bluuebunny/crossref_metadata_2025_split huggingface dataset:
Benzamide on chondrocytic differentiation in chick limb bud cell culture
Authors: Nakanishi Shinobu , Uyeki Edwin M. 
Published: April 2021

ABSTRACT
Benzamide, an inhibitor of (ADP-ribose) transferase, augmented chondrocytic differentiation of chick limb bud mesenchymal cells in micromass cultures; the incorporation of 35SO42- into the trichloroacetic-acid-insoluble constituents of cell masses as well as the formation of cartilage nodules (Nishio, Nakanishi, Doull & Uyeki, 1983) occurred about 24h earlier than in untreated cultures and continued to be enhanced in benzamide-treated cultures of stage 23-to 24-chick limb bud cells. Benzamide also significantly increased cell proliferation. However, benzamide did not affect DNA and RNA syntheses except for one period: 24 to 30 h after the start of culture, RNA synthesis was stimulated. From 48h of culture, (ADP-ribose) transferase activity decreased daily in untreated cultures, whereas benzamide treatment diminished (ADP-ribose) transferase activity 24 h earlier. On the other hand, intracellular NAD levels increased daily in untreated cultures, and benzamide significantly increased the NAD levels above untreated cultures. ATP levels did not differ significantly during the culture period, and benzamide did not affect ATP levels.
Localization of the factors producing the periodic activities responsible for synchronous cleavage in Xenopus embryos
Authors: Shinagawa Atsunori 
Published: April 2021

ABSTRACT
This paper investigates the localization within the Xenopus egg of the factors responsible for the periodic activities such as the cyclic rounding-up and flattening, related to the cleavage cycle. Denuded eggs were bisected along the boundary line between the animal and the vegetal hemispheres immediately after being rotated through 90° off the vertical axis (Early Bisection). The resulting animal halves, though prevented from cell division by colchicine, showed typical periodic rounding-up as previously observed in enucleated egg fragments, whereas the vegetal halves did not. This result indicates that the factors inducing the periodic rounding-up are not distributed uniformly throughout the egg but localized mostly in the animal hemisphere. Furthermore, the distribution of these factors between the cortex and endoplasm of the animal hemisphere was investigated. Eggs were separated into animal and vegetal halves following incubation for 30min after the 90°-off axis rotation (Late Bisection). During this incubation the endoplasmic components become relocated in the rotated egg under the force of gravity. After the rotation, the Late-Bisected vegetal halves showed typical cyclic rounding-up in contrast to those formed by Early Bisection. These results suggest that the factors inducing the periodic rounding-up (and probably also many other cyclic activities, closely linked with the rounding-up movement) are localized in endoplasmic components which can be displaced by gravity from the animal to the vegetal hemisphere of the Xenopus egg.
Origin of the irideal striated muscle in birds
Authors: Nakano Kensuke E. , Nakamura Harukazu 
Published: April 2021

ABSTRACT
The aim of the present study was to elucidate the origin of the striated muscle cells in the avian iris. For this purpose we adopted interspecific transplantation between quail and chick embryos because quail cells can be used as biological markers in this system. We transplanted isotopically and isochronically (6- to 7-somite stage) a fragment of a dorsal part of the quail neural anlage into a chick embryo at the level corresponding to the posterior prosencephalon and the mesencephalon on the right-hand side.
In the chimaeric embryo, the iris epithelium comprised host chick cells, while most of the stromal cells of the iris on the operated side possessed the quail nuclear marker. At 19 days after the operation, the striated muscle cells had differentiated in the chimaeric embryo. These cells, as well as connective tissue cells and the Schwann cells of the iris of the chimaera, were shown to possess typical quail nuclei by light and transmission electron microscopy. From these findings, we conclude that the striated muscle cells originate from the neural crest.
Development of the lateral line system in Xenopus laevis : III. Development of the supraorbital system in triploid embryos and larvae
Authors: Winklbauer Rudolf , Hausen Peter 
Published: April 2021

