Biomedical subjects

Wayne B Hunter

Publications and source records attributed to Wayne B Hunter.

8 recordsLinked to original sources

PubMed2006

Phylogenetic and structural relationships of the PR5 gene family reveal an ancient multigene family conserved in plants and select animal taxa.

Pathogenesis-related group 5 (PR5) plant proteins include thaumatin, osmotin, and related proteins, many of which have antimicrobial activity. The recent discovery of PR5-like (PR5-L) sequences in nematodes and insects raises questions about their evolutionary relationships. Using complete plant genome data and discovery of multiple insect PR5-L sequences, phylogenetic comparisons among plants and animals were performed. All PR5/PR5-L protein sequences were mined from genome data of a member of each of two main angiosperm groups-the eudicots (Arabidoposis thaliana) and the monocots (Oryza sativa)-and from the Caenorhabditis nematode (C. elegans and C. briggsase). Insect PR5-L sequences were mined from EST databases and GenBank submissions from four insect orders: Coleoptera (Diaprepes abbreviatus and Biphyllus lunatus), Orthoptera (Schistocerca gregaria), Hymenoptera (Lysiphlebus testaceipes), and Hemiptera (Toxoptera citricida). Parsimony and Bayesian phylogenetic analyses showed that the PR5 family is paraphyletic in plants, likely arising from 10 genes in a common ancestor to monocots and eudicots. After evolutionary divergence of monocots and eudicots, PR5 genes increased asymmetrically among the 10 clades. Insects and nematodes contain multiple sequences (seven PR5-Ls in nematodes and at least three in some insects) all related to the same plant clade, with nematode and insect sequences separating as two clades. Protein structural homology modeling showed strong similarity among animal and plant PR5/PR5-Ls, with divergence only in surface-exposed loops. Sequence and structural conservation among PR5/PR5-Ls suggests an important and conserved role throughout the evolutionary divergence of the diverse organisms from which they reside.

Amino Acid Sequence↗

PubMed2006

Genome sequence and molecular characterization of Homalodisca coagulata virus-1, a novel virus discovered in the glassy-winged sharpshooter (Hemiptera: Cicadellidae).

The complete nucleotide sequence of a novel single-stranded RNA virus infecting the glassy-winged sharpshooter, Homalodisca coagulata, has been determined. In silico analysis of H. coagulata virus-1 (HoCV-1) revealed a 9321-nt polyadenylated genome encoding two large open reading frames (ORF1 and ORF2) separated by a 182-nt intergenic region (IGR). The deduced amino acid sequence of the 5'-proximal ORF (ORF1, nt 420-5807) exhibited conserved core motifs characteristic of the helicases, cysteine proteases, and RNA-dependent RNA polymerases of other insect-infecting picorna-like viruses. A structural model created using Mfold exposed a series of stem loop (SL) structures immediately preceding the second ORF which are analogous to an internal ribosome entry site (IRES), suggesting that ORF2 begins with a noncognate GCA triplet rather than the canonical AUG. This 3' ORF2 (5990-8740) showed significant similarity to the structural proteins of members of the family Dicistroviridae, particularly those belonging to the genus Cripavirus. Evidence demonstrating relatedness of these viruses regarding genome organization, amino acid sequence similarity, and putative replication strategy substantiate inclusion of HoCV-1 into this taxonomic position.

Amino Acid Sequence↗

PubMed2006

A dual-genome microarray for the pea aphid, Acyrthosiphon pisum, and its obligate bacterial symbiont, Buchnera aphidicola.

