bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cell cycle remodeling requires cell–cell interactions in developing Xenopus embryos
Authors: Frederick Debra L. , Andrews Matthew T. 
Published: June 2005

AbstractFlow cytometric analysis has revealed a general remodeling of the cell cycle in developing Xenopus embryos. During early gastrulation the cell cycle is dominated by S phase, with 82% of all interphase nuclei in the S phase fraction. As development proceeds over the next 60 hours, a gradual decline in S phase cells is proportional to an increase in the number of cells in G1. By the late tailbud stage, 85% of all nuclei are found in the G1 fraction, approximating the cell cycle profile of adult somatic cells. Cell cycle remodeling occurs on schedule even in embryos that have been dissociated into a loose mound of cells which remain in close proximity to one another. However, cells that have been widely separated by manual dispersion do not undergo remodeling. These dispersed cells maintain an S phase‐dominated cell cycle and continue to show patterns of blastula and gastrula gene expression at least 30 hours beyond gastrulation. We conclude that cell cycle remodeling occurs in the absence of an intact embryo but requires the inductive influences associated with a community of cells. © Wiley‐Liss, Inc.
Cyclical morphodynamics of hair bundles in sea anemones: Second messenger pathways
Authors: Mire‐Thibodeaux Patricia , Watson Glen M. 
Published: June 2005

AbstractDespite lacking sensory organs, sea anemones apparently integrate chemical and mechanical sensory input from prey in the regulation of nematocyst discharge. Exposing anemones to exogenous N‐acetylated sugars induces hair bundles to elongate while shifting nematocyst discharge to lower frequencies matching swimming movements of prey. A pharmacological approach was employed to examine the transduction events involved in the sugar induced “tuning” of anemone hair bundles. Photoactivation of caged cyclic‐AMP (cAMP) induces bundles to elongate to a maximum length by 4 min and subsequently to shorten to near control lengths by 8 min. Continuous stimulation with sugar produces a similar effect with the cycle continuing through at least 20 min. With sugar stimulation, nematocyst discharge into targets vibrating at 5 Hz also follows the same, cyclical pattern. Bundles do not elongate in the combined presence of N‐acetylated sugars and H89, an inhibitor of protein kinase A. Elongated bundles either do not shorten, or rapidly recover from shortening, if caged cAMP is photoactivated 3.5 min after the initiation of sugar stimulation. Furthermore, bundle shortening is blocked by caffeine, an inhibitor of phosphodiesterase, W7, an inhibitor of calmodulin, nifedipine, an inhibitor of certain calcium channels, or cypermethrin, an inhibitor of protein phosphatase 2B (PP2B). Thus, chemodetection of sugars may involve an immediate elevation of intracellular cAMP, leading to an activation of protein kinase A, inducing bundles to elongate. Subsequently, calcium channels may be activated leading to a calcium/calmodulin dependent enhancement of phosphodiesterase and an activation of PP2B, inducing bundles to shorten by degrading cAMP and dephosphorylating proteins. © Wiley‐Liss, Inc.
Ultrastructural changes in micropylar and granulosa cells during in vitro oocyte maturation in the medaka, Oryzias latipes
Authors: Nakashima S. , Iwamatsu T. 
Published: June 2005

AbstractUltrastructural changes in micropylar cells during in vitro oogenesis in the medaka, Oryzias latipes, were examined by electron microscopy. In micropylar cells, bundles of microtubules and tonofilaments are well developed by the post‐vitellogenic stage of oogenesis. At the initiation of germinal vesicle breakdown (GVBD), the twisted cytoplasmic protrusion of the enlarged micropylar cell extends to the oocyte surface through the micropylar canal of the chorion. Various kinds of organelles in the cytoplasm of the micropylar cell show a characteristic pattern of distribution. Extensive tonofilaments occupy a large portion of the cytoplasm in the main cell body, while spiraling bundles of both microtubules and tonofilaments are observed along with mitochondria in the cytoplasmic protrusion. About 3 hours after GVBD, the cytoplasmic protrusion begins to shrink and gradually withdraw from the micropylar canal. It has few or no bundles of microtubules and tonofilaments during its withdrawal. The micropylar cell finally becomes oval in shape by 6 hours after the initiation of GVBD as its cytoplasmic protrusion shrinks completely. These observations suggest that these cell organelles are involved in forming, supporting, and/or withdrawing the cytoplasmic protrusion of the micropylar cell. © Wiley‐Liss, Inc.
Distribution of myoplasmic cytoskeletal domains among egg fragments of the ascidian Ciona savignyi: The concentration of deep filamentous lattice in the fragment enriched with muscle determinants
Authors: Marikawa Yusuke 
Published: June 2005

