mSphere最新文献

{"title":"Divergence and convergence in epiphytic and endophytic phyllosphere bacterial communities of rice landraces.","authors":"Pratibha Sanjenbam, Deepa Agashe","doi":"10.1128/msphere.00765-24","DOIUrl":"https://doi.org/10.1128/msphere.00765-24","url":null,"abstract":"<p><p>Phyllosphere-associated microbes can significantly alter host plant fitness, with distinct functions provided by bacteria inhabiting the epiphytic (external surface) vs endophytic niches (internal leaf tissue). Hence, it is important to understand the assembly and stability of these phyllosphere communities, especially in field conditions. Broadly, epiphytic communities should encounter more environmental fluctuations and frequent immigration, whereas endophytic microbiota should face stronger host selection. As a result, we expect greater variability in epiphytic than endophytic communities. We analyzed the structure and stability of leaf phyllosphere microbiota of four traditionally cultivated rice landraces and one commercial variety from northeast India grown in the field for 3 consecutive years, supplemented with opportunistic sampling of eight other landraces. Epiphytic and endophytic bacterial communities shared dominant core genera such as <i>Methylobacterium</i> and <i>Sphingomonas</i>. Consistent with an overall strong environmental effect, both communities varied more across sampling years than across host landraces. Seeds sampled from a focal landrace did not support vertical transmission of phyllosphere bacteria, suggesting that both types of communities are assembled anew each generation. Despite these points of convergence, epiphytic communities had distinct composition and significantly higher microbial load and were more rich, diverse, modular, and unstable than endophytic communities. Finally, focused sampling of one landrace across developmental stages showed that the divergence between the two types of communities arose primarily at the flowering stage. Thus, our results show both convergent and divergent patterns of community assembly and composition in distinct phyllosphere niches in rice, identifying key bacterial genera and host developmental stages that may aid agricultural interventions to increase rice yield.IMPORTANCEPhyllosphere (leaf-associated) microbes significantly impact plant fitness, making it crucial to understand how these communities are assembled and maintained. While many studies have analyzed epiphytic (surface) phyllosphere communities, we have a relatively poor understanding of endophytic communities which colonize the very distinct niche formed inside leaf tissues. We found that across several rice landraces, both communities are largely colonized by the same core genera, indicating divergence at the species level across the two leaf niches and highlighting the need to understand the mechanisms underlying this divergence. Surprisingly, both epiphytic and endophytic communities were only weakly shaped by the host landrace, with a much greater role for environmental factors that likely vary over time. Thus, microbiome-based agricultural interventions for increasing productivity could perhaps be generalized across rice varieties but would need to account for the temporal instability of the microbiot","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142546506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Immunomodulatory activity of omadacycline <i>in vitro</i> and in a murine model of acute lung injury.","authors":"Madeline Sanders, Paul Beringer","doi":"10.1128/msphere.00671-24","DOIUrl":"https://doi.org/10.1128/msphere.00671-24","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Cystic fibrosis (CF) is characterized by chronic airway obstruction, infection, and inflammation leading to progressive loss of lung function and eventual respiratory failure. Omadacycline, a tetracycline antibiotic, demonstrates &lt;i&gt;in vitro&lt;/i&gt; activity against key CF pathogens, substantial lung penetration, and increasing clinical evidence for the treatment of lung infections in people with CF (PwCF). Preliminary &lt;i&gt;in vitro&lt;/i&gt; data demonstrate that omadacycline exhibits anti-inflammatory activity. This study aims to determine the anti-inflammatory effects of omadacycline &lt;i&gt;in vitro&lt;/i&gt; and in a murine model of lipopolysaccharide (LPS)-induced lung neutrophilia. &lt;i&gt;In vitro&lt;/i&gt;, THP-1-derived macrophages were treated with omadacycline (20-100 µg/mL) 30 minutes prior to LPS stimulation. Pro-inflammatory cytokine (TNF-α, IL-1β/6), chemokine (CXCL-1/2), and MMP-9 levels were analyzed after 24 hours by ELISA. Omadacycline's effects on IL-8-induced human neutrophil chemotaxis were also investigated. &lt;i&gt;In vivo&lt;/i&gt;, omadacycline (2.5-30 mg/kg), comparators dexamethasone (1 mg/kg), and azithromycin (30 mg/kg) were administered 1 hour before and 6 hours after intranasal LPS challenge, respectively. Leukocyte counts and differentials in bronchoalveolar lavage fluid (BALF), inflammatory mediator levels in BALF and lung homogenates, pulmonary edema markers, and the severity of lung injury were evaluated 24 hours or 48 hours post-challenge. Treatment with omadacycline &lt;i&gt;in vitro&lt;/i&gt; resulted in significant, dose-dependent reductions in IL-6, CXCL-1, and MMP-9 expression and inhibition of IL-8-induced neutrophil chemotaxis. &lt;i&gt;In vivo&lt;/i&gt;, omadacycline yielded protective and therapeutic effects by reducing the production of proinflammatory cytokines and chemokines and neutrophil infiltration into the lungs, along with modestly improving lung injury severity. These preclinical results suggest that omadacycline may provide dual anti-bacterial and anti-inflammatory activities relevant to chronic lung infection treatment in PwCF.IMPORTANCENontuberculous mycobacteria, particularly &lt;i&gt;Mycobacterium abscessus&lt;/i&gt; complex (MABSC), are a major concern for people with cystic fibrosis (PwCF) due to their association with deteriorating lung function. A substantial barrier to effective treatment is the limited number of safe and effective antibiotics. Omadacycline offers a potential advancement in managing MABSC infections in cystic fibrosis due to its activity, effective penetration into pulmonary secretions, improved tolerability, and good oral bioavailability as shown in healthy volunteers. Our study is the first to explore omadacycline's effects in a model of sterile lung inflammation and acute lung injury. We found that omadacycline not only has potent anti-bacterial properties but also exhibits anti-inflammatory effects, reducing lung inflammation and injury in our preclinical models. These findings underscore omadacycline's potential as a dual-action the","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142546508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Circulating extracellular vesicles from severe COVID-19 patients induce lung inflammation.","authors":"Huifeng Qian, Ruoxi Zang, Ruoyang Zhang, Guoping Zheng, Guanguan Qiu, Jianbiao Meng, Jiangmei Wang, Jie Xia, Ruoqiong Huang, Zhenkai Le, Qiang Shu, Jianguo Xu","doi":"10.1128/msphere.00764-24","DOIUrl":"https://doi.org/10.1128/msphere.00764-24","url":null,"abstract":"<p><p>Circulating extracellular vesicles (EVs) have been associated with the development of COVID-19 due to their roles in viral infection, inflammatory response, and thrombosis. However, the direct induction of lung inflammation by circulating EVs from severe COVID-19 patients remains unknown. EVs were extracted from the plasma of severe COVID-19 patients admitted to intensive care and healthy controls. To study the effect of COVID-19 EVs on lung inflammation, mice were intratracheally instilled with EVs. To examine the proinflammatory effects of EVs <i>in vitro</i>, bone marrow-derived macrophages were treated with EVs. COVID-19 but not control EVs triggered lung inflammation, as assessed by total protein level, total cell count, neutrophil count, and levels of proinflammatory cytokines in the bronchoalveolar lavage. COVID-19 EVs also promoted M1 polarization of alveolar macrophages <i>in vivo</i>. Treatment of bone marrow-derived macrophages with COVID-19 EVs enhanced the M1 phenotype and augmented the production of IL-1β, IL-6, and TNF-α. In summary, circulating EVs from severe COVID-19 patients induce lung inflammation in mice. EVs could become a potential therapeutic target for alleviating lung injury in COVID-19.</p><p><strong>Importance: </strong>Extracellular vesicles (EVs) have been reported to facilitate cytokine storm, coagulation, vascular dysfunction, and the spread of the virus in COVID-19. The direct role of circulating EVs from severe COVID-19 patients in lung injury remains unrecognized. Our study demonstrated that plasma EVs obtained from severe COVID-19 patients induced lung inflammation and polarization of alveolar macrophages <i>in vivo</i>. <i>In vitro</i> experiments also revealed the proinflammatory effects of COVID-19 EVs. The present study sheds fresh insight into the mechanisms of COVID-19-induced lung injury, highlighting EVs as a potential therapeutic target in combating the disease.