bluuebunny/crossref_metadata_2025 huggingface dataset:
Aminoethylphosphonic acid‐containing glycoproteins: The acid mucopolysaccharide‐like components in mucus from Metridium senile (L.)
Authors: Bunde Terry A. , Dearlove George E. , Bishop Stephen H.
Published: June 2005

The sea anemone, Metridium senile, is covered with a sticky mucus which facilitates the trapping of plankton from the sea water. Histochemical procedures indicate that this acid mucopolysaccharide‐like (AMPS‐like) mucus is secreted by the columnar epithelial cells of the body surface. High Pressure Liquid Chromatography resolves the mucus into two high molecular weight acidic glycoproteins, neither of which contains any of the typical AMPS substituents of higher organisms (sulfate esters, glucuronic acid and sialic acid). Both of these glycoprotein fractions do, however, contain 2‐aminoethylphosphonic acid (AEP). Histochemical procedures carried out in conjunction with wet chemical analyses indicate that these AEP‐glycoprotein complexes not only account for the AMPS‐like staining material on the surface (mucus) of these animals, but also may have some function in the intracellular matrix.
Cyclic AMP and ouabain‐binding sites in the rectal gland of the dogfish Scyliorhinus canicula
Authors: Shuttleworth T. J. , Thompson J. L.
Published: June 2005

A technique for measuring the binding of 3H ouabain to tissue from the elasmobranch rectal gland is described. Concentrations of dibutyryl cAMP and theophylline that have previously been shown to stimulate secretion from the perfused gland produce a large increase in the degree of ouabain binding and the implications of this in the possible control of secretion rate are discussed.
Rate of egg penetration in vitro accelerated by T/t locus in the mouse
Authors: Olds‐Clarke P. , Carey J. E.
Published: June 2005

Spermatozoa from fertile mice heterozygous for tw32, a recessive lethal allele of the T/t locus, were compared to normal spermatozoa in a fertilization in vitro system. The rate of egg penetration following insemination in vitro was determined for epididymal spermatozoa from C57BL/6‐tw32 + mice and for epididymal spermatozoa from C57BL/6‐ + / + mice. At one hour after insemination, the mean of penetration ± standard deviation for spermatozoa from BL/6‐tw32 + mice was 20% ± 2.1 (109 eggs observed, 5 experiments), while the mean for spermatozoa from BL/6‐ +/+ mice was 1% ± 1.5 (107 eggs observed, 4 experiments). By five hours post‐insemination, the levels of egg penetration were not significantly different. These results suggest that tw32 increases the initial rate of egg penetration. Preliminary observations of spermmotility and sperm‐egg association at one hour post‐insemination in vitro do not support the hypothesis that this earlier penetration is due to improved sperm progress to the egg. Rather, the earlier penetration may be a result of changes in the timing of capacitation, the acrosome reaction, or sperm‐egg fusion. It is possible that the earlier penetration may play a role in the distortion of the transmission ratio of tw32.
Cytogenetics of the South American akodont rodents (Cricetidae). IV. Interspecific crosses between Akodon dolores × Akodon molinae
Authors: Merani Susana , Lizarralde Martha , Oliveira Daniel , Bianchi Nestor
Published: June 2005

Interspecific hybridization of Akodon molinae × Akodon dolores was obtained by crossing animals from our laboratory breeding colony. Sixteen pregnant females which produced a total of 86 Akodon hybrids were obtained from a total of 40 matings. The sex ratio in the hybrids was 2.58 males for each female. No clear explanation for this abnormal ratio can at the present time be given; however it cannot be ascribed to a phenomenon of intrauterine selection between sexes. The presence of natural hybrids has not been detected; therefore, the appearance of Akodon molinae × Akodon dolores hybrids is up to this moment a laboratory phenomenon.
Studies on oocyte maturation of the medaka, Oryzias latipes. VI. Relationship between the circadian cycle of oocyte maturation and activity of the pituitary gland
Authors: Iwamatsu T.
Published: June 2005

The relationship between pituitary activity and oocyte maturation was examined in Oryzias latipes (medaka), which has a circadian cycle of oviposition. Throughout the circadian cycle of oviposition, females possessed a population of large oocytes more than 800 μm in diameter that could mature in the presence of gonadotropin. Oocyte maturation was observed in vitro in females hypophysectomized between three and ten hours after the beginning of the light period with the number of maturing oocytes increasing as hypophysectomy was delayed. Although in vivo oocyte maturation was blocked by hypophysectomy within two hours after the beginning of the light period, it was restored by a single injection of synthetic or mammalian pituitary hormones (gonadotropic, corticotropic and thyrotropic hormones) within ten hours after hypophysectomy. Of these pituitary hormones, FSH, LH and TSH could induce in vitro maturation of isolated oocytes. Oocytes matured in vitro in the absence of exogeneous hormones if they were isolated nine or more hours after the onset of light. The present study indicates that the circadian cycle of maturation of Oryzias oocytes is controlled by the release of pituitary hormone between three and nine hours after the beginning of the light period.
Indirect nervous control of luminescence in the polynoid worm Harmothoe lunulata
Authors: Nicolas Marie‐ThèRèSe , Moreau Marc , Guerrier Pierre
Published: June 2005

