0) or a low (55) pH The bacteria grew at pH 90, but biofilm fo

0) or a low (5.5) pH. The bacteria grew at pH 9.0, but biofilm formation was abrogated, especially

in the presence of 5% serum. Interestingly, at pH 5.5, biofilm formation was significantly greater in TSB+5% serum than at a neutral pH. EAP was still required for biofilm formation at pH 5.5, but Nptase was not required (Fig. 2). This effect may be due to alterations in the charge properties of extracellular proteins and a subsequent alleviation of the requirement for Nptase to anchor EAP to the bacterial cell surface. To confirm the role for EAP and Nptase in biofilm formation in the presence of serum, we transduced the eap and nptase deletion mutations to an additional Protein Tyrosine Kinase inhibitor strain of S. aureus, 10833, and complemented the mutations in trans by cloning the genes into an IPTG-inducible plasmid. One millimolar of IPTG was sufficient to restore

biofilm formation in the presence of serum (Supporting Information, Fig. S1), and this concentration complemented the expression of the genes as demonstrated by RT-PCR (Fig. 3) and by phosphatase assay (Fig. S2). Strain 10833 was a weaker biofilm former Ku-0059436 supplier than SA113, but, nonetheless, the deletion mutations had a significant effect on biofilm-forming activity in the presence of 5% serum (Fig. 4). While the eap and nptase deletion mutants were defective for biofilm formation in TSB containing 5% serum, complementation of the genes restored the phenotype, confirming that the eap and nptase mutations were responsible for the effect (Fig. 4). The finding that EAP only played a role in the presence of serum suggested that serum proteins such as fibronectin and fibrinogen, which have been shown to bind to EAP (Palma et al., 1999), could contribute to the formation of a biofilm on polystyrene. The role for Nptase in biofilm formation is likely due to its ability to dock EAP to the bacterial cell surface. In sum, these results indicate Ceramide glucosyltransferase that EAP and Nptase contribute to biofilm formation in the presence of 5% human serum. The effect of serum suggests a role for EAP not only for

aggregation and adherence to host tissues in vivo but also for biofilm formation during infection as well. Intravenous catheters and other inserted synthetic medical devices are exposed to blood components and extracellular matrix proteins that are recognized by EAP. Therefore, EAP may play an important role in the formation of a biofilm on these surfaces. The pH of the growth medium played a role as well, in that low pH augmented biofilm formation in the presence of serum and alleviated the requirement for Nptase. While pH 5.5 is not physiologically relevant, this finding suggests that the charge properties of extracellular bacterial proteins and possibly of serum proteins are important in the process of EAP-mediated biofilm formation.

They represent the most important food crop in Uganda, Rwanda and

They represent the most important food crop in Uganda, Rwanda and Burundi and are significant as a cash crop and staple food throughout the Great Lakes region of East Africa. Uganda is the second largest producer of bananas/plantains (after India) according to statistics from the Food and Agriculture Organisation of the United Nations (http://faostat.fao.org cited by Biruma et al., 2007 and Vurro et al., 2010). Since 2001, the emergence of banana Xanthomonas wilt (BXW) disease has threatened the

livelihoods of tens of millions of East-African farmers (Tushemereirwe et al., 2004; Biruma et al., 2007). The disease has been known in Ethiopia on enset (Ensete ventricosum), a close relative of banana, since the 1960s (Shimelash et al., 2008). However, BXW has recently spread

to the Burundi, the Democratic Republic of Congo, Kenya, Rwanda, Tanzania and Uganda (Tushemereirwe et al., 2004; Ndungo et al., 2006; Biruma et al., 2007; Reeder et TGF-beta inhibitor al., 2007; Carter et al., 2010). The disease is characterized by premature ripening of fruits, internal brown discoloration of fruits and vascular tissues, wilting of bracts and male buds and progressive yellowing leading to complete wilting. Once established in an area, BXW spreads rapidly and often leads to complete loss of yield (Biruma et al., 2007). The etiologic agent of BXW is a Gram-negative bacterium, previously classified as Xanthomonas campestris pathovar musacearum (Xcm) (Young et al., 1978). A recent phylogenetic study (Aritua et al., 2008) suggested that rather than belonging to species X. campestris, the bacterium is more closely related to the selleck inhibitor species

