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

Biology Commons™

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

Genetics

Discipline
Institution
Publication Year
Publication
Publication Type
File Type

Articles 211 - 233 of 233

Full-Text Articles in Biology

An Essential Role For Endocytosis Of Rhodopsin Through Interaction Of Visual Arrestin With The Ap-2 Adaptor, Nicholas R. Orem, Luxi Xia, Patrick J. Dolph May 2006

An Essential Role For Endocytosis Of Rhodopsin Through Interaction Of Visual Arrestin With The Ap-2 Adaptor, Nicholas R. Orem, Luxi Xia, Patrick J. Dolph

Dartmouth Scholarship

Previously, we have identified a class of retinal degeneration mutants in Drosophila in which the normally transient interaction between arrestin2 (Arr2) and rhodopsin is stabilized and the complexes are rapidly internalized into the cell body by receptor-mediated endocytosis. The accumulation of protein complexes in the cytoplasm eventually results in photoreceptor cell death. We now show that the endocytic adapter protein AP-2 is essential for rhodopsin endocytosis through an Arr2-AP-2beta interaction, and mutations in Arr2 that disrupt its interaction with the beta subunit of AP-2 prevent endocytosis-induced retinal degeneration. We further demonstrate that if the interaction between Arr2 and AP-2 is …

Go to article

The Relationship Between Frq-Protein Stability And Temperature Compensation In The Neurospora Circadian Clock, Peter Ruoff, Jennifer J. Loros, Jay C. Dunlap Dec 2005

The Relationship Between Frq-Protein Stability And Temperature Compensation In The Neurospora Circadian Clock, Peter Ruoff, Jennifer J. Loros, Jay C. Dunlap

Dartmouth Scholarship

Temperature compensation is an important property of all biological clocks. In Neurospora crassa, negative-feedback regulation on the frequency (frq) gene's transcription by the FRQ protein plays a central role in the organism's circadian pacemaker. Earlier model calculations predicted that the stability of FRQ should determine the period length of Neurospora's circadian rhythm as well as the rhythm's temperature compensation. Here, we report experimental FRQ protein stabilities in frq mutants at 20 degrees C and 25 degrees C, and estimates of overall activation energies for mutant FRQ protein degradation. The results are consistent with earlier model predictions, i.e., temperature compensation of …

Go to article

The Effect Of Rooibos Tea (Aspalathus Linearis) On The Survival And Transformation Of C3h-Bt1 Mouse Fibroblasts, Krista M. Beach, Paul J. Smith Apr 2005

The Effect Of Rooibos Tea (Aspalathus Linearis) On The Survival And Transformation Of C3h-Bt1 Mouse Fibroblasts, Krista M. Beach, Paul J. Smith

Honors Capstones

Capstone submitted as a graduation requirement for the BSU Honors Program.

Go to article

From The Cover: Assignment Of An Essential Role For The Neurospora Frequency Gene In Circadian Entrainment To Temperature Cycles, Antonio M. Pregueiro, Nathan Price-Lloyd, Deborah Bell-Pedersen, Christian Heintzen, Jennifer J. Loros, Jay C. Dunlap Feb 2005

From The Cover: Assignment Of An Essential Role For The Neurospora Frequency Gene In Circadian Entrainment To Temperature Cycles, Antonio M. Pregueiro, Nathan Price-Lloyd, Deborah Bell-Pedersen, Christian Heintzen, Jennifer J. Loros, Jay C. Dunlap

Dartmouth Scholarship

Circadian systems include slave oscillators and central pacemakers, and the cores of eukaryotic circadian clocks described to date are composed of transcription and translation feedback loops (TTFLs). In the model system Neurospora, normal circadian rhythmicity requires a TTFL in which a White Collar complex (WCC) activates expression of the frequency (frq) gene, and the FRQ protein feeds back to attenuate that activation. To further test the centrality of this TTFL to the circadian mechanism in Neurospora, we used low-amplitude temperature cycles to compare WT and frq-null strains under conditions in which a banding rhythm was elicited. WT cultures were entrained …

Go to article

Pf15p Is The Chlamydomonas Homologue Of The Katanin P80 Subunit And Is Required For Assembly Of Flagellar Central Microtubules, Erin E. Dymek, Paul A. Lefebvre, Elizabeth F. Smith Aug 2004

