Extracellular hydrophobic regions in scavenger receptor BI play a key role in mediating HDL-cholesterol transport

The binding of high density lipoprotein (HDL) to scavenger receptor BI (SR-BI) is responsible for whole-body cholesterol disposal via reverse cholesterol transport. The extracellular domain of SR-BI is required for HDL binding and selective uptake of HDL-cholesterol. We identified six highly hydrophobic regions in this domain that may be important for receptor activity and performed site-directed mutagenesis to investigate the importance of these regions in SR-BI-mediated cholesterol transport. Non-conservative mutation of the regions encompassing V67, L140/L142, V164 or V221 reduced hydrophobicity and impaired the ability of SR-BI to bind HDL, mediate selective uptake of HDL-cholesterol, promote cholesterol efflux, and enlarge the cholesterol oxidase-sensitive pool of membrane free cholesterol. In contrast, conservative mutations at V67, V164 or V221 did not affect the hydrophobicity or these cholesterol transport activities. We conclude that the hydrophobicity of N-terminal extracellular regions of SR-BI is critical for cholesterol transport, possibly by mediating receptor-ligand and/or receptor-membrane interactions.     

Transcriptome analysis of germinating maize kernels exposed to smoke-water and the active compound KAR<Subscript>1</Subscript>

Background  

Smoke released from burning vegetation functions as an important environmental signal promoting the germination of many plant species following a fire. It not only promotes the germination of species from fire-prone habitats, but several species from non-fire-prone areas also respond, including some crops. The germination stimulatory activity can largely be attributed to the presence of a highly active butenolide compound, 3-methyl-2H-furo[2,3-c]pyran-2-one (referred to as karrikin 1 or KAR₁), that has previously been isolated from plant-derived smoke. Several hypotheses have arisen regarding the molecular background of smoke and KAR₁ action.     

The concentration dependent biphasic effect of leptin on endogenous cholesterol synthesis in human monocytes

In human monocytes 100 ng/mL leptin increased both statin-inhibitable free radical and cholesterol production in vitro. In our recent study, we aimed to elucidate the concentration dependence of observed leptin-effect. Following leptin stimulation cholesterol synthesis was measured in the presence of inhibitors to determine affected signal pathways. Leptin at low (10-100 ng/mL) concentrations increased [(14)C]acetate incorporation, whereas at 250 ng/mL and higher concentrations it suppressed cholesterol synthesis. HMG CoA reductase, phosphatidyl-3-kinase (PI3K) and mitogen activated protein kinase (MAPK) were involved in mediating leptin effects at low concentrations, whereas the cholesterol synthesis suppression was abolished by inhibitors of protein kinase C (PKC) and PI3K.     

Electromagnetic fields produced by GSM cellular phones and heart rate variability

In this study, 26 healthy young volunteers were submitted to 900 MHz (2 W) GSM cellular phone exposure and to sham exposure in separate sessions. The study was designed to assess cardiac regulatory mechanism in different autonomic nervous system (ANS) states during exposure to low-intensity EMF. Rest-to-stand protocol was applied to evaluate ANS in quiet condition (rest, vagal prevalence) and after a sympathetic activation (stand). The procedure is conducted twice in a double-blind design: once with a genuine EMF exposure and once with a sham exposure (at least 24 h apart). During each session three-leads electrocardiograms were recorded and RR series extracted off-line. Time domain and frequency domain HRV parameters were calculated in every phase of the protocol and during different exposures. The analysis of the data show there was no statistically significant effect due to EMF exposure both on main (i.e., RR mean) and most of the other HRV parameters. A weak interaction between some HRV parameters (i.e., SDNN, TINN, and triangular index in time domain and LF power in frequency domain analysis) and RF exposure was observed and this effect seems to be gathered around the sympathetic response to stand.     

Effect of prototypic drugs ibuprofen and warfarin on global chaotropic unfolding of human serum heme-albumin: a fast-field-cycling 1H-NMR relaxometric study

Human serum albumin (HSA) is the most prominent protein in plasma, but it is also found in tissues and secretions throughout the body. The three-domain design of HSA provides a variety of binding sites for many ligands, including heme and drugs. HSA has been used as a model multidomain protein to investigate how interdomain interactions affect the global folding/unfolding process. Here, we report on the reversible chemical denaturation of heme-HSA involving three different conformational states (F, N, and B, occurring at pH 4.0, 7.0, and 9.0, respectively) and on the effect of prototypic drugs ibuprofen and warfarin on thermodynamics of the reversible unfolding process. Chaotropic unfolding of heme-HSA in the F, N, and B conformations is governed by different thermodynamic regimes, with the B form showing an entropic stabilization of the structure that compensates an enthalpic destabilization, and the F form easily unfolding under entropic control. Warfarin and ibuprofen binding stabilizes heme-HSA in both N and B states.     

The domestication of artichoke and cardoon: from Roman times to the genomic age

BACKGROUND: The history of domestication of artichoke and leafy cardoon is not yet fully understood and when and where it occurred remains unknown. Evidence supports the hypothesis that wild cardoon is the wild progenitor of both these crops. Selection for large, non-spiny heads resulted in artichoke and selection for non-spiny, large stalked tender leaves resulted in leafy cardoon. The two crops differ in their reproductive system: artichoke is mostly vegetatively propagated and perennial, while leafy cardoon is seed propagated and mostly grown as an annual plant. Here, new trends in artichoke cultivation are analysed, while the consequences of these tendencies on the conservation of artichoke genetic resources are highlighted. SCOPE: The historical and artistic records, together with recent literature on genetics and biosystematics, are examined with the aim of achieving a better understanding of the present-day knowledge on the domestication of these two crops. CONCLUSIONS: Historical, linguistic and artistic records are consistent with genetic and biosystematic data and indicate that the domestication of artichoke and cardoon diverged at different times and in different places. Apparently, artichoke was domesticated in Roman times, possibly in Sicily, and spread by the Arabs during early Middle Ages. The cardoon was probably domesticated in the western Mediterranean in a later period.