Characterization and cytotoxicity of low-molecular-weight chitosan and chito-oligosaccharides derived from tilapia fish scales.

The present study evaluated the physicochemical characterization and cytotoxicity activity of chitosan and chito-oligosaccharides (COSs). The extraction of chitosan and COSs was executed by chemical hydrolysis. The physicochemical characterization and deacetylation (DA) value were determined using an FTIR. The molecular weight was determined by using the Mark-Houwink equation. The physical parameters such as solubility, water-binding capacity (WBC), and fat-binding capacity (FBC) were determination as per equation (i), (ii), and (iii) respectively. The cytotoxic activities of chitosan and COS against MCF-7, HepG2, HeLa-6, and 3T3 were performed by MTS assay. The COS induced enhance cytotoxicity with IC50 0.87 and2.21 mg/ml against MCF-7 and HepG2 respectively. However, COSs seem to be more sensitive toward the cell lines with the relative potential of MCF-7 > HepG2 > HeLa. Hence, the results showed promising future perspectives of chitosan and COS to develop biodegradable, antibacterial, cytotoxic naturally derived polysaccharides for cancer drug delivery and smart wound dressings.

Histochemical distribution of four types of enzymes and mucous cells in the gastrointestinal tract of reared half-smooth tongue sole Cynoglossus semilaevis.

The histochemical distribution of acid phosphatase (ACP), alkaline phosphatase (ALP), non-specific esterase (NSE), peroxidase (POD) and mucous-cell types was evaluated in the gastrointestinal tract of the half-smooth tongue sole Cynoglossus semilaevis. The enzymes were detected in the entire stretch of the gastrointestinal tract. ACP activity was found in the supranuclear region of enterocytes and the lamina propria of the intestine, as well as the cytoplasm of epithelial cells of the stomach. The staining intensity of ACP in the anterior and posterior intestines was stronger than in the stomach. ALP activity was detected in the striated border of enterocytes and muscularis of the whole intestine, lamina propria and supranuclear cytoplasm of the enterocytes in the anterior intestine, as well as in the blood vessels of the stomach. The staining intensity for ALP in the anterior intestine was stronger than in the posterior segment and the latter was stronger than in the stomach. NSE activity was detected in the cytoplasm of the epithelial cells in the entire gastrointestinal tract, with the anterior intestine showing stronger intensity than the stomach. POD activity was located in the blood cells of the lamina propria of the gastrointestinal tract and the levels in the stomach were similar to the anterior and posterior intestines. Alcian blue (pH 2·5) periodic acid Schiff (AB-PAS) histochemical results revealed three types of mucous cells in the gastrointestinal tract. Type I cells (PAS+AB-) were observed among the gastric mucosa columnar cells in the stomach and enterocytes in the basal region of the villi and in the middle and top regions of the intestinal villi. Type II cells (PAS-AB+) and type III cells (PAS+AB+) were not detected in the stomach but were distributed ubiquitously among enterocytes in the middle and top regions of the intestinal villi.

Ingestion of food pellets containing Escherichia coli overexpressing the heat-shock protein DnaK protects Penaeus vannamei (Boone) against Vibrio harveyi (Baumann) infection.

Feeding aquatic animals with bacterial encapsulated heat-shock proteins (Hsps) is potentially a new method to combat vibriosis, an important disease affecting aquatic animals used in aquaculture. Food pellets comprised of shrimp and containing Escherichia coli overexpressing either DnaK-DnaJ-GrpE, the prokaryotic equivalents of Hsp70-Hsp40-Hsp20, or only DnaK were fed to juveniles of the white leg shrimp Penaeus vannamei, and protection against pathogenic Vibrio harveyi was determined. Maintaining pellets at different temperatures for varying lengths of time reduced the number of live adhering E. coli, as did contact with sea water, demonstrating that storage and immersion adversely affected bacterial survival and attachment to pellets. Feeding P. vannamei with E. coli did not compromise their survival, indicating that the bacteria were not pathogenic to shrimp. Feeding P. vannamei with pellets containing bacteria overproducing DnaK (approximately 60 cells g(-1) pellets) boosted P. vannamei survival twofold against V. harveyi, suggesting that DnaK plays a role in Vibrio tolerance. Pellets containing DnaK were effective in providing protection to P. vannamei for up to 2 weeks before loss of viability and that DnaK encapsulated by these bacteria enhanced shrimp resistance against Vibrio infection.

