Quantitative Trait Loci Mapping in Maize for Resistance to Larger Grain Borer

Storability of maize grain is constrained by the larger grain borer (LGB) (Prostephanus truncatus). Host plant resistance is the most feasible way to manage LGB among smallholder farmers. Breeding for resistance to this pest inmaize is dependent on understanding genetic mechanisms underlying the resistance. The objective of this study was to map quantitative trait loci (QTL) associated with LGB resistance in tropical maize. A mapping populationof 203 F2:3 derived progenies was developed from a cross between susceptible and resistant inbred lines.The F2:3 progenies were crossed to a tester and testcrosses evaluated across six environments, followed by screening for resistance to LGB. Data was collected on husk cover tip length, and grain texture in the field. Biochemical traits were analyzed on the maize grain. Harvested grain was evaluated for resistance and data recorded on grain damage, weight loss, and several insects. Grain hardness was measured as a putative trait of resistance. Univariate analysis of variance for all the traits was done using the general linear model of the statistical analysis system.Genetic mapping was done using Joinmap 4, while QTL analysis was done using PLABQTL. The QTL for resistance were mapped to 6 out of the ten chromosomes. QTL for resistance traits were located in chromosomes 1, 5 and 9.Chromosome 1 had a common QTL linked to protein content, grain hardness, and husk cover tip length. Additive genetic effects were prevalent in all detected QTL. Overall, the studies show that breeding for resistance to LGB is possible

Quantitative Analysis of Total Phenolic Content in Avocado (Persia Americana) Seeds in Eastern Province of Kenya

Phytochemical rich plants have played a significant role in diet based therapies to prevent and cure various ailments. The avocado (Persia Americana Mill,) fruits are much sought after for their high nutritional and sensory value. Avocado (Persia Americana) seeds were analysed for total phenolic content. This phenolic component is responsible for antioxidant activity. The amount of phenols was analysed using Folin-Ciocalteu method. The maximum phenolic content was found in the Fuerte seed extract (18.55 ± 2.8 mg/g) prepared at 50ºC. The phenolic content decreased by 10.3% at an extraction temperature of 50 °C to 70 °C and 32.1% at an extraction temperature of 50 °C to 100 °C for a duration of 30 minutes. Keywords: Avocado seeds, Persia Americana, Total phenolic

Responses of tropical maize landraces to damage by Chilo partellus stem borer

The potential to manage insect pests using host-plant resistance exists, but has not been exploited adequately. The objective of this study was to determine the resistance of 75 tropical maize landraces through artificial infestation with Chilo partellus Swinhoe. The trial was laid in alpha-lattice design and each seedling was infested with five neonates three weeks after planting, over two seasons in 2009 and 2010. The number of exit holes, tunnel length, ear diameter, ear length, plant height, stem diameter, stem lodging and grain yield were measured and a selection index computed. GUAT 1050 was the most resistant with an index of 0.56, while BRAZ 2179 was the most susceptible with an index of 1.66. Ear characteristics were negatively correlated with damage parameters. The principal component biplot suggested that exit holes, cumulative tunnel length, leaf damage, cob diameter, stem lodging, selection index, ear and plant height contributed 71.2% of the variation in resistance. The mean number of exit holes and tunnel length for resistant landraces and resistant hybrid checks were similar; at 5.5 and 2.48 cm, respectively. The identified resistant landraces (GUAT 1050, GUAT 280, GUAT 1093, GUAT 1082, GUAT 1014, CHIS 114, and GUAN 34) could be used to develop C. partellus stem borer-resistant maize genotypes.Key words: Chilo partellus, ear length, exit holes, stem borer resistance, tunnel length

Molecular characterization of rotavirus group A strains circulating prior to vaccine introduction in rural coastal Kenya, 2002-2013

