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Potato Cultivar Differences Associated With Mealiness, Diane R. McComber, Harry T. Horner, Mark A. Chamberlin, David F. Cox 2016 Iowa State University

Potato Cultivar Differences Associated With Mealiness, Diane R. Mccomber, Harry T. Horner, Mark A. Chamberlin, David F. Cox

Harry Horner

Russet Burbank, Norchip, Pontiac, and LaSoda potato cultivars were examined for the parameters mealy and waxy. Russet Burbank was judged dry, hard and particulate, typifying mealiness. Using phase contrast microscopy and scanning electron microscopy, raw mealy cells were determined to be larger and more irregularly shaped than cells from waxy cultivars. Mealy cooked cells were engorged with gelatinized starch, cell walls were more polarized, and cell shapes were better retained after mashing, when compared to waxy cells. NMR-T2 bound water readings from Russet Burbank and Pontiac samples did not differ from each other. Starch granule sizes and shapes varied by ...


The Genetics, Pathology, And Molecular Biology Of T-Cytoplasm Male Sterility In Maize, Roger P. Wise, Charlotte R. Bronson, Patrick S. Schnable, Harry T. Horner 2016 United States Department of Agriculture

The Genetics, Pathology, And Molecular Biology Of T-Cytoplasm Male Sterility In Maize, Roger P. Wise, Charlotte R. Bronson, Patrick S. Schnable, Harry T. Horner

Harry Horner

This chapter reviews the genetics, pathology, and molecular biology of T-cytoplasm male sterility in maize. The chapter discusses the role of cytoplasmic male sterility systems in facilitating the production of hybrid seeds. The effects of widespread planting of T-cytoplasm maize on the severe 1970 epidemic and effect of a mitochondria1 gene on disease susceptibility and male sterility are discussed. It also discusses the involvement of nuclear cytoplasmic interactions in restoration of cms-T, the perspectives of cms-T researchers, and future directions. In cms-T plants, male sterility is associated with premature breakdown of the mitochondria-rich, tapetal cell layer of the anther; this ...


Formation Of Calcium Oxalate Crystals Associated With Apothecia Of The Discomycete Dasyscypha Capitata, Harry T. Horner, Lois H. Tiffany, Anita M. Cody 2016 Iowa State University

Formation Of Calcium Oxalate Crystals Associated With Apothecia Of The Discomycete Dasyscypha Capitata, Harry T. Horner, Lois H. Tiffany, Anita M. Cody

Harry Horner

Calcium oxalate dihydrate crystals form at or near the tips of sterile hairs on the apothecia of the oak leaf litter discomycete Dasyscypha capitata. Early in their development, the crystals appear to be covered by a wall or membrane, whereas later they appear external. The crystals on each hair form a mass of crystals called a druse. Quite often the smaller crystals near the apex of the tip form a rosette, whereas the more peripheral crystals are much larger and display shapes possibly related to environmental factors. The formation and development of Dasyscypha crystals are compared with recent studies of ...


Early Endosperm, Embryo, And Ovule Development In Glycine Max (L.) Merr., Mark A. Chamberlin, Harry T. Horner, Reid G. Palmer 2016 Iowa State University

Early Endosperm, Embryo, And Ovule Development In Glycine Max (L.) Merr., Mark A. Chamberlin, Harry T. Horner, Reid G. Palmer

Harry Horner

Anatomical and ultrastructural aspects of soybean embryo, endosperm, and ovule development are described for the zygote to late heart-shaped embryo stages (0-35 d postfertilization). Nucellar cells subtending the degenerative synergid break down, allowing for pollen tube passage to this synergid. In 15 of 17 ovules studied, the degenerative synergid occupies a position abfunicular to the zygote. The inner integument differentiates into the endothelium and exterior layers of thick-walled cells at the globular embryo stage. The endothelium has a cuticle on its inner surface that begins to fragment at the onset of endosperm cellularization. Cellularization of the free-nuclear endosperm is initiated ...


