Fruit dimorphism inPhaseolus sublobatus (Fabaceae) and its evolutionary significance

Populations of the annualPhaseolus sublobatus from different ecogeographical zones are genetically differentiated. In twelve populations from the western ghats (Maharashtra range) chasmogamous flowers are arranged in peduncled capitate racemes borne in leaf axils of higher nodes. One population (Poona Race S₄) has additional inflorescences, also with chasmogamous flowers, on the main axis between the cotyledonary node and the ground. When the pods of these flowers ripen, the inflorescence gradually coils and, eventually, gets bury the fruits in the soil. This phenomenon is not known in any other plant.—The seed-coat patterns as revealed by SEM, and germination behaviour of both aerial and subterranean seeds are similar, and both types of seeds lack dormancy.—Heavy seed predation selection pressure is probably the principal cause for the evolution of fruit dimorphism inP. sublobatus. The origin of geocarpy in relation to fruit dimorphism and seed predation is discussed.     

Alcohol Consumption Negates Estrogen-mediated Myocardial Repair in Ovariectomized Mice by Inhibiting Endothelial Progenitor Cell Mobilization and Function

We have shown previously that estrogen (estradiol, E2) supplementation enhances voluntary alcohol consumption in ovariectomized female rodents and that increased alcohol consumption impairs ischemic hind limb vascular repair. However, the effect of E2-induced alcohol consumption on post-infarct myocardial repair and on the phenotypic/functional properties of endothelial progenitor cells (EPCs) is not known. Additionally, the molecular signaling of alcohol-estrogen interactions remains to be elucidated. This study examined the effect of E2-induced increases in ethanol consumption on post-infarct myocardial function/repair. Ovariectomized female mice, implanted with 17β-E2 or placebo pellets were given access to alcohol for 6 weeks and subjected to acute myocardial infarction. Left ventricular functions were consistently depressed in mice consuming ethanol compared with those receiving only E2. Alcohol-consuming mice also displayed significantly increased infarct size and reduced capillary density. Ethanol consumption also reduced E2-induced mobilization and homing of EPCs to injured myocardium compared with the E2-alone group. In vitro, exposure of EPCs to ethanol suppressed E2-induced proliferation, survival, and migration and markedly altered E2-induced estrogen receptor-dependent cell survival signaling and gene expression. Furthermore, ethanol-mediated suppression of EPC biology was endothelial nitric oxide synthase-dependent because endothelial nitric oxide synthase-null mice displayed an exaggerated response to post-acute myocardial infarction left ventricular functions. These data suggest that E2 modulation of alcohol consumption, and the ensuing EPC dysfunction, may negatively compete with the beneficial effects of estrogen on post-infarct myocardial repair.     

Enhancement of thermal stability and inhibition of protein aggregation by osmolytic effect of hydroxyproline

A combination of spectroscopic, calorimetric, and microscopic studies to understand the effect of hydroxyproline on the thermal stability, conformation, biological activity, and aggregation of proteins has been investigated. Significantly increased protein stability and suppression of aggregation is achieved in the presence of hydroxyproline. For example, exceptional increase in the thermal stability of lysozyme up to 26.4 degrees C and myoglobin up to 31.8 degrees C is obtained in the presence of hydroxyproline. The increased thermal stability of the proteins is observed to be accompanied with significant rise of the catalytic activity. Hydroxyproline is observed to prevent lysozyme fibril formation in vitro. Fluorescence and circular dichroism studies indicate induction of tertiary structures of the studied proteins in the presence of hydroxyproline. Preferential hydration of the native state is found to be crucial for the mechanism of protein stabilization by hydroxyproline. We compared the effect of hydroxyproline to that of proline and observed similar increase in the activity and suppression of protein aggregation. The results demonstrate the use of hydroxyproline as a protein stabilizer and in the prevention of protein aggregation and fibril formation.     

