Oikopleura dioicaculturing made easy: A Low‐Cost facility for an emerging animal model inEvoDevo

Abstract

Summary: The genome sequencing and the development of RNAi knockdown technologies in the urochordate Oikopleura dioica are making this organism an attractive emergent model in the field of EvoDevo. To succeed as a new animal model, however, an organism needs to be easily and affordably cultured in the laboratory. Nowadays, there are only two facilities in the world capable to indefinitely maintain Oikopleura dioica, one in the SARS institute (Bergen, Norway) and the other in the Osaka University (Japan). Here, we describe the setup of a new facility in the University of Barcelona (Spain) in which we have modified previously published husbandry protocols to optimize the weekly production of thousands of embryos and hundreds of mature animals using the minimum amount of space, human resources, and technical equipment. This optimization includes novel protocols of cryopreservation and solid cultures for long-term maintenance of microalgal stocks-Chaetoceros calcitrans, Isochrysis sp., Rhinomonas reticulate, and Synechococcus sp.-needed for Oikopleura dioica feeding. Our culture system maintains partially inbred lines healthy with similar characteristics to wild animals, and it is easily expandable to satisfy on demand the needs of any laboratory that may wish to use Oikopleura dioica as a model organism. genesis 53: 183-193,

Diatom bloom-derived biotoxins cause aberrant development and gene expression in the appendicularian chordate Oikopleura dioica

“…6b). To our knowledge this is the first finding suggesting that C. calcitrans is able to produce toxic secondary metabolites, which indeed is consistent with personal observations during the feeding strategy in our O. dioica facility in which excess of this alga in the diet made O. dioica cultures to decline 41 .…”

“…These species included Skeletonema marinoi (Sm) , which has been characterized by its high content of the PUAs heptadienal and octadienal and the lack of decadienal 5,53 ; Chaetoceros affinis ( Ca ), which produces other oxylipins different from PUAs 8 ; Prorocentrum minimum ( Pm ), a dinoflagellate species used as a negative control that does not produce oxylipins 8 ; and Chaetoceros calcitrans ( Cc ), a diatom included in the diet used to feed O. dioica in our animal facility 41 , but for which the capability to produce PUAs was unknown. First, we studied the dose-response of O. dioica development at different concentrations of S. marinoi extracts (from 5 to 100 μg mL −1 ).…”

“…3), increase the sensitivity of appendicularian development to DD toxicity makes plausible to suggest that adult animals exposed to DD throughout generations may accumulate this biotoxin in their gonads and become, therefore, more vulnerable to its detrimental effects. This possibility might explain the observation that overfeeding O. dioica cultures with the diatom C. calcitrans appears to lead culture declining 41 . Considering the ecological relevance of appendicularians in marine food webs and ocean carbon cycle, future experiments are urged to better understand the threat that oxylipins and other biotoxins can cause on the biology of appendicularians in natural environments.…”

“…41 . Briefly, animals were originally collected in the Mediterranean coast of Barcelona (Catalonia, Spain), and kept in the facility with a life cycle of five days at 19 °C.…”

“…37 ), together with the extraordinary amount of gene losses 36 , make that its functional redundancy is lower than in other animal species (e.g., vertebrates). Some gene losses have led this organism to be considered as an evolutionary knockout that can facilitate the dissection of complex genetic networks 36,38–41 . O. dioica has lost, for instance, the retinaldehyde dehydrogenase Aldh1a and most of the components of the metabolic pathway of retinoic acid (RA) 42 , a signaling molecule that in all other chordates plays a fundamental role in the regulation of embryo development, adult organ homeostasis and gametogenesis 43–45 .…”