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142546504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kinase function of TgTKL1 is essential for its role in <i>Toxoplasma</i> propagation and pathogenesis.","authors":"Dima Hajj Ali, Ramu Anandakrishnan, Vern B Carruthers, Rajshekhar Y Gaji","doi":"10.1128/msphere.00779-24","DOIUrl":"https://doi.org/10.1128/msphere.00779-24","url":null,"abstract":"<p><p>The Tyrosine Kinase-Like (TKL) family of proteins are a set of poorly studied kinases that have garnered attention in recent years for their role in <i>Toxoplasma</i> biology. The <i>Toxoplasma</i> genome contains eight TKL kinases, of which six have been predicted to be important for parasite propagation. We have previously shown that TgTKL1 is a nuclear kinase that is critical for the parasite lytic cycle and is essential for acute virulence in the animal model. However, the contribution of the kinase domain to the functioning of TgTKL1 was not known. Hence to determine the significance of its catalytic function, we first validated that TgTKL1 is a true kinase using purified recombinant protein. Furthermore, we successfully generated a TgTKL1 kinase mutant strain of <i>Toxoplasma</i> via CRISPR-Cas9 gene editing. Our studies revealed that the kinase mutant of TgTKL1 displays defects in parasite growth and host-cell invasion. Additionally, loss of kinase function alters the transcriptomic profile of the parasite, including downregulation of the invasion-related gene, TgSUB1. Importantly, this dysregulation of TgSUB1 expression leads to defects in post-exocytosis processing of micronemal proteins, an event critical for normal host-cell invasion. Furthermore, the TgTKL1 kinase mutant is completely avirulent in the mouse model of acute toxoplasmosis. Since the loss of kinase function leads to phenotypic manifestations seen previously with TgTKL1 knockout parasites, we conclude that kinase activity is important for TgTKL1 function in <i>Toxoplasma</i> propagation and virulence.</p><p><strong>Importance: </strong><i>Toxoplasma gondii</i> is a protozoan parasite that can cause life-threatening disease in humans. Hence, identifying key factors required for parasite growth and pathogenesis is important to develop novel therapeutics. We have previously shown that a member of the TKL protein kinase family, TgTKL1, is a plant-like kinase that is required for effective Toxoplasma growth <i>in vitro</i> and essential for virulence <i>in vivo</i>. Herein, we show that the TgTKL1 is, indeed, a <i>bona fide</i> kinase, and loss of its kinase function in the Toxoplasma leads to similar defects seen in parasites with complete loss of TgTKL1. More specifically, the TgTKL1 kinase mutant exhibits defects in parasite growth, host-cell invasion, gene expression profile, and virulence in the animal model. Together, these findings suggest that TgTKL1 is a true kinase, and loss of its kinase activity leads to disruption of TgTKL1 function in <i>Toxoplasma</i>.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142546509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of global change drivers on the expression of pathogenicity and stress genes in dryland soil fungi.","authors":"Adriana L Romero-Olivares, Andrea Lopez, Jovani Catalan-Dibene, Scott Ferrenberg, Samuel E Jordan, Brooke Osborne","doi":"10.1128/msphere.00658-24","DOIUrl":"https://doi.org/10.1128/msphere.00658-24","url":null,"abstract":"<p><p>The impacts of global climate change on dryland fungi have been understudied even though fungi are extremely sensitive to changes in the environment. Considering that many fungi are pathogens of plants and animals, including humans, their responses to anthropogenic change could have important implications for public health and food security. In this study, we investigated the potential physiological responses (i.e., metatranscriptomics) of pathogenicity and stress in dryland fungi exposed to global change drivers, drought, and the physical disturbance associated with land use. Specifically, we wanted to assess if there was an increase in the transcription of genes associated to pathogenicity and stress in response to global change drivers. In addition, we wanted to investigate which pathogenicity and stress genes were consistently differentially expressed under the different global change conditions across the heterogeneous landscape (i.e., microsite) of the Chihuahuan desert. We observed increased transcription of pathogenicity and stress genes, with specific genes being most upregulated in response