Light responses were recorded in vitro from isolated elytra of Harmothoë lunulata following field or intraganglionic stimulation. Similar responses were evoked through bath application or microinjection of acetylcholine (ACh) at the level of the ganglion. Antimuscarinic but not antinicotinic inhibitors reversibly blocked these responses. In these conditions, when the nervous system is blocked, the preparation no longer respond to K+ ions depolarization nor to electrical field stimulation (depolarizing or hyperpolarizing currents). These new data strongly suggest that a cholinergic nervous system controls light production through muscarinic receptors which are not localized at the level of the photocyte and definitively rules out the possibility that propagation of the stimulus involves epithelial conduction. We propose that the activation occurs through relaying structures different from the epithelium. Calcium may be involved in the transmission process since inhibitors of its movements also block light response.
Alanine biosynthesis during starvation in skeletal muscle of the spiny dogfish, Squalus acanthias
Authors: Leech Anthony R. , Goldstein Leon , Cha Chung‐Ja , Goldstein Jonathan M.
Published: June 2005

The release of alanine by dogfish (Squalus acanthias) skeletal muscle was assayed in vivo and alanine biosynthesis was characterized in vitro. Amino acid analyses of blood drawn from dorsal aorta and caudal vein indicated that after one day of starvation only alanine was released by tail muscle in statistically significant amounts. Alanine continued to be released for the following two weeks of starvation but fell significantly after that. Pelvic‐findepressor muscles incubated in a physiological medium synthesized significant amounts of alanine. This synthesis was dependent on a source of added isoleucine (or leucine) but not glucose. Addition to the incubation medium of 3‐mercaptopicolinic acid, an inhibitor of phosphoenolpyruvate carboxykinase had no effect on alanie biosynthesis. Thus, release of alanine by dogfish skeletal muscle is similar to that in mammals, but factors regulating biosynthesis may be different in the two groups.
Analysis of the physical forces that influence the shape of chick somites
Authors: Packard David S. , Jacobson Antone G.
Published: June 2005

With experiments and measurements we support the hypothesis that chick somites are shaped by packing forces produced by increases in somite volumes. Volume measurements show that somites expand considerably during the period from initial segmentation to acquisition of the mature rectangular shape (as viewed from above). Anterior somites begin as roundish objects. Somite expansion flattens the intersomitic faces. Posterior somites emerge from a compressed segmental plate with the interface between somite and segmental plate already planar. In all somites, subsequent increase in volume causes expansion dorsally, ventrally and laterally. The dorso‐ventral expansion accompanies the increase in height of the neural tube. When a single somite is excised, neighboring somites or segmental plate fill in the available space. The bulging of somites into vacated spaces suggests the presence of compression which could be the product of previous increase in somite volumes. The pliability of somites is demonstrated with experiments that bend the trunk of the embryo to the left and right reversibly changing the shapes of the somites. Carbon marks placed in pairs in somites and in adjacent neural tube stay together; this suggests that somites do not move relative to the neural tube in response to the compressive forces. Segmental plates isolated without neural tube or notochord form long oval somites. In order to be shaped properly, somites must be in intimate association with, and probably bound to, the neural tube and also most likely the notochord.
α‐Ecdysone does not induce ovarian development in adult Aedes aegypti
Authors: Fuchs M. S. , Schlaeger D. A. , Shroyer C.
Published: June 2005

Previous findings have shown that vitellogenesis is initiated in non‐blood‐fed Aedes aegypti by injection of the insect steroid hormone ecdysterone. The precursor of ecdysterone, α‐ecdysone was assayed for its ability to induce ovarian development. Both the amount of vitellin deposited into ovarian follicles and the dopa decarboxylase activity were monitored. In contrast to ecdysterone, α‐ecdysone was negative with regard to both parameters. In addition, 22‐isoecdysone, previously reported to be active, was also shown to be ineffective. These findings suggest that the C20 hydroxylating mechanism necessary to convert α‐ecdysone to ecdysterone is absent in unfed females, but is activated by the blood‐meal.
Inhibition of estrous cyclicity in golden hamsters by melatonin administration on the day of proestrus
Authors: Andre Joel S. , Parrish John
Published: June 2005

Single injections of melatonin (25 micrograms) were administered to female hamsters, 15 minutes before lights‐out (14L:10D), during either the early diestrous (day 1) or proestrous (day 4) phase of the estrous cycle. Hamsters which received melatonin only on the evening of proestrus became anovulatory by three weeks of treatment, while those that were injected with melatonin during diestrus, or administered oil on either day 1 or 4, continued to exhibit normal estrous cycles. These results indicate that quartan injections of melatonin can suppress reproductive function in female hamsters, and that the effectiveness of the injections may be dependent upon the stage of the estrous cycle at which they are administered.
Comparative enzymology and physiological role of D‐lactate dehydrogenase from the foot muscle of two gastropod molluscs
Authors: Long George L. , Ellington W. Ross , Duda Timothy F.
Published: June 2005

