Evolutionary temperature compensation of carbon fixation in marine phytoplankton

The efficiency of carbon sequestration by the biological pump could decline in the coming decades because respiration tends to increase more with temperature than photosynthesis. Despite these differences in the short-term temperature sensitivities of photosynthesis and respiration, it remains unknown whether the long-term impacts of global warming on metabolic rates of phytoplankton can be modulated by evolutionary adaptation. We found that respiration was consistently more temperature dependent than photosynthesis across 18 diverse marine phytoplankton, resulting in universal declines in the rate of carbon fixation with short-term increases in temperature. Long-term experimental evolution under high temperature reversed the short-term stimulation of metabolic rates, resulting in increased rates of carbon fixation. Our findings suggest that thermal adaptation may therefore have an ameliorating impact on the efficiency of phytoplankton as primary mediators of the biological carbon pump

Comparative experimental evolution reveals species-specific idiosyncrasies in marine phytoplankton adaptation to warming

A number of experimental studies have demonstrated that phytoplankton can display rapid thermal adaptation in response to warmed environments. While these studies provide insight into the evolutionary responses of single species, they tend to employ different experimental techniques. Consequently, our ability to compare the potential for thermal adaptation across different, ecologically relevant, species remains limited. Here, we address this limitation by conducting simultaneous long-term warming experiments with the same experimental design on clonal isolates of three phylogenetically diverse species of marine phytoplankton; the cyanobacterium Synechococcus sp., the prasinophyte Ostreococcus tauri and the diatom Phaeodoactylum tricornutum. Over the same experimental time period, we observed differing levels of thermal adaptation in response to stressful supra-optimal temperatures. Synechococcus sp. displayed the greatest improvement in fitness (i.e., growth rate) and thermal tolerance (i.e., temperature limits of growth). Ostreococcus tauri was able to improve fitness and thermal tolerance, but to a lesser extent. Finally, Phaeodoactylum tricornutum showed no signs of adaptation. These findings could help us understand how the structure of phytoplankton communities may change in response to warming, and possible biogeochemical implications, as some species show relatively more rapid adaptive shifts in their thermal tolerance

Ebola virus VP35 induces high-level production of recombinant TPL-2–ABIN-2–NF-κB1 p105 complex in co-transfected HEK-293 cells

Activation of PKR (double-stranded-RNA-dependent protein kinase) by DNA plasmids decreases translation, and limits the amount of recombinant protein produced by transiently transfected HEK (human embryonic kidney)-293 cells. Co-expression with Ebola virus VP35 (virus protein 35), which blocked plasmid activation of PKR, substantially increased production of recombinant TPL-2 (tumour progression locus 2)–ABIN-2 [A20-binding inhibitor of NF-κB (nuclear factor κB) 2]–NF-κB1 p105 complex. VP35 also increased expression of other co-transfected proteins, suggesting that VP35 could be employed generally to boost recombinant protein production by HEK-293 cells

Evaluation of repeat distal transradial access in the anatomic snuffbox

PurposeThere is increasing interest in the distal radial artery in the anatomic snuffbox as an alternative arterial access point, but the durability of the distal radial artery to support repetitive accesses over multiple procedures is not well established. The purpose of this study was therefore to evaluate success rates for repeated left-sided distal transradial access (ldTRA) in the anatomic snuffbox.MethodsIn this single institution retrospective study, all patients undergoing radioembolization treatments from January 1st, 2019 to May 1st, 2020 were prospectively evaluated for ldTRA. ldTRA was performed by 15 different operators. Exclusion criteria were a left radiocephalic hemodialysis fistula, inability to properly position the arm, Barbeau D waveform, or failed prior ldTRA due to tortuosity. Barbeau patterns, arterial sizes, and success rates at the first, second, and third ldTRA were compared.ResultsFifty patients were evaluated for ldTRA and 44, 39, and 10 underwent one, two, and three ldTRA attempts for a total of 93 procedures. There was no significant change in Barbeau patterns between the first and second (p = 0.13) or first and third (p = 1.0) ldTRA. There was no significant change in artery size between the first (mean, 2.3 mm; range, 1.5–3.4 mm) and second (mean, 2.3 mm; range, 1.6–3.3 mm) (p = 0.59) and first and third (mean, 2.4 mm; range, 1.9–3.3) (p = 0.45) ldTRA. The success rate was not significantly different between the first (93%, 41/44, 95% CI 81%–99%), second (95%, 37/39, 95% CI 83%–99%), and third (100%, 10/10, 95% CI 69%–100%) procedure (p = 1.0). The asymptomatic occlusion rate was 4.1% (2/49, 95% CI 0%–14%), and subsequent ldTRA was successfully completed in both patients with occlusions. There were no hemorrhagic or ischemic complications.ConclusionSuccess rates are indistinguishable among first, second, and third time ldTRA suggesting that this is a durable access point

Characterization of the reversible phosphorylation and activation of ERK8

ERK8 (extracellular-signal-regulated protein kinase 8) expressed in Escherichia coli or insect cells was catalytically active and phosphorylated at both residues of the Thr-Glu-Tyr motif. Dephosphorylation of the threonine residue by PP2A (protein serine/threonine phosphatase 2A) decreased ERK8 activity by over 95% in vitro, whereas complete dephosphorylation of the tyrosine residue by PTP1B (protein tyrosine phosphatase 1B) decreased activity by only 15–20%. Wild-type ERK8 expressed in HEK-293 cells was over 100-fold less active than the enzyme expressed in bacteria or insect cells, but activity could be increased by exposure to hydrogen peroxide, by incubation with the protein serine/threonine phosphatase inhibitor okadaic acid, or more weakly by osmotic shock. In unstimulated cells, ERK8 was monophosphorylated at Tyr-177, and exposure to hydrogen peroxide induced the appearance of ERK8 that was dually phosphorylated at both Thr-175 and Tyr-177. IGF-1 (insulin-like growth factor 1), EGF (epidermal growth factor), PMA or anisomycin had little effect on activity. In HEK-293 cells, phosphorylation of the Thr-Glu-Tyr motif of ERK8 was prevented by Ro 318220, a potent inhibitor of ERK8 in vitro. The catalytically inactive mutants ERK8[D154A] and ERK8[K42A] were not phosphorylated in HEK-293 cells or E. coli, whether or not the cells had been incubated with protein phosphatase inhibitors or exposed to hydrogen peroxide. Our results suggest that the activity of ERK8 in transfected HEK-293 cells depends on the relative rates of ERK8 autophosphorylation and dephosphorylation by one or more members of the PPP family of protein serine/threonine phosphatases. The major residue in myelin basic protein phosphorylated by ERK8 (Ser-126) was distinct from that phosphorylated by ERK2 (Thr-97), demonstrating that, although ERK8 is a proline-directed protein kinase, its specificity is distinct from ERK1/ERK2