IKVAV regulates ERK1/2 and Akt signalling pathways in BMMSC population growth and proliferation

Objectives

The molecular mechanism of bone marrow mesenchymal stem cell (BMMSC) population growth and proliferation, induced by Isoleucyl‐lysyl‐valyl‐alanyl‐valine (IKVAV), was explored in this study.

Materials and methods

IKVAV peptides were synthesized by the solid‐phase method. Influence of IKVAV on BMMSC population growth and proliferation were investigated by assays of CCK‐8, flow cytometry, real‐time PCR and western blotting.

Results

IKVAV peptide was found to induce proliferation and proliferating cell nuclear antigen (PCNA) synthesis of BMMSC in a dose‐ and time‐dependent manner. Cell cycle analysis showed that the proportion of IKVAV‐treated BMMSC in S phase in was higher than controls. Western blot results suggested that mitogen‐activated protein kinase/extracellular signal‐regulated kinase (MAPK/ERK) and phosphatidylinositol 3‐kinase/protein kinase B (PI3K/Akt) signalling pathways were activated by IKVAV by enhancing phosphorylation levels of ERK1/2 and Akt in the BMMSCs. Meanwhile, phosphorylation levels of ERK1/2 and Akt were partially blocked by ERK1/2 inhibitor (PD98059) and Akt inhibitor (wortmannin), respectively.

Conclusions

Our results demonstrated that IKVAV stimulated BMMSC population growth and proliferation by activating MAPK/ERK1/2 and PI3K/Akt signalling pathways. This study is the first to reveal an enhancement effect of IKVAV peptide on BMMSC at the signal transduction level, and the outcome could provide experimental evidence for application of IKVAV‐grafted scaffolds in the field of BMMSC‐based tissue engineering.

Structure and expression of a cysteine proteinase gene from Spodoptera litura and its response to biocontrol fungus Nomuraea rileyi

Cysteine proteinases (Cyps) play vital roles in many biological processes, including physiological and pathological reactions. In the present study, we cloned a full cDNA of SlCyp, encoding a 344-amino-acid protein from Spodoptera litura. The putative amino acid sequence shared >75% identity with Cyps from other insects. A phylogenetic analysis revealed that SlCyp is closely related to other known lepidopteran Cyps. Real-time PCR and Western blotting analyses showed that SlCyp is induced by Nomuraea rileyi infection in all the tissues tested. The strongest SlCyp mRNA and protein expression was found in haemocytes, followed by the fat bodies, of unchallenged and N. rileyi-challenged S. litura. A time-course analysis showed that SlCyp mRNA and protein expression levels were upregulated in the haemocytes and fat bodies by N. rileyi infection. Upon N. rileyi infection, the proteolytic activities of SlCyp were also significantly higher in the haemolymph than in normal or phosphate-buffered-saline-challenged controls. These results suggest that SlCyp plays an important role in the innate immunity of S. litura in response to N. rileyi. SlCyp mRNA and protein expression and activities were also elevated during sixth-instar moulting and metamorphosis. Knocking down SlCyp transcripts with double-stranded RNA interference caused prepupal, pupal, and adult phenotypic changes, and SlCyp-silenced mutant larvae displayed a significantly lower survival rate after N. rileyi infection. These facts suggest that SlCyp plays a significant role in resisting N. rileyi infection and an essential role in larval development. Our data should facilitate the development of techniques for S. litura control.

Electron density compression and oscillating effects on laser energy absorption in overdense plasma targets

An analytical model for energy absorption during the interaction of an ultrashort, ultraintense laser with an overdense plasma is proposed. Both the compression effect of the electron density profile and the oscillation of the electron plasma surface are self-consistently included, which exhibit significant influences on the laser energy absorption. Based on our model, the general scaling law of the compression effect depending on laser strength and initial density is derived, and the temporal variation of the laser absorption due to the boundary oscillating effect is presented. It is found that due to the oscillation of the electron plasma surface, the laser absorption rate will vibrate periodically at ω or 2ω frequency for the p-polarized and s-polarized laser, respectively. The effect of plasma collision on the laser absorption has also been investigated, which shows a considerable rise in absorption with increasing electron-ion collision frequency for both polarizations.

