bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cervical kinematics during drinking in developing chickens
Authors: Heidweiller Jan , Van Der Leeuw Angelique H. J. , Zweers Dr. Gart A. 
Published: June 2005

AbstractDevelopment of head neck motion patterns is studied in drinking chickens to examine (1) general motion principles, (2) ontogenetic changes in these patterns, and (3) whether pattern changes are due to scaling effects during growth. Behavioral patterns are analyzed by high speed filming, radiography, and calculation of rotation patterns for each joint during all movement patterns.Flexibility and variability are great, but representative kinematic patterns are selected for immersion, upstroke, and tip‐up phases. Five principles were found that control cervical motion. Two principles maximize rotation efficiency: the geometric and lever arm principles. Two trajectory compensating principles occur; one controls compensation for overflexion, and the other corrects curved into straight trajectories of head motion. One principle occurs that minimizes rotation force if large forces tend to develop in one joint. This principle results in a characteristic cervical motion pattern (“bike chain” pattern).There are three developmental periods: (1) hatchlings (2) chickens 1 to 4 weeks old (1–4W), and (3) older than 4 weeks. Each period is characterized by different kinematic patterns. In 1–4W chicks, the rotation force is minimized. In older stages, the cervical joints rotate according to geometric and lever arm principles. The totally different motion pattern in hatchlings results from a different behavioral reaction to water and the influence of large centrifugal forces. Transitions in cervical motion patterns are connected to effects of scaling, primarily changes in head and body weights. Changes in motion patterns are not related to changes in anatomical characters such as flexion extremes and relative length of each vertebra since these are similar in all stages. © 1992 Wiley‐Liss, Inc.
Localization of β‐endorphin‐like immunoreactivity in the nervous system of the adult newt, Notophthalmus viridescens
Authors: Vethamany‐Globus Swani , Michener Gregory 
Published: June 2005

AbstractUsing indirect immunofluorescence methods, we have localized for the first time in the newt, Notophthalmus viridescens, β‐endorphin (β‐ep)‐like immunoreactivity in the neurons of spinal ganglia (SPG), spinal cord (SPC), as well as in the hypothalamic region of the brain. An examination of serially sectioned SPG showed that the β‐ep‐positive neurons, cell bodies, and nerve fibers were distributed at all levels of SPG. Peripheral regions of the perikarya of β‐ep‐positive SPG neurons exhibited intense staining for β‐ep, the central nuclear region remaining nonreactive. In SPC, brightly staining fibers were seen entering the afferent nociceptive input areas, namely the Lissauer's tracts, substantia gelatinosa, and the dorsal ascending columns. Dot‐fiber immunofluorescence pattern was observed throughout the gray matter of SPC representing β‐ep‐positive, secondary sensory neurons as well as interneurons. Also, discrete cluster of neurons located deep in the gray matter of SPC stained positively to β‐ep antisera. This study not only demonstrates for the first time the presence of β‐ep like material in the newt, more specifically in SPG and SPC, but also raises the question of a possible link between β‐ep and newt limb regeneration as previous work has shown that SPG support limb regeneration in a denervated‐amputated newt forelimb. © 1992 Wiley‐Liss, Inc.
Preloading of micromolar intracellular Ca2+ during capacitation of Sicyonia ingentis sperm, and the role of the pHi decrease during the acrosome reaction
Authors: Lindsay Leann L. , Clark Wallis H. 
Published: June 2005

AbstractIn studying the mechanism controlling the sperm acrosome reaction (AR) in the marine shrimp Sicyonia ingentis, intracellular Ca2+ and pH were measured using the fluorescent indicators Fura‐2 and Fluo‐3 for Ca2+, and SNARF‐1 for pH. Capacitated sperm possessed an apparent resting Ca2+ concentration of 1–2 μM which remained constant upon induction of the AR with egg water. Uncapacitated sperm had extremely low Ca2+ levels and did not respond to egg water. These results suggest that, while in other species the Ca2+ is elevated to micromolar levels during initiation of the AR, S. ingentis sperm are preloaded with Ca2+ during capacitation and the trigger for the AR is downstream of the Ca2+ increase. The notion that Ca2+ influx is not involved at the actual time of the AR in capacitated S. ingentis sperm is supported by the inability of Ca2+ ionophore A23187 to induce the AR and the ineffectiveness of Ca2+ channel antagonists to block egg water‐induced AR. Measurements of capacitated sperm pH showed a significant decrease during the first 10–15 min of the AR, which did not correlate temporally to either acrosomal exocytosis (at 5 min post‐induction) or filament formation (after 45 min). Inhibition of egg protease activity required for induction of filament formation did not inhibit the pH drop, indicating that intracellular acidification is not the final trigger for filament formation, although it may be required prior to action of the protease. © 1992 Wiley‐Liss, Inc.
Behavioral thermoregulation by hypoxic rats
Authors: Dupré R. Keith , Owen T. Lon 
Published: June 2005

