bluuebunny/crossref_metadata_2025 huggingface dataset:
An acrosome reaction in natantian sperm
Authors: Yudin Ashley I. , Clark Wallis H. , Kleve Maurice G.
Published: June 2005

Sperm of the natantian Sicyonia ingentis are highly polarized with a conical cap and single spike extending from a spherical main body. Previous studies have shown the acrosome consists of two periodic acid‐Schiff‐positive cap components and the spike. During sperm‐egg interaction the spike is lost and the cell dehisces to expose the components of the acrosome, which lie directly apposed to the egg surface. Treatment of sperm with ionophore A23187 initiates this reaction and facilitates sequencing of the reaction. The ionophore‐induced reaction begins with retraction of the spike and concomitant swelling of the cap. These events result in the opening of the cap and exposure of the internal acrosomal components which become the new anterior surface of the sperm.
Effects of divalent cations on in vitro maturation of bovine oocytes
Authors: Leibfried Lorraine , First Neal L.
Published: June 2005

Lowering the external concentrations of both Mg+2 and Ca+2 caused failure of meiotic resumption invitroof bovine, oocyte‐cumulus complexes. Lowering of external Ca+2 levels singly had no effect on either meiotic resumption or completion of the first meiotic division. Lowering of external Mg+2 concentration on meiotic resumption invitro when Ca+2 was present, did interfere with the completion of the first meiotic division. The result was arrest of oocyte matuaration between germinal vesicle breakdown and formation of the first metaphase plate.
Salt and water balance in the oligohaline clam, Rangia cuneata III. Reduction of the free amino acid pool during low salinity adaptation
Authors: Henry Raymond P. , Mangum Charlotte P.
Published: June 2005

During adaptation to low salinity (from 20 to 2 ppt), the estuarine clam Rangia cuneata reduces the size of a pool of free amino acids in adductor muscle fibers, presumably to control cell volume. The levels of both free amino acids and ammonia in the blood increase, but the rise in free amino acids is much greater. While free amino acid excretion is never very great, ammonia excretion rises shortly after valve opening and remains high throughout the period of adaptation Evaluation of the convection capability of the cardiovascular system suggests that the rate of free amino acid excretion cannot explain the loss of these substances as such from the tissues. Conversely, the levels of ammonia in blood cannot explain the rate of excretion. We suggest that most of the free amino acids are extruded from the cells and transported to a central site of deamination, from which ammonia is excreted. In situ deamination in the various tissues may occur after the initial stages of low salinity adjustment, but it never appears to explain the major fraction of ammonia excretion.
Changes in pituitary responsiveness to luteinizing hormone‐releasing hormone during an annual cycle in the domestic duck, Anas platyrhynchos L.
Authors: Balthazart J. , Willems J. , Hendrick J. C.
Published: June 2005

On four occasions during an annual cycle, 5–7 male domestic ducks were injected with two different doses (5 and 20 μg) of synthetic luteinizing hormone‐releasing hormone (LHRH) to study the possible changes in responsiveness of the pituitary. The luteinizing hormone (LH) and the follicle‐stimulating hormone (FSH) were measured in the plasma samples collected after these injections. The induced release of LH changes from one period of the year to another, being minimum in March at the height of the, reproductive season. The LHRH injection also induces the release of some FSH but only in limited amounts. The changes in pituitary responsiveness to LHRH are negatively correlated to changes in the circulating LH level (it is high when the plasma LH is low and vice versa). This suggests that the hypothalamic synthesis and release of LHRH must also change during the year.
Electrical activity in cardiac mutant axolotl hearts
Authors: Epstein Miles L. , Lemanski Larry F.
Published: June 2005

Electrical recordings from the hearts of both cardiac lethal mutant and normal embryos showed the presence of action potentials conducted over the heart tube. Ionic coupling and gap junctions also were observed in both. These results suggest that the absence of heart function in mutant embryos does not result from a defect in electrical activity.
Effector mechanism in the response of Schistosoma mansoni miracidia to snail‐conditioned water
Authors: Roberts Thomas M. , Linck Richard W. , Chernin Eli
Published: June 2005

Schistosoma mansoni miracidia respond to snail‐conditioned water (SCW) by sharply increasing their rate of turning when they encounter abrupt decreases in stimulant concentration (Roberts et al., '79). We examined the role of the cilia and the subepithelial muscles in the turning behavior of stimulated miracidia. Several lines of evidence indicated that miracidia do not turn by altering their ciliary beat. Ciliary beating on detergent‐treated miracidia was reactivated using solutions containing ATP and Mg2+. These organisms were unable to turn spontaneously, a characteristic of live miracidia. Several divalent cations which stimulate increased turning of intact miracidia failed to support ciliary reactivation of detergent‐treatedor, ganisms. Further, intact miracidia increased their rate of turning in gradients of Mg2+, but detergent‐treated organisms swimming in reactivation solution did not turn in Mg2+ gradients.

High speed cinematography of intact miracidia swimming in gradients of SCW or Mg2+ illustrated that turning is invariably accompanied by flexion of the body. This bending occurred only at the transverse interciliary ridges between the first, and second, and second and third tiers of ciliated plates. Flexion was not observed at the interciliary ridge between the third and fourth tiers of plates, suggesting that miracidia turn by contracting specific portions of their subepithelial musculature.
Color and color adaptation of the European tree frog, Hyla arborea
Authors: Nielsen Hans Ingolf
Published: June 2005

The colors and color adaptation of the European tree frog, Hyla arborea, have been investigated by means of reflectance microspectrophotometry. The results are compared to those previously published on Hyla cinerea.

