bluuebunny/crossref_metadata_2025_split huggingface dataset:
Self‐organizational capacity of distally transplanted limb regeneration blastemas in larval salamanders
Authors: Stocum David L. , Melton Douglas A. 
Published: June 2005

AbstractPrevious autografting and homografting experiments (Iten and Bryant, '75; Stocum, '75b) showed that, when progressively later stages of upper arm blastemas were transplanted to either the distal radio‐ulna or the wrist, surviving grafts of each stage formed wrist and hand parts in 100% of the cases. However, the earliest stages transplanted formed the humerus and radio‐ulna at a low frequency, with an increase in this frequency when later stages were transplanted. These results can be interpreted in two ways: (1) The proximal‐distal organization of the blastema is stable at the earliest stages with the low frequency of humeral and radio‐ulnar formation being attributable to artifacts introduced by surgical trauma, artifacts which would not have as much effect on later stages; (2) The proximal‐distal organization of the early blastema is initially labile and can interact with the stump to conform to the level of transplantation. This lability would decrease in later stages. The present study describes the results of new experiments which argue against the latter alternative. In addition, differences between autograft and homograft development are described which could be attributable to an immune response directed at homografts.
A scanning electron microscopic and X‐ray microanalytic study of cell surface material during amphibian neurulation
Authors: Rice Robert W. , Moran Denis J. 
Published: June 2005

AbstractTreatment with lanthanum (La3+) after fixation in phosphate (PO4−3)‐buffered glutaraldehyde results in the deposition of a cell surface material (CSM) primarily on the developing urodele amphibian neural axis. X‐ray probe microanalysis indicates that calcium (CA2+) levels are considerably higher in the neural fold region. La3+ displaces Ca2+ from negatively‐charged moieties on biological membranes. Once bound, La3+ likely interacts with residual phosphate(s) resulting in deposition of CSM. Elemental X‐ray microanalysis shows CSM contains mostly lanthanum and phosphorus. The high level of regional La3+ binding is correlated with inherently greater Ca2+ levels in the developing neural axis.
Genetic and experimental studies on three associated mutant genes in the Mexican axolotl: st (for stasis), mi (for microphthalmic) and h (for hand lethal),
Authors: Humphrey R. R. , Chung Hae‐Moon 
Published: June 2005

AbstractThree mutant genes, st, mi, and h, were discovered in an axolotl male received from Mexico City. All three are recessive to their normal alleles, and appear to segregate independently.Larvae homozygous for st (for stasis) suffer blockage of the circulation at hatching or shortly after, and the majority soon die; any surviving live only a few weeks at most. The mi/mi (microphthalmic) can be identified at the feeding stage. None survives more than a few days. The h/h (hand lethals) live until the digits have appeared on the forelimb. They may then be recognized by the thumb‐like orientation of digit 1.Transplants from st/st embryos into normal produce normal structures which persist indefinitely. Those from mi/mi and h/h donors do not survive. The structures (forelimb, gills) derived from h/h donors grow for a relatively long time, and their final death and degeneration result in defects leading to death of most of the recipients.Parabiosis is of no benefit to st/st or h/h mutants and leads to the death of the normal twin; mi/mi mutants undergo a gradual absorption by the normal twin.
Timing of sperm penetration, pronuclear formation, pronuclear DNA synthesis, and first cleavage in naturally ovulated mouse eggs
Authors: Krishna Maryala , Generoso Walderico M. 
Published: June 2005

AbstractTiming of development of naturally ovulated mouse eggs from sperm penetration to first cleavage, including that of DNA synthesis, was established. In an attempt to limit variability, partial synchronization of ovulation was accomplished by shortening the length of the dark period to five hours, and partial synchronization of sperm entry was attempted by mating the females soon after the ovulated eggs reached the ampulla and by limiting the period at which mating could occur to only 20 minutes.Evidence of sperm penetration (presence of one or more sperm in perivitelline space or inside the vitellus) was found beginning 1.75 hours after the end of the mating period. Pronuclei were formed three to four hours after sperm entry. Pronuclear DNA synthesis began about eight hours postmating, 3.25 to 4.5 hours after pronuclear formation, or about 6.25 to 8.5 hours after sperm entry; it was completed in almost all zygotes by 16 hours postmating. The first completed cleavage division was found 17 to 18 hours postmating, and almost all eggs had cleaved by 20 hours.
Development of sodium regulation and de novo synthesis of Na+K‐activated ATPase in larval brine shrimp, Artemia salina
Authors: Conte F. P. , Droukas P. C. , Ewing R. D. 
Published: June 2005

