bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in ion permeability and membrane potential during early echinoderm development: Electrophysiological and tracer‐flux determinations
Authors: Tupper Joseph T. , Powers R. Douglas 
Published: June 2005

AbstractAfter fertilization the membrane potential of the Asterias embryo undergoes an approximately fourfold increase in internal negativity, as measured by intracellular microelectrodes. Our previous experiments have demonstrated that the ionic basis of the membrane potential in this embryo may be described by a simplified form of the constant field equation. Using this relationship, the present experiments illustrate that the relative permeability of Na to K (PNa/PK) may be determined at any time during the early cleavage of this embryo. The results of these experiments indicate a relative increase of PK as related to PNa as the mechanism responsible for the large change in membrane potential. This has been confirmed by independent determination of absolute values for PNa and PK by means of 24Na and 42K tracer‐flux analysis. Experiments carried out during early cleavage demonstrate a greater than two fold increase in K permeability (3.8 × 10−7 cm/sec to 9.5 × 10−7 cm/sec) with no concurrent alteration in Na permeability (0.1 × 10−7 cm/sec). PNa/PK in 15 minute and two hour post‐fertilized embryos is 0.03 and 0.01 respectively. Its magnitude is the same whether determined by the constant field assumption or from tracer‐flux analysis. These changes in ionic permeability occur on a time scale which is similar to that of increased metabolic and synthetic activities in other echinoderm embryos. A possible regulatory role in the early differentiation of this embryo is discussed.
Bud initiation in a non‐budding strain of hydra: Role of interstitial cells
Authors: Moore Linda B. , Campbell Richard D. 
Published: June 2005

AbstractA non‐budding strain of Chlorohydra viridissima has been maintained by vegetative propagation and used to study factors which initiate budding. These hydra can be induced to bud by implanting small pieces of normal tissue into their columns. The cellular bases of the non‐budding phenotype and the bud induction were investigated by means of grafting, radio‐autography, and histological methods. No differences in the proportions or appearances of the cell types were observed between non‐budding and normal animals. However, induced buds have higher proportions of interstitial cells and their derivatives (nerves and nematoblasts) than do normal buds. Many of these interstitial cells and derivatives origihate from cells in the grafted implant, as demonstrated by using 3H‐thymidine labeled implanted tissue. Normal tissue from which interstitial cells have been previously removed will not induce buds in non‐budding hydra. We conclude that bud induction is mediated by migratory interstitial cells, and that the non‐budding strains of hydra owe their phenotype to a deficiency in those interstitial cell differentiation events which are necessary for bud initiation.
Developmental change in morphogenetic properties: Embryonic chick heart tissue and cells segregate from other tissues in age‐dependent patterns
Authors: Lesseps Roland J. 
Published: June 2005

AbstractDuring animal development complex morphogenetic movements occur. If these movements are controlled by cell‐to‐cell adhesiveness, the latter should change during embryonic development. To test this possibility indirectly, heart cells or tissue fragments from chick embryos of one and one‐half to five days of incubation were paired in separate experiments with five‐day pigmented retina or neural retina or 36‐hour neural tube. The combinations were made either by fusing together intact tissue pieces or by aggregating mixed cell suspensions dissociated from tissue pairs. All fused pieces and aggregates were cultured for two and one‐half days. The heart cells and tissue fragments from young embryos (1.5–2 days of incubation) displayed a tendency to take up external positions when combined with neural tube. In contrast, heart cells and tissue fragments from older embryos (4–5 days of incubation) tended to take up internal positions when combined with neural tube. A similar result (young heart outside, old heart inside) was found when combinations of heart fragments were made with pigmented retina fragments. When heart fragments of varying developmental ages were fused with neural retina, the older heart pieces were completely covered by neural retina, whereas younger heart pieces were only partially, if at all, covered by neural retina. These results clearly indicate a change in morphogenetic properties of embryonic heart cells during these early developmental stages. The interpretation is that the heart cells are gradually increasing their cell‐to‐cell adhesiveness, passing from a less adhesive condition at one and one‐half days to a more adhesive condition at four days of incubation.
Intracellular localization of lens antigens in the developing eye of the mouse embryo
Authors: Van De Kamp Maarten , Zwaan Johan 
Published: June 2005

