bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experiments concerning the cleavage furrow in invertebrate eggs
Authors: Rappaport R. 
Published: June 2005

AbstractDividing eggs of Echinarachnius parma, Hydractinia echinata, Cerebratulus fuscus and Mytilus edulis were subjected to experiments designed to yield additional information concerning the cytoplasm in the cleavage plane. Answers to the following questions were sought: (1) Will the base of the furrow cut itself upon a needle placed in its path at right angles to the cleavage plane? (2) What part of the surface is responsible for the constricted shape of the partly divided egg? (3) Does completion of furrowing depend upon a specific subsurface cytoplasmic arrangement? It was found that in no case could the base of the furrow cut itself upon a needle. The constricted shape of the partly divided Echinarachnius egg depends on the integrity of the surface at the base of the furrow. The eggs of all four species completed division despite drastic stirring and mixture of subsurface cytoplasm which was begun during early stages of furrowing and continued until the blastomeres were separated.
The effects of mercaptoethanol on cellular development in Tetrahymena pyriformis
Authors: Gavin Ray H. , Frankel Joseph 
Published: June 2005

AbstractThe effects of β‐mercaptoethanol on cell division, nuclear division, and oral morphogenesis were investigated in two strains of Tetrahymena pyriformis, WH‐6 (micronucleate) and GL (amicronucleate). Mercaptoethanol inhibited division in both strains. In exponentially growing cell cultures, cell multiplication stopped after a 30 minute lag (strain WH‐6); in synchronized cultures, division was prevented or very greatly delayed if the agent was added during the first 60% of the interval between the end of the last synchronizing shock and the synchronous division.In both strains, mercaptoethanol brought about an arrest of oral primordium development in cells which had not yet begun to form visible membranelles at the time of addition of the drug. In cells arrested just prior to the onset of membranelle development the oral primordia became disorganized and in many cases were gradually resorbed. In these cells micronuclear division was generally arrested (strain WH‐6) and macronuclear and cell division did not occur at all (strain WH‐6), or were resumed after a long delay (strain GL).Cells which were in stages of visible membranelle development at the time of addition of mercaptoethanol continued to develop. In strain WH‐6, all of these cells completed oral development and divided, while in strain GL about 40% of these cells were arrested in the course of membranelle development. In these arrested cells, the oral primordia were resorbed, and division did not take place.In the situations in which oral morphogenesis was completed and cell division took place in mercaptoethanol, micronuclear division (in strain WH‐6) was in all cases normally completed. Macronuclear division in strain WH‐6 was also normal at the minimum concentration (4 × 10−2M) which affected morphogenesis when added at earlier stages. However, at a somewhat higher concentration (5 × 10−2M) in strain WH‐6, and at the lowest concentration employed (1.5 × 10−2M) for strain GL, macronuclear division was either prevented (in both strains) or else rendered highly abnormal (in strain GL).These data suggest that mercaptoethanol blocks some process required for the initial organization of oral structures and for the division of the macronucleus. The nature of this process is discussed.
Increased sexual behavior in the male rat following lesions in the mammillary region
Authors: Lisk Robert D. 
Published: June 2005

AbstractCopulatory output of the mature male rat was measured over an eight week period under conditions of each male having free access to a constant stimulus female.Of 71 males tested 31 of these (44%) had to be discarded as they did not reach our arbitrary minimum criterion of producing copulation plugs on 4 out of 14 nights during the initial (control) observation period. An extreme individual variability in sex drive was noted among the animals used for further testing.Employing equal sized groups of about ten animals and using a two week interval as the basic unit of time; the mean sexual activity for the group measured as number of copulation plugs found and mean percentage of nights on which copulation occurred indicated an extreme similarity of all groups. Maximum sexual response occurred during the initial 14 day test period and both measures of activity used (copulation plugs and days on which copulation occurred) declined by approximately 50% over the eight week test period.A similar 50% decline in response occurred following lesions in the middle hypothalamus dorsal to the arcuate nucleus or lesions dorsal to the hypothalamus involving the habenula and surrounding cortex. It was concluded these areas are not involved in regulation of copulatory behavior in the male rat.Lesions in the mammillary region (mostly medial) resulted in 50% of the animals showing a sustained constant copulatory output during the eight week test, while the remaining 50% (mostly with lateral lesions) showed marked increases which expressed as the mean of the group amounted to 90% copulation plugs and 50% in nights on which copulation occurred.Thus it was concluded that structures in the mammillary region at the junction of the diencephalon and mesencephalon normally exert a regulatory (inhibitory) influence on the sex drive in the male rat.
Relation of impulse conduction to electrically induced release of neurosecretory material from the urophysis of the teleost fish Tilapia mossambica
Authors: Fridberg G. , Iwasaki S. , Yagi K. , Bern H. A. , Wilson D. M. , Nishioka R. S. 
Published: June 2005

