• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 24
  • 8
  • 4
  • 3
  • 2
  • 1
  • Tagged with
  • 59
  • 13
  • 10
  • 9
  • 7
  • 7
  • 6
  • 6
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

A Quantitative Evaluation of Fish Passage Options for the Dam on the Black Sturgeon River

Smyth, Eric 16 September 2011 (has links)
Humans domesticate nature to suit their needs. Such alterations can create trade-offs between human needs and ecosystem services. Quantification of these trade-offs is needed to domesticate nature more wisely. My thesis quantifies tradeoffs between invasive species control and the rehabilitation and protection of native fishes associated with the preservation and relocation of the dam on the Black Sturgeon River on the north shore of Lake Superior. I evaluated the trade-offs in terms of five performance measures: abundances of walleye, sea lamprey, lake sturgeon, and northern brook lamprey, and financial cost. I found that the management of the Black Sturgeon River would depend on value judgments because of the high complexity and uncertainty of the system. The analysis of the Black Sturgeon River could be an example of how to evaluate the trade-offs between invasive species control and native fish passage and be used for similar systems which share this trade-off.
22

A stable isotope analysis of food web structure in Lake Superior

Harvey, Christopher James. January 1900 (has links)
Thesis (Ph. D.)--University of Wisconsin, Madison, 2001. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
23

Functional genomics reveals molecular programs associated with recovery from spinal cord injury in lampreys

Herman, Paige 11 July 2017 (has links)
The lamprey is a basal vertebrate that achieves spontaneous functional recovery after complete spinal cord transection over a stereotypical period of 12 weeks. Despite anatomical, physiological, and behavioral data on spinal cord regeneration in lamprey, the molecular mechanisms underlying this capacity are largely unknown. In this study, next generation RNA-sequencing (RNA-Seq) of the brain and injury site within the spinal cord was used to determine and compare transcriptional profiles of uninjured and recovered lampreys at 12 weeks after spinal cord injury (SCI), when normal swimming behavior is achieved. The objective of this study was to determine if recovered animals had a significantly different transcriptional program than uninjured animals. Significant differences in gene expression were observed, with 1468 and 1033 differentially expressed genes in the spinal cord and brain respectively. Leveraging functional data for mammalian homologs of differentially expressed genes, several conserved transcription factors and molecular pathways in both uninjured and injured animals were identified. Gene expression patterns associated with functional recovery in lampreys may be useful in guiding studies aimed at modulating mammalian responses to spinal cord injury, and promoting functional recovery in species with less spontaneous regenerative potential. / 2019-07-11T00:00:00Z
24

