bluuebunny/crossref_metadata_2025_split huggingface dataset:
The degradation of lactate dehydrogenase isozymes injected into frog eggs
Authors: Rauch Nancy 
Published: June 2005

AbstractLactate dehydrogenase (LDH) isozymes from beef tissues were injected into newly fertilized frog eggs. Embryos at various stages were examined by starch gel electrophoresis to determine whether the injected isozyme was present. Beef LDH‐1 was stable for at least twelve days following injection, while beef LDH‐5 was present in the embryos as a functional molecule for less than six days. These very different in vivo stabilities are not in agreement with the in vitro stabilities obtained here, and suggest that regulated differential stability of isozymes may be important to the organism in conferring greater metabolic flexibility during cell differentiation when the isozyme repertory commonly changes. During the degradation of beef LDH‐1, no hybrid beef‐frog LDH molecules could be detected although such molecules can be formed by a simple in vitro technique. Since frog LDH is synthesized during the degradation of the injected LDH, the lack of detectable hybrid molecules indicates that the subunits of the degraded molecules cannot be reused—either because the molecule is degraded as a whole, without the release of subunits, or because the sites of synthesis and degradation are mutually inaccessible.
Effects of castration and/or hypophysectomy on the seminal vesicles of the catfish, heteropneustes fossilis (Bloch)
Authors: Sundararaj Bangalore I. , Nayyar S. K. 
Published: June 2005

AbstractThe response of the seminal vesicles to hypophysectomy and/or castration during the prespawning and the spawning periods was studied. Forty days post‐hypophysectomy the seminal vesicles regress completely, whereas 40 days postcastration they show hyperactivity which is accentuated by 85 days post‐surgery. Further, catfish castrated in the prespawning period of 1966 not only show hyperactive seminal vesicles in that season but also exhibit hypersecretory seminal vesicles in the following breeding season, in spite of the absence of the testes. In the castrate catfish, hyperactivity in the seminal vesicles is accompanied by a significant increase in the number and activity of the granulated basophils in the pituitary and an increase in the nuclear diameter of the interrenal cortical cells. Two hypotheses are proposed to explain this paradoxical phenomenon.
The ultimobranchial body of Rana pipiens. X. Effect of glandular extirpation on fracture healing
Authors: Robertson Douglas R. 
Published: June 2005

AbstractFracture healing of the tibiofibula was examined in the frog, Rana pipiens, in which the ultimobranchial glands were removed. Extirpation of these structures presumably eliminates the hormone calcitonin. X‐ray and histological observations were made during the healing process of a closed fracture for a period of 12 weeks. The repair process of fractured bone in the first four weeks of intact and ultimobranchialectomized frogs revealed similar tissue reactions at the fracture site and followed comparable healing patterns. There was extensive cartilage formation in both groups with ossification at the periphery of diaphyseal cartilage. After eight weeks the fracture site of controls exhibited more extensive invasion and development of endochondral ossification than ultimobranchialectomized frogs. Osteoclasts were observed at the distal segment of the fracture, and throughout endochondral trabeculae. After 12 weeks, periosteal bone was well developed in controls, and poorly represented in ultimobranchialectomized frogs. Deprivation of calcitonin in frogs apparently does not affect cellular activity at a fracture site during the first four weeks. However, cellular activity is greatly reduced with a concomitant reduction in calcification after 8 and 12 weeks. This latter period corresponds to increased osteoclastic activity in ultimobranchialectomized frogs. Further, retarded repair process may also be influenced by serum calcium levels rather than by a lack of direct hormonal control on specific bone cells types.
Acid phosphatase in the tail of Xenopus laevis during development and metamorphosis
Authors: Robinson Helen 
Published: June 2005

