Abstract: Plant litter breakdown is a key ecological process in terres- trial and freshwater ecosystems. Streams and rivers, in particular, contribute substantially to global carbon fluxes. However, there is little information available on the relative roles of different drivers of plant litter break- down in fresh waters, particularly at large scales. We present a global-scale study of litter breakdown in streams to compare the roles of biotic, climatic and other environ- mental factors on breakdown rates. We conducted an experiment in 24 streams encompassing latitudes from 47.88 N to 42.88 S, using litter mixtures of local species dif- fering in quality and phylogenetic diversity (PD), and alder (Alnus glutinosa) to control for variation in litter traits. Our models revealed that breakdown of alder was driven by climate, with some influence of pH, whereas variation in breakdown of litter mixtures was explained mainly by litter quality and PD. Effects of litter quality and PD and stream pH were more positive at higher temp- eratures, indicating that different mechanisms may operate at different latitudes. These results reflect global variability caused by multiple factors, but unexplained variance points to the need for expanded global-scale comparisons.

Abstract: Purpose – Contract farming (CF) is seen as a tool for creating new market opportunities hence increasing incomes for smallholder farmers. Critics, however, argue that CF is likely to pass risks to small scale farmers, thus favouring large scale farmers at the expense of smallholder farmers. The purpose of this paper is to examine the effect of CF on smallholder farmers’ income using a case study of avocado farmers in Kandara district in Kenya. Design/methodology/approach – The study uses data collected from 100 smallholder avocado farmers in Kandara district in Kenya and employs an instrumental variable model (Probit-2SLS) to control for endogeneity in participation in the contract and examine the effect of CF on household, farm and avocado income. Findings – The results indicate that participation in CF is not sufficient to improve household, farm and avocado income. Question remains regarding efficient implementation of CF arrangements to promote spill over effects on other household enterprises. Resear...

Abstract: Forests in Kenya are threatened by unsustainable uses and conversion to alternative land uses. In spite of the consequences of forest degradation and biodiversity loss and reliance of communities on forests livelihoods, there is little empirical data on the role of forest resources in livelihoods of the local communities. Socioeconomic, demographic, and forest use data were obtained by interviewing 367 households. Forest product market survey was undertaken to determine prices of various forest products for valuation of forest use. Forest income was significant to households contributing 33% of total household income. Fuel wood contributed 50%, food (27%), construction material (18%), and fodder, and thatching material 5% to household forest income. Absolute forest income and relative forest income (%) were not significantly different across study locations and between ethnic groups. However, absolute forest income and relative forest income (%) were significantly different among wealth classes. Poor households were more dependent on forests resources. However, in absolute terms, the rich households derived higher forest income. These results provide valuable information on the role of forest resources to livelihoods and could be applied in developing forest conservation policies for enhanced ecosystem services and livelihoods.

Abstract: In this study, a polyethylene (PE) packaging material that contained nano-Ag, nano-TiO2, nano-SiO2, and attapulgite was prepared and its effect on storage stability of mushrooms (Flammulina velutipes) was investigated. The results showed that the nanocomposite-based packaging material (Nano-PM) regulated oxygen and carbon dioxide level, eliminated ethylene and inhibited the growth of microbes, which is a benefit on preservation quality of mushrooms, compared to the normal PE material (Normal-PM). After 14 days of storage, mushroom weight loss, mushroom cap opening, stipe elongation and respiration of Nano-PM stored mushroom were significantly (P Industrial relevance Flammulina velutipes, also named as golden needle mushroom, is one of the most popular edible mushrooms worldwide. Its production and consumption ranked the fourth place among all edible mushrooms in the world. However, fresh golden needle mushrooms are highly perishable. Therefore, preserving freshness of the mushrooms is the main objective of postharvest technology. In the present study, we developed a new type of effective and economic nanoparticle packaging materials and applied it to mushroom preservation. A local company (Jiangsu Tianfeng Biological Technology Co., Ltd) producing mushrooms has started to use this nano-preservation technology during the postharvest transportation and sales. In conjunction with the results of present research, we suggests that nano-composite based packaging materials is a good way for preserving fresh mushrooms and has the potential to be commercialized.

