skip to main content


Title: Analysis of vitamin B 12 in seawater and marine sediment porewater using ELISA: Vitamin B 12 analysis in seawater using ELISA
Award ID(s):
0752105
NSF-PAR ID:
10023364
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Limnology and Oceanography: Methods
Volume:
9
Issue:
10
ISSN:
1541-5856
Page Range / eLocation ID:
515 to 523
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract

    The cyclopropyl group is of great importance in medicinal chemistry, as it can be leveraged to influence a range of pharmaceutical properties in drug molecules. This report describes a Vitamin B12‐photocatalyzed approach for the cyclopropanation of electron‐deficient alkenes using dichloromethane (CH2Cl2) as the methylene source. The reaction proceeds in good to excellent yields under mild conditions, has excellent functional group compatibility, and is highly chemoselective. The scope could also be extended to the preparation of D2‐cyclopropyl and methyl‐substituted cyclopropyl adducts starting from CD2Cl2and 1,1‐dichloroethane, respectively.

     
    more » « less
  2. Abstract

    The cyclopropyl group is of great importance in medicinal chemistry, as it can be leveraged to influence a range of pharmaceutical properties in drug molecules. This report describes a Vitamin B12‐photocatalyzed approach for the cyclopropanation of electron‐deficient alkenes using dichloromethane (CH2Cl2) as the methylene source. The reaction proceeds in good to excellent yields under mild conditions, has excellent functional group compatibility, and is highly chemoselective. The scope could also be extended to the preparation of D2‐cyclopropyl and methyl‐substituted cyclopropyl adducts starting from CD2Cl2and 1,1‐dichloroethane, respectively.

     
    more » « less
  3. null (Ed.)
  4. Bacterial hopanoid lipids are ubiquitous in the geologic record and serve as biomarkers for reconstructing Earth’s climatic and biogeochemical evolution. Specifically, the abundance of 2-methylhopanoids deposited during Mesozoic ocean anoxic events (OAEs) and other intervals has been interpreted to reflect proliferation of nitrogen-fixing marine cyanobacteria. However, there currently is no conclusive evidence for 2-methylhopanoid production by extant marine cyanobacteria. As an alternative explanation, here we report 2-methylhopanoid production by bacteria of the genusNitrobacter, cosmopolitan nitrite oxidizers that inhabit nutrient-rich freshwater, brackish, and marine environments. The model organismNitrobacter vulgarisproduced only trace amounts of 2-methylhopanoids when grown in minimal medium or with added methionine, the presumed biosynthetic methyl donor. Supplementation of cultures with cobalamin (vitamin B12) increased nitrite oxidation rates and stimulated a 33-fold increase of 2-methylhopanoid abundance, indicating that the biosynthetic reaction mechanism is cobalamin dependent. BecauseNitrobacterspp. cannot synthesize cobalamin, we postulate that they acquire it from organisms inhabiting a shared ecological niche—for example, ammonia-oxidizing archaea. We propose that during nutrient-rich conditions, cobalamin-based mutualism intensifies upper water column nitrification, thus promoting 2-methylhopanoid deposition. In contrast, anoxia underlying oligotrophic surface ocean conditions in restricted basins would prompt shoaling of anaerobic ammonium oxidation, leading to low observed 2-methylhopanoid abundances. The first scenario is consistent with hypotheses of enhanced nutrient loading during OAEs, while the second is consistent with the sedimentary record of Pliocene–Pleistocene Mediterranean sapropel events. We thus hypothesize that nitrogen cycling in the Pliocene–Pleistocene Mediterranean resembled modern, highly stratified basins, whereas no modern analog exists for OAEs.

     
    more » « less