mBio , IF:7.867 , 2021 Oct , V12 (5) : Pe0101321 doi: 10.1128/mBio.01013-21
Interactions between Viral Regulatory Proteins Ensure an MOI-Independent Probability of Lysogeny during Infection by Bacteriophage P1.
Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA.; Center for Phage Technology, Texas A&M University, College Station, Texas, USA.; Molecular and Environmental Plant Sciences, Texas A&M University, College Station, Texas, USA.; Department of Computer Science and Engineering, Texas A&M University, College Station, Texas, USA.
Phage P1 is a temperate phage which makes the lytic or lysogenic decision upon infecting bacteria. During the lytic cycle, progeny phages are produced and the cell lyses, and in the lysogenic cycle, P1 DNA exists as a low-copy-number plasmid and replicates autonomously. Previous studies at the bulk level showed that P1 lysogenization was independent of multiplicity of infection (MOI; the number of phages infecting a cell), whereas lysogenization probability of the paradigmatic phage lambda increases with MOI. However, the mechanism underlying the P1 behavior is unclear. In this work, using a fluorescent reporter system, we demonstrated this P1 MOI-independent lysogenic response at the single-cell level. We further observed that the activity of the major repressor of lytic functions (C1) is a determining factor for the final cell fate. Specifically, the repression activity of P1, which arises from a combination of C1, the anti-repressor Coi, and the corepressor Lxc, remains constant for different MOI, which results in the MOI-independent lysogenic response. Additionally, by increasing the distance between phages that infect a single cell, we were able to engineer a lambda-like, MOI-dependent lysogenization upon P1 infection. This suggests that the large separation of coinfecting phages attenuates the effective communication between them, allowing them to make decisions independently of each other. Our work establishes a highly quantitative framework to describe P1 lysogeny establishment. This system plays an important role in disseminating antibiotic resistance by P1-like plasmids and provides an alternative to the lifestyle of phage lambda. IMPORTANCE Phage P1 has been shown potentially to play an important role in disseminating antibiotic resistance among bacteria during lysogenization, as evidenced by the prevalence of P1 phage-like elements in animal and human pathogens. In contrast to phage lambda, a cell fate decision-making paradigm, P1 lysogenization was shown to be independent of MOI. In this work, we built a simple genetic model to elucidate this MOI independency based on the gene-regulatory circuitry of P1. We also proposed that the effective communication between coinfecting phages contributes to the lysis-lysogeny decision-making of P1 and highlighted the significance of spatial organization in the process of cell fate determination in a single-cell environment. Finally, our work provides new insights into different strategies acquired by viruses to interact with their bacterial hosts in different scenarios for their optimal survival.
PMID: 34517752
Plant Dis , IF:4.438 , 2021 Oct : PPDIS11202492RE doi: 10.1094/PDIS-11-20-2492-RE
Effects of Long-Term Bare Fallow During the Winter-Wheat Growth Season on the Soil Chemical Properties, Fungal Community Composition, and the Occurrence of Maize Fungal Diseases in North China.
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China.; Institute of Plant Protection, Hebei Academy of Agricultural and Forestry Sciences, Baoding 071000, China.
On the North China Plain, one of the most water-deficient regions in China, bare fallow has been implemented over a large-scale area to conserve water during the growth season of water-intensive winter wheat since 2015. However, the effects of this bare fallow on fungal community and the occurrence of crop diseases are poorly understood. Here we measured soil chemical properties, fungal community composition, and the occurrence of crop diseases after 15 years of long-term fallow (continuous maize or soybean) and non-fallow (maize-wheat rotation; soybean-wheat rotation) cropping systems. Bare fallow during the winter-wheat growth season significantly decreased soil organic matter, available nitrogen, and phosphorus. It also changed the composition of soil fungal communities, i.e., increased relative abundances of some potentially pathogenic species of Lectera, Fusarium, and Volutella but decreased beneficial Cladorrhium and Schizothecium. Meanwhile, the epidemic tendency of maize diseases changed correspondingly: the disease index of southern corn leaf blight and maize brown spot increased, but the incidence of stalk rot decreased compared with the non-fallow system. Soybean diseases were very mild regardless of the cropping system during the total experimental period. Network analysis demonstrated that the soil fungal diversity associated with maize diseases was affected by the decreased soil organic matter and available nitrogen and phosphorus. Our results suggest that bare fallow in the winter-wheat season affected the soil chemical properties, fungal community, and the occurrence of maize fungal diseases.
PMID: 33404273
Tree Physiol , IF:4.196 , 2021 Oct , V41 (10) : P1938-1952 doi: 10.1093/treephys/tpab038
Rejuvenation remodels transcriptional network to improve rhizogenesis in mature Juglans tree.
State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of National Forestry and Grassland Administration, Research Institute of Forestry, the Chinese Academy of Forestry, 1958 Box, Beijing 100091, China.; Institute of Computing Technology, Chinese Academy of Sciences, No.6 Kexueyuan South Road Zhongguancun, Haidian District, Beijing 100190, China.; Forestry Bureau of Luoning County, Luoning County, Luoyang City, Henan Province 471700, China.
