Bee Diversity and some Aspects of their Ecological Interactions with Plants in a Successional Tropical Community

This study aimed at establishing bee diversity and some aspects of their interactions with plants along a forest regeneration gradient in Kakamega Forest. To determine the bee diversity, bee samples were collected with the help of sweep nets along belt transects for a period of two years, that is, May 2002 to April 2004. In addition, more data on bee species was collected from the existing past records and bee collections from National Museums of Kenya. In total, 243 species of bees represented in four families, of which 234 were sampled in Buyangu Nature Reserve were recorded during the study. These families included Apidae, Halictidae, Megachilidae and Colletidae. In addition, 40 families of representing 189 species of plants were found to support the bee community. The most important plant families included Acanthaceae, Asteraceae and Papilionaceae. A high degree of resource sharing based on niche overlap results was observed between the highly eusocial and the dominant solitary bee species, although the eusocial bees showed the largest niche breadth. Similarly, generalization was more pronounced among the eusocial bees as compared to solitary bees. The results from this study agreed with the expected trend of increased diversity in secondary forests as compared to mature forests. In contrast, generalization was found to increase with forest maturity. In conclusion, the study clearly indicates that bees require a diversity of microhabitats. Secondary forests and surrounding farming areas offer the best refugia sites for bees. On the other hand, the bees cannot survive without the forest for it offers nesting sites and abundant floral resources especially during the dry season when there are no flowers in the open areas. Based on the current results, Kakamega Forest stands out as one of the best bee hot-spots in East Africa. The study advocates further research in pollination biology of wild plants especially on rare plants given that a high level of generalization was documented among the eusocial and solitary bees but little is known on plants’ perspective. Finally, I wish to recommend further research on whether natural forest regeneration process should be altered in some forest patches in order to maintain some secondary forests

Identification of plant recognition receptors for nematode derived molecular patterns

