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U Rasmussen

Publications and source records attributed to U Rasmussen.

13 recordsLinked to original sources
PubMed2002

Characterization of Trichodesmium spp. by genetic techniques.

The genetic diversity of Trichodesmium spp. from natural populations (off Bermuda in the Sargasso Sea and off North Australia in the Arafura and Coral Seas) and of culture isolates from two regions (Sargasso Sea and Indian Ocean) was investigated. Three independent techniques were used, including a DNA fingerprinting method based on a highly iterated palindrome (HIP1), denaturing gradient gel electrophoresis of a hetR fragment, and sequencing of the internal transcribed spacer (ITS) of the 16S-23S rDNA region. Low genetic diversity was observed in natural populations of Trichodesmium spp. from the two hemispheres. Culture isolates of Trichodesmium thiebautii, Trichodesmium hildebrandtii, Trichodesmium tenue, and Katagnymene spiralis displayed remarkable similarity when these techniques were used, suggesting that K. spiralis is very closely related to the genus TRICHODESMIUM: The largest genetic variation was found between Trichodesmium erythraeum and all other species of Trichodesmium, including a species of KATAGNYMENE: Our data obtained with all three techniques suggest that there are two major clades of Trichodesmium spp. The HIP1 fingerprinting and ITS sequence analyses allowed the closely related species to be distinguished. This is the first report of the presence of HIP1 in marine cyanobacteria.

Bacterial Proteins↗
PubMed2001

Characterization by genotypic methods of symbiotic Nostoc strains isolated from five species of Gunnera.

The genetic diversity of ten symbiotic Nostoc strains isolated from different Gunnera species was investigated. The strains were analyzed using molecular methods with different taxonomic resolutions, including restriction fragment length polymorphisms (RFLP) of the PCR-amplified 16S ribosomal gene and the 16S-23S internal transcribed spacer (ITS) region combined with computer-assisted analyses. The functional gene hetR, assigned to heterocyst differentiation, was used for denaturing gradient gel electrophoresis. A high genetic diversity was observed among the isolates even in the conserved gene coding for the small ribosomal unit. No correlation was observed between clustering of cyanobacteria and the host species of Gunnera.

Bacterial Proteins↗
PubMed2000

Cyanobacterial diversity in geographically related and distant host plants of the genus Gunnera.

The diversity among 45 cyanobacterial isolates from 11 different Gunnera species originating from different geographical areas was examined. By means of polymerase chain reaction (PCR) fingerprinting with short tandemly repeated repetitive (STRR) sequences as primers, ten groups of symbiotic cyanobacteria and five unique isolates not belonging to a particular group were identified. Most groups were restricted to one geographical area, indicating a limited distribution of related cyanobacterial strains. An extensive cyanobacterial diversity was found both within and between the 11 different Gunnera species. Within a particular plant and even within the same stem gland, more than one cyanobacterial strain at a time could be present. These results indicate a low specificity in Gunnera-Nostoc symbiosis.

Cyanobacteria↗
PubMed1998

Fingerprinting of cyanobacteria based on PCR with primers derived from short and long tandemly repeated repetitive sequences.

The presence of repeated DNA (short tandemly repeated repetitive [STRR] and long tandemly repeated repetitive [LTRR]) sequences in the genome of cyanobacteria was used to generate a fingerprint method for symbiotic and free-living isolates. Primers corresponding to the STRR and LTRR sequences were used in the PCR, resulting in a method which generate specific fingerprints for individual isolates. The method was useful both with purified DNA and with intact cyanobacterial filaments or cells as templates for the PCR. Twenty-three Nostoc isolates from a total of 35 were symbiotic isolates from the angiosperm Gunnera species, including isolates from the same Gunnera species as well as from different species. The results show a genetic similarity among isolates from different Gunnera species as well as a genetic heterogeneity among isolates from the same Gunnera species. Isolates which have been postulated to be closely related or identical revealed similar results by the PCR method, indicating that the technique is useful for clustering of even closely related strains. The method was applied to nonheterocystus cyanobacteria from which a fingerprint pattern was obtained.

Journal Article↗
PubMed1994

Interaction of von Willebrand factor with platelets activated by thrombin or a synthetic 7-amino acid peptide derived from the cleaved thrombin receptor.

