Salmonella enterica subsp. enterica (S. enterica) is a significant public health concern and is estimated to cause more than 300,000 deaths annually. Nowadays, the vaccines available for human ...Salmonellosis prevention are all targeting just one serovar, i.e., S. Typhi, leaving a huge potential risk of Salmonella disease epidemiology change. In this study, we explored the strategy of multiple immunodominant O-epitopes co-expression in S. enterica serovars and evaluated their immunogenicity to induce cross-immune responses and cross-protections against S. Paratyphi A, S. Typhimurium and S. Enteritidis. We found that nucleotide sugar precursors CDP-Abe and CDP-Par (or CDP-Tyv) could be utilized by S. enterica serovars simultaneously, exhibiting O2&O4 (or O4&O9) double immunodominant O-serotypes without obvious growth defects. More importantly, a triple immunodominant O2&O4&O9 O-serotypes could be achieved in S. Typhimurium by improving the substrate pool of CDP-Par, glycosyltransferase WbaV and flippase Wzx via a dual-plasmid overexpressing system. Through immunization in a murine model, we found that double or triple O-serotypes live attenuated vaccine candidates could induce significantly higher heterologous serovar-specific antibodies than their wild-type parent strain. Meanwhile, the bacterial agglutination, serum bactericidal assays and protection efficacy experiments had all shown that these elicited serum antibodies are cross-reactive and cross-protective. Our work highlights the potential of developing a new type of live attenuated Salmonella vaccines against S. Paratyphi A, S. Typhimurium and S. Enteritidis simultaneously.
The Moderate Resolution Spectroradiometer (MODIS) sensor has provided near real-time estimates of gross primary production (GPP) since March 2000. We compare four years (2000 to 2003) of ...satellite-based calculations of GPP with tower eddy CO2 flux-based estimates across diverse land cover types and climate regimes. We examine the potential error contributions from meteorology, leaf area index (LAI)/fPAR, and land cover. The error between annual GPP computed from NASA's Data Assimilation Office's (DAO) and tower-based meteorology is 28%, indicating that NASA's DAO global meteorology plays an important role in the accuracy of the GPP algorithm. Approximately 62% of MOD15-based estimates of LAI were within the estimates based on field optical measurements, although remaining values overestimated site values. Land cover presented the fewest errors, with most errors within the forest classes, reducing potential error. Tower-based and MODIS estimates of annual GPP compare favorably for most biomes, although MODIS GPP overestimates tower-based calculations by 20%-30%. Seasonally, summer estimates of MODIS GPP are closest to tower data, and spring estimates are the worst, most likely the result of the relatively rapid onset of leaf-out. The results of this study indicate, however, that the current MODIS GPP algorithm shows reasonable spatial patterns and temporal variability across a diverse range of biomes and climate regimes. So, while continued efforts are needed to isolate particular problems in specific biomes, we are optimistic about the general quality of these data, and continuation of the MOD17 GPP product will likely provide a key component of global terrestrial ecosystem analysis, providing continuous weekly measurements of global vegetation production.
China national air quality monitoring network has become the core data source for air quality assessment and management in China. However, during network construction, the significant change in ...numbers of monitoring sites with time is easily ignored, which brings uncertainty to air quality assessments. This study aims to analyze the impact of change in numbers of stations on national and regional air quality assessments in China during 2013–18. The results indicate that the change in numbers of stations has different impacts on fine particulate matter (PM
2.5
) and ozone concentration assessments. The increasing number of sites makes the estimated national and regional PM
2.5
concentration slightly lower by 0.6–2.2 µg m
−3
and 1.4–6.0 µg m
−3
respectively from 2013 to 2018. The main reason is that over time, the monitoring network expands from the urban centers to the suburban areas with low population densities and pollutant emissions. For ozone, the increasing number of stations affects the long-term trends of the estimated concentration, especially the national trends, which changed from a slight upward trend to a downward trend in 2014–15. Besides, the impact of the increasing number of sites on ozone assessment exhibits a seasonal difference at the 0.05 significance level in that the added sites make the estimated concentration higher in winter and lower in summer. These results suggest that the change in numbers of monitoring sites is an important uncertainty factor in national and regional air quality assessments, that needs to be considered in long-term concentration assessment, trend analysis, and trend driving force analysis.
