Maximum prey size estimation of longtooth grouper,Epinephelus bruneus,using morphological features,and predation experiments on juvenile cannibalism

In fish culture, cannibalism, which induces critical damage, is separated into two types: type I, which occurs in early larval stages when size heterogeneity is low; and type II, which starts in later larval and/or early juvenile stages following type I when size heterogeneity is high. In type II, the cannibal's maximum prey size is limited by its gape size relative to the prey fish body size. Ratios of prey to cannibal body size changes are associated with allometric factors and feeding behaviour with growth. In a previous study on grouper, the maximal prey size was estimated morphologically (i.e., the relationship between gape size and body height). This method is very simple and useful; however, it does not consider allometric factors and feeding behaviour changes; therefore, it probably causes a large estimation error. To overcome this, we present a new method for estimating maximal prey size to determine the size ranges for size grading of longtooth grouper, Epinephelus bruneus, juveniles using predation experiments. It is shown that grouper type II cannibalism is affected by two factors; in early juvenile stages by morphology and in later (TL over 50 mm) by prey size selectivity.     

Epigenetic assessment of environmental chemicals detected in maternal peripheral and cord blood samples

Epigenetic alteration is an emerging paradigm underlying the long-term effects of chemicals on gene functions. Various chemicals, including organophosphate insecticides and heavy metals, have been detected in the human fetal environment. Epigenetics by DNA methylation and histone modifications, through dynamic chromatin remodeling, is a mechanism for genome stability and gene functions. To investigate whether such environmental chemicals may cause epigenetic alterations, we studied the effects of selected chemicals on morphological changes in heterochromatin and DNA methylation status in mouse ES cells (ESCs). Twenty-five chemicals, including organophosphate insecticides, heavy metals and their metabolites, were assessed for their effect on the epigenetic status of mouse ESCs by monitoring heterochromatin stained with 4￠,6-diamino-2-phenylindole (DAPI). The cells were surveyed after 48 or 96 h of exposure to the chemicals at the serum concentrations of cord blood. The candidates for epigenetic mutagens were examined for the effect on DNA methylation at genic regions. Of the 25 chemicals, five chemicals (diethyl phosphate (DEP), mercury (Hg), cotinine, selenium (Se) and octachlorodipropyl ether (S-421)) caused alterations in nuclear staining, suggesting that they affected heterochromatin conditions. Hg and Se caused aberrant DNA methylation at gene loci. Furthermore, DEP at 0.1 ppb caused irreversible heterochromatin changes in ESCs, and DEP-, Hg- and S-421-exposed cells also exhibited impaired formation of the embryoid body (EB), which is an in vitro model for early embryos. We established a system for assessment of epigenetic mutagens. We identified environmental chemicals that could have effects on the human fetus epigenetic status.     

Effect of silicon on alleviation of manganese toxicity in pumpkin (Cucurbita moschata Duch cv. Shintosa)

A series of experiments was conducted to investigate the mechanism of Siinduced alleviation of Mn toxicity in pumpkin (Cucurbita moschata Duch cv. Shintosa) which has been used as a bloom-type stock for grafting cultivation of cucumbers. In the first experiment, the effect of Si on Mn toxicity in the Shintosa cultivar was compared with that in the Super unryu cultivar which is used as a bloomless-type stock. Without Si supply, growth depression occurred in both cultivars at the levels of 100 and 500 µM Mn in the nutrient solution. The alleviative effect of Si on the growth depression was observed more distinctly for the Shintosa cultivar than for the Super unryu cultivar, and the effect became more pronounced with increasing Si levels in the nutrient solution. Regardless of the Mn levels, addition of Si did not decrease the Mn content of the plants. The relative shoot growth was reduced to less than 80% when the molar ratio of Si/Mn in the shoots was lower than 4.5. In the second experiment, Mn and Si in the lower leaves of the Shintosa cultivar treated with different levels of Mn with and without Si supply were extracted with 10 mM Tris-HCI buffer (pH 7.4). At the levels of 100 and 250 µM Mn, the amounts of Mn in the buffer-insoluble fraction increased in the presence of Si supply and the buffer-soluble Mn accounted for less than 9% of the total Mn in the leaf. In addition, more than 84% of the total Si was found in the buffer-insoluble fraction at each Mn level. Distribution of Mn and Si on the surface of the lowerú leaves of the Shintosa cultivar treated with 250 µM Mn with and without Si supply was examined by electron probe X-ray microanalysis in the third experiment; Both Mn and Si accumulated at high concentrations around the base of the trichomes in the presence of Si supply. Without Si supply, Mn was detected around the necrotic brown lesions in addition to the base of the trichomes. These results suggested that in the Shintosa cultivar, Si alleviated the Mn toxicity through a localized accumulation of Mn with Si in a metabolically inactive form around the base of the trichomes on the leaf surface.     

