Study on the Synthesis and Adsorption Properties of KH-560 Modified PalygorskiteSupported β-Cyclodextrin

1 Results Palygorskite (PGS) is a chain-layer magnesium-aluminum silicate mineral. Because of its developed interior channels and large specific surface area, and thus considerable adsorption capacity, it has been studied for the application as one of environmental mineral adsorbents[1-3]. Cyclodextrins (CD) possess a hydrophilic exterior and a hydrophobic interior into which a variety of hydrophobic organic molecules maybe introduced. The CD molecule not only affects a hydrophilic cavity on the nanometer scale, generally smaller than the zeolitic cavities, but also possesses hydrophilic hydroxyl groups outside the cavity, which contribute to the solubility of CD in water[4-5].     

Ceramides induce apoptosis in HeLa cells and enhance cytochrome c-induced apoptosis in Xenopus egg extracts

Ceramide has been reported to induce typical apoptotic changes in nuclei incubated in a cell-free system, and that the addition of ceramide bypasses the requirement for mitochondria. Here, we explore the possible pathways by which ceramide induces apoptosis either in intact cells or in a cell-free system which we have developed. We found that in the cell-free system, C2-ceramide is not able to induce apoptosis in nuclei whereas cytochrome c does, but it is able to induce HeLa cells to undergo apoptosis. Ceramide is also not able to induce apoptosis when added into the cell-free system together with purified mitochondria. Further investigation showed that C2-ceramide at certain concentrations greatly increases nuclear apoptosis caused by cytochrome c in the cell-free system. From these results we conclude that the induction of apoptosis by ceramide may require intact cells in which some unknown signal transduction pathways are involved.     

Adducin: structure, function and regulation

Adducin is a ubiquitously expressed membrane-skeletal protein localized at spectrin-actin junctions that binds calmodulin and is an in vivo substrate for protein kinase C (PKC) and Rho-associated kinase. Adducin is a tetramer comprised of either alpha/beta or alpha/gamma heterodimers. Adducin subunits are related in sequence and all contain an N-terminal globular head domain, a neck domain and a C-terminal protease-sensitive tail domain. The tail domains of all adducin subunits end with a highly conserved 22-residue myristoylated alanine-rich C kinase substrate (MARCKS)-related domain that has homology to MARCKS protein. Adducin caps the fast-growing ends of actin filaments and also preferentially recruits spectrin to the ends of filaments. Both the neck and the MARCKS-related domains are required for these activities. The neck domain self-associates to form oligomers. The MARCKS-related domain binds calmodulin and contains the major phosphorylation site for PKC. Calmodulin, gelsolin and phosphorylation by the kinase inhibit in vitro activities of adducin involving actin and spectrin. Recent observations suggest a role for adducin in cell motility, and as a target for regulation by Rho-dependent and Ca2+-dependent pathways. Prominent physiological sites of regulation of adducin include dendritic spines of hippocampal neurons, platelets and growth cones of axons.     

Current applications of single-cell PCR

The advent of the polymerase chain reaction (PCR) has revolutionised the way in which molecular biologists view their task at hand, for it is now possible to amplify and examine minute quantities of rare genetic material: the limit of this exploration being the single cell. It is especially in the field of prenatal diagnostics that this ability has been readily seized upon, as it has opened up the prospect of preimplantation genetic analysis and the use of fetal cells enriched from the blood of pregnant women for the assessment of single-gene Mendelian disorders. However, apart from diagnostic applications, single-cell PCR has proven to be of enormous use to basic scientists, addressing diverse immunological, neurological and developmental questions, where both the genome but also messenger RNA expression patterns were examined. Furthermore, recent advances, such as optimised whole genome amplification (WGA) procedures, single-cell complementary DNA arrays and perhaps even single-cell comparative genomic hybridisation will ensure that the genetic analysis of single cells will become common practice, thereby opening up new possibilities for diagnosis and research.     

Fgf8 signalling from the AER is essential for normal limb development

Vertebrate limb development depends on signals from the apical ectodermal ridge (AER), which rims the distal tip of the limb bud. Removal of the AER in chick results in limbs lacking distal skeletal elements. Fibroblast growth factor (FGF) proteins can substitute for the AER (refs 4-7), suggesting that FGF signalling mediates AER activity. Of the four mouse Fgf genes (Fgf4 , Fgf8, Fgf9, Fgf17) known to display AER-specific expression domains within the limb bud (AER-Fgfs), only Fgf8 is expressed throughout the AER. Moreover, Fgf8 expression precedes that of other AER-Fgfs (refs 8-13), suggesting that Fgf8 may perform unique functions early in limb development. In mice, loss of function of Fgf4 (refs 13,14), Fgf9 (D. Ornitz, pers. comm.) or Fgf17 (ref. 15) has no effect on limb formation. We report here that inactivating Fgf8 in early limb ectoderm causes a substantial reduction in limb-bud size, a delay in Shh expression, misregulation of Fgf4 expression, and hypoplasia or aplasia of specific skeletal elements. Our data identify Fgf8 as the only known AER-Fgf individually necessary for normal limb development, and provide insight into the function of Fgf signalling from the AER in the normal outgrowth and patterning of the limb.