bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of a light pulse during the dark on photoperiodic regulation of the rate of thyroxine‐induced, spontaneous, and prolactin‐inhibited metamorphosis in Rana pipiens tadpoles
Authors: Wright Mary L. , Jorey Suzanne T. , Blanchard Linda S. , Basso Carolyn A. 
Published: June 2005

AbstractSince Rana pipiens tadpoles injected with thyroxine (T4) early in the dark develop more slowly than those injected in the light, we studied the effect of giving a light pulse of 1 hr early in the dark. Tadpoles injected under a 7.5‐W red light bulb in a darkened room with 0.2 μg T4 daily at 2200 hr went through metamorphosis faster on a 12L:3D:1L:8D cycle with a light pulse after injection than on a 12L:12D cycle without a light pulse, and even faster on a 12L:1.5D:1L:9.5D cycle with a light pulse before the injection. Thus a 1‐hr light pulse counteracted the metamorphic delay resulting from administration of T4 in the dark, and set in motion the conditions that resulted in a more rapid response to an injection of T4. However, a 1‐hr light pulse in the early dark had no effect on growth and development of older or younger untreated tadpoles or those constantly immersed in 30 μg/liter T4.Larvae on 21L:3D with T4 injection in the dark and on 12L:3D:1L:8D with T4 injection at 0700 hr just before the start of the main light phase progressed faster than 12L:3D:1L:8D with injection at 2200 hr in the dark before only a 1‐hr light pulse. Thus the length of the light phase immediately after T4 injection was significant. There was no difference on 12L:12D and 12L:3D:1L:8D cycles in the effectiveness of daily injections of 10 μg prolactin (PRL) in the early dark at 2200 hr in promoting tail growth or antagonizing tail resorption induced by T4 immersion. Under these conditions, PRL utilization did not appear to be inhibited by the light pulse.
Strain differences in early mouse embryo development in vitro: Role of the nucleus
Authors: Robl J. M. , Lohse‐Heideman J. K. , First N. L. 
Published: June 2005

AbstractMouse embryos of many strains are blocked in development at the two‐cell stage when placed in culture at the one‐cell stage. If, however, they are placed in culture at the two‐cell stage, they develop to blastocysts at a high rate. We investigated the transcriptional and translational systems in blocked embryos by assaying enzymatic activity of the protein product of an injected gene and found these systems to be functioning normally. The role of the nucleus was investigated by reciprocal nuclear transplants between blocked and nonblocked embryos. The results indicate that the source of the nucleus was of equal importance to that of the cytoplasm for the successful development of embryos cultured from the one‐cell stage. When cultured from the two‐cell stage, however, the nucleus was solely responsible for strain differences in culture rates.
S6 phosphorylation is regulated at multiple levels in Xenopus laevis oocytes
Authors: Wasserman William J. , Freedman Alan , Penna Mary Jo 
Published: June 2005

AbstractIt is known that the 40s ribosomal protein S6 undergoes a dramatic increase in its level of phosphorylation during Xenopus oocyte meiotic maturation in response to progesterone stimulation. During prophase arrest, the majority of S6 has 0 moles phosphate per mole protein; this increases to 4–5 moles phosphate per mole protein by the time of germinal vesicle breakdown (GVBD). Our in vitro and in vivo studies indicate that the accumulation of phosphate on S6 is the net result of a 4–5‐fold increase in S6 kinase activity and a 30–50% decrease in the rate of dephosphorylation and/or turnover of phosphate groups on S6 in maturing oocytes. In addition, the level of phosphorylation of S6 on 80s monosomes injected into non‐hormone‐stimulated oocytes was unexpectedly high. This indicates that the S6 kinase/phosphatase ratio in prophase arrested oocytes is higher than anticipated from previous studies. This observation implies that the majority of the oocyte ribosomes may be sequestered from any S6 kinase during meiotic prophase. Furthermore, these observations suggest that a portion of the increased accumulation of phosphate on S6 may be the result of increased accessibility of the ribosomes to S6 kinase during oocyte meiotic maturation.
Renal structural flexibility in response to environmental water stress in feral hogs
Authors: Zervanos Stam. M. , Naveh Sharon 
Published: June 2005

