bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sensitivity of hemoglobins to intracellular effectors: Primitive and derived features
Authors: Scholnick David A. , Mangum Charlotte P. 
Published: June 2005

AbstractThe sensitivity of hemoglobin‐O2 binding to urea and Cl−, effectors in higher vertebrates and also blood constituents that vary with salinity in elasmobranchs, was examined in the highly euryhaline cownose ray Rhinoptera bonasus. The response was compared with that in a closely related stenohaline species, as well as several other elasmobranchs, teleosts, and simpler hemoglobin‐containing animals. Although the O2 binding of R. bonasus red blood cells and stripped hemoglobin is not sensitive to urea, trimethylamine oxide, or Cl−, neither is the hemoglobin of the stenohaline butterfly ray. Cl− lowers O2 affinity of the hemoglobins of three species of stenohaline sharks; urea only slightly increases O2 affinity of one of these hemoglobins and another is insensitive. In contrast, the hemoglobins of two highly euryhaline teleosts are sensitive to urea as well as Cl−; urea raises and Cl− lowers O2 affinity. Thus, while urea insensitivity does appear to protect the respiratory properties of the O2 carrier in the elasmobranchs, Cl− sensitivity appears to be unrelated to changes in the blood. Since the red blood cells and/or hemoglobins of simpler animals such as annelids and molluscs are also insensitive to urea and Cl−, insensitivity in the elasmobranchs is more likely to represent a primitive, inherited feature than one specifically evolved along with their distinctive form of osmoregulation.The limited information available suggests that ATP lowers O2 affinity of the shark but not ray hemoglobins, which may reflect the origin of intracellular modulation within the elasmobranchs.
Proportioning of body regions in the planarian Dugesia tigrina as a function of the length: Width ratio of the regenerating fragment
Authors: Mead Robert W. 
Published: June 2005

AbstractRegeneration was examined in different regions of planaria (Dugesia tigrina) in order to determine the effect that the shape of a section exerts on proportion regulation during regeneration. Length: width ratios were used as an index of section shape and experiments utilized sections at which this ratio was below 1.0 Proportion regulation was evaluated by determining relative area of major body regions for normal and abnormal regenerates. Proportional area of body regions anterior to the pharynx increased with proportional decreases in the length: width ratio for all regenerates, but this increase was greater for regenerates that originated from segments anterior to the pharynx. Changes in proportional area of one anterior body region were closely correlated to changes in porportional area of other anterior body regions. The exact nature of these correlations varied as a function of originating segment. A hierarchy also exists in proportional head tissue between normal and abnormal regenerates as total relative head area of twoheaded regenerates was around three times that of normal planarians while regenerates with one large head and without a pharynx had a proportional head size that was less than that of two‐headed animals but more than twice that of normal planarians.
Toward an understanding of the epithelial requirement for osteogenesis in scleral mesenchyme of the embryonic chick
Authors: Pinto Cheryl B. , Hall Brian K. 
Published: June 2005

AbstractExplants of scleral tissue from chick embryos of H.H. stage 29–36 (6–10 days of incubation) were used to determine if the epithelial‐mesenchymal interaction which initiates scleral bone formation is cell contact, extracellular matrix, or diffusion mediated. Transfilter tissue recombinations, in which explanted interacting tissues are associated across interposing Nuclepore filters of various pore sizes and thicknesses, were performed with scleral mesenchyme and epithelium. When filters with pore sizes which would allow the passage of cell processes and diffusible substances were used, osteogenesis was initiated in the scleral mesenchyme. When cell processes were blocked with thicker filters or smaller pore sizes, bone formation still occurred, indicating that a diffusible substance mediates this tissue interaction. Further support for a diffusion‐mediated interaction came from transfilter experiments using dialysis membranes to discriminate the size of the molecule(s), and Millipore filters to determine the distance over which these molecules travel. These experiments revealed that the scleral epithelial diffusible factor has a molecular weight of between 3500 and 6000 daltons, and acts over distances between 150 and 300 μm.
Uniform myosin isoforms in the flight muscles of little brown bats, Myotis lucifugus
Authors: Hermanson John W. , LaFramboise William A. , Daood Monica J. 
Published: June 2005

