bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stress: a global multidimensional common denominator
Authors: Halbreich Uriel 
Published: April 2021

SUMMARYThe manifestations of stress are diverse and culturally and individually determined, but it is present in every culture, every socioeconomic level and – it is global. Introducing a special BJPsych Advances issue on stress, this editorial outlines research questions to be examined and first actions to be taken in the multidimensional sphere of stress, highlighting the need for a collaborative interdisciplinary approach in both research and practice.
Determination of Cell Function in an Insect
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
I Propose to consider two kinds of determination and differentiation which have been studied in the hemipteron Rhodnius prolixus. (i) The determination of the cell or group of cells, with their subsequent differentiation to produce a given part of the body, (ii) The determination or control of the characters of that part—whether these are to be juvenile (larval) or adult (imaginal). Discussion of this second type of determination will require consideration of the role of hormones in controlling differentiation in insects.
The Effect of Excess Vitamin A on the Differentiation of Chick Ectoderm in Culture1
Authors: Fell Honor B. 
Published: April 2021

ABSTRACT
This investigation was made in collaboration with Sir Edward Mellanby, F.R.S. (National Institute for Medical Research, Mill Hill). It has long been known that in animals suffering from vitamin A deficiency, mucous epithelia are replaced by keratinizing epithelium of the epidermoid type. Since keratinization is promoted by lack of vitamin A, it seemed possible that it might be inhibited by an excess of the vitamin. Series of cultures were therefore made in which explants of the ectoderm and underlying tissue from the trunk and limbs of 6–7-day chick embryos were grown by the watchglass or hanging-drop methods; the explants from one side of each embryo were grown in normal medium, and corresponding fragments from the opposite side in medium to which about 1,800 i.u. per 100 c.c. of vitamin A had been added ( + A medium).
Interference of Amino-acid Analogues with Normal Embryonic Development1
Authors: Herrmann Heinz 
Published: April 2021

ABSTRACT
The study of the reactions of the embryonic organism to chemical substances is one of the main approaches to the analysis of embryonic development. Well known is the use of the lithium ion which produces in embryos of diverse species a variety of developmental abnormalities. However, in the case of a substance like lithium an analysis of the particular sequence of chemical reactions which leads eventually to the manifestation of a morphological abnormality encounters a peculiar difficulty. Since lithium reacts with numerous proteins, a wide range of reactions has to be considered as the initial step in the teratogenic mechanism.
Basic Mechanisms in the Differentiation of Pigment Cells
Authors: Willier B. H. 
Published: April 2021

ABSTRACT
Some of the basic mechanisms of cellular differentiation have been elucidated by an experimental analysis of the underlying factors and conditions which control the processes of differentiation of the pigment cell in the chick embryo. The pigment cell, owing to its singular capacity to synthesize melanin pigment granules, is an ideal cell for locating its site of origin and tracing its subsequent pathways to the skin and derivatives, the feather papillae. It has the further advantage that its specific behaviour is recorded as colour or colour pattern in the mature feather. In other words, by using the pigment-forming cell as a ‘marker’ many of its properties in time and space may be ascertained from the moment that it is first set aside as a specialized strain of cell until it reaches its ultimate position and visible expression in the growing feather papilla.
Formation of primary and secondary myotubes in rat lumbrical muscles
Authors: Ross J. J. , Duxson M. J. , Harris A. J. 
Published: April 2021

