bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of lumicolchicine, colchicine and vinblastine on pigment migration in fish chromatophores
Authors: Obika Masataka , Turner William A. , Negishi Sumiko , Menter David G. , Tchen T. T. , Taylor John D. 
Published: June 2005

AbstractThe effects of lumicolchicine, colchicine, vinblastine and cold temperature on the pigment migration in melanophores and xanthophores of Fundulus heteroclitusand Oryzias latipeswere examined by light and electron microscopy. Xanthophores of both species which contain numerous microfila‐ments and a poorly developed microtubule system were extremely sensitive to the alkaloids. Lumicolchicine and colchicine induced irreversible dispersion while vinblastine caused permanent aggregation of the pigments. Treatment in lumicolchicine or colchicine at 5 mM for 60 minutes did not disrupt micro‐tubules of melanophores to an appreciable degree, however, melanosome aggre‐gation was partially inhibited by these drugs in Oryzias. When melanophores were kept in the cold in the presence of colchicine at 1 mM, almost all micro‐tubules were disrupted and their repolymerization at room temperature was nearly completely inhibited by colchicine. These melanophores lacking in mi‐crotubules responded to epinephrine with slow aggregation. Vinblastine at 0.1 mM induced partial aggregation of melanosomes and disruption of micro‐tubules but most melanophores were still able to respond with pigment migra‐tion. Vinblastine at 1 mM made all melanophores punctate and immobile. Large vinblastine‐induced crystals were frequently seen in the dendritic proc‐esses. The results of the present investigation suggest that cytoplasmic micro‐tubules in fish melanophores facilitate melanosome migration only in di‐rectional orientation and appear not to be responsible for the motive force.
Inositol pentaphosphate in fish red blood cells
Authors: Borgese Thomas A. , Nagel Ronald L. 
Published: June 2005

AbstractInositol pentaphosphate (IP5) has long been characteristic of avian erythrocytes. We now report that this compound is also present in the red cells of two species of elasmobranch fishes, Squalus acanthias (spiny dogfish) and Narcacion nobiliana (torpedo ray). The mean concentration of IP5 is 0.36 and 0.24 micromoles per ml of red cells respectively. ATP is the major organic phosphate in both fishes. 2,3‐diphosphoglycerate is absent and GTP levels correspond approximately to the levels of IP5.
Trochlear‐oculomotor nerve interactions in Xenopus laevis tadpoles: A temporal study
Authors: Fangboner Raymond F. 
Published: June 2005

AbstractWhen the trochlear nerve(NIV), which innervates the superior oblique muscle (SOM), is crushed or cut at stages 48–49 in Xenopus tadpoles, fibers from the oculomotor nerve (NIII) sprout and invade the SOM. The maximal percentage of specimens having at least one oculomotor nerve fiber on the SOM on a given day increased from 9.1% following a single crushing of NIV to 84.2% following three successive severings of NIV and the average number of silver‐impregnated NIII fibers per specimen increased from 0.23 ± 0.16 (mean ± S.E.M.) in the single‐crush experiment to 7.35 ± 1.33 in the triple‐cut experiment. This increase directly reflects the delay in the return of NIV. As NIV returns to the SOM, a portion of the inappropriate innervation is lost; while another portion appears to be stable and is in evidence 90 days after a single sectioning of NIV. The more rapidly NIV returns to the SOM, the more complete is the displacement of the NIII fibers. This suggests that the association between NIII and the SOM changes with time so that easy displacement of the inappropriate innervation is likely only when the reinnervation by the appropriate nerve fibers is rapid.
The origin of yolk‐DNA in Xenopus laevis
Authors: Opresko Lee , Wiley H. Steven , Wallace Robin A. 
Published: June 2005

AbstractXenopus laevis serum and plasma was found to contain an average of 25 μg DNA/ml. Isolated X. laevis oocytes incubated in medium containing 25 μg DNA/ml labeled with either 125I, 32P or 14C and from three different sources (bovine, E. coli and X. laevis), incorporated the label at an average rate of 0.11 ng·mm−·hr−1. Sucrose gradient fractionation of oocytes revealed that 40–75% of the acid‐precipitable label incorporated was associated with the yolk platelets. Additional incubations of oocytes in unlabeled medium demonstrated that the DNA incorporated into the yolk platelets was undergoing turnover; only 20% of the yolk‐associated DNA was still present after a one‐week incubation. Our data suggest that yolk‐DNA arises by the adventitious uptake of DNA present in the maternal serum by vitellogenic oocytes.
Reduction of sodium dependent stump currents disturbs urodele limb regeneration
Authors: Borgens Richard B. , Vanable Joseph W. , Jaffe Lionel F. 
Published: June 2005

