Genetic architecture of ecological divergence between Oryza rufipogon and Oryza nivara.

Ecological divergence due to habitat difference plays a prominent role in the formation of new species, but the genetic architecture during ecological speciation and the mechanism underlying phenotypic divergence remain less understood. Two wild ancestors of rice (Oryza rufipogon and Oryza nivara) are a progenitor-derivative species pair with ecological divergence and provide a unique system for studying ecological adaptation/speciation. Here, we constructed a high-resolution linkage map and conducted a quantitative trait locus (QTL) analysis of 19 phenotypic traits using an F2 population generated from a cross between the two Oryza species. We identified 113 QTLs associated with interspecific divergence of 16 quantitative traits, with effect sizes ranging from 1.61% to 34.1% in terms of the percentage of variation explained (PVE). The distribution of effect sizes of QTLs followed a negative exponential, suggesting that a few genes of large effect and many genes of small effect were responsible for the phenotypic divergence. We observed 18 clusters of QTLs (QTL hotspots) on 11 chromosomes, significantly more than that expected by chance, demonstrating the importance of coinheritance of loci/genes in ecological adaptation/speciation. Analysis of effect direction and v-test statistics revealed that interspecific differentiation of most traits was driven by divergent natural selection, supporting the argument that ecological adaptation/speciation would proceed rapidly under coordinated selection on multiple traits. Our findings provide new insights into the understanding of genetic architecture of ecological adaptation and speciation in plants and help effective manipulation of specific genes or gene cluster in rice breeding.

Therapeutic effect of pH-Responsive dexamethasone prodrug nanoparticles on acute lung injury.

Acute lung injury/inflammation (ALI) is usually caused by various injury factors inside and outside the lung, which can be transformed into acute respiratory distress syndrome (ARDS) in severe cases. Alveolar macrophages play a key role in the pathogenesis of ALI, which regulate inflammatory responses by secreting inflammatory mediators. Therefore, we prepared dexamethasone (DXM)/mannose co-modified branched polyethyleneimine (PEI) (DXM-PEI-mannose, DPM) prodrug nanopartcales, which could effectively target the mannose receptor (MR) on the surface of alveolar macrophages and be used for the treatment of ALI. The DXM-PEI (DP) prodrug was obtained by linking DXM with branched PEI through Schiff base reaction. Subsequently, the pH-responsive DPM prodrug was obtained by using mannose-targeted head modification. The DPM prodrug NPs with a particle size of 115 ± 1 nm, a polydispersity index (PDI) value of 0.054 ± 0.018, and a zeta potential of 31 ± 1 mV were obtained by cross-linking. The drug loading of DPM prodrug NPs measured by the acid hydrolysis method was 51.88%, which had good serum stability and biocompatibility. By comparing the stability and property release of prodrug NPs under different pH (7.4 and 5.0) conditions, it showed that DPM prodrug NPs had certain sensitivity to the micro-acid environment. To study the targeting of mouse mononuclear macrophages, mannose-modified prodrug NPs showed significant in vitro targeting. Moreover, prodrug NPs showed good anti-inflammatory activity in vitro, which was significantly different from free drugs. In vivo biodistribution experiments also showed that it had a long-term lung targeting effect. DPM prodrug NPs also had a good therapeutic effect on ALI. In conclusion, the mannose-modified DXM prodrug NPs delivery system could specifically target lung tissues and have a good therapeutic effect, which might be useful for the treatment of lung diseases.

Retraction Note: Decreased miR-154 expression and its clinical significance in human colorectal cancer.

The Editor-in-Chief is retracting this article [1] due to overlap with the following articles (amongst others) [2-6].

Decreased miR-154 expression and its clinical significance in human colorectal cancer.

BACKGROUND: miRNA-154 (miR-154) has been identified as a tumor suppressor in several types of human cancers. However, its clinical significance in colorectal cancer (CRC) is still unclear. The aim of this study was to analyze the association of miR-154 expression with clinicopathologic features and prognosis in CRC patients. METHODS: Quantitative RT-PCR was performed to evaluate miR-154 levels in 169 pairs of CRC specimens and adjacent noncancerous tissues. Then, the associations of miR-154 expression with clinicopathological factors or survival of patients suffering CRC were determined. RESULTS: The expression levels of miR-154 in CRC tissues were significantly lower than those in corresponding noncancerous tissues (P < 0.001). Decreased miR-154 expression was significantly associated with large tumor size, positive lymph node metastasis, and advanced clinical stage. Moreover, the univariate analysis demonstrated that CRC patients with low miR-154 expression had poorer overall survival (P = 0.006). The multivariate analysis identified low miR-154 expression as an independent predictor of poor survival. CONCLUSIONS: These findings suggested that miR-154 downregulation may be associated with tumor progression of CRC, and that this miR may be an independent prognostic marker for CRC patients.

