bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intra‐allantoic implantation: An alternative to the classical chorioallantoic membrane grafting technique
Authors: Krukowski Marilyn , Iler H. Darrell , Kahn Arnold J. 
Published: June 2005

AbstractA grafting method is described wherein donor tissue is partially inserted into a small slit cut into the proximal portion of the allantoic membrance of chick embryos aged 3.5–5.5 days. Cartilaginous bone rudiments handled in this manner readily vascularize, grow significantly, and begin osteogenesis within a 3‐day incubation period. Compared to traditional chorioallantoic membrane grafting, usually done with hosts aged 9–12 days, the proposed intra‐allantoic technique (1) greatly increases the period in which grafted materials are in residence (potentially up to 15 days) and (2) permits assessment of the host response of relatively young embryos.
Cytogeographical studies of the cell surface in Paramecium caudatum
Authors: Watanabe Tsuyoshi 
Published: June 2005

AbstractIn paramecium caudatum, distribution of two kinds of cortical units, i.e., one‐cilium units and two‐cilium units, was compared to the area of deciliation during sexual reproduction. Two‐cilium units, which were confirmed by the presence of 2 ciliary stubs after total chemical deciliation, are distributed on the anterior‐left (cell's left) field and circumoral field of the ventral surface. Near the anterior tip region, two‐cilium units were observed on both sides of the suture line. In contrast with this, the postero‐ventral half of the cell and the dorsal surface are composed exclusively of one‐cilium units. When the area of local deciliation during sexual reproduction was compared with the area containing two‐cilium units, no correlation was observed except at the anterior tip region.
Reversible stage‐specific embryonic inhibition mediated by the presence of adults in the annual fishNothobranchius guentheri
Authors: Inglima Kenneth , Perlmutter Alfred , Markofsky Jules 
Published: June 2005

AbstractNothobranchius guentheri, an annual fish from East Africa, is found in temporary ponds, pools, and streams that dry seasonally. The populations survive the dry season in the form of thickly chorionated embryos encased in the muddy substrate. WhenN. guentheriadults are allowed to spawn in the laboratory at 24.0 ± 1°C and the fertilized eggs are collected shortly afterwards, formation of the embryonic axis normally occurs within 5 to 11 days. However, examination of embryo populations obtained from unaerated aquaria after uninterrupted spawning periods of up to 2 or 3 months revealed only rare instances of embryogenesis. The overwhelming majority of embryos proceeded no further than the dispersed cell phase (diapause I, stage 20). Spawning was found to be continuous throughout these prolonged periods and the possibility of adult predation was eliminated. While low PO2has been determined to be a factor contributing to the duration of diapause I, determinations of PO2, PCO2, pH, free ammonia and bacterial flora indicated that aquarium conditions could support embryogenesis. Only embryos at stages 20 and 32, both being stages of naturally occurring diapause, could be inhibited. The inhibitory effect was dependent on the adult density and was diminished with aeration. It is proposed that, in nature, the adult‐produced inhibitory factor may be useful in the conservation and augmentation of the embryonic reserve which is the mainstay of annual fish populations in tropical areas of alternating rainy and dry seasons.
Ultrastructural localization of gonadotropin and luteinizing hormone releasing hormone in the pituitary gland of a teleost fish (the platyfish)
Authors: Margolis‐Kazan Henrietta , Peute Jan , Schreibman Martin P. , Halpern Leslie R. 
Published: June 2005

AbstractImmunoreactive luteinizing hormone releasing hormone (irLHRH) and immunoreactive gonadotropin (irGtH) are demonstrated in the pituitary gland of a teleost fish (Xiphophorus maculatus, the platyfish) at the ultrastructural level. Using an immunoperoxidase procedure, irGtH and irLHRH are specifically localized over the secretory granules of both gonadotropes and some cells of the pars intermedia (PI). All other pituitary cell types lack immunoreactive material. A concept of LHRH receptors on gonadotrope granules is discussed and a new function for a class of PI cells is suggested.
Hormone‐cytoplasmic interactions controlling sperm nuclear decondensation and male pronuclear development in starfish oocytes
Authors: Schuetz Allen W. , Longo Frank J. 
Published: June 2005

