Filamentous, heterocyst-forming cyanobacteria belonging to taxonomic subsections IV and V are developmentally complex multicellular organisms capable of differentiating an array of cell and filament ...types, including motile hormogonia. Hormogonia exhibit gliding motility that facilitates dispersal, phototaxis, and the establishment of nitrogen-fixing symbioses. The gene regulatory network (GRN) governing hormogonium development involves a hierarchical sigma factor cascade, but the factors governing the activation of this cascade are currently undefined. Here, using a forward genetic approach, we identified
, a gene encoding a putative hybrid histidine kinase that functions upstream of the sigma factor cascade. The deletion of
produced nonmotile filaments that failed to display hormogonium morphology or accumulate hormogonium-specific proteins or polysaccharide. Targeted transcriptional analyses using reverse transcription-quantitative PCR (RT-qPCR) demonstrated that hormogonium-specific genes both within and outside the sigma factor cascade are drastically downregulated in the absence of
and that
may be subject to indirect, positive autoregulation via
and
Orthologs of HrmK are ubiquitous among, and exclusive to, heterocyst-forming cyanobacteria. Collectively, these results indicate that
functions upstream of the sigma factor cascade to initiate hormogonium development, likely by modulating the phosphorylation state of an unknown protein that may serve as the master regulator of hormogonium development in heterocyst-forming cyanobacteria.
Filamentous cyanobacteria are morphologically complex, with several representative species amenable to routine genetic manipulation, making them excellent model organisms for the study of development. Furthermore, two of the developmental alternatives, nitrogen-fixing heterocysts and motile hormogonia, are essential to establish nitrogen-fixing symbioses with plant partners. These symbioses are integral to global nitrogen cycles and could be artificially recreated with crop plants to serve as biofertilizers, but to achieve this goal, detailed understanding and manipulation of the hormogonium and heterocyst gene regulatory networks may be necessary. Here, using the model organism
, we identify a previously uncharacterized hybrid histidine kinase that is confined to heterocyst-forming cyanobacteria as the earliest known participant in hormogonium development.
The course of pathophysiological mechanisms involved in fragile X-associated tremor/ataxia syndrome (FXTAS) remains largely unknown. Previous proteomics and metabolomics studies conducted in blood ...samples collected from FMR1 premutation carriers with FXTAS reported abnormalities in energy metabolism, and precursors of gluconeogenesis showed significant changes in plasma expression levels in FMR1 premutation carriers who developed FXTAS. We conducted an analysis of postmortem human brain tissues from 44 donors, 25 brains with FXTAS, and 19 matched controls. We quantified the metabolite relative abundance in the inferior temporal gyrus and the cerebellum using untargeted mass spectrometry (MS)-based metabolomics. We investigated how the metabolite type and abundance relate to the number of cytosine-guanine-guanine (CGG) repeats, to markers of neurodegeneration, and to the symptoms of FXTAS. A metabolomic analysis identified 191 primary metabolites, the data were log-transformed and normalized prior to the analysis, and the relative abundance was compared between the groups. The changes in the relative abundance of a set of metabolites were region-specific with some overlapping results; 22 metabolites showed alterations in the inferior temporal gyrus, while 21 showed differences in the cerebellum. The relative abundance of cytidine was decreased in the inferior temporal gyrus, and a lower abundance was found in the cases with larger CGG expansions; oleamide was significantly decreased in the cerebellum. The abundance of 11 metabolites was influenced by changes in the CGG repeat number. A histological evaluation found an association between the presence of microhemorrhages in the inferior temporal gyrus and a lower abundance of 2,5-dihydroxypyrazine. Our study identified alterations in the metabolites involved in the oxidative-stress response and bioenergetics in the brains of individuals with FXTAS. Significant changes in the abundance of cytidine and oleamide suggest their potential as biomarkers and therapeutic targets for FXTAS.
Most species of filamentous cyanobacteria are capable of gliding motility, likely via a conserved type IV pilus-like system that may also secrete a motility-associated polysaccharide. In a subset of ...these organisms, motility is achieved only after the transient differentiation of hormogonia, which are specialized filaments that enter a nongrowth state dedicated to motility. Despite the fundamental importance of hormogonia to the life cycles of many filamentous cyanobacteria, the molecular regulation of hormogonium development is largely undefined. To systematically identify genes essential for hormogonium development and motility in the model heterocyst-forming filamentous cyanobacterium
, a forward genetic screen was employed. The first gene identified using this screen, designated
, encodes a putative O-linked β-
-acetylglucosamine transferase (OGT). The deletion of
abolished motility, while ectopic expression of
induced hormogonium development even under hormogonium-repressing conditions. Transcription of
is rapidly upregulated (1 h) following hormogonium induction, and an OgtA-GFPuv fusion protein localized to the cytoplasm. In developing hormogonia, accumulation of PilA but not HmpD is dependent on
Reverse transcription-quantitative PCR (RT-qPCR) analysis indicated equivalent levels of
transcript in the wild-type and Δ
mutant strains, while a reporter construct consisting of the intergenic region in the 5' direction of
fused to
produced lower levels of fluorescence in the Δ
mutant strain than in the wild type. The production of hormogonium polysaccharide in the Δ
mutant strain is reduced compared to that in the wild type but comparable to that in a
deletion strain. Collectively, these results imply that
-GlcNAc protein modification regulates the accumulation of PilA via a posttranscriptional mechanism in developing hormogonia.