D‐Lactate dehydrogenases from the foot muscles of the black abalone, Haliotis cracherodii, and the pulmonate snail, Helix aspersa, have been characterized. The D‐lactate dehydrogenase from H. cracherodii, which is found as a single, isoenzymic form, was purified to homogeneity. The enzyme in H. aspersa foot muscle is found as two distinct fast and slow migrating electrophoretic complexes of isoenzymes. The most abundant isoenzyme in the slow electrophoretic complex of H. aspersa was purified to homogeneity. The purified enzymes from the two organisms have similar physical and catalytic properties to one another and to other D‐lactate dehydrogenases, suggesting a close evolutionary relationship. Purified D‐lactate dehydrogenases from H. cracherodii and H. aspersa have molecular weights of approximately 80,000, as judged by meniscus depletion sedimentation equilibrium experiments, which correspond to a dimeric subunit organization. Kinetic studies show that the apparent Michaelis constant for pyruvate is 0.2–0.3 mM for the two purified enzymes as well as the partially purified fast isoenzymic complex from snail. Km values for D‐lactate are about ten times higher. Km values for α‐ketobutyrate are 4–10 mM for all three enzymes and Vmax is approximately 40–80% of that seen with pyruvate, suggesting that the enzymes may be physiologically important in dealing with α‐ketoacids in general. Km'S for NADH are all 10–20 μM, and those for NAD+ about 10‐fold greater. The most notable catalytic difference between the two enzymes is the presence and absence of substrate inhibition by pyruvate of the abalone and snail enzymes, respectively. This difference may reflect different physiological roles for the enzyme in the two organisms.
Role of neural crest in determining the numbers of pigment cells in the melanoid mutant of Ambystoma mexicanum Shaw
Authors: Sawada Soledad Rivera , Dalton H. Clark
Published: June 2005

Experiments are reported testing whether the primary control of chromatophore development under the influence of the melanoid gene (m) in the axolotl is exerted by factors intrinsic or extrinsic to the chromatoblasts of the neural crest. Melanoid animals differ from the wild type in having more melanophores, fewer xanthophores and no iridophores. The total number of chromatophores remains unchanged. This is interpreted as evidence of a common stem cell derivation of melanophores and xanthophores in the axolotl. Hanging drop explants of melanoid neural crest duplicate the skin chromatophore ratios. Chromatophore counts from epidermal vesicles consisting of neural crest and somatopleure in different genotypic combinations provide the ratios expected according to the genotype of the neural crest component. In reciprocal homotopic transplantations of neural crest between melanoid and wild type embryos, donor type pigment patterns develop. These studies show that the effect of gene m is mediated by factors intrinsic to the neural crest cells prior to their migration.
CO2 exchange in the blue crab, Callinectes sapidus (Rathbun)
Authors: Aldridge James B. , Cameron James N.
Published: June 2005

This study represents a first attempt to describe the pattern of carbon dioxide excretion in the gills of the blue crab, Callinectes sapidus. A computer simulation model was constructed, based on measurements of gill morphometry and blood carbon dioxide concentrations. Results of the simulation indicated that, although carbonic anhydrase is available in the gill epithelium for dehydration of HCO3−, it is probably not significantly involved in CO2 excretion. This conclusion was further supported by the observation that injection of a carbonic anhydrase inhibitor had no detectable effect on blood concentrations of CO2. Disequilibrium of the CO2‐HCO3− system is proposed as a significant factor in accounting for CO2 excretion.
The effect of ouabain on blood NaCl in the osmoregulating clam Rangia cuneata
Authors: Mangum C. P. , Henry R. P. , Simpson D. M.
Published: June 2005

Exposure of R. cuneata to exogenous ouabain is not lethal for several days. In both hypo‐ and hypersaline media, O2 uptake is uninhibited for periods up to 17 hr. Blood NaCl changes significantly, both before and after O2 uptake finally ceases. Changes in blood osmolality, however, are closely related to blood CaHCO3 and normal aerobic respiration.
Anaerobic rat heart: Mitochondrial role in calcium uptake and contractility
Authors: Shertzer Howard G. , Cascarano Joseph
Published: June 2005

In order to evaluate the manner by which fumarate enhances contractility in the anaerobic heart, we examined Ca++ movements in isolated heart mitochondria and in the isolated perfused heart. Our experiments showed that in isolated antimycin A plus cyanide treated mitochondria: (a) Ca++ uptake was promoted by electron transport generated by fumarate‐dependent oxidation of NADH, (b) Ca++ stimulated fumarate‐dependent oxidation of NADH, (c) the ratio of Ca++ uptake:NADH oxidized was 1.7 and (d) the Ca++ sequestered is transiently highly mobile and is rapidly released upon collapse of the membrane potential. In anaerobic hearts perfused with glucose plus fumarate, malate and glutamate Ca++ levels were the same as those in oxygenated hearts while in anaerobic organs perfused with or without glucose Ca++ content was appreciably lower. Succinate production in anaerobic heart perfusions was related to: (a) an increased retention of Ca++ by the heart, (b) a diminution in peak aortic pressure generated by cardiac contractions and (c) an increase in heart rate. The information obtained indicates that mitochondria have a capability for Ca++ movement which might be used physiologically, particularly in fumarate perfused anaerobic hearts, to assist the mechanism for contraction and relaxation of the heart.
Aldehyde dehydrogenase of the Mongolian gerbil, Meriones unguiculatus
Authors: Simpson Ford , Lindahl Ronald
Published: June 2005