In recent years, China has implemented several measures to improve air quality. The Beijing-Tianjin-Hebei (BTH) region is one area that has suffered from the most serious air pollution in China and ...has undergone huge changes in air quality in the past few years. How to scientifically assess these change processes remain the key issue in further improving the air quality over this region in the future. To evaluate the changes in major air pollutant emissions over this region, this paper employs ensemble Kalman filtering (EnKF) for integrating the national ground monitoring pollutant observation data and the Nested Air Quality Prediction Modeling System (NAQPMS) simulation data to inversely estimate the emission rates of SO
2
, NO
X
, CO, and primary PM
2.5
over BTH region in February from 2014 to 2019. The results show that SO
2
, NO
X
, CO, and primary PM
2.5
emissions in the BTH region decreased in February from 2014 to 2019 by 83%, 37%, 41%, and 42%, while decreases in Beijing during this period were 86%, 67%, 59%, and 65%, respectively. Compared with the prior emission inventory, the inversion emission inventory reduces the uncertainty of multi-pollutant simulation in the BTH region, with simulated root mean square errors of the monthly average concentrations of SO
2
, NO
X
, PM
2.5
, and CO reduced by 41%, 30%, 31%, and 22%, respectively. The average uncertainties of SO
2
, NO
X
, PM
2.5
, and CO inversion emissions in 2014–19 are ±14.03% yr
−1
, ±28.91% yr
−1
, ±126.15% yr
−1
, and ±43.58% yr
−1
. Compared with the uncertainty of MEIC emission, the uncertainties of all species changed by +2% yr
−1
, −2% yr
−1
, −26% yr
−1
, and −4% yr
−1
, respectively. The spatial distribution results illustrate that air pollutant emissions are mainly distributed over the eastern and southern BTH regions. The spatial gap between the inversion emissions and MEIC emissions was further closed in 2019 compared to 2014. The results of this paper can provide a new reference for assessing changes in air pollution emissions over the BTH region in recent years and validating a bottom-up emission inventory.
Soils are highly variable at many spatial scales, which makes designing studies to accurately estimate the mean value of soil properties across space challenging. The spatial correlation structure is ...critical to develop robust sampling strategies (e.g., sample size and sample spacing). Current guidelines for designing studies recommend conducting preliminary investigation(s) to characterize this structure, but are rarely followed and sampling designs are often defined by logistics rather than quantitative considerations. The spatial variability of soils was assessed across ∼1 ha at 60 sites. Sites were chosen to represent key US ecosystems as part of a scaling strategy deployed by the National Ecological Observatory Network. We measured soil temperature (Ts) and water content (SWC) because these properties mediate biological/biogeochemical processes below- and above-ground, and quantified spatial variability using semivariograms to estimate spatial correlation. We developed quantitative guidelines to inform sample size and sample spacing for future soil studies, e.g., 20 samples were sufficient to measure Ts to within 10% of the mean with 90% confidence at every temperate and sub-tropical site during the growing season, whereas an order of magnitude more samples were needed to meet this accuracy at some high-latitude sites. SWC was significantly more variable than Ts at most sites, resulting in at least 10× more SWC samples needed to meet the same accuracy requirement. Previous studies investigated the relationship between the mean and variability (i.e., sill) of SWC across space at individual sites across time and have often (but not always) observed the variance or standard deviation peaking at intermediate values of SWC and decreasing at low and high SWC. Finally, we quantified how far apart samples must be spaced to be statistically independent. Semivariance structures from 10 of the 12-dominant soil orders across the US were estimated, advancing our continental-scale understanding of soil behavior.