AbstractTo address whether a shift in hypothalamic thermal setpoint might be a significant factor in induction of hypoxic hypothermia, behavioral thermoregulation was examined in 7 female Sprague‐Dawley rats implanted with radiotelethermometers for deep body temperature (Tb) measurement in a thermocline during normoxia (PO2 = 125 torr) and hypoxia (PO2 = 60 torr). Normoxic rats (TNox) selected a mean ambient temperature of 19.7 ± 1.4 (SE) °C and maintained Tb at 37.0 ± 0.2°C. Hypoxic rats selected a significantly higher ambient temperature (THox = 28.6 ± 2.2°C) but maintained Tb significantly lower at 35.5 ± 0.3°C. Without a thermal gradient (ambient temperature = 25°C), Tb during hypoxia was 35.4 ± 0.4°C. The maintenance of a lower body temperature during hypoxia through behavioral thermoregulation despite having warmer temperatures available supports the hypothesis that the thermoregulatory setpoint of hypoxic rats is shifted to promote thermoregulation at a lower Tb, effectively reducing oxygen demand when oxygen supply is limited. © 1992 Wiley‐Liss, Inc.
Ultimobranchial body and parathyroid glands of the freshwater snake Natrix piscator in response to vitamin D3 administration
Authors: Srivastav Ajai K. , Rani Ladli 
Published: June 2005

AbstractVitamin D3 (20 I.U./100 g body wt) was administered to the freshwater snake Natrix piscator for 15 days. Elevation of serum calcium and inorganic phosphate levels was observed after the treatment. The ultimobranchial body became active whereas the parathyroid glands exhibited reduced activity. © 1992 Wiley‐Liss, Inc.
Activation of Xenopus Laevis eggs in the absence of intracellular Ca activity by the protein phosphorylation inhibitor, 6‐dimethylaminopurine (6‐DMAP)
Authors: Zhang Shi Cui , Masui Yoshio 
Published: June 2005

AbstractXenopus laevis eggs pricked or microinjected with water or saline in medium containing a limited quantity of free Ca (1.0 to 2.0 μM) remain unactivated for at least 6 hr, even after transfer to oocyte medium containing Ca at higher concentrations (0.5–1.0 mM). These injected eggs, when later pricked in oocyte medium or exposed to A23187 or urethane are fully capable of activation. This confirms the observations of Wangh ('89). However, eggs injected in this Ca‐limited medium (CaLM) with 6‐DMAP as well as those simply exposed to this drug undergo changes characteristic of activation, including cortical contraction, cortical granule breakdown, a loss of MPF and CSF activities, and pronuclear formation. The time required for 6‐DMAP to induce egg activation is inversely correlated to its concentration. Interestingly, eggs that have been injected with EGTA, and thus are unable to respond to activation stimuli such as pricking and A23187 or urethane treatment, can also be activated by exposure to 6‐DMAP. In contrast, eggs exposed to or injected with a 6‐DMAP analogue (6‐aminopurine or puromycin) or a protein synthesis inhibitor (cycloheximide or emetine or puromycin) are not activated. As well, eggs injected in CaLM with 6‐DMAP simultaneously with a phosphatase inhibitor (NaF or ammonium molybdate) fail to become activated. Although 6‐DMAP‐activated eggs remain at the pronucleus stage so long as 6‐DMAP is present, they resume cell cycle activities after the drug is with‐drawn. They form cleavage furrows, disassemble pronuclear envelopes, and recondense chromosomes. Also, MPF activity reappears and cycles at least twice, peaking each time shortly before cleavage furrow formation. These results suggest that activation of Xenopus eggs arrested at metaphase II by inhibition of protein phosphorylation does not require intracellular Ca release and that maintenance of the egg at metaphase II depends upon continuous protein phosphorylation. © 1992 Wiley‐Liss, Inc.
Glycerol is a colligative antifreeze in some northern fishes
Authors: Raymond James A. 
Published: June 2005

