bluuebunny/crossref_metadata_2025_split huggingface dataset:
Presence of a trypsin‐like protease in starfish sperm acrosome
Authors: Sousa Mário , Moradas‐Ferreira Pedro , Azevedo Carlos 
Published: June 2005

AbstractMarthasterias glacialis sperm cells were treated with ionophore A23187, centrifuged, and the supernatants were assayed for esterase activity. With N‐benzoyl‐L‐arginine ethyl ester‐HCl (BAEE) as substrate, a net activity was determined which was not detectable when N‐acetyl‐L‐tyrosine ethyl ester (ATEE) was used. The BAEE trypsin‐like activity was inhibited by soybean trypsin inhibitor (SBTI), N‐α‐p‐tosyl‐L‐lysine chloromethyl ketone‐HCl (TLCK), and phenyl methyl sulfonyl fluoride (PMSF), but not by L‐1‐tosylamido‐2‐phenylethyl chloromethyl ketone (TPCK). The presence of proteolytic activity in acrosomal exudates was further demonstrated by gelatin‐sodium dodecyl sulfate‐polyacrylamide gel electrophoretic zymography (gelatin‐SDS‐PAGE). The presence of several bands of low proteolytic activity and of one band of high proteolytic activity, which also has the lower molecular weight, together with the fact that all are inhibited by benzamidine, suggests the existence of a trypsin‐like proteinase system. The effect of the acrosomal exudate on the oocyte jelly coat was investigated by SDS‐PAGE analysis. All jelly proteins appeared to be digested by the acrosomal enzymes. Furthermore, if SBTI is added shortly after insemination, the sperm fail to fertilize the oocytes. These results indicate that the starfish sperm acrosomal vesicle contains a trypsin‐like protease which may be involved in sperm penetration through the oocyte jelly coat.
Tissue‐specific metabolism during normothermy and daily torpor in deer mice (Peromyscus maniculatus)
Authors: Nestler James R. 
Published: June 2005

AbstractPrevious work with deer mice (Peromyscus maniculatus) has demonstrated that a significant acidosis occurs during daily torpor. In addition, carbohydrate levels are significantly lower, whereas fatty acid and ketone levels are significantly higher during torpor. The present study examined the effects of these in vivo acid‐base and metabolite adjustments on in vitro 14C‐glucose metabolism in tissues taken from normothermic and torpid deer mice. Glucose oxidation in liver and vastus lateralis taken from normothermic animals was reduced by a change in incubation temperature from 37°C to 25°C (liver, 0.44 to 0.23 μmoles/g.h; vastus, 0.66 to 0.25 μmoles/g.h), whereas heart from normothermic mice exhibited an increase from 0.57 to 0.99 μmoles/g.h at the lower temperature. Altering acid‐base conditions or metabolite levels had no effect on glucose metabolism in the heart or liver. However, both of these factors significantly influenced metabolism in vastus. Vastus taken from normothermic mice had an increased glucose oxidation rate under the more acidic torpor conditions (0.25 to 0.33 μmoles/g.h), whereas a reduction in oxidation occurred when incubated with torpor substrate concentrations (0.33 to 0.22 μmoles/g.h). In vastus taken from torpid mice, changing acid‐base state and metabolites to torpor levels resulted in a significant reduction in glucose oxidation (0.26 to 0.12 μmoles/g.h). Under most incubation conditions, glucose oxidation was significantly lower in tissues taken from torpid mice than in these tissues from normothermic mice, suggesting that adjustments in addition to changes in acid‐base and substrate parameters may be necessary to account for metabolic modifications during daily torpor. © 1992 Wiley‐Liss, Inc.
Thyroid hormone stimulates gastric development in flounder larvae during metamorphosis
Authors: Miwa Satoshi , Yamano Keisuke , Inui Yasuo 
Published: June 2005

