An alternative mechanism for shade adaptation: implication of allometric responses of three submersed macrophytes to water depth

Allometric scaling models describing size-dependent biological relationships are important for understanding the adaptive responses of plants to environmental variation. In this study, allometric analysis was used to investigate the biomass allocation and morphology of three submerged macrophytes (Potamogeton maackianus, Potamogeton malaianus and Vallisneria natans) in response to water depth (1.0 and 2.5?m) in an in situ experiment. The three macrophytes exhibited different allometric strategies associated with distinct adjustments in morphology and biomass allocation in response to varying water depths. In deeper water, after accounting for the effects of plant size, P. maackianus and P. malaianus tended to enhance light harvesting by allocating more biomass to the stem, increasing shoot height and specific leaf area. V. natans tended to allocate more biomass to the leaf than to the basal stem (rosette), showing a higher leaf mass ratio and shoot height in deeper water. The three species decreased biomass allocation to roots as water depth increased. The main effect of water depth treatments was reduced light availability, which induced plastic shoot or leaf elongation. This shows that macrophytes have evolved responses to light limitation similar to those of terrestrial plants.     

Chaperone proteostasis in Parkinson's disease: stabilization of the Hsp70/α‐synuclein complex by Hip

The ATP‐dependent protein chaperone heat‐shock protein 70 (Hsp70) displays broad anti‐aggregation functions and has a critical function in preventing protein misfolding pathologies. According to in vitro and in vivo models of Parkinson's disease (PD), loss of Hsp70 activity is associated with neurodegeneration and the formation of amyloid deposits of α‐synuclein (αSyn), which constitute the intraneuronal inclusions in PD patients known as Lewy bodies. Here, we show that Hsp70 depletion can be a direct result of the presence of aggregation‐prone polypeptides. We show a nucleotide‐dependent interaction between Hsp70 and αSyn, which leads to the aggregation of Hsp70, in the presence of ADP along with αSyn. Such a co‐aggregation phenomenon can be prevented in vitro by the co‐chaperone Hip (ST13), and the hypothesis that it might do so also in vivo is supported by studies of a Caenorhabditis elegans model of αSyn aggregation. Our findings indicate that a decreased expression of Hip could facilitate depletion of Hsp70 by amyloidogenic polypeptides, impairing chaperone proteostasis and stimulating neurodegeneration.     

Bradykinin enhances cell migration in human chondrosarcoma cells through BK receptor signaling pathways

Bradykinin (BK) is an inflammatory mediator, and shows elevated levels in regions of severe injury and inflammatory diseases. BK has recently been shown to be involved in carcinogenesis and cancer progression. In this study, we found that BK increased the migration and the expression of α2β1 integrin in human chondrosarcoma cells. We also found that human chondrosarcoma tissues had significantly higher expression of the B1 and B2 receptors comparing to normal cartilage. BK‐mediated migration and integrin up‐regulation was attenuated by B1 and B2 BK receptor siRNA or antagonist. Activations of phospholipase C (PLC), protein kinase Cδ (PKCδ), and NF‐κB pathways after BK treatment was demonstrated, and BK‐induced integrin expression and migration activity was inhibited by the specific inhibitor of PLC, PKCδ, and NF‐κB cascades. Taken together, our results indicated that BK enhances the migration of chondrosarcoma cells by increasing α2β1 integrin expression through the BK receptors/PLC/PKCδ/NF‐κB signal transduction pathway. J. Cell. Biochem. 109: 82–92, 2010. © 2009 Wiley‐Liss, Inc.     

Integrin‐linked kinase is involved in TNF‐α‐induced inducible nitric‐oxide synthase expression in myoblasts

Tumor necrosis factor‐α (TNF‐α) is a pleiotropic cytokine produced by activated macrophages. Nitric oxide (NO) is a highly reactive nitrogen radical implicated in inflammatory responses. We investigated the signaling pathway involved in inducible nitric oxide synthase (iNOS) expression and NO production stimulated by TNF‐α in cultured myoblasts. TNF‐α stimulation caused iNOS expression and NO production in myoblasts (G7 cells). TNF‐α‐mediated iNOS expression was attenuated by integrin‐linked kinase (ILK) inhibitor (KP392) and siRNA. Pretreatment with Akt inhibitor, mammalian target of rapamycin (mTOR) inhibitor (rapamycin), NF‐κB inhibitor (PDTC), and IκB protease inhibitor (TPCK) also inhibited the potentiating action of TNF‐α. Stimulation of cells with TNF‐α increased ILK kinase activity. TNF‐α also increased the Akt and mTOR phosphorylation. TNF‐α mediated an increase of NF‐κB‐specific DNA–protein complex formation, p65 translocation into nucleus, NF‐κB‐luciferase activity was inhibited by KP392, Akt inhibitor, and rapamycin. Our results suggest that TNF‐α increased iNOS expression and NO production in myoblasts via the ILK/Akt/mTOR and NF‐κB signaling pathway. J. Cell. Biochem. 109: 1244–1253, 2010. © 2010 Wiley‐Liss, Inc.     

