bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphogenetic gradients in multiple‐graft Hydra viridis. I. The effects of colcemid and colchicine
Authors: Shostak Stanley , Adams James A. 
Published: June 2005

AbstractThe morphogenesis of so‐called secondary (2°) heads, budding regions and feet, and separations at graft borders is studied in multiple‐graft animals containing three gastric regions (3g animals) treated with Colcemid or colchicine. Control animals consist of three non‐treated pieces. Animals consisting of two non‐treated and one treated piece are also employed. The main effects of Colcemid are the promotion of graft healing at the distal graft border, and of 2° head formation on the proximal gastric region (g‐1). Colchicine also promotes graft healing at the distal graft border, but in contrast to the effect of Colcemid, promotes the formation of ectopic feet (tertiary feet) and inhibits head regeneration at the distal end of the middle gastric region (g‐2). Colchicine also accelerates an inversion of polarity in 2° budding regions on the g‐2 pieces of animals with 2° heads on their g‐1 pieces. Treatment of a distal graft piece with Colcemid promotes 2° head formation on the nearest proximal piece which is not treated, but the inhibition of 2° head formation by colchicine occurs only on colchicine treated pieces. The morphogenetic effects of the drugs are interpreted as consequences of their actions on nerve differentiation and cell division. The paper argues that homeostatic control of a hydra's cell population depends on dividing cells influencing cell loss, and that similar mechanisms are involved in the rejection of a graft and the separation of a bud.
Parthenogenic development after chemical treatment of Xenopus laevis spermatozoa
Authors: Jones Pamela , Jackson H. , Whiting M. H. S. 
Published: June 2005

AbstractEggs of Xenopus laevis were fertilized in vitro by spermatozoa pre‐treated with various concentrations of aziridinyl urea (ethyleneurea) for between 30 and 120 minutes. At 2 and 4 mg/ml for 30 minutes there was a high incidence of abnormal embryos, few of which developed into tadpoles; after 6 and 8 mg/ml no tadpoles were produced. However, the highest concentration, 10 mg/ml, yielded 66% of tadpoles, only 7% of which were obviously abnormal. With increasing time the same pattern of events was obtained except for a displacement towards the lower concentration ranges. Tadpoles developing from these latter experiments were found to be haploid. The results resemble those obtained by exposure of Rana pipiens spermatozoa to X‐rays and ultraviolet light, with the production of gynogenetic embryos, usually referred to as the Hertwig effect.
Tissue interaction: Morphogenesis of the lateral‐line system and labyrinth of vertebrates
Authors: Merrilees M. J. 
Published: June 2005

AbstractA cord of specialized epithelial cells is present in the canals of the lateral‐line system and membranous labyrinth. Transplant experiments suggest that these cells control the deposition pattern of surrounding connective tissues such as scale, cartilage and bone, and thus play a significant role in control and maintenance of canal morphology.
Relationship between two kinds of hatching enzymes in the hatching liquid of the medaka, Oryzias latipes
Authors: Yamagami Kenjiro 
Published: June 2005

AbstractThe relationship between the hatching enzymes I and II of the medaka, Oryzias latipes, was studied by examining their behavior on gel filtration column chromatography and their responsiveness to added reagents including certain inhibitors. Enzyme I, of higher molecular weight, could be converted to the lower molecular weight enzyme II during purification. The results support the conclusion that enzyme I is a complex form of enzyme II combined with another substance.
Mouse embryo development in vitro: Effects of inhibitors of RNA and protein synthesis on blastocyst and post‐blastocyst embryos
Authors: Rowinski Jan , Solter Davor , Koprowski Hilary 
Published: June 2005

