bluuebunny/crossref_metadata_2025_split huggingface dataset:
Induction of labial expression in the Drosophila endoderm: response elements for dpp signalling and for autoregulation
Authors: Tremml Gabi , Bienz Mariann 
Published: April 2021

ABSTRACT
Extracellular signal proteins induce the homeotic gene labial (lab) to high levels of localised expression in the endoderm of Drosophila embryos. We aimed to identify cis-regulatory elements within the lab gene that respond to this induction by analysing the activity of stably integrated reporter gene constructs. Dissection of lab 5 flanking sequences reveals two types of response elements. One of these mediates lab dependent activity, providing evidence that lab induction in the endoderm is autoregulatory. The other element, to a large extent independent of lab function, responds to decapentaplegic (dpp), a signal molecule related to mammalian TGF-. Our evidence suggests that lab induction in the endoderm reflects coordinate action of two distinct factors one of which may be lab protein itself, and another whose localised activity or expression in the midgut depends on the dpp signal.
Molecular gradients along the proximal-distal axis of embryonic insect legs: possible guidance cues of pioneer axon growth
Authors: Norbeck Betty A. , Feng Yun , Denburg Jeffrey L. 
Published: April 2021

ABSTRACT
It has been proposed that gradients of environmental cues direct the proximal growth of pioneer axons in embryonic insect legs. Hybridoma techniques have been used to produce 3 monoclonal antibodies (mAbs) that bind to components associated with the basal lamina/extracellular matrix that are non-uniformly distributed along the proximal-distal axis of cockroach legs at the time of pioneer axon growth. Two of these mAbs, PROD-1 and PROD-2, label the proximal parts of the leg more intensely than the distal ends. The other mAb, DIP-1, has the reverse pattern of binding with the distal parts of the leg labeled more intensely. The graded distribution of these antigens only occurs just prior to and during the growth period of the Ti1 pioneer axons. Western blot analyses and immunoprecipitations have identified the protein antigens recognized by these mAbs. The spatial and temporal distributions of these molecules in the legs and the CNS make them good candidates for environmental guidance cues of pioneer axon growth.
Ontogeny of calbindin-D28K and calbindin-D9K in the mouse kidney, duodenum, cerebellum and placenta
Authors: Shamley D. R. , Opperman L. A. , Buffenstein R. , Ross F. P. 
Published: April 2021

ABSTRACT
The appearance of the calcium-binding proteins (CaBP-D28K and CaBP-D9K) in embryonic mice tissues was determined using a sensitive immunohistochemical assay. CaBP-D28K first appears in myenteric nerve plexuses of the duodenum on day E15, in duodenal villus cells on day E16, in Purkinje cells of the cerebellum on day E19, in cells of the mesonephric duct on day E11 and in the metanephric duct on day E12. CaBP-D9K first appears in enterocytes of the duodenum on day E18, in trophoblastic giant cells (TGC) of the placenta on day E10, and in the metanephric duct on day E15. A differential time of appearance and colocalization of the two CaBPs is demonstrated in the embryonic mouse kidney, suggesting either that vitamin D does not control both CaBPs in the foetus or that the vitamin D control is unequal. The early appearance and location of CaBP-D9K in TGCs may suggest that these cells play an important role in transplacental transfer of calcium.
Differential screening of a PCR-generated mouse embryo cDNA library: glucose transporters are differentially expressed in early postimplantation mouse embryos
Authors: Smith David E. , Gridley Thomas 
Published: April 2021

