bluuebunny/crossref_metadata_2025_split huggingface dataset:
Placentation
Authors: Benirschke Kurt 
Published: June 2005

AbstractPlacental development differs greatly among members of different taxa. Not only does blastocyst attachment take place at different times, the penetration of trophoblast varies considerably. From an epitheliochorial relationship between fetus and mother to the hemochorial placentation of taxa, such as the higher primates, the trophoblast becomes increasingly exposed to maternal immune recognition which may be one cause of rejection in interspecific embryo transfers or hybridization. Shape of uterus and endometrium and genetic factors govern the morphologic form of the placenta. The paper reviews ungulate placentation, successes and failures of interspecific embryo transfers, and the scant knowledge of genetic determinants in primate placentas.
Energy metabolism of arthropods and mollusks during environmental and functional anaerobiosis
Authors: Gäde Gerd 
Published: June 2005

AbstractDuring environmental anaerobiosis, when the whole organism is exposed to anoxic conditions caused by external, physical factors in the microhabitat, arginine phosphate, glycogen, and aspartate (only mollusks) are the substrates for the metabolism. Main end products formed are lactate (Crustacea, Xiphosura, some Gastropoda and Bivalvia), alanine, succinate, and the volatile fatty acids, propionate and acetate (most Gastropoda and most Bivalvia). Because of reduction of the overall metabolism in bivalves, utilization and production rates of substrates and end products, respectively, are low. They are generally faster in Crustacea, which do not reduce their metabolism.During functional anaerobiosis, when the muscle tissue becomes anoxic because of increased work done by the animal, energy is derived from arginine phosphate and glycogen. The main end products formed are lactate (Crustacea), octopine (active Gastropoda and Bivalvia), and strombine/alanopine (some gastropod species). Utilization rates of the phosphagen and production rate of lactate and opines are sometimes more than 500‐fold higher than during environmental anaerobiosis. These strong variations in the glycolytic flux are probably regulated by the influence of the phosphagen and adenylates on regulatory enzymes and by the NADH/NAD ratio.
Cell multiplication and blastoderm development in relation to egg envelope formation during uterine development of quail (Coturnix coturnix japonica) embryo
Authors: Stepińska Urszula , Olszańska Bozenna 
Published: June 2005

AbstractThe relationship between the number of cells and blastoderm development to the formation of the egg envelopes is established for the uterine period of quail embryogenesis. On the basis of this relationship, the developmental stage of the embryo can be estimated without destroying the egg or dissecting the embryo. Data are also presented on the number of cells in the quail embryo at the time of egg laying and during the first hours of incubation. These data are critically compared to those in other reports dealing with quail and chick embryos.
Identification of an hemipteran juvenile hormone: In vitro biosynthesis of JH III by Dysdercus fasciatus
Authors: Bowers W. S. , Marsella P. A. , Evans P. H. 
Published: June 2005

AbstractCorpora allata of the African cotton stainer, Dysdercus fasciatus Sign. (Hemiptera: Pyrrhocoridae), produce radiolabeled methyl‐10,11‐epoxy‐3,7,11‐trimethyldodeca‐2E,6E‐dienoate (JH III) when cultured in a medium containing L‐[methyl‐14C] methionine. Similar in vitro studies show JH III biosynthesis by cultured corpora allata of Lygaeid and Pentatomid species. This is the first identification of a juvenile hormone in Hemiptera.
Cellular aspects of alloimmune reactions in sponges of the genus Axinella II. Axinella verrucosa and Axinella damicornis
Authors: Buscema Marco , Van de Vyver Gysèle 
Published: June 2005

AbstractThe analysis and understanding of immune reactions in sponges are presently impaired by numerous discrepancies and inconsistencies between the results obtained for different species that make critical judgment difficult. In order to determine the possible influence of experimental procedures, parabiotic allografts were performed on Axinella verrucosa and Axinella damicornis. Three reactions were observed in allogrfts of Axinella verrucosa: acceptance, nonfusion, and chronic rejection. The acceptance reaction differed from the fusion of control autografts by a transient phase of dense cell accumulation between the parabionts. Nonfusion resulted in the virtual absence of reaction between the incompatible sponges. Chronic rejection was characterized by: 1) intensive cell migration and accumulation of collencytes in the zone of contact; 2) regular alignment of these cells on each side of that zone; 3) deposition of a collagen barrier that progressively joined but demarcated the parabionts. Some sponges presented nonfusion or chronic rejection depending on their graft partner. All allografts in Axinella damicornis displayed a chronic rejection reaction, which was essentially similar, but more intense and faster, than in Axinella verrucosa. However, in Axinella damicornis, the parabionts which were separated by the barrier became independent instead of joined. Reasons for and the implications of such a diversity of immune reactions in sponges are discussed.
Neural crest cell behavior in white and dark larvae of Ambystoma mexicanum: Differences in cell morphology, arrangement, and extracellular matrix as related to migration
Authors: Spieth J. , Keller R. E. 
Published: June 2005

