bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sperm nuclei entering parthenogenetically activated mouse oocytes before the first mitosis transform into pronuclei an ultrastructural study
Authors: Maleszewski Marek 
Published: February 2005

AbstractBackground: This report is an extension of previous observations (Maleszewski 1992. Mol. Reprod. Dev., 33:215–221) on the behavior of mouse sperm nuclei incorporated into parthenogenetically activated mouse oocytes prior to the first cleavage division and undergoing transformation during mitosis.Method: Artificially activated mouse oocytes were inseminated in vitro and an ultrastructural analysis was performed of sperm‐derived nuclei present in two parthenogenetic two‐cell embryos.Results: Both chromatin and nuclear envelope of sperm derived‐nuclei are structurally identical with those of oocyte‐derived nuclei and of the nuclei of blastomeres of normal two‐cell embryos.Conclusions: Cytoplasm of the parthenogenote during the first mitotic division has the ability to transform sperm nucleus into a male pronucleus just like the cytoplasm of a metaphase II oocyte. © 1995 Wiley‐Liss, Inc.
Effect of bacoside A on membrane‐bound ATPases in the brain of rats exposed to cigarette smoke
Authors: Anbarasi K. , Vani G. , Balakrishna K. , Devi C. S. Shyamala 
Published: February 2005

AbstractMembrane‐bound enzymes play a vital role in neuronal function through maintenance of membrane potential and impulse propagation. We have evaluated the harmful effects of chronic cigarette smoking on membrane‐bound ATPases and the protective effect of Bacoside A in rat brain. Adult male albino rats were exposed to cigarette smoke for a period of 12 weeks and simultaneously administered with Bacoside A (the active principle isolated from Bacopa monniera) at a dosage of 10 mg/kg b.w/day, p.o. The levels of lipid peroxides as marker for evaluating the extent of membrane damage, the activities of Na+/K+‐ATPase, Ca2+‐ATPase and Mg2+‐ATPase, and associated cations sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+) were investigated in the brain. Neuronal membrane damage was evident from the elevated levels of lipid peroxides and decreased activities of membrane‐bound enzymes. Disturbances in the electrolyte balance with accumulation of Na+ and Ca2+ and depletion of K+and Mg2+ were also observed. Administration of Bacoside A inhibited lipid peroxidation, improved the activities of ATPases, and maintained the ionic equilibrium. The results of our study indicate that Bacoside A protects the brain from cigarette smoking induced membrane damage. © 2005 Wiley Periodicals, Inc. J Biochem Mol Toxicol 19:59–65, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20050
Visual responses in crayfish. III. Further studies on transmission through the brain
Authors: Camougis George , Kasprzak Hedwig 
Published: February 2005

AbstractResponses to illumination of the eyes of the crayfish were studied by gross recording from one of the circumesophageal connectives. Two‐thirds of the spontaneous activity at this level of the CNS consists of ascending activity, which is eliminated by cutting a connective posterior to the recording electrode. An average of about eight fibers in a connective responded to 1 sec illumination of the homolateral eye. The fibers were of four types: pure‐on units, on‐sustained units, on‐and‐off units and pure‐off units. The average latency was 74 msec for the on‐response and 26 msec for the off‐response. The latency of responses to 10 μsec flashes of increasing intensity shortened from 72 to 52 msec. This was demonstrated to be mainly a peripheral effect since ERG latency showed a parallel reduction while the ERG‐connective response interval remained more nearly constant at 40–50 msec. ERG amplitude, frequency, and usually the duration of the connective spike discharge increased at greater stimulus intensities, yet the average number of responding fibers was greatest at intermediate intensities. The results indicate minimal processing of response patterns by the brain.
The effects of modified ringer's solutions on the membrane potentials of innervated and denervated frog sartorius muscle fibers
Authors: Levine Leonard 
Published: February 2005

