摘要:

AbstractIn the earlyXenopusembryo, a quadrant of endodermal cells that have descended from the vegetal dorsal localization in the zygote produces signals that pass into the animal hemisphere and induce dorsal mesoderm from the marginal zone. From the remaining three quadrants of the bordering endoderm, signals pass into the animal hemisphere and induce ventral mesoderm in the marginal region. There is evidence that suggests that these same mesoderm‐inducing signals continue through the plane of the tissue of the animal hemisphere where they may at least begin the processes of neural and epidermal induction by changing the competence of the prospective ectodermal cells, and possibly influencing the early regional biasing of later expression of at least some gene products, such as Epi‐1 whose expression in the future epidermal domain seems specified before gastrulation. We hypothesized that the interaction of the ventral and dorsal signals within the plane of the tissue of the animal hemisphere may position the border of the neural plate. If this is so, then transplantation into the animal pole of cells that signal induction of ventral mesoderm should drive the neural plate boundary back toward the blastopore and shorten the anterior‐posterior axis. Removal of cells that induce ventral mesoderm should result in an axis that is longer than normal. Results of our experiments support these predictions. Also, by late pregastrula stage 9, increasing the ventral signals has no effect. Thus the evidence suggests that the position of the anterior neural plate boundary is established before gastrulation begins by the interaction of the signals that induce the ventral and dorsal mesoderm. © 1993 wiley‐L

ISSN:1058-8388    

DOI:10.1002/aja.1001960202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe oncogeneGLIis amplified and expressed in some cases of human malignant glioma and undifferentiated childhood sarcoma a and is the prototype for a gene family characterized by a highly conserved set of five tandem zinc fingers and a consensus cysteine‐histidine link. This zinc finger motif has been shown to bind DNA with sequence specificity and may mediate transcriptional regulation. SinceGLIis expressed in embryonal carcinoma cell lines but not in most normal adult tissues and shows significant sequence similarity within its zinc finger domain tocubitus interruptus dominant(ciD), aDrosophilasegmentation gene known to be important in the morphogenesis of the posterior portion of each larval segment, we established the temporal and tissue expression patterns of the mouse homologue of humanGLIin day 10 through 18 mouse embryos with Northern blotting, reverse transcriptase coupled PCR, and in situ hybridization.glitranscripts were demonstrated on days 10 through 18 of mouse embryonic development as well as in normal adult uterus, brain, testis, and limb. Tissue expression ofgliduring gestation was demonstrated in Meckel's precartilage mesenchyme, the basis occipitus, rib mesenchymal condensations, primordial vertebral bodies, digital mesenchymal condensations in forefoot and hindfoot plates, the ependymal layer of the spnal cord, and the mesoderm of the gastrointestinal tract. Expression persisted throughout gestation in developing bone and cartilage of the extremities, the ribs, and the vertebral bodies, as well as the gastrointestinal tract mesoderm. These findings support a role forglifamily genes in normal craniofacial and digital development in mammals first suggested by the demonstration of translocation breakpoints within theGLI3gene in families with the Greig cephalopolysyndactyly syndrome and subsequently by reducedgli3expression in the mouse mutantextra toes. It is surprising that a single gene would be expressed in such a wide range of mesenchymal structures. © 1993 wiley‐Liss,

ISSN:1058-8388    

DOI:10.1002/aja.1001960203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractWe have studied the expression of phospholamban during the early development of chick embryos by in situ hybridization and have compared it to that of α‐cardiac and α‐skeletal actin. In adult cross‐striated muscles there is only one phospholamban gene and it is expressed exclusively in the heart and slow muscles. In the heart phospholamban transcripts were first detected at stage 14 in the region of presumptive ventricle and at stage 20 in the atrium. In the myotomal portion of the somites phospholamban mRNA was first detected at stage 20, which lagged behind the appearance of the α‐actins. In the limb rudiments all three mRNAs were barely detectable through stage 24, but increased by stage 28 +. However, quantitative analysis of signal intensity at stage 28 + indicated that less phospholamban mRNA is present in the limb bud than in the myotome since for phospholamban the ratio of the signal density in the myotome to that in the limb rudiments was about twice the value of the ratio determined for the α‐actins. Northern blot analysis of embryonic day 11 chick fast pectoralis muscle showed that phospholamban mRNA was not detected in vivo while α‐cardiac actin mRNA was. Moreover, no phospholamban mRNA was detected in primary cultures derived from pectoralis muscle of the same age. In concert with previous observations that phospholamban is not detectable at stage 30–32 in wing or thigh muscle, these results suggest that phospholamban mRNA is expressed independently of the α‐actins in the limb buds during early myogenesis.

