Our work and that of others defined mitosis-specific (Rad21 subfamily) and meiosis-specific (Rec8 subfamily) proteins involved in sister chromatid cohesion in several eukaryotes, including humans. Mutation of the fission yeast Schizosaccharomyces pombe rec8 gene was previously shown to confer a number of meiotic phenotypes, including strong reduction of recombination frequencies in the central region of chromosome III, absence of linear element polymerization, reduced pairing of homologous chromosomes, reduced sister chromatid cohesion, aberrant chromosome segregation, defects in spore formation, and reduced spore viability. Here we extend the description of recombination reduction to the central regions of chromosomes I and II. We show at the protein level that expression of rec8 is meiosis specific and that Rec8p localizes to approximately 100 foci per prophase nucleus. Rec8p was present in an unphosphorylated form early in meiotic prophase but was phosphorylated prior to meiosis I, as demonstrated by analysis of the mei4 mutant blocked before meiosis I. Evidence for the persistence of Rec8p beyond meiosis I was obtained by analysis of the mutant mes1 blocked before meiosis II. A human gene, which we designate hrec8, showed significant primary sequence similarity to rec8 and was mapped to chromosome 14. High mRNA expression of mouse and human rec8 genes was found only in germ line cells, specifically in testes and, interestingly, in spermatids. hrec8 was also expressed at a low level in the thymus. Sequence similarity and testis-specific expression indicate evolutionarily conserved functions of Rec8p in meiosis. Possible roles of Rec8p in the integration of different meiotic events are discussed.

IntroductionIn the life cycle of sexually reproducing organisms meiosis halves the chromosome number in the germ line cells and produces haploid gametes. This halving is achieved by two consecutive divisions following a single round of DNA replication. The second (equational) division resembles mitotis: sister chromatids segregate into daughter nuclei. However, the first (reductional) division has unique features. During the first meiotic division homologous chromosomes pair, undergo high levels of recombination, and the resulting chiasma formation assists their segregation into daughter nuclei. In most organisms, pairing of homologous chromosomes in meiotic prophase is accompanied by the formation of synaptonemal complexes (SC). The synaptonemal complex is an evolutionary well-conserved, strictly meiosis specific, proteinaceous structure. In early prophase, after DNA replication axial elements (AE) start to connect the sister chromatids. By the pachytene stage of meiotic prophase, chromosome pairing and synaptonemal complex development culminate in the formation of a tripartite structure: the axial elements (now called lateral elements, LE) are connected by a central component (for reviews, see Zickler and Kleckner, 1999;Roeder, 1997;Kleckner, 1996).The fission yeast Schizosaccharomyces pombe is a haploid, unicellular eukaryote. Naturally, S. pombe cells undergo meiosis directly after mating of two cells of opposite matingtype (zygotic meiosis). However, diploid cells heterozygous for mating-type can be maintained, and synchronous meiosis can be induced by shifting the culture to nitrogen-free medium (azygotic meiosis) (Egel, 1973;Egel and Egel-Mitani, 1974). Meiosis in fission yeast has unusual features. In prophase, the meiotic nucleus oscillates between the cell poles (Chikashige et al., 1994). These movements confer an elongated shape to the nucleus [horse-tail nucleus (Robinow, 1977)], and are led by the SPB and the attached telomere cluster (Chikashige et al., 1994;Chikashige et al., 1997). Thus, the bouquet structure of chromosomes bundled at the telomeres is maintained during the whole meiotic prophase in fission yeast. Homologous chromosome pairing and recombination occur during horse-tail movements. Mutants impaired in telomere clustering or nuclear movement show decreased homologous pairing and recombination, indicating the importance of these events in homolog juxtaposition (Shimanuki et al., 1997;Cooper et al., 1998;Nimmo et al., 1998;Yamamoto et al., 1999). Fission yeast is highly proficient in meiotic recombination but shows no crossover interference (Munz, 1994).It has been long known that fission yeast does not form synaptonemal complexes. Instead, filamentous structures (linear elements) appear in meiotic prophase. They resemble the axial cores of other eukaryotes (Olson et al., 1978;Hirata and Tanaka, 1982). The adaptation of the nuclear spreading technique to fission yeast made possible a detailed analysis of linear element formation in meiotic time-course experiments (Bähler et al., 1993). ...

