bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gene transfer in swine embryos by injection of cells infected with retrovirus vectors
Authors: Petters Robert M. , Shuman Ruth M. , Johnson Bryan H. , Mettus Richard V. 
Published: June 2005

AbstractKey components for gene transfer to swine embryos using an avian retrovirus are described. A replication‐defective reticuloendotheliosis (REV) viral vector can infect and be expressed in pig embryo fibroblasts (PEF). Infection with a replication‐competent vector (REV‐A) indicates a presumptive block to viral replication in PEF. Swine embryos obtained at the morula stage can be cultured in vitro to the blastocyst stage, injected with retrovirus helper cells or quail embryo fibroblasts producing REV, and transferred to recipient swine with survival to at least 6 wk of gestation.
Isolation of viable mouse primordial germ cells by antibody‐directed flow sorting
Authors: McCarrey John R. , Hsu Katharine C. , Eddy E. M. , Klevecz Robert R. , Bolen James L. 
Published: June 2005

AbstractThe germ line represents a cell type of unique interest in mammals because it retains complete genotypic totipotency while undergoing significant phenotypic differentiation. Analysis of the mechanism that underlies the maintenance of this totipotency requires the ability to isolate and study all stages of the germ cell lineage. The primordial germ cells (PGC) are the earliest identifiable germ cells in the embryo. It has not previously been possible to isolate PGC in sufficient numbers and purity to facilitate biochemical and/or molecular analysis. We report here that the use of a monoclonal antibody in combination with flow cytometry does permit the isolation of reasonably large and pure yields of viable mouse PGC.
The relationship between plasma proteins and intracellular free amino acids during osmotic regulation in Carcinus maenas
Authors: Zatta Paolo 
Published: June 2005

AbstractThe osmoregulatory behavior of the Adriatic population of the shore crab Carcinus maenas is similar to that of more northern populations. Hyperosmotic regulation of the hemolymph is initiated below about 95–85% seawater (973–871 m Osm/kg) and slight hypo‐osmotic regulation appears to occur above approximately 110% seawater (1,127 m Osm/kg). Extracellular volume is actively regulated, and changes in levels of amino acids imply effective regulation of intracellular volume. Serum protein levels increase immediately after transfer of the crabs from high to low salinity, although the changes are much smaller than those reported by other investigators. Levels of free amino acids in serum decrease after transfer from high to low salinity and labeled leucine is incorporated into hemocyanin at a greater rate after such a transfer than in the absence of a change in salinity. However, the rate of incorporation of leucine is also greater at low than at high ionic strength in vitro, in cell‐free preparations. This result suggests that the experiment does not demonstrate storage of intracellular free amino acids by the extracellular oxygen carrier, but rather reflects “passive” binding to hydrophobic sites on the hemocyanin molecule.
Full‐term development of mouse blastomere nuclei transplanted into enucleated two‐cell embryos
Authors: Tsunoda Y. , Yasui T. , Shioda Y. , Nakamura K. , Uchida T. , Sugie T. 
Published: June 2005

AbstractThe nuclei from four‐ and eight‐cell mouse embryos were transplanted into enucleated two‐cell embryos. It was found that such embryos not only developed to the blastocyst stage in vitro (72% and 35%), but also developed to full term (22% and 8%) after transfer to recipient mice. However, development of embryos which contained nuclei from the inner cell mass was not observed. Since the development of enucleated zygotes which contain advanced nuclei is limited (the present study; McGrath and Solter: Science, 226: 1317–1319, '84; Robl, Gilligan, Critser, and First: Biol Reprod., 34:733–739, '86), it appears that cytoplasmic factors are important for the development of nuclei from advanced cells.
Appearance and developmental kinetics of a unique cell type in Dictyostelium discoideum: Is it the gamete phase of sexual development?
Authors: O'Day Danton H. , McConachie David R. , Rivera Jiji 
Published: June 2005

AbstractA unique cell type appears during sexual development in Dictyostelium discoideum. These tiny ameboid cells migrate actively making both short‐lived and stable contacts with other cells. When fixed and stained with Hoechst 33258, each of these small amebae is seen to possess a condensed fluorescent nucleus. The cell type demonstrates a transient appearance in mated cultures appearing prior to 8 h and increasing to a peak of about 16% of the cell population by 10 h before decreasing in number. The decrease is correlated with the formation of pre‐zygotic, binucleate cells. In single strain cultures, the small cells are present at 8 h and rise to a plateau by 10–12 h but do not decrease in number, and pre‐zygotic binucleate cells do not form. The events of cell fusion were observed directly using time‐lapse video microscopy. The unique structure, developmental kinetics, and behavior of the cell type suggest that it may be the gametic phase of D. discoideum.
Lingual responces to chemical fractions of urodaeal glandular pheromone to the skink Eumeces laticeps
Authors: Cooper William E. , Grastka William R. 
Published: June 2005

