bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of feeding and photocycle on diel changes in plasma thyroid hormone levels in rainbow trout, Salmo gairdneri
Authors: Cook R. F. , Eales J. G.
Published: June 2005

In rainbow trout held in the laboratory within a narrow temperature range on a 12L:12D photocycle and fed once during the photophase there was a marked diel change in plasma L‐thyroxine (pT4) and a less pronounced change in plasma 3,5,3′‐triiodo‐L‐thyronine (pT3). Both photocycle and feeding regimes were experimentally altered to determine their influence. During starvation there was no significant diel change in plasma T4 in fish held in continuous darkness or under a phase‐shifted (12D:12L) photocycle and minor fluctuations under a normal (12L:12D) photocycle, although phase‐shifting did generally depress pT4. Feeding caused a tonic elevation in pT4, a marked postprandial surge in pT4 and facilitated a T4 surge due to light in the early photophase. Under most of these conditions changes in pT3 were less pronounced and peak pT3 levels usually followed the pT4 peaks, suggesting peripheral T3 derivation from T4. In conclusion, trout held at constant temperature show a diel profile in pT4 determined by an interaction between the feeding and photocycle regimes and which in turn probably influences delayed and more modest diel changes in pT3.
Recovery from environmental anaerobiosis and muscular work in the cockle, Cardium tuberculatum: Oxygen debt and metabolic responses
Authors: Meinardus‐Hager Georg , Gäde Gerd
Published: June 2005

The consumption of oxygen by Cardium tuberculatum, as well as the changes in levels of metabolites in tissue, were determined during recovery from 16 h of anoxic incubation and after exercise. Consumption of oxygen increased up to 3.5‐fold within 5 min of the termination of anoxic incubation or exercise. Control rates of oxygen consumption were restored within 10 h or 90 min, respectively (after environmental or functional anaerobiosis). With the transition to aerobic conditions or at the end of exercise, metabolites that had accumulated or been utilized during anoxia returned to levels near those of controls. No recovery phase, with an accumulation of the end products of anaerobic metabolism, was observed in Cardium tuberculatum. The time‐course for the consumption of oxygen during recovery was clearly related to metabolic events. During recovery from anoxic incubation, there was, initially, a short period of greatly enhanced consumption of oxygen, while the pools of phosphagens were replenished. During the subsequent 10 h of recovery, the rate of consumption of oxygen was slightly elevated and oxidation of the metabolic end products, D‐lactate and L‐alanine, took place. Recovery from exercise resulted in the rapid (30 min) and simultaneous replenishment of the pools of phosphagens and oxidation of octopine, while the oxygen consumption was greatly enhanced. A relationship was observed between the extent of the oxygen debt and the preceding stress (anoxia or exercise), and the duration of anaerobiosis.
Cardiovascular consequences of hypercalcemia during activity in two species of amphibian
Authors: Hillman Stanley S. , Withers Philip C. , Palioca Wayne B. , Ruben John A.
Published: June 2005

Exercise induced both a significant acidosis and hypercalcemia, measured as either total or ionic calcium in two species of amphibian, Bufo marinus and Rana catesbeiana. Hypercarbia induced a significant acidosis in both species but a significant hypercalcemia only in Bufo. Induction of hypercalcemia by infusion of Ca to concentrations equal to or greater than induced by exercise and hypercarbia had no significant effects in either species on mean arterial pressure, maximal rate of rise of systemic arterial pressure, blood flow rate, heart rate, pulse volume, or peripheral resistance during exercise. The ratio of ionic to total calcium was not significantly altered within a species by an experimental protocol. These data indicate that there are no discernible cardiovascular consequences during exercise of hypercalcemia induced by exercise or hypercarbia.
Innervation is necessary for the development of fast contraction kinetics of singing muscles in a katydid
Authors: Novicki Andrea , Josephson Robert K.
Published: June 2005

The twitch duration of mesothoracic wing muscles of the male katydid Neoconocephalus robustus (Insecta; Orthoptera; Tettigoniidae) decreases rapidly within the first 5 days of adulthood, to about half of its value in newly molted adults. To determine if this change is dependent upon neural input, male mesothoracic first tergocoxal muscles were unilaterally denervated on the second day of adulthood. The contraction kinetics of the denervated and contralateral innervated muscles were tested four days later. The development of rapid contraction kinetics was slowed or stopped in the denervated muscles, while the contralateral innervated muscles did become faster. Mesothoracic wing muscles of females do not develop faster contraction kinetics. When the female mesothoracic first tergocoxal muscle is denervated, there is no difference in twitch duration after 4 days between the innervated and contralateral denervated muscles. Therefore, denervation in newly molted adult male katydids interrupts a developmental program for the acquisition of adult contraction kinetics.
An autoradiographic analysis of N‐linked glycoconjugates in embryonic salivary gland morphogenesis
Authors: Bassett Kenneth E. , Spooner Brian S.
Published: June 2005

The synthesis, deposition, and loss of mannose‐bearing glyco‐conjugates during branching morphogenesis of embryonic mouse salivary glands has been evaluated. Day 13 embryonic mouse salivary glands were cultured for 44 hr, pulse labeled 4 hr with [3H]mannose, then fixed after 0, 2, 4, 8, or 24 hr, of chase in nonradioactive medium, and processed for autoradiography. Light microscopic autoradiograms of sectioned rudiments reveal extensive label within the epithelium, little label over the mesenchyme, and a concentration of radioactivity at the basal surface of the epithelium. Autora‐diograms of “chased” rudiments reveal a) no detectable loss of label from the epithelium or the basal epithelial surface over the first 8 hr, and b) significant label loss by 24 hr of chase at the basal epithelial surface, while moderate amounts of radioactivity remain throughout the rest of the epithelium. The [3H]bound material is insensitive to chondroitinase ABC, a glycosaminoglycan degradative enzyme, but is sensitive to tunicamycin presence in the culture medium.

