bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uterogestation and placentation in elasmobranchs
Authors: Hamlett William C. , Eulitt Allison M. , Jarrell Robert L. , Kelly Matthew A. 
Published: June 2005

AbstractElasmobranch fishes utilize a variety of means to provide nourishment for their developing young. All employ internal fertilization and sperm storage within the female genital tract. Some elasmobranchs, including all the skates and some sharks, are oviparous. In these species, fertilized eggs are enclosed in a tough egg case that is secreted by the nidamental or shell gland. The female lays the egg cases and development is entirely dependent on the yolk stores sequestered in the yolk sac. Upon oviposition, the embryo weighs less than the fertilized egg. The majority of elasmobranchs are viviparous, however, and utilize a variety of strategies to provide nourishment and satisfy respiratory demands of the developing young. Some sharks simply retain their young in the dilated posterior segment of the oviduct. In its simplest form, the maternal uterus does not provide any additional nutrients to the embryos. Other elasmobranchs develop secretory uterine villi that produce nutrient histotroph to supplement oocyte yolk stores. Uterine secretions find their zenith in the stingrays. Following yolk depletion, the uterine lining hypertrophies into secretory appendages termed trophonemata. The process by which the uterine secretions, also known as uterine milk or histotroph, are elaborated resembles the production of breast milk in higher vertebrates, and the milk is rich in protein and lipid. Concurrent with growth of the embryos, the vascular bed of the trophonemata enlarges to form sinusoids that project out to the surface to form a functional respiratory membrane. In lamnoid sharks, following yolk use, the embryos develop precocious dentition and feed on intrauterine eggs and siblings. There is generally one fetus per uterus and it grows to enormous proportions of up to 4 feet in length. In placental sharks the yolk sac is not withdrawn to become incorporated into the abdominal wall. Instead, it lengthens to form an umbilical cord and the yolk sac becomes modified into a functional epitheliochorial placenta. © 1993 Wiley‐Liss, Inc.
Maternal–embryonic relations in viviparous teleosts
Authors: Schindler Joachim F. , Hamlett William C. 
Published: June 2005

AbstractTeleosts do not possess uteri and ovulation occurs into the ovarian lumen. Hence, osteichthyan viviparity is characterized by intrafollicular gestation or intraluminal gestation (within the ovarian cavity), and thus, the ovary functions both in egg production and maintenance of the developing embryos. Because there is no attachment between embryonic and maternal tissues, maternal‐embryonic exchange of gas, electrolytes, nutrients, metabolic waste, and possibly effector molecules and immunoglobulins is mediated by embryotrophe. In several instances it has been demonstrated that embryotrophic proteins originate from maternal serum rather than from elaboration within ovarian tissues. In intraluminal gestation, the ovarian wall becomes hypervascularized and the inner ovarian epithelium lining the ovarian cavity secretes embryotrophe. Trophotaeniae provide extraembryonic endodermal exchange surfaces in many species undergoing intraluminal gestation. There is a strong indication of a trophotaenial membrane binding system for proteins containing appreciable amounts of lysine. In intrafollicular gestation, yolk, pericardial and coelomic sacs play a major role in physiologic exchange. In most instances, intrafollicular gestation is associated with extraembryonic fine structural modifications consistent with respiratory and osmoregulatory functions. The postulated role in nutrient transfer requires experimental evidence. In matrotrophic viviparous teleosts, the gut may provide an effective absorptive surface. On the other hand, the skin, and perhaps the gills and buccopharyngeal tissue, serve as respiratory surfaces. As yet, no experimental evidence suggests exchange of metabolites at these sites. © 1993 Wiley‐Liss, Inc.
Uses and limitations of mammalian fetal membranes and placenta for phylogenetic reconstruction
Authors: Luckett W. Patrick 
Published: June 2005

