CRUMPLED LEAF (CRL) homologs of Physcomitrella patens are involved in the complete separation of dividing plastids

Plastid division is controlled by numerous nuclear genes. Arabidopsis thaliana CRUMPLED LEAF (AtCRL) is a plastid division-related gene, and the crl mutant exhibits a dwarf phenotype with abnormal cell division and a significant reduction in plastid numbers. However, the function of AtCRL is not fully understood. Here, we identified and characterized two AtCRL homologs, PpCRL1 and PpCRL2, in the moss Physcomitrella patens. PpCRL1 and PpCRL2 shared 77% amino acid identity with each other and 47% identity with AtCRL. Single PpCRL1 or -2 gene knockout (KO) mutants could not be distinguished from the wild-type mosses, but PpCRL1 and -2 double KO mutants displayed growth retardation of protonemata and gametophores and harbored approximately 10 large chloroplasts per cell. This indicates that PpCRL1 and PpCRL2 have redundant functions in chloroplast division and plant growth. Unlike the A. thaliana crl mutants, however, the PpCRL double KO mutants did not display abnormal orientation of the cell division plane. Complementation experiments showed that AtCRL partially rescued the defects in chloroplast size and number of the PpCRL double KO mutant. This suggests that PpCRL has a similar, but not identical, function to AtCRL. Time-lapse microscopic observation of the double PpCRL KO mutants revealed that some dumbbell-shaped chloroplasts failed to complete division at the late stage of plastid division; enlarged chloroplasts were thus generated. This strongly suggests that PpCRLs are involved in the complete separation of dividing chloroplasts.     

A Disintegrin and Metalloprotease 10 (ADAM10) Is Indispensable for Maintenance of the Muscle Satellite Cell Pool

Satellite cells (SCs) are muscle-specific stem cells that are essential for the regeneration of damaged muscles. Although SCs have a robust capacity to regenerate myofibers, the number of SCs decreases with aging, leading to insufficient recovery after muscle injury. We herein show that ADAM10 (a disintegrin and metalloprotease 10), a membrane-bound proteolytic enzyme with a critical role in Notch processing (S2 cleavage), is essential for the maintenance of SC quiescence. We generated mutant mice in which ADAM10 in SCs can be conditionally abrogated by tamoxifen injection. Tamoxifen-treated mutant mice did not show any apparent defects and grew normally under unchallenged conditions. However, these mice showed a nearly complete loss of muscle regeneration after chemically induced muscle injury. In situ hybridization and flow cytometric analyses revealed that the mutant mice had significantly less SCs compared with wild type controls. Of note, we found that inactivation of ADAM10 in SCs severely compromised Notch signaling and led to dysregulated myogenic differentiation, ultimately resulting in deprivation of the SC pool in vivo. Taken together, the present findings underscore the role of ADAM10 as an indispensable component of Notch signaling in SCs and for maintaining the SC pool.     

Multi-PK antibodies: Powerful analytical tools to explore the protein kinase world

Diverse biological events are regulated through protein phosphorylation mediated by protein kinases. Some of these protein kinases are known to be involved in the pathogenesis of various diseases. Although 518 protein kinase genes were identified in the human genome, it remains unclear how many and what kind of protein kinases are expressed and activated in cells and tissues under varying situations. To investigate cellular signaling by protein kinases, we developed monoclonal antibodies, designated as Multi-PK antibodies, that can recognize multiple protein kinases in various biological species. These Multi-PK antibodies can be used to profile the kinases expressed in cells and tissues, identify the kinases of special interest, and analyze protein kinase expression and phosphorylation state. Here we introduce some applications of Multi-PK antibodies to identify and characterize the protein kinases involved in epigenetics, glucotoxicity in type 2 diabetes, and pathogenesis of ulcerative colitis. In this review, we focus on the recently developed technologies for kinomics studies using the powerful analytical tools of Multi-PK antibodies.     

Axial dispositions and conformations of myosin crossbridges along thick filaments in relaxed and contracting states of vertebrate striated muscles by X-ray fiber diffraction

X-ray diffraction patterns from live vertebrate striated muscles were analyzed to elucidate the detailed structural models of the myosin crown arrangement and the axial disposition of two-headed myosin crossbridges along the thick filaments in the relaxed and contracting states. The modeling studies were based upon the previous notion that individual myosin filaments had a mixed structure with two regions, a "regular" and a "perturbed". In the relaxed state the distributions and sizes of the regular and perturbed regions on myosin filaments, each having its own axial periodicity for the arrangement of crossbridge crowns within the basic period, were similar to those reported previously. A new finding was that in the contracting state, this mixed structure was maintained but the length of each region, the periodicities of the crowns and the axial disposition of two heads of a crossbridge were altered. The perturbed regions of the crossbridge repeat shifted towards the Z-bands in the sarcomere without changing the lengths found in the relaxed state, but in which the intervals between three successive crowns within the basic period became closer to the regular 14.5-nm repeat in the contracting state. In high resolution modeling for a myosin head, the two heads of a crossbridge were axially tilted in opposite directions along the three-fold helical tracks of myosin filaments and their axial orientations were different from each other in perturbed and regular regions in both states. Under relaxing conditions, one head of a double-headed crossbridge pair appeared to be in close proximity to another head in a pair at the adjacent crown level in the axial direction in the regular region. In the perturbed region this contact between heads occurred only on the narrower inter-crown levels. During contraction, one head of a crossbridge oriented more perpendicular to the fiber axis and the partner head flared axially. Several factors that significantly influence the intensities of the myosin based-meridional reflections and their relative contributions are discussed.     

