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Articles 331 - 360 of 397
Full-Text Articles in Biology
Revisiting Women And Feminism In Developmental Biology, Scott F. Gilbert, K. A. Rader
Revisiting Women And Feminism In Developmental Biology, Scott F. Gilbert, K. A. Rader
Biology Faculty Works
No abstract provided.
Continuity And Change: Paradigm Shifts In Neural Induction, Scott F. Gilbert
Continuity And Change: Paradigm Shifts In Neural Induction, Scott F. Gilbert
Biology Faculty Works
No abstract provided.
What Makes The Rhizobia-Legume Symbiosis So Special?, Michelle Lum
What Makes The Rhizobia-Legume Symbiosis So Special?, Michelle Lum
Biology Faculty Works
No abstract provided.
Sugar-Binding Activity Of Pea Lectin Enhances Heterologous Infection Of Transgenic Alfalfa Plants By Rhizobium Leguminosarum Biovar Viciae, Nancy Fujishige
Sugar-Binding Activity Of Pea Lectin Enhances Heterologous Infection Of Transgenic Alfalfa Plants By Rhizobium Leguminosarum Biovar Viciae, Nancy Fujishige
Biology Faculty Works
Transgenic alfalfa (Medicago sativa L. cv Regen) roots carrying genes encoding soybean lectin or pea (Pisum sativum) seed lectin (PSL) were inoculated with Bradyrhizobium japonicum or Rhizobium leguminosarum bv viciae, respectively, and their responses were compared with those of comparably inoculated control plants. We found that nodule-like structures formed on alfalfa roots only when the rhizobial strains produced Nod factor from the alfalfa-nodulating strain, Sinorhizobium meliloti. Uninfected nodule-like structures developed on the soybean lectin-transgenic plant roots at very low inoculum concentrations, but bona fide infection threads were not detected even when B. japonicum produced the appropriate S. meliloti Nod factor. …
Expression Of Mslec1- And Mslec2-Antisense Genes In Alfalfa Plant Lines Causes Severe Embryogenic, Developmental And Reproductive Abnormalities, Laurence M. Brill, Cory J. Evans, Ann M. Hirsch
Expression Of Mslec1- And Mslec2-Antisense Genes In Alfalfa Plant Lines Causes Severe Embryogenic, Developmental And Reproductive Abnormalities, Laurence M. Brill, Cory J. Evans, Ann M. Hirsch
Biology Faculty Works
Although it has been proposed that plant lectins play a number of roles, the function of these proteins in normal plant growth and development has been unclear. To analyze the functions of putative alfalfa lectin genes, lines of transgenic alfalfa plants expressing approximately half of the open reading frame of MsLEC1 or MsLEC2, in the antisense or sense orientation, were established and analyzed. The antisense plants displayed severe abnormalities in embryogenesis, and both vegetative and reproductive development were perturbed. Some differences were observed between MsLEC1- and MsLEC2-antisense plants, and abnormalities were especially severe during the early stages of development in …
Roles Of Hof1p, Bni1p, Bnr1p, And Myo1p In Cytokinesis In Saccharomyces Cerevisiae, Elizabeth Ann Vallen, J. Caviston, E. Bi
Roles Of Hof1p, Bni1p, Bnr1p, And Myo1p In Cytokinesis In Saccharomyces Cerevisiae, Elizabeth Ann Vallen, J. Caviston, E. Bi
Biology Faculty Works
Cytokinesis in Saccharomyces cerevisiae occurs by the concerted action of the actomyosin system and septum formation. Here we report on the roles of HOF1,BNI1, and BNR1 in cytokinesis, focusing on Hof1p. Deletion of HOF1 causes a temperature-sensitive defect in septum formation. A Hof1p ring forms on the mother side of the bud neck in G2/M, followed by the formation of a daughter-side ring. Around telophase, Hof1p is phosphorylated and the double rings merge into a single ring that contracts slightly and may colocalize with the actomyosin structure. Upon septum formation, Hof1p splits into two rings, disappearing upon cell separation. Hof1p …
Mainstreaming Feminist Critique Into The Biology Curriculum, Scott F. Gilbert, Biology And Gender Study Group
Mainstreaming Feminist Critique Into The Biology Curriculum, Scott F. Gilbert, Biology And Gender Study Group
Biology Faculty Works
No abstract provided.
