Isolation and characterization of high-efficiency Rhizobia from Western Kenya nodulating with common bean

Common bean is one of the primary protein sources in third-world countries. They form nodules with nitrogen-fixing rhizobia, which have to be adapted to the local soils. Commercial rhizobial strains such as Rhizobium tropici CIAT899 are often used in agriculture. However, this strain failed to significantly increase the common bean yield in many places, including Kenya, due to the local soils’ low pH. We isolated two indigenous rhizobial strains from the nodules of common bean from two fields in Western Kenya that have never been exposed to commercial inocula. We then determined their ability to fix nitrogen in common beans, solubilize phosphorus, and produce indole acetic acid. In greenhouse experiments, common bean plants inoculated with two isolates, B3 and S2 in sterile vermiculite, performed better than those inoculated with CIAT899 or plants grown with nitrogen fertilizer alone. In contrast to CIAT899, both isolates grew in the media with pH 4.8. Furthermore, isolate B3 had higher phosphate solubilization ability and produced more indole acetic acid than the other two rhizobia. Genome analyses revealed that B3 and S2 are different strains of Rhizobium phaseoli. We recommend fieldwork studies in Kenyan soils to test the efficacy of the two isolates in the natural environment in an effort to produce inoculants specific for these soils

Predominance of CCR5 tropism in non-b HIV-1 subtypes circulating in Kisii County, Kenya

Introduction: The chemokine receptors CCR5 and CXCR4 are considered as the main receptors during HIV infection, replication, transmission and subsequent AIDS progression. CCR5 antagonists are drugs designed to inhibit viral entry by binding to these chemokine receptors. However, characterisation of HIV-1 co-receptor usage before rolling out of CCR5/CXCR4 antagonists has not yet been done in the country.Objective: To determine the HIV-1 co receptor usage among HIV-1 infected individuals and predict possible use CCR5 antagonistic drugs.Design: A cross sectional study Setting: Comprehensive HIV care clinics of Kisii Teaching & Referral Hospital, Kenya.Methods: A total of seventy-two (72) blood samples were obtained from both drug naïve (32) and experienced (40) study participants. Viral DNA was extracted using QIAamp MinElute Virus kit and partial HIV-1 V3 region was amplified and directly sequenced. Coreceptor usage predicted using insilico Geno2pheno (coreceptor) with a false positive rate of 15%.Results: Sixty-one individuals (77.8%) were infected with HIV-1 subtype A1, twelve (18.1%) HIV-1 subtype D and four (4.1%) were HIV-1 subtype C. CCR5-using variants were found in 52 (72.2%) while 20(27.8%) participants were infected with CXCR4–using variants. There was no significant difference in co-receptor usage a cross gender, HIV subtypes, disease staging or impact of treatment or CD 4 counts that was observed.Conclusions and recommendation: The detected high level of circulating R5 strains suggests the likelihood of a successful implementation and use of CCR5 antagonists in Kenya where HIV-1 A1 is the most predominant

Rhizobia contribute to salinity tolerance in common beans (Phaseolus vulgaris L.)

Rhizobia are soil bacteria that induce nodule formation on leguminous plants. In the nodules, they reduce dinitrogen to ammonium that can be utilized by plants. Besides nitrogen fixation, rhizobia have other symbiotic functions in plants including phosphorus and iron mobilization and protection of the plants against various abiotic stresses including salinity. Worldwide, about 20% of cultivable and 33% of irrigation land is saline, and it is estimated that around 50% of the arable land will be saline by 2050. Salinity inhibits plant growth and development, results in senescence, and ultimately plant death. The purpose of this study was to investigate how rhizobia, isolated from Kenyan soils, relieve common beans from salinity stress. The yield loss of common bean plants, which were either not inoculated or inoculated with the commercial R. tropici rhizobia CIAT899 was reduced by 73% when the plants were exposed to 300 mM NaCl, while only 60% yield loss was observed after inoculation with a novel indigenous isolate from Kenyan soil, named S3. Expression profiles showed that genes involved in the transport of mineral ions (such as K+, Ca2+, Fe3+, PO43−, and NO3−) to the host plant, and for the synthesis and transport of osmotolerance molecules (soluble carbohydrates, amino acids, and nucleotides) are highly expressed in S3 bacteroids during salt stress than in the controls. Furthermore, genes for the synthesis and transport of glutathione and γ-aminobutyric acid were upregulated in salt-stressed and S3-inocculated common bean plants. We conclude that microbial osmolytes, mineral ions, and antioxidant molecules from rhizobia enhance salt tolerance in common beans

