bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on histocompatibility in natural populations of freshwater sponges
Authors: Mukai Hideo , Shimoda Hitoshi 
Published: June 2005

AbstractHistocompatibility in natural populations of individuals was examined for the following four Japanese species of freshwater sponges: Ephydatia fluviatilis, Ephydatia muelleri, Radiospongilla cerebellata, and Eunapius fragilis. Gemmules were obtained from field‐grown specimens. Then, using juvenile sponges hatched from gemmules, fusibility was tested in the laboratory. Every interspecific combination among these four species displayed non‐fusion with no cytotoxic interaction. For all species, the occurrence of allogeneic histoincompatibility was assured, but manifestation of incompatibility was different from species to species. Among 36 specimens of E. fluviatilis collected from three localities, two strains nonfusible with each other were distinguished. Each locality was populated by a single strain. Specimens of E. muelleri were obtained from two localities. All combinations of specimens coming from the same locality were compatibly fusible, but those between specimens coming from different localities displayed conspicuous cytotoxic rejection reaction. This reaction occurred asymmetrically, resulting in the destruction of one partner. In R. cerebellata, two types of reactions, fusion and rejection, were also distinguished. In rejection, cytotoxic reaction occurred bilaterally and symmetrically in and around the contact zone. A total of 40 specimens, collected from a single pond, could be divided into 16 groups by their fusibility. As to E. fragilis, some combinations of specimens were compatibly fusible; the others displayed various degrees of incompatibility. In completely incompatible combinations, the paired sponges simply showed nonfusion with no sign of cytotoxic reaction. In more weakly incompatible combinations, the paired sponges were separated after initial fusion, the degree of which was variable depending on combination. A total of 59 specimens, collected from a single pond, could be classed into 14 groups by their fusibility. In both R. cerebellata and E. fragilis, some intergroup combinations were compatible, giving rise to probable genetic chimeras. Such chimeric sponges persisted with no sign of segregation for more than 1 month in the field.
Ca+ + localization in boar spermatozoa by the pyroantimonate technique and X‐ray microanalysis
Authors: Berruti Giovanna , Franchi Emilia , Camatini Marina 
Published: June 2005

AbstractIntracellular, loosely bound Ca+ + has been localized electron microscopically in freshly ejaculated boar spermatozoa by in situ precipitation with potassium antimonate. Ca+ + was identified as the cation precipitated by testing the EGTA‐sensitivity of the precipitates and by X‐ray microprobe analysis. The data obtained revealed that the outer acrosomal membrane is the preferential site for Ca+ + precipitation in the sperm head.
Morphogenetic waves in the development of the lateral mesoderm in the Mexican axolotl (Ambystoma mexicanum) and their relationship to pronephric duct migration
Authors: Gillespie Laura L. , Armstrong John B. 
Published: June 2005

AbstractThat portion of the lateral mesoderm capable of supporting migration of the pronephric duct was mapped by transplanting secondary ducts ventral to the primary duct. Ducts transplanted more anterior than the primary duct did not migrate, whereas those transplanted more than 2 somitewidths posterior to the primary duct appeared to be delayed in the onset of migration. These transplants thus define an “active” region that extends approximately from the posterior margin of the last‐formed somite to the position of the primary duct tip, about 2 somite‐widths anterior. The anterior boundary of the active region coincides with a wave of shape change that passes in a craniocaudal direction through the lateral mesoderm. In this wave, the mesoderm changes from a two‐cell to a single‐cell layer and then back to a two‐cell layer. The duct tip is always located over the single‐cell layer. We also examined the distribution of extracellular matrix (ECM) between the mesoderm and epidermis. The posterior limit of the ECM was always posterior to the duct tip but did not extend beyond the last‐formed somite.
Biochemical changes in the composition of the testes during spermatogenesis in the sea starAsterias vulgaris
Authors: Smith Frank F. , Walker Charles W. 
Published: June 2005