Plant parasitic nematodes are pathogens of great economic importance causing major losses in various food crops world-wide. A reliable, effective and efficient control method is establishing resistant cultivars of which understanding plant defense against nematodes is the first step towards this solution. Plant defence relies on recognition of Pathogen-Associated Molecular Patterns (PAMPs) by surface-localised Pattern-Recognition Receptors (PRRs) prior to pathogen penetration. Upon PAMP perception, PRRs trigger intracellular signalling cascades leading to activation of PAMP-Triggered Immunity (PTI). PRRs perceiving a wide-range of PAMPs have now been characterized for various models of plant-pathogen interactions; however, even though Nematode derived PAMPs (NAMPS) such as ascarosides have been identified, none of their perceiving receptors have been characterized. Here we show that invasion of Arabidopsis roots by parasitic nematodes triggers PTI-like responses including an upregulation of defense related genes. Treating Arabidopsis roots with a nematode aqueous solution (NemaWater) similarly induced expression of defense genes. Among the upregulated genes were a number of plasma-membrane – localized Receptor-Like Kinases (RLKs) belonging to Leucine Rich Repeat (LRRs), Never In Mitosis A (NIMA) rElated Kinases (NEKs), Cysteine-Rich RLKs (CRKs) and Phytosulfokine Kinase (PSK) families. Nematode infection assays with candidate genes demonstrated that loss of NILR1 (for NEMATODE-INDUCED LRR-RLK 1) expression enhances the susceptibility of plants to a broad range of nematodes suggesting that NILR1 is a PRR that perceives a conserved nematode-derived NAMP. This finding is equally supported by experiments showing that nilr1 is defective in ROS burst as well as in seedling growth inhibition upon NemaWater treatment compared with wild-type control. In addition, presence ROS burst by NemaWater on rice plants suggested triggering of PTI by a NILR1 homologue in rice. We further showed AtNEK5 and NILR3 as potential NAMP receptors due to susceptibility of their knock out mutants to sedentary nematodes while two CRKs; CRK 19 and CRK10 portrayed roles in defense against nematodes in a species dependent manner. In addition, we demonstrated that the co-receptor BAK1 can be utilized to mine for potential receptors and signalling components involved in immunity against nematodes through successful BAK1-GFP pull down assay. The identification of NILR1 among others PRR perceiving NAMPs and successful baiting of BAK1 to pulldown nematode derived immunity components are major steps forward in understanding plant basal defense against nematodes. Consequently, these findings will not only increase knowledge into plant-nematode interaction but also pave way for further exploration of plant immunity studies. As a direct effect, the vital information from this study remains as a resource for molecular breeding of nematode resistant plants and a solution to yield loss due to nematode.Pflanzenparasitäre Nematoden sind Pathogene von großer ökonomischer Relevanz, da sie weltweit enorme Verluste in diversen Nutzpflanzensorten verursachen. Eine verlässliche, effektive und effiziente Regulierung ist die Verwendung resistenter Kultivare, wobei das Verständnis der Verteidigungsstrategien von Pflanzen gegen Nematoden ein erster Schritt zu dieser Lösung ist. Pflanzliche Verteidigungsstrategien beruhen auf der Erkennung sogenannter "Pathogen-Associated Molecular Patterns" (PAMPs) durch "Pattern-Recognition Receptors" (PRRs) bevor der Pathogen eindringt. Durch die Perzeption von PAMPs lösen PRRs intrazelluläre Signalkaskaden aus, die zur Aktivierung der PAMP-Triggered Immunity (PTI) führen. PRRs, die eine Viezahl von PAMPs erkennen, werden inzwischen in unterschiedlichen Modellen über die Planze-Pathogen Interaktionen beschrieben. Jedoch, obwohl nematodenbezogene PAMPs (NAMPs), wie zum Beispiel Ascaroside, identifiziert wurden, wurde bislang kein entsprechender Rezeptor charakterisiert. Hier zeigen wir, dass die Invasion von Arabidopsiswurzeln durch pflanzenparasitäre Nematoden PTI ähnliche Signale auslöst, einschließlich einer Hochregulation von Genen der Pflanzenabwehr. Die Behandlung von Arabidopsiswurzeln mit einer wässrigen Nematodenlösung (NemaWater) induziert auf eine ähnliche Weise die Expression von Abwehrgenen. Unter den hochregulierten Genen befinden sich eine Reihe "Receptor-Like Kinases" (RLKs) der Plasmamembran, die zu den Familien der "Leucine Rich Repeat (LRRs), Never In Mitosis A (NIMA) rElated Kinases (NEKs), Cysteine-Rich RLKs (CRKs)" und "Phytosulfokine Kinase" (PSK) gehören. Nematoden-Infektionsstudien demonstrierten, dass der Verlust des Kandidatengens NILR1 (for NEMATODE-INDUCED LRR-RLK 1), die Anfälligkeit der Pflanzen gegenüber einer Reihe von Nematodenarten erhöht. Dieses Ergebnis legt nahe, dass es sich bei NILR1 um ein NAMP erkennendes PRR handelt. Gleichzeitig wird diese Annahme durch Experimente unterstützt, die zeigen, dass die transgene Pflanze nilr1 eine beeinträchtigte ROS Ausschüttung sowie eine Hemmung des Keimlingswachstums nach Behandlng mit NemaWater aufweist. Zusätzlich suggerierte die ROS Ausschüttung in Reispflanzen durch NemaWater Behandlung, dass in diesem Fall ein NILR1 Homolog PTI auslöst. Außerdem zeigten wir, dass es sich bei AtNEK5 und NILR3 um potentielle NAMP Rezeptoren handelt, da die entsprechenden Knockout-Mutanten anfälliger gegenüber sedentären Nematoden waren, während die Rollen von CRKs; CRK 19 und CRK10, in speziesabhängigen Abwehrmechanismen vermutet werden. Zusätzlich konnten wir demonstrieren, dass der Korezeptor BAK1 in einer "GFP pull down" Analyse zur Suche nach potentiellen Rezeptoren und Signalkomponenten, involviert in Immunitätsmechanismen gegen Nematoden, verwendet werden kann. Die Identifizierung von NILR1 neben anderen PRR erkennenden NAMPs und das erfolgreiche Ködern von BAK1 zum Detektieren von nematodenbezogenen Immunitätskomponenten sind wichtige Schritte zu einem Verständnis der basalen Pflanzenabwehr gegen Nematoden. Folglich werden diese Erkenntnisse nicht nur das Wissen über die Pflanzen-Nematoden Interaktion bereichern, sondern auch den Weg ebnen für zukünftige Untersuchungen des Pflanzenimmunsystems. Als direkter Effekt stellt diese Studie eine Resource für molekulare Züchtung nematodenresistenter Pflanzen sowie eine Strategie zur Reduktion von Ernteausfällenn dar

