bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of hexylene glycol and nocodazole on microtubules and melanosome translocation in melanophores of the medaka Oryzias latipes
Authors: Obika Masataka , Negishi Sumiko 
Published: June 2005

AbstractMelanophores of the medaka Oryzias latipes respond to the stimulation of alpha adrenergic receptors with a rapid centripetal translocation (aggregation) of melanosomes. Preincubation of isolated melanophores in hexylene glycol with or without colchicine results in an inhibition of melano‐some aggregation concomitantly with the disarrangement of the cytoplasmic microtubular framework. Incubation in hexylene glycol at higher concentrations induces structural modification and disassembly of preexisting microtubules, especially in the perinuclear region of the cells. A microtubule inhibitor, nocodazole, also inhibits melanosome aggregation through disruption of micro‐tubules. These results indicate that both the presence of a substantial number of microtubules and their innate arrangement are indispensable for the rapid centripetal translocation of melanosomes. The results also suggest that micro‐tubules undergo cycles of disassembly and reassembly during pigment movement.
Absence of DNA in yolk platelets of Bufo arenarum oocytes
Authors: de Recondo Marta E. Fernández , de Arcuri Beatriz Fernández , Recondo Eduardo F. 
Published: June 2005

AbstractThe absence of DNA in the yolk platelets of Bufo arenarum oocytes was verified. Oocytes from the coelomic cavity were used in order to avoid possible contamination by the ovarian tissue. Four methods for DNA analysis were employed, and the possibility of interference was carefully checked. The presence of three possible contaminants, which produced positive reactions from the DNA analysis, was detected. These were the glycosaminoglycan from the superficial layer of the platelets, sucrose, and polyvinylpyrrolidone from the buffer commonly used during the isolation of platelets.The present evidence points to the necessity of using at least two different methods for DNA determination with due regard for their sensitivity and specificity before any firm conclusion can be reached on the presence or absence of DNA in nonnuclear and mitochondrial parts of the oocyte.
Electron microscopic analysis of the sperm nuclear changes in meiosis inhibited eggs of the brittle‐star Amphipholis kochii
Authors: Yamashita Masakane 
Published: June 2005

AbstractThis paper describes the sperm nuclear changes in the eggs of the brittle‐star Amphipholis kochii that had been treated with meiosis inhibitors, including the nuclear division inhibitors (colchicine, colcemid, griseofulvin, and vinblastine) and the cytokinesis inhibitor (cytochalasin B), as observed by transmission electron microscopy. In the normal, monospermic fertilization process, the male pronucleus formation consists of two processes: the first dispersion process before formation of the nuclear envelope and the second dispersion process on and after envelope formation. When nuclear division was inhibited, so that the female pronucleus formation was also inhibited, the sperm nucleus incorporated into such eggs decondensed to some extent, in accordance with the first dispersion process, but the nuclear envelope did not form around the nucleus and further decondensation (the second dispersion process) was also inhibited. When cytokinesis was inhibited, the sperm nucleus, as well as the maternal chromosomes, transformed into the pronuclei on schedule. These results suggest that 1) the male pronucleus formation has an intimate relationship with meiosis, especially nuclear division, as well as with the formation of the female pronucleus; 2) the male pronucleus formation consists of at least two different processes, a meiosis‐independent process (the first dispersion process) and a meiosis‐dependent process (the second dispersion process); and 3) the factor for the first dispersion process is a soluble component while the factor for the second dispersion process is membrane associated.
Chicken developmental antigens: Analysis of erythroid populations with monoclonal antibodies
Authors: Trembicki K. A. , Dietert R. R. 
Published: June 2005

