bluuebunny/crossref_metadata_2025_split huggingface dataset:
Avian feather keratins: Molecular aspects of structural heterogeneity
Authors: Busch Neal E. , Brush Alan H. 
Published: June 2005

AbstractSolubilized SCM‐Keratins from feathers of a tern (Sterna hirundo) and turkey (Meleagris gallopavo) were fractionated by gel‐filtration and ion‐exchange chromatography. Tryptic peptide maps were prepared and amino‐acid compositions determined. Subsequent comparison indicated that within each species the FKM were closely related, but separate gene products. Interspecific comparison showed species specificity. The data were compared with the homologous FKM of other species and to amino‐acid composition data of the unfractionated SCM‐KM from other tissues.These results support the proposition that feather keratins represent a family of closely related gene products. The primary function of the multiplicity of structural elements is in the macro‐molecular organization of the tissue. The monomers can self‐associate to form both the filamentous structures and an intermolecular matrix. The FKM also provide tissue specific organizational information. The chemical composition and distribution of the different FKM presumably determines the unique morphological and functional aspects of the feathers.
Acute and chronic hypoxia in rats. 1. Effect on organismic respiration, mitochondrial protein mass in liver and succinic dehydrogenase activity in liver, kidney and heart
Authors: Pickett Cecil B. , Cascarano Joseph , Wilson Margaret A. 
Published: June 2005

AbstractThe objective of this investigation was to characterize organismic, organ and mitochondrial alterations in rats over the course of 27 days at 0.4 atm. In the adjustment phase (day 1 through 5) a significant decrease in systemic oxygen uptake and body weight (23% of pre‐altitude values) occurred. In the acclimating state (day 7 to 27) body weight was regained but oxygen consumption remained depressed. Hematocrit increased hyperbolically from 45% in 0‐day rats to 79% in 27‐day rats. Liver, kidney and heart weights and total organ protein paralleled the changes observed in body weight. Total organ succinic dehydrogenase activity showed a wave‐like oscillation for liver and kidney; activity was decreased in both organs by day 5, showed a transient but significant increase on days 16 through 18 and a return to diminished activity on day 27. Succinic dehydrogenase activity for heart became depressed in the adjustment phase but showed a stable level comparable to pre‐altitude values in the acclimating phase, days 7 through 27. Liver mitochondrial protein mass was unchanged from pre‐altitude values on days 5 and 27 even though succinic dehydrogenase activity was significantly depressed. Therefore, the changes in succinic dehydrogenase activity are not representative of altered mitochondrial mass but suggest that mitochondrial function was altered.
The developmental appearance of hexokinase and alcohol dehydrogenase in Xenopus laevis
Authors: Wesolowski Mary H. , Lyerla Timothy A. 
Published: June 2005

AbstractThe stages of appearance of hexokinase (HK; E.C. 2.7.1.1) and alcohol dehydrogenase (ADH; E.C. 1.1.1.1) in Xenopus laevis were studied using starch gel electrophoresis. The HK activity detected in this investigation is gut‐specific and appears at metamorphic climax (stage 63: Nieuwkoop and Faber, '67). Kinetic studies from crude homogenates tentatively identify this as a low Km HK type. ADH is first detected in larval stage 47 and is primarily liver‐specific. It is postulated that the observed electromorphic variation can be explained by assuming there are at least three ADH loci in this species, but the products of only two can form heterodimers. These enzyme systems, from their tissue specificities and post‐fertilization stages of appearance, should be useful for studies of gene activation in X. laevis development.
Acclimation to successive short term salinity changes by the bivalve Modiolus demissus. II. Nitrogen metabolism
Authors: Strange Kevin B. , Crowe John H. 
Published: June 2005

AbstractThe bivalve Modiolus demissus acclimates rapidly to new salinity regimes when exposed to successive short term osmotic stress. During exposure to hypoosmotic stress ventricular primary amine concentration decreases to an apparent steady‐state level within six hours, while hemolymph primary amine concentration increases. Upon re‐exposure to 100% sea water following a 6‐hour hypoosmotic stress, intracellular primary amines increase rapidly and return to control levels after six hours of exposure. Concomitant with this is an apparent decrease in hemolymph primary amine concentration. The rapidity with which reacclimation to hyperosmotic media proceeds and the pattern of change of individual amino acids suggests that transport of hemolymph FAA may play an important role in cell volume regulation induced by increases in external salinity.
Stimulation of mitosis in cultured limb blastemata of the newt, Notophthalmus viridescens
Authors: Carlone Robert L. , Foret J. E. 
Published: June 2005

