bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phosphatase active antigens in sea urchin eggs and embryos. I. Substrate specificity, pH‐optima and inhibitors
Authors: Westin Monica 
Published: June 2005

AbstractPhosphatase activity in sea urchin embryonic antigens was investigated by histochemical staining of immunoprecipitates separated by two‐dimensional (crossed) immunoelectrophoresis. Unfertilized eggs were homogenized in a hypotonic medium which solubilized cytoplasmic antigens. Antigens integrated in membranes or enclosed in particles were solubilized by detergent treatment of the residual pellet. Two different phosphatase activities were discerned in the unfertilized eggs, nucleoside diphosphatase (EC 3.6.1.6.) and acid phosphatase (EC 3.1.3.2.). Nucleoside diphosphatase activity was obtained in both the water soluble and detergent extracted protein fractions. This activity was confined to one antigen. Acid phosphatase activity on the other hand was almost exclusively obtained in the detergent extracted fraction and about ten distinct antigens displayed this activity. The nucleoside diphosphatase active antigen preferentially hydrolyzed purine nucleoside diphosphates and to a lesser degree triphosphates of these nucleosides. The acid phosphatase active antigens had a broader substrate specificity and hydrolyzed equally well β‐glycerophosphate and nucleotides. Both activities were essentially inactive at neutral or alkaline pH values. The activities were inhibited by p‐choloromercuribenzoate and accordingly stimulated by cysteine. Tartrate and sodium fluoride, however, inhibited the acid phosphatase activity while nucleoside diphosphatase activity was either stimulated or not affected at all by these agents.
Conjugation in Oxytricha bifaria: Cell interaction
Authors: Ricci Nicola , Esposito Fulvio , Nobili Renzo 
Published: June 2005

AbstractAs a model of cell interaction, the mating process of Oxytricha bifaria has been investigated. Mating involves several distinct and stereotyped stages, each lasting a determined time, and ending with the formation of firmly united pairs. A “waiting period” intervenes between the mixture of complementary mating types and the onset of cell interaction. A proper starvation shortens the waiting period (25 min vs 120 min). Treatment of properly starved cells with heterologous cell‐free fluid further reduces the waiting period. Certain enzyme treatments (pronase, trypsin and lipase) dramatically increase the waiting period in both washed enzymetreated cells and in unwashed cells. Trypsin inhibits the first two stages of the mating process, while lipase inhibits membrane fusion between mates.
Irradiation inhibits the regeneration of aneurogenic limbs
Authors: Wallace H. , Maden M. 
Published: June 2005

AbstractThe developing arms of axolotl larvae from the 2‐digit stage onward and the aneurogenic arms of surgically denervated larvae maintained in parabiosis are able to regenerate after amputation. Such regeneration is uniformly inhibited by local irradiation of the arm, whether innervated or not. This demonstration refutes a recent hypothesis that X‐rays interfere with a special activity of nerves required for regeneration, and supports the earlier concept that X‐rays act directly on those cells which must proliferate to form the regenerated tissues.
Phenoloxidase in the periostracum of the marine bivalve Modiolus demissus dillwyn
Authors: Waite J. Herbert , Wilbur Karl M. 
Published: June 2005

AbstractPhenoloxidase was extracted from Modiolus demissus mantles and periostraca with the detergent sodium dodecyl sulfate. Partial purification of the periostracal enzyme was achieved by gel filtration and polyacrylamide gel electrophoresis. The enzyme, present in the mantle in latent or proenzyme form, can be chymotryptically activated. Molecular weights of the proenzyme and active enzyme as determined by SDS gel electrophoresis were 80,000 and 70,000 daltons, respectively. A considerable portion of phenoloxidase activity in the periostracum is associated with a large macromolecule that cannot be reduced into smaller subunits, suggesting enzyme covalently immobilized by quinones. Optimal pH of 8.0–8.5 was found for the active enzyme (MW 70,000). Activity was diminished by adding copper chelators or by reducing disulfide bonds. In the former case, activity was restored by titrating the inhibitor with divalent copper. A hydrophobic active site on the enzyme is suggested by low Km and high reaction velocities for substrates with high partition coefficients in 2‐octanol:water such as 4‐methylcatechol and 4‐butylcatechol.
The effects of temperature and thermal acclimation upon the osmotic properties and nonelectrolyte permeability of liver and gill mitochondria from rainbow trout (Salmo gairdneri)
Authors: Hazel Jeffrey R. , Schuster Victor L. 
Published: June 2005

