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On the Base Composition of Transposable Elements. Int J Mol Sci 2022; 23:ijms23094755. [PMID: 35563146 PMCID: PMC9099904 DOI: 10.3390/ijms23094755] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 04/22/2022] [Accepted: 04/23/2022] [Indexed: 01/27/2023] Open
Abstract
Transposable elements exhibit a base composition that is often different from the genomic average and from hosts’ genes. The most common compositional bias is towards Adenosine and Thymine, although this bias is not universal, and elements with drastically different base composition can coexist within the same genome. The AT-richness of transposable elements is apparently maladaptive because it results in poor transcription and sub-optimal translation of proteins encoded by the elements. The cause(s) of this unusual base composition remain unclear and have yet to be investigated. Here, I review what is known about the nucleotide content of transposable elements and how this content can affect the genome of their host as well as their own replication. The compositional bias of transposable elements could result from several non-exclusive processes including horizontal transfer, mutational bias, and selection. It appears that mutation alone cannot explain the high AT-content of transposons and that selection plays a major role in the evolution of the compositional bias. The reason why selection would favor a maladaptive nucleotide content remains however unexplained and is an area of investigation that clearly deserves attention.
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Meredith JM, Underhill A, McArthur CC, Eggleston P. Next-generation site-directed transgenesis in the malaria vector mosquito Anopheles gambiae: self-docking strains expressing germline-specific phiC31 integrase. PLoS One 2013; 8:e59264. [PMID: 23516619 PMCID: PMC3596282 DOI: 10.1371/journal.pone.0059264] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 02/13/2013] [Indexed: 01/27/2023] Open
Abstract
Diseases transmitted by mosquitoes have a devastating impact on global health and the situation is complicated due to difficulties with both existing control measures and the impact of climate change. Genetically modified mosquitoes that are refractory to disease transmission are seen as having great potential in the delivery of novel control strategies. The Streptomyces phage phiC31 integrase system has been successfully adapted for site-directed transgene integration in a range of insects, thus overcoming many limitations due to size constraints and random integration associated with transposon-mediated transformation. Using this technology, we previously published the first site-directed transformation of Anopheles gambiae, the principal vector of human malaria. Mosquitoes were initially engineered to incorporate the phiC31 docking site at a defined genomic location. A second phase of genetic modification then achieved site-directed integration of an anti-malarial effector gene. In the current publication we report improved efficiency and utility of the phiC31 integrase system following the generation of Anopheles gambiae self-docking strains. Four independent strains, with docking sites at known locations on three different chromosome arms, were engineered to express integrase under control of the regulatory regions of the nanos gene from Anopheles gambiae. The resulting protein accumulates in the posterior oocyte to provide integrase activity at the site of germline development. Two self-docking strains, exhibiting significantly different levels of integrase expression, were assessed for site-directed transgene integration and found to demonstrate greatly improved survival and efficiency of transformation. In the fight against malaria, it is imperative to establish a broad repertoire of both anti-malarial effector genes and tissue-specific promoters to regulate their expression, enabling those offering maximum effect with minimum fitness cost to be identified. The improved technology we describe here will facilitate comparative studies of effector transgenes, allowing informed choices to be made that potentially lead to transmission blockade.
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Affiliation(s)
- Janet M. Meredith
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Ann Underhill
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Clare C. McArthur
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
| | - Paul Eggleston
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire, United Kingdom
- * E-mail:
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Abstract
The whole-genome sequencing of mosquitoes has facilitated our understanding of fundamental biological processes at their basic molecular levels and holds potential for application to mosquito control and prevention of mosquito-borne disease transmission. Draft genome sequences are available for Anopheles gambiae, Aedes aegypti, and Culex quinquefasciatus. Collectively, these represent the major vectors of African malaria, dengue fever and yellow fever viruses, and lymphatic filariasis, respectively. Rapid advances in genome technologies have revealed detailed information on genome architecture as well as phenotype-specific transcriptomics and proteomics. These resources allow for detailed comparative analyses within and across populations as well as species. Next-generation sequencing technologies will likely promote a proliferation of genome sequences for additional mosquito species as well as for individual insects. Here we review the current status of genome research in mosquitoes and identify potential areas for further investigations.
