bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphological and distributional changes in the eosinophilic granule cell (EGC) population of the rainbow trout (Oncorhynchus mykiss walbaum) intestine following systemic administration of capsaicin and substance P
Authors: Powell Mark D. , Wright Glenda M. , Burka John F. 
Published: June 2005

AbstractIntestinal eosinophilic granule cells (EGCs) of the rainbow trout (Oncorhynchus mykiss) have been likened to mammalian mast cells and degranulate in response to stimulation by capsaicin and substance P. This investigation was conducted to examine the effects of capsaicin and substance P on the trout intestinal EGC population and to quantify the different morphologies following systemic administration. Rainbow trout were injected intraperitoneally with capsaicin, substance P, serotonin, or vehicle controls (0.5 ug/g body weight). Fish were killed at timed intervals and the mid intestine was processed for light and electron microscopy. The number of EGCs which could be observed in the stratum compactum was quantified for each treatment over the time course of the experiment. EGCs could be classified ultrastructurally into 1 of 5 categories based on their granule morphology. The cell frequencies and relative proportion of each cell class were analyzed statistically. The frequency of EGCs in the stratum compactum of fish injected with capsaicin or substance P significantly decreased post‐injection (P < 0.05) compared to controls (saline‐ and BSA‐injected fish). Serotonin had no effect on EGC frequency, morphology, or distribution as compared with saline. Stimulation with capsaicin and substance P resulted in time‐dependent changes in both EGC granule morphology and distribution within the intestinal mucosa. Following an apparent migration of EGCs to the lamina propria and degranulation, small granuled EGC‐like cells appeared first in the lamina propria and then later in the stratum compactum. The significance of the stratum compactum as a depot for intestinal EGCs and the site for EGC maturation is discussed. © 1993 Wiley‐Liss, Inc.
Ectoderm promotes differentiation of the presumptive ventral mesoderm in early gastrulae of Bufo arenarum
Authors: Casal Fernando H. Campos , Manes Mario E. 
Published: June 2005

AbstractCultures of both isolated and conjugated explants from early gastrulae of Bufo arenarum were prepared for a study of the development of ventral mesoderm. Only combinations including components of the deep ventral marginal zone and the animal pole successfully differentiated into blood cells (erythrocytes). Histological studies indicated that, while prospective mesodermal cells constituted the only source of such cells, prospective ectodermal cells provided the necessary stimulus for this kind of differentiation. Differentiated cultures, in which the tracer of cell‐lineage fluorescein dextran amine was used to label these components, confirmed the above conclusions. These findings are discussed in the context of current concepts about the formation of mesoderm. © 1993 Wiley‐Liss, Inc.
Specificity of binding of zona pellucida glycoproteins to sperm proacrosin and related proteins
Authors: Williams R. M. , Jones R. 
Published: June 2005

AbstractA major regulatory site for species specificity of fertilization in mammals lies at the level of sperm binding to the zona pellucida. This implies a high degree of complementarity between gamete receptor molecules. One putative receptor molecule on spermatozoa is proacrosin/ acrosin which binds to zona pellucida glycoproteins (ZPGPs) non‐enzymically and with high affinity. The mechanism of recognition involves polysulphate groups in a particular stereochemical orientation and it has been suggested that this may contribute to species specificity of sperm‐egg binding. In the present work this hypothesis has been tested by challenging 125I‐labelled ZPGPs from pig, cow, and hamster eggs to recognize heterologous sperm proacrosins as well as a variety of sequencerelated and unrelated proteins. Results show that pig and cow 125I‐ZPGPs bind readily to boar, ram, and bull proacrosin but do not recognize guinea‐pig proacrosin or any of the polysulphate binding proteins from rat, hamster, or mouse spermatozoa. Hamster 125I‐ZPGPs also recognise boar, ram, and bull proacrosin as well as a range of unidentified proteins in pH3 extracts of hamster, rat, and mouse spermatozoa. The binding of ZPGPs to a variety of proteins not related to proacrosin is strongest to those with a high content of basic residues (i.e., pI > 8.5), although the secondary folding of the target protein is of major importance as boar proacrosin (pI 6.75) has the highest binding capacity of all proteins tested. Cross‐reaction of ZPGP probes was not observed to guinea‐pig proacrosin, suggesting that in this species the conformation of the protein is different to other sperm proacrosins. These results suggest that there are significant differences in the affinity of ZPGP‐proacrosin and ZPGP‐protein interactions to contribute to species specificity of sperm‐egg binding. © 1993 Wiley‐Liss, Inc.
Dopamine reduces intensity of serotonin‐induced spawning in the zebra mussel Dreissena polymorpha (Pallas)
Authors: Fong Peter P. , Noordhuis Ruurd , Ram Jeffrey L. 
Published: June 2005

