pinecone/core-2020-05-10-deduplication huggingface dataset:
Regulation of Nuclear Envelope Assembly/Disassembly by MAP Kinase

AbstractMouse eggs arrested in metaphase II display high levels of cdc2/cyclin B1 and MAP protein kinase activities. Following fertilization there is a time-dependent decrease in the activity of each of these protein kinases. The decline in cdc2/cyclin B1 protein kinase correlates with the resumption of meiosis and the emission of the second polar body and precedes the decline in MAP kinase activity, which correlates temporally with the formation of the male and female pronuclear envelopes. These results suggest that high levels of MAP kinase activity are incompatible with the presence of a pronuclear envelope. To test this possibility, we expressed in mouse eggs a constitutively active form of MAP kinase kinase (MEK) whose only known target is p42/p44 MAP kinase. We show that following fertilization cdc2/cyclin B1 kinase activity declines and a second polar body is emitted. The endogenous MAP kinase remains active, however, and no pronuclear envelopes form. Thus, high levels of MAP kinase activity by itself in mouse eggs appear incompatible with the presence of a pronuclear envelope
Cardiovascular Lesions and Skeletal Myopathy in Mice Lacking Desmin

AbstractIn order to further our understanding of the biological role of desmin, the muscle-specific intermediate filament protein, a null mutation in the desmin gene was introduced into the germ line of mice. Despite the complete lack of desmin, these mice developed and reproduced. Since we show that skeletal, cardiac, and smooth muscles form in theDes−/−mice, it is reasonable to propose that desmin is not essential for myogenic commitment or for myoblast fusion or differentiationin vivo.However, morphological abnormalities were observed in the diaphragm of adult mice; these were demonstrated by disorganized, distended, and nonaligned fibers. The heart presented areas of hemorrhaging in which fibrosis and ischemia were observed. We have also shown that the absence of desmin produces specific defects in smooth muscles. In conclusion, our results have demonstrated that desmin is not required for the differentiation of skeletal, cardiac, and smooth muscles but is essential to strengthen and maintain the integrity of these tissues
Development of the Indirect Flight Muscle Attachment Sites inDrosophila:Role of the PS Integrins and thestripeGene

AbstractUsing markers that are expressed at muscle attachment sites, we have examined the early pupal development (first 36 hr) of Indirect Flight Muscle (IFM) attachments in the fruit flyDrosophila melanogaster.Expression of theDrosophilahomologs of vertebrate integrins, the Position-Specific (PS) antigens, is known to differentially mark epidermal (PS1α) and muscle (PS2α) components of the developing IFM attachment sites. During myogenesis, PS2α is detected transiently in imaginal myoblasts that fuse with persistent larval muscles to give rise to the Dorsal Longitudinal Muscles (DLMs), but not in myoblasts that fusede novoto give rise to the DorsoVentral Muscles. The integrins are not expressed at attachment sites when the muscle fibers first make their appearance (12–20 hr). Following muscle–epidermal contact, PS1 and PS2 are detected at muscle attachment sites. PS1 expression is at the muscle ends and also in the long epidermal processes that connect the developing muscle fibers to their sites of attachment in the epidermis, while PS2 expression is restricted to the muscle ends. Epidermal cells that will contribute to the adult attachment sites are defined as early as the third larval instar. Both anterior and posterior sites of attachment of the IFMs are marked by the expression of reporter β-galactosidase activity in a P-element line B14.0, which is an insertion at thestripelocus. B14.0 (stripe) is seen in distinct domains in the wing and leg imaginal discs which give rise to the thoracic cuticle. The expression is maintained during pupal development. The B14.0 (stripe) expressing epidermal cells contact the developing muscle fibers, leading to the formation of the myotendon junction. We show that the dorsal and ventral attachment sites of one group of IFMs, the DVMs arise from two different imaginal discs (wing and leg, respectively), which may explain the differential effect of mutations such asbendlesson these muscles. Attachment sites for the other group of IFMs, the DLMs, on the other hand, arise from one imaginal disc (wing). B14.0 (stripe) expression defines epidermal cells of the adult attachment sites and is likely to function during early events leading to the formation of muscle–epithelial contacts. The PS integrins are detected at later stages, suggesting a role in the stabilization and maturation of the muscle–epidermal contacts into myotendon junctions
Morphological and Molecular Characterization of Retinoic Acid-Induced Limb Duplications in Mice

