Life Sciences Commons^™

An Outline Of A Theory Of The Constructional Constraints Governing Early Organismic Evolution, Winfried S. Peters, Bernd Herkner

Winfried S. Peters

This paper has no abstract; this is the first paragraph. The origin of life is one of the most fascinating biological enigmas (Dyson 1985, de Duve 1991). A multitude of hypotheses is available, ranging from the classical "primordial broth" (Haldane 1929) to the "genetic takeover" (Cairns-Smith 1982). Most of these models center on biochemical, metabolic, or genetic aspects. To our knowledge a comprehensive investigation into the mechanical constraints governing the early development of organismic constructions is not available to date. Attempting to close this gap, we here present an outline of a theory of the transformation of constructions in early …

Elimination Of Sequestered Material From The Gills Of Decapod Crustaceans., Gary Martin, Michael Quintero, Michael Quigley, Hovhannes Khosrovian

Gary Martin

Ink particles injected into the hemolymph of the American lobster (Homarus americanus), spiny lobster (Panulirus interruptus), crayfish (Procambarus clarkii), and ridgeback prawn (Sicyonia ingentis) were rapidly removed from circulation, and most were sequestered within nodules in the gills. The morphology of the gills and the nodules were examined from the time of injection until the following molt. The process by which ink was cleared from the gills was the same in all four species. Nodules formed within 10 min after injection and were composed of hemocytes loosely attached to one another and binding small quantities of ink. Within one week, …

A Homeostatic Set Point For Branching In Neurospora Crassa, Michael Watters, Christine Humphries, Ingrid De Vries, Anthony Griffiths

Michael Watters

The mechanisms responsible for controlling hyphal extension and branching are still poorly understood. We have investigated these processes by studying their dependence on temperature and nutrient concentration. Tip growth is highly responsive to temperature change, increasing linearly from 4 to 37 °C. Over this range of temperatures the branching pattern shows virtually no response. Likewise, varying nutrient concentration does not affect branch distribution. Colonies subjected to rapid extreme temperature downshifts (for example from 25 to 4°) display a strong and highly predictable branching response. There are three stages to this response. First there is an initial lag phase of growth …

Test Of Intron Predictions Reveals Novel Splice Sites, Alternatively Spliced Mrnas And New Introns In Meiotically Regulated Genes Of Yeast, Carrie A. Davis, Leslie Grate, Marc Spingola, Manuel Ares

Marc Spingola

Xenopus Laevis Gelatinase B (Xmmp-9): Development, Regeneration, And Wound Healing, Brian Walter, Maria Carinato, Jonathan Henry

Brian Walter

It has been argued that matrix metalloproteinases play important roles in cellular differentiation and regeneration in certain systems. While studying changes in gene expression associated with the phenomena of cornea/lens transdifferentiation ("lens regeneration"), which takes place in the larva of Xenopus laevis, we identified the Xenopus gelatinase B gene. The open reading frame is homologous to other gelatinase B genes identified in other species and encodes all of the domains characteristic of this protein. Xenopus gelatinase B (Xmmp-9) is first expressed during early tail-bud stages in a subset of mesodermal cells scattered throughout the body. Expression is also seen in …

Heterogeneity In Water Availability Alters Cellular Development And Hydraulic Conductivity Along Roots Of A Desert Succulent, Gretchen North, P. Nobel

Gretchen North

Plants of the desert succulent Agave deserti were grown in partitioned containers to determine whether heterogeneity in soil moisture leads to differences in cellular development and hydraulic conductivity along individual roots. Roots from containers with a dry distal compartment (furthest from the shoot), a wet middle compartment, and a dry proximal compartment had distal regions (including the root tips) that were more suberized and lignified in the endodermis and adjacent cell layers than were root regions from the wet middle compartment. Proximal root regions about 40 mm from the succulent shoot base were also relatively unsuberized, suggesting that both external …

The Effects Of Drought In The Solidago Altissima - Eurosta Solidaginis - Natural Enemy Complex: Population Dynamics, Local Extirpations, And Measures Of Selection Intensity Of Gall Size, D Sumerford, Warren Abrahamson, A Weis

Warren G. Abrahamson, II

No abstract provided.

Review Of The Cynipid Gall Wasps Of The Genus Loxaulus (Hymenoptera: Cynipidae) With Descriptions Of New Species, Warren Abrahamson

Warren G. Abrahamson, II

No abstract provided.