AbstractThe caudal neurosecretory system of the teleost Tilapia mossambica was subjected in vivo and in vitro to intense and prolonged electrical stimulation. Repeated firing of neurosecretory units was observed in the in vivo preparations, and compound action potentials were recorded in vitro. Evidence of depletion of neurosecretory material from the urophysis was obtained on the light and electron microscope levels. Ultrastructurally two pictures were encountered in the responding axon terminals: (1) a decrease in electron density of most of the elementary neurosecretory granules in individual terminals; (2) complete or nearly complete disappearance of granules and vesicles from individual terminals. The latter picture is considered to be a more advanced stage of depletion.
The comparative submicroscopic cytology of the corpus allatum‐corpus cardiacum complex of wild type and fes adult female Drosophila melanogaster
Authors: King Robert C. , Aggarwal Surinder K. , Bodenstein Dietrich 
Published: June 2005

AbstractThe submicroscopic morphology of the corpus allatum‐corpus cardiacum complex of wild type adult female Drosophila melanogaster is described. These endocrine organs are compared with those of females homozygous for the recessive, female sterile gene, fes. The corpus allatum is known to produce a hormone influencing vitellogenesis. The ultrastructure of the gland suggests that this hormone is synthesized by a smooth surfaced, membranous system organized into a reticulum of filaments and tubules from which vesicles are derived by abscission of terminal and lateral blebs. The allatum cells of genetically ovatectomized, fes females are inhibited from releasing the hormone they synthesize. They swell and undergo characteristic, degenerative changes. The corpus cardiacum consists of a central bundle of axons surrounded by cortical cells. Many of the axons are thought to originate as projections from specialized, secretory neurons residing in the pars intercerebralis. Neurosecretory spheres are carried posteriorly in these axons by traveling bulges. The cortical cells contain myriads of neurosecretory spheres suspended in their cytoplasm, and most of these are believed to have been donated by contiguous axons. Cortical cells are also characterized by an extensive, rough surfaced, endoplasmic reticulum consisting of interconnected bloated cisternae which arise from localized, blister‐like proliferations of the outer membranes of the nuclei. The cortical cells of fes females also swell, and their nuclear blisters reach immense sizes. Vitellogenesis within a wild type ovary previously implanted into the abdomen of fes females is accompanied by release of products from the host allatum and cardiacum cells and the return of these cells to their normal morphologies.
Bicaudal, a genetic factor which affects the polarity of the embryo in Drosophila melanogaster
Authors: Bull Alice Louise 
Published: June 2005

AbstractAn inherited disturbance in egg polarity has been observed in Drosophila melanogaster. The bicaudal abnormal embryos develop the terminal segments of a second larval abdomen in mirror‐image symmetry to the terminal segments of the normal abdomen. The two abdomens may be symmetrical with four or five segments at each end of the egg or have more abdominal segments at the normal posterior end than at the reversed end. The reversed posterior ends appear to have normal spiracles, hindgut and Malpighian tubules. The bicaudal embryos and two other specific lethal types associated with them are produced in very low frequency. The production of these lethals is associated with an unmarked second chromosome, which has been carried in three separate inbred lines in combination with a Curly, Lobe, speck balancer chromosome. Flies homozygous for the chromosome and flies heterozygous for this chromosome and a second chromosome containing a deficiency at the vestigial locus can produce the syndrome. Reciprocal crosses, of flies of a genotype which can produce the syndrome with flies which do not, have shown that the maternal genotype is the controlling factor in the production of the abnormalities.
The regulation of alkaline phosphatase activity in the duodenum of the mouse from birth to maturity
Authors: Moog Florence 
Published: June 2005

