Effect of dexmedetomidine on the release of [3H]-noradrenaline from rat kidney cortex slices: characterization of alpha2-adrenoceptor

The presynaptic modulation of [3H]-noradrenaline (NA) release from rat kidney cortex slices, a method used for the first time, was investigated. Rat kidney cortex slices were loaded with [3H]-NA and the release of radioactivity at rest and in response to field stimulation was determined. The alpha(2)-adrenoceptor agonist, dexmedetomidine inhibited the stimulation-evoked release of NA from kidney slices in a concentration-dependent manner, whereas alpha(2)-adrenoceptor antagonist CH-38083 (7,8-methyenedioxy-14-alpha-hydroxyalloberbane HCl), an alpha(2)-adrenoceptor antagonists, enhanced it. When dexmedetomidine and BRL-44408, a selective alpha(2A) antagonist, were added together, the effect of dexmedetomidine was significantly antagonized. In contrast, ARC-239 (2-(2,4-(o-piperazine-1-yl)-ethyl-4,4-dimethyl-1,3-(2H, 4H)disoguinolinedione chloride), a selective alpha(2B)-antagonist, had no effect on the release and failed to prevent the effect of dexmedetomidine. Prazosin, an alpha(1)- and alpha(2B/C)-adrenoceptor antagonist enhanced the release evoked by field stimulation. It is therefore suggested that there is a negative feedback modulation of NA release at the sympathetic innervation of kidney cortex, and dexmedetomidine, a clinically used anesthetic adjunct inhibits the release via activation of alpha(2C)-adrenoceptors.     

Formation of functionally active chloroplasts is determined at a limited stage of leaf development in virescent mutants of rice

The ability to form functionally active chloroplasts is determined at a certain early stage of leaf development in three non-allelic temperature-sensitive virescent mutants of rice. Temperature-shift analysis, together with anatomical observations, indicates that the intrinsic developmental signals of the virescent genes are expressed at the stage immediately following the formation of basic leaf structure, but just before the onset of leaf elongation. These signals control the expression of chloroplast-encoded genes but do not affect the subsequent morphological development of the leaf or the photo-regulation of the expression of nuclear genes encoding chloroplast proteins.     

Kidney proteome responses in the teleost fish Paralichthys olivaceus indicate a putative immune response against Streptococcus parauberis

The proteomic response to bacterial infection in a teleost fish (Paralichthys olivaceus) infected with Streptococcus parauberis was analyzed using label-free protein quantitation coupled with LC-MS(E) tandem mass spectrometry. A total of 82 proteins from whole kidney, a major lymphoid organ in this fish, were found to be differentially expressed between healthy and diseased fish analyzed 6, 24, 72 and 120 h post-infection. Among the differentially expressed proteins, those involved in mediating immune responses (e.g., heat shock proteins, cathepsins, goose-type lysozyme and complement components) were most significantly up-regulated by infection. In addition, cell division cycle 48 (CDC48) and calreticulin, which are associated with cellular recovery and glycoprotein synthesis, were up-regulated in the universal protein group, whereas the other proteins in that group were down-regulated. There was continuous activation of expression of immune-associated proteins during infection, but there was also loss of expression of proteins not involved in immune function. We expect that our findings regarding immune response at the protein level would offer new insight into the systemic response to bacterial infection of a major immune organ in teleost fish.     

Secreted Nucleobindin-2 Inhibits 3T3-L1 Adipocyte Differentiation

Nucleobindin-2 is a 420 amino acid EF-hand Ca2+ binding protein that can be further processed to generate an 82 amino terminal peptide termed Nesfatin-1. To examine the function of secreted Nucleobindin-2 in adipocyte differentiation, cultured 3T3-L1 cells were incubated with either 0 or 100 nM of GST, GST-Nucleobindin-2, prior to and during the initiation of adipocyte differentiation. Nucleobindin-2 treatment decreased neutral lipid accumulation (Oil-Red O staining) and expression of several marker genes for adipocyte differentiation (PPARγ, aP2, and adipsin). When Nucleobindin- 2 was constitutively secreted into cultured medium, cAMP content and insulin stimulated CREB phosphorylation were significantly reduced. On the other hand, intracellularly overexpressed Nucleobindin-2 failed to affect cAMP content and CREB phosphorylation. Taken together, these data indicate that secreted Nucleobindin-2 is a suppressor of adipocyte differentiation through inhibition of cAMP production and insulin signal.     

Fine root turnover of Japanese white birch (<Emphasis Type="Italic">Betula platyphylla</Emphasis> var. <Emphasis Type="Italic">japonica</Emphasis>) grown under elevated CO<Subscript>2</Subscript> in northern Japan

Key message

Elevated CO ₂ reduced fine root dynamics (production and turnover) of white birch seedlings, especially grown in volcanic ash soil compared with brown forest soil.

