Publications
76 results found
Magnusson K, Mendes AM, Windbichler N, et al., 2011, Transcription Regulation of Sex-Biased Genes during Ontogeny in the Malaria Vector Anopheles gambiae, Plos One, Vol: 6
Nolan T, Petris E, Mueller H-M, et al., 2011, Analysis of two novel midgut-specific promoters driving transgene expression in anopheles stephensi mosquitoes, PLoS ONE, Vol: 6, ISSN: 1932-6203
BackgroundTissue-specific promoters controlling the expression of transgenes in Anopheles mosquitoes represent a valuable tool both for studying the interaction between these malaria vectors and the Plasmodium parasites they transmit and for novel malaria control strategies based on developing Plasmodium-refractory mosquitoes by expressing anti-parasitic genes. With this aim we have studied the promoter regions of two genes from the most important malaria vector, Anopheles gambiae, whose expression is strongly induced upon blood feeding.ResultsWe analysed the A. gambiae Antryp1 and G12 genes, which we have shown to be midgut-specific and maximally expressed at 24 hours post-bloodmeal (PBM). Antryp1, required for bloodmeal digestion, encodes one member of a family of 7 trypsin genes. The G12 gene, of unknown function, was previously identified in our laboratory in a screen for genes induced in response to a bloodmeal. We fused 1.1 kb of the upstream regions containing the putative promoter of these genes to reporter genes and transformed these into the Indian malaria vector A. stephensi to see if we could recapitulate the expression pattern of the endogenous genes. Both the Antryp1 and G12 upstream regions were able to drive female-predominant, midgut-specific expression in transgenic mosquitoes. Expression of the Antryp1-driven reporter in transgenic A. stephensi lines was low, undetectable by northern blot analysis, and failed to fully match the induction kinetics of the endogenous Antryp1 gene in A. gambiae. This incomplete conservation of expression suggests either subtle differences in the transcriptional machinery between A. stephensi and A. gambiae or that the upstream region chosen lacked all the control elements. In contrast, the G12 upstream region was able to faithfully reproduce the expression profile of the endogenous A. gambiae gene, showing female midgut specificity in the adult mosquito and massive induction PBM, peaking at 24 hours.ConclusionsOur stu
Magnusson K, Mendes AM, Windbichler N, et al., 2011, Transcription regulation of sex-biased genes during ontogeny in the malaria vector ., PLoS ONE, Pages: e21572-e21572
Thompson FJ, Barker GLA, Nolan T, et al., 2009, Transcript profiles of long- and short-lived adults implicate protein synthesis in evolved differences in ageing in the nematode Strongyloides ratti, Mechanisms of Ageing and Development, Vol: 130, Pages: 167-172
Nolan T, Cecere G, Mancone C, et al., 2008, The RNA-dependent RNA polymerase essential for post-transcriptional gene silencing in Neurospora crassa interacts with replication protein A, Nucleic Acids Research, Vol: 36, Pages: 532-538, ISSN: 0305-1048
Post-transcriptional gene silencing (PTGS) pathways play a role in genome defence and have been extensively studied, yet how repetitive elements in the genome are identified is still unclear. It has been suggested that they may produce aberrant transcripts (aRNA) that are converted by an RNA-dependent RNA polymerase (RdRP) into double-stranded RNA (dsRNA), the essential intermediate of PTGS. However, how RdRP enzymes recognize aberrant transcripts remains a key question. Here we show that in Neurospora crassa the RdRP QDE-1 interacts with Replication Protein A (RPA), part of the DNA replication machinery. We show that both QDE-1 and RPA are nuclear proteins and that QDE-1 is specifically recruited onto the repetitive transgenic loci. We speculate that this localization of QDE-1 could allow the in situ production of dsRNA using transgenic nascent transcripts as templates, as in other systems. Supporting a link between the two proteins, we found that the accumulation of short interfering RNAs (siRNAs), the hallmark of silencing, is dependent on an ongoing DNA synthesis. The interaction between QDE-1 and RPA is important since it should guide further studies aimed at understanding the specificity of the RdRP and it provides for the first time a potential link between a PTGS component and the DNA replication machinery.
