Characterization of a Brassica napus myrosinase pseudogene: myrosinases are members of the BGA family of β-glycosidases

Myrosinase isoenzymes are known to be encoded by two different families of genes denoted MA and MB. Nucleotide sequence analysis of a Brassica napus genomic clone containing a gene for myrosinase revealed it to be a pseudogene of the MA family. The gene spans more than 5 kb and contains at least 12 exons. The exon sequence of the gene is highly similar to myrosinase cDNA sequences. However, the gene displays three potential or actual pseudogene characters. Southern blot analysis using probes from the 3 portions of the genomic and B. napus MA and MB cDNA clones showed that MA type myrosinases are encoded by approximately 4 genes, while MB type myrosinases are encoded by more than 10 genes in B. napus. Northern blots with mRNA from seeds and young leaves probed with the MA-and MB-specific probes showed that the MA and MB myrosinase gene families are differentially expressed. Myrosinases are highly similar to proteins of a -glycosidase enzyme family comprising both -glycosidases and phospho--glycosidases of as diverged species as archaebacteria, bacteria, mammals and plants. By homology to these -glycosidases, putative active site residues in myrosinase are discussed on the basis of the similarity between -glycosidases and cellulases.     

Effectiveness of a WHO self‐help psychological intervention for preventing mental disorders among Syrian refugees in Turkey: a randomized controlled trial

Refugees are at high risk of developing mental disorders. There is no evidence from randomized controlled trials (RCTs) that psychological interventions can prevent the onset of mental disorders in this group. We assessed the effectiveness of a self‐help psychological intervention developed by the World Health Organization, called Self‐Help Plus, in preventing the development of mental disorders among Syrian refugees experiencing psychological distress in Turkey. A two‐arm, assessor‐masked RCT was conducted in two Turkish areas. Eligible participants were adult Syrian refugees experiencing psychological distress (General Health Questionnaire ≥3), but without a diagnosis of mental disorder. They were randomly assigned either to the Self‐Help Plus arm (consisting of Self‐Help Plus combined with Enhanced Care as Usual, ECAU) or to ECAU only in a 1:1 ratio. Self‐Help Plus was delivered in a group format by two facilitators over five sessions. The primary outcome measure was the presence of any mental disorder assessed by the Mini International Neuropsychiatric Interview at six‐month follow‐up. Secondary outcome measures were the presence of mental disorders at post‐intervention, and psychological distress, symptoms of post‐traumatic stress disorder and depression, personally identified psychological outcomes, functional impairment, subjective well‐being, and quality of life at post‐intervention and six‐month follow‐up. Between October 1, 2018 and November 30, 2019, 1,186 refugees were assessed for inclusion. Five hundred forty‐four people were ineligible, and 642 participants were enrolled and randomly assigned to either Self‐Help Plus (N=322) or ECAU (N=320). Self‐Help Plus participants were significantly less likely to have any mental disorders at six‐month follow‐up compared to the ECAU group (21.69% vs. 40.73%; Cramer''s V = 0.205, p<0.001, risk ratio: 0.533, 95% CI: 0.408‐0.696). Analysis of secondary outcomes suggested that Self‐Help Plus was not effective immediately post‐intervention, but was associated with beneficial effects at six‐month follow‐up in terms of symptoms of depression, personally identified psychological outcomes, and quality of life. This is the first prevention RCT ever conducted among refugees experiencing psychological distress but without a mental disorder. Self‐Help Plus was found to be an effective strategy for preventing the onset of mental disorders. Based on these findings, this low‐intensity self‐help psychological intervention could be scaled up as a public health strategy to prevent mental disorders in refugee populations exposed to ongoing adversities.     

