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Li L, Maclntyre LW, Brady SF
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Refactoring biosynthetic gene clusters for heterologous production of microbial natural products (opens in new window)

CURRENT OPINION IN BIOTECHNOLOGY 2021 JUN; 69(?):145-152
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Microbial natural products (NPs) are of paramount importance in human medicine, animal health and plant crop protection. Large-scale microbial genome and metagenomic mining has revealed tremendous biosynthetic potential to produce new NPs. However a majority of NP biosynthetic gene clusters (BGCs) are functionally inaccessible under standard laboratory conditions. BGC refactoring and heterologous expression provide a promising synthetic biology approach to NP discovery, yield optimization and combinatorial biosynthesis studies. In this review, we summarize the recent advances pertaining to the heterologous production of bacterial and fungal NPs, with an emphasis on next-generation transcriptional regulatory modules, novel BGC refactoring techniques and optimized heterologous hosts.
Sanchez-Rivera FJ, Ryan J, Soto-Feliciano YM, Beytagh MC, Xuan L, Feldser DM, Hemann MT, Zamudio J, Dimitrova N, Letai A, Jacks T
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Mitochondrial apoptotic priming is a key determinant of cell fate upon p53 restoration (opens in new window)

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 2021 JUN 8; 118(23):? Article e2019740118
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Reactivation of p53 in established tumors typically results in one of two cell fates, cell cycle arrest or apoptosis, but it remains unclear how this cell fate is determined. We hypothesized that high mitochondrial priming prior to p53 reactivation would lead to apoptosis, while low priming would lead to survival and cell cycle arrest. Using a panel of Kras-driven, p53 restorable cell lines derived from genetically engineered mouse models of lung adenocarcinoma and sarcoma (both of which undergo cell cycle arrest upon p53 restoration), as well as lymphoma (which instead undergo apoptosis), we show that the level of mitochondrial apoptotic priming is a critical determinant of p53 reactivation outcome. Cells with high initial priming (e.g., lymphomas) lacked sufficient reserve antiapoptotic capacity and underwent apoptosis after p53 restoration. Forced BCL-2 or BCL-XL expression reduced priming and resulted in survival and cell cycle arrest. Cells with low initial priming (e.g., lung adenocarcinoma and sarcoma) survived and proceeded to arrest in the cell cycle. When primed by inhibition of their antiapoptotic proteins using genetic (BCL-2 or BCL-XL deletion or BAD overexpression) or pharmacologic (navitoclax) means, apoptosis resulted upon p53 restoration in vitro and in vivo. These data demonstrate that mitochondrial apoptotic priming is a key determining factor of cell fate upon p53 activation. Moreover, it is possible to enforce apoptotic cell fate following p53 activation in less primed cells using p53-independent drugs that increase apoptotic priming, including BH3 mimetic drugs.
Xu J, Zhao XL, Mao FBA, Basrur V, Ueberheide B, Chait BT, Allis CD, Taverna SD, Gao S, Wang W, Liu YF
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A Polycomb repressive complex is required for RNAi-mediated heterochromatin formation and dynamic distribution of nuclear bodies (opens in new window)

NUCLEIC ACIDS RESEARCH 2021 JUN 4; 49(10):5407-5425
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Polycomb group (PcG) proteins are widely utilized for transcriptional repression in eukaryotes. Here, we characterize, in the protist Tetrahymena thermophila, the EZL1 (E(z)-like 1) complex, with components conserved in metazoan Polycomb Repressive Complexes 1 and 2 (PRC1 and PRC2). The EZL1 complex is required for histone H3 K27 and K9 methylation, heterochromatin formation, transposable element control, and programmed genome rearrangement. The EZL1 complex interacts with EMA1, a helicase required for RNA interference (RNAi). This interaction is implicated in co-transcriptional recruitment of the EZL1 complex. Binding of H3K27 and H3K9 methylation by PDD1-another PcG protein interacting with the EZL1 complex-reinforces its chromatin association. The EZL1 complex is an integral part of Polycomb bodies, which exhibit dynamic distribution in Tetrahymena development: Their dispersion is driven by chromatin association, while their coalescence by PDD1, likely via phase separation. Our results provide a molecular mechanism connecting RNAi and Polycomb repression, which coordinately regulate nuclear bodies and reorganize the genome.
Thaler DS, Sakmar TP
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Archiving time series sewage samples as biological records of built environments (opens in new window)