Enrichment of longevity phenotype in mtDNA haplogroups D4b2b, D4a, and D5 in the Japanese population

We report new results from the re-analysis of 672 complete mitochondrial (mtDNA) genomes of unrelated Japanese individuals stratified into seven equal sized groups by the phenotypes: diabetic patients, diabetic patients with severe angiopathy, healthy non-obese young males, obese young males, patients with Alzheimer’s disease, patients with Parkinson’s disease and centenarians. Each phenotype had 96 samples over 27 known haplogroups: A, B4a, B4b, B4c, B*, B5, D*, F1, F2, M*, M7a, M7b, M8, M9, D4a, D4b1, D4b2, D4d, D4e, D4g, D4h, D5, G, Z, M*, N9a, and N9b. A t-test comparing the fraction of samples in a haplogroup to healthy young males showed a significant enrichment of haplogroups D4a, D5, and D4b2 in centenarians. The D4b2 enrichment was limited to a subgroup of 40 of 61 samples which had the synonymous mutation 9296C > T. We identified this cluster as a distinct haplogroup and labeled it as D4b2b. Using an exhaustive procedure, we constructed the complete list of “mutation patterns” for centenarians and showed that the most significant patterns were in D4a, D5, and D4b2b. We argue that if a selection for longevity appeared only once, it was probably an autosomal event which could be dated to after the appearance of the D mega-group but before the coalescent time of D4a, D5, and D4b2b. Using a simple procedure, we estimated that this event occurred 24.4 ± 0.9 kYBP. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Gabriela Alexe and Noriyuki Fuku are joint first authors.     

Rapid and onsite BOD sensing system using luminous bacterial cells-immobilized chip

A BOD monitoring system based on a bio-chip which immobilized luminous bacterium in micrometer-order holes were arrayed and fabricated by micro-machine techniques, was developed. The acrylic chip (3 cmx3 cm) comprises nine micro-holes (diameter: 700 microm or 1 mm, depth: 100 microm) arranged in a three by three array. Cells of the marine luminous bacterium, Photobacterium phosphoreum IFO 13896, which was grown at 15 degrees C for 15 h, were immobilized with 3% or 15% sodium alginate gel. BOD standard solutions or actual sample solution (approximately 10 microl) was fallen onto the cell-arrayed chip, and then the chip was incubated at 25 degrees C for 25 min. After incubation, bioluminescence from the each hole was gray-scaled and measured by a chemi-imager or newly developed onsite-type-monitoring system using a digital camera and a mobile-type personal computer. BOD values less than 16 ppm could detect by the chip, in particular, linear relationship at the concentrations between 0 and 16 ppm could be observed when luminous cells were immobilized with 3% sodium alginate gel. Steady bioluminescence was observed on the chip in the presence of BOD standard solution (GGA solution) which contained mineral elements. Furthermore, simultaneous detection of BOD values in various samples could be employed in the single chip. These results showed that the monitoring system with bio-chip could achieve high-through-put and onsite BOD detection. Our newly developed onsite-type BOD detection system which was used a digital camera and a (mobile) laptop computer was applied to measure and detect organic pollution due to biodegradable substances in wastewater treatment system. The same performance as the chemi-imager system was obtained for data of bioluminescence. The obtained BOD values showed a similar correlation with that of the conventional method for BOD determination (BOD5). These results suggested for successful achievement of high-though-put and onsite detection of BOD in practical.     

Natural dental caries in molars of osteogenic disorder Shionogi rats

Osteogenic disorder Shionogi (ODS) rats are genetically defective in ascorbic acid biosynthesis. They exhibit a gait abnormality due to dysfunctional bone formation and display various dental abnormalities. Conditions of the oral cavity and tooth quality both influence the development of dental caries. This study was designed to determine the characteristics of dental caries in ODS/ ShiJclod/od rats. Caries were scored and compared among ODS/ShiJclod/od, ODS/ShiJcl+/+, and Jcl:Wistar retired breeders. Among male rats, the caries scores of the ODS/ShiJclod/od and ODS/ShiJcl+/+ groups were similar to each other but greater than those in Jcl:Wistar rats, whereas among female rats, caries scores in ODS/ShiJclod/od animals were equivalent to or somewhat greater than those in ODS/ShiJcl+/+ rats, whose scores were markedly greater than those of Jcl:Wistar rats. The results suggest that ODS/ShiJcl rats were more susceptible to dental caries than were Jcl:Wistar rats. Under the conditions of the study, caries scores between ODS/ ShiJclod/od and ODS/ShiJcl+/+ rats differed only among parous females.