AbstractChemical fractions of the female sex pheromone of Eumeces laticeps were extracted from whole urodaeal glands and bioassayed for their ability to induce elevated tongue‐flicking rates in conspecific males. Females were treated with estradiol to maximize pheromone production before removal of the urodaeal glands; males were implanted with testosterone in Silastic capsules to maximize responsiveness to the pheromone. Males emitted signifi‐cantly higher tongue‐flick rates in response to the neutral lipid fraction of urodaeal homogenate than to acidic lipids, basic lipids, or a peanut oil control. No significant differences in ability to induce tongue‐flick rates were observed between the carbohydrate fraction of urodaeal homogenate, the protein fraction, and deionized water. Thus, pheromonal activity appears to reside in the neutral lipid fraction, but in none of the others tested.
Reptilian Skeletal Muscle: Contractile properties of identified, single fast‐twitch and slow fibers from the lizard Dipsosaurus dorsalis
Authors: Gleeson Todd T. , Johnston Ian A. 
Published: June 2005

AbstractContractile properties and innervation patterns were determined in identified single fibers from the iliofibularis muscle of the desert iguana, Dipsosaurus dorsalis. Single fibers from both the red and white regions of the iliofibularis muscle were dissected along their length under oil and a portion was mounted on transducers for determination of maximum isometric tension (Po) and unloaded shortening velocity (Vmax) using the slack test method. Fibers were chemically skinned and activated by high Ca++. The remaining portion of the muscle fiber was mounted on a glass slide and histochemically treated to demonstrate myosin ATPase activity. Fibers studied functionally could therefore be classified as fast or slow according to their myosin ATPase activity, and they could also be classified metabolically according to the region of the muscle from which they were dissected. Fast‐twitch glycolytic (FG) fibers from the white region and fast‐twitch oxidative, glycolytic (FOG) and slow fibers from the red region had shortening velocities at 25°C of 7.5, 4.4, and 1.5 l·s−1, respectively. Po did not differ in the three fiber types, averaging 279 kN·m−2. In a second experiment, 10 pm sections were examined every 30 pm through the proximal‐most 7.5 mm of the iliofibularis muscle for motor endplates. Sections were stained to demonstrate regions of acetylcholin‐esterase activity. Fibers with visible endplates were classified in serial sections by histochemical treatment for myosin ATPase and succinic dehydrogenase. All slow fibers examined (n = 22) exhibited multiple endplates, averaging one every 725 pm. All FOG and FG fibers (N = 10) had at most one endplate in the same region. The data suggest that fibers histochemically typed ‘slow’ in Dipsosaurus are a single population of slow‐contracting fibers, all of which are multiply innervated. The available data on these fibers are evaluated and an argument is made that this type of fiber in lizards is best described as ‘slow’ rather than ‘tonic,’ for although they are multiply innervated and capable of graded contractions, they have other characters that are common to fibers capable of a twitch.
Metamorphosis of the American eel, Anguilla rostrata LeSeur: III. Contractile characteristics of skeletal muscle
Authors: Egginton Stuart 
Published: June 2005

AbstractPrevious work has suggested a common migratory strategy among fishes may involve changes in recruitment pattern of skeletal muscle types, allowing fast muscle to function continuously. In this study no evidence was found for changes in adenine nucleotide metabolism, thought to be important in fatigued muscle, with metamorphosis from the nonmigratory yellow to migratory silver eel in either slow or fast muscle tissue. Myofibrillar ATPase activity was found to be lower than reported values for other teleosts, around 0.075 and 0.17 μM inorganic phosphate mg−1 min−1 for slow and fast muscle, respectively. No change was found in the Ca+ +‐kinetics of the enzyme within either muscle type. Likewise, no change in the contractile performance of fast muscle was evident, arguing against changes in activity pattern. In contrast to mammalian endurance exercise training where major changes in aerobic capacity occur in fast muscle, migratory pre‐adaptation in eel appears to be restricted to changes in slow muscle performance. A displacement of the slow muscle force‐velocity curve to the right upon metamorphosis results in 30% increase in the tension developed at maximal power output from 2.4 to 3.2 N cm−2. The difference in migratory potential between yellow and silver eels was shown previously to involve an increased aerobic capacity. The change in contractile characteristics may further improve endurance by permitting a portion of the tissue to periodically replenish endogenous energy stores.
Hormonal control of gluconeogenesis in rainbow trout hepatocytes: Regulatory role of pyruvate kinase
Authors: Petersen T. D. P. , Hochachka P. W. , Suarez R. K. 
Published: June 2005

