bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of nonlimb tissues on forelimb regeneration in the axolotl, Ambystoma mexicanum
Authors: Tank Patrick W. 
Published: June 2005

AbstractPrevious studies with Notophthalmus viridescens have shown that forelimb stumps covered by flank skin do not regenerate when amputated through the graft of nonlimb skin [Tank, P.W. (1984) J. Exp. Zool., 229:143–153]. In an attempt to determine whether or not cells derived from nonlimb skin dedifferentiate and enter the regeneration blastema, four experimental series were prepared using triploid (3N) marked cells grafted into diploid (2N) hosts of the axolotl (Ambystoma mexicanum). In the first series, head skin was used to replace limb skin followed by amputation through the graft 30 days later. Fully 96% (24/25) of the limbs failed to regenerate an externally visible outgrowth and 4.4% of the blastemal mesenchyme cells were observed to be 3N based on the characteristic of three nucleoli per nucleus. In the second series, flank skin replaced limb skin and 38% (8/21) of the limbs failed to regenerate. The remaining limbs regenerated an assortment of hypomorphic, normal, abnormal, or multiple structures. Only 2.4% of the cells in the blastemal mesenchyme were observed to be 3N in the second series. In the third series, head dermis was implanted in place of limb musculature and 20% (3/15) of the limbs failed to regenerate. The other limbs in series three were either abnormal, hypomorphic, or multiple in morphology. Histological analysis revealed that 3.4% of the cells in the blastemal mesenchyme of the head dermis group were 3N. In the fourth series, flank dermis replaced limb musculature and only 7% (1/15) failed to regenerate. Ten limbs (66%) formed hypomorphic regenerates and the remainder were normal, abnormal, or multiple in morphology. Histological analysis revealed that 6.8% of the cells were 3N in the blastemal mesenchyme of limbs in series four. Sham‐operated controls for all four series regenerated normally and histological analysis of contralateral control limb regenerates revealed background 3N marker that averaged from 0.1 to 0.8%. The regenerate epidermis of limbs that were covered by 3N head skin or flank skin contained approximately 25% 3N cells, indicating that the epidermis was of nonlimb origin. The regenerate epidermis of limbs bearing 3N dermis implants did not contain marked cells. These results indicate that non‐limb cells are capable of undergoing dedifferentiation and entering the limb regeneration blastema. An explanation of regenerative failure is provided that is based on interference with short range cellular interactions by nonlimb cells.
A kinematic study of front legs' movements in walking Protura (Insecta)
Authors: Tichy Harald 
Published: June 2005

AbstractHigh‐speed cine film of walking Protura shows that a) the forward projected legs 1 move almost parallel to the body; and b) their point of contact with the ground is only in front of the coxal articulation. The average stride length of legs 1 (0.05 mm) measures one‐third that of legs 2 and legs 3 (0.15 mm). These features indicate a relatively small contribution of the front legs in supporting and propelling the animal, which is accomplished by a pulling rather than a pushing action. On a horizontal rough surface of moist plaster, the animal moves by three fashions: a) it holds up the front legs and walks with the middle and rear legs, b) it places occasionally one or both front legs on the ground while walking with the middle and rear legs, and c) it uses all six legs in walking. In the latter case the average promotion duration of legs 1 (0.29 s) is twice that of legs 2 and 3 (0.15 s each), whereas the average remotion duration of legs 1 (0.08 s) is one‐half that of legs 2 and 3 (0.17 s). In addition, the movements of legs 1 are not coordinated with the other two pairs in the typical hexapode stepping pattern. Instead, they are used independently with a tendency to alternating up and down movements. These specializations of legs 1 reflect an exploratory role in walking. On a horizontal slippery surface of transparent paper, the animal walks exclusively with six legs. In all legs, the duration of the remotion period increases as the time elapses in a series of walks. In legs 2 and 3 the remotion duration is longer than that of promotion throughout the experiment, but in legs 1 it changes from shorter to longer. Timing of the front legs' movements does not fit in the hexapode rhythm. Legs 1 are both simultaneously and alternatingly used, thus playing a part in propelling and balancing the body.
Potassium channel blockers unmask electrical excitability of insect follicles
Authors: O'Donnell M. J. 
Published: June 2005