AbstractThermal acclimation of rainbow trout (Salmo gairdneri) taken from 20°C to 7°C resulted in adaptation of mitochondrial function, as evidenced by increases in the specific activities of NADH‐ and succinate‐cytochrome c reductase of 1.93‐ and 2.7‐fold respectively. Mitochondria from both gill and liver obeyed the Boyle‐van't Hoff relationship in the range from 400 to 60 mosM. Thermal acclimation had no effect on the osmotic properties of liver mitochondria, whereas gill mitochondria from cold‐acclimated trout were more sensitive to osmotic swelling than mitochondria from warm‐acclimated individuals. The non‐electrolyte permeability of liver mitochondria was assessed by optically monitoring mitochondrial swelling rates in isosmotic solutions of urea, glycerol, mannitol and glucose. Two parameters of mitochondrial swelling were determined: (a) initial swelling rates, d(1/A)dt, and (b) swelling constants, ks, derived from the time required to swell a fixed volume. Regardless of the assay temperature or the permeant employed, liver mitochondria from cold‐acclimated trout exhibited greater initial swelling rates than mitochondria from warm‐acclimated trout, indicating properties of temperature‐compensated permeability. The apparent ranking of nonelectrolyte permeabilities was urea > glycerol > mannitol > glucose. ks values for urea and glycerol from cold‐acclimated trout were greater than values typical of warm‐acclimated populations; however ks values for glucose and mannitol were not influenced by thermal acclimation. Regardless of the permeant considered, activation energies for ks values were 3‐ to 5‐fold greater than those for initial swelling rates. The time course of mitochondrial swelling consists of two components, an initial rapid swelling phase characterized by a half life of 3–12 seconds, and a slower swelling phase characterized by a half life of 1–6 minutes. Initial swelling rates, which approximate the rapid swelling component, are considered to be the least ambiguous index of permeability, whereas ks values are more complex and strongly influenced by the slower swelling component.
Intercalary and supernumerary regeneration in regenerating and mature limbs of Notophthalmus viridescens
Authors: Bryant Susan V. , Iten Laurie E. 
Published: June 2005

AbstractWe describe the ability of advanced limb regenerates and mature limbs of Notophthalmus viridescens to undergo intercalary and supernumerary regeneration following grafting operations to confront normally nonadjacent cells. Although both of these types of regeneration are known to be exhibited by regenerating limbs up to the stage of early digits, this is the first investigation of these abilities in mature limbs of Notophthalmus viridescens using similar grafting procedures. The autopodia of mature limbs, or regenerates at the stage of late digits or older from a distal level of amputation (distal third of forearm), were transplanted to other limb sites so as to oppose either anterior and posterior, or dorsal and ventral positions of stump and transplant. Following transplantation of either the regenerate or the mature autopodium, supernumerary limbs were sometimes formed, and their handedness, position and orientation were, in those cases in which they could be accurately determined, similar to what has been found previously in experiments on younger regenerates. Unlike the results of the experiments on regenerating limbs, when mature autopodia were grafted ipsilaterally with 180° rotation, the handedness of the supernumerary limbs could seldom be determined, and their location appeared to be random. An enhancement of the incidence of supernumerary limb formation in mature limb grafts was noted when the grafts were made so as to oppose normally nonadjacent proximal‐distal as well as circumferential positions.When advanced regenerates were grafted ipsilaterally and without rotation to a more proximal limb level (mid upper arm), good intercalary regeneration of the distal portion of the humerus as well as the radius and/or ulna occurred in most, but not all cases. When similarly grafted mature autopodia were examined, it was found that none of the limbs formed a complete intercalary regenerate, but the majority formed partial intercalary regenerates by completing the humerus. When mature autopodia were grafted so as to oppose normally non‐adjacent circumferential as well as proximal‐distal positions, then the intercalary regenerate was more complete and frequently included a regenerated radius and/or ulna, normally in conjunction with one or more supernumerary limbs. The similarities between these findings and our earlier ones on intercalary and supernumerary regeneration in regenerating newt limbs are discussed in terms of a recently developed model for pattern regulation in epimorphic fields.
Patterns of heart and scaphognathite activity in the crab Cancer magister
Authors: McDonald D. G. , McMahon B. R. , Wood C. M. 
Published: June 2005

