bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uncoordinated synthesis of histones and DNA by mouse eggs and preimplantation embryos
Authors: Kaye Peter L. , Church Robert B. 
Published: June 2005

AbstractThe temporal coordination of histone and DNA synthesis in mouse eggs and preimplantation embryos were examined. In unfertilized mouse eggs arrested at metaphase II, histone synthesis was observed, but at lower rates than previously reported for fertilized zygotes. Cytosine arabinoside, an inhibitor of DNA synthesis, was used to study the relationship between DNA and histone synthesis during cleavage stages of mouse development. Cytosine arabinoside (50 μM) inhibited by 90% the incorporation of [3H]thymidine into DNA by two‐cell embryos and blastocysts. At this concentration, cytosine arabinoside inhibited incorporation of [3H] lysine into blastocyst histones by only 30% and had no effect at the two‐cell stage. These results are interpreted to show that DNA synthesis and histone synthesis are not coordinated temporally during early development of the mouse, but may become more so as development proceeds.
Medroxyprogesterone, immunosuppression, and conceptus size in Peromyscus
Authors: Bell Floyd E. , Palmer Jennifer S. , Dawson Wallace D. 
Published: June 2005

AbstractEffects of exogenous medroxyprogesterone acetate (MPA) on skin transplant retention and conceptus size were studied in the deer mouse, Peromyscus maniculatus, and the oldfield mouse Peromyscus polionotus. Daily injections of 2 mg MPA significantly prolonged survival of allografts in P. maniculatus and transspecific grafts between P. maniculatus and P. polionotus. Allografts were retained significantly longer than transspecific grafts (17.2 vs 12.4 days) on MPA‐treated P. maniculatus. Near‐term fetal and placental sizes and weights were not detectably influenced by daily 1‐mg MPA injections given to the mother from the 5th through the 19th day of pregnancy. The data are discussed relative to the possible immunosuppressive role of progestins in protecting the allogeneic conceptus from maternal immune rejection.
Sodium ion concentrations in uterine flushings from “implanting” and “delayed implanting” mice
Authors: Van Winkle Lon J. , Campione Allan L. , Webster Douglas P. 
Published: June 2005

AbstractThe uteri of mice were flushed with isotonic marnnitol (1) on the day of implantation during normal pregnancy or (2) during delay of implantation. The Na+ concentration in flushings was reduced during diapause but had increased by 65% 24 h after progesterone‐treated ovariectomized mice received estrogen injections. The results suggest that the apparent metabolic quiescence of diapausing blastocysts may, in part, be a consequence of lower (Na+) in the uterus during delay of implantation.
Cellular aspects of allograft rejection in marine sponges of the genus Polymastia
Authors: Van de Vyver Gysèle , Barbieux Bruno 
Published: June 2005

AbstractAllograft rejection processes of two taxonomically related sponge species, Polymastia robusta and Polymastia mamillaris, have been studied at the cellular level. Grafts in parabiosis have been made by pairing papillae. They were investigated using histology and scanning and transmission electron microscopy.In Polymatia robusta, allografts undergo progressive rejection with adhesion. A few days after grafting, archaeocytes and collencytes migrate toward the zone of contact and fall into line on either side of this zone. The narrow space which separates the grafted papillae is progressively filled up with collagen fibers thanks to which the parabionts are firmly held together. Allografts of Polymastia mamillaris never fuse to each other; the specimens are completely and directly rejected. In this species, the cell migration to the zone of contact is not followed by their alignment nor by deposition of a collagen layer. Autografts made in similar conditions succeed in all cases in both species.These experiments demonstrate for the first time that sponges, even taxonomically closely related, may develop different but defined processes of rejection.
Adaptations for reflection of bioluminescent light in the gas bladder of Leiognathus equulus (perciformes: Leiognathidae)
Authors: McFall‐Ngai Margaret J. 
Published: June 2005

AbstractThe gas bladder of leiognathid fishes functions not only in buoyancy but also in reflection of bioluminescent light from the circumesophageal light organ. Purine distribution, quality (guanine/hypoxanthine ratio), and concentration, as the basis for reflectivity, were assayed enzymatically for different portions of the gas bladder lining of the common leiognathid, Leiognathus equulus (Forskal). For highly reflective areas, the percentage of tissue wet mass and dry mass represented by purine was also determined. The results indicate that total purine content in the reflective areas of the leiognathid bladder was significantly higher than values determined for other similar, shallow water fishes; instead, purine content in these reflective areas was similar to that known for very deep‐dwelling fishes, in which heavy purine deposition is correlated with high pressures and high oxygen concentrations in the bladder. In addition, the results show that differential purine distribution within the bladder correlates strikingly with the path of bioluminescent light. The dorsal bladder lining, the primary site of incident luminescence, had extremely high purine concentrations (averaging 2.80 mg/cm2), whereas the secondary reflective surfaces, the lateral (1.81 mg/cm2) and ventral (1.22 mg/ cm2) portions, although high in purine content, had concentrations significantly lower than the dorsum. Areas through which light is transmitted, the light organ‐bladder interface (0.09 mg/cm2) and the posterior region (0.19 mg/ cm2), were greatly reduced in purine content. The enhancement of purine in the reflective portions of the bladder and the correlation of the differential distribution of purines with the path of light indicate that the L. equulus gas bladder is exquisitely adapted to function as a reflector of bioluminescent light.
Immediate and delayed effects of vincristine administered during early postimplantation stages of murine embryogenesis
Authors: Wan Yu‐Jui , Wu Tsung‐Chieh , Damjanov Ivan 
Published: June 2005

AbstractVincristine was given to pregnant mice on day 7½ of pregnancy and the teratogenic effects of this treatment were assessed 2 and 3 days thereafter. Most of the embryos in litters removed on day 9½ of pregnancy (2 days after treatment) were morphologically normal, whereas on day 10½ most embryos were either developmentally retarded by the treatment or malformed. The morphologically “normal” embryos removed on day 9½ of pregnancy were cultured in vitro for 24 h. During this procedure more than 50% of them showed growth retardation or abnormal development. These data indicate that exposure of early postimplantation embryos to vincristine has an immediate teratogenic and embryocidal action, and also a delayed effect which becomes apparent only several days after exposure and following an ostensibly “normal” period of embryonic development.
Dynamics of pigment pattern formation in the zebrafish, Brachydanio rerio. III. Effect of anteroposterior location of three‐day lateral line melanophores on colonization by the second wave of melanophores
Authors: Milos Nadine , Dingle Allan D. , Milos Joseph P. 
Published: June 2005

AbstractThe mode of colonization of the lateral line melanophore band of the zebrafish, Brachydanio rerio, by the second wave of melanophores has been investigated. This stripe forms in two consecutive stages. First, there is an initial migration and reorientation of pigment cells in an anteroposterior wave into the site to form an interrupted stripe. Following this, a round of melanophores differentiates directly at the site and fills in the gaps between the initial cells. An analysis of the distributions of initial and second wave melanophores along the stripe site has shown that both groups of cells are selective as to localization. Initial wave melanophores colonize more anterior somite areas than do second wave melanophores. However, both groups of cells exhibit preferential colonization of the same anterior sites. It is suggested that second wave melanophores attempt to colonize the same somite areas of the stripe as the initial wave of melanophores but are forced to move to more posterior locations due to the presence of initial wave melanophores anteriorly. Observations were also made on later stages of development of the lateral line melanophore band. These melanophores retain the ability to migrate. Some of them reorient out onto the flank and contribute to the juvenile flank pigment pattern.
Correlation of increased intraacrosomal pH with the hamster sperm acrosome reaction
Authors: Working Peter K. , Meizel Stanley 
Published: June 2005

