PCR detection and analysis of Pasteurella multocida from the tonsils of slaughtered pigs in Vietnam

A total of 36 tonsil swab samples were collected from healthy swine prior to slaughter at the abattoirs in Can tho and Tien giang provinces of Southern Vietnam. The presence of Pasteurella multocida in these samples was detected by the combination of direct cultivation and isolation, mouse inoculation and the polymerase chain reaction (PM-PCR). P. multocida was detected in 16 samples by PCR, with 17 strains ultimately isolated. All samples were negative for serogroup B by HSB-PCR and conventional serotyping, with isolates identified as A:3, D:1 or D:3. In addition, all samples were determined to be negative for the P. multocida toxin (PMT). Characterisation of isolated P. multocida by REP-PCR and biotyping revealed nine distinct REP profiles and seven biotypes among the 17 isolates. Some correlation was seen with P. multocida isolated from a previous Australian outbreak of acute swine pasteurellosis, and those isolated from fowl cholera outbreaks in Vietnamese poultry.     

Development of nursery culture techniques for the mud crab Scylla paramamosain (Estampador)

Cannibalism is one of the main causes of mortality in the culture of the mud crab Scylla paramamosain, particularly in the early post‐larval and juvenile stages when the densities of hatchery‐reared crabs may be very high before stocking into ponds or release into the wild for stock enhancement. In a series of experiments investigating cannibalism mitigation, the influence of stocking density, the effectiveness of sand substrate, brick and shell shelters and feed type were compared in culture of crabs from instar 1 for short nursery periods of 15–30 days. Inclusion of brick and shell shelters significantly increased survival over sand substrate alone. However, inclusion of shelters did not affect growth rates. In scaled‐up nursery production in lined‐ponds, with shelters, live Artemia biomass and fresh chopped shrimp or tilapia were found to be equally effective feeds for juvenile crabs stocked at a density of 70 m⁻² from instar 1 and grown for 30 days [52–66% survival, 21.6–24.6 mm carapace width (CW)]. In an extended nursery period for a further 30 days, crabs of 22 mm CW, stocked at 30 m⁻² in the same ponds, attained a final size of 34.5–36.2 mm CW with a survival of 64.3–67.0% using the same feeds.     

How do earthworms influence organic matter quantity and quality in tropical soils?

Earthworms are important regulators of soil structure and soil organic matter (SOM) dynamics; however, quantifying their influence on SOM cycling in tropical ecosystems remains little studied. Simulated rainfall was used to disrupt casts produced by Amynthas khami and their surrounding soil (control) into a range of small sized aggregates (50-250, 250-500, 500-2000 and 2000-5000 μm). To gain insight into how earthworms influence SOM biogeochemical composition in the aggregates, we carried out elemental and stable isotope analysis, and analytical pyrolysis (Py GC/MS). We also characterized their lignin component after oxidation with cupric oxide (CuO).The C content of smaller size fractions (<500 μm) in the control soil was higher than in the larger fractions. Our study therefore suggests that the aggregate hierarchy concept, which is used to understand soil aggregates and SOM dynamics in temperate soils, may not be applicable to the tropical Acrisol studied here. Earthworms modified SOM organization in soil aggregates. Although the isotope analyses were useful for highlighting SOM enrichment in the earthworm casts, aggregate fractions could not be classified according to particle size. Molecular analyses were necessary to indicate that SOM in all size fractions of casts consisted of relatively undecomposed material. Protection of the most labile SOM structures occurred in the smallest aggregate size fraction (50-250 μm). Py GC/MS showed that earthworm casts and control aggregates <2000 μm could be clearly distinguished according to the molecular properties of their SOM. Aggregates larger than 2000 μm, however, were most probably composed of all fractions and were not different. As a consequence, our results indicate that studies to determine the impact of earthworms on SOM turnover in soil are spatially dependant on the scale of observation.     

Anti-Inflammatory Components of the Starfish Astropecten polyacanthus

Inflammation is important in biomedical research, because it plays a key role in inflammatory diseases including rheumatoid arthritis and other forms of arthritis, diabetes, heart disease, irritable bowel syndrome, Alzheimer’s disease, Parkinson’s disease, allergies, asthma, and even cancer. In the present study, we describe the inhibitory effect of crude extracts and steroids isolated from the starfish Astropecten polyacanthus on pro-inflammatory cytokine (Interleukin-12 (IL-12) p40, interleukin-6 (IL-6), and tumor necrosis factor α (TNF-α)) production in lipopolysaccharide (LPS)-stimulated bone marrow-derived dendritic cells (BMDCs). Among those tested, compounds 5 and 7 showed potent inhibitory effects on the production of all three pro-inflammatory cytokines with IC₅₀ values ranging from 1.82 ± 0.11 to 7.00 ± 0.16 μM. Potent inhibitory activities were also observed for compound 1 on the production of IL-12 p40 and IL-6 with values of 3.96 ± 0.12 and 4.07 ± 0.13 μM, respectively, and for compounds 3 and 4 on the production of IL-12 p40 with values of 6.55 ± 0.18 and 5.06 ± 0.16 μM, respectively. Moreover, compounds 2 (IC₅₀ = 34.86 ± 0.31 μM) and 6 (IC₅₀ = 79.05 ± 2.05 μM) exhibited moderate inhibitory effects on the production of IL-12 p40, whereas compounds 3 (IC₅₀ = 22.80 ± 0.21 μM) and 4 (IC₅₀ = 16.73 ± 0.25 μM) moderately inhibited the production of TNF-α and IL-6, respectively.     