AbstractComparative studies on the development of the mammalian fetal membranes and placenta, and discussions of the possible evolutionary significance of these data, have been carried out for more than a century. Throughout much of this period, however, such data were considered in isolation from cranioskeletal and other biological findings, so that only rarely were placental features incorporated into comparative assessments of mammalian evolution. Evolutionary interpretations of the fetal membrane evidence were commonly based on the concept of overall similarity, and most placentologists were strongly influenced by the widely accepted hypothesis that living “insectivores” were closely related to the ancestral eutherian mammals.Mossman's emphasis on the use of all available developmental data on the fetal membranes and placenta, rather than simply the nature of the definitive placenta, marked a turning point in the history of using such findings for assessing eutherian mammalian evolution. Recent advances in the methodology of phylogenetic inference, with emphasis on evaluating convergence versus homology, and on distinguishing between relatively primitive versus derived homologous similarities shared by two or more taxa, have provided a sound framework for the phylogenetic analysis of fetal membrane data. Character analysis of mammalian fetal membrane traits provides a mechanism for testing phylogenetic hypotheses formulated by cranioskeletal features. It is emphasized in this study that fetal membrane data have their greatest input into assessing mammalian phylogeny when they are evaluated in conjunction with the available cranioskeletal and molecular evidence. © 1993 Wiley‐Liss, Inc.
Development and characteristics of placentation in a carnivore, the domestic cat
Authors: Leiser Rudolf , Koob Bärbel 
Published: June 2005

AbstractAmong the carnivores, development of the fetal membranes and placentation have now been particularly well studied in the domestic cat (Felis catus). Initially, the cat conceptus is bordered by a primitive and a precontact chorion. This becomes part of a temporary choriovitelline placenta which is subsequently supplanted by a chorioallantoic placenta. Following thiphasic process of implantation (which involves apposition, adhesion, and intrusion), the chorioallantoic placenta forms a zonary girdle which separates two paraplacental cupules. These cupules are subdivided from base to tips into 1) extravasate zones with hematomal areas and solid junctional areas containing intermingled fetal and maternal tissue, 2) free polar zones with almost no feto‐maternal contact, and 3) interplacental polar zones freely projecting into the uterine lumen or, near the end of pregnancy, facing comparable regions of neighboring fetuses.The placental girdle consists of a lamellar zone characterized by elongate, parallel fetal (chorionic) and maternal (septal) lamellae, a junctional zone where fetal and maternal tissues face each other and intimately intermingle, and a zone of pure endometrial glands. In the lamellar zone the interhemal membrane (placental barrier) is of the endotheliochorial type. As pregnancy progresses, cytotrophoblast in the interhemal barrier contributes to the formation of syncytiotrophoblast and is gradually reduced from being a continuous layer to only scattered cells. The syncytiotrophoblast is usually separated from endothelial cells of the maternal capillaries by a thickened basal lamina (the interstitial membrane) or faces persisting endometrial connective tissue containing some enlarged decidual cells.The efficiency of maternal‐fetal physiological exchange depends not only upon the thickness of the interhemal membrane, which in reduced in places to 1.5 μm, but also upon the materno‐fetal blood flow interrelationship. This is of the simple crosscurrent type in the cat. © 1993 Wiley‐Liss, Inc.
A comparative study on the fusogenic nature of echinoderm and nonechinoderm phagocytes in vitro
Authors: Dan‐Sohkawa Marina , Suzuki Junko , Towa Shuichi , Kaneko Hiroyuki 
Published: June 2005

AbstractPhagocytes obtained from six echinoderm and four nonechinoderm species are compared in culture with respect to their ability to form syncytium. It is shown that phagocytes of all echinoderm species examined form an extensive syncytium while those of three nonechinoderm species shoe no such activity. Phagocytes of an ascidia, on the other hand, formed a less extensive type of syncytium known as a multinucleate giant cell. Kinetic analyses of the process of fusion were performed. Phagocytes of the asteroid, Asterina pectinifera, fuse more readily when transferred to culture condition in an aggregated state than as single cells. The extraordinarily fusogenic nature of echinoderm phagocyte is discussed in relation to the calcareous body wall structure of the echinoderms. © 1993 Wiley‐Liss, Inc.
Specific phosphorylation of membrane proteins of Mr 44, 000 and Mr 32,000 by the autophosphorylated insulin receptor from the hepatopancreas of the Shrimp Penaeus monodon (Crustacea: Decapoda)
Authors: Lin Chung‐Liang , Wang Pei‐Chen , Chuang Nin‐Nin 
Published: June 2005

AbstractThe insulin receptor, purified from the hepatopancreas of the shrimp Penaeus monodon, is a hydrophobic heterodimer of subunits with relative masses (Mr) of 70,000 and 58, 000, as estimated by FPLC on Superose™12 and SDS‐PAGE. Only the subunit of Mr 70,000 was autophosphorylated after the addition of insulin. The autophosphorylation occurred specifically at Tyr residues, as demonstrated by the specific subsequent dephosphorylation by the phosphotyrosyl protein phosphatase from the hepatopancreas of the shrimp Penaeus monodon. Proteins of Mr 44,000 and Mr 32,000 on the plasma membrane from the hepatopancreas of the shrimp Panaeus monodon were phosphorylated by the autophosphorylated insulin receptor from the shrimp hepatopancreas, but not by that from the human placenta. The detergent, Triton X‐100, caused noticeable enhancement of the autophosphorylation of both shrimp and human insulin receptors. © 1993 Wiley‐Liss, Inc.
Consequences of splenectomy on the compensatory mechanism of cutaneous respiration in the newt
Authors: Frangioni Giuliano , Borgioli Gianfranco 
Published: June 2005