ABSTRACT
During normal development of the supraorbital lateral line system of Xenopus, an elongated streak of primordial cells becomes subdivided into a linear series of cell groups containing only about eight cells each, thus forming a row of primary lateral line organs (Winklbauer & Hausen, 1983a,b). In triploid Xenopus embryos, cell size is 1 ·5 × normal. When the formation of lateral line organs occurs in triploid primordia, the nascent organs contain only about five or six cells each, i.e. about two thirds of normal. Thus, the increase in cell size is compensated for by a corresponding reduction in cell number, keeping constant the organ size in terms of total cell mass or volume. This result excludes a cell counting mechanism for determining organ size. In diploids, the primary organs, although being of equal size initially, differ vastly in their final size and exhibit a peculiar frequency distribution of organ sizes. A detailed quantitative model for supraorbital lateral line development has been proposed, which accounts for this characteristic frequency distribution (Winklbauer & Hausen, 1983b). This model makes precise predictions as to the frequency distribution of the final size of triploid lateral line organs, where the initial organ size is reduced to five or six cells. These predictions were verified experimentally.
Detection and characterization of spatial pattern in chimaeric tissue
Authors: H. Schmidt Günter , Wilkinson Maureen M. , Ponder Bruce A. J. 
Published: April 2021

ABSTRACT
The mosaic pattern of patches of crypts of Lieberkühn in chimaeric C57BL/6JLac (B6) ↔DDK mouse small intestine, demonstrated using Dolichos bifloras agglutinin as strainspecific marker, is quantitatively examined using the Greig-Smith analysis of variance. This analysis, widely used in ecological research, provides a method to detect and characterize pattern at various scales. The analysis demonstrates that B6 patches are non-randomly distributed at all scales examined. A consistent increase in the intensity of pattern at one particular scale over all replicate samples identifies ‘clusters of clusters’ which probably are territories of ‘descendent’ clones. The sizes of descendent clones, either in terms of numbers of patches or total numbers of crypts, are highly variable. A steady reduction in the strength of pattern from proximal to distal is found. The Greig-Smith analysis of variance provides a valuable method for the analysis of pattern in chimaeric tissue.
The influence of the epithelium on palate shelf reorientation
Authors: Bulleit Robert F. , Zimmerman Ernest F. 
Published: April 2021

ABSTRACT
The intrinsic forces necessary for directing the reorientation of the secondary palate appear to reside in the anterior two thirds of the palate or presumptive hard palate. The hard palate could reorient regardless of whether it was intact or separated from the posterior third or presumptive soft palate. The soft palate could only reorient if the palate shelves are left intact. These intrinsic forces, within the hard palate, may be mediated by the mesenchymal cells, their extracellular matrix, or the epithelium surrounding the shelves. This latter possibly was tested by removing the epithelium, from either the presumptive oral or nasal surface followed by measurement of reorientation in vitro. Only after removal of the oral epithelium was a significant inhibition in reorientation observed. The treatment used to remove the epithelium, EDTA and scraping, was shown to remove 41 % of the oral epithelium leaving the majority of the basement membrane intact. The observed inhibition of reorientation did not appear to be a consequence of wound healing. Creation of wounds twice the area that was observed after treatment with EDTA and scraping inhibited reorientation minimally. These results suggest that the epithelium and particularly the anterior oral epithelium plays a major role in the reorientation of the murine secondary palate.
The development of 12th to 14th day foetuses following reimplantation of pre- and early-primitivestreak-stage mouse embryos
Authors: Beddington R. S. P. 
Published: April 2021

ABSTRACT
This paper describes a technique for transplanting early postimplantation mouse embryos from their own implantation site to a decidua in another pregnant mouse. Evidence is provided that this procedure is compatible with their continued development. At a low frequency both 6th and 7th day embryos can re-establish themselves and continue apparently normal development and placentation for at least 6 –8 days.
Clonal analysis of X-chromosome inactivation and the origin of the germ line in the mouse embryo
Authors: Gardner R. L. , Lyon M. F. , Evans E. P. , Burtenshaw M. D. 
Published: April 2021