Xanthomonas vasicola, which includes pathovars X. vasicola pathovar holcicola (Xvh) pathogenic to sorghum and X. vasicola pathovar vasculorum (Xvv) pathogenic to sugarcane (Saccharum officinarum) Farnesyltransferase and maize (Zea mays) (Ohobela & Claflin, 1987; Vauterin et al., 1992, 1995). Accordingly, Xcm can be considered as a new pathovar of species X. vasicola (Aritua et al., 2008). Aritua et al. (2008) also showed that strains of Xvh and Xvv were nonpathogenic on banana but were pathogenic on maize, whereas Xcm strains were pathogenic on both banana and maize. These pathogenicity data suggest a host-jump by a strain of Xvh or Xvv onto a Musa species, because the Xcm strains retained pathogenicity to maize (Aritua et al., 2008). Xanthomonas is a genus within the Gammaproteobacteria that includes >20 species and hundreds of pathovars of Gram-negative rod-shaped plant-pathogenic bacteria (Vauterin et al., 1995). This genus includes causative agents of several economically important diseases. Complete genome sequences have been determined for several members of the genus (da Silva et al., 2002; Lee et al., 2005; Qian et al., 2005; Thieme et al., 2005; Salzberg et al., 2008; Vorholter et al., 2008; Pieretti et al., 2009; Moreira et al., 2010). However, no complete genome sequence is available for X.

Eleven of the 55 secondary metabolite clusters were upregulated a

Eleven of the 55 secondary metabolite clusters were upregulated at the lower temperature, including aflatoxin biosynthesis genes, which were among the most highly upexpressed genes. On average, transcript abundance for the 30 aflatoxin biosynthesis genes was 3300 times greater at 30 °C as compared with 37 °C. The results are consistent with the

view that high temperature negatively affects MI-503 manufacturer aflatoxin production by turning down transcription of the two key transcriptional regulators, aflR and aflS. Subtle changes in the expression levels of aflS to aflR appear to control transcription activation of the aflatoxin cluster. Aspergillus flavus produces aflatoxins B1 and B2 and causes aflatoxin contamination of preharvest crops such as corn, cotton, peanuts and tree nuts, and postharvest grains during storage (Bhatnagar et al., 1987; Bennett & Klich, 2003). The discovery of the first stable aflatoxin precursor, norsolorinic acid (Bennett, 1981), paved the way

for the elucidation of the aflatoxin biosynthetic pathway, including its intermediates and biosynthetic gene clusters in A. flavus, Aspergillus parasiticus, Aspergillus nidulans (sterigmatocystin as end product), Aspergillus sojae and Aspergillus oryzae (nonfunctional gene cluster) (Brown et al., 1996; Yu et al., 2004a, b). Aflatoxin biosynthesis is affected by many biotic and abiotic factors (Payne & Brown, 1998; Yu et al., 2010). The influence of temperature C1GALT1 on aflatoxin formation has been reported previously (Schroeder & Hein, 1968; Ogundero, 1987). The optimum BIBW2992 temperature for biosynthesis of aflatoxin and other secondary metabolites is at 30 °C; while the optimum temperature for fungal growth is at about 37 °C but it is less optimal for mycotoxin production. Sequencing of the A. flavus genome facilitated the construction of microarrays, which have been used to study transcriptional

regulation of aflatoxin biosynthesis at different temperatures (OBrian et al., 2007; Georgianna et al., 2008, 2010; Payne et al., 2008; Schmidt-Heydt et al., 2009). These studies identified a large number of genes expressed at high level under low temperature. The effect of temperature on natural antisense transcript expression was also reported (Smith et al., 2008). While microarrays are a robust tool for genome-wide gene expression analysis, they have been plagued by high background and low sensitivity problems. For regulatory genes with low level of expression, microarrays often fail to provide meaningful information about their expression levels. Thus, no published microarray experiments have provided an accurate estimate of the aflR and aflS expression levels. RNA-Seq technology has been successful for transcriptome profiling in a closely related species, A. oryzae (Wang et al., 2010).

