J. Spencer Johnston
A5005658482- Insect and Arachnid Ecology and Behavior
- Insect and Pesticide Research
- Plant and animal studies
- Insect symbiosis and bacterial influences
- Insect-Plant Interactions and Control
- Insect Resistance and Genetics
- Genetic diversity and population structure
- Chromosomal and Genetic Variations
- Mosquito-borne diseases and control
- Hemiptera Insect Studies
- Genomics and Phylogenetic Studies
- Insect behavior and control techniques
- Phytoplasmas and Hemiptera pathogens
- Forest Insect Ecology and Management
- Evolution and Genetic Dynamics
- Plant Virus Research Studies
- Vector-borne infectious diseases
- Plant Disease Resistance and Genetics
- Research on scale insects
- Insect Utilization and Effects
- Fossil Insects in Amber
- Forensic Entomology and Diptera Studies
- Yersinia bacterium, plague, ectoparasites research
- Lepidoptera: Biology and Taxonomy
- Entomopathogenic Microorganisms in Pest Control
Texas A&M University
2016-2025
Mitchell Institute
2001-2024
European Bioinformatics Institute
2007
Wellcome Trust
2007
Broad Institute
2007
Virginia Tech
2007
Johns Hopkins University
2007
University of Illinois Urbana-Champaign
2006
Cornell University
2006
Texas College
2004
We present a draft sequence of the genome Aedes aegypti, primary vector for yellow fever and dengue fever, which at approximately 1376 million base pairs is about 5 times size malaria Anopheles gambiae. Nearly 50% Ae. aegypti consists transposable elements. These contribute to factor 4 6 increase in average gene length sizes intergenic regions relative An. gambiae Drosophila melanogaster. Nonetheless, chromosomal synteny generally maintained among all three insects, although conservation...
The Drosophila melanogaster Genetic Reference Panel (DGRP) is a community resource of 205 sequenced inbred lines, derived to improve our understanding the effects naturally occurring genetic variation on molecular and organismal phenotypes. We used an integrated genotyping strategy identify 4,853,802 single nucleotide polymorphisms (SNPs) 1,296,080 non-SNP variants. Our population genomic analyses show higher deletion than insertion mutation rates stronger purifying selection deletions....
As an obligatory parasite of humans, the body louse (Pediculus humanus humanus) is important vector for human diseases, including epidemic typhus, relapsing fever, and trench fever. Here, we present genome sequences its primary bacterial endosymbiont Candidatus Riesia pediculicola. The has smallest known insect genome, spanning 108 Mb. Despite status as obligate parasite, it retains a remarkably complete basal repertoire 10,773 protein-coding genes 57 microRNAs. Representing hemimetabolous...
Female Aedes aegypti mosquitoes infect more than 400 million people each year with dangerous viral pathogens including dengue, yellow fever, Zika and chikungunya. Progress in understanding the biology of developing tools to fight them has been slowed by lack a high-quality genome assembly. Here we combine diverse technologies produce markedly improved, fully re-annotated AaegL5 assembly, demonstrate how it accelerates mosquito science. We anchored physical cytogenetic maps, doubled number...
Stick to the Bush Can underlying genetic changes driving divergence of populations into new species be predicted or repeated? Soria-Carrasco et al. (p. 738 ) investigated observed after one generation when stick insect ( Timema cristinae were transplanted from their preferred host plants alternative hosts. Diverged regions relatively small, with most loci showing in a single population pair. However, number parallel was greater than expected by chance. Thus, selection can drive phenotypic...
We characterized Apis mellifera in both native and introduced ranges using 1136 single-nucleotide polymorphisms genotyped 341 individuals. Our results indicate that A. originated Africa expanded into Eurasia at least twice, resulting populations eastern western Europe are geographically close but genetically distant. A third expansion the New World has involved near-replacement of previously "European" honey bees by descendants more recently m. scutellata ("African" or "killer" bees)....
For bees, many roads lead to social harmony Eusociality, where workers sacrifice their reproductive rights support the colony, has evolved repeatedly and represents most form of evolution in insects. Kapheim et al. looked across genomes 10 bee species with varying degrees sociality determine underlying genomic contributions. No one path led eusociality, but similarities were seen features such as increases gene regulation methylation. It also seems that selection pressures relaxed after...
Restriction-site associated DNA (RAD) sequencing is a powerful new method for targeted across the genomes of many individuals. This approach has broad potential genetic analysis non-model organisms including genotype-phenotype association mapping, phylogeography, population genetics and scaffolding genome assemblies through linkage mapping. We constructed RAD library using genomic from Plutella xylostella (diamondback moth) backcross that segregated resistance to insecticide spinosad....
Relatively little is known about the genomic basis and evolution of wood-feeding in beetles. We undertook genome sequencing annotation, gene expression assays, studies plant cell wall degrading enzymes, other functional comparative Asian longhorned beetle, Anoplophora glabripennis, a globally significant invasive species capable inflicting severe feeding damage on many important tree species. Complementary genes encoding enzymes involved digestion woody tissues or detoxification...
Abstract The bed bug, Cimex lectularius , has re-established itself as a ubiquitous human ectoparasite throughout much of the world during past two decades. This global resurgence is likely linked to increased international travel and commerce in addition widespread insecticide resistance. Analyses C. sequenced genome (650 Mb) 14,220 predicted protein-coding genes provide comprehensive representation that are traumatic insemination, reduced chemosensory repertoire related obligate...