The two species have a number of colors in common (yellow green, light green, green, dark green, black‐green, and olive green), while grey colors are assumed only by Hyla arborea and lemon yellow (olive yellow) only by Hyla cinerea. The physical qualities of these colors and the corresponding states of the chromatophores are presented and discussed.

Hyla arborea apparently adapts better, and thus more predictably to its background than Hyla cinerea (as judged with the eyes of man). Both adapt to a certain degree to the lightness of the background, but the former also shows a certain adaptation to the purity, and it has a greater ability to change its hue, although a definite adaptation to background hue could not be determined.

In Hyla arborea, the changes in the xanthophores seem to be paralleling those of the iridophores, but the changes in the melanophores appear to be independent. For this species, as well as for Hyla cinerea, more than one factor must therefore be regulating the adaptive color change. A number of possibilities are discussed.
Development of naked growing mouse oocytes in vitro
Authors: Bachvarova Rosemary , Baran Madelyn M. , Tejblum Ana
Published: June 2005

Half grown oocytes were released from follicles of 7‐day‐old mouse ovaries during overnight culture. Naked oocytes free of attached follicular cells were cultured in MEM plus 10% fetal calf serum over the developing monolayer of ovarian cells. Oocytes increased in diameter for a period of at least a week at 1.6 μ per day, or 70% of the in vivo growth rate. The ultrastructure of cytoplasmic organelles in cultured growing oocytes was normal. During the second week, about 35% underwent spontaneous fragmentation, and at least 10–20% resumed meiotic maturation. We conclude that a significant fraction of naked oocytes reached a functional state comparable to that of normal full grown oocytes at a rate approaching the in vivo rate.

Free oocytes with attached cells grew to a larger average diameter than naked oocytes, and incorporated 3H‐leucine 75% more rapidly. Naked oocytes cultured in the absence of ovarian cells did not grow, and died when pyruvate was omitted from the medium. Naked oocytes did not grow when cultured over primary mousefibroblasts, L‐cells, CHO cells, or hepatoma cells. Naked oocytes separated from the monolayer of ovarian cells by a 0.7 mm layer of agar grew at 60% of the rate of control oocytes.
Cell to cell contacts mediating mating‐type dependent recognition(s) during the preconjugant cell interactions of Oxytricha bifaria (ciliata, hypotrichida)
Authors: Ricci Nicola , Cetera Rosanna , Banchetti Rosalba
Published: June 2005

The direct conjugant interactions leading to pair formation (“Visible Reaction”) of Oxytricha bifaria were studied by means of enzymes acting on the cell surface. They are able to interrupt at successive stages the cell interactions occurring during the Visible Reaction. The results show that: 1) mating type specific cell recognition occurs during the Visible Reaction; 2) this recognition is a prerequisite for pair formation; and 3) cell to cell contacts leading to membrane fusion play a critical role in such a recognition.

The system of the preconjugant interactions in O. bifaria is composed of, at least, two successive and distinct stages, each playing separate roles in the general strategy of conjugation: A) a waiting period and B) a Visible Reaction. During the waiting period, complementary cells interact from a distance by means of mating type specific soluble factors (gamones) (Esposito et al., '76), and become “ready” to contact other similarly “ready” cells. By means of direct interactionsmediated by mating type specific cell‐to‐cell contacts during the Visible Reaction, a cell can recognize the contacted potential partner as belonging either to a complementary mating type (“go ahead”), or to its own mating type (“interrupt the conjugation program”). A general model of preconjugant interactions in ciliates is briefly discussed.
Lactate dehydrogenase isozymes in the genus Xenopus: Species‐specific patterns
Authors: Vonwyl E. , Fischberg M.
Published: June 2005

The LDH isozymes of 13 species and subspecies of the genus Xenopus have been analysed electrophoretically. In seven species and subspecies, five isozymes were found as in most vertebrates. The remaining species display more than five bands.

The gene which codes for the A subunit shows little variability. With one exception (X.fraseri), all species with 36 chromosomes and X.tropicalis with 20 chromosomes possess the same A gene or at least a gene product with the same mobility. In contrast to this, the gene which codes for the B subunit differs in all but one case, thus producing species‐specific isozyme patterns.

An allelic polymorphism at the LDH‐B locus in an X.laevis subspecies was found. In heterozygotes, the expected 15 isozymes can clearly be visualized. Since X.laevis can be considered as being tetraploid in respect to X.tropicalis, the occurrence of three genotypes in the offspring of a single pair mating gives evidence that one LDH‐B locus was rendered silent during evolution.
Anhydrobiosis in nematodes: Biosynthesis of trehalose
Authors: Loomis Stephen H. , Madin K. A. C. , Crowe John H.
Published: June 2005

The pathway for the synthesis of trehalose in Aphelenchus avenae was demonstrated. As in other systems, the enzymes involved in the synthesis of trehalose of A. avenae were found to be trehalose phosphate synthetase (TPS) and trehalosephosphate phosphatase (TPP). Some of the characteristics of trehalose phosphate synthetase were studied. It was found that the rate limiting step in the reaction is catalyzed by TPS. Partially purified TPS was specific for UDPG as the glucosyl donor, and showed a pH optimum of 8.0. The partially purified enzyme has a Km of 0.6 mM and a Vmax of 2.2 × 10−3 μmoles/mg protein min for glucose‐6‐phosphate, and a Km of 2.4 mM and Vmax of 2.5 × 10−3 μmoles/mg protein minfor UDPG.
Anhydrobiosis in nematodes: Control of the synthesis of trehalose during induction
Authors: Loomis Stephen H. , O'Dell Steven J. , Crowe John H.
Published: June 2005