AbstractSeveral morphological characteristics of the kidney were studied to determine the degree of acclimatization that may occur in three groups of feral hogs raised under different environmental conditions. Two groups of hogs were living in the wild, while another was raised in captivity for three generations and was directly descended from one of the wild‐living groups. The two groups of wild hogs were living under two different types of water stress conditions. One group experienced periodic drought, and the other ate a high salt diet. The captive hogs were given food and water ad libitum. The captive‐raised hogs had significantly lower relative medullary thickness (RMT) and relative medullary area (RMA) values (RMT of 2.35; RMA of 0.35) than either group of hogs living in the wild (RMT of 2.70 and 2.69; RMA of 0.41 and 0.44). Since the feral hogs living in the wild were exposed to a higher degree of water stress than the captive‐raised hogs, it was concluded that the differences in observed kidney structure were due to acclimatization.
Multiple functions of carbonic anhydrase in the crustacean gill
Authors: Henry Raymond P. 
Published: June 2005

AbstractThe enzyme‐catalysed hydration of CO2 gas by carbonic anhydrase produces the ionic species H+ and HCO3−. The chemical species involved in the reaction scheme are further used in a variety of different physiological and biochemical processes, each of which at least potentially relies on carbonic anhydrase to keep those chemical species from being limiting. Two such processes, CO2 excretion and ion uptake, occur in the crustacean gill. On the surface it would appear that these processes are mutually exclusive in a single organ, as the former requires the net dehydration of HCO3−, and the latter requires the net hydration of CO2. That carbonic anhydrase can meet the requirements of both processes is due to its compartmentalization within different subcellular fractions of the gill tissue. Carbonic anhydrase associated with the basal‐lateral branchial membrane mobilizes hemolymph HCO3− to CO2 for excretion, while intracellular (cytoplasmic) carbonic anhydrase, through the catalysed hydration of CO2, provides H+ and HCO3− for use in Na+ and Cl− uptake.
Determinants of the larval molting pattern of the crustacean Balanus eburneus Gould (Cirripedia: Thoracica)
Authors: West Terry L. , Costlow John D. 
Published: June 2005

AbstractLarval development of the thoracican cirripede Balanus eburneus is invariant, consisting of six naupliar instars and a terminal nonfeeding cypris instar. In order to elucidate determinants of its fixed instar molting pattern we tested the following hypotheses: (1) the rate of morphogenesis is correlated with the rate of molting; (2) the timing of the morphogenetic molt to the cyprid is time (age) dependent; and (3) initiation of the molt to the cyprid is dependent upon the accumulation of a minimum amount of energy reserves. Naupliar food supply was manipulated in order to vary rates of molting and accumulation of energy reserves. Total oil cell volume per larva was used to nondestructively estimate energy reserve level.Compound eye development and thoracic appendage development during the six naupliar instar were confined to specific phases of the molt cycle. Suspension of the molt cycle resulted in suspension of morphological development. Initiation of the molt to the cyprid was neither time dependent nor a function of larval oil cell volume. However, the rate of passage through the molt cycle increased abruptly in larvae having an oil cell volume greater than 4–6 × 104 μm3. Nauplii entering the final phase of the molt cycle (D2–4) would attempt to complete development to the cyprid irrespective of their oil cell volume. Correlations between cypris oil cell volume and cypris metamorphic success implied that the naupliar oil cell volume “threshold” of 4–6 × 104 μ3 represented the amount of energy reserves needed to complete covert developmental events rendering the cyprid capable of successfully metamorphosing to the juvenile.These results suggest that molt cycle stage‐specific morphogenesis and growth (energy reserve accumulation) are important determinants of the fixed instar molting of B. eburneus larvae. Comparisons with studies of larval crustaceans which vary instar number indicate (1) greater independence between the processes of molting and morphogenesis among species with a variable instar molting pattern and also that (2) growth is an important determinant of each type of molting pattern.
Influence of thyroidal status on ovarian function in rainbow trout, Salmo gairdneri
Authors: Cyr Daniel G. , Eales J. G. 
Published: June 2005