The aldehyde dehydrogenase (Aldehyde:NAD(P) oxidoreductase E.C. 1.2.1.3 and 1.2.1.5) phenotype in several tissues of the Mongolian gerbil, Meriones unguiculatus, has been established. The tissue distribution of gerbil aldehyde dehydrogenase is similar to that of the rat, with liver possessing the majority of the aldehyde dehydrogenase activity. Male kidney and testis possess significantly more activity than female kidney and ovary. The substrate and co‐enzyme specificity of gerbil liver aldehyde dehydrogenase is also similar to that of rat and mouse liver. Gel isoelectric focusing resolves one major gerbil liver aldehyde dehydrogenase isozyme at pI 5.3. Mouse liver is resolved into two major isozymes at pIs 5.3 and 5.6 and rat liver aldehyde dehydrogenase into one major isozyme at pI 5.4. Gerbil liver aldehyde dehydrogenase is functional over a broad pH range with an optima at pH 9.0. Rat and mouse liver aldehyde dehydrogenase possess sharp pH optima at pH 8.5.
In vitro fertilization of two species of deer mouse eggs by homologous or heterologous sperm and penetration of laboratory mouse eggs by deer mouse sperm
Authors: Fukuda Y. , Maddock M. B. , Chang M. C.
Published: June 2005

Newly ovulated eggs from immature deer mice (Peromyscus maniculatus and P. polionotus) and mature laboratory mice (Mus musculus) treated with PMSG and HCG were inseminated in vitro with spermatozoa recovered from the cauda epididymidis of mature males. The time required for capacitation of deer mouse sperm in culture was estimated to be about two to five hours based on the dispersal of sperm agglutination and increase of sperm motility. The rate of sperm penetration through the zona pellucida of deer mouse eggs by homologous or heterologous sperm was relatively high (72–91%) but that of laboratory mouse eggs by deer mouse sperm was low (20–21%). After penetration through the zona pellucida, a high proportion of deer mouse eggs (79–93%) were fertilized by homologous or heterologous deer mouse sperm but no laboratory mouse eggs were fertilized by sperm of two species of deer mice. The zona pellucida was dissolved in a higher proportion of laboratory mouse eggs cultured with P. maniculatus (45%) than with P. polionotus sperm (3.4%), but this did not happen by incubation of deer mouse eggs with homologous or heterologous sperm. It seems that there is little difference in sperm penetration and fertilization between these two closely related species of deer mice but the reactions between the mouse eggs and deer mouse sperm are quite different.
The effect of collagen on the cyclic AMP content of embryonic somites
Authors: Kosher Robert A. , Savage Mary P.
Published: June 2005

Previous studies have demonstrated that collagen substrates stimulate in vitro somite chondrogenesis, and that agents that elevate intracellular cyclic AMP levels inhibit the ability of somites to respond to the inductive influence of collagen. In the present investigation, radioimmunoassay was utilized to compare the cyclic AMP content of somite explants cultured on purified Type I collagen substrates with control explants cultured on Millipore filters. During the period of culture, the cyclic AMP content of collagen‐treated explants is significantly lower than the cyclic AMP content of control explants. The cyclic AMP content of collagen‐treated explants is 66% of control values as early as one hour following the initiation of culture, and the cyclic AMP content of collagen‐treated explants remains lower than controls throughout the 3day culture period. The greatest difference in the cyclic AMP content of collagen‐treated and control explants is observed at the seventeenth hour of culture, at which time the cyclic AMP content of collagen‐treated explants is 56% of controls. These results combined with previous studies provide support for the hypothesis that collagen elicits a reduction in the cyclic AMP content of embryonic somites and that this reduction is necessary to trigger chondrogenic differentiation.
Direct evidence for formation of hybrid vesicles by fusion of plasma and outer acrosomal membranes during the acrosome reaction in boar spermatozoa
Authors: Russell Lonnie , Peterson Rudolph , Freund Matthew
Published: June 2005

A variety of treatment procedures was utilized to identify the origin and composition of the vesicles formed during the acrosome reaction of boar spermatozoa. Whether the acrosome reaction occurred spontaneously or was induced chemically the vesicles were hybrid vesicles composed of roughly equal proportions of plasma and outer acrosomal membranes.
Clarification of studies on the origin of thymic lymphocytes
Authors: Volpe E. Peter , Tompkins Robert , Reinschmidt Dana
Published: June 2005

The thesis that lymphocytes originate in situ by the direct transformation of epithelial cells within the thymic primordium in anurous frogs is untenable. On the contrary, in both the leopard frog and the African clawed toad, the lymphocytes that first appear in the embryonic thymus are derived from extrathymic lymphopoietc cells that invade the developing organ. The exact source of origin of the invading lymphopoietic cells remains problematic.
In vitro synthesis of RNA by Xenopus spermatogenic cells. I. Evidence for polyadenylated and non‐polyadenylated RNA synthesis in different cell populations
Authors: Kalt Marvin R.
Published: June 2005

