Fungal transformation of selenium and tellurium located in a volcanogenic sulfide deposit

Microbial reduction of soluble selenium (Se) or tellurium (Te) species results in immobilization as elemental forms and this process has been employed in soil bioremediation. However, little is known of direct and indirect fungal interactions with Se-/Te-bearing ores. In this research, the ability of Phoma glomerata to effect transformation of selenite and tellurite was investigated including interaction with Se and Te present in sulfide ores from the Kisgruva Proterozoic volcanogenic deposit. Phoma glomerata could precipitate elemental Se and Te as nanoparticles, intracellularly and extracellularly, when grown with selenite or tellurite. The nanoparticles possessed various surface capping molecules, with formation being influenced by extracellular polymeric substances. The presence of sulfide ore also affected the production of exopolysaccharide and protein. Although differences were undetectable in gross Se and Te ore levels before and after fungal interaction using X-ray fluorescence, laser ablation inductively coupled plasma mass spectrometry of polished flat ore surfaces revealed that P. glomerata could effect changes in Se/Te distribution and concentration indicating Se/Te enrichment in the biomass. These findings provide further understanding of fungal roles in metalloid transformations and are relevant to the geomicrobiology of environmental metalloid cycling as well as informing applied approaches for Se and Te immobilization, biorecovery or bioremediation.     

Drosophila Tubulin-Specific Chaperone E Recruits Tubulin around Chromatin to Promote Mitotic Spindle Assembly

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Space-time decoupling in the branching process in the mutant étoile of the filamentous brown alga Ectocarpus siliculosus

Ectocarpus siliculosus is being developed as a model organism for brown algal genetics and genomics.^1,2 Brown algae are phylogenetically distant from the other multicellular phyla (green lineage, red algae, fungi and metazoan)³ and therefore might offer the opportunity to study novel and alternative developmental processes that lead to the establishment of multicellularity. E. siliculosus develops as uniseriate filaments, thereby displaying one of the simplest architectures among multicellular organisms.⁴ The young sporophyte grows as a primary filament and then branching occurs, preferentially at the center of the filament. We recently described the first morphogenetic mutant étoile (etl) in a brown alga, produced by UVB mutagenesis in E. siliculosus.⁵ We showed that a single recessive mutation was responsible for a defect in both cell differentiation and the very early branching pattern (first and second branch emergences). Here, we supplement this study by reporting the branching defects observed subsequently, i.e. for the later stages corresponding to the emergence of up to the first six secondary filaments, and we show that the branching process is composed of at least two distinct components: time and position.   The developmental pattern of E. siliculosus is characterized by a very high level of morphological plasticity.⁶ Observations followed by statistical analyses allowed analyzing the morphometric features accompanying the establishment of the branching pattern in the mutant étoile, compared with the wild type (WT) organism (strain Ec32). The branching pattern can be deciphered in two main components: (1) the timing of branching and (2) the position of branching.