AbstractQuantitative and qualitative changes in acid phosphatase during growth and metamorphosis of the tail of Xenopus laevis have been investigated. Enzyme activity was assayed by two methods using different substrates, p‐nitrophenyl phosphate and β‐glycerophosphate. The enzyme was found to be consistently more active with p‐nitrophenyl phosphate. Specific activity of whole tail homogenates assayed by both methods remains constant during development and early metamorphosis, and then rises sharply as the rate of tail regression begins to accelerate. Total phosphatase activity of whole tail homogenates rises linearly during development and early metamorphosis, and then maintains a high level during the first half of the period of tail regression. After this it declines. Regional localization of acid phosphatase activity has been determined in different parts of the tail: dorsal fin, ventral fin, and muscle. Changes in the apparent Km and pH optimum of acid phosphatase occur during tail regression. These properties remain constant during development and early metamorphosis, and are then found to change approximately in parallel with changes in enzyme activity during tail resorption. Possible implications of these biochemical events are discussed.
Juvenile hormone effects on chromosomal puffing and development in Chironomus thummi
Authors: Laufer Hans , Holt Thomas K. H. 
Published: June 2005

AbstractSeveral larval stages of the dipteran Chironomus thummi were treated with a synthetic juvenile hormone (JH) mixture. Treatment resulted in larvae which underwent the first three molts, but thereafter development was arrested; many were incapable of completing the larval‐pupal molt. The pattern of chromosomal puffs in the prepupal salivary gland was examined at 91 loci: nine pupal puffs which were consistently active in controls were found to be reduced following treatment; one puff, Balbiani ring IV b, was enlarged. Autoradiographs indicate intensive RNA synthesis at Balbiani ring IV b, but depressed synthesis at the other nine affected loci. The puffing pattern demonstrates for the first time in detail specific effects of chemical compounds with JH activity on chromosomal puffs. Compounds exhibiting JH activity may regulate transcriptional activity at specific gene loci, and specific alterations in RNA synthesis may account for alterations in the course of metamorphosis.
A role of inductive factors in interstitial cell differentiation in hydra
Authors: Lesh Georgia E. 
Published: June 2005

AbstractThe distribution of interstitial cells and I‐cell derivatives in hydra is asymmetrical. This asymmetry is expressed apico‐basally along the stalk and radially with respect to cell layer. An inductive factor concentrated from the tissues of hydra alters this expression of polarity (Lesh and Burnett, '66).To test the hypothesis that quantitative differences in the concentration of this inducer effect qualitative differences in I‐cell differentiation, regenerating annuli were exposed to tissue extracts containing varying levels of inductive activity. Two types of extracts were employed: (1) serial dilutions of an active extract; and (2) extracts from different species of hydra exhibiting decreasing levels of inductive capacity. Hydra pirardi annuli were incubated four hours in extract. After 24 hours annuli were fixed, sectioned, stained, and counts made of all cell types.Statistical analyses of these counts show that responding cell types demonstrate one or both of two responses: proliferation and/or differentiation. The initial response in normal annuli is a 1.9 ± fold increase in the proportion of I‐cells present. Annuli which undergo an increase in I‐cell complement before incubation develop alterations in the distribution of I‐cell derivatives. At concentrated inducer levels isorhiza cnidocytes (epidermis) and mucus cells (gastrodermis) differentiate. At lower concentrations stenotele cnidocytes and gland cells appear. The distribution of epithelio‐muscular cells and digestive cells (not I‐cell derivatives) is independent of inducer concentration.Also, the distribution of I‐cells and derivatives found after the experimental treatments coincides directly with the distribution of these cell types relative to the inductive regions of intact hydra.
Differentiation of cartilage and bone from common germinal cells. I. The role of acid mucopolysaccharide and collagen
Authors: Hall B. K. 
Published: June 2005

AbstractThe differentiation of cartilage and bone from common germinal cells on the membrane bones of the embryonic chick has been investigated to test the hypothesis that acid mucopolysaccharides (chondroitin sulphate) and collagen play a role in controlling the pathways of differentiation open to the germinal cells. Injection of cortisone acetate was used to suppress sulphation of chondroitin to chondroitin sulphate and injection of vitamin C to stimulate collagen synthesis. Of the membrane bones studied 60–80% exhibited suppression of chondrogenesis, indicating that chondroitin sulphate and/or collagen play important roles in the control of chondrogenesis.Mechanical stimulation and hypoxia have been related to chondroitin sulphate synthesis in proposing a mechanism to explain the differentiation of cartilage and bone from common germinal cells.
Alteration of nucleolar ultrastructure in iris epithelial cells during initiation of Wolffian lens regeneration
Authors: Dumont James N. , Yamada Tuneo , Cone M. Virginia 
Published: June 2005

