bluuebunny/crossref_metadata_2025 huggingface dataset:
A possible mechanism of chemical induction of conjugation in Paramecium: Importance of cationic exchange on the cell surface
Authors: Kitamura Akio , Hiwatashi Koichi
Published: June 2005

The effect of calcium ions on the chemical induction of conjugation in Paramecium caudatum was examined in the simplest medium that induces conjugation, containing either KCI or MnCl2 in TRIS‐HCI buffer. The concentration of K ions necessary for induction increased with the concentration of Ca ions added. The maximum induction of conjugation took place at a constant ratio of the K+ concentration to the square root of the Ca2+ concentration regardless of their ionic strengths. Similar results were obtained in the induction by Mn2+, where the square root of the Mn2+ concentration is proportional to the square root of the Ca2+ concentration for maximum induction. The results strongly suggest that the activation for conjugation is closely related to removal of Caions bound to the cell surface and that an ion exchange system on the cell surface governed by Gibbs‐Donnan principle has an essential role in the chemical induction of conjugation in Paramecium.
Induced androgenesis in rainbow trout
Authors: Parsons James E. , Thorgaard Gary H.
Published: June 2005

Androgenesis was induced in rainbow trout, Salmo gairdneri, when eggs were irradiated with Co60 gamma‐radiation prior to fertilization. Peak survival of the androgenetic haploids occurred at a radiation dosage of 3 × 104 roentgen (R). The survival of these androgenetic haploid embryos was not significantly lower than that of the gynogenetic haploids. Haploidy and all‐paternal inheritance were confirmed by chromosome counts and by the use of a recessive albino color marker. If androgenetic diploids can be produced, androgenesis should prove useful in the production of inbred lines for genetic studies and breeding programs.
In vitro 11‐ketotestosterone and 17α,20β‐dihydroxy‐4‐pregnen‐3‐one production by testicular fragments and isolated sperm of rainbow trout, Salmo gairdneri
Authors: Ueda Hiroshi , Kambegawa Akira , Nagahama Yoshitaka
Published: June 2005

Two different testicular tissue preparations, testicular fragments and isolated sperm were incubated in the presence or absence of chumsalmon gonadotropin (SGA, lμg/ml), 17μ‐hydroxyprogesterone (17μ‐OHprog, 0.1 μg/ml) and testosterone (T, 0.1 μg/ml). 11‐Ketotestosterone (11‐keto T) and 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (17α,20β‐diOHprog) in the incubation medium were measured by specific radioimmunoassay. Incubation of testicular fragments with SGA, 17α‐OHprog or T resulted in a highly significant increase in 11‐keto T levels in the incubation medium. Sperm preparations did not produce 11‐keto T under any incubation condition. Both testicular fragments and sperm preparations produced large amounts of 17α,20β‐diOHprog when incubated with 17α‐OHprog. SGA slightly stimulated 17α,20β‐diOHprog by testicular fragments but not by sperm preparations. These results suggest that different testicular elements are the sites of synthesis of 11‐keto T and 17α20β‐diOHprog. Furthermore, it is suggested the involvement of sperm in the production of 17α,2Oβ‐diOHprog in the testis of spermiating rainbow trout.
Changes in mitochondrial distribution and diffusion distances in muscle of goldfish upon acclimation to warm and cold temperatures
Authors: Tyler Seth , Sidell Bruce D.
Published: June 2005

Transmission electron microscopy of myotomal muscle from goldfish (Carassius auratus L.) reveals significant differences in distribution and density of mitochondria in animals acclimated to cold temperature (5°C) as compared to those acclimated to warm temperature (25°C). Micrographs of red and white muscle from these animals have been analyzed quantitatively for the stereological parameters Vv (volume density), Sv (surface density), and S/V (specific surface); and diffusion distances between mitochondria have been calculated as the harmonic mean of spacings between clusters of mitochondria (τh). The most dramatic differences occur in Vv, Sv, and τh of red muscle, Vv and Sv being significantly greater in cold‐acclimated animals and τh being smaller. In white muscle, Vv is significantly greater for cold‐acclimated animals than warm‐acclimated animals, but other parameters are not significantly different. Using our values of Sv as estimates of the surface area through which exchange of metabolites occurs and our values of τh as estimates of the distance over which diffusion occurs, we calculate that the diffusivity constant in the one‐dimensional diffusion equation for metabolites may be reduced in cold‐acclimated animals to as low as 0.29 that of warm‐acclimated animals while still maintaining absolute rates of diffusive flux between cytoplasm and mitochondria. It appears reasonable to assume that cold‐induced rises in the concentration of enzymes in fish muscle reflect changes in organellar densities–changes which may serve primarily to ameliorate the effect of temperature on diffusive exchange between mitochondria and cytoplasm rather than solely to overcome catalytic limitation as is widely assumed.
Cellular location and partial characterization of the alanine aminotransferase in ribbed mussel gill tissue
Authors: Paynter Kennedy T. , Ellis Lehman L. , Bishop Stephen H.
Published: June 2005

Differential centrifugation of ribbed mussel gill tissue homogenates and extraction of the mitochondrial fraction demonstrated that most (72%) alanine aminotransferase (AlAT) activity was mitochondrial. Subsequent characterization of the cytosolic activity demonstrated properties identical to those demonstrated by the mitochondrial enzyme. Both enzyme fractions showed little variation in Vmax with pH, had low Km's for ketoacid substrates, and were inhibited by aminooxyacetate (AOA), L‐cycloserine, and β‐chloro‐L‐alanine. It appears that the AlAT in ribbed mussel gill tissue is strictly mitochondrial and that alanine production during hypoxia or hyperosmotic stress must be mitochondrial.
Size regulation and morphogenetic localization in the Dentalium polar lobe
Authors: Render Jo Ann , Guerrier Pierre
Published: June 2005

