Open Access. Powered by Scholars. Published by Universities.®

Life Sciences Commons™

Open Access. Powered by Scholars. Published by Universities.®

Dartmouth College

Series

1993

Articles 1 - 10 of 10

Full-Text Articles in Life Sciences

Efficient Transcriptional Activation Of Many Simple Modular Promoters By Simian Virus 40 Large T Antigen., Philip W. Rice, Charles N. Cole Nov 1993

Efficient Transcriptional Activation Of Many Simple Modular Promoters By Simian Virus 40 Large T Antigen., Philip W. Rice, Charles N. Cole

Dartmouth Scholarship

Simian virus 40 (SV40) large T antigen is a multifunctional protein which plays central roles during both lytic and transforming infections by SV40. It is a potent transcriptional activator and increases expression from the SV40 late promoter and from several cellular promoters. To understand better the transcriptional activation activity of large T antigen, we examined its ability to transactivate a set of simple modular promoters containing one of four upstream activation sequences coupled with one of three different TATA box sequences originally constructed and studied by Taylor and Kingston (Mol. Cell. Biol. 10:165-175, 1990). Large T antigen activated transcription from …

Go to article

The Primary Structure Of A Fungal Chitin Deacetylase Reveals The Function For Two Bacterial Gene Products., Dimitris Kafetzopoulos, George Thireos, John N. Vournakis, Vassilis Bouriotis Sep 1993

The Primary Structure Of A Fungal Chitin Deacetylase Reveals The Function For Two Bacterial Gene Products., Dimitris Kafetzopoulos, George Thireos, John N. Vournakis, Vassilis Bouriotis

Dartmouth Scholarship

Chitin deacetylase (EC 3.5.1.41) hydrolyzes the N-acetamido groups of N-acetyl-D-glucosamine residues in chitin. A cDNA to the Mucor rouxii mRNA encoding chitin deacetylase was isolated, characterized, and sequenced. Protein sequence comparisons revealed significant similarities of the fungal chitin deacetylase to rhizobial nodB proteins and to an uncharacterized protein encoded by a Bacillus stearothermophilus open reading frame. These data suggest the functional homology of these evolutionarily distant proteins. NodB is a chitooligosaccharide deacetylase essential for the biosynthesis of the bacterial nodulation signals, termed Nod factors. The observed similarity of chitin deacetylase to the B. stearothermophilus gene product suggests that this gene …

Go to article

The Interplay Of Light And The Circadian Clock. Independent Dual Regulation Of Clock-Controlled Gene Ccg-2(Eas), Guiseppina Arpaia, Jennifer J. Loros, Jay C. Dunlap, Giorgio Morelli, Guiseppe Macino Aug 1993

The Interplay Of Light And The Circadian Clock. Independent Dual Regulation Of Clock-Controlled Gene Ccg-2(Eas), Guiseppina Arpaia, Jennifer J. Loros, Jay C. Dunlap, Giorgio Morelli, Guiseppe Macino

Dartmouth Scholarship

Ambient light is the major agent mediating entrainment of circadian rhythms and is also a major factor influencing development and morphogenesis. We show that in Neurospora crassa the expression of clock-controlled gene 2 (ccg-2), a gene under the control of the circadian clock and allelic to the developmental gene easy wettable (eas), is regulated by light in wild-type strains. Light elicits a direct and important physiological effect on ccg-2(eas) expression as demonstrated using several mutant Neurospora strains. In white collar mutants (wc-1 and wc-2) that are “blind” to blue light, ccg-2(eas) mRNA shows no variation following illumination with saturating light. …

Go to article

Selection Of Foraging And Nesting Sites By Black-Throated Blue Warblers: Their Relative Influence On Habitat Choice, Benjamin B. Steele Aug 1993

Selection Of Foraging And Nesting Sites By Black-Throated Blue Warblers: Their Relative Influence On Habitat Choice, Benjamin B. Steele

Dartmouth Scholarship

To understand why breeding Black-throated Blue Warblers (Dendroica caerulescens) select forests with dense shrubs, I assessed the value of this habitat in supplying opportunities for foraging and nesting. I predicted that these warblers would select shrub foliage for foraging if foraging substrate was important in their selection of habitat and that they would place their nests in areas of dense shrubs if nest-site availability affected habitat choice. To measure foraging and nest-site selection, I compared the proportion of foraging or nests in a particular habitat element to the availability of that element expressed as a proportion of all …

Go to article

Molecular Cloning Of Infectious Ecotropic Murine Leukemia Virus Ak7 From An Emv-14-Positive Akxl-5 Mouse And The Resistance Of Ak7 To Recognition By Cytotoxic T Lymphocytes., Hillary D. White, William R. Green, Nuria R. Giné Aug 1993

Molecular Cloning Of Infectious Ecotropic Murine Leukemia Virus Ak7 From An Emv-14-Positive Akxl-5 Mouse And The Resistance Of Ak7 To Recognition By Cytotoxic T Lymphocytes., Hillary D. White, William R. Green, Nuria R. Giné

Dartmouth Scholarship

The AKXL-5 recombinant inbred mouse strain is positive for the endogenous ecotropic murine leukemia virus emv-14, the only emv present in its germ line. emv-14 is of particular interest because spleen cells expressing emv-14 virus escape recognition by anti-AKR/Gross virus-specific cytotoxic T lymphocytes. We report here the isolation and characterization of a replication-competent emv clone, pAK7, derived from an AKXL-5 mouse. This clone is novel in that it encodes a variant ecotropic murine leukemia virus that, when expressed in SC.Kb target cells, fails to be recognized efficiently by anti-AKR/Gross virus cytotoxic T lymphocytes. The pAK7 clone can therefore be used …