AbstractMorphological aspects of nucleoli of iris epithelial cells participating in Wolffian lens regeneration in the adult newt (Triturus viridescens) were studied with electron and phase‐contrast microscopes at various times after lens removal. In normal condition, the nucleoli appear as small, compact bodies composed of fibrous elements. The granular element is often lacking, but when present, is sparse and located at the periphery of the organelle. Within two days after lens removal, the size of the nucleolus increases, and its shape becomes complex and diversified. The granular element increases in absolute as well as relative amount. Granular and fibrous components become intermingled and together form the fibrogranular region. Portions of this region often project from the nucleolus as coarse threadlike extensions that become a prominent feature. Morphogenesis of the organelle continues during the subsequent two days. In parallel with these structural changes, the number of nucleoli per nucleus and the frequency of nuclei containing nucleoli increases. All these changes start in the nondividing phase of the iris epithelium before induced cell division. These changes in nucleoli are the earliest so far observed in iris epithelial cells after lens removal, and coincide in time with the activation of ribosomal RNA synthesis previously observed in this system.
Localization of lactate dehydrogenase activity in the cells of the fish (Xiphophorus helleri) eye
Authors: Whitt Gregory S. , Booth Gary M. 
Published: June 2005

AbstractThe swordtail (Xiphophorus helleri) eye contains the A4 and B4 isozymes of lactate dehydrogenase (LDH) as do all vertebrates and in addition contains a distinctive lactate dehydrogenase, the E4 isozyme, found only in fish. LDH in the fish eye is located predominantly in the neural retina, especially in the inner segments of the photoreceptor cells. This neural retinal LDH activity consists mainly of the B4 and E4 isozymes which are more resistant than the A4 isozyme to inhibition by 1.8 M urea. The sclera, cornea, and lens possess mainly the urea‐sensitive A4 isozyme. The specific cellular location of the E4 isozyme suggests that it plays a role in the biochemistry of vision.
The cellular mechanism of the formation of a regeneration blastema of fresh‐water planaria, Dugesia dorotocephala. I. The behavior of cells in a tiny body fragment isolated in vitro
Authors: Betchaku Teiichi 
Published: June 2005

AbstractSmall fragments of 0.1 mm3 to 0.03 mm3, too small to regenerate the whole organism and yet containing a variety of tissues were taken from the prepharyngeal portion of a fresh‐water planaria, Dugesia dorotocephala. They were cultured in saline solution and histologically examined at intervals. Morphological rearrangement of tissues was completed in two days, coinciding with the time reported as necessary for the formation of an ordinary regeneration blastema. This was the result of the interactions of isotypically aggregating epidermis, gastrodermis and inner composite‐tissue, and involved neither dedifferentiation nor differentiation. The parenchyma accounted for most of the motility of the inner composite‐tissue layer. Furthermore, fixed parenchyma cells and neoblasts segregated in the portion of the parenchymal aggregate which was exposed to the saline solution, resulting in the aggregation of neoblasts in the periphery. This parenchymal segregation is considered due to differences in susceptibility to environmental conditions of these two parenchymal cells in addition to differences in motility and adhesiveness. The population of neoblasts thus aggregated was observed to increase by mitosis. A regeneration blastema appears to from by the local cellular segregation triggered by an injury under hypotonic conditions and not by the extensive migration of any particular cell type to the site of the wound. Less motile tissues, such as muscles and nerves, may account for the regional characteristics of the regeneration field. A possibility of involvement of the old tissues in the growth of a blastema and in its histogenesis is discussed.
Resting membrane potential in chick muscle cells during ontogeny
Authors: Boëthius Jörgen , Knutsson Evert 
Published: June 2005

