bluuebunny/crossref_metadata_2025 huggingface dataset:
Developmental expression and hormonal regulation of the nuclear 29 kDa juvenile hormone‐binding protein in Manduca sexta larval epidermis
Authors: Palli Subba Reddy , McClelland Scott , Hiruma Kiyoshi , Latli Bachir , Riddiford Lynn M.
Published: June 2005

We have utilized a high specific activity photoaffinity analog of methoprene, [3H]‐methoprene diazoketone (MDK), to study the developmental expression and hormonal regulation of the 29 kDa juvenile hormone (JH)‐binding protein. The 29 kDa MDK‐binding protein was detected in the epidermis of the feeding 4th and 5th instar larvae but decreased in abundance during the molts to the 5th instar and the pupa. This protein was also detected in day 1 pupal epidermis. Culturing of day 2 5th instar larval integument in the presence of 2 × 10−6 M 20‐hydroxyecdysone (20HE) caused a threefold decrease in the 29 kDa MDK‐binding protein. Presence of 3 × 10−6 M JH I prevented this loss. Allatectomy of molting 4th instar larvae after the critical period for JH for a larval molt resulted in the absence of the 29 kDa MDK‐binding protein in epidermis isolated 25 hr later or from either day 1 5th instar larvae or day 1 pupae. Application of 5 μ of JH I or methoprene at the time of allatectomy and every 12 hr thereafter until dissection was necessary for the presence of this protein in day 1 5th instar larval epidermis. Application of 5 μg of JH I on the day of wandering and the next day caused the appearance of the 29 kDa MDK‐binding protein in the epidermis of day 1 pupae formed by allatectomized larvae.
The behavior and cytoskeletal system of chick gastrula mesodermal cells on substrata coated with lines of fibronectin
Authors: Toyoizumi Ryuji , Shiokawa Koichiro , Takeuchi Shigeo
Published: June 2005

In order to investigate the mechanism of the formation of the mesodermal layer during chick gastrulation, we observed the behavior of fragments of mesodermal cells explanted and cultured on substrata coated with parallel lines of fibronectin (FN). We also examined the distribution of F‐actin, α‐actinin, and vinculin in explanted fragments by immunocytochemical methods noting particularly their distribution with respect to FN lines.

Explants of mesodermal cells flattened on FN‐coated substrata and then became elliptical with the major axis of the ellipse oriented along the FN lines and migrated along them. The peripheral cells of explants extended filopodia and lamellipodia which attached preferentially to FN lines and then contracted, pulling other mesodermal cells in explants along passively. Vinculin and α‐actinin in peripheral anchoring filopodia and lamellipodia co‐localized with the terminations of F‐actin bundles and with FN lines, suggesting that the peripheral cells were the moving force for explant translocation.

We propose based on these results that in vivo, peripheral cells of invaginated cell mass are guided by the known FN‐rich fibrous extracellular matrix on the basal surface of epiblast to move outwards; the rest linked to the peripheral cells are pulled away from the primitive streak to spread in tandem to form the mesodermal layer.
Regulation of ovarian steroidogenesis in vitro in the viviparous shark, Squalus acanthias
Authors: Tsang Paul C. W. , Callard Ian P.
Published: June 2005

We investigated the steroid biosynthetic capabilities of ovarian granulosa and thecal elements of the viviparous dogfish, Squalus acanthias. In this report we present evidence that granulosa cells secrete quantitatively important amounts of progesterone (P), testosterone (T) and estradiol‐17β (E), while theca has a more limited capacity to synthesize T and E. Ovarian granulosa cells were obtained from animals at each stage of gestation. After collagenase dispersion, an aliquot of 250,000 cells was incubated at 18°C in basal medium, containing Eagle's salts, glutamine, penicillin, streptomycin and adjusted with 136 mM sodium chloride and 350 mM urea. After a 4 hour incubation, the content of P, T, and E in medium was determined by radioimmunoassay. P was not detectable at any time, while E was present throughout the cycle, being maximal when gestation is three quarters complete (Stage C). T gradually increased from Stage B toward late pregnancy. In Stage C granulosa cells, E production increased in the presence of graded doses of T substrate. Also, a homologous pituitary extract (1/25 equivalents) and the calcium ionophore A23187 stimulated production of all 3 steroids. Using radioisotopes, granulosa cells showed a wide range of synthetic capacities. In Stage C thecal tissue, E production also increased in the presence of graded doses of T substrate, while pituitary extract only increased T. When granulosa and theca were recombined, in the presence of pituitary extract, P levels decreased with a corresponding increase in T, when compared to granulosa alone. These data suggest a possible interaction between granulosa and theca for steroid biosynthesis. They further indicate that granulosa cells alone have the capacity to synthesize P, T, and E, without any input from theca.
Short‐term effects of triiodothyronine on the bowfin, Amia calva (holostei), and the lake char, Salvelinus namaycush (teleostei)
Authors: Ballantyne J. S. , John T. M. , Singer T. D. , Oommen O. V.
Published: June 2005

To assess the role of triiodothyronine (T3) in mediating short‐term changes in metabolism, such as those occurring in circadian patterns, we examined the effects of intraperitoneal injection of T3 on the oxidation of substrates by isolated mitochondria from liver of the bowfin, Amia calva, and red muscle and liver of the lake char, Salvelinus namaycush. Selected enzymes were measured in red muscle and liver of the lake char. Three hours after intraperitoneal injection of T3, oxidation of some substrates by mitochondria isolated from the liver of the bowfin was reduced. Similar treatment had no effect on substrate oxidation in liver mitochondria isolated from lake char. Oxidation of substrates by lake char red muscle mitochondria was stimulated by T3 injection. Citrate synthase levels were increased in red muscle suggesting that changes in enzyme activity may be in part responsible for the short‐term mitochondrial responses to T3 injection.
Oxidative metabolism in thermogenic tissues of the swordfish and mako shark
Authors: Ballantyne J. S. , Chamberlin M. E. , Singer T. D.
Published: June 2005