Thrombin and the 7-mer agonist peptide from its receptor (SFLLRNP) were compared for their ability to promote the binding of vWF to platelets. Identical Ca(2+)-dependence and kinetics of activation were observed. Studies of inhibition of the binding by a series of monoclonal antibodies to GPIb, GPIIb/IIIa and vWF and experiments performed using platelets from patients with Glanzmann thrombasthenia or Bernard-Soulier syndrome enabled to identify GPIIb/IIIa as the receptor of vWF. Binding isotherms of vWF in the presence of an excess of either agonist yielded a similar number of binding sites but an apparent dissociation constant slightly but consistently higher with the 7-mer peptide than with thrombin. The latter point was confirmed by studying the binding of limiting amounts of vWF to platelets as a function of the agonist concentration. The lower affinity in the presence of 7-mer peptide was not corrected by adding increasing amounts of FPR-thrombin, a derivative with irreversibly blocked active site but retaining the binding properties of the active enzyme. Conversely, the higher affinity observed with thrombin was decreased when platelets were treated with Serratia protease which selectively cleaved GPIb but did not affect the function of the thrombin receptor and GPIIb/IIa. Our data thus suggest that both the 7-mer peptide and thrombin are able to induce the assembly of functional GPIIb/IIIa.(ABSTRACT TRUNCATED AT 250 WORDS)

Bernard-Soulier Syndrome↗
PubMed1993

Plant chitinases.

Explore the source record for details and available documents.

Chitinases↗
PubMed1992

Cloning and characterization of a pathogen-induced chitinase in Brassica napus.

A chitinase cDNA clone from rapeseed (Brassica napus L. ssp. oleifera) was isolated. The cDNA clone, ChB4, represents a previously purified and characterized basic chitinase isozyme. The longest open reading frame in ChB4 encodes a polypeptide of 268 amino acids. This polypeptide consists of a 24 amino acid N-terminal signal peptide, a cysteine-rich domain and a catalytic domain. The primary structure of the mature ChB4 shows a low degree of identity with class I and II chitinases, 43-48% and 35%, respectively. In contrast, ChB4 shows 62% identity to a basic sugar-beet chitinase and 63% identity to an acidic chitinase from bean. The expression of chitinase messenger RNA (mRNA) in response to infection with Phoma lingam (Tode ex. Fr.) Desm. was examined by northern hybridization and scintilation counting. A differential induction was seen between resistant and susceptible cultivars where 3-fold higher chitinase transcript levels were estimated one day after inoculation in resistant as compared to susceptible cultivar. This difference diminished eight days after inoculation. Southern hybridization analysis indicates that the chitinase is encoded by a small family of genes.

Amino Acid Sequence↗
PubMed1981

Metabolic response to subtotal thyroidectomy in propranolol-treated thyrotoxic patients.

Changes in plasma cortisol, glucose, cyclic AMP, blood leucocytes, pulse rate and body temperature were measured during and for 24 h after subtotal thyroidectomy in eight propranolol-treated (120-160 mg per day) mild to moderate thyrotoxic patients and eight patients with a non-toxic goitre. The results showed a similar metabolic response to surgery in the two groups without any trends towards a hypermetabolic response in the toxic group. The accumulating evidence of the safety of preoperative preparation with propranolol in patients with mild to moderate thyrotoxicosis is thus supported by our results.

Adult↗
PubMed1979

On the mechanism of histamine release induced by thapsigargin from Thapsia garganica L.

Thapsigargin (Tg) is a pure chemical compound isolated from Thapsia garganica with a molecular weight of 650. It releases histamine from isolated rat mast cells but not from isolated histamine-retaining mast cell granules. The rate of release is markedly influenced by pretreatment of mast cells with Tg prior to the addition of calcium. In agreement with the effect of the ionophore A23187 but in contrast to many other calcium-dependent histamine-releasing agents, cells preincubated with Tg respond to the secretory action of calcium whenever the ion is introduced. However, after dilution of Tg-pretreated cells histamine release induced by the addition of calcium became dependent on the time of its addition. The secretory reaction induced by Tg and calcium can be divided into a two-step reaction at 37 degrees C. Pretreatment of mass cells with Tg renders the cells insensitive to the secretory action of compound 48/80 in the absence of calcium, and this effect could be partly counteracted if 1 mM of strontium was added together with compound 48/80. It is concluded that among various calcium- and energy-dependent histamine-releasing agents Tg most closely resembles the action of fluoride on isolated rat mast cells.

Animals↗
PubMedDate not supplied

[The first protein map of Synechococcus sp. strain PCC 7942].

The first protein map was developed of Synechococcus sp. strain PCC 7942, a model organism for studies of photosynthesis, prokaryotic circadian rhythms, cell division, carbon-concentrating mechanisms, and adaptive responses to a variety of stresses. The proteome was analyzed by two-dimensional gel electrophoresis with subsequent MALDI-TOF mass spectroscopy and database analysis. Of the 140 analyzed protein spots, 110 were successfully identified as 62 different proteins, many of which occurred as multiple spots on the gel. The identified proteins participate in the major metabolic and cellular processes in cyanobacterial cells during the exponential growth phase. In addition, 14 proteins which were previously either unknown or considered to be hypothetical were shown to be true gene products in Synechococcus sp. strain PCC 7942. These results may be helpful for the annotation of the recently sequenced genome of this cyanobacterium, as well as for biochemical and physiological studies of Synechococcus.

Bacterial Proteins↗