AbstractTo elucidate the hormonal regulatory mechanisms of gastric development of the flounder, Paralichthys olivaceus, premetamorphic flounder larvae were treated with either 100 ppb of L‐thyroxine sodium salt (T4), or 30 ppm of thiourea (TU, a goitrogen) by dissolving drugs in ambient seawater. Control fish were reared in untreated seawater. Measurement of gastric gland volume with an image analyzing system revealed that the T4 treatment markedly increased the volume of the glands. Immunocytochemistry using an antiserum raised against purified quail pepsinogen as the primary antibody showed precocious appearance of pepsinogen‐like immunoreactivity in the gastric glands of the larvae treated with T4. In contrast, the gastric glands of the larvae treated with TU remained undifferentiated throughout the experiment. The volume of the glands of TU‐treated larvae was very small and immunoreactivity for antiquail pepsinogen was very weak even at the end of the experiment (4 weeks after the start of the experiment) when control fish had well‐developed gastric glands. These results strongly suggest that thyroid hormone stimulates differentiation of gastric glands during metamorphosis of the flounder. © 1992 Wiley‐Liss, Inc.
Relationship between cell size and nuclear volume in nucleated red blood cells of developmentally matched diploid and tetraploid mouse embryos
Authors: Henery C. C. , Kaufman M. H. 
Published: June 2005

AbstractAnalysis of control diploid and polyploid amphibia indicated that cell and nuclear volumes were closely related to their ploidy, so that an increase in ploidy was generally associated with an increase in cell size. This relationship is also believed to occur in mammalian polyploids. However, since the latter are only rarely encountered spontaneously, or only occasionally following experimental manipulation, no detailed morphometric studies have been carried out to date to confirm whether such a relationship exists. In this study, the cellular and nuclear volume of primitive red blood cells was analyzed in carefully developmentally matched control diploid mouse embryos and tetraploid embryos produced by the technique of electrofusion. All of the cells and/or nuclei studied had a characteristic spherical shape which greatly simplified the morphometric analysis. A defined and predictable relationship between ploidy and cellular and/or nuclear volume was observed in the red blood cells between 8.25 and 14.5 days of gestation. During this period the primitive red blood cells are gradually replaced by the definitive erythrocytes. The ratio of control values to tetraploid values was found to be close to the theoretical value of 1:2 when comparable cells and/or their nuclei were analyzed in carefully developmentally matched material. © 1992 Wiley‐Liss, Inc.
Serosa ontogeny in two embryonic morphs of Copidosoma floridanum: The influence of host hormones
Authors: Baehrecke E. H. , Grbić M. , Strand M. R. 
Published: June 2005

AbstractThe embryos of 2 larval morphs of the insect parasitoid Copidosoma floridanum (Ashmead) (Hymenoptera: Encyrtidae) were readily distinguished on the basis of temporal and morphological characters. Although larvae of the 2 morphs diftered in morphology and timing of hatch, both morphs derived a serosal membrane just prior to embryonic morphogenesis. Nuclei of the serosa increased in diameter and ploidy during development. Serosa polyploidy was similar in both morphs at identical stages of morphogenesis. Host endocrine perturbations that blocked C. floridanum morphogenesis also affected serosa development. Serosa ontogeny was blocked when the host was ligated at 7 h of the 4th stadium. Daily application of the juvenile hormone analogue methoprene starting at 20 h of the host's 3rd stadium resulted in serosal nuclei with greater diameters and ploidy values than those of untreated embryos. Treatment of the host with methoprene beginning at 20 h of the 3rd stadium followed by ligation at 7 h of the 4th stadium arrested serosa ontogeny and embryonic growth of the parasitoid. These data indicate that embryos of both morphs of C. floridanum formed a serosa just prior to morphogenesis and that serosa ontogeny required host head factors. Furthermore, host juvenile hormone did not influence serosa ontogeny but stimulated polyploidy of membrane nuclei. © 1992 Wiley‐Liss, Inc.
A highly repetitive interspersed sequence isolated from genomic DNA of the Medaka, Oryzias latipes, is conserved in three other related species within the genus Oryzias
Authors: Naruse Kiyoshi , Mitani Hiroshi , Shima Akihiro 
Published: June 2005

AbstractA highly repeated interspersed sequence (OLR1) was isolated from a genomic DNA library of the Medaka, Oryzias latipes. The OLR1 was about 160 base pairs (bp) in length. As judged from the results of colony hybridization experiments, OLR1 is one of the major repeated DNA sequences in the Medaka genome and is present in every 136 kb on average. Results of Southern and colony‐hybridization analyses indicate that OLR1 is a small interspersed repetitive element (SINE). OLR1‐related sequences were conserved in other three species (O. luzonensis, O. curvinotus, and O. mekongnensis) within the genus Oryzias as a repetitive sequence. These results lend support at the DNA level to the hypothesis that these four species form one group in the genus Oryzias, as has been suggested from an analysis of their karyotypes (Magtoon and Uwa, '85, Proc. Jpn. Acad., Ser. B, 61:157–160). © 1992 Wiley‐Liss, Inc.
Tissue‐specific and dietary control of alpha‐amylase gene expression in the adult midgut of Drosophila melanogaster
Authors: Thompson D. Bruce , Treat‐Clemons Lynda G. , Doane Winifred W. 
Published: June 2005

