Design of a Wide Ranging Highly Sensitive Pressure Sensor Based on Two-Dimensional Photonic Crystals

Plasmonics - A highly sensitive pressure sensor operating over a wide pressure range based on two-dimensional photonic crystals having a Mach-Zehnder interferometer structure has been developed....     

Structural differences in centromeric heterochromatin are spatially reconciled on fertilisation in the mouse zygote

In mammals, paternal and maternal pronuclei undergo profound chromatin reorganisation upon fertilisation. How these events are orchestrated within centromeric regions to ensure proper chromosome segregation in the following cellular divisions is unknown. In this study, we followed the dynamic unfolding of the centromeric regions, i.e. the centric and pericentric satellite repeats, by DNA fluorescent in situ hybridization (FISH) during the first cell cycle up to the two-cell stage. The distinct chromatin from female and male gametes both undergo rapid remodelling and reach a zygotic organisation in which the satellites occupy restricted spatial domains surrounding the nucleolar precursor body. A transition from this zygotic to a somatic cell-like organisation takes place during the two-cell stage. Using 3D immuno-FISH, we find that, whereas maternal pericentric regions are marked with H3K9me3, H4K20me3 and HP1β, paternal ones only showed HP1β marking. Thus, despite different chromatin features, male and female pronuclei organise their centromeric regions in the same way within the nuclei to align chromosomes on the metaphase plate and segregate them appropriately. Our findings highlight the importance of ensuring a proper centromere function while preserving the distinction of parental genome origin during the return to totipotency in the zygote. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Cucurbitacins from Ecballium elaterium juice increase the binding of bilirubin and ibuprofen to albumin in human plasma

Ecballium elaterium, a medicinal plant, whose fruit juice is used for the treatment of jaundice in folk medicine, has been reported as being capable of decreasing bilirubinemia in animals with jaundice [H.H. Elayan, M.N. Garaibeh, S.M. Zmeili, S.A. Salhab, Effects of Ecballium elaterium juice on serum bilirubin concentration in male rats, Int. J. Crude Drug Res. 27 (1989) 227-234]. The aim of this study is to identify the Ecballium elaterium components, which are able to modify the binding of bilirubin to albumin. The juice is fiber-free but contains proteins, lipids, sugars, and minerals. The extract of the juice, analyzed by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS), contains cucurbitacins (Cuc) B, D, E, and I as well as several glycosylated compounds. Human plasma containing no or serial concentrations of Ecballium elaterium components were prepared and the direct bilirubin (DB) and total bilirubin (TB) were determined by the Jendrassik and Grof method. Our results showed that Cuc D, E, and B decreased the levels of DB and TB in plasma, while Cuc I, glycosyl derivatives, and proteins of the juice did not modify the bilirubin levels. The binding of domain specific ligands to HSA, bilirubin (domain IIA), and ibuprofen (domain IIIA), were studied in the absence and presence of Cuc D, E, and I, by fluorescence spectroscopy. The values of binding constant K(a) and binding site number n, determined by Scatchard method, increased for the both ligands only in the presence of Cuc E and D. Cuc I decreased slightly the K(a) of ibuprofen, suggesting an interaction with the domain IIIA of the protein. As a conclusion, Cuc E, D, and B produce rearrangement in the structure of albumin leading to increase the binding of domain specific ligands, ibuprofen and bilirubin.     

Cell-cell fusion

Cell-cell fusion is a highly regulated and dramatic cellular event that is required for development and homeostasis. Fusion may also play a role in the development of cancer and in tissue repair by stem cells. While virus-cell fusion and the fusion of intracellular membranes have been the subject of intense investigation during the past decade, cell-cell fusion remains poorly understood. Given the importance of this cell-biological phenomenon, a number of investigators have begun analyses of the molecular mechanisms that mediate the specialized fusion events of a variety of cell types and species. We discuss recent genetic and biochemical studies that are beginning to yield exciting insights into the fusion mechanisms of Saccharomyces cerevisiae mating pairs, Caenorhabditis elegans epithelial cells and gametes, Drosophila melanogaster and mammalian myoblasts, and mammalian macrophages.     

Exceptionally preserved North American Paleogene metatherians: adaptations and discovery of a major gap in the opossum fossil record

A major gap in our knowledge of the evolution of marsupial mammals concerns the Paleogene of the northern continents, a critical time and place to link the early history of metatherians in Asia and North America with the more recent diversification in South America and Australia. We studied new exceptionally well-preserved partial skeletons of the Early Oligocene fossil Herpetotherium from the White River Formation in Wyoming, which allowed us to test the relationships of this taxon and examine its adaptations. Herpetotheriidae, with a fossil record extending from the Cretaceous to the Miocene, has traditionally been allied with opossums (Didelphidae) based on fragmentary material, mainly dentitions. Analysis of the new material reveals that several aspects of the cranial and postcranial anatomy, some of which suggests a terrestrial lifestyle, distinguish Herpetotherium from opossums. We found that Herpetotherium is the sister group to the crown group Marsupialia and is not a stem didelphid. Combination of the new palaeontological data with molecular divergence estimates, suggests the presence of a long undocumented gap in the fossil record of opossums extending some 45Myr from the Early Miocene to the Cretaceous.