| 1. |
- Soderberg, A. M., et al.
(författare)
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Discovery of a Relativistic Supernova Without a Gamma-ray Trigger
- 2009
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Annan publikation (populärvet., debatt m.m.)abstract
- Type Ibc supernovae (SNe Ibc) mark the gravitational collapse of some massive stars (M > 20 Msun) propelling several solar masses of material to typical velocities of ~10,000 km/s. The closely-related but exceedingly rare class of long-duration gamma-ray bursts (GRBs) produce, in addition, a relativistic outflow powered by a central engine (accreting black hole or neutron star) and have been found exclusively through their gamma-ray signal. Here we report the discovery of luminous radio emission from the seemingly ordinary Type Ibc SN 2009bb which outshines that of all other SNe Ibc observed on a comparable timescale. These observations require a substantial mildly-relativistic outflow and indicate that the explosion was powered by a central engine, thus representing the first such event discovered without the aid of a gamma-ray trigger. A comparison with our extensive radio survey of SNe Ibc reveals that the fraction of such events is low (roughly 1 percent), measured independently from, and yet consistent with, the inferred rate of nearby GRBs. This discovery marks the observational realization that long-wavelength surveys will soon rival gamma-ray satellites in pinpointing nearby engine-driven explosions.
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| 2. |
- Cockerill, Christopher Alan, 1994-, et al.
(författare)
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That’s so Last Season: Unraveling the Genomic Cost of fur farming in Arctic Foxes
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Humans have relied on animal fur for thousands of years, yet fur farming only began relatively recently during the mid-19th Century. Little is known of this incipient domestication process or the genomic consequences involved. It is hypothesized that domestication involves processes such as founder effects, population bottlenecks and low population size, which, when combined with intense artificial selection, lead to inbreeding, a limited genepool and reduced fitness. The arctic fox (Vulpes lagopus) is one such species that has been farmed intensively since the early 1900s and has been artificially selected for economic phenotypes. We investigated the origin of these lineages and the genomic consequences of intense farming by comparing the genomes of farmed and wild arctic foxes from across their range. Our research reveals signatures of recent inbreeding through long Runs of Homozygosity (ROH) and reduced genomic variation in Fennoscandian farm foxes relative to the wild Fennoscandian population. We identified a coastal ecotype origin for all farmed arctic foxes, as opposed to the other main, inland, lemming ecotype, placing them phylogenetically close to the wild Icelandic population. The depleted genome-wide heterozygosity and increased recent inbreeding in farm fox lineages is consistent with a heavy cost of domestication, shedding light on the demographic history and genomic consequences of human manipulation. We highlight the need for increased genomic investigations into fur farm populations to understand the incipient domestication process and uncover the cost of intense farming. The genomic consequences of domestication must be considered in the management of fur farm populations, with actionable steps needed to prevent descendants of escaped farm foxes from polluting the gene pool in the wild through introgression.
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| 3. |
- Malm, Magdalena, 1983-, et al.
(författare)
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Harnessing secretory pathway differences between HEK293 and CHO to rescue production of difficult to express proteins
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Biologics represent the fastest growing group of therapeutics, but many advanced recombinant protein moieties remain difficult to produce. Here, we identify bottlenecks limiting expression of recombinant human proteins through a systems biology analysis of the transcriptomes of CHO and HEK293 during recombinant overexpression. Surprisingly, one third of the challenging human proteins displayed improved secretion upon host cell swapping from CHO to HEK293. While most components of the secretory machinery showed comparable expression levels in both expression hosts, genes with significant expression variation were identified. Among these, ATF4, SRP9, JUN, PDIA3 and HSPA8 were validated as productivity boosters in CHO. Further, more heavily glycosylated products benefitted more from the elevated activities of the N- and O-glycosyltransferases found in HEK293. Collectively, our results demonstrate the utilization of HEK293 for expression rescue of human proteins and suggest a methodology for identification of secretory pathway components improving recombinant protein yield in HEK293 and CHO.
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