AbstractThe present study used muscle histochemistry and polyacrylamide gel electrophoresis of native myosin and myosin heavy chains to establish a correlation, if any, between chiropteran histochemical fiber types and myosin isoform composition. Histochemical analysis of the primary flight muscle, the pectoralis profundus, documented the presence of a single histochemical fiber type, here termed Type II. Electrophoresis of native myosin isolated from pectoralis muscle yielded a single isoform that comigrated with the FM‐3 isoform of rat diaphragm. Heavy chain analysis of the Myotis pectoralis demonstrated a single heavy chain with comparable electrophoretic mobility to rat IIa myosin heavy chain. These data demonstrate unique histochemical and biochemicla homogeneity in the myosin composition of the pectoralis muscle of Myotis lucifugus. Thus this muscle is extremely specialized for flight at histochemical, morphologic, and molecular levels. These data contrast with the mixed myosin and histochemical fiber types found in other mammals, as well as in other muscles of Myotis lucifugus.
Monoclonal antibody specific to signet ring cells, the vanadocytes of the tunicate, Ascidia sydneiensis samea
Authors: Uyama Taro , Nishikata Takahito , Satoh Noriyuki , Michibata Hitoshi 
Published: June 2005

AbstractAscidians are known to accumulate vanadium in their blood cells and have six to nine different types of blood cells. Among these cells, the signet ring cell has been newly identified as the vanadocyte (vanadium‐containing blood cell). We have raised monoclonal antibodies specific to the signet ring cells of Ascidia sydneiensis samea for use in the identification of vanadocytes. A hybridoma cell line which secretes a monoclonal antibody specific to the signet ring cell has been established. Immunoblotting analysis showed that the antigen recognized by the antibody is a single polyptide of about 45 kDa. It appears that the monoclonal antibodies specific to the signet ring cells may be useful markers for studies for the process of differentiation of ascidian blood cells.
Testicular thymidine incorporation in the prawn Macrobrachium rosenbergii: Molt cycle variation and ecdysteroid effects in vitro
Authors: Sagi Amir , Karp Lee , Milner Yoram , Cohen Dan , Kuris Armand M. , Chang Ernest S. 
Published: June 2005

AbstractWhile molting and reproduction in female crustaceans are often known to be coupled processes, the explicit nature of this coupling has not been studied in males. We examined the relationship between molting and spermatogenesis in 2 morphotypes of the freshwater prawn, Macrobrachium rosenbergii. These morphotypes were the rarely molting, dominant, blue‐claw male and the frequently molting, subdominant, orange‐claw male. Testes from the 2 morphotypes were dissected and cultured in vitro. The rate of [3H]‐thymidine incorporation (as a measure of DNA synthesis) was recorded. Autoradiography was performed with histological sections of the cultured tissue.A strong correlation between the incorporation rate and the molt stage was found. The blue‐claw males were intermolt stage C4 and the testicular [3H]‐thymidine incorporation rate was relatively low. The incorporation rate in premolt orange‐claw males was at least three times higher than in these results: heavy silver grain precipitation was observed on top of the spermatogenic zone in the testicular sections taken from premolt orange‐claw males.The correlation between DNA synthesis in the testes and the molt stage suggested that ecdysteroids either directly or indirectly participate in the regulation of spermatogenesis. We observed that 20‐hydroxyecdysone did indeed have a direct effect on DNA synthesis in cultured testis. Addition of 2.6 × 10−6M 20‐hydroxyecdysone increased [3H]‐thymidine incorporation into testes of premolt prawn by more than 50%.
Induction of deer antlers by transplanted periosteum: III. Orientation
Authors: Goss Richard J. 
Published: June 2005

