Ferricrocin synthesis in Magnaporthe grisea and its role in pathogenicity in rice

Iron is an essential element for the growth of nearly all organisms. In order to overcome the problem of its low bioavailability, microorganisms (including fungi) secrete siderophores, high-affinity iron chelators. As the acquisition of iron is also a key step in infection processes, siderophores have been considered as potential virulence factors in several host–pathogen interactions. Most fungi produce siderophores of the hydroxamate-type, which are synthesized by non-ribosomal peptide synthetases (NRPSs). Magnaporthe grisea , the causal agent of rice blast disease, produces ferricrocin as intracellular storage siderophore and excretes coprogens. In the M. grisea genome we identified SSM1 , an NRPS gene, and a gene encoding an l -ornithine N5-monooxygenase ( OMO1 ) that is clustered with SSM1 and responsible for catalysing the first step in siderophore biosynthesis, the N⁵ hydroxylation of ornithine. Disruption of SSM1 confirmed that the gene encodes ferricrocin synthetase. Pathogenicity of these mutants towards rice was reduced, suggesting a role of this siderophore in pathogenicity of M. grisea .     

A method for in vitro production of conidia of Elsinoe veneta and the inoculation of raspberry cultivars

Conidia of two isolates of Elsinoe veneta were consistently produced in vitro by a 3-stage culture system in which sparsely sporulating microcolonies produced on corn meal agar were used to ‘seed’ Czapek-Dox V8 juice agar. E. veneta then sporulated on this medium if dises were floated mycelium uppermost on sterile distilled water for 24 h at 25°C. Both isolates also produced microconidia in vitro. Only the growing apices of raspberry canes were susceptible to infection. Of 12 genotypes inoculated in the glasshouse, a red raspberry derivative of Rubus coreanus, EMRS 2769/9, was the most resistant and the black raspberry selection SCRI 815286 and cv. Malling Delight were the most susceptible. Of four red raspberry cultivars inoculated in the field cv. Malling Orion was the most susceptible. Inoculated flowers and developing fruits produced malformed fruits because infected drupelets were smaller or slower to ripen than uninfected ones.     

The structure of the cells of the mesophyll and parenchymatous bundle sheath of the Gramineae

By a comparison of the ultrastructural features of the parenchymatous bundle sheath and the mesophyll it can be shown that the grasses can be divided into a number of groups roughly corresponding to those proposed by Brown, viz. Pooid, Eragrostoid, Panicoid, Arundinoid, Bambusoid and Aristidoid. In particular the ultrastructural features strengthen the grounds for separating the eragrostoid type of leaf anatomy from the panicoid type. These ultrastructural differences seem to be correlated with differences in photosynthetic pathways, and, where they do not correlate with the taxonomic divisions, neither do the photosynthetic pathways. The correlation with a taxonomy based on microcharacters as well as macroscopic characters is generally good except in the case of "Phragmitiform" grasses, and in particular the tribe Danthonieae, which seems to require a serious detailed extensive investigation.     

Multiple Pleistocene refugia and Holocene range expansion of an abundant southwestern American desert plant species (Melampodium leucanthum,Asteraceae)

Pleistocene climatic fluctuations had major impacts on desert biota in southwestern North America. During cooler and wetter periods, drought‐adapted species were isolated into refugia, in contrast to expansion of their ranges during the massive aridification in the Holocene. Here, we use Melampodium leucanthum (Asteraceae), a species of the North American desert and semi‐desert regions, to investigate the impact of major aridification in southwestern North America on phylogeography and evolution in a widespread and abundant drought‐adapted plant species. The evidence for three separate Pleistocene refugia at different time levels suggests that this species responded to the Quaternary climatic oscillations in a cyclic manner. In the Holocene, once differentiated lineages came into secondary contact and intermixed, but these range expansions did not follow the eastwardly progressing aridification, but instead occurred independently out of separate Pleistocene refugia. As found in other desert biota, the Continental Divide has acted as a major migration barrier for M. leucanthum since the Pleistocene. Despite being geographically restricted to the eastern part of the species’ distribution, autotetraploids in M. leucanthum originated multiple times and do not form a genetically cohesive group.     

Characterization of 28 microsatellite loci for the butterfly Bicyclus anynana

We present 28 polymorphic microsatellite loci, including a sex‐linked W‐chromosome marker, for the Afrotropical butterfly, Bicyclus anynana. Our primary motivation to develop these markers was to apply them in quantitative trait loci (QTL) mapping studies. A technique is also proposed that may be useful in avoiding redundant sequences which are common in lepidopteran‐enriched libraries. Pedigree analysis was performed to test Mendelian segregation of the markers and to address the issue of null alleles.     

