8,293 research outputs found
A review of ammonia-oxidizing bacteria and archaea in Chinese soils
Ammonia (NH3) oxidation, the first and rate-limiting step of nitrification, is a key step in the global Nitrogen (N) cycle. Major advances have been made in recent years in our knowledge and understanding of the microbial communities involved ammonia oxidation in a wide range of habitats, including Chinese agricultural soils. In this mini-review, we focus our attention on the distribution and community diversity of ammonia-oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA) in Chinese soils with variable soil properties and soil management practices. The niche differentiation of AOB and AOA in contrasting soils have been functionally demonstrated using DNA-SIP (stable isotope probing) methods, which have shown that AOA dominate nitrification processes in acidic soils, while AOB dominated in neutral, alkaline and N-rich soils. Finally, we discuss the composition and activity of ammonia oxidizer in paddy soils, as well as the mitigation of the greenhouse gas nitrous oxide (N2O) emissions and nitrate leaching via inhibition of nitrification by both AOB and AOA
catena-Poly[[[diaquabis(1H-indole-3-acetato-κO)cobalt(II)]-μ-4,4′-bipyridine-κ2 N:N′] tetrahydrate]
The 4,4′-bipyridine spacer in the title compound, [Co(C10H8NO2)2(C10H8N2)(H2O)2]·4H2O, links the diaquacobalt(II) dicarboxylate units into a linear chain; the metal atom lies on a center of inversion in an octahedral environment. The coordinated and uncoordinated water molecules interact through O—H⋯O hydrogen bonds to form a three-dimensional network
Opportunistic Wiretapping/Jamming: A New Attack Model in Millimeter-Wave Wireless Networks
While the millimeter-wave (mmWave) communication is robust against the
conventional wiretapping attack due to its short transmission range and
directivity, this paper proposes a new opportunistic wiretapping and jamming
(OWJ) attack model in mmWave wireless networks. With OWJ, an eavesdropper can
opportunistically conduct wiretapping or jamming to initiate a more hazardous
attack based on the instantaneous costs of wiretapping and jamming. We also
provide three realizations of the OWJ attack, which are mainly determined by
the cost models relevant to distance, path loss and received power,
respectively. To understand the impact of the new attack on mmWave network
security, we first develop novel approximation techniques to characterize the
irregular distributions of wiretappers, jammers and interferers under three OWJ
realizations. With the help of the results of node distributions, we then
derive analytical expressions for the secrecy transmission capacity to depict
the network security performance under OWJ. Finally, we provide extensive
numerical results to illustrate the effect of OWJ and to demonstrate that the
new attack can more significantly degrade the network security performance than
the pure wiretapping or jamming attack
Lactulose enhances neuroplasticity to improve cognitive function in early hepatic encephalopathy
Lactulose is known to improve cognitive function in patients with early hepatic encephalopathy; however, the underlying mechanism remains poorly understood. In the present study, we investigated the behavioral and neurochemical effects of lactulose in a rat model of early hepatic encephalopathy induced by carbon tetrachloride. Immunohistochemistry showed that lactulose treatment promoted neurogenesis and increased the number of neurons and astrocytes in the hippocampus. Moreover, lactulose-treated rats showed shorter escape latencies than model rats in the Morris water maze, indicating that lactulose improved the cognitive impairments caused by hepatic encephalopathy. The present findings suggest that lactulose effectively improves cognitive function by enhancing neuroplasticity in a rat model of early hepatic encephalopathy
Consistent responses of soil microbial taxonomic and functional attributes to mercury pollution across China
Background: The ecological consequences of mercury (Hg) pollution—one of the major pollutants worldwide—on
microbial taxonomic and functional attributes remain poorly understood and largely unexplored. Using soils from two
typical Hg-impacted regions across China, here, we evaluated the role of Hg pollution in regulating bacterial
abundance, diversity, and co-occurrence network. We also investigated the associations between Hg contents and the
relative abundance of microbial functional genes by analyzing the soil metagenomes from a subset of those sites.
Results: We found that soil Hg largely influenced the taxonomic and functional attributes of microbial communities in
the two studied regions. In general, Hg pollution was negatively related to bacterial abundance, but positively related
to the diversity of bacteria in two separate regions. We also found some consistent associations between soil Hg
contents and the community composition of bacteria. For example, soil total Hg content was positively related to the
relative abundance of Firmicutes and Bacteroidetes in both paddy and upland soils. In contrast, the methylmercury
(MeHg) concentration was negatively correlated to the relative abundance of Nitrospirae in the two types of soils.
Increases in soil Hg pollution correlated with drastic changes in the relative abundance of ecological clusters within the
co-occurrence network of bacterial communities for the two regions. Using metagenomic data, we were also able to
detect the effect of Hg pollution on multiple functional genes relevant to key soil processes such as element cycles
and Hg transformations (e.g., methylation and reduction).
Conclusions: Together, our study provides solid evidence that Hg pollution has predictable and significant effects on
multiple taxonomic and functional attributes including bacterial abundance, diversity, and the relative abundance of
ecological clusters and functional genes. Our results suggest an increase in soil Hg pollution linked to human activities
will lead to predictable shifts in the taxonomic and functional attributes in the Hg-impacted areas, with potential
implications for sustainable management of agricultural ecosystems and elsewhere
Antibiotic resistance in urban green spaces mirrors the pattern of industrial distribution
Urban green spaces are closely related to the activities and health of urban residents. Turf grass and soil are two major interfaces between the environmental and human microbiome, which represent potential pathways for the
spread of antibiotic resistance genes (ARGs) from environmental to human microbiome through skin-surface contact. However, the information regarding the prevalence of ARGs in urban green spaces and drivers in shaping their distribution patterns remain unclear. Here, we profiled a wide spectrum of ARGs in grass phyllosphere and soils from 40 urban parks across Greater Melbourne, Australia, using high throughput quantitative PCR. A total of 217 and 218 unique ARGs and MGEs were detected in grass phyllosphere and soils, respectively,
conferring resistance to almost all major classes of antibiotics commonly used in human and animals. The plant microbiome contained a core resistome, which occupied > 84% of the total abundance of ARGs. In contrast, no core resistome was identified in the soil microbiome. The difference between plant and soil resistome composition was attributed to the difference in bacterial community structure and intensity of environmental and anthropogenic influence. Most importantly, the abundance of ARGs in urban green spaces was significantly
positively related to industrial factors including total number of business, number of manufacturing, and number of electricity, gas, water and waste services in the region. Structural equation models further revealed that
industrial distribution was a major factor shaping the ARG profiles in urban green spaces after accounting for multiple drivers. These findings have important implications for mitigation of the potential risks posed by ARGs
to urban residents
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