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Articles 1 - 17 of 17
Full-Text Articles in Life Sciences
The Gallbladder Of Uranoscopus Scaber L. (Teleost Perciform Fish) Is Lined By Specialized Cholecystocytes, Donald Ott, J Gilloteaux, Carla Oldham-Ott
The Gallbladder Of Uranoscopus Scaber L. (Teleost Perciform Fish) Is Lined By Specialized Cholecystocytes, Donald Ott, J Gilloteaux, Carla Oldham-Ott
Donald W. Ott
The gallbladder of Uranoscopus exhibits a mucosal surface layer of simple columnar epithelium composed of specialized cholecystocytes. The apices show storage and mucous secretions, typical microvilli, and very apical projections extending deep into the luminal contents. Many organelles and heterogeneous vesicles of diverse size fill the cytoplasm, including neutral mucins, mitochondria, peroxisomes, lysosomal bodies, and lipid-rich deposits with cholesterol inclusions. The fibromuscular layer shows little blood supply and contains scattered lymph-like walls with minute cholesterol inclusions. The remaining muscular, subserosal, and serosal or adventitial layers of this species do not show any histologic differences to those of other vertebrates. It …
Androdioecy And Hermaphroditism In Five Species Of Clam Shrimp (Crustacea: Branchiopoda: Spinicaudata) From India And Thailand, Donald Ott, Stephen Weeks, Robert Duff, Justin Brantner
Androdioecy And Hermaphroditism In Five Species Of Clam Shrimp (Crustacea: Branchiopoda: Spinicaudata) From India And Thailand, Donald Ott, Stephen Weeks, Robert Duff, Justin Brantner
Donald W. Ott
Crustaceans in the order Spinicaudata display a broad range of reproductive strategies, ranging from pure hermaphroditism to pure dioecy (separate males and females), and intermediate combinations. One particularly interesting genus of these “clam shrimps” is Eulimnadia. Based on offspring sex ratios, it has been suggested that all members of the genus are androdioecious: populations consist of mixtures of males and hermaphrodites. However, only two of the ~40 species in this genus have been examined histologically to confirm the presence of ovotestes in the purported hermaphrodites of this group. Here, we report both sex ratio and histological evidence showing that populations …
Developmental Cytology Of The Genus Vaucheria Iv. Spermatogenesis, Donald Ott, R Brown
Developmental Cytology Of The Genus Vaucheria Iv. Spermatogenesis, Donald Ott, R Brown
Donald W. Ott
Spermatogenesis among several species of Vaucheria has been examined in sections prepared for light and electron microscopy. Early developmental stages of zoosporogenesis and spermatogenesis are identical; however, cytoplasmic cleavage progresses to completion in the antheridium, while incipient cleavage is rudimentary in the zoosporangium. During morphogenesis of the antheridium, nuclear cyclosis is inhibited and flagella develop from nucleusassociated basal bodies. The flagella project into internal membrane reservoirs (termed flagellar pools) which, unlike their counterparts in zoosporogenesis, fail to migrate to the surface of the antheridium, while chloroplasts are excluded from uninucleate protoplasmic segments by completion of cleavage furrow development.