AbstractThe time of initial synthesis and the subsequent localization of the crystallins in the embryonic mouse lens were studied with antisera to adult mouse lens using the indirect fluorescent antibody technique. Fluorescence was first detected in a few centrally located cells of deeply invaginated lens rudiments (10.75 to 11 days of gestation), after a prolonged period of contact between presumptive lens and presumptive retina. The reaction usually was restricted to the basal cytoplasm of these cells. During formation of the lens vesicle in 11 to 11.5 day embryos a gradually increasing fraction of lens cells began to display fluorescence, throughout their cytoplasm. At the time of closure of the vesicle the reaction had spread throughout the posterior wall. After fiber elongation became distinct, the cells of the anterior lens epithelium began to fluoresce (11.5 days). All cells of the lens rudiment were uniformly fluorescent in 12 day embryos and in all subsequent prenatal stages. Reactions were never observed outside the lens. We concluded that the mouse crystallins are tissue specific proteins and that their production begins at a relatively late stage of lens morphogenesis.When cells first showed fluorescence, they always had an elongated shape and their nuclei were in a basal position, close to the optic cup. A few hours later dividing cells became positive. Taking into account earlier found relations between cell shape and cell cycle phase, these observations may indicate that crystallin synthesis is initiated in the late S‐ or early G2‐phase of the cell cycle, and that embryonic lens cells retain the capacity to divide, even after acquiring large amounts of tissue‐specific structural proteins.
Chemical estimates of the RNA and DNA contents of the early mouse embryo
Authors: Olds P. J. , Stern S. , Biggers J. D. 
Published: June 2005

AbstractDNA and RNA were extracted from mouse embryos at several stages prior to implantation. RNA was measured by extinction at 200 nm, and DNA by a fluorometric assay. The mean values of RNA in the ovulated oocyte, 1‐cell, 2‐cell, and blastocyst‐stage embryo were 0.554, 0.545, 0.396, 0.458, and 1.37 ng, respectively. The mean values of DNA in embryos at these same stages were 23.8, 29.3, 41.1, 155, and 439 pg. There was no significant rise in total RNA per embryo until after the 8‐cell stage. The amount of DNA in mouse spermatozoa was also measured, and found to be 3.8 pg per spermato‐zoan. From this study it is clear that the mouse oocyte and early embryo do not contain the large quantities of DNA, in excess of the diploid value, found in some amphibian and invertebrate eggs.
The development of isolated blastomeres in Bithynia tentaculata (prosobranchia, gastropoda)
Authors: Verdonk N. H. , Cather James N. 
Published: June 2005

AbstractThe development of isolated blastomeres, separated at the first and second cleavage has been studied. After separation at the first cleavage, one half‐embryo (CD) becomes swollen and balloon‐like and develops adult organs such as eyes, tentacles, shell, operculum, etc. The other half (AB) is much more compact and never develops these adult structures.After separation on the alternate axis at the second cleavage to produce AD and BC halves, both halves could form all adult structures.These results indicate an equivalent organizing capacity of the C and D quadrants contrary to most spiralians, such as Ilyanassa, where the D quadrant alone exerts the major organizational influence.The experimental evidence is discussed in relation to the distribution of the cytoplasmic vegetal body, rich in RNA, which is passed to the CD blastomere in the polar lobe and then evidently equally distributed to C and D.
The adaptive response of the salt glands of adult mallard ducks to a salt water regime: An ultrastructural and tracer study
Authors: Martin B. J. , Philpott Charles W. 
Published: June 2005

AbstractThe salt glands of adult domestic mallards that had been maintained in three different physiological conditions were studied ultrastructurally. With adaptation to salt water conditions, the glands approximately doubled in size. This size increase appeared to result entirely from hypertrophy of the secretory cells which became a labyrinth of mitochondria filled basolateral interdigitations. The extent of the extracellular spaces and the complexity of the surface amplification was delineated by horseradish peroxidase and lanthanum salts. Tracer studies provided evidence that the junctional complexes may not always contain typical “tight junctions.” The ultrastructure of the gland is discussed in relation to the standing gradient osmotic flow hypothesis of Diamond.
Acetylcholinesterase in singly and multiply innervated muscles of normal and dystrophic chickens
Authors: Wilson B. W. , Linkhart S. G. , Nieberg P. A. 
Published: June 2005

