RESUMEN
Variations in toxicity of the benthic dinoflagellate Ostreopsis Schmidt 1901 have been attributed to specific molecular clades, biogeography of isolated strains, and the associated bacterial community. Here, we attempted to better understand the biodiversity and the basic biology influencing toxin production of Ostreopsis. Nine clonal cultures were established from Okinawa, Japan, and identified using phylogenetic analysis of the ITS-5.8S rRNA and 28S rRNA genes. Morphological analysis suggests that the apical pore complex L/W ratio could be a feature for differentiating Ostreopsis sp. 2 from the O. ovata species complex. We analyzed the toxicity and bacterial communities using liquid chromatography-mass spectrometry, and PCR-free metagenomic sequencing. Ovatoxin was detected in three of the seven strains of O. cf. ovata extracts, highlighting intraspecies variation in toxin production. Additionally, two new potential analogs of ovatoxin-a and ostreocin-A were identified. Commonly associated bacteria clades of Ostreopsis were identified from the established cultures. While some of these bacteria groups may be common to Ostreopsis (Rhodobacterales, Flavobacteria-Sphingobacteria, and Enterobacterales), it was not clear from our analysis if any one or more of these plays a role in toxin biosynthesis. Further examination of biosynthetic pathways in metagenomic data and additional experiments isolating specific bacteria from Ostreopsis would aid these efforts.
Asunto(s)
Dinoflagelados , Japón , Islas del Pacífico , Filogenia , Dinoflagelados/genética , Dinoflagelados/metabolismo , BacteriasRESUMEN
The relative apportionment of hydrocarbons (HCs) coming from mobile, fixed, and other sources (not correlated either to carbon monoxide [CO] or sulfur dioxide [SO2] emissions as solvent evaporation and biogenic sources) is calculated as previously proposed by Riveros et al.1 through the linear approximation [HC]tol = [HC]0 + m1 [CO] + m2 [SO2], where m1 and m2 are fitted constants. The obtained apportionment with air samples taken in 1993 is consistent with the earlier published apportionment with air samples taken in 1992, validating the previous procedure. This analysis suggests that 75% of HC originate from mobile sources, 5-18% from fixed sources, and 7-20% from other sources (mainly solvents and bio-genic sources). A similar analysis was employed to estimate the relative contribution of HCs and nitric oxides (NO2) to ozone (O3) formation, the most important air pollutant in Mexico City. In this way, through a local lineation of O3 isopleths, simultaneous measurements of HC and NO2 in the atmosphere were fitted to the equation-[O3]peak = [O3]0 + ma [HC] + mb [NO2]-to predict O3 peak. With these data, the adjusted parameters show that NO2, not HC as was proposed previously, is the most important contributor to O3 formation.