Obviously, the spine is a modifiable compartment whose neck length can be controlled by afferent activity and which can regulate the spread of the [Ca2+]i rise evoked at the synapse and perhaps prevent further spreading into the parent dendrite (Korkotian & Segal, 2007); it can also control the access of synaptic molecules into the sphere of the spine head. One category of molecule which is delivered into and out of the synapse in relation

to activity is the ionotrophic AMPA-subtype glutamate receptor. LTP is assumed GSI-IX order to involve the addition of glutamate receptors into the postsynaptic density, and LTD results from the removal of AMPA receptors from the spine head. Recently it has been suggested (Korkotian & Segal, 2007; Ashby et al., 2006) that the spine neck is a barrier to the diffusion of glutamate receptors into the synapse. Whether this barrier is determined by the calcium signal delivered to the dendrite or by the diffusion of receptor molecules is less Z-VAD-FMK price critical; the outcome is that spine neck restricts access of glutamate receptors to the synapse. Consequently, synapses on the parent dendritic shaft should produce larger synaptic currents than those in the spine head, and the length of the spine will determine synapse efficacy. In addition to the influx of calcium through NMDA-gated channels, voltage-gated calcium channels and GluR1-gated,

GluR2-lacking channels, the spines are endowed with calcium stores of the ryanodine type, which are activated by influx of calcium or by direct activation of the ryanodine receptors (e.g. by caffeine). These stores have been linked oxyclozanide recently to the spine apparatus, en enigmatic structure in the spine neck, via synaptopodin, a molecule found to be in close association with the spine apparatus (Vlachos et al., 2009). Synaptopodin and the spine apparatus have been found primarily in large, mature spines. Thus, it is likely that synaptopodin regulates the levels of ambient [Ca2+]i, which is raised transiently by influx of calcium ions. It is likely that large spines, where a larger influx of calcium is expected, need the

stores in order to regulate excess amount of [Ca2+]i. Whether synaptopodin contributes to the stability of the spine is not entirely clear, as time-lapse imaging of synaptopodin and spines show that neither entity is stable over time (Vlachos et al., 2009). Regardless of their plastic properties, spines have been shown to constitute an independent physical compartment in which [Ca2+]i can rise to high levels, independent of the parent dendrite, suggesting that the spine protects the parent neuron from uncontrolled rises in [Ca2+]i, which may otherwise activate apoptotic processes leading to cell death (Schonfeld-Dado et al., 2009). In spiny neurons, shaft synapses are more likely to be harmful to the parent neuron than spine synapses.

The risk of developing at least three TMC125 resistance-associated mutations (RAMs) [7,8] was assessed by means of binary logistic regressions models. Univariate and multivariate analyses were performed to estimate crude and adjusted relative risks (odds ratios, 95% confidence intervals and Wald statistic) for gender, age, HIV RNA, CD4 cell count; and NVP, EFV, protease inhibitor (PI) and enfuvirtide (T20) exposure. Moreover, we considered the number of NNRTIs received and the duration

of NNRTI therapy. The level of statistical significance was set at P=0.05. spss 15 for Windows was the statistical software package used for the analyses (SPSS, Chicago, IL, USA). Moreover, we conducted our analysis with the endpoint of having a TBT WGS>2, which has been reported to predict poor virological response to TMC125 in treatment-experienced patients [16]. A total of 5011 sequences obtained from 2955 patients were evaluated. Of these, 1241 subjects (42.0%) were exposed

GSK2118436 chemical structure only to NVP, 1053 (35.6%) only to EFV, and 613 (20.7%) to both NVP and EFV. Of these 2955 patients, 2153 (72.9%) presented with at least one TMC125 RAM. Among the sequences in ARCA, 68% had at least one and 9.8% at least three TMC125 RAMs, whereas 31% showed a WGS>2. Among the samples with at least one RAM for TMC125 (n=3407), the mutations most frequently represented were Y181C (27%), G190A (22.8%), K101E (11.7%) and A98G (9.3%). K103N was present in 53.9% of sequences. V179F, Y181V and G190S were present in 0.3%, 1.0% Decitabine order and 4.9% of sequences, respectively. When at least three TMC125-related mutations were found (n=495), the mutations most frequently represented were G190A Cyclopamine nmr (62%), Y181C (57.6%) and K101E (44%). K103N was present in 44.8% of sequences. V179F, Y181V and G190S were present in 1.4%, 1.0% and 13.5% of sequences, respectively (Fig. 1). Among the samples with TBT WGS>2 (n=1553), the most frequent mutations were Y181C (59.3%), G190A (26.7%) and K101E (17.8%); K103N was found in 40.1% of sequences. We also analysed the association between TMC125 RAMs and exposure to NVP and EFV: these mutations appeared more frequently in NVP- than EFV-treated patients:

