bluuebunny/crossref_metadata_2025_split huggingface dataset:
Suppression of feather morphogenesis in co‐aggregates of skin cells from embryos of different ages
Authors: Garber Beatrice , Moscona A. A. 
Published: June 2005

AbstractThese experiments test the capacity of younger skin cells to promote feather differentiation in aggregates of older skin cells; the results indicate that the older cells suppressed the normal differentiation of the younger cells.Skin sheets (epidermis and dermis) from the dorsum and from the featherless (apterous) area of 6‐ to 14‐day chick embryos were dissociated into suspensions of single cells and commingled in the following heterochronous combinations: (a) 6‐day dorsal skin cells with 14‐day dorsal skin cells, (b) 8‐day dorsal skin cells with 14‐day dorsal skin cells, (c) 6‐day dorsal skin cells with 10‐day mid‐dorsal skin cells, (d) 6‐day dorsal skin cells with 10‐day apterous skin cells. Single‐age suspensions served as controls. The cells were co‐aggregated in vitro for 24 hours and the resulting aggregates grafted to the chorioallantoic membrane for further development for seven days. In grafts of control aggregates of 6‐ or 8‐day skin cells there was excellent development of feathers; in aggregates of 14‐day cells no feathers developed; aggregates of 10‐day mid‐dorsal cells gave rise to atypical, stunted feathers; aggregates of 10‐day cells from apterous areas produced no feathers.In grafts of 6‐ or 8‐day skin cells co‐aggregated with 14‐day skin cells, there was complete suppression of feather development; the predominant structures were stratified and heavily keratinized skin sheets, characteristic of aggregates of 14‐day skin cells. Grafts of co‐aggregates of 6‐day skin cells with 10‐day mid‐dorsal skin cells gave rise to feathers and skin of patterns characteristic of the 10‐day cells. Six‐day skin cells co‐aggregated with 10‐day apterous skin cells reconstructed feathers and skin of the 6‐day type as well as skin of the 10‐day type.Simple dilution of feather‐forming by non‐feather‐forming cells cannot by itself explain feather suppression in co‐aggregates with cells from older skin and “assimilation” of the younger cells into the morphogenetic pattern of the older cells. It is assumed that the suppression results from interference by constitutents in the older cell population with interactions between specific cell groupings essential for feather development or, with the cellular sorting‐out process by which these groupings arise.
Male gonadal dysgenesis in a female‐sterile mutant of Drosophila melanogaster
Authors: Lucchesi J. C. , Counce S. J. , Hildreth P. E. 
Published: June 2005

AbstractVarious types of testicular abnormalities, encountered in deep orange (dor) Drosophila melanogaster males, have been described. These abnormalities range from complete failure of attachment and, therefore, of elongation and coiling of both testes, to attachment and partial elongation of one testis.The frequency of testicular dysgenesis among affected lines can be readily modified by varying the culture conditions or the genetic background.The occurrence of a relatively high incidence of abnormalities among males bearing an X‐chromosome balancer (FM4) is reported.
Succinic dehydrogenase and cytochrome oxidase of mitochondria of chick liver, heart, and skeletal muscle during embryonic development
Authors: Greenfield Phyllis C. , Boell E. J. 
Published: June 2005

AbstractThe specific activities of succinic dehydrogenase (SD) and cytochrome oxidase (COX) were determined for mitochondria of chick liver, heart, and skeletal muscle from the seventh day of incubation through the time of hatching. The levels of activity of both enzymes at hatching and the rate and course of the developmental changes by which the final levels are reached are different and specific for mitochondria of the three tissues studied. During development changes in activity of both enzymes occur in parallel so that the ratio of SD/COX remains constant. Furthermore, the ratio is the same for the three types of mitochondria. Cytochrome oxidase is completely localized in the insoluble protein fraction (membrane fraction) of all mitochondria examined, and the change in COX during development varies temporally and quantitatively with the proportion of insoluble protein. When calculated on the basis of insoluble protein, specific activities of SD and COX are constant throughout development; furthermore, differences in activity among the mitochondria of the three tissues disappear. It is concluded that mitochondrial differentiation reflects the appearance of specific proportions of membranes and matrix.
Estradiol administration and reproductive performance in rats
Authors: Schultze A. B. , Ellicott A. R. 
Published: June 2005

