PubMed · 10925638
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J Smith. 2000-06-26. [Ticks or bugs?].. https://pubmed.ncbi.nlm.nih.gov/10925638/
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The two-spotted spider mite, Tetranychus urticae, is a major pest and an emerging genetic model. Recent CRISPR-Cas9 advances, especially the SYNCAS method for maternal delivery of Cas9 ribonucleoproteins, have enabled precise genome editing in this and other difficult-to-transform arthropods. Yet SYNCAS-mediated knockins vary in efficiency, possibly due to competition between DNA repair pathways, whose mechanisms in T. urticae and other chelicerates remain unknown. Here, we provide the first functional analysis of double-strand break repair in a chelicerate. Loss of DNA polymerase theta (Polθ) redirects repair almost entirely toward homology-directed repair, whereas absence of Ligase IV has no detectable impact. Using a reporter assay targeting phytoene desaturase, we demonstrate that Polθ-deficient strains enhance incorporation of repair templates, even when mutations are distant from the cut site. Also, insertion of larger fragments is improved. Finally, disrupting Polθ imposes only a modest fitness cost, highlighting its value for future genome engineering in this species.
Androlaelaps marmosops, a new species of laelapid mite, is described from the pelage of the mouse opossum, Marmosops incanus (Lund, 1840) (Mammalia: Didelphidae), in two areas of Atlantic Forest of Rio de Janeiro State. Measurements and illustrations are included for females only.
Rapid analytical methods are described to control quality of honeys, concerning residues of acaricides applied in hives to prevent Varroa jacobsoni infestation. A liquid-liquid extraction with hexane-propanol-2-ammonia (60 ml:30 ml:0.28%) was used for the simultaneous analysis of coumaphos, bromopropylate, amitraz and fluvalinate. For thymol, one clean up on a solid-phase extraction C18 (500 mg, 6 ml) column was performed; for rotenone, a liquid extraction with dichloromethane was realised. Quantitative recoveries obtained with honey were satisfactory and were superior to 80%. All acaricides are identified by reversed-phase high-performance liquid chromatography with photodiode array detection. Quantification limits obtained were below maximal residue limits when these exist.