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Search Results: 1 - 10 of 404847 matches for " Henry M. Kariithi "
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The Salivary Secretome of the Tsetse Fly Glossina pallidipes (Diptera: Glossinidae) Infected by Salivary Gland Hypertrophy Virus
Henry M. Kariithi,Ikbal A. Ince,Sjef Boeren,Adly M. M. Abd-Alla,Andrew G. Parker,Serap Aksoy,Just M. Vlak ,Monique M. van Oers
PLOS Neglected Tropical Diseases , 2011, DOI: 10.1371/journal.pntd.0001371
Abstract: Background The competence of the tsetse fly Glossina pallidipes (Diptera; Glossinidae) to acquire salivary gland hypertrophy virus (SGHV), to support virus replication and successfully transmit the virus depends on complex interactions between Glossina and SGHV macromolecules. Critical requisites to SGHV transmission are its replication and secretion of mature virions into the fly's salivary gland (SG) lumen. However, secretion of host proteins is of equal importance for successful transmission and requires cataloging of G. pallidipes secretome proteins from hypertrophied and non-hypertrophied SGs. Methodology/Principal Findings After electrophoretic profiling and in-gel trypsin digestion, saliva proteins were analyzed by nano-LC-MS/MS. MaxQuant/Andromeda search of the MS data against the non-redundant (nr) GenBank database and a G. morsitans morsitans SG EST database, yielded a total of 521 hits, 31 of which were SGHV-encoded. On a false discovery rate limit of 1% and detection threshold of least 2 unique peptides per protein, the analysis resulted in 292 Glossina and 25 SGHV MS-supported proteins. When annotated by the Blast2GO suite, at least one gene ontology (GO) term could be assigned to 89.9% (285/317) of the detected proteins. Five (~1.8%) Glossina and three (~12%) SGHV proteins remained without a predicted function after blast searches against the nr database. Sixty-five of the 292 detected Glossina proteins contained an N-terminal signal/secretion peptide sequence. Eight of the SGHV proteins were predicted to be non-structural (NS), and fourteen are known structural (VP) proteins. Conclusions/Significance SGHV alters the protein expression pattern in Glossina. The G. pallidipes SG secretome encompasses a spectrum of proteins that may be required during the SGHV infection cycle. These detected proteins have putative interactions with at least 21 of the 25 SGHV-encoded proteins. Our findings opens venues for developing novel SGHV mitigation strategies to block SGHV infections in tsetse production facilities such as using SGHV-specific antibodies and phage display-selected gut epithelia-binding peptides.
Virology, Epidemiology and Pathology of Glossina Hytrosavirus, and Its Control Prospects in Laboratory Colonies of the Tsetse Fly, Glossina pallidipes (Diptera; Glossinidae)
Henry M. Kariithi,Monique M. van Oers,Just M. Vlak,Marc J. B. Vreysen,Andrew G. Parker,Adly M. M. Abd-Alla
Insects , 2013, DOI: 10.3390/insects4030287
Abstract: The Glossina hytrosavirus (family Hytrosaviridae) is a double-stranded DNA virus with rod-shaped, enveloped virions. Its 190 kbp genome encodes 160 putative open reading frames. The virus replicates in the nucleus, and acquires a fragile envelope in the cell cytoplasm. Glossina hytrosavirus was first isolated from hypertrophied salivary glands of the tsetse fly, Glossina pallidipes Austen (Diptera; Glossinidae) collected in Kenya in 1986. A certain proportion of laboratory G. pallidipes flies infected by Glossina hytrosavirus develop hypertrophied salivary glands and midgut epithelial cells, gonadal anomalies and distorted sex-ratios associated with reduced insemination rates, fecundity and lifespan. These symptoms are rare in wild tsetse populations. In East Africa, G. pallidipes is one of the most important vectors of African trypanosomosis, a debilitating zoonotic disease that afflicts 37 sub-Saharan African countries. There is a large arsenal of control tactics available to manage tsetse flies and the disease they transmit. The sterile insect technique (SIT) is a robust control tactic that has shown to be effective in eradicating tsetse populations when integrated with other control tactics in an area-wide integrated approach. The SIT requires production of sterile male flies in large production facilities. To supply sufficient numbers of sterile males for the SIT component against G. pallidipes, strategies have to be developed that enable the management of the Glossina hytrosavirus in the colonies. This review provides a historic chronology of the emergence and biogeography of Glossina hytrosavirus, and includes researches on the infectomics (defined here as the functional and structural genomics and proteomics) and pathobiology of the virus. Standard operation procedures for viral management in tsetse mass-rearing facilities are proposed and a future outlook is sketched.