AbstractThis study describes investigations of the importance of intraacrosomal pH in the hamster sperm acrosome reaction (AR). Washed cauda epididymal sperm were capacitated in vitro in a medium containing 2 mM Ca2+, 144 mM Na +, and 3 mM K +. Such sperm underwent a significant increase in the number of AR within 10 min after the addition of the Mg2+ −ATPase (adenosine triphosphatase) inhibitors DCCD (20,μM) or NBD‐Cl (10 μM) or the proton ionophore FCCP (6 μg/ml) at 3.5 hr of incubation or after addition of NH4Cl (3 mM) at 4 hr of incubation. Addition of the mitochondrial electron transport inhibitor rotenone (2.5 μM) at 3.5 hr or of NaCl (3 mM) or KCl (3 mM) at 4 hr did not stimulate AR over control levels, suggesting that the stimulation of AR by the other compounds was not directly due to depletion of acrosomal adenosine triphosphate (ATP) or alteration of the acrosomal transmembrane potential. The AR also was not stimulated by either DCCD or FCCP added prior to 3 hr of incubation of sperm, whereas both compounds were increasingly effective at stimulating AR with increasing length of preincubation of sperm before the addition of the test compounds.The intraacrosomal pH of sperm incubated in low [K+] (0.6–0.9 mM) for 3.5 hr rose by at least one pH unit (as measured with the fluorescent dye 9‐aminoacridine) within 15–30 min after raising extracellular [K + ] to 4.2–4.5 mM. The pH rise occurred even in the presence of the Ca2+‐chelator EGTA (2 mM). Either FCCP (8μg/ml) or DCCD (20 μM), but not rotenone (2.5 μM), plus K+ (3.6 mM), raised the intraacrosomal pH of sperm incubated for 3 hr in low [K+] within 10 min after addition. No pH rise occurred in the absence of additional K +.These results demonstrate that the intraacrosomal pH of the hamster sperm becomes more alkaline in a process not requiring high concentrations of external Ca2+, but requiring K +. The results of this and previous studies lead us to suggest here that the intraacrosomal pH rise may be mediated via a change in K+ and H+ permeability of sperm head membranes, which allows K+ influx and H+ efflux, and via inhibition of an acrosomal Mg2+ −ATPase proton pump. We propose that the permeability changes and the consequent alkalinization of the acrosomal interior are important steps in late capacitation and/or the mammalian AR.
Cytokinesis: Furrowing activity in nucleated endoplasmic fragments of fertilized sand dollar eggs
Authors: Rappaport R. 
Published: June 2005

AbstractWhen the sand dollar egg surface is extensively disrupted by contact with an expanding oil drop, and the egg contents are squeezed out by mechanical pressure, the denuded endoplasm is rapidly covered by a new surface. The original egg surface alters its appearance as the area that it covers diminishes, and the original and the new surfaces become different in appearance and behavior. If a mitotic apparatus is pushed into the endoplasmic fragment, the fragment surface undergoes furrowing activity, which is synchronous with typical cyclical changes in the appearance of the mitotic apparatus. In this circumstance, furrows develop later and progress more slowly than normal. Furrows formed soon after the operation usually regress, but those developing in conjunction with subsequent cell cycles are more nearly normal and are frequently permanent.
Preliminary investigations on the possible antimicrobial properties of tunicate blood cell vanadium
Authors: Rowley Andrew F. 
Published: June 2005

AbstractTunicates have the unique ability to accumulate and store metals such as vanadium. In the sea squirt, Ciona intestinalis, this element is stored in phagocytic blood cells termed granular amoebocytes and vacuolar hyaline amoebocytes. Incubation of bacteria and amoebocytes together results in the phagocytosis of these particles with subsequent fusion of the vanadium‐containing vaeuoles with the bacteria‐laden phagosomes. This process may be important in the intracellular digestion of such microorganisms.
Acid‐base balance and Na+ regulation in rainbow trout during exposure to, and recovery from, low environmental pH
Authors: Holeton G. F. , Booth J. H. , Jansz G. F. 
Published: June 2005

AbstractRainbow trout in simulated hard water were exposed to pH 4 for 4 days, followed by 3 days at pH 7, to evaluate both the effects of lowered water pH on the mechanisms of acid‐base balance and iono‐regulation, and the ability of the fish to recover from the pathophysiological consequences of this form of acid stress. Prior to the acid stress, the fish maintained a relatively constant internal acid‐base balance. Na+ was absorbed from the surrounding water. At pH 4 a net uptake of H+ ions from the water resulted in acidaemia combined with a significant reduction in plasma [HCO3−]. Plasma [Na+] increased for the first 24 hours of acid exposure before falling to levels significantly lower than the preacidification values. Hematocrit remained above the preacidification levels throughout the period of acid stress. Upon returning to pH 7 the normal acid‐base status was restored within 24 hours. Na+ was absorbed from the water, and plasma [Na+] returned almost to control levels within 24 hours. Hematocrit fell rapidly and remained depressed throughout the 3‐day recovery period. The results suggest that the physiological effects of short‐term exposure to low water pH are probably entirely reversible.
Entrainment of daily serum gonadotropin cycles in the goldfish to photoperiod, feeding, and daily thermocycles
Authors: Hontela Alice , Peter Richard E. 
Published: June 2005

