Showing papers by "University of Basel published in 1985"

Studies of the Virgo Cluster. II - A catalog of 2096 galaxies in the Virgo Cluster area. V - Luminosity functions of Virgo Cluster galaxies

Abstract: The present catalog of 2096 galaxies within an area of about 140 sq deg approximately centered on the Virgo cluster should be an essentially complete listing of all certain and possible cluster members, independent of morphological type. Cluster membership is essentially decided by galaxy morphology; for giants and the rare class of high surface brightness dwarfs, membership rests on velocity data. While 1277 of the catalog entries are considered members of the Virgo cluster, 574 are possible members and 245 appear to be background Zwicky galaxies. Major-to-minor axis ratios are given for all galaxies brighter than B(T) = 18, as well as for many fainter ones.

Isolation of a homoeo box-containing gene from the engrailed region of Drosophila and the spatial distribution of its transcripts.

Abstract: The engrailed locus of Drosophila melanogaster has the characteristics of both a homoeotic gene and a segmentation gene; like a homoeotic gene, it specifies the development of specific compartments of the Drosophila embryo (the posterior compartments of each segment), and, like mutations of segmentation genes, lethal alleles of engrailed affect also the pattern of segmentation of the embryo. Here we report that like many of the homoeotic genes of the bithorax and Antennapedia complexes, engrailed has a ‘homoeo box’ sequence; also, like the segmentation gene fushi tarazu , the engrailed gene displays a periodic pattern of expression in Drosophila embryos.

Isolation of caudal, a Drosophila homeo box-containing gene with maternal expression, whose transcripts form a concentration gradient at the pre-blastoderm stage.

Abstract: We report the isolation and characterization of caudal (cad), a previously unknown Drosophila homeo box-containing gene from the 38E region on the left arm of the second chromosome. This homeo box has diverged from the prototype sequence in Antennapedia, but contains subregions which are highly homologous. By Northern analysis and in situ hybridization experiments two transcripts of 2.4 kb were found to accumulate in nurse cells and in the oocyte during oogenesis. These transcripts generate a transient concentration gradient along the antero-posterior axis at the syncytial blastoderm stage. At the cellular blastoderm stage transcripts accumulate in a single band from 13-19% egg length at the posterior end. One zygotic transcript of 2.6 kb is detected. At later stages this transcript is localized in ectodermally and endodermally derived tissues such as the proctodeum, the Malpighian tubules and the posterior midgut. The 2.6-kb transcript is detectable until the onset of metamorphosis.

Alzheimer changes in nondemented patients younger than sixty-five: Possible early stages of Alzheimer's disease and senile dementia of Alzheimer type

Abstract: Senile plaques (SP) and neurofibrillary tangles (NFT) were found in 38 (74.5%) of 51 unselected brains of nondemented patients who died between the ages of 55 and 64 years. A high proportion (22, or 43%) had only NFTs. These were consistently present in the entorhinal cortex and/or the hippocampus; the olfactory bulb, the amygdala, and the nucleus basalis of Meynert were also occasionally involved. Isolated SPs were seen in only 3 brains (6%); SPs and NFTs coexisted in 13 (25.5%). The distribution patterns of NFTs and SPs differed. NFTs were seen in discrete, mostly single neurons of the structure, already noted, whereas SPs occurred in a more generalized distribution over the base and convexity of the cerebrum. The plaques were usually small (30 mu in diameter) and consisted of delicate fibrillary material. Other types of SP were also seen. The incidence of various types of plaques in nondemented patients is considered to indicate a morphological evolution of these structures.

Low temperature embedding with Lowicryl resins: two new formulations and some applications

Abstract: Lowicryl K4M and HM20 are methacrylate/acrylate based low temperature embedding resins for biological material which can be used in conjunction with either the progressive lowering of temperature (PLT) technique or with freeze-substitution. K4M and HM20 are applicable over a very extended temperature range, approximately 220 K to 340 K. With two new resins, K11M and HM23, one can reach even lower temperatures, c. 200 K. Freeze-substitution combined with low temperature embedding allows for very mild or no chemical fixation which seems to increase the sensitivity of immunocytochemical localization of antigens on sections.

An enhancer-like sequence within the Xenopus U2 gene promoter facilitates the formation of stable transcription complexes.

