Salt Wash Research Articles

Late Jurassic Tectonism on West Side of Colorado Plateau, Utah and Arizona: ABSTRACT

Detailed sedimentologic studies in south-central Utah and north-central Arizona indicate that several major basins and uplifts as well as many smaller folds within them were actively growing during deposition of the Salt Wash Member of the Morrison Formation. The region lies outside that part of the Colorado Plateau underlain by thick Pennsylvanian halite deposits so the structures are not related to salt deformation. Tectonic activity in the region is inferred from several types of sedimentologic features which include thickness variations, facies distribution, cross-bedding parameters, and bedding ratios. Distribution of the various features studied indicates the Emery, Circle Cliffs, Echo Cliffs-Kaibab, Cow Springs, and Monument uplifts, as well as the Henry and Kaipar wits basins, were active during the Late Jurassic. In addition, several anticlines and synclines that were active at the same time can be delineated in or near the Henry and Kaiparowits basins. The apparent absence of local angular unconformities in the Salt Wash near the positive structures suggests that most of the tectonic movements were the result of differential subsidence rather than uplift of the positive structures. It could not be determined if the San Rafael swell near the Emery uplift was active during Late Jurassic time. Also, the relationships are not entirely conclusive but suggest that the Cow Springs uplift may have extended southeast across Black Mesa and that downwarping may not have occurred there in the Late Jurassic. Late Jurassic folds have essentially the same northwest to north-northwest trend as many of the Laramide and possibly younger folds in the region although the older folds tend to be less sinuous. Vertical repetition of lacustrine strata, deposited under conditions especially sensitive to slight tectonic movements, suggest that the movements were episodic. Comparison of the present amount of structural relief with the Late Jurassic structural relief indicates that approximately 3 to 7% of the present-day relief between several of the major basins and uplifts can be attributed to tectonic movements during deposition of the Salt Wash. Thus, it is erroneous to assume that all of the structural deformation in the region occurred during or after the Laramide orogeny. End_of_Article - Last_Page 1351------------

Geochemical Evaluation of Proposed Ore Genesis Models for Colorado Plateau Tabular-Type Uranium-Vanadium Deposits: ABSTRACT

The elemental, isotopic, and mineralogic examination of core samples from the Tony M orebody, a typical Colorado Plateau tabular-type, uranium-vanadium deposit, located in the Henry structural basin of south-central Utah, allows a critical evaluation of proposed ore genesis models. Uranium mineralization is concentrated into two horizontally oriented tabular horizons hosted within the Salt Wash member of the Jurassic Morrison Formation. The ore zones are not strata bound and rise stratigraphically toward the center of the ancestral Henry basin. Preservation of fossil plant debris and the lack of oxidative destruction of iron disulfide minerals in the interval between the uranium-enriched units argue this zone is not the oxidized tongue formed by a roll-type mineralizing p ocess. The selenium-molybdenum trace element pattern is also inconsistent with the roll-front model. The necessary interbedding of gray lacustrine mudstones and nearshore lacustrine sandstones, as required by the lacustrine-humate model, is present within the Tony M deposit. However, absence of quantitatively significant amounts of transported humic substances either associated or remote from mineralization suggests that mudstone-derived organic acids were not involved in uranium localization. Vanadium oxide is the major vanadium-bearing phase within the lower uranium lense whereas vanadium is partitioned within chlorite in the supra-adjacent barren zone. Such a sharp vertical break in vanadium mineralogy implies vanadium deposition within two chemically different environments. The lower ore zone is characterized by isotopically light (^dgr34S ^cong -26^pmil - 46^pmil) FeS2. Bacterial sulfate reduction is shown to be the most likely fractionating agent. The uniformity of the sulfur isotopic composition of the iron disulfide minerals requires a non-depletable sulfate reservoir. Dissolution of gypsum (^dgr34S ^cong + 14^pmil) occurring below the Tony M orebody is demonstrated to be a plausible sulfur source thereby establishing the presence of a sulfate brine. From this data we conclude that the solution-interface model, which postulates uraniferous meteoric fresh water flowing over a denser brine, best explains the genesis of this deposit. End_of_Article - Last_Page 436------------