Thrombin enhanced migration and MMPs expression of human chondrosarcoma cells involves PAR receptor signaling pathway

Thrombin is a multifunctional protease that can activate hemostasis and coagulation through the cleavage of fibrinogen to form fibrin clots. Thrombin also plays a crucial role in migration and metastasis of human cancer cells. However, the effect of thrombin on migration activity in human chondrosarcoma cells is mostly unknown. Here, we found that thrombin increased the migration and expression of matrix metalloproteinase (MMP)‐2 and MMP‐13 in human chondrosarcoma cells (JJ012 and SW1353 cells). By using pharmacological inhibitors or activators or genetic inhibition by the protease‐activated receptor (PAR), we found that the PAR1 and PAR4 receptor but not PAR3 receptor are involved in thrombin‐mediated cell migration and MMPs expression. Thrombin‐mediated migration and MMPs up‐regulation was attenuated by phospholipase C (PLC), protein kinase C, and c‐Src inhibitor. Activations of PLCβ, PKCα, c‐Src, and NF‐κB pathways after thrombin treatment was demonstrated, and thrombin‐induced MMPs expression and migration activity was inhibited by the specific inhibitors and mutants of PLC, PKC, c‐Src, and NF‐κB cascades. Taken together, our results indicated that thrombin enhances the migration of chondrosarcoma cells by increasing MMP‐2 and MMP‐13 expression through the PAR/PLC/PKCα/c‐Src/NF‐κB signal transduction pathway. J. Cell. Physiol. 223:737–745, 2010. © 2010 Wiley‐Liss, Inc.     

A New Prenylated Flavanonol from Seseli annuum Roots Showing Protective Effect on Human Lymphocytes DNA

A new prenylated flavanonol named seselinonol ( 1 ) was isolated from the roots of Seseli annuum, together with the well‐known biologically active polyacetylenes falcarinol ( 2 ) and falcarindiol ( 3 ), and the prenylated furanocoumarin phellopterin ( 4 ). Its structure was elucidated by extensive spectroscopic analysis, including HR‐ESI‐MS, 1D‐ and 2D‐NMR. Seselinonol and phellopterin were tested for in vitro protective effect on chromosome aberrations in peripheral human lymphocytes using cytochalasin‐B blocked micronucleus (CBMN) assay. The new compound exerted a beneficial effect by decreasing DNA damage of human lymphocytes.     

Variable number of tandem repeat markers in the genome sequence of Mycosphaerella fijiensis, the causal agent of black leaf streak disease of banana (Musa spp)

We searched the genome of Mycosphaerella fijiensis for molecular markers that would allow population genetics analysis of this plant pathogen. M. fijiensis, the causal agent of banana leaf streak disease, also known as black Sigatoka, is the most devastating pathogen attacking bananas (Musa spp). Recently, the entire genome sequence of M. fijiensis became available. We screened this database for VNTR markers. Forty-two primer pairs were selected for validation, based on repeat type and length and the number of repeat units. Five VNTR markers showing multiple alleles were validated with a reference set of isolates from different parts of the world and a population from a banana plantation in Costa Rica. Polymorphism information content values varied from 0.6414 to 0.7544 for the reference set and from 0.0400 and 0.7373 for the population set. Eighty percent of the polymorphism information content values were above 0.60, indicating that the markers are highly informative. These markers allowed robust scoring of agarose gels and proved to be useful for variability and population genetics studies. In conclusion, the strategy we developed to identify and validate VNTR markers is an efficient means to incorporate markers that can be used for fungicide resistance management and to develop breeding strategies to control banana black leaf streak disease. This is the first report of VNTR-minisatellites from the M. fijiensis genome sequence.     

Heart rate and burrowing behavior in the mussel Anodontites trapesialis (Bivalvia: Mycetopodidae) from lotic and lentic sites

Burrowing rate index, diurnal variations in heart rate and heart rate alterations associated with behavioral patterns were studied in Anodontites trapesialis from the Pardo River (PR) and the Galo Bravo Dam (GBD). In both populations the pattern immobile/buried was associated with the lowest (basal) values of heart rate, which increase significantly during burrowing remaining steady in its phases I and II and at the first 10 min of phase III. A decrease in the frequency of digging cycles was significantly correlated with the gradual decrease in heart rate during the phase III of burrowing. Nevertheless, mussels from PR burrow faster than those of GBD and possess higher values of basal heart rate which present a diurnal variation with the higher values occurring during the light phase. Yet, the basal heart rate in mussels from GBD remained stable over the course of 24 h. Also, the increase in heart rate associated with burrowing was higher in mussels from PR and compatible with the highest burrowing index previously detected. Since mussels possess a plastic phenotype it is probable that the cited functional differences are phenotypic adaptations, but we cannot exclude the possibility of these adaptations being genotypic in nature.