Frequent use of colistin-based drug treatment to eliminate extended-spectrum beta-lactamase-producing <Emphasis Type="Italic">Escherichia coli</Emphasis> in backyard chicken farms in Thai Binh Province,Vietnam

Reports of livestock infections with extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-E) are increasing. Based on interviews conducted over a 6-month period, we found that veterinarians in the Vietnamese province of Thai Binh prefer to prescribe colistin-based drugs (CBD) in chicken farms. We aimed to clarify whether CBD use selects for strains of colistin-resistant ESBL-E. With the cooperation of seven local households, we detected ESBL-E in chickens’ feces after treating chickens with CBD. Phylogenetic groupings and the presence of CTX-M/AmpC genes were determined, and the multi-antibiotic susceptibility of isolates was analyzed. Our results showed that ESBL-E presented in seven chickens’ feces from two households. Seventy-two percent of ESBL-E isolates harbored CTX-M9 and the phylogenetic group A; the colistin minimum inhibitory concentration (MIC) of all isolated ESBL-E ranged from 0.064 to 1 μg mL^?1. Moreover, ESBL-E isolates were used to experimentally select for colistin resistance, and the effect of commercial CBD on ESBL-E was investigated. The results showed that an ESBL-E strain with a colistin MIC of 4 μg mL^?1 was able to grow in media with CBD. Although CBD treatment was effective, in vitro experiments demonstrated that ESBL-E can easily acquire colistin resistance. Therefore, restrictions on colistin use are necessary to prevent the emergence of colistin-resistant bacteria.     

Ammonia volatilization from Vietnamese acid sulfate paddy soil following application of digested slurry from biogas digester

Paddy and Water Environment - In some areas of Vietnam, digested slurry from biogas digesters is discharged into canals without wastewater treatment. In order to reduce environmental pollution,...     

Assessment of pregnancy‐associated glycoprotein (PAG) concentrations in swamp buffalo samples from fetal and maternal origins by using interspecies antisera

Pregnancy‐associated glycoproteins (PAG) constitute a large family of glycoproteins found in the outer placental epithelial cell layer of the placenta in Eutherian species. In ruminants, they are noted to be structurally closely related among the different species. This study was designed to determine PAG concentrations in maternal and fetal plasma, allantoic and amniotic fluids in buffalo species. Antisera (AS) generated in rabbits against distinct PAG molecules were used in three radioimmunoassay (RIA)‐PAG systems: RIA‐1 (antiserum raised against bovine PAG67kDa; AS#497), RIA‐2 (antiserum raised against caprine PAG55 + 62 kDa; AS#706) or RIA‐3 (antiserum raised against buffalo PAG; AS#859). Samples were collected at a slaughterhouse (n = 67). PAG concentrations determined by RIA‐2 gave significantly higher results in both allantoic and amniotic fluids (12.7 ± 2.1 ng/mL and 24.0 ± 7.3 ng/mL, respectively). Regarding maternal and fetal plasma, PAG concentrations obtained by RIA‐2 (21.8 ± 2.4 ng/mL and 20.2 ± 2.5 ng/mL, respectively) and RIA‐3 (25.0 ± 2.2 ng/mL and 21.9 ± 3.2 ng/mL, respectively) were higher than those obtained by RIA‐1 (15.5 ± 1.4 ng/mL and 16.1 ± 1.8 ng/mL, respectively). The correlation among the three systems was very high. The study clearly reveals the ability of different PAG‐RIA systems to measure PAG concentration in swamp buffalo samples.     

Effects of application for international quality assurance certifications on the farm’s profit: evidence from Vietnamese shrimp

Aquaculture International - Food incidents have led to the increase in demand for food products certified by an international quality assurance certification of consumers all over the world. Shrimp...     

棉花组织培养高效植株再生体系的建立

通过对影响棉花体细胞胚胎发生和植株再生关键因素的研究,建立了适用于广泛基因型的棉花组织培养高效胚胎发生与植株再生体系。从中棉所12、中棉所19、泗棉3号等20余个主栽品种诱导获得了胚胎发生和植株再生,有效地突破了棉花组织培养植株再生的基因型控制,使占我国棉田面积50%以上的品种均能诱导获得胚胎发生和再生植株。首次诱导获得直接胚胎发生,使棉花组织培养的周期由180d缩短到120d左右,减少了培养过程中变异的发生。该结果的获得必将大大促进植物细胞工程和基因工程在棉花遗传改良上的应用。