Pathogenicity comparison of high- and low-virulence strains of Vibrio scophthalmi in olive flounder Paralichthys olivaceus

Vibrio scophthalmi, a bacterial pathogen of olive flounder Paralichthys olivaceus, exhibits strain-dependent virulence. No information is available on the comparative pathogenicity of different strains of V. scophthalmi toward olive flounder. In this study, high- and low-virulence strains (HVS and LVS, respectively) were compared in terms of their pathogenic characteristics, including adhesion and survival, superoxide dismutase (SOD) activity, and extracellular products (ECP) of bacterial cells. The cell-mediated defense of macrophages from olive flounder against V. scophthalmi infection in vitro was also investigated. The results demonstrated that the SOD activity of the HVS was higher than that of the LVS. The number of viable cells of the HVS in serum increased by two log units after 18 h, whereas that of the LVS decreased. The number of cells of the HVS in skin mucus increased significantly while that of the LVS remained constant. The LD₅₀ values of the HVS and LVS ECP toward olive flounder were 10.14 and 15.99 μg protein/g fish, respectively. The ECP were positive for naphthol-AS-BI-phosphohydrolase, lipase, gelatinase, and leucine arylamidase. The extracellular O₂ ^? overflow and intracellular O₂ ^? concentration of macrophages induced by the HVS were lower than those induced by the LVS. Significantly more nitric oxide was produced by the HVS than by the LVS.     

The Molecular Biology of the Interactions Between Trichoderma spp., Phytopathogenic Fungi, and Plants

ABSTRACT Trichoderma-based biofungicides are a reality in agriculture, with more than 50 formulations today available as registered products worldwide. Several strategies have been applied to identify the main genes and compounds involved in this complex, three-way cross-talk between the fungal antagonist, the plant, and microbial pathogens. Proteome and genome analysis have greatly enhanced our ability to conduct holistic and genome-based functional studies. We have identified and determined the role of a variety of novel genes and gene-products, including ABC transporters, enzymes and other proteins that produce or act as novel elicitors of induced resistance, proteins responsible for a gene-for-gene avirulent interaction between Trichoderma spp. and plants, mycoparasitism-related inducers, plant proteins specifically induced by Trichoderma, etc. We have transgenically demonstrated the ability of Trichoderma spp. to transfer heterologous proteins into plant during root colonization, and have used green fluorescent protein and other markers to study the interaction in vivo and in situ between Trichoderma spp. and the fungal pathogen or the plant.     

Molecular characterization of myostatin‐like genes expressed highly in the muscle tissue from Morotoge shrimp,Pandalopsis japonica

Myostatin is one of the transforming growth factor (TGF)‐β family members and plays inhibitory roles in the development and growth of muscle in mammals. Mammalian myostatins have been studied intensively, considering its medical and industrial potential use. Still, limited information is available about myostatin homologues in crustaceans. In the present study, we isolated for the first time cDNA that encodes for myostatin‐like protein (Pj‐MSTN) from Morotoge shrimp, Pandalopsis japonica. The putative mature peptide of Pj‐MSTN was composed of 109 amino acids, which contains an additional amino acid residue compared with mammalian myostatins. Pj‐MSTN exhibited 32% amino acid sequence identity and 52% similarity to human myostatin. Multiple sequence alignment analysis indicated that Pj‐MSTN shared the conserved proteolytic cleavage site (RXXR) for its maturation and nine cysteine residues for disulphide bridges. These results suggest that Pj‐MSTN has conserved the three‐dimensional structure of TGF‐β family members in vertebrates. Phylogenetic analysis suggests that Pj‐MSTN is a primitive form of vertebrate myostatin and GDF11. The expression of Pj‐MSTN was not just identified in muscular tissues, suggesting that Pj‐MSTN functions differently from mammalian myostatin. Ablation of the X‐organ/sinus gland complex significantly reduced the expression of Pj‐MSTN in most tissues, suggesting its potential association with moulting.     

