THE ACTION OF DIMETHYLSULPHIDE IN THE ACTIVATION PROCESS OF ZOOSPORIC MARINE PARASITES TREBALL DE FI DE GRAU MARÍA ANA FERNÁNDEZ JANÉ TUTORS: ESTHER GARCÉS (ICM) i JAVIER ROMERO (UB) GRAU DE CIÈNCIES DEL MAR UNIVERSITAT DE BARCELONA INSTITUT DE CIÈNCIES DEL MAR (ICM-CSIC) Research Group: Littoral Biological Processes September 2020 The action of dimethylsulphide in the activation process of zoosporic marine parasites INDEX INDEX ....................................................................................................................................... 2 SCIENTIFIC SUMMARY ............................................................................................................... 4 DIVULGATIVE SUMMARY .......................................................................................................... 5 SETBACK OF CORONAVIRUS PANDEMIC .................................................................................... 7 INTRODUCTION ........................................................................................................................ 8 OBJECTIVES ............................................................................................................................. 12 METHODOLOGY ...................................................................................................................... 12 SPORANGIA CULTIVATION ................................................................................................... 12 CALCULATION OF DMS ........................................................................................................ 13 EXUDATES ........................................................................................................................... 13 EXPERIMENTS ..................................................................................................................... 14 DATA ANALYSIS ................................................................................................................... 15 STATISTICS .......................................................................................................................... 15 RESULTS .................................................................................................................................. 17 Parvilucifera corolla ............................................................................................................ 17 DMS ................................................................................................................................ 17 EXUDATES ....................................................................................................................... 17 Perkinsea sp.1 ..................................................................................................................... 18 DMS ................................................................................................................................ 18 Parvilucifera sinerae ............................................................................................................ 20 Comparison between species .............................................................................................. 21 Comparison of exudates...................................................................................................... 22 DISCUSSION ............................................................................................................................ 24 DMS .................................................................................................................................... 24 Generalist trigger ............................................................................................................ 24 Comparison of the different parasite response ................................................................ 25 EXUDATES ........................................................................................................................... 25 CONCLUSION .......................................................................................................................... 27 ACKNOWLEDGMENT ............................................................................................................... 28 BIBLIOGRAPHY ........................................................................................................................ 29 2 The action of dimethylsulphide in the activation process of zoosporic marine parasites ANNEXES ................................................................................................................................ 33 3 The action of dimethylsulphide in the activation process of zoosporic marine parasites SCIENTIFIC SUMMARY Harmful algal blooms (HABs) are a topic of concern due to their impacts on the environment and society. These events are controlled by different factors, abiotic and biotic. Parasitism is a biotic factor that controls these blooms and helps to return to the non-bloom conditions. Among the group of marine parasites, Perkinsozoa members represent a major ecological and economical threat because of their invasive, pathogenic, and high phenotypic plasticity. This group of parasites has a similar life cycle, which infects a host cell and after the development into a sporangium, the new parasites get out of it and will infect new hosts. However, before the infection parasites remain in a dormant stage, the sporangium, until a trigger activates them. One of the main triggers was demonstrated to be DMS (dimethylsulphide) in Parvilucifera sinerae. DMS is an organic sulphur compound produced by phytoplankton that has been demonstrated to have a role in chemical ecology. The objective of this project was to determine if this is a general in the family of Perkinsidae. We also tested if zooplankton exudates affect parasite activation due to its interaction as a competitor of the same prey. With laboratory experiments, we studied DMS triggering in two species, Parvilucifera corolla and Perkinsea sp1. With this new data, we found that this is a general mechanism. The species used showed a significant activation when DMS was added. The results also indicated that the process of activation differs between the different species used. The time required and the percentage of activation were species-specific, although with a similar trend. Zooplankton exudates did show a parasite activation similar to the low DMS producer phytoplankton exudates. However, more research is needed in this field. Les proliferacions d’algues tòxiques són un tema de preocupació a causa dels seus impactes al medi ambient i a la societat. Aquests esdeveniments estan controlats per diversos factors abiòtics i biòtics. El parasitisme és un factor biòtic que controla aquestes proliferacions i ajuda a tornar a les condicions de no proliferació. Dins dels paràsits marins, els membres de Perkinsozoa representen una amenaça ecològica i econòmica a causa de la seva invasivitat, patogènia i alta plasticitat fenotípica. Aquests paràsits presenten un cicle de vida similar, en el qual infecten a l’hoste i, després de desenvolupar-se en un esporangi, els nous paràsits surten i infecten a nous hostes. Tot i així, abans de la infecció els paràsits romanen en un estat inactiu, l’esporangi, abans que un factor desencadeni l’activació. Un d’aquests factors va ser demostrat i és el DMS (dimetilsulfur) en Parvilucifera sinerae. El DMS és un compost orgànic de sofre produït pel fitoplàncton que s’ha demostrat que té un rol en l’ecologia química. L’objectiu d’aquest projecte és determinar si aquest mecanisme és general de la família Perkinsidae. També es va testar si els exhudats de zooplàncton produeixen efectes en l’activació dels paràsits a causa de la seva interacció com a competidors sobre una mateixa presa. Amb experiments de laboratori vam estudiar el DMS amb altres dues espècies, Parvilucifera corolla i Perkinsea sp1. Amb les noves vam trobar que és un mecanisme general. Les espècies utilitzades van mostrar una activació significant amb el DMS. Els resultats també van indicar que el procés d’activació no és igual a totes les especies. El temps i el percentatge d’activació diferien, tot i seguir una mateixa tendència. Els exhudats de zooplàncton van mostrar una activació dels paràsits similar a la dels exhudats de fitoplàncton poc productor de DMS. Tot i així, més investigació és necessària. 4 The action of dimethylsulphide in the activation process of zoosporic marine parasites DIVULGATIVE SUMMARY Phytoplankton is the base of the production in the ocean. However, due to biological, chemical, and physical factors, there are events called Harmful Algal Blooms (HABs) when the phytoplankton grows until they reach numbers above the normal range of values. These events are noxious and toxic, not only for human health but also for the wild animals. These events are controlled by biological and physical factors. Biologically there are some factors, like the predators of these organisms and the parasites. Nowadays, the problem of HABs seems to become more frequent and more intense. Countries spend high amounts of money due to this problem and the health and economic impacts of it. Some authors have proposed to use these natural parasites to stop these events. Nevertheless, more investigation is needed to use them because of the uncertainty of the results. This project is centred on marine parasites infecting dinoflagellates, a group of phytoplankton, that is one of the main groups producing HABs. The parasites have a very