Transgenerational Transmission of the Glossina pallidipes Hytrosavirus Depends on the Presence of a Functional Symbiome
Drion G. Boucias, Henry M. Kariithi, Kostas Bourtzis, Daniela I. Schneider, Karen Kelley, Wolfgang J. Miller, Andrew G. Parker, Adly M. M. Abd-Alla
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0061150
Abstract: The vertically transmitted endosymbionts (Sodalis glossinidius and Wigglesworthia glossinidia) of the tsetse fly (Diptera: Glossinidae) are known to supplement dietary deficiencies and modulate the reproductive fitness and the defense system of the fly. Some tsetse fly species are also infected with the bacterium, Wolbachia and with the Glossina hytrosavirus (GpSGHV). Laboratory-bred G. pallidipes exhibit chronic asymptomatic and acute symptomatic GpSGHV infection, with the former being the most common in these colonies. However, under as yet undefined conditions, the asymptomatic state can convert to the symptomatic state, leading to detectable salivary gland hypertrophy (SGH+) syndrome. In this study, we investigated the interplay between the bacterial symbiome and GpSGHV during development of G. pallidipes by knocking down the symbionts with antibiotic. Intrahaemocoelic injection of GpSGHV led to high virus titre (109 virus copies), but was not accompanied by either the onset of detectable SGH+, or release of detectable virus particles into the blood meals during feeding events. When the F1 generations of GpSGHV-challenged mothers were dissected within 24 h post-eclosion, SGH+ was observed to increase from 4.5% in the first larviposition cycle to >95% in the fourth cycle. Despite being sterile, these F1 SGH+ progeny mated readily. Removal of the tsetse symbiome, however, suppressed transgenerational transfer of the virus via milk secretions and blocked the ability of GpSGHV to infect salivary glands of the F1 progeny. Whereas GpSGHV infects and replicates in salivary glands of developing pupa, the virus is unable to induce SGH+ within fully differentiated adult salivary glands. The F1 SGH+ adults are responsible for the GpSGHV-induced colony collapse in tsetse factories. Our data suggest that GpSGHV has co-evolved with the tsetse symbiome and that the symbionts play key roles in the virus transmission from mother to progeny.
Managing Hytrosavirus Infections in Glossina pallidipes Colonies: Feeding Regime Affects the Prevalence of Salivary Gland Hypertrophy Syndrome
Adly M. M. Abd-Alla, Henry M. Kariithi, Abdul Hasim Mohamed, Edgardo Lapiz, Andrew G. Parker, Marc J. B. Vreysen
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0061875
Abstract: Many species of tsetse flies are infected by a virus that causes salivary gland hypertrophy (SGH) syndrome and the virus isolated from Glossina pallidipes (GpSGHV) has recently been sequenced. Flies with SGH have a reduced fecundity and fertility. Due to the deleterious impact of SGHV on G. pallidipes colonies, several approaches were investigated to develop a virus management strategy. Horizontal virus transmission is the major cause of the high prevalence of the GpSGHV in tsetse colonies. Implementation of a “clean feeding” regime (fresh blood offered to each set of flies so that there is only one feed per membrane), instead of the regular feeding regime (several successive feeds per membrane), was among the proposed approaches to reduce GpSGHV infections. However, due to the absence of disposable feeding equipment (feeding trays and silicone membranes), the implementation of a clean feeding approach remains economically difficult. We developed a new clean feeding approach applicable to large-scale tsetse production facilities using existing resources. The results indicate that implementing this approach is feasible and leads to a significant reduction in virus load from 109 virus copies in regular colonies to an average of 102.5 and eliminates the SGH syndrome from clean feeding colonies by28 months post implementation of this approach. The clean feeding approach also reduced the virus load from an average of 108 virus copy numbers to an average of 103 virus copies and SGH prevalence of 10% to 4% in flies fed after the clean fed colony. Taken together, these data indicate that the clean feeding approach is applicable in large-scale G. pallidipes production facilities and eliminates the deleterious effects of the virus and the SGH syndrome in these colonies.