ISSN:1058-8388    

DOI:10.1002/aja.1001960204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractChicken argininosuccinate lyase (ASL)/δ‐crystallin, a lens enzyme‐crystallin, is encoded in two linked genes (δ1 and δ2); only the δ2 polypeptide contains ASL activity. Here we have quantified δ1‐ and δ2‐crystallin mRNA in the lens, cornea, neural retina, heart, and brain at different stages of embryonic development and in 1‐wk‐old and 1‐yr‐old chickens by the polymerase chain reaction using internal δ1 and δ2 RNA standards. The δ1/δ2 mRNA ratio differed for every tissue and was regulated during development. In the embryo there was more δ1 than δ2 mRNA in the lens (50–100 times), cornea (3–4 times), and neural retina (2–20 times), about equal amounts of δ1 and δ2 mRNA in the heart, and more δ2 mRNA in the brain (15 times). δ1‐Crystallin mRNA differentially decreased in every tissue after hatching; by contrast, the δ2 mRNA remained about the same except for the lens, where it decreased 50‐fold between 1 wk and 1 yr after hatching. In the 1‐yr‐old chicken, the δ2/δ1 mRNA ratios were 7 in the lens, 175 in the cornea, 22 in the neural retina, 107 in the heart, and 136 in the brain, indicating that δ2‐crystallin is strongly favored in all adult tissues of the chicken. The excess of δ1 to δ2 mRNA in the embryonic lens, cornea, and neural retina is intriguing, and suggests some connection with developing transparent eye tissues. Finally, we raise the possibility that expression of both δ‐crystallin genes may create tetrameric ASL isoenzymes (perhaps with different specific activities). The unexpected predominance of δ2 mRNA in the 1‐yr‐old lens suggests that both the enzymatic and refractive functions of ASL/δ‐crystallin are operative and spatially separated, with the enzymatic role present in the cortical fibers and the r

ISSN:1058-8388    

DOI:10.1002/aja.1001960205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractDifferentiation of specific cell types during animal development can be detected by monitoring expression of appropriate genes. For this study, six different β‐galactosidase expression patterns which can be used as differentiation markers in the nematodeCaenorhabditis elegansare described. An earlier promoter trap screen identified pools of recombinant plasmids which gave patterns of β‐galactosidase expression when used to transformC. elegans.Each recombinant plasmid contained a random fragment ofC. elegansgenomic DNA fused upstream of a promoterlesslacZgene. Six of these pools were chosen, and individual pattern‐producing plasmids within these pools were identified. The expression patterns have been characterized more thoroughly than in the original screen, thereby providing molecular markers for differentiation of several cell types. Many of the expression patterns involve more than one cell type. The genomic origin of the inserts of active plasmids were determined through localization on the physical genome map. © 1993 wiley

ISSN:1058-8388    

DOI:10.1002/aja.1001960206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractSerine/threonine kinase transmembrane proteins are a new family of growth factor signal transducers that includes several isoforms of the activin type II receptor and the type II receptor for transforming growth factor‐β. In an effort to clone the receptor for Mullerian inhibiting substance, a member of the transforming growth factor‐β superfamily, oligonucleotide primers designed from conserved regions of these receptors' kinase domains were used for PCR amplification of fetal rat urogenital ridge cDNA. We isolated four novel receptors in this manner (desingnated R1–R4), each of which has structural features of the previously cloned kinases, including a small extracellular ligand‐binding domain, a single hydrophobic transmembrane domain, and an intracellular serine/threonine kinase domain. In addition, each has characteristic kinase subdomains and conserved serine/threonine kinase sequences found in this family. Northern analysis revealed mRNA expression of R1‐R4 in several tissues, including fetal urogenital ridge, testis, and ovary, as well as brain and lung. In situ hybridization further localized R1 to mesenchyme of the 14.5 to 15‐day fetal rat Mullerian duct and to oocytes of preantral and antral follicles, sites that are consistent with the predicted localization of Mullerian inhibiting substance receptor. In addition, R2 localized specifically to seminiferous tubules of the postnatal testis. These newest members of the activin and transforming growth factor‐β type II receptor family should help define the molecular mechanisms by which this ligand superfamily affects cell growth and differentiation via membrane phosphorylation. © 199

ISSN:1058-8388    

DOI:10.1002/aja.1001960207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe mouse γF‐crystallin gene, one of six differentially regulated members of the γ‐crystallin gene family, is expressed exclusively in central nuclear fiber cells of the adult lens. The expression of this gene is controlled through regulatory elements contained in two upstream enhancers and the proximal promoter. Here we show that while the upstream enhancers and the proximal promoter could each direct gene expression in fiber cells formed at early stages of lens growth and development, cooperation between these elements is required to achieve expression in fiber cells formed at later stages. Evidence is provided that cooperative interaction between these elements modulates gene expression by increasing promoter strength. We also show that sequences within the proximal promoter region that bind lens cell nuclear factor γF‐1 are sufficient to elicit gene expression in central nuclear fiber cells of the adult lens. © 1993 wiley

ISSN:1058-8388    

DOI:10.1002/aja.1001960208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:1058-8388    

DOI:10.1002/aja.1001960201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY