Can arbuscular mycorrhizal fungi improve grain yield, As uptake and tolerance of rice grown under aerobic conditions?

The effects of arbuscular mycorrhizal fungi (AMF) -Glomus intraradices and G. geosporum on arsenic (As) and phosphorus (P) uptake by lowland (Guangyinzhan) and upland rice (Handao 502) were investigated in soil, spiked with and without 60 mg As kg(-1). In As-contaminated soil, Guangyinzhan inoculated with G. intraradices or Handao 502 inoculated with G. geosporum enhanced As tolerance, grain P content, grain yield. However, Guangyinzhan inoculated with G. geosporum or Handao 502 inoculated with G. intraradices decreased grain P content, grain yield and the molar ratio of grain P/As content, and increased the As concentration and the ratio of grain/straw As concentration. These results show that rice/AMF combinations had significant (p < 0.05) effects on grain As concentration, grain yield and grain P uptake. The variation in the transfer and uptake of As and P reflected strong functional diversity in AM (arbuscular mycorrhizal) symbioses.

Comparative analysis with collagen type II distinguishes cartilage oligomeric matrix protein as a primary TGFβ-responsive gene

OBJECTIVE

This study aims to investigate the regulation of expression of Cartilage oligomeric matrix protein (COMP), which is predominately expressed by chondrocytes and functions to organize the extracellular matrix. Mutations in COMP cause two skeletal dysplasias: pseudoachondroplasia and multiple epiphyseal dysplasia. The mechanism controlling COMP expression during chondrocyte differentiation is still poorly understood.

DESIGN

Primary human bone marrow-derived stem cells were induced to differentiate into chondrocyte by pellet cultures. We then compared the temporal expression of COMP with the well-characterized cartilage-specific Type II collagen (Col2a1), and their response to transforming growth factor (TGF)β and Sox trio (Sox5, 6, and 9) stimulation.

RESULTS

COMP and Col2a1 expression are differentially regulated by three distinct mechanisms. First, upregulation of COMP mRNA precedes Col2a1 by several days during chondrogenesis. Second, COMP expression is independent of high cell density but requires TGF-β1. Induction of COMP mRNA by TGF-β1 is detected within 2h in the absence of protein synthesis and is blocked by specific inhibitors of the TGFβ signaling pathway; and therefore, COMP is a primary TFGβ-response gene. Lastly, while Col2a1 expression is intimately controlled by the Sox trio, overexpression of Sox trio fails to activate the COMP promoter.

CONCLUSION

COMP and Col2a1 expression are regulated differently during chondrogenesis. COMP is a primary response gene of TGFβ and its fast induction during chondrogenesis suggests that COMP is suitable for rapidly accessing the chondrogenic potential of stem cells.

Ontogenic changes in placental transthyretin

OBJECTIVES

Before secretion of fetal thyroid hormone at around 16 weeks gestation normal fetal development depends on a constant supply of maternal thyroid hormone (TH), particularly thyroxine (T(4)). The detailed mechanisms of transplacental delivery of TH are still uncertain. The TH binding protein, transthyretin (TTR), is produced and secreted by placenta and may play a role in this process. The ontogeny of placental TTR is unknown. Our aim was to study changes in placental TTR in early and late pregnancy.

STUDY DESIGN

We collected placentas from surgically terminated pregnancies between 6 and 17 weeks gestation (n = 44) and from normal term (38-39 weeks) pregnancies following caesarean section (n = 5). Real time-PCR, western blotting and immunohistochemistry were used to determine TTR mRNA and protein levels.

RESULTS

There were highly significant correlations between gestational age and TTR mRNA (r = 0.974; p < 0.0001) and between gestational age and TTR protein (r = 0.901; p < 0.001) levels between weeks 6 and 13 of gestation. TTR expression did not increase between 13 and 17 weeks and was not different at term. Good correlation was observed between TTR mRNA and TTR protein between individual placental samples (r = 0.916; p < 0.0001). A similar trend was observed using immunohistochemical staining of placental paraffin sections.

CONCLUSIONS

Our results demonstrate that TTR is expressed in the human placenta from at least 6 weeks gestation. Levels rise during the first trimester at a time when placental oxygen tensions are also rising. We hypothesise that TTR production and secretion by the placenta may facilitate transplacental delivery of TH to the fetus.

The effects and mechanisms of blockage of STAT3 signaling pathway on IL-6 inducing EMT in human pancreatic cancer cells in vitro

Aberrant Signal transducers and activators of transcription-3 (STAT3) signaling pathway is a major cause of tumor invasion and metastasis; the underlying mechanisms, however, are not well understood. Epithelial-mesenchymal transition (EMT) is an early event that occurs during invasion of cancers of an epithelial origin. It remains elusive whether STAT3signaling pathway is involved in EMT. The objective of this study was to evaluate the effect of blockage of STAT3 signaling pathway on IL-6 inducing EMT in human pancreatic cancer cells. We used SW1990 cells and induced them to undergo EMT by exposing these cells to soluble factor interleukin-6 (IL-6). The expression of Snail, E-cadherin, and Twist was detected by reverse transcription-PCR, real-time PCR, and Western blotting. Cell morphology was observed under invert phase-contrast microscope.The invasion ability was determined by cell invasion assay in vitro. Our results demonstrated that STAT3 signaling pathway was involved in pancreatic cancer cell invasion and EMT, and that EMT induced by IL-6 was associated with the activation of STAT3 signaling pathway. Inhibition of STAT3 signaling pathway by silencing of the STAT3 gene with RNAi blocked STAT3 signaling pathway activation and suppressed EMT in pancreatic cancer cells. Collectively, the STAT3 signaling pathway plays an important role in the process of EMT of pancreatic cancer by regulating Snail gene expression. Better understanding of STAT3 signaling pathways in EMT may contribute to development of novel therapeutic strategies in invasion and metastasis of pancreatic cancer.

