In E coli, our group and Kahramanoglou et al investigated a pot

In E. coli, our group and Kahramanoglou et al. investigated a potential role for Dcm in transcriptional regulation (Kahramanoglou et al., 2012; Militello et al., 2012). In summary, the two reports indicate that the loss of Dcm causes an increase in gene expression of several categories of genes, most notably ribosomal protein genes. These observations were important as they indicate that Dcm can influence

gene expression and that Dcm is normally repressive. In these studies, the effect of Dcm on gene expression was primarily restricted to stationary phase. Kahramanoglou et al. proposed that Dcm represses expression of the stationary phase sigma factor rpoS, and the loss of Dcm-mediated repression results in the up-regulation of rpoS and a downstream change in stationary phase gene expression Selleck PI3K inhibitor (Kahramanoglou et al., 2012). Yet, the relationship between 5-methylcytosine and gene expression is still relatively unexplored, and many questions remain. In particular, we are interested in phenotypes

associated with loss of Dcm. Dcm does not seem to have an effect on growth rate, the ability of cells to enter stationary phase, or the ability of cells to persist in stationary phase [K.T. Militello & R.D. Simon, unpublished data and (Kahramanoglou et al., 2012)]. We previously identified genes that have 5′CCWGG3′ recognition sites in the promoter region, and these targets are potentially regulated by cytosine DNA methylation (Militello et al., TAM Receptor inhibitor 2012). One identified target from this analysis was the sugE gene. The sugE gene has one Dcm site c. 10 nucleotides upstream from the transcription

start site and three in the gene body (Supporting Information, Fig. S1A). The E. coli sugE gene was originally identified as a suppressor of groEL (Greener et al., 1993). SugE is a membrane transporter with almost four predicted membrane spanning regions and is a member of the small multidrug resistance family (Bay et al., 2008). SugE RNA is expressed at stationary phase (Table 2) (Greener et al., 1993) and thus could potentially be regulated by Dcm. The function of the E. coli sugE gene is a bit of a mystery. In an initial study of E. coli drug transporters, SugE-mediated resistance to quaternary ammonium compounds (QACs) and ethidium bromide (ETBR) was not observed when sugE was overexpressed (Nishino & Yamaguchi, 2001). However, Chung and Saier reported that sugE overexpressing cells have increased resistance to several QACs (Chung & Saier, 2002), but not ETBR. Thus, the original model has been that the E. coli SugE protein generates resistance to a narrow range of QACs, but does not generate cells resistant to other compounds such as ETBR. However, not all subsequent data fit with this simple model, especially with respect to a lack of an effect of SugE on ETBR resistance. For example, overexpression of the Citrobacter freundii sugE homolog in E.

RNA was pelleted at 16 000 g for 20 min at 4 °C, washed once with

RNA was pelleted at 16 000 g for 20 min at 4 °C, washed once with 1 mL of 70% ethanol, repelleted and briefly air-dried before being resuspended in 100 μL of RNase-free water. The

resuspended RNA was then further purified using the Qiagen RNeasy Mini Kit (Qiagen) according to the manufacturer’s instructions. The pure RNA was stored at −80 °C. RNA was DNase treated using the Ambion turbo-free DNA kit according to the manufacturer’s instructions. cDNA was synthesized using the high-capacity cDNA reverse transcription kit (Applied Biosystems). A total of ∼1.2−1.5 μg of RNA was used in a 20-μL reaction in all cases. cDNA was synthesized using a PCR cycle of 25 °C for 10 min, Selleck Navitoclax 37 °C for 120 min and 85 °C for 5 s. qRT-PCR was performed using the custom-made Taqman gene expression assays (Applied Biosystems). A total of 60 ng of cDNA was used in each 20 μL reaction. Reactions were performed in 20 μL containing 10 μL 2 × Taqman gene expression Mastermix (Applied Biosystems),