AbstractThe spleen of the newt Triturus cristatus carnifex (Laurenti) hoards erythrocytes when the animal is well oxygenated and releases these into circulation when the animal becomes hypoxic. This mechanism allows the newts, amphibians with prevalently cutaneous respiration, to adapt to both environmental and metabolic changes.Splenectomized specimens were anesthetized with chlorbutol (to eliminate movement and lung respiration) and observed in five different conditions: at 18°C in humid air, stirred water, and still water, and at 6°C and 33°C in humid air. The study demonstrates that the newt does not have substitute sites for erythrocyte accumulation. However, though the spleenless specimens are incapable of controlling their cutaneous oxygen supply, they can regulate their blood volume, which diminishes with decreasing temperature causing marked variations in the erythrocyte concentration and hematocrit value.The splenectomized specimens, raised for over a year at 18°C, present typically steatosic livers, with lipid droplets and extremely low hepatocyte glycogen levels, indicating a state of chronic hypoxia due to the prevalently aquatic habits of the newt. In fact, the spleenless newts have significantly fewer erythrocytes (P < 0.001) than the unoperated animals‐‐a total volume of 2.27 ± 0.46 ml per 100 g of body weight compared to 2.74 ± 0.29 (mean ± standard deviation). The limited quantity of erythrocytes can provide adequate oxygen only at low temperatures and in an airy environment or in moving water, while an immobile animal in still water undergoes hypoxia due to the formation around it of an hypoxic =diffusion boundary layer= caused by the low coefficient of oxygen diffusion in water. © 1993 Wiley‐Liss, Inc.
Gonadotropin‐releasing hormone (GnRH) binding characteristics in the testis of goldfish (Carassius auratus)
Authors: Pati Debananda , Habibi Hamid R. 
Published: June 2005

AbstractGonadotropin‐releasing hormone (GnRH) binding sites were characterized in the goldfish testis using an analog of salmon GnRH ([D‐Arg6, Trp7, Leu8, Pro9‐NEt]‐GnRH; sGnRH‐A) as a labeled ligand. Binding of sGnRH‐A to goldfish testicular membrane homogenate was found to be saturable, reversible, and dependent on time, temperature, and tissue concentration. Addition of unlabeled sGnRH‐A displaced the bound 125 I‐sGnRH‐A in a dose‐related manner. Hill plot as well as Scatchard analysis indicated the presence of two classes of binding sites, a high affinity/low capacity site and a low affinity/high capacity site in the goldfish testis. Bound 125I‐sGnRH‐A was also found to be displaceable by sGnRH ([Trp7, Leu8]‐GnRH) and cGnRH‐II ([His5, Trp7, Tyr8,]‐GnRH) which occur naturally in the goldfish brain. sGnRH‐A and cGnRH‐II were found to bind with greater affinity than sGnRH to the goldfish testicular GnRH binding sites. The findings provide the first characterization of testicular GnRH binding sites in a teleost species. © 1993 Wiley‐Liss, Inc.
Regulation of mammalian brain cell volume
Authors: Law R. O. 
Published: June 2005

AbstractMaintenance of brain cell volume is of crucial importance for normal central nervous system (CNS) function. This review considers volume regulation primarily in response to disturbances of body fluid osmolality. Brain cells counter the tendency to swell or shrink by appropriate adjustment of their internal osmotic potential. This is achieved by loss or uptake of inorganic ions and low molecular weight organic solutes (osmolytes). The latter comprise mainly amino acids, myoinositol, choline, and methylamines. Taurine may be of particular importance in volume control, especially in young animals. Brain cell volume regulation, however, is only one contributory factor to maintenance of constant brain volume (water content), and operates in parallel with important alterations in bulk fluid and electrolyte movement across the blood‐brain barrier and between the interstitium and cerebrospinal fluid, which themselves moderate the requirement for transient alteration in cell volume during acute osmotic imbalance. Although altered cerebral content of inorganic ions and osmolytes are usually regarded as responses, respectively, to acute and chronic osmotic disturbances, osmolytes (especially taurine) may also participate in short‐term cell volume regulation. © 1994 Wiley‐Liss, Inc.
Hypoosmotic volume regulation in bivalves: Protein kinase C and amino acid release
Authors: Deaton Lewis E. 
Published: June 2005

