bluuebunny/crossref_metadata_2025_split huggingface dataset:
Production of chimeras in the deer mouse Peromyscus maniculatus bairdi
Authors: Klein Maryrose S. , Markert Clement L. 
Published: June 2005

AbstractThe production of intraspecific chimeras in the deer mouse, Peromyscus maniculatus, was undertaken to make mammals of another genus useful for studies of reproductive biology, developmental genetics, and embryonic development. Peromyscus was generally amenable to the same experimental procedures and techniques employed in producing Mus musculus chimeras. We found that Peromyscus embryos could be successfully manipulated and cultred in vitro. Fertilized eggs and 2‐cell embryos continue cleavage when cultured in vitro and form morulae and blastocysts. Almost all the 4‐ and 8‐cell embryos that were aggregated remained together and developed, after 1 day of culture in vitro, to form chimeric morulae and blastocysts. However, certain changes had to be made in the chimera‐making procedure employed for M. musculus to accomodate some of the differences in reproductive physiology and behavior of Peromyscus. The methods for the preparation of donor females and of foster mothers had to be modified in order to obtain embryos on the scheduled day of the experiment, and to obtain pseudopregnant foster mothers. With these revised precedures, three P. m. bairdi chimeras were produced. Two are healthy fertile males displaying chimerism in the fur. The other chimera was delivered dead at 17 days of gestation, after its foster mother died. Chimerism was detected in the retinal epithelium of the eye by the presence of black pigmented patches contributed by the wild‐type genotype, and unpigmented patches, contributed by the blonde mutant genotype. By developing the procedures enabling the production of the first chimeras in this genus, we have demonstrated that Peromyscus is a suitable animal for exacting technical manipulations in the laboratory.
The molt cycle of the crab, Cancer antennarius: Computer‐aided staging
Authors: Spaziani Eugene , Ostedgaard Lynda S. , Vensel William H. , Hegmann Joseph P. 
Published: June 2005

AbstractSome stages of the molting cycle are not readily discernible in large crustaceans, if classical staging methods are employed. Alternative methods were explored. A statistical classification procedure used in numerical taxonomy, multiple discriminant analysis, was applied to 26 variables measured in crabs (Cancer antennarius) of known stages. Variables were tested systematically for discriminant capacity singly, in pairs, and in linear combinations. A set of 12 variables was found that discriminates stages accurately and efficiently. The variables are physical in character, highly accessible, and easily measured; the required data can be collected routinely before, during, or after an experiment. The method can be applied to staging other species.
Macromolecular synthesis during oral regeneration in the Ciliate Condylostoma magnum: Effects of different inhibitors (II). Protein synthesis and microtubule assembly
Authors: Bohatier Jacques 
Published: June 2005

AbstractMacromolecular syntheses essential to the regeneration of a new oral apparatus in the Ciliate Condylostoma magnum were studied by use of specific chemical metabolic inhibitors. In the present paper we have tried to elucidate the question of protein synthesis required for cytodifferentiation and the problem of microtubule assembly. Postperistomial fragments were exposed to cycloheximide and colchicine, immediately, or at various times after cutting. Protargol‐impreg‐nated cells were observed with a light microscope to control the cytological effects of inhibitors. Continuous exposure to high concentrations of cycloheximide (250 μg/ml) or colchicine (700 μg/ml) completely inhibits oral regeneration. Once oral regeneration is initiated, results differ depending on the time when the drugs are added. Applications during the course of morphogenesis suggest that the different steps of oral regeneration, (1) kinetosome proliferation, (2) adoral, and (3) paroral ciliature differentiation and stabilization, (4) invagination of feeding organelles, (5) formation of food vacuoles, (6) elongation and renodulation of the macronucleus are all dependent upon protein synthesis and are colchicine sensitive. On the other hand we can show that stabilization of new oral ciliature occurs when the typical pattern is restored (transverse kinetosome rows on the left side of the oral area, longitudinal rows on the right side). Then, we can define in Condylostoma, two “stabilization points”, one for adoral ciliature and later another for paroral ciliature. This stepwise stabilization is temporally correlated with the times at which these two structures acquire their definitive organization.
Cyclic AMP concentrations during distal regeneration in Hydra oligactis
Authors: Hill Susan K. , Lesh‐Laurie Georgia E. 
Published: June 2005

