375 research outputs found
Preface
Because this university, formerly under the well known title of Missouri School of Mines and Metallurgy, has contributed so much to the nation’s and world’s mineral supplies through the work of its well trained graduates, it was considered appropriate that a major symposium be held during its Centennial Year on one of the last major mineral frontiers of the United States......Alaska.
Preliminary planning for the symposium on “Alaska, Its Mineral Potentials and Environmental Challenges” began in the fall of 1969. In January, 1970, Robert E. Carlile and Paul Dean Proctor visited Alaska to meet with some of the petroleum and mineral industry personnel. The purpose of the journey was to personally invite some of the experts who could directly relate to this Centennial Symposium. The warm hospitality, graciousness, and suggestions of industry and government leaders gave much impetus to the finalization of the program and the plans.
Formal invitations were extended to various individuals who had in-depth experience in Alaska or direct interest in the Arctic areas to participate in this Centennial Symposium. Objectives were to give platform presentation and audience discussion to important aspects of the petroleum-solid mineral potential of this frontier state of America and the adjacent arctic lands and continental shelf. Because of the unusual climatic setting other speakers were invited to discuss the challenges of this environment in discovering, recovering, and transporting the potential mineral wealth of Alaska. The state consists mainly of public domain and state lands, hence other speakers were invited to present the government’s views on oil and gas developments on these lands and the Alaskan business communities viewpoint on the possible future progress of Alaska.
Special recognition has been given the various authors of the papers, but exceptional efforts were extended by the moderators who so ably assisted in the symposium presentation. Short biographical and alphabetically listed sketches are included for each of the external moderators with our sincere thanks for their considerable help. Similar concise biographical information on each of the authors is included at the end of each of the papers.
The paper presentations includes an introductory paper on Arctic Ecology, by Dr. John Schindler, Assistant Director of the Naval Research Laboratory, Point Barrow, Alaska. Regrettably, Dr. Max Brewer, Director, Naval Research Laboratory was unable to include his presentation on “What We Should Know About the Arctic Environment”. Following the ecological paper, George Gryc and A1 Weissenborn of the U.S. Geological Survey present data on the energy fuels and solid mineral potentials of Alaska. Dr. Earl Hayes, Chief Scientist of the U.S. Bureau of Mines then relates to the environmental challenges of Alaskan mineral resources. Co-authors, Drs. R. G. McCrossan and R. Procter, of the Canadian Geological Survey, review the mineral potential of Arctic Canada. Dr. A. J. Eardley’s paper on Oil and Gas Reserves in the Siberian Shelf extends the prognostications on the Arctic basin. The latter author specifically asked that it be indicated he was substituting for Russian authors who had been invited but could not attend.
With the good potential for petroleum which exists, consideration was then given to physical exploration by drilling and to the unique problems encountered in the handling of equipment under the rigorous arctic conditions. Robert L. Parker, President of the Parker Drilling Company discusses problems in such an environment. Charles C7 Norris of William Brothers Engineering Company describes the maintenance and operation of facilities and equipment in the Arctic. William Pearn discusses details of “Pipeline Design for Arctic and Subarctic Regions”, and A. V. Cardin, Chief Engineer, TAPS, specifically relates to the environmental challenges facing construction of TAPS. Russell Venn, Vice President, Humble Oil Company, expertly discussed details of the epic voyage of the S. S. Manhattan through the Northwest passage. With the possibility that oil might be transported by ship or submarine from northern Alaska, Robert L. McCollom and William Moore present interesting views on arctic marine terminals and their environmental and engineering considerations.
The practicalities and experience of handling petroleum products under conditions varying from arctic conditions to almost temperate conditions and some of the problems related to pipeline construction and pumping of oil products is dynamically presented by Colonel Frederic Johnson, Chief, Petroleum Supply, U.S. Army. Don Simasko gives his views on the place of the independent operator in this developing region with its attendent problems. Thomas R. Marshall, representing the State of Alaska, succinctly and expertly discusses the regulatory controls on oil and gas in the state.
Mr. W. H. Scott, President of the Alaskan Chamber of Commerce, concisely describes the Alaskan business communities view on the petroleum mineral resource development of his state. The final paper, by C. O. Banks, representing the Anchorage Chamber of Commerce, spells out the optimism of the good people of a great state as it moves into its stride in the 20th century.
These thoughts, views and warnings on “Alaska - Its Mineral Potentials - Its Environmental Challenges” are, therefore, presented in the hope that the reader will gain a deeper appreciation and awareness of Alaska - truly one of the last frontiers of today where, most appropriately, the words of J. Robert Oppenheimer apply:
“Both the man of science and the man of action live always at the edge of mystery, surrounded by it.”
