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

Life Sciences Commons™

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

Biology

Selected Works

2002

Articles 1 - 26 of 26

Full-Text Articles in Life Sciences

Syd-1, A Presynaptic Protein With Pdz, C2 And Rhogap-Like Domains, Specifies Axon Identity In C. Elegans, Steven Hallam, Alexandr Goncharov, Jason Mcewen, Renee Baran, Yishi Jin Oct 2002

Syd-1, A Presynaptic Protein With Pdz, C2 And Rhogap-Like Domains, Specifies Axon Identity In C. Elegans, Steven Hallam, Alexandr Goncharov, Jason Mcewen, Renee Baran, Yishi Jin

Renee Baran

Axons are defined by the presence of presynaptic specializations at specific locations. We show here that loss-of-function mutations in the C. elegans gene syd-1 cause presynaptic specializations to form in the dendritic processes of GABA-expressing motor neurons during initial differentiation. At a later developmental stage, however, syd-1 is not required for the polarity respecification of a subset of these neurons. The SYD-1 protein contains PDZ, C2 and rho–GTPase activating protein (GAP)-like domains, and is localized to presynaptic terminals in mature neurons. A truncated SYD-1 that lacks the rhoGAP domain interferes with neurite outgrowth and guidance. Our data indicate that syd-1 …

Go to article

Pseudomonas Aeruginosa Elastase Stimulates Erk Signaling Pathway And Enhances Il- 8 Production By Alveolar Epithelial Cells In Culture, Ali Azghani, J. W. Baker, S. Shetty, E. J. Miller, G. J. Bhat Sep 2002

Pseudomonas Aeruginosa Elastase Stimulates Erk Signaling Pathway And Enhances Il- 8 Production By Alveolar Epithelial Cells In Culture, Ali Azghani, J. W. Baker, S. Shetty, E. J. Miller, G. J. Bhat

Ali Azghani

Objective and design: Bacterial products as well as the host airway inflammatory responses contribute to the pathogenesis of Pseudomonas infections. We sought to determine if Pseudomonas elastase (PE) induces mitogen-activated protein (MAP) kinase activity in association with interleukin-8 (IL-8) production by alveolar epithelial cells.¶Methods: We utilized Western blot analysis to detect phosphorylation of signaling intermediates and ELISA was used to measure IL-8 production.¶Results: We found that PE induces phosphorylation of the extracellular signal-regulated (ERK1/2) proteins of the MAPK pathway in A549 epithelial cells. Similar results were obtained using primary cultures of rabbit alveolar type II epithelial cells. PE also enhanced …

Go to article

A Mathematical Model Of Bacterial Aerotaxis, Borbala Mazzag, Alex Mogilner Sep 2002

A Mathematical Model Of Bacterial Aerotaxis, Borbala Mazzag, Alex Mogilner

Borbala Mazzag

No abstract provided.

Go to article

Characterizing Gene Expression During Lens Formation In Xenopus Laevis: Evaluating The Model For Embryonic Lens Induction, Brian Walter, Jonathan Henry, Maria Carinato, Jonathan Schaefer, Adam Wolfe, Brian Walter, Kimberly Perry, Tricia Elbl May 2002

Characterizing Gene Expression During Lens Formation In Xenopus Laevis: Evaluating The Model For Embryonic Lens Induction, Brian Walter, Jonathan Henry, Maria Carinato, Jonathan Schaefer, Adam Wolfe, Brian Walter, Kimberly Perry, Tricia Elbl

Brian Walter

Few directed searches have been undertaken to identify the genes involved in vertebrate lens formation. In the frog Xenopus, the larval cornea can undergo a process of transdifferentiation to form a new lens once the original lens is removed. Based on preliminary evidence, we have shown that this process shares many elements of a common molecular/genetic pathway to that involved in embryonic lens development. A subtracted cDNA library, enriched for genes expressed during cornea-lens transdifferentiation, was prepared. The similarities/identities of specific clones isolated from the subtracted cDNA library define an expression profile of cells undergoing cornea-lens transdifferentiation ("lens regeneration") and …

Go to article

Caudal Spotting In The Beacon Fish (Hemigrammus Ocellifer Characidae), Jack Frankel May 2002

Caudal Spotting In The Beacon Fish (Hemigrammus Ocellifer Characidae), Jack Frankel

Jack Frankel

The beacon fish (Hemigrammus ocellifer) exhibits two phenotypes associated with spotting at the base of the caudal fin, with fish either possessing (H. o. ocellifer) or lacking (H. o. falsus) a prominent red spot in this region. Segregation patterns observed from the progenies of 15 different crosses support a hypothesis that caudal spotting in this species is controlled by a single gene with two alleles, for which the caudal spotting allele is completely dominant.