AbstractThe effect of inhibitors of RNA synthesis (Cordycepin, Actinomycin D) and protein synthesis (Cycloheximide) on the development and growth of mouse blastocysts in vitro was explored. Blastocysts exposed in vitro for 24 hours to 50 μg/ml Cordycepin, 0.005 μg/ml Actinomycin D, or 0.1 μg/ml Cycloheximide grew and began to attach to the dish in the similar manner as did the controls. Cell number, 3H‐thymidine‐labeling index and mitotic index in treated blastocysts were also similar to controls. Control blastocysts grown in vitro for six days attached to the dish, trophoblastic layer was spread and inner cell mass continued to grow and formed an egg‐cylinder like structure. Blastocysts grown in constant presence of 50 μg/ml of Cordycepin in the medium or those exposed to inhibitor only for the first 24 hours failed to develop inner cell mass derivatives in culture, although the growth of trophoblastic cells was as in controls. The same results were obtained if blastocysts were exposed to 0.005 μg/ml of Actinomycin D or to 0.1 μg/ml of Cycloheximide either continuously or for the first 24 hours. Higher concentrations of Actinomycin D (0.05 μg/ml) or Cycloheximide (1 μg/ml) were toxic for the blastocysts causing their degeneration within 24–48 hours. Our results suggested that appropriate concentrations of RNA or protein synthesis inhibitors could prevent the development of inner cell mass derivatives with essentially no effect on the development of primary trophoblast. This would indicate that the process of differentiation of inner cell mass cells is much more sensitive to metabolic inhibitors than the differentiation of giant trophoblastic cells.
Effect of prolactin on sugar and amino acid transport by the rat jejunum
Authors: Mainoya James R. 
Published: June 2005

AbstractAfter two daily ovine prolactin injections in rats, significant increases in jejunal absorption of glucose, glycine and proline, as well as of fluid and NaCl, occurred. Although ouabain caused dramatic reductions in fluid, sodium, chloride and glucose transport, prolactin had an effect even in the presence of ouabain. Mucosal hyperosmolality significantly decreased fluid, sodium and chloride absorption but had no significant effect on glucose transport. Addition of prolactin in vitro had no effect on intestinal absorption. Prolactin‐induced increases in transport of fluid, NaCl and organic nutrients by the mammalian jejunum may play an important role in nutritional and osmoregulatory adaptations.
Osmoregulation in the fresh water sponge, Spongilla lacustris
Authors: Brauer Elizabeth B. 
Published: June 2005

AbstractExternal medium passed through the canal system of small Spongilla lacustris at the rate of 70 body volumes per hour, allowing for little or no modification of its composition by the animal. Consequently any osmotic gradient between medium and animal was experienced at the cell level. Forty or more contractile vacuoles arranged around the nucleus in each basal pinacocyte removed fluid at the rate of 24.7 ± 1.0 μm3/cell/min in 1.3 milliosmolal (mosm) medium. Output of the contractile vacuoles depended in a nearly linear fashion on the osmotic concentration of the medium, decreasing to zero at 12–16 mosm. The contractile vacuoles responded to the osmotic concentration of the medium, not to ionic strength or the concentration ratios of particular ions. Osmotic concentration of the vacuolar fluid can be estimated as 10–40 mosm, leading to the hypothesis that contractile vacuoles of sponges function by isotonic water separation.
Form and pattern in ciliated protozoa: Analysis of a genic mutant with altered cell shape in Tetrahymena pyriformis, syngen 1
Authors: Doerder F. P. , Frankel J. , Jenkins L. M. , Debault L. E. 
Published: June 2005

AbstractA single cell isolated from the sexual progeny of mutagenized parents gave rise to a clone of cells with an abnormal, conical shape. Breeding analysis revealed that this shape results from the action of a single recessive gene, co (conical). Homozygous mutant cells are shorter and wider than wild type cells, and have their widest point at a more posterior position. Nonetheless, cortical parameters such as number of ciliary rows, number of ciliary units within these rows, and positions of contractile vacuole pores remain essentially unchanged in conical cells, suggesting a considerable degree of mutual independence of pattern and form.Shape changes prior to cell division bring about some convergence in form of dividing conical and wild type cells. However, in conical cells the new oral apparatus and fission line form well posterior to the cell equator, so the opisthes are invariably smaller than proters. Macronuclei nonetheless undergo constriction at the normal central location, and the characteristic inequality in the DNA content of the two macronuclear division products is not increased by the conical condition.Generation times are, on the average, nearly the same in the two wild type daughter cells and in conical proters, while the small conical opisthes have generation times averaging one‐third longer. This prolongation explains why population doubling times are always somewhat longer in cultures of conical cells than in parallel cultures of wild type cells. The unusually long generation times of conical opisthes allows for the compensation of initial size differences.Observations on shape changes in conjugating cells of various genotypic combinations suggest that the wild type gene product is not freely exchangeable across the conjugation bridge.The implications of the conical phenotype for problems of cellular patterning and positioning of organelle systems are considered in the DISCUSSION.
Microfibrillar structures in the nucleus and cytoplasm of amoeba proteus (1)
Authors: Leeson T. S. , Bhatnagar R. 
Published: June 2005

