bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bacterial outer membrane vesicles provide an alternative pathway for trafficking of type III secreted effectors into epithelial cells
Authors: Sirisaengtaksin Natalie , O’Donoghue Eloise J. , Jabbari Sara , Roe Andrew J. , Krachler Anne Marie 
Published: September 2018

ABSTRACTOuter membrane vesicles (OMVs) are proteo-liposomes universally shed by Gram-negative bacteria. Their secretion is significantly enhanced by the transition into the intra-host milieu and OMVs have been shown to play critical roles during pathogenesis. EnterohemorrhagicEscherichia coliO157 (EHEC), causes diarrheal disease in humans, and soluble toxins including Shiga-like toxins that contribute to disease severity and clinical complications including hemolytic uremic syndrome, have been shown to be OMV associated. In addition to Shiga-like toxins, EHEC produces a type III secretion system (T3SS), and T3SS effectors are associated with colonization and disease severityin vivo. Here, we show that type III secreted substrates including translocators and effectors are incorporated into OMVs independent of type III secretion activity. EHEC strains with non-functional type III secretion systems shed more OMVs and vesicles enter host cells with accelerated kinetics compared to vesicles shed from wild type EHEC. The T3SS effector translocated intimin receptor (Tir) is trafficked from OMVs into host cells and localizes to the membrane. However, its clustering on the host membrane and co-localization with bacterial pedestals is intimin-dependent. We further show that OMV-delivered Tir can cross-complement an effector-deficient EHEC strain, demonstrating that OMV-associated effectors reach the host cell in a biologically intact form. Finally, we observe that the non-LEE encoded E3 ubiquitin ligase effector NleL is also trafficked to host cells via OMVs, where it ubiquitinylates its target kinase JNK. Together, these data demonstrate that trafficking of OMV-associated effectors is a novel and T3SS-independent pathway for the delivery of active effectors to host cells.
Calcium-responsive transactivator (CREST) toxicity is rescued by loss of PBP1/ATXN2 function in a novel yeast proteinopathy model and in transgenic flies
Authors: Park By Sangeun , Park Sei-Kyoung , Watanabe Naruaki , Hashimoto Tadafumi , Iwatsubo Takeshi , Shelkovnikova Tatyana A. , Liebman Susan W. 
Published: September 2018

AbstractProteins associated with familial neurodegenerative disease often aggregate in patients’ neurons. Several such proteins, e.g. TDP-43, aggregate and are toxic when expressed in yeast. Deletion of the ATXN2 ortholog,PBP1,reduces yeast TDP-43 toxicity, which led to identification of ATXN2 as an amyotrophic lateral sclerosis (ALS) risk factor and therapeutic target. Likewise, new yeast neurodegenerative disease models could facilitate identification of other risk factors and targets. Mutations inSS18L1,encoding the calcium-responsive transactivator (CREST) chromatin-remodeling protein, are associated with ALS. We show that CREST is toxic in yeast and forms nuclear and occasionally cytoplasmic foci that stain with Thioflavin-T, a dye indicative of amyloid-like protein. Like the yeast chromatin-remodeling factor SWI1, CREST inhibits silencing ofFLOgenes. Toxicity of CREST is enhanced by the [PIN+] prion and reduced by deletion of theHSP104chaperone required for the propagation of many yeast prions. Likewise, deletion ofPBP1reduced CREST toxicity and aggregation. In accord with the yeast data, we show that the Drosophila ortholog of human ATXN2, dAtx2, is a potent enhancer of CREST toxicity. Downregulation of dAtx2 in flies overexpressing CREST in retinal ganglion cells was sufficient to largely rescue the severe degenerative phenotype induced by human CREST. Overexpression caused considerable co-localization of CREST and PBP1/ATXN2 in cytoplasmic foci in both yeast and mammalian cells. Thus, co-aggregation of CREST and PBP1/ATXN2 may serve as one of the mechanisms of PBP1/ATXN2-mediated toxicity. These results extend the spectrum of ALS associated proteins whose toxicity is regulated byPBP1/ATXN2, suggesting that therapies targeting ATXN2 may be effective for a wide range of neurodegenerative diseases.Author summaryMutations in the calcium-responsive transactivator (CREST) protein have been shown to cause amyotrophic lateral sclerosis (ALS). Here we show that the human CREST protein expressed in yeast forms largely nuclear aggregates and is toxic. We also show that the HSP104 chaperone required for propagation of yeast prions is likewise required for CREST toxicity. Furthermore deletion of HSP104 affects CREST aggregation. ATXN2, previously shown to modify ALS toxicity caused by mutations in the TDP-43 encoding gene, also modifies toxicity of CREST expressed in either yeast or flies. In addition, deletion of the yeast ATXN2 ortholog reduces CREST aggregation. These results extend the spectrum of ALS associated proteins whose toxicity is regulated byATXN2, suggesting that therapies targeting ATXN2 may be effective for a wide range of neurodegenerative diseases.
Rapid development of an infant-derived HIV-1 broadly neutralizing antibody lineage
Authors: Simonich Cassandra A , Doepker Laura , Ralph Duncan , Williams James A , Dhar Amrit , Yaffe Zak , Gentles Lauren , Small Christopher T , Oliver Brian , Vigdorovich Vladimir , Prasad Vidya Mangala , Nduati Ruth , Sather D Noah , Lee Kelly K , Frederick A Matsen , Overbaugh Julie 
Published: September 2018

