The seasonal abundance of the phototrophic ciliate Mesodinium rubrum in Southampton Water, England

The abundance of the marine phototrophic planktonic ciliateMesodinium rubrum was monitored throughout an annual cycle attwo stations in the Southampton Water estuary. Seasonal changesin the concentration of nitrate, ammonia and phosphate weremonitored both at the inner estuary station (NW Netley) andouter estuary station (Calshot). Nutrient levels in the winterwere similar at both stations, and were diminished during sequentialdiatom blooms dominated initially by Sketetonema costatum andthen by Rhizosolenia dclicatula. Nitrate was reduced to a seasonalminimum in the outer estuary following these spring diatom blooms,but in the inner estuary was sustained >500 µg I^–1until the onset of the M.rubrum bloom. During the developmentof a visible red tide of M.rubrum in June/July at NW Netley,nutrient concentrations were considerably reduced. Cell numbersof M.rubrum varied between 2 and 3 cells ml^– during winterto >400 cells ml^–1 during the bloom at NW Netley, whereasat Calshot cell abundance did not increase above 25 cells ml^–1at any time of the year. At NW Netley, dense accumulations ofthe ciliate occurred over restricted depth intervals duringthe bloom and possible factors influencing the observed verticaldistribution of cells are considered. ¹Present address: Biology Department, Faculty of Science, AddisAbaba University, PO Box 1176, Addis Ababa, Ethiopia     

Staphylococcus aureus in cow milk and milk products in Ambo and Bako towns,Oromia, Ethiopia: prevalence,associated risk factors,hygienic quality,and antibiogram

International Microbiology - Staphylococcus aureus (S. aureus) is a foodborne bacterial pathogens that can cause staphylococcal food poisoning and contaminate food of animal origin worldwide. The...     

Polymorphism in the HASPB Repeat Region of East African Leishmania donovani Strains

Background/Objectives

Visceral leishmaniasis (VL) caused by Leishmania donovani is a major health problem in Ethiopia. Parasites in disparate regions are transmitted by different vectors, and cluster in distinctive genotypes. Recently isolated strains from VL and HIV-VL co-infected patients in north and south Ethiopia were characterized as part of a longitudinal study on VL transmission.

Methodology/Principal Findings

Sixty-three L. donovani strains were examined by polymerase chain reaction (PCR) targeting three regions: internal transcribed spacer 1 (ITS1), cysteine protease B (cpb), and HASPB (k26). ITS1- and cpb - PCR identified these strains as L. donovani. Interestingly, the k26 - PCR amplicon size varied depending on the patient''s geographic origin. Most strains from northwestern Ethiopia (36/40) produced a 290 bp product with a minority (4/40) giving a 410 bp amplicon. All of the latter strains were isolated from patients with HIV-VL co-infections, while the former group contained both VL and HIV-VL co-infected patients. Almost all the strains (20/23) from southwestern Ethiopia produced a 450 bp amplicon with smaller products (290 or 360 bp) only observed for three strains. Sudanese strains produced amplicons identical (290 bp) to those found in northwestern Ethiopia; while Kenyan strains gave larger PCR products (500 and 650 bp). High-resolution melt (HRM) analysis distinguished the different PCR products. Sequence analysis showed that the k26 repeat region in L. donovani is comprised of polymorphic 13 and 14 amino acid motifs. The 13 amino acid peptide motifs, prevalent in L. donovani, are rare in L. infantum. The number and order of the repeats in L. donovani varies between geographic regions.

Conclusions/Significance

HASPB repeat region (k26) shows considerable polymorphism among L. donovani strains from different regions in East Africa. This should be taken into account when designing diagnostic assays and vaccines based on this antigen.     

Time to Death and Associated Factors among Tuberculosis Patients in Dangila Woreda,Northwest Ethiopia

Background

Tuberculosis (TB) is among the leading causes of morbidity and mortality worldwide. More than 70% of the deaths of TB patients occur during the first two months of TB treatment. The major risk factors that increase early death of TB patients are being positive for human immunodeficiency virus (HIV), being of old age, being underweight or undergoing re-treatment.

Objective

To assess the time of reported deaths and associated factors in a cohort of patients with TB during TB treatment.

Methods

An institution-based retrospective cohort study was analyzed in Dangila Woreda, Northwest Ethiopia from March 1^st through March 30, 2014. All TB patients registered in the direct observed treatment (DOTs) clinic from 2008–2012 were included in the study. Data were entered into EpiData and exported to SPSS for analysis. The survival probability was analyzed by the Kaplan Meier method and Cox regression analysis was applied to investigate factors associated with death during TB treatment.

Results

From a total of 872 cases registered in TB registry log book, 810 were used for the analysis of which 60 (7.4%) died during the treatment. The overall mortality rate was 12.8/1000 person months of observation. A majority of TB deaths 34 (56.7%) occurred during the intensive phase of the treatment, and the median time of death was at two months of the treatment. Age, HIV status and baseline body weight were independent predictors of death during TB treatment.

Conclusions

Most deaths occurred in the first two months of TB treatment. Old age, TB/HIV co-infection and a baseline body weight of <35 kg increased the mortality during TB treatment. Therefore, a special follow up of TB patients during the intensive phase, of older patients and of TB/HIV co-infected cases, as well as nutritionally supplementing for underweight patients may be important to consider as interventions to reduce deaths during TB treatment.     