Control of the synthesis of trehalose during the induction of anhydrobiosis was examined. Kinetic parameters for TPS did not change during the induction, indicating that there was no de novo synthesis of an isozyme. TPS activity doubled in the presence of a mixture of Na+, K+, Mg++, and Ca++ at concentrations normally found in the worms during induction. The concentration of glucose‐6‐phosphate increased from about 2 mM in wet worms to about 12 mM at the end of induction, and the concentration of UDPG increased from about 1 mM in wet worms to about 9 mM at the end of induction. The concentration of UDPG was found to be rate limiting. Trehalase activity decreased by half during the induction period. The significance of these data as related to the control of the synthesis of trehalose was discussed.
Pattern regulation of mesoderm in transplanted and supernumerary limbs of the cockroach. I. The final morphology
Authors: Steinbach Paul A. , Josephson Robert K.
Published: June 2005

Muscles, nerves, and tracheae were examined histologically in clusters of three limbs arising from single mesothoracic leg sockets in the cockroach, Periplaneta americana. The three‐limbed preparations were produced by amputating a normal legand replacing it with a contralateral leg from a donor animal, with the anterior‐posterior (A‐P) axis of the graft reversed relative to the A‐P axis of the host. After a few molts, two supernumerary limbs develop from the host/graft junction, one anterior and one posterior to the graft. Three to nine months after the operation, femurs from the supernumerary and graft limbs possess identifiable muscles which are, however, not as well developed as those of normal limbs. Supernumerary coxae rarely possessidentifiable musculature, but distal regions of the transplant coxae contain muscles of nearly normal morphology. Near the host/graft junction, the coxal muscles are disorganized, producing a proximal to distal gradient in muscle organization within thecoxa. The extensive disorganization near the host/graft junction is primarily a result of the reversed axis, since in grafts of ipsilateral limbs without axis reversal, there is considerably less muscle disorganization near the host/graft junction. Large, nerves and large tracheae were often located in supernumerary and graft femurs and in graft coxae in approximately the same positions as in normal limbs.
Properties of pyruvate kinase and flagellar ATPase in rabbit spermatozoa: Relation to metabolic strategy of the sperm cell
Authors: Storey Bayard T. , Kayne Fredrick J.
Published: June 2005

Rabbit sperm pyruvate kinase remains bound to the cell structure of hypotonically treated mature rabbit epididymal spermatozoa (HTRES). It displays kinetic behavior very similar to that of rabbit muscle pyruvate kinase with regard to KM values for substrates, activation by monovalent and divalent cations, inhibition by phenylalanine which is reversed by alanine, and lack of activation by fructose‐1,6‐biphosphate. The flagellar ATPase also remains bound to the cell structure of HTRES, whosemotility may be reactivated by a source of ATP. It requires Mg+2 for activity; the KM for both ATP and Mg+2 is 0.2 mM, implying that MgATP is the substrate. The ATPase activity is not inhibited by ouabain, oligomycin, or vanadate, which also do not affect reconstituted motility, and is not affected by cyclic AMP in the presence of an inhibitor of phosphodiesterase. The activities of pyruvate kinase and the flagellar ATPase in a given preparation of HTRES are comparable. Rabbit, spermatozoa have a metabolic strategy which is very similar to muscle cells. This suggests that the major use of the sperm cell's metabolic machinery is maintenance of energy for the contractile work of motility and that only minor amounts of metabolicenergy appear to be consumed in other reactions, including those involved in fertilization.
Hemoglobin polymorphism in adult cutthroat trout, Salmo clarkii
Authors: Braman J. C. , Stalnaker C. B. , Klar G. T. , Farley T. M.
Published: June 2005

Hemoglobin polymorphism was detected in a population of adult cutthroat trout by employing starch gel electrophoresis. Variation occurred only in the cathodally migrating hemoglobins. Six electrophoretic patterns were assumed to be present; however, the existence of a greater degree of complexity has not been ruled out. Eight of the 93 adult cutthroat trout sampled displayed a hemoglobin electrophoretic pattern identical to that obtained from adult rainbow trout.
Effects of cocaine on melanophore responses to catecholamines and KCl in the isolated caudal fin of the marine goby, Tridentiger trigonocephalus
Authors: Katayama Heizaburo
Published: June 2005

Effects of cocaine on melanophore responses to catecholamines and KCl were investigated in the isolated caudal fin of fish to obtain evidence for the neuronal uptake of the catecholamines and the released adrenergic transmitter in the melanophore nerve. In the presence of 10−4M cocaine, pigment aggregation responses of normal melanophores to l‐noradrenaline (NA) and l‐adrenaline (A) were augmented, while aggregation responses to dopamine (D) and isoprenaline (Iso) were partly suppressed. Immediately after the cocaine (10−4M) treatment, the sensitivity of the normal melanophores to NA or A was greatly enhanced and aggregation responses to these catecholamines were greatly augmented. This is probably due to the blocking effect of cocaine on the neuronal uptake of the catecholamines. Such supersensitivity to the catecholamines of the normal melanophores was approximate to that of denervated melanophores. Probably, the supersensitivity of the denervated melanophores to NA and A mainly results from impairment of the neuronal uptake of the catecholamines. The sensitivity of melanophores to D or Iso was somewhat enhanced after denervation. After pretreatment with 10−4M cocaine, the pigment aggregating response to KCl was augmented. In the presence of 10−4M cocaine, pigment dispersion in the physiological solution was slowed down when the pigment had been made to aggregate by KCl or administered NA. It is highly probable that the exogenous NA, A, or the released adrenergic transmitter is taken up by the melanophore nerve endings. D and Iso are also probably taken up but only to a very limited extent.
Strategy of oxidative metabolism in bull spermatozoa
Authors: Storey Bayard T.
Published: June 2005

