bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations on nuclear differentiation in Ascaris
Authors: Swartz Frank J. , Henry Mary , Floyd Alton 
Published: June 2005

AbstractA microdensitometric survey of the DNA content of adult Ascaris nuclei was undertaken to determine the relationship between these values and those expected as a consequence of somatic chromatin diminution. The species diploid value was derived from measurements of Feulgen stained sperm nuclei and unreduced primary oocytes. The somatic DNA values, expected to be hypodiploid if unaltered following diminution, fall into three groups. The first, the intestinal nuclei, are closest of all positively staining nuclei to the anticipated values but are nevertheless in the tetraploid range. A second group of somatic cells, constituting the uterine epithelium, pharyngeal glands and excretory cell present nuclei with quantities of DNA suggestive of high degrees of polyploidy. A “polyploid” gradient exists within the nuclei of the uterine epithelium. Values equivalent to 150‐ploid are found in the posterior half of the uterus, becoming progressively lower toward both ends. The gradient corresponds closely to the known protein synthetic activity of the epithelium. Nuclei of the pharyngeal glands and excretory cell, among the largest nuclei reported, stain distinctly with the Feulgen reaction but their degree of “polyloidy” has not been estimated. On occasion, the excretory nucleus has been noted to be Feulgen negative.The third group of nuclei include those of the somatic muscle and ganglia. By all of the cytological tests for DNA applied (Feulgen staining with standard and fluorescent Schiff reagent, acridine orange and methyl green staining) the muscle nuclei are negative; however, they contain considerable amounts of RNA. Some of the neuron nuclei are negative while others show a faint membrane‐associated staining. The Feulgen‐negative nuclei of the adult most likely represent those which remain in the originally diminished condition.
Detection of qualitative differences between the RNA of livers and kidneys of adult chickens and a temporal and regional study of liver RNA in chick embryos
Authors: Miyagi M. , Kohl D. , Flickinger R. A. 
Published: June 2005

AbstractRNA preparations from livers and kidneys of adult chickens were qualitatively distinguished by DNA‐RNA hybridizations involving double saturation experiments. This technique was used to study the temporal and regional synthesis of liver‐like RNA in the developing chicken embryo. It was found that the amount of liver‐like RNA in the embryo increases from two and one half days to three and one half days of development. Furthermore, this liver‐like RNA was found in greater amounts in the areas of three and one half day embryos containing the differentiating liver rudiment.
Differentiation of chromatophorotropins from the prawn, Palaemonetes vulgaris, and the fiddler crab, Uca pugilator
Authors: Fingerman Milton , Couch Ernest F. 
Published: June 2005

AbstractThe fiddler crab, Uca pugilator, and the prawn, Palaemonetes vulgaris, produce chromatophorotropins that disperse the red pigment in both species, concentrate the red pigment in both species, and disperse the melanin of the fiddler crab. The prawn does not have melanophores. However, the hormone obtained from organs of either the prawn or the crab that concentrates the pigment in the erythrophores of the prawn is different from the hormone present in the same extract which has the same physiological effect on the erythrophores of the crab. The identical conclusion was arrived at when the hormonal control of red pigment dispersion was considered. Furthermore, it was evident that dispersion of the red pigment and melanin dispersion in the fiddler crab were caused by different substances, when extracts of organs from Palaemonetes vulgaris as well as from Uca pugilator were tested.
Age‐dependent intraclonal conjugation in Euplotes crassus
Authors: Heckmann Klaus 
Published: June 2005