AbstractExamination of major biochemical classes during the spermatogenic cycle provides a definition of the changing chemical microenvironment influencing germinal cells and also suggests temporal relationships among successive spermatogenic events. Testes from sea stars collected throughout the year were homogenized and lyophilized, and aliquots were assayed for DNA, RNA, total protein, free amino acids, total lipids, glycogen, and other carbohydrates; spermatogenic stage was determined by examination of paraffin sections. The resulting data, expressed as 1) mg/g dry mass, 2) mg/mg DNA, and 3) total content, were analyzed by weighted periodic regression and circular‐linear correlation with spermatogenic stage and time of year.With the exception of lipid/DNA, all components show a significant regression against time. DNA concentration increases during the proliferative and differentiative phases, attaining maximal values late in the differentiative phase; DNA synthesis appears to be essentially complete by the end of March. RNA concentration increases in the late aspermatogenic phase, as testicular cells begin preparations for proliferation, and remains high until late in the differentiative phase. Protein accumulates during proliferation, preceding the accumulation of DNA, but then gradually declines during differentiation. Free amino acids, simple sugars, and glycogen all increase during the aspermatogenic phase, possibly as a result of nutritive input.The observed patterns of change correlate closely with cytological variations observed within the germinal epithelium. Biochemical data thus complement existing data on the cytology of the germinal epithelium.
Plasma levels and renal handling of endogenous amino acids in snakes: A comparative study
Authors: Benyajati Siribhinya , Dantzler William H. 
Published: June 2005

AbstractPlasma levels of 22 endogenous amino acids were measured by ion‐exchange chromatography in four species of snakes: Thamnophis sirtalis, T. radix, Aipysurus laevis, and Python molurus. Despite considerable interspecific variation in the amino acid composition, all species showed relatively high plasma concentrations of histidine, a feature apparently unique to reptiles. The renal handling of these amino acids was studied by renal clearance methods. As in other vertebrates, net tubular absorption of filtered amino acids predominated. However, net tubular secretion of taurine, cysteic acid and/or phosphoserine and β‐alanine was observed, with taurine being the predominant amino acid secreted. The percentage reabsorption of the total amino acids filtered by the snake kidneys ranged from 79 to 95%. Evidence for the postrenal absorption of amino acids in these reptiles is presented. In species that normally undergo hibernation (Thamnophis spp.), the ability of the kidney to reabsorb amino acids was depressed by cold acclimation. Cold acclimation significantly decreased plasma levels of all amino acids except taurine, whose concentration increased. The increase in plasma taurine level may have resulted from cellular osmoregulation. Under these conditions, renal excretion of taurine increased concomitantly with the increase in plasma taurine concentration.
31P‐NMR studies of Limulus polyphemus: Spermatozoa at rest and after motility
Authors: Robitaille Patricia A. , Robitaille Pierre‐Marie L. , Brown George G. 
Published: June 2005

AbstractPhosphorus‐31 nuclear magnetic resonance spectroscopy (31PNMR) was used to monitor changes in the levels of several high‐energy compounds both prior to and following the initiation of motility in spermatozoa of the horseshoe crab, Limulus polyphemus L. These spermatozoa are easily collected and are nonmotile until stimulated with a sperm‐motility‐initiating peptide (SMI) which can be extracted from Limulus eggs. Following the addition of SMI, several changes in metabolite levels within the spermatozoa were obtained, the most significant of which were a decrease in nucleotide triphosphate (NTP) and phosphoarginine levels and an increase in the levels of inorganic phosphate (Pi), NDP, and phosphomonoesters. An increase in the intracellular pH (0.45 pH units) of the sperm was also noted following the completion of SMI‐stimulated motility.
Pronounced influence of Hb‐O2 saturation on red cell pH in tench blood in vivo and in vitro
Authors: Jensen Frank B. 
Published: June 2005

AbstractAt an extracellular pH of 7.9 the red cell pH in tench blood exhibits a nonlinear, strongly inverse relationship with Hb‐O2 saturation, both when investigated in vitro and in vivo (in fish exposed to acid water with and without aluminium). The pHi difference between deoxygenated and oxygenated erythrocytes is large (i.e., 0.35 pH units), which can be accounted for by the Haldane effect and the buffering properties of the blood. The major shift in pHi occurs between 50 and 100% Hb‐O2 saturation, indicating an almost full exploitation of the Haldane effect within the normal physological range of blood O2 saturations.
Cyclic AMP stimulation of Cl− secretion by the opercular epithelium: The apical membrane chloride conductance
Authors: Degnan Kevin J. 
Published: June 2005

