Pharmacodynamics of amoxicillin against field isolates of Streptococcus parauberis from olive flounder (Paralichthys olivaceus)

Olive flounder is the most important species for the Northeast Asian fish farming industry. However, this species is substantially affected by multiple infectious agents, including Streptococcus parauberis. Evaluation of antibiotics before their application is critical to treat infections and prevent drug resistance. Therefore, in this study, the pharmacodynamics of amoxicillin (AMX) and other antimicrobials against the planktonic‐ and biofilm‐forming bacteria were assessed. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and Time–kill curve assay were analysed using micro‐dilution method. The minimum biofilm eradicating concentration (MBEC) was determined using the Calgary Biofilm device. The effects of temperature, pH, hardness and salinity were detected for both planktonic‐ and biofilm‐forming bacteria. The MIC of AMX ranged from 0.015 to 2 μg/ml, whereas that of cephalexin (CEP), enrofloxacin (ENR) and oxytetracycline (OTC) ranged from 0.125 to 256, 0.125 to >512 and 0.25 to >512 μg/ml respectively. No bacteria were resistant against AMX, while the percentage of resistance to CEP, OTC and ENR were 68.7%, 52.6% and 11.1% respectively. The IC₅₀ of AMX, CEP, ENR and OTC was 0.03, 0.091, 0.015 and 0.213 μg/ml respectively. The MBEC of amoxicillin against S. parauberis ranged from 0.5 to 16 μg/ml. Higher rates of bacterial growth were obtained at 30°C, pH = 8 and salinity of 7.5–10 ppt. The hardness of the media suppressed the bacterial growth. In conclusion, AMX was found to be effective against both the planktonic and the biofilm forms of the prominent fish pathogen, S. parauberis.     

Genetic diversity analysis of advanced chickpea (Cicer arietinum L.) genotypes in Ethiopia for identification of high-yielding and novel Fusarium wilt resistance sources

Journal of Crop Science and Biotechnology - Chickpea (Cicer arietinum L.) is one of the most important food legumes in the world. However, Fusarium wilt is one of the major yield limiting factors...     

Expression of Toll-like receptors and downstream genes in lipopolysaccharide-induced porcine alveolar macrophages

The aim of the present study was to determine the age-related kinetic changes of Toll-like receptors (TLRs) and downstream genes expression, and secretion of cytokine in lipopolysaccharide (LPS) stimulated porcine alveolar macrophages (AM). For this purpose, AMs were isolated from 5-day-old newborn piglets and 120-day-old young pigs. mRNA expression and cytokine measurement was determined by quantitative real-time PCR and ELISA, respectively. First, AMs were incubated for 24 h in the absence or presence of increasing concentrations of LPS. Results showed the up-regulation of TLRs 2, 4, 5 and 9 mRNA from all concentrations of LPS used, as compared to non-stimulated cells, and TLR4 was the highest expression in both ages (P<0.05). Furthermore, quantitative analysis demonstrated increased expression of mRNAs encoding TLRs 2, 4, 5 and 9, LBP, CD14, MD2, MyD88, IRAK4 and TRAF6 in both ages in a time-dependant manner (P<0.05). Overall, LPS inducible mRNA for TLR4, LBP, CD14 and MyD88 had higher expression in newborn piglets compared with those of young pigs (P<0.05). The level of cytokine protein IL6 and TNFα in supernatant fluid significantly varied with time of incubation and age of animals. Their concentration increased immediately at 1 h after LPS stimulation and remained significantly higher up to 48 h in both ages. Production of pro-inflammatory cytokine protein IL6 and TNFα in supernatant was significantly higher in young pigs than those of piglets. This study suggests that differential age-related changes in the expression of TLRs and downstream genes, and pro-inflammatory cytokine could contribute to a different age-related innate immune response during pulmonary infection. Further investigation is warranted to determine the precise effects of LPS on porcine AMs by means of a functional study across a wider age range.     

Diversity of bacterial species in the nasal cavity of sheep in the highlands of Ethiopia and first report of Histophilus somni in the country

A study was conducted to isolate bacterial species/pathogens from the nasal cavity of apparently healthy and pneumonic sheep. Nasal swabs were collected aseptically, transported in tryptose soya broth and incubated for 24 h. Then, each swab was streaked onto chocolate and blood agar for culture. Bacterial species were identified following standard bacteriological procedures. Accordingly, a total of 1,556 bacteria were isolated from 960 nasal swabs collected from three different highland areas of Ethiopia, namely Debre Berhan, Asella, and Gimba. In Debre Berhan, 140 Mannheimia haemolytica, 81 Histophilus somni, 57 Staphylococcus species, and 52 Bibersteinia trehalosi were isolated. While from Gimba M. haemolytica, Staphylococcus, Streptococcus, and H. somni were isolated at rates of 25.2, 15.9, 11.4, and 5.9 %, respectively, of the total 647 bacterial species. In Asella from 352 bacterial species isolated, 93 (26.4 %) were M. haemolytica, 48 (13.6 %) were Staphylococcus species, 26 (7.4 %) were B. trehalosi, and 17 (4.8 %) H. somni were recognized. Further identification and characterization using BIOLOG identification system Enterococcus avium and Sphingomonas sanguinis were identified at 100 % probability, while, H. somni and Actinobacillus lignerisii were suggested by the system. The study showed that a variety of bacterial species colonize the nasal cavity of the Ethiopian highland sheep with variable proportion between healthy and pneumonic ones. To our knowledge, this is the first report on isolation of H. somni, an important pathogen in cattle, from the respiratory tract of a ruminant species in the country.     

