bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lethal factors and enzymes in the secretion from Duvernoy's gland of three colubrid snakes
Authors: Rosenberg Herbert I. , Bdolah Avner , Kochva Elazar 
Published: June 2005

AbstractSecretion from Duvernoy's gland of the colubrid snakes Malpolon, Spalerosophis, and Thamnophis was obtained by pilocarpine stimulation and tested for lethality and selected enzymatic activities. Pools of secretion from Malpolon and Spalerosophis were fractionated by gel filtration, and several major active fractions were examined. The secretion from Malpolon had an LD50 of 6.5 μg/gm in mice; two lethal fractions with LD50's of 2.75 μg/gm and 4.5 μg/gm were isolated. One of these fractions appears to be a basic phospholipase A with a molecular weight of about 17,000. Spalerosophis had a secretion with an LD50 of 2.75 μg/gm in mice; one main lethal fraction with an LD50 of 2.5 μg/gm was isolated. Secretion from Thamnophis had an LD50 of 33.3 μg/gm; it was not fractionated owing to a paucity of material.At least two of the snake species examined have toxic secretions that may be important during feeding by killing or weakening and helping to subdue the struggling prey.
Redox regulation of caffeine contractures
Authors: Gábriel M. , Puppi A. , Szabó I. T. , Dely M. 
Published: June 2005

AbstractThe amplitude of caffeine contractures, tissue redox‐state potential, and electrical activity were simultaneously measured in the sartorius muscle of the frog, Rana esculenta following oxidant (methylene blue) and reductant (ascorbate, hydroquinone) treatments.Pretreatment with oxidant, in parallel with the increment of redox‐state potential, increased, while pretreatment with reductant, in parallel with the decrement of redox‐state potential, decreased significantly the amplitudes of caffeine contractures. The electrical activity, registered simultaneously, was not changed significantly.The mechanism of action of caffeine contractures is related to the increase of cytoplasmic Ca2+, and the results indicate that the actual redox‐state potential level, as one of the determinants of the internal milieu, is also a regulatory factor in relation to the excitation‐contraction coupling.
Effects of changes in hydrostatic pressure on Na transport in gammarid amphipods from Lake Baikal
Authors: Roer R. D. , Bekman M. Y. , Shelton M. G. , Brauer R. W. , Shvetzov S. G. 
Published: June 2005

AbstractA 60–140‐atm change in the hydrostatic pressure causes fresh water gammarid amphipods from Lake Baikal to lose Na+ to the medium. This effect occurs whether the change is an increase in pressure for shallow species or a decrease in pressure for deep species. The pressure effect is predominantly upon unidirectional influx. A pressure‐induced change in the dynamic fluidity of the membrane is suggested as a possible mode of action.
Nerve growth factor induces neural differentiation in undifferentiated cells of early chick embryos
Authors: Lee Hsin‐Yi , Nagele Robert G. , Roisen Fred J. 
Published: June 2005

AbstractNerve growth factor (NGF) induced differentiation in postnodal pieces (PNPs) of stage 4 chick embryos. This induction was highly selective for neural tissue; no other structures developed in the NGF‐treated PNPs. Furthermore, the number of PNPs showing neural differentiation was dependent on the concentration of NGF, but there was no correlation between the concentration of NGF (5–100 ng/ml) and extent of neuralization. The neural inducing capacity of NGF could be abolished by anti‐NGF antibody. NGF‐induced neural differentation was accompanied by elevated intracellular levels of cyclic AMP. Exogenous cyclic AMP (175 μg/ml) was able to stimulate neural differentiation but, unlike NGF, induced other structures (e.g., notochord and pulsatile tissue). Overall results suggest that (1) cells from chick embryos at developmental stages much earlier than previously thought are responsive to NGF and (2) NGF or a closely related substance may serve as a neural inducer in the chick embryo.
Differentiation of mouse ectopic germinal cells in intra‐ and perigonadal locations
Authors: Francavilla Sandro , Zamboni Luciano 
Published: June 2005

