bluuebunny/crossref_metadata_2025_split huggingface dataset:
Onset of DNA synthesis in experimentally activated ascidian eggs
Authors: Patricolo E. , Mansueto C. 
Published: June 2005

AbstractDNA synthesis was studied autoradiographically in unfertilized ascidian eggs (Ascidia malaca and Ciona intestinalis) that had been artificially activated by a K+‐free external medium or a Ca‐ionophore. Naked eggs of A. malaca were incubated in K+‐free seawater that contained [3H]‐thymidine for 30 min, and naked eggs of C. intestinalis were incubated in seawater supplemented with a Ca‐ionophore and [3H]‐thymidine for 15 min. The observations revealed limited activation in eggs treated with K+‐free seawater. Activation consisted of surface modifications and the onset of DNA synthesis. Incorporation of [3H]‐thymidine was detected in female nuclei of treated eggs which had not ejected their polar bodies. In eggs treated with the Ca‐ionophore, a known activating agent, the rate of incorporation of [3H]‐thymidine was higher and nuclear duplication was also observed. Comparison of activation under the two different sets of artificial conditions indicated that, in K+‐free medium, the early calcium‐dependent events, such as deformation of egg shape, extrusion of the polar bodies, and ooplasmic segregation, do not occur, while DNA synthesis is initiated. The results are discussed on the basis of the hypothesis that, in Ascidians, egg‐activation events are only partly regulated by an intracellular increase in levels of calcium ions. DNA synthesis appears to be an independent process that is initiated by changes in the egg plasma membrane. © 1994 Wiley‐Liss, Inc.
Combined gonadal and photic influences on 2‐[125I] iodomelatonin‐binding level changes in some brain areas of the quail
Authors: Canonaco Marcello , Tavolaro Renata , Facciolo Rosa Maria , Artero Cristina , Franzoni Maria Fosca 
Published: June 2005

AbstractQuantitative receptor autoradiography was used to study the binding of 2‐[125I] iodomelatonin in the brain of the castrated and gonadally intact male Japanese quail Coturnix japonica exposed to both long‐ and short‐day photoperiod cycles. The distribution study displayed that these conditions were responsible for a heterogeneous binding pattern as shown by elevated receptor levels being located in visual brain centers, such as the stratum opticum, nucleus pretectalis, and nucleus geniculatus lateralis, pars ventralis, while lower values were found in the nucleus lateralis hypothalami and nucleus isthmi pars magnocellularis. Closer examination of the 2‐[125I] iodomelatonin–binding pattern following the different gonadal and photic influences showed that combination of the gonadally intact condition and a 16L:8D (long‐day) photoperiod cycle was required for the greater binding changes. These differences occurred in brain sites such as the area preoptica, paleostriatum primitivum, and nucleus ectomamillaris. Saturation binding studies, which were carried out only in some of the above areas, revealed that the combined gonadal and photic‐induced changes are basically due to the modifications of total number of binding sites. The importance of a gonadal steroid modulatory role in the photic‐dependent melatonin binding activity suggests that other types of neuronal mechanisms might be involved in the regulation of neuroendocrine and socio–sexual behaviors in nonmammalian vertebrates. © 1994 Wiley‐Liss, Inc.
Myosin isoforms and their subunits in the lungfish Protopterus annectens: Changes during development and the annual cycle
Authors: Chanoine Christophe , El‐Attari Ahmed , Guyot‐Lenfant Michèle , Ouedraogo Lazare , Gallien Claude‐Louis 
Published: June 2005

AbstractMyosin isoforms and their light and heavy subunits were analyzed, in a comparison with the profile of myosin ATPase during the development and annual cycle of the African lungfish Protopterus annectens. Axial muscle of the larvae contained three isoforms of larval myosin. In adult animals, larval isomyosins were shown to coexist with small amounts of fast isomyosins in axial muscle. By contrast, fin muscles displayed essentially the fast isomyosins and a slow myosin isoform. No significant differences were noted in myosin content between swimming, cocooning, and water‐readapted animals. Larval and fast myosin isoforms were composed of two different heavy chains, HCI and HCf, respectively, in association with fast light chains. The slow myosin isoform was characterized by a distinct heavy chain, HCs, which was associated with two slow light chains. Analysis of the profile of myosin ATPase revealed only type IIC fibers in the axial muscles of larvae, while the adult muscles were composed of type IIC fibers in the central part and adult type IIA, IIB, and I fibers in the peripheral part. This study shows that P. annectens resembles the neotenic urodelan amphibian Ambystoma mexicanum at the level of the distribution of muscle fiber types and the expression of myosin isoforms. © 1994 Wiley‐Liss, Inc.
Effects of impregnation on maturation, spawning, and ecdysis of female shrimp Penaeus indicus
Authors: Peeters L. , Diter A. 
Published: June 2005