AbstractWe have asked the question whether the natural electric currents which leave urodele limb stumps are in any way needed for their regeneration. As an initial test, we have greatly reduced such currents in the tiger salamander, Ambystoma tigrinum, by applying 0.5 mM amiloride to the stump skin or by immersion of the animals in sodium depleted media. We have also reduced such currents in the red spotted newt, Notophthalmus viridescens, by such immersion. Limb regeneration in half of the amiloride‐treated animals was either entirely blocked or grossly deficient, while the others regenerated normally. Limb regeneration in sodium depleted media was consistently inhibited for some weeks but then recovered.These results are consistent with the hypothesis that stump currents are in some way needed for normal regeneration.
Stages of forelimb regeneration in Ambystoma maculatum
Authors: Stocum David L. 
Published: June 2005

AbstractA series of normal stages describing the regeneration of larval A. maculatum limbs after amputation through the upper arm or wrist is described. Nine discrete stages were recognized, based on external morphological and associated histological features. These stages are Initial Dedifferentiation (ID), Early Bud (EB), Medium Bud (MB), Late Bud (LB), Early Redifferentiation (ER), Notch (N), 2‐Fingerbud (2‐FB), 3‐Fingerbud (3‐FB) and 4‐Fingerbud (4‐FB). Similarities and differences between this and other staging systems for urodele limb regeneration are discussed. The absence of osteoclasts was a striking feature during dedifferentiation of the wrist, in contrast to their presence in large numbers during dedifferentiation of the upper arm.
Reproductive failure and maternal‐fetal relationship in a Peromyscus species cross
Authors: Maddock M. B. , Chang M. C. 
Published: June 2005

AbstractMating, fertilization, implantation, prenatal mortality, fetal and placental size, and placental ultrastructure were studied in intraspecific and interspecific crosses involving Peromyscus maniculatus and P. polionotus. Failure to mate was a major factor in interspecific crosses and was much more pronounced in crosses between P. polionotus females and P. maniculatus males than in the reciprocal cross. Failure of implantation following mating, however, was more pronounced in crosses between P. maniculatus females and P. polionotus males. Failure of implanted embryos to survive to term was a factor in crosses between P. polionotus females and P. maniculatus males. Comparison of the placental labyrinth of conceptuses from intraspecific and interspecific crosses revealed no differences at the ultrastructural level. The relationship of these observations to the evolution of isolating mechanisms in mammals and to physiological aspects of the developing maternal‐fetal relationship are discussed. A model of placental and fetal size inheritance is presented.
The distribution of cells in the upper forelimb of the axolotl, Ambystoma mexicanum
Authors: Tank Patrick W. , Holder Nigel 
Published: June 2005

AbstractThe number and relative density of cells in specific regions of the upper forelimb of the axolotl were compared. Selected transverse sections taken from the distal one‐third of the upper forelimb were analysed by light microscopy. Comparisons were made between the total numbers of cells observed in each of the major tissue components of the forelimb (epidermis, dermis, muscle, connective tissues and skeletal tissues). Comparisons were also made between the total numbers of cells located in the major limb quadrants (anterior, posterior, dorsal and ventral). In addition, cellular density (cells/mm2) was compared among eight limb sectors. The results indicate that the posterior quadrant of the upper forelimb contains more cells than any other forelimb quadrant. Cellular density did not favor a particular forelimb quadrant. These results suggest that the proposed clumping of positional values in the posterior region of the forelimb in the axolotl (Tank, unpublished data) may correspond to the presence of a larger number of cells in the posterior quadrant, but does not correspond to a higher cellular density in that region of the upper forelimb.
Separation of the epithelial and mesenchymal components of the newt limb regenerate with salt
Authors: Jasch Laura G. 
Published: June 2005