Abstract: We investigated the antifungal properties and anti-candidal mechanism of antimicrobial peptide APP. The minimum inhibitory concentration of APP was 8 μM against Candida albicans and Aspeogillus flavus, the concentration against Saccharomyces cerevisiae and Cryptococcus neoformans was 16 μM, while 32 μM inhibited Aspergilla niger and Trichopyton rubrum. APP caused slight depolarization (12.32 ± 0.87%) of the membrane potential of intact C. albicans cells when it exerted its anti-candidal activity and only caused 21.52 ± 0.48% C. albicans cell membrane damage. APP interacted with cell wall membrane, caused potassium efflux and nucleotide leakage. However, confocal fluorescence microscopy experiment and flow cytometry confirmed that FITC-labeled APP penetrated C. albicans cell membrane with 52.31 ± 1.88% cell-penetrating efficiency and accumulated in the cytoplasm. Then, APP interact with C. albicans genomic DNA and completely suppressed DNA migration above weight ratio (peptide/DNA) of 2, and significantly arrested cell cycles during the S-phase (S-phase cell population was 27.09 ± 0.73%, p < 0.05) after penetrating the cell membrane. Results indicated that APP kills C. albicans for efficient cell-penetrating efficiency, strong DNA-binding affinity and significant physiological changes inducing S-phase arrest in intracellular environment.

Abstract: The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemesio 2007; Donegan 2008, 2009; Nemesio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016.

Abstract: Chinese licorice, (Glycyrrhiza uralensis Fisch.) is one of the commonly prescribed herbs in Traditional Chinese Medicine (TCM). Gancao, as commonly known in China, is associated with immune-modulating and anti-tumor potential though the mechanism of action is not well known. In this study, we investigated the in vitro immunomodulatory and antitumor potential of Glycyrrhiza uralensis polysaccharides fractions of high molecular weight (fraction A), low molecular weight (fraction B) and crude extract (fraction C). Cell proliferation and cytotoxicity was investigated using Cell Counting kit 8 (CCK-8) on Intestinal epithelial cell line (IEC-6) and Colon carcinoma cell line (CT-26). IL-7 gene expression relative to GAPDH was analysed using Real time PCR. The stimulation and viability of T lymphocytes was determined by Trypan blue exclusion assay. G.uralensis polysaccharides did not inhibit proliferation of IEC-6 cells even at high concentration. The ED50 was found to be 100 μg/ml. On the other hand, the polysaccharides inhibited the proliferation of cancer cells (CT-26) at a concentration of ≤50 μg/ml. Within 72 h of treatment with the polysaccharides, expression of IL-7 gene was up-regulated over 2 times. It was also noted that, IEC-6 cells secrete IL-7 cytokine into media when treated with G.uralensis polysaccharides. The secreted IL-7 stimulated proliferation of freshly isolated T lymphocytes within 6 h. The effect of the polysaccharides were found to be molecular weight depended, with low molecular weight having a profound effect compared to high molecular weight and total crude extract. Our findings indicate that G.uralensis polysaccharides especially those of low molecular weight have a potential as anticancer agents. Of great importance, is the ability of the polysaccharides to up-regulate anticancer cytokine IL-7, which is important in proliferation and maturation of immune cells and it is associated with better prognosis in cancer. Therefore, immunomodulation is a possible mode of action of the polysaccharides in cancer therapy.