Rift Valley Fever Risk Map Model and Seroprevalence in Selected Wild Ungulates and Camels from Kenya
Seth C. Britch, Yatinder S. Binepal, Mark G. Ruder, Henry M. Kariithi, Kenneth J. Linthicum, Assaf Anyamba, Jennifer L. Small, Compton J. Tucker, Leonard O. Ateya, Abuu A. Oriko, Stephen Gacheru, William C. Wilson
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0066626
Abstract: Since the first isolation of Rift Valley fever virus (RVFV) in the 1930s, there have been multiple epizootics and epidemics in animals and humans in sub-Saharan Africa. Prospective climate-based models have recently been developed that flag areas at risk of RVFV transmission in endemic regions based on key environmental indicators that precede Rift Valley fever (RVF) epizootics and epidemics. Although the timing and locations of human case data from the 2006–2007 RVF outbreak in Kenya have been compared to risk zones flagged by the model, seroprevalence of RVF antibodies in wildlife has not yet been analyzed in light of temporal and spatial predictions of RVF activity. Primarily wild ungulate serum samples from periods before, during, and after the 2006–2007 RVF epizootic were analyzed for the presence of RVFV IgM and/or IgG antibody. Results show an increase in RVF seropositivity from samples collected in 2007 (31.8%), compared to antibody prevalence observed from 2000–2006 (3.3%). After the epizootic, average RVF seropositivity diminished to 5% in samples collected from 2008–2009. Overlaying maps of modeled RVF risk assessments with sampling locations indicated positive RVF serology in several species of wild ungulate in or near areas flagged as being at risk for RVF. Our results establish the need to continue and expand sero-surveillance of wildlife species Kenya and elsewhere in the Horn of Africa to further calibrate and improve the RVF risk model, and better understand the dynamics of RVFV transmission.
New Media Development in Africa
Isaac Esipisu,Nixon Kariithi
Global Media Journal : African Edition , 2011, DOI: 10.5789/1-1-45
Abstract: In this paper we give an exploratory overview of how the new media has developed in Africa and the role that new media technologies might play in facilitating the development of media in African countries.
Riemann and Euler Sum Investigation in an Introductory Calculus Class  [PDF]
Michael M. Henry, Dennis M. Cates
Open Journal of Discrete Mathematics (OJDM) , 2011, DOI: 10.4236/ojdm.2011.12007
Abstract: This paper provides a detailed outline of a mathematical research exploration for use in an introductory high school or college Calculus class and is directed toward teachers of such courses. The discovery is accomplished by introducing a novel method to generate a polynomial expression for each of the Euler sums, ΣNk=0kn,n∈Z+ . The described method flows simply from initial discussions of the Riemann sum definition of a definite integral and is readily accessible to all new calculus students. Students investigate the Bernoulli numbers and the interesting connections with Pascal's Triangle. Advice is offered throughout as to how the project can be assigned to students and offers multiple suggestions for additional exploration for any motivated student.
