Association between a rare novel TP53 variant (rs78378222) and melanoma,squamous cell carcinoma of head and neck and lung cancer susceptibility in non‐Hispanic Whites

Recently, several studies have investigated the association between a newly reported rare functional single nucleotide polymorphism (SNP) in TP53 (rs78378222) and cancer risk, but generated inconsistent findings. The present study further investigated this association with risk of melanoma, squamous cell carcinoma of head and neck (SCCHN) and lung cancer. Using volunteers of non‐Hispanic Whites recruited for three large case–control studies, we genotyped the TP53 rs78378222 SNP in 1329 patients with melanoma, 1096 with SCCHN, 1013 with lung cancer and 3000 cancer‐free controls. Overall, we did not observe any variant homozygotes in this study population, nor significant associations between the TP53 rs78378222AC genotype or C allele and risk for melanoma (P = 0.680 and 0.682 respectively) and lung cancer (P = 0.379 and 0.382 respectively), but a protection against SCCHN (P = 0.008 and 0.008 respectively), compared with the AA genotype or A allele. An additional meta‐analysis including 19,423 cancer patients and 54,050 controls did not support such a risk association either. Our studies did not provide statistical evidence of an association between this rare TP53 variant and increased risk of melanoma, nor of lung cancer, but a possible protection against SCCHN.     

Tagging of Escherichia coli proteins with new cassettes allowing in vivo systematic fluorescent and luminescent detection,and purification from physiological expression levels

We designed cassettes allowing the systematic fusion of fluorescent or luminescent proteins preceded by the calmodulin binding peptide tag to the C–terminus of Escherichia coli proteins. The chromosomal insertion, and thus physiological expression level of these fusions, permits the study of protein localization by fluorescent microscopy and protein quantification, in vivo and dynamically in diverse conditions. Furthermore, the calmodulin binding peptide tag allows standard detection, affinity purification, and co–purification experiments. These cassettes are therefore very valuable for the versatility of experiments they make available for a given strain, from biochemistry to dynamic and in vivo studies.     

Reevaluation of the electrophoretic migration behavior of soluble globular proteins in the native and detergent-denatured states in polyacrylamide gels

Although sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis is widely used for estimating molecular masses of proteins, considerable uncertainty still exists both about the structure of SDS-protein complexes and about their mechanism of electrophoretic migration. In this study, soluble globular proteins, with masses of 14-200 kDa, were heat-denatured in the presence of SDS and their relative total molecular volume and net charge were estimated from Ferguson plots of electrophoretic mobility vs acrylamide concentration. Native globular protein served as standards for overall molecular size and effective radii. Results revealed at least two independent electrophoretic migration mechanisms for the SDS-protein complexes: (i) for proteins in the 14-65 kDa range at <15% acrylamide, linear Ferguson plots suggested that they migrated ideally and that their effective radii could be estimated in this manner: (ii) concave plots at higher gel concentrations, and for complexes derived from larger proteins, indicated that migration in these cases could be described by reptation theory. Migration of the large proteins at lower gel concentrations and small proteins at higher gel concentrations was not well described by either theory, representing intermediate behavior not described by these mechanisms. These data support models in which all but the smallest SDS-protein complexes adopt a necklace-like structure in which spherical micelles are distributed along the unfolded polypeptide chain. Possible relations to recent alternative models of gel electrophoresis are also discussed.     

Lateral organization of biological membranes

The lateral organization of biological membranes is of great importance in many biological processes, both for the formation of specific structures such as super-complexes and for function as observed in signal transduction systems. Over the last years, AFM studies, particularly of bacterial photosynthetic membranes, have revealed that certain proteins are able to segregate into functional domains with a specific organization. Furthermore, the extended non-random nature of the organization has been suggested to be important for the energy and redox transport properties of these specialized membranes. In the work reported here, using a coarse-grained Monte Carlo approach, we have investigated the nature of interaction potentials able to drive the formation and segregation of specialized membrane domains from the rest of the membrane and furthermore how the internal organization of the segregated domains can be modulated by the interaction potentials. These simulations show that long-range interactions are necessary to allow formation of membrane domains of realistic structure. We suggest that such possibly non-specific interactions may be of great importance in the lateral organization of biological membranes in general and in photosynthetic systems in particular. Finally, we consider the possible molecular origins of such interactions and suggest a fundamental role for lipid-mediated interactions in driving the formation of specialized photosynthetic membrane domains. We call these lipid-mediated interactions a ‘lipophobic effect.’     