AbstractMelanocytes of white (d/d) larvae of the Mexican axolotl (Ambystoma mexicanum) are confined to the dorsal midline of the trunk region, whereas in dark (D/‐) larvae they are spread laterally on the flank as well, where they contribute to the normal pigment pattern of the trunk. Pigment cell migration in the subepidermal space of white larvae is inhibited by the white epidermis (Dalton '50; Keller et al., '82). The present scanning electron microscopic study describes a well‐defined sequence of changes in shape and arrangement of neural crest cells during and after their segregation from the neural tube in both dark and white axolotls. The morphology of the neural crest cells migrating in the subepidermal pathway of dark larvae is correlated with their motile behavior and pattern of migration in vivo, as described by time‐lapse cinemicrography (Keller and Spieth, '83). Also, the structures of the matrix material in the subepidermal space of dark and white axolotls differ in ways that may be related to the epidermal inhibition of migration in the latter. Numerous possibilities for contact guidance offered by the structure and topography of the substrata, neighboring cells, and the extracellular matrix in the migration path are described and discussed.
Contraction of an embryonic epithelium, the enveloping layer of the medaka (Oryzias latipes), a teleost
Authors: Fluck R. A. , Killian C. E. , Miller K. , Dalpe J. N. , Shih T.‐M. 
Published: June 2005

AbstractThe enveloping layer (EVL), a simple epithelium that forms the outer covering of the blastoderm of the teleost embryo, contracted in situ when it was exposed to the calcium ionophore A23187. This contraction was inhibited by cytochalasin D and occurred in a Ca2+‐free medium. When the EVL was detached from the rest of the embryo, it contracted into a tight ball. Detached EVLs contracted fully in Na+‐, K+‐, SO4−2−, Mg2+‐, or glucose‐free medium but only partially in medium containing less than 10 μM free Ca2+ Contraction was inhibited by the polyvalent cations La3+, Ni2+, Co2+, and Mn2+ but not by the “calcium antagonists” D 600, verapamil, nifedipine, or papaverine; it was only slightly inhibited by the “calcium antagonist” diltiazem. The contraction was inhibited by cytochalasin B (1 μg/ml) and cytochalasin D (1 μg/ml) but not by demecolcine (0.35 mM) or colchicine (1 mM). The effects of lowered free Ca2+ and the cytochalasins were reversible.The contraction of EVLs permeabilized by the detergent Brij 58 was ATP and Ca2+ dependent. In the presence of 5 mM MgATP, the EVLs contracted only when the medium contained at least 1 μM free Ca2+. Three other nucleotides—ITP, GTP, and CTP—also supported contraction but at a lower rate than ATP. The contraction of permeabilized EVLs was inhibited by cytochalasin B (1 μg/ml), N‐ethylmaleimide (6 mM), but not by 10 μM vanadate.Dissociated cells of the EVL underwent circus movement, which was inhibited nearly completely by cytochalasin B, cytochalasin D, and La3+ and inhibited partially by Ni2+, Mn2+, and Co2+. Although the EVLs contain acetylcholine (1.2 pmol/EVL), the amount did not change significantly during contraction. The cholinergic antagonists d‐tubocurarine and atropine sulfate and the cholinergic agonist carbamylcholine had no effect on the contraction.We conclude that the contraction of detached EVLs is an ATP‐, Ca2+‐dependent phenomenon and that part of the Ca2+ required for contraction enters the cytoplasm from the medium. Microtubules have no apparent role in the contraction, but microfilaments probably do. Acetylcholine apparently has no role in the contraction.
The influence of flank dermis on limb regeneration in the newt, Notophthalmus viridescens
Authors: Tank Patrick W. 
Published: June 2005