AbstractActinomycin D elevates the alkaline phosphatase activity of the duodenum of the mouse. The effect is relatively slight, but positive, during the first postnatal week, but thereafter becomes marked, not only in the period before the normal maximal level of phosphatase activity is reached at 20 days, but also afterwards, as the activity declines to the adult level. The effect is not manifested in mice at the age of one month, but reappears in adults. Doses of actinomycin that enhance duodenal phosphatase activity depress the activity of the same enzyme in the kidney.Puromycin also increases duodenal phosphatase activity, the effect again being quite small in the first week. At all stages from nine days to adult, however, puromycin strongly elevates activity. Cycloheximide is also effective in raising duodenal phosphatase activity in young mice.Glucocorticoids are known to control the normal developmental increase of phosphatase, but the effect of actinomycin D can be exerted in adrenalectomized mice. The effects of both actinomycin and puromycin are additive with those of hydrocortisone acetate, and both raise phosphatase activity after 15 days, when exogenous corticoids no longer exert any influence.Puromycin stops mitosis in the duodenal epithelium in doses that elevate phosphatase. Hence, some alteration of the enzyme must occur in the striated border of cells that have emerged from the crypts and are in place on the surfaces of the villi. Since the phosphatase‐stimulating agents are all inhibitors of protein synthesis, the results are interpreted to mean that duodenal phosphatase normally tends to undergo an activity‐enhancing conversion that is restrained by a labile protein.
Electron microscopic studies of planaria. III. Some observations on the fine structure of planarian nervous tissue
Authors: Morita Michio , Best Jay Boyd 
Published: June 2005

AbstractThe small size of the nerve fibers of the planarian nervous system render the details of its neuroanatomy invisible to optical microscopy. Electron microscopic studies on the nervous system of Dugesia dorotocephala are described showing the neuropil of the brain, the origin of the ventral nerve cords from the brain neuropil, synaptic junctions in the neuropil, and “giant” fibers in the longitudinal conduction system. Two major kinds of synapses can be discerned as well as the pre‐ and post‐synaptic sides of each. There appear to be three major kinds of cells comprising the brain; neurons, neurosecretory cells, and neuroaccessory cells. The neurons are unmyelinated, contain neurotubules, and appear to synapse only in the centrally located neuropil.
Chemotaxis during fertilization in the hydroid Campanularia
Authors: Miller Richard L. 
Published: June 2005

AbstractThe pre‐fertilization behavior of the sperm of the thecate hydroids Campanularia flexuosa and Campanularia calceolifera has been observed and recorded by means of dark‐field cinephotomicrography. The sperm of both species activate and aggregate homotypically around the aperture of the female gonangium. Plots of the paths of sperm approaching the aperture show that the aggregations are the result of directed turning movements and not of so‐called trap‐actions or an increased random turning of the spermatozoa. An aperture‐associated tissue of ectoderm origin has been found to produce the attractive substances.Active sea water and alcohol extracts of female gonangia of C. calceolifera have been prepared. The substance affects sperm in the same ways as the material released by the female gonangium. The active material is heat stable, non‐volatile, dialyzable, polar, and appears to be a single molecular species of less than 5,000 mw. Injection of these extracts into sperm suspensions by means of a micropipette produces activation and aggregation of only the sperm of C. calceolifera about the pipette tip. If agar impregnated with the chemotactant is used as a source, the sperm are seen to orient with considerable accuracy. Extraction of C. flexuosa female gonangia has not yielded active extracts.These results demonstrate that chemotaxis does occur during fertilization in an animal. The mechanism of the reaction remains to be determined.
A variant of lactate dehydrogenase in somatic tissues of pigeons: Physicochemical properties and genetic control
Authors: Zinkham William H. , Kupchyk Luba , Blanco Antonio , Isensee Harriet 
Published: June 2005

