Assessment of a Community-Based Nutrition Program for Women and Children in Nepal Using Demographic and Health Survey.

Undernutrition is a particularly acute problem in middle- and low-income countries. The "Suaahara" program is a 5-year community-focused program in Nepal, aimed at improving the health and nutrition of pregnant and lactating women and their children under the age of 2 years. This research contributes to evidence on the impact of the "Suaahara" program in 41 treated districts compared to 34 control districts. Using the difference-in-differences method, we found that the weight-for-height z-score and body mass index z-score of children under the age of 2 in the treated districts significantly increased by 0.223 standard deviations (SDs) and 0.236 SDs, respectively, compared with the control districts 5 years before and after the program. The number of antenatal care visits (at least four visits) and safe deliveries significantly increased for pregnant women by 10.4% and 9.1%, respectively, in the treated districts compared with the control districts. The prevalence of fever in children under 2 years of age was significantly reduced by 6.2% in the treated districts. The results show the significance of a policy evaluation with transparent indicators on public health, which is necessary for policymakers so that they can propose evidence-based policy.

'Who will I become?': possible selves and depression symptoms in adolescents.

BACKGROUND: Adolescence is an important period for the development of the possible self. It is also a time when depression is prevalent. The cognitive theory of depression proposes that a negative view of the future is a key feature of depression. Targeting these negative thoughts about the future during cognitive behavioural therapy may be helpful in depression. However, little is known about how adolescents envisage their future (i.e. possible) self, or if the content is associated with affect. The aim of this quantitative study is to describe how adolescents describe their 'possible self' and examine the relationship between the valence of the possible self and depression in adolescents. METHOD: Adolescents (n = 584) aged 13-18 years were recruited via opportunity sampling via their schools and completed measures of depression symptoms (the Mood and Feelings Questionnaire) and the 'possible self' (a variant of the 'I Will Be' task). Possible selves were coded for content and valence. RESULTS: Despite depression severity, the most common possible selves generated by adolescents were positive and described interpersonal roles. The valence of the possible self was associated with depression severity but only accounted for 3.4% of the variance in severity. CONCLUSION: The results support the cognitive model of depression. However, adolescents with elevated symptoms of depression were able to generate positive, possible selves and therefore may remain somewhat 'hopeful' about their future despite clinically significant depression symptoms. Future-oriented treatment approaches such as cognitive behavioural therapy that focus on changing unhelpful negative future thinking may not be appropriate for this population.

Sequence and functional analysis of MIR319 promoter homologs from Brassica juncea reveals regulatory diversification and altered expression under stress.

KEY MESSAGE: Extensive regulatory divergence during development, abiotic stress and ABA regime observed amongst promoter homologs and homeologs of MIR319 from Brassica juncea. Gene duplication followed by sub-functionalization, neo-functionalization, and pseudogenization are routes to functional and adaptive diversification. The influence of polyploidy on protein-coding genes is well investigated but little is known about their impact on transcriptional regulation of MIRNA gene family. The present study was therefore performed with an aim to uncover regulatory diversification of MIR319 homologs and homeologs in Brassica juncea. We employed comparative genomics to identify and isolate six promoter homologs of MIR319 from B. juncea. Regulatory diversification was studied using analysis of reporter activity driven by BjMIR319 promoters in a heterologous system employing promoter-reporter fusion constructs. MIR319 is known to play important roles in leaf and flower development, and multiple stress responses. Reporter activity was therefore monitored during development, hormonal and stress regimes. In-silico analyses revealed differential distribution of cis-regulatory motifs and functional analysis revealed distinct spatiotemporal expression patterns. The significance of presence of selected cis-regulatory motifs corresponding to heat, cold, salt and ABA stress were further functionally validated. It was observed that promoter of Bj -MIR319a-A01 was upregulated in response to cold and salt stress, while promoter of Bj -MIR319c-A04 (D1) and Bj -MIR319c-A05 (FL) were downregulated in response to high temperature. In summary, comparative analysis of homologous promoters from Brassica juncea, an allopolyploid revealed extensive sequence and functional diversity. Spatiotemporal activity of reporter gene driven by BjMIR319 promoter was distinct, and partially overlapping with from those reported previously for A. thaliana. The present study clearly demonstrates regulatory divergence amongst promoter homologs of MIR319 in Brassica juncea during development and stress response, and underlines the urgent need for dissection of promoter function and detailed characterization including identification of interacting trans-factors. Genbank accession numbers: MT379853-MT379858.