Background Kenya introduced the monovalent Rotarix® rotavirus group A (RVA) vaccine nationally in mid-2014. Long-term surveillance data is important prior to wide-scale vaccine use to assess the impact on disease and to investigate the occurrence of heterotypic strains arising through immune selection. This report presents baseline data on RVA genotype circulation patterns and intra-genotype genetic diversity over a 7-year period in the pre-vaccine era in Kilifi, Kenya, from 2002 to 2004 and from 2010 to 2013. Methods A total of 745 RVA strains identified in children admitted with acute gastroenteritis to a referral hospital in Coastal Kenya, were sequenced using the di-deoxy sequencing method in the VP4 and VP7 genomic segments (encoding P and G proteins, respectively). Sequencing successfully generated 569 (76%) and 572 (77%) consensus sequences for the VP4 and VP7 genes respectively. G and P genotypes were determined by use of BLAST and the online RotaC v2 RVA classification tool. Results The most common GP combination was G1P[8] (51%), similar to the Rotarix® strain, followed by G9P[8] (15%) , G8P[4] (14%) and G2P[4] (5%). Unusual GP combinations—G1P[4], G2P[8], G3P[4,6], G8P[8,14], and G12P[4,6,8]—were observed at frequencies of <5%. Phylogenetic analysis showed that the infections were caused by both locally persistent strains as evidenced by divergence of local strains occurring over multiple seasons from the global ones, and newly introduced strains, which were closely related to global strains. The circulating RVA diversity showed temporal fluctuations both season by season and over the longer-term. None of the unusual strains increased in frequency over the observation period. Conclusions The circulating RVA diversity showed temporal fluctuations with several unusual strains recorded, which rarely caused major outbreaks. These data will be useful in interpreting genotype patterns observed in the region during the vaccine er

Genetic diversity analysis in tropical maize germplasm for stem borer and storage pest resistance using molecular markers and phenotypic traits

One hundred maize inbred lines and eighty four hybrids were characterized for resistance to maize stem borer and post-harvest insect pests. This was achieved using genetic distance and population structure based on simple sequence repeat (SSR) markers and biophysical traits. The test materials were evaluated for stem borer, maize weevil and larger grain borer (LGB) resistance. Leaf samples were harvested from 10 healthy plants per genotype and bulked. Genomic DNA was extracted using a modified version of mini-prep Cetyl Trimethyl Ammonium Bromide (CTAB) method. The samples were genotyped with 55 SSRs makers. Univariate analysis of variance was done using the general linear model procedure of SAS statistical package. Rodgers genetic distance was calculated for all data sets as a measure of genetic distance using NTSYS-pc for Windows. The distance matrices were used to generate phenograms using the unweighted pair group method based on arithmetic average (UPGMA) method in MEGA5. The genotypes were assigned into different populations using population structure software. The data was further subjected to discriminant and principal component analysis to group the gnotyoes. Analysis of molecular variance within and among the different populations was done using arlequin. There were significant differences (P ≤ 0.001) for all the biophysical traits evaluated. The SSR marker data estimated successfully the close relationship among different hybrids and inbred lines within clusters. Comparisons of the different multivariate analyses revealed high concordance among the different approaches of analyses. The results of this study can be directly used by breeding programs to develop resistant genotypes

Prevalence and determinants of human papillomavirus infection and cervical lesions in HIV-positive women in Kenya