Earlier studies showed that embryonic mouse salivary glands cultured in medium containing tunicamycin (25 ng/ml) continued normal epithelial branching while epithelial growth was inhibited. The present autoradiographic studies of [3H]mannose‐labeled rudiments demonstrate that tunicamycin causes a significant decrease in radioactivity, relative to controls. Thus, our results suggest that epithelial branching activity is independent of control levels of mannose‐containing/tunicamycin‐sensitive, glycoconjugate deposition.
Isolation and partial characterization of a “spawning female‐specific substance” in the teleost, Oryzias latipes
Authors: Hamazaki Tatsuo S. , Iuchi Ichiro , Yamagami Kenjiro
Published: June 2005

A “spawning female‐specific substance” (SF substance) [Hamazaki et al. (1985) J. Exp. Zool., 235:269–279] was isolated from the ascites fluid of the estrogen‐fed (EF) male or nonspawning female fish, Oryzias latipes, by gel filtration chromatography, followed by high‐performance ion‐exchange liquid chromatography (HPLC). Biochemical analyses revealed that the SF substance was a glycoprotein that contained 3.01% carbohydrates and showed 49,000 molecular weight (mw) on SDS‐PAGE. Amino acid composition and the carbohydrate content of the SF substance were similar to those of the glycoproteins, F1 and F2, which were purified from the hatching enzyme digest of the inner layer (zona interna) of egg chorion (egg envelope).

The inner layer of chorion from ovarian egg (oocyte) was separable into three different glycoproteins, ZI‐1 (mw 76,000), Z1‐2 (mw 74,000), and ZI‐3 (mw 49,000) on SDS‐PAGE. The major glycoprotein, ZI‐3, was found to show the mw and amino acid composition that were almost identical to those of the purified SF substance. These results indicate that a substance that is almost the same as the major component glycoprotein of the inner layer of chorion, in terms of the biochemical as well as immunological properties, is present out‐side the ovary and is produced in the liver of the spawning female fish as well as the EF fish.
Protamine polymorphism in Xenopus laevis laevis
Authors: Risley Michael S. , Eckhardt Ronald A.
Published: June 2005

Protamines from individual frogs of the subspecies Xenopus laevis laevis were compared by electrophoresis on polyacrylamide gels containing acetic acid, urea, and Triton X‐100 to determine if the expression of protamine genes differs among individuals. Two electrophoretic bands, SP2a and SP2b, appeared to be expressed as allelic variants. Of 33 frogs, 19 expressed only SP2a, 11 expressed both SP2a and SP2b, and three expressed only SP2b. Electrophoretic analysis of partial V8 protease digests could not distinguish the peptides released from SP2a and SP2b. Differences in sperm development between individuals were not detected by light or electron microscopy. The results suggest that protamine polymorphism can exist among individuals of a species without an apparent effect on sperm development or sperm function.
Plasma growth hormone levels in normal and stunted yearling coho salmon, Oncorhynchus kisutch
Authors: Bolton Jonathan P. , Young Graham , Nishioka Richard S. , Hirano Tetsuya , Bern Howard A.
Published: June 2005

A homologous radioimmunoassay was employed to assess plasma and pituitary growth hormone (GH) levels in coho salmon (Oncorhynchus kisutch) smolts and stunts. Although stunts have significantly reduced body weights and lengths, their plasma GH levels were 5‐fold higher than those of either freshwater or seawater smolts. Pituitary GH content was also greater in the stunts than in either group of smolts. The presence of elevated GH levels in a group of animals with reduced growth rates suggests deficiencies in recptor and/or mediating systems as the cause of stunting.
Osmolyte processing in the gut and an important role of the rectum in the land slug, Ariolimax columbianus (pulmonata; arionidae)
Authors: Deyrup‐Olsen I. , Martin A. W.
Published: June 2005

Experiments were carried out to investigate the role of the gut in the osmotic balance of the land slug Ariolimax columbianus. Previous investigators have shown that absorption of nutrients, calcium, and some heavy metals occurs in the slug's digestive gland and intestine. The only function suggested for the rectum, beyond transfer of the fecal mass, has been its possible involvement in lipid absorption. We collected hemolymph and fluids contained in different regions of the gastrointestinal tract and compared these with respect to osmotic pressure as well as to concentrations of ions (sodium, potassium, calcium, and chloride), glucose, and amino acids. The osmotic pressure of rectal contents was found to average one‐quarter the values of other fluids. In in vitro experiments sacs of intestine and rectum exposed to 1:4 mucosa:serosa osmotic gradients for 1 h showed transfer of fluid across the sac wall into the surrounding fluid. This transfer was significantly enhanced in the case of the rectum but not of the intestine, after dehydration or loss of hemolymph, and during immersion of the sacs in media containing the gastropod neurotransmitters FMRFamide, norepinephrine, and 5‐hydroxytryptamine, as well as arginine vasotocin. The data indicate that the rectum of the slug serves as a small but ready source of water available for use under conditions of acute water deficiency.
Involvement of thiol‐disulfide groups in the sensitivity of fully grown mouse oocytes to calcium‐free medium
Authors: De Felici Massimo , Dolci Susanna , Siracusa Gregorio
Published: June 2005

