[3] may be sufficient in couples in whom

it is known to both partners that the HIV-infected individual has high compliance. Because of differences in demography and health care management, our results presumably cannot be applied to developing countries. Assuming that there is a viral threshold of infectiousness, our results indicate that the risk of viraemia is very low in patients on successful antiretroviral treatment. HIV-infected patients have, however, an increased risk of abrupt viraemia in not only the first 6 months but the first 12 months of episodes with undetectable VL. We thank the staff of our clinical departments for their continuous support and enthusiasm. Centres in the Danish HIV Cohort Study: Departments of Infectious Diseases at Copenhagen University Hospitals, Rigshospitalet (J. PD-332991 Gerstoft and N. Obel) and Hvidovre (G. Kronborg), Odense University Hospital (C. Pedersen), Androgen Receptor Antagonist ic50 Aarhus University Hospitals, Skejby (C. S. Larsen) and Aalborg (G. Pedersen), Herning Hospital (A. L. Laursen), Helsingør Hospital (L. Nielsen) and Kolding Hospital (J. Jensen). Conflicts of interest NO has received research funding from Roche, Bristol-Myers Squibb, Merck Sharp & Dohme, GlaxoSmithKline, Abbott, Boehringer Ingelheim, Janssen-Cilag

and Swedish Orphan. FNE has received research funding from Merck Sharp & Dohme. JG has received research funding from Abbott, Roche, Bristol-Myers Squibb, Merck Sharp & Dohme, Pharmasia, GlaxoSmithKline, Swedish Orphan and Boehringer Ingelheim. LHO, MVL, LDR and TQ have no conflicts of interest. Financial support The study was

financed by The Research Foundation at Copenhagen University Hospital, Rigshospitalet and Faculty of Health Science, Copenhagen University. The fund providers had no role in the study design; in the collection, management, analysis or interpretation of data; in the preparation, review or approval of the manuscript; or in the decision to submit the article for publication. The researchers are independent of the fund providers. Financial disclosure The authors have no conflict of interest to report. “
“The PubMed database was searched under the following heading: HIV or AIDS and central nervous system infection or space-occupying lesion or meningitis 3-mercaptopyruvate sulfurtransferase or encephalitis or pneumonitis and/or Cryptococcus neoformans, cryptococcosis, Toxoplasma gondii, toxoplasmosis, progressive multifocal leukoencephalopathy, cytomegalovirus or CMV. Disease of the central nervous system (CNS) is common in HIV. It may be a direct consequence of HIV infection or an indirect result of CD4 cell depletion. Presentation may be predominantly manifested as a space-occupying lesion(s), encephalitis, meningitis, myelitis, spinal root disease or neuropathy (Table 2.1), and may occur in isolation or together with other HIV-related disease.

The majority of axonal mitochondria were stationary for 3 h at both developmental stages, with a small number of appearance (red arrowheads) and disappearance (white arrowheads) events. The mitochondrial population identified at t = 0 min Selleck AZD5363 progressively changed their positions with time. The fraction of mitochondria that remained at their initial positions was calculated as a position survival rate

P(t) (see ‘Materials and methods’). To examine the relationship between the proximity to presynaptic sites and mitochondrial dynamics, P(t) was measured from mitochondria near presynaptic sites (synaptic) and also away from presynaptic sites (non-synaptic; Fig. 3D and E). Because mitochondria found at t = 0 min included both stationary and mobile mitochondria, Δ(P(0) − P(180)) was not

an appropriate estimate of mitochondria that started to move during the 180 min observation period. Dactolisib concentration Instead, we used Δ(P(30) − P(180)) as an index of the transition from stationary to mobile state (Fig. 3G and H). Using this index, we found that synaptic mitochondria were less likely to restart translocation than non-synaptic mitochondria at both developmental stages (2 weeks, t14 = 4.32, P < 0.001; 3 weeks, t12 = 3.57, P = 0.004; unpaired t-test; Fig. 3H). Both synaptic and non-synaptic mitochondria were less likely to transit to mobile state at 3 weeks than at 2 weeks (all, t13 = 9.65, P < 0.001; synaptic, t13 = 8.05, P < 0.001; non-synaptic, t13 = 4.89, P < 0.001; unpaired t-test; Fig. 3H). The treatment of neurons at 20 DIV with the sodium channel blocker TTX increased the transition probability to mobile state (3 weeks + TTX, 3297 mitochondria from n = 7 experiments; MycoClean Mycoplasma Removal Kit all, t12 = 4.72, P < 0.001; unpaired t-test; Fig. 3C,E,F and H). This effect was present in both synaptic and non-synaptic mitochondria (synaptic, t12 = 3.95, P = 0.002; non-synaptic, t12 = 3.88, P = 0.002; unpaired t-test; Fig. 3H). These results suggest that neuronal maturation, proximity