The aim of the study was to demonstrate that the bZIP-type transcription factor AtfA regulates different types of stress responses in Aspergillus nidulans similarly to Atf1, the orthologous 'all-purpose' transcription factor of Schizosaccharomyces pombe. Heterologous expression of atfA in a S. pombe Deltaatf1 mutant restored the osmotic stress tolerance of fission yeast in surface cultures to the same level as recorded in complementation studies with the atf1 gene, and a partial complementation of the osmotic and oxidative-stress-sensitive phenotypes was also achieved in submerged cultures. AtfA is therefore a true functional ortholog of fission yeast's Atf1. As demonstrated by RT-PCR experiments, elements of both oxidative (e.g. catalase B) and osmotic (e.g. glycerol-3-phosphate dehydrogenase B) stress defense systems were transcriptionally regulated by AtfA in a stress-type-specific manner. Deletion of atfA resulted in oxidative-stress-sensitive phenotypes while the high-osmolarity stress sensitivity of the fungus was not affected significantly. In A. nidulans, the glutathione/glutathione disulfide redox status of the cells as well as apoptotic cell death and autolysis seemed to be controlled by regulatory elements other than AtfA. In conclusion, the orchestrations of stress responses in the aspergilli and in fission yeast share several common features, but further studies are needed to answer the important question of whether a fission yeast-like core environmental stress response also operates in the euascomycete genus Aspergillus.

The evolutionarily conserved Mre11/Rad50/Nbs1 (MRN) complex is involved in various aspects of meiosis. Whereas available evidence suggests that the Mre11 nuclease activity might be responsible for Spo11 removal in Saccharomyces cerevisiae, this has not been confirmed experimentally. This study demonstrates for the first time that Mre11 (Schizosaccharomyces pombe Rad32 Mre11 ) nuclease activity is required for the removal of Rec12Spo11 . Furthermore, we show that the CtIP homologue Ctp1 is required for Rec12 Spo11 removal, confirming functional conservation between Ctp1CtIP and the more distantly related Sae2 protein from Saccharomyces cerevisiae. Finally, we show that the MRN complex is required for meiotic recombination, chromatin remodeling at the ade6-M26 recombination hot spot, and formation of linear elements (which are the equivalent of the synaptonemal complex found in other eukaryotes) but that all of these functions are proficient in a rad50S mutant, which is deficient for Rec12 Spo11 removal. These observations suggest that the conserved role of the MRN complex in these meiotic functions is independent of Rec12 Spo11 removal.In meiosis, one round of DNA replication is followed by two nuclear divisions that divide the genetic material equally over four haploid daughter cells. Meiotic recombination contributes to genetic diversity and is essential for correct disjunction of the homologous chromosomes in the first meiotic division. In meiotic prophase, after meiosis-specific DNA replication, the homologous chromosomes pair and recombine. In the following two nuclear divisions, the homologous chromosomes (meiosis I) and the sister chromatids (meiosis II) are segregated. The study of meiosis in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe has greatly contributed to our understanding of various meiotic processes. Because these model organisms are as distantly related to each other as to animals (35), detailed studies of similarities and differences between meiotic mechanisms in these yeasts are informative as to which mechanisms are conserved in higher eukaryotes.The evolutionarily conserved Mre11/Rad50/Nbs1 (MRN) protein complex is involved in a wide range of early responses to DNA damage. Mutations in Nbs1 and Mre11 are responsible for the cancer-prone human disorders Nijmegen breakage syndrome and ataxia telangiectasia-like disorder. Central in this complex is the Mre11 nuclease, which is thought to be involved in double-strand break (DSB) end resection and DSB signaling (reviewed in reference 40).The MRN complex is also involved in multiple aspects of meiosis. In S. cerevisiae, meiotic recombination is initiated by the topoisomerase-like protein Spo11 (17), which creates a DSB in the DNA. Spo11 remains covalently bound to the 5Ј ends of the break (17) and is removed by endonucleolytic cleavage (28) to initiate subsequent DSB end resection and meiotic recombination. Meiotic DSB formation is abolished in S. cerevisiae MRN null mutants (6, 16). In an S. cerevisiae rad50S point mutant (a...