Extracellular matrix of mechanically stretched cardiac fibroblasts improves viability and metabolic activity of ventricular cells.

BACKGROUND: In heart, the extracellular matrix (ECM), produced by cardiac fibroblasts, is a potent regulator of heart's function and growth, and provides a supportive scaffold for heart cells in vitro and in vivo. Cardiac fibroblasts are subjected to mechanical loading all the time in vivo. Therefore, the influences of mechanical loading on formation and bioactivity of cardiac fibroblasts ECM should be investigated. METHODS: Rat cardiac fibroblasts were cultured on silicone elastic membranes and stimulated with mechanical cyclic stretch. After removing the cells, the ECMs coated on the membranes were prepared, some ECMs were treated with heparinase II (GAG-lyase), then the collagen, glycosaminoglycan (GAG) and ECM proteins were assayed. Isolated neonatal rat ventricular cells were seeded on ECM-coated membranes, the viability and lactate dehydrogenase (LDH) activity of the cells after 1-7 days of culture was assayed. In addition, the ATPase activity and related protein level, glucose consumption ratio and lactic acid production ratio of the ventricular cells were analyzed by spectrophotometric methods and Western blot. RESULTS: The cyclic stretch increased collagen and GAG levels of the ECMs, and elevated protein levels of collagen I and fibronectin. Compared with the ECMs produced by unstretched cardiac fibroblasts, the ECMs of mechanically stretched fibroblasts improved viability and LDH activity, elevated the Na⁺/K⁺-ATPase activity, sarco(endo)plasmic reticulum Ca²âº-ATPase (SERCA) activity and SERCA 2a protein level, glucose consumption ratio and lactic acid production ratio of ventricular cells seeded on them. The treatment with heparinase II reduced GAG levels of these ECMs, and lowered these metabolism-related indices of ventricular cells cultured on the ECMs. CONCLUSIONS: Mechanical stretch promotes ECM formation of cardiac fibroblasts in vitro, the ECM of mechanically stretched cardiac fibroblasts improves metabolic activity of ventricular cells cultured in vitro, and the GAG of the ECMs is involved in regulating metabolic activity of ventricular cells.

Cardiac fibroblast-derived extracellular matrix produced in vitro stimulates growth and metabolism of cultured ventricular cells.

Cardiac fibroblasts (CFs) produce extracellular matrix (ECM) which is a potent regulator of heart cell function and growth, and provides a supportive microenvironment for heart cells. Therefore, CF-derived ECM produced in vitro is very suitable for heart-cell culturing and cardiac tissue engineering. The aim of this study was to investigate the effect of CF-derived ECM produced in vitro on the growth and metabolism of cultured ventricular cells. CF-derived ECM-coated cell culture dishes were prepared by culturing rat CFs and then decellularizing the cultures. Isolated neonatal rat ventricular cells were seeded on ECM-coated, collagen I-coated or uncoated dishes, and the growth of cells after 1-5 days of culture was assayed with MTT reagent. In addition, cellular metabolic activity was analyzed by spectrophotometric methods and protein levels of sarco(endo)plasmic reticulum Ca(2+)-ATPase type 2a (SERCA2a) by Western blotting. The relative growth of ventricular cells was better on ECM-coated than on uncoated or collagen I-coated dishes. Furthermore, the glucose consumption ratio, lactic acid production ratio, Na(+)/K(+)-ATPase activity, SERCA activity and protein levels of SERCA2a were all higher in cells on the ECM-coated dishes. In conclusion, cardiac fi broblast-derived ECM produced in vitro stimulates the growth and metabolism of cultured ventricular cells. This study indicates that the bioactivity of the ECM supports heart cell growth in vitro, and this might be useful for cardiac tissue engineering.

Multiple domestications of Asian rice.