AbstractThe effect of dopamine (DA) on serotonin (5‐HT)‐induced spawning in the zebra mussel Dreissena polymorpha (Pallas) was tested. Administration of 1 mM DA with either 0.3 mM or 0.5 mM 5‐HT significantly delayed spawning and reduced its intensity in both males and females compared with 5‐HT controls. In dose‐response experiments, a minimal DA concentration of 0.3 mM was necessary to delay spawning and reduce male spawning intensity to levels below that of the 5‐HT control. Mussels treated with 5‐HT‐DA or DA alone opened their valves initially, but after 1 hour most valves were closed and both inhalent and exhalent siphons appeared extended, squeezed, and narrow, with reduced aperture openings. Possible mechanisms for the observed reduction in spawning intensity are discussed. © 1993 Wiley‐Liss, Inc.
Steroid metabolism in the cortex and the medulla of the early fetal bovine ovary
Authors: Juárez‐Oropeza M. A. , Álvarez‐Fernández G. , López V. , Kawa S. , Pedernera E. 
Published: June 2005

AbstractSuspensions of cells obtained from the cortex and the medulla of the ovary of early bovine fetuses of 4–10 cm in crown‐rump (C‐R) length were used for studies of the metabolism of radiolabeled exogenous steroid precursors. Tritiated dehydroepiandrosterone, androstenedione, and testosterone were employed as precursors and their metabolic products were evaluated after separation by thin‐layer chromatography. The extent of conversion of tritiated dehydroepiandrosterone to androstenedione was higher in cells from medulla than in those from the cortex. Androstenedione was metabolized mainly to estrone, and the percent of transformation was similar in the cortex and the medulla, but the rate of formation of 17β‐estradiol was higher in the medulla than in the cortex. Furthermore, cells obtained from the cortex and the medulla aromatized testosterone to 17β‐estradiol at a similar rate. In all cases, the percent of transformation was higher in ovaries from fetuses of 4.0 cm in C‐R length than those from fetuses of 9.0–10.0 cm in C‐R length. These data suggest that, in the bovine fetal ovary, the activity of 3β‐hydroxysteroid dehydrogenase/isomerase and 17β‐hydroxysteroid dehydrogenase predominates in the medulla, whereas aromatase activity is similar in the cortex and the medulla of the early fetal bovine ovary. © 1993 Wiley‐Liss, Inc.
Regulation of prostaglandin E and F production in the goldfish testis
Authors: Wade Michael G. , Kraak Glen Van Der 
Published: June 2005

AbstractThe present studies have investigated the putative role of activators of different signal transduction pathways in the regulation of prostaglandin (PG) production by goldfish testis pieces in vitro. The protein kinase C activator (PKC) phorbol 12‐myristate 13‐acetate (PMA: 1.56‐400 nM) and calcium ionophore A23187 (62.5‐4000 nM) stimulated PGE and F production in a dose and time‐dependent fashion. There was no synergism between A23187 and PMA in stimulating PG production. PGE levels were at least 4.5 times higher than PGF levels. The phorbol ester 4α phorbol didecanoate (400 nM), which does not activate PKC, had no effect on PGE production. The synthetic diacylglycerol 1‐oleoyl‐2‐acetyl‐sn‐glycerol (100 μM), but not 1,2‐dioctanoyl‐sn‐glycerol (100 μ), stimulated PGE production. Although the gonadotropin analog human chorionic gonadotropin (1 IU/ml), adenylate cyclase activator forskolin (2 μM) and testosterone (5 ng/ml) had no effect, the cyclic nucleotide phosphodiesterase inhibitor 3‐isobutyl‐1‐methylxanthine (1 mM) and cyclic adenosine‐3′,5′‐monophosphate analog dibutyryladenosine‐3′,5′‐monophosphate (2 mM) inhibited PMA (400 nM) and A23187 (1 μM)‐stimulated PGE production. PMA and A23187 (400 nM and 1 μM, respectively)‐stimulated PGE production was inhibited by phospholipase A2 inhibitors 4‐bromophenacyl bromide, quinacrine and chloroquine (all 6.25‐400 μM) and by diacylglycerol lipase inhibitor RHC 80267 (10–100 μM), suggesting that both lipases are involved in the release of precursor fatty acids for PG synthesis by goldfish testis tissue. These data, in conjunction with earlier studies showing that PGE stimulates testosterone production by goldfish testis pieces, lend support to the contention that locally produced PGs of the E series modulate testicular steroidogenesis in teleosts. © 1993 Wiley‐Liss, Inc.
Gastrulation and mesoderm morphogenesis in the white sturgeon
Authors: Bolker J. A. 
Published: June 2005