The Contribution of Healthcare Workers’ Knowledge on Use of Integrated Palliative Care Approach in the Management of Chronic and Life Threatening Diseases at Kakamega County Referral Hospital, Kenya

Integrated Palliative care approach (IPCA) is an approach that aims to improve the quality of life of people and their families facing the problems associated with life-threatening illness, through the prevention and relief of suffering. However, the use of IPCA in Kenya is low due to lack of access to medicines, technologies and infrastructure. The main objective was to investigate the use of IPCA in the management of chronic diseases at Kakamega County Referral Hospital (KCRH). The study design was a descriptive cross sectional with the quantitative approach. A questionnaire was administered to participants and the data analysis using SPSS. P-value was set at < 0.05. Of the total 196 Health Community Workers (HCWs) selected, a response rate of 95 % (186/196) was register. It showed that 50% males were less likely to have used IPCA as compared to their female counterparts (OR=0.5, 95% CI: 0.3-0.9) and 90% nurses were less likely to practice IPCA as compared to RCOs and MOs (OR=0.1, 95%CI: 0.1-0.5). The overall hypothesis test on the association between knowledge and performance was not significant (OR=1.6; 95% CI: 0.7 – 3.6, P<.2). The best managed symptoms by majority of respondents were severe diarrhea, anxiety and depression while the poorly managed areas were pain assessment and treatment of dyspnea. In conclusion, the HCWs were knowledgeable about IPCA but few utilized IPCA in managing terminal illnesses. Therefore, is a need to improve the HCWs’ skills and performance, increase funding, and improve infrastructure and coordination of use of IPCA

Distribution, characterization and the commercialization of elite Rhizobia strains in Africa

Grain legumes play a significant role in smallholder farming systems in Africa because of their contribution to nutrition and income security and their role in fixing nitrogen. Biological Nitrogen Fixation (BNF) serves a critical role in improving soil fertility for legumes. Although much research has been conducted on rhizobia in nitrogen fixation and their contribution to soil fertility, much less is known about the distribution and diversity of the bacteria strains in different areas of the world and which of the strains achieve optimal benefits for the host plants under specific soil and environmental conditions. This paper reviews the distribution, characterization, and commercialization of elite rhizobia strains in Africa

The Cell Membrane of a Novel Rhizobium phaseoli Strain Is the Crucial Target for Aluminium Toxicity and Tolerance

Soils with low pH and high aluminium (Al) contamination restrict common bean production, mainly due to adverse effects on rhizobia. We isolated a novel rhizobium strain, B3, from Kenyan soil which is more tolerant to Al stress than the widely used commercial strain CIAT899. B3 was resistant to 50 µM Al and recovered from 100 µM Al stress, while CIAT899 did not. Calcein labeling showed that less Al binds to the B3 membranes and less ATP and mScarlet-1 protein, a cytoplasmic marker, leaked out of B3 than CIAT899 cells in Al-containing media. Expression profiles showed that the primary targets of Al are genes involved in membrane biogenesis, metal ions binding and transport, carbohydrate, and amino acid metabolism and transport. The identified differentially expressed genes suggested that the intracellular γ-aminobutyric acid (GABA), glutathione (GSH), and amino acid levels, as well as the amount of the extracellular exopolysaccharide (EPS), might change during Al stress. Altered EPS levels could also influence biofilm formation. Therefore, these parameters were investigated in more detail. The GABA levels, extracellular EPS production, and biofilm formation increased, while GSH and amino acid level decreased. In conclusion, our comparative analysis identified genes that respond to Al stress in R. phaseoli . It appears that a large portion of the identified genes code for proteins stabilizing the plasma membrane. These genes might be helpful for future studies investigating the molecular basis of Al tolerance and the characterization of candidate rhizobial isolates that perform better in Al-contaminated soils than commercial strains

\u3cem\u3eRickettsia felis\u3c/em\u3e in Cat Fleas, \u3cem\u3eCtenocephalides felis\u3c/em\u3e Parasitizing Opossums, San Bernardino County, California

