bluuebunny/crossref_metadata_2025_split huggingface dataset:
The developmental biology of annual fishes. II. Naturally occurring dispersion and reaggregation of blastomeres during the development of annual fish eggs
Authors: Wourms John P. 
Published: June 2005

AbstractComplete dispersion and subsequent reaggregation of pre‐embryonic blastomeres, features characteristic of annual fish development, are analyzed in Austrofundulus myersi Dahl. Cleavage produces a typical teleost blastoderm. During the mid‐blastula stages, blastomeres segregate into two populations; deep blastomeres which disperse, and outer blastomeres which form the enveloping cell layer. When epiboly of the enveloping cell layer and periblast commences, the deep blastomeres come together as a consolidated mass and then migrate outward as amoeboid cells. When epiboly has concluded, the deep blastomeres are completely dispersed. After a few days, these cells come together to form a definitive aggregate within which embryogenesis occurs. The reaggregation process was quantified in vivo by determining “coefficients of dispersion.” Amoeboid blastomeres were found to be: uniformly distributed when epiboly is completed (day 2); randomly distributed on day 3; and aggregated on day 4.The origin of the annual fish developmental pattern has involved the spatial and temporal dissociation of the processes of epiboly and embryogenesis. This has been accomplished by the interposition of the dispersion‐reaggregation phases. They may represent an exaggeration of the phases of incipient dispersion and localized aggregation which occur in most teleosts. The dispersion‐reaggregation process is considered to be a control mechanism operating on the principle of a requirement for “critical cell mass” as a necessary prelude to the primary events of embryogenesis. The survival value of the dispersed phase is discussed.Comparative studies of 43 closely related species have shown that the dispersion‐reaggregation pattern is present only in those cyprinodont fishes with annual life cycles. This group includes members of the following genera: Aphyosemion (annual species only); Austrofundulus; Cynolebias (including Cynopoecilus); Nothobranchius; Pterolebias; Rachovia; and Roloffia. Non‐annual cyprinodonts develop as do other fishes. Some Aphyosemion species have transitional developmental patterns.
Chloride and the generation of amniotic fluid in the early embryo
Authors: Faber J. Job , Gault Charles F. , Green Thomas J. , Long Lawrence R. , Thornburg Kent L. 
Published: June 2005

AbstractThe concentrations of chloride in the amniotic fluid of the four and one‐half day chick embryo exceed those in the blood plasma and in the sero‐amniotic fluid. The electrical potential of the amniotic fluid is negative compared to the electrical potentials of the plasma and sero‐amniotic fluid. Nevertheless, the amniotic fluid volume continues to grow without a sensible diminution of its chloride concentration. There is evidence, therefore, of non diffusional influx of chloride into the amniotic fluid.Radioactive chloride injected into the blood stream of the embryo also indicates
that chloride is transferred into the amniotic fluid partly by an active process.
Similar experiments with sodium ion fail to unequivocally demonstrate the
existence of a sodium pump.From these measurements the rate of transfer of chloride by a chloride pump
and the rate of efflux of chloride under the influence of the electrochemical
gradient were calculated. The calculated net influx of chloride agrees with
the net influx calculated from the observed growth rate of the amniotic fluid,
and the same is true for sodium. It is postulated that a metabolically driven
transfer of chloride into the amniotic cavity is an early step in the generation
of the amniotic fluid.
The function of the middle ear in lizards: Divergent types
Authors: Wever Ernest Glen 
Published: June 2005

AbstractThe anatomy of the middle ear and auditory sensitivity in terms of the cochlear potentials have been studied in 12 lizard species whose conductive mechanisms show various forms of divergence from normal. In addition, results are given for two normal species for purposes of comparison.Three forms of defect are found that impair the reception of sounds and reduce the effectiveness of their action on the sensory cells of the cochlea. These are the absence of the tympanic membrane, the interposition of a muscle mass barring direct access of the ear to the exterior, and the absence or encumbrance of the round window.Certain structural developments, found in several of these species, seem to be secondary in nature, and compensate in some degree for the primary changes. Therefore the sensitivity of these ears, though below average for lizards in general, is not as seriously handicapped as it might otherwise have been. These developments include: (1) an extension of the pars inferior of the extra‐columella to make effective contact with skin and muscle layers, (2) the strategic location of air spaces to increase the mobility of these tissue layers, and (3) the use of reëntrant fluid pathways to replace the round window in the mobilization of cochlear fluids.Despite the changes in the middle ear mechanism in these lizards, there is evidence that their cochlear structures remain fully functional, and that the ear as a whole, although handicapped, continues as a serviceable instrument in the perception of sounds.
Glutamine synthetase in the avian diencephalon
Authors: Piddington Ronald 
Published: June 2005