AbstractThe effects of rotating, inverting, or mincing grafts of presumptive pedicle/antler periostea have been investigated in young male fallow deer. When discs of frontal periosteum were rotated 180° and replaced onto their pedicle regions, half of the resultant antlers grew in reversed orientation, while the others gave rise to appendages of indeterminate polarity. Transplantation of periosteal discs upside down beneath scalp or foreleg skin induced antlers of normal proximodistal orientation. Grafts inverted on top of intact pedicle protuberances with their anterior‐posterior and medial‐lateral axes in register produced antlers of normal lengths but with more points than in controls. If the antlerogenic periosteum is minced and scrambled before transplantation back onto the pedicle region, it is capable of producing an organized antler. It is concluded that the histogenesis of pedicle and antler resides in the frontal periosteum, and that the anterior‐posterior axis of antler orientation is determined by this tissue. The proximodistal axis of elongation is established in relation to the overlying skin. Other morphogenetic influences as yet to be identified contribute to the normalization of antler size and shape in the prospective sites of antlerogenesis on the head.
Egg capsule sheath of Loligo opalescens Berry: Structure and association with bacteria
Authors: Biggs James , Epel David 
Published: June 2005

AbstractThe sheath forming the outer layer of the egg capsule of the squid Loligo opalescens is an acellular matrix 1–2 mm thick which contains approximately 100 striations parallel to the capsule surface. Throughout this matrix is suspended a dense culture of bacteria arranged in one to five layers. The probable source of these bacteria is the accessory nidamental gland.
The role of the legs in the lateral giant fibre escape of the crayfish Cherax destructor (Crustacea: Decapoda: Astacura)
Authors: Davey Natalie , Macmillan David L. 
Published: June 2005

AbstractIt is known that leg positioning is important for reducing drag during escape mediated by the medial giant (MG) axon of the crayfish (Cooke and Macmillian, '85). This report examines the question of whether the legs also have a role in escape mediated by the lateral giant (LG) neuron. The trajectory and the dynamics of the lateral giant (LG) escape behaviour of the crayfish Cherax destructor were analyzed using high speed cinematographic techniques. The LG escape flip was found to be stereotyped for each particular animal but rested animals produce their own characteristic trajectories. We tested to see if denervation of the legs would alter the escape trajectory. Interference with the articulating membrane at the base of the legs alters escape performance and a new set of displacement curves characteristic of each animal is produced. This is the outcome whether or not the nerves are severed. Electrophysiological recordings confirmed earlier latency measurements (Cooke, '85) and indicate that the efferent signals to the legs evoked by LG activation arrive too late to position them to influence the escape trajectory. We suggest that operations on the articulating membrane produce their effects by altering the starting position of the legs. We provide some preliminary evidence that supports this hypothesis.
Branchial and branchiostegite carbonic anhydrase in decapod crustaceans: The aquatic to terrestrial transition
Authors: Henry Raymond P. 
Published: June 2005

AbstractCarbonic anhydrase (CA) activity was measured in the gills, branchiostegite, and cuticle of 5 species of decapod crustaceans displaying fully aquatic, semi‐terrestrial, and fully terrestrial lifestyles. Density‐gradient and differential ultracentrifugation were used to separate 2 subcellular fractions from these tissues, basal‐lateral membranes, and cytoplasm, in which CA activity was determined. Callinectes sapidus, a euryhaline aquatic species, had high levels of CA activity in both the cytoplasmic and membrane fractions of the gills. These pools of CA are believed to function in ion transport and CO2 excretion, respectively. The branchiostegite and cuticle, which do not play an apparent role in either process in the blue crab, possess much lower levels of CA activity in both fractions. In contrast, a stenohaline, stenothermal species, Chaceon fenneri, which has a low metabolic rate, has low levels of CA activity in the cytoplasm and membrane fractions of the gills. As decapod crustaceans invade the terrestrial habitat and make the transition to breathing air, gill surface area is reduced and the branchiostegite develops into a primitive lung. In Cardisoma guanhumi, a semi‐terrestrial crab, branchiostegal tissue has very little CA activity in either fraction, and enzyme activity is not different from that in the general cuticle; the gills still possess the bulk of CA activity in the animal. In fully terrestrial species (Gecarcinus lateralis and Birgus latro), however, the membrane fraction of the branchiostegite has the same level of CA activity as that of the gills, regardless of species, while CA in the cuticle remains low. It appears, according to the distribution of membrane‐associated CA, that while the gills of aquatic crustaceans are the primary route of CO2 excretion, the branchiostegite can supplement branchial CO2 elimination in terrestrial species.
Daily variations in plasma hormone concentrations during the semilunar spawning cycle of the gulf killifish, Fundulus grandis
Authors: Emata Arnil C. , Meier Albert H. , Hsiao Shyh‐Min 
Published: June 2005

