Pseudomonas fluorescence has positive effect on Penaeus indicits larvae growth and their living food. Effective ranges at minimum and maximum were estimated. In most cases optimum dosage was approximately determined. Optimum dosage is between 50 -150 milligrams per liter for living food and Penaeus larval More than 200 milligram per liter resulted in a negative effect on the growth and survival. Also the results indicate Uromiana artemia. Requires a higher concentration of the bacteria the imported artemia. As a conclusion it is recommended to introduce Pseudonionas fluorescence as a new medium for the growth of some mentioned algae .

Notes on the larval rearing scheme at SEAFDEC/AQD

For tiger shrimp, milkfish, and sea bass, larval rearing starts with the hatching of artificially spawned eggs. The eggs are stocked in larval rearing tanks, hatched, and metamorphosed larvae are fed and reared with good water management. Fry are harvested after about 30 days.

Observaciones sobre la reproducción, desarrollo embrionario y larval de la anchoíta argentina (Engraulis anchoita)

The first studies on the problems related to the reproduction of marine fish in Argentina (SW Atlantic ocean) have been carried out with a species of great economic importance, the anchovy (Engraulis anchoita Hubbs and Marini). The spawning period of this species during the period 1963-64 has been determined. By the application of the quantitative collection method, it has been established that spawning commenced in the areas close to the coast during the first few days of September and at a water temperature of 10,3° C and reached its greatest intensity in October (up 1569 eggs/1 square metre surface water) at a temperature varying between 11,5-13,8° C. From the middle of November the anchovy continues to reproduce in a less intensive form and further out to Sea, up to at least the month of May. The intensity of reproduction reaches a peek in February, and at a water temperature of 20° C. It is believed that two physiologically distinct populations of Engraulis anchoita may exist, the first reproducing in Spring and the second in Autumn. It has been established that a daily spawning rhythm occurs, between the hours of 8 and 12 p. m. During this period it was possible to obtain mature females with which artificial fertilization was performed. The rate of development was determined, which at a temperature of 14-15° C is from 69-72 hours, and at a temperature of 19-20° C from 50-53 hours. A temperature of 49° C was found be lethal. The different embryonic and larval stages of development are illustrated diagramatically and individually described. The preliminary studies on the larvae and juveniles caught in the Sea during the period of reproduction led to the formulation of certain conclusions whith reference that the juveniles, as yet larvae, begin to group together at an early age, and the younger individuals the more uniform are the schoals whith regards to the total size of the specimens. It has shown that the anchovy during its first year of life tends to display littoral behaviour. RESUMEN EN ESPAÑOL: Los primeros estudios de los problemas referentes a la reproducción de los peces marinos en la Argentina (océano Atlántico sudoccidental) se han efectuado sobre una especie de gran importancia económica, Engraulis anchoita Hubbs y Marini. Se ha determinado la época de desove de la anchoíta en un período anual 1963-64. Aplicando el método de recolección cuantitativo se ha establecido que el desove de esta especie ha empezado en las zonas muy cercanas a la costa, en los primeros días de setiembre a la temperatura 10,3° C y ha alcanzado mayor intensidad en octubre (hasta 1569 huevos en 1 m2 de la superficie del agua) a la temperatura 11,5°-13,8° C. Desde mediados de noviembre la anchoíta sigue reproduciéndose en forma poco intensiva y más mar afuera, hasta por lo menos el mes de mayo. La intensidad de reproducción para este segundo período alcanza un pico, aunque muy pequeño en febrero a la temperatura 20° C. Se hace la suposición de que pueden existir dos de distintas características fisiológicas poblaciones de Engraulis anchoita una de reproducción primaveral y otra de reproducción otoñal. Además se ha establecido que existe un ritmo diario de desove que comprende las horas 20-24. En las horas de postura se pudo conseguir hembras maduras y con sus productos sexuales se efectuó la fecundación artificial. Se determinó la velocidad de desarrollo que a la temperatura 14°-15° C es de 69-72 horas y en la temperatura 19°- 20° C es de 50-53 horas. La temperatura 4° resultó ser letal. Se realizaron dibujos y descripciones correspondientes a los distintos estadios embrionarios y larvales. Los estudios preliminares de las larvas y juveniles de la anchoíta, capturados en el mar en la época de reproducción, permitieron sacar ciertas conclusiones sobre el crecimiento en sus primeros meses de vida. Se observó que los juveniles, larvas todavía, empiezan a agruparse muy temprano y cuanto más jóvenes son los individuos, tanto más uniformes son los cardúmenes en las dimensiones de los ejemplares. Se demostró que la anchoíta en su primer año de vida tiene costumbres muy costeras.

