Experimental challenge studies in Vietnamese catfish,Pangasianodon hypophthalmus (Sauvage), exposed to Edwardsiella ictaluri and Aeromonas hydrophila

The two main diseases in the pangasius catfish industry are bacillary necrosis of Pangasianodon (BNP) and motile aeromonas septicaemia (MAS), where the aetiological agents have been identified as Edwardsiella ictaluri and Aeromonas hydrophila, respectively. In this study, apparently healthy Pangasianodon hypophthalmus were exposed to E. ictaluri, A. hydrophila or both bacterial species by intraperitoneal injection or immersion. There were 20 fish per treatment group, and the bacterial isolates used for the study were recovered from natural infections of BNP or MAS in farmed Vietnamese P. hypophthalmus. The results of the experimental infections mimicked the natural disease outbreaks reported from these pathogens in P. hypophthalmus. Furthermore, it was clearly demonstrated that E. ictaluri was only recovered from the fish exposed to the bacterium and not recovered from the animals receiving A. hydrophila.     

Genetic variation for bacterial wilt resistance in a population of tetraploid potato

Summary Genetic variance components and heritability were estimated for resistance to bacterial wilt in a population of tetraploid potato with resistance derived from several specific sources. Both additive and non-additive variance components were significant. Their relative magnitudes indicated the importance of non-additive gene action in the genetic control of the resistance. Narrow-sense heritability was relatively low for both disease index and % survival indicating that progress in population development would be slow. Broad-sense heritability was, however, relatively high which promises success of clonal selection in developing clonal resistant cultivars.     

Effects of resistance genes,heat tolerance genes and cytoplasms on expression of resistance to Pseudomonas solanacearum (E.F. Smith) in potato

Summary Effects of resistance genes and heat tolerance genes on expression of resistance to bacterial wilt caused by Pseudomonas solanacearum were investigated in 30 F₁ progenies from parents with different levels of bacterial wilt resistance and heat tolerance. A race 1 and a race 3 isolate of the bacterium were used for inoculation under screenhouse conditions at two locations. Results obtained indicated that with reduction in levels of parental resistance, resistance in the F₁ progenies was also reduced. Under hot conditions, a reduced heat tolerance in the genetic background also resulted in lower levels of resistance expression. The effect of heat tolerance tended to diminish at lower temperatures leaving the effect of resistance genes more consistent. There existed a strong interaction between resistance genes and genes for heat tolerance. The nature of resistance to bacterial wilt in potato and implications for breeding for resistance are discussed.Effects of reciprocal crosses on expression of resistance to a race 1 isolate under hot screenhouse conditions, were studied in 5 sets of reciprocal F₁ progenies involving different resistant and susceptible parents. The reciprocal differences observed were not significant suggesting absence of cytoplasmic effects on expression of resistance.     

Bioactive phytochemicals of leaf essential oils of Cinnamomum osmophloeum prevent lipopolysaccharide/D-galactosamine (LPS/D-GalN)-induced acute hepatitis in mice

The purpose of this study was to investigate the bioactive phytochemicals of leaf essential oils of Cinnamomum osmophloeum on lipopolysaccharide/D-galactosamine (LPS/D-GalN)-induced acute hepatitis. The results revealed that post-treatment with 100 μmol/kg trans-cinnamaldehyde, (-)-aromadendrene, T-cadinol, or α-cadinol significantly decreased the aspartate aminotransferase (AST), alanine aminotransferase (ALT), tumor necrosis factor-α (TNF-α), and interleukin 6 (IL-6) levels in serum. Moreover, both T-cadinol and α-cadinol treatments decreased the expressions of cleaved caspase-3 and cleaved poly-ADP ribose polymerase (PARP) in the liver tissues when compared with the LPS/D-GalN group. Liver histopathology also showed that silymarin, trans-cinnamaldehyde, (-)-aromadendrene, T-cadinol, or α-cadinol significantly reduced the incidence of liver lesions induced by LPS/D-GalN. These results suggest that the above phytochemicals exhibit potent hepatoprotection against LPS/D-GalN-induced liver damage in mice, and their hepatoprotective effects may be due to the modulation of anti-inflammatory activities.     

Surveillance of swine influenza viruses in sentinel familial farms in Hung Yen province in Northern Vietnam in 2013–2014

From May 2013 to April 2014, 15 swine family‐run farms (17 pig litters) in two districts in Hung Yen province, near Hanoi, were virologically and epizootiologically monitored for swine influenza viruses (SIV) monthly. No SIV was isolated from nasal swabs. Maternal antibodies were detected in 10 litters, and seroconversion against SIV was detected in six litters. There was a marked difference in patterns of SIV transmission in the two districts. Van Lam district which has low density of swine with mainly smallholder farms had low intensity of SIV, with much of the infection caused by H1N1 2009 pandemic‐like viruses A(H1N1)pdm09, likely originated from humans. In contrast, Van Giang district, which has high swine density and larger farms, had high levels of typical SIV (triple reassortants H3N2 and H3N2 Binh Duong lineage viruses) circulating within swine. With one exception, the SIV lineages detected were those we concurrently isolated from studies in a large central abattoir in Hanoi. Influenza‐like illness symptoms reported by farmers were poorly correlated with serological evidence of SIV infection.     

