Volume 15 Supplement 2
Perspective on the combined use of an independent transgenic sexing and a multifactorial reproductive sterility system to avoid resistance development against transgenic Sterile Insect Technique approaches
© Eckermann et al.; licensee BioMed Central Ltd. 2014
Published: 1 December 2014
The Sterile Insect Technique (SIT) is an accepted species-specific genetic control approach that acts as an insect birth control measure, which can be improved by biotechnological engineering to facilitate its use and widen its applicability. First transgenic insects carrying a single killing system have already been released in small scale trials. However, to evade resistance development to such transgenic approaches, completely independent ways of transgenic killing should be established and combined.
Most established transgenic sexing and reproductive sterility systems are based on the binary tTA expression system that can be suppressed by adding tetracycline to the food. However, to create 'redundant killing' an additional independent conditional expression system is required. Here we present a perspective on the use of a second food-controllable binary expression system - the inducible Q system - that could be used in combination with site-specific recombinases to generate independent transgenic killing systems. We propose the combination of an already established transgenic embryonic sexing system to meet the SIT requirement of male-only releases based on the repressible tTA system together with a redundant male-specific reproductive sterility system, which is activated by Q-system controlled site-specific recombination and is based on a spermatogenesis-specifically expressed endonuclease acting on several species-specific target sites leading to chromosome shredding.
A combination of a completely independent transgenic sexing and a redundant reproductive male sterility system, which do not share any active components and mediate the induced lethality by completely independent processes, would meet the 'redundant killing' criteria for suppression of resistance development and could therefore be employed in large scale long-term suppression programs using biotechnologically enhanced SIT.
KeywordsCRISPR cas9 genetically modified insect genetically modified organism (GMO) insect control insecticide resistance insect pest management molecular entomology quinic acid
Many insects heavily damage agriculture and forestry or transmit deadly diseases to animals and humans. Current control efforts still mostly rely on the use of insecticides, but chemical control is not always harmless and the costs of developing new chemical compounds to overcome the world-wide threat of insecticide resistance are escalating . Moreover, to protect biodiversity the establishment of pest-specific management methods is desirable. The Sterile Insect Technique (SIT) is a species-specific genetic control approach that acts as an insect birth control measure, which relies on the mass rearing, sterilization and field release of large numbers of insects. The competition between released sterile and resident males for mating with wild females leads to the reduction of the reproductive potential. If continued releases of high-quality sterile males in inundating numbers over several consecutive generations are performed, a progressive reduction of the population size and eventually the total eradication of the pest population will occur [2, 3]. SIT is now an accepted component of various integrated approaches to control, suppress, prevent, or even eradicate invasive insect pest species from islands, large fruit production areas, or even complete continents . Classically, both male and female insects were released, particularly because the distinction between male and female pupae is hardly manageable or requires the development of genetic sexing strains . Released females, however, although sterile, sting fruits with their ovipositors or keep blood feeding and potentially transmit diseases as well as compete against wild females for mating with the sterile males . In addition, sterilization is classically achieved by irradiation, a procedure that often renders insects very weak and unfit to compete with the wild mates . Such drawbacks and many years of experience have put forward several key requirements for an efficient SIT application: intensive rearing of large numbers of insects for mass release, the availability of efficient sex-separation methods, sterilization techniques able to handle large numbers of insects with minimal effects on fitness and competitiveness, effective release methods, and efficient marking systems to identify released individuals during monitoring of SIT programs.
Biotechnological engineering of insects makes novel approaches possible to efficiently mark insects as well as selectively produce vigorous and potent sterile males, which are generated by conditional male reproductive sterility in combination with conditional female lethality. This will improve efficacy and widen applicability to further insect pest species [7, 8]. To minimize the concerns coupled with the release of transgenic organisms, SIT programs are actually ideal, as the sterility of the released males will serve as a biological safety mechanism for containment as it impedes the spread of transgenes and allows for a safe deployment [9, 10].
In accordance to this hope for novel successful genetic pest management strategies, the first biotechnologically engineered designer insects have already been released in small scale trials: pink bollworm moths in Arizona, USA , as well as yellow fever mosquitoes in the Grand Cayman Islands , Malaysia , with a currently ongoing release in Brazil [14, 15]. For the release in the Grand Cayman Islands, it has been shown that the sustained release of transgenic mosquitos carrying a dominant lethal gene could successfully suppress a field population  demonstrating the great potential of transgenic SIT approaches. Envisioning the beneficial future use of genetically modified insects, the European Food Safety Authority has recently published a scientific opinion on the guidance on the environmental risk assessment of genetically modified animals including insects . Since reproductive sterility based on lethality systems serves as an intrinsic containment against vertical transmission of transgenes in biotechnologically engineered SIT, its application does not present real concerns in respect to humans and the environment .
