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Igor V Sharakhov, PhD

Title Assistant Professor Phone (540) 231-7316 Fax (540) 231-9131 E-Mail igor@vt.edu Address 203 Fralin Biotechnology Center West Campus Drive, MC 0390 Virginia Tech Blacksburg, VA 24061 Web Additional Web Site

Welcome to the Sharakhov Lab!

The lab members in 2009 from left to right: Fan Yang (MS student), Krisha Witt (undergraduate student), Phillip George (PhD student), Maryam Kamali (PhD student), Maria Sharakhova (Research Scientist), Alexandra Tammariello (undergraduate student), Igor Sharakhov (PI), Ai Xia (PhD candidate).

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Evolutionary Genomics and Cytogenetics of Disease Vectors

The research in my lab focuses on comparative genomics and molecular genetics of the malaria mosquitoes. Ecological, behavioral, and physiological adaptations related to malaria transmission are often associated with rearrangements (such as chromosomal inversions) in the mosquito genome. We are interested in understanding the mechanism of how chromosomal inversions originate, evolve, and affect the ability of a mosquito to transmit malaria parasites and to adapt to diverse environments. Understanding the biological effects of genome rearrangements can have a great impact on public health through a higher efficiency of control measures of vector borne infectious diseases. For example, genes affected by inversion polymorphism can be used as new targets for modulating vectorial capacity to our advantage.

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Dr. Sharakhov's publications (selected from 27 peer-reviewed research articles)

1. Xia, A., M. V. Sharakhova, and I. V. Sharakhov. 2008. Reconstructing ancestral autosomal arrangements in the Anopheles gambiae complex. Journal of Computational Biology, 15(8):1-16.
2. Scali, C., T. Nolan, I. V. Sharakhov, M. V. Sharakhova, A. Crisanti, and F. Catteruccia. 2007. Post-integration behavior of a Minos transposon in the malaria mosquito Anopheles stephensi. Mol Genet Genomics,  278(5):575-584.
3. Riehle, M. M., K. Markianos, L. Lambrechts, A. Xia., I. V. Sharakhov, J. C. Koella, and K. D. Vernick. 2007. A major genetic locus controlling natural Plasmodium falciparum infection is shared by East and West African Anopheles gambiae. Malaria J 6:87.
4. White, B. J., F. Santolamazza, L. Kamau, M. Pombi, O. Grushko, K. Mouline, C. Brengues, W. Guelbeogo, M. Coulibaly, J. K. Kayondo, I. V. Sharakhov, F. Simard, V. Petrarca, A. Della Torre, and N. J. Besansky. 2007. Molecular karyotyping of the 2La inversion in Anopheles gambiae. Am J Trop Med Hyg 76: 334-9.
5. Sharakhova, M. V., A. Xia, S. I. McAlister, and I. V. Sharakhov. 2006. A standard cytogenetic photomap for the mosquito Anopheles stephensi (Diptera: Culicidae): application for physical mapping. J Med Entomol 43: 861-6.
6. Sharakhov, I. V., B. J. White, M. V. Sharakhova, J. Kayondo, N. F. Lobo, F. Santolamazza, A. Della Torre, F. Simard, F. H. Collins, and N. J. Besansky. 2006. Breakpoint structure reveals the unique origin of an interspecific chromosomal inversion (2La) in the Anopheles gambiae complex. Proc Natl Acad Sci U S A 103: 6258-62.
7. Sharakhov, I. V., O. Braginets, O. Grushko, A. Cohuet, W. M. Guelbeogo, D. Boccolini, M. Weill, C. Costantini, N. Sagnon, D. Fontenille, G. Yan, and N. J. Besansky. 2004. A microsatellite map of the African human malaria vector Anopheles funestus. J Hered 95: 29-34.
8. Pai, A., I. V. Sharakhov, O. Braginets, C. Costa, and G. Yan. 2003. Identification of microsatellite markers in the red flour beetle, Tribolium castaneum. Molecular Ecology Notes 3: 425-427.
9. Sharakhov, I. V., A. C. Serazin, O. G. Grushko, A. Dana, N. Lobo, M. E. Hillenmeyer, R. Westerman, J. Romero-Severson, C. Costantini, N. Sagnon, F. H. Collins, and N. J. Besansky. 2002. Inversions and gene order shuffling in Anopheles gambiae and A. funestus. Science 298: 182-5.
10. Sharakhov, I. V., O. Braginets, C. N. Mbogo, and G. Yan. 2001. Isolation and characterization of trinucleotide microsatellites in African malaria mosquito Anopheles funestus. Molecular Ecology Notes 1: 289-292.
11. Sharakhov, I. V., M. V. Sharakhova, C. M. Mbogo, L. L. Koekemoer, and G. Yan. 2001. Linear and spatial organization of polytene chromosomes of the African malaria mosquito Anopheles funestus. Genetics 159: 211-8.

Former lab members:

Omotara Ogundeyi, Undergraduate student, 2007-2008. .

Lauren White, Undergraduate student, 2006-2007. .

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Sarah McAllister, Undergraduate student, 2005-2006.

Links

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Blurb last modified at 2009-02-25 10:10:08.0.

