DNA content contributes to nuclear size control in Xenopus laevis

Cells adapt to drastic changes in genome quantity during evolution and cell division by adjusting the nuclear size to exert genomic functions. However, the mechanism by which DNA content within the nucleus contributes to controlling the nuclear size remains unclear. Here, we experimentally evaluated the effects of DNA content by utilizing cell-free Xenopus egg extracts and imaging of in vivo embryos. Upon manipulation of DNA content while maintaining cytoplasmic effects constant, both plateau size and expansion speed of the nucleus correlated highly with DNA content. We also found that nuclear expansion dynamics was altered when chromatin interaction with the nuclear envelope or chromatin condensation was manipulated while maintaining DNA content constant. Furthermore, excess membrane accumulated on the nuclear surface when the DNA content was low. These results clearly demonstrate that nuclear expansion is determined not only by cytoplasmic membrane supply but also by the physical properties of chromatin, including DNA quantity and chromatin structure within the nucleus, rather than the coding sequences themselves. In controlling the dynamics of nuclear expansion, we propose that chromatin interaction with the nuclear envelope plays a role in transmitting chromatin repulsion forces to the nuclear membrane.     

Serum biomarker discovery related to pathogenesis in acute coronary syndrome by proteomic approach

Acute coronary syndrome (ACS) results from inadequate supply of blood flow from the coronary arteries to the heart or ischemia. ACS has an extremely high morbidity and mortality. The levels of biomarkers currently used for detection of ACS also increase in response to myocardial necrosis and other diseases and are not elevated immediately after symptoms appear, thus limiting their diagnostic capacity. Therefore, we aimed to discover new ACS diagnostic biomarkers with high sensitivity and specificity that are specifically related to ACS pathogenesis. Sera from 50 patients with ACS and healthy controls (discovery cohort) each were analyzed using mass spectrometry (MS) to identify differentially expressed proteins, and protein candidates were evaluated as ACS biomarkers in 120 people in each group (validation cohort). α-1-acid glycoprotein 1 (AGP1), complement C5 (C5), leucine-rich α-2-glycoprotein (LRG), and vitronectin (VN) were identified as biomarkers whose levels increase and gelsolin (GSN) as a biomarker whose levels decrease in patients with ACS. We concluded that these biomarkers are associated with the pathogenesis of ACS and can predict the onset of ACS prior to the appearance of necrotic biomarkers.     

Endocytosis of the non-catalytic ADAM23: Recycling and long half-life properties

A Disintegrin And Metalloprotease 23 (ADAM23) is a member of the ADAMs family of transmembrane proteins, mostly expressed in nervous system, and involved in traffic and stabilization of Kv1-potassium channels, synaptic transmission, neurite outgrowth, neuronal morphology and cell adhesion. Also, ADAM23 has been linked to human pathological conditions, such as epilepsy, cancer metastasis and cardiomyopathy. ADAM23 functionality depends on the molecule presence at the cell surface and along the secretory pathway, as expected for a cell surface receptor. Because endocytosis is an important functional regulatory mechanism of plasma membrane receptors and no information is available about the traffic or turnover of non-catalytic ADAMs, we investigated ADAM23 internalization, recycling and half-life properties. Here, we show that ADAM23 undergoes constitutive internalization from the plasma membrane, a process that depends on lipid raft integrity, and is redistributed to intracellular vesicles, especially early and recycling endosomes. Furthermore, we observed that ADAM23 is recycled from intracellular compartments back to the plasma membrane and thus has longer half-life and higher cell surface stability compared with other ADAMs. Our findings suggest that regulation of ADAM23 endocytosis/stability could be exploited therapeutically in diseases in which ADAM23 is directly involved, such as epilepsy, cancer progression and cardiac hypertrophy.     

A Genome-wide RNAi Screen Reveals a Trio-Regulated Rho GTPase Circuitry Transducing Mitogenic Signals Initiated by G Protein-Coupled Receptors

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Highlights? Human cancers harbor frequent mutations in Gq-linked GPCRs and Gα_q subunits ? A genome-wide RNAi screen revealed that Trio is essential for activating AP-1 via Gα_q ? A network of Trio-regulated Rho GTPases and MAPKs links Gq to the nucleus ? A hard-wired Gq-Trio signaling axis promotes the growth of many human malignancies     

Micromorphological observations on leaf and pollen of Capparis L. sect. Capparis (Capparaceae)

Sect. Capparis is represented by a single species, Capparis spinosa L., divided into several intraspecific taxa showing plesiomorphic features and disjunct distributions in the Old World. Leaf surface and pollen features were investigated in the whole group by SEM and light microscope observations. The section is characterized by simple hairs, a reticulate to undulate cuticle, anomocytic stomata surrounded by a peristomal rim, and trizonocolporate, prolate pollen grains. The characteristics of the indumentum appear constant, while the studied taxa are fairly differentiated with respect to cuticular patterns and dimensions of the stomata, and show slight differences in pollen size and exine surface. This micromorphological evidence, coupled with other phenotypic features, supports the placement of this section at the base of the genus Capparis in the paleotropical area. Considering the striking geographic disjunction and symplesiomorphies of the group, its biogeographical and systematic aspects are also discussed.     

