bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gaseous ammonia evolution is coupled to reprocessing of urine at the gills of ghost crabs
Authors: De Vries M. C. , Wolcott D. L. 
Published: June 2005

AbstractUrine of terrestrial and aquatic crabs generally is of neutral pH and contains negli‐gible waste nitrogen. Ammonia is added to urine during its reprocessing by the gills of some terrestrial species. The ghost crab, Ocypode quadrata, produces an acidic urine (pH < 6.0) that is high in ammonia (>100 mM). This prompted us to study the chemical changes which occur during urine reprocessing by this species. Urine and reprocessed urine were collected from fed animals maintained on sand moistened with diluted seawater, and several chemical variables were measured. During urine reprocessing, Cl− was reclaimed, and CO2 concentration and pH increased. Evolution of gaseous ammonia was then measured in crabs which could and could not pass urine onto their gills. Animals with occluded nephropores released gaseous ammonia at a much lower rate (≈︁300 μmol·.kg−1·day−1) than animals with open nephropores (≈︁2,000 μmol·kg−·day−1). We hypothesize that the gaseous ammonia released by control crabs is predominantly due to degassing of NH3 from the fluid (urine) upon the pH increase which occurs during reprocessing by the gills. © 1993 Wiley‐Liss, Inc.
Cold exposure and food restriction facilitate physiological responses to short photoperiod in Djungarian hamsters (Phodopus sungorus)
Authors: Ruf T. , Stieglitz A. , Steinlechner S. , Blank J. L. , Heldmaier G. 
Published: June 2005

AbstractWe investigated the influence of ambient temperature (Ta) and food availability on seasonal timing and extent of physiological responses to short photoperiod (SP), in particular daily torpor, in Djungarian hamsters (Phodopus sungorus). Exposure of hamsters to cold temperature (Ta = 5°C), relative to warm Ta (23°C), resulted in:(1)a significant advance (P < 0.05) of the first occurrence of torpor among cold‐exposed hamsters (days 52–97 vs. days 83–99 in SP); (2) a higher (P < 0.01) incidence of torpor (48% vs. 20% torpid animals/day);(3) a higher (P < 0.05) degree of molt into the winter pelt; and (4) an accelerated reduction of body weights (P < 0.001). However, within SP/cold‐Ta exposed groups, individual hamsters clearly showed different tendencies for torpor (torpor on 0–95% of days observed). Therefore, we evaluated the effects of small changes in Ta on torpor frequency and extension by subjecting the same SP‐adapted individuals to varying temperatures. Lowering of Ta from 15°C to 10°C and 5°C caused significant (P < 0.05) increases in the incidence of torpor (20%, 33%, and 40%, respectively) and lower minimal body temperatures during hypothermia (P < 0.05). When the same animals were subjected to 24–48 h lasting periods of food restriction (60% of the ad libitum intake), torpor frequency further increased 1.8to 2.6‐fold at all Tas.These results show that Ta and food availability are effective in modifying both seasonal timing and extent of photoperiodically controlled adaptations. This integration of multiple environmental cues, combined with a pronounced within‐species variability of winter adjustments, indicates that Djungarian hamsters are capable of flexible physiological responses towards unpredictable climatic changes in the environment. © 1993 Wiley‐Liss, Inc.
The wound epithelium of regenerating limbs of Pleurodeles waltl and Notophthalmus viridescens: Studies with mAbs WE3 and WE4, phalloidin, and DNase 1
Authors: Tassava Roy A. , Castilla Martha , Arsanto Jean‐Pierre , Thouveny Yves 
Published: June 2005

AbstractThe wound epithelium of regenerating limbs of the American newt, Notophthalmus viridescens (Nv), up‐regulates a number of antigens, including those recognized by mAbs WE3 and WE4. In the present study, we show that the WE3 antigen is up‐regulated in a similar fashion in the wound epithelium of the European newt, Pleurodeles waltl (Pw). mAb WE3 and WE4 reactivities to secretory/transport body cell types, including integumentary glands, perineurium, endothelium, and conjunctiva, are also similar in these two species of newt. However, mAb WE4 reacts to both the epidermis and wound epithelium in Pw, whereas in Nv, mAb WE4 reacts only to the wound epithelium. Because the WE3 antigen is cytoskeleton‐associated and Western blots reveal a 43 kDa species, we compared mAb WE3 reactivity with that of rhodamine‐labeled phalloidin, a known actin‐binding compound. Phalloidin did not react preferentially to the wound epithelium, conjunctiva, or other cell types strongly reactive to mAb WE3. Pretreatment of sections and tissue extracts with DNAse 1, a protein known to bind to actin, nearly abolished mAb WE3 reactivity in tissue sections and both WE3 and WE4 reactivity in ELISA assays, respectively. The results lead to the hypothesis that the WE3 and WE4 antigens are actin‐binding proteins unique to the wound epithelium and other secretory/transport cell types. © 1993 Wiley‐Liss, Inc.
Studies of lysophospholipids related to the hamster sperm acrosome reaction in vitro
Authors: Llanos Miguel N. , Morales Patricio , Riffo Marta S. 
Published: June 2005