to synaptic sites and neuronal activity affect the stability of stationary mitochondria in the axon. We estimated the fraction of mobile mitochondria at t = 0 min [mobile fraction; calculated from P(t) at t = 0, 30 and 60 min; see Eqn (3) in 'Materials and methods'] (Fig. 3G). The mobile fraction at 3 weeks was smaller than at 2 weeks (t13 = 4.98, P < 0.001; unpaired t-test; Fig. 3I) and at 3 weeks with TTX (t12 = 3.82, P = 0.002; unpaired t-test; Fig. 3I). These results suggest that the ratio of mobile to stationary mitochondria in the axon was dependent on neuronal maturation and activity. In time-lapse imaging over 3 h, the majority of axonal mitochondria imaged at the initial time point remained stationary throughout the experiments (Fig. 3D–F), suggesting that the duration of stationary state is usually longer than several hours.

1, SAS Inc., Cary, NC, USA) except MCA which was conducted with XLStat 2007.5 software (Addinsoft, Paris, France). Between June 2005 and May 2009, travel outside Canada was recorded in 493 cases reported in the study area. Six of these cases reported onset dates before their departure dates, three cases reported onset dates after departure and before the minimum incubation period, and 38 cases reported onset dates after their return

dates and Trichostatin A datasheet beyond the maximum incubation period. Thus, these 47 cases were considered as DC, leaving 446 TRC for analysis. The three most frequent diseases among TRC were Campylobacter enteritis, non-typhoidal salmonellosis, and giardiasis, accounting for three quarters of the cases (Table 1). Thirty-four cases were hospitalized; the most with salmonellosis (12 cases) or paratyphoid or typhoid fever (9 cases) (Table 1). Overall, the RO4929097 chemical structure most common symptoms were diarrhea (77%), abdominal pain (58%), malaise (52%), fever (51%), nausea (44%), and headache (36%) with some variations between illnesses (Table 1). The onset date was available for 379 cases (85%)

with the following yearly distribution (from June to May the following year): 82 cases in 2005 to 2006, 117 cases in 2006 to 2007, 97 cases in 2007 to 2008, and 83 cases in 2008 to 2009. The total monthly distribution combined over 4 years ranged from 23 cases in October to 51 cases in August. No significant differences were found between years and months. Both onset and return dates were recorded in 353 cases (79%). The onset date for 204 of these cases (58%) occurred after their return date; and within the first 4 days for 75% of them (Figure 1). The other cases (148/353 or 42%) became ill while abroad, within the last 7 days prior to return for 60% of them (Figure 1). Among the cases who became ill abroad with known departure date (n = 143), the delay between

departure and onset dates had the following quartiles: 5 (Q1), 7 (median), and 20 days (Q3). Overall, 50.4% TRC were Aspartate male with some variations between diseases (Table 2). Age ranged from a few months to 80 years with a right skewed distribution, the quartiles being 12 (Q1), 26 (median), and 46 (Q3). The disease-specific age distribution showed potentially different patterns; cryptosporidiosis TRC were less than 40 years old, cyclosporiasis TRC over 25 years, and hepatitis A TRC under 25 years (Table 2). Among the 446 TRC, 42 (9.4%) were classified as new immigrants as a result of adoption (6 cases), refugee status (16 cases), or immigration (20 cases). Most of them were in the 5 to 14 years (23 cases) or <5-year-age groups (8 cases). Overall, the main destinations were to Latin America/Caribbean (160 cases) and Asia (134 cases), with some variations between the diseases (Table 3). Destination for cases identified as new immigrants were Asia (23 cases), Africa (12 cases), and Latin America/Caribbean (7 cases).