ABSTRACT
Cloning of cells from peri-implantation embryos by blastocyst injection was used to investigate the time of X-chromosome inactivation in that part of the ectoderm lineage giving rise to foetal tissues of the mouse. Matings were arranged so that the two X-chromosomes of female donor cells controlled two distinct coat colours and host blastocysts were of a third colour genotype. No coat chimaeras were obtained in experiments using donor cells from the primitive ectoderm of 6th or 7th day embryos or from lactationally delayed implanting or reactivated blastocysts. In contrast, a minimum of 80 unequivocal coat chimaeras were obtained in experiments in which primitive ectoderm cells from 5th day implanting blastocysts were used for injection. The majority of these chimaeras that had received a female cell exhibited both donor colours in addition to host colour in their coats, suggesting that the donor cell had not undergone X-inactivation until one or more cycles after transplantation. The remainder of such chimaeras exhibited only one or other donor coat colour. Determination of the parental origin of the allocyclic X-chromosome in donor metaphase preparations in internal tissues of several chimaeras revealed that the coat pattern did not always reflect the X-activity status of the donor cell clone as a whole. Nevertheless, the findings suggest that X-inactivation takes place shortly after implantation in the primitive ectoderm cell population from which the foetus is derived.
Of the 68 chimaeras in which the sex of both the donor and host component was established 62 proved to be fertile. Furthermore, 21 of the 37 fertile chimaeras whose sex corresponded with that of the donor cell yielded functional gametes of donor origin. Injection of cells from a single donor blastocyst into a series of host blastocysts established that at least 2 cells in 5th day primitive ectoderm can give rise to both somatic cells and functional germ cells among their mitotic descendants.
Fluid transport across the epiblast of the early chick embryo
Authors: Stern Claudio D. , Manning Simon , Gillespie James I. 
Published: April 2021

ABSTRACT
A simple method is described which allows quantitation of the rate of fluid transport across the isolated epiblast of the early chick embryo. This method consists of allowing the tissue to form spheres, which then spontaneously undergo a large volume increase. The rate of fluid uptake into the spheres can be estimated by measuring the dimensions of the spheres. Pharmacological and electrophysiological studies were performed on the spheres to determine the mechanisms of fluid transport. It was found that fluid is driven into the interior of the spheres by the osmotic gradient generated by unidirectional sodium transport and to a lesser extent by another mechanism, as yet unknown. We discuss possible candidates for this mechanism, and consider the significance of these findings to early development.
In vivo and in vitro cultured mouse preimplantation embryos differ in their display of a teratocarcinoma cell surface antigen: possible binding of an oviduct factor
Authors: Gaunt Stephen J. 
Published: April 2021

ABSTRACT
By use of a monoclonal antibody, 2B5, in indirect immunofluorescence experiments, it was found that both fertilized and unfertilized mouse eggs obtained directly from the oviduct commenced expression of a cell surface antigen at about 5h after ovulation. Surface labelling became intense by 16 h after ovulation and persisted over all blastomeres throughout preimplantation development. In contrast, embryos cultured in vitro did not show appearance of 2B5 antigen until about 48 h after ovulation, at which time they were at the 2-to 4-cell stage. Antigen expression in vitro commonly began on a single blastomere and did not appear consistently over all blastomeres until the 8-cell stage (72h after ovulation). Unfertilized eggs maintained for 72 h in culture did not acquire 2B5 antigen. It is postulated that the absence of 2B5 antigen on 1-cell eggs cultured in vitro may be due either to a failure of normal synthesis by eggs as a result of a deficiency in the culture medium, or alternatively, to absence of a soluble oviduct factor which carries the 2B5 antigen, and which normally becomes bound to the surface of eggs after ovulation. The second of these two possibilities was supported by egg transfer experiments which showed that unfertilized eggs within the oviduct became 2B5 antigenpositive even after their prior fixation in glutaraldehyde. By the 2-to 4-cell stage, however, embryos developed their own capacity for synthesis of 2B5 antigen-positive cell surface molecules. This synthesis was inhibited by tunicamycin, suggesting that the antigenic site involved the sugar component of glycoprotein. The range of tissues within the postimplantation embryo and adult reproductive tracts which labelled with 2B5 antibody was found to be very similar to that known for SSEA-1 monoclonal antibody (Solter & Knowles, 1978; Fox et al. 1981; Fox, Damjanov, Knowles & Solter, 1982), and as further evidence of a relationship between 2B5 and SSEA-1 antigens it was found that 125I SSEA-1 antibody could be blocked in its binding to teratocarcinoma cells by preincubation in 2B5 monoclonal antibody.
Quantitation of two-dimensional gel proteins reveals unequal amounts of Tcp-1 gene products during mouse spermatogenesis but no correlation with transmission ratio distortion
Authors: Sánchez Edwin R. , Hammerberg Craig , Erickson Robert P. 
Published: April 2021