Mitochondria isolated from the heater organ of the swordfish Xiphias gladius and the warm lateral red muscle of the mako shark Isurus oxyrinchus display respiratory control, indicating that uncoupling of oxidative phosphorylation is not important in heat production. The mitochondria of the swordfish heater organ resemble those of mammalian brown adipose tissue in their substrate preferences, oxidizing pyruvate plus malate, palmitoyl carnitine, and α‐glycerophosphate at high rates. The high hexokinase levels in the heater organ indicate exogenous glucose is an important energy source. The high activity of cytosolic α‐glycerophosphate dehydrogenase and the high rates of mitochondrial oxidation of α‐glycerophosphate indicate that cytosolic redox is balanced via the α‐glycerophosphate cycle. Calcium stimulates mitochondrial α‐glycerophosphate oxidation, and it is proposed that calcium released from the sarcoplasmic reticulum may act as the signal coupling enhanced rates of substrate oxidation with calcium transport. Based on mitochondrial respiration rates, heat generation by the intact heater organ was calculated. Complete oxidation of glucose produces heat at a greater rate than oxidation of lipids. Nevertheless, oxidation of either substrate could produce sufficient heat to maintain tissue temperature 10°C above ambient at 20°C.

The mitochondria from the red muscle of the mako shark oxidize pyruvate plus malate, glutamine, glutamate, proline, and β‐hydroxybutyrate at high rates. Palmitoyl carnitine was not oxidized. The respiration rates are similar to those described for mitochondria isolated from “cold” muscle of other elasmobranchs. Therefore, it does not appear that mako shark red muscle mitochondria are specialized for thermogenesis.
Leydig cell renewal in testes of seasonally breeding animals
Authors: Hardy Matthew P. , Sprando Robert L. , Ewing Larry L.
Published: June 2005

Annual variations of androgen secretion and Leydig cell number occur in seasonally breeding animals: herein we review comparative observations on two widely divergent species, the salamander and hamster. Based on our laboratory studies in the hamster, we conclude that Leydig cell numbers increase during testicular recrudescence through a combination of differentiation of mesenchymal cell precursors and Leydig cell division. Secretion of androstane‐3α, 17β‐diol, a 5α‐reduced androgen, occurs transiently during the seasonal cycle and may be a characteristic of differentiating Leydig cells.
Environmental predictability and control of gonadal cycles in birds
Authors: Wingfield John C. , Hahn Thomas P. , Levin Rachel , Honey Pulmu
Published: June 2005

In most vertebrates, information from the external environment is used to regulate secretion of gonadotropins and thus time gonadal maturation in anticipation of the breeding season. These environmental factors provide “predictive” information in both the long term (initial predictive) and short term (supplementary), are integrated by the central nervous system, and are then transduced into neuroendocrine and endocrine control components. We apply the constancy/contingency model of predictability to breeding data from several avian species to derive a potential unifying hypothesis to explain how these environmental factors are integrated to regulate gonadal maturation. Predictability (Pr) is a function of varying degrees of constancy (C, the habitat is predictable because it is always the same) or contingency (M, the habitat is predictable in the degree of change from season to season). Thus, although variations in Pr provide useful information for timing gonadal maturation and regression, changes in the contributions of C and M to Pr (i. e., the ratio, M/C) provide even more useful information. It is proposed that the degree to which individuals integrate initial predictive and supplementary information to regulate secretion of gonadotropins, and thus time gonadal maturation and onset of breeding, is a function of the ratio of M to C for any given Pr value. When Pr is not significant (i. e., the environment is unpredictable), then only supplementary factors may be useful for timing breeding. Hypotheses generated by this approach are easily testable. Furthermore, this method could be applied to all vertebrates, and perhaps other organisms, and may provide a unifying framework to investigate the mechanisms by which proximate environmental factors regulate reproductive function in general.
Developmental regulation of ecdysteroid receptors in the nervous system of Manduca sexta
Authors: Fahrbach Susan E.
Published: June 2005

The technique of steroid hormone autoradiography has been used to study the cellular distribution of ecdysteroid binding sites in the ventral nervous system of the tobacco hornworm moth, Manduca sexta. The ligand was 26‐[125I]iodoponasterone. Tissue was examined from the subesophageal ganglia, thoracic ganglia, and abdominal ganglia of larvae at two times during the larval‐pupal transition: the 2nd day of wandering and the prepupal stage. The patterns of neuronal binding seen were compared with those found in earlier autoradiographic studies of hormone binding in tissue sampled on the 1st day of wandering, in the pharate adult, and in the 4‐day‐old moth (Fahrbach and Truman, '89). The pattern of binding was reproducible but dependent upon developmental stage: whereas only a subset of neurons exhibited nuclear accumulation of radiolabeled ecdysteroids on the 1st day of wandering, less than 24 hours later nearly every neuron in the ventral nervous system was labeled. A limited pattern of binding, however, was seen again in the prepupal nervous system. Thus, the insect nervous system is able to use a single hormone both as a general cue for metamorphic development and as a signal targeted to stage‐specific subsets of neurons by alternating periods of ubiquitous expression of receptor with periods during which the capacity to bind the steroid hormone is highly restricted.
Development of spinal motor networks in the chick embryo
Authors: O'Donovan Michael , Sernagor Evelyne , Sholomenko Gerald , Ho Stephen , Antal Miklos , Yee Wayne
Published: June 2005