Genetic and physical characterisation of the locus controlling columnar habit in apple (Malus × domestica Borkh.)

A better understanding of the genetic control of tree architecture would potentially allow improved tailoring of newly bred apple cultivars in terms of field management aspects, such as planting density, pruning, pest control and disease protection. It would also have an indirect impact on yield and fruit quality. The Columnar (Co) locus strongly suppresses lateral branch elongation and is the most important genetic locus influencing tree architecture in apple. Co has previously been mapped on apple linkage group (LG) 10. In order to obtain fine mapping of Co, both genetically and physically, we have phenotypically analysed and screened three adult segregating experimental populations, with a total of 301 F₁ plants, and one substantial 3-year old population of 1,250 F₁ plants with newly developed simple sequence repeat (SSR) markers, based on the ‘Golden delicious’ apple genome sequence now available. Co was found to co-segregate with SSR marker Co04R12 and was confined in a region of 0.56 cM between SSR markers Co04R11 and Co04R13, corresponding to 393 kb on the ‘Golden delicious’ genome sequence. In this region, 36 genes were predicted, including at least seven sequences potentially belonging to genes that could be considered candidates for involvement in control of shoot development. Our results provide highly reliable, virtually co-segregating markers that will facilitate apple breeding aimed at modifications of the tree habit and lay the foundations for the cloning of Co.     

Methamphetamine Increases Locomotion and Dopamine Transporter Activity in Dopamine D5 Receptor-Deficient Mice

Dopamine regulates the psychomotor stimulant activities of amphetamine-like substances in the brain. The effects of dopamine are mediated through five known dopamine receptor subtypes in mammals. The functional relevance of D5 dopamine receptors in the central nervous system is not well understood. To determine the functional relevance of D5 dopamine receptors, we created D5 dopamine receptor-deficient mice and then used these mice to assess the roles of D5 dopamine receptors in the behavioral response to methamphetamine. Interestingly, D5 dopamine receptor-deficient mice displayed increased ambulation in response to methamphetamine. Furthermore, dopamine transporter threonine phosphorylation levels, which regulate amphetamine-induced dopamine release, were elevated in D5 dopamine receptor-deficient mice. The increase in methamphetamine-induced locomotor activity was eliminated by pretreatment with the dopamine transporter blocker GBR12909. Taken together, these results suggest that dopamine transporter activity and threonine phosphorylation levels are regulated by D5 dopamine receptors.     

Detoxification of Lignocellulose Hydrolysates: Biochemical and Metabolic Engineering Toward White Biotechnology

Chemical hydrolysis of lignocellulosic biomass (LB) produces a number of inhibitors in addition to sugars. These inhibitors include lignin-derived phenolics, carbohydrate-derived furans, and weak acids that have shown a marked effect on the productivities of various metabolites and the growth of biocatalysts in the fermentative reaction. In the past, a number of physicochemical and biological approaches have been proposed to overcome these fermentation inhibitors, including modified fermentative strategies. Additionally, the timely intervention of genetic engineering has provided an impetus to develop suitable technologies for the detoxification of lignocellulosics in biorefineries. However, the improvements in detoxification strategies for lignocellulose hydrolysates have resulted in significant loss of sugars after detoxification. Hydrolysis of myco-LB (LB after fungal pretreatment) has been recognized as a promising approach to avoid fermentation inhibitors and improve total sugar recovery. Biotechnological inventions have also made it possible to widen the range of suitable biocatalysts for biorefineries by microbial-routed induction of enzymatic expression for the elimination of inhibitors, eventually improving ethanol production from acid hydrolysates. This article aims to highlight the strategies that have been adopted to detoxify lignocellulosic hydrolysates and their effects on the chemical composition of the hydrolysates to improve the fermentability of lignocellulosics. In addition, genetic manipulation could widen the availability and variety of substrates and modify the metabolic routes to produce bioethanol or other value-added compounds in an efficient manner.     

Folding Pathways of a Knotted Protein with a Realistic Atomistic Force Field

We report on atomistic simulation of the folding of a natively-knotted protein, MJ0366, based on a realistic force field. To the best of our knowledge this is the first reported effort where a realistic force field is used to investigate the folding pathways of a protein with complex native topology. By using the dominant-reaction pathway scheme we collected about 30 successful folding trajectories for the 82-amino acid long trefoil-knotted protein. Despite the dissimilarity of their initial unfolded configuration, these trajectories reach the natively-knotted state through a remarkably similar succession of steps. In particular it is found that knotting occurs essentially through a threading mechanism, involving the passage of the C-terminal through an open region created by the formation of the native -sheet at an earlier stage. The dominance of the knotting by threading mechanism is not observed in MJ0366 folding simulations using simplified, native-centric models. This points to a previously underappreciated role of concerted amino acid interactions, including non-native ones, in aiding the appropriate order of contact formation to achieve knotting.