Liana abundance and relationships to sapling and tree hosts in an East African primary forest

Lianas are an important structural component of tropical rain forests. Recent concern regarding a putative global rise in liana abundance, and its implications for forest conservation, calls for data collection across biomes. We here provide a first assessment and baseline data for a geographical gap in liana surveys to date. We surveyed liana (diameter at breast height [DBH] > 1 cm), tree (DBH > 10 cm) and sapling (DBH ≤ 10 cm) abundance and basal area, as well as liana–host relationships, in a tropical East African primary forest. We recorded a total of 347 liana stems (DBH > 1 cm) in 0.31 ha, with an average basal area of 1.21 m²/ha. Lianas were found to be widespread, with 24% of saplings and 57% of trees colonised by at least one liana, independently of bark texture or host diameter. The dominant liana colonisation strategy was to associate with a single host, through stem twining. We found no evidence of liana density being influenced by host density. We synthesised published liana density data across continents and report that our estimate of liana density for Kibale's primary forest fits within the expected range of liana densities for primary tropical forests. This synthesis further highlights a neotropical sampling bias, which our findings make a step towards addressing.     

Detection of Coxiella burnetii specific DNA in blood samples from Japanese patients with chronic nonspecific symptoms by nested polymerase chain reaction

Sprague Dawley rats, previously infected with Phase-I Bordetella pertussis , developed more severe abnormal respiratory sounds than normal animals, but not coughing, when exposed to aerosolized capsaicin, one of several cough-inducing agents tested. Stethoscope examination suggested that greater production of pulmonary mucus might be occurring after capsaicin challenge of the infected animals, compared to the uninfected controls. Rats of three other strains gave characteristically different responses from the Sprague Dawleys. The administration of capsaicin to B. pertussis -infected rats may provide useful insights into the pathophysiology of excess mucus secretion in human pertussis.     

Synthesis and SAR of 1,3-thiazolyl thiophene and pyridine derivatives as potent, orally active and S1P₃-sparing S1P₁ agonists

We have previously disclosed 1,2,4-oxadiazole derivative 3 as a potent S1P(3)-sparing S1P(1) agonist. Although compound 3 exhibits potent and manageable immunosuppressive efficacy in various in vivo models, recent studies have revealed that its 1,2,4-oxadiazole ring is subjected to enterobacterial decomposition. As provisions for unpredictable issues, a series of alternative compounds were synthesized on the basis of compound 3. Extensive SAR studies led to the finding of 1,3-thiazole 24c with the EC(50) value of 3.4 nM for human S1P(1), and over 5800-fold selectivity against S1P(3). In rat on host versus graft reaction (HvGR), the ID(50) value of 24c was determined at 0.07 mg/kg. The pharmacokinetics in rat and monkey is also reported. Compared to compound 3, 24c showed excellent stability against enterobacteria.     

Identification and Determination of Selenoneine, 2-Selenyl-N α , N α , N α -Trimethyl-l-Histidine, as the Major Organic Selenium in Blood Cells in a Fish-Eating Population on Remote Japanese Islands

Selenoneine is the major selenium compound in fish muscles, and fish appears to be an important source of selenium in the fish-eating population. Selenoneine has strong antioxidant activity and a detoxifying function against methylmercury (MeHg) toxicity. Dietary intake, bioaccumulation, and metabolism of selenoneine have not been characterized in humans. A nutritional survey was conducted in remote islands of the Kagoshima Prefecture in Japan. To evaluate the potential risks and benefits of fish consumption for health, we measured concentrations of selenoneine, total selenium, MeHg, inorganic mercury, and polyunsaturated fatty acid (LC-PUFA) in the blood of a fish-eating human population. The erythrocyte, leukocyte, and platelet residues following removal of serum (cellular fraction) contained 0.510 μg Se/g, 0.212 μg selenoneine Se/g, and 0.262 μg Se-containing proteins Se/g, whereas the serum contained 0.174 μg total Se/g. Selenoneine was highly concentrated in the cellular fraction in a manner that was dependent on subjects' frequency of fish consumption. Concentrations of selenoneine were closely correlated with concentrations of MeHg in the cellular fraction. Selenoneine is the major chemical form of selenium in the blood cells of this fish-eating human population and may be an important biomarker for selenium redox status.     