AbstractMale and female gulf killifish, Fundulus grandis, were kept in large cages submerged in their natural habitat in the Gulf of Mexico. Gonadosomatic indices (GSI: 100 × gonad weight/body weight) and blood samples were obtained from male and female fish every 4 hours (beginning at 1600) throughout a day on 3 separate days of the semilunar cycle: at the GSI and spawning peak (July 27–28), at midcycle (August 2–3), and on a day prior to the probable spawning peak (August 9–10). Blood samples of females were assayed for cortisol, estradiol‐17β (E2), progesterone, testosterone, thyroxine (T4), and triiodothyronine (T3). The daily rhythms of hormones at each of the three days during the cycle differed markedly from one another. At the spawning peak, E2 and T3 peaks occurred at 1200, testosterone and progesterone peaks were found at 2400 and the GSI and cortisol peaks were at 0400. The GSI decreased sharply at 0800 indicating a period of probable spawning. At midcycle, most hormone levels were low throughout the day and the amplitudes of the hormone rhythms were suppressed. One day prior to the spawning peak, testosterone and progesterone variations (peaks at 2400) were similiar to those found on the day of the first semilunar GSI and spawning peaks. Daily variations of other hormones, especially E2, were prominent on the day prior to peak spawning but different from those found on the day of peak GSI/spawning. In males, plasma concentrations of cortisol, testosterone, T3 and T4 also underwent daily variations that differed from one another on the 3 days of the cycle. The results clearly demonstrate that there are dramatic changes in the daily variations of plasma hormone concentrations during the semilunar spwning cycle.
Proliferative activity of somatic cells during gonadal development in the Japanese pond frog, Rana nigromaculata
Authors: Tanimura Akihiko , Iwasawa Hisaaki 
Published: June 2005

AbstractProliferative activities of gonadal somatic cells were examined autoradiographically during gonadal development in Rana nigromaculata. Both the germinal epithelium and the sexual cord appeared to be of coelomic epithelial origin, as indicated ultrastructurally by the observation that the 2 regions were covered with a common basal lamina. Cell‐proliferative activity was higher in the sexual cord than in the germinal epithelium at stage 29, suggesting that topographically specific active proliferation of coelomic epithelial cells contributed to the formation of the sexual cord. In the course of testicular development, high proliferative activity of the sexual cord was recognized until stage 32 (just after gonadal sex differentiation). At stage 43 (during metamorphosis), higher proliferative activity was noted in the germinal epithelium than in the sexual cord, and the germinal epithelium differentiated into seminiferous cords. There were no differences in proliferative activity between the germinal epithelium and sexual cord at stages 32 and 34 in the ovaries. At stage 43, there was higher proliferative activity in the germinal epithelium than in the sexual cord, and the germinal epithelium differentiated into follicular cells. These results suggest that both seminiferous cords and follicular cells are derived from germinal epithelium and that both pass through similar processes of development.
Zinc‐protein from rat prostate fluid binds epididymal spermatozoa
Authors: Sansone G. , Abrescia P. 
Published: June 2005

AbstractThe detection and the isolation of a zinc‐protein from the secretion of the rat dorsolateral prostate is described. The purification procedure, based on gel filtration and cationic exchange chromatography, allowed to separate a minor protein (Mr ≈︁ 66,000) from free zinc ions and other secretory components. Two zinc ions were estimated to be associated with one molecule of isolated protein. The zinc‐protein was labelled with 125I and then incubated at 37°C with spermatozoa from rat epididymal cauda. Time‐dependent in vitro binding of the radioactive protein to sperm cells was demonstrated. This binding was not affected by the presence of proteins from the seminal vesicle during the incubation, while it was blocked in the presence of an excess of unlabelled zinc‐protein. After binding, the labelled spermatozoa were treated with a buffer containing 0.5% sodium deoxycholate and 40 mM EDTA; only very small amounts of label were removed from the cells, thus suggesting that the zinc‐proteins were kept on the plasma membrane by interactions which do not involve merely hydrophobic bonds.
Metabolic consequences of exercise in organs of rainbow trout
Authors: Storey Kenneth B. 
Published: June 2005