AbstractExperiments were performed in vitro to assess the mitogenic activity of brain homogenates and cyclic nucleotides on adult newt limb blastemal cells. Early cone stage blastemata were explanted into organ culture, and thus denervated. The mitotic index (M.I.) of each was calculated and shown to decline steadily in vitro. The inclusion in the medium of newt brain homogenate (NBH) or dibutyryl cAMP (dbcAMP) delayed the loss of mitotic activity. Cyclic GMP alone or in combination with theophylline was ineffective as a mitogen. Bovine serum albumin and fetal calf serum were also ineffective, thus the mitogenic activity of brain homogenate appears to be distinct from a simple enrichment of the culture medium. Preliminary characterization of the active principles in NBH revealed a mitogenic activity that was both heat labile and trypsin sensitive. In related experiments, control cultures were maintained for 54 hours, roughly equivalent to one urodele blastemal cell cycle. When the decline in M. I. had stabilized, NBH or dbcAMP were added to the medium. A burst of mitotic activity was observed in both cases 8 hours later. Cyclic GMP was again ineffective. Since the G2 phase of the blastemal cell cycle lasts approximately four to eight hours, this result lends support to the hypothesis that blastemal cells are blocked in G2 in the absence of nerves. Cyclic AMP mimics the effect of brain homogenates at a specific phase of the blastemal cell cycle in vitro, and may therefore play some as yet undefined role in this neurotrophic process in vitro.
Western fence lizard (Sceloporus occidentalis) chemical signals. I. Conspecific discriminations and release of a species‐typical visual display
Authors: Duvall David 
Published: June 2005

AbstractWestern fence lizards, Sceloporus occidentalis, were exposed to markings, droppings, and exudates (e.g., femoral and proctodeal gland secretions, and feces) collected from conspecific males and females in a chemicalcue, simultaneous discrimination procedure. Females performed no discrimination between unmarked brick surfaces and those labelled by conspecifics of either sex, as indexed by relative numbers of substrate licks or tongue flicks. Males performed significantly more of these actions to male‐ but not female‐labelled surfaces. Immediately subsequent to licks of labelled surfaces, but never after licks of unlabelled surfaces, both sexes performed push‐ups, a visual display in this genus. These findings suggest that these lizards are capable of discriminating and utilizing chemical signals as a mode of social communication, and that chemical signals alone are capable of releasing a visual display from conspecifics.
Hormonal control of apolysis in barnacle mantle tissue epidermis, in vitro
Authors: Freeman John A. , Costlow John D. 
Published: June 2005

AbstractEcdysterone (5–20 μg/ml) stimulated apolysis in inner mantle tissue explants of the barnacle, Balanus amphitrite, maintained under in vitro conditions. Apolysis was noticeable after 12 to 15 hours while complete apolysis was reached by 24 hours. Enlargement of the epidermal cells was also observed in ecdysterone‐stimulated tissues. Ecdysone (10–20 μg/ml) was equally as effective as ecdysterone in stimulating apolysis. In some tissues, which had been cultured with 20 μg/ml ecdysterone for 24 hours, new cuticle formation had occurred following apolysis. The initiation of apolysis by ecdysterone was dependent on RNA and protein synthesis, as indicated by the inhibition of ecdysterone‐promoted apolysis by actinomycin D and cycloheximide. Aqueous extracts of shrimp eyestalks (MIH) (10 es eq/ml), either as a crude extract, or as a low molecular weight fraction from a Sephadex G‐25 column, were active in repressing the apolysis‐stimulating action of ecdysterone. The MIH activity could be overridden by increased levels of ecdysterone. Protease treatment of the MIH from crude and partially purified fractions abolished the inhibitory activity. Molt‐inhibiting hormone did not bind 3H‐ecdysterone. The results demonstrate that the early premolt integumental activities are under the control of ecdysterone and molt‐inhibiting hormone.
Neural regulation of cholinesterase in newt skeletal muscle. I. Distribution and characterization of the enzyme species
Authors: Rathbone Michel P. , Vickers John D. , Ganagarajah Mailvaganam , Brown Judy A. , Logan David M. 
Published: June 2005