AbstractThe respiratory system of the crab Cancer magister has been investigated with long‐term measurements of the activity in the heart and scaphognathites of unrestrained animals settled on a natural, sandy substrate. Although crabs generally remained motionless in the experimental apparatus, except while in the dark, they initially exhibited a high degree of respiratory activity; the rates of forward pumping by the scaphognathites exceeded 90/minute, reversal incidence was less than five reversals/10 minute and heart rate was constant. Subsequently both the heart rate and the forward pumping rates of the scaphognathites declined, incidence of reversals increased and spontaneous pauses by the heart and scaphognathites began to occur. Eventually one scaphognathite ceased pumping for prolonged periods. Possible roles for reversals, pauses and unilateral pumping are discussed.
Photoperiodic and thermoperiodic interaction affecting fat stores and reproductive indexes in the male green anole, Anolis carolinensis
Authors: Noeske Teresa A. , Meier Albert H. 
Published: June 2005

AbstractDaily fluctuations in warm (30°C) and cold (20°C) temperatures have different effects on fat stores and gonad weights of male Anolis carolinensis than constant warm or cold temperatures; and the effects vary depending on the phase relations of the daily thermoperiod with a daily photoperiod. In addition there is a seasonal change in the thermoperiod‐photoperiod interaction. For example an 8‐hour interval of warm temperature beginning eight hours after the onset of a 6‐hour daily photoperiod during July is more stimulatory for testicular weights than similar intervals of warm temperature beginning at 0 or 16 hours after the onset of light, but it is less stimulatory in October. The results suggest that the interaction of thermoperiodic and photoperiodic cycles may have important roles in regulating the annual cycles of reproduction and lipid metabolism.
Regulation of the bacterial microflora of the vagina in cyclic female rats
Authors: Koiter T. R. , Hazenberg M. P. , Van der Schoot P. 
Published: June 2005

AbstractThe bacterial microflora was examined in the vagina of cyclic female rats kept under normal laboratory conditions. Large variations occurred during the cycle with high numbers of bacteria (105‐108 per vagina) during proestrus and estrus and low numbers (101‐104 per vagina) during the diestrus period. Histological analysis of in situ vaginal tissue and transplanted vaginal tissue revealed an association of high bacterial numbers with the presence of large amounts of cellular debris in the vaginal lumen during the period of epithelial keratinization. Absence of phagocytosis in leucocytes at metestrus suggested that leucocytes did not play an active role in reduction of bacterial numbers between estrus and metestrus. Accurate measurement of the pH in the vaginal lumen failed to reveal differences which could explain the reduction in bacterial numbers between estrus and metestrus. The cyclic changes in the bacterial population–consisting of species which are normally present in the intestinal flora–seem to be controlled by cyclic changes in the amounts of cellular debris in the vaginal lumen.
Oxygen uptake by Nautilus pompilius
Authors: Redmond J. R. , Bourne G. B. , Johansen K. 
Published: June 2005

AbstractThe oxygen uptake of Nautilus pompilius at 17°C was 27 ml O2·kg−1·h−1 for calm species and 52 ml O2·kg−1·h−1 for active specimens. At 25°C the corresponding uptakes were 64 and 109 ml O2·kg−1·h−1. Oxygen con‐sumption dropped as the oxygen content of inhalant water dropped. Uptake ceased at about 20 mm Hg O2. Nautilus appears to have a lower oxygen demand and an oxygen delivery system less well developed than of that the modern cephalopods.
Metabolic and ultrastructural organization in Nautilus muscles
Authors: Hochachka P. W. , French C. J. , Meredith J. 
Published: June 2005

AbstractArginine phosphate is the phosphagen in Nautilus muscles. During “burst” work, arginine concentrations rise to high levels in muscles (up to 70 μm/gm), but arginine is not released into the blood circulation in significant amounts. Instead, arginine either is reconverted to arginine phosphate in situ or it condenses with pyruvate to form octopine, a reaction that oxidizes NADH and removes a highly basic metabolite from the cell. Octopine, formed in muscles, may have two possible fates: either it is released into the blood and is reconverted to arginine plus pyruvate elsewhere (e.g., in liver and gills), or it is re‐metabolized in situ. Of the two, the latter seems more important in Nautilus. Muscles of Nautilus also seem to have a vigorous amino acid metabolism, the details of which are not yet well understood. It is evident, however, that substantial pH gradients can develop between the arterial and venous blood apparently as a result of vigorous deamination and amination reactions.
Some aspects of hemodynamics in Nautilus pompilius
Authors: Bourne George B. , Redmond James R. , Johansen Kjell 
Published: June 2005