AbstractComparison has been made between innervated and chronically denervated frog sartorius muscle fibers for resting potentials and a number of features of the action potential. Muscles were obtained from force‐fed frogs maintained at room temperature for periods up to one year, and were studied with intracellular microelectrodes. Denervated muscles increased in sensitivity to acetylcholine by 100–400‐fold. Studies were made in normal Ringer's solution, and in media in which concentrations of K+, Na+, Ca++, and Cl− were altered. The only significant differences noted between the denervated and the innervated fibers were a reduction in the maximum rate of fall of the action potential (ca. 20%) and an increase in the fall time of the active membrane potential (ca. 25%). These differences were present in normal Ringer's solution and remained when the bathing medium was modified. The resting membrane potential of denervated and innervated muscles varied with log [K+]o in exactly the same manner, and followed the theoretical relation proposed by Hodgkin (Proc. Roy. Soc., B, 148: 1–37, ′58), with the term representing the ratio of the sodium to potassium permeabilities assigned a value of 0.01. The results suggest that (a) the resting sodium and potassium permeabilities are reduced proportionately after denervation, since it is known that denervated frog muscle has a smaller potassium permeability, and (b) the mechanism controlling the increase in potassium conductance during the action potential is less available after denervation. Data indicate that the system controlling the sodium permeability is capable of activation to the same extent as in innervated muscles. Muslces which had been allowed to reinnervate did not show the differences presented by the denervated muscles. Innervated and denervated muscles did not show any significant changes in maximum rates of rise or fall of the action potential, nor of the active membrane potential amplitude over a 30 mV range of resting membrane potentials, indicating that the sodium and potassium permeability systems are fully available in frog muscle at membrane potentials larger than −80 mV.
Separation of rabbit red cells by density in a bovine serum albumin gradient and correlation of red cell density with cell age after in vivo labeling with 59Fe
Authors: Bishop Charles , Prentice Theodore C. 
Published: February 2005

AbstractRabbit red cells are separated by centrifuging them for one hour at 33,000 G in density gradient tubes of bovine serum albumin. The separation represented an equilibrium situation since rebanding experiments showed that the cells from a layer would again seek that density layer when recentrifuged in a new gradient tube. When rabbits were injected with 59Fe, the radioactive red cells at one day were nearly all light, but these labeled cells moved into the more dense layers over the next few days. This not only shows that the separation by density is discriminating but that some red cells became dense very quickly. Bearing in mind the problems of interpreting radioactive iron data because of the possibility of reutilization, it is tentatively concluded that dense red cells are not necessarily senescent red cells since these dense cells appear to persist for the normal life span of the rabbit red cell.
The effect of serum albumin on the efflux of K42 from frog sartorius muscle
Authors: Armstrong William McD. , Knoebel Suzanne B. 
Published: February 2005

AbstractThe effect of serum albumin on the washout of K42 from isolated frog sartorius muscles, previously labeled in vitro with this isotope, has been investigated. Incorporation of 1% serum albumin in the washout fluid has been found to cause a significant reduction in the rate constant for K42 loss from the muscle fibers. A similar reduction in the rat constant for K42 efflux was observed when the medium, though not containing protein, was exhaustively dialyzed before use against a solution containing serum albumin. Addition of 10−6 M HgCl2 to “dialyzed” Ringer increased the rate of loss of K42 from the fibers. Effects similar to those obtained with serum albumin were observed when 10−4 M cysteine was incorporated in the washout fluid. 3‐mercapto‐propanol gave rise to transient reductions in the rate of K42 efflux, but, following prolonged exposure to this agent, the efflux rate was increased. 2′3‐dimercapto‐propanol (BAL) increased the rate of K42 loss from the fibers. It is suggested that this effect of serum albumin is due to its sequestering action on toxic substances (tentatively identified as heavy metals) normally present in trace amounts in Ringer's solutions.
RNA synthesis and cell division in cold‐synchronized cells of Tetrahymena pyriformis
Authors: Moner J. G. , Berger R. O. 
Published: February 2005