AbstractResting membrane potentials were recorded from developing thing muscle cells of the chick at different stages from the third day of incubation. During the early stages the membrane potentials were lower than in the adult animal. No significant changes in potentials were observed until after the fifteenth day. There was a marked increase between the fifteenth and nineteenth days, and the membrane potential reached values comparable to those of the adult. In a study of the concomitant morphological development, the increase in membrane potentials was found to coincide with the transformation of the majority of the cells from myotubes to myocytes.
Sodium extrusion induced by ammonium ions in toad skeletal muscle
Authors: Beaugé L. A. , Ortiz Olga 
Published: June 2005

AbstractA study was made of the ability of ammonium ions to stimulate active sodium extrusion in toad skeletal muscle. In sodium‐rich muscles, 15 mM ammonium induced a net loss of sodium against a concentration gradient slightly larger than 5 mM potassium. Similar results were obtained when a sodium efflux was considered. The activation curve of ammonium‐stimulated sodium efflux was strongly S‐shaped, reaching a plateau at 10–15 mM ammonium; this could be due to more than one activation site on the outside membrane, or to some cooperative effect of ions. The increment in the rate constant for sodium efflux produced by both ammonium and potassium was completely abolished by 10−4 M ouabain. The extent of the inhibition by a submaximal dose of this glycoside was independent of the external ammonium concentration up to 30 mM. This behavior corresponds to a non‐competitive type of inhibition.
Cortical morphogenesis in Paramecium aurelia following amputation of the anterior region
Authors: Chen‐Shan Lily 
Published: June 2005

AbstractThe most anterior approximately 35 μ of the 49–50 μ long anterior region was removed from many paramecia by a transverse cut. The challenge imposed by the amputation met with the following responses in lines of successive proters (anterior products of fission).
Restitution of the anterior region in successive proters. Most of the restitution occurred at the first fission which yielded proters having anterior region about 55% (as compared with the approximately 30% remaining after amputation) and posterior regions 68% of normal length. Return to normal was nearly complete after the eighth fission.
Incomplete kineties in successive proters. The anterior termini of incomplete kineties came to be located more and more posteriorly in the course of successive fissions as growth occurred anterior to them. When the anterior termini came to be posterior to the fission plane, they were lost from the proters formed at this and subsequent fissions. Proters with reduced kineties were slenderer than normal.
Dorsal kinety pattern in the proters. On the dorsal field, after all short kineties were lost from the proters, the remaining kineties were normally oriented anterior‐posteriorly. However, the normal arrangement of the anterior termini of kineties at the suture, on the dorsal anterior tip of the proters, was lacking.
Ventral kinety pattern in the regenerated anterior region. Regenerated anterior regions possessed normal or nearly normal ventral kinety patterns. Deviations from normal were minor.
The preoral suture. Normally this is a clear space at the juncture between the anterior ventral right and left field. The regenerated part of the suture was atypical: the clear space was lacking.
Inheritance and variation of total number of kineties around the cell. In a slender clone, the mean number of kineties was 67 as compared with 75 in an uncut control clone. The difference was inherited for many fissions, but not permanently. Normally, the number of kineties decreases slowly when fission rate is low due to limitation of food and rises slowly when excess food is supplied.
Abnormal buccal structures. Cuts made close to the vestibule, but not those further from the vestibule, resulted in death or in abnormal clones with defective buccal structures of various sorts.
The effects of pressure on cell division and oral morphogenesis in Tetrahymena
Authors: Simpson Robert E. , Williams Norman E. 
Published: June 2005

AbstractThe effects of brief exposures to high hydrostatic pressure on cell division and oral morphogenesis in synchronized Tetraphymena have been studied. The results indicate a “transition point” at approximately 45 minutes after the end of the synchronizing treatment. Prior to the transition point, pressure treatment produced long division delays and a correlated blockage or reversal of oral differentiation. Treatment with pressure after this time also blocked oral morphogenesis, but most cells continued to divide, and produced daughter cells with incomplete oral structures. After consideration of these data in relation to results with cycloheximide and colchicine, we suggest that the effects of pressure on protein‐protein interaction may be responsible, at least in part, for the consequences of pressure application prior to the transition point, and may be entirely responsible for the effects found after the transition point. Cell development after the transition point in Tetrahymena, therefore, may be exclusively dependent on assembly processes.
Active polysomes in sea urchin eggs and zygotes: Evidence for an increase in translatable messenger RNA after fertilization
Authors: Denny Paul C. , Reback Patricia 
Published: June 2005