1 μL Taqman gene expression assay (Applied Biosystems) and 9 μL cDNA (60 ng). The real-time PCR cycle was carried out in an ABI Prism 7000 Sequence Detection System (Applied Biosystems) (50 °C for 2 min, 95 °C for 10 min and then 40 cycles of 95 °C for 15 s, followed by 60 °C for 1 min). The fold change in the expression levels of each of the genes was calculated using the ΔΔCt method (Livak & Schmittgen, 2001). RNA was extracted from mid-log cultures of M. smegmatis as described above, and the 5′RACE system for the rapid amplification of cDNA ends find more (Version 2.0, Invitrogen) was used according to the manufacturer’s instructions, using the primers cpn60.1 gsp1, cpn60.1 gsp2 and cpn10 gsp2. cDNA was tailed at the 5′ ends using poly-cytosine and transcriptional start sites were identified by detection

of the junction of this poly-C tail in the sequenced cDNA. The promoterless lacZ E. coli–Mycobacterium shuttle vector pSD5B was used to analyse promoter activity (Jain et al., Oxalosuccinic acid 1997). Fragments of varying lengths upstream of the cpn60 or cpn10 genes were amplified with primers containing XbaI and SphI sites, or XbaI sites alone. The products were digested as appropriate and ligated into plasmid pSD5B. The resultant recombinant plasmids contained the various promoter regions just upstream of the lacZ gene (Table 1 and Fig. 1). Each of the pSD5B constructs containing a promoter region was electroporated into M. smegmatis mc2155 cells. The strains were grown in liquid media at 37 °C for 2 days, after which their absorbance at OD600 nm was measured. Each culture (100 μL) was added to 900 μL Z buffer (30 °C). A drop each of 0.1% sodium dodecyl sulphate and chloroform was then added to the tubes, which were vortexed to lyse the cells. The reaction was started by adding 200 μL ONPG (4 mg mL−1) and mixing well. When a significant yellow colour developed, the reaction was stopped by addition of 500 μL 0.

, 2006; Wen et al, 2006, 2010a, b) Previously, we reported that

, 2006; Wen et al., 2006, 2010a, b). Previously, we reported that deficiency of BrpA (for biofilm regulatory protein A) in S. mutans caused major defects in the ability of the deficient mutants to tolerate acid and oxidative stresses and the ability to accumulate biofilms (Wen & Burne, 2002; Wen et al., 2006). The rex gene was found to be significantly decreased in the BrpA-deficient mutant, TW14D, during the early-exponential phase of growth (data not

shown), suggesting that rex expression is influenced by BrpA and that rex may be involved in the regulation of stress tolerance response and/or biofilm formation by S. mutans. To verify that rex is indeed a part of the BrpA-regulon, the expression of rex was analyzed using RealTime-PCR with total RNAs extracted from cultures grown in BHI and harvested during early (OD600 nm≅0.2), mid (OD600 nm≅0.4), and late (OD600 nm≅0.6) exponential PI3K inhibitor phase, respectively. The expression of rex in the wild-type strain was at its highest level during early-exponential phase, averaging 7.85E+07 copies μg−1 of total RNA, although the underlying mechanism governing the regulation remains unclear. Consistent with microarray data, rex expression in TW14D was decreased by more than sixfold during this period of growth, with an average of only 1.00E+07 copies μg−1 of total RNA