ABSTRACT
Numbers of myoblasts, primary myotubes and secondary myotubes in developing rat embryo hindlimb IVth lumbrical muscles were counted at daily intervals up until the time of birth, using electron mi-croscopy. Motoneurone death at the spinal cord level supplying the lumbricals was assessed by counting axons in the 4th lumbar ventral root. Death of the motoneurones that supply the intrinsic muscles of the hindfoot was monitored by comparing the timecourse of development of total muscle choline acetyltransferase activity in control embryos with that in embryos where motoneurone death was inhibited by chronic paralysis with TTX, and by counting axons in the mixed nerve trunks at the level of the ankle at daily intervals. Condensations of undifferentiated cells marking the site of formation of the muscle were seen on embryonic day 15 (E15). Primary myotubes began to appear on E16 and reached a stable number (102 ± 4) by E17. Secondary myotubes first appeared two days later, on E19, and numbered 280 at the time of birth (E22). The adult total of about 1000 muscle fibres, derived from both primary and secondary myotubes, was reached at postnatal day 7 (PN7) so considerable generation of secondary myotubes occurred after birth. There was a linear correlation between the number of undifferentiated mononucleate cells in a muscle and the rate of formation of secondary myotubes. The major period of motoneurone death in lumbar spinal cord was during E16-E17, when axon numbers in the L4 ventral root fell from 12000 to 4000, but a discontinuity in the curve of muscle ChAT activity versus time indicated that death in the lumbrical motor pool occurred during E17-E19, after all primary myotubes had formed and before generation of secondary myotubes began. We suggest that motoneurone death, by regulating the final size of the motoneurone pool, regulates the ratio of secondary to primary myotube numbers in a muscle.
Immunochemical demonstration of the clonal organization of chimaeric mouse epidermis
Authors: Schmidt Günter H. , Bloun Margaret A. , Ponder Bruce A. J. 
Published: April 2021

ABSTRACT
The clonal organization of chimaeric mouse epidermis was demonstrated by in situ staining of whole-mount preparations using monoclonal antibodies directed against H-2k and H-2b antigens. A striking pattern of transversely oriented stripes or patches was found which extended from mid-dorsum to the flank region. The orientation of these patches indicates a preferred directional expansion of clones during the development of dorsal/lateral epidermis. The clonal pattern of the belly region differed in that stripes were not found, but a marked ventral midline boundary was observed. This demarcation line may be due to a physical effect, i.e. isolation of the left and right ventral halves of the epidermis during early embryogenesis with relatively little cell mingling following closure of the abdominal wall. The obvious nonhomogenous distribution of chimaeric components in dorsal/lateral and ventral epidermis contradicts assumptions of homogenous, fine-grained patchiness derived from electrophoretic analysis of tissue samples and used in studies of skin carcinogenesis.
The observation that hair follicles may contain cells of both parental genotypes implies a polyclonal origin. Epidermal proliferative units as described by Potten (1974) were not revealed by the pattern of mosaicism at the cellular level in these chimaeric tissue sheets. This indicates that the proliferative compartment of each putative epidermal unit is polyclonal.
Do trophectoderm and inner cell mass cells in the mouse blastocyst maintain discrete lineages?
Authors: Dyce Jonathan , George Martin , Goodall Harry , Fleming Tom P. 
Published: April 2021

ABSTRACTThe extent to which trophectoderm (TE) and inner cell mass (ICM) lineages in the mouse blastocyst remain distinct during the period from the commencement of cavitation up until 48 h later in culture was investigated. Fluorescent latex microparticles were used to label exclusively all TE cells in nascent blastocysts and the position of labelled progeny in cultured blastocysts was examined by disaggregation, by serial sectioning and by whole-mount analyses. The results indicate that, in most blastocysts (80–90 %), TE and ICM lineages are entirely separate during this period while in the remainder lineage crossing is limited usually to only one or two cells of either tissue.
Cytokeratin polypeptide expression during the histogenesis of guinea pig submandibular salivary gland
Authors: Marshak Gabriel , Leitner Orith , Geiger Benjamin 
Published: April 2021