Abstract: Enhancers are eukaryotic promoter elements that increase transcriptional efficiency in a manner relatively independent of their position and orientation with respect to a nearby gene. There is growing evidence that enhancer action is mediated by transacting factors, but the mode of action of these factors is not yet known. We report here on the Xenopus U2 gene promoter, which contains two sequence elements. The distal sequence element increases promoter activity 20-fold by facilitating the formation of stable transcription complexes. A synthetic 14-base-pair (bp) oligonucleotide corresponding to part of the distal sequence element, which shows homology to an immunoglobulin gene promoter element and to both the simian virus 40 (SV40) and the immunoglobulin heavy-chain gene enhancers, stimulates transcription in an orientation-independent manner.

Porin channel triplets merge into single outlets in Escherichia coli outer membranes.

Abstract: Previous observations on the structural1–4 and functional5 properties of porin, the matrix protein of Escherichia coli, have indicated that the channel-forming trimers span the outer membranes of the bacterial cell, forming a molecular sieve6. By using electron microscopy and image reconstruction, we demonstrate here that three channels on the outer surface of the cell merge into a single channel at the periplasmic face. Conductance measurements using conditions under which single activated triplets could be observed led us to conclude that the three individual consecutive closing steps reflect three channels within a single trimeric unit. Statistical analysis of conductance levels revealed that the first relaxation step is distinctly smaller than the two subsequent channel closings. This functional observation can be explained if the channels of porin trimers coalesce.

Bowenoid Papulosis: Presence of Human Papillomavirus (HPV) Structural Antigens and of HPV 16-Related DNA Sequences

Abstract: † This study reviews 39 cases of anogenital bowenoid papulosis lesions in 22 individuals of both sexes that were analyzed clinically, histologically, immunocytochemically, and virologically. Macroscopically, three different types of lesions were demonstrated: erythematous macules; papules (lichenoid and/or pigmented papules); and leukoplakialike lesions. Microscopically, bowenoid papulosis fulfills the criteria of a squamous cell carcinoma in situ. Much like oral precancers, three distinct growth patterns (flat, endophytic, and exophytic) could be differentiated, which did not correlate with the clinical aspect of the lesions. In only two (5.12%) of the 39 cases of bowenoid papulosis could structural antigens of papillomaviruses be detected immunocytochemically (peroxidase-antiperoxidase technique). The DNA from 12 lesions that were analyzed for the presence of papillomavirusspecific sequences hybridized stringently in all cases with the human papillomavirus 16 specific DNA probe labeled with phosphorus 32. ( Arch Dermatol 1985;121:858-863)

Diacylglycerol in large α-actinin/actin complexes and in the cytoskeleton of activated platelets

Abstract: The interaction of the cytoskeleton with plasma membranes may be mediated by vinculin, alpha-actinin and other proteins; alpha-actinin can interact specifically with model membranes only if they contain diacylglycerol and palmitic acid. On stimulation of platelets by thrombin, which leads to a reorganization of the cytoskeleton, diacylglycerol is produced rapidly, simultaneously with the disappearance of phosphatidylinositol. One important function of the diacylglycerol produced in platelets may be the activation of the Ca2+-and phospholipid-dependent protein kinase C. We show here that, in the presence of diacylglycerol and palmitic acid, a supramolecular complex between alpha-actinin and actin is formed in vitro. In the electron microscope, this complex displays substructures similar to those of microfilament bundles in vivo. Furthermore, such alpha-actinin/lipid complexes can also be formed in situ during the stimulation of blood platelet aggregation. Thus, alpha-actinin may be one of the proteins directly involved in structures connecting the cytoskeleton to cell membranes.

Geochemistry, geochronology and petrology of Monte Mucrone: An example of EO-alpine eclogitization of Permian granitoids in the Sesia-Lanzo Zone, Western Alps, Italy

Abstract: A Permian granitoid intrusion, exposed on Monte Mucrone, Sesia-Lanzo Zone, Italy, was metamorphosed under high-pressure conditions. To elucidate the metamorphic history of this granitoid complex, investigations have been made into the chemistry of the protolith, possible mass transfer during metamorphism, phase chemistry and implications for P-T conditions, and the age of metamorphic events. The metagranitoids contain Na-pyroxene, quartz, white mica, garnet and zoisite, and vary from rocks showing a well-preserved granitic texture to strongly deformed schists and gneisses. The rocks are of granitic to granodioritic composition and originated as an I-type granite pluton. With the exception of addition of H2O, the rock series behaved isochemicaliy throughout high-pressure metamorphism and later tectonic and retrograde transformations. P,T estimates based on Na-pyroxenes, garnet-clinopyroxene and garnet-biotite pairs give minimum pressures of ∼ 14 kbar at 600°C for the peak of the eclogite metamorphism. Age determinations by RbSr and KAr methods give 129-Ma for the rejuvenation of the total rock and 114-Ma isochrons for garnet and clinopyroxene, the first eclogite phase minerals. White-mica cooling ages scatter from 90 to 60 Ma.