AbstractNumerous highly condensed sperm nuclei were present in the cytoplasm of starfish oocytes fertilized at the germinal vesicle stage. Decondensation of sperm nuclei and formation of male pronuclei and asters followed treatment of such fertilized oocytes with meiosis‐inducing hormone 1‐methyladenine (1‐MA). Transformation of sperm nuclei was asynchronous, occurred only after germinal vesicle breakdown (GVBD), and was associated with characteristic clearing of the adjacent cytoplasmic organelles. GVBD and sperm nuclear changes were both inhibited when dinitrophenol was added to previously fertilized GV‐intact oocytes. Results demonstrate that polyspermy occurs readily in immature oocytes and that 1‐MA plays a key role in establishing the block to polyspermy. Furthermore, the factors necessary for sperm nuclear decondensation and pronuclear development do not exist in the cytoplasm of immature oocytes but arise following dispersal of germinal vesicle contents into the cytoplasm. Thus, absence of embryonic development in fertilized GV‐intact oocytes is linked to a lack of both oocyte and sperm nuclear differentiation rather than to a lack of sperm entry into the cytoplasm.
Morphogenetic effect of rotated skin cuffs on tail regeneration in Plethodon cinereus
Authors: Dinsmore Charles E. 
Published: June 2005

AbstractAs an epimorphic system, the urodele tail has much in common with the urodele limb, relative to tissue components. In an effort to elucidate potentially similar functions of the skin during regeneration, two procedures which have been shown to be highly disruptive of limb morphogenesis were performed on the tail. In the first, cuffs of tail skin were rotated 180° about the long axis of tails in Plethodon cinereus. Subsequent amputation through the rotated cuffs produced regenerates at a normal rate which were also normal in both internal architecture and skin gland distribution.In a second series, cuffs of tail skin were rotated 90° about the dorso‐ventral axis of the tail, such that the dorsal red stripe encircled the tail. Upon amputation through the middle of the cuff, the stump skin presented an excusively dorsal surface which, nevertheless, had no effect upon the morphogenetic success of the regenerate.These data therefore indicate that a tissue, such as skin, may be inconsistent in its morphogenetic influence among epimorphic fields within the same organism. It is not clear whether these results reflect differences in field behavior or in absolute tissue potential determined by the field of origin. A tissue hierarchy of morphogenetic influence within and among epimorphic fields is suggested as a preliminary framework within which to coordinate such information.
The anovulatory hamster: A comparison of the effects of short photoperiod and daily melatonin injections on the induction and termination of ovarian acyclicity
Authors: Stetson Milton H. , Hamilton Brian 
Published: June 2005

AbstractCyclic female hamsters were rendered anovulatory by daily subcutaneous melatonin injections (25 μg/0.1 ml oil) in 29 days or by transfer to a short light cycle, LD 6:18 (lights 1000‐1600 hrs) in 33 days. Estrous cyclicity was reinitiated in these animals in 44 or 45 days following cessation of melatonin injections or transfer to long light cycles (LD 14:10, lights 0600‐2000 hrs), respectively. Exposure of both groups to LD 6:18 after reinitiation of estrous cyclicity caused a second cessation of ovulation in 75 (melatonin group) or 61 (short light cycle group) days. Thus, although both treatments disrupted estrous cyclicity for nearly 6 weeks, this was not sufficient to induce photorefractoriness (failure to respond to short light cycles with continued estrous cyclicity). Rather, every animal responded to LD 6:18 and ceased ovulating. Melatonin‐induced anovulatory hamsters showed daily gonadotropin release patterns identical to those reported in hamsters in other anovulatory states (lactating, prepubertal, and photoinduced anovulatory hamsters); that is, peak LH and FSH release at 1700 hrs daily.
Control mechanisms of amino acid‐mediated cell volume regulation in salinity‐stressed molluscs
Authors: Pierce Sidney K. , Amende Lynn M. 
Published: June 2005

AbstractThe mechanisms of cell volume regulation in molluscs have been examined in detail in only a few species. While generalizations must be made with some caution until additional species have been tested, the following mechanism has emerged. When stressed with a decreased external salinity the cells of osmoconforming bivalves swell for a period of time and then recover toward the original cell volume. The volume recovery is effected by an efflux of intracellular free amino acids which act as osmotic solute. While the drop in external osmolality initiates the efflux, the duration of the efflux (restoration of normal amino acid permeability) relies on the activity of a Ca2+ – Mg2+ requiring ATPase. In addition, cell volume regulation and the amino acid efflux are accompanied by an alteration in the number of membrane associated particles per unit of membrane area. While the relationship between the ATPase activity, membrane associated particles and amino acid permeability is not yet clear, there is good evidence that the mechanism of cell volume control resides with the cell membrane in these animals.
Water compartmentalisation in insects
Authors: Machin John 
Published: June 2005