Paradigm Shifts In Neural Induction, Scott F. Gilbert
Paradigm Shifts In Neural Induction, Scott F. Gilbert
Biology Faculty Works
The molecularization of developmental biology was originally seen as a challenge to the integrity of that discipline. However, important new insights from the analysis of gene expression soon transformed the field from one of experimental anatomy to one of developmental genetics. One of the main areas to be transformed from an anatomical to a molecular study was « primary embryonic induction ». The molecular analyses showed that some of the fundamental concepts concluded from the experimental embryological approach to primary embryonic induction were false. First, the neural fate of cells was not being induced. Rather, the epidermal fate was induced …
Genes Classical And Genes Developmental: The Different Uses Of The Gene In Evolutionary Synthesis, Scott F. Gilbert
Genes Classical And Genes Developmental: The Different Uses Of The Gene In Evolutionary Synthesis, Scott F. Gilbert
Biology Faculty Works
Dobzhansky (1964) stated that “Nothing in biology makes sense except in the light of evolution,” and the function of the gene is no exception. The use of genes in population genetics and developmental genetics differs significantly. This is reflected in the roles that genes are postulated to play in evolution. In the Modern Synthesis of population genetics and evolution, genes become manifest by differences in alleles that are active in conferring differential reproductive success in adult individuals. The gene is thought to act as a particulate, atomic unit. In current syntheses of evolution and developmental genetics, important genes are manifest …
Dg93, A Nodule-Abundant Mrna Of Datisca Glomerata With Homology To A Soybean Early Nodulin Gene, Nancy Fujishige
Dg93, A Nodule-Abundant Mrna Of Datisca Glomerata With Homology To A Soybean Early Nodulin Gene, Nancy Fujishige
Biology Faculty Works
We have isolated a 590-bp full-length cDNA clone designated Dg93, an mRNA that is highly expressed in symbiotic root nodules of the actinorhizal host Datisca glomerata. Dg93 mRNA encodes a deduced polypeptide of 105 amino acids with significant identity (74%) to the soybean (Glycine max) early nodulin (ENOD) gene GmENOD93 (Kouchi and Hata, 1993). Dg93 mRNA is abundant in nodules at 4 weeks post inoculation, the earliest time assayed, and steady-state mRNA levels remain elevated 11 weeks after inoculation. Spatial patterns of Dg93 mRNA expression are complex, with transcript accumulation in the nodule lobe meristem, early infection zone, periderm, and …
Responses Of Cam Species To Increasing Atmospheric Co2 Concentrations, Philippa M. Drennan
Responses Of Cam Species To Increasing Atmospheric Co2 Concentrations, Philippa M. Drennan
Biology Faculty Works
Crassulacean acid metabolism (CAM) species show an average increase in biomass productivity of 35% in response to a doubled atmospheric CO2 concentration. Daily net CO2 uptake is similarly enhanced, reflecting in part an increase in chlorenchyma thickness and accompanied by an even greater increase in water-use efficiency. The responses of net CO2 uptake in CAM species to increasing atmospheric CO2 concentrations are similar to those for C3 species and much greater than those for C4 species. Increases in net daily CO2 uptake by CAM plants under elevated atmospheric CO2 concentrations reflect increases in both Rubisco-mediated daytime CO2 uptake and phosphoenolpyruvate …
Mechanisms Of Convergence And Extension By Cell Intercalation, Maxellende Ezin
Mechanisms Of Convergence And Extension By Cell Intercalation, Maxellende Ezin
Biology Faculty Works
The cells of many embryonic tissues actively narrow in one dimension (convergence) and lengthen in the perpendicular dimension (extension). Convergence and extension are ubiquitous and important tissue movements in metazoan morphogenesis. In vertebrates, the dorsal axial and paraxial mesodermal tissues, the notochordal and somitic mesoderm, converge and extend. In amphibians as well as a number of other organisms where these movements appear, they occur by mediolateral cell intercalation, the rearrangement of cells along the mediolateral axis to produce an array that is narrower in this axis and longer in the anteroposterior axis. In amphibians, mesodermal cell intercalation is driven by …
Review Of "Disciplining Reproduction: Modernity, American Life Sciences" By A. E. Clarke, Scott F. Gilbert
Review Of "Disciplining Reproduction: Modernity, American Life Sciences" By A. E. Clarke, Scott F. Gilbert
Biology Faculty Works
No abstract provided.
