bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of LH‐induced and spontaneous meiotic maturation in mouse oocytes by Nα‐tosyl‐L‐lysine chloromethylketone
Authors: Hashimoto Naohiro , Kishimoto Takeo , Nagahama Yoshitaka 
Published: June 2005

AbstractThe effect of Nα‐tosyl‐L‐lysine chloromethylketone (TLCK), an inhibitor of trypsin‐type proteases, on luteinizing hormone (LH)‐induced and spontaneous meiotic maturation and follicular production of cAMP in mice was determined. When follicle‐enclosed mouse oocytes were incubated with LH (1μg/ml), they underwent the breakdown of the germinal vesicle (GVBD). TLCK (0.02–0.5 mM) inhibited LH‐induced GVBD in folliculated oocytes. The concentration (0.5 mM) of TLCK that inhibited LH‐induced GVBD did not significantly suppress LH‐induced cAMP production by follicle cells.The effect of TLCK on spontaneous maturation in cumulus cell‐enclosed and denuded oocytes was also determined. TLCK strongly inhibited spontaneous maturation in denuded oocytes only if it was added to the incubation medium for 1–3 h before oocytes were liberated from the follicular tissue. The inhibition of oocyte maturation by TLCK was significantly greater in cumulus cell‐enclosed oocytes than in denuded oocytes, either with or without preincubation with TLCK. These results suggest that trypsin‐type protease in oocytes participates in the process of meiotic maturation in mouse oocytes.
Nuclear basic proteins in mature testis of the ascidian tunicate Styela montereyensis
Authors: Chiva M. , Rosenberg E. , Kasinsky H. E. 
Published: June 2005

AbstractWe have studied the basic protein content of nuclei in mature testis of the hermaphroditic, solitary ascidian tunicate Styela montereyensis. Cytochemically, tunicate sperm nuclei stain in a manner similar to that of the mussel Mytilus, indicating the presence of type 3 intermediate sperm basic proteins in the classification scheme of Bloch (Genetics [supplement] 61:93–111, 1969). Biochemically, these sperm nuclei possess basic proteins that are very rich in arginine (ca. 50 mole %) and moderately rich in lysine (ca. 17 mole %). These basic proteins are therefore protamines according to the definition of Subirana (The Sperm Cell, Martinus Nijhoff BV, The Hague, pp. 197–213, 1983). These protamines replace either the major part or all of the somatic histones in the testis. The very lysine‐rich H1 histones of S. montereyensis testis, some of which are also rich in arginine (22 mole %), display a number of electrophoretic components with varying mobilities. Comparing these characteristics of the sperm basic proteins in S. montereyensis with those in echinoderms and vertebrates indicates some similarities to each of these deuterostome phyla representing distinct evolutionary lines. Thus, the presence of arginine‐rich protamines in S. montereyensis and the displacement of somatic histones in sperm nuclei by these protamines are typical of many vertebrate species. Variation in the H1 family of very lysine‐rich histones in S. montereyensis testis, including some H1 histones with an elevated arginine content, can also be seen in many echinoderms.
Molecular homology of coexpressed eye‐ and liver‐specific lactate dehydrogenase isozymes from the basketmouth cichlid assessed by oxamate‐Sepharose and blue dextran‐Sepharose affinity chromatography
Authors: Leibel Wayne S. , Peairs Kimberly S. 
Published: June 2005

AbstractRecently, several teleost fishes (Perciformes, Cichlidae) have been found that coexpress both a cathodal, liver‐specific and an anodal, eye‐specific lactate dehydrogenase (LDH), and evidence supporting the hypothesis that these are the products of two distinct genes has been presented (Holt and Leibel, '87). In this study, the molecular homology of these two isozymes from the basketmouth cichlid, Acaronia nassa, relative to each other and to eye‐specific and liver‐specific isozymes from a variety of other fishes is assessed by oxamate‐Sepharose and blue dextran‐Sepharose affinity chromatography. Whereas the eye‐specific isozyme from the basketmouth cichlid and all other LDHs from a variety of vertebrates bound tightly to the oxamate column in the presence of the cofactor NADH, the liver‐specific isozyme from basketmouth, and the testes‐specific LDH‐X from rat failed to bind. Similarly, the liver‐specific isozyme from basketmouth failed to bind to the blue dextran column, whereas the liver‐specific C4 from goldfish (Cypriniformes) bound and eluted with NADH; the eye‐specific C4 from three cichlids, including the basketmouth, and rat testis‐specific LDH‐X bound and eluted with NAD+. These results suggest that the eye‐ and liver‐specific LDH isozymes from the basketmouth cichlid are not encoded by the same locus and that this liver‐specific isozyme is very different from analogous isozymes that occur in various Cypriniform and Gadiform fishes.
Phosphofructokinase in the mantle of the sea mussel Mytilus galloprovincialis Lmk.
Authors: Villamarin J. A. , Rodriguez‐Torres A. M. , Ibarguren I. , Ramos‐Martinez J. I. 
Published: June 2005

