bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prolyl 4‐hydroxylase in the foot of the marine mussel Mytilus edulis L.: Purification and characterization
Authors: Marumo Keishi , Waite J. Herbert 
Published: June 2005

AbstractThe mussel foot secretes a variety of unusual hydroxyproline‐containing collagenous and noncollagenous proteins. Prolyl 4‐hydroxylase acting on one or more of the secreted proteins was isolated from the foot by using conventional gel filtration and ion exchange chromatography. Mr of the intact enzyme was 230,000 (α2β2) composed of two subunits with Mr of 60,000 (α) and 57,000 (β) as estimated by HPLC gel filtration and SDS‐PAGE. The enzyme utilized (Pro‐Pro‐Gly)10 as a substrate with an apparent Km value of 0.17 mM. Cofactors and inhibitors were very similar to animal, plant, and microbial prolyl hydroxylases previously described. The enzyme had a relatively sharp pH optimum in the range of 7.8–8.3 and the hydroxyproline formed increased in proportion to the rise in the temperature between 5 and 20°C. No detectable hydroxylation occurred with poly‐L‐proline or the unhydroxylated decapeptide analog (Ala‐Lys‐Pro‐Ser‐Tyr‐Pro‐Pro‐Thr‐Tyr‐Lys) of the polyphenolic protein. Kinetic studies, however, revealed that the mussel prolyl 4‐hydroxylase was competitively inhibited by poly‐L‐proline and uncompetitively inhibited by the decapeptide. These results suggest that the decapeptide binds the enzymesubstrate i.e. (Pro‐Pro‐Gly)10 complex. It is not yet clear whether this enzyme acts exclusively on collagenous substrates or whether its catalytic purview extends as well to the polyphenolic protein.
Hyperosmotic cellular volume regulation in the ribbed mussel Geukensia demissa: Inhibition by lysosomal and proteinase inhibitors
Authors: Deaton Lewis E. 
Published: June 2005

AbstractThe microbial proteinase inhibitors bestatin, leupeptin, chymostatin, antipain, and pepstatin (all at 10−4 M) inhibit the proteolytic activity of gill homogenates of the ribbed mussel Geukensia demissa by 20–30%. In combination, these inhibitors reduced the hydrolysis of casein by 50%.Isolated gills from G. demissa acclimated to 500 mOsm seawater (SW) were incubated in 1000 mOsm SW for 8 h in the presence of the following proteinase and lysosome inhibitors: bestatin, pepstatin, leupeptin, antipain, chymostatin, NH4Cl, imidazole, and chloroquine. In control tissues the amino acid pool increased by 155 μmol/g dry wt. Imidazole (10 mM), NH4Cl (10 mM), and chloroquine (10−4 M) inhibited this increase by 70, 60, and 50%, respectively. Pepstatin, bestatin, and leupeptin (all 10−4 M) also inhibited the accumulation of amino acids in gills exposed to higher ambient salinity by 30–40%. In combination, these three microbial proteinase inhibitors reduced the enlargement of the amino acid pool by 60%. Chymostatin and antipain had no effect on the increase in the amino acid content of the tissues.The effects of these inhibitors on the amino acid levels of gill tissues incubated in isomotic seawater were minor. None of the inhibitors had significant effects on the oxygen uptake of isolated gills.The results from gills exposed to the amines and chloroquine suggest that lysosome‐mediated proteolysis is involved in the accumulation of alanine and glycine during cellular adjustment to hyperosmotic stress in marine bivalves. The effectiveness of pepstatin, leupeptin, and bestatin in reducing this accumulation implicates aminopeptidase I and cathepsins B and D as the specific enzymes involved in the proteolysis associated with adjustment to hyperosmotic stress.
Studies on the mechanisms of neurulation in the chick: Morphometric analysis of force distribution within the neuroepithelium during neural tube formation
Authors: Nagele Robert G. , Hunter Edward , Bush Kevin , Lee Hsin‐Yi 
Published: June 2005