The lethality caused by calcium‐free medium (CFM) to fully grown mouse oocytes significantly decreases if a disulfide reducing agent (dithiothreitol, reduced glutathione, or L‐cysteine) is added to the medium. In this condition, most of the surviving oocytes do not spontaneously resume meiosis. We also show that the sulfhydryl content of fully grown oocytes, estimated by monobromobimane labeling, rapidly decreases during culture in CFM. The hypothesis is discussed that lethality of oocytes cultured in CFM may be a consequence of an alteration of thiol‐disulfide balance.
The Chaetopterus vitelline envelope is not necessary for the gamete interactions that lead to fertilization
Authors: Polk Patricia M. , Anderson Winston A. , Eckberg William R.
Published: June 2005

It has been recently shown that, in several genera of annelids, including Chaetopterus, fertilizing sperm attach to and fuse with egg microvilli which penetrate the vitelline envelope. This suggests that the annelid vitelline envelope may have no direct or obligatory role in normal fertilization. The present study was undertaken to investigate the involvement of the vitelline envelope in fertilization in Chaetopterus experimentally, by examining the fertilization of vitelline envelope‐free eggs quantitatively and qualitatively. Brief exposure of the eggs to isotonic sucrose‐EDTA removed the vitelline envelope as determined by both phase‐contrast and electron microscopy, rendered the eggs more sensitive to polyspermy and substantially reduced the binding of supernumerary sperm to eggs but did not decrease fertilizability as determined by sperm dilution assay and did not make the eggs more sensitive to cross‐fertilization. The events of fertilization were examined by electron microscopy and found to be very similar in vitelline envelope‐free eggs to those in intact eggs. We conclude that the vitelline envelope in Chaetopterus has binding sites for sperm but that it has no obligatory role in fertilization and is primarily involved in the prevention of polyspermy.
The regulation of amino acid metabolism during hyperosmotic stress in Acanthamoeba castellanii
Authors: Poulin Richard , Larochelle Jacques , Hellebust Johan A.
Published: June 2005

The effects of hyperosmotic stress on amino acid metabolism have been examined in Acanthamoeba castellanii incubated in a defined growth medium. Following hyperosmotic shock, the rapid appearance in the medium of previously ingested proline indicated a rapid release of pinosome contents induced by osmotic dehydration. Initially endocytotic uptake and protein synthesis were both markedly inhibited, but they recovered over the following hours. Total cell proteins decreased by 20% within 30 minutes after hyperosmotic stress, and this decrease was concomitant with a rapid accumulation of free ninhydrin‐positive substances.

Following a hyperosmotic shock, free alanine, glutamate, and proline transiently accumulated, in this sequence. Aminooxyacetate prevented the accumulation of alanine while greatly stimulating that of glutamate, but its effect on proline accumulation was small. In cells incubated with radioactive alanine, the accumulation of free alanine proceeded mostly from unlabeled precursors and coincided with a high rate of radioactive glutamate synthesis. This newly synthesized glutamate was extensively converted into proline, while proline synthesis from ornithine was barely stimulated. During acclimation to hyperosmotic conditions, osmoregulatory mechanisms in A. castellanii appear to rely only transiently on free amino acids, particularly on those whose access to main metabolic pathways is not allosterically regulated.
Experimental results on cell volume, growth rate, and macronuclear DNA variation in a ciliated protozoan
Authors: Santangelo Giovanni , Barone Enrico
Published: June 2005

Some species of ciliated protozoans vary their body volume when fed on preys of different sizes. This peculiarity has offered us the opportunity to examine the relationship between changes in cell volume, amount of macronuclear DNA (maDNA), and cell division rates in subclones derived from a single clone of the ciliate Blepharisma japonicum (Order Heterotrichida). Our results demonstrate that food‐induced size changes in this single‐celled organism are accompanied by substantial changes in maDNA content and in reproduction (cell division) rate. We find a strong, direct linear correlation between cell volume and maDNA quantity, and an inverse linear correlation between cell volume and reproduction rate. No correlation between cell reproduction rate and maDNA amount was found. We conclude that food‐induced coordinate change in cell volume, maDNA content, and cell division rate in this organism may be an effective mechanism for rapid phenotypic change in response to variable environmental conditions.
Flow cytometric analysis of ploidy in the axolotl, Ambystoma mexicanum
Authors: Tank Patrick W. , Charlton Ronald K. , Burns E. Robert
Published: June 2005

Although recent experiments on pattern formation during amphibian limb regeneration have relied on the use of triploid marked cells, the purity of the triploid donor has not been proven. To test the purity of the donor, blood (which contains noncycling nucleated red blood cells) was collected from the gills of 12 pressure‐induced triploid axolotls from two unrelated spawnings. Blood was also collected from 12 untreated sibling animals to serve as diploid controls. The blood samples were placed into a propidium iodide stain solution that had been adjusted to amphibian tonicity by the addition of distilled water. Samples were analyzed on an EPICS V (Coulter) flow cytometer. A minimum of 20,000 cells were analyzed in each sample at a flow rate that did not exceed 1,000 cells/second. In the diploid group, 88.6% of the cells were collected in channels of the DNA histogram corresponding to a 2C G1/G0 DNA content (channel 71±10) and 0.9% were collected in channels corresponding to a 3C G1/G0 DNA content (channel 106±10). In the triploid group, 99.2% of the cells were collected in nondiploid channels and only 0.8% were collected in channel 71±10. Utilizing the average peak channel number for the diploid group of 12 animals an average haploid channel number of 35 was calculated. The triploid group of animals exhibited DNA ploidy that averaged one haploid channel number above that of the diploid group. Based on forward angle light scatter, nuclei obtained from triploid red blood cells were observed to be larger than nuclei from diploid blood. Preliminary data are presented which demonstrate that the ploidy characteristics of solid tissues (brain, cornea, spleen, muscle, and limb blastemal mesenchyme) agree with those presented for blood.
Role of peanut‐lectin‐affinity molecules (PLAM) on primordial germ cells in the initial determination of sex in anura
Authors: Shirane Terukiyo
Published: June 2005

