bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ontogeny of immunoglobulin expression in the Mexican axolotl
Authors: Fellah Julien S. , Vaulot Daniel , Tournefier Annick , Charlemagne Jacques 
Published: April 2021

ABSTRACT
The ontogeny of immunoglobulin (Ig) synthesis was followed at both cellular and serological levels in the Mexican axolotl (Ambystoma mexicanum) using polyclonal antibodies recognizing all Ig molecules and a set of monoclonal antibodies (Mabs) specific for the Cμ and Cv heavy Ig chain isotypes and for the light chain constituents shared by IgM and IgY molecules. Clusters of IgM- and of IgY-synthesizing lymphocytes, often located in separate sites, are first present in spleen sections of 7-week-old 25 mm larvae, about one month after differentiation of the spleen anlage (stage 39–40). In 12-week-old 30–35 mm larvae, the relative proportion of IgM- and IgY-synthesizing cells in the spleen is the same as that in adult animals. However, a marked enhancement of the spleen B cell compartment occurs from 5 to 9 months when Ig-positive cells represent about 88 % of the lymphocyte population compared to 60 % in adults. No structures equivalent to B cell germinal centers were observed at any stage of the spleen differentiation and cells, although often clustered in small groups, remain dispersed in the entire organ. The relative proportions of IgM and IgY B cells throughout the spleen remain constant during development (about 1 IgY+ cell for 5–6 IgM+ cells) and IgM molecules are first detected in the serum of 2·5-month-old larvae. The enhancement of the serum IgM level correlates well with the absolute number of IgM+ cells in the growing spleen. IgY molecules cannot be detected in the serum before the 7th month but their level quickly increases to reach about 60 % of the adult value at 10 months. Thyroxine-induced metamorphosis or hyperimmunization of 4-to 6-month-old larvae had no effect upon the temporal expression of the Ig classes in serum.
Pigment pattern expression in the plumage of the quail embryo and the quail-chick chimaera
Authors: Richardson Michael K. , Hornbruch Amata , Wolpert Lewis 
Published: April 2021

ABSTRACT
The pattern of pigmentation in birds is dependent on the migration and differentiation of a population of neural crest cells that develop into melanoblasts. On the basis of previous grafting experiments Rawles (1948) concluded that the pigment pattern of the chimaera is determined by the genotype of the donor melanocyte. This led Wolpert (1981) to suggest that melanoblasts from one bird can read the positional value of the ectoderm in the feather papillae of another bird. An alternative view is that an isomorphic prepattern in the feathers determines the pigment pattern. We have examined these ideas in relation to the local pigment patterns of the embryonic quail wing, distal to the elbow, where several rows of feather papillae are consistently unpigmented.
Melanin pigment is first seen at stage 35. By stage 39 a characteristic pigment pattern has been established. Most of the dorsal feather papillae are heavily pigmented, whereas many ventral papillae are unpigmented. Of the ventral papillae three rows (E2, E3 and H2) are always unpigmented, and it is these three rows that form the basis of the quail local pattern. The DOPA reaction indicates that no melanoblasts are present in these white feathers, although they are present in all the feathers of the White Leghorn wing.
When quail neural crest cells are grafted to the chick, either isotopically or to the wing bud, all or nearly all rows of ventral papillae become pigmented by stage 39. The only evidence of donor influences in the pattern is that, in some grafts, rows E2–3 have a high proportion of unpigmented papillae, and wings from earlier stages resemble the quail. When unpigmented papillae are present, histology shows that they contain undifferentiated crest cells. When introduced into a quail wing bud, chick crest cells enter all the feather papillae of the wing, including those in rows E2–3 and H2.
We suggest that neither the positional information nor the prepattern theory alone can account for all of our findings. Contrary to previous claims, local cues may be important in determining crest-cell differentiation. We have established that crest cells migrate into all feather papillae of the quail-chick chimaera, including those that will remain unpigmented. We show that neither differential migration nor differential proliferation is involved in pattern formation in the quail-chick chimaera.
G-protein-linked signal transduction systems control development in Dictyostelium
Authors: Johnson R. L. , Gundersen R. , Lilly P. , Pitt G. S. , Pupillo M. , Sun T. J. , Vaughan R. A. , Devreotes P. N. 
Published: April 2021

