, 2007), it is reasonable to postulate that exogenous glutathione affects the defenses against the oxidative stress caused by antibiotics.

In particular, our work shows that glutathione was able to modify the susceptibility of S. aureus to ciprofloxacin and gentamicin depending on the quantity of oxidative stress generated, which was higher in the resistant strain than in the sensitive one. These results could prove useful in future treatments combined with antibiotics. This work was supported by grants from BID 1728 PICTO 36163 and SECyT-UNC. We thank native English speaker Dr Paul Hobson (Asoc. Argentina de Cultura Británica) for revision of this manuscript. P.L.P. is a PhD fellow from the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and M.C.B. GDC-0068 ic50 is a member of the Research Career of CONICET. “
“To characterize

the potential epidemiological relationship between the origin of Rhodococcus equi strains and the type of their virulence plasmids, we performed a comparative analysis of virulence plasmid types encountered in 96 R. equi strains isolated from (1) autopsied horses, (2) organic samples (horse faeces, manure and straw) and (3) environmental selleck screening library samples. Our results revealed no clear epidemiological link between virulence plasmid type and the origin of R. equi strains isolated from horse-related environments. To understand this result, we determined the nucleotide sequence of the second Pregnenolone most frequently isolated virulence plasmid type: a 87-kb type I (pVAPA116) plasmid and compared it with the previously sequenced (and

most commonly encountered) 85-kb type I (pVAPA1037) plasmid. Our results show that the divergence between these two plasmids is mainly due to the presence of three allelic exchange loci, resulting in the deletion of two genes and the insertion of three genes in pVAPA116 compared with pVAPA1037. In conclusion, it appears that the divergence between the two sequenced rhodococcal virulence plasmids is not associated with the vap pathogenicity island and may result from an evolutionary process driven by a mobility-related invertase/resolvase invA-like gene. Rhodococcus equi is a major horse pathogen that generally affects foals of up to 6 months old, and is considered to be one of the most significant pathogens in the equine breeding industry (von Bargen & Haas, 2009). This Gram-positive, facultative intracellular coccobacillus, a member of the mycolic acid-containing group of actinobacteria, is the causative agent of suppurative bronchopneumonia associated with a high mortality rate in horses, often accompanied by ulcerative enteritis and mesenteric lymphadenitis and, more rarely, by septic physitis and osteomyelitis (von Bargen & Haas, 2009). Rhodococcus equi is also an opportunistic zoonotic pathogen that causes cavitary pneumonia predominantly in immunocompromised humans, particularly in AIDS patients and organ transplant recipients (Hondalus, 1997).

Supplementary searches to find additional published and unpublished studies were conducted in the Food and Drug Administration Pifithrin-�� mw registry (accessed 11 October 2009) and the Clinical Trials registry (clinicaltrials.gov; accessed 11 October 2009). References of the articles included in our systematic review were also manually reviewed. Two reviewers independently reviewed all titles and abstracts for eligibility in an unblinded and standardized manner; all disagreements were resolved by a third reviewer. A data

extraction form was created, pilot-tested on four eligible studies, and then refined accordingly. Data collected were study design, trial participant characteristics, inclusion/exclusion criteria, study intervention including dosages and duration of follow-up, and primary/secondary outcome measurements. Data from all of the included studies this website were then abstracted and summarized independently by two reviewers using the data extraction form. Discrepancies were resolved by repeated review and discussion between reviewers. Data in the clinical trials registry were compared with those of the published journal article when possible. We assessed the methodological quality of all articles included in our systematic review using the Risk of Bias Tool

recommended by the Cochrane Handbook for Systematic Reviews of Interventions [12]. The data gathered from the risk of bias assessment are presented in our systematic review to identify studies that were compromised in terms of methodological quality, but these data were not utilized in our calculations of summary effect. Each study was graded as having a low risk, high risk, or unclear risk of bias in accordance with the Cochrane Collaboration Tool. The summary of the differences in treatment effects between GH axis treatments and placebo is given in terms of weighted mean differences (WMDs). No qualitative measures are

