Penaeus monodon larvae can be protected from Vibrio harveyi infection by pre-emptive treatment of a rearing system with antagonistic or non-antagonistic bacterial probiotics

This study shows that the disease resistance and survival rate of Penaeus monodon in a larval rearing systems can be enhanced by supplementing with antagonistic or non-antagonistic probiotics. The antagonistic mode of action of Pseudomonas MCCB 102 and MCCB 103 against vibrios was demonstrated in larval mesocosm with cultures having su⁄cient concentration of antagonistic compounds in their culture supernatant. Investigations on the antagonistic properties of Bacillus MCCB 101, Pseudomonas MCCB 102 and MCCB 103 and Arthrobacter MCCB 104 against Vibrio harveyi MCCB111under in vitro conditions revealed that Pseudomonas MCCB 102 and MCCB 103 were inhibitory to the pathogen.These inhibitory propertieswere further con¢rmed in the larval rearing systems of P. monodon. All these four probionts signi¢cantly improved larval survival in long-term treatments as well as when challengedwith a pathogenic strain ofV. harveyiMCCB111. We could demonstrate that Pseudomonas MCCB 102 andMCCB103 accorded disease resistance and a higher survival rate in P. monodon larval rearing systems throughactive antagonism of vibrios,whereas Bacillus MCCB 101 and Arthrobacter MCCB 104 functioned as probiotics through immunostimulatory and digestive enzyme-supporting modes of action.

Vibrios associated with Macrobrachium rosenbergii (De Man, 1879) larvae from three hatcheries on the Indian southwest coast

Surveys for bacteriological analysis of larval samples to isolate the associated vibrios were carried out during 1985^1992, 2001 and 2002 in three di¡erent hatcheries located on the southwest coast of India. Vibrio isolates were examined for their species diversity, virulence based on haemolysis in prawn blood agar, lipolysis, proteolysis and chitinolysis and antibiotic sensitivity.Vibrio cholerae was the predominant species in the apparently healthy larval samples, whereas V. alginolyticus and V. vulni¢cus dominated during disease and morbidity. No correlation was found between the hydrolytic properties and haemolytic activity of the vibrios associated with the larvae. All isolates were resistant to erythromycin and resistance to oxytetracycline, ampicillin and streptomycin sulphate was prevalent among the larger section of the Vibrio population. This suggested that antibiotic application may not be of much use to protect the larvae fromvibriosis. This is the ¢rst report on the diversity of Vibrio species associated with Macrobrachium rosenbergii larvae and their virulence characteristics based on haemolysis in prawn blood agar

An inhibitory compound produced by Pseudomonas with effectiveness on Vibrio harveyi

Persistence of the antivibrio property of the potential antagonistic probiotics, Pseudomonas MCCB 102 and 103, at di¡erent temperatures, pH and in organic solvents was studied. The antivibrio compound was extracted, puri¢ed and characterized using thin-layer chromatography, high-pressure liquid chromatography, liquid chromatography-mass spectroscopy, UV^ Vis and nuclear magnetic resonance spectroscopy and identi¢ed as N-methyl-1-hydroxyphenazine, a phenazine antibiotic. The toxicity of the compound was tested in Penaeus monodon haemocyte culture and the IC50 valuewas found to be1.4 0.31mg L 1. The compound was found to be bacteriostatic at 0.5mg L 1. Its stability to varying temperature, pH, organic solvents, prolonged shelf-life and vibriostatic nature point to its suitability for prophylatic aquaculture application.

Alkali insoluble glucan extracted from Acremonium diospyri is a more potent immunostimulant in the Indian White Shrimp, Fenneropenaeus indicus than alkali soluble glucan

E¡ect of an extraction method on the structure of glucan and its immunostimulatory response in Fenneropenaeus indicus was investigated. Here we extracted alkali insoluble glucan (AIG) and alkali soluble glucan (ASG) from a ¢lamentous fungi Acremonium diospyri following alkali^acid hydrolysis and the sodium hypochlorite oxidation and dimethyl sulphoxide extraction method respectively. Structural analysis showed that 85% of glucan in AIG was a (1 !3)-b-D-glucan and it increased the prophenoloxidase and reactive oxygen intermediate activity when administered to F. indicus. On the other hand, ASG, which contained 93% (1 !3)-a-glucan, did not induce signi¢cant immune response in shrimp. Here we report that the di¡erence in immunostimulatory potential between AIG and ASG is due to the di¡erence in the percentage of (1 !3)-b-D-glucans present in each preparation, which varies with the method of extraction employed. Also our observations suggest that glucan can be used as a potential immunostimulant to shrimp, provided it contains (1 !3)-b-D-glucan as the major fraction.