Antifibrotic effects of Smad4 small interfering RNAs in injured skeletal muscle after acute contusion

Muscle injuries are common musculoskeletal problems encountered in sports medicine clinics. In this study, we examined the effect of lentivirus-mediated small interfering RNA (siRNA) targeting Smad4 on the suppression of the fibrosis in injured skeletal muscles. We found that Smad4-siRNA could efficiently knock down the expression of Smad4 in the C2C12 myoblast cells and in the contunded mice gastrocnemius muscle. The expression of mRNA level of Smad4 decreased to 11% and 49% compared to the control group, respectively, and the expression of protein level decreased to 13% and 57% respectively. Moreover, the lentivirus-mediated siRNA was stably transfected only into the skeletal muscle and not into the liver of the animals. In contunded mice gastrocnemius, the collagenous and vimentin-positive area in the Smad4 siRNA group reduced to 36% and 37% compared to the control group, respectively. Furthermore, compared to the scrambled Smad4 siRNA-injected mice and PBS control-injected mice, the muscle function of the mice injected with lentivirus-mediated Smad4 siRNA improved in terms of both fast-twitch and tetanic strength (P<0.05). The results suggest that the gene therapy of inhibiting Smad4 by lentivirus-mediated siRNA could be a useful approach to prevent scar tissue formation and improve the function of injured skeletal muscle.

Notch signaling may negatively regulate neonatal rat cardiac fibroblast-myofibroblast transformation

Cardiac fibroblast-myofibroblast transformation (CMT) is a critical event in the initiation of myocardial fibrosis. Notch signaling has been shown to regulate myofibroblast transformation from other kinds of cells. However, whether Notch signaling is also involved in CMT remains unclear. In the present study, expressions of Notch receptors in cardiac fibroblasts (CFs) were examined, effects of Notch signaling inhibitor N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT) and transforming growth factor-beta1 (TGF-beta1) on CMT were determined by increasing alpha-smooth muscle actin (alpha-SMA) expression and collagen synthesis, and Notch signaling was examined by analyzing expressions of Notch receptors. The results showed that: (1) Notch receptor 1, 2, 3 and 4 were all expressed in CFs; (2) DAPT promoted CMT in a time-dependent manner; (3) During the period of CMT induced by TGF-beta1, expressions of Notch receptor 1, 3 and 4 in CFs were down-regulated, whereas there was no change for Notch receptor 2. Moreover, the downtrends of Notch 1, 3 and 4 were corresponding to the trend growth of alpha-SMA expression and collagen synthesis. These results suggested that inhibiting of Notch signaling might promote CMT. The down-regulations of Notch receptor 1, 3 and 4 induced by TGF-beta1 may facilitate CMT. In conclusion, inhibition of Notch signaling might be a novel mechanism of CMT in myocardial fibrosis.

An adaptive evolutionary multi-objective approach based on simulated annealing

A multi-objective optimization problem can be solved by decomposing it into one or more single objective subproblems in some multi-objective metaheuristic algorithms. Each subproblem corresponds to one weighted aggregation function. For example, MOEA/D is an evolutionary multi-objective optimization (EMO) algorithm that attempts to optimize multiple subproblems simultaneously by evolving a population of solutions. However, the performance of MOEA/D highly depends on the initial setting and diversity of the weight vectors. In this paper, we present an improved version of MOEA/D, called EMOSA, which incorporates an advanced local search technique (simulated annealing) and adapts the search directions (weight vectors) corresponding to various subproblems. In EMOSA, the weight vector of each subproblem is adaptively modified at the lowest temperature in order to diversify the search toward the unexplored parts of the Pareto-optimal front. Our computational results show that EMOSA outperforms six other well established multi-objective metaheuristic algorithms on both the (constrained) multi-objective knapsack problem and the (unconstrained) multi-objective traveling salesman problem. Moreover, the effects of the main algorithmic components and parameter sensitivities on the search performance of EMOSA are experimentally investigated.

Expression of tachykinin receptors inXenopus oocytes injected with poly (A)(+) RNA from cat dorsal root ganglion

The expression of the types of tachykinin receptors in the dorsal root ganglion (DRG) neurons by means ofXenopus oocyte expressing system was studied. Poly(A)(+) RNAs were extracted from cat cervical and lumbar DRG. Two days after injection of Poly (A)(+) RNAs, the oocytes were recorded with the two-electrode voltage clamp technique. In the oocytes injected with DRG poly(A)(+) RNA, [Sar(9), Met(O(2))(11)]-substance P(Sar -SP, 1 mumol/L), neurokinin A (NKA, 1 mumol/L) or [beta-Ala(8)]-neurokinin A((4-10)) (Ala-NKA, 1 mumol/L) produced an inward current comprising a rapid spike and a long sustained oscillatory component for several minutes. Sar-SP induced response was blocked by NK-1 antagonist L-668, 169 (1 mumol/L), but not by NK-2 antagonist L-659, 877(1mumol/L). In contrast, Ala-NKA and NKA responses were only blocked by L-659, 877. The oocytes injected with DH Poly(A)(+)RNA also responded to Sar-SP and NKA with similar inward currents, which were selectively blocked by L-668, 169 and L-659, 877, respectively. These tachykinins-induced responses had a potent desensitization. The present data indicate expression of NK-1 and NK-2 receptors in DRG neurons, suggesting that there may be tachykinin autoreceptors on the nociceptive primary afferent terminals.