Eleven of the 55 secondary metabolite clusters were upregulated a

Eleven of the 55 secondary metabolite clusters were upregulated at the lower temperature, including aflatoxin biosynthesis genes, which were among the most highly upexpressed genes. On average, transcript abundance for the 30 aflatoxin biosynthesis genes was 3300 times greater at 30 °C as compared with 37 °C. The results are consistent with the

view that high temperature negatively affects find more aflatoxin production by turning down transcription of the two key transcriptional regulators, aflR and aflS. Subtle changes in the expression levels of aflS to aflR appear to control transcription activation of the aflatoxin cluster. Aspergillus flavus produces aflatoxins B1 and B2 and causes aflatoxin contamination of preharvest crops such as corn, cotton, peanuts and tree nuts, and postharvest grains during storage (Bhatnagar et al., 1987; Bennett & Klich, 2003). The discovery of the first stable aflatoxin precursor, norsolorinic acid (Bennett, 1981), paved the way

for the elucidation of the aflatoxin biosynthetic pathway, including its intermediates and biosynthetic gene clusters in A. flavus, Aspergillus parasiticus, Aspergillus nidulans (sterigmatocystin as end product), Aspergillus sojae and Aspergillus oryzae (nonfunctional gene cluster) (Brown et al., 1996; Yu et al., 2004a, b). Aflatoxin biosynthesis is affected by many biotic and abiotic factors (Payne & Brown, 1998; Yu et al., 2010). The influence of temperature Selleck 5-Fluoracil on aflatoxin formation has been reported previously (Schroeder & Hein, 1968; Ogundero, 1987). The optimum check details temperature for biosynthesis of aflatoxin and other secondary metabolites is at 30 °C; while the optimum temperature for fungal growth is at about 37 °C but it is less optimal for mycotoxin production. Sequencing of the A. flavus genome facilitated the construction of microarrays, which have been used to study transcriptional

regulation of aflatoxin biosynthesis at different temperatures (OBrian et al., 2007; Georgianna et al., 2008, 2010; Payne et al., 2008; Schmidt-Heydt et al., 2009). These studies identified a large number of genes expressed at high level under low temperature. The effect of temperature on natural antisense transcript expression was also reported (Smith et al., 2008). While microarrays are a robust tool for genome-wide gene expression analysis, they have been plagued by high background and low sensitivity problems. For regulatory genes with low level of expression, microarrays often fail to provide meaningful information about their expression levels. Thus, no published microarray experiments have provided an accurate estimate of the aflR and aflS expression levels. RNA-Seq technology has been successful for transcriptome profiling in a closely related species, A. oryzae (Wang et al., 2010).

Hybridization and washing procedures were carried out as describe

Hybridization and washing procedures were carried out as described previously (Tobino et al., 2011). Chemiluminescent detection was performed using an antidigoxigenin antibody conjugated with alkaline phosphatase and CSPD (both Roche) according to the instruction manual (DIG Application Manual for Filter Hybridization, Roche), and the signal was Decitabine recorded by LAS-4000 mini (Fujifilm, Tokyo, Japan) using a 10 min exposure. Signals were background corrected and considered positive when the signal to noise ratio was > 3 in all the replicated

spots. Partial sequences from both ends (60–700 bp) of each probe were read using SP6 and T7 primers as described previously (Tobino et al., 2011). The full probe sequence was defined as the segment that was on and within both end sequences in the genome, found using the blastn tool from the National Center for Biotechnology Information (NCBI). Saracatinib molecular weight The full probe sequences were then searched against the target genome sequences using

blastn in NCBI under the default settings. The match that had the least e-value was selected as the representative similarity pair between the probe and the target genome. To eliminate short alignments and anomalous high signals, caused by the high gene copy number, those pairs that had < 500 bp alignment or significant multiple hits were rejected in the subsequent analysis. Specific responses were observed from probes corresponding to the target genome at all hybridization temperatures tested (Fig. S2). Visible signals were also found from some probes whose origins were different from the target genome, Doxacurium chloride indicating the occurrence

of cross-hybridization (i.e. false positives). As shown in Table 1, the level of false positive signals was 64.7% (216 of 334) at 55 °C but decreased steadily to 22.5% (75 of 334) at 70 °C and was almost completely absent (1.5%; 5 of 334) at 75 °C. In contrast, very few probes (0.6%; 1 of 167) corresponding to the target genome fell in negative and were only found at hybridization temperatures above 70 °C. These results suggest that randomly generated genomic fragments (~ 2000 bp) can function as specific probes to discriminate species in the genus Pseudomonas under highly stringent conditions. Sequence similarity searches between the fragment probes and target genomes produced a total of 496 similarity pairs (Fig. S3). With the exception of probes that originated from the target genome (resulting in 100% similarity), most of the pairs had < 90% similarity, while only two pairs sharing a partial sequence of rrn operon were found to have > 90% similarity of > 500 bp.

