Nuclear Functions of KaeA, a Subunit of the KEOPS Complex in Aspergillus nidulans.

Kae1 is a subunit of the highly evolutionarily conserved KEOPS/EKC complex, which is involved in universal (t6A37) tRNA modification. Several reports have discussed the participation of this complex in transcription regulation in yeast and human cells, including our previous observations of KaeA, an Aspergillus nidulans homologue of Kae1p. The aim of this project was to confirm the role of KaeA in transcription, employing high-throughput transcriptomic (RNA-Seq and ChIP-Seq) and proteomic (LC-MS) analysis. We confirmed that KaeA is a subunit of the KEOPS complex in A. nidulans. An analysis of kaeA19 and kaeA25 mutants showed that, although the (t6A37) tRNA modification is unaffected in both mutants, they reveal significantly altered transcriptomes compared to the wild type. The finding that KaeA is localized in chromatin and identifying its protein partners allows us to postulate an additional nuclear function for the protein. Our data shed light on the universal bi-functional role of this factor and proves that the activity of this protein is not limited to tRNA modification in cytoplasm, but also affects the transcriptional activity of a number of nuclear genes. Data are available via the NCBI's GEO database under identifiers GSE206830 (RNA-Seq) and GSE206874 (ChIP-Seq), and via ProteomeXchange with identifier PXD034554 (proteomic).

Human-mediated dispersal of cats in the Neolithic Central Europe.

Archeological and genetic evidence suggest that all domestic cats derived from the Near Eastern wildcat (Felis silvestris lybica) and were first domesticated in the Near East around 10,000 years ago. The spread of the domesticated form in Europe occurred much later, primarily mediated by Greek and Phoenician traders and afterward by Romans who introduced cats to Western and Central Europe around 2000 years ago. We investigated mtDNA of Holocene Felis remains and provide evidence of an unexpectedly early presence of cats bearing the Near Eastern wildcat mtDNA haplotypes in Central Europe, being ahead of Roman period by over 2000 years. The appearance of the Near Eastern wildcats in Central Europe coincides with the peak of Neolithic settlement density, moreover most of those cats belonged to the same mtDNA lineages as those domesticated in the Near East. Thus, although we cannot fully exclude that the Near Eastern wildcats appeared in Central Europe as a result of introgression with European wildcat, our findings support the hypothesis that the Near Eastern wildcats spread across Europe together with the first farmers, perhaps as commensal animals. We also found that cats dated to the Neolithic period belonged to different mtDNA lineages than those brought to Central Europe in Roman times, this supports the hypothesis that the gene pool of contemporary European domestic cats might have been established from two different source populations that contributed in different periods.

[Gene editing]. / Edytowanie genów

Development of the gene engineering techniques has raised worries that they will be used for construction of organism endangering humans and environment. In 1975 at the Asilomar conference, geneticists from many countries decided that genetic engineering brings more benefits than threats. In last years a new CRISPR-Cas technique emerged . It allows to make the precise changes in genomes, e.g. to inactivate particular genes or to replace mutated genes by their wild-type alleles. Inactivation in mice of genes corresponding to those whose mutations cause the genetic diseases in man allows to get model organisms for studying the etiology of given disease and for working out the methods of its curing. This technique can be applied for repairing genes whose mutations result in metabolic diseases and cancer. Some voices were raised that the technique can be potentially used for the "improvement" of man, what would create many ethical and social problems. Geneticists, ethicists and lawyers gathered in 2015 at the Washington conference, discussed these problems and proposed rules for their solving.

Microsatellite Mutation Rate in Atlantic Sturgeon (Acipenser oxyrinchus).

Understanding mutation rates can greatly extend the utility of population and conservation genetic analyses. Herein, we present an estimate of genome-wide microsatellite mutation rate in Atlantic sturgeon (Acipenser oxyrinchus) based on parent-offspring transmission patterns. We screened 307 individuals for parentage and mutation-rate analysis applying 43 variable markers. Out of 13228 allele transfers, 11 mutations were detected, producing a mutation rate of 8.3 × 10-4 per locus per generation (95% confidence interval: 1.48 × 10-3, 4.15 × 10-4). Single-step mutations predominated and there were trends toward mutations in loci with greater polymorphism and allele length. Two of the detected mutations were most probably cluster mutations, being identified in 12 and 28 sibs, respectively. Finally, we observed evidences of polyploidy based on the sporadic presence of 3 or 4 alleles per locus in the genotyped individuals, supporting previous reports of incomplete diploidization in Atlantic sturgeon.

Synchronous genetic turnovers across Western Eurasia in Late Pleistocene collared lemmings.