AbstractImpregnation of females (i.e., spermatophore transfer) is known to occur soon after ecdysis in closed thelycum penaeids, while no sign of female maturation is visible yet. The influence of impregnation on maturation, spawning, and intermoult duration was assessed in Penaeus indicus females with or without unilateral eyestalk ablation. Impregnation, when occurring in unablated females, was found to significantly increase the percentages of maturing females (93–100% vs. 40–47%) and spawning females (86–100% vs. 20%), the number of spawns per female (1.46–1.91 vs. 0.26–0.40), and the intermoult duration (13.16–13.53 vs. 11.36–11.86 days). No remnants of impregnation was detected since its effects on the various parameters studied were restricted to the moult cycle where it occurred. Unilateral eyestalk ablation induced effects similar to those of impregnation on the reproduction parameters studied, but did not extend the length of the moult cycle. Impregnation of females that have been previously unilaterally ablated induced no change in any parameter studied including the intermoult duration. These findings suggest that impregnation interacts with certain physiological processes controlled by the X organ‐sinus gland neuroendocrine complex, located in the eyestalk. © 1994 Wiley‐Liss, Inc.
Experimental conditions for oocyte maturation in the zebrafish, Brachydanio rerio
Authors: Selman Kelly , Petrino Teresa R. , Wallace Robin A. 
Published: June 2005

AbstractAn in vitro protocol was established for studying oocyte maturation in the zebrafish, Brachydanio rerio. When appropriate size follicles (0.575–0.625 mm diameter) were incubated at 26°C for 8–24 h in 60% Leibovitz L‐15 medium containing 1 μg/ml of 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (DHP), their oocytes underwent maturation. Under these conditions, but in the absence of exogenous steroid, control follicles remained arrested in prophase I. Germinal vesicle breakdown was used to indicate that maturation had occurred, and this event was readily visible in living follicles viewed through a dissecting microscope. Furthermore, as maturation takes place, the rather opaque prematurational follicles became translucent. In the process of establishing a reliable in vitro bioassay for oocyte maturation in the zebrafish, we compared the effects of gonadotropin (human chorionic gonadotropin) and a steroid hormone (DHP) on the in vitro stimulation of maturation, over a range of doses and incubation times. Finally, the relative effectiveness of several steroids and their metabolites in eliciting oocyte maturation in vitro was determined, and DHP appeared to be most effective. © 1994 Wiley‐Liss, Inc.
Pathways of regeneration of Haller's sensory organ during the life cycle of the tick Hyalomma asiaticum
Authors: Belozerov Valentin N. , Leonovich Sergei A. 
Published: June 2005

AbstractA study of regeneration in nymphs and adults of the Asiatic desert tick, Hyalomma asiaticum, from which forelegs had been amputated during the previous instar, revealed that regenerated Haller's sensory organs exhibited significant changes in structure. Adult regenerates possessed atavistic features in terms of the number and topography of different sensillar types. Regularity in these changes was similar to that demonstrated in regenerates of Ixodes ricinus (Leonovich and Belozerov [1992] Exp. Appl. Acarol., 15: 59–79). Nymphal regenerates, by contrast, had larval features of the parent species. An hypothesis is presented about the ontogenesis of the complete, peripheral, polymodal sensory organ as a process in which the initial cell differentiation of cells begins at different starting points. © 1995 Wiley‐Liss, Inc.
Fluctuations in the biosynthetic activity of the prothoracic gland in recessive trimolters of the silkworm, Bombyx mori: Their modulation by juvenile hormone and physiological significance
Authors: Gu Shi‐Hong , Chow Yien‐Shing , Lin Fei‐Jann 
Published: June 2005