AbstractPhospholipase A2 and lysophospholipids have been implicated in the mammalian sperm acrosome reaction. In this study we further investigated the role of this enzyme and lysophospholipids on the acrosome reaction of hamster spermatozoa. Hamster epididymal spermatozoa were incubated under capcaitation and acrosome reaction‐inducing conditions. After 3.0 and 3.5 h, the spermatozoa were treated with different doses of lysophosphatidylcholine for 12 min. Then the percentage of motility, hyperactivation, and acrosome reaction was evaluated by light microscopy. Lysophosphatidylcholine, 10 μg/ml, was the highest acrosome reaction‐inducing dose without an effect on sperm motility. Lysophosphatidylcholine induced the acrosome reaction only when added to spermatozoa capacitated for a minimum of 2 h. This effect was apparent after 1 min of its addition and reached a plateau after 5 min. Lysophosphatidylethanolamine and lysophosphatidylinositol were also effective in inducing the acrosome reaction. Lysophosphatidylserine did not have any effect on the reaction, but caused an increase in sperm hyperactivation. Sperm treated with the phospholipase A2 inhibitors quinacrine dihydrochloride and p‐bromophenacyl‐bromide showed an inhibition of the spontaneous occurrence of the acrosome reaction. These inhibitors, however, did not block the acrosome reaction induced by lysophosphatidylcholine. The time course of the lysophosphatidylcholine‐induced acrosome reaction was the same whether control or inhibitor treated spermatozoa were used. These results suggest that the membrane events of the acrosome reaction initiate with the activation of the phosphlipase A2, thus producing the fusogen agents necessary for this exocytotic event. © 1993 Wiley‐Liss, Inc.
Spiral patterns in the micropylar wall and filaments on the chorion in eggs of the medaka, Oryzias latipes
Authors: Iwamatsu Takashi , Nakashima Seiko , Onitake Kazuo 
Published: June 2005

AbstractThe relationship between spiral patterns in the inner wall of the micropyle and attaching and non‐attaching filaments on the chorion was investigated by electron microscopy in eggs of the medaka, Oryzias latipes. There were both right‐ and left‐handed spiral patterns of attaching filaments that arose from the chorion at the vegetal pole area. In the majority of eggs examined, however, the prominent folds in the inner wall of the micropylar vestibule descended toward the micropylar canal in a left‐handed spiral. This spiral pattern in the micropyle may reflect surface indentations in the cytoplasmic extension of the micropylar cell during formation of the micropyle apparatus. The present observations suggest that the patterns of these spiral structures of the chorion are casused by the rotation of the oocyte due to the movement of follicular cells during oogenesis. © 1993 Wiley‐Liss, Inc.
Culture of intact Sertoli/germ cell units and isolated sertoli cells from Squalus testis. II. Stimulatory effects of insulin and IGF‐I on DNA synthesis in premeiotic stages
Authors: Dubois Wilfrid , Callard Gloria V. 
Published: June 2005