BACKGROUND: The best studied insect-symbiont system is that of aphids and their primary bacterial endosymbiont Buchnera aphidicola. Buchnera inhabits specialized host cells called bacteriocytes, provides nutrients to the aphid and has co-speciated with its aphid hosts for the past 150 million years. We have used a single microarray to examine gene expression in the pea aphid, Acyrthosiphon pisum, and its resident Buchnera. Very little is known of gene expression in aphids, few studies have examined gene expression in Buchnera, and no study has examined simultaneously the expression profiles of a host and its symbiont. Expression profiling of aphids, in studies such as this, will be critical for assigning newly discovered A. pisum genes to functional roles. In particular, because aphids possess many genes that are absent from Drosophila and other holometabolous insect taxa, aphid genome annotation efforts cannot rely entirely on homology to the best-studied insect systems. Development of this dual-genome array represents a first attempt to characterize gene expression in this emerging model system. RESULTS: We chose to examine heat shock response because it has been well characterized both in Buchnera and in other insect species. Our results from the Buchnera of A. pisum show responses for the same gene set as an earlier study of heat shock response in Buchnera for the host aphid Schizaphis graminum. Additionally, analyses of aphid transcripts showed the expected response for homologs of known heat shock genes as well as responses for several genes with unknown functional roles. CONCLUSION: We examined gene expression under heat shock of an insect and its bacterial symbiont in a single assay using a dual-genome microarray. Further, our results indicate that microarrays are a useful tool for inferring functional roles of genes in A. pisum and other insects and suggest that the pea aphid genome may contain many gene paralogs that are differentially regulated.

Animals↗

PubMed2005

Differential transcriptional activity of plant-pathogenic begomoviruses in their whitefly vector (Bemisia tabaci, Gennadius: Hemiptera Aleyrodidae).

Plant-pathogenic begomoviruses have a complex association with their whitefly vector and aspects concerning virus genetic activity (genome replication and gene transcription) within the insect remain highly controversial. Virus transcript abundance was assessed by quantifying selected gene transcripts of Tomato mottle virus (ToMoV, a New World bipartite begomovirus) and Tomato yellow leaf curl virus (TYLCV, an Old World monopartite begomovirus) in whiteflies (Bemisia tabaci biotype B) after feeding on virus-infected tomato plants and after subsequent transfer to cotton, a plant that is immune to the selected begomoviruses. Real-time RT-PCR was performed using specific primers for three ToMoV genes (AV1, BC1 and BV1) and three TYLCV genes (V1, V2 and C3). The ToMoV gene transcripts rapidly became undetectable in whiteflies following transfer from tomato to cotton, probably because degradation was not accompanied by new synthesis. On the other hand, TYLCV transcripts increased after transfer of whiteflies to cotton, indicating active TYLCV transcription. Interestingly, the difference observed in ToMoV and TYLCV transcripts in the vector parallel observations on the different biological effects of these viruses on whiteflies, i.e. TYLCV, but not ToMoV, reduces whitefly fitness.

Animals↗

PubMed2004

A picorna-like virus from the red imported fire ant, Solenopsis invicta: initial discovery, genome sequence, and characterization.

We report the first discovery and genome sequence of a virus infecting the red imported fire ant, Solenopsis invicta. The 8026 nucleotide, polyadenylated, RNA genome encoded two large open reading frames (ORF1 and ORF2), flanked and separated by 27, 223, and 171 nucleotide untranslated regions, respectively. The predicted amino acid sequence of the 5' proximal ORF1 (nucleotides 28 to 4218) exhibited significant identity and possessed consensus sequences characteristic of the helicase, cysteine protease, and RNA-dependent RNA polymerase sequence motifs from picornaviruses, picorna-like viruses, comoviruses, caliciviruses, and sequiviruses. The predicted amino acid sequence of the 3' proximal ORF2 (nucleotides 4390-7803) showed similarity to structural proteins in picorna-like viruses, especially the acute bee paralysis virus. Electron microscopic examination of negatively stained samples from virus-infected fire ants revealed isometric particles with a diameter of 31 nm, consistent with Picornaviridae. A survey for the fire ant virus from areas around Florida revealed a pattern of fairly widespread distribution. Among 168 nests surveyed, 22.9% were infected. The virus was found to infect all fire ant caste members and developmental stages, including eggs, early (1st-2nd) and late (3rd-4th) instars, worker pupae, workers, sexual pupae, alates ( male symbol and female symbol ), and queens. The virus, tentatively named S. invicta virus (SINV-1), appears to belong to the picorna-like viruses. We did not observe any perceptible symptoms among infected nests in the field. However, in every case where an SINV-1-infected colony was excavated from the field with an inseminated queen and held in the laboratory, all of the brood in these colonies died within 3 months.

3' Untranslated Regions↗

PubMed2004

Putative protease inhibitor gene discovery and transcript profiling during fruit development and leaf damage in grapefruit (Citrus paradisi Macf.).