We have examined the cellular and synaptic mechanisms underlying the genesis of alternating motor activity in the developing spinal cord of the chick embryo. Experiments were performed on the isolated lumbosacral cord maintained in vitro. Intracellular and whole cell patch clamp recordings obtained from sartorius (primarily a hip flexor) and femorotibialis (a knee extensor) motoneurons showed that both classes of cell are depolarized simultaneously during each cycle of motor activity. Sartorius motoneurons generally fire two bursts/cycle, whereas femorotibialis motoneurons discharge throughout their depolarization, with peak activity between the sartorius bursts. Voltage clamp recordings revealed that inhibitory and excitatory synaptic currents are responsible for the depolarization of sartorius motoneurons, whereas femorotibialis motoneurons are activated principally by excitatory currents. Early in development, the dominant synaptic currents in rhythmically active sartorius motoneurons appear to be inhibitory so that firing is restricted to a single, brief burst at the beginning of each cycle.

In E7‐E13 embryos, lumbosacral motor activity could be evoked following stimulation in the brainstem, even when the brachial and cervical cord was bathed in a reduced calcium solution to block chemical synaptic transmission. These findings suggest that functional descending connections from the brainstem to the lumbar cord are present by E7, although activation of ascending axons or electrical synapses cannot be eliminated.

Ablation, optical, and immunocytochemical experiments were performed to characterize the interneuronal network responsible for the synaptic activation of motoneurons. Ablation experiments were used to show that the essential interneuronal elements required for the rhythmic alternation are in the ventral part of the cord. This observation was supported by real‐time Fura‐2 imaging of the neuronal calcium transients accompanying motor activity, which revealed that a high proportion of rhythmically active cells are located in the ventrolateral part of the cord and that activity could begin in this region. The fluorescence transients in the majority of neurons, including motoneurons, occurred in phase with ventral root or muscle nerve activity, implying synchronized neuronal action in the rhythm generating network.

Immunocytochemical experiments were performed in E14‐E16 embryos to localize putative inhibitory interneurons that might be involved in the genesis or patterning of motor activity. The results revealed a pattern similar to that seen in other vertebrates with the dorsal horn containing neurons with γ‐aminobutyric acid (GABA)‐like immunoreactivity and the ventral and intermediate regions containing neurons with glycine‐like immunoreactivity.
Changes in monoamine transmitter concentration in freshwater mussel tissues
Authors: Dietz Thomas H. , Wilson John M. , Silverman Harold
Published: June 2005

Freshwater mussels were analyzed for biogenic amine transmitter substances in gill tissue, suprabranchial nerve and blood. Gill tissue from normal pondwater‐acclimated mussels contained significant amounts of monoamine neurotransmitter substances. In comparison with the suprabranchial nerve the gill tissue contained 42% of the dopamine, 7% of the serotonin and 490% of norepinephrine. Exposing the animals to deionized water (salt‐depleted) resulted in a loss of transmitter substances from gill tissue, but serotonin reduction was modest. The mussel gill tissue content of serotonin and the precursor tryptophan was regulated at nearly constant levels. Serotonin is an important transmitter substance in mussels and the many functions it controls, including sodium transport regulation, would depend on its continued presence.
External CO2 levels influence energy yielding metabolic pathways under hypoxia in the leech, Hirudo medicinalis
Authors: Hildebrandt Jan‐Peter
Published: June 2005

Medicinal leeches, Hirudo medicinalis L., were exposed to hypocapnic (nominal pCO2 0.0 kPa) or hypercapnic (pCO2 1.3 kPa) hypoxia (pO2 2.0 kPa) for up to 4 days. Changes in blood concentrations and tissue content of organic acids were measured.

In the early phase of hypercapnic hypoxia leeches accumulated mainly succinate, and the normally high malate concentrations in blood and tissue were reduced concomitantly. Between 2 and 24 h of hypoxia the animals started to produce propionate which is the major end‐product of this type of hypoxia. Only low concentrations of lactate were found in blood and tissue. During the initial phase of hypocapnic hypoxia an accumulation of succinate was also observed, but at a higher rate than during hypercapnic hypoxia. Subsequently, propionate was also produced. Between 24 and 48 h of hypocapnic hypoxia the concentrations of succinate in blood and tissue decreased rapidly and lactate appeared as an end‐product of anaerobic metabolism.

The results indicate that, in leeches under “environmental” hypoxia, the external concentration of carbon dioxide affects the pathway of carbohydrate metabolism resulting in either succinate/propionate production or in lactate accumulation. © 1992 Wiley‐Liss, Inc.
Purification and characterization of acidic alpha‐D‐mannosidase from the hepatopancreas of the shrimp Penaeus monodon (Crustacea: Decapoda)
Authors: Chuang Nin‐Nin , Yang Bei‐Chia , Lin Kung‐Shih
Published: June 2005

Acidic alpha‐D‐mannosidase purified from the hepatopancreas of Penaeus monodon is pentameric, with a Mr 251,000 as estimated by size‐exclusion FPLC on a SuperoseTM 12, and retains a hydrophobic domain, being stable to heating at 65°C for 1 h. The specific activity of the purified enzyme is 1,923 units/mg of protein. After polyacrylamide gel electrophoresis under denaturing conditions, the purified acidic alpha‐D‐mannosidase from shrimp was found to consist of a single homogeneous type of monomer of Mr 51,000. The purified enzyme has an isoelectric point of 4.4 ± 0.1 and becomes more alkaline after the removal of either sialic acid or phosphate groups. The apparent Km value of alpha‐D‐mannosidase from shrimp hepatopancreas with 4‐methylumbelliferylalpha‐D‐mannopyranoside as substrate is 243 μM. © 1992 Wiley‐Liss, Inc.
Intracellular free magnesium in the muscle of an osmoconforming marine invertebrate: Measurement and effect of metabolic and acid‐base perturbations
Authors: Doumen C. , Ellington W. R.
Published: June 2005