Y.S. from the Kearney Crizotinib in vivo Foundation of Soil Science and the faculties of UCR and UofA. The authors gratefully acknowledge M.G. Klotz, B.D. Lanoil, and anonymous reviewers for critical comments on this and previous versions of the manuscript. Fig. S1. Growth curves of AOB cultivated in HEPES- (a) and phosphate- (b) buffered medium; Nitrosomonas

europaea (squares), Nitrosomonas eutropha (circles), and Nitrosospira multiformis (triangles). Table S1. Genes and PCR primers used in this study. Please note: Wiley-Blackwell is not responsible for the content or functionality of any supporting materials supplied by the authors. Any queries (other than missing material) should be directed to the corresponding author for the article. “
“Three indigenous isolates of Bacillus sphaericus (ISPC-5, ISPC-6 and ISPC-8), along with standard 2362 and 1593 strains, were evaluated for spore viability check details and mosquitocidal activity. Among these, ISPC-8 was the most viable and virulent isolate, exhibiting a significantly higher total viability count (TVC) and lower

LC50 values. The TVC of the standard strains ranged from 4.0 to 9.2 × 108 spores mL−1, whereas it was 1.3 × 109 spores mL−1 for ISPC-8. The LC50 values of ISPC-8, 2362 and 1593 against Culex quinquefasciatus were 0.68 × 103, 1.22 × 103 and 1.85 × 103 spores mL−1, respectively. The ISPC-8 was further assessed for host spectrum and found to be more active against C. quinquefasciatus, followed by Culex tritaeniorhynchus, Aedes albopictus and Aedes aegypti. The ISPC-8 strain was thus found to be a promising isolate for developing biopesticides. Among the indigenous strains, only ISPC-8 was found to have binary toxin genes (binA and binB). Comparative sequence analysis revealed that the BinA (41.9 kDa) protein of ISPC-8 differs by one amino acid (R197M), whereas BinB (51.4 kDa) differs by two amino acids (H99P, P174S) as compared with 1593 and 2362 strains. The purified binary proteins of ISPC-8 showed an LC50 value of 6.32 ng mL−1 against C. quinquefasciatus larvae

after 48 h. The adverse environmental effects associated with chemical insecticides have led to the search for alternative methods for controlling different disease-transmitting mosquito species. The ZD1839 chemical structure use of entomopathogenic microorganisms appears to be one of the promising alternatives, and microorganisms such as Bacillus sphaericus and Bacillus thuringiensis ssp. israelensis have been quite effective against different mosquito species (Federici et al., 2007). These two bacteria differ in the nature of their toxins and host range. In general, B. sphaericus is more active against Culex and Anopheles sp., whereas B. thuringiensis ssp. israelensis is more active against Aedes and Culex sp. (Charles et al., 1996). Bacillus sphaericus has an additional attribute as it persists in polluted aquatic environments, whereas in this environment, the toxicity of B. thuringiensis ssp. israelensis is lost rapidly (Silapanuntakul et al.

, 1978; Cernakova et al., 1991; Piutti et al., 2003). selleckchem Heterogeneous distribution of herbicides in field crops may lead to local maxima of herbicide concentration that exceed reported mean values (Marsh et al., 1978) but current and previous data suggest that the impact of MCPA and Bentazon on oxygen-dependent cellulose and cellobiose degradation is minimal under environmental concentrations. 16S rRNA gene transcript numbers of total soil Bacteria and five family-level taxa of Bacteria that have previously been identified as active members of the cellulolytic and saccharolytic community of the same soil (Schellenberger et al., 2010) were determined in soil samples of cellulose-supplemented

microcosms using reverse transcriptase quantitative PCR (RTqPCR). In the oxic, cellulose-supplemented microcosms, fungal hyphae grow on the cellulose sheets, whereas in anoxic treatments,

fungal hyphae were not observed (data not shown). Thus, it is very likely that fungi contributed to aerobic cellulose degradation. The metabolic response to Bentazon and MCPA of well known and novel, i.e. as yet uncultivated, taxa that have all been proven to contribute to cellulose and cellobiose degradation in the investigated soil (Schellenberger et al., 2010) was evaluated to reveal the taxa that may cause the reduced degradation rates under anoxic conditions. The specificity of the utilized RT qPCR assays has been demonstrated previously in the same soil (Schellenberger et al., 2011). In the presence of 2.4 μmol gsoil selleck inhibitor DW−1, Bentazon and MCPA, transcript numbers of total soil Bacteria and all analysed family-level taxa were lower in both oxic and anoxic microcosms at the end of the experiment

compared with herbicide-free microcosms (Fig. 3; Table 2). Reports about a reduction Oxalosuccinic acid of microbial growth in pure culture by both herbicides support these findings (Cernakova et al., 1991; Ahtiainen et al., 2003; Cabral et al., 2003; Galhano et al., 2009). Transcript numbers of Planctomycetaceae and uncultured ‘Sphingo’ (Bacteroidetes) were significantly lower under oxic conditions, whereas those of uncultured ‘Cellu’ (Bacteroidetes) and Clostridia of group I (Clostridiaceae; according to Collins et al., 1994) were significantly lower under anoxic conditions (Table 2). Most known anaerobic cellulolytic bacteria that have been isolated belong to Clostridia group III (Collins et al., 1994). Clostridiaceae assimilated carbon from supplemented 13C-enriched cellulose and were metabolically stimulated under anoxic conditions in the same soil (Schellenberger et al., 2010, 2011). Development of primers that exclusively target these organisms failed. Thus, it cannot be excluded that the metabolism of not only Clostridia of group I but also group III was inhibited by herbicides.

