bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dedifferentiation and mitotic activity in amputated newt tails locally deprived of the spinal cord (Including a note on effects of amputation level on mitosis)
Authors: Donaldson Donald J. , Wilson Jack L. 
Published: June 2005

AbstractThe spinal cord of freshly amputated newt tails was displaced cranially by pushing several paraplast chips into the spinal canal with a glass needle. That part of the canal formerly occupied by the spinal cord was then packed with paraplast. Tails treated in this manner failed to regenerate, forming no more than a millimeter of new tissue with little or no cartilage and muscle. Dedifferentiation and early mitotic activity, however, was normal, indicating that the spinal cord exerts its effect on tail regeneration in the later stages. Amputation through the proximal region of a vertebra led to a significantly lower mitotic rate at four days than did amputation through the distal region, a situation contrary to the principle that during regeneration, elongation rate is generally faster from proximal than distal levels.
Experimental studies on a lethal gene (I) in the Mexican axolotl, Ambystoma mexicanum
Authors: Chung Hae‐Moon , Briggs Robert 
Published: June 2005

Abstract1. Gene l is a recessive lethal factor found in the white strain of axolotls. Animals heterozygous for the gene are phenotypically normal. When mated with each other they give offspring 25% of which exhibit the lethal effects of the gene. 2. The l/l homozygotes develop normally to an advanced embryonic stage (Harrison stage 40) before the effects of the gene are first manifested. They then come to display a characteristic combination of abnormalities, including a disproportionately small head, small and poorly developed eyes, abnormal poorly developed gills, undifferentiated limb buds, and reduced overall growth rate. They may feed briefly, but soon stop and invariably die within a few weeks of the time of hatching. 3. The action of gene l has been analyzed by parabiosing mutant and normal embryos, and by grafting various organ primordia reciprocally between mutant and normal embryos. Parabiosis to normal embryos fails to correct the abnormalities of the mutants, although their survival may be somewhat prolonged. Grafts of mutant organ primordia (eye, limb, gill, pronephros, gonad, head) also invariably fail to show improved development or to survive on normal hosts; normal organ primordia develop normally on mutant hosts so long as the mutant survives.These experiments indicate that gene l is a recessive autonomous cell lethal affecting all of the organ systems during late embryonic and early larval development.
Association of an ultraviolet irradiation sensitive cytoplasmic localization with the future dorsal side of the amphibian egg
Authors: Malacinski George M. , Benford Helen , Chung Hae‐Moon 
Published: June 2005

AbstractDrastic alterations in neural morphogenesis can be induced by ultraviolet irradiation of the amphibian egg. The target area of U.V. was determined either by direct irradiation of various regions of the egg or by comparing the area of the U.V. hit with the location of the dorsal lip. Axolotl eggs which displayed easily recognizable gray crescents were employed for the direct irradiation experiments and albino axolotl eggs were used for a comparison of the U.V. sensitivity of the animal and vegetal halves of the egg. Marked frog eggs were employed to determine the relationship between the sensitive area and the site of formation of the dorsal lip. It was concluded that the dorsal marginal zone of the fertilized, uncleaved egg was the most sensitive area of the egg.Ovarian homogenates provide a source of material for correcting, by microinjection, the effects of U.V.
Immunofluorescent localization of bovine acrosin
Authors: Garner Duane L. , Easton Marlys P. , Munson Mark E. , Doane Mark A. 
Published: June 2005

AbstractAcrosin, a trypsin‐like proteinase, was localized in the acrosome of methanol‐fixed bovine spermatozoa by the indirect immunofluorescent technique. Anti‐acrosin immunoglobulin was obtained from a rabbit immunized with highly purified bovine acrosin. The results of agarose‐gel immunodiffusion analyses indicated that although the antibody was specific for the acrosomal enzyme, it cross‐reacted with ovine acrosin.
Distance chemoreception‐triggered avoidance behavior of the limpets Acmaea (Collisella) limatula and Acmaea (Notoacmea) scutum to the predatory starfish pisaster ochraceus
Authors: Phillips David W. 
Published: June 2005