ABSTRACT
Differential screening of a cDNA library constructed using PCR amplification techniques from RNA isolated from the distal portion (embryonic ectoderm, mesoderm and visceral endoderm) of 7.5 days post coitum (dpc) mouse embryos led to the isolation of two cDNA clones expressed at higher levels in 7.5 dpc embryos than 12.5 dpc embryos. Nucleotide sequence analysis revealed that each of these clones was a different member of the family of facilitative glucose transporters (Glut genes). The differentially expressed cDNA clones represent mouse Glut-1 and Glut-3. Levels of the Glut-3 mRNA declined 14-fold between days 7.5 and 12.5 of gestation, and were under our limits of detetction by 14.5 dpc. The levels of the Glut-1 mRNA declined about 3-fold between days 7.5 and 12.5 of gestation.
Analysis of the expression of these genes by in situ hybridization revealed striking differences in transcript localization in early postimplantation mouse embryos. At 7.5 dpc, both transporters were expressed more strongly in extraembryonic tissues than in the embryo proper. While both transporters were expressed in the amnion and chorion, only Glut-1 was expressed in the ectoplacental cone. In the yolk sac, Glut-3 appeared to be expressed only in the endoderm while Glut-1, although expressed in both layers, was expressed more strongly in the mesoderm layer. Thus, the two transporters have relatively reciprocal sites of expression in the developing extraembryonic membranes. Expression of Glut-1 was fairly widespread in the embryo at 8.5 dpc, but by 10.5 dpc expression was down-regulated and was observed in the eye and the spinal cord. Expression of Glut-3 was largely confined to non-neural surface ectoderm and was also substantially down-regulated by 10.5 dpc.
These results prompted an examination of the RNA expression pattern of two other glucose transporter isoforms, Glut-2 and Glut-4. We did not detect Glut-4 expression, while Glut-2 expression was largely confined to extraembryonic visceral yolk sac endoderm. These data suggest differential roles for these glucose transporter family members during early postimplantation development of mice.
Expression of Pax-3- and neuroectoderm-inducing activities during differentiation of P19 embryonal carcinoma cells
Authors: Pruitt Steven C. 
Published: April 2021

ABSTRACT
A P19 embryonal carcinoma stem cell line carrying an insertion of the E. coli LacZ gene in an endogenous copy of the Pax-3 gene was identified. Expression of the Pax-3/LacZ fusion gene in neuroectodermal and mesodermal lineages following induction of differentiation by chemical treatments (retinoic acid and dimethylsulfoxide) was characterized using this line and is consistent with the previous localization of Pax-3 expression in the embryo to mitotically active cells of the dorsal neuroectoderm and the adjacent segmented dermomyotome. Pax-3/LacZ marked stem cells were also utilized as target cells in mixing experiments with unmarked P19 cells that had been differentiated by pretreatment with chemical inducers. Induction of -galactosidase and neuroectodermal markers in the target cells demonstrates that: (1) some differentiated P19 cell derivatives transiently express endogenous Pax-3- and neuroectoderm-inducing activities, (2) undifferentiated target stem cells respond to these activities even in the presence of leukemia inhibitory factor and (3) the endogenous activities can be distinguished from, and are more potent than, retinoic acid treatment in inducing neuroectoderm. These observations demonstrate that P19 embryonal carcinoma cells provide a useful in vitro system for analysis of the cellular interactions responsible for neuroectoderm induction in mammals.
Expression of α1 integrin, a laminin-collagen receptor, during myogenesis and neurogenesis in the avian embryo
Authors: Duband Jean-Loup , Belkin Alexey M. , Syfrig Josef , Thiery Jean Paul , Koteliansky Victor E. 
Published: April 2021

ABSTRACT
In this study, we have examined the spatiotemporal distribution of the 1 integrin subunit, a putative laminin and collagen receptor, in avian embryos, using immunofluorescence microscopy and immunoblotting techniques. We used an antibody raised against a gizzard 175 × 103Mr membrane protein which was described previously and which we found to be immunologically identical to the chicken α1 integrin subunit. In adult avian tissues, α1 integrin exhibited a very restricted pattern of expression; it was detected only in smooth muscle and in capillary endothelial cells. In the developing embryo, α1 integrin subunit expression was discovered in addition to smooth muscle and capillary endothelial cells, transiently, in both central and peripheral nervous systems and in striated muscles, in association with laminin and collagen IV. α1 integrin was practically absent from most epithelial tissues, including the liver, pancreas and kidney tubules, and was weakly expressed by tissues that were not associated with laminin and collagen IV. In the nervous system, 1 integrin subunit expression occurred predominantly at the time of early neuronal differentiation. During skeletal muscle development, α1 integrin was expressed on myogenic precursors, during myoblast migration, and in differentiating myotubes. α1 integrin disappeared from skeletal muscle cells as they became contractile. In visceral and vascular smooth muscles, α1 integrin appeared specifically during early smooth muscle cell differentiation and, later, was permanently expressed after cell maturation. These results indicate that (i) the expression pattern of α1 integrin is consistent with a function as a laminin/collagen IV receptor; (ii) during avian development, expression of the α1 integrin subunit is spatially and temporally regulated; (iii) during myogenesis and neurogenesis, expression of α1 integrin is transient and correlates with cell migration and differentiation.
A new member of the spectrin superfamily may participate in the formation of embryonic muscle attachments in Drosophila
Authors: Volk Talila 
Published: April 2021