AbstractStandard techniques for intracellular recording and current injection were used to determine if the developing ovarian follicles of six species of insect were electrically excitable. Follicles were dissected from the panoistic ovarioles of Locusta migratoria and Periplaneta americana, the polytrophic meroistic ovarioles of the fruit fly Drosophila rnelanogaster and the silkworm moths Hyalophora cecropia and H. Columbia, and the telotrophic meroistic ovarioles of the mealworm beetle Tenebrio mlitor. Follicles of all species except Tenebrio were inexcitable in control saline; Tenebrio follicles produced short action potentials which did not outlast the duration of the current pulse. Follicles of all species except Drosophila produced long duration overshooting action potentials when depolarized in salines containing the potassium channel blockers tetraethylammonium (TEA; 10–80 mM), Bazf (10–20 mM) and 4‐aminopyridine (4‐AP; 10 mM). Hyalophora follicles were also excitable in saline containing TEA and Ba2+ but not 4‐AP, and Tenebrio follicles were excitable in saline containing Ba2+ but not TEA and 4‐AP. Excitability in follicles of all species was unaffected by sodium replacement but was reversibly inhibited by the calcium channel blockers La3+ (1 mM), Co2+(10 mM), or verapamil (0.1‐1.0 mM). It is suggested that the action potentials are caused by the movement of calcium or barium through voltage‐dependent channels that are masked in control saline by a large counteracting potassium conductance. Excitability appears to be a property of the oolemma and not the follicle cell membranes. Possible functions of voltage‐dependent ion channels in insect oocytes are discussed.
The physiological basis of slow locomotion in chamaeleons
Authors: Abu‐Ghalyun Younis , Greenwald Lewis , Hetherington Thomas E. , Gaunt Abbot S. 
Published: June 2005

AbstractThe African chamaeleon, Chamaeleo senegalensis, will not move faster than ∼0.1 m/second at 23 °C, whereas the lizard Agama agama, like most lizards its size, runs at speeds more than 10 × as fast. To account for this difference, we measured various physiological parameters of the iliofibularis muscle of both lizards. The maximum speed of tetanic contraction of unloaded Chamaeleo muscle was half as fast as that of Agama muscle (2.5 vs. 5.8 resting lengths per second). Heavily loaded Chamaeleo iliofibularis contracted at nearly ¼ the speed of Agama muscle. Time to peak isometric twitch tension and time to half relaxation were twice as long in Chamaeleo as in Agama (122 vs. 58 msec, and 168 vs. 81 msec). Much more of the Chamaeleo muscle consisted of tonic muscle fibers, and the Chamaeleo muscle, compared to Agama muscle, showed physiological evidence of having a significant amount of tonic fibers (potassium contracture and high tetanus to twitch ratios). Finally, the myofibrillar ATPase activity of the Chamaeleo muscle was ⅓ that of Agama muscle. Thus, these results show that the slow locomotion of old world chamaeleons can, in part, be explained by the physiology, biochemistry, and fiber‐type distribution of their muscles.
Cellular retinoic acid binding protein: Detection and quantitation in regenerating axolotl limbs
Authors: McCormick Anne M. , Shubeita Huda E. , Stocum David L. 
Published: June 2005

AbstractThe concentrations of apo (unoccupied), holo (occupied), and total cellular retinoic acid binding protein (CRABP) were measured at various stages of axolotl limb regeneration. The ratio of apo‐CRABP to holo‐CRABP declined with advancing regenerate stage until the CRABP was all in the holo form. The increase in holo‐CRABP is correlated with a stage‐dependent shift in the effect of exogenous retinoic acid on regenerate pattern, from pattern duplication to inhibition of regeneration. The data suggest, though they do not prove, that these different morphological effects could be due to a shift from a CRABP‐dependent to a CRABP‐independent mechanism of exogenous retinoic acid (RA) action that is related to stage‐specific variations in endogenous RA levels.
Effects of theophylline on expression of the long cilia phenotype in sand dollar blastulae
Authors: Riederer‐Henderson Mary Ann 
Published: June 2005

