bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoperiodic control of antler cycles in deer. V. Reversed seasons
Authors: Goss Richard J.
Published: June 2005

Newborn and weanling fawns were held under reversed annual light cycles to learn if the subsequent replacement of their antlers would coincide with the anniversary of their births, as occurs in nature, or adapt to the artificial seasons of increasing day lengths even when these fall at the “wrong” time of year. The first sets of antlers developed at approximately the normal age when the deer were yearlings. These antlers, however, were shed and replaced half a year earlier than would otherwise haveoccurred under natural environmental conditions. It is concluded that the onset of renewed antler growth is not a response to every other time the photoperiod increases or decreases, but is triggered by lengthening days, irrespective of the age of the deer.
Studies on oocyte maturation of the medaka, Oryzias latipes. VIII. Role of follicular constituents in gonadotropin‐ and steroid‐induced maturation of oocytes in vitro
Authors: Iwamatsu Takashi
Published: June 2005

Participation of the follicular constituents in gonadotropin‐ and steroid‐induced maturation of Oryzias latipes oocytes was examined in vitro by removing these constituents and coculturing them with the denuded oocytes. Removal of all follicular constituents prevented gonadotropin‐induced maturation of oocytes, but the removal of the thecal cells and the basal lamina from the follicle did not prevent maturation. Moreover, the denuded oocytes did mature in the presence of gonadotropin when cocultured with granulosa cells previously separated from large preovulatory follicles or with postovulatory follicles. However, the denuded oocytes did not respond to gonadotropin by maturing when cocultured with either thecal cells and basal lamina of the, premature follicles or the granulosa cells of small follicles 22–24 hr before ovulation. These results indicate that the presence of the granulosa cells of large pre‐ and postovulatory follicles is important for gonadotropin‐induced oocyte maturation. The denuded oocytes, which were incapable of responding to gonadotropin, were stimulated by various steroids to undergo meiotic maturation. The concentrations of steroids effective in inducing maturation were lower for the denuded oocytes than for the oocytes within intact follicles or enveloped by granulosa cells alone.

The present results suggest that the gonadotropin‐stimulated granulosa cells of both pre‐ and postovulatory follicles play a major role in inducing oocyte maturation through secretion of steroids in the circadian ovulatory cycle of Oryzias latipes.
Ribonucleosides bound to the major yolk components in eggs of the insects Euscelis and Smittia
Authors: Schmidt Otto , Jäckle Herbert
Published: June 2005

The uptake of radioactive RNA precursors into growing oocytes of insect ovaries was studied. In addition to incorporation of radioactivity into RNA, labelled nucleosides were also observed in the egg. Some of this radioactivity is bound covalently to yolk glycoproteins.
Insulin levels in the serum of intact and regenerating adult newts (Notophthalmus viridescens)
Authors: Liversage Richard A. , Banks Brian J.
Published: June 2005

Radioimmunoassay (RIA) procedures were used to determine whether or not insulin is present in the adult newt. The results show that measurable amounts of the hormone are present in samples ofpooled, fresh serum taken by cardiac puncture methods. We also found that there are no significant changes in the level of insulin in regenerating newts compared with intact animals.
Melatonin inhibition of vasopressin‐stimulated water transport in the toad urinary bladder
Authors: Haswell M. Stephen , Gern William A. , Ralph Charles L.
Published: June 2005

Because melatonin mimics the effects of microtubular disruptive agents (e.g., colchicine) in various cellular systems, we have examined its effect on water transport in the toad urinary bladder. Microtubules are essential to vasopressin‐stimulated water transport in this tissue and are labile to colchicine (Kachadorian et al., '79). In unstimulated urinary bladders, melatonin is without effect; however, in the presence of 20 μ/ml of vasopressin, 4 × 10−6M melatonin significantly reduced the stimulation of water transport in this preparation. The inhibition of water transport by melatonin is comparable to that effected by colchicine. The possibility that melatonin may modulate microtubular functions is discussed.
Histological structure of epithelial hydra and evidence for the complete absence of interstitial and nerve cells
Authors: Wanek Nancy , Marcum Beverly A. , Campbell Richard D.
Published: June 2005

Hydra were treated with colchicine, resulting in the elimination of interstitial, nerve, and stinging cells. These animals were cloned for several months and then examined histologically to determine: (1) the extent of cell depletion, and (2) the effect of this depletion on tissue structure and epithelial cell morphology. Thirteen of these hydra were serially sectioned for light microscopy and every cell was identified. All of the animals were composed solely of epithelial cells. No cells of the interstitial cell lineage, which includes interstitial cells, nerve cells, nematoblasts, and gametes, were found. Using experimental hydra with low numbers of interstitial and nerve cells, we verified that these cell types, when present, are readily identifiable in histological sections. Thus, we conclude that the cloned hydra are completely free of all cells except epithelial cells, and hence are defined as epithelial hydra. The histological organization of epithelial cells is normal in these animals. In each body region (hypostome, tentacles, gastricregion, peduncle, and basal disc) the organization of tissue and epithelial cell structure is normal. Therefore, epithelial cells are capable of autonomous region‐specific differentiations, and tissue architecture can arise independently of the interstitial cell lineage.
Limiting conditions for conjugation in Tetrahymena: Cellular development and factor active in conjugation
Authors: Wolfe Jason , Meal Katharine J. , Soiffer Robert
Published: June 2005