ABSTRACT
The present study was directed towards the characterization of cell-specific histogenetic markers for the various epithelial elements of the adult and the developing guinea pig submandibular salivary gland. We have employed immunofluorescent labelling using three cytokeratin monoclonal antibodies, for which the polypeptide specificities towards guinea pig cyto-keratins were determined. All the epithelial elements of the adult gland were positively labelled with two monoclonal antibodies, namely KG 8.13 (‘broad spectrum’ anti-cytokeratin) and antibody KsB.18 (reactive with a simple cytokeratin-specific polypeptide of 49× 103Mr). Antibody KS8.58 (reactive with a guinea pig cytokeratin polypeptide of 50×103Mr) labelled the basal cells of the large ducts, as well as the myoepithelium. During development of the gland, the submandibular anlage and its primary and secondary branches with their terminal buds, were uniformly labelled with the three antibodies; however, the cytokeratin polypeptides reactive with antibody KS8.58, which were apparently expressed in all cells of the developing ducts, gradually disappear from most of the ductal cells, starting at about 6 weeks of gestation, and remain only in the basal or reserve cells of the large ducts and the myoepithelium. These observations support the notion that the basal cells retain at least some of the properties of the embryonic glandular epithelium and could be considered as pluripotent reserve cells which may function as progenitors for other epithelial elements in the salivary glands epithelia.
Axis and germ line deficiencies caused by u.v. irradiation of Xenopus oocytes cultured in vitro
Authors: Holwill S. , Heasman J. , Crawley C. R. , Wylie C. C. 
Published: April 2021

ABSTRACT
An intriguing aspect of developmental biology is the extent to which early development is controlled by the spatial arrangement of molecules in the oocyte. Ultraviolet (u.v.) irradiation of the vegetal pole of the fertilized egg of Xenopus laevis affects both the development of the embryonic dorsal axis and also the formation of primordial germ cells (PGCs). However, the importance of cytoplasmic localization in the oocyte has been difficult to assess because, until recently, it has proved impossible to mature and fertilize cultured oocytes routinely.
In this report, we describe a method for routinely maturing and fertilizing cultured oocytes of Xenopus. We find that the u.v.-sensitive period for PGC and dorsal axis formation extends back into stage-VI oocytes, thus demonstrating a true oocyte contribution to these processes. This method also allows greater time for experimental intervention and should facilitate the eventual isolation of the molecules concerned.
The development of animal cap cells in Xenopus: the effects of environment on the differentiation and the migration of grafted ectodermal cells
Authors: Jones E. A. , Woodland H. R. 
Published: April 2021

ABSTRACT
We have used blastocoel and vegetal pole grafts to investigate the effect of environment on differentiation and movement of animal pole cells of Xenopus. In the blastocoel of embryos earlier than stage 10, fragments of animal pole primarily form mesoderm. The cells are either integrated into normal host tissues or they organize a secondary posterior dorsal axis. If either host or graft is later than stage 9 the graft forms ectoderm and its cells all migrate into the host ectoderm. Inner layer animal cells form sensorial layer; outer cells move to the epidermis. Thus considerable powers of appropriate movement are seen. In the vegetal pole no movement occurs. If the graft is stage 9 or earlier, or the host is stage 10| or earlier, the graft forms mesoderm, including striated muscle in the gut. This shows that muscle can develop in wholly the wrong environment, it suggests that the dorsal inductive signal from mesoderm is rather general in the vegetal mass and suggests that dorsal mesoderm development involves little subsequent adjustability. If the host is stage 11 or later, or the graft later than stage 9, the graft forms epidermis in the gut. This shows that the epidermal pathway of development is also insensitive to environment.
Distribution of yolk polypeptides in the follicle cells during the differentiation of the follicular epithelium in Sarcophaga bullata egg follicles
Authors: Geysen Johan , Cardoen Johan , Loof Arnold De 
Published: April 2021

ABSTRACT
In S. bullata, the ovaries contribute to the synthesis of yolk polypeptides. A specific antiserum for yolk polypeptides was used to visualize the presence of yolk polypeptides in the follicle cells during their differentiation. After vitellogenesis has started, all follicle cells contain yolk polypeptides. The squamous follicle cells covering the nurse cells and the border cells lose yolk polypeptides before mid-vitellogenesis, whereas the follicle cells over the oocyte contain yolk polypeptides until after late vitellogenesis. All follicle cells are immunonegative afterwards. In vitro translation of poly(A)+ RNA demonstrated that the presence of yolk polypeptide mRNA correlates well with follicle cell immunopositivity for yolk polypeptides. This suggests that the follicle cells synthesize the ovarian yolk polypeptides. Differences in cellular and nuclear morphology, total and poly(A)+ RNA synthesis and the rate of yolk polypeptide synthesis were shown to be correlated with the presence or absence of yolk polypeptides in the differentiating follicular epithelium. The possible relationship between these different aspects of follicle cell differentiation, follicle cell polyploidy and the extracellular current pattern around follicles are discussed.
Ultrabithorax gene expression in Drosophila imaginal discs and larval nervous system
Authors: Brower Danny L. 
Published: April 2021