AbstractThis study presents a detailed description of gastrulation in the white sturgeon, Acipenser transmontanus, using scanning electron microscopy, histology, and time‐lapse filming and video microscopy. This morphological analysis describes the similarity of gastrula structure in the sturgeon and the amphibian Xenopus laevis, and suggests that the species share many developmental mechanisms. It also identifies important differences, such as the equatorial dorsal lip in sturgeon, and provides a basis for interpreting experiments that test the effect of these differences on gastrulation. The onset of gastrulation in the sturgeon is marked by the appearance of a blastoporal equatorial pigment line that forms as the apices of bottle cells contract and concentrate surface pigment granules. Bottle cell formation at the blastopore lip and involution of surface material through the blastopore are strikingly similar to the equivalent processes in amphibian embryos. As gastrulation continues, a distinct cleft of Brachet forms between pre‐involution and post‐involution material. Following involution, the prospective axial mesoderm located on the dorsal surface of the late blastula (Ballard and Ginsburg: J. Exp. Zool., 213:69–103, 1980) ingresses from a central zone in the posterior archenteron roof surface in a process that is unlike any in Xenopus, but resembles events in other amphibians (Purcell, 1992; Smith: Dev. Biol., 98:250–254, 1983; King: Biol. Bull., 4:287–300, 1903). The detailed comparison of similarities and differences in gastrulation in different vertebrate lineages yields insights into the function and versatility of common developmental mechanisms. © 1993 Wiley‐Liss, Inc.
The mechanism of gastrulation in the white sturgeon
Authors: Bolker J. A. 
Published: June 2005

AbstractGastrulation in the white sturgeon, Acipenser transmontanus, involves many of the same processes as in the amphibian Xenopus laevis, but the timing and relative importance of these processes are altered so that they function appropriately in a different type of egg. In both species, convergence and extension result from a combination of radial and mediolateral cell intercalation. In sturgeons, where the blastopore lip forms at the equator, an early phase of thinning and extension of the animal cap moves the marginal zone below the equator during late blastula and early gastrula stages. This early extension without convergence is followed by convergent extension of the dorsal marginal zone after its displacement vegetally. When the animal cap is removed before gastrulation, precluding the initial extension that moves the marginal zone below the equator, autonomous convergence of the lower marginal zone produces an equatorially constricted embryo. Dorsal explants of sturgeon embryos undergo convergent extension similar to that documented in Xenopus (Keller and Danilchik: Development, 103:193–209, 1988), with distinct zones of extension in the involuting and non‐involuting marginal zone regions. The extension of cultured explants demonstrates that this morphogenetic behavior is intrinsic to the dorsal tissue. These results show that normal gastrulation depends not only on the function of these independent morphogenetic mechanisms, but also on their mechanical context in the embryo. Experimental analyses and comparison of gastrulation in similar embryos, such as those of Xenopus and sturgeons, reveal both common developmental mechanisms, and variation in their roles. © 1993 Wiley‐Liss, Inc.
Effect of follicle cells and steroidogenesis on maturation and fertilization in vitro of pig oocytes
Authors: Nagai T. , Ding J. , Moor R. M. 
Published: June 2005