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Affiliation(s)
- David W Severson
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556, USA.
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Behura SK, Severson DW. Coadaptation of isoacceptor tRNA genes and codon usage bias for translation efficiency in Aedes aegypti and Anopheles gambiae. INSECT MOLECULAR BIOLOGY 2011; 20:177-87. [PMID: 21040044 PMCID: PMC3057532 DOI: 10.1111/j.1365-2583.2010.01055.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The transfer RNAs (tRNAs) are essential components of translational machinery. We determined that tRNA isoacceptors (tRNAs with different anticodons but incorporating the same amino acid in protein synthesis) show differential copy number abundance, genomic distribution patterns and sequence evolution between Aedes aegypti and Anopheles gambiae mosquitoes. The tRNA-Ala genes are present in unusually high copy number in the Ae. aegypti genome but not in An. gambiae. Many of the tRNA-Ala genes of Ae. aegypti are flanked by a highly conserved sequence that is not observed in An. gambiae. The relative abundance of tRNA isoacceptor genes is correlated with preferred (or optimal) and nonpreferred (or rare) codons for ∼2-4% of the predicted protein coding genes in both species. The majority (∼74-85%) of these genes are related to pathways involved with translation, energy metabolism and carbohydrate metabolism. Our results suggest that these genes and the related pathways may be under translational selection in these mosquitoes.
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Affiliation(s)
| | - David W. Severson
- Correspondence: David W. Severson, Phone: 574-631-3826, FAX: 574-631-7413,
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Rispe C, Legeai F, Gauthier JP, Tagu D. Strong heterogeneity in nucleotidic composition and codon bias in the pea aphid (Acyrthosiphon pisum) shown by EST-based coding genome reconstruction. J Mol Evol 2007; 65:413-24. [PMID: 17928936 DOI: 10.1007/s00239-007-9023-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2006] [Revised: 06/08/2007] [Accepted: 07/02/2007] [Indexed: 10/22/2022]
Abstract
The aim of this study was to analyze patterns of nucleotidic composition and codon usage in the pea aphid genome (Acyrthosiphon pisum). A collection of 60,000 expressed sequence tags (ESTs) in the pea aphid has been used to automatically reconstruct 5809 coding sequences (CDSs), based on similarity with known proteins and on coding style recognition. Reconstructions were manually checked for ribosomal proteins, leading to tentatively reconstruct the nea-complete set of this category. Pea aphid coding sequences showed a shift toward AT (especially at the third codon position) compared to drosophila homologues. Genes with a putative high level of expression (ribosomal and other genes with high EST support) remained more GC3-rich and had a distinct codon usage from bulk sequences: they exhibited a preference for C-ending codons and CGT (for arginine), which thus appeared optimal for translation. However, the discrimination was not as strong as in drosophila, suggesting a reduced degree of translational selection. The space of variation in codon usage for A. pisum appeared to be larger than in drosophila, with a substantial fraction of genes that remained GC3-rich. Some of those (in particular some structural proteins) also showed high levels of codon bias and a very strong preference for C-ending codons, which could be explained either by strong translational selection or by other mechanisms. Finally, genomic traces were analyzed to build 206 fragments containing a full CDS, which allowed studying the correlations between GC contents of coding and those of noncoding (flanking and introns) sequences.
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Affiliation(s)
- Claude Rispe
- Institut National de la Recherche Agronomique, Domaine de la Motte, Unité Mixte de Recherche 1099 BIO3P, Le Rheu, France.
