Acute Toxicity and Neurotoxicity of Chlorpyrifos in Black Tiger Shrimp, Penaeus monodon

Acute toxicity and neurotoxicity of chlorpyrifos were determined in black tiger shrimp, P. monodon. LC50 values after 24 to 96 h of exposure were between 149.55 and 59.16 nmol/L. To determine the neurotoxicity of chlorpyrifos, the inhibition of acetylcholinesterase was monitored in the gill of the shrimps exposed to lethal (0.019, 0.194, and 1.942 µmol/L) and sub-lethal (0.019, 0.194, and 1.942 nmol/L) concentrations of chlorpyrifos. In lethal dose exposure, the AChE activities observed in shrimp exposed to 0.194, and 1.942 µmol/L of chlorpyrifos were significantly lower (1.7 and 3.3 times) than that of control shrimp after 30 min of exposure (p<0.05). In sub-lethal exposure tests, the AChE activity of shrimp was significantly lower (1.9 times) than that of control shrimp after exposure to 1.942 nmol/L of chlorpyrifos for 72 h (p<0.05). The sensitive reduction of AChE activity at the sub-lethal concentration, which was 30 times lower than 96 h LC50 value found in this study, indicates the potential use as a biomarker of chlorpyrifos exposure

Water pollution and habitat degradation in the Gulf of Thailand

The Gulf of Thailand has been a major marine resource for Thai people for a long time. However, recent industrialization and community development have exerted considerable stress on the marine environments and provoked habitat degradation. The following pollution problems in the Gulf have been prioritized and are discussed in details: (1) Untreated municipal and industrial waste water are considered to be the most serious problems of the country due to limited waste water treatment facilities in the area. (2) Eutrophication is an emerging problem in the gulf of Thailand. Fortunately, the major species of phytoplankton that have been reported as the cause of red tide phenomena were non-toxic species such as Noctiluca sp. and Trichodesmium sp. (3) Few problems have been documented from trace metals contamination in the Gulf of Thailand and public health threat from seafood contamination does not appear to be significant yet. (4) Petroleum hydrocarbon residue contamination is not a problem, although a few spills from small oil tankers have been recorded. A rapid decrease in mangrove forest, coral reefs, and fisheries resources due to mismanagement is also discussed

Isolation and characterization of genes functionally involved in ovarian development of the giant tiger shrimp Penaeus monodon by suppression subtractive hybridization (SSH)

Suppression subtractive hybridization (SSH) libraries between cDNA in stages I (previtellogenic) and III (cortical rod) ovaries of the giant tiger shrimp (Penaeus monodon) were established. In all, 452 ESTs were unidirectionally sequenced. Sequence assembly generated 28 contigs and 201 singletons, 109 of which (48.0%) corresponding to known sequences previously deposited in GenBank. Several reproduction-related transcripts were identified. The full-length cDNA of anaphase promoting complex subunit 11 (PmAPC11; 600 bp with an ORF of 255 bp corresponding to a polypeptide of 84 amino acids) and selenoprotein M precursor (PmSePM; 904 bp with an ORF of 396 bp corresponding to a polypeptide of 131 amino acids) were characterized and reported for the first time in penaeid shrimp. Semiquantitative RT-PCR revealed that the expression levels of PmSePM and keratinocyte-associated protein 2 significantly diminished throughout ovarian development, whereas Ser/Thr checkpoint kinase 1 (Chk1), DNA replication licensing factor mcm2 and egalitarian were down-regulated in mature ovaries of wild P. monodon (p < 0.05). Accordingly, the expression profiles of PmSePM and keratinocyte-associated protein 2 could be used as biomarkers for evaluating the degree of reproductive maturation in domesticated P. monodon

Growth promotion and enhancement of vibriosis resistance in penaeid shrimp after oral administration of lactic acid bacteria and marine bacteria

Vibriosis is one of the most serious problems in the shrimp culture industry worldwide. Antibiotic treatment is becoming less and less effective, as new strains of pathogens evolve, which are resistant to commonly used antibiotics. Use of probiotics is an alternative method for controlling bacteria in shrimp culture. In this experiment, lactic acid bacteria (Peddiococcus sp, Lactobacillus sp, and L. acidophilus) and marine bacteria (Alteromonas sp. and Vibrio alginolyticus) were mixed with pellet feed and used to feed juvenile shrimp. The growth and survival rate of the shrimp were monitored during the experiment. After feeding the shrimp for 60 days, all the surviving shrimp were bath-challenged with Vibrio harveyi (105-106 CFU/ml) for 7 days. Mortality of the shrimp was recorded. The result shows that the total biomass and survival rate of the shrimp fed with probiotics were significantly higher than the control group (p<0.05). However, there were no significant differences in the mean growth rate of shrimp between treatments. The results of the challenge test shows that the groups fed with lactic acid bacteria had the highest survival rates (Peddiococcus sp., 86.4%; Lactobacillus sp., 90.5% and L. acidophilus, 93.8%), followed by the treatments fed with marine bacteria (Alteromonas sp, 74.6% and Vibrio alginolyticus, 61.8%) and the control treatment had the lowest survival rate (59%)