Hypotonically treated bull epididymal spermatozoa (HTBES) were prepared by the same technique used for hypotonically treated rabbit epididymal spermatozoa (HTRES) in order to compare the mitochondrial activities of the bull gamete to those of the rabbit gamete. Bull sperm mitochondria oxidize pyruvate plus malate, lactate plus malate, and acetyl‐L‐carnitine plus malate with energy coupling. The rate of O2 uptake by HTBES with pyruvate plus malate is more rapid than lactate plus malate. Bull sperm mitochondria also oxidize glutamate plus malate, L‐3‐glycerolphosphate, and palmitoyl CoA plus carnitine as well as palmitoyl‐L‐carnitine. The first mitochondrial activity enables bull sperm to utilize the malate/aspartate shuttle as well as the lactate/pyruvate shuttle to transfer reducing equivalents from NADH produced by glycolysis in the cytosol to the mitochondria for complete oxidation by O2. The latter two activities enable bovine sperm to utilize endogenous lipids and phospholipids for energy metabolism. Rabbit sperm mitochondria lack these three mitochondrial oxidative activities but have maximal oxidative activity with lactate as substrate (Storey and Kayne ('77). Bull spermatozoa are equipped metabolically for survival in the bovine oviduct lumen, which has a low content of oxidizable substrate, while rabbit spermatozoa are equipped for survival in the rabbit oviduct lumen, which has a high lactate content. The hypothesis was proposed that mitochondrial activities of sperm of a given species are adapted to the substrate content of the oviduct lumen of that species and so have predictive value concerning oviduct lumen content.
Neurobiology of the stoloniferan octocoral Clavularia sp.
Authors: Satterlie Richard A. , Case James F.
Published: June 2005

Electrical impulses representing a colonial conducting system were recorded from polyp oral disks of Clavularia sp. with extracellular suction electrodes. The colonial system is through‐conducting and initiates colony‐wide polyp contraction and withdrawal. Activation of polyp musculature is dependent upon stimulus (colonial impulse) number and frequency. A synaptic nerve net is present throughout the ectoderm of the colony and polyps and presumably represents the colonial system from which impulses were recorded.

Each polyp can bend, feed, and withdraw independently, and this activity does not spread to neighboring polyps. Application of beef liver extract to polyp tentacles induces oral‐directed flexions of the stimulated tentacles (feeding responses). A burst of electrical impulses, recorded from polyp oral disks, accompanies the feeding responses. Putative tentacular sensory structures, examined by transmission and scanning electron microscopy, consist of ciliary cone‐nematocyte complexes. Each complex has a central nematocyte, bearing an apical cilium, and several surrounding cells, providing microvilli to the cone.
Transcriptional activity in lysates of cultured mesenchymal cells from embryonic tooth germs
Authors: Kestler D. P. , Kollar E. J. , Rossomando E. F.
Published: June 2005

Mesenchymal cells isolated from the papilla of embryonic tooth germs of the mouse were cultured in a complex medium for five to six days. Liquid nitrogen lysates, prepared from these cells, incorporated nucleoside monophosphates into a cold acid‐insoluble product. The product was sensitive to RNase and no product was formed if the lysate was pretreated with DNase. The reaction was sensitive to EDTA and, in its presence, optimum activity was obtained with 2 mM MgCl2. On sucrose gradients, the reaction product was distributed between two broad peaks; one centered about 18S and the other above 28S. The RNA polymerase inhibitor α‐amanitin inhibited approximately 50% of the activity at a concentration of 10 μg/ml.
Metabolic consequences of accelerated urea synthesis during seasonal dormancy of spadefoot toads, Scaphiopus couchi and Scaphiopus multiplicatus
Authors: Jones Ronald M.
Published: June 2005

Scaphiopus couchi newly emerged from natural dormancy produce urea at a greater rate than dormant toads kept in moist soil. Energy budgets during dormancy of Scaphiopus couchi and S. multiplicatus were calculated by measuring protein, carbohydrate, lipid, ash, and DNA content of newly emerged toads and toads near the end of the natural activity period. Scaphiopus couchi uses 17% of the protein, 36% of the lipid, and 28% of the total energy reserves available at the start of dormancy, and S. multiplicatus uses 32% of the protein, 62% of the lipid, and 51% of the total energy reserves. If all of the nitrogen derived from protein catabolism were accumulated as urea, the minimum difference in body fluid concentrations before and after dormancy would be 167 mM for S. couchi and 341 mM for S. multiplicatus. Because these predicted increases are greater than normally observed in the body fluids of spadefoots at the end of dormancy, the toads apparently are obtaining sufficient part of their nitrogen wastes. Simultaneous O2 consumption, CO2 production, and nitrogen waste production measurements provide evidence for a shift from lipid to protein metabolism in S. couchi when osmotically stressed. During osmotic stress, S. couchi does not simultaneously achieve the reduced levels of O2 consumption associated with dormancy, and increased protein catabolism and urea synthesis. Feeding experiments show that protein, carbohydrate, and lipid and replenished in newly emerged. S. couchi in proportion to their representation in the diet.
Volume changes associated with hydrolysis of ATP by teleost branchial (Na+ + K+)‐ATPase and Mg2+‐ATPase
Authors: Pfeiler Edward
Published: June 2005