90.2% of sequences from patients exposed to NVP vs. 35.2% of sequences from patients exposed to EFV had mutation Y181C, and these percentages were, respectively, 84.7%vs. 43.1% for G190A, 72.7%vs. 49.8% for K101E, 100%vs. 23.5% for Y181V, and 66.7%vs. 33.3% for V179F. G190S appeared more frequently with exposure to EFV (81.4% of sequences) than NVP (43.3% of sequences). Multivariate analysis revealed that male gender and being EFV- or NVP-experienced were associated with statistically significant increases in the risk of developing three or more TMC125 RAMs. CD4 values ≥200 cells/μL and older age (for each additional 10 years) were statistically protective factors, whereas PI and T20 experience and HIV RNA values did not show any statistically significant associations.

Grading: 1C Infants whose mother’s viral load at 36 weeks’ gestational age or at delivery is > 1000 HIV RNA copies/mL despite cART or unknown (and continued until HIV infection has been excluded). Grading: 2D Primary Pneumocystis pneumonia (PCP) in infants with HIV remains a disease with a high mortality and morbidity. However, as the risk CYC202 molecular weight of neonatal HIV infection has fallen to < 1% where

mothers have taken up interventions, the necessity for PCP prophylaxis has declined and in most European countries it is no longer prescribed routinely. However, co-trimoxazole, as PCP prophylaxis, should still be prescribed for infants born to viraemic mothers at high risk of transmission. The infant’s birth HIV molecular diagnostic test (see below) and maternal delivery viral load should be reviewed before the infant is aged 3 weeks. If the HIV molecular diagnostic test taken in the first 24 hours is positive, the infant should be reviewed before 4 weeks for an early repeat test and to be started on co-trimoxazole prophylaxis which should be continued if the HIV infection is confirmed, and stopped if infection is excluded (see section on diagnosis below).

Infants with a first positive HIV molecular diagnostic test at age 6 or 12 weeks should be started on co-trimoxazole prophylaxis until HIV infection is confirmed or excluded (see Table 1 for dose). If the birth HIV diagnostic test is negative, and the maternal delivery www.selleckchem.com/products/LDE225(NVP-LDE225).html viral load is < 1000 HIV RNA copies/mL, there is no need to start co-trimoxazole prophylaxis and

the baby can be seen routinely for a second HIV diagnostic test at age 6 weeks. Co-trimoxazole prophylaxis against PCP is effective, but there are no data on when to initiate it in infants of indeterminate HIV status being followed up after in utero exposure to HIV. A maternal viral load of 1000 HIV RNA copies/mL is an arbitrary cut-off to define infants at higher risk of transmission, in whom it is recommended to start prophylaxis until lack of transmission has been established. 8.3.1 Infants born to HIV-positive mothers should follow the routine national primary immunization schedule. Grading: Sitaxentan 1D Generally, BCG vaccine should only be given when the exclusively formula-fed infant is confirmed HIV uninfected at 12–14 weeks. However, infants considered at low risk of HIV transmission (maternal viral load < 50 HIV RNA copies/mL at or after 36 weeks’ gestation) but with a high risk of tuberculosis exposure may be given BCG at birth. Where the mother is co-infected with hepatitis B virus, immunization against HBV infection should be as per the Green Book and does not differ from management of the HIV-unexposed infant [308]. With sensitivity to concerns about confidentiality, families should be strongly encouraged to inform primary health carers, including midwives, health visitors and family doctors about maternal HIV and indeterminate infants.