Response of the annual biomass production of a typical steppe plant community to precipitation fluctuations

Understanding the relationship between the aboveground net primary production (ANPP) and annual precipitation in arid and semiarid grasslands is crucial for assessing the effects of climate change on grassland ecosystems. The temporal pattern of ANPP, based on long-term data on a semiarid ecosystem in Inner Mongolia, was investigated. The biomass of perennial grasses, perennial forbs and Stipa grandis P. Smirn., showed a positive relationship with annual precipitation. The amount of annual precipitation also changed the annual biomass of 13 other dominant species and consequently the ANPP. The coefficient of variation of the ANPP of the plant community was lower than the coefficient of variation of annual precipitation. Irrespective of the strong inter-annual variation in annual precipitation, the positive relationship found between ANPP and annual precipitation suggests the dependence of ANPP upon hydrological variations in typical steppe. Our findings highlight the importance of dominant perennial species and functional groups in mediating the responses of ANPP to annual precipitation in the typical steppe in northern China.

Herders’ perception of climate change does not always fit with actual climate change

Herders’ perceptions are important in relation to adopting adaptive behavioural approaches to climate change. A survey of 1080 herder households was conducted in six rangeland regions of Inner Mongolia in northern China to investigate relationships between herder’s perceptions and actual climate change. Across all six regions, more than 90% of herders perceived a decline in precipitation in the past 30 years, whereas actual data showed no significant change. Many herders also perceived an increase in temperature, which was in agreement with the temperature data, although the proportion of herders who perceived a change in temperature differed among regions. A further survey of 58 households was conducted to better understand the reasons for these differences, by simultaneously surveying their perceptions of the changes in both rainfall and rangeland condition. The results showed that the herders’ perceptions of a decrease in rainfall could be influenced by their perceptions of the changes in the condition of their rangeland (reductions in production). An alternative explanation could relate to rainfall being interpreted in terms of the frequency and pattern rather than the absolute amounts. These findings have important implications for understanding how herders’ perceptions can improve their adaptive behavioural responses to climate change.

Controlling the hydrothermal growth and the properties of ZnO nanorod arrays by pre-treating the seed layer

Annealing or plasma pre-treating the ZnO seed layer influences the nucleation and hydrothermal growth of ZnO nanorods and their photoluminescence.

Birth oxidative stress and the development of an antioxidant system in newborn piglets

Birth oxidative stress is an oxidative response to a sudden transition process from maternal mediated respiration in uterus to autonomous pulmonary respiration outside the uterus. Meanwhile, oxidative stress has been demonstrated to be associated with various pathologies recorded in newborns. So, this research aimed to study the oxidative stress and the development of antioxidant system in newborn piglets. The measured variables include plasma lipid, protein and DNA oxidant injury, the activities of plasma antioxidant enzymes and the jejunal and ileal antioxidant gene expressions at 1, 7, 14, and 21 days after birth. Meanwhile, the nuclear factor erythroid 2-related factor 2 (Nrf2), transcription factor p65, and tumor protein 53 (p53) were determined by western blot. The results showed that newborn piglets suffered seriously from birth oxidative stress because of the naive antioxidant system. In addition, oxidant injury activated Nrf2 signaling pathway, resulting in the expression of antioxidant genes and release of antioxidant enzymes. With the development of antioxidant system, the oxidative balance gradually recovered on Day 7 after birth. In conclusion, birth caused oxidative stress and the oxidative balance gradually recovered with the development of antioxidant system.

Simultaneous generation of monoenergetic tunable protons and carbon ions from laser-driven nanofoils

Simultaneous generation of monoenergetic tunable protons and carbon ions from intense laser multi-component nanofoil interaction is demonstrated by using particle-in-cell simulations. It is shown that, the protons with the largest charge-to-mass ratio are instantly separated from other ion species and are efficiently accelerated in the "phase stable" way. The carbon ions always ride on the heavier oxygen ion front with an electron-filling gap between the protons and carbon ions. At the cost of widely spread oxygen ions, monoenergetic collimated protons and carbon ions are obtained simultaneously. By modulating the heavier ion densities in the foil, it is capable to control the final beam quality, which is well interpreted by a simple analytical model.

Coherent Josephson qubit suitable for scalable quantum integrated circuits

We demonstrate a planar, tunable superconducting qubit with energy relaxation times up to 44 μs. This is achieved by using a geometry designed to both minimize radiative loss and reduce coupling to materials-related defects. At these levels of coherence, we find a fine structure in the qubit energy lifetime as a function of frequency, indicating the presence of a sparse population of incoherent, weakly coupled two-level defects. We elucidate this defect physics by experimentally varying the geometry and by a model analysis. Our "Xmon" qubit combines facile fabrication, straightforward connectivity, fast control, and long coherence, opening a viable route to constructing a chip-based quantum computer.