(P<0.001). However, no significant differences were observed in cells from mid- or late-exponential phase cultures (data not shown). To investigate whether Rex could be associated with phenotypes observed in BrpA-deficient mutants, an internal SB431542 purchase fragment (nucleotides 136–584 relative to the translational initiation site) of the rex gene was deleted and replaced with

a nonpolar kanamycin resistance element (Zeng et al., 2006). Rex-deficiency did not have a major impact on the morphology and growth rate in planktonic cultures in BHI (Fig. 1a). However, when biofilm formation in 96-well culture plates was analyzed (Loo et al., 2000; Wen & Burne, 2002), the Rex-deficient mutant, TW239, was shown to accumulate only a small fraction of the biofilms of the wild-type, UA159. Following staining with 0.1% crystal violet after 24 h, the OD575 nm of mutant biofilms was 3.5-fold (P<0.001) less than that of the wild-type strain when Adenosine triphosphate grown on glucose (Fig. 1b) and decreased by more than threefold (P<0.001) when sucrose was the carbohydrate source (Abstract, 87th IADR Annual Conference #2652). When grown on glass slides in BMGS (Nguyen et al., 2002; Wen et al., 2010a, b), the biofilms formed by TW239 after 3 days were about 6.2-fold less abundant than those formed by UA159, with an average of 1.82E7(±1.02E7) CFU for TW239 vs. 1.13E8(±2.88E7) (P<0.001) for UA159. Similar results were also observed with biofilms grown on hydroxylapatite discs, a commonly used in vitro tooth model. As compared with the wild-type, biofilms of the Rex-deficient mutant also had an altered structure.

Conventional methods for manipulating neural activity, such as el

Conventional methods for manipulating neural activity, such as electrical microstimulation or pharmacological blockade, have poor spatial and/or temporal resolution. Algal protein channelrhodopsin-2 (ChR2) enables millisecond-precision control of neural

activity. However, a photostimulation method for high spatial resolution mapping in vivo is yet to be established. Here, we report a novel optical/electrical probe, consisting of optical fiber bundles and metal electrodes. Optical fiber bundles were used as a brain-insertable endoscope for image transfer and stimulating light SRT1720 mouse delivery. Light-induced activity from ChR2-expressing neurons was detected with electrodes bundled to the endoscope, enabling verification of light-evoked action potentials. Photostimulation through optical fiber bundles of transgenic mice expressing ChR2 in layer 5 cortical neurons resulted in single-whisker movement, indicating spatially restricted activation of neurons in vivo. The probe system described here and a combination of various photoactive molecules will facilitate studies on the causal link between specific neural activity patterns and behavior. A fundamental problem in neuroscience is how spatially and temporally complex patterns of neural activity mediate higher brain functions, such as specific actions Cabozantinib and perceptions. To answer this question, not only recording, but also controlling neural activity with high

spatio-temporal resolution is required. Electrical stimulation has long been used to investigate neural substrates for a number of motor and cognitive functions (Fritsch & Hitzig, 1870; Penfield & Boldrey, 1937; Asanuma et al., Methocarbamol 1968; Salzman et al., 1990).

However, this method has some shortcomings – the inability to selectively target neuronal subtypes, limited spatial resolution with extracellular stimulation, and the limited number of neurons (typically one cell) that can be activated with intracellular stimulation. Recently, light-sensitive cation channels such as algal protein channelrhodopsin-2 (ChR2) have been adopted to stimulate neurons by light. This method offers many advantages over conventional methods for controlling neural activity, such as millisecond-precision, lack of toxicity and genetic control of target cell types (Boyden et al., 2005; Ishizuka et al., 2006). Combination of cell type-specific expression of ChR2 and photostimulation revealed particular roles of various types of neurons (Adamantidis et al., 2007; Cardin et al., 2009; Tsai et al., 2009). Light-induced silencing of neural activity is also possible using a light-driven chloride pump, such as halorhodopsin (Han & Boyden, 2007; Zhang et al., 2007). However, controlling neural activity in living animals by light with high spatial resolution is yet to be achieved. To apply this photic control method of neural activity in vivo, a combined probe consisted of optical fiber and electrode is implanted in the brain to stimulate and record neural activity.