AbstractRemoval of the highly innervated hypostome and tentacle regions of Hydra initiates physiological changes that result in selective cellular differentiation and regeneration. Evidence has been presented previously that neural products direct this selective cell differentiation, although the mechanism(s) by which this occurs is not known.This investigation has demonstrated a predictable pattern of cyclic AMP activity following subhypostomal amputation. This pattern of activity demonstrates two major peaks during the first 42 hours of regeneration. This first peak occurs at approximately 12–20 hours of regeneration, at a time when macromolecular synthesis studies showed unremarkable activity. The second activity period occurs in close association with significant increases in DNA and RNA synthesis.
Activation of amino acid accumulation in delayed implantation mouse blastocysts
Authors: van Winkle Lon J. 
Published: June 2005

AbstractDelayed implantation blastocysts remained in a diapausing‐like state when incubated in Na+‐depleted (55 mM) medium. Accumulation of radioactive amino acids remained low when embryos were in low Na+ medium, but increased in the manner characteristic of these embryos when placed in high (124 mM) Na+ medium. Differentiation of blastocysts was apparently arrested in medium containing only 55 mM Na+ since no progress toward formation of trophoblastic outgrowths was made in this medium even when it contained all other compounds required for this process. Low Na+ may prevent uptake of amino acids, such as lysine, essential to outgrowth formation. Accumulation of lysine was Na+‐dependent in blastocysts even though this amino acid is not transported via a Na+‐symport system in most cell types. Glucose deprivation did not affect the increase in the capacity of delayed implantation blastocysts to take up amino acids when incubated in high Na+ medium, and glucose accumulation was not Na+‐dependent. The capacity of delayed implantation blastocysts to take up amino acids was inversely related to the time before these embryos began forming outgrowths in vitro. The latter process occurred more rapidly if diapausing blastocysts had been stimulated in utero by injecting overiectomized mice with progesterone and estrogen. However, these hormones slowed outgrowth formation slightly when present in the culture medium in vitro.
Arylsulphatase activity in seminal plasma from fowl semen
Authors: Droba Maria , Droba Bogusław 
Published: June 2005

AbstractArylsulphatase from seminal plasma of fowl was characterized with a crude enzyme preparation using nitrocatechol sulphate as the substrate. Arylsulphatase activity was considerable and showed a shift of pH optimum dependent on the incubation time and on the presence of sulphate and chloride ions. The electrophoretic pattern of enzymic activity showed three separate bands. It is concluded that both arylsulphatases A and B may be present in seminal plasma.
A histological examination of the pars distalis from the syrian hamster mutant anophthalmic white (Wh)
Authors: James Susan C. , Asher Jr. James H. 
Published: June 2005

AbstractThe gene, Wh, causing anophthalmia in the Syrian hamster, Mesocricetus auratus, is a highly pleiotropic gene which has profound effects upon eye development, pigmentation, and reproduction. Hamsters homozygous for this gene also possess abnormalities in testicular size and composition which may be related solely to the lack of the visual pathway acting by means of altered pituitary function. The objective of this study was to determine whether morphological abnormalities existed in hypophyses of male hamsters homozygous for the mutant gene Wh. Accordingly, hypophyses from 10 normal, 10 heterozygous, 10 homozygous mutant, and 5 normal enucleated animals from the AN/As‐Wh strain were compared at the light and electron microscopic level. At the light microscopic level, glands from anophthalmic individuals contained 33% fewer cells and many of the cells present either resembled signet ring cells or folliculostellate cells. At the electron microscopic level, many cells from Wh homozygotes were greatly enlarged, contained only a few organelles and few to no secretory granules. In addition to the glandular cell types, agranular follicular cells were prevalent. Cells with numerous cilia, basal bodies, and a 9 + 2 microtubule configuration were also found within mutant glands. Since pituitaries from hamsters homozygous for Wh displayed far different morphological characteristics than did pituitaries from normal, heterozygous, or normal enucleated animals, it is postulated that either the gene (Wh) acts to alter cellular differentiation of the embryonic hyophysis or that the gene causes abnormal dedifferentiation in the adult.
Temperature‐sensitive periods of sex determination in emydid turtles
Authors: Bull J. J. , Vogt R. C. 
Published: June 2005