Analysis of competition in the wholesale and retail markets for fish in Kisumu, Kenya

This study analyses competition in the wholesale and retail fish marketing system in Kisumu, which is Kenya's largest fish market. It is based on cross sectional and time series primary data collected in a survey involving 88 retailers and 47 wholesale traders of fish in the town. Stratified random sampling method was used in selecting the respondents, Concentration ratios, Lorenz curves and Gini coefficients are derived and evaluated for both markets. They demonstrate that market shares are unequally distributed among the wholesalers and retailers. The Gini coefficients are 0.37 and 0.45 for the whole and retail markets respectively. Based on a Gini coefficient cut-off level of 0.4, it is concluded that the wholesale fish market exhibits effective competition while the retail outlet has oligopolistic tendencies. The implication of this level of competition to price efficiency is discussed. Intervention measures to enhance competition in the market are recommended.

MATING COMPETITION AND INTERGROUP TRANSFER OF MALES IN TIBETAN MACAQUES (MACACA-THIBETANA) AT MT EMEI, CHINA

In five groups of seasonally provisioned Tibetan macaques (Macaca thibetana) at Mt. Emei, males were sampled for wounds as an indicator of their competition for females during about 80 days in the 1987 mating season. Quantitative data on intergroup transfer were collected in a period between June 1986 and December 1987. The young adult (YA) males, the most active age-class in mating activity and intergroup transfer, received most of the wounds. Wounds tended to appear more in the front of body for YA and subadults (SA) than they did for middle-old aged (MO) males. This implies that some of the MO males were more active and aggressive in the fights. During the 1.5 year period, 5/6 of the YA and 5/17 of the MO males made intergroup shifts. Although YA males faced a high risk of receiving wounds at transfer, they usually rose in rank. On the other hand, the MO males transferred more smoothly but dropped in rank. The peripheral SA males, which rarely emigrated in the population, were an active component in determining the wounding rate, and the rate and direction of male migration. Three SA immigrants died of severe attacks made by resident males in 1988 and 1991. Adult sex ratios and their variations were considerably reduced with male nonrandom shifts and better conservation of the population.

Effects of pure microcystin-LR on the transcription of immune related genes and heat shock proteins in larval stage of zebrafish (Danio rerio)

Microcystins (MCs) are cyanobacterial toxins in water blooms that have received increasing attention as a public biohazard for human and animal health. Previous studies were mainly focused on the toxic effects on adult fish, rather than juvenile or larvae, and the response of fish immune system were usually neglected. This paper presents the first data of the effects of microcystin-LR (MC-LR) on transcription of several genes essential for early lymphoid development (Rag1, Rag2, Ikaros, GATA1, Lck and TCR alpha) and heat shock proteins (HSP90, HSP70, HSP60, HSP27) in zebrafish larvae. Relative changes of mRNA transcription were analyzed by real time PCR. The transcription of Rag1, Rag2, Ikaros, GATA1, Lck and TCR alpha were up-regulated when following exposure to 800 mu g/L MC-LR, which may indicate that specific lymphocytes differentiation and TCR/lg arrangement are induced to counteract the toxic effects of MC-LR. It was also interesting to note the dramatically increased transcription of HSP90. HSP70, HSP60 and HSP27, which may indicate their important roles as molecular chaperones under oxidative stress. (C) 2009 Elsevier B.V. All rights reserved.