Depositional Setting of the Salt Wash Member of the Morrison Formation, Southwest Colorado

ABSTRACT The Jurassic Salt Wash Member of the Morrison Formation, southwestern United States, is host to extensive uranium and vanadium mineralization. The ores occur in sandstones deposited in a complex fluvial system. The depositional geometry of the member is that of a wedge-fan. Detailed facies analysis of an area of the mid-paleoslope part of the member (the Slick Rock Uranium District) documents three major sandstone facies interbedded within a sequence of mudstones, siltstones, and thin sandstones. A large-scale trough cross-bedded facies, characterized by broad and generally thin trough crossbeds which rest locally on giant crossbeds as much as 6 m thick and 50 m wide, is the dominant sandstone facies. Paleocurrent azimuths are unimodal and have low consistency ratios indicating little variation in paleocurrent direction. This facies represents deposition in northeast-flowing, low-sinuosity trunk streams. The low-sinuosity streams were confined between leveed banks and probably had low-braiding indexes. Course change was primarily accomplished by avulsion. The second most abundant sandstone facies is primarily characterized by medium- to small-scale trough crossbedded sandstone within lensoid, fining-upward cycles. A progressive vertical decrease in the scale of structures and ariable paleocurrent orientations are characteristic of these depositional units. This facies represents the point bars of meandering streams that, according to paleocurrent and net sand map evidence, acted as tributaries to the low-sinuosity trunk channels. The third sandstone facies, interpreted as crevasse-splay deposits, contains coarsening-upward sandstone packages with variable structures and a distinctive convex geometry. The mudstone, siltstone, and thin sandstone facies averages 50 percent of the member and is subdivided into four subfacies. Oxidized red mudstone with numerous thin, laterally persistent, sandstone and siltstone interbeds represents well-drained floodplain deposits. Less abundant are depositional units composed of calcareous, oxidized silty mudstone with minor sandstone. These units represent sedimentation in shallow ephemeral lakes. Deeper water carbonaceous, gray-green mudstones deposited under anoxic conditions and clay plugs, representing abandoned channel fills, are rare in the district. Detailed analysis of sedimentary facies, sandstone distribution, and regional facies relationships leads to the conclusion that the Salt Wash Member in the Slick Rock District is the product of sedimentation on a fan apron marginal to an alluvial fan or coalesced fan complex. Sandstone thicks that transect the district represent depositional axes of this fluvial system.

Localization of cap-binding protein in subcellular fractions of HeLa cells.

The 26,000-M(r) cap-binding protein was analyzed by a cross-linking assay in cell fractions from uninfected and poliovirus-infected HeLa cells. Cap-binding protein was found in the postribosomal supernatant (S-200) and in the ribosomal salt wash. The cap-binding protein in the S-200 had a sedimentation coefficient of 5 to 7S and lacked the ability to restore translation in extracts of poliovirus-infected cells.

Expression of vaccinia virus early mRNA in Ehrlich ascites tumor cells. 1. Translation of cellular and viral early mRNA in cell-free systems from uninfected and virus-infected cells at the early stage.

Translation of cellular and early vaccinia RNA in nuclease-treated lysates, derived from uninfected and vaccinia-virus-infected cells at the early stage, has been investigated. When using limiting amounts of RNA no discrimination of translation was observed in the infected cells lysates; this conclusion was confirmed by sensitive RNA competition experiments for translation in vitro and also when using two different fractionated systems for protein synthesis in vitro. This absence of detectable discrimination in vitro was established both by comparing incorporation of [35S]methionine into proteins and by analysis of the products thus synthesized by sodium dodecylsulfate gel electrophoresis. However, a modification of the translational machinery from vaccinia-virus-infected cells did occur since the only the ribosomal salt wash derived from infected cells was able to reverse the inhibition of protein synthesis in vitro resulting from excess RNA (control or early). This property of vaccinia-virus-infected cell lysates may result from the synthesis l machinery from vaccinia-virus-infected cells did occur since the only the ribosomal salt wash derived from infected cells was able to reverse the inhibition of protein synthesis in vitro resulting from excess RNA (control or early). This property of vaccinia-virus-infected cell lysates may result from the synthesis l machinery from vaccinia-virus-infected cells did occur since the only the ribosomal salt wash derived from infected cells was able to reverse the inhibition of protein synthesis in vitro resulting from excess RNA (control or early). This property of vaccinia-virus-infected cell lysates may result from the synthesis of an early protein involved in translation or from a better recovery of translational factors from the infected cells, as suggested in the accompanying paper.