AbstractFemale rainbow trout were rendered either hypothyroid by ipodate injection or hyperthyroid by immersion in a 3,5,3′‐triiodo‐L‐thyronine (T3) solution or by feeding T3‐supplemented pellets, and ovarian function was evaluated from the gonadosomatic index (gonad weight .102. body weight−1 = GSI), plasma 17β‐estradiol (E2) level, or the ability in vitro of ovarian pieces to release E2 in the presence of salmon gonadotropin (sGtH). Hypothyroidism for 7 or 22 days depressed GSI or in vitro ovarian E2 release. Modest hyperthyroidism for 7 or 22 days, which raised plasma T3 from 1.6–3.3 ng/ml (controls) to 4.1–7.7 ng/ml, significantly increased GSI and in vitro ovarian E2 release. However, at higher T3 levels (21–33 ng/ml) there was no increase in GSI and either no increase or a significant decrease in ovarian E2 release. None of these treatments altered the plasma E2 levels although T3 treatment significantly enhanced the effect of injected sGtH in elevating E2 level. It is concluded that T3 at physiologic levels enhances ovarian growth and GtH stimulation of E2 production, but when plasma T3 levels exceed those required to saturate putative T3 receptor sites, T3 tends to inhibit ovarian function.
Secretion of ecdysteroid by sheaths of testes of the gypsy moth, Lymantria dispar, and its regulation by testis ecdysiotropin
Authors: Loeb M. J. , Brandt E. P. , Woods C. W. , Bell R. A. 
Published: June 2005

AbstractTestes of the gypsy moth, Lymantria dispar, secrete ecdysteroid in vitro during the silk‐spinning pharate pupa stage and in mid to late adult development during the pupal stage. Low titers (3–6 pg/μl) of exogenous 20‐hydroxyecdysone are required to elicit endogenous ecdysteroid production. Testis ecdysiotropin (TE) was detected in acid methanolic extracts of brains of immobile pharate pupae and mid‐development pupae. It was possible to activate early last‐instar testes of both L. dispar and Heliothis virescens to synthesize ecdysteroid by exposing them to TE prepared from pupae of either species. Although testes of L. dispar contained no detectable ecdysone, they were able to convert (3H) ecdysone to 20‐hydroxyecdysone and a highly polar fraction. The active ecdysteroid product of L. dispar testes is probably 20‐hydroxyecdysone.
Maternal triiodothyronine injections cause increases in swimbladder inflation and survival rates in larval striped bass, Morone saxatilis
Authors: Brown Christopher L. , Doroshov Serge I. , Nunez Jose M. , Hadley Carl , Vaneenennaam Joel , Nishioka Richard S. , Bern Howard A. 
Published: June 2005

AbstractWe have experimentally elevated the triiodothyronine (T3) content of striped bass (Morone saxatilis) eggs by injecting female striped bass intramuscularly with a large dose of T3 (20 μg/g body weight) shortly before the induction of spawning. The significant elevation of T3 concentrations in the eggs from the hormone‐injected fish (to 180 ng per gram), compared with those of vehicle injected controls (about 19 ng/g), confirms the transfer of T3 from the maternal circulation into oocytes. There were significant differences in the development of embryos and larvae from the two groups. Within the first week after hatching, the hormone‐treated cohorts showed significantly greater larval body area, length, and dry weight, despite similar patterns of yolk and oil‐globule utilization. The rate of swimbladder inflation and the survival rate were also significantly enhanced in the cohorts produced by T3‐treated females. There was a positive and highly significant correlation between the concentration of T3 in the unfertilized oocytes and the rate of survival within the cohort. The improvement in larval survival may be a result of the maintenance of elevated T3 levels through the first week of development: during the transition to active feeding but before the onset of larval thyroid function. Thyroid hormone supplements appear to confer a distinct advantage to larval striped bass during this early, fragile developmental stage.
Role of mitotic asters in accumulation of pigment granules around nuclei in early amphibian embryos
Authors: Kobayakawa Yoshitaka 
Published: June 2005

AbstractPigment granules accumulate around nuclei during the cleavage stage in amphibian embryos (Kobayakawa, J. Embryol. Exp. Morphol., 88:293–302, 1985). In Rana rugosa embryos, this unidirectional intracellular transport of pigment granules was found to occur mainly at each mitotic stage of 4th to 6th cell cycles in vegetal blastomeres. Immunocytochemical staining confirmed the growth of astral rays that fully develop at anaphase and telophase in each mitotic stage and also suggested an association of pigment granules with the microtubules. Microtubule inhibitors suppressed the accumulation of pigment granules, which appears to depend, around nuclei, on microtubular structures, probably astral rays in mitosis.
A prolonged cartilaginous phase in newt forelimb skeletal regeneration
Authors: Libbin Richard M. , Singh Inder J. , Hirschman Albert , Mitchell Ormond G. 
Published: June 2005