16S rRNA gene transcript numbers of total Bacteria, and selected

16S rRNA gene transcript numbers of total Bacteria, and selected bacterial taxa (Clostridia [Group I], Planctomycetaceae, and two uncultivated taxa of Bacteroidetes) decreased more in anoxic than in oxic cellulose-supplemented soil microcosms in the presence of both herbicides. Collectively, the results suggested that the metabolism of anaerobic cellulose-degrading Bacteria was impaired by typical in situ herbicide concentrations, whereas in situ concentrations did not impair metabolism of aerobic cellulose- and cellobiose-degrading soil Bacteria. Cellulose is metabolized by diverse aerobic

and anaerobic, cellulolytic and saccharolytic microorganisms in soils (Falkowski et al., 2002; Lynd PS-341 et al., 2002; Wei et al., 2009; Schellenberger et al., 2010). Increasing Bleomycin application of herbicides over the past decades in agriculture has resulted in accumulation of herbicide residues in soils that may affect microbial metabolism (Wainwright, 1978; Thorstensen et al., 2001; Chowdhury et al., 2008; Hiller et al., 2008). Herbicides can be degraded in soils (Müller et al., 2001; Gonzales et al., 2006), although, their degradation is slow compared with that of natural organic compounds (such as sugars or amino acids) and is primarily aerobic (Harrison et al., 1998; Knauber et al., 2000; Liu et al., 2010). Bentazon [3-isopropyl-1H2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide; pKa = 3.28]

is a control agent of broadleaf weeds in agricultural crop plantations. It inhibits the photosynthetic electron flow in plants, and interacts with membranous proteins, which leads to an inhibition of ATPase (Hull & Cobb, 1998). Therefore, bentazon inhibits growth of pure cultures of various soil bacteria (e.g. Actinobacteria, rhizobia, cyanobacteria), and reduces dinitrogen

fixation and nitrogen mineralization in soils (Cernakova et al., 1991; Galhano et al., 2009). MCPA (4-chloro-2-methylphenoxyacetic Histone demethylase acid; pKa = 3.73) is also used as a control agent of broadleaf weeds, and acts as a plant growth hormone analog. MCPA enters the cytoplasm in the acidic form by diffusion, which causes a dissipation of the transmembrane proton-motive force (Cabral et al., 2003). The toxic effect of MCPA on cell growth has been observed with pure cultures of yeast, Pseudomonas putida and Vibrio fischeri (Ahtiainen et al., 2003; Cabral et al., 2003). Therefore, the toxic effects of these herbicides on cellulose-degrading soil Bacteria have been addressed in the current study. Soil from a wheat-planted agricultural cropland (Germany; 48°30.0′N, 11°20.7′E; sampled June 2009) was used (Table 1) to prepare soil microcosms. Cellulose- and cellobiose-supplemented soil microcosms were incubated at 15 °C in darkness. Two different experiments were set up. Microcosms with wet soil were supplemented with cellulose paper sheets.

Screening for both inherited and modifiable risk factors and main

Screening for both inherited and modifiable risk factors and maintaining vigilance regarding potential drug–drug interactions, not only with ART but also with therapies administered concomitantly for risk factor modification, are also of increasing importance. Knowledge of the extent to which HIV infection affects the normal ageing process and the risk of developing identified age-related comorbidities is expanding slowly. More insight is needed this website into how each comorbidity is affected by HIV infection itself and by ART, and how this interplay eventually impacts overall morbidity

and mortality in a given individual. It is important to note that management of comorbidities is a

much more challenging issue in developing countries because of the greater burden of HIV infection in terms of overall prevalence, environmental conditions and variations in drug treatments. In this paper we focus solely on the challenge of managing HIV comorbidities in developed countries. The increase in life expectancy achieved through the introduction of more effective ART means that Target Selective Inhibitor Library HIV-infected patients are now more likely to experience the age-related diseases that affect the general population. However, the prevalence of these diseases is higher and their onset is earlier in HIV-infected patients, probably as a result of the complex interrelationship among HIV infection, coinfection and ART [1,4]. Although a number of common comorbidities affect HIV-infected patients, this article focuses on liver disease (particularly in the context of HBV or HCV coinfection), CVD, kidney disease and osteoporosis. The following is an overview of each of the comorbidities tuclazepam discussed in this article. The second section of the article discusses the management of these comorbidities in greater detail. Liver disease is