ABSTRACT
The discovery of a protein, p63/6.9, that is synthesized by both somatic and germ cells and coded for by a gene, Tcp-1, within the t complex provides a molecular probe for examining transmission ratio distortion in t mice. Two electromorphs of this protein exist. The acidic protein (a) is encoded by t-haplotype chromosomes, while the basic protein (b) is encoded by wild-type 17th chromosomes. We have measured the relative amounts of p63/6.9a and p63/6.9b for various t-complex bearing males and for several stages of spermatogenesis. There was no correlation between the ratio of p63/6.9a to b and the magnitude of transmission ratio distortion but the relative amounts of these proteins present in testicular cells can vary depending on the method of labelling. In vivo labelling results in the detection of two-fold greater amounts of p63/6.9a while in vitro labelling produces equimolar amounts of these two proteins. These data suggest that unequal synthesis or degradation of the p63/6.9 proteins occurs during sperma-togenesis. It is proposed that increased synthesis of p63/6.9a in vivo is an intrinsic property of t-haplotypes.
Cell distributions in the retinal ganglion cell layer of adult Leptodactylid frogs after premetamorphic eye rotation
Authors: Dunlop S. A. , Beazley L. D. 
Published: April 2021

ABSTRACT
In adult Limnodynastes dorsalis and Heleioporus eyrei regions of high cell density in the retinal ganglion cell layer are normally found along the nasotemporal axis and become apparent only after metamorphosis (Dunlop & Beazley, 1981; Coleman, Dunlop & Beazley, 1984). Eye rotations were performed from embryonic to mid-larval life and cell topography mapped after metamorphosis using cresyl violet-stained wholemounts. Mature cell distributions indicated that from stages equivalent to 30/31 in Xenopus (Nieuwkoop & Faber, 1956) alignment of high cell density regions had already been determined and developed to reflect the degree of eye rotation. We conclude that cell topography in the adult ganglion cell layer is determined from the time at which invagination of the eye cup nears completion. Furthermore, the corre-spondence in adults between alignment of high cell density regions and the orientation of the visuotectal projection suggests that these features could not be dissociated by manipulation of the developing eye.
Muscle fibre types and innervation of the chick embryo limb following cervical spinal cord removal
Authors: Laing N. G. , Lamb A. H. 
Published: April 2021

ABSTRACT
Several segments of spinal cord were removed from the cervical regions of stage-13 or -14 (day-2) chick embryos. After further incubation to day 17 or 18, the patterns of end-plate distribution and ATPase typing of muscle fibres in the anterior and posterior latissimus dorsi and the ulnimetacarpalis dorsalis, and the ATPase typing of the forearm muscles were examined. No differences from control embryos were found. The embryos had normal numbers of lateral motor column motoneurons in both the brachial and lumbar enlargements and the positions of motoneurons supplying the biceps as identified with retrograde horseradish peroxidase labelling were consistent with the normal patterns of motor projection into the limb. These results show that the fibre typing of limb muscles and their patterns of innervation are independent of descending inputs until just before hatching in the chick.
Utilization of cytoplasmic poly(A)+ RNA for protein synthesis in preimplantation mouse embryos
Authors: Kidder Gerald M. , Conlon Ronald A. 
Published: April 2021