AbstractEstradiol in doses of 2 and 4 micrograms increased uterine triphenyltetrazolium (TTC) metabolism at day of breeding when administered for two days prior to breeding. Estradiol as administered in these experiments resulted in decreased uterine TTC metabolism at day 4 and 8 of gestation when compared to the metabolism of untreated females.Two micrograms of estradiol administered one and two days prior to breeding increased reproductive performance. Two micrograms of estradiol administered one day prior to breeding and at day of breeding drastically reduced reproductive performance.
Haptoglobin evolution: Polymeric forms of HP in the Bovidae and Cervidae families
Authors: Travis James C. , Sanders Bob G. 
Published: June 2005

AbstractVertical polyacrylamide gel electrophoresis and Sephadex G‐200 chromatography have been used to characterize haptoglobins (Hp) of members of the Bovidae family, goats, sheep, cattle, and bison, and of the Cervidae family, mule deer and elk. In contrast to other mammals with the exception of humans, sera from these animals exhibited polymeric Hp similar to human Hp 2. No Hp polymorphism was demonstrated in these studies, however. Immunological studies with rabbit anti‐goat Hp sera revealed cross reactivities among all members of these two families, but not with human Hp. With anti‐human Hp sera no immunological cross reactivity was observed with any of the sera of these two families. Since a partial gene duplication has been postulated as the source of polymeric Hp and of Hp polymorphism in humans, a similar but independent genetic event is postulated to have occurred in the ancestral line of the Bovidae and Cervidae families to give rise to polymeric Hp.
Genetic and metabolic bases of two “albino” phenotypes in the leopard frog, Rana pipiens
Authors: Smith‐Gill Sandra J. , Richards Christina M. , Nace George W. 
Published: June 2005

AbstractPreliminary characterizations of albino Rana pipiens from two widely separated geographic origins, Mexico and Michigan, indicated that different metabolic basés underlie the albino phenotype.Albinism in the Mexican frogs was shown to result from a single Mendelian recessive gene, am (amelanotic), and appeared to involve a biochemical failure of the pigment synthesizing system. Melanophores were present in am/am integument which exhibited tyrosinase activity when provided with exogenous tyrosine or L‐DOPA. The tyrosinase activity of am/am melanophores showed greater thermolability than did that of wild type malanophores.The “albinism” of tadpoles collected in Michigan was only partial, and was associated with a highly pleiotropic syndrome, abnormal patterning of chromatophore distributions, and metamorphic failure. Poor pigmentation of integumental melanophores appeared associated in part with inhibitors of melanogenesis. Genetic data on the possible mode of inheritance are not yet available.
Growth of mouse trophoblast transplanted to syngeneic and allogeneic testes
Authors: James D. A. , Acierto Suzie , Murphy B. D. 
Published: June 2005

AbstractTrophoblast was transplanted to the testis to study a number of factors which might influence its growth and invasive capacity. Three genotypes were used in reciprocal transplantations and the recipient groups were compared histologically and by examination of the haemorrhagic nodule produced in the testis by the trophoblast. The factors of principal concern were antigenic dissimilarity, the nature of the transplant and the recipient site, and the mass of the transplant and the recipient site.The results indicated that antigenic dissimilarity, mass of the recipient organ, and original trophoblast mass have no appreciable influence on trophoblast growth in the present study system. The nature of the recipient according to its genotype and the nature of the trophoblast do appear to have some influence but this is more apparent from histological examination than from analysis of haemorrhage mass. These findings cast some doubt upon the validity of the analysis which has been used by some investigators.The present findings confirm that a physiological relationship is established between trophoblast and host‐tissue. The relationship appears to be of a qualitative rather than quantitative nature, and that this relationship is established in spite of the proposed protective glyco‐protein barrier between these components.
An analysis of the hemoglobins from some common turtles
Authors: Horton Bennett , Fraser Ronald , Dupourque Daniel , Bailey David , Chernoff Amoz 
Published: June 2005