AbstractGlutamine synthetase (GS) activities are high in the nucleus rotundus of the avian diencephalon in late embryos and hatched chicks. The nucleus rotundus is known to be one component of a visual pathway in birds involving also the neural retina, the optic tectum and the cerebral ectostriatum. Since previous studies have shown that the retina, tectum and ectostriatum have high GS activities as well, the enzyme is considered to be clearly associated in some measure, although not exclusively, with processes subserving vision. Some of the possible normal functions for GS at specific neural sites are discussed.Hydrocortisone promotes GS levels in vitro in the embryonic diencephalon, just as GS activities are increased with this steroid in cultures of embryonic retina, tectum and cerebrum. The effects of steroid on GS in the diencephalon appear to be general and not restricted to the nucleus rotundus or the visual pathway.
Estrogen and brood pouch formation in the marsupial frog, Gastrotheca riobambae
Authors: Jones Richard E. , Gerrard Althea M. , Roth Jan J. 
Published: June 2005

AbstractImmature female Gastrotheca riobambae were treated with either 1 μg or 10 μg estradiol daily for 24 days. Both estrogen dosages elicited formation of the brood pouch, a dorsal integumentary structure which contains eggs or larvae during the breeding season. A decrease or loss of epidermal keratin, dermal chromatophore units and dermal poison glands occurred during both normal and estrogen‐induced pouch formation. Also, pouch skin exhibited dermal hypervascularity and connective tissue hyperplasia. The epidermis lining the pouch lumen possessed crypts. The importance of these changes is discussed in relation to pouch function.
Squid nidamental gland extract: Isolation of a factor inhibiting ciliary activity
Authors: Atkinson Burr G. 
Published: June 2005

AbstractA component of the egg string jelly of Loligo pealei inhibits ciliary activity in ciliated cells, thereby immobilizing a variety of swimming ciliated organisms. This report establishes the nidamental gland as a source of both the egg jelly sheath and the ciliary immobilizing factor. Methods are described for preparing crude and purified fractions of the immobilizing factor from the nidamental gland.
Response of tail fin of Proteus anguinus to thyroxine
Authors: Švob M. , Musafija A. , Frank F. , Durovic N. , Švob T. , Čuˇković S. , Hlaˇa D. 
Published: June 2005

AbstractDiscs prepared from dorsal tail fins of Proteus anguinus Laur. were immersed in a solution of thyroxine in Hank's medium. The tail tissues did not regress under the influence of thyroxine although the concentration of hormone was 100 ppb. Thyroid hormones synthesis was investigated in Proteus through the use of I125 injected intraperitoneally as sodium iodine. Chromatographically separated fractions of Proteus tissues, compared with known standards, indicate synthesis of thyroxine, triiodothyronine, and their precursors mono‐ and diiodotyrosone. It is concluded that the permanent neoteny of Proteus is due to loss of tissue sensitivity to thyroxine.
Glucosamine HCl, hydroxyproline and developmental homeostasis in Drosophila melanogaster
Authors: Rapport Ellen W. 
Published: June 2005

AbstractA new cryptocephal (crc) phenocopy agent is described for Drosophila melanogaster. The morphogenetic action of this agent, hydroxyproline (OHP) is compared to that of another crc phenocopy agent, glucosamine HCI (GA). The sensitive period for OHP lasts somewhat longer than that of GA. A comparison of the effect of GA and OHP on two strains of Drosophila showed that a relatively high strain sensitivity to one agent could be accompanied by a low response to the other. It is concluded that the developmental buffering of the agents is controlled by different genes.
Non‐budding strains of hydra: Isolation from sexual crosses and developmental regulation of form
Authors: Moore Linda B. , Campbell Richard D. 
Published: June 2005

