bluuebunny/crossref_metadata_2025_split huggingface dataset:
New insights into the anhydrobiotic phenomenon: The effects of trehalose content and differential rates of evaporative water loss on the survival of Aphelenchus avenae
Authors: Higa Lynne M. , Womersley Christopher Z. 
Published: June 2005

AbstractThe effects of differential rates of evaporative water loss on the survival capabilities of small aggregates (ca. 10 mg wet wt) of Aphelenchus avenae were assessed. This was achieved using a comparative approach between rapid (direct transfer of preconditioned nematodes to successively compounds accumulated were also assessed during the induction process. Glyecrol and glucos levels remained low (< 1% dry wt)) while trehalose levels increased dramatically during preconditioning (8–10% dry wt), but the elevated levels were unable to support survival during periods of rapid water loss. Survival was directly related to the rate of evaporative water loss, with the highest level of survival being afforded by the most gradual dehydration regime. In addition, the water loss curves identified a critical period where hydration levels ranged from 40% to 12% H2O. During this time, slow drying was essential if the nematodes were to successfully survive the dehydration process. Survival curves also revealed the existence of a transition phase in the dehydration process, where nematodes required further dehydration before revival could occur. These results are discussed in relation to the adaptive significance of polyhydroxy compound accumulation and the probable role that specific hydration levels play in the implementation of other adaptations at the cellular and subcellular levels. © 1993 Wiley‐Liss, Inc.
Prostaglandin E2 and prostaglandin F2α involvement in the corticosterone and cortisol release by the female frog, Rana esculenta, during ovulation
Authors: Gobbetti Anna , Zerani Massimo 
Published: June 2005

AbstractInterrenal and ovarian tissues of Rana esculenta were incubated in vitro during the preovulatory, ovulatory and postovulatory phases to study the basal release of prostaglandin E2 (PGE2), prostaglandin F2α, (PGF2α), corticosterone, and cortisol. The effects of exogenous PGE2 and PGF2α on interrenal and ovarian corticosteroid release were also studied. In addition, the plasma values of these four hormones were assessed during the same phases. During in vitro interrenal incubations, PGE2α PGF2α, corticosterone, and cortisol basal releases were higher in the postovulatory phase, PGE2, and PGF2α treatment in vitro increased corticosteroids during the ovulatory phase. During in vitro ovarian incubations, PGE2 basal release was higher in the preovulatory phase and PGF2α and corticosteroids in the ovulatory phase; PGE2 treatment in vitro decreased corticosteroids in the ovulatory phase, and PGF2α increased corticosteroids in the preovulatory and postovulatory phases. PGE2, corticosterone and cortisol plasma values were higher during the postovulatory phase, while PGF2α, was elevated during the ovulatory phase. These findings suggest that ovarian corticosteroids could be considered one of the factors inducing ovulation and that their synthesis may be modified by PGs. © 1993 Wiley‐Liss, Inc.
Pedicle and antler development following sectioning of the sensory nerves to the antlerogenic region of red deer (Cervus elaphus)
Authors: Li Chunyi , Sheard Philip W. , Corson Ian D. , Suttie James M. 
Published: June 2005

AbstractSensory nerves supplying the deer antlerogenic region were sectioned about 60 days prior to pedicle initiation to determine the extent of neural influence on pedicle and first antler growth. Our results from a combination of histological examination and immunohistochemical localization showed that all 12 antlerogenic regions were successfully deprived of sensory nerve supply, but in 10 of 12 cases there was partial regeneration during the experimental period. In the two cases where no sensory reinnervation occurred, pedicle growth did not show any differences compared with partially sensory reinnervated or intact pedicles. With or without reduced sensory nerve supply, first antlers were initiated, grown, cleaned of velvet, cast, and regenerated in the normal way, but they were smaller than controls. Consequently, we conclude that a sensory nerve supply is not necessary for normal pedicle formation and for the first antler cycle, but plays a role in determining antler size. © 1993 Wiley‐Liss, Inc.
Characterization of equine oviductal proteins synthesized and released at estrus and at day 4 after ovulation in bred and nonbred mares
Authors: McDowell Karen J. , Adams Mary H. , Williams Neil M. 
Published: June 2005