Soil pH is often changed by anthropogenic activities such as agronomic management, land use or acidifying pollution, and is widely considered to be a dominant factor affecting soil nitrogen cycling. ...In this study, three purple soils originating from similar parent materials but varying in pH (5.7, 7.3, and 8.0), representing acidic, neutral and alkaline soils, were selected to determine the effect of background pH on net nitrification rate (NNR) and ammonia oxidizers (AOA and AOB). The background pH of each soil was modified to the pH of the other soils to investigate the effect of adjusted pH on NNR and ammonia oxidizers. Net nitrification rates varied significantly with adjusted pH in neutral soils but did not change in acidic and alkaline soils, suggesting that soil at neutral pH is more sensitive to changes in nitrification. The AOB abundance increased in neutral soils adjusted to high pH, whereas AOA decreased with increased pH in acidic and neutral soils, which indicated that the activity and abundance of AOA and AOB is the more important factor affecting nitrification in neutral soils. The ratios of AOA to AOB in the unmodified acidic, neutral and alkaline soils were 120, 1.55 and 0.07, respectively. The highest AOA and AOB abundances occurred in unmodified pH neutral soil. However, the highest NNR was found in alkaline soils (7.04 mg N kg−1 dry soil d−1), which was significantly higher than that in neutral and acidic soils (2.31 and − 0.23 mg N kg−1 dry soil d−1, respectively). These results indicate that substrate competition between AOA and AOB exists in neutral soils, which can provide insight and improve our understanding of microbial regulation of N cycling in terrestrial ecosystems.
•Responses of nitrification to adjusted pH vary among soils with different background pH.•Background pH selects ammonia oxidizers to affect nitrification in soils.•Low nitrification in neutral soil may due to competition between AOA & AOB for NH3.
Introduction
Anaerobic ammonium oxidation (anammox) plays a vital role in the global nitrogen cycle by oxidizing ammonium to nitrogen under anaerobic environments. However, the existence, abundance, ...and diversity of anammox bacteria between different temperatures are less studied, particularly in purple paddy soils.
Methods
13
C-DNA stable-isotope probe combined with Illumina MiSeq high-throughput sequencing was employed to explore soil abundance and diversity of anammox bacteria. In doing so, 40–60 cm depth soils from typical purple paddy soils in Chongqing, southwest China, were cultured under
12
CO
2
-labeled and
13
CO
2
-labeled at 35°C, 25°C, 15°C, and 5°C for 56 days.
Results and Discussion
Anammox bacteria were not labeled at all by
13
CO
2
at 5°C. The highest abundance of anammox bacteria was found at 25°C (3.52 × 10
6
~3.66 × 10
6
copies·g
−1
dry soil), followed by 35°C and 15°C (2.01 × 10
6
~2.37 × 10
6
copies·g
−1
dry soil) and almost no increase at 5°C. The relative abundance of
Candidatus Jettenia
sp. was higher at 25°C and 15°C, while
Candidatus Brocadia
sp. was higher at 35°C and 5°C. Our results revealed differences in anammox bacteria at different temperatures in purple paddy soils, which could provide a better understanding of soil N cycling regulated by anammox bacteria.
Imbalance in redox homeostasis is a major cause of age-related cognitive impairment. The endocannabinoid system (ECS) is a key player in regulating synaptic transmission, plasticity and memory. ...Increasing evidence indicates an important interplay between the two systems. However, how excessive oxidative stress could alter ECS and that, in turn, impairs its modulatory role in synaptic plasticity and cognitive function remains elusive. In the present study, we examined this causal link in D-galactose-induced oxidative rats. First, the reactive oxygen species generating enzymes, especially nitric oxide synthase (NOS), indeed show an elevated expression in D-galactose-treated rats, and this was correlated to an impaired hippocampal long-term potentiation (LTP) and spatial memory loss in animal behavioral tests. Second, the cannabinoid receptor type I (CB1)-mediated signing is known to regulate synaptic plasticity. We show that a decrease in CB1 and increase in degradation enzymes for CB1 ligand endocannabinoid anandamide all occurred to D-galactose-treated rats. Surprisingly, application of low-dose anandamide, known to reduce LTP under physiological condition, now acted to enhance LTP in D-galactose-treated rats, most likely resulted from the inhibition of GABAergic synapses. Furthermore, this reversal behavior of CB1-signaling could be fully simulated by a NOS inhibitor, diphenyleneiodonium. These observations suggest that interaction between redox dysfunction and ECS should contribute significantly to the impaired synaptic plasticity and memory loss in D-gal-treated rats. Therefore, therapies focusing on the balance of these two systems may shed lights on the treatment of age-related cognitive impairment in the future.