SummaryHIV-infected infants develop broadly neutralizing plasma responses with more rapid kinetics than adults, suggesting the ontogeny of infant responses could better inform a path to achievable vaccine targets. We developed computational methods to reconstruct the developmental lineage of BF520.1, the first example of a HIV-specific broadly neutralizing antibody (bnAb) from an infant. The BF520.1 inferred naïve precursor binds HIV Env and a bnAb evolved within six months of infection and required only 3% mutation. Mutagenesis and structural analyses revealed that for this infant bnAb, substitutions in the kappa chain were critical for activity, particularly in CDRL1. Overall, the developmental pathway of this infant antibody includes features distinct from adult antibodies, including several that may be amenable to better vaccine responses.
Microbial metabolite deoxycholic acid controlsClostridium perfringens-induced chicken necrotic enteritis through attenuating cyclooxygenase signaling
Authors: Wang Hong , Latorre Juan D. , Bansal Mohit , Abraha Mussie , Al-Rubaye Bilal , Tellez Guillermo , Hargis Billy , Sun Xiaolun 
Published: September 2018

AbstractClostridium perfringens-induced necrotic enteritis (NE) has reemerged as a prevalent chicken disease worldwide due to reduced usage of prophylactic antibiotics. The lack of antimicrobial alternative strategies to control NE is mainly due to limited insight into the disease pathogenesis. The aim of this study is to investigate the role of microbiota metabolic product secondary bile acid deoxycholic acid (DCA) on preventing NE.C. perfringensgrowth was inhibited by 82.8% in 50 μM DCA Tryptic Soy Broth. SequentialEimeria maximaandC. perfringenschallenges induced acute NE showed as severe intestinal inflammation and body weight (BW) loss in broiler chickens, while 1.5 g/kg DCA diet dramatically reduced the disease. At the cellular level, DCA alleviated NE-associated ileal epithelial death and reduced lamina propria cell apoptosis. Interestingly, DCA reducedC. perfringensinvasion into ileum without altering the bacterial ileal luminal colonization. Molecular analysis showed that DCA reduced inflammatory mediators ofInfγ,Litaf, andMmp9mRNA accumulation in ileal tissue. Mechanism studies revealed thatC. perfringensinduced elevated expression of inflammatory mediators ofInfγ,Litaf,Mmp9,andPtgs2(Cyclooxygenase- 2 (COX-2) gene) in chicken splenocytes. Blocking COX signaling by pharmacological inhibitor aspirin attenuated INFγ-induced inflammatory response in the splenocytes. Consistent with thein vitroassay, chickens fed 0.12 g/kg aspirin diet protected the birds against NE-induced ileal inflammation, intestinal cell apoptosis, and BW loss. In conclusion, microbial metabolic product DCA prevents NE-induced ileal inflammation and BW loss through attenuating inflammatory response. These novel findings offer new strategies againstC. perfringens-induced diseases.Significance StatementWidespread antimicrobial resistance has become a serious challenge to both agricultural and healthcare industries. Withdrawing antimicrobials without effective alternatives exacerbates chicken productivity loss at billions of dollars every year, caused by intestinal diseases, such as coccidiosis-andC. perfringens-induced necrotic enteritis. This study revealed that microbial metabolic product secondary bile acid DCA preventsC. perfringens-induced intestinal disease in chickens through modulating inflammatory COX signaling pathways. Therefore, microbiome and its downstream targets of host inflammatory responses could be used to control NE. These findings have opened new avenues for developing novel antimicrobial free alternatives to prevent or treatC. perfringens-induced diseases.
RstA is a Major Regulator ofClostridioides difficileToxin Production and Motility
Authors: Edwards Adrianne N. , Anjuwon-Foster Brandon R. , McBride Shonna M. 
Published: September 2018

