Ogembo Javier

Javier Gordon Ogembo born (August 22, 1974 in Kendu Bay,Nyanza Province, Kenya). He is fondly known as Orinda Sibuor amongst his friends in Kenya, and as Gordon amongst his friends outside Kenya. Ogembo was born to the late Charles Ogembo Okun formerly of Ogembo Building and General Constructors, Mombasa, Kenya and Mrs. Penina Aoko Ogembo. He was born in a family of six sisters and one brother, the Late Tom Mboya. His father had a second wife, Mary Auma Ogembo with whom they had other six children. Ogembo married his beautiful wife Rebecca Kemunto Ogembo (Becky) on the 23^rd, January 2005, in Japan. Becky is Ogembo's best and closest friend.

Education

After graduating from Kanyawanga High School, Ogembo studied at Egerton University, where he majored in Bsc. Horticulture, with special interest in insect pest management. During his study period, Ogembo worked as a temporary staff with Barclays Bank Kenya Limited. He received his Bsc degree in 2000, then worked for one year at the International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya. He then proceeded for Msc in Tropical Entomology at the University of Zimbabwe after receiving African Regional Post Graduate Scholarship (ARPPIS) from ICIPE, founded by the late Prof. Thomas Risley Odhiambo who is one of his scientific and leadership mentor. He later joined Horticulture Research International, Wellesboune, UK as a visiting scientist, in Dr. Doreen Winstanley laboratory. After learning virological techniques applied in insect pest management, Ogembo returned to Kenya to join ICIPE once again as an intern in Vegetable IPM project, under Dr. Srinivisan Sithanantham. After six months internship, Ogembo joined the Witwatersrand University, Johannesburg, South Africa as a research fellow and later joined Nagoya University, Japan for a PhD program after receiving the prestigious Japanese Government Scholarship (Monbukagusho). His research interest is biodynamics of insect virus (Baculovirus) interactions with their insect host, under Prof. Michihiro Kobayashi. This laboratory is involved in studies aiming at understanding the molecular, cellular and physiological basis of viral pathogenesis in insects, with particular interest in the mechanism of host range determination of the viruses both "in vivo" and "in vitro". One of the objectives of his studies is to develop effective and safe viral pesticides through cloning and selection of virulent virus strain and use genetic engineering to improve their efficacy. Ogembo has devoted his work studying African bollworm, "Helicoverpa armigera" nucleopolyhedrovirus isolates from Africa mainly from Kenya, Zimbabwe and South Africa. He has also worked with other nucleopolyhedroviruses such as "Autographa californica" (AcMNPV), "Hyphantria cunea" (HycuNPV), "Spodoptera litura" (SpltNPV), "Orgyia pseudotsugata" (OpMNPV), "Bombyx mori" (BmNPV), "Spodoptera exigua" (SeMNPV) and "Lymantria dispar" (LdMPV). Ogembo is currently researching on the mechanisms of nucleopolyhedroviruses infection, DNA and viral proteins synthesis in different insects and insect cell lines. He is interested in identifying NPVs genes that causes strain virulence variations and host range determination.

Research interest

Agricultural production in Kenya is facing myriad problems and leading among them is the over-reliance on chemical pesticides to control insect pests and diseases. The primary problems with synthetic pesticides include cost, detrimental effects on non-target organisms, development of insect resistance and chemical residues on the crop produce. A significant number of lepidopteran insect pests including African bollworm, "Helicoverpa armigera", stem borer, "Buseola fusca", larger grain borer, "Prostephanus truncates", cabbage moth "Plutella xyolostella", armyworm, Spodoptera spp. have been identified as the key pests to major agricultural crops in Kenya. Some of these insects, particularly "H. armigera" and "P. xyllostella" have been reported to develop resistance to most chemical pesticides currently applied in the field. Baculoviruses which are arthropod-specific viruses have been identified in more than 520 insect species predominantly from the order Lepidoptera, as well as in Hymenoptera and Diptera. These viruses cause natural epizootics in the field where insect pests are reported. Careful biological characterization through cloning and selection of isolates with higher insecticidal activities against insect larvae, well developed efficient method of mass production of selected clones coupled with correct timely application can offer a solution to chemical residue related problems, especially as an alternative to purely synthetic chemical crop protection.　