Lobe removal experiments show that the Dentalium embryo's first polar lobe is necessary for larval apical tuft and posttrochal region development. The smaller second polar lobe is necessary only for posttrochal region development. When vegetal halves of eggs are isolated before fertilization and then fertilized, they form size‐regulated first polar lobes. These polar lobes are proportional to the isolated halves in size and are necessary for posttrochal region but not apical tuft development. When vegetal halves are isolated after fertilization and then refertilized, they form polar lobes with an average volume that is less than that of normal first polar lobes but greater than that of size‐regulated polar lobes. Like normal first polar lobes, these lobes are necessary for both apical tuft and posttrochal region development. Localization of apical tuft and posttrochal region determinants occurs before fertilization and cannot be altered by the process. Polar lobe size specification occurs at first fertilization but can be somewhat modified by subsequent fertilization events. Size regulation does not affect the localization of apical tuft and posttrochal region determinants but does alter the developmental role of the first polar lobe.
Intracellular chloride activity and pH during polar lobe formation and cytokinesis in eggs and embryos of Ilyanassa obsoleta
Authors: Conrad Gary W.
Published: June 2005

The objectives of this study were to compare membrane potential, intracellular chloride activity, and intracellular pH in unfertilized and fertilized eggs of Ilyanassa obsoleta throughout polar lobe formation and cytokinesis. Membrane potential, ψm, was measured with single‐ and double‐barrel microelectrodes containing 3 M KCl. Chloride activity, (Cl)c, was measured with single‐barrel, chloride‐sensitive microelectrodes. Intracellular pH, pHc, was measured with double‐barrel microelectrodes, utilizing an antimony‐filled barrel to monitor pHc.

Unfertilized eggs having a ψm of −13.7 mV displayed an average (Cl)c of 29.9 mM, whereas at electrochemical equilibrium, (Cl)ce, it would be 155.7 mM. This suggests that Cl is pumped out of the cell in eggs that are not fertilized. Fertilized eggs had a ψm of −78.2 mV and a (Cl)c of 18.6 mM. At electrochemical equilibrium, (Cl)ce would be 12.1 mM, thus suggesting that Cl is pumped into the cell in fertilized eggs. Double‐barrel microelectrodes measured a ψm of −69.0 mV and a pHc of 7.3 in fertilized eggs. The ψm, (Cl)c, and pHc remained stable as fertilized eggs underwent the cellular shape changes involved in forming first, second, and third polar lobes and first cleavage.
An acrosome reaction in sperm from the white sturgeon, Acipenser transmontanus
Authors: Cherr Gary N. , Clark Wallis H.
Published: June 2005

The A. transmontanus sperm possesses an elongate main body, a conspicuous acrosome, a midpiece, and a flagellum. Three membrane‐lined nuclear channels that are helically arranged extend from the acrosomal region to the midpiece. Sperm heads contain material that comigrates on sodium dodecyl sulfate (SDS)‐gels with actin. An acrosome reaction can be induced in freshwater with ionophore A23187, high pH, high Ca++, or egg water. This acrosomal reaction is a Ca+‐Mg+‐dependent event. The resulting acrosomal process (10 μm) originates from the subacrosome region and the nuclear channels. Non‐filamentous actin apparently polymerizes and forms the process.
Studies on the localization and activities of Concanavalin‐A‐reactive glycoproteins on the cell surface of sea urchin embryos
Authors: Matsumoto Emiko , Tonegawa Yasuto , Ishihara Katsutoshi
Published: June 2005

Inhibitory effects of Concanavalin A (con A) on sea urchin development were analyzed. Con A inhibited gastrulation at lower concentrations and disturbed cell association at higher concentrations. This cell‐dissociating effect was due to the binding of con A to specific sugar residues on the cell surface. By autoradiographic study on sectioned embryos, con A binding sites were shown to be mostly localized on cell membranes. The grain number increased during development, especially at the time of hatching, when functional cell association is known to be established. By dissociating embryos with Ca‐,Mg‐deficient artificial seawater (CMF‐SW), con A was shown to react with cell aggregation factor and with surfaces of dissociated cells. These results suggest that con‐A‐reactive materials on the cell surface are directly involved in the cell adhesion mechanism of sea urchin embryos.
Retinoic‐acid‐induced pattern completion in regenerating double anterior limbs of urodeles
Authors: Stocum David L. , Thoms Stephen D.
Published: June 2005

The effects of retinoic acid on the regeneration of double anterior lower arms in the adult newt, Notophthalmus viridescens, were investigated. Normally, double anterior lower arms regenerate a hypomorphic, symmetrical pattern of structures, which are distally complete; and double anterior upper arms regenerate a hypomorphic, symmetrical but distally incomplete pattern of structures. In limbs with a normal anteroposterior axis, the major effect of retinoic acid is to alter the proximodistal (PD) positional value of cells local at the amputation level to a much more proximal value, thereby creating duplications in the regenerate of structures proximal to the amputation plane (Thoms and Stocum, '84). Therefore, we predicted that double anterior lower arms treated with retinoic acid would regenerate like double anterior upper arms. However, in a substantial number of cases, each half of these double anterior lower arms regenerated a limb that was complete in the anteroposterior (AP) axis, with asymmetry corresponding to the half of origin. In addition, these regenerates were serially duplicated in the PD axis. These results indicate that retinoic acid can posteriorize the positional value of midline cells, leading to restoration of normal AP pattern, when the set of posterior‐half positional values is removed from the cross section of the limb.
The effects of Janus Green B on the temporal and spatial pattern of feather germ morphogenesis
Authors: Mayerson Paula L. , Fallon John F.
Published: June 2005