AbstractThe molecular forms of acetylcholinesterase (AChE) in triceps muscles of newts (Notophthalmus viridescensiwere identified and their distribution in the muscle determined. Six forms of AChE were separated from crude muscle homogenates using velocity sedimentation on sucrose gradients. Their sedimentation coefficients were 16.5S, 1226, 9.8S, 7S, 5.5S, and 3.7S. They were identified as acetylcholinesterases by their ability to hydrolyze acetyl‐β‐methylcholine, but not butyrylthiocholine. The 7S form, however, has not been as thoroughly characterized as it can only be consistently identified in sucrose gradients of Tris‐Triton X‐100‐NaC1 extracts of muscle previously extracted with Tris‐Triton X‐100. The Tris‐Triton X‐100 extraction removes the 5.55 and 9.8S AChE forms which mask the 7S form in sucrose gradients of unfractionated material. The region of muscle containing the motor endplates was enriched in the 16.5S form, whereas the musculotendinous junction contained a high proportion of the 12.8S form. Contamination by AChE present in blood and nerve, did not account for the distribution of the 12.8S species within the muscle. The 3.7S and 5.5S forms were soluble in Tris buffer and are probably located in the cytoplasm. The 9.8S forms required 1MNaCl for solubilization, indicating that it is associated with an osmotic shock‐resistant intracellular compartment, possibly the sarcotubular system. Triton X‐100 was required to solubilize the 16.5S, 12.8S and 7S forms indicating that they may be membrane bound. Crude muscle homogenates and each of the forms of AChE isolated on sucrose gradients yielded nine bands of AChE activity when subjected to polyacrylamide gel electrophoresis (PAGE). The bands of AChE were apparently monomers and multimers from which the larger forms of AChE were assembled.
Isolation of O‐phosphorylethanolamine from the erythrocytes of an elasmobranch (the Southern Fiddler Ray — Trygonorhina fasciata guanerius)
Authors: Coates Michael , Thompson Judith , Tate M. E. 
Published: June 2005

AbstractAn amphoteric organic phosphate, which represents 20% of erythrocyte acid soluble phosphate components from an elasmobranch (the Southern Fiddler Ray — Trygonorhina fasciata guanerius) has been isolated as a colourless crystalline solid. Its phosphorus content, melting point behaviour, chromatographic, electrophoretic and ion‐exchange properties, together with its infrared and electron impact mass spectra are consistent with its formulation as O‐phosphorylethanolamine.Assuming minimal degradation in the isolation procedure, the calculated erythrocyte intracellular concentrations of characterised phosphates from the Southern Fiddler Ray are as follows: O‐phosphorylethanolamine (1.89 mM), adenosine triphosphate (1.61 mM), inorganic phosphate (0.26 mM), inosine monophosphate (0.47 mM), guanosine triphosphate (0.34 mM) and adenosine diphosphate (0.11 mM). On a molar basis O‐phosphorylethanolamine is the major acid soluble phosphate of the Southern Fiddler Ray erythrocyte, but examination of the literature suggests its concentration may vary considerably among other elasmobranchs and possible reasons for such variance are considered.
Tissue culture evidence on the control of the switch from contact inhibition of cell movement to overlapping behavior in annual fish embryos of nothobranchius korthausae
Authors: Lesseps Roland J. , Lapeyre Michel V. , Hall Marian V. 
Published: June 2005

AbstractDeep blastomeres of annual fish embryos exhibit contact inhibition of cell movement during epiboly and early dispersed stages before returning to self‐cohering and overlapping behavior. Deep blastomeres were dissociated from embryos of several different ages and cultured in hanging drops and in sitting drops. In every culture the cells rapidly reaggregated, irrespective of whether the cells were aggregated or dispersed in the living embryo. In sitting‐drop cultures, some cells subsequently flattened onto the plastic surface and assumed a fibroblastic shape. These results indicate that the contact inhibition and the overlapping behavior exhibited by deep blastomeres in vivo depend upon interactions of these cells with their embryonic environment, probably with the cell layers on which they are moving.
A proctolin‐like peptide in crab pericardial organs
Authors: Sullivan Robert Emmett 
Published: June 2005