AbstractThe regulatory effects of allelic substitution at the trans‐acting mapP locus and of dietary glucose on the expression of the duplicate genes for alpha‐amylase (Amy) in Drosophila melanogaster were examined in the anterior midgut and posterior midgut regions of mature flies. The levels of amylase activity and amylase protein, as well as the abundance of amylase‐specific RNA, were quantified. All 3 parameters of Amy expression were concordant. Results indicate that the effects of both mapP and dietary glucose are exerted at the level of amylase RNA. However, the tissue‐specific effects of mapP are restricted to the posterior midgut and can therefore be distinguished from the effects of glucose in food medium, which influences amylase RNA levels in both the anterior and posterior midgut regions. Our data suggest that, in large part, strain‐specific effects of dietary glucose can be explained on the basis of alternate alleles at the mapP locus in different homozygous strains of flies.Levels of amylase RNA in tissue extracts of flies from an amylase‐null strain were also measured. Low levels were observed in both anterior and posterior midgut extracts. These were unresponsive to dietary conditions. © 1992 Wiley‐Liss, Inc.
The role of microtubules in contractile ring function
Authors: Conrad Abigail H. , Paulsen Avelina Q. , Conrad Gary W. 
Published: June 2005

AbstractDuring cytokinesis, a cortical contractile ring forms around a cell, constricts to a stable tight neck and terminates in separation of the daughter cells. At first cleavage, Ilyanassa obsoleta embryos form two contractile rings simultaneously. The cleavage furrow (CF), in the animal hemisphere between the spindle poles, constricts to a stable tight neck and separates the daughter cells. The third polar lobe constriction (PLC‐3), in the vegetal hemisphere below the spindle, constricts to a transient tight neck, but then relaxes, allowing the polar lobe cytoplasm to merge with one daughter cell. Eggs exposed to taxol, a drug that stabilizes microtubules, before the CF or the PLC‐3 develop, fail to form CFs, but form stabilized tight PLCs. Eggs exposed to taxol at the time of PLC‐3 formation develop varied numbers of constriction rings in their animal hemispheres and one PLC in their vegetal hemisphere, none of which relax. Eggs exposed to taxol after PLC‐3 initiation form stabilized tight CFs and PLCs. At maximum constriction, control embryos display immuno‐localization of nonextractable α‐tubulin in their CFs, but not in their PLCs, and reveal, via electron microscopy, many microtubules extending through their CFs, but not through their PLCs. Embryos which form stabilized tightly constricted CFs and PLCs in the presence of taxol display immuno‐localization of nonextractable α‐tubulin in both constrictions and show many polymerized microtubules extending through both CFs and PLCs. These results suggest that the extension of microtubules through a tight contractile ring may be important for stabilizing that constriction and facilitating subsequent cytokinesis. © 1992 Wiley‐Liss, Inc.
An autoradiographic time study during regeneration in fully differentiated Xenopus eyes
Authors: Underwood Lauren Wunsh , Ide Charles F. 
Published: June 2005

AbstractNasal one‐third sized fragments were created from fully differentiated larval Xenopus eyes (stage 47). At various times post‐surgery, animals were injected with tritiated thymidine. All animals were fixed 1 day post‐injection. Animals injected 1 day post‐surgery showed limited healing and thymidine labeling in the retina. In animals injected 1 week post‐surgery, heavy thymidine label was localized in the ventrotemporal retina in a “thickened” neuroepithelium internal to the extending pigmented retinal epithelium. In contrast, the dorsal retina showed no apparent extra labeling, but rather resembled normal ciliary margin. In animals injected 1 month post‐surgery, the eye fragment regained normal size and retinal layering, and the label was restricted to the ciliary margin. Regenerative growth associated with healing appeared to have been completed by this time.This extra cell division that occurs during the 1st month post‐surgery may underlie novel axonal targeting properties shown by nasal one‐third sized fragments. For example, these findings are consistent with the idea that pattern duplication of the visuotectal projection in nasal one‐third sized eye fragments occurs via intercalary cell division during healing and regeneration. © 1992 Wiley‐Liss, Inc.
In vitro allogeneic cytotoxicity in the solitary urochordate Styela clava
Authors: Kelly Karen L. , Cooper Edwin L. , Raftos David A. 
Published: June 2005