, 1999). They are widespread throughout the photic regions of the world’s oceans between 40°S and 50°N, with cell densities of up to 105 cells mL−1 in the central oligotrophic gyres (Partensky et al., 1999). They are principally distinguished

into two taxonomic Ion Channel Ligand Library screening clades due to physiological niche adaptation to light intensity: high light- and low light-adapted ecotypes (Moore et al., 1998; West & Scanlan, 1999; Rocap et al., 2003). A great deal of interest has arisen around Prochlorococcus due to its small size and specifically its near-minimal genome. Indeed, the chromosomes of most Prochlorococcus strains demonstrate significant genomic reduction, revealing a central conserved core set of essential genes and a variable shell, which is hypothesized to reflect each individual strain’s evolutionary adaptation to a specific environmental niche (Kettler et al., 2007; Shi & Falkowski, 2008). Closer inspection of Prochlorococcus genomes reveals that selleck chemicals llc the majority of these strain-specific genes (74% in the case of Prochlorococcus strain MED4) are located in highly variable ‘genomic islands’, suggesting a mosaic structure that continually undergoes genomic rearrangement (Coleman et al., 2006). A suggested source of pressure for these organisms to reduce genome as well as cell size is thought to be reduced nutrient

availability (Raven, 1998), which is a characteristic of subtropical oceans,

particularly phosphate (P). Indeed, P concentrations are hypothesized to have affected domain shifts from a eukaryotic to a prokaryotic life in these oligotrophic regions (Karl et al., 1995, 2001). Also, recent studies have found that phytoplanktonic species within nutrient-poor oceanic biomes substitute phospholipids with sulpholipids in order to conserve Oxymatrine ambient phosphorous for more essential metabolic use in the face of competition from heterotrophic bacteria (Van Mooy et al., 2006, 2009). A recent study of MED4 showed that a unique suite of genes was upregulated under P stress (Martiny et al., 2006). Most of these genes are orthologues of Escherichia coli genes located in and around the phoB operon, but another set are located within a variable genomic island, ‘Island 5’, and unique to MED4. The function of these genes is as yet uncharacterized; however, some putative annotations are available at GenBank (http://www.ncbi.nlm.nih.gov/). It is clear that the availability and ambient concentration of inorganic P within oligotrophic regions is a crucial factor determining the success of MED4 within those environments. Therefore, this study seeks to ascertain the global quantitative proteomic response of MED4 to longer term P starvation, and thereby providing further insight into how this organism responds to P stress.

, 2001) to identify the closest relatives. GenBank accession numbers were assigned

for the 16S rRNA gene sequences of the isolates (GU086416, GU086419, GU086421, GU086430, GU086437, GU086451) and of the DGGE bands (FJ972838–FJ972861). Multiple alignments and distance matrix analyses were conducted using the mega 3.0 software package. A phylogenetic tree was constructed using the neighbour-joining method and bootstrap analysis based on 1000 replicates. DGGE analysis of the 16S rRNA gene fragments was used to examine the effects of dichlorvos application upon the bacterial community of the phyllosphere at the molecular level. As CH5424802 nmr shown in Fig. 1, the DGGE profiles of the samples after dichlorvos treatment were different from those of the control samples, with the appearance of new bands (bands A1, A3, A4, A5, A6, A8, A9, A13 and A14) and the loss of others (bands A11, A12 and BTK inhibitor A19). Band A10 was detected in all samples. On day 0, the patterns of bands from the control and treated samples were similar. After treatment with dichlorvos for

