Filamentous actin is localized in cells using rhodaminyl-phalloidin (RPHD) after p-formaldehyde fixation and lysolecithin permeabilization. The surface of unfertilized Arbacia punctulata and Lytechinus variegatus eggs have numerous punctate fluorescence sites, indicating the presence of actin oligomers or polymers. Within thirty seconds of insemination a fertilization cone is detected as an erect structure on the surface of the egg. The fertilization cone grows to a maximum size by 8 to 9 minutes and is resorbed by 16 minutes after insemination. Fluorescent fibers are found on the surface of eggs by 10 minutes after insemination as a result of a burst in actin polymerization. Elongated microfilaments persist through cytokinesis. At cytokinesis a narrow bundle of microfilaments, the contractile ring, is found in the cleavage furrow. / Latrunculin-A (Lat-A), a recently identified inhibitor of microfilaments, reduces the viscosity of actin gels formed from sea urchin egg homogenates. An acrosomal process is not formed in sea urchin sperm treated with Lat-A, although, the acrosomal vesicle contents are released. Unpacking of the Limulus (horseshoe crab) sperm pre-assembled acrosomal process is not affected by Lat-A, indicating filaments not undergoing subunit exchange are unaffected by Lat-A. / To determine if cyclic nucleotides regulate cytoskeletal activity, radioimmune assays were performed to measure cyclic nucleotide levels. cAMP and cGMP were found to fluctuate in cycles similar to cytoskeletal activity in sea urchin eggs. Treatment with isobutylmethyl xanthine, a phosphodiesterase inhibitor, resulted in elevated levels of cAMP and cGMP and division did not occur. However, treatments with another phosphodiesterase inhibitor, Ro 20 1724/1, or cholera toxin, or cyclic nucleotide analogues, resulted in elevated cAMP and cGMP levels, but did not affect normal development. Therefore, in these experiments the levels of cyclic nucleotides in eggs do not appear to regulate motion directly. / Source: Dissertation Abstracts International, Volume: 47-06, Section: B, page: 2263. / Thesis (Ph.D.)--The Florida State University, 1986.

A "single cell" approach was applied to the study of visual pigment bleaching in rod photoreceptors. After intact toad eyes were exposed to light, rod photoreceptors were removed and studied microspectrophotometrically. Under "bleaching only" conditions, the axial gradients of rhodopsin remaining were observed to change, as a function of the number of rhodopsins bleached, and the wavelength of the illuminant. These gradients showed good agreement to a proposed model. The derivation of this model was based upon some of the known properties of visual pigments and their arrangement within the rod outer segment. / Extremely bright, brief flashes of white light are known to cause photoreversal in the eyes of living animals. Using this kind of light, the intracellular distributions of rhodopsin remaining in the rod outer segments were shown to resemble those obtained after nonphotoreversing illumination. Subtle differences were detectable, though. / Physiological mechanisms for pigment regeneration exist in vertebrate eyes. Rhodopsin distributions were studied in toads illuminated for long periods of time, where bleaching and regeneration were allowed to occur together. Using either dim white light or dim 500 nm light, the axial distributions observed in the rods still conformed to the "bleaching only" model, even after exposures lasting up to 2 hours. But after 4 hours, a redistribution occurred. The rhodopsin content became highest in the region where the "bleaching only" model predicted that it should be the lowest. / When the monochromatic illuminant was attenuated tenfold, the gradient reversal was not observed. The axial patterns of rhodopsin remaining could be described by the "bleaching only" model after light exposure periods lasting up to 4 hours. / The distributions of rhodopsin remaining provide some understanding of the patterns of excitation and adaptation in rod photoreceptors. Some of the possible consequences to vision are discussed. / Source: Dissertation Abstracts International, Volume: 48-07, Section: B, page: 1872. / Thesis (Ph.D.)--The Florida State University, 1987.

Human fibroblasts possess five distinguishable systems for amino acid transport. Initial rates for three of these normalized against cell protein decline with in vitro age. The decline most noticably affects the L system, whose rate for L-phenylalanine transport at 10 uM declines by 44% between the 27th and 39th population doubling levels. Accumulation of L-phenylalanine at 10 uM is similarly affected by age. / In spite of L system transport reduction, pool levels of L system amino acids do not decline markedly with age. The present study found the total pool for five L system amino acids (val, ileu, leu, tyr, phe) as 29 nmol mg('-1) in IMR-90-20 and 27 nmol mg('-1) in IMR-90-35. A previous study from another laboratory has reported small (15%) reductions of L system amino acids as a fraction of the total pool in high passage cells. The absence of an L system pool decline proportional to the L system transport decline is probably attributable to the high concentrations of amino acids in growth medium in comparison to the substrate concentration used in transport assays (800 uM vs. 10 uM for L-phenylalanine). / Growth of fibroblasts is relatively insensitive to pool alterations irrespective of age. Fivefold dilution of the amino acid complement of culture medium (DME) reduced L system amino acid pools about 40% in both young and old cells without significantly affecting growth. The lack of a strong age effect on amino acid pools and the additional insensitivity of older cells to reduction of the amino acid concentration of culture medium casts doubt on possible interpretation of the transport decline as a causal factor limiting growth. / Source: Dissertation Abstracts International, Volume: 46-04, Section: B, page: 1030. / Thesis (Ph.D.)--The Florida State University, 1985.

