bluuebunny/crossref_metadata_2025_split huggingface dataset:
RNA in Cecropia moth ovaries: Sites of synthesis, transport, and storage
Authors: Pollack Sylvia B. , Telfer William H. 
Published: June 2005

AbstractAzure B staining of Cecropia moth ovarian follicles indicated that the pattern of RNA concentrations characteristic of vitellogenic oocytes is disrupted by a gross redistribution and dispersion, beginning with the final discharge of the cytoplasm of the nurse cells into the oocyte. The cytoplasmic redistribution is largely complete two days later when chorion formation begins, the germinal vesicle breaks down, and the first meiotic spindle forms.At this stage the follicle contains 30 μg of RNA, of which 27 μg are in the follicle cells and only 3 μg in the oocyte itself. The proportionately large amount of follicle cell RNA apparently reflects the synthetic functions of these cells in the formation of yolk and the secretion of chorion. Of the 3 μg in the oocyte, only 1 μg is incorporated into the early embryo while the remainder is found in the yolk cells and serosa.Autoradiography of follicles labeled with H3‐uridine either in vivo or by a “pulsechase” procedure in vitro indicated that, as in other polytrophic insect ovaries, the nurse cell nuclei are the most conspicuous source of oocyte RNA. The germinal vesicle incorporated labeled uridine in previtellogenic follicles. In vitellogenic and later stages neither a germinal vesicle nor a follicle cell contribution to oocyte RNA was detected by the procedures used.
Analysis of histogenesis and regenerative ability of denervated forelimb regenerates of Triturus viridescens
Authors: Powell Jeanne A. 
Published: June 2005

AbstractForelimb blastemata of the adult newt, Triturus viridescens, were denervated at three stages of regeneration and allowed to differentiate in the absence of nerves. Some of these limbs, after developing to specific regenerative ages, were subjected to hand amputations and second denervations. The central question posed was: if the blastema is allowed to differentiate in the absence of nerves, will the resultant limb upon reamputation at a more distal level be capable of initiating renewed regeneration as are aneurogenic larval limbs that have differentiated in the absence of nerves? The older the blastemata at the time of the first denervation, the greater was the incidence of continued morphogenesis. Preliminary histogenesis at the time of the first denervation did not insured continued morphogenesis, nor did complete absence of histogenesis prevent further development. Cartilage elements and muscle differentiated in nerveless regenerates, but both tissues lagged in development compared to those of the contralateral innervated limb. Muscle was reduced in amount, and some evidence indicated that it underwent degenerative changes if the nerveless state was maintained. None of the completely nerve‐free regenerates was able to reinitiate regeneration. Thus blastemal cells were not able to return to the embryonic level of independence of nerve supply under the conditions of the experiment.
Effects of 6‐azauridine on the embryonic cells of Xenopus laevis, with special reference to nucleolar ultrastructure
Authors: Sameshima M. , Shiokawa K. 
Published: June 2005

AbstractEffects of 6‐azauridine on isolated embryonic cells of Xenopus laevis were examined electronmicroscopically. It has been revealed that shortly after the treatment, when the rate of RNA synthesis became reduced, a unique ultrastrutural change occurred in the nucleoli: granular component greatly decreased in amount, while fibrous component retained a rather normal, though somewhat coalesced, net‐work structure. Four to six hours later, when inhibition in the syntheses of protein and DNA became apparent, the nuclear chromatin condensed and the nucleoli became a small round mass which consisted of fibrous component alone in some cells. Finally at the tenth hour, most cells showed pycnotic feature and the nucleoli were fragmented and frequently disappeared. At this time, endoplasmic reticulum and mitochondria were also deformed and decreased in number. The significance of the nucleolar alteration observed has been discussed.
Changes in epididymal spermatozoa and in the testes of rabbits after experimental cryptorchidism
Authors: Igboeli G. , Foote R. H. 
Published: June 2005

