Ecological succession of the microbial communities of an air-conditioning cooling coil in the tropics.

Air-conditioning systems harbor microorganisms, potentially spreading them to indoor environments. While air and surfaces in air-conditioning systems are periodically sampled as potential sources of indoor microbes, little is known about the dynamics of cooling coil-associated communities and their effect on the downstream airflow. Here, we conducted a 4-week time series sampling to characterize the succession of an air-conditioning duct and cooling coil after cleaning. Using an universal primer pair targeting hypervariable regions of the 16S/18S ribosomal RNA, we observed a community succession for the condensed water, with the most abundant airborne taxon Agaricomycetes fungi dominating the initial phase and Sphingomonas bacteria becoming the most prevalent taxa toward the end of the experiment. Duplicate air samples collected upstream and downstream of the coil suggest that the system does not act as ecological filter or source/sink for specific microbial taxa during the duration of the experiment.

Draft Genome Sequence of the Deep-Sea Bacterium Shewanella benthica Strain KT99.

We report the draft genome sequence of the obligately piezophilic Shewanella benthica strain KT99 isolated from the abyssal South Pacific Ocean. Strain KT99 is the first piezophilic isolate from the Tonga-Kermadec trench, and its genome provides many clues on high-pressure adaptation and the evolution of deep-sea piezophilic bacteria.

Complete Genome Sequence of the Deep-Sea Bacterium Psychromonas Strain CNPT3.

Members of the genus Psychromonas are commonly found in polar and deep-sea environments. Here we present the genome of Psychromonas strain CNPT3. Historically, it was the first bacterium shown to piezoregulate the composition of its membrane lipids and to have a higher growth rate at 57 megapascals (MPa) than at 0.1 MPa.

Temperature-dependent global gene expression in the Antarctic archaeon Methanococcoides burtonii.

Methanococcoides burtonii is a member of the Archaea that was isolated from Ace Lake in Antarctica and is a valuable model for studying cold adaptation. Low temperature transcriptional regulation of global gene expression, and the arrangement of transcriptional units in cold-adapted archaea has not been studied. We developed a microarray for determining which genes are expressed in operons, and which are differentially expressed at low (4°C) or high (23°C) temperature. Approximately 55% of genes were found to be arranged in operons that range in length from 2 to 23 genes, and mRNA abundance tended to increase with operon length. Analysing microarray data previously obtained by others for Halobacterium salinarum revealed a similar correlation between operon length and mRNA abundance, suggesting that operons may play a similar role more broadly in the Archaea. More than 500 genes were differentially expressed at levels up to ≈ 24-fold. A notable feature was the upregulation of genes involved in maintaining RNA in a state suitable for translation in the cold. Comparison between microarray experiments and results previously obtained using proteomics indicates that transcriptional regulation (rather than translation) is primarily responsible for controlling gene expression in M. burtonii. In addition, certain genes (e.g. involved in ribosome structure and methanogenesis) appear to be regulated post-transcriptionally. This is one of few experimental studies describing the genome-wide distribution and regulation of operons in archaea.

Life at depth: Photobacterium profundum genome sequence and expression analysis.

Deep-sea life requires adaptation to high pressure, an extreme yet common condition given that oceans cover 70% of Earth's surface and have an average depth of 3800 meters. Survival at such depths requires specific adaptation but, compared with other extreme conditions, high pressure has received little attention. Recently, Photobacterium profundum strain SS9 has been adopted as a model for piezophily. Here we report its genome sequence (6.4 megabase pairs) and transcriptome analysis. The results provide a first glimpse into the molecular basis for life in the largest portion of the biosphere, revealing high metabolic versatility.

Demonstration of Chlamydia pneumoniae in atherosclerotic arteries from various vascular regions.

Chlamydia pneumoniae (CP) has been reported to be a pathogenic agent in the mechanism leading to atherosclerosis. The majority of available data is focused mainly on coronary artery disease whereas the distribution of CP in different areas, associated with atherosclerotic disorders, has not been completely clarified. In this study we investigated the presence of CP in atheromasic plaques from five different vascular areas (basilary artery, coronary artery, thoracic aorta, abdominal aorta, renal arteries) using nested polymerase chain reaction (PCR) and immunohistochemical staining (IHC), in order to establish the putative association of CP with atherosclerotic disease. The same atheromasic plaques were also tested for the presence of Helicobacter pylori (HP) and cytomegalovirus (CMV), other putative agents of atherosclerosis, using a nested PCR technique. Our data indicate that the presence of CP can be demonstrated in 100% of patients tested, considering globally the five areas of analysis. On the other hand the presence of HP has been demonstrated in four out of 18 patients (22.2%), and CMV only in three out of 18 (16.6%). Our results strongly suggest an association between CP and atherosclerosis and highlight the need for the detection of CP in multiple vascular areas of the same patient.