AbstractPhorbol esters potentiate the release of free amino acids from isolated ventricles and gills of the mussel, Geukensia demissa, when the tissues are incubated in hypoosmotic seawater. Phorbol esters do not affect the release of amino acids from tissues in isosmotic seawater. Inhibitors of protein kinase C depress the release of amino acids from isolated ventricles in hypoosmotic seawater by 25–30%. Calmodulin antagonists did not inhibit the efflux of amino acids from isolated ventricles in hypoosmotic seawater.The level of inositol 1,4,5‐triphosphate does not change in isolated ventricles incubated in either hypoosmotic or isosmotic seawater. In contrast, there is a transient increase in the level of diacylglycerol in ventricles exposed to hypoosmotic seawater. The increase is detectable 0.5 min after transfer of the tissue to hypoosmotic seawater; 2 min after transfer, there is no difference between tissues incubated in isosmotic and hypoosmotic media.These results suggest that protein kinase C plays a role in the modulation of the release of amino acids from ventricle and gill cells in G. demissa. © 1994 Wiley‐Liss, Inc.
Stimulation of skeletal growth by thyroid hormone administrations in the rainbow trout, Oncorhynchus mykiss
Authors: Takagi Yasuaki , Hirano Joe , Tanabe Hiroshi , Yamada Juro 
Published: June 2005

AbstractEffects of 3, 5, 3′‐triiodo‐L‐thyronine (T3) on the skeletal growth in yearlings of rainbow trout were studied. Groups of rainbow trout maintained at 10–14°C under a natural photo‐period were fed daily to satiation with diets supplemented with 0, 5, 25, and 50 ppm T3 for 2 months. Histological preparations of the ceratobranchial cartilage and pharyngeal bone were observed under a light microscope to compare histomorphometric parameters. The T3 administrations significantly increased plasma T3 (25 and 50 ppm diets) and fork length (50 ppm diets), and depressed the condition factor (25 and 50 ppm diets). Chondrocytes in the hypertrophic zone of the cartilage markedly increased both in size and number (25 and 50 ppm diets). A significant enlargement of osteoid of the bone was observed (50 ppm diets). Bone formation (25 and 50 ppm diets) and resorption (5, 25 and 50 ppm diets) were activated. The results indicated that the oral administration of T3 can stimulate the growth of both cartilage and bone in the rainbow trout. © 1994 Wiley‐Liss, Inc.
Peritrophic matrix of the black fly Simulium vittatum: Formation, structure, and analysis of its protein components
Authors: Ramos Alfredo , Mahowald Anthony , Jacobs‐Lorena Marcelo 
Published: June 2005

AbstractThe peritrophic matrix (PM) (same as peritrophic membrane) is secreted by the midgut epithelium of insects and completely surrounds the ingested food. The PM is likely to influence disease transmission by hematophagous insects. As a prelude to a more detailed examination of PM function, we report on morphological and molecular studies of the PM type 1 (PM1) from Simulium vittatum. The blood meal induces major changes in epithelial cell morphology: cells become flattened, microvilli decrease dramatically in number, and organelles redistribute in the cytoplasm. The PM1 forms within minutes of the blood meal. After 6 h the PM1 has reached its maximum thickness (approximately 13 μm) and strength. Two‐dimensional gel electrophoresis reveals two major PM1‐specific proteins of 66 and 61 kDa. Synthesis of these PM1 proteins is likely to be induced by the blood meal, since they are not detectable prior to blood feeding. The time course of accumulation and disappearance of the PM1 proteins closely correlates with the appearance and disappearance of the PM1 itself. © 1994 Wiley‐Liss, Inc.
Calcium transport across isolated gill epithelium of Carcinus
Authors: Lucu Čedomil 
Published: June 2005