AbstractChloride secretion (Isc) by the opercular epithelium of the teleost, Fundulus heteroclitus, is stimulated by elevations in intracellular cyclic AMP (cAMP) elicited by β‐adrenergic agonists, such as isoproterenol, and is accompanied by a small but significant increase in the transepithelial conductance (Gt). Cupric ions (Cu2+) have been shown to block the apical membrane CI− channels in this epithelium, leading to a reduction in both the Isc and Gt (Degnan, '85). In the present studies, the effects of Cu2+ on cAMP‐elevated and cAMP‐depleted epithelia were observed to define the actions of cAMP in this stimulatory process. At a concentration of 5 × 10−4 M in the mucosal solution, Cu2+ inhibited the Isc 79.8% and reduced the Gt 39.2%. Isoproterenol produced an attenuated stimulation of the Isc in these tissues compared to untreated controls, but had no effect on the Gt. In tissues bathed bilaterally with Cl− ‐free Ringer, the Isc was virtually abolished and the Gt was reduced 37.0%; neither Cu2+ nor isoproterenol had any effects on the Isc or Gt under this condition. Simultaneous 22Na and 36 Cl unidirectional flux determinations indicated that the only effects of both isoproterenol and Cu2+ were on the active Cl‐ secretory flux. An inhibitor of adenylate cyclase, 2′,5′ dideoxyadenosine (DDA), reduced the Isc and Gt 39.8% and 20.8% respectively. This inhibitor had no additional effects in Cu2+ ‐treated tissues and the action of Cu2+ on the Gt was reduced in DDA‐treated tissues. The results indicate that cAMP stimulation of Cl− secretion involves only the active transcellular Cl− pathway and is accomplished in part by an increase in a Cl− ‐dependent, mucosal Cu2+ ‐inhibitable increase in the Gt, which is most likely localized to the apical membrane of the chloride cell.
Attenuated cardiovascular effects of prostaglandin I2 and prostaglandin F2α in cold acclimated American bullfrogs, Rana catesbeiana
Authors: Herman Ceil A. , Robleto Daniel O. , Mata Paula L. , Lujan Monica D. 
Published: June 2005

AbstractAmerican bullfrogs, Rana catesbeiana respond to prostaglandins with changes in heart rate and blood pressure. These studies compare responses of warm (22°C) and cold acclimated (5°C) bullfrogs to prostaglandins. Gas chromatographic analysis determined equivalent fatty acid profiles in total lipids of heart and artery tissue from warm and cold acclimated animals. Arachidonic acid was the fatty acid precursor found in greatest abundance in both groups. For cardiovascular experiments, bullfrogs were cannulated by using a T‐cannula implanted in the right sciatic artery. In warm acclimated bullfrogs, preinfusion systemic arterial pressure (SAP) was 14.7 ± 0.5 mm Hg, and heart rate was 33.0 ± 1.7 beats/min. Cold acclimated bullfrogs had SAP values of 8.0 ± 0.8 mm Hg, and heart rate was 6.9 ± 0.3 beats/min. Arachidonic and eicosapentaenoic 3‐acid infusions (2,000 μg/kg body weight [bw]) were hypertensive in cold acclimated and hypotensive in warm acclimated animals. These effects were blocked by indomethacin (4 mg/kg bw). In both warm and cold acclimated bullfrogs, prostaglandin F2α (3–100 μg/kg bw) was hypertensive, while prostaglandin I2 (0.03‐3 μg/kg bw) was hypotensive, with both prostaglandins stimulating a greater absolute response in warm acclimated animals. In addition, both prostaglandins increased heart rate in warm but not in cold acclimated bullfrogs. The results suggest diminished cardiovascular sensitivity to prostaglandins at low environmental temperatures.
Cell surface carbohydrate involvement in controlling the adhesion and morphology of neural crest cells and melanophores of Xenopus laevis
Authors: Milos Nadine C. , Wilson H. Chris 
Published: June 2005

AbstractPieces of dorsal neural tube (stages 22–23) or late neural crest tissue (stages 24–26) of Xenopus laevis were cultured. Migratory cells moved out of explants to form an outgrowth of multipolar melanophores on the substratum. Treatment with β‐galactosidase (0.1–0.4 U/ml) to remove cell surface galactose was correlated with detahment of melanophores. In the presence of lower concentrations of this enzyme the shapes of these cells were converted to arborized, spidery morphologies and cell movement was inhibited. Unpigmented cells were affected more slowly. Neuraminidase treatment, to remove cell surface sialic acid and expose more galactose, only affected melanophores. These became increasingly spread on the substratum and cell overlap was observed. These results suggest that the relative amounts of galactose and sialic acid at the cell surface become increasingly important in controlling cell adhesion as X. laevis neural crest cells migrate and differentiate into melanophores.
Osmolarity affects oxidation of sarcosine by isolated hepatocytes and mitochondria from a euryhaline elasmobranch
Authors: Ballantyne J. S. , Moyes C. , Moon T. W. 
Published: June 2005

