Crystal structure of tRNA m1A58 methyltransferase TrmI from Aquifex aeolicus in complex with S-adenosyl-l-methionine

The N ¹-methyladenosine residue at position 58 of tRNA is found in the three domains of life, and contributes to the stability of the three-dimensional L-shaped tRNA structure. In thermophilic bacteria, this modification is important for thermal adaptation, and is catalyzed by the tRNA m¹A58 methyltransferase TrmI, using S-adenosyl-l-methionine (AdoMet) as the methyl donor. We present the 2.2 Å crystal structure of TrmI from the extremely thermophilic bacterium Aquifex aeolicus, in complex with AdoMet. There are four molecules per asymmetric unit, and they form a tetramer. Based on a comparison of the AdoMet binding mode of A. aeolicus TrmI to those of the Thermus thermophilus and Pyrococcus abyssi TrmIs, we discuss their similarities and differences. Although the binding modes to the N6 amino group of the adenine moiety of AdoMet are similar, using the side chains of acidic residues as well as hydrogen bonds, the positions of the amino acid residues involved in binding are diverse among the TrmIs from A. aeolicus, T. thermophilus, and P. abyssi.     

The Neuroprotective Effects of α-Iso-cubebene on Dopaminergic Cell Death: Involvement of CREB/Nrf2 Signaling

As a part of ongoing studies to elucidate pharmacologically active components of Schisandra chinensis, we isolated and studied α-iso-cubebene. The neuroprotective mechanisms of α-iso-cubebene in human neuroblastoma SH-SY5Y cells were investigated. α-Iso-cubebene significantly inhibited cytotoxicity and apoptosis due to 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in dopaminergic SH-SY5Y cells. Pretreatment of cells with α-iso-cubebene reduced intracellular accumulation of ROS and calcium in response to 6-OHDA. The neuroprotective effects of α-iso-cubebene were found to result from protecting the mitochondrial membrane potential. Notably, α-iso-cubebene inhibited the release of apoptosis-inducing factor from the mitochondria into the cytosol and nucleus after 6-OHDA treatment. α-Iso-cubebene also induced the activation of PKA/PKB/CREB/Nrf2 and suppressed 6-OHDA-induced neurotoxicity. α-Iso-cubebene was found to induce phosphorylation of PKA and PKB and activate Nrf2 and CREB signaling pathways in a dose-dependent manner. Additionally, α-iso-cubebene stimulated the expression of the antioxidant response genes NQO1 and HO-1. Finally, α-iso-cubebene-mediated neuroprotective effects were found to be reversible after transfection with CREB and Nrf2 small interfering RNAs.     

Detection of polyketide synthase and nonribosomal peptide synthetase biosynthetic genes from antimicrobial coral-associated actinomycetes

The diversity and properties of actinobacteria, predominant residents in coral holobionts, have been rarely documented. In this study, we aimed to explore the species diversity, antimicrobial activities and biosynthetic potential of culturable actinomycetes within the tissues of the scleractinian corals Porites lutea, Galaxea fascicularis and Acropora millepora from the South China Sea. A total of 70 strains representing 13 families and 15 genera of actinobacteria were isolated. The antimicrobial activity and biosynthetic potential of fifteen representative filamentous actinomycetes were estimated. Crude fermentation extracts of 6 strains exhibited comparable or greater activities against Vibrio alginolyticus than ciprofloxacin. Seven of the 15 actinomycetes strains possess type I polyketide synthases (PKS-I) and/or nonribosomal peptide synthetases (NRPS) genes. Nine tested strains possess type II polyketide synthases (PKS-II). Phylogenetic analysis based on 16S rRNA gene sequences indicated that these PKS and NRPS gene screening positive strains belong to genera Nocardiopsis, Pseudonocardia, Streptomyces, Micromonospora, Amycolatopsis and Prauserella. One PKS-I and four NRPS fragments showed <70 % similarity to their closest relatives, which suggested the novelty of these genes. This study helps uncover the genetic capacity of stony coral-associated actinomycetes to produce bioactive molecules.     

