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J. Spencer Johnston

J. Spencer Johnston


Department of Entomology

2475 TAMU
College Station , TX 77843-2475
Office Phone: (979) 845-8295


  1. B.S., Zoology, University of Washington, 1967
  2. Ph.D., Genetics, University of Arizona, 1972
  3. Postdoc., Genetics, University of Texas, 1975


Research Interests:

Genomics: Our honey bee genomic efforts use SNPs to identify markers for Varroa and virus resistance in the honey bee, We are also contribute to development of arthropod whole genome sequencing projects and annote genes as part of those projects.  Recent efforts include the body louse and aphid projects and a proposed whole genome sequencing of Caencholax fenyesi (Strepsitpera:Myrmecolacidae), an insect parasitic in the red imported fireant, and one of the smallest known insect genomes.

Population level studies:  We have been assessing the genetic impact of the arrival of the Africanized form of the honey bee, Apis mellifera scutellata. We have extensive collections of feral bees from colonies in South Texas and bait hive bees in Mexico spanning the period 1990 to 2003, which is three years prior, the time during, and the successive years after the invasion of the Africanized bee. We score mtDNA mitotypes and microsatellite loci and SNPs. The data shows that the African and European mitochondrial lineages coexist, while the nuclear genome is a mixture of the genomes of both lineages. Mexican populations and European colonies in Texas that survived the Africanization process are being studied further.

Genome size estimation: Our laboratory uses flow cytometry to provide the scientific community with accurate genome size estimates for a wide variety of arthropods, nematodes, plants and other animals. We measure genome size in order to correct questionable values produced by other methods, and provide new values for researches who need to know genome size to develop genomics projects. In an ongoing effort we determine genome size in groups of closely related organisms in an effort to better understand the process of genome size evolution.

Selected Publications:

Schmidt-Ott, U., Rafiqi, A.M., Sander, K., and Johnston, J.S. 2009. Extremely small genomes in two unrelated dipteran insects with shared early developmental traits. Dev Genes Evol 219: 207-210.

Azizi, T., Johnston, J.S., and Vinson, S.B. 2009. Initiation of flight muscle apoptosis and wing casting in the red imported fire ant Solenopsis invicta. Physiological Entomology 34: 79-85.

Tsutsui, N.D., Suarez, A.V., Spagna, J.C., and Johnston, J.S. 2008. The evolution of genome size in ants. BMC Evol Biol 8: 64.

Gregory, T.R. and Johnston, J.S. 2008. Genome size diversity in the family Drosophilidae. Heredity 101: 228-238.

Bennett, M.D., Price, H.J., and Johnston, J.S. 2008. Anthocyanin inhibits propidium iodide DNA fluorescence in Euphorbia pulcherrima: implications for genome size variation and flow cytometry. Ann Bot 101: 777-790.

Barcenas, N.M., Thompson, N.J., Gomez-Tovar, V., Morales-Ramos, F.A., and Johnston, J.S. 2008. Sex Determination and Genome Size in Catolaccus grandis (Burks, 1954) (Hymenoptera: Pteromalidae). Journal of Hymenoptera Research 17: 201-209.

Abubucker, S., Martin, J., Yin, Y., Fulton, L., Yang, S.P., Hallsworth-Pepin, K., Johnston, J.S., Hawdon, J., McCarter, J.P., Wilson, R.K. et al. 2008. The canine hookworm genome: Analysis and classification of Ancylostoma caninum survey sequences. Molecular and Biochemical Parasitology 157: 187-192.

Pinto, M.A., Sheppard, W.S., Johnston, J.S., Rubink, W.L., Coulson, R.N., Schiff, N.M., Kandemir, I., and Patton, J.C. 2007. Honey bees (Hymenoptera : Apidae) of African origin exist in non-Africanized areas of the Southern United States: Evidence from mitochondrial DNA. Annals of the Entomological Society of America 100: 289-295.

Nene, V., Wortman, J.R., Lawson, D., Haas, B., Kodira, C., Tu, Z.J., Loftus, B., Xi, Z.Y., Megy, K., Grabherr, M. et al. 2007. Genome sequence of Aedes aegypti, a major arbovirus vector. Science 316: 1718-1723.