The Forskolin in vivo methoxymalonyl-ACP biosynthesis locus, which is composed of fkbGHIJK, was first reported in the FK520 biosynthetic gene cluster (Wu et al., 2000). The roles of fkbGHIJK orthologs in the biosynthesis of methoxymalonyl-ACP

were then substantiated by genetic and biochemical experiments (Fig. 1b) (Kato et al., 2002; Chan et al., 2006; Dorrestein et al., 2006). The methoxymalonyl-ACP biosynthesis locus is generally colocalized with the related modular PKS gene cluster. In the present study, a gene disruption experiment establishes that a methoxymalonyl-ACP biosynthesis locus (galGHIJK) is involved in the biosynthesis of galbonolide A in S. galbus. It is also shown that orf4, which is proximal to galGHIJK and contains a KAS domain, is involved in the biosynthesis of galbonolides A and B. Notably, there is no multimodular PKS gene cluster flanking PD-0332991 cell line these loci, however. Streptomyces galbus KCCM 41354 was acquired from the Korean Culture Center of Microorganisms. Escherichia coli DH5α was used as the host for general subcloning. For total DNA isolation, S. galbus was grown in tryptic soy broth with 10 mM MgCl2·6H2O and 0.5% w/v glycine. Glucose–yeast extract–malt extract (GYM) agar was used for S. galbus spore preparation. Escherichia

coli ET12567 (dam−, dcm−, hsdS−)/pUZ8002 was the nonmethylating plasmid donor strain for the intergeneric conjugative transfer to S. galbus (Flett et al., 1997). GYM agar supplemented with 10 mM MgCl2 was used for the conjugation experiment. Genetic procedures including the gene disruption Ergoloid experiment were performed using standard procedures (Kieser et al., 2000). Southern hybridization

was performed with digoxigenin DNA labeling and a detection kit from Roche Diagnostics (Pleasanton, CA) by following the procedure outlined by the manufacturer. An 800-bp DNA fragment of an fkbI homologue was amplified from the S. galbus chromosome using the PCR and the primer set of 5′-CAGGGCATGGCCGCSTG GACSGT-3′ and 5′-GATGATCTCCATSAGCTTSGCRTC-3′ (Li et al., 2006), which was then cloned into the pGEM-T Easy vector (Promega, Madison, WI). This DNA clone was named pHJK1001. A cosmid library of S. galbus KCCM 41354 genomic DNA was constructed using SuperCos I and the Gigapack III Gold packaging extract kit according to the manufacturer’s handbook (Stratagene, La Jolla, CA). A 3.2-kb KpnI DNA fragment was isolated from the S. galbus genome using the 800-bp fragment in pHJK1001 as a probe, and the presence of methoxymalonyl-ACP biosynthetic genes (galGHI and a truncated galJ) was confirmed by nucleotide sequencing. The 3.2-kb KpnI DNA fragment was then used as a probe in screening the cosmid library, which resulted in the isolation of a positive clone pHJK1011. The 800-bp fragment internal to galI was isolated as an EcoRI fragment from pHJK1001 and ligated into pKC1139 to generate pD-galI, a galI-disruption plasmid. The conjugative plasmid pKC1139 contains an E.

However, Che1-dependent signaling is shown to contribute indirectly to surface attachment, indicating that distinct mechanisms are likely underlying flocculation and attachment to surfaces in A. brasilense. Chemotaxis is a widespread function in motile soil bacteria as it affords cells with the ability to sense and to buy Compound C navigate toward the most favorable niches

for growth (Wadhams & Armitage, 2004). At the molecular level, the chemotaxis pathway is the dedicated chemosensory signal transduction system that allows cells to couple detection of physicochemical changes in their surroundings to changes in the swimming pattern (i.e. chemotaxis). Chemotaxis signal transduction has been best studied in Escherichia coli and experimental evidence indicates that this prototypical enteric model is conserved and functions similarly (with some variations on the theme) in phylogenetically diverse motile bacteria. In addition to regulating chemotaxis responses in motile bacteria, chemotaxis-like signal transduction pathways were shown to regulate cellular behaviors other than flagellar rotation in several other bacterial species (Kirby, 2009), including the alphaproteobacterium Azospirillum brasilense, a soil diazotroph (Bible et al., 2008).

