Clay minerals of the Morrison(?) Formation of Central Utah

Twenty-three mudstone samples, seventeen from the Morrison(?) Formation of central Utah, three from the Morrison Formation and three from the Cedar Mountain Formation of the Colorado Plateau, were collected during the summer of 1983. The whole fraction of each sample was X-rayed to identify the major mineral constituents. All of the samples contained quartz, and most contained calcite. Dolomite, feldspar, and either hematite or goethite were present in small amounts in many. Gypsum was present in a few. Traces of halite and ilmenite were present in one sample each. Oriented mounts of the clay fraction of each sample were X-rayed twice, once after air-drying, and once after solvation in ethylene glycol, to determine the clay mineral constituents. All but one of the samples contained smectite or interstratified smectite-illite as the predominant clay constituent. One sample contained illite as the predominant clay constituent. Kaolinite and discrete illite were present in several samples. The interstratified clays in the mudstones of the Morrison(?) of central Utah and the Morrison of the Colorado Plateau generally contained a higher proportion of smectite than the interstratified clays in the mudstones of the Cedar Mountain. Smectites are frequently bentonite clays, indicating that the clay-sized sediment in the mudstones of the Morrison(?) may have been derived from altered volcanic detritus. The Morrison(?) mudstones studied by Chapman (1981) and Ross (1982) cannot be correlated to the mudstone layers sampled for this study by using the clay mineral constituents in the samples, because the differences in smectite to illite ratios in the interstratified clays occurring in these mudstones may be accounted for by differing stages of alteration of smectite to illite.No embarg

A Site Study of Soil Charactersistics and Soil Gas Radon in Rochester, Minnesota

Uncopyrighted report. Acknowledgement of the Minnesota Geological Survey and CURA would be appreciated is this material is used.In regional surveys, indoor radon is usually the parameter of interest, but occasionally soil gas radon at depths of 1 meter or less is also measured. At statewide scales, even limited data sets can be used to infer relationships between geology and soil gas or indoor radon. However, predicting the radon potential of a single house or even an area the size of a neighborhood is more difficult As the size of a surveyed area decreases, site-specific variables become more significant. During 1990 we completed a study of two residential neighborhoods within 7 kilometers of each other near Rochester, Minnesota. Eight holes were augered into glacial sediments to maximum depths of 4.5 meters and samples collected for grain-size analysis, measurement of radon parent/daughter nuclides and radon emanation. A total of sixty-five homes in the areas were provided with two alpha-track registration detectors for indoor monitoring between September 1988 and September 1989. Positive correlations were observed between the average soil radon, the average indoor radon, and the precursor/daughter radionuclides. The study area with the most topographic relief also had the highest radionuclide contents, the most variability with depth, and some variation with time and soil moisture; these results were not observed at the low-relief site. The type of study described would best be applied to site-specific preconstruction screening, rather than to predicting radon in existing structures.Minnesota Geological Survey, Olmsted County Health Department, USDA Soil Conservation Service, Rochester, Minnesota, Center for Urban and Regional Affairs, University of Minnesota, Minneapolis

Site Study of Soil Characteristics and Soil Gas Radon in Rochester, Minnesota.

Two residential neighborhoods were studied in 1990 to compare radon in the soil with indoor radon levels in sixty-five homes. Positive correlations were found. The topographically highest area also had the highest radon levels in soil and in homes. This type of study could be used to predict indoor radon problems before construction of homes is begun.Partial funding provided by the Center for Urban and Regional Affairs, University of Minnesota

Caveolins/caveolae protect adipocytes from fatty acid-mediated lipotoxicity

Mice and humans lacking functional caveolae are dyslipidemic and have reduced fat stores and smaller fat cells. To test the role of caveolins/caveolae in maintaining lipid stores and adipocyte integrity, we compared lipolysis in caveolin-1 (Cav1)-null fat cells to that in cells reconstituted for caveolae by caveolin-1 re-expression. We find that the Cav1-null cells have a modestly enhanced rate of lipolysis and reduced cellular integrity compared with reconstituted cells as determined by the release of lipid metabolites and lactic dehydrogenase, respectively, into the media. There are no apparent differences in the levels of lipolytic enzymes or hormonally stimulated phosphorylation events in the two cell lines. In addition, acute fasting, which dramatically raises circulating fatty acid levels in vivo, causes a significant upregulation of caveolar protein constituents. These results are consistent with the hypothesis that caveolae protect fat cells from the lipotoxic effects of elevated levels fatty acids, which are weak detergents at physiological pH, by virtue of the property of caveolae to form detergentresistant membrane domains