BMC INFECTIOUS DISEASES 2021 JUN 24; 21(1):? Article 601
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This commentary encourages the regular archiving of nucleic-acid-stabilized serial samples of wastewaters and/or sewage. Stabilized samples would facilitate retrospective reconstitution of built environments' biological fluids. Biological time capsules would allow retrospective searches for nucleic acids from viruses such as SARS-CoV-2. Current resources for testing need not be diverted if samples are saved in case they become important in the future. Systematic storage would facilitate investigation into the origin and prevalence of viruses and other agents. Comparison of prevalence data from individual and clinical samplings with community wastewater would allow valuable comparison, contrast and correlation among different testing modalities. Current interest is focused on SARS-CoV-2, but archived samples could become valuable in many contexts including surveys for other infectious and chemical agents whose identity is not currently known. Archived time series of wastewater will take their place alongside other biological repositories and records including those from medical facilities, museums, eDNA, living cell and tissue collections. Together these will prove invaluable records of the evolving Anthropocene.
Ibarlucea-Benitez I, Weitzenfeld P, Smith P, Ravetch JV
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Siglecs-7/9 function as inhibitory immune checkpoints in vivo and can be targeted to enhance therapeutic antitumor immunity (opens in new window)

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 2021 JUN 29; 118(26):? Article e2107424118
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Given the role of myeloid cells in T cell activation and in the antitumor response, targeting checkpoint molecules expressed on this population represents a promising strategy to augment antitumor immunity. However, myeloid checkpoints that can be effectively used as immunotherapy targets are still lacking. Here, we demonstrate the therapeutic potential of targeting the myeloid receptors Siglec-7 and Siglec9 in vivo. By using a humanized immunocompetent murine model, we demonstrate that human Siglec-7 and Siglec-9, in addition to the murine homolog Siglec-E, inhibit the endogenous antitumor immune response, as well as the response to tumor-targeting and immune checkpoint inhibiting antibodies in vivo. The impact of these Siglecs on tumor progression is highly dependent on the anatomical distribution of the tumor and, as a consequence, the local tumor microenvironment, as tumors with a more immune-suppressive tumor microenvironment are less sensitive to Siglec perturbation. Finally, to assess the potential of these two receptors as targets for immunotherapy, we developed Fc engineered blocking antibodies to Siglec-7 and Siglec-9 and demonstrate that Siglec-7 and Siglec-9 blockade can significantly reduce tumor burden in vivo, demonstrating the therapeutic potential of targeting these two receptors.
Gultekin YB, Hildebrand DGC, Hammerschmidt K, Hage SR
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High plasticity in marmoset monkey vocal development from infancy to adulthood (opens in new window)

SCIENCE ADVANCES 2021 JUN; 7(27):? Article eabf2938
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The vocal behavior of human infants undergoes marked changes across their first year while becoming increasingly speech-like. Conversely, vocal development in nonhuman primates has been assumed to be largely predetermined and completed within the first postnatal months. Contradicting this assumption, we found a dichotomy between the development of call features and vocal sequences in marmoset monkeys, suggestive of a role for experience. While changes in call features were related to physical maturation, sequences of and transitions between calls remained flexible until adulthood. As in humans, marmoset vocal behavior developed in stages correlated with motor and social development stages. These findings are evidence for a prolonged phase of plasticity during marmoset vocal development, a crucial primate evolutionary preadaptation for the emergence of vocal learning and speech.
Goodroe A, Wachtman L, Benedict W, Allen-Worthington K, Bakker J, Burns M, Diaz LL, Dick E, Dickerson M, Eliades SJ, Gonzalez O, Graf DJ, Haroush K, Inoue T, Izzi J, Laudano A, Layne-Colon D, Leblanc M, Ludwig B, Mejia A, Miller C, Sarfaty A, Sosa M, Vallender E, Brown C, Forney L, Schultz-Darken N, Colman R, Power M, Capuano S, Ross C, Tardif S
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Current practices in nutrition management and disease incidence of common marmosets (Callithrix jacchus) (opens in new window)

JOURNAL OF MEDICAL PRIMATOLOGY 2021 JUN; 50(3):164-175
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Background A survey was developed to characterize disease incidence, common pathology lesions, environmental characteristics, and nutrition programs within captive research marmoset colonies. Methods Seventeen research facilities completed the electronic survey. Results Nutritional management programs varied amongst research institutions housing marmosets; eight primary base diets were reported. The most common clinical syndromes reported were gastrointestinal disease (i.e. inflammatory bowel disease like disease, chronic lymphocytic enteritis, chronic malabsorption, chronic diarrhea), metabolic bone disease or fracture, infectious diarrhea, and oral disease (tooth root abscesses, gingivitis, tooth root resorption). The five most common pathology morphologic diagnoses were colitis, nephropathy/nephritis, enteritis, chronic lymphoplasmacytic enteritis, and cholecystitis. Obesity was more common (average 20% of a reporting institution's population) than thin body condition (average 5%). Conclusions Through review of current practices, we aim to inspire development of evidence-based practices to standardize husbandry and nutrition practices for marmoset research colonies.
Nestor PG, Hasler VC, O'Donovan K, Lapp HE, Boodai SB, Hunter R
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Psychiatric risk and resilience: Plasticity genes and positive mental health (opens in new window)