Localization of Cap-Binding Protein in Subcellular Fractions of HeLa Cells

The 26,000-M(r) cap-binding protein was analyzed by a cross-linking assay in cell fractions from uninfected and poliovirus-infected HeLa cells. Cap-binding protein was found in the postribosomal supernatant (S-200) and in the ribosomal salt wash. The cap-binding protein in the S-200 had a sedimentation coefficient of 5 to 7S and lacked the ability to restore translation in extracts of poliovirus-infected cells.

Characteristics of the inhibition of protein synthesis by vaccinia virus in non-permissive Chinese hamster ovary cells

Knowing that infection of Chinese hamster ovary (CHO) cells with vaccinia virus results within the first two hours in an overall inhibition of protein synthesis, and that failure of vaccinia to multiply in CHO cells could be related to this effect, we set out to show that inhibition of protein synthesis was characterized by a breakdown of polyribosomes and an accumulation of 80 S monosomes which remained associated at high salt concentrations. Moreover, extracts from infected cells were impaired in their capacity to carry out in vitro protein synthesis. The reduced level of in vitro protein synthesis appeared to be mainly due to an inactive ribosomal fraction and to a certain extent to a decreased activity of the ribosomal salt wash fraction. RNA extracted from infected cells was translated efficiently in reticulocyte lysates. Taken together, the results suggest that in vivo polypeptide synthesis is arrested either as a result of the formation of an inactive 80 S initiation complex or because of a defect in a subsequent elongation event. These general features of inhibition of protein synthesis in CHO cells are discussed in relation to those previously reported for vaccinia permissive cells. L'infection de cellules CHO avec le virus de la vaccine donnant lieu dès la deuxième heure à une inhibition complète de la synthèse protéique, aussi bien virale que cellulaire, et ce phénomène pouvant expliquer le fait que les cellules CHO ne sont pas permissives pour le virus de la vaccine, nous avons voulu mettre en évidence le niveau de l'inhibition de la synthèse protéique dans ce système cellulaire non permissif. Cette inhibition s'accompagne d'une dégradation des polyribosomes et d'une accumulation des monosomes 80 S, les derniers n'étant pas dissociés à forte force ionique. D'autre part, l'activité de synthèse protéique in vitro dans des lysats provenant de cellules infectées est beaucoup plus faible que celle obtenue à partir de lysats de cellules non infectées. L'étude de l'activité des différents constituants des lysats cellulaires après fractionnement et reconstitution a permis de montrer que la fraction ribosomale est la plus touchée par l'infection. Les facteurs de synthèse protéiques associés aux ribosomes et détachés grâce à un traitement par KCl 0,5 M sont également légèrement inactivés par l'infection. Enfin, les ARNm des cellules infectées sont traduits in vitro d'une façon équivalente à ceux des cellules non infectées. L'ensemble des données indique que la synthèse protéique est inhibée in vivo , soit en raison de la formation d'un complexe d'initiation 80 S inactif, soit en raison d'un défaut dans une étape d'élongation. Les résultats de cette étude sont comparés à ceux précédemment obtenus dans l'analyse de systèmes cellulaires permissifs pour le virus de la vaccine.

A bacterial secretory protein requires signal recognition particle for translocation across mammalian endoplasmic reticulum.

