Maintenance of higher H(2)O(2) levels, and its mechanism of action to induce growth in breast cancer cells: Important roles of bioactive catalase and PP2A

We assessed the catalase bioactivity and hydrogen peroxide (H(2)O(2)) production rate in human breast cancer (HBC) cell lines and compared these with normal human breast epithelial (HBE) cells. We observed that the bioactivity of catalase was decreased in HBC cells when compared with HBE cells. This was also accompanied by an increase in H(2)O(2) steady-state levels in HBC cells. Silencing the catalase gene led to a further increase in the steady-state level of H(2)O(2) which was also accompanied by an increase in growth rate of HBC cells. Catalase activity was up regulated on treatment with superoxide (O(2)(-)) scavengers such as pegylated SOD (PEG-SOD, indicating inhibition of catalase by the increased O(2)(-) produced by HBC cells. Transfection of either catalase or glutathione peroxidase to HBC cells decreased intracellular H(2)O(2) levels and led to apoptosis of these cells. The H(2)O(2) produced by HBC cells inhibited PP2A activity accompanied by increased phosphorylation of Akt and ERK1/2. The importance of catalase bioactivity in breast cancer was further confirmed as its bioactivity was also decreased in human breast cancer tissues when compared to normal breast tissues. We conclude that inhibition of catalase bioactivity by O(2)(-) leads to an increase in steady-state levels of H(2)O(2) in HBC cells, which in turn inhibits PP2A activity, leading to phosphorylation of ERK 1/2 and Akt and resulting in HBC cell proliferation.     

Escape Behavior of the Formosan Subterranean Termite (Isoptera: Rhinotermitidae) in Response to Disturbance

Disturbances to monitors and baits have often been noted as a confounding factor for the success of termite baiting systems. We studied escape behavior of Coptotermes formosanus Shiraki to a food source disturbance in the laboratory. Four peripheral chambers connected to the central food chamber through tubes served as escape routes from which escape patterns, escape and return times and differences in soldier and worker responses were recorded. We used two sand conditions: moist and dry to test whether favorable versus unfavorable conditions change escape behavior. The post disturbance responses were video recorded for 1 h. C. formosanus quickly escaped from the central chamber when disturbed. The time taken to reach the maximum number of termites that escaped ranged from 20 s to 210 s followed by a gradual return to the disturbed chamber. The majority of the escapees returned to the disturbed area within a few minutes after evacuation in both dry and wet sand conditions. A significantly higher percentage of termites escaped in wet sand arenas (43%) than in the dry sand arenas (31%). Our experiments demonstrate that C. formosanus is highly unlikely to abandon bait stations for extensive periods of time as a result of mechanical disturbances regardless of habitat quality.     

Isorhamnetin Inhibits Proliferation and Invasion and Induces Apoptosis through the Modulation of Peroxisome Proliferator-activated Receptor γ Activation Pathway in Gastric Cancer

Gastric cancer (GC) is a lethal malignancy and the second most common cause of cancer-related deaths. Although treatment options such as chemotherapy, radiotherapy, and surgery have led to a decline in the mortality rate due to GC, chemoresistance remains as one of the major causes for poor prognosis and high recurrence rate. In this study, we investigated the potential effects of isorhamnetin (IH), a 3′-O-methylated metabolite of quercetin on the peroxisome proliferator-activated receptor γ (PPAR-γ) signaling cascade using proteomics technology platform, GC cell lines, and xenograft mice model. We observed that IH exerted a strong antiproliferative effect and increased cytotoxicity in combination with chemotherapeutic drugs. IH also inhibited the migratory/invasive properties of GC cells, which could be reversed in the presence of PPAR-γ inhibitor. We found that IH increased PPAR-γ activity and modulated the expression of PPAR-γ regulated genes in GC cells. Also, the increase in PPAR-γ activity was reversed in the presence of PPAR-γ-specific inhibitor and a mutated PPAR-γ dominant negative plasmid, supporting our hypothesis that IH can act as a ligand of PPAR-γ. Using molecular docking analysis, we demonstrate that IH formed interactions with seven polar residues and six nonpolar residues within the ligand-binding pocket of PPAR-γ that are reported to be critical for its activity and could competitively bind to PPAR-γ. IH significantly increased the expression of PPAR-γ in tumor tissues obtained from xenograft model of GC. Overall, our findings clearly indicate that antitumor effects of IH may be mediated through modulation of the PPAR-γ activation pathway in GC.     

Cytoplasmic and genomic effects on meiotic pairing in brassica hybrids and allotetraploids from pair crosses of three cultivated diploids

Interspecific hybridization and allopolyploidization contribute to the origin of many important crops. Synthetic Brassica is a widely used model for the study of genetic recombination and "fixed heterosis" in allopolyploids. To investigate the effects of the cytoplasm and genome combinations on meiotic recombination, we produced digenomic diploid and triploid hybrids and trigenomic triploid hybrids from the reciprocal crosses of three Brassica diploids (B. rapa, AA; B. nigra, BB; B. oleracea, CC). The chromosomes in the resultant hybrids were doubled to obtain three allotetraploids (B. juncea, AA.BB; B. napus, AA.CC; B. carinata, BB.CC). Intra- and intergenomic chromosome pairings in these hybrids were quantified using genomic in situ hybridization and BAC-FISH. The level of intra- and intergenomic pairings varied significantly, depending on the genome combinations and the cytoplasmic background and/or their interaction. The extent of intragenomic pairing was less than that of intergenomic pairing within each genome. The extent of pairing variations within the B genome was less than that within the A and C genomes, each of which had a similar extent of pairing. Synthetic allotetraploids exhibited nondiploidized meiotic behavior, and their chromosomal instabilities were correlated with the relationship of the genomes and cytoplasmic background. Our results highlight the specific roles of the cytoplasm and genome to the chromosomal behaviors of hybrids and allopolyploids.     