Go to article

Molecular Basis Of The Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Activase Mutation In Arabidopsis Thaliana Is A Guanine-To-Adenine Transition At The 5'-Splice Junction Of Intron 3, Beverly M. Orozco, C Robertson Mcclung, Jeffrey M. Werneke, William L. Ogren May 1993

Molecular Basis Of The Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Activase Mutation In Arabidopsis Thaliana Is A Guanine-To-Adenine Transition At The 5'-Splice Junction Of Intron 3, Beverly M. Orozco, C Robertson Mcclung, Jeffrey M. Werneke, William L. Ogren

Dartmouth Scholarship

Analysis of the ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activase gene and gene products from Arabidopsis thaliana wild-type plants and the Rubisco activase-deficient mutant strain showed that the rca mutation caused GT to be changed to AT at the 5[prime]-splice junction of intron 3 in the six-intron pre-mRNA. Northern blot analysis, genomic and cDNA sequencing, and primer extension analysis indicated that the mutation causes inefficient and incomplete splicing of the pre-mRNA, resulting in the accumulation of three aberrant mRNAs. One mutant mRNA was identical with wild-type mRNA except that it included intron 3, a second mRNA comprised intron 3 and exons 4 through …

Go to article

Porphyrin Accumulation And Export By Isolated Barley (Hordeum Vulgare) Plastids (Effect Of Diphenyl Ether Herbicides), Judith M. Jacobs, Nicholas J. Jacobs Apr 1993

Porphyrin Accumulation And Export By Isolated Barley (Hordeum Vulgare) Plastids (Effect Of Diphenyl Ether Herbicides), Judith M. Jacobs, Nicholas J. Jacobs

Dartmouth Scholarship

We have investigated the formation of porphyrin intermediates by isolated barley (Hordeum vulgare) plastids incubated for 40 min with the porphyrin precursor 5-aminolevulinate and in the presence and absence of a diphenylether herbicide that blocks protoporphyrinogen oxidase, the enzyme in chlorophyll and heme synthesis that oxidizes protoporphyrinogen IX to protoporphyrin IX. In the absence of herbicide, about 50% of the protoporphyrin IX formed was found in the extraplastidic medium, which was separated from intact plastids by centrifugation at the end of the incubation period. In contrast, uroporphyrinogen, an earlier intermediate, and magnesium protoporphyrin IX, a later intermediate, were located mainly …

Go to article

Two Factors That Bind To Highly Conserved Sequences In Mammalian Type C Retroviral Enhancers., Nancy R. Manley, Mary M. O'Connell, Wanwen Sun, Nancy A. Speck, Nancy Hopkins Apr 1993

Two Factors That Bind To Highly Conserved Sequences In Mammalian Type C Retroviral Enhancers., Nancy R. Manley, Mary M. O'Connell, Wanwen Sun, Nancy A. Speck, Nancy Hopkins

Dartmouth Scholarship

The transcriptional enhancers of the Moloney and Friend murine leukemia viruses (MLV) are important determinants of viral pathogenicity. We used electrophoretic mobility shift and methylation interference assays to study nuclear factors which bind to a region of these enhancers whose sequence is identical between Moloney and Friend viruses and particularly highly conserved among 35 mammalian type C retroviruses whose enhancer sequences have been aligned (E. Golemis, N. A. Speck, and N. Hopkins, J. Virol. 64:534-542, 1990). Previous studies identified sites for the leukemia virus factor b (LVb) and core proteins in this region (N. A. Speck and D. Baltimore, Mol. …

Go to article

Characterization Of A Protein That Binds Multiple Sequences In Mammalian Type C Retrovirus Enhancers., Wanwen Sun, Mary M. O'Connell, Nancy A. Speck Apr 1993

Characterization Of A Protein That Binds Multiple Sequences In Mammalian Type C Retrovirus Enhancers., Wanwen Sun, Mary M. O'Connell, Nancy A. Speck

Dartmouth Scholarship

Mammalian type C retrovirus enhancer factor 1 (MCREF-1) is a nuclear protein that binds several directly repeated sequences (CNGGN6CNGG) in the Moloney and Friend murine leukemia virus (MLV) enhancers (N. R. Manley, M. O'Connell, W. Sun, N. A. Speck, and N. Hopkins, J. Virol. 67:1967-1975, 1993). In this paper, we describe the partial purification of MCREF-1 from calf thymus nuclei and further characterize the binding properties of MCREF-1. MCREF-1 binds four sites in the Moloney MLV enhancer and three sites in the Friend MLV enhancer. Ethylation interference analysis suggests that the MCREF-1 binding site spans two adjacent minor grooves of …

Go to article

Siderophore Utilization By Bradyrhizobium Japonicum, Ora Plessner, Taryn Klapatch, Mary Lou Guerinot Mar 1993

Siderophore Utilization By Bradyrhizobium Japonicum, Ora Plessner, Taryn Klapatch, Mary Lou Guerinot

Dartmouth Scholarship

Bradyrhizobium japonicum USDA 110 and 61A152 can utilize the hydroxamate-type siderophores ferri- chrome and rhodotorulate, in addition to ferric citrate, to overcome iron starvation. These strains can also utilizethepyoverdin-typesiderophorepseudobactinSt3.Theabilitytoutilizeanotherorganism'ssiderophores may confer a selective advantage in the rhizosphere.

Go to article