Large gradient high magnetic field affects the association of MACF1 with actin and microtubule cytoskeleton

The intense inhomogeneous magnetic fields acting on the diamagnetic materials naturally present in cells can generate strong magnetic forces. We have developed a superconducting magnet platform with large gradient high magnetic field (LG‐HMF), which can produce three magnetic force fields of ?1360, 0, and 1312 T²/m, and three corresponding apparent gravity levels, namely 0, 1, and 2‐g for diamagnetic materials. In this study, the effects of different magnetic force fields on osteoblast‐like cells (MG‐63 and MC3T3‐E1) viability, microtubule actin crosslinking factor 1 (MACF1) expression and its association with cytoskeleton were investigated. Results showed that cell viability increased to different degrees after exposure to 0 or 1‐g conditions for 24 h, but it decreased by about 30% under 2‐g conditions compared with control conditions. An increase in MACF1 expression at the RNA or protein level was observed in osteoblast‐like cells under the magnetic force field of ?1360 T²/m (0‐g) relative to 1312 T²/m (2‐g). Under control conditions, anti‐MACF1 staining was scattered in the cytoplasm and partially colocalized with actin filaments (AFs) or microtubules (MTs) in the majority of osteoblast‐like cells. Under 0‐g conditions, MACF1 labeling was concentrated at perinuclear region and colocalization was not apparent. The patterns of anti‐MACF1 labeling on MTs varied with MTs' changing under LG‐HMF environment. In conclusion, LG‐HMF affects osteoblast‐like cell viability, MACF1 distribution, expression, and its association with cytoskeleton to some extent. Bioelectromagnetics 30:545–555, 2009. © 2009 Wiley‐Liss, Inc.     

Effects of cutinase on the enzymatic shrink-resist finishing of wool fabrics

A novel microbial cutinase from Thermobifida fusca WSH04 was applied in the pretreatment of wool fabrics followed by protease treatment, aiming at improving the wettability of the samples by hydrolyzing the outmost bound lipids in the wool surface. Cutinase pretreatment could increase the efficacy of the subsequent protease treatment by improving the wettability, dyeability, and shrink-resistance of the wool fabrics. The data obtained by the XPS method showed the changes of elemental concentration in the wool surface after cutinase pretreatment. Compared with the fabrics treated with hydrogen peroxide and protease, the combination of cutinase and protease treatments produced better results in terms of wettability and shrink-resistance with less strength loss. The anti-felting property of the fabrics treated with the enzymatic resist-shrink technique is very promising to meet the commercial standard.     

果蝇变态过程中的细胞凋亡和细胞自噬

程序化细胞死亡(programmed cell death,PCD)分为I型PCD细胞凋亡(apoptosis)和II型PCD细胞自噬(autophagy)。果蝇等完全变态昆虫有2种类型的器官:即细胞内分裂器官(如脂肪体、表皮、唾液腺、中肠、马氏管等)和有丝分裂器官(复眼、翅膀、足、神经系统等)。在昆虫变态过程中,细胞内分裂器官进行器官重建,幼虫器官大量发生细胞凋亡和细胞自噬到最后完全消亡,同时成虫器官由干细胞从新生成;而有丝分裂器官则由幼虫器官直接发育为成虫器官。在果蝇等昆虫的变态过程中,细胞凋亡和细胞自噬在幼虫器官的死亡和成虫器官的生成中发挥了非常重要的作用。文章简要介绍细胞凋亡和细胞自噬在果蝇变态过程中的生理功能和分子调控机制。     

Reproductive traits associated with invasiveness in Conyza sumatrensis

Conyza sumatrensis (Retz.) E. Walker, a member of Asteraceae, is a highly invasive species. However, its reproduction biology remains poorly known. To understand the role of reproductive traits in successful invasion of the species, we studied several traits of its reproductive system: the miniature capitulum and gynomonoecious sexual system, the biology and phenology of capitula and florets, pollen/ovule ratio, the mating system (selfcompatibility), flower visitors, physical traits and dispersal potential of achenes, germination potential of achenes from manually pollinated capitula, and the association of these traits with invasiveness. Our study showed that the reproductive traits of autonomous seed production, versatile mating system of self- and cross-pollination, and generalized pollination system might contribute to the species' successful invasive capability. The invasiveness was further enhanced by the high and rapid production of achenes, as well as the high percentage, rapid germination rate and high dispersal capability of achenes. It was concluded that in annual or winter-annual weeds, autonomous seed production contributed significantly to the invasiveness of the species.     

Doxycycline enhances the Ras‐MAPK signaling and proliferation of mouse thymic epithelial cells

Depletion of T‐cell‐dependent immunity is a major consideration for patients suffering from infections of human immunodeficiency virus (HIV), those undergoing organ transplantation, and those receiving anti‐cancer chemotherapy and/or radiotherapy. In general, T‐cell regeneration occurs in the thymus through thymopoiesis. We have found that doxycycline (Dox), a tetracycline derivative, enhances the proliferation of mouse thymic epithelial cells, which are unique in their capacity to support positive selection and are essential throughout the development of thymocytes. Cell cycle analysis indicates that the increased cell proliferation is due to a shortened G₀/G₁ phase. To reveal the underlying mechanisms, we examined the expression of an array of molecules that regulate the cell cycle. The results show that in mouse thymic medullary‐type epithelial cell line 1 (MTEC1) Dox leads to elevated levels of H‐Ras, phosphorylated extracellular signal‐regulated kinase 1/2 (p‐ERK1/2), cyclin E, cyclin dependent kinase 4/2 (CDK4/CDK2), E2F3, and c‐myc. These data, and the observation that the proliferation‐enhancing effect is largely abolished following treatment with an ERK inhibitor support an active role of the Ras‐ERK/mitogen‐activated protein kinase (MAPK) signaling pathway. In conclusion, the present study reveals a new activity of an old family of antibiotics. The in vivo effect of Dox on immune reconstitution warrants further exploration. J. Cell. Biochem. 107: 494–503, 2009. © 2009 Wiley‐Liss, Inc.     