AbstractThis study reports a morphological, skeletal, and molecular characterization of the supernumerary limbs induced by systemic administration of all-transretinoic acid to egg-cylinder stage mouse embryos. As initially described by Rutledgeet al.(Proc. Natl. Acad. Sci. USA91, 5436, 1994), we have found that oral administration of all-transretinoic acid (70 mg/kg body weight) at 5.5 days postcoitum induced the formation of supernumerary limbs. Most often, these arose as a pair of extra buds located caudally and ventrally to the normal (orthotopic) hindlimb buds without duplication of the lower body axis. The resulting one or two supernumerary hindlimbs were connected to an imperfectly mirror-image-duplicated pelvic girdle. Variable truncations of the stylopodium and zeugopodium skeleton, as well as abnormal splitting of the distal skeleton, were frequently observed. The apical ectodermal ridge of the extra limb buds expressed expected growth factor genes. However, an ectopic anterior expression ofSonic hedgehogandHoxd-13was seen in the supernumerary buds, suggesting that these buds would incorporate potential polarizing cells of the hindlimb or genital field and generate an ectopic polarizing zone. This is consistent with the reverse orientation of most supernumerary limbs at later stages. Some of the buds did not express limb-specific markers and were thus expected to degenerate or form nonlimb structures, as observed in an adult specimen. Less frequently, extra limb buds with normal polarity were associated to a duplicated lower body axis. Retinoic acid also generated a novel type of duplication in which “twin” hindlimbs with two parallel apical ectodermal ridges and zones of polarizing activity arose on one side of the embryo
Fertilization inDrosophila melanogaster:Centrosome Inheritance and Organization of the First Mitotic Spindle

AbstractMicrotubule, chromatin, centrosome, and nuclear envelope configurations during the first division of theDrosophila melanogasterzygote were analyzed in order to investigate the organization of the first cleavage spindle and the origin of the functional centrosome. After pronuclear apposition the parental complements congress at the equatorial plane of the metaphase spindle. The chromatids, however, seem to move to the poles in two separate groups in each half spindle, mingling together during telophase, before the formation of the daughter nuclei. The spatial separation of parental complements during the first mitosis is also supported by the behavior of the nuclear envelope of female and male pronuclei. A low frequency of polyspermy is also observed during fertilization inD. melanogaster
Multiple Roles for Dopamine inDrosophilaDevelopment

AbstractManipulation of dopamine levels by inhibition of tyrosine hydroxylase activity was accomplished inDrosophila melanogasterlarval instars by feeding enzyme inhibitors for a 24-hr period. Behavioral assays performed immediately after treatment demonstrated that larval phototaxis, salt aversion, and heptanol preference were unaffected by reduced levels of dopamine. Within a few hours of treatment, the larvae ceased exploratory behavior and were unresponsive to external stimuli; these larvae eventually died. This behavior is strikingly similar to that displayed by dopamine-deficient transgenic mice. Treated larvae placed immediately onto normal food (to replenish dopamine levels) showed significant developmental delays and decreased fertility as adults. The lethality, developmental retardation, and decrease in fertility were reversed by addition ofL-DOPA to inhibitor-containing food, suggesting that these effects were due solely to inhibition of tyrosine hydroxylation. Depletion of dopamine in newly eclosed females resulted in abnormally developed ovaries. These results suggest that the enzymatic function of tyrosine hydroxylase is vital and that reduced levels of dopamine result in akinesia and lethality, developmental retardation, and decreased fertility
Gain-of-Function Alleles ofBeardedInterfere with Alternative Cell Fate Decisions inDrosophilaAdult Sensory Organ Development

