Iron-Catalyzed Polymerization of Isoprene and Other 1,3-Dienes

Chemistry and Chemical Biolog

Iron-Catalyzed 1,4-Hydroboration of 1,3-Dienes

A chemo-, regio-, and stereoselective iron-catalyzed 1,4-hydroboration of dienes that affords γ-disubstituted allylboranes has been developed. 1,4-Hydroboration of 2-substituted dienes forms allylborane products with (E)-trisubstituted double bonds exclusively.Chemistry and Chemical Biolog

The VCAM1-ApoE pathway directs microglial chemotaxis and alleviates Alzheimer\u27s disease pathology

In Alzheimer\u27s disease (AD), sensome receptor dysfunction impairs microglial danger-associated molecular pattern (DAMP) clearance and exacerbates disease pathology. Although extrinsic signals, including interleukin-33 (IL-33), can restore microglial DAMP clearance, it remains largely unclear how the sensome receptor is regulated and interacts with DAMP during phagocytic clearance. Here, we show that IL-33 induces VCAM1 in microglia, which promotes microglial chemotaxis toward amyloid-beta (Aβ) plaque-associated ApoE, and leads to Aβ clearance. We show that IL-33 stimulates a chemotactic state in microglia, characterized by Aβ-directed migration. Functional screening identified that VCAM1 directs microglial Aβ chemotaxis by sensing Aβ plaque-associated ApoE. Moreover, we found that disrupting VCAM1-ApoE interaction abolishes microglial Aβ chemotaxis, resulting in decreased microglial clearance of Aβ. In patients with AD, higher cerebrospinal fluid levels of soluble VCAM1 were correlated with impaired microglial Aβ chemotaxis. Together, our findings demonstrate that promoting VCAM1-ApoE-dependent microglial functions ameliorates AD pathology

Draft genome sequence of uncultured upland soil cluster gammaproteobacteria gives molecular insights into high-affinity methanotrophy

Aerated soils form the second largest sink for atmospheric CH₄. A nearcomplete genome of uncultured upland soil cluster Gammaproteobacteria that oxidize CH₄ at 2.5 ppmv was obtained from incubated Antarctic mineral cryosols. This first genome of high-affinity methanotrophs can help resolve the mysteries about their phylogenetic affiliation and metabolic potential

Erratum for Edwards et al., “Draft genome sequence of uncultured upland soil cluster Gammaproteobacteria gives molecular insights into high-affinity methanotrophy”

Erratum for Edwards et al., “Draft Genome Sequence of Uncultured Upland Soil Cluster Gammaproteobacteria Gives Molecular Insights into High-Affinity Methanotrophy”

Plasma Apolipoprotein B-48, Hepatic Apolipoprotein B mRNA Editing and Apolipoprotein B mRNA Editing Catalytic Subunit-1 mRNA Levels Are Altered in Zinc-Deficient Rats

Apolipoprotein B (apoB) exists as two major isoforms and serves as an obligatory component of lipid-rich plasma lipoprotein particles. Apolipoprotein B mRNA editing is a zinc-dependent, site-specific cytidine deamination that determines whether the apoB-100 or apoB-48 isoform is synthesized. The objective of this work was to examine whether dietary zinc levels affect apoB mRNA editing in vivo. Adult male Sprague-Dawley rats were randomly assigned to zinc-deficient (ZD, Ͻ0.5 mg Zn/kg diet), zinc-adequate (ZA, 30 mg Zn/kg diet) or zincreplenished (ZDA, ZD rats fed the ZA diet for last 2 d) dietary groups for 18 d. The ratio of plasma apolipoprotein B-48 (apoB-48) to total apoB was significantly lower in zinc-deficient compared with zinc-adequate rats. Primer extension analysis indicated a modest but significant reduction in hepatic apoB mRNA editing in ZD rats compared with that of the ZA group. In ZDA rats, hepatic apoB mRNA editing and the percentage of plasma apoB-48 to total apoB were not different from ZA rats. The mRNA abundance of hepatic apobec-1 (apoB mRNA editing catalytic subunit 1) was significantly lower in ZD and ZDA rats than in ZA rats. In summary, the plasma ratio of apoB-48 to total apoB protein as well as hepatic apoB mRNA editing and hepatic apobec-1 mRNA levels were reduced in rats consuming a zinc-deficient diet. These data suggest that one or more components of apoB metabolism may be influenced by dietary zinc status. J. Nutr. 129: 1855–1861, 1999

Regulation of Intestinal Apolipoprotein B mRNA Editing Levels by a Zinc-Deficient Diet and cDNA Cloning of Editing Protein in Hamsters

This study was conducted to investigate the influence of dietary zinc on intestinal apoB mRNA editing in hamsters. Apolipoprotein B-48 (apoB-48) is synthesized from the same gene as apoB-100 by a post-transcriptional, site-specific cytidine deamination, a process known as apoB mRNA editing. A cDNA encoding the hamster apoB mRNA editing enzyme was obtained by reverse transcriptase-polymerase chain reaction (RT-PCR) and the deduced amino acid sequence was found to possess high amino acid sequence identity to apoB mRNA editing enzymes from several other species. Editing activity was detected in the small intestine and colon but, like humans, none was detected in the liver. Analysis by RT-PCR indicated that the small intestine possessed the highest expression of editing enzyme mRNA abundance, whereas both liver and small intestine expressed relatively high levels of apoB mRNA. The influence of dietary zinc on intestinal apoB mRNA editing levels was examined in Golden Syrian hamsters (7 wk old) assigned to one of the following three dietary treatments: Zn-adequate (ZA, 30 mg Zn/kg diet), Zn-deficient (ZD, Ͻ0.5 mg Zn/kg diet), or Zn-replenished (ZDA, ZD hamsters receiving ZA diet for last 2 d) for 7 wk. Hamsters consuming the ZD diet had modestly but significantly lower intestinal editing activity than ZA hamsters. Intestinal editing activity in the ZDA group was not different from that of ZA hamsters. Data derived from these studies contribute to the understanding of lipoprotein metabolism in hamsters, a suitable model for the study of atherosclerosis. J. Nutr. 130: 2166 –2173, 2000

Characterizing temporary hydrological regimes at a European scale

Monthly duration curves have been constructed from climate data across Europe to help address the relative frequency of ecologically critical low flow stages in temporary rivers, when flow persists only in disconnected pools in the river bed. The hydrological model is 5 based on a partitioning of precipitation to estimate water available for evapotranspiration and plant growth and for residual runoff. The duration curve for monthly flows has then been analysed to give an estimate of bankfull flow based on recurrence interval. The corresponding frequency for pools is then based on the ratio of bank full discharge to pool flow, arguing from observed ratios of cross-sectional areas at flood 10 and low flows to estimate pool flow as 0.1% of bankfull flow, and so estimate the frequency of the pool conditions that constrain survival of river-dwelling arthropods and fish. The methodology has been applied across Europe at 15 km resolution, and can equally be applied under future climatic scenarios