AbstractPhosphofructokinase (PFK) from the mantle of Mytilus galloprovincialis Lmk. was purified 302‐fold with a yield of 27%. The enzyme proved to be a 340,000‐dalton oligomer comprising four identical 85,000‐dalton subunits.Like other phosphofructokinases, the enzyme behaved cooperatively with fructose 6‐phosphate and was inhibited by high concentrations of ATP.The fall in pH value produces a decrease of enzyme affinity for Fru 6‐P and for the activator AMP, together with a greater inhibition by ATP.AMP, cyclic AMP, and fructose 2,6‐bisphosphate increased the affinity of mussel mantle PFK for Fru 6‐P and decreased the inhibition by ATP, while ammonium ions activated the enzyme increasing only the Vmax. Phosphoenolpyruvate acted as an inhibitor, decreasing the affinity of the enzyme for Fru 6‐P.
Avian vasculogenesis and the distribution of collagens I, IV, laminin, and fibronectin in the heart primordia
Authors: Drake Christopher J. , Davis Lynn A. , Walters Luanne , Little Charles D. 
Published: June 2005

AbstractThe heart‐forming regions of the early embryo are composed of splanchnic mesoderm, endoderm, and the associated ECM. The ECM of the heart‐forming regions in stage 7–9 chicken embryos was examined using immunofluorescence. Affinity purified antibodies to chicken collagens type I and IV, chicken fibronectin, and mouse laminin were used as probes. We report that (1) the basement membrane of the endoderm contains immunoreactive laminin and collagen IV; (2) the nascent basement membrane of the heart splanchnic mesoderm contains immunoreactive laminin, but not type IV collagen, and (3) the prominent ECM between the splanchnic mesoderm and the endoderm (the primitive‐heart ECM) contains collagen IV, collagen I, fibronectin, but not laminin. In addition, we describe microscopic observations on the spatial relationship of cardiogenic cells to the primitive‐heart ECM and the endodermal basement membrane.
Seasonality in plasma thyroxine binding in turtles
Authors: Licht Paul , Denver Robert J. , Pavgi Sushama , Herrera Brenda 
Published: June 2005

AbstractThe relation between seasonal changes in plasma thyroxine (T4) and T4 binding activity was studied in three species of turtle previously shown to differ in the nature of their binding proteins; additional direct measurements of a high affinity T4 binding protein (TBP) were made in one species using RIA. In the painted turtle, Chrysemys picta (Family Emydidae), a species with large seasonal changes in plasma T4, the binding protein measured by activity and RIA showed significant seasonality. Binding activity correlated with direct estimates of TBP by RIA. TBP was minimal upon emergence from hibernation and maximal in late summer (July–August), about a month after the peak in plasma T4. In contrast, two other nonemydid species, the green turtle (Chelonia mydas) and Mexican tortoise (Gopherus flavomarginatus) showed relatively low plasma T4 and binding activity with no significant seasonality in either. Electrophoretic studies (PAGE) confirmed that T4 binding in C. picta is almost wholly associated with a high affinity, low capacity TBP; whereas, it is confined to high capacity sites (probably albumin) in the other species. The transport of T4 is clearly handled differently in these three turtles. In the green turtle and tortoise, one would expect relatively constant free T4 (fT4) throughout the year. Marked seasonal fluctuations (an order of magnitude) in the ratios of TBP to total T4 in C. picta due to the temporal lag between the two may cause profound changes in fT4 with peaks in late spring.
Defensive function of trichocysts in Paramecium
Authors: Harumoto Terue , Miyake Akio 
Published: June 2005

