Genetically engineered multicistronic allele of Pmel yielding highly specific CreERT2-mediated recombination in the melanocyte lineage

Genetic approaches that allow lineage tracing are essential to our future understanding of melanocytes and melanoma. To date, the approaches used to label melanocytes in mice have relied on random integration of transgenes driven by the promoters of the Tyrosinase and Dopachrome tautomerase genes, knock-in to the Dopachrome tautomerase locus or knock-in to the Mlana locus in a bacterial artificial chromosome. These strategies result in expression in other tissues such as telencephalon and other cell types such as nerves. Here we used homologous recombination in mouse embryonic stem cells to generate a targeted multicistronic allele of the Pmel locus that drives melanocyte-specific expression of CreERT2, nuclear localised H2B-Cerulean and membrane localised marcks-mKate2 allowing live imaging of melanocytes and activation of other conditional alleles. We combined this allele with R26R-EYFP mice allowing induction of EYFP expression on administration of tamoxifen or its metabolite 4-OHT. The fluorescent proteins H2B-Cerulean and marcks-mKate2 label the cell nucleus and plasma membrane respectively allowing live imaging and FACS isolation of melanoblasts and melanocytes as well as serving to provide an internal control allowing estimation of recombination efficiency after administration of tamoxifen. We demonstrate the utility of the transgene in embryonic and adult tissues.

Novel Mixed Matrix Membranes Based on Polymer of Intrinsic Microporosity PIM-1 Modified with Metal-Organic Frameworks for Removal of Heavy Metal Ions and Food Dyes by Nanofiltration

Nowadays, nanofiltration is widely used for water treatment due to its advantages, such as energy-saving, sustainability, high efficiency, and compact equipment. In the present work, novel nanofiltration membranes based on the polymer of intrinsic microporosity PIM-1 modified by metal-organic frameworks (MOFs)-MIL-140A and MIL-125-were developed to increase nanofiltration efficiency for the removal of heavy metal ions and dyes. The structural and physicochemical properties of the developed PIM-1 and PIM-1/MOFs membranes were studied by the spectroscopic technique (FTIR), microscopic methods (SEM and AFM), and contact angle measurement. Transport properties of the developed PIM-1 and PIM-1/MOFs membranes were evaluated in the nanofiltration of the model and real mixtures containing food dyes and heavy metal ions. It was found that the introduction of MOFs (MIL-140A and MIL-125) led to an increase in membrane permeability. It was demonstrated that the membranes could be used to remove and concentrate the food dyes and heavy metal ions from model and real mixtures.

PLAA Mutations Cause a Lethal Infantile Epileptic Encephalopathy by Disrupting Ubiquitin-Mediated Endolysosomal Degradation of Synaptic Proteins

During neurotransmission, synaptic vesicles undergo multiple rounds of exo-endocytosis, involving recycling and/or degradation of synaptic proteins. While ubiquitin signaling at synapses is essential for neural function, it has been assumed that synaptic proteostasis requires the ubiquitin-proteasome system (UPS). We demonstrate here that turnover of synaptic membrane proteins via the endolysosomal pathway is essential for synaptic function. In both human and mouse, hypomorphic mutations in the ubiquitin adaptor protein PLAA cause an infantile-lethal neurodysfunction syndrome with seizures. Resulting from perturbed endolysosomal degradation, Plaa mutant neurons accumulate K63-polyubiquitylated proteins and synaptic membrane proteins, disrupting synaptic vesicle recycling and neurotransmission. Through characterization of this neurological intracellular trafficking disorder, we establish the importance of ubiquitin-mediated endolysosomal trafficking at the synapse.

Environmentally benign and diastereoselective synthesis of 2,4,5-trisubstituted-2-imidazolines

A one-pot, membrane-assisted synthesis of 2,4,5-trisubstituted-2-imidazolines was developed, and substituent effects, reaction kinetics and mechanism by DFT were studied.

