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Articles 301 - 330 of 397
Full-Text Articles in Biology
Mechanisms For The Environmental Regulation Of Gene Expression: Ecological Aspects Of Animal Development, Scott F. Gilbert
Mechanisms For The Environmental Regulation Of Gene Expression: Ecological Aspects Of Animal Development, Scott F. Gilbert
Biology Faculty Works
The environment can play a significant role in the production of phenotypes. However, the developmental mechanisms by which the environmental agents effect normal development are Just becoming known. At least three paths have been found through which the environment can modify gene activity. The first is the neuroendocrine route. Here, the nervous system monitors the environment and transfers signals to the endocrine system. The endocrine hormones can then alter gene expression. The second route involves environmental factors that change the methylation pattern of genes, thereby altering their transcriptional capabilities. The third route involves the direct induction of gene expression in …
Gene Expression Maps: The Cartography Of Transcription, Scott F. Gilbert
Gene Expression Maps: The Cartography Of Transcription, Scott F. Gilbert
Biology Faculty Works
No abstract provided.
The Drosophila Lymph Gland As A Developmental Model Of Hematopoiesis, Seung Hye Jung, Cory J. Evans, Christine Uemura, Utpal Banerjee
The Drosophila Lymph Gland As A Developmental Model Of Hematopoiesis, Seung Hye Jung, Cory J. Evans, Christine Uemura, Utpal Banerjee
Biology Faculty Works
Drosophila hematopoiesis occurs in a specialized organ called the lymph gland. In this systematic analysis of lymph gland structure and gene expression, we define the developmental steps in the maturation of blood cells (hemocytes) from their precursors. In particular, distinct zones of hemocyte maturation, signaling and proliferation in the lymph gland during hematopoietic progression are described. Different stages of hemocyte development have been classified according to marker expression and placed within developmental niches: a medullary zone for quiescent prohemocytes, a cortical zone for maturing hemocytes and a zone called the posterior signaling center for specialized signaling hemocytes. This establishes a …
Transgenic Mouse Model Of Tau Pathology In Astrocytes Leading To Nervous System Degeneration, Deepa V. Dabir
Transgenic Mouse Model Of Tau Pathology In Astrocytes Leading To Nervous System Degeneration, Deepa V. Dabir
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Filamentous tau inclusions in neurons and glia are neuropathological hallmarks of sporadic and familial tauopathies. Because tau gene mutations are pathogenic for the autosomal dominant tauopathy "frontotemporal dementia and parkinsonism linked to chromosome 17," tau abnormalities are implicated directly in the onset and/or progression of disease. Although filamentous tau aggregates are acknowledged to play roles in degenerative mechanisms resulting in neuron loss, the contributions of glial tau pathology to neurodegeneration remain essentially unexplored. To begin to elucidate the role of glial pathology in tauopathies, we generated a transgenic (Tg) mouse model of astrocytic tau pathology by expressing the human tau …
Identification And Functional Analysis Of The Essential And Regulatory Light Chains Of The Only Type Ii Myosin Myo1p In Saccharomyces Cerevisiae, J. Luo, Elizabeth Ann Vallen, C. Dravis, S. E. Tcheperegine, B. Drees, E. Bi
Identification And Functional Analysis Of The Essential And Regulatory Light Chains Of The Only Type Ii Myosin Myo1p In Saccharomyces Cerevisiae, J. Luo, Elizabeth Ann Vallen, C. Dravis, S. E. Tcheperegine, B. Drees, E. Bi
Biology Faculty Works
Cytokinesis in Saccharomyces cerevisiae involves coordination between actomyosin ring contraction and septum formation and/or targeted membrane deposition. We show that Mlc1p, a light chain for Myo2p (type V myosin) and lqg1p (IQGAP), is the essential light chain for Myo1p, the only type 11 myosin in S. cerevisiae. However, disruption or reduction of Mlc1p-Myo1p interaction by deleting the Mlc1p binding site on Myo1p or by a point mutation in MLC1, mlc1-93, did not cause any obvious defect in cytokinesis. In contrast, a different point mutation, mlc1-11, displayed defects in cytokinesis and in interactions with Myo2p and lqg1p. These data suggest that …
Calming John Bartram's Passion: Sweden's Scientific Certification Of Philadelphia's Botanist, Robert E. Savage
Calming John Bartram's Passion: Sweden's Scientific Certification Of Philadelphia's Botanist, Robert E. Savage
Biology Faculty Works
No abstract provided.