AbstractA chromatographic analysis of the blood from seven species of turtles, representing four families, has revealed that all animals contained multiple hemoglobins. Members of the Emydidae family had two major components separated by a minor one. There was some variation to this pattern in the box turtles (Terrapenes). The musk, soft shelled, and the snapping turtles examined had three, five, and four hemoglobins respectively. In general, electrophoresis of these proteins in starch gels confirmed the results obtained from DEAE cellulose chromatography in minicolumns.Hemoglobins from the painted and Cumberland turtles were found to be quite resistant to dimerization on aging and to alkali denaturation. These proteins from the box turtles were seen to be moderately resistant to both types of molecular modification, while those from the musk, the soft shelled, and the snapping turtles polymerized readily on aging and denatured readily in alkali.
The effect of gonadectomy and propylthiouracil treatment on the submandibular gland of the Mongolian gerbil, Meriones unguiculatus
Authors: Mastraccio Albert J. 
Published: June 2005

AbstractThe histological organization and cytology of the submandibular glands of male and female Mongolian gerbils were described. A sexual dimorphism in the glands, limited specifically to the serous tubules, was noted. In the male, gonadectomy, propylthiouracil administration and a combination of the two treatments resulted in significantly reduced serous tubule diameters. Such reduction was accompanied by a decrease in the number of cells per tubule without any change in the height of individual serous cells. In the female similar treatments were without effect on these parameters of the serous tubules. Experimental treatments did not affect the cytology or the periodic acid‐Schiff and Alcian blue reactions of the submandibular glands in either sex.
Yolk formation by transplanted cockroach oocytes
Authors: Bell William J. 
Published: June 2005

AbstractIntraspecific transplantation of ovaries in 18 species of cockroaches resulted in the initiation of yolk formation and oocyte growth rates similar to sham‐operated controls. Host vitellogenins were sequestered by transplanted oocytes in concentrations equal to those observed in oocytes of unoperated cockroaches. Ovaries transplanted interspecifically sequestered host vitellogenins and grew to terminal stages only when donor and host were closely related. Yolk formation did not occur when ovaries were transplanted between species of different superfamilies or families, whereas several cases of successful ovary transplantations were observed between species of different subfamilies. Unsuccessful transplants either failed to take up host vitellogenins and did not increase in size or were encapsulated and degenerated.
A fertile male rabbit with a minute Y chromosome
Authors: Martin Patricia A. , Shaver Evelyn L. 
Published: June 2005

AbstractNineteen of 33 or 58% of six‐day blastocysts, recovered from four female rabbits demonstrated an apparent male chromosomal complement with a minute Y chromosome. The remaining 42% of the blastocysts had a normal female XX chromosomal complement. All four female rabbits, two California and two New Zealand White, were inseminated by a particular California male rabbit. Chromosome studies of peripheral blood cultures from the male, which had normal gonadal and genital anatomy as well as normal fertility, revealed a karyotype identical to that seen in the blastocysts with the apparent male chromosomal complement. Autoradiographic studies from blood cultures of the male indicated that the minute chromosome was late‐replicating and was most likely the Y chromosome. The suggestion is made that the rabbit may be another mammal with Y chromosome polymorphism.
Fine structure of epidermal differentiation in the mouse
Authors: DuBrul Ernest F. 
Published: June 2005

AbstractThe structure of the epidermis of mice from nine days in utero to adult has been studied with the electron microscope. During fetal development the epidermis increases in thickness and four structurally distinct regions are present by 15–17 days in utero. Fetal epidermis differs from adult epidermis by the presence of large, tripartite keratohyalin granules in the superficial layers. Such structures are absent in adult epidermis. Furthermore, there are fewer tonofilament bundles in fetal epidermis, and no cornified layer containing 100 Å keratin fibers is found in the fetal stages. A peridermal layer is also present in the fetus.
The fate of transplanted cells in mouse blastocysts in vitro
Authors: Moustafa Laila A. , Brinster R. L. 
Published: June 2005