Conjugation in Tetrahymena thermophila is a three component system requiring starved cells of two complementary mating types and an extracellular macromolecular factor active in conjugation (FAC). Because the rate of cell pairing is related to the concentration of FAC in the extracellular medium, an assay for FAC was developed using standard test cells. The rate of release of FAC into the medium was measured in cells transferred from growth medium. It was found that a) FAC production is rapid, being detectable within 15 min after shift down; b) within 1 hr, sufficient FAC is released by the cells to support near maximal pairing activity among test cells; and c) cycloheximide completely blocks release of FAC. It was further demonstrated that addition of high‐titer FAC to freshly shifted down cells did not shorten the delay period before conjugation. Therefore, the starvation period is a time during which a) FAC is released into the medium, and b) cells develop receptivity to mating interactions, with the latter being rate‐limiting for conjugation. FAC is produced by sexually immature cells, by cells in growth medium, and by cells starving in high ionic strength buffer, but not by nonmating amicronucleate cells of T. pyriformis. Cell interactions during mating are modulated by FAC, but only among developmentally receptive cells.
Surgical removal of the olfactory bulbs increases sensitivity of the reproductive system of female rats to the inhibitory effects of late afternoon melatonin injections
Authors: Reiter Russel J. , Petterborg Larry J. , Trakulrungsi Chatchai , Trakulrungsi Wantanee K.
Published: June 2005

In rats, anosmia induced by olfactory bulbectomy sensitizes the neuroendocrine‐reproductive axis to the inhibitory effects of the pineal gland. Thus, combined blinding (which stimulates pineal antigonadotrophic activity) and anosmia cause a marked delay in the sexual maturation of female rats. The present study tested whether anosmia would also sensitize the neuroendocrine axis to the reproductive inhibitory effects of melatonin. In the present study, young female rats were rendered anosmic and maintained under light:dark cycles of 14:10; they were given melatonin injections daily (25 μg) at either 0900 hr (AM‐melatonin) or at 1800 hr (PM‐melatonin)—i.e., either 3 or 12 hr after lights on, respectively. The melatonin injections were begun when the rats were 23 days of age and were continued for 35 days. By comparison with AM‐melatonin, PM‐melatonin injections were considerably more effective in inhibiting bodily growth as well as the weights of the anterior pituitary, ovaries, and uterus of anosmic rats. Similarly, the changes in pituitary and plasma LH and PRL levels were more obvious in the PM‐treated anosmic rats than in those given melatonin in the morning. Thus, anosmia does increase the sensitivity of the neuroendocrine‐reproductive axis to melatonin, provided the indoleamine is administered late in the light phase of the light:dark cycle. Anosmia by itself had no influence on the daytime levels of radioimmunoassayable melatonin within the pineal gland, whereas in blinded control rats, melatonin levels were markedly augmented.
The transport of L‐alanine by the integument of the marine polychaete, Glycera dibranchiata
Authors: Stevens Bruce R. , Preston Robert L.
Published: June 2005

The unidirectional influx of14C‐L‐alanine into the external integument surface of Glycera dibranchiata was measured in the presence and absence of sodium using lucite influx chambers which permitted brief exposures of only the external surface of the body wall to isotope. The influx of alanine was the sum of a mediated component obligatorily dependent on sodium in the external medium, and a nonsaturable sodium‐independent diffusion component. The mediated component was inhibitable by other amino acids, lacked transconcentration effects, and had a Q10 of 9.64 near the acclimation temperature of 12°C. The diffusion component was not competitively inhibitable and had a Q10 of 0.99 at 12°C. The saturable component had a Kt = 8.63 × 10−5 M and Jmax = 1.38 × 10−7 mol/hr · cm2. The Kt falls within the physiological range of free amino acid concentrations to which the worm would be exposed in its habitat.
The effect of sodium on the kinetics of L‐alanine influx by the integument of the marine polychaete, Glycera dibranchiata
Authors: Stevens Bruce R. , Preston Robert L.
Published: June 2005

The kinetics of sodium‐dependent L‐(U‐14C)alanine influx into the integument of Glycera dibranchiata were studied in vitro utilizing lucite influx chambers. Glycera integument accumulated alanine via two distinct sodiumcoupled carrier mediated systems which are described by similar kinetic equations. The coupling coefficient determined by graphical analysis was equal to 3 for each influx system. Both systems share a common Kt = 8.6 × 10−5 M alanine which was not affected by sodium concentration. However, each system possessed dissimilar maximal influx values that were sensitive to sodium concentration. A model is presented describing the molecular events of sodium‐coupled alanine transport by the integumentary epithelial cell membrane of Glycera.
Sodium‐dependent steady state L‐alanine accumulation by the body wall of Glycera dibranchiata
Authors: Stevens Bruce R. , Preston Robert L.
Published: June 2005