ABSTRACTClostridioides difficileinfection (CDI) is a toxin-mediated disease. Several factors have been identified that influence the production of the two majorC. difficiletoxins, TcdA and TcdB, but prior published evidence suggested that additional unknown factors were involved in toxin regulation. Previously, we identified aC. difficileregulator, RstA, that promotes sporulation and represses motility and toxin production. We observed that the predicted DNA-binding domain of RstA was required for RstA-dependent repression of toxin genes, motility genes andrstAtranscription. In this study, we further investigated the regulation of toxin and motility gene expression by RstA. DNA pulldown assays confirmed that RstA directly binds therstApromoter via the predicted DNA-binding domain. Through mutational analysis of therstApromoter, we identified several nucleotides that are important for RstA-dependent transcriptional regulation. Further, we observed that RstA directly binds and regulates the promoters of the toxin genes,tcdAandtcdB, as well as the promoters for thesigDandtcdRgenes, which encode regulators of toxin gene expression. Complementation analyses with theClostridium perfringensRstA ortholog and a multi-species chimeric RstA protein revealed that theC. difficileC-terminal domain is required for RstA DNA-binding activity, suggesting that species-specific signaling controls RstA function. Our data demonstrate that RstA is a transcriptional repressor that autoregulates its own expression and directly inhibits transcription of the two toxin genes and two positive toxin regulators, thereby acting at multiple regulatory points to control toxin production.IMPORTANCEClostridioides difficileis an anaerobic, gastrointestinal pathogen of humans and other mammals.C. difficileproduces two major toxins, TcdA and TcdB, which cause the symptoms of the disease, and forms dormant endospores to survive the aerobic environment outside of the host. A recently discovered regulatory factor, RstA, inhibits toxin production and positively influences spore formation. Herein, we determine that RstA directly represses toxin gene expression and gene expression of two toxin gene activators, TcdR and SigD, creating a complex regulatory network to tightly control toxin production. In addition, the ability for RstA to bind DNA and repress toxin production requires the species-specific domain predicted to respond to small quorum-sensing peptides. This study provides a novel regulatory link betweenC. difficilesporulation and toxin production. Further, our data suggest thatC. difficiletoxin production is regulated through a direct sensing mechanism.
Cre-dependent optogenetic transgenic mice without early age-related hearing loss
Authors: Lyngholm Daniel , Sakata Shuzo 
Published: September 2018

AbstractWith the advent of recent genetic technologies for mice, it is now feasible to investigate the circuit mechanisms of brain functions in an unprecedented manner. Although transgenic mice are commonly used on C57BL/6J (C57) background, hearing research has typically relied on different genetic backgrounds, such as CBA/Ca or CBA due to the genetic defect of C57 mice for early age-related hearing loss. This limits the utilization of available genetic resources for hearing research. Here we report congenic (>F10) Cre-dependent channelrhodopsin2 (ChR2) mice on CBA/Ca background. By crossing this line with Cre-driver mice on C57 background, F1 hybrids restored the hearing deficit of C57 mice. We also found a linear relationship between aging and hearing loss, with progression rates varied depending on genetic backgrounds (3.39 dB/month for C57; 0.82 dB/month for F1 hybrid). We further demonstrate that this approach allows to express ChR2 in a specific type of inhibitory neurons in the auditory cortex and that they can be identified within a simultaneously recorded population of neurons in awake mice. Thus, our Cre-dependent optogenetic transgenic mice on CBA/Ca background are a valuable tool to investigate the circuit mechanisms of hearing across lifespan.
Subcellular localization of microcystin in the liver and the gonad of medaka fish acutely exposed to microcystin-LR
Authors: Qiao Qin , Djediat Chakib , Huet Hélène , Duval Charlotte , Manach Séverine Le , Bernard Cécile , Edery Marc , Marie Benjamin 
Published: September 2018