Background: We assessed the association of human papillomavirus (HPV) infection and cervical intraepithelial neoplasia (CIN) with various characteristics, CD4 count and use of combination antiretroviral therapy (cART) among HIV-positive women. Methods: Cross-sectional study of 498 HIV-positive women who underwent HPV PCR-based testing, cytology, and systematic cervical biopsy. Results: In all, 68.7% of women were HPV-positive, 52.6% had high-risk (hr) HPV, and 40.2% multiple type infections. High-risk human papillomavirus-positivity did not vary significantly by age but it was negatively associated with education level. The most frequent types in 113 CIN2/3 were HPV16 (26.5%), HPV35 (19.5%), and HPV58 (12.4%). CD4 count was negatively associated with prevalence of hrHPV (Po0.001) and CIN2/3 among non-users of cART (P¼0.013). Combination antiretroviral therapies users (X2 year) had lower hrHPV prevalence (prevalence ratio (PR) vs non-users¼0.77, 95% confidence interval (CI): 0.61–0.96) and multiple infections (PR¼0.68, 95% CI: 0.53–0.88), but not fewer CIN2/3. The positive predictive value of hrHPV-positivity for CIN2/3 increased from 28.9% at age o35 years to 53.3% in X45 years. Conclusion: The burden of hrHPV and CIN2/3 was high and it was related to immunosuppression level. Combination antiretroviral therapies (X2 year) use had a favourable effect on hrHPV prevalence but cART in our population may have been started too late to prevent CIN2/3

Effect of an opt-out point-of-care HIV-1 nucleic acid testing intervention to detect acute and prevalent HIV infection in symptomatic adult outpatients and reduce HIV transmission in Kenya: a randomized controlled trial

Background: In sub-Saharan Africa, adult outpatients with symptoms of acute infectious illness are not routinely tested for prevalent or acute HIV infection (AHI) when seeking healthcare. Methods: Adult symptomatic outpatients aged 18–39 years were evaluated by a consensus AHI risk score. Patients with a risk score ≥ 2 and no previous HIV diagnosis were enrolled in a stepped-wedge trial of opt-out delivery of point-of-care (POC) HIV-1 nucleic acid testing (NAAT), compared with standard provider-initiated HIV testing using rapid tests in the observation period. The primary outcome was the number of new diagnoses in each study period. Generalized estimating equations with a log-binomial link and robust variance estimates were used to account for clustering by health facility. The trial is registered with ClinicalTrials.gov NCT03508908. Results: Between 2017 and 2020, 13 (0.9%) out of 1374 participants in the observation period and 37 (2.5%) out of 1500 participants in the intervention period were diagnosed with HIV infection. Of the 37 newly diagnosed cases in the intervention period, two (5.4%) had AHI. Participants in the opt-out intervention had a two-fold greater odds of being diagnosed with HIV (odds ratio = 2.2, 95% confidence interval: 1.39–3.51) after adjustment for factors imbalanced across study periods. Conclusions: Among symptomatic adults aged 18–39 years targeted by our POC NAAT intervention, we identified one chronic HIV infection for every 40 patients and one AHI patient for every 750 patients tested. Although AHI yield was low in this population, routinely offered opt-out testing could diagnose twice as many patients as an approach relying on provider discretion

Cervical HIV-1 RNA shedding after cryotherapy among HIV-positive women with cervical intraepithelial neoplasia stage 2 or 3

Objective: To determine the effect of cryotherapy on HIV-1 cervical shedding. Design: Prospective cohort study. Methods: Five hundred HIV-positive women enrolled at an HIV treatment clinic in Nairobi, Kenya were screened for cervical cancer. Women diagnosed with cervical intraepithelial neoplasia stage 2 or 3 (CIN 2/3) by histology were offered cryotherapy treatment. The first 50 women had cervical swabs taken at baseline and at 2 and 4 weeks following treatment. Swabs were analyzed for HIV-1 RNA and compared using General Estimating Equation (GEE) with binomial or Gaussian links. Results: Of the 50 women enrolled, 40 were receiving antiretroviral therapy (ART) and 10 were not receiving ART at the time of cryotherapy and during study follow-up. Among all women, the odds of detectable cervical HIV-1 RNA did not increase at 2 weeks [odds ratio (OR) 1.18; 95% confidence interval (CI) 0.65-2.13] or 4 weeks (OR 1.29; 95% CI 0.71-2.33) following cryotherapy. Among 10 women not receiving ART, the OR of detectable shedding at 2 weeks was higher, but not statistically significant (OR 4.02; 95% CI 0.53-30.79; P = 0.2), and at 4 weeks remained unchanged (OR 1.00; 95% CI 0.27-3.74). Conclusion: There was no increase in detectable cervical HIV-1 RNA among HIV-positive women after cryotherapy. The risk of HIV-1 transmission after cryotherapy may not be significant, particularly among women already on ART at the time of cervical treatment. However, further investigation is needed among women not receiving ART