The normal timing and appearance of feather germs was per‐turbed by injecting the dye Janus Green B into the amniotic fluid of chick embryos at late stage 28, prior to the first appearance of feather germs. This treatment prevented feather germ morphogenesis in some regions while else‐where it delayed normal morphological development. The Janus Green B effect lasted for approximately 98 hours. Feather regions, which normally form epidermal placodes during the period of treatment, showed the longest delays in subsequent feather germ formation and were the most likely to remain featherless. These results suggest that the epidermal placode stage is critical for feather germ formation. Janus Green B appears to prevent feather germ morphogenesis by interfering with development prior to this critical stage. Since severely affected regions fail to recover their capacity to form feather germs, even after the period of sensitivity to the dye, a limited period of competence is suggested for feather germ formation.
The role of cell proliferation and cellular shape change in branching morphogenesis of the embryonic mouse lung: Analysis using aphidicolin and cytochalasins
Authors: Goldin Geoffrey V. , Hindman Heather M. , Wessells Norman K.
Published: June 2005

The formation of induced supernumerary buds in the embryonic mouse tracheal epithelium has been used as a model system to analyse the respective roles of cell proliferation and microfilament‐mediated cell shape change during branching morphogenesis. In order to analyse the mitotic events associated with the formation of epithelial buds, the induction of supernumerary tracheal buds by mesenchymal grafts was carried out with the inhibitor of DNA synthesis, aphidicolin, present in the culture medium for varying intervals of time during the 16‐hour inductive process. The presence of aphidicolin for 10 to 16 hours of the inductive period blocks the formation of induced tracheal buds, whereas the presence of the inhibitor for half of that time (either the first 8 hours or the last 8 hours) does not prevent this morphogenetic event from taking place, although smaller buds resulted from induction under these conditions. Both the inhibition of DNA synthesis and the recovery from 10 μM aphidicolin treatment, as measured by 3H‐thymidine incorporation, were found to occur rapidly. The addition of 2 μM dihydrocytochalasin B (or cytochalasin B) together with aphidicolin during the second half of the inductive period inhibits the formation of supernumerary buds and upon removal of the cytochalasin rapid formation of buds takes place. We conclude that the formation of epithelial buds during branching morphogenesis occurs as a result of enhanced localized cell proliferation coupled with epithelial cell shape change (or preservation of cell morphology) mediated by microfilaments, which have been observed in both the apical and basal cytoplasm of the epithelial cells in the region where branching of the trachea is taking place.
Structure‐Activity relations of LHRH in birds
Authors: Millar R. P. , King J. A.
Published: June 2005

Structural requirements in LHRH for gonadotropin‐releasing activity were investigated by comparing the activity of the natural vertebrate LHRH structural variants and synthetic analogues. Substitution of Arg8 results in a loss of activity of LHRH in mammals, whilst a number of amino acid substitutions for Arg8 retain high gonadotropin‐releasing activity in the chicken. Thus Arg8 of LHRH comprises an integral part of the binding site of LHRH and/or contributes towards the conformation of the binding site for the mammalian receptor while this does not pertain in the bird. The possibility that relative conformational stabilization of LHRH is important for biological activity in mammals but not birds, was supported by the demonstration that a γ‐lactam conformationally constrained analogue of LHRH was more active than LHRH in the mammalian system but equipotent in the bird. The chicken LHRH receptor is also relatively undiscriminating with regard to amino acid substitutions in positions 5 and 7. A series of LHRH analogues with pure antagonist activity in rats exhibited a spectrum of activities, from pure agonist to mixed activity and pure antagonist, in the chicken. These differences in LHRH structural requirements of the mammalian and avian receptor are reflected by a difference in molecular size of the chicken receptor (67,000) and mammalian receptor (60,000). Nevertheless, like the mammalian pituitary, the chicken pituitary does exhibit “desensitization” on prolonged exposure to LHRH.
Growth hormone: Its physiology and control
Authors: Scanes Colin G. , Lauterio Thomas J.
Published: June 2005

Growth hormone (GH) is a protein hormone produced by the somatotrophs of the anterior pituitary gland of birds and other vertebrates. The secretion of GH in birds is under hypothalamic control; it involves three peptidergic releasing factors: growth hormone‐releasing factor (GRF) (stimulatory); thyrotropin‐releasing hormone (TRH) (stimulatory); and somatostatin (SRIF) (inhibitory). In addition, there is evidence for effects of biogenic amines (including serotonin and norepinephrine) and prostaglandins at the level of the hypothalamus and possibly also the pituitary gland. In all avian species examined, plasma concentrations of GH are high in young posthatching chicks but low in the adult and embryo. The difference in plasma concentrations of GH between young and adult birds is due to both greater GH secretion and reduced clearance. The lower secretion of GH in adult birds reflects fewer somatotrophs in the pituitary, changes in somatotroph structure, and reduced GH responses to TRH or GRF administration. There is only limited data on the role of GH in birds. GH appears to be required for normal growth; acting at least in part by increasing somatomedin production. However, plasma concentrations of GH do not necessarily correlate with growth rate. For instance, in chicks with reduced growth rate owing to either goitrogen or protein deficiency in the diet, plasma concentrations of GH are elevated. GH also can influence lipid metabolism by increasing lipolysis, decreasing lipogenesis, and stimulating the uptake of glucose by adipose tissue. The physiological significance of these actions is, however, not established. In addition, GH affects the secretion of other hormones, the immune system, and perhaps also the reproductive system.
Hormonal and environmental interactions on thyroid function in the chick embryo and posthatching chicken
Authors: Kühn E. R. , Decuypere E. , Rudas P.
Published: June 2005

