The economically important necrotrophic fungal pathogen, Pyrenophora tritici-repentis (Ptr), causes tan spot of wheat, a disease typified by foliar necrosis and chlorosis. The culture filtrate of an Australian Ptr isolate, M4, possesses phytotoxic activity and plant bioassay guided discovery led to the purification of necrosis inducing toxins called triticone A and B. High-resolution LC–MS/MS analysis of the culture filtrate identified an additional 37 triticone-like compounds. The biosynthetic gene cluster responsible for triticone production (the Ttc cluster) was identified and deletion of TtcA, a hybrid polyketide synthase (PKS)-nonribosomal peptide synthase (NRPS), abolished production of all triticones. The pathogenicity of mutant (ttcA) strains was not visibly affected in our assays. We hypothesize that triticones possess general antimicrobial activity important for competition in multi-microbial environments. 相似文献
Drosophila heart tube is a feasible model for cardiac physiological research. However, obtaining Drosophila electrocardiograms (ECGs) is difficult, due to the weak signals and limited contact area to apply electrodes. This paper presents a non-invasive Gallium-Indium (GaIn) based recording system for Drosophila ECG measurement, providing the heart rate and heartbeat features to be observed. This novel, high-signal-quality system prolongs the recording time of insect ECGs, and provides a feasible platform for research on the molecular mechanisms involved in cardiovascular diseases.
Methods
In this study, two types of electrode, tungsten needle probes and GaIn electrodes, were used respectively to noiselessly conduct invasive and noninvasive ECG recordings of Drosophila. To further analyze electrode properties, circuit models were established and simulated. By using electromagnetic shielded heart signal acquiring system, consisted of analog amplification and digital filtering, the ECG signals of three phenotypes that have different heart functions were recorded without dissection.
Results and Discussion
The ECG waveforms of different phenotypes of Drosophila recorded invasively and repeatedly with n value (n>5) performed obvious difference in heart rate. In long period ECG recordings, non-invasive method implemented by GaIn electrodes acts relatively stable in both amplitude and period. To analyze GaIn electrode, the correctness of GaIn electrode model established by this paper was validated, presenting accuracy, stability, and reliability.
Conclusions
Noninvasive ECG recording by GaIn electrodes was presented for recording Drosophila pupae ECG signals within a limited contact area and signal strength. Thus, the observation of ECG changes in normal and SERCA-depleted Drosophila over an extended period is feasible. This method prolongs insect survival time while conserving major ECG features, and provides a platform for electrophysiological signal research on the molecular mechanism involved in cardiac arrhythmia, as well as research related to drug screening and development. 相似文献
Latency-associated peptide (LAP) - expressing regulatory T cells (Tregs) are important for immunological self-tolerance and immune homeostasis. In order to investigate the role of LAP in human CD4+Foxp3+ Tregs, we designed a cross-sectional study that involved 42 colorectal cancer (CRC) patients. The phenotypes, cytokine-release patterns, and suppressive ability of Tregs isolated from peripheral blood and tumor tissues were analyzed. We found that the population of LAP-positive CD4+Foxp3+ Tregs significantly increased in peripheral blood and cancer tissues of CRC patients as compared to that in the peripheral blood and tissues of healthy subjects. Both LAP+ and LAP− Tregs had a similar effector/memory phenotype. However, LAP+ Tregs expressed more effector molecules, including tumor necrosis factor receptor II, granzyme B, perforin, Ki67, and CCR5, than their LAP− negative counterparts. The in vitro immunosuppressive activity of LAP+ Tregs, exerted via a transforming growth factor-β–mediated mechanism, was more potent than that of LAP− Tregs. Furthermore, the enrichment of LAP+ Treg population in peripheral blood mononuclear cells (PBMCs) of CRC patients correlated with cancer metastases. In conclusion, we found that LAP+ Foxp3+ CD4+ Treg cells represented an activated subgroup of Tregs having more potent regulatory activity in CRC patients. The increased frequency of LAP+ Tregs in PBMCs of CRC patients suggests their potential role in controlling immune response to cancer and presents LAP as a marker of tumor-specific Tregs in CRC patients. 相似文献
Insulin controls glucose homeostasis and lipid metabolism, and insulin impairment plays a critical role in the pathogenesis of diabetes mellitus. Human skeletal muscle and kidney enriched inositol polyphosphate phosphatase (SKIP) is a member of the phosphatidylinositol 3,4,5-trisphosphate phosphatase family (T. Ijuin et al. J. Biol. Chem. 275:10870-10875, 2000; T. Ijuin and T. Takenawa, Mol. Cell. Biol. 23:1209-1220, 2003). Previous studies showed that SKIP negatively regulates insulin-induced phosphatidylinositol 3-kinase signaling (Ijuin and Takenawa, Mol. Cell. Biol. 23:1209-1220, 2003). We now have generated mice with a targeted mutation of the mouse ortholog of the human SKIP gene, Pps. Adult heterozygous Pps mutant mice show increased insulin sensitivity and reduced diet-induced obesity with increased Akt/protein kinase B (PKB) phosphorylation in skeletal muscle but not in adipose tissue. The insulin-induced uptake of 2-deoxyglucose into the isolated soleus muscle was significantly enhanced in Pps mutant mice. A hyperinsulinemic-euglycemic clamp study also revealed a significant increase in the rate of systemic glucose disposal in Pps mutant mice without any abnormalities in hepatic glucose production. Furthermore, in vitro knockdown studies in L6 myoblast cells revealed that reduction of SKIP expression level increased insulin-stimulated Akt/PKB phosphorylation and 2-deoxyglucose uptake. These results imply that SKIP regulates insulin signaling in skeletal muscle. Thus, SKIP may be a promising pharmacologic target for the treatment of insulin resistance and diabetes. 相似文献
The natural habitat of Pinus torreyana, the Torrey pine, is restricted to two locales in coastal Southern California that experience substantial fog and low clouds during the dry months of a Mediterranean climate. In similar semi-arid climate systems that encounter fog or low clouds, many plants can capture atmospheric moisture and are capable of direct foliar water uptake to reduce water stress. In this study, we investigated if the needles of P. torreyana are also capable of direct water uptake. In addition to water immersion, we measured the surface properties along a needle using microdroplets. The droplet contact angle is a measure of surface wettability, and the droplet absorption is a measure of localized foliar water uptake. The results showed that the entire length of the P. torreyana needle, including under the base sheath, is hydrophilic and capable of direct water uptake. The spatial gradients of the wettability and the water uptake along the needle are relatively small. Moreover, the wettability and water uptake increase from young shoots to one-year and two-year old needles. Our results also showed that the decrease in water uptake at higher contact angles can be described by a linear regression. Compared with the leaves of four shrubs in the same habitat, Heteromeles arbutifolia, Malosma laurina, Rhus integrifolia, and Eriodictyon crassifolium, the P. torreyana needles have lower contact angles and higher water uptake rates.