To address the biodiversity of the genus Haslea, many phytoplankton sampling campaigns were conducted. Samples were collected from sites along the coasts of all continents and strains characterized. The use of molecular markers has shown that some newly species belong to a group within the genus Navicula, a close relative of Haslea. These Haslea-like diatoms could be accommodated in a new genus, provisionally named Pseudo-haslea.
According to last experimental data, marennine is constituted by a glycosidic backbone to which a chromophore is linked. Work is in progress to understand the linkage between and the spatial disposition of the monosaccharides and to determine the nature of the chromophore.
Regarding photophysiology, the work investigated photoadaptation capacities and photoacclimation strategies, comparing Haslea strains originating from different geographic areas from the Arctic to the Equator. Haslea diatoms rapidly, but transiently, upregulate electron transport following changes in light environment. This is of essential importance for blue biotechnology, for photobioreactor control of biomass yield and possibly marennine or high-value compounds production.
The chemical diversity of isoprenoids and blue pigments produced by different Haslea strains has also been investigated. Transcriptomic together with genomic information was mined for the identification of enzyme candidates for the synthesis of highly branched isoprenoids and the corresponding genes were analyzed using heterologous expression systems for the characterization of bioactivity.
For aquaculture, the possible impact of marennine was studied on a broad panel of marine microorganisms and invertebrates. Different pathogenic bacteria of the genus Vibrio exposed to environmentally relevant concentrations of marennine revealed usually sensitive, being inhibited, more rarely stimulated. Experiments were conducted on embryos or larvae of different marine invertebrates, and challenge tests with pathogen cultures or with infected hosts protected by marennine were realized on Pacific oyster adults, blue mussel larvae and juvenile, American oyster larvae. Marennine demonstrated a significant protective effect at low concentration, but showed toxic effect at high concentration on larvae or transient negative impact on the physiology of adult oysters. These results could limit the conditions of use of marennine on larvae for shellfish aquaculture.
Regarding the formation issue, one of the most valuable impacts of GHaNA relates to the many early stage researchers who made secondments in the consortium hosting institutions. They were trained in the use of new instruments, techniques, databases and programs. They also attended trainings about safety issues, transferable skills, learned foreign languages and participated in social activities to discover the hosting countries. This has boosted their careers, by making them more efficient, mobile across different countries, independent, more organized and experienced researchers.
The project was presented by the different partners involved to high school students visiting the universities, to the non-specialist public during events such as the European researchers nights, during science festivals and radio emissions. Haslea and marennine inspired the artwork of two French filmmakers and a glass sculptor.