Foreword, Scott F. Gilbert
Expression Of Mslec1 Transgenes In Alfalfa Plants Causes Symbiotic Abnormalities, Nancy Fujishige
Expression Of Mslec1 Transgenes In Alfalfa Plants Causes Symbiotic Abnormalities, Nancy Fujishige
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Legume lectins have been proposed to have important symbiotic roles during Rhizobium-legume symbioses. To test this hypothesis, the symbiotic responses of transgenic alfalfa plants that express a portion of the putative alfalfa lectin gene MsLEC1 or MsLEC2 in either the antisense or sense orientation were analyzed following inoculation with wild-type Sinorhizobium meliloti 1021. MsLEC1-antisense (LEC1AS) plants were stunted, exhibited hypernodulation, and developed not only abnormally large nodules but also numerous small nodules, both of which senesced prematurely. MsLEC2-antisense plants were intermediate in growth and nodule number compared with LEC1AS and vector control plants. The symbiotic abnormalities of MsLEC1-sense transgene plants …
Djungarian Hamsters Exhibit Temperature-Dependent Dietary Fat Choice In Long Days, Sara Hiebert Burch, Kelley Carl Hauser , '99, Abbas Ebrahim , '00
Djungarian Hamsters Exhibit Temperature-Dependent Dietary Fat Choice In Long Days, Sara Hiebert Burch, Kelley Carl Hauser , '99, Abbas Ebrahim , '00
Biology Faculty Works
Previous studies have shown that whole-animal thermal responses of ectotherms and heterotherms (e.g., hibernators), both of which experience a wide range of body temperatures, are related to the saturation level of somatic lipids, which in turn can be influenced by the ratio of saturated and unsaturated fatty acids in the diet. This study demonstrates that Djungarian hamsters held in long days display ambient temperature dependent choice of dietary fats, increasing their preference for saturated fats when ambient temperature increases ( to 27 degreesC) and later reversing this preference when ambient temperature is returned to its original value ( 8 degreesC). …
Review Of "Embryos In Wax: Models From The Ziegler Studio" By N. Hopwood, Scott F. Gilbert, J. Bard
Review Of "Embryos In Wax: Models From The Ziegler Studio" By N. Hopwood, Scott F. Gilbert, J. Bard
Biology Faculty Works
No abstract provided.
Educating For Social Responsibility: Changing The Syllabus Of Developmental Biology, Scott F. Gilbert, A. Fausto-Sterling
Educating For Social Responsibility: Changing The Syllabus Of Developmental Biology, Scott F. Gilbert, A. Fausto-Sterling
Biology Faculty Works
Developmental biology is deeply embedded in the social issues of our times. Such topics as cloning, stems cells, reproductive technologies, sex selection, environmental hormone mimics and gene therapy all converge on developmental biology. It is therefore critical that developmental biologists learn about the possible social consequences of their work and of the possible molding of their discipline by social forces. We present two models for integrating social issues into the developmental biology curriculum. One model seeks to place discussions of social issues into the laboratory portion of the curriculum; the other model seeks to restructure the course, such that developmental …
The Morphogenesis Of Evolutionary Developmental Biology, Scott F. Gilbert
The Morphogenesis Of Evolutionary Developmental Biology, Scott F. Gilbert
Biology Faculty Works
The early studies of evolutionary developmental biology (Evo-Devo) come from several sources. Tributaries flowing into Evo-Devo came from such disciplines as embryology, developmental genetics, evolutionary biology, ecology, paleontology, systematics, medical embryology and mathematical modeling. This essay will trace one of the major pathways, that from evolutionary embryology to Evo-Devo and it will show the interactions of this pathway with two other sources of Evo-Devo: ecological developmental biology and medical developmental biology. Together, these three fields are forming a more inclusive evolutionary developmental biology that is revitalizing and providing answers to old and important questions involving the formation of biodiversity on …
Web Orientation Of The Banded Garden Spider Argiope Trifasciata (Araneae, Araneidae) In A California Coastal Population, Martina G. Ramirez
Web Orientation Of The Banded Garden Spider Argiope Trifasciata (Araneae, Araneidae) In A California Coastal Population, Martina G. Ramirez
Biology Faculty Works