AbstractThe morphologic events leading to the regrowth of the amphibian limb have long been known, yet it is poorly appreciated that even when the limb appears outwardly restored, its skeletal parts may be formed entirely of cartilage. To determine when forelimb skeletal ossification begins and is completed in the spotted newt Notophthalmus viridescens, limbs from animals that had sustained midhumeral amputations were examined at intervals of up to 270 days. At this time, most regenerated skeletal parts were undergoing ossification, but those of the wrist remained entirely cartilaginous. Calcium content of regenerated bones was deficient, and X‐ray diffraction analysis disclosed the presence of apatite crystals with minimally discernible orientation.
Effect of dopamine, cyclic AMP, and pericardial organs on sodium uptake and Na/K‐ATPase activity in gills of the green crab Carcinus maenas (L)
Authors: Sommer Michael J. , Mantel Linda H. 
Published: June 2005

AbstractInjection of 10−5 M dopamine or 10−6 M dibutyryl cyclic AMP (dbcAMP) into intact Carcinus maenas significantly increased influx of sodium from 100% sea water. Injection of pericardial organ (PO) extract, which contains dopamine, also increased influx of sodium. Animals injected with dopamine or PO extract and gills treated with dbcAMP in vitro showed increased Na/K‐ATPase activity in the microsomal fraction of the gills. These results suggest a mechanism for short‐term activation of Na/K‐ATPase when crabs are transferred to a dilute medium.
Effect of polyamines and palmitoyl‐coenzyme A on glucose‐6‐phosphate dehydrogenase from the hepatopancreas of the sea mussel Mytilus edulis L
Authors: Rodriguez‐Torres A. M. , Villamarin A. , Ramos‐Martinez J. I. 
Published: June 2005

AbstractAliphatic polyamines are able to relieve the inhibition of glucose‐6‐phosphate dehydrogenase (G6PDH) by palmitoyl‐coenzyme A (CoA). Of the polyamines assayed, spermine was the most effective in relieving this inhibition, followed by spermidine and ethylenediamine. These data suggest that the extent of the ability to relieve the inhibition depends on the number of amino groups in the polyamine.The polyamines act specifically on palmitoyl‐CoA to free G6PDH from the inhibition by acyl‐CoA. Polyamines also decrease the inhibition of G6PDH by NADPH. The combination of these two effects results in an observed increase in G6PDH activity.
Critical period for determining claw asymmetry in developing lobsters
Authors: Govind C. K. , Pearce Joanne 
Published: June 2005

AbstractThe pair of enlarged chelipeds or claws in the lobster Homarus americanus is differentiated into a major crusher claw with a closer muscle of slow fibers only and a minor cutter claw with a closer muscle of predominatly fast fibers. Claw placement is random and can be controlled by removing one claw in the juvenile 4th or 5th stage. This induces the contralateral intact claw to become a cruscher, while the regenerated claw develops into a cutter (Emmel, '08). Rearing lobsters with a substrate (oyster chips) promotes the development of class asymmetry, whereas a substrate‐free environment (smooth surface) promotes the development of paired cutter claws (Lang et al., '78). Consequently, by rearing lobsters with or without a substrate at selected periods of juvenile development, we have delimited the critical period for claw determination to the 5th stage. During this 2‐week period, the presence of a substrate for a period of at least five days is necessary for the development of claw asymmetry.
Evidence for regulation following amputation and tissue grafting in the developing mouse limb
Authors: Wanek Nancy , Muneoka Ken , Bryant Susan V. 
Published: June 2005

AbstractProcedures are now available to experimentally manipulate postimplantation mouse embryos in situ and allow development to continue into postnatal life (Muneoka, K., N. Wanek, and S.V. Bryant (1986) J. Exp. Zool., 239: 289–293). We have investigated the ability of the well formed hindlimb bud to regulate following two experimental operations: amputation and wedge grafts designed to confront anterior and posterior cells. After comparing the resultant limbs with the fate maps of the relevant states, we conclude that the developing hindlimb bud at stage 7/8 (equivalent to stage 27/28 of the chick) is capable of partial regeneration of the peripheral digits following amputation and capable of supernumerary digit tip formation after grafting of a wedge of anterior tissue to a posterior position.
Failure of fertilization following abbreviated copulation in the ferret (Mustela putorius furo)
Authors: Miller Brian J. , Anderson Stanley H. 
Published: June 2005