Nonetheless, the use of transgenic SIT approaches is still at initial stages and an ongoing large scale use somewhat premature, as potential resistance development might pose a significant threat to the further use of this technology . In the currently released transgenic mosquitoes, the dominant lethality is mediated by the overexpression of a synthetic transcription factor that is deleterious to cells at very high levels reached by auto-activation in a positive feedback loop . This presents just one single killing system based on an unclear mechanism. Since most pest insects produce large numbers of offspring, they have a high propensity to evolve resistance to control measures. Actually classic SIT based on sterilization by irradiation is an exception in the resistance development context, as the radiation-induced breaks of the chromosomes are random and vary among all individuals thus providing built-in redundancy . However, transgenic SIT approaches with defined killing systems are in principle susceptible to resistance development. Thereby, we assume that the released insects still contain functional transgenes and are themselves susceptible to the dominant lethality . The potential break down of transgenic characters during mass rearing is an additional important but different issue for quality control before release. In respect to resistance development the heterogeneous genomes of the field populations are important , which might contain genotypes that lead to suppression or partial suppression of the lethality traits. For the avoidance of behavioural resistance, where wild type insects reject mass-reared insects as mating partners, regular introgression of wild type genetic material into the mass rearing strains has been successful . However, there is also the possibility of biochemical resistance to biotechnologically engineered lethality. Due to the inundation of the population with susceptible alleles by the release of the sterile insects during an ongoing SIT program, only strong resistance-mediating alleles acting dominant and having only low fitness costs propose a threat to SIT programs but are so far only hypothetical .
Nevertheless, insects have successfully developed resistance to synthetic chemicals as well as to microbial agents  and are also likely to develop resistance to transgenic SIT approaches when employed in long-term suppression programs . One strategy to significantly impede or at least delay resistance development could be based on the principle of 'redundant killing' [25, 26]. Therefore, transgenic SIT strains with effective and necessary sterility or lethality traits should only be considered in large scale long-term suppression programs, once completely independent toxicity systems have been combined. Since actually two traits are favourably introduced by transgenesis - female lethality for male only releases as well as reproductive sterility by dominant lethal transgenes - one task is to identify two completely independent ways of mediating them.
Combination of two independent systems: male reproductive sterility and female lethality
A sterile insect in the sense of SIT is defined as "an insect that, as a result of a specific treatment, is unable to reproduce" . A first approach to cause such reproductive sterility by biotechnological engineering was successfully demonstrated in the non-pest insect D. melanogaster . The system is based on the transmission of a transgene combination that causes conditional embryo-specific lethality in the progeny without larval hatching and has successfully been transferred to tephritid fruit flies [29, 30]. This prevents larval damage to fruits and the introgression of transgenes into wild type fruit fly populations. Furthermore, for tephritid fruit flies and mosquitoes, transgenic strains were produced using an autocidal overexpression loop of the protein tTA, which leads to dominant lethality when transgenic males were mated to wild type females [20, 31]. Additional transgenic reproductive sterility systems [32, 33] might be based on species-specific homing endonucleases .
tTA: the commonly used conditionally repressible expression system
The conditionality of the so far established transgenic sexing and reproductive sterility systems is based on a binary expression system, which can be suppressed by supplementing the food with tetracycline (Figure 1). The tetracycline-controlled transactivator (tTA) consists of a bacterial-viral fusion protein  that activates gene expression after binding to a tTA-response element (TRE). The major advantage of this binary expression system is that a food supplement can suppress the activation providing an additional control to the directed gene expression . tTA complexed with tetracycline is prevented from binding to its response element and the downstream gene is not activated. The expression system is thus switched off by supplementing the food with tetracycline, which allows for an additional control on top of the tissue-specific promoter driving tTA expression. Since only small amounts of tetracycline are needed to suppress the expression, this system has become the most favourable expression system to develop transgenic SIT approaches. However, to create a situation of 'redundant killing' based on two completely independent mechanisms to mediate reproductive sterility and female lethality, an additional conditional expression system is necessary.
Second food-controllable expression system: Q system
Render inducible system suitable for transgenic SIT approaches
An inducible system would usually require that the inducer is constantly present to have the system activated. But as this cannot be warranted for a food-additive after release, a temporary induction of the system needs to be stabilized into a continuous expression. For this purpose site-specific recombination systems  can be utilized to stabilize an inducer pulse into a persistent activation. For the flp recombinase (FLP), it was demonstrated in D. melanogaster that a region-specific promoter can be separated from the downstream coding region by a flp-out cassette that contains a transcriptional terminator and is flanked by flp recombinant target sites (FRTs) [56, 57]. The transcriptional terminator prohibits the directed expression mediated by the tissue-specific promoter until FLP removes the flp-out cassette by site-specific recombination of the FRTs that are in direct orientation (Figure 2). The left over single FRT in the 5'UTR does not interfere with effective transcription and translation of the downstream coding sequences [56, 57]. On this basis, the Q binary system can be combined with the FLP mediated transcriptional activation system to stably activate the expression of a gene after a pulse induction with an inducer (Figure 2).
