bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential co-expression of long and short form type IX collagen transcripts during avian limb chondrogenesis in ovo
Authors: Swiderski Ruth E. , Solursh Michael 
Published: April 2021

Abstract
Using RNA blot analysis of developmentally staged avian limb buds, we demonstrate that transcripts of several cartilage marker genes appear in limb tissue prior to overt chondrogenesis. Type II collagen mRNA, cartilage proteoglycan core protein mRNA, α2(IX) collagen mRNA, and transcripts of the short form α1(IX) collagen chain derived from the downstream promoter are co-expressed in limb tissue approximately 24–36 hours before the appearance of the respective polypeptides in differentiating cartilagenous tissue. Transcripts of the long form α1(IX) collagen chain derived from the upstream promoter appear somewhat later in development; nearly coincident with the immunolocalization of type IX collagen in the cartilage elements of the limb. The spatial distribution of type n and type IX collagen transcripts was analyzed by in situ hybridization. Type II collagen and the long form α1(IX) collagen transcripts co-localized in the chondrogenic elements of the developing forelimb. In contrast, short form α1(IX) collagen transcripts which lack the 5’ region encoding the NC4 globular amino-terminal domain were distributed throughout the non-chondrogenic, non-myogenic mesenchymal regions of the limb and were not detectable above background levels in the limb chondrogenic elements. The precocious appearance of several cartilage marker gene transcripts prior to chondrogenesis suggests that multiple levels of gene regulation including alternative promoter use, alternative RNA splicing, alternative poly adenylation, and other post-transcriptional as well as translational mechanisms are active prior to, and during avian limb chondrogenesis.
β-D xyloside alters dermatan sulfate proteoglycan synthesis and the organization of the developing avian corneal stroma
Authors: Hahn Rita A. , Birk David E. 
Published: April 2021

Abstract
Corneal transparency is dependent upon the development of an organized extracellular matrix containing small diameter collagen fibrils with regular spacing, organized as orthogonal lamellae. Proteoglycan-collagen interactions have been implicated in the regulation of collagen fibrillogenesis and matrix assembly. To determine the role of dermatan sulfate proteoglycan in the development and organization of the secondary corneal stroma, its synthesis was disrupted using β-D xyloside. The secondary corneal stroma contains two different proteoglycans, dermatan sulfate and keratan sulfate proteoglycan. β-D xyloside interferes with xylose-me-diated O-linked proteoglycan synthesis, and thus disrupts dermatan sulfate proteoglycan synthesis. Corneal keratan sulfate proteoglycan, a mannose-mediated N-linked proteoglycan, should not be altered. Biochemical analysis of corneas treated both in vitro and in ovo revealed a reduced synthesis of normally glycosylated dermatan sulfate proteoglycans and an increased synthesis of free xyloside-dermatan sulfate glycosaminoglycans. Keratan sulfate proteoglycan synthesis was unaltered in both cases. Corneal stromas were studied using histochemistry and electron microscopy after in ovo treatment with β-D xyloside. The observed biochemical alterations in dermatan sulfate proteoglycans translated into disruptions in the organization of β-D xyloside-treated stromas. There was a reduction in the histochemical staining of proteoglycans, but no alteration in collagen fibril diameter. In addition, focal alterations in collagen fibril packing, and a disruption of lamellar organization were observed in β-D xyloside-treated corneas. These data suggest that dermatan sulfate proteoglycans are not involved in the regulation of corneal collagen fibril diameter, but are important in the fibril-fibril spacing as well as in lamellar organization, and cohesiveness.
The Drosophila retinoid X receptor homolog ultraspiracle functions in both female reproduction and eye morphogenesis
Authors: Oro Anthony E. , Mckeown Michael , Evans Ronald M. 
Published: April 2021