Filamentous cyanobacteria are among the most developmentally complex prokaryotes. Species such as
develop an array of cell types, including nitrogen-fixing heterocysts, spore-like akinetes, and motile hormogonia, that function in dispersal as well as the establishment of nitrogen-fixing symbioses with plants and fungi. These symbioses are major contributors to global nitrogen fixation. Despite the fundamental importance of hormogonia to the life cycle of filamentous cyanobacteria and the establishment of symbioses, the molecular regulation of hormogonium development is largely undefined. We employed a genetic screen to identify genes essential for hormogonium development and motility in
The first gene identified using this screen encodes a eukaryotic-like O-linked β-
-acetylglucosamine transferase that is required for accumulation of PilA in hormogonia.
Wildfires cause significant changes in natural habitats and can impact lizard populations. Through changes in the thermal environment, reduced prey availability, and increased exposure to parasite ...vectors, wildfires affect lizard physiology, immunity, and health. We sampled 56 Tropidurus oreadicus lizards from Cerrado savannas of Brazil living in two adjacent sites: one burned 14 days before the study, and the other unburned for 6 years. We logged the air temperatures of those sites throughout fieldwork. We assessed the short‐term possible homeostatic imbalances caused by the fires via measuring body mass, circulating levels of corticosterone (CORT), leukocytes profile changes in heterophile‐lymphocyte ratios (HLRs), innate immunity using the bacterial killing assay (BKA), and the diagnosis of hemoparasites using molecular techniques. The air temperature was significantly higher in the burned site. There was no difference in lizard body mass between the two sites, suggesting that prey availability was not affected by the wildfire. While parasite presence was seemingly not affected by fire, the timing of initial parasite infection for animals in the study was unknown, so we also evaluated parasitism as an independent variable relative to the other metrics. Our results showed that parasitic infections lead to reduced bactericidal capacity and body mass in lizards, suggesting clinical disease and depletion of innate immune resources. Moreover, we observed increased HLR with fire and parasitic infections and a strong negative correlation with BKA. These findings suggest that the increased environmental temperature following wildfires may lead to increased CORT and decreased BKA.
Wildfires cause significant changes in natural habitats and can impact lizard populations. Parasitic infections lead to reduced bactericidal capacity and body mass in lizards, suggesting clinical disease and depletion of innate immune resources. Moreover, increased HLR with fire and parasitic infections and a strong negative correlation with BKA. Increased environmental temperature following wildfires may lead to increased CORT and decreased BKA.
Research highlights
The main short‐term effect of fire on these lizards appears to be changes related to thermal physiology.
Animals recently exposed to wildfires had increased circulating glucocorticoid levels and reduced bactericidal capacity.
Heterophile‐lymphocyte ratios (HLR) were higher in wildfire sites and animals with hemoparasite infections.
The HLR was negatively correlated with bacterial killing capacity, and this relationship varied depending on exposure to wildfire
Circulating corticosterone levels were elevated in response to wildfire but were not related to the presence of a hemoparasite infection.
Hemoparasite infections caused by haemosporidians can lead to decreased body mass and bactericidal capacity in lizards.
Wildfires may not affect Tropidurus oreadicus prey availability as lizards did not show a significant difference in body mass between recently burned and unburned areas.
Wildfires do not appear to influence hemoparasite prevalence in T. oreadicus lizards in the short term.
Environmental temperatures were higher at wildfire sites after the burn, which along with other habitat changes, may lead to some of the observed physiological changes.
