Effects of grazing intensity on soil carbon stocks following deforestation of a Hawaiian dry tropical forest

The effects of forest-to-pasture conversion on soil carbon (C) stocks depend on a combination of climatic and management factors, but factors that relate to grazing intensity are perhaps the least understood. To understand the long-term impact of grazing in converted pastures, methods are needed that accurately measure the impact of grazing on recent plant inputs to soil C in a variety of pasture management and climate settings. Here, we present an analysis from Hawai'i of changes in vegetation structure and soil organic carbon (SOC) along gradients of grazing intensity and elevation in pastures converted from dry tropical forest 100 years ago. We used hyperspectral remote sensing of photosynthetic vegetation, nonphotosynthetic vegetation (NPV) and exposed substrate to understand the effects of grazing on plant litter cover, thus, estimating recent plant inputs to soils (the NPV component). Forest-to-pasture conversion caused a shift from C3 to C4 plant physiology, thus the δ ¹³C method was used in soil cores to measure the fraction of SOC accumulated from pasture vegetation sources following land conversion. SOC decreased in pasture by 5–9 kg C m⁻², depending upon grazing intensity. SOC derived from C3 (forest) sources was constant across the grazing gradient, indicating that the observed variation in SOC was attributable to changes in C inputs following deforestation. Soil C stocks were also reduced in pastures relative to forest soils. We found that long-term grazing lowers SOC following Hawaiian forest-to-pasture conversion, and that these changes are larger in magnitude that those occurring with elevation (climate). Further we demonstrate a relationship between remotely sensed measurements of surface litter and field SOC measurements, allowing for regional analysis of pasture condition and C storage where limited field data are available.     

Surface plasmon resonance imaging analysis of hexahistidine-tagged protein on the gold thin film coated with a calix crown derivative

A surface plasmon resonance (SPR) imaging system was constructed and used to detect the hexahistidine-ubiquitin-tagged human parathyroid hormone fragment (His₆-Ub-hPTHF(1–34)) expressed inEscherichia coli. The hexahistidine-specific antibody was immobilized on a thin gold film coated with ProLinker^TM B, a novel calixcrown derivative with a bifunctional coupling property that permits efficient immobilization of capture proteins on solid matrices. The soluble and insoluble fractions of anE. coli cell lysate were spotted onto the antibody-coated gold chip, which was then washed with buffer (pH 7.4) solution and dried. SPR imaging measurements were carried out to detect the expressed His₆-Ub-hPTHF (1–34). There was no discernible protein image in the uninduced cell lysate, indicating that non-specific binding of contaminant proteins did not occur on the gold chip surface. It is expected that the approach used here to detect affinity-tagged recombinant proteins using an SPR imaging technique could be used as a powerful tool for the analyses of a number of proteins in a high-throughput mode.     

Calmodulin modulates insect odorant receptor function

Insect odorant receptors (ORs) are heteromeric complexes of an odor-specific receptor protein (OrX) and a ubiquitous co-receptor protein (Orco). The ORs operate as non-selective cation channels, also conducting Ca²⁺ ions. The Orco protein contains a conserved putative calmodulin (CaM)-binding motif indicating a role of CaM in its function. Using Ca²⁺ imaging to monitor OR activity we investigated the effect of CaM inhibition on the function of OR proteins. Ca²⁺ responses elicited in Drosophila olfactory sensory neurons by stimulation with the synthetic OR agonist VUAA1 were reduced and prolonged by CaM inhibition with the potent antagonist W7 but not with the weak antagonist W5. A similar effect was observed for Orco proteins heterologously expressed in CHO cells when CaM was inhibited with W7, trifluoperazine or chlorpromazine, or upon overexpression of CaM-EF-hand mutants. With the Orco CaM mutant bearing a point mutation in the putative CaM site (K339N) the Ca²⁺ responses were akin to those obtained for wild type Orco in the presence of W7. There was no uniform effect of W7 on Ca²⁺ responses in CHO cells expressing complete ORs (Or22a/Orco, Or47a/Orco, Or33a/Orco, Or56a/Orco). For Or33a and Or47a we observed no significant effect of W7, while it caused a reduced response in cells expressing Or22a and a shortened response for Or56a.     