AbstractAChE isozymes, localization and activities of multiply innervated anterior latissimus dorsi (ALD), singly innervated posterior latissimus dorsi (PLD) and mixed semispinalis capitis muscles from 2, 6 and 12 week normal and dystrophic chicks were studied. AChE forms characteristic of chick embryo muscles were maintained in normal ALD and semispinalis muscles and lost in normal PLD muscles after two weeks of age. Dystrophic ALD and semispinalis muscles were similar in their AChE forms, localization and levels to their normal counterparts. Dystrophic PLD muscles exhibited embryo AChE forms, high AChE activity and AChE outside of the neuromuscular junctions within the sarcoplasm of the muscle fibers. The data suggest that tonic fibers of the chicken lack and that dystrophic fast twitch fibers are defective in a system that suppresses embryo AChE forms after hatching.
The pentose shunt in wild‐type and glucose‐6‐phosphate dehydrogenase deficient Drosophila melanogaster
Authors: Geer B. W. , Bowman J. T. , Simmons J. R. 
Published: June 2005

AbstractFour‐day old Drosophila melanogaster homozygous or hemizygous for the glucose‐6‐phosphate dehydrogenase mutant allele, Zw−, possess slightly less than 10% as much glucose‐6‐phosphate dehydrogenase activity in whole‐fly homogenates as their wild‐type, Zw+, counterparts. The reduction of glucose‐6‐phosphate dehydrogenase activity in Zw− adults had no effect upon 6‐phosphogluconate dehydrogenase, phosphofructokinase, or malic enzyme activities. However, activities of the non‐oxidative pentose shunt enzymes were significantly greater in Zw− adults than in Zw+ adults. Radiotracer procedures indicate that the oxidative phase of the pentose shunt is blocked in Zw− adults. Zw− larvae grow less well on a defined minimal amino acid diet lacking fatty acids and whole nucleic acid than do Zw+ larvae, indicating that Zw− individuals have a lower biosynthetic capacity than Zw+ individuals.
A cytostatic factor in amphibian oocytes: Its extraction and partial characterization
Authors: Masui Yoshio 
Published: June 2005

AbstractIn mature unfertilized Rana pipiens oocytes a cytoplasmic substance exists that arrests mitosis at metaphase when injected into blastomeres. This is called “cytostatic factor (CSF)”. CSF is found to be inactive in fertilized eggs. CSF is extractable in a stable form with an extraction medium containing Ca++. In the absence of Ca++ it is inactivated during storage. CSF is not dialyzable and precipitates in ammonium sulfate solution between 20 and 30% saturation. Heat treatment at 55°C for 30 min inactivates CSF. RNAase treatment inactivates CSF, but protease treatment does not. Roles of CSF and Ca++ in oocyte activation at the time of fertilization are discussed.
Dorsal unpaired median insect neurons make neurosecretory endings on skeletal muscle
Authors: Hoyle Graham , Dagan Dani , Moberly Betty , Colquhoun William 
Published: June 2005

AbstractThis report presents results of a study in Schistocerca gregaria of large dorsal unpaired median neurons found previously in ganglia of several insects (Crossman et al., 171a; Hoyle, unpublished). Most of these neurons give off a single median neurite that makes a T‐branch, providing symmetrical left and right efferent axons. These axons emerge in ganglion nerve trunks and terminate in each of two nerves. They then travel to major skeletal leg muscles. One of the neurons supplies only the extensor tibiae (jumping muscle). The final branches of this neuron parallel the fast axon and supply muscle units that receive the fast axon only. All the muscle fibers in a unit are innervated (multiterminally) by the fast axon, but only a few receive terminals of the dorsal neuron in addition. The endings are of neurosecretory type, containing large numbers of dense core vesicles. Their function is unknown.
Response of the adult newt ventricle to injury
Authors: Oberpriller John O. , Oberpriller Jean C. 
Published: June 2005

AbstractA study was made of the response of adult newt ventricle to injury. The major events in the repair process after wounding involve blood clot formation, coagulation necrosis, macrophagic activity, regenerative activity of heart muscle, and connective tissue formation. Light microscopic autoradiography indicated that there was a definite area of labeled cells in trabeculae adjacent to the wound, beginning at about ten days after injury. Electron microscopic autoradiography confirmed that myocytes containing myofibrillae underwent DNA synthesis. It was concluded that adult newt myocardium is capable of reacting to injury by the proliferation of myocytes at the wound area as indicated by both DNA synthesis and mitosis.
Acceptance and sustenance value of naturally occurring sugars fed to newly emerged adult workers of honey bees (Apis mellifera L.)
Authors: Barker Roy J. , Lehner Yolanda 
Published: June 2005