Most species of filamentous cyanobacteria are capable of gliding motility, likely via a conserved type IV pilus-like system that may also secrete a motility-associated polysaccharide. In a subset of ...these organisms, motility is achieved only after the transient differentiation of hormogonia, which are specialized filaments that enter a nongrowth state dedicated to motility. Despite the fundamental importance of hormogonia to the life cycles of many filamentous cyanobacteria, the molecular regulation of hormogonium development is largely undefined. To systematically identify genes essential for hormogonium development and motility in the model heterocyst-forming filamentous cyanobacterium Nostoc punctiforme, a forward genetic screen was employed. The first gene identified using this screen, designated ogtA, encodes a putative O-linked β-N-acetylglucosamine transferase (OGT). The deletion of ogtA abolished motility, while ectopic expression of ogtA induced hormogonium development even under hormogonium-repressing conditions. Transcription of ogtA is rapidly upregulated (1 h) following hormogonium induction, and an OgtA-GFPuv fusion protein localized to the cytoplasm. In developing hormogonia, accumulation of PilA but not HmpD is dependent on ogtA. Reverse transcription-quantitative PCR (RT-qPCR) analysis indicated equivalent levels of pilA transcript in the wild-type and ΔogtA mutant strains, while a reporter construct consisting of the intergenic region in the 5' direction of pilA fused to gfp produced lower levels of fluorescence in the ΔogtA mutant strain than in the wild type. The production of hormogonium polysaccharide in the ΔogtA mutant strain is reduced compared to that in the wild type but comparable to that in a pilA deletion strain. Collectively, these results imply that O-GlcNAc protein modification regulates the accumulation of PilA via a posttranscriptional mechanism in developing hormogonia.
Crude glycerol and swine manure are residues with exponential production in Mexico, nonetheless, they have the potential to generate hydrogen from the fermentation process. For this reason, this ...study has evaluated the optimization of hydrogen yield from crude glycerol and swine manure, using the response surface methodology. The response surface methodology helps in the compression of the mixture of crude glycerol/ swine manure, with the production of hydrogen as a result, which improves the yields of the process, reducing variability and time of development. A central composite design was employed with two factors, six axial points and four central points. The two factors evaluated were crude glycerol and swine manure concentrations, which were examined over a range of 4 to 10 g L−1 and 5 to 15 g L−1, respectively. This study demonstrated that the thermal pretreatment method is still the most suitable method to be applied, mainly in the preparation of hydrogen-producing inoculum. The maximum hydrogen yield was 142.46 mL per gram of volatile solid added. It used up 21.56% of the crude glycerol (2.75 g L−1) and 78.44% (10 g L−1) of the swine manure, maintaining a carbon/nitrogen ratio of 18.06, with a fermentation time of 21 days. The response surface methodology was employed to maximize the hydrogen production of crude glycerol/swine manure ratios by the optimization of factors with few assays and less operational cost.
In this work, a sulfated titanium dioxide (STi) catalyst obtained from a commercial TiO
2
precursor was synthesized and characterized. The catalyst was sulfated by the simple impregnation method with ...H
2
SO
4
and subsequently calcined at different temperatures. The synthesized catalyst was characterized by X-ray Diffraction (XRD), Energy-Dispersive Spectroscopy (EDS), and Scanning Electron Microscopy (SEM). The sulfated catalyst was thermally treated at different temperatures (100, 200, 400, and 600 °C) and evaluated in oleic acid esterification reactions by varying the concentration of the catalyst during the conversion of oleic acid to methyl oleate. The conversion was measured from the variation of the acid index (AI)° and free fatty acids (FFA) during the reaction. The STi catalyst obtained was compared with two homogeneous catalysts, H
2
SO
4
and ferric sulfate Fe
2
(SO
4
)
3
, evaluating the reaction time in the conversion, from which improvements in the reaction performance of the catalyst synthesized in this work were observed versus the two homogeneous catalysts mentioned earlier. Catalyst reuse cycles were also evaluated as well as their performance in the esterification of waste cooking oil. The best catalyst yields reached values close to 86% in a reaction time of 6 h.
Objectives
To compare maternal and perinatal outcomes among women with obesity, overweight, and normal body mass index, associated with COVID‐19 infection during pregnancy and postpartum.
Method
...Prospective Cohort Study, within the REBRACO (Brazilian Network of COVID‐19 in Pregnancy) multicenter initiative. Confirmed positive cases of SARS‐CoV‐2 were included, and women categorized into three groups according to their pre‐pregnancy BMI: obesity (BMI ≥ 30), overweight (BMI <30 but >25), and normal BMI. Sociodemographic, clinical, and obstetric characteristics and different maternal and perinatal outcomes were compared, and a multiple regression analysis was performed to investigate factors independently associated with adverse maternal and perinatal outcomes.
Results
Two hundred eighty‐nine women positive for SARS‐CoV‐2 infection were considered, and 202 had available data on maternal BMI for the current analysis. Overall, 72 (35.6%)obese, 68 (33.6%) overweight, and 60 (29.7%) normal BMI. Obesity was associated with increased adverse clinical outcomes including sepsis (P = 0.02), acute respiratory distress syndrome (P = 0.002), and the need for mechanical ventilation (P = 0.044). Considering perinatal outcomes, a multiple regression model confirmed obesity as an independent factor associated with adverse results (adjusted odds ratio 3.73, 95% CI 1.54–9.08).
Conclusion
Obesity and overweight were associated with worse clinical outcomes, severe/critical COVID‐19, and adverse perinatal outcomes.
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