Macrophages overexpressing tartrate-resistant acid phosphatase show altered profile of free radical production and enhanced capacity of bacterial killing

Activated macrophages and osteoclasts express high amounts of tartrate-resistant acid phosphatase (TRACP, acp5). TRACP has a binuclear iron center with a redox-active iron that has been shown to catalyze the formation of reactive oxygen species (ROS) by Fenton’s reaction. Previous studies suggest that ROS generated by TRACP may participate in degradation of endocytosed bone matrix products in resorbing osteoclasts and degradation of foreign compounds during antigen presentation in activated macrophages. Here we have compared free radical production in macrophages of TRACP overexpressing (TRACP+) and wild-type (WT) mice. TRACP overexpression increased both ROS levels and superoxide production. Nitric oxide production was increased in activated macrophages of WT mice, but not in TRACP+ mice. Macrophages from TRACP+ mice showed increased capacity of bacterial killing. Recombinant TRACP enzyme was capable of bacterial killing in the presence of hydrogen peroxide. These results suggest that TRACP has an important biological function in immune defense system.     

Extracellularly delivered single-stranded viral RNA causes neurodegeneration dependent on TLR7

Innate immune receptors represent an evolutionarily ancient system that allows organisms to detect and rapidly respond to pathogen- and host-derived factors. TLRs are predominantly expressed in immune cells and mediate such a response. Although this class of pattern recognition receptors is involved in CNS disorders, the knowledge of ligands leading to activation of TLRs and to subsequent CNS damage is limited. We report in this study that ssRNA causes neurodegeneration and neuroinflammation dependent on TLR7 in the CNS. TLR7 is not only expressed in microglia, the major immune cells of the brain, but also in neurons of the CNS. Extracellularly delivered ssRNA40, an oligoribonucleotide derived from HIV and an established ligand of TLR7, induces neuronal cell death dependent on TLR7 and the central adapter molecule MyD88 in vitro. Activation of caspase-3 is involved in neuronal damage mediated by TLR7. This cell-autonomous neuronal cell death induced by ssRNA40 is amplified in the presence of microglia that mount an inflammatory response to ssRNA40 through TLR7. Intrathecal administration of ssRNA40 causes widespread neurodegeneration in wild-type but not in TLR7(-/-) mice, confirming that neuronal cell death induced by ssRNA40 through TLR7 occurs in vivo. Our results point to a possible mechanism through which extracellularly delivered ssRNA contributes to CNS damage and determine an obligatory role for TLR7 in this pathway.     

Coordination sphere of the third metal site is essential to the activity and metal selectivity of alkaline phosphatases

Alkaline phosphatases (APs) are commercially applied enzymes that catalyze the hydrolysis of phosphate monoesters by a reaction involving three active site metal ions. We have previously identified H135 as the key residue for controlling activity of the psychrophilic TAB5 AP (TAP). In this article, we describe three X‐ray crystallographic structures on TAP variants H135E and H135D in complex with a variety of metal ions. The structural analysis is supported by thermodynamic and kinetic data. The AP catalysis essentially requires octahedral coordination in the M3 site, but stability is adjusted with the conformational freedom of the metal ion. Comparison with the mesophilic Escherichia coli, AP shows differences in the charge transfer network in providing the chemically optimal metal combination for catalysis. Our results provide explanation why the TAB5 and E. coli APs respond in an opposite way to mutagenesis in their active sites. They provide a lesson on chemical fine tuning and the importance of the second coordination sphere in defining metal specificity in enzymes. Understanding the framework of AP catalysis is essential in the efforts to design even more powerful tools for modern biotechnology.     

Mycotoxins in Crude Building Materials from Water-Damaged Buildings

We analyzed 79 bulk samples of moldy interior finishes from Finnish buildings with moisture problems for 17 mycotoxins, as well as for fungi that could be isolated using one medium and one set of growth conditions. We found the aflatoxin precursor, sterigmatocystin, in 24% of the samples and trichothecenes in 19% of the samples. Trichothecenes found included satratoxin G or H in five samples; diacetoxyscirpenol in five samples; and 3-acetyl-deoxynivalenol, deoxynivalenol, verrucarol, or T-2-tetraol in an additional five samples. Citrinine was found in three samples. Aspergillus versicolor was present in most sterigmatocystin-containing samples, and Stachybotrys spp. were present in the samples where satratoxins were found. In many cases, however, the presence of fungi thought to produce the mycotoxins was not correlated with the presence of the expected compounds. However, when mycotoxins were found, some toxigenic fungi usually were present, even if the species originally responsible for producing the mycotoxin was not isolated. We conclude that the identification and enumeration of fungal species present in bulk materials are important to verify the severity of mold damage but that chemical analyses are necessary if the goal is to establish the presence of mycotoxins in moldy materials.     

Unattended monitoring of potentially toxic phytoplankton species in the Baltic Sea in 1993

Variabilities in chlorophyll a fluorescence, temperature andsalinity in the surface were recorded unattended on board twomerchant ships in the Baltic Sea. When these recordings werecomplemented by automated water sampling, it was possible toanalyze the phytoplankton species composition in 426 samples.In total, 22 potentially toxic phytoplankton species or generawere detected. Nodularia spumigena was the only species thatformed extensive blooms The system has proved to be an effectiveearly warning method for exceptional and eventually harmfulalgal blooms. The possibilities for using this method as analternative, or a complement, to conventional methods in marinephytoplankton monitoring are discussed.     

Records of chrysophytes with siliceous scales (Mallomonadaceae and Paraphysomonadaceae) from Finnish inland waters

Seventy-three taxa of silica-scaled chrysophytes were found with LM and TEM in 264 samples from 141 Finnish water bodies, including the genera Mallomonas (40 taxa), Synura (9), Chrysosphaerella (3), Spiniferomonas (8) and Paraphysomonas (13). More than half of the taxa are recorded for the first time from Finland and five (Mallomonas actinoloma v. actinoloma, M. favosa, M. mangofera f. gracilis, M. scrobiculata and Spiniferomonas serrata) are new to Europe. Most taxa are illustrated with TEM micrographs and the taxonomy of some interesting species is discussed in detail. The seasonal occurrence of the commonest species is described.