AbstractPreviously, increases in ciliary length have only been obtained through genetic mutation in Chlamydomonas or by incubation of swimming echinoderm blastulae in trypsin or elastase. We have found that the phenotypic switch from short to long cilia on sand dollar blastulae can also be effected by incubation in theophylline. Cilia detached from control blastulae have a mean length of 21 ± 7 μm with 10% of the cilia being > 30 μm. Upon incubation in 10 mM theophylline additional long cilia appeared after 10 hours and by 24–32 hours 1/2–3/4 of the embryo was covered with long cilia. The percentage of long cilia increased to 65% with a mean length of 40.0 ± 17.6 μm. Incubation in other methylxanthines, such as aminophylline, caffeine, or isobutylmethylxanthine, inhibited development but had no effect on ciliary length distribution. Dibutyryl cAMP, 8‐bromoad‐enosine, and calcium ionophore also had no effect on ciliary length. Cyclic AMP levels were measured and showed only slight differences among controls and embryos incubated in trypsin, caffeine, or theophylline. These data suggest that theophylline may be altering ciliary length control through some mechanism other than elevations in cAMP.
Localization of cortical granule constituents before and after exocytosis in the hamster egg
Authors: Cherr Gary N. , Drobnis Erma Z. , Katz David F. 
Published: June 2005

AbstractElectrical activation of the hamster egg was used to study cortical granule constituents before and after exocytosis. The activated hamster eggs underwent cortical granule decondensation just prior to and at the time of exocytosis. Some of the cortical granules of aged, unactivated eggs underwent similar changes. FITC‐ and gold‐conjugated Lens Culnaris agglutinin (LCA) bound intensely to the surfaces of activated but not unactivated eggs. This labelling was associated with the microvilli. Permeabilized eggs exhibited discrete cortical labelling before activation, with a subsequent decrease following the cortical reaction. Gold‐conjugated LCA specifically bound to cortical granules when incubated with thin sections. FITC‐soybean trypsin inhibitor (SBTI) bound in discrete foci in the cortex of unactivated eggs. Following activation, cortical labelling by SBTI decreased. Aprotinin and benzamidine hydrochloride inhibited FITC‐SBTI from binding to the egg cortex. Gold‐avidin localization of biotin‐SBTI in the electron microscope demonstrated that condensed cortical granules did not bind SBTI but decondensed or exocytosing granules did. This suggests that a cortical granule protease is exposed just prior to exocytosis. Activated eggs exhibited dramatic decreases in the number of hamster sperm penetrating the cytoplasm, suggesting that a plasma membrane block to polyspermy is temporally related to cortical granule exocytosis.
Properties of standard avian slow muscle grafts following long‐term regeneration
Authors: Hather Bruce M. , Hikida Robert S. 
Published: June 2005

AbstractThe tonic anterior latissimus dorsi (ALD) of adult pigeons was orthotopically homografted and evaluated after 11 months of regeneration for histological, histochemical, electromyographic (EMG), and mechanical properties. The resting EMG activity of the grafts was lower in amplitude than that of the controls, but showed the tonic pattern typical for these tonic muscles. The control and grafted muscles had a histochemically homogeneous population of fibers with moderate myofibrillar adenosine triphosphatase activity. Succinic dehydrogenase activity was moderate for the control muscles, but low for the grafts. The regenerated muscles had fewer and smaller fibers and had much larger intersynaptic distances. Both the regenerated and the contralateral control muscles were slow contracting and maintained tetanic tension for prolonged periods with direct electrical stimulation. The relaxation was slower in the grafted muscle than in the control. The grafts produced 40% of the maximum tension of the control muscles, but the rate of tension development was similar between the two groups. The results indicate that the tonic properties were regenerated, but the innervation pattern was altered and the grafted muscles did not have normal mature fibers even after long‐term regeneration.
Characterization of enzymes that degrade crab exoskeleton: II. Two acid proteinase activities
Authors: O'Brien Jack J. , Skinner Dorothy M. 
Published: June 2005

AbstractSpecific proteins extracted from the membranous layer of the exoskeleton of the Bermuda land crab, Gecarcinus lateralis, are degraded at acid pH values by two proteinase activities (AP I and AP II) extracted from integumentary tissues. The pH optimum of AP I was about 5; it does not bind to cation exchange resin and was strongly inhibited by pepstatin A. The pH optimum of AP II was about 4; it binds to a cation exchange resin and was inhibited by cysteine proteinase inhibitors. AP II shared some characteristics with the human lysosomal proteinase cathepsin B. Unlike cathepsin B, which binds to the cysteine proteinase inhibitor E‐64 in a 1:1 ratio, AP II was not completely inhibited by E‐64, and only at the lower concentrations of inhibitor was there a linear relationship between enzyme activity and amount of inhibitor.
Skull development during anuran metamorphosis: III. Role of thyroid hormone in chondrogenesis
Authors: Hanken James , Summers Cliff H. 
Published: June 2005