To reduce the number of constructs necessary for such a complex inducible Q and immediate targeted gene expression system, actually the regulatory components of the Q system can be placed into the flp-out cassette (Figure 2) which will also place the Q system components under the same control as the later expressed effector gene . To actually place both regulator genes - QF and QS - into the same construct, the two coding regions can be separated by an internal ribosome entry site (IRES) to allow for a bi-cistronic transcript. Depending on the translational start efficiency of the insect virus IRES compared to the actual capped mRNA , the QS and QF coding sequences should be placed accordingly to make sure that repressor QS will be in surplus to the activator QF.
In D. melanogaster it has been shown that FLP expression driven by the β2 tubulin (β2 tub) promoter is highly efficient to cause cassette flip-out during spermatogenesis leading to the transmission of the activated effector construct into the next generation [56, 57]. Since the β2 tub promoter would also enable the generation of reproductive sterility systems , this promoter would be very suitable for such a complex system. Respective promoters have already been cloned from a number of different tephritid and mosquito species and functionally used for sperm marking purposes [59–61].
To cause reproductive sterility, finally an effector needs to be activated that either causes male sterility by sperm depletion, e.g. by expression of a cell death gene or a cell-specific toxin that is active in the cytoplasm only and has no trans-membrane movement abilities to protect adjacent tissue or predatory organisms [7, 61]. However, as such sterile males would not transfer sperm to females, such females would continue to search further for sperm-providing wild type males. Therefore an effector that would kill the progeny but not the sperm would thus be much more suitable. This will allow for sperm development and transfer and therefore renders the females at least temporarily refractory to subsequent matings with wild type males. Such an effector could be a homing endonuclease (Figure 2) that does not affect spermatogenesis - thus producing functional sperm - but attacks the genome of the zygote or prevents the fusion of the male and female pro-nuclei . This would serve as the best reproductive sterility mechanism as it would cause a dominant early embryonic lethality without affecting the sperm itself by stopping the development of the progeny at the very beginning. Moreover, a homing endonuclease would also be independent in its function from the proposed hyperactive pro-apoptotic gene suggested for the sexing system (Figure 1). However, it should be noted that for an applicable transgenic reproductive sterility system, 100% male sterility needs to be reached, which requires efficient flp recombinase repression in the absence of quinic acid and its effective induction in the presence of quinic acid as well as strong expression of a highly active homing endonuclease.
Partial redundancy of the female lethality and reproductive sterility systems
The described female lethality and reproductive sterility systems will in fact not be fully redundant, as only the female progeny of the released males will indeed have both lethality systems working. In the male progeny only the reproductive sterility providing the homing endonuclease will be active. Thus, rare strong resistance-mediating alleles might be selected in such male progeny and potentially lead to the accumulation of both the resistance allele and the transgenic lethality allele . However, in case of direct linkage between the two lethality systems, which can be achieved by transgene modification based on site-specific recombination , the female lethality in the following generation would severely reduce the chance of accumulation of the lethality allele and thus reduce also the selection of the resistance allele. Since only resistant males would survive, they would be outcompeted by released susceptible SIT males .
Multifactorial reproductive sterility by an endonuclease causing chromosome shredding
Ideally the reproductive sterility system itself should be highly redundant to cause many different lethal mutations similar to the built-in redundancy of radiation-induced sterility . To achieve this, it would be great to have a number of diverse endonucleases or endonuclease target sites causing chromosome shredding . For this, we propose the employment of an endonuclease from the adaptive bacterial immune system using as essential component clustered regularly interspaced short palindromic repeats (CRISPR) [64, 65], which allows bacteria to defend themselves against viruses they encountered before by recognizing and cutting the viral DNA sequences. For the human pathogen Streptococcus pyogenes, it could be shown that a single endonuclease, CRISPR-associated nuclease 9 (Cas9), is sufficient to cleave the target DNA . Since it was shown that Cas9 can be directed to any 'protospacer' sequence followed by a protospacer-adjacent motif (PAM) that has only two required bases (NGG)  by using short guide RNAs (gRNAs) , this CRIPSR/Cas9 system has been successfully employed in many model and non-model organisms to generate gene knock-outs and genome editing . Recently a feature article on this emerging technology has discussed possible uses of the CRIPSR/Cas9 system in gene drives to alter wild populations .