Abstract
ultraspiracle (usp) encodes the Drosophila cognate of RXR, the human retinoid X receptor. To examine how RXR subfamily members function in development, we have undertaken a phenotypic analysis of usp mutants. usp is required at multiple stages of development for functions that occur in a wide variety of tissues, usp is required in the eye-antennal imaginal disc for normal eye morphogenesis and in the somatic and germline tissues of adult females for fertilization, eggshell morphogenesis and embryonic development. An unusual sunken eye phenotype with marked ventral-dorsal polarity appears to be caused by a lack of usp function in the imaginal disc cells that reside between the eye and antennal anlage. The usp functions include cell autonomous and non-cell autonomous components, suggesting that usp controls the production of factors important for both cell-cell communication and cellular differentiation. These usp signalling pathways have mechanistic parallels to steroid and retinoid action in developing vertebrate tissues.
Gynandromorphs of Drosophila suggest one common primordium for the somatic cells of the female and male gonads in the region of abdominal segments 4 and 5
Authors: Szabad János , Nöthiger ROLF 
Published: April 2021

Abstract
In mosaic gonads of gynandromorphs of Drosophila, the amount of female and the amount of male somatic tissues add up to roughly one unit. This suggests that the somatic component of the gonads in males and females derives from a single common primordium, i.e. testes and ovaries appear to be homologous. Fate-mapping places this primordium ventrally of the sternites into the mesodermal region of the fourth and fifth abdominal segment. This location is corroborated by the observation that defects in and around abdominal segment 4 and absence of the gonads are strongly correlated in animals damaged by the mutation osk301. Gonads were mosaic with a frequency of 10.5% which indicates that the gonadal primordium originates from about 10 progenitor cells, and together with other evidence, suggests that these progenitor cells are located within a single segment (or parasegment).
Imprinting of phosphoribosyltransferases during preimplantation development of the mouse mutant, Hprtb-m3
Authors: Moore T. F. , Whittingham D. G. 
Published: April 2021

ABSTRACT
The measurement of the activity of the X-linked enzyme HPRT has been widely used as an indicator of X-chromosome activity during preimplantation development in the mouse. More recently, the concomitant measure-ment of the activity of the autosomally-encoded enzyme APRT has been used in an attempt to decrease the variability inherent in the measurement of enzyme activity from minute samples such as preimplantation embryos.
In this study the use of the HPRT-deficient mouse mutant, Hprtb-m3, allowed the unequivocal identification of the parental origin of HPRT activity measured in embryos derived from crosses between wild-type mice, and mice which were homozygous or hemizygous for the Hprtb-m3 allele. Results were similar to those of a previous study, where oocyte-encoded HPRT activity accounted for about 10% of total HPRT activity at 76 hours post human chorionic gonadotrophin injection and the paternally-derived Hprt allele was shown to be transcriptionally active by the late 2-cell stage.
In contrast to other studies, differential expression of the two Hprt alleles was detected during the preim-plantation period, in embryos derived from crosses between wild-type and HPRT-deficient mice. Evidence was also found for the existence of an X-linked locus which influences the amount of APRT activity in the unfertilized oocyte. We propose that the expression pat-tern of this locus may be influenced by its parental origin.
The role of the teashirt gene in trunk segmental identity in Drosophila
Authors: Röder Laurence , Vola Christine , Kerridge Stephen 
Published: April 2021

ABSTRACT
The phenotypes of different mutant combinations of teashirt (tsh) and homeotic genes together with their regulatory interactions are described in order to gain insight into tsh gene function. We show that when tsh, Scr, Antp and BX-C genes are missing, the ventral part of the trunk (or thorax and abdomen) is transformed to anterior head identity showing that tsh is a homeotic gene. These genes act synergistically to suppress the expression of the procephalic gene labial (lab) in subsets of cells in each segment of the trunk. Transcripts from the tsh gene always accumulate in segments destined to acquire trunk identities. tsh gene activity is required for the normal function of the Antp and BX-C genes, which modulate in part the expression of tsh. As a whole, our results suggest that tsh plays an essential dual role, during embryogenesis, for determining segmental identity of the trunk. First, tsh is required critically for the identity of the anterior prothorax. Second, tsh is required globally for segmental identity throughout the entire trunk whereas the “classical” homeotic genes have more specific roles. Our results are consistent with the idea that tsh is defining the ground state of the Drosophila trunk region seen in the absence of the Antp and BX-C genes.
Perturbation of developmental gene expression in rat liver by fibric acid derivatives: lipoprotein lipase and α-fetoprotein as models
Authors: Staels Bart , Auwerx Johan 
Published: April 2021

