bluuebunny/crossref_metadata_2025_split huggingface dataset:
Events in the movement of newt epidermal cells across implanted substrates
Authors: Mahan James T. , Donaldson Donald J. 
Published: June 2005

AbstractPieces of coverslip glass, polycarbonate filters, or coverslip plastic, coated with fibrinogen or type I collagen, were implanted under one edge of a fresh skin wound on adult newt hind limbs so that the implant served as wound bed for migrating epidermal cells as they attempted to form a wound epithelium. Migratory events were then analyzed by phase contrast and electron microscopy. Phase‐contrast microscopy revealed two types of lamellipodia on leading edge cells: one which was attached broadly to the cell body and one attached by a long, thin stalk. Stalkless forms were by far the most common type and we believe they provide the motive force for cell movement. Stalked forms often moved at distinct angles to the direction of sheet movement, suggesting that they may be sensory appendages. Phase photographs of the leading edge of migrating sheet 4 hours and 8 hours after implantation showed that all cells that were on the leading edge at 4 hours continued to advance for the next 4 hours, demonstrating clearly that under these circumstances the distalmost cells do not become immobile upon contact with the substrate as others have suggested. TEM revealed that migrating sheets were modified monolayers and that regardless of proximodistal location in the sheet, and even in the intact skin adjoining a wound, each epidermal cell adjacent to the substrate puts forth a lamellipodium which underlaps the cell in front. This and the behavior of sheets as they were teased or pulled from the implant suggest strongly that all basal cells contribute to movement of the sheet by interacting with the substrate. Based on TEM, this interaction may be by either focal or close contacts.
Oxidation of amino acids, Krebs cycle intermediates, fatty acids and ketone bodies by Raja erinacea liver mitochondria
Authors: Moyes Christopher D. , Moon Thomas W. , Ballantyne James S. 
Published: June 2005

AbstractThe oxidation of amino acids, Krebs cycle intermediates, fatty acids and ketone bodies was examined in a well‐coupled mitochondrial preparation from the liver of the little skate, Raja erinacea. Glutamate was the preferred amino acid on the basis of both the respiratory control ratio (RCR; 7.97 ± 0.60 SE) and the state 3 rate (12.50 (± 1.16 SE) nmoles 0 min−1 (mg protein−1). Other amino acids, including sarcosine and β‐alanine, were oxidized at less than one third the rate of glutamate with RCRs less than 4. Oxidation of ornithine and arginine was not detected. Of the Krebs cycle intermediates tested, isocitrate had the best RCR and state 3 rate. Malate enhanced the oxidation of tricarboxylic acids (isocitrate and citrate) and α‐ketoglutarate, probably by stimulation of transport into the mitochondria. Oxaloacetate and succinyl CoA were not oxidized at detectable rates. Pyruvate oxidation was low, even at high concentrations (10 mM). Fatty acids (as carnitine esters) were oxidized at high rates, especially hexanoyl (C‐6), octanoyl (C‐8), decanoyl (C‐10), lauroyl (C‐12), and myristoyl (C‐14) carnitine. Acetoacetate oxidation was not detected, but high rates of oxygen consumption were observed in response to 1 mM β‐hydroxybutyrate. Oxidation of this ketone body was malonate‐sensitive, although 14CO2 production from 3 (14C)‐β‐hydroxybutyrate was minimal, indicating that ketone body carbon was not entering the Krebs cycle. The malonate sensitivity of the oxidation process was due to direct inhibition of β‐hydroxybutyrate dehydrogenase (I50 for malonate = 0.558 (± 0.031 SE) mM). The liver of this skate appears to be well suited to utilize fatty acids rather than ketone bodies or carbohydrate.
Cardiovascular responses to catecholamines at 12°C in the American bullfrog (Rana catesbeiana)
Authors: Herman Ceil A. , Robleto Daniel O. , Mata Paula L. , Heller R. Scott 
Published: June 2005