AbstractAfter incubation of isolated forelimb regenerates of Notophthalmus (Triturus) viridescens at all developmental stages for 60 minutes at 37°C in a salt medium containing 111 mM sodium chloride, 5.6 mM potassium chloride and 100 mM sodium phosphate buffer at pH 7.5, the wound epithelium of each regenerate was removed intact from its underlying mesenchymal component. The suggestion is made that the salt medium is an effective epithelialmesenchymal separating agent due to a combination of its hypertonicity, high ionic strength and the fact that the medium precipitates calcium as calcium phosphate. Attempts to dissect away the epithelium from the mesenchyme after incubation of isolated regenerates in sodium phosphate containing 1% or 3% Difco 1:250 trypsin, 10 mM EDTA or 150 units collagenase/ml medium were unsuccessful. Epidermis of adult newt forelimb skin was removed only after extended incubation of the forelimbs in the salt medium for three hours at 37°C or after freezing isolated forelimbs in buffer and subsequent thawing.
Comparison of DNA polymerase activity and cell division in normal and delayed‐implanting mouse embryos
Authors: Weitlauf H. , Kiessling A. , Buschman R. 
Published: June 2005

AbstractCell division stops in mouse blastocysts during the prolonged, free‐living phase associated with delayed implantation. It is not known how the embryos are rendered mitotically dormant and then reactivated to implant at a later time, and the present experiments were undertaken to determine whether or not changes in the level of DNA polymerase in the embryos could play a role in the regulation of cell division.Unattached normal and delayed‐implanting blastocycts were recovered from pregnant mice at intervals between the fourth and the fifteenth day of pregnancy, and the number of cells and amount of DNA polymerase in the embryos were determined in order to correlate amount of enzyme with the rate of cell division. The number of cells in both types of embryos increased equally until noon of day 5. However, as expected, the rate of cell division in the delayed implanting blastocysts then slowed and there was no further increase in the number of cells beyond day 7 or 8. Termination of the dormant phase of delayed implantation by the injection of 17 β‐estradiol, resulted in a resumption of cell division within 24 hours. The total amount of DNA polymerase activity in normal blastocysts increased 200% between day 4 and day 5. In contrast, there was only a 60% increase in enzyme activity in the delayed implanting embryos during this interval. The level of polymerase activity in the delayed implanting embryos then decreased and remained depressed for the several days of the dormant period. Injecting 17 β‐estradiol on day 9 resulted in an increase (120%) in polymerase activity. Although the amount of DNA polymerase per cell in the dormant embryos was low by comparison with that in normal embryos, it was higher than that in adult spleen (a tissue that is active in DNA synthesis) and therefore it appears likely that other mechanisms are involved in regulating cell division in the embryos.
Liquid chromatographic demonstration of catecholamine release in fish heart
Authors: Cameron John S. , O'Connor Edward F. 
Published: June 2005

AbstractHigh‐pressure liquid chromatography (HPLC) was used to assay for catecholamines released into the heart of the goldfish (Carassius auratus L.) upon stimulation of vagal nerve fibers. Stimulation induced the release of norepinephrine, epinephrine and dopamine into the lumen of the perfused, isolated heart. The results suggest that heart activity in teleosts is directly modulated by functional adrenergic, cardioacceleratory nerve fibers.
Modifications in the arrangement of thick and thin filaments in transforming shrimp muscle
Authors: Mellon DeForest , Stephens Philip J. 
Published: June 2005

AbstractThe fine structure and arrangement of thick and thin filaments in the main closer muscle were investigated for pincer, snapper and transforming claws of Alpheus armillatus. The snapper main closer muscle is composed of a uniform population of tonic‐type fibers with long sarcomeres and a thin‐to‐thick filament ratio of 7 to 1. In contrast, the pincer main closer muscle is made up of two populations of fibers. Phasic type fibers have large diameters, short sarcomeres and a thin‐to‐thick filament ratio of 3 to 1. Intermediate‐type fibers have smaller diameters, intermediate sarcomere lengths and a thin‐to‐thick filament ratio of between 5 and 6 to 1. In the pincer the thick filaments have a hollow appearance. During the transformation of a pincer to a snapper claw, the main closer muscle fibers develop tonic‐type characteristics. The sarcomeres increase in length, and the ratio of thin‐to‐thick filaments increases to 7 to 1. Furthermore, the thick filaments increase in both length and diameter, and develop a more uniform structure. These findings suggest that changes in myosin packing accompany transformation, with predictable consequences in both thick filament diameter and thin filament/thick filament ratio.
Alteration of locomotor behavior in wolf spiders carrying normal and weighted egg cocoons
Authors: Moffett Stacia , Doell Gail S. 
Published: June 2005