The family Baculoviridae is a large rod-shaped viruses with circular, covalently closed, double stranded DNA genomes of 80-180 kbp. The family is divided into two genera, nucleopolyhedroviruses (NPV) and granuloviruses (GV). While GVs contain only one nucleocapsid envelope NPVs contain either single (SNPV) or multiple (MNPV) nucleocapsids per envelope. The enveloped virions are further occluded in granulin matrix in GVs and polyhedrin for NPVs.

Baculovirus replication cycle

Baculovirus exhibits a unique replication cycle, yielding two distinct forms that are genotypically identical but differs in morphology, time of maturation, structure, antigenicity and infectivity. One form is occlusion derived virions (ODV) that mature within the nucleus of infected cells and are occluded in a protein matrices designated as polyhedra. The other is budded virions (BV) that mature through budding from the plasma membrane of infected cells. Typically, the initial infection occurs when a susceptible host insect larva feeds on plants that are contaminated with the occluded form of the virus. The protein matrix is dissolved by the alkaline juices of the host midgut (stomach), releasing ODV that then fuse to the columnar epithelial cell membrane of the host intestine and are taken into the cell in endosomes causing primary infection. Nucleocapsids escape from the endosomes and are transported to nucleus. Viral transcription and replication occur in the cell nucleus and new BV particles are budded out from the basolateral side primarily as single nucleocapsids into haemocoel to subsequently spread secondary infection systemically. During budding, BVs enter cells via adsorptive endocytosis in which viral glycoproteins GP64 or F-protein of group I and II, respectively, plays a crucial role. In the endocytotic pathway, BV virions bind to the host cells and are uptaken into endocytic pathway vesicle-endosomes. The endosomes with the viral cargo travel to the vicinity of the nucleus, where low pH-triggered membrane fusion occurs between BV envelopes and endosomal membranes to release viral nucleocapsid into the cytoplasm of the host cells. Upon release of the nucleocapsid from the endosomes, filamentous actin cables are formed in the cytoplasm, through which viral genome DNA with associated capsid proteins is transported into the nucleus. Once the viral genome is in the nucleus in an expressible form, baculovirus temporally initiates a cascade of gene expression at early, late and very late times postinfection. However, some genes can be expressed in more than one phase of the replication cycle. Control of the expression is mainly by the promoter region of the gene. Genes having promoter elements with strong similarity to insect promoters tend to be expressed early in the infection, whereas genes with specific viral promoter sequences tend to be expressed during the later phases of the replication cycle.

Early phase of baculoviruses infection

During the early phase of infection genes involved in the regulation of the replication cascade (IE-0, IE-1, IE-2, PE-38) and those involved in preventing host responses are expressed (e.g. p35). The genes expressed in the early phase of infection and replication can be divided into immediate early and delayed early. The immediate early genes do not require viral transregulators for efficient expression and include the transregulators (IE-1, IE-2). The delayed early genes are characterized by the requirement of a transregulator for efficient transcription.Genes required for DNA synthesis [DNA polymerase (dnapol) and a DNA helicase-like protein (p143)] and factors involved in late gene expression (e.g. lefs - late expression factors) are also expressed in the early phase. A number of genes which modify aspects of the intra- and extracellular environment are also expressed at this stage. The enzyme EGT is produced to modify the extracellular environment and p35 (as well as various inhibitors or apoptosis (IAPs) is produced to prevent apoptosis.The early genes of the baculovirus are transcribed by a host RNA polymerase, however many of the early promoters also require the regulatory protein IE-1 (or IE-0) for efficient transcription. Early genes have variable transcription patterns. The transcripts of some are present as early as 1 hour post-infection (h.p.i.) and decline quickly (by 6 h.p.i.), whereas others accumulate with time. This difference in the presence of transcripts may reflect the roles of the various early proteins and the presence of a late promoter motif. The timing of the transcripts varies between viruses and also depends on the species of host that the virus is infecting. The late phase of baculovirus replication begins at approximately 6 h p.i. and extends through to about 24 h p.i. The features of this phase include the replication of the viral DNA, the shutdown of host cell transcription and translation and the production of the budded form of the virus. Proteins produced in this phase include the DNA binding protein p6.9 (involved in DNA packaging) and GP64　or F-protein (envelope fusion protein found on the surface of the budded virus). The switch from early to late gene expression involves a change in the RNA polymerase used for the transcription of genes. The polymerase utilized in this phase is a virally encoded RNA polymerase. This form of polymerase recognizes a different promoter sequence (TAAG) to the sequences recognized in the early phase of replication (TATA-like and/or CAGT motifs).