AbstractIn Euplotes crassus each of the five different mating‐types is determined by a different allele at the mating‐type locus. There is complete dominance among these alleles so that in diploid cells only one of them is phenotypically expressed. It was observed that in heterozygous clones expressing only one mating‐type, cells arose after about 500 consecutive fissions which expressed another mating‐type. This observation led to the finding that in E. crassus, late in the life history of a clone, a stage is reached in which the dominance relationship among the mating‐type alleles is abolished. A cell heterozygous at the mating‐type locus is at that stage no longer stable with respect to mating‐type transmission, its mitotic progeny expresses either one of their two mating‐type alleles and are therefore able to conjugate with each other, as soon as different mating‐types are expressed. It is further shown that intraclonal conjugation inaugurates new life cycles so that mating‐type instability seems to serve the same function as autogamy in other ciliates, i.e., it starts new life cycles for cells which have failed to find interclonal mates.A few heterozygous clones have been found which were not able to enter the stage of mating‐type instability. It is shown that they are genetically related and that they can be interpreted as carrying a dominant mutation which does not allow them to enter the life cycle stage of mating‐type instability.
The development of the electromyogram in chick embryos
Authors: Boëuthius Jöurgen 
Published: June 2005

AbstractElectromyograms (EMG's) of developing chick embryos were recorded with an electrolytically sharpened tungsten electrode and with a concentric unipolar electrode.Earlier observations of the occurrence of movements on the sixth day were confirmed. Before the twelfth day, only small irregular potentials could be obtained from the muscles (amplitude less than 50 μV). After the twelfth day, the amplitude of the action potentials (potentials) increased rapidly. Up to the fifteenth day, the potentials were mainly monophasic (amplitude 150 μV). On the seventeenth day, the amplitude reached about 500 μV and the potential configuration was similar to that of the adult. The duration of the potentials did not change significantly during this period.The EMG activity occurred in bursts. The duration of the bursts from the wing muscles tended to be less than one second whereas in the leg muscles it was generally 2‐5 seconds. This difference in burst duration was systematically studied on six embryos aged 14‐17 days and its functional significance was discussed.To obtain a rough estimate of the maximal firing frequency of the motor units, the “overall frequency” of the potentials was measured. A steep increase in frequency was found between the twelfth and fifteenth day and an interference pattern of the adult type was obtained on the seventeenth day. The temporal correlation between these changes in the EMG pattern and other properties of the developing muscles was discussed.
Actinomycin D: Effect on induced metamorphosis in the Mexican axolotl
Authors: Prahlad K. V. , Delanney L. E. 
Published: June 2005

AbstractActinomycin D was used to inhibit the action of T3 in the induction of metamorphic changes in the Mexican axolotl. Am D was administered before and after (in hours) T3 injection as follows: (1) ‐48; (2) ‐24; (3) ‐8; (4) 0; (5) +24; (6) +48; (7) +72; (8) +120; (9) +168. Five μg Am D administered alone was not lethal. However the majority of the animals injected with T3 and Am D died within 30 to 33 days. All experiments were at 20°. Suppression of metamorphic change was greater in group 2 than 1 and greater in groups 4 and 5 than 6. Group 3 showed maximum inhibitory effects of Am D. Very little inhibition was seen in groups 7 through 9. Gill filament resorption and sloughing of skin could not be inhibited completely in any of the groups. Exophthalmia was seen in all except group 3. Least changes occurred in the main gill rachis and the fins. When Am D was administered to hypophysectomized axolotls eight hours prior to T3 there was complete gill filament resorption before any change was observed in controls. Also skin sloughing and exophthalmia were precocious in Am D and T3 injected hypophysectomized axolotls. The observations above indicate variable responses in the metamorphosing tissues of the axolotl to Am D. Hence utmost caution is necessary in the interpretation of any of the inhibitory effects of Am D at the cellular level.
Histopathology of intersexuality in mosquitoes
Authors: Anderson John F. 
Published: June 2005