Magnetic heading (direction the spider’s ventrum faced) and web inclination (degree of slant from the vertical) in Argiope trifasciata Forska°l, a diurnal orb-weaving spider, were studied at a coastal site in southern California for nine weeks in fall 1999. Throughout the study, A. trifasciata largely occupied east-west oriented webs with their venters facing south and southwest. Mean magnetic heading was unaffected by ambient temperature extremes. Inclination levels varied from week to week over an approximately 58 range. However, these changes followed no discernible pattern and were independent both of the sun’s decrease in maximum altitude during the course of the …
Proteasome Inhibition Stabilizes Tau Inclusions In Oligodendroglial Cells That Occur After Treatment With Okadaic Acid, Deepa V. Dabir
Proteasome Inhibition Stabilizes Tau Inclusions In Oligodendroglial Cells That Occur After Treatment With Okadaic Acid, Deepa V. Dabir
Biology Faculty Works
Tau-positive inclusions in oligodendrocytes are consistent neuropathological features of corticobasal degeneration, progressive supranuclear palsy, and frontotemporal dementias with Parkinsonism linked to chromosome 17. Here we show by immunohistochemistry that tau-positive oligodendroglial inclusion bodies also contain the small heat-shock protein (HSP) αB-crystallin but not H HSP70. To study the molecular mechanisms underlying inclusion body formation, we engineered an oligodendroglia cell line (OLN-t40) to overexpress the longest human tau isoform. Treatment of OLN-t40 cells with okadaic acid (OA), an inhibitor of protein phosphatase 2A, caused tau hyperphosphorylation and a decrease in the binding of tau to microtubules. Simultaneously, tau-positive aggregates that also …
The Reactive Genome, Scott F. Gilbert
The Role Of Predator-Induced Polyphenism In The Evolution Of Cognition: A Baldwinian Speculation, Scott F. Gilbert
The Role Of Predator-Induced Polyphenism In The Evolution Of Cognition: A Baldwinian Speculation, Scott F. Gilbert
Biology Faculty Works
No abstract provided.
Regression Approaches For Microarray Data Analysis, Mark R. Segal, Kam D. Dahlquist, Bruce R. Conklin
Regression Approaches For Microarray Data Analysis, Mark R. Segal, Kam D. Dahlquist, Bruce R. Conklin
Biology Faculty Works
A variety of new procedures have been devised to handle the two sample comparison (e.g., tumor versus normal tissue) of gene expression values as measured with microarrays. Such new methods are required in part because of some defining characteristics of microarray-based studies: (i) the very large number of genes contributing expression measures which far exceeds the number of samples (observations) available, and (ii) the fact that by virtue of pathway/network relationships, the gene expression measures tend to be highly correlated. These concerns are exacerbated in the regression setting, where the objective is to relate gene expression, simultaneously for multiple genes, …
Mappfinder: Using Gene Ontology And Genmapp To Create A Global Gene-Expression Profile From Microarray Data, Scott W. Doniger, Nathan Salomonis, Kam D. Dahlquist, Karen Vranizan, Steven C. Lawlor, Bruce R. Conklin
Mappfinder: Using Gene Ontology And Genmapp To Create A Global Gene-Expression Profile From Microarray Data, Scott W. Doniger, Nathan Salomonis, Kam D. Dahlquist, Karen Vranizan, Steven C. Lawlor, Bruce R. Conklin
Biology Faculty Works
MAPPFinder is a tool that creates a global gene-expression profile across all areas of biology by integrating the annotations of the Gene Ontology (GO) Project with the free software package GenMAPP (http://www.GenMAPP.org). The results are displayed in a searchable browser, allowing the user to rapidly identify GO terms with over-represented numbers of geneexpression changes. Clicking on GO terms generates GenMAPP graphical files where gene relationships can be explored, annotated, and files can be freely exchanged.
Thicker Than Blood: Conserved Mechanisms In Drosophila And Vertebrate Hematopoiesis, Cory J. Evans, Volker Hartenstein, Utpal Banerjee
Thicker Than Blood: Conserved Mechanisms In Drosophila And Vertebrate Hematopoiesis, Cory J. Evans, Volker Hartenstein, Utpal Banerjee
Biology Faculty Works
Blood development in Drosophila melanogaster shares several interesting features with hematopoiesis in vertebrates, including spatiotemporal regulation as well as the use of similar transcriptional regulators and signaling pathways. In this review, we describe what is known about hematopoietic development in Drosophila and the various cell types generated and their functions. Additionally, the molecular genetic mechanisms of hematopoietic cell fate determination and commitment within Drosophila blood cell lineages are discussed and compared to vertebrate mechanisms.