Abstract: This study assessed provisioning and cultural ecosystem services (ES) provided by natural wetlands and rice fields in two Kenyan wetlands; Ombeyi natural wetland and rice fields in Kore Irrigation Scheme. Data was collected through household questionnaire survey of 151 randomly selected farmers and 1 focus group discussion. The provisioning ES assessed included fibre; papyrus mats, reeds and thatching grass; fish and rice while cultural ES were religious/spiritual, eco-tourism, educational excursions and recreational use. The provisioning ES were quantified in terms of biophysical quantities and monetary value while cultural ES were graded per level of utilisation as low, medium and high. The study revealed that rice fields have enhanced food production (rice) in the area in addition to their higher value in terms of provisioning ES; rice (USD 602.49) and fish (USD 1039.50), and cultural ES (religious/spiritual and recreational use). In the natural wetland, both provisioning and cultural ES have declined over the past 20 years. The annual monetary value of USD 397.40 and 683.50 were observed for papyrus mats and fish production respectively in the natural wetland. Although rice fields seem to have higher value compared to the natural wetland sustainable utilisation of both systems is crucial in enhancing livelihoods.

Abstract: Participatory on-farm trials were conducted to assess effectiveness of Purdue Improved Crop Storage (PICS™) bags for storage of maize in small-scale farmers’ stores in rural villages in eastern Kenya. A PICS bag is a three-layered hermetic bag-system that forms a barrier against the influx of oxygen and the escape of carbon dioxide. Jute, woven polypropylene or PICS bags were filled with shelled maize grain, purchased from the participating farmers, and the three sets of bags kept in the farmers’ own stores for 35 weeks. Oxygen and carbon dioxide levels in the PICS bags were monitored, as well as the temperature and relative humidity in all the bags. Grain moisture, live insect population, grain damage and weight loss were examined at intervals of seven weeks. Oxygen and carbon dioxide composition demonstrated that PICS bags are capable of sustaining good air-barrier properties under farmer storage conditions. Moreover, moisture content of maize stored in PICS bags did not change throughout the storage period whereas the moisture content of maize stored in polypropylene and jute bags decreased significantly in the final 14 weeks. Maize stored in PICS bags remained free from insect infestation and the weight loss due to insect damage was below 1 %. On the contrary, polypropylene and jute bags permitted profuse build-up of insect populations. At 35 weeks, grain damage reached 77.6 % and 82.3 % corresponding to 41.2 % and 48.5 % weight loss in the polypropylene and jute bags respectively. These findings demonstrate that PICS bags are effective in controlling losses caused by storage pests under farmer storage conditions.

Abstract: For decades, odour-baited traps have been used for control of tsetse flies (Diptera; Glossinidae), vectors of African trypanosomes. However, differential responses to known attractants have been reported in different Glossina species, hindering establishment of a universal vector control tool. Availability of full genome sequences of five Glossina species offers an opportunity to compare their chemosensory repertoire and enhance our understanding of their biology in relation to chemosensation. Here, we identified and annotated the major chemosensory gene families in Glossina. We identified a total of 118, 115, 124, and 123 chemosensory genes in Glossina austeni, G. brevipalpis, G. f. fuscipes, G. pallidipes, respectively, relative to 127 reported in G. m. morsitans. Our results show that tsetse fly genomes have fewer chemosensory genes when compared to other dipterans such as Musca domestica (n>393), Drosophila melanogaster (n = 246) and Anopheles gambiae (n>247). We also found that Glossina chemosensory genes are dispersed across distantly located scaffolds in their respective genomes, in contrast to other insects like D. melanogaster whose genes occur in clusters. Further, Glossina appears to be devoid of sugar receptors and to have expanded CO2 associated receptors, potentially reflecting Glossina's obligate hematophagy and the need to detect hosts that may be out of sight. We also identified, in all species, homologs of Ir84a; a Drosophila-specific ionotropic receptor that promotes male courtship suggesting that this is a conserved trait in tsetse flies. Notably, our selection analysis revealed that a total of four gene loci (Gr21a, GluRIIA, Gr28b, and Obp83a) were under positive selection, which confers fitness advantage to species. These findings provide a platform for studies to further define the language of communication of tsetse with their environment, and influence development of novel approaches for control.