In fact, one of the caveats of the Cas9 technology - the potential lack of specificity leading to off-target effects  - can serve as an additional advantage in the proposed use here, since it might lead to pleiotropic effects harming further genomic loci. Targeting many chromosomal locations will thus provide the intended redundancy bringing the transgene-induced reproductive sterility a step closer to the built-in redundancy of radiation-induced sterility .
The combination of a transgenic sexing system to meet the SIT requirement of male-only releases based on the repressible tTA directed expression system to create female-specific embryonic lethality using a sex-specifically spliced intron and a hyperactive pro-apoptotic gene (Figure 1) together with a reproductive sterility system based on a sperm-specifically expressed endonuclease controlled by the inducible Q-system in combination with site-specific recombination (Figure 2) seems a promising approach. These two systems would not share any active components and the lethality would be mediated by completely independent processes. Therefore, cross-resistance to both lethality-mediating processes is extremely unlikely and resistance development would require at least two independent gene loci with the likelihood of co-existence and selection being significantly reduced . It should be noted, however, that this redundancy is only partial as only the female progeny of respective released males will have both lethality systems at work. While this will still reduce the likelihood of accumulating transgenic lethal alleles and resistance alleles, we propose an additional level of redundancy for the reproductive sterility system using the CRISPR/Cas9 endonuclease system targeting several chromosomal locations to induce chromosome shredding in the sperm (Figure 3).
A transgenic SIT approach using independent lethality systems would meet the 'redundant killing' criteria for suppression of resistance development and could therefore be employed in large scale long-term suppression programs.
The project profited from discussions at the International Atomic Energy Agency funded meetings of the Coordinated Research Projects ''The Use of Molecular Tools to Improve the Effectiveness of SIT'' and ''Development and Evaluation of Improved Strains of Insect Pests for SIT". This work was partially supported by the German Academic Exchange Service (DAAD) with a short term scholarship to IMC.
This article has been published as part of BMC Genetics Volume 15 Supplement 2, 2014: Development and evaluation of improved strains of insect pests for SIT. The full contents of the supplement are available online at http://www.biomedcentral.com/bmcgenet/supplements/15/S2.
Publication of this supplement was funded by the International Atomic Energy Agency. The peer review process for articles published in this supplement was overseen by the Supplement Editors in accordance with BioMed Central's peer review guidelines for supplements. The Supplement Editors declare that they have no competing interests.
- Pedigo LP: Entomology and Pest Management. 2002, Upper Saddle River: Prentice Hall, 4Google Scholar
- Knipling EF: Possibilities of insect control or eradication through the use of sexually sterile males. J Econ Entomol. 1955, 48: 459-462. 10.1093/jee/48.4.459.View ArticleGoogle Scholar
- Dyck VA, Hendrichs J, Robinson AS: Sterile insect technique - principles and practice in area-wide integrated pest management. 2005, Dordrecht, NL: SpringerGoogle Scholar
- World-Wide Directory of SIT Facilities (DIR-SIT). [http://nucleus.iaea.org/sites/naipc/dirsit/SitePages/Home.aspx]
- Franz G: Genetic sexing Strains in Mediterranean Fruit Fly, an Example for Other Species Amendable to Large-Scale Rearing for the Sterile Insect Technique. Sterile insect technique - principles and practice in area-wide integrated pest management. Edited by: Dyck VA, Hendrichs J, Robinson AS. 2005, Dordrecht, NL: Springer, 427-451.Google Scholar