AbstractThe presence of microfibrillar structures in the nucleus and cytoplasm of Amoeba proteus has been described after glutaraldehyde and osmium fixation. The possible roles of cytoplasmic microfibrils in the contraction process of amoeba and nuclear microfibrils in the formation of the honeycomb nuclear lamina are discussed.
The effect of prolactin and thyroxine on tail resorption in R. pipiens: In vivo and in vitro
Authors: Derby A. 
Published: June 2005

AbstractThyroxine induces tail resorption in anurans both in vivo and in vitro. This event is accompanied by an increase in the activity of the hydrolytic enzymes acid phosphatase and B‐N‐acetylglucosaminidase. Prolactin treatment promotes tail growth and directly antagonizes the action of thyroxine on tail tissues. This is evident at the gross morphological level as well as at the biochemical level where prolactin inhibits the increase in activity on the hydrolytic enzymes that occurs during thyroid hormone induced resorption.
Pattern formation in the imaginal wing disc of Drosophila melanogaster: Fate map, regeneration and duplication
Authors: Bryant Peter J. 
Published: June 2005

AbstractFragments of the wing disc of Drosophila (fig. 2) were either injected into mature third instar larvae for immediate metamorphosis, or cultured in adult abdomens for seven days before being transferred to larvae for metamorphosis. The structures differentiated during metamorphosis were then analysed. The results of the first series of experiments were used to construct an accurate fate map of the disc, and those of the second series were used to determine the regenerative properties of the disc.The fate map (fig. 7) shows presumptive proximal parts (notum, pleura, and dorsal and ventral hinge) at the two ends of the disc, with presumptive distal wing parts in between. During metamorphosis the disc epithelium folds upon itself along the presumptive wing border, bringing dorsal and ventral wing and hinge surfaces into apposition. The wing surfaces occupy a much smaller relative area, and the hinge parts a much larger relative area, in the fate map than in the adult structure.The cultured fragments, in general, behaved in accordance with the rule that when two cut surfaces are created by cutting across the disc, regeneration occurs from one of the cut surfaces and duplication occurs from the other (fig. 14). It was possible to define a level in the longitudinal axis of the disc from which regeneration proceeds outwards. Cut surfaces facing away from this level show regeneration, while cut surfaces facing this level undergo duplication. Similar behavior was found for the transverse axis, and for two diagonal series of cuts.Some fragments with two cut edges could regenerate from one edge while duplicating from the other, whereas others could regenerate from two cut edges simultaneously. However, fragments with four cut edges showed incomplete regeneration, and a high tendency to duplicate even though regeneration in all directions might have been expected on the basis of the other experiments.
An organized distribution of acrosomal proteinase in rabbit sperm acrosomes
Authors: Stambaugh Richard , Smith Monica , Faltas Samiha 
Published: June 2005

AbstractAcrosomal proteinase was found to be present in a highly organized distribution within the acrosomes of rabbit spermatozoa by cytochemistry. This distribution consists of at least six linear loops of evenly spaced proteinase granules, which run diagonally across the flat side of the sperm head in a criss‐crossing pattern with the two most anterior loops surrounding the region of the acrosome reaction. This is the first description of an organized distribution of enzymes within a lysosome‐like organelle.
Cell patterns and cell movements during early development of an annual fish, Nothobranchius neumanni
Authors: Lesseps R. J. , van Kessel A. H. M. Geurts , Denucé J. M. 
Published: June 2005