AbstractProteins synthesized and released in vitro by oviducts collected from horse mares during estrus and at day 4 after ovulation for bred and nonbred mares were examined by two‐dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (2‐D SDS PAGE) and fluorography. Ampullary and isthmic regions both produced a wide array of nondialyzable proteins in culture. Major proteins or groups of proteins identified according to relative molecular weight (kDa) and apparent isoelectric point (pI) were at 100kDa, PI8; 100–200 kDa, PI6; 150 kDa, PI4.5;60–100 kDa, PI 4; and an array of polypeptides at 21–22 kDa, pI 5–6. Oviductal secretory activity, measured by incorporation of radiolabeled amino acids into nondialyzable macromolecules released into incubation medium, was greater (P <.01) for the ampullary than the isthmic oviductal region. No consistent differences were observed in fluorograms between estrus vs. day 4 after ovulation, ampulla vs. isthmus, ipsilateral vs. contralateral to the corpus luteum or largest follicle, oviducts from bred vs. nonbred mares, or mare ages. Dialyzed medium from ampullary and isthmic regions of oviducts was subjected to 1‐D or 2‐D SDS PAGE followed by western blotting utilizing an antiserum directed against human retinol binding protein (RBP). The family of 21–22 kDA polypeptides was identified as immunoreactive RBP. © 1993 Wiley‐Liss, Inc.
Problems in the understanding of cell volume regulation
Authors: Macknight A. D. C. , Gordon L. G. M. , Purves R. D. 
Published: June 2005

AbstractThe constancy of cell volume under physiological conditions is generally thought to reflect a balance between solute influx and efflux and is therefore critically dependent on the properties of the plasma membrane. Despite a number of unanswered questions, a large amount of experimental data can be accommodated within this pump‐leak framework and can by analysed using the simple assumptions of osmotic equality between cells and their surrounding fluid, and fluid electroneutrality. Experimentally, cell volume may be altered in vitro either by changing cell solute content under isosmotic conditions or by changing medium osmolality. Exposure to anisosmotic media may provoke a variety of cell responses that minimise the volume change. However, much of this experimental work has been performed under extreme conditions in vitro that would never be experienced by vertebrate cells in vivo; its relevance to pathophysiological situations is questionable. It is argued that regulation of cell volume should not be seen in isolation but as part of the process, cell homeostasis, by which cells attempt to minimise changes in composition when faced with perturbations in their environment. Given the variety of processes and the large numbers of membrane transporters, an understanding of how cells respond to such perturbations requires a combination of modelling and experimentation. A simple example of this approach is presented. © 1994 Wiley‐Liss, Inc.
Evidence for the role of actin filaments in regulating cell swelling
Authors: Mills John W. , Scwiebert Erik M. , Stanton Bruce A. 
Published: June 2005

AbstractActin filaments could play a role in regulation of cell swelling by two distinct mechanisms. One is by a tensile mechanism involving the coordinated interaction of actin and actin‐associated proteins with all plasma membrane domains. The actin‐membrane linkage would restrain cell swelling in the event of the influx of water. In shark rectal gland cells, conditions that cause massive cell swelling (i.e., high K medium, exposure to mercurials) are associatd with disruption of membrane‐associated actin filaments. Under conditions that result in only moderate swelling (Na‐pump inhibition, Li substitution) the actin filaments remain associated with the cell membrane. Thus, in this cell type, disruption of the actin‐membrane organization is correlated with increased swelling. Another mechanism by which actin could limit cell swelling is via regulation of ion transport proteins that are activated by cell swelling. This could be accomplished by a vesicle transport and insertion mechanism that delivers ion transport units to the cell membrane or by interaction with transport proteins already present in the membrane. Cell‐attached patch clamp studies of RCCT‐28A cells exposed to hypotonic medium demonstrated the activation of Cl‐channel activity coincident with an alteration in actin. Activation of the channel was mimicked by stretching the membrane. Exposure of inside‐out patches to cytochalasins also increased Cl‐channel activity. Treatment of isolated patches with phalloidin inhibited stretch‐induced activation. Thus, regulation of a volume‐sensitive Cl‐channel appears to be directly related to the state of organization of actin filaments. © 1994 Wiley‐Liss, Inc.
Volume‐activated amino acid transport and cell signaling in skate erythrocytes
Authors: Goldstein Leon , Musch Mark W. 
Published: June 2005

