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R Schuh

Publications and source records attributed to R Schuh.

At least 37 records · Page 2Linked to original sources
PubMed1991

Identification of target genes of the homeotic gene Antennapedia by enhancer detection.

Localized expression of the homeotic gene Antennapedia (Antp) in Drosophila melanogaster is required for normal development of the thoracic segments. When the Antp gene is expressed ectopically in the larval primordium of the antenna, the antennal imaginal disc, the developmental fate of the disc is switched and the adult antenna is transformed to a mesothoracic leg. We screened approximately 550 different fly strains carrying single copies of an enhancer-detector transposon to identify regulatory elements and corresponding genes that are either activated or repressed in antennal discs in response to this transformation. Several regulatory elements that are either direct or indirect targets of Antp were found. One transposant that expresses the reporter gene (lacZ) in the antennal disc, but not in the leg disc, was studied in more detail. The enhancer detector in this strain is located near a similarly regulated gene at the spalt (sal) locus, which encodes a homeotic function involved in embryonic head and tail development. The expression of this newly discovered gene, spalt major (salm) is strongly repressed in gain-of-function mutants that express Antp in the antennal disc. Recessive loss-of-function mutations (Antp-) have the opposite developmental effect; they cause the differentiation of antennal structures in the second leg disc. Accordingly, salm is derepressed in clones of homozygous Antp- cells. Therefore, we conclude that Antp negatively regulates salm. The time course of the interaction and reporter gene fusion experiments suggests (but does not prove) a direct interaction between Antp and cis-regulatory elements of salm. Our analysis of several enhancer-detector strains suggests that the basic patterning information in the antennal and leg imaginal discs is very similar.

Alleles↗
PubMed1990

Effect of gamma-hydroxybutyrate on local and global glucose metabolism in the anesthetized cat brain.

This study addresses three topics in the chloralose-anesthetized cat: (a) distribution of local CMRglc: values ranging from 5 to 109 mumols/100 g/min were found in 37 brain structures and the mean CMRglc over all examined structures was 30.6 mumols/100 g/min; (b) effect of gamma-hydroxybutyrate (GHB, 250 mg/kg i.v.) on local CMRglc, which was significantly (p less than 0.05) depressed in 16 of 37 structures, most prominently in the auditory system, and the mean CMRglc over all structures after GHB was 20.4 mumols/100 g/min; and (c) global values of CMRglc, CMRO2, and CBF before and after GHB: in these experiments, a modified Kety-Schmidt technique was employed measuring saturation/desaturation of inhaled H2 and concentrations of glucose and oxygen in aortic and sagittal sinus blood. CBF and CMRO2 were not altered after GHB, whereas CMRglc was significantly decreased from 35.7 to 28.8 mumols/100 g/min. The values of CMRglc obtained with both techniques (autoradiography and the Kety-Schmidt technique) are concordant, especially when considering the different sampling areas of both methods. The main finding of the present study is a reduction in cerebral glucose consumption after GHB, irrespective of the technique of measurement. This reduction occurs at an unchanged CMRO2 and CBF.

Animals↗
PubMed1989

[Pattern formation in Drosophila].

Drosophila proved an excellent system to study molecular processes in establishing the body pattern of an embryo. Genes which are active during oogenesis provide localized cues which regulate a cascade of zygotic genes that determines the developmental fate of the blastoderm cells along the longitudinal axis of the embryo.

Animals↗
PubMed1989

The homeotic gene spalt (sal) evolved during Drosophila speciation.

The region-specific homeotic gene spalt (sal) acts in two separate domains in the head and tail region of the Drosophila melanogaster embryo. Based on comparative morphology, sal is likely to be involved in the establishment of the head during the evolution of invertebrates and thus, it should be conserved. We have analyzed the conservation of the segmentation genes Krüppel (Kr) and even-skipped (eve) in parallel with sal coding sequences in several Drosophila species that are evolutionarily separated by up to 60 million years. To our surprise, sal sequences appear to be conserved in the Sophophora subgenus of the Drosophila genus but not in the Drosophila subgenus. On the other hand, the segmentation and other homeotic genes are conserved in the Drosophila subgroup as well. Our data suggest that sal encodes an accessory function that evolved relatively late during Drosophila speciation rather than playing a fundamental evolutionary role similar to that of other homeotic genes.

Amino Acid Sequence↗
PubMed1989

Distribution of injected anti-Thy-1 monoclonal antibodies in mouse lymphatic organs: evidence for penetration of the cortical blood-thymus barrier, and for intravascular antibody-binding onto lymphocytes.

