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The marine cyanobacterium Trichodesmium is ubiquitous in tropical and subtropical seas and is an important contributor to global N and C cycling. We sought to characterize metabolic uptake patterns in individual Trichodesmium IMS-101 cells by quantitatively imaging [sup.13]C and [sup.15]N uptake with high-resolution secondary ion mass spectrometry (NanoSIMS). Trichodesmium fix both C[O.sub.2] and [N.sub.2] concurrently during the day and are, thus, faced with a balancing act: the [O.sub.2] evolved during photosynthesis inhibits nitrogenase, the key enzyme in [N.sub.2] fixation. After performing correlated transmission electron microscopy (TEM) and NanoSIMS analysis on trichome thin-sections, we observed transient inclusion of [sup.15]N and [sup.13]C into discrete subcellular bodies identified as cyanophycin granules. We speculate that Trichodesmium uses these dynamic storage bodies to uncouple C[O.sub.2] and [N.sub.2] fixation from overall growth dynamics. We also directly quantified both C[O.sub.2] and [N.sub.2] fixation at the single cell level using NanoSlMS imaging of whole cells in multiple trichomes. Our results indicate maximal C[O.sub.2] fixation rates in the morning, compared with maximal [N.sub.2] fixation rates in the afternoon, bolstering the argument that segregation of C[O.sub.2] and [N.sub.2] fixation in Trichodesmium is regulated in part by temporal factors. Spatial separation of [N.sub.2] and C[O.sub.2] fixation may also have a role in metabolic segregation in Trichodesmium. Our approach in combining stable isotope labeling with NanoSIMS and TEM imaging can be extended to other physiologically relevant elements and processes in other important microbial systems. NanoSIMS | stable isotope labeling | cyanophycin

Deep-sea corals are found on hard substrates on seamounts and continental margins worldwide at depths of 300 to [approximately equal to] 3,000 m. Deep-sea coral communities are hotspots of deep ocean biomass and biodiversity, providing critical habitat for fish and invertebrates. Newly applied radiocarbon age dates from the deep water proteinaceous corals Gerardia sp. and Leiopathes sp. show that radial growth rates are as low as 4 to 35 [micro]m [year.sup.-1] and that individual colony Longevities are on the order of thousands of years. The longest-lived Gerardia sp. and Leiopathes sp. specimens were 2,742 years and 4,265 years, respectively. The management and conservation of deep-sea coral communities is challenged by their commercial harvest for the jewelry trade and damage caused by deep-water fishing practices. In light of their unusual longevity, a better understanding of deep-sea coral ecology and their interrelationships with associated benthic communities is needed to inform coherent international conservation strategies for these important deep-sea habitat-forming species. age and growth rate | Gerardia sp. | Leiopathes sp. | radiocarbon | stable isotopes

Recent theories for glacial-interglacial climate transitions call on millennial climate perturbations that purged the deep sea of sequestered carbon dioxide via a "bipolar ventilation seesaw." However, the viability of this hypothesis has been contested, and robust evidence in its support is lacking. Here we present a record of North Atlantic deep-water radiocarbon ventilation, which we compare with similar data from the Southern Ocean. A striking coherence in ventilation changes is found, with extremely high ventilation ages prevailing across the deep Atlantic during the last glacial period. The data also reveal two reversals in the ventilation gradient between the deep North Atlantic and Southern Ocean during Heinrich Stadial 1 and the Younger Dryas. These coincided with periods of sustained atmospheric CO2 rise and appear to have been driven by enhanced ocean-atmosphere exchange, primarily in the Southern Ocean. These results confirm the operation of a bipolar ventilation seesaw during deglaciation and underline the contribution of abrupt regional climate anomalies to longer-term global climate transitions. [ABSTRACT FROM AUTHOR]