Gene Flow Among Habitat Patches On A Fragmented Landscape In The Spider Argiope Trifasciata (Araneae: Araneidae), Martina G. Ramirez, Kirsten E. Haakonsen
Gene Flow Among Habitat Patches On A Fragmented Landscape In The Spider Argiope Trifasciata (Araneae: Araneidae), Martina G. Ramirez, Kirsten E. Haakonsen
Biology Faculty Works
The banded garden spider (Argiope trifasciata) is a common orb weaver of old field habitats in the United States. In this study, we determined levels of genetic variability and gene flow among seven populations in central Pennsylvania, based on variation at eight allozyme loci. Mean heterozygosity (observed) per population was 7.5% and mean polymorphism was 39.3%, consistent with levels of variability in other arthropods. Values of GST for the four polymorphic loci (mean GST=0.011) suggest that gene flow prevents the genetic differentiation of these populations. The average number of migrants per generation (Nm) among …
Conceptual Breakthroughs In Developmental Biology, Scott F. Gilbert
Conceptual Breakthroughs In Developmental Biology, Scott F. Gilbert
Biology Faculty Works
No abstract provided.
Wormwholes: A Commentary On K.F. Schaffer's "Genes, Behavior, And Developmental Emergentism", Scott F. Gilbert, E. M. Jorgensen
Wormwholes: A Commentary On K.F. Schaffer's "Genes, Behavior, And Developmental Emergentism", Scott F. Gilbert, E. M. Jorgensen
Biology Faculty Works
Although Caenorhabditis elegans was chosen and modified to be an organism that would facilitate a reductionist program for neurogenetics, recent research has provided evidence for properties that are emergent from the neurons. While neurogenetic advances have been made using C. elegans which may be useful in explaining human neurobiology, there are severe limitations on C. elegans to explain any significant human behavior.
Root Growth Dependence On Soil Temperature For Opuntia Ficus-Indica: Influences Of Air Temperature And A Doubled Co2 Concentration, Philippa M. Drennan
Root Growth Dependence On Soil Temperature For Opuntia Ficus-Indica: Influences Of Air Temperature And A Doubled Co2 Concentration, Philippa M. Drennan
Biology Faculty Works
1. Root elongation as a function of soil temperature was determined for the CAM succulent Opuntia ficus-indica, under three different day/night air temperatures (15 °C/5 °C, 25 °C/15 °C and 35 °C/25 °C) and an ambient (360 μmol mol-1) vs a doubled CO2 concentration (720 μmol mol-1) at 25 °C/15 °C, the optimum temperature for net CO2 uptake. 2. Root elongation occurred at soil temperatures from 12 °C (at 15 °C/5 °C) to 43 °C (at 35 °C/25 °C) with optimum temperatures of 27-30 °C, similar to other CAM succulents and consistent with the distribution of this shallow-rooted species in …
Life Of Alexander G. Gurwitsch And His Relevant Contribution To The Theory Of Morphogenetic Fields, L. V. Beloussov, J. M. Opitz, Scott F. Gilbert
Life Of Alexander G. Gurwitsch And His Relevant Contribution To The Theory Of Morphogenetic Fields, L. V. Beloussov, J. M. Opitz, Scott F. Gilbert
Biology Faculty Works
No abstract provided.
