Survival and changes in the fine structure of selected tissues of Penaeus monodon Fabricius juveniles fed various carbohydrates

Penaeus monodon juveniles were reared on semipurified diets containing various carbohydrates (maltose, sucrose, dextrin, molasses, cassava starch, corn starch or sago palm starch). Significant differences were observed between the type as well as the level of carbohydrate in the diet on the survival of the juveniles. Results indicate that there does not seem to be any correlation between survival and the complexity of the carbohydrates

Evidence-Based Annotation of Gene Function in Shewanella oneidensis MR-1 Using Genome-Wide Fitness Profiling across 121 Conditions

Most genes in bacteria are experimentally uncharacterized and cannot be annotated with a specific function. Given the great diversity of bacteria and the ease of genome sequencing, high-throughput approaches to identify gene function experimentally are needed. Here, we use pools of tagged transposon mutants in the metal-reducing bacterium Shewanella oneidensis MR-1 to probe the mutant fitness of 3,355 genes in 121 diverse conditions including different growth substrates, alternative electron acceptors, stresses, and motility. We find that 2,350 genes have a pattern of fitness that is significantly different from random and 1,230 of these genes (37% of our total assayed genes) have enough signal to show strong biological correlations. We find that genes in all functional categories have phenotypes, including hundreds of hypotheticals, and that potentially redundant genes (over 50% amino acid identity to another gene in the genome) are also likely to have distinct phenotypes. Using fitness patterns, we were able to propose specific molecular functions for 40 genes or operons that lacked specific annotations or had incomplete annotations. In one example, we demonstrate that the previously hypothetical gene SO_3749 encodes a functional acetylornithine deacetylase, thus filling a missing step in S. oneidensis metabolism. Additionally, we demonstrate that the orphan histidine kinase SO_2742 and orphan response regulator SO_2648 form a signal transduction pathway that activates expression of acetyl-CoA synthase and is required for S. oneidensis to grow on acetate as a carbon source. Lastly, we demonstrate that gene expression and mutant fitness are poorly correlated and that mutant fitness generates more confident predictions of gene function than does gene expression. The approach described here can be applied generally to create large-scale gene-phenotype maps for evidence-based annotation of gene function in prokaryotes

Genetic Basis of Myocarditis: Myth or Reality?

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Changes induced in the gills of milkfish (Chanos chanos Forsskål) fingerlings after acute exposure to nifurpirinol (Furanace; P-7138)

The need for a chemotherapeutant used specifically for fish disease became increasingly apparent with intensive fish culture practices, and with the possibility of bacterial resistance against drugs used for human and animal medicine (Austin 1985). With this in mind, Nifurpirinol (trade name Furanace; P-7138) was developed by the Dainippon Pharmaceutical Co., Ltd., Japan, and is currently manufactured in the United States as Prefuran. Studies have proven that the drug is effective against bacterial and fungal pathogens in a wide variety of aquatic animals. Most of the Nifurpirinol studies done in the past have dealt on its antimicrobial activity, tissue uptake, and effective treatment levels ranging from 0.5-2.5 mg/L. The 96-hr median lethal concentration (LC50) to channel catfish (Ictalurus punctatus Rafinesque) has also been determined at 0.945-1.90 mg/L, and at 1.70 mg/L for milkfish, Chanos chanos Forsskaal. However, there have only been two studies that have examined the histological effects on treated fish. Histopathologically, Mitchell et al. (1978) found hypertrophy and hyperplasia of the lamellar epithelium in channel catfish gills exposed to 0.5 mg/L for 4 d or longer at 24 plus or minus 2 degree C, while Amend and Ross (1970) working at 21 plus or minus 1 degree C observed no apparent changes in the gills of coho salmon (Oncorhynchus kisutch) exposed intermittently to 1 mg/L of Nifurpirinol. This paper describes the histological changes observed in the gills of milkfish fingerlings used in static, 96-hr Nifurpirinol toxicity tests. Milkfish was used because of its economic importance as a widely cultured food fish in Asia. The gills were chosen as target organs

Histopathological response of milkfish Chanos chanos Forsskal fingerlings to potassium permanganate

Static 96 h bioassays were conducted on milkfish fingerlings at concentrations ranging from 1.00 to 1.80 mg/l KMnO4. Histopathological analyses of gills, liver, and kidney tissues revealed significant changes even in non-lethal concentrations tested. Damage became severe with increasing concentration and longer exposure to the chemical. Partial to complete recovery was observed in gills, liver, and kidney cells of fish exposed to KMnO4 for 96 h and then maintained in KMnO4-free seawater for 240 h