to global change drivers. Additionally, climatic conditions linked to different microsites, such as those found under patches of vegetation, may play a significant role. We provide evidence supporting the idea that environmental stress caused by global change could contribute to an increase of pathogenicity as global climate changes. Specifically, increases in the transcription of stress and virulence genes, coupled with variations in gene expression, could lead to the onset of pathogenicity. Our work underscores the importance of studying dryland fungi exposed to global climate change and increases in existing fungal pathogens, as well as the emergence of new fungal pathogens, and consequences to public health and food security.</p><p><strong>Importance: </strong>The effects of global climate change on dryland fungi and consequences to our society have been understudied despite evidence showing that pathogenic fungi increase in abundance under global climate change. Moreover, there is a growing concern that global climate change will contribute to the emergence of new fungal pathogens. Yet, we do not understand what mechanisms might be driving this increase in virulence and the onset of pathogenicity. In this study, we investigate how fungi respond to global change drivers, physical disturbance, and drought, in a dryland ecosystem in terms of pathogenicity and stress. We find that indeed, under global change drivers, there is an increase in the transcription and expression of genes associated to pathogenicity and stress, but that microclimatic conditions matter. Our study shows the importance of investigating dryland fungi exposed to global climate change and impacts on our society, which may include threats to public health and food security.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142546507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unraveling the role of cAMP signaling in <i>Giardia</i>: insights into PKA-mediated regulation of encystation and subcellular interactions.","authors":"Han-Wei Shih, Germain C M Alas, Alexander R Paredez","doi":"10.1128/msphere.00723-24","DOIUrl":"https://doi.org/10.1128/msphere.00723-24","url":null,"abstract":"<p><p>cAMP plays an important role as a second messenger in the stage transition of various protozoan parasites. This signaling pathway relies on multiple effectors, such as protein kinase A (PKA), exchange protein activated by cAMP, and cAMP-response element binding protein transcription factors, to initiate signal transduction in humans. The <i>Giardia</i> genome only contains two adenylate cyclases (ACs), a single phosphodiesterase (PDE) and a single known PKA effector, and the specific functions of these components are not fully understood. In our previous research, we demonstrated the important role of AC2-dependent cAMP signaling in promoting the encystation program. Using the NanoBit technology, we emphasized the significance of AC2-dependent cAMP biosynthesis in regulating the dissociation of the PKA regulatory domain (PKAr) and PKA catalytic domain (PKAc). In this study, our objectives are twofold: first, we used the newly developed Split-Halo to examine subcellular interactions of <i>Gl</i>PKAr and <i>Gl</i>PKAc in <i>Giardia</i>; and second, we investigated whether PKAc regulates encystation-specific proteins. Our findings revealed distinct subcellular locations where <i>Gl</i>PKAr and <i>Gl</i>PKAc interacted during the trophozoite stage, including the flagella, basal bodies, and cytoplasm. Upon exposure to encystation stimuli, the interaction shifted from the flagella to the cytosol. Knockdown of <i>Gl</i>PKAc resulted in the downregulation of encystation-specific genes, leading to the production of fewer viable and water-resistant cysts indicating a role for PKA in the transcriptional regulation of encystation. These discoveries contribute to a deeper understanding of the cAMP signaling pathway and its important role in governing <i>Giardia</i>'s encystation process.</p><p><strong>Importance: </strong>The precise timing of interactions and subcellular compartmentation play crucial roles in signal transduction. The co-immunoprecipitation assay (CO-IP) has long been utilized to validate protein-protein interactions; however, CO-IPs lack spatial and temporal resolutions. Our recent study used the NanoBit assay, which showcased the reversible protein-protein interaction between PKAr and PKAc in response to cAMP analogs and encystation stimuli. Expanding on this groundwork, this study employs the Split-Halo assay to uncover the subcellular compartments where the PKAr and PKAc protein-protein interactions take place and respond to encystation stimuli. Taken together, these molecular tools provide spatiotemporal information on the protein-protein interaction, which will be useful in the field.