AbstractPreparations of posterior gills isolated from postmoult shore crabs (Carcinus mediterraneus) that had been acclimated to dilute seawater were used for calcium‐transport studies. Gills were perfused and bathed with saline of identical composition, with 45Ca2+ ions added exclusively to the bathing solution or the perfusate for measurement of unidirectional influx or efflux, respectively. The unidirectional influx of calcium (5.57 ± 0.95 μmol h−1 per g gill fresh weight) significantly exceeded the efflux (3.15 ± 1.02 μmol h−1 per g gill fresh weight), indicating a net transgill influx of calcium.Calcium influxes were inhibited when La3+ ions were added apically (IC50 = 7 × 10−6 mol 1−1) or basolaterally (IC50 = 1.6 × 10−6 mol 1−1). In addition, basolaterally applied La3+ ions inhibited effluxes with an IC50 of 3.0 × 10−7 mol 1−1. Amiloride had no significant effect on the unidirectional fluxes of calcium. Influxes of calcium gave a sigmoidal curve when plotted against the external concentration of calcium in the bath. The Hill coefficient (2.66 ± 0.20) suggested that there are at least two or three Ca2+ carrier systems that are active during the influxes of calcium. Moreover, apically added La3+ ions produced a concentration‐dependent inhibition of calcium influx, which is discussed in terms of inhibition of apically located calcium channels. By contrast, the inhibitory action of La3+ ions at the basolateral gill surfaces is discussed in terms of an effect on ATP‐dependent calcium transport and the Na+/Ca2+ exchanger. © 1994 Wiley‐Liss, Inc.
Effects of lung reduction on rheotactic performance in amphibian larvae
Authors: Bruce Richard C. , Beachy Christopher K. , Lenzo Paul G. , Pronych Scott P. , Wassersug Richard J. 
Published: June 2005

AbstractIn this study we test the hypothesis that lung reduction in amphibians is a larval adaptation to reduce buoyancy and facilitate rheotaxis in lotic environments. Larvae of the spotted salamander Ambystoma maculatum (family Ambystomatidae) were raised from eggs with (= control) and without (= experimental) access to the air‐water interface. The experimental larvae developed significantly smaller and more solidified lungs than the controls. Although mean snout‐vent length did not differ between the control and experimental groups, the latter had a significantly greater mean body mass, indicating greater specific gravity in experimentals versus controls. To evaluate rheotactic behavior, larvae were subjected to a water current in an artificial stream. The distance and time required to establish a purchase on the stream bottom were recorded. Although the times did not differ, the distances displaced downstream were significantly less in experimental than in control larvae. We conclude that lung reduction and solidification reduce buoyancy and enhance rheotactic ability in salamander larvae. These findings suggest that lunglessness in plethodontid salamanders evolved as an adaptation to stream environments. © 1994 Wiley‐Liss, Inc.
Patterns of DNA synthesis and mitotic activity during the intermoult of Daphnia
Authors: Beaton Margaret J. , Hebert Paul D. N. 
Published: June 2005

AbstractAmong insects, the epidermal cell cycle pattern is related to the type of ontogenetic development. In taxa undergoing complete metamorphosis, cells are commonly maintained in the G2 stage of interphase between bouts of cell division. In crustaceans, as in insects exhibiting incomplete metamorphosis, it is believed that cells ordinarily remain in G1 for much of the intermoult, with DNA replication occurring late in the moult cycle followed closely by cell division. The present study reveals a differing pattern of epidermal cell division in two distantly related members of the cladoceran crustacean genus Daphnia. Cell cycle kinetics were examined in the last juvenile instar of each species using DNA content determinations and estimates of mitotic frequency. These analyses confirm that each epidermal cell possessed the diploid DNA amount, completed a single cell cycle, and remained in G1 for the majority of the instar. However, DNA replication occurred shortly after moulting and was followed by intense mitotic activity so that cell proliferation was restricted to a short period soon after ecdysis. Cell densities during the instar increased by approximately 60 and 100% for D. pulex and D. magna, respectively. © 1994 Wiley‐Liss, Inc.
Effect of dark rearing on the eye of Gryllus bimaculatus Crickets
Authors: Deruntz Philippe , Palévody Claude , Lambin Michel 
Published: June 2005

AbstractStudies of the visual fields of six species of crickets have shown that the extent of these visual fields is related more to the nature of their habitat than to the phyletic proximity of the species. The present experiments were conducted to determine the influence of light itself on the development of the eye in young Gryllus bimaculatus. When these insects were maintained in total darkness from the first stages of ontogenetic development, they exhibited morphogenetic changes which seem to result in better light energy reception (more numerous ommatidia, smaller interommatidial angles). However, electron microscopic studies revealed fine structural modifications, which are likely to affect vision adversely. We discuss these changes in terms of the visually guided locomotion of the insects in their natural habitat. © 1994 Wiley‐Liss, Inc.