Acyl-CoA synthetase 3 promotes lipid droplet biogenesis in ER microdomains

Control of lipid droplet (LD) nucleation and copy number are critical, yet poorly understood, processes. We use model peptides that shift from the endoplasmic reticulum (ER) to LDs in response to fatty acids to characterize the initial steps of LD formation occurring in lipid-starved cells. Initially, arriving lipids are rapidly packed in LDs that are resistant to starvation (pre-LDs). Pre-LDs are restricted ER microdomains with a stable core of neutral lipids. Subsequently, a first round of “emerging” LDs is nucleated, providing additional lipid storage capacity. Finally, in proportion to lipid concentration, new rounds of LDs progressively assemble. Confocal microscopy and electron tomography suggest that emerging LDs are nucleated in a limited number of ER microdomains after a synchronized stepwise process of protein gathering, lipid packaging, and recognition by Plin3 and Plin2. A comparative analysis demonstrates that the acyl-CoA synthetase 3 is recruited early to the assembly sites, where it is required for efficient LD nucleation and lipid storag

Structural Insights into Triglyceride Storage Mediated by Fat Storage-Inducing Transmembrane (FIT) Protein 2

Fat storage-Inducing Transmembrane proteins 1 & 2 (FIT1/FITM1 and FIT2/FITM2) belong to a unique family of evolutionarily conserved proteins localized to the endoplasmic reticulum that are involved in triglyceride lipid droplet formation. FIT proteins have been shown to mediate the partitioning of cellular triglyceride into lipid droplets, but not triglyceride biosynthesis. FIT proteins do not share primary sequence homology with known proteins and no structural information is available to inform on the mechanism by which FIT proteins function. Here, we present the experimentally-solved topological models for FIT1 and FIT2 using N-glycosylation site mapping and indirect immunofluorescence techniques. These methods indicate that both proteins have six-transmembrane-domains with both N- and C-termini localized to the cytosol. Utilizing this model for structure-function analysis, we identified and characterized a gain-of-function mutant of FIT2 (FLL(157-9)AAA) in transmembrane domain 4 that markedly augmented the total number and mean size of lipid droplets. Using limited-trypsin proteolysis we determined that the FLL(157-9)AAA mutant has enhanced trypsin cleavage at K86 relative to wild-type FIT2, indicating a conformational change. Taken together, these studies indicate that FIT2 is a 6 transmembrane domain-containing protein whose conformation likely regulates its activity in mediating lipid droplet formation

Extramitochondrial OPA1 and adrenocortical function

We have previously described that silencing of the mitochondrial protein OPA1 enhances mitochondrial 27 Ca2+ signaling and aldosterone production in H295R adrenocortical cells. Since extramitochondrial OPA1 28 (emOPA1) was reported to facilitate cAMP-induced lipolysis, we hypothesized that emOPA1, via the 29 enhanced hydrolysis of cholesterol esters, augments aldosterone production in H295R cells. A few 30 OPA1 immunopositive spots were detected in �40% of the cells. In cell fractionation studies OPA1/COX 31 IV (mitochondrial marker) ratio in the post-mitochondrial fractions was an order of magnitude higher 32 than that in the mitochondrial fraction. The ratio of long to short OPA1 isoforms was lower in post-mito- 33 chondrial than in mitochondrial fractions. Knockdown of OPA1 failed to reduce db-cAMP-induced phos- 34 phorylation of hormone-sensitive lipase (HSL), Ca2+ signaling and aldosterone secretion. In conclusion, 35 OPA1 could be detected in the post-mitochondrial fractions, nevertheless, OPA1 did not interfere with 36 the cAMP – PKA – HSL mediated activation of aldosterone secretio

TIP47 functions in the biogenesis of lipid droplets

TIP47 (tail-interacting protein of 47 kD) was characterized as a cargo selection device for mannose 6-phosphate receptors (MPRs), directing their transport from endosomes to the trans-Golgi network. In contrast, our current analysis shows that cytosolic TIP47 is not recruited to organelles of the biosynthetic and endocytic pathways. Knockdown of TIP47 expression had no effect on MPR distribution or trafficking and did not affect lysosomal enzyme sorting. Therefore, our data argue against a function of TIP47 as a sorting device. Instead, TIP47 is recruited to lipid droplets (LDs) by an amino-terminal sequence comprising 11-mer repeats. We show that TIP47 has apolipoprotein-like properties and reorganizes liposomes into small lipid discs. Suppression of TIP47 blocked LD maturation and decreased the incorporation of triacylglycerol into LDs. We conclude that TIP47 functions in the biogenesis of LDs