Effect of novaluron on microbial biomass,respiration, and fluorescein diacetate-hydrolyzing activity in tropical soils

The aim of this study was to assess the potential harmful effects of novaluron on soil microbiological parameters in clay loam alluvial soil (Typic udifluvent) and coastal saline soil (Typic endoaquept) under controlled laboratory tests. The applications of novaluron were made at or above the recommended rates, which includes field rate (FR), two times (2FR), and ten times (10FR) the FR. The laboratory incubation study was carried out at 60% of maximum water holding capacity of soils and at 30°C. Novaluron application rate even up to 10FR resulted in a short-lived and transitory toxic effect on soil microbial biomass C and fluorescein diacetate-hydrolyzing activity. Microbial metabolic quotient changed but for a short period. It can be concluded that novaluron had a transient and negligible harmful effect on the soil microbiological parameters studied at higher rates than those usually used in the field.     

基于RBF神经网络的非线性观察器设计

提出了一种新的非线性观察器设计方法。与一般方法采用神经网络逼近整个非线性系统不同，该方法用RBF神经网络逼近系统的非线性项，故提高了状态估计的精度。基于李亚普诺夫方法，证明了状态估计误差渐近稳定且渐近收敛到零。仿真结果表明，所提出的非线性观察器设计方法具有良好的性能。在故障检测、状态估计等领域具有广泛的应用前景。     

Salinity Preference of Two Diatoms and Their Growth Performance in Three Prepared and Two Alternative On-Farm Media Sources

ABSTRACT

Salinity and preferred nutrient composition of Chaetoceros affinis and Skeletonema costatum were tested. Salinity was tested at 12, 16, 23, 28, and 32 ppt. Three compositions of nitrogen (N), phosphorus (P), and potassium (K) and two on-farm low-cost alternative media sources, cow urine (CU) and hatchery waste water (HWW), were tested to find the suitable NPK ratio and to determine the efficacy of the on-farm media respectively. Chaetoceros affinis preferred 23 ppt salinity, while Skeletonema costatum preferred both 28 and 32 ppt. Among the NPK treatments, higher cell density was observed in 4:1:1 followed by 4:2:1 ratios. Significant differences in maximum cell density of both species were observed in the NPK treatments while only S. costatum showed significant difference in CU and HWW.     

In-vitro characterization of the behaviour of Macrophomina phaseolina (Tassi) Goid at the rhizosphere and during early infection of roots of resistant and susceptible varieties of sesame

There are major gaps in our knowledge of the stages of infection in soil borne pathogens. Soil borne diseases, such as charcoal root rot caused by Macrophomina phaseolina on sesame, have been studied, yet due to the difficulty in observing fungal behaviour in the soil, there has been no detailed study of the infection events. Moreover no study has attempted to compare the infection events in roots of resistant versus susceptible hosts. We present the first ultra-structural report to characterize the behaviour of the fungus in the proximity of the root, the appearance of fungal hyphae on the surface of roots, microsclerotia formation on hyphal strands, early penetration events and subsequent infection processes of M. phaseolina in sesame. We observed distinct differences in fungal behaviour in the rhizosphere and during infection of susceptible and resistant varieties. This study also describes a framework for comparative experiments. The possible reasons for the difference in behaviour of M. phaseolina in the vicinity of and during infection of roots of resistant vs. susceptible varieties of sesame and its implications for disease resistance are discussed.     

Habitats across the life cycle of hilsa shad (Tenualosa ilisha) in aquatic ecosystem of Bangladesh

Aquatic habitat connectivity is vital for the continued existence of migratory fish. Using GIS and outranking multicriteria analysis based on hydrometeorological data, this study describes habitat preference of egg, fry, juvenile and adult phases of hilsa shad, Tenualosa ilisha (Hamilton), as well as their spawning areas in the aquatic ecosystems of Bangladesh. The total area studied was 29 484 km², about 29% of which belonged to the Meghna, Shahbajpur, Tetulia and Ander Manik rivers, and the channels of Sandwip, Kutubdia and Moheshkhali islands, which provide the most suitable habitat for the species. An additional 27% of moderately suitable area was located in other deltaic rivers and inshore waters. The remaining 44% was offshore deeper water, which was least suitable for hilsa. The most suitable area for spawning, eggs, fry, adults and juveniles was 6, 11, 29, 38 and 56% of the area, respectively. The model outputs were validated against field measurements and fishers’ indigenous knowledge with an accuracy level of 92%. Thus, this study provides key information about the location of hilsa at different stages of its life cycle, information useful in understanding its occurrence over a relatively large geographical area. Information of this kind is useful in fishery conservation and management.     