ABSTRACT
The distribution of cytoplasmic poly(A)+RNA between subribosomal (&lt;80S) and ribosomal/polysomal (⩾80S) ribonucleoprotein particles has been investigated in mouse morulae and blastocysts. After labelling for 24h with [5,6-3H] uridine, late morulae (96h post-hCG), early blastocysts (100h post-hCG), or late blastocysts (120h post-hCG) were homogenized in detergent buffer, and 11000 g supernatants were prepared and centrifuged through 15–40% sucrose gradients. Poly(A)+RNA was isolated from the appropriate gradient fractions by affinity chromatography. In late morulae beginning to undergo cavitation, poly(A)+RNA was evenly distributed between the two types of RNP particles whereas it was almost entirely in the ribosomal/polysomal fraction in early and late blastocysts. The sedimentation profile (in 5–20 % sucrose gradients) of poly(A)+RNA from the ribosomal/polysomal fraction of late morulae and blastocysts was the same, with a range of 4S to greater than 28S and a modal peak slightly smaller than 18S. Roughly 75 % of this RNA was judged to be functional mRNA based on the EDTA sensitivity of the RNP particles containing it. Poly(A)+RNA from the subribosomal fraction of late morulae displayed a similar range of sedimentation values, but was enriched for a component sedimenting at 6–7S. These results demonstrate that the subcellular distribution of poly(A)+RNA shifts as cavitation begins, with the decline of the non-translating, subribosomal fraction. Although most of this fraction in late morulae is probably too small to constitute translatable mRNA, the remainder may represent a reserve available for recruitment into polyribosomes to support blastocyst expansion. Since little non-translating mRNA exists in blastocysts, the increasing rate of protein synthesis during blastocyst expansion must be driven by mRNA accumulation and/or stabilization.
Microgravity simulation as a probe for understanding early Xenopus pattern specification
Authors: Neff Anton W. , Malacinski George M. , Chung Hae-Moon 
Published: April 2021

ABSTRACT
Pattern specification in early amphibians {Xenopus) was monitored in embryos subjected to gravity compensation (microgravity simulation) by constant low-speed rotation on a horizontal axis (clinostat). The useful range of clinostat speeds was determined empirically. The results were interpreted in terms of a set of models which account for the reorganization of the egg cytoplasm that follows fertilization and that correlates with the establishment of dorsal/ventral polarity. Large percentages of clinostated eggs displayed a positive result (normal axial structure morphogenesis). Consequently, normal development of amphibian eggs in the microgravity environment of space should be possible. Models which depend upon gravity-driven rearrangements for cytoplasmic organization (e.g. dorsal/ventral polarization) of the early embryo should, therefore, not be favoured. At several clinostat speeds symmetrization of the egg in accordance with the site of sperm penetration, a natural phenomenon, was altered. The results at those clinostat speeds indicate that models which employ sperm entrance as an obligatory feature of the cytoplasmic rearrangements that generate egg polarity are not applicable.
Identification of proteins and mRNAs in isolated yellow crescents of ascidian eggs
Authors: Jeffery William R. 
Published: April 2021

ABSTRACT
The yellow crescent or myoplasm is a localized cytoplasmic region in eggs of the ascidian Styela that is partitioned to the larval tail muscle and mesenchyme cells during embryonic development. To determine whether the myoplasm contains a specific subset of maternal macromolecules, its abundant proteins and mRNAs were identified and compared to those present in the remainder of the egg. This was accomplished by exploiting a newly developed method for the mass fractionation of yellow crescents which is based on the presence of a unique cytoskeletal domain in the yellow crescent region. The fractionation yields a yellow crescent fraction (YCF) representing the myoplasm and a supernatant fraction representing the non-myoplasmic regions. The YCF comprises structures which contain the characteristic myoplasmic organelles and about 10% of the protein, 8% of the RNA, and 1–3% of the poly (A) of whole eggs. Two-dimensional gel electrophoresis indicated that the YCF contains 15 polypeptides that are undetectable in the supernatant fraction and 43 polypeptides that are significantly depleted in the latter fraction. The proteins restricted to the YCF are both of cytoskeletal and non-cytoskeletal origin. In vitro translation of RNA in a message-dependent lysate and analysis of [35S]methionine-labelled polypeptide products by two-dimensional gel electrophoresis did not reveal qualitative differences between the YCF and the supernatant fraction. Furthermore, the mRNAs coding for two polypeptides that were localized in the myoplasm were not restricted to the YCF. The results suggest that qualitative differences in proteins but not in prevalent mRNAs exist between the yellow crescent and the other cytoplasmic regions of Styela eggs.