Computer-delivered brief alcohol intervention for patients with liver disease: a randomized controlled trial.

BACKGROUND AND AIMS: Reducing alcohol consumption by liver disease patients can reduce morbidity and mortality. This study compared a computer-delivered brief alcohol intervention (cBAI) with standard care in a sample of US military veterans with liver disease. DESIGN: Multi-site, randomized controlled trial of a cBAI plus standard care (n = 67) versus standard care only (n = 71). Participants were assessed at baseline and 3- and 6-month follow-up. SETTING: US Veterans Health Administration liver clinics. PARTICIPANTS: Participants were mostly male and diagnosed with hepatitis C. INTERVENTIONS AND COMPARATORS: A cBAI tailored to veterans with liver disease and consisting of assessment and personalized feedback. Standard care was brief education and advice about alcohol and liver disease. MEASUREMENT: Primary outcomes were self-reported number of drinking days and unhealthy drinking days (defined as more than two drinks for men and more than one for women) in the past 30 days at 6-month follow-up. Secondary outcomes were these two variables at 3-month follow-up, and drinks consumed per drinking day, depression and overall health at 3- and 6-month follow-ups. Missing data were imputed using multiple imputation. FINDINGS: Compared with standard care, cBAI participants reported significantly fewer drinking days at 6-month follow-up and fewer unhealthy drinking days at both 3- and 6-month follow-ups. Least square means (LS-means) for number of drinking days were 3.78 for the cBAI condition and 6.89 for the standard care condition at 6 months [LS-mean ratio = 3.78/6.89 = 0.55, 95% confidence interval (CI) = 0.34, 0.89]. LS-means for number of unhealthy drinking days were 1.04 for the cBAI condition and 2.57 for the standard care condition at 3-month follow-up (LS-mean ratio = 1.04/2.57 = 0.41, 95% CI = 0.19, 0.85). At 6-months follow-up, LS-means were 1.18 for the cBAI condition and 2.75 for the standard care condition (LS-mean ratio = 1.18/2.75 = 0.43, 95% CI = 0.20, 0.91). CONCLUSIONS: A computer-delivered brief alcohol intervention reduced drinking days and unhealthy drinking days at 6-month follow up in military veterans with liver disease compared with brief education and advice to reduce consumption.

Microsynteny analysis to understand evolution and impact of polyploidization on MIR319 family within Brassicaceae.

The availability of a large number of whole-genome sequences allows comparative genomic analysis to reveal and understand evolution of regulatory regions and elements. The role played by events such as whole-genome and segmental duplications followed by genome fractionation in shaping genomic landscape and in expansion of gene families is crucial toward developing insights into evolutionary trends and consequences such as sequence and functional diversification. Members of Brassicaceae are known to have experienced several rounds of whole-genome duplication (WGD) that have been termed as paleopolyploidy, mesopolyploidy, and neopolyploidy. Such repeated events led to the creation and expansion of a large number of gene families. MIR319 is reported to be one of the most ancient and conserved plant MIRNA families and plays a role in growth and development including leaf development, seedling development, and embryo patterning. We have previously reported functional diversification of members of miR319 in Brassica oleracea affecting leaf architecture; however, the evolutionary history of the MIR319 gene family across Brassicaceae remains unknown and requires investigation. We therefore identified homologous and homeologous segments of ca. 100 kb, with or without MIR319, performed comparative synteny analysis and genome fractionation studies. We detected variable rates of gene retention across members of Brassicaceae when genomic blocks of MIR319a, MIR319b, and MIR319c were compared either between themselves or against Arabidopsis thaliana genome which was taken as the base genome. The highest levels of shared genes were found between A. thaliana and Capsella rubella in both MIR319b- and MIR319c-containing genomic segments, and with the closest species of A. thaliana, A. lyrata, only in MIR319a-containing segment. Synteny analysis across 12 genomes (with 30 sub-genomes) revealed MIR319c to be the most conserved MIRNA loci (present in 27 genomes/sub-genomes) followed by MIR319a (present in 23 genomes/sub-genomes); MIR319b was found to be frequently lost (present in 20 genomes/sub-genomes) and thus is under least selection pressure for retention. Genome fractionation revealed extensive and differential loss of MIRNA homeologous loci and flanking genes from various sub-genomes of Brassica species that is in accordance with their older history of polyploidy when compared to Camelina sativa, a recent neopolyploid, where the effect of genome fractionation was least. Finally, estimation of phylogenetic relationship using precursor sequences of MIR319 reveals MIR319a and MIR319b form sister clades, with MIR319c forming a separate clade. An intra-species synteny analysis between MIR319a-, MIR319b-, and MIR319c-containing genomic segments suggests segmental duplications at the base of Brassicaceae to be responsible for the origin of MIR319a and MIR319b.