AbstractSurgical cryptorchidism was induced in sexually mature rabbits by a scrotal incision approach or an abdominal approach, and the effects were observed for the next 14 days. Various combinations of ligatures on the corpus epididymidis and ductus deferens were employed to compare effects with and without restricted sperm movement.Neither cryptorchidism nor epididymal ligatures reduced libido. However, ejaculate volume significantly decreased after 14 days of cryptorchidism (P < 0.05), and this may have resulted from a reduction in contributions by the epididymis as indicated by oligospermia.Damage due to cryptorchidism was significantly more severe on sperm in the caput than in the cauda epididymidis. Four days of cryptorchidism caused an increase in percent of abnormal spermatozoa at all levels of the epididymis. It did not alter the percent of unstained sperm or fertility of sperm in the cauda epididymidis. Thus, uncapacitated sperm in the male at body temperature retain their fertilizing potential for considerably longer periods than capacitated sperm do in the female. Cryptorchidism for seven or more days resulted essentially in a complete loss of fertility of cauda sperm. Caput sperm usually were infertile initially, and after retention by ligation or after the elevation of temperature by cryptorchidism.Testicular alterations were detected after one or more days of cryptorchidism, characterized by cellular sloughing, giant cells, absence of tubules in stage 8 and testicular and tubular shrinkage. Ligatures on the corpus also caused fluid and sperm accumulation and interfered with spermatogenesis. This fluid accumulation was associated with a significant increase in caput epididymal weights (P < 0.05).
The mesoglea of hydra. I. Physical and histochemical properties
Authors: Hausman Robert E. , Burnett Allison L. 
Published: June 2005

AbstractThe mesoglea of Hydra serves both as a skeleton and as a substratum for cell migration. These functions are made possible in Hydra pseudoligactis by a system of fibers that run along the body column, parallel to the oral‐aboral axis, and perpendicular to the oral‐aboral axis. The fibers are either a mucoprotein or a close spatial arrangement of protein and polysaccharide. They are 0.3 μ in diameter and contain an elastin‐like and collagen‐like protein.Spaced along the fibers are acid mucopolysaccharide‐like particles, 0.7 μ in diameter, which appear to serve a structural or supportive function. Between the fibers are 2.4 μ diameter holes for extension of epithelial cell processes. The remainder of the mesoglea consists of an amorphous gel with a collagen matrix.The physical arrangement of the fibers allows the normal movements of hydra and could also control the direction of cell migration. The arrangement of fibers may be a dynamic system under the control of an enzyme.
Hormonal dependence of tail regeneration in the lizard Anolis carolinensis
Authors: Licht Paul , Howe Nathan R. 
Published: June 2005

AbstractRemoval of the pars distalis several days before the amputation of the tail in Anolis carolinensis delays blastema formation and virtually abolishes tail regeneration. Hypophysectomy on, or several days after, tail amputation does not delay blastema formation but tail growth is largely abolished. If lizards are hypophysectomized after the blastema has formed and the tail has begun to elongate, the rate of tail regeneration is greatly reduced within a few days.Injection of a combination of adenohypophysial hormones (growth hormone, prolactin, gonadotropin, and thyrotropin) restored tail regeneration to near normal levels in hypophysectomized lizards.A quantitative relationship was evident between the amount of pars distalis removed and the rate of tail regeneration. However, there was no apparent relationship between the region of the gland removed and regeneration, indicating that tail regeneration is probably dependent on a combination of several pituitary hormones.
Some aspects of tail regeneration in the lizard, Anolis carolinensis. I. A description based on histology and autoradiography.,
Authors: Cox Prentiss G. 
Published: June 2005

AbstractThe histology of the tail and its autotomy planes in Anolis carolinensis follows the same basic plan as that described for other lizards. Variations in detail which are of importance to the present paper are described. The normal regeneration process was studied using histologic and autoradiographic techniques. These studies suggest: (1) that the muscle makes little if any contribution to the regenerate, (2) that the source of cells for the regenerate is primarily from the various connective tissue elements and (3) that the tail has no apical accumulation blastema. It is proposed that the term blastema as applied in amphibian limb regeneration cannot be applied in lizard tail regeneration. The growth of a normal regenerate results from extensive interstitial growth in the differentiating tissues and from subapical growth in the less differentiated areas of these tissues.
Staining of intercellular material in reaggregating chick liver and cartilage cells
Authors: Khan Talat , Overton Jane 
Published: June 2005