Genetic variation and population structure of the Pacific cod <Emphasis Type="Italic">Gadus macrocephalus</Emphasis> in Korean waters revealed by mtDNA and msDNA markers

To investigate the extent of genetic differentiation among wild populations of the Pacific cod Gadus macrocephalus, we have examined genetic polymorphism at five locations within Korean waters [Boryeong in the West Sea (WC-BR); Jinhae Bay in the South Sea (SC-JH); Jumunjin (EC-JM), Jukbyeon (EC-JB), and Bangeojin (EC-BJ) off the eastern coast of Korea] using mitochondrial DNA (mtDNA) control region and microsatellite DNA (msDNA) markers. Nucleotide sequence analysis of 584 bp in the variable portion of the 5′ end of the mtDNA control region revealed 27 variable nucleotide sites among 184 individuals, which defined eight, three, and 11 haplotypes in the western, southern, and eastern coast populations, respectively. The mtDNA analysis revealed a low variability but significant local differentiation among populations from these three areas within Korean waters. msDNA analysis also revealed moderate polymorphism in the wild populations, with a mean of 13.8–22.6 alleles per locus for the five msDNA markers and observed (and expected) heterozygosities of 0.755 (0.825) for the WC-BR, 0.793 (0.810) for the SC-JH, 0.920 (0.905) for the EC-BJ, 0.783 (0.865) for the EC-JB, and 0.804 (0.812) for the EC-JM populations. Analysis of msDNA loci indicated that Pacific cod sampled at the WC-BR, SC-JH, and EC-JB sites belong to genetically distinct populations. However, no significant difference was found between the Pacific cod population from SC-JH and that from EC-BJ. Consequently, three genetically distinct populations, namely, WC-BR, SC-JH and EC-BJ, and EC-JB, were identified using msDNA analysis. These results indicate that genetically distinct populations of Pacific cod are present in Korean coastal waters where spawning aggregations occur.     

Cross‐Linked Resistant Starch: Preparation and Properties

Resistant starches (RS) were prepared by phosphorylation of wheat, waxy wheat, corn, waxy corn, high‐amylose corn, oat, rice, tapioca, mung bean, banana, and potato starches in aqueous slurry (≈33% starch solids, w/w) with 1–19% (starch basis) of a 99:1 (w/w) mixture of sodium trimetaphosphate (STMP) and sodium tripolyphosphate (STPP) at pH 10.5–12.3 and 25–70°C for 0.5–24 hr with sodium sulfate or sodium chloride at 0–20% (starch basis). The RS₄ products contain ≤100% dietary fiber when assayed with the total dietary fiber method of the Association of Official Analytical Chemists (AOAC). In vitro digestion of four RS₄ wheat starches showed they contained 13–22% slowly digestible starch (SDS) and 36–66% RS. However after gelatinization, RS levels fell by 7–25% of ungelatinized levels, while SDS levels remained nearly the same. The cross‐linked RS₄ starches were distinguished from native starches by elevated phosphorus levels, low swelling powers (≈3g/g) at 95°C, insolubilities (<1%) in 1M potassium hydroxide or 95% dimethyl sulfoxide, and increased temperatures and decreased enthalpies of gelatinization measured by differential scanning calorimetry.     

Synthesis and herbicidal activity of new benzenesulfonylureas

A series of benzenesulfonylurea derivatives possessing a branched hydroxymethyl moiety as an ortho-substituent were synthesized and found to have interesting herbicidal activity under submerged paddy conditions.     