AbstractFour‐day synchronous blastocyst donor cells and 8‐ and 12‐day asynchronous embryonic cells were transplanted adjacent to and within the inner cell mass of four‐day recipient blastocysts. Virtually all recipient blastocysts tolerated micrurgical procedures and regained their “normal” size and shape after four hours of incubation. About 3% of all recipient blastocysts exhibited rejected cells.The nuclei of the transplanted cells, labeled with tritiated thymidine, appeared to be present in various phases of the cell cycle 20 hours after transplant. After 40 hours in culture, the number of labeled cells was significantly greater than the number of cells transplanted in both the synchronous and asynchronous transplants. The present study shows for the first time that chronologically older cells can divide in a younger embryo and suggests that they participate in the structure of the recipient embryo.
Changes in codon recognition and chromatographic behaviour of tRNA species during embryonic development of the sea urchin Paracentrotus lividus
Authors: Molinaro M. , Farace M. G. 
Published: June 2005

Abstract14C‐ or 3H‐aminoacyl‐tRNA from fertilized eggs and from embryos at the pluteus stage were analyzed by chromatography on benzoylated DEAE cellulose columns. Differences in the chromatographic species between the two stages were found for lysyl‐ arginyl‐ and leucyl‐tRNA. No differences were observed for valyl‐ and seryl‐tRNA.Leucine, lysine, serine and arginine tRNA from both stages of development were tested for codon recognition by the ribosomal binding technique. At the pluteus stage, the binding to ribosomes of lysyl‐tRNA is about five fold higher in the presence of poly AG than in the presence of poly A, whereas the difference is only two fold in fertilized eggs. Poly AG stimulates the binding of arginyl‐tRNA from both stages. At 0.02 M Mg+2 the stimulation is increased in pluteus tRNA while it is decreased in the tRNA of fertilized eggs. Moreover at this magnesium concentration the binding of pluteus arginyl‐tRNA is stimulated by poly G. Less remarkable quantitative differences in codon recognition between the two stages were observed for seryl‐tRNA, while the codon recognition by leucyl‐tRNA does not vary during development.
Caffeine bleaching of Stentor coeruleus
Authors: Tartar Vance 
Published: June 2005

AbstractAfter a few days in caffeine solution the dark blue‐green ciliate Stentor coeruleus loses all visible pigmentation. The cells remain viable and transparent if the solution is then diluted. In time, however, a light pink color is regenerated in maintenance concentration of the drug. In caffeine‐free medium the major dark green pigment is regenerated. Decolorized, pink, and normal stentors can thus be compared, alive, in searching for the functions of these pigments. Unexpectedly, the pigments are not necessary for the lightavoidance response.
Response of the toad, Xenopus laevis, to circulating antigens. II. Responses after splenectomy
Authors: Turner Rodney J. 
Published: June 2005

AbstractIt was demonstrated that the spleen cannot be the only site of antibody induction or formation in Xenopus laevis — even though cellular activity in response to circulating antigen is most evident in this organ — since serum antibody titres in splenectomized toads were comparable with those in sham‐operated animals after immunization with human gamma globulin (in adjuvant) or with sheep erythrocytes. This is of interest since the spleen appears to be the only lymphoid organ in X. laevis with any complexity of structural organization, the remaining foci consisting mainly of irregularly arranged lymphocytes. These experiments indicate that complex structural organization of lymphoreticular tissues may not be essential to immunological competence.
Effect on lens regeneration of implantation of spinal ganglia into the eyes of the newt, Notophthalmus
Authors: Powell Jeanne A. , Powers Christine 
Published: June 2005

AbstractHomologous implantation of brachial spinal ganglia from intact animals into the vitreous chamber of the newt eye had no effect on initiation of lens regeneration from the dorsal margin of the iris in the absence of both adult lens and retina; while implantation of ganglia innervating regenerating limbs resulted in an increased rate of lens regeneration as compared to contralateral eyes in which nothing or a piece of liver had been implanted. Ganglia innervating regenerating limbs were also capable of initiating lens regeneration in the presence of an intact lens. Such lens regeneration proceeded no further than nuclear activation and depigmentation of iris tissue even after 18 days of ganglia culture in the anterior chamber of the newt eye. This limited response may be due to insufficient amount of trophic factor(s) because of the size of the implant or the duration of its production by the implant. It is suggested that the neural trophic factor influencing limb regeneration may also be capable of initiating lens regeneration and substituting for the retinal trophic factor in the eye.
On the rate of movement of the cleavage stimulus in sand dollar eggs
Authors: Rappaport R. 
Published: June 2005

