The role of duplication in the expression of a variable surface glycoprotein gene of Trypanosoma brucei

The variable surface glycoprotein (VSG) genes of Trypanosoma brucei have been classified into two groups depending upon whether or not duplication of the genes is observed when they are expressed. We report here the observation of duplication apparently linked to expression of the ILTaT 1.3 gene in the ETaR 1 trypanosome stock. In the ILTaR 1 stock, expression of the ILTaT 1.3 VSG did not involve a new duplication, but instead activation of a preexisting gene copy that had been apparently generated earlier by a duplication event analogous to that directly observed in the ETaR 1 trypanosomes. The results suggest that the well-characterised gene duplications found with other VSG genes are common to all VSG genes but are not directly responsible for controlling expression. All currently available data can be accommodated by a model that assumes that gene duplication and replacement occurs independently of antigenic switching.     

Virion conformational forms and the complex inactivation kinetics of echovirus by chlorine in water

Aberrant inactivation kinetics were observed when monodispersed echovirus type 1 (Farouk) was inactivated with chlorine. An initial 1- to 2-log10-unit decrease in titer was followed by lag period, during which the titer stayed the same or increased, and this was followed by a final decline in titer. First-order kinetics were obtained with poliovirus type 1 under the same conditions. Isoelectric focusing studies of echovirus before chlorine treatment showed that the virus distributed into two pH-dependent and interconvertible isoelectric forms. After chlorine treatment all remaining virus infectivity was associated with a third pH-independent isoelectric form. The complex inactivation kinetics appeared to be due to shifts between these conformational forms during inactivation in certain ionic environments. Under certain conditions the conformational shifts resulted in substantial resistance of monodispersed echovirus to chlorine.     

Interleukin-1-β and Tumor Necrosis Factor-α Increase Peripheral-Type Benzodiazepine Binding Sites in Cultured Polygonal Astrocytes

Peripheral-type benzodiazepine binding sites (PTBBS) are markedly increased in the injured CNS. Astrocytes appear to be the primary cell type which express increased PTBBS. Because certain cytokines within the injured CNS are potent mitogens for astrocytes, we examined the effects of two such cytokines, interleukin (IL)-1 beta and tumor necrosis factor (TNF), on PTBBS in cultured astrocytes using [3H]Ro 5-4864 as the specific ligand. Purified cultures of either polygonal or process-bearing astrocytes were prepared from neonatal rat cerebral hemispheres. At a concentration of 1.8 nM, specific binding of the radioactive ligand to polygonal astrocytes reached equilibrium within 60 min and was half-maximal by 5-10 min. By contrast, specific binding to process-bearing astrocytes barely exceeded background levels. IL-1 and TNF increased PTBBS within polygonal astrocytes in both dose- and time-dependent manners. At 10-50 ng/ml, IL-1 beta and TNF-alpha elevated [3H]Ro 5-4864 binding in polygonal astrocyte cultures 65 and 87%, respectively, above the level in control cultures. However, no changes in PTBBS were seen within polygonal astrocytes after IL-2 treatment. Scatchard analysis of saturation binding experiments suggested that the increase in PTBBS promoted by TNF was due to an increased number of binding sites present in polygonal astrocytes and not due to an increase in receptor affinity. Binding data suggested that PTBBS within cultures of process-bearing astrocytes were virtually absent irrespective of the treatment. These in vitro data suggest that certain cytokines found in the injured brain may be involved in up-regulating PTBBS within a particular subtype of astrocyte.     

Anti-Inflammatory Effects of Acupuncture Stimulation via the Vagus Nerve

Although acupuncture therapy is widely used in traditional Asian medicine for the treatment of diverse internal organ disorders, its underlying biological mechanisms are largely unknown. Here, we investigated the functional involvement of acupuncture stimulation (AS) in the regulation of inflammatory responses. TNF-α production in mouse serum, which was induced by lipopolysaccharide (LPS) administration, was decreased by manual acupuncture (MAC) at the zusanli acupoint (stomach36, ST36). In the spleen, TNF-α mRNA and protein levels were also downregulated by MAC and were recovered by using a splenic neurectomy and a vagotomy. c-Fos, which was induced in the nucleus tractus solitarius (NTS) and dorsal motor nucleus of the vagus nerve (DMV) by LPS and electroacupuncture (EAC), was further increased by focal administration of the AMPA receptor blocker CNQX and the purinergic receptor antagonist PPADS. TNF-α levels in the spleen were decreased by CNQX and PPADS treatments, implying the involvement of inhibitory neuronal activity in the DVC. In unanesthetized animals, both MAC and EAC generated c-Fos induction in the DVC neurons. However, MAC, but not EAC, was effective in decreasing splenic TNF-α production. These results suggest that the therapeutic effects of acupuncture may be mediated through vagal modulation of inflammatory responses in internal organs.     

Effect of Composition and Impurities on the Phosphorescence of Green-Emitting Alkaline Earth Aluminate Phosphor

Recent improvements to SrAl₂O₄:Eu²⁺, Dy³⁺ phosphors have enabled the use of luminescent hosts with a stable crystal structure and high physical and chemical stability, thus overcoming the bottleneck in the applicability of ZnS:Cu phosphors. However, enhancement of afterglow lifetime and brightness in SrAl₂O₄:Eu²⁺, Dy³⁺ phosphors remains a challenging task. Here, we have improved the afterglow characteristics in terms of persistence time and brightness by a systematic investigation of the composition of Eu-doped alkaline earth aluminate SrAl₂O₄:Eu²⁺, Dy³⁺ crystals. We found that a Dy³⁺/Eu²⁺ ratio of ~2.4 and ~0.935 mol Eu²⁺ (per mol of SrAl₂O₄) gave the brightest and longest emissions (11% and 9% increase for each). Doping with Si⁴⁺ also resulted in a slight increase in brightness up to ~15%. Doping with alkali metal or alkaline earth metal significantly enhanced the phosphorescence intensity. In particular, doping with 0.005 mol Li⁺ (per mol of SrAl₂O₄) alone boosted the phosphorescence intensity to 239% of the initial value, as compared to that observed for the non-doped crystal, while doping with 0.01 mol Mg²⁺ and 0.005 mol Li⁺ (per 1 mol SrAl₂O₄) boosted the phosphorescence intensity up to 313% of the initial value. The results of this investigation are expected to act as a guideline for the synthesis of bright and long persistent phosphors, and facilitate the development of persistent phosphors with afterglow characteristics superior to those of conventional phosphors.     

Secretion of Recombinant Pediocin PA-1 by Bifidobacterium longum, Using the Signal Sequence for Bifidobacterial α-Amylase

A recombinant DNA, encoding the chimeric protein of the signal sequence for bifidobacterial α-amylase mature pediocin PA-1, was introduced into Bifidobacterium longum MG1. Biologically active pediocin PA-1 was successfully secreted from the strain and showed bactericidal activity against Listeria monocytogenes and the same molecular mass as native pediocin PA-1.