The nitrogen-fixing bacterium, Nostoc, is a commonly occurring cyanobacterium often found in symbiotic associations. We investigated the potential of cycad cyanobacterial endosymbionts to synthesize microcystin/nodularin. Endosymbiont DNA was screened for the aminotransferase domain of the toxin biosynthesis gene clusters. Five endosymbionts carrying the gene were screened for bioactivity. Extracts of two isolates inhibited protein phosphatase 2A and were further analyzed using electrospray ionization mass spectrometry (ESI-MS)/MS. Nostoc sp. ‘Macrozamia riedlei 65.1’ and Nostoc sp. ‘Macrozamia serpentina 73.1’ both contained nodularin. High performance liquid chromatography (HPLC) HESI-MS/MS analysis confirmed the presence of nodularin at 9.55±2.4 ng μg−1 chlorophyll a in Nostoc sp. ‘Macrozamia riedlei 65.1’ and 12.5±8.4 ng μg−1 Chl a in Nostoc sp. ‘Macrozamia serpentina 73.1’ extracts. Further scans indicated the presence of the rare isoform [L-Har2] nodularin, which contains l-homoarginine instead of l-arginine. Nodularin was also present at 1.34±0.74 ng ml−1 (approximately 3 pmol per g plant ww) in the methanol root extracts of M. riedlei MZ65, while the presence of [L-Har2] nodularin in the roots of M. serpentina MZ73 was suggested by HPLC HESI-MS/MS analysis. The ndaA-B and ndaF genomic regions were sequenced to confirm the presence of the hybrid polyketide/non-ribosomal gene cluster. A seven amino-acid insertion into the NdaA-C1 domain of N. spumigena NSOR10 protein was observed in all endosymbiont-derived sequences, suggesting the transfer of the nda cluster from N. spumigena to terrestrial Nostoc species. This study demonstrates the synthesis of nodularin and [L-Har2] nodularin in a non-Nodularia species and the production of cyanobacterial hepatotoxin by a symbiont in planta.
Pelagic biofoulers such as barnacles or bryozoans settle and raft on natural debris like pumice or seeds. Recent influxes of marine debris into the world's oceans, especially plastic, have increased habitat availability for these biofoulers. Goose barnacles in the genus Lepas are some of the most common biofouling taxa globally, and play an important role in biofouling communities as foundation species. We examined community succession, growth rates and isotopic composition in Lepas and their associated biofouling communities in coastal waters of eastern Australia. Community succession on a fixed surface mooring showed an increase in species diversity over 25 weeks. Using the abundances of L. anserifera, L. anatifera, and the amphipods Caprella danilevskii and Jassa slatteryi, we created an equation to estimate minimum duration at sea. Predators such as the polychaete Amphinome rostrata may influence the biofouling community, as can beach scavengers once floating debris is cast ashore. We report a new maximum growth rate for L. anserifera of 1.45 mm −1 , and our study is the first to report growth rates for any species of Lepas faster than 1 mm day −1 . Lepas were larger on moored floats than on smaller, free-floating drifters. δ 18 O content of Lepas shells was a robust predictor of sea surface temperatures during formation for L. anatifera and L. anserifera. Our findings have important applications for estimating drift duration and trajectories of marine debris.
The first dental proteomic profile of Iron Age individuals (ca. 2000–1000 years B.P.), collected from the site of Long Long Rak rock shelter in northwest Thailand is described. A bias toward the preservation of the positively charged aromatic, and polar amino acids is observed. It is evident that the 212 proteins identified (2 peptide, FDR <1%) comprise a palimpsest of alterations that occurred both ante‐mortem and post‐mortem. Conservation of amino acids within the taphonomically resistant crystalline matrix enabled the identification of both X and Y chromosome linked amelogenin peptides. A novel multiple reaction monitoring method using the sex specific amelogenin protein isoforms is described and indicate the teeth are of male origin. Functional analysis shows an enrichment of pathways associated with metabolic disorders and shows a capacity for harboring these conditions prior to death. Stable isotope analysis using carbon isotopes highlights the strongly C3 based (≈80%) diet of the Long Long Rak cemetery people, which probably comprised rice combined with protein from freshwater fish among other food items. The combination of proteomics and stable isotope analysis provides a complementary strategy for assessing the demography, diet, lifestyle, and possible diseases experienced by ancient populations.
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