Acute toxicity of nifurpirinol, a fish chemotherapeutant, to milkfish (Chanos chanos) fingerlings

Nifurpirinol (trade name Furanace and originally known as P-7138), is a nitrofuran derivative synthesized by the Dainippon Pharmaceutical Co. Ltd., Japan, and was developed exclusively as a broad-spectrum antibiotic for fish and other aquatic organisms (Shimizu and Takase 1967). It has been shown to have bactericidal and fungicidal action in vitro and in vivo (Shimizu and Takase 1967; Amend and Ross 1970; Pearse et al. 1974; Mitchell and Plumb 1980), and was used because of its excellent potential in controlling prawn diseases (Delves-Broughton 1974; Gacutan and Llobrera 1977). Milkfish (Chanos chanos Forsskal) is a widely-reared species and a very important aquaculture food crop in most parts of Southeast Asia. Thus, it was the logical choice as test animal for investigating the LC50 toxicity levels of nifurpirinol (6-hydroxymethyl-2-[2-(5-nitro-2-furyl) vinyl] pyridine) after 96 hr exposure. Changes in the normal gill architecture of milkfish after exposure to the drug were also studied (Tamse et al., in preparation)

Induction of metamorphosis in Hermissenda crassicornis larvae (Mollusca: Nudibranchia) by GABA, choline and serotonin

The nudibranch mollusc Hermissenda crassicornis is currently used as a biomedical model in neurobiological studies. It possesses planktotrophic larvae which metamorphose in the laboratory in the presence of the hydroid Tubularia crocea in yields of about 2–5% (Tamse et al., 1990). This study presents evidence that artificial metamorphic inducers such as GABA (γ-aminobutyric acid), choline, and serotonin (alone or combined with the natural inducer T. crocea), can be used to improve the metamorphic success in H. crassicornis larvae. GABA at 10−5M and 10−4M, choline at 10−3M and 10−4M, and serotonin at 10−5 M and 10−4M, were most effective, while serotonin at 10−3 M was toxic. Larvae 47 and 63 days old metamorphosed at different rates when exposed to the same concentrations of chemicals, but these had no positive effect on young larvae, i.e., 28 and 39 days old. On the other hand, when young larvae were exposed to the natural inducer, an habituation phenomenon was observed, i.e., the larvae did not metamorphose. Exposing the larvae to the natural inducer after larval day 47 improved the metamorphic yield by about 100%. These results indicate that the optimum larval age for inducing metamorphosis in H. crassicornis is older than previously considered.Peer reviewe

Survival and some histological changes in Penaeus monodon Fabricius juveniles fed various carbohydrates

SEAFDEC Aquaculture Department Contribution No. 97.Juveniles of P. monodon Fabricius (initial mean weight 1.76 g) were reared on semipurified diets containing 10 or 40% maltose, sucrose, dextrin, molasses, cassava starch, corn starch or sago palm starch for 6 weeks. Highest survival (56%) was obtained in juveniles fed with a diet containing 10% sucrose. Within 10 days of rearing, complete mortality was observed in prawns fed with higher levels of maltose and molasses. After 6 weeks, among the starches, sago palm starch provided for the best survival at 10% level. There was no relationship between time to death and size of the prawn (r = −0.10). Significant differences were observed between the type, as well as the level, of carbohydrate in the diet on the survival of juvenile prawn. Histopathological changes in the hepatopancreas, gills and exoskeleton of juveniles fed with the various carbohydrates were also studied

Biological factors affecting larval growth in the nudibranch mollusc Hermissenda crassicornis (Eschscholtz, 1831)

The nudibranch mollusc Hermissenda crassicornis is used as a biomedical model for studying learning and memory. It is an eurytrophic benthic species with long-term, planktotrophic larvae, and it has been cultured in our laboratory for several years. This paper reports the effects of some dietary factors on H. crassicornis larvae that were investigated in order to establish the conditions 21 for optimal larval growth. Of the several treatments tested, densities of 1–4 larvae ml , a diet of Isochrysis galbana Parke and Rhodomonas salina (Wislouch) Butcher at a 1:1 mixture, and an 3 21 algal density of 10–25 3 10 cells ml yielded the largest, healthiest larvae, that underwent metamorphosis. Both diet quantity and quality, as well as larval density, had an effect on larval growth and metamorphosis of Hermissenda crassicornis in the laboratory. 1997 Elsevier Science B.V.Peer reviewe