An Analysis of Fights in the National Hockey League  [PDF]
Henry L. Castillo, Paul M. Sommers
Open Journal of Statistics (OJS) , 2017, DOI: 10.4236/ojs.2017.74047
Abstract: The authors use data from fight logs during the 2016-2017 regular National Hockey League (NHL) season to test for a difference in the proportion of games with and without fights for each of the thirty NHL teams. Only one team (Toronto Maple Leafs) was more likely to be involved in a fight at a home game than at an away game. Teams that fought proportionally more often in the second half of the season made the playoffs; teams that fought significantly less often did not. And, long distance air travel (flights involving more than 1000 miles or trips that required crossing at least one time zone) resulted in disproportionately more games with fights for eight different NHL teams.
Seabed Identification and Characterization Using Sonar
Henry M. Manik
Advances in Acoustics and Vibration , 2012, DOI: 10.1155/2012/532458
Abstract: Application of sonar technologies to bottom acoustics study has made significant advances over recent decades. The sonar systems evolved from the simple analog single-beam and single-frequency systems to more sophisticated digital ones. In this paper, a quantified sonar system was applied to detect and quantify the bottom echoes. The increasing of mean diameter is accompanied by a higher backscattering strength. From this study, identification and characterization using sonar is possible. 1. Introduction Sonar technologies are most effective and useful for sea-bottom exploration. They are based mainly on the measurement, process, analysis, and interpretation of the characteristics of signal reflected or scattered by the sea bottom. Sonar is also increasingly regarded as the remote-sensing tool that will provide the basis for identification, classifying, and mapping ocean resources. There are extensive literatures on the acoustic scattering from the sea bottom [1, 2]. The focus has been on low-frequency features in application such as subbottom classification [3]. Another feature of the sea-bottom scattering has been experimentally observed at a high frequency where the transmitter and receiver are not colocated [4]. This method received contributions both from the bottom surface and subbottom echoes. Most of the data were at grazing angles between 5° and 60°, but some data were collected for the interval between 1° and normal incidence (90°). They obtained results similar to those of Urick [1]. One of the acoustic methods to obtain bottom scattering is to use a quantified sonar system (QSS). The QSS can measure echoes generated by reflection and scattering of sounding pulses from the bottom. The observed echo is primarily due to scattering from the water-bottom interface. 2. Method 2.1. Sonar Equation for Bottom Scattering The bottom projection is illustrated in Figure 1. The elemental backscattered power registered by the transducer is given by where is elemental backscattered pressure signal from a sea bottom, is source pressure level, is range, is absorption coefficient, is directivity functions, and is bottom scattering. The elemental area is located at incidence angle , azimuthal angle , and range , such that The echo pressure amplitude of sea bottom is obtained by integration of (1): where is equivalent beam angle for surface scattering The length of pulse in sea water is , and its leading and trailing edges make angles and as presented in Table 1. Table 1: Integration limits and for two cases. Figure 1: Principle of bottom surface scattering. The
Towards Identifying Current Strategies and Innovative Approaches for the Growth of Dairy Goat Entrepreneurs: A Case Study of Njiru District, Kenya
Philemon Lagat,Henry M. Bwisa
International Journal of Academic Research in Business and Social Sciences , 2012,
Abstract: Dairy goats remain to be the most lucrative business where land fragmentation has resulted in the formation of small pieces of land that cannot support dairy cattle farming (Kinyanjui et al., 2008). From casual observation, this situation does not prevail in Njiru District since the growth is very slow hence the venture is risky. Nevertheless, some few farmers have risked by taking the initiative of venturing into the business so as to seize the opportunity. The purpose of this study was to identify current strategies and innovative approaches for the growth of dairy goat entrepreneurs.The population of this study was determined by getting a list of farmers engaged in micro and small dairy goat enterprises. This constituted the sampling frame. Simple random sampling method was used to select 36 dairy goat farmers from a list of dairy goat enterprises in Njiru District. The questionnaire comprised of closed and open ended questions. Descriptive statistics was used to collect data and included frequency tables. Further, a computer statistical package for social sciences (SPSS) was used in entering and analyzing the data. The study established that the entrepreneurs adopted innovative approaches in their businesses. All of the respondents claimed that their businesses had increased in growth as a result of adopting current strategies and innovative approaches in their dairy goat enterprises.
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