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The aim of this review is to provide a review of the immune system in fish, including the ontogeny, mechanisms of unspecific and acquired immunity and the action of some immunomodulators. Fish rely on their innate immune system for an extended period of time, beginning at the early stages of embryogenesis. The components of the innate immune response are divided into physical, cellular and humoral factors and include humoral and cellular receptor molecules that are soluble in plasma and other body fluids. The lymphoid organs found in fish include the thymus, spleen and kidney. Immunoglobulins are the principal components of the immune response against pathogenic organisms. Immunomodulatory products, including nucleotides, glucans and probiotics, are increasingly used in aquaculture production. The use of these products reduces the need for therapeutic treatments, enhances the effects of vaccines and, in turn, improves the indicators of production.

Reactive oxygen species are believed to perform multiple roles during plant defense and possibly as cellular signaling molecules. In animals, nitric oxide (NO) is an important redox-active signaling molecule. Here we show that infection of resistant, but not susceptible, tobacco with tobacco mosaic virus resulted in enhanced NO synthase (NOS) activity. Furthermore, administration of NO donors or recombinant mammalian NOS to tobacco plants or tobacco suspension cells triggered expression of the defense-related genes encoding pathogenesis-related 1 protein and phenylalanine ammonia lyase (PAL). These genes were also induced by cyclic GMP (cGMP) and cyclic ADP-ribose, two molecules that can serve as second messengers for NO signaling in mammals. Consistent with cGMP levels. Furthermore, NO-induced activation of PAL was blocked by 6-anilino-5,8-quinolinedione and 1H-(1,2,4)-oxadizole[4,3-alpha]quinoxalin-1-one, two inhibitors of guanylate cyclase. Although 6-anilino-5,8-quinolinedione fully blocked PAL activation, inhibition by 1H-(1,2,4)-oxadiozole[4,3-alpha]quinoxalin-1-one was not entirely complete, suggesting the existence of cGMP-independent, as well as cGMP-dependent, NO signaling. We conclude that several critical players of animal NO signaling are also operative in plants

Background Malaria remains as a major global problem, being one of the infectious diseases that engender highest mortality across the world. Due to the appearance of resistance and the lack of an effective vaccine, the search of novel anti-malarials is required. Deoxyuridine 5′-triphosphate nucleotido-hydrolase (dUTPase) is responsible for the hydrolysis of dUTP to dUMP within the parasite and has been proposed as an essential step in pyrimidine metabolism by providing dUMP for thymidylate biosynthesis. In this work, efforts to validate dUTPase as a drug target in Plasmodium falciparum are reported. Methods To investigate the role of PfdUTPase in cell survival different strategies to generate knockout mutants were used. For validation of PfdUTPase as the intracellular target of four inhibitors of the enzyme, mutants overexpressing PfdUTPase and HsdUTPase were created and the IC50 for each cell line with each compound was determined. The effect of these compounds on dUTP and dTTP levels from P. falciparum was measured using a DNA polymerase assay. Detailed localization studies by indirect immunofluorescence microscopy and live cell imaging were also performed using a cell line overexpressing a Pfdut -GFP fusion protein. Results Different attempts of disruption of the dut gene of P. falciparum were unsuccessful while a 3′ replacement construct could recombine correctly in the locus suggesting that the enzyme is essential. The four 5′-tritylated deoxyuridine analogues described are potent inhibitors of the P. falciparum dUTPase and exhibit antiplasmodial activity. Overexpression of the Plasmodium and human enzymes conferred resistance against selective compounds, providing chemical validation of the target and confirming that indeed dUTPase inhibition is involved in anti-malarial activity. In addition, incubation with these inhibitors was associated with a depletion of the dTTP pool corroborating the central role of dUTPase in dTTP synthesis. PfdUTPase is mainly localized in the cytosol. Conclusion These results strongly confirm the pivotal and essential role of dUTPase in pyrimidine biosynthesis of P. falciparum intraerythrocytic stages.