Enhanced gas separation factors of microporous polymer constrained in the channels of anodic alumina membranes

New composite membranes based on porous anodic alumina films and polymer of intrinsic microporosity (PIM-1) have been prepared using a spin-coating technique. According to scanning electron microscopy, partial penetration of polymer into the pores of alumina supports takes place giving rise to selective polymeric layers with fiber-like microstructure. Geometric confinement of rigid PIM-1 in the channels of anodic alumina causes reduction of small-scale mobility in polymeric chains. As a result, transport of permanent gases, such as CH4, becomes significantly hindered across composite membranes. Contrary, the transport of condensable gases (CO2, С4H10), did not significantly suffer from the confinement due to high solubility in the polymer matrix. This strategy enables enhancement of selectivity towards CO2 and C4H10 without significant loss of the membrane performance and seems to be prospective for drain and sweetening of natural gas.

Germline melanocortin-1-receptor genotype is associated with severity of cutaneous phenotype in congenital melanocytic nevi: a role for MC1R in human fetal development

Congenital melanocytic nevi (CMN) are pigmented birthmarks that affect up to 80% of the skin surface area. The increased frequency of CMN in families of severely affected individuals is suggestive of a predisposing germline genotype. We noted a high prevalence of red hair in affected families, and considered a role for MC1R in this condition. A cohort of 166 CMN subjects underwent pigmentary phenotyping, with MC1R genotyping in 113. Results were compared with a local control group of 60 unrelated children and with 300 UK children without CMN. CMN subjects had higher prevalences of red hair and a red-haired parent than local controls and had a higher rate of compound heterozygosity and homozygosity for MC1R variants. The presence of a V92M or R allele (D84E, R151C, R160W, D294H) was associated with increasing size of the CMN, implying a growth-promoting effect of these alleles. Unexpectedly, the V92M and R151C alleles were also strongly associated with birth weight in the CMN cohort, a finding confirmed in the control group. The effect of germline MC1R genotype on development and severity of CMN led us to investigate potential broader effects on growth, revealing a role for MC1R in normal fetal development.

Human and mouse mutations in WDR35 cause short-rib polydactyly syndromes due to abnormal ciliogenesis

Defects in cilia formation and function result in a range of human skeletal and visceral abnormalities. Mutations in several genes have been identified to cause a proportion of these disorders, some of which display genetic (locus) heterogeneity. Mouse models are valuable for dissecting the function of these genes, as well as for more detailed analysis of the underlying developmental defects. The short-rib polydactyly (SRP) group of disorders are among the most severe human phenotypes caused by cilia dysfunction. We mapped the disease locus from two siblings affected by a severe form of SRP to 2p24, where we identified an in-frame homozygous deletion of exon 5 in WDR35. We subsequently found compound heterozygous missense and nonsense mutations in WDR35 in an independent second case with a similar, severe SRP phenotype. In a mouse mutation screen for developmental phenotypes, we identified a mutation in Wdr35 as the cause of midgestation lethality, with abnormalities characteristic of defects in the Hedgehog signaling pathway. We show that endogenous WDR35 localizes to cilia and centrosomes throughout the developing embryo and that human and mouse fibroblasts lacking the protein fail to produce cilia. Through structural modeling, we show that WDR35 has strong homology to the COPI coatamers involved in vesicular trafficking and that human SRP mutations affect key structural elements in WDR35. Our report expands, and sheds new light on, the pathogenesis of the SRP spectrum of ciliopathies.

Human lead exposure in England from approximately 5500 BP to the 16th century AD

Lead concentration and isotope ratio data are presented for the tooth enamel of 77 individuals buried in England and spanning approximately 5000 years from the Neolithic until the 16th century AD. Whereas other tissues may be affected by diagenesis in the burial environment, the Pb concentration of tooth enamel is directly related to childhood exposure. This record is preserved post-mortem and over archaeological time. Tooth enamel Pb concentrations in the prehistoric period appear to be variable within the range 0.04 to approximately 0.4 ppm, with occasional higher levels. The Romano-British and medieval periods show a marked increase in Pb exposures with enamel concentrations reaching up to approximately 40 ppm. These exposures would today be associated with industrial pollution. Exposures appear to be highly variable compared with modern people, however, with many medieval individuals having very low enamel Pb concentrations comparable with prehistoric people. Lead isotope data refine this picture. We distinguish between the diverse isotopic ratios we believe to be characteristic of 'natural' exposure to Pb-from geological sources via the diet-and the much narrower isotopic range characteristic of exposure to technological Pb from ore sources. Taken together the data suggest that the maximum concentrations associated with 'non-technological' exposure at any period are approximately 0.5-1.0 ppm, similar to that reported for modern people in England.