AbstractNew strains of hydra were obtained from sexual crosses; 15% of these strains exhibited impaired or no budding. Altered tentacle number, regeneration, size and form almost always accompanied this non‐budding trait. Strains selected for deficient budding activities were also more variable in morphology than are normal hydra.Two developmental traits were studied in the non‐budding animals; regenerative ability and the formation and control of supernumerary tentacles. The regeneration patterns of non‐budding hydra vary with the size of the piece of regenerating tissue. Column segments greater than 3 mm in length regenerate hydranths at all cut surfaces, whereas pieces less than 1 mm long usually regenerate bases at proximal surfaces, as do normal animals. When polyps grow abnormally long, they form supernumerary tentacles. Formation of these tentacles seems to be normally suppressed by a nearby hydranth. Supernumerary tentacle formation can be suppressed even in long, non‐budding hydra, by implants of hypostomal or subhypostomal tissue.The non‐budding hydra phenotype appears to result from developmental lesions spread throughout the polyp body. Budding is one of the primary aspects of development which is affected, and a lack of budding leads to increased animal size. This in turn results in many pleiotropic effects including supernumerary tentacle formation and altered regeneration patterns.
The effects of anoxia on isozyme patterns and ultrastructure of cultured human fibroblasts
Authors: Henderson Nanine S. 
Published: June 2005

AbstractNumerous studies with lower eukaryotes such as yeast and Neurospora have shown that mitochondrial morphology and enzyme levels change markedly in response to changes in oxygen tension. Several studies with mammalian cells in culture have indicated that these cells also respond to low oxygen with changes in the levels of certain enzymes. In this study gel electrophoretic analysis of enzymes and electron microscopic analysis of cell organelle morphology were used to study the effects of anaerobic conditions on cultured human embryo fibroblasts. Lactate dehydrogenase showed a marked shift from LDH‐1 toward LDH‐5 as has been previously described. Isocitrate dehydrogenase, NAD‐malate dehydrogenase, and NADP‐malate dehydrogenase all have been shown to exist as separate supernatant and mitochondrial isozymes. However, none of these enzymes showed extensive changes in isozyme patterns in response to anaerobiosis. Electron microscopic examination of cell cultures revealed striking changes in mitochondrial structure. Aerobically grown cells have well‐developed, elongated mitochondria with numerous well‐defined cristae and an electron‐dense matrix. In cells cultured anaerobically the mitochondria show degenerative changes. They are more rounded, have few and poorly defined cristae, and the matrix is more electronlucent. These studies indicate that, as in lower eukaryotes, the mitochondria of cultured human cells also respond morphologically and biochemically to changes in oxygen tension.
Factors influencing molting in the crayfish Procambarus clarki
Authors: Bittner George D. , Kopanda Richard 
Published: June 2005

AbstractMolting frequency is increased and intermolt period is decreased by autotomizing the chelipeds and/or walking legs of crayfish (Procambarus clarki) kept under constant environmental conditions. The increase in molting frequency cannot be explained by a loss of body mass since other operations which produced specific tissue damage to nerve or muscle fibers resulted in little or no loss of body mass yet these operations significantly increased molting frequency. Other factors associated with autotomy or nerve and muscle damage such as exoskeletal damage or loss of hemolymph have much less effect on molting frequency and immobilization actually decreases molting frequency. The molting responses to autotomy, muscle or nerve damage, immobilization, and overcrowding appear to be adaptively advantageous.
Analysis of the crowding effect in Rana pipiens tadpoles
Authors: Gromko Mark H. , Mason Francene S. , Smith‐Gill Sandra J. 
Published: June 2005

AbstractRana pipiens tadpoles were grown at four densities in each of three series. Retardation due to crowding was seen despite the presence or absence of feces. Statistical analysis shows retardation due to crowding to be a function of effective density, possibly mediated by behavioral or social factors, more importantly than by diffusible products of the tadpoles. Although previous work has assumed the growth‐inhibiting factors of “conditioned water” (water occupied by a population of tadpoles) to be identical with the cause of the crowding effect, we have found that the crowding effect operates relatively independently of these growth‐inhibiting factors.
The role of hydroplasmic pressure in stolonic growth movements in the hydroid, Bougainvillia
Authors: Wyttenbach Charles R. 
Published: June 2005