Enhancement of Hsp70 synthesis protects common carp, Cyprinus carpio L., against lethal ammonia toxicity.

Exposure to TEX-OE®, a patented extract of the prickly pear cactus (Opuntia ficus indica) containing chaperone-stimulating factor, was shown to protect common carp, Cyprinus carpio L., fingerlings against acute ammonia stress. Survival was enhanced twofold from 50% to 95% after exposure to 5.92 mg L(-1) NH(3) , a level determined in the ammonia challenge bioassay as the 1-h LD50 concentration for this species. Survival of TEX-OE®-pre-exposed fish was enhanced by 20% over non-exposed controls during lethal ammonia challenge (14.21 mg L(-1) NH(3) ). Increase in the levels of gill and muscle Hsp70 was evident in TEX-OE®-pre-exposed fish but not in the unexposed controls, indicating that application of TEX-OE® accelerated carp endogenous Hsp70 synthesis during ammonia perturbation. Protection against ammonia was correlated with Hsp70 accretion.

Obesity of TallyHO/JngJ mouse is due to increased food intake with early development of leptin resistance.

TALLYHO/JngJ (TallyHo) mouse is a recently established animal model for type 2 diabetes mellitus (T2DM) with phenotypes of mild obesity and male-limited hyperglycemia. In this study, we investigated how obesity develops in TallyHo mice by measuring parameters of food intake and energy expenditure. At 4 weeks of age, TallyHo mice were heavier than control C57BL/6 mice with increased food intake but comparable energy expenditure parameters, such as body temperature, cold-induced thermogenesis, oxygen consumption rate (VO(2)) and spontaneous locomotor activity. Furthermore, pair-fed TallyHo mice, which were fed the same amount of food as C57BL/6 mice, showed similar patterns of body weight gain to C57BL/6 mice at all ages, implying that obesity in TallyHo mice may develop by increased food intake but not by decreased energy consumption. TallyHo mice appear to have hypothalamic leptin resistance at 4 weeks of age, as indicated by the increased expression of orexigenic neuropeptides in the hypothalamus and no alteration of food intake and neuropeptide expression upon intravenous leptin treatment. Leptin injection to TallyHo mice, however, increased the phosphorylation of STAT3 and Akt, an important signaling mediator of leptin, in a pattern similar to that in C57BL/6 mice. In conclusion, increased food intake is a crucial component in the development of obesity in TallyHo mice, in which central leptin resistance, possibly caused by uncoupling between activation of leptin signaling and neuropeptide expression, might be involved.

Heat shock proteins (chaperones) in fish and shellfish and their potential role in relation to fish health: a review.

Heat shock proteins (HSPs), also known as stress proteins and extrinsic chaperones, are a suite of highly conserved proteins of varying molecular weight (c. 16-100 kDa) produced in all cellular organisms when they are exposed to stress. They develop following up-regulation of specific genes, whose transcription is mediated by the interaction of heat shock factors with heat shock elements in gene promoter regions. HSPs function as helper molecules or chaperones for all protein and lipid metabolic activities of the cell, and it is now recognized that the up-regulation in response to stress is universal to all cells and not restricted to heat stress. Thus, other stressors such as anoxia, ischaemia, toxins, protein degradation, hypoxia, acidosis and microbial damage will also lead to their up-regulation. They play a fundamental role in the regulation of normal protein synthesis within the cell. HSP families, such as HSP90 and HSP70, are critical to the folding and assembly of other cellular proteins and are also involved in regulation of kinetic partitioning between folding, translocation and aggregation within the cell. HSPs also have a wider role in relation to the function of the immune system, apoptosis and various facets of the inflammatory process. In aquatic animals, they have been shown to play an important role in health, in relation to the host response to environmental pollutants, to food toxins and in particular in the development of inflammation and the specific and non-specific immune responses to bacterial and viral infections in both finfish and shrimp. With the recent development of non-traumatic methods for enhancing HSP levels in fish and shrimp populations via heat, via provision of exogenous HSPs or by oral or water administration of HSP stimulants, they have also, in addition to the health effects, been demonstrated to be valuable in contributing to reducing trauma and physical stress in relation to husbandry events such as transportation and vaccination.