Microscopic Observation Of Filter Cake Formation, Donald Ott, G Chase, J Steffen
Microscopic Observation Of Filter Cake Formation, Donald Ott, G Chase, J Steffen
Donald W. Ott
Particle collisions and filter cake collapse are observed through a microscope during the formation of filter cakes. Cake filtration is widely applied throughout industry for fluid-particle separations. Models and theories have been developed to describe and predict filter cake performance, but there is little literature on direct observation of particle packing and cake formation. A filter assembly the size of a microscope slide is placed on the microscope such that the slurry flow and cake formation is across the field of view. The cake formation is recorded on video tape. Photographs of the video image show particles in the slurry …
Vegetative Reduction In Epiphytic Bromeliaceae And Orchidaceae: Its Origin And Significance, Donald Ott, D Benzing
Vegetative Reduction In Epiphytic Bromeliaceae And Orchidaceae: Its Origin And Significance, Donald Ott, D Benzing
Donald W. Ott
Assays of the roots and leaves of nine leafy and three "shootless" orchids indicated that the roots of the latter, as well as those of leafy Kingidium taeniale, engaged in CAM metabolism and possessed relatively high chlorophyll contents. All leaves were similar on both counts. Except for those of K. taeniale, the roots of the leafy orchids assayed were pale green and incapable of exhibiting a net carbon gain during day or night runs. A labeling experiment with leafy Encyclia tampensis indicated that its green roots did fix small quantities of carbon dioxide and that some of the product was …
Bed And Breakfast: The Parasitic Life Of Proales Werneckii (Ploimida: Proalidae) Within The Alga Vaucheria (Xanthophyceae: Vaucheriales), Donald Ott, Robert Wallace, Sheri Stiles, Carla Oldham-Ott
Bed And Breakfast: The Parasitic Life Of Proales Werneckii (Ploimida: Proalidae) Within The Alga Vaucheria (Xanthophyceae: Vaucheriales), Donald Ott, Robert Wallace, Sheri Stiles, Carla Oldham-Ott
Donald W. Ott
The unusual parasitic association between Proales werneckii (Ehrenberg, 1834) (Ploimida: Proalidae) and the psychrophilic, coenocytic, filamentous alga, Vaucheria De Candolle, 1801 (Xanthophyceae: Vaucheriales), is documented using light and electron microscopy. A young female rotifer colonizes a Vaucheria filament (ca. 80 m 10 cm) by gaining entrance to the cell at a growing region where the wall has not yet matured. After achieving access to the cell, it disrupts development of either a gametophore or an apical tip by inducing cell hypertrophy and formation of an excrescent gall (ca. 80–120 140–1500 m). Remaining within the vacuole of the gall for the …
The Gallbladder Of The Electric Ray Torpedo Marmorata Risso Deplays Excrescent Cholecystocytes With Merocrine And Apocrine-Like Secretions, Donald Ott, J Gilloteaux, Carla Oldham-Ott
The Gallbladder Of The Electric Ray Torpedo Marmorata Risso Deplays Excrescent Cholecystocytes With Merocrine And Apocrine-Like Secretions, Donald Ott, J Gilloteaux, Carla Oldham-Ott
Donald W. Ott
The gallbladder of Torpedo marmorata exhibits a mucosal surface layer of simple columnar epithelium with very tall cholecystocytes. The apical domain of each cell has few microvilli, but many mucous vesicles that are secreted by exocytosis at the cell apices. The apical regions may also elongate and undergo self-excision while shedding mucus and cell debris into the gallbladder lumen in a manner similar to that described in mammals as a result of sex steroid treatment to induce gallstones and to that found in the cholecystitis associated with cholelithiasis. Numerous small mitochondria, spherical to elongated, are distributed throughout the cells, while …
Developmental Cytology Of The Genus Vaucheria Iii. Emergence, Settlement And Germination Of The Mature Zoospore Of V. Fontinalis (L.) Christensen, Donald Ott, R Brown
Developmental Cytology Of The Genus Vaucheria Iii. Emergence, Settlement And Germination Of The Mature Zoospore Of V. Fontinalis (L.) Christensen, Donald Ott, R Brown
Donald W. Ott
After septum formation and dissolution of the zoosporangial apex wall in Vaucheria fontinalis (L.) Christensen, a multi-flagellated zoospore is released and remains motile for a few hours. Settlement of the zoospore occurs with flagellar retraction, after which a cell wall is formed by peripheral vesicles. Subsequent germination initiates polarity and the development of vegetative filament growth.
