Transformation of the plant pathogenic fungus, Rhynchosporium secalis.

The barley leaf scald fungus, Rhynchosporium secalis, was transformed to hygromycin-B and phleomycin resistance using the hph gene from E. coli and the ble gene from Streptoalloteichus hindustanus under the control of Aspergillus nidulans promoter and terminator sequences. Plasmid DNA was introduced into fungal protoplasts by PEG/CaCl2 treatment. Transformation frequencies varied from 59 to 493 transformants per 10 microg of DNA and 5 x 10(7) protoplasts. The antibiotic-resistant phenotype appeared to be stable under selective, as well as under non-selective, conditions for several generations. Co-transformation using the E. coli uidA gene under the control of A. nidulans promoter and terminator sequences on a non-selectable plasmid occurred at frequencies of up to 66%.

The race-specific elicitor, NIP1, from the barley pathogen, Rhynchosporium secalis, determines avirulence on host plants of the Rrs1 resistance genotype.

NIP1, a small phytotoxic protein secreted by the barley pathogen Rhynchosporium secalis, is a race-specific elicitor of defense responses in barley cultivars carrying the resistance gene, Rrs1. Co-inoculation employing spores from a virulent fungal race together with the NIP1 protein converted the phenotype of the interaction from compatible to incompatible only on Rrs1-containing plants. In addition, transformation of a virulent fungal race with the nip1 gene yielded avirulent transformants. This demonstrated that the protein is the product of a fungal avirulence gene. The fungal genome was found to contain a single copy of the nip1 gene. Sequence analysis of nip1 cDNA and genomic clones revealed that the gene consists of two exons and one intron. The derived amino acid sequence comprised a secretory signal peptide of 22 amino acids and a cysteine-rich mature protein of 60 amino acids. All fungal races that were avirulent on barley cultivars of the Rrs1 resistance genotype carry and express the nip1 gene and secrete an elicitor-active NIP1 polypeptide. In contrast, races lacking this gene were virulent. In addition, single nucleotide exchanges were detected in the coding region of the nip1 alleles in one virulent fungal race and in a race whose interaction with barley is not controlled by the Rrs1 gene. The resulting exchanges of single amino acids render the gene products elicitor-inactive. Thus, the R.secalis-barley interaction provides the first example of a pathosystem conforming to the gene-for-gene hypothesis in which a plant with a particular resistance gene recognizes a pathogen by a virulence factor, i.e. one of its offensive weapons. On the fungal side, in turn, recognition by the host plant is eluded by either deletion of the encoding gene or alteration of the primary structure of the gene product.

Both open reading frames of the linear plasmid pMC3-2 from the ascomycete Morchella conica are transcribed in vivo.

Mitochondrial RNA was isolated from the morel strain Morchella conica 3 harbouring the linear plasmid pMC3-2 and subjected to gel electrophoresis followed by a Northern analysis using cloned fragments of the plasmid pMC3-2 as probes. Hybridization was obtained only with central parts of pMC3-2 and specific bands of mtRNA. The hybridization bands (2.8 kb and 1.0 kb) correspond in size to the length of the two ORFs of pMC3-2 which were deduced from nucleotide-sequence data. Thus, both ORFs, one encoding a DNA polymerase and the other a yet unknown protein, are transcribed in the mitochondria of the plasmid-bearing Morchella conica strain.

Phylogenetic relationships of linear, protein-primed replicating genomes.

Relative phylogenetic distances were estimated for those linear plasmids for which sequencing data were available by comparing the amino-acid sequences of the putative DNA- and RNA-polymerases, and phylogenetic trees were calculated. The relationships obtained accord well with those indicated by other structural characteristics of these genetic elements. It is obvious that linear plasmids constitute a separate group of genetic traits when compared with those of the adenoviruses. However, an overall relationship to these viruses is evident. Among the linear plasmids at least two main groups can be recognized, namely the cytoplasmically and the mitochondrially localized elements.

The linear plasmid pMC3-2 from Morchella conica is structurally related to adenoviruses.

pMC3-2, one of two linear plasmids localised in the mitochondria of the ascomycete Morchella conica, was completely sequenced. It is 6044 bp in size, contains terminal inverted repeats of 713 and 710 bp length and two open reading frames, ORF1 and ORF2, spanning 2706 bp and 918 bp, respectively. ORF1 probably encodes a viral B-type DNA-polymerase. Concerning ORF2, no homology to any other published protein- or DNA-sequence could be detected. According to the structure of DNA-polymerases, linear plasmids can be grouped into two classes reflecting their localisation either in the cytoplasm or within the mitochondria. In general, the structure of plasmid pMC3-2, as well as of other linear plasmids from filamentous fungi, indicates a close relationship of these genetic elements to adenoviruses.

Muscle biopsy--still a matter of methodological considerations.

A method of open muscle biopsy is described which is not so invasive for the patient and not traumatic for the muscle tissue. The biopsy is performed with the patient under local cutaneous anesthesia. The sample can be obtained from a defined part of the muscle. It allows morphological-quantitative evaluation of a sufficient amount of fibers to arrive at reliable results. The advantages of the described method compared with other open and needle biopsy procedures, especially with regard to the method of anesthesia, are discussed.

Neopterin production in inflamed knee joints: high levels in synovial fluids.

Neopterin levels of serum and fluid were determined in 30 patients with inflammatory synovial fluids and in 30 controls with joint effusions induced by trauma or osteoarthritis. Neopterin was significantly elevated in inflammatory fluids. There was no correlation with the acute phase reactants. Neopterin levels were significantly higher in inflammatory fluids than in serum, and vice versa in non-inflammatory conditions. Our results indicate that in arthritis neopterin is produced locally in the joint by monocytes induced by T-cell activation.

Effects of search cost on foraging and feeding: a three-component chain analysis.

An experiment determined whether pigeons minimize number of key pecks per food delivery and maintain their baseline intake of food while key pecking on a three-component chain schedule. Pigeons at either 80% or 100% body weight obtained all their food during baseline and contingency sessions. During baseline sessions, pecks on the left and center keys had no consequences; each peck on the right key activated the feeder. During contingency sessions, pigeons key pecked on a three-component chain schedule simulating components of a foraging chain. In the search component either 3, 9 or 15 key pecks (varied parametrically across blocks of sessions) on the left key produced a stimulus on the middle key, indicating an encounter with either the low-cost prey (3 key pecks) or an equally probable high-cost prey (21 key pecks). In the procurement component the pigeon pecked either: (a) the left key once, thus returning to the search component, or (b) the middle key either 3 or 21 times, which activated the right response key. In the handling component one peck on the right key operated the feeder. The pigeons always procured the low-cost prey and minimized the number of key pecks per hopper by procuring the high-cost prey when the search-cost ratio was high (15 key pecks) but not when it was low (3 key pecks). All pigeons maintained their baselines of eating during contingency sessions by key pecking more frequently and eating more efficiently. The 80% body-weight birds produced higher overall rates of key pecking and eating. These results have implications for ecological theories of optimal foraging and for psychological theories of learned performance.

[Idiopathic megacolon (author's transl)]. / Das idiopathische Megakolon.

The diagnosis of congenital megacolon can only rarely be established in adult cases with dilatation of the rectum and sigma, since the narrow aganglionic segment and increased levels of plasma acetylcholinesterase activity are usually lacking in adult cases,--these findings being typical for congenital megacolon. Idiopathic megacolon thus is the correct diagnosis in most of these adult cases. Surgical removal of the dilated parts of the intestine and end-to-end anastomosis yield satisfactory results, thus a colostomy is not necessary.