AbstractThe myoplasm of the ascidian egg contains muscle determinants and is composed of myoplasmic cytoskeletal domain (MCD). MCD consists of two interacting parts, a plasma membrane lamina (PML) and a deep filamentous lattice (DFL). We showed that, among the four types of egg fragments that are produced by centrifugation of unfertilized Ciona savignyi eggs, muscle determinants are concentrated in only one type (black fragment) and are virtually absent in the others (clear, brown and red fragments). In this study, to investigate the relationship between MCD and muscle determinants, we compared the distribution of PML and DFL among the egg fragments. Actin filament, which is a component of PML, was found in all fragments. In contrast, p58, which is a protein recognized by an anti‐intermediate filament antibody and is a component of DFL, was highly concentrated in black fragments and excluded from the other three. In addition, pigment granules and mitochondria, both of which are embedded in DFL, were also concentrated in black fragments. Thus, the distribution of muscle deteminants among the egg fragments coincided with that of DFL, supporting the possibility that muscle determinants may be associated with DFL rather than with PML. © 1995 Wiley‐Liss, Inc.
In vitro study of vitellogenesis in the blue crab (Callinectes sapidus): Site and control of vitellin synthesis
Authors: Lee Chi‐Ying , Watson R. Douglas 
Published: June 2005

AbstractThe determine the site of vitellin (Vn) synthesis in the blue crab, Callinectes sapidus, tissues (ovary, hepatopancreas, and gill) from adult female crabs were incubated in vitro with [35S]methionine. Tissue extracts were separated by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and radiolabeled proteins were visualized by autoradiography: Four radiolabeled ovarian proteins (188, 168, 109, and 86 kDa) comigrated with the subunits of Vn. A Western blot analysis confirmed that these ovarian proteins were the Vn subunits. Proteins in the hepatopancreas and gill were also radiolabeled but were not Vn‐immunoreactive. In vitro incorporation of [35S] methionine into ovarian proteins was inhibited by an extract of eyestalks; the inhibition was dose‐dependent and specific. Autoradiography of the electrophoretically separated ovarian proteins revealed that the eyestalk extract inhibited incorporation of [35S] methionine into numerous proteins, including the Vn subunits. These results suggest that the ovary is a site of Vn synthesis and that the eyestalks contain a factor or factors that directly inhibit the synthesis of Vn and other ovarian proteins. It is anticipated that the suppression of ovarian protein synthesis will be a useful bioassay for blue crab vitellogenesis‐inhibiting hormone. © 1995 Wiley‐Liss, Inc.
Proteins of crustacean exoskeleton: III. Glycoproteins in the Bermuda land crab Gecarcinus lateralis
Authors: Kumari S. Sindhu , Skinner Dorothy M. 
Published: June 2005

AbstractChitin and protein are major components of crustacean exoskeletons. In insect cuticles, glycosylation is one of the predominant post‐translational modifications of the proteins. Investigations of glycosylation of crustacean exoskeletal proteins are much more limited. We have used lectins to follow changes in glycosylation of proteins in the exoskeletal layers of the Bermuda land crab Gecarcinus lateralis at selected stages of the intermolt cycle. Proteins extracted from the individual layers during anecdysis and late proecdysis as well as from the layers of exuviae were electrophoresed on sodium dodecyl sulfate (SDS)‐polyacrylamidegels, blotted to polyvinylidene difluoride membranes, and reacted with biotinylated lectins. Seven lectins were tested: concanavalin A (Con A), soybean agglutinin (SBA), wheat germ agglutinin (WGA), Dolichos biflorus agglutinin (DBA), Ulex europaeus agglutinin(UEA I), Ricinus communis agglutinin (RCA120), and peanut agglutinin (PNA). Con A, which binds primarily to mannose residues, produced the strongest signals. Duringanecdysis, most of the binding occurred with protein bands larger than 31 kDa, while in lateproecdysis and in layers from exuviae, small as well as large proteins were bound. N‐glycosidase F digestion of electrotransferred proteins and subsequent treatment with Con A indicated both N‐linked and O‐linked glycosylation. SBA, which binds to both α‐and β‐linked N‐acetylgalactosamine, was the second most reactive lectin, and the number of exoskeletal proteins to which it bound also increased in late proecdysis. Little or no binding of DBA, RCA120, or PNA, which react with α‐linked N‐acetylgalactosamine, indicated that the N‐acetylgalactosamine was β‐linked. The specificity of binding of Con A or SBA was demonstrated by inhibition with methyl‐α‐D‐mannopyranoside and N‐acetyl‐D‐galactosamine, respectively. Binding of UEAI revealed the presence of fucose residues on a few proteins. As the exoskeleton was degraded during proecdysis, protein bands that were not detected by lectin binding during anecdysis were modified in such a way that they became accessible to lectins. © 1995 Wiley‐Liss, Inc.
Proteolytic cleavage of vitellogenin and yolk proteins during vitellogenin uptake and oocyte maturation in barfin flounder (Verasper moseri)
Authors: Matsubara Takahiro , Sawano Keiichi 
Published: June 2005