ABSTRACT
G-protein-linked cAMP receptors play an essential role in Dictyostelium development. The cAMP receptors are proposed to have seven transmembrane domains and a cytoplasmic C-terminal region. Overexpression of the receptor in cells, when the endogenous receptor is not present, results in a 10- to 50-fold increase in cAMPbinding sites. Antisense cell lines, which lack cAMP receptors, do not enter the developmental program. Ligand-induced phosphorylation is proposed to occur on serine and threonine residues in the receptor C-terminus. The kinetics of receptor phosphorylation and dephosphorylation correlate closely with the shift of receptor mobility and the adaptation of several cAMP-induced responses. Two α-subunits, G-α-1 and G-α-2, have been cloned and specific antisera developed against each. Both subunits are expressed as multiple RNAs with different developmental time courses. The mutant Frigid A has a functional defect in G-α-2 which prevents it from entering development. We propose that G-protein-linked receptor systems will be a major component in the development of many organisms.
Determinative mechanisms in secondary muscle lineages of ascidian embryos: development of muscle-specific features in isolated muscle progenitor cells
Authors: Nishida Hiroki 
Published: April 2021

Abstract
Muscle cells of the ascidian larva originate from three different lines of progenitor cells, the B-line, A-line and b-line. Experiments with 8-cell embryos have indicated that isolated blastomeres of the B-line (primary) muscle lineage show autonomous development of a musclespecific enzyme, whereas blastomeres of the A-line and b-line (secondary) muscle lineage rarely develop the enzyme in isolation. In order to study the mechanisms by which different lines of progenitors are determined to give rise to muscle, blastomeres were isolated from embryos of Halocynthia roretzi at the later cleavage stages when conspicuous restriction of the developmental fate of blastomeres had already occurred. Partial embryos derived from B-line muscle-lineage cells of the 64-cell embryo (B7.4, B7.5 and B7.8) showed autonomous expression of specific features of muscle cells (acetylcholinesterase, filamentous actin and musclespecific antigen). In contrast, b-line muscle-lineage cells, even those isolated from the 110-cell embryo (b8.17 and b8.19), did not express any muscle-specific features, even though their developmental fate was mainly restricted to generation of muscle. Isolated A-line cells from the 64-cell embryos (A7.8) did not show any features of muscle differentiation, whereas some isolated A-line cells from the 110-cell embryos (A8.16) developed all three above-mentioned features of muscle cells. This transition was shown to occur during the eighth cell cycle. These results suggest that the mechanism involved in the process of determination of the secondary-lineage muscle cells differs from that of the primary-lineage muscle cells. Interaction with cells of other lineages may be required for the determination of secondary precursors to muscle cells.
The presumptive b-line and A-line muscle cells that failed to express muscle-specific features in isolation did not develop into epidermial cells. Thus, although interactions between cells may be required for muscle determination in secondary lineages, the process may represent a permissive type of induction and may differ from the processes of induction of mesoderm in amphibian embryos.
An extracellular matrix molecule of newt and axolotl regenerating limb blastemas and embryonic limb buds: immunological relationship of MT1 antigen with tenascin
Authors: Onda Hiroaki , Goldhamer David J. , Tassavat Roy A. 
Published: April 2021