AbstractBlood pressure recordings from the ventricle, dorsal aorta, dorsal hemocoel, vena cava, afferent and efferent branchial veins show that the Nautilus pompilius cardiovascular system possesses similar functional characteristics to those of the modern coleoid cephalopods. In free swimming animals at 17° C ± 1° the contraction rate of the systemic ventricle varied between 5 and 18 beats per minute. Systolic blood pressure averaged 35 cm H2O while diastolic pressure averaged 16 cm H2O in the dorsal aorta. Peak and low pressures in the afferent branchial vein were 9 cm H2O and 1 cm H2O respectively while the mean pressure in the efferent branchial vein was 2 cm H2O and in the vena cava it was 2.2 cm H2O.The contour of the flow pulse recorded from the dorsal aorta indicated a backflow marking the point of aortic valve closure.Hemodynamics of the Nautilus pompilius cardiovascular system are discussed.
Adaptation of the tree frog, Hyla cinerea, to colored backgrounds, and the rôle of the three chromatophore types
Authors: Nielsen Hans Ingolf , Dyck Jan 
Published: June 2005

AbstractMeasurements have been made of the spectral reflectance of the dorsal skin of living tree frogs, Hyla cinerea.The colors assumed by the frogs when placed on backgounds of different col‐ors varied with respect to both dominant wavelength (565–580 nm), purity (42–58%) and lightness (2–19%).A certain adaptation to the lightness of the background took place, whereas adaptation to hue and purity seems almost negligible.On the basis of reflection measurements of single chromatophores and chro‐matophore associationa, a model is proposed for the color generation in the chromatophores, assuming an absorption of short‐wave light in the xantho‐phores, a reflection of short‐and medium‐wave light (blue, green) from the iridophores, and almost total absorption of all light in the melanophores, and a uniform, but subtotal, reflection of light of all wavelenghts from the connective tissue.It is suggested that the states of dispersion of the three types of chro‐matophores may be related to simple parameters which can be calculated from the reflectance spectra. Using these parameters it was found that mela‐nophores, xanthophores and iridophores all play an active part in the color change, and an explanation is presented on how the observed frog colors are generated by means of changes in the chromatophores.The three types of chromatophores probably are able to react independently of each other, thus indicating that the unihumoral theory fails to explain the color changes in Hyla cinerea.
Purification and properties of glutamate dehydrogenase from the mantle muscle of the squid, Loligo pealeii. Role of the enzyme in energy production from amino acids
Authors: Storey Kenneth B. , Fields Jeremy H. A. , Hochachka Peter W. 
Published: June 2005

Abstract
The activity of glutamate dehydrogenase was measured in the tissues of the squid, Loligo pealeii. The enzyme occurs in high activity in digestive pouch, systemic heart, and all muscle tissues.
Glutamate dehydrogenase from mantle muscle is located intra‐mitochondrially, has a molecular weight of 310,000, and is electrophoretically similar to the enzyme, from all other squid tissues.
The enzyme from mantle muscle was purified 40‐fold by elution from DEAE‐cellulose and used for kinetic studies. The enzyme is NAD+‐specific, activated by ADP, AMP, and leucine, and inhibited by GTP, GDP, ATP, and reaction products (in particular NADH).
Squid glutamate dehydrogenase shows an almost absolute dependence on ADP. The purified enzyme is activated over 100‐fold by saturating concentrations of ADP (K)a = 0.75 mM). The pH optima are also altered significantly by ADP.
The enzyme appears to be kinetically adapted to favour glutamate oxidation in comparison to glutamate dehydrogenase from other sources. The evidence indicates that the primary role of glutamate dehydrogenase in squid mantle muscle is in regulating the catabolism of amino acids for energy production.
Electrophysiological responses of Heteronereis stimulated with sex pheromones (Annelida polychaeta)
Authors: Boilly‐Marer Yolande , Lassalle Bernard 
Published: June 2005

AbstractChemical stimulations by sex pheromones have been electro‐physiologically recorded on Heteronereis brain. The presence of the transformed parapodial cirri is necessary to the appearance of the intense and prolonged electrical activity of the brain.
Estrogen localization in the brain of the lizard, Anolis carolinensis
Authors: Martinez‐Vargas M. C. , Keefer D. A. , Stumpf W. E. 
Published: June 2005