- Parker A, Mehta K: Sterile insect technique: a model for dose optimization for improved sterile insect quality. Fla Entomol. 2007, 90: 88-95. 10.1653/0015-4040(2007)90[88:SITAMF]2.0.CO;2.View ArticleGoogle Scholar
- Handler AM: Prospects for using genetic transformation for improved SIT and new biocontrol methods. Genetica. 2002, 116: 137-49. 10.1023/A:1020924028450.View ArticlePubMedGoogle Scholar
- Schetelig MF, Wimmer EA: Insect Transgenesis and the Sterile Insect Technique. Insect Biotechnology. Edited by: Vilcinskas A. 2011, Dordrecht, NL: Springer Verlag, 169-194.View ArticleGoogle Scholar
- Wimmer EA: Eco-friendly insect management. Nat Biotechnol. 2005, 23: 432-433. 10.1038/nbt0405-432.View ArticlePubMedGoogle Scholar
- Alphey L, Benedict M, Bellini R, Clark GG, Dame DA, Service MW, Dobson SL: Sterile-insect methods for control of mosquito-borne diseases: an analysis. Vector Borne Zoonotic Dis. 2010, 295-311. 10Google Scholar
- Simmons GS, McKemey AR, Morrison NI, O'Connell S, Tabashnik BE, Claus J, Fu G, Tang G, Sledge M, Walker AS, Phillips CE, Miller ED, Rose RI, Staten RT, Donnelly CA, Alphey L: Field performance of a genetically engineered strain of pink bollworm. PLoS One. 2011, 6: e24110-10.1371/journal.pone.0024110.PubMed CentralView ArticlePubMedGoogle Scholar
- Harris AF, Nimmo D, McKemey AR, Kelly N, Scaife S, Donnelly CA, Beech C, Petrie WD, Alphey L: Field performance of engineered male mosquitoes. Nat Biotechnol. 2011, 29: 1034-7. 10.1038/nbt.2019.View ArticlePubMedGoogle Scholar
- Lacroix R, McKemey AR, Raduan N, Kwee Wee L, Hong Ming W, Guat Ney T, Rahidah AAS, Salman S, Subramaniam S, Nordin O, Hanum ATN, Angamuthu C, Marlina Mansor S, Lees RS, Naish N, Scaife S, Gray P, Labbé G, Beech C, Nimmo D, Alphey L, Vasan SS, Han Lim L, Wasi AN, Murad S: Open field release of genetically engineered sterile male Aedes aegypti in Malaysia. PLoS One. 2012, 7: e42771-10.1371/journal.pone.0042771.PubMed CentralView ArticlePubMedGoogle Scholar
- Mumford JD: Science, regulation, and precedent for genetically modified insects. PLoS Negl Trop Dis. 2012, 6: e1504-10.1371/journal.pntd.0001504.PubMed CentralView ArticlePubMedGoogle Scholar
- Carvalho DO, Nimmo D, Naish N, McKemey AR, Gray P, Wilke AB, Marrelli MT, Virginio JF, Alphey L, Capurro ML: Mass production of genetically modified Aedes aegypti for field releases in Brazil. J Vis Exp. 2014, 83: e3579-PubMedGoogle Scholar
- Harris AF, McKemey AR, Nimmo D, Curtis Z, Black I, Morgan SA, Oviedo MN, Lacroix R, Naish N, Morrison NI, Collado A, Stevenson J, Scaife S, Dafa'alla T, Fu G, Phillips C, Miles A, Raduan N, Kelly N, Beech C, Donnelly CA, Petrie WD, Alphey L: Successful suppression of a field mosquito population by sustained release of engineered male mosquitoes. Nat Biotechnol. 2012, 30: 828-30. 10.1038/nbt.2350.View ArticlePubMedGoogle Scholar
- European Food Safety Authority Panel on Genetically Modified Organisms (GMO): Guidance on the environmental risk assessment of genetically modified animals. EFSA Journal. 2013, 11: 3200-Google Scholar
- Wilke AB1, Marrelli MT: Genetic control of mosquitoes: population suppression strategies. Rev Inst Med Trop Sao Paulo. 2012, 54: 287-92. 10.1590/S0036-46652012000500009.View ArticlePubMedGoogle Scholar
- Reeves RG, Denton JA, Santucci F, Bryk J, Reed FA: Scientific standards and the regulation of genetically modified insects. PLoS Negl Trop Dis. 2012, 6: e1502-10.1371/journal.pntd.0001502.PubMed CentralView ArticlePubMedGoogle Scholar
- Phuc HK, Andreasen MH, Burton RS, Vass C, Epton MJ, Pape G, Fu G, Condon KC, Scaife S, Donnelly CA, Coleman PG, White-Cooper H, Alphey L: Late-acting dominant lethal genetic systems and mosquito control. BMC Biol. 2007, 5: 11-10.1186/1741-7007-5-11.PubMed CentralView ArticlePubMedGoogle Scholar
- Benedict MQ, Robinson AS: The first releases of transgenic mosquitoes: an argument for the sterile insect technique. Trends Parasitol. 2003, 19: 349-55. 10.1016/S1471-4922(03)00144-2.View ArticlePubMedGoogle Scholar
- Alphey N, Bonsall MB, Alphey L: Modeling resistance to genetic control of insects. J Theor Biol. 2011, 270: 42-55. 10.1016/j.jtbi.2010.11.016.View ArticlePubMedGoogle Scholar