Abstract
Several well-characterized extracellular matrix (ECM) components have been localized to the amphibian limb regenerate, but the identification and characterization of novel ECM molecules have received little attention. Here we describe, using mAb MT1 and immunocytochemistry, an ECM molecule expressed during limb regeneration and limb development. In limb stumps, mAb MT1 reactivity was restricted to tendons, myotendinous junctions, granules in the basal layers of epidermis, periosteum (newts) and perichondrium (axolotls). In regenerating limbs, reactivity in the distal limb stump was first detected 5 days and 1 day after amputation of newt and axolotl limbs, respectively. In both species, mAb MT1 recognized what appeared to be an abundant blastema matrix antigen, localized in both thin and thick cords between and sometimes closely associated with blastema cells. Reactivity was generally uniform throughout the blastema except for a particularly thick layer that was present immediately beneath the wound epithelium. During redifferentiation stages, mAb MT1 reactivity persisted among blastema cells and redifferentiating cartilage but was lost proximally in areas of muscle and connective tissue differentiation. During the entire period of embryonic limb development, mAb MT1 reactivity was seen in the ECM of the mesenchyme and in a layer beneath the limb bud ectoderm, similar to its distribution during regeneration. Considerable mAb MT1 reactivity was also associated with the developing somites. The reactivity of mAb MT1 in blastema and limb bud was similar if not identical to that of a polyclonal Ab against tenascin (pAbTN), a large, extracellular matrix glycoprotein implicated in growth control, inductive interactions, and other developmental events. This pAbTN effectively competed against mAb MT1 binding on blastema sections. In immunoblots, both mAb MT1 and pAbTN recognized a very high molecular weight (approximately Mr 1000 × 103) protein in blastema extracts of both newts and axolotls. mAb MT1 immunoprecipitated a protein of Mr 1000K size which reacted to both mAb MT1 and pAbTN in immunoblots. These data show that tenascin is in the matrix of the urodele blastema and limb bud, and suggest that mAb MT1 identifies urodele tenascin.
In vivo regulation of MPF in Xenopus oocytes
Authors: Johnson Andrew D. , Smith L. Dennis 
Published: April 2021

ABSTRACT
Entry into M phase in the eukaryotic cell cycle is controlled by the oscillating activity of MPF. The active component of MPF is now known to be the p34cdc2 protein kinase originally found in yeast. The p34cdc2 protein kinase displays a characteristic M-phase-specific histone Hl kinase activity when it interacts with cyclins, which are proteins that oscillate through the cell cycle and are thought to regulate p34cdc2 activity. Cyclins can induce M phase when introduced into fully grown Xenopus oocytes and cyclin may play a role in normal oocyte maturation. Small Xenopus oocytes do not mature in response to the hormonal triggers which act on stage 6 oocytes. We introduced cyclin into stage 4 (small) Xenopus oocytes and showed that it activates MPF in these cells, probably by interacting with endogenous p34cdc2 kinase. yye made labelled extracts from cyclin-mRNA-injected stage 4 oocytes and used them to show differential stability of clam cyclins A and B at oocyte maturation. The relative stability of the two forms of cyclin related directly to their ability to stabilize crude MPF preparations from injected stage 6 oocytes.
Patterns of tenascin expression during tail regeneration of the amphibian urodele Pleurodeles waltl
Authors: Arsanto Jean-Pierre , Diano Monique , Thouveny Yves , Thiery Jean Paul , Levi Giovanni 
Published: April 2021

ABSTRACT
We have determined the patterns of expression of tenascin, an extracellular matrix (ECM) glycoprotein, by indirect immunohistofluorescence and immunoblots during the post-traumatic regeneration of the tail distal part of the amphibian urodele Pleurodeles waltl. In normal tails of adult Pleurodeles, tenascin expression is mostly restricted to few connective tissues including the periosteum, the ligaments of vertebral articulation, myotendinous structures, the perimysium and the pia mater; the extracellular matrix is virtually negative. In certain areas of the adult skin the molecule is expressed around cells of the inner epidermal layer, apparently associated with the cell surface. In the first 4-6 days following tail amputation, tenascin expression increases in the stump region in areas surrounding dedifferentiating tendons; the early blastemic epithelium does not express the molecule. The local increase of tenascin in areas where cells dedifferentiate and start to migrate, precedes the increase in fibronectin that occurs later in the mesenchyme of the blastema. From the 8th day of regeneration, there is a sharp increase of the level of expression of the molecule in the extracellular matrix of the loose mesenchyme underlying the epithelium of the blastema which remains negative. The maximal expression in the matrix is reached in 4-to 6-week-old regenerates and then gradually decreased. High levels of tenascin are present in sites of muscle condensation as fibrils oriented parallel to the direction of alignment of myogenic cells and in sites of chondrogenesis particularly in regions of precartilage formation. After the second week of regeneration, tenascin is strongly expressed in the basal lamina of the regenerated skin and, after the fourth week, also at the level of epidermaldermal junctional areas. Like in normal tail ends, in regenerates older than 8 – 9 weeks, tenascin expression is nearly restricted to the muscle connective tissue and myotendinous structures.
These results are discussed in view of the possible multiple morphogenetic roles of tenascin in tissue regeneration and repair.
Molecular analysis of the Mov 34 mutation: transcript disrupted by proviral integration in mice is conserved in Drosophila
Authors: Gridley Thomas , Gray Douglas A. , Orr-Weaver Terry , Soriano Philippe , Barton David E. , Francke Uta , Jaenisch Rudolf 
Published: April 2021