AbstractCells of Tetrahymena pyriformis have been cold‐synchronized using a repetitive cycle of six, two‐hour cold shocks (9.5°C) alternating with decreasing periods (60–30 minutes) at 28°C. This system gives a maximum division index of 70–80% occurring at 90 minutes from the end of the last synchronizing cold‐treatment (EC). Examination of the division sensitivity of these cells to actinomycin D applied continuously at ten‐minute intervals from EC reveals that division is essentially blocked until approximately 40 minutes past EC, after which a rapid decrease is sensitivity to the inhibitor occurs. Coinciding with this period of high sensitivity is the occurrence of a peak of C14 uridine incorporation at 40 minutes past EC. Inhibition of this peak is correlated with an inhibition of division, whereas strong inhibition of RNA synthesis beyond 60 minutes past EC has little effect on division activity. The similarity of these findings with those of the heat‐synchronized system is discussed with the suggestion that both heat‐ and cold‐synchronizing treatments result in the synchronous resynthesis of a division‐associated fraction of RNA.
The effect of hematoporphyrin and light on human platelets. II. Uptake of hematoporphyrin
Authors: Solomon Harvey M. , Zieve Philip D. , Krevans Julius R. 
Published: February 2005

AbstractA linear relationship was demonstrated between the reciprocals of the concentration of free hematoporphyrin and the moles of hematoporphyrin taken up by the platelet in the dark. radiated platelets took up more hematoporphyrin than did controls; this increase in uptake was accounted for by the movement of the dye across the damaged membrane of the cell. platelets irradiated at 4°c remained impermeable to hematoporphyrin until warmed to 37°c. during the initial three to four minutes of exposure to light at 37°c, there was no additional uptake of hematoporphyrin by platelets in comparison to controls. between six to ten minutes irradiation, the uptake of hematoporphyrin increased linearly with the log time of irradiation. thereafter, no further uptake occurred. a further increase in uptake of dye was demonstrated by both control and irradiated platelets at a reduced ph. this study enables a correlation to be made between the effects of hematoporphyrin on the platelet and the uptake of this agent by the platelet.
Respiratory activity of avian blood cells
Authors: Besch Emerson L. 
Published: February 2005

AbstractThe respiratory activity of avian blood cells was determined with samples of whole blood from individual male and female chickens. this oxygen consumption represents only that of the cells since no measurable activity was found in the plasma samples. the precision of determining respiratory activity was examined statistically and found to be approximately that obtained with a blood cell count but much less precise than the packed cell volume determination. the variability of cell count and mean corpuscular volume indicates that neither is a good means for expressing oxygen consumption – the most meaningful basis is oxygen consumption per milliliter of cells. the relationship between blood cell respiration and temperature is described.
Anti‐mitotic effects of colchicine and hydrostatic pressure; synergistic action on the cleaving eggs of Lytechinus variegatus
Authors: Marsland Douglas 
Published: February 2005

AbstractLow concentrations (below 0.00005 m) of colchicine and low intensities (below 2,800 psi) of pressure, applied separately to early prophase eggs (lytechinus variegatus) produced no measurable inhibition of the first cleavage division (at 20°c). in combination, however, these subliminal treatments produced marked inhibition. complete blockage, in fact, was observed: at 2,300 psi for eggs in 0.00004 m colchicine; at 2,500 psi for eggs in 0.00003 m; and at 2,800 psi for eggs in 0.00002 m solutions.The curves obtained by plotting percentage inhibition as a function of pressure for each of the colchicine concentrations specified above were approximately parallel to one another; but each decrement in the colchicine concentration shifted the curve about 300 psi higher along the (pressure) abscissa.In short, a distinct synergism was found in reference to the anti‐mitotic effects of colchicine and pressure. This result is quite opposite to that reported previously in regard to the actions of heavy water and high pressure.As to basic mechanism, the evidence indicates that both colchicine and pressure exert their effects by inhibiting polymerization of the subunits of a fibrous protein which constitutes an important structural component of the mitotic apparatus or by depolymerizing the mitotic protein, if it already has been formed at the time of treatment.
Movements of myelin sheath particles in a weak electric field
Authors: Wiener Henry , Wolman Moshe 
Published: February 2005