Hypervariable and Highly Divergent Intron–Exon Organizations in the Chordate Oikopleura dioica

Oikopleura dioica is a pelagic tunicate with a very small genome and a very short life cycle. In order to investigate the intron–exon organizations in Oikopleura, we have isolated and characterized ribosomal protein EF-1, Hox, and -tubulin genes. Their intron positions have been compared with those of the same genes from various invertebrates and vertebrates, including four species with entirely sequenced genomes. Oikopleura genes, like Caenorhabditis genes, have introns at a large number of nonconserved positions, which must originate from late insertions or intron sliding of ancient insertions. Both species exhibit hypervariable intron–exon organization within their -tubulin gene family. This is due to localization of most nonconserved intron positions in single members of this gene family. The hypervariability and divergence of intron positions in Oikopleura and Caenorhabditis may be related to the predominance of short introns, the processing of which is not very dependent upon the exonic environment compared to large introns. Also, both species have an undermethylated genome, and the control of methylation-induced point mutations imposes a control on exon size, at least in vertebrate genes. That introns placed at such variable positions in Oikopleura or C. elegans may serve a specific purpose is not easy to infer from our current knowledge and hypotheses on intron functions. We propose that new introns are retained in species with very short life cycles, because illegitimate exchanges including gene conversion are repressed. We also speculate that introns placed at gene-specific positions may contribute to suppressing these exchanges and thereby favor their own persistence.Supplementary material () is available for this article.     

Variations in transfection efficiency of VEGF165 and VEGF121-cDNA

Little is known about the expression pattern of vascular endothelial growth factor (VEGF) among smooth muscle cells of different arterial regions. Therefore, we have conducted studies aimed at increasing expression of VEGF in cultured human smooth muscle cells (SMCs) from different sites: aorta, umbilical artery, and coronary artery. Two plasmids harboring human VEGF₁₂₁ and VEGF₁₆₅ isoforms, respectively, were constructed and lipotransfected into vascular SMCs, using the Fu-GENE 6. Extensive optimization of transfection conditions were performed prior to this. Different basal levels of VEGF were observed between cell types: from 0.51–0.95 pg/mL/μg protein in umbilical artery, through 2.32–2.39 pg/mL/μg protein in coronary artery, to 5.45–7.52 pg/mL/μg protein in aortic SMCs. Significant differences in responses to transfection were also observed: The increase in VEGF production was most pronounced in umbilical artery SMCs (e.g., with 4 μg VEGF₁₂₁-cDNA/in the wells)—an approximate 600-fold as opposed to an 18-fold increase in aortic SMCs and a 29-fold increase in coronary artery SMCs. In addition, we observed significant increases in proliferation rate of aortic and coronary endothelial cells (ECs), after incubation with conditioned medium from VEGF-transfected SMCs. Observed changes differed in relation to cell origin and isoform.     

Bayesian population dynamics of interacting species: great gerbils and fleas in Kazakhstan

We propose a discrete-time Bayesian hierarchical model for the population dynamics of the great gerbil-flea ecological system. The model accounts for the sampling variability arising from data originally collected for other purposes. The prior for the unknown population densities incorporates specific biological hypotheses regarding the interacting dynamics of the two species, as well as their life cycles, where density-dependent effects are included. Posterior estimates are obtained via Markov chain Monte Carlo. The variance of the observed density estimates is a quadratic function of the unknown density. Our study indicates the presence of a density-dependent growth rate for the gerbil population. For the flea population there is clear evidence of density-dependent over-summer net growth, which is dependent on the flea-to-gerbil ratio at the beginning of the reproductive summer. Over-winter net growth is favored by high density. We estimate that on average 35% of the gerbil population survives the winter. Our study shows that hierarchical Bayesian models can be useful in extracting ecobiological information from observational data.     

The Werner syndrome helicase and exonuclease cooperate to resolve telomeric D loops in a manner regulated by TRF1 and TRF2

Werner syndrome (WS) is characterized by features of premature aging and is caused by loss of the RecQ helicase protein WRN. WS fibroblasts display defects associated with telomere dysfunction, including accelerated telomere erosion and premature senescence. In yeast, RecQ helicases act in an alternative pathway for telomere lengthening (ALT) via homologous recombination. We found that WRN associates with telomeres when dissociation of telomeric D loops is likely during replication and recombination. In human ALT cells, WRN associates directly with telomeric DNA. The majority of TRF1/PCNA colocalizing foci contained WRN in live S phase ALT cells but not in telomerase-positive HeLa cells. Biochemically, the WRN helicase and 3' to 5' exonuclease act simultaneously and cooperate to release the 3' invading tail from a telomeric D loop in vitro. The telomere binding proteins TRF1 and TRF2 limit digestion by WRN. We propose roles for WRN in dissociating telomeric structures in telomerase-deficient cells.