Structure and macromolecular organization of type VI collagen.

Abstract: Collagen VI is a large, disulfide-bonded protein complex which is widely distributed in connective tissue The constituent polypeptide chains (Mr = 110,000-140,000) consist of collagenous and noncollagenous segments, are degraded to chains of about half the size when collagen VI is solubilized by pepsin, and assemble to a unique pattern of oligomers As revealed by electron microscopy, the triple-stranded protomer consists of a triple helix 105 nm in length flanked on each side by globular domains of similar size (diameter about 7 nm) Protomers are assembled to dimers by an antiparallel staggered alignment of triple-helical segments This leads to inner regions, 75 nm in length, of two slightly supercoiled triple helices flanked by globular domains At both sides 30-nm-long outer triple-helical segments emerge that are terminated by globules Tetramers are formed from laterally aligned dimers that cross with their outer triple-helical segments in a scissors-like fashion The same structures, except with much smaller globular domains, are found in pepsin-treated collagen VI Disulfide-linked collagen VI produced by cultured fibroblasts has a size similar to that of genuine collagen VI found in tissue extracts Larger forms of collagen VI are assembled from tetramers by end-to-end aggregation which because of an overlap of the outer segments brings all globular domains close together This arrangement predicts microfibrillar structures in tissues with a periodicity of 100-110 nm and a diameter of 5-10 nm Structures consistent with this proposal were indeed found by immunoelectron microscopy of placenta and aorta using the ferritin technique Large, lateral aggregates of collagen VI microfibrils may in addition exist in cell cultures and tissues ("zebra collagen," "Luse bodies") and are presumably maintained by contacts between globular domains

Nucleotide sequence analysis of the nuclear gene coding for manganese superoxide dismutase of yeast mitochondria, a gene previously assumed to code for the Rieske iron-sulphur protein.

Abstract: We have previously reported the isolation of the gene coding for a 25-kDa polypeptide present in a purified yeast QH2:cytochrome c oxidoreductase preparation, which was thus identified as the gene for the Rieske ironsulphur protein [Van Loon et al. (1983) Gene 26, 261–272]. Subsequent DNA sequence analysis reported here reveals, however, that the encoded protein is in fact manganese superoxide dismutase, a mitochondrial matrix protein. Comparison with the known amino acid sequence of the mature protein indicates that it is synthesized with an N-terminal extension of 27 amino acids. In common with the N-terminal extensions of other imported mitochondrial proteins, the presequence has several basic residues but lacks negatively charged residues. The function of these positive charges and other possible topogenic sequences are discussed. Sequences 5′ of the gene contain two elements that may be homologous to the suggested regulatory sites, UAS 1 and UAS 2 in the yeast CYC1-gene [Guarente et al. (1984) Cell 36, 503–511]. The predicted secondary structures in manganese superoxide dismutase appear to be very similar to those reported for iron superoxide dismutase, suggesting similar three-dimensional structures. Making use of the known three-dimensional structure of the Fe enzyme, the Mn ligands are predicted.

Magnetic form factor of the deuteron.

Abstract: We have measured the deuteron magnetic form factor B(q/sup 2/) for values of the momentum transfer squared between 7 and 28 fm/sup -2/. The data are compared to relativistic and nonrelativistic predictions including meson-exchange--current contributions. Significant disagreement is found for large momentum transfers.

"Thiocyanate gold": small (2-3 nm) colloidal gold for affinity cytochemical labeling in electron microscopy.

Abstract: Reduction of HAuCl4 by NaSCN or KSCN produces colloidal gold particles of 2.6 nm in diameter and homogeneous in size (coefficient of variation approximately 15%). The AuSCN sol forms protein-gold complexes. The amount of protein required to form an AuSCN-protein complex is best determined in the electron microscope, where serial dilutions of protein with gold sol are inspected for the presence of aggregates. By immuno-electron microscopy SCN-gold complexed to protein A is active and visible as is shown by revealing alpha-amylase in rat pancreatic acinar cells.

Actin gene mutations in Drosophila; heat shock activation in the indirect flight muscles.

Abstract: We have identified four mutations affecting the actin III isoform in the indirect flight muscles (IFM) of Drosophila. One mutation does not produce any protein product, and three direct the synthesis of electrophoretic variants of actin. Complementation tests and recombination mapping indicate that all mutations are alleles of an actin gene at chromosomal band 88F (act88F gene). The effect of these mutations is restricted to the IFM. We conclude that the act88F gene is expressed only in the IFM to encode actin III, which is its major isoform. In two of the actin mutants, heat shock proteins are constitutively expressed in the IFM. Genetic evidence strongly suggest that this anomaly is primarily caused by the mutations in the act88F structural gene.