In vitro transcription of DNA from plasmid pBR322 was coupled to cell-free translation in a wheat germ system. The major translation product was pre-beta-lactamase. Upon addition of dog pancreas microsomes, the precursor was processed to authentic beta-lactamase as shown by partial NH2-terminal sequence analysis. Processing was linked to translocation into the microsomal vesicles. Salt-extracted microsomes did not process pre-beta lactamase but could be reactivated by purified signal recognition particle, which is the functional component of the salt wash (Walter, P., and Blobel, G. (1980) Proc. Natl. Acad. Sci. U. S. A. 77, 7112-7116). Signal recognition particle alone caused a drastic translation arrest that could be released by salt-depleted membranes. These data are consistent with those obtained for eukaryotic proteins and suggest that co-translational translocation of both bacterial and eukaryotic secretory proteins across the endoplasmic reticulum require identical components.

Bioassay for components regulating eukaryotic gene expression: a chromosomal factor involved in the generation of histone mRNA 3' termini.

We have adapted the oocyte injection procedure for the detection of regulatory components involved in the transcription of a eukaryotic mRNA gene. Injection of the histone gene repeat h22 DNA of Psammechinus miliaris into the Xenopus oocyte nucleus results in correct initiation of the histone mRNAs, but readthrough by RNA polymerase occurs at the 3' end of the H3 histone gene (Hentschel, C. C., Probst, E. & Birnstiel, M. L. (1980) Nature (London) 288, 100-102). Coinjection into the oocyte of a chromosomal salt wash fraction derived from sea urchin embryos results in the generation of authentic 3' termini of the histone H3 mRNA. We have partially purified the protein component by column chromatography and density gradient centrifugation. The regulatory factor binds to heparin columns and, hence, has the properties anticipated of an RNA- or DNA-binding protein. The sedimentation coefficient of the active component was determined to be about 12 S, suggesting a molecular weight of 200,000-250,000.

A translational inhibitor activated in rabbit reticulocyte lysates under high pO 2

An inhibitor of protein synthesis was activated under high oxygen partial pressure (pO 2) in hemin-supplemented and glutathione disulfide-free lysates from rabbit reticulocytes. This inhibitor shared some common features with other translational inhibitors from rabbit reticulocytes; that is, hemin-controlled repressor, glutathione disulfide-activated inhibitor and high pressure-activated inhibitor. It caused biphasic kinetics of inhibition which could be potentiated by ATP. Its activation was prevented by cAMP or glucose 6-phosphate. The high pO 2-inhibitor could be partially purified from post-ribosomal supernatant containing ribosomal salt wash by precipitation between 0–50% (NH 4) 2SO 4-saturation, Sephadex G-100, and DEAE-cellulose chromatography.

The purification of human DNA fragments containing benzpyrene adducts

DNA was isolated from human diploid lung epithelial cells treated in culture with [ 3H]benzpyrene. The DNA contained one covalently bound benzpyrene group per 38 kb and it was digested with a series of restriction endonucleases giving decreasing fragment sizes, and also with DNAase I to 96% acid solubility. The digests were applied to octyl-Sepharose columns under conditions which promote hydrophobic interaction of the benzpyrene groups on the DNA with the octyl groups in the column matrix. Separation of fragments without and with benzpyrene groups was achieved with successive high salt and ethanediol washes. As DNA fragment size is decreased, more DNA-associated benzpyrene is eluted with ethanediol. Under these conditions, DNA from untreated cells is totally removed in the high salt wash and free benzpyrene metabolites are retained on the column. The separation of DNA fragments with covalently-bound hydrophobic benzpyrene groups, from less modified or unmodified DNA will facilitate examination of the distribution of benzpyrene adducts in defined regions of the human genome.