Feeding Artemia franciscana (Kellogg) larvae with bacterial heat shock protein, protects from Vibrio campbellii infection.

Among their numerous physiological effects, heat shock proteins (Hsps) are potent immunomodulators, a characteristic reflecting their potential as therapeutic agents and which led to their application in combating infection. As an example, the up-regulation of endogenous Hsp70 in the branchiopod crustacean Artemia franciscana (Kellogg) is concurrent with shielding against bacterial infection. To better understand this protective mechanism, gnotobiotic Artemia were fed with Escherichia coli treated to over-produce different prokaryotic Hsps. This was shown to increase larval resistance to experimental Vibrio campbellii exposure. Immunoprobing of Western blots showed that the enhanced resistance to V. campbellii correlated with DnaK production in E coli. A definitive role for DnaK was then demonstrated by feeding Artemia larvae with transformed bacteria over-producing only this protein, although other Hsps such as DnaJ and grpE also provided tolerance against Vibrio infection. Feeding of bacteria synthesizing selected Hsps is therefore suggested as an alternative to antibiotic use as a means of enhancing resistance of Artemia larvae to bacterial infection, which may have potential applications in aquaculture.

Mice immunized with DNA encoding a modified Pseudomonas aeruginosa exotoxin A develop protective immunity against exotoxin intoxication.

A recombinant plasmid, which contains the Pseudomonas aeruginosa exotoxin A (PE) gene with a C-terminal deletion, was inserted into expression vector pSecTag Xpress. The expression of this bacterial exotoxin in an animal cell was first demonstrated in 3T3 cell by transient transfection and western blot assay. Recombinant plasmid DNA was then injected intramuscularly to BALB/c mice, anti-PE specific antibodies were found in all animals vaccinated with plasmid containing the PE gene and with 'detoxicated' recombinant PE protein. Mice vaccinated with DNA were protected from the intoxication of lethal dosage of P. aeruginosa exotoxin A. Our results indicated that mice vaccinated with DNA encoding the PE gene could express PE protein in vivo, induced specific immune response, and provided sufficient protective immunity that safeguarded mice from the injection of lethal dosage of PE toxin.

Cytogenetical analysis of the germ cell in the domestic drake and mule drake.

Experiments were conducted to study the germ cell of testes in the domestic drake (Tsaiya drake) and the mule drake. The histological sections of testes of both drakes were compared in this study. The results showed that rapid testicular growth did not occur until 7 weeks of age in domestic drakes and 15 weeks of age in the mule drakes. The rate of growth of the testes and the increase in the ratio of testes weight to body weight in domestic drakes at different ages were much more rapid than in the mule drakes. However, the opposite results were found in the body weights. In the mule drakes, spermatogonia and primary spermatocytes could be observed in the seminiferous tubules, but no secondary spermatocytes, spermatids or spermatozoa in seminiferous tubules were found up to 52 weeks of age. This showed that the meiotic division had not occurred in the mule drakes. In the domestic drakes, spermatogonia in the seminiferous tubules were observed at 1 week of age. Primary spermatocytes of some males appeared as early as the third week of age. Secondary spermatocytes and spermatids in the seminiferous tubules of some drakes began to appear at 5 weeks of age as a result of the meiotic division of the spermatocytes. At 7 weeks of age, spermatids were in process of metamorphosis, and spermatozoa were first observed in the seminiferous tubules of the drake. All testes of drakes 9 weeks of age contained spermatozoa. The percentage of the seminiferous tubules containing spermatozoa increased gradually with age, and approached a plateau at 15 weeks of age.(ABSTRACT TRUNCATED AT 250 WORDS)