AbstractIn the first experiment, copulations in 10 domestic ferrets were interrupted 5 minutes after penetration. Ten control females were bred without interruption to the same males. Both control and experimental animals were rebred in the same manner to the same males 24 hours later. Sperm were present in all postcoital washes. We allowed all females from the first experiment to proceed to their expected data of parturition. All females who had been Interrupted during copulation failed to conceive, whereas all controls produced litters. In a second experiment, the same procedure was followed; however, in this experiment, ferret oviducts and uteri were flushed 10 days after copulation. Nine control females (one failed to ovulate) averaged 5.2 blastocysts (range 2–10; S.D. = 5.8) per animal. Of nine interrupted copulation ferrets (one failed to ovulate), only one animal produced a single blastocyst. The interrupted copulation group averaged 4.4 unfertilized eggs (range 2–10; S.D. = 5.0) per female. Although ferrets ovulated during short copulations, those eggs are not likely to be fertilized.
Oxygen binding of single red blood cells of the annelid bloodworm Glycera dibranchiata
Authors: Mangum C. P. , Colacino J. M. , Vandergon T. L. 
Published: June 2005

AbstractThe red blood cells of the annelid bloodworm Glycera dibranchiata contain two structurally and functionally distinct assemblages of hemoglobin. In the present sample the monomer comprised 57% and the polymer 43% of the total amount. The O2 affinities of the two differ by a factor of about two. Therefore, if the two assemblages occur in different cells, one would expect a bimodal distribution of P50 values for single RBCs and, if they coexist in the same cell, one would expect a monomodal distribution. The distribution is clearly monomodal, indicating no anatomical separation of mono‐ and polymeric hemoglobins.
Chemical access to the vomeronasal organs of the lizard Chalcides ocellatus
Authors: Graves Brent M. , Halpern Mimi 
Published: June 2005

AbstractA functional association between tongue flicking and vomeronasal organ chemoreception in lizards has been assumed frequently, but never tested. To test this hypothesis, a cotton swab soaked in prey extract mixed with [3H]proline was touched ten times to the snouts of normal and tongueless lizards (Chalcides ocellatus), as well as normal lizards whose vomeronasal organ (VNO) ducts had been sealed with a tissue adhesive. Additionally, such a swab was held approximately 0.5 cm in front of the snout of normal and tongueless lizards for 1 min, which allowed no contact by tongueless animals and tongue contact only by normal lizards. Using autoradiography, substantial and comparable concentrations of labeled molecules were detected in the mouths, VNO ducts, and VNOs of normal subjects in both conditions, as well as tongueless lizards whose snouts made physical contact with swabs. No label was evident in VNOs of tongueless animals that did not contact swabs or normal animals with sealed VN ducts. Labeling was not apparent generally in the olfactory epithelium. These results suggest that: 1) the tongue is not required for, nor does it increase, chemical delivery to VNOs when snout contact occurs; 2) the tongue transfers molecules from the external environment to the oral region; 3) it is unlikely that nonvolatile chemicals reach the olfactory epithelium via an oral route; and 4) tissue adhesive is an effective means of preventing chemical access to the VN organs.
Spermatolysins in Bufo arenarum: Their activity on oocyte surface
Authors: Cabada Marcelo O. , Manes Mario E. , Gomez Marta I. 
Published: June 2005

AbstractThe activity of spermatolysins from Bufo arenarum spermatozoa on spawned dejellied oocytes is studied at structural and ultrastructural levels. After adding spermatolysins to spawned dejellied oocytes, a wrinkling of the animal hemisphere is first observed under a stereomicroscope. Two or three minutes later, the vitelline envelope in the animal hemisphere is completely digested, which produces oocyte flattening. The vitelline envelope covering the vegetal hemisphere is not modified with the treatment. Ultrastructural observations indicate that while the vitelline envelope of the vegetal hemisphere remains unaltered, the animal counterpart gradually loses its components and finally all structures disappear. Scanning microscope observations reveal that the microvilii of the plasma membrane in the animal hemisphere decreases in number and length, while the vegetal region is not altered by the enzyme.