included in the treatment effects reported. For nine of our ten included articles, no calculations or estimates were needed to replace data missing from the published reports. We were unable to reach Waters et al. to request additional unpublished data, and thus we estimated values of LBM based on graphs provided in their study. We used a standardized formula to calculate the standard deviations from PDK4 confidence intervals [12]. Summary treatment effects were calculated with the Cochrane Collaboration Review Manager Version 5 (revman 5) using the random effects model. This model provides a conservative estimation and takes into account variance between studies in terms of quality and sample size. A test of heterogeneity was applied to the included studies to evaluate the magnitude of differences between the studies for the overall treatment effect of GH axis drugs vs. placebo, as well as for subgroup analyses for each GH axis drug vs. placebo.

, 1995; Honda et al., 1998) on cell growth and desulfurizing

activity. In a study on desulfurization by R. erythropolis IGTS8 in an acetate-based medium, Honda et al. (1998) observed that sulfate promoted higher cell growth than DBT. To study this phenotype, we performed flux balances for two scenarios (Table 2) with unlimited acetate uptake. In run 1, we fixed the DBT (sulfate) uptake at 20 (0.0) mg g−1 dcw h−1. In run 2, we fixed sulfate (DBT) at 20 (0.0) mg g−1 dcw h−1. Our model gave a higher cell growth rate (1.29 vs. 0.84 h−1) for sulfate (run 2) than DBT (run 1). Then, we fixed the acetate uptake at 20 mg g−1 dcw h−1 Saracatinib order and studied two more scenarios (Table 2). In run 3, we allowed unlimited (zero) sulfate (DBT) uptake, and did the reverse in run 4. Again, we obtained a higher growth (1.4 vs. 1.06 h−1) for sulfate (run 3) than DBT (run 4). After studying sulfate and DBT separately, we also studied them together (run 5 in Table 2) for a fixed acetate uptake of 20 mg g−1 dcw h−1. We fixed the sulfate uptake at 2.16 mg g−1 dcw h−1 and allowed unlimited DBT. This sulfate

uptake is 10% of its maximum (21.6 mg g−1 dcw h−1) observed in run 4. The model showed a higher growth rate of 1.12 h−1 compared with 1.06 h−1 obtained previously for run 3 (unlimited DBT, zero sulfate). The DBT uptake was also lower (22.08 vs. 25.76 mg g−1 dcw h−1). This suggests that the BVD-523 concentration organism may grow faster when it fulfills a part of its sulfur needs via sulfate rather than DBT. In other words, the organism may prefer sulfate when both DBT and sulfate are present. Because sulfate yields a higher growth rate than DBT, the organism may use DBT only if sulfate is not present. This clearly confirms the results of Honda et al. (1998). Honda et al. (1998) reasoned that the observed lower cell growth with DBT was due to the toxic effect of HBP (its desulfurized product). Because our model does not include such toxic effects, we cannot deny this

as a probable explanation. However, we have the following alternate explanation from our study. Rhodococcus erythropolis needs sulfate and sulfide to synthesize its sulfur-containing biomass precursors. If fantofarone it uses DBT as the sulfur source, then it must use the 4S pathway. 4S converts DBT to sulfite, which is converted to sulfate and sulfide by the sulfur metabolism and then incorporated into the biomass precursors. However, the organism needs 4 mol NADH mol−1 DBT to use DBT in the above manner. In contrast, the organism does not need this extra NADH for metabolizing sulfate. Thus, the organism prefers the energetically less expensive sulfate over DBT for its growth. Although our reduced model does not include all the reactions involving NADH, it is known that NADH is an essential component for growth. When the organism is forced to use DBT, NADH available for other growth-critical activities inside the cell reduces, and thus cell growth reduces.