In vitro labeling of human umbilical cord mesenchymal stem cells with superparamagnetic iron oxide nanoparticles

Human umbilical cord mesenchymal stem cells (hUC‐MSCs) transplantation has been shown to promote regeneration and neuroprotection in central nervous system (CNS) injuries and neurodegenerative diseases. To develop this approach into a clinical setting it is important to be able to follow the fates of transplanted cells by noninvasive imaging. Neural precursor cells and hematopoietic stem cells can be efficiently labeled by superparamagnetic iron oxide (SPIO) nanoparticle. The purpose of our study was to prospectively evaluate the influence of SPIO on hUC‐MSCs and the feasibility of tracking for hUC‐MSCs by noninvasive imaging. In vitro studies demonstrated that magnetic resonance imaging (MRI) can efficiently detect low numbers of SPIO‐labeled hUC‐MSCs and that the intensity of the signal was proportional to the number of labeled cells. After transplantation into focal areas in adult rat spinal cord transplanted SPIO‐labeled hUC‐MSCs produced a hypointense signal using T2‐weighted MRI in rats that persisted for up to 2 weeks. This study demonstrated the feasibility of noninvasive imaging of transplanted hUC‐MSCs. J. Cell. Biochem. 108: 529–535, 2009. © 2009 Wiley‐Liss, Inc.     

Hydroxylation of thiacloprid by bacterium Stenotrophomonas maltophilia CGMCC1.1788

Chloropyridinyl neonicotinoid insecticides play a major role in crop protection and flea control on cats and dogs. Imidacloprid, thiacloprid and acetamiprid have in common the 6-chloro-3-pyridinylmethyl group but differ in the nitroguanidine or cyanoamidine substituent on an acyclic or cyclic moiety. Our previous study found that Stenotrophomonas maltophilia CGMCC 1.1788 could hydroxylate imidacloprid to 5-hydroxy imidacloprid, and 5-hydroxy imidacloprid was easily converted to 10–19 times higher insecticidal olefin imidacloprid against aphid or whitefly. Acetamiprid could be transformed by S. maltophilia to form N-demethylation product(IM 2-1). In this paper, we examined S. maltophilia CGMCC 1.1788’s ability of transformation of thiacloprid. S. maltophilia CGMCC 1.1788 can hydroxylate thiacloprid to 4-hydroxy thiacloprid characterized by HPLC-MS/MS and NMR analysis, however 4-hydroxy thiacloprid could not be converted to olefin thiacloprid under acid conditions like imidacloprid, whereas oxidized and decyonated simultaneously to form 4-ketone thiacloprid imine in alkaline solution. Bioassays indicated that 4-hydroxy thiacloprid had 156 times lower insecticidal activity than thiacloprid, and the ketone-imine derivative almost had no toxicity towards aphid. Though both imidacloprid and thiacloprid are hydroxylated by S. maltophilia CGMCC 1.1788 at the same carbon atom position, however the structural difference between in imidacloprid and thiacloprid, originate the entire discrepancy in bioefficacy of metabolite and its further degrading pathway. These results explain that why thiacloprid is classified as not relevant grade for soil and seed applications, whereas imidacloprid is recommended and acetamiprid is limited.     

Nitrogen transformations in vertical flow systems with and without rice (Oryza sativa) studied with a high-resolution soil–water profiler

Nitrogen transformations were studied in flooded and non-flooded vertical flow columns with and without a rice plant. Influent (average concentration: NH₄⁺-N: 40 mg L^?1; NO₃^?-N: 0.15 mg L^?1; and NO₂^?-N: 4.0 mg L^?1) was supplied at 1.25 cm d^?1 during stage 1 (20 May–5 August) and at 2.50 cm d^?1 at stage 2 (6 August–26 October), which resulted in an average nitrogen loading of 156 g m^?2 during the entire experimental period. Total nitrogen (T-N) removal efficiencies exceeded 90% in vertical flow systems with rice plants. Nitrogen assimilated by the rice plants in the flooded column accounted for 60% of the total input nitrogen, while that in the non-flooded column accounted for 36% of the total input. The remaining nitrogen appeared to be removed through biogeochemical pathways. Although some nitrogen flowed out, most input nitrogen was also removed even in the flooded and non-flooded unplanted columns.A high-resolution vertical distribution investigation showed the changes of nitrogen forms in soil water. In the flooded condition, there were high ammonium and high nitrite concentrations in the upper layers. The concentrations of ammonium and nitrite simultaneously decreased with depth increasing, suggesting that anaerobic ammonia oxidation (anammox) may occur in these anaerobic conditions. In contrast, the distributions of nitrogen in the non-flooded columns with elevated water level suggested that nitrification–denitrification route was the major removal mechanism, whether or not rice plants were present.