Professional Memberships

• American Society for Tropical Medicine and Hygiene
• Genetics Society of America

Personnel

• Faculty
  • Sharakhova, Maria
• Student
  • George, Phillip
  • Kamali, Maryam
  • Xia, Ai
  • Yang, Fan

Projects

• Chromosomal phylogeny of the Anopheles gambiae complex
  Morphologically indistinguishable members of the Anopheles gambiae complex have remarkably distinct ecological adaptations, geographical distributions, and behaviors. Development of novel approaches to malaria management implies finding the ways to interrupt transmission by replacing populations of vectors with nonvectors. Our current knowledge about differences in genetic make-up among vectors and nonvectors is insufficient for implementing the successful population replacement. Inferring ancestral genomic features in the A. gambiae complex is crucial in identifying the evolutionary changes associated with the origin and loss of human blood choice, ecological and behavioral adaptations, and association with human habitats. These genomic changes should be targeted and manipulated so that malaria transmission can be reduced and eventually eliminated.
  
  
• Comparative Genomics of the 2La Inversion Breakpoints in Anopheles gambiae
  Malaria, with its great biological and social complexity, remains one of the most important global health problems today. One novel approach for controlling infectious diseases is targeting genes responsible for vector competence. The genome of the most efficient malaria vector, Anopheles gambiae, has a number of chromosomal polymorphisms linked to specific adaptations related to malaria transmission. The 2La polymorphic inversion is widespread across natural populations of A. gambiae and associated with at least two epidemiologically important phenotypes: decreased Plasmodium falciparum infection rates and adaptation to arid climate. We propose a model where the alternative chromosomal arrangements of the 2La inversion affect vector competence and adaptation to aridity by capturing and stabilizing different haplotypic variants containing allelic complexes of specific genes. Our ability to control these “effector genes” would lead to interference with parasite development and, as a result, to elimination of malaria transmission. The long-term goal of this research is to understand the mechanism of association between inversion polymorphism and the epidemiologically important phenotypes in order to develop novel tools for inhibiting parasite transmission.
  
  
• Ecological Adaptations of Malaria Mosquitoes
  The mosquito’s ability to adapt ecologically can significantly increase malaria transmission because it allows mosquitoes to occupy larger geographic regions and even human dwellings.
  
  
• Population Cytogenetics of Anopheles moucheti and Anopheles nili
  Malaria has a devastating impact on public health and welfare in the African continent. An important approach for reducing or eliminating malaria impact is vector control. However, vector control is inefficient if not all major vector species are targeted. Mosquitoes of subgenus Cellia—Anopheles gambiae, An. arabiensis, An. funestus, An. moucheti, and An. nili—are the major malaria vectors because they are antropophilic and susceptible to Plasmodium falciparum. An. gambiae, An. arabiensis, and An. funestus are being intensively studied with the help of cytogenetic and molecular markers. An. moucheti and An. nili have received significantly less attention because the tools needed to precisely characterize species diversity and population structure are lacking. This project offers a unique opportunity to develop cytogenetic research tools and to assess their effectiveness for taxonomic and population genetics studies of the neglected malaria vectors An. moucheti and An. nili.
  
  
• Resistance management for the tobacco-adapted form of the green peach aphid on tobacco
  Studies are underway to establish baseline information on the toxicity of imidacloprid and acephate and to assess biochemical and genetic differences between tolerant and susceptible colonies of the tobacco-feeding form of the green peach aphid, Myzus persicae. We are evaluating colonies of two color morphs (red and green) of the aphid from farms located across the flue-cured and burley tobacco-producing regions of Virginia and eight other tobacco-producing states. So far, there have been moderate differences in toxicity (based on LC50 values) to imidacloprid (Admire) between the most susceptible and least susceptible colonies. Color morph appears to have no effect on resistance to imidacloprid. These tests are being continued to compare levels of tolerance among clones and to establish baselines that can be used to monitor for aphid resistance in the future.
  
  

Courses

• ENT 5324 Genomics of Disease Vectors
  An in-depth examination of the modern approaches and techniques currently employed to study genomes of arthropod vectors of human, animal, and plant diseases. Topics include: genome organization, regulation, and evolution; preparation and analysis of chromosomes; genome mapping, sequencing and assembly; principles of taxonomy and systematics; adaptation and evolution of arthropod vectors; genetics of vector competence; comparative genomics and bioinformatics. Upon completion of the course, students will be able to: 1. Describe structural and functional organization of genomes of disease vectors. 2. Describe the state-of-the-art methods for obtaining and analyzing genomic data. 3. Explain the high levels of gene regulation and genomic changes in development and evolution of vectors. 4. Determine taxonomic position of selected vectors using genomic and cytogenetic data. 5. Utilize genome databases and bioinformatics tools for comparative genomics of arthropod vectors.
  
  

Resources

• Fralin Insectary
  The Fralin Insectaries are located in Rooms 320A, 320A1 and 319 in the Fralin Biotechnology Center. These facilities are shared between researchers in the Departments of Entomology and Biochemistry, and support the CALS and University focus on Vector-Borne Infectious Disease research.
  
  

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