Strong and High-Precision Manipulation of Nanoparticle with Graphene-Coated Fiber Systems

Two kinds of graphene-coated fiber systems are proposed and studied for optical trapping. Their plasmonic modes in uniform environment and close to the substrate are studied in the finite element method. The optical forces exerted on dielectric nanoparticle by these systems are calculated by standalone waveguide approximation. It is found that for the dielectric particle with diameter of 1 nm, the maximal optical forces generated by certain modes are more than 10⁷ fN/W whereas their force ranges are only one to several nanometers. These results may have important applications in strong and high-precision optical tweezers.

     

Subpopulation genetic structure of a plant panmictic population of Castanea sequinii as revealed by microsatellite markers

Castanea squinii Dode, an endemic tree widely distributed in China, plays an important role both in chestnut breeding and forest ecosystem function. The spatial genetic structure within and among populations is an important part of the evolutionary and ecological genetic dynamics of natural populations, and can provide insights into effective conservation of genetic resources. In the present study, the spatial genetic structure of a panmictic natural population of C. sequinii in the Dabie Mountain region was investigated using microsatellite markers. Nine prescreened microsatellite loci generated 29–33 alleles each, and were used for spatial autocorrelation analysis. Based on Moran’s I coefficient, a panmictic population of C. sequinii in the Dabie Mountain region was found to be lacking a spatial genetic structure. These results suggest that a high pollen-mediated gene flow among subpopulations counteract genetic drift and/or genetic differentiation and plays an important role in maintaining a random and panmictic population structure in C. sequinii populations. Further, a spatial genetic structure was detected in each subpopulation’s scale (0.228 km), with all three subpopulations showing significant fine-scale structure. The genetic variation was found to be nonrandomly distributed within 61 m in each subpopulation (Moran’s I positive values). Although Moran’s I values varied among the different subpopulations, Moran’s I in all the three subpopulations reached the expected values with an increase in distances, suggesting a generally patchy distribution in the subpopulations. The fine-scale structure seems to reflect restricted seed dispersal and microenvironment selection in C. sequinii. These results have important implications for understanding the evolutionary history and ecological process of the natural population of C. sequinii and provide baseline data for formulating a conservation strategy of Castanea species. __________ Translated from Acta Phytoecologica Sinica, 2006, 30(1): 147–156 [译自: 植物生态学报]     

An approach to identify cold-induced low-abundant proteins in rice leaf

A proteomic approach has been adopted to investigate the low-abundant proteins in rice leaf in response to cold stress. Rice seedlings were exposed to different temperatures, such as 5 or 10 degrees C, and samples were collected after different time course. To eliminate the high-abundant proteins in leaf tissues such as ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), proteins were fractionated by polyethylene glycol (PEG). The elimination of Rubisco from the protein samples was confirmed by Western blot analysis. The PEG fractionated protein samples were separated by 2-DE and visualized by silver or CBB staining. A total 12 up-regulated protein spots were identified using the analysis of MALDI-TOF mass spectrometry or ESI MS/MS. We identified some novel proteins such as cysteine proteinase, thioredoxin peroxidase, a RING zinc finger protein-like, drought-inducible late embryogenesis abundant, and a fibrillin-like protein that had not yet been reported in the earlier reports on cold proteomic analysis. The identification of some novel low-abundant proteins in response to cold stress may provide a new homeostasis to develop enhanced cold tolerance transgenic plants. Thus, we propose that a PEG fractionation system can be used as an influential protein extraction method from the leaf samples, which can lead to knowledge of the expression pattern of low-abundant proteins in response to various biotic or abiotic stresses.     

Inactivation of the Hansenula polymorpha PMR1 gene affects cell viability and functioning of the secretory pathway

In yeast, functions of the endoplasmic reticulum (ER) depend on the Golgi apparatus Ca2+ pool, which is replenished by the medial-Golgi ion pump Pmr1p. Here, to dissect the role of the Golgi Ca2+ pool in protein folding and elimination of unfolded proteins in the ER, the manifestations of the pmr1 mutation in yeast Hansenula polymorpha were studied. The PMR1 gene was disrupted in a H. polymorpha diploid strain. Haploid segregants of this diploid bearing the disruption allele were viable, though they showed a severe growth defect on synthetic medium and rapidly died during storage at low temperature. Disruption of H. polymorpha PMR1 led to defects of the Golgi-hosted protein glycosylation and vacuolar protein sorting. This mutation increased the survival rate of H. polymorpha cells upon treatment with the proapoptotic drug amiodarone. Unlike Saccharomyces cerevisiae, the H. polymorpha pmr1 mutant was not hypersensitive to chemicals that induce the accumulation of unfolded proteins in the ER, indicating that the elimination of unfolded proteins from the ER was not essentially affected. At the same time, the pmr1 mutation improved the secretion of human urokinase and decreased its intracellular aggregation, indicating an influence of the mutation on the protein folding in the ER.     

Downregulation of lysyl oxidase-like 4 LOXL4 by miR-135a-5p promotes lung cancer progression in vitro and in vivo

Aberrant microRNAs are widely identified in multiple cancers, including lung cancer. miR-135a-5p can function as a significant tumor regulator in diverse cancers via impacting multiple genes in oncogenic pathways. Nevertheless, the biological role of miR-135a-5p in lung cancer is poorly known. Here, we investigated its function in lung cancer. As exhibited, miR-135a-5p was elevated in lung cancer cells in contrast to BEAS-2B cells. Then, we inhibited miR-135a-5p expression by transfecting LV-anti-miR-135a-5p into lung cancer cells. As displayed, miR-135a-5p was obviously reduced in A549 and H1299 cells. Knockdown of miR-135a-5p repressed lung cancer cell growth and cell proliferation. Meanwhile, cell colony formation capacity was depressed, cell apoptosis was enhanced and cell cycle progression was blocked in G1 phase by inhibition of miR-135a-5p in vitro. Additionally, the migration and invasion of A549 and H1299 cells was strongly depressed by LV-anti-miR-135a-5p. For another, by using informatics analysis, lysyl oxidase-like 4 (LOXL4) was speculated as the downstream target of miR-135a-5p. We validated their direct correlation and moreover, overexpression of miR-135a-5p restrained LOXL4 levels in lung cancer cells. Subsequently, we proved that miR-135a-5p promoted lung cancer development via targeting LOXL4 by carrying out the in vivo assays. Taken these together, our study revealed miR-135a-5p might be indicated as a perspective for lung cancer via targeting LOXL4.