Recent research has focused on developmental changes in thyroxine (T4) metabolism as well as hormonal and environmental interactions upon peripheral monodeiodination. Toward the end of incubation and the time of air space membrane perforation, concentrations of 3,3′,5′‐triiodothyronine T3 increase more rapidly than T4, while reverse T3 (rT3) decreases. Administration of glucocorticoids or prolactin (hormones known to increase at the end of incubation) 2 to 3 days prior to air chamber perforation can induce this change in T4 metabolism. Attention has been focused on two major environmental factors that influence T4 concentrations in posthatch chicks. T4 disappearance rate and peripheral T4 conversion are adjusted during thermal acclimation. More T3 will be generated in cold‐exposed chickens, and more rT3 will be produced at higher ambient temperatures. Peripheral T4 metabolism acts as an independent regulation pathway but accompanies changes in hypothalamothyroid activity. Changes in thyroid hormone levels following ambient temperature changes, therefore, are the result of a balance between central and peripheral control mechanisms, depending on age of the animal and degree and duration of the temperature change. In the hen, feeding also plays an important role in the regulation of the absolute levels and daily rhythms of plasma thyroid hormones. Fasting results in an increase in circulating T4 levels, but a decrease in T3 levels, owing to a lower 5′deiodinase activity, and also abolishes the circadian circulating T3 rhythm.
Avian endocrine responses to environmental pollutants
Authors: Rattner Barnett A. , Eroschenko Victor P. , Fox Glen A. , Fry D. Michael , Gorsline Jane
Published: June 2005

Many environmental contaminants are hazardous to populations of wild birds. Chlorinated hydrocarbon pesticides and industrial pollutants are thought to be responsible for population declines of several species of predatory birds through eggshell thinning. Studies have demonstrated that these contaminants have estrogenic potency and may affect the functioning of the gonadal and thyroidal endocrine subsystems. Petroleum crude oil exerts toxicity externally, by oiling of plumage, and internally, by way of ingestion of oil while feeding or preening. Extensive ultrastructural damage to the inner zone of the adrenal, diminished adrenal responsiveness to adrenocorticotrophic hormone, and reduced corticosterone secretion rate suggest that low levels of plasma corticosterone reflect a direct effect of petroleum on the adrenal gland. Suppressive effects of oil on the ovary and decreases in circulating prolactin have been associated with impaired reproductive function. Large‐scale field studies of free‐living seabirds have confirmed some of the inhibitory effects of oil on reproduction that have been observed in laboratory studies. Organophosphorus insecticides, representing the most widely used class of pesticides in North America, have been shown to impair reproductive function, possibly by altering secretion of luteinizing hormone and progesterone. Relevant areas of future research on the effects of contaminants on avian endocrine function are discussed.
Hypotensive action of parathyroid hormone in chicken
Authors: Pang Peter K. T. , Zhang R. H. , Yang May C. M.
Published: June 2005

In a recent series of studies, the hypotensive action of parathyroid hormone (PTH) was demonstrated in several vertebrate species. In mammals, the mechanism of this direct action on specific vascular beds was studied. An increase in intracellular cyclic AMP and an inhibition of entry of extracellular calcium into the vascular tissue was correlated with the vasorelaxing action of PTH. In the present report, PTH was found to relax chicken mesenteric vessels in vitro in the presence or absence of constriction with concentrated potassium chloride (KCl). PTH produced dose‐related inhibition of the chicken vessel constricted with 10, 20, 40, or 60 mM KCl. Extracellular calcium‐dependent constriction of the chicken mesenteric artery was also decreased by PTH. An inhibitory effect was also observed with D600, a known calcium‐entry inhibitor, in the above in vitro test systems. The low affinity lanthanum‐resistant pool of calcium, which supposedly reflects the rate of calcium entry into cells, was also decreased by PTH in the control or KCl‐stimulated chicken mesenteric artery. These data suggest that PTH may produce vasorelaxation in chicken mesenteric artery by inhibition of calcium entry into cells. This vessel from the chicken seems to have a high turnover rate of calcium and may be a good model for studying the effects of substances on calcium entry in vascular smooth muscle.
In Vitro synthesis of vitellin by the ovary of the fiddler crab, Uca pugilator
Authors: Eastman‐Reks Sarah B. , Fingerman Milton
Published: June 2005

Developing ovaries of the fiddler crab, Uca pugilator, were incubated in vitro in labeled leucine, which was incorporated into the egg yolk protein, vitellin. Two primary vitellin subunits, having molecular weights of 100,600 and 123,500, were separated by SDS‐polyacrylamide gel electrophoresis. These results show that the ovary of this crab has the capacity to synthesize vitellin.
On the use of α‐amanitin as a transcriptional blocking agent in mouse embryos: A cautionary note
Authors: Kidder Gerald M. , Green A. Fred , McLachlin Jeanne R.
Published: June 2005