AbstractFollicle cell numbers, steroidogenesis, and culture conditions were manipulated in a series of experiments designed to identify their effect during in vitro maturation of pig oocytes upon meiotic cycle progression, sperm penetration and male pronuclear formation. In Experiment 1 a static culture system was used to determine the effect of follicle cell numbers on maturation. When the follicle cell number was 3.5 × 103 cells per complex or less, cell cycle progression to metaphase II (M‐II) and male pronuclear formation were both low (<30%). Increasing follicle cell numbers to 15 × 103 per complex significantly enhanced both meiotic maturation (93%) and male pronuclear formation (83%). A further 10‐fold increase in follicle cell numbers (150 × 103), however, reduced subsequent male pronuclear formation (33%).The purpose of Experiment 2 was to determine whether the observed follicle cell effects were influenced by the type of culture system used for oocyte maturation. Comparisons were made between both static and non‐static forms of culture. Meiotic progression was significantly depressed when non‐static culture systems were used for the maturation of oocyte‐cumulus complexes containing low numbers of somatic cells (<15 × 103 cells). However, the addition of somatic cells (follicle shells) to non‐static, but not static, culture systems significantly enhanced male pronuclear formation in all groups irrespective of the number of cumulus cells in the oocyte complex.Experiment 3 investigated the effects of the steroid environment on maturation and male pronuclear formation. The addition of high levels of progesterone (1 mg/ml) from the beginning of maturation was detrimental for maturation. More interestingly, inhibition of steroidogenesis using an inhibitor of 20α‐cholesterol oxidase was without effect on meiotic progression or sperm penetration but reduced male pronuclear formation. The combined results demonstrate the importance of appropriate somatic support of oocytes as measured by their subsequent capacity to induce normal pronuclear formation after fertilization. Furthermore, studies on the required hormonal environment support published data showing that progesterone is required during maturation for subsequent male pronuclear formation. © 1993 Wiley‐Liss, Inc.
Interactions of temperature and steroids on larval growth, development, and metamorphosis in a toad (Bufo boreas)
Authors: Hayes Tyrone , Chan Ruth , Licht Paul 
Published: June 2005

AbstractThe effects of temperature and steroids [testosterone (T), estradiol (E2), and cortico‐sterone (B)] on premetamorphic growth and development were investigated in the toad (Bufo boreas). The effects of steroids were both temperature and age dependent. In the first experiment, steroids (1.1–1.4 μM) were administered by dissolving them in the water beginning 1 day after hatching at 22°C or 27°C. At 22°C, B inhibited growth (P < 0.001) but had no significant effect on development. Forelegs never emerged in B‐treated animals and all died before complete tail resorption. Discontinuation of B treatment allowed normal growth and metamorphosis, but the resulting post‐metamorphic animals were significantly shorter (snout‐vent length, P < 0.001) than after other treatments. At 22°C, T and E2 had no effect on larval growth and development or size at metamorphosis (P > 0.05), but T induced early foreleg emergence (FLE) (P < 0.005). At 27°C, B was fatal after 2 weeks of treatment, and T and E2 inhibited growth (P < 0.001) and development (P < 0.001), but did not affect time to FLE.In a second experiment at 27°C, treatment with 1.1 μM B starting 15 days after hatching induced early metamorphic events (P < 0.001), such as tail resorption and emergence of the left foreleg (but not the right), but jaw and head restructuring failed to occur. All B‐treated animals died before complete tail resorption. © 1993 Wiley‐Liss, Inc.In a third experiment, 0.275 and 1.11 μM B, starting at day 43 (stage 43), induced early FLE (P < 0.05) and decreased snout‐vent length at tail resorption (P < 0.005) without a dose effect. A higher dose of B (4.44 μM) decreased snout‐vent length at tail resorption and time to FLE (P < 0.05) but did not affect body weight at metamorphosis (P > 0.05). Animals in this experiment survived to complete tail resorption and transformed normally. The actions of B in these experiments closely resemble those observed with administration of thyroid hormones, suggesting that steroids may interact with endogenous thyroid hormones.
Targeted single‐cell induction of gene products in Caenorhabditis elegans: A new tool for developmental studies
Authors: Stringham Eve G. , Candido E. Peter M. 
Published: June 2005

AbstractHeat shock promoters have been employed to achieve tightly regulated expression of transformed genes in a wide variety of model systems including tissue culture cells, bacteria, yeast, Drosophila, and more recently Caenorhabditis elegans. Here we investigate the feasibility of using a laser microbeam to induce a sub‐lethal heat shock response in individual cells of C. elegans. We demonstrate that in transgenic strains carrying heat shock promoter‐lacZ fusions, single cell expression of β‐galactosidase in a variety of cell types of endodermal, mesodermal, or ectodermal origin can be achieved after pulsing with a laser. A tissue‐general, inducible promoter can therefore be converted into one of single cell specificity which can be induced rapidly at any point in development, offering unique opportunities to study cell‐cell interactions in C. elegans. This technique defines a new approach to generate mosaic animals and may be adaptable to other organisms or tissues. © 1993 Wiley‐Liss, Inc.
Responses of isolated vela of nudibranch larvae to inducers of metamorphosis
Authors: Pires Anthony , Hadfield Michael G. 
Published: June 2005

