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PubMed2002

Towards a molecular understanding of Drosophila hearing.

The Drosophila auditory system is presented as a powerful new genetic model system for understanding the molecular aspects of development and physiology of hearing organs. The fly's ear resides in the antenna, with Johnston's organ serving as the mechanoreceptor. New approaches using electrophysiology and laser vibrometry have provided useful tools to apply to the study of mutations that disrupt hearing. The fundamental developmental processes that generate the peripheral nervous system are fairly well understood, although specific variations of these processes for chordotonal organs (CHO) and especially for Johnston's organ require more scrutiny. In contrast, even the fundamental physiologic workings of mechanosensitive systems are still poorly understood, but rapid recent progress is beginning to shed light. The identification and analysis of mutations that affect auditory function are summarized here, and prospects for the role of the Drosophila auditory system in understanding both insect and vertebrate hearing are discussed.

Animals↗
PubMed1993

Isolation, characterization and sequence of a cDNA encoding gamma-tubulin protein from the fern Anemia phyllitidis L. Sw.

A complete cDNA encoding gamma-tubulin protein from Anemia phyllitidis is presented. The deduced amino acid sequence shows an average similarity of 81-86% to known gamma-tubulin genes from insects, mammals and fungi. Northern blots indicate the existence of transcripts of ca. 1.9 kb which are expressed during gametogenesis of A. phyllitidis. The gene described is the first cloned and entirely sequenced gamma-tubulin gene in any plant.

Amino Acid Sequence↗
PubMedDate not supplied

Evolutionary discontinuity of the Carabine ground beetles.

The Carabine ground beetles are mostly hind wing-less and cannot fly, so that there is more chance of diversification by geographic isolation compared with winged insects. The relationships between morphological diversification and phylogeny of the ground beetles of the world have been inferred mainly by comparisons of mitochondrial ND5 gene sequences. Based on dating by a mitochondrial DNA "clock," it has been deduced that an explosive radiation of the major carabine groups took place 50-40 MYA. This was followed by occasional radiations on various scales, sometimes accompanied by parallel morphological changes. There are also a good number of examples showing that the fundamental morphology has remained unchanged for a long time among geographically isolated populations within the same species. Thus, carabid evolution would have proceeded discontinuously, with phases of rapid morphological change alternating with silent phases.

Animals↗
PubMed2004

Identification of four genes expressed by feeding female Ixodes scapularis, including three with sequence similarity to previously recognized genes.

We created a cDNA library from feeding, female Ixodes scapularis ticks and screened the library with a subtracted probe to eliminate most genes common to feeding female and mating male I. scapularis ticks. Four unique genes were identified in this screen. One gene, Is 9, (represented by 16 cDNAs) was more highly expressed in female ticks. This gene encodes a putative glycine-rich protein, which matched a number of glycine-rich proteins including attachment cement proteins from Rhipicephalus appendiculatus. A second gene, Is 10 (represented by one cDNA) was also more highly expressed in female ticks, but did not match any other sequences in the GenBank database. The third gene, Is 11 (represented by one cDNA) was very similar to Drosophila sp. hsp68 and hsp70 genes and was expressed about equally in male and female ticks. The fourth gene, Is 12 (represented by two cDNAs) was also about equally expressed in male and female ticks, and was similar to a salivary gland gene from Ixodes ricinis. This gene also showed limited similarity to some cuticle genes from insects.

Amino Acid Sequence↗
PubMed2006

Insect odor and taste receptors.

Insect odor and taste receptors are highly sensitive detectors of food, mates, and oviposition sites. Following the identification of the first insect odor and taste receptors in Drosophila melanogaster, these receptors were identified in a number of other insects, including the malaria vector mosquito Anopheles gambiae; the silk moth, Bombyx mori; and the tobacco budworm, Heliothis virescens. The chemical specificities of many of the D. melanogaster receptors, as well as a few of the A. gambiae and B. mori receptors, have now been determined either by analysis of deletion mutants or by ectopic expression in in vivo or heterologous expression systems. Here we discuss recent advances in our understanding of the molecular and cellular basis of odor and taste coding in insects.

Animals↗
PubMed2006

Genome and EST analyses and expression of a gene family with putative functions in insect chemoreception.

