Production of two highly abundant 2-methyl-branched fatty acids by blooms of the globally significant marine cyanobacteria Trichodesmium erythraeum

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Gosselin, K. M., Nelson, R. K., Spivak, A. C., Sylva, S. P., Van Mooy, B. A. S., Aeppli, C., Sharpless, C. M., O’Neil, G. W., Arrington, E. C., Reddy, C. M., & Valentine, D. L. Production of two highly abundant 2-methyl-branched fatty acids by blooms of the globally significant marine cyanobacteria Trichodesmium erythraeum. ACS Omega, 6(35), (2021): 22803–22810, https://doi.org/10.1021/acsomega.1c03196.The bloom-forming cyanobacteria Trichodesmium contribute up to 30% to the total fixed nitrogen in the global oceans and thereby drive substantial productivity. On an expedition in the Gulf of Mexico, we observed and sampled surface slicks, some of which included dense blooms of Trichodesmium erythraeum. These bloom samples contained abundant and atypical free fatty acids, identified here as 2-methyldecanoic acid and 2-methyldodecanoic acid. The high abundance and unusual branching pattern of these compounds suggest that they may play a specific role in this globally important organism.This work was funded with grants from the National Science Foundation grants OCE-1333148, OCE-1333162, and OCE-1756254 and the Woods Hole Oceanographic Institution (IR&D). GCxGC analysis made possible by WHOI’s Investment in Science Fund

17-β-Estradiol-dependent regulation of somatostatin receptor subtype expression in the 7315b prolactin secreting rat pituitary tumor in vitro and in vivo

In the present study, we have investigated the role of estrogens in the regulation of somatostatin receptor subtype (sst) expression in 7315b PRL- secreting rat pituitary tumor cells in vitro and in vivo. sst were undetectable in freshly dispersed cells of the transplantable 7315b tumor. When 7315b cells were cultured in medium containing 10% FCS, the number of high affinity sst increased with prolonged culture time. However, when the medium was supplemented with 10% horse serum (HS) instead of FCS, no sst were detectable on 7315b cells even after three weeks of culturing. In contrast to HS, FCS contains high E2-levels (HS, 8 pM; FCS, 134 pM). The antiestrogen tamoxifen (0.5 μM) significantly inhibited the sst number to 50.5% of the value of untreated FCS-grown cells, suggesting that E2 stimulates sst expression in 7315b rat pituitary tumor cells. E2 (l0 nM) induced a rapid increase in sst number in HS-grown 7315b cells. Octreotide (1μM) significantly inhibited PRL release and the intracellular PRL concentration of 7315b cells that were cultured in medium supplemented with FCS or with HS + l0 nM E2 but not in HS alone. This indicates that the sst present on these cells are biologically active. RT-PCR analysis revealed that none of the five currently known sst subtypes were present in freshly dispersed 7315b pituitary tumor cells. The expression of sst2- and sst3- messenger RNA (mRNA) was unequivocally correlated to the presence of E2 because these sst subtypes were detected only in cells that were cultured for7 and 14 days in medium supplemented with FCS or with HS + 10 nM E2. sst1, sst4 and sst5 messenger RNA could not be detected. The 7315b tumor itself synthesizes and secretes huge amounts of PRL. The high PRL levels in tumor-bearing rats inhibit the ovarian E2-production. No detectable E2 levels could be measured in the serum of 7315b tumor-bearing rats. The sc administration of 20 μg/day E2-benzoate normalized the circulating E2 levels in 7315b tumor- bearing rats. Moreover, E2-treatment indeed induced sst expression in vivo as shown by ligand binding studies using membrane homogenates and [125I- Tyr3]-octreotide as radioligand and by autoradiography on tissue sections. In agreement with the in vitro studies, the expression of the sst2 subtype was established by RT-PCR analysis in 7315b tumors of E2-treated rats. However, in contrast to the in vitro studies. E2-treatment did not effectuate the expression of the sst3 subtype, suggesting that the in vitro stimulus of E2 is stronger. In conclusion: 1) sst2 and sst3 expression in the 7315b rat prolactinoma model is primarily dependent upon the presence of estrogens; 2) the antihormonal action of octreotide in 7315b tumor cells in vitro is mediated via the sst2 and/or sst3 subtypes; 3) the absence of sst expression in vivo can be explained by the hormonal environment of the 7315b tumor cells. The 7315b tumor cells in vivo may down-regulate their own receptor status via their host, because of the ensuing hyperprolactinemia results in a hypo-estrogenic state.</p

Excited States in 52Fe and the Origin of the Yrast Trap at I=12+

Excited states in 52Fe have been determined up to spin 10\hbar in the reaction 28Si + 28Si at 115 MeV by using \gamma-ray spectroscopy methods at the GASP array. The excitation energy of the yrast 10+ state has been determined to be 7.381 MeV, almost 0.5 MeV above the well known \beta+-decaying yrast 12+ state, definitely confirming the nature of its isomeric character. The mean lifetimes of the states have been measured by using the Doppler Shift Attenuation method. The experimental data are compared with spherical shell model calculations in the full pf-shell.Comment: 9 pages, RevTeX, 7 figures include