ABSTRACT
Liver lipoprotein lipase (LPL) and α-fetoprotein (AFP) gene expression show similar developmental patterns. Both mRNAs are abundantly expressed in neonatal rat liver and gradually disappear upon ageing. Treatment with fibric acid derivatives, such as fenofibrate, not only delays the developmental extinction of the LPL gene, but also increases LPL mRNA levels in neonatal rat liver. Similarly, the developmental extinction of the AFP gene in the liver is clearly delayed after fenofibrate. In adult rat liver, fibric acid derivatives transcriptionally reinduce a mRNA with similar size as LPL, but no effect on AFP mRNA was detected. Sequence comparison of clones isolated from a fenofibrate-induced cDNA library demonstrates that the fenofibrate-(re)induced mRNA in adult rat liver is encoding for LPL. The induction of LPL after fenofibrate is tissue-specific, since heart and adipose tissue LPL mRNA levels remain unchanged. In conclusion, fibric acid derivatives modulate develop-mental expression patterns in rat liver, and may selec-tively reinduce the expression of extinct genes in adult rat liver.
Inhibin α- and βA -subunit immunoreactivity in the chicken embryo during morphogenesis
Authors: Bläuer Merja , Kohonen Juhani , Leivonen Ilkka , Vilja Pekka , Tuohimaa Pentti 
Published: April 2021

ABSTRACT
Antibodies against synthetic peptides selected from the amino acid sequences of human inhibin α- and β β β A-subunits were used to examine the distribution of inhibin subunit immunoreactivity in chicken embryos during the first week of development. Inhibin α.-subunit immunoreactivity was localized in skeletal and smooth muscle myoblasts as well as developing cardiac muscle cells. In somites, immunostaining was seen exclusively in myotomes. The appearance of α.-subunit immunore-activity was correlated with myogenic differentiation; immunoreactivity was not seen in non-differentiated mesenchymal cells or in terminally differentiated adult muscle cells. In cardiac muscle, some immunopositive myocytes were seen also in the adult. In the adult heart, the Purkinje fibers were strongly immunoreactive, suggesting a possible role of the immunoreactive protein in the impulse-conducting function of these specialized cells. Inhibin α.-subunit immunoreactivity was also seen in the visceral and parietal cells of the Bowman’s capsule in both mesonephric and metanephric kidneys. In addition to mesodermal derivatives, α.-subunit immunoreactivity was localized in neuroepithelial cells and axons in the developing central nervous system. Immunoblotting with anti-α.(1-32) revealed two protein bands with Mr values of 50 000 and 32 000 in cytosol samples of whole embryos under nonreducing conditions. In reduced samples an approximately 14 000 Mr protein species was detected.
Inhibin β A-subunit immunoreactivity was detected only in chondrocytes, suggesting that the immunoreactive protein might represent a chicken homologue of the various cartilage and bone morphogenetic proteins expressed in mammals.
Developmental modulation of myosin expression by thyroid hormone in avian skeletal muscle
Authors: Gardahaut M. F. , Fontaine-Perus J. , Rouaud T. , Bandman E. , Ferrand R. 
Published: April 2021