AbstractSkate (and other fish) erythrocytes show a rapid efflux of taurine in response to volume expansion upon exposure to hyptonic medium. Taurine and other small amino acids appear to be released from the cells down their concentration gradients via a channel which might involve the anion exchange protein Band 3. Hypotonicity alters the cell permeability to taurine coincident with generation of diacylglycerol from phosphatidylcholine by stimulating the activity of phospholipase D. This diacylglycerol can then activate protein kinase C, stimulating the phosphorylation of specific protein targets. Three phosphoprotein targets have been identified; one is the Band 3 molecule itself, while the other two have molecular weights of 67 and 34 kDa. The precise way in which phosphorylation alters the permeability of the cell to taurine is as yet unknown. It is possible that phosphorylation of Band 3 changes the molecule so that it acts as an amino acid channel. © 1994 Wiley‐Liss, Inc.
Molecular basis for osmoregulation of organic osmolytes in renal medullary cells
Authors: Burg Maurice B. 
Published: June 2005

AbstractRenal medullary cells are naturally exposed to extremely high and variable interstitial concentrations of NaCl and urea, consequent to operation of the urinary concentrating mechanism. They respond by accumulating large and variable amounts of sorbitol, glycerophosphocholine (GPC), glycine betaine (betaine), myo‐inositol (inositol), and taurine both in vivo and in cell cultures. Sorbitol is synthesized from glucose, catalyzed by aldose reductase. Hypertonicity increases aldose reductase activity by raising this enzyme's transcription, mRNA level, and translation, and thereby increases production of sorbitol. GPC is synthesized from choline via phosphatidylcholine. A combination of high NaCl plus urea does not increase GPC synthesis, but does reduce its degradation by inhibiting GPC:choline phosphodiesterase. Betaine, inositol and taurine are taken up into the cells, each by a different sodium‐dependent transporter. Hypertonicity increases mRNAs of all three transporters. This is due to increased transcription (at least of the inositol and betaine transporters). The eventual result is greater betaine, inositol and taurine uptake and accumulation. Osmoregulation of net sorbitol and GPC synthesis and of betaine, inositol and taurine transport is slow, requiring hours to days. However, following an acute fall in tonicity, these organic osmolytes exit from the cells within minutes, via specialized efflux mechanisms. As demonstrated by cloning efficiency studies, renal cell survival and growth following hypertonicity depend on the sum of all organic osmolytes that are accumulated; altering one experimentally changes the others to maintain a nearly constant total. Methylamine accumulation protects these cells against high urea; the methylamine that is preferentially accumulated in response to high urea is GPC. © 1994 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
Frequency and amplitude tuning of nematocyst discharge by proline
Authors: Watson Glen M. , Hudson Renee R. 
Published: June 2005

AbstractIn sea anemone tentacles, discharge of nematocysts into vibrating targets is regulated by hair bundles. N‐acetylated sugars are known to induce hair bundles to elongate while tuning nematocyst discharge to low frequencies and small amplitudes corresponding to movements produced by calmly swimming prey. Proline is known to induce hair bundles to shorten while tuning nematocyst discharge to higher frequencies. In this report, we provide evidence suggesting that proline linearly tunes nematocyst discharge. Nematocyst discharge is tuned by increases of 10−18 M proline above background levels ranging from 10−12 M to 10−8 M proline, but only after anemones adapt to the background levels of proline. Anemones adapt more rapidly to 10−12 M proline than to 10−10 M, followed by 10−8 M proline. L‐proline and D‐proline comparably tune nematocyst discharge. Proline tunes discharge to higher frequencies and/or to larger amplitudes at the same lower frequencies produced by prey. We propose that N‐acetylated sugars tune nematocyst discharge to the movements of calmly swimming prey. After the prey is wounded by nematocysts, it releases proline into the seawater. This proline tunes nematocyst discharge to higher frequencies and/or larger amplitudes at low frequencies corresponding to movements produced by struggling, wounded prey. Thus, the greatest numbers of nematocysts may be discharged into calmly swimming, fresh prey and into vigorously struggling, wounded prey. © 1994 Wiley‐Liss, Inc.
Effect of air exposure on ammonia excretion and ammonia content of branchial water of the crab Cancer pagurus
Authors: Regnault Michèle 
Published: June 2005