The effects of hydrostatic pressure on branchial NaK‐ATPase and Mg‐ATPase activities of Scorpaena guttata (shallow‐water fish) and Anoplopoma fimbria (deep‐water fish) were used to calculate volume changes that occur during catalysis. The apparent activation volumes (ΔVs) of the NaK‐ATPase, determined at test pressures between 68 and 340 atm, were positive and not significantly different in the two species. ΔV for the Mg‐ATPase of S. guttata was also positive but significantly lower than the ΔV value for the NaK‐ATPase. Negative values for ΔV were obtained for the Mg‐ATPase of A. fimbria. Solubilization of the enzymes from gill microsomes of A. fimbria with Lubrol WX had no effect on ΔVs. NaI treatment of gill microsomes resulted in significant changes in ΔV for both enzymes in A. fimbria and in the Mg‐ATPase of S. guttata. The effect of hydrostatic pressure on Kmfor ATP was used to estimate apparent ATP binding volume (ΔVbind.). The Km values obtained at 1 atm for the Mg‐ATPase and NaK‐ATPase of A. fimbria (0.030 and 0.043 mM, respectively) were approximately an order of magnitude lower than those of S. guttata(0.24 and 0.28 mM, respectively). High hydrostatic pressure (340 atm) produced an increase in Km in the NaK‐ATPase of both species, indicating that ΔVbind. is positive. The Km of the Mg‐ATPase in S. guttata was relatively insensitive to pressure (small positive value for ΔVbind.) where it decreased at high pressure in A. fimbria, yielding a large negative value for ΔVbind..
A technique for the in vitro perfusion of bovine parathyroid glands
Authors: Latmen Neal S.
Published: June 2005

A system for the in vitro perfusion of bovine parathyroid glands was developed. The glands were perfused at 1 ml/minute with oxygenated Hanks balanced salt solution buffered with sodium bicarbonate to a pH of 7.4 at 37°C. These glands remained functionally stable for seven to eight hours. The secretory rate of immunoreactive parathyroid hormone varied inversely with the calcium concentration of 3.0 to 6.0 mg/100 and became nonsuppressible at calcium concentrations above 6.5 mg/100 ml. Therefore, the glands are thought to be responsive to stimuli. A loss of functional stability can usually be detected by an increase in perfusion pressure. The samples of effluent containing immunoreactive parathyroid hormone remained stable (immunoreactively) for six months when stored at −70°C. This system provides a valid method for monitoring dynamic, minute‐to‐minute changes in parathyroid secretory activity.
Changes in protein synthesis following fertilization of the mouse ovum
Authors: Chen H. Y. , Brinster R. L. , Merz E. A.
Published: June 2005

A quantitative method utilizing double isotope labeling with 3H‐methionine and 35S‐methionine and two‐dimensional polyacrylamide gel electrophoresis was employed to compare synthesis of 95 individual proteins in fertilized and unfertilized mouse ova. It was found that six proteins had significantly (P < 0.05) increased rates of synthesis while 11 proteins had significantly (P < 0.05) decreased rates of synthesis following fertilization. The studies indicate that there are changes in the synthetic rates of a much larger number of proteins at the time of fertilization than expected from previous reports.
Catalyic and regulatory properties of muscle pyruvate kinase from Cancer magister
Authors: Guderley Helga , Hochachka Peter W.
Published: June 2005

Despite the marked changes that crustacean muscle undergoes during the molt cycle, pyruvate kinase is present as the same from throughout the molt cycle. This pyruvate kinase was subject to feed‐forvard activation by fructose‐1, 6 bisphosphate (FBP) as well as feed‐back inhibition by MgATP. The enzyme showed a high affinity for phosphoenolpyruvate (Km = 0.1 mM) but showed no cooperativity in substrate binding. The addition of 0.05 mM FBP reduced the PEP Km to 0.05 mM. MgATP inhibition showed a Ki of 1.8 mM versus PEP. The inhibition due to MgATP could be reversed by FBP. Various other compounds inhibited the enzyme, including citrate, α‐ketoglutarate, tryptophan, and malate, although at rather high levels. Measurements of the reversal of this pyruvate kinase, taken together with the low levels of phosphoenolpyruvate carboxykinase and pyruvate carboxylase, predict only minimal levels of gluconeogenic flux in crustacean muscle.
Active calcium extrusion by Amoeba proteus
Authors: Prusch Robert D.
Published: June 2005

Cytoplasmic calcium levels in the amoeba are maintained at very low levels. Previous studies have suggested that this is accomplished by a system of cytoplasmic storage sites. Evidence is presented here that Amoeba proteus capable of actively extruding calcium across the plasmalemma. Active calcium extrusion is then responsible in part for the maintenance of low cytoplasmic calcium activities and may be involved at least indirectly in such basic cellular process as locomotion and pinocytosis in the amoeba.
Some observations on the sex differentiation of an entoproct, Barentsia discreta (Busk)
Authors: Mukai Hideo , Makioka Toshiki
Published: June 2005