The time course of alanine accumulation in vitro by body wall of the marine polychaete, Glycera dibranchiata, was studied in the presence and absence of sodium and metabolic inhibitors. Utilizing acute exposure‐retention techniques, the body wall was found to accumulate alanine against a 343:1 (tissue/sea water) concentration gradient at steady state when exposed to an amino acid concentration approximately that of its natural habitat (8.6 × 10−5 M). In the absence of sodium, or in the presence of the metabolic inhibitors 2,4‐dinitrophenol, sodium azide, and ouabain, the steady state alanine gradient is equal to unity. Accumulated alanine probaby resides intracellularly in the body wall, since the apparent extracellular space in body wall accounts for only 6% of the total tissue water. The 343:1 alanine gradient generated by the body wall is thermodynamically plausible in light of the proposed model of alanine influx in body wall epithelial membrane (Stevens and Preston, '80b). The energy available for such influx and accumulation can be derived directly from the sodium chemical gradient plus the membrane electrical potential or potassium gradient.
Arginine vasotocin‐induced in vitro oviductal contractions in Anolis carolinensis: Effect of steroid hormone pretreatment in vivo
Authors: Guillette Louis J. , Jones Richard E.
Published: June 2005

Ovariectomized female Anolis carolinensis were treated for 14 days with one of the following regimens: (1) estradiol (1 μg/0.05 ml saline/day), (2) progesterone (10 μg/0.05 ml saline/day), or saline (0.05 ml/day). Oviducts then were removed surgically and placed in a bath containing Munsick's solution, to which was added either arginine vasotocin (30 ng/ml) or saline. Although saline produced no effects, AVT‐treated oviducts exhibited rhythmic contractions regardless of pretreatment regimen. Five parameters of the contractions measured were: (1) duration, (2) amplitude, (3) Strength (duration × amplitude), (4) frequency, and (5) rest. Each parameter then was analyzed using a 2 × 3 × 8 mixed, repeated measure design and analysis. Pretreatment with estradiol and progesterone significantly affected contraction strength, amplitude, and duration. Progesterone pretreatment produced oviductal contractions significantly stronger than saline pretreatment (p < 0. 001), whereas estradiol pretreatment produced significantly weaker contractions that saline pretreatment (p < 0.001). These findings are in contrast to those previously recorded for mammals and other reptiles in which estrogens support and progesterone inhibits uterine contractions. These data may suggest a unique adaptation of hormonal control of oviductal contraction in A. carolinensis to the alteration of oviposition during this lizard's reproductive cycle.
Sperm head decondensation by a high molecular weight fraction of sea urchin egg homogenate
Authors: Eng Ludeman A. , Metz Charles B.
Published: June 2005

Sperm nucleus decondensing activity (NDA) of eggs has been investigated using the gametes of the sea urchin, Lytechinus variegatus. To assay for NDA, isolated sperm heads were exposed to homogenate from mature unfertilized ova and then examined with phase‐contrast optics. NDA is retained by dialysis and requires Ca++ at the time of homogenization as well as at the time of assay. Other divalent cations (Mg++, Sr++, Ba++, Mn++) can substitute for Ca++ but are much less effective. NDA is stable to cold (−20°C, −76°C) but not to heat (56°C). The pH activity optimum is in the range 7–9. NDA is present in the supernatant after centrifugation at 150,000 g for 105 minutes. It elutes shortly following the void volume on a Sephacryl S‐200 column, with an approximate M.W. of 100,000 daltons.
Pattern regulation of mesoderm in transplanted and supernumerary limbs of the cockroach. II. Time course of muscle dedifferentiation
Authors: Steinbach Paul A.
Published: June 2005

The extent and time course of muscle dedifferentiation was followed histologically in transplanted mesothoracic limbs of the cockroach Periplaneta americana. The limbs were grafted to contralateral leg sockets and were oriented such that the anterior‐posterior axis of the graft was reversed relative to that of the socket. The muscles in such a graft dedifferentiate before the first postoperative molt. Muscle dedifferentiation is characterized by the loss of muscle fibers and the appearance of mononuclear cells in the graft. Dedifferentiation begins proximally near the host/graft junction and progressively spreads to distal levels until the only remnants of the original muscle organization are aggregates of mononuclear cells around distal apodemes. Muscles in the thorax which were damaged. During transplantation also de differentiate before the first postoperative molt. Redifferentiation of identifiable muscle can begin as early as the second intermolt period. The dedifferentiation of transplanted mesoderm in not due to the axis reversal, since the muscles in a graft without axis reversal dedifferentiate to the same extent as in grafts with reversed transverse axes. The results are interpreted as indicating that developmental information from nonmuscular tissues in the limb is required for reformation of identifiable muscles.
Methylamine osmoregulatory solutes of elasmobranch fishes counteract urea inhibition of enzymes
Authors: Yancey Paul H. , Somero George N.
Published: June 2005

The intracellular fluids of marine elasmobranchs contain a set of methylamine compounds (trimethylamine oxide, betaine, and sarcosine) which are able to counteract the perturbing effects of urea on enzyme function (apparent Michaelis constant (Km) and maximal velocity). The counteracting effects of the methylamine compounds and urea are maximal at a 2:1 ratio [urea]:[methylamines]. This is the same concentration ratio for these osmolytes found in the cells of marine elasmobranchs, holocephalans, and the coelacanth.

The counteracting effects of the methylamine solutes and urea are observed with enzymes from non‐elasmobranchs as well as elasmobranchs, indicating that the enzymes of elasmobranchs are not specially adapted to function in the presence of urea or the methylamine osmolytes. Rather, the effects of urea and the methylamines on enzymes probably reflect fundamental protein‐solute interactions.