AbstractC. pagurus (mean weight 280 g) was exposed to air for 18 h at 16–18°C in presence of a small volume of filtered seawater (FSW = 45 ml) and then reimmersed. Ammonia excretion rate was measured and the amount of ammonia that accumulated in branchial water and haemolymph during emersion was evaluated. During the whole emersion period, ammonia that was released into both FSW (42 μmoles·crab−1) and branchial water (< 11 μmoles·crab−1) amounted to 6% of the pre‐emersion release, at the very most.In the first 5 min immediately following reimmersion, a large burst of ammonia output (203 μmoles·crab−1) was observed. Neither ammonia stored in branchial water and haemolymph nor breakdown of urate accumulated in haemolymph can account for it. As this burst was not the result of an increase in metabolism only, its potential sources are discussed. Following this burst, ammonia excretion rate returned to its pre‐emersion value within the next 1 h. Then, ammonia excretion rate again increased; this second increase was relatively moderate and lasted for 2–3 h. Recovery was fully achieved within 8 h. The ammonia excess that was excreted during recovery was mainly released at the onset of re‐immersion. © 1994 Wiley‐Liss, Inc.
Immunological identification and biochemical characterization of a glucose transporter in the posterior gills of the crab Carcinus maenas (L.)
Authors: Welcomme L. , Devos P. 
Published: June 2005

AbstractThe euryhaline crab Carcinus maenas when adapted to hyposmotic medium shows an ion transporting‐type epithelium in the three posterior gills. When they are perfused in hyposmotic conditions, there is highly specific sodium‐independent glucose transport activity. This saturable transport activity is inhibited by phloretin and diethylstilbestrol.Immunological data obtained with the utilization of the antibody RaIRGT (antibody anti‐glucose transporter found in rat adipocytes) reveals the existence of a single bound protein of 38 Kd. This protein can specifically bind to cytochalasin B which has a high affinity for the glucose transporter found in numerous tissues of vertebrates.These biochemical and immunological data point to the existence of a glucose transporter of 38 Kd in the branchial tissue of this species of crab. © 1994 Wiley‐Liss, Inc.
Spinal cord neurite growth response to target tissue in a dose‐dependent manner in vitro
Authors: Somasekhar Thummala , Pollack Emanuel D. 
Published: June 2005

AbstractNeurite outgrowth from larval frog spinal cord explants in tissue culture previously has been shown to be enhanced and oriented in the presence of mesenchymal limb target tissue. Evidence that suggests the limb mesenchyme is the source of a motor neuron growth factor has prompted consideration of a possible target dose relationship in eliciting spinal neurite growth. Whereas typical experimental paradigms incorporate a single target explant in cocultures of neural and target tissues, we have challenged spinal cord explants with dual limb targets. Both the spinal cord explants and mesenchymal limb tissue segments were derived from young stage V Rana pipiens tadpoles. In comparison to cultures with a single limb, the spinal neurite density in the presence of two limbs increased more than twofold. Accompanying the increase in neuritic quantity was a substantial increase in the average length of the neurites. Over a two‐week culture period there was little change in the relative differences between the single and double target cultures. Even though the double target tissues were placed adjacent to one another on one side of the cord explant, greatly enhanced neurite growth occurred on the contralateral side as well. The dramatic increase in neurite outgrowth in the presence of an additional target tissue provides further evidence that undifferentiated mesenchymal limb tissue is the source of a spinal neurite growth‐promoting factor that may act in a dose‐dependent manner with implications for both motor axon growth regulation and regeneration. © 1994 Wiley‐Liss, Inc.
Mouse trophoblast cell invasion of extracellular matrix purified from endometrial tissue: A model for peri‐implantation development
Authors: Armant D. Randall , Kameda Shogo 
Published: June 2005