AbstractEvidence is presented that one of the cardio‐excitatory peptides known from crab pericardial organs is identical to or a close analog of proctolin, a putative peptide‐transmitter in insects. Acid ethanol extracts of crab pericardial organs contain a cardioexcitatory peptide which is pharmacologically and chromatographically indistinguishable from proctolin. The peptide exhibits an apparent molecular weight of approximately 600 as determined by gel filtration, is not degraded by trypsin but readily inactivated by leucine aminopeptidase. Application of this decapod cardioexcitatory peptide to the cockroach gut effects a dose‐dependent contracture identical to that produced by proctolin. Similarly, proctolin elicits a characteristic inotropic response from crab hearts.
Paternal X chromosome expression in extraembryonic membranes of XO mice
Authors: Frels William I. , Chapman Verne M. 
Published: June 2005

AbstractThe paternally derived allelic form of the X chromosome linked enzyme phosphoglycerate kinase (PGK‐1) is expressed in both the fetus and extraembryonic membranes of 9.5 day post coitum XO (XPO) mouse conceptuses. Previous studies on trophectoderm and primitive endoderm derived extraembryonic membranes in XX conceptuses suggest expression of only the maternally derived X chromosome (Xm). Our results suggest that the observed lack of expression of XP in the trophectoderm and primitive endoderm derivatives of XX embryos is not an intrinsic property of the XP chromosome.
Salt and water balance in the oligohaline clam, Rangia cuneata I. Anisosmotic extracellular regulation
Authors: Henry Raymond P. , Mangum Charlotte P. 
Published: June 2005

AbstractThe euryhaline mollusc Rangia cuneata maintains blood NaCl above that in the ambient medium in the range 0–2 ppt salinity and below ambient in the range 12–24 ppt. A hyperosmotic condition of the blood found at low salinity disappears at 12–16 ppt, and the blood medium‐difference becomes labile at high salinity. Hypersaline regulation of the blood at low salinity is accompanied by increased oxygen uptake, both in intact animals and in isolated gill and mantle tissue. However, only mantle andnot gill oxygen uptake is depressed at low salinity by ouabain, a specific inhibitor of the Na+ + K+ ATPases. These findings, together with other results on enzyme activity and the ionic effects on enzyme inhibition, suggest that hyperosmotic regulation of the blood at low salinity involves the absorption of NaCl from the medium, and that the process requires both oxidative metabolism and unimpaired functioning of the Na+ + K+ ATPases. The excretion of ammonia is also, depressed by ouabain, suggesting an exchange of Na+ and NH4+. The NH4+ may arise during deamination of intracellular free amino acids. The size of the free amino acid pool in gill, mantle and adductor muscle, varies directly with ambient salinity. Although the evidence is less complete, we also suggest that the hyposaline condition of the blood at high salinity results from an active process, and depends upon the uninhibited activity of the Na+ + K+ ATPases.
The effect of anemia on metabolic performance in the frog, Rana pipiens
Authors: Hillman Stanley S. 
Published: June 2005

AbstractAnemias were induced in Rana pipiens hemolytically and by repetitive bleedings. Maximal rates of oxygen consumption ( max) declined with anemia. The pattern of decline in max with anemia did not closely approximate theoretical predictions of systematic oxygen transport. Anemic frogs accumulated lactate faster than control frogs during exercise. The length of exercise time to fatigue (stamina) was positively correlated with both gastrocnemius and blood lactate concentrations, indicating that fatigue was not dependent on a threshold lactate concentration in muscle or blood. Anemic frogs had the same stamina as control frogs.
Evidence suggesting a role for cyclic nucleotides in acrosome reactions of hamster sperm in vitro
Authors: Mrsny Randall J. , Meizel Stanley 
Published: June 2005