Rho‐kinase inhibitor Y‐27632 increases cellular proliferation and migration in human foreskin fibroblast cells

The idea of direct differentiation of somatic cells into other differentiated cell types has attracted a great interest recently. Rho‐kinase inhibitor Y‐27632 (ROCKi) is a potential drug molecule, which has been reported to support the gene expressions typical for the chondrocytes, thus restricting their phenotypic conversion to fibroblastic cells upon the cellular expansion. In this study, we have investigated the short‐term biological responses of ROCKi to human primary foreskin fibroblasts. The fibroblast cells were exposed to 1 and 10 μM ROCKi treatments. A proteomics analysis revealed expression changes of 56 proteins, and a further protein pathway analysis suggested their association with the cell morphology, the organization, and the increased cellular movement and the proliferation. These functional responses were confirmed by a Cell‐IQ time‐lapse imaging analysis. Rho‐kinase inhibitor treatment increased the cellular proliferation up to twofold during the first 12 h, and a wound model based migration assay showed 50% faster filling of the mechanically generated wound area. Additionally, significantly less vinculin‐associated focal adhesions were present in the ROCKi‐treated cells. Despite the marked changes in the cell behavior, ROCKi was not able to induce the expression of the chondrocyte‐specific genes, such as procollagen α₁(II) and aggrecan.     

空间独立成分分析实现fMRI信号的盲分离

独立成分分析（ICA）在功能核磁共振成像（fMRI)技术中的应用是近年来人们关注的一个热点。简要介绍了空间独立成分分析（SICA）的模型和方法,将fMRI信号分析看作是一种盲源分离问题,用快速算法实现fMRI信号的盲源分离。对fMRI信号的研究大多是在假定已知事件相关时间过程曲线的情况下,利用相关性分析得到脑的激活区域。在不清楚有哪几种因素对fMRI信号有贡献、也不清楚其时间过程曲线的情况下,用SICA可以对fMRI信号进行盲源分离,提取不同独立成分得到任务相关成分、头动成分、瞬时任务相关成分、噪声干扰、以及其它产生fMRI信号的多种源信号。     

Autofluorescence imaging for recurrence detection in skin cancer postoperative scars

This clinical study is a first attempt to use autofluorescence for recurrence diagnosis of skin cancer in postoperative scars. The proposed diagnostic parameter is based on a reduction in scar autofluorescence, evaluated in the green spectral channel. The validity of the method has been tested on 110 postoperative scars from 56 patients suspected of non‐melanoma skin cancer, with eight patients (13 scars) available for the repeated examination. The recurrence diagnosis within a scar has been made after two subsequent autofluorescence check‐ups, representing the temporal difference between the scar autofluorescence amplitudes as a vector. The recognition of recurrence has been discussed to represent the significant deviations from the value of vector angle θ. This new autofluorescence‐based method can be easily integrated into the postoperative monitoring of surgical scars and can help diagnose the recurrence of skin cancer from the early stage of scar development.     

Survival and death of epiblast cells during embryonic stem cell derivation revealed by long-term live-cell imaging with an Oct4 reporter system

Despite the broad literature on embryonic stem cells (ESCs), their derivation process remains enigmatic. This may be because of the lack of experimental systems that can monitor this prolonged cellular process. Here we applied a live-cell imaging technique to monitor the process of ESC derivation over 10 days from morula to outgrowth phase using an Oct4/eGFP reporter system. Our imaging reflects the ‘natural’ state of ESC derivation, as the ESCs established after the imaging were both competent in chimeric mice formation and germ-line transmission. Using this technique, ESC derivation in conventional conditions was imaged. After the blastocoel was formed, the intensity of Oct4 signals attenuated in the trophoblast cells but was maintained in the inner cell mass (ICM). Thereafter, the Oct4-positive cells scattered and their number decreased along with apoptosis of the other Oct4-nagative cells likely corresponds to trophoblast and hypoblast cells, and then only the surviving Oct4-positive cells proliferated and formed the colony. All embryos without exception passed through this cell death phase. Importantly, the addition of caspase inhibitor Z-VAD-FMK to the medium dramatically suppressed the loss of Oct4-positive cells and also other embryo-derived cells, suggesting that the cell deaths was induced by a caspase-dependent apoptotic pathway. Next we imaged the ESC derivation in 3i medium, which consists of chemical compounds that can suppress differentiation. The most significant difference between the conventional and 3i methods was that there was no obvious cell death in 3i, so that the colony formation was rapid and all of the Oct4-positive cells contributed to the formation of the outgrown colony. These data indicate that the prevention of cell death in epiblast cells is one of the important events for the successful establishment of ESCs. Thus, our imaging technique can advance the understanding of the time-dependent cellular changes during ESC derivation.     

