bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vivo conduction properties of regenerating giant nerve fibers in earthworms
Authors: Balter R. J. , Drewes C. D. , McFall J. L. 
Published: June 2005

AbstractNon‐invasive electrophysiological techniques have been used to study spatial and temporal aspects of conduction properties in regenerating earthworm giant nerve fibers. The initial coupling of medial giant fiber (MGF) spikes across the lesion can occur as early as five (and usually within seven) days after severing the ventral nerve cord. In the case of the lateral giant fiber (LGF), the initial coupling of spikes across the lesion occurs as early as 12 days after severing the cord. During the first, few days after initial coupling across the lesion, properties of the recovering giant fibers included: a) intermittent and labile coupling of spikes across the lesion, b) long conduction times (up to 6 msec) across the lesion, c) frequent occurrence of, “rebound” spikes initiated in the lesion area, and d) similarity of conduction properties across the lesion for orthodromic and antidromic spikes. Three to four weeks after initial coupling, the following changes were observed: a) increased tendency for,1:1 coupling of spikes across the lesion, b) reduction in conduction time across the lesion, and c) decreased tendency for “rebound” spikes. The results are consistent with a model in which conduction across the lesion, during the first few days after initial coupling and thereafter, occurs by means of an electrical junction established between the severed giant fibers.
Further evidence for visual cell independent light effect on retina development in Tilapia leucosticta (teleostei)
Authors: Grün Gerd 
Published: June 2005

AbstractThe earlier conclusion that the influence of light on retina development in Tilapia leucosticta is not mediated by the visual cells has been tested by application of various light regimes. The effect of 10 days of continuous light resp. darkness on the growth of the inner plexiform layer is mimicked by only 24 hours of light resp. darkness when given on day 4. This is long before rods and cones become differentiated.
Effect of cAMP and related compounds on newt epidermal cell migration both in vivo and in vitro
Authors: Dunlap Mary K. , Donaldson Donald J. 
Published: June 2005

AbstractThe effect of cyclic AMP and related compounds on both in vivo and in vitro epidermal cell migration during wound closure in the adult newt was examined. Cyclic AMP (cAMP) mand N6, O2′‐didbutyryl cyclic AMP (bd‐cAMP) inhibited migration both in vivo and in vitro when used with equimolar concentrations of theophylline, an inhibitor of 3′, 5′‐cyclic nucleotide phosphodiesterase. Neither db‐cAMP nor theophylline alone inhibited migration in vivo. Adenosine 5′ monophosphate (AMP), cyclic guanosine 3′, 5′ monophosphate (cGMP) and imidazole, a potentiator of phosphodiesterase were tested in vivo and had no effect on migration. Isoproterenol and epinephrine, which are known to stimulate adenylate cyclase, inhibited migration in vitro. Experiments using the protein synthesis inhibitor, cycloheximide, suggest that cAMP could be acting partially through regulation of protein synthesis but that other factors are involved. Dibutyryl cyclic AMP and theophylline had no effect on the incorporation of 3H‐leucine into protein. The inhibition of migration both in vivo and in vitro provides further evidence for a role of a cAMP in the regulation of cell motility.
Amino acid metabolism and cell volume regulation in the little skate, Raja erinacea. II. Synthesis
Authors: King Patricia A. , Cha Chung‐Ja , Goldstein Leon 
Published: June 2005

AbstractThe capacity for synthesis of β‐alanine, sarcosine, and taurine was investigated in tissue slices from the little skate (Raja erinacea). Synthesis of β‐alanine was found to occur predominantly in the liver and at a rate comparable to the β‐alanine oxidation rate previously measured for this tissue. Synthesis rate did not change when tissues were incubated in a diluted saline medium or when skates were gradually acclimated to half‐strength seawater. Sarcosine was found to be synthesized primarily in the liver, but at a much lower rate than β‐alanine. Taurine synthesis could not be demonstrated definitely in any of the tissues tested. Amino acid analysis of liver, red blood cells, and wing muscle were performed on tissues of skates gradually acclimated to half‐strength seawater and then reacclimated to full‐strength seawater. Only β‐alanine levels returned to predilution values upon reacclimation to full‐strength seawater.
In vitro translatability of RNP‐particles from insect eggs and embryos (Smittia spec., Chironomidae, Diptera)
Authors: Jäckle Herbert 
Published: June 2005