AbstractThirteen sugars were fed in 0.125, 0.5, and 2 M solutions in water and in 0.5 M sucrose: L‐arabinose, D‐xylose, D‐fructose, D‐glucose, D‐galactose, D‐mannose, lactose, maltose, melibiose, sucrose, trehalose, melezitose, and raffinose. Survival, water consumption, and sugar consumption were measured. No sugar equaled sucrose in acceptance or sustenance. Reduced survival seemed to be associated with aldoses that contain axial hydroxyl groups at C2 or C4 in a C1 pyran ring (mannose, galactose, or arabinose) even if they were in a sucrose solution that ensures feeding. Acceptance was correlated with survival, but whether low acceptance is a consequence or a cause of mortality was not established. When 0.5 M sucrose was supplied separately, bees showed a strong preference for the sucrose solution and were not harmed by small quantities of the other sugars.
The structural protein of reptilian scales
Authors: Baden Howard , Sviokla Sylvester , Roth Irwin 
Published: June 2005

AbstractPrevious studies of reptilian epidermis have shown that scales contain both a and feather fibrous proteins. The outer stratum (feather) and inner stratum (a) of snake (Boa constrictor) scales were separated and the tissue extracted with 6 M urea in 0.1 M Tris, pH 9.0, with 0.1 M mercaptoethanol. Following alkylation to the S‐carboxymethyl derivatives (SCM), the proteins were separated on the basis of their solubility at pH 4.5. X‐ray diffraction analysis indicated that pH 4.5 insoluble proteins represented the fibrous proteins while the soluble ones had the characteristics of matrix material. Disc electrophoretic patterns and amino acid analyses of the two types of fibrous proteins were different while those of the matrix proteins from both strata appeared to be very similar. The epidermal proteins of shell (feather) and extremity (a) skin from turtle (Pseudemys) were similarly isolated and shown to have different amino acid compositions. Although separation of the various components by differences in their solubility at pH 4.5 was not possible, a comparison of electrophoretic patterns suggested that the proteins extracted from the epidermis of the shell and extremity skin had different fibrous but similar matrix proteins. These studies indicated a strong similarity between reptilian scales and hair, where fibrous and matrix proteins are present and are separable on the basis of the solubility of their SCM derivatives. Although the a and feather fibrous proteins form filaments of very different size, it appears that they are associated with similar matrix proteins.
Effects of cell density on the expression of differentiation by chick embryo chondrocytes
Authors: Solursh Michael , Meier Stephen 
Published: June 2005

AbstractIn this report the effects of cell density on the expression of differentiation by chick embryo sternal chondrocytes is studied. Differentiation is simultaneously assayed in terms of the rate of synthesis of collagen and acid mucopolysaccharide and in terms of the distribution of newly synthesized acid mucopolysaccharide between the cells and the culture medium. Cell density is studied first in terms of the number of cells per plate and second in terms of the size of aggregates of cells. First, when cultures, started‐with 104 cells/60 mm dish, are studied over time, it is observed that the rate of synthesis of collagen and acid mucopolysaccharide increases faster than accountable for by the growth rate. Because conditioned medium placed on cultures grown in fresh medium can rapidly enhance mucopolysaccharide synthesis relative to the growth rate, it is suggested that conditioning of the culture medium might contribute in part to the observed rapid acceleration of the expression of differentiation with time in culture. Second, when cultures are started with small inocula so that large aggregates of cells form before cultures reach stationary phase, both the rate of synthesis of specialized products and the ability of cells to retain acid mucopolysaccharides is promoted. It is suggested that accumulated matrix might provide a microenvironment that itself promotes better expression of the cartilage phenotype.
Wound healing in Eisenia foetida (oligochaeta). 1. Histology and 3H‐thymidine radioautography of the epidermis
Authors: Burke Janice M. 
Published: June 2005