Peanut lectin (PNA) or N‐acetylgalactosamine (galNA, a part of the disaccharide unit which is recognized by PNA) was injected into the coelomic cavity of anuran larvae at the developmental stages during which the genital ridges were growing, and the effect of these compounds on the initial determination of gonadal sex was examined. The treatment with PNA tended to inhibit (or perturb) the expression of feminizing gene(s) in Rana japonica, and of both feminizing and masculinizing genes in R. nigromaculata. In contrast, treatment with galNA suppressed the expression of masculinizing gene(s) considerably. In terms of the initial determination of gonadal sex during normal development, these results suggest that the PNA‐affinity molecule (PLAM) of primordial germ cells acts as a trigger for the expression of genes that control sexual differentiation of somatic cells. Furthermore, the somatic cells (perhaps mesenchymal and/or epithelial cells), which respond to the stimulus via the PLAM of primordial germ cells, may differ in terms of the threshold for such a response between genetic males and females. This result suggests the mesenchymal and/or epithelial cells are not sexually predetermined, but rather that sexual determination follows the response to some signal(s) mediated by the PLAM.
Metabolic test of volatile odor labels as kin recognition cues in honey bees
Authors: Moritz Robin F. A. , Southwick Edward E.
Published: June 2005

The ability of worker honey bees to discriminate between kin and non‐kin was revealed using a metabolic bioassay. Groups of workers (test group) exposed to odors of unrelated bees (odor group) showed short‐term increases in metabolic activity. The magnitude of the metabolic reaction was closely correlated with the genetic relationship between odor and test groups. Worker test groups reacted to both worker and drone odor groups whereas drone test groups did not respond in this bioassay. The results support the theory of inclusive fitness.
Blood‐gas, acid‐base, and electrolyte responses to exercise in larval Ambystoma tigrinum
Authors: Rohrbach Jay W. , Stiffler Daniel F.
Published: June 2005

Larval Ambystoma tigrinum were non‐occlusively cannulated in the truncus arteriosus and allowed to recover 20–24 h. Upon recovery, control blood samples were removed, and the animals were exercised to exhaustion by encouraging swimming with a sponge forceps. The exercise led to a 5–6 fold increase in plasma lactate concentration which persisted 4–8 h. This lactacidosis caused the blood pH to drop from about 7.72 to below 7.10 in 30 min. Recovery was complete after 8 h. The acidosis was mixed with a pronounced respiratory component as P more than doubled during the same period. Bicarbonate concentration decreased from 12 mM to about 6 mM following exercise and recovered over the following 8 h. Similarly, strong ion difference was depressed following exercise but recovered during the ensuing 8 h. When exercised animals were forced to recover in running distilled water to deprive cutaneous ion transport mechanisms of access to ions, the results were quite different. The recoveries of pH, [HCO3−], and strong ion difference lagged 1–4 h behind the recoveries of these parameters in the tap water group, suggesting the participation of cutaneous ion transport in the recovery process. Ionic flux measurements demonstrated an increase in Na+ influx during the recovery period as well as increases in both Na+ and Cl− effluxes. The increases in efflux were much larger than observed increments in influx, placing the animals in negative ion balance and obscuring the significance of the changes in influx to acid‐base balance. Measurement of circulating aldosterone revealed a large increase in the concentration of this steroid hormone during recovery.
Plasma levels of glucose, alanine, lactate, and β‐hydroxybutyrate after mammalian insulin treatment in the American bullfrog (Rana catesbeiana)
Authors: deRoos Roger , Rumpf Ronald P.
Published: June 2005

Serial blood samples were collected from the adult American bullfrog (Rana catesbeiana) via a non‐occlusive cannula chronically placed in the systemic subdivision (aortic) of the right truncus arteriosus. Plasma glucose, alanine, lactate, and β‐hydroxybutyrate levels were estimated by standard enzymatic procedures. The metabolites remained relatively stable in the control animals during the 8‐day experiments. A single infusion of mammalian insulin (5, 15, or 45 IU/kg body weight) via the cannula depressed plasma glucose and alanine to near or below detectable levels that required a minimum of 3 days to return to approximately the time‐zero levels. Plasma lactate also fell severely after the infusion, but subsequently displayed precipitous surges followed by sharp declines on days 1 and 3, and also in some animals on day 5. In contrast, plasma β‐hydroxybutyrate levels were not significantly altered by insulin. Despite the severe depressions of plasma glucose, alanine, and initially lactate, no symptoms were observed in the bullfrogs infused with 5 or 15 IU of insulin. The carnivorous adult bullfrog consumes abundant protein and lipid, but little carbohydrate, and is adapted to periods of food scarcity. The results are consistent with the hypothesis that the bullfrog may rely on non‐esterified fatty acids and ketone bodies as primary energy sources. Glucose, most of which must be synthesized, probably serves to maintain muscle glycogen reserves that are used for anaerobic glycolysis when the animal is engaged in predation, escape, or other vigorous activity. If other tissues and organs require glucose as a fuel, the amounts must be exceptionally small.
Relationship between nuclear DNA synthesis and centrosome reproduction in sea urchin eggs
Authors: Sluder Greenfield , Lewis Kirsten
Published: June 2005