AbstractLarvae of the aeolid nudibranch Phestilla sibogae metamorphose in response to a water‐soluble factor derived from their adult prey, the coral Porites compressa. Destruction of the velum, a ciliated larval swimming and feeding organ, is one of the major morphogenic events that occurs during metamorphosis. Previous work established that whole larvae metamorphose in response to the natural coral‐derived inducer (CI) and to choline, and shed the velum without completing metamorphosis in response to hydrogen peroxide (H2O2). In the present study, excised velar lobes were maintained in vitro while their responses to known inducers of metamorphosis were examined. In this way direct tissue‐level morphogenic effects of inducers could be discerned. Isolated velar lobes were unaffected by CI and by choline (5 mM). “Donor” larvae (each of which had supplied a single velar lobe used in these experiments) and unoperated controls lost their vela in response to both treatments. These results are consistent with the hypothesis that morphogenic effects of CI are mediated by the central nervous system. H2O2 (0.2 mM) caused disintegration of isolated velar lobes, and caused nearly all donor and unoperated larvae to shed their vela. © 1993 Wiley‐Liss, Inc.
Two GnRHs fluctuate in correlation with androgen levels in the male frog Rana esculenta
Authors: Fasano Silvia , Goos Henk J. Th. , Janssen Coby , Pierantoni Riccardo 
Published: June 2005

AbstractChickenII‐(cII‐) and salmon (s‐) GnRH levels have been measured in the male frog Rana esculenta during the annual cycle. The presence of pituitary binding activity for both peptides and plasma androgen levels has been investigated in order to give insight into the significance of the dual control exerted by the GnRH forms present in the R. esculenta brain. ChickenII‐ and s‐GnRHs showed high values during the spring‐summer period. Conversely, while cII‐GnRH peaked in February, s‐GnRH declined slowly from February until May. Plasma androgen levels increased as the peptides decreased during the autumn‐winter period. Still high androgen levels (but significantly lower as compared with winter concentrations) were found during spring. Using iodinated cII‐GnRH, GnRH binding sites were detected in pituitary preparations when the corresponding peptide concentration decreased in the brain. On the contrary, no binding sites were found using labeled s‐GnRH. Our results indicate that cII‐GnRH has a hypophysiotropic activity, while the role of s‐GnRH needs to be further investigated. © 1993 Wiley‐Liss, Inc.
Detection of insulin receptors in newt liver and forelimb regenerates and the effects of local insulin deprivation on epimorphic regeneration
Authors: Foty Ramsey A. , Liversage Richard A. 
Published: June 2005

AbstractPrevious in vivo and in vitro studies indicate that insulin is required in adult newt forelimb regeneration. The objectives of the current study were 1) to detect insulin receptors in the liver (a classical target organ for insulin) and once verified, detection of insulin receptors in the adult newt forelimb regenerate; and 2) to determine whether locally implanting insulin antibody‐soaked hydrolyzed polyacrylamide beads (hypa beads) into a regenerating forelimb blastema would affect its growth and/or differentiation. The results show that insulin receptors are detectable in the plasma membranes of newt liver and forelimb regenerates. Radioiodinated bovine insulin binding is time‐dependent and specific; unlabeled bovine insulin competes with labeled insulin for binding to NLPM more effectively than does insulin‐like growth factor‐I, guinea pig insulin, and glucagon. The newt hepatic insulin receptor binds insulin with high affinity (1.1 nM−1) and low capacity (63 ± 8 fmoles/mg). The size of the alpha subunit of the newt insulin receptor is 130 kDA and that of the beta subunit is 95 kDa. The β subunits undergo insulin‐stimulated phosphorylation in response to insulin. An autoantibody against the human insulin receptor recognizes the newt receptor protein. Insulin receptors are also detectable in 15 and 20 day newt forelimb regenerates. Specific immunogold labelling of the receptor‐bound antibody appears to be restricted to the cellular processes of the regenerate. Implanting hypa beads soaked with purified insulin antibody into regenerating adult newt forelimbs results in abnormal growth and differentiation of the regenerates, confirming that insulin plays an essential role in adult newt forelimb regeneration. © 1993 Wiley‐Liss, Inc.