AbstractThe ability of nonlimb skin to support forelimb regeneration was studied in the newt, Notophthalmus viridescens. When forelimb skin was replaced by skin removed from the flank followed by amputation through the graft, 96% of the limbs did not regenerate. Varying the orientation of the skin graft around the limb did not affect this outcome. When limb stumps were covered by flank epidermis independent of flank dermis, normal forelimb structures regenerated (86%). When flank dermis was grafted to the limb independent of flank epidermis, 66% of experimental limbs did not regenerate. When flank skin was grafted proximal to the regenerate at several times after amputation (3, 9, or 15 days), 72% of the experimental limbs did not regenerate. Finally, limb stumps that contained no dermis at the level of amputation underwent normal regeneration (86%). These results indicate that flank skin does not support forelimb regeneration in the newt. The dermal component of flank skin is responsible for this outcome.
Forelimbs of the newt Notophthalmus viridescens continuously denervated for up to six weeks prior to amputation do not regenerate
Authors: Scadding Steven R. 
Published: June 2005

AbstractIt has been suggested that urodele forelimbs become “addicted” to innervation, because they will not regenerate in the absence of nerves. Recently, evidence has been provided that indicates that if axolotl forelimbs are denervated for 3 or 4 wk prior to amputation, they will regenerate in the absence or near absence of nerves since the addiction is broken and regeneration can occur (Wallace, '81). The present investigation was designed to determine if forelimbs of the newt Notophthalmus viridescens could regenerate in the absence of nerves when the forelimbs were maintained in a denervated state for several weeks prior to amputation. Thus, newts had their forelimbs denervated by transection of the brachial plexus at intervals of 0, 2, 4, 6 wk prior to forelimb amputation through the radius and ulna. Denervations were repeated at 2‐wk intervals to prevent regrowth of the nerves. After amputation, the limbs were observed and the degree of regeneration observed. The results indicated that regardless of the length of the prior denervation period, denervated limbs consistently failed to regenerate. In the newt, it appears that long‐term denervation does not significantly modify the requirement for nerves during forelimb regeneration.
Renal handling of phosphate, calcium, sodium, and potassium in intact and parathyroidectomized Rana pipiens
Authors: Sasayama Yuichi , Clark Nancy B. 
Published: June 2005

AbstractRenal excretion of phosphate, calcium, sodium, and potassium in intact and parathyroidectomized male Rana pipiens was studied by renal clearance techniques using 14C‐inulin. In intact frogs, 57% of filtered phosphate, 60% of filtered calcium, 97% of filtered sodium, and 89% of filtered potassium was reabsorbed by the renal tubules. Following parathyroidectomy, the rate of reabsorption of phosphate became significantly higher than that of the intact frog, and the relative phosphate clearance (fractional excretion) decreased. These changes corresponded with a gradual rise in serum phosphate values. There was no major effect on excretion patterns of calcium, sodium, or potassium after parathyroidectomy. These results suggest that in frogs the parathyroid glands strongly influence phosphate excretion patterns but have little effect on the excretion of calcium, sodium, or potassium.
Separation and labeling of specific subpopulations of Botryllus blood cells
Authors: Schlumpberger Jay M. , Weissman Irving L. , Scofield Virginia L. 
Published: June 2005

AbstractBlood cells of the colonial tunicate Botryllus were separated by density gradient centrifugation in Percoll. Unseparated blood cells were used to immunize mice for development of hybridoma cell lines producing anti‐Botryllus monoclonal antibodies. These antibodies identify specific subpopulations of blood cells, indicating possible divisions of these cells into defined subgroups sharing particular differentiation antigens. Additional studies utilizing fluorescein‐conjugated lectins also revealed differential binding to density‐ and monoclonal antibody‐defined blood cell fractions. These methods allow separation of the different Botryllus blood cell types for functional studies.
Electron microscopic studies of planarian regeneration. IV. Cell division of neoblasts in Dugesia dorotocephala
Authors: Morita Michio , Best Jay Boyd 
Published: June 2005