Premeiotic and postmeiotic (haploid) gene expression during spermatogenesis in the anuran, Xenopus laevis, was studied by analyzing the accumulation of radioactively labelled cytoplasmic polyadenylated [poly (A +) ] and non‐polyadenylated [poly (A ‐) ] RNAs. Dissociated spermatogenic cells were labelled and maintained in an in vitro system capable of supporting cell differentiation. Labelled cells were separated by density gradient centrifugation into subpopulations enriched for individual spermatogenic stages. RNA was extracted and purified from each cell fraction, and separated into poly (A +) and poly (A ‐) species. Comparison of poly (A +) to non‐poly (A) radioactivity in cells labelled with tritiated uridine or adenosine demonstrated that (1) all cell fractions produced significant quantities of polyadenylated RNA relative to total RNA synthesis; and (2) that a cell fraction enriched for pachytene spermatocyte RNA contained up to 15% of total cytoplasmic and 35% of total polysomal RNA labelled as poly (A +) containing species. RNA was also characterized by sucrose density gradient centrifugation and polyacrylamide gel electrophoresis. All cell types showed typical poly (A ‐) peaks of 4S, 18S and 28S, corresponding to tRNA (4S) and rRNAs (18, 28S) respectively. Spermatids and spermatozoa had additional absorbance peaks at 13 and 21S which cosedimented with Xenopus oocyte mitochondrial rRNA. Patterns of incorporation of uridine and adenosine into poly (A +) RNA in all germ cell fractions tested were complex. In all cases, major areas of radioactivity were found in a broad band sedimenting between 6–17S. Spermatid fractions showed a prominent peak of incorporation at 6–8S, while pachytene cells also showed heavier poly (A +) peaks in the 17–25S region. A non‐polyadenylated RNA species sedimenting at 6–8S with a relatively rapid rate of turnover was also observed in spermatids. From these results it is concluded that synthesis of transfer, ribosomal, and putative messenger RNA species continues in spermatogenic cells throughout all but the very last stages of spermatogenesis in Xenopus.
Neural control of light emission in Photuris larvae: Identification of Octopamine‐Sensitive adenylate cyclase
Authors: Nathanson James A. , Hunnicutt Edward J.
Published: June 2005

Octopamine, a putative phenylethylamine neurotransmitter present in the firefly, has been found to be a potent stimulator of cyclic AMP synthesis in the larval light organ. In the same tissue, octopamine causes a small inhibition of phosphodiesterase activity. Because of the relatively simple anatomical relationships present in the larval light organ, compared with that of the adult, this preparation should offer an attractive model for studying the biochemistry of neurohumoral control of light emission.
Mouse embryo attachment to substratum and interaction of trophoblast with cultured cells
Authors: Glass Robert H. , Spindle Akiko I. , Pedersen Roger A.
Published: June 2005

Hatching, attachment, and trophoblast outgrowth of mouse embryos in vitro were examined as a model for implantation. Mouse embryos attached and grew out on glass cover slips that were partially covered with cultured mouse cells (L cells, liver cells, transformed JLS‐VII cells, and teratocarcinoma cells). Scanning electron microscopy showed that processes of these cells made contact with trophoblast, but there was no evidence of cell lysis or of phagocytosis of the cells by trophoblast. Time‐lapse cinematography showed that after contact the cultured mouse cells retracted from the trophoblast, which then spread into the areas vacated by those cells. This suggests a means by which the trophoblast gains entry into the endometrium without destruction of maternal cells.

Neuraminidase (100 or 250 units/ml) had no effect on attachment of mouse embryos to glass. However, attachment was inhibited by trypsin at concentrations of 0.25%, 0.025%, and 0.0025%. Treatment of early blastocysts with diazooxonorleucine, an inhibitor of glycoprotein synthesis, decreased the number of embryos hatching from the zona pellucida; treatment at the late blastocyst stage decreased hatching to a lesser extent. Among the late blastocysts that did hatch, the number forming trophoblast outgrowths was lower than in controls. These results suggest that glycoproteins may be of importance for embryo hatching, attachment, and outgrowth.
Mammalian lung development: The possible role of cell proliferation in the formation of supernumerary tracheal buds and in branching morphogenesis
Authors: Goldin Geoffrey V. , Wessells Norman K.
Published: June 2005

During the development of the lung, branching morphogenesis of the epithelium requires the presence of bronchial mesenchyme. Although it has been demonstrated that continuing morphogenesis is dependent upon growth through proliferation, there is no direct evidence to suggest that the specific pattern of branching is a consequence of differential mitotic activity which is influenced by the appropriate mesenchymal tissue. The induction of supernumerary buds in the tracheal epithelium of the mouse by transplantations of bronchial mesenchyme provides a means for analysing the role of cell proliferation in the formation of bronchial buds. We have addressed the problem by examining the ability of the tracheal epithelium, at different stages of development, to respond to bud induction by bronchial mesenchyme, and attempted to correlate this with the labeling index and 3H‐thymidine uptake in the trachea at the respective stages. It has been found that both the 11‐day‐old and 12‐day‐old tracheal epithelia initiate supernumerary buds in response to bronchial mesenchyme although the initiation in 12‐day‐old embryonic trachea occurred somewhat later than in the 11‐day‐old explants. The 13‐day‐old trachea failed to elicit buds after the tracheal mesenchyme had been stripped following treatment with 3% trypsin‐pancreatin. A decrease in cell proliferation in the tracheal epithelium (as revealed by autoradiography and scintillation counting following 5‐hour labeling with tritiated thymidine) between 11 and 13 days of development could contribute to these varying responses to bud induction. Further autoradiographic studies whereby the labeling index in the induced bud and the tracheal epithelium of the same explant have been compared, have revealed a continued high level of labeling in the branching bud and a concomitant decrease in labeling of the trachea. These data suggest that the bronchial mesenchyme either acts as a mitotic stimulator or provides conditions permissive to continued mitotic activity.
The gill arch of the mullet, Mugil cephalus. II. Modification in surface ultrastructure and Na,K‐ATPase content during adaptation to various salinities
Authors: Hossler Fred E. , Ruby John R. , McIlwain Thomas D.
Published: June 2005