AbstractFusions were performed between the mouse PAI myeloma cell line and spleen cells from Balb/c mice immunized with intact erythrocytes from 1‐day Cornell K‐strain White Leghorn chickens. Following single cell cloning, four hybridoma clones were found to secrete erythroid specific monoclonal antibodies. Based on its pattern of reactivity, the antibody (IgG2a, κ) secreted by clone 10C6 detects a specific avian oncodevelopmental antigen associated with the hematopoietic system: chicken fetal antigen (CFa). Two other clones, designated as 3F12 and 4C2, produced antibodies (IgM, κ) that recognize another avian developmental antigen: chicken adult antigen (CAa). A fourth clone, 9F9, produced an antibody (IgM, κ) that reacts with all peripheral erythrocytes from both Japanese quail and chicken regardless of age. Clone 10C6 antibody apparently detects an erythrocyte specific (ES) determinant of CFA associated with determinant #8 while antibodies of clones 3F12 and 4C2 recognize a chicken specific determinant of CAA. Analysis by complement mediated microcytotoxicity indicated that the epitopes detected by 10C6 vs 3F12 and 4C2 antibodies were expressed on erythrocytes in a reciprocal fashion during development. Furthermore, strain variations in the incidence of erythrocytes carrying these epitopes were observed. The usefulness of these monoclonal antibodies for the study of erythroid populations is discussed.
Nerve repair and behavioral recovery following brain transplantation in Notoplana acticola, a polyclad flatworm
Authors: Davies Lynnae , Keenan Larry , Koopowitz Harold 
Published: June 2005

AbstractAlthough Notoplana acticola, a marine polyclad, cannot regenerate brain tissue, neuronal repair is rapid. Brains were transplanted into decerebrate flatworms to determine the anatomical patterns and functionality of neural connections established between a new brain and the peripheral nerve network of the recipient animal. Sixty‐nine transplants were performed. Four brain transplant orientations were used: normal, reversed, inverted, and reversed inverted. The functionality of the transplanted brains was tested and measured using both behavioral and electrophysiological criteria. Within 23 days, 56% of the transplants that survived and retained the transplants recovered the four behaviors tested: righting behavior, avoidance turning, ditaxic locomotion, and feeding. Nerves exiting the brain tended to join with the peripheral nerves closest to them. Anatomical connections were made within 24 hr of surgery. Some normal behavior was seen within the first 36 hrs after surgery. Control decerebrate worms did not recover behavior. Preliminary intracellular recordings from three types of identified brain sensory interneurons, in transplants, revealed normal electrophysiological properties and this implied that appropriate connections with peripheral sensory cells had been reestablished. Intracellular dye‐marking of these neurons in reverse‐oriented brains revealed that, although individual nerve processes apparently leave the brain and associate with inappropriate nerve cords, some of the processes turn 180° to reinervate nerve cords, which they normally occupy in unoperated animals. Thus, although anatomical and functional neural connections apparently were made rapidly following brain transplantation, the specificity of the reconnections remains to be shown.
Plasma and pituitary prolactin levels in rainbow trout during adaptation to different salinities
Authors: Prunet P. , Boeuf G. , Houdebine L. M. 
Published: June 2005

AbstractThe development of a highly specific radioimmunoassay for salmonid prolactin (PRL) using chinook salmon PRL allowed us to study plasma and pituitary PRL profiles in large sedentary rainbow trout (Salmo gairdneri) transferred from fresh water to seawater and vice versa. Plasma osmotic pressure and chloride levels were also measured for 3 weeks following change of salinity. Within 1 day after transfer to full seawater we observed a plasma PRL decrease, which stayed significantly lower (3–5 ng/ml) than the fresh water control group (10–15 ng/ml) during the entire experiment. Pituitary PRL content showed an initial abrupt increase, but after 3 weeks in seawater pituitary PRL content had decreased to the same level as in the fresh water control group. On the contrary, transfer from seawater to fresh water was followed within 1 day by a rise in plasma PRL levels, which stayed high (10–15 ng/ml) after 3 weeks in fresh water. Simultaneously, pituitary PRL content decreased significantly. These results may indicate an important role of PRL in fresh water adaptation of sedentary rainbow trout.
Studies on the mechanisms of neurulation in the chick: Interrelationship of contractile proteins, microfilaments, and the shape of neuroepithelial cells
Authors: Lee Hsin‐Yi , Nagele Robert G. 
Published: June 2005