We have tested the effect of α‐amanitin at 10, 50, and 100 μg/ ml, on precursor uptake and incorporation into poly(A)+ RNA and poly(A)− RNA of mouse embryos on days 2, 3 and 4 of gestation. Embryos were pretreated with the inhibitor for 2 hr, then labeled for 2 hr in its continued presence. RNA fractions were separated by affinity chromatography on oligo(dT)‐cellulose. α‐Amanitin did not suppress uptake of RNA precursors at any of the concentrations tested in any stage. At 10 μg/ml, we could not detect any effect on incorporation into either RNA fraction in any stage. Only the highest concentration tested, 100 μg/ml, was effective in all stages in substantially suppressing incorporation into poly(A)+ RNA within 2 hr. Longer treatments increased the level of suppression to a maximum of about 80%. Incorporation into poly(A)− RNA was suppressed to roughly the same extent. Despite previously reported data, it cannot be assumed that α‐amanitin at concentrations less than 100 μg/ml brings about a quick interruption of mRNA synthesis in preimplantation mouse embryos.
Muscle function studies in amputated lathyritic rats
Authors: Yeager Vernon L.
Published: June 2005

This study is presented to compare two methods of evaluating changes in muscle function after amputation of the left leg at the knee. Rats were fed a 50% Lathyrus odoratus diet, which causes exostoses to develop at sites of attachment of certain muscles. The rats were on the experiment for 3, 6, or 9 weeks. Muscles of rats killed at 6 weeks were weighed to determine whether atrophy or hypertrophy had occurred. Sizes of exostoses were evaluated subjectively at each time period. The left adductor longus and quadratus femoris muscles underwent considerable atrophy and their exostoses were smaller than on the right side. The left iliopsoas increased in weight and had the larger exostosis. However, the left pectineus increased in weight but had the smaller exostosis. It is concluded that changes in muscle weights and changes in sizes of exostoses both reflect changes in muscle function, but because the two methods respond by different mechanisms, the results do not always agree.
Possible function of 17β‐hydroxysteroid dehydrogenase in preimplantation hamster embryos
Authors: Wu Jung‐Tsung , Matsumoto Paul S.
Published: June 2005

17β‐Hydroxysteroid dehydrogenase (17β‐HSD) catalyzes the interconversion of estradiol‐17β (E2) and estrone (E1). The present study is designed to investigate the following: (1) the developmental stage of hamster embryos at which 17β‐HSD activity first becomes detectable, and (2) the E1 → E2 and E2 → E1 conversion rate in the preimplantation hamster embryo. Embryos obtained from superovulated hamsters on days 1–4 were cultured in medium containing 107 ng [3H]E1 or – E2/ml and the respective conversion product, [3H]E2 or – E1, was isolated and assayed. The results show that (1) E1 → E2 conversion was active in all embryos at the rate of 0.57, 0.66, 0.54 and 0.48 fmol/embryo/hr for day 1 (one‐cell), 2 (two‐cell), 3 (eight‐cell) and 4 (blastocyst), respectively, and (2) E2 → E1 conversion was not detectable in hamster embryos. In long‐term blastocyst culture, E2 → E1 conversion becomes detectable at 25 hours and increases sharply from 25 to 47 hours. These results suggest that (1) 17β‐HSD may function mainly to convert E1 into E2 in preimplantation hamster embryos and (2) E2 → E1 conversion may become active only during and after implantation.
Cortical reaction and zona hardening in mouse oocytes following exposure to ethanol
Authors: Gulyas Bela J. , Yuan Lydia C.
Published: June 2005

Mouse oocytes were treated with 8% ethanol for 3–6 min. The rate and pathways of parthenogenetic activation, occurrence of cortical reaction, and zona solubility changes were assessed in alcohol‐treated eggs. The incidence of parthenogenetic activation was greatest (91%) after 3–4‐min exposure, and it was reduced (84%) after 5–6‐min exposure to alcohol. Also, the rate of haploid single pronucleate parthenogenones decreased and the rate of fragmented ova increased with increase time of exposure to ethanol. Ultrastructural observations showed occurrence of cortical reaction, disappearance and subsequent reappearance of short microvilli. A slight damage occurred to the ER in alcohol‐exposed ova. The zona dissolution assay utilizing äL‐chymotrypsin demonstrated decreased solubility of the zonae pellucidae after exposure to alcohol. The zona dissolution t50 increased from 0.5–2.5 min in nontreated unfertilized oocytes to about 4 h in activated ova. The t50 of in vivo fertilized eggs was 4 1/2 h. Empty zonae exposed to alcohol lysed at the same rate as nontreated control zonae did. The results indicate that activation of mouse oocytes with alcohol initiates completion of meiosis and triggers the cortical reaction, which results in subsequent hardening of the zona pellucida.
Protein synthesis by isolated pachytene spermatocytes in the absence of sertoli cells
Authors: Jutte N. H. P. M. , Jansen R. , Grootegoed J. A. , Rommerts F. F. G. , van der Molen H. J.
Published: June 2005

Isolated rat pachytene spermatocytes were incubated in chemically defined medium supplemented with pyruvate and lactate, which are known to be essential energy substrates for these germ cells. Protein synthesis by the isolated cells was investigated by means of two‐dimensional polyacrylamide gel electrophoresis. The electrophoretic patterns of (35S)‐labeled proteins, synthesized by the pachytene spermatocytes during incubation in the presence of (35S)methionine either from 0–2 h or from 24–26 h after isolation, were almost completely identical. The patterns of newly synthesized proteins of freshly isolated spermatocytes and spermatids, however, showed several stage‐specific proteins in addition to many proteins common to both spermatogenic cell types. Hence, it was concluded that a stage‐specific pattern of protein synthesis can be maintained by pachytene spermatocytes during incubation for a period of 24 h in the absence of Sertoli cells but in the presence of a proper energy source.
Decrease in the number of primordial germ cells following injection of the animal pole cytoplasm into the vegetal pole region of Xenopus Eggs
Authors: Sakata Susumu , Kotani Minoru
Published: June 2005