AbstractThe development of brine shrimp embryos, A. salina, incubated in media of increasing salinity is delayed as evidenced by decreased emergence and lengthening of the time for excystment. Prehydration of cysts at low temperature (3°C) for four to ten hours in distilled water eliminates asynchrony of the population in regard to emergence and hatching times. Internal concentration glycerol, which controls the rate of hydration of the cyst stage, is markedly affected by external salinity. Water balance in the cyst stage is maintained via the trehalose‐glycerol mechanism which generates a simple passive diffusional gradient across the chitinous shell allowing water to pass. Non‐gaseous solutes, such as sodium and glycerol, do not pass through the chitin‐membrane barrier. Rupturing the shell by emergence initiates the onset of the prenaupliar stage; it is accompanied by the appearance of large amounts of free glycerol in the external media, decreasing levels of internal glycerol, increased concentrations of internal sodium and the first detectable levels of the cationic transport enzyme, Na + K‐ATPase. Continual loss of free glycerol through the cellular and hatching membranes causes the excysting embryo to convert from a trehalose‐glycerol mechanism to a sodium‐mediated transport system in order to maintain larval water balance. Ontogeny of the sodium regulating mechanism requires formation of Na + K‐ATPase. The production of new Na + K‐ATPase, as evidenced by incorporation of 14C‐amino acids into polypeptide subunits and density‐gradient centrifugation of radioactive membrane vesicles rich in Na + K‐ATPase, may play an important role and, if so, it appears to be initiated between E‐1 and E‐2 stages.
Periodic respiratory and circulatory performance in the red rock crab Cancer productus
Authors: McMahon B. R. , Wilkens J. L. 
Published: June 2005

AbstractPeriods of simultaneous arrest in both cardiac and scaphognathite (ventilatory) pumps of up to 20 minutes duration occur spontaneously and repetitively in resting restrained Cancer productus. Measurement of cardiac and scaphognathite beat frequencies, ventilation volume, oxygen uptake and circulating blood oxygen tensions indicate that oxygen exchange is more effective in this species than has previously been reported for other brachyuran decapods and compensation for long pauses involves only short periods of moderate hyperventilation and enhanced oxygen uptake. The initiation, importance and control of pausing behaviour is discussed. During periods of repetitive pausing a stereotyped pattern of heart and scaphognathite responses occurs. The pattern is easily modified by such factors as activity and oxygen availability. This study suggests that higher neural control centers coordinate the beating of heart and scaphognathites thus allowing regulation of gas transport and exchange.
Endocrine control of vitellogenesis in Drosophila melanogaster: Effects of the brain and corpus allatum
Authors: Handler Alfred M. , Postlethwait John H. 
Published: June 2005

AbstractThe endocrine control of yolk deposition in Drosophila melanogaster was studied by ligation and transplantation techniques. Endocrine events associated with the initiation of vitellogenesis were found to be synchronized with eclosion rather than the completion of adult development. Decapitation experiments showed that a cephalic event occurring at about the time of eclosion is necessary for each animal to initiate vitellogenesis. The morphogenetic effect of the head could be replaced by a juvenile hormone analog (JHA).In addition to the cephalic event, a thoracic factor is required for each follicle to initiate vitellogenesis, since preparation of isolated abdomens before 16 hours after eclosion prevented vitellogenesis. In abdomens isolated after this time, no early vitellogenic stages were formed. The suppression of vitellogenesis in isolated abdomens was reversed by implanting corpora allata or by treating these preparations with JHA, but not by implanting corpora cardiaca. Ovaries that were artificially induced to mature by treating isolated abdomens with JHA still displayed the normal complement of ovarian proteins after electrophoresis in polyacrylamide gels.These results show that a circadian clock triggers vitellogenesis via a cephalic signal at eclosion, which in turn triggers events in the thorax or abdomen. The cephalic signal can be superseded by juvenile hormone, whose presence is necessary for each follicle to become vitellogenic.
On the diversity of sperm histones in the vertebrates. III. Electrophoretic variability of testis‐specific histone patterns in Anura contrasts with relative constancy in Squamata
Authors: Kasinsky H. E. , Huang S. Y. , Kwauk S. , Mann M. , Sweeney M. A. J. , Yee B. 
Published: June 2005