AbstractElectron microscopy and indirect immunofluorescence were employed to correlate the distribution patterns of major contractile proteins (actin and myosin) with 1) the organizational state of microfilaments, 2) the apical cell surface topography, 3) the shape of the neuroepithelial cells, and 4) the degree of bending of the neuroepithelium during neurulation in chick embryos at Hamburger and Hamilton stages 5–10 of development. Both actin and myosin are present at these developmental stages and colocalize in the neural plate as well as in later phases of neurulation. During elevation of neural folds, actin‐ and myosin‐specific fluorescence is always most intense in regions where the greatest degree of bending of the neuroepithelium takes place [e.g., the midline of the V‐shaped neuroepithelium (early neural fold stage) and the midlateral walls of the “C”‐shaped neuroepithelium (mid–neural‐fold stage)]. This intense fluorescence coincides with 1) a particularly dense packing of microfilaments and 2) highly constricted cell apices. After neural folds make contact, there is an overall reduction in both the intensity of apical fluorescence and the thickness of apical microfilament bundles, especially in the roof and floor of the neural tube. The remaining fluorescence in the contact area is apparently related to cellular movements during fusion of neural folds.
Association of maternal and newly synthesized ribosomes with membranous noncytoskeletal structures in Xenopus laevis embryonic cells
Authors: Shiokawa Koichiro , Tashiro Kosuke , Misumi Yoshio 
Published: June 2005

AbstractIn Xenopus laevis embryos a high concentration of both KCl and 0.5% DOC (sodium deoxycholate) is needed for maximal extraction of ribosomes and polysomes. We studied the nature of the structures that keep ribosomes and polysomes immobilized within the cytoplasm of embryonic cells at cleavage through tailbud stages, using various combinations of a low‐salt buffer (20 mM KCl), a high‐salt buffer (500 mM KCl), 0.5% DOC, and 0.5% Triton X‐100. With a low‐salt buffer and 0.5% DOC, but not Triton X‐100, 80S ribosomal monomers and polysomes were liberated from the cytoplasmic rapidly sedimenting structures (RSS) to the soluble fraction. With a high‐salt buffer (500 mM KCl), ribosomes were solubilized as 60S and 40S subunits together with about one‐half of the total polysomes. When cells were homogenized in a low‐salt buffer with added inhibitors of the cytoskeleton (cytochalasin B or colchicine), the majority of polysomes but not ribosomes were solubilized. These results provide evidence for the following conclusions. 1) Polysomes are bound to cytoskeletal structures in Xenopus embryos, but ribosomes, both maternal and newly synthesized, are associated with membranous noncytoskeletal structures. 2) The membranous structures consist of two compartments, one high‐salt sensitive and the other high‐salt resistant. 3) Ribosomes of the high‐salt resistant group increase in amount with developmental stage and appear to be the precursor to the ribosomes of the high‐salt sensitive group.
Inhibition of DNA replication in preimplantation mouse embryos by aphidicolin
Authors: Spindle Akiko , Nagano Hiroshi , Pedersen Roger A. 
Published: June 2005

AbstractThe regulation of trophectoderm differentiation in mouse embryos was studied by inhibiting DNA synthesis with aphidicolin, a specific inhibitor of DNA polymerase alpha. Embryos were exposed to aphidicolin (0.5μg/ml) for 16 h at various preimplantation stages and scored for their ability to form a blastocyst and develop beyond the blastocyst stage. Embryos were most sensitive to aphidicolin at the late 4‐cell stage and became progressively less sensitive as they developed. Aphidicolin inhibited blastocyst formation by 70%, 100%, 77%, and 24% after treatment at the 2‐cell, 4‐cell, noncompacted 8‐cell, and compacted 8‐cell stages, respectively. Although the inhibitory effect of aphidicolin on blastocyst formation decreased markedly as 8‐cell embryos underwent compaction, developmental capacity beyond the blastocyst stage was poor after treatment of either noncompacted or compacted 8‐cell embryos. Treatment at the morula and early blastocyst stages was less harmful to embryos than treatment at earlier stages but reduced the number of trophoblast outgrowths by interfering with hatching. Autoradiographic analysis showed that during aphidicolin treatment, incorporation of 3H‐thymidine was inhibited over 90% at all stages examined, indicating an inhibition of DNA synthesis. Because inhibition of blastocyst formation by aphidicolin decreased at the compacted 8‐cell stage, we suggest that approximately the first half of the fourth DNA replication cycle is critical for subsequent blastocyst formation. Furthermore, the poor further development of blastocysts formed after aphidicolin treatment of compacted 8‐cell embryos suggests that the DNA replication requirements for initial trophectoderm differentiation are distinct from requirements for further development of blastocysts in vitro.
Cytotoxic rejection of xenografts between marine sponges
Authors: Buscema Marco , Van de Vyver Gyséle 
Published: June 2005