Late phase of baculoviruses infection

One of the key features of the late phase is the replication of the genome. This replication is thought to originate at the homologous region (hr) sequences and proceed around the genome. This method of DNA replication is referred to a rolling circle method. Baculoviruses hr are located along the genome allowing DNApol to bind at multiple sites and thus replicate the genome in the most efficient way.Nucloecapsids are also formed during the late phase. This involves the production of the helical nucleocapsids and the packaging of the viral DNA. Packaging of the viral DNA requires the dephosphorylation of p6.9. The fate of the nucleocapsids is variable. They can either bud out through the cellular membrane and/or disseminate the infection within the insect by infecting other cells by GP64/F-proetin mediated envelope fusion and subsequent endocytosis, or be occluded for horizontal transmission.The very late phase of replication also called the occlusion phase. The virus becomes occluded in the protein polyhedrin and the polyhedral envelope (calyx) is produced in this phase. The final stages of this phase involve the lysis of the cell and release of the occluded virus. This lysis results in the death and liquefaction of the host. The viral proteins cathepsin and chitinase are involved in the liquefaction process. Cathepsin breaks down the membranes and cell walls within the insect while the chitinase degrades the chitin in the exoskeleton of the larvae.Baculovirus infection can be divided to three distinct phases, early (0-6 h post-infection), late (6-24 h p.i.) and very late phase (18-24 to 72 h p.i.). While BV is produced in the late phase, the ODV form is produced in the very late phase acquiring the envelope from host cell nucleus and embedded in the matrix of occlusion body protein. These occlusion bodies are released when cells lyse to further spread baculovirus infection to next host. The extensive lysis of cells frequently causes the host insect to literally melt, thus the reason for the historic name "wilting disease." To adapt survival in the wild, ODV-polyhedrin particles are resistant to heat and light inactivation, whereas BV is more sensitive to environment.

Publications"'

1.Mireji, P.O., Mabveni, A.M., Dube, B.N., Ogembo, J.G., Matoka, C.M. and Mangwiro, T.N.C. (2003). Field responses of tsetse flies (Glossinidae) and other Dipteras to oil in formulations of deltermethrin. J. Insect Sci. Applic. 23, 317-323.

2.Ogembo, J.G., Kunjeku, E.C. and Sithanantham, S. (2005). A preliminary study on the pathogenicity of two isolates of nucleopolyhedroviruses infecting African bollworm, Helicoverpa armigera Hübner (Lepidoptera: Noctuidae). Int. J. Trop. Insect Sci. 25, 218-222.

3.Ogembo, J.G., Chaeychomsri, S., Kamiya, K., Ishikawa, H., Katou, Y., Ikeda, M. and Kobayashi, M. (2007). Cloning and comparative characterization of nucleopolyhedrovirus isolated from African bollworm, Helicoverpa armigera, (Lepidoptera: Noctuidae) in different regions. J. Insect Biotechnol. Sericol.76, 39-49.

4.Ogembo, J.G., Chaeychomsri, S., Caoili, B.L., Ikeda, M. and Kobayashi, M. (2008). Susceptibility of newly established cell lines from Helicoverpa armigera against homologous and heterologous nucleopolyhedroviruses. J. Insect Biotechnol. Sericol. 77, 25-34.