AbstractMasculine expressivity in several species of mosquitoes is dependent upon low larval rearing temperatures. At elevated temperatures femininity prevails in both sexual genotypes. This paper is concerned with the histological development of organs of genotypic males of Aedes stimulans (A. stimulans) and ix Aedes aegypti (A. aegypti) before, during and after their determination to a specific sexual form. Intersexuality of homologous and nonhomologous organs was shown to arise in a manner that has not been previously reported in insects. Homologous organs develop similarly in the two sexes up to a critical stage, after which divergent morphogenesis commences. This critical period occurs at an earlier stage of ontogeny in males than it does in females. At elevated temperatures and during their period of plasticity, organs of genotypic males developed in a feminine manner. Determination began approximately at the time of divergent development. If the temperature remained high at this time, organs continued their feminine development, but if the temperature was lowered before feminine specialization, masculinity quickly ensued. Nonhomologous organs that are found only in males were present during ontogeny of larvae which were reared at elevated temperatures. These organs reached a high degree of juvenile masculine specialization during the larval period, but then histolyzed during pupal development. Nonhomologous organs that are present only in females were also studied. Primordia of the median oviduct, spermathecae and related feminine parts were the ones selected. In genotypic males which were reared at high temperatures, the primordia appeared at the same time and developed in the same manner as did those of a normal female. When larvae were reared at elevated temperatures just long enough to activate these primordia and were then exposed to low temperatures, the discs developed into masculine genital appendages of abdominal segment eight.
Tissue specific esterase isozymes of the mouse (Mus musculus)
Authors: Ruddle Frank H. , Harrington Linda 
Published: June 2005

AbstractFor this report, the tissue‐specific esterase isozymes of 35 organs of the mouse, Mus musculus, were studied by means of starch gel electrophoresis. Zymogram patterns of organs from males and females of the inbred strains SJL/J, C57BL/6J, and RF/J were compared. The ensemble of esterase isozymes expressed by each organ is in most instances distinctly unique. Sexual dimorphisms are reported for the submaxillary gland and the kidney. These are believed to be under hormonal control. It is postulated that enzyme differences between the male and female with regard to the submaxillary gland and kidney may be significant in the biosynthesis and/or secretion of pheromones.
Developmental studies of the dipteran salivary gland. IV. Changes in DNA content
Authors: Laufer H. , Rao B. , Nakase Y. 
Published: June 2005

AbstractThe DNA content of the salivary gland was measured by the method of Burton in larvae of Chironomus thummi at four stages of development during the onset of the larval‐pupal metamorphosis. The amount of DNA at first increased in the gland, from 0.28 μg/gland at the mid‐fourth instar to 0.45 μg/gland in the early prepupa. This increase was immediately followed by a significant decrease in the amount of DNA to 0.37 μg/gland in the late prepupa.The loss of DNA is considered to be of major interest since it occurred at a time when chromosomal puffing is observed in some regions of the chromosomes. Puffing reflects gene activity. Furthermore, the loss of DNA was preceded in the early prepupa by an increase in the gland's DNase content. The change in this enzyme represents the first detectable chemical change signaling the onset of glandular metamorphosis and suggests that portions of the polytenic chromosomes are the substrate for this hydrolase. This suggestion is substantiated by the constancy of the cell number within the salivary gland and the loss of nuclear volume in individual gland cells. The destruction of the gland appears to be a self‐regulated programmed event occurring in the course of normal development and seems to be mediated by the control of the enzyme DNase.
Cortical slippage in Tetrahymena
Authors: Nanney D. L. 
Published: June 2005

AbstractTwo strains of Tetrahymena pyriformis manifest similar deviations from the usual pattern of stomatogenesis. Some of the cells develop oral anlagen in the normal manner on the right postoral meridian (meridian 1), but others have oral primordia displaced to the left or (less frequently) to the right by one or more ciliary rows. The other caudal organelles, the cytoprocts and contractile vacuole pores, are displaced in a similar manner. In the course of successive fissions and repeated stomatogenic shifts, the stomatogenic site, and indeed all cortical structures, are expected to completely circumnavigate the cell. These observations support the interpretation that the various kineties are not permanently differentiated with respect to their morphogenetic capacities.
Fine structure of gametes of Nereis limbata (Annelida) before and after interaction
Authors: Fallon John F. , Austin C. R. 
Published: June 2005