Performance Evaluation of Malt Barley: from Malting Quality and Breeding Perspective

Lack of suitable malt barley varieties that exhibit high yielding, stable performance, and good malting quality is the major factor among several production constraints contributing to low productivity of malt barley in the North Gondar Zone. The present study was done to evaluate and recommend the best performing varieties in the major potential areas of North Gondar. The experiment was conducted at three locations for two consecutive years (2015 and 2016) during the main cropping season using twelve improved varieties. The design was randomized complete block design with three replications. Analysis of variance and GGE [genotype main effect (G) and genotype-by-environment interaction (GE)] biplot analysis were conducted following their respective procedures. Combined analysis of variance revealed a highly significant difference (P < 0.01) among genotypes, environments, and genotype-by-environment interaction for grain yield, most agronomic and malt quality traits. All the varieties had acceptable malt quality traits. The variety IBON-174/03 was found to be the highest yielding and the most stable variety across environments. According to the polygon view of biplot analysis, the varieties were spread across four sections and the test environments spread across two sections. Among the six test environments, D and C were more discriminating and F and B were less discriminating. Test environments F, E, and A were found to be more representative of the mega-environment than D. Considering early maturity, malt quality, grain yield, and stability performance; it is recommended to use the variety IBON-174/03 for production in the study areas and in similar areas.     

Genotype X environment interaction and stability analysis in upland rice (Oryza sativa L.) varieties in Ethiopia

Journal of Crop Science and Biotechnology - Determination of the genotype x environment interaction (GEI) and stability of upland rice varieties for grain yield provides the basis to identify...     

Sorghum protein digestibility is affected by dosage of mutant alleles in endosperm cells

Protein digestibility in grain sorghum (Sorghum bicolor (L.) Moench) is affected by the structure of endosperm protein bodies that limits access of digestive enzymes to storage protein. In this experiment, we studied the effect of endosperm dosage of high digestible alleles (hd⁺) on protein digestibility in sorghum hybrids carefully constituted for such a study. We also examined the effect that these alleles may have on endosperm protein body structure and agronomic performance of the hybrids. The results showed that protein digestibility, endosperm texture and protein body morphology were highly influenced by dosage of mutant alleles. Genotypes carrying two or more hd⁺ alleles had significantly higher protein digestibility than those with one or no mutant allele. Similarly, higher doses of these alleles resulted in opaque endosperm phenotype while the wild type alleles produced normal vitreous texture. Moreover, hybrids carrying variable proportions of mutant alleles had uniquely irregular but variable protein body structure that was distinct from spherical protein bodies found in normal genotypes. Agronomic performance was not affected by dosage of digestibility alleles.     

The impact of small-scale irrigation on household food security: The case of Filtino and Godino irrigation schemes in Ethiopia

Ethiopia’s irrigation potential is estimated at 3.7 million hectare, of which only about 190,000 ha (4.3% of the potential) is actually irrigated. There is little information on the extent to which the so far developed irrigation schemes have been effective in meeting their stated objectives of attaining food self-sufficiency and eradicating poverty. Therefore, the aim of this paper is to identify the impact of small-scale irrigation on household food security based on data obtained from 200 farmers in Ada Liben district of Ethiopia in 2006. The resulting data was analyzed using Heckman’s Two-step Estimation procedure. Studies elsewhere revealed that access to reliable irrigation water can enable farmers to adopt new technologies and intensify cultivation, leading to increased productivity, overall higher production, and greater returns from farming. Our study findings confirm some of these claims. In the study area about 70% of the irrigation users are food secure while only 20% of the non-users are found to be food secure. Access to small scale irrigation enabled the sample households to grow crops more than once a year; to insure increased and stable production, income and consumption; and improve their food security status. The study concludes that small-scale irrigation significantly contributed to household food security.

Stalk strength and reaction to infection by Macrophomina phaseolina of brown midrib maize (Zea mays) and sorghum (Sorghum bicolor)

Reduced lignin concentration in brown mid-rib mutants in both maize and sorghum have resulted in improved dry matter digestibility, increased milk yield and higher energy in lactating cows. However, the mutations were not widely deployed due to concern that reduced lignin concentration might increase vulnerability to lodging and stalk rot incidence. The objective of this study was to determine the effects of the mutations on stalk strength and stalk rot resistance in both sorghum and maize. Six brown midrib (bmr) sorghum, four brown midrib (bm) maize, and their normal isolines were evaluated for stalk strength and stalk rot disease reaction at two locations in four replications. Three randomly selected plants in each plot were inoculated with Macrophomina phaseolina at 14 d after flowering by using the toothpick inoculation technique. On 28 d after inoculation, the plants were rated for disease severity by measuring the length of necrotic lesions in the stalks. Stalk strength was determined from another three random plants in each plot by using a rind penetrometer. The mutations had no effect on stalk rot disease severity in either sorghum or maize though stalks strength was markedly affected by the mutations in both species. While maize bm entries broke easily in response to mild mechanical stress, bmr sorghums did not exhibit sign of stalk collapse in all backgrounds. The result suggests that the bmr genes in both maize and sorghum can be deployed without incurring losses to stalk rot disease.