Volatile and non-volatile compounds, which contribute to flavor in raw fish, were compared in raw, cooked and recooked silver carp. In total, 20, 34 and 34 volatile compounds, including aldehydes, alcohols, ketones, hydrocarbons and heterocyclic compounds, were identified in raw, cooked and recooked samples, respectively. Cooking the samples resulted in a significant increase in volatile compounds and the formation of new aldehydes, alcohols, ketones, hydrocarbons and heterocyclic compounds. In addition, the content of free amino acids (FAA) decreased dramatically, and the amount of nucleotides and small peptides significantly changed. With recooking of the samples, the levels of most of the volatile compounds decreased significantly, and there was a substantial change in nucleotides and small peptides. However, the effect of recooking on FAA was not observable.

Earlier studies with Arabidopsis thaliana exposed to ultraviolet B (UV-B) and ozone (O3) have indicated the differential responses of superoxide dismutase and glutathione reductase. In this study, we have investigated whether A. thaliana genotype Landsberg erecta and its flavonoid-deficient mutant transparent testa (tt5) is capable of metabolizing UV-B- and O3-induced activated oxygen species by invoking similar antioxidant enzymes. UV-B exposure preferentially enhanced guaiacol-peroxidases, ascorbate peroxidase, and peroxidases specific to coniferyl alcohol and modified the substrate affinity of ascorbate peroxidase. O3 exposure enhanced superoxide dismutase, peroxidases, glutathione reductase, and ascorbate peroxidase to a similar degree and modified the substrate affinity of both glutathione reductase and ascorbate peroxidase. Both UV-B and O3 exposure enhanced similar Cu,Zn-superoxide dismutase isoforms. New isoforms of peroxidases and ascorbate peroxidase were synthesized in tt5 plants irradiated with UV-B. UV-B radiation, in contrast to O3, enhanced the activated oxygen species by increasing membrane-localized NADPH-oxidase activity and decreasing catalase activities. These results collectively suggest that (a) UV-B exposure preferentially induces peroxidase-related enzymes, whereas O3 exposure invokes the enzymes of superoxide dismutase/ascorbate-glutathione cycle, and (b) in contrast to O3, UV-B exposure generated activated oxygen species by increasing NADPH-oxidase activity

The application of a moderate water deficit (water potential of -1.3 MPa) to pea (Pisum sativum L. cv Lincoln) leaves led to a 75% inhibition of photosynthesis and to increases in zeaxanthin, malondialdehyde, oxidized proteins, and mitochondrial, cytosolic, and chloroplastic superoxide dismutase activities. Severe water deficit (-1.9 MPa) almost completely inhibited photosynthesis, decreased chlorophylls, beta-carotene, neoxanthin, and lutein, and caused further conversion of violaxanthin to zeaxanthin, suggesting damage to the photosynthetic apparatus. There were consistent decreases in antioxidants and pyridine nucleotides, and accumulation of catalytic Fe, malondialdehyde, and oxidized proteins. Paraquat (PQ) treatment led to similar major decreases in photosynthesis, water content, proteins, and most antioxidants, and induced the accumulation of zeaxanthin and damaged proteins. PQ decreased markedly ascorbate, NADPH, ascorbate peroxidase, and chloroplastic Fe-superoxide dismutase activity, and caused major increases in oxidized glutathione, NAD+, NADH, and catalytic Fe. It is concluded that, in cv Lincoln, the increase in catalytic Fe and the lowering of antioxidant protection may be involved in the oxidative damage caused by severe water deficit and PQ, but not necessarily in the incipient stress induced by moderate water deficit. Results also indicate that the tolerance to water deficit in terms of oxidative damage largely depends on the legume cultivar