Scali C, Nolan T, Sharakhov I, et al., 2007, Post-integration behavior of a Minos transposon in the malaria mosquito Anopheles stephensi, Molecular Genetics and Genomics, Vol: 278, Pages: 575-584
Catalanotto C, Nolan T, Cogoni C, 2006, Homology effects in Neurospora crassa, Fems Microbiology Letters, Vol: 254, Pages: 182-189
Lombardo F, Nolan T, Lycett G, et al., 2005, An Anopheles gambiae salivary gland promoter analysis in Drosophila melanogaster and Anopheles stephensi., Insect Mol Biol, Vol: 14, Pages: 207-216, ISSN: 0962-1075
Regulatory regions driving gene expression in specific target organs of the African malaria vector Anopheles gambiae are of critical relevance for studies on Plasmodium-Anopheles interactions as well as to devise strategies for blocking malaria parasite development in the mosquito. In order to identify an appropriate salivary gland promoter we analysed the transactivation properties of genomic fragments located just upstream of the An. gambiae female salivary gland-specific genes AgApy and D7r4. An 800 bp fragment from the AgApy gene directed specific expression of the LacZ reporter gene in the salivary glands of transgenic Anopheles stephensi. However, expression levels were lower than expected and the transgene was expressed in the proximal-rather than in the distal-lateral lobes of female glands. Surprisingly, a promoter fragment from the D7r4 gene conferred strong tissue-specific expression in Drosophila melanogaster but only low transcription levels in transgenic An. stephensi. These results imply a certain conservation of gland-specific control elements between the fruit fly and the mosquito suggesting that an increased degree of complexity, probably connected to the evolution of haematophagy, underlies the regulation of tissue-specific expression in mosquito female salivary glands.
Nolan T, Braccini L, Azzalin G, et al., 2005, The post-transcriptional gene silencing machinery functions independently of DNA methylation to repress a LINE1-like retrotransposon in neurospora crassa, Nucleic Acids Research, Vol: 33, Pages: 1564-1573, ISSN: 0305-1048
Post-transcriptional gene silencing (PTGS) involving small interfering RNA (siRNA)-directed degradation of RNA transcripts and transcriptional silencing via DNA methylation have each been proposed as mechanisms of genome defence against invading nucleic acids, such as transposons and viruses. Furthermore, recent data from plants indicates that many transposons are silenced via a combination of the two mechanisms, and siRNAs can direct methylation of transposon sequences. We investigated the contribution of DNA methylation and the PTGS pathway to transposon control in the filamentous fungus Neurospora crassa. We found that repression of the LINE1-like transposon, Tad, requires the Argonaute protein QDE2 and Dicer, each of which are required for transgene-induced PTGS (quelling) in N.crassa. Interestingly, unlike quelling, the RNA-dependent RNA polymerase QDE1 and the RecQ DNA helicase QDE3 were not required for Tad control, suggesting the existence of specialized silencing pathways for diverse kinds of repetitive elements. In contrast, Tad elements were not significantly methylated and the DIM2 DNA methyltransferase, responsible for all known DNA methylation in Neurospora, had no effect on Tad control. Thus, an RNAi-related transposon silencing mechanism operates during the vegetative phase of N.crassa that is independent of DNA methylation, highlighting a major difference between this organism and other methylation-proficient species.
Lombardo F, Nolan T, Lycett G, et al., 2005, An Anopheles gambiae salivary gland promoter analysis in Drosophila melanogaster and Anopheles stephensi, Insect Molecular Biology, Vol: 14, Pages: 207-216
Nolan T, Cogoni C, 2004, The long hand of the small RNAs reaches into several levels of gene regulation, Biochemistry and Cell Biology-Biochimie Et Biologie Cellulaire, Vol: 82, Pages: 472-481
Nolan T, Bower TM, Brown AE, et al., 2002, piggyBac-mediated germline transformation of the malaria mosquito Anopheles stephensi using the red fluorescent protein dsRED as a selectable marker, Journal of Biological Chemistry, Vol: 277, Pages: 8759-8762
Moreira LA, Ito J, Ghosh A, et al., 2002, Bee venom phospholipase inhibits malaria parasite development in transgenic mosquitoes, Journal of Biological Chemistry, Vol: 277, Pages: 40839-40843
Catteruccia F, Nolan T, Blass C, et al., 2000, Erratum: Toward Anopheles transformation: Minos element activity in anopheline cells and embryos (Proceedings of the National Academy of Sciences of the United States of America (February 29, 2000) 97:5 (2157-2162)), Proceedings of the National Academy of Sciences of the United States of America, Vol: 97, ISSN: 0027-8424
- Cite
- Citations: 1
Catteruccia F, Nolan T, Loukeris TG, et al., 2000, Stable germline transformation of the malaria mosquito Anopheles stephensi, Nature, Vol: 405, Pages: 959-962
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