- MacIntosh SC: Managing the risk of insect resistance to transgenic insect control traits: practical approaches in local environments. Pest Management Science. 2010, 66: 100-106. 10.1002/ps.1854.View ArticlePubMedGoogle Scholar
- Robinson AS, Hendrichs J: Prospects for the future development and application of the sterile insect technique. Sterile insect technique - principles and practice in area-wide integrated pest management. Edited by: Dyck VA, Hendrichs J, Robinson AS. 2005, Dordrecht, NL: Springer, 727-760.Google Scholar
- Gould F: Sustainability of transgenic insecticidal cultivars: integrating pest genetics and ecology. Annu Rev Entomol. 1998, 43: 701-26. 10.1146/annurev.ento.43.1.701.View ArticlePubMedGoogle Scholar
- Zhao JZ, Cao J, Li Y, Collins HL, Roush RT, Earle ED, Shelton AM: Transgenic plants expressing two Bacillus thuringiensis toxins delay insect resistance evolution. Nat Biotechnol. 2003, 21: 1493-7. 10.1038/nbt907.View ArticlePubMedGoogle Scholar
- Food and Agriculture Organization of the United Nations (FAO): Glossary of phytosanitary terms. 2007, Secretariat of the International Plant Protection Convention (IPPC), ISPM No 5Google Scholar
- Horn C, Wimmer EA: A transgene-based, embryo-specific lethality system for insect pest management. Nat Biotechnol. 2003, 21: 64-70.View ArticlePubMedGoogle Scholar
- Schetelig MF, Caceres C, Zacharopoulou A, Franz G, Wimmer EA: Conditional embryonic lethality to improve the sterile insect technique in Ceratitis capitata (Diptera: Tephritidae). BMC Biology. 2009, 7: 4-10.1186/1741-7007-7-4.PubMed CentralView ArticlePubMedGoogle Scholar
- Schetelig MF, Handler AM: Strategy for enhanced transgenic strain development for embryonic conditional lethality in Anastrepha suspensa. Proc Natl Acad Sci USA. 2012, 9348-53. 109Google Scholar
- Gong P, Epton MJ, Fu G, Scaife S, Hiscox A, Condon KC, Condon GC, Morrison NI, Kelly DW, Dafa'alla T, Coleman PG, Alphey L: A dominant lethal genetic system for autocidal control of the Mediterranean fruitfly. Nat Biotechnol. 2005, 23: 453-6. 10.1038/nbt1071.View ArticlePubMedGoogle Scholar
- Catteruccia F, Crisanti A, Wimmer EA: Transgenic technologies to induce sterility. Malar J. 2009, 8 (Suppl 2): S7-10.1186/1475-2875-8-S2-S7.PubMed CentralView ArticlePubMedGoogle Scholar
- Nolan T, Papathanos P, Windbichler N, Magnusson K, Benton J, Catteruccia F, Crisanti A: Developing transgenic Anopheles mosquitoes for the sterile insect technique. Genetica. 2011, 139: 33-9. 10.1007/s10709-010-9482-8.View ArticlePubMedGoogle Scholar
- Windbichler N, Papathanos PA, Crisanti A: Targeting the × chromosome during spermatogenesis induces Y chromosome transmission ratio distortion and early dominant embryo lethality in Anopheles gambiae. PLoS Genet. 2008, 4: e1000291-10.1371/journal.pgen.1000291.PubMed CentralView ArticlePubMedGoogle Scholar
- Heinrich JC, Scott MJ: A repressible female-specific lethal genetic system for making transgenic insect strains suitable for a sterile-release program. Proc Natl Acad Sci USA. 2000, 97: 8229-8232. 10.1073/pnas.140142697.PubMed CentralView ArticlePubMedGoogle Scholar
- Thomas DD, Donnelly CA, Wood RJ, Alphey LS: Insect population control using a dominant, repressible, lethal genetic system. Science. 2000, 287: 2474-2476. 10.1126/science.287.5462.2474.View ArticlePubMedGoogle Scholar
- Fu G, Condon KC, Epton MJ, Gong P, Jin L, Condon GC, Morrison NI, Dafa'alla TH, Alphey L: Female-specific insect lethality engineered using alternative splicing. Nat Biotechnol. 2007, 25: 353-7. 10.1038/nbt1283.View ArticlePubMedGoogle Scholar
- Ant T, Koukidou M, Rempoulakis P, Gong HF, Economopoulos A, Vontas J, Alphey L: Control of the olive fruit fly using genetics-enhanced sterile insect technique. BMC Biology. 2012, 10: 51-10.1186/1741-7007-10-51.PubMed CentralView ArticlePubMedGoogle Scholar
- Li F, Wantuch HA, Linger RJ, Belikoff EJ, Scott MJ: Transgenic sexing system for genetic control of the Australian sheep blow fly Lucilia cuprina. Insect Biochem Mol Biol. 2014, 51: 80-8.View ArticlePubMedGoogle Scholar