AbstractTenebrionid beetle larvae survive prolonged dehydration as well as rapid water vapor intake without exchanging solutes with their environments. Tissue water is partially regulated at the expense of the hemolymph. This presumably optimum sharing of water is brought about by the mobilization of osmotically active solutes in hydrated animals and by their storage and osmotic inactivation in dehydrated specimens. The principal solutes involved are amino acids, trehalose, sodium, and chloride.Between moults the rectal complex generates extremely high osmotic pressures (6.7 Osm.kg−1 in Tenebrio) for the purposes of fecal dehydration and water vapor absorption. Rectal osmotic pressures run down to hemolymph levels (about 0.6 Osm.kg−1) at the onset of moulting. Tubule and rectal epithelial cells show remarkably little change in volume over this osmotic range. Volume regulation probably protects the cells from bursting and increases the efficiency of osmotic coupling between rectal lumen and the tubules during water transport. The possibility of using ions from the gut to bring about regulation in epithelial cells is discussed.
Intracranial joint movements in the Agamid lizard Amphibolurus barbatus
Authors: Throckmorton Gaylord S. , Clarke Lewis K. 
Published: June 2005

AbstractMovement at the quadrate‐articular, quadrate‐squamosal, frontoparietal, and basipterygoid joints of the lizard Amphibolurus barbatus were measured from biplanar cinefluorographs taken at 60 fps while the animals were feeding on crickets. Resolution of the cinefluorographs was enhanced by placing tantulum pins into the lizard's skull at selected sites. The X, Y, and Z coordinates of the pins in each film frame were recorded using a computer assisted digitizing tablet. A computer program then calculated for each frame the angular position of the skeletal elements of each of the four joints.The results from 29 chewing cycles show that in Amphibolurus: 1) During the opening and closing phases of most chewing cycles quadrate movement is negatively correlated with movement at the mandibular joint. Thus, as the jaws open, the quadrate rotates anteriorly tending to reduce gape and protracting the lower jaw. 2) Movement of the quadrate is independent of movement at the other intracranial joints. 3) The amount of movement at the frontoparietal joint is inconsistent with Frazzetta's ('62) model of lizard cranial kinesis. 4) In many chewing cycles, the fleshy tongue holds the prey against the upper jaws as the lower jaw is depressed. 5) During the stationary phase the quadrate tends to rotate anteriorly.These results suggest that in Amphibolurus quadrate movement serves two functions: 1) food transport during the opening and closing phases as suggested by Robinson ('66), and 2) during the stationary phase the movement serves to increase mechanical advantage of the pterygoideus muscle as suggested by Smith ('80).
Tyrosinase subcellular distribution and kinetic parameters in wild type and c‐locus mutant C57BL/6J mice
Authors: Townsend Dewayne , Witkop Carl J. , Mattson Judith 
Published: June 2005

AbstractThe distribution and kinetic parameters of tyrosinase (EC 1.14.–18.1) from anagen hair follicles of the C57BL/6J mouse and several c‐locus mutants were investigated. The results showed that c‐locus mutations not only influenced the total tyrosinase activity, but the subcellular distribution as well. The kinetic parameters of tyrosinase were not influenced by the pigment mutations, suggesting that the mutations were not influencing the structure of the enzyme.
Chondrogenesis in the mutant nanomelia. Changes in the fine structure and proteoglycan synthesis in high density limb bud cell cultures
Authors: Sawyer Linwood M. , Goetinck Paul F. 
Published: June 2005

AbstractHigh density limb bud micromass cultures, derived from individual four‐day embryos, were established in order to examine chondrogenesis in normal and nanomelic embryos. One‐ and three‐day cultures revealed no morphological differences between the two genotypes. At six days in culture, the scalloping of the cell surface observed in normal chondrocytes is not extensive in the mutant, and the extracellular matrix granules are greatly reduced in number. Differences in sulfated proteoglycan (PGS) synthesis were first detected at three days in culture when the mutant failed to synthesize cartilage‐specific PGS. The study, therefore, indicates that the mutant gene is not expressed in prechondrogenic cells.
The metamorphosis of the humeral disc of Drosophila melanogaster
Authors: Pedelty Joey , Arking Robert 
Published: June 2005