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6
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Sabater-Muñoz B, Legeai F, Rispe C, Bonhomme J, Dearden P, Dossat C, Duclert A, Gauthier JP, Ducray DG, Hunter W, Dang P, Kambhampati S, Martinez-Torres D, Cortes T, Moya A, Nakabachi A, Philippe C, Prunier-Leterme N, Rahbé Y, Simon JC, Stern DL, Wincker P, Tagu D. Large-scale gene discovery in the pea aphid Acyrthosiphon pisum (Hemiptera). Genome Biol 2006; 7:R21. [PMID: 16542494 PMCID: PMC1557754 DOI: 10.1186/gb-2006-7-3-r21] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2005] [Revised: 01/23/2006] [Accepted: 02/16/2006] [Indexed: 11/30/2022] Open
Abstract
Aphids are the leading pests in agricultural crops. A large-scale sequencing of 40,904 ESTs from the pea aphid Acyrthosiphon pisum was carried out to define a catalog of 12,082 unique transcripts. A strong AT bias was found, indicating a compositional shift between Drosophila melanogaster and A. pisum. An in silico profiling analysis characterized 135 transcripts specific to pea-aphid tissues (relating to bacteriocytes and parthenogenetic embryos). This project is the first to address the genetics of the Hemiptera and of a hemimetabolous insect.
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Affiliation(s)
- Beatriz Sabater-Muñoz
- INRA Rennes, UMR INRA-Agrocampus BiO3P, BP 35327, F-35653 Le Rheu Cedex, France
- Current address: Instituto Valenciano de Investigaciones Agrarias (IVIA), Proteccion Vegetal y Biotecnologia, Lab Entomologia, 46113 Moncada, Valencia, Spain
| | - Fabrice Legeai
- INRA, URGI - Genoplante Info, Infobiogen, 523 place des Terrasses, F-91000 Evry, France
| | - Claude Rispe
- INRA Rennes, UMR INRA-Agrocampus BiO3P, BP 35327, F-35653 Le Rheu Cedex, France
| | - Joël Bonhomme
- INRA Rennes, UMR INRA-Agrocampus BiO3P, BP 35327, F-35653 Le Rheu Cedex, France
| | - Peter Dearden
- Biochemistry Department, University of Otago, PO Box 56, Dunedin, New Zealand
| | - Carole Dossat
- GENOSCOPE and CNRS UMR 8030, Centre National de Séquençage, 2 rue Gaston Crémieux, F-91000 Evry Cedex, France
| | - Aymeric Duclert
- INRA, URGI - Genoplante Info, Infobiogen, 523 place des Terrasses, F-91000 Evry, France
| | | | | | - Wayne Hunter
- USDA, Agricultural Research Service, US Horticultural Research Laboratory, 2001 South Rock Road, Fort Pierce, FL 34945, USA
| | - Phat Dang
- USDA, Agricultural Research Service, US Horticultural Research Laboratory, 2001 South Rock Road, Fort Pierce, FL 34945, USA
| | - Srini Kambhampati
- Department of Entomology, Kansas State University, Manhattan, KS 66506, USA
| | - David Martinez-Torres
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva (ICBIBE), Universitat de Valencia, Apartado de Correos 2085, 46071 Valencia, Spain
| | - Teresa Cortes
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva (ICBIBE), Universitat de Valencia, Apartado de Correos 2085, 46071 Valencia, Spain
| | - Andrès Moya
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva (ICBIBE), Universitat de Valencia, Apartado de Correos 2085, 46071 Valencia, Spain
| | - Atsushi Nakabachi
- Environmental Molecular Biology Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan
| | - Cathy Philippe
- INRA, URGI - Genoplante Info, Infobiogen, 523 place des Terrasses, F-91000 Evry, France
| | | | - Yvan Rahbé
- INRA Lyon, UMR INRA-INSA BF2I, INSA Bâtiment Louis-Pasteur, 20 avenue A. Einstein, 69621 Villeurbanne cedex, France
| | | | - David L Stern
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA
| | - Patrick Wincker
- GENOSCOPE and CNRS UMR 8030, Centre National de Séquençage, 2 rue Gaston Crémieux, F-91000 Evry Cedex, France
| | - Denis Tagu
- INRA Rennes, UMR INRA-Agrocampus BiO3P, BP 35327, F-35653 Le Rheu Cedex, France