Evidence of intracellular stages in Trypanosoma (Megatrypanum) theileri in non-phagocytic mammalian cells

Trypanosoma (subgenus Megatrypanum) theileri was first identified over one hundred years ago, and is a widespread parasite in cattle. Its life cycle within the mammalian host has rarely been reported. Whether there is an intracellular stage in tissues is unknown and such a stage has not been demonstrated experimentally. Intriguingly, using Giemsa staining with light microscopy and transmission electron microscopy examination, we found that the parasite was able not only to attach to cells but also to invade several phagocytic and non-phagocytic mammalian cells. Based on these findings, we conducted further investigations using a special antibody in immunofluorescence confocal images. Moreover, we examined a series of possible events of cell invasion in T. theileri. The results revealed that GM1, a marker of membrane rafts, was implicated in the mechanism of entry by this parasite. After incubation with tissue culture trypomastigotes, the gelatinolytic activity was significantly increased and accumulated at the attachment sites. Using ultrastructural localization detection by CytoTracker live imaging and confocal immunofluorescence microscopy, we found that lysosome fusion and the autophagy pathway were engaged in invaginating processes. T. theileri amastigotes also invaded cells and were enclosed by the lysosomes. Furthermore, tissue-cultured trypomastigotes were found to be capable of triggering intracellular free Ca²⁺ transients and TGF-β-signaling. Our findings that intracellular amastigote stages exist in mammalian cells infected with T. theileri and that the invasion processes involved various host cell components and cell signalings were extremely surprising and warrant further investigation.     

Alternative Protein Sources in Artificial Diets for New Zealand's Black‐Footed Abalone,Haliotis iris,Martyn 1784, Juveniles

Growth and health parameters were tested in juvenile New Zealand black‐footed abalone, Haliotis iris, fed nine diets containing different protein sources (white and red fishmeal, blood meal, meat and bone meal, casein, soybean concentrate, wheat gluten, maize gluten, and Spirulina powder) over a 5‐mo period. The growth parameters measured included shell length, total animal weight, and soft body and gonad weights. The health indicators included survival, goblet cell counts, and epithelium thickness of the tentacle region. Proximate analyses and amino acid and fatty acid profiles were also determined on the diets, soft body tissues and shell materials to evaluate the nutrient contents (diet and animal) and requirements (animal). Measurements of soft body, gonad, and shell growth parameters indicated that white and red fishmeals generally result in better growth. Animals fed blood meal had the lowest survival rates and crude protein contents. Spirulina produced animals with the heaviest shells and soybean treatments produced animals with the highest gonad to soft body ratios. Significantly lower acid/basic amino acid ratios were found in fishmeal diets, indicating that animals fed fishmeal may incorporate more aragonite than calcite in their shells.     

Block copolymers containing poly (3-hydroxybutyrate-co-3-hydroxyvalerate) and poly (<Emphasis Type="Italic">ɛ</Emphasis>-caprolactone) units: Synthesis,characterization and thermal degradation

Biodegradable block copolymers containing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly (ɛ-caprolactone) (PCL) units (PHCLs) with different contents of PCL block were synthesized successfully by using telechelic hydroxylated PHBV (PHBV-diol) with low molecular weight as a macroinitiator to initiate ring-opening bulk polymerization of ɛ-caprolactone (ɛ-CL). The chemical structure and molecular weight were characterized by 1H NMR, FTIR and GPC. The PHBV and PCL blocks in PHCLs were miscible in amorphous state, and formed separate crystalline phases with lower crystallinity than corresponding homopolymers, which was characterized by DSC and WAXD. The results of TGA showed that PHCLs underwent a two-step thermal degradation process. The thermal degradation process of PCL blocks was significantly different from PCL homopolymers. The activation energies of thermal degradation of PCL blocks calculated by Horowitz and Metzger method were much higher than that of each step of thermal degradation of PCL homopolymers.     

Application and development of a decision-support system for assessing water shortage and allocation with climate change

The assessment to vulnerability of the water supply system needs several modeling tools and cases to simulate. A decision-support tool which integrates the common procedures of impact assessment of climate change, downscaling, weather generation, hydrological model, and interface for linking system dynamics model is proposed here. In this study, the impact of climatic change and growing water demand to the water supply system in Touchien river basin in Taiwan was derived. The vulnerability for the current water supply system was estimated for present and future conditions. The result demonstrated that the water supply system could meet the water demand in Touchien river basin but might be subjected to serious water shortage due to climatic change and expanded water demand. Results are expected to give the authorized government sectors a hint for instituting water policy and implementing allocation measures for irrigational water.