alyron, an Insertional Mutation Affecting Early Neural Crest Development in Zebrafish

Abstractalyronz12 (aln) is a recessive lethal mutation that affects early stages of neural crest development in the zebrafish. alyron appears to be an insertional mutation as the mutation was generated following microinjection of plasmid DNA into one-cell embryos and the stably integrated transgenic sequences are closely linked to the mutation. The insertion site harbors multiple copies of the plasmid sequence that have experienced complex rearrangements. Host–insert junction fragments have been molecularly cloned and host sequences adjacent to the transgene have been used to map the mutation to the distal arm of linkage group 15. alyron function is required cell-autonomously in the neural crest lineage. alyron mutants have a severe but not complete deficit of premigratory neural crest as judged by reduced expression of several markers associated with early stages of neural crest development. Lack of premigratory neural crest is likely to account for the two most conspicuous characteristics of alyron mutants: the absence of body pigmentation and the inability to affect blood circulation. The neural crest phenotype of alyron mutants resembles that observed in mouse mutants that lack Pax-3 or both Wnt-1 and Wnt-3a function, and expression of the zebrafish homologues of these genes is greatly reduced in the dorsal neural keels of alyron mutants. In contrast, ventral neural keel identity appears unaffected. Given our findings that the mutation is unlinked to pax or wnt genes that have been described in the zebrafish, we propose that alyron is a novel gene function required for the specification and/or proliferative expansion of neural crest progenitors

Climate geoengineering: issues of path-dependence and socio-technical lock-in

As academic and policy interest in climate geoengineering grows, the potential irreversibility of technological developments in this domain has been raised as a pressing concern. The literature on socio-technical lock-in and path dependence is illuminating in helping to situate current concerns about climate geoengineering and irreversibility in the context of academic understandings of historical socio-technical development and persistence. This literature provides a wealth of material illustrating the pervasiveness of positive feedbacks of various types (from the discursive to the material) leading to complex socio-technical entanglements which may resist change and become inflexible even in the light of evidence of negative impacts. With regard to climate geoengineering, there are concerns that geoengineering technologies might contribute so-called ‘carbon lock-in’, or become irreversibly ‘locked-in’ themselves. In particular, the scale of infrastructures that geoengineering interventions would require, and the issue of the so-called ‘termination effect’ have been discussed in these terms. Despite the emergent and somewhat ill-defined nature of the field, some authors also suggest that the extant framings of geoengineering in academic and policy literatures may already demonstrate features recognizable as forms of cognitive lock-in, likely to have profound implications for future developments in this area. While the concepts of path-dependence and lock-in are the subject of ongoing academic critique, by drawing analytical attention to these pervasive processes of positive feedback and entanglement, this literature is highly relevant to current debates around geoengineering

Treatment patterns and blood counts in patients with polycythemia vera treated with hydroxyurea in the United States: An analysis from the REVEAL study

BACKGROUND: Polycythemia vera (PV) is associated with increased blood cell counts, risk of thrombosis, and symptoms including fatigue and pruritus. National guidelines support the use of hydroxyurea (HU) in high-risk patients or those with some other clinical indication for cytoreduction. PATIENTS AND METHODS: REVEAL is a prospective, observational study designed to collect data pertaining to demographics, disease burden, clinical management, patient-reported outcomes, and health care resource utilization of patients with PV in the United States. In this analysis, HU treatment patterns and outcomes were assessed from 6 months prior to enrollment to the time of discontinuation, death, or data cutoff. RESULTS: Of the 1381 patients who received HU for ≥ 3 months, the median HU exposure was 23.6 months (range, 3.1-38.5 months). The most common maximum daily HU doses were 1000 mg (30.6%) and 500 mg (30.1%); only 6.4% received ≥ 2 g/d HU. Approximately one-third (32.3%) of patients had dose adjustments, 23.8% had dose interruptions, and 257 (18.6%) discontinued HU. The most common reasons for HU discontinuations and interruptions were adverse events/intolerance (37.1% and 54.5%, respectively) and lack of efficacy (35.5% and 22.1%, respectively). Of those who received HU for ≥ 3 months, 57.1% had hematocrit values \u3e 45% on ≥ 1 occasion, 33.1% continued to receive phlebotomies, and 27.4% had uncontrolled myeloproliferation. CONCLUSION: The results of this analysis emphasize the need for active management of patients with PV with appropriate HU dose titration to maintain blood count control while monitoring for signs and symptoms of HU intolerance

Nuclear pore component Nup98 is a potential tumor suppressor and regulates posttranscriptional expression of select p53 target genes

The p53 tumor suppressor utilizes multiple mechanisms to selectively regulate its myriad target genes, which in turn mediate diverse cellular processes. Here, using conventional and single-molecule mRNA analyses, we demonstrate that the nucleoporin Nup98 is required for full expression of p21, a key effector of the p53 pathway, but not several other p53 target genes. Nup98 regulates p21 mRNA levels by a posttranscriptional mechanism in which a complex containing Nup98 and the p21 mRNA 3\u27UTR protects p21 mRNA from degradation by the exosome. An in silico approach revealed another p53 target (14-3-3sigma) to be similarly regulated by Nup98. The expression of Nup98 is reduced in murine and human hepatocellular carcinomas (HCCs) and correlates with p21 expression in HCC patients. Our study elucidates a previously unrecognized function of wild-type Nup98 in regulating select p53 target genes that is distinct from the well-characterized oncogenic properties of Nup98 fusion proteins

The 4D Nucleome Project [preprint]

The spatial organization of the genome and its dynamics contribute to gene expression and cellular function in normal development as well as in disease. Although we are increasingly well equipped to determine a genome\u27s sequence and linear chromatin composition, studying the three-dimensional organization of the genome with high spatial and temporal resolution remains challenging. The 4D Nucleome Network aims to develop and apply approaches to map the structure and dynamics of the human and mouse genomes in space and time with the long term goal of gaining deeper mechanistic understanding of how the nucleus is organized. The project will develop and benchmark experimental and computational approaches for measuring genome conformation and nuclear organization, and investigate how these contribute to gene regulation and other genome functions. Further efforts will be directed at applying validated experimental approaches combined with biophysical modeling to generate integrated maps and quantitative models of spatial genome organization in different biological states, both in cell populations and in single cells