A simple device for the separation of weak larvae of Macrobrachium rosenbergii (De Man)

Larvae of Macrobrachium rosenbergii (De Man) are photopositive (Ling 1969a.b) and negatively rheotactic. While investigating larval diseases of M, rosenbergii it was observed that weak larvae failed to show both these responses. It was felt that this lack of response could be used to develop a device for separating the weak larvae from the apparently healthy ones. Such a device would be a valuable tool for assessing the health of a batch in terms of the percentage of 'healthy' and 'weak' larvae. What follows is a description and mode of operation of the 'photo-flow' device developed by the authors

Chitosan as a wall material for a microencapsulated delivery system for Macrobrachium rosenbergii(de Man) larvae

Chitosan has beenwidely accepted as awall material for preparing microcapsules of various purposes in human medicine. The possibility of using chitosan as a wall material for microencapsulating nutrients and drugs for aquaculture purposes, speci¢cally to Macrobrachium rosenbergii larvae was evaluated in this study. Two types of chitosan-coated microcapsules were prepared using either acetone (MEC-A) or NaOH (MEC-N) as the cross-linking agents. They were compared with a microbound diet relative to total leaching of nutrients and free amino acids (FAA). Among the microcapsules, MEC-N showed the lowest level of total leaching of nutrients (23.3%) during 5 h of immersion in seawater and released 65% FAA after 60min. During laboratory trials,75% larvae had accepted the MEC-N capsule. The results of the study suggest that chitosan can be used as a wall material for preparing microcapsules to deliver drugs and nutrients to M. rosenbergii larvae.

Comparative efficacy of MS-222 and benzocaine as anaesthetics under simulated transport conditions of a tropical ornamental fish Puntius filamentosus(Valenciennes)

There is a growing commercial interest in the ¢sh, Puntius ¢lamentosus, in the ornamental ¢sh trade in India and elsewhere.The trade is, however, hampered by severe mortalities during transport of the ¢sh owing to insu⁄cient data available on the use of anaesthetics. To resolve this problem, we evaluated the e⁄cacy of two anaesthetics, MS-222 and benzocaine, in sedating P. ¢lamentosus in simulated transportation experiments and used stress response parameters such as cortisol and blood glucose levels to perform assessments. We observed that MS-222 at 40 mg L 1 and benzocaine at 20mg L 1 were su⁄- cient to induce sedation for 48 h. Above these concentrations, both the anaesthetics adversely a¡ected the ¢sh and resulted inmortalities. Both anaesthetics signi¢cantly lowered the blood cortisol and glucose levels compared with the unsedated controls. Importantly, the anaesthetics treatment signi¢cantly lowered the post-transport mortality in the ¢sh. The results of the study show that MS-222 and benzocaine could be used as sedatives to alleviate transport- related stress in P. ¢lamentosus to improve their post-transport survival and hence reduce economic loss.

Growth rate differences between four Chilean populations of edible seaweed Chondracanthus chamissoi (Rhodophyta, Gigartinales)

The effects of temperature, photon flux density and photoperiod on the growth rate of female gametophytic and tetrasporophytic thalli of Chondracanthus chamissoi from four populations along the Chilean coast were studied in vitro. Both reproductive phases survived and grew under all the conditions tested, with growth rates varying between 0.1 and 7.5% day(-1). The results showed higher growth rates with increases in temperature and photon flux density levels. The growth rate was higher in female gametophytic thalli in almost all treatments. The photoperiod did not cause significant differences in the growth rate for either reproductive phases in any of the populations studied. Temperature was the principal factor affecting the growth rate of C. chamissoi.

Salt as a stress response mitigator of matrinxa, Brycon cephalus (Gunther), during transport

The present study evaluated the physiological responses of matrinxa, Brycon cephalus (Gunther), submitted to transport stress under the influence of sodium chloride, Different salt concentrations (0.0%, 0.1%, 0.3% and 0.6%) were added to four 200-L plastic tanks. Each tank was stocked with 30 fish (mean weight 1.0 +/- 0.2 kg) and transported for 4 h. Blood was sampled prior to transport and immediately after and 24 and 96 h after transport. Plasma cortisol and glucose and serum sodium and potassium, plasma chloride and ammonia were analysed, Changes in plasma cortisol were observed immediately after transportation, except in fish transported in 0.3% and 0.6% salt. Twenty-four hours later, this hormone had returned to its initial level in all fish. Blood glucose was not changed in fish treated with 0.6% salt immediately after transport, and returned to the initial level within 96 h after the other treatments. All treatments resulted in lower levels of plasma chloride after transport, except for fish treated with 0.6% salt, with fish treated with 0.0% and 0.3% salt recovering 24 h later, Serum sodium decreased immediately after transport only in the control fish, returning to the initial level 24 h later, the results indicate that treatment with 0.6% NaCl reduces most of the physiological responses of matrinxa to the stress of transport.