The program se-al 2.0a11 carbon (Rambaut, 1996) was used for alignment of the ITS sequences of the sea turtle infecting fungal isolates and selected sequences obtained from the NCBI nucleotide databases (Table 2). For the external group, a sequence of Fusarium staphyleae (AF178423) was selected based on a previous phylogenetic study of the genus Fusarium (O’Donnell, 2000). The programs paup 4.0b10 (Swofford, 2003) and mr. bayes

3.1 (Ronquist & Huelsenbeck, 2003) were used for phylogenetic analyses. In the analysis with paup, we applied maximum parsimony analysis following the heuristic search Metformin solubility dmso and bootstrap support (BS) as a method of support (Felsenstein, 1985). The fast Stepwise addition with 10 000 replicates was used. For the Bayesian analysis, the GTR+I+G (for 2 000 000 generations and 12 simultaneous chains) evolution model was followed. The first 1000 trees obtained were discarded and a consensus tree was obtained with the last 19 000 trees. Freshly oviposited eggs of C. caretta showing no signs of infection were collected directly from cloacae of four nesting females (six

eggs per female) to prevent fungal contamination from contact with the sand. The eggs were collected on Boavista Island in a location close to where infected nests had previously been observed. Eggs were maintained in plastic containers (c. 500 mL) with sterile vermiculite as an incubating substrate and were incubated in two artificial incubators (FB 80-R-Reptiles, Jaeger Bruttechnik) at 29.5±0.5 °C. This is the pivotal temperature for

loggerhead Selleck Napabucasin egg development (Wibbels, 2003) and adequate for artificial incubation (Booth, 2004) until hatching, which takes approximately 53–63 days (Fig. 2). To maintain a constant temperature of c. 29.5 °C in the incubators, temperatures were monitored by data loggers (Stoway TidbiT Onset ±0.3 °C) placed in the incubators. Temperature data were downloaded from the data loggers every 4 days, and, if necessary, the incubator temperatures were adjusted accordingly. Each plastic container was covered with a plastic lid. Each incubator contained six eggs (from two different females). One container was used as a control and the Ergoloid eggs were not exposed to fungal inoculum. In the other container, the eggs were challenged with inoculum. The inoculum consisted of egg shells previously incubated for 24 h at room temperature with conidia of the cultured F. solani isolate (001AFUS). Four pieces of the inoculum (c. 1 cm × 1 cm) were added to the upper side of the healthy eggs placed in the incubators (Fig. 2). The eggs were exposed to the inoculum on day 36 of incubation. The experiment was carried out twice. On day 45, the plastic lid was removed and exchanged for perforated polyethylene plastic wrap in order to allow for better oxygenation and to diminish condensation due to the increased embryonic metabolic heating during the last period of incubation (Carr & Hirth, 1961; Miller, 1985).

, 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 Lapatinib ic50 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 Pexidartinib 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 Epothilone B (EPO906, Patupilone) 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.

“
“A facultative methanotroph, Methylocystis strain SB2, was examined for its ability to degrade chlorinated hydrocarbons when grown on methane or ethanol. Strain SB2 grown on methane degraded vinyl chloride (VC), trans-dichloroethylene (t-DCE), trichloroethylene (TCE), 1,1,1-trichloroethane (1,1,1-TCA), and chloroform (CF), but not dichloromethane (DCM). Growth on methane was reduced in the presence of any chlorinated hydrocarbon. Strain SB2 grown on ethanol degraded VC, t-DCE, and TCE, and 1,1,1-TCA, but not

DCM or CF. With the exception of 1,1,1-TCA, the growth of strain SB2 on ethanol was not affected by any individual chlorinated hydrocarbon. No degradation of any chlorinated hydrocarbon was observed when acetylene was added to ethanol-grown cultures, indicating that this degradation was due to particulate MG-132 methane monooxygenase (pMMO) activity. When mixtures of chlorinated alkanes or alkenes were added to cultures growing on methane or ethanol, chlorinated alkene degradation PD0332991 in vivo occurred, but chlorinated alkanes were not, and growth was reduced on both methane and ethanol. Collectively, these data indicate that competitive inhibition of pMMO activity limits methanotrophic growth