AbstractVitellogenin (Vg) and vitellogenin‐derived yolk proteins of growing oocytes and ovulated eggs were purified and characterized to evaluate structural changes of yolk proteins during oocyte growth and maturation in barfin flounder, Verasper moseri, a marine teleost which lays pelagic eggs. Native circulating vitellogenin, estimated to be a 520 kDa protein using Superose 6 column chromatography, cleaved into the 410 kDa major yolk protein, lipovitellin (Lv), in vitellogenic oocytes. An additional minor yolk protein at 19 kDa in native form, which was immunoreactive to an antiserum raised against Vg, and a highly phosphorylated 38 kDa band of phosvitin (Pv) in SDS‐PAGE with reduction were also identified in vitellogenic oocytes. Analysis of the amino acid composition of the 19 kDa yolk protein showed it to be similar to the β′‐component of egg yolk from salmonid fish. The 410 kDa Lv in vitellogenic oocytes was proteolytically cleaved into an 170 kDa major yolk protein during final oocyte maturation. The close similarity of amino acid composition between the two proteins combined with the results of lipid analysis suggested that the 410 kDa Lv cleaved into two homologous 170 kDa monomeric Lv. Both 19 kDa yolk protein (β′‐component) and Pv became undetectable after oocyte maturation. We propose that the three classes of yolk proteins (Lv, Pv, and β′‐component) are products of Vg cleavage, and that all of them undergo proteolysis again during oocyte maturation. © 1995 Wiley‐Liss, Inc.
External and internal influences on indices of physiological stress: II. Seasonal and size‐related variations in blood composition in free‐living lizards, Sceloporus occidentalis
Authors: Dunlap Kent D. 
Published: June 2005

AbstractSeasonal changes in blood composition (plasma osmolality, total plasma protein, hematocrit) in two free‐living populations of fence lizards, Sceloporus occidentalis, one living in a very arid environment (Pearblossom, CA) and another in a milder desert (Bend, OR), were analyzed. In this analysis, two features of reptilian physiology and ecology were incorporated: ontogenetic variation in blood composition and seasonal variation in body‐size distribution. The population living in the arid environment, but not the mild environment, exhibited significant seasonal changes in blood composition: mean plasma osmolality increased (345 ± 4 to 356 ± 3 mOsmol/kg) and mean plasma protein (4.19 ± 0.20 to 3.34 ± 0.14 g/dl) and hematocrit decreased (43.8 ± 0.3 to 31.6 ± 0.4) from April to August. These changes suggested that the physiological condition of the California population was affected by seasonal changes in the external environment. However, among individuals, a significant portion of the variation in blood composition was associated with an internal factor, body size. Larger lizards had higher osmolality, total protein, and hematocrit than smaller lizards in all seasons. In addition, the mean body size of active lizards decreased from April to August in California, but not Oregon. Because the body‐size distribution of active lizards in California shifted between seasons, changes in mean population values of these blood parameters probably do not accurately reflect changes that occur within individuals and therefore may be misleading in assessing the physiological consequences of drought. © 1995 Wiley‐Liss, Inc.
Serotonin‐induced parturition in the fingernail clam Sphaerium (Musculium) transversum (Say)
Authors: Fong Peter P. , Warner Marlene 
Published: June 2005