AbstractLanthanum has been used to study the immediate cellular environement in reaggregating liver and cartilage cells and in mixtures of the two cell types in order to permit visualization of intercellular material by electron microscopy. Lanthanum staining material was absent from the cell surface in freshly isolated cells but was present between cells in all stages of reassociation. The stained material characteristic of cartilage and liver cells differed. Thus in mixed reaggregates it can be demonstrated that from early stages in the process cells are exposed to different sorts of cell products. Enzymatic treatment of reaggregates suggested that lanthanum may stain mucopolysaccharide.
Age‐dependent changes in alcohol dehydrogenase in Drosophila
Authors: Dunn G. R. , Wilson Thomas G. , Jacobson K. Bruce 
Published: June 2005

AbstractDrosophila melanogaster alcohol dehydrogenase undergoes changes both in specific activity and in the isozyme forms during the course of development of larvae and adults. Specific activity is high in the larva, low in the pupa, high again in the young imago, and declines gradually thereafter. One of the five forms of alcohol dehydrogenase, ADH2, appears only for one day immediately preceding pupation and is present from days 1–12 of adult life; ADH3 and ADH5 are present at all ages. These results are interpreted to mean: (1) alcohol dehydrogenase is physiologically regulated, (2) isozyme forms can be produced and removed and (3) a mechanism presumbly exists to do this.
The influence of a head graft on regeneration of the isolated postpharyngeal body section of Dugesia tigrina
Authors: Ansevin Krystyna D. 
Published: June 2005

AbstractThe influence on regeneration of a reversed head graft attached to the posterior end of the isolated postpharyngeal section of Dugesia tigrina was studied following removal of the graft after varying periods of time. After section‐graft association for as long as three days, the predominant effect of the graft was inhibitive: regeneration of the head was blocked first, position or reconstruction of the pharynx next, and elongation of the body arrested last. This appears to indicate the sequence of determinations of these structures and the times when they occur in normal morphallaxis of the isolated postpharyngeal section. Four days of section‐graft association appeared sufficient for the grafts' own inductions to occur in the section. Longer associations resulted in gradual, and ultimately complete reversal of polarity of the postpharyngeal section.
An ultrastructural study of lens invagination in the mouse
Authors: Wrenn Joan T. , Wessells Norman K. 
Published: June 2005

AbstractEarly lenses of mouse embryos were studied with the electron microscope to determine whether their cells contain organelles that can be causally related to the invagination of the lens placode. The cells of the placode and early lens cup are joined at their apical ends by junctional complexes. At the level of the zonula adhaerens, favorable sections show cytoplasmic filaments, 35 Å to 50 Å wide, arranged about the apex of a cell. Groups of filaments appear to originate on or near the plasma membrane and then to extend across the cytoplasm, parallel to the apical cell surface, to terminate on or near the plasma membrane some distance away. They are nearly always straight; in contrast, nearby lateral and apical cell membranes are twisted into irregular folds and projections.We present a model to explain lens invagination in which the filaments are considered to be contractile. On the basis of their location in the cells and their presumed function, these organelles are proposed to be a major component in the mechanism that leads to early morphogenesis of the lens.
Activation of DNA replication in the iris epithelium by lens removal
Authors: Yamada Tuneo , Roesel Marion E. 
Published: June 2005

AbstractThe pattern of DNA replication during the initial stages of Wolffian lens regeneration has been examined by an autoradiographic study of tritiated thymidine uptake in zero to five‐day regenerates (Triturus viridescens). Scanning of complete sets of serial sections for each iris revealed the absence of labeled cells in normal, one‐, and two‐day iris epithelia, and a very infrequent occurrence of labeled iris epithelial cells in some three‐day regenerates. After this stage, cell labeling is seen in all iris epithelia. Cell labeling frequency increases markedly by four days, and is at a very high level in five‐day regenerates.Further data indicate that labeling begins in the dorsal sector of the iris epithelium. By five days after lens removal, however, it reaches similar levels in dorsal, lateral, and ventral sectors. Thus, DNA replication is induced throughout the iris epithelium after lens removal, even though the lateral and ventral sectors of the iris epithelium do not participate in actual lens formation.Comparison between the outer and inner laminae of the iris epithelium shows that during all stages studied the great majority of labeled cells are in the inner lamina.
Effect of blinding on reproductive and pelage cycles in the ferret
Authors: Rust Charles C. , Shackelford Richard M. 
Published: June 2005