ABSTRACT
Myotube migration and the formation of muscle attachments are crucial events for the proper development of muscle patterning in the Drosophila embryo. This paper describes the identification of a new embryonic muscle-specific protein, MSP-300, in Drosophila. This protein is initially expressed by muscle precursors at muscle-ectoderm and muscle-muscle attachment sites. As development continues, MSP-300 becomes associated with muscle myofibrillar network. Studies of the subcellular localization of this muscle-specific protein in primary embryonic cultured myotubes show that MSP-300 dec- orates actin filaments, and that it is specifically enriched in sites where actin microfilaments are linked to the plasma membrane. Migrating myotubes exhibit high levels of this protein at their leading edge while, in myotubes that have already developed sarcomeric architecture, the protein is localized mainly at the Z-discs. Sequence of a partial 3.9 kb cDNA clone and molecular analysis of the predicted protein sequence of this protein indicates that it encodes a high relative molecular mass protein (∼300×103), which exhibits at least five spectrin-like repeats. Several properties are shared by MSP-300 and members of the spectrin superfamily: it is associated with actin microfilaments, its sequence exhibits spectrin-like repeats and it is localized at sites where actin is linked to the plasma membrane. This protein could have a developmental role in the formation of muscle-ectoderm attachments and may be involved in myotube migration on the ectoderm.
Connectin, a target of homeotic gene control in Drosophila
Authors: Gould Alex P. , White Robert A. H. 
Published: April 2021

ABSTRACT
The homeotic genes of Drosophila encode transcription factors that specify morphological differences between segments. To identify the genes that they control, we developed a chromatin immunopurification approach designed to isolate in vivo binding sites for the products of the homeotic gene Ultrabithorax. Here, we report the analysis of one immunopurified binding site. This 110 bp fragment maps within a regulatory region of a gene under homeotic control, connectin. A 4 kb DNA fragment, including the immunopurified binding site, is suf-ficient to reproduce the appropriate homeotic control within a subset of the full tissue distribution of connectin. Analysis of the role of the 110 bp binding site indicates that it mediates transcriptional controls by Ultrabithorax and other homeotic genes. This is the first report of a functional in vivo binding site isolated using the chromatin immunopurification method. We also show that the protein product of the connectin gene is predicted to be a cell-surface molecule containing leucine-rich repeats. The protein, connectin, can mediate cell-cell adhesion thus suggesting a direct link between homeotic gene function and processes of cell-cell recognition.
The 412 retrotransposon and the development of gonadal mesoderm in Drosophila
Authors: Brookman Jenny J. , Toosy Ahmed T. , L. S. Shashidhara , A. H.White Robert 
Published: April 2021

ABSTRACT
We have shown that the expression of the 412 retrotransposon provides a useful early marker for the development of the gonadal mesoderm in Drosophila embryos. 412 is initially expressed in a set of parasegmentally repeated stripes from parasegments (PS) 2-14 in the mesoderm at the extended germ band stage. During germ band retraction the bulk of 412 expression declines except in dorsolateral clusters of cells in PS10, 11 and 12, where high levels of 412 expression remain. These mesodermal cell clusters are associated with germ cells and subsequently they coalesce, rounding up to form the gonads. The gonadal mesoderm thus appears to originate specifically from three abdominal parasegments, PS10, 11 and 12. We show that the maintenance of high levels of 412 expression in gonadal mesoderm is not induced by contact with germ cells, but rather depends on genetic control by the homeotic genes abdominal-A and Abdominal-B.
Drosophila homologs of two mammalian intracellular Ca2+-release channels: identification and expression patterns of the inositol 1,4,5- triphosphate and the ryanodine receptor genes
Authors: Hasan Gaiti , Rosbash Michael 
Published: April 2021