Go to article

Role Of A Heterotrimeric G Protein In Regulation Of Arabidopsis Seed Germination, Hemayet Ullah, Jin-Gui Chen, Shucai Wang, Alan M. Jones May 2002

Role Of A Heterotrimeric G Protein In Regulation Of Arabidopsis Seed Germination, Hemayet Ullah, Jin-Gui Chen, Shucai Wang, Alan M. Jones

Hemayet Ullah

Seed germination is regulated by many signals. We investigated the possible involvement of a heterotrimeric G protein complex in this signal regulation. Seeds that carry a protein null mutation in the gene encoding the alpha subunit of the G protein in Arabidopsis (GPA1) are 100-fold less responsive to gibberellic acid (GA), have increased sensitivity to high levels of Glc, and have a near-wild-type germination response to abscisic acid and ethylene, indicating that GPA1 does not directly couple these signals in germination control. Seeds ectopically expressing GPA1 are at least a million-fold more responsive to GA, yet still require GA for …

Go to article

Getting A Grip On Liprins, Renee Baran, Yishi Jin Mar 2002

Getting A Grip On Liprins, Renee Baran, Yishi Jin

Renee Baran

Two papers in this issue of Neuron add a new dimension to our understanding of liprin and LAR RPTP function during synapse formation. Kaufmann et al. (2002) present evidence that Dliprin-α interacts with Dlar to regulate presynaptic morphogenesis of the Drosophila neuromuscular junction. Wyszynski et al. (2002) demonstrate that mammalian liprin-α1 forms a complex with the PDZ protein GRIP and LAR in both pre- and postsynaptic compartments of hippocampal neurons and is required for the clustering of the GluR2 glutamate receptor in dendritic spines.

Go to article

The Nmda Receptor M3 Segment Is A Conserved Transduction Element Coupling Ligand Binding To Channel Opening, Kevin S. Jones, Hendrika M A Vandongen, Antonius M. Vandongen Feb 2002

The Nmda Receptor M3 Segment Is A Conserved Transduction Element Coupling Ligand Binding To Channel Opening, Kevin S. Jones, Hendrika M A Vandongen, Antonius M. Vandongen

Kevin Jones

Ion channels alternate stochastically between two functional states, open and closed. This gating behavior is controlled by membrane potential or by the binding of neurotransmitters in voltage- and ligand-gated channels, respectively. Although much progress has been made in defining the structure and function of the ligand-binding cores and the voltage sensors, how these domains couple to channel opening remains poorly understood. Here we show that the M3 transmembrane segments of the NMDA receptor allosterically interact with both the ligand-binding cores and the channel gate. It is proposed that M3 functions as a transduction element whose conformational change couples ligand binding …

Go to article

Captive Double-Crested Cormorant Phalacrocorax Auritus Predation On Channel Catfish Ictalurus Punctatus Fingerlings And Its Influence On Single-Batch Cropping Production, Brian S. Dorr Feb 2002

Captive Double-Crested Cormorant Phalacrocorax Auritus Predation On Channel Catfish Ictalurus Punctatus Fingerlings And Its Influence On Single-Batch Cropping Production, Brian S. Dorr

Brian S Dorr

Abstract.-We studied the effect of captive double-crested cormorant Phalacrocorax auritus predation on channel catfish Ictalurus punctatus inventories from research ponds with and without alternative prey during the years 1998-2000. In 1998, predation by two groups of captive cormorants on ponds without alternative prey produced inventory reductions relative to a control pond that were equivalent to 10.2 (516 g) and I 0.5 (608 g) catfish/bird per d. In 1999 and 2000 individual cormorants foraging on 0.02-ha pond halves for I 0 d (500 cormorant d/ha) stocked with both catfish and golden shiners Notemigonus crysoleucas produced inventory reductions at harvest (7.5 mo …

Go to article

Spiroplasmas: Evolution, Adaptation And Diversity, Gail E. Gasparich Feb 2002

Spiroplasmas: Evolution, Adaptation And Diversity, Gail E. Gasparich

Gail Gasparich

Since its designation as a separate genus some 30 years ago, Spiroplasmas have been well documented in a wide range of hosts and as the causative agent of several plant and insect diseases. One major area of research is the continued identification and taxonomical characterization of new Spiroplasma sp. combined with a determination of phylogenetic relationships among the various Spiroplasma sp. and between the Spiroplasmas and other members of the Mollicutes and Eubacteria. Although most phylogenetic analyses have been dependent on 16S rDNA sequence data, progress in two Spiroplasma sp. genome sequencing projects will provide new genomic regions for comparative …

Go to article

Costs Of Reproduction In The Terrestrial Isopod Porcellio Laevis Latreille (Isopoda: Oniscidea): Brood-Bearing And Locomotion, Scott Kight Jan 2002