Odorant-binding proteins (OBPs) are thought to be responsible for the transport of semiochemicals across hydrophobic interfaces to olfactory receptors. In insects, a second class of OBPs with four conserved cysteines has been variously named as sensory appendage proteins, olfactory segment-D proteins, and chemosensory proteins (CSPs). The physiological functions of these proteins have remained elusive. Here we report a comprehensive survey of both genome and expressed sequence tags (EST) databases. This showed that CSPs are apparently only present in the phylum, Arthropoda, and in two subphyla, Crustacea and Uniramia. This is the first report of a putative CSP in Crustacea and suggests that the origin of these genes predates the divergence of Uniramia and Crustacea. For the Uniramia, we identified 74 new genes encoding putative CSPs of insect species from 10 different orders. Using tissue-specific EST libraries, we have examined the relative expression of putative CSP genes in many tissues from 22 insect species suggesting that the genes are expressed widely. One Drosophila CSPs is expressed sixfold higher in head than other CSPs. One Bombyx mori CSPs was found at a very high level in pheromone gland, and for the first time, six CSPs were identified in B. mori compound eyes. The different frequencies of CSP transcripts were observed between solitary and gregarious EST libraries of Locusta migratoria.

Animals↗
PubMed2000

Wolbachia neither induces nor suppresses transcripts encoding antimicrobial peptides.

Wolbachia are intracellular maternally inherited microorganisms that are associated with reproductive abnormalities such as cytoplasmic incompatibility (CI), feminization and parthenogenesis in the various arthropod species they infect. Surveys indicate that these bacteria infect more than 16% of all insect species as well as isopods, mites and nematodes, making Wolbachia one of the most ubiquitous parasites yet described. However, nothing is known about the interactions of this bacterium with the host's immune system. We studied the expression of inducible antimicrobial markers in the adults of two Wolbachia infected insect species, Drosophila simulans and Aedes albopictus. The lack of available immune markers in the mosquito species led us to clone part of the defensin gene from this species, which was found to be very similar to the other mosquito defensins cloned from Anopheles gambiae and Aedes aegypti. Comparisons of the expression pattern of the antibacterial markers between Wolbachia-infected and cured lines, and also between bacteria-challenged and unchallenged adults indicated that Wolbachia does not either constitutively induce or suppress the transcription of these antibacterial genes. In addition, no difference in the transcription of these genes was found between double and single Wolbachia-infected strains or between strains in which Wolbachia has different tissue tropisms.

Aedes↗
PubMed2022

Expansive and Diverse Phenotypic Landscape of Field Aedes aegypti (Diptera: Culicidae) Larvae with Differential Susceptibility to Temephos: Beyond Metabolic Detoxification.

Arboviruses including dengue, Zika, and chikungunya are amongst the most significant public health concerns worldwide. Arbovirus control relies on the use of insecticides to control the vector mosquito Aedes aegypti (Linnaeus), the success of which is threatened by widespread insecticide resistance. The work presented here profiled the gene expression of Ae. aegypti larvae from field populations of Ae. aegypti with differential susceptibility to temephos originating from two Colombian urban locations, Bello and Cúcuta, previously reported to have distinctive disease incidence, socioeconomics, and climate. We demonstrated that an exclusive field-to-lab (Ae. aegypti strain New Orleans) comparison generates an over estimation of differential gene expression (DGE) and that the inclusion of a geographically relevant field control yields a more discrete, and likely, more specific set of genes. The composition of the obtained DGE profiles is varied, with commonly reported resistance associated genes including detoxifying enzymes having only a small representation. We identify cuticle biosynthesis, ion exchange homeostasis, an extensive number of long noncoding RNAs, and chromatin modelling among the differentially expressed genes in field resistant Ae. aegypti larvae. It was also shown that temephos resistant larvae undertake further gene expression responses when temporarily exposed to temephos. The results from the sampling triangulation approach here contribute a discrete DGE profiling with reduced noise that permitted the observation of a greater gene diversity, increasing the number of potential targets for the control of insecticide resistant mosquitoes and widening our knowledge base on the complex phenotypic network of the Ae. aegypti response to insecticides.

Aedes↗
PubMed2005

Olfactory memory formation in Drosophila: from molecular to systems neuroscience.

The olfactory nervous system of insects and mammals exhibits many similarities, which suggests that the mechanisms for olfactory learning may be shared. Molecular genetic investigations of Drosophila learning have uncovered numerous genes whose gene products are essential for olfactory memory formation. Recent studies of the products of these genes have continued to expand the range of molecular processes known to underlie memory formation. Recent research has also broadened the neuroanatomical areas thought to mediate olfactory learning to include the antennal lobes in addition to a previously accepted and central role for the mushroom bodies. The roles for neurons extrinsic to the mushroom body neurons are becoming better defined. Finally, the genes identified to participate in Drosophila olfactory learning have conserved roles in mammalian organisms, highlighting the value of Drosophila for gene discovery.

Animals↗
PubMed2001

Dynamic nuclear localization of the baculovirus proteins IE2 and PE38 during the infection cycle: the promyelocytic leukemia protein colocalizes with IE2.