Paul Dean ProctorR. E. Carlil
Tricarballylic ester formation during biosynthesis of fumonisin mycotoxins in \u3ci\u3eFusarium verticillioides\u3c/i\u3e
Fumonisins are agriculturally important mycotoxins produced by the maize pathogen Fusarium verticillioides. The chemical structure of fumonisins contains two tricarballylic esters, which are rare structural moieties and important for toxicity. The mechanism for the tricarballylic ester formation is not well understood. FUM7 gene of F. verticillioides was predicted to encode a dehydrogenase/reductase, and when it was deleted, the mutant produced tetradehydro fumonisins (DH4–FB). MS and NMR analysis of DH4–FB1 indicated that the esters consist of aconitate with a 3′-alkene function, rather than a 2′-alkene function. Interestingly, the purified DH4–FB1 eventually yielded three chromatographic peaks in HPLC. However, MS revealed that the metabolites of the three peaks all had the same mass as the initial single-peak DH4–FB1. The results suggest that DH4–FB1 can undergo spontaneous isomerization, probably including both cis–trans stereoisomerization and 3′- to 2′-ene regioisomerization. In addition, when FUM7 was expressed in Escherichia coli and the resulting enzyme, Fum7p, was incubated with DH4–FB, no fumonisin with typical tricarballylic esters was formed. Instead, new fumonisin analogs that probably contained isocitrate and/or oxalosuccinate esters were formed, which reveals new insight into fumonisin biosynthesis. Together, the data provided both genetic and biochemical evidence for the mechanism of tricarballylic ester formation in fumonisin biosynthesis
Galaxy and mass assembly (GAMA): End of survey report and data release 2
The Galaxy And Mass Assembly (GAMA) survey is one of the largest contemporary spectroscopic surveys of lowredshift galaxies. Covering an area of ~286 deg2 (split among five survey regions) down to a limiting magnitude of r < 19.8 mag, we have collected spectra and reliable redshifts for 238 000 objects using the AAOmega spectrograph on the Anglo-Australian Telescope. In addition, we have assembled imaging data from a number of independent surveys in order to generate photometry spanning the wavelength range 1 nm-1 m. Here, we report on the recently completed spectroscopic survey and present a series of diagnostics to assess its final state and the quality of the redshift data. We also describe a number of survey aspects and procedures, or updates thereof, including changes to the input catalogue, redshifting and re-redshifting, and the derivation of ultraviolet, optical and near-infrared photometry. Finally, we present the second public release ofGAMAdata. In this release, we provide input catalogue and targeting information, spectra, redshifts, ultraviolet, optical and near-infrared photometry, single-component Śersic fits, stellar masses, Hα-derived star formation rates, environment information, and group properties for all galaxies with r < 19.0 mag in two of our survey regions, and for all galaxies with r < 19.4 mag in a third region (72 225 objects in total). The data base serving these data is available at http://www.gama-survey.org/
Requirement of Two Acyltransferases for 4-O-Acylation during Biosynthesis of Harzianum A, an Antifungal Trichothecene Produced by Trichoderma arundinaceum
Trichothecenes are sesquiterpenoid toxins produced by multiple fungi, including plant pathogens, entomopathogens, and saprotrophs. Most of these fungi have the acyltransferase-encoding gene tri18. Even though its function has not been determined, tri18 is predicted to be involved in trichothecene biosynthesis because of its pattern of expression and its location near other trichothecene biosynthetic genes. Here, molecular genetic, precursor feeding, and analytical chemistry experiments indicate that in the saprotroph Trichoderma arundinaceum the tri18-encoded acyltransferase (TRI18) and a previously characterized acyltransferase (TRI3) are required for conversion of the trichothecene biosynthetic intermediate trichodermol to harzianum A, an antifungal trichothecene analog with an octa-2,4,6-trienedioyl acyl group. On the basis of the results, we propose that TRI3 catalyzes trichothecene 4-O-acetylation, and subsequently, TRI18 catalyzes replacement of the resulting acetyl group with octa-2,4,6-trienedioyl to form harzianum A. Thus, the findings provide evidence for a previously unrecognized two-step acylation process during trichothecene biosynthesis in T. arundinaceum and possibly other fungiSIThe Spanish Ministry of Economy and Competitiveness supported this work (MINECO-AGL2015-70671-C2-2-R to S.G.), and the University of León granted L.L. a fellowshi
Analysis of substrate specificity of cytochrome P450 monooxygenases involved in trichothecene toxin biosynthesis
[EN]Trichothecenes are a structurally diverse family of toxic secondary metabolites produced by certain species of multiple fungal genera. All trichothecene analogs share a core 12,13-epoxytrichothec-9-ene (EPT) structure but differ in presence, absence and types of substituents attached to various positions of EPT. Formation of some of the structural diversity begins early in the biosynthetic pathway such that some producing species have few trichothecene biosynthetic intermediates in common. Cytochrome P450 monooxygenases (P450s) play critical roles in formation of trichothecene structural diversity. Within some species, relaxed substrate specificities of P450s allow individual orthologs of the enzymes to modify multiple trichothecene biosynthetic intermediates. It is not clear, however, whether the relaxed specificity extends to biosynthetic intermediates that are not produced by the species in which the orthologs originate. To address this knowledge gap, we used a mutant complementation-heterologous expression analysis to assess whether orthologs of three trichothecene biosynthetic P450s (TRI11, TRI13 and TRI22) from Fusarium sporotrichioides, Trichoderma arundinaceum, and Paramyrothecium roridum can modify trichothecene biosynthetic intermediates that they do not encounter in the organism in which they originated. The results indicate that TRI13 and TRI22 could not modify the intermediates that they do not normally encounter, whereas TRI11 could modify an intermediate that it does not normally encounter. These findings indicate that substrate promiscuity varies among trichothecene biosynthetic P450s. One structural feature that likely impacts the ability of the P450s to use biosynthetic intermediates as substrates is the presence and absence of an oxygen atom attached to carbon atom 3 of EPT.SIOpen Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCL
On the mass‐to‐light ratios of fossil groups. Are they simply dark clusters?