ABSTRACT
Using a monoclonal antibody and image-processing procedures, the patterns of expression of the Ultrabithorax (Ubx) gene product have been characterized in Drosophila larvae. As reported previously, the metathoracic imaginal discs stain most intensely with anti-Ubx, with some mesothoracic and no prothoracic expression detectable. In the metathoracic discs, the greatest modulation in anti-Ubx staining is along the proximodistal axis. Ubx is generally expressed at higher levels in the posterior regions of metathoracic discs, although relatively high anterior expression is found in some areas. Expression in the mature wing disc is confined to the squamous peripodial membrane cells; in younger wings, Ubx expression fills the posterior half of the peripodial side of the disc. The mesothoracic leg stains with a pattern that is qualitatively similar (but not identical) to that of the metathoracic leg; Ubx is expressed in some anterior regions of the mesothoracic leg, in parasegment 4. Double staining with anti-Ubx and anti-engrailed reveals that discontinuities in Ubx expression that have been suggested to correspond to compartment borders do not coincide with the compartment boundaries in some cases. In the larval ventral ganglion, Ubx expression is greatest in parasegments 5 and 6, as in the embryonic nervous system.
Nerve-dependent accumulation of myosin light chain 3 in developing limb musculature
Authors: Merrifield Peter A. , Konigsberg Irwin R. 
Published: April 2021

ABSTRACT
Myosin alkali light chain accumulation in developing quail limb musculature has been analysed on immunoblots using a monoclonal antibody which recognizes an epitope common to fast myosin light chain 1 (MLCif) and fast myosin light chain 3 (MLC3f). The limb muscle of early embryos (i.e. up to day 10 in ovo) has a MLC profile similar to that observed in myotubes cultured in vitro-, although MLC)r is abundant, MLC3r cannot be detected. MLC3f is first detected in 11-day embryos. To determine whether this alteration in MLC3f accumulation is nerve or hormone dependent, limb buds with and without neural tube were cultured as grafts on the chorioallantoic membrane of chick hosts. Although differentiated muscle develops in both aneural and innervated grafts, innervated grafts contain approximately three times as much myosin as aneural grafts. More significantly, although aneural grafts reproducibly accumulate normal levels of MLCif, they fail to accumulate detectable levels of MLC3f. In contrast, innervated grafts accumulate both MLCif and MLC3f, suggesting that the presence of neural tube in the graft promotes the maturation, as well as the growth, of muscle tissue. This is the first positive demonstration that innervation is necessary for the accumulation of MLC3f that occurs during normal limb development in vivo.
Immunolocalization of three oocyte nuclear proteins during oogenesis and embryogenesis inPleurodeles
Authors: Abbadie C. , Boucher D. , Charlemagne J. , Lacroix J. C. 
Published: April 2021

ABSTRACTThe location of three proteins of the oocyte nucleus of Pleurodeles was studied during oogenesis and embryogenesis using monoclonal antibodies A33/22, C3/1 and C36/1. Immunoblotting of two-dimensional gel electophoregrams of oocyte nuclear proteins showed that these antibodies recognized proteins whose relative molecular masses and isoelectric points were 80X103 and 6 4, 175×103 and 5 and 270×103 and 7, respectively. In the oocyte, all three proteins were nucleoplasmic; those revealed by antibodies A33/22 and C36/1 were detected on lampbrush chromosomes: the first one on the RNP matrix of the loops, and the second one on both the loops and the chromomeres. Protein A33/22 was observed in most nuclei during embryonic, larval and adult development, except for the young embryo, before the midblastula transition. The distribution of this protein in the oocyte and its behaviour during development suggest that it might be involved in the packaging of RNAs during transcription. Antibody C3/1 recognized an oocyte nucleoplasmic protein with biochemical and biophysical properties similar to those of protein N1-N2, After oocyte maturation, the protein moved into the cytoplasm of the animal hemisphere and, from fertilization to the midblastula stage, it shifted from the cytoplasm into the nuclei as cell division proceeded. Starting from the gastrula stage, this protein became specific to the endoderm nuclei. After hatching, it was no longer detectable. This behaviour seems to correspond to that of a nuclear protein issued from the maternal stock pile. Protein C36/1 behaved similarly during early development, but remained in most nuclei after neurulation until the adult age, with a pattern similar to that of protein A33/22. In addition, it was present on the mitotic chromosomes. Its association with mitotic as well as lampbrush chromosomes connects it with the DNP fibre proteins.
Avoidance of posterior tectal membranes by temporal retinal axons
Authors: Walter Jochen , Henke-Fahle Sigrid , Bonhoeffer Friedrich 
Published: April 2021