and pollutant degradation. Facultative methanotrophy may thus be useful to extend the utility of methanotrophs for bioremediation as the use of alternative growth substrates allows for pMMO activity to be focused on pollutant degradation. Methanotrophs are a group of phylogenetically diverse bacteria that consume methane, and as such, play a critical role in the global carbon cycle (Semrau et al., 2010). Until recently, it was believed

that methanotrophs were functionally quite limited, being able to only utilize a small range of compounds for growth, for example, methane and methanol, and could not utilize multicarbon compounds as the sole sources of carbon and energy. Several studies, however, have found that a variety of acidophilic and mesophilic methanotrophs in the Alphaproteobacteria can indeed grow facultatively, i.e., on a variety of small organic acids and ethanol (Dedysh et al., 2005; Venetoclax price Dunfield et al., 2010; Belova et al., 2011; Im et al., 2011). Of these facultative methanotrophs, Methylocystis strain SB2 and Methylocystis strain H2s have been shown to constitutively express the particulate methane monooxygenase (pMMO) regardless of the growth substrate (Belova et al., 2011; Yoon et al., 2011). Such a finding is intriguing as methanotrophs have been shown to be able to oxidize priority pollutants such as halogenated hydrocarbons via pMMO activity (Lontoh & Semrau, 1998; Han et al., 1999; Lee et al., 2006). As described earlier (Yoon et al., 2011), pollutant degradation via facultative methanotrophy may enhance bioremediation strategies, given the greater solubility of the alternative growth substrates (i.e.

coli (EHEC) (Yu et al., 2010). Expression from a higher http://www.selleckchem.com/products/bgj398-nvp-bgj398.html copy-number plasmid in either the wild type or mutant backgrounds caused autolysis, reminiscent of the effects of overexpressing major peptidoglycan-degrading enzymes, and reduced the expression of a number of T3S components (Yu et al., 2010). Interactions of components of macromolecular complexes with peptidoglycan-degrading enzymes could assist in the spatial control of their activity. For example, VirB1 is the LT associated with the T4S system from A. tumefaciens and B. suis (Baron et al., 1997; Hoppner et al., 2004). VirB1 interacts with the VirB4 ATPase

situated in the inner membrane (Ward et al., 2002; Draper et al., 2006). Its processed and secreted VirB1* C-terminus, which lacks LT activity, may associate with a component of the

periplasm-spanning channel, VirB9, in addition to being loosely associated with the cell exterior (Baron et al., 1997). These associations with the T4S apparatus would serve to restrict the LT activity of VirB1. As well, it is possible that the specialized LTs are substrates for their associated secretion system, as some lack a discernable Sec secretion signal. They could be secreted by the assembling secretion system into the periplasm at the place and time that their activity is required to create Imatinib a localized gap in the peptidoglycan. In Pseudomonas syringae, the LTs HrpH and HopP1 are both T3S substrates that can be translocated into the host (Oh et al., 2007). In addition to localized peptidoglycan degradation in the bacterium, they may degrade peptidoglycan fragments that were cotranslocated into the host cell,

in order to prevent recognition by Nod and other immune receptors and aiding in the infection process (Oh et al., 2007). FlgJ from S. enterica serovar Typhimurium is secreted into the periplasm by the type III flagellar Exoribonuclease export system and generates breaks in the peptidoglycan sacculus required to complete the formation of the flagellar rod so that further assembly of the flagellum can proceed (Nambu et al., 1999). Although it is the C-terminal domain of FlgJ that is involved in peptidoglycan hydrolysis, it is the essential N-terminal domain that acts to cap the flagellar rod. The N-terminal portion of FlgJ may be important for spatial control of the lytic activity of FlgJ due to its direct interactions with the rod, as the C-terminal domain alone is more active in vitro compared with the full-length protein (Nambu et al., 1999; Hirano et al., 2001). Also, work with a PleA homologue, RSP0072 from Rhodobacter sphaeroides, demonstrated that it interacts with a monofunctional form of FlgJ, which has only a rod-capping function, despite not being exported by the type III flagellar export system (de la Mora et al., 2007).