AbstractIn a flow of normal seawater, populations of the limpets Acmaea (Collisella) limatula and Acmaea (Notoacmea) scutum on a horizontal surface moved upstream (positive rheotaxis). In contrast, when the scent of the predatory starfish Pisaster ochraceus was present in the water current, populations moved downstream. On a vertical surface in a flow of normal (control) water, the populations moved strongly upward in the dark (negative geotaxis) and away from light (negative phototaxis). In the presence of Pisaster scent, negative geotaxis was increased both in the light and in the dark. Negative geotaxis appeared to be a stronger response than negative rheotaxis in the presence of Pisaster scent, since limpets on a vertical surface with starfish scent in a current directed downward from above still moved up. A sample of limpets tested repeatedly in the presence of Pisaster scent was found to contain individuals differing significantly in the number of positive responses evoked and the vertical distance traveled during a response. The adaptive significance of the responses is discussed.
Synthesis of soluble protein in oocytes of Xenopus laevis
Authors: Heidemann Steven R. , Townsend Janis , Tompkins Robert 
Published: June 2005

AbstractOocytes of five stages of development were isolated from ovaries of Xenopus laevis and allowed to take up radioactive amino acids. After six hours of labeling the amount of label incorporated into perchloric acid precipitable material from the soluble oocyte fraction and the specific activity of the label free pool was determined. From these figures an estimate of the rate of protein synthesis was calculated. Labeled soluble protein from each oocyte stage was analyzed by electrophoresis on SDS polyacrylamide gels. The gel was dried and autoradiographed to determine the qualitative pattern of soluble protein synthesis during various stages of oogenesis.Our results indicate that no significant differences exist in the rate of protein synthesis among any of the stages of oogenesis investigated. The qualitative pattern of soluble protein synthesized during the labeling period is similar among the oocyte stages. Moreover, this qualitative pattern of soluble protein synthesis is the same as the pattern of soluble protein accumulated up to that time during oogenesis.These results suggest a stable synthesis and accumulation of maternal protein products during Xenopus oogenesis, in marked contrast to the results that have been reported for RNA synthesis during oogenesis in Xenopus. Our results are discussed in terms of the present understanding of the process of maternal information accumulation.
Antibody‐mediated inhibition of immune responsiveness in baby chicks
Authors: Seto Frank 
Published: June 2005

AbstractAn experimental model for the analysis of antibody‐mediated regulation of specific immune responsiveness in chickens is described. Chick embryos and day‐old chicks were passively administered homologous serum with high anti‐mouse erythrocyte (MRBC) activity and then tested for immune responsiveness to MRBC several weeks later. Compared to the untreated controls, the hemagglutinin titers of experimental birds were obviously depressed for 2 to 3 weeks but near normal by the 4th week. The inhibitory property of homologous serum appeared directly related to the anti‐MRBC activity; serum samples collected on day 1 and 2 after immunization were ineffective and low in specific activity, whereas those collected after the 3rd day were progressively more inhibitory as the anti‐MRBC activity increased.
Initiation factor distribution in Xenopus laevis eggs
Authors: Garrison N. E. , Kaulenas M. S. 
Published: June 2005

AbstractThe distribution of activity similar to that of one of the initiation factors (1F2) was determined as a function of developmental stage in Xenopus laeviseggs and embryos. In vivo exposure of mature oocytes to hormone increases the total amount of detectable factor activity and facilitates the binding of 1F2‐like factor to ribosomes. The quality of factor bound is not correlated with polysome content.
A method for the chemical isolation of individual muscle fibers and its application to a study of the effect of denervation on the number of nuclei per muscle fiber
Authors: Cardasis Constance A. , Cooper George W. 
Published: June 2005

AbstractA method is described for isolating intact, individual skeletal muscle fibers from glutaraldehyde fixed muscle. This method was conceived to eliminate the many limitations of determining muscle nuclear numbers in histological cross section. Glutaraldehyde fixed fibers are isolated by dissection while in a solution of low concentration guanidine in a borate buffer at high pH. Electron microscopy demonstrates that single fibers, isolated in this manner, are free of their microvasculature and connective tissue. Their basal laminas and the structures within them, including their satellite cells, are preserved.This method is employed to determine whether changes in nuclear numbers occur within the basal lamina of individual muscle cells from 1 to 28 days following denervation of mouse gastrocnemius muscle. The total number of nuclei located within the basal lamina of individual muscle fibers (i.e. muscle and satellite cell nuclei) does not change after denervation. This rules out the possibility that additional nuclei are arising from an influx of cells outside the basal lamina or by mitotic division of nuclei within the basal lamina. However, the possibility of a change in the ratio of satellite cell nuclei, to muscle cell nuclei, is not eliminated.Other possible applications of this isolation method are discussed.
The influence of thyroxine and acclimation temperature on glycogen reserves of the frog Rana pipiens
Authors: Packard Gary C. , Randall James G. 
Published: June 2005