AbstractDuring epiboly stages the cells (called deep blastomeres) which will form the definitive embryo disperse over the surface of the yolk sphere, only later aggregating and developing an embryonic axis. Five different statistical tests were used to study the pattern formed by the deep blastomeres during epiboly and early dispersed stages. The two most reliable tests, based on the distance from each deep blastomere within a selected area to its nearest neighboring cell, indicate that the distribution pattern changes from regular during epiboly stages to random during dispersed stages 1 and 2. Careful observation and time‐lapse microphotography revealed some aspects of how the cells set up the regular pattern. The deep blastomeres exhibit a variety of cell extensions, with which they often contact one another. When two deep blastomeres make contact during epiboly stages, they soon break the contact and move apart; they overlap one another only rarely. Deep blastomeres are frequently located at, and are even elongated along, borders of the overlying flat cells (enveloping layer cells). These two mechanisms, one similar to contact inhibition of cell movement, the other to contact guidance, may contribute to the rather regular spacing of the deep blastomeres as well as to their arrangement in rows during epiboly stages.
A preliminary investigation into the roles played by the rectal gland and kidneys in the osmoregulation of the striped dogfish Poroderma africanum
Authors: Haywood Geoffrey P. 
Published: June 2005

AbstractPresented here are the results of a preliminary investigation into ionic and osmotic regulation by the kidneys and rectal gland of the striped dogfish, Poroderma africanum. Fish with ligated rectal glands showed an increase in blood concentration of sodium and chloride within a short time period, reaching a maximum after four days. The blood concentration of the two ions then decreased over the following ten days. Control animals showed relatively unchanged blood‐sodium and chloride levels, over the entire 14‐day period.After salt loading, both control animals and those with ligated rectal glands showed initial rise in blood sodium and chloride levels, but these returned towards initial values within seven hours of injection. Comparison of the two groups indicates that the rectal gland may control blood‐chloride levels more so than ‐sodium, although its action as a salt regulator does not seem very pronounced in either case. Urine and rectal gland fluid, were collected as a compound fluid, from normal fish, and the estimated cloacal salt loss is discussed. Urine from normal fish was also collected separately and was analysed for its contribution to salt loss. Results are discussed and compared with previous relevant findings.
Adult leg formation during metamorphosis of the silkworm Bombyx mori and its disturbance by exogenous ecdysone
Authors: Hasegawa Kinsaku , Ata Ahmed Mohamed 
Published: June 2005

AbstractAdult leg formation from pupal legs of simple construction was histologically and histochemically studied using the tibiae of mesothoracic legs of Bombyx mori. The hypodermis detaches from the pupal cuticle one day after pupation and migrates as a whole to the center of the tibia to form a tube‐like adult hypodermis at three days of age. During this process, differentiative cell divisions are observable in full swing one to two days after pupation.In the mesothoracic leg of fresh pupa, the tibial cavity is divided into two sinuses by a septum. The outer sinus facing the outer side of the leg contains a trachea running straight along the leg. This trachea differentiates into an air‐sac in the tibia of the adult. The tracheal epithelial cells undergo mitoses while moving close to the septum. The epithelium separates from the taenidia and expands in two directions outwardly alongside the septum and towards the hypodermis of the leg, the process of which seems to be achieved by filaments presumably formed by granular cells connecting the epithelium to the basement membrane from one side and to the septum from the other. Retraction of these filaments results in a pulling mechanism which continues gradually until the epithelium is fully stretched and fused with both the basement membrane and the septum to form an air‐sac in the tibia.Differentiation processes of pupal legs into adult ones such as the mitoses of both hypodermis and tracheal epithelium, the expansion of the epithelium by filaments formed by granular cells, etc., are blocked when exogenous ecdysone is administered in excess in fresh pupae.
The differential effects of estrogen and progesterone on the uterus of the ovariectomized golden hamster
Authors: Rath Narayan C. , Prasad M. R. N. 
Published: June 2005

AbstractThe effects of estrogen and progesterone on incorporation of 3H‐thymidine by the uterus of the ovariectomized hamster are reported.In the ovariectomized hamster progesterone alone did not induce incorporation of 3H‐thymidine. Estrogen alone caused significant incorporation of 3H‐thymidine, predominantly in the luminal epithelium whereas a prior or subsequent treatment with progesterone activated DNA synthesis in the stroma and muscularis. These results indicate the role of estrogen in priming the uterus of the hamster for the subsequent action of progesterone.
The physiological basis for changes in the freezing tolerance of intertidal molluscs. I. Response to subfreezing temperatures and the influence of salinity and temperature acclimation
Authors: Murphy Dennis J. , Pierce Sidney K. 
Published: June 2005