Seven putative protease inhibitor (PPI) cDNAs, representing four protein families, were isolated from a grapefruit (Citrus paradisi Macf. Cv. Marsh) immature fruit flavedo cDNA library. Cloned open reading frames encoded proteins with similarity to, and protein signatures for: legume Kuntiz inhibitors (lkiL-1, lkiL-2, lkiL-3), potato trypsin inhibitor I (ptiIL-1), serpins (serpL-1), cystatins (cystL-1), and gamma thionins (gthL-1). Response of transcript abundance to fruit development and leaf wounding was determined for all but lkiL-1 using real-time RT-PCR. Immature leaves had the highest transcript levels for all PPIs. The gthL-1 transcript in immature leaves was the most abundant transcript but was absent from healthy mature leaves. In fruit flavedo, transcripts for all PPIs were most abundant in youngest fruit (<15 mm dia. fruit), and declined during development, but displayed different patterns of developmental change. Mechanical or Diaprepes root weevil (DRW) feeding damage to leaves caused a <10-fold reduction or had no effect on transcript level with the exception of gthL-1 which, as a result of damage, increased >50-fold in mature leaves and decreased >1400-fold in immature leaves. This developmental control of transcript response to wounding in a woody perennial is opposite of what has been observed for defensive proteinase inhibitors (PIs) in other plants (typically herbaceous and/or annual plants), where younger leaves typically invoke a higher defensive proteinase inhibitor transcript accumulation than older tissues. Except for gthL-1, the PPI transcripts were minimally responsive or unresponsive to wounding. Changes in PPI transcript levels suggest diverse roles for the products of these genes in citrus, with only gthL-1 responding in a defense-like manner.

Citrus↗

PubMed2004

Sucrose octanoate toxicity to brown citrus aphid (Homoptera: Aphididae) and the parasitoid Lysiphlebus testaceipes (Hymenoptera: Aphidiidae).

We report the toxicological effects of a new biorational, synthetic sucrose octanoate (AVA Chemical Ventures L.L.C., Portsmouth, NH), on brown citrus aphid, Toxoptera citricida (Kirkaldy), nymphs and adults and to its native parasitoid Lysiphlebus testaceipes (Cresson). Sucrose octanoate topically applied was equally toxic to brown citrus aphid adults and nymphs with LC50 and LC90 values ranging from 356 to 514 and 1029 to 1420 ppm, respectively. Mortalities of both stages did not differ significantly over time during the 3-24-h sampling period. Dry residues of sucrose octanoate exhibited similar levels of toxicity to both nymphs and adults. Mortality ranged from 60 to 70% at 6,000 ppm 4 h after exposure. L. testaceipes was not harmed by treatments as high as 4,000 ppm of sucrose octanoate as long as the parasitoid had mummified before treatment. Based on these results, sucrose octanoate would be a useful biorational in citrus integrated pest management programs.

Animals↗

PubMed2003

Toxicity and repellency of Tephrosia candida to larval and adult Diaprepes root weevil (Coleoptera: Curculionidae).

Leaves of the tropical legume Tephrosia candida DC deterred feeding by adults of the Diaprepes root weevil, Diaprepes abbreviatus (L.), compared with leaves of Citrus macrophylla Wester, a common citrus rootstock, or T. vogelii Hook. f. When larvae were placed in pots containing plants of the three species for 28 d in a growth chamber, larval survival and weight gain were significantly reduced in pots containing plants of T. candida compared with larvae in pots with C. macrophylla or T. vogelii. Diet incorporation of lyophilized roots of T. candida into an artificial diet increasingly inhibited the growth of larvae and increased larval mortality with increased concentration of roots, whereas roots from C. macrophylla or T. vogelii had no effect compared with the diet-only control. T. candida, but not T. vogelii, contains at least one constituent that acts as an antifeedant toward adult D. abbreviatus and as a toxicant toward larvae. No antifeedant effect of roots of T. candida toward larvae was observed in no-choice pot tests or in a diet incorporation bioassay. In pots, larval feeding damage to roots of T. candida was evident. In the diet incorporation assay, 97% of larvae survived 29 d on a diet of cellulose powder (a nutritionally inert filler) despite losing weight. We conclude that decreased survival and weight gain of larvae-fed fresh or lyophilized roots of T. candida were the result of ingestion of a toxicant and not deterrence from feeding.

Animals↗