AbstractChanges in the shape of neuroepithelial cells, particularly apical constriction, are generally thought to play a major role in generating the driving forces for neural tube formation. Our previous study [Nagele and Lee (1987) J. Exp. Zool., 241:197–205] has shown that, in the developing midbrain region of stage 8+ chick embryos, neuroepithelial cells showing the greatest degree of apical constriction are concentrated at sites of enhanced bending of the neuroepithelium (i.e., the floor and midlateral walls of developing neural tube), suggesting that driving forces resulting from apical constriction are concentrated at these sites during closure of the neural tube. In the present study, we have used morphometric methods to 1) measure regional variations in the degree of apical constriction and apical surface folding at selected regions along the anteroposterior axis of stage 8+ chick embryos, which closely resemble the various ontogenetic phases of neural tube formation, and 2) investigate how forces resulting from apical constriction are distributed within the neuroepithelium during transformation of the neural plate into a neural tube. Results show that, during neural tube formation, driving forces resulting from apical constriction are not distributed uniformly throughout the neuroepithelium but rather are concentrated sequentially at three distinct locations: 1) the floor (during transformation of the neural plate to a V‐shaped neuroepithelium), 2) the midlateral walls (during transformation of the V‐shaped neuroepithelium into a C‐shaped neuroepithelium), and 3) the upper walls (during the transformation of the C‐shaped neuroepithelium into a closed neural tube).
Secondary sex characteristics and connected physiological values in male fallow deer (Dama dama L.) and their relationship to changes of the annual photoperiod: Doubling the frequency
Authors: Schnare H. , Fischer K. 
Published: June 2005

AbstractFive male fallow deer, who were at the time of casting their first antlers, were maintained in a barn with artificial light control. The daylength sequence applied simulated an amplitude which was normal for 52° latitude, but each cycle lasted only 6 months. This photoperiod produced a doubling in frequency of morphogenetic and connected physiological values so that three complete antler cycles were reached within 19 months. Increase in levels of alkaline phosphatase and in concentrations of total‐cholesterol (TC) and low‐ and high density lipoprotein cholesterol (LDL‐C and HDL‐C) followed the frequency of light alterations and correlated well with antler formation. On the other hand, an increase in neck circumference as well as increase of creatinine levels correlated well with the hard antler period of fertility as well.
Eye regeneration in the mystery snail
Authors: Bever Michele Miller , Borgens Richard B. 
Published: June 2005

AbstractMystery snails (Family Ampullariidae) are aquatic prosobranchs which possess structurally complex eyes at the tip of a cephalic eyestalk. No other sensory organs are found in association with this stalk. These snails possess the ability to regenerate the eye completely after amputation through the mid‐eyestalk. Amputation induces gross changes in the cellular character of the entire eyestalk; in particular, an invagination of integumentary epithelium at the apex of the eyestalk stump produces a shallow cleft or “eyecup.” Differentiation of all components of the eye apparently occurs by transdetermination of these epithelial cells. Retinal differentiation and the appearance of a new lens is observed as soon as 14 days postamputation. Complete eyes (by external observation), although smaller than the originals, have regenerated by 25 days postamputation. We compare this regeneration to the reconstruction of other animal tissues, in particular the regeneration of amphibian limbs.
Evidence for the sexual bipotentiality of spermatogonia in the fish, Oryzias latipes
Authors: Shibata Naoki , Hamaguchi Satoshi 
Published: June 2005

AbstractThe origin of the oocyte‐like cells (testis–ova) induced by the administration of estradiol in the testis of the fish, Oryzias latipes, was examined by light and electron microscopy. A small number of testis–ova at the zygotene stage was seen on the sixth day after the beginning of treatment with estradiol, and on the 12th day testis–ova at the pachytene and diplotene stages were observed. Ultrastructural observations revealed that the testis–ova at the zygotene stage were organized as cysts and that all testis–ova within a given cyst developed synchronously. The number of these testis–ova in each cyst varied but cysts containing 16–20 or 26–30 testis–ova were most frequently observed. Spermatogonia of O. latipes are classified morphologically into two types: the type A and the type B Spermatogonia (Grier, '76 Cell Tissue Res., 168:419–431). Type A spermatogonia, which were separated from each other by Sertoli cells, were of the stem type and type B Spermatogonia appeared to divide clonally 9–10 times in each cyst before entering meiosis. The present observations on zygotene testis–ova indicate that the testis–ova originate from type B Spermatogonia which have divided clonally four or five times, suggesting that male germ cells remain sexually bipotent through the early stages of development of type B Spermatogonia.
Induction of maturation in cumulus cell‐enclosed mouse oocytes by follicle‐stimulating hormone and epidermal growth factor: Evidence for a positive stimulus of somatic cell origin
Authors: Downs Stephen M. , Daniel Susan A. J. , Eppig John J. 
Published: June 2005