Dissociation constants for MgATP [Kd(MgATP)] were measured with the combined techniques of spectrophotometry using the metallochromic dye, Antipyrylazo III, and phosphorus nuclear magnetic resonance (31P‐NMR) spectroscopy. Values of the Kd(MgATP) were dependent on pH, ionic strength, and the relative concentrations of competing and noncompeting ions. A model solution was constructed simulating the cytoplasm of the muscle of the horseshoe crab, Limulus polyphemus. Using this model solution, Kd(MgATP) values were determined. In addition, the acid dissociation constants (Ka's) for inorganic phosphate, ATP and MgATP were determined by 31P‐NMR. Free Mg+2 concentrations ([Mg+2]i) were estimated from 31P‐NMR spectra of superfused bundles of L. polyphemus muscle fibers based on the difference in chemical shift of the γ and β‐ATP resonances using Kd(MgATP) values corrected for prevailing intracellular pH (also estimated from spectra). The [Mg+2]i in L. polyphemus muscle was around 1,200 μM. Metabolic perturbations (anoxia, metabolic poisons) and experimental acidosis (hypercapnia) had no significant effect on [Mg+2]i but did alter the fraction of the total ATP pool complexed with Mg+2. Free magnesium is not in thermodynamic equilibrium, and thus it appears that [Mg+2]i is stringently regulated in L. polyphemus muscle. © 1992 Wiley‐Liss, Inc.
Histochemical identification and behavior of quail primordial germ cells injected into chick embryos by the intravascular route
Authors: Nakamura Masao , Yoshinaga Kazuya , Fujimoto Toyoaki
Published: June 2005

The behavior of quail primordial germ cells (PGC) after injection into chick embryos by the intravascular route was examined. The quail (donor) PGC, taken from the bloodstream of quail embryos (recipient) at stage 13–14, were injected into the vitelline vessels of chick embryos (recipient) at stage 15. In the recipient embryos, the PGC of the quail and the chick were histochemically distinguished by a double‐staining technique involving a lectin, from Wistaria floribunda (WFA) and the PAS reaction. One day after injection, quail PGC appeared in the prospective gonadal region of recipient chick embryos, being localized among the recipient chick PGC. This result indicates that a staining technique specific for WFA lectin is useful for identification of quail PGC and that quail PGC can be transferred by a vascular route for the production of germline chimeras. © 1992 Wiley‐Liss, Inc.
The pupillary system of noctuid moth eyes: Dynamic changes in relation to control of pupil size
Authors: Nordtug Trond , Melø Thor Bernt
Published: June 2005

Eye pupil‐size changes, in response to repetitive ON‐OFF light stimulation, of 3 species of noctuid moths have been observed by infrared reflection photometry. For moderate ON stimulus intensities (2.5·109 quanta·cm−2·s−1), eye reflectance changed exponentially with time, in both the ON and OFF phases. For low ON stimuli (2.5·108 quanta·cm−2·s−1), however, the dark adaptation response in the OFF phase was composed of an initial exponential and a subsequent linear term. For repetitive low‐intensity ON‐OFF stimuli, the response amplitude changed in a diurnal way. The shape of the response to each ON‐OFF stimulus was, however, independent of diurnal time. Finally, in eyes that were spontaneously entering a light‐adapted state, pure exponential dark adaptation was elicited by intense light pulses. It is suggested that the substances controlling light and dark adaptation are interrelated. The substances constitute a chemical cycle running at constant speed, in the absence of light, and the substance causing pigment dispersion (light adaptation) is a photoproduct of the other substance. The concentration of the substance causing pigment contraction (dark adaptation) is controlled by the rate of the back reaction, which is composed of an exponential term, related to accumulation of the photoproduct during light stimulation, and a constant term, due to the speed of the cycle. The cycle speed is subject to diurnal changes. © 1992 Wiley‐Liss, Inc.
Intra‐ and extra‐cellular sources of T3 binding to putative thyroid hormone receptors in liver, kidney, and gill nuclei of immature rainbow trout, Oncorhynchus mykiss
Authors: MacLatchy D. L. , Eales J. G.
Published: June 2005

The sources of extracellular and intracellular 3,5,3′ ‐triiodo‐L‐thyronine (T3) binding to putative thyroid hormone receptors in liver, kidney, and gill nuclei were determined in vivo for immature rainbow trout at 12°C. Both [131I]T3 and [125I]T4 were injected intraperitoneally, the plasma and tissues were examined at isotopic equilibrium at 20 h, and the proportions of intracellular [125I]T3 and extracellular [131I]T3 saturably bound in the nucleus were determined. Comparable total amounts of T3 were saturably bound in the nuclei of liver (7.2), kidney (8.0), and gill (9.7 moles × 10−13 .mg DNA−1), but the percentage of nuclear T3 generated within the target cell was greater for gill (76%) than for liver (50%) and kidney (28%). Both gill and liver possess a low Km T4 5′monodeiodinase which could be responsible for the high proportion of the nuclear T3 generated within those tissues. © 1992 Wiley‐Liss, Inc.
Ganglia implantation as a means of supplying neurotrophic stimulation to the newt regeneration blastema: Cell‐cycle effects in innervated and denervated limbs
Authors: Goldhamer David J. , Tomlinson Bruce L. , Tassava Roy A.
Published: June 2005