AbstractThere have been conflicting reports concerning the involvement of cyclic nucleotides in sperm capacitation. We have examined the effects of micromolar concentrations of dibutyryl cyclic AMP (Bt2cAMP) and of the phosphodiesterase inhibitors SQ20009 and ICI63,197 on hamster sperm incubated under in vitro capacitating conditions. Washed hamster sperm were incubated in a capacitation media containing bovine serum albumin, and a protein‐free “motilityfactor” from bovine adrenal cortex. Incubation for 3.5 hours was followed by addition of one of the compounds (0.1–10 μM) or control buffer. At the time of addition and after 30–120 minutes further incubation, sperm were examined by phase contrast microscopy. The final motility was similar to the, initial motility (50–70%) and the same in incubation of controls or experimental compounds. Bt2cAMP, SQ20009, and ICI63,197 at these concentrations stimulated acrosome reactions to a statistically significant extent (P <0.005) compared to controls. Activation was stimulated to a varying degree by all three experimental compounds. These results suggest a role for cyclic nucleotides in capacitation and the acrosome reaction of hamster sperm.
Salinity adaption of gill Na, K‐ATPase in the blue crab, Callinectes sapidus
Authors: Neufeld Gaylen J. , Holliday Charles W. , Pritchard John B. 
Published: June 2005

AbstractBoth male and female blue crabs were shown to hyperosmoregulate efficiently at low salinities. The posterior gill pairs, particularly numbers six and seven, exhibited the highest specific activity of Na, K‐ATPase in crabs adapted to full‐strength seawater. When the crabs were acclimated to 200 mOs/kg, Na,K‐ATPase activity increased in all gill pairs, with the most pronounced increase in gills six and seven (∼ 80%). Crabs which had been acclimated to waters of 1000, 800, 500, and 200 mOs/kg showed asequential increase in Na, K‐ATPase activity which matched the decrease in medium osmolality. At the lowest salinity, the increase was somewhat greater in males, approximately 26% higher than in females. In crabs adapted to 100% seawater, the highest enzyme activity was localized in the lateral one‐third of the gill lamellae, near the afferent vessel. Acclimation to low salinities was accompanied by a significant increase in Na,K‐ATPase activity in the middle and medial portions of the gill. Abrupt transfer of crabs from 1000 mOs/kg to 200 mOs/kg, or vice versa, resulted in rapid changes in hemolymph osmolality which stabilized within 24 hours. However, the Na,K‐ATPase activity changed gradually and did not reach equilibrium levels until 12 to 18 days,after transfer. These data suggest that Na,K‐ATPase activity was altered primarily by synthesis and degradation, rather than by modulation of the activity of existing enzyme.
Amino acid metabolism and cell volume regulation in the little skate, Raja erinacea. I. Oxidation
Authors: King Patricia A. , Cha Chung‐Ja , Goldstein Leon 
Published: June 2005

AbstractThe capacity of isolated tissues of the little skate (Raja erinacea) to oxidize β‐alanine, sarcosine, and taurine, and the role of amino acid oxidation in the modulation of intracellular free amino acid concentrations was investigated in vitro. Liver was found to be the primary site of β‐alanine and sarcosine oxidation. Chronic acclimation of skates to half‐strength sea water increased in vitro oxidation of β‐alanine and alanine by liver slices. Taurine oxidation could not be detected in any of the tissues tested. In vivo studies showed that taurine is excreted intact and that excretion increases significantly following acute acclimation of skates to half‐strength sea water.
Age and endocrine effects on fat body metabolite composition in adult male Blaberus discoidalis cockroaches
Authors: Mannix John J. , Keeley Larry L. 
Published: June 2005

AbstractEndocrine‐and age‐related changes in metabolite contents were used as a measure of fat body development and function in adult male Blaberus discoidalis cockroaches. Fat body dry weight, protein, glycogen, and lipid levels coordinately decreased at days two to three of adult life, increased at day four, then declined to lower stable levels by days six to seven. The metabolite contents remained stable from days seven through ten and were still at this level on day 30. Long‐term endocrine deficiencies resulting from corpora cardiaca‐allata extirpation did not change the amounts of metabolites present at 30 days of age. The fat body DNA content remained constant regardless of age or endocrine balance. Unlike other metabolites, the RNA content increased to twice its original level during the first six days of adult life and was unaffected by either age or endocrine balance thereafter. The findings suggest that the adult fat body changes from a storage function at the time of the nymphal‐adult molt to a biosynthetic function by day six. The transition is independent of endocrine control by the corpora cardiaca‐allata complex.