Abstract: INTRODUCTION: training, as an additive human resources intervention is decisive to organizational performance. Employees require constant update of formal and informal knowledge alongside positive attitudes that have been defined as necessary in motivation leading to effectiveness in performance hence workplace training is tied to achieving organizational aims and objectives. The objective of this study was to determine the influence of training on motivation among health workers in Narok County, Kenya. METHODS: a cross-sectional study utilizing a self administered questionnaire, targeting 237 health workers and 21 health managers was used. Data analysis was done using SPSS version 21 using descriptive statistics. Factor analysis was done on the training perception in relation to motivation. RESULTS: majority of the respondents rated their motivation between 7 and 9 in the current health facility (35.4%), Sub-county (33.8%) and County (32.9%) with the median motivation level of 5. Majority of health workers 194 (81.9%) had received a form of training, of whom 191 (98.5%) indicated that on-job training was relevant to their tasks and that it motivated 192 (99.0%) of them to perform better due to coining skills to motivation. Training significantly predicted general motivation (p-value = 0.013), job satisfaction (p-value = .001), intrinsic job satisfaction (p-value = .001) and organisational commitment (p-value <.001). CONCLUSION: the researchers concluded that there is a relationship between training and motivated health workforce in Narok County and recommended strengthening of current training initiatives by ensuring trainings are more regular and involvement of health workers in discussing their career development prospects.

Abstract: Bioassay-guided fractionation of the mycelial extract of a basidiomycete culture collected in Kenya led to the isolation of two new cyathane diterpenoids named laxitextines A (1) and B (2). The producer strain was characterized by detailed taxonomic studies based on rDNA using the 5.8S gene region, the internal transcribed spacer 2 (ITS2), and part of the large subunit that identified the fungus as Laxitextum incrustatum. The structures of 1 and 2 were elucidated by NMR spectroscopic and mass spectrometric analyses. Both compounds exhibited moderate activities against Gram-positive bacteria Bacillus subtilis (DSM 10), Staphylococcus aureus (DSM 346), and methicillin-resistant Staph. aureus (DSM 1182). The two compounds also showed variable antiproliferative activities against mouse fibroblast (L929) and selected human cell lines (breast cancer MCF-7, epidermoid carcinoma A431, and umbilical vein endothelial HUVEC). The IC50 values with respect to the MCF-7 cell line for compounds 1 and 2 were 2.3 and 2.0 ...

Abstract: This study explores the role of access to credit in improving rice production in Sub-Saharan Africa using the case of rice farmers in the large-scale Mwea irrigation scheme in Kenya. Using household level survey data, we find that the use of fertiliser and paddy yield per hectare are not significantly different among borrowers from the cooperative society, borrowers from rice traders and non-borrowers. However, borrowers from rice traders receive lower incomes and profits compared with non-borrowers largely due to the higher interest charged. Considering that such farmers who borrow from rice traders are generally poorer in financial, physical, and human capital and would have even made lower income and profit without rice trader credit, we suggest policies to facilitate further development of credit markets for both efficiency and equity of rice production in Mwea.

Abstract: The Nile tilapia (Oreochromis niloticus) was introduced into Lake Victoria in the early 1950s and 1960s and has since become the dominant tilapiine in the lake. This study investigated the growth and population parameters of O. niloticus in Lake Victoria on the basis of length–frequency data collected during the period June 2014 and June 2015. The asymptotic length (L∞) had a mean (±SE) value of 46.24 ± 0.04 cm TL, growth curvature (K) of 0.69 ± 0.25 year⁻¹, total mortality (Z) of 2.18 ± 0.80 year⁻¹, a natural mortality (M) of 1.14 ± 0.28 year⁻¹, a fishing mortality (F) of 1.05 ± 0.53 year⁻¹, an exploitation rate (E) of 0.46 ± 0.08, a growth performance index (∅) of 3.14 ± 0.17 and a length at first capture (LC₅₀) of 20.31 ± 0.40 cm TL. Comparing the results of this study with previous studies indicates the parameters K, Z and M have increased, whereas ∅, F, E and LC ₅₀ have decreased. Changes in these parameters could be attributed to the existing high fishing capacity, and changing lake conditions. Thus, management measures should include continued restriction on illegal fishing methods and gears, such as the use of undersized gillnets (<5 in. mesh size) and beach seines. More attention also should be directed to the implementation of measures to control pollution of the lake from its various sources.