Effects of the egg cytoplasm on the formation of primordial germ cells (PGCs) were examined through microinjection into the subcortical cytoplasm near the vegetal pole of Xenopus laevis eggs. Injection of vegetal pole cytoplasm and physiological saline did not reduce the number of PGCs. However, the average number of PGCs in tadpoles at stage 46 decreased to about 60% of that in normal controls when the animal pole cytoplasm of fertilized eggs was injected into the intact eggs. Similar effects were observed when the animal pole cytoplasm of fertilized or unfertilized eggs was injected into eggs irradiated with a low dose of ultraviolet light. These facts suggest the possibility that inhibitor(s) of PGC formation exists in the animal pole cytoplasm of both fertilized and unfertilized eggs.
Dissociation and reaggregation of cells of Chrysaora quinquecirrha (cnidaria, scyphozoa)
Authors: Black Robert E. , Riley Gayle K.
Published: June 2005

Cells of scyphistomae, strobilae, and ephyrae were dissociated with trypsin and reaggregated. Clumping was inhibited in low Ca+ + and by puromycin, but not by collagenase or sugars. Reaggregates from the oral end of the polyp developed tentacles and mouths first and basal structures later, whereas the opposite sequence occurred with cells from the lower gastric region. Nile‐blue‐stained cells from hypostome or peduncle did not form specific structures in the reconstructed polyp, but were distributed throughout the animal. Ephyra cell aggregates showed little morphogenesis, whereas cells from presumptive ephyra tissue gave rise to structures with tentacles and multiple oral openings. Mixed reaggregates containing equal proportions of polyp and ephyra cells formed irregular structures with transparent outer layer and opaque inner cell mass, suggesting stage‐specific sorting.
Appearance of autoantigens during gonad maturation in the rainbow trout (Salmo gairdneri)
Authors: Secombes Christopher J. , Lewis Andrew E. , Needham Edward A. , Laird Lindsay M. , Priede Imants G.
Published: June 2005

Maturing rainbow trout were immunised with testis plus Freund's complete adjuvant (FCA) to determine when autoantigen(s) appear on germ cells during spermatogenesis. Only testes containing spermatozoa and spermatids developed lesions, and no other germ cell types appeared to be involved. This response was gonad specific, but showed little correlation with antibody titres to spermatozoa. The necessary conditions that allow the development of autoantigen(s) on postmeiotic cells are discussed.
Limited and specific proteolysis of the zona pellucida by acrosin
Authors: Urch Umbert A. , Wardrip Nathan J. , Hedrick Jerry L.
Published: June 2005

The proteolytic action of boar sperm acrosin on its natural substrate, the zona pellucida, was investigated. Acrosin exhibited substrate specificity for the zona pellucida and differentially hydrolyzed the glycoprotein families composing the zona pellucida. In contrast to acrosin, trypsin was a less‐specific protease in terms of zona pellucida hydrolysis.
Some determinants of cellular adhesiveness in an embryonic cell line from Drosophila melanogaster
Authors: Fausto‐Sterling Anne , Muckenthaler F. A. , Hsieh Lily , Rosenblatt Peter L.
Published: June 2005

We have examined, under a number of conditions, the aggregation behavior of Schneider Line 2 cells established originally from embryos of Drosophila melanogaster. The work presented in this paper 1) further establishes appropriate conditions for the study of cellular adhesion in Drosophila cell lines; 2) shows that the adhesive capacity of Drosophila cell line cells, under our experimental conditions, depends upon the presence of CA2+ but not Mg2+; 3) shows that Drosophila cell line cells will not aggregate in the cold; and 4) shows that trypsin treatment inhibits the aggregation of cell line cells, although high concentrations of calcium ions interfere with the action of trypsin.
cAMP in ovine oocytes: Localization of synthesis and its action on protein synthesis, phosphorylation, and meiosis
Authors: Crosby Ian M. , Moor Robert M. , Heslop John P. , Osborn Jeremy C.
Published: June 2005

In the first series of experiments, the source of cAMP in the sheep oocyte was studied. Cholera toxin was shown to be a potent stimulator of cAMP in isolated sheep oocytes, demonstrating the presence of adenyl cyclase. There was no evidence for transmission of cAMP from stimulated myocardial cell monolayers to cumulus‐enclosed oocytes even though the existence of a concentration gradient of cAMP and of intercellular communication were demonstrated. However, gonadotrophin‐stimulated follicle shells were able to induce a rise in the cAMP content of denuded or cumulus‐enclosed oocytes in the same dish, independently of cell contact. Further experiments were designed to study the effects of a cholera toxin‐stimulated rise in cAMP on the maturation of oocytes. When applied to cumulus‐oocyte complexes, cholera toxin did not block germinal vesicle breakdown (GVBD), nor the accompanying changes in protein synthesis and phosphorylation, although there was evidence for a delaying effect. There were, however, indications that the toxin was inducing abnormalities that became gross when the concentration was raised 1 μg/ml. This high concentration of cholera toxin was able to block the maturation of oocytes in intact, gonadotrophin‐treated follicles, although once again abnormalities were evident. We conclude that the role of cAMP in the maturation of the sheep oocyte is different from that proposed in the mouse.
Anhydrobiosis in nematodes: Control of carbon flow through the glyoxylate cycle
Authors: Madin Katherine A. C. , Loomis Stephen H. , Crowe John H.
Published: June 2005