The differentiation of sex and the morphology of gonads of a colonial entoproct Barentsia discreta were studied with living animals and histological preparations. Each zooid is unisexual; the colony is monoecious, containing both male and female zooids. During the early part of the breeding season, male zooids exceed female zooids in number. Even at the peak period (August and September), male zooids are predominant along the distal portions of actively growing stolons. When the calyx of a zooid is replaced through regeneration, a change of sex may occur. Some double monsters with a male and a female calyx were found. In both sexes, the reproductive system consists of a pair of gonads and a common gonoduct. In the male, the spermiduct is surrounded by some atrophied glandular cells. At the junction of the testis and the spermiduct, some epithelial cells are specialized to bear long cilia, which are extended into the testicular lumen. Immature testes often contain some previtellogenic oocytes. In the female, the oviduct is accompanied by glandular cells and is divided distally into a pair of small ducts. The small oviduct connects with the ovary by a large cell, called the “plug”‐cell. The largest oocytes occupy the blind end of the ovary, where the ovarian tissue contains many mature spermatozoa. The egg becomes fertilized in the ovary and is ovulated at the metaphase of the first meiotic division. Polar body formation and subsequent embryogenesis proceed in the vestibule. Seven or eight days seem to be needed from ovulation to larval release.
Further evidence for haploid gene expression during spermatogenesis: Heterogeneous, poly(A)‐containing RNA is synthesized post‐meiotically
Authors: Erickson Robert P. , Erickson Jeanne M. , Betlach Charles J. , Meistrich Marvin L.
Published: June 2005

Mouse testicular cells labelled in vivo with 3H‐uridine for 1 hour were separated into enriched cell populations representing different stages of spermatogenesis by centrifugation in an Elutriator rotor. RNA extracted with phenol and chloroform was sized by electrophoresis on 2.4% acrylamide gels. The percentage of newly synthesized RNA which was not ribosomal RNA (or its precursors) and was not transfer RNA, was higher in early postmeiotic, as compared to late premeiotic, stages. RNA was also extracted from fractionated cells in the presence of guanidinium chloride and the proportion of total 3H‐RNA‐containing poly(A) sequences was determined by binding to an oligo‐(dT)‐cellulose column. RNA that bound in 0.5 NaC1 was eluted with low salt buffer and reapplied twice more, after heating each time in DMSO to disaggregate any non‐poly(A)‐containing RNA. The percentage of newly synthesized RNA which contained poly(A) did not decrease in early postmeiotic, as compared to late premeiotic, stages. We suggest that at least some part of the 6–15S 3H‐RNA and 3H‐poly(A)‐containing RNA represents mRNA(s) transcribed postmeiotically in haploid germ cells.
Influence of temperature and unstirred layers on the kinetics of glycine transport in isolated gills of Mytilus californianus
Authors: Wright Stephen H. , Becker Steven A. , Stephens Grover C.
Published: June 2005

The effect of temperature on the kinetics of glycine influx in isolated gills of Mytilus californianus was studied. Increases in temperature resulted in significant increases in the J for glycine influx over the range 7–23° C (Q10 = 5). Concomitant with this increase in J was an increase in experimentally determined Kt, from 23 μM to 134 μM. The relationship between changes in J and measured Kt was adequately described by an equation that takes into account the influence of unstirred layers on the kinetics of carriermediated transport. Use of this equation indicated that the changes in measured Kt could be explained by the presence of an unstirred layer approximately 400 μm thick over the transporting surfaces(s) of the isolated gill, and that the “true” Kt of the transport process is 1 μM. The very low values Kt for amino acid uptake measured in intact mussels (1–3 μM) are revealed to be the product of transport processes of high affinity for substrate and a perfusion system which effectively minimizes the influence of unstirred layers, thereby permitting efficient utilization of substrate at the low concentrations characteristic of these animals' environment.
Fluorometric detection of implantation sites in rats
Authors: Hicks J. J. , Gil‐Recasens M. E. , González‐zamudio J.
Published: June 2005

A new fluorescent technique is proposed for detecting implantation sites in the rat, based on the binding capacity of tetracycline. Both intraluminal (20 μg/kg) and intravenous (8.3 mg/kg) administrations of tetracycline permit the macroscopic visualization (under 366 nm of ultraviolet light) of implantation sites, since they show a lower flurescence (LFS) than the remaining endometrium (FS). Greater binding a tritiated tetracycline was observed in nonimplantation sites (176 to 56 × 103 dpm/mg protein) than in implantation sites (P < 0.05).
Initiation of cleavage in Oryzias latipes eggs injected with centrioles from sea urchin spermatozoa
Authors: Ohta T. , Iwamatsu T.
Published: June 2005

Cleavage‐initiating activity of various biological materials was tested by microinjection into unfertilized eggs of Oryzias latipes. Injection of intact sea urchin spermatozoa, their flagellum‐ and centriole‐fractions induced cleavage of unfertilized eggs. On the contrary, injection of the suspension medium alone did not induce cleavage. In the process of a ster formation elicited by injection, fibrous structures appeared first within a dispersing mass of the injected fraction, and they then developed into a few large or many small astral structures. Eggs which cleaved within 2 hr after injection displayed only a few large asters within a thickened blastodisc. In the non‐cleaved eggs, only many small asters appeared throughout the blastodisc.