Floral Nectary Fine Structure And Development In Glycine Max L. (Fabaceae), Harry T. Horner, Rosaria A. Healy, Teresa Cervantes-Martinez, Reid G. Palmer 2016 Iowa State University

Floral Nectary Fine Structure And Development In Glycine Max L. (Fabaceae), Harry T. Horner, Rosaria A. Healy, Teresa Cervantes-Martinez, Reid G. Palmer

Harry Horner

Floral nectaries of annual cultivated Glycine max develop between the bases of the central gynoecium and lateral stamen ring. Each discoid nectary forms immediately before flower opening and degenerates within 24 h. Three stages of nectary development are identified: preactive, active, and postactive. Preactive and active nectaries are composed of a single-layered epidermis that contains many open stomata, with guard cells having thickened walls, starch-engorged plastids, and other organelles. The major portion of each nectary consists of thin-walled special parenchyma cells, each having dense cytoplasm with a nucleus, Golgi bodies and vesicles, mitochondria, plastids, endoplasmic reticulum, many ribosomes, and one ...


The Preparation Of Carbon-Metal Replicas For The Study Of Carboniferous Coal Ball Fossils: Replication And Cleaning Procedures, Sam W. Rosso, M. Glenn Williams, Harry T. Horner, James Moreland 2016 University of Southern Mississippi

The Preparation Of Carbon-Metal Replicas For The Study Of Carboniferous Coal Ball Fossils: Replication And Cleaning Procedures, Sam W. Rosso, M. Glenn Williams, Harry T. Horner, James Moreland

Harry Horner

In the early stages of a previous study of fossil spores of Botryopteris globosa and B. americana from the Carboniferous (Phillips & Rosso, 1970), considerable difficulty was encountered in replicating and cleaning spore materials and associ- ated debris from the carbon-platinum spore replicas. After numerous attempts to clean these carbon films, the techniques presented in this paper proved ef- ficient and reliable for transmission electron microscope examination of Botry- opteris spores found in calcified coal ball fossils.


Ascorbic Acid: A Precursor Of Oxalate In Crystal Idioblasts Of Yucca Torreyi In Liquid Root Culture, Harry T. Horner, Albert P. Kausch, Bruce L. Wagner 2016 Iowa State University

Ascorbic Acid: A Precursor Of Oxalate In Crystal Idioblasts Of Yucca Torreyi In Liquid Root Culture, Harry T. Horner, Albert P. Kausch, Bruce L. Wagner

Harry Horner

Liquid-cultured primary roots of Yucca torreyi L. (Agavaceae), which are similar to its intact roots, develop uninterrupted files of calcium oxalate crystal idioblasts with raphide bundles in their cortex, beginning just proximal to the terminal meristem. Each single file of idioblasts displays a basipetal ontogenetic sequence. [1-14C]glycolic acid, [1-14C]glyoxylic acid, and L-[1-14C]ascorbic acid, all of which are potential precursors of oxalate, were each added to different flasks that contained a sterile liquid medium and isolated roots and were allowed to interact with the roots for 45 min. After thorough washing, the roots grew for periods that ...


Analysis And Mapping Of Gene Families Encoding Β-1,3-Glucanases Of Soybean, Wei Jin, Harry T. Horner, Reid G. Palmer, Randy C. Shoemaker 2016 Iowa State University

Analysis And Mapping Of Gene Families Encoding Β-1,3-Glucanases Of Soybean, Wei Jin, Harry T. Horner, Reid G. Palmer, Randy C. Shoemaker

Harry Horner

Oligonucleotide primers designed for conserved sequences from coding regions of β-1,3-glucanase genes from different species were used to amplify related sequences from soybean [Glycine max (L.) Merr.]. Sequencing and cross-hybridization of amplification products indicated that at least 12 classes of β-1,3-glucanase genes exist in the soybean. Members of classes mapped to 34 loci on five different linkage groups using an F2 population of 56 individuals. β-1,3-Glucanase genes are clustered onto regions of five linkage groups. Data suggest that more closely related genes are clustered together on one linkage group or on duplicated regions of linkage groups. Northern ...