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Montero-Solis C, Gonzalez-Ceron L, Rodriguez MH, Cirerol BE, Zamudio F, Possanni LD, James AA, de la Cruz Hernandez-Hernandez F. Identification and characterization of gp65, a salivary-gland-specific molecule expressed in the malaria vector Anopheles albimanus. INSECT MOLECULAR BIOLOGY 2004; 13:155-164. [PMID: 15056363 DOI: 10.1111/j.0962-1075.2004.00473.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A group of salivary-gland-specific proteins, designated gp65, were identified in the mosquito Anopheles albimanus. Two-dimensional gel electrophoresis resolved this group into at least four molecules with pI 6.4-6.5. The N-terminal amino acid sequence was determined for the major species, gp65-1, and degenerate oligonucleotide primers were used to amplify a specific probe for library screening. A 1312 bp cDNA clone encoding a predicted translation product of 386 amino acids was recovered. gp65-1 is expressed abundantly in the medial and distal-lateral lobes of the adult female glands, and is secreted in the saliva. The amino acid sequence has potential sites for N-glycosylation, phosphorylation and myristylation, and is similar to a number of proteins of unknown function from other mosquito species.
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Affiliation(s)
- C Montero-Solis
- Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, México D.F., México
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8
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Morlais I, Severson DW. Intraspecific DNA variation in nuclear genes of the mosquito Aedes aegypti. INSECT MOLECULAR BIOLOGY 2003; 12:631-639. [PMID: 14986924 DOI: 10.1046/j.1365-2583.2003.00449.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Single nucleotide polymorphisms (SNPs) are an abundant source of genetic variation among individual organisms. To assess the usefulness of SNPs for genome analysis in the yellow fever mosquito, Aedes aegypti, we sequenced 25 nuclear genes in each of three strains and analysed nucleotide diversity. The average frequency of nucleotide variation was 12 SNPs per kilobase, indicating that nucleotide variation in Ae. aegypti is similar to that in other organisms, including Drosophila and the malaria vector Anopheles gambiae. Transition polymorphisms outnumbered transversion polymorphisms, at a ratio of about 2:1. We examined codon usage and confirmed that mutational bias favours G and C ending codons. Codon bias was most pronounced in highly expressed genes. Nucleotide diversity estimates indicated that substitution rates are positively correlated in coding and non-coding regions. Nucleotide diversity varied from one gene to another. The unequal distribution of SNPs among Ae. aegypti nuclear genes suggests that single base variations are non-neutral and are subject to selective constraints. Our analysis showed that ubiquitously expressed genes have lower polymorphism rates and are likely under strong purifying selection, whereas tissue specific genes and genes with a putative role in parasite defence exhibit higher levels of polymorphism that may be associated with diversifying selection.
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Affiliation(s)
- I Morlais
- Center for Tropical Disease Research and Training, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
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9
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DeSalle R, Branham MA, O'Grady P, Gatesy J. The evolution of HOM-C homeoboxes in the Dipteran family Drosophilidae. INSECT MOLECULAR BIOLOGY 2003; 12:345-351. [PMID: 12864914 DOI: 10.1046/j.1365-2583.2003.00417.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Forty-five new Homeotic Complex (HOM-C) homeobox sequences from six species of Drosophilidae (Drosophila heteroneura, D. adiastola, Zaprionus vittiger, Chymomyza amoena, Scaptodrosophila pattersoni and Hirtodrosophila pictiventris) were obtained using a PCR-cloning method. These new homeoboxes are from the labial, proboscipedia, Deformed, Sex combs reduced, fushi tarazu, Antennapedia, Ultrabithorax, abdominal-A and Abdominal-B genes. Phylogenetic signal in the homeobox sequences was assessed and several aspects of sequence evolution were examined. In particular, codon bias was examined and found to exist between the drosophilid species examined here and Anopheles gambiae outgroup sequences. In addition, different patterns of codon bias were detected in homeoboxes interrupted with introns when compared to homeoboxes that are uninterrupted.