During induction of anhydrobiosis the nematode Aphelenchus avenae synthesizes large quantities of trehalose and free glycerol the carbon for which apparently originates from lipid. In the present paper we show that these worms possess a functional glyoxylate cycle by which lipid is converted to carbohydrate. Furthermore, we suggest a mechanism for regulation of the pathway during induction of anhydrobiosis.
Creatine kinase isozymes in pipid frogs: Their genetic bases, gene expressional differences, and evolutionary implications
Authors: Wolff J. , Kobel H. R.
Published: June 2005

Pipid frogs possess a creatine kinase isozyme repertory with a complexity paralleled only by teleostean fish. The effects of allelic polymorphism on their isozymes as well their differential solubility and resistance to heat denaturation suggest that species of Xenopus have at least four different CK loci. Each locus has its own tissue pattern of expression. CK‐I isozymes are found only in the eye and stomach of Xenopus, in the stomach but not the eyes of Pipa and Hymenochirus, and the latter appears to have this isozyme in the liver also. The tissue expression of CK‐II and CK‐IV, respectively, resembles that of CK‐A and CK‐C of fish and that of CK‐M (muscle) and CK‐B (brain) of higher vertebrates. CK‐III shows a striking developmental transition. In Xenopus heart muscle, additional CK isozymes are present that do not appear to be heterodimers. These may represent the contributions of additional creatine kinase genes or of epigenetic modification of other isozymes.

The general tissue patterns of isozyme expression are similar but unique for each Xenopus species. The presumed allotetraploid species have essentially the same number of CK isozymes as the diploid X. tropicalis, suggesting a loss of duplicate gene expression or a cryptic expression due to coincident isozyme mobilities. It is possible that certain double banded isozymes in X. borealis and X. gilli represent the expressions of genes from a past polyploidization event.

Two other genera of Pipidae, Hymenochirus and Pipa, differ from Xenopus in that they lack the CK‐III isozyme, and that the relative electrophoretic mobilities of the CK‐II and CK‐IV isozymes are reversed.
Role of the opercularis muscle in seismic sensitivity in the bullfrog Rana catesbeiana
Authors: Hetherington Thomas E.
Published: June 2005

The inner ear of anuran amphibians appears to be exceptionally sensitive to substrate vibration. The opercularis system, consisting of an opercularis muscle running from the shoulder girdle to a movable, cartilaginous operculum lying next to the inner ear, has been hypothesized to be involved in driving these seismic responses. Removal of the opercularis muscle of adult bullfrogs, Rana catesbeiana, caused clear decreases in microphonic responses of the inner ear to vibrations from 20–250 Hz and 0.05–5.0 cm/sec2 accelerations. Degree of decrease in responsiveness was variable between individuals and between different frequencies of stimulation, ranging up to 90% reduction at certain frequencies and in certain specimens. Decreases were most marked at lower frequencies below about 50 Hz. Additional removal of the levator scapulae superior muscle, which runs alongside the opercularis muscle from the shoulder girdle to ventrolateral portions of the otic capsule, also tended to depress responses, although this effect was substantially less (generally less than 10%) and also less consistent. As the opercularis muscle appears to be derived from the levator scapulae musculature, it is speculated that primitively seismic sensitivity was enhanced by a muscular connection that could transmit motion from the forelimb to the otic region, responsiveness being further enhanced by the subsequent evolution of the specialized opercularis system.
Melanin concentrating hormone (MCH) effects on teleost (Chrysiptera cyanea) melanophores
Authors: Oshima Noriko , Kasukawa Hiroaki , Fujii Ryozo , Wilkes Brian C. , Hruby Victor J. , de L. Castrucci Ana Maria , Hadley Mac E.
Published: June 2005

The in vitro biological actions of synthetic chum salmon melanin concentrating hormone (MCH) on melanophores of the blue damselfish (a teleost), Chrysiptera cyanea, were studied. This cyclic heptadecapeptide stimulated melanosome (melanin granule) aggregation (centripetal migration) within melanophores at a threshold concentration of about 10−10 M. The action of this putative hormone was not blocked by α‐ or β‐adrenoceptor antagonists. It was concluded that the effects of MCH were direct and were not mediated indirectly through the actions of adrenergic neurotransmitters released from nerve terminals. Further evidence for this view comes from the observation that, unlike the case of neurotransmitter release, melanosome aggregation in response to MCH proceeded in the absence of calcium. The possible role of MCH in the control of color change of teleost fishes is discussed.
Achromosomal cleavage of fertilized starfish eggs treated with cyclic guanosine 3′,5′‐monophosphate
Authors: Yamada Hisafumi , Hirai Setsuro , Suzuki‐Hori Chiyo , Nagano Hiroshi
Published: June 2005

Cyclic guanosine 3′,5′‐monophosphate (cGMP) was injected into fertilized starfish eggs in order to study the effects of this cyclic nucleotide on early embryogenesis. cGMP at approximate intracellular concentrations higher than 0.05 mM causes achromosomal cleavage in the presence of 1 mM caffeine, that is, each blastomere is devoid of a nucleus but not spindle and asters. The treated embryos cleave slower than control, never form blastulae, and disintegrate just before blastulation. cAMP, dibutyryl cGMP and dibutyryl cAMP failed to cause achromosomal cleavage. These results suggest that unphysiologically high levels of intracellular cGMP inhibit in vivo DNA synthesis of fertilized starfish eggs.
A spawning female‐specific substance reactive to anti‐chorion (egg envelope) glycoprotein antibody in the teleost, Oryzias latipes
Authors: Hamazaki Tatsuo , Iuchi Ichiro , Yamagami Kenjiro
Published: June 2005