the most frequent cause of non-AIDS-related death in HIV-infected individuals [3]. Risk factors include viral hepatitis, alcohol consumption, obesity, hyperlipidaemia, the administration of hepatotoxic drugs, insulin resistance and diabetes [5]. The major factor influencing disease development and progression is coinfection with HCV, which increases the risk of both cirrhosis and liver decompensation [6]. Approximately one-third of HIV-infected individuals in Europe are coinfected with HCV, and the rate of HCV coinfection is even higher (>50%) in those subpopulations involved in substance abuse or diagnosed with psychiatric illness [7]. Coinfection with HBV also increases liver-related mortality in HIV-infected individuals, although its overall prevalence in Europe is much lower at only 6%. The relationship between HIV and HBV is also complex.

95, P = 87 × 10−40 and r = 076, P = 13 × 10−15 for SCN-intact

95, P = 8.7 × 10−40 and r = 0.76, P = 1.3 × 10−15 for SCN-intact and SCN-lesioned rats, respectively). The damping rate of circadian Per2-dLuc rhythm was calculated as follows: a difference between the onsets of first and fourth peak was divided by the amplitude of first peak. Repeated-measure anova with a post hoc Fisher’s Protected Least Significant Difference (PLSD) test (Excel Statistics) was used to statistically evaluate differences in the 24-h behavior profile

between pre-R and R-MAP or R-Water, and changes in the amounts of water and food intake and body weight. Unpaired t-tests were used to evaluate differences in the phases of behavioral rhythm between two groups. Two-factor factorial anova with a post selleck chemicals llc hoc Fisher’s PLSD test was used to evaluate check details differences

in the circadian peak phase, amplitude and damping rate of Per2-dLuc rhythms between the SCN-intact and SCN-lesioned rats, and between R-MAP and R-Water groups. Twenty-four-hour profiles of spontaneous movement and wheel-running activity were substantially modified by R-MAP in SCN-intact rats (Figs 1 and 3). The behavioral activities during the restricted time of MAP supply were enhanced and the nocturnal activities were suppressed in some rats but this was not statistically significant in the group (Fig. 3). Under subsequent ad-MAP, the activity

components at the restricted time of MAP supply showed rapid phase-delay shifts for the following 5 days, but the phase shifts slowed down when the activity onsets passed the middle of the dark phase. On the other hand, behavioral activity was enhanced by R-Water immediately prior to daily water supply (Fig. 3). Under subsequent ad-MAP, the nocturnal activities were enhanced and slightly phase-delayed. Circadian behavioral rhythms were abolished by bilateral SCN-lesion (Fig. 2). In the 4-Aminobutyrate aminotransferase R-MAP group, the behavioral activities were significantly enhanced during the restricted time of MAP supply, but such enhancement was not observed in the R-Water group (Fig. 3). Small but significant pre-drinking activity bouts were detected on the last few days of R-MAP and R-Water (Figs 2 and 3). Under subsequent ad-MAP, the enhanced activities during the restricted time of MAP supply showed steady phase-delay shifts without interruption by LD, indicating free-running of MAO. On the other hand, ad-MAP enhanced and consolidated behavioral activities in the R-Water group immediately after the previous restricted time of water supply, to form behavioral rhythms with a period close to 24 h. The phases of behavioral rhythms on the first day of ad-MAP were analysed in terms of activity band (Fig. 4A).