AbstractIn many turtles sex differentiation is controlled by the incubation temperature of the embryo, with low temperatures producing males, high temperatures producing females. This study investigates the developmental period of temperature‐sensitivity in two species of emydid turtles, using different combinations of incubation at a male‐determining temperature (25°C) and at a female‐determining temperature (31°C). The sensitive period extends throughout much of the middle third of development. Sex is more readily influenced by 25° than by 31°, however, so that maleness can be determined much earlier in development than can femaleness. Comparison of these results with a previous study of snapping turtles indicates that the sensitive period occupies somewhat the same developmental interval in these different turtles. However, in snapping turtles, the female‐determining temperature used (30°) is more influential than the male‐determining temperature (26°), in contrast with these results from emydids.
Suppression of first cleavage in the mexican axolotl (Ambystoma mexicanum) by heat shock or hydrostatic pressure
Authors: Gillespie Laura L. , Armstrong John B. 
Published: June 2005

AbstractAndrogenetic diploid axolotls were produced by ultraviolet inactivation of the egg pronucleus shortly after fertilization, followed by suppression of the first cleavage division by hydrostatic pressure or heat shock. After treatment at 14,000 psi for 8 minutes, diploidy was restored in 74% of the embryos, but only 0.8% survived to hatching. A 36–37° C heat shock of 10‐minutes duration, applied 5.5 hours after the eggs were collected, yielded a slightly lower percentage of diploids. However, the proportion surviving to hatching was significantly greater (up to 4.6%). A second generation of androgenetic diploids was produced from one of the oldest of the first generation males with a similar degree of success. The lack of significant improvement suggests that the low survival is due to the heat shock per se and not to the uncovering of recessive lethal genes carried by the parent.
Glucose transport across ocular barriers of the spiny dogfish, Squalus acanthias
Authors: Dimattio Joseph , Zadunaisky Joseph A. 
Published: June 2005

AbstractEvidence is presented demonstrating that in the dogfish, Squalus acanthias, D‐glucose is transported from the blood to the ocular fluid compartments by a mechanism that is consistent with carrier‐facilitated transport. Across the dogfish aqueous barrier D‐glucose is transported 8.4 times faster than L‐glucose, whereas this D/L transport ratio is only 5.5 in the rat. Similarly, the D/L transport ratio is 12.7 across the dogfish vitreous barrier and only 6.1 across this barrier in the rat. It is estimated that per unit area of vitreous barrier, the rat transports D‐glucose faster than the dogfish but also has a greater passive permeability, as measured by L‐glucose, and transport is therefore less efficient. Urea transport was found to be faster than L‐glucose transport, suggesting a transport mechanism for urea other than simple diffusion. The sectional analysis of frozen vitreous humor indicated that the lens of the dogfish is supplied with D‐glucose from both the ciliary epithelium and across the retinal pigment epithelium, while the retina receives D‐glucose primarily across the pigment epithelium.
Involvement of the circadian system in photoperiodic regulation of insect antifreeze proteins
Authors: Horwath Kathleen L. , Duman John G. 
Published: June 2005

AbstractSeveral species of insects produce proteins in the winter that depress the hemolymph freezing and supercooling points thereby functioning as antifreezes. These proteins produce a thermal hysteresis (difference between the freezing and melting points). This study concerns the environmental and physiological mechanisms that regulate the seasonal production of antifreeze proteins in the beetle, Dendroides canadensis. Larvae collected in early fall from a natural population and acclimated to a short photoperiod (8L/16D at 20°C, 90% RH) elevated levels of thermal hysteresis proteins (THPs), whereas those individuals maintained on a long (16L/8D) photoperiod did not. “Resonance” experiments showed that circadian rhythmicity is involved in the photoperiodic timing mechanism used by Dendroides to control antifreeze production. These results suggest that an important aspect of insect seasonality ‐ i.e., winter hardening ‐ includes complex biological timing processes of circadian nature.
Morphogenetic movements and fate map of the cypriniform teleost, Catostomus commersoni (lacepede)
Authors: Ballard William W. 
Published: June 2005