Immunohistochemical characterization of an anti-epithelial monoclonal antibody (mAB lu-5)

Abstract: A mouse monoclonal antibody (mAB lu-5) was prepared using a lung cancer cell line as an antigen. The selected clone produces an IgG with a gamma-1 heavy chain and a kappa-light-chain. Immunohistochemical testing of mAB lu-5 on 117 normal tissue biopsies and 474 tumours revealed reactivity with an intracytoplasmic, formaldehyderesistant antigen present in most epithelial and mesothelial cells, but absent in mesenchymal cells. The antibody can therefore be used as a first order, pan-epithelial marker. It proved also useful for fast tumour diagnosis on frozen sections.

Course correction circuitry translates feature detection into behavioural action in locusts

Abstract: Like other flying animals, locusts must maintain course stability despite turbulence and motor errors. Accordingly, they must detect course deviations and then correct them. The compound eyes, the ocelli and the cephalic wind hairs all detect different sensory consequences of flight instability1–3,and descending interneurones bring this information to the thorax4–9. One such interneurone of this population (the tritocerebral commissure giant neurone) is known to elicit correctional steering10.Here we characterize three additional pairs of descending deviation detector neurones and show how their information is translated into altered drive to the flight motoneurones. The central pattern generator for flight11–13,modulated by proprioceptive feedback14, gates the signal of the detector neurones in thoracic premotor interneurones9,ensuring that the flight motoneurones are affected only during flight. Further, the gating process transforms the phase-independent information of the deviation detectors into a phase-dependent signal modulated at wing-beat frequency, and transfers it to those flight motoneurones active at the time and appropriate to the corrective action required.

An estimation of the equivalent solution dielectric constant in the active-site cavity of metalloenzymes. Dependence of carboxylate-metal-ion complex stabilities on the polarity of mixed aqueous/organic solvents.

Abstract: The stability constants of the 1:1 complexes between Cu2+ and Zn2+ with formate, acetate and several phenylalkanecarboxylates, i.e. C6H5-(CH2)n-COO− with n= 0 to 5, are summarized for water, 50% aqueous ethanol and 50% aqueous dioxane (I= 0.1 M; 25°C): Complex stability depends upon carboxylate group basicity. The influence of varying amounts of ethanol or dioxane (up to 90%) on the stability of the Cu2+ and Zn2+ (M2+) complexes with formate and acetate (CA) was measured by potentiometric pH titrations. The values for pKH(CA)H and log KM(CA)M increase, as expected, with increasing amounts of the organic solvents, i.e. with decreasing solvent polarity. The changes in the equilibrium constants are also evaluated with regard to the mole fractions of the organic solvents and the corresponding dielectric constants. These results may be used to estimate for low dielectric cavities in proteins the equivalent solution dielectric constant on the basis of enhanced carboxylate basicity or metal ion binding capability (method 1). Furthermore, the measured stability constants are used for comparisons of the coordination tendency of carboxylate ligands towards zinc(II)-metalloenzymes (method 2); in this way the equivalent solution dielectric constants in the active-site cavities of bovine carbonic anhydrase and carboxypeptidase A are estimated: the values are of the order of 35 and 70, respectively. This method seems to be generally applicable to metalloproteins.

Structure of the ammonia synthesis catalyst

Abstract: The synthesis of ammonia from hydrogen and nitrogen over a reduced iron oxide catalyst is so well known1–5 and so widely used (current world capacity is close to 100 × 106 tons per year) that it may seem surprising that the mode of operation of the catalytic remains enigmatic. That both H2 and N2 must first dissociate at the catalyst surface is beyond dispute, but there is debate as to the role of various promoters (Al, K, Ca) which greatly improve the catalytic performance when added to the precursor Fe3O4. Although it is widely accepted that regions of paracrystallinity exist within the catalyst, no one has questioned its overall crystal-linity. In this work, which entails in situ X-ray diffractometry, we provide evidence that the active catalyst contains substantial amounts of a non-crystalline phase. Without promoter, reduction of Fe3O4 in the same conditions yields only crystalline α-iron.

Tritium electromagnetic form factors.

Abstract: We have measured the charge and magnetic form factors of tritium for values of the momentum transfer up to 31.3 ${\mathrm{fm}}^{\ensuremath{-}2}$. The data are compared with calculations for the three-body system including meson-exchange-current contributions.