Seventy-three control participants were recruited from the local

Seventy-three control participants were recruited from the local community. Both groups differed with respect to age, gender and marital status (P < 0.001), while education and socio-economic levels were similar. Ixazomib solubility dmso HRQoL was assessed using the Short Form-36 (SF-36) and depressive symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9). A multivariate analysis of covariance found that RA patients reported substantially higher depressive symptoms and lower HRQoL than healthy controls (P < 0.01 and P < 0.05, respectively). The effect sizes

of the differences between patients and controls in HRQoL and depressive symptoms were all large. All SF-36 HRQoL variables were significantly correlated with depressive symptoms in patients and controls (P < 0.05). Y-27632 molecular weight Social functioning and vitality were uniquely associated with depressive symptoms in the RA group (P < 0.01 and P < 0.05, respectively), whereas education and social functioning were uniquely associated with depressive symptoms in controls (P < 0.05 and P < 0.005, respectively). Research indicates that individuals with RA have deteriorated HRQoL, and this study extends these findings to a Colombian sample and highlights the importance of the independent

relationship between depressive symptoms and vitality in this group of Colombians with RA. “
“The concept of a pharmacist/advanced practice nurse (APN)-led Rheumatology Monitoring Clinic (RMC) is a novel service in Singapore; we therefore conducted a questionnaire survey of patient experience. Patients attending the RMC were provided with a set of questionnaires. As a substudy, a separate questionnaire was given to the rheumatologists and therapists conducting the RMC. Of the 105 patients surveyed, a total of 97 (92.4%) patients were satisfied/strongly satisfied with the overall service, and none were dissatisfied; 96% felt that the pharmacists/APNs provided clear, detailed information about Ponatinib their disease and medication, while 92% of patients were confident they knew what side-effects were possible. Ninety-two percent and 93% of patients were more likely to adhere to treatment,

and were willing to come back for follow-up at the RMC, respectively. There was no difference in patient satisfaction in the average Likert summed scores, between the pharmacists and APNs. Age, gender, ethnicity and underlying disease did not exert any influence on the responses. All the rheumatologists surveyed were satisfied with the patients’ management and the professionalism of the therapists. They opined that the RMC freed up time for them to see more complex cases. All the pharmacists/APNs concurred that the referrals were appropriately selected. We established the acceptability of a non-physician-led clinic in our local setting and highlighted the usefulness of having a routine clinic for monitoring medication toxicity and patient education.

The acid resistance

assay of Castanie-Cornet et al (1999

The acid resistance

assay of Castanie-Cornet et al. (1999), as modified by David Graham (Giles & Graham, 2007), was utilized. Acid resistance was expressed as the percentage of viable bacteria remaining after one-hour acid shock compared to the number of viable bacteria determined immediately following acid shock. The highly conserved chlamydial AaxB peptide 137HAKMWLKKSLQHELDLRS154 (part of the α subunit) was commercially synthesized by Pierce Custom Antibody Production Service and used to raise polyclonal rabbit antibodies using the standard 90-day protocol. Escherichia coli Rosetta-gami2 (DE3) was transformed with pET-19b carrying aaxB from C. caviae and grown in LB containing 100 μg mL−1 ampicillin to an OD600 nm of 0.6. AaxB expression was induced with 1 mM IPTG for 23 h at 20 °C, and bacteria were collected by centrifugation. Bacteria were resuspended in equilibration Cabozantinib nmr buffer (50 mM monobasic sodium phosphate, 300 mM sodium chloride, and 10 mM imidazole, pH adjusted to 7.4) with 1× protease inhibitor (Roche) and 1× phosphatase inhibitors 2 and 3 (Sigma). Bacteria were lysed via sonication, centrifuged to remove

debris, and the supernatant passed through a 0.45-μm Doxorubicin supplier filter (Millipore). HisPur™ cobalt resin (Thermo Scientific) was applied to the supernatant, and the batch method of purification was carried out as per manufacturer’s instructions. Purified protein samples were eluted (50 mM sodium phosphate, 300 mM sodium chloride,