Recent palaeogenetic studies indicate a highly dynamic history in collared lemmings (Dicrostonyx spp.), with several demographical changes linked to climatic fluctuations that took place during the last glaciation. At the western range margin of D. torquatus, these changes were characterized by a series of local extinctions and recolonizations. However, it is unclear whether this pattern represents a local phenomenon, possibly driven by ecological edge effects, or a global phenomenon that took place across large geographical scales. To address this, we explored the palaeogenetic history of the collared lemming using a next-generation sequencing approach for pooled mitochondrial DNA amplicons. Sequences were obtained from over 300 fossil remains sampled across Eurasia and two sites in North America. We identified five mitochondrial lineages of D. torquatus that succeeded each other through time across Europe and western Russia, indicating a history of repeated population extinctions and recolonizations, most likely from eastern Russia, during the last 50 000 years. The observation of repeated extinctions across such a vast geographical range indicates large-scale changes in the steppe-tundra environment in western Eurasia during the last glaciation. All Holocene samples, from across the species' entire range, belonged to only one of the five mitochondrial lineages. Thus, extant D. torquatus populations only harbour a small fraction of the total genetic diversity that existed across different stages of the Late Pleistocene. In North American samples, haplotypes belonging to both D. groenlandicus and D. richardsoni were recovered from a Late Pleistocene site in south-western Canada. This suggests that D. groenlandicus had a more southern and D. richardsoni a more northern glacial distribution than previously thought. This study provides significant insights into the population dynamics of a small mammal at a large geographical scale and reveals a rather complex demographical history, which could have had bottom-up effects in the Late Pleistocene steppe-tundra ecosystem.

RrmA regulates the stability of specific transcripts in response to both nitrogen source and oxidative stress.

Differential regulation of transcript stability is an effective means by which an organism can modulate gene expression. A well-characterized example is glutamine signalled degradation of specific transcripts in Aspergillus nidulans. In the case of areA, which encodes a wide-domain transcription factor mediating nitrogen metabolite repression, the signal is mediated through a highly conserved region of the 3' UTR. Utilizing this RNA sequence we isolated RrmA, an RNA recognition motif protein. Disruption of the respective gene led to loss of both glutamine signalled transcript degradation as well as nitrate signalled stabilization of niaD mRNA. However, nitrogen starvation was shown to act independently of RrmA in stabilizing certain transcripts. RrmA was also implicated in the regulation of arginine catabolism gene expression and the oxidative stress responses at the level of mRNA stability. ΔrrmA mutants are hypersensitive to oxidative stress. This phenotype correlates with destabilization of eifE and dhsA mRNA. eifE encodes eIF5A, a translation factor within which a conserved lysine is post-translationally modified to hypusine, a process requiring DhsA. Intriguingly, for specific transcripts RrmA mediates both stabilization and destabilization and the specificity of the signals transduced is transcript dependent, suggesting it acts in consort with other factors which differ between transcripts.

Locals, resettlers, and pilgrims: a genetic portrait of three pre-Columbian Andean populations.

The common practice of resettlement and the development of administrative and ceremonial systems shaped the population landscape of the Andean region under the Inca rule. The area surrounding Coropuna and Solimana volcanoes, in the Arequipa region (Peru), carried a high-density, multiethnic population. We studied the genetic variation among three pre-Columbian populations from three functionally diverse archaeological sites excavated in this region. By analyzing the genetic composition of a large ceremonial center (Acchaymarca), an isolated pastoral settlement (Tompullo 2), and an agricultural settlement characterized by architectural features rare in the region (Puca), we investigated the patterns of population movements and the distribution of genetic diversity. We obtained mitochondrial DNA sequences for 25 individuals and autosomal microsatellite profiles for 20 individuals from Acchaymarca and Puca sites. These were compared with previously published genetic data for Tompullo 2 and other pre-Columbian populations. We found differences among the genetic portraits of the three populations, congruent with the archaeologically described functions and characteristics of the sites. The Acchaymarca population had the highest genetic diversity and possessed the lowest number of unique mtDNA haplotypes. The Tompullo 2 population exhibited the lowest level of genetic diversity. The Puca population was distinct from the other two populations owing to a high frequency of haplogroup A haplotypes, what potentially explains the non-local character of the burial architecture. Our analyses of microsatellite data suggest that gene flow between sites was mostly mediated by females, which is consistent with ethnohistorical knowledge of the social organization of the pre-Columbian communities.

The GATA factors AREA and AREB together with the co-repressor NMRA, negatively regulate arginine catabolism in Aspergillus nidulans in response to nitrogen and carbon source.