AbstractA starch gel electrophoretic survey of testis‐specific histones in frogs, snakes and lizards reveals a multiple banded pattern in most of these vertebrates whether the proteins are extracted from the testis cell suspension of a single animal or from chromatin pooled from the testes of several animals. Hence, the multiple banded pattern is probably typical for each individual in a particular species. When such testis‐specific histones of Anura are compared with those of Squamata, a notable difference emerges. Thus, the principal Xenopus, Bufo and Rana testicular proteins show entirely different patterns from each other upon starch gel electrophoresis while in Squamata, each of the species examined shows a similar 2‐banded pattern in the protamine region of the electrophoretogram. In the anurans Xenopus and Scaphiopus, the testis‐specific histone patterns are different even amongst several congeneric species. Although the present survey examines only a limited number of species, the electrophoretic data do point to the order Squamata as one place in vertebrate phylogeny where the diversity of testis‐specific histones in fish and amphibians appears to give way to a relative constancy of such proteins in reptiles. Such an evolutionary trend may be consistent with a modified version of Bloch's ('69) hypothesis that relates sperm histone variability to genetically based sex determination.
Disintegration of the vitelline coat during the hatching process in the frog
Authors: Yoshizaki Norio 
Published: June 2005

AbstractIn the frog, Rana japonica, the volume enclosed by the vitelline coat (VC) does not change during embryonic development up to stage 16 but increases during stages 17–18. During these latter stages, approximately one‐third of the VC material is lost as determined by its dry weight, proteins and neutral sugars. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis showed that two high molecular weight proteins disappear from the VC during stages 18–20. Electron microscopic observation of the VC revealed that the network of filament bundles which runs parallel to the egg surface disintegrates or diminishes during stages 17–20. Besides the VC, the innermost jelly layer (J1) becomes susceptible to UV irradiation at stage 18. All the changes observed in the present study prove that the partial disintegration of the VC and J1 by the hatching enzyme occurs during stages 17–20, three days before embryonic hatching.
Air‐breathing in a California sculpin
Authors: Wright W. G. , Raymond J. A. 
Published: June 2005

AbstractThe intertidal sculpin Clinocottus recalvus has been observed emerged and showing signs of air‐breathing near tidepools in a cave on the central California coast. In the laboratory the fish consumed oxygen at nearly equal rates in water and air, but release of carbon dioxide was retarded in air. The cause of emergence appeared to be low oxygen levels in the tidepools. This is the first report of air‐breathing in the sculpin family.
Interaction of immunoglobulin fragments with the mammalian sperm acrosome
Authors: Allen G. J. , Bourne F. J. 
Published: June 2005

AbstractA study was made of the interaction of immunoglobulins and immunoglobulin fragments from sera of rabbits and pigs with the acrosomes of ten species of mammalian spermatozoa to investigate previous reports of an interaction between normal serum and the acrosome. It was shown that this could be predominantly attributed to IgC, although there was weak staining due to IgM. Further, it was shown that IgG interacted through the Fc fragment, the Fab fragment causing only weak staining of homologous spermatozoa.
Transformation of amphibian xanthophores into melanophores in clonal culture
Authors: Ide Hiroyuki 
Published: June 2005

AbstractXanthophores isolated from bullfrog tadpoles were successfully cloned. The rapid disappearance of the yellow pigment‐containing organelles (pterinosomes) occurred in proliferating xanthophores and many black granules were newly synthesized in the cells. The granules were electronmicroscopically identified as melanin granules. These chromatophores showed melanin dispersion by the addition of the alkali‐treated ACTH. The findings suggest that xanthophores transform into melanophores in vitro.
Chick somite determination: The role of factors in young somites and the segmental plate
Authors: Packard David S. 
Published: June 2005