AbstractA putative defensive function of trichocysts in Paramecium has been tested experimentally. Cells of trichocyst‐non‐discharge (tnd) mutant, artificially induced trichocyst‐deficient cells, and intact wild‐type cells were compared as prey for a carnivorous ciliate, Dileptus margaritifer. Cells of tnd mutants were eaten 9–45 times faster than wild‐type cells by the predator in P. caudatum and P. tetraurelia. Encounters between paramecia and dilepti occurred in nearly the same frequency in mutant and wild‐type cells. Paramecia with reduced numbers of trichocysts were obtained in P. caudatum, P. jenningsi, and P. tetraurelia by treating wild‐type cells with lysozyme, an inducer of trichocyst discharge. These cells were eaten faster than intact cells by the predator and the rate of predation was inversely correlated with the remained capacity of trichocyst discharge. It was concluded that the discharge of trichocysts defends these species of Paramecium against D. margaritifer. Therefore, the results of this work strongly support the hypothesis that trichocysts in Paramecium function as defensive organelles against predators. The results also support the hypothesis that the offense‐defense interaction between Dileptus and Pramecium is mediated by their extrusomes (toxicysts and trichocysts) and suggest that extrusomes in ciliates function as organelles for interspecific cell‐cell interaction.
Sexing of rat embryos with antisera specific for male rats
Authors: Utsumi Kyozo , Satoh Eisuke , Iritani Akira 
Published: June 2005

AbstractMale‐specific antigenicity (H‐Y antigen) of rat embryos has been examined, and the feasibility of sexing rat embryos by use of H‐Y antibodies has been studied. Rat H‐Y antisera were produced by immunization of female Wistar rats with a homogenate of testes from male Wistar neonates. Male specificity of the antiserum (H‐Y antibody) was determined by retention of cytoxicity to male epidermal cells after absorption with female cells. After cultivation of rat embryos for 5 to 6 hr in the presence of antibody, half of the embryos were arrested at the morula stage. However, these embryos developed into blastocysts after removal of the antiserum, and then they grew into male young in recipient foster mothers. Eighty percent of the embryos that developed to blastocysts in the presence of the antiserum grew into female young.
Progression of Oocyte Maturation From Metaphase I to Metaphase II is disturbed by previous immunological interference with cumulus cell function
Authors: Tesarik Jan , Lefèvre Brigitte , Testart Jacques 
Published: June 2005

AbstractThe effects of an antibody preparation reacting with preovulatory mouse cumuli oophori (anticumulus Ig) on oocyte maturation in vivo and in vitro were studied. Continuous presence of anticumulus Ig in culture medium did not impair oocyte maturation in vitro. Similarly, no effect on oocyte maturation in vivo was observed when anticumulus Ig was given to females superovulated with pregnant mare serum gonadotopin (PMSG) and human chorionic gonadotropin (hCG) at the time of hCG treatment. However, when administered earlier, anticumulus Ig brought about serious disturbances of oocyte meiotic competence, since only immature oocytes were ovulated after anticumulus Ig injection at the time of PMSG treatment and as much as 70% of the ovulated oocytes were immature when the antibody was applied 24 hr later. Previous absorption of anticumulus Ig with isolated cumulus cells removed the inhibitory effect of this preparation on oocyte meiotic competence to the same extent as absorption with whole cumuli oophori, despite the persistence of a strong reactivity of the cumulus cell‐absorbed antibody preparations with the cumulus intercellular matrix. The ability of oocytes obtained from antibody‐injected animals to mature in vitro was also considerably impaired when the injection was made at the time of PMSG treatment. In all cases the maturation defect concerned the progression of meiosis from metaphase I to metaphase II, while the ability of oocytes to undergo germinal vesicle breakdown (GVBD) was unchanged. It is concluded that (1) the competence of oocytes to progress from metaphase I to metaphase II of meiosis can be subject to an isolated alteration without any disturbance of GVBD, (2) the cumulus cells sustain the development of the oocyte competence to effect the metaphase I–metaphase II transition, and (3) this activity of cumulus cells is limited in time and coincides with the PMSG action in the standard superovulation regimen.
Oocyte recovery and maturation in the American black bear (Ursus americanus): A model for endangered ursids
Authors: Johnston L. A. , Donoghue A. M. , Igo W. , Simmons L. G. , Wildt D. E. , Rieffenberger J. 
Published: June 2005