Site-directed disulfide cross-linking shows that cleft flexibility in the periplasmic domain is needed for the multidrug efflux pump AcrB of Escherichia coli

Escherichia coli AcrB is a multidrug efflux transporter that recognizes multiple toxic chemicals having diverse structures. Recent crystallographic studies of the asymmetric trimer of AcrB suggest that each protomer in the trimeric assembly goes through a cycle of conformational changes during drug export. However, biochemical evidence for these conformational changes has not been provided previously. In this study, we took advantage of the observation that the external large cleft in the periplasmic domain of AcrB appears to become closed in the crystal structure of one of the three protomers, and we carried out in vivo cross-linking between cysteine residues introduced by site-directed mutagenesis on both sides of the cleft, as well as at the interface between the periplasmic domains of the AcrB trimer. Double-cysteine mutants with mutations in the cleft or the interface were inactive. The possibility that this was due to the formation of disulfide bonds was suggested by the restoration of transport activity of the cleft mutants in a dsbA strain, which had diminished activity to form disulfide bonds in the periplasm. Furthermore, rapidly reacting, sulfhydryl-specific chemical cross-linkers, methanethiosulfonates, inactivated the AcrB transporter with double-cysteine residues in the cleft expressed in dsbA cells, and this inactivation could be observed within a few seconds after the addition of a cross-linker in real time by increased ethidium influx into the cells. These observations indicate that conformational changes, including the closure of the external cleft in the periplasmic domain, are required for drug transport by AcrB.     

The development and evolution of bristle patterns in Diptera

The spatial distribution of sensory bristles on the notum of different species of Diptera is compared. Species displaying ancestral features have a simple organization of randomly distributed, but uniformly spaced, bristles, whereas species thought to be more derived bear patterns in which the bristles are aligned into longitudinal rows. The number of rows of large bristles on the scutum was probably restricted to four early on in the evolution of cyclorraphous Brachyceran flies. Most species have stereotyped patterns based on modifications of these four rows. The possible constraints placed upon the patterning mechanisms due to growth and moulting within the Diptera are discussed, as well as within hemimetabolous insects. The holometabolic life cycle and the setting aside of groups of imaginal cells whose function is not required during the growth period, may have provided the freedom necessary for the evolution of elaborate bristle patterns. We briefly review the current state of knowledge concerning the complex genetic pathways regulating achaete-scute gene expression and bristle pattern in Drosophila melanogaster, and consider mechanisms for the genetic regulation of the bristle patterns of other species of Diptera.     

Regulation of melanin-concentrating hormone receptor 1 signaling by RGS8 with the receptor third intracellular loop

Melanin-concentrating hormone (MCH) receptor 1 (MCH1R) belongs to the class A G protein-coupled receptors (GPCRs). The MCH-MCH1R system plays a central role in energy metabolism, and thus the regulation of signaling pathways activated by this receptor is of particular interest. Regulator of G protein signaling (RGS) proteins work by increasing the GTPase activity of G protein alpha subunits and attenuate cellular responses coupled with G proteins. Recent evidence has shown that RGS proteins are not simple G protein regulators but equally inhibit the signaling from various GPCRs. Here, we demonstrate that RGS8, which is highly expressed in the brain, functions as a negative modulator of MCH1R signaling. By using biochemical approaches, RGS8 was found to selectively and directly bind to the third intracellular (i3) loop of MCH1R in vitro. When expressed in HEK293T cells, RGS8 and MCH1R colocalized to the plasma membrane and RGS8 potently inhibited the calcium mobilization induced by MCH. The N-terminal 9 amino acids of RGS8 were required for the optimal capacity to downregulate the receptor signaling. Furthermore, Arg(253) and Arg(256) at the distal end of the i3 loop were found to comprise a structurally important site for the functional interaction with RGS8, since coexpression of RGS8 with R253Q/R256Q mutant receptors resulted in a loss of induction of MCH-stimulated calcium mobilization. This functional association suggests that RGS8 may represent a new therapeutic target for the development of novel pharmaceutical agents.     

Characterization of Functional Primary Cilia in Human Induced Pluripotent Stem Cell-Derived Neurons

Neurochemical Research - Recent advances in human induced pluripotent stem cells (hiPSCs) offer new possibilities for biomedical research and clinical applications. Neurons differentiated from...     

A role for macrophages in suppressor cell induction

A mechanism responsible for the induction of NP-specific first order (inducer) suppressor cells (TS1) is described. TS1 cells are induced by i.v. administration of hapten-coupled splenic cells. Their activity is assessed by the adoptive transfer of NP-specific suppression during the afferent phase of the contact sensitivity response. NP-coupled firmly adherent, FcR+, I-A-bearing macrophages induce TS1. The antigen-presenting cells required for TS1 induction lack the Thy-1 and Lyt-1 markers, and are resistant to 500 R irradiation and to cyclophosphamide treatment. NP-coupled dendritic cells fail to induce TS1 activity. The induction of TS1 cells is genetically restricted by genes that map in the I-J region of the H-2 complex. The NP-coupled antigen-presenting cells must share at least one I-J allele with the TS1 donor for effective induction of TS1 activity. To minimize allogeneic effects in these studies, the activity of the TS1 population was assessed by adoptive transfer into syngeneic recipients. The present results are compared with the mechanisms required for the induction of second and third order suppressor cells.