Relationship Marketing And Customer Loyalty In Mobile Telecommunication Industry In Nairobi, Kenya

Relationship marketing is a strategy designed to build customer loyalty, interaction and customer long-term engagement through provision of information and open communication that suits customer needs. The broad objective of the study was to analyze the relationship between customer relationship marketing and customer loyalty in the mobile telecommunication industry in Nairobi, Kenya. The study employed a descriptive survey design. The population comprised individual customers of the four mobiletelecommunication companies in Kenya. A sample size of 384 respondents was utilized. Proportionate stratified sampling method based market share of each company was used.Primary data was collected using a semi-structured questionnaire while descriptive statistics and simple regression analysis was used to analyze the quantitative data. Thefindings were as follows, quality of a service is subjectively perceived by customers during the interactions with a firm and has critical impact on customers' evaluation of servicequality; effective communication of pricing policies as well as flexible pricing for various services offered play a great role in customer loyalty; positive brand image makes it easierfor a firm to convey its brand value to consumers and also generates favorable customer loyalty among people; Businesses operating in an intensely price based competitiveenvironment, dependent on high economies of scale and with low levels of staff-customer interaction are bound to suffer shocks in their market positions and profitability, Howeverlarge investments on relational strategies like building trust, commitment, communication and satisfaction can turnaround the shocks

Adoption and utilisation of Zai pits for improved farm productivity in drier upper Eastern Kenya

Inadequate and poorly distributed rainfall and declining soil fertility have led to low crop productivity in most smallholder farms in sub-Saharan Africa. As a result, there has been a renewed quest for sustainable and resource-use efficient agricultural production practices. Zai pit technology is a practice that has the potential to alleviate water stress and enhance soil fertility. We assessed the factors that influence farmers' adoption and utilisation of Zai pits in Tharaka-Nithi County in upper Eastern Kenya. We interviewed 291 farm household heads. Descriptive statistical analysis and a logistic regression model were applied to evaluate socio-economic factors that affect the adoption of Zai pits by farmers. Binary logistic regression estimation revealed that the number of non-formal training, beneficiaries of nongovernmental organisations, wealth status and membership of a social group play an essential role in the adoption of Zai pits. Based on the findings, we recommend that farm characteristics and socio-economic characteristics of farmers should be considered in the promotion of Zai pits as a water harvesting technology. The results of the study will be useful to extension service providers in planning, designing and evaluating effective and efficient agricultural policies, programs and projects at local, regional and national scales in the dissemination of Zai pit technology among smallholder farmers in the semi-arid tropics

Prevalence and correlates of bacterial vaginosis in different sub-populations of women in Sub-Saharan Africa: a cross-sectional study