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142546511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring the tolerable region for HiBiT tag insertion in the hepatitis B virus genome.","authors":"Asako Murayama, Hitomi Igarashi, Norie Yamada, Hussein Hassan Aly, Masaaki Toyama, Masanori Isogawa, Tetsuro Shimakami, Takanobu Kato","doi":"10.1128/msphere.00518-24","DOIUrl":"10.1128/msphere.00518-24","url":null,"abstract":"<p><p>A cell culture system that allows the reproduction of the hepatitis B virus (HBV) life cycle is indispensable to exploring novel anti-HBV agents. To establish the screening system for anti-HBV agents, we exploited the high affinity and bright luminescence (HiBiT) tag and comprehensively explored the regions in the HBV genome where the HiBiT tag could be inserted. The plasmids for the HiBiT-tagged HBV molecular clones with a 1.38-fold HBV genome length were prepared. The HiBiT tag was inserted into five regions: preS1, preS2, hepatitis B e (HBe), hepatitis B X (HBx), and hepatitis B polymerase (HB pol). HiBiT-tagged HBVs were obtained by transfecting the prepared plasmids into sodium taurocholate cotransporting polypeptide-transduced HepG2 (HepG2/NTCP) cells, and their infectivity was evaluated in human primary hepatocytes and HepG2/NTCP cells. Among the evaluated viruses, the infection of HiBiT-tagged HBVs in the preS1 or the HB pol regions exhibited a time-dependent increase of the hepatitis B surface antigen (HBsAg) level after infection to HepG2/NTCP cells as well as human primary hepatocytes. Immunostaining of the hepatitis B core (HBc) antigen in infected cells confirmed these viruses are infectious to those cells. However, the time-dependent increase of the HiBiT signal was only detected after infection with the HiBiT-tagged HBV in the preS1 region. The inhibition of this HiBiT-tagged HBV infection in human primary hepatocytes and HepG2/NTCP cells by the preS1 peptide could be detected by measuring the HiBiT signal. The infection system with the HiBiT-tagged HBV in HepG2/NTCP cells facilitates easy, sensitive, and high-throughput screening of anti-HBV agents and will be a useful tool for assessing the viral life cycle and exploring antiviral agents.</p><p><strong>Importance: </strong>Hepatitis B virus (HBV) is the principal causative agent of chronic hepatitis. Despite the availability of vaccines in many countries, HBV infection has spread worldwide and caused chronic infection. In chronic hepatitis B patients, liver inflammation leads to cirrhosis, and the accumulation of viral genome integration into host chromosomes leads to the development of hepatocellular carcinoma. The currently available treatment strategy cannot expect the eradication of HBV. To explore novel anti-HBV agents, a cell culture system that can detect HBV infection easily is indispensable. In this study, we examined the regions in the HBV genome where the high affinity and bright luminescence (HiBiT) tag could be inserted and established an HBV infection system to monitor infection by measuring the HiBiT signal by infecting the HiBiT-tagged HBV in sodium taurocholate cotransporting polypeptide-transduced HepG2 (HepG2/NTCP) cells. This system can contribute to screening for novel anti-HBV agents.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11520284/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142350727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adhesion of <i>Crithidia fasciculata</i> promotes a rapid change in developmental fate driven by cAMP signaling.","authors":"Shane Denecke, Madeline F Malfara, Kelly R Hodges, Nikki A Holmes, Andre R Williams, Julia H Gallagher-Teske, Julia M Pascarella, Abigail M Daniels, Geert Jan Sterk, Rob Leurs, Gordon Ruthel, Rachel Hoang, Megan L Povelones, Michael Povelones","doi":"10.1128/msphere.00617-24","DOIUrl":"10.1128/msphere.00617-24","url":null,"abstract":"<p><p>Trypanosomatids are single-celled parasites responsible for human and animal disease. Typically, colonization of an insect host is required for transmission. Stable attachment of parasites to insect tissues <i>via</i> their single flagellum coincides with differentiation and morphological changes. Although attachment is a conserved stage in trypanosomatid life cycles, the molecular mechanisms are not well understood. To study