AbstractChanges in the steroidogenic competence of prothoracic glands and their modulation by juvenile hormone (JH) were examined in recessive trimolters(rt)of the silkworm, Bombyx mori. These rt mutants have four larval instars rather than the five larval instars of normal silkworms. A small peak of prothoracic gland activity was found to occur during the early stage of the last (fourth) larval instar. The activities of both the prothoracic gland and the corpora allata (CA) were, however, greatly inhibited during the third instar after the third instar larvae have been treated with an imidazole compound (KK‐42). No small peak of prothoracic gland activity was detected during the early stage of the last instar in these treated larvae. The pattern of secretion from the prothoracic gland during the third instar was not significantly affected when hydroprene was applied to the KK‐42‐treated larvae during the prolonged third instar. However, the same small peak of activity, as found in untreated rt larvae, was detected during the early last instar. A model was developed from the results of the present study which clearly shows how the slight fluctuations in the activity of the prothoracic gland are regulated. By treating newly ecdysed last instar larvae with KK‐42 and by the addition of 20‐hydroxyecdysone to the food supplied to these larvae, we conclude that the decrease after small increase in the ecdysteroid titers and subsequent low ecdysteroid levels during the early last larval instar play an important role in initiating the decline of the JH biosynthetic rate and in directing precocious metamorphosis. © 1995 Wiley‐Liss, Inc.
Regulation of ovarian recrudescence: Different effects of corticotropin in small and large female lizards, Anolis carolinensis
Authors: Summers Cleff H. 
Published: June 2005

AbstractSubcutaneous injection of 50 mU of ovine adrenocorticotropic hormone (ACTH) stimulates an increase in plasma corticosterone in Anolis carolinensis, after 30 min equivalent to maximum levels of stress‐induced plasma corticosterone. Plasma corticosterone returned to noninjection levels by 4 h. Injection of 50 mU ACTH, daily at 1630, into female A. carolinensis treated with stimulatory temperature and light, effected ovarian recrudescence; however, the effect depended upon the size of the lizard. Ovarian growth in small lizards (≥2.6 g) was inhibited by ACTH. In these animals ovaries regressed in size and oviducts remained quiescent. In larger females (<2.6 g) ovarian recrudescence continued in spite of ACTH administration and the consequent stimulation of higher levels of plasma corticosterone. Oviducts were significantly heavier in this group as well, indicating that ovaries were not only larger and heavier, but were secreting estrogens as well. The results of these experiments suggest that differently sized females of this species respond to hormones of the adrenal axis differently, and perhaps to stress as well. Specifically, Whereas ACTH administration inhibits ovarian growth in small anoles as it does in other vertebrates, it appears to have no effect or to enhance ovarian growth in large female A. carolinensis. © 1995 Wiley‐Liss, Inc.
Tubulin and microtubule‐associated protein pools in unfertilized and fertilized eggs of the trout Oncorhynchus mykiss
Authors: Farías Gustavo , González Mauricio , Maccioni Ricardo B. 
Published: June 2005

AbstractA molecular characterization of tubulin and microtubule‐associated proteins (MAPs) along with their intracellular pool distributions in both unfertilized and fertilized oocytes of the trout Oncorhynchus mykiss was carried out. In vitro assembly of microtubular proteins was obtained by cycles of assembly‐disassembly and by taxol‐induced polymerization, thus allowing identification of the protein components of isolated microtubules from the oocyte. Extraction procedures were developed in order to separate molecular components of the egg vitelum prior to purification steps. The use of antibodies that specifically tag tubulin and a set of site‐directed probes against repetitive binding sequences on MAPs provided data on the presence of tubulins and enabled the identification of an 85‐kDa protein that shares common functional epitopes with mammalian MAPs. An enzyme‐linked immunosorbent assay analysis of the free soluble tubulin pools revealed a significant decrease in the pool extent during fertilization as compared with unfertilized oocytes controls. Interestingly, this decrease in free tubulin in the fertilized trout oocyte appeared to be accompanied with a concomitant increase of the assembled tubulin pools. Within the context of the known effects of heat shock in oocyte fertilization, temperature changes from 4 to 26.5°C of fertilized eggs resulted in a transient increase in the soluble tubulin pools during the initial 5‐min heat incubation, decaying after 10 min treatment, to reach at 15 min the levels of soluble tubulin pools of untreated controls. Total tubulin pools remained constant during the heat incubations of fertilized eggs. The distribution of MAPs pools in the oocyte was also investigated using the specific immunological probes. In contrast to tubulin no major differences were found between free MAPs pools of the fertilized oocytes as compared with unfertilized controls. However, heat shock treatment of fertilized oocytes also induced a transient increase in free MAP pools during the first 5 min followed by a mobilization of immunoreactive MAP components from the soluble to the assembled pools. © 1995 Wiley‐Liss, Inc.
Photoperiod‐induced changes in the proteins secreted by the male genital tract of the rodent Octodon degus
Authors: Carballada Rosa , Bustos‐Obregón Eduardo , Esponda Pedro 
Published: June 2005