AbstractParturition in the freshwater fingernail clam Sphaerium (=Musculium) transversum (Say) was induced by external application of both 10−4 and 10−3 M serotonin [5‐hy‐droxytryptamine (5‐HT)]. 5‐HT induced release of viable juveniles within 30–60 min of application. Parturitions in 5‐HT (10−3 M) occurred sooner and more often than in 5‐HT (10−5 or 10−4 M) or in artificial pond water. The numbers of juveniles per parturition in 5‐HT varied from one to nine. The parturition response to 5‐HT was completely blocked by 10−4 M methiothepin (a vertebrate 5‐HT1/5‐HT2 receptor antagonist) known to bind with high affinity to gastropod 5‐HT receptors and to block 5‐HT‐induced spawning in other freshwater bivalves. However, parturition was not induced by 8‐OH‐DPAT (8‐hydroxy‐dipropylaminotetralin HBr, a vertebrate 5‐HT1A receptor agonist), a potent inducer of spawning in freshwater bivalves. Thus, the pharmacological profile of the 5‐HT receptor(s) mediating parturition in S. transversum may be unlike that mediating spawning in other bivalves. This is the first report of 5‐HT‐induced parturition in any brooding bivalve. © 1995 Wiley‐Liss, Inc.
Integration of photoperiodic and food cues to time changes in reproductive physiology by an opportunistic breeder, the red crossbill, Loxia curvirostra (Aves: Carduelinae)
Authors: Hahn Thomas P. 
Published: June 2005

AbstractOpportunistic breeders presumably use short‐term cues (e.g., food) instead of photoperiod to time breeding. This view cannot explain regulation of reproductive patterns in one opportunist, the red crossbill (Loxia curvirostra). Captive crossbills held on natural photoperiod, constant temperature, and ad libitum food express cycles of gonadal development, secretion of luteinizing hormone (LH), fat deposition, body mass, hematocrit, and molt. This shows that changing food availability (presumed to drive reproduction in these birds) is not necessary for expression of a seasonal cycle. However, changes in food availability can modulate this seasonal pattern. Reduced food intake attenuates long day induced LH secretion. Furthermore, long day stimulated birds show greater testicular development if shifted from restricted to ad libitum food than if provided ad libitum food continuously. Ad libitum food alone does not stimulate complete reproductive development in winter, when crossbills often breed opportunistically in the wild. Additional stimulation by other factors (e.g., social interactions) is critical at this time. Thus, crossbills regulate their basic annual cycle with photoperiod and superimpose opportunistic responses to supplementary cues (e.g., food and social factors) on this underlying seasonality. This permits crossbills to adjust to both seasonally predictable and unpredictable changes in their environment. © 1995 Wiley‐Liss, Inc.
Mixed finite element analysis of a thermally nonlinear coupled problem
Authors: Zhu Jiang , Loula Abimael F. D. 
Published: June 2005

AbstractIn Loula and Zhou [Comput Appl Math 20 (2001), 321–339], a thermally coupled nonlinear elliptic system modeling a large class of engineering problems was considered, and some mathematical and numerical analyses (C0 Lagrangian finite elements combined with a fixed point algorithm) were given. To continue our work, we propose in this article a mixed method for the potential equation and present the corresponding analyses and numerical implementations. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2006
A supervised learning method using duality in the artificial neuron model
Authors: Yamada Keiichi , Kuroyanagi Susumu , Iwata Akira 
Published: June 2005

AbstractIn a layered neural network, the error backpropagation method is generally used as the supervised learning procedure for the hidden layer, which cannot be observed from the outside. In order to apply the method, however, the output function of the neuron model must be differentiable. This paper proposes a supervised learning method for the hidden layer neurons in which the teaching signal is calculated for the hidden layer neurons, by utilizing the learning rule for the connection weight and the duality in the output layer neuron. The method is applicable so long as the neuron model contains duality, and it does not require that the output layer neurons or the hidden layer neurons be differentiable. As an example of a case in which the error backpropagation cannot be applied, a perceptron composed of neurons with a step output function is considered. The proposed method is applied, and the learning rule for the whole network is constructed. The XOR problem was actually learned by the network, and the same learning success rate was obtained as in the error backpropagation method for a perceptron composed of neurons with a sigmoid output function. © 2005 Wiley Periodicals, Inc. Syst Comp Jpn, 36(9): 34–42, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20206
Pulsed neural networks based on delta‐sigma modulation with GHA learning rule and their hardware implementation
Authors: Murahashi Yoshimitsu , Hotta Hirohisa , Doki Shinji , Okuma Shigeru 
Published: June 2005