AbstractThe efficacy of follicle‐stimulating hormone (FSH), epidermal growth factor (EGF), and dibutyryl cGMP (dbcGMP) as inducers of germinal vesicle breakdown (GVBD) in cumulus cell‐enclosed mouse oocytes was examined when meiotic arrest was maintained in vitro with purines, dibutyryl cAMP (dbcAMP), or the phosphodiesterase inhibitor, 3‐isobutyl‐1‐methylxanthine (IBMX). When FSH was added to hypoxanthine (HX)‐containing medium, the effect on oocyte maturation was at first inhibitory and later stimulatory. EGF stimulated GVBD at all time points tested. FSH and EGF also induced GVBD when oocytes were arrested with dbcAMP, IBMX, or guanosine. Dibutyryl cGMP stimulated GVBD when meiotic arrest was maintained with HX, but not when oocytes were meiotically arrested with guanosine, and was inhibitory in dbcAMP‐supplemented medium. FSH and dbcGMP produced a transient delay of oocyte maturation in control medium, but the FSH effect was much more pronounced. EGF had no effect on maturation kinetics. The actions of FSH and EGF required the presence of cumulus cells. Both agents significantly stimulated cAMP production in oocyte‐cumulus cell complexes. A brief exposure of complexes to a high concentration of dbcAMP induced GVBD, suggesting that FSH and EGF may act via a cAMP‐dependent process. The frequency of FSH‐ and EGF‐induced GVBD in cumulus cell‐enclosed oocytes was significantly higher than the frequency of GVBD when oocytes were cultured while denuded of cumulus cells. Thus, the induction of maturation is apparently not mediated solely by oocyte‐cumulus cell uncoupling and termination of the transfer of an inhibitory meiotic signal from cumulus cells to the oocyte. The data suggest the generation of a positive signal within cumulus cells in response to hormone treatment that acts upon the oocyte to stimulate GVBD in the continued presence of inhibitory factors.
Development of golden hamster embryos through the two‐cell block in chemically defined medium
Authors: Schini Scott A. , Bavister Barry D. 
Published: June 2005

AbstractThe effect of increasing the embryo:medium volume ratio on overcoming the hamster two‐cell block was examined. Two‐cell golden hamster embryos from each superovulated female were cultured in microdrops (estimated at 0.75 μ1) or 100 μl macrodrops of chemically defined medium (modified Tyrode's solution [TLP] plus glutamine, isoleucine, methionine, phenylalanine, and taurine). In 11 trials (i.e., with embryos from 11 donors), 28.6% of 269 embryos developed to the four‐cell stage in microdrops, whereas only 2 (0.7%) embryos developed in the macrodrops. When two microdrops were used to culture the two‐cell embryos from each donor (n = 8), 17.8% of 304 embryos developed to four cells. Increasing the embryo:medium volume ratio further by culturing all of the embryos from each donor (n = 10) in single microdrops resulted in 53.1% of 397 embryos developing to four cells. Conditioning of the culture medium by these embryos could not be demonstrated. Increasing the embryo:medium volume ratio may protect against loss of some intracellular component essential for growth of early‐stage hamster embryos. Alternatively, increasing this ratio may permit embryos to reduce the concentration of a substance detrimental to their growth. This work represents the first report of cleavage of hamster two‐cell embryos in vitro. These findings are a significant step towards our goal of obtaining complete preimplantation developmental of hamster embryos in vitro and may be helpful for solving the in vitro developmental blocks in embryos from other species.
Gonadotropin action on androgen synthesis in short‐term incubation of explants and dispersed cells of the testis of Xenopus laevis
Authors: Lecouteux Alain 
Published: June 2005

AbstractTestis cells of the toad Xenopus laevis were dissociated with collagenase and the cell suspension was enriched for steroidogenic cells by Percoll gradients. Results suggested that cells should be preincubated during a 6‐h period before stimulation with gonadotropin. Our results indicate that a 2‐h incubation period with gonadotropin was necessary to obtain a significant response. Furthermore, the cells can be maintained in a functional state longer than mammalian testis cells. Different gonadotropins were used to stimulate androgen production, and their effects were compared in both dissociated cells and testicular explants. Cells were more sensitive to luteinizing hormone (LH) and follicle stimulating hormone (FSH) than the explants (ED50 LH = 0.041 ± 0.003 μg for cells and 0.097 ± 0.002 μg for explants: ED50 FSH = 0.41 ± 0.03 μg for cells and 0.63 ± 0.03 μg for explants). Moreover, human chorionic gonadotropin (hCG) which only stimulates testicular explants at high doses, failed to stimulate the androgen production of dissociated cells; this indicates a low sensitivity of amphibian testis to hCG and a possible damaging effect of collagenase on the receptors of isolated cells.
Thyrotropic activity of salmon pituitary glycoprotein hormones in the Hawaiian parrotfish thyroid in vitro
Authors: Swanson Penny , Grau E. Gordon , Helms Lisa M. H. , Dickhoff Walton W. 
Published: June 2005