Developmental Cytology Of The Genus Vaucheria I. Organisation Of The Vegetative Filament, Donald Ott, R Brown
Developmental Cytology Of The Genus Vaucheria I. Organisation Of The Vegetative Filament, Donald Ott, R Brown
Donald W. Ott
The developmental cytology of the vegetative filament of Vaucheria has been investigated with light and electron microscopes. The vegetative filament consists of three distinct zones: the apical zone, the sub-apical zone and the zone of vacuolation. Organelle distribution and associations in these zones have a primary role in controlling morphogenetic events which influence growth and induce differentiation of sexual and asexual organs. Cell elongation in the polarised vegetative filament occurs by vesicular addition in the apical zone. Two types of active cyclosis are found exclusively in the zone of vacuolation. Nuclear cyclosis involves microtubular bands which associate with persistent centrioles …
Light And Electron Microscopical Observations On Mitosis In Vaucheria Litorea Hofman Ex C. Agardh, Donald Ott, R Brown
Light And Electron Microscopical Observations On Mitosis In Vaucheria Litorea Hofman Ex C. Agardh, Donald Ott, R Brown
Donald W. Ott
The light and electron microscopic cytology of nuclear division in Vaucheria litorea Hofman ex C. Agardh is described. The interphase nucleus contains a prominent nucleolus and is associated with lipid droplets. The nucleus migrates through the coenocytic filament during all phases of division. During early prophase, the centrioles migrate to each pole, and the nucleolus fragments. At metaphase, the intra-nuclear spindles, which consist of continuous and chromosomal microtubules, are enclosed by a fully intact nuclear envelope. The nuclear membrane persists throughout the division. Chromosome separation is accomplished by lengthening of continuous microtubules at anaphase. Considerable elongation of continuous microtubules produces …
Developmental Cytology Of The Genus Vaucheria Ii. Sporogenesis In V. Fontinalis (L.) Christensen, Donald Ott, R Brown
Developmental Cytology Of The Genus Vaucheria Ii. Sporogenesis In V. Fontinalis (L.) Christensen, Donald Ott, R Brown
Donald W. Ott
Vegetative filament apices of Vaucheria which differentiate into zoospores under altered culture conditions have been examined in sections prepared for light and electron microscopy. Soon after the migration and accumulation of cytoplasmic organelles into the filament tip, the centriole pair associated with each nucleus begins to form internal flagella. The flagella and their nuclei converge into many internal flagellar pools which then migrate to the surface of the zoospore and become part of the plasma membrane. These events in the filament apex take place during the septation of the vegetative filament. At the time of zoospore release, all nuclei are …
Roots Of Sobralia Macrantha (Orchidaceae): Structure And Function Of The Velamen-Exodermis Complex, Donald Ott, D Benzing, W Friedman
Roots Of Sobralia Macrantha (Orchidaceae): Structure And Function Of The Velamen-Exodermis Complex, Donald Ott, D Benzing, W Friedman
Donald W. Ott
Roots of Sobrailia macrantha, a largely terrestrial orchid, bear a typical multilayered velamen underlaid by a cortical exodermis. The latter consists of densely cytoplasmic passage cells regularly interspersed among much longer, elongate, vacuolate cells. A structure which may be peculiar to Sobralia, or at least unusually well developed there - the fibrous body - consists of numerous intermeshed and divided wall outgrowths arising from two or three velamen cells positioned directly over the passage cell. This body is well designed to retard root transpiration. Should the fibrellar components be appropriately hygroscopic, it may act as a valve, promoting movements of …
Nonlinear Optical Transmission Of Silk/Green Fluorescent Protein (Gfp) Films, Donald Ott, R Eby, S Putthanarat, Rajesh Naik
Nonlinear Optical Transmission Of Silk/Green Fluorescent Protein (Gfp) Films, Donald Ott, R Eby, S Putthanarat, Rajesh Naik