The urea tolerance conferred by the methylamine solutes may have played an important role in elasmobranch evolution. The relief from urea perturbation afforded by these methylamines may have precluded the requirement for widespread modifications in the sequences of elasmobranch proteins to allow these proteins to function in the presence of perturbing urea concentrations.
Pineal involvement in the control of behavioral thermoregulation of the white sucker, Catostomus commersoni
Authors: Kavaliers Martin , Ralph Charles L.
Published: June 2005

White suckers select a higher body temperature at night and a lower temperature during daytime. Removal of the pineal organ eliminated their diel rhythm of behavioral thermoregulation. After pinealectomy fish failed to select a lower daytime temperature. These results suggest that the pineal organ is involved in the control of behavioral thermoregulation of this teleost fish.
Pituitary stimulation of parathyroid hormone secretion: Evidence in cattle for a parathyroid stimulating hormone
Authors: Latman Neal S.
Published: June 2005

A number of previous investigations have indicated that the pituitary may directly stimulate of secretion of parathyroid hormone. Others have disagreed. With the recent development of an in vitro bovine parathyroid perfusion system, the direct effect of suspected secretagogues can be assessed on a dynamic, ongoing basis.

A partially purified pituitary extract (preparation A) was injected into calves. The plasma calcium increased an average of 1.1 mg/100 ml plasma. No increase of immunoreactive parathyroid hormone (iPTH) was detected, however, in the peripheral plasma prior to the increase in plasma calcium concentration. Since the peripheral plasma iPTH concentration has been shown to be relatively insensitive to changes in the secretion rate, the inability to detect a change in the iPTH concentration does not preclude a direct stimulating effect of the pituitary on the parathyroid.

When preparation A was tested on in vitro perfused bovine parathyroid glands, a 30% average increase in secretion of c‐iPTH (carboxy terminus) and a 56% average increase in secretion of n‐iPTH (amino terminus) was observed under normocalcemic conditions. Under conditions of hypercalcemia, there was an average increase in the c‐iPTH secretion rate of 60% and an average n‐iPTH secretion rate increase of 88%. A failure of TSH, LH, GH, ADH, oxytocin, and prolactin to stimulate iPTH was observed. Previous reports have eliminated ACTH, MSH, and lipotropin as possible parathyroid secretagogues.

The concept of a parathyroid stimulating hormone (PTSH) located in the pituitary that can directly stimulate the parathyroid gland to secrete parathyroid hormone is consistent with the results of this investigation.
The direction of evolution in the Drosophila melanogaster species subgroup based on functional analysis of the crystal cells
Authors: Rizki T. M. , Rizki Rose M.
Published: June 2005

The crystal cells in the hemolymph of Drosophila melanogaster contain paracrystalline inclusions and phenol oxidase. Melanization of this type of blood cell can be induced by treatment of larvae with hot water. By using this functional criterion to establish cell homology we compared the shape of the inclusions in the crystal cells of the D. melanogaster species subgroup and a number of distantly related species of Drosophila. The crystal cell inclusions in four of the sibling species (simulans, erecta, mauritiana, yakuba) are the same as those found in D. melanogaster. In the fifth species, D. teissieri, the crystal cell inclusions resemble those found in the hemocytes of the other larval drosophilids that were examined rather than those of D. melanogaster. On the basis of these observations and the phylogenetic relationships deduced from analysis of chromosomal inversions by Lemeunier and Ashburner ('76), we propose that D. teissieri is closer to the ancestral form or is the ancestral species of the melanogaster species subgroup of Drosophila. This is the first instance in which a hemocyte type has been used to determine the direction of evolution within a subgroup of insect species.
Glycerol permeabilities of fertilized and unfertilized mouse ova
Authors: Jackowski Suzanne , Leibo S. P. , Mazur Peter
Published: June 2005

The coefficients of permeability to glycerol, Pglyc, and their temperature‐dependence were determined from volume changes of fertilized and unfertilized mouse ova under hyperosmotic conditions. Fertilization caused a significant increase in the value of Pglyc. Unfertilized ova exhibited Pglyc values of 1 × 10−5, 2 × 10−6, and 5 × 10−7 cm/min at ∼20°C, ∼12°C, and ∼3°C, respectively. Fertilized ova exhibited Pglyc values of 3.4 × 10−5, 1.3 × 10−5, and 4.7 × 10−6 cm/min at ∼20°C, ∼12°C, and ∼3°C, respectively. The activation energy of glycerol permeation into fertilized and unfertilized ova was calculated to be 18.7 and 28.4 kcal/mol, respectively. Fertilization caused a rather dramatic increase in glycerol permeability, the major extent of which occurred within about 3 hours after fertilization. Pglyc was also measured at ∼20°C by isotope uptake. Glycerol uptake calculated indirectly from the volume changes of the ova agreed well with that measured directly by labeled glycerol uptake. It was also found that the zona pellucida of fertilized and unfertilized ova did not detectably impede the permeation by glycerol.
Further characterization of female sterile (1) 1304 mutant of Drosophila melanogaster
Authors: Mulligan Pamela Khipple , Rasch Ellen M.
Published: June 2005

The Drosophila melanogastor mutant fs(1) 1304 (1‐19 ± 2) has been characterized using various experimental approaches. The mutant ap4 (2‐55.2), used as a control in some of the experiments reported in this paper, has also been examined more carefully. Electrophoresis of ovarian extracts from the mutants on polyacrylamide gels yield results suggesting that vitellogenesis is completely inhibited in ap4/ap4 females, while it proceeds at an abnormally slow rate in fs/fs females. Both mutants accumulate hemolymph proteins in amounts in excess of those found in the hemolymph of wild type females, suggesting that uptake of proteins from the hemolymph is affected by both the mutant genes. Qualitative differences in the banding patterns obtained from the hemolymph of wild type and ap4 female suggest that homozygous ap4 females may also be defective in the synthesis or processing of yolk proteins. Three of the protein bands observed in our electropherograms are suspected to represent yolk proteins, and an additional band is thought to represent an aggregate of the three yolk proteins.