Los Angeles and Orange Counties are known endemic areas for murine typhus in California; however, no recent reports of flea-borne rickettsioses are known from adjacent San Bernardino County. Sixty-five opossums (Didelphis virginiana) were trapped in the suburban residential and industrial zones of the southwestern part of San Bernardino County in 2007. Sixty out of 65 opossums were infested with fleas, primarily cat fleas, Ctenocephalides felis (Bouché, 1835). The flea minimum infection rate with Rickettsia felis was 13.3% in pooled samples and the prevalence was 23.7% in single fleas, with two gltA genotypes detected. In spite of historic records of murine typhus in this area, no evidence for circulation of R. typhi in fleas was found during the present study. Factors contributing to the absence of R. typhi in these cat fleas in contrast to its presence in cat fleas from Orange and Los Angeles Counties are unknown and need to be investigated further in San Bernardino County

Olfactory and solitary chemosensory cells: two different chemosensory systems in the nasal cavity of the American alligator, Alligator mississippiensis

<p>Abstract</p> <p>Background</p> <p>The nasal cavity of all vertebrates houses multiple chemosensors, either innervated by the Ist (olfactory) or the Vth (trigeminal) cranial nerve. Various types of receptor cells are present, either segregated in different compartments (e.g. in rodents) or mingled in one epithelium (e.g. fish). In addition, solitary chemosensory cells have been reported for several species. Alligators which seek their prey both above and under water have only one nasal compartment. Information about their olfactory epithelium is limited. Since alligators seem to detect both volatile and water-soluble odour cues, I tested whether different sensory cell types are present in the olfactory epithelium.</p> <p>Results</p> <p>Electron microscopy and immunocytochemistry were used to examine the sensory epithelium of the nasal cavity of the American alligator. Almost the entire nasal cavity is lined with olfactory (sensory) epithelium. Two types of olfactory sensory neurons are present. Both types bear cilia as well as microvilli at their apical endings and express the typical markers for olfactory neurons. The density of these olfactory neurons varies along the nasal cavity. In addition, solitary chemosensory cells innervated by trigeminal nerve fibres, are intermingled with olfactory sensory neurons. Solitary chemosensory cells express components of the PLC-transduction cascade found in solitary chemosensory cells in rodents.</p> <p>Conclusion</p> <p>The nasal cavity of the American alligator contains two different chemosensory systems incorporated in the same sensory epithelium: the olfactory system proper and solitary chemosensory cells. The olfactory system contains two morphological distinct types of ciliated olfactory receptor neurons.</p

Cell specific microvesicles vary with season and disease predisposition in healthy and previously laminitic ponies

Microvesicles are small (up to 1 μm) vesicles found in plasma and other bodily fluids. They are recognised as part of the normal system of inter-cellular communication but altered numbers are also used as biomarkers of disease. Microvesicles have not been studied in detail in the horse but may be relevant to diseases such as laminitis. Identification of equine cell specific microvesicles was performed by developing a panel of cross reactive antibodies to use in flow cytometry to detect microvesicles of platelet, leucocyte and endothelial origin in plasma from healthy ponies and those predisposed to laminitis. The total number and proportion of microvesicles from the different cell types varied with season and there were more annexin V positive endothelial MV in non laminitic ponies compared to previously laminitic ponies. Development of this antibody panel and the technique for measuring microvesicles in the horse opens a new field for further investigation of these important structures in equine health and disease

A hierarchical network approach for modeling Rift Valley fever epidemics with applications in North America

Rift Valley fever is a vector-borne zoonotic disease which causes high morbidity and mortality in livestock. In the event Rift Valley fever virus is introduced to the United States or other non-endemic areas, understanding the potential patterns of spread and the areas at risk based on disease vectors and hosts will be vital for developing mitigation strategies. Presented here is a general network-based mathematical model of Rift Valley fever. Given a lack of empirical data on disease vector species and their vector competence, this discrete time epidemic model uses stochastic parameters following several PERT distributions to model the dynamic interactions between hosts and likely North American mosquito vectors in dispersed geographic areas. Spatial effects and climate factors are also addressed in the model. The model is applied to a large directed asymmetric network of 3,621 nodes based on actual farms to examine a hypothetical introduction to some counties of Texas, an important ranching area in the United States of America (U.S.A.). The nodes of the networks represent livestock farms, livestock markets, and feedlots, and the links represent cattle movements and mosquito diffusion between different nodes. Cattle and mosquito (Aedes and Culex) populations are treated with different contact networks to assess virus propagation. Rift Valley fever virus spread is assessed under various initial infection conditions (infected mosquito eggs, adults or cattle). A surprising trend is fewer initial infectious organisms result in a longer delay before a larger and more prolonged outbreak. The delay is likely caused by a lack of herd immunity while the infections expands geographically before becoming an epidemic involving many dispersed farms and animals almost simultaneously