Regulation of blastema cell proliferation during amphibian limb regeneration is poorly understood. One unexplained phenomenon is the relatively low level of active cell cycling in the adult newt blastema compared to that of larval axolotls. In the present study, we used ganglia implantation as a means of “superinnervating” normally innervated adult newt blastemas to test whether blastema cell subpopulations are responsive to nerve augmentation. The effectiveness of implanted ganglia to provide neurotrophic stimulation was demonstrated in denervated blastemas. Blastemas implanted with 2 dorsal root ganglia and simultaneously denervated 14 days after amputation exhibited control levels of cell cycle activity 6 days later, as measured by 3H‐thymidine pulse labeling. Denervated blastemas that were sham‐operated or implanted with pituitary glands exhibited cell‐cycle declines similar to those of denervated blastemas without implanted ganglia. Thus, 2 implanted ganglia provide neurotrophic stimulation equivalent to that of the normal nerve supply. Dorsal root ganglia implanted into normally innervated blastemas, which should effectively double neurotrophic activity to the blastema, had no effect on cell‐cycle activity; innervated blastemas implanted with ganglia for 6 days exhibited pulse labeling indices similar to those of normally innervated blastemas. These data indicate that neurotrophic stimulation is not normally limiting in inner‐vated limbs, and that some other factor, whether extrinsic or intrinsic to blastema cells, accounts for the relatively low level of active cell cycling in the adult newt blastema. © 1992 Wiley‐Liss, Inc.
Partial purification and some chemical properties of the sperm chemoattractant from the forcipulate starfish Pycnopodia helianthoides (Brandt, 1835)
Authors: Punnett Thomas , Miller Richard L. , Yoo Bong‐Hee
Published: June 2005

The sperm attractant of the forcipulate starfish Pycnopodia helianthoides has been isolated by sea water extraction from ripe ovaries. After concentration and purification by adsorption and desorption using an Amberlite resin followed by gel filtration chromatography, the most active fractions have been further purified by reverse‐phase and hydrophobic‐interaction chromatography. A relative purification of 2 × 105 was obtained. Exposure of the partially purified attractant to temperature extremes and enzymes reveals that the molecule is heat and freeze‐thaw stable and that it is degraded by the proteases trypsin, chymotrypsin, and pronase. Four different procedures used to determine molecular size produce the same estimate of about 12 kD. The attractant is retarded during Sephadex G‐25 chromatography and does not run as a tight band on sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE). These results suggest that the sperm attractant of this starfish is a small protein. © 1992 Wiley‐Liss, Inc.
Hormonal control of sulfate uptake by branchial cartilage of coho salmon: Role of IGF‐I
Authors: McCormick Stephen D. , Tsai Peter I. , Kelley Kevin M. , Nishioka Richard S. , Bern Howard A.
Published: June 2005

The direct hormonal control of sulfate uptake by cartilage matrix of coho salmon was examined by exposing branchial cartilage to 1 μCi · ml−1 35SO4 for 48 hours at 15°C in a defined medium. Sulfate uptake occurred primarily in cartilage (rather than bone) and the amount of specific uptake was similar in epibranchial and ceratobranchial cartilages. Intact and hypophysectomized coho salmon starved for 22 days had equivalent in vitro sulfate uptake, which in both cases were 30% of the uptake seen in branchial cartilage of fed, intact controls. In branchial cartilage from starved coho salmon, in vitro exposure to recombinant bovine insulin‐like growth factor I (rbIGF‐I) at 1, 10, 100, and 1,000 ng · ml−1 caused a dose‐dependent increase in sulfate uptake, with a maximum 3‐fold increase over control at 1,000 ng · ml−1 rbIGF‐I. Coho salmon insulin (1, 10, 100, and 1,000 ng · ml−1) resulted in a maximum 30% increase in sulfate uptake at the highest dose. Growth hormone and triiodo‐L‐thyronine had no direct effect on in vitro sulfate uptake. The results indicate that IGF‐I has direct effects on coho salmon cartilage and may be an important regulator of growth in salmon and other teleosts. © 1992 Wiley‐Liss, Inc.
Effects of human insulin‐like growth factor‐I on release of growth hormone by rainbow trout (Oncorhynchus mykiss) pituitary cells
Authors: Pérez‐Sánchez J. , Weil C. , Le Bail P.‐Y.
Published: June 2005

A recombinant human IGF‐I (rhIGF‐I) was applied to primary cultures of rainbow trout pituitary cells. In wells containing 3 × 104 and 6 × 104 cells/well, rhIGF‐I inhibited basal GH release both in short (6 h) and long (12 and 24 h) exposures. The decline in GH release was dose‐dependent over the range of 0.01 and 100 mM. The combination of rhIGF‐I and low concentrations of synthetic somatostatin14 (SRIF) enhanced the inhibitory effect of rhIGF‐I in an additive manner. Any appreciable effect of rhIGF‐I on PRL release was not evidenced. To our knowledge, this report demonstrates for the first time the participation of IGFs on the inhibitory component of fish GH regulation. © 1992 Wiley‐Liss, Inc.
Chromosome assignments of the human TNF p55 and p75 receptor genes
Authors: Brownell Elise , Ranges G. E. , Sarr T. , Fiorentino L. , Godfrey M. , Pekar S. , Hart J. , Kamarck M. , Rae P. M. M. , Ruddle F. H. , Bayney R.
Published: June 2005