Reconstitution of photosynthetic water splitting in inside-out thylakoid vesicles and identification of a participating polypeptide

Inside-out spinach thylakoid vesicles have been used for inhibition and reconstitution of photosynthetic water splitting. Washing inside-out vesicles with a buffer containing 250 mM NaCl inhibited 75% of the Photosystem II reduction of phenyl- p-benzoquinone. In contrast, the same treatment of right-side-out vesicles gave quite a small inhibition. The site of inhibition was shown by fluorescence induction to be located at the water-splitting side of P-680. The salt-induced inhibition was accompanied by the release of two polypeptides (23 and 16 kDa) from the inner thylakoid surface. Readdition of the salt-washed supernatant or a crude chloroplast extract to the washed inside-out vesicles at low ionic strength gave a 2.7-fold stimulation of the water-splitting activity, thereby restoring about 60% of the activity lost by salt washing. This stimulation was abolished by proteolysis of the reconstituting fractions. Restoration of the water-splitting reaction was accompanied by rebinding of the 23 and 16 kDa polypeptides to the inside-out vesicles. After polypeptide purification by ion-exchange chromatography it was shown that the 23kDa polypeptide was responsible for the restorative effect. These observations provide strong evidence that the 23 kDa polypeptide, electrostatically bound to the inner thylakoid surface, is involved in the photosynthetic water-splitting reaction.

A yeast endoribonuclease stimulated by Novikoff hepatoma small nuclear RNAs U1 and U2

Using [ 3H]m 7Gppp[ 14C]RNA-poly(A) from yeast as a substrate, an endoribonuclease has been detected in enzyme fractions derived from a high salt wash of ribonucleoprotein particles of Saccharomyces cerevisiae . The [ 3H]m 7Gppp[ 14C]RNA-poly(A) seems to be a preferred substrate since other polyribonucleotides are hydrolyzed more slowly, if at all. The enzyme is inhibited by ethidium bromide, but fully double-stranded polyribonucleotides are not hydrolyzed. The hydrolysis of [ 3H]m 7Gppp[ 14C]RNA-poly(A) is stimulated about 2.5-fold by the addition of small nuclear RNAs U1 and U2 of Novikoff hepatoma cells. Results show that the stimulation involves an interaction of the labeled RNA with the small nuclear RNA.

Eukaryotic ribosomal subunit anti-association activity of calf liver is contained in a single polypeptide chain protein of Mr = 25,500 (eukaryotic initiation factor 6).

A protein factor that prevents the reassociation of eukaryotic 40 S and 60 S ribosomal subunits when the Mg+ concentration is raised from 1 to 5 mM has been purified to apparent electrophoretic homogeneity from postribosomal supernatant of calf liver extracts. The purified ribosomal subunit anti-association factor is a relatively heat-sensitive protein consisting of a single polypeptide chain of apparent Mr = 25,500. Direct assay for ribosomal subunit anti-association activity indicates that the majority (greater than 90% of such an activity in calf liver extracts can be accounted for by the presence of this 25,500-dalton protein factor in the postribosomal supernatant. The ribosomal salt wash protein fractions are virtually devoid of any significant ribosomal subunit anti-association or 80 S ribosome dissociation activity. The purified anti-association factor maintains a pool of ribosomal subunits by binding to 60 S ribosomal subunits and preventing them from reassociating with 40 S ribosomal subunits, rather than by dissociating 80 S monosomes. The factor neither binds to, nor seems to interact directly with, 40 S subunits. The properties of this factor are thus similar to wheat germ ribosome dissociation factor (eukaryotic initiation factor 6) described by Russell and Spremulli ((1979) J. Biol. Chem. 254, 8796-8800.

Association of cap-binding protein with eucaryotic initiation factor 3 in initiation factor preparations from uninfected and poliovirus-infected HeLa cells.