AbstractThe proteins secreted by the male genital tract were analyzed in the seasonally breeding rodent Octodon degus. The protein patterns from the fluids collected from sexually active animals were compared with those from animals in resting period, with others which were previously castrated, and with castrated animals which received testosterone replacement treatment. Fluids from cauda epididymides (CE), seminal vesicles (SV) and prostate glands (PG) were collected, and analyzed by polyacrylamide gel electrophoresis followed by different staining methods and densitometry. Modifications were detected in the protein patterns of resting or castrated animals. In CE fluid, the decrease of one protein band (45 Kda) and the uprising of another (210 Kda) were recognized after castration. In animals during resting period the changes were not as marked as in castrated animals. SV secretion demonstrated a similar response to resting phase and castration, because Protein SVS I (200 Kda) decreased or were not observed when these conditions occurred. PG fluid proteins were also modified after castration. In general, the more severe changes in the protein spectrum were induced by castration, despite radioimmunoassay showing that testosterone fall is even higher in resting period animals than in those castrated. Testosterone replacement resulted in recovery of a protein profile which is very similar to that of sexually active males. Results suggest that the androgenic control of male tract secretions would be rather different in this seasonal hystrichomorph when compared to the regulation system described for myomorph rodents. © 1995 Wiley‐Liss, Inc.
Cortisol stimulates the size and number of mitochondrion‐rich cells in the yolk‐sac membrane of embryos and larvae of tilapia (Oreochromis mossambicus) in vitro and in vivo
Authors: Ayson Felix G. , Kaneko Toyoji , Hasegawa Sanae , Hirano Tetsuya 
Published: June 2005

AbstractThe effect of cortisol and thyroid hormones on the activity of mitochondrion‐rich (MR) cells in the yolk‐sac membrane of tilapia (Oreochromis mossambicus) embryos and larvae was investigated. MR cells were identified by the fluorescent mitochondrial stain DASPEI. Yolk‐sac membranes from 4‐day‐old embryos in fresh water (FW) were incubated for 24 h in medium supplemented with cortisol, thyroxine (T4), or triiodothyronine (T3). Treatment with cortisol at 0.1 μ/ml and higher significantly increased the population of MR cells and the intensity of fluorescence compared with the control, whereas MR cell size was not affected. Treatments with T4 and T3 did not affect MR cell density, size, or intensity of fluorescence.Four‐day‐old embryos in FW were immersed for 10 days in FW supplemented with cortisol, T4, or T3. A significant increase in MR cell size was observed starting on day 3 after treatment with 100 μ/ml cortisol. Treatment with lower doses of cortisol produced increases in the cell size on later days. Density of MR cells was significantly increased only on day 9. Treatment with T4 produced inconsistent results. Treatment with T3 did not affect MR cell size or density at any time. None of the three hormones affected the intensity of fluorescence of MR cells. The stimulatory activity of cortisol on MR cells in the yolk‐sac membrane suggests that cortisol, present in the yolk of tilapia embryos and larvae, may be involved in osmoregulation during the early life stages of fish. © 1995 Wiley‐Liss, Inc.
Effects of castration on antler growth in fallow deer (Dama dama L.)
Authors: Kierdorf Uwe , Kierdorf Horst , Knuth Susanne 
Published: June 2005