AbstractMany polar marine fishes produce macromolecular antifreezes that act in a non‐colligative way to prevent freezing. In this report, a new type of freezing avoidance is described in which the rainbow smelt, Osmerus mordax dentex, in addition to producing a macromolecular antifreeze, avoids freezing by increasing the osmolality of its body fluids. In smelt living in −2.0°C water, osmolality exceeded 1.0 M, making it among the highest found in bony fishes, and the only known case of a near isosmotic condition in a marine teleost. High osmolalities, but less extreme than those shown in the rainbow smelt, were found in another smelt species and two species of greenling. The high osmolalities in each species are largely due to glycerol, an osmolyte that has not previously been reported in fishes. Glycerol appears to be produced only at subzero temperatures, and in the rainbow smelt reaches its highest concentration, 0.4 M, at environmental temperatures near the freezing point of seawater. © 1992 Wiley‐Liss, Inc.
Synthesis and secretion of low molecular weight cuticular proteins during heat shock in the tobacco hornworm, Manduca sexta
Authors: Lohmann Catherine M. Fittinghoff , Riddiford Lynn M. 
Published: June 2005

AbstractIn the tobacco hornworm, Manduca sexta, heat shock normally elicits synthesis of the classic heat‐shock proteins. A 1‐hr heat shock of 42°C and above can also increase the relative synthesis of certain 12–18 kD proteins in the epidermis. These 12–18 kD proteins were identified as cuticular proteins for several reasons. Like cuticular proteins, they appear only in the epidermis. They can be precipitated from epidermal homogenates with an antiserum to larval cuticle. The same conditions that increased labeled 12–18 kD proteins in the epidermis also increased labeled 12–18 kD proteins in the cuticle. Some of the epidermal increase may result from a partial inhibition of secretion to the cuticle during 46°C heat shock, causing abnormal accumulation in the epidermis. However, slight increases also occur at lower temperatures, which do not inhibit secretion detectably. Preliminary results also indicate that total quantities of at least one cuticular protein mRNA may increase during heat shock, either because of increased transcription or increased mRNA stability. © 1992 Wiley‐Liss, Inc.
Physiological cost of pregnancy in a viviparous lizard (Sceloporus jarrovi)
Authors: Demarco Vincent , Guillette Louis J. 
Published: June 2005

AbstractThe V̇o2 (standard metabolic rate; cc · h−1) of pregnant Sceloporus jarrovi increases to a maximum near term. Immediately following parturition, V̇o2 decreases sharply. Approximately 93.6% of the V̇o2 of late pregnant S. jarrovi is due to litter and non‐reproductive female V̇o2. The difference between measures of the V̇o2 of late pregnant lizards and late pregnant V̇o2 estimated by summing litter and nonreproductive V̇o2 (6.4%) represents the physiological cost of maintaining a litter. This estimate of the physiological cost of pregnancy in S. jarrovi is similar to that reported for mammals; however, it is lower than other estimates of the cost of pregnancy in reptiles. Estimates of litter metabolism were obtained by measuring maximum embryo metabolism, using an in vitro technique and multiplying embryo V̇o2 by litter size. These results suggest that others have overestimated the physiological cost of pregnancy in reptiles because maximum litter V̇o2 has been underestimated. Others have suggested that viviparity is an expensive mode of reproduction because the physiological cost of supporting a litter is an important component of an individual's reproductive effort. Data presented here support the alternative hypotheses that the cost of supporting a litter is not high and constitutes a small fraction of the energy apportioned into reproduction. © 1992 Wiley‐Liss, Inc.
Modulation of meiotic arrest in mouse oocytes by guanyl nucleotides and modifiers of G‐proteins
Authors: Downs Stephen M. , Buccione Roberto , Eppig John J. 
Published: June 2005

AbstractGuanyl nucleotide binding‐proteins, or G‐proteins, are ubiquitous molecules that are involved in cellular signal transduction mechanisms. Because a role has been established for cAMP in meiosis and G‐proteins participate in cAMP‐generating systems by stimulating or inhibiting adenylate cyclase, the present study was conducted to examine the possible involvement of G‐proteins in the resumption of meiotic maturation. Cumulus cell‐free mouse oocytes (denuded oocytes) were maintained in meiotic arrest in a transient and dose‐dependent manner when microinjected with the nonhydrolyzable GTP analog, GTPγS. This effect was specific for GTPγS, because GppNHp, GTP, and ATPγS were without effect. Three compounds, known to interact with G‐proteins, were tested for their ability to modulate meiotic maturation: pertussis toxin, cholera toxin, and aluminum fluoride (AlF4−). Pertussis toxin had little effect on maturation in either cumulus cell‐enclosed oocytes or denuded oocytes when meiotic arrest was maintained with dibutyryl cAMP (dbcAMP) or hypoxanthine. Cholera toxin stimulated germinal vesicle breakdown (GVB) in cumulus cell‐enclosed oocytes during long‐term culture, but its action was inhibitory in denuded oocytes. AlF4− stimulated GVB in both cumulus cell‐enclosed oocytes and denuded oocytes when meiotic arrest was maintained with hypoxanthine but was much less effective in dbcAMP‐arrested oocytes. In addition, AlF4− abrogated the inhibitory action of cholera toxin in denuded oocytes and also that of follicle‐stimulating hormone (FSH) in cumulus cell‐enclosed oocytes. Cholera toxin or FSH alone each stimulated the synthesis of cAMP in oocyte‐cumulus cell complexes, whereas pertussis toxin or AlF4− alone were without effect. Both cholera toxin and AlF4− augmented the stimulatory action of FSH on cAMP. These data suggest the involvement of guanyl nucleotides and G‐proteins in the regulation of GVB, although different G‐proteins and mediators may be involved at the oocyte and cumulus cell levels. Cholera toxin most likely acts by ADP ribosylation of the α subunit of Gs and increased generation of cAMP, whereas AlF4− appears to act by antagonizing a cAMP‐dependent step.
Extracellular and intracellular acid‐base regulation in crustaceans
Authors: Wheatly Michele G. , Henry Raymond P. 
Published: June 2005