The localization of monoclonal anti-Thy-1 binding in mouse thymus, spleen, and lymph nodes was studied at early intervals after intravenous (i.v.), intraperitoneal (i.p.) and subcutaneous (s.c.) injection of a single dose of the monoclonal antibody (MAb). Five minutes after i.v. injection, anti-Thy-1 was bound to cortical thymocytes surrounding capillaries in the thymic cortex, to thymic cells beneath the thymic capsule and to medullary thymocytes around venules of the thymus medulla. When anti-Thy-1 was injected i.p. or s.c. the MAb was first deposited in capillary walls in the thymus cortex and did not appear on thymocytes outside of capillaries until 60 min after injection. These findings suggest that thymic cortical capillaries are permeable for anti-Thy-1 MAb contrary to the generally accepted principle of a blood thymus barrier to antigens in thymic cortex. Some cortex capillaries also became permeable for peroxidase when injected 15 min after anti-Thy-1 MAb. Anti-Thy-1 MAb penetration into spleen white pulp and lymph node paracortex occurs along the circulatory pathway of the vascular system in the spleen and of lymphatics in lymph nodes. But those lymphocytes with a strong anti-Thy-1 MAb loading always appeared along the pathways of lymphocyte circulation indicating that the most intense contact between anti-Thy-1 MAb and T-lymphocytes occurs not in the lymphatic organs but during the intravascular period of recirculation of lymphocytes.

Animals↗
PubMed1989

Probing Drosophila gene function by antisense RNA.

The conventional technique for assigning a particular genetic function to a cloned transcription unit has relied on the rescue of the mutant phenotype by germ line transformation. An alternative approach is to mimic a mutant phenotype by the use of antisense RNA injections to produce phenocopies. This approach has been successfully used to identify genes involved in early pattern forming processes in the Drosophila embryo. At the time when antisense RNA is injected, the embryo develops as a syncytium composed of about 5000 nuclei which share a common cytoplasm. The gene interactions required to establish the body plan occur before cellularization at the blastoderm stage. Thus the nuclei and their exported transcripts are accessible to the injected antisense RNA. The antisense RNA interferes with the endogenous RNA by an as yet unidentified mechanism. The extent of interference is only partial and produces phenocopies with characteristics of weak mutant alleles. In our lab and others, this approach has been successfully used to identify several genes required for normal Drosophila pattern formation.

Animals↗
PubMed1988

Molecular characterization of spalt, a homeotic gene required for head and tail development in the Drosophila embryo.

The isolation, identification and structure of the spalt gene is described. This novel homeotic gene of Drosophila is required for the establishment of the posterior-most head and the anterior-most tail segments of the embryo. It encodes a small mRNA of 0.8 kb which is under the control of over 15 kb of upstream sequences as indicated by the phenotype of transformed embryos. The putative spalt protein contains internal repeats and other interesting structural motifs but no homeo box. The spalt transcript accumulates motifs but no homeo box. The spalt transcript accumulates to high levels in the segmental anlagen affected in mutant embryos but is also found in regions of the embryo where no functional requirement has been demonstrated.

Journal Article↗
PubMed1988

Chromosomal mapping of the structural gene coding for the mouse cell adhesion molecule uvomorulin.

The gene coding for the mouse cell adhesion molecule uvomorulin has been mapped to chromosome 8. Uvomorulin cDNA clone F5H3 identified restriction fragment length polymorphisms in Southern blots of genomic DNA from mouse species Mus musculus domesticus and Mus spretus. By analyzing the segregation pattern of the gene in 75 offspring from an interspecific backcross a single genetic locus, Um, was defined on chromosome 8. Recombination frequency between Um and the co-segregating loci serum esterase 1 (Es-1) and tyrosine aminotransferase (Tat) places Um about 14 centimorgan (cM) distal to Es-1, and 5 cM proximal to Tat. In situ hybridization of uvomorulin [3H]cDNA to mouse metaphase chromosomes located the Um locus close to the distal end of chromosome 8 (bands C3-E1). Since uvomorulin is evolutionarily highly conserved, its chromosomal assignment adds an important marker to the mouse genetic map.

Animals↗
PubMed1987

The structure of cell adhesion molecule uvomorulin. Insights into the molecular mechanism of Ca2+-dependent cell adhesion.

We have determined the amino acid sequence of the Ca2+-dependent cell adhesion molecule uvomorulin as it appears on the cell surface. The extracellular part of the molecule exhibits three internally repeated domains of 112 residues which are most likely generated by gene duplication. Each of the repeated domains contains two highly conserved units which could represent putative Ca2+-binding sites. Secondary structure predictions suggest that the putative Ca2+-binding units are located in external loops at the surface of the protein. The protein sequence exhibits a single membrane-spanning region and a cytoplasmic domain. Sequence comparison reveals extensive homology to the chicken L-CAM. Both uvomorulin and L-CAM are identical in 65% of their entire amino acid sequence suggesting a common origin for both CAMs.

Amino Acid Sequence↗
PubMed1987

Analysis of Krüppel protein distribution during early Drosophila development reveals posttranscriptional regulation.

We have examined the spatial and temporal patterns of expression of the Krüppel (Kr) protein, a gap gene product, during Drosophila embryogenesis. Antibodies directed against the Kr protein revealed patterns of nuclear staining that represent subpatterns of Kr transcript accumulation in particular tissues. This indicates that the distribution of Kr protein is not a direct response to Kr mRNA accumulation, and that Kr protein expression requires a second level of control in addition to spatially regulated transcription. Our data provide evidence for posttranscriptional control that may involve an intron present in the 5' region of one of the two Kr transcripts. The intron-containing transcript is the only potential source of new Kr protein synthesis after gastrulation. The finding of late and transient patterns of Kr activity in several tissues, such as the developing nervous system, amnion serosa, and muscle precursor cells suggests that Kr activity may be required in several developmental processes after segmentation has been completed.