AbstractHemocytes from the solitary urochordate Styela clava can effect allogeneic cytotoxicity in vitro. Spectrophotometric and microscopic quantification of eosin‐y dye exclusion revealed significantly greater frequencies of cell death in allogeneic hemocyte cultures when compared to autogeneic controls. This cytotoxic response was characterized by 1) transient activity such that specific cytotoxicity could be detected for only 4 hours of culture though continued specific killing may have been obscured by spontaneous cell death; 2) a necessity for cellular interaction demonstrated by the elimination of allogeneic cytotoxicity in the absence of cell contact; 3) killing of multiple targets by effector cells due to high levels of response at low allogeneic ratios; 4) insensitivity to altered temperature; 5) increased cytotoxicity in the absence of autologous plasma; 6) an absence of xenogeneic reactivity; 7) the presence of three hierarchical levels (low, intermediate, and high) of response. These data reflect events involved in the recognition of allogeneic cellular determinants resulting in specific cytotoxicity effected by immunocompetent cells. Such in vitro recognition and cytotoxic recognition and cytotoxic reactivity may be responsible for adaptive reactions caused by histoincompatibility in solitary tunicates. © 1992 Wiley‐Liss, Inc.
Length regulation in the Dictyostelium discoideum slug is a late event
Authors: Breen Edmond J. , Eliott Susannah , Vardy Phil H. , White Angela , Williams Keith L. 
Published: June 2005

AbstractTime‐lapse video light microscopy was used to study the emergence and maturation of the migratory slug from a D. discoideum aggregate. The anterior part, the tip of this simple multicellular organism, establishes migration prior to the definition of the rear, and hence the length of the slug. It was found that newly formed slugs of wild‐type strain WS380B can reach lengths greater than 1 cm, yet mature slugs of this strain are rarely longer than 2–3 μmm. Often the tip extended out of the aggregation mound upon an arching pillar of cells. After the tip first touched the substratum, it commenced migration with a rapid succession of movement steps. Here we show that at the initiation of migration, a differential rate of cell movement along the developing slug axis results in a series of complicated changes, before the stable and mature shape of the slug is formed. Our results lead to new conclusions about D. discoideum slug formation and shape maintenance. Evidence is presesnted for regulation of slug length. © 1992 Wiley‐Liss, Inc.
Effect of slow and ultra‐rapid freezing on cell surface antigens of 8‐cell mouse embryos
Authors: Wood Maureen J. , Sjöblom Peter , Lindenberg Svend , Kimber Susan J. 
Published: June 2005

AbstractThe distribution of four cell surface antigens (SSEA‐1, SSEA‐3, SSEA‐4, and I) present on mouse preimplantation embryos was examined on 8‐cell stage embryos immediately after flushing from the reproductive tract and after slow or ultra‐rapid freezing. Frozen‐thawed and nonfrozen embryos were also examined after culture in vitro for 5, 24, or 48 h. Immediately after thawing, embryos showed a disruption in the polarity of cell surface antigens SSEA‐3, SSEA‐4, and I, but no differences were detected in fluorescence intensity or various other staining characteristics. No long‐term changes in the distribution of cell surface components were detected. Implantation and embryonic development were similar for frozen and nonfrozen embryos transferred to the uterine horns of pseudopregnant recipients. © 1992 Wiley‐Liss, Inc.
Effects of short‐term 17β‐estradiol treatment on the properties of T4‐binding proteins in the plasma of immature rainbow trout, Oncorhynchus mykiss
Authors: Cyr Daniel G. , Eales J. G. 
Published: June 2005