AbstractTo investigate growth control mechanisms during spermatogenesis, in vitro, [3H]thymidine incorporation into acid‐insoluble macromolecules was used to quantify DNA synthesis in cultured spermatocysts (intact Sertoli cell/germ cell clones) derived from premeiotic (PrM), meiotic (M), and postmeiotic (PoM) regions of dogfish (Squalus acanthias) testis. Forty‐eight hours after seeding in basal medium, DNA synthesis was >7‐fold higher in PrM cysts than in other stages, thus verifying the staging procedure. In autoradiograms, germ cells of PrM cysts (e.g., spermatogonial and preleptotene stages) were labeled all‐or‐none, but not all cysts were labeled, and later developmental stages (e.g., cysts with round or elongating spermatids) were never labeled. Fetal bovine serum (FBS, 10%) and insulin‐transferrin‐selenite (ITS, 10 μg‐10 μg‐10 ng/ml) doubled DNA synthesis in PrM cyst cultures but had no effect at other stages. Bovine insulin (10 μg/ml) and human recombinant insulin‐like growth factor‐I (IGF‐I, 15 ng/ml) also doubled [3H]thymidine uptake in PrM cultures, but lower doses were less effective and estradiol‐17β, transferrin, adult shark serum, purified shark relaxin, and a variety of other known growth factors were neither stimulatory nor inhibitory at the doses and conditions tested.Sertoli cell monolayers derived from PrM‐ or M‐stage spermatocysts displayed a dose‐response increase in DNA synthesis after addition of IGF‐I (15–75 ng/ml), with a maximal increment significantly greater than with 10% FBS. Using [3H]thyumidine incorporation by PrM cysts as an end‐point, stimulatory bioactivity was detected in the <30, 000 kDa fraction of spent media from PrM Sertoli cells, whereas the low molecular weight fraction of M‐stage Sertoli cells was inhibitory. Gel electrophoretic analysis of the two fractions revealed qualitative and quantitative differences in protein banding patterns, reinforcing the view that secretory activity of Sertoli cells is stage related.Results of these studies implicate insulin/IGF‐I in mechanisms governing proliferation of male germ cells and support the view that Sertoli cells have an autocrine or paracrine role as both targets and sources of growth regulatory factors. © 1993 Wiley‐Liss, Inc.
Changes in membrane potential associated with cell swelling and regulatory volume decrease in barnacle muscle cells
Authors: Berman D. M. , Peña‐Rasgado C. , Rasgado‐Flores H. 
Published: June 2005

AbstractOur aim was to test the effect of hypotonicity and extracellular Ca2+ (Cao) on cell volume and membrane potential (VM) in barnacle muscle cells. Under isotonic conditions the resting VM of isolated cells mounted in the experimental chamber exposed to either Ca2+‐free or Ca2+‐containing (11 mM) solutions was − 46.3 ± 1.0mV (n = 24) and − 56.2 ± 0.9 mV (n = 38), respectively. In the absence of Cao, the cells depolarized at a rate of 2.3 ± 0.47 mV/hr; the presence of Cao reduced this rate of depolarization by 2.9‐fold. Both in the absence or presence of Cao, the cells swelled in response to hypotonicity but underwent regulatory volume decrease (RVD) when Cao was present. Addition of the Ca2+ channel blocker, verapamil (0.1 mM), inhibited the Cao‐dependent RVD. The percentage of cells responding with RVD increased with larger hypotonic challenges. There was a Cao‐independent direct relationship between cell swelling and membrane depolarization which can be explained by dilution of the concentration of intracellular K+ ([K+]i). RVD was accompanied by a small hyperpolarization (3.0 ± 0.38 mV/2 hr) which may represent increases in [K+]i during cell shrinking and activation of a conductive pathway. The results indicate the following: (1) the presence of Cao stabilizes VM; (2) cell swelling produces a depolarization which can be explained by dilution of [K+]i; (3) cell swelling activates a verapamil‐sensitive Ca2+ influx responsible for promoting RVD; and (4) RVD is accompanied by a hyperpolarization which may result from activation of a conductive pathway. © 1994 Wiley‐Liss, Inc.
Channels for ions and amino acids in kidney cultured cells (MDCK) during volume regulation
Authors: Roy Guy , Banderali Umberto 
Published: June 2005

