Emergence success

Each row represents a group of papae from the same clutch of eggs laid at the same day by a group of females fed on the same host individua

Pupation success

Each row represents a clutch of eggs laid at the same day by a group of females fed on the same host individua

Data from: Use it or lose it: reproductive implications of ecological specialization in a haematophagous ectoparasite

Using experimentally induced disruptive selection, we tested two hypotheses regarding the evolution of specialization in parasites. The ‘trade-off’ hypothesis suggests that adaptation to a specific host may come at the expense of a reduced performance when exploiting another host. The alternative ‘relaxed selection’ hypothesis suggests that the ability to exploit a given host would deteriorate when becoming obsolete. Three replicate populations of a flea Xenopsylla ramesis were maintained on each of two rodent hosts, Meriones crassus and Dipodillus dasyurus, for nine generations. Fleas maintained on a specific host species for a few generations substantially decreased their reproductive performance when transferred to an alternative host species, whereas they generally did not increase their performance on their maintenance host. The results support the ‘relaxed selection’ hypothesis of the evolution of ecological specialization in haematophagous ectoparasites, while suggesting that trade-offs are unlikely drivers of specialization. Further work is needed to study the extent by which the observed specializations are based on epigenetic or genetic modifications

Egg production

Each row represents eggs laid by a group of fleas fed simultaneously on the same host

Acetylene Reactivity on Pd-Cu Nanoparticles Supported on Thin Silica Films: The Role of the Underlying Substrate

Heterogeneous chemistry that develops on ultra-thin films such as bilayer SiO2/Ru(0001) is interesting as a model catalysis system. We have studied the partial decomposition and hydrogenation of acetylene to ethylene and its trimerization to benzene on Pd-Cu bimetallic alloy nano-particles (NPs) supported on those thin silica films. In comparing the bilayer SiO2/Ru(0001) to thicker silica layers without metallic substrate, e.g., the native SiO2/Si(001), the size distribution of the clusters is narrower on the bilayer SiO2/Ru(0001) substrate, demonstrating the effect of the underlying metal in preventing cluster diffusion during their growth. In addition, the effect of medium pressure on NP shape has been investigated via transmission electron microscopy (TEM) imaging of the NPs on relatively thick SiO2. The NPs become elongated when exposed to 0.2 mbar acetylene inside a moderate-pressure cell embedded within an ultra-high vacuum (UHV) chamber. By changing the elemental composition of the NPs on both substrates, the important effect of the sub-oxide material on catalyst reaction selectivity has been emonstrated. However, the effect of the composition of the bare NPs is not enough to actually define the long-term activity of a catalyst. In order to address more realistic conditions, we performed consecutive reactivity cycles by adsorbing acetylene at 110K with subsequent annealing up to 400K in UHV on the same 1Pd:1Cu NPs/bilayer SiO2/Ru(0001) catalyst. This revealed a strong decrease in the selectivity towards ethylene, from an ethylene/benzene product yield ratio of 370±150 in the first cycle down to 50±15 during the third to fifth cycles. Carbon atoms accumulation on the metallic particles in the first and subsequent runs is the main reason for this modification in selectivity. Consecutive reactivity study uniquely demonstrates how rapidly and significantly the catalyst’s performance is modified during the initial stages of its heterogeneous catalytic reactivity

High-dose rifamycins in the treatment of TB: a systematic review and meta-analysis

BackgroundThere is growing interest in using high-dose rifamycin (HDR) regimens in TB treatment, but the safety and efficacy of HDR regimens remain uncertain. We performed a systematic review and meta-analysis comparing HDR to standard-dose rifamycin (SDR) regimens.MethodsWe searched MEDLINE, Embase, CENTRAL, Cochrane Database of Systematic Reviews and clinicaltrials.gov for prospective studies comparing daily therapy with HDRs to SDRs. Rifamycins included rifampicin, rifapentine and rifabutin. Our primary outcome was the rate of severe adverse events (SAEs), with secondary outcomes of death, all adverse events, SAE by organ and efficacy outcomes of 2-month culture conversion and relapse. This study was prospectively registered in the International Prospective Register of Systematic Reviews (CRD42020142519).ResultsWe identified 9057 articles and included 13 studies with 6168 participants contributing 7930 person-years (PY) of follow-up (HDR: 3535 participants, 4387 PY; SDR: 2633 participants, 3543 PY). We found no significant difference in the pooled incidence rate ratio (IRR) of SAE between HDR and SDR (IRR 1.00, 95% CI 0.82 to 1.23,I2=41%). There was no significant difference when analysis was limited to SAE possibly, probably or likely medication-related (IRR 1.07, 95% CI 0.82 to 1.41,I2=0%); studies with low risk of bias (IRR 0.98, 95% CI 0.79 to 1.20,I2=44%); or studies using rifampicin (IRR 1.00, 95% CI 0. 0.75–1.32,I2=38%). No significant differences were noted in pooled outcomes of death, 2-month culture conversion and relapse.ConclusionsHDRs were not associated with a significant difference in SAEs, 2-month culture conversion or death. Further studies are required to identify specific groups who may benefit from HDR.</jats:sec