ABSTRACT
The Mov 34 mutation is a recessive embryonic lethal mutation caused by retroviral integration in the murine germline. This integration disrupts a transcription unit that appears to encode a novel protein. The Mov 34 proviral integration is located on mouse chromosome 8 and the human homolog of this gene has been mapped to chromosome region 16q23-q24. An evolutionarily conserved syntenic relationship exists between this region of human chromosome 16 and a region of mouse chromosome 8 that also contains oligosyndactyly (Os), another recessive lethal mutation. Genetic studies have ruled out Os as residing at the same locus as the Mov 34 integration.
The Mov 34 transcript is conserved in evolution, and a Drosophila homolog appears to encode a protein with 62 % amino acid identity to the murine protein. In situ hybridization to Drosophila polytene chromosomes localizes the Drosophila homolog to 60B,C on chromosome 2. Several Drosophila lethal mutations also map to this region.
A positional marker for the dorsal embryonic retina is homologous to the high-affinity laminin receptor
Authors: Rabacchi Sylvia A. , Neve Rachael L. , Dräger Ursula C. 
Published: April 2021

ABSTRACT
In a search for determinants of positional information in the embryonic eye, we isolated two monoclonal anti bodies that label strongly the dorsal part of the undifferentiated embryonic retina in mammals, bird and cold blooded vertebrates. In the chick, the optic tectum is labeled in a corresponding fashion, the ventral tectum more heavily than the dorsal tectum. Through biochemical and molecular analysis both antibodies were found to recognize a protein that has been cloned repeatedly, first in a screen with antibodies to the ‘68K-laminin receptor’ (Wewer et al. (1986)Cancer Res. 47, 5691–5698), a name that may not exhaustively describe its function. Western blots show the protein to be present in most or all tissues, and Western and Southern blots reveal a high degree of conservation in the detected signals up to invertebrates and bacteria. Despite the very strong and selective labeling of the dorsal retina in conventional immunohistochemical preparations, the protein and its mRNA are present in even amounts throughout the embryonic retina, as demonstrated by Western and Northern blots of bisected retinas, and immunohistochemically in retinas fixed with ethylene glycole bissuccinimide (EGS), an NH2-group crosslinker with very long spacer arm. This indicates that the dorsoventral asymmetry in the embryonic retina is not in the amount but in the configuration of this protein; whether this difference relates to laminin binding is not known.
Early onset of phenotype and cell patterning in the embryonic zebrafish retina
Authors: Larison Karen D. , Bremiller Ruth 
Published: April 2021

ABSTRACT
The regular arrangement of retinal cone cells in a mosaic pattern is a common feature of teleosts. In the zebrafish, Brachydanio rerio, the retinal cone mosaic comprises parallel rows consisting of a repeating motif of four cone types. In order to elucidate the temporal and spatial aspects of the genesis of the cone mosaic in the developing retina, we generated a monoclonal antibody that specifically binds to the double cone photoreceptor of the adult. We first saw staining in the developing retina with this antibody, FRet 43, at 48 hours postfertilization, the time at which the first photoreceptor cells undergo their final mitotic division. We then injected embryonic fish with the thymidine analog, 5-bromo-2‘-deoxyuridine (BrdU), confirming with a double-labeling experiment that the onset of FRet 43 antigenicity occurs within three hours of the cellular division that generates the double cone photoreceptors. Then we stained tangential sections of the 54-hour embryonic retina with FRet 43, further showing that cells devoid of staining alternate with stained pairs of cells in a pattern that is consistent with the arrangement of photoreceptors in the adult cone mosaic. These results indicate that a marker of the double cone phenotype is expressed at approximately the same time as cellular birthday and that the mosaic patterning is present within 6 hours of this expression.
Experimental Studies on the Origin of the Cartilage of the Auditory Capsule and Columella in Ambystoma
Authors: Toerien M. J. 
Published: April 2021