Our work links Weber’s law with neural firing property quantitatively, shedding light on the relation between psychophysical behavior and neuronal responses. “
“The lateral posterior nucleus (LP) receives inputs from both neocortex and superior colliculus (SC), and is involved with integration and processing of higher-level visual information. Relay neurons in LP contain tachykinin receptors and are innervated by substance P (SP)-containing SC neurons and by layer V neurons of the visual cortex. In this study, we investigated the actions of SP on LP relay neurons using whole-cell recording techniques. SP produced a

graded depolarizing response in LP neurons along the rostro-caudal extent of the lateral subdivision of LP nuclei (LPl), with a significantly larger response in rostral selleck screening library LPl neurons compared with caudal LPl neurons. In rostral LPl, SP (5–2000 nm) depolarized nearly all relay neurons tested (> 98%) in a concentration-dependent manner. Voltage-clamp experiments revealed that SP produced an inward current associated with a decreased conductance.

The inward current was mediated primarily by neurokinin receptor (NK)1 tachykinin receptors, although significantly smaller inward currents were produced by specific NK2 and NK3 receptor agonists. The selective NK1 receptor antagonist RP67580 attenuated the SP-mediated response by 71.5% and was significantly larger than the attenuation of the SP response obtained by NK2 and NK3 receptor antagonists, selleck GR159897 and SB222200, respectively. The SP-mediated response showed voltage characteristics consistent with a K+ conductance, and was attenuated by Cs+, a K+ channel blocker. Our data suggest that CHIR-99021 molecular weight SP may modulate visual information that is being processed and integrated in the LPl with inputs from collicular

sources. “
“One usually fails to recognize an unfamiliar object across changes in viewing angle when it has to be discriminated from similar distractor objects. Previous work has demonstrated that after long-term experience in discriminating among a set of objects seen from the same viewing angle, immediate recognition of the objects across 30–60° changes in viewing angle becomes possible. The capability for view-invariant object recognition should develop during the within-viewing-angle discrimination, which includes two kinds of experience: seeing individual views and discriminating among the objects. The aim of the present study was to determine the relative contribution of each factor to the development of view-invariant object recognition capability. Monkeys were first extensively trained in a task that required view-invariant object recognition (Object task) with several sets of objects.

, 2002; Gutierrez et al., 2005; Romano et al., 2007). Moreover, C. burnetii actively

mediates the inhibition of host cell apoptosis by activating Akt and Erk1/2 (Voth & Heinzen, 2009), allowing this relatively slow-growing pathogen (10–12-h replication rate) the opportunity to replicate to high numbers before host cell lysis. These characteristics may be attributable to C. burnetii proteins containing the ankyrin repeat eukaryotic motifs, which have been shown to associate with the PV membrane, microtubules, and mitochondria when expressed ectopically within eukaryotic cells (Voth et al., 2009). In addition, recent reports show a series of C. burnetii-encoded ankyrin repeat domain-containing proteins that are secreted

into host cells by Legionella pneumophila in a type IVB secretion selleck compound system (T4BSS)-dependant manner (Pan et al., 2008; Voth et al., 2009), highlighting the versatility and importance of this secretion system. Bacterial secretion systems specifically involved in virulence include the type IV secretion systems (T4SS). The T4SSs have been subdivided into two groups: the type IVA secretion system (T4ASS), encoded by the virB operon (Sexton & Vogel, 2002), and the T4BSS (Segal et al., 1998; Vogel et al., 1998). Legionella pneumophila’s T4BSS is essential for effector protein secretion, bacterial intracellular trafficking, and replication within macrophages as well as amoeba (Marra et al., 1992; Berger & Isberg, 1993; Bruggemann et al., 2006; Ninio & Roy, 2007; Shin & Roy, 2008). Analysis of the C. burnetii RSA 493 (Nine Mile AZD9668 datasheet phase I strain) genome sequence revealed loci with

