Heme oxygenase is involved in nitric oxide- and auxin-induced lateral root formation in rice

Lateral root (LR) development performs the essential tasks of providing water, nutrients, and physical support to plants. Therefore, understanding the regulation of LR development is of agronomic importance. In this study, we examined the effect of nitric oxide (NO), auxin, and hemin (Hm) on LR formation in rice. Treatment with Hm [a highly effective heme oxygenase (HO) inducer], sodium nitroprusside (SNP, an NO donor), or indole-3-butyric acid (IBA, a naturally occurring auxin) induced LR formation and HO activity. LR formation and HO activity induced by SNP and IBA but not Hm was reduced by the specific NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide. As well, Hm, SNP, and IBA could induce OsHO1 mRNA expression. Zn protoporphyrin IX (the specific inhibitor of HO) and hemoglobin (the carbon monoxide/NO scavenger) reduced LR number and HO activity induced by Hm, SNP, and IBA. Our data suggest that HO is required for Hm-, auxin-, and NO-induced LR formation in rice.     

Isolation of single-site Escherichia coli mutants deficient in thiamine and 4-thiouridine syntheses: identification of a nuvC mutant

A method is described to rapidly select and classify many independent near-UV irradiation-resistant Escherichia coli mutants, which include tRNA modification and RNA synthesis control mutants. One class of these mutants was found to be simultaneously deficient in thiamine biosynthesis and in the ability to modify uridine in tRNA to 4-thiouridine, known to be the target for near-UV irradiation. These mutants were found to be unable to make thiazole, a thiamine precursor. The addition of thiazole restores the thiamine deficiency but does not render the cells near-UV irradiation sensitive. In vitro studies on one of these mutants indicated a deficiency in protein factor C (nuvC), required for the 4-thiouridine modification of tRNA. In P1 transduction, the thiazole marker cotransduced with the histidine marker, which places the thiazole marker between 42 and 46 min on the E. coli chromosome map. Both thiamine production and 4-thiouridine production were resumed by 87% of the spontaneous reversions, suggesting a single-point mutation. Our results indicate that we have isolated nuvC mutants and that the nuvC polypeptide is involved in two functions, tRNA modification and thiazole biosynthesis.     

Circuit for the electromanipulation of plant protoplasts

An electric circuit for plant protoplast manipulation is described. The circuit used readily available materials and was designed for use in teaching. This integrated circuit can be placed in a single small box with controls for the aligning voltage, the aligning frequency, the pulse voltage, and the pulse timing. The circuit can be supplied by any suitable source of dc power and can be easily altered for individual requirements. The circuit, as presented here, can be assembled for less than $250.     

An unlabeled antibody macromolecule technique using hemocyanin for the identification of type B and type C retrovirus envelope and cell surface antigens by correlative fluorescence, transmission electron, and scanning electron microscopy.

The present resolution (75-100 A) of the conventional scanning electron microscope (SEM) and its ability to image the surfaces of large numbers of whole cells in situ permit the approach of problems such as viral and cell surface antigen localization by immunological labeling with visual markers. Identification of virus and cell surface antigens in situ has been accomplished in indirect reactions by unconjugated markers. Hemocyanin (Hcy) from whelk, Busycon canniculatum, has been developed as an immunospecific marker for virion and cell surface labeling in the electron microscope. Its size (30 x 50 nm) and distinct cylindrical shape permit easy visualization in the SEM and the transmission electron microscope (TEM). The Hcy method involves the preparation of antisera to Hcy in appropriate hosts for use in an unlabeled antibody macromolecule procedure based exclusively on antigen-antibody affinity to couple the macromolecule to the antigen site. Further correlative data from fluorescence microscopy can be obtained from similarly labeled samples by binding fluorescein to the bridging antibodies used in the Hcy technique. The usefulness of the Hcy marker system was demonstrated by employing highly specific antisera to the major envelope and cell surface glycoprotein (gp70) of Rauscher murine leukemia virus (R-MuLV), a type C retrovirus. The antiserum was shown to bind to the virion and cell surfaces of virus-infected cells in the homologous virus-infected cell system. It also demonstrated the expression of R-MuLV gp70-related antigens on a murine cell line Mm5mt/c1 which produces mouse mammary tumor virus (MuMTV), a type B retrovirus. Furthermore, when used in the Hcy marker system the anti-gp70 serum was able to distinguish type B from type C budding virus on the same cell. Methods for the preparation of immunoreagents and labeling of cells are discussed.     

Mechanisms for inhibition of hepatitis B virus gene expression and replication by hepatitis C virus core protein

We have demonstrated previously that the core protein of hepatitis C virus (HCV) exhibits suppression activity on gene expression and replication of hepatitis B virus (HBV). Here we further elucidated the suppression mechanism of HCV core protein. We demonstrated that HCV core protein retained the inhibitory effect on HBV gene expression and replication when expressed as part of the full length of HCV polyprotein. Based on the substitution mutational analysis, our results suggested that mutation introduced into the bipartite nuclear localization signal of the HCV core protein resulted in the cytoplasmic localization of core protein but did not affect its suppression ability on HBV gene expression. Mutational studies also indicated that almost all dibasic residue mutations within the N-terminal 101-amino acid segment of the HCV core protein (except Arg(39)-Arg(40)) impaired the suppression activity on HBV replication but not HBV gene expression. The integrity of Arg residues at positions 101, 113, 114, and 115 was found to be essential for both suppressive effects, whereas the Arg residue at position 104 was important only in the suppression of HBV gene expression. Moreover, our results indicated that the suppression on HBV gene expression was mediated through the direct interaction of HCV core protein with the trans-activator HBx protein, whereas the suppression of HBV replication involved the complex formation between HBV polymerase (pol) and the HCV core protein, resulting in the structural incompetence for the HBV pol to bind the package signal and consequently abolished the formation of the HBV virion. Altogether, this study suggests that these two suppression effects on HBV elicited by the HCV core protein likely depend on different structural context but not on nuclear localization of the core protein, and the two effects can be decoupled as revealed by its differential targets (HBx or HBV pol) on these two processes of the HBV life cycle.     