AbstractGluconeogenesis from lactate in hepatocytes from rainbow trout is activated by glucagon and inhibited by insulin in a dose‐dependent fashion. The maximal responses to both hormones occur within their probable physiological concentration ranges. Gluconeogenic activation by glucagon is accompanied by a profound inhibition of pyruvate kinase activity. This is reflected in increases in both the S0.5 and nH for phosphoenolpyruvate and increased sensitivity to inhibition by MgATP compared to the enzyme isolated from cells not treated with hormone (control). Gluconeogenic inhibition by insulin is accompanied by activation of pyruvate kinase activity. This is observed as decreases in both the S0.5 and nH for phosphoenolpyruvate and a decreased sensitivity to inhibition by MgATP compared to enzyme isolated from control cells. These results indicate that insulin and glucagon are involved in the regulation of hepatic gluconeogenesis in trout and that their effects are mediated, at least partly, through the control of pyruvate kinase activity.
Glutamine synthetase in liver and brain tissues of the holocephalan, Hydrolagus colliei
Authors: Ritter Nadine M. , Smith Darwin D. , Campbell James W. 
Published: June 2005

AbstractGlutamine synthetase was shown to be mitochondrial in liver tissue and cytosolic in brain tissue of the holocephalan Hydrolagus colliei. The liver mitochondrial form has an Mr approximately 1,500 larger than the brain cytosolic form, so the two represent compartmental isozymes. Similar isozymes have been shown to be present in elasmobranchs, and their occurrence in holocephalans suggests the two groups share a common ancestry.
Behavior of “Accessory” somatic and sperm nuclei introduced into physiologically polyspermic newt eggs
Authors: Yamasaki Hisashi , Iwao Yasuhiro 
Published: June 2005

AbstractIn an attempt to understand the mechanism of the accessory sperm nuclei degeneration in the physiologically polyspermic eggs of the newt Cynops pyrrhogaster, nuclei from homologous somatic cells or from sperm of an anuran, Bufo japonicus, were injected into fertilized eggs of Cynops. Homologous blastula nucleus injected into eggs 1–2 hours after fertilization, behaved in synchrony with the zygote nucleus, although all the fertilized Cynops accessory sperm nuclei underwent degeneration. When 1–24 Bufo sperm treated with 0.025% Triton X‐100 were injected into individual Cynops eggs 1–1.5 or 3.5–4 hours after fertilization, none degenerated; they either joined the mitotic plate or the zygote nucleus, or they formed additional mitotic apparatus. However, when the Cynops eggs were inseminated with a higher concentration of sperm from Hynobius nobulosus or H. retardatus, several sperm penetrated each egg, followed by the formation of a zygote nucleus or multipolar spindles. A high frequency of the eggs that were injected with either blastula‐, Bufo sperm‐ or Hynobius sperm‐nuclei underwent an irregular multipolar cleavage. These results suggest that the accessory sperm‐suppressing activity in the cytoplasm of physiologically polyspermic Cynops egg affects only homologous sperm nuclei in a specific way.
Characterization of human sperm plasma membrane: Glycolipids and polypeptides
Authors: Mack S. R. , Zaneveld L. J. D. , Peterson R. N. , Hunt W. , Russell L. D. 
Published: June 2005

AbstractThe plasma membranes from ejaculated human spermatozoa were removed by nitrogen cavitation (600 PSI for 10 min) and isolated by centrifugation followed by a discontinuous sucrose density gradient centrifugation. Glycolipid analysis of the plasma membrane revealed a three‐fold enrichment in gangliosides: GM3 and GD1a/GD1b and neutral glycolipids: globoside and sulfatide as compared to that of whole human sperm. Two dimensional electrophoresis of human sperm plasma membranes revealed about 75 polypeptides. Several of these polypeptides were similar in migration and in display of shape and color to that found in boar sperm plasma membranes.
Development and keratinization of the epidermis in the common lizard, Anolis carolinensis
Authors: Carver Wayne E. , Sawyer Roger H. 
Published: June 2005