500 mM imidazole, pH adjusted to 7.4) and then applied to a 3K Amicon filter (Millipore) for concentration. Samples were resuspended in 50 mM Bis–Tris buffer (pH 6.0) and quantified by the Bio-Rad Protein Assay (Bio-Rad). Protein identity and purity were assessed using SDS-PAGE followed by Coomassie Brilliant Blue Staining or Western blotting with the anti-AaxB antibody (at a 1:250 dilution). Chlamydia were grown in and harvested from mouse fibroblast L2 cells. EBs were titered using an infection-forming unit assay (IFU) and stored at -80 °C in sucrose–phosphate–glutamic acid buffer (SPG; 7.5% w/v sucrose, 17 mM Na2HPO4, 3 mM NaH2PO4, 5 mM l-glutamic acid, pH 7.4) until use (Binet et al., 2010). For not time course experiments, L2 cells were infected at a MOI of 5 (10-h samples) and MOI of 1 (20-, 30-, and 44-h samples), or mock-infected (Giles et al., 2009). Samples were disrupted directly in Laemmli buffer and run on 12% SDS-PAGE gels for Western blot analysis with either anti-AaxB antibodies or anti-Hsp60 antibodies (provided by Dan Rockey, Oregon State University; Yuan et al., 1992). Detection of Hsp60 (60 kDa heat shock protein, GroEL) was used to demonstrate successful infection and equal loading of protein. To detect AaxB in EBs, bacteria were disrupted in Laemmli buffer, and 1 × 107 IFU was used per SDS-PAGE gel lane. The AaxB sequences from the available Chlamydia genome projects were aligned to assess amino acid variability.

Instead, regulation of hrp regulon by prhK, prhL, and prhM appear

Instead, regulation of hrp regulon by prhK, prhL, and prhM appears to be indirect. We think it is important to understand how PrhK, PrhL, and PrhM regulate hrpB expression and will give this research priority in the future. The expression level of prhG in the prhK, prhL, and prhM

Metformin mutants was limited to approximately one-tenth of that in the wild type (Table 2). These mutants lost pathogenicity toward tomato (Fig. 2a), just like the hrpG mutant. On the other hand, the prhG mutant itself is slightly less virulent than the wild type (Plener et al., 2010). While HrpG controls the expression of a number of virulence determinants and genes involved in adaptation to life in the host plant, PrhG controls very few specific targets other than the hrp regulon through hrpB activation (Valls et al., 2006; Plener et al., 2010). Therefore, we speculate that PrhKLM controls not only the prhG gene and the hrp regulon, but also other pathogenesis-related genes. Judging from the colony morphology and microscopic observation, exopolysaccharide production and motility in the prhKLM mutants were normal (data not shown). Genes for T2SS and Regorafenib concentration genes encoding several extracellular plant cell wall-degrading enzymes, such as polygalacturonases,

β-1,4-endoglucanase, and pectin methylesterase, are major virulence determinants (Mole et al., 2007). The aim is to monitor the expression levels of these genes in prhKLM mutants in the future

to further investigate PrhKLM-controlled genes. In conclusion, we have isolated a novel class of pathogenesis-related genes. These genes are common among nonpathogenic bacteria from the genera Ralstonia and Burkholderia. The regulation mechanism of hrp regulon by these genes is still speculative. In the future, we plan to further elucidate the functions of PrhK, PrhL, and PrhM. This work was supported in part by Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (16658020 to Y.H. and 17380031 to K.O.). Fig. S1. Cell growth in the stem. Table S1. Primers used in this study. Appendix S1. Materials and methods. Please note: Wiley-Blackwell is not responsible for the content or functionality of any supporting materials supplied by the Selleckchem Fludarabine authors. Any queries (other than missing material) should be directed to the corresponding author for the article. “
“Highly active antiretroviral therapy (HAART) leads to immune reconstitution, as demonstrated by a substantial increase in CD4 T-lymphocyte count, which can happen even in patients with advanced HIV disease and severe immunodepression [1]. However, up to 40% of HIV-infected patients are ‘immunological nonresponders’; that is, they have discordant responses to long-term HAART characterized by complete suppression of HIV replication in the absence of a significant increase in CD4 T-cell count [2,3].

During the two past decades, a large variety of therapeutic molec

During the two past decades, a large variety of therapeutic molecules has been successfully expressed in LAB, and although this field has been largely Enzalutamide reviewed in recent years, approximately 20 new publications appear each year. Thus, the aim of this minireview is not to extensively assess the entire literature but to update progress made within the last 2 years regarding the use of the model LAB Lactococcus lactis and certain species of lactobacilli as live recombinant vectors for the development of new safe mucosal vaccines. “
“Tn6000 (formerly EfcTn1) from Enterococcus

casseliflavus strain 664.1H1 (previously Enterococcus faecium 664.1H1) is a tetracycline resistance-encoding conjugative transposon of the Tn916-like family of mobile genetic elements. Sequence analysis of Tn6000 shows that it has a novel modular structure, comprising fragments of diverse proven and putative mobile elements including plasmids, conjugative transposons and virulence and pathogenicity islands. Antibiotic resistance among Gram-positive nosocomial pathogens continues to be a major global public health burden (Woodford & Livermore, 2009). Enterococcus spp. are an increasingly common cause of nosocomial infections, with Enterococcus faecalis and Enterococcus faecium accounting for the majority of outbreaks. Other Enterococcus spp., including

