bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vitellogenin in the surface mucus of tilapia (Oreochromis mossambicus): Possibility for uptake by the free‐swimming embryos
Authors: Kishida Mitsuyo , Specker Jennifer L. 
Published: June 2005

AbstractTilapia (Oreochromis mossambicus) produce two forms of vitellogenin, designated tVTG‐200 and tVTG‐130 to indicate the molecular masses (kDa) of their monomeric forms. The female of this species broods the embryos in her mouth, and they nip at her sides. Enzyme‐linked immunosorbent assays (ELISAs) and Western blots using the antisera to tVTG‐200 and tVTG‐130 were used in this study to show the presence of tVTGs in the surface mucus of vitellogenic females and estradiol (E2)‐treated male tilapia. Gut extracts from the free‐swimming embryos exhibited a displacement curve in ELISAs for tVTG‐200 and tVTG‐130. Western blot analyses of the esophagus/ stomach extract of the embryo showed no intact tVTGs, although proteins at 20.8 and 18.1 kDa were detected by the antiserum to tVTG‐200 and a protein at 106 kDa by the antiserum to tVTG‐130, which were similar to the proteins found in the extract of the yolk sac. Immunocytochemistry for tVTG‐200 and tVTG‐130 demonstrated positive cross‐reaction in the gut content of the embryo. However, gut extracts from embryos which were separated from the mother showed cross‐reactivity in ELISAs similar to those taken from the embryos hatched in the mouth of the mother. The availability of VTGs in the mucus of the mother raises the possibility of continued nutrient supply from the mother for post‐hatched embryonic tilapia. Alternative sources of the yolk protein‐like substances inside the gut of the embryos are considered. © 1994 Wiley‐Liss, Inc.
Acid‐base status of a pulmonate land snail (Helix aspersa) and a prosobranch amphibious snail (Pomacea bridgesi) during dormancy
Authors: Scholnick David A. , Snyder Gregory K. , Spell Angel R. 
Published: June 2005

AbstractChanges in metabolism and acid‐base status were compared during dormancy in the pulmonate land snail Helix aspersa and a prosobranch amphibious snail Pomacea bridgesi. The typical condition of higher blood PCO2 and bicarbonate levels for air‐breathing versus water‐breathing vertebrates was shown for the two snail species. When exposed to dry air for 24 hr, both species depressed oxygen uptake by about 65%. In Pomacea, hypercapnia (increase in hemolymph PCO2 from 5.5 to 18 torr) resulting from dormancy produced no significant change in pH due to large increases in bicarbonate (over 17 mmol/l). In Helix, on the other hand, hypercapnia (increase in hemolymph PCO2 from 13 to 18 torr) resulting from dormancy produced a significant decrease in pH and a less than 7 mmol/l increase in bicarbonate. Pre‐existing high levels of bicarbonate in Helix may prevent compensation of hypercapnia resulting from dormancy, similar to the case described for air‐breathing vertebrates. Complete compensation of respiratory acidosis during the first 24 hr of dormancy in Pomacea suggests that metabolic rate suppression is independent of pH. © 1994 Wiley‐Liss, Inc.
Weak applied voltages interfere with amphibian morphogenesis and pattern
Authors: Metcalf M. E. Mourey , Borgens Richard B. 
Published: June 2005

AbstractWe have imposed steady DC electric fields over developing gastrula and neurula stage axolotls,Ambystoma mexicanum. These applied voltages were meant to confound cues provided by endogenous currents and fields that we have measured and believe to be controls of pattern and morphogenesis during early development. Applied voltages in the physiological range (25–75 mV/mm) cause severe disruption of development when imposed over neurulae whose orientation within the field is random or fixed. In the latter case, developmental defects are more likely to occur at that end of the neurula (rostral or caudal) that faces the cathode, or negative pole, of the applied field. In neurulae whose orientation within the field was fixed, the lowest magnitude producing developmental abnormality was between 5 and 25 mV/mm. Physiological measurement of the embryonic transepithelial potential (TEP) when perturbed by artificially applied voltages demonstrates that ectoderm facing the cathode is hyperpolarized, while ectoderm facing the anode is depolarized at all fields strengths tested. These data show that the electrical polarity of embryonic ectoderm is predictably disrupted by applied voltages. Though applied voltages exert this same effect on the ectoderm of gastrulae, exposure only during gastrulation does not lead to developmental abnormality. This observation demonstrates that the applied electric field does not harm the embryo in some non‐specific way and further emphasizes the stages of neurulation as those most sensitive to artificially applied or endogenous voltages. These data strongly support the notion the polarized natural voltages within amphibian embryos are controls of their emerging pattern. © 1994 Wiley‐Liss, Inc.
Gender specific developmental transformation of a cockroach bifunctional muscle
Authors: Stokes Darrell R. , Malamud Jean G. , Schreihofer Derek A. 
Published: June 2005