1 day, the bands of the treated sample increased rapidly relative to those of the control. After a few days, the new bands decreased and the profiles of the control and treated samples became similar again. Band A12, which had appeared on days 2 and 4 and then disappeared, may indicate that the microorganisms were susceptible to the auxiliary solvent that was added to the pesticide. Band A7 appeared after the application of dichlorvos with the associated auxiliary solvent and persisted. The effect of dichlorvos treatment on the phyllosphere bacterial community was further confirmed by dendrogram analysis (Fig. 2), which demonstrated two distinct clusters formed by the dichlorvos-treated and control samples (similarity coefficients were <53%),

except on the second day. Significant changes (P<0.01) were observed in the bacterial community composition after the dichlorvos treatment. Temporal changes in the composition of the bacterial community Etoposide molecular weight were also detected by grouping the profiles according to the sampling dates within clusters I and II (Fig. 2). In cluster I, the samples were separated into two smaller clusters according to the sampling date: treatment days 0, 4, 6 and 7 and control day 2 clustered together but separately from treatment day 1. In cluster II, the bacterial community also showed variation. The control samples on day 0 and 6 had similar profiles (similarity coefficient >90%) and clustered together with the day 2 treated sample, but separately from the other control samples. The difference between the control and treated samples from day 2 and the other samples is probably because some bacterial species were sensitive to the solvents added to the pesticide. The results of the sequence similarity searches for the 24 bands labelled in Fig. 1 are shown in Table 1.

The different frequencies of HLA-B*5701 found in patients from different African countries strongly suggest greater utility of HLA-B*5701 screening in some African groups compared with others. Although ethnic-based

pharmacogenetic screening in UK clinics with diverse populations is unlikely to be practical and also likely to be ethically unacceptable, our figures add to the need for caution when considering screening in diverse African settings. Despite an overall sample size of 1502, only two sub-divisions had a sufficiently large sample to allow meaningful interpretation of the prevalence rate [White/Eurasian and Niger-Congo with prevalence rates of 7.95% (CI 5.88%–10.02%) and 0.52% (CI 0.18%–1.52%), respectively]. On the basis of previous Fluorouracil clinical trial work, we sub-divided our African patients according to linguistic index that language groups might reflect genetic structure [9]. However, more recent data suggest that this

may not necessarily be true in all settings and particularly not African ones [14]. In contrast, a recent, well-publicized study of 121 African populations demonstrated genetic clustering across the Niger-Congo JQ1 (Niger-Kordofanian) linguistic populations [15]. Our data, where both Ugandan and Zimbabwean populations were classified as Niger-Congo (Bantu) but had very different HLA-B*5701 prevalences, demonstrate the difficulties in using such classifications to distinguish populations Dipeptidyl peptidase in genetic studies of specific, non-neutral alleles. Our study was not able to distinguish northern (Nilotic) Ugandans from Bantu Ugandans, so it is possible that the different rates among

Zimbabweans and Ugandans were because of cross-classification. However, a significant majority of Ugandans in the United Kingdom are thought to be Bantu and HLA-B*5701 frequency among Nilotics has been reported to be lower than among Bantu [4]. The 244 unclassifiable subjects underline the difficulties in basing decisions on these self-reported measures of ethnicity. Only one of the three HLA-B*5701 positive subjects in the Niger-Congo sub-division self-reported as genetically homogenous reflecting the potential of genetic admixture to complicate analysis. Future studies may consider the use of ancestry information bio-markers to define population groups more accurately. The single false-positive result in a local laboratory reinforces the need for robust laboratory quality assurance. It is reassuring that Sequence specific primer (SSP) methodology failed safe by identifying the patient as HLA-B*5701 positive; by doing so it ensured patient safety was maintained. In the present study, HLA-B*5701 prevalence in the UK was similar to previously reported rates in White HIV-infected subjects but considerably lower than those reported in Black HIV-infected subjects, probably as a result of the large proportion of Black subjects that were of African origin. In addition, 99.

brasilense (Thirunavukkarasu et al., 2008; Mishra Omipalisib cell line et al., 2011). Chemotaxis is the ability bacteria have to sense gradients of compounds and to drive motility toward the most appropriate niche and is an important trait for survival in the rhizosphere and in plant–microbe interactions (Alexandre, 2010). Signal transduction systems enable cells to detect and

adapt to these changes by executing appropriate cellular responses, such as regulation of gene expression or modulation of the swimming pattern. The best characterized signal transduction system is the one regulating the run or tumble swimming bias via chemotaxis in Escherichia coli (Wadhams & Armitage, 2004). This signal transduction system consists of a set of conserved proteins, which includes CheA, CheW, CheY, CheB, and CheR and a set of chemoreceptors known as methyl-accepting proteins that perceive environmental cues. In A. brasilense, energy taxis is dominant (Fig. 1), Ibrutinib with responses to most stimuli in this bacterium being triggered