Abstract: Background Increasing resistance to anti-tuberculosis drugs has driven the need for developing new drugs. Resources such as the tropical disease research (TDR) target database and AssessDrugTarget can help to prioritize putative drug targets. Hower, these resources do not necessarily map to metabolic pathways and the targets are not involved in dormancy. In this study, we specifically identify drug resistance pathways to allow known drug resistant mutations in one target to be offset by inhibiting another enzyme of the same metabolic pathway. One of the putative targets, Rv1712, was analysed by modelling its three dimensional structure and docking potential inhibitors.

Abstract: Geophagia is defined as deliberate consumption of earths’ materials, e.g. soil, clay and soft stones. The practice is widespread among pregnant women, and there are conflicting views as to whether it is beneficial to health or not. Geophagic materials may be a source of micronutrients though the materials may bind the micronutrients thus reducing or hindering their bioavailability in the body. Geophagia is closely associated with geohelminthic infections among pregnant women and heavy metal poisoning, which constitute significant public health problem in many developing countries such as Kenya. In our research, the geophagic materials consumed by the pregnant women were studied. A total of 38 geophagic materials in the possession by different pregnant women were analysed. The collected samples were subjected to standard digestion procedures and analysed for zinc, lead and iron by atomic absorption spectroscopy. Results indicated that the geophagic materials contained elevated levels of Fe at mean concentration value of 80.10 ppm, Pb at 3.28 ppm and Zn 1.81 ppm for a 1.00 g sample. An average of 20 g of the geophagic materials was being consumed per day. Based on the average consumption, the pregnant women were exposed to 65.52 ppm Pb per day, 36.2 ppm Zn per day and 1602 ppm Fe per day. Lead exceeded the WHO-lead exposure limits of 25 ppm/day for pregnant women. The materials were also subjected to microscopic examination for Ascaris lumbricoides, Trichuris trichiura, Taenia Spp., Necator americanus and Ancylostomaduodenale. In conclusion, the women were exposed to heavy metals—iron, zinc and lead, but there was no observable eggs, larvae or adult species of the geohelminths. The key recommendation was that there is need to integrate public health education on geophagia, lead screening and testing with antenatal support care systems. This will enhance maternal and child health, thus reducing infant and maternal morbidity and mortality rates.

Abstract: Objective To assess, within communities experiencing Ebola virus outbreaks, the risks associated with the disposal of human waste and to generate recommendations for mitigating such risks. Methods A team with expertise in the Hazard Analysis of Critical Control Points framework identified waste products from the care of individuals with Ebola virus disease and constructed, tested and confirmed flow diagrams showing the creation of such products. After listing potential hazards associated with each step in each flow diagram, the team conducted a hazard analysis, determined critical control points and made recommendations to mitigate the transmission risks at each control point. Findings The collection, transportation, cleaning and shared use of blood-soiled fomites and the shared use of latrines contaminated with blood or bloodied faeces appeared to be associated with particularly high levels of risk of Ebola virus transmission. More moderate levels of risk were associated with the collection and transportation of material contaminated with bodily fluids other than blood, shared use of latrines soiled with such fluids, the cleaning and shared use of fomites soiled with such fluids, and the contamination of the environment during the collection and transportation of blood-contaminated waste. Conclusion The risk of the waste-related transmission of Ebola virus could be reduced by the use of full personal protective equipment, appropriate hand hygiene and an appropriate disinfectant after careful cleaning. Use of the Hazard Analysis of Critical Control Points framework could facilitate rapid responses to outbreaks of emerging infectious disease.

