instruction:
Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.
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Context: The endosteum of the bone marrow provides a specialized hypoxic niche that may serve to preserve the integrity, pluripotency, longevity and stemness of resident mesenchymal stem cells (MSCs). To explore the molecular genetic consequences of such a niche we subjected human (h) MSCs to a pO2 of 4 mmHg and analyzed global gene expression and alternative splicing (AS) by genome-exon microarray and RT-qPCR, and phenotype by western blot and immunostaining.', 'Out of 446 genes differentially regulated by >2.5-fold, down-regulated genes outnumbered up-regulated genes by 243:203. Exon analyses revealed 60 hypoxia-regulated AS events with splice indices (SI) >1.0 from 53 genes and a correlation between high SI and degree of transcript regulation. Parallel analyses of a publicly available AS study on human umbilical vein endothelial cells (HUVECs) showed that there was a strong cell-specific component with only 11 genes commonly regulated in hMSCs and HUVECs and 17 common differentially spliced genes. Only 3 genes were differentially responsive to hypoxia at the gene (>2.0) and AS levels in both cell types. Functional assignments revealed unique profiles of gene expression with complex regulation of differentiation, extracellular matrix, intermediate filament and metabolic marker genes. Antioxidant genes, striated muscle genes and insulin/IGF-1 signaling intermediates were down-regulated. There was a coordinate induction of 9 out of 12 acidic keratins that along with other epithelial and cell adhesion markers implies a partial mesenchymal to epithelial transition.
Answer: We conclude that severe hypoxia confers a quiescent phenotype in hMSCs that is reflected by both the transcriptome profile and gene-specific changes of splicosome actions. The results reveal that severe hypoxia imposes markedly different patterns of gene regulation of MSCs compared with more moderate hypoxia. This is the first study to report hypoxia-regulation of AS in stem/progenitor cells and the first molecular genetic characterization of MSC in a hypoxia-induced quiescent immobile state.
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Does severe hypoxia exert parallel and cell-specific regulation of gene expression and alternative splicing in human mesenchymal stem cells?


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Context: Invasive species can have devastating effects on native ecosystems and therefore impose a significant threat to human welfare. The introduction rate of invasive species has accelerated dramatically in recent times due to human activity (anthropogenic effects), with a steadily growing pool of widespread tramp species. We present an in-depth analysis of four pantropical species of Xyleborus ambrosia beetles (Xyleborus volvulus, Xyleborus perforans, Xyleborus ferrugineus, and Xyleborus affinis) with similar ecology (fungus cultivation in dead wood), reproductive biology (permanent inbreeding) and genetic system (haplodiploidy). The unique combination of reproductive traits and broad host plant usage pre-adapts these beetles for colonizing of new areas.', 'We found that all four species were broadly distributed long before human-assisted dispersal became common, and that the impact of anthropogenic effects varied among the species. For X. volvulus, X. perforans, and X. affinis there was evidence of ancient establishment in numerous regions, but also of abundant recent introductions into previously colonized areas. For X. ferrugineus, we found clear biogeographical structuring of old clades, but little evidence for recent successful introductions.
Answer: Our results indicate that current human-aided transoceanic dispersal has strongly affected the genetic makeup of three of the species in this study. However, current biogeographical patterns of all four species are equally, if not more strongly, influenced by ancient establishment on different continents.
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Do globally distributed Xyleborus species reveal recurrent intercontinental dispersal in a landscape of ancient worldwide distributions?


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Context: We aim to find what is the relationship between B cell antibody responses and specific T cell help in the specific cases of allergy and tolerance to peanuts.', 'B cell antibody responses to foreign proteins usually depend upon antigen-specific T cell help. However, specific antibody levels can sometimes be maintained lifelong after infections or vaccination.', 'We measured peanut-specific proliferation and antibody levels in peanut-allergic and non-allergic children using tritiated thymidine incorporation and UniCAP, respectively. We also investigated the corresponding tetanus toxoid specific responses in both groups.', "We found that tetanus-specific IgG did not correlate with lymphocyte proliferation (Spearman rank correlation coefficient r'=0.08, P=0.74) nor with tetanus-specific cytokine production (IFN-gamma: r'=0.198, P=0.285; TNF-alpha: r'=0.274, P=0.146; IL-4: r'=-0.007, P=0.96; P=0.221; IL-13: r'=0.363, P=0.056). Conversely, in peanut-allergic donors, peanut-specific IgE (average 21 kU/L, median 2.27 kU/L, range 0.34-100 kU/L) but not peanut-specific IgG was positively correlated with proliferation (r'=0.751, P=0.003). In these donors, specific IgE was positively correlated with peanut-specific Th2 cytokines production: r'=0.635, P=0.02 for IL-4 and r'=0.641, P=0.025 for IL-13 and negatively correlated with Th1 cytokines (r'=-0.71, P=0.007 for IFN-gamma and r'=-0.746, P=0.005 for TNF-alpha, respectively). However, peanut-specific IgE was not correlated with T cell proliferation or cytokine production in non-allergic individuals. In conclusion, in allergic individuals, B and T cell responses to peanut antigens are correlated whereas normal immune responses B and T cell responses are uncoupled.
Answer: Our results support the view that B cell responses to allergens but not those to non-allergenic proteins are correlated with specific T cell responses and therefore specific immunotherapy targeting of such T cells would inhibit allergen-specific B cells.
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Are peanut-specific B and T cell responses correlated in peanut-allergic but not in non-allergic individuals?