Novel MicroRNA-455-3p and its protective effects against abnormal APP processing and amyloid beta toxicity in Alzheimer's disease

The purpose of our study is to understand the protective role of miR-455-3p against abnormal amyloid precursor protein (APP) processing, amyloid beta (Aβ) formation, defective mitochondrial biogenesis/dynamics and synaptic damage in AD progression. In-silico analysis of miR-455-3p has identified the APP gene as a putative target. Using mutant APP cells, miR-455-3p construct, biochemical and molecular assays, immunofluorescence and transmission electron microscopy (TEM) analyses, we studied the protective effects of miR-455-3p on – 1) APP regulation, amyloid beta (Aβ)(1–40) & (1–42) levels, mitochondrial biogenesis & dynamics; 3) synaptic activities and 4) cell viability & apoptosis. Our luciferase reporter assay confirmed the binding of miR-455-3p at the 3’UTR of APP gene. Immunoblot, sandwich ELISA and immunostaining analyses revealed that the reduced levels of the mutant APP, Aβ(1–40) & Aβ(1–42), and C99 by miR-455-3p. We also found the reduced levels of mRNA and proteins of mitochondrial biogenesis (PGC1α, NRF1, NRF2, and TFAM) and synaptic genes (synaptophysin and PSD95) in mutant APP cells; on the other hand, mutant APP cells that express miR-455-3p showed increased mRNA and protein levels of biogenesis and synaptic genes. Additionally, expression of mitochondrial fission proteins (DRP1 and FIS1) were decreased while the fusion proteins (OPA1, Mfn1 and Mfn2) were increased by miR-455-3p. Our TEM analysis showed a decrease in mitochondria number and an increase in the size of mitochondrial length in mutant APP cells transfected with miR-455-3p. Based on these observations, we cautiously conclude that miR-455-3p regulate APP processing and protective against mutant APP-induced mitochondrial and synaptic abnormalities in AD.     

An efficient in vitro shoot regeneration from leaf petiolar explants and ex vitro rooting of Bixa orellana L.- A dye yielding plant

Physiology and Molecular Biology of Plants - Bixa orellana L. (Bixaceae) is a multipurpose tree grown for the production of commercially important dyes. In the present study, an efficient,...     

Lipid Phosphate Phosphatase 3 Stabilization of β-Catenin Induces Endothelial Cell Migration and Formation of Branching Point Structures

Endothelial cell (EC) migration, cell-cell adhesion, and the formation of branching point structures are considered hallmarks of angiogenesis; however, the underlying mechanisms of these processes are not well understood. Lipid phosphate phosphatase 3 (LPP3) is a recently described p120-catenin-associated integrin ligand localized in adherens junctions (AJs) of ECs. Here, we tested the hypothesis that LPP3 stimulates β-catenin/lymphoid enhancer binding factor 1 (β-catenin/LEF-1) to induce EC migration and formation of branching point structures. In subconfluent ECs, LPP3 induced expression of fibronectin via β-catenin/LEF-1 signaling in a phosphatase and tensin homologue (PTEN)-dependent manner. In confluent ECs, depletion of p120-catenin restored LPP3-mediated β-catenin/LEF-1 signaling. Depletion of LPP3 resulted in destabilization of β-catenin, which in turn reduced fibronectin synthesis and deposition, which resulted in inhibition of EC migration. Accordingly, reexpression of β-catenin but not p120-catenin in LPP3-depleted ECs restored de novo synthesis of fibronectin, which mediated EC migration and formation of branching point structures. In confluent ECs, however, a fraction of p120-catenin associated and colocalized with LPP3 at the plasma membrane, via the C-terminal cytoplasmic domain, thereby limiting the ability of LPP3 to stimulate β-catenin/LEF-1 signaling. Thus, our study identified a key role for LPP3 in orchestrating PTEN-mediated β-catenin/LEF-1 signaling in EC migration, cell-cell adhesion, and formation of branching point structures.Angiogenesis, the formation of new blood vessels, involves several well-coordinated cellular processes, including endothelial cell (EC) migration, synthesis and deposition of extracellular matrix proteins, such as fibronectin, cell-cell adhesion, and formation of branching point structures (1-3, 19, 33); however, less is known about the underlying mechanisms of these processes (6, 8, 12, 14, 16, 17). For example, adherens junctions (AJs), which mediate cell-cell adhesion between ECs, may be involved in limiting the extent of cell migration (2, 14, 38, 40). VE-cadherin, a protein found in AJs, is a single-pass transmembrane polypeptide responsible for calcium-dependent homophilic interactions through its extracellular domains (2, 38, 40). The VE-cadherin cytoplasmic domain interacts with the Armadillo domain-containing proteins, β-catenin, γ-catenin (plakoglobin), and p120-catenin (p120ctn) (2, 15, 38, 40, 43). Genetic and biochemical evidence documents a crucial role of β-catenin in regulating cell adhesion as well as proliferation secondary to the central position of β-catenin in the Wnt signaling pathway (13, 16, 25, 31, 44). In addition, the juxtamembrane protein p120ctn regulates AJ stability via binding to VE-cadherin (2, 7, 9, 15, 21, 28, 32, 43). The absence of regulation or inappropriate regulation of β-catenin and VE-cadherin functions is linked to cardiovascular disease and tumor progression (2, 6).We previously identified lipid phosphate phosphatase 3 (LPP3), also known as phosphatidic acid phosphatase 2b (PAP2b), in a functional assay of angiogenesis (18, 19, 41, 42). LPP3 not only exhibits lipid phosphatase activity but also functions as a cell-associated integrin ligand (18, 19, 35, 41, 42). The known LPPs (LPP1, LPP2, and LPP3) (20-23) are six transmembrane domain-containing plasma membrane-bound enzymes that dephosphorylate sphingosine-1-phosphate (S1P) and its structural homologues, and thus, these phosphatases generate lipid mediators (4, 5, 23, 35, 39). All LPPs, which contain a single N-glycosylation site and a putative lipid phosphatase motif, are situated such that their N and C termini are within the cell (4, 5, 22, 23, 35, 39). Only the LPP3 isoform contains an Arg-Gly-Asp (RGD) sequence in the second extracellular loop, and this RGD sequence enables LPP3 to bind integrins (18, 19, 22). Transfection experiments with green fluorescent protein (GFP)-tagged LPP1 and LPP3 showed that LPP1 is apically sorted, whereas LPP3 colocalized with E-cadherin at cell-cell contact sites with other Madin-Darby canine kidney (MDCK) cells (22). Mutagenesis and domain swapping experiments established that LPP1 contains an apical targeting signal sequence (FDKTRL) in its N-terminal segment. In contrast, LPP3 contains a dityrosine (109Y/110Y) basolateral sorting motif (22). Interestingly, conventional deletion of Lpp3 is embryonic lethal, since the Lpp3 gene plays a critical role in extraembryonic vasculogenesis independent of its lipid phosphatase activity (11). In addition, an LPP3-neutralizing antibody was shown to prevent cell-cell interactions (19, 42) and angiogenesis (42). Here, we addressed the hypothesis that LPP3 plays a key role in EC migration, cell-cell adhesion, and formation of branching point structures by stimulating β-catenin/lymphoid enhancer binding factor 1 (β-catenin/LEF-1) signaling.     