AbstractThe slow locomotion (5–11 cycles/sec) of unloaded wolf spiders, Pardosa tristis, was compared with that of spiders moving at similar speeds supporting a normal or an artificially weighted egg cocoon attached to the opisthosoma or in the pedipalps. Spiders carrying an egg cocoon attached to the opisthosoma elevated the opisthosoma, while spiders carrying a cocoon in the pedipalps elevated the prosoma and curved the opisthosoma downward. Both loaded groups gathered their legs more closely under them and took shorter steps than unloaded spiders. Protraction/retraction ratios increased as a function of increasing walking speed and decreased as a function of increasing loads.
Study of intraclonal conjugation in Chilodonelia steini. Evidence of abortive conjugation
Authors: Kaczanowski Andrzej , Radzikowski Stefan , Malejczyk Jacek , Polakowski Igor 
Published: June 2005

AbstractMating and conjugation in the ciliate Chilodonella steini has been examined. Only intraclonal conjugation has been found thus far in this species. Stable opposite mating types have not been observed, even after extensive single cell isolations and the observation of cell lines following two consecutive generations of inbreeding. Following intraclonal conjugation, two kinds of selfing lines appear: 1) lines that enter long immaturity periods, 2) lines that do not enter immaturity at all, but maintain a permanent ability to pair. These lines do not yield immature progeny after a subsequent conjugation. Immature lines result from true conjugation as expected, whereas those lines that do not enter immaturity result from an abortive process. During normal conjugation the new macronuclear anlagen develop and the old macronucleus is resorbed. During abortive conjugation the new macronuclear anlagen also develop but the old macronucleus is not resorbed. Eventually the old macronucleus, instead of the new one, divides to provide a somatic nucleus for the progeny. Thus macronuclear retention occurs in some lines of Ch. steini similar to that observed in senescent lines of Tetrahymena thermophila.
Potentiation of the cGMP‐induced Guinea pig acrosome reaction by zinc
Authors: Santos‐Sacchi Joseph , Gordon Mildred , Williams William L. 
Published: June 2005

AbstractThe addition of 8 bromo cGMP (10 mM) immediately (∼2 min) upon suspension of Guinea pig sperm in glucose‐free BWW medium induces a significant number of acrosome reactions within minutes. The simultaneous addition of micromolar concentrations of ZnCl2 (25–1000 μM) potentiates the cGMP effects. Mid‐micromolar concentrations were able to dramatically increase the percentage of acrosome reactions by a factor of 6.5 over 8 bromo cGMP alone. The induction of acrosome reactions was dependent upon external Ca++, and it is suggested that in this species Zn++ flnctions by affecting cyclic nucleotide metabolism and/or Ca++ flux.
The effect of pinealectomy on hibernation in two species of seasonal hibernators, Citellus lateralis and C. richardsonii
Authors: Harlow Henry J. , Phillips John A. , Ralph Charles L. 
Published: June 2005

AbstractPinealectomies and radical sham pinealectomies were performed on golden‐mantled and Richardson's ground squirrels approximately 1 month prior to the date of normal immergence for each species. Pinealectomy did not disrupt the hibernating rhythm of either species. These results suggest (1) that the pineal is not required for torpor to be initiated or maintained, (2) that either melatonin is not required for hibernation or another melatonin‐producing organ compensates for the loss of the pineal, and (3) that the influence of the pineal is seasonal and had already acted prior to its surgical removal.
Methemoglobin reduction in crocodile blood: Are high levels of MetHb typical of healthy reptiles?
Authors: Gruca Margie , Grigg Gordon C. 
Published: June 2005