The distribution of lead within ancient and modern human teeth: implications for long-term and historical exposure monitoring

The preservation of lead within human tissue makes it possible to monitor long-term exposure to the element and to model changing sources of lead pollution throughout the lifetime of an individual. Dental tissues have recently been shown to be particularly useful for this purpose. Enamel, for instance, forms at known stages of life and is chemically stable in vivo whereas dentine is remodelled in a predictable fashion. The relative stability of enamel is reflected in its excellent post-mortem preservation. This raises the possibility of using historical or archaeological material to reconstruct long-term trends and establish baseline data relating to exposure among pre-industrial or even prehistoric populations. The use of archaeological material is currently problematic, however, because of the site-specific nature of diagenesis and incomplete understanding of its chemistry, particularly in respect of lead uptake into dental tissue from the burial environment. A detailed study of lead distribution within both ancient and modern human teeth is presented. Conclusions are drawn on the pattern of lead distribution resulting from tissue formation and the manner of its alteration in the burial environment. In particular, attention is drawn to a consistent enrichment of lead within the outer 30 microns of the enamel of both ancient and modern teeth which appears to be unrelated to diagenesis. The implications for current approaches to long-term monitoring and for the reconstruction of historical and archaeological exposure patterns are discussed.

Genetics and molecular biology of mouse pigmentation

The formation of mouse coat color is a relatively complex developmental process that is affected by a large number of mutations, both naturally occurring and induced. The cloning of the genes in which these mutations occur and the elucidation of the mechanisms by which these mutations disrupt the normal pigmentation pattern is leading to an understanding of the way interactions between gene products lead to a final phenotype.

Affinity thin-layer chromatography test of the immunoreactive fraction of radiolabeled antibodies

A simple, rapid and self-contained system for assaying the immunoreactive fraction of radiolabeled antibodies was developed using affinity thin-layer chromatography (ATLC). ATLC combines use of solid-phase-bound antigen and conventional TLC. The technique is an improvement over existing means of measuring immunoreactive fraction (bead-type or cell-type assays) in that it has neither wash steps nor centrifugation steps, yet provides results essentially identical to those obtained with the more time-consuming assays. ATLC is accomplished using chromatography strips that are coated with antigen material in a discrete region near the origin. The antigen-coated strips are then blocked in serum, air-dried and stored. For use, radiolabeled antibody is spotted at the origin, and the strip is developed using a buffered solvent. Immunoreactive antibody binds to the antigen at or near the origin, while radioactivity not associated with immunoreactive antibody migrates with the solvent front. Antigen-negative strips (serum-blocked only) are used to measure "nonspecific" binding. The ATLC development time is about 16 min, and the results can be obtained in about 30 min. The assay described in this report uses antigens from colon tumor and is suitable for use with B72.3 and other colon cancer-reactive antibodies.

Quantitation of radiolabeled antibody binding to cells by thin-layer chromatography

Thin layer chromatography (TLC) was used to monitor binding of radiolabeled antibodies to cells. Labeled antibodies were reacted with cells and aliquots chromatographed on serum-blocked, ITLC strips. The cell-antibody complexes remain at the origin and unbound antibody migrates with the solvent front. The antibody binding was estimated from the ratio of radioactivity at the origin compared to the total applied. Separations are completed in about 10 min. This method does not use centrifugation or wash steps, and provides an inexpensive and self-contained system to evaluate radioligand binding. Cell binding assay results using this method are approximately the same as those obtained using bead- or cell-type assays.