AbstractFour hundred and thirteen ectopic germinal cells in the testicular and extratesticular stroma and in the rete testis of mouse fetuses from day 13 of uterine development to term were studied together with 161 ectopic germinal cells in the rete ovarii and periovarian stroma of female fetuses at days 17 and 18 of intrauterine life. The morphology and the differentiation of these ectopic germinal cells were compared to those of germinal cells within seminiferous and ovigerous cords. While the ectopic germinal cells in the testis and in the rete testis followed patterns of differentiation identical with those in the seminiferous cords throughout the period included in the study, those in the extratesticular stroma behaved like entopic germinal cells only through day 17, since at days 18 and 19 many of them entered meiotic prophase just like XX germinal cells in the ovigerous cords. No differences were noted between ectopic and entopic ovarian germinal cells. The results of this study show that the factors responsible for the male differentiation of XY germinal cells are not limited to the seminiferous cords but operate throughout the testicular territory, and confirm that outside the testis, XY germinal cells differentiate as female; our study also corroborates the thesis that the differentiation of XX germinal cells is an autonomous and ubiquitous process.
Divergence in vascular actions of prostacyclin during vertebrate evolution
Authors: Piomelli D. , Pinto A. , Tota B. 
Published: June 2005

AbstractProstacyclin (PGI2) generation by teleost and elasmobranch fish vascular wall was detected, as 6‐keto‐PGF1α‐like immunoreactivity, in the incubation medium of ventral aorta rings from Anguilla anguilla, Conger conger and Scyliorhinus stellaris. The average yields after 15 min incubation were the following (ng of 6‐keto‐PGF1α‐like/g of wet tissue): A. anguilla =116.8 ±30; C. conger = 7.50; S. stellaris = 58.0 ± 10.Accordingly, the vascular responses to synthetic PGI2 were examined on the isolated and saline‐perfused head of four teleost (A. anguilla, C. conger, S corpaena porcus and Solea solea) and two elasmobranch (S. stellaris and Torpedo marmorata) species. In teleosts, PGI2 gave a dose‐related increase in overall gill vascular resistance, unaffected by indomethacin, phenoxybenzamine and phentolamine pretreatment or by previous decerebration of the animal. Conversely, in elasmobranchs PGI2 elicited a diphasic response, characterized by a transient, not dose‐related constriction, followed by a longer lasting and dosedependent dilation.The effects of PGI2 on isolated branchial arch (in A. anguilla, C. conger and S. stellaris) and ventral aorta strips (in C. conger and S. stellaris) were also examined. Both preparations shared the same responsivity of the head in toto, confirming the divergence observed in this respect between teleosts and elasmobranchs. The reactivity of teleost branchial vessels to this autacoid appears to be unique among the other vertebrates examined thus far.
Blocks to polyspermy in Chaetopterus
Authors: Eckberg William R. , Anderson Winston A. 
Published: June 2005

AbstractBlocks to polyspermy may act either at the level of the egg plasma membrane to prevent gamete fusion or at the level of egg surface coats to prevent gamete attachment. The present study was undertaken to determine what type(s) of block(s) to polyspermy exist in Chaetopterus. The results showed the existence of both types. A rapid block acts at the plasma membrane level based on independence from detectable changes in the vitelline layer and is dependent on external sodium ions. A vitelline layer block had been predicted on morphological evidence and is supported here by demonstrating an increase in polyspermy following chemical disruption of the vitelline layer. However, the vitelline layer of the fertilized egg retained its ability to initiate the acrosome reaction in sperm and attach sperm which had undergone the acrosome reaction. The vitelline layer block resulted from the retraction of egg microvilli from the vitelline layer, and not from elevation of the vitelline layer per se. Thus the vitelline layer of the fertilized egg could be involved in preventing sperm penetration into the egg without being altered structurally or functionally.
Fat bodies and reproduction in female Anolis carolinensis
Authors: Greenberg Dorianne S. , Gist Daniel H. 
Published: June 2005

AbstractThe role of the fat body in supporting ovarian growth was studied in the lizard Anolis carolinensis. Environmental and social stimulation of ovarian growth in well‐fed animals was not accompanied by reductions in fat body weight or by increases in serum nonesterified fatty acid (NEFA) levels. Adiposectomy had no effect on serum NEFA, but did reduce hepatic glycogen compared to sham‐operated controls. Adiposectomized lizards receiving injections (either hormone or carrier) also had lower hepatic glycogen levels when compared to uninjected controls. Administration of estradiol to ovariectomized lizards was effective in increasing serum levels of NEFAs, but had little effect on fat body weights. Follicle‐stimulating hormone (FSH) administration increased serum free fatty acid levels in sham‐operated lizards but was without effect in adiposectomized animals. It is concluded that the lipids contained in the lizard fat body are not preferentially utilized for reproduction and may not be used for that purpose if adequate energy is supplied from other sources.
Amino acid metabolism in euryhaline bivalves: Regulation of glycine accumulation in ribbed mussel gills
Authors: Ellis Lehman L. , Burcham James M. , Paynter Kennedy T. , Bishop Stephen H. 
Published: June 2005

AbstractGlycine levels in isolated ribbed mussel (Modiolus demissus) gill tissue increased slightly and decreased markedly when incubated at high and low salinities, respectively. Low levels of the enzymes involved in the biosynthesis of serine from triose phosphate intermediates, the serine hydroxy‐methyltransferase, and serine dehydrase were detected in gill tissue homogenates. Experiments using gill tissue incubated with (U‐14C)‐glycine and (U‐14C)‐serine indicated interconversion between serine and glycine and transfer of label to alanine, asparate, glutamate, CO2, organic acids, and protein. Glyoxylate was metabolized more slowly than glycine and was probably converted to glycine for catabolism. Studies using (1‐14C)‐glycine and (2‐14C)‐glycine with isolated gill tissue and mitochondria indicated that the mitochondrial glycine cleavage enzyme was the major route of glycine catabolism. Metabolic controls activating or inhibiting the glycine cleavage enzyme regulate tissue glycine accumulation and catabolism during hypersalinity or hyposalinity stress.
Repair of fractured lower jaws in the spotted salamander: Do amphibians form secondary cartilage?
Authors: Hall Brian K. , Hanken James 
Published: June 2005

AbstractSecondary cartilage forms on avian and mammalian dermal bones, both during normal ontogeny and during repair of fractures, but it has not been observed in any other vertebrate class. We fractured the left lower jaws of adult spotted salamanders, Ambystoma maculatum, to see whether secondary cartilage would form during fracture repair. It did not. Instead, periosteal hyperplasia produced a callus from which new dermal bone formed to bridge the fracture. Meckel's cartilage underwent superficial dissolution but showed a minimal chondrogenic response. A large callus cartilage did form, but it appeared to arise by metaplasia from connective tissue adjacent to the bone. Thus, the environment within the fracture is conducive to chondrogenesis but the periostea of the dermal bones either are not able to respond to that environment or are unable to synthesize cartilage‐specific products. Among recent vertebrates, the ability to form secondary cartilage is limited to birds and mammals and is not a primitive property of the periostea of dermal bones shared by “lower” vertebrate classes.
Effects of temperature upon capacitation of guinea pig spermatozoa
Authors: Fleming Alan D. , Kuehl Thomas J. 
Published: June 2005

AbstractSpermatogenesis in many mammalian species requires a temperature a few degrees below body core temperature. Upon ascent through the male tract and deposition in the female tract, the temperature of spermatozoa is increased to body core temperature. This report investigates the effects of temperatures above or below normal body core temperature, which is also the usual temperature of in vitro gamete incubations and fertilization, upon sperm acrosome reacting ability and fertility. Epididymal guinea pig spermatozoa were preincubated in a Ca2+‐free medium at temperatures of 15°C, 25°C, 37°C, or 44°C for increasing periods of time. At 15°C or 25°C, no or very few spermatozoa acquired the ability to acrosome react upon exposure to Ca2+ even after 18 hr of culture or warming up to 37°C. A known stimulator of acrosome‐reacting ability, lysophosphatidylcholine, was ineffective in promoting acrosome‐reacting ability in spermatozoa incubated at 15°C or 25°C. At 37°C the percentage of acrosome reaction increased steadily over time, reaching about 65% after 18 hr. At 44°C the time course of acquisition of acrosome‐reacting ability was greatly accelerated with a percentage at 2 hr comparable to that achieved at 37°C only after 18 hr of preincubation. This effect of incubation at 44°C could be reversed by cooling the spermatozoa to 37°C before they were exposed to Ca2+. Spermatozoa induced to undergo the acrosome reaction after preincubation at 44°C were fully capable of fertilizing intact guinea pig eggs. These results are discussed in relation to possible temperature‐dependent or ‐sensitive mechanisms that may be components of the capacitation process.
Occurrence and metabolism of D‐aspartate in the gutless bivalve Solemya reidi
Authors: Felbeck Horst 
Published: June 2005