Enterococcus casseliflavus, have also been shown to be pathogenic to humans. Antibiotic resistance genes in this genus are present on a variety of mobile genetic elements, allowing Enterococcus spp. to accrue multiple selleck kinase inhibitor resistances (Paulsen et al., 2003; Davis et al., 2005). Conjugative transposons are one of the most important mediators of spread of resistance. Conjugative transposons, also known as integrative conjugative elements (Roberts et al., 2008), are responsible for broad host-range transfer of resistance genes in many Gram-positive bacteria. The prototype element from one family of conjugative transposons is Tn916 (Roberts & Mullany, 2009), an 18 kb element conferring tetracycline resistance by Tet(M) (Flannagan et al., 1994). Conjugative

transposons of the Tn916 family have a modular structure. A module is defined as a gene or a set of genes involved in Endonuclease a particular function. In Tn916, the functional modules are for recombination (excision and insertion), transcriptional regulation, conjugation and accessory functions; often, but not exclusively, antibiotic resistance (Roberts & Mullany, 2009). Different Tn916-like elements have been discovered that differ in a particular module, for example Tn5397 shares homology to Tn916 across its length apart from the recombination module; in Tn5397, a large serine recombinase, TndX, is responsible for recombination, whereas in Tn916 the integrase IntTn and excisionase XisTn perform a comparable function (Wang et al., 2000).

During the two past decades, a large variety of therapeutic molec

During the two past decades, a large variety of therapeutic molecules has been successfully expressed in LAB, and although this field has been largely check details reviewed in recent years, approximately 20 new publications appear each year. Thus, the aim of this minireview is not to extensively assess the entire literature but to update progress made within the last 2 years regarding the use of the model LAB Lactococcus lactis and certain species of lactobacilli as live recombinant vectors for the development of new safe mucosal vaccines. “
“Tn6000 (formerly EfcTn1) from Enterococcus

casseliflavus strain 664.1H1 (previously Enterococcus faecium 664.1H1) is a tetracycline resistance-encoding conjugative transposon of the Tn916-like family of mobile genetic elements. Sequence analysis of Tn6000 shows that it has a novel modular structure, comprising fragments of diverse proven and putative mobile elements including plasmids, conjugative transposons and virulence and pathogenicity islands. Antibiotic resistance among Gram-positive nosocomial pathogens continues to be a major global public health burden (Woodford & Livermore, 2009). Enterococcus spp. are an increasingly common cause of nosocomial infections, with Enterococcus faecalis and Enterococcus faecium accounting for the majority of outbreaks. Other Enterococcus spp., including

Enterococcus casseliflavus, have also been shown to be pathogenic to humans. Antibiotic resistance genes in this genus are present on a variety of mobile genetic elements, allowing Enterococcus spp. to accrue multiple www.selleckchem.com/products/napabucasin.html resistances (Paulsen et al., 2003; Davis et al., 2005). Conjugative transposons are one of the most important mediators of spread of resistance. Conjugative transposons, also known as integrative conjugative elements (Roberts et al., 2008), are responsible for broad host-range transfer of resistance genes in many Gram-positive bacteria. The prototype element from one family of conjugative transposons is Tn916 (Roberts & Mullany, 2009), an 18 kb element conferring tetracycline resistance by Tet(M) (Flannagan et al., 1994). Conjugative

transposons of the Tn916 family have a modular structure. A module is defined as a gene or a set of genes involved in Pyruvate dehydrogenase a particular function. In Tn916, the functional modules are for recombination (excision and insertion), transcriptional regulation, conjugation and accessory functions; often, but not exclusively, antibiotic resistance (Roberts & Mullany, 2009). Different Tn916-like elements have been discovered that differ in a particular module, for example Tn5397 shares homology to Tn916 across its length apart from the recombination module; in Tn5397, a large serine recombinase, TndX, is responsible for recombination, whereas in Tn916 the integrase IntTn and excisionase XisTn perform a comparable function (Wang et al., 2000).