by changes in the electron transport system (Alexandre et al., 2000). Greer-Phillips et al. (2004) identified a novel chemoreceptor-like protein, named Tlp1, which serves as an energy taxis transducer. A tlp1 mutant was shown to be deficient in chemotaxis toward several rapidly oxidizable substrates, to taxis to the terminal electron acceptors oxygen and nitrate, and to redox taxis, suggesting that Tlp1 controls energy taxis in A. brasilense. The tlp1 mutant is also impaired in colonization of plant roots (Greer-Phillips et al., 2004). Stephens et al. (2006) characterized the CheB and CheR components of the chemotaxis-like signal transduction pathway Che1 in A. brasilense. Characterization of cheB, cheR, and cheBR null mutants showed that these genes significantly influence chemotaxis and aerotaxis but are not essential for these behaviors, suggesting that multiple chemotaxis systems

are present and contribute to chemotaxis and aerotaxis in A. brasilense. A further study characterized mutants for genes cheA1 and cheY1, also components of the Che1 system. As for the cheB/cheR mutants, these mutants were defective but not null for chemotaxis and aerotaxis, and showed a minor defect in swimming pattern. Detailed characterizations of these second mutants lead the authors to propose that the Che1 chemotaxis-like pathway modulates cell length as well as flocculation (Bible et al., 2008). Recently, Carreño-López et al. (2009) identified gene chsA as an important component of the chemotaxis signaling pathway in A. brasilense. The encoded protein, ChsA, displays characteristic signaling protein architecture, containing a PAS sensory domain and an EAL domain. The authors showed that a chsA null mutant was impaired in surface motility and chemotactic response, although it was not affected in synthesis of polar and lateral flagella, thus strengthening a key role of this gene in chemotaxis.

casei). This suggests that yahD and yaiA encode proteins of the same or related biological pathways. In E. faecalis and S. aureus, these operons also encode a predicted regulator. The yaiB gene, on the other hand, is in the same operon only in L. lactis and L. casei, while it is present as an adjacent, divertantly transcribed gene in E. faecalis and B. subtilis. Based on sequence similarity, the yaiA-like genes shown in Fig. 1 have

been annotated as putative glyoxylases. However, a direct demonstration of the function of any of these genes is not available. YahD exhibits 31%, 32%, 34%, 32% and 42% sequence identity with the most homologous proteins aligned in Fig. 2. In all these proteins, there is a conserved catalytic Ivacaftor purchase triad typical of α/β serine hydrolases, characterized by Ser107, Asp157 and His188 of L. lactis YahD. The closest relative of this group of aligned proteins that has been characterized biochemically is EstB of Pseudomonas fluorescence. It shares 17% sequence identity with YahD of L. lactis and functions as a carboxylesterase with maximal hydrolytic activity towards (p-nitro)phenyl acetate (Hong et al., 1991). Because α/β serine hydrolases are an extremely diverse family of enzymes, this does not imply a function for related enzymes. To learn more about the function of YahD of

L. lactis in copper homeostasis and stress http://www.selleckchem.com/products/BIBF1120.html response, we analyzed in vivo expression by Western blot analysis with an antibody against YahD. Expression was upregulated by copper, with maximal expression observed at 200 μM extracellular Cu2+ (Fig. 3). Among other metals tested, 20 μM Cd2+ induced YahD expression to even higher levels than copper, while Ag+ at the same concentration induced YahD only marginally. Zn2+, Fe2+, Ni2+ and Co2+

failed to stimulate YahD expression. Likewise, oxidative stress by 4-nitroquinoline-1-oxide or hydrogen peroxide and nitrosative stress by nitrosoglutathione Protein tyrosine phosphatase failed to induce YahD. This induction specificity is typical for genes under the control of the CopR copper-inducible repressor and suggests that CopR is the sole regulator governing the expression of YahD. In line with this, Hg2+ and Pb2+ also failed to induce YahD (not shown). To functionally and structurally characterize YahD, the gene was cloned in an expression vector as a fusion protein with a chitin affinity tag, connected to the N-terminus of YahD via a self-cleaving intein. Self-cleavage of the intein with dithiothreitol resulted in YahD with Ala-Gly-His added to the N-terminal methionine. Preparations with >99% purity and of the expected apparent molecular weight of 23.6 kDa were routinely obtained with a yield of 2 mg L−1 of culture (Fig. 4). Purified YahD was highly soluble and stable when stored frozen at −80 °C. Sequencing of the cloned yahD gene revealed two amino acid replacements, M191T and N199K, relative to the L.