Pf15p Is The Chlamydomonas Homologue Of The Katanin P80 Subunit And Is Required For Assembly Of Flagellar Central Microtubules, Erin E. Dymek, Paul A. Lefebvre, Elizabeth F. Smith

Dartmouth Scholarship

Numerous studies have indicated that the central apparatus plays a significant role in regulating flagellar motility, yet little is known about how the central pair of microtubules or their associated projections assemble. Several Chlamydomonas mutants are defective in central apparatus assembly. For example, mutant pf15 cells have paralyzed flagella that completely lack the central pair of microtubules. We have cloned the wild-type PF15 gene and confirmed its identity by rescuing the motility and ultrastructural defects in two pf15 alleles, the original pf15a mutant and a mutant generated by insertional mutagenesis. Database searches using the 798-amino-acid polypeptide predicted from the complete …

Go to article

Pcr And 16s Rdna Sequencing For Identifying And Comparing Gram-Negative Bacteria, Molly Truax May 2004

Pcr And 16s Rdna Sequencing For Identifying And Comparing Gram-Negative Bacteria, Molly Truax

Honors Capstones

Capstone submitted as a graduation requirement for the BSU Honors Program.

Go to article

Estimating Metazoan Divergence Times With A Molecular Clock, Kevin J. Peterson, Jessica B. Lyons, Kristin S. Nowak, Carter M. Takacs, Matthew J. Wargo, Mark A. Mcpeek Apr 2004

Estimating Metazoan Divergence Times With A Molecular Clock, Kevin J. Peterson, Jessica B. Lyons, Kristin S. Nowak, Carter M. Takacs, Matthew J. Wargo, Mark A. Mcpeek

Dartmouth Scholarship

Accurately dating when the first bilaterally symmetrical animals arose is crucial to our understanding of early animal evolution. The earliest unequivocally bilaterian fossils are 555 million years old. In contrast, molecular-clock analyses calibrated by using the fossil record of vertebrates estimate that vertebrates split from dipterans (Drosophila) 900 million years ago (Ma). Nonetheless, comparative genomic analyses suggest that a significant rate difference exists between vertebrates and dipterans, because the percentage difference between the genomes of mosquito and fly is greater than between fish and mouse, even though the vertebrate divergence is almost twice that of the dipteran. Here we show …

Go to article

A Dominant-Negative Fur Mutation In Bradyrhizobium Japonicum, Heather P. Benson, Kristin Levier, Mary Lou Guerinot Mar 2004

A Dominant-Negative Fur Mutation In Bradyrhizobium Japonicum, Heather P. Benson, Kristin Levier, Mary Lou Guerinot

Dartmouth Scholarship

In many bacteria, the ferric uptake regulator (Fur) protein plays a central role in the regulation of iron uptake genes. Because iron figures prominently in the agriculturally important symbiosis between soybean and its nitrogen-fixing endosymbiont Bradyrhizobium japonicum, we wanted to assess the role of Fur in the interaction. We identified a fur mutant by selecting for manganese resistance. Manganese interacts with the Fur protein and represses iron uptake genes. In the presence of high levels of manganese, bacteria with a wild-type copy of the furgene repress iron uptake systems and starve for iron, whereas fur mutants fail to …

Go to article

Evidence For An Epigenetic Mechanism By Which Hsp90 Acts As A Capacitor For Morphological Evolution, Vincent E. Sollars, Xiangyi Lu, Li Xiao, Xiaoyan Wang, Mark D. Garfinkel, Douglas M. Ruden Dec 2002

Evidence For An Epigenetic Mechanism By Which Hsp90 Acts As A Capacitor For Morphological Evolution, Vincent E. Sollars, Xiangyi Lu, Li Xiao, Xiaoyan Wang, Mark D. Garfinkel, Douglas M. Ruden

Biochemistry and Microbiology

Morphological alterations have been shown to occur in Drosophila melanogaster when function of Hsp90 (heat shock 0-kDa protein 1α, encoded by Hsp83) is compromised during development1. Genetic selection maintains the altered phenotypes in subsequent generations1. Recent experiments have shown, however, that phenotypic variation still occurs in nearly isogenic recombinant inbred strains of Arabidopsis thaliana2. Using a sensitized isogenic D. melanogaster strain, iso-KrIf-1, we confirm this finding and present evidence supporting an epigenetic mechanism for Hsp90’s capacitor function, whereby reduced activity of Hsp90 induces a heritably altered chromatin state. The altered chromatin state is evidenced by ectopic expression …