Eukaryotic genome sizes range over five orders of magnitude. This variation cannot be explained by differences in organismic complexity (the C value paradox). To test the hypothesis that some size can attributed to patterns insertion and deletion (indel) mutations among organisms, this study examines indel spectrum Laupala crickets, which have a 11 times larger than Drosophila . Consistent with hypothesis, DNA loss is more 40 slower
Abstract As an accompanying manuscript to the release of honey bee genome, we report entire sequence nuclear (18S, 5.8S, 28S and 5S) mitochondrial (12S 16S) ribosomal RNA (rRNA)‐encoding gene sequences (rDNA) related internally externally transcribed spacer regions Apis mellifera (Insecta: Hymenoptera: Apocrita). Additionally, predict secondary structures for mature rRNA molecules based on comparative analyses with other arthropod taxa reference recently published crystal ribosome. In...
Flow cytometry was used to compare 14 potential reference standards for plant DNA content determination. Both chicken and internal were used, as propidium iodide (PI) 4'‐6‐diamidino‐2‐phenylindole (DAPI) fluorochromes. Means standard errors of the means are presented standards, compared those obtained by Feulgen densitometry. Five species recommended an initial set international future determinations: Sorghum bicolor cv. Pioneer 8695 (2C = 1.74 pg), Pisum sativum Minerva Maple 9.56 Hordeum...
Nuclear 1C DNA content in haploid megagametophyte tissue of 18 North American and one exotic Pinus species was determined using scanning microspectrophotometry. The nuclear root meristematic cells Zea mays L. ssp. , inbred line Va35 (4C = 10.31 pg) used as a standard. measured by microspectrophotometry verified laser flow cytometry with two additional standards, Hordeum vulgare cv. Sultan (2C 11.12 P. eldarica 47.30 pg). values obtained both methods were significantly correlated (r 0.987)....
An improved procedure is reported for determining DNA amounts of plant nuclei. Nuclei stained with propidium iodide, isolated from chopped leaves, were passed through an Ortho Cytofluorograph a Lexel model 95 argon laser (514 nm) and the fluorescence measured, integrated, recorded using 2140 Data Acquisition computer. All nuclear samples mixed nuclei Sultan barley (2C content = 11.12 pg [picogram]) as internal standard. contents ten species, ranging 2C 1.7 to 36.1 measured by flow cytometry,...
The midge, Belgica antarctica, is the only insect endemic to Antarctica, and thus it offers a powerful model for probing responses extreme temperatures, freeze tolerance, dehydration, osmotic stress, ultraviolet radiation other forms of environmental stress. Here we present first genome assembly an extremophile, dipteran in family Chironomidae, Antarctic eukaryote be sequenced. At 99 megabases, B. antarctica has smallest sequenced far. Although similar number genes as Diptera, midge very low...
Abstract Background The ectoparasitic mite Varroa destructor has emerged as the primary pest of domestic honey bees ( Apis mellifera ). Here we present an initial survey V. genome carried out to advance our understanding biology and identify new avenues for control. This sequence provides immediate resources molecular population-genetic analyses - interactions defines challenges ahead a comprehensive project. Results size was estimated by flow cytometry be 565 Mbp, larger than most sequenced...
SummarySummaryThe recognition that the Dark European honey bee, Apis mellifera mellifera, is increasingly threatened in its native range has led to establishment of conservation programmes and protected areas throughout western Europe. Previous molecular surveys showed that, despite management strategies preserve genetic integrity A. m. populations had a measurable component their gene pool derived from commercial C-lineage bees. Here we used both sequence data tRNAleu-cox2 intergenic mtDNA...
Abstract Background The Hemiptera (aphids, cicadas, and true bugs) are a key insect order, with high diversity for feeding ecology excellent experimental tractability molecular genetics. Building upon recent sequencing of hemipteran pests such as phloem-feeding aphids blood-feeding bed bugs, we present the genome sequence comparative analyses centered on milkweed bug Oncopeltus fasciatus , seed feeder family Lygaeidae. Results 926-Mb is well represented by current assembly official gene set....
Measuring genome size across different species can yield important insights into evolution of the and allow for more informed decisions when designing next-generation genomic sequencing projects. New techniques estimating using shallow sequence data have emerged which potential to augment our knowledge sizes, yet these methods only been used in a limited number empirical studies. In this project, we compare estimation (k-mer average read depth single-copy genes) measurements from flow...
Abstract Background The Asian tiger mosquito Aedes albopictus is globally expanding and has become the main vector for human arboviruses in Europe. With limited antiviral drugs vaccines available, control primary approach to prevent mosquito-borne diseases. A reliable accurate DNA sequence of Ae. genome essential develop new approaches that involve genetic manipulation mosquitoes. Results We use long-read sequencing methods modern scaffolding techniques (PacBio, 10X, Hi-C) produce AalbF2, a...
Hyalella azteca is a cryptic species complex of epibenthic amphipods interest to ecotoxicology and evolutionary biology. It the primary crustacean used in North America for sediment toxicity testing an emerging model molecular ecotoxicology. To provide resources quality assessments studies, we sequenced, assembled, annotated genome H. U.S. Lab Strain. The completeness comparable with other ecotoxicological species. Through targeted investigation use gene expression data sets exposed...