Tests of life history theory are usually made by comparing clusters of traits among populations that are known or suspected to differ in some critical environmental factor. Many problems exist in these types of comparisons including obtaining accurate demographic information and identifying the unit of evolution in the field. Another area where there is a striking lack of information is on the genetic structure of life history traits. Little work has been done to separate phenotypic plasticity from genetic divergence, which would provide a basis on which selection can act. Selection is also assumed to work on each trait independently, although the occurrence of traits in specific groups might be based on complex genetic and environmental correlations. / Two populations of a local species of freshwater pulmonate gastropod, Physella hendersoni ariomus (Clench) were selected for investigation of the environmental and genetic contributions to observed life history characteristics. These populations were found to differ in size at first reproduction, fecundity, population density and size class distribution. Physico-chemical characteristics of the two habitats also varied in the levels of dissolved oxygen, dissolved calcium carbonate, pH and constancy of water temperature. / Further analyses indicated that both temperature and population source have a significant effect on the expression of life history traits for these populations. Through the use of inbred lines, the phenotypic, genetic and environmental contributions to life history traits were further delineated. Heritabilities of life history traits for these populations were generally low, and a moderate amount of non-additive genetic variance was found for estimates of growth and fecundity. Genetic correlations between size at first reproduction and later fecundity shifted in both magnitude and direction depending upon the environment in which they were measured. Phenotypic and environmental correlations between traits were generally positive and were also strongly influenced by the immediate environment. / The genetic structure of life history traits in these populations is consistent with that predicted for traits that have been subjected to strong directional selection, implicit in life history theory. The genetic divergence between these populations can therefore be attributed, at least in part, to divergent selection pressures. / Source: Dissertation Abstracts International, Volume: 48-08, Section: B, page: 2181. / Thesis (Ph.D.)--The Florida State University, 1987.

This study describes the isolation of the mt('- )mating type substance (MTS) by means of zwitterionic detergents and ultrasonication. The component is an extremely high molecular weight glycoprotein of more than 3 million daltons and could be characteized in essential features of its functional structure. In contrast to the multivalent mt('-) isoagglutinin, from which it is isolated, the MTS is incapable of causing homotypic agglutination between mt('+) gametes. The "univalent" glycoprotein has been crosslinked with poly-L-lysine and carbodiimide to reestablish a multivalent principle capable of agglutinating mt('+) gametes. The synthesized principle possesses the same enzyme sensitivities as the mt('-) gametes, being inactivated by the (alpha)-exogalactosidase and (alpha)-exo-N-acetyl-galactosaminidase. The real ligand within the glycoprotein is therefore of carbohydrate nature with terminal galactose and N-acetylgalactosamine residues in (alpha)-linkage. Gamete contact thus depends decisively on carbohydrate binding. The insensitivity of the attainment of the mt('-) contact capacity to Tunicamycin and Bacitracin, the sensitivity of the established contact capacity to alkaline borohydride reduction and to (alpha)-D-N-acetylgalactosaminyl-oligosaccharidase and the insensitivity to Endoglycosidase H indicate that, within the MTS, the ligand involved in recognition and adhesion must be O-glycosidically linked to the polypeptide chain. / In spite of the essential role of these terminal sugars the mt('-) MTS could not be masked by lectins nor did the mt('-) gametes selectively adhere to lectin-coated agarose beads. When checked with both gamete types, the synthesized multivalent principle exhibits the same sex and species specificity as the mt('-) gametes. These data on the mt('-) MTS reveal a fundamental pattern of the gametic biopolarity and its biosynthesis, whereas the contact capacity in the complementary mt('+) sex is inherent in an N-linked carbohydrate structure and synthesized by the lipid-linked pathway, the mt('-) capacity seems to reside in an O-glycosidically linked ligand. A second gametic bipolarity appears to reside in the components involved in the initiation of gamete fusion. The pairing capacity of the mt('-) gametes is inhibited by the effects of Bacitracin, while the contact capacity with respect to the mating type reaction is not. / Source: Dissertation Abstracts International, Volume: 44-01, Section: B, page: 0026. / Thesis (Ph.D.)--The Florida State University, 1982.

Source: Dissertation Abstracts International, Volume: 31-09, Section: B, page: 5173. / Thesis (Ph.D.)--The Florida State University, 1970.

Source: Dissertation Abstracts International, Volume: 32-01, Section: B, page: 0090. / Thesis (Ph.D.)--The Florida State University, 1970.

Source: Dissertation Abstracts International, Volume: 32-01, Section: B, page: 0092. / Thesis (Ph.D.)--The Florida State University, 1970.

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