Quality of field collected and laboratory reared Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) for screening maize genotypes

The quality of laboratory reared stem borer species for screening of maize varieties is usually questioned by end user cereal breeders. A quality check study was performed in a screen house at KARI-Katumani to evaluate the quality of eight-year old laboratory reared stem borer, Chilo partellus (Swinhoe). The evaluation was aimed at finding out the performance of the laboratory borers subjected to six-month interval of gene infusion in comparison with wild F1 generation of the same species collected from the field. One hundred (100) maize seedlings were grown on plastic pots of 5 by 5 cm and of 12 cm-height. The maize seedlings were infested with five first instar larvae on eight plants replicated four times for each borer ecotype. The wild ecotypes were collected from two different localities for comparison with eight-year old laboratory reared borers. Foliar damage, tunnel length on the maize stems and the recovered number of C. partellus larvae from the maize plants were used as the parameters for quality measure of the borer ecotypes. The laboratory-reared stem borer species had been subjected to frequent six-month gene-infusion interval from the wild. The results indicated feedvoracity drop of 3.8 and 21.5% for stem and foliar damage on the laboratory borer ecotype. The study established the need for continuous gene infusion to maintain high quality maize stem borer species as test organisms.Keywords: Chilo partellus, quality insects, insect rearing, maize genotypes.African Journal of Biotechnology Vol. 12(34), pp. 5370-537

Amides are excellent mimics of phosphate internucleoside linkages and are well tolerated in short interfering RNAs

RNA interference (RNAi) has become an important tool in functional genomics and has an intriguing therapeutic potential. However, the current design of short interfering RNAs (siRNAs) is not optimal for in vivo applications. Non-ionic phosphate backbone modifications may have the potential to improve the properties of siRNAs, but are little explored in RNAi technologies. Using X-ray crystallography and RNAi activity assays, the present study demonstrates that 3\u27-CH2-CO-NH-5\u27 amides are excellent replacements for phosphodiester internucleoside linkages in RNA. The crystal structure shows that amide-modified RNA forms a typical A-form duplex. The amide carbonyl group points into the major groove and assumes an orientation that is similar to the P-OP2 bond in the phosphate linkage. Amide linkages are well hydrated by tandem waters linking the carbonyl group and adjacent phosphate oxygens. Amides are tolerated at internal positions of both the guide and passenger strand of siRNAs and may increase the silencing activity when placed near the 5\u27-end of the passenger strand. As a result, an siRNA containing eight amide linkages is more active than the unmodified control. The results suggest that RNAi may tolerate even more extensive amide modification, which may be useful for optimization of siRNAs for in vivo applications

Linking diet switching to reproductive performance across populations of two critically endangered mammalian herbivores

Optimal foraging theory predicts that animals maximise energy intake by consuming the most valuable foods available. When resources are limited, they may include lower-quality fallback foods in their diets. As seasonal herbivore diet switching is understudied, we evaluate its extent and effects across three Kenyan reserves each for Critically Endangered eastern black rhino (Diceros bicornis michaeli) and Grevy’s zebra (Equus grevyi), and its associations with habitat quality, microbiome variation, and reproductive performance. Black rhino diet breadth increases with vegetation productivity (NDVI), whereas zebra diet breadth peaks at intermediate NDVI. Black rhino diets associated with higher vegetation productivity have less acacia (Fabaceae: Vachellia and Senegalia spp.) and more grass suggesting that acacia are fallback foods, upending conventional assumptions. Larger dietary shifts are associated with longer calving intervals. Grevy’s zebra diets in high rainfall areas are consistently grass-dominated, whereas in arid areas they primarily consume legumes during low vegetation productivity periods. Whilst microbiome composition between individuals is affected by the environment, and diet composition in black rhino, seasonal dietary shifts do not drive commensurate microbiome shifts. Documenting diet shifts across ecological gradients can increase the effectiveness of conservation by informing habitat suitability models and improving understanding of responses to resource limitation

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Assessment of Body Mass Index (BMI) among members of staff of Kenya Medical Training College Nakuru