Costs Of Reproduction In The Terrestrial Isopod Porcellio Laevis Latreille (Isopoda: Oniscidea): Brood-Bearing And Locomotion, Scott Kight

Scott Kight

Female terrestrial isopods carry eggs and young throughout early development, a habit that places constraints on reproductive success. One such constraint is impaired locomotion during the brooding period. Brooding and non-brooding females were subjected to a negative-phototaxis experiment in which females moved away from a light source along a graduated surface. In both groups, velocity was positively and significantly correlated with distance traveled. Velocity and distance were also significantly associated with the physical dimensions of the exoskelton: larger females moved greater distances at faster speeds. Non-brooding females, however, moved significantly farther at significantly greater velocities than brooding females, suggesting that …

Go to article

Biological Implications Of The Weibull And Gompertz Models Of Aging, Robert Ricklefs, Alex Scheuerlein Jan 2002

Biological Implications Of The Weibull And Gompertz Models Of Aging, Robert Ricklefs, Alex Scheuerlein

Robert Ricklefs

Gompertz and Weibull functions imply contrasting biological causes of demographic aging. The terms describing increasing mortality with age are multiplicative and additive, respectively, which could result from an increase in the vulnerability of individuals to extrinsic causes in the Gompertz model and the predominance of intrinsic causes at older ages in the Weibull model. Experiments that manipulate extrinsic mortality can distinguish these biological models. To facilitate analyses of experimental data, we defined a single index for the rate of aging (ω) for the Weibull and Gompertz functions. Each function described the increase in aging-related mortality in simulated ages at death …

Go to article

Life History Trade-Offs And Phenotypic Plasticity In The Reproduction Of Galápagos Lava Lizards (Microlophus Delanonis), Mark Jordan, Howard Snell Dec 2001

Life History Trade-Offs And Phenotypic Plasticity In The Reproduction Of Galápagos Lava Lizards (Microlophus Delanonis), Mark Jordan, Howard Snell

Mark A. Jordan

No abstract provided.

Go to article

Root Deployment And Shoot Growth For Two Desert Species In Response To Soil Rockiness, P. Martre, Gretchen North, E. Bobich, P. Nobel Dec 2001

Root Deployment And Shoot Growth For Two Desert Species In Response To Soil Rockiness, P. Martre, Gretchen North, E. Bobich, P. Nobel

Gretchen North

Soil texture, as well as the presence of rocks, can determine the water status, growth, and distribution of plants in arid environments. The effects of soil rockiness and soil particle size distribution on shoot and root growth, root system size, rooting depth, and water relations were therefore investigated for the Crassulacean acid metabolism leaf succulent Agave deserti and the C4 bunchgrass Pleuraphis rigida after precipitation events during the summer and winter/spring rainfall periods in the northwestern Sonoran Desert. The soils at the field site varied from sandy (<3% rocks by volume) to rocky (up to 35% rocks), with greater …

Go to article

Plasma Membrane Aquaporins Play A Significant Role During Recovery From Water Deficit, P. Martre, R. Morillon, F. Barrieu, Gretchen North, P. Nobel, M. Chrispeels Dec 2001

Plasma Membrane Aquaporins Play A Significant Role During Recovery From Water Deficit, P. Martre, R. Morillon, F. Barrieu, Gretchen North, P. Nobel, M. Chrispeels

Gretchen North

The role of plasma membrane aquaporins (PIPs) in water relations of Arabidopsis was studied by examining plants with reduced expression of PIP1 and PIP2 aquaporins, produced by crossing two different antisense lines. Compared with controls, the double antisense (dAS) plants had reduced amounts of PIP1 and PIP2 aquaporins, and the osmotic hydraulic conductivity of isolated root and leaf protoplasts was reduced 5- to 30-fold. The dAS plants had a 3-fold decrease in the root hydraulic conductivity expressed on a root dry mass basis, but a compensating 2.5-fold increase in the root to leaf dry mass ratio. The leaf hydraulic conductance …

Go to article

Stem Turnover In The Clonal Scrub Oak, Quercus Inopina, Warren Abrahamson, A.F. Johnson Dec 2001

Stem Turnover In The Clonal Scrub Oak, Quercus Inopina, Warren Abrahamson, A.F. Johnson

Warren G. Abrahamson, II

No abstract provided.

Go to article

Relation Of Ramet Size To Acorn Production In Five Oak Species Of Xeric Upland Habitats In South-Central Florida, Warren Abrahamson, J.N. Layne Dec 2001

Relation Of Ramet Size To Acorn Production In Five Oak Species Of Xeric Upland Habitats In South-Central Florida, Warren Abrahamson, J.N. Layne

Warren G. Abrahamson, II

No abstract provided.