Studies in the ecology of coastal heath in New South Wales

Effects of heating dry seed were investigated in Banksia serratifolia and B. ericifolia. Seeds were inviable after 7 min exposure at 150°C or higher temperatures but remained viable after exposure at 100°C and lower temperatures. Imbibed seeds show no dormancy, and seeds survive fire insulated from heat in the thick woody follicles which may persist unopened for several years on the parent plant but open following fire. Effects of nutritional supplements were observed in the seed germination and seedling survival and growth of Banksia serratifolia, B. aspleniifolia and B. ericifolia. Germination with radicle and hypocotyls extension was not significantly affected by a wide range of mineral nutrient regimes. In pot experiments using a heath soil seedling survival and growth were adversely affected by moderate additions of phosphate with surviving seedlings showing toxicity symptoms and poor development of proteoid roots. Moderate supplements of potassium had no adverse effect, and in B. serratifolia and B. ericifolia lessened the adverse effects of phosphate addition. The slow growth of the seedlings accords with the normal low nutrient availability in heath soils but seedlings show little capacity for rapid exploitation of any temporary increase of available nutrients after fire.     

Exceptionally well‐preserved isolated eyes from Cambrian ‘Orsten’ fossil assemblages of Sweden

Abstract: Eyes other than those of trilobites are rarely preserved in the fossil record. We describe here a set of six tiny, isolated, three‐dimensionally preserved compound eyes. These secondarily phosphatized eyes were etched from ‘Orsten’ limestone nodules dated to the Agnostus pisiformis Biozone from the Cambrian Alum Shale Formation of Sweden. The ovoid eyes arise from an elongated stalk, their surface being covered by a mosaic of regular and hexagonal‐shaped facets representing the surface of ommatidia. Facet size and pattern change within the same specimen from the posterior to the anterior end. With regard to some morphological criteria, we grouped the material in two different morphotypes, type A and B, the first being represented by specimens of two different developmental stages. From stage to stage, mostly growth in overall size and addition of new ommatidia was noticed. Among the meiobenthic ‘Orsten’ arthropods, only the crustacean Henningsmoenicaris scutula has been described as possessing stalked eyes, but the eyes of the largest specimen with preserved eyes of this species are much smaller than the new eyes and do not display any kind of ommatidia on their visual surface. However, fragments of larger specimens of H. scutula and the co‐occurrence of this species with the new isolated eyes in the sieving residues make it likely that the latter belong to this species but belong to more advanced stages than those described previously of H. scutula. Ontogenetically, the eye stalks of this fossil crustacean elongate progressively, while the regular hexagonal facets, lacking in early stages, appear later on.     

Functional morphology,ontogeny and evolution of mantis shrimp‐like predators in the Cambrian

Abstract: We redescribe the morphology of Yohoia tenuis (Chelicerata sensu lato) from the Cambrian Burgess Shale Lagerstätte. The morphology of the most anterior, prominent, so‐called great appendage changes throughout ontogeny. While its principal morphology remains unaltered, the length ratios of certain parts of the great appendage change significantly. Furthermore, it possesses a special jack‐knifing mechanism, i.e. an elbow joint: the articulation between the distal one of the two peduncle elements and the most proximal of the four spine‐bearing claw elements. This morphology might have enabled the animal to hunt like a modern spearer‐type mantis shrimp, an analogy enhanced by the similarly large and protruding eyes. For comparison, details of specimens of selected other great‐appendage arthropods from the Lower Cambrian Chengjiang Lagerstätte have been investigated using fluorescence microscopy. This revealed that the morphology of the great appendage of Y. tenuis is much like that of the Chengjiang species Fortiforceps foliosa and Jianfengia multisegmentalis. The morphology of the great appendage of the latter is even more similar to the morphology developed in early developmental stages of Y. tenuis, while the morphology of the great appendage of F. foliosa is more similar to that of later developmental stages of Y. tenuis. The arrangement of the elbow joint supports the view that the great appendage evolved into the chelicera of Chelicerata sensu stricto, as similar joints are found in various ingroup taxa such as Xiphosura, Opiliones or Palpigradi. With this, it also supports the interpretation of the great appendage to be homologous with the first appendage of other arthropods.