AbstractMaternal messenger ribonucleoprotein (mRNP)‐particles from eggs and mRNP‐particles from embryos of the chironomid midge Smittia spec. were compared with respect to translatability in a mRNA‐dependent cell‐free translation system. The reticulocyte lysate system used was almost not stimulated by addition of native cytoplasmic mRNP‐particles from both eggs and embryos. RNP‐particles from embryos were fully translatable after partial release of proteins by high‐salt treatment. However, complete removal of proteins was necessary for translation of mRNP‐particles from eggs. Maternal mRNP‐particles of eggs consist of salt‐resistant RNP‐core proteins, which repressed translatability of the associated mRNA. The data support the hypothesis of “masked” maternal mRNA in insect embryos.
Effects of RNA inhibitors on the development of Drosophila embryos permeabilized by a new technique
Authors: Arking Robert , Parente Anthony 
Published: June 2005

AbstractThe molecular analysis of Drosophila embryogenesis has been hindered by the impermeable nature of the vitelline membrane, which has made it difficult to introduce exogenous substances into the developing embryo. We have developed a modification of the permeabilization technique of Limbourg and Zalokar ('73) in which octane is used to permeabilize the vitelline membrane and dimethylsulfoxide is used to facilitate the transport of exogenous substance across the cell membranes. The procedure is highly effective (ca. 95%) and is consistent with a high frequency of normal development. We have used this technique to analyze the effect in vivo of four inhibitors of RNA synthesis (alphaamanitin, actinomycin‐D, rifampin, and rifamycin SV) on the embryogenesis of Drosophila. We have found that there are characteristic stage‐specific alternations in the sensitivity of the embryo to these inhibitors which is reflected both by changes in the ID50 dosages and by changes in the developmental abnormalities caused by the drugs. Embryos aged 2–12 hours old undergo a developmental arrest within 30 minutes after application of the inhibitors. Embryos older than 12 hours are able to develop for 140+ minutes after treatment before arresting. The effects of these drugs are consistent with the idea that there exists a definite sequential program of gene activity that is necessary to the normal embryonic development of Drosophila.
Innervation of the crayfish thoracic deep flexor musculature
Authors: Crabtree Robert L. , Sherman R. G. 
Published: June 2005

AbstractThe innervation and neuromuscular physiology of the deep flexor muscles in the thorax of the crayfish, Orconectes rusticus are described. Four muscles arise ventrally from the endophragmal shelf and join at segmental inscriptions to form a single functional mass. Deep flexor 1 (DF1) extends from the anterior thoracic endoskeleton to be joined by DF2, DF3, and DF4 in more posterior segments. The mass inserts on the abdominal flexor at the common flexor inscription.Motor axons from thoracic ganglionic third roots 1–3 innervate the deep flexor muscles. Light and electron microscopical examination indicates that the third root of the first thoracic ganglion contains only three or four axons that innervate the musculature, and the third root of the second thoracic ganglion usually contains five. The largest number of deep flexor axons (10) occurs in the third root of the third thoracic ganglion.Methylene blue staining and microelectrode recording methods show that each deep flexor muscle fiber is innervated by three motoneurons: the motor giant, a non‐giant excitor and an inhibitor. The motor giant elicits excitatory postsynaptic potentials (EPSPs) that rapidly antifacilitate, while the non‐giant excitor elicits EPSPs that do not antifacilitate. Both excitors produce spiking activity in the deep flexors. The inhibitory motor neuron reduces the amplitude and duration of the EPSP and prevents spiking activity. These results show that the thoracic deep flexor system is similar to the homologous system in the abdomen.
Entire litters developed from transferred eggs in whole body X‐irradiated female mice
Authors: Lin T. P. 
Published: June 2005