Background: Clinical development of vaginally applied products aimed at reducing the transmission of HIV and other sexually transmitted infections, has highlighted the need for a better characterisation of the vaginal environment. We set out to characterise the vaginal environment in women in different settings in sub-Saharan Africa. Methods: A longitudinal study was conducted in Kenya, Rwanda and South-Africa. Women were recruited into pre-defined study groups including adult, non-pregnant, HIV-negative women; pregnant women; adolescent girls; HIV-negative women engaging in vaginal practices; female sex workers; and HIV-positive women. Consenting women were interviewed and underwent a pelvic exam. Samples of vaginal fluid and a blood sample were taken and tested for bacterial vaginosis (BV), HIV and other reproductive tract infections (RTIs). This paper presents the cross-sectional analyses of BV Nugent scores and RTI prevalence and correlates at the screening and the enrolment visit. Results: At the screening visit 38% of women had BV defined as a Nugent score of 7-10, and 64% had more than one RTI (N. gonorrhoea, C. trachomatis, T. vaginalis, syphilis) and/or Candida. At screening the likelihood of BV was lower in women using progestin-only contraception and higher in women with more than one RTI. At enrolment, BV scores were significantly associated with the presence of prostate specific antigen (PSA) in the vaginal fluid and with being a self-acknowledged sex worker. Further, sex workers were more likely to have incident BV by Nugent score at enrolment. Conclusions: Our study confirmed some of the correlates of BV that have been previously reported but the most salient finding was the association between BV and the presence of PSA in the vaginal fluid which is suggestive of recent unprotected sexual intercourse

Arabidopsis leucine-rich repeat receptor–like kinase NILR1 is required for induction of innate immunity to parasitic nematodes

Plant-parasitic nematodes are destructive pests causing losses of billions of dollars annually. An effective plant defence against pathogens relies on the recognition of pathogen-associated molecular patterns (PAMPs) by surface-localised receptors leading to the activation of PAMP-triggered immunity (PTI). Extensive studies have been conducted to characterise the role of PTI in various models of plant-pathogen interactions. However, far less is known about the role of PTI in roots in general and in plant-nematode interactions in particular. Here we show that nematode-derived proteinaceous elicitor/s is/are capable of inducing PTI in Arabidopsis in a manner dependent on the common immune co-receptor BAK1. Consistent with the role played by BAK1, we identified a leucine-rich repeat receptor-like kinase, termed NILR1 that is specifically regulated upon infection by nematodes. We show that NILR1 is essential for PTI responses initiated by nematodes and nilr1 loss-of-function mutants are hypersusceptible to a broad category of nematodes. To our knowledge, NILR1 is the first example of an immune receptor that is involved in induction of basal immunity (PTI) in plants or in animals in response to nematodes. Manipulation of NILR1 will provide new options for nematode control in crop plants in future

Phenotypic Characterization of EIF2AK4 Mutation Carriers in a Large Cohort of Patients Diagnosed Clinically With Pulmonary Arterial Hypertension.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a rare disease with an emerging genetic basis. Heterozygous mutations in the gene encoding the bone morphogenetic protein receptor type 2 (BMPR2) are the commonest genetic cause of PAH, whereas biallelic mutations in the eukaryotic translation initiation factor 2 alpha kinase 4 gene (EIF2AK4) are described in pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis. Here, we determine the frequency of these mutations and define the genotype-phenotype characteristics in a large cohort of patients diagnosed clinically with PAH. METHODS: Whole-genome sequencing was performed on DNA from patients with idiopathic and heritable PAH and with pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis recruited to the National Institute of Health Research BioResource-Rare Diseases study. Heterozygous variants in BMPR2 and biallelic EIF2AK4 variants with a minor allele frequency of <1:10 000 in control data sets and predicted to be deleterious (by combined annotation-dependent depletion, PolyPhen-2, and sorting intolerant from tolerant predictions) were identified as potentially causal. Phenotype data from the time of diagnosis were also captured. RESULTS: Eight hundred sixty-four patients with idiopathic or heritable PAH and 16 with pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis were recruited. Mutations in BMPR2 were identified in 130 patients (14.8%). Biallelic mutations in EIF2AK4 were identified in 5 patients with a clinical diagnosis of pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis. Furthermore, 9 patients with a clinical diagnosis of PAH carried biallelic EIF2AK4 mutations. These patients had a reduced transfer coefficient for carbon monoxide (Kco; 33% [interquartile range, 30%-35%] predicted) and younger age at diagnosis (29 years; interquartile range, 23-38 years) and more interlobular septal thickening and mediastinal lymphadenopathy on computed tomography of the chest compared with patients with PAH without EIF2AK4 mutations. However, radiological assessment alone could not accurately identify biallelic EIF2AK4 mutation carriers. Patients with PAH with biallelic EIF2AK4 mutations had a shorter survival. CONCLUSIONS: Biallelic EIF2AK4 mutations are found in patients classified clinically as having idiopathic and heritable PAH. These patients cannot be identified reliably by computed tomography, but a low Kco and a young age at diagnosis suggests the underlying molecular diagnosis. Genetic testing can identify these misclassified patients, allowing appropriate management and early referral for lung transplantation

Telomerecat: A ploidy-agnostic method for estimating telomere length from whole genome sequencing data.

