Regenerated extracellular NH4+ affects the motile chemosensory responses of batch-cultured oxyrrhis marina

Regenerated extracellular NH4+in laboratory batch-cultures of the heterotrophic marine microzooplankter Oxyrrhis marina affects the strength and consistency of chemotaxes elicited by synthetic and biogenic chemoattractants. The ecological relevance of experiments with batch-cultured O. marina and limitations of the microcapillary assay for the study of chemosensory behaviours are discussed.

Nitrogen-deficient microalgae are rich in cell-surface mannose: potential implications for prey biorecognition by phagotrophic protozoa / Microalgas com deficiência de nitrogênio são enriquecidas com manose na superfície celular: potenciais implicações para reconhecimento de presas por protozoários fagotróficos

Flow cytometry was used to quantify the abundance of mannose-linked glycoconjugates on microalgae precultured using low- or high-nitrate media. Nitrogen-deficient microalgae were richer in cell-surface mannose than nitrogen-sufficient. Findings are discussed in view of recent research which reveals mannose-specific 'feeding receptors' assist prey biorecognition by phagotrophic protozoa that ingest microalgae.

Citometria de fluxo foi usada para quantificar a abundância de glicoconjugados com manose em precultivos de microalgas usando meios com baixo e alto teor de nitrato. Microalgas com deficiências de nitrogênio tinham mais manose na superfície celular do que as com nitrogênio suficiente. Resultados são discutidos com base nas pesquisas recentes que revelam receptores específicos para manose que auxiliam no reconhecimento da presa por protozoários fagotróficos que ingerem microalgas.