Peroxisome Proliferator-Activated Receptor γ Is Essential for the Resolution of Staphylococcus aureus Skin Infections.

Skin/soft tissue infections (SSTIs) caused by methicillin-resistant Staphylococcus aureus (MRSA) represent serious healthcare burdens worldwide. The host initially controls these infections with a pro-inflammatory infiltrate. However, once established, MRSA viability remains constant. To clear established MRSA SSTIs, the host must transition into the post-inflammatory resolution phase marked by infiltration of alternatively activated macrophages. Here we show that the host nuclear receptor, peroxisome proliferation activator receptor γ (PPARγ), is essential for this transition and MRSA clearance. Chemical PPARγ inhibition or genetic ablation of PPARγ in myeloid cells results in an extended inflammatory phase and exacerbated MRSA SSTIs. Conversely, treating mice with PPARγ agonists hastens the onset of the resolution phase and improves MRSA clearance in a myeloid-dependent fashion. The resolving fibrotic abscess lacks abundant glucose and oxygen but is replete with antimicrobial peptides, which together contribute to MRSA clearance. Thus, PPARγ agonists may serve as viable treatment options for complicated MRSA SSTIs.

An improved method for rapid analysis of promoters using modified sonication-assisted transient assay.

We present here a modified, sonication-assisted transient transformation assay for rapid analysis of cis-regulatory elements. We tested promoter elements from MIR159B locus of Brassica juncea by generating stable transgenic lines and compared the transcriptional activity of GUS reporter with that of the transient assay method. To obtain reliable and repeatable results, and to omit false-positive data, we optimized several parameters including sonication duration and cycle and concentration of Agrobacterium tumefaciens measured as optical density (O.D.) at 600 nm. To the best of our knowledge, this is the first report of promoter characterization of MIR159B from Brassica juncea, and comparative analysis of stable and transient lines. Our analysis shows that the protocol described herein allows understanding promoter activity/transcriptional control in tissues other than leaf or protoplast which have remained the mainstay for transient analysis thus far. We tested reporter gene GUS under the control of constitutive promoter, CaMV 35S, and MIR159b from Brassica juncea. We optimized the duration of sonication (5-, 10- and 15-min cycle), bacterial density (measured as O.D at 600 nm = 0.6/0.8/1.0) and Agro-infection time (5, 10, 15 min), and co-cultivation (12-, and 24-h). Sonication cycle of 10-min, followed by Agro-infection and co-cultivation with Agrobacterium tumefaciens with O.D. 600 nm = 0.8 and for 12 h was found to be optimum. We could successfully express reporter genes in deep-seated tissues such as floral organs and pollen grains where it was previously not possible to perform transient assay. Constitutive GUS activity was observed when reporter was placed under control of the constitutive promoter of CaMV 35S. Reporter GUS when placed under transcriptional control of MIR159b promoter from Brassica juncea showed reporter activity in floral tissues, in mature pollen grains. Comparative analysis of reporter activity from stable transgenic lines at T2 generation with that of transient assay system reveals identical to near-identical reporter activity. Transient assay could be successfully performed in tissues collected not only from Arabidopsis thaliana, but also from Brassica juncea and Brassica nigra to demonstrate its wide applicability. Our modified method thus has the potential of quick and rapid analysis of promoter activity and allows us to record the developmental dynamics and spatio-temporal expression pattern driven by specific promoters. Suitable modification and controls should also allow analysis of hormonal regulation and identification of trans-factors via DNA-protein interactions. Furthermore, this method can also be extended to study promoters under various environmental conditions that otherwise do not allow growth and complete life cycle of healthy plants and can be modified to test reporter activity in other non-model plants or plants with long life cycle.

Adapting a computer-delivered brief alcohol intervention for veterans with Hepatitis C.