AbstractEpithelial‐mesenchymal interactions play important roles in the development of the vertebrate integument with its diverse appendages. As a result of these interactions, specific morphogenetic events occur which result in the formation of distinct epidermal appendages. Following the early morphogenetic events involving cell proliferation and movement, other developmental events such as stratification, histotypic differentiation, and terminal cytodifferentiation occur in the epidermis. Using the common lizard Anolis carolinensis, we are seeking to obtain a better understanding of the relationship between the various developmental events and the expression of α and β keratins, with the aim of eventually understanding the mechanisms by which tissue‐specific keratinization patterns are established in the integument. As a first step, we have used immunoblot analyses and indirect immunofluorescence procedures with antisera specific for either α or β keratins to determine the temporal and spatial appearance of these keratins at specific developmental stages. We have found that: 1) There are relatively low molecular weight α keratin polypeptides present in the epidermis early in development as morphogenesis is taking place. 2) After morphogenesis occurs and histogenesis is well under way, the α keratins which characterize the adult epidermis appear. 3) Only α keratins are found in the basal cells of all regions of the epidermis. 4) β keratins are found only in the suprabasal layers of well‐developed scales and show region‐specific distribution in overlapping scales.
Tyrosinase activity and the expression of the agouti gene in the mouse
Authors: Movaghar M. , Hunt D. M. 
Published: June 2005

AbstractTyrosinase activity at the time of phaeomelanin synthesis in neonatal mice is lower in agouti than in black skin and hair bulb tissue, and this depressed activity is associated with a reduction in the electrophoretically distinct de novo form of the enzyme. Direct chemical measurements of sulphydryl compounds show elevated levels in agouti hair bulb tissue at this stage of development. The addition of exogenous copper to hair bulb extracts raises the activity of tyrosinase in agouti to approximately the black level but has no effect on black itself. These results are discussed in relation to the role of sulphydryl compounds and copper availability in regulating tyrosinase activity and turnover.
Ultrastructural localization of lysosomal enzymes in the egg cortex of Brachydanio
Authors: Hart Nathan H. , Wolenski J. S. , Donovan M. J. 
Published: June 2005

AbstractThe localization of acid phosphatase (E.C. 3.1.3.2), inorganic trimetaphosphatase (E.C. 3.6.1.2), and aryl sulfatase (E.C. 3.1.6.1) in the cortex of unactivated and activated eggs of Brachydanio was examined by ultrastructural cytochemistry. Using a lead capture method, activity for all three acid hydrolases was demonstrated in organelles of the cortex before and after egg activation. Acid phosphatase (AcPase) reaction product was consistently present in primary lysosomes, secondary lysosomes, multivesicular bodies, and yolk bodies. AcPase activity was absent from mitochondria, profiles of the endoplasmic reticulum, coated pits of exocytosed cortical granules, and coated vesicles. Although most cortical granules of the mature, unactivated egg were unreactive for this enzyme, a few showed AcPase reaction product. It is not clear whether the AcPase‐positive granules might be an immature form of cortical granules or a subpopulation of these organelles with lysosomal properties. Most cisternae of the Golgi apparatus did not stain for AcPase; however, reaction product was occasionally localized in a single cisterna as well as several small vesicles at the inner face of the Golgi. The intensity of the reaction product and the pattern of distribution of trimetaphosphatase (TmPase) activity was very similar to that of AcPase. However, TmPase was never observed in cortical granules. Cortices of unactivated and activated eggs showed less overall aryl sulfatase (ArSase) activity when compared with AcPase and TmPase. The presence of ArSase reaction product in lysosomes and multivesicular bodies confirmed the acid hydrolytic nature of these organelles. AcPase and TmPase, and to a lesser extent ArSase, are adequate markers of a cortical lysosomal system in the danio egg. Our results are consistent with the view that membrane, retrieved from the egg surface during the cortical reaction and shuttled into organelles with lysosomal properties (i.e., secondary lysosomes and multivesicular bodies), undergoes degradation. However, our study does not exclude other possibilities for handling internalized membrane, including storage and recycling to the plasma membrane.
Separation of vanadocytes: Determination and characterization of vanadium ion in the separated blood cells of the ascidian, Ascidia ahodori
Authors: Michibata Hitoshi , Hirata Junko , Uesaka Michiko , Numakunai Takaharu , Sakurai Hiromu 
Published: June 2005