At least two different receptor molecules have been described that are capable of binding tumor necrosis factor alpha, a cytokine that plays an important role in inflammation and antitumor activity. Comparative analyses at the nucleotide sequence level suggest that these receptors are members of a newly defined protein family that also includes human and rat nerve growth factor receptors. In this study, we determine the chromosome assignments of the human TNF alpha receptor genes, one of which may have evolved as part of a conserved Hox locus‐containing chromosome segment. © 1992 Wiley‐Liss, Inc.
Atrial natriuretic peptide clearance receptors in trout: Effects of receptor inhibition in vivo
Authors: Duff Douglas W. , Olson Kenneth R.
Published: June 2005

Inactivation of circulating atrial natriuretic peptides (ANP) by specialized clearance (C) receptors has been characterized in mammals but has not been examined in fish. In the present study arterial blood pressure, urine flow, and urine electrolytes were measured in chronically cannulated rainbow trout, Oncorhynchus mykiss, during infusion of the specific C receptor inhibitor, SC‐46542. C receptor inhibition decreased blood pressure and pulse pressure, increased heart rate and urine flow, but did not affect urinary electrolyte concentrations. These responses are consistent with those produced by exogenous ANP administration and indicate that: (1) trout possess C‐type receptors capable of ANP inactivation, and (2) ANP‐like molecules are continuously released and metabolized by trout in vivo. Phosphoramidon, an inhibitor of neutral endopeptidase, did not enhance the SC‐46542 response, indicating that C receptors predominate in ANP inactivation in these fish. © 1992 Wiley‐Liss, Inc.
Prostaglandin synthesis in vitro by ovarian follicles and extrafollicular tissue of the viviparous guppy (Poecilia reticulata) and its regulation
Authors: Venkatesh B. , Tan C. H. , Lam T. J.
Published: June 2005

Developmental changes in the prostaglandin synthesising potential in vitro of follicles of the viviparous guppy during oocyte growth and gestation were investigated. Basal production of PGE and PGF was low in follicles during oocyte growth, maturation, and early gestation, increased in mid and late gestation, and declined at postparturition. A similar pattern was also observed in the production of these prostaglandins by follicles at different developmental stages in the presence of exogenous arachidonic acid. Extrafollicular (EF) ovarian tissue of the guppy synthesised large amounts of PGE and PGF spontaneously as well as from exogenous arachidonic acid. Late gestation follicles and EF tissue incorporated 14C‐arachidonic acid into PGE2α, PGF2α, 6‐keto‐PGF1α, and monohydroxyeicosatetraenoic acids. The ability of mid and late gestation stage follicles to synthesise large amounts of prostaglandins suggests that it may be related to ovulation and parturition. Extrafollicular tissue may also play a role in the induction of ovulation and parturition. Dibutyryl cAMP inhibited prostaglandin production by late gestation follicles and EF tissue in a dose‐dependent manner. Although the physiological significance of the effect of cAMP is not known, it is possible that high levels of cAMP during oocyte maturation may inhibit ovulation of mature oocytes by inhibiting prostaglandin synthesis. Cortisol (25 and 250 ng/ml) inhibited PGE and PGF production by late gestation follicles. Both the doses of cortisol tested also inhibited PGE production by EF tissue. However, only the higher dose was effective in inhibiting PGF production by EF tissue. Ovarian steroids such as estradiol‐17β, testosterone, 17α,20β‐P, and progesterone (5 and 50 ng/ml) had no effect on PGE and PGF production by late gestation follicles and EF tissue. Our earlier studies on serum steroid profile in the guppy have shown that cortisol levels decline at periparturition. It is possible that this decline may remove the block on prostaglandin synthesis, leading to increased synthesis of prostaglandins, which are presumably involved in the induction of ovulation and parturition. © 1992 Wiley‐Liss, Inc.
Changes in growth hormone and prolactin messenger ribonucleic acid levels during seawater adaptation of amago salmon (Oncorhynchus rhodurus)
Authors: Yada Takashi , Kobayashi Tooru , Urano Akihisa , Hirano Tetsuya
Published: June 2005

To examine the changes in secretion of growth hormone (GH) and prolactin (PRL) with reference to their osmoregulatory roles, changes in pituitary mRNA levels and plasma concentrations of these hormones were examined during seawater adaptation in silvery juveniles (smolts) and precociously mature males (dark parr) of amago salmon (Oncorhynchus rhodurus). Transfer to seawater increased plasma sodium levels in both smolts and dark parr. Smolts adjusted their plasma sodium to the level associated with seawater‐adaptation (165 mEq/liter) within 3 days, whereas no adjustment was seen in dark parr; the latter failed to survive in seawater for more than 3 days. In smolts, plasma GH levels increased significantly 1 day after transfer, whereas there was no significant change in dark parr. An increase in GH mRNA levels was observed in smolts in association with increased plasma GH, whereas there was no change in dark parr. In contrast, a reduction in plasma PRL levels was consistently observed in both smolts and dark parr after transfer to seawater. However, there was no significant change in PRL mRNA levels in either smolts or dark parr. These results suggest that both gene expression and release of GH are activated by seawater transfer only in smolts with adequate seawater adaptability, whereas PRL gene expression is decreased after sea‐water adaptability. © 1992 Wiley‐Liss, Inc.
The role of the adrenal glands in regulating onset of winter fur growth in mink (Mustela vison)
Authors: Rose Jack , Sterner Mauritz
Published: June 2005