OBJECTIVE: This study adapted an existing computer-delivered brief alcohol intervention (cBAI) for use in Veterans with the hepatitis C virus (HCV) and examined its acceptability and feasibility in this patient population. METHODS: A four-stage model consisting of initial pilot testing, qualitative interviews with key stakeholders, development of a beta version of the cBAI, and usability testing was used to achieve the study objectives. RESULTS: In-depth interviews gathered feedback for modifying the cBAI, including adding HCV-related content such as the health effects of alcohol on liver functioning, immune system functioning, and management of HCV, a preference for concepts to be displayed through "newer looking" graphics, and limiting the use of text to convey key concepts. Results from usability testing indicated that the modified cBAI was acceptable and feasible for use in this patient population. CONCLUSIONS: The development model used in this study is effective for gathering actionable feedback that can inform the development of a cBAI and can result in the development of an acceptable and feasible intervention for use in this population. Findings also have implications for developing computer-delivered interventions targeting behavior change more broadly.

Examining Postsecondary Education Predictors and Participation for Students With Learning Disabilities.

Given the history of poor postschool outcomes for students with disabilities, researchers repeatedly sought to demonstrate the links between predictor variables and postschool outcomes for students with disabilities. This secondary data analysis used the National Longitudinal Transition Study-2 to examine the relationship between postsecondary education-related transition services and postsecondary education participation for students with learning disabilities. Logistic regression analyses indicated receiving core content area instruction in the general education classroom was positively related to postsecondary education participation. Frequency distributions indicated students with learning disabilities attended 2-year college at higher rates than other postsecondary education programs. The results suggest educators should consider inclusion in general education classroom for core content area instruction for students with learning disabilities with postsecondary education goals to the extent permitted by their least restrictive environment.

Does Curriculum Matter for Secondary Students with Autism Spectrum Disorders: Analyzing the NLTS2.

A common presumption of secondary education is that what occurs in-school impacts students after they exit school. Previous researchers found transition-services received in school by students with autism spectrum disorder predicted their post-school success with regards to employment and independent living. This secondary analysis of the National Longitudinal Transition Study-2 sought to understand the relationship between curriculum--functional versus non-functional--and seven measures of post-school outcomes for students with autism spectrum disorder. The main results of the study include low rates of receipt of a functional curriculum, poor post-school outcomes, and the lack of relationship between curriculum and post-school outcomes for students with autism spectrum disorder.

Functional modularity of the arginine catabolic mobile element contributes to the success of USA300 methicillin-resistant Staphylococcus aureus.

The USA300 community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) lineage causes the majority of skin and soft tissue infections (SSTIs) and is highly associated with the carriage of the arginine catabolic mobile element (ACME). However, the contribution of ACME to USA300's success in SSTIs is not completely understood. We show that the constitutive ACME-encoded arginine-deiminase system (Arc) allows USA300 to thrive in acidic environments that mimic human skin. Consequently, the ACME-Arc system drives excessive production of host polyamines, compounds uniquely toxic to S. aureus. To mitigate this, ACME also encodes SpeG, a polyamine-resistance enzyme that is essential for combating excess host polyamines in a murine SSTI model. Inhibiting host polyamine production not only restored ΔspeG persistence within infected wounds but also severely altered the host healing process, implying that polyamines play an integral role in coordinating the wound-healing response. Together, these data underscore the functional modularity of ACME and its contribution to the success of USA300 CA-MRSA.

Regulatory twist and synergistic role of metabolic coinducer- and response regulator-mediated CbbR-cbbI interactions in Rhodopseudomonas palustris CGA010.

Rhodopseudomonas palustris assimilates CO2 by the Calvin-Benson-Bassham (CBB) reductive pentose phosphate pathway. Most genes required for a functional CBB pathway are clustered into the cbbI and cbbII operons, with the cbbI operon subject to control by a LysR transcriptional activator, CbbR, encoded by cbbR, which is divergently transcribed from the cbbLS genes (encoding form I RubisCO) of the cbbI operon. Juxtaposed between the genes encoding CbbR and CbbLS are genes that encode a three-protein two-component system (CbbRRS system) that functions to modify the ability of CbbR to regulate cbbLS expression. Previous studies indicated that the response regulators, as well as various coinducers (effectors), specifically influence CbbR-promoter interactions. In the current study, it was shown via several experimental approaches that the response regulators and coinducers act synergistically on CbbR to influence cbbLS transcription. Synergistic effects on the formation of specific CbbR-DNA complexes were quantified using surface plasmon resonance (SPR) procedures. Gel mobility shift and DNA footprint analyses further indicated structural changes in the DNA arising from the presence of response regulators and coinducer molecules binding to CbbR. Based on previous studies, and especially emphasized by the current investigation, it is clear that protein complexes influence promoter activity and the cbbLS transcription machinery.