AbstractWe have isolated a novel class of gain-of-function mutations at theBearded(Brd) locus which specifically affect the development of adult sensory organs inDrosophila.TheseBrdalleles cause bristle multiplication and bristle loss phenotypes resembling those described for the neurogenic genesNotch(N) andDelta(Dl). We have found that supernumerary sensory organ precursor (SOP) cells develop in the proneural clusters ofBrdmutant imaginal discs; like normal SOPs, these are dependent on the function of the proneural genesachaeteandscute,and express elevated levels of ac protein. At cuticular positions exhibiting theBrdbristle loss phenotype, we have found that the progeny of the multiplied SOPs develop aberrantly, in that neurons and thecogen (sheath) cells appear but not trichogen (shaft) and tormogen (socket) cells. This appears to represent a transformation of the pIIa secondary precursor cell within the SOP lineage to a pIIb secondary precursor cell fate. These results suggest thatBrdgain-of-function alleles interfere withNotchpathway-dependent cell–cell interactions at two distinct stages of adult sensory organ development. We have also identified enhancers and suppressors of theBrddominant phenotypes; these include both previously characterized mutations and alleles of apparently novel loci. Finally, we have found thatBrdnull mutants are viable and exhibit no mutant phenotypes, suggesting thatBrdmay be a component of an overlapping function
Sp4, a Member of the Sp1-Family of Zinc Finger Transcription Factors, Is Required for Normal Murine Growth, Viability, and Male Fertility

AbstractWe report the cloning, characterization, and targeting of an Sp1-related zinc finger transcription factor gene from the distal arm of mouse chromosome 12. This gene, previously identified in rats and humans and designatedsp4,is homologous to theDrosophila buttonhead(btd) gene, which is expressed in the head region of developing flies. Similarly,in situhybridizations show thatsp4is highly expressed in mouse embryos in the developing central nervous system (CNS). Expression ofsp4is seen as early as Day 9 of development, where transcripts are abundant in the posterior neuropore. Expression in later embryos is detected throughout the CNS as well as in other structures, including the nasal mucosa, the vomeronasal organ, the epithelium of the lung and intestinal tract, the testes, and the developing teeth. Northern blot analysis showedsp4expression in the adult brain and other tissues. Gene targeting by homologous recombination was used to determine the role ofsp4during mouse development. Two-thirds of homozygous mutants die within the first few days after birth and those that survive are smaller than their wild-type littermates. While fertility of the female mutants appears normal, homozygous mutant males do not breed, despite having histologically intact testes containing mature sperm.sp4/sp4mutant males fail to copulate, indicating that this gene is required for normal male reproductive behavior
Control of Epitheliomesenchymal Transformation II. Cross-Modulation of Cell Adhesion and Cytoskeletal Systems in Embryonic Neural Cells

AbstractProtein kinase (PK) inhibitors like staurosporine induce precocious epitheliomesenchymal transformation (EMT) of quail embryo neuralanlagencultured on the extracellular matrix (ECM) molecule fibronectin (Newgreen and Minichiello,Dev. Biol.170, 91–101; 1995). We show here that this also occurs on laminin, vitronectin, and collagen type I and type IV, but not on polylysine or BSA. In the absence of cell–ECM adhesion, staurosporine produced a rapid increase in, rather than a loss of, cohesion in isolated neuralanlagenand increased the rate of reaggregation of dissociated neural cells. In the absence of cell–cell adhesions (i.e., with dissociated cells), almost all neural cells rapidly adhered to fibronectinin vitroand staurosporine made only a marginal difference to this. Almost no neural cells spread on fibronectin in control conditions but staurosporine stimulated spreading by almost all cells. When cell–cell adhesions were present, neuralanlageexplants were more difficult to dislodge by controlled shear from fibronectin substrates in the presence of staurosporine than under control conditions, but in both experiments and controls dislodgment was due to the cell bodies breaking proximal to the cell–fibronectin adhesion sites. EMT in neural cells in culture, both spontaneous and induced by staurosporine, involved rapid reduction in circumferential F-actin fibers and an increase in pancytoplasmic G-actin, as shown by fluorescent phalloidin and DNase I labeling. Loss of immunoreactivity for N-cadherin at cell–cell junctions also occurred in both spontaneous and induced EMT. However, in spontaneous EMT the cadherin changes preceded the actin changes, whereas in induced EMT, the reverse occurred. The results suggest that the molecules involved in EMT which are affected by PK inhibitors are cytoskeletal and link elements. These results also suggest that balanced cross-modulation among cell–cell adhesion molecules, cell–ECM adhesion molecules, and cytoskeletal molecules can trigger and orchestrate EMT, without direct genetic supervision
Multiplecis-Acting Elements Act Cooperatively in Directing Trochoblast-Specific Expression of the α-tubulin-4 Gene inPatellaEmbryos

