Structures of complexes comprised of Fischerella transcription factor HetR with Anabaena DNA targets

HetR is an essential regulator of heterocyst development in cyanobacteria. Many mutations in HetR render Anabaena incapable of nitrogen fixation. The protein binds to a DNA palindrome upstream of hetP and other genes. We have determined the crystal structures of HetR complexed with palindromic DNA targets, 21, 23, and 29 bp at 2.50-, 3.00-, and 3.25-Å resolution, respectively. The highest-resolution structure shows fine details of specific protein–DNA interactions. The lower-resolution structures with longer DNA duplexes have similar interaction patterns and show how the flap domains interact with DNA in a sequence nonspecific fashion. Fifteen of 15 protein–DNA contacts predicted on the basis of the structure were confirmed by single amino acid mutations that abolished binding in vitro and complementation in vivo. A striking feature of the structure is the association of glutamate 71 from each subunit of the HetR dimer with three successive cytosines in each arm of the palindromic target, a feature that is conserved among all known heterocyst-forming cyanobacteria sequenced to date

The heterocyst regulatory protein HetP and its homologs modulate heterocyst commitment in Anabaena sp. strain PCC 7120

The commitment of differentiating cells to a specialized fate is fundamental to the correct assembly of tissues within a multicellular organism. Because commitment is often irreversible, entry into and progression through this phase of development must be tightly regulated. Under nitrogen-limiting conditions, the multicellular cyanobacterium Anabaena sp. strain PCC 7120 terminally commits ∼10% of its cells to become specialized nitrogen-fixing heterocysts. Although commitment is known to occur 9–14 h after the induction of differentiation, the factors that regulate the initiation and duration of this phase have yet to be elucidated. Here, we report the identification of four genes that share a functional domain and modulate heterocyst commitment: hetP (alr2818), asl1930, alr2902, and alr3234. Epistatic relationships between all four genes relating to commitment were revealed by deleting them individually and in combination; asl1930 and alr3234 acted most upstream to delay commitment, alr2902 acted next in the pathway to inhibit development, and hetP acted most downstream to drive commitment forward. Possible protein–protein interactions between HetP, its homologs, and the heterocyst master regulator, HetR, were assessed, and interaction partners were defined. Finally, patterns of gene expression for each homolog, as determined by promoter fusions to gfp and reverse transcription–quantitative PCR, were distinct from that of hetP in both spatiotemporal organization and regulation. We posit that a dynamic succession of protein–protein interactions modulates the timing and efficiency of the commitment phase of development and note that this work highlights the utility of a multicellular cyanobacterium as a model for the study of developmental processes

Characteristics and outcomes of neonates hospitalised with SARS-CoV-2 infection in the United Kingdom by variant: a prospective national cohort study

Objective Neonatal infection with wildtype SARS-CoV-2 is rare and good outcomes predominate. We investigated neonatal outcomes using national population-level data to describe the impact of different SARS-CoV-2 variants. Design Prospective population-based cohort study. Setting Neonatal, paediatric and paediatric intensive care inpatient care settings in the UK. Patients Neonates (first 28 days after birth) with confirmed SARS-CoV-2 infection who received inpatient care, March 2020 to April 2022. Neonates were identified through active national surveillance with linkage to national SARS-CoV-2 testing data, routinely recorded neonatal data, paediatric intensive care data and obstetric and perinatal mortality surveillance data. Outcomes Presenting signs, clinical course, severe disease requiring respiratory support are presented by the dominant SARS-CoV-2 variant in circulation at the time. Results 344 neonates with SARS-CoV-2 infection received inpatient care; breakdown by dominant variant: 146 wildtype, 123 alpha, 57 delta and 18 omicron. Overall, 44.7% (153/342) neonates required respiratory support; short-term outcomes were good with 93.6% (322/344) of neonates discharged home. Eleven neonates died: seven unrelated to SARS-CoV-2 infection, four were attributed to neonatal SARS-CoV-2 infection (case fatality 4/344, 1.2% 95% CI 0.3% to 3.0%) of which three were born preterm due to maternal COVID-19. More neonates were born very preterm (23/54) and required invasive ventilation (27/57) when delta variant was predominant, and all four SARS-CoV-2-related deaths occurred in this period. Conclusions Inpatient care for neonates with SARS-CoV-2 was uncommon. Although rare, severe neonatal illness was more common during the delta variant period, potentially reflecting more severe maternal disease and associated preterm birth. Trial registration number ISRCTN60033461

Association of antenatal or neonatal SARS-COV-2 exposure with developmental and respiratory outcomes, and healthcare usage in early childhood: A national prospective cohort study

Background: Perinatal exposure to SARS-CoV-2 may affect neurodevelopment before 12 months of age, but longer-term outcomes remain unknown. We examined whether antenatal or neonatal SARS-CoV-2 exposure compared with non-exposure is associated with neurodevelopment, respiratory symptoms, and health care usage in early childhood. Methods: This prospective national population-based cohort study was conducted in England and Wales, United Kingdom. We enrolled term-born children (≥37 weeks' gestation) with and without antenatal or neonatal exposure to SARS-CoV-2 infection by approaching parents of eligible children who were cared for in 87 NHS hospitals. Potential participants were identified through the national active surveillance studies of pregnant women and newborn infants hospitalised with confirmed SARS-CoV-2 infection conducted through the UK Obstetric Surveillance System and the British Paediatric Surveillance Unit. We defined antenatal and neonatal SARS-CoV-2 exposure as infants born to mothers hospitalised with confirmed SARS-CoV-2 infection between 14 + 0 and 36 + 6 weeks gestation and infants admitted to hospital with confirmed SARS-CoV-2 infection within the first 28 days after birth. Children born preterm or with major congenital anomaly or who were not residing in the UK were excluded. We assessed children's development (Ages and Stages Questionnaire 3rd Edition (ASQ-3); Ages and Stages Questionnaire Social-Emotional 2nd Edition (ASQ:SE-2)), respiratory symptoms (Liverpool Respiratory Symptom Questionnaire (LRSQ)) and health care usage (parent-completed questionnaire) at 21–32 months of age. Primary outcome: total ASQ-3 score, converted to z-scores. Secondary outcomes: ASQ:SE-2 z-scores; risk of delay in ASQ-3 domains; total LRSQ scores, converted to z-scores. Analyses were adjusted for children's age, sex, maternal ethnicity, parental education, and index of multiple deprivation. Findings: Between October 20, 2021 and January 27, 2023, we approached 668 and 1877 families out of 712 and 1917 potentially eligible participants in the exposed and comparison cohort. Of the 125 and 306 participants who were enrolled to the exposed and comparison cohort 121 and 301 participants completed the questionnaires and 96 and 243 participants were included in the analysis. In the age adjusted analysis, the mean total ASQ-3 z-score was lower in the exposed than the comparison cohort (−0.3, 95% CI: −0.6 to −0.05), however, when adjusted for sex, parental education, ethnicity and IMD quintile, there was no significant difference (difference in mean z-score = −0.2 95% CI: −0.5 to 0.03). SARS-CoV-2 exposure was associated with increased risk of delayed personal-social skills (odds ratio = 3.81; 95% CI: 1.07–13.66), higher ASQ:SE-2 total z-scores (difference in mean z-score = 0.4; 95% CI: 0.2–0.6) and increased risk of delayed social-emotional development (OR = 3.58, 95% CI: 1.30–9.83), after adjusting for sex, age at assessment, parental education, ethnicity and IMD quintile. The exposed cohort had a higher mean total LRSQ z-score than the comparison cohort (0.3 95% CI: 0–0.6) and higher inpatient (38% vs. 21%, p = 0.0001), outpatient (38% vs. 30%, p = 0.0090), and General Practitioner appointments (60% vs. 50%, p = 0.021) than the comparison cohort, after adjusting for sex, age at assessment, parental education, ethnicity and IMD quintile. No differences in other secondary outcomes between the exposed and comparison cohorts were found. Interpretation: Although the exposed cohort did not differ from the comparison cohort on the primary outcome, total ASQ-3 score, the exposed cohort were at greater risk of delayed social-emotional development, had a greater prevalence of respiratory symptoms and increased health care usage relative to the comparison cohort. The study is limited by the smaller sample size due to the low response rate and lack of clinical developmental assessments. Given the association of poor social-emotional development with antenatal or neonatal SARS-CoV-2 exposure, developmental screening, and follow-up of children with confirmed antenatal or neonatal SARS-CoV-2 infection may be warranted to identify those in need of early intervention. Funding: Action Medical Research for Children

Identification of S-nitrosated mitochondrial proteins by S-nitrosothiol difference in gel electrophoresis (SNO-DIGE): implications for the regulation of mitochondrial function by reversible S-nitrosation

The S-nitrosation of mitochondrial proteins as a consequence of NO metabolism is of physiological and pathological significance. We previously developed a MitoSNO (mitochondria-targeted S-nitrosothiol) that selectively S-nitrosates mitochondrial proteins. To identify these S-nitrosated proteins, here we have developed a selective proteomic methodology, SNO-DIGE (S-nitrosothiol difference in gel electrophoresis). Protein thiols in control and MitoSNO-treated samples were blocked, then incubated with copper(II) and ascorbate to selectively reduce S-nitrosothiols. The samples were then treated with thiol-reactive Cy3 (indocarbocyanine) or Cy5 (indodicarbocyanine) fluorescent tags, mixed together and individual protein spots were resolved by 2D (two-dimensional) gel electrophoresis. Fluorescent scanning of these gels revealed S-nitrosated proteins by an increase in Cy5 red fluorescence, allowing for their identification by MS. Parallel analysis by Redox-DIGE enabled us to distinguish S-nitrosated thiol proteins from those which became oxidized due to NO metabolism. We identified 13 S-nitrosated mitochondrial proteins, and a further four that were oxidized, probably due to evanescent S-nitrosation relaxing to a reversible thiol modification. We investigated the consequences of S-nitrosation for three of the enzymes identified using SNO-DIGE (aconitase, mitochondrial aldehyde dehydrogenase and α-ketoglutarate dehydrogenase) and found that their activity was selectively and reversibly inhibited by S-nitrosation. We conclude that the reversible regulation of enzyme activity by S-nitrosation modifies enzymes central to mitochondrial metabolism, whereas identification and functional characterization of these novel targets provides mechanistic insight into the potential physiological and pathological roles played by this modification. More generally, the development of SNO-DIGE facilitates robust investigation of protein S-nitrosation across the proteome

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

HetP and its three homologues : regions necessary for function of HetP and requirement of homologues for fixation of nitrogen in the filamentous cyanobacterium Anabaena sp. strain PCC 7120

M.S. University of Hawaii at Manoa 2013.Includes bibliographical references.The filamentous cyanobacterium Anabaena sp. strain PCC 7120 is a Gram-negative prokaryote that performs oxygenic photosynthesis. In addition to being an obligate phototroph, Anabaena is capable of differentiating specialized nitrogen-fixing cells called heterocysts. The development of terminally-differentiated heterocyst cells occurs in the absence of fixed nitrogen and forms a one-dimensional pattern along the filament of vegetative cells. The exchange of intercellular signals controls the regulated spacing of the heterocyst cells that on average arise every tenth cell along the filament (Figure 1). The formation of heterocyst cells effectively separates the oxygen-labile nitrogenase complex from oxygen-evolving photosynthesis that occurs in vegetative cells. Heterocysts and vegetative cells are mutually interdependent. Heterocyst cells lack photosystem II and the capacity to fix carbon and must rely on the vegetative cells for sources of reductant. In return, heterocysts supply the filament with fixed nitrogen (Cumino et al. 2007; Marcozzi et al 2009). The development of two distinct cell types in a simple one-dimensional pattern makes Anabaena a simple example of cellular differentiation and pattern formation