Kathirithamby, J., Gillespie, J.J., Jimenez-Guri, E., Cognato, A.I., and Johnston, J.S. 2007. High nucleotide divergence in a dimorphic parasite with disparate hosts. Zootaxa: 59-68.

Johnston, J.S., Yoon, K.S., Strycharz, J.P., Pittendrigh, B.R., and Clark, J.M. 2007. Body lice and head lice (Anoplura: Pediculidae) have the smallest genomes of any hemimetabolous insect reported to date. J Med Entomol 44: 1009-1012.

Geraci, N.S., Johnston, J.S., Robinson, J.P., Wikel, S.K., and Hill, C.A. 2007. Variation in genome size of argasid and ixodid ticks. Insect Biochemistry and Molecular Biology 37: 399-408.

Azizi, T., Johnston, J.S., and Vinson, S.B. 2007. A gene involved in postmating flight muscle degeneration in red imported fire ant (Hymenoptera : Formicidae) queens. Annals of the Entomological Society of America 100: 270-274.

Whitfield, C.W., Behura, S.K., Berlocher, S.H., Clark, A.G., Johnston, J.S., Sheppard, W.S., Smith, D.R., Suarez, A.V., Weaver, D., and Tsutsui, N.D. 2006. Thrice out of Africa: Ancient and recent expansions of the honey bee, Apis mellifera. Science 314: 642-645.

Weinstock, G.M. Robinson, G.E. Gibbs, R.A. Worley, K.C. Evans, J.D. Maleszka, R. Robertson, H.M. Weaver, D.B. Beye, M. Bork, P. et al. 2006. Insights into social insects from the genome of the honeybee Apis mellifera. Nature 443: 931-949.

Pittendrigh, B.R., Clark, J.M., Johnston, J.S., Lee, S.H., Romero-Severson, J., and Dasch, G.A. 2006. Sequencing of a new target genome: the Pediculus humanus humanus (Phthiraptera: Pediculidae) genome project. J Med Entomol 43: 1103-1111.

Gillespie, J.J., Johnston, J.S., Cannone, J.J., and Gutell, R.R. 2006. Characteristics of the nuclear (18S, 5.8S, 28S and 5S) and mitochondrial (12S and 16S) rRNA genes of Apis mellifera (Insecta: Hymenoptera): structure, organization, and retrotransposable elements. Insect Mol Biol 15: 657-686.

Price, H.J., Dillon, S.L., Hodnett, G., Rooney, W.L., Ross, L., and Johnston, J.S. 2005. Genome evolution in the genus Sorghum (Poaceae). Ann Bot 95: 219-227.

Pinto, M.A., Rubink, W.L., Patton, J.C., Coulson, R.N., and Johnston, J.S. 2005. Africanization in the United States: replacement of feral European honeybees (Apis mellifera L.) by an African hybrid swarm. Genetics 170: 1653-1665.

Johnston, J.S., Pepper, A.E., Hall, A.E., Chen, Z.J., Hodnett, G., Drabek, J., Lopez, R., and Price, H.J. 2005. Evolution of genome size in Brassicaceae. Ann Bot 95: 229-235.

Jiggins, C.D., Mavarez, J., Beltran, M., McMillan, W.O., Johnston, J.S., and Bermingham, E. 2005. A genetic linkage map of the mimetic butterfly Heliconius melpomene. Genetics 171: 557-570.

Gillespie, J.J., McKenna, C.H., Yoder, M.J., Gutell, R.R., Johnston, J.S., Kathirithamby, J., and Cognato, A.I. 2005. Assessing the odd secondary structural properties of nuclear small subunit ribosomal RNA sequences (18S) of the twisted-wing parasites (Insecta: Strepsiptera). Insect Mol Biol 14: 625-643.

DeSalle, R., Gregory, T.R., and Johnston, J.S. 2005. Preparation of samples for comparative studies of arthropod chromosomes: Visualization, in situ hybridization, and genome size estimation. Molecular Evolution: Producing the Biochemical Data, Part B 395: 460-488.