The importance of nuclear DNA synthesis for the doubling, or reproduction, of centrosomes in cells that are not growth‐limited, such as sea urchin eggs, has not been clearly defined. Studies of enucleated, fertilized eggs show that nuclear activities are not required at each cell cycle for the normal reproduction of the complete centrosome. However, other studies report that the inhibition of nuclear DNA synthesis in intact eggs by the drug aphidicolin prevents centrosome reproduction and entry into mitosis as seen by nuclear envelope breakdown. To resolve this paradox, we systematically characterized the effect of aphidicolin on cell division in eggs from three species of sea urchins. Eggs were continuously treated with 5 or 10 μg/ml aphidicolin starting 5 min after fertilization. This blocked total incorporation of 3H‐thymidine into DNA by at least 90%, as previously reported. We found that the sperm aster always doubles prior to first mitosis. Over a period of several hours, the centrosomes reproduce in the normal 2‐4‐8‐16 fashion, with a period that is longer and more variable than normal. In every culture, a variable percentage of the eggs undergoes nuclear envelope breakdown. Once broken down, the nuclear envelope never visibly reforms even though centrosomes continue to double. Fluorescent labeling of DNA revealed that the chromatin does not condense into discrete chromosomes. Whether or not the nuclear envelope breaks down, the chromatin appears as an amorphous mass of fibers stretched between first two and then four asters. Later, the nuclear envelope/chromatin loses its association with some or all centrosomes. Our results were the same for all eggs at both drug concentrations. Thus, nuclear DNA synthesis is not required for centrosome reproduction in sea urchin eggs.
Photoperiodic control of antler cycles in deer: VII. Role of light vs. dark in suppression of circannual rhythms
Authors: Goss Richard J.
Published: June 2005

The antler replacement cycle in the sika deer (Cervus nippon) is abolished on simulated equatorial photoperiods (12L/12D), the old antlers failing to be regenerated for indefinite durations. Constant but unequal light and dark periods have been shown to permit expression of circannual rhythms, as have constant and equal periods not measuring 12 hr in length. To test whether equinoctial circannual suppression could be attributed to the 12‐hr durations of the light periods or the dark periods, groups of yearling deer were exposed to 12L/9D, 9L/12D, 12L/16D, or 16L/12D, beginning on the autumnal equinox. All such deer cast and regenerated their antlers by spring. Therefore, suppression of the circannual antler cycle on 12L/12D is due neither to the 12‐hr photoperiod, nor to the 12‐hr scotoperiod, but to a combination of both.
Budding, life‐span, regeneration, and colonial regulation in the ascidian, Symplegma reptans
Authors: Sugino Yasuo M. , Nakauchi Mitsuaki
Published: June 2005

In the colonial ascidian, Symplegma reptans, the oozooid from which a particular colony has developed always degenerates about 30 days after metamorphosis, while all other zooids of the same colony are vigorous. Furthermore, an irregular type of regeneration, “blastogenic regeneration” (regeneration with the aid of budding), occurs if the zooids or their fragments are isolated under artificial conditions. Employing this species, we examined how budding and the life‐span of a zooid are affected by the other zooids of the same colony and studied the relationship between the nature of fragments of zooids and the mode of regeneration. To survey the effects of the other buds and zooids of the same colony, all buds from the oozooid were removed. The zooids from which buds were removed made about twice as many buds as the controls, and they lived a little longer than the controls. This result suggests that budding of a zooid is inhibited by the ambient zooids in the same colony. When the fragments of zooids were cultured alone, they regenerated either by epimorphosis or by blastogenic regeneration according to the extent of surgical removal of tissue. In cases in which two or more buds were formed during blastogenic regeneration, only the first bud grew. These results indicate that budding and regeneration are regulated both at the zooidal level and at the colonial level.
Sources of calcium and the involvement of calmodulin during steroidogenesis and oocyte maturation in follicles of Rana pipiens
Authors: Francisco Susan Kleis‐San , Schuetz Allen W.
Published: June 2005