Growth performance and energetic metabolism of pacu, Piaractus mesopotamicus (Holmberg, 1887), fed diets supplemented with ammonium metavanadate

Vanadium compounds mimic most of the metabolic effects of insulin, suggesting that it might be useful to improve utilization of dietary carbohydrate. This work evaluated the effect of dietary ammonium metavanadate (H(4)NO(3)V) on the growth performance and energy metabolism of pacu, an omnivorous South America characin. Two hundred and eighty-eight fish were distributed into four blocks according to the body weight (21.8 +/- 1.7, 28.5 +/- 2.0, 28.4 +/- 1.9, 35.7 +/- 1.9 g), stocked in 24 plastic tanks and fed twice daily with isonitrogenous and isoenergetic diets containing six levels of H(4)NO(3)V (0, 10, 50, 100, 300 and 1000 mg kg(-1)) for 60 days. Increasing levels of dietary ammonium metavanadate did not improve growth (P > 0.05), and the highest level of inclusion (1000 mg kg(-1)) reduced performance (P < 0.05). Blood glucose levels decreased (P < 0.05) in fish fed 300 and 1000 mg kg(-1) H(4)NO(3)V, but no differences were observed in other blood metabolites. A slight increase in muscle lipid content was observed in fish fed a diet containing 300 mg kg(-1) H(4)NO(3)V. Based on the results of this study, there is no benefit in supplementing pacu diets with metavanadate.

Limnology of Macrobrachium amazonicum grow-out ponds subject to high inflow of nutrient-rich water and different stocking and harvest management

We evaluated the water characteristics and particle sedimentation in Macrobrachium amazonicum (Heller 1862) grow-out ponds supplied with a high inflow of nutrient-rich water. Prawns were subject to different stocking and harvesting strategies: upper-graded juveniles, lower-graded juveniles, non-graded juveniles + selective harvesting and traditional farming (non-grading juveniles and total harvest only). Dissolved oxygen, afternoon N-ammonia and N-nitrate and soluble orthophosphate were lower in the ponds in comparison with inflow water through the rearing cycle. Ponds stocked with the upper population fraction of graded prawns showed higher turbidity, total suspended solids and total Kjeldahl nitrogen than the remaining treatments. An increase in the chemical oxygen demand:biochemical oxygen demand ratio from inlet (4.9) to pond (7.1-8.0) waters indicated a non-readily biodegradable fraction enhancement in ponds. The sedimentation mean rate ranged from 0.08 to 0.16 mm day(-1) and sediment contained >80% of organic matter. The major factors affecting pond ecosystem dynamic were the organic load (due to primary production and feed addition) and bioturbation caused by stocking larger animals. Data suggest that M. amazonicum grow-out in ponds subjected to a high inflow of nutrient-rich water produce changes in the water properties, huge accumulation of organic sediment at the pond bottom and non-readily biodegradable material in the water column. However, the water quality remains suitable for aquaculture purposes. Therefore, nutrient-rich waters, when available, may represent a source of unpaid nutrients, which may be incorporated into economically valued biomass if managed properly.

Haematologic and immunologic parameters of bullfrogs, Lithobates catesbeianus, fed probiotics

The effects of two probiotics (P(1) - Lactobacillus acidophilus, Bifidobacterium bifidum and Enterococcus faecium and P(2) - Bacillus subtilis) supplemented to commercial feed (40% crude protein) on the haematological and immunological parameters of the bullfrog Lithobates catesbeianus were studied. Two doses of each probiotic (5 and 10 g kg-1 of food) were added to the diets and fed to frogs, totalling five treatments over 112 days. Haematological analyses consisted of total and differential leucocyte counts, erythrocyte and thrombocyte counts, haematocrit, haemoglobin levels and RBC indices (mean corpuscular volume, mean corpuscular haemoglobin - and mean corpuscular haemoglobin concentration) and the immunological parameters included phagocytic capacity and phagocytic index of peritoneal phagocytes. The results showed that the probiotics did not significantly influence any of the haematological parameters measured. However, immunological assays showed that the probiotics had an immunostimulating effect. The greatest effects were seen with probiotic P(1) fed at a dose of 10 g kg-1 of diet and probiotic P(2) fed at 5 g kg-1 of diet.

Effect of polyunsaturated fatty acids on the fecundity of the Amazon river prawn Macrobrachium amazonicum (Heller, 1862)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Spermatozoon ultrastructure and sperm cryopreservation of the Brazilian dry season spawner fish pirapitinga, Brycon nattereri

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)