AbstractMetamorphosis of cranial cartilages in anuran amphibians constitutes one of the most dramatic and extensive ontogenetic transformations in vertebrates. We quantitatively examined the role of thyroid hormone (3,3′,5‐triiodo‐L‐thyronine; T3) in mediating gross aspects of this morphological repatterning in the skull of the Oriental fire‐bellied toad, Bombina orientalis. T3 was administered via plastic (Elvax) micropellets in three treatment dosages (2.5, 0.25, and 0.025 μg) and one control dosage (0 μg) to tadpoles of three Gosner developmental stages–28/29, 30/31, and 32/33; tadpoles were recoved up to 8 d (treatment and control dosages) or 14 d (control dosage) later. Response of larval cartilages to exogenous T3 was dosage dependent but not implant‐stage dependent; chondrogenic tissues that participate in metamorphic transformation are competent to respond to T3 well before they normally do. Metamorphic effects of T3 were visible within 2 d; in most treatment groups, the normal metamorphic sequence was two‐thirds complete after 8 d. While T3 also induced precocious ossification, the normal temporal relation between bone formation and cartilage transformation was dissociated in experimental groups. Morphological integration between cartilage and bone during cranial metamorphosis is at least partly the result of each tissue responding independently to endocrine factors.
Locomotion of sponges and its physical mechanism
Authors: Bond Calhoun , Harris Albert K. 
Published: June 2005

AbstractActive locomotion by individual marine and freshwater sponges across glass, plastic and rubber substrata has been studied in relation to the behavior of the sponges' component cells. Sequential tracing of sponge outlines on aquarium walls shows that sponges can crawl up to 160 μm/hr (4 mm/day). Time‐lapse cinemicrography and scanning electron microscopy reveal that moving sponges possess distinctive leading edges composed of motile cells. Sponge locomotion was found to be mechanically similar to the spreading of cell sheets in tissue culture both with respect to exertion of traction (which causes the wrinkling of rubber substrata) and with respect to the patterns of adhesive contacts formed with the substratum (as observed by interference reflection microscopy). Other similarities include the orientation of sponge locomotion along grooves and the preferential extension onto more adhesive substrata. Neither the patterns of wrinkling produced in rubber substrata nor the distributions of adhesive contacts seen by interference reflection microscopy show evidence of periodic, propagating waves of surface contractions, such as would be expected if the sponges' mechanism of locomotion were by peristalsis or locomotory waves. Our observations suggest that the displacement of sponges is achieved by the cumulative crawling locomotion of the cells that compose the sponge's lower surface. This mode of organismal locomotion suggests new explanations for the plasticity of sponge morphology, seems not to have been reported from other metazoans, and has significant ecological implications.
Sex pheromone in a marine polychaete: Determination of the chemical structure
Authors: Zeeck Erich , Hardege Jörg , Bartels‐Hardege Helga , Wesselmann Günter 
Published: June 2005

AbstractA sex pheromone of the marine polychaetePlatynereis dumeriliiis chemically characterized as 5‐methyl‐3‐heptanone. There exist two optical isomers, the S(+)‐isomer produced by males and acting on females, the R(−)‐isomer produced by females and acting on males. The basic structure shows a close relationship to insect pheromones and is of interest with regard to the evolution of pheromones.
Direct observation of cold‐shock effects in ram spermatozoa with the use of a programmable cryomicroscope
Authors: Holt W. V. , Morris G. J. , Coulson G. , North R. D. 
Published: June 2005

AbstractCryoinjury in individual ram spermatozoa was investigated in cells cooled at 10°C/min on a programmable Cryomicroscope. In physiological buffer and cryoprotective media, there was a smooth decline in sperm swimming speed with decreasing temperature; cooling in buffer caused a marked decline in the proportion of cells displaying forward progression, especially once the temperature fell below 16°C. Spermatozoa cooled in the presence of rhodamine 123, a mitochondrial‐specific dye, showed that abolition of sperm motility by cold shock in buffer was not due to mitochondrial inactivation. Temperature decline through the region of 10°C caused a number of spermatozoa in buffer to undergo a sudden asymmetric bending of the flagellum in the region of the midpiece. Ultrastructural studies suggest that this was caused by an unstable, asymmetric membrane lesion. Spermatozoa cooled in the presence of cryoprotective media showed better recovery of motility after rewarming and failed to exhibit the bending effect described above.
Serum high‐density lipoprotein in the crab, Cancer antennarius Stimpson: II. Annual cycles
Authors: Spaziani Eugene 
Published: June 2005

