Two cyanobacterial response regulators with diguanylate cyclase activity, Rre2 and Rre8, participate in biofilm formation.

Phototrophic bacteria face diurnal variations of environmental conditions such as light and osmolarity that affect their carbon metabolism and ability to generate organic compounds. The model cyanobacterium, Synechocystis sp. PCC 6803 forms a biofilm when it encounters extreme conditions like high salt stress, but the molecular mechanisms involved in perception of environmental changes that lead to biofilm formation are unknown. Here, we studied two two-component regulatory systems (TCSs) that contain diguanylate cyclases (DGCs), which produce the second messenger c-di-GMP, as potential components of the biofilm-inducing signaling pathway in Synechocystis. Analysis of single mutants provided evidence for involvement of the response regulators, Rre2 and Rre8 in biofilm formation. A bacterial two-hybrid assay showed that Rre2 and Rre8 each formed a TCS with a specific histidine kinase, Hik12 and Hik14, respectively. The in vitro assay showed that Rre2 had DGC activity regardless of its de/phosphorylation status, whereas Rre8 required phosphorylation for DGC activity. Hik14-Rre8 likely functioned as an inducible sensing system in response to environmental change. Biofilm assays with Synechocystis mutants suggested that pairs of hik12-rre2 and hik14-rre8 responded to high salinity-induced biofilm formation. Inactivation of hik12-rre2 and hik14-rre8 did not affect the performance of the light reactions of photosynthesis. These data suggest that Hik12-Rre2 and Hik14-Rre8 participate in biofilm formation in Synechocystis by regulating c-di-GMP production via the DGC activity of Rre2 and Rre8.

Effect of lutein on the acute inflammation-induced c-Fos expression of rat trigeminal spinal nucleus caudalis and C1 dorsal horn neurons.

Although lutein is known to inhibit chronic inflammation, its effect on acute inflammation-induced nociceptive processing in the trigeminal system remains to be determined. The aim of the present study was to investigate whether pretreatment with lutein attenuates acute inflammation-induced sensitization of nociceptive processing in rat spinal trigeminal nucleus caudalis (SpVc) and upper cervical (C1) dorsal horn neurons, via c-Fos immunoreactivity. Mustard oil, a transient receptor potential ankyrin-1 channel agonist, was injected into the whisker pads to induce inflammation. Pretreatment of rats with lutein resulted in significant decreases in the inflammation-induced mean times of face grooming and the thickness of inflammation-induced edema in whisker pads relative to those features in inflamed rats (i.e., rats with no lutein pretreatment). In both the ipsilateral superficial and deep laminae of the SpVc and C1 dorsal horn, there were significantly larger numbers of c-Fos-positive neurons in inflamed rats than in naïve rats, and lutein pretreatment significantly decreased that number relative to inflamed rats. These results suggest that systemic administration of lutein attenuates acute inflammation-induced nocifensive behavior and augmented nociceptive processing of SpVc and C1 neurons that send stimulus localization and intensity information to higher pain centers. These findings support lutein as a potential therapeutic agent for use as an alternative, complementary medicine to attenuate, or even prevent, acute inflammatory pain.

Effect of resveratrol on c-fos expression of rat trigeminal spinal nucleus caudalis and C1 dorsal horn neurons following mustard oil-induced acute inflammation.

