Halorubrum halophilum sp. nov., an extremely halophilic archaeon isolated from a salt-fermented seafood

A novel, red-pigmented, pleomorphic and short rod-shaped haloarchaeon, designated B8^T, was isolated from a salt-fermented seafood. Strain B8^T was found to be able to grow at 20–45 °C, in the presence of 15–30 % (w/v) NaCl and at pH 7.0–9.0. The optimum requirements were found to be a temperature range of 35–40 °C, pH 8.0 and the presence of 25 % NaCl. The cells of strain B8^T were observed to be Gram-staining negative and lysed in distilled water. Anaerobic growth did not occur in the presence of nitrate, l-arginine, dimethyl sulfoxide or trimethylamine N-oxide. The catalase and oxidase activities were found to be positive and nitrate was reduced in aerobic conditions. Tween 20, 40 and 80 were found to be hydrolyzed, whereas casein, gelatin and starch were not hydrolyzed. Indole or H₂S was not formed and urease activity was not detected. A phylogenetic analysis based on the 16S rRNA gene sequences indicated that strain B8^T is most closely related to members of the genus Halorubrum in the family Halobacteriaceae. Strain B8^T was found to have three 16S rRNA genes, rrnA, rrnB and rrnC; similarities between the 16S rRNA gene sequences are 99.0–99.8 %. Strain B8^T shared 99.0 % 16S rRNA gene sequence similarity with Halorubrum (Hrr.) lipolyticum JCM 13559^T and Hrr. saccharovorum DSM 1137^T, 98.8 % with Hrr. kocurii JCM 14978^T, 98.3 % with Hrr. lacusprofundi DSM 5036^T, 98.0 % with Hrr. arcis JCM 13916^T, 97.7 % with Hrr. aidingense JCM 13560^T and 97.0 % with Hrr. aquaticum JCM 14031^T, as well as 93.7–96.5 % with other type strains in the genus Halorubrum. The RNA polymerase subunit B′ gene sequence similarity of strain B8^T with Hrr. kocurii JCM 14978^T is 97.2 % and lower with other members of the genus Halorubrum. DNA–DNA hybridization experiments showed that strain B8^T shared equal or lower than 50 % relatedness with reference species in the genus Halorubrum. The genomic DNA G+C content of strain B8^T was determined to be 64.6 mol%. The major isoprenoid quinone of strain B8^T was identified as menaquinone-8 and the major polar lipids as phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate, sulfated mannosyl glucosyl diether and an unidentified phospholipid. Based on this polyphasic taxonomic study, strain B8^T is considered to represent a new species in the genus Halorubrum, for which the name Hrr. halophilum sp. nov. is proposed. The type strain is B8^T (=JCM 18963^T = CECT 8278^T).     

Hilar GABAergic interneuron activity controls spatial learning and memory retrieval

Background

Although extensive research has demonstrated the importance of excitatory granule neurons in the dentate gyrus of the hippocampus in normal learning and memory and in the pathogenesis of amnesia in Alzheimer''s disease (AD), the role of hilar GABAergic inhibitory interneurons, which control the granule neuron activity, remains unclear.

Methodology and Principal Findings

We explored the function of hilar GABAergic interneurons in spatial learning and memory by inhibiting their activity through Cre-dependent viral expression of enhanced halorhodopsin (eNpHR3.0)—a light-driven chloride pump. Hilar GABAergic interneuron-specific expression of eNpHR3.0 was achieved by bilaterally injecting adeno-associated virus containing a double-floxed inverted open-reading frame encoding eNpHR3.0 into the hilus of the dentate gyrus of mice expressing Cre recombinase under the control of an enhancer specific for GABAergic interneurons. In vitro and in vivo illumination with a yellow laser elicited inhibition of hilar GABAergic interneurons and consequent activation of dentate granule neurons, without affecting pyramidal neurons in the CA3 and CA1 regions of the hippocampus. We found that optogenetic inhibition of hilar GABAergic interneuron activity impaired spatial learning and memory retrieval, without affecting memory retention, as determined in the Morris water maze test. Importantly, optogenetic inhibition of hilar GABAergic interneuron activity did not alter short-term working memory, motor coordination, or exploratory activity.

Conclusions and Significance

Our findings establish a critical role for hilar GABAergic interneuron activity in controlling spatial learning and memory retrieval and provide evidence for the potential contribution of GABAergic interneuron impairment to the pathogenesis of amnesia in AD.     

Rubrioxytricha guamensis nov. spec. (Ciliophora,Spirotricha), a Novel Hypotrich Ciliate from Guam (United States), Micronesia

The oxytrichid ciliate Rubrioxytricha guamensis nov. spec. isolated from water samples collected from a small freshwater pond near the Hagåtña River in Hagåtña, Guam (United States territory), Micronesia, was investigated, using live observation and protargol impregnation. The morphology, ontogenesis, and molecular phylogeny inferred from the small‐subunit rRNA gene sequences were studied. The new species is mainly characterized by a cell size of about 100 × 35 μm in vivo, two elongate ellipsoidal macronuclear nodules and two micronuclei, a single contractile vacuole, a colorless cytoplasm, yellowish cortical granules, arranged in short rows and in small groups, an adoral zone occupying about 34% of body length and comprising 27 membranelles on average, about 27 cirri each in the right and left marginal rows, 18 frontoventral transverse cirri, four dorsal kineties including one dorsomarginal row, and one or two caudal cirri at the posterior end of dorsal kinety 3. The ontogenesis of the new species is similar to that of Rubrioxytricha indica Naqvi et al., 2006. Phylogenetic analyses based on SSU rRNA gene sequences consistently place the new species within the family Oxytrichidae Ehrenberg, 1838, where it clustered with other Rubrioxytricha species, viz., R. tsinlingensis, R. ferruginea, and R. haematoplasma.     