Inside Cover: Generalized spectral light scatter models of diverse bacterial colony morphologies (J. Biophotonics 12/2019)

The forward elastic‐light‐scattering pattern of a bacterial colony reflects its morphological characteristics. Three bacteria genera whose colonies having convex, crateriform, or irregular elevation were investigated to study the correlation between the morphology and the scattering pattern of the colony. The difference in the colony elevation produced distinct shapes of light diffraction in the scattering pattern, resulting circular diffraction rings or scattered light. Further details can be found in the article by Iyll‐Joon Doh, Jennifer Sturgis, Diana V. Sarria Zuniga, et al. ( e201900149 ).

     

Salicylic acid-independent plant defence pathways

Salicylic acid is an important signalling molecule involved in both locally and systemically induced disease resistance responses. Recent advances in our understanding of plant defence signalling have revealed that plants employ a network of signal transduction pathways, some of which are independent of salicylic acid. Evidence is emerging that jasmonic acid and ethylene play key roles in these salicylic acid-independent pathways. Cross-talk between the salicylic acid-dependent and the salicylic acid-independent pathways provides great regulatory potential for activating multiple resistance mechanisms in varying combinations.     

Micro-assembly of functionalized particulate monolayer on C18-derivatized SiO2 surfaces

This work describes a simple approach to immobilize functionalized colloidal microstructures onto a C(18)-coated SiO(2) substrate via specific or non-specific bio-mediated interactions. Biotinylated bovine serum albumin pre-adsorbed onto a C(18) surface was used to mediate the surface assembly of streptavidin-coated microbeads (2.8 microm), while a bare C(18) surface was used to immobilize anti-Listeria antibody-coated microbeads (2.8 microm) through hydrophobic interactions. For a C(18) surface pre-adsorbed with bovine serum albumin, hydrophobic polystyrene microbeads (0.8 microm) and positively charged dimethylamino microbeads (0.8 microm) were allowed to self-assemble onto the surface. A monolayer with high surface coverage was observed for both polystyrene and dimethylamino microbeads. The adsorption characteristics of Escherichia coli and Listeria monocytogenes on these microbead-based surfaces were studied using fluorescence microscopy. Both streptavidin microbeads pre-adsorbed with biotinylated anti-Listeria antibody and anti-Listeria antibody-coated microbeads showed specific capture of L. monocytogenes, while polystyrene and dimethylamino microbeads captured both E. coli and L. monocytogenes non-specifically. The preparation of microbead-based surfaces for the construction of microfluidic devices for separation, detection, or analysis of specific biological species is discussed.     

Mitochondrial complex I inhibitor rotenone induces apoptosis through enhancing mitochondrial reactive oxygen species production

Inhibition of mitochondrial respiratory chain complex I by rotenone had been found to induce cell death in a variety of cells. However, the mechanism is still elusive. Because reactive oxygen species (ROS) play an important role in apoptosis and inhibition of mitochondrial respiratory chain complex I by rotenone was thought to be able to elevate mitochondrial ROS production, we investigated the relationship between rotenone-induced apoptosis and mitochondrial reactive oxygen species. Rotenone was able to induce mitochondrial complex I substrate-supported mitochondrial ROS production both in isolated mitochondria from HL-60 cells as well as in cultured cells. Rotenone-induced apoptosis was confirmed by DNA fragmentation, cytochrome c release, and caspase 3 activity. A quantitative correlation between rotenone-induced apoptosis and rotenone-induced mitochondrial ROS production was identified. Rotenone-induced apoptosis was inhibited by treatment with antioxidants (glutathione, N-acetylcysteine, and vitamin C). The role of rotenone-induced mitochondrial ROS in apoptosis was also confirmed by the finding that HT1080 cells overexpressing magnesium superoxide dismutase were more resistant to rotenone-induced apoptosis than control cells. These results suggest that rotenone is able to induce apoptosis via enhancing the amount of mitochondrial reactive oxygen species production.