- Tan A, Fu G, Jin L, Guo Q, Li Z, Niu B, Meng Z, Morrison NI, Alphey L, Huang Y: Transgene-based, female-specific lethality system for genetic sexing of the silkworm, Bombyx mori. Proc Natl Acad Sci USA. 2013, 110: 6766-70. 10.1073/pnas.1221700110.PubMed CentralView ArticlePubMedGoogle Scholar
- Schetelig MF, Handler AM: A transgenic embryonic sexing system for Anastrepha suspensa (Diptera: Tephritidae). Insect Biochem Mol Bio. 2012, 790-5. 42Google Scholar
- Ogaugwu CE, Schetelig MF, Wimmer EA: Transgenic sexing system for Ceratitis capitata (Diptera: Tephritidae) based on female-specific embryonic lethality. Insect Biochem Mol Biol. 2013, 43: 1-8. 10.1016/j.ibmb.2012.10.010.View ArticlePubMedGoogle Scholar
- Koukidou M, Alphey L: Practical applications of insects' sexual development for pest control. Sex Dev. 2014, 8: 127-36. 10.1159/000357203.View ArticlePubMedGoogle Scholar
- Pane A, Salvemini M, Delli BP, Polito C, Saccone G: The transformer gene in Ceratitis capitata provides a genetic basis for selecting and remembering the sexual fate. Development. 2002, 129: 3715-3725.PubMedGoogle Scholar
- Schetelig MF, Milano A, Saccone G, Handler AM: Male only progeny in Anastrepha suspensa by RNAi-induced sex reversion of chromosomal females. Insect Biochem Mol Biol. 2012, 42: 51-7. 10.1016/j.ibmb.2011.10.007.View ArticlePubMedGoogle Scholar
- Gossen M, Bujard H: Tight control of gene expression in mammalian cells by tetracycline-responsive promoters. Proc Natl Acad Sci USA. 1992, 89: 5547-5551. 10.1073/pnas.89.12.5547.PubMed CentralView ArticlePubMedGoogle Scholar
- Bello B, Resendez-Perez D, Gehring WJ: Spatial and temporal targeting of gene expression in Drosophila by means of a tetracycline-dependent transactivator system. Development. 1998, 125: 2193-2202.PubMedGoogle Scholar
- Potter CJ, Tasic B, Russler EV, Liang L, Luo L: The Q system: a repressible binary system for transgene expression, lineage tracing, and mosaic analysis. Cell. 2010, 141: 536-48. 10.1016/j.cell.2010.02.025.PubMed CentralView ArticlePubMedGoogle Scholar
- Potter CJ, Luo L: Using the Q system in Drosophila melanogaster. Nat Protoc. 2011, 6: 1105-20. 10.1038/nprot.2011.347.PubMed CentralView ArticlePubMedGoogle Scholar
- Wei X1, Potter CJ, Luo L, Shen K: Controlling gene expression with the Q repressible binary expression system in Caenorhabditis elegans. Nat Methods. 2012, 9: 391-5. 10.1038/nmeth.1929.View ArticlePubMedGoogle Scholar
- Giles NH, Case ME, Baum J, Geever R, Huiet L, Patel V, Tyler B: Gene organization and regulation in the qa (quinic acid) gene cluster of Neurospora crassa. Microbiol Rev. 1985, 49: 338-58.PubMed CentralPubMedGoogle Scholar
- Zulet A, Zabalza A, Royuela M: Phytotoxic and metabolic effects of exogenous quinate on Pisum sativum L. J Plant Growth Regul. 2013, 32: 779-788. 10.1007/s00344-013-9345-5.View ArticleGoogle Scholar
- Albertini MV, Carcouet E, Pailly O, Gambotti C, Luro F, Berti L: Changes in organic acids and sugars during early stages of development of acidic and acidless citrus fruit. J Agric Food Chem. 2006, 54: 8335-9. 10.1021/jf061648j.View ArticlePubMedGoogle Scholar
- Giles NH, Geever RF, Asch DK, Avalos J, Case ME: The Wilhelmine E. Key 1989 invitational lecture. Organization and regulation of the qa (quinic acid) genes in Neurospora crassa and other fungi. J Hered. 1991, 82: 1-7. 10.1093/jhered/82.1.1.View ArticlePubMedGoogle Scholar
- Schetelig MF, Götschel F, Viktorinova I, Handler AM, Wimmer EA: Recombination technologies for enhanced transgene stability in bioengineered insects. Genetica. 2011, 139: 71-78. 10.1007/s10709-010-9494-4.PubMed CentralView ArticlePubMedGoogle Scholar
- Kosman D, Small S: Concentration-dependent patterning by an ectopic expression domain of the Drosophila gap gene knirps. Development. 1997, 124: 1343-54.PubMedGoogle Scholar
- Wimmer EA, Cohen SM, Jäckle H, Desplan C: buttonhead does not contribute to a combinatorial code proposed for Drosophila head development. Development. 1997, 124: 1509-1517.PubMedGoogle Scholar
