RESUMO
The marine diazotroph Crocosphaera watsonii provides fixed carbon (C) and nitrogen (N) to open-ocean regimes, where nutrient deficiency controls productivity. The growth of Crocosphaera can be limited by low phosphorus (P) concentrations in these oligotrophic environments. Biomarkers such as the high-affinity ABC transporter phosphate-binding gene, pstS, are commonly used to monitor when such organisms are under P stress; however, transcriptional regulation of these markers is often complex and not well-understood. In this study, we interrogated changes in pstS transcript levels in C. watsonii cells under P starvation, and in response to added dissolved inorganic phosphorus (DIP), dissolved organic phosphorus (DOP), and changing light levels. We observed elevated relative pstS transcript levels in C. watsonii WH8501 at DIP concentrations below 60 and above 20 nmol · L-1 . Transcript levels were suppressed by both inorganic and bioavailable organic phosphorus; however, the P stress response was more sensitive to DIP than DOP sources. Increasing light intensity resulted in increased relative pstS transcript abundances independently of low external P, and seemed to exacerbate the physiological effects of P stress. The variable response to different P compounds and rapid and transient influence of high light on pstS transcript abundances suggests that pstS is an indicator of internal P status in Crocosphaera.
Assuntos
Cianobactérias , Fósforo , Fixação de Nitrogênio , Proteínas de Transporte de FosfatoRESUMO
Crocosphaera watsonii is a marine cyanobacterium that frequently inhabits low phosphate environments in oligotrophic oceans. While C. watsonii has the ability to fix atmospheric nitrogen, its growth may be limited by availability of phosphorus. Biomarkers that indicate cellular phosphorus status give insight into how P-limitation can affect the distribution of nitrogen-fixing cyanobacterial populations. However, adaptation to phosphorus stress is complex and one marker may not be sufficient to determine when an organism is P-limited. In this study, we characterized the transcription of key genes, activated during phosphorus stress in C. watsonii WH8501, to determine how transcription changed during the phosphorus stress response. Transcription of pstS, which encodes a high-affinity phosphate binding protein, was discovered to be quickly up-regulated in phosphorus-depleted cells as an immediate stress response; however, its transcription declined after a period of phosphorus starvation. In addition, diel regulation of pstS in C. watsonii WH8501 complicates the interpretation of this marker in field applications. Transcription of the gene coding for the arsenite efflux protein, arsB, was upregulated after pstS in phosphorus limited cells, but it remained upregulated at later stages of phosphorus limitation. These results demonstrate that a single molecular marker does not adequately represent the entire phosphorus stress response in C. watsonii WH8501. Using both markers, the variations in transcriptional response over a range of degrees of phosphorus limitation may be a better approach for defining cellular phosphorus status.
Assuntos
Biomarcadores/metabolismo , Cianobactérias/metabolismo , Fixação de Nitrogênio/efeitos dos fármacos , Fósforo/farmacologia , Ritmo Circadiano/efeitos dos fármacos , Ritmo Circadiano/genética , Cianobactérias/efeitos dos fármacos , Cianobactérias/genética , Cianobactérias/crescimento & desenvolvimento , Perfilação da Expressão Gênica , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Genes Bacterianos , Fixação de Nitrogênio/genética , Fotossíntese/efeitos dos fármacos , Fotossíntese/genética , Transcrição Gênica/efeitos dos fármacosRESUMO
Ring closing metathesis (RCM) reactions of α-methylene-ß-lactams are used to construct strained 11- and 12-membered macrocycles that mimic key structural elements of phyllostictine A. The highest yield and stereoselectivity was achieved making 12-membered macrocycle Z-19 with use of a p-methoxyphenyl group on the lactam nitrogen. Interestingly, substrate concentration had an important influence on the stereochemical course of the reaction. A simplified analogue produced using this approach displays phytotoxic activity against Chlamydomonas reinhardtii suggesting that the α-methylene-ß-lactam subunit is responsible, at least in part, for the herbicidal activity of phyllostictine A.