Relationship of Cob characters with Grain Morphology in Maize (Zea mays,Poaceae)

Twenty varieties of maize (Zea mays, Poaceae) were studied through 11 attributes in three to seven randomly selected plants of each variety with a view to understanding the effect of cob characters on technologically desirable grain qualities. Canonical discriminant analysis showed thatproductivity (determined by total grain weight/cob, cob diameter and average grain weight) was the most discriminating among varieties followed by round grains fraction (represented by whole top and middle flat grains, number of rows and grain count/surface area), middle flat grains (composed of middle flat grains and grain count/surface area) and shape of the cob (determined by shape index, total grain weight/cob and cob diameter), which accounted for 35.1, 18.3, 12.2, and 9.8% of the total variance, respectively. In the light of these results, tentative norms have been suggested to evolve maize varieties of superior technological properties and yet retain high productivity. A cylindrical cob of large diameter with highest number of grains/area and smallest possible number of rows together constituted an ideal combination to achieve the objectives. Such possibilities in the light of available information are discussed.     

Protective Effect of Naringenin in Experimental Ischemic Stroke: Down-Regulated NOD2, RIP2, NF-κB,MMP-9 and Up-Regulated Claudin-5 Expression

Inflammatory damage plays a pivotal, mainly detrimental role in cerebral ischemic pathogenesis and may represent a promising target for treatment. Naringenin (NG) has gained growing appreciation for its beneficial biological effects through its anti-inflammatory property. Whether this protective effect applies to cerebral ischemic injury, we therefore investigate the potential neuroprotective role of NG and the underlying mechanisms. Focal cerebral ischemia in male Sprague–Dawley rats was induced by permanent middle cerebral artery occlusion (pMCAO) and NG was pre-administered intragastrically once daily for four consecutive days before surgery. Neurological deficit, brain water content and infarct volume were measured at 24 h after stroke. Immunohistochemistry, Western blot and RT-qPCR were used to explore the anti-inflammatory potential of NG in the regulation of NOD2, RIP2 and NF-κB in ischemic cerebral cortex. Additionally, the activities of MMP-9 and claudin-5 were analyzed to detect NG’s influence on blood–brain barrier. Compared with pMCAO and Vehicle groups, NG noticeably improved neurological deficit, decreased infarct volume and edema at 24 h after ischemic insult. Consistent with these results, our data also indicated that NG significantly downregulated the expression of NOD2, RIP2, NF-κB and MMP-9, and upregulated the expression of claudin-5 (P < 0.05). The results provided a neuroprotective profile of NG in cerebral ischemia, this effect was likely exerted by down-regulated NOD2, RIP2, NF-κB, MMP-9 and up-regulated claudin-5 expression.     

Influence of bovine lactoferrin on the growth of selected probiotic bacteria under aerobic conditions

Bovine lactoferrin (bLf) is a natural glycoprotein, and it shows broad-spectrum antimicrobial activity. However, reports on the influences of bLf on probiotic bacteria have been mixed. We examined the effects of apo-bLf (between 0.25 and 128 mg/mL) on both aerobic and anaerobic cultures of probiotics. We found that bLf had similar effects on the growth of probiotics under aerobic or anaerobic conditions, and that it actively and significantly (at concentrations of >0.25 mg/mL) retarded the growth rate of Bifidobacterium bifidum (ATCC 29521), B. longum (ATCC 15707), B. lactis (BCRC 17394), B. infantis (ATCC 15697), Lactobacillus reuteri (ATCC 23272), L. rhamnosus (ATCC 53103), and L. coryniformis (ATCC 25602) in a dose-dependent manner. Otherwise, minimal inhibitory concentrations (MICs) were 128 or >128 mg/mL against B. bifidum, B. longum, B. lactis, L. reuteri, and L. rhamnosus (ATCC 53103). With regard to MICs, bLf showed at least four-fold lower inhibitory effect on probiotics than on pathogens. Intriguingly, bLf (>0.25 mg/mL) significantly enhanced the growth of Rhamnosus (ATCC 7469) and L. acidophilus (BCRC 14065) by approximately 40–200 %, during their late periods of growth. Supernatants produced from aerobic but not anaerobic cultures of L. acidophilus reduced the growth of Escherichia coli by about 20 %. Thus, bLf displayed a dose-dependent inhibitory effect on the growth of most probiotic strains under either aerobic or anaerobic conditions. An antibacterial supernatant prepared from the aerobic cultures may have significant practical use.     