AbstractThere has been disagreement regarding the source of new cells for planarian regeneration. Electron microscopy was used to study this problem in surgically decapitated asexual Dugesia dorotocephala. Comparison of the fine structural morphology of cells found in prophase, metaphase, anaphase, and telophase with those of various cell types in interphase shows that the mitotic cells and resulting daughter cells are all neoblasts. This mitosis, which appears quite classical, was observed in the parenchyma of preexisting tissue but not in the regeneration blastema. This accords with previous observations indicating that blastema cells are already differentiated out of the neoblast stage, and the present observation that mitotic activity appears restricted to neoblasts. However, persistence of neoblast characteristics, e.g., numerous free, or poly‐, ribosomes and diminished, but still prominent, nuclear satellite material, indicate recent differentiation of blastema cells from neoblasts. Previous studies have shown a basal mitotic rate in the parenchymal neoblasts of uninjured asexual planarians. This mitotic incidence remains the same for the first day, then increases to a maximum on the second and third days following decapitation. Despite an exhaustive search involving construction of electronmicrographic montages of all or most of the wound area and adjacent tissue at various times ranging from 1 to 72 hours after decapitation, no evidence of cellular dedifferentiation was observed. Joint consideration of present and previous results indicate that new specialized cells, whether required for normal turnover replacement, asexual reproduction, or reconstitutive regeneration, are all differentiated from parenchymal neoblasts which maintain their numbers by mitotic production of more neoblasts.
Changes in protein phosphorylation during the maturation of mammalian oocytes in vitro
Authors: Crosby Ian M. , Osborn Jeremy C. , Moor Robert M. 
Published: June 2005

AbstractCumulus‐enclosed sheep oocytes were cultured in gonadotrophin‐containing medium for up to 9 hr and were then incubated for 3 hr in the presence of [32P]phosphate. The incorporation of 32P into TCA‐insoluble material was measured, and oocyte proteins were separated by one‐ and two‐ dimensional gel electrophoresis.Incorporation of [32P]phosphate into protein increased after 3 hr of culture and again after 9 hr, the time of germinal vesicle breakdown (GVBD). Qualitative and quantitative changes in the phosphorylation of proteins occurred over the 12‐hr period studied. One of the most prominent changes was the appearance of a band of Mr 33,000, which was absent at 0–3 hr but appeared with increasing intensity with longer periods of culture. Two‐dimensional electrophoresis revealed that the bulk of material in this band was a neutral polypeptide. No significant incorporation of [32P]phosphate was found in ribosomal extracts of oocytes.
An improved method for destroying mouse blastomeres electrically inside the zona pellucida and the in vitro development of the surviving blastomeres
Authors: Tojo Hideaki , Ogita Zen‐Ichi 
Published: June 2005

AbstractAn improved method for isolating mouse blastomeres by electrically destroying the other blastomeres inside the zona pellucida is described. Instruments required are two micromanipulators connected to an inverted microscope and an electronic stimulator equipped with an isolator. The target blastomere in which a glass microelectrode is inserted disintegrates completely within a few seconds after a direct current is applied. Complete destruction of a blastomere requires more than 60 μA delivered at 8 V. Destruction of blastomeres occurred mainly as a result of the medium penetrating the blastomere due to the change of membrane potential in both the zona and the blastomere. Most one‐half, two‐quarter, and three‐quarter embryos obtained in this way developed in vitro into normal blastocysts (76.4–86.2%). By contrast, there was a marked decrease (35.3%) of developmental potential in one‐quarter embryos. The results indicate that the present method is an improvement over previous methods of obtaining mammalian blastomeres inside the zona pellucida.
A daily rhythm in heat tolerance in the salt marsh fish Fundulus heteroclitus
Authors: Bulger Arthur J. 
Published: June 2005

Abstract1)A daily rhythm in heat tolerance occurs in Fundulus heteroclitus acclimated to temperatures of 12°C or 27°C; the rhythm persists at least 30 days in the laboratory in the absence of any thermal fluctuation. 2) The significance of the rhythm appears to be anticipation of daily temperature changes in a highly fluctuating thermal environment. 3) A normal photoperiod is necessary for the full expression of the rhythm, although it appears to have a weak endogenous component which persists in darkness.
Pressure inhibition of starfish oocyte maturation: Temporal aspects
Authors: Cloud J. G. 
Published: June 2005