AbstractLeopard frogs were given daily injections of Na‐l‐thyroxine (2.0 μg/10 g body weight) for seven days, and control animals were given daily injections of the vehicle. During the period of treatment, half of the frogs were acclimated, in darkness and without food, at a constant temperature of 15°C, whereas the remainder of the animals were acclimated at 25°C. At the end of the seventh day, the frogs were killed by decapitation, and the glycogen concentration in samples of liver tissue and skeletal muscle was determined spectrophotometrically. Total hepatic glycogen of each frog subsequently was calculated from data on glycogen concentration and liver weight.Treatment of leopard frogs with thyroxine had no apparent effect on hepatic glycogen reserves of animals acclimated at 15°C, but there was a striking reduction in glycogen content of livers from hyperthyroid frogs held at 25°C. Mobilization of hepatic glycogen in thyroxine‐treated animals held at 25°C presumably was secondary to a general stimulation of oxidative metabolism. Treatment with thyroxine had no effect on the concentration of glycogen in skeletal muscle of leopard frogs held at either of the acclimation temperatures used in this study.
Ingestion of colloid solutions by filter‐feeding mosquito larvae: Relationship to viscosity
Authors: Dadd R. H. 
Published: June 2005

AbstractDuring ingestion tests of 1 to 3 hours duration with larval Culex pipiens, displacement of midgut contents was virtually nil for larvae filterfeeding in particle‐free water, whereas in various dilute colloid solutions displacement was rapid and comparable in rate to displacement in water containing particulate solids. For larvae in 0.01 to 0.1 % methylcellulose solutions or in 0.01 to 0.6% polyhall (polyacrylamide) solutions, having viscosities of approximately 1 to 1.5 or 1 to 3 centipoises, respectively, displacements increased with increasing concentrations from just detectable to maximal and remained maximally high for higher concentrations with viscosities up to 15 and 5 cp respectively. Progressively greater displacements were likewise observed with sucrose solutions of 4 to 20% and having viscosities of 1 to 1.5 cp, but at higher concentrations ingestion was poor because of severe osmotic damage to larvae. In 0.015% agar, which is about 10% more viscous than water, ingestion was virtually nil; but with a doubling of concentration to 0.03%, and with viscosity about 20% greater than for water, displacement was maximal. The correlation between increasing viscosity and increasing ingestion for methylcellulose, polyhall and sucrose implicates viscosity as a factor that may alter the mechanical properties of liquids so as to allow them to be ingested in bulk as readily as particulate solids. With agar, the viscosity difference between non‐ingested and maximally‐ingested concentrations was so small as to suggest that some other factor is involved in bringing about ingestibility, perhaps some property related to the molecular structure that at elevated concentrations of agar brings about the formation of gels.
Some additional observations relating to the mechanism of trypan blue induced teratogenesis
Authors: Hamburgh Max , Erlich Mark , Nathanson Ginger , Pesetsky Irwin 
Published: June 2005

AbstractThe mechanism and site of teratogenic action of trypan blue on mammalian embryos was reinvestigated. The experiments to be presented include (1) an analysis of the effect of trypan blue treatment on the morphology of the early mouse egg cylinder, (2) a demonstration of the effect of dye treatment on the enzyme acid phosphatase of yolk sac epithelium using histochemical procedures. Results obtained from these experiments indicate that trypan blue injected into mothers on day 7 of gestational age leads, within 12 to 24 hours after treatment, to dramatic abnormalities in 90–95% of egg cylinders examined. The frequency of gross malformations obtained by this treatment is considerably less when litters are examined at later stages of gestation. Acid phosphatase activity in yolk sac epithelium is depressed by the dye treatment, but there is no difference between enzymatically depressed yolk sacs of malformed embryos and yolk sacs surrounding normally appearing litter mates both obtained from trypan blue treated mothers. The hypothesis that trypan blue may exert its teratogenic effect by the direct exposure of egg cylinder stages to the dye, and that some of the egg cylinders affected may subsequently repair, is recommended for further testing.
The ontogeny of L‐α‐hydroxyacid oxidase isozymes in the mouse
Authors: Miles Joanna L. , Holmes Roger S. 
Published: June 2005