Synthesis and characterization of sugar-bearing chitosan derivatives: aqueous solubility and biodegradability

The extended use of chitosan in biomedical fields has been limited by its insoluble nature in a biological solution. To endow the water solubility in a broad range of pH, chitosan derivatives were prepared by the covalent attachment of a hydrophilic sugar moiety, gluconic acid, through the formation of an amide bond. These sugar-bearing chitosans (SBCs) were further modified by the N-acetylation in an alcoholic aqueous solution. Thereafter, the effect of the gluconyl group and the degree of N-acetylation (DA) on the water solubility at different pHs and on the biodegradability of chitosan were investigated. The SBCs showed the water solubility in a broader range of pH than chitosan, whereas they were still insoluble at neutral and alkali pH. The N-acetylation of SBCs significantly affected the water solubility, for example, the SBCs with the DA, ranging from 29% to 63%, were soluble in the whole range of pH. This might result from the improved hydrophilicity by the gluconyl group, accompanied by the role of the N-acetyl group that disturbed the hydrogen bonding between amino groups of chitosan. From the biodegradation tests, determined by the decrease in the viscosity of a polymer solution exposed to lysozyme, it was evident that the gluconyl group attached to chitosan improved the biodegradability. Thus, it was possible to control the biodegradability of chitosan by adjusting the amounts of gluconyl and N-acetyl groups in the chitosan backbone. The N-acetylated SBCs, soluble in the broad range of pH, might be useful for various biomedical applications.     

Synthesis of Poly(N-isopropylacrylamide) Janus Microhydrogels for Anisotropic Thermo-responsiveness and Organophilic/Hydrophilic Loading Capability

Janus microparticles are compartmentalized particles with differing molecular structures and/or functionality on each of their two sides. Because of this unique property, Janus microparticles have been recognized as a new class of materials, thereby attracting a great deal of attention from various research fields. The versatility of these microparticles has been exemplified through their uses as building blocks for self-assembly, electrically responsive actuators, emulsifiers for painting and cosmetics, and carriers for drug delivery. This study introduces a detailed protocol that explicitly describes a synthetic method for designing novel Janus microhydrogels composed of a single base material, poly(N-isopropylacrylamide) (PNIPAAm). Janus microdroplets are firstly generated via a hydrodynamic focusing microfluidic device (HFMD) based on the separation of a supersaturated aqueous NIPAAm monomer solution and subsequently polymerized through exposure to UV irradiation. The resulting Janus microhydrogels were found to be entirely composed of the same base material, featured an easily identifiable compartmentalized morphology, and exhibited anisotropic thermo-responsiveness and organophilic/hydrophilic loading capability. We believe that the proposed method introduces a novel hydrogel platform with the potential for advanced synthesis of multi-functional Janus microhydrogels.     

Modulation of catalase in human skin in vivo by acute and chronic UV radiation.

In this study, we demonstrate that catalase is differently regulated either by acute, or chronic UV radiation during the photoaging process. 2MED of UV radiation decreased the activity and expression of catalase gradually in the epidermis and dermis at between 24 and 48 h after the UV exposure. These levels then returned to near normal by 72 h after exposure. The catalase mRNA was also decreased in the skin 24 h after UV irradiation to 50% of the control level, and then started to recover. In contrast, chronic UV irradiation over a lifetime (approximately 50 years) increased the catalase activity in the epidermis and dermis of the human skin in vivo. Our results suggest that catalase might be one of the important enzymes in the skin aging process, and that it plays an important role in the photoprotection of the skin from UV light.     

Syntheses and anti-MRSA activities of the C3 analogs of mansonone F, a potent anti-bacterial sesquiterpenoid: insights into its structural requirements for anti-MRSA activity

Syntheses and excellent anti-MRSA activities of the mansonone F analogs are reported. In addition, the minimal structural requirements for its anti-MRSA activities as well as its structure-activity relationship including the C3 substituents effects on anti-MRSA activity are also described. In particular, this study revealed that both ortho-quinone and tricyclic systems of mansonone F are essential for anti-MRSA activities.     

Batch and fed-batch production of coenzyme Q10 in recombinant Escherichia coli containing the decaprenyl diphosphate synthase gene from Gluconobacter suboxydans

Coenzyme Q₁₀ (CoQ₁₀) is a quinine consisting of ten units of the isoprenoid side-chain. Because it limits the oxidative attack of free radicals to DNA and lipids, CoQ₁₀ has been used as an antioxidant for foods, cosmetics and pharmaceuticals. Decaprenyl diphosphate synthase (DPS) is the key enzyme for synthesis of the decaprenyl tail in CoQ₁₀ with isopentenyl diphosphate. The ddsA gene coding for DPS from Gluconobacter suboxydans was expressed under the control of an Escherichia coli constitutive promoter. Analysis of the cell extract in recombinant E. coli BL21/pACDdsA by high performance liquid chromatography and mass spectrometry showed that CoQ₁₀ rather than endogenous CoQ₈ was biologically synthesized as the major coenzyme Q. Expression of the ddsA gene with low copy number led to the accumulation of CoQ₁₀ to 0.97 mg l^–1 in batch fermentation. A high cell density (103 g l^–1) in fed-batch fermentation of E. coli BL21/pACDdsA increased the CoQ₁₀ concentration to 25.5 mg l ^–1 and its productivity to 0.67 mg l^–1 h^–1, which were 26.0 and 6.9 times higher than the corresponding values for batch fermentation.