Neither juvenile hormone nor ecdysone treatment enhance vitellogenesis in fs(1)1304, although ap4 females produce yolky oocytes after JH treatment, in agreement with previously reported results. Ovarian transplantation studies suggest that fs(1)1304 behaves autonomously. Previous studies have shown that ap4 females behave non‐autonomously.
Cuticular lipid biosynthesis in the scorpion, Paruroctonus mesaensis
Authors: Hadley Neil F. , Hall Richard L.
Published: June 2005

The synthesis of cuticular and hemolymph lipids in the scorpion Paruroctonus mesaensis, was examined using radiolabeled acetate and palmitic acid. Incorporation of 1‐14C‐acetate into cuticular lipids was very low (0.03–0.13% of injected label), with the hydrocarbons exhibiting only trace (CPM's not significantly higher than background) radioactivity after 24 hours. Cuticular alcohols had the highest incorporation (ca. 80%) followed by free fatty acids and triglycerides. Hemolymph lipids also showed poor incorporation of labeled acetate (0.01%) and little activity in the hydrocarbon fraction. Incorporation of 1‐14C‐palmitic acid into cuticular lipids (0.86–1.21%) and hemolymph lipids (0.62–1.00%) was slightly higher, but still well below incorporation values observed for insects. The majority of the label appeared in the free fatty acids; hydrocarbons continued to show only trace radioactivity. Except for differences in the relative amounts of specific components, cuticular and hemolymph hydrocarbons were similar in composition. These results suggest that hydrocarbon biosynthesis in adult scorpions is very low during the intermoult period or that other compounds are preferred precursors.
Periodic spawning of three types of the ascidian, Halocynthia roretzi (Drasche), under continuous light conditions
Authors: Numakunai Takaharu , Hoshino Zen‐Ichiro
Published: June 2005

We observed the spawning behavior of three types of H. roretzi kept under continuous light conditions for a 2 week period. Three different spawning behaviors were observed. Type A spawned both under continuous light and continuous darkness. Type B spawned under continuous light and Type C under continuous dakness. All these type spawned twice a day. In contrast, animals under the natural light cycle spawn once a day. We propose that there are at least two periodic factors that define their spawning times. Spawning seasons were prolonged or advanced several months by keeping animals in cold sea water or in warm sea water. Their spawning times remained basically unchanged, although to some extent (depending upon the sea water temperature) they changed.
Effects of divalent cations on amino acid and divalent cation fluxes in gills of the bivalve mollusc, Mytilus californianus
Authors: Swinehart James H. , Crowe John H. , Giannini Albert P. , Rosenbaum David A.
Published: June 2005

Effects of the deletion of Ca++, Mg++, or Ca++ and Mg++ on the leakage of primary amines, Ca++, and Mg++ from gills of Mytilus californianus were studied. In the absence of Ca++ the gills leak primary amines and Ca++ for about 30 minutes, after which the primary amines are reabsorbed. In the absence of Mg++ the gills leak primary amines, with no net reabsorption for at least 90 minutes, and show rapid leakage of Mg++. In the absence of both Ca++ and Mg++ amino acid leakage is initially less than in the absence of only one of the cations. Measurements of the kinetics of leakages of Ca++ and Mg++ are consistent with the hypothesis that both ions are associated with the cell surface, but the affinity of Ca++ for the cell surface is greater than that of Mg++.

In the absence of Mg++, the influx of 14C‐glycine was depressed to about 1/3 that seen in controls, while deletion of Ca++ had no effect on the rate of influx. Increasing the [Mg++] stepwise between 5 × 10−6 and 1 × 10−1 M results in a sigmoidal increase in the rate of influx of 14C‐glycine and a hyperbolic increase in the y‐intercept of influx curves.
Responses of the screening pigments in the compound eye of Neomysis integer (Crustacea: Mysidacea)
Authors: Hallberg E. , Andersson M. , Nilsson D.‐E.
Published: June 2005

The following responses of the screening pigment in the compound eyes of the mysid Neomysis integer(Leach) were studied using histological methods: viz. the light and dark adaptation, the reaction of the light‐adapted eyes towards different light intensities, and the pigment distribution during prolonged exposure to light and darkness. The light and dark adaptations of the screening pigments are characterized by a strong initial reaction, which is followed by a gradual approach to a more or less stable state. In the light adaptation of the proximal pigment, the initial distal movement is especially pronounced, followed by a phase during which the pigment moves proximally. The eye is light‐adapted in about 20 minutes. Dark adaptation, on the other hand, is a slower process requiring more than an hour. The position of the pigment in the light‐adapted eyes is influenced by the light intensity, as the limits of the pigment shield progress in increasing light intensities. In animals subjected to total darkness or continuous illumination, the variations of the pigment screen could not be correlated with cyclic diurnal migrations.
Characterization of the methylxanthine‐induced propagated wave phenomenon in striated muscle
Authors: Coleman Annette W. , Coleman John R.
Published: June 2005