Stephen J. Gould, Scott F. Gilbert
From Development To Evolution: The Re-Establishment Of The "Alexander Kowalevsky Medal", A. T. Mikhailov, Scott F. Gilbert
From Development To Evolution: The Re-Establishment Of The "Alexander Kowalevsky Medal", A. T. Mikhailov, Scott F. Gilbert
Biology Faculty Works
The Saint Petersburg Society of Naturalists has reinstated the Alexander O. Kowalevsky Medal. This article announces the winners of the first medals and briefly reviews the achievements of A.O. Kowalevsky,the Russian comparative embryologist whose studies on amphioxus, tunicates and germ layer homologies pioneered evolutionary embryology and confirmed the evolutionary continuity between invertebrates and vertebrates. In re-establishing this international award, the Society is pleased to recognize both the present awardees and the memory of Kowalevsky, whose work pointed to that we now call evolutionary developmental biology.
Genmapp, A New Tool For Viewing And Analyzing Microarray Data On Biological Pathways, Kam D. Dahlquist
Genmapp, A New Tool For Viewing And Analyzing Microarray Data On Biological Pathways, Kam D. Dahlquist
Biology Faculty Works
Describes the computer program Gene Microarray Pathway Profiler (GenMAPP). Tool for viewing and analyzing gene expression data as biological pathways; Evaluation of the gene expression data without prior knowledge of gene function; Representation of biological pathways in a MAPP format.
Analysis Of Protein Localization And Secretory Pathway Function Using The Yeast Saccharomyces Cerevisiae, Elizabeth Ann Vallen
Analysis Of Protein Localization And Secretory Pathway Function Using The Yeast Saccharomyces Cerevisiae, Elizabeth Ann Vallen
Biology Faculty Works
The isolation and characterization of mutants has been crucial in understanding a number of processes in the field of cell biology. In this exercise, students examine the effects of mutations in the secretory pathway on protein localization. Yeast strains deficient for synthesis of histidinol dehydrogenase are transformed with a plasmid encoding a chimeric protein. The chimera contains a signal sequence fused to histidinol dehydrogenase. A strain with a defect in the translocation of secretory proteins into the endoplasmic reticulum (ER) accumulates sufficient histidinol dehydrogenase in the cytoplasm to grow on media lacking histidine. In contrast, yeast proficient for secretion, or …
Investigation Of Four Classes Of Non-Nodulating White Sweetclover (Melilotus Alba Annua Desr.) Mutants And Their Responses To Arbuscular-Mycorrhizal Fungi, Michelle Lum
Biology Faculty Works
The nitrogen-fixing symbiosis between Rhizobiaceae and legumes is one of the best-studied interactions established between prokaryotes and eukaryotes. The plant develops root nodules in which the bacteria are housed, and atmospheric nitrogen is fixed into ammonia by the rhizobia and made available to the plant in exchange for carbon compounds. It has been hypothesized that this symbiosis evolved from the more ancient arbuscular mycorrhizal (AM) symbiosis, in which the fungus associates with roots and aids the plant in the absorption of mineral nutrients, particularly phosphate. Support comes from several fronts: 1) legume mutants where Nod- and Myc- co-segregate, and 2) …
Mutations In Sid2, A Novel Gene In Saccharomyces Cerevisiae, Cause Synthetic Lethality With Sic1 Deletion And May Cause A Defect During S Phase, Matthew D. Jacobson , '97, Claudia C. Muñoz , '99, Kirstin S. Knox , '99, Beth E. Williams , '01, Lenette L. Lu , '02, Frederick Cross , '78, Elizabeth Ann Vallen
Mutations In Sid2, A Novel Gene In Saccharomyces Cerevisiae, Cause Synthetic Lethality With Sic1 Deletion And May Cause A Defect During S Phase, Matthew D. Jacobson , '97, Claudia C. Muñoz , '99, Kirstin S. Knox , '99, Beth E. Williams , '01, Lenette L. Lu , '02, Frederick Cross , '78, Elizabeth Ann Vallen
Biology Faculty Works
SIC1 encodes a nonessential B-type cyclin/CDK inhibitor that functions at the G1/S transition and the exit from mitosis. To understand more completely the regulation of these transitions, Mutations causing synthetic lethality with sic1 Delta were isolated. In this screen, we identified a novel gene, SID2, which encodes an essential protein that appear., to be required for DNA replication or repair. sid2-1 sic1 Delta strains and sid2-21 temperature-sensitive strains arrest preanaphase as large-budded cells with a single nucleus, a short spindle, and an similar to 2C DNA content. RAD9, which is necessary for the DNA damage checkpoint, is required for the …
New Vistas For Developmental Biology, Scott F. Gilbert, R. Tuan
New Vistas For Developmental Biology, Scott F. Gilbert, R. Tuan
Biology Faculty Works
No abstract provided.