AbstractMouse liver hydroxyacid oxidase isozymes are present at low levels at birth and increase inactivity until day 13 after which HAOX‐B almost disappears and HAOX‐A i s reduced to approximately one half the maximum level in the adult. Kidney HAOX‐G appears near day 13 post partum and increases until adultl evels are reached, the female having four times the activity of the male. The pregnant female has significantly lower levels of HAOX‐A and HAOX‐B in the liver and higher activity ofHAOX‐B in the kidney. Developmental changes occur in the extent of epigenetic modification of mouse liver HAOX‐A during theearly neonatal period.
Studies on cell differentiation: Inducing capacity of sulfhydryl‐containing amino acids on post‐nodal pieces of chick blastoderms
Authors: Lee Hsin‐yi , Kalmus Gerhard W. 
Published: June 2005

AbstractThe inducing capacity of sulfhydryl (SH)‐containing amino acids (cysteine and glutathione) on post‐nodal pieces (PNPs) of stage 4 chick blastoderms was investigated. PNPs were treated for different lengths of time with chick Ringer's solution (control group) or chick Ringer's solution containing cysteine or glutathione, followed by culturing for 2–10 days on Spratt‐Haas agar medium or on the chorioallantoic membrane of 8‐day chick embryos. Control PNPs rarely showed differentiation, but those treated with the amino acids for six hours or longer developed structures such as neural tissue, notochord, somite mesoderm, and nephric tubules. The pulsatile tissue was only seen in the PNPs cultured for four days or longer. Two‐four hours of treatment was too short to provoke induction in a statistically significant number of PNPs. The highest frequency of induction was noted in those pretreated with glutathione (8 μg/ml) for eight hours, followed by culturing for four days. The magnitude of the inducing capacity and toxicity of the amino acids were concentration dependent: a deleterious effect was observed at 14 μg/ml, the highest frequency of induction occurred at 8 μg/ml, but the frequency decreased as the concentration decreased; at 2 μg/ml all PNPs remained viable, but only a few (9–14%) showed differentiation. The inducing capacity of the amino acids was counteracted by equimolar concentrations of p‐chloromercuribenzoic acid or w‐chloroacetophenone. The effects of glutathione (8 μg/ml) differed from those of Hensen's node grafts in that the former caused sublethal cytolysis and inhibited H3‐uridine uptake in competent ectodermal cells during the first 18 hours of cultivation.
Properties of the hatching enzyme from frog embryos
Authors: Katagiri Chiaki 
Published: June 2005

AbstractThe stage 18 Rana chensinensis embryos were deprived of their envelopes, and were reared until stage 21. The culture medium concentrated by lyophilization contains the enzyme (hatching enzyme; HE) which digests the whole egg‐envelopes of the homologous species. The enzyme also digests the outer egg‐jelly layers of a closely related species, but does not affect its inner layers and the whole envelopes of the less‐related anuran species. HE is a protease, as defined by its activity towards casein. Successive fractionation by (NH4)2SO4 precipitation, Sephadex gel‐filtration, and DEAE‐cellulose chromatography yielded a 100‐fold increase of proteolytic activity in the original culture medium. The molecular weight estimation by gel‐filtration gave a value of 55,000–60,000 for the HE. The pH optimum for the enzyme is 7.4–7.8. The enzyme is easily inactivated by preincubation at temperatures higher than 50°C, but is quite stable to autodigestion at pH 7.4. Its activity is unaffected by Na+, K+, and the soybean trypsin inhibitor, but is strongly inhibited by Ca++, Mg++, ethylenediaminetetraacetic acid, and diisopropyl‐fluorophosphate. The properties of the HE demonstrated here provide a basis for the view that this enzyme can be regarded as a unique protein functioning at the particular stage of embryogenesis.
The dicyemid mesozoa as an integrated system for morphogenetic studies. I. Description isolation and maintenance
Authors: Lapan Elliot A. , Morowitz Harold J. 
Published: June 2005

