Lipidic cubic phase serial millisecond crystallography using synchrotron radiation.

Lipidic cubic phases (LCPs) have emerged as successful matrixes for the crystallization of membrane proteins.Moreover, the viscous LCP also provides a highly effective delivery medium for serial femtosecond crystallography (SFX) at X-ray free-electron lasers (XFELs). Here, the adaptation of this technology to perform serial millisecond crystallography (SMX) at more widely available synchrotron microfocus beamlines is described. Compared with conventional microcrystallography, LCP-SMX eliminates the need for difficult handling of individual crystals and allows for data collection at room temperature. The technology is demonstrated by solving a structure of the light-driven protonpump bacteriorhodopsin (bR) at a resolution of 2.4 A ° . The room-temperature structure of bR is very similar to previous cryogenic structures but shows small yet distinct differences in the retinal ligand and proton-transfer pathway

Heart rate variability and target organ damage in hypertensive patients

Background: We evaluated the association between linear standard Heart Rate Variability (HRV) measures and vascular, renal and cardiac target organ damage (TOD). Methods: A retrospective analysis was performed including 200 patients registered in the Regione Campania network (aged 62.4 ± 12, male 64%). HRV analysis was performed by 24-h holter ECG. Renal damage was assessed by estimated glomerular filtration rate (eGFR), vascular damage by carotid intima-media thickness (IMT), and cardiac damage by left ventricular mass index. Results: Significantly lower values of the ratio of low to high frequency power (LF/HF) were found in the patients with moderate or severe eGFR (p-value < 0.001). Similarly, depressed values of indexes of the overall autonomic modulation on heart were found in patients with plaque compared to those with a normal IMT (p-value <0.05). These associations remained significant after adjustment for other factors known to contribute to the development of target organ damage, such as age. Moreover, depressed LF/HF was found also in patients with left ventricular hypertrophy but this association was not significant after adjustment for other factors. Conclusions: Depressed HRV appeared to be associated with vascular and renal TOD, suggesting the involvement of autonomic imbalance in the TOD. However, as the mechanisms by which abnormal autonomic balance may lead to TOD, and, particularly, to renal organ damage are not clearly known, further prospective studies with longitudinal design are needed to determine the association between HRV and the development of TOD

Short-Lived Climate Forcers (Chapter 6)

Short-lived climate forcers (SLCFs) affect climate and are, in most cases, also air pollutants. They include aerosols (sulphate, nitrate, ammonium, carbonaceous aerosols, mineral dust and sea spray), which are also called particulate matter (PM), and chemically reactive gases (methane, ozone, some halogenated compounds, nitrogen oxides, carbon monoxide, non-methane volatile organic compounds, sulphur dioxide and ammonia). Except for methane and some halogenated compounds whose lifetimes are about a decade or more, SLCF abundances are spatially highly heterogeneous since they only persist in the atmosphere from a few hours to a couple of months. SLCFs are either radiatively active or influence the abundances of radiatively active compounds through chemistry (chemical adjustments), and their climate effect occurs predominantly in the first two decades after their emission or formation. They can have either a cooling or warming effect on climate, and they also affect precipitation and other climate variables. Methane and some halogenated compounds are included in climate treaties, unlike the other SLCFs that are nevertheless indirectly affected by climate change mitigation since many of them are often co-emitted with CO2 in combustion processes. This chapter assesses the changes, in the past and in a selection of possible futures, of the emissions and abundances of individual SLCFs primarily on global to continental scales, and how these changes affect the Earth’s energy balance through radiative forcing and feedback in the climate system. The attribution of climate and air-quality changes to emissions sectors and regions, and the effects of SLCF mitigations defined for various environmental purposes, are also assessed

Coherent diffractive imaging of microtubules using an X-ray laser

X-ray free electron lasers (XFELs) create new possibilities for structural studies of biological objects that extend beyond what is possible with synchrotron radiation. Serial femtosecond crystallography has allowed high-resolution structures to be determined from micro-meter sized crystals, whereas single particle coherent X-ray imaging requires development to extend the resolution beyond a few tens of nanometers. Here we describe an intermediate approach: the XFEL imaging of biological assemblies with helical symmetry. We collected X-ray scattering images from samples of microtubules injected across an XFEL beam using a liquid microjet, sorted these images into class averages, merged these data into a diffraction pattern extending to 2 nm resolution, and reconstructed these data into a projection image of the microtubule. Details such as the 4 nm tubulin monomer became visible in this reconstruction. These results illustrate the potential of single-molecule X-ray imaging of biological assembles with helical symmetry at room temperature

Repair of gaps opposite lesions by homologous recombination in mammalian cells

Damages in the DNA template inhibit the progression of replication, which may cause single-stranded gaps. Such situations can be tolerated by translesion DNA synthesis (TLS), or by homology-dependent repair (HDR), which is based on transfer or copying of the missing information from the replicated sister chromatid. Whereas it is well established that TLS plays an important role in DNA damage tolerance in mammalian cells, it is unknown whether HDR operates in this process. Using a newly developed plasmid-based assay that distinguishes between the three mechanisms of DNA damage tolerance, we found that mammalian cells can efficiently utilize HDR to repair DNA gaps opposite an abasic site or benzo[a]pyrene adduct. The majority of these events occurred by a physical strand transfer (homologous recombination repair; HRR), rather than a template switch mechanism. Furthermore, cells deficient in either the human RAD51 recombination protein or NBS1, but not Rad18, exhibited decreased gap repair through HDR, indicating a role for these proteins in DNA damage tolerance. To our knowledge, this is the first direct evidence of gap-lesion repair via HDR in mammalian cells, providing further molecular insight into the potential activity of HDR in overcoming replication obstacles and maintaining genome stability