AbstractThe thyrotropic activities of salmon pituitary extract, thyroid‐stimulating hormone (TSH), gonadotropins (GTH), and glycoprotein fractions obtained during purification of salmon TSH and GTH were measured using the parrotfish thyroid culture system. Purified salmon TSH was approximately 1,000 times more potent than bovine TSH in stimulating thyroxine release into the culture medium. Most of the forms of salmon GTH had no thyrotropic activity. One of the forms of salmon GTH (GTH‐F) and three chromatofocusing fractions (CF‐B, ‐C, and ‐E) that were devoid of activity in the coho salmon in vivo had some thyrotropic activity in the parrotfish thyroid culture. Whether the activity of these fractions was due to contamination with TSH, less potent forms of TSH, or inherent thyrotropic activity of a form of GTH is discussed. These results indicate that the parrotfish thyroid culture system can be used to detect thyrotropic activity of fractions obtained during the purification of teleost TSH.
Histochemical and biochemical characterization of two slow fiber types in decapod crustacean muscles
Authors: Mykles Donald L. 
Published: June 2005

AbstractMyofibrillar proteins in muscles of the claws and abdomen of lobster, Homarus americanus, and the claws of fiddler crab, Uca pugnax, and land crab, Gecarcinus lateralis, have been analyzed with sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. Fibers contained numerous isoforms of structural and regulatory proteins in assemblages correlated with fiber type. One fast (F) and two slow (S1 and S2) fibers were identified. All F fibers possessed two isoforms of paramyosin (P1 and P2), while all slow fibers, with the exception of Uca major claw, contained only the P2 variant. S1 and S2 fibers were distinguished by the distribution of a large isoform of troponin‐T (T1; Mr = 55,000); S2 fibers in all three species contained T1 in addition to one or two smaller‐molecular‐weight variants usually associated with S1 fibers. In order to determine whether the slow fibers differed in histochemical properties, land crab claw closer muscle was cryosectioned and stained for myofibrillar ATPase and NADH diaphorase activities. Most S2 fibers had lower ATPase and higher NADH diaphorase activities than S1 fibers, which indicated that S2 fibers had a lower rate of contraction and were more fatigue‐resistant than S1 fibers. It is proposed that the S1 and S2 fibers defined by biochemical and histochemical criteria are identical to the slow‐twitch and tonic fibers, respectively, characterized physiologically.
Improved growth and development of presomite mouse embryos in whole embryo culture
Authors: Hunter E. S. , Balkan W. , Sadler T. W. 
Published: June 2005

AbstractA rotator whole embryo culture system was used to assess the growth and development of late‐primitive‐streak‐stage (Theiler stage 9‐10) mouse embryos to the limb‐bud stage of organogenesis in a variety of media containing combinations of mouse serum (MS), rat serum (RS), and Tyrode's buffer (TB). The results demonstrate that embryonic growth and morphogenesis to the early limb‐bud stage (20 somite pairs; 48‐h total culture period) mimicked that in vivo when embryos were grown for 24 h in combinations of MS:RS:TB 1:2:1 or 2:1:1 (v/v/v) and then were transferred to fresh medium containing RS:TB 3:1 at the early somite stage. When the culture period was extended for an additional 24 h (total 72‐h culture period) embryonic growth retardation was observed. Regardless of the medium employed, superior growth was observed in embryos transferred at the early somite stage when compared to embryos cultured continuously in the same medium for the entire 48‐ or 72‐h culture period.
On the diversity of sperm basic proteins in the vertebrates: VI. Cytochemical and biochemical analysis in birds
Authors: Chiva M. , Kasinsky H. E. , Mann M. , Subirana J. A. 
Published: June 2005