AbstractFemale fish were kept under 16L:8D/20°C in November and April and the onset of light and/or feeding times were shifted by several hours in the experimental groups. Photoperiod and feeding entrained significant fluctuations in serum gonadotropin hormone (GTH) levels when the onset of light and the first daily feeding were 4 hr apart, but not when they were 10 hr apart. Fish were subjected to 16L:8D for 14–16 days in February, and to either a constant warm (20°C) or a diurnal sinusoidal (12–20°C) temperature regime, the warmth being imposed during photophase or scotophase. While relatively high, uniform serum GTH levels were found throughout the 24‐hr period in fish subjected to constant warmth, warm temperature during the day promoted fluctuations in serum GTH levels, and warmth during night resulted in relatively low, uniform serum GTH levels.
Immunohistochemical localization of laminin within the mouse ovary
Authors: Wordinger Robert J. , Rudick Victoria L. , Rudick Michael J. 
Published: June 2005

AbstractLaminin, a noncollagenous glycoprotein, was observed in the mouse ovary using a direct immunofluorescence technique. Laminin was localized within the basal lamina underlying growing and atretic ovarian follicles, blood vessels, and the germinal epithelium. In addition, laminin was also present at the periphery of individual corpora lutea cells. The presence of laminin in the basal lamina underlying ovarian follicles may be important for the passage of material between the follicle cells and the connective tissue stroma. In addition, its location around the corpora lutea cells may reflect an involvement in cell to cell contact as well as intercellular communication.
Precocious hatching of Ilyanassa obsoleta embryos exposed to CaCl2 or KCl1
Authors: Sullivan Charles H. 
Published: June 2005

AbstractIlyanassa obsoleta embryos are enclosed within a maternally produced capsule until hatching around day 8 of development. Hatching occurs when a chemical hatching substance is released from embryos that dissolves the capsule plug, providing a means of escape for the embryos. The activity of the hatching substance can be detected in homogenates of prehatching embryos and its release can be rapidly triggered by incubating prehatching capsules in solutions of CaCl2 or KCl. With both homogenization and cationinduced release, hatching activity has been detected in embryos as early as day 5, 2 days before the onset of significant hatching. Therefore, the hatching substance is synthesized in advance of hatching, with release, rather than synthesis, being the controlling step in the hatching process.
Nuclear kinetics during cleavage in a dipteran egg
Authors: Lundquist Anders , Löwkvist Bertil 
Published: June 2005

AbstractThe numbers of intravitelline and periplasmic nuclei have been determined throughout pregastrular development in the Calliphora egg. The intravitelline nuclear divisions are synchronous and the peripheral divisions are parasynchronous. In spite of this, the total number of nuclei is lower than 2n from the middle part of intravitelline cleavage and onward. This is probably caused mainly by loss of nuclei during midintravitelline cleavage. Proportionally less important losses may occur during subsequent stages. The vitellophage nuclei are secondarily derived. Most of them are formed by the migration of nuclei from all regions of the syncytial blastoderm. This migration takes place mainly during the early part of the interphase following after the completion of the nuclear divisions. Vitellophage formation, the primary somatic differentiation process, is thus radically different in Calliphora and Drosophila. As a consequence, the total number of nuclei is higher just before gastrulation in the Calliphora egg.
Fertilization of mammalian eggs by sperm injection
Authors: Markert Clement L. 
Published: June 2005