AbstractIn order to achieve fast parallel processing operation by a neural network, it is desirable to implement all neurons in parallel in hardware rather than to realize operation by serial operation in software. The authors have proposed a pulsed neural network based on ΔΣ modulation which is suited to the hardware implementation of digital circuits. The proposed neural network can be realized on a small circuit scale, since the variable can be represented by a ΔΣ‐modulated 1‐bit pulse signal. Highly accurate operation can be realized even though only 1 bit is used. This paper proposes a hardware implementation of the above neural network. A neural network with built‐in GHA learning rule is hardware implemented on an FPGA, and its operation is investigated. The proposed neural network and CPU are implemented on an FPGA and are compared in terms of the number of bits that can be processed in unit time per unit of circuit scale. The proposed scheme achieved an evaluation score 200 times as great as a software realization on a CPU. © 2005 Wiley Periodicals, Inc. Syst Comp Jpn, 36(9): 14–24, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20235
The incidence of malformations in Birmingham, England, 1950–1959
Authors: Leck Ian , Record R. G. , McKeown Thomas , Edwards J. H. 
Published: June 2005

AbstractAn attempt was made to identify all malformations among the 190,236 births that occurred in Birmingham in the ten years 1950–59. This was done by examining (a) obstetric summaries completed either by hospital staff or, for domiciliary births, by midwives; and (b) notifications of stillbirths, certificates of cause of death, and necropsy reports of infants who died in the first two weeks. The number of malformed individuals found was 3637 (19.1 per 1000 births).A more complete ascertainment was achieved in respect of the 1950–54 births by following the children to the age of six years and searching hospital records, death registers, necropsy reports, and the City's Public Health and Education Departments' registers of the physically handicapped and of the mentally subnormal. By these methods 2527 malformed individuals in a population of 94,474 births were identified (26.7 per 1000). The malformation rate was higher for hospital births than for children born at home; the difference was due to selection of patients for hospital delivery and not to inferior recording of domiciliary births.Details of all malformations recorded are given in table 6 and in the appendix. The most frequent malformations, each with an incidence of at least one per 1000 births, were clubfoot, cardiac anomalies, anencephalus, spina bifida, clefts of lip and palate, Down's disease, hydrocephalus, and polydactyly. These accounted for three–fifths of the total. Combinations of several malformations in the same individual occurred much more frequently than if association between malformations were fortuitous. Apart from the well–known associations of cardiac malformations with Down's disease and clubfoot with spina bifida and anencephalus, the most frequent combinations noted were cardiac defects with clubfoot and with clefts of lip and palate, and clubfoot with hydronephrosis and with reduction deformities of the upper limb.
Studies of vitamin A‐induced teratogenesis: Effects on embryonic mesenchyme and epithelium, and on incorporation of H3‐thymidine
Authors: Kochhar D. M. 
Published: June 2005

AbstractSome aspects of tissue differentiation were studied in 13‐day rat embryos after vitamin A treatment of their mothers on days 10, 11, and 12 of gestation. Severely affected embryos showed extensive growth retardation. Inhibition of cell proliferation, assumed from a decreased rate of H3‐thymidine uptake, was found in the liver, loose mesenchyme of the cephalic region, posterior region of the palatine shelves, trigeminal nucleus, and in some areas of the skin. Other tissues investigated showed no inhibition.Development of the face in these embryos was characterized by the appearance of defects in the mesoderm of the maxillary process and in the oral epithelium. It is suggested that palatal and dental abnormalities of vitamin A‐treated embryos arise because of some initial changes in the epithelium, which subsequently lead to a disrupted epithelial‐mesodermal relation in this region, so essential for normal development.Some physicochemical properties of vitamin A, such as its high surface activity and its effect on membrane permeability, enable it to have widespread effects. Information about the importance of these phenomena in the developing embryo must await further elucidation of the mechanism of action of vitamin A in biological organisms in general.