Telomere length is a risk factor in disease and the dynamics of telomere length are crucial to our understanding of cell replication and vitality. The proliferation of whole genome sequencing represents an unprecedented opportunity to glean new insights into telomere biology on a previously unimaginable scale. To this end, a number of approaches for estimating telomere length from whole-genome sequencing data have been proposed. Here we present Telomerecat, a novel approach to the estimation of telomere length. Previous methods have been dependent on the number of telomeres present in a cell being known, which may be problematic when analysing aneuploid cancer data and non-human samples. Telomerecat is designed to be agnostic to the number of telomeres present, making it suited for the purpose of estimating telomere length in cancer studies. Telomerecat also accounts for interstitial telomeric reads and presents a novel approach to dealing with sequencing errors. We show that Telomerecat performs well at telomere length estimation when compared to leading experimental and computational methods. Furthermore, we show that it detects expected patterns in longitudinal data, repeated measurements, and cross-species comparisons. We also apply the method to a cancer cell data, uncovering an interesting relationship with the underlying telomerase genotype

Phenotypic Characterization of <i>EIF2AK4</i> Mutation Carriers in a Large Cohort of Patients Diagnosed Clinically With Pulmonary Arterial Hypertension

Background: Pulmonary arterial hypertension (PAH) is a rare disease with an emerging genetic basis. Heterozygous mutations in the gene encoding the bone morphogenetic protein receptor type 2 ( BMPR2 ) are the commonest genetic cause of PAH, whereas biallelic mutations in the eukaryotic translation initiation factor 2 alpha kinase 4 gene ( EIF2AK4 ) are described in pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis. Here, we determine the frequency of these mutations and define the genotype-phenotype characteristics in a large cohort of patients diagnosed clinically with PAH. Methods: Whole-genome sequencing was performed on DNA from patients with idiopathic and heritable PAH and with pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis recruited to the National Institute of Health Research BioResource–Rare Diseases study. Heterozygous variants in BMPR2 and biallelic EIF2AK4 variants with a minor allele frequency of &lt;1:10 000 in control data sets and predicted to be deleterious (by combined annotation-dependent depletion, PolyPhen-2, and sorting intolerant from tolerant predictions) were identified as potentially causal. Phenotype data from the time of diagnosis were also captured. Results: Eight hundred sixty-four patients with idiopathic or heritable PAH and 16 with pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis were recruited. Mutations in BMPR2 were identified in 130 patients (14.8%). Biallelic mutations in EIF2AK4 were identified in 5 patients with a clinical diagnosis of pulmonary veno-occlusive disease/pulmonary capillary hemangiomatosis. Furthermore, 9 patients with a clinical diagnosis of PAH carried biallelic EIF2AK4 mutations. These patients had a reduced transfer coefficient for carbon monoxide (K co ; 33% [interquartile range, 30%–35%] predicted) and younger age at diagnosis (29 years; interquartile range, 23–38 years) and more interlobular septal thickening and mediastinal lymphadenopathy on computed tomography of the chest compared with patients with PAH without EIF2AK4 mutations. However, radiological assessment alone could not accurately identify biallelic EIF2AK4 mutation carriers. Patients with PAH with biallelic EIF2AK4 mutations had a shorter survival. Conclusions: Biallelic EIF2AK4 mutations are found in patients classified clinically as having idiopathic and heritable PAH. These patients cannot be identified reliably by computed tomography, but a low K co and a young age at diagnosis suggests the underlying molecular diagnosis. Genetic testing can identify these misclassified patients, allowing appropriate management and early referral for lung transplantation. </jats:sec