Seismicity from february 2006 to september 2007 at the Rwenzori Mountains, East African Rift: earthquake distribution, magnitudes and source mechanisms

We have analysed the microseismic activity within the Rwenzori Mountains area in the western branch of the East African Rift. Seismogram recordings from a temporary array of up to 27 stations reveal approximately 800 events per month with local magnitudes ranging from –0.5 to 5.1. The earthquake distribution is highly heterogeneous. The majority of located events lie within faults zones to the east and west of the Rwenzoris with the highest seismic activity observed in the northeastern area, where the mountains are in contact with the rift shoulders. The hypocentral depth distribution exhibits a pronounced peak of seismic energy release at 15 km depth. The maximum extent of seismicity ranges from 20 to 32 km and correlates well with Moho depths that were derived from teleseismic receiver functions. We observe two general features: (i) beneath the rift shoulders, seismicity extends from the surface down to ca. 30 km depth; (ii) beneath the rift valley, seismicity is confined to depths greater than 10 km. From the observations there is no indication for a crustal root beneath the Rwenzori Mountains. The magnitude frequency distribution reveals a b-value of 1.1, which is consistent with the hypothesis that part of the seismicity is caused by magmatic processes within the crust. Fault plane solutions of 304 events were derived from P-polarities and SV/P amplitude ratios. More than 70 % of the source mechanisms exhibit pure or predominantly normal faulting. T-axis trends are highly uniform and oriented WNW–ESE, which is perpendicular to the rift axis and in good agreement with kinematic rift models. At the northernmost part of the region we observe a rotation of the T-axis trends to NEN–SWS, which may be indicative of a local perturbation of the regional stress field

Seismicity at the Rwenzori Mountains, East African Rift: earthquake distribution, magnitudes and source mechanisms

We have analysed the microseismic activity within the Rwenzori Mountains area in the western branch of the East African Rift. Seismogram recordings from a temporary array of up to 27 stations reveal approximately 800 events per month with local magnitudes ranging from –0.5 to 5.1. The earthquake distribution is highly heterogeneous. The majority of located events lie within faults zones to the East and West of the Rwenzoris with the highest seismic activity observed in the northeastern area, where the mountains are in contact with the rift shoulders. The hypocentral depth distribution exhibits a pronounced peak of seismic energy release at 15 km depth. The maximum extent of seismicity ranges from 20 to 32 km and correlates well with Moho depths that were derived from teleseismic receiver functions. We observe two general features: (i) beneath the rift shoulders seismicity extends from the surface down to ca. 30 km depth; (ii) beneath the rift valley seismicity is confined to depths greater than 10 km. From the observations there is no indication for a crustal root beneath the Rwenzori Mountains. The magnitude frequency distribution reveals a b-value of 1.1, which is consistent with the hypothesis that part of the seismicity is caused by magmatic processes within the crust. Fault plane solutions of 304 events were derived from P-polarities and SV/P amplitude ratios. More than 70 % of the source mechanisms exhibit pure or predominantly normal faulting. T-axis trends are highly uniform and oriented WNW-ESE, which is perpendicular to the rift axis and in good agreement with kinematic rift models. At the northernmost part of the region we observe a rotation of the T-axis trends to NEN-SWS, which may be indicative of a local perturbation of the regional stress field

Increasing efficiency of the breeding pipeline for East African highland bananas

Banana breeding is a technically challenging endeavor due to the low reproductive fertility, low seed germination, long selection cycle period and large space requirement for field evaluation, among others. Innovations in the current breeding program are required to increase the rate of genetic gain delivery to farmers. This study considers five approaches to tackle this challenge; 1) assessment of the available minimum descriptor list for suitability to characterize the East African highland banana (EAHB) germplasm, 2) analysis of crossbreeding data of EAHB for the first 21 years (from 1995 to 2015) at the International Institute of Tropical Agriculture as a basis for designing future interventions, 3) path analysis to determine a breeding ideotype for EAHB, 4) estimation of heterobeltiosis (hybrid vigour) for the NARITA hybrids (mostly secondary triploids ensuing from the 4x × 2x), and 5) phenotyping a diploid banana population (‘Calcutta 4’ × ‘Zebrina GF’ ) for resistance to Radopholus similis. Ten out of 31 descriptors studied were stable but had similar scores in EAHB cultivars and therefore are not suitable to distinguish between them. The month of pollination did not result in significantly different (P = 0.501) pollination success, implying that pollination of EAHB can be conducted throughout the year. However, the seed set, and rate of germination were still low. Thus, further research about seed production and germination is required. Twenty-seven NARITAs were selected for further evaluation in the East African region. Path analysis revealed that fruit length, circumference and number, number of hands and plant cycle number had a direct positive effect on the bunch weight (a proxy for edible yield). Significant progressive heterobeltiosis for bunch weight was found in all the NARITAs. Half of the NARITAs had negative heterobeltiosis for stature. The diploid population was found to segregate for resistance to R. similis. Results from Dunnett’s test grouped the population in three main phenotypic classes, with 75 susceptible, 17 intermediates and 19 resistant genotypes. Chi-square goodness of fit test revealed that this resembles a phenotypic ratio of 9:3:4 suggesting recessive epistasis