AbstractThe effects of epinephrine, norepinephrine, phenylephrine, and isoproterenol on blood pressure and heart rate were studied in cannulated American bullfrogs, Rana catesbeiana. The bullfrogs were chronically cannulated with a T cannula in the right sciatic artery. In warm‐acclimated (22°C) bullfrogs, preinjection mean systemic arterial pressure (SAP) prior to experimental treatment was 13.1 ± 0.7 mm Hg. Preinjection heart rate was 34.8 ± 1.8 beats per minute. These parameters were lower in cold‐acclimated (12°C) bullfrogs. Cold‐acclimated animals had mean SAP values of 8.2 ± 0.3 mm Hg, and heart rate was 11.1 ± 1.1 beats per minute. Epinephrine, norepinephrine, and phenylephrine increased blood pressure to an equivalent degree in warm‐and cold‐acclimated animals. Dose‐related decreases in heart rate in response to these catecholamines were observed in warm‐ but not in cold‐acclimated bullfrogs. Warm‐acclimated animals were more responsive to isoproterenol from 0.03 μg/kg body weight (bw) to 10 μg/kg bw than were cold‐acclimated animals. The response to isoproterenol was effectively blocked by propranolol (5 mg/kg bw) in both warm‐ and cold‐acclimated animals. Propranolol alone decreased mean SAP in both warm‐ and cold‐acclimated animals, suggesting blockade of endogenous sympathetic activity. Beta receptor response thus appears diminished, but not absent at 12°C. However, the alpha receptors responsible for elevation of blood pressure equally responsive at 12° and 22°C.
Analysis and function of organic matrix from sea urchin tests
Authors: Swift Debbie M. , Sikes C. Steven , Wheeler A. P. 
Published: June 2005

AbstractThe organic matrix from sea urchin tests was extracted using 2% acetic acid. This material contained 81–85% protein, 14–19% carbohydrate, and < 1% phosphate. The whole matrix was separated into aqueous soluble and insoluble fractions to determine their individual characteristics and functional activities. Electrophoresis of the soluble matrix (SM) resulted in a single band of approximately 170kD. The SM was capable of inhibiting in vitro CaCO3 precipitation (at nanomolar concentrations) in solutions supersaturated with Ca2+ and CO32‐. It was also capable of inhibiting CaCO3 spicule formation in sea urchin larvae at 10 μg SM per ml of larvae as measured by 14C incorporation. The insoluble matrix (IM) fraction had a higher protein content than the SM component and a lower PO4 content.That the SM from urchin tests is capable of inhibiting both in vitro crystallization and organismal calcification lends credence to its probable role as a mineralization regulator. What role it plays in vivo can only be surmised at this point, and whether or not this role is the same when it acts in conjunction with other components of matrix is unknown.
A new, early, morphological indication of sex differentiation in anura, Rana japonica and R. nigromaculata
Authors: Shirane Terukiyo 
Published: June 2005

AbstractThe genital ridges and gonads of normally developing and testosterone‐treated young larvae of Rana japonica and R. nigromaculata were examined histologically. Two classes of primitive gonads were recognized in both species, one with large germ cells and the other with small germ cells. Testosterone‐treated animals all had gonads with small germ cells. From this and other observations, it is concluded that gonads with large germ cells differentiate into ovaries and those with small germ cells differentiate into testes.
Isolation and partial characterization of the plasma membrane from human spermatozoa
Authors: Mack S. R. , Everingham J. , Zaneveld L. J. D. 
Published: June 2005

AbstractEjaculated human spermatozoa were subjected to nitrogen cavitation (600 psi for ten min) to remove the plasma membrane (PM). Electron microscopic examination of the cavitated cells revealed that 33% of the PM was removed from the sperm which includes both the head and tail regions.The released membrane was separated from the cavitated cells by centrifugation followed by a discontinuous sucrose density gradient centrifugation. A single membrane population was resolved at the 1.0 M sucrose interface. Examination of the isolated membranes by electron microscopy revealed vesicles of various sizes displaying unit membrane structures. Biochemical analysis of the isolated membranes showed a threefold enrichment in the surface membrane marker 5′ nucleotidase and also suggested little contamination by enzymes from the cytosol (lactate dehydrogenase) or mitochondria (cytochrome oxidase). Analytical lipid analysis of the isolated membranes revealed a 26‐fold enrichment in the distribution of cholesterol, an 11‐fold enrichment of phospholipids, and a cholesterol:phospholipid molar ratio of 0.83. Also found was a twofold increase in glycosphingolipids which are ubiquitous components of PM in eukaryotic cells. These data indicate that the membrane vesicles isolated after nitrogen cavitation are primarily PM.
The action of acetylcholine upon heart rate changes markedly with development in bullfrogs
Authors: Burggren Warren , Doyle Michael 
Published: June 2005