Virulence strategies of the dominant USA300 lineage of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA).

Methicillin-resistant Staphylococcus aureus (MRSA) poses a serious threat to worldwide health. Historically, MRSA clones have strictly been associated with hospital settings, and most hospital-associated MRSA (HA-MRSA) disease resulted from a limited number of virulent clones. Recently, MRSA has spread into the community causing disease in otherwise healthy people with no discernible contact with healthcare environments. These community-associated MRSA clones (CA-MRSA) are phylogenetically distinct from traditional HA-MRSA clones, and CA-MRSA strains seem to exhibit hypervirulence and more efficient host : host transmission. Consequently, CA-MRSA clones belonging to the USA300 lineage have become dominant sources of MRSA infections in North America. The rise of this successful USA300 lineage represents an important step in the evolution of emerging pathogens and a great deal of effort has been exerted to understand how these clones evolved. Here, we review much of the recent literature aimed at illuminating the source of USA300 success and broadly categorize these findings into three main categories: newly acquired virulence genes, altered expression of common virulence determinants and alterations in protein sequence that increase fitness. We argue that none of these evolutionary events alone account for the success of USA300, but rather their combination may be responsible for the rise and spread of CA-MRSA.

Further unraveling the regulatory twist by elucidating metabolic coinducer-mediated CbbR-cbbI promoter interactions in Rhodopseudomonas palustris CGA010.

The cbb(I) region of Rhodopseudomonas palustris (Rp. palustris) contains the cbbLS genes encoding form I ribulose-1,5-bisphosphate (RuBP) carboxylase oxygenase (RubisCO) along with a divergently transcribed regulator gene, cbbR. Juxtaposed between cbbR and cbbLS are the cbbRRS genes, encoding an unusual three-protein two-component (CbbRRS) system that modulates the ability of CbbR to influence cbbLS expression. The nature of the metabolic signals that Rp. palustris CbbR perceives to regulate cbbLS transcription is not known. Thus, in this study, the CbbR binding region was first mapped within the cbbLS promoter by the use of gel mobility shift assays and DNase I footprinting. In addition, potential metabolic coinducers (metabolites) were tested for their ability to alter the cbbLS promoter binding properties of CbbR. Gel mobility shift assays and surface plasmon resonance analyses together indicated that biosynthetic intermediates such as RuBP, ATP, fructose 1,6-bisphosphate, and NADPH enhanced DNA binding by CbbR. These coinducers did not yield identical CbbR-dependent DNase I footprints, indicating that the coinducers caused significant changes in DNA structure. These in vitro studies suggest that cellular signals such as fluctuating metabolite concentrations are perceived by and transduced to the cbbLS promoter via the master regulator CbbR.

Arginine catabolic mobile element encoded speG abrogates the unique hypersensitivity of Staphylococcus aureus to exogenous polyamines.

Polyamines, including spermine (Spm) and spermidine (Spd), are aliphatic cations that are reportedly synthesized by all living organisms. They exert pleiotropic effects on cells and are required for efficient nucleic acid and protein synthesis. Here, we report that the human pathogen Staphylococcus aureus lacks identifiable polyamine biosynthetic genes, and consequently produces no Spm/Spd or their precursor compounds putrescine and agmatine. Moreover, while supplementing defined medium with polyamines generally enhances bacterial growth, Spm and Spd exert bactericidal effects on S. aureus at physiological concentrations. Small colony variants specifically lacking menaquinone biosynthesis arose after prolonged Spm exposure and exhibited reduced polyamine sensitivity. However, other respiratory-defective mutants were no less susceptible to Spm implying menaquinone itself rather than general respiration is required for full Spm toxicity. Polyamine hypersensitivity distinguishes S. aureus from other bacteria and is exhibited by all tested strains save those belonging to the USA-300 group of community-associated methicillin-resistant S. aureus (CA-MRSA). We identified one gene within the USA-300-specific arginine catabolic mobile element (ACME) encoding a Spm/Spd N-acetyltransferase that is necessary and sufficient for polyamine resistance. S. aureus encounters significant polyamine levels during infection; however, the acquisition of ACME encoded speG allows USA-300 clones to circumvent polyamine hypersensitivity, a peculiar trait of S. aureus.

SD-OCT to differentiate traumatic submacular hemorrhage types using automatic three-dimensional segmentation analysis.