AbstractIn order to extend the range of investigations on sponge incompatibility reactions, xenografts were performed underwater between three marine species: the ramose sponge Axinella polypoides and the two encrusting sponges Crambe crambe and Hemimycale columella. The rejection processes were followed using light, transmission electron, and scanning electron microscopy. In both combinations observed—Axinella/Crambe and Axinella/Hemimycale—the xenografts show disorganization of the superficial tissues during the first days of contact and development afterward of a necrotic reaction. The rejection process is characterized by 1) rapidity, strength, and reciprocity of reaction; 2) tissue necrosis of great depth; and 3) restriction of the response to the zone of the contact. Control of reaction specificity was achieved by contact of sponges with some inert materials (PVC foam, glass, cork, and granite). This resulted in various nonnecrotic reactions. The diversity of these reactions, together with the xenograft rejection processes, demonstrates new aspects of discriminative sponge capabilities. Alternative explanations of acute xenograft rejection, involving either killer cells or cytotoxic substances from endogenous or exogenous origin, are discussed.
The distribution of actin in sheep ovaries
Authors: Cran David G. , Musk Linda 
Published: June 2005

AbstractThe distribution of actin in sheep ovaries has been examined using immunofluorescent techniques. The germinal epithelium, which contained abundant microfibrils, fluoresced strongly while the underlying stroma was only weakly positive. During early follicular growth a band of fluorescence was associated with the base of those granulosa cells abutting onto the basal lamina. This transitional polarity of actin distribution was correlated with cell shape changes in the basal granulosa.
Isolation and enzymatic characterization of the plasmalemma from bovine spermatozoa
Authors: Casali E. , Farruggia G. , Spisni A. , Pasquali‐Ronchetti I. , Masotti L. 
Published: June 2005

AbstractAn improved method for the isolation of pure plasma and acrosomal membranes from bull spermatozoa is presented. Plasma membranes were isolated from the spermatozoa of bulls of different breeds, and some enzymatic activity, such as (Na+‐K+) ATPase, Ca++ ATPase, Mg++ ATPase, alkaline and acidic phosphatases were assayed. Such enzymatic activity levels differ noticeably from those published by other authors, whose preparations were probably contaminated by other cellular components. Highly statistically significant differences of these activities have been found among the several breeds.
Cell‐free translation of Drosophila imaginal disc mRNA
Authors: Greenberg Robert M. , Adler Paul N. 
Published: June 2005

AbstractTotal RNA derived from the imaginal discs of Drosophila melanogaster was translated in vitro, and the polypeptide products electrophoresed on two‐dimensional gels. In agreement with previously published examinations of imaginal disc protein synthesis and content, we can detect no reproducible differences in abundant mRNA populations between different disc types (foreleg and wing). Differences can be found, however, between imaginal discs and other tissues. We also present evidence for a nonuniformly distributed wing disc mRNA.
Retention of lateral motor column neurons during the phase of rapid cell loss after limb amputation in Rana pipiens tadpoles
Authors: Kett Nancy A. , Pollack Emanuel D. 
Published: June 2005

AbstractTarget tissue regulation of naturally occurring neuronal death during development has often been studied by removing a limb bud and then analyzing spinal motor neuron number later in development. The present study focuses on the necessity for limb presence in the initiation of the most rapid phase of cell loss from the lateral motor column (LMC) and in the control of neuron number during this restricted developmental period. Unilateral hindlimb amputation in larval Rana pipiens at the time of onset of rapid LMC cell loss resulted in an unequal, bilateral retention of excess motor neurons (i.e., less cell loss than normally occurs) during this phase. Limb traumatization, with axotomy, also resulted in reduced bilateral LMC cell loss, although to a lesser extent than did amputation. Absence of the limb or axonal transection presumably prevents the communication of motor neurons with their differentiating targets and thus interferes with the flow of information required for the selective events of neuronal loss and survival. The presence of the limb with intact axons is essential at the time that LMC cell loss normally ensues for both the initiation and progression of the phase of greatest cell loss.
Sperm motility in the horseshoe crab. V: Zinc removal mediates chelator initiation of motility
Authors: Clapper David L. , Lamothe Paul J. , Davis James A. , Epel David 
Published: June 2005

