Induced pluripotent stem cell‐derived melanocyte precursor cells undergoing differentiation into melanocytes

Induced pluripotent stem cell (iPSC) technology offers a novel approach for conversion of human primary fibroblasts into melanocytes. During attempts to explore various protocols for differentiation of iPSCs into melanocytes, we found a distinct and self‐renewing cell lineage that could differentiate into melanocytes, named as melanocyte precursor cells (MPCs). The MPCs exhibited a morphology distinctive from that of melanocytes, in lacking either the melanosomal structure or the melanocyte‐specific marker genes MITF, TYR, and SOX10. In addition, gene expression studies in the MPCs showed high‐level expression of WNT5A, ROR2, which are non‐canonical WNT pathway markers, and its related receptor TGFβR2. In contrast, MPC differentiation into melanocytes was achieved by activating the canonical WNT pathway using the GSK3β inhibitor. Our data demonstrated the distinct characteristic of MPCs' ability to differentiate into melanocytes, and the underlying mechanism of interfacing between canonical WNT signaling pathway and non‐canonical WNT signaling pathway.     

An empirical model of carbon flow through marine viruses and microzooplankton grazers

Viruses and microzooplankton grazers represent major sources of mortality for marine phytoplankton and bacteria, redirecting the flow of organic material throughout the world's oceans. Here, we investigate the use of nonlinear population models of interactions between phytoplankton, viruses and grazers as a means to quantitatively constrain the flow of carbon through marine microbial ecosystems. We augment population models with a synthesis of laboratory-based estimates of prey, predator and viral life history traits that constrain transfer efficiencies. We then apply the model framework to estimate loss rates in the California Current Ecosystem (CCE). With our empirically parameterized model, we estimate that, of the total losses mediated by viruses and microzooplankton grazing at the focal CCE site, 22 ± 3%, 46 ± 27%, 3 ± 2% and 29 ± 20% were directed to grazers, sloppy feeding (as well as excretion and respiration), viruses and viral lysate respectively. We identify opportunities to leverage ecosystem models and conventional mortality assays to further constrain the quantitative rates of critical ecosystem processes.     

Transient expression of bone morphogenic protein-2 in acute liver injury by carbon tetrachloride

Acute liver injury induced by administration of carbon tetrachloride (CCl4) was shown to be a model of wound-repair in rat liver. Albumin gene expression was significantly reduced at 24 h post injection with CCl4, but recovered at 48 h. We also observed significant and transient expression of bone morphogenic protein-2 (BMP-2) at 6-24 h post treatment. This expression was also shown with depletion of Kupffer cell by GdCl3, and immunostaining with anti-BMP-2 antibody showed BMP-2-producing cells interspersed in intralobular spaces of injured liver. These observations suggest that BMP-2 secreted from oval-like cells plays important roles in the wound healing response of injured liver.     

Phosphorylation of adult type Sept5 (CDCrel-1) by cyclin-dependent kinase 5 inhibits interaction with syntaxin-1

Increasing evidence implicates cyclin-dependent kinase 5 (Cdk5) in neuronal synaptic function. We searched for Cdk5 substrates in synaptosomal fractions prepared from mouse brains. Mass spectrometric analysis after two-dimensional SDS-PAGE identified several synaptic proteins phosphorylated by Cdk5-p35; one protein identified was Sept5 (CDCrel-1). Although septins were isolated originally as cell division-related proteins in yeast, Sept5 is expressed predominantly in neurons and is implicated in exocytosis. We confirmed that Sept5 is phosphorylated by Cdk5-p35 in vitro and identified Ser17 of adult type Sept5 (Sept5_v1) as a major phosphorylation site. We found that Ser17 of Sept5_v1 is phosphorylated in mouse brains. Coimmunoprecipitation from synaptosomal fractions and glutathione S-transferase-syntaxin-1A pulldown assays of Sept5_v1 expressed in COS-7 cells showed that phosphorylation of Sept5_v1 by Cdk5-p35 decreases the binding to syntaxin-1. These results indicate that the interaction of Sept5 with syntaxin-1 is regulated by the phosphorylation of Sept5_v1 at Ser17 by Cdk5-p35.     