Mechanisms of elasticity in elastic proteins

Green, Ellen Marie January 2012 (has links)
This thesis investigates the mechanical properties of the elastic proteins isolated by cyanogen bromide digestion from lamprey cartilages and compares them with the mammalian protein, elastin. Thermomechanical testing and measurements of the effects of hydrophobic solvents on mechanics are used to determine the energetic and entropic contributions to the mechanical properties and the role of solvent interactions. Raman microspectrometry is shown to be a valuable tool in determining the secondary structure of the proteins, their interactions with water and molecular-level effects of mechanical strain. The supramolecular structure of the proteins matrices are investigated using nonlinear microscopy and X-ray diffraction. The mechanical properties of fibrous elastin agreed with those previously reported with elastic moduli in the region of 0.2-0.4 MPa. Elastic moduli decrease by approximately 25% with increased temperature, which was accompanied by a small decrease in hysteresis loss. In agreement with earlier findings, an entropic mechanism of elasticity became dominant only at high temperatures with a major contribution from interactions with solvent water. The lamprey proteins can be divided into two broad groups, the 'soft' branchial and pericardial cartilages resembling elastin, with linear stress-strain behaviour over a range of strains, elastic moduli in the range 0.13 MPa to 0.35 MPa, breaking strains of up to 50% and low hysteresis. Annular and piston proteins showed a very different response having much higher elastic moduli (0.27 MPa to 0.75 MPa), higher breaking strains and large hysteresis. Similarities between elastin and the lamprey matrix proteins extended to their thermomechanical behaviour with a decrease in elastic moduli and a drive towards entropic elasticity at high temperatures, although the annulus and piston were less thermally stable. Raman spectroscopy was able to detect differences between the various proteins and between elastin fibres and fragmentation products. Although no vibrational modes associated with cross-linking of the fibres could be identified, the secondary structure of dehydrated fibrous elastin was significantly different from \alpha -elastin. The former differed from previous experimental measurements, but was close to the theoretical predictions with 36% \beta -structures, 46% unordered and 18% \alpha -helix. \alpha -Elastin contained 29% \beta -structures, 53% unordered and 18% \alpha -helix. Strains of up to 60% in ligament fibre bundles resulted in no significant shifts in peak positions or in secondary structure. Polarization measurements revealed that the peptide bonds and several of the bulky side-chains re-orientated closer to the fibre axis with strain. Heating nuchal elastin fibres to 60^{\circ} C to increase the energetic component of the elasticity was associated with a 30% increase in the proportion of \beta -structures in the amide I band, a 50% increase in the amide III band, and a 50% reduction in the signal from bound water. The Raman spectra of the lamprey matrix proteins are similar both to each other and when compared to fibrous elastin. Only small differences could be detected in side-chain modes consistent with reported biochemical differences. Decomposition of the amide I band indicated that the secondary structures were also very similar to that of elastin, with a preponderance of unordered structures which probably confer the high degree of conformational flexibility necessary for entropy elasticity. Piston and annular proteins, like elastin, showed a strong interaction with water, suggesting a greater role of hydrophobic interactions in their mechanics compared to the branchial and pericardial proteins. Elastin is well known to exhibit autofluorescence. However, only the branchial protein has been reported to autofluoresce. This study shows that all four lamprey matrix proteins investigated exhibit strong autofluorescence which was subsequently exploited to image these tissues using multiphoton microscopy. Microscopic investigations revealed that the architecture of lamprey proteins differ from that of elastin. Nuchal elastin forms bundles of fibres running predominantly parallel to the direction of applied force. The arrangement in lamprey cartilage is very different forming honeycomb structures, which in the case of annular and piston cartilages, is surrounded by a dense sheath of matrix material. Dye injections revealed that the branchial and pericardial form open systems whereas in piston and annular cartilages a closed system exists. These variations in architecture are reflected in their different mechanical properties and in vivo functions.
25

Ovarian differentiation in an ancient vertebrate: timing, candidate gene expression, and global gene expression in parasitic and non-parasitic lampreys

Spice, Erin 22 August 2013 (has links)
Lamprey adults may be parasitic or non-parasitic, but the genetic basis of life history type is unknown. Although external differences between types are not apparent until metamorphosis, previous studies have suggested histological differences during ovarian differentiation. This study examined potential differences between parasitic chestnut lamprey Ichthyomyzon castaneus and non-parasitic northern brook lamprey I. fossor before, during, and after ovarian differentiation, using histological examination of the gonad, quantitative reverse-transcriptase PCR, and RNA sequencing. There were no observable differences in the timing or nature of ovarian differentiation. However, there was evidence of differential expression of individual genes associated with growth, apoptosis, and fecundity and of sets of genes associated with energy and lipid metabolism. The sequence resources developed in this project will be useful for future examination of the genetic basis of lamprey life history type and of the genes controlling sex differentiation in these ancient vertebrates.
26

Ovarian differentiation in an ancient vertebrate: timing, candidate gene expression, and global gene expression in parasitic and non-parasitic lampreys