ABSTRACT
We have identified and cloned portions of two Drosophila genes homologous to two classes of mam- malian intracellular Ca2+-release channels, the ryan- odine receptor and the inositol 1,4,5-triphosphate (IP3) receptor. The Drosophila ryanodine receptor gene (dry) encodes an approx. 15 kb mRNA. It is expressed in the mesoderm of early stage-9 embryos and subsequently in somatic muscles and their precursor cells. In adults, dry mRNA was detected in tubular muscles and at a lower level in neuronal tissues. Embryonic expression of the Drosophila IP3 receptor gene (dip) appears more dynamic and is associated with developing anterior sense organs. In adults, dip expression occurs in several tissues, and relatively high levels of dip mRNA in adult antennae suggest a role for this gene product during olfactory transduction.
Muscle gene activation in Xenopus requires intercellular communication during gastrula as well as blastula stages
Authors: Gurdon J. B. , Kao K. , Kato K. , Hopwood N. D. 
Published: April 2021

ABSTRACT
In Xenopus an early morphological marker of mesodermal induction is the elongation of the mesoderm at the early gastrula stage (Symes and Smith, 1987). We show here that the elongation of equatorial (marginal) tissue is dependent on protein synthesis in a mid blastula, but has become independent of it by the late blastula stage. In animal caps induced to become mesoderm, the time when protein synthesis is required for subsequent elongation immediately follows the time of induction, and is not related to developmental stage. For elongation, intercellular communication during the blastula stage is of primary importance.
Current experiments involving cell transplantation indicate a need for further cell:cell interactions during gastrulation, and therefore after the vegetal-animal induction during blastula stages. These secondary cell interactions are believed to take place among cells that have already received a vegetal induction, and may facilitate some of the later intracellular events known to accompany muscle gene activation.
Retinoic acid and the late phase of neural induction
Authors: Sharpe C. R. 
Published: April 2021

ABSTRACT
Regional neural gene expression in Xenopus is the result of a number of processes that continue well beyond the end of gastrulation. By considering two of the basic features of neural induction, the duration of contact between mesoderm and ectoderm and the timing of neural competence, it has been possible to distinguish two phases in neural tissue formation. The late phase includes the period following gastrulation.
A factor in determining regional neural gene expression is the difference in inducing ability of the mesoderm that develops during gastrulation along the anterior-posterior axis. The resulting ability to express regional neural genes is subsequently refined during the late phase by a signal that progresses from the posterior part of the embryo. Using a dorsal explant system, it is shown that this progressive signal can be mimicked by the addition of retinoic acid (RA). However, the observation that regions along the anterior-posterior axis respond in different ways to the addition of RA suggests that additional factors are also important in defining regional neural gene expression. One possibilty is that the expression of retinoic acid receptors along the axis may demarcate regions that respond to RA in particular ways.
Cell interactions and mesodermal cell fates in the sea urchin embryo
Authors: Ettensohn Charles A. 
Published: April 2021

ABSTRACT
Cell interactions during gastrulation play a key role in the determination of mesodermal cell fates in the sea urchin embryo. An interaction between primary and secondary mesenchyme cells (PMCs and SMCs, respectively), the two principal populations of mesodermal cells, regulates the expression of SMC fates. PMCs are committed early in cleavage to express a skeletogenic phenotype. During gastrulation, they transmit a signal that suppresses the skeletogenic potential of a subpopulation of SMCs and directs these cells into an alternative developmental pathway. This review summarizes present information concerning the cellular basis of the PMC-SMC interaction, as analyzed by cell transplantation and ablation experiments, fluorescent cell labeling methods and the use of cell type-specific molecular markers. The nature and stability of SMC fate switching, the timing of the PMC-SMC interaction and its quantitative characteristics, and the lineage, numbers and normal fate of the population of skeletogenic SMCs are discussed. Evidence is presented indicating that PMCs and SMCs come into direct filopodial contact during the late gastrula stage, when the signal is transmitted. Finally, evolutionary questions raised by these studies are briefly addressed.
An analysis of Abdominal-B expression in the locust Schistocerca gregaria
Authors: Kelsh Robert , Dawson Iain , Akam Michael 
Published: April 2021