Escalation is a propagated wave phenomenon readily observable in chick skeletal muscle fibers growing in culture. It occurs in fibers bathed in methylxanthines, halothane, or quinine, at concentrations associated with twitch potentiation. From the results of a variety of experiments, an explanation of the phenomenon is proposed. Cation requirements suggest that a wave may be initiated in conjunction with a spontaneous calcium influx or calcium spike; and drug concentration, temperature, and extracellular potassium effects support the theory that wave propagation occurs by calcium‐induced calcium release from the sarcoplasmic reticulum. The optical effect may then reflect osmotic changes associated with the transient calcium release. Escalation is not restricted to cultured muscle, nor to chick. At appropriate temperatures and in the presence of methylxanthines, escalation has been observed in chick, frog, and rat skeletal muscle. This suggests that it is a subthreshold event, related to contraction, capable of providing further insight into excitation‐contraction coupling. The superior visibility conditions accessibility to experimental manipulation make cultured chick skeletal muscle fibers suitable subjects for such study.
Dominant lethal induction by ethyl methanesulfonate in the male axolotl (Ambystoma mexicanum)
Authors: Armstrong John B. , Gillespie Laura L.
Published: June 2005

When male axolotls (Ambystoma mexicanum) were treated with ethyl methanesulfonate (EMS) and mated at regular intervals thereafter, the incidence of embryonic abnormalities among the F1 progeny increased until a time was reached when none survived to hatching. At 100 mg/1 EMS, this point was reached about 130 days after treatment. Thereafter, the frequency of abnormalities gradually decreased to control levels. At higher concentrations, abnormalities were seen in spawnings obtained sooner after treatment, and also at earlier developmental stages. The pattern is similar to that reported for the mouse, which has been attributed to differential sensitivity of the various germ cell stages to the mutagenic agent. The time course, however, is greatly extended in the axolotl. In future experiments we will be looking for gene mutations, primarily before and after the period of peak mortality.
Nuclear basic protein changes during spermiogenesis in the longnose skate and the spiny dogfish
Authors: Bols N. C. , Boliska S. A. , Rainville J. B. , Kasinsky H. E.
Published: June 2005

Nuclear shape and the organization of nuclei within the seminiferous follicles have been used to divide spermiogenesis in the longnose skate, Raja rhina, into eight stages and in the spiny dogfish, Squalus acanthias, into seven stages. Cytochemical techniques for basic proteins reveal that as spermatid nuclei begin to elongate they have the somatic histone complement, and as they complete elongation they contain a very arginine‐rich, TCA‐extractable complement, or the salmon sperm histone type. After the nuclei have developed their ultimate corkscrew shape the final transition takes place to a very arginine‐rich, TCA‐stable complement, or the mammalian sperm histone type. These nuclei were not rich in sulfhydryl groups, but they were extractable with sodium thioglycolate. In addition, a number of variables affecting TCA extraction and subsequent alkaline fast green staining are described.
Lens formation from cornea in the presence of the old lens in larval Xenopus laevis
Authors: Bosco Luigi , Filoni Sergio , Cioni Carla
Published: June 2005

Three different types of experiments were carried out to investigate the role of the lens in lens‐forming transformations of the outer cornea of Xenopus laevis tadpoles (at stage 51, as defined by Nieuwkoop and Faber, '56): 1) simple lentectomy; 2) incision of outer and inner cornea in the region opposite the dorsal iris without lens removal; and 3) incision of outer and inner cornea and perforation of dorsal iris without lens removal. The results indicate that the outer cornea of Xenopus laevis larvae has lens‐forming competence, even in the presence of the old lens, only when direct communication has been set up between the outer cornea and the environment of the vitreous chamber. These data indicate that the inhibition exerted by the lens on lens‐forming transformations of the outer cornea is mechanical in nature.
In vivo induction of ovarian development in decapitated Aedes atropalpus by physiological levels of 20‐hydroxyecdysone
Authors: Kelly Thomas J. , Fuchs Morton S.
Published: June 2005

The Bass Rock strain of the mosquito Aedes atropalpus is autogenous for the first gonadotropic cycle; i.e. adult females will undergo normal oocyte maturation without the benefit of a blood meal. Yolk deposition can be completely inhibited if these animals are decapitated within 6 hours or abdominally ligated within 8 hours of adult emergence. Injection of 4.8 ng of 20‐hydroxyecdysion into 12‐hour‐old adult females that had been decapitated soon after eclosion restored vitellogenesis in 100% of the treated insects. With this dosage of hormone 50% of the oocytes appeared mature 72 hours after injection. When the amount of hormone administered was increased to 4.8 × 103 ng all of the follicles in 100% of the animals contained yolk, but the average follicle length was 35% less than the vitellogenic follicles of either the non‐decapitated controls or the decapitated females that had received 4.8 ng of hormone.

Yolk deposition was not restored in isolated abdomens by 4.8 ng of 20‐hydroxyecdysone. When the dosage was increased to 5 × 103 ng, 100% of the abdomens injected had follicles with yolk, and almost all the follicles contained yolk, but the average follicular length was reduced by 42% compared to intact controls.