AbstractAmong the diverse toxic components produced by cyanobacteria, microcystins (MCs) are one of the most toxic and notorious cyanotoxin groups. Besides their potent hepatotoxicity, MCs have been revealed to induce potential reproductive toxicity in various animal studies. However, little is still known regarding the distribution of MCs in the reproductive organ, which could directly affect reproductive cells. In order to respond to this question, an acute study was conducted in adult medaka fish (model animal) gavaged with 10 µg.g-1 body weight of pure MC-LR. The histological and immunohistochemical examinations reveal an intense distribution of MC-LR within hepatocytes along with a severe liver lesion in the toxin-treated female and male fish. Besides being accumulated in the hepatocytes, MC-LR was also found in the connective tissue of the ovary and the testis, as well as in oocytes and degenerative spermatocyte-like structures. Both liver and gonad play important roles in the reproductive process of oviparous vertebrates. This observation constitutes the first observation of the presence of MC-LR in the reproductive cell of a vertebrate model with in vivo study. Our results, which provide intracellular localization of MC-LR in the gonad, advance our understanding of the potential reproductive toxicity of MC-LR in fish.
Mapping the Substrate Recognition Pathway in Cytochrome P450
Authors: Ahalawat Navjeet , Mondal Jagannath 
Published: September 2018

AbstractCytochrome P450s are ubiquitous metalloenzymes involved in the metabolism and detoxification of foreign components via catalysis of the hydroxylation reactions of a vast array of organic substrates. However, despite the breadth of cytochrome P450 mediated reactions, a long-standing question is: How does the substrate, in the first place, access the catalytic center of cytochrome P450? The prevalence of conflicting crystallographic evidences of both closed and open catalytic center in the substrate-free and substrate-bound cytochrome P450 has given rise to a notion of conformational heterogeneity, which makes the plausible mechanism of substrate recognition by cytochrome P450 puzzling from structural point of view. Here we report multi-microsecond-long unbiased molecular dynamics simulations, which are able to capture the spontaneous process of binding of substrate from bulk solvent to the occluded catalytic center of an archetypal system cytochrome P450cam, at an atomistic precision. In all binding trajectories, the substrate enters through a single channel, where it makes its first contact with the protein-surface and subsequently dwells in a highly long-lived intermediate state, before sliding into the catalytic center of P450cam. The simulated substrate-bound pose and crystallographic pose are in excellent agreement. Contrary to the prevalent hypotheses, our results indicate that a large-scale opening of F/G loop of P450cam is not required for passage of substrate to the catalytic center. Rather, we find that a substrate-induced side-chain displacement of Phe87 residue, coupled with a complex array of dynamical interconversions of multiple metastable substrate conformations along the entry channel, drives the substrate recognition in P450cam. By reconciling multiple precedent investigations, this work put forward an unambiguous view of the substrate recognition mechanism in deep buried cavity of cytochrome P450.
Effects of exposure to sublethal concentrations of methoxyfenozide on honey bee colony activity and thermoregulation
Authors: Meikle William G. , Corby-Harris Vanessa , Carroll Mark J. , Weiss Milagra , Snyder Lucy A. , Meador Charlotte A.D. , Beren Eli , Brown Nicholas 
Published: September 2018