AbstractThe effect of blinding on reproductive and pelage cycles in ferrets held outdoors under natural environmental conditions was investigated from October, 1966, to March, 1969. Blind female and intact male and female ferrets underwent the normal seasonal changes during this period. They became reproductively active and underwent the spring molt in March and April and became reproductively quiescent, molted and grew the dense winter pelage in September and October. Blind male ferrets exhibited a prolonged reproductive period which began in March and April, 1967, and extended through December. An incomplete pelage change and partial testicular regression occurred in most blind males in January and February, 1968. The same sequence of reproductive and coat changes was observed the following year. Blind and intact female ferrets mated to blind males bore normal litters.
Synchronous oogenesis in Engystomops pustulosus, a neotropic anuran suitable for laboratory studies: Localization in the embryo of RNA synthesized at the lampbrush stage
Authors: Davidson Eric H. , Hough Barbara R. 
Published: June 2005

AbstractAn investigation of several tropical frogs was undertaken in order to find species in which synchronous oogenesis takes place, so that the RNA synthesized at the lampbrush stage could be labelled and followed through early development. The reproductive cycle of Engystomops pustulosus was found to include both synchronous and asynchronous phases. Laboratory maintenance and induction of synchronous oogenesis in this organism are described. By using toads carrying out synchronous oogenesis, RNA synthesized during the lampbrush stage was shown to be retained through gastrulation. The pattern of new RNA synthesis in the embryo resembles that in other anurans. Radioautographs suggest that the distribution in the embryo of maternal RNA synthesized at the lampbrush stage is distinct from that of RNA newly synthesized by the embryo; the possible implications of these observations are discussed.
Lactate dehydrogenase isozymes of Pacific hake (Merluccius productus)
Authors: Utter F. M. , Hodgins H. O. 
Published: June 2005

AbstractThe lactate dehydrogenase isozymes of Pacific hake (Merluccius productus) are described. Evidence from molecular weight estimations and subunit recombination tests indicate that these isozymes have physicochemical properties similar to those of higher vertebrates. The predominant isozymes in most tissues appear to be composed of subunits coded at two loci. These subunits and loci were designated as A and B because of phenotypic similarities to isozymes coded by the LDH A and B loci of higher vertebrates; no attempts were made, however, to establish homologies between isozymes of Pacific hake and those of higher vertebrates. The predominant isozyme in extracts of skeletal muscle appears to be independent of those composed of A and B subunits and may reflect a third LDH locus in Pacific hake. In contrast to many species of teleost fish, no unique LDH isozymes were found in the eye.Isozyme phenotypes reflecting two alleles, A and A′, were observed at the A locus. The frequency of the A′ allele was 0.01 in fish taken from the Pacific Ocean off the coasts of California, Oregon, and Washington and 0.25 in those from Puget Sound, Wash., it appears that the two populations are noninterbreeding. Gene‐frequency analyses of samples taken in various areas of Puget Sound indicate that the Puget Sound hake consist of a single breeding population.
Nucleic acid deficiency in the prothanic homozygous mutant of creeper fowl
Authors: Wallace H. , Clyman R. I. , Pierro L. P. 
Published: June 2005

AbstractProthanic Cp/Cp chick embryos synthesize ribosomal RNA to a lesser extent than control embryos, but incorporate radioactive uridine into RNA of a higher specific activity. Prothanic embryos contain less DNA, RNA and protein than control embryos at 72 hours. The deficiency of DNA is found equally in embryonic and extra‐embryonic Cp/Cp tissues. The deficiencies of RNA and protein are more marked in Cp/Cp embryos than in Cp/Cp extra‐embryonic tissue. These results, and similar observations on phenocopies, are considered to imply that the primary developmental defect of prothanic embryos concerns the extra‐embryonic circulatory system.
The fine structural organization of the sea nettle fishing tentacle
Authors: Burnett J. W. , Sutton J. S. 
Published: June 2005

AbstractThe fishing tentacle of the sea nettle (Chrysaora quinquecirrha) has four basic layers: an outermost epithelial layer, a muscle cell layer, a core of mesoglea and an innermost epithelial layer. The outermost epithelium contains three different cell types: (1) supporting cells, (2) nematocytes and (3) mucous cells. Apical cellular processes of smooth muscle fibers extend into the outermost epithelial layer whereas basal processes penetrate the mesoglea. The mesoglea contains randomly oriented fibrils (60–70 Å in diameter). Inner epithelial cells vary in morphology. Some cells contain mostly phagocytotic vacuoles while other cells have an abundance of rough surfaced endoplasmic reticulum.
Effect of pituitary hormones, androgens, and corticosteroids on the seminal vesicles of the castrate catfish, Heteropneustes fossilis (Bloch)
Authors: Nayyar S. K. , Sundararaj Bangalore I. 
Published: June 2005