AbstractDuring early embryogenesis of the molluscPatella vulgatathe α-tubulin-4 gene is specifically expressed in the differentiation process of a particular cell type, the trochoblasts. The 5′ region of the gene has been analysed for elements that are required for the regulation of the cell-type-specific activation of the gene. In a functional assay, seven elements that play a role in the spatiotemporal activation of the gene were detected in the promoter sequence. They are not required all together at the same time. A core of two elements, together with two or three auxiliary elements, are sufficient in controlling trochoblast-specific expression of the gene in thePatellaembryo. One of the core elements is always required, without it, the gene is not expressed at all. The other core element acts as a positive element in trochoblasts and as a negative element in non-trochoblasts and thus is involved in directing the cell-type specificity of expression. The seven elements act cooperatively, and at least some of them can substitute for each other. Sequence comparison revealed that six of the seven fragments contain the sequence element GTTAA, including one of the core elements. Both core elements seem to play a crucial role in the expression of the α-tubulin-4 gene during the differentiation process of trochoblasts in thePatellaembryo. A model for the regulation of the cell-type specificity of the gene during trochoblast differentiation is proposed
Functional Equivalence and Rescue Among Group 11HoxGene Products in Vertebral Patterning

AbstractHoxa-11andHoxd-11are paralogous genes required for proper development of the vertebral column, the limbs, and the urogenital system. To further explore the functional relationship between these genes, as well as the potential rescue of one function by the other, we have introduced aHoxd-11-expressing transgene intoHoxa-11/Hoxd-11mutant genetic backgrounds. A range of phenotypes was observed, with transgenic mice displaying as few as four lumbar vertebrae while double mutant mice had as many as eight. When transgenic, double homozygote mutant animals showed six lumbar vertebrae, instead of the eight usually observed. The phenotypic rescue of these genotypes shows that theHoxa-11andHoxd-11products are functionally equivalent and that extra doses ofHoxd-11can rescueHoxa-11loss of function
A Switch inBroad-ComplexZinc-Finger Isoform Expression Is Regulated Posttranscriptionally during the Metamorphosis ofDrosophilaImaginal Discs

AbstractTheBroad-Complex(BR-C) is a key member of the 20-hydroxyecdysone regulatory hierarchy that coordinates changes in gene expression duringDrosophilametamorphosis. The family of transcription factors encoded by theBR-Cshare a common amino-terminal domain which is fused by alternative splicing to one of four pairs of C2H2zinc-finger domains (Z1, Z2, Z3, and Z4). In this study, we examine the temporal expression of transcripts encoding eachBR-Czinc-finger isoform—including the newly discovered fourth zinc-finger domain—during the metamorphosis of imaginal discs which form the integumental structures of the adult head and thorax. We find that allBR-Czinc-finger RNA isoforms are induced as a primary response to 20-hydroxyecdysone. However, inducedBR-CRNA isoforms exhibit two divergent expression profiles. The Z2, Z3, and Z4 RNA isoforms accumulate to high levels at the beginning of the ecdysone response and abruptly disappear after several hours. In contrast, the Z1 RNA isoform continues to accumulate while the others decline, resulting in a switch in relative isoform levels. Using probes specific to different regions of theBR-C,we show that the switch inBR-CRNA isoform expression appears to be posttranscriptionally regulated, presumably by ecdysone-responsive factors. We propose that this switch results from a change in splice acceptor site choice. Finally, we present a model describing how this temporal switch in isoform expression could mediate changes inBR-Cfunction, from transcriptional activation to repression and vice versa, that are critical for coordinate downstream target gene expression
Determination of Neuroepithelial Cell Fate: Induction of the Oligodendrocyte Lineage by Ventral Midline Cells and Sonic Hedgehog