significant homology Y-27632 supplier and gene organization to both region I (RI) and region II of the L. pneumophila T4BSS (Seshadri et al., 2003). The genomic sequence, combined with studies using C. burnetii T4BSS analogs (IcmW, DotB, IcmS, and IcmT) to complement L. pneumophila mutants (Zamboni et al., 2003; Zusman et al., 2003), indicates that C. burnetii expresses a functional T4BSS during infection. Gene expression analysis of the C. burnetii T4BSS has been limited both in the number of homologs analyzed as well as the breadth of the temporal analysis. In an effort to develop an understanding of the transcriptional and translational expression of the C. burnetii T4BSS with an emphasis on early stages of the infectious cycle, we analyzed the RNA expression profile of select RI genes. The C. burnetii T4BSS RI loci contains 12 genes (CBU1652–CBU1641), nine of which are L. pneumophila T4BSS homologs (Seshadri et al., 2003). Following a synchronous infection of host cells by C. burnetii SCVs, total RNA isolated during the initial stages of the infectious cycle was used to analyze the transcription of the C. burnetii T4BSS RI homologs. Here, we provide the first demonstration of the transcriptional linkages between the C.

Homologous systems were identified in the genomes of distinct taxonomic groups of Bacteria and Archaea, which provides

evidence that horizontal gene transfer has contributed to the wide dissemination of R-M modules – even between domains. Analysis of the cleavage specificity of the R.PamI endonuclease revealed that this protein is an isoschizomer of restriction enzyme NcoI. Interestingly, bioinformatic analyses suggest that R.PamI and NcoI are accompanied by methyltransferases of different methylation specificities (C5-methylcytosine and N4-methylcytosine methyltransferases, respectively), which possibly exemplifies recombinational shuffling of genes coding for individual components of R-M systems. The PamI system can stabilize plasmid pAMI7 in a bacterial population, most probably at the postsegregational level. Therefore, it functions in an analogous manner to plasmid-encoded PXD101 price toxin-antitoxin (TA) systems. Since the TA system

of pAMI7 is nonfunctional, it is highly RG7420 research buy probable that this lack is compensated by the stabilizing activity of PamI. This indicates the crucial role of the analyzed R-M system in the stable maintenance of pAMI7, which is, to our knowledge, the first report of ‘symbiosis’ between a R-M system and a plasmid in the Alphaproteobacteria. Restriction-modification (R-M) systems are exclusive to unicellular organisms and are ubiquitous in the bacterial world. These systems encode (1) a restriction endonuclease (REase), which recognizes a specific DNA sequence and introduces a double-strand break, and (2) a cognate DNA methyltransferase (MTase) that transfers the methyl group from S-adenosyl-l-methionine

(AdoMet) onto specific nucleobases within the same target, thereby protecting it from cleavage. Methylation of DNA occurs either at adenine or cytosine, yielding N6-methyladenine (m6A), N4-methylcytosine (m4C) or C5-methylcytosine (m5C). The m4C and m6A DNA MTases, which modify exocyclic NH2 groups, next are grouped together as N-MTases (Tock & Dryden, 2005). Based on their genetic and biochemical characteristics, R-M systems have been classified into four types (I–IV) (Roberts et al., 2003). The vast majority (more than 3800) of the systems belong to type II, which comprises two-gene genetic modules encoding separate proteins: MTase and REase. Both enzymes recognize a specific short nucleotide sequence (commonly a palindrome) and the REase cleaves double-stranded DNA at specific sites within or adjacent to these sequences (Roberts et al., 2003). It is widely believed that the R-M modules act as ‘a natural bacterial immune system’ which discriminates ‘self ’ (methylated) DNA from ‘foreign’ (not protected by methylation) DNA acquired by horizontal gene transfer. These systems are therefore efficient tools for defense against infection by viral, plasmid, and other exogenous DNA (Tock & Dryden, 2005).