Defined as X‐ray bright galaxy groups with large differences between the luminosities of their brightest and second brightest galaxies, ‘fossil groups’ are believed to be some of the oldest galaxy systems in the Universe. They have therefore been the subject of much recent research. In this work we present a study of 10 fossil group candidates with an average of 33 spectroscopically confirmed members per group, making this the deepest study of its type to date. We also use these data to perform an analysis of the luminosity function of our sample of fossil groups. We confirm the high masses previously reported for many of fossil systems, finding values more similar to those of clusters than of groups. We also confirm the high dynamical mass‐to‐light ratios reported in many previous studies. While our results are consistent with previous studies in many ways, our interpretation is not. This is because we show that, while the luminosities of the bright central galaxies (BCGs) in these systems are consistent with their high dynamical masses, their richnesses (total number of galaxies above some canonical value) are extremely low. This leads us to suggest a new interpretation of fossil systems in which the large differences between the luminosities of their brightest and second brightest galaxies are simply the result of the high BCG luminosities and low richnesses, while the high masses and low richnesses also explain the high mass‐to‐light ratios. Our results therefore suggest that fossil systems can be characterized as cluster‐like in their masses and BCG luminosities, but possessing the richnesses and optical luminosities of relatively poor groups. These findings are not predicted by any of the current models for the formation of fossil groups. Therefore, if this picture is confirmed, current ideas about the formation and evolution of fossil systems will need to be reformulated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/89559/1/j.1365-2966.2011.19625.x.pd
A Deep Space Network Portable Radio Science Receiver
The Radio Science Receiver (RSR) is an open-loop receiver installed in NASA s Deep Space Network (DSN), which digitally filters and records intermediate-frequency (IF) analog signals. The RSR is an important tool for the Cassini Project, which uses it to measure perturbations of the radio-frequency wave as it travels between the spacecraft and the ground stations, allowing highly detailed study of the composition of the rings, atmosphere, and surface of Saturn and its satellites
Identification of polyketide synthase genes required for aspinolide biosynthesis in Trichoderma arundinaceum
https://link.springer.com/article/10.1007/s00253-022-12182-9[EN] The fungus Trichoderma arundinaceum exhibits biological control activity against crop diseases caused by other fungi. Two mechanisms that likely contribute to this activity are upregulation of plant defenses and production of two types of antifungal secondary metabolites: the sesquiterpenoid harzianum A (HA) and the polyketide-derived aspinolides. The goal of the current study was to identify aspinolide biosynthetic genes as part of an effort to understand how these metabolites contribute to the biological control activity of T. arundinaceum. Comparative genomics identified two polyketide synthase genes (asp1 and asp2) that occur in T. arundinaceum and Aspergillus ochraceus, which also produces aspinolides. Gene deletion and biochemical analyses in T. arundinaceum indicated that both genes are required for aspinolide production: asp2 for formation of a 10-member lactone ring and asp1 for formation of a butenoyl subsituent at position 8 of the lactone ring. Gene expression and comparative genomics analyses indicated that asp1 and asp2 are located within a gene cluster that occurs in both T. arundinaceum and A. ochraceus. A survey of genome sequences representing 35 phylogenetically diverse Trichoderma species revealed that intact homologs of the cluster occurred in only two other species, which also produced aspinolides. An asp2 mutant inhibited fungal growth more than the wild type, but an asp1 mutant did not, and the greater inhibition by the asp2 mutant coincided with increased HA production. These findings indicate that asp1 and asp2 are aspinolide biosynthetic genes and that loss of either aspinolide or HA production in T. arundinaceum can be accompanied by increased production of the other metabolite(s).SIPublicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCL
Gemini/GMOS spectra of globular clusters in the Virgo giant elliptical NGC 4649
NGC 4649 (M60) is one of a handful of giant Virgo ellipticals. We have obtained Gemini/GMOS (Gemini North Multi-Object Spectrograph) spectra for 38 globular clusters (GCs) associated with this galaxy. Applying the multi-index χ2 minimization technique of Proctor and Sansom with the single stellar population models of Thomas, Maraston and Korn, we derive ages, metallicities and α-element abundance ratios. We find several young (2-3 Gyr old) supersolar metallicity GCs, while the majority are old (>10 Gyr), spanning a range of metallicities from solar to [Z/H] = -2. At least two of these young GCs are at large projected radii of 17-20 kpc. The galaxy itself shows no obvious signs of a recent starburst, interaction or merger. A trend of decreasing α-element ratio with increasing metallicity is found.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat
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