Prevalence and predictors of bridging of coronary arteries in a large Indonesian population, as detected by 64-slice computed tomography scan

Background

Multislice computed tomography (MSCT) can be used to detect myocardial bridging (MB) of coronary arteries. However, most published studies included small cohorts and did not collect data about predictors. We investigated prevalence and predictors of MB in an Indonesian population.

Methods

All patients who had MSCT at Cinere Hospital, Jakarta, Indonesia between 2006 and 2009 were included in a prospective registry. MB was defined when at least half of the coronary artery was imbedded within the myocardium with a normal epicardial course of the proximal and distal portion.

Results

Of the 934 patients (mean age 53 years, 37.8 % female), MB could be observed in 152 patients (16.3 %). Patients with MB were younger compared with those without MB. Coronary risk factors were not different between the two groups. Coronary calcifications and moderate to severe coronary stenoses were less prevalent in patients with MB, also after adjusting for differences in age. At the time of diagnosis, only a few patients with MB were treated with beta-blockers (35 %) or calcium channel blockers (13 %).

Conclusions

Prevalence of myocardial bridging as detected by MSCT is relatively high. Patients with MB were younger and had a lower prevalence of coronary sclerosis. MB could be the cause of their unexplained symptoms. Follow-up studies are necessary to assess the symptoms of these patients, their response to treatment and the incidence of (coronary) events. MSCT can be used to identify patients for potential new treatment strategies.     

Assessment of Plasmodium falciparum PfMDR1 transport rates using Fluo‐4

Mutations in the multidrug resistance transporter of Plasmodium falciparum PfMDR1 have been implicated to play a significant role in the emergence of worldwide drug resistance, yet the molecular and biochemical mechanisms of this transporter are not well understood. Although it is generally accepted that drug resistance in P. falciparum is partly associated with PfMDR1 transport activity situated in the membrane of the digestive vacuole, direct estimates of the pump rate of this transport process in the natural environment of the intact host–parasite system have never been analysed. The fluorochrome Fluo‐4 is a well‐documented surrogate substrate of PfMDR1 and has been found to accumulate by actively being transported into the digestive vacuole of several parasitic strains. In the present study, we designed an approach to use Fluo‐4 fluorescence uptake as a measure of compartmental Fluo‐4 concentration accumulation in the different compartments of the host–parasite system. We performed a ‘reverse Fluo‐4 imaging' approach to relate fluorescence intensity to changes in dye concentration rather than Ca²⁺ fluctuations and were able to calculate the overall rate of transport for PfMDR1 in Dd2 parasites. With this assay, we provide a powerful method to selectively measure the effect of PfMDR1 mutations on substrate transport kinetics. This will be of high significance for future compound screening to test for new drugs in resistant P. falciparum strains.     

Investigation of an F-18 oxytocin receptor selective ligand via PET imaging

The compound 1-(1-(2-(2-(2-fluoroethoxy)-4-(piperidin-4-yloxy)phenyl)acetyl)piperidin-4-yl)-3,4-dihydroquinolin-2(1H)-one (1) was synthesized and positively evaluated in vitro for high potency and selectivity with human oxytocin receptors. The positron emitting analogue, [F-18]1, was synthesized and investigated in vivo via PET imaging using rat and cynomolgus monkey models. PET imaging studies in female Sprague–Dawley rats suggested [F-18]1 reached the brain and accumulated in various regions of the brain, but washed out too rapidly for adequate quantification and localization. In vivo PET imaging studies in a male cynomolgus monkey suggested [F-18]1 had limited brain penetration while specific uptake of radioactivity significantly accumulated within the vasculature of the cerebral ventricles in areas representative of the choroid plexus.