AbstractThe metamorphosis of the Drosophila humeral (dorsal prothoracic) disc was examined using histological procedures as well as both in vivo and in vitro culture techniques. The histological analysis was done at four developmental stages: late third instar larvae, early pre‐pupae, late pre‐pupae, and early pupae. In the late third instar larva, the disc forms a cylinder around the tracheal tubule just posterior to the anterior spiracles and consists of an outer layer of imaginal cells and an inner layer of larval cells. Evagination of the disc begins in the early prepupal stage and consists of a marked medial and posterior migration of the imaginal cells along each of the lateral tracheal trunks. By the late prepupal stage the disc has come into contact with the evaginating wing disc and has formed two structures, an anterior tubular structure which will form the second thoracic spiracle (SpTh2) and a posterior multilayered spherical structure which will form the single layered humeral callus of the adult. By the early pupal stage the humeral callus has become integrated with the rest of the thorax and the SpTh2 is contiguous with the developing adult tracheal system. In vitro cultures also showed a marked posterior migration of the imaginal cells along the tracheal trunk during the first 20–24 hours of culture which corresponds to the normal evagination period of cultured wing and leg discs. No resulting apolysis or differentiation of the cultured humeral discs was observed. Only a low level of differentiation was obtained following the in vivo culture of humeral discs. In both culture experiments, normal levels of differentiation were exhibited by the control (ventral prothoracic) discs. A hypothesis involving the possible requirement of humeral disc‐wing disc contact as a prerequisite for differentiation is presented.
Collagenase solutions induce in vitro ovulation in lobsters (Homarus americanus)
Authors: Talbot Prudence 
Published: June 2005

AbstractThe effect of several hydrolytic enzymes on ovulation of lobster (Homarus americanus) oocytes was studied in vitro using strips of ovarian tissue. Only ovaries which were judged by candling and microscopic examination to be close to natural ovulation were used. Ovaries were removed and cut into small, flat strips (1 cm2) and placed in either seawater (SW) or SW containing an enzyme. The number of oocytes ovulated from these strips was determined periodically over a 3–6‐hour period. Of the enzymes tested, only crude collagenase treatment produced ovulation. Highly purified collagenase was tested subsequently and found effective. Moreover, when cysteine, a collagenase inhibitor, was added to crude collagenase preparations, ovulation did not occur. These results (1) show that mature lobster ovaries will undergo in vitro ovulation in SW solutions containing collagenase, and (2) are the first demonstration that a hydrolytic enzyme may be directly involved in invertebrate ovulation. It is suggested that collagenase disrupts the thick basement membrane surrounding each follicle, thus initiating follicular rupture and subsequent extrusion of the oocyte. This technique provides a useful method for in vitro studies of lobster ovulation.
Effects of 18 weeks of daily melatonin injection on reproduction and temperature regulation in the mouse, Peromyscus leucopus
Authors: Heath Harley W. , Lynch G. Robert 
Published: June 2005

AbstractMice injected daily with 50 μg of melatonin, 12 hr after lights on, for 18 weeks, underwent gonadal regression after 4–7 weeks and reproductive recrudescence after 15 weeks. Most treated animals molted to a winter pelt after 9–11 weeks of injections, and 2 of the 10 mice experienced bouts of daily torpor after 14 weeks.
Deoxycorticosterone‐induced precocious hatching of teleost embryos
Authors: Cloud J. G. 
Published: June 2005

AbstractEmbryos of the teleost (Oryzias latipes) incubated at 22–23°C in medium containing deoxycorticosterone (DOC) at a concentration of 1μg/ml hatched in 11.7 days; embryos incubated under identical conditions in rearing medium alone or in rearing medium plus the steroid vehicle hatched in 22.3 and 22.2 days, respectively. The rate of development of embryos incubated with DOC was not different from that of control. Addition of DOC to the rearing medium at either 0, 4, or 8 days after fertilization resulted in a reduction of hatching time relative to the control group, but there was no significant difference in the time of hatching between these DOC‐treated groups. Increasing the rate of embryogenesis by increasing incubation temperature to 28°C resulted in a decrease in hatching time in both DOC‐treated and control embryos. The time required for hatching decreased in a dose‐dependent manner as the concentration of DOC in the incubation media increased from 0 to 1 μg/ml. Since hatching of teleost embryos is dependent upon enzymatic solubilization of the chorion, these data suggest that exogenous deoxycorticosteron induces the precocious release of hatching enzymes from the teleostean larvae.
Histochemical study of the amphibian digestive tract during normal and thyroxine‐induced metamorphosis. II. Acid phosphatase
Authors: Kaltenbach Jane C. , Wang Claire H. K. , Lipson Marcia J. 
Published: June 2005