The vitellogenic activity induced by μg quantities of 20‐hydroxyecdysone in decapitated females or in isolated abdomens is no doubt nonphysiological. However the fact that a single injection of only 4.8 ng of 20‐hydroxyecdysone was capable of inducing in vivo vitellogenesis in decapitated females suggests that this hormone is normally required for this process to occur. Since isolated abdomens did not respond to this amount of 20‐hydroxyecdysone, the possibility that the presence of a thoracic factor, perhaps juvenile hormone, may also be necessary for normal ovarian development in A. atropalpus is discussed.
Ventilation and oxygen consumption in the Dungeness crab, Cancer magister
Authors: McDonald D. G. , Wood C. M. , McMahon B. R.
Published: June 2005

The respiratory system of the crab Cancer magister has been investigated in unrestrained specimens fitted with electrodes for monitoring heart rate, branchial pressure catheters for monitoring scaphognathite rate, a ventilation mask containing an electromagnetic flow probe for measuring instantaneous branchial water flow and water sampling catheters for determining gill oxygen extraction and oxygen consumption. In animals recently stressed by physical restraint and air exposure, heart rate, branchial water flow and oxygen consumption were elevated and both scaphognathites pumped continuously in a predominantly forward direction, whereas in well‐acclimated animals ventilation rate and oxygen consumption were low, gill oxygen extraction was elevated, unilateral ventilation predominated and both ventilatory pauses and periodic reversals of scaphognathite beating were common. Analysis of the relationship between branchial water flow and scaphognathite rate reveals that the scaphognathite operated at a constant stroke volume for forward pumping but not for reverse pumping. Furthermore, the stroke volume was significantly lower for the latter over the normal range of scaphognathite rates in this mode. Reverse pumping and ventilatory pauses are behaviors that often occurred in the apparent absence of extrinsic stimuli in this species, thus their possible roles in gas exchange have been analyzed and are discussed.
Ultrastructure of cell hybrids between mouse oocytes and blastomeres
Authors: Szöllösi D. , Balakier H. , Czolowska R. , Tarkowski A. K.
Published: June 2005

Cell hybrids were formed between mouse ovarian oocytes and blastomeres from 2‐, 4‐ and 16‐cell stage embryos. No centrioles were located at the spindle pole, no matter what the origin of the blastomere, but microtubule organizing centers (MTOCs) of varying size were regularly present. After fusion the arrangement of the two chromosome sets varied. In some cases the meiotic chromosomes formed metaphase plate I, while the chromosomes of the blastomere under‐went premature condensation and were either scattered on the spindle surface or among the spindle microtubules. In other cases the meiotic and mitotic chromosomes intermingled at random within a large cytoplasmic islet, while a true spindle did not form. None of the hybrids cleaved, although on occasion the first polar body was extruded. The two hemispheres composing the hybrid and originating from the oocyte and blastomere could be recognized due to the presence or absence of cortical granules in the cell cortex.
Supernumerary limb structures with regenerated posterior chick wing bud tissue
Authors: Iten Laurie E. , Murphy Douglas J.
Published: June 2005

When a large wedge of stage 21 posterior chick wing bud tissue was removed and the cut edges were pinned together, wings with a complete complement of skeletal elements developed in 91% of the cases. Twenty‐four hours after removing this wedge of posterior limb bud tissue, tissue had regenerated that was capable of causing the formation of supernumerary (extra) limb skeletal elements when transplanted to a site in the anterior half of a host wing bud. The extra structures formed were similar to those formed when a wedge of non‐regenerated, posterior edge, stage‐21 wing bud was transplanted to a more anterior position in a host wing bud. When a rectangular shaped portion of posterior edge stage‐21 wing buds was removed and the cut edges were not pinned together, five of 15 cases formed a wing with a complete set of skeletal elements and the rest were missing an ulna and/or digit IV or digits III and IV. Twenty‐four hours after removing this rectangle of posterior‐edge wing bud tissue, tissue had regenerated which, when transplanted to a more anterior position in a host wing bud, resulted in the formation of supernumerary skeletal elements. These results are contrary to those obtained by Fallon and Crosby ('75), who concluded that there was no regeneration of posterior wing bud tissue capable of causing the formation of supernumerary wing structures when transplanted to a more anterior position in a host wing bud.
Concanavalin A binding capacity of preimplation rat embryos
Authors: Wu Jung‐Tsung
Published: June 2005

The number of concanavalin A (Con A) binding sites was determined in Days 2–5 rat embryos (Day 1 = sperm‐positive) by Scatchard plot analysis. There were 127 ± 13 million sites on Day 2 (2‐cell), which were decreased slightly to 88 ± 9 million sites on Day 3 (2 ∼ 4‐cell), then increased to 200 ± 24 million sites on Day 5 morning (early blastocyst) and 175 ± 21 million sites on Day 5 evening (late, implanting blastocyst). However, the apparent association constant decreased steadily with development, from about 3 × 106 M−1 on Days 2 and 3 to 1.3 × 106 M−1 on Day 5 evening.