Suppressor cell activity of intestinal mucosal leucocytes from buffalo (Bubalus bubalis arni)

Suppressor activity of buffalo intestinal intraepithelial leucocytes and lamina propria leucocytes was induced by Concanavalin A, and was assayed against the mitogenic response of autologous and allogenic leucocytes to mitogens. Appreciable suppression was observed with 25 micrograms ConA/ml on the proliferative activity of the responder cells cocultured at a ratio of < 2:1 (suppressor:responder cell). Mitomycin C treatment of intestinal leucocytes did not totally vanish the viability and functionality of leucocytes.     

Dissecting the functional role of polyketide synthases in Dictyostelium discoideum: biosynthesis of the differentiation regulating factor 4-methyl-5-pentylbenzene-1,3-diol

Dictyostelium discoideum exhibits the largest repository of polyketide synthase (PKS) proteins of all known genomes. However, the functional relevance of these proteins in the biology of this organism remains largely obscure. On the basis of computational, biochemical, and gene expression studies, we propose that the multifunctional Dictyostelium PKS (DiPKS) protein DiPKS1 could be involved in the biosynthesis of the differentiation regulating factor 4-methyl-5-pentylbenzene-1,3-diol (MPBD). Our cell-free reconstitution studies of a novel acyl carrier protein Type III PKS didomain from DiPKS1 revealed a crucial role of protein-protein interactions in determining the final biosynthetic product. Whereas the Type III PKS domain by itself primarily produces acyl pyrones, the presence of the interacting acyl carrier protein domain modulates the catalytic activity to produce the alkyl resorcinol scaffold of MPBD. Furthermore, we have characterized an O-methyltransferase (OMT12) from Dictyostelium with the capability to modify this resorcinol ring to synthesize a variant of MPBD. We propose that such a modification in vivo could in fact provide subtle variations in biological function and specificity. In addition, we have performed systematic computational analysis of 45 multidomain PKSs, which revealed several unique features in DiPKS proteins. Our studies provide a new perspective in understanding mechanisms by which metabolic diversity could be generated by combining existing functional scaffolds.