Extracts from poliovirus-infected HeLa cells are unable to translate vesicular stomatitis virus or cellular mRNAs in vitro, probably reflecting the poliovirus-induced inhibition of host cell protein synthesis which occurs in vivo. Crude initiation factors from uninfected HeLa cells are able to restore translation of vesicular stomatitis virus mRNA in infected cell lysates. This restoring activity separates into the 0 to 40% ammonium sulfate fractional precipitate of ribosomal salt wash. Restoring activity is completely lacking in the analogous fractions prepared from poliovirus-infected cells. The 0 to 40% ammonium sulfate precipitates from both uninfected and infected cells contain eucaryotic initiation factor 3 (eIF-3), eIf-4B, and the cap-binding protein (CBP), which is detected by means of a cross-linking assay, as well as other proteins. The association of eIF-3 and cap binding protein was examined. The 0 to 40% ammonium sulfate precipitate of ribosomal salt wash from uninfected and infected cells was sedimented in sucrose gradients. Each fraction was examined for the presence of eIF-3 antigens by an antibody blot technique and for the presence of the CBP by cross-linking to cap-labeled mRNAs. From uninfected cells, a major proportion of the CBP cosedimented with eIF-3; however, none of the CBP from infected cells sedimented with eIF-3. The results suggest that the association of the CBP with eIF-3 into a functional complex may have been disrupted during the course of poliovirus infection.

Regulation of protein synthesis in vesicular stomatitis virus-infected mouse L-929 cells by decreased protein synthesis initiation factor 2 activity.

Infection of mouse L-cell spinner cultures by vesicular stomatitis virus (VSV) effected the selective translation of viral mRNA by 4h after viral adsorption. Cell-free systems prepared from mock- and VSV-infected cells reflected this phenomenon; protein synthesis was reduced in the virus-infected cell lysate by approximately 75% compared with the mock-infected (control) lysate. This effect appeared to be specific to protein synthesis initiation since (i) methionine incorporation into protein from an exogenous preparation of initiator methionyl-tRNA gave completely analogous results and (ii) the addition of a ribosomal salt wash (containing protein synthesis initiation factors) stimulated protein synthesis by the infected cell lysate but had no effect on protein synthesis by the control. Micrococcal nuclease-treated (initiation-dependent) VSV-infected cell lysates were not able to translate L-cell mRNA unless they were supplemented with a ribosomal salt wash; a salt wash from ribosomes from uninfected cells effected a quicker recovery than a salt wash from ribosomes from infected cells. When salt wash preparations from ribosomes from uninfected and infected cells were tested for initiation factor 2 (eIF-2)-dependent ternary complex capacity with added GTP and initiator methionyl-tRNA, we found that the two preparations contained equivalent levels of eIF-2. However, initiation complex formation by the factor from virus-infected cells proceeded at a reduced initial rate compared with the control. When the lysates were supplemented with a partially purified eIF-2 preparation, recovery of activity by the infected cell lysate was observed. Mechanisms by which downward regulation of eIF-2 activity might direct the selective translation of viral mRNA in VSV-infected cells are proposed.

Uranium Deposits in Channel Curves of Salt Wash Sandstone Member of Morrison Formation (Late Jurassic), Utah: ABSTRACT

The Salt Wash Member of the Morrison Formation in southeastern Utah is characterized by fluvial sandstone in distinct paleochannels. The deposits are part of a large delta-fan with an apex in the vicinity of the western Grand Canyon. The exhumed channel fills, which excellently expose directional sedimentary structures, were deposited by streams of slight to moderate sinuosity, with occasional sharp bends. Such curves were loci of more conspicuous entrapment and burial of carbonaceous material. Later these areas became highly reducing environments where uranium ores precipitated from ground water percolating through permeable interconnecting channels. Major uranium deposits are more likely to occur in areas where such conditions existed. To determine areas with strong randomness of paleocurrent directions, the vector summation method was applied to the analysis of 2,638 paleocurrent measurements. Because this method is a sensitive measure of dispersion, it was possible to outline areas displaying high and low vector strength values. Areas of high scatter commonly yield low values and polymodal distribution, and areas with low scatter are characterized by high values and unimodal distribution. Thus, areas of high channel sinuosity were successfully outlined. Major known uranium deposits occur most commonly in areas of low vector strength values. Such areas were compared with those containing known ore deposits and those considered favorable for future discoveries, and the results support the conclusion. Although the ve tor method has been used in many paleocurrent studies, this is the first time it has been applied in conjunction with other geologic criteria to delineate and select areas favorable for uranium exploration in sandstone deposits. The results show an important relationship among low paleocurrent vector strength values, carbonaceous material, channel curves, and uranium occurrences in the sandstone channels. End_of_Article - Last_Page 1696------------