AbstractMammalian sperm normally fertilize eggs in the ampulla of the oviduct after a long trip through the female reproductive tract. During this trip, the sperm become capacitated to fertilize but must overcome substantial barriers in the form of egg investments before reaching the plasma membrane of the egg. Once inside the egg the head of the sperm responds to cytoplasmic factors to decondense and form a pronucleus. All the problems of sperm penetration of the egg and its investments can be circumvented by injecting the sperm into the egg with a micropipette. Such injected sperm can participate normally in the subsequent events, typical of fertilized eggs, that lead to the formation of embryos. Sperm can also be injected into normally fertilized eggs to produce a third pronucleus and a triploid embryo.To avoid the mechanical problems of capturing a swimming sperm with a micropipette, the sperm suspension can be sonicated to break off the sperm tails. The resulting sperm heads can easily be injected into unfertilized eggs to induce the normal events of fertilization. With these injection procedures it is possible to test the fertilizing capacity of foreign sperm, of defective sperm, and even of “dead” sperm. We have found that the phenotype of the sperm does not reflect the genotype in terms of fertilizing ability after microinjection. Immotile and grossly defective sperm of the mouse when injected into the egg produce the same reactions that are produced by fertilization with healthy robust sperm. Thus we conclude that the complex set of interactions normally required for sperm to penetrate the egg investments and to fertilize the egg are biologically unnecessary and can be circumvented by direct injection of the sperm into the egg.
Interspecific hybrids and chimeras in mice
Authors: Rossant J. , Croy B. A. , Clark D. A. , Chapman V. M. 
Published: June 2005

AbstractInterspecific hybrids and chimeras in mammals provide unique tools for investigating problems in genetics and embryology, because of the degree of disparity between the two component genotypes. We have attempted to produce hybrids and chimeras between Mus musculus, the laboratory mouse, and Mus caroli, a wild species of mouse from Southeast Asia. M. musculus and M. caroli do not normally interbreed, although sterile hybrids can be produced at a low rate by artificial insemination. Extrinsic problems of genotypic incompatibility between the fetus and the maternal environment seem to be involved in poor hybrid survival, since M. caroli blastocysts also die when transferred to the M. musculus uterus. Death is associated with the generation of maternal T‐cells which are cytotoxic to M. caroli target cells in vitro. It is not yet clear whether this immune response is the primary cause of death or is secondary to breakdown of some other components of the fetal‐maternal interaction. It is clear, however, that it is the trophoblast layer that mediates survival or death of the foreign embryonic cells in the M. musculus juterus, since M. caroli inner cell mass cells can survive to term after injection into M. musculus blastocysts: Viable interspecific chimeras result. Even more convincing evidence is provided by the production of viable M. caroli offspring by trophoblast vesicle reconstitution using trophoblast of M. musculus genotype and inner‐cell mass of M. caroli type. Studies of properties of isolated trophoblast tissues have indicated that M. caroli trophoblast may differ from M. musculus in both its antigenic and immunosuppressive properties. Elucidation of trophoblast‐uterine interactions in these various interspecific pregnancies is being aided by the development of an in situ marker system, which can distinguish cells of the two species in sectioned material by in situ hybridization with a M. musculus satellite DNA probe. This same marker is also proving a very powerful tool for analyzing cell lineage development in chimeras.
Murine trisomy: Developmental profiles of the embryo, and isolation of trisomic cellular systems
Authors: Gropp A. , Winking H. , Herbst E. W. , Claussen C. P. 
Published: June 2005

AbstractMany questions related to the development and the phenotypic expression of trisomy (Ts) are amenable to systematic investigation in a mouse model that allows the induction of Ts 1 to 19 by a breeding design of mice heterozygous for Robertsonian metacentric chromosomes. Some Ts do not survive the first critical phase of organogenesis on days 11 to 12 of fetal development; others as Ts 12, 14, 16, 18, and 19, have a life span until or beyond birth. Model type studies of the morphogenesis of developmental anomalies (e.g. craniocerebral, cardiovascular, or placental) are possible in Ts with a longer developmental span, and Ts 16 of the mouse is considered as a natural model of human trisomy 21. The eventual breakdown and death of the trisomic organism are inevitable. There is considerable interest to find ways for rescue and longer survival of Ts in competitive developmental systems, as e.g., in Ts ⟷ 2n blastocyst chimeras, or by isolation of trisomic cellular or tissue systems. Thus, the transfer of Ts hemopoietic stem cells of the fetal liver to irradiated adult recipients is a means of studying the functional capacities and maturation of trisomic hemopoiesis and lymphopoiesis. Both are almost completely restored by Ts 12, 14, 18, and 19 stem cell transplantation with survival periods of more than 6 months. But in other Ts, as of chromosomes 13 or 16, such capacity of reconstitution is impaired. The stepwise analysis of the effects of chromosome triplication on the cell level, in isolated functional systems and in the embryonic organism, is a promising way to understand the phenotypic expression of genome anomalies in complex developmental processes.