These experiments indicated that the isolated centrioles from sea urchin spermatozoa can induce aster formation and cleavage in the fish.
Role of neural retina and vitreous body during lens regeneration: Transplantation and autoradiography
Authors: Gulati Adarsh K. , Reyer Randall W.
Published: June 2005

The trophic influence of neural retina in regeneration of the lens from dorsal iris is well known. The first part of this study involved transplantation of dorsal iris pieces into various intra‐ocular positions in order to determine the field of action of the neural retina. The most favorable location for lens regeneration was the pupillary space, closely followed by the vitreous chamber. Lens regeneration was retarded from implants lying in the anterior chamber; this was most evident when grafts were placed in front of the iris and not in contact with the swollen vitreous body. Incorporation of 3H‐leucine in the neural retina and vitreous body was also investigated using autoradiography. No significant difference in labeling was seen between the control and lentectomized neural retina at all time intervals studied. However, increased labeling above that in the controls was observed over the vitreous body between 8 to 20 days after lentectomy. There was also an increase in the number of silver grains over the vitreous body with increasing time between injection of isotope and sacrifiec of the animal. These results provide evidence that vitreous body plays an important role in the process of lens regeneration, perhaps serving as a preferential pathway for transfer of the neural retinal factor to the dorsal iris.
Sperm maturation and the formation of sperm pairs in the epididymis of the opossum, Didelphis virginiana
Authors: Temple‐Smith P. D. , Bedford J. M.
Published: June 2005

Didelphis spermatozoa released from different levels of the epididymis exhibit a series of changes that reflect events involved in the process of their maturation. Their progression through the duct is accompanied by a rotation of the sperm head on the axis of the tail, by an eccentric movement of the cytoplasmic droplet to the anterior region of the midpiece from where it is discarded, by appearance in the posterior midpiece of regular submembranous electron‐dense ridges, and by visible condensation of the mitochondrial cristae and matrix. The latter seems to correlate generally with onset of the ability for progressive motility acquired by most spermatozoa as they reach the lower corpus epididymidis. This phase is associated also with the beginnings of the pairing by the acrosomal surface that characterizes mature spermatozoa of New World marsupials. Use of lectins and cationized ferric colloid as affinity markers served to reveal changes occurring also in the character of the sperm head and tail surface prior to pairing.

This investigation strengthens the idea gained from previous study of an Australian marsupial, Trichosurus, that the complexity of sperm maturation in the epididymis of Metatheria is broadly comparable to that observed in most eutherian mammals.
The environmental control of hatching in Fundulus heteroclitus
Authors: Dimichele Leonard , Taylor Malcolm H.
Published: June 2005

Salinity, pH, dissolved oxygen, hydration, and temperature were examined as possible environmental cues that might intiate hatching in Fundulus heterolitus. Incubation in or transfer to water adjusted to ranges of salinity, pH, and temperature within the physiological range of the species had no direct effect on hatching. Eggs incubated in water with dissolved oxygen concentrations greater than 6 ml O2/L or solutions of Carbowax PEG 4000 producing an osomotic flux of water out of the eggs delayed hatching indefinitely. Incubation of eggs in air delayed hatching, regardless of the pO2. Eggs delayed for periods of up to 1 mo by incubation in air or in highly oxygenated water hatched normally when placed in water of 4 ml O2/L or less. Additionally, eggs that were partially dehydrated by incubation in air did not hatch when placed in a pressurized container of mineral oil. These results indicate that both water and low dissolved oxygen concentration are necessary for hatching to occur. Both of these conditions are likely to exist in the field when stranded eggs are immersed in water.
Diurnal changes in mouse mammary gland DNA synthesis
Authors: Borst David W. , Mahoney William B.
Published: June 2005

DNA synthesis was studied in mammary tissue from 13‐ and 15‐day pregnant Balb/c mice at different times during the day. Tissue was labeled with 3H‐thymidine (3H‐TdR) using both in vivo and in vitro techniques. The labeling index of mammary epithelial cells was determined by autoradiography. Incorporation of 3H‐TdR into TCA‐precipitable material after in vitro labeling was also measured. The labeling index of mammary alveolar cells is 2.5 times higher in tissue from animals studied at midnight when compared to tissue from animals studied at noon; ductal epithelial cells do not show any variation in labeling index at these time periods. Precursor incorporation into TCA‐precipitable material is also increased at midnight when compared to values at noon. Tissue from animals at 6 A. M. and 6 P. M. show intermediate levels of 3H‐TdR incorporation when measured by both of these methods. Diurnal variations in DNA synthesis in mammary tissue may reflect daily changes in either serum levels of those hormones directly stimulating this process or fluctuations in tissue sensitivity to these hormones, and might provide a means of analyzing the regulation of mammary epithelial cell proliferation during pregnancy.
The effects of α‐amanitin and cordycepin on vitellogenin synthesis by mosquito fat body
Authors: Kaczor W. J. , Hagedorn H. H.
Published: June 2005

Vitellogenin synthesis by mosquito (Aedes aegypti) fat body is stimulated by incubation with ecdysterone. α‐amanitin and cordycepin prevent the response to ecdysterone. These results support the hypothesis that ecdysterone regulates vitellogenin synthesis at the transcriptional level.
Analysis of yolk syncytium behavior in Salmo and Catostomus
Authors: Long Wilbur L.
Published: June 2005