Background: The harmful effects of overweight and underweight have widely been underestimated worldwide. Body Mass Index (BMI) is a useful indicator to measure if one is underweight, overweight or obese. Setting: The research was conducted at KMTC Nakuru. All members of staff in the college were included in the study. The departments included in the study were Clinical Medicine, Nursing, Pharmacy, Laboratory Science, Environmental Science and physiotherapy. A total of eighty-nine (89) members of staff were studied: Fifteen (15) teaching staff and seventy-four (74) non-teaching staff. Objectives: To determine the BMI of staff members at KMTC Nakuru. Design: The study adopted a descriptive cross-sectional design. Justification: In Kenya and Africa in general, there is current updated data on the prevalence of overweight and obesity. This is particularly so since priority has always been on under-nutrition (Mendez et al., 2005). There has been immense focus primarily on under-nutrition and food insecurity in most African countries since these are more prevalent. As a result, trends in overweight and obesity have often been overlooked in most countries. Data analysis: Scientific calculator was used to generating graphs and tables for data analysis.  Findings: Teaching staff: From the results, 13% of the teaching staff had normal BMI, 60% were overweight and 27% had class I obesity. Non-teaching staff: From the results, 3% were underweight, 39% had normal BMI, 31% were overweight, 19% had class I obesity, 5% had class II obesity and 3% had class III obesity. Conclusion: 60% of the teaching staff was overweight and 27% of the teaching staff was obese while 31% of the non-teaching staff was overweight and 27% were obese

Economic advantage of sorghum harvest at soft dough grain stage to prevent bird damage

Sorghum grain yield is highly reduced by birds in most areas in Africa where these avian pests are abundant. After much consideration on the physiological maturity of the sorghum grain, we designed an approach of early harvest of sorghum grain. The late grain soft dough was identified as the suitable stage to harvest white sorghum as it turns cream white. As the results showed it was possible to salvage over 90% of the grain yield even when high bird infestations were observed in the production plots. A test on seed germination rate showed over 80% grain viability after sun-drying the grain in the open in three different study sites. These results give hope and provide relief on sorghum production where birds are a menace

Therapeutic potential of chemically modified siRNA: Recent trends

Small interfering RNAs (siRNAs) are one of the valuable tools to investigate the functions of genes and are also used for gene silencing. It has a wide scope in drug discovery through in vivo target validation. siRNA therapeutics are not optimal drug-like molecules due to poor bioavailability and immunogenic and off-target effects. To overcome the challenges associated with siRNA therapeutics, identification of appropriate chemical modifications that improves the stability, specificity and potency of siRNA is essential. This review focuses on the various chemical modifications and their implications in siRNA therapy

Positive Yield Impact of Predacious Mites in Tea Production Areas of Kenya

Tea agro ecosystems are least disturbed in comparison to other crop systems due to the plant canopy type. A survey on predacious mites’ abundance and impact on leaf yield in different tea production areas was carried out in 2014-2015 in Kenya. Major pest species were the red spider mite Oligonychus coffeae and the yellow thrip, Scirtothrips dorsalis. The red crevice mite, Brevipalpus phoenicis was found in few areas and in low numbers. Predacious mites of Phytoseiidae Family were highest at 5.8 and 6.8 mites per sample during dry and wet seasons, respectively. Phytoseiid abundance during the dry and wet seasons did not differ much within most sample sites. Presence of phytoseiid mites in combination with NPK-fertilizer-high altitude led to the strongest correlation to leaf yield than any other combination variable. High phytoseiid density- high altitude was third with positive impact to yield increase after high altitude combined with NPK-fertilizer. The findings here show contributory positive impact of phytoseiids in tea leaf yield in an agro eco-system

Cassava Variety Tolerance to Spider Mite Attack in Relation to Leaf Cyanide Level

Cassava, Manihot esculenta Crantz is grown in the tropics as an important staple root crop. The major herbivore pest is cassava green mite (CGM) of the Mononychellus species.  The pest mite Mononychellus progresivus Doreste collected from the coastal Kenya lowlands was used to evaluate spider mite tolerance of nine varieties grown in three regions of the country; eastern lowlands, western midlands and the humid coastal lowlands. Mite population build-up of 10 individual motile stages of M. progresivus reached peak densities on 39th day of the most susceptible varieties and by the 54th day attacked leaves had wilted in 20.0 ± 2 °C and 63 ± 4%, climatic conditions. For the most tolerant varieties it took 47 days to reach peak densities and for one variety (MM97/3567) the mite population did not cause highest damage score even by the 55th day. Equating visual damage score with actual leaf biomass loss (%) enabled indication of the level of photosynthetic leaf area loss due to pest mite attack. Higher leaf cyanide (HCN) content led to higher biomass loss (%) up to HCN 20mg/Kg. Spider mite density increase was similarly positively correlated to the subsequent biomass loss on cassava varieties. This information is beneficial to cassava breeders when developing varieties tolerant to CGM attack and safe for human consumption. Key words: Mononychellus progresivus; damage score; cyanide content; biomass; human consumptio