AbstractThis article attempts to review mechanisms of intra‐ (ICF) and extracellular fluid (ECF) acid‐base balance and the contribution each makes to whole animal acid‐base homeostasis in an evolutionary progression of crustaceans (marine, freshwater, semi‐ and fully terrestrial). ICF pH (pHi) is regulated to preserve the functional integrity of enzymes involved in cell metabolism. The ECF is the intermediary between cellular acid/base production and whole animal exchange at the primary epithelia, the gills, and antennal gland. In vivo regulation of pHi is discussed under selected environmental conditions. Compensatory mechanisms include intracellular buffering and transmembrane exchange of acidic/base equivalents including primarily an Na + /H + /HCO3 −/Cl− mechanism and an Na + /H + exchanger. Acid‐base values and regulation in the ECF (which may be subcompartmented in selected tissues) differ in aquatic versus terrestrial species. The latter have higher PCO2 (and lower pH) associated with reduced ventilation due to the higher O2 capacitance of air. Correspondingly they can regulate ECF pH (pHe) by respiratory control of PCO2; terrestrial species also depend upon mobilization of exoskeletal CaCO3 to buffer protons. In aquatic species the primary mechanism of acid‐base regulation is via electroneutral ion exchangers (Na +/acidic equivalent; Cl −/basic equivalent) primarily at the branchial epithelium but also apparent in the renal tubule in species that produce dilute urine (hyperosmo/ionoregulators). Evidence is presented for dynamic regulation of unidirectional branchial and renal ion fluxes for purposes of acid‐base regulation. Quantitatively the antennal gland typically contributes only 10% of the overall response. Stoichiometrically, whole animal acidic/basic equivalents exchanged at these epithelia originate predominantly in the ICF compartment (50‐‐95%). Future perspectives emphasize the need to better understand how pH compensation or in some cases tolerance is related to cellular function. © 1992 Wiley‐Liss, Inc.
Prostaglandin E2 and reproduction in the male crested newt, Triturus carnifex (Laur.)
Authors: Gobbetti Anna , Zerani Massimo 
Published: June 2005

AbstractPlasma prostaglandin E2 (PGE2) and sex hormones (progesterone, androgens, and 17β‐estradiol) were determined in the male crested newt, Triturus carnifex, during the annual sexual cycle. In vivo experiments were carried out to study the effects of PGE2 on plasma sex hormones during prereproduction, reproduction, and postreproduction; contemporaneously, in vitro experiments were performed to study the effects of PGE2 on the testicular release of sex hormones. The effects of one week's captivity on PGE2 and sex hormones was also evaluated. Plasma PGE2 increases in autumn, during the recovery of gonad and secondary sexual characteristics; it peaks in January, at the start of reproduction, and decreases during reproduction to peak again in April, at the end of reproduction. Plasma sex hormones show trends similar to those found in previous studies. In autumn, PGE2 and androgen patterns are positively correlated, whereas the April PGE2 peak coincides with a drop in plasma androgens. In vivo and in vitro experiments suggest the causal relation between PGE2 and androgens. When injected in prereproductive newts or added to cultured testis in this period, PGE2 increases androgen production. An opposite in vivo and in vitro effect is obtained during reproduction. These findings suggest that PGE2 is involved in inducing the autumnal recovery of gonad and secondary sexual characters (through the stimulation of androgen production), and in terminating the breeding processes (through the inhibition of androgen production and/or clearance). Finally, captivity causes a decrease of plasma PGE2, androgens, and estradiol, a phenomenon quite common in captive vertebrates. © 1992 Wiley‐Liss, Inc.
Immunocytochemical analysis of the association of bovine oviduct‐specific glycoproteins with early embryos
Authors: Boice Melinda Lee , Mavrogianis Patricia A. , Murphy Clifford N. , Prather Randall S. , Day Billy N. 
Published: June 2005