Loss Of Matrix Adhesion Triggers Rapid Transformation-Selective Apoptosis In Fibroblasts, G. Mcgill, A. Shimamura, R. C. Bates, Robert E. Savage, D. E. Fisher
Loss Of Matrix Adhesion Triggers Rapid Transformation-Selective Apoptosis In Fibroblasts, G. Mcgill, A. Shimamura, R. C. Bates, Robert E. Savage, D. E. Fisher
Biology Faculty Works
Cell–matrix and cell–cell adhesion are recognized physiological determinants of cell growth and survival. In epithelial and endothelial cell systems, oncogenic transformation has in several cases been shown to confer resistance to apoptosis upon depriving cells of substrate adhesion. We examined the effects of oncogenic transformation in adherent versus adhesion- deprived primary embryonic fibroblasts. Whereas untransformed early passage fibroblasts undergo cell cycle arrest, their Myc/Ras- or E1A/Ras-transformed counterparts rapidly enter apoptosis when placed into suspension. This phenomenon also occurs upon incubation with a soluble, RGD-containing integrin ligand and is blocked by a peptide antagonist to ICE family proteases or by aggregation …
Detection Of Dna Damage By Use Of Escherichia Coli Carrying Reca'::Lux, Uvra'::Lux, And Alka'::Lux Reporter Plasmids, Amy Cheng Vollmer, S. Belkin, D. R. Smulski, T. K. Van Dyk, R. A. Larossa
Detection Of Dna Damage By Use Of Escherichia Coli Carrying Reca'::Lux, Uvra'::Lux, And Alka'::Lux Reporter Plasmids, Amy Cheng Vollmer, S. Belkin, D. R. Smulski, T. K. Van Dyk, R. A. Larossa
Biology Faculty Works
Plasmids were constructed in which DNA damage-inducible promoters recA, uvrA, and alkA from Escherichia coli were fused to the Vibrio fischeri luxCDABE operon. Introduction of these plasmids into E. coli allowed the detection of a dose-dependent response to DNA-damaging agents, such as mitomycin and UV irradiation. Bioluminescence was measured in real time over extended periods. The fusion of the recA promoter to luxCDABE showed the most dramatic and sensitive responses. lexA dependence of the bioluminescent SOS response was demonstrated, confirming that this biosensor's reports were transmitted by the expected regulatory circuitry. Comparisons were made between luxCDABE and lacZ fusions to …
How Cells Learn, How Cells Teach: Induction And Education In The Body, Scott F. Gilbert, S. Borish
How Cells Learn, How Cells Teach: Induction And Education In The Body, Scott F. Gilbert, S. Borish
Biology Faculty Works
No abstract provided.
Waelsch, Salome Gluecksohn (B. 1907), Scott F. Gilbert
Waelsch, Salome Gluecksohn (B. 1907), Scott F. Gilbert
Biology Faculty Works
No abstract provided.
Expression Of Early Nodulin Genes In Alfalfa Mycorrhizae Indicates That Signal Transduction Pathways Used In Forming Arbuscular Mycorrhizae And Rhizobium-Induced Nodules May Be Conserved, Nancy Fujishige, Michelle R. Lum
Expression Of Early Nodulin Genes In Alfalfa Mycorrhizae Indicates That Signal Transduction Pathways Used In Forming Arbuscular Mycorrhizae And Rhizobium-Induced Nodules May Be Conserved, Nancy Fujishige, Michelle R. Lum
Biology Faculty Works
Transcripts for two genes expressed early in alfalfa nodule development (MsENOD40 and MsENOD2) are found in mycorrhizal roots, but not in noncolonized roots or in roots infected with the fungal pathogen Rhizoctonia solani. These same two early nodulin genes are expressed in uninoculated roots upon application of the cytokinin 6-benzylaminopurine. Correlated with the expression of the two early nodulin genes, we found that mycorrhizal roots contain higher levels of trans-zeatin riboside than nonmycorrhizal roots. These data suggest that there may be conservation of signal transduction pathways between the two symbioses-nitrogen-fixing nodules and phosphate-acquiring mycorrhizae.
Oxidative Stress Detection With Escherichia Coli Harboring A Katg'::Lux Fusion, S. Belkin, D. R. Smulski, Amy Cheng Vollmer, T. K. Van Dyk, R. A. Larossa
Oxidative Stress Detection With Escherichia Coli Harboring A Katg'::Lux Fusion, S. Belkin, D. R. Smulski, Amy Cheng Vollmer, T. K. Van Dyk, R. A. Larossa
Biology Faculty Works
A plasmid containing a transcriptional fusion of the Escherichia coli katG promoter to a truncated Vibrio fischeri lux operon (luxCDABE) was constructed. An E. coli strain bearing this plasmid (strain DPD2511) exhibited low basal levels of luminescence, which increased up to 1,000-fold in the presence of hydrogen peroxide, organic peroxides, redox-cycling agents (methyl viologen and menadione), a hydrogen peroxide-producing enzyme system (xanthine and xanthine oxidase), and cigarette smoke. An oxyR deletion abolished hydrogen peroxide-dependent induction, confirming that oxyR controlled katG'::lux luminescence. Light emission was also induced by ethanol by an unexplained mechanism. A marked synergistic response was observed when cells …