AbstractThe effects of intrastolonic pressure on growth activity of the stolon have been ascertained by simultaneously observing the direction of hydroplasmic flow and movements of the stolon tip at close time intervals over many consecutive growth cycles. During each growth cycle (4.4–5.8 minutes long) the tip passes through three distinct stages of inherent retractile potential and associated responsiveness to hydroplasmic pressure. (1) Beginning abruptly at the crest, it displays a strong retractile propensity: low pressure (from proximal flow) elicits a retraction of up to 5.5 μ per 0.2 minute, until the onset of distal flow (increasing pressure) causes it to immediately re‐extend. Thus the depth of retraction is directly determined by the degree and duration of low pressure following the crest. (2) After 1.8–2.0 minutes this retractile tendency becomes suddenly diminished. The tip, if still retracted, now re‐extends regardless of the intrastolonic pressure, and proximal flow during the middle third of the cycle causes only a delayed and shallow retraction to define an intermediate peak. (3) During the final third of the cycle the tip is nonresponsive to hydroplasmic pressure: even under circumstances of lowest pressure, it extends forward to a new crest. It is suggested that this varying retractile capacity may be associated with the pattern of changing thickness of the epidermal layer at the stolon tip.Certain features of the hydroplasmic flow and stolon growth cycles appear to be interrelated, most notably the consistent cessation of proximal flow in relation to a crest or trough. Thus some degree of control seems likely between the stolon tip and the contractile zone responsible for flow.
Inductive role of the nerve cord in regeneration of isolated postpharyngeal body sections of Dugesia dorotocephala
Authors: Sperry Pamela J. , Ansevin Krystyna D. , Tittel Frank K. 
Published: June 2005

AbstractLateral cordless fragments isolated from the postpharyngeal section of Dugesia dorotocephala formed a large normal head at a 90° angle to the original antero‐posterior polarity; postcerebrally, only a hump of undifferentiated tissue developed. This “head‐hump” pattern, and also other types observed in previous studies of lateral fragments, were attributed to the absence of the nerve cord. In order to confirm the inductive role of the nerve cord and to eliminate the possibility that the “head‐hump syndrome” was due to the relative proportions of other tissues besides nerve, body fragments of two experimental groups were observed: (1) the five types of fragments which had no nerve cord but had varying proportions of other tissues present formed primarily “head‐hump” types of regenerates. (2) Almost all fragments which had varying amounts of nerve cord present but the same proportions of other tissues formed regenerates of normal body proportions. Therefore, the absence of the nerve cord does determine the “head‐hump syndrome”.Isolated postpharyngeal half segments containing one nerve cord were allowed to regenerate for varying periods of time before the lateral cordless fragment was isolated. The number of “head‐hump” regenerates from lateral fragments isolated after a one‐day or longer contact with the nerve cord gradually decreased, and the number of regenerates with incomplete head development or which were more elongated postcerebrally increased. These results indicate that the nerve cord acts gradually to determine the differentiation of specific tissues rather than rapidly to determine the overall body plan.
A serologic comparison of bat complements
Authors: Hatten Betty A. , Lutskus Joseph H. , Sulkin S. Edward 
Published: June 2005