Mechanobiological dysregulation of the epidermis and dermis in skin disorders and in degeneration

During growth and development, the skin expands to cover the growing skeleton and soft tissues by constantly responding to the intrinsic forces of underlying skeletal growth as well as to the extrinsic mechanical forces from body movements and external supports. Mechanical forces can be perceived by two types of skin receptors: (1) cellular mechanoreceptors/mechanosensors, such as the cytoskeleton, cell adhesion molecules and mechanosensitive (MS) ion channels, and (2) sensory nerve fibres that produce the somatic sensation of mechanical force. Skin disorders in which there is an abnormality of collagen [e.g. Ehlers–Danlos syndrome (EDS)] or elastic (e.g. cutis laxa) fibres or a malfunction of cutaneous nerve fibres (e.g. neurofibroma, leprosy and diabetes mellitus) are also characterized to some extent by deficiencies in mechanobiological processes. Recent studies have shown that mechanotransduction is crucial for skin development, especially hemidesmosome maturation, which implies that the pathogenesis of skin disorders such as bullous pemphigoid is related to skin mechanobiology. Similarly, autoimmune diseases, including scleroderma and mixed connective tissue disease, and pathological scarring in the form of keloids and hypertrophic scars would seem to be clearly associated with the mechanobiological dysfunction of the skin. Finally, skin ageing can also be considered as a degenerative process associated with mechanobiological dysfunction. Clinically, a therapeutic strategy involving mechanoreceptors or MS nociceptor inhibition or acceleration together with a reduction or augmentation in the relevant mechanical forces is likely to be successful. The development of novel approaches such as these will allow the treatment of a broad range of cutaneous diseases.     

EGF upregulates Na+/H+ exchanger NHE1 by post-translational regulation that is important for cervical cancer cell invasiveness

Na+/H+ exchanger 1 (NHE1) is involved in cell migration but little is known about the signal pathways that regulate NHE1 activity and that are associated with tumor cell invasiveness. This study is to investigate the mechanisms by which epidermal growth factor (EGF) regulates NHE1 expression to promote cervical cancer cell invasiveness and the clinical significance in early-stage cervical cancer. NHE1 protein was scanty in normal or noncancerous cervical tissues of all surgical specimens examined (n = 92). Tumor tissues clearly expressed NHE1 protein with different amounts. The differential expression level of NHE1 is associated with the clinical outcome. NHE1 protein was also differentially expressed between normal cervical epithelial cells and two cervical cancer cell lines. Cervical cancer cells benefit some enhanced cellular functions from NHE1 abundance, such as cell volume regulation, migration, and invasion. Interestingly, NHE1 colocalized with EGF in cervical cancer tissues. Studies in cell culture systems indicated that EGF-stimulated NHE1 abundance in a time-dependent manner by post-translational regulation. This implies a likely autocrine or paracrine EGF stimulation of NHE1 production in vivo. In addition, the phosphoinositide 3-kinase pathway is the dominant signal controlling EGF-stimulated NHE1 abundance. Pharmacological inhibition of NHE1 activity markedly inhibited the basal and EGF-stimulated cervical cancer cell migration. Image studies and immunoprecipitaion experiments suggest that EGF-induced NHE1 translocation to the leading-edge lamellipodia, where NHE1 interacted with actin-associated protein Ezrin, thereby remodeling cytoskeleton and stimulating cervical cancer cell migration. In conclusion, EGF upregulates NHE1 by post-translational regulation that is important for cervical cancer cell invasiveness.     

N-3 polyunsaturated fatty acids decrease levels of doxorubicin-induced reactive oxygen species in cardiomyocytes -- involvement of uncoupling protein UCP2

Background

Use of the chemotherapeutic drug doxorubicin (DOX) is associated with serious cardiotoxicity, as it increases levels of reactive oxygen species (ROS). N-3 polyunsaturated fatty acid dietary supplements can be of benefit to patients undergoing cancer therapy. The aims of this study were to determine whether DOX-induced cardiotoxicity is related to mitochondrial uncoupling proteins and whether eicosapentaenoic acid (EPA, C20:5 n-3) or docosahexaenoic acid (DHA, C22:6 n-3) affects DOX-induced cardiomyocyte toxicity.

Results

Treatment of H9C2 cells with DOX resulted in decreased cell viability and UCP2 expression. Treatment with 100 μM EPA or 50 μM DHA for 24 h resulted in a maximal mitochondria concentration of these fatty acids and increased UCP2 expression. Pretreatment with 100 μM EPA or 50 μM DHA prevented the DOX-induced decrease in UCP2 mRNA and protein levels, but these effects were not seen with EPA or DHA and DOX cotreatment. In addition, the DOX-induced increase in ROS production and subsequent mitochondrial membrane potential change (∆ψ) were significantly attenuated by pretreatment with EPA or DHA.

Conclusion

EPA or DHA pre-treatment inhibits the DOX-induced decrease in UCP2 expression, increase in ROS production, and subsequent mitochondrial membrane potential change that contribute to the cardiotoxicity of DOX.

Electronic supplementary material

The online version of this article (doi:10.1186/s12929-014-0101-3) contains supplementary material, which is available to authorized users.