The effect of salinity changes on the surface ultrastructure and Na, K‐ATPase content of the gill filament of mullent was determined using scanning electron microscopy and 3H‐ouabain binding. The number of ouabain binding sites/mg wet weight of tissue increased with increasing salinity. Mullet adapted to fresh water, or to salinities of 10, 26 and 45 g salt/liter exhibited ouabain binding capacities of about 1, 2, 4 and 5 pmoles ouabain bound/mg wet weight of tissue. Ouabain binding was strongly effected by ATP and KCI, whereas bound 3H‐ouabain was uneffected by the addition of unlabelled ouabain. Similarly, epithelial pores on the filament surfaces exhibited ultrastructural features which were indicative of the various salinities to which the fish were adapted. In fresh water, the pores were broad (average diameter 3‐6 μ) and shallow, and a cellular mass protruded from the pores above the epithelial surface. In 10 g salt/liter, the pores averaged 1–5 μ in diameter, were slightly deeper, and contained obvious, protruding cellular extensions. In 45 g salt/liter, the pores were narrower (average diameter 1–3 μ), considerably deeper, and exhibited fewer, less obvious cellular extensions in their interior. Because the pores likely represent the apical pits of ion secreting chloride cells and because the Na, K‐ATPase has been localized in chloride cells, these observations likely represent two different manifestations of the same process, adaption of chloride cells for osmotic regulation.
Mechanisms of ammonia and acid extrusion by the little skate, Raja erinacea
Authors: Evans David H. , Kormanik Gregg A. , Krasny Edward J.
Published: June 2005

The little skate (Raja erinacea) excretes ammonia and titratable acid at a rate of 6.37 and 40–95 μM. 100g‐1. hr‐1, respectively, at an external pH of 7.8 to 8.0. Transfer into Na‐ and K‐free artifical sea water does not alter the rate of ammonia efflux but reduces titratable acid efflux to zero. Addition of amiloride (10‐4M) to the external sea water does not alter the ammonia efflux but reduces the titratable acid efflux by 49%. Thus, while ammonia efflux is apparently not via Na (or K)/NH4 exchange, excretion of titratable acid is apparently via Na (or K)/H exchange.
Enzyme changes accompanying thermal acclimation in two species of pleurocerid snails
Authors: Pugh Charles R. , Ultsch Gordon R. , Lindahl Ronald
Published: June 2005

Goniobasis cahawbensis is a stream snail that experiences an annual temperature cycle. G. cochliaris is limited in distribution to springs, and their immediate vicinities, which are characterized by nearly constant annual temperatures. The present study sought to determine whether temperature dependent biochemical differences exist that might account for the differential distribution of these congeneric pleurocerid snails.

Eight enzymes were examined following acclimation to 10°, 17° and 24°C. No significant temperature dependent qualitative differences in enzyme phenotypes were demonstrable in either species by starch‐gel electrophoresis for malate dehydrogenase, glucose‐6‐phosphate dehydrogenase, phosphogluconate dehydrogenase, phosphoglucomutase, superoxide dismutase and acetyl and butyryl esterases. Significant quantitative differences were observed in three of these enzymes. G. cahawbensis cytosol malate dehydrogenase activity increased significantly with increasing acclimation temperature, while G. cochliaris malate dehydrogenase activity remained unchanged. The activities of glucose‐6‐phosphate dehydrogenase did not differ significantly between acclimation temperatures for either species; however, the overall activity of both enzymes was significantly higher for G. cochliaris. Appreciable levels of LDH activity were not demonstrable by electrophoresis or enzymatic assay.
The time and location of the acrosome reaction during sperm transport in the female rabbit
Authors: Overstreet J. W. , Cooper G. W.
Published: June 2005

Motile spermatozoa with lifted or absent acrosomal caps (“reacted acrosomes”) were observed by phase contrast microscopy exclusively in the oviduct of the rabbit reproductive tract during the first 16 hours post coitum (p.c.). They were first identified at six hours p.c. in flushings from the lower isthmus of the oviduct and were present in both the lower and upper isthmus two hours later. Motile spermatozoa with reacted acrosomes appeared in the lower ampulla (the site of fertilization) at ten hours p.c. Such spermatozoa were obtained from all regions of the oviduct at 12 and 16 hours p.c. but they always constituted a minority of the freely swimming spermatozoa recovered. The percentage of spermatozoa with activated motility was higher following the acrosome reaction, and their apparent swimming speeds were lower than those of intact spermatozoa. The role of ovulation in the induction of acrosome reactions was studied in females artificially inseminated per vaginam (AI), with or without the induction of ovulation, and in females mated either two hours before or two hours after ovulation. The proportion of motile spermatozoa with reacted acrosomes in the isthmus and ampulla of non‐ovulatory females 12 hours after AI was similar to their proportions in these regions 12 hours after mating or 12 hours after AI with induced ovulation. Four hours after delayed matings, i.e., two or six hours after ovulation, motile spermatozoa were confined to the tubal isthmus and none had undergone the acrosome reaction. These findings indicate that the products of ovulation and the endocrine changes associated with ovulation in the rabbit need not be directly involved in the induction of the acrosome reaction in vivo.
Neurites grow faster towards the cathode than the anode in a steady field
Authors: Jaffe Lionel F. , Poo Mu‐Ming
Published: June 2005

We explanted fragments of embryonic chick dorsal root ganglia on to polylysine coated glass and cultured them in a medium containing one unit of nerve growth factor plus enough methylcellulose to give viscosities from 0.01–3,000 poise. We allowed them to grow out in the absence of a field, and then selected explants with halos of neurites which were relatively dense, relatively symmetrical, and practically free of glial cells. These selected explants were then exposed to electrical fields of up to 140 mV/mm for some hours.