The early gene products IE2 and PE38 of Autographa californica multicapsid nuclear polyhedrosis virus localize to distinct nuclear domains after transient expression. Here, the nuclear localization pattern and the putative association with cellular proteins have been determined during virus infection to shed light on the functional significance of the nuclear domains. IE2 was always localized to distinct nuclear structures while PE38 was partly present in nuclear dots. Confocal imaging indicated colocalization of PE38 and IE2 to common domains, prominently at 2 h p.i. The nuclear dot localization of PE38 in infected cells was different from that in transfected cells. Hence, we have performed cotransfection experiments that suggested that a viral factor influences the nuclear distribution. Since the promyelocytic leukemia protein (PML) that localizes to distinct nuclear multiprotein complexes termed ND10/PODs in mammalian cells functions as a target for some immediate early viral proteins, we have investigated whether baculovirus proteins act similarly. Transiently expressed IE2 and PE38 were found to be associated with endogenous PML in the mammalian cell line BHK21. Infection with a recombinant virus that expresses the human pml gene in insect cells reveals IE2 and PML to be colocalized during the early phase of infection followed by a redistribution of both proteins. Taken together our results provide first evidence that the early baculovirus protein IE2 associates at least with one component of mammalian PODs during virus infection, suggesting that POD-like structures can be formed in insect cells.

Animals↗
PubMed1999

Regeneration in insects.

@9cIntroduction@21T issues exhibit an impressive ability to respond to a myriad of insults by repairing and regenerating complex structures. The elegant and orderly process of regeneration provides clues to the mechanisms of pattern formation but also offers the hope that the process might one day be manipulated to replace damaged body parts. To manipulate the process, it will be necessary to understand the genetic basis of the process. In the case of the insect leg, we are coming close to such a level of understanding and many of the lessons learned are relevant to vertebrate systems. A dynamic web of gene regulatory networks appears to create a robust self-organizing system that is at once extremely intricate but also perhaps simple in its reliance on a few key signaling pathways and a few simple processes, e.g. autoactivation and lateral inhibition. Here we will summarize what has been learned about the networks of gene regulation present in the Drosophila leg discs and then we will explore how the regenerative responses to different insults can be understood as predictable responses to these networks. Each of the regulatory networks could themselves serve as the subject of a detailed review and that is beyond the scope of this discussion. Here we will focus on the interplay between the regulatory networks in patterning the tissue.

Animals↗
PubMed2006

Beepath: an ordered quantitative-PCR array for exploring honey bee immunity and disease.

Honey bees and other insects face many important parasites and pathogens against which they have evolved behavioral, morphological, physiological, and immune-based defenses. To help validate honey bee immune-gene candidates and determine their responsiveness to pathogens, a quantitative-PCR array was developed to measure transcript levels for 48 honey bee and pathogen genes in parallel. It is shown that this array can accurately measure host and pathogen transcript abundance, providing a new tool for assessing the environmental and genetic components behind honey bee immunity. By using common platforms and chemistries (e.g., SYBR-Green intercalating dye), quantitative-PCR arrays such as the one described should have diverse uses in invertebrate pathology.

Animals↗
PubMed2004

Linkage mapping of powdery mildew and greenbug resistance genes on recombinant 1RS from 'Amigo' and 'Kavkaz' wheat-rye translocations of chromosome 1RS.1AL.

Cultivated rye (Secale cereale L., 2n = 2x = 14, RR) is an important source of genes for insect and disease resistance in wheat (Triticum aestivum L., 2n = 6x = 42). Rye chromosome arm 1RS of S. cereale 'Kavkaz' originally found as a 1BL.1RS translocation, carries genes for disease resistance (e.g., Lr26, Sr31, Yr9, and Pm8), while 1RS of the S. cereale 'Amigo' translocation (1RSA) carries a single resistance gene for greenbug (Schizaphis graminum Rondani) biotypes B and C and also carries additional disease-resistance genes. The purpose of this research was to identify individual plants that were recombinant in the homologous region of.1AL.1RSV and 1AL.1RSA using both molecular and phenotypic markers. Secale cereale 'Nekota' (1AL.1RSA) and S. cereale 'Pavon 76' (1AL.1RSV) were mated and the F1 was backcrossed to 'Nekota' (1AL.1AS) to generate eighty BC1F2:3 families (i.e., ('Nekota' 1AL.1RSA x 'Pavon 76' 1AL.1RSV) x 'Nekota' 1AL.1AS). These families were genotyped using the secalin-gliadin grain storage protein banding pattern generated with polyacrylamide gel electrophoresis to discriminate 1AL.1AS/1AL.1RS heterozygotes from the 1AL.1RSA+V and 1AL.1AS homozygotes. Segregation of the secalin locus and PCR markers based on the R173 family of rye specific repeated DNA sequences demonstrated the presence of recombinant 1AL.1RSA+V families. Powdery mildew (Blumeria graminis) and greenbug resistance genes on the recombinant 1RSA+V arm were mapped in relation to the Sec-1 locus, 2 additional protein bands, 3 SSRs, and 13 RFLP markers. The resultant linkage map of 1RS spanned 82.4 cM with marker order and spacing showing reasonable agreement with previous maps of 1RS. Fifteen markers lie within a region of 29.7 cM next to the centromere, yet corresponded to just 36% of the overall map length. The map position of the RFLP marker probe mwg68 was 10.9 cM distal to the Sec-1 locus and 7.8 cM proximal to the powdery mildew resistance locus. The greenbug resistance gene was located 2.7 cM proximal to the Sec-1 locus.