Mechanisms Of Genic Male Sterility, Harry T. Horner, Reid G. Palmer 2016 Iowa State University

Mechanisms Of Genic Male Sterility, Harry T. Horner, Reid G. Palmer

Harry Horner

For normal sexual reproductive development, coordination must occur between both male and female organ ontogeny. An abnormality at any point in this process may lead to sterility. Classification of sterility can be divided into heritable and nonheritable sterility. Numerous schemes for mechanisms controlled by nuclear genes (genic male sterility) have been devised to identify the timing and location of the inception of sterility. These schemes are divided into structural (gross organ changes) and functional. The latter may be divided into abnormal changes occurring in the male cells or surrounding anther tissues during microsporogenesis. Even though sterility can be produced by ...


Oak-Leaf-Litter Rhizomorphs From Iowa And Texas: Calcium Oxalate Producers, Harry T. Horner, Lois H. Tiffany, George Knaphus 2016 Iowa State University

Oak-Leaf-Litter Rhizomorphs From Iowa And Texas: Calcium Oxalate Producers, Harry T. Horner, Lois H. Tiffany, George Knaphus

Harry Horner

Unidentified basidiomycete rhizomorphs growing on oak-leaf litter {Quercus alba) in Iowa and in Texas {Quercus gravesii) displayed arrays of crystals associated with their hyphae. X-ray diffraction and birefringence analyses identified the crystals as a mix- ture of calcium oxalate-monohydrate and -dihydrate. The Iowa oak-leaf-litter rhizomorph crystals occurred in two forms: young hyphae displayed either small styloid-like crystals oriented in all directions along the hyphae; or large clusters of elongated styloid-like crys? tals surrounding the hyphae, with individual crystals in each cluster displaying pyramidal ends. Crystals as? sociated with the Texas oak-leaf-litter rhizomorphs consistently covered all of the young hyphae and ...


Macropattern Of Styloid And Druse Crystals In Quillaja (Quillajaceae) Bark And Leaves, Nels R. Lersten, Harry T. Horner 2016 Iowa State University

Macropattern Of Styloid And Druse Crystals In Quillaja (Quillajaceae) Bark And Leaves, Nels R. Lersten, Harry T. Horner

Harry Horner

Quillaja has been shuffled among tribes and subfamilies of Rosaceae, segregated from it as a separate family, and, most recently, transferred to the Fabales as a separate family. Many anomalous characters have kept it from being settled anywhere permanently. One character never mentioned by systematists, but long known, is the anomalous (for Rosaceae) occurrence of prominent styloid calcium oxalate crystals, reported from the inner bark of stems. We describe in more detail the macropattern of crystal distribution in stem and leaf, using vibratome sections, sodium hypochlorite clearings of leaves, and polarizing and scanning electron microscopy. Styloids are extremely numerous in ...


Histological Features Of Anthers From Normal And Ms3 Mutant Soybean, H. Nakashima, Harry T. Horner, R. G. Palmer 2016 Hokkaido University

Histological Features Of Anthers From Normal And Ms3 Mutant Soybean, H. Nakashima, Harry T. Horner, R. G. Palmer

Harry Horner

Anthers of male-sterile mutant (ms3) and normal soybean [Glycine max (L.) Merr.] were compared by using a triple-staining procedure for DNA, polysaccharides and proteins, and a single-staining procedure for sporopollenin in conjunction with brightfield and fluorescent microscopy. The purpose of this study was to determine at what stage of anther development histological differences were detectable between male-sterile (ms3) and normal soybean. At the tetrad stage, a prominent greenish-blue material, visible with the triple-staining procedure, filled some of the enlarged tapetal cells of anthers of ms3 plants. This material was also autofluorescent and had an affinity for the ...