In the amphibian ovarian follicle, progesterone production is thought to induce maturation of the enclosed oocyte. Intracellular mechanisms regulating these events in the somatic and germ cells are incompletely understood. However, calcium appears to play a role in the production and action of progesterone. Experiments using calcium antagonists were carried out to delineate the role of extra‐ and intracellular calcium during in vitro stimulation of follicular steroidogenesis and oocyte maturation. Calcium‐free medium, verapamil, and La3+ were used to block Ca2+ influx and inhibited follicular progesterone accumulation in response to frog pituitary homogenate (FPH) or exogenous cAMP + IBMX. Progesterone accumulation was not impaired under identical conditions when pregnenolone was added to cultured follicles. TMB‐8, an inhibitor of intracellular Ca2+ mobilization, partially inhibited progesterone levels stimulated by FPH at low doses but not higher doses of the inhibitor. However, TMB‐8 inhibited FPH‐induced oocyte germinal vesicle breakdown (GVBD) in a dose‐dependent manner, as well as maturation due to exogenous progesterone or La3+. Calmodulin antagonists, W‐7, R24571, and trifluoperazine, were used to assess the involvement of calmodulin in the responses of these two cell types. All three antagonists inhibited progesterone accumulation induced by FPH with the apparent order of potency being R24571 > W‐7 > TFP. W‐7 inhibited cAMP‐induced progesterone elevation, but had no effect on conversion of pregnenolone to progesterone. Of these three calmodulin antagonists, only R24571 exhibited a dramatic ability to inhibit GVBD induced by exogenous progesterone and was associated with morphologic alterations in the oocytes. These data suggest that Ca2+, acting through calmodulin at some specific step(s) distal to cAMP elevation and prior to pregnenolone formation, is involved in FPH‐induced progesterone accumulation, apparently with the participation of both extracellular and intracellular pools of Ca2+. In the oocyte, mobilization of Ca2+ from intracellular stores appears to be of primary importance to maturation while extracellular Ca2+ is not. These data provide further evidence that Ca2+ mediates the hormonally provoked responses in both cell types in the intact follicle, but that the source of Ca2+ may differ. Using intact follicles it seems apparent that exploiting this difference with selective inhibitors provides a means for differential modulation and functional uncoupling of these cells with regard to steroidogenesis and steroid action.
In vitro study of serum protein synthesis in the livers of larvae and adults of the lamprey, Petromyzon marinus L.
Authors: Ito Misa A. , Filosa Michael F. , Youson John H.
Published: June 2005

Using electrophoretic and immunoelectrophoretic methods we had previously characterized three major serum proteins of the lamprey, Petromyzon marinus: SDS‐I, CB‐III, and AS. SDS‐I is present in highest concentration at the upstream migration period of the life cycle, whereas AS is present in highest concentration at the larval (ammocoete) period. Since the liver has been shown to be the major site of serum protein synthesis in many vertebrates, it may be assumed that the lamprey liver also engages in the same activity. In the present work we present evidence that the three major serum proteins of the lamprey are indeed synthesized by the liver. Liver slices from the larval and upstream migrant period were separately incubated with [35S]‐methionine. After 2 or 3 hours of incubation, Triton X‐100‐soluble material was extracted from the liver slices and examined by crossed immunoelectrophoresis (CIE) and autoradiography. When extracts from the larval liver were run with antiserum made against larval serum, autoradiograms of the CIE patterns showed that AS and CB‐III had been synthesized; the synthesis of AS was confirmed by the use of monospecific antiserum against AS. There was no indication of SDS‐I synthesis during the incubation period. When extracts from the upstream migrant liver were run with antiserum made against whole serum from upstream migrants, autoradiograms of the resulting CIE patterns showed that SDS‐I and CB‐III had been synthesized; when antiserum against AS was used for the CIE, autoradiograms showed that AS had not been synthesized during the incubation period. Thus the differences in concentration of AS and SDS‐I in the different periods of the life cycle may be due to differences in the synthetic capabilities of the liver at these periods.
Characterization of turtle liver nuclear estrogen receptors, seasonal changes, and pituitary dependence of cytosolic and nuclear forms
Authors: Riley Deborah , Callard Ian P.
Published: June 2005

A nuclear hepatic estrogen receptor was characterized in the female turtle Chrysemys picta for the first time. The characteristics of this receptor were similar to those previously described in the cytosol, using DNA‐cellulose column chromatography (Riley et al., '87). The development of a different method for measurement of turtle cytosolic estrogen receptors allowed comparison of cytosolic and nuclear estrogen receptor regulation. Cytosolic and nuclear estrogen receptors exhibited high affinity (Kd, nuclear, 2.3 × 10−9M), limited capacity (10 – 170 fmol/g liver), steroid specificity for natural and synthetic estrogen, and target tissue specificity. Sucrose gradient analyses of crude cytosol revealed specific peaks of radioactivity at 4S and 9S, however a single 4S peak was present in nuclear extracts and ammonium sulfate precipitated cytosol. The levels of liver nuclear estrogen receptor changed significantly during the annual reproductive cycle, while cytosolic receptors were maintained at a constant level. Vitellogenic animals had higher levels of nuclear estrogen receptor and a greater percentage of total receptor in the nuclear fraction. In nonreproductive animals with low nuclear and high cytosolic estrogen receptor, short term (20 h) or chronic (1 week) estrogen exposure resulted in an increase in nuclear receptor to levels similar to naturally vitellogenic animals; however, depletion of cytosolic receptor was observed. Hypophysectomy of reproductively inactive animals resulted in loss of nuclear estrogen receptors in both control and estrogen‐injected turtles and restoration was achieved by ovine growth hormone (oGH) replacement. Cytosolic estrogen receptor levels and depletion after estrogen treatment were unaffected by hypophysectomy, however an increase above control occurred in hypophysectomized turtles treated with oGH. These data suggest that both estrogen and a pituitary factor similar to oGH are necessary for the achievement of high levels of nuclear estrogen receptor associated with vitellogenesis.
Cardiovascular effects of prostaglandin I2 and prostaglandin F2α in the unanesthetized bullfrog, Rana catesbeiana
Authors: Robleto Daniel O. , Herman Ceil A.
Published: June 2005