AbstractDose‐response curves for the action of acetylcholine (ACh) and its antagonist, atropine, upon heart rate in situ were made for three larval stages and adults of the bullfrog, Rana catesbeiana. The absolute magnitude of heart rate inhibition at any ACh concentration progressively increased throughout larval development. Unexpectedly, metamorphosis to the adult resulted in a sharp decrease in cholinergic cardiac sensitivity down to levels similar to the earliest larvae. Thus, cholinergic sensitivity of heart rate, reflecting properties of the cardiac pacemaker, is greatest immediately before metamorphosis and lowest in early larvae and adults.
Sensory projection patterns of supernumerary legs and aristae in D. melanogaster
Authors: Lienhard Markus C. , Stocker Reinhard F. 
Published: June 2005

AbstractThe central projection patterns of afferents from normal and duplicated legs and antennal aristae in D. melanogaster were established by horseradish peroxidase or cobalt labelling. Duplications were obtained genetically, by using l(1)ts726 and engrailed mutants, which are known to produce supernumerary legs and aristae, respectively. In normal legs, afferents from singly innervated mechanoreceptive (M‐) bristles terminate in the lateral and medial periphery of the corresponding leg neuromere. The medial periphery is also occupied by terminals of multiply innervated chemoreceptive (C‐) bristles; another target of C‐bristles is the anterior margin of the neuromere. The sensory projection patterns of homologous M‐bristles on different leg segments are overlapping, suggesting that terminals are not ordered according to the proximo‐distal location of their cell bodies on the leg. The sensory projections of duplicated legs or aristae overlap the corresponding normal projections. However, when stimulating supernumerary legs in the proboscis extension paradigm, the frequency and intensity of reflex activity are significantly reduced compared to normal legs. These data suggest that normal and supernumerary afferents compete with one another in a subtle way which is not accompanied by gross morphological changes of the projection patterns.
Anatomy of axolotl flank integument during limb bud development with special reference to a transcutaneous current predicting limb formation
Authors: Borgens Richard B. , Callahan Linda , Rouleau M. F. 
Published: June 2005

AbstractWe have compared the anatomy of immature axolotl integument from limb‐forming regions with adjacent non‐limb‐forming regions of the flank, concentrating on the earliest stages of limb bud development. We have extended these observations to include prominent buds just prior to their differentiation. At the ultrastructural level, we note striking differences between these two regions of skin, including a complete loss of hemidesmosomes and tonofilaments in the basal cells of the epidermis; a marked deterioration of the basal lamella; and focal areas of desquamating cells in the apical regions of the bud—all characteristics of limb‐forming regions. These observations were made in the same larvae which provided measurements of a steady endogenous electric (ionic) current that either was coincident with or predicted the area of limb bud outgrowth (Borgens et al.: J. Exp. Zool. 228:491–503, 1983). We discuss these physiological measurements, the changes in the anatomy of the bud‐forming region, and the relevance of these observations to our theory of early limb formation.
Stage‐specific expression of β‐1, 3‐glucanase in sea urchin embryos and hybrids
Authors: Peeler Margaret Truschel , Chambers Scott A. , Wang Chun‐Yen , McClay David R. 
Published: June 2005

AbstractIn some species of sea urchin, such as Lytechinus variegatus β‐1, 3‐glucanase activity is present at two distinct developmental stages (in the unfertilized egg and again following gastrulation). There is a different form of the enzyme β‐1, 3‐glucanase specific to each stage, and these forms can be distinguished immunologically and biochemically. The distinguishing characteristics of the egg and embryonic enzymes were used to analyze the forms of β‐1, 3‐glucanase present in other species that express activity at only one of the two stages. The enzyme present in Tripneustes esculentes, which has activity only early in development, is an 80,000 dalton enzyme antigenically similar to the egg enzyme in Lytechinus. The enzyme present following gastrulation in Echinometra lucunter, however, is distinct from the egg enzyme and is similar to the embryonic enzyme in Lytechinus, despite the absence of activity in the eggs of Echinometra. These results indicate the two forms of β‐1, 3‐glucanase (egg and embryonic) are expressed independently and in a stage‐specific manner, suggesting they are not functionally equivalent. β‐1, 3‐glucanase ase activity was also analyzed in interspecific hybrids. Tripneustes esculentes (which normally lacks the embryonic form) suppressed the expression of the embryonic enzyme in crosses with Lytechinus variegatus (which normally does express it). This suppression occurred whether the Tripneustes genetic material was maternal or paternal in origin. However, the embryonic enzyme normally expressed by Echinometra was expressed in crosses of this species with Tripneustes, i.e, Tripneustes did not suppress enzyme expression in these hybrids. This differential effect on the expression of the embryonic stage enzyme in these hybrids suggests that the mechanisms leading to the expression of this enzyme differ in Lytechinus and Echinometra, despite the biochemical similarities of the enzyme.
Development of spontaneous motility in the guppy embryo (Lebistes reticulatus) and the effect of spinal transection
Authors: Richards Cheryl , Pollack Emanuel D. 
Published: June 2005

