Temporal relationship between climate variability, Prosopis juliflora invasion and livestock numbers in the drylands of Magadi, Kenya

A study was conducted to determine the association of climate variability, Prosopis juliflora spread, and other vegetation trends with livestock population dynamics in Kajiado County, Kenya. Monthly rainfall, mean monthly temperatures, cattle, sheep and goats populations from January 2000 to December 2014, were analyzed to determine time series trends. Normalized Difference Vegetation Index (NDVI) data derived from moderate resolution imaging spectroradiometer (MODIS) 250 m satellite imageries for 2000 to 2014 were used to determine the temporal dynamics of P. juliflora invasion in the study area. Both temperature and rainfall trends showed marked variability over the period under study. The mean monthly temperatures during the long dry season increased erratically from 33°C in 2000 to 37°C in 2014. Moreover, the rainfall during the wettest season was 600 mm in 2000 and 250 mm in 2014. During the study period, divergence from the long term mean rainfall (450 mm) decreased from 585 to 403 mm. At the same time cattle population decreased, sheep and goats populations remained static. P. juliflora invasion correlated positively (r=0.2; P<0.05) with mean monthly temperature and negatively (r=-0.4; P<0.05) with rainfall and other vegetation cover in drier parts, but not in the higher altitude and wetter parts of the study area. It also correlated negatively with cattle populations (r=-0.4; P<0.05). In the 1980’s, bushlands and woodlands constituted 95 and 5% of the land cover, while in 2008, herbaceous vegetation, shrublands, and open trees together with bare areas constituted 50, 30, and 22%, respectively; out of which 70% had been taken over by Prosopis in 2014. This study demonstrated that even though the trends showed that cattle population decreased as climate variability and Prosopis invasion increased, there was no significant correlation among the attributes, over the period under study.Key words: Climate, drylands, livestock, Prosopis juliflora, variability vegetation, trends, mesquite

The use of a P. falciparum specific coiled-coil domain to construct a self-assembling protein nanoparticle vaccine to prevent malaria.

The parasitic disease malaria remains a major global public health concern and no truly effective vaccine exists. One approach to the development of a malaria vaccine is to target the asexual blood stage that results in clinical symptoms. Most attempts have failed. New antigens such as P27A and P27 have emerged as potential new vaccine candidates. Multiple studies have demonstrated that antigens are more immunogenic and are better correlated with protection when presented on particulate delivery systems. One such particulate delivery system is the self-assembling protein nanoparticle (SAPN) that relies on coiled-coil domains of proteins to form stable nanoparticles. In the past we have used de novo designed amino acid domains to drive the formation of the coiled-coil scaffolds which present the antigenic epitopes on the particle surface. Here we use naturally occurring domains found in the tex1 protein to form the coiled-coil scaffolding of the nanoparticle. Thus, by engineering P27A and a new extended form of the coiled-coil domain P27 onto the N and C terminus of the SAPN protein monomer we have developed a particulate delivery system that effectively displays both antigens on a single particle that uses malaria tex1 sequences to form the nanoparticle scaffold. These particles are immunogenic in a murine model and induce immune responses similar to the ones observed in seropositive individuals in malaria endemic regions. We demonstrate that our P27/P27A-SAPNs induce an immune response akin to the one in seropositive individuals in Burkina Faso. Since P27 is highly conserved among different Plasmodium species, these novel SAPNs may even provide cross-protection between Plasmodium falciparum and Plasmodium vivax the two major human malaria pathogens. As the SAPNs are also easy to manufacture and store they can be delivered to the population in need without complication thus providing a low cost malaria vaccine

