Systematic reviews of animal studies – Report of an international symposium

Objective: The Symposium on Animal Systematic Reviews held 24 May 2022, sought to bring organisations working on animal literature searching and systematic reviews together into the same virtual space for introductions and discussion.Background: Groups working on animal research synthesis are often siloed into preclinical, veterinary, and One Health settings. This symposium sought to define commonalities and differences in methodologies, resources, and philosophies and to discuss future needs.Methods: The 3-hour virtual symposium for veterinarians, researchers, and information specialists began with introductions by panelists from organisations involved in searching the literature for animal studies and conducting systematic reviews. This was followed by a panel discussion and question and answer period.Results: Panelists identified a need to ensure planning and accurate description of primary animal studies as a precursor to quality systematic reviews. They acknowledged and discussed differences in evidence synthesis expectations and tools based on the type of review, the types of studies available on the topic, and the focus on preclinical, veterinary, or One Health topics.Conclusion: The need to increase the speed and quality of evidence reviews, and to automate updates, requires investing in the development of both skilled teams and platforms. The symposium provided a chance to identify existing resources, define challenges, and note gaps unique to systematic reviews of animal studies.Application: This symposium acts as a baseline for ongoing discussions centred on improving the culture and pipeline for evidence syntheses of animal studies that inform decision-making

Evidence for Abscisic Acid Biosynthesis in Cuscuta reflexa, a Parasitic Plant Lacking Neoxanthin1[W][OA]

Abscisic acid (ABA) is a plant hormone found in all higher plants; it plays an important role in seed dormancy, embryo development, and adaptation to environmental stresses, most notably drought. The regulatory step in ABA synthesis is the cleavage reaction of a 9-cis-epoxy-carotenoid catalyzed by the 9-cis-epoxy-carotenoid dioxygenases (NCEDs). The parasitic angiosperm Cuscuta reflexa lacks neoxanthin, one of the common precursors of ABA in all higher plants. Thus, is C. reflexa capable of synthesizing ABA, or does it acquire ABA from its host plants? Stem tips of C. reflexa were cultured in vitro and found to accumulate ABA in the absence of host plants. This demonstrates that this parasitic plant is capable of synthesizing ABA. Dehydration of detached stem tips caused a big rise in ABA content. During dehydration, 18O was incorporated into ABA from 18O2, indicating that ABA was synthesized de novo in C. reflexa. Two NCED genes, CrNCED1 and CrNCED2, were cloned from C. reflexa. Expression of CrNCEDs was up-regulated significantly by dehydration. In vitro enzyme assays with recombinant CrNCED1 protein showed that the protein is able to cleave both 9-cis-violaxanthin and 9′-cis-neoxanthin to give xanthoxin. Thus, despite the absence of neoxanthin in C. reflexa, the biochemical activity of CrNCED1 is similar to that of NCEDs from other higher plants. These results provide evidence for conservation of the ABA biosynthesis pathway among members of the plant kingdom