The origin of domesticated Asian rice (Oryza sativa L.) has been controversial for more than half a century. The debates have focused on two leading hypotheses: a single domestication event in China or multiple domestication events in geographically separate areas. These two hypotheses differ in their predicted history of genes/alleles selected during domestication. Here we amassed a dataset of 1,578 resequenced genomes, including an expanded sample of wild rice from throughout its geographic range. We identified 993 selected genes that generated phylogenetic trees on which japonica and indica formed a monophyletic group, suggesting that the domestication alleles of these genes originated only once in either japonica or indica. Importantly, the domestication alleles of most selected genes (~80%) stemmed from wild rice in China, but the domestication alleles of a substantial minority of selected genes (~20%) originated from wild rice in South and Southeast Asia, demonstrating separate domestication events of Asian rice.

Mechanical strain promotes osteoblast ECM formation and improves its osteoinductive potential.

BACKGROUND: The extracellular matrix (ECM) provides a supportive microenvironment for cells, which is suitable as a tissue engineering scaffold. Mechanical stimulus plays a significant role in the fate of osteoblast, suggesting that it regulates ECM formation. Therefore, we investigated the influence of mechanical stimulus on ECM formation and bioactivity. METHODS: Mouse osteoblastic MC3T3-E1 cells were cultured in cell culture dishes and stimulated with mechanical tensile strain. After removing the cells, the ECMs coated on dishes were prepared. The ECM protein and calcium were assayed and MC3T3-E1 cells were re-seeded on the ECM-coated dishes to assess osteoinductive potential of the ECM. RESULTS: The cyclic tensile strain increased collagen, bone morphogenetic protein 2 (BMP-2), BMP-4, and calcium levels in the ECM. Compared with the ECM produced by unstrained osteoblasts, those of mechanically stimulated osteoblasts promoted alkaline phosphatase activity, elevated BMP-2 and osteopontin levels and mRNA levels of runt-related transcriptional factor 2 (Runx2) and osteocalcin (OCN), and increased secreted calcium of the re-seeded MC3T3-E1 cells. CONCLUSION: Mechanical strain promoted ECM production of osteoblasts in vitro, increased BMP-2/4 levels, and improved osteoinductive potential of the ECM. This study provided a novel method to enhance bioactivity of bone ECM in vitro via mechanical strain to osteoblasts.

Cloning of the heat shock protein 60 gene from the stem borer, Chilo suppressalis, and analysis of expression characteristics under heat stress.

Heat shock protein 60 is an important chaperonin. In this paper, hsp60 of the stem borer, Chilo suppressalis (Walker) (Lepidoptera: Pyralidae), was cloned by RT-PCR and rapid amplification of cDNA end (RACE) reactions. The full length cDNA of hsp6 degrees Consisted of 2142 bp, with an ORF of 1719 bp, encoding 572 amino acid residues, with a 5'UTR of 158 bp and a 3'UTR of 265 bp. Cluster analysis confirmed that the deduced amino acid sequence shared high identity with the reported sequences from other insects (77%-86%). To investigate whether hsp60 in C. suppressalis responds to thermal stress, the expression levels of hsp60 mRNA in larval haemocytes across temperature gradients from 31 to 39 degrees C were analysed by real-time quantitative PCR. There was no significant difference for hsp60 expression from 28 to 31 degrees C. he temperatures for maximal induction of hsp60 expression in haemocytes was close to 36 degrees C. Hsp60 expression was observed by using flow cytometry. These results revealed that thermal stress significantly induced hsp60 expression and Hsp60 synthesis in larval haemocytes, and the expression profiles of Hsp60 at the mRNA and protein levels were in high agreement with each other from 33 to 39 degrees C.

Fabrication and release behavior of nitrapyrin Microcapsules: Using modified melamine-formaldehyde resin as shell material.

As a commonly used nitrification inhibitor, nitrapyrin can significantly improve the utilization of nitrogen in soils. However, the effectiveness of the traditional dosage form of nitrapyrin is reduced by soil adsorption. In this study, nitrapyrin was encapsulated into a melamine-formaldehyde resin microcapsule with good dispersion and release behavior using an in situ polymerization method. The nitrapyrin microcapsules were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and particle-size analysis. The results indicated that the microcapsules had a spherical-shell structure, a uniform morphology with nanoscale micropores on the surface, and a decent nitrapyrin loading content (67.19%). Tests revealed that the release behavior of the nitrapyrin microcapsules was outstanding and conformed to the double-release kinetic model. These results of this study indicate that the nitrapyrin microcapsules can be applied as nitrification inhibitors with beneficial environmental effects and high efficacy.