- Carter JR, Fraser TS, Fraser MJ: Examining the relative activity of several dicistrovirus intergenic internal ribosome entry site elements in uninfected insect and mammalian cell lines. J Gen Virol. 2008, 89: 3150-5. 10.1099/vir.0.2008/003921-0.View ArticlePubMedGoogle Scholar
- Catteruccia F, Benton JP, Crisanti A: An Anopheles transgenic sexing strain for vector control. Nat Biotechnol. 2005, 23: 1414-7. 10.1038/nbt1152.View ArticlePubMedGoogle Scholar
- Scolari F, Schetelig MF, Bertin S, Malacrida AR, Gasperi G, Wimmer EA: Fluorescent sperm marking to improve the fight against the pest insect Ceratitis capitata (Wiedemann; Diptera: Tephritidae). N Biotechnol. 2008, 25: 76-84. 10.1016/j.nbt.2008.02.001.View ArticlePubMedGoogle Scholar
- Zimowska GJ, Nirmala X, Handler AM: The beta2-tubulin gene from three tephritid fruit fly species and use of its promoter for sperm marking. Insect Biochem Mol Biol. 2009, 39: 508-515. 10.1016/j.ibmb.2009.05.004.View ArticlePubMedGoogle Scholar
- Schetelig MF, Scolari F, Handler AM, Kittelmann S, Gasperi G, Wimmer EA: Site-specific recombination for the modification of transgenic strains of the Mediterranean fruit fly Ceratitis capitata. Proc Natl Acad Sci USA. 2009, 106: 18171-6. 10.1073/pnas.0907264106.PubMed CentralView ArticlePubMedGoogle Scholar
- Galizi R, Doyle LA, Menichelli M, Bernardini F, Deredec A, Burt A, Stoddard BL, Windbichler N, Crisanti A: A synthetic sex ratio distortion system for the control of the human malaria mosquito. Nat Commun. 2014, 5: 3977-PubMed CentralView ArticlePubMedGoogle Scholar
- Horvath P, Barrangou R: CRISPR/Cas, the immune system of bacteria and archaea. Science. 2010, 327: 167-70. 10.1126/science.1179555.View ArticlePubMedGoogle Scholar
- Wiedenheft B, Sternberg SH, Doudna JA: RNA-guided genetic silencing systems in bacteria and archaea. Nature. 2012, 482: 331-8. 10.1038/nature10886.View ArticlePubMedGoogle Scholar
- Deltcheva E, Chylinski K, Sharma CM, Gonzales K, Chao Y, Pirzada ZA, Eckert MR, Vogel J, Charpentier E: CRISPR RNA maturation by trans-encoded small RNA and host factor RNase III. Nature. 2011, 471: 602-7. 10.1038/nature09886.PubMed CentralView ArticlePubMedGoogle Scholar
- Jinek M, Chylinski K, Fonfara I, Hauer M, Doudna JA, Charpentier E: A programmable dual-RNA-guided DNA endonuclease in adaptive bacterial immunity. Science. 2012, 337: 816-21. 10.1126/science.1225829.View ArticlePubMedGoogle Scholar
- Fu Y, Sander JD, Reyon D, Cascio VM, Joung JK: Improving CRISPR-Cas nuclease specificity using truncated guide RNAs. Nat Biotechnol. 2014, 279-84. 32Google Scholar
- Harrison MM, Jenkins BV, O'Connor-Giles KM, Wildonger J: A CRISPR view of development. Genes Dev. 2014, 1859-1872. 28Google Scholar
- Esvelt KM, Smidler AL, Catteruccia F, Church GM: Concerning RNA-guided gene drives for the alteration of wild populations. Elife. 2014, 17: e03401-Google Scholar
- Kondo S, Ueda R: Highly improved gene targeting by germline-specific Cas9 expression in Drosophila. Genetics. 2013, 195: 715-21. 10.1534/genetics.113.156737.PubMed CentralView ArticlePubMedGoogle Scholar
- Port F, Chen HM, Lee T, Bullock SL: Optimized CRISPR/Cas tools for efficient germline and somatic genome engineering in Drosophila. Proc Natl Acad Sci USA. 2014, 111: E2967-76. 10.1073/pnas.1405500111.PubMed CentralView ArticlePubMedGoogle Scholar
- Renkawitz-Pohl R, Hempel L, Hollmann M, Schäfer MA: Spermatogenesis. Comprehensive Molecular Insect Science, vol 1 Reproduction and Development. Edited by: Gilbert LI, Iatrou K, Gill SS. 2005, Amsterdam:Elsevier Pergamon, 157-177.View ArticleGoogle Scholar
- Sampson TR, Weiss DS: Exploiting CRISPR/Cas systems for biotechnology. Bioessays. 2014, 36: 34-8. 10.1002/bies.201300135.PubMed CentralView ArticlePubMedGoogle Scholar
- Xu T, Li Y, Van Nostrand JD, He Z, Zhou J: Cas9-based tools for targeted genome editing and transcriptional control. Appl Environ Microbiol. 2014, 1544-52. 80Google Scholar
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