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Leaf rust caused by Puccinia triticina is one of the main diseases affecting wheat (Triticum aestivum) production worldwide. Calmodulin (CaM) was found involved in the early stage of signal transduction pathway in response to P. triticina in wheat. To study the function and molecular mechanism of calmodulin (CaM) in signal transduction of wheat against P. triticina, we cloned a putative calmodulin-binding transcription activator (TaCAMTA4), and characterized its molecular structure and functions by using the CaM-encoding gene (TaCaM4-1) as a bait to screen the cDNA library from P. triticina infected wheat leaves. The open reading frame of TaCAMTA4 was 2505 bp encoding a protein of 834 aa, which contained all the four conserved domains of family (CG-1 domain, TIG domain, ANK repeats and CaM-binding domain). TaCaM4-1 bound to TaCAMTA4 by the C-terminal CaM-binding domain in Ca2+-dependent manner in the electrophoretic mobility shift assay (EMSA). Bimolecular fluorescence complementation (BiFC) analysis indicated that the interaction of TaCAMTA4 and TaCaM4-1 took place in the cytoplasm and nucleus of epidermal leaf cells in N. benthamiana. The expression level of TaCAMTA4 genes was down-regulated in incompatible combination after P. triticina infection. Furthermore, virus-induced gene silencing (VIGS)-based knockdown of TaCAMTA4 and disease assays verified that silencing of TaCAMTA4 resulted in enhanced resistance to P. triticina race 165. These results suggested that TaCAMTA4 function as negative regulator of defense response against P. triticina.

Introduction: The purpose of this study was to assess enrichments in stable carbon and nitrogen isotopes (δ 13 C and δ 15 N) in brown-marbled groupers (Epinephelus fuscoguttatus), a marine fish that has been widely used in aquaculture. Stable isotope analysis has been used to evaluate dietary sources and the trophic position of fish. There is the need to better understand the pattern of isotope enrichment between consumers and diets under laboratory conditions. Methods: We studied the changes in stable carbon and nitrogen isotopes of juvenile brown-marbled groupers during a feeding experiment in 2009. Fish were grown in aquaria and fed a sole source of protein for 56 days and analyzed for δ 13 C and δ 15 N ratios in whole fish, muscle, and liver tissues.Results: At the end of the 56-day feeding experiment, fish grew to an average of 55.6 g from an average of 22.5 g. Compared to the dietary isotope compositions, whole fish and muscle tissues of the juvenile groupers were enriched in δ 13 C by 1.6 and 0.5%, while the liver was depleted by 1.3%. The δ 15 N enrichments were 1.6% for whole fish, 1.3% for muscle, and 1.0% for liver. Except for liver, δ 15 N isotope values increased significantly with time. Conclusions:The small change in δ 13 C between the diet and fish suggests that little isotope alteration is occurring during the assimilation of dietary carbon. This provides a basis for estimates of the importance of different sources of dietary components when contrasted with the isotope values from a formulated diet with known isotope values of the different components. The smaller than expected δ 15 N enrichment in all tissue suggests that isotope values from a wild fish sample may not always reach isotope equilibrium with the current diet, and an inference about recent dietary sources and an estimate of the consumer's trophic position should be evaluated with caution.

Five isonitrogenous and isocaloric diets were fed to juvenile cobia, to assess the relative contribution of different proteins (fish meal, soybean meal, corn gluten and beer yeast) to the growth of cobia. The dietary effects on nitrogen and carbon turnover and on the isotopic diet-consumer discrimination factors (D 15 N and D 13 C) were also assessed. Growth results showed that the final body weight, growth rate, feed conversion ratio and protein efficiency ratio of cobia fed diets with alternative protein were significantly lower (P < 0.05) than cobia fed diet formulated with 100% fish meal. The estimated half-lives of nitrogen and carbon ranged between 9-11 days and 6-8 days, respectively, with significant differences among treatments (P < 0.05). D 15 N ranged between 0.0-1.2& and À0.1-1.6& in whole fish and muscle and D 13 C ranged between 3.8-5.1& and 4.0-5.1& in whole fish and muscle respectively. Diets were formulated with low levels of dietary nitrogen (10%) supplied by alternative protein sources substituting fish meal. The relative contributions of the dietary nitrogen supplied from these sources to the growth of whole fish and muscle tissue ranged between 4.9-5.2% and 5.9-7.7% respectively. Results indicated that growth accounted for the majority of observed isotopic change in animals under all treatments. In whole animals and muscle tissue, isotopic change due to metabolism occurred faster for carbon stable isotopes than for nitrogen stable isotopes. Cobia fed diets formulated with alternative proteins showed reduced nitrogen turnover rate and increased D 15 N.