AbstractA study was conducted to determine if meiotic maturation could be induced in ovarian oocytes of the American black bear (Ursus americanus), a model for gamete “rescue” techniques for endangered ursids. Ovaries obtained from 48 black bears yielded 2,403 oocytes (51.1 ± 4.9/female), of which 777 (32.3%) were morphologically classified as excellent quality. More total oocytes were recovered from donors that were anestrous compared to luteal/pregnant (P < 0.05) at the time of ovarian excision. Delaying the recovery of oocytes from antral follicles within excised ovaries from 12–24 hr to 25–36 hr had no effect (P > 0.05) on the overall number of high quality oocytes recovered or subsequent maturational ability. The highest incidence of metaphase II was reached between 48 and 60 hr of in vitro incubation. Donor status (anestrous vs. luteal/pregnant) had no influence on the oocyte maturation rate by 24 or 48 hr, but by 60 hr, more (P < 0.05) oocytes recovered from anestrous females (43.9%) had achieved metaphase II compared to luteal/pregnant counterparts (23.1%). In preliminary trials involving endangered ursids, 54 ovarian oocytes were recovered from three aged sun bears (Helarctos malayanus), of which 72.2% were excellent quality and 15.4% matured in vitro to metaphase II. Similarly, 119 antral oocytes were recovered from two aged sloth bears (Melursus ursinus), of which 41.2% were excellent and 17.5% matured in vitro. These results demonstrate that: (1) ursid oocytes undergo nuclear maturation in vitro; (2) reproductive status of the donor influences the total number and maturational ability of recovered oocytes; and (3) preliminary observations suggest the American black bear to be a useful model for developing oocyte rescue techniques for related but endangered species. © Wiley‐Liss, Inc.
Small cardioactive peptide B increases the responsiveness of the neural system underlying prey capture reactions in the pteropod mollusc, Clione limacina
Authors: Norekian Tigran P. , Satterlie Richard A. 
Published: June 2005

AbstractEffects of small cardioactive peptide B (SCPB) on cerebral neurons which underlie prey capture in the carnivorous pteropod mollusc, Clione limacina, were investigated. SCPB in concentrations of 10 μM and higher produced direct activation of cerebral ganglion neurons underlying extrusion of buccal cones used in prey capture. SCPB in lower concentrations, between 1 and 5 μM, did not have a noticeable effect on the membrane potentials of these neurons; however, it significantly increased their responsiveness to sensory inputs from the tactile stimulation of the head, and their ability to generate afterdischarge activity.SCPB immunoreactivity was observed in cell bodies in buccal, cerebral, pedal, and intestinal ganglia, as well as in the anterior esophagus and in buccal cones where fibers stained intensely. These electrophysiological and immunohistochemical data suggest that SCPB may have a physiological role in feeding arousal in Clione. © 1994 Wiley‐Liss, Inc.
TGFβ1 regulation of collagen metabolism by embryonic palate mesenchymal cells
Authors: D'Angelo Marina , Chen Jing‐May , Ugen Kenneth , Greene Robert M. 
Published: June 2005

AbstractProper metabolism of the extracellular matrix (ECM) in mammalian embryonic palatal tissue is required for normal development of the palate. In particular, perturbation of collagen metabolism in the embryonic orofacial region results in the production of cleft palate. Although several types of collagen have been localized in the embryonic palate, factors responsible for regulating their synthesis have not been identified. Transforming growth factor β (TGFβ), shown to be capable of modulating ECM metabolism in other tissues, has been localized in the developing palate. Thus, we examined the ability of TGFβ1 to modulate collagen synthesis and degradation in murine embryonic palate mesenchymal (MEPM) cells in vitro.Immunohistochemical analysis confirmed that type III collagen was predominant in the mesenchyme of the embryonic palate, whereas type I collagen was ubiquitous throughout palatal epithelium and mesenchyme. Total collagen production by TGFβ‐treated confluent MEPM cells in serum‐free conditioned medium was determined by measuring incorporation of L‐[2‐3‐4‐5‐3H]‐proline into hydroxyproline. Treatment for 24 hr with TGFβ1 stimulated incorporation into both cell layer and medium fractions. Quantification of collagen types by ELISA indicated that TGFβ1 stimulated the accumulation of type III collagen as early as 3 hr after treatment. Northern blot analysis of MEPM cells treated with TGFβ1 revealed that steady‐state levels of mRNA encoding for procollagen α1(I) and α1(III) were increased and that these effects were ablated by cycloheximide but not actinomycin. The effects of TGFβ treatment on MEPM cell collagen levels also reflected alterations in collagen degradation. TGFβ‐treated MEPM cells exhibited a significant diminution of total protease activity. Moreover, analysis by substrate gel electrophoresis indicated specific decreases in vertebrate collagenase and stromelysin. These data represent the first report of changing proteolytic profiles during palatogenesis. Thus, TGFβ regulates the amount of collagen present in embryonic palatal tissue at the level of synthesis and degradation. © 1994 Wiley‐Liss, Inc.
Brief treatment with an aromatase inhibitor during sex differentiation causes chromosomally female salmon to develop as normal, functional males
Authors: Piferrer Francesc , Zanuy Silvia , Carrillo Manuel , Solar Igor I. , Devlin Robert H. , Donaldson Edward M. 
Published: June 2005

