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Archive - Nov 28, 2015

Black Widow DNA & Prey DNA Extracted from Spider Webs & Sequenced; DNA Detectable At Least 88 Days After Living Species No Longer Present; Multiple Possible Applications Envisioned, Particularly Environmental Monitoring

Scientists extracted DNA from spider webs to identify the web's spider architect and the prey that crossed it, according to this proof-of-concept study published on November 25, 2015 in the open-access journal PLOS ONE by Charles C. Y. Xu from the University of Notre Dame, and colleagues. The article is titled “Spider Web DNA: A New Spin on Noninvasive Genetics of Predator and Prey.” Noninvasive genetic sampling enables biomonitoring without the need to directly observe or disturb target organisms. The authors of this study used three black widow spiders fed house crickets to noninvasively extract, amplify, and sequence mitochondrial DNA from their spider web samples, which identified both the spider and its prey to the species level. The detectability of spider DNA did not differ between assays and spider and prey DNA remained detectable at least 88 days after living organisms were no longer present on the web. The authors suggest that these results may encourage further studies that could lead to practical applications in conservation research, pest management, biogeography studies, and biodiversity assessments. However, further testing of field-collected spider webs from more species and habitats is needed to evaluate the generality of these findings. Xu says: "Sticky spider webs are natural DNA samplers, trapping nearby insects and other things blowing in the wind. We see potential for broad environmental monitoring because spiders build webs in so many places." The image shows a Southern black widow spider (Latrodectus mactans) with its prey house cricket (Acheta domesticus) trapped in spider web. (Credit: Scott Camazine).

[Press release] [PLOS ONE article]

CRISPR/Cas9 Gene Editing Enables Creation of Mosquito Strain with Malaria-Blocking Genes; Technique Results in Malaria-Blocking Genes Being Passed on to an “Astonishing” 99.5% of Mosquito Progeny

Using the ground-breaking CRISPR/Cas9 gene editing technique, University of California scientists have created a strain of mosquitoes capable of rapidly introducing malaria-blocking genes into a mosquito population through its progeny, ultimately eliminating the insects' ability to transmit the disease to humans. This new model represents a notable advance in the effort to establish an anti-malarial mosquito population, which with further development could help eradicate a disease that sickens millions worldwide each year. To create this breed, researchers at the Irvine and San Diego campuses inserted a DNA element into the germ line of Anopheles stephensi mosquitoes that resulted in the genes preventing malaria transmission being passed on to an astonishing 99.5 percent of offspring. The transferred genes included dual anti-Plasmodium falciparum effector genes, a marker gene, and the autonomous gene-drive components. A. stephensi is a leading malaria vector in Asia. The study underlines the growing utility of the CRISPR method, a powerful gene editing tool that allows access to a cell's nucleus to snip DNA to either replace mutated genes or insert new ones. Results were published online on November 23, 2015 in PNAS. The article is titled “Highly Efficient Cas9-Mediated Gene Drive for Population Modification of the Malaria Vector Mosquito Anopheles stephensi.” "This opens up the real promise that this technique can be adapted for eliminating malaria," said Anthony James, Ph.D., Distinguished Professor of Molecular Biology & Biochemistry and Microbiology & Molecular Genetics at UC Irvine (UCI). For nearly 20 years, the James lab has focused on engineering anti-disease mosquitoes.