AbstractThe sensitivity of mouse eggs to sublethal X‐irradiation was determined in vitro and in vivo with regard to the development of donor litters in foster mothers. One thousand seven hundred fifty‐eight unfertilized eggs of agouti dark‐eyed donor mice were transferred into 293 unirradiated or X‐irradiated, mated female pink‐eyed mice. Two hundred thirty‐nine recipients became pregnant; of these 35 produced litters containing solely dark‐eyed fetuses. Sublethal doses of X‐radiation administered to donor eggs in vitro before transferring into unirradiated recipients did not influence significantly the number of litters of exclusively dark‐eyed fetuses produced. However, recipients irradiated by 250 roentgens (r) produced more solely dark‐eyed litters than did those irradiated with 100 r. In 21 pregnant females irradiated by 100 r, only 3 (14%) developed solely dark‐eyed fetuses as compared to 22 pregnant females irradiated by 250 r, of which 13 (59%) developed solely dark‐eyed fetuses, all from unirradiated, transferred eggs. Of another group of 22 pregnant females which received 250 r body irradiation and subsequently received eggs also irradiated by 250 r, only 7 (32%) produced litters of dark‐eyed fetuses. No one female of these three groups carried native fetuses. Such radiation‐induced infertility resulting from damage of native eggs rather than loss of the mother's ability to carry a pregnancy, is frequently remedied by egg transfer.
Morphogenetic movements in acipenserid embryos
Authors: Ballard William W. , Ginsburg Anna S. 
Published: June 2005

AbstractA fate map for the late blastula stage of a sturgeon is presented for the first time, together with descriptions of the principal morphogenetic movements, and a timetable of involution, based on vital dye experiments on Huso and three species of Acipenser. Massive migration of internal cells from the blastocoel roof to an inner marginal zone precedes the earliest drift of cells at the surface. The definitive endoderm which lines the archenteron is derived from a complete band of cells encircling 360° of the surface of the blastula from the equator up to 20° latitude. Their movement across the lips of the blastopore to the interior is strictly defined as an involution, not an invagination. After involution of the prechordal endoderm, the right and left components of the sub‐notochordal endoderm fuse with each other as they pass across the blastopore lip in the midline. Above the band of prospective endoderm on the blastula surface there is a complete band of both surface and inner marginal cells up from 20° to about 30° latitude, which produces notochord and somite mesoderm, also by involution. Mesoderm of the tail has all reached the interior before closure of the blastopore. Head mesoderm, and intermediate and lateral plate mesoderm are not represented at or near the blastula surface. The neural plate is derived from material at and immediately inside the blastula surface lying above 30° latitude and between right and left 90° longitudes.The remarkable contrast between the morphogenetic movements and fate maps of the meroblastic teleost and the holoblastic sturgeon embryos—both actinopterygian fishes—and the close resemblance of sturgeon embryos to those of frogs, are discussed.
Developmental and ploidy characteristics of “senescent” unfertilized eggs of Xenopus laevis
Authors: Blackler Antonie W. , Cassidy Donna M. 
Published: June 2005

AbstractUnfertilized eggs of Xenopus laevis have been stored in a high salt physiological saline (De Boer's solution) over a period of about 24 hours. During this time, aliquots have been subjected to lowered salinity and fertilized. The stored eggs undergo a defined series of morphological changes, which are initially reversible upon fertilization. Length of storage may have little or no effect on the capacity of the eggs to undergo cleavage, but the normal developmental capacity declines with increasing storage time. Among the characteristics of this decline is a regressive cytokinesis, early arrest, and the appearance in surviving larvae of a definable syndrome of morphological type. Increasing storage times predispose the eggs to subsequent triploid development, the triploidy arising as a consequence of failure of second polar body emission. The possible interest of these findings for a model system of mammalian gamete aging is discussed.
Appearance of RNA with a specific size class of poly(A) in oocytes and eggs in HCG‐stimulated Xenopus laevis females
Authors: Sagata N. , Shiokawa K. , Yamana K. 
Published: June 2005

AbstractUsing a 3H‐poly(U) binding technique, poly(A) content has been measured in Xenopus laevis eggs consisting of two groups: one was obtained from females 12 to 16 hr after a single injection of human chorionic gonadotropin (HCG) (designated “unstimulated” eggs), and the other was obtained one week later from the same females by the second injection of the hormone (“stimulated” eggs). The stimulated egg contained about a 1.2‐fold larger amount of poly(A) than the unstimulated one. Gel electrophoresis has revealed that this slight but reproducible increase in the poly(A) (i.e., about 80 nucleotides long). This poly(A) was also detectable in the oocytes obtained one week after a single injection but not in those from uninjected females. Poly(A)+ RNA was analyzed by sucrose density gradient centrifugation, and it has been shown that most of the 80 nucleotidelong poly(A) sequences in the stimulated eggs were associated with RNA whose size distribution was less heterogeneous than, and hence distinguishable from, that of the bulk poly(A)+ RNA. The possibility is discussed that HCG hormone may stimulate the synthesis of a specific class of poly(A)+ RNA in smaller oocytes, which may not normally take place to a significant extent during maturation.
Isolation of pituitary proteins from Mexican axolotls (Ambystoma mexicanum COPE) by polyacrylamide gel electrophoresis. I. Assay for thyrotropic activity
Authors: Schultheiss Hartmut 
Published: June 2005