Changes in the phosphorylation level of these regulators can alte

Changes in the phosphorylation level of these regulators can alter the expression of operons encoding PTS transporters and PRD protein-regulated genes carrying out diverse cellular

functions of the bacteria (Deutscher et al., 2006). The FrzR activator could act similarly by being involved in the regulation of both the frz and the yicJI operons. Although the yicJI operon is not essential for the life of E. coli, our results indicate see more that it is necessary for its fitness under all the tested growth conditions. The molecular mechanisms by which the YicJ and YicI proteins are involved in the fitness of the bacteria and particularly in its capacity to survive during the late stationary phase of growth are actually

unknown. However, some metabolic enzymes were described to also play a regulatory role by binding to DNA and RNA, by being involved in mRNA degradation, or by sequestering transcriptional regulators (Morita et al., 2004; Loughman & Caparon, 2006; Domain et al., 2007; Commichau & Stülke, 2008; Commichau et al., 2009). Similarly, the YicI glycosidase, which is devoid of predicted nucleic acid-binding sites, might be involved both in the metabolism of oligosaccharides containing α-1,6-xylosidic linkage and in the interaction with protein(s) involved in the fitness of the bacteria during the late stationary phase of growth. This model is Galunisertib order now being tested in our laboratory. This work was supported by the Era-NET PathoGenoMics European program

(grant ANR-06-PATHO-002-01) and by the Institut Fédératif de Recherche 136 ‘Agents transmissibles et Infectiologie’ (France). G.R. was supported by a grant of the Fondation de la Recherche Médicale (Fin de thèse – scientifique). “
“The percentage of bacterial infections refractory to standard antibiotic treatments very is steadily increasing. Among the most problematic hospital and community-acquired pathogens are methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PA). One novel strategy proposed for treating infections of multidrug-resistant bacteria is the activation of latent toxins of toxin–antitoxin (TA) protein complexes residing within bacteria; however, the prevalence and identity of TA systems in clinical isolates of MRSA and PA has not been defined. We isolated DNA from 78 MRSA and 42 PA clinical isolates and used PCR to probe for the presence of various TA loci. Our results showed that the genes for homologs of the mazEF TA system in MRSA and the relBE and higBA TA systems in PA were present in 100% of the respective strains. Additionally, reverse transcriptase PCR analysis revealed that these transcripts are produced in the clinical isolates.

It has the ability to interact with and invade host cells, and th

It has the ability to interact with and invade host cells, and then to live within these cells (Ly & Casanova, 2007). We report that the two Lactobacillus strains display killing activity against G. vaginalis, UPEC and S. typhimurium by substances present in the cell-free culture supernatants (CFCSs). Moreover, our results show that the main metabolic product of Lactobacillus, lactic acid, displays

no killing activity at the concentration present in Lactobacillus cultures, whereas hydrogen peroxide dose-dependently killed these pathogens. We also provide evidence that at the concentration present in Lactobacillus cultures, lactic acid considerably enhances the killing activity of hydrogen peroxide. The prototype UPEC strain CFT073 (Mobley et al., 1990) and S. typhimurium SL1344 Pirfenidone (Finlay & Falkow, 1990) were used. Bacteria were Inhibitor Library cultured in Luria–Bertani (LB) agar (Difco Laboratories, Detroit, MI) and incubated at 37 °C for 24 h. Gardnerella vaginalis DSM 4944 was grown on Gardnerella agar plates purchased from BioMerieux (Lyon, France), as described previously (Atassi et al., 2006a, b). Bacteria were suspended in pH 7.0 buffered sodium chloride-peptone solution at about 106 CFU mL−1. Five hundred microliters of the prepared suspension was spread on the agar plate. The inoculated plates were dried under a sterile laminar airflow. The agar plates were then

incubated under anaerobic conditions in a sealed anaerobic jar (Becton Dickinson) at 37 °C for up to 36 h. Before being used, G. vaginalis was subcultured in brain–heart infusion supplemented with yeast