Adaptive Amplification, An Inducible Chromosomal Instability Mechanism, P. Hastings, H. Bull, Jennifer Kowalski, S. Rosenberg

Jennifer Kowalski

Adaptive mutation is an induced response to environmental stress in which mutation rates rise, producing permanent genetic changes that can adapt cells to stress. This contrasts with neo-Darwinian views of genetic change rates blind to environmental conditions. DNA amplification is a flexible, reversible genomic change that has long been postulated to be adaptive. We report the discovery of adaptive amplification at the lac operon in Escherichia coli. Additionally, we find that adaptive amplification is separate from, and does not lead to, adaptive point mutation. This contradicts a prevailing alternative hypothesis whereby adaptive mutation is normal mutability in amplified DNA. Instead, …

Review Of The Cynipid Gall Wasps Of The Genus Loxaulus (Hymenoptera Cynipidae) With Descriptions Of New Species, G. Melika, Warren Abrahamson

Warren G. Abrahamson, II

No abstract provided.

Historical Review And Current State Of The World Generic Classification Of Oak Galls (Hymenoptera: Cynipidae: Cynipini, Warren Abrahamson, G. Melika

Warren G. Abrahamson, II

No abstract provided.

Virulence Factors From Pseudomonas Aeruginosa Increase Lung Epithelial Permeability, Ali Azghani, E. J. Miller, Barry T. Peterson

Ali Azghani

Photobehavior Of The Harpacticoid Copepod Tigriopus Californicus And The Fine Structure Of Its Nauplius Eye., Gary G. Martin

Gary Martin

Members of Tigriopus californicus, and harpacticoid copepod, live in small, shallow tidepools in the upper spray zone where they cannot avoid the full effect of visible and ultraviolet (UV) radiation. Field experiments using ambient light show that individuals of T. californicus aggregate in areas of lower radiation at midday, yet have no preference between areas exposed only to photosynthetically active radiation (PAR) or shade, but aggregate in the shaded portion of a tank when exposed to UV_B. Light detection in T. californicus is presumably by the nauplius eye, which is described at the histoligical and iltrastructural levels. Microvilli of the …

Biospheric Cooling And The Emergence Of Intelligence, David Schwartzman, George Middendorf

George Middendorf

Phenotypic Effects Of Leptin In An Ectotherm: A New Tool To Study The Evolution Of Life Histories And Endothermy?, Richard L. Londraville, Michelle L. Balk, Peter H. Niewiarowski

Dr. Peter H. Niewiarowski

Leptin is a hormone that regulates energy expenditure and body mass in mammals, and it has attracted considerable attention because of its potential in treating human obesity. Comprehensive data from both pathological and non-pathological systems strongly support a role for leptin in regulating energy metabolism, in thermoregulation and in regulating the onset of puberty. We report here that daily injections of recombinant murine leptin in fence lizards (Sceloporus undulatus) produce phenotypic effects similar to those observed when leptin injections are given to mice, Lizards injected with leptin had body temperatures 0.6 degrees C higher, ate 30 % less food and …

Phenotypic Effects Of Leptin In An Ectotherm: A New Tool To Study The Evolution Of Life Histories And Endothermy?, Richard L. Londraville, Michelle L. Balk, Peter H. Niewiarowski

Richard L. Londraville

Leptin is a hormone that regulates energy expenditure and body mass in mammals, and it has attracted considerable attention because of its potential in treating human obesity. Comprehensive data from both pathological and non-pathological systems strongly support a role for leptin in regulating energy metabolism, in thermoregulation and in regulating the onset of puberty. We report here that daily injections of recombinant murine leptin in fence lizards (Sceloporus undulatus) produce phenotypic effects similar to those observed when leptin injections are given to mice, Lizards injected with leptin had body temperatures 0.6 degrees C higher, ate 30 % less food and …

Temperature-Dependent Parental Investment In The Giant Waterbug Belostoma Flumineum (Heteroptera: Belostomatidae), Scott Kight

Scott Kight

A Viable Ubiquitin-Activating Enzyme Mutant For Evaluating Ubiquitin System Function In Saccharomyces Cerevisiae, Rob Swanson, Mark Hochstrasser

Rob Swanson

Ligation of proteins to ubiquitin requires activation of ubiquitin by E1, the ubiquitin-activating enzyme. Mutant alleles of E1 in mammalian cells have been crucial for dissecting the contribution of the ubiquitin system to cell function. Comparable mutants have been unavailable for Saccharomyces cerevisiae. Here we describe the isolation and characterization of a hypomorphic allele of S. cerevisiae E1. Protein modification by ubiquitin is strongly impaired in the mutant, inhibiting degradation of ubiquitin^proteasome pathway substrates as well as ubiquitin-dependent but proteasome-independent degradation of membrane receptors. This allele will be a useful tool for evaluating the ubiquitin-dependence of cellular processes in yeast, …

Reflexive Autopoietic Systems Theory, Kent D. Palmer

Kent D. Palmer

Exploring the Meta-systems of Emergent Worlds

Bird Distribution And Conservation In The Ailao Mountains, Yunnan, China, Zhijun Wang, Chris Carpenter, Stephen S. Young

Stephen Young