AbstractHepatocytes isolated from the little skate, Raja erinacea, oxidize sarcosine at higher rates in hypoosmotic media and at lower rates in hyperosmotic media. A similar pattern is noted for the oxidation of sarcosine by mitochondria isolated from the liver. These observations are consistent with a role for mitochondria in ridding the cell of osmotically active organic solutes during volume regulation in hypoosmotically stressed cells while allowing their accumulation during hyperosmotic volume regulation. Such a mechanism would be quantitatively more imporant in osmoconforming species but may occur in osmoregulating species as well.
The role of spindle microtubules in the timing of the cell cycle in echinoderm eggs
Authors: Sluder Greenfield , Miller Frederick J. , Spanjian Kristin 
Published: June 2005

AbstractSpindle microtubules play an important role in the mechanisms that control the timing of cell cycle events in the eggs of the sea urchins L. variegatus and L. pictus. However, recent work which used colchicine to block microtubule assembly in the eggs of two other echinoderms, S. purpuratus and D. excentricus, has raised serious questions about the generality of this role for spindle microtubules. Thus, we have systematically examined the role of spindle microtubules in the timing of the cell cycle in the fertilized eggs of these latter species. We treated eggs of both species with 5–10 μM Colcemid for several minutes starting 30 min after fertilization to completely prevent spindle microtubule assembly for several h. We used Colcemid, instead of colchicine, because it is effective at lower doses and, at these doses, shows no detectable toxic side effects. We compared for control and treated eggs the time course of nuclear envelope breakdown/reformation and DNA synthesis. We found for both species that the eggs continue to cycle without spindle microtubules; mitosis is up to twice the normal duration while interphase remains essentially unaffected. To test for the possible toxic side effects of the 1–2 mM colchicine used earlier on S. purpuratus and D. excentricus, we treated eggs of these two species, and also those of L. variegatus, with 1 mM lumi‐colchicine. This photo‐inactivated form of colchicine, which does not bind to tubulin, substantially prolongs mitosis and, to a lesser extent, interphase. Thus, the results of the earlier work are most easily explained by the combination of specific and nonspecific effects of the 1–2 mM colchicine used. Our present results indicate that the importance of spindle microtubules in the mechanisms that control the timing of the mitosis portion of the cell cycle is a general phenomenon.
Requisites for growth and myelination of urodele sensory neurons in tissue culture
Authors: Olsen Cherie L. , Bunge Richard P. 
Published: June 2005

AbstractWe describe a system for long‐term culture of adult salamander dorsal root ganglia and present initial observations on the regulation of nonneuronal cell proliferation in this system. Observations of the region of axonal outgrowth in these cultures indicated that, on the one hand, fibroblasts proliferate equally well with neurons present or absent. Schwann cells, on the other hand, require not only the presence of neurons but also proximity to or contact with their neurites. These results indicate that neural tissue is not mitogenic for all cell types represented in the limb regeneration blastema. Further, we describe, for the first time, myelination of salamander axons in vitro. The critical factors found to be required for this high degree of differentiation were the use of long culture periods and addition to the culture medium of ascorbic acid, which is shown to promote extracellular matrix deposition. These observations correlate with extensive observations made on mammalian tissues in vitro, indicating a linkage between deposition of extracellular matrix and full expression of other Schwann cell functions. We anticipate this culture system will be useful in studies of limb blastema cell proliferation.
Photothermal effects on the testicular cycle in the musk turtle, Sternotherus odoratus
Authors: Mendonça Mary T. , Licht Paul 
Published: June 2005