Detection of Chlamydophila pneumoniae DNA in peripheral blood mononuclear cells of blood donors in the north-east of Italy.

Recent studies have implicated Chlamydia pneumoniae (now Chlamydophila pneumoniae) in the pathogenesis of atherosclerosis and demonstrated its presence within human peripheral blood mononuclear cells (PBMCs). In this study the presence of C. pneumoniae DNA was assessed, using nested PCR, in PBMCs from 169 active blood donors as a function of age, of specific antibodies and C-reactive protein. The results obtained demonstrated a high degree of global positivity (46.15%), which was higher in females (52%) than in males (43.7%). Seroepidemiological studies showed a high percentage of positivity both in subjects positive by PCR (65.91%) and negative by PCR (71.74%). The clinical implication of such finding are under study.

Photosensitizing activity of hematoporphyrin on Staphylococcus aureus cells.

The photosensitizing action of hematoporphyrin (Hp) on two Staphylococcus aureus strains was investigated to determine if the photoprocess induces in vivo damage in DNA in addition to that occurring at the level of the cytoplasmic membrane. The results obtained demonstrate that the photokilling is dependent on the Hp dose even though the two strains, having a similar Hp-binding capacity, show different levels of photosensitivity. The electrophoretic analysis of cytoplasmic membrane proteins and DNA (chromosomal and plasmidial) suggests that the membrane represents the primary target of the photoprocess, while the DNA, that is damaged both in vivo and in vitro only at relatively long irradiation time, might be a secondary target. Moreover, the photoprocess results in mutagenesis for Salmonella typhimurium tester strains. This information is particularly important in view of the potential use of photodynamic therapy for the treatment of microbial infections.

Zearanol metabolism by subcellular fractions from lamb liver.

Zeranol (7-alpha-zearalanol or alpha-ZAL) metabolism in vitro by subcellular fractions (microsome and cytosol) from lamb livers was investigated. The use of a high performance liquid chromatography (HPLC) technique capable of resolving epimers, revealed that when nicotinamide adenine dinucleotide (NAD) was added as a co-factor to metabolic mixtures, the oxidized form, zearalanone (ZAN) was the major metabolite, although a small amount of 7-beta-zearalanol (beta-ZAL) was also produced. In order to confirm beta-ZAL as a product of ZAN reduction, the metabolism of the latter, by microsome and cytosol in the presence of NADH as co-factor, was investigated. The results obtained revealed that both alpha-ZAL and beta-ZAL were present at the end of the incubation, the former at a higher concentration than the latter. When NAD and NADH were added as cofactors to incubation mixtures containing alpha-ZAL, the production of beta-ZAL was increased as a consequence of the higher ZAN reduction in the presence of the reducing co-factor. Nevertheless, ZAN remained the major metabolite produced from alpha-ZAL by both the subcellular fractions investigated.

Effect of PCB on some MFO enzyme activities in pregnant and virgin rabbits.

Fenclor 64 (a PCB's commercial mixture) was administered twice i.p. to virgin and pregnant New Zealand rabbits at the dose of 100 mg/Kg to evaluate its inducing properties on the following hepatic microsomal MFO activities: p-nitro-anisole-O-demethylase, amino-pyrine-N-demethylase, acetanilide-hydroxylase and aryl-hydrocarbons-hydroxylase. The results indicate that Fenclor 64 evoked a "mixed type" induction in virgin as well as in pregnant rabbits since it increased liver weight, cytochrome P-450 levels, as well as p-nitro-anisole-O-demethylase and acetanilide-hydroxylase. Pregnancy by itself affects only amino-pyrine-N-demethylase levels.

The metabolism of zearalenone in subcellular fractions from rabbit and hen hepatocytes and its estrogenic activity in rabbits.

The in vitro reduction of zearalenone (ZEN) by subcellular fractions from hen and rabbit hepatocytes clearly shows species-specific differences in the cofactor requirements, rate of metabolism and production of metabolites. The presence of NADH as cofactor in the reaction mixtures enhanced only the reducing activity of the microsomal fraction from rabbit hepatocytes, while NADPH enhanced the reducing activities of the cytosolic fraction from rabbit and both the microsomal and cytosolic fractions from hen hepatocytes. Furthermore, we observed that hen hepatocytes metabolize faster and produce beta-zearalenol (ZEL) as the major metabolite, whereas rabbit hepatocytes metabolize ZEN slowly and mainly into alpha-ZEL, the more uterotrophic metabolite. These last findings are closely related to the higher sensitivity to ZEN estrogenic effects observed in rabbits during the toxicity test involving p.o. administration of the mycotoxin to the animals at 3 dosage levels (0.1, 1, 2 mg/kg body wt).