Traits that define yield and genetic gain in East African highland banana breeding

East African highland bananas (Musa spp. AAA group) are an important staple in the Great Lakes region of East Africa. Their production has declined due to pests and diseases. Breeding for host plant resistance is a sustainable option for addressing this challenge. Understanding the relationships between growth parameters and bunch weight (i.e., yield) is crucial to guide breeding efforts for this crop. We investigated cause-effect relationships, through path analysis, in bunch weight of East African highland banana derived hybrids, their parents and grandparents. These family structures were planted in a 7 × 8 rectangular lattice design, replicated twice. Genetic gains for bunch weight (kg plant−1) and yield potential (t ha−1 year−1) were estimated. Significant increases of bunch weight and yield potential were noted from the landrace triploid germplasm, their derived primary tetraploid hybrids and secondary triploid bred-germplasm. Path analysis revealed that fruit length, circumference and number, number of hands and plant cycle number had a direct positive effect on the bunch weight. Days to fruit filling, days to maturity and index of non-spotted leaves had indirect effects on bunch weight. The average genetic gains for bunch weight and yield potential were 1.4% and 1.3% per year, respectively. This is the first report about genetic gains in banana breeding. Our findings may be useful for assessing progress and directing future breeding efforts in banana breeding

WCN24-931 AKI Phenotypes in Ugandan children hospitalized with Hypoxemia and Malaria

Introduction: Acute kidney injury (AKI) is a frequent life-threatening complication in hospitalized children. Emerging data suggest AKI is a heterogeneous condition that varies based on the underlying cause and is composed of distinct phenotypes. The objective of this study was to define AKI phenotypes using proposed classification systems in Ugandan children hospitalized with hypoxemia and to evaluate differences in phenotypes by malaria infection. Methods: Between 2019 and 2021, 2402 Ugandan children \u3c5 years of age hospitalized with hypoxemia were enrolled in a cluster randomized trial of solar powered oxygen delivery across 20 districts in Uganda. At enrollment, urine NGAL was measured using a point-of-care lateral flow test with a positive test defined as a level ≥150ng/mL. Malaria was assessed using a threeband rapid diagnostic test. In an extended sub-study, 491 children had creatinine measured to define AKI. AKI was defined using a single creatinine measure at enrolment and phenotypically characterized using two acute dialysis quality initiative (ADQI) proposed AKI phenotypes. The AKI biomarker definition incorporated urine NGAL into the KDIGO definition[group 1, no AKI; group 2, subclinical AKI (biomarker positive); group 3, AKI; group 4, biomarker positive AKI]. The ADQI sepsis AKI phenotype groups stage 1 AKI as sepsis phenotype (SP)-1 irrespective of biomarker status and differentiates severe AKI (stage 2/3) based on biomarker positivity where severe AKI that is biomarker negative is (SP2) and severe biomarker positive AKI is SP3. Results: Overall, 491 children were included in the extended study with AKI defined and uNGAL measured. The median age was 1.3 years (interquartile range, 0.7 to 2.3) and 53.8% of children were male. There were 4 deaths (0.8%) and 24 children required transfer to a higher-level health facility (4.9%). Among children included, 91.2% met a clinical definition of pneumonia and 49.5% were positive for malaria. The frequency of creatinine defined AKI was 32.0% (157/491) and 36.5% (179/491) were biomarker positive. AKI was associated with a 3.24-fold increase in mortality (95% CI 0.34 to 31.4) but underpowered to show a difference. In children without malaria, 17.7% were biomarker positive and AKI negative (subclinical AKI, 44/248) while 37.5% of children had AKI (93/284) of whom 39.8% (37/93) were biomarker positive. In children with malaria, 14.0% had subclinical AKI, 34/243), 59.3% had AKI (144/243) with 44.4% of AKI cases biomarker positive (64/144). Children with malaria had a higher frequency of AKI compared to children without malaria (59.6% vs. 37.6%, p\u3c0.001) but comparable frequency of a positive biomarker test (41.3% vs. 36.2%, p=0.10). Using the sepsis phenotype criteria, 16.3% of children had SP1, 17.9% were SP2 and 14.1% were SP3. When evaluating the sepsis phenotype by malaria status, children with malaria were more likely to have SP2 (23.1% vs. 12.9%) and SP3 (18.1% vs.10.1%) compared to children without malaria (p\u3c0.001). Conclusions: In this population of children hospitalized with hypoxemia across 20 health centers in Uganda, KDIGO-defined AKI was more common in children with malaria. While there was no difference in the AKI-biomarker classification based on malaria status, children with malaria were more likely to have severe phenotypes of AKI

