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Background:Telomere-binding proteins stabilize chromosomes and regulate telomerase elongation. Results: Rap1 binds partially single-stranded DNA and influences binding of Cdc13 to 3Ј overhangs. Conclusion: Rap1 and Cdc13 provide protection of the respective 3Ј-and 5Ј-ends and compete for binding at telomere ds-ss junctions. Significance: Knowledge of the telomeric DNA-protein interactions is crucial for understanding the molecular mechanisms of the telomerase extension.

BackgroundTelomeres are protective cap structures at the ends of the linear eukaryotic chromosomes, which provide stability to the genome by shielding from degradation and chromosome fusions. The cap consists of telomere-specific proteins binding to the respective single- and double-stranded parts of the telomeric sequence. In addition to the nucleation of the chromatin structure the telomere-binding proteins are involved in the regulation of the telomere length. However, the telomeric sequences are highly diverged among yeast species. During the evolution this high rate of divergency presents a challenge for the sequence recognition of the telomere-binding proteins.ResultsWe found that the Saccharomyces castellii protein Rap1, a negative regulator of telomere length, binds a 12-mer minimal binding site (MBS) within the double-stranded telomeric DNA. The sequence specificity is dependent on the interaction with two 5 nucleotide motifs, having a 6 nucleotide centre-to-centre spacing. The isolated DNA-binding domain binds the same MBS and retains the same motif binding characteristics as the full-length Rap1 protein. However, it shows some deviations in the degree of sequence-specific dependence in some nucleotide positions. Intriguingly, the positions of most importance for the sequence-specific binding of the full-length Rap1 protein coincide with 3 of the 4 nucleotides utilized by the 3' overhang binding protein Cdc13. These nucleotides are very well conserved within the otherwise highly divergent telomeric sequences of yeasts.ConclusionsRap1 and Cdc13 are two very distinct types of DNA-binding proteins with highly separate functions. They interact with the double-stranded vs. the single-stranded telomeric DNA via significantly different types of DNA-binding domain structures. However, we show that they are dependent on coinciding nucleotide positions for their sequence-specific binding to telomeric sequences. Thus, we conclude that during the molecular evolution they act together to preserve a core sequence of the telomeric DNA.

Background: Nicaraguans have migrated internally and internationally for centuries due to economic, political and sociocultural factors. Deficiencies in the country’s health care system have produced inequities in people’s access to health care and medicines. Remittances have become an important source of income, partly invested in health.Objectives: The overall aim of the study was to analyse migration–health relations in contemporary Nicaragua within a broader context of socio-economic transformations.Methods: The study uses a mixed-methods approach, combining qualitative interview data and quantitative survey data.Results: The findings show that migration is commonly practised as a strategy for making a living and is related to the struggle for a better life. Health concerns are indirectly embedded in people’s mobile livelihoods, but also directly influence migration motives. Furthermore, migration involves both advantages and disadvantages for health. Physical and sexual violence can come to an end for migrating women, health care and medicine can become more accessible for internal migrants, and vulnerabilities caused by environmental disasters can be avoided by moving. Moreover, remittances can improve people’s everyday life and health. Yet migration can also be a stressful and health-damaging event. International migrants, particularly the undocumented, can have problems accessing health care, and also experience much danger at border crossings. Transnational families can suffer emotionally as well as physically due to separation. Findings from the survey show that family members of migrants do not rate their physical health as good as often as non-migrating families.Conclusions: The Nicaraguan population is not guaranteed its social rights of citizenship. This results in mobile livelihoods and the need for translocal social support (e.g. remittances). Migration can have both positive and negative effects on health for migrants and their family members; geographical distance and social differences are key to the outcome.

BackgroundThe changing climate and the desire to use renewable oil sources necessitate the development of new oilseed crops. Field cress (Lepidium campestre) is a species in the Brassicaceae family that has been targeted for domestication not only as an oilseed crop that produces seeds with a desirable industrial oil quality but also as a cover/catch crop that provides valuable ecosystem services. Lepidium is closely related to Arabidopsis and display significant proportions of syntenic regions in their genomes. Arabidopsis genes are among the most characterized genes in the plant kingdom and, hence, comparative genomics of Lepidium-Arabidopsis would facilitate the identification of Lepidium candidate genes regulating various desirable traits.ResultsHomologues of 30 genes known to regulate vernalization, flowering time, pod shattering, oil content and quality in Arabidopsis were identified and partially characterized in Lepidium. Alignments of sequences representing field cress and two of its closely related perennial relatives: L. heterophyllum and L. hirtum revealed 243 polymorphic sites across the partial sequences of the 30 genes, of which 95 were within the predicted coding regions and 40 led to a change in amino acids of the target proteins. Within field cress, 34 polymorphic sites including nine non-synonymous substitutions were identified. The phylogenetic analysis of the data revealed that field cress is more closely related to L. heterophyllum than to L. hirtum.ConclusionsThere is significant variation within and among Lepidium species within partial sequences of the 30 genes known to regulate traits targeted in the present study. The variation within these genes are potentially useful to speed-up the process of domesticating field cress as future oil crop. The phylogenetic relationship between the Lepidium species revealed in this study does not only shed some light on Lepidium genome evolution but also provides important information to develop efficient schemes for interspecific hybridization between different Lepidium species as part of the domestication efforts.Electronic supplementary materialThe online version of this article (10.1186/s12863-018-0624-9) contains supplementary material, which is available to authorized users.