Go to article

Mad2 And Bubr1 Function In A Single Checkpoint Pathway That Responds To A Loss Of Tension, Katie Shannon, Julie C. Canman, Edward D. Salmon Oct 2002

Mad2 And Bubr1 Function In A Single Checkpoint Pathway That Responds To A Loss Of Tension, Katie Shannon, Julie C. Canman, Edward D. Salmon

Biological Sciences Faculty Research & Creative Works

The spindle checkpoint monitors microtubule attachment and tension at kinetochores to ensure proper chromosome segregation. Previously, PtK1 cells in hypothermic conditions (23°C) were shown to have a pronounced mitotic delay, despite having normal numbers of kinetochore microtubules. At 23°C, we found that PtK1 cells remained in metaphase for an average of 101 min, compared with 21 min for cells at 37°C. The metaphase delay at 23°C was abrogated by injection of Mad2 inhibitors, showing that Mad2 and the spindle checkpoint were responsible for the prolonged metaphase. Live cell imaging showed that kinetochore Mad2 became undetectable soon after chromosome congression. Measurements …

Go to article

Neurospora Clock-Controlled Gene 9 (Ccg-9) Encodes Trehalose Synthase: Circadian Regulation Of Stress Responses And Development, Mari L. Shinohara, Alejandro Correa, Deborah Bell-Pedersen, Jay C. Dunlap, Jennifer J. Loros Feb 2002

Neurospora Clock-Controlled Gene 9 (Ccg-9) Encodes Trehalose Synthase: Circadian Regulation Of Stress Responses And Development, Mari L. Shinohara, Alejandro Correa, Deborah Bell-Pedersen, Jay C. Dunlap, Jennifer J. Loros

Dartmouth Scholarship

The circadian clock of Neurospora crassa regulates the rhythmic expression of a number of genes encoding diverse functions which, as an ensemble, are adaptive to life in a rhythmic environment of alternating levels of light and dark, warmth and coolness, and dryness and humidity. Previous differential screens have identified a number of such genes based solely on their cycling expression, including clock-controlled gene 9 (ccg-9). Sequence analysis now shows the predicted CCG-9 polypeptide to be homologous to a novel form of trehalose synthase; as such it would catalyze the synthesis of the disaccharide trehalose, which plays an important …

Go to article

Characterization Of A Non-Ribosomal Peptide From Agrobacterium Tumefaciens, Graham Strub May 2001

Characterization Of A Non-Ribosomal Peptide From Agrobacterium Tumefaciens, Graham Strub

Honors Theses

The current efforts underway to sequence the genome of Agrobacterium tumefaciens have led to the discovery of a large region of DNA (52kb) with a strong homology to several polyketide synthetase genes. This was a matter of great interest to the Agrobacterium project; no current literature documents the production of a polyketide or non:iibosomal peptide from Agrobacterium. Furthermore, the multi-domain enzymes coded by these polyketide synthetase genes in other bacterial species are responsible for synthesizing several toxins, many which act as antibiotic agents {8, 9, 12, 16). This was also of great interest, since Agrobacterium is not known to produce …

Go to article

Scientific Investigation Of The Plant Pathogen Agrobacterium Tumefaciens, Casey M. Flanagan, Christopher B. Crowell Ii, Bryan P. Markelz Jan 2000

Scientific Investigation Of The Plant Pathogen Agrobacterium Tumefaciens, Casey M. Flanagan, Christopher B. Crowell Ii, Bryan P. Markelz

Honors Theses

A. tumefaciensis a plant pathogen and causative agent of Crown Gall Disease, an ailment that results in the development of tumors in plants. It is a unique organism in that it is the only known non-viral pathogen that transfers its DNA into the host cell. Consequently, the majority of the research conducted on A. tumefaciensinvestigates its mechanism of infection. However, A. tumefaciensis also rare to the bacterial world in that its genome is comprised of two chromosomes: one circular and one linear. Most other bacteria only have one circular chromosome. This area of research has been grossly overlooked and therefore …