AbstractThe morphogenetic movements of Catostomus commersoni have been charted from the onset of epiboly to the envelopment of the yolk, by means of chalk markers implanted among the moving blastomeres. A fate map has been worked out for the late cleavage stage just before start of the patterned movements. Results from this species are compared with those for Salmo gairdneri which is a member of a different superorder and is the only other teleost for which the morphogenetic movements are known in detail. Eggs of the two species differ markedly in size, yolk content, and rates of cell movement, but they accomplish the assemblage of their organ systems in the same general way, with no more differences than are known within the group of urodeles, or of anura. Their fate maps are three‐dimensional and closely alike, and markedly different from those of other vertebrates, even of chondrostean fishes. The uniquely teleostean combination of features includes the early bipolar differentiation, the enclosure of the liquid yolk in a syncytial layer, the nonparticipation of the precociously formed surface epithelium in major organ formation, and the three‐dimensional sorting out of the germ layers by different tendencies of cell migration associated with blastomeres lying at different depths in the early blastodisc, as well as other wellknown peculiarities of organogenesis. The question remains whether all teleosts follow the path of Salmo and Catostomus, but these two point to major innovations in early embryonic development at some time during teleostean evolution.
Formation of the leg neuromuscular system in embryos of the cockroach, Periplaneta americana: I. Light microscope studies
Authors: Denburg Jeffrey L. , Fülöp Zoltán 
Published: June 2005

AbstractEmbryos of the cockroach, Periplaneta americana, were examined each day of their 32‐day developmental period. The interval between the first detection of leg rudiments and hatching was divided into 18 stages defined by a characteristic external morphology. Embryos of stages 1, 2, 3, 6, and 8, corresponding approximately to 6½, 7½, 9¼, 11, and 15 days of age, respectively, were examined in detail for changes in external leg morphology, development of thoracic ganglia and leg muscles, and the formation of connections between the two. These observations were based on a light microscopic analysis of serial sections through three different planes. A proximal distal gradient of muscle development within the leg was observed, the cellular events of which were described. The formation of connections between neurons in the thoracic ganglia and cells in the leg was inferred from observations of the extent of axon growth and the state of differentiation of the cells. The innervation of the coxal muscles may occur as early as stage 6. The role of pioneer neurons, sheath cell and body epithelium in guiding axon growth is discussed. The information in this report will serve as a guide in subsequent more detailed electron microscopic studies.
Viability under the testis capsule of inner cell masses isolated from TOr/TOr mouse embryos
Authors: Fujimoto H. , Yanagisawa K. O. , Urushihara Hideko 
Published: June 2005

AbstractSingle inner cell masses (ICM) isolated by immunosurgery from late blastocysts were able to develop into benign teratomas under the testis capsule after 1 month with a frequency of 76%. This technique was used to examine viability and developmental potency of embryos homozygous for the TOr mutation. The number of teratomas formed by the ICMs derived from TOr/+ × TOr/+ crosses was consistent with what is expected if TOr/TOr ICMs did not produce them. After ectopic culture for a short period, presumed TOr/TOr ICMs gave rise to abnormal spherical structures resembling embryonic parts of the mutant embryos at the egg cylinder stage. These results suggest that TOr/TOr ICMs have greatly decreased competency for developmental potency.
Axonal guidance in the neuroepithelium of the tail of the trout Salmo gairdneri
Authors: Geraudie Jacqueline , Singer Marcus 
Published: June 2005