ABSTRACT The role of the adrenal glands in regulating onset of winter fur growth in mink was investigated in long‐term adrenalectomized animals. Bilateral adrenalectomy of adult female standard dark mink between June 23 and July 11, 1990, initiated onset of winter fur growth approximately 6 weeks earlier than controls. One month following completion of the winter fur growth in adrenalectomized mink, molting and growth of a new coat was observed. The type of pelage that grew as a result of the second growth wave was less dense than the normal summer or winter fur. However, this renewed hair growth suggests that adrenal hormones not only inhibit the onset of winter fur growth but also influence the duration of inactivity following each period of hair growth. Administration of deoxycorticosterone as a mineralocorticoid supplement had no effect on initiation of fur growth. It would appear that adrenal hormones are part of the mechanism through which photoperiod regulates fur growth in the mink. The identity of the adrenal hormones and their site of action is unknown. © 1992 Wiley‐Liss, Inc.
Cytoskeletal sheets appear as universal components of mammalian eggs
Authors: Gallicano G. Ian , McGaughey Robert W. , Capco David G.
Published: June 2005

The eggs of two mammalian species have been shown to contain novel cytoskeletal elements, referred to as cytoskeletal sheets, which undergo stage‐specific changes in spatial organization at three key developmental transitions, fertilization, compaction, and blastocyst formation. If cytoskeletal sheets have an integral role in these developmental transitions, the sheets should be present in the eggs of other mammals as well. We examined the eggs of four additional species to determine if sheets were present. Our results indicate that sheets were present and they can be categorized into two classes based on their surface appearance. Cytoskeletal sheets in eggs of hamsters and rats have a smooth surface appearance, while eggs from humans, cows, pigs, and mice have a fibrous surface appearance. In addition, we observed that species‐specific variations exist in the width of the sheets and in the density of the sheets (i.e., number per μm2) in the eggs. These species‐specific variations may relate to the role of the sheets during early development. © 1992 Wiley‐Liss, Inc.
Photo‐regulation of the hatching process of halibut (Hippoglossus hippoglossus) eggs
Authors: Helvik Jon V. , Walther Bernt T.
Published: June 2005

Hatching occurs in all vertebrates, yet knowledge about the control of this developmental transition is incomplete. Incubation of halibut Hippoglossus hippoglossus eggs in light results in sustained inhibition of hatching. The inhibitory efficacy of light is affected both by its intensity and its colour. Transfer of hatching‐arrested eggs to darkness (0.1 lux and below) reverses such inhibition and causes hatching of all eggs between 80–140 min later. Darkness is only required during the first 60 min of this induced hatching and initiates a signal which makes hatching irreversible and darkness independent. The darkness‐generated signal ultimately causes release of hatching enzyme, which digests the zona radiata so that the eggshell may be mechanically opened by the larva. We conclude that light serves as a natural cue for hatching in halibut eggs, and that halibut larvae in nature hatch in darkness. © 1992 Wiley‐Liss, Inc.
Xenopus laevis sperm proteins, previously identified as surface proteins with egg coat binding capability, are indeed histone H4, histone H3, and sperm specific protein SP2
Authors: Bernardini Giovanni , Donne Isabella Dalle , Norreri Sabrina , Negri Armando , Milzani Aldo
Published: June 2005

Recently, four Xenopus sperm proteins thought to be involved in binding to the egg envelope were identified (Lindsay and Hedrick, J. Exp. Zool., 245:286–293, '88). We have studied the three more abundant ones of apparent molecular weight of 14, 19, and 25 kd in SDS‐PAGE. We have shown that these proteins are indeed nuclear basic proteins: the 14 kd is the histone H4, the 19 kd is the histone H3, and the 25 kd is the sperm‐specific protein SP2. © 1992 Wiley‐Liss, Inc.
A quantitative autoradiographic study of 125I atrial natriuretic factor in the heart of a teleost fish (Conger conger)
Authors: Cerra M. C. , Canonaco M. , Tota B.
Published: June 2005

Quantitative receptor autoradiographic study of 125I‐atrial natriuretic peptide factor (ANF) in the heart of a teleost fish Conger conger has shown that a heterogenous distribution of 125I‐ANF binding exists in the different cardiac regions. Elevated ANF binding densities (3,790 fmol/mg protein) were encountered in the innermost layer (tunica intima) of the bulbus arteriosus while lower binding levels (293–403 fmol/mg protein) were revealed in atrium and ventricle. In order to determine 125I‐ANF binding characteristics (KD, Bmax) in the above cardiac sites, saturation binding assays were carried out. The results show that low 125I‐ANF KD values (28.8–52.6 pM) were found in the atrium and in the bulbus arteriosus with respect to the higher KD values (373 pM) of the ventricle. The number of binding sites were respectively 632 and 1,279 fmol/mg protein for the atrium and the ventricle, while a substantially elevated Bmax of 7,235 fmol/mg protein was found for the bulbus arteriosus. These results may furnish some insights concerning ANF receptor binding activity and its putative regulatory role of different cardiac functions. © 1992 Wiley‐Liss, Inc.
Identification of insulin‐like growth factor‐binding proteins in the circulation of four teleost fish species
Authors: Kelley Kevin M. , Siharath Kimmakone , Bern Howard A.
Published: June 2005