NDRG1 expression is related to the progression and prognosis of gastric cancer patients through modulating proliferation,invasion and cell cycle of gastric cancer cells

N-myc downstream-regulated gene 1 (NDRG1) has been proposed as a tumor suppressor gene in many different types of tumors, but its potential function and corresponding mechanism are not yet fully elucidated. This study aims to detect the possible function of NDRG1 in gastric cancer progression. In this study, 112 paired gastric cancer tissues and corresponding nonmalignant gastric tissues were utilized to identify the differential protein expression of NDRG1 by immunohistochemistry and its clinical significance was analyzed. Furthermore, 49 of 112 paired gastric specimens were used to detect the differential mRNA expression by real-time PCR. The over expression of NDRG1 in human gastric cancer cell line AGS by PcDNA3.1–NDRG1 transfection was utilized to detect the role of NDRG1 in regulating the biological behavior of gastric cancer. NDRG1 expression was significantly decreased in primary gastric cancer tissues, compared with its corresponding nonmalignant gastric tissues (p < 0.05), and its decreased expression was significantly associated with lymph node metastasis (p < 0.01), invasion depth (p < 0.01) and differentiation (p < 0.05). Additionally, the overall survival rate of gastric cancer patients with high expression of NDRG1 was higher than those with low expression during the follow-up period. NDRG1 overexpression suppressed cells proliferation, invasion and induced a G1 cell cycle arrest in gastric cancer. Furthermore, the down-regulation of NDRG1 in gastric cancer metastatic progression was correlated to E-cadherin and MMP-9. Our results verify that NDRG1 acts as a tumor suppressor gene and may play an important role in the metastasis progression and prognosis of gastric cancer.     

MAPKs as a cross point in H2O2 and auxin signaling under combined cadmium and zinc stress in rice roots

Previously, we have reported the role of MAPKs (mitogen-activated protein kinases) under cadmium stress. This work continue to explore the relationship between MAPKs, H₂O₂, auxin signaling, and OsHMA and OsZIP gene expression in rice (Oryza sativa L.) roots under combined cadmium (Cd) and zinc (Zn) stress. Compared with Cd, Cd+Zn reduced Cd levels but increased Zn accumulation in the roots. Three OsMAPK genes were negatively regulated, while two OsHMA and two OsZIP genes were positively regulated by MAPK pathways under Cd+Zn stress. Transgenic rice expressing DR5-GUS exhibited enhanced GUS activity in H₂O₂-, PD (MAPKK inhibitor PD98059)-, or (Cd+Zn)-treated roots, which also exhibited increased H₂O₂ concentrations, whereas GUS staining decreased in roots in response to Cd+Zn+PD, DMTU (N,N′-dimethylthiourea, a H₂O₂ scavenger), or Cd+Zn+DMTU treatment, with reduced H₂O₂ levels. GUS levels were consistent with H₂O₂ levels, suggesting that MAPK pathway-mediated auxin redistribution occurs via H₂O₂, and H₂O₂ functions downstream of MAPK but upstream of auxin signaling pathways. Furthermore, MAPK pathways serve specific functions in regulating the expression of some key genes of auxin signaling (OsYUCCA, OsPIN, OsARF, and OsIAA) under Cd+Zn stress. Overall, MAPK cascades function in the integration of metal transport, H₂O₂ generation, and auxin signaling in rice seedlings grown under Cd+Zn stress.     