AbstractGuppy (Lebistes reticulatus) embryos pass through a distinct sequence of motor behaviors that leads to swimming capability during the course of their development. We have characterized these activities in order of appearance, with several corresponding morphological features, as belonging to the coil stage, tail‐twitch stage, S‐movement stage, and swimming stage. A primary feature of development was an increase in the amount of activity per unit of time over these four stages. The developmental pattern of motility was not interrupted by spinal transection until the onset of swimming, implying that supraspinal information is not required for the occurrence of the primitive behaviors that precede swimming. Elimination of swimming by spinal transection did not elicit a reversion to less complex activities, suggesting that once the cerebral control for swimming is developed, it represents a hardwired system not behaviorally reducible to antecedent components.
Comparative thyroid function in adult Japanese quail and Ring doves: Influence of dietary iodine availability
Authors: McNichols M. J. , McNabb F. M. Anne 
Published: June 2005

AbstractThyroid function was studied in Japanese quail, Coturnix japonica, and Ring doves, Streptopelia risoria, when both were fed the same dietary iodine (I; 930 μg I/kg). We also compared thyroid function in groups of doves receiving low I (< 100 μg I/kg) or moderate I (930 μg I/kg). We measured thyroid gland (TG) weight, TG stable I content, TG 125I uptake, and 125I labeling of thyroid hormones. Triiodothyronine (T3) and thyroxine (T4) concentrations in TGs and serum were also determined. Our results indicate that doves and quail receiving the same dietary I show similar serum T3 (the presumed metabolically active hormone) and TG functional state but that there are some differences between the species in the way in which this functional state is achieved.We also assessed the effects of differences in I availability on thyroid function in doves. With low dietary I doves show decreases in some measures of thyroid function (reduced serum T4 and TG‐hormone stores) compared to doves with moderate I but maintain a comparable level of serumT3. This regulation of T3 appears to be independent of serum T4 or TG‐hormone stores.
Photoperiodic variation of Leydig cell numbers in the testis of the golden hamster: A possible mechanism for their renewal during recrudescence
Authors: Hardy Matthew P. , Mendis‐Handagama S. M. L. C. , Zirkin Barry R. , Ewing Larry L. 
Published: June 2005

AbstractGolden hamster testes regress after short day exposure. The present study asks: 1) are Leydig cell numbers depleted during short days, and 2) if so, how are they replenished during recrudescence. Control hamsters were shown 14 h of light and 10 h of dark (LD 14:10) for 10 weeks (n = 12). Testicular regression was induced by LD 6:18 for 10 weeks (n = 4), and recrudescence by switching regressed hamsters to LD 14:10 for 3 and 5 weeks (n = 8 for each group). All hamsters were injected with [3H]thymidine [3 μCi/gm body wt., intraperitoneally (i.p.)] 1 h or 2 weeks before sacrifice. Leydig cell number per testis was determined by stereological analysis of sections of perfusion‐fixed testes, and labeling indices were determined by autoradiography. Leydig cell numbers were reduced significantly from 18.2 × 106 in control to 9.0 × 106 in regressed testes (p < 0.05); then increased to 14.0 × 106 and 17.9 × 106 in 3‐ and 5‐week recrudesced hamsters. The labeling index was nondetectable (n.d.) for regressed hamsters. In control and recrudescing hamsters the labeling index was measured at two times (t1 = 1 h vs. t2 = 2 weeks post‐injection): in controls, t1 = 0.22 ± 0.15% (mean ± SEM) vs. t2 = 0.28 ± 0.22%; in 1 week recrudesced, n.d. vs. 1.92 ± 0.77% (p < 0.05); at 3 wk, n.d. vs. 4.58 ± 1.74% (p < 0.05); at 5 weeks, 1.92 ± 0.61% vs. 2.25 ± 0.59%. These results are indicative of the existence of interstitial precursor cells that divide, then differentiate, and thus replenish the Leydig cell population during testicular recrudescence.
Adenylate cyclase and cyclic AMP in the ciliate Euplotes crassus: Involvement in both cell cycle and sexual reproduction
Authors: Verni F. , Rosati G. 
Published: June 2005