Abstract

Increased atmospheric CO₂ usually enhances photosynthetic ability and growth of trees. To understand how increased CO₂ affects below-ground part of trees under varied soil condition, we investigated the responses of the fine root (diameter <2 mm) dynamics of Japanese white birch (Betula platyphylla var. japonica) which was planted in 2010. The three-year-old birch seedlings were grown in four experimental treatments comprising two levels of CO₂, i.e., ambient: 380–390 and elevated: 500 μmol mol^?1, in combination with two kinds of soil: brown forest (BF) soil and volcanic ash (VA) soil which has few nutrients. The growth and turnover of fine roots were measured for 3 years (2011–2013) using the Mini-rhizotron. In the first observation year, live fine root length (standing crop) in BF soil was not affected by CO₂ treatment, but it was reduced by the elevated CO₂ from the second observation year. In VA soil, live fine root length was reduced by elevated CO₂ for all 3 years. Fine root turnover tended to decrease under elevated CO₂ compared with ambient in both soil types during the first and second observation years. Turnover of fine root production and mortality was also affected by the two factors, elevated CO₂ and different soil types. Median longevity of fine root increased under elevated CO₂, especially in VA soil at the beginning, and a shorter fine root lifespan appeared after 2 years of observation (2011–2012). These results suggest that elevated CO₂ does not consistently stimulate fine root turnover, particularly during the plant seedlings stage, as it may depend on the costs and benefits of constructing and retaining roots. Therefore, despite the other uncontrollable environment factors, carbon sequestration to the root system may be varied by CO₂ treatment period, soil type and plant age.

     

Intratracheal immunization with pili protein protects against mortality associated with Pseudomonas aeruginosa pneumonia in mice

We examined the protective effect of intratracheal immunization with Pseudomonas aeruginosa pili protein against respiratory infection caused by P. aeruginosa. Mice were immunized intratracheally or subcutaneously with purified pili protein or bovine serum albumin as a control. Intratracheally but not subcutaneously pili protein-immunized mice showed significant improvement of survival after intratracheal challenge with the PAO1 strain. Furthermore, bacterial cell counts in pili protein-immunized murine lungs were significantly decreased compared to controls at 18 h after the challenge. Antipili protein antibody titers in bronchoalveolar lavage fluid of intratracheally pili protein-immunized mice were higher than in bovine serum albumin immunized mice. However, antipili antibody titers were not increased in bronchoalveolar lavage fluid of subcutaneously pili protein-immunized mice, despite the high serum antipili antibody titers. Inoculation of P. aeruginosa induced immediate increases in interleukin-12 and interferon-gamma in bronchoalveolar lavage fluid of pili protein-immunized mice, reflecting an adequate and rapid immune response against P. aeruginosa respiratory tract infection. Our findings suggest that intratracheal pili protein immunization is effective against respiratory tract infection caused by P. aeruginosa in mice.     

Repression of tax expression is associated both with resistance of human T-cell leukemia virus type 1-infected T cells to killing by tax-specific cytotoxic T lymphocytes and with impaired tumorigenicity in a rat model

Human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia (ATL). Although the viral transactivation factor, Tax, has been known to have apparent transforming ability, the exact function of Tax in ATL development is still not clear. To understand the role of Tax in ATL development, we introduced short-interfering RNAs (siRNAs) against Tax in a rat HTLV-1-infected T-cell line. Our results demonstrated that expression of siRNA targeting Tax successfully downregulated Tax expression. Repression of Tax expression was associated with resistance of the HTLV-1-infected T cells to Tax-specific cytotoxic-T-lymphocyte killing. This may be due to the direct effect of decreased Tax expression, because the Tax siRNA did not alter the expression of MHC-I, CD80, or CD86. Furthermore, T cells with Tax downregulation appeared to lose the ability to develop tumors in T-cell-deficient nude rats, in which the parental HTLV-1-infected cells induce ATL-like lymphoproliferative disease. These results indicated the importance of Tax both for activating host immune response against the virus and for maintaining the growth ability of infected cells in vivo. Our results provide insights into the mechanisms how the host immune system can survey and inhibit the growth of HTLV-1-infected cells during the long latent period before the onset of ATL.     

A new UV method for serum gamma-glutamyltransferase assay using recombinant 4-aminobenzoate hydroxylase as a coupling enzyme.

4-aminobenzoate hydroxylase (4ABH) is a flavin-dependent monooxygenase that catalyzes the decarboxylative hydroxylation of 4-aminobenzoate to 4-hydroxyaniline. For use as a clinical reagent, the gene encoding 4ABH from Agaricus bisporus was cloned by the RACE method. Also, the cDNA encoding 4ABH was expressed in Escherichia coli cells as a fusion protein with glutathione S-transferase (GST). The expressed GST-4ABH fusion protein (recombinant 4ABH) in the soluble fraction exhibits decarboxylative hydroxylation and additional NADH oxidation activities.We investigated a new ultraviolet spectrometric method for determining serum gamma-glutamyltransferase (gamma-GT) using recombinant 4ABH as a coupling enzyme. The principle of the method is as follows. Using gamma-glutamyl-3-choloro-4-aminobenzoate (L-gamma-glu-PAClBA) and glycylglycine as the donor and acceptor substrates, 3-choloro-4-aminobenzoate (PAClBA) is formed by the catalysis of serum gamma-GT. PAClBA is stoichiometrically converted to 3-choloro-4-hydroxyaniline (PHClA) and NAD(+) by 4ABH and NADH. However, NADH oxidation results in a high reagent blank, which is considered as a drawback for use as a clinical reagent.Using recombinant 4ABH, we examined the effects of pH and detergents on these two activities, and found that several detergents suppress the additional NADH oxidation activity with little or no effect on hydroxylation activity. The results indicate a promising approach to establishing an ultraviolet spectrophotometric method for determining serum gamma-GT activity using L-gamma-glu-PAClBA as the donor substrate and recombinant 4ABH as a coupling enzyme.