AbstractAdult male and female cockroaches,Periplaneta americana, differ in their capacity for sustained flight. Tethered 20 day adult males flap their wings about 15 min; females 12 seconds. Males are less massive and have greater total wing area than do females, with wing loading only about half that of the female. The basalar muscle, a major wing depressor in flight, is also sexually dimorphic. In males it is 1.5× more massive and has a cross sectional area 1.2× greater than the female homologue. Muscle fibers of the adult male and female basalar muscles are ultrastructurally and biochemically distinct. Female fibers have a myofilament array similar to that of other non‐flight locomotory muscles, with 10–12 actin filaments surrounding each myosin filament. Adult male fibers typically have six actin filaments around each myosin filament. The male fibers also appear to be more oxidative. The volume density of mitochondria is about 3× greater and the specific activity for citrate synthase, an oxidative indicator, is 3.5× greater in male fibers than in female fibers. Male basalar muscle shows an enhanced ability to resist fatigue when its motoneurone is stimulated at flight frequency; homologues from the male terminal nymph and 20 day adult female are both highly fatiguable. The basalar muscle of both male and female terminal nymphs are similar in ultrastructural and biochemical profile and are not greatly different from the adult female. In male roaches there may be important neuronal or hormonal inputs at about the time of the terminal molt to adulthood that direct the transformation of the basalar muscle in time for the assumption of a new behavioral role—flight. © 1994 Wiley‐Liss, Inc.
Toxic effects of b̃‐aminopropionitrile treatment on developing chicken skin
Authors: Marsh Randall G. , Gallin Warren J. 
Published: June 2005

Abstractβ‐aminopropionitrile (BAPN), a compound that inhibits crosslinking of collagen, has been widely used to examine the function of collagen in developing tissues. We used BAPN to examine the function of collagen during the formation and patterning of feather rudiments in embryonic chicken skin. Organ cultures of skin were treated with different concentrations of BAPN and examined for changes in morphology, histology, and extent of collagen crosslinkage. Increasing concentrations of BAPN led to striped patterns of feather rudiments, increases in feather rudiment diameter, and increases in skin thickness in cultured skin. These changes in morphology were paralleled by a progressive decrease in collagen crosslinkage as the concentration of BAPN was increased. However, these changes were also paralleled by an increase in cell death in the epidermis. Culture of monolayers of separated epidermal and dermal cells in the same concentration range of BAPN that altered feather development in the organ cultures showed that BAPN killed epidermal cells but not dermal cells. Our reults suggest that developmental alterations caused by BAPN may, in some cases, be due to acute toxicity to specific cell types, and not simply to inhibition of collagen crosslinkage. © 1994 Wiley‐Liss, Inc.
Mosaic expression of an Hprt transgene integrated in a region of Y heterochromatin
Authors: Pravtcheva Dimitrina D. , Wise Thomas L. , Ensor Nancy J. , Ruddle Frank H. 
Published: June 2005