Recruitment of memory B cells to lymph nodes remote from the site of immunization requires an inflammatory stimulus

Successful recall Ab responses require recruitment of quiescent memory B cells to secondary lymphoid organs. However, the cellular dynamics of memory cells responding to local antigenic challenge at lymphoid sites distal from the initial Ag encounter are not well understood. We show in this study that memory B cells generated following s.c. immunization in one footpad generate secondary responses to soluble Ag given i.p. but not to Ag given s.c. in the contralateral footpad unless LPS is coadministered. Memory B cells do not express CD62L, and CD62L(-ve) cells cannot enter lymph nodes unless LPS-mediated inflammation is induced there. Functional TLR4 is required on the B cells, as well as on non-B cells, in the lymph node to achieve full recruitment. Furthermore, splenectomized mice fail to respond to such inflammatory s.c. challenge in contralateral footpads, unlike lymphadenectomized mice lacking the original draining lymph nodes. Splenectomized mice also fail to respond to i.p. challenge with soluble Ag. Together, these data indicate that, unlike the central memory pool of T cells, which circulates through resting lymph nodes, the majority of long-lived memory B cells are spleen resident and require inflammatory signals for mounting recall responses at distal challenge sites.     

Polyacrylamide grafted Agar: Synthesis and applications of conventional and microwave assisted technique

Polyacrylamide grafted Agar (Ag-g-PAM) has been successfully synthesized by conventional method and microwave assisted method. The former method employs ceric ammonium nitrate (CAN) as the free radical initiator while the latter uses the combination of ceric ammonium nitrate (CAN) and microwave irradiation. The synthesized graft copolymers have been characterized by elemental analysis (C, H, N, O and S), FTIR spectroscopy, intrinsic viscosity measurement and scanning electron micrograph (SEM); taking agar as a reference. Flocculation efficacy of synthesized graft copolymers was studied in kaolin suspension and in waste water through 'Jar test' procedure. In the present investigation, we have observed that polyacrylamide grafted agar synthesized by microwave assisted technique shows superior properties than conventional technique. These properties are reported in terms of intrinsic viscosity, flocculation efficacy and pollutant load reduction of waste water.     

Quantitative estimation of insect diversity inhabiting Calotropis procera in industrial and nonindustrial areas of West Bengal, India

This paper compares the species richnesses, Bray–Curtis similarities, species diversities, evennesses, and the results of various analyses (multivariate, logarithmic series, and lognormal distribution analyses) of insects from four orders (viz., Hemiptera, Orthoptera, aculeate Hymenoptera, and Coleoptera) inhabiting a medicinal plant, Calotropis procera among eight sites within industrial and nonindustrial zones in the Purba Medinipur district (erstwhile Midnapore), West Bengal, India. Both cluster analysis and principal component analysis indicate an effect of industrialization on the diversity of the four insect orders. The species community at each site exhibits an almost pure lognormal distribution. Bootstrap estimation of species diversity also points to the effect of industrialization. A comparison of the values of x and N/S of the logarithmic series indicates a typical relationship between the species community and its diversity. The number of unique species among the eight study sites is 6 according to jackknife estimation. Beta-diversity analysis of the samples shows the impact of industrialization on the abundances and species richness of the insects. Altogether, 16 types of analytical procedure are applied for this purpose, and their suitabilities for this kind of data set are assessed. Disturbance, probably due to industrial emissions, has changed the compositions and structures of the insect communities out to a distance of at least 6 km from the core industrial area.     

SOS induction and mutagenesis by dnaQ missense alleles in wild type cells

Mistranslation leads to elevated mutagenesis and replication arrest, both of which are hypothesized to result from the presence of mixed populations of wild type and mistranslated versions of DNA polymerase III subunit proteins. Consistent with this possibility, expression of missense alleles of dnaQ (which codes for the proofreading subunit ?) in wild type (dnaQ+) cells is shown to lead to SOS induction as well as mutagenesis. Exposure to sublethal concentrations of streptomycin, an aminoglycoside antibiotic known to promote mistranslation, also leads to SOS induction.     

An RGS4-mediated phenotypic switch of bronchial smooth muscle cells promotes fixed airway obstruction in asthma

In severe asthma, bronchodilator- and steroid-insensitive airflow obstruction develops through unknown mechanisms characterized by increased lung airway smooth muscle (ASM) mass and stiffness. We explored the role of a Regulator of G-protein Signaling protein (RGS4) in the ASM hyperplasia and reduced contractile capacity characteristic of advanced asthma. Using immunocytochemical staining, ASM expression of RGS4 was determined in endobronchial biopsies from healthy subjects and those from subjects with mild, moderate and severe asthma. Cell proliferation assays, agonist-induced calcium mobilization and bronchoconstriction were determined in cultured human ASM cells and in human precision cut lung slices. Using gain- and loss-of-function approaches, the precise role of RGS proteins was determined in stimulating human ASM proliferation and inhibiting bronchoconstriction. RGS4 expression was restricted to a subpopulation of ASM and was specifically upregulated by mitogens, which induced a hyperproliferative and hypocontractile ASM phenotype similar to that observed in recalcitrant asthma. RGS4 expression was markedly increased in bronchial smooth muscle of patients with severe asthma, and expression correlated significantly with reduced pulmonary function. Whereas RGS4 inhibited G protein-coupled receptor (GPCR)-mediated bronchoconstriction, unexpectedly RGS4 was required for PDGF-induced proliferation and sustained activation of PI3K, a mitogenic signaling molecule that regulates ASM proliferation. These studies indicate that increased RGS4 expression promotes a phenotypic switch of ASM, evoking irreversible airway obstruction in subjects with severe asthma.