Go to article

Testosterone Effects On Renal Norepinephrine Content And Release In Rats With Different Y Chromosomes, Thomas J. Jones, Gail Dunphy, Amy Milsted, Daniel Ely Nov 1998

Testosterone Effects On Renal Norepinephrine Content And Release In Rats With Different Y Chromosomes, Thomas J. Jones, Gail Dunphy, Amy Milsted, Daniel Ely

Biology Faculty Research

The Y chromosome in spontaneously hypertensive rats (SHR) and stroke-prone rats has been shown to contain a locus that contributes to the hypertensive effect; both the sympathetic nervous system and testosterone may be involved. The objective of this study was to look at the effects of testosterone on renal norepinephrine (NE) release and content in the isolated perfused kidney in different Y chromosome backgrounds. The study involved male SHR, Wistar-Kyoto rats (WKY), and 2 consomic strains with different Y chromosomes (n=5 to 8 per group). Adult animals were castrated, and implants containing testosterone propionate were placed at the base of …

Go to article

Heritability Of Expression Of The 70kd Heat-Shock Protein In Drosophila Melanogaster And Its Relevance To The Evolution Of Thermotolerance, Robert A. Krebs, Martin E. Feder, Jeehyun Lee Jun 1998

Heritability Of Expression Of The 70kd Heat-Shock Protein In Drosophila Melanogaster And Its Relevance To The Evolution Of Thermotolerance, Robert A. Krebs, Martin E. Feder, Jeehyun Lee

Biological, Geological, and Environmental Faculty Publications

The principle inducible heat-shock protein of Drosophila melanogasrer, Hsp70, contributes to thermotolerance throughout the entire life cycle of the species but may also reduce fitness in some life stages. In principle, selection might maximize the benefits of Hsp70 expression relative to its costs by adjusting the magnitude of Hsp70 expression for each life-cycle stage independently. Therefore we examined whether the magnitude of Hsp70 ex pre sion varied during the life cycle and the relationship of this variation to several life-history traits. For 28 isofemale lines derived from a single natural population, estimates of heritable variation in Hsp70 expression ranged between …

Go to article

Evolutionary Genetics Of Canyon Treefrogs (Hyla Arenicolor), Roy A. Murray May 1997

Evolutionary Genetics Of Canyon Treefrogs (Hyla Arenicolor), Roy A. Murray

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Population genetics is the study of the mechanisms that cause genetic change in populations over time. Genetic changes may lead to both adaptive evolution and speciation. While the former process is fairly well understood, many questions remain unanswered with regard to the process of speciation. How important is population isolation in the process of speciation? How long must populations be isolated before speciation is complete? Are the genetic changes that take place during speciation caused mainly by natural selection or does genetic drift play a substantial role? Can genetic drift alone lead to reproductive isolation? These types of questions have …

Go to article

Homology Among The Autosomal Chromosomes Of Boophilus Annulatus (Say) And B. Microplus (Canestrini), Bonnie S. Gunn May 1997

Homology Among The Autosomal Chromosomes Of Boophilus Annulatus (Say) And B. Microplus (Canestrini), Bonnie S. Gunn

Theses and Dissertations - UTB/UTPA

Autosomes of Boophilus annulatus and B. microplus were compared using C- and G-bands to establish the degree of homology. Karyotypes of both species consisted of 20 autosomes and an XX:XO sex determination system with the X being the largest chromosome. All chromosomes of B. annulatus were acrocentric with heterochromatin limited to centromeric regions. The B. microplus karyotype was acrocentric with one band of noncentromeric heterochromatin occurring in three chromosome pairs. Interspecific comparisons indicated seven pairs of G-band homologous autosomes and three G-band homologous pairs when added interstitial heterochromatin was considered. The number three chromosome of both species showed variation in …

Go to article

A Phylogenetic Analysis Of Vertebrate And Invertebrate Notch-Related Genes, Eleanor M. Maine, James L. Lissemore, William T. Starmer Jan 1995

A Phylogenetic Analysis Of Vertebrate And Invertebrate Notch-Related Genes, Eleanor M. Maine, James L. Lissemore, William T. Starmer