AbstractThe morphological simplicity of the dicyemid Mesozoa is such as to allow mapping of every individual cell during the development of the organisms. Individual cells are of a size amenable to micromanipulation and a number of potential morphogenetic markers is readily apparent. The possibility of raising the animals in vitro and obtaining developmental mutants makes these organisms excellent candidates for use as an integrated system to correlate cytodifferentiation and morphogenesis with genetic control.An axenic, nearly defined, medium in which the mesozoans can be kept for over three months has been developed. Methods for isolating and maintaining the organisms are described.
Coelomic fluid and blood serum proteins of the metamorphosing bullfrog tadpole
Authors: Thornburg Kent L. , Hillemann Howard H. , Martin Gordon W. 
Published: June 2005

AbstractBullfrog (Rana catesbeiana) tadpoles were divided into four groups containing Gosner ('60) stages as follows: I, 27–31; II, 32–36; III, 37–41; IV, 42–46. Extractable coelomic fluid volume from late metamorphic tadpoles (Group IV) was found to have a highly significant (p<0.001) negative correlation with stage; tadpole weight also had a negative correlation with stage (p<0.025). No significant correlation was found between coelomic fluid volume and tadpole weight. Group IV blood serum protein levels (x = 1.30 ± SEM 0.10 g/100 ml serum) were shown to be significantly higher than corresponding coelomic fluid serum protein levels (x = 0.80 ± 0.06 g/100 ml). Electrophoresis data demonstrated an increase in the albumin fraction of both blood serum and coelomic fluid during metamorphosis. I‐125 labeled human serum albumin equilibrated with the blood serum at equal concentrations about ten hours after an intracoelomic injection. A coelomic fluid turnover time of 26% per hour was calculated from the tracer data. We hypothesize that a slight sieving occurs at the coelomic fluid inflow site with none at the outflow site.
Parathyroid hormone preparations, salmon calcitonin, and urine flow in the South American lungfish, Lepidosiren paradoxa
Authors: Pang Peter K. T. , Sawyer Wilbur H. 
Published: June 2005

AbstractIn the South American lungfish, Lepidosiren paradoxa, injections of salmon calcitonin or bovine parathyroid extract have no effect on serum calcium levels. However, salmon calcitonin elicits a distinct diuresis. Crude or purified parathyroid extract or synthetic parathyroid hormone (1–34 fraction) produce a distinct antidiuresis.
Extensive and intensive factors determining the performance of striated muscle
Authors: Josephson Robert K. 
Published: June 2005

AbstractStriated muscle is obviously a versatile tissue, one which has been malleable to selective pressure and has become modified for many specific tasks. The variations which adapt striated muscle to particular functions involve both changes in its structural organization and changes in the chemical nature of its components. Although a number of factors have been identified which contribute to the diversity of muscle performance, it is not yet possible to account adequately for the wide range in muscle performance throughout the animal kingdom. While not a new direction in comparative physiology, developing quantitative explanations for the diversity of muscle performance is still an obvious, remaining task.
Hemoglobins and hemocyanins: Comparative aspects of structure and function
Authors: Bonaventura Joseph , Bonaventura Celia , Sullivan Bolling 
Published: June 2005

AbstractComparative studies of protein structure and function can be quite interesting by themselves, and even more interesting when interpreted with respect to an animal's physiology. In the case of fish hemoglobins, some success in the latter has been achieved but there are still many unsolved problems. It appears that comparative physiology and biochemistry have entered an era where results from comparative studies can shed a great deal of light on biochemical mechanisms in general. The trout hemoglobin system is an example. Distinctive hemoglobins in this system are presently being used as high resolution probes of the ligand‐binding mechanism. Characterization of the multiple, structurally distinct subunits of the 60S Limulus hemocyanin molecule may similarly aid in understanding its function.Our studies suggest the possibility of using Limulus hemocyanin and other hemocyanins as structural homologs and analogs of more complex macromolecular arrays. The rapid development of molecular structural data from X‐ray crystallographers combined with the vast data of comparative physiology and biochemistry makes this one of the most exciting areas in present day science.