Feeding rates affect heat shock protein levels in liver of larval white sturgeon (Acipenser transmontanus)

A two-week trial was conducted to study the effect of feeding rates on heat shock protein levels in larval white sturgeon. The larvae (30 day post hatch, 230 mg initial body weight) were fed a commercial feed (12.6% moisture, 49.5% crude protein. 20.7% Crude fat, and 8.6% ash) at 5, 15. or 25% body weight per clay (BW d(-1)). Liver heat shock proteins (Hsp) were measured before and after the larvae were subjected to a heat shock from 18 to 26 degrees C at 1 degrees C/15 min and maintained at 26 degrees C for 4 h thereafter. Before heat shock, larvae fed 5% BW d(-1) had significantly (P<0.05) lower final body weight, RNA/DNA ratio, whole body lipid and protein content, and Hsp60 and Hsp70 levels but higher protein efficiency ratio, and whole body moisture content than larvae fed the two higher feeding rates. Heat shock significantly induced Hsp60 and Hsp70 levels in the liver of all fish but they were lower in larvae fed the 5% than those fed 15 and 25% BW d(-1). Hsp70 level increased much more than Hsp60 after the heat shock Suggesting that Hsp70 is a more sensitive biomarker under our experimental conditions. (c) 2008 Elsevier B.V. All rights reserved.

Apo-14 is required for digestive system organogenesis during fish embryogenesis and larval development

Apo-14 is a fish-specific apolipoprotein and its biological function remains unknown. In this study, CagApo-14 was cloned from gibel carp (Carassius auratus gibelio) and its expression pattern was investigated during embryogenesis and early larval development. The CagApo-14 transcript and its protein product were firstly localized in the yolk syncytial layer at a high level during embryogenesis, and then found to be restricted to the digestive system including liver and intestine in later embryos and early larvae. Immunofluorescence staining in larvae and adults indicated that CagApo-14 protein was predominantly synthesized in and excreted from sinusoidal endothelial cells of liver tissue. Morpholino knockdown of CagApo-14 resulted in severe disruption of digestive organs including liver, intestine, pancreas and swim bladder. Moreover, yolk lipid transportation and utilization were severely affected in the CagApo-14 morphants. Overall, this data indicates that CagApo-14 is required for digestive system organogenesis during fish embryogenesis and larval development.

The role of cell-surface-bound phosphatases in species competition within natural phytoplankton assemblage: an in situ experiment

Despite it is widely acknowledged that the ability to hydrolyze dissolved organic matter using extracellular phosphatases is diverse in fresh water phytoplankton, the competition within single species related to presence and quantity of cell-surface-bound phosphatases has not been examined in natural conditions yet. Here, we studied phytoplankton species competition in a freshwater reservoir during an in situ experiment. A natural plankton community, with the exclusion of large zooplankton, was enclosed in permeable dialysis bags inside two large containers of different bioavailable phosphate concentrations. Phytoplankton species biomass and the abundance of bacteria were determined in purpose to compare the development of enclosed microbial communities. Total and cell-surface-bound phosphatase activities in the phytoplankton were investigated using the Fluorescently Labelled Enzyme Activity (FLEA) technique that allows for direct microscopic detection of phosphatase-positive cells and, with image cytometry, enables quantification of phosphatase hydrolytic capacity. Production of extracellular phosphatases was not completely inhibited or stopped in the phosphate-enriched environment, phytoplankton cells only showed the activity less often. Under the phosphate-nonenriched conditions, the production of phosphatases was enhanced, but active species did not proliferate amongst phytoplankton assemblage. Further, specific growth rates of the phosphatase-positive species in the non-enriched environment were lower than the same phosphatase-positive species in phosphate-enriched environment. Interestingly, the phosphatase-positive cells of Ankyra ancora increased their size in both treatments equally, although the population in phosphate-enriched environment grew much faster and the cell-specific phosphatase activity was lower. We hypothesize that brand new daughter cells had sufficient phosphorus reserves and therefore did not employ extracellular phosphatases until they matured and needed extra bioavailable phosphorus to support their metabolism before cell division. Based on presented in situ experiment, we propose that the ability to hydrolyze organic polymers and particles with cell-surface-hound phosphatases is advantageous for longer persistence of given population in a phosphate-scarce environment; although phosphatase-positive species cannot dominate the reservoir phytoplankton solely because of specific phosphorus-scavenging strategy.