The formation and early behavior of the yolk syncytial layer (YSL) of selected representatives of the teleost orders Clupeiformes and Cypriniformes are described, contrasted, and correlated with normal embryonic staging sequences. Movements of the cytoplasmic syncytium in Catostomus commersoni have been mapped by implantation of chalk particles and correlated with the morphogenetic movements of the blastodisc. The chalk particle experiments show for the first time that YSL cytoplasm which reaches the yolk plug during epiboly is not a part of the syncytium when gastrulation begins. Furthermore, there is a distinct convergence of YSL cytoplasm toward the dorsal midline during epiboly which mimics the motion of the cells at this time.
Intra‐allantoic implantation: An alternative to the classical chorioallantoic membrane grafting technique
Authors: Krukowski Marilyn , Iler H. Darrell , Kahn Arnold J.
Published: June 2005

A grafting method is described wherein donor tissue is partially inserted into a small slit cut into the proximal portion of the allantoic membrance of chick embryos aged 3.5–5.5 days. Cartilaginous bone rudiments handled in this manner readily vascularize, grow significantly, and begin osteogenesis within a 3‐day incubation period. Compared to traditional chorioallantoic membrane grafting, usually done with hosts aged 9–12 days, the proposed intra‐allantoic technique (1) greatly increases the period in which grafted materials are in residence (potentially up to 15 days) and (2) permits assessment of the host response of relatively young embryos.
Cytogeographical studies of the cell surface in Paramecium caudatum
Authors: Watanabe Tsuyoshi
Published: June 2005

In paramecium caudatum, distribution of two kinds of cortical units, i.e., one‐cilium units and two‐cilium units, was compared to the area of deciliation during sexual reproduction. Two‐cilium units, which were confirmed by the presence of 2 ciliary stubs after total chemical deciliation, are distributed on the anterior‐left (cell's left) field and circumoral field of the ventral surface. Near the anterior tip region, two‐cilium units were observed on both sides of the suture line. In contrast with this, the postero‐ventral half of the cell and the dorsal surface are composed exclusively of one‐cilium units. When the area of local deciliation during sexual reproduction was compared with the area containing two‐cilium units, no correlation was observed except at the anterior tip region.
Reversible stage‐specific embryonic inhibition mediated by the presence of adults in the annual fishNothobranchius guentheri
Authors: Inglima Kenneth , Perlmutter Alfred , Markofsky Jules
Published: June 2005

Nothobranchius guentheri, an annual fish from East Africa, is found in temporary ponds, pools, and streams that dry seasonally. The populations survive the dry season in the form of thickly chorionated embryos encased in the muddy substrate. WhenN. guentheriadults are allowed to spawn in the laboratory at 24.0 ± 1°C and the fertilized eggs are collected shortly afterwards, formation of the embryonic axis normally occurs within 5 to 11 days. However, examination of embryo populations obtained from unaerated aquaria after uninterrupted spawning periods of up to 2 or 3 months revealed only rare instances of embryogenesis. The overwhelming majority of embryos proceeded no further than the dispersed cell phase (diapause I, stage 20). Spawning was found to be continuous throughout these prolonged periods and the possibility of adult predation was eliminated. While low PO2has been determined to be a factor contributing to the duration of diapause I, determinations of PO2, PCO2, pH, free ammonia and bacterial flora indicated that aquarium conditions could support embryogenesis. Only embryos at stages 20 and 32, both being stages of naturally occurring diapause, could be inhibited. The inhibitory effect was dependent on the adult density and was diminished with aeration. It is proposed that, in nature, the adult‐produced inhibitory factor may be useful in the conservation and augmentation of the embryonic reserve which is the mainstay of annual fish populations in tropical areas of alternating rainy and dry seasons.
Ultrastructural localization of gonadotropin and luteinizing hormone releasing hormone in the pituitary gland of a teleost fish (the platyfish)
Authors: Margolis‐Kazan Henrietta , Peute Jan , Schreibman Martin P. , Halpern Leslie R.
Published: June 2005

Immunoreactive luteinizing hormone releasing hormone (irLHRH) and immunoreactive gonadotropin (irGtH) are demonstrated in the pituitary gland of a teleost fish (Xiphophorus maculatus, the platyfish) at the ultrastructural level. Using an immunoperoxidase procedure, irGtH and irLHRH are specifically localized over the secretory granules of both gonadotropes and some cells of the pars intermedia (PI). All other pituitary cell types lack immunoreactive material. A concept of LHRH receptors on gonadotrope granules is discussed and a new function for a class of PI cells is suggested.
Hormone‐cytoplasmic interactions controlling sperm nuclear decondensation and male pronuclear development in starfish oocytes
Authors: Schuetz Allen W. , Longo Frank J.
Published: June 2005

Numerous highly condensed sperm nuclei were present in the cytoplasm of starfish oocytes fertilized at the germinal vesicle stage. Decondensation of sperm nuclei and formation of male pronuclei and asters followed treatment of such fertilized oocytes with meiosis‐inducing hormone 1‐methyladenine (1‐MA). Transformation of sperm nuclei was asynchronous, occurred only after germinal vesicle breakdown (GVBD), and was associated with characteristic clearing of the adjacent cytoplasmic organelles. GVBD and sperm nuclear changes were both inhibited when dinitrophenol was added to previously fertilized GV‐intact oocytes. Results demonstrate that polyspermy occurs readily in immature oocytes and that 1‐MA plays a key role in establishing the block to polyspermy. Furthermore, the factors necessary for sperm nuclear decondensation and pronuclear development do not exist in the cytoplasm of immature oocytes but arise following dispersal of germinal vesicle contents into the cytoplasm. Thus, absence of embryonic development in fertilized GV‐intact oocytes is linked to a lack of both oocyte and sperm nuclear differentiation rather than to a lack of sperm entry into the cytoplasm.