AbstractHigh concentrations of free D‐aspartate were measured in foot tissue and symbiotic bacteria containing gill tissue of Solemya reidi. The enzyme D‐aspartate racemase could be shown to be present in the tissues but not D‐aspartate oxidase or glutamate oxaloacetate transaminase (D‐aspartate as substrate). Externally administered radiolabeled D‐aspartate is rapidly taken up and metabolized by the tissues of the animal. The possible role of D‐aspartate in the metabolism of S. reidi is discussed.
Repeated furrow formation from a single mitotic apparatus in cylindrical sand dollar eggs
Authors: Rappaport R. 
Published: June 2005

AbstractThe methods used previously to demonstrate the ability of a single mitotic apparatus to elicit multiple furrows involved considerable cell distortion and did not permit the investigator to control the positioning of the parts or to observe satisfactorily the early stages of furrow development. In this investigation, Echinarachnius parma eggs were confined in 82 μm i.d. transparent, silicone rubber‐walled capillaries, and the mitotic apparatus was moved by pushing the poles inward with 55‐μm‐diameter glass balls. When the mitotic apparatus was shifted immediately after the furrow first appeared, a new furrow appeared in the normal relation to the new position in 1–2 minutes. The same mitotic apparatus could elicit up to 13 furrows as it was shifted back and forth by alternately pushing in the poles. The previous furrow regressed as the new furrow developed. The operations protracted the furrow establishment period to as long as 24.5 minutes after establishment of the first furrow. The characteristics of furrow regression were related to the distance the mitotic apparatus was moved. It is unlikely that regression was caused either by stress imposed on the surface or the removal of the mitotic apparatus from the vicinity of the furrow.
Electrophysiology of identified neurosecretory and non‐neurosecretory cells in the cockroach pars intercerebralis
Authors: Krauthamer Victor 
Published: June 2005

AbstractTwo cell types can be distinguished with intracellular recording from the pars intercerebralis of the American cockroach (Periplaneta americana). The first type, which corresponds morphologically to the medial neurosecretory cell, always had spontaneously occurring, overshooting action potentials. These action potentials are probably endogenously produced. Tetrodotoxin experiments revealed that sodium is the dominant ion of the action potential. The action potentials are followed by a relatively long after‐hyperpolarization. The input resistance of these cells ranged from 120 to 390 MΩ. A mathematical model, based on cellular morphology and response to current pulses, revealed a membrane time constant of about 100 msec and an exonal:somatic conductance ratio of approximately 13. Area‐specific membrane resistance was estimated at 33 kΩ cm2. These cells also often had reversible and spontaneous inhibitory postsynaptic potentials. The second cell type, which is non‐neurosecretory, never produced spontaneous action potentials and rarely had synaptic potentials. Action potentials could be evoked by current injection into the cell body or by extracellular stimulation of their axons in the posteroventral portion of the the protocerebrum. These action potentials also depend on sodium ions. Their input resistance ranged from 16 to 35 MΩ. They had a membrane time constant of approximately 15 msec and an axonal:somatic conductance ratio of about 9. Their area specific membrane resistance was estimated at 14 kΩ cm2.
Morphology of identified neurosecretory and non‐neurosecretory cells in the cockroach pars intercerebralis
Authors: Krauthamer Victor 
Published: June 2005

AbstractElectrophysiologically identified cells of the cockroach pars intercerebralis (Periplaneta americana) were injected with the dye Lucifer Yellow for morphological examination and with horseradish peroxidase for ultrastructural marking. In addition to this, uninjected cells were also studied to elaborate the findings from the injected material. The two electrophysiologically distinct classes of cells (type I and type II) correspond to two distinct morphological and ultrastructural classes. Type I cells are the medial neurosecretory cells of the pars interecrebralis, which project their axons to the retrocerebral neuro‐hemal complex. Their cell bodies have a mean diameter of 17 μm, and they contain neurosecretory granules 200 nm in diameter. Arborizations emanate from the axon in the anterior part of the protocerebral neuropil. The type II cell bodies are larger (38 μm in diameter). Their axons project into the contralateral circumesophageal connective. These cells were usually multipolar, having somatic arborizations in the anterior portocerebral neuropil. The cell bodies contain vesicles 40 nm in diameter, numerous trophospongia, and a multi‐layered glial envelope.
Notochordal development as influenced by the insecticide dicrotophos (Bidrin)
Authors: Garrison James C. , Wyttenbach Charles R. 
Published: June 2005