AbstractOne class of hypotheses proposed to explain the anterior to posterior sequence of chick somite formation envisions the movement of morphogenetic substances or processes along the segmental plate prior to somite formation. An effort was made to demonstrate any such phenomena in the region of somite formation by placing grafts that contained forming somites into the segmental plates of cultured host embryos. No somite‐inducing properties on the part of the grafts were detected. Host somite formation proceeded in a normal manner. In additional experiments, posterior portions of segmental plates were isolated from the more anterior parts of the segmental plate which might contain the hypothetical morphogenetic factors. It was found that anterior portions of the segmental plate representing as many as eight prospective somites could be removed without impairing the ability of the remaining posterior portion to form somites in vitro. It is concluded that other hypotheses of the type studied here are not likely to be useful and that the present data further strengthen the argument that the cells of the chick segmental plate present at any time between the 8‐ and 20‐somite stages of development are committed to form somites. In addition, the explant experiments described here indicate that a somite pattern representing about 11 prospective somites, becomes established in the segmental plate.
Urea levels in plasma and erythrocytes of the southern fiddler skate, Trygonorhina fasciata guanerius
Authors: Browning J. 
Published: June 2005

AbstractPlasma and erythrocyte esamples from Trygonorhina fasciata guanerius were analysed for urea content. The erythrocyte urea concentration is higher than plasma urea concentration. The difference in concentration is probably due to the presence of urea normally bound to protein within the erythrocyte. Erythrocyte urea concentrations followed environmentally induced changes in plasma urea concentrations. Naturally occurring plasma urea concentrations, exceeding 500 mMolar, are some of the highest recorded for an elasmobranch.
Allosteric modifiers of fish hemoglobins: In vitro and in vivo studies of the effect of ambient oxygen and pH on erythrocyte ATP concentrations
Authors: Greaney George S. , Powers Dennis A. 
Published: June 2005

AbstractFundulus heteroclitus decreases erythrocyte adenosine triphosphate and increases blood hematocrit when acclimated to hypoxic conditions. A defined medium has been developed which allows isolated F. heteroclitus erythrocytes to be maintained for several hours without an appreciable loss of cellular ATP. The effect of oxygen tension, pH and metabolic inhibitors on the cellular concentration of ATP of fish red cells has been investigated as an in vitro model to explain in vivo responses to environmental changes. The isolated red cells significantly decrease their ATP/Hb molar ratio when exposed either to anaerobiosis or metabolic inhibitors. It is concluded that the in vivo response is mediated at the red cell level via decreased oxidative phosphorylation in the presence of low environmental oxygen. The length of time necessary to elicit the response both in vivo and in vitro is also discussed.
Nuclear protein changes in the maternally and paternally derived chromatin at fertilization
Authors: Kunkle Mel , Longo Frank J. , Magun Bruce E. 
Published: June 2005

AbstractThe proteins which become associated with the paternally derived chromatin during fertilization may be instrumental in its activation and in the dramatic structural metamorphosis of the sperm nucleus during pronuclear development. Proteins associated with sperm and zygote nuclei and male and female pronuclei of fertilized sea urchin eggs were analysed by polyacrylamide gel electrophoresis in order to examine nuclear protein changes in the paternally and maternally derived chromatin following insemination. Results demonstrate major changes in both the solubility characteristics and polypeptide profiles of sperm nuclei upon insemination. Evidence is presented which indicates that at fertilization the paternally derived chromatin acquires proteins of molecular weights greater than 80,000 and a nuclear protein composition similar to that of the female pronucleus. The nuclear proteins associated with zygote nuclei were compared to those of combined male and female pronuclei and showed many similarities and some differences. Several polypeptides were present in zygote nuclei which were not observed in pronuclear extracts.
Regulation of the oxidative NADP‐enzyme tissue levels in Drosophila melanogaster. II. The biochemical basis of dietary carbohydrate and D‐glycerate modulation
Authors: Geer B. W. , Woodward C. G. , Marshall S. D. 
Published: June 2005