Comparing Papanicolau smear, visual inspection with acetic acid and human papillomavirus cervical cancer screening methods among HIV-positive women by immune status and antiretroviral therapy

Background: A rigorous comparison of cervical cancer screening methods utilizing data on immune status, antiretroviral therapy (ART) and colposcopy-directed biopsy has not been performed among HIV-positive women. Methods: Between June and November 2009, 500 HIV-positive women were enrolled at an HIV treatment clinic in Nairobi, Kenya, and underwent Papanicolau (Pap) smear, visual inspection with acetic acid (VIA), human papillomavirus (HPV) and colposcopydirected biopsy (gold standard). Positive Pap smear (ASCUS, LSIL, HSIL), VIA, HPV and their combinations were compared with CIN2/3+. Sensitivity, specificity and AUC (sensitivity and 1-specificity) were compared using pairwise tests and multivariate logistic regression models that included age, CD4+ cell count and ART duration. Results:Of 500 enrolled, 498 samples were collected. On histology, there were 172 (35%) normal, 186 (37%) CIN1, 66 (13%) CIN2, 47 (9%) CIN3 and 27 (5%) indeterminate. Pap (ASCUS+) was the most sensitive screening method (92.7%), combination of both Pap (HSIL+) and VIA positive was the most specific (99.1%) and Pap (HSIL+) had the highest AUC (0.85). In multivariate analyses, CD4+ cell count of 350 cells/ml or less was associated with decreased HPV specificity (P=0.002); ART duration of less than 2 years was associated with decreased HPV (P=0.01) and VIA (P=0.03) specificity; and age less than 40 years was associated with increased VIA sensitivity (P Conclusion: Pap smear is a robust test among HIV-positive women regardless of immune status or ART duration. Results should be cautiously interpreted when using HPV among those younger, immunosuppressed or on ART less than 2 years, and when using VIA among those aged 40 years or more

Closing the yield gap of soybean (Glycine max (L.) Merril) in southern Africa: a case of Malawi, Zambia, and Mozambique.

Open Access JournalIntroduction: Smallholder farmers in Sub-Saharan Africa (SSA) are increasingly producing soybean for food, feed, cash, and soil fertility improvement. Yet, the difference between the smallholder farmers’ yield and either the attainable in research fields or the potential from crop models is wide. Reasons for the yield gap include low to nonapplication of appropriate fertilizers and inoculants, late planting, low plant populations, recycling seeds, etc. Methods: Here, we reviewed the literature on the yield gap and the technologies for narrowing it and modelled yields through the right sowing dates and suitable high-yielding varieties in APSIM. Results and Discussion: Results highlighted that between 2010 and 2020 in SSA, soybean production increased; however, it was through an expansion in the cropped area rather than a yield increase per hectare. Also, the actual smallholder farmers’ yield was 3.8, 2.2, and 2.3 times lower than the attainable yield in Malawi, Zambia, and Mozambique, respectively. Through inoculants, soybean yield increased by 23.8%. Coupling this with either 40 kg ha−1 of P or 60 kg ha−1 of K boosted the yields by 89.1% and 26.0%, respectively. Overall, application of 21–30 kg ha-1 of P to soybean in SSA could increase yields by about 48.2%. Furthermore, sowing at the right time increased soybean yield by 300%. Although these technologies enhance soybean yields, they are not fully embraced by smallholder farmers. Hence, refining and bundling them in a digital advisory tool will enhance the availability of the correct information to smallholder farmers at the right time and improve soybean yields per unit area