AbstractWhite Leghorn chicken embryos were treated at different ages with the insecticide dicrotophos to determine the time period of maximum effect upon notochordal development. Doses of insecticide ranging from 250 μg to 2.0 mg were injected into eggs at 8, 16, 24, 32, 40, 48, 72, or 96 hr of incubation and the eggs allowed to incubate for an additional 48 hr. Dicrotophos treatment caused dorsoventral and lateral folding of the notochord, with the cervical region being most severely affected. Although there was no apparent difference in dose responsiveness at any one age, there was an obvious age relationship. Notochordal responsiveness, expressed as both the number and severity of folds, was low among the 8‐ and 16‐hr treated embryos, increased to a maximum in the 48‐hr treatment group, and then declined among the older embryos. The time of maximum effect correlates closely with the time of sheath deposition and vacuolization of the notochord, but not to initial formation of the notochord from the mesoblast or later extracellular matrix production by sclerotome cells. It is proposed that dicrotophos interferes with some aspect of sheath formation. The pressure exerted by the vacuolization upon a structurally weakened sheath is thought to cause the observed folding.
Is there a limit on in situ, genomic replication in Drosophila?
Authors: Butterworth F. M. , Rasch E. M. , Johnson M. B. 
Published: June 2005

AbstractThe number of genomic replications of four separate tissues was determined in Drosophila melanogaster by summing the total number of nuclei and the maximum amount of DNA per nucleus in each tissue. It was found that for a given tissue the total number of nuclei was generally inversely proportional to the maximum amount of DNA per nucleus. In addition the sum of the number of divisions giving rise to the nuclei and the number of DNA replications occurring in the nucleus in each tissue never exceeded 20.
Regrowth of amputated velvet antlers with and without innervation
Authors: Suttie J. M. , Fennessy P. F. 
Published: June 2005

AbstractThe influence of removing portions of the growing antler of yearling red deer stags on subsequent regeneration of the antler in the same season was studied. The influence of the innervation of the antler on such regeneration was the subject of a further study. When the top 0.5–1 cm was removed from antlers 9–17 cm long, growth was slightly reduced in that season. When the antler/pedicle length was reduced to 6–10 cm in antlers 16–38 cm long, branched antlers regrew in 11 out of 13 cases provided the amputation was carried out early in the growing season, i.e., before mid‐December. Denervated antlers were shorter, lighter, and of different shape compared with controls, but they were of similar density. Denervation was confirmed histologically. Cleaning of velvet and casting of antlers following castration were unaffected by denervation. It would appear that although nerves affect the size and shape of the antler, they are not essential to the actual control of antler growth and regeneration.
Necessity of an adequate nerve supply for regeneration of the amputated pectoral fin in the teleost Fundulus
Authors: Geraudie Jacqueline , Singer Marcus 
Published: June 2005

AbstractThe present work deals with the determination of the threshold of nerve fibers per unit of amputation surface necessary for regeneration of the pectoral fins of a teleost, Fundulus. Partial denervation of the amputated pectoral fins, i.e., resection of one or two of the three nerves of the brachial (= pectoral) plexus revealed that the presence of a single one allows the amputated fin to regenerate. From these data and others obtained previously, it is concluded that the nervous requirements for a teleost fin to regenerate are similar or slightly lower than those for tetrapods, for example in the newt, which are capable of appendage regeneration.
Sex determination in Hydra: Roles of germ cells (interstitial cells) and somatic cells
Authors: Campbell Richard D. 
Published: June 2005

AbstractGerm cells were exchanged between male and female hydra to determine whether the germ cells or the somatic tissues determine the phenotypic sex of the polyp. Interstitial cells, the precursors of gametes, were removed from male and female Hydra oligactis by gamma irradiation. The resulting polyps, termed “epithelial hydra,” possessed the characteristic morphology of H. oligactis, and could reproduce by budding but could not produce gametes. When these epithelial hydra were repopulated with interstitial cells from normal hydra of the same or opposite sex, their sexual phenotypes were those of the interstitial cell donors. These results indicate that the germ cells, rather than somatic cells, determine the phenotypic sex of hydra.