AbstractThe sensitivity of small transgenes to position effects on their expression suggests that they could serve as indicators of the chromatin properties at their integration site. In particular, they might be expected to provide information on the functional properties of mammalian heterochromatin. We have produced a transgenic line that carries a mouse Hprt minigene on the Y chromosome. In situ hybridization localized the transgene to the heterochromatic portion of the Y. Analysis of transgene expression by isoelectric focusing indicated that the transgene is expressed in a mosaic pattern, and expressing cells have different levels of transgene activity. These findings can be explained as a position effect variegation induced by Y heterochromatin. However, two other transgenes, located at autosomal sites, also showed mosaic activity. If the mosaic transgene expression is attributed to the influence of the chromatin at the insertion site, the Y heterochromatin would appear less potent than some autosomal regions at inducing variegation. An alternative explanation consistent with our results is that the mosaic expression is a semi‐autonomous characteristic of these transgene loci. Transgene‐expressing and non‐expressing cells differed in their ability to grow and be cloned in vitro, indicating that cellular differentiation affected the chromatin structure of the transgene locus on the Y. Karyotype analysis of male mice with the Y‐linked transgene and from control male mice carrying the human HPRT transgene, or the mouse Pgk‐1 gene at autosomal sites, indicated that the transgene‐carrying Y is prone to non‐disjunction, generating cells with two (or more) or no Y chromosomes in equal proportion. Further studies will determine if the propensity of this Y chromosome to mitotic errors is also observed in vivo. © 1994 Wiley‐Liss, Inc.
Rapid induction of a hyperciliated phenotype in zinc‐arrested sea urchin embryos by theophylline
Authors: Stephens R. E. 
Published: June 2005

AbstractZinc ions, present since fertilization, will arrest embryos of the sea urchin Tripneustes gratilla at the hatched blastula stage, but such embryos lack long cilia, the usual characteristic of animalized embryos. Eventually these embryos will express a minimal long cilia phenotype, with a mean population < 1.4 times that of control blastulae, but only after contemporaneous control embryos gastrulate. Theophylline will rapidly but minimally animalize embryos when added after hatching, but its inductive ability decreases as the embryos gastrulate. Theophylline‐animalized embryos produce cilia whose mean population length is > 1.5 times that of control blastulae. At any point from the time of hatching up until control embryos complete gastrulation, theophylline added to zinc‐arrested embryos will induce a hyperciliated phenotype with a mean population length nearly 3 times that of control blastulae. The elongation of cilia is immediate and significantly exceeds the rate of normal ciliary regeneration. Initially requiring the presence of theophylline, the hyperciliated phenotype becomes stable as control embryos begin gastrulation and, when deciliated, the induced embryos will regenerate hyperlong cilia in the absence of theophylline. The time dependence for both induction and phenotype stability would suggest that certain timing mechanisms are still operative in zinc‐arrested embryos. This inducible system should facilitate studies of length control during ciliary elongation and regeneration. © 1994 Wiley‐Liss, Inc.
Morphological and functional changes accompanying the acquisition of meiotic competence in ovarian goat oocyte
Authors: De Smedt Véronique , Crozet Nicole , Gall Laurence 
Published: June 2005

AbstractIn order to determine at which follicular size goat oocytes were capable of resuming and completing meiosis, we evaluated their ability to mature in vitro and measured their maturation promoting factor (MPF) activity by histone H1 kinase assay. The results indicated that goat oocyte meiotic competence developed progressively in follicles ranging from 0.5 to 3 mm, the oocytes acquired the ability to resume meiosis in follicles of 0.5–0.8 mm, to reach metaphase I (MI) in follicles of 1–1.8 mm, and to reach metaphase II (MII) in follicles larger than 3 mm. The presence of MPF activity was first observed in oocytes arrested at early prometaphase I and reached a maximum level in oocytes blocked in metaphase I (MI). In the second part of this study, RNA synthesis and nucleolar changes were analyzed during the growth period. The acquisition of meiotic competence was accompanied by nucleolar compaction and a dramatic decrease in RNA synthesis. Changes in protein patterns were also analyzed, but only slight differences were observed among oocytes from the different classes. © 1994 Wiley‐Liss, Inc.
Influence of gonad‐stimulating substance on ovarian 1‐methyladenine levels responsible for germinal vesicle breakdown and spawning in the starfish Asterina pectinifera
Authors: Mita Masatoshi , Nakamura Masaru 
Published: June 2005