AbstractThe acrosome of the Nereis limbata spermatozoon is a vesicular body which is shaped in the form of a double‐walled hollow cone. As such it encloses an axial chamber housin the anterior part of a rod‐like structure which, posteriorly, fits into a deep invagination in the nucleus. When the acrosome undergoes reaction preparatory to and during penetration of the egg envelope, it opens anteriorly, discharging its contents, and the axial chamber, together with its contained rod, is expanded and portruded as the acrosome filament.The chorion of the egg is about 0.7 μ thick, and is traversed completely by microvilli which project at intervals. Numerous broad canals extend about three‐quarters through the chorion. It is by one of these canals that the acrosome filament passes in the initial stages of sperm penetration.The cortex of the egg has a wide zone of densely packed alveoli which contain moderately electron‐dense material, the jelly precursor. Cortical reaction to sperm entry involves fusion between adjacent alveoli and opening up of alveoli onto the cytoplasmic surface of the egg. Released jelly precursor, evidently becoming hydrated, flows into the perivitelline space and thence through the pores in the chorion that accommodate the microvilli (flowing around the microvilli which persist), so as to form a thick layer about the egg.
Pentose phosphate pathway activity of the chick embryo in ovo
Authors: Wenger Eleanor , Wenger Byron S. , Kitos Paul A. 
Published: June 2005

AbstractUsing a novel radio‐respirometer, the relative activity of the pentose phosphate pathway has been determined at various stages of development of the chick embryo, by comparing the recovery of C14O2 from glucose labeled in position one (G‐1) to that from glucose labeled in position six (G‐6). Resiprometry was performed on the intact embryo in ovo using concentrations of glucose within the range found in normal embryonic body fluids. Significantly greater recovery of C14O2 from G‐1 relative to that from G‐6 was obtained at 68–72 hours and again at 6–8 days. These periods correspond in temporal position with previously reported maxima in glucose‐6‐phosphate deydrogenase activity in the brain of the developing chick embryo and are considered to support the interpretation that patterns of the enzyme activity, determined on homogenates in vitro, reflect patterns of activity of the pentose phosphate pathway in ovo.
Diurnal variations of the fattening response to prolactin in the golden topminnow, Fundulus chrysotus
Authors: Lee Richard W. , Meier Albert H. 
Published: June 2005

AbstractFattening was induced in sexually mature golden topminnows, Fundulus chrysotus, by daily injections of prolactin or luteinizing hormone. However, the time of treatment was of fundamental importance. Whereas injectins given during the middle of a 16‐hour photoperiod stimulated an increase in body weight and fat stores, injections given early in the light period caused a loss in body weight and lipid reserves. These results suggest that the phasing of diurnal rhythms of prolactin and/or luteinizing hormone release from the pituitary may be important in regulating the annual cycle of fat stores.Prolactin, alone, did not induce substantial fattening, if any at all, in hypophysectomized topminnows. Accordingly, the necessity for other pituitary factors at the midphotoperiod interval is apparent. In addition, the deoreases in the lipid and dry nonlipid components of hypophysectomized F. chrysotus by prolactin injections, early in the photoperiod or at midday, suggest there is at least one extra‐hypophyseal factor which exhibits a diurnal periodicity affecting the responses to prolactin.
Regeneration of a sensory system: The formation of central connections by normal and transplanted cerci of the house cricket Acheta domesticus
Authors: Edwards John S. , Sahota T. S. 
Published: June 2005

AbstractThe abdominal cerci of the house cricket, Acheta domesticus, regenerate after amputation. Regenerating sensory fibers establish normal functional connection with the giant fiber system in the terminal ganglion.When cercal regenerates were transplanted to the stumps of the mesothoracic legs, a cercus developed instead of the usual leg regenerate. The regenerate cercus sent fibers to the mesothoracic ganglion. Histological and electrophysiological evidence is presented which demonstrates the formation of synaptic contact with elements of the giant fiber system in the ganglion of the segment receiving the graft.It is inferred that regenerating sensory fibers can recognize the central fibers on which they normally terminate, in this case the giant fibers, at some distance from the normal region of synaptic contact. They recognise the cell as a whole rather than a specific synaptic area.
Temporal skin factors influencing the development of melanoblasts in piebald mice
Authors: Mayer Thomas C. 
Published: June 2005

