Design and evaluation of primer pairs for efficient detection of avian rotavirus

The use of molecular methods for rotavirus characterisation provides increased sensitivity for typing and allows the identification of putative reassortant strains. Reagents and methods for genotyping the virus need constant modification because of the reassortant nature of the virus. This study was aimed at designing and evaluating new oligonucleotide degenerate primer pairs that provide increased sensitivity and specificity for detecting avian rotavirus. Gene-specific primer pairs were designed by analysing different rotavirus strains isolated during the last decade by downloading them from the GenBank. The alignments were generated using clustal analysis from the BioEdit program. Degenerate nucleotides were included due to the reassortant nature of rotavirus. The consensus sequences were aligned using the BioEdit program and then treated with the Fast PCR software to derive the primers. The derived primer sequences were submitted for a BLAST search to ensure alignment was exclusive to the desired target genes. The designed primers had specific bands and were efficient in detecting rotavirus in faecal samples than previously published primers. Thus, a successful surveillance of rotaviruses requires that primer pairs be updated regularly in order to detect the emergence of novel or “unusual types”, which have occurred by genetic drift causing nucleotide changes at the primer binding sites that result in typing failures. We recommend the use of the proposed primers in molecular surveillance studies for efficient detection of avian rotavirus.     

猪败血型链球菌病的诊疗报告

本文阐述了猪链球菌病的临床症状、实验室检验及防治方法，力求为科学防控猪链球菌病提供有益的探索和参考。     

Physicochemical and kinetic characteristics of rhodanese from the liver of African catfish <Emphasis Type="Italic">Clarias gariepinus</Emphasis> Burchell in Asejire lake

Two forms of rhodanese were purified from the liver of Clarias gariepinus Burchell, designated catfish rhodanese I (cRHD I) and rhodanese II (cRHD II), by ion-exchange chromatography on a CM-Sepharose CL-6B column and gel filtration through a Sephadex G-75 column. The apparent molecular weight obtained for cRHD I and cRHD II was 34,500 ± 707 and 36,800 ± 283 Da, respectively. The subunit molecular weight determined by sodium dodecyl sulphate–polyacrylamide gel electrophoresis was 33,200 ± 283 and 35,100 ± 141 Da for cRHD I and cRHD II, respectively. Atomic absorption spectrophotometric analysis revealed that cRHD II contained a high level of iron (Fe), which presumably was responsible for the brownish colour of the preparation. In contrast, no Fe was identified in cRHD I, and its preparation was colourless. Further characterization of cRHD II gave true Michaelis–Menten constant (K _m) values of 25.40 ± 1.70 and 18.60 ± 1.68 mM for KCN and Na₂S₂O₃, respectively, an optimum pH of 6.5 and an optimum temperature of 40°C. The Arrhenius plot of the effects of temperature on the reaction rate consisted of two linear segments with a break occurring at 40°C. The apparent activation energy values from these slopes were 7.3 and 72.9 kcal/mol. Inhibition studies on the cRHD II enzyme showed that the activity of the enzyme was not affected by Mn²⁺, Co²⁺, Sn²⁺, Ni²⁺ and NH₄ ⁺, but Zn²⁺ inhibited the enzyme considerably.     

Studies on glutathione transferase from grasshopper (Zonocerus variegatus)

Glutathione transferase (GST) was purified from the hindgut of grasshopper (Zonocerus variegatus) a polyphagous insect. The purified enzyme had a native molecular weight of 40 kDa and a subunit molecular weight of 19 kDa. The purified enzyme could conjugate glutathione (GSH) with 1-chloro-2,4-dinitrobenzene (CDNB), paranitrobenzylchloride, paranitrophenylacetate, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBDCl), and 1,2-dichloro-4-nitrobenzene (DCNB) with specific activities of 3.3 ± 0.3, 0.49 ± 0.10, 0.10 ± 0.002, 1.2 ± 0.2, and 1.7 ± 0.4 μmol/min/mg protein, respectively. CDNB appears to be the best substrate with a specificity constant, k_cat/K_m, of 1.8 ± 0.1 × 10⁻⁴ M⁻¹ S⁻¹. The kinetic mechanism of Z. variegatus GST (zvGST) in the conjugation of GSH with some electrophilic substrates appears complex. Conjugation of GSH with DCNB was inhibited by high DCNB concentration, while with NBDCl, as the electrophilic substrates, different values of K_m were obtained at high and low concentrations of the substrates. Cibacron blue, hematin, S-hexylglutathione, and oxidized glutathione inhibited the enzyme with I₅₀ values of 0.057 ± 0.004, 0.80 ± 0.2, 33 ± 2 μM, and 5.2 ± 0.3 mM, respectively. The nature of inhibition by each of these inhibitors is either competitive or non-competitive at varying GSH or CDNB as substrates. NADH and NAD⁺ inhibited the enzyme with an I₅₀ value of 0.4 ± 0.01 and 11 ± 1 mM, respectively. NADH at a concentration of 0.54 mM completely abolished the activity. As part of its adaptation, the flexible kinetic pathway of detoxication by zvGST may assist the organism in coping with various xenobiotics encountered in its preferred food plants.     