AbstractEstrogen induces reproductive behavior in lizards by acting on specific areas of the brain. Neural areas that selectively concentrate radioactivity after 3H‐estradiol administration were mapped using thawmount autoradiography. Major accumulations of hormone‐concentrating cells occur in the medial preoptic area, basal hypothalamus, amygdala (n. ventromedialis telencephali) and in and around the torus semicircularis. Numerous smaller accumulations are also described and the topographical distribution is compared with that of avian and mammalian species.
Oocyte maturation without follicular epithelium alters egg shape in a dipteran insect
Authors: Went Dirk F. 
Published: June 2005

AbstractOocytes of the parthenogenetic gall midge Heteropeza pygmaea assume an elongate shape when they mature inside the follicular epithelium. However, when the oocyte‐nurse chamber complexes grow without the regular follicular layer, they form spherical eggs. Such eggs may develop as far as the blastoderm stage. These findings indicate that the follicular epithelium is responsible for the shape of the egg but is not required for oocyte maturation and for initial steps in embryonic development.
Splenic plaque‐forming cells (PFC) and stem cells (CFU‐s) during acute phenylhydrazine‐induced enhanced erythropoiesis
Authors: Kozlov V. A. , Zhuravkin I. N. , Coleman R. M. , Rencricca N. J. 
Published: June 2005

AbstractThe erythroid status and levels of splenic plaque‐forming cells (PFC) to sheep red blood cells (SRBC) were monitored in mice subsequent to acute phenylhydrazine (PHZ)‐induced hemolytic anemia. From ferrokinetic measurements, we noted a shift in erythropoiesis from bone marrow to spleen. The levels of splenic PFC were significantly depressed following PHZ‐induced erythroid differentiation. Although this immune depression may reflect competition at the stem cell levels, whereby pluripotent stem cells (CFU‐s) are preferentially differentiated into the erythroid line at the expense of lymphopoietic pathways, other possibilities cannot be excluded. In this regard, we have shown that loading of the mononuclear phagocyte system (MPS) by PHZ‐damaged erythrocytes effected profound depressions in splenic PFC numbers. Lastly, in addition to the well‐documented increases in CFU‐s migration from marrow to spleen during enhanced erythropoiesis, we noted increased migration of B lymphocytes (as assessed by PFC) in marrow‐shielded lethally‐irradiated mice given PHZ. We also provide data which show that PHZ‐damaged RBC evoke increased migration of CFU‐s in normal mice, indicating a possible involvement of the MPS in stem cell migration.
Renal excretion of urea in the salamander, Ambystoma tigrinum
Authors: Stiffler Daniel F. , Hawk C. Terrance , Fowler Beth C. 
Published: June 2005

AbstractRenal excretion of urea was assessed in adult and larval Ambystoma tigrinum by comparing simultaneous clearances of urea and inulin. The mean adult urea clearance ratio (Cu/CIn) was 0.70 ± 0.08 indicating net urea absorption. Larvae yielded a mean CU/CIn) of 0.92 ± 0.04. Individual larvae were quite variable however as approximately 30% displayed CU/CIn>1. There was a significant negative correlation between CU/CIn and fractional water reabsorption. Comparisons of larval kidney urea concentration (KU) and plasma urea concentration (PU) revealed a mean KU/PU of 1.43 ± 0.15. Treatment with 2,4‐dinitrophenol decreased larval CU/CIn to 0.80 ± 0.05 and KU/PU to 0.91 ± 0.08. Phloridzin also decreased CU/CIn (0.67 ± 0.06) however para‐aminohippuric acid had no effect. Hypophysectomy combined with cautery of the pituitary stalk resulted in CU/CIn of 1.71 ± 0.33 as compared to 0.84 ± 0.08 in shams. These results are consistent with the possibility of net urea secretion at some point in the A. tigrinum nephron, followed by passive reabsorption in the distal segments under the influence of antidiuretic hormone. Key words: DNP, hypophysectomy, nephrostome, PAH, phloridzin, urea secretion.
Exchange of skin grafts among monozygotic quadruplets in armadillos
Authors: Billingham Rupert E. , Neaves William B. 
Published: June 2005

AbstractSkin grafting experiments, with long‐term follow‐ups, on three litters of armadillo quadruplets born in our laboratory have confirmed the familiar rule that grafts exchanged between monozygotic littermates are not rejected as a consequence of alloimmune reactions. A possible explanation of the striking discrepancy between the present findings and those of a previous study is uncertainty about the relationships of the previous animals, which were obtained from a commercial dealer at 10 days of age.