Spice, Erin 22 August 2013 (has links)
Lamprey adults may be parasitic or non-parasitic, but the genetic basis of life history type is unknown. Although external differences between types are not apparent until metamorphosis, previous studies have suggested histological differences during ovarian differentiation. This study examined potential differences between parasitic chestnut lamprey Ichthyomyzon castaneus and non-parasitic northern brook lamprey I. fossor before, during, and after ovarian differentiation, using histological examination of the gonad, quantitative reverse-transcriptase PCR, and RNA sequencing. There were no observable differences in the timing or nature of ovarian differentiation. However, there was evidence of differential expression of individual genes associated with growth, apoptosis, and fecundity and of sets of genes associated with energy and lipid metabolism. The sequence resources developed in this project will be useful for future examination of the genetic basis of lamprey life history type and of the genes controlling sex differentiation in these ancient vertebrates.
27

Cloning and expression of a corticoid receptor in the sea lamprey (Petromyzon marinus)

Yeh, Chu-Yin. January 2008 (has links)
Thesis (M.S.)--Michigan State University. Dept. of Physiology, 2008. / "Committee members, Weiming Li, Richard Miksicek, and Cheryl Sisk"--Acknowledgments. Title from PDF t.p. (viewed on Aug. 4, 2009) Includes bibliographical references (p. 51-54). Also issued in print.
28

Morfogeneze orálního skeletu mihule ve vztahu k evoluci čelistí / Morfogeneze orálního skeletu mihule ve vztahu k evoluci čelistí

Romášek, Marek January 2012 (has links)
4 Neural crest-derived cellular cartilage is one of the defining characteristics of vertebrates. Elaboration of this tissue and its patterning allowed the evolution of jaws in the gnathostome lineage. Together these hallmarks helped jawed vertebrates become one of the dominant taxons in the animal kingdom. Lampreys, as basal jawless vertebrates, lie at a unique phylogenetic position that makes them ideal organisms for the study of evolution of vertebrate/gnathostome novelties. Larval lampreys possess a special oral skeleton composed of a tissue related to cartilage, termed mucocartilage. Despite considerable attention that has been paid to the evolutionary significance of mucocartilage, it is not yet clear, how this unique feature arises in development and to what extent it is homologous to gnathostome jaws. In this study, the development of oro-pharyngeal region was analyzed in the sea lamprey Petromyzon marinus. SEM imaging revealed shaping and topographic relationships of embryonic tissues, detailed plastic histology coupled with expression analyses of several molecular markers were used to describe origin, histogenesis and morphogenesis of mucocartilage. Furthermore, genetic regulation of the tissue was investigated in order to identify its unique or shared features. Mucocartilage is seen to...
29

Purification and Identification of Cell Surface Antigens using Lamprey Monoclonal Antibodies

Shabab, Ali 20 November 2013 (has links)
The evolutionary distance of lampreys from humans in conjunction with their distinct antibody architecture is profound. Thus, lampreys may provide antibodies with specificity for antigens unrecognized by conventional mammalian antibodies. This study investigates lamprey based monoclonal variable lymphocyte receptor antibodies (VLRs) for purifying and identifying an antigen by tandem mass spectrometry. VLRs specific for clinically relevant cell populations were isolated. Subsequently, utilizing intrinsic VLR affinity, with or without covalent cross-linking molecules, for immunoprecipitating VLR protein antigens was tested. In one case, CD5 glycoprotein from Jurkat T cells was purified by a VLR; the antigen was identified by tandem mass spectrometry. Antibody specificity was validated by western blotting and flow cytometry. Furthermore, VLR binding to CD5 required multimerization of the antibody, indicating the individual VLR units likely bind antigen with low affinity. The study provides ‘proof of concept’ for human biomarker identification using novel lamprey monoclonal antibodies.
30

Comparative Analysis of the Anatomy of the Myxinoidea and the Ancestry of Early Vertebrate Lineages

Miyashita, Tetsuto Unknown Date
No description available.

Page generated in 0.0444 seconds