Assuntos
Compostos Azabicíclicos/química , Azetidinas/química , Chlamydomonas reinhardtii/efeitos dos fármacos , Herbicidas/farmacologia , Compostos Heterocíclicos com 3 Anéis/farmacologia , Chlamydomonas reinhardtii/crescimento & desenvolvimento , Ciclização , Relação Dose-Resposta a Droga , Herbicidas/síntese química , Herbicidas/química , Compostos Heterocíclicos com 3 Anéis/síntese química , Compostos Heterocíclicos com 3 Anéis/química , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
There is growing public urgency to close equity gaps in health and development by addressing inequities at multiple levels of children's developmental ecosystems. Current measurement strategies obscure the dynamic structural and relational patterns of oppression, adversity, and disadvantage that children can experience in their local intimate developmental ecosystem, as well as the leverage points that are necessary to change them. The purpose of this study is to examine the relationship between a universally available measure of neighborhood socio-economic context, the National Neighborhood Equity Index (NNEI), and a population measure of early child development and well-being, the Early Development Instrument (EDI). Data from a convenience sample of 144,957 kindergarteners in neighborhoods across the US demonstrate that children living in neighborhoods with more equity barriers are more likely to be on vulnerable developmental trajectories than those who reside in neighborhoods without any equity barriers. A multi-dimensional measurement approach that incorporates both the EDI and the NNEI can be used to quantify ethnoracialized patterns of structural disadvantage during critical periods of health development. These measures can inform community action to intervene early in the lifecourse to optimize children's health development trajectories at a population level.
RESUMO
BACKGROUND: Faecal shedding of SARS-CoV-2 has raised concerns about transmission through faecal microbiota transplantation procedures. Validation parameters of authorised tests for SARS-CoV-2 RNA detection in respiratory samples are described in product labelling, whereas the published methods for SARS-CoV-2 detection from faecal samples have not permitted a robust description of the assay parameters. We aimed to develop and validate a test specifically for detection of SARS-CoV-2 in human stool. METHODS: In this validation study, we evaluated performance characteristics of a reverse transcriptase real-time PCR (RT-rtPCR) test for detection of SARS-CoV-2 in human stool specimens by spiking stool with inactivated SARS-CoV-2 material. A modified version of the US Centers for Disease Control and Prevention RT-rtPCR SARS-CoV-2 test was used for detection of viral RNA. Analytical sensitivity was evaluated in freshly spiked stool by testing two-fold dilutions in replicates of 20. Masked samples were tested by a second laboratory to evaluate interlaboratory reproducibility. Short-term (7-day) stability of viral RNA in stool samples was assessed with four different stool storage buffers (phosphate-buffered saline, Cary-Blair medium, Stool Transport and Recovery [STAR] buffer, and DNA/RNA Shield) kept at -80°C, 4°C, and ambient temperature (approximately 21°C). We also tested clinical stool and anal swab specimens from patients who were SARS-CoV-2 positive by nasopharyngeal testing. FINDINGS: The lower limit of detection of the assay was found to be 3000 viral RNA copies per g of original stool sample, with 100% detection across 20 replicates assessed at this concentration. Analytical sensitivity was diminished by approximately two times after a single freeze-thaw cycle at -80°C. At 100 times the limit of detection, spiked samples were generally stable in all four stool storage buffers tested for up to 7 days, with maximum changes in mean threshold cycle values observed at -80°C storage in Cary-Blair medium (from 29·4 [SD 0·27] at baseline to 30·8 [0·17] at day 7; p<0·0001), at 4°C storage in DNA/RNA Shield (from 28·5 [0·15] to 29·8 [0·09]; p=0·0019), and at ambient temperature in STAR buffer (from 30·4 [0·24] to 32·4 [0·62]; p=0·0083). 30 contrived SARS-CoV-2 samples were tested by a second laboratory and were correctly identified as positive or negative in at least one of two rounds of testing. Additionally, SARS-CoV-2 RNA was detected using this assay in the stool and anal swab specimens of 11 of 23 individuals known to be positive for SARS-CoV-2. INTERPRETATION: This is a sensitive and reproducible assay for detection of SARS-CoV-2 RNA in human stool, with potential uses in faecal microbiota transplantation donor screening, sewage monitoring, and further research into the effects of faecal shedding on the epidemiology of the COVID-19 pandemic. FUNDING: National Institute of Allergy and Infectious Diseases, US National Institutes of Health; Center for Biologics Evaluation and Research, US Food and Drug Administration.
Assuntos
COVID-19 , SARS-CoV-2 , COVID-19/diagnóstico , Humanos , Pandemias , RNA Viral/genética , Reprodutibilidade dos Testes , SARS-CoV-2/genéticaRESUMO
An outbreak of infectious bronchitis caused by the IBVPR03 strain of the Massachusetts genotype affected H-120 vaccinated laying hens in South Brazil. We investigated the cross protection of the vaccine by assessing the traqueal ciliostasis, virus recovery, and histopathological changes typically observed in the respiratory tract. Although the IBVPR03 strain is S1-genotyped as Massachusetts with a high genomic similarity to the H-120 vaccine strains, surprisingly, we found no tropism or pathogenicity to the trachea in birds infected with this strain. On the other hand, we observed ovarian and testicle lesions. Here, we show that, despite belonging in the Massachusetts genotype, the IBVPR03 pathotype differs from the expected respiratory pattern, causing instead marked histopathological changes in the gonads, so far not associated with this group.
Assuntos
Infecções por Coronavirus/veterinária , Gônadas/virologia , Vírus da Bronquite Infecciosa/isolamento & purificação , Doenças das Aves Domésticas/virologia , Animais , Brasil , Galinhas , Infecções por Coronavirus/patologia , Infecções por Coronavirus/virologia , Feminino , Genótipo , Gônadas/patologia , Vírus da Bronquite Infecciosa/classificação , Vírus da Bronquite Infecciosa/genética , Vírus da Bronquite Infecciosa/patogenicidade , Masculino , Doenças das Aves Domésticas/patologia , Traqueia/patologia , Traqueia/virologia , VirulênciaRESUMO
The first total synthesis of phyllostictine A (PA) is reported, which confirms the structure of this fungal metabolite and its (6S,7R,8S)-stereochemistry. Both synthetic PA and an analogue containing the 5-methylene-1,5-dihydro-2H-pyrrol-2-one nucleus exhibit µM inhibitory activity in root growth assays against Arabidopsis thaliana, indicating that this heterocyclic subunit is key to the herbicidal activity of the natural product.
Assuntos
Arabidopsis/efeitos dos fármacos , Compostos Heterocíclicos com 3 Anéis/farmacologia , Raízes de Plantas/efeitos dos fármacos , Arabidopsis/crescimento & desenvolvimento , Relação Dose-Resposta a Droga , Compostos Heterocíclicos com 3 Anéis/síntese química , Compostos Heterocíclicos com 3 Anéis/química , Estrutura Molecular , Raízes de Plantas/crescimento & desenvolvimentoRESUMO
This work aimed to investigate mechanisms underlying the inflammatory response caused by Potamotrygon motoro stingray venom (PmV) in mouse paws. Pre-treatment of animals with a mast cell degranulation inhibitor (cromolyn) diminished edema (62% of inhibition) and leukocyte influx into the site of PmV injection. Promethazine (histamine type 1 receptor antagonist) or thioperamide (histamine type 3 and 4 receptor antagonist) also decreased edema (up to 30%) and leukocyte numbers, mainly neutrophils (40-50 %). Cimetidine (histamine type 2 receptor antagonist) had no effect on PmV-induced inflammation. In the RBL-2H3 lineage of mast cells, PmV caused proper cell activation, in a dose-dependent manner, with release of PGD2 and PGE2. In addition, the role of COXs products on PmV inflammatory response was evaluated. Indomethacin (COX-1/COX-2 inhibitor) or etoricoxib (COX-2 inhibitor) partially diminished edema (around 20%) in PmV-injected mice. Indomethacin, but not etoricoxib, modulated neutrophil influx into the site of venom injection. In conclusion, mast cell degranulation and histamine, besides COXs products, play an important role in PmV-induced reaction. Since PmV mechanism of action remains unknown, hindering accurate treatment, clinical studies can be performed to validate the prescription of antihistaminic drugs, besides NSAIDs, to patients injured by freshwater stingrays.