ABSTRACT
It is well established that a rise in circulating thyroid hormone during the second half of chick embryo development significantly influences muscle weight gain and bone growth. We studied thyroid influence on differentiation in slow anterior latissimus dorsi (ALD) and fast posterior latissimus dorsi (PLD) muscles of embryos rendered hypothyroid by hypophysectomy or administration of an anti-thyroid drug. The expression of native myosins and myosin light chains (MLCs) was studied by electrophoretic analysis, and the myosin heavy chain (MHC) was characterized by immunohistochemistry. The first effects of hypothyroid status were observed at day 21 of embryonic development (stage 46 according to Hamburger and Hamilton). Analysis of myosin isoform expression in PLD muscles of hypothyroid embryos showed persistence of slow migrating native myosins and slow MLCs as well as inhibition of neonatal fast MHC expression, indicating retarded differentiaton of this muscle. In ALD muscle, hypothyroidism maintained fast embryonic MHC and induced noticeable amounts of fast MLCs, thus delaying slow muscle differentiation. Our results suggest that thyroid hormones play a role in modulating the appearance of neonatal fast MHC and the disappearance of isomyosins transiently present during embryogenesis. However, T3 supplemental treatment would seem to compensate in part for the effects of hypothyroidism induced by hypophysectomy, suggesting that thyroid hormone might interfere with other factors also accounting for the observed effects.
Ventrolateral regionalization of Xenopus laevis mesoderm is characterized by the expression of α-smooth muscle actin
Authors: Saint-Jeannet Jean-Pierre , Levi Giovanni , Girault Jeanne-Marie , Koteliansky Victor , Thiery Jean-Paul 
Published: April 2021

ABSTRACT
Mesodermal patterning in the amphibian embryo has been extensively studied in its dorsal aspects, whereas little is known regarding its ventrolateral regionalization due to a lack of specific molecular markers for derivatives of this type of mesoderm. Since smooth muscles (SM) are thought to arise from lateral plate mesoderm, we have analyzed the expression of an - actin isoform specific for SM with regard to mesoderm patterning. Using an antibody directed against -SM actin that recognized specifically this actin isoform in Xenopus, we have found that the expression of -SM actin is restricted to visceral and vascular SM with a transient expression in the heart. The overall expression of the -SM actin appears restricted to the ventral aspects of the differentiating embryo. -SM actin expression appears to be activated following mesoderm induction in animal cap derivatives. Moreover, at the gastrula stage, SM precursor cells are regionalized since they will only differentiate from ventrolateral marginal zone explants. Using the animal cap assay, we have found that -SM actin expression is specifically induced in treated animal cap with bFGF or a low concentration of XTC-MIF, which induce ventral structures, but not with a high concentration of XTC-MIF, which induces dorsal structures. Altogether, these results establish that -SM actin is a reliable marker for ven-trolateral mesoderm. We discuss the importance of this novel marker in studying mesoderm regionalization.
Reorganization of the cytoskeleton during Drosophila oogenesis: implications for axis specification and intercellular transport
Authors: Theurkauf William E. , Smiley Scott , Wong Mei Lie , Alberts Bruce M. 
Published: April 2021

ABSTRACT
Inhibitor studies have implicated microtubules in at least three important developmental processes during Drosophila oogenesis: oocyte determination and growth during stages 1 through 6, positioning of the anterior determinant bicoid mRNA during stages 9 through 12, and ooplasmic streaming during stages 10b through 12. We have used fluorescence cytochemistry together with laser scanning confocal microscopy to identify distinct microtubule structures at each of the above three periods that are likely to be involved in these processes. During stages 1 through 7, maternal components synthesized in nurse cells are transported through cytoplasmic bridges to the oocyte. At this time, microtubules that appear to originate in the oocyte pass through these cytoplasmic bridges into the adjacent nurse cells; these microtubules are likely to serve as a polarized scaffold on which maternal RNAs and proteins are transported. During stages 7 and 8, microtubules in the oocyte cortex reorganize to form an anterior-to-posterior gradient, suggesting a role for microtubules in the localization of morphogenetic determinants. Finally, when ooplasmic streaming begins during stage 10 b, it is accompanied by the assembly of subsurface microtubule arrays that spiral around the oocyte; these arrays disassemble as the oocyte matures and streaming stops. During ooplasmic streaming, many vesicles are closely associated with the subsurface microtubules, suggesting that streaming is driven by vesicle translocation along microtubules. We believe that actin plays a secondary role in each of these morphogenetic events, based on our parallel studies of actin organization during each of the above stages of oogenesis.
Regional differences in retinoid release from embryonic neural tissue detected by an in vitro reporter assay
Authors: Wagner M. , Han B. , Jessell T. M. 
Published: April 2021