The cardiovascular effects of prostaglandin (PG)I2 and PGF2α were compared in the unanesthetized American bullfrog (Rana catesbeiana). Control mean arterial pressure (MAP) and heart rate (HR) were 25.7 ± 1.1 mm Hg and 35.1 ± 1.1 beats/min, respectively. Intravenous injections of PGI2 decreased MAP and increased HR in a dose‐dependent fashion over the range of concentrations tested (0.03, 0.3, 3, and 10 μg/kg‐body weight [bw]. Neither atropine (1 mg/kg‐bw) nor verapamil (1 mg/kg‐bw) treatment altered the MAP or HR responses to PGI2 (3 μg/kg‐bw). However, propranolol (5 mg/kg‐bw) significantly blunted the hypotensive effects without affecting the increase in HR. Prostaglandin F2α (tested at 0.3, 3, 30, and 100 μg/kg‐bw) increased both MAP and HR. Mean arterial pressure increased with concentrations greater than 0.3 μg/kg‐bw and reached peak effects at 30 μg/kg‐bw. Prostaglandin F2α increased HR at doses greater than 0.3 μg/kg‐bw. Neither the pressor nor positive chronotropic effects of PGF2α (30 μgk/kg‐bw) were affected by atropine or propranolol. However, verapamil significantly attenuated the pressor effects without affecting the increase in HR. These results demonstrate that both prostaglandins have qualitatively similar effects on HR, but opposite effects on MAP. Prostaglandin I2 is a hypotensive prostaglandin, while PGF2α is hypertensive. The pressor effects of PGF2α are partially dependent on calcium influx. The positive chronotropic effects of both prostaglandins are indepdent of the autonomic nervous system, suggesting a different mechanism of action.
Conditions for the appearance of maturation promoting factor following germinal vesicle disruption of prophase‐arrested starfish oocytes
Authors: Guerrier P. , Neant I. , Charbonneau M. , Moreau M.
Published: June 2005

In this paper, we report that so‐called “incompetent” prophase‐arrested oocytes of Marthasterias glacialis and Asterias rubens fail to produce any aster or spindle when their nucleoplasm and cytoplasm are mixed via pressure or microinjection. We also show that the same incompetent oocytes always complete their maturation up to second polar body extrusion and female pronucleus formation following a 30 sec shaking treatment, which results at once in germinal vesicle (GV) disruption and produces the same mixing of their nuclear and cytoplasmic compartments.

32P phosphate incorporation into proteins and cell fusion experiments indicates that this mechanical treatment induces an increased protein phosphorylation and triggers the formation of active maturation promoting factor (MPF) molecules which are not produced following a simple nucleoplasm transfer. While bovine serum albumin (BSA) had no effect on this process, the intracellular Ca2+antagonists (2‐[(2‐bist[Carboxymethyl]‐amino‐5‐methylphenoxy)‐methyl]‐6‐methoxy‐8‐bis[carboxy‐methyl]‐aminoquinolinetetrakis‐[acetoxymethyl]ester) (Quin 2‐AM) and 8(N‐N‐diethylamino) octyl‐3,4,5‐trimethoxybenzoate (TMB 8) were found to inhibit both hormone‐induced and shaking‐induced maturations. These results exclude the possibility that shaking might act by releasing arachidonic acid in the external medium. Instead, they suggest that such a mechanical treatment may trigger the same significant changes in Ca2+ concentration or compartmentalization that have been shown to occur following hormone stimulation and that seem to be required for activating resting female centrioles as well as latent MPF precursors and protein kinases.
Formation of flagella during interphase in secondary spermatocytes from Xenopus laevis in vitro
Authors: Abé Shin‐Ichi , Asakura Shoji , Ukeshima Atsumi
Published: June 2005

In cell culture, single motile flagella, 1 μm in length, were observed to grow from secondary spermatocytes of Xenopus laevis within 2–3 hours after telophase I, at 22°C. About 90% of the secondary spermatocytes formed flagella as observed by phase‐contrast microscopy. The flagella grew up to 2–6 μm in length during interphase II, which lasted about 18 hours. The presence of the “9 + 2” microtubular structure of the flagellar axonemes of secondary spermatocytes was confirmed by electron microscopy. When chromosomal condensation began (prophase II), the flagella were resorbed into the cells and, after the second meiotic division, a flagellum was formed again by each of the round spermatids. Thus, there appears to be a close relationship between the meiotic division cycle and the formation of flagella. The possible contribution of Sertoli cells to the formation of flagella in secondary spermatocytes was examined by reducing the number of Sertoli cells to less than ten per culture. Under these conditions, flagella formed in secondary spermatocytes with very high efficiency. It is very likely that secondary spermatocytes form flagella in vivo, since the secondary spermatocytes were observed to have flagella immediately after dissociation of the testes.
Human sperm acrosome reaction‐initiating activity associated with the human cumulus oophorus and mural granulosa cells
Authors: Siiteri Jon E. , Dandekar Pramila , Meizel Stanley
Published: June 2005