Effect of Smoking Time and Temperature on the Proximate Composition and Quality of Milkfish Steaks

The effect of three smoking durations (60, 90, and 120 min) and two smoking temperatures (60°C and 70°C) on proximate composition and quality of brackish cultured milkfish steaks of 3 cm size was studied. No significant difference was observed in the sensory properties across all the samples, except in the overall acceptability of sample smoked at 60°C for 60 min. There was significant difference in the values obtained for the textures of all the samples. The L*a*b* values showed a significant difference in the raw and smoked samples. The moisture content showed significant difference in all six samples. Naphthalene, fluorine, and anthracene were detected in the raw sample and in all the smoked samples with significant difference, except for naphthalene. The effect of smoking on the sensory properties and the moisture content of a smoked fish sample are dependent on the smoking time and temperature. Polycyclic aromatic hydrocarbon (PAH) concentration in smoked fish can be a factor, based on both water pollution and the smoking procedure. Benzo-a-pyrene and PAH4, which are acceptable indicators of total PAH presence in smoked foods, were not detected in all the smoked samples, thereby indicating the products to be safe for consumption.     

Status of yam (Dioscorea spp.) in the Democratic Republic of Congo

Yam is an important tuber crop with enormous potential to enhance rural sustenance and livelihood in DRC. However, studies to enhance its genetic improvement are very far from sufficient with only a handful of information available on the crop. Yam has been treated as an orphan crop compared to contemporary crops such as cassava and sweet potato which have adapted to different cropping systems and become widespread in production. The lack of research attention to address the major production challenges has further decreased the value and potential of the crop compared to its contemporaries. These production constraints include lack of adequate quality planting materials, low yield potential, poor resistance/tolerance to yam mosaic and anthracnose diseases and ultimately poor tuber quality attributes focusing on tuber taste, flesh oxidation and dry matter contents of the majority of the farmers preferred varieties. In this review, we evaluated the status of yam in DRC and presented the needful activities to be incorporated for its improvement. Diversity has however been maintained mainly through ennoblement efforts in house gardens and small farmlands using traditional farming methods. Studies from other nations where yam has been successful with prominence in characterization and genetic improvement brought to light the need for DRC to consider yam as a staple carbohydrate food source, even to the extent of modifications in food public policy. Reversal of the yam's current stigma is a challenge to the scientific community and the population in general.     

Entertainment-Education Strategy Utilization for Agricultural Information Dissemination: Congruency Among Researchers,Extension Agents,and Farmers in Southwestern Nigeria

Several congruency studies exist on agricultural-related issues, but studies on congruency for entertainment-education (EE) utilization for agricultural information dissemination is limited. Congruency among researchers, extension agents, and farmers on the use of EE for agricultural information dissemination was examined. A multistage sampling procedure was used to select 161 respondents across respondent categories. A structured questionnaire was used to obtain data on respondents' perception and estimate of perception of other stakeholders to establish accuracy. Data were analyzed using Pearson product-moment correlation at p = 0.05. Results indicate congruence between researchers' perception and accuracy in establishing extension agents and farmers' opinion about media environment. A similar result was obtained for congruence between farmers' perception and other stakeholders' position on media environment. Congruence between extension agents, researchers, and farmers was accurate for infrastructural factors. Given the accurate predictions of each other's disposition to key variables, EE should be further exploited for agricultural information dissemination.     

Short‐term tolerance of equine spermatozoa to various abiotic factors

The aim of this study was to determine the effects of various abiotic factors, such as light, physical stress (pipetting) and thermal shock, on the quality of fresh and cooled equine sperm. In experiment I, four sperm aliquots were subjected to different light exposures: (i) protected control samples (CTRL), (ii) exposed to UV light at 10 cm (UV10), (iii) exposed to UV light at 20 cm (UV20) and (iv) exposed to laboratory lighting (LAB). In experiment II, four semen aliquots were subjected to repeated pipetting for 0, 10, 20 and 30 times (CTRL, P10, P20 and P30, respectively). In experiment III, four semen aliquots at 15°C were subjected to thermal oscillations: (i) cooled control sperm at 15°C (CTRL), (ii) oscillations of 1.9°C/min to a temperature of 30°C (T30), (iii) oscillations of 1.4°C/min, with the temperature rapidly falling until reaching 1.3°C (T0R) and (iv) oscillations of 1.1°C/min, with the temperature slowly falling until reaching 4.2°C (T0S). The results revealed that after 30 min, UV10 and UV20 sperm samples showed significantly (p < .05) lower total and progressive motility values, sperm kinematic parameters and mitochondrial potential. After 45 min of exposure, differences were highly significant (p < .001). No significant differences (p > .05) were found for pipetting or thermal oscillations. The results suggest that, even if equine sperm samples are not handled in the laboratory under optimal conditions, fresh and cooled equine spermatozoa are able to resist the impact of various abiotic stimuli without any reduction in their quality. This study analyses the effect on normospermic samples, but future research could look at the tolerance that asthenozoospermic equine samples have to these abiotic influences.