Metabolite composition of sinking particles differs from surface suspended particles across a latitudinal transect in the South Atlantic

© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in [citation], doi:[doi]. Johnson, W. M., Longnecker, K., Soule, M. C. K., Arnold, W. A., Bhatia, M. P., Hallam, S. J., Van Mooy, B. A. S., & Kujawinski, E. B. Metabolite composition of sinking particles differs from surface suspended particles across a latitudinal transect in the South Atlantic. Limnology and Oceanography, (2019), doi:10.1002/lno.11255.Marine sinking particles transport carbon from the surface and bury it in deep‐sea sediments, where it can be sequestered on geologic time scales. The combination of the surface ocean food web that produces these particles and the particle‐associated microbial community that degrades them creates a complex set of variables that control organic matter cycling. We use targeted metabolomics to characterize a suite of small biomolecules, or metabolites, in sinking particles and compare their metabolite composition to that of the suspended particles in the euphotic zone from which they are likely derived. These samples were collected in the South Atlantic subtropical gyre, as well as in the equatorial Atlantic region and the Amazon River plume. The composition of targeted metabolites in the sinking particles was relatively similar throughout the transect, despite the distinct oceanic regions in which they were generated. Metabolites possibly derived from the degradation of nucleic acids and lipids, such as xanthine and glycine betaine, were an increased mole fraction of the targeted metabolites in the sinking particles relative to surface suspended particles, while algal‐derived metabolites like the osmolyte dimethylsulfoniopropionate were a smaller fraction of the observed metabolites on the sinking particles. These compositional changes are shaped both by the removal of metabolites associated with detritus delivered from the surface ocean and by production of metabolites by the sinking particle‐associated microbial communities. Furthermore, they provide a basis for examining the types and quantities of metabolites that may be delivered to the deep sea by sinking particles.The authors would like to thank the captain and crew of the R/V Knorr and R/V Atlantic Explorer, as well as Justin Ossolinski, Catherine Carmichael, and Sean Sylva for helping to make this data set possible. Special thanks to Colleen Durkin for sharing her data and providing feedback on the manuscript. Funding for this work came from the National Science Foundation (NSF Grant OCE‐1154320 to EBK and KL) and a WHOI Ocean Ventures Fund award to WMJ. The instruments in the WHOI FT‐MS Facility were purchased with support from the Gordon & Betty Moore Foundation and NSF. Support for WMJ was provided by a National Defense Science and Engineering Fellowship. Sequencing was performed under the auspices of the US Department of Energy (DOE) JGI Community Science Program (CSP) project (CSP 1685) supported by the Office of Science of US DOE Contract DE‐AC02‐ 05CH11231. Additional work related to sample collection and processing was supported by the G. Unger Vetlesen and Ambrose Monell Foundations, the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canadian Institute for Advanced Study (CIFAR), and the Canada Foundation for Innovation through grants awarded to SJH. MPB was supported by a CIFAR Global Scholarship and NSERC postdoctoral fellowship

Dissolved Organic Matter in the Upwelling System off Peru: Imprints of Bacterial Activity and Water Mass Characteristics

Microbial degradation of dissolved organic matter (DOM) contributes to the formation and preservation of oxygen minimum zones (OMZs) in the ocean, but information on the spatial distribution and molecular composition of DOM in OMZ regions is scarce. We quantified molecular components of DOM that is, dissolved amino acids (DAA) and dissolved combined carbohydrates (DCCHO), in the upwelling region off Peru. We found the highest concentrations of DCCHO in fully oxygenated surface waters steeply declining at shallow depth. The highest DAA concentrations were observed close to the surface also, but attenuation of DAA concentration over depth was less pronounced. Compositional changes of DCCHO were strongest within more oxygenated waters. Compositional changes of DAA were also evident under suboxic conditions (<5 µmol O2 kg−1) and indicated bacterial peptide degradation. Moreover, specific free amino acids (alanine and threonine) were enhanced within suboxic waters, pointing to a potential production of dissolved organic nitrogen under suboxic conditions. Our results therewith suggest that deoxygenation supports a spatial decoupling of DCCHO and DAA production and degradation dynamics and give new insights to carbon and nitrogen cycling in the OMZ off Peru

Diabetic patients detected by population-based stepwise screening already have a diabetic cardiovascular risk profile

OBJECTIVE - To describe a population-based two-step screening procedure for type 2 diabetes and to study the cardiovascular risk profile of the patients identified by the screening. RESEARCH DESIGN AND METHODS - The first step of the screening procedure consisted of the Symptom Risk Questionnaire (SRQ), and the second step was a fasting capillary glucose measurement. In subjects with an SRQ score of >6 and a capillary glucose level of >5.5 mmol/l, an oral glucose tolerance test was performed. RESULTS - A total of 11,679 inhabitants of the West-Friesland region of the Netherlands, aged 50-75 years, were invited. Of the inhabitants, 9,169 (78%) responded, and, of those, 417 had previously diagnosed diabetes. The SRQ score was calculated for 7,736 participants, and 3,301 of those had a score of >6. A total of 2,885 subjects (87.3%) attended for capillary glucose measurement. Diagnostic testing was carried out in 509 participants, and we identified 217 diabetic patients. In these patients detected by screening, mean Hb