this process, we elaborate upon an <i>in vitro</i> model in which the swimming form of the trypanosomatid <i>Crithidia fasciculata</i> rapidly differentiates following adhesion to artificial substrates. Live imaging of cells transitioning from swimming to attached shows parasites undergoing a defined sequence of events, including an initial adhesion near the base of the flagellum immediately followed by flagellar shortening, cell rounding, and the formation of a hemidesmosome-like attachment plaque between the tip of the shortened flagellum and the substrate. Quantitative proteomics of swimming versus attached parasites suggests differential regulation of cyclic adenosine monophosphate (cAMP)-based signaling proteins. We have localized two of these proteins to the flagellum of swimming <i>C. fasciculata</i>; however, both are absent from the shortened flagellum of attached cells. Pharmacological inhibition of cAMP phosphodiesterases increased cAMP levels in the cell and prevented attachment. Further, treatment with inhibitor did not affect the growth rate of either swimming or established attached cells, indicating that its effect is limited to a critical window during the early stages of adhesion. These data suggest that cAMP signaling is required for attachment of <i>C. fasciculata</i> and that flagellar signaling domains may be reorganized during differentiation and attachment.IMPORTANCETrypanosomatid parasites cause significant disease burden worldwide and require insect vectors for transmission. In the insect, parasites attach to tissues, sometimes dividing as attached cells or producing motile, infectious forms. The significance and cellular mechanisms of attachment are relatively unexplored. Here, we exploit a model trypanosomatid that attaches robustly to artificial surfaces to better understand this process. This attachment recapitulates that observed <i>in vivo</i> and can be used to define the stages and morphological features of attachment as well as conditions that impact attachment efficiency. We have identified proteins that are enriched in either swimming or attached parasites, supporting a role for the cyclic AMP signaling pathway in the transition from swimming to attached. As this pathway has already been implicated in environmental sensing and developmental transitions in trypanosomatids, our data provide new insights into activities required for parasite survival in their insect hosts.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11520290/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142308182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>Pseudomonas aeruginosa</i> kills <i>Staphylococcus aureus</i> in a polyphosphate-dependent manner.","authors":"Ritika Shah, Julius Kwesi Narh, Magdalena Urlaub, Olivia Jankiewicz, Colton Johnson, Barry Livingston, Jan-Ulrik Dahl","doi":"10.1128/msphere.00686-24","DOIUrl":"10.1128/msphere.00686-24","url":null,"abstract":"<p><p>Due to their frequent coexistence in many polymicrobial infections, including in patients with cystic fibrosis or burn/chronic wounds, many studies have investigated the mechanistic details of the interaction between the opportunistic pathogens <i>Pseudomonas aeruginosa</i> and <i>Staphylococcus aureus. P. aeruginosa</i> rapidly outcompetes <i>S. aureus</i> under <i>in vitro</i> cocultivation conditions<i>,</i> which is mediated by several of <i>P. aeruginosa</i>'s virulence factors. Here, we report that polyphosphate (polyP), an efficient stress defense system and virulence factor in <i>P. aeruginosa</i>, plays a role in the pathogen's ability to inhibit and kill <i>S. aureus</i> in a contact-independent manner. We show that <i>P. aeruginosa</i> cells characterized by low polyP levels are less detrimental to <i>S. aureus</i> growth and survival while the Gram-positive pathogen is significantly more compromised by the presence of <i>P. aeruginosa</i> cells that produce high levels of polyP. The polyP-dependent phenotype of <i>P. aeruginosa</i>-mediated killing of <i>S. aureus</i> could at least in part be direct, as polyP was detected in the spent media and causes significant damage to the <i>S. aureus</i> cell envelope. However, more likely is that polyP's effects are indirect through modulating the production of one of <i>P. aeruginosa's</i> virulence factors, pyocyanin. We show that pyocyanin production in <i>P. aeruginosa</i> occurs polyP-dependently and harms <i>S. aureus</i> through membrane damage and potentially the generation of reactive oxygen species, resulting in the increased expression of antioxidant