AbstractWhen a weak electric field is applied to longitudinal sections of myelinated nerve, myelin material migrates out of the tissue edges towards both poles. the materials migrating from the anodal and cathodal edges seem to be chemically similar but differ in physical properties. at the anodal edge the bimolecular lipid layers rearrange into spherical micelles forming an “oil in water” emulsion, and at the cathodal edge into micelles forming a “water in oil” emulsion. the latter is unstable in water and is rapidly transformed into an “oil in water” emulsion. these findings have physiological and structural implications for the study of biological membranes.
Effect of CO2 on the growth of a bleached Euglena
Authors: Tremmel R. D. , Levedahl B. H. 
Published: February 2005

AbstractThe addition of CO2 in gaseous form to the growth medium of Euglena gracilis var bacillaris (streptomycin bleached) results in a marked increase in the peak populations reached by the organism. when 20 mm succinate is used as the carbon source, the increase in peak population is proportional to the percentage CO2 enrichment of an air wash up to at least 10% CO2. when acetate is used as a carbon source for growth, some increase is seen in the peak population reached by euglena but the increase is not dependent upon the percentage enrichment of CO2 between 2 and 10% CO2. this extended growth is dependent up the presence of gaseous CO2; bicarbonate ion actually inhibiting growth. thiamin is not required for the CO2 effect, in fact no thiamin requirement can be demonstrated for this organism under the conditions of this experiment.
Ion and water shifts produced by ammonium chloride in high K and low K red cells
Authors: Salminen Simo , Manninen Vesa 
Published: February 2005

AbstractThe effect of ammonium chloride on the cellular Na+, K+ and water has been examined in human and horse (high K), cow (medium K) and cat (low K) red cells. It was found that high K red cells, especially those of the horse, gained water an Na+, whereas the net movement of K+ was negligible. There was a correlation between the increase of cellular Na+ concentration and of the packed red cell volume. In contrast, the packed cell volume of low K red cells increased slightly or not at all, and Na+ ions leaked out from the cells. The high K cells had a lower Cl− concentration and higher buffer capacity than the low K cells. The results obtained with the medium K (cow) cells usually lay between those of the other two cell types. In all the cases both the plasma and cell pH decreased resulting from the addition of ammonium chloride. The mechanism of movements of water and Na+ ions in high K cells remained unsolved, but the response of low K cells to ammonium chloride was near that of a cation exchange resin.
The effect of hematoporphyrin and light on human platelets. III. Release of potassium and acid phosphatase
Authors: Zieve Philip D. , Solomon Harvey M. 
Published: February 2005

AbstractHuman platelets, exposed to hematoporphyrin and light, were depleted of potassium and acid phosphatase. A linear relationship was demonstrated between the per cent depletion of potassium from irradiated platelets and the log dose of hematoporphyrin. The initial release of potassium and acid phosphatase from irradiated platelets was first order. Rate constants demonstrated that potassium was released five times faster than acid phosphatase. At 4°C, release of both potassium and acid phosphatase was the same as at 37°C. These results are compared to previous data on the release of serotonin from irradiated platelets.
Enzyme distribution in “naturally‐decapitated” bull spermatozoa: Acetylcholinesterase, adenylpyrophosphatase and adenosinetriphosphatase
Authors: Nelson Leonard 
Published: February 2005

AbstractNaturally‐decapitated spermatozoa were separated into motile flagella and head and immotile flagella by differential and density gradient centrifugation. In preparations microscopically free of cross‐contamination after repeated centrifugation, the heads appeared to be enzymatically inert, while there was virtually no change in the specific activity of the immotile flagella which had been subjected to as much manipulation as the heads. The non‐motile flagella had almost twice the acetylcholinesterase and about one‐third the apyrase activity of the motile flagella. The flagella appear to contain a structurally‐bound adenosinetriphosphatase which may be identical with the “spermosin” extracted from bull sperm.
Orthophosphate excretion as related to RNA metabolism in Tetrahymena
Authors: Cline Sylvia G. , Conner Robert L. 
Published: February 2005