Thus, in comparison with the results of mouse embryos (Wu, '80), the number of Con A binding sites was not increased in the implanting rat blastocyst, as it was in the mouse, although there were comparable numbers of Con A binding sites up to the early blastocyst stage in both species. The data also suggest some changes in the sugar groups, and probably the surrounding groups, on the surface coat of the plasma membrane during the preimplantation stages of development.
Studies on the female sterile mutant rudimentary of Drosophila melanogaster. III. Cell death in rudimentary wing imaginal discs
Authors: Fausto‐Sterling Anne
Published: June 2005

Previous work on the effect of the locus rudimentary on wing morphogenesis showed that a disproportionate reduction in the number of cells in the posterior region of the wing accounted for the changes in wing shape. In the present study, I used both clonal analysis and direct histological observations to demonstrate that the deficiency in cell number in the adult wing resulted from cell death and that cell death can account for the changes in both the size and shape of r wings. Some discussion was devoted to the possible mechanisms by which an alteration in pyrimidine metabolism might lead to cell death.
The physiological control of reproduction in Microdeutopus gryllotalpa (Crustacea: Amphipoda). I. The effects of exogenous ecdysterone on the females' molt and behavioral cycles
Authors: Borowsky Betty
Published: June 2005

In most amphipod crustacean females, the molt is followed shortly by copulation, and this is followed shortly by ovulation. Thus, the ovarian, molt, and behavioral cycles are hypothesized to be coordinated by a master physiological control system. This study presents evidence that the behavioral cycle is tied to the molt cycle. Injections of females with the crustacean molting hormone, 20‐hydroxyecdysone or ecdysterone, hastened the onset of the molt and receptive sexual behavior. This suggests that the behavioral cycle is either tied directly to the level of ecdysterone or tied to some other physiological change associated with the molt that is stimulated by the hormone.
Metabolism of chitin precursors by crayfish tissues during chitin synthesis
Authors: Stevenson J. Ross , Hettick Bruce P.
Published: June 2005

In order to follow changes in chitin precursors during chitin synthesis in the crayfish, Orconectes sanborni, tissue extracts were analyzed with an anion exchange column before and after injection of 14C‐N‐acetylglucosamine. Glucose concentration was found to be much lower in the blood than in the other tissues. Therefore, any movement into the tissues must occur against a steep concentration gradient. In the epidermis, most of the metabolites of the chitin synthetic pathway were absent in early premolt stage D0, and they were at their highest concentration in late premolt stage D3, when chitin synthesis was underway. Apparently the synthesis of these chitin precursors is initiated after premolt state D0. In epidermis, midgut gland, and muscle, the chitin precursors found in highest concentration, N‐acetylglucosamine‐6‐phosphate and UDP‐N‐acetyl‐glucosamine, decreased in concentration between stage D3 and postmolt stage C1‐2, the stage when rate of chitin synthesis is highest. This suggests the early enzymes in the chitin synthetic pathway, but not the late enzymes, increase in activity in premolt, causing accumulation of these two compounds. Then the late enzymes increase in activity in postmolt, reducing the levels of accumulated precursors and raising the overall rate of chitin synthesis. Chitin precursors were found in midgut gland and muscle, but little incorporation of label into macromolecules was seen. This suggests the possibility that these tissues may synthesize chitin precursors for use in chitin synthesis by the epidermis. Some N‐acetyl‐glucosamine‐6‐phosphate was found in the blood, possibly en route from the tissues that synthesize it, such as midgut gland and muscle, to the epidermis, which uses it for chitin synthesis. Even late in premolt, the chitin of the old cuticle, soon to be shed, became labeled. Therefore, the cuticle may serve as a reserve food supply by its continual breakdown and resynthesis.
Variability of response of early Drosophila embryos to heat shock
Authors: Graziosi G. , Micali F. , Marzari R. , de Cristini F. , Savoini A.
Published: June 2005

Several embryonic stages (nuclear multiplication stage up to blastoderm) were incubated at 37°C. The 84,000 dalton heat‐shock protein was always present in the heat‐shocked embryos at all these stages. This protein was also found in nonheat‐shocked controls. Different amounts of two other heat‐shock proteins, the 70,000 and 68,000 daltons, were synthesized depending upon the embryonic stage. A massive synthesis of these two later proteins was observed in embryos which were able to recover from the heat‐shock.
Polar differences of delayed and implanting mouse blastocysts in binding of Alcian Blue and concanavalin A
Authors: Nilsson B. Ove , Naeslund G. , Curman B.
Published: June 2005

Mouse blastocysts in delay of implantation and after an 18‐hour activation for implantation by estrogen were recovered by flushing with glutaraldehyde containing Alcian Blue or by flushing with cold Dulbecco's PBS containing 0.1% sodium azide for further processing according to an Alcian Blue technique and a ConA‐latex technique, respectively.

Blastocysts in delay of implantation showed no or only faint staining with Alcian Blue, while blastocysts activated for 18 hours displayed a marked staining of the abembryonic pole. Binding of ConA‐latex spheres demonstrated a markedly higher density at the abembryonic end of both delayed and implanting blastocysts. It is concluded that, as demonstrated by the Alcian Blue technique, the abembryonic trophoblast, which is the first one to attach and invade at implantation, has changed the properties of the extracellular coat, probably in a way that favors increase of adhesiveness and invasiveness. The similarity in pattern of ConA binding of both delayed and implanting blastocysts, however, suggests that this property is related more to preimplantational differences in proliferative activity of the two poles than to implantatory changes.
Lactate increases the oxygen affinity of crab hemocyanin
Authors: Truchot J.‐P.
Published: June 2005

At concentrations between 0 and 15 mM, L‐lactate increases the oxygen affinity of the hemocyanin in hemolymph dialysates of the crabs Carcinus means and Cancer pagurus without changing the Bohr effect. A possible role of lactate and other anaerobic end products as cofactors regulating the oxygen transport function is suggested.