Project description:The marine diatom Guinardia delicatula is a cosmopolitan species that dominates seasonal blooms in the English Channel and the North Sea. Several eukaryotic parasites are known to induce the mortality of this key-stone species. Here, we report the isolation and the characterization of the first viruses that infect G. delicatula. Viruses were isolated from the Western English Channel (SOMLIT-ASTAN station) during the late summer bloom decline of G. delicatula. A combination of laboratory approaches revealed that these lytic viruses (GdelRNAV) are small untailed particles of 35-38 nm in diameter that replicated in the host cytoplasm where both unordered particles and crystalline arrays were formed. GdelRNAV displayed a linear single-stranded RNA genome of ~9 kb, including two open reading frames encoding for replication and structural polyproteins. Phylogenetic relationships based on the RNA-dependent-RNA-polymerase gene marker showed that GdelRNAV were new members of the Bacillarnavirus, a monophyletic genus belonging to the order Picornavirales. GdelRNAV were specific to several strains of G. delicatula, they were produced rapidly (< 12h) and in numbers (9.34 x 104 virions per host cell). We recorded a substantial delay (72 h) between virions release and host cell lysis. Our analysis points to variable viral susceptibilities of the host during the early exponential growth phase. Interestingly, we consistently failed to isolate viruses during spring and early summer while G. delicatula developed rapid and massive blooms. While our study suggests that viruses do contribute to the decline of G. delicatula late summer bloom, they may not be the primary mortality agents during the remaining blooms at SOMLIT-ASTAN. Future studies should focus on the relative contribution of the viral and eukaryotic pathogens to the control of Guinardia blooms to understand the fate of these prominent organisms in marine systems.
Project description:Proteomic samples were harvested from different life cycle stages of the invasive pest Lycorma Delicatula, or the Spotted Lanternfly. Adults were captured in the wild while egg and early instar samples were obtained by hatching insects in captivity. Samples were homogenized by bead disruption after percussive homogenization of samples frozen at -80C. Homogenization in 1x S-trap lysis buffer (Protifi, Long Island, NY) was performed in 30s pulses until homogenization appeared complete by visual inspection. The resulting lysate was reduced in DTT and alkylated with iodoacetamide prior to S-Trap mini digestion following vendor protocols. The resulting peptides were analyzed by diaPASEF based proteomics using the default workflow for "short gradient diaPASEF" in TimsControl 4.0. Raw files were processed with a 6 frame translation of the L. delicatula genome sequence and annotated with EggNog Mapper V2 with peptide match and quantification performed with SpectroNaut 18. Please see the associated metadata excel sheet for sample identities.