Traumatic submacular hemorrhage may present with significant decrease in vision and may have varying outcomes. Following injury, the hemorrhage can collect either between the neurosensory retina and retinal pigment epithelium (RPE) or below the RPE. This differentiation may be important to prognosticate and to guide treatment. In two patients with post-traumatic submacular hemorrhage, Cirrius spectral domain high-definition optical coherence tomography (OCT) (Carl Zeiss Meditec, Dublin, CA) was used to differentiate traumatic submacular hemorrhage types using automation three-dimensional segmentation analysis. Based on the OCT findings, the patient with sub-RPE bleed was subjected to pneumatic displacement. En face C-scan imaging just below the RPE allowed for the diagnosis of the exact location of choroidal rupture that was masked due to hemorrhage.

Unravelling the regulatory twist--regulation of CO2 fixation in Rhodopseudomonas palustris CGA010 mediated by atypical response regulator(s).

In Rhodopseudomonas palustris CGA010, the LysR type regulator, CbbR, specifically controls transcription of the cbbLS genes encoding form I RubisCO. Previous genetic and physiological studies had indicated that a unique two-component (CbbRRS) system influences CbbR-mediated cbbLS transcription under conditions where CO(2) is the sole carbon source. In this study, we have established direct protein-protein interactions between the response regulators of the CbbRRS system and CbbR, using a variety of techniques. The bacterial two-hybrid system established a specific interaction between CbbR and CbbRR1 (response regulator 1 of the CbbRRS system), confirmed in vitro by chemical cross-linking. In addition, both response regulators (CbbRR1 and CbbRR2) played distinct roles in influencing the CbbR-cbbLS promoter interactions in gel mobility shift assays. CbbRR1 increased the binding affinity of CbbR at the cbb(I) promoter three- to fivefold while CbbRR2 appeared to stabilize CbbR binding. Specific interactions were further supported by surface plasmon resonance (SPR) analyses. In total, the results suggested that both response regulators, with no discernible DNA-binding domains, must interact with CbbR to influence cbbLS expression. Thus the CbbRRS system provides an additional level of transcriptional control beyond CbbR alone, and appears to be significant for potentially fine-tuning cbbLS expression in Rps. palustris.

Whole-body vibratory response study using a nonlinear multi-body model of seat-occupant system with viscoelastic flexible polyurethane foam.

Vehicle occupants are exposed to low frequency vibrations with possible harmful effects such as mild discomfort, lower back pain, and even injury to the spine. Occupational drivers and operators of heavy machinery are exposed to significantly longer duration and higher levels of vibration. Thus, the modeling and prediction of biodynamic response of seated occupants to such vibrations is very important. Since the properties of seating foam affect the response of the occupant, there is need for good models of seat-occupant systems through which the effects of foam properties on the dynamic response can be directly evaluated. A nonlinear planar seat-occupant model which incorporates the nonlinear viscoelastic behavior of seating foam has been developed. This model is used to study response of the occupant to harmonic excitation applied at the seat base, in terms of the frequency response in vertical and fore-and-aft directions, the deflection shapes at resonance, as well as the seat-to-head-transmissibility. In addition, to better understand the role of flexible polyurethane foam in characterizing the system behavior, the response of a single-degree-of-freedom foam-block system is also studied. The effects of different masses riding on the foam block and undergoing vertical vibrations at different acceleration levels are also investigated.

Integrative control of carbon, nitrogen, hydrogen, and sulfur metabolism: the central role of the Calvin-Benson-Bassham cycle.

Nonsulfur purple (NSP) photosynthetic bacteria use the Calvin-Benson-Bassham (CBB) reductive pentose phosphate pathway for the reduction of CO(2) via ribulose 1,5-bisphosphate (RuBP) carboxylase-oxygenase (RubisCO), as a means to build cell mass during chemoautotrophic or photoautotrophic conditions. In addition, the CBB pathway plays an important role in maintaining redox balance during photoheterotrophic growth conditions. In this communication we describe protein-protein interactions between two transcriptional regulators CbbR and RegA and the possible role of the CbbX protein in regulating the CBB pathway in Rhodobacter sphaeroides. In Rhodopseudomonas palustris, the CbbR and the CbbRRS system (a three-protein, two-component regulatory system) regulate the CBB pathway. Moreover, derepression of the nitrogenase complex, and the production of hydrogen gas, appears to be a common mechanism to balance the redox potential in RubisCO-compromised strains of NSP photosynthetic bacteria.