This report describes the detection and partial characterization of preovulatory human cumulus oophorus and mural granulosa cell‐associated activity capable of initiating the human sperm acrosome reaction (AR) in vitro. Fragments of preovulatory human cumulus (cells plus extracellular matrix) were washed 3 times, incubated for 24 hr and the spent media and washes assayed for their ability to initiate the human sperm acrosome reaction (AR) in vitro. AR activity was present in the first two washes but not the third wash; however, AR activity was recovered in the spent medium after 3×‐washed fragments were incubated for 24 hr under conditions which maintained the viability of the cumulus cells. The spent media of preovulatory human mural granulosa cells contained AR‐initiating activity after 1–3, 3–6, and 6–9 days of culture. The properties of the AR activity present in spent media of human cumulus fragments included resistance to loss of activity during treatment with pronase; resistance to loss of activity during treatment with chondroitinase ABC or bacterial hyaluronidase; heat stability after overnight incubation; lack of extraction by chloroform‐methanol; an apparent molecular weight (MW) of 50,000, as determined by Sephadex G‐75 column chromatography; conversion to a lower apparent MW activity by incubation with pronase. These properties are also characteristic of a fraction derived by Sephadex G‐75 chromatography of preovulatory human follicular fluid which also has been shown to stimulate the human sperm acrosome reaction in vitro. The AR activity from spent media of human mural granulosa cells is also found in a 50,000 MW Sephadex G‐75 fraction. We propose that the sources of the 50,000 MW human follicular fluid AR activity are the cumulus oophorus and the mural granulosa cells.
Inhibition of RNA synthesis in embryo of Xenopus laevis by protease inhibitor
Authors: Miyata Shohei , Shimazaki Taketo , Okamoto Yoriyuki , Motegi Naoya , Kitagawa Mistuo , Kihara Hirozi K.
Published: June 2005

We have studied the role of proteases during the development of Xenopus laevis embryos with the aid of protease inhibitors. The activity of proteases was found to be only minimal in the unfertilized egg and during the initiation of development, but activity began to increase at the morula stage. When the activity of proteases was inhibited by antipain, an inhibitor of endopeptidase activity, RNA synthesis in the embryo was inhibited. To examine the relationship between the inhibitory effect of antipain on protease activity and its effect on RNA synthesis, antipain was reduced with NaBH4 to inactivate its protease inhibitory activity. The reduced antipain did not inhibit RNA synthesis in the embryo. Antipain effectively inhibited synthesis of both rRNA and poly(A)+RNA but not 4S RNA. We therefore suggest that protease activity plays an important role in the initiation and/or continuation of RNA synthesis.
First successful transfer of cryopreserved feline (Felis catus) embryos resulting in live offspring
Authors: Dresser B. L. , Gelwicks E. J. , Wachs K. B. , Keller G. L.
Published: June 2005

Sexually mature domestic cats were hormonally stimulated to induce superovulation; embryo recovery was accomplished by laparotomy. Embryos were frozen by conventional embryo freezing methods used in the domestic cattle embryo transfer industry. Thawing was achieved in a 28°C or 37°C waterbath or in ambient air. Overnight culture of the frozen‐thawed embryos in a supplemented Nutrient Mixture F‐10 (Ham's) or Earle's Balanced Salt Solution with 20% heat‐treated newborn calf serum resulted in five successful term litters from recipient queens. Embryo recipients who became pregnant had been treated with a subcutaneous injection of follicle‐stimulating hormone (FSH‐P) once every 24 hr for 6 days in the amount of 0.2 mg/day for the first 5 days and 0.1 mg on the sixth day, followed by two intramuscular 750 IU injections of human chorionic gonadotropin 24 hr apart, beginning on the same day as the sixth injection of FSH‐P.
Treatment of brachial nerves with colchicine inhibits limb regeneration in the newt Notophthalmus viridescens
Authors: Scadding Steven R.
Published: June 2005

In urodele amphibians, limb regeneration is dependent on innervation and is blocked by the administration of colchicine. The objective of this experiment was to determine if colchicine blocks limb regeneration by a direct action on the blastema cells or by an indirect action on the nerves, specifically, if colchicine treatment of the brachial nerves would inhibit limb regeneration in the newt Notophthalmus viridescens. Colchicine was applied to the nerves by implanting a colchicine‐loaded silastin block adjacent to the brachial nerves of an amputated newt limb. With appropriate dose levels of colchicine, limb regeneration was completely inhibited. Contralateral control limbs, carrying unloaded silastin blocks, and control limbs with colchicine‐loaded blocks implanted equidistant from the blastema, but not adjacent to the brachial nerves, regenerated normally. Thus, the results indicate that the colchicine inhibition of limb regeneration is mediated by colchicine effects on the nerves. The possible mechanism of colchicine action on nerves may involve either wallerian degeneration, or inhibition of axoplasmic transport, or both.
Aldehyde dehydrogenase activity in brain and liver of the rainbow trout (Salmo gairdneri Richardson)
Authors: Nilsson Göran E.
Published: June 2005

Aldehyde dehydrogenase (ALDH) activity was measured in brain and liver of rainbow trout by using 3,4‐dihydroxyphenylacetaldehyde (DOPAL, the biogenic aldehyde derived from dopamine) as the substrate. The amount of the corresponding acid produced was quantified by high‐performance liquid chromatography with electrochemical detection. Both in brain and liver, the ALDH activity showed a high affinity for the substrate with an apparent Km of 3.7 μM in brain and 2.4 μM in liver. The kinetic experiments with brain ALDH also indicated the presence of an isozyme with a low affinity for DOPAL with a Km around 150 μM. The Vmax of the liver ALDH activity varied between 179 and 536 nmol/min·g, i.e., about 25–75 times higher than that of the low‐Km activity in brain. The ALDH activity showed a maximum around pH 8.5, it was stimulated by Mg2+, and disulfiram was found to be a potent inhibitor of the enzyme. The results suggested that the majority of the ALDH activity was located in mitochondria (60–70% with regard to the brain and 70–80% with regard to the liver), while the remaining activity appeared to be cytosolic in both organs. No microsomal ALDH activity could be found.