Aerobic spore-forming bacteria as detrimental infectants in plant tissue cultures

Summary Aerobic spore-forming bacteria were isolated from plant tissue cultures from a commercial plant cultivation station. Bacillus circulans was found to be a detrimental infectant as a serious consequence of the heat-resistance of the endospores of these bacteria. They were extremely motile, utilized several growth-promoting factors, and could be eliminated by early microscopical identification, killing by heat treatment, or by using antibiotics or disinfecants.Dedicated to Professor Dr. Gustav Kortüm on the occasion of his 80th birthday     

An analysis of the relative activities of a number of promoter constructs from genes which are expressed during late pollen development as determined by particle bombardment

Summary The promoters of a tobacco actin gene, a tobacco pectate lyase, a tobacco and maize polygalacturonase and aBrassica S-locus related gene have been fused to the-glucuronidase reporter gene and their activities determined by biolistic transient assay in tobacco pollen. In stably transformed tobacco all the transgenes with the exception of Cauliflower Mosaic Virus-35S--glucuronidase appear to express efficiently in maturing pollen. Transient assay analysis showed that the tobacco pectate lyase and the polygalacturonase constructs were 8x more active than the tobacco actin construct, and that the tobacco polygalacturonase construct was some 33x more active than the maize polygalacturonase construct. Constructional manipulations that altered the lengths of the 5-untranslated leaders including one which resulted in the removal of a 490 bp leader intron had little effect on the observed level of expression. However, the alteration of the context of the ATG from A/TnnATGG to CnnATGT resulting in a 70% reduction in the observed levels of activity, was obtained with the pectate lyase and polygalacturonase promoters. An identical reductional was also observed in transgenic plant populations transformed with the polygalacturonase transgenes.Abbreviations GUS -glucuronidase - LUC luciferase - NosTer nopaline synthase terminator - CaMV Cauliflower Mosaic Virus - UTL untranslated leader - PCR polymerase chain reaction - PG polygalacturonase - Npg tobacco polygalacturonase - Pl pectate lyase - Ac actin     

DNA sequences of the two homoeologous SLR1 genes of Brassica napus cv Westar

The DNA sequence data reported have been lodged in the Genbank, EMBL and DDBJ databases under the accession numbers Z21609 and Z26914     

Characterization of Herpetosiphon spec. —A gliding filamentous bacterium from bulking sludge

Summary Filamentous bacteria were isolated from bulking activated sludge and identified as Herpetosiphon spec. The Gram-negative filaments are more than 500 m long and they show gliding motility. The bacteria grown in artificial media (J- or EC-medium), in shaken cultures yield about 3 g cells per liter. Optimum growth was observed at 25°C and pH 7.2. The colonies are either uncoloured or bright red depending on the cultivation medium. The isolated bacteria exhibit lytic activity towards cells of Escherichia coli and Klebsiella pneumoniae. The G+C ratio of the five strains from different bulking sludge samples was found to be between 48.7 moles% and 49.0 moles%.     

Global change‐driven effects on dissolved organic matter composition: Implications for food webs of northern lakes

Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial–aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)—the messenger between terrestrial and lake ecosystems—with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change‐driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice‐out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans.     

Efficient large-scale development of microsatellites for marker and mapping applications in<Emphasis Type="Italic"> Brassica</Emphasis> crop species

A set of 398 simple sequence repeat markers (SSRs) have been developed and characterised for use with genetic studies of Brassica species. Small-insert (250–900 bp) genomic libraries from Brassica rapa, B. nigra, B. oleracea and B. napus, highly enriched for dinucleotide and trinucleotide SSR motifs, were constructed. Screening the clones with a mixture of oligonucleotide repeat probes revealed positive hybridisation to between 75% and 90% of the clones. Of these, 1,230 were sequenced. Primer pairs were designed for 398 SSR clones, and of these, 270 (67.8%) amplified a PCR product of the expected size in their focal and/or closely related species. A further screen of 138 primers pairs that produced a PCR product in B. napus germplasm found that 86 (62.3%) revealed length polymorphisms within at least one line of a test array representing the four Brassica species. The results of this screen were used to identify 56 SSRs and were combined with 41 SSRs that had previously shown polymorphism between the parents of a B. napus mapping population. These 97 SSR markers were mapped relative to a framework of RFLP markers and detected 136 loci over all 19 linkage groups of the oilseed rape genome.Electronic Supplementary Material Supplementary material is available in the online version of this article at Communicated by O. Savolainen