Adventitious rooting of walnut species (Juglans L.) is known to be rather difficult, especially for mature trees. The adventitious root formation (ARF) capacities of mature trees can be significantly improved by rejuvenation. However, the underlying gene regulatory networks (GRNs) of rejuvenation remain largely unknown. To characterize such regulatory networks, we carried out the transcriptomic study using RNA samples of the cambia and peripheral tissues on the bottom of rejuvenated and mature walnut (Juglans hindsii x J. regia) cuttings during the ARF. The RNA sequencing data suggested that zeatin biosynthesis, energy metabolism and substance metabolism were activated by rejuvenation, whereas photosynthesis, fatty acid biosynthesis and the synthesis pathways for secondary metabolites were inhibited. The inter- and intra-module GRNs were constructed using differentially expressed genes. We identified 35 hub genes involved in five modules associated with ARF. Among these hub genes, particularly, beta-glucosidase-like (BGLs) family members involved in auxin metabolism were overexpressed at the early stage of the ARF. Furthermore, BGL12 from the cuttings of Juglans was overexpressed in Populus alba x P. glandulosa. Accelerated ARF and increased number of ARs were observed in the transgenic poplars. These results provide a high-resolution atlas of gene activity during ARF and help to uncover the regulatory modules associated with the ARF promoted by rejuvenation.
PMID: 34014320
Planta , IF:4.116 , 2021 Oct , V254 (5) : P94 doi: 10.1007/s00425-021-03747-5
Ceratocystis cacaofunesta differentially modulates the proteome in xylem-enriched tissue of cocoa genotypes with contrasting resistance to Ceratocystis wilt.
Departamento de Ciencias Biologicas (DCB), Centro de Biotecnologia e Genetica (CBG), Universidade Estadual de Santa Cruz (UESC), Ilheus, BA, 45662-900, Brazil.; Comissao Executiva de Planejamento da Lavoura Cacaueira (CEPLAC), Centro de Pesquisas do Cacau (CEPEC), Itabuna, BA, 45600-919, Brazil.; Departamento de Ciencias Biologicas (DCB), Centro de Biotecnologia e Genetica (CBG), Universidade Estadual de Santa Cruz (UESC), Ilheus, BA, 45662-900, Brazil. ronanxc@uesc.br.
MAIN CONCLUSION: Decreased accumulation of polyphenol oxidase, H2O2 accumulation, effective regulation of programmed cell death, and a protein predicted as allergenic can play key roles in cacao defense against Ceratocystis cacaofunesta. Ceratocystis wilt, caused by the fungus Ceratocystis cacaofunesta, has destroyed millions of Theobroma cacao trees in several countries of the Americas. Through proteomics, systems biology, and enzymatic analyses of infected stems, it was possible to infer mechanisms used by resistant (TSH1188) and susceptible (CCN51) cacao genotypes during infection. Protein extraction from xylem-enriched tissue of stems inoculated with the fungus and their controls 1 day after inoculation was carried out, followed by separation through two-dimensional gel electrophoresis and identification by mass spectrometry. Enzyme activity was determined at 1, 3, 7 and 15 days after inoculation. A total of 50 differentially accumulated distinct proteins were identified in the treatments of both genotypes and were classified into 10 different categories. An interaction network between homologous proteins from Arabidospsis thaliana was generated for each genotype, using the STRING database and Cytoscape software. Primary metabolism processes were apparently repressed in both genotypes. The resistance factors suggested for genotype TSH1188 were: H2O2 accumulation, effective regulation of programmed cell death, production of phytoalexins derived from tryptophan and furanocoumarins, and participation of a predicted allergenic protein with probable ribonuclease function inhibiting the germination and propagation of the fungus. In the susceptible genotype, it is possible that its recognition and signaling mechanism through proteins from the SEC14 family is easily overcome by the pathogen. Our results will help to better understand the interaction between cacao and one of its most aggressive pathogens, to create disease control strategies.
PMID: 34642817
Online Soc Netw Media , 2021 Oct : P100174 doi: 10.1016/j.osnem.2021.100174
Disinformed social movements: A large-scale mapping of conspiracy narratives as online harms during the COVID-19 pandemic.
Centre for Digital Governance, Hertie School, Berlin, Germany.; Media Measurement Limited, London, United Kingdom.
The Coronavirus pandemic was accompanied by uncertainty regarding appropriate treatments and policy reactions, which created a perfect breeding ground for the spread of conspiratorial anti-science narratives based on disinformation. Disinformation on public health may result in deadly consequences and hesitance to vaccinations is counted among the ten most severe threats to global public health by the United Nations. Conspiracy narratives, however, are a combination of disinformation, misinformation and rumour that are especially effective in drawing people to believe in post-factual claims. We monitored two established conspiracy narratives and their communities on Twitter, the anti-vaccination and anti-5G communities, before and during the first UK lockdown to assess whether they were able to grow their reach and influence broader public discourses on Twitter such as #Lockdown in the United Kingdom. Moreover, we make sense of conspiracy narratives as social movements, since they provide an option for self-identification and cognitive certainty in a rapidly changing information environment amid disruptive social distancing measures.
PMID: 34642647