[Effects of temperature stress on physiological indices of Chilo suppressalis Walker (Lepidoptera: Pyralidae) diapause larvae].

To understand the physiological mechanisms of temperature stress on the diapause larvae of rice stem borer Chilo suppressalis Walker at physiological and biochemical levels, determinations were made on the contents of water, lipid, total sugar and low molecular mass carbohydrates and the activities of SOD, POD, CAT in the larvae after series temperature stress (STS) and gradient temperature stress (GTS). With the decrease of temperature, the water content in the larvae decreased, and the decrement below 0 degrees C was significantly larger in treatment GTS than in treatment STS. The lipid content in the larvae decreased gradually, but no significant difference was observed between treatments STS and GTS. The total sugar content in the larvae in treatment STS increased after an initial decrease, but that in treatment GTS continued to decline. Four species of low molecular carbohydrates, i. e. , trehalose, glucose, glycerol and fructose were detected in the larvae. In treatment STS, the contents of glycose, glycerol and fructose in the larvae decreased after an initial increase, while the trehalose content was in adverse. In treatment GTS, the trehalose content decreased first and increased then, the glucose and glycerol were in adverse, but the fructose content had little change. In the range from 14 to -14 degrees C, the SOD and POD activities in the larvae in treatment STS were significantly lower than those in treatment GTS, but the CAT activity was in adverse. The changes of these indices reflected the physiological responses of C. suppressalis diapause larvae to different temperature stress.

Culturing of ventricle cells at high density and construction of engineered cardiac cell sheets without scaffold.

In natural heart tissue, cell density is about 1.0 x 108/cm3, and the cell metabolism is very active. Therefore, culturing heart cells in 3-dimensions at high density and construction of engineered cardiac tissue in vitro is very difficult. The aim of this study was to simulate 3-dimensional culturing of cardiac cells and pursue a novel method to construct engineered cardiac tissue in vitro. The isolated neonatal rat ventricle cells were cultured at a high seeding density of 1 x 10(6)/cm2. The cells at high density metabolized actively; the glucose consumption and lactic acid production of ventricle cells were much greater than those of fibroblasts cultured at the same density. The pH value of the culture medium of ventricle cells consistently decreased more rapidly. These cultured ventricle cells contained vascular endothelial cells, cardiomyocytes, and smooth muscle cells that appeared close to each other, and had overlapping nuclei and plenty of extracellular collagen. The cells at high density were treated with 0.2% trypsin to construct engineered cardiac cell sheets without scaffold. The engineered cardiac cell sheets could beat and roll up spontaneously, each sheet was 3 to 5 cells thick, and contained abundant cardiomyocytes and extracellular collagen. In conclusion, cells cultured at high-density in vitro grew well in a 2-dimensional culturing environment, formed "quasi 3-dimension" culturing, and engineered cardiac cell sheets comprised of several layers of cells were constructed. This study provides some guidance for cardiac tissue engineering and a novel method to construct engineered cardiac tissue without scaffold.

[Dynamic changes of cold-resistant substances of overwintering Chilo suppressalis (Walker) larvae].

Aimed to understand the mechanisms of cold-resistance of overwintering Chilo suppressalis (Walker) larvae at physiological and biochemical levels, the supercooling point (SCP) and the contents of water, ash, elements, fat, fatty acid, glycrol, total sugar, and protein in the larvae samples collected at different time were determined. The results showed that the SCP and the contents of free water, dissociated fat, total sugar, and protein in the overwintering larvae decreased first and increased then, whereas the contents of bound water, ash, combined fat, K, Na, Mg, Fe, Ni and Cr, and glycerol decreased after an initial increase. The components of fatty acids in overwintering larvae had some changes, but the main components were still 9-hexadecenoic acid, 9-hexadecanoic acid, and 9-octadecenoic acid. The contents of 9-hexadecenoic acid and 9-hexadecanoic acid decreased first and increased then, while that of 9-octadecenoic acid was in adverse. The dynamic changes of the contents of test substances could reflect the cold-resistance of overwintering C. suppressalis larvae.