AbstractThe effects of exhaustive swimming on a number of metabolic parameters were assessed in six organs of rainbow trout (Oncorhynchus mykiss). Glycogen phosphorylase was activated in four organs (liver, gill, heart, and white skeletal muscle), the largest increases in phosphorylase a activity being 5.3‐ and 6‐fold in liver and white muscle, respectively. Exhausted fish showed elevated lactate levels in all organs except brain with absolute increases of about 12 μmol/g wet weight in white and red skeletal muscles but only about 1 μmol/g in internal organs. ATP content dropped dramatically in skeletal muscles after exercise but remained constant in other organs. Fructose‐2,6‐bisphosphate levels rose in liver and brain but dropped in gill and heart during exercise. Kinetic properties of trout liver 6‐phosphofructo‐1‐kinase and pyruvate kinase were assessed in control versus exhausted fish. Neither enzyme showed changes in substrate affinities, ion cofactor affinities, or sensitivities to metabolite inhibitors or activators as a result of exercise, giving evidence that these liver enzymes (unlike glycogen phosphorylase) were not modified by reversible protein phosphorylation in response to muscle exercise. Exhaustive exercise also resulted in major changes in the levels of various free amino acids in trout organs. Alanine content rose by 9–11 μmol/g in heart, gill, and brain. Glycine increased by 12 μmol/g in white muscle and by 0.4–2 μmol/g in liver, heart, and gill. Several organs also showed significant changes in glutamate and glutamine contents and free histidine content increased in others, most notably by 2.8 μmol/g in white muscle. Organ‐specific patterns of response to the exercise stress are indicated.
Calcium regulation of epidermal cell differentiation in the frog Xenopus laevis
Authors: Shimizu‐Nishikawa Keiko , Miller Leo 
Published: June 2005

AbstractAdult frogs have a stratified epidermis with a keratinized stratum corneum. Since the extracellular calcium concentration is known to regulate differentiation of mammalian epidermal cells in vitro, we studied the effects of calcium on the terminal differentiation of frog epidermal cells. Exposure of the epidermal cells to a high concentration of calcium (> 0.2 mM) induced cornification and the synthesis of a 51 Kd acidic keratin. These data are very similar to the results from mammalian epidermal cell cultures, suggesting that the mechanism of terminal differentiation is conserved throughout the evolution of terrestrial vertebrates.
Timed daily injections of neurotransmitter precursors alter the gonad and body weights of spotted munia, Lonchura punctulata, maintained under short daily photoperiods
Authors: Chaturvedi C. M. , Prasad S. K. 
Published: June 2005

AbstractThe present study was designed to examine the role of circadian organization in the control of seasonality in the seasonally breeding spotted munia, Lonchura punctulata, which does not utilize photoperiod to time its reproduction under natural day‐length conditions.Daily injections of L‐dihydroxyphenylalanine (L‐DOPA, precursor of dopamine) given 12 hr and 8 hr after administration of 5‐hydroxytryptophan (5‐HTP, precursor of serotonin) alter the gonadal and body‐weight responses of the spotted munia, when it is maintained under short‐day conditions (LD 6:18). The 12‐hr interval was stimulatory and the 8‐hr interval was inhibitory for both gonadal and body‐weight responses while other intervals (0, 4, and 16 hr) had no effect. A 20‐hr interval was stimulatory only for gonadal growth and had no effect on body weight.These findings support the suggestion that the endogenous seasonal mechanism is determined by circadian organization (i.e., by changes in the phase relationships of two neural oscillations and their many other circadian expressions). The results also indicate that interaction between these two systems does not produce any pharmacological effect but actually affects the seasonality of the birds, as indicated by the different gonadal and metabolic conditions that followed differently timed daily injections of drugs that influence serotonergic and dopaminergic activities. Furthermore, the mechanism of regulation of seasonality seems to be similar in species that do and do not utilize day length as the primary regulator with which to time their seasonal reproductive and metabolic cycles.