AbstractMethoxyfenozide is an insect growth regulator (IGR) commonly used in agricultural to simultaneously control pests and preserve beneficial insect populations; however, its impact on honey bees in not fully understood. We conducted field and laboratory experiments to investigate bee health in response to field-relevant doses of this pesticide. Significant effects were observed in honey bee colony flight activity and thermoregulation after being treated with methoxyfenozide. Data collected indicated that hives fed 500 ppb methoxyfenozide treated pollen patty had: 1) a significantly reduced rate of daily hive weight loss due to forager departure at the start of the colony’s daily activity; 2) the end of the colony’s daily activity delayed by 17-21 minutes compared to Control; and 3) higher temperature variability during the winter. Colonies in the 125 ppb treatment group had fewer differences with the Control group, but did show a delay in the foraging end time by 30-46 minutes compared to the Control. Bee colony metrics of adult bee mass and brood surface area, and individual bee measurements of head weight, newly-emerged bee weight, and hypopharyngeal gland size were not significantly affected by the methoxyfenozide exposure levels of our experiments. An experiment conducted using the same treatment groups in the spring resulted in fewer differences among groups than did the experiments conducted in the fall. Analyses of methoxyfenozide concentrations in the treatment patty, wax, and bee bread showed that: 1) observed methoxyfenozide concentrations were about 18-60% lower than the calculated concentrations; 2) no residues were observed in wax in any treatment; and 3) methoxyfenozide was detected in stored bee bread in the 500 ppb treatment, at concentrations about 1-2.5% of the observed concentration for that treatment. These results suggest that there may be significant effects on honey bee colony behavior (and possibly health) in the field that are difficult to detect through traditional hive inspections and individual metrics.
Implementation of a practical and effective control program for Taenia solium in the Banke District of Nepal
Authors: Poudel Ishab , Sah Keshav , Subedi Suyog , Singh Dinesh Kumar , Kushwaha Peetambar , Colston Angela , Gauci Charles G. , Donadeu Meritxell , Lightowlers Marshall W. 
Published: September 2018

AbstractTaenia solium is a zoonotic cestode parasite which causes human neurocysticercosis. Pigs transmit the parasite by acting as the intermediate host. An intervention was implemented in pigs to control transmission of T. solium in Dalit communities of Banke District, Nepal. Every 3 months, pigs were vaccinated with the TSOL18 recombinant vaccine (Cysvax™, IIL, India)) and, at the same time, given an oral treatment with 30mg/kg oxfendazole (Paranthic 10%™, MCI, Morocco). The prevalence of porcine cysticercosis was determined in both an intervention area as well as a similar no intervention control area, among randomly selected, slaughter-age pigs. Post mortem assessments were undertaken both at the start and at the end of the intervention. Participants conducting the post mortem assessments were blinded as to the source of the animals being assessed. At the start of the intervention the prevalence of porcine cysticercosis was 23.6% and 34.5% in the control and intervention areas, respectively. Following the intervention, the prevalence of cysticercosis in pigs from the control area was 16.7% (no significant change), whereas no infection was detected after complete slicing of all muscle tissue and brain in animals from the intervention area (P=0.004). These findings are discussed in relation to the feasibility and sustainability of T. solium control. The 3-monthly vaccination and drug treatment intervention in pigs used here is suggested as an effective and practical method for reducing T. solium transmission, thereby reducing the incidence of human neurocysticercosis.Author summaryNeurocysticercosis is a disease caused by a parasitic infection of the brain. The parasite responsible, Taenia solium, is transmitted by pigs where human sanitation is poor and pigs roam freely. Neurocysticercosis is responsible for many cases of epilepsy in people living in poor, developing countries. The feasibility and sustainability of implementing control measures have been major impediments to reducing the incidence of neurocysticercosis. Recently, two new commercial products have become available for pigs which together offer the possibility of interrupting the parasite’s transmission the TSOL18 vaccine (Cysvax™, IIL, India) and an oxfendazole formulation (Paranthic 10%™, MCI, Morocco) licensed for use in pigs for the treatment of cysticercosis. Here we describe the impact of implementing vaccination plus drug treatment of pigs in the Banke district of Nepal. The intervention eliminated the risk of transmission of T. solium by the animals vaccinated and treated during the trial. Application of the vaccination and drug treatment program used here, possibly with strategic use of anthelmintics also in the human population, is an effective option for reducing the incidence of neurocysticercosis in Nepal and elsewhere.