The crystalline style of Choromytilus meridionalis Krauss contains a bacteriolytic enzyme capable of lysing the majorlty of free-living bacteria in the adjacent water column. Estimates of the carbon-to-nitrogen ratio (3.7:l) of free-living bacteria, and of the filtration capabilities of the mussels. indicate that bacteria could meet the nitrogen requirements of the mussels. The bacteriolytic agent in the style is subject to considerable adaptive changes in activity, correlated with water temperature.Water temperatures < 10°C are associated with ~nduction of the bacteriolytic agent. During upwelling, cold water depleted in particulate matter but containing significant numbers of bacteria occurs commonly amongst the kelp beds. It is suggested that low water temperature (or an associated environmental parameter) results in stimulation of bacteriolysis. This in turn permits efficient utilisation by the mussel of free-living bacteria which compensate for the depletion of phytoplankton available in the water column.
The National Institutes of Health (NIH) issued a new policy that requires a single institutional review board (IRB) of record be used for all protocols funded by the NIH that are carried out at more than one site in the United States, effective January 2018. This policy affects several hundred clinical trials opened annually across the NIH. Limited data exist to compare the use of a single IRB to that of multiple local IRBs, so some institutions are resistant to or distrustful of single IRBs. Since 2001, the National Cancer Institute (NCI) has funded a central IRB (CIRB) that provides human patient reviews for its extensive national cancer clinical trials program. This paper presents data to show the adoption, efficiencies gained, and satisfaction of the CIRB among NCI trial networks and reviews key lessons gleaned from 16 years of experience that may be informative for others charged with implementation of the new NIH single-IRB policy.
ABSTRACT. Environmental variables, and summer and winter particulate concentrations in the water column of a kelp bed in an upwelling region on the western Cape coast of South Africa, were measured daily to assess short-term fluctuations. There were significant differences between the summer and winter upwelling index, water temperature and wave height. Summer part~culate carbon and nitrogen concentrations of 533 11g 1-' and 66 pg 1-' respectively were lower than winter levels of 764 pg C 1-' and 79 pg N 1-'. However, summer upwelling events did not reduce particulate carbon and nitrogen to the very low levels that might be expected from previous studies of chlorophyll concentrations in the kelp bed. Large waves resulted in C:N ratios that were significantly hlgher in winter than in summer @ < 0.01), and during continuous winter downwelling, a large proportion of the particulate material in the water column was of macrophyte rather than phytoplankton origin. In summer the carbon and nitrogen load was most highly correlated with temperature, while wind and wave size were the most important factors affecting particulate concentrations in winter. Mean particulate organic concentrations were 380 big C I-' and 43 pg N I-' and these compare weU with concentrations of 301 k~g C 1-' and 4 1 pg N 1-' estimated from previous primary production studies. The estimated carbon demands of Choromytilus meridjonalis and Aulacomya ater, 2 mussels that commonly occur in kelp beds on the west coast, could be met in winter and summer by the particulate organic component in the kelp bed water column. Particulate nitrogen resources probably meet most of the nitrogen requirements of the 2 mussels.
Bacteria in kelp-related ecosystems on the west coast of South Africa were isolated using random sampling techniques. The percentage of bacteria forming colonies on solid media was determined. The population composition in 4 adjacent habitats was determined by morphological and physiological criteria. These data were analysed by cluster analysis using the Bray-Curtis measure of similarity. Isolates from inshore waters were able to ferment a wide range of kelp-derived products, whereas offshore isolates had a more restricted spectrum of fermentable substrates. The similarity analysis indicates that bacteria isolated from the 4 adjacent hab~tats are essentially different. It is suggested that bacterial assemblages in adjacent habitats segregate into discrete populations in response to physical, chemical and biological factors.
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