Neotropical Bird Migration During The Ice Ages: Orientation And Ecology, Timothy C. Williams , '64, T. Webb Iii
Neotropical Bird Migration During The Ice Ages: Orientation And Ecology, Timothy C. Williams , '64, T. Webb Iii
Biology Faculty Works
Reconstruction of breeding habitat of North American Neotropical migrants 18,000 years ago and 9,000 years ago indicated major shifts in both location and composition of plant communities relative to present conditions. Increased vegetation in xeric areas may have compensated, at least in part, for the reduction in breeding habitat due to glaciation. Autumnal flights of Neotropical passerine migrants flying on constant headings from North America to Central and South America were simulated under present wind conditions and for winds during periods of glaciation at 18,000 and 9,000 years ago. The 155 degrees average headings currently observed for Atlantic migrants were …
Genetic Variability And Gene Flow In Metepeira Ventura (Araneae, Araneidae), Martina G. Ramirez
Genetic Variability And Gene Flow In Metepeira Ventura (Araneae, Araneidae), Martina G. Ramirez
Biology Faculty Works
Levels of genetic variability and gene flow among three populations of Metepeira ventura o n Santa Catalina Island, California, were evaluated based on variation at 10 gene loci . Mean heterozygosity (observed) per population was 10 .4% and mean polymorphism was 36 .7%, consistent with levels of variabilit y in other arthropods. Values of FST for the five polymorphic loci (mean FST = 0 .009) suggest that gene flow prevents the genetic differentiation of these populations . The average number of migrants per generation (Nm) among these populations is estimated to be 28 .6 . The lack of inter-population genetic …
Responses To Toxicants Of An Escherichia Coli Strain Carrying A Uspa'::Lux Genetic Fusion And An E. Coli Strain Carrying A Grpe'::Lux Fusion Are Similar, T. K. Van Dyk, D. R. Smulski, T. R. Reed, S. Belkin, Amy Cheng Vollmer, R. A. Larossa
Responses To Toxicants Of An Escherichia Coli Strain Carrying A Uspa'::Lux Genetic Fusion And An E. Coli Strain Carrying A Grpe'::Lux Fusion Are Similar, T. K. Van Dyk, D. R. Smulski, T. R. Reed, S. Belkin, Amy Cheng Vollmer, R. A. Larossa
Biology Faculty Works
A transcriptional fusion of the Escherichia coli uspA promoter to luxCDABE was characterized and compared with a heat shock-responsive grpE'::lux fusion. Similarities in range and rank order of inducing conditions were observed; however, the magnitude of induction was typically greater for the grpE'::lux fusion strain.
Synergistic Induction Of The Heat Shock Response In Escherichia Coli By Simultaneous Treatment With Chemical Inducers, T. K. Van Dyk, T. R. Reed, Amy Cheng Vollmer, R. A. Larossa
Synergistic Induction Of The Heat Shock Response In Escherichia Coli By Simultaneous Treatment With Chemical Inducers, T. K. Van Dyk, T. R. Reed, Amy Cheng Vollmer, R. A. Larossa
Biology Faculty Works
No abstract provided.
Mutations In Rad27 Define A Potential Link Between G₁ Cyclins And Dna Replication, Elizabeth Ann Vallen, Frederick R. Cross , '78
Mutations In Rad27 Define A Potential Link Between G₁ Cyclins And Dna Replication, Elizabeth Ann Vallen, Frederick R. Cross , '78
Biology Faculty Works
The yeast Saccharomyces cerevisiae has three G1 cyclin (CLN) genes with overlapping functions. To analyze the functions of the various CLN genes, we examined mutations that result in lethality in conjunction with loss of cln1 and cln2. We have isolated alleles of RAD27/ERC11/YKL510, the yeast homolog of the gene encoding flap endonuclease 1, FEN-1.cln1 cln2 rad27/erc11 cells arrest in S phase; this cell cycle arrest is suppressed by the expression of CLN1 or CLN2 but not by that of CLN3 or the hyperactive CLN3-2. rad27/erc11 mutants are also defective in DNA damage repair, as determined by their increased sensitivity to …
Review Of "Correspondence: Karl Ernst Von Baer [1792-1876] And Anton Dohrn [1840-1909]" By C. Groeben And J. Oppenheimer, Scott F. Gilbert
Review Of "Correspondence: Karl Ernst Von Baer [1792-1876] And Anton Dohrn [1840-1909]" By C. Groeben And J. Oppenheimer, Scott F. Gilbert
Biology Faculty Works
No abstract provided.