Adsorption,desorption and dissipation of metolachlor in surface and subsurface soils

BACKGROUND: Variations in soil properties with depth influence retention and degradation of pesticides. Understanding how soil properties within a profile affect pesticide retention and degradation will result in more accurate prediction by simulation models of pesticide fate and potential groundwater contamination. Metolachlor is more persistent than other acetanilide herbicides in the soil environment and has the potential to leach into groundwater. Reasonably, information is needed about the dissipation and eventual fate of metolachlor in subsoils. The objectives were to evaluate the adsorption and desorption characteristics and to determine the dissipation rates of metolachlor in both surface and subsurface soil samples. RESULTS: Adsorption of metolachlor was greater in the high‐organic‐matter surface soil than in subsoils. Lower adsorption distribution coefficient (K_ads) values with increasing depth indicated less adsorption at lower depths and greater leaching potential of metolachlor after passage through the surface horizon. Desorption of metolachlor showed hysteresis, indicated by the higher adsorption slope (1/n_ads) compared with the desorption slope (1/n_des). Soils that adsorbed more metolachlor also desorbed less metolachlor. Metolachlor dissipation rates generally decreased with increasing soil depth. The first‐order dissipation rate was highest at the 0–50 cm depth (0.140 week^?1) and lowest at the 350–425 cm depth (0.005 week^?1). Degradation of the herbicide was significantly correlated with microbial activity in soils. CONCLUSION: Metolachlor that has escaped degradation or binding to organic matter at the soil surface might leach into the subsurface soil where it will dissipate slowly and be subject to transport to groundwater. Copyright © 2009 Society of Chemical Industry     

Effects of Nitrogen Forms on Carbon and Nitrogen Accumulation in Tomato Seedling

Utilization of organic nitrogen （N） is an important aspect of plant N assimilation and has potential application in sustainable agriculture. The aim of this study was to investigate the plant growth, C and N accumulation in leaves and roots of tomato seedlings in response to inorganic （NH4^＋-N, NO3^-N） and organic nitrogen （Gly-N）. Different forms of nitrogen （NH4^＋-N, NO3^--N, Gly-N） were supplied to two tomato cultivars （Shenfen 918 and Huying 932） using a hydroponics system. The plant dry biomass, chlorophyll content, root activity, total carbon and nitrogen content in roots and leaves, and total N absorption, etc. were assayed during the cultivation. Our results showed that no significant differences in plant height, dry biomass, and total N content were found within the first 16 d among three treatments; however, significant differences in treatments on 24 d and 32 d were observed, and the order was NO3^--N 〉 Gly-N 〉 NH4^＋-N. Significant differences were also observed between the two tomato cultivars. Chlorophyll contents in the two cultivars were significantly increased by the Gly-N treatment, and root activity showed a significant decrease in NHa^＋-N treatment. Tomato leaf total carbon content was slightly affected by different N forms; however, total carbon in root and total nitrogen in root and leaf were promoted significantly by inorganic and organic N. Among the applied N forms, the increasing effects of the NH4^＋-N treatment were larger than that of the Gly-N. In a word, different N resources resulted in different physiological effects in tomatoes. Organic nitrogen （e.g., Gly-N） can be a proper resource of plant N nutrition. Tomatoes of different genotypes had different responses under organic nitrogen （e.g., Gly-N） supplies.     

