1,721,069 research outputs found
Delivery of nucleic acids through embryo microinjection in the worldwide agricultural pest insect, ceratitis capitata
Full text linkThe Mediterranean fruit fly (medfly) Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is a pest species with extremely high agricultural relevance. This is due to its reproductive behavior: females damage the external surface of fruits and vegetables when they lay eggs and the hatched larvae feed on their pulp. Wild C. capitata populations are traditionally controlled through insecticide spraying and/or eco-friendly approaches, the most successful being the Sterile Insect Technique (SIT). The SIT relies on mass-rearing, radiation-based sterilization and field release of males that retain their capacity to mate but are not able to generate fertile progeny. The advent and the subsequent rapid development of biotechnological tools, together with the availability of the medfly genome sequence, has greatly boosted our understanding of the biology of this species. This favored the proliferation of new strategies for genome manipulation, which can be applied to population control. In this context, embryo microinjection plays a dual role in expanding the toolbox for medfly control. The ability to interfere with the function of genes that regulate key biological processes, indeed, expands our understanding of the molecular machinery underlying medfly invasiveness. Furthermore, the ability to achieve germ-line transformation facilitates the production of multiple transgenic strains that can be tested for future field applications in novel SIT settings. Indeed, genetic manipulation can be used to confer desirable traits that can, for example, be used to monitor sterile male performance in the field, or that can result in early life-stage lethality. Here we describe a method to microinject nucleic acids into medfly embryos to achieve these two main goals
New genetic tools for improving SIT in Ceratitis capitata: sperm marking and embryonic lethality.
No full textNew genetic tools for improving SIT in Ceratitis capitata: embryonic lethality and sperm marking
No full textEnvironment friendly sterile insect technique (SIT) is being applied effectively as a component of area-wide integrated pest management (AW-IPM) for Ceratitis capitata since 1970s. Nevertheless improved biological strategies are needed to increase the efficacy of AW-IPM. Transgenic approaches should increase and widen the applicability of such programmes to different pest species. In this respect two major strategies are followed: First an approach to cause sterility was designed without interfering with spermatogenesis to maintain males and their sperm as competitive as possible. We followed a strategy, which is based on the expression of a lethal factor under the control of a promoter that is active at early blastoderm stages. The system employs the ectopic expression of a hyperactive proapoptotic gene that causes embryo-specific lethality when driven by the tetracycline-controlled transactivator tTA under the regulation of a cellularization gene enhancer/promoter. The system has been tested successfully in Drosophila melanogaster (Horn & Wimmer 2003). We tried the direct transfer of the Drosophila system to Ceratitis capitata by injecting the respective constructs that carry Drosophila-derived promoters. Unfortunately, the cellularization specific promoters from Drosophila seem not functional in Ceratitis. Therefore, the corresponding enhancers/promoters from Ceratitis were isolated and subsequently the tTA was brought independently under the control of each enhancer/promoter region. These constructs were injected in Ceratitis for further evaluation. Second, we have engineered a medfly strain carrying a sperm marking system. This strain carries two fluorescent markers. One (turboGFP) marker is under the control of the spermatogenesis specific b2-tubulin promoter from Ceratitis and is therefore sperm specifically expressed. The second (DsRed) is under the control of the polyubiquitin promoter of Drosophila. Released males from this strain could be distinguished from wildtype males in the monitoring process.
In addition, monitoring of the mating success of released sterile and fluorescently sperm-marked males by trapping females and examine their spermathecae would be possible. This effective and easily recognizable sperm marking will make novel studies possible on medfly reproductive biology and using sperm marked strains could optimize releasing strategies in SIT-based AW-IPM
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A transgenic sperm marking system in the medfly, as a tool for pest control strategies and sperm use analysis.
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Fluorescent sperm marking to improve the fight against the pest insect Ceratitis capitata (Wiedemann; Diptera : Tephritidae)
No full textThe Sterile Insect Technique (SIT) involving area-wide release of mass-reared and sterilized pest insects has proven successful to reduce, control and eradicate economically important pest species, such as the Mediterranean fruit fly (medfly). For the efficient application, effective monitoring to assess the number and mating success of the released medflies is essential. Here, we report sperm-specific marking systems based on the spermatogenesis-specific Ceratitis capitata beta 2-tubulin (Cc beta 2t) promoter. Fluorescent sperm can be isolated from testes or spermathecae. The marking does not cause general disadvantages in preliminary laboratory competitiveness assays. Therefore, transgenic sperm marking could serve as a major improvement for monitoring medfly SIT programs. The use of such harmless transgenic markers will serve as an ideal initial condition to transfer insect transgenesis technology from the laboratory to field applications. Moreover, effective and easily recognizable sperm marking will make novel studies possible on medfly reproductive biology which will help to further improve SIT programs
Accoppiamenti multipli e modalità d'uso degli spermi in femmine di Ceratitis capitata (Diptera, Tephritidae)
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