AbstractA cell line from canine kidney (MDCK) was studied in hypotonic conditions to determine the transport mechanisms involved during regulatory volume decrease (RVD). It was found that RVD was related to a loss of K+, Cl− and amino acids. Membrane potential measurements during RVD have shown a hyperpolarization followed by a depolarization, implying that ion fluxes were probably occurring through channels. Quinine was found to inhibit RVD, the ion fluxes and the amino acid losses. A long preincubation in Ca+ + ‐free EGTA medium had no effect on RVD in cells exposed to the hypotonic medium. Single channel experiments with the patch clamp technique have shown that cell swelling rapidly activates K+ channels and, after a 30 sec delay, Cl− channels. The K+ channel was highly selective and had a linear I‐V curve with a conductance of 25 pS. The Cl− channel was an outward rectifier with conductances of 63 and 26 pS. It was not very selective; replacing Cl− with NO3− did not change the I‐V curve and did not affect RVD. The amino acid losses during RVD were studied with HPLC. It was found that three of them, glutamate, taurine and gly‐cine, had large concentrations and were lost at different rates. Their fluxes during RVD depended linearly on their external concentrations, meaning that the transport process was diffusional. Single channel measurements with glutamate, aspartate or taurine in place of Cl− have shown that these amino acid losses occurred through the Cl− channel. © 1994 Wiley‐Liss, Inc.
Osmoregulation in Rhizobium meliloti: Mechanism and control by other environmental signals
Authors: Smith Linda Tombras , Smith Gary M. , D'Souza Marian R. , Pocard Jean‐Alain , Rudulier Daniel Le , Madkour Magdy A. 
Published: June 2005

AbstractBacteria commonly adapt to increases in the osmolarity of the environment by the intracellular accumulation of small organic solutes (osmolytes) that function by restoring turgor. We have investigated the mechanism of osmotic regulation in Rhizobium meliloti, the root nodule symbiont of alfalfa. As a soil microbe, this organism is subjected to variable osmolarity and a number of other environmental conditions to which it must respond appropriately. Natural abundance 13C nuclear magnetic resonance spectroscopy was used to identify the osmolytes accumulated by osmotically stressed R. meliloti. The complement of osmolytes and their concentrations were found to depend on the level of osmotic stress, growth phase of the culture, carbon source, and the presence of osmolytes in the growth medium. The osmolytes accumulated by 22 different bacterial strains are presented and compared to those of R. meliloti 102F34. © 1994 Wiley‐Liss, Inc.
Structure and optics of the eye of the hawk‐wing conch, Strombus raninus (L.)
Authors: Seyer Jan‐Olof 
Published: June 2005

AbstractThe hawk‐wing conch, Strombus raninus, possesses extremely well developed camera‐type (simple) eyes. Light and electron microscopy were used to generate an accurate scale model of the eye, which was then used for predictions of its optical performance. The eye‐bulb measures approximately 1.6 × 1.9 mm and features a spherical lens, a large vitreous body, and a retina. The lens has a diameter of 950 μm and its centre consists of a seemingly homogeneous core with an approximate radius of 215 μm. The image produced by the lens is apparently aberration‐free and has a short focal length (950 μm). The ratio of the focal length to lens radius is approximately 2, and thus lower than the “Matthiessen ratio” of 2.5 frequently found in aplantic lenses of many marine animals. The crisp images produced by the lens imply the presence of a refractive index gradient despite an apparently homogeneous core. In the central retina, the inter‐receptor angle is 0.47° and the rhabdom diameter is 7.8 μm (5.7 times wider than the diffraction blur circle), indicating a retinal array coarser than that necessary to sample all the information contained in the image. The large aperture (850 μm) means that rays have the opportunity of striking the retina with incident angles of up to 41°, possibly degrading resolution further due to spread of light between rhabdoms (which lack shielding). Different aspects of the eye structure are discussed. © 1994 Wiley‐Liss, Inc.
Development ofGyrinophilus porphyriticus: Identification of the ancestral developmental pattern in the salamander family plethodontidae
Authors: Collazo Andres , Marks Sharyn B. 
Published: June 2005