AbstractThe bovine oviductal epithelium synthesizes and secretes a class of oviduct‐specific glycoproteins that is present in the luminal fluid when fertilization and early embryonic development occur. The objective of this study was to determine if these characterized glycoproteins become associated with oviductal embryos. Ovarian ova and oviductal embryos were recovered from super‐ovulated cows at 72 h after onset of estrus. Eggs were fixed in 3% paraformaldehyde‐1% gluteraldehyde and subsequently embedded in Lowicryl K4M. Sections (1 μm) were processed for peroxidase‐antiperoxidase immunocytochemistry. Immunolabeling was not detected in any region of ovarian ova. Oviductal embryos, regardless of cleavage stage, exhibited immunoperoxidase staining localized within their zona pellucidae. Sections (100 nm) obtained from a 4‐ and an 8‐cell embryo were also subjected to colloidal gold immunoelectron microscopy to determine conclusively the subcellular distribution of the oviduct‐specific glycoproteins. Gold particles were distributed uniformly throughout the width of the zona pellucida. Also, immunoreactivity was observed associated with flocculent material in the perivitelline space and with the vitelline membrane. These results indicate that the bovine oviduct‐specific secretory glycoproteins become associated with oviductal embryos. This association may be biologically important to the developing embryo. © 1992 Wiley‐Liss, Inc.
Ovarian stretch signals trigger volume increase in the magnocellular preoptic nuclear region in the brain of the catfish, Clarias batrachus (Linn.)
Authors: Deshmukh Makrand K. , Krishna N. S. Rama , Subhedar Nishikant 
Published: June 2005

AbstractIntraovarian pressure of 10, 20, and 30 mm Hg magnitude was administered in the fish, Clarias batrachus, and the volume changes undergone by the magnocellular preoptic nucleus (NPO) were examined using serial brain sections of treated and sham‐treated fish. The treatment consistently resulted in statistically significant (P<0.001) increase in the volume of the NPO; a rise of up to 46.48% was observed in the paraventricular subdivision of the NPO following 20 mm Hg intraovarian pressure administration. The response was abolished following transection of the spinal cord. The results suggest the occurrence of an afferent pathway from the ovary capable of transducing stretch signals and conveying action potentials to the NPO via the spinal cord. The possibility that the pathway might serve as an afferent component in the spawning reflex is examined. © 1992 Wiley‐Liss, Inc.
Vitellogenesis level and induction of maturation in the ovary of the Blue Gourami Trichogaster trichopterus (Anabantidae, Pallas, 1770)
Authors: Degani Gad , Boker Rachel 
Published: June 2005

AbstractThe effectiveness of 17α‐hydroxyprogesterone (17‐P), 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (17,20‐P), and carp gonadotropin (cGtH) in inducing germinal vesicle breakdown (GVBD) was examined in vitro in female blue gourami Trichogaster trichopterus (Pallas, 1770) as a model of multispawning, asynchronic fish. Induced GVBD was measured at three stages of ovary development: low (<25%), intermediate (≈30%), and high vitellogenesis (>45%).The size of oocytes increased rapidly from the chromatin nucleolar stage to the stage of vitellogenesis, but little more thereafter. The effect of the hormones was to pass the oocytes from stage to stage, with very little effect on the size during maturation.Only slight influence was detected on ovaries with a low percentage of vitellogenesis by treatment with 17‐P, 17,20‐P, cGtH, or any combination of these hormones.In the intermediate percentage range, cGtH effected an increase in vitellogenesis, while cGtH in combination with 17‐P or 17,20‐P induced a low percentage of GVBD.In ovaries with a high percentage of vitellogenesis (>45%), in vitro treatment with 100 ng/ml cGtH had little effect, 300 ng/ml cGtH significantly increased vitellogenesis, and 600 ng/ml induced a low level of GVBD. In vitro treatment with 300 ng/ml cGtH and various concentrations of 17‐P caused a significant increase in the percentage of oocytes in GVBD, and even induced ovulation. Various combinations of cGtH, 17‐P, and 17,20‐P significantly increased the percentage of oocytes in maturation, and also caused ovulation.A model of the relationship between sexual behavior, ovary development, and control by MIS and GtH in this type of fish is discussed. © 1992 Wiley‐Liss, Inc.