AbstractWhen the eight most anterior segments of Eisenia foetida are removed the wound is provisionally closed by a plug of coelomocytes surrounding an everted or retracted esophagus. Usually within one to three days the wound is definitively covered by migration of the columnar cells from the adjacent epidermis over the coelomic plug. Epidermal basal and gland cells do not directly take part in wound epithelialization.In the normal epidermis 2.3% of the cells incorporate 3H‐thymidine during a labeling period of one hour. The incorporation rate for the columnar cells is higher than that for the basal cells and the gland cells are not labeled. During the period of wound covering by the epidermis (the first three days after transection) the DNA synthetic rate for basal cells and columnar cells drops steadily in both the segment bordering the wound and for at least four segments posteriorly. At four and five days the labeling rate for the epidermis of the segment near the wound rises sharply to beyond the control levels (3.7%) then drops again abruptly at six to seven days (0.8%). Two to four segments posterior to the wound the incorporation rate remains at the low 3‐day level throughout the first week after transection.
Cell aggregation: Properties of cell surface factors from five species of sponge
Authors: McClay David R. 
Published: June 2005

AbstractAggregation factors isolated from the cell surface of five species of sponge are shown to be specific in their ability to enhance cell aggregation. Factors from Haliclona viridis, Haliclona variabilis, Tedania ignis, Homaxinella rudis, and Dysidea crawshayi each exhibit the species specific enhancing effect and have no such effect in heterospecific cell‐factor combinations. Radioactively labeled cell free supernatant materials are shown to bind selectively to homospecific cells suggesting that cells contain specific receptors for attachment of the aggregation mediating materials. Finally, in several heterospecific combinations there was an inhibition of cell aggregation. The inhibitory agent was separated from the enhancing factor chromatographically. After removal of the inhibitory substance, the enhancing factor was still active in promoting cell aggregation of the homospecific cells only.
Ultrastructural autoradiography and cytochemistry of the iodine‐binding cells in the ascidian endostyle
Authors: Dunn Ann D. 
Published: June 2005

AbstractThyroid‐like activity was investigated in the endostyles of Molgula manhattensis, M. occidentalis and Styela plicata. Animals were immersed in sea water containing 125I for one to 24 hours. Although electron microscopic autoradiography revealed an extracellular accumulation of silver grains associated with zone 8 in all three species and with zone 9 in two of them, intracellular accumulations were found only in zone 7. Within this zone in each of the three species, grains were present over the apical cell membrane, multivesicular bodies and the apical cytoplasmic matrix after brief exposure to 125I. After longer exposure, grains were also present over large dense bodies and more basal regions of the cytoplasmic matrix.Certain features, suggestive of thyroidal functions, were observed in the cells of zone 7. These included morphological evidence for secretory and pinocytotic activities and cytochemical evidence both for peroxidase activity and for the presence of carbohydrate material which may represent a glycoprotein.It is concluded that active binding of iodine is restricted to zone 7 in the endostyles of Molgula and Styela, where it occurs at both the apical cell membrane and within multivesicular bodies. Some of the iodinated product may be immediately passed into the lumen of the pharynx. The rest is stored intracellularly within multivesicular bodies and dense bodies of zone 7. Intracellular binding and storage of iodine are considered to represent primitive conditions preceding the evolution of the follicular structure of the thyroid gland.
Influence of diet on sugars found by thin‐layer chromatography in thoraces of honey bees, Apis mellifera L.
Authors: Barker Roy J. , Lehner Yolanda 
Published: June 2005

AbstractTwelve sugars in 0.5 M solution in water and also in 0.5 M solution in 0.5 M sucrose were fed to newly emerged, caged honey bee workers. After 11 to 27 hours, the sugars of ice water extracts of degutted thoraces were promptly analyzed by thin‐layer chromatography.Unlike published values for sugars in the hemolymph from healthy bees, trehalose was the predominant sugar in the thorax. Lesser amounts of glucose and only traces of fructose were found. Trisaccharides were found in the thorax after they were fed to bees.Progress was made toward determining which nonsustentative sugars are toxic and which are not accepted. Galactosides seem toxic per se and not to be progenitors of toxic galactose. Galactosides and mannose gave no buildup of a particular sugar to indicate metabolic blockage. Starved bees and moribund bees with empty crops contained glucose but no trehalose. Analysis of thoracic sugars has potential value in diagnosis of bee poisoning.