AbstractThe mechanism involved in the development of the pigmentary pattern in piebald (s/s) mouse embryos was investigated through the use of a combination grafting method. Skin from a potentially white spotted area of piebald embryos ranging in age from 11 days to birth was combined with 9‐day neural tubes. Following grafting of the tissues to chick host embryos, melanoblasts migrated from the nerual tube into the developing skin, and the appearance of pigment in the hair follicles and interfollicular epidermis of the grafted skin was determined. Eleven‐day s/s skin produced pigmented hair in only 16% of the cases, and no melanocytes were found in the interfollicular epidermis. By 13 days 79% of the grafts formed pigmented hair while the epidermis remained pigment‐free. Combination grafts recovered from implanting embryonic skin 16 days and older produced pigment regularly both in the hair follicles and the interfollicular epidermis. Contrl grafts of skin only were devoid of pigment in all ages tested.These results indicate that an inhibitor of melanoblast differentiation or survival is present in piebald skin at 11 days of embryonic age. Conditions favorable for melanoblast differentiation appear in s/s skin by 13 days and, by 16 days, melanoblasts undergo differentiation in both the hair follicle and the epidermis. A mechanism of action of piebald during development is proposed.
Lysosomes in the spleen of the chick embryo. I. Description in the normal spleen
Authors: Kimmel Charles B. 
Published: June 2005

AbstractThe spleen of the 19‐day chick embryo is shown to contain large amounts of hydrolytic enzymes active at acid pH (acid phosphatase, acid deoxyribonuclease, acid ribonuclease, cathepsin, aryl‐sulfatase and β‐glucuronidase), which are associated with subcellular particles that have the properties of lysosomes. (1) The enzymes can be sedimented with subcellular fractions which contain particles approximately the size of mitochondria. (2) The enzymes are associated with a band of particles of greater density than mitochondria in sucrose gradients. (3) The activities of the structure‐linked enzymes are latent. (4) The cytochemically demonstrable activity of acid phosphatase is found in discrete regions of the cytoplasm of the spleen cells.The amount of activity increases with developmental age of the embryonic spleen. This finding is correlated with the increase in detectable acid phosphatase‐containing particles. The most marked period of lysosome production is from the twelfth to the sixteenth day of development.Previous investigations have shown that both major types of phagocytic cells, granulocytes and macrophages, differentiate in the embryo spleen. It is known that in the mammal these cells are rich in lysosome. The production of lysosomes in the spleen is correlated with the differentiation of granulocytes, and with the functional development of the spleen as a reticuloendothelial organ.
Developmental disappearance of a fowl red blood cell antigen
Authors: Sanders Bob G. 
Published: June 2005

AbstractRabbit antisera against red blood cells from three‐day‐old chickens, absorbed with adult chicken red blood cells, identify an antigen on the red blood cells of young chickens that is not detectable in adults. The antigen is present on all red blood cells at hatching. Approximately 50 days after hatching, cells with the antigen start to disappear and are completely undetectable by 120 days. Studies aimed at elucidating the mechanism of the developmental antigenic change suggested that the antigen or a component of the antigen is lost during development rather than being coated by a serum component or embedded in the red blood cell membrane. Various experiments were performed in an attempt to alter the proportion of cells carrying the antigen.
Analysis of prefission morphogenesis in Paramecium aurelia
Authors: Gill Kulbir S. , Hanson Earl D. 
Published: June 2005

AbstractParamecium aurelia has been exposed to varying concentrations of actinomycin D for extended periods and to a high concentration starting at various specific times in the cell cycle. Extended exposures at 5 μg of actinomycin per 1.0 ml of culture medium are lethal as are 24 hour exposures at 20 μ/1.0 ml. Exposures initiated at selected times in the interfission period reveal transition and stabilization points, similar to those found in Tetrahymena, that is, exposure prior to the transition point almost invariably blocks a given developmental event. Exposure after the transition point may or may not result in blockage but exposure after the stabilization point typically never shows blockage. Also the normal sequence of developmental events can be upset by exposure to actinomycin. These results are interpreted as being consistent with sequential action of the genes in the cell cycle and as indicating independence of final genetic control of different developmental processes, though all processes are dependent on common prior events. The macronucleus of exposed cells shows aggregation of dark material that is neither DNA nor RNA, and is probably a protein, but whose normal function is not known.