Biology - All Scholarship

Members of the Notch gene family are thought to mediate inductive cell-cell interactions during develop ment of a wide variety of vertebrates and invertebrates. These genes encode transmembrane proteins that appear to act as receptors and contain three repeated sequence motifs. Two of these motifs (an epidermal growth factor like sequence and a cdc10/SW16/ankyrin sequence) have been found in a large number of unrelated proteins, while the third motif (a lin-12/Notch/glp-1 sequence) is unique to proteins of the Notch family. We present a phylogenetic analysis of 17 Notch-related genes from eight species that has implications as to the origins and …

Go to article

Genetic-Divergence Between The Wistar-Kyoto Rat And The Spontaneously Hypertensive Rat, Mark L. Johnson, Daniel Ely, Monte E. Turner May 1992

Genetic-Divergence Between The Wistar-Kyoto Rat And The Spontaneously Hypertensive Rat, Mark L. Johnson, Daniel Ely, Monte E. Turner

Biology Faculty Research

A method of restriction fragment length polymorphism (RFLP) analysis was used to estimate the amount of genetic divergence between the spontaneously hypertensive rat (SHR) strain and the Wistar-Kyoto (WKY) strain. DNA from each strain was digested with eight restriction endonucleases and hybridized with six single copy gene sequences. The number of hybridization bands in each digestion was used to estimate the total number of bases analyzed and RFLPs were scored as single mutations. Divergence was then estimated by dividing the number of mutations by the number of bases analyzed. In a total of 808 bases analyzed in WKY rats, a …

Go to article

Separate Sex-Influenced And Genetic Components In Spontaneously Hypertensive Rat Hypertension, Monte E. Turner, Mark L. Johnson, Daniel Ely Jun 1991

Separate Sex-Influenced And Genetic Components In Spontaneously Hypertensive Rat Hypertension, Monte E. Turner, Mark L. Johnson, Daniel Ely

Biology Faculty Research

Previous results from our laboratory indicated two major genetic components of spontaneously hypertensive rat (SHR) hypertension, an autosomal component and a Y chromosome component. Two new substrains, SHR/a and SHR/y, were developed using a series of backcrosses to isolate each of these components. The SHR/a substrain has the autosomal loci and X chromosome from the SHR strain and the Y chromosome from the Wistar-Kyoto (WKY) rat strain. The SHR/y substrain has only the Y chromosome from the SHR and autosomal loci and X chromosome from the WKY strain. Throughout these breeding programs parents were chosen at random without selection for …

Go to article

Isolation Of A Collagenase Cdna Clone And Measurement Of Changing Collagenase Mrna Levels During Induction In Rabbit Synovial Fibroblasts., Robert H. Gross, Lynn A. Sheldon, Colin F. Fletcher, Constance E. Brinckerhoff Apr 1984

Isolation Of A Collagenase Cdna Clone And Measurement Of Changing Collagenase Mrna Levels During Induction In Rabbit Synovial Fibroblasts., Robert H. Gross, Lynn A. Sheldon, Colin F. Fletcher, Constance E. Brinckerhoff

Dartmouth Scholarship

To facilitate our studies on the mechanisms controlling collagenase production at a molecular level in rabbit synovial fibroblasts, we have constructed a cDNA library using mRNAs isolated from cells induced with crystals of monosodium urate monohydrate. We have screened this library with cDNA probes made from induced and control mRNA populations. From among 30 clones that hybridized preferentially to the induced-cell probe, 4 contained collagenase sequences. The largest, a clone of 650 base pairs, was identified by its ability to hybrid select a mRNA that could be translated in a cell-free system into a product that was precipitable with monospecific …

Go to article

"Biological Determinism As A Social Weapon", Richard C. Lewontin Jan 1976

"Biological Determinism As A Social Weapon", Richard C. Lewontin

Special Collections: Oregon Public Speakers

No abstract provided.

Go to article

Proboscipedia, A Homeotic Mutant In Aedes Aegypti (L.) (Diptera: Culicidae), John Roach Roberts Jr. Jan 1973

Proboscipedia, A Homeotic Mutant In Aedes Aegypti (L.) (Diptera: Culicidae), John Roach Roberts Jr.

College of Graduate Studies: Theses & Dissertations (1964–2006)

No abstract provided.

Go to article

First Prev