AbstractHigh hydrostatic pressure reversibly inhibits 1‐methylade‐nine (1‐MA)‐induced maturation of starfish oocytes; the objective of this investigation was to describe more fully the nature of this inhibition. Oocytes incubated at atmospheric pressure following a 90‐min period with 1‐MA at high pressure and the removal of exogenous 1‐MA immediately after the reduction in pressure failed to mature. Furthermore, the time required for germinal vesicle breakdown at atmospheric pressure in oocytes preincubated with 1‐MA for 15 min at high pressure was not less than the time required for untreated control oocytes. From a comparison of the percentage of oocytes that matured when incubated at atmospheric or elevated pressure with or without ammonium (20 mM), an inhibitor of 1‐MA that appears to act during an initial step of the hormone dependent period, it was found that the inhibitory action of pressure and ammonium was additive. Inhibition of oocyte maturation was reversible even after 20 hr of incubation at high pressure, but the percentage of oocytes that matured when subsequently incubated at atmospheric pressure was reduced in those oocytes incubated at the elevated pressure with 1‐MA. Taken together, these results suggest that high pressure, like ammonium, inhibits an initial step in the maturational process and that oocytes incubated with 1‐MA at high pressure have a reduced responsiveness to 1‐MA when subsequently incubated at atmospheric pressure.
Further evidence that formation of the neural tube requires elongation of the nervous system
Authors: Jacobson Antone G. 
Published: June 2005

AbstractIn previous papers, we have correlated rapid elongation of the midline of the neural plate with the time of closure of the plate into a tube in the newt embryo and at one stage of the chick embryo. We proposed a model in which stretching of the midline of the plate causes the plate to buckle out of the plane and roll into a tube. In this paper, I show for another stage of development in the chick embryo, the period of closure of the brain tube, that rapid elongation of the nervous system accompanies closure of the tube. If elongation of the brain plate causes formation of the tube, then treatments that stop tube formation should also stop brain elongation. I tested this hypothesis by using low fluences of UV irradiation, known to stop tube formation (Davis, '44), and measuring the effects on elongation of the brain plate. The open plates of UV‐irradiated embryos failed to elongate normally. Furthermore, photoreactivation with longer wavelengths of light reversed the UV effects and allowed closure of the tube in UV‐irradiated embryos. These embryos elongated their brains.
An analysis of Sciara ocellaris gynandromorphs and the morphogenetic fate map of presumptive adult cuticular structures
Authors: Mori Lyria , Perondini André L. P. 
Published: June 2005

AbstractGynandromorphs have been collected in different crosses of Sciara ocellaris involving the mutation sepia. Gynandromorphs develop only from heterozygous zygotes. The mean proportion of male tissue in these gynandromorphs is variable and related to the genotype of the parental females, and is higher when the cytoplasm of the egg is under the influence of sepia. The results give support for the hypothesis of the existence of a cytoplasmic component involved in the process of X‐chromosome elimination in the embryo of sciarid flies. The distribution of phenotypes in the adult gynandromorphs is nonrandom. The frequency with which each of the 27 cuticular structures is XO is higher for the anterior parts of the body and decreases toward the posterior. A morphogenetic fate map placing the origin of these cuticular structures on the blastoderm surface was constructed. The map agrees in its general features and in the calculated mapping function with those previously made for other insects.
Hormonal regulation of the annual pelage color cycle in the Djungarian hamster, Phodopus sungorus. I. Role of the gonads and the pituitary
Authors: Duncan Marilyn J. , Goldman Bruce D. 
Published: June 2005

AbstractThe Djungarian hamster exhibits an agouti pelage in the summer and a predominantly white pelage in the winter. This pelage color cycle is known to be regulated by the length of the daily photoperiod probably acting through the pineal gland, as is the seasonal cycle of reproductive function with which it is closely correlated (Figala et al., '73; Hoffmann, '78b). The possibility of a causal relationship between the decline in gonadal hormone secretion and the coat color change occurring in short photoperiod was examined. Gonadectomized and intact male and female hamsters were exposed to either long (16L:8D) or short (10L:14D) photoperiod for several months. Gonadectomy neither induced the change to the winter pelage color in long photoperiod‐housed animals, nor prevented either the change to the winter pelage or the spontaneous return to summer pelage color in short photoperiod‐housed animals. Chronic implants of testosterone in castrated males delayed and attenuated the short photoperiod‐induced coat color change. Administration of ovine prolactin (100 μg/day) stimulated pigmentation in hamsters with the winter pelage, whereas administration of a αMSH (30 μg/ day) was without effect. These results suggest that changes in pelage color may be regulated largely by changes in pituitary prolactin secretion and modified to some extent by changes in gonadal steroid hormone secretion.