In only a few cases, however, have the molecular targets of these chemotaxis-like pathways been identified. selleck chemicals llc The A. brasilense Che1 chemotaxis-like pathway has been shown to have a minor,

and likely indirect, function in regulating chemotaxis behavior in this species (Hauwaerts et al., 2002; Bible et al., 2008; Edwards et al., 2011). Experimental evidence indicates that Che1 functions to modulate changes in adhesive cell surface properties which impact the propensity for cell-to-cell aggregation and flocculation (Bible et al., 2008). Deletions of cheA1 or cheY1, which each code for central proteins controlling the response output of the signal transduction pathway, yield cells that aggregate and flocculate more than the wild-type strain (Bible et al., 2008). A mutant strain deleted for all of the genes encoded within the che1 gene cluster has a phenotype similar to the strains lacking only CheA1 or CheY1, consistent with a role for Che1 OSBPL9 in regulating the ability of cells to flocculate. A strain carrying a mutation that disrupts the function of both CheB1 and CheR1 is severely impaired in flocculation, consistent with CheB1 and CheR1 functioning in a signaling feedback loop that controls chemosensory adaptation (Stephens et al., 2006; Bible et al., 2008). Other possible roles that Che1 may have on functions such as adhesion to surfaces or root colonization, have been previously proposed to be related to flocculation (Burdman et al., 2000a, b) but have not yet been investigated. The purpose of the present study was to determine the conditions under which A.

For these experiments, in order to obtain sufficient RNA for analysis, the zoocin A and PS-ODNs were added to cultures in log phase growth (as opposed to stationary phase) and at a higher cell density than other

experiments. It was found that use of zoocin A at 0.4 μg mL−1 in these experiments (as opposed to 0.1 μg mL−1, Table 1), resulted in a comparable increase in lag phase to that seen in previous experiments. There were no significant differences (P=0.05) in the transcript levels for either the 16sRNA or gyrA controls in any sample. This shows that the growth inhibition observed in zoocin A- and FBA-treated cultures (Fig. 2) did not result from the induction of a nonspecific ribonuclease. Forskolin Compared with cultures treated with either zoocin A or FBA alone, a significant decrease (P=0.001) in expression of fba was observed at both 30 min (1067.86-fold) and 5 h (2509.16-fold) in cultures treated with zoocin A and FBA. Growth of the culture resumed 4 h after the addition of zoocin A and FBA (Fig. 2), and no significant difference (P=0.05) in values were observed for fba expression levels at times 0 or 16 h, or at any time for any other treatment GKT137831 regime. The drastic reduction in the expression of fba in FBA-treated S. mutans cells was both gene and PS-ODN specific, confirming that the phenotypic

loss of viability observed did not occur as a result of nonspecific cellular toxicity by FBA. Cellular uptake of exogenously added asODNs would facilitate the study of gene function in prokaryotic organisms. In conclusion, this work demonstrated that the bacteriolytic enzyme zoocin

A, used selleck kinase inhibitor at a sublethal concentration, was successful in facilitating the entry of PS-ODNs into streptococcal cells. The degree of inhibition of cell growth, measured as increased lag-phase, was target specific and sensitive to the amount of both zoocin A and PS-ODN used. This work was undertaken with support from the Foundation for Research Science and Technology. “
“The bacterial diversity of seeds, transmission of bacteria from seed to phyllosphere, and fate of seed-transmitted bacteria on mature plants are poorly characterized. Understanding the dynamics of microbial communities is important for finding bio-control or mitigation strategies for human and plant pathogens. Bacterial populations colonizing spermosphere and phyllosphere of spinach (Spinacia oleracea) seedlings and plants were characterized using pyrosequencing of 16S rRNA gene amplicons. Spinach seed microbiota was composed of three bacterial phyla: Proteobacteria, Firmicutes and Actinobacteria, belonging to > 250 different operational taxonomic units (OTUs). Seed and cotyledon bacterial communities were similar in richness and diversity.

In general, the CDC considers travelers to be immunocompromised for 3 months after their last chemotherapeutic treatment.[15] Because the duration of immunosuppression following cancer treatment can vary widely, having specific knowledge of the therapeutic strategies and duration of their associated immunosuppressive effects used in patients with cancer is required. This highlights how in addition to the guidelines, it is crucial to obtain a detailed treatment history in these patients that extends beyond when the last cancer treatment selleck chemical was given, taking into account the current net state of immunosuppression when counseling and administering prophylactic vaccines and medications to this group of travelers.