Protein synthesis in rabbit reticulocytes XXXI: Purification of Co-eIF-2C and studies of its roles in peptide chain initiation

Co-eIF-2C activity has been purified from high salt wash of reticulocyte ribosomes. The purified preparation is free from detectable levels of eIF-2, Co-eIF-2A, Co-eIF-2B and RF activities. The final step in the purification process involves use of a phosphocellulose chromatography and elution of Co-eIF-2C activity from the column with a buffer containing 2 M urea. This step results in complete removal of the contaminating Co-eIF-2B activity from the purified Co-eIF-2C preparation. Upon polyacrylamide gel electrophoresis, the final Co-eIF-2C preparation shows a single protein band under non-denaturing conditions. In the presence of SDS, the gel picture shows five prominent polypeptide bands (approximate mol. wt: 100,000; 67,000; 53,000; 45,000; and 40,000) and several faint bands. Purified Co-eIF-2C preparation strongly stimulates Met-tRNA f·40S·AUG complex formation in the presence of eIF-2 and such stimulation is almost completely inhibited by HRI plus ATP. This study thus delineates the minimum factor requirements, namely, eIF-2 and Co-eIF-2C for formation of a stable Met-tRNA f·40S·AUG complex.

Localization of Tabular, Sediment-Hosted Uranium-Vanadium Deposits of Henry Structural Basin, Utah: ABSTRACT

Tabular uranium-vanadium mineralization characteristic of the Colorado Plateau occurs in fluvial sandstones of the Salt Wash Member of the Morrison Formation (Jurassic) within the Henry structural basin, south-central Utah. The ore consists of a mineralized interval (MI) of two closely spaced uranium and vanadium-rich zones separated by one barren of uranium but enriched in vanadium. No known stratigraphic feature controls the position of this MI which occurs at successively higher stratigraphic levels toward the interior of the basin. The dominant clay mineral throughout the MI is an unusual vanadium-rich di,trioctahedral chlorite. Laterally continuous with and below the MI, mixed-layer chlorite/smectite and illite/smectite (greater than 75% expandable layers) predominat . Above the MI, kaolinite in sandstone beds and illite/smectite plus kaolinite in bentonitic beds are the dominant authigenic clay minerals. The MI and its unmineralized lateral extensions are bounded, both above and below, by zones rich in authigenic dolomite cement. Petrographic evidence places the dolomite as pre-ore to contemporaneous with ore, and the chlorite contemporaneous with ore. Geochemical and mineralogical data, ^dgr18O to ^dgrD values of clay minerals and ^dgr18O to ^dgr13C values of dolomite indicate the presence of an interface between two isotopically and chemically distinct fluids. The lower fluid was typical of closed-basin evaporated brines with a high Mg/Ca ratio and high SO42- content. The upper fluid was meteo ic water. Elemental zoning patterns and isotopic data suggest that the upper (meteoric) fluid carried the uranium and vanadium to the solution interface, but that ore grade mineralization occurred only where the brine-meteoric water interface intersected horizons with anomalous concentrations of organic matter (dominantly detrital plant debris). End_of_Article - Last_Page 613------------

18] Purification of muscle actin

This chapter explores some of the pitfalls associated with actin purification and to clarify in some detail the correct use and expected result from each step of the widely used muscle actin purification procedure. Typical preparations use about 10 g of acetone powder. The steps include in the purification are following: extraction of acetone powder; filtration using sterile cheesecloth; centrifugation; polymerization; high salt wash: tropomyosin removal; sedimentation of filamentous actin; depolymerization. It is found that extensive dialysis results in eventual dissociation of actin-myosin complexes and appearance of myosin in the final product. Prolonged dialysis can also lead to observable actin proteolysis and should therefore be avoided. Final steps are Clarification of G-actinadn Polymerization. Depending upon individual technique, buffer purity, dialysis times employed, and so forth, the actin preparation can contain small amounts of contaminating protein, including proteolysed actin. Thus, the chapter presents several techniques for further purification of the actin.