AbstractThe rate at which the cleavage stimulus moves from the mitotic apparatus to the cell surface was calculated from measurements made on flattened, fertilized Echinarachnius parma eggs with excentric nuclei. The time interval between the appearance of furrows in the closer and more distant equatorial margins is proportional to the difference in the distance between the axis of the mitotic apparatus and the two surfaces. The calculated rate of stimulus movement is 6.3 ± 1.8 μ/minute. This rate is slower than that of free diffusion, and the usually studied examples of cytoplasmic streaming; it approximates that reported for microtubule growth.
An ultrastructural analysis of polyspermy in the surf clam, Spisula solidissima
Authors: Longo Frank J. 
Published: June 2005

AbstractSpisula eggs made polyspermic by insemination with high concentrations of sperm were prepared for light and electron microscopy. In eggs that had been inseminated by at least eight spermatozoa, incorporation and male pronuclear development were morphologically similar to events observed in monospermic zygotes. Subsequent to their migration to the central region of the zygote the female pronucleus and the male pronuclei become closely associated. This is followed by chromosome condensation and vesiculation of the pronuclear envelopes. The chromosomes become arranged on a multipolar spindle in preparation for the first cleavage division. In approximately 50%zygotes one of the pronuclei appears to be asynchronous in its morphogenesis; the vesiculation of its envelope and the condensation of its chromatin taking place at a later stage than in adjacent pronuclei. This pronucleus fails to form discrete chromosomes and is recognized as a large spheroidal body which becomes aligned on the multipolar spindle. The fate of this mass of condensed chromatin is unknown.
Stimulation of RNA synthesis in developing frog embryos by microinjection of ribosomes
Authors: Rollins J. W. , Flickinger R. A. 
Published: June 2005

AbstractOocyte ribosomes stimulate H3–5–uridine incorporation into RNA when microinjected into the vegetal cells of early cleavage embryos. Preparations with a low percentage of monosomes, such as those of swimming larvae and adult frog liver, give little stimulation. E. coli ribosomes fail to affect RNA synthesis. Short term labeling experiments at the gastrula stage in which only nuclear RNA was labeled suggest that added ribosomes may increase nuclear transcription and not cytoplasmic conservation of D‐RNA in polysomes.
The function of the middle ear in lizards: Eumeces and Mabuya (Scincidae)
Authors: Wever Ernest Glen 
Published: June 2005

AbstractThe structure of the middle ear and its performance in the reception of sounds are considered in four species among the Scincidae. By use of the alternating potentials of the cochlea the sensitivity to sounds of various frequencies was measured under normal conditions and after certain alterations of the conductive mechanism designed to reveal its operation. By excluding the major part of this mechanism and applying aerial sounds through a tube sealed over the oval window, an assessment was made of the enhancement of sensitivity ordinarily provided by the mechanism acting as a mechanical transformer.Further analysis of the action of the conductive mechanism was carried out
by stimulation with mechanical vibrations applied to the system in dif
ferent ways.An increase in the effective force of sound vibrations acting on the cochlear
elements, which is required in the middle ear's operation as an impedance
transformer, appears to be achieved by a combination of two mechanical
processes, a lever action in the ossicular chain and a form of hydraulic ampli
fication through the difference in areas between tympanic membrane and
stapedial footplate.The improvement of sensitivity in the action of the middle ear was found
to be highly significant in amount in all specimens. This amount varied some
what with species and among individual ears, but averaged 37.8 db. This
average compares closely with the results of previous experiments on Iguanidae
and Gekkonoidea, and is of the same order of magnitude as corresponding mea
surements made on mammalian ears.