AbstractIn starfish oocytes, 1‐methyladenine (1‐MeAde) induces not only germinal vesicle breakdown (GVBD) but also follicular envelope breakdown (FEBD), releasing the oocytes from the ovaries, i.e., spawning. This study was undertaken to examine changing levels of 1‐MeAde within ovaries of the starfish Asterina pectinifera after treatment with gonad‐stimulating substance (GSS). 1‐MeAde production in ovaries was markedly dependent on GSS concentration. Although the period until oocyte release from the ovaries was shortened to as little as 19 min when the GSS concentration was increased to 0.1 mg/ml, about 5 min of treatment with GSS (0.1 mg/ml) was sufficient for induction of oocyte release, involving GVBD and FEBD. Almost the same duration of treatment with 1‐MeAde at a concentration of 0.1 μM was required for spawning. Since the increase in the 1‐MeAde level was correlated with a parallel rise in ovary wet weight, the internal content of 1‐MeAde in ovaries was estimated to be 1 g wet weight ovary/ml. The content of 1‐MeAde within the ovaries was calculated to reach about 0.18 μM during 5 min of GSS treatment. It is thus concluded that the 1‐MeAde content is sufficient to induce GVBD and FEBD of oocytes in starfish ovary. © 1994 Wiley‐Liss, Inc.
Fertilization of the lamprey (Lampetra japonica) eggs: Implication of the presence of fast and permanent blocks against polyspermy
Authors: Kobayashi Wataru , Yamamoto Tadashi S. 
Published: June 2005

AbstractWe have carried out a morphological examination to analyze the mechanism of monospermic fertilization in the lamprey, Lampetra japonica. Upon insemination, many sperm passed through a “tuft” of jelly that is found only on the animal pole area of the egg and underwent the acrosome reaction after they came into contact with the outer surface of the two‐layered vitelline envelope. The acrosomal filaments were admitted into the envelope and their tips touched the ooplasmic surface. The Hoechst dye transfer method revealed that a single sperm showed intense fluorescence before its nucleus penetrated the vitelline envelope; this indicated the actual fusion of the gametes. No other sperm with acrosomal filaments fluoresced, however. These findings indicate that a fast block against polyspermy is established at the plasma membrane level and prevents additional sperm‐egg fusion.The separation of the ooplasmic surface from the vitelline envelope (perivitelline space formation) was initiated beneath the margin of the animal pole region and progressed toward the animal and vegetal poles of the egg. At this stage, the head of a fertilizing sperm passed through the thickness of the vitelline envelope. The nuclei of supernumerary sperm were unable to enter the inner layer of the vitelline envelope. During the early phase of the perivitelline space formation at the animal pole region, many thin threads and one, or a small number, of the thick projection(s) of the ooplasm connected the envelope with the vitellus. A fertilizing sperm invariably moved along one of the thin threads and was embedded in the ooplasm at the animal pole region. Cytochalasin B inhibited sperm from passing through the inner layer of the vitelline envelope. When ionophore‐activated eggs were inseminated, the tips of the acrosomal filaments were prevented from touching the ooplasmic surface by the intervening presence of the perivitelline space. None of these sperm passed through the vitelline envelope. These findings suggest that the fusion of the acrosomal filament with the egg plasma membrane is a prerequisite for the passage of sperm through the inner layer of the vitelline envelope. Furthermore, actin‐mediated ooplasmic activity is probably involved in the passage. We conclude that the formation of the perivitelline space at the animal pole region contributes to the establishment of a permanent block against polyspermy in the lamprey egg. © 1994 Wiley‐Liss, Inc.
Contribution of dietary and loading changes to the effects of suspension on mouse femora
Authors: Simske S. J. , Broz J. J. , Fleet M. L. , Schmeister T. A. , Gayles E. C. , Luttges M. W. 
Published: June 2005

AbstractThe present study assessed the contributions of feeding changes and unloading to the overall measured effects of 2‐wk hindlimb (Tail) suspension on the mouse femora. Feeding changes were addressed by considering the effects of matched feeding among suspended and control mice. The effects of hind limb unloading were considered by comparing suspended mice to mice equipped identically (though not suspended) and matched‐fed. The feeding and unloading aspects of suspension appear to cause distinctly differing effects on the stereotypic modeling of the femora. Matched‐feeding was accompanied by increased resorption surface in comparison to suspended mice, while unloading led to reduced bone formation at the mid‐diaphysis of the femora. Reduced mineral content was observed in the bones of suspended mice when compared to the other mice groups, but without increased resorption surface. Thus, the unloading aspects of the antiorthostatic suspension protocol apparently causes reduced formation and mineralization in the femur. © 1994 Wiley‐Liss, Inc.
Trophic exchanges between parent and young during development of Glossiphonia complanata (Annelida, Hirudinea)
Authors: De Eguileor Magda , Daniel Sergio , Giordana Barbara , Lanzavecchia Giulio , Valvassori Roberto 
Published: June 2005