Ectomycorrhizal fungal community associated with naturally regenerating Pinus densiflora Sieb. et Zucc. seedlings on exposed granite slopes along woodland paths

We investigated the ectomycorrhizal (EcM) fungal community of naturally regenerating Pinus densiflora seedlings on exposed decomposed granite (DG) slopes along woodland paths in the Republic of Korea. We sampled three- to five-year-old seedlings from slopes where DG was exposed (habitat S) and from the surrounding forest edge or gaps (habitat F). We classified EcMs into morphological groups and counted the number of root tips. The fungal taxa were determined by sequencing the internal transcribed spacer region of their nuclear rDNA. We observed a total of 27 EcM fungal taxa. Atheliaceae and Rhizopogon were the dominant taxa on exposed DG slopes. The fungal species compositions were similar between habitats (0.59 as calculated by the Morishita–Horn index). Fourteen fungal taxa were common to both habitats, and these accounted for more than 90% of the relative abundance in each habitat. There were no significant differences in relative abundance and colonization frequency of each EcM fungal taxon between the habitats, except for Russula sp. 2, which was significantly more frequent in habitat F than in habitat S. Our results indicated that P. densiflora seedlings on exposed DG slopes associated with EcM fungi that were common in forests and not specific to the exposed DG slopes.     

Oral administration of Salmonella enterica serovar Typhimurium expressing swine interleukin-18 induces Th1-biased protective immunity against inactivated vaccine of pseudorabies virus

Enhancing and/or modulating innate and adaptive immunity by cytokines appears to be greatly useful to provide effective protective immunity against infectious diseases. However, an effective delivery system for mass administration in livestock industry is needed because of limitations such as cost, labor, time, and protein stability. Here the immunomodulatory functions of swine interleukine-18 (swIL-18), known as IFN-γ-inducing factor (IGIF), were evaluated in a vaccination model of pseudorabies virus (PrV) using attenuated Salmonella enterica serovar Typhimurium as the oral delivery system. The oral administration of S. enterica serovar Typhimurium expressing swIL-18 prior to vaccination with inactivated PrV vaccine induced enhanced levels of serum PrV-specific IgG and its IgG2 isotype, compared to administration of S. enterica serovar Typhimurium harboring the empty vector. Furthermore, S. enterica serovar Typhimurium expressing swIL-18 mounted Th1-biased cellular immune responses against PrV antigen, as evaluated by the production of IFN-γ and IL-4 from peripheral blood mononuclear cells of piglets. Subsequently, Th1-biased immunity induced by S. enterica serovar Typhimurium expressing swIL-18 showed rapid response and rendered piglets displayed more alleviated clinical signs following the virulent PrV challenge. Also, this alleviation of clinical signs was further confirmed by the reduction of nasal excretion of PrV after challenge. The present study demonstrates the extended use of immunomodulatory functions of swIL-18 orally delivered by attenuated S. enterica serovar Typhimurium.     

Xylella fastidiosa plasmid-encoded PemK toxin is an endoribonuclease

Stable inheritance of pXF-RIV11 in Xylella fastidiosa is conferred by the pemI/pemK toxin-antitoxin (TA) system. PemK toxin inhibits bacterial growth; PemI is the corresponding antitoxin that blocks activity of PemK by direct binding. PemK and PemI were overexpressed in Escherichia coli and activities of each were assessed. Purified PemK toxin specifically degraded single-stranded RNA but not double-stranded RNA, double-stranded DNA, or single-stranded DNA. Addition of PemI antitoxin inhibited nuclease activity of PemK toxin. Purified complexes of PemI bound to PemK exhibited minimal nuclease activity; removal of PemI antitoxin from the complex restored nuclease activity of PemK toxin. Sequencing of 5' rapid amplification of cDNA ends products of RNA targets digested with PemK revealed a preference for cleavage between U and A residues of the sequence UACU and UACG. Nine single amino-acid substitution mutants of PemK toxin were constructed and evaluated for growth inhibition, ribonuclease activity, and PemI binding. Three PemK point-substitution mutants (R3A, G16E, and D79V) that lacked nuclease activity did not inhibit growth. All nine PemK mutants retained the ability to bind PemI. Collectively, the results indicate that the mechanism of stable inheritance conferred by pXF-RIV11 pemI/pemK is similar to that of the R100 pemI/pemK TA system of E. coli.