WCN24-2067 Regional differences in acute kidney injury in Ugandan children hospitalized for Hypoxemia

Introduction: Acute kidney injury (AKI) is associated with increased mortality in hospitalized patients and incidence is highest in resource limited settings. The objective of this study was to assess sub-National regional differences in the incidence of AKI in children \u3c5 years of age hospitalized with an acute febrile illness and hypoxemia. Methods: This was a secondary analysis of a stepped wedge cluster randomized controlled trial, which enrolled children \u3c5 years of age hospitalized with hypoxemia between 2019 and 2021. At least one measure of kidney function was available in 1452 children. A single creatinine was measured at enrolment in a sub-set of 495 children with serum stored and AKI defined using KDIGO criteria where baseline creatinine was estimated using the age-based Pottel equation assuming a normal glomerular filtration rate of 120mL/min per 1.73m2. Markers were divided into structural (uNGAL positive, proteinuria, hematuria) or functional (AKI, saliva urea nitrogen (SUN)) measures of kidney injury. Results: 1452 children were included in this AKI sub-study (Figure 1). The mean age of participants was 1.49 years (standard deviation (SD), 1.21) and 55.7% were male (809/1452). Overall 2.6% of children died (38/1452). The majority of participants enrolled were from the West (31.3%) followed by the East (25.3%), North (24.1%), and Central (19.4%) regions. In general, 48.5% of children had AKI (240/495), the prevalence was highest in Eastern Uganda with 62.4% of children having AKI compared to 25.0% of children in Western Uganda, 44% in Central region and 53% in Northern region (p\u3c0.001). Over a third of children had urine NGAL levels ≥150ng/mL, a marker of structural damage, irrespective of site and rates comparable across sites (p=0.095). Other measures of functional and structural kidney injury varied across sites, proteinuria ranged from 6.3% to 14.0% with rates lower in Central and Eastern Uganda compared to Northern and Western Uganda. Hematuria was over two times more common in Eastern and Northern Uganda compared to Central and Western Uganda. Of all the children 49.0 % were positive for malaria based on rapid diagnostic test (RDT) either as positive pLDH or both pLDH and HRP-2. The presence of a single band positive RDT for HRP-2 alone was associated with increased risk of AKI, severe AKI, elevated BUN, a positive SUN test and urinalysis positive for hematuria or urobilinogen (unadjusted p\u3c0.05). Children with a 3-band positive RDT were more likely to have proteinuria, hematuria, bilirubinuria and urobilinogen by dipstick (unadjusted p\u3c0.05). Regional differences in AKI persisted after adjusting for malaria, age, and sex. Conclusions: As we move towards the ISN 0by25 initiative which aims to eliminate preventable deaths from AKI worldwide by 2025. This study provides key in-country data from a resource limited setting, demonstrating marked regional differences in the incidence of AKI in children hospitalized with hypoxaemia and malaria remains an important predictor of AKI. The substantial within-country heterogeneity of AKI highlights the need for further studies to evaluate regional contributors to local patterns of AKI

Heterobeltiosis in banana and genetic gains through crossbreeding

Heterosis, or hybrid vigour, is the superiority of the hybrid for a certain trait over the mean of its two parents. Heterobeltiosis is a form of heterosis where the hybrid is superior to its best parent. Banana breeding is a tedious, time-consuming process, taking up to two decades to develop a hybrid. Understanding heterosis in banana breeding will contribute to selecting right breeding materials for further crossing, thus increasing banana breeding efficiency. Here we document heterobeltiosis by using the recently bred NARITA ‘Matooke’ hybrids and their ancestors. NARITA hybrids, their parents (4x and 2x), grandparents (3x and 2x), and local 3x ‘Matooke’ cultivar checks were planted in a rectangular lattice design with two replications. Yield and other agronomic data were collected at flowering and harvest. The NARITAs were compared with their 3x ‘Matooke’ grandmothers. Heterobeltiosis on bunch weight was calculated with the data of 3 cycles. All the NARITAs showed heterobeltiosis for bunch weight. NARITA 17 had the highest grandparent heterobeltiosis (ca. 250%). Genetic gains due to crossbreeding were determined for fruit yield considering three generations: matooke cultigen (C0), primary tetraploid hybrids (C1) and secondary tetraploid hybrids (C2). The average genetic gain (from C0 to C2) rates for bunch weight (kg) and yield potential (t ha−1 year−1) were 1.4% and 1.3% per year, respectively