AbstractA series of photothermal treatments was initiated at different times of year to examine the relative contributions of exogenous and endogenous factors affecting the timing of the testicular cycle of the kinosternid turtle, Sternotherus odoratus. Elevated temperature appeared to be the major factor stimulating testicular recrudescence (spermatocytogenesis, spermiogenesis, and, to some extent, androgen secretion). However, depending on the time of year, short or long daylengths, in conjunction with elevated temperatures, enhanced testicular responses (recrudesence or regression). Also, high temperatures are not requisite for recrudescence. Spermatogenic activity and testis growth differ in their temperature sensitivity and may become disscociated, and an endogenous mechanism may have affected peak androgen secretion. Testicular regression exhibited a dependence on an interaction among temperature, photoperiod, and endogenous regulation. Turtles with testes in advanced stages of spermiogenesis underwent accelerated regression when exposed to even slightly reduced temperatures, especially at short daylengths. However, regression was delayed by a combination of high temperature and short daylength in fall. Results are compared to other experimental studies of photothermal effects on turtles and discussed in terms of the described latitudinal variations in the timing of the testicular cycle of S. odoratus.
Fructose‐6‐phosphate is not a substrate for glucose‐6‐phosphate dehydrogenase
Authors: Jeffery Jonathan , Wood Irene 
Published: June 2005

AbstractD‐Fructose‐6‐phosphate was shown not to be a substrate for glucose‐6‐phosphate dehydrogenases (EC. 1.1.1.49) from human erythrocytes, bovine adrenal, rat liver, three yeasts (brewer's yeast, baker's yeast, and Candida utilis), and Leuconostoc mesenteroides. These findings contrast with those of G.M. Kidder (J. Exp. Zool., 226:385–390, '83).
A new enzyme from Drosophila melanogaster: In vitro conversion of xanthommatin into its dihydroform by means of xanthommatin reductase
Authors: Santoro P. , Parisi G. 
Published: June 2005

AbstractA new enzyme was partially purified from D. melanogaster. The enzyme catalyzes the reduction of xanthommatin to dihydroxanthommatin in the presence of NADH/H+ as confactor. FAD, FMN, p‐chloromercuribenzoate, 2‐amino‐4‐hydroxypteridine and biopterin inhibited the enzyme activity. The inhibitory effect of some pterines suggests a correlation between the synthesis of dihydroxanthommatin and that of pterines. It has been suggested that the enzyme may participate, in vivo, in the reduction of xanthommatin.
Oogenesis in Fundulus heteroclitus IV. Yolk‐vesicle formation
Authors: Selman Kelly , Wallace Robin A. , Barr Valarie 
Published: June 2005

AbstractYolk vesicles first appear within the oocyte of Fundulus heteroclitus in association with elaborate smooth endoplasmic reticulum and Golgi elements. Cytochemistry indicates the yolk vesicles contain an acidic glycoconjugate. [3H]Glucose is used to examine the synthesis and accumulation of yolk vesicles in studies performed both in vivo and in vitro, since it is selectively incorporated into nascent yolk vesicles. The endogenous synthesis of yolk‐vesicle glycoconjugate is documented by autoradiography, gel electrophoresis, and fluorography. A large (> 200 kDa) glycoconjugate has been identified, which is thought to reside in yolk vesicles. Incorporation studies done in vitro substantiate that this putative yolk‐vesicle material is synthesized by the oocyte itself and that synthesis occurs not only during the so‐called yolk‐vesicle stage, but also throughout vitellogenesis and early maturation. The view is thus adopted that various synthetic and physiological events are sequentially initiated and subsequently remain active throughout oocyte growth.
Basolateral localization of Na+ + K+‐ATPase in gill epithelium of two osmoregulating crabs, Callinectes sapidus and Carcinus maenas
Authors: Towle David W. , Kays W. Todd 
Published: June 2005

AbstractAlthough Na+ + K+‐dependent ATPase, the enzymatic equivalent of the sodium pump, is thought to be restricted to the basolateral membrane of nearly all ion‐transporting epithelial cells, its absence from basolateral membranes of crustacean epithelia and/or its presence in apical membranes have been suggested by evidence from other laboratories. However, ultracytochemical localization of K+‐dependent, ouabain‐sensitive p‐nitrophenylphosphatase (p‐NPPase), using the method of Mayahara et al. ('80), indicated that Na+ + K+‐ATPase resides predominantly in the basolateral membrane of thick epithelial cells from gill lamellae of two euryhaline crabs, Callinectes sapidus and Carcinus maenas. Crab gill is therefore not unique in its Na+ + K+‐ATPase distribution and may be used as a model for experiments designed to investigate mechanisms of transepithelial Na+ uptake.