Line thinning enhances diversity of Coleoptera in overstocked Cryptomeria japonica plantations in central Japan

We evaluated the effectiveness of line thinning, a new silvicultural technique, toward restoring diversity of Coleoptera in overstocked Cryptomeria japonica D. Don plantations in central Japan. We compared the abundance of some common Coleoptera families between line-thinned stands and adjacent unthinned stands in two plantations: low-elevation Sugi site (4 years since thinning) and high-elevation Kuchiotani site (6 years since thinning). Many bettle families comprising various functional groups such as plant feeders, wood borers, rotten wood feeders, root feeders, fungus feeders, dung feeders, and scavengers were more abundant in the line-thinned stands than in the unthinned stands. Furthermore, some important families were missing from the unthinned stands. There were strong positive relationships between Coleopteran abundance and understory vegetation. Our results suggest that line thinning may potentially increase biodiversity in overstocked C. japonica plantations by restoring important ecological processes such as food-web interactions (pollination, predation, herbivory, decomposition, parasitism, etc.), and habitat conditions.     

Frontiers in glycomics; bioinformatics and biomarkers in disease. September 11-13, 2006 Natcher Conference Center, NIH Campus, Bethesda, MD, USA

This is a short summary of a meeting entitled "The Frontiers in Glycomics; Bioinformatics and Biomarkers in Disease" which was jointly organized by the NIH Consortium for Functional Glycomics (CFG), Human Disease Glycomics/Proteome Initiative (HGPI), National Cancer Institute, National Institute of General Medical Sciences, Japan Society for the Promotion of Science and National Center for Research Resources held at the NIH Campus, Bethesda, MD, Natcher Conference Center in September 11-13, 2006.     

Effects of dietary protein contents and habitual endurance exercise on supplemental leucine oxidation in mice

The effects of dietary protein contents and regular exercise on the oxidation of supplemented leucine were examined. In the short-term study, male BALB/cCrSlc mice were fed diets containing 0, 10, 20, 35, and 60% protein: energy ratios for 1 week. In the long-term study, exercised and sedentary mice were fed diets containing 20, 35, and 60% protein ratios for 9 weeks. After the feeding periods, the mice were a bolus administered oral supplements of l-[1-¹³C] leucine. Expired gas was analyzed, and oxidized leucine was expressed as a relative ¹³CO₂/¹²CO₂ ratio. In the short-term study, the peak ¹³CO₂/¹²CO₂ ratio significantly increased with diet protein concentrations. Moreover, the long-term study also showed that the peak ¹³CO₂/¹²CO₂ ratio was significantly increased by high protein diets in both exercised and sedentary mice. Our results indicate that supplemental leucine oxidation is associated with consumption of a high-protein diet, irrespective of exercise status.

Abbreviations: AUC: area under the curve; EX: exercise; RQ: respiratory quotient; SED: sedentary; VO₂/W: oxygen uptake per body weight     

Diverse effects of poly-basic amino acids, heparin and ionic strength on the phosphorylation of various substrates by cytosolic protein-tyrosine kinase from porcine spleen

1. Effects of poly-basic amino acids, heparin and ionic strength on the activity of cytosolic protein-tyrosine kinase from porcine spleen (CPTK-40) have been studied. 2. Both polylysine and polyarginine stimulated the phosphorylation of [Val5]angiotensin II and E11 G1 (synthetic peptide of EDAEYAARRRG), but could neither stimulate nor inhibit the phosphorylation of random copolymers; poly(EY)4:1 and poly(EAY)6:3:1. 3. Heparin stimulated the phosphorylation of poly(EY)4:1 by 2.5-fold, however, it inhibited those of E11G1, poly(EAY)6:3:1, casein and H2B histone. 4. Elevation of ionic strength of either NaCl, KCl or (NH4)2SO4 stimulated the phosphorylation of poly(EY)4:1 by greater than 5-fold, but inhibited those of casein, tubulin, H2B histone, E11G1 and poly(EAY)6:3:1. 5. These effectors did not change the Km for substrates but increased the Vmax. 6. These results suggest that the effects of poly-basic amino acids, heparin and ionic strength on the activity of CPTK-40 are mainly on the substrates employed rather than on the enzyme itself.