Abstract: The most common milk handling containers used by dairy actors along the informal milk value chain in developing countries are plastics jerry cans which are difficult to effectively be cleaned thus contributing immensely to milk contamination and consequently post-harvest losses. The aim of this study was to determine the effectiveness of some common cleaning regimes used by the dairy actors in Kenya against reduction of surface microbial load on jerry cans. Milk handling plastic jerry can containers (n = 16) were obtained from dairy actors and then subjected to four different commonly used cleaning regimes alongside a control experiment of aluminium cans (n = 4). These containers were aseptically swabbed in three replicates before and after the application of a cleaning regime and the swabs (n = 120) analyzed for Total Viable Count (TVC), Total Coliform Count (TCC) and Lactic Acid Bacteria (LAB). The quantitative mean difference of the bacterial load reduction between before and after the application of a cleaning regime was used as the measure of its effectiveness. The study found out that irrespective of the cleaning, the type of container was significant (P < 0.001) in the reduction of microbial contaminants, whereby the aluminium cans had the highest microbial load reduction of 86, 85 and 96 % for TVC, TCC and LAB respectively as compared to 40, 28 and 42 % for TVC, TCC and LAB respectively for plastic jerry cans. The use of a commercial scourer in the cleaning was found to significantly reduce (P < 0.05) only TVC and TCC. The results from this study explains the unsuitability of plastic jerry cans in handling of milk and a risk factor for milk post-harvest losses in Kenya through microbial contamination.

Abstract: The Lake Baringo and Lake Victoria regions of Kenya are associated with high seroprevalence of mosquito-transmitted arboviruses. However, molecular identification of potential mosquito vector species, including morphologically identified ones, remains scarce. To estimate the diversity, abundance, and distribution of mosquito vectors on the mainland shores and adjacent inhabited islands in these regions, we collected and morphologically identified adult and immature mosquitoes and obtained the corresponding sequence variation at cytochrome c oxidase 1 (COI) and internal transcribed spacer region 2 (ITS2) gene regions. A total of 63 species (including five subspecies) were collected from both study areas, 47 of which have previously been implicated as disease vectors. Fourteen species were found only on island sites, which are rarely included in mosquito diversity surveys. We collected more mosquitoes, yet with lower species composition, at Lake Baringo (40,229 mosquitoes, 32 species) than at Lake Victoria (22,393 mosquitoes, 54 species). Phylogenetic analysis of COI gene sequences revealed Culex perexiguus and Cx tenagius that could not be distinguished morphologically. Most Culex species clustered into a heterogeneous clade with closely related sequences, while Culex pipiens clustered into two distinct COI and ITS2 clades. These data suggest limitations in current morphological identification keys. This is the first DNA barcode report of Kenyan mosquitoes. To improve mosquito species identification, morphological identifications should be supported by their molecular data, while diversity surveys should target both adults and immatures. The diversity of native mosquito disease vectors identified in this study impacts disease transmission risks to humans and livestock.

Abstract: The Magadi tilapia, Alcolapia grahami, a small cichlid fish of Lake Magadi, Kenya lives in one of the most challenging aquatic environments on earth, characterized by very high alkalinity, unusual water chemistry, and extreme O2, ROS, and temperature regimes. In contrast to most fishes which live at temperatures substantially lower than the 36–40 °C of mammals and birds, an isolated population (South West Hot Springs, SWHS) of Magadi tilapia thrives in fast-flowing hotsprings with daytime highs of 43 °C and night-time lows of 32 °C. Another population (Fish Springs Lagoon, FSL) lives in a lagoon with fairly stable daily temperatures (33–36 °C). The upper critical temperatures (Ctmax) of both populations are very high; moreover the SWHS tilapia exhibit the highest Ctmax (45.6 °C) ever recorded for a fish. Routine rates of O2 consumption (MO2) measured on site, together with MO2 and swimming performance at 25, 32, and 39 °C in the laboratory, showed that the SWHS tilapia exhibited the greatest metabolic performance ever recorded in a fish. These rates were in the basal range of a small mammal of comparable size, and were all far higher than in the FSL fish. The SWHS tilapia represents a bellwether organism for global warming.