enzymes. In summary, our study adds a new component to the list of biomolecules that the Gram-negative pathogen <i>P. aeruginosa</i> generates to compete with <i>S. aureus</i> for resources.IMPORTANCEHow do interactions between microorganisms shape the course of polymicrobial infections? Previous studies have provided evidence that the two opportunistic pathogens <i>Pseudomonas aeruginosa</i> and <i>Staphylococcus aureus</i> generate molecules that modulate their interaction with potentially significant impact on disease outcomes. Our study identified the biopolymer polyphosphate (polyP) as a new effector molecule that impacts <i>P. aeruginosa</i>'s interaction with <i>S. aureus</i>. We show that <i>P. aeruginosa</i> kills <i>S. aureus</i> in a polyP-dependent manner, which occurs primarily through the polyP-dependent production of the <i>P. aeruginosa</i> virulence factor pyocyanin. Our findings add a new role for polyP to an already extensive list of functions. A more in-depth understanding of how polyP influences interspecies interactions is critical, as targeting polyP synthesis in bacteria such as <i>P. aeruginosa</i> may have a significant impact on other microorganisms and potentially result in dynamic changes in the microbial composition.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11520310/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142372367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sialic acid and PirB are not required for targeting of neural circuits by neurotropic mammalian orthoreovirus.","authors":"Kira A Griswold, Iaroslavna Vasylieva, Megan C Smith, Kay L Fiske, Olivia L Welsh, Alexa N Roth, Alan M Watson, Simon C Watkins, Danica M Sutherland, Terence S Dermody","doi":"10.1128/msphere.00629-24","DOIUrl":"10.1128/msphere.00629-24","url":null,"abstract":"<p><p>Serotype 3 (T3) strains of mammalian orthoreovirus (reovirus) spread to the central nervous system to infect the brain and cause lethal encephalitis in newborn mice. Although reovirus targets several regions in the brain, susceptibility to infection is not uniformly distributed. The neuronal subtypes and anatomic sites targeted throughout the brain are not precisely known. Reovirus binds several attachment factors and entry receptors, including sialic acid (SA)-containing glycans and paired immunoglobulin-like receptor B (PirB). While these receptors are not required for infection of some types of neurons, reovirus engagement of these receptors can influence neuronal infection in certain contexts. To identify patterns of T3 neurotropism, we used microbial identification after passive tissue clearance and hybridization chain reaction to stain reovirus-infected cells throughout intact, optically transparent brains of newborn mice. Three-dimensional reconstructions revealed in detail the sites targeted by reovirus throughout the brain volume, including dense infection of the midbrain and hindbrain. Using reovirus mutants incapable of binding SA and mice lacking PirB expression, we found that neither SA nor PirB is required for the infection of various brain regions. However, SA may confer minor differences in infection that vary by region. Collectively, these studies indicate that many regions in the brain of newborn mice are susceptible to reovirus and that patterns of reovirus infection are not dependent on reovirus receptors SA and PirB.IMPORTANCENeurotropic viruses invade the central nervous system (CNS) and target various cell types to cause disease manifestations, such as meningitis, myelitis, or encephalitis. Infections of the CNS are often difficult to treat and can lead to lasting sequelae or death. Mammalian orthoreovirus (reovirus) causes age-dependent lethal encephalitis in many young mammals. Reovirus infects neurons in several different regions of the brain. However, the complete pattern of CNS infection is not understood. We found that reovirus targets almost all regions of the brain and that patterns of tropism are not dependent on receptors sialic acid and paired immunoglobulin-like receptor B. These studies confirm that two known reovirus receptors do not completely explain the cell types infected in brain tissue and establish strategies that can be used to understand complete patterns of viral tropism in an intact brain.</p>","PeriodicalId":19052,"journal":{"name":"mSphere","volume":null,"pages":null},"PeriodicalIF":3.7,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11540169/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142350730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}