Go to article

Isolation And Characterization Of Microsatellite Loci From Galápagos Lava Lizards (Microlophus Spp.), Mark Jordan, Robert Hammond, Howard Snell, Heidi Snell, William Jordan Dec 2001

Isolation And Characterization Of Microsatellite Loci From Galápagos Lava Lizards (Microlophus Spp.), Mark Jordan, Robert Hammond, Howard Snell, Heidi Snell, William Jordan

Mark A. Jordan

No abstract provided.

Go to article

Persistent Palmettos: Effects Of The 2000-2001 Drought On Serenoa Repens And Sabal Etonia, Warren Abrahamson, C.R. Abrahamson Dec 2001

Persistent Palmettos: Effects Of The 2000-2001 Drought On Serenoa Repens And Sabal Etonia, Warren Abrahamson, C.R. Abrahamson

Warren G. Abrahamson, II

No abstract provided.

Go to article

Review Of The World Genera Of Oak Cynipid Wasps (Hymenoptera: Cynipidae, Cynipini), Warren Abrahamson, G. Melika Dec 2001

Review Of The World Genera Of Oak Cynipid Wasps (Hymenoptera: Cynipidae, Cynipini), Warren Abrahamson, G. Melika

Warren G. Abrahamson, II

No abstract provided.

Go to article

Post-Fire Recovery Of Acorn Production By Four Oak Species In Southern Ridge Sandhill Association In South-Central Florida, Warren Abrahamson, J.N. Layne Dec 2001

Post-Fire Recovery Of Acorn Production By Four Oak Species In Southern Ridge Sandhill Association In South-Central Florida, Warren Abrahamson, J.N. Layne

Warren G. Abrahamson, II

No abstract provided.

Go to article

Mathematical Models In Biology, Borbala Mazzag Dec 2001

Mathematical Models In Biology, Borbala Mazzag

Borbala Mazzag

No abstract provided.

Go to article

Fish Production Of A Temperate Artificial Reef Based On The Density Of Embiotocids (Teleostei: Perciformes), Daniel J. Pondella Ii, John S. Stephens Jr., Matthew T. Craig Dec 2001

Fish Production Of A Temperate Artificial Reef Based On The Density Of Embiotocids (Teleostei: Perciformes), Daniel J. Pondella Ii, John S. Stephens Jr., Matthew T. Craig

Daniel Pondella

The abundance of two embiotocids (Embiotoca jacksoni and Rhacochilus vacca) was surveyed continually from 1974 to 1998 on the breakwaters comprising King Harbor in Redondo Beach, California, and a nearby natural rocky-reef as a reference. Embiotocids provide an interesting model for reef-fish production because they are viviparous and their entire ontogeny can be observed on the reefs. We deduce that the two reef populations of both species were stable at their carrying capacity. This carrying capacity was greater in King Harbor throughout the study. We also report a linear decline in survival of juveniles of both species over the 25-year …

Go to article

A Long Way From Home: Transatlantic Sea Star Migration, William Jaeckle, Paul Kehle Dec 2001

A Long Way From Home: Transatlantic Sea Star Migration, William Jaeckle, Paul Kehle

William Jaeckle

For a marine biologist strolling along the eastern coast of South America, finding some sea stars (popularly called starfish, and technically members of the class Asteroidea of the phylum Echinodermata) is not all that unusual. However, when closer inspection reveals the sea stars to be ones that are also found on the shores of the western coast of Africa, the marine biologist now faces an interesting question: How did these sea stars come to be so far from home? Originally published in Consortiumand used with permission.

Go to article

Exotic Aquatic: The Culturing Of Native Vs. Exotic Species: A Dilemma, Paula Furey Dec 2001

Exotic Aquatic: The Culturing Of Native Vs. Exotic Species: A Dilemma, Paula Furey

Paula Furey

No abstract provided.

Go to article

Larval Productivity Of A Mature Artificial Reef: The Ichthyoplankton Of King Harbor, California, 1974–1997, John Stephens Jr, Daniel Pondella Ii Dec 2001

Larval Productivity Of A Mature Artificial Reef: The Ichthyoplankton Of King Harbor, California, 1974–1997, John Stephens Jr, Daniel Pondella Ii

Daniel Pondella

Do artificial reefs serve as productive marine fish habitats (sources) or do fish assemblages of such reefs contribute little to the gene pool of succeeding generations (sinks)? Using data from a 24-year study of the breakwater at King Harbor (California, USA), annual densities of reef fish larvae were compared with densities observed elsewhere in the Southern California Bight. Larval production at King Harbor has decreased over the study period, as has the size of the fish assemblage. Both declines may be related to recorded increases in water temperature. Larval densities from similar water depths (0–15 m) throughout the bight vary …

Go to article