Efficacy of omeprazole paste in the prevention of gastric ulcers in 2 years old thoroughbreds

Prevalence of equine gastric ulcer syndrome in 85 young Thoroughbreds was investigated. The presence of gastric ulcers was confirmed in 27.1% (23/85) of the horses by endoscopic examination. Sixty-two horses without gastric ulcers were allocated randomly to either the treated group (31 horses) or sham-dosed control group (31 horses) in order to investigate the efficacy of omeprazole oral paste in the prevention of gastric ulcers. At the second endoscopic examination conducted after 28 days of administration, only 1 horse in the treated group developed gastric ulcers, while 12 horses developed gastric ulcers in the control group. Based on these data, the efficacy of omeprazole in prevention of equine gastric ulcers in young Thoroughbreds during the training period was confirmed.     

Decreased gene expression of insulin signaling genes in insulin sensitive tissues of obese cats

Type 2 diabetes mellitus (DM) animal models have provided ample opportunity for investigating pathogenesis, as well as to evaluate novel treatment and prevention options for the disease. Because the domestic cat shares a similar environment with humans, it is also confronted with many similar risk factors for diabetes, such as physical inactivity and obesity. Obesity is a significant risk factor for diabetes in cats, and as such, the domestic cat may serve as an ideal model for investigating obesity induced insulin resistance. This study determined changes in insulin signaling genes within insulin sensitive tissues of obese felines. Quantitative RT-PCR was performed to determine mRNA levels of three important insulin signaling genes which have been implicated with insulin resistance: insulin receptor substrate (IRS)-1, IRS-2, and phosphatidylinositol 3’-kinase (PI3-K) p85α. Obese cats had significantly lower IRS-2 and PI3-K p85α mRNA levels in liver and skeletal muscle as compared to control cats. This down regulation of insulin signaling genes in obese cats mirrors that of obese humans and rodents suffering from insulin resistance. Interestingly, preprandial blood tests indicated that our obese cats were no different from control cats with regards to glucose tolerance and insulin resistance, thus indicating that the obese cats used in our study had a moderate level of obesity. Therefore, insulin signaling gene alterations were occurring in insulin sensitive tissues of moderately obese felines before glucose intolerance was clinically evident. As such, the monitoring of key insulin signaling genes may have some important diagnostic value to determine the risk level and degree of obesity induced insulin resistance.     

A canine pemphigus foliaceus case showing parallel relationship of disease activity and titer of serum anti-keratinocyte cell surface antibodies

A seven-year-old, spayed female mongrel dog was diagnosed as pemphigus foliaceus (PF) by clinical, histopathological and immunopathological observations. Serum antibodies against the cell surface of keratinocytes in the dog were detected by indirect immunofluorescence (IIF) using cryosectioned bovine esophagus as well as living cultured-canine keratinocytes as the substrates. When we compared the titers of IIF on bovine esophagus with its disease activity, the IIF titers reflected the disease activity throughout the time course. Our findings will suggest that sequential titration of serum antibodies by IIF will be useful for monitoring the serological disease activity in canine PF.     

Induction of immune responses against glycosphingolipid antigens: comparison of antibody responses in mice immunized with antigen associated with liposomes prepared from various phospholipids

The immune responses of mice against glycosphingolipid (GSL) antigens and the effect of the phospholipid composition of liposomes on the immunogenicity in mice of liposome-associated GSL antigens were examined. The immunization with GSL antigen alone was unable to induce any detectable anti-GSL antibody responses. On the other hand, the immune responses against GSL antigens were detected after immunization with liposomes composed of dipalmitoylphosphatidylcholine (DPPC) (0.5 micromol), cholesterol (Chol) (0.5 micromol), Salmonella minnesota R595 lipopolysaccharides (LPS) (10 microg) and GSL (0.05 micromol) (DPPC-liposome). However, the administration with liposome composed of dimyristoylphosphatidylcholine (DMPC) (0.5 micromol), Chol (0.5 micromol), S. minnesota R595 LPS (10 microg) and GSL (0.05 micromol) and with liposomes composed of distearylphosphatidylcholine (DSPC) (0.5 micromol), Chol (0.5 micromol), and S. minnesota R595 LPS (10 microg) and GSL (0.05 micromol) was ineffective for the induction of the immune responses against GSL antigens. These results suggest that DPPC-liposome would serve effectively as a delivery vehicle for inducing immune responses against GSL antigen.