Animals↗
PubMed2000

Baculovirus-mediated gene transfer into pancreatic islet cells.

Baculovirus transduction is a gene transfer method that uses a moth cell virus for mammalian cells in culture, which results in a high-level prolonged expression. Here we demonstrate that recombinant baculoviruses can serve as efficient gene transfer vehicles for delivering foreign genes driven by mammalian promoters into human and mouse pancreatic islet cells. Existing methods, such as various transfection and electroporation techniques, either suffer from low efficiency or cause extensive membrane damage. Viral vectors have emerged as an important tool for gene delivery and expression in mammalian cells but suffer from several drawbacks, such as lengthy construction time and expression of viral genes. The baculovirus Autographa californica multiple nuclear polyhedrosis virus is widely used as a vector for expression of foreign genes in insect cells and, more recently, in some mammalian cells. Using several green fluorescent protein- and LacZ-expressing constructs in a cytomegalovirus promoter cassette, we obtained efficient gene expression in primary human and mouse islet cells. There was no impairment of glucose-stimulated intracellular free calcium responses after baculovirus infection. The safety and the relative ease of construction and propagation of the virus makes the baculovirus system a useful tool for facilitating the transfer of foreign genes.

Animals↗
PubMed2000

Nuclear genes resolve mesozoic-aged divergences in the insect order Lepidoptera.

Compared to the number of genes available for study of both younger and older divergences, few genes have yet been identified that can strongly resolve phylogenetic splits of Mesozoic age ( approximately 65-250 mya). Thus, reconstruction of Mesozoic-age phylogenies, exemplified by basal divergences within the major orders of holometabolous insects, is likely to be especially dependent on combining multiple lines of evidence. This study tests the potential of the 18S ribosomal RNA gene for reconstructing Mesozoic-aged divergences within the insect order Lepidoptera and its ability when combined with a second, previously analyzed nuclear gene (phosphoenolpyruvate carboxykinase, PEPCK) to strongly resolve these relationships. 18S sequences were obtained for 21 taxa, representing major clades of Lepidoptera plus outgroups from the other "panorpoid orders. A well-corroborated morphology-based "test phylogeny was used to evaluate the effects of partitioning the 18S gene according to variable versus conserved domains, paired versus unpaired sites in the secondary structure, and transition versus transversion substitutions. Likelihood and unweighted parsimony analyses of the 18S data recover the "test phylogeny" almost completely, with no improvement of agreement or support provided by any form of weighting or partitioning. No conflict in signal between 18S and PEPCK was detected by the partition homogeneity test. Combined parsimony analysis yielded strong bootstrap support for nearly all relationships, much higher than for either gene alone, thereby also providing strong evidence on several hypotheses about the early evolution of lepidopteran-plant interactions. These genes in combination may be widely useful for resolving insect divergences of comparable age.

Animals↗
PubMed1995

Polymorphic SINEs in chironomids with DNA derived from the R2 insertion site.

A short interspersed repeat (SINE) in the two sibling species Chironomus pallidivittatus and Chironomus tentans is described. It is present at many sites in the genome and is surrounded by 10 to 14 bp target site duplications. It consists of two sequence modules in different numbers and variable order relative to each other and often has large inversions of different sizes at one end. One of the modules contains pol III promoter consensus sequences. This SINE, nevertheless, is likely to have been dependent on an outside promoter for its formation. It is therefore interesting that both modules start with a 22 bp region with striking similarity to the R2 insertion site in the preribosomal gene of insects. We suggest that this type of SINE, termed Cp1, was formed after a series of events among which the first step was the retroposition of a tRNA gene into the R2 site in the preribosomal gene by the R2 coded protein. The final step is likely to have been due to retroposition from this site.

Animals↗