AbstractBy cytochemical criteria, the sperm basic proteins in birds are remarkably constant. Type 1 protamines are found in five species of birds representing four orders: Coturnix japonica (quail) and Gallus domesticus (rooster), order Galliformes; Anas platyrhynchos (duck), order Anseri‐formes; Melopsittacus undulatus (budgerigar), order Psittaciformes; Molothrus ater (cowbird), order Passeriformes. This constancy is confirmed by the isolation of electrophoretically typical protamines from sperm nuclei of quail, duck and budgerigar as well as from Carduelis carduelis (goldfinch), another passeriform bird, and Columba livia (pigeon), order Columbiformes. In each species only typical protamines are found in ripe spermatozoa; no histones are present. In quail and pigeon, several protamines of similar molecular weight can be found, whereas in duck, goldfinch, and budgerigar a single protamine component is apparent. An additional basic protein is found in budgerigar, which does not appear to be part of the ripe sperm nucleus. Such additional basic proteins have not been detected in the other species studied. No significant amounts of intermediate proteins that could be involved in spermatid maturation have been detected either cytochemically or biochemically in any of the species studied. The overall similarity amongst protamines from seven birds representing five orders might be related to the uniform mode of reproduction within the class Aves, consisting of internal fertilization and egg laying.
Induction of spawning and oocyte maturation by 5‐hydroxytryptamine in the surf clam
Authors: Hirai Setsuro , Kishimoto Takeo , Kadam A. L. , Kanatani Haruo , Koide S. S. 
Published: June 2005

AbstractGamete shedding can be induced in male and female surf clams (Spisula solidissima and sachalinensis) by injecting 5‐hydroxytryptamine (5‐HT) into the gonads. The administration of 0.4 ml of 2.0 mM 5‐HT induced spawning in all the clams tested. Shedding of gametes occurred within 2 to 3 min after the treatment and continued for about 40 min. The majority of the shed oocytes retained their germinal vesicles and underwent maturation upon insemination. The fertilized oocytes developed normally to the trocophora stage. The motility of the shed sperm was normal. 5‐HT added to the suspending medium to the final concentrations of 10 to 100, μM induced maturation of isolated Spisula oocytes in vitro. The oocytes underwent germinal vesicle breakdown, chromosomal condensation, extrusion of the first and second polar bodies, and pronuclei formation. The neurotrans‐mitter‐induced production of maturation‐promoting factor. In conclusion, 5‐HT induces gamete spawning and initiates oocyte maturation in the surf clam.
Chromatin topology during the transformation of the mouse sperm nucleus into pronucleus in vivo
Authors: Garagna Silvia , Redi Carlo Alberto 
Published: June 2005

AbstractTime relationships of sperm chromatin dispersion and sperm nucleoprotein replacement have been studied in vivo, by an in situ cytochemical approach. We used the Peulgen reaction to reveal DNA, which allows us to record both processes simultaneously, on the basis of the return after fertilization to haploid Feulgen values after sperm nucleoprotein replacement with somatic histones. We have shown that sperm nucleoprotein replacement occurs at around anaphase II, whereas sperm chromatin dispersion is massive between the anaphase and telophase II oocyte phases. The morphological pattern of sperm chromatin dispersion supports the idea that the process involves the whole sperm chromatin mass simultaneously, with the region located between the implantation fossa and the postacrosomial region the last to swell.
Effects of cytochalasins B and D on the fertilization of zebrafish (Brachydanio) eggs
Authors: Wolenski Joseph S. , Hart Nathan H. 
Published: June 2005

AbstractThe effects of selected concentrations of cytochalasins B (1–10 μg/ml; CB) and D (10, 50 μg/ml; CD) on the morphology and fertilization of zebra danio (Brachydanio) eggs were studied primarily with light and scanning electron microscopy. Eggs pretreated with either CB (10 μg/ml) or CD (10, 50 μg/ml) prepared in Fish Ringer's solution‐0.5% DMSO showed a flattened shape, alterations in the form of surface microplicae and microvilli, and occasional spontaneous exocytosis of cortical granules. All eggs preincubated in either CB or CD were activated upon transfer to tap water, showing cortical granule exocytosis, elevation of the chorion, and formation of a fertilization cone. When eggs were pretreated for 5 minutes with 1–5 μg/ml CB or 10 μg/ml CD and inseminated, they incorporated the fertilizing sperm and typically developed to the two‐cell stage. A single sperm cell attached to and fused with the sperm entry site microvilli but failed to enter the cytoplasm in eggs preincubated with 10 μg/ml CB. Eggs that were immersed continuously in either CB (10 μg/ml) or CD (50 μg/ml) 15 seconds after insemination also failed to incorporate the fertilizing sperm. Treatment of eggs after insemination with CD (10 μg/ml), however, did not prevent sperm cell incorporation or fertilization cone formation. Our drug data suggest the presence of actin‐containing filaments in the danio egg before and following fertilization. These filaments appear to play a role in maintaining the shape of the egg cell and its surface specializations and in the incorporation of the fertilizing sperm. The fertilization cone appears to form independently of actin polymerization.