The filamentous fungus Aspergillus nidulans can utilize arginine both as a nitrogen and carbon source. Analysis of areA and areB single and double mutants has shown that the two GATA transcription factors AREA and AREB negatively regulate the expression of arginine catabolism genes agaA and otaA under nitrogen repressing conditions. AREA is necessary for the ammonium repression of agaA and otaA under carbon repressing conditions, while AREB is involved under carbon-limiting conditions. The ability of both AREA and AREB to sense the status of carbon metabolism is most probably dependent on NMRA, and not on the transcription factor CREA, which mediates general carbon catabolite repression in A. nidulans. NMRA is a co-repressor which has previously been shown to bind the C-terminus of AREA and inhibits its activity under conditions of nitrogen sufficiency, in response to high intracellular glutamine levels. We therefore propose a novel function for NMRA, the modulation of AREA and AREB activity in response to the carbon status of the cell.

Ancient DNA reveals kinship burial patterns of a pre-Columbian Andean community.

BACKGROUND: A detailed genetic study of the pre-Columbian population inhabiting the Tompullo 2 archaeological site (department Arequipa, Peru) was undertaken to resolve the kin relationships between individuals buried in six different chullpas. Kin relationships were an important factor shaping the social organization in the pre-Columbian Andean communities, centering on the ayllu, a group of relatives that shared a common land and responsibilities. The aim of this study was to evaluate whether this Andean model of a social organization had an influence on mortuary practices, in particular to determine whether chullpas served as family graves. RESULTS: The remains of forty-one individuals were analyzed with both uniparental (mtDNA, Y-chromosome) and biparental (autosomal microsatellites) markers. Reproducible HVRI sequences, autosomal and Y chromosomal STR profiles were obtained for 24, 16 and 11 individuals, respectively. Mitochondrial DNA diversity was comparable to that of ancient and contemporary Andean populations. The Tompullo 2 population exhibited the closest relationship with the modern population from the same region. A kinship analysis revealed complex pattern of relations within and between the graves. However mean relatedness coefficients regarding the pairs of individuals buried in the same grave were significantly higher than those regarding pairs buried in different graves. The Y chromosome profiles of 11 males suggest that only members of one male line were buried in the same grave. CONCLUSIONS: Genetic investigation of the population that inhabited Tompullo 2 site shows continuity between pre-Columbian and modern Native Amerindian populations inhabiting the Arequipa region. This suggests that no major demographic processes have influenced the mitochondrial DNA diversity of these populations during the past five hundred years. The kinship analysis involving uni- and biparental markers suggests that the community that inhabited the Tompullo 2 site was organized into extended family groups that were buried in different graves. This finding is in congruence with known models of social organization of Andean communities.

The role of the GATA transcription factor AreB in regulation of nitrogen and carbon metabolism in Aspergillus nidulans.

In Aspergillus nidulans, nitrogen and carbon metabolism are under the control of wide-domain regulatory systems, including nitrogen metabolite repression, carbon catabolite repression and the nutrient starvation response. Transcriptomic analysis of the wild type strain grown under different combinations of carbon and nitrogen regimes was performed, to identify differentially regulated genes. Carbon metabolism predominates as the most important regulatory signal but for many genes, both carbon and nitrogen metabolisms coordinate regulation. To identify mechanisms coordinating nitrogen and carbon metabolism, we tested the role of AreB, previously identified as a regulator of genes involved in nitrogen metabolism. Deletion of areB has significant phenotypic effects on the utilization of specific carbon sources, confirming its role in the regulation of carbon metabolism. AreB was shown to regulate the expression of areA, tamA, creA, xprG and cpcA regulatory genes suggesting areB has a range of indirect, regulatory effects. Different isoforms of AreB are produced as a result of differential splicing and use of two promoters which are differentially regulated by carbon and nitrogen conditions. These isoforms are likely to be functionally distinct and thus contributing to the modulation of AreB activity.

KAEA (SUDPRO), a member of the ubiquitous KEOPS/EKC protein complex, regulates the arginine catabolic pathway and the expression of several other genes in Aspergillus nidulans.

The kaeA(KAE1) (suDpro) gene, which was identified in Aspergillus nidulans as a suppressor of proline auxotrophic mutations, encodes the orthologue of Saccharomyces cerevisiae Kae1p, a member of the evolutionarily conserved KEOPS/EKC (Kinase, Endopeptidase and Other Proteins of Small size/Endopeptidase-like and Kinase associated to transcribed Chromatin) complex. In yeast, this complex has been shown to be involved in tRNA modification, transcription, and genome maintenance. In A. nidulans, mutations in kaeA result in several phenotypic effects, the derepression of arginine catabolism genes, and changes in the expression levels of several others, including genes involved in amino acid and siderophore metabolism, sulfate transport, carbon/energy metabolism, translation, and transcription regulation, such as rcoA(TUP1), which encodes the global transcriptional corepressor.

Arginine catabolism in Aspergillus nidulans is regulated by the rrmA gene coding for the RNA-binding protein.