AbstractGlossiphoniids are iteroparous hirudineans that brood their offspring. The young are attached by the posterior sucker to the parent's ventral side until development is complete. The weight loss of the brooding adults is commonly attributed to their reduced possibility of feeding and to the increased metabolic expense for movements needed to ventilate the offspring. The present study showed that there is a passage of nutritive substrates between the parental body wall and the young's sucker. A possible correlation between this passage and the reabsorption of some muscle fibers that occurs in the adult's body wall is also analyzed. © 1994 Wiley‐Liss, Inc.
Estrogen and progesterone receptors in lizard Podarcis s. sicula oviduct: Seasonal distribution and hormonal dependence
Authors: Paolucci M. , Di Fiore M. M. 
Published: June 2005

AbstractBoth estradiol (ER) and progesterone (PR) receptors have been found in the oviduct of the lizard Podarcis s. sicula. Their concentrations change according to the reproductive cycle and under different hormonal treatment. The estradiol receptor binds DES with high affinity (Kd = 4.4 ± 6.9 × 10−1 M) and low capacity (7.0 ± 2.1 × 10−10 M). The progesterone receptor binds both 3H‐progesterone and 3H‐R5020 with high affinity (Kd = 1.2 ± 2.2 × 10−9 M) and low capacity (0.5 ± 2.2 × 10−10 M). PR elution profile on DNA‐cellulose shows two peaks eluting at 0.15 M NaCl and 0.27 M NaCl for the cytosol and 0.14 M NaCl and 0.26 M NaCl for the nuclear extract. When analyzed by isoelectrofocusing, PR shows two peaks at pH 7.8–8.0 and 6.8–7.0. During the reproductive cycle, the peak of occupied ER in the nuclei precedes the increase in occupied PR. This pattern suggests a sequential action of estradiol and progesterone on the oviduct. In fact, while estradiol is involved in oviduct growth in early spring, progesterone stimulates glandular activity in the mature oviduct. Long term estradiol treatment up‐regulates nuclear occupied PR, but down‐regulates it when administered in combination with progesterone. On the other hand, progesterone alone or in combination with estradiol, prevents 17β‐estradiol effects on nuclear occupied ER. © 1994 Wiley‐Liss, Inc.
Tissue‐specific expression of calbindin‐D28K gene during ontogeny of the chicken
Authors: Sechman A. , Shimada K. , Saito N. , Ieda T. , Ono T. 
Published: June 2005

AbstractThe vitamin D3‐dependent calcium binding protein, calbindin‐D28K (CaBP‐D28K), plays an important role in transepithelial calcium translocation. To evaluate its role in chick embryonic calcium metabolism, steady‐state levels of CaBP‐D28K mRNA in various tissues of the chick embryo were determined by Northern blot and slot blot analyses, and CaBP‐D28K concentrations in the examined tissues and plasma were estimated by RIA. High levels of CaBP‐D28K mRNA were found in the embryonic kidney (mesonephros) on embryonic day (E) 10 and E12 and thereafter gradually decreased until hatching. CaBP‐D28K mRNA levels were low in the yolk sac until E16 but increased on E18 and reached a maximum on E20. A steady increase in CaBP‐D28K mRNA levels was observed in the cerebellum during the development from E10 to post‐hatching. CaBP‐D28K mRNA levels in the intestine were very low during the incubation period but significantly increased on days 1 and 7 after hatching. By Northern blot analysis, CaBP‐D28K mRNA was barely detectable in liver, heart, and chorioallantoic membrane of the embryonic chick. Changes in immunoreactive CaBP‐D28K of each tissue paralleled observed changes in mRNA levels. In plasma, measurable levels of CaBP‐D28K were found as early as E8 and were stable until E18, when 6.5‐fold increase was observed compared to E16. The highest level of CaBP‐D28K in plasma was found on E20 and decreased after hatching. These temporal profiles of CaBP‐D28K suggest that it may play an important role in the regulation of chick embryonic calcium homeostasis. © 1994 Wiley‐Liss, Inc.