The neurobiological link between OCD and ADHD

Obsessive compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD) are two of the most common neuropsychiatric diseases in paediatric populations. The high comorbidity of ADHD and OCD with each other, especially of ADHD in paediatric OCD, is well described. OCD and ADHD often follow a chronic course with persistent rates of at least 40–50 %. Family studies showed high heritability in ADHD and OCD, and some genetic findings showed similar variants for both disorders of the same pathogenetic mechanisms, whereas other genetic findings may differentiate between ADHD and OCD. Neuropsychological and neuroimaging studies suggest that partly similar executive functions are affected in both disorders. The deficits in the corresponding brain networks may be responsible for the perseverative, compulsive symptoms in OCD but also for the disinhibited and impulsive symptoms characterizing ADHD. This article reviews the current literature of neuroimaging, neurochemical circuitry, neuropsychological and genetic findings considering similarities as well as differences between OCD and ADHD.     

Urokinase-type plasminogen activator receptor regulates apoptotic sensitivity of colon cancer HCT116 cell line to TRAIL via JNK-p53 pathway

The urokinase-type plasminogen activator receptor (uPAR) serves not only as an anchor for urokinase-type plasminogen activator but also participates in intracellular signal transduction events. In this study, we investigated whether uPAR could modulate TRAIL-induced apoptosis in human colon cancer cells HCT116. Using an antisense strategy, we established a stable HCT116 cell line with down-regulated uPAR. The sensitivity to TRAIL-induced apoptosis was evaluated by FACS analysis. Our results show that the inhibition of uPAR could sensitize HCT116 to TRAIL-induced apoptosis. uPAR inhibition changed the expression of mitochondrial apoptotic pathway proteins, including Bcl-2, Bax, Bid and p53, in a pro-apoptotic manner. We also found that the inhibition of uPAR down-regulated the phosphorylation of FAK, ERK and JNK. The inhibition of p53 by RNA interference rescued cells from enhanced apoptosis, thus indicating that p53 is critical for enhancing TRAIL-induced apoptosis. Furthermore, JNK, but not ERK, inhibition involved in the up-regulation of p53. JNK negatively regulated p53 protein level. Overall, our results show that uPAR inhibition can sensitize colon cancer cells HCT116 to TRAIL-induced apoptosis via active p53 and mitochondrial apoptotic pathways that JNK inhibition is involved.     

Estimates of heavy metal tolerance and chromium(VI) reducing ability of Pseudomonas aeruginosa CCTCC AB93066: chromium(VI) toxicity and environmental parameters optimization

The potential role of parameters in the reduction of hexavalent chromium [Cr(VI)] by Pseudomonas aeruginosa is not well documented. In this study, laboratory batch studies were conducted to assess the effect of a variety of factors, e.g., carbon sources, salinity, initial Cr(VI) concentrations, co-existing ions and a metabolic inhibitor, on microbial Cr(VI) reduction to Cr(III) by P. aeruginosa AB93066. Strain AB93066 tolerated up to 400 mg/L of Cr(VI) in nutrient broth medium compared to only 150 mg/L of Cr(VI) in nutrient agar. This bacteria exhibited different levels of resistance against Pb(II) (200 mg/L), Cd(II) (100 mg/L), Ni(II) (100 mg/L), Cu(II) (100 mg/L), Co(II) (50 mg/L) and Hg(II) (5 mg/L). Cr(VI) reduction was significantly promoted by the addition of glucose and glycerine but was strongly inhibited by the presence of methanol and phenol. The rate of Cr(VI) reduction increased with increasing concentrations of Cr(VI) and then decreased at higher concentrations. The presence of Ni(II) stimulated Cr(VI) reduction, while Pb(II), Co(II) and Cd(II) had adverse impact on reduction ability of this strain. Cr(VI) reduction was also inhibited by high levels of NaCl, various concentrations of sodium azide and 20 mM of SO₄ ^2?, MoO₄ ^2?, NO₃ ^?, PO₄ ^3?. No significant relationship was observed between Cr(VI) reduction and redox potential of the culture medium. Scanning electron microscopy showed visible morphological changes in the cells due to chromate stress. Fourier transform infrared spectroscopy analysis revealed chromium species was likely to form complexes with certain functional groups such as carboxyl and amino groups on the surface of P. aeruginosa AB93066. Overall, above results are beneficial to the bioremediation of chromate-polluted industrial wastewaters.