AbstractIn this paper the presence and the possible activity of adenylate cyclase‐cyclic AMP (AC‐cAMP) system has been investigated through cell cycle and sexual reproduction of the ciliate Euplotes crassus. For this purpose cytochemical studies for AC demonstration at the ultrastructural level were carried on. Moreover, “in‐vivo” experiments were performed by adding different substances to the cell cultures: alloxan (inhibitor of AC), theophylline (inhibitor of phosphodiesterase), exogenous cAMP, and cholera toxin (which maintains AC in an active state). The results obtained are indicative that cAMP is a “regulatory factor” acting during cell cycle as E. crassus cells are not able to undergo macronuclear DNA synthesis in the presence of theophylline. As concerns sexual reproduction both cytochemical observation and “in‐vivo” experiments are suggestive of a rapid activation of AC upon mixing strains of different mating types. This activation, which lasts only for the initial part of the waiting period, appears to be necessary for pair formation.
Antigenic comparison of five species of mammalian zonae pellucidae
Authors: Maresh Grace A. , Dunbar Bonnie S. 
Published: June 2005

AbstractA comparison of glycoproteins of the zona pellucida (ZP) of five different mammalian species (cat, dog, rabbit, pig, and rat) has been made using polyclonal and monoclonal antibodies. In an enzyme‐linked immunosorbent assay (ELISA), polyclonal antisera against total rabbit and pig ZP recognize their homologous ZP to the greatest extent but also detect crossreactive antigenic determinants in the ZP of all other species tested. Polyclonal antibodies against each of two purified rabbit ZP glycoproteins or one purified pig ZP glycoprotein also show some recognition of heterologous (pig, cat, and dog) ZP, but not rat ZP. Monoclonal antibodies (McR5‐rabbit ZP protein determinant; McPSI‐determinant associated with post‐translational modifications of pig ZP proteins such as carbohydrates) further demonstrate that specific determinants are shared between some but not all of these mammalian species. For example, both of these antibodies recognize distinct determinants which are most abundant in pig and cat ZP. However, McR5 recognizes a determinant on all species of ZP except the rat, while McPSI does not recognize either the rabbit or rat ZP. Collectively, these studies suggest that the molecules of the pig, dog, and cat ZP are more closely related to each other than to those of the rabbit ZP, while there is little similarity with rat ZP molecules. Immunoblot analysis of ZP glycoproteins separated by two‐dimensional polyacrylamide gel electrophoresis was used to identify antigenic relationships among four different species. The polyclonal antisera show that all of the major proteins of pig, rabbit, cat, and dog ZP are antigenically related. These studies provide information that is important for the comparison of structural and functional similarities and dissimilarities in the molecular components of the mammalian zona pellucida that are involved in the fertilization process.
Methionine and iron as growth factors for rat embryos cultured in canine serum
Authors: Flynn Thomas J. , Friedman Leonard , Black Thomas N. , Klein Norman W. 
Published: June 2005

AbstractDevelopment of headfold‐staged rat embryos cultured in canine serum containing various supplements was compared with development in rat serum to seek suitable alternatives to rat serum in rodent embryo culture and to identify nutritional factors for cultured rodent embryos that may have relevance for normal mammalian embryonic growth and development. Supplementation of canine serum with glucose, methionine, and a lipophilic iron chelate allowed growth and development of cultured rat embryos, approximating those obtained with rat serum. These findings suggest that properly supplemented canine serum can serve as a suitable rodent embryo culture medium and that glucose, iron, and methionine may be important nutrients in mammalian embryonic development.