The dietary constituent, resveratrol, was recently identified as a transient receptor potential ankyrin 1 (TRPA1) antagonist, voltage-dependent sodium ion (Na+ ) channel, and cyclooxygenase-2 (COX-2) inhibitor. The aim of the present study was to investigate whether pretreatment with resveratrol attenuates acute inflammation-induced sensitization of nociceptive processing in rat spinal trigeminal nucleus caudalis (SpVc) and upper cervical (C1) dorsal horn neurons, via c-fos immunoreactivity. Mustard oil (MO), a TRPA1 channel agonist, was injected into the whisker pads of rats to induce inflammation. Pretreatment with resveratrol significantly decreased the mean thickness of inflammation-induced edema in whisker pads compared with those of untreated, inflamed rats. Ipsilateral of both the superficial and deep laminae of SpVc and C1 dorsal horn, there were significantly more c-fos-immunoreactive SpVc/C1 neurons in inflamed rats compared with naïve rats, and resveratrol pretreatment significantly decreased that number relative to untreated, inflamed rats. These results suggest that systemic administration of resveratrol attenuates acute inflammation-induced augmented nociceptive processing of trigeminal SpVc and C1 neurons. These findings support resveratrol as a potential therapeutic agent for use in alternative, complementary medicine to attenuate, or even prevent, acute trigeminal inflammatory pain.

Folate-deficiency induced cell-specific changes in the distribution of lymphocytes and granulocytes in rats.

OBJECTIVE: Folate (vitamin B(9)) plays key roles in cell growth and proliferation through regulating the synthesis and stabilization of DNA and RNA, and its deficiency leads to lymphocytopenia and granulocytopenia. However, precisely how folate deficiency affects the distribution of a variety of white blood cell subsets, including the minor population of basophils, and the cell specificity of the effects remain unclear. Therefore, we examined the effects of a folate-deficient diet on the circulating number of lymphocyte subsets [T-lymphocytes, B-lymphocytes, and natural killer (NK) cells] and granulocyte subsets (neutrophils, eosinophils, and basophils) in rats. METHODS: Rats were divided into two groups, with one receiving the folate-deficient diet (FAD group) and the other a control diet (CON group). All rats were pair-fed for 8 weeks. RESULTS: Plasma folate level was dramatically lower in the FAD group than in the CON group, and the level of homocysteine in the plasma, a predictor of folate deficiency was significantly higher in the FAD group than in the CON group. The number of T-lymphocytes, B-lymphocytes, and NK cells was significantly lower in the FAD group than in the CON group by 0.73-, 0.49-, and 0.70-fold, respectively, indicating that B-lymphocytes are more sensitive to folate deficiency than the other lymphocyte subsets. As expected, the number of neutrophils and eosinophils was significantly lower in the FAD group than in the CON group. However, the number of basophils, the least common type of granulocyte, showed transiently an increasing tendency in the FAD group as compared with the CON group. CONCLUSION: These results suggest that folate deficiency induces lymphocytopenia and granulocytopenia in a cell-specific manner.

Diallyl disulfide reduced dose-dependently the number of lymphocyte subsets and monocytes in rats.

Diallyl disulfide (DADS) is a major sulfur compound of garlic, and exerts anti-inflammatory, immune-modulatory, and enhancing sympathetic activity effects. However, it still remains unclear how DADS affects the distribution of white blood cell subsets, which is essential to execute effective immune responses and partially regulated by adrenal glucocorticoids. Therefore, we examined the dose-dependent effects of DADS administration on the circulating number of white blood cells (WBCs) and lymphocyte subsets, and plasma corticosterone concentration in rats. Male 10-wk-old Sprague Dawley rats were divided into the DADS-free and DADS-orally administered (dose=10, 20, and 40 mg/kg BW) groups. Blood samples were collected from the tail vein at 0, 1, 2, 4, and 6 h after the administration. DADS administration decreased dose- and time-dependently the circulating number of total WBCs, total lymphocytes, and monocytes. Within the lymphocyte subsets, the circulating number of T-lymphocytes and B-lymphocytes was significantly reduced 4 h after DADS administration in a dose-dependent manner, although that of natural killer (NK) cells was not affected. On the other hand, although DADS administration did not significantly change the circulating number of neutrophils, the circulating number of eosinophils and basophils showed a decreasing tendency after DADS administration. In contrast, plasma corticosterone concentration was increased 2 h after DADS administration in a dose-dependent manner. These results suggest that DADS administration reduces the circulating number of monocytes and lymphocytes, including especially acquired immune cells, via the action of corticosterone, and the effects are induced in a dose-dependent manner.