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In the 5 years since the 2010 Ajka red mud spill (Hungary), there have been 46 scientific studies assessing the key risks and impacts associated with the largest single release of bauxite-processing residue (red mud) to the environment. These studies have provided insight into the main environmental concerns, as well as the effectiveness of remedial efforts that can inform future management of red mud elsewhere. The key immediate risks after the spill were associated with the highly caustic nature of the red mud slurry and fine particle size, which once desiccated, could generate fugitive dust. Studies on affected populations showed no major hazards identified beyond caustic exposure, while red mud dust risks were considered equal to or lesser than those provided by urban dusts of similar particle size distribution. The longer-term environmental risks were related to the saline nature of the spill material (salinization of inundated soils) and the release and the potential cycling of oxyanion-forming metals and metalloids (e.g., Al, As, Cr, Mo, and V) in the soil-water environment. Of these, those that are soluble at high pH, inefficiently removed from solution during dilution and likely to be exchangeable at ambient pH are of chief concern (e.g., Mo and V). Various ecotoxicological studies have identified negative impacts of red mud-amended soils and sediments at high volumes (typically [5 %) on different test organisms, with some evidence of molecularlevel impacts at high dose (e.g., genotoxic effects on plants and mice). These data provide a valuable database to inform future toxicological studies for red mud. However, extensive management efforts in the aftermath of the spill greatly limited these exposure risks through leachate neutralization and red mud recovery from the affected land. Monitoring of affected soils, stream sediments, waters and aquatic biota (fungi, invertebrates and fish) have all shown a very rapid recovery toward prespill conditions. The accident also prompted research that has also highlighted potential benefits of red mud use for critical raw material recovery (e.g., Ga, Co, V, rare earths, inform), carbon sequestration, biofuel crop production, and use as a soil ameliorant.

Since the world economy has been confronted with an increasing risk of supply shortages of critical raw materials (CRMs), there has been a major interest in identifying alternative secondary sources of CRMs. Bauxite residues from alumina production are available at a multi‐million tonnes scale worldwide. So far, attempts have been made to find alternative re‐use applications for bauxite residues, for instance in cement / pig iron production. However, bauxite residues also constitute an untapped secondary source of CRMs. Depending on their geological origin and processing protocol, bauxite residues can contain considerable amounts of valuable elements. The obvious primary consideration for CRM recovery from such residues is the economic value of the materials contained. However, there are further benefits from re‐use of bauxite residues in general, and from CRM recovery in particular. These go beyond monetary values (e.g. reduced investment / operational costs resulting from savings in disposal). For instance, benefits for the environment and health can be achieved by abatement of tailing storage as well as by reduction of emissions from conventional primary mining. Whereas certain tools (e.g. life‐cycle analysis) can be used to quantify the latter, other benefits (in particular sustained social and technological development) are harder to quantify. This review evaluates strategies of bauxite residue re‐use / recycling and identifies associated benefits beyond elemental recovery. Furthermore, methodologies to translate risks and benefits into quantifiable data are discussed. Ultimately, such quantitative data are a prerequisite for facilitating decision‐making regarding bauxite residue re‐use / recycling and a stepping stone towards developing a zero‐waste alumina production process. © 2018 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

BACKGROUND Red mud is a by‐product of alumina extraction from bauxite by the Bayer process produced in the billion tons scale worldwide. Red muds, or more generally bauxite residues, are regarded as waste, but may potentially be valuable sources of critical raw materials (CRM). In the present study both conventional extracting agents (mineral acids) and small molecular weight complexing agents (organic acids) were evaluated regarding their efficiency to extract CRM such as rare earth elements (REEs) from red mud. On a molar base, highest extraction efficiencies for REEs were achieved using HCl compared with the other acids investigated. Consequently, an experimental design approach was used to determine optimal conditions for CRM extraction using HCl. Instead of maximizing the extraction of a number of selected metals, the maximum economic potential as the sum of all metals (total metal extracted × economic value of the respective metal) was chosen as the application relevant response variable. Four explanatory variables (i.e. HCl concentration, contact time, temperature and slurry concentration) were used. RESULTS Optimal conditions maximizing the economic potential were predicted for 5.98 mol L−1 HCl, 21 h contact time, 50°C, and 56.7 g L−1 slurry concentration. Indeed, experimentally determined economic potential corresponded well (71% of predicted) with the predictions, allowing a maximum recovery of 297.6 US $ t−1. CONCLUSION Though the studied red muds were relatively low in CRM concentrations, the systematic approach developed here allows straightforward transfer to other red muds, harnessing the potential of the latter as important secondary source for CRM. © 2017 Society of Chemical Industry