AbstractMorphology and histological structure of antlers grown after castration (performed on March 25) were studied in six young fallow bucks. In the year after castration, antlerogenesis occurred during the species‐specific time span, and the shape of the antlers, which remained permanently in velvet, was normal. During a cold period in December/January, the distal parts of the antlers suffered from frostbite and were subsequently detached. The process of sequestration was similar to that leading to normal antler casting. The sequestration sites were soon covered with skin, but (limited) regrowth of antler tissue from the stumps was not observed before late April/early May, i.e., the time of normal antler regeneration. Simultaneously, growth of knobby protuberances started on the surface of the antlers. Histological analysis of biopsies taken on December 20 in the year after castration revealed that the central parts of the antlers consisted of cancellous lamellar bone with mainly secondary osteons. Peripheral to this, the bone tissue (forming the protuberances) was of a more immature nature and exhibited larger intertrabecular spaces. The outermost layer consisted of woven bone formed by intramembranous ossification from the periosteum and was undergoing active growth and remodeling at the time of biopsy. Thus, bone formation at these sites occurred during a period when no antler growth is observed in normal fallow bucks. The velvet covering the bony protuberances was of normal appearance. © 1995 Wiley‐Liss, Inc.
Responses to chronic hypoxia in embryonic alligators
Authors: Warburton Stephen J. , Hastings Dulynn , Wang Tobias 
Published: June 2005

AbstractTo investigate developmental responses to chronic hypoxia, we incubated alligator eggs at 17% O2 and 21% O2 for the entire course of embryonic development and for 5 months post‐hatching. Hypoxic‐incubated alligators hatched later and at a smaller size. Hematocrit was significantly higher in hypoxic‐incubated animals immediately post‐hatch. Allosteric modification of hemoglobin oxygen affinity did not appear to play a role in the adaptation to hypoxia, given equal nucleotide triphosphate‐to‐hemoglobin ratios in the hypoxic and normoxic groups. When acutely exposed to 21% O2, hypoxic‐incubated alligators maintained oxygen consumption relative to their normoxic siblings despite their lower mass. © 1995 Wiley‐Liss, Inc.
Vitellogenins of Oreochromis niloticus: Identification, isolation, and biochemical and immunochemical characterization
Authors: Buerano Corazon C. , Inaba Kazuo , Natividad Filipinas F. , Morisawa Masaaki 
Published: June 2005

AbstractTwo native forms of vitellogenin (EIP1 and EIP2) were identified in the plasma of Oreochromis niloticus. They were present in females and were estrogen‐inducible in males. Both were phosphoglycolipoproteins and both immunoreacted with the antiserum raised against egg proteins. Two prominent bands (EIpp1 and EIpp2; corresponding to 185 and 120 kDa, respectively), observed on sodium dodecyl sulfate‐polyacrylamide gels, were induced by estradiol treatment of males and immunoreacted with the antiserum against egg proteins. EIP1 and EIP2 were isolated by precipitation with Mg2+ ions and ethylenediamine tetraacetic acid, preparative polyacrylamide gel electrophoresis, and electroelution. During purification the fractions containing EIP1 and EIP2 also retained EIpp2 and EIpp1, respectively. Immunoblot analyses using affinity‐purified antibodies against EIP1, EIP2, EIpp1, and EIpp2 confirmed that EIP1 and EIP2 were at least composed of EIpp2 and EIpp1, respectively. These results suggest that at least two immunochemically different proteins are induced and are secreted into the blood to serve as vitellogenin and to provide a source of nutrient for the developing embryo of Oreochromis niloticus. © 1995 Wiley‐Liss, Inc.
Calcium, sulfur, and zinc distribution in normal and arthritic articular equine cartilage: A synchrotron radiation‐induced X‐ray emission (SRIXE) study
Authors: Rizzo R. , Grandolfo M. , Godeas C. , Jones K. W. , Vittur F. 
Published: June 2005

AbstractCalcium, sulfur, and zinc content in normal and arthritic equine cartilage have been studied by synchrotron radiation‐induced X‐ray emission (SRIXE). Ranging from the superficial to the columnar zone of the normal tissue, calcium and zinc concentrations are increasingly higher, whereas sulfur is at its highest concentration in the transitional zone. In the arthritic tissue, calcium concentration is at its maximum in the transitional zone, whereas zinc and sulfur distributions are relatively homogeneous. Sulfur concentration in arthritic cartilage is reduced to about one‐third with respect to that in normal tissue. The possibility that zinc concentration reflects the distribution of the zinc‐containing enzyme alkaline phosphatase is presented. © 1995 Wiley‐Liss, Inc.