AbstractThis histochemical study comprises a comprehensive overview of acid phosphatase distribution along the entire length of the digestive tract from esophagus through large intestine of growing and metamorphosing larvae and mature frogs of a single anuran species, Rana pipiens. The main site of enzyme localization throughout the length of the tube is the supranuclear area of the mucosal epithelium. However, activity of the enzyme varies markedly, not only in different locations (e.g., weak in the esophagus, strong in the small intestine), but also in different stages of larval development. During limb bud—early metamorphic stages (I—XX), activity is localized only in epithelial cells (supranuclear zone and scattered basal foci) and in glands of the stomach. Activity in these sites increases when remodeling of the digestive tract begins in the latter stages of this period. By mid‐metamorphosis (XXI—XXII), shortening of the tract has become maximal, and acid phosphatase‐positive epithelial cells have degenerated and sloughed into the lumen. In contrast, enzyme activity appears (albeit transitorily) in a new location, namely, in connective tissue thickening along the length of the tract. A similar histochemical picture can be induced precociously by thyroxine treatment. By the end of metamorphosis (XXIII—XXV), activity again appears in mucosal epithelium, but in newly differentiated adult‐type cells as well as in gastric and initially‐forming esophageal glands (the only two types of multicellular glands in the digestive tract). In adult frogs, activity remains in these sites and in scattered points (probably phagocytes) in the connective tissue; however, activity is generally weaker than in early‐stage larvae.
Developmental changes in acid proteases of the avian proventriculus
Authors: Yasugi Sadao , Mizuno Takeo 
Published: June 2005

AbstractDevelopmental changes in acid proteases in the chicken and quail proventriculus were studied. During embryonic stages, the specific acid protease activity of both species showed a peak a few days before hatching and decreased towards the end of the incubation period. The electrophoretic patterns of acid proteases changed considerably at these stages. Within 24 hr after hatching, the activity increased about 30 times that of embryonic stages. Concomitant with this rapid increase, was a shift of electrophoretic patterns to the adult type. This shift occurred even in nonfed, hatched fowls. Electrophoretic patterns and immunochemical studies with the purified chicken and quail pepsinogens revealed that the embryonic and adult proventriculi of both species have stage‐specific and species‐specific pepsinogens.
Anaerobic metabolism in freely diving painted turtles (Chrysemys picta)
Authors: Gatten Robert E. 
Published: June 2005

AbstractThe degree to which painted turtles (Chrysemys picta) rely on anaerobic metabolism during unrestrained, voluntary dives was estimated by measuring the total body lactate content of turtles in the lab and in outdoor pools in summer and in winter. Experiments with forcibly submerged animals were carried out for comparative purposes. Summer turtles diving voluntarily in an aquarium at 25°C during a 5‐day experiment did not accumulate lactate (x̄ = 20 mg%). When turtles in water at 25°C were threatened and prodded but not restrained or forcibly immersed, their total body lactate content increased fourfold in 60 min. Animals forcibly submerged for 2 days at 25°C exhibited total body lactate levels up to 300 mg%. Summer turtles diving undisturbed in outdoor pools had lactate levels which were low (x̄ = 10 mg%) and which were correlated with water temperature, but not with time of day, intensity of activity in the hour prior to sampling, or the time interval since the last breath. Winter turtles forcibly submerged in an aquarium at 5°C did not exhibit a total body lactate level of 300 mg% until 2 weeks had elapsed. Winter animals diving undisturbed in an outdoor tank had lactate levels (up to 558 mg%) unrelated to time of day, water temperature (x̄ = 3.7°C), or ice thickness, but highly correlated with the duration of their hibernation (up to 67 days). These results are consistent with the hypothesis that painted turtles in nature rely on anaerobiosis when forced by a predator to remain submerged and during hibernation but not during routine diving at moderate temperatures.