In media with viscosities of one poise or less, the field some times dragged the central cell mass of an explant towards the anode. However, in cases where the central cell mass did notmove, fields of 70–140 m V/mm induced that sector of each neurite halo which faced the cathode to grow out several times faster than the one facing the anode.

This neurite growth response showed little or no dependence upon viscosity (although it was inhibited by movements of the central cell mass). We speculate that it is mediated by lateral electrophoresis of the receptors for nerve growth factor along the plasma membranes of the neurites.
Possible adaptive significance of low red cell organic phosphates in crocodiles
Authors: Grigg Gordon C. , Gruca Margie
Published: June 2005

At similar conditions of temperature and PCO2 whole blood oxygen affinity of C. porosus is similar to that of its hemolysate as measured by other authors. Like other crocodilians so far measured, C. porosus, C. novaeguinea and C. johnstoni have low levels of red cell organic phosphates. A major role of CO2 in determination of oxygen affinity has been described previously for hemolysates of C. porosus and we confirm this in whole blood. Interestingly, however, O2 affinity may be less sensitive to pH. Low oxygen affinity, insensitivity of O2 affinity to organic phosphates, and low levels of red cell organic phosphates are features that C. porosus shares with mammals having low red cell 2,3‐DPG. These mammals share with C. porosus a capability for shortlived bursts rather than sustained activity.

At low levels of organic phosphate it is known for human blood that the fixed‐acid Bohr effect is much reduced. We propose that lowering red cell organic phosphates may be an adaptive strategy to reduce the fixed acid Bohr‐effect in animals subject to large changes in plasma pH. Such changes may be associated with a prolonged dive or other behavioural event which depends on anaerobic glycolysis.
The Wind‐Kessel effect of the bulbus arteriosus in trout
Authors: Farrell A. P.
Published: June 2005

Pressure/volume curves were determined for the bulbus arteriosus and ventral aorta. The curves show a high degree of compliance over the 40 to 60 cm H2O pressure range, a range that is similar to ventral aortic blood pressures in trout. Hypoxic, adrenergic and cholinergic treatments all altered the shape of the pressure/volume curves. Arterial blood flow is therefore depulsed in vivo and the extent of depulsation may be regulated.
Electrophoretic analyses of lactate dehydrogenase C4 in testes and vesicular glands of normal and male sterile translocation mice
Authors: Holmes Roger S. , Andrews Sandra , Jones Janet T.
Published: June 2005

Lactate dehydrogenase (LDH) C4 activity was observed in testis extracts from normal mice but was progressively reduced in mice carrying the male‐sterile translocations T31H, T32H, T37H, T38H, T40H and T42H, with no detectable activity being observed in the last two mice. None of the vesicular gland extracts from these male‐steriles showed LDH‐C4 activity, unlike normal mice. The differential LDH‐C4 activity in male‐sterile testes is interpreted as reflecting the varying stages of the spermatogenic defect during meiosis. In general, early meiotic defects exhibited no LDH‐C4 activity whereas late stage (usually after metaphase‐1 stage) defect animals exhibited some activity. The results also provide evidence for contaminating sperm being the source of normal vesicular gland LDH‐C4 activity.
The interaction of nerves of opposite regenerating polarity in fused newt forelimbs
Authors: Goshgarian Harry G.
Published: June 2005

Previous studies involving nerve interactions and limb regenerative processes were carried out on adult newts after their forelimbs were amputated through the distal radius and ulna and fused end‐to‐end. On the basis of limb regeneration results at the junction of the fused limbs, it was postulated that regenerating nerves from each limb (i.e., nerves of opposite polarity) would not invade the foreign territory of the contralateral limb if it were already normally innervated. A direct study of this nerve interaction, however, was not made in this earlier study. The present investigation was designed to obtain direct histological and electrophysiological evidence for the interaction of nerves of opposite regenerating polarity in fused newt forelimbs. The primary objective was to determine how the regenerating nerves would interact in the establishment of innervation territories—first, at the fusion zone, which represents the junction of the normal innervation territories of the nerves of each limb; and secondly, half way up one of the limbs, where interaction would occur in a territory normally innervated by only one of the regenerating nerves. The results showed that when nerves of opposite regenerating polarity approached one another at the junction of the fused limbs a discontinuation of axonal growth occurred; no indication of overlap of nerves into foreign territory was seen. When the nerves were allowed to interact within one of the fused limbs, however, an overlap of nerve fibers and a functional “double innervation” of that limb was demonstrated. These results are discussed in terms of possible mechanisms for the establishment of innervation territories in salamander limbs. The question of nerve‐muscle reinnervation specificity is also raised.
The first appearance of muscle spindles in the iliofibularis muscle of the frog during metamorphosis
Authors: Butler Richard
Published: June 2005

The iliofibularis muscle of the frog was studied histologically at different developmental stages during metamorphosis in order to determine when muscle spindles first appear. The earliest stage at which spindles were positively identified was stage XVIII, and they appear relatively complete as judged by their morphology. An analysis of the reports of variations in the numbers of neurons in frog spinal ganglia suggest that muscle spindles may in fact be induced as early as stage X.
Development of acetylcholinesterase during embryogenesis of the ascidian Ciona intestinalis
Authors: Meedel Thomas H. , Whittaker J. R.
Published: June 2005