infections remain a big problem worldwide, causing enteric fever by
Typhi (or Paratyphi) or self-limiting gastroenteritis by non-typhoidal
(NTS) in healthy individuals. NTS may become invasive and ...cause septicemia in elderly or immuno-compromised individuals, leading to high mortality and morbidity. No vaccines are currently available for preventing NTS infection in human. As these invasive NTS are restricted to several O-antigen serogroups including B1, D1, C1, and C2, O-antigen polysaccharide is believed to be a good target for vaccine development. In this study, a strategy of O-serotype conversion was investigated to develop live attenuated
. Typhimurium vaccines against the major serovars of NTS infections. The immunodominant O4 serotype of
. Typhimurium was converted into O9, O7, and O8 serotypes through unmarked chromosomal deletion-insertion mutations. O-serotype conversion was confirmed by LPS silver staining and western blotting. All O-serotype conversion mutations were successfully introduced into the live attenuated
. Typhimurium vaccine S738 (Δ
Δ
) to evaluate their immunogenicity in mice model. The vaccine candidates induced high amounts of heterologous O-polysaccharide-specific functional IgG responses. Vaccinated mice survived a challenge of 100 times the 50% lethality dose (LD
) of wild-type
. Typhimurium. Protective efficacy against heterologous virulent
challenges was highly O-serotype related. Furthermore, broad-spectrum protection against
. Typhimurium,
. Enteritidis, and
. Choleraesuis was observed by co-vaccination of O9 and O7 O-serotype-converted vaccine candidates. This study highlights the strategy of expressing heterologous O-polysaccharides
genetic engineering in developing live attenuated
. Typhimurium vaccines against NTS infections.
Nitrogen-based fertilizer applications have an effect on nitrification and nitrifying microorganisms in acidic soils of agricultural and forest lands. However, the effect of different nitrogen (N) ...fertilizers on nitrification and nitrifying microorganisms in acidic Ultisols of the subtropical regions are not well studied. Here, we investigated the effect of ammonium sulfate and urea applications on nitrification and nitrifying microorganisms in acidic Ultisols of Jinyun Mountain. The abundance of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) amoA genes were quantitatively analyzed by real-time PCR. Our results indicated that there was a significant difference in soil pH among treatments and the maximum pH value (pH = 4.93) was recorded in urea addition due to the hydrolysis of urea. Similarly, significant differences in the content of NH
4
+
-N and NO
3
−
-N were observed among treatments. The result also revealed that urea addition had higher ammonium and nitrate than that of ammonium sulfate, and stimulated nitrification in acidic Ultisols, whereas nitrification was not stimulated by the application of ammonium sulfate. The net nitrification rate at the end of the experiment for control, ammonium sulfate, and urea treatment were −0.005, −0.003 and 0.004 mg N kg
−1
soil day
−1
respectively. Besides, the addition of urea significantly increased the AOA and AOB abundance. The abundance of AOA amoA gene was greater than AOB in all treatments. However, the ratio of AOA to AOB was lower in soils with ammonium sulfate and urea addition compared to control. This implies that N addition greatly stimulates AOB rather than AOA abundance. Therefore, AOB may be responsible for the higher nitrification potential in the urea added soil. In conclusion, urea addition significantly increased the content of ammonium, soil pH, AOA and AOB abundance, and stimulates nitrification. AOB may play a significant role in nitrification process in urea added acidic Ultisols.
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