AbstractΔ5‐3β‐hydroxysteroid dehydrogenase activity (Δ5‐3β‐HSD) has been studied in the interrenal glands and the seminal vesicles of intact and castrate male catfish. The intensity of the enzyme reaction is about equal in the seminal vesicles of both groups, whereas the intensity of enzyme reaction in the cortical cells is more pronounced in the castrate than in the intact male.The responses of the interrenal glands and the regressed seminal vesicles of the castrate catfish in the postspawning period to exogenous luteinizing hormone (LH), Δ4‐androstenedione (Δ4‐androst.), desoxycorticosterone acetate (DCA) and hydrocortisone acetate (HA) (experiment 2), and the effect of the LH, Δ4‐androst., DCA and HA, and prolactin (LtH) and growth hormone (STH), singly or in combination on the regressed seminal vesicles of the castrate catfish (experiment 3) have also been studied. The data indicate that both LH and Δ4‐androst. induce secretory activity in the seminal vesicles but they appear to act through different routes. Since LH brings about an increase in the nuclear diameters in cortical cells and Δ4‐androst. does not, it is felt that LH acts through the cortical cells of the interrenal glands while Δ4‐androst. acts directly on the seminal vesicles. Further, Δ4‐androst. can synergize with LtH and STH in inducing secretory activity in the seminal vesicles, whereas DCA and HA do not. These results, coupled with the fact that Δ5‐3β‐HSD activity is more marked in the cortical cells of the castrate than in the intact catfish, strongly suggest that following castration, the resulting high titers of gonadotrophin act on the interrenal cortical cells to produce androgens which, in turn, induce hyperactivity in the seminal vesicles.
The effect of actinomycin D on nucleolar formation in early Xenopus laevis gastrulae
Authors: Sameshima M. , Shiokawa K. , Kawakami I. 
Published: June 2005

AbstractElectron microscopic examinations revealed drastic effects of actinomycin D on nucleolar formation in isolated cells of Xenopus laevis embryos. The nucleoli in newly isolated cells of early gastrulae were composed solely of a fibrous component. After culture for two to five hours in complete Stearns' solution without the antibiotic, a granular component appeared among the fibrous components in most of the nucleoli, which showed more elaborated structures. On the other hand, after being cultured for two hours in the presence of actinomycin D (l r/ml), by which inhibition of DNA synthesis was effected, all the nucleoli examined remained as spherical masses composed of fibrous component alone, lacking granular component. After five hours' treatment, inhibition of the synthesis of protein and DNA became biochemically detectable, and ultrastructural changes were observed in both the nucleoplasm and the cytoplasm: that is, fragmentation of nucleoli, condensation of chromatins and deformation of mitochondria. Relationships between the formation of nucleolar components and the RNA synthesis in amphibian embryogenesis are discussed.
Spectral sensitivities of color receptors in the compound eye of the cockroach Periplaneta
Authors: Mote Michael I. , Goldsmith Timothy H. 
Published: June 2005

AbstractIntracellular recording from single retinular cells of a white eye mutant of the cockroach Periplaneta americana stimulated between 316 and 704 nm reveals the presence of two classes of cells. In the dorsal part of the eye they are present in approximately equal numbers. Both have resting potentials of about 40 mv; neither responds with spikes.Ultraviolet receptors are maximally responsive at 365 nm (λmax); sensitivity falls steadily at longer wavelengths and is down two log units at 440 nm. The membrane responses of ultraviolet receptors usually consist of a large graded transient which can completely depolarize the cell, followed by a smaller and slower plateau of depolarization which lasts as long as the stimulus.Green receptors have λmax at about 507 nm. A tail of sensitivity extends through the violet and near ultraviolet, but sensitivity falls steadily to the long wavelength side of the λmax, and is down two log units at 615 nm. The membrane responses typically consist of a graded transient and lack the later plateau.