AbstractLog phase cultures of Tetrahymena pyriformis W excrete orthophosphate, a purine, and a pyrimidine when suspended in a non‐nutrient buffered medium. Ribonucleic acid has been established as the primary source of these catabolic products. Thirty per cent of the total cellular RNA was degraded in three hours under the conditions of growth and suspension employed. The size of the phosphorus pools of these ciliates was determined during the period of RNA degradation; the internal acid‐soluble organic phosphate and the cellular orthophosphate pools remained constant for five hours at 20% and 5% of the total cell phosphorus respectively. The ultraviolet‐absorbing materials excreted with the orthophosphate were identified as hypoxanthine and uracil. A pentose, presumably ribose, was excreted in small quantities, but was not equivalent in amount to the orthophosphate and did not parallel the pattern of release of the anion. The excretion of orthophosphate, hypoxanthine, and uracil is correlated with the catabolism of RNA as it has been demonstrated in these cells.
Sodium transport inhibition by selective mitochondrial inhibitors in the urinary bladder of the toad
Authors: Hidalgo Cecilia , Canessa‐Fischer Mitzy 
Published: February 2005

AbstractThe effects of selective mitochondrial inhibitors on the short‐circuit current and oxygen consumption displayed by the isolated urinary bladder of the toad was studied.Three types of compounds were used: (a) electron transfer inhibitors, Amytal, Cyanide and Antimycin A; (b) energy transfer inhibitors Guanidine, Oligomycin and Rutamycin; and (c) uncoupling agents, Carbonyl cyanide m‐chlorophenylhydrazone and 2–4 dinitrophenol.The kinetics of inhibition of oxygen consumption indicated that the inhibitors tested were effectively reaching the mitochondria of the bladder cells.Different kinetics of inhibition of short‐circuit current were obtained with the various inhibitors tested.Uncouplers and electron transfer inhibitors rapidly blocked the short‐circuit current; energy transfer inhibitors only produced a slow and partial inhibition.A site of energy‐coupling, tentatively identified with the intermediate formed in the energy transfer reactions closest to the electron transfer chain, is proposed.
The response of the early chick embryo heart to anoxia
Authors: Roberts Carmel Montgomery 
Published: February 2005

AbstractIsolated 3‐ and 5‐day chick embryo hearts contain sufficient endogenous substrates to maintain their pulsatile activity for several hours under aerobic conditions, and even after five hours in substrate‐free medium the rates are 40 to 50% of the original rates. Carbohydrate appears to be an important component of the endogenous substrates since 1 mM 2‐deoxyglucose causes rapid failure of rate, and glycolysis appears to be a major energy pathway since the rate is depressed only about 50% by 2‐hour's exposure to 10 mM fluoroacetate. In nitrogen the hearts rapidly become asystolic in the absence of added substrate. Recovery of the rate occurs if oxygen is reintroduced within one hour, but longer periods of anoxia result in progressively less recovery, especially with the 3‐day hearts which appear to be particularly susceptible to irreversible damage. With 5.55 mM glucose as substrate there is little decrease in the original aerobic heart rate during five hours, and the hearts can tolerate total anoxia for five hours with rates only slightly less than the aerobic rates. The hypothesis of a preferential pentose phosphate pathway of glucose catabolism in the very young chick embryo heart is discussed, but no direct evidence in support of its existence is revealed in this study.
Tritiated‐histidine incorporation into Drosophila salivary chromosomes
Authors: Pettit Barbara J. , Rasch Robert W. 
Published: February 2005

AbstractAn autoradiographic study of H3‐histidine incorporation into nonhistone protein of explanted larval salivary gland chromosomes of D. virilis showed patterns of incorporation that were dependent upon the stage of larval development. The sequence of changes in the development of several puffs in a specific chromosomal region was followed using the appearance of pigment in the anterior spiracles as a means of larval staging. H3‐histidine incorporation into these puffs in prepupae occurred as the puffs were regressing in size and protein staining. Acid extraction of histone and nucleic acid failed to alter the character of the autographs; presumably a non‐histone protein is involved in the H3‐histidine incorporation. Other puff sites in the same prepupal chromosomes showed various patterns of isotopic amino acid incorporation indicating that the pattern reported for a specific region may not be true for all puff sites.