AbstractThree genetic loci (a, b, and c) control lactate dehydrogenase synthesis in many mammalian and avian species. A survey of the lactate dehydrogenase isozyme composition of somatic tissues from approximately 1,000 wild pigeons revealed three phenotypic classes. The frequency distribution of the three classes in wild pigeons and the results of appropriate breeding experiments demonstrated that the phenotypic differences were due to alleles at the b‐locus. One of the alleles produces a B' polypeptide with an electrophoretic mobility identical to that of the A polypeptide, but with substrate affinity and heat inactivation properties similar to those of the B polypeptide.
Some comparative fine structure relationships of the rotifer integument
Authors: Koehler James K. 
Published: June 2005

AbstractSpecies representing three rotifer genera have been investigated with special emphasis on elucidating the detailed fine structure relationships of integumental derivatives. The classical concept of cuticulization in these animals must be modified to incorporate the finding that a genuine extracellular cuticle is lacking in a species thought to be very heavily cuticulized (loricate) namely, Keratella cochlearis. A consistent intracellular structural entity located just beneath the hypodermal plasma membrane is thought to represent the bulk of the reinforcing or exoskeletal material observed in all rotifers thus far examined. In Philodina, this “dense layer” is shown to be an insertion point for fiber tracts associated with muscle‐hypodermis desmosomes. The desmosomes are of interest in themselves since they are not of the septate type observed previously in rotifers and invertebrates in general, but are of the “standard” variety more commonly seen in higher animals.
Electrokinetic properties of dissociated chick embryo cells. I. Ph‐surface charge relationships and the effect of calcium ions
Authors: Collins Michael 
Published: June 2005

AbstractSince the electrokinetic properties of a particle depend entirely upon the particle's surface, microscopic electrophoresis of dissociated cells can yield information about the cellular surfaces. Dissociated heart ventricle and liver cells from five‐day chick embryos as well as neural retinal cells from seven‐day embryos have been examined electrophoretically over a wide pH range and the pH‐net surface charge density relation for each type of cell has been determined. Under the conditions selected the cells show differences with respect to these relations which appear to reflect differences in the molecular composition of the cells' surfaces.Since intercellular adhesion may occur through bivalent cation bridges with calcium being the cation most likely to be involved, the suppression of surface charge density by means of calcium ions at physiological concentration has been determined at physiological pH for heart ventricle, liver, neural retinal, and back epidermal cells. The degree of charge suppression, which varies among cells of different types, can be correlated with the apparent cellular adhesiveness as judged from sorting out behavior in some but not all cases.Dye exclusion, the ability of cells removed from the electrophoresis apparatus to reaggregate, and the reversibility of pH effects and calcium effects have been used to try to detect damage to the cells caused by experimental conditions. The results of these tests have seemed satisfactory.
Electrokinetic properties of dissociated chick embryo cells. II. Calcium ion binding by neural retinal cells
Authors: Collins Michael 
Published: June 2005

AbstractSince embryonic cells may be bound together by calcium ions forming bridges between negatively charged sites on the cellular surfaces, it is important to show that embryonic cells can bind calcium ions and to learn something of that binding. Neural retinal cells from seven‐day chick embryos have been dissociated and prepared for microscopic electrophoresis in three different ways. Their electrophoretic mobilities and surface charge densities have been determined over a range of calcium concentrations. The progressive reduction of charge density with increasing calcium concentration, with ionic strength held constant, clearly indicates calcium binding at the cellular surface.The data contained herein permit one to calculate a binding constant for the calcium‐binding site complex, the number of sites per cell surface, the average distance between them, the percentage of sites occupied by calcium ions at physiological calcium concentration, and the fraction of anionic sites on the cell surface which bind calcium. They also indicated that trypsin dissociation may remove calciumbinding material from cellular surfaces and suggest that that material may be regenerated during incubation in culture medium.
Tissue transplantation immunity in the adult newt, Diemictylus viridescens. I. The latent phase: Healing, restoration of circulation, and pigment cell changes in autografts and allografts
Authors: Cohen Nicholas 
Published: June 2005