Developmental Aspects Of Bacterial Leaf Nodules In Psychotria Bacteriophila Val. (Rubiaceae), Robert E. Whitmoyer, Harry T. Horner 2016 Iowa State University

Developmental Aspects Of Bacterial Leaf Nodules In Psychotria Bacteriophila Val. (Rubiaceae), Robert E. Whitmoyer, Harry T. Horner

Harry Horner

The ontogeny and biological activity of bacterial leaf nodules in Psychotria bacteriophila were studied. The acridine-orange fluorescence method coupled with ribonuclease extractions showed that young and developing nodules were rich in ribonucleic acid (RNA), whereas nodules in older leaves displayed less RNA fluorescence, and nodules in leaves near absciscion did not fluoresce. Fluorescence was attributed to normal and dividing ribosome-rich bacteria. As nodules age, the bacterial population becomes crowded, and de- generating bacteria appear. The latter become a membrane mass which fills the nodule network, replacing the bacteria. The loss of fluorescence is therefore correlated with bacterial cell degeneration. These ...


Development And Structure Of Bacterial Leaf Nodules In Psychotria Bacteriophila Val. (Rubiaceae), Nels R. Lersten, Harry T. Horner 2016 Iowa State University

Development And Structure Of Bacterial Leaf Nodules In Psychotria Bacteriophila Val. (Rubiaceae), Nels R. Lersten, Harry T. Horner

Harry Horner

The development and mature structure of bacterial leaf nodules in Psychotria bacteriophila were studied by using light and electron microscopy. Bacteria in mucilage surrounding the shoot apex pass through certain stomates in leaf primordia into the substomatal chamber. These chambers enlarge and become nodules as the young leaves grow out of the apical region. Surrounding mesophyll cells grow into each nodule and form a cellular reticulum whose interstices are occupied by bacteria. Each intrusive mesophyll cell wall is unusually thick and continually supplemented by vesicles originating from dictyosomes. The gram-negative bacteria are often surrounded by capsules. Nodule bacteria contain several ...


Calcium Oxalate Crystals In Developing Seeds Of Soybean, H. Ilarslan, R. G. Palmer, Harry T. Horner 2016 Ankara University

Calcium Oxalate Crystals In Developing Seeds Of Soybean, H. Ilarslan, R. G. Palmer, Harry T. Horner

Harry Horner

Young developing soybean seeds contain relatively large amounts of calcium oxalate (CaOx) monohydrate crystals. A test for Ca and CaOx indicated that Ca deposits and crystals initially occurred in the funiculus, where a single vascular bundle enters the seed. Crystals formed in the integuments until the embryo enlarged enough to crush the inner portion of the inner integument. Crystals then appeared in the developing cotyledon tissues and embryo axis. All crystals formed in cell vacuoles. Dense bodies and membrane complexes were evident in the funiculus. In the inner integument, cell vacuoles assumed the shape of the future crystals. This presumed ...


Constraints On The Establishment Of Plants Along A Fluctuating Water-Depth Gradient, Eric W. Seabloom, Kirk A. Moloney, Arnold G. van der Valk 2016 Iowa State University

Constraints On The Establishment Of Plants Along A Fluctuating Water-Depth Gradient, Eric W. Seabloom, Kirk A. Moloney, Arnold G. Van Der Valk

Kirk Moloney

We used simulation modeling to investigate the relative importance of current environmental conditions and factors affecting establishment of different plant species on the formation of vegetative zonation patterns. We compared the results from a series of six models that incorporated increasing amounts of information about key factors affecting species' ability to adjust to water-level fluctuations. We assessed model accuracy using aerial photographs taken of a 10-yr field experiment, in which 10 wetlands were flooded to 1 m above normal water level for 2 yr, drawn down for 1 or 2 yr, and reflooded for 5 yr to three different water ...