Combined, Functional Genomic-Biochemical Approach To Intermediary Metabolism: Interaction Of Acivicin, A Glutamine Amidotransferase Inhibitor, With Escherichia Coli K-12, D. R. Smulski, L. L. Huang, M. P. Mccluskey, M. J. Gladnick Reeve, Amy Cheng Vollmer, T. K. Van Dyk, R. A. Larossa
Combined, Functional Genomic-Biochemical Approach To Intermediary Metabolism: Interaction Of Acivicin, A Glutamine Amidotransferase Inhibitor, With Escherichia Coli K-12, D. R. Smulski, L. L. Huang, M. P. Mccluskey, M. J. Gladnick Reeve, Amy Cheng Vollmer, T. K. Van Dyk, R. A. Larossa
Biology Faculty Works
Acivicin, a modified amino acid natural product, is a glutamine analog. Thus, it might interfere with metabolism by hindering glutamine transport, formation, or usage in processes such as transamidation and translation. This molecule prevented the growth of Escherichia coli in minimal medium unless the medium was supplemented with a purine or histidine, suggesting that the HisHF enzyme, a glutamine amidotransferase, was the target of acivicin action. This enzyme, purified from E. coli, was inhibited by low concentrations of acivicin. Acivicin inhibition was overcome by the presence of three distinct genetic regions when harbored on multicopy plasmids. Comprehensive transcript profiling using …
In Vivo Titration Of Mitomycin C Action By The Presence Of Four Escherichia Coli Genomic Regions On Multicopy Plasmid, Y. Wei, Amy Cheng Vollmer, R. A. Larossa
In Vivo Titration Of Mitomycin C Action By The Presence Of Four Escherichia Coli Genomic Regions On Multicopy Plasmid, Y. Wei, Amy Cheng Vollmer, R. A. Larossa
Biology Faculty Works
Mitomycin C (MMC), a DNA-damaging agent, is a potent inducer of the bacterial SOS response; surprisingly, it has not been used to select resistant mutants from wild-type Escherichia coli. MMC resistance is caused by the presence of any of four distinct E. coli genes (mdfA, gyrl, rob, and sdiA) on high-copy-number vectors. mdfA encodes a membrane efflux pump whose overexpression results in broad-spectrum chemical resistance. The gyrI (also called sbmC) gene product inhibits DNA gyrase activity in vitro, while the rob protein appears to function in transcriptional activation of efflux pumps. SdiA is a transcriptional activator of ftsQAZ genes involved …
Bird Migration Through A Mountain Pass Studied With High Resolution Radar, Ceilometers, And Census, Timothy C. Williams , '64, J. M. Williams, P. G. Williams, P. Stokstad
Bird Migration Through A Mountain Pass Studied With High Resolution Radar, Ceilometers, And Census, Timothy C. Williams , '64, J. M. Williams, P. G. Williams, P. Stokstad
Biology Faculty Works
Autumnal migration was studied with high-resolution radar, ceilometer, and daily census in the area of Franconia Notch, a major pass in the northern Appalachian Mountains. Under synoptic conditions favorable for migration, broadfront movements of migrants toward the south passed over the mountains, often above a temperature inversion. Birds at lower elevations appeared to be influenced by local topography. Birds moving southwest were concentrated along the face of the mountain range. Birds appeared to deviate their flights to follow local topography through the pass. Specific migratory behavior was not associated with species or species groups. Under synoptic conditions unfavorable for southward …
Review Of "Illuminating Life: Selected Papers From Cold Spring Harbor (1903-1969). Volume 1" By J. Witkowski, John B. Jenkins
Review Of "Illuminating Life: Selected Papers From Cold Spring Harbor (1903-1969). Volume 1" By J. Witkowski, John B. Jenkins
Biology Faculty Works
No abstract provided.