ABSTRACT
The ear capsule chondrocytes are derived from three sources, viz. neural crest, ear placode and surrounding ectoderm, and also cranial mesentoderm. Under experimental conditions the crest ectomesenchyme is the least significant and the placode the most important source of cartilage cells. Ectomesenchyme of placodal origin predominates more often in capsules which developed into normal structures than in those that developed somewhat abnormally. The cartilaginous wall separating the internal ear from the brain is essentially of axial origin although it receives a contribution from the ecto-mesenchyme. Axial and capsular cartilage is separated along a fairly definite line ventral to the medial wall of the capsule. The presence or absence of the ear capsule affects the shape of the foot-plate of the columella, but not its existence. The footplate and stylus columellae share an origin with the visceral skeleton. The columella is most likely a part of the hyoid arch.
Environmental Factors Determining the Growth and Development of Whole Bone Transplants
Authors: Mawdsley R. , Harrison G. Ainsworth 
Published: April 2021

ABSTRACT
Intrinsic factors are known to play an integral part in skeletal morphogenesis (Willis, 1936; Fell, 1956). In particular, it has recently been demonstrated that the humerus (Felts, 1959) and femur (Chalmers & Ray, 1962) of the mouse develop, grow, and in many ways preserve their distinctive form when transplanted to non-functional sites. However, it is also widely recognized that internal and external environmental factors are important in determining skeletal growth and form (Sissons, 1956). The aim of this paper is to examine some of these extrinsic factors in terms of the effects of various types of host on the growth of subcutaneous transplants of the mouse humerus. The factors studied were environmental temperature, age and genotype including sex.
The Effects of Vitamin A and Citral on Epithelial Differentiation in vitro 2. The Chick Oesophageal and Corneal Epithelia and Epidermis
Authors: Aydelotte Margaret B. 
Published: April 2021

ABSTRACT
Differentiation of the oesophageal and corneal epithelia and epidermis of the chick embryo was studied in organ cultures in normal medium and in media containing added vitamin A and/or citral. In normal medium the oesophageal epithelium developed well for the first 6 days, but between 6 and 12 days many superficial layers of cells were sloughed and large mucous cells from the glands spread over the remaining epithelium. Vitamin A inhibited the normal stratification, and the oesophageal epithelium became pseudostratified and folded, with tall, columnar, ciliated cells and many small mucous glands. Citral inhibited the differentiation of ciliated and mucous cells and the epithelium became thicker than in normal medium. Vitamin A and citral together produced either a vitamin A or a citral effect, depending upon the relative concentrations of the two compounds. The corneal epithelium differentiated normally in the control cultures, but under the influence of additional vitamin A it remained thin and the superficial cells secreted mucus. In + citral medium the corneal epithelium became thicker than usual and the conjunctival epithelium keratinized. When both vitamin A and citral were added to the medium the corneal cultures showed a mild vitamin A effect. Skin cultures keratinized well in normal medium, but the epithelium remained thin and became mucus-secreting in response to high concentrations of vitamin A. Citral alone had little effect on epidermis, but it suppressed the vitamin A response almost completely when both compounds were added together. Citral produced changes resembling those of vitamin A deficiency in cultures of oesophagus and cornea, and it reduced the effects of added vitamin A. The results of these experiments therefore give further evidence of antagonism between vitamin A and citral. It is suggested that either deficiency of vitamin A or treatment with citral stimulates, whilst high concentrations of vitamin A inhibit, mitosis in the corneal epithelium. The results of these experiments indicate that each epithelium achieves its maximal synthesis of mucus at a characteristic concentration of vitamin A.