AbstractFollowing the allogeneic transplantation of dorsal pigmented skin to the throat and flank of field collected adult Diemictylus viridescens there was, at 23 ± 0.5°C, a long latent period of about 16 days when such grafts were histologically and grossly indistinguishable from autografts.Circulation was usually restored in autografts and allografts between 10 and 11 days post‐grafting apparently by end to end anastomoses of graft and host vessels. Restoration of circulation was usually preceded by an initial dilation of the grafts' vessels and by the trauma induced death of some melanophores.An approximate five fold increase in the thickness of the dermal collagen of all grafts was noted throughout the latent phase as well as during graft rejection.
Parental influences on lactate dehydrogenase in the early development of hybrid frogs in the genus Rana
Authors: Wright David A. , Moyer Frank H. 
Published: June 2005

AbstractThe lactate dehydrogenase (LDH) isozymes of Rana pipiens pipiens, R. p. sphenocephala, and R. palustris were examined. LDH‐5 in all three organisms has the same electrophoretic mobility. There is a group of three to five bands in the LDH‐1 position which migrates fastest in R. pipiens sphenocephala, at an intermediate rate in R. pipiens, and slowest in R. palustris. Analysis of this multiple banding in the LDH‐1 position in R. pipiens suggests that these bands are distinct molecular forms. When the reciprocal crosses are made between frogs with different LDH patterns the maternal pattern persists in the embryo until stage 19 (heart beat) when hybrid and paternal bands first appear. The maternal contribution to the LDH pattern remains high, however, until stage 25 (feeding).In Rana sylvatica there are at least eighteen bands showing LDH activity. There are five bands in the LDH‐1 position, and the rest of the bands can be grouped into LDH‐2, LDH‐3, LDH‐4, and LDH‐5, all showing multiple bands. In the normal development of R. sylvatica there are marked shifts in the banding patterns in the LDH‐3, LDH‐4, and LDH‐5 groups between neurula and hatching, suggesting differential synthesis of the subunits forming these isozymes. In crosses between normal R. sylvatica females and a variant male which has additional bands in the LDH‐1 position, the paternal type bands appear after hatching.
Genetic analysis of three lactate dehydrogenase isozyme systems in trout: Evidence for linkage of genes coding subunits A and B
Authors: Morrison William J. , Wright James E. 
Published: June 2005

AbstractLactate dehydrogenase (LDH) isozymes of two genera within the family Salmonidae (Salvelinus and Salmo) were examined by acrylamide and starch gel electrophoresis. Those species examined contain three isozyme series involving five different kinds of subunits. The A‐B series, believed to be homologous to LDH 1–5 in the majority of vertebrates, is found in nearly all tissues. Polymorphism for subunit B was discovered in Salvelinus fontinalis in which two kinds, B and B', are present within a number of inbred strains. Various crosses and backcrosses involving S. fontinalis and Salvelinus namaycush demonstrate that subunits A and B are each coded by different autosomal genes (LA and LB). A limited amount of test‐cross data indicates linkage of these genes. Partial genetic analysis indicates that a second series of several LDH isozymes, largely restricted to the retina, involves a third subunit, C, in combination with B and to a lesser extent with A. A variant form of subunit C was found in Salmo trutta. Comparison of patterns of S. fontinalis and S. trutta and their hybrid seems to indicate that two additional subunits are involved in a third series of five isozymes found in the skeletal muscle of each species examined.
Nuclear activation at the onset of amphibian gastrulation
Authors: Bachvabova Rosemary , Davidson Eric H. 
Published: June 2005

AbstractA quantitative radioautographic study of RNA synthesis in the diverse cell types of the Xenopus blastula and gastrula is described. Nuclear activation, studied as increase in the number of grains in nuclear RNA after pulse‐labelling with uridine H3, was found to occur abruptly just before gastrular movements become observable. Presumptive endoderm and mesoderm participate in this widespread activation, while presumptive ectoderm becomes activated shortly after, at mid‐gastrulation. It is shown that per‐nucleus rates of high molecular weight, non‐ribosomal RNA synthesis increase at least 20 fold within one hour in endoderm and mesoderm as the embryo prepares to enter gastrulation.