extract (1%), maltose (0.1%), glucose (0.1%) and horse serum (10%) under anaerobic conditions in a sealed anaerobic jar at 37 °C for up to 36 h. For each experiment, bacteria were subcultured for the exponential phase in appropriate media. Lactobacillus johnsonii strain NCC533 was from the Nestec Research Center Niclosamide at Vers-chez-les-Blanc (Switzerland). The L. gasseri KS120.1 strain isolated from the vaginal flora of a healthy woman (Department of Obstetrics and Gynecology, Zurich University Hospital, Switzerland) was from Medinova (Zurich, Switzerland) (Atassi et al., 2006a, b). All the Lactobacillus strains were grown in De Man, Rogosa, Sharpe (MRS) broth (Biokar Diagnostic, Beauvais, France) for 24 h at 37 °C. The Lactobacillus culture was adjusted to pH 4.5 by adding HCl or NaOH to ensure standardized conditions. Cultures of the Lactobacillus strains (24 h) were centrifuged at 10 000 g for 30 min at 4 °C. Bacteria were collected and washed three times with sterile phosphate-buffered saline (Coconnier et al., 1997, 2000). Supernatants of the centrifuged cultures were collected and passed through a sterile 0.22-μm filter unit Millex GS (Millipore, Molsheim, France).

The freshwater cyanophage AS-1 is a myovirus capable of infecting

The freshwater cyanophage AS-1 is a myovirus capable of infecting

Synechococcus sp. strain PCC6301 (formerly Anacystis nidulans) and Synechococcus cedrorum (Safferman et al., 1972). Early studies showed that light influenced the adsorption of AS-1 to Synechococcus sp. PCC6301, with only 40% of the phage adsorbed to the cells in the dark, compared with 80% in the light (Cseke & Farkas, 1979). However, a 10-fold increase in the Na+ concentration in the medium counteracted the effect of darkness and restored the adsorption of AS-1 to the level obtained in the light (Cseke & Farkas, 1979). This observation has been explained as being due to light-induced charge neutralization selleck at the cell surface or by light-induced

changes in the ionic composition at the cell surface (Cseke & Farkas, 1979). Light was found to strongly influence the infection of Synechococcus elongatus sp. PCC7942 GSK126 by AS-1, with phage progeny production being correlated with a diel pattern under natural light (Kao et al., 2005). One effect of the light was at the level of adsorption. In this paper, the influence of light on adsorption was investigated using a model system consisting of the ‘photosynthetic’ cyanophage S-PM2 and its host the marine cyanobacterium Synechococcus sp. WH7803. Synechococcus sp. WH7803 and BL161 were grown in an artificial seawater (ASW) medium as described previously (Wilson et al., 1996). The cyanophages used in this study are listed in Table 1 and were propagated as described by Wilson et al. (1993). Phage titration was based on a previously reported protocol, with minor modifications (Wilson et al., 1996). Briefly, cyanophage samples were serially over 10-fold diluted in ASW, and

samples were left to adsorb to 100-fold concentrated exponentially growing (OD750 nm of 0.35–0.40) Synechococcus sp. WH7803 cells for 1.5 h at 25 °C with gentle occasional shaking. The agar used in this study was cleaned using water, ethanol and acetone according to a well-established method (Waterbury & Willey, 1988). These phage–cell suspensions were then evenly mixed with 3 mL 0.3% w/v molten ASW agar and poured as top layers onto 1% w/v ASW agar plates before being kept on the bench at room temperature for at least 2 h. These plates were incubated in a Sanyo Environmental Test Chamber (model: MLR-351H) at 25 °C with illumination at 15–25 μE m−2 s−1. Plaques, which normally appeared within 7 days, were counted manually. Control plates received ASW with no cyanophage. To determine the kinetics of adsorption under light and dark conditions, cyanophage S-PM2 was added to two identical samples of cells from cultures of Synechococcus sp. WH7803 (OD750 nm of 0.35–0.40) at a multiplicity of infection (MOI) of 0.02. The MOI was determined by dividing the number of phages added by the number of bacteria added.