Animals↗
PubMed1987

In vivo immunosuppression by pan-T cell antibodies relates to their isotype and to their C1q uptake.

There is considerable interest in the use of monoclonal anti-T cell antibodies for immunosuppression during organ transplantation. However, the in vitro cytotoxic titers of these monoclonal reagents do not correlate with their immunosuppressive potency when injected in vivo. A relationship nevertheless seems to exist between immunosuppression and the isotype of anti-mouse Thy-1 antibodies, because among several anti-Thy-1 antibodies of mouse and rat origin, the only two found to cause immunosuppression in vivo belonged to the rat IgG2b and mouse IgG2a isotype. We show here that a quantitative positive correlation exists between an antibody-induced humoral effector mechanism and immunosuppression. We measured the uptake of the C1q complement subunit by polyclonal rabbit and rat anti-thymocyte globulin and also seven monoclonal anti-Thy-1 antibodies in an immunohistochemical assay or a radioimmunoassay. Immunosuppression was studied in a murine graft-vs-host and skin allograft model. Our results suggest strongly that a stable association between the C1 protein and a potential binding antibody is an essential prerequisite of antibody-dependent cell inhibition in vivo that suppresses the immunoresponse against strongly incompatible transplantation antigens.

Animals↗
PubMed1987

The gooseberry-zipper region of Drosophila: five genes encode different spatially restricted transcripts in the embryo.

Genetic analysis of the Drosophila chromosome region 60 E9-F1 identified two functions affecting embryonic development; gooseberry (gsb), a segment polarity gene, and zipper (zip), an unclassified gene which affects cuticle formation severely. By contrast, molecular analysis revealed five genes with different temporal and spatial patterns of expression in the embryo. Candidate genes for gsb and zip functions were identified. Two adjacent genes are eventually expressed in regular stripes within the posterior region of each segment. One of them is expressed initially in a pair-rule mode; the second gene expresses reduced levels of transcripts in a mutant which leaves the transcribed region and the sequences up to the second gene intact. This observation, the patterns of transcripts in the embryo and the genetic data suggest that both genes are involved in gooseberry segmentation function. zip is expressed in neural tissue and not in epidermal anlagen. Embryos lacking zip activity also develop abnormal neural tissue consistent with the argument that the zip cuticle phenotype is a secondary effect. Additional newly identified genes are expressed in specific domains of the embryo, covering mesoderm anlagen and the dorsal region of embryos at blastoderm stage, respectively.

Journal Article↗
PubMed1987

[Transdermal scopolamine or droperidol in the prevention of postoperative nausea and vomiting in cholecystectomy patients].

Scopolamine, applicable without severe side effects as a transdermal therapeutic system (TTS), has a pronounced postoperative antiemetic effect. In one publication there was found even a 50% reduction of emetic symptoms compared with placebo. In this study TTS-Scopolamine was compared with a single dose of 7.5 mg Droperidol in a group of 40 Patients undergoing cholecystectomy under standardised balanced anesthesia. After cholecystectomy patients are very much inclined for postoperative nausea and vomiting since it is an abdominal operation and it is more often necessary in women than in men. In this randomized, one-side-blind study the antinausea and antiemetic effect of transdermal Scopolamine was insufficient and significantly less than with Droperidol. In the Droperidol-group there were 45% of patients without emetic symptoms, in the Scopolamine-group only 15%. Vomiting occurred in 25% of patients in the Droperidol-group and in 50% of patients in the Scopolamine-group. Unfavourable CNS-side-effects could not be found either with transdermal scopolamine or with Droperidol. As favourable side-effects there was found a more even postoperative blood-pressure-curve in the Droperidol-group and a better scoring of preoperative sleep in the Scopolamine-group. Overall there is need for an exact indication for transdermal Scopolamine as a postoperative antiemetic. In this study Droperidol turned out to be a much stronger antiemetic for patients undergoing cholecystectomy.

Administration, Cutaneous↗
PubMed1986

A conserved family of nuclear proteins containing structural elements of the finger protein encoded by Krüppel, a Drosophila segmentation gene.

Krüppel (Kr), a segmentation gene of Drosophila, encodes a protein sharing structural features of the DNA-binding "finger motif" of TFIIIA, a Xenopus transcription factor. Low-stringency hybridization of the Kr finger coding sequence revealed multiple copies of homologous DNA sequences in the genomes of Drosophila and other eukaryotes. Molecular analysis of one Kr-homologous DNA clone identified a developmentally regulated gene. Its product, a finger protein, relates to Kr by the invariant positioning of crucial amino acid residues within the finger repeats and by a stretch of seven amino acids connecting the finger loops, the "H/C link." This H/C link is conserved in several nuclear and chromosome-associated proteins of Drosophila and other eukaryotic organisms including mammals. Our results demonstrate a new subfamily of evolutionarily conserved nuclear and possibly DNA-binding proteins that again relate to a Drosophila segmentation gene as in the case of the homeo domain.

Animals↗