AbstractAcclimation to either low temperature or high salinity increased the freezing tolerance of the intertidal mollusc, Modiolus demissus demissus (Dillwyn). Lethal freezing temperatures ranged from −5.11°C to −12.16°C when mussels were acclimated between 12.1o/oo and 33.9o/oo (15°C). Acclimation to 45.5o/oo, however, did not increase freezing tolerance above the value obtained at 33.9o/oo. Lethal freezing temperatures also ranged from −10.4°C to −13.76°C in winter mussels acclimated between 23°C and 0°C (34o/oo). Thermogram recordings of intact M. demissus exposed to various subfreezing temperatures indicated that freezing occurs extracellularly only. Consequently, freezing mortality apparently results from cell dehydration as a critical amount of tissue water is lost as ice. Calorimetry on adductor muscles isolated from M. demissus acclimated to various salinities showed that increasing salinity acclimation increases freezing tolerance by reducing the amount of tissue water frozen and, thus, preventing the attainment of a lethal dehydration level. These calorimetric studies also suggested that the lack of further increases in freezing tolerance above a specific salinity acclimation may result from salt concentrations reaching a toxic level in the frozen tissue. On the other hand, calorimetry showed that the amount of tissue water frozen is independent of temperature acclimation. Thus, low temperature acclimation does not act to increase freezing tolerance by reducing the amount of tissue water frozen but, rather, acts through an unspecified mechanism to increase cellular tolerance to greater levels of dehydration and, possibly, to greater concentrations of toxic salts.
DNA‐RNA bodies in midgut cells of the stick insect, Bacillus rossius
Authors: Scali Valerio , Montanelli Elisa 
Published: June 2005

AbstractIn the anterior part of the midgut and in the Malpighian tubules of the stick insect Bacillus rossius, about 10% of the epithelial cells develop endonuclear bodies which appear as DNA‐RNA masses; in these cells the usual nucleoli are no longer evident. The DNA‐RNA bodies are first formed in third instar larvae, become numerous in the fourth instar and persist in adults. In all larval instars and adults a different kind of DNA‐body has been noticed in the epithelial cells of the posterior midgut. The DNA‐RNA bodies of the anterior midgut and of the Malpighian tubules have been interpreted as the result of somatic gene amplification, whereas the DNA masses of the posterior midgut are likely due to a virus infection.
Fertilization of green frog (Rana clamitans) eggs in their native jelly by bullfrog (Rana catesbeiana) sperm
Authors: Elinson Richard P. 
Published: June 2005

AbstractFertilization of R. clamitans eggs in their native jelly occurred when inseminated with high concentrations of R. catesbeiana sperm. Contrary to previous evidence, the block to cross‐fertilization of the R. clamitans × R. catesbeiana hybrids may form in nature.
Are we learning what actually goes on when the brain recognizes and controls?
Authors: Bullock Theodore Holmes 
Published: June 2005

AbstractDrawing upon recent advances in neuroscience for examples, the thesis is defended that, in contrast to a Kuhnian view of progress by over‐turning whole sciences, progress amounting to revolution in our understanding of nervous systems is happening by the accumulation of many discrete discoveries, and that this process may be expected to continue for a long time.Twelve propositions are put forward illustrative of ideas developed during and influenced by C. L. Prosser's career, all in the segment of neuroscience concerned with subsystem organization. They range from the generally accepted to the frankly polemical and the merely heuristic.
Ongoing background activity has different forms.
Codes, both spike and graded, are several.
Integrative variables in neuron function are several.
Identifiable cells may be widespread.
Neuronal circuits for behavior are known.
Redundancy is usually overlap.
Reliability can be high.
Recognition neurons may be common and complex.
Command neurons may be common and complex.
Pattern is often central in origin.
Hierarchies and switches may be common.
Subsystem function is an intellectual challenge.
Each of these is briefly elaborated and its logical relation to the others suggested. The role of discrete discovery is thus illustrated — in the generation of new conceptual frameworks that gradually become interrelated and cumulatively change profoundly our picture of what's going on in the brain.