MscS-like mechanosensitive channels in plants and microbes

The challenge of osmotic stress is something all living organisms must face as a result of environmental dynamics. Over the past three decades, innovative research and cooperation across disciplines have irrefutably established that cells utilize mechanically gated ion channels to release osmolytes and prevent cell lysis during hypoosmotic stress. Early electrophysiological analysis of the inner membrane of Escherichia coli identified the presence of three distinct mechanosensitive activities. The subsequent discoveries of the genes responsible for two of these activities, the mechanosensitive channels of large (MscL) and small (MscS) conductance, led to the identification of two diverse families of mechanosensitive channels. The latter of these two families, the MscS family, consists of members from bacteria, archaea, fungi, and plants. Genetic and electrophysiological analysis of these family members has provided insight into how organisms use mechanosensitive channels for osmotic regulation in response to changing environmental and developmental circumstances. Furthermore, determining the crystal structure of E. coli MscS and several homologues in several conformational states has contributed to our understanding of the gating mechanisms of these channels. Here we summarize our current knowledge of MscS homologues from all three domains of life and address their structure, proposed physiological functions, electrophysiological behaviors, and topological diversity

Total Mixed Rations Verses Traditional Feeding of Dairy Cows: Which way to go?

No abstract The Kenya Veterinarian Vol. 21 2001: pp. 12-1

An account of a recent outbreak of Marek\'s Disease in Kenya

Data was collected from a number of flocks following an outbreak of Marek's disease in Thika, Kiambu and Nairobi, in 1997. Clinically, the disease presented as a rapid emaciation and depression followed by death. Weekly point and cumulative mortalities were calculated in two of the flocks. Postmortem examination revealed, initially, an atrophy of the bursa of Fabricious. Later, there were turmours in a proportion of the birds. The tumours were observed in the heart muscle, the liver, intestines, and bursa of fabricious. Later, there were tumours in a proportion of birds. The tumours were observed in heart muscles, the liver, intestines, bursa of Fabricious and the skin. There was swelling, oedema and frequently ulceration of the proventriculus. The spleen was usually spotted and enlarged. Microscopically, lesions consisted of a mixture of both proliferative and necrotic lesions the suspected contributory causative factors were high field infections pressure, failure to vaccinate, vaccination failure and lack of quarantine and other disease control measures. Failure to institute effective control measures against the disease is likely to seriously affect the poultry industry in the country. The Kenya Veterinarian Vol. 21 2001: pp. 34-3

Trichophycin A, a Cytotoxic Linear Polyketide Isolated from a Trichodesmium thiebautii Bloom

In an effort to isolate and characterize bioactive secondary metabolites from Trichodesmium thiebautii blooms, collected cyanobacteria biomass was subjected to bioassay-guided extraction and fractionation using the human colon cancer cell line HCT-116, resulting in the isolation and subsequent structure characterization of a linear polyketide trichophycin A (1). The planar structure of 1 was completed using 1D and 2D NMR spectroscopy and high-resolution electrospray ionization mass spectrometry (HRESIMS). Trichophycin A was moderately toxic against the murine neuroblastoma cell line Neuro-2A (EC50: 6.5 μM) and HCT-116 cells (EC50: 11.7 μM). Trichophycin A was significantly more cytotoxic than the previously isolated polyketides trichotoxin A and trichotoxin B. These cytotoxicity observations suggest that toxicity may be related to the polyol character of these polyketide compounds

An Investigation into a Human Anthrax Outbreak in Maragua District, Central Kenya

An outbreak of human anthrax occurred in Maragua district between December 2005 and January 2006 and an investigation was undertaken through visits and interviews with the District Veterinary (DVO) and Public Health Officers, owners of cattle that had died, people who had butchered or eaten the meat from dead animals and patients who had been affected by the disease. It was found that 514 out of 700 people had eaten the affected meat but only 30 got clinical disease, one (1) of which was enteric and the rest twenty nine (29) were cutaneous. The attack rate appeared to have been greatly reduced by the practice of repeatedly boiling the meat and discarding the soup before eating the meat. The disease outbreak in cattle was associated with low vaccination rates of cattle against anthrax in the area, human movement, poor handling of the infected meat, and activities of scavenging dogs and chickens and possibly insects. Ignorance, retrogressive socio-cultural practices and poor socio-economic conditions were risk factors that contributed to the outbreak of the disease in humans. Kenya Veterinarian Vol. 30 (2) 2006: pp. 62-6