ABSTRACT
We have cloned a homologue of the homeotic gene Abdominal-B from the locust Schistocerca gregaria and raised antibodies against the homeodomain and C-terminal flanking region of the encoded protein. This antibody stains the posterior abdomen of the developing Schistocerca embryo from 26% of development onwards, a stage when only the anterior of the abdomen is visibly segmented. By the time segmentation has reached the posterior of the abdomen, ABD-B protein is detectable only in the terminal segment (A11). Expression extends anteriorly as development proceeds to include the epidermis of all segments from A8p to A11, including the genital appendages of A9 and A10. The anal cerci, generally regarded as appendages of A11, remain unstained. This expression domain corresponds to the region within which the Abd-B r function of the Drosophila Abd-B gene is expressed. We detect no expression corresponding to the Abd-B m function in Drosophila.
Mutations of the fizzy locus cause metaphase arrest in Drosophila melanogaster embryos
Authors: Dawson Iain A. , Roth Siegfried , Akam Michael , Artavanis-Tsakonas Spyros 
Published: April 2021

ABSTRACT
We describe the effects of mutations in the fizzy gene of Drosophila melanogaster and show that fizzy mutations cause cells in mitosis to arrest at metaphase. We show that maternally supplied fizzy activity is required for normal nuclear division in the preblastoderm embryo and, during later embryogenesis, that zygotic fizzy activity is required for the development of the ventrally derived epidermis and the central and peripheral nervous systems. In fizzy embryos, dividing cells in these tissues arrest at metaphase, fail to differentiate and ultimately die. In the ventral epidermis, if cells are pre-vented from entering mitosis by using a string mutation, cell death is prevented and the ability to differentiate ventral epidermis is restored in fizzy;string double mutant embryos. These results demonstrate that fizzy is a cell cycle mutation and that the normal function of the fizzy gene is required for dividing cells to exit metaphase and complete mitosis.
Functional and molecular characterization of the transcriptional regulatory region of Tcp-10bt, a testes-expressed gene from the t complex responder locus
Authors: Ewulonu U. Kevin , Buratynski T. J. , Schimenti John C. 
Published: April 2021

ABSTRACT
Mouse t haplotypes contain several mutant alleles that disrupt spermatogenesis. Their phenotypes include sterility, reduced fertility and transmission ratio distortion (TRD). The substantial genetic analyses of these mutant alleles, coupled with intensive physical characterization of the t complex, provides a fertile ground for identifying and understanding genes essential to male gametogenesis. The t complex responder (Tcr) locus plays a central role in this process, interacting with other t haplotype-encoded genes to mediate TRD. A candidate responder gene, Tcp-10bt, has been cloned and subjected to molecular characterization. Here, we define the transcriptional regulatory regions of this gene in transgenic mice. A 1.6 kb (but not 0.6 kb) DNA fragment upstream of the transcription start site contains all the regulatory signals for appropriate temporal and germ cell-specific expression of this gene. Two smaller fragments within this region bound specifically to nuclear factor(s) from germ cell protein extracts in gel shift assays. This work is a step towards understanding the mechanism of Tcp-10bt regulated expression and may ultimately help reveal a common regulatory pathway shared by other similarly expressed spermatogenic genes.
Changing patterns of gene expression define four stages of cerebellar granule neuron differentiation
Authors: Kuhar Siobhan G. , Feng Lei , Vidan Susana , Ross M. Elizabeth , Hatten Mary E. , Heintz Nathaniel 
Published: April 2021

ABSTRACT
Among CNS neuronal populations, the cerebellar granule cell provides a simple model for analysing the molecular regulation of CNS neurogenesis. In this study, polyclonal antisera raised against immature granule cell precursors, purified from early postnatal mouse cerebellum, were used to isolate 39 unique cDNA clones from a gt11 cDNA expression library made from the same cell population. Northern blot analysis revealed developmental stage and tissue-specific expression of 28 of the clones. In situ localization of mRNAs encoded by these novel cDNAs, as well as those encoding the axonal glycoprotein TAG-1 and the 6 subunit of the GABAA receptor, reveal four distinct stages in cerebellar granule cell differentiation. The developmentally transient and spatially restricted expression of clones GC9 and GC44 identify a previously unrecognized step in cerebellar histogenesis.