AbstractWe describe the development, from fertilization to hatching, of the salamanderGyrinophilus porphyriticus(family Plethodontidae; tribe Hemidactyliini).G. porphyriticushas a relatively large clutch size (n = 87 eggs in the clutch examined) and egg diameter (mean = 4.0 mm, S.D. = 0.12, n = 4, range = 3.9–4.1) for a plethodontid. Early cleavage is asymmetrical and asynchronous. Gastrulation and neurulation are typical of that described for other species of plethodontids, particularly those with large, heavily yolked eggs. We present a normal table of development from tailbud to hatching divided into nine stages. Development of somites, pigmentation pattern, gills, tail fins, eyes, and limb buds is described. We use data from outgroup taxa, such as non‐plethodontid salamanders and frogs, to polarize nine characters chosen to define the ancestral developmental pattern of plethodontids: (1) developmental mode (direct or larval), (2) timing of oviposition, (3) clutch size, (4) percentage of egg volume contributing to embryonic structures, (5) timing of appearance of the front limb buds relative to the hind limb buds, (6) extent of gill branching, (7) presence or absence of tail fins, (8) external eye morphology, and (9) the presence or absence of lateral‐line organs. Comparisons ofG. porphyriticusto nine other plethodontid species allow us to hypothesize probable evolutionary transformations for these characters.G. porphyriticushas the ancestral condition for all nine characters. The three species ofDesmognathuswith aquatic larvae are derived for two or three of the nine characters. They each have (1) a clutch size of less than 50 eggs, (2) a relatively low percentage of egg volume contributing to embryonic structures, and/or (3) nearly simultaneous appearance of the front and hind limb buds. Finally, we explore the evolutionary implications of retaining the ancestral developmental pattern in the plethodontid tribe Hemidactyliini and salamanders in general. We propose that the retention of the ancestral developmental pattern has permitted the evolution of a specific type of paedomorphosis, larval paedomorphosis, that correlates with a cave‐dwelling existence. © 1994 Wiley‐Liss, Inc.
Freeze tolerance adaptations in the centipede, Lithobius forficatus
Authors: Tursman Donald , Duman John G. , Knight Charles A. 
Published: June 2005

AbstractStudies were conducted to investigate the adaptations of the wood centipede, Lithobius forficatus, to winter conditions. During winter centipedes were freeze tolerant. However, inoculative freezing initiated from external ice was required for survival of freezing. Because the lower lethal temperature (after 24 hr exposure) was only −6°C, it appears that the insulation provided by the overwintering microhabitat under large logs is important for survival. Freezing proved lethal to summer animals.Inoculative freezing points of live specimens remained steady at approximately −1°C throughout the year, as did the melting points of hemolymph. Although the supercooling points of the hemolymph stayed roughly constant at −7 to −9°C, those of live animals rose in winter and decreased in summer, suggesting the presence of nonhemolymph ice nucleators in winter. However, inoculative freezing was still essential for freeze tolerance. Centipedes did not accumulate carbohydrates or polyols in winter.Winter hemolymph showed marked recrystallization inhibition activity, indicating the presence of thermal hysteresis proteins, but summer hemolymph did not. However, only occasional individuals had measurable thermal hysteresis activity in winter, indicating that the hemolymph concentration of thermal hysteresis proteins is low. © 1994 Wiley‐Liss, Inc.
Plasma ketone, glucose, lactate, and alanine levels in the vascular supply to and from the brain of the spiny dogfish shark (Squalus acanthias)
Authors: De Roos Roger 
Published: June 2005

AbstractPaired, serial blood samples were collected for a minimum of 6 hr to a maximum of 15 days from cannulae chronically placed in the internal carotid artery (A) to the brain and the anterior cardinal sinus (V) from the brain of the spiny dogfish shark (Squalus acanthias). Previously fed animals were fasted for either 3 to 8 days (short‐fasted) or 20 to 29 days (long‐fasted) before the surgery to implant the cannulae and during the subsequent sampling periods. Plasma β‐hydroxybutyrate, acetoacetate, glucose, lactate, and alanine levels were measured by standard enzymatic procedures. The internal carotid artery plasma β‐hydroxybutyrate and acetoacetate levels were in the approximate ratio of 4 to 6:1, were greater in the long‐fasted than in the short‐fasted animals, and both ketones increased throughout the observation periods. In contrast, plasma lactate and alanine levels declined by postoperative day 2 to levels that, like glucose, remained relatively stable and were characteristic of the individual animal. The A‐V metabolite differences between the short‐ and long‐fasted animals were not significantly different and the data from the two groups of animals were combined for purpose of analysis. β‐Hydroxybutyrate was extracted from the plasma by the brain during both the surgery and recovery period (⩽ 2 days) and the “normal” under the observational conditions period (> 2 days). The small negative A‐V differences in acetoacetate during both periods, and in glucose during the > 2 day period, were not statistically significant. There were no evident A‐V differences in plasma alanine. Lactate was released by the brain during both the ⩽ 2 days and > 2 day periods. The uptake of β‐hydroxybutyrate and the release of lactate indicate that the spiny dogfish brain used both β‐hydroxybutyrate and glucose during the observation periods. The data suggest that the plasma was the immediate source of β‐hydroxybutyrate, but, as proposed by previous authors, the proximate glucose source may have been provided by the mobilization of endogenous brain glycogen stores. © 1994 Wiley‐Liss, Inc.