AbstractThe increase in polysomal material in sea urchin zygotes after fertilization occurs primarily as an increase in the number rather than in the sizes of the polysomes. This suggests that the protein synthesis system in eggs is messenger RNA limited and that polysomes form at fertilization as a result of the messenger RNA becoming available. While these findings do not rule out the possibility that the peptide initiation step is less efficient in eggs than in embryos, they do suggest that this step is not the principal cause of the inactivity of the protein synthesis system in eggs.
Developmental potentialities of blastema cell nuclei of the Mexican Axolotl
Authors: Dasgupta Sanjoy 
Published: June 2005

AbstractDuring amphibian limb regeneration, differentiated cells contribute to the formation of a blastema. Cells once incorporated into the blastema are identical in their morphological appearances. This investigation is a test of the developmental potentialities of blastema cell nuclei as revealed by means of nuclear transplantation.When blastula cell nuclei are injected into enucleated eggs, approximately 80–90% of the test eggs cleave. Over half of the cleaved eggs form regular blastulae. Of the regular blastuae 60% form post‐neurula embryos.The initial experiment with regenerating cells involved the ijection of two to three blastema cell nuclei from a seven‐day‐old regenerate into test eggs. The blastema cells were obtained from a white Axolotl (dd) and the test eggs were laid by a dark Axolotl (Dd). Of some 35 eggs injected, five partial and two regular blastulae were obtained. One of the regular blastulae was sacrificed after 24 hours of development, and part of its tissue was grafted on an embryo of the genetic composition DD. When the host started to develop its pigmentation, the graft developed as a white patch, thus indicating the genetic nature of the graft was that of transplanted blastema cell nucleus. Subsequently single blastema cell nuclei from seven‐ to sixteen‐day‐old regenerates were injected into test eggs. Blastema cell nuclei of eight‐day‐old regenerates were injected into test eggs. Blastema cell nuclei of eight‐day‐old regenerates were able to promote development of post neurula embryos.
Electrical correlates of neural superposition in the eye of the fly Sarcophaga bullata
Authors: Mote Michael I. 
Published: June 2005

AbstractResponses to light at focal recording sites in the lamina ganglionaris of the fly Sarcophaga bullata were investigated as a function of geometrical parameters of the stimulus. The mean receptive angle of the laminar response was 12° at 50% response, or about twice the value observed in single retinular units of other species, but in some cases it approached the 6° values reported for single retinular cells. Illumination of areas on the surface of the eye with focused light indicated that sensitivity at the recording site was greatest to illumination of certain facets distributed asymmetrically within the area, and forming an oblong or elliptical pattern. Simultaneously illuminated pairs of facets did not provide strong evidence for lateral interaction. Results are discussed in light of predictions made on the basis of the neural superposition model of Kirschfeld, and it is concluded that the response recorded in the lamina is representative of activity expected from the optic cartridges located in that region.
Compatibility in insect tissue transplantations. I. Ovarian transplantations and hybrid formation between Drosophila species endemic to Hawaii
Authors: Kambysellis Michael P. 
Published: June 2005

AbstractInterspecific larval ovarian transplantation between Drosophila species endemic to Hawaii revealed a remarkable uniformity of the internal environment among species of the picture‐winged group, in contrast to the high diversity observed for the mainland species. Various expressions of incompatibility were observed which were far less pronounced than in the case of the mainland species. The suitability of host environment for ovarian growth appears to be correlated with the rapid evolution of the group.The potentiality for gene exchange between species highly diversified morphologically and normally not interbreeding confirms the significance of ethological isolation in preventing species hybridization and indicates the conservative diversity in the genetic architecture of the picture‐winged species.The degree of chromosomal asynapsis observed in the hybrids between homosequential species could suggest the existence of differences in the fine structure of chromosomes. It further indicates the significance of point mutation in Hawaiian Drosophila speciation.