Donald W. Ott
In this initial work, we demonstrate a technique for preparing thin (10–20 μm) films of silk doped with green fluorescent protein (GFP) by casting/annealing at 20 °C and describe the resulting film characteristics. Notably, the GFP molecules maintain their nonlinear optical properties as evidenced by two-photon fluorescence microscopy and two-photon absorption measurements using near-infrared femtosecond pulses. The fractional transmission of focused near-infrared pulses of 775 nm wavelength, 140 fs pulsewidth was observed to decrease as the incident pulse energy is increased and/or the incident spot size is decreased, indicating that nonlinear absorption is taking place. Visible damage from the pulses …
Effects Of Polyethleneimine On Cyanobacterium Anabaena Flos-Aquae During Cell Flocculation And Flotation, Donald Ott, Sarah Arrington, Margo Zeleznik, Lu-Kwang Ju
Effects Of Polyethleneimine On Cyanobacterium Anabaena Flos-Aquae During Cell Flocculation And Flotation, Donald Ott, Sarah Arrington, Margo Zeleznik, Lu-Kwang Ju
Donald W. Ott
For production of cyanobacterial gas vesicles, polyethyleneimine (PEI) was used as flocculent to enhance the collection of buoyant Anabaena flos-aquae cells by flotation. During the flocculation-flotation process, PEI was found to cause the cells to release blue pigment(s) (presumably phycocyanin) and probably other cytoplasmic materials. The kinetic profile of the pigment release was followed and compared with that of the culture flotation. The effects of PEI on the cyanobacterial cells were also examined using transmission electron microscopy. Unlike the previous reports for the effects of PEI on Gram-negative bacteria, our observations did not reveal significant morphological changes of the PEI-exposed …
Cyst Development In The Conchostracan Shrimp, Eulimnadia Texana(Crustacea: Spinicaudata), Donald Ott, Ronald Salisbury, Stephen Weeks, Vivien Marcus
Cyst Development In The Conchostracan Shrimp, Eulimnadia Texana(Crustacea: Spinicaudata), Donald Ott, Ronald Salisbury, Stephen Weeks, Vivien Marcus
Donald W. Ott
The fertilized egg (or cyst) of branchiopods is a highly resistant stage in the life cycle of these aquatic crustaceans. Previous examinations of these cysts have determined that early embryonic development arrests at a late blastula stage, resulting in a small, crescent-shaped body within the egg shell of these shrimp. Herein, we examine the early development of these embryos by sectioning eggs in the ovotestis, brood chamber, and several time periods after exit from the brood chamber in the clam shrimp Eulimnadia texana Packard. The early sections find no evidence of internal fertilization in the ovotestis. Eggs in the ovotestis …
Incorporation Of Nitric Oxide-Releasing Crosslinked Polyethyleneimine Microspheres Into Vascular Grafts, Donald Ott, Sharon Pulfer, Daniel Smith
Incorporation Of Nitric Oxide-Releasing Crosslinked Polyethyleneimine Microspheres Into Vascular Grafts, Donald Ott, Sharon Pulfer, Daniel Smith
Donald W. Ott
Over the years, many attempts have been made to increase the patency of small- to medium-sized prosthetic vascular grafts. However, none of them has greatly affected long-term rates. Recently, nitric oxide (NO) has been shown to inhibit thrombus formation in such grafts, suggesting that local delivery of NO may help to increase graft patency. This study describes the site-specific delivery of NO by entrapping NO-releasing microspheres in the pores of a vascular graft. NO-releasing polyethyleneimine microspheres (PEIX) were developed using a novel water-in-oil emulsion technique involving chemical crosslinking with a bis-epoxide. The PEIX microspheres were then derivatized with NO forming …
Evidence Of Selfing Hermaphroditism In The Clam Shrimp Cyzicus Gynecia (Branchiopoda Spinicaudata), Donald Ott, Stephen Weeks, Justin Brantner, R Duff
Evidence Of Selfing Hermaphroditism In The Clam Shrimp Cyzicus Gynecia (Branchiopoda Spinicaudata), Donald Ott, Stephen Weeks, Justin Brantner, R Duff
Donald W. Ott
No abstract provided.