Assuntos
Edema/patologia , Elasmobrânquios/metabolismo , Venenos de Peixe/toxicidade , Histamina/toxicidade , Leucócitos/efeitos dos fármacos , Mastócitos/efeitos dos fármacos , Animais , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Ciclo-Oxigenase 1/metabolismo , Inibidores de Ciclo-Oxigenase 2/farmacologia , Dinoprostona/metabolismo , Edema/induzido quimicamente , Etoricoxib , Antagonistas dos Receptores Histamínicos H1/farmacologia , Masculino , Proteínas de Membrana/antagonistas & inibidores , Proteínas de Membrana/metabolismo , Camundongos , Prometazina/farmacologia , Prostaglandina D2/metabolismo , Piridinas/farmacologia , Ratos , Sulfonas/farmacologiaRESUMO
Expression of nifH in 28 surface water samples collected during fall 2007 from six stations in the vicinity of the Cape Verde Islands (north-east Atlantic) was examined using reverse transcription-polymerase chain reaction (RT-PCR)-based clone libraries and quantitative RT-PCR (RT-qPCR) analysis of seven diazotrophic phylotypes. Biological nitrogen fixation (BNF) rates and nutrient concentrations were determined for these stations, which were selected based on a range in surface chlorophyll concentrations to target a gradient of primary productivity. BNF rates greater than 6 nmolN l(-1) h(-1) were measured at two of the near-shore stations where high concentrations of Fe and PO(4)(3-) were also measured. Six hundred and five nifH transcripts were amplified by RT-PCR, of which 76% are described by six operational taxonomic units, including Trichodesmium and the uncultivated UCYN-A, and four non-cyanobacterial diazotrophs that clustered with uncultivated Proteobacteria. Although all five cyanobacterial phylotypes quantified in RT-qPCR assays were detected at different stations in this study, UCYN-A contributed most significantly to the pool of nifH transcripts in both coastal and oligotrophic waters. A comparison of results from RT-PCR clone libraries and RT-qPCR indicated that a γ-proteobacterial phylotype was preferentially amplified in clone libraries, which underscores the need to use caution interpreting clone-library-based nifH studies, especially when considering the importance of uncultivated proteobacterial diazotrophs.
Assuntos
Proteínas de Bactérias/genética , Fixação de Nitrogênio , Nitrogenase/genética , Proteobactérias/enzimologia , Água do Mar/microbiologia , Cabo Verde , Clorofila/análise , Clorofila A , Cianobactérias/enzimologia , Cianobactérias/genética , Biblioteca Gênica , Ferro/análise , Filogenia , Proteobactérias/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Água do Mar/análise , Microbiologia da ÁguaRESUMO
Canine parvovirus (CPV) is an emerged pathogen in dogs, first isolated in 1978 in the USA. The original 1978 strain was designated CPV type 2 (CPV-2). However, analysis of CPV isolates in the USA by restriction enzymes and monoclonal antibodies have shown that around the year 1979 a CPV variant strain, designated CPV type 2a (CPV-2a), became widespread. Subsequently, a new antigenic strain, designated CPV type 2b (CPV-2b), was also observed by analysis of CPV isolates from various parts of the world, although the proportion of each strains was different between countries. In this study, the Haemagglutination Inhibition (HI) test with a panel of monoclonal antibodies was used to type canine parvovirus strains in 29 fecal samples collected from symptomatic dogs from 1980 to 1986 and from 1990 to 1995. The results showed a strong predominance of the antigenic type 2a indicating that the CPV epizooty in Brazil followed the same pattern observed in European and Asian countries.
O Parvovírus Canino (CPV) é um patógeno emergente em cães, isolado pela primeira vez em 1978, nos Estados Unidos. A amostra original de 1978 foi designada CPV tipo 2 (CPV-2). Entretanto, análises de isolados de CPV dos Estados Unidos, por enzimas de restrição e anticorpos monoclonais demonstraram que cerca de 1979, uma amostra variante, designada CPV tipo 2a (CPV-2a) tornou-se prevalente. Subseqüentemente, uma nova amostra antigênica, designada CPV tipo 2b (CPV-2b) também foi observada por análises de isolados de CPV de várias partes do mundo, embora a proporção fosse diferente entre os países. Nesse estudo, foi utilizado o teste de Inibição da Hemaglutinação (HI) com um painel de anticorpos monoclonais para a tipagem de 29 amostras fecais de parvovirus canino, coletadas de cães sintomáticos de 1980 a 1986 e de 1990 a 1995. Os resultados indicaram uma forte predominância do tipo antigênico 2a indicando que a epizootia de CPV no Brasil seguiu o mesmo padrão observados na Europa e países Asiáticos.