ABSTRACT
Membrane carpets consisting of alternating membrane stripes were prepared from plasma membranes of anterior and posterior chick optic tectum. Axons from retinal explants extend neurites on these carpets. Axons of the nasal retina do not distinguish between the stripes. Axons of the temporal retina prefer to extend neurites on anterior tectal membranes.
Treatment of the membrane fragments with high temperature interferes with the pattern of neurite outgrowth from temporal axons. When growing on carpets consisting of treated anterior and posterior tectal membranes, temporal retinal axons no longer distinguish between the stripes. Treatment of posterior membranes alone is sufficient to abolish the preference of temporal axons to extend neurites on anterior tectal membranes. Treatment of the anterior membranes alone has no effect.
This result is best explained by a repulsive component in the posterior tectal membranes. Temporal, but not nasal, axons specifically recognize and avoid that component, with the result that they do not extend neurites on posterior tectal membrane stripes. Once the repulsive component is destroyed, temporal axons are able to extend neurites on posterior tectal membranes.
Expression and segregation of nucleoplasmin during development in Xenopus
Authors: Litvin Judith , King Mary Lou 
Published: April 2021

Abstract
The spatial segregation of informational molecules in the unfertilized egg and embryo has been hypothesized to be a necessary phenomenon for the normal pro-gression of development leading to the determination of cellular phenotypes. This study describes the selec-tion of a monoclonal antibody (Mab:2G6) that ident-ifies an antigen (Ag:2G6) which is localized in the germinal vesicle of oocytes and has a discrete pattern of inheritance during embryogenesis. The antigen displayed biochemical and physical characteristics very similar to nucleoplasmin, which is the histone-binding and nucleosome-assembly protein previously described. Immunoblot analysis with purified oocyte nucleoplasmin confirmed this relationship.
Indirect immunofluorescence was used to study the temporal expression and spatial distribution of nucleo-plasmin. From early cleavage stages through gastru-lation, it is preferentially localized in nuclei of blasto-meres at the animal pole. By tadpole stages, it was detected only in nuclei of postmitotic cells of the central nervous system and in nuclei of striated muscle. It was not detected in adult tissues. Western blot analysis during embryogenesis revealed at least five immunologically related polypeptides that dis-played distinct patterns of expression during develop-ment. The different species observed most likely represent different levels of phosphorylation of nu-cleoplasmin. The more acidic forms, known to be more active in nucleosome assembly, were present during cleavage stages.
Analysis of labelled oocyte proteins by two-dimen-sional immunoblots and autoradiography revealed that synthesis of nucleoplasmin was first detected in stage-2 oocytes, reached 60 % maximum levels at stage 3, peaked at stage 4 and was undetectable in stage-6 oocytes. The amount of nucleoplasmin message pres-ent does not follow a similar pattern during oogenesis. These results suggest that the message undergoes pronounced changes in translational efficiency during oogenesis.
A comparative immunoblot analysis using proteins from a variety of adult tissues revealed that, whereas the polyclonal antisera against amphibian vitellogenic oocyte nucleoplasmin recognized several different, tissue-specific polypeptides, two different monoclonal antibodies (Mab:b7-1D1, Mab:2G6) failed to recog-nize any of the adult tissues tested. We conclude that nucleoplasmin is a family of closely related proteins with distinct embryonic and adult members.