Insulin‐like growth factor‐binding proteins (IGF‐BPs) were demonstrated in the circulation of four teleost fish species. In the coho salmon (Oncorhynchus kisutch), serum binding of 125I‐labelled human IGF‐I (125I‐hIGF‐I) was competitively inhibited by addition of excess recombinant bovine IGF‐I (rbIGF‐I) in a manner similar to that when rat serum was used. Western‐ligand blot procedure using the same labelled hormone identified at least three major forms of IGF‐BPs in the plasma of all four teleost species investigated: coho salmon, striped bass (Morone saxatilis), tilapia (Oreochromis mossambicus), and longjawed mudsucker (Gillichthys mirabilis). The first form is around 40–50 kDa, may be regulated by growth hormone (GH), and seems to be a good candidate for the fish version of mammalian IGF‐BP3 (which is in the same size range and is GH‐regulated). The second and third forms are 29 kDa and 31 kDa and are good candidates for the fish versions of mammalian IGF‐BP1 and IGF‐BP2, respectively, as they appear to be regulated by insulin and are in the same size range as their mammalian counterparts. Functionally different classes of circulating IGF‐BPs may be conserved between fish and mammal. © 1992 Wiley‐Liss, Inc.
Comparison of Cl−‐absorption in the intestine of the seawater‐ and freshwater‐adapted eel, Anguilla anguilla: Evidence for the presence of an Na‐K‐Cl cotransport system on the luminal membrane of the enterocyte
Authors: Trischitta F. , Denaro M. G. , Faggio C. , Schettino T.
Published: June 2005

The mechanism(s) of absorption of chloride ions (Cl‐absorption), as measured by the short‐circuit current (Isc, μA·cm−2), was investigated in the intestinal middle part of the seawater‐(SW) and the freshwater‐(FW) adapted eel. Tissues, mounted in an Ussing chamber and continuously perfused by gravity flow on both sides with 20 mM HCO3− ‐ 1% CO2 Ringer's solution at pH 8.0, developed a serosa‐negative transepithelial voltage (Vt, mV) and an Isc that were both lower in FW‐adapted than in SW‐adapted eels.

Bilateral removal of Na+ or Cl− from the bathing solutions reduced both electrical variables to zero. Removal of K+ from or addition of Ba2+ (1 mM) to the luminal bath markedly decreased Isc and Vt. When a K+‐free plus Ba2+‐containing solution perfused the lumen, Isc and Vt were almost completely abolished. Luminal bumetanide (10−5 M), an inhibitor of Na+‐K+‐2Cl− cotransport, reduced Isc and Vt by about 90% in a few minutes.

Amiloride (10−3 M) and DIDS (4,4′‐diisothiocyanostilbene‐2,2‐disulphonic acid; 10−4 M), inhibitors of Na+/H+ and Cl−/HCO3− exchangers, and hydrochlorothiazide (10−4 M), an inhibitor of the Na‐Cl symport, had no effect on Isc and Vt when added luminally. Serosal ouabain (10−3 M) abolished Isc and Vt in about 30 min. All the above experimental manoeuvres led to similar results in both SW‐adapted and FW‐adapted eels.

The data suggest that in the intestine of both SW and FW eels, Cl−‐absorption is mediated by a luminally located neutral Na+‐K+‐2Cl− cotransport system. The basolaterally located Na+, K+‐ATPase, by generating an inwardly directed electrochemical gradient for Na+, provides the driving force for the active accumulation of Cl− by the electroneutral cotransporter. The K+ accumulated is refluxed by a Ba2+‐inhibitable luminal K+ conductance. © 1992 Wiley‐Liss, Inc.
Comparative kinetics of meiosis in hybrid crosses of Pacific oyster Crassostrea gigas and Suminoe oyster C. rivularis with the American oyster C. virginica
Authors: Scarpa John , Allen Standish K.
Published: June 2005

Interspecific hybridization of bivalve molluscs within the genera Crassostrea and Pinctada have yielded progeny of one parental type, leading to speculation of gynogenetic or androgenetic development. Therefore, meiotic and early mitotic events of oocytes from the oysters Crassostrea gigas and C. rivularis fertilized with C. virginica sperm, as well as the reciprocal and control crosses, were critically observed in samples taken up to 90 minutes post‐insemination. Chromosomal material in oocytes was visualized with the DNA‐specific fluorochrome DAPI and epifluorescence microscopy. All crosses produced fertilized oocytes which were observed to proceed through meiosis and early mitosis. Fertilization was ∼20% less successful in hybrid than straight crosses of C. gigas and C. virginica (P = 0.022) but no difference in fertilization was evident in C. rivularis and C. virginica crosses (P = 0.169). The time interval between meiotic and mitotic landmarks was not significantly different among all crosses within each full reciprocal cross. There was no cytological evidence of parthenogenetic, gynogenetic, or androgenetic development. In previous reports, non‐hybrid progeny found in hybrid groups were probably contaminants. © 1992 Wiley‐Liss, Inc.
Sexually differentiated mechanisms of sterility in interspecific hybrids between Oryzias latipes and O. curvinotus
Authors: Hamaguchi Satoshi , Sakaizumi Mitsuru
Published: June 2005

Fertility of interspecific hybrids between Oryzias latipes and O. curvinotus was examined. F1 females were able to lay eggs but males were sterile. Histological examination of the ovaries of hybrids revealed that oogenesis does not proceed normally in spite of the apparent fertility. Most oocytes degenerated at the pachytene stage of the meiotic prophase, and only a few entered the diplotene stage to develop into ova. Hybrid males could induce females to spawn eggs, an indication that they had differentiated completely into true males. However, they did not produce fertile sperm. Most germ cells in testes of hybrids passed through almost the entire process of spermatogenesis, but deviations from the normal course of events were observed during spermiogenesis. The condensation of chromatin in spermatids occurred, but the diameters of sperm heads were about 1.5‐fold larger than those of normal ones. Prominent abnormalities were apparent in the quantity and arrangement of microtubules in the cytoplasm. Abnormal spermatozoa were phagocytized by Sertoli cells. These observations indicate that the mechanisms of impaired gametogenesis in these interspecific hybrids are sexually differentiated. © 1992 Wiley‐Liss, Inc.