AbstractAscidian blood cells contain a level of vanadium ion much higher than that in seawater. Blood cells are generally classified into six to nine types based on their morphology. On the basis of a Ficoll gradient for cell fractionation, neutron activation analysis of vanadium ion, and ESR spectra of oxovanadium ion in blood cells, the signet ring cells are the most likely “vanadocytes” in Ascidia ahodori. The vanadyl ion (VO2+), detected in high levels in these cells, binds with some low molecular weight substances through their oxygen donors.
MSORTV imaging of electrotonic conduction in a syncitium: Optical recording of polarization spread in a simple salivary gland
Authors: Senseman D. M. , Horwitz I. S. , Salzberg B. M. 
Published: June 2005

AbstractThe spread of hyperpolarizing current injected into the salivary gland of the snail Helisoma trivolvis was studied with the technique of multiple site optical recording of transmembrane voltage (MSORTV). Using MSORTV it was possible to monitor simultaneously the spread of current passed by an intracellular microelectrode in up to 124 separate gland regions. Our results demonstrate the feasibility of combining conventional intracellular injection techniques with MSORTV to visualize 2‐dimensional current spread in an electrical syncitium.
Comparative studies of Bufo and Xenopus vitelline coat molecular transformations induced by homologous and heterologous oviducal pars recta proteases
Authors: Takamune Kazufumi , Lindsay Leann , Hedrick Jerry L. , Katagiri Chiaki 
Published: June 2005

AbstractThe vitelline coats (VCs) of Bufo japonicus and Xenopus laevis undergo coelomic egg (CEVC)‐ to uterine egg (UEVC)‐type conversions, after passage through the pars recta (PR) portion of oviduct or treatment of eggs with secretory granules from PR (PRGs), as determined by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) analyses of glycoproteins. These conversions include for Bufo the loss of 40K–52K components from the CEVC, concomitant with increasing stainability of a 39K component and the appearance of a 36K component in the UEVC. For Xenopus, a 43K glycoprotein in the CEVC is transformed to a 41K glycoprotein in the UEVC. When coelomic eggs of both Bufo and Xenopus were treated with PRGs from the heterologous species, the macromolecular components of the VCs were processed in exactly the same way as with homologous PRGs. The PRGs from both species showed strikingly similar hydrolytic activities against Boc‐Val‐Leu‐Lys‐MCA and several peptidyl‐Arg‐MCAs. Bufo coelomic eggs treated with Xenopus PRGs were not fertilizable by Bufo sperm, whereas treatment with Bufo PRGs rendered the eggs fertilizable. We conclude that the oviductal enzymes and VC substrates in these species are evolutionarily conserved and that macromolecular alterations of VC glycoproteins as detected by SDS‐PAGE are necessary, but not sufficient, for making coelomic eggs fertilizable.
Formation of cartilage in organ‐cultured leg buds of chick embryo
Authors: Suzuki Hiroaki R. , Ide Hiroyuki 
Published: June 2005

AbstractWhen the leg buds from chick embryos at stages 17–23 were cultured as organ cultures in F12 medium, which contained chick serum and an extract of chick embryos, leg cartilage structures developed that included pelvic girdle, femur, tibiofibula, and tarsometatarsus. The proportion of explants with definite distal elements increased when the leg buds from later embryos were used. Supplementation with chick serum was essential. These results suggest that the pattern of formation of limbs in chick embryos can be studied in organ culture.
A Possible contractile role for myoepithelial cells in the trachea of the Australian snake‐necked tortoise, Chelodina longicollis
Authors: Smith R. V. , Hards D. K. , Satchell D. G. 
Published: June 2005

AbstractThe trachea of the Australian snake‐necked tortoise, Chelodina longicollis was studied using histological, immunohistochemical, ultrastructural and organ bath pharmacological techniques. The trachea has complete cartilage rings with dense connective tissue between them. No smooth muscle cells were found. Electrical stimulation of tracheal tube and strip preparations elicited marked contractile responses. Myoepithelial cells containing smooth muscle myosin and bundles of thin filaments were demonstrated between the basement membrane and the mucous and ciliated cells of the epithelium lining the tracheal lumen. These myoepithelial cells could account for the contractions observed and may be involved in the expulsion of mucus.