AbstractAlthough many studies implicate sex steroids in the process of sexual differentiation, the exact role played by these substances in lower vertebrates, especially teleost fish, is not clear, since it is not conclusively known whether sex steroids are the cause or an early consequence of sex differentiation. By hormonal manipulation and specific crossings, it is possible to produce all‐female stocks of the otherwise gonochoristic chinook salmon (Oncorhynchus tshawytscha). These all‐female stocks are an excellent model to study the effects of steroids on sexual differentiation since the genetic sex is known before the actual differentiation of the embryonic gonads takes place. In the present study, we show that treatment with a nonsteroidal inhibitor of aromatase, the enzyme that catalyzes the conversion from androgens to estrogens, for only 2 hours when the gonads were bipotent, caused genetic females to develop into normal males. Furthermore, these males had testes which were indistinguishable both in size and in structure from those of genetic males, and completed all the stages of spermatogenesis. At 2 years of age, these males produced viable sperm capable of inducing normal embryonic development when used to fertilize eggs, with a resulting all‐female progeny. These results provide strong support for Yamamoto's theory (Yamamoto, '69) that androgens and estrogens are natural sex inducers in gonochoristic fish, and suggest that aromatase plays a pivotal role in the sex differentiation of salmon. Thus, by brief treatment with an aromatase inhibitor at a specific time in development, an organism was induced to develop a funtional, phenotypic sex different from its genetic sex. © 1994 Wiley‐Liss, Inc.
Evidence for a developmental and evolutionary link between placodal ectoderm and neural crest
Authors: Smith Steven C. , Graveson Ann C. , Hall Brian K. 
Published: June 2005

AbstractThe premature death (p) mutation in the Mexican axolotl (Ambystoma mexicanum) affects the ability of ectoderm to produce normal neural crest cells. We have examined the effect of this mutation on the development of a derivative of placodal ectoderm—the lateral‐line system—and found that both migration of lateral‐line primordia and differentiation of mechanoreceptive neuromast organs are disrupted in p/p embryos. These effects cannot be explained by the presence of other mutant tissues, since development is also abnormal when lateral‐line placodes from mutant embryos are transplanted into wild‐type hosts. Furthermore, wild‐type placodes develop normally in mutant embryos. Thus, the p gene affects both placodal and neural crest cell development. These results strongly suggest that neural crest cells and placodal ectoderm arise in response to common developmental interactions, which could indicate that they were derived from an ancestral precursor tissue. © 1994 Wiley‐Liss, Inc.
Long‐lasting, sex‐specific inhibition of serotonin‐induced spawning by methiothepin in the zebra mussel, Dreissena polymorpha (Pallas)
Authors: Fong Peter P. , Hardege Jorg D. , Ram Jeffrey L. 
Published: June 2005

AbstractZebra mussels (Dreissena polymorpha) can be stimulated to spawn with external application of serotonin. Inhibition of serotonin‐elicited spawning by methiothepin, a serotonin receptor ligand, was investigated. Methiothepin, which inhibits both male and female spawning when present concomitantly with serotonin (Fong et al. [1994a]) was demonstrated to cause long‐lasting inhibition of spawning in females for up to 12 days after its application. Mussels were exposed to various concentrations of methiothepin for 5 hours, rinsed with fresh water, and then tested with 10−3 M serotonin on the next day. Spawning in females that had been exposed to 10−5 M methiothepin was completely blocked, with little effect on male spawning. At methiothepin concentrations as low as 10−8 M, spawning latency in response to serotonin was significantly increased in females; higher concentrations also increased spawning latency in males. Exposure to 10−5 M methiothepin for as little as 30 minutes was sufficient to completely inhibit spawning in females, but not in males. A 21‐hour exposure to either 10−6 or 10−5 M methiothepin also significantly inhibited female spawning, with much smaller effects on males. Percent spawning in different groups of animals tested 1,2,4,8, and 12 days after a 5‐hour exposure to 10−5 M methiothepin was significantly reduced for females on all test days, but not for males. The mechanisms of this sex‐specific and long‐lasting inhibition of serotonin‐induced spawning are discussed with reference to receptor binding, retention, toxicity, and partial agonist properties of methiothepin. © 1994 Wiley‐Liss, Inc.