AbstractPituitaries from male, sexually mature neotenic axolotls were subjected to polyacrylamide gel electrophoresis (PAGE). Eight protein fractions were isolated from unstained gels. They were tested for thyrotropic activity in two different systems: 1) 131iodide uptake into the thyroids of hypophysectomized neotenic axolotls was followed over a 72‐hour period after pretreatment with the protein fractions (one pituitary‐equivalent per animal and day); 2) The thyroxine (T4)‐release in vitro from thyroid glands was measured by radioimmunoassay (RIA). PAGE fractions were added to the culture medium. Three fractions (A1, A2, and A4) were found to increase 131iodide uptake significantly. Specific release of T4 by axolotl thyroid glands was stimulated by only one fraction (B2), corresponding to the two fractions (A1 and A2) which caused the greatest 131I uptake. The T4‐release was dose‐dependent, and on a μg‐basis, axolotl‐TSH, (a‐TSH), B2, was approximately eight times more potent than the reference bovine TSH (b‐TSH), NIH‐TSH‐B8. It was shown the pituitary of neotenic axolotls contains proteins with high thyrotropic activity.
Age‐ and region‐dependent redistribution of con A binding sites on chick wing‐bud mesoderm cells
Authors: Paulsen Douglas F. , Finch Robert A. , Parker Curtis L. 
Published: June 2005

AbstractThe distribution of concanavalin A (con A) binding sites on chick wing‐bud mesoderm cells from two different developmental stages and from different regions of the same embyronic limbs was examined. Fluorescein isothiocyanate (FITC)‐labeled con A binding sites on mesoderm cells from whole stage 19–20 and the distal third of stage 25 limbs redistributed from a random array over the cell surface to form clusters or caps of binding sites. In contrast, a significantly smaller percentage of developmentally “older” mesoderm cells from the proximal third of stage 25 limbs underwent redistribution of bound con A from its normal random arrangement. In order to further examine the basis for the decrease in con A redistribution in the stage 25 proximal cells, this segment was subdivided into a core (presumptive chondrogenic) and peripheral (presumptive myogenic) region. The results of con A redistribution studies utilizing these two cell populations indicate that a significantly smaller percentage of the core cells are capable of forming clusters or caps. Likewise, in agglutination studies, core cells proved significantly less susceptible to con A‐induced agglutination. These findings indicates that the differences in agglutination and con A redistribution, seen when comparing the proximal cells with the other cell populations, is attributable to a subpopulation of the proximal cells, specifically, those located in the chondrogenic core region. Since the proximal core and peripheral cells are of the same developmental age, these findings suggest that developmental age is not solely responsible for the differences reported here. Thus, prospective phenotype appears also to be involved in the decreased agglutination and a con A redistribution of the chondrogenic core cells.
Lanthanum blockade of serotonin release from the branchial nerve of the mussel Mytilus edulis
Authors: Stefano G. B. , Brogan J. J. , Aiello E. , Hiripi L. 
Published: June 2005

AbstractThe study demonstrates that lanthanum at low levels (5mM) can block the neuronal release of serotonin. In addition, the postlateral ciliated cell serotonergic receptor is not affected by this blockade at this particular concentration of lanthanum, but is affected at higher levels (10 mM).
An experimental analysis of shoulder and lateral body wall development in the chick embryo
Authors: Yander Gail , Searls Robert L. 
Published: June 2005

AbstractDevelopment of the shoulder and a change in the axis of outgrowth of the wing in the chick embryo have been shown to be accompanied by morphogenetic movements in the lateral body wall adjacent to the base of the wing. The manner in which the cells moved was studied by grafting labeled mesoderm into unlabeled hosts and by periodic photographs of carbon particles placed in live embryos. Histological techniques were used to determine the final location of the markers, and maps were constructed of the cell movements. It was observed that cells in the lateral body wall cranial to the wing and overlying the pleural coelom moved caudally to form the base of the shoulder. This movement occurred between stage 23 and stage 27. Starting at stage 25, the cells in the lateral body wall caudal to the wing moved ventrally and then cranially to form the sternum and connective tissue of the ventro‐medial thoracic body wall; this movement was complete by stage 31. As a result of these two morphogenetic movements, cells in the proximal portion of the wing were also displaced. The net effect is formation of the shoulder, while the base of the wing rotates ventrally with respect to the somites.
Relation of mitochondria‐rich chloride cells to active chloride transport in the skin of a marine teleost
Authors: Marshall William S. , Nishioka Richard S. 
Published: June 2005