OAA, the potent anti-HIV protein from Oscillatoria agardhii NIES-204 belongs to a new lectin family, shows strict binding specificity for high-mannose N-glycans, and has an extremely high association constant in the picomolar range for recombinant gp120, an envelope protein of HIV. In this study we have cloned the gene encoding OAA from the genomic DNA of the cyanobacterium, and efficiently expressed the recombinant lectin (rOAA) in Escherichia coli. The rOAA expressed as a His-tagged fusion protein was recovered in a soluble form and purified in high yield (48 mg/l 1-culture) by metal chelate chromatography. The fusion protein was cleaved with factor Xa, and the resulting rOAA was isolated in a final yield of 14.8 mg/l 1-culture by reversed-phase HPLC. Both the N-terminal sequence and the molecular mass of rOAA were found to be identical with those of OAA. The rOAA was fully functional with the same properties as OAA, as evidenced by hemagglutination activity, hapten-inhibition test, and binding specificity for high-mannose-type N-glycans. This rOAA should be applicable as a specific probe for high-mannose N-glycans and should contribute to elucidation of the molecular basis of its strict carbohydrate-binding specificity and potent anti-HIV activity.

The phytochrome family of photoreceptors monitors the light environment and dictates patterns of gene expression that enable the plant to optimize growth and development in accordance with prevailing conditions. The enduring challenge is to define the biochemical mechanism of phytochrome action and to dissect the signaling circuitry by which the photoreceptor molecules relay sensory information to the genes they regulate. Evidence indicates that individual phytochromes have specialized photosensory functions. The amino-terminal domain of the molecule determines this photosensory specificity, whereas a short segment in the carboxyl-terminal domain is critical for signal transfer to downstream components. Heterotrimeric GTP-binding proteins, calcium-calmodulin, cyclic guanosine 5'-phosphate, and the COP-DET-FUS class of master regulators are implicated as signaling intermediates in phototransduction

MicroRNAs are short 21-22 nucleotide single strand RNAs that are involved in post-transcriptional regulation of gene expression. Most microRNAs are first transcribed as long primary microRNAs and then undergo a two step-wise sequential processing to yield single-stranded mature microRNAs. It has been suggested that the loop region of primary microRNAs plays an important role in regulating microRNA biogenesis and target recognition. However, despite the fact that several single nucleotide polymorphisms have been identified in mature microRNA sequences and are related to human diseases, it remains unclear whether and how the single nucleotide polymorphisms in the loop regions of primary microRNAs would affect the biogenesis and function of microRNAs. Herein, we provide evidence that primary microRNAs loop nucleotides control the accuracy and efficiency of microRNA processing. Accordingly, we identified 32 single nucleotide polymorphisms in the loop regions of human primary microRNAs using bioinformatics, and further validated three loss-of-function and one gain-of-function single nucleotide polymorphisms using dual-luciferase assays. Thus, these results reveal a critical regulatory role encoded in the loop nucleotides of primary microRNAs for microRNA processing and function.

The PKC1-MPK1 pathway in yeast functions in the maintenance of cell wall integrity and in the stress response. We have identified a family of genes that are putative regulators of this pathway. WSC1, WSC2, and WSC3 encode predicted integral membrane proteins with a conserved cysteine motif and a WSC1-green fluorescence protein fusion protein localizes to the plasma membrane. Deletion of WSC results in phenotypes similar to mutants in the PKC1-MPK1 pathway and an increase in the activity of MPK1 upon a mild heat treatment is impaired in a wsc delta mutant. Genetic analysis places the function of WSC upstream of PKC1, suggesting that they play a role in its activation. We also find a genetic interaction between WSC and the RAS-cAMP pathway. The RAS-cAMP pathway is required for cell cycle progression and for the heat shock response. Overexpression of WSC suppresses the heat shock sensitivity of a strain in which RAS is hyperactivated and the heat shock sensitivity of a wsc delta strain is rescued by deletion of RAS2. The functional characteristics and cellular localization of WSC suggest that they may mediate intracellular responses to environmental stress in yeast