Expression of Aspergillus nidulans arginine catabolism genes, agaA and otaA, is regulated at the level of transcription by a specific induction and two global carbon and nitrogen repression systems. Post-transcriptional and/or post-translational mechanisms have also been proposed to operate additionally. Gene tagging with transposon impala allowed us to select the rrmA gene. RRMA protein contains three conserved RRM domains, typical for RNA-binding proteins. The gene has a complex structure with several potential transcription start sites, an exceptionally long intron in 5'UTR and few uORFs in the intron. RRMA is highly conserved among fungi. Its homologues, Csx1p of Schizosaccharomyces pombe and Ngr1p of Saccharomyces cerevisiae, participate in the post-transcriptional regulation of specific genes by modifying transcript stability. Levels of otaA and agaA transcripts in the rrmA::impala loss of function mutant grown under inducing conditions are significantly higher than in the wild type strain. We propose that RRMA participates in a mechanism promoting agaA and otaA mRNA degradation. The rrmA::impala mutation has pleiotropic character and results in a slow growth phenotype indicating that rrmA functions are not limited to the regulation of arginine catabolism.

L-arginine influences the structure and function of arginase mRNA in Aspergillus nidulans.

Expression of the arginase structural gene (agaA) in Aspergillus nidulans is subject to complex transcriptional and post-transcriptional regulation. Arginase mRNA has a long 5'-UTR sequence. Analysis of this sequence in silico revealed its putative complex secondary structure, the presence of arginine-binding motifs (arginine aptamers) and a short intron with two potential 3' splicing sites. In this report we present evidence that L-arginine (i) binds directly to the arginase 5'-UTR; (ii) invokes drastic changes in the secondary structure of the 5'-UTR, unlike several other L-amino acids and D-arginine; and (iii) forces the selection of one of two 3' splice sites of an intron present in the 5'-UTR. We postulate that expression of the eukaryotic structural gene coding for arginase in A. nidulans is regulated at the level of mRNA stability, depending on riboswitch-mediated alternative splicing of the 5'-UTR intron.

Specific induction and carbon/nitrogen repression of arginine catabolism gene of Aspergillus nidulans--functional in vivo analysis of the otaA promoter.

The arginine catabolism gene otaA encoding ornithine transaminase (OTAse) is specifically induced by arginine and is under the control of the broad-domain carbon and nitrogen repression systems. Arginine induction is mediated by a product of arcA gene coding for Zn(2)C(6) activator. We have identified a region responsible for arginine induction in the otaA promoter (AnUAS(arg)). Deletions within this region result in non-inducibility of OTAse by arginine, whether in an arcA(+) strain or in the presence of the arcA(d)47 gain of function allele. AnUAS(arg) is very similar to the Saccharomyces cerevisiae UAS(arg), a sequence bound by the Zn(2)C(6) activator (ArgRIIp), acting in a complex with two MADS-box proteins (McmIp and ArgRIp). We demonstrate here that two CREA in vitro binding sites in the otaA promoter are functional in vivo. CREA is directly involved in carbon repression of the otaA gene and it also reduces its basal level of expression. Although AREA binds to the otaA promoter in vitro, it probably does not participate in nitrogen metabolite repression of the gene in vivo. We show here that another putative negatively acting GATA factor AREB participates directly or indirectly in otaA nitrogen repression. We also demonstrate that the high levels of OTAse activity are an important factor in the suppression of proline auxotrophic mutations. This suppression can be achieved neither by growing of the proline auxotroph under carbon/nitrogen derepressing conditions nor by introducing of a creA(d) mutation.

Bacterial diversity in Adélie penguin, Pygoscelis adeliae, guano: molecular and morpho-physiological approaches.

The total number of bacteria and culturable bacteria in Adélie penguin (Pygoscelis adeliae) guano was determined during 42 days of decomposition in a location adjacent to the rookery in Admiralty Bay, King George Island, Antarctica. Of the culturable bacteria, 72 randomly selected colonies were described using 49 morpho-physiological tests, 27 of which were subsequently considered significant in characterizing and differentiating the isolates. On the basis of the nucleotide sequence of a fragment of the 16S rRNA gene in each of 72 pure isolates, three major phylogenetic groups were identified, namely the Moraxellaceae/Pseudomonadaceae (29 isolates), the Flavobacteriaceae (14), and the Micrococcaceae (29). Grouping of the isolates on the basis of morpho-physiological tests (whether 49 or 27 parameters) showed similar results to those based on 16S rRNA gene sequences. Clusters were characterized by considerable intra-cluster variation in both 16S rRNA gene sequences and morpho-physiological responses. High diversity in abundance and morphometry of total bacterial communities during penguin guano decomposition was supported by image analysis of epifluorescence micrographs. The results indicate that the bacterial community in penguin guano is not only one of the richest in Antarctica, but is extremely diverse, both phylogenetically and morpho-physiologically.