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Affiliation(s)
- R DeSalle
- Division of Invertebrates, American Museum of Natural History, 79th Street at Central Park West, New York, NY 10024, USA.
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10
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Dotson EM, Cornel AJ, Willis JH, Collins FH. A family of pupal-specific cuticular protein genes in the mosquito Anopheles gambiae. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 1998; 28:459-472. [PMID: 9718679 DOI: 10.1016/s0965-1748(98)00016-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We have cloned and sequenced members of a cuticular protein multi-gene family from the mosquito Anopheles gambiae. Three genes (agcp2a-c), each approximately 1 kb in length, were found in a 17.4 kb genomic phage clone. Analysis of ten cDNAs revealed that at least four related genes are present. The open reading frame of the genes and cDNAs showed 95% sequence identity. Divergence was observed in the sequence of the 3' ends and the number of copies of two repeated coding sequences. In situ hybridizations with a probe prepared from one of these circular protein genes physically mapped to two loci, 26B on chromosome 2L and 37A on 3R. Transcription of these An. gambiae cuticular protein genes appears to be limited to pharate pupae and the expressed protein(s) is found in early pupae. The deduced amino acid sequence of these proteins contains a hydrophilic region with significant similarity to other cuticular proteins including the pupal-specific cuticular protein, EDG84, of Drosophila melanogaster (Apple and Fristrom).
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Affiliation(s)
- E M Dotson
- Divison of Parasitic Diseases, Centers of Disease Control and Prevention, Chamblee, GA 30341, USA
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11
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Zakharkin SO, Gordadze AV, Korochkina SE, Mathiopoulos KD, Della Torre A, Benes H. Molecular cloning and expression of a hexamerin cDNA from the malaria mosquito, Anopheles gambiae. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 246:719-26. [PMID: 9219531 DOI: 10.1111/j.1432-1033.1997.t01-1-00719.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
During the last larval instar, dipteran insects synthesize two hexamerins rich in aromatic residues, typified by the larval serum proteins 1 and 2 (LSP-1 and LSP-2) of Drosophila melanogaster. We report here the characterization of a complete cDNA sequence encoding a LSP-1-like protein from a lower dipteran insect, the malaria mosquito Anopheles gambiae. The cDNA encodes the subunit of a homohexamer, A. gambiae hexamerin-1.1 (AgHex-1.1), which is a major pupal protein but only a minor constituent of late larval hemolymph. AgHex-1.1 is moderately rich in methionine (3.9%) and particularly rich in aromatic residues (21% Phe+Tyr). Cytogenetic analysis reveals AgHex-1.1 to be encoded by a single-copy gene localized to division 22F within the proximal 2La inversion breakpoint of chromosome 2 of A. gambiae. The AgHex-1.1 transcript is first detected in fourth-instar larvae (L4) and disappears abruptly in early pupae. In situ hybridization shows accumulation of the transcript uniquely in the larval fat body. AgHex-1.1 mRNA is re-expressed in male and female adults at about 10% of the L4 level, with no effect of bloodfeeding in females. The potential roles of AgHex-1.1 in Anopheles development and reproductive maturation are discussed.