AbstractComplement levels of four species of bats were much lower than in guinea pigs when measured by immune hemolysis, bactericidal and immune adherence procedures. Serum pools from three species of Microchiroptera showed somewhat higher levels of complement activity by the immune hemolysis procedure than the megachiropteran species, but not by the immune adherence procedure. Kinetic studies indicated that activities of P. vampyrus and E. fuscus complements were similarly affected by changes in ionic strength of the buffer, but not by changes in pH or in concentrations of divalent ions (Ca++ and Mg++). Eptesicus species of bat complement also gave maximum rates of lysis over a wider range of incubation temperatures than did P. vampyrus and guinea pig complements. Guinea pig complement mediated lysis equally well with rabbit, guinea pig, and bat antibodies. E. fuscus complement showed maximum lytic activity with guinea pig and rabbit antibodies, and P. vampyrus complement with guinea pig antibodies. Minimal lysis occurred when mammalian complements and antibodies were combined with chicken antibodies and complement, respectively. Functionally purified C1 components of guinea pig, chicken, and P. vampyrus and E. fuscus bat complements mediated immune lysis with guinea pig C2–9, but demonstrated little lytic activity in the presence of E. fuscus and chicken C2–9. No significant immunologic correspondence was shown between any of the four species of C1 components by immunodiffusion or turbidimetric procedures. Similar patterns of naturally occurring hemolytic activity present in P. vampyrus and E. fuscus sera for erythrocytes from a wide variety of animals were distinct from patterns obtained with guinea pig and chicken sera. Occurrence of agglutination with some species of cells in addition to or in the absence of hemolysis, however, suggested variations in the specificity of these species of complement for different cell surfaces.
Molecular basis for multiple forms of LDH‐X
Authors: Goldberg Erwin 
Published: June 2005

AbstractThe guinea pig has three molecular species of LDH‐X which are inhibited by antiserum directed against the C subunit. Only two of these are selectively inhibited by anti‐A polypeptide antiserum. Heterotetramers produced by in vitro dissociation and recombination of isozymes and containing B‐C subunit combinations are selectively inhibited only by the anti‐C antiserum. Therefore, the subunit composition of these multiple forms of LDH‐X are: CCCC; CCCA; CCAA. Similarly, rat testes contain two forms of LDH‐X which can be described as CCCC and CCCA tetramers.
Germination of the statoblasts of a freshwater bryozoan, Pectinatella gelatinosa
Authors: Mukai Hideo 
Published: June 2005

AbstractPectinatella gelatinosa has only one generation of statoblasts a year. The statoblasts are dormant when they are formed in summer. When they were kept in water under laboratory conditions, dormancy was gradually broken from late autumn to early spring of the following year. No effective means was found to induce germination in the dormant statoblasts. Some substance(s) which inhibits the germination of statoblasts, hence called blastostasin, was demonstrated in the water in which statoblasts had been stored for a long period. The optimum temperature for germination is about 25°C. Light is an essential factor but is needed for only the initial phase of germination. Prolonged periods of illumination with strong light are inhibitory. Visible light with wavelengths longer than green is effective for germination. Undried statoblasts remained viable for more than three years. Some germination was also obtained from statoblasts dried for 20 months. Undried statoblasts can resist prolonged periods of freezing but are very sensitive to high temperature.It is suggested that the effectiveness of critical experimental factors varies with the previous history of statoblasts. Various unfavorable, but not lethal, treatments resulted in temporary loss of germinability and brought the statoblasts into a resting state, for which the term “induced dormancy” is proposed.
The pattern of morphogenetic control in Chilodonella cucullulus
Authors: Kaczanowska Janina 
Published: June 2005

AbstractThe formation of positional information in cells involves the determination of a geometrical point pattern in a developing system. The translation of genetic information into a spatial pattern is achieved in the unicellular ciliate Chilodonella cucullulus by the two‐dimensional cortical surface which specifies a non‐random distribution of continuously dispersed organelles during the early stage of divisional morphogenesis.The supposed mechanism of positioning operates in a system of spatial coordinates and the system possesses definite reference points and boundaries. One reference point is the site of the oral apparatus. This site, at the stage of early divisional morphogenesis of Chilodonella, acts as a source of positional information specifying the sites of the daughter reference points (centers). These centers specify the sites of differentiation of primordia of the contractile vacuole pores (CVPs). This positional information is regulated by the boundaries of the ventral surface and the topography of the postoral sector. Specified sites of differentiation may be shifted somewhat eventually by structural guidance factors.Inter‐ and intraclonal polymorphism of C. cucullulus suggests that a genie basis for parameters of positioning also exists.The congruence between the model of positional information in multicellular systems (Wolpert, '69, '71) and the analysis of morphogenetic pattern in C. cucullulus is discussed. The cell surface membrane is envisaged as the possible structural site of the mechanism of positioning.