Genetic Diversity and Population Structure of Ethiopian Chickpea (Cicer arietinum L.) Germplasm Accessions from Different Geographical Origins as Revealed by Microsatellite Markers

Genetic diversity and population structure were studied in 155 chickpea (Cicer arietinum L.) entries using 33 polymorphic microsatellite (SSR) markers. Molecular analysis of variance showed variations of 73% within and 27% among populations. Introduced genotypes exhibited highest polymorphism (70.27%) than the landraces (36?C57%). Collections from Shewa, Harerge, W. Gojam and S. Gonder regions also showed higher polymorphism (50?C57%) than the rest of the local accessions (36?C45%). Analyses of pairwise population Nei genetic distance and PhiPT coefficients, expected heterozygosity (He) and unbiased expected heterozygosity (UHe), Shannon??s information index (I) and percent polymorphism (% P) showed existence of high genetic variation between geographical regions. Accessions from adjoining geographical regions mostly showed more genetic similarities than those from origins far isolated apart. This could be associated with the ease and likelihood of inter-regional gene flow and seed movement particularly during times of drought. The 155 entries were grouped into five clusters following analysis of population structure. The first cluster (C₁) constituted accessions from Arsi; the second (C₂) from Gojam and Gonder; the third (C₃) from Harerge and E. and N. Shewa; and the fourth (C₄) from W. Shewa, Tigray, and Wello regions. The fifth cluster (C₅) was entirely consisted of improved genotypes. Improved genotypes of both Kabuli and Desi types distinctly fell into cluster five (C₅) regardless of their difference in seed types. The result has firmly established that introduction of genetic materials from exotic sources has broadened the genetic base of the national chickpea breeding program. Further implications of the findings as regards to chickpea germplasm management and its utilization in breeding program are also discussed.     

Diversity and compatibility of peanut (Arachis hypogaea L.) bradyrhizobia and their host plants

A high degree of genetic diversity among 125 peanut bradyrhizobial strains and among 32 peanut cultivars collected from different regions of China was revealed by using the amplified fragment length polymorphism (AFLP) technique. Eighteen different peanut bradyrhizobial genotypes and six peanut cultivars were selected for symbiotic cross-inoculation experiments. The genomic diversity was reflected in the symbiotic diversity. The peanut cultivars varied in their ability to nodulate with the strains used. Some cultivars had a more restricted host range than the others. Also the strains displayed a range of nodulation patterns. In yield formation there were clear differences between the plant cultivar/bradyrhizobium combinations. There was good compatibility between some peanut bradyrhizobial strains and selected cultivars, with inoculation resulting in well-nodulated, high-yielding symbiotic combinations, but no plant cultivar was compatible with all strains used. The strains displayed a varying degree of effectiveness, with some strains being fairly effective with all cultivars and others with selected ones. The AFLP genotypes of the strains did not explain the symbiotic behavior, whereas the yield formation of the plant cultivars was more related to the genotype. It is concluded that to obtain optimal nitrogen fixation efficiency of peanut in the field, compatible plant cultivar-bradyrhizobium combinations should be selected either by finding inoculant strains compatible with the plant cultivars used, or plant cultivars compatible with the indigenous bradyrhizobia.     

Performance of the parasitoid Aphidius colemani when reared on Myzus persicae on a fully defined artifical diet

Aphidius colemani Viereck(Hymenoptera: Aphidiidae) showed a developmenttime extended by 16% when reared on Myzus persicae Sulzer (Hemiptera: Aphididae) ofdifferent instars on artificial diet or onaphids on Brussels sprout plants. There wasalso a small but statistically significant 2%reduction in size (in hind tibia length) ofadult females. Rearing on diet had nosignificant effect on the number of eggsfemales contained at emergence. In a secondexperiment, aphids from Brussels sprouts ininstars 2–5 were compared with aphids from diettwo days older to give comparably sized aphidsfrom both substrates. Parasitisation by A.colemani gave the same direction of results,but showed that the effects in the firstexperiment were greater than predicted from thereduction in host size alone. However, in bothexperiments effects on parasitoids ofdiet-rearing the host were small, and culturingA. colemani on diet-reared aphids wassuccessful.     

Solid phase synthesis of a GHRP analog containing C-terminal thioamide group

[Lyst6]GHRP, the C-terminally thionated analog of the highly potent growth hormone releasing hexapeptide His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 was prepared by using solid support. The success of the synthesis showed that Lawesson's reagent can be used for selective thionation of an amide group not only in solution but also on the surface of a resin. The C-terminal thioamide group proved to be stable under the conditions of the solid phase synthesis.     

Evaluation of growth and biomass production of Arthrospira (Spirulina) fusiformis in laboratory cultures using waters from the Ethiopian soda lakes Chitu and Shala

The cost of nutrient media is the major challenge for biomass production of Spirulina. Although much effort has been made to use enriched seawater for the cultivation of this microalga, little attention has been given to the potential of water of soda lakes. In this study, growth (μ, day^?1) and biomass production (B) of Arthrospira fusiformis cultivated using waters of the soda lakes Chitu and Shala with or without supplementation were evaluated. Comparable μ and B values were achieved in both Lake Chitu water-based media (CBM) and Lake Shala water-based media (SBM), with slightly higher values in the latter. Both CBM and SBM supplemented with the standard Spirulina medium (SM) by 25 % and 50 % supported considerably higher μ and B. The pH and salinity of the cultures showed significant variations (P?μ and B. The observed higher μ and B were probably associated with the reduction in pH and salinity of the supplemented media due to addition of bicarbonate–carbonates and dilution, and provision of the limiting nutrient nitrogen. The higher μ and B in SBM may have resulted from some of their aggregate chemical parameters, which were closer to those in the SM, and abundant PO₄-P. This seems to suggest that Lake Shala water is more conducive to Arthrospira. We contend that 25 % and 50 % supplemented Lake Shala water can be preferably used to produce Arthrospira biomass, thereby reducing the cost of nutrients by 75 % and 50 %, respectively.