VFR was the second most common reason for travel in this study. It is well known in the literature that VFR represents a disproportionately higher volume of international travel and VFR travelers are an established

higher risk group less likely to seek pre-travel health advice and stay longer at risk areas.[2, 16] They are also at increased risk of acquiring travel-related infections such as malaria and typhoid fever due to lack of compliance with preventive measures.[22, 23] Pre-travel health counseling and preventive interventions to immunocompromised VFR travelers are highly important given that they are at “double epidemiological risk” of travel-related infections because of their http://www.selleckchem.com/products/AC-220.html impaired immune status and behavioral and environmental risk related medroxyprogesterone to contact with the local population and adaptation of local habits. In this study, one in two travelers presented to the travel clinic within 4 weeks prior to departure. Obtaining pre-travel health advice 28 days or more prior to travel is recommended by the CDC to provide enough time for preventive measures to be effective at the start of travel.[15] An interval of 10 to 14 days is required for protective immune responses to develop in the majority of immunocompetent

travelers for the three travel-related vaccines administered in this study.[24-26] In addition, administration of certain malaria prophylaxis medications such as mefloquine and chloroquine should commence 1 to 2 weeks prior to travel for efficacy and tolerability.[15] Presenting in a timely manner for pre-travel health interventions is even more important for immunocompromised travelers. The immunocompromised host is less responsive to vaccinations and protective levels of vaccines may also be of shorter duration. Studies of SOT recipients and patients infected with HIV have shown lower serological response to hepatitis A, typhoid fever, and yellow fever vaccines.[27-30] Studies are lacking to evaluate the response to travel-related vaccines in immunocompromised cancer patients and SCT recipients and thus specific guidelines regarding travel-related vaccine administration to these groups of travelers are absent.

However, as the UCHCC comprises about 10% of all HIV-infected individuals in NC, it is probably representative of the HIV-infected population in NC. Moreover, six southeastern states (North Carolina, South Carolina, check details Mississippi, Alabama, Georgia and Louisiana) report demographically similar epidemics, supporting the generalizability of these results to the southeast USA [39–41]. The comparable rates of enrolment between Black and non-Black patients and between genders and those of different sexual orientations may partly be

attributed to the demographic make-up of the ID clinic and to the existing ACTG. Previous studies have shown that, compared with other ACTG sites, the UNC ACTG has high trial enrolment rates for racial/ethnic minorities,

and for women trial participation is associated with living in an area with an NIH- or CDC-supported research network [12,34]. In addition, NC has historically had strict eligibility criteria for the state-funded AIDS Drug Assistance Program (ADAP). Limited access to ADAP may leave participation in HIV treatment trials as the only option for access to ART. Finally, we recognize that several unmeasured variables, including work pressures, child-bearing wishes and vertical transmission Topoisomerase inhibitor issues, could have influenced our study results. In summary, in the clinical setting studied we achieved high rates of participation in HIV treatment trials. Gender did not appear to impact participation in HIV treatment trials but Black patients were slightly less likely to participate in these trials. We hypothesize that, in part, our results might be explained by guidelines and policies adopted both in the USA and in other countries to correct the imbalance Dynein in trial participation [15,42]. Considering the substantial proportion of HIV-infected patients who are Black, future

trials need to consider strategies to further incorporate underrepresented populations. Further investigation into the role of insurance in trial participation is needed. A continued exploration of barriers to clinical trial participation must consider other factors, including trust issues, awareness and information about clinical trials and trial characteristics. We thank Julius Atashili PhD for his assistance with editing this paper. We greatly appreciate the support of all the personnel involved in the conduct of the clinical trials and in the development and ongoing maintenance of the University of North Carolina (UNC) Center for AIDS Research (CFAR) HIV/AIDS clinical cohort, and that of the HIV care providers and staff of the UNC infectious diseases clinic. In particular, we thank the patients who participated in this study.

It is well known that amyloid beta (Aβ) oligomers cause synaptic dysfunction by inducing calcineurin-dependent AMPA

receptor (AMPAR) internalization. However, it is unknown whether Aβ-induced synaptic deficits depend upon tau phosphorylation. It is also unknown whether changes in tau can cause calcineurin-dependent loss of AMPARs in synapses. Here, we show that tau mislocalizes to dendritic spines in cultured MK 2206 hippocampal neurons from APPSwe Alzheimer’s disease (AD)-transgenic mice and in cultured rat hippocampal neurons treated with soluble Aβ oligomers. Interestingly, Aβ treatment also impairs synaptic function by decreasing the amplitude of miniature excitatory postsynaptic currents (mEPSCs). The above tau mislocalization and Aβ-induced synaptic impairment are both diminished by the expression of AP tau, indicating that these events require tau phosphorylation. The phosphatase activity of calcineurin is important for AMPAR internalization via dephosphorylation of GluA1