Abstract: The relationship between off-farm work and farm input use in Sub-Saharan Africa has been documented, although results are mixed concerning the direction of effect. Here, we explore the robustness of this linkage by applying a range of econometric models to panel data collected in Kenya, using maize as an example because of its importance as a major food crop among smallholder farmers. We test the relationship between rates of fertilizer use and three types of off-farm earnings (labour on other farms, known as farm kibarua); income from self-employment and informal businesses and earnings from regular employment (salaries, pensions or wages). Consistent with previous research, we find a strong, negative linkage between non-farm work and rates of fertiliser use in maize production, indicating trade-offs in labour allocation and farm investments. However, the relationship between fertiliser use in maize production and earnings from farm kibarua appears to be positive, illustrating the role this type of work can play in easing cash constraints for destitute households. Adding to previous research, model comparisons illustrate the sensitivity of some estimated parameters to modelling assumptions. Further, the application of the general propensity score matching demonstrates that the magnitude of the marginal effects of non-farm income on fertiliser use rates varies as income changes. In the case of non-farm earnings, the response of fertiliser to additional income is negative at lower income levels, but positive at higher levels.

Abstract: The soda lakes of the East African Rift System are unique water bodies whose formation, topography and locational settings have conferred upon them endorheic basin features with arid to semiarid climatic conditions. These features, together with the geological characteristics of their catchments, have favoured the development of saline alkaline properties that make them peculiar and important from a number of perspectives. Most of these lakes have extreme environmental characteristics shown by high ionic contents of their water, high temperature conditions and eutrophic states. This enables them to support growth of few tolerant species of extremophilic Cyanobacteria and other microbes. Some of these lakes such as the Lakes Nakuru and Bogoria are highly productive, yielding some of the highest primary production rates in the world. This high productivity supports hundreds of thousands to, sometimes, millions of Lesser Flamingos in these two lakes. These lakes, however, are highly vulnerable to climate changes and environmental degradation associated with human activities due to their unique environmental conditions. This paper explores some of these unique features, the threats to their existence, the challenges to their conservation and potential strategies to protect them.

Abstract: The attempt to understand the kinetic behavior of nicotine in tobacco will provide a basis for unraveling its energetics in tobacco burning and the formation of free radicals considered harmful to the cigarette smoking community. To the best of our knowledge, the high temperature destruction kinetic characteristics of nicotine have not been investigated before; hence this study is necessary especially at a time addiction science and tobacco research in general is gaining intense attention. The pyrolysis of tobacco under conditions simulating cigarette smoking in the temperature region 200–700 °C has been investigated for the evolution of nicotine and pyridine from two commercial cigarettes coded ES1 and SM1 using gas chromatography hyphenated to a mass selective detector (MSD). Moreover, a kinetic model on the thermal destruction of nicotine within a temperature window of 673 and 973 K is proposed using pseudo-first order reaction kinetics. A reaction time of 2.0 s was employed in line with the average puff time in cigarette smoking. Nonetheless, various reaction times were considered for the formation kinetics of nicotine. GC–MS results showed the amount of nicotine evolved decreased with increase in the puff time. This observation was remarkably consistent with UV–Vis data reported in this investigation. Generally, the temperature dependent rate constants for the destruction of nicotine were found to be $$k = 2.1\; \times \;10^{6} T^{n} \; \times \;e^{{ - \,\frac{108.85}{RT}}}$$ s−1 and $$k = 3.0\; \times \;10^{7} T^{n} \; \times \;e^{{ - \,\frac{136.52}{RT}}}$$ s−1 for ES1 and SM1 cigarettes respectively. In addition, the amount of nicotine evolved by ES1 cigarette was ~10 times more than the amount of nicotine released by SM1 cigarette. The suggested mechanistic model for the formation of pyridine from the thermal degradation of nicotine in tobacco has been found to be agreement with the kinetic model proposed in this investigation. Consequently, the concentration of radical intermediates of tobacco smoke such as pyridinyl radical can be determined indirectly from a set of integrated rate laws. This study has also shown that different cigarettes can yield varying amounts of nicotine and pyridine depending on the type of cigarette primarily because of potential different growing conditions and additives introduced during tobacco processing. The activation energy of nicotine articulated in this work is consistent with that reported in literature.