AbstractIn 82 wild‐caught Crocodylus porosus, levels of NADH‐MetHb reductase and GSH seem adequate to maintain hemoglobin in its reduced functional state. Studies of C. porosus erythrocytes in vitro show reduction of metHb in the presence of lactate, glucose and plasma, but not pyruvate.These findings, together with recent data which show low metHb in a variety of reptiles, cast doubt on the accepted view that high levels of MetHb are typical of healthy reptiles.One explanation for the sharp contrast between earlier and more recent data could be technical. We found low metHb in Crocodylus johnstoni, Chelodina longicollis and Sphenomorphus quoyi. However, high and variable values reminiscent of many of the earlier data were obtained by omitting final centrifugation prior to spectrophotometry. Interestingly, this step is not part of the standard clinical method but is necessary in analyses of blood with nucleated red cells. These observations suggest that high metHb may not be typical of reptiles after all.
The effects of constant light and constant darkness on the pineal organ of the goldfish, Carassius auratus
Authors: McNulty John A. 
Published: June 2005

AbstractGoldfish (Carassius auratus) were subjected to both long‐ and short‐term (1, 3, 6, and 170 days) constant light or constant darkness to determine the effects of environmental lighting on the morphology of photoreceptor cells in the pineal organ. Morphometric analysis of electron micrographs from each experimental group suggested that the effects of constant darkness are morphologically expressed only after long‐term (6 months) exposure. These included an increase in the volume of photoreceptor and phagocytic cells, area of rough endoplasmic reticulum, and volume of mitochondria per photoreceptor cell, and a decrease in the size of individual Golgi bodies. On the other hand, the response to constant light occurred generally within the first 6 days. Under these conditions, there was a reduction in outer‐segment volume, but an increase in both the volume of Golgi per photoreceptor cell and size of individual Golgi bodies. Synaptic ribbons in these specimens were longer at every time sampled. The results of this study provide evidence that photoreceptor cell organelles involved in synthesis and secretion, as well as photosensory functions, are influenced by environmental lighting.
Dissection of circadian organization of Aplysia through connective lesions and electrophysiological recording
Authors: Roberts Michael H. , Block Gene D. 
Published: June 2005

Abstract(1)Aplysia californica exhibit a diurnal circadian locomotr rhythm (Strumwasser, '67). The rhythm appears to be timed by circadian pacemakers located within the eye, although extraocular photoreceptors and pacemakers also influence locomotor behavior (Strumwasser, '73; Lickey et al., '77). (2) The present study was undertaken in an attempt to identify the pathways ganglia, which are responsible for generatating locomotor movements. A lesion study was performed in which either of the two pairs of bilaterally symmetrical cerebral connectives were cut and the effect on locomotor behavior evaluated. (3) The results indicate that the cerebro‐pleural connectives are not involved in control of locomotor acitivity (Fig. 2). On the other hand, the cerebro‐pedal connectives are critical for ocular and extraocular control of locomotor thythmicity (Figs. 3,4). Animals with bilateral cerebropedal lesions are arrhythmic on light cycles. (4) Multiunit recording in vivo and in vitro revealed the presence of a descending signal in the cerebropedal connective upon the application of a light pulse to the animal. Further experimentation localized the origin of these signals to the tentacles, rhinophores and eyes (Figs. 6, 7). (5) We conclude that the elements comprising the circadian system of Aplysia are located in a restricted portion of the central nervous system including the cerebral and buccal ganglia, and sensory structures served by cerebral or buccal nerves.
Can differences in limb regeneration ability between amphibian species be explained by differences in quantity of innervation?
Authors: Scadding Steven R. 
Published: June 2005

AbstractThis investigation was designed to test the hypothesis that there is a direct relationship between quantity of innervation and regenerative capacity. This was done by measuring the quantity of innervation in 13 different species of amphibians chosen to represent a spectrum of regenerative abilities. When looking at the five urodele species alone, or when comparing urodeles and eight anuran species, the results show a lack of correlation between regenerative capacity and quantity of innervation. However, if the anurans alone are considered, the four species in which regeneration has been observed all have levels of innervation greater than in the four species that do not regenerate. This suggests the possibility that an adequate quantity of innervation may be a limiting factor for limb regeneration in anurans, but is not a limiting factor in urodeles.