AbstractHemolymph lipoproteins in crustaceans are of the high‐density type (HDL). Serum concentrations of HDL were measured monthly during 1982–1987 in crabs (Cancer antennarius) collected off the coast of Southern California. The annual profiles of concentrations feature female‐specific elevations during October–December, with the peak in November being an average four‐fold higher than the lows of early summer. The single departure from this pattern occurred in February–March, 1983, coinciding with a rise in water temperature due to the El Nino phenomenon. Females collected in most months were in various stages of egg maturation and brooding females also could be found at any time of year. Despite this heterogeneity, evidence supports an hypothesis that the annual increase in serum HDL occurs when most females in the population are actively vitellogenic.
Differential expression of the C4 isozyme of lactate dehydrogenase (LDHC4) in developing bonefish (Albula sp.)
Authors: Pfeiler Edward , Vrijenhoek Robert C. 
Published: June 2005

AbstractStarch‐gel electrophoresis revealed that the C4 isozyme of lactate dehydrogenase (LDHC4) predominated in the gelatinous, postcranial body mass of metamorphosing leptocephalous larvae of the bonefish (Albula sp.), a primitive teleost fish. At the end of metamorphosis, when the juvenile stage was reached and the gelatinous matrix had been resorbed and replaced by muscle and bone, the relative activity of the C4 isozyme was reduced, and the expression of the A4 and B4isozymes increased. The A4 isozyme then became the dominant form in white muscle of developing juveniles. The C4 isozyme was also expressed in juvenile eye, liver, heart, brain, gut, gill, and red muscle, but the B4 isozyme showed the highest relative activity in these tissues. These results suggest (1) that the Ldh‐C gene is the most active of the three LDH genes in the leptocephalus, (2) that the C4 isozyme of LDH performs a critical and specific function in larval metabolism, and (3) that metamorphosis is accompanied by tissue‐specific increases in activity of the Ldh‐A and Ldh‐B genes.
Evidence that regenerative ability is an intrinsic property of limb cells in Xenopus
Authors: Sessions Stanley K. , Bryant Susan V. 
Published: June 2005

AbstractXenopus laevis, exhibits an ontogenetic decline in the ability to regenerate its limbs: Young tadpoles can completely regenerate an amputated limb, whereas post metamorphic froglets regenerate at most a cartilagenous “spike.” We have tested the regenerative competence of normally regenerating limb buds of stage 52–53 Xenopus, tadpoles grafted onto limb stumps of postmetamorphic froglets. The limb buds become vascularized and innervated by the host and, when amputated, regenerate limbs with normal or slightly less than normal numbers of tadpole hindlimb digits. Reciprocal grafts of froglet forelimb blastemas onto tadpole hindlimb stumps resulted in either autonomous development of tadpole hindlimb structures and/or formation of a cartilaginous spike typical of froglet forelimb regeneration. Our results suggest that the Xenopus, froglet host environment is completely permissive for regeneration and that the ability to regenerate a complete limb pattern is an intrinsic property of young tadpole limb cells, a property that is lost during ontogenesis.
Triiodothyronine increases translatable albumin messenger RNA in Rana catesbeiana tadpole liver
Authors: Schultz James J. , Price Margaret P. , Frieden Earl 
Published: June 2005

AbstractThe effects of both 3,5,3′‐triiodo‐L‐thyronine and spontaneous metamorphosis on Rana catesbeiana, liver mRNA were studied using in vitro translation of isolated liver poly(A)+ RNA in a rabbit reticulocyte lysate system. Conventional phenol extraction methods yielded degraded RNA due to high levels of endogenous ribonucleases released upon homogenization of Rana catesbeiana, liver. Isolation of intact total RNA was achieved using the potent ribonuclease denaturant, guanidinium thiocyanate. Adult bullfrog serum albumin was purified to homogeneity and a monospecific antibody was elicited against it. A serum protein of 23,000 daltons that migrated near serum albumin on a 6% native gel was also purified to homogeneity. A monospecific antibody was also raised against this protein. Both antibodies were used to quantitatively immunoprecipitate the in vitro translation products of poly(A)+ RNA isolated at intervals following a single injection of triiodothyronine or during various stages of spontaneous amphibian metamorphosis. Triiodothyronine caused a sevenfold increase in translatable albumin mRNA and a threefold increase in translatable mRNA for the 23,000 dalton protein. These increases are consistent with a nuclear initiated mechanism for thyroid hormone action during amphibian metamorphosis.