AbstractMitochondria‐rich cells in the skin of the marine teleost, Gillichthys mirabilis, were found to be ultrastructurally similar to typical chloride‐secreting cells of marine fish gill, but had a tall, spindlelike shape due to the thickness of the stratified epithelium. The fluorophore, dimethylaminostyrylethylpyridiniumiodide (DASPEI), was used to visualize and count skin chloride cells so that cell density could be regressed against the in vitro short‐circuit current (ISC) measured on the same tissue. The regression (r2 = 0.76; n = 72) demonstrated that chloride cells are responsible for anion transport across Grillichthys skin.
Ecdysteroid titers of juvenile lobsters following molt induction
Authors: Chang Ernest S. , Bruce Marilyn J. 
Published: June 2005

AbstractBy means of radioimmunoassay, the circulating ecdysteroid (molting hormone) titers have been obtained for both normal and eyestalkablated juvenile lobsters. It is seen that these animals, following molt induction, have rapid elevations in their hemolymph ecdysteroids. The hormonal titers for these premolt‐induced animals closely resemble those of normal animals. In addition, the effects of temperature upon molting and ecdysteroid titers are examined in ablated lobsters.
Interlimb coordination in 20‐day‐old rat fetuses
Authors: Bekoff Anne , Lau Bradley 
Published: June 2005

AbstractEvidence for short sequences of interlimb coordination was found in 20‐day‐old rat fetuses. Frame‐by‐frame analysis of videotape records showed phase relationships indicating a pattern of alternation in sequences involving forelimb‐forelimb and hindlimb‐hindlimb coordination. Forelimb‐hind‐limb coordination was not observed.
Abdominal extension‐evoking interneurons in crayfish: Characteristics of the ganglionic driving networks
Authors: Williams Benjamin J. , Larimer James L. 
Published: June 2005

AbstractSeveral different paradigms of extension‐evoking command fiber (CF) stimulation were used in order to characterize functional properties of the networks controlling abdominal posture in the crayfish. The types of connections between CFs and abdominal postural driving networks were first studied by stimulating several extension CFs from the same preparation at different frequencies. Differences in the recruitment order of extensor motoneurons imply that each CF makes unique synaptic connections with the abdominal ganglionic driving interneurons and/or the postural efferents. Furthermore, the ability of an extension CF to activate excitatory efferents after another extension CF has been driven to fatigue suggests that each CF has functionally distinct pathways to the extensor motoneuron pool. The second main objective of this paper was to determine if direct extension CF stimulation would produce integrative properties of the driving networks similar to those seen previously in the reflexively extending animal. As in reflex‐evoked behavior, the ganglionic driving networks are capable of spatially summating the input from two co‐activated CFs. In particular, low frequency co‐activation of two CFs recruited motoneurons which were inactive when single CFs were stimulated alone at the same frequency. Co‐stimulation of an extension CF with strong flexor‐biasing sensory input suppressed the flexors and resulted in a nearly pure extension motor program similar to that seen during reflex‐evoked extensions. Thus, overriding of antagonistic reflexes by CF activity argues for synaptic systems in each ganglion which rejects or reduces the gain of opposing relflexes, including those due to reafference during the commanded movements. These results strongly suggest a causal role for CFs in the generation of reflexive behavior in the freely behaving animal.
Norepinephrine: Its presence in the central nervous system of the bivalve mollusc, Mytilus edulis
Authors: Stefano George B. , Catapane Edward J. 
Published: June 2005

AbstractThe present study demonstrates the existence of norepinephrine in the ganglia of the mussel Mytilus edulis. The identification of this catecholamine is based on the specificity of the radioenzymatic and spectroflurometric methods of analysis and by the specific actions of FLA‐63. Key words: norepinephrine, radioenzymatic, FLA‐63‐DOPS, invertebrate nervous tissue.