ABSTRACT
Retinoic acid and related retinoids have been suggested to contribute to the pattern of cell differentiation during vertebrate embryonic development. To identify cell groups that release morphogenetically active retinoids, we have developed a reporter assay that makes use of a retinoic acid inducible response element (RARE) to drive lacZ or luciferase reporter genes in stably transfected cell lines. This reporter gene assay allows detection of retinoids released from embryonic tissues over a range equivalent to that induced by femtomole amounts of retinoic acid. We have used this assay first to determine whether the floor plate, a cell group that has polarizing properties in neural tube and limb bud differentiation, is a local source of retinoids within the spinal cord. We have also examined whether the effects of exogenously administered retinoic acid on anteroposterior patterning of cells in the developing central nervous system correlate with differences in retinoid release from anterior and posterior neural tissue. We find that the release of morphogenetically active retinoids from the floor plate is only about 1.5-fold that of the dorsal spinal cord, which does not have neural tube or limb polarizing activity. These results suggest that the spatial distribution of retinoid release from spinal cord tissues differs from that of the neural and limb polarizing activity. This assay has also shown that retinoids are released from the embryonic spinal cord at much greater levels than from the forebrain. This result, together with previous observations that the development of forebrain structures is suppressed by low concentrations of retinoic acid, suggest that the normal development of forebrain structures is dependent on the maintenance of low concentrations of retinoids in anterior regions of the embryonic axis. This assay has also provided initial evidence that other embryonic tissues with polarizing properties in vivo release retinoids in vitro.
Mesoderm-inducing factors and the control of gastrulation
Authors: Smith J. C. , Howard J. E. 
Published: April 2021

ABSTRACT
One of the reasons that we know so little about the control of vertebrate gastrulation is that there are very few systems available in which the process can be studied in vitro. In this paper, we suggest that one suitable system might be provided by the use of mesoderm-inducing factors. In amphibian embryos such as Xenopus laevis, gastrulation is driven by cells of the mesoderm, and the mesoderm itself arises through an inductive interaction in which cells of the vegetal hemisphere of the embryo emit a signal which acts on overlying equatorial cells. Several factors have recently been discovered that modify the pattern of mesodermal differentiation or induce mesoderm from presumptive ectoderm. Some of these mesoderm-inducing factors will also elicit gastrulation movements, which provides a powerful model system for the study of gastrulation, because a population of cells that would not normally undertake the process can be induced to do so. In this paper, we use mesoderm-inducing factors to attempt to answer four questions. How do cells know when to gastrulate? How do cells know what kind of gastrulation movement to undertake? What is the cellular basis of gastrulation? What is the molecular basis of gastrulation?
Evolution of developmental decisions and morphogenesis: the view from two camps
Authors: Raff Rudolf A. 
Published: April 2021

ABSTRACT
Modern developmental biology largely ignores evolution and instead focuses on use of standard model organisms to reveal general mechanisms of development Evolutionary biologists more widely hold developmental biology to be of major consequence in providing potential insights into evolution. Evolutionary insights can enlighten our views of developmental mechanisms as much as developmental data offer clearer views of mechanisms which underlie evolutionary change. However, insights have been limited by the long-term disengagement of the two fields dating to the rise of experimental embryology in the 1890s. Molecular genetics now provides a powerful tool to probe both gene function and evolutionary relationships, and a greater connection has become possible. The expansion of experimental organisms beyond the standard model animals used in most studies of development allows us to ask deeper questions about the interaction of development and evolution. This paper presents an analysis of the complementary uses of the resulting data in the two fields as they grope for accommodation. Analysis of the radical changes in early develoment seen in closely related sea urchins with alternate modes of development illustrate the complementarity of developmental and evolutionary data. These studies show that what have been thought to be constrained mechanisms of axial determination, cell lineage patterning, and gastrulation in fact evolve readily and provide the means for the rapid evolution of development