We have characterized the embryonic muscle cell cholinesterase of the solitary ascidian, Ciona intestinalis (L.). The effects of selective enzyme inhibitors and the inhibition of enzyme activity at high concentrations of substrate suggest that the muscle cell enzyme is an acetylcholinesterase (E. C. 3.1.1.7). After gastrulation and before hatching, acetylcholinesterase activity increased 35‐ to 40‐fold; after hatching (18 hours postfertilization) this activity continued to increase, leveling off at about 36 hours of development. Histochemical observations showed that before hatching acetylcholinesterase was located principally in the muscle cells of the tail and, after hatching, it began to develop in cells of the adult musculature and brain. Inhibition of protein synthesis by puromycin and of RNA synthesis by actinomycin D, suggest that both protein and RNA synthesis were required for the increase in acetylcholinesterase activity observed in unhatched embryos. Although the continued increase in enzyme activity during embryonic development was sensitive to puromycin at all times tested, the actinomycin D sensitivity of this increase was restricted to a discrete time that was completed by about 11 hours of development.
Lizard and newt tail regeneration: A quantitative study
Authors: Baranowitz S. A. , Maderson P. F. A. , Connelly T. G.
Published: June 2005

Almost perfect fits of the Gompertz equation to the growth in length of tail regenerates in the lizard, Lacerta lepida, and the newt, Notophthalmus viridescens, were obtained. Comparison of certain parameters of the equation with published mitotic index data suggests that the Gompertz equation characterizes each system at least from the time that significant mitotic activity is first observed histologically. An objective method for comparing the regeneration periods of the two species is described and applied.

A unified hypothesis derived from consideration of properties of the Gompertz equation successfully accounts for the following phenomena reported, but previously unexplained, in the literature: (1) proximal amputations result in longer regenerates than do distal amputations; (2) proximal amputations elicit greater absolute rates of elongation (in mm/day) than do distal amputations; (3) the percent replaced of the length removed is rather constant, regardless of the absolute length regenerated; and (4) one of the parameters of the Gompertz equation appears to be lognormally distributed in a regenerating population. (See text for references.)

A computerized interactive graphical system for normalizing growth equations of individual regenerates and integrating the mathematical model with potential candidates for biological control factors is briefly described.
Ultrastructural changes in cells associated with interkinetic nuclear migration in the developing chick neuroepithelium
Authors: Nagele Robert G. , Lee Hsin‐Yi
Published: June 2005

Changes in fine structure of cells associated with interkinetic nuclear migration in the developing chick neuroepithelium were investigated. Interphase cells are elongated and span the entire thickness of the neuroepithelium. As cells round up in preparation for mitosis, they sever their contacts with the basement membrane, but retain their apical junctions. Meanwhile, microtubules lose their apico‐basal orientation and the apical microfilament bundle relaxes to allow broadening of the luminal surface. These changes in the cytoarchitecture together with an increased cytoplasmic viscosity may cause rounding of mitotic cells and their juxtaluminal position. Mitotic cells remain at the lumen from late prophase through early telophase. By late telophase, daughter cells start to elongate toward the base of the neuroepithelium. The ultrastructural changes during elongation recapitulate, in a reverse order, the events of rounding up in preparation for mitosis. Daughter cells are connected for some time after mitosis by a thread of cytoplasm. The thread is filled with microtubules representing a remnant of the spindle complex and has an electron‐dense midbody at about the middle of its length. During the final stage of separation of daughter cells, the thread is split at the level of the midbody.
Calcium‐induced Dehiscence of Cortical Granules in Xenopus laevis Oocytes
Authors: Hollinger T. G. , Dumont James N. , Wallace R. A.
Published: June 2005

Microinjection of 0.1 μg of Ca++ into Xenopus laevis oocytes induces breakdown of the cortical granules. The cortical granules disappeared in both full grown (Stage VI) and small growing (Stage IV) oocytes. Microinjection of Mg++, K+, or Na+ had no effect on cortical granules in either Stage IV or Stage VI oocytes. Small quantities (0.03 μg) of Ca++ induced dehiscence of the cortical granules only in proximity to the injection site.
Production of tetraploid and homozygous diploid amphibians by suppression of first cleavage
Authors: Reinschmidt Dana C. , Simon Stuart J. , Volpe E. Peter , Tompkins Robert
Published: June 2005

Tetraploid and genetically homozygous diploid Xenopus can be produced conveniently, in large numbers, by suppressing the first cleavage division of eggs through the application of hydrostatic pressure. The pressure‐induced disruption of the mitotic spindle during the first division of a diploid zygote of the African clawed toad results in a tetraploid embryo. A homozygous diploid embryo can be derived by inhibiting the first cleavage of a parthenogenetically activated haploid egg. Both tetraploid and homozygous diploid larvae are viable and successfully undergo metamorphosis.
Identification of luteinizing hormone‐releasing hormone (LH‐RH) in the brain and pituitary gland of a fish by immunocytochemistry
Authors: Schreibman M. P. , Halpern L. R. , Th. Goos H. J. , Margolis‐Kazan H.
Published: June 2005

For the first time immunoreactive luteinizing hormone‐releasing hormone (LH‐RH) is demonstrated in both the brain and pituitary gland of a teleost (Xiphophorus maculatus) using an immunoperoxidase procedure. It is specifically localized in the perikarya and their axons of the ventral telencephalon and nucleus lateralis tuberis and within and between the gonadotrops and within some cells of the pars intermedia. These immuno‐reactions are extinguished when antiserum to LH‐RH is preincubated with LH‐RH antigen but not with neurohypophysial hormones.