AbstractAxonal growth has been studied in the ependyma of the developing trout tail. Results of the ultrastructural investigation show that intercellular spaces or channels develop in advance of the growth of the pioneering neurites. This developmental process is reminiscent of the axonal patterning described in the growing ependyma of the newt. It gives some additional support to the “blueprint hypothesis” as presented by some of us (Singer et al., '79), which assign to the glial cells “the pattern of the primary neuronal pathways”.
Lung phospholipids in the embryonic and immature chicken: Changes in lipid composition and biosynthesis during maturation of the surfactant system
Authors: Hylka Vincent W. , Doneen Byron A. 
Published: June 2005

AbstractTotal phospholipid and its components were measured in lungs of the embryonic chick, and in tissue, lamellar bodies, and lavage fluid after hatching. Phosphatidylcholine (PC), the major phospholipid in surfactant, was fractionated and the amount and fatty acid composition of its disaturated (DSPC) component was determined. The synthetic rates of PC, DSPC, and other choline phospholipids were determined on days 14 and 19 of incubation from incorporation of 14C‐choline. Choline pool size was also estimated at these times. Phospholipid content of the lung increased most rapidly after day 18 of incubation with the greatest increase in PC. The PC synthesized just prior to breathing was enriched in DSPC, which constituted 45% of PC on day 19 and only 30% on day 14. DSPC content was even lower in embryonic liver and yolk. Incorporation of 14C‐choline in vitro into pulmonary PC, Sphingomyelin (Sphingo), and DSPC was greater in birds before breathing (day 19) than in the younger embryos. Choline pool size decreased between days 14 and 19 of incubation, but the synthetic rate of DSPC doubled in this interval. Increased accumulation and biosynthesis of pulmonary PC, Sphingo, and DSPC in lung tissue of the embryo paralleled appearance of lamellar bodies. In 5–6‐week‐old chickens the major pulmonary phospholipid was also DSPC. In lavage, 70% of PC was DSPC, predominantly dipalmitoyl PC. As in the mammalian lung, PC, especially its DSPC component, forms the major phospholipid of avian surfactant, and the synthesis of DSPC is specifically stimulated prior to breathing.
Prelethal symptoms of the killing action of some non‐kappa killers in the Paramecium aurelia complex
Authors: Jurand A. , Rudman B. M. , Preer J. R. 
Published: June 2005

AbstractChanges occurring in sensitive paramecia following exposure to non‐kappa killer stocks bearing gamma, lambda, and sigma symbionts were investigated at the light and electron microscopic levels. The responses of sensitive cells to all these killer paramecia are the formation of large numbers of lysosomes, gradual degeneration of mitochondria, loss of ribosomes, production of autophagic vacuoles, and formation of blebs on the pellicle. In some cases the ultrastructure of macronuclei is affected and pellicular blebs are formed inside the cytopharynx. In addition, many of the investigated stocks cause the sensitive animals to lose the ability to discharge trichocysts when tested with a solution of saturated picric acid.
The importance of the presence of metabolizable sugars in a medium for in vitro fertilization of hamster eggs with postovulatory oviduct contents
Authors: Imai H. , Niwa K. , Iritani A. 
Published: June 2005

AbstractHamster eggs with postovulatory oviduct contents were added to a simple defined medium, without serum albumin, but supplemented with different combinations of energy sources. They were then inseminated by epididymal spermatozoa. In a medium containing D‐glucose but without pyruvate and/or lactate, high proportions of acrosome‐reacted spermatozoa (78–94%) and eggs undergoing fertilization (89–96%) were obtained 9–9.5h after insemination. With only pyruvate or lactate as substrates, or with both pyruvate and lactate, acrosome reactions occurred in only 2–4% of the sperm. When D‐glucose ranging in concentration from 2.78 to 8.34 mM was added, a high proportion (82–95%) of the eggs inseminated were found to be fertilized. Substituting D‐galactose, L‐glucose, L‐fucose, D‐lactose, or D‐saccharose for D‐glucose resulted in very low numbers of acrosome‐reacted sperm (0–12%) and fertilized eggs (0–7%). However, in the presence of metabolizable sugars, such as D‐mannose or D‐fructose, the acrosome reaction was seen in 78–85% of the sperm examined and 87–95% of the eggs tested were fertilized.