AbstractLimulus spermatozoa are nonmotile after dilution into sea water, and motility is initiated in situ by a sperm motility‐initiating peptide (SMI) that emanates from Limulus eggs. In the absence of SMI, several structurally different chelators (EDTA, EGTA, phenanthroline, dipyridyl, cysteine, and dithiothreitol; 1 mM each) initiated sperm motility; and in the presence of SMI, EDTA prolonged the duration of motility initiated by SMI. Of the elements determined to be present in Limulus sperm, Zn+2 (0.1 μM free Zn+2) was both the most effective at preventing EDTA initiation of motility and the only ion to prevent EDTA prolongation of SMI‐initiated motility. 65Zn was concentrated from sea water by Limulus sperm and was rapidly removed by EDTA. These results indicate that removal of the Zn+2 normally associated with Limulus spermatozoa can initiate or enhance motility. However, SMI does not act as a Zn+2 chelator, since SMI removed little 65Zn from the sperm while at the same time initiating motility of greater percentage and duration than did EDTA. The mechanism by which Zn+2 removal enhances sperm motility is not yet known but could involve a Zn+2‐dependent or Zn+2‐regulated step in the pathway of SMI action.
Characterization of molt‐inhibiting hormone (MIH) action on crustacean Y‐organ segments and dispersed cells in culture and a bioassay for MIH activity
Authors: Mattson Mark P. , Spaziani Eugene 
Published: June 2005

AbstractEcdysteroid secretion in vitro by gland quarters and dispersed cells of ecdysial glands (Y‐organs) of the crab, Cancer antennarius Stimpson, was characterized. Optimum culture conditions are reported for maximum, sustained (72 hr) secretion and maintenance of cell viability in activated Y‐organs obtained from de‐eyestalked donors. Addition in vitro of eyestalk ganglia extracts containing the putative molt‐inhibiting hormone (MIH) inhibited ecdysteroid production dose‐dependently in the range of 0.1–4.0 and 0.01–4.0 eyestalk equivalents of MIH for gland quarters and dispersed cells, respectively. Inhibition by MIH was reversible, tissue specific as to source of MIH activity, and did not affect cell viability relative to controls. The results of replicate incubations of gland quarters with MIH were analyzed with formal statistics of parallel‐line assay. The inhibitory action on ecdysteroid secretion is shown to be reproducibly linear and parallel in the dosage range, 0.1–4.0 eyestalk equivalents, amenable to calculation of relative potency among successive extracts, and of sufficiently high precision to serve as an MIH bioassay. Also, the results of these studies support the hypothesis that control of Y‐organs by the eyestalks is physiologically direct.
Calcium from extracellular concretions in the gills of freshwater unionid mussels is mobilized during reproduction
Authors: Silverman Harold , Steffens W. L. , Dietz Thomas H. 
Published: June 2005

AbstractAt least 20–60% of the dry weight of unionid gills occurs as inorganic calcium concretions. These concretions are a calcium store mobilized during reproduction. The concretion content in gills of reproductively active animals decreases, as determined by morphological study and chemical isolation. While mobilization is occurring, maternal blood phosphate and bicarbonate remain normal, and calcium declines. These data are consistent with the hypothesis that concretion calcium, from the gills, leaves the maternal animal and may serve as a calcium source for glochidial shell formation in the calcium poor freshwater environment.
Changes in protein synthesis during early cleavage of the Mongolian gerbil embryo
Authors: Norris Michael L. , Barton Sheila C. , Surani M. Azim H. 
Published: June 2005

AbstractAn examination of polypeptide synthesis during early development in the Mongolian gerbil revealed similar protein profiles up to the early 2‐cell stage, and a gradual change over a period of ∼18 h to give a distinctly different profile by the late 2‐cell stage which remained largely unchanged thereafter. The incorporation of [35S] methionine into protein was significantly reduced by the late 2‐cell stage, followed by a marked increase 24 h later. Enucleation of fertilized 1‐cell embryos and culture in vitro resulted in retention of the early 2‐cell profile. These results indicate probable transition from the initial use of stored maternal message before the onset of embryonic gene activity. Comparisons have been made with similar studies in the mouse.