AbstractWhen cultured on a series of casein‐synthetic diets constituting a dietary sucrose gradient, the tissue levels of glucose‐6‐phosphate dehydrogenase (EC 1.1.1.49) and 6‐phosphogluconate dehydrogenase (EC 1.1.1.43) in the third instar larvae of Drosophila melanogaster paralleled the dietary sucrose concentration. The tissue level of malic enzyme (EC 1.1.1.40) was increased only by very high concentrations of dietary sucrose; whereas, the tissue level of NADP‐isocitrate dehydrogenase (EC 1.1.1.42) was negatively correlated with the dietary sucrose concentration. Dietary supplements convertible to the intermediates of the initial steps of glycolysis stimulated high tissue levels of glucose‐6‐phosphate dehydrogenase; D‐glycerate was the most effective inducer. Dietary sucrose increased the tissue concentrations of the intermediates of glycolysis that yield lipid substrate. As a result, lipid synthesis, pentose shunt activity and the tissue levels of the oxidative pentose shunt enzymes were elevated. In contrast, D‐glycerate increased the concentrations of the intermediates of the initial part of glycolysis and stimulated high tissue levels of the oxidative shunt enzymes without concurrent increases in pentose shunt activity or lipid synthesis. Thus, the activity of the pentose shunt is a function of lipid synthesis; whereas, the tissue levels of glucose‐6‐phosphate dehydrogenase and 6‐phosphogluconate dehydrogenase are dependent on the concentrations of one or more metabolites derived from the initial part of glycolysis.
Characteristics of resting ventilation and response to hypoxia, hypercapnia, and emersion in the blue crab Callinectes sapidus (Rathbun)
Authors: Batterton Carol V. , Cameron James N. 
Published: June 2005

AbstractVentilation volume was monitored in the blue crab Callinectes sapidus using an electromagnetic flow probe. The mean resting ventilation volume for a 200 g crab was 111 ± 78 ml. min−1, mean oxygen consumption was 62 ± 27 ml. kg−1. hr−1, and mean extraction efficiency was 53 ± 15%. Blue crabs continued to ventilate in air for at least eight hours at room temperature and were able to maintain oxygen consumption during exposure to air. The crabs did not change ventilation, oxygen consumption or extraction efficiency significantly in response to hypercapnia (7.5 or 15 torr Pco2), whether breathing air, fresh water, or sea water. Ventilation increased 37% at reduced oxygen tensions (24–65 torr), but since the extraction efficiency remained the same, oxygen consumption fell more sharply at lower O2 tensions. Pecularities of the ventilatory system, such as apnea, reversals, unilateral apnea or reversals, and variable phasing of the two scaphognathites were observed. Ventilation volume varied linearly with scaphognathite frequency and pressure differential; the scaphognathite stroke volume and gill sieve resistance appeared to be constant.
A comparison of amino acid accumulation during high salinity adaptation with anaerobic metabolism in the ribbed mussel, Modiolus demissus demissus
Authors: Baginski Richard M. , Pierce Sidney K. 
Published: June 2005

AbstractThe metabolic alterations leading to accumulation of amino acids during the initial stages of acclimation to high salinity and anaerobiosis appear to be different in Modiolus demissus demissus. First, the major metabolic event (activation of phosphenolpyruvate carboxykinase) does not appear to occur during acclimation to high salinity since increased incorporation of 14C‐bicarbonate into succinate of isolated gills occurred only in anaerobic treatment. Secondly, the cellular changes in concentrations of amino acids and succinate observed in isolated ventricles and gills after exposure to high salinity and anaerobiosis were not similar. Thirdly, during anaerobiosis the total amino‐acid pool remained constant largely because of decreased aspartic acid concentrations.Although different from the response to anaerobiosis, the mechanism of intracellular free amino acid accumulation during the initial stages of high salinity acclimation also depends on an alteration of intracellular metabolism. Thus, isolated ventricles exposed to salinity increases showed significantly lower levels of radioactivity in glycogen than ventricles maintained in low salinity. Similarly, radioactive glucose was selectively incorporated into the major osmotic solute (alanine) used initially during acclimation to high salinity.These results suggest that the intracellular free alanine accumulated during acclimation to high salinity is synthesized using glycogen as the carbon source.