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Affiliation(s)
- S O Zakharkin
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock 72205, USA
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12
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Kang D, Romans P, Lee JY. Analysis of a lysozyme gene from the malaria vector mosquito, Anopheles gambiae. Gene X 1996; 174:239-44. [PMID: 8890741 DOI: 10.1016/0378-1119(96)00088-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
A genomic DNA sequence encoding a basic lysozyme was isolated from the malaria vector mosquito Anopheles gambiae by screening a library with a probe prepared by PCR of reverse transcribed adult RNA. The sequence consists of an upstream region of about 2 kb, a coding region containing three exons and two introns, and a short 3' untranslated region. The coding region indicates that this mosquito lysozyme consists of a signal peptide of 20 residues followed by an 120 aa mature protein which is very similar to other basic lysozymes. The two small introns, 67 and 76 bp, are located at evolutionarily conserved sites. RT-PCR indicated that this gene is expressed abundantly in sugar-fed adults, and at considerably lower levels when females have fed on blood. Although it remains to be seen whether this gene is induced by bacterial infection, the surrounding sequence contains six sequence motifs very similar to the consensus binding sites for a transcription factor similar to NF-kappa B that are found associated with most insect immune response genes. This lysozyme gene maps to division 27 on the left arm of polytene chromosome 2L. An ORF unrelated to any animal protein in current data bases was found at the 5' end of the clone.
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Affiliation(s)
- D Kang
- Department of Microbiology, Stockholm University, Sweden
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13
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Besansky NJ, Mukabayire O, Bedell JA, Lusz H. Pegasus, a small terminal inverted repeat transposable element found in the white gene of Anopheles gambiae. Genetica 1996; 98:119-29. [PMID: 8976060 DOI: 10.1007/bf00121360] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Pegasus, a novel transposable element, was discovered as a length polymorphism in the white gene of Anopheles gambiae. Sequence analysis revealed that this 535 bp element was flanked by 8 bp target site duplications and 8 bp perfect terminal inverted repeats similar to those found in many members of the Tc1 family. Its small size and lack of long open reading frames preclude protein coding capacity. Southern analysis and in situ hybridization to polytene chromosomes demonstrated that Pegasus occurs in approximately 30 copies in the genomes of An. gambiae and its sibling species and is homogenous in structure but polymorphic in chromosomal location. Characterization of five additional elements by sequencing revealed nucleotide identities of 95% to 99%. Of 30 Pegasus-containing phage clones examined by PCR, only one contained an element exceeding 535 bp in length, due to the insertion of another transposable element-like sequence. Thus, the majority, if not all, extant Pegasus elements may be defective copies of a complete element whose contemporary existence in An. gambiae is uncertain. No Pegasus-hybridizing sequences were detected in nine other anophelines and three culicines examined, suggesting a very limited taxonomic distribution.
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Affiliation(s)
- N J Besansky
- Division of Parasitic Diseases, Centers for Disease Control and Prevention, Chamblee, GA 30341, USA
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14
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Biessmann H, Donath J, Walter MF. Molecular characterization of the Anopheles gambiae 2L telomeric region via an integrated transgene. INSECT MOLECULAR BIOLOGY 1996; 5:11-20. [PMID: 8630530 DOI: 10.1111/j.1365-2583.1996.tb00035.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
A Drosophila P-element derivative (pUChsneo) integrated into the telomeric region of the left arm of the second chromosome of Anopheles gambiae was used to clone the proximally flanking An. gambiae sequences. Molecular analyses revealed that the pUChsneo construct was partially duplicated and had integrated into a subterminal minisatellite. This satellite has a repeat unit of 820 bp and is located exclusively at the tip of 2L. No sequence similarity to subterminal minisatellites from other dipterans was detected, but some structural features such as tandem subrepeats are shared. The end of the chromosome was mapped with respect to restriction sites in pUChsneo at approximately generation 100 after the integration event. Considering inevitable terminal nucleotide loss due to incomplete DNA replication, we conclude that the chromosome end must have undergone a dramatic elongation process since it was mapped in generation 23.