Abstract: Cassava brown streak disease is endemic to the coastal regions of East Africa, and from around 2004, the disease resurged and became epidemic in the Great Lakes Region, where it continues to spread. In both these areas, cassava brown streak disease (CBSD) leaf symptoms occur at high incidences. However, it is the associated symptom of root rot (necrosis) in the starch-bearing tissues that renders the root unfit for human consumption. Because the extent of root necrosis is not known until the crop is harvested and surveys require destructive sampling, root symptoms are much less frequently assessed than are the above-ground symptoms on the leaves and stems. Surveys were undertaken in selected villages in Tanzania, Kenya, Uganda and Malawi to assess the incidence of CBSD leaf symptoms and the incidence and severity of root symptoms, to estimate the impact of the disease on household food security and on cassava processing. CBSD leaf symptoms were recorded at high incidences (40–90% in individual fields) in all fields visited throughout East Africa, but root necrosis incidence was lower than would be expected from the high incidence of leaf symptoms. Severe root necrosis at high incidence was found only on a few varieties, usually grown to a limited extent. It appears that varieties that are prone to root necrosis are being abandoned in favour of those with a lower propensity to develop root necrosis after infection by the virus.

Abstract: Consensus of opinion in literature regarding tobacco research has shown that cigarette smoke can cause irreparable damage to the genetic material, cell injury, and general respiratory landscape. The alkaloid family of tobacco has been implicated is a series of ailments including addiction, mental illnesses, psychological disorders, and cancer. Accordingly, this contribution describes the mechanistic degradation of major tobacco alkaloids including the widely studied nicotine and two other alkaloids which have received little attention in literature. The principal focus is to understand their energetics, their environmental fate, and the formation of intermediates considered harmful to tobacco consumers. The intermediate components believed to originate from tobacco alkaloids in mainstream cigarette smoke were determined using as gas-chromatography hyphenated to a mass spectrometer fitted with a mass selective detector (MSD) while the energetics of intermediates were conducted using the density functional theory framework (DFT/B3LYP) using the 6-31G basis set. The density functional theory calculations conducted using B3LYP correlation function established that the scission of the phenyl C–C bond in nicotine and β-nicotyrine, and C–N phenyl bond in 3,5-dimethyl-1-phenylpyrazole were respectively 87.40, 118.24 and 121.38 kcal/mol. The major by-products from the thermal degradation of nicotine, β-nicotyrine and 3,5-dimethyl-1-phenylpyrazole during cigarette smoking are predicted theoretically to be pyridine, 3-methylpyridine, toluene, and benzene. This was found to be consistent with experimental data presented in this work. Clearly, the value of the bond dissociation energy was found to be dependent on the π–π interactions which plays a primary role in stabilizing the phenyl C–C in nicotine and β-nicotyrine and the phenyl C–N linkages in 3,5-dimethyl-1-phenylpyrazole. This investigation has elucidated the energetics for the formation of free radicals and intermediates considered detrimental to human health in cigarette smoking. Graphical abstract Some molecular alkaloids of tobacco the plant