AbstractWe have investigated the invasive activity of mouse trophoblast cells during embryo implantation in vitro by culturing blastocysts with extracellular matrix (ECM) purified from mouse endometrium obtained on day 4 of pregnancy Endometrium was dissected from lyophilized mouse uteri, and intact ECM was isolated by sequential precipitation in nonionic detergent and high salt. Electron microscopic examination of the ECM revealed typical collagen fibers plus an amorphous material resembling basement membrane. Electrophoretic analysis of the ECM revealed an enrichment of high molecular weight proteins, and immunoblotting indicated the presence of fibronectin, laminin, entactin, and type IV collagen, but not the intracellular proteins 2′,3′‐cyclic nucleotide‐3′‐phosphodiesterase or vimentin. Mouse blastocysts cultured with this ECM attached to it within 3 days, and the trophoblast cells began to migrate through the matrix in a manner resembling trophoblast invasion in utero. Unlike blastocysts cultured on plastic surfaces, the trophoblast did not flatten and become disorganized, but retained a polarized, spherical structure. Fluorescent microscopy with fluorescein isothiocyanate‐labeled phalloidin revealed a high degree of microfilament organization and established that actin was absent from the ECM preparation. In the presence of a serum substitute, differentiation continued through yolk sac formation. Without serum components, yolk sac did not form; however, light and electron microscopic examination indicated that the invasive behavior of trophoblast cells persisted and was comparable to that of trophoblasts cultured in the presence of the serum substitute. A three‐dimensional model for investigating trophoblast behavior in ECM from the endometrium should be of great value in elucidating the cellular and molecular events surrounding the process of blastocyst implantation. © 1994 Wiley‐Liss, Inc.
Gravity in mammalian organ development: Differentiation of cultured lung and pancreas rudiments during spaceflight
Authors: Spooner Brian S. , Hardman Patricia , Paulsen Avelina 
Published: June 2005

AbstractOrgan culture of embryonic mouse lung and pancreas rudiments has been used to investigate development and differentiation, and to assess the effects of microgravity on culture differentiation, during orbital spaceflight of the shuttle Endeavour (mission STS‐54). Lung rudiments continue to grow and branch during spaceflight, an initial result that should allow future detailed study of lung morphogenesis in microgravity. Cultured embryonic pancreas undergoes characteristic exocrine acinar tissue and endocrine islet tissue differentiation during spaceflight, and in ground controls. The rudiments developing in the microgravity environment of spaceflight appear to grow larger than their ground counterparts, and they may have differentiated more rapidly than controls, as judged by exocrine zymogen granule presence. © 1994 Wiley‐Liss, Inc.
Role of epidermal–dermal tissue interactions in regulating tenascin expression during development of the chick scutate scale
Authors: Shames Rose B. , Bade Belinda C. , Sawyer Roger H. 
Published: June 2005

AbstractDuring normal chicken development tenascin begins to accumulate in the dermis of anterior metatarsal skin at the time of scutate scale ridge formation, and is localized in a distinct pattern along the outer scale surface. Anterior metatarsal skin from scaleless (sc/sc) embryos, which do not form scutate scales, begins to accumulate tenascin 4 days later than normal skin. This study shows that normal and scaleless anterior metatarsal dermis accumulate the same tenascin isoforms and undergo the same isoform changes in the post‐hatch period, but there is less tenascin accumulated in scaleless dermis and there is no pattern to its distribution. In both normal and scaleless anterior metatarsal skin, tenascin mRNA is localized in the dermis and is distributed in the same way as the protein. Thus, scaleless skin is defective in the ability to accumulate appropriate amounts of tenascin and to maintain the tenascin in the patterned manner of normal. Recombinant skin cultures show that epidermal–dermal interactions are required for tenascin accumulation. The dermis specifies the way that tenascin is organized, but interaction with epidermis is required to maintain this organization. The epidermal role appears to be permissive because in heterotypic recombinants, neither scaleless anterior metatarsal epidermis nor normal footpad epidermis changes the way that tenascin appears in the normal anterior metatarsal dermis; and in reciprocal recombinants, normal anterior metatarsal epidermis does not change the way tenascin is accumulated in either scaleless anterior metatarsal dermis or normal footpad dermis. © 1994 Wiley‐Liss, Inc.