residue S845. Quizartinib price The effects of Aβ oligomers on mEPSCs are blocked by the calcineurin inhibitor FK506. Aβ-induced loss of AMPARs is diminished in neurons from knock-in mice expressing S845A mutant GluA1 AMPA glutamate receptor subunits. This finding suggests that changes in phosphorylation state at S845 are involved in this pathogenic cascade. Furthermore, FK506 rescues deficits in surface AMPAR clustering on dendritic spines in neurons cultured from transgenic mice expressing P301L tau proteins. Together, our results support the role of tau and calcineurin as two intermediate signaling molecules between Aβ initiation and eventual synaptic dysfunction early in AD pathogenesis.

“
“Task-based functional magnetic resonance imaging (fMRI) has been successfully employed to obtain somatotopic maps of the human PRKACG sensorimotor cortex. Here, we showed through direct comparison that a similar functional map can be obtained, independently of a task, by performing a connectivity-based parcellation of the sensorimotor cortex based on resting-state fMRI. Cortex corresponding to two adjacent Brodmann areas (BA 3 and BA 4) was selected as the sensorimotor area. Parcellation was obtained along a medial–lateral axis, which was confirmed to be somatotopic (corresponding roughly to an upper, middle and lower limb, respectively) by comparing it with maps obtained using motoric task-based fMRI in the same participants. Interestingly, the resting-state parcellation map demonstrated higher correspondence to the task-based divisions after individuals performed the motor task. Using the resting-state fMRI data, we also observed higher functional correlations between the centrally located hand region and the other two regions, than between the foot and tongue.

Consequently, Tn916 insertion in pCY186 may lead to the instability of this nonessential replicon in vitro, leading to the observed insertion frequencies. Analysis of the complete genome sequence from B. proteoclasticus B316T indicates that approximately 90.0% of the genome is made up of ORFs, but annotation

of the full sequence indicated click here that only (18 of 53, 34.0%) of the Tn916 insertion sites were in ORFs (Fig. 1, Table 1). The association of transposon integration within intergenic regions in the B316T genome may be inter-related with the analysis of the coding vs. noncoding regions: intergenic regions have an overall GC ratio of 34.7%, compared with 39.3% for the genome overall, and thus are comparatively more AT-rich. Similarly, the intergenic regions of H. influenzae Rd KW20 were 5% more AT-rich than the coding regions (Nelson et al., 1997). These data indicate that the integration of Tn916 in B316T is likely to be site-specific with hot spots for insertion, despite it having a relatively AT-rich/GC-poor genome. Identification of the

integration sites in the isolates generated from this study enabled the modelling of a consensus sequence for Tn916 integration in B316T (Fig. 2), which consisted of transposon target sites that were characteristically AT-rich, with a more variable 6-bp spacer sequence contained within the AT-rich target regions Regorafenib (Fig. 2). Comparison of the modelled B316T-derived consensus with those derived from the insertion sites of Tn916 transposon mutants in other bacterial strains indicates conservation of the core TTTTTnnnnnnAAAAA sequence across all mutants that were examined (Scott et al., 1994; Nelson et al., 1997). Modelled consensus

target sequences for Tn916 insertions in ORFs, intergenic regions and sites where more than five separate Tn916 insertions occurred were also determined, but no specific characteristics were observed that differentiated these modelled consensus sequences from those that represented all insertion sites (data not shown). However, when the modelled 16-bp consensus target sequence (Fig. 2), with up to two mismatches, was used to search the complete B316T genome, 39 theoretical insertion O-methylated flavonoid sites were identified, 19 of which were in coding regions, 20 of which were in noncoding regions and included nine where the insertion site had been identified from purified B316T tetracycline-resistant mutants (six noncoding: insertion numbers 13, 23, 28, 30, 32 and 48 and three coding: insertion numbers 21, 46 and 52, Table 2) during conjugation experiments. We were unable to categorically deduce whether any theoretical transposon insertion sites in any of the specific genes was lethal, but based on our assessments on the likely gene function of the mutated gene and the adjacent gene, four of the 16 theoretical Tn916 insertion sites were likely to be essential and could be lethal.