AbstractNear the floor plate of the embryonic neural tube there is a group of neuroepithelial precursor cells that are specialized for production of the oligodendrocyte lineage. We performed experiments to test whether specification of these neuroepithelial oligodendrocyte precursors, like other ventral neural cell types, depends on signals from the notochord and/or floor plate. We analyzed heterozygous Danforth's short tail (Sd/+) mutant mice, which lack a notochord and floor plate in caudal regions of the neural tube, and found that oligodendrocyte precursors did not appear at the ventricular surface where there was no floor plate. Moreover, oligodendrocytes did not develop in explant cultures ofSd/+ spinal cord in the absence of a floor plate. When a second notochord was grafted into an ectopic position dorsolateral to the endogenous notochord of a chicken embryo, an additional floor plate was induced along with an ectopic focus of oligodendrocyte precursors at the ventricular surface. Oligodendrocytes developed in explants of intermediate neural tube only when they were cocultured with fragments of notochord or in the presence of purified Sonic hedgehog (Shh) protein. Thus, signals from the notochord/floor plate, possibly involving Shh, are necessary and sufficient to induce the development of ventrally derived oligodendroglia. These signals appear to act by specifying the future fate(s) of neuroepithelial cells at the ventricular surface rather than by influencing the proliferation or differentiation of prespecified progenitor cells in the parenchyma of the cord
Investigation of Developing Embryonic Morphology Using Optical Coherence Tomography

AbstractImproved imaging of morphological changes has the potential of offering new insight into the complex process of embryonic development. Optical coherence tomography (OCT) is a new imaging technique for performingin vivocross-sectional imaging of architectural morphology by measuring backscattered infrared light. This study investigates the application of OCT for imaging developing structure inRana pipiens, Xenopus laevis,andBrachydanio rerio.Images are compared to conventional histological baselines. Cross-sectional imaging can be performed and structural morphology identified at greater imaging depths than possible with confocal and light microscopy. Repeated OCT imaging may be performedin vivoin order to track structural changes throughout development
The Expression of Brachyury (T) during Gastrulation in the Marsupial FrogGastrotheca riobambae

AbstractGastrulation in the marsupial frogGastrotheca riobambaehas been analyzed by the distribution of the Brachyury (T) protein. Comparison with other amphibians provides mechanistic insights, sinceG. riobambaedevelops slowly and has the most divergent mode of amphibian gastrulation, producing an embryonic disk. The T pattern indicates that the prospective mesoderm is superficial, as in many amphibians. The dorsal blastopore lip could not be identified by the expression ofT, or by morphological criteria, thus it is unknown whetherGastrothecaembryos have a dorsal organizer before or after blastopore closure. The circumblastoporal and notochordal expression ofT, which are temporally contiguous inXenopus,are separated inGastrotheca,implying that distinct regulatory mechanisms may control the expression ofTin its two domains. The separation of the T pattern also indicates that involution at the blastopore is separate from notochord formation. In addition, extension of the archenteron and notochord occurs after blastopore closure, suggesting that dorsal convergence and extension have been delayed until after blastopore closure. Therefore, dorsal convergence and extension need not be the cause of blastopore closure inGastrotheca.The separation of gastrulation events in embryos that have not been experimentally manipulated, such as those ofGastrotheca,helps in understanding the distinct nature of gastrulation processes
Disperse versus Compact Elements for the Regulation ofruntStripes inDrosophila

AbstractThe segmented body pattern of theDrosophilaembryo is established through a hierarchical network of interacting genes. At each successive step in this pathway, transcriptional regulation is used to convert coarse positional information into finer patterns of gene expression. Central to this process are thecis-regulatory regions that drive the dynamic spatial expression of the different segmentation genes. Here we describe thecis-regulatory region of theruntgene. As found for both other primary pair-rule genes,hairyandeven-skipped,there are stripe-specific elements which mediate the initial regulation ofruntstripes by gap genes. We did not find autoregulatory elements as described foreven-skippedandfushi tarazu.The regulation ofruntby other pair-rule genes is mediated by a large region, extending over 5 kb upstream and downstream of the transcription start site. This “disperse” element cannot be subdivided into functionally independent subelements or minimal elements. Such disperse elements mediating pair-rule gene interactions may have escaped detection in other segmentation genes and may involve molecular mechanisms different from those mediating regulation by gap genes