Coulson, R.N., Pinto, M.A., Tchakerian, M.D., Baum, K.A., Rubink, W.L., and Johnston, J.S. 2005. Feral honey bees in pine forest landscapes of east Texas. Forest Ecology and Management 215: 91-102.

Ren, S.X., Johnston, J.S., Shippen, D.E., and McKnight, T.D. 2004. TELOMERASE ACTIVATOR1 induces telomerase activity and potentiates responses to auxin in Arabidopsis. Plant Cell 16: 2910-2922.

Pinto, M.A., Rubink, W.L., Coulson, R.N., Patton, J.C., and Johnston, J.S. 2004. Temporal pattern of africanization in a feral honeybee population from Texas inferred from mitochondrial DNA. Evolution 58: 1047-1055.

Kathirithamby, J. and Johnston, J.S. 2004. The discovery after 94 years of the elusive female of a myrmecolacid (Strepsiptera), and the cryptic species of Caenocholax fenyesi Pierce sensu lato. Proc Biol Sci 271 Suppl 3: S5-8.

Johnston, J.S., Ross, L.D., Beani, L., Hughes, D.P., and Kathirithamby, J. 2004. Tiny genomes and endoreduplication in Strepsiptera. Insect Molecular Biology 13: 581-585.

Dillon, S.L., Lawrence, P.K., Henry, R.J., Ross, L., Price, H.J., and Johnston, J.S. 2004. Sorghum laxiflorum and S-macrospermum, the Australian native species most closely related to the cultivated S-bicolor based on ITS1 and ndhF sequence analysis of 25 Sorghum species. Plant Systematics and Evolution 249: 233-246.

Pinto, M.A., Johnston, J.S., Rubink, W.L., Coulson, R.N., Patton, J.C., and Sheppard, W.S. 2003. Identification of Africanized honey bee (Hymenoptera : Apidae) mitochondrial DNA: Validation of a rapid polymerase chain reaction-based assay. Annals of the Entomological Society of America 96: 679-684.

Kathirithamby, J., Ross, L.D., and Johnston, J.S. 2003. Masquerading as self? Endoparasitic strepsiptera (Insecta) enclose themselves in host-derived epidermal bag. Proceedings of the National Academy of Sciences of the United States of America 100: 7655-7659.

Bennett, M.D., Leitch, I.J., Price, H.J., and Johnston, J.S. 2003. Comparisons with Caenorhabditis (similar to 100 Mb) and Drosophila (similar to 175 Mb) using flow cytometry show genome size in Arabidopsis to be similar to 157 Mb and thus similar to 25 % larger than the Arabidopsis genome initiative estimate of similar to 125 Mb. Annals of Botany 91: 547-557.

Wendel, J.F., Cronn, R.C., Johnston, J.S., and Price, H.J. 2002. Feast and famine in plant genomes. Genetica 115: 37-47.

Grauke, L.J., Price, H.J., and Johnston, J.S. 2001. Genome size of pecan as determined by flow cytometry. Hortscience 36: 814-814.

Auckland, L.D., Johnston, J.S., Price, H.J., and Bridgwater, F.E. 2001. Stability of nuclear DNA content among divergent and isolated populations of Fraser fir. Canadian Journal of Botany-Revue Canadienne De Botanique 79: 1375-1378.

Petrov, D.A., Sangster, T.A., Johnston, J.S., Hartl, D.L., and Shaw, K.L. 2000. Evidence for DNA loss as a determinant of genome size. Science 287: 1060-1062.

Research Interests:

Bioinformatics and Genomics:

genome size evolution, provide genome size estimates for complete genome sequencing projects, & utilize  population genomics to improve honey bee health

Conservation and Population Genetics:

genome size evolution, provide genome size estimates for complete genome sequencing projects, & utilize  population genomics to improve honey bee health


GENE 412 Population and Ecological Genetics
GENE 481 Genetics I Seminar
GENE 482 Genetics II Seminar