5.Ogembo, J.G., Chaeychomsri, S., Ikeda, M., Caoili, B.L., and Kobayashi, M. (2008). Susceptibility of the cell line Hv-AM1 from Heliothis virescens to eight selected nucleopolyhedroviruses. Submitted.

6.Ogembo, J.G., Shikata, M., Chaeychomsri, S., Caoili, B.L., Kobayashi, M. and Ikeda, M. (2008). Gene organization and complete sequence of Helicoverpa armigera nucleopolyhedrovirus genome from Kenya. Manuscript in preparation.

Reformist

Ogembo is a reformist and has frequently advocated for free and better education for all. His main interest is to help many Kenyans and people from developing world to get quality free education, which he believes will help them fight poverty that has permeated the society. He believes this can be achieved only when everyone in the society plays their role effectively, and more so where there is fairness in the distribution of resources.

Sambaza Group

Ogembo helped found the Sambaza Group with his friend Matthew John Pelowski from the USA, Sambaza Group is a non-governmental organization based in Japan and Kenya, helping in connecting primary schools and rural community learning centers with Internet through donation and installation of computers in primary schools. He now sits in the board of management of the same organization as a co-president with Matthew Pelowski.

At sambaza Group, it is our ultimate goal to use the computer and computer-based training to provide East African communities with the technology skills necessary for mastery of the computer and with a new attitude toward technology which will aid future technology transfer and mastery. indeed, the world of the future, and the present, is built on Internet Communication Technology. The ability to embrace advances and concepts in the international community in turn requires a basic understanding of current technology. It remains an enormous task for ordinary people to better their lives without this technology, yet, primary schools across East Africa are still without basic computers, and East African children are daily missing a precious opportunity for early exposure to the world's technology.

Through the Sambaza ICT4Tommorow program, in collaboration with an international body of researchers in ICT development and education,Ogembo believes working with primary schools in East Africa and global private and public institutions looking to make a difference in the lives of young people, to donate computers, money, and effort towards the goal of both providing primary schools with technology and training, but also to provide East African's communities and individuals with the necessary first exposure to ICT so that they might be able to master future technology.

This project's primary goal is to work with the schools and the local community leaders first, to ensure that East Africa receives the technology and training that it really needs. By combining empassioned researchers with civic-minded institutions Sambaza hope to create change in East Africa far beyond the addition of computers in classrooms.

Extra activities

Ogembo is much interested also in interdisciplinary research, and that has seen him partners with his academic peers at Nagoya University to start an international interdisciplinary research colloquium known as FeedForth."'

FeedForth

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FeedForth (FF) is an international conference organized by Nagoya University graduate students, created to explore opportunities for academic dialogue among researchers operating in diverse fields. It is the goal of FeedForth to address the following questions: - What can we gain if we are aware of the work of our colleagues in different disciplines? - What can we learn if we step back from the intricacies of our particular subject and see "the big picture"?

- How can our own work be improved by considering the commonality between researchers' problems, approaches, and solutions?

- How might new, rewarding academic relationships be forged?

FF was created both as an opportunity for exchange, and specifically as an answer to problems that we perceived in other conferences involving their approach to the discussion among attendees and guests.FF is an attempt to carefully create our image of an ideal conference. To that end, the FF conference operates under the following tenets: - A lively environment for constructive criticism;

- Emphasis on discussion and audience interaction;

- Equality among all- the free sharing of ideas among all participants in an equal forum

External links

* [http://www.sambazagroup.com Sambaza Group]
*http://www.feedforth.org/FeedForth07/Feedforth.html
*http://www.agr.nagoya-u.ac.jp/english/e2senko1-tx.html
*http://www.icipe.org/
*http://www.wits.ac.za/
*http://www.nagoya-u.ac.jp/en/
*http://sciencelinks.jp/j-east/article/200707/000020070707A0232034.php
*http://www.agr.nagoya-u.ac.jp/~baculo/
*http://www.ecis.nagoya-u.ac.jp/about/pub-pdf/Newsletter/No20.pdf
*http://www.warwick.ac.uk/fac/sci/whri/about/staff/dwinstanley/