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Affiliation(s)
- H Biessmann
- Developmental Biology Center, University of California, Irvine, 92717, USA
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15
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Besansky NJ, Bedell JA, Benedict MQ, Mukabayire O, Hilfiker D, Collins FH. Cloning and characterization of the white gene from Anopheles gambiae. INSECT MOLECULAR BIOLOGY 1995; 4:217-231. [PMID: 8825759 DOI: 10.1111/j.1365-2583.1995.tb00027.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
A 14 kb region of genomic DNA containing the X-linked Anopheles gambiae eye colour gene, white, was cloned and sequenced. Genomic clones containing distinct white+ alleles were polymorphic for the insertion of a small transposable element in intron 3, and differed at 1% of nucleotide positions compared. Sequence was also determined from a rare 2914 bp cDNA. Comparison of cDNA and genomic sequences established an intron-exon structure distinct from Drosophila white. Despite a common trend in Anopheles and Drosophila of weak codon bias given low levels of gene expression, codon usage by Anopheles gambiae white was strongly biased. Overall amino acid identity between the predicted mosquito and fruitfly proteins was 64%, but dropped to 14% at the amino terminus. To correlate phenotypically white-eyed strains of A. gambiae with structural lesions in white, five available strains were analysed by PCR and Southern blotting. Although these strains carried allelic mutations, independently generated by gamma radiation (three strains) or spontaneous events (two strains), no white lesions were detected. Significantly, another non-allelic X-linked mutation, causing an identical white-eyed phenotype, has been correlated with a structural defect in the cloned white gene (Benedict et al., 1995). Taken together, these observations suggest that the white-eyed mutants analysed in the present study carry mutations in a second eye colour gene and are most likely white+.
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Affiliation(s)
- N J Besansky
- Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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16
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Beard CB, Crews-Oyen AE, Kumar VK, Collins FH. A cDNA encoding an ADP/ATP carrier from the mosquito Anopheles gambiae. INSECT MOLECULAR BIOLOGY 1994; 3:35-40. [PMID: 8069414 DOI: 10.1111/j.1365-2583.1994.tb00148.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Two cDNAs are described from Anopheles gambiae that correspond to the ADP/ATP carrier or translocase. The clones are identical except for minor differences in the 5' non-coding region and in the lengths of the poly-A tails. They code for mRNAs of 1261 and 1263 bp and contain one open reading frame of 906 bp. A probe made from the 1263 bp cDNA hybridized to bands of approximately 1260 and 1700 bp on developmental Northern blots. The putative 300 amino acid peptide sequence shows from 53.4-78.5% identity to AAC peptide sequences from a range of organisms from Zea mays to human. Both clones mapped to region 26a on the left arm of chromosome 2 in An. gambiae.
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Affiliation(s)
- C B Beard
- Malaria Branch, Centers for Disease Control and Prevention, Atlanta, Georgia 30341-3724
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Affiliation(s)
- J M Crampton
- Wolfson Unit of Molecular Genetics, Liverpool School of Tropical Medicine, UK
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Beard CB, Hamm DM, Collins FH. The mitochondrial genome of the mosquito Anopheles gambiae: DNA sequence, genome organization, and comparisons with mitochondrial sequences of other insects. INSECT MOLECULAR BIOLOGY 1993; 2:103-124. [PMID: 9087549 DOI: 10.1111/j.1365-2583.1993.tb00131.x] [Citation(s) in RCA: 246] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The entire 15,363 bp mitochondrial genome was cloned and sequenced from the mosquito Anopheles gambiae. With respect to the protein-coding genes, rRNA genes and the control region, the gene order was identical to that reported for other insects. There were significant differences, however, in the position and orientation of specific tRNA loci. The overall nucleotide composition was heavily biased towards adenine and thymine, which accounted for 77.6% of all nucleotides. Comparisons were made with the mitochondrial genomes of other insects on the basis genome size and organization, DNA and putative amino acid sequence data, nucleotide substitutions, codon usage and bias, and patterns of AT enrichment.
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Affiliation(s)
- C B Beard
- Centers for Disease Control and Prevention, Public Health Service, US Department of Health and Human Services, Atlanta, GA 30314-3724, USA
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