A substance with high immunoreactivity to rabbit anti‐chorion (egg envelope) glycoprotein antibody was found in liver and blood plasma as well as ovary of the spawning female medaka, while it was absent in the male and the non‐spawning female fish. This substance disappeared first from the hepatic cells of the female fish when it ceased spawning, whereas the immunoreactivity still remained in ovary and blood plasma. The relative electrophoretic mobility of the antigenic substance derived from these tissues was identical. The molecular weight and isoelectric point (pI) of the substance, as determined by polyacrylamide electrophoresis with varied gel concentrations and isoelectric focusing method, were about 60,000 and about 4.5, respectively. The substance was evidently distinct from the unreactive band of probable vitellogenin (ca 420,000 and pI, ca 3.8–4.0) which was found in blood plasma of the spawning female. In ovary sections, cytoplasm of the oocyte at the initial stage of chorion formation, containing neither vitellogenin nor egg yolk, showed a strong immunoreactivity. Cytoplasm of the oocytes, later than the vitellogenic stage, exhibited little immunoreactivity. Changes of this substance in connection with the spawning cycle strongly suggest that this substance is related to oogenesis.
Localization of 3H‐norepinephrine binding sites in the trout gill
Authors: Nekvasil Nancy P. , Olson Kenneth R.
Published: June 2005

Tritiated norepinephrine (Nepi) or Epinephrine (Epi) was perfused through isolated gills of rainbow trout (Salmo gairdneri) and the affinity of vascular tissues for the amines examined by autoradiography. Pillar cells and certain endothelial cells in the filamental sinus accumulate 3H‐Nepi extensively. The afferent and efferent filamental arteries and filamental nutrient vessels did not bind 3H‐Nepi. Pillar cell and venous endothelial accumulation is selective for Nepi; Epi is not accumulated by these cells, and Nepi uptake can be inhibited by imipramine. These results suggest that pillar and venous endothelial cells are involved in regulation of plasma Nepi.
Induction of deer antlers by transplanted periosteum I. Graft size and shape
Authors: Goss Richard J. , Powel Robert S.
Published: June 2005

When discs of frontal periosteum from presumptive antler sites of 6–8 month old male fawns of the fallow deer are grafted beneath the foreleg skin, they will differentiate into pedicle bones and induce small antlers in the overlying integument. These antlers shed their velvet in the fall, and in succeeding years are replaced by larger outgrowths not exceeding 7 cm in length. Periosteal transplants 1.5 cm in diameter gave rise to ectopic antlers in 100% of the grafts, while discs measuring 1.05 cm, 0.75 cm and 0.4 cm did so in only 20% of the cases. Conversely, the donor sites produced antlers in 20–23% of the cases following removal of 1.05 cm or 1.5 cm of periosteum, while 80% and 100% grew antlers after deletions of 0.75 cm and 0.4 cm discs of periosteum, respectively. Semicircular grafts of periosteum induced antler development in most cases, especially when derived from the lateral halves of the antlerogenic region on the frontal bone. These findings confirm that the histogenesis of a deer's first pedicle and antler resides in the frontal periosteum over an area about 1.5 cm wide. They also show that leg skin is capable of antlerogenic development under the inductive influence of frontal periosteum, and that integumental wounding may enhance inductive interactions.
Termination of seasonal breeding in a weaver finch, Ploceus philippinus: Role of photoperiod
Authors: Chakravorty Krishna , Chandola‐Saklani Asha
Published: June 2005

Seasonal gonadal regression in the photoperiodic weaver finch Ploceus philippinus occurs in the late summer despite the presence of long days. Earlier studies indicated a decline in photosensitivity in late summer, which might explain the failure of birds to respond to long days, resulting in gonadal regression. Results obtained in the present study suggest that 1) birds become refractory only to the stimulatory day lengths experienced in nature (longest day at 25° N 13.34 hr) and not to all long day lengths as in many other photoperiodic passerine species 2) birds become refractory in accordance with the day length they experience during the growth phase of the gonadal cycle. Thus birds held on 12 L/12 D become refractory to 12 L/12 D but are photosensitive to longer day lengths. Similarly, birds on natural day length become photorefractory to the longest day but are sensitive to higher day length, viz 15 L/9 D. 3) The long summer day lengths experienced in nature might cause the seasonal decline in photosensitivity.
Temperature‐sensitive mutations causing reversible paralysis in Caenorhabditis elegans
Authors: Hosono Ryuji , Kuno Sigeru , Midsukami Minoru
Published: June 2005

A method has been developed for the isolation of temperature‐dependent paralytic mutants of the nematode Caenorhabditis elegans, based on a screening procedure using short‐time exposure to 30°C. Of ten mutants isolated, eight lose their motilities between 30°C and 33°C without prominent changes in body forms. The other two strains that are mainly described in this report are accompanied by alterations in body forms. One mutation, cn101, is recessive and an allele of cha‐1. The cn101 mutant shows reversible paralysis at 30°, accompanied by a hypercontracted and coiled body form. At the restrictive temperature, the strain is resistant to all tested inhibitors of acetylcholinesterase (AChE). Another mutation, designated mah‐2 (cn110), is a sex‐linked semidominant that is mapped as 0.6 map units left of dpy‐6. The cn110 mutant is rapidly paralyzed at the restrictive temperature and has a straight and rigid body form; the mutant rapidly recovers when the temperature is lowered. No disorganization of the muscle structure was detected by polarized light and electron microscopic inspection.