Finding The Missing Link Between Landscape Structure And Population Dynamics: A Spatially Explicit Perspective, Thorsten Wiegand, Kirk A. Moloney, Javier Naves, Felix Knauer 2016 UFZ-Centre for Environmental Research

Finding The Missing Link Between Landscape Structure And Population Dynamics: A Spatially Explicit Perspective, Thorsten Wiegand, Kirk A. Moloney, Javier Naves, Felix Knauer

Kirk Moloney

We construct and explore a general modeling framework that allows for a systematic investigation of the impact of changes in landscape structure on population dynamics. The essential parts of the framework are a landscape generator with independent control over landscape composition and physiognomy, an individual-based spatially explicit population model that simulates population dynamics within heterogeneous landscapes, and scale-dependent landscape indices that depict the essential aspects of landscape that interact with dispersal and demographic processes. Landscape maps are represented by a grid of 50#50 cells and consist of good-quality, poorquality, or uninhabitable matrix habitat cells. The population model was shaped ...


Population Dynamics, Disturbance, And Pattern Evolution: Identifying The Fundamental Scales Of Organization In A Model Ecosystem, Thorsten Wiegand, Kirk A. Moloney, Suzanne J. Milton 2016 UFZ-Centre for Environmental Research

Population Dynamics, Disturbance, And Pattern Evolution: Identifying The Fundamental Scales Of Organization In A Model Ecosystem, Thorsten Wiegand, Kirk A. Moloney, Suzanne J. Milton

Kirk Moloney

We used auto- and cross-correlation analysis and Ripley’s K-function analysis to analyze spatiotemporal pattern evolution in a spatially explicit simulation model of a semiarid shrubland (Karoo, South Africa) and to determine the impact of small-scale disturbances on system dynamics. Without disturbance, local dynamics were driven by a pattern of cyclic succession, where ‘‘colonizer’’ and ‘‘successor’’ species alternately replaced each other. This results in a strong pattern of negative correlation in the temporal distribution of colonizer and successor species. As disturbance rates were increased, the relationship shifted from being negatively correlated in time to being positively correlated—the dynamics became ...


The Effects Of Disturbance Architecture On Landscape-Level Population Dynamics, Kirk A. Moloney, Simon A. Levin 2016 Iowa State University

The Effects Of Disturbance Architecture On Landscape-Level Population Dynamics, Kirk A. Moloney, Simon A. Levin

Kirk Moloney

Phenomena such as disturbance play a major role in structuring ecological systems by producing a spatiotemporal mosaic of patches at different successional states. The distribution of species within the resulting mosaic depends upon an interaction between species' life history traits and the spatial and temporal structure of the ecological processes controlling species' distributions. We have used a spatially explicit simulation model (Jasper) of a serpentine grassland to examine the importance of some of these relationships, focusing primarily on the role of disturbance. The model Jasper is hierarchical in design and was developed to simulate the population dynamics of three interacting ...


Spreaders, Igniters And Burning Shrubs: Plant Flammability Explains Novel Fire Dynamics In Grass-Invaded Deserts, Andres Fuentes-Ramirez, Joseph W. Veldman, Claus Holzapfel, Kirk A. Moloney 2016 Universidad de La Frontera

Spreaders, Igniters And Burning Shrubs: Plant Flammability Explains Novel Fire Dynamics In Grass-Invaded Deserts, Andres Fuentes-Ramirez, Joseph W. Veldman, Claus Holzapfel, Kirk A. Moloney

Kirk Moloney

Novel fire regimes are an important cause and consequence of global environmental change that involve interactions among biotic, climatic, and human components of ecosystems. Plant flammability is key to these interactions, yet few studies directly measure flammability or consider how multiple species with different flammabilities interact to produce novel fire regimes. Deserts of the southwestern USA are an ideal system for exploring how novel fire regimes can emerge when fire-promoting species invade ecosystems comprised of species that did not evolve with fire. In these deserts, exotic annual grasses provide fuel continuity across landscapes that did not historically burn. These fires ...


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