AbstractTo determine the effects of 17β‐estradiol (E2) on the properties of the plasma proteins that bind L‐thyroxine (T4), immature rainbow trout, Oncorhynchus mykiss, were injected intraperitoneally on days 0 and 3 with 0.5 mg E2‐3‐benzoate/100 g body weight, and plasma was sampled on days 4, 7, or 12. Control trout received peanut oil alone. E2 caused a small but significant decrease in the free T4 index. Saturation analysis on miniature G‐25 Sephadex columns revealed at least two major T4‐binding sites. Filtration on agarose Bio‐gel A 1.5 also indicated two major T4‐binding protein fractions with molecular weights of 150 and 55 kDa with a small proportion of T4 binding to a 1,500‐kDa site presumed to be lipoprotein. Addition of unlabeled T4 displaced [125I]T4 from the 55‐kDa site and unmasked an adjacent site of higher molecular weight. E2 increased the proportion of T4 bound to the low‐affinity (150 kDa) site relative to that bound to the high‐affinity (55 KDa site, increased the level of protein associated with the 1,500‐kDa site and its T4 binding, and also initiated the production of presumed vitellogenin (VTG), which bound a small amount of T4. It is concluded that the E2‐induced depression in FT4 is caused by a shift in T4 binding between high‐affinity and low‐affinity sites, and also by binding of small amounts of T4 to presumed lipoprotein and VTG. © 1992 Wiley‐Liss, Inc.
Regenerative responses in cultured hindlimb stumps of larval Xenopus laevis
Authors: Cannata Stefano M. , Bernardini Sergio , Filoni Sergio 
Published: June 2005

AbstractThe regenerative capacity of larval Xenopus laevis hindlimbs amputated through the tarsalia at different stages of development and explanted in vitro was tested. In the first experimental series hindlimb stumps from stage 53, 54, 55, and 57 larvae (according to Nieuwkoop and Faber, '56) were cultured in Leibovitz's L‐15 medium supplemented with 10% FCS, and 0.04 U of insulin and 10−8mg of L‐thyroxine per ml of medium. Results showed that the distal part of the limb stumps from stages 53, 54, and 55 formed a regeneration blastema composed of proliferating mesenchymal cells beneath a typical apical cap. No blastema was formed in the proximal part of the stump. In limb stumps from stage 57, a regeneration blastema did not form either in the proximal or in the distal part of the stump. In a second experimental series, hindlimb stumps from stage 55 larvae, denervated 5 days prior to amputation in order to eliminate any residual neurotrophic factor, were cultured in a simplified L‐15 medium containing 2% FCS and lacking insulin and thyroxine. Results showed that also in these experimental conditions the stumps from stage 55 formed a conical regeneration blastema at the distal tip. The blastema cells duplicated their own DNA and divided. At the proximal extremity no regeneration blastema was formed. In the same culture medium, the stumps of larvae at stage 57 did not form a regeneration blastema. Overall these results confirm those obtained in vivo on denervated and amputated limbs of larval Xenopus (Filoni and Paglialunga: Differentiation 43:10–19, 1990), namely, that the early stage limbs are able to form a regeneration blastema in the absence of nerves while the late stage limbs are nerve‐dependent for regeneration. The capacity of the early stage limbs for forming a regeneration blastema on the distal tip seems related to the presence, in the amputation area, of a population of undifferentiated mesenchymal cells capable of proliferating in the absence of mitogenous nerve factors. © 1992 Wiley‐Liss, Inc.
Intracellular pH regulation and metabolic interactions in hepatic tissues
Authors: Walsh Patrick J. , Mommsen Thomas P. 
Published: June 2005

AbstractIntracellular pH (pHi) regulation in the vertebrate liver relies heavily on ionic transport mechanisms. Liver, in common with many tissues, has plasma membrane Na+‐H+ and Cl−‐HCO3− electroneutral exchangers which work in opposition to tightly control pHi. Mammalian livers also possess electrogenic Na+‐HCO3 exchangers, capable of base uptake, which, when coupled to pHi‐mediated changes in membrane potential, probably confer an additional measure of pHi control, compared to fish livers, where the transporter appears to be functionally absent. It is suggested that this may be a fundamental difference between aquatic and aerial breathing. pHi regulation has barely been examined in invertebrate hepatic tissues, but already some interesting differences are apparent. Notably, an electrogenic 2Na+ ‐1H+ acid‐extrusion system is present in apical membranes of crustacean hepatopancreas. Despite these ionic control systems, complex acid‐base disturbances (e.g., “metabolic” acidosis) have been known for some time to influence hepatic metabolism in vertebrates, but few studies have carefully examined the independent effects of the acid‐base variables involved. Thus mechanistic explanations for the effects of acid‐base disturbances are scarce. Ureogenesis in mammals has been well studied, and several pH‐related mechanisms are evident. In contrast, the pH‐insensitivity of ureogenesis in fish liver may represent a second difference between aquatic and terrestrial species. In summary, by virtue of its metabolic diversity, liver represents a potentially important organ in acid‐base balance, and an interesting study tissue for interrelationships between metabolism and acid‐base balance. © 1992 Wiley‐Liss, Inc.