Bovine herpesvirus type 1 (BHV-1) mutant lacking U(L)49.5 luminal domain residues 30-32 and cytoplasmic tail residues 80-96 induces more rapid onset of virus neutralizing antibody and cellular immune responses in calves than the wild-type strain Cooper

Bovine herpesvirus type 1 (BHV-1) envelope protein U(L)49.5 inhibits transporter associated with antigen processing (TAP) and down-regulates cell-surface expression of major histocompatibility complex (MHC) class I molecules to promote immune evasion. Earlier, we have constructed a BHV-1U(L)49.5Δ30-32 CT-null virus and determined that in the infected cells, TAP inhibition and MHC-I down regulation properties of the virus are abolished. In this study, we compared the pathogenicity and immune responses in calves infected with BHV-1U(L)49.5Δ30-32 CT-null and BHV-1 wt viruses. Following primary infection, both BHV-1 wt and BHV-1U(L)49.5Δ30-32 CT-null virus replicated in the nasal epithelium with very similar yields. BHV-1 antigen-specific CD8+ T cell proliferation as well as CD8+ T cell cytotoxicity in calves infected with the BHV-1U(L)49.5Δ30-32 CT-null virus peaked by 7 dpi (P<0.05) which is 7 days earlier than that of BHV-1 wt-infected calves. Further, virus neutralizing antibody (VN Ab) titers and IFN-γ producing peripheral blood mononuclear cells (PBMCs) in the U(L)49.5 mutant virus-infected calves, also peaked 7 days (IFN-γ; P<0.05) and 14 days (VN Ab; P<0.05) earlier, respectively. Therefore, relative to wt in the BHV-1U(L)49.5 mutant virus-infected calves, primary neutralizing antibody and cellular immune responses were induced significantly more rapidly.     

Construction and characterization of a glycoprotein E gene-deleted bovine herpesvirus type 1 recombinant

OBJECTIVE: To construct and characterize a recombinant glycoprotein (g)E gene-deleted bovine herpesvirus (BHV) type 1 (BHV-1). PROCEDURE: The BHV-1 gEgene-coding region and the flanking upstream and downstream sequences were cloned. The aforementioned cloned DNA was digested with suitable enzymes to release the amino terminal two thirds of that region, and was ligated to the beta-galactosidase (beta-gal) gene. The resulting plasmid DNA was cotransfected with DNA from full-length, wild-type (WT), BHV-1 Cooper strain of the virus. Recombinant viruses expressing beta-gal (blue plaques) were plaque purified and assayed further by blot hybridization for genetic characterization and by immunoblotting for reactivity against BHV-1 gE peptide-specific rabbit polyclonal antibody. One recombinant virus, gEdelta3.1IBR, was characterized in vitro and in vivo. The ability of the recombinant virus to induce BHV-1 neutralizing antibodies in infected calves was investigated by plaque-reduction tests. RESULTS AND CONCLUSIONS: The gEdelta3.1IBR virus contained a deletion in the viral gE gene-coding sequences where a stable chimeric reporter (beta-gal) gene was inserted. One-step growth kinetics and virus yield of the recombinant and parent viruses were similar, but early after infection, the recombinant virus yield was comparatively less. After intranasal inoculation, the recombinant gEdelta3.1IBR virus replicated in the upper respiratory tract of calves, but the amount of progeny viruses produced was hundredsfold reduced, and duration of virus shedding was shorter. Results of in vivo calf experiments and serum neutralization tests indicated that deleting the gE gene has little effect on inducing neutralizing antibodies against BHV-1, but is sufficient to reduce BHV-1 virulence in calves.     

孟加拉国丘陵地带桔园和灌木林地土壤物理性质的比较评价(英文)

对孟加拉国丘陵地带Mro部落经营的桔园与灌木林35%和55%两种坡地土壤物理性质进行了比较与评价。每一块用地内挖掘3个土壤剖面采集不同深度(0-5cm,5-15cm and 15-30cm)的土壤样品,测定土壤水分、有机质含量和土壤密度。最大持水量、田间持水量、干或湿土壤容重和土壤孔隙度的测定仅限于表层土壤。两种坡地桔园3个深度的土壤水分含量均显著高于灌木林地相同深度的土壤水分。桔园在55%坡地内土壤有机质含量低于林地含量值,而在35%坡地内的含量值则高于林地值。两块样地内上述两项测定值均在表层土壤中最高,且随土层深度的增加而降低。与灌木林地比较,桔园地表层土壤最大持水量、孔隙度和3个不同深度的土壤密度均较低。两块用地内不同坡地的表层土田间持水量有所差异,且桔园地干或湿表层土壤容重高于林地内的数值。表5参23。