BRAIN AND BEHAVIOR 2021 JUN; 11(6):? Article e02137
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Objective The at-risk mental state (ARMS) for psychosis has long played a key role in diathesis-stress models of schizophrenia. More recent studies, however, have called for extending the boundaries of the ARMS construct beyond attenuated psychosis in nonhelp-seeking samples to include not only other vulnerability indicators but also protective factors related to genotype, mental health, personality, and cognition. Method Accordingly, we assessed in a sample of 100 college students, the ARMS construct with the Brief Prodromal Questionnaire (PQ-B) for psychosis, in conjunction with measures of positive mental health, childhood adversity, psychiatric symptoms, personality traits, social cognition, and genetic variables derived from assays of the serotonin transporter (5-HTTLPR) and the brain-derived neurotrophic factor (BDNF). Results Higher PQ-B scores correlated positively with vulnerability indicators of childhood adversity and heightened levels of a wide variety of psychiatric symptoms but correlated negatively with protective factors of better overall mental health, social cognition as well as with a distinct NEO profile marked by reduced neuroticism and elevated agreeableness and conscientiousness. Multivariate analyses indicated that a composite ARMS measure comprised of PQ-B scores plus anxiety and depression symptoms revealed significant genotype differences, with lowest risk and highest resilience for allelic carriers of 5-HTTLPR-short and BDNF Met polymorphisms. Conclusions Results provided support for extending the ARMS construct, pointing to important contributions of personality, social cognition, and genes that support neural plasticity in mitigating vulnerability and enhancing resilience and well-being.
Lawal OU, Barata M, Fraqueza MJ, Worning P, Bartels MD, Goncalves L, Paixao P, Goncalves E, Toscano C, Empel J, Urbas M, Domiinguez MA, Westh H, de Lencastre H, Miragaia M
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Staphylococcus saprophyticus From Clinical and Environmental Origins Have Distinct Biofilm Composition (opens in new window)

FRONTIERS IN MICROBIOLOGY 2021 JUN 7; 12(?):? Article 663768
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Biofilm formation has been shown to be critical to the success of uropathogens. Although Staphylococcus saprophyticus is a common cause of urinary tract infections, its biofilm production capacity, composition, genetic basis, and origin are poorly understood. We investigated biofilm formation in a large and diverse collection of S. saprophyticus (n = 422). Biofilm matrix composition was assessed in representative strains (n = 63) belonging to two main S. saprophyticus lineages (G and S) recovered from human infection, colonization, and food-related environment using biofilm detachment approach. To identify factors that could be associated with biofilm formation and structure variation, we used a pangenome-wide association study approach. Almost all the isolates (91%; n = 384/422) produced biofilm. Among the 63 representative strains, we identified eight biofilm matrix phenotypes, but the most common were composed of protein or protein-extracellular DNA (eDNA)-polysaccharides (38%, 24/63 each). Biofilms containing protein-eDNA-polysaccharides were linked to lineage G and environmental isolates, whereas protein-based biofilms were produced by lineage S and infection isolates (p < 0.05). Putative biofilm-associated genes, namely, aas, atl, ebpS, uafA, sasF, sasD, sdrH, splE, sdrE, sdrC, sraP, and ica genes, were found with different frequencies (3-100%), but there was no correlation between their presence and biofilm production or matrix types. Notably, icaC_1 was ubiquitous in the collection, while icaR was lineage G-associated, and only four strains carried a complete ica gene cluster (icaADBCR) except one that was without icaR. We provided evidence, using a comparative genomic approach, that the complete icaADBCR cluster was acquired multiple times by S. saprophyticus and originated from other coagulase-negative staphylococci. Overall, the composition of S. saprophyticus biofilms was distinct in environmental and clinical isolates, suggesting that modulation of biofilm structure could be a key step in the pathogenicity of these bacteria. Moreover, biofilm production in S. saprophyticus is ica-independent, and the complete icaADBCR was acquired from other staphylococci.
Durkin SM, Chakraborty M, Abrieux A, Lewald KM, Gadau A, Svetec N, Peng JH, Kopyto M, Langer CB, Chiu JC, Emerson JJ, Zhao L
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Behavioral and Genomic Sensory Adaptations Underlying the Pest Activity of Drosophila suzukii (opens in new window)

MOLECULAR BIOLOGY AND EVOLUTION 2021 JUN; 38(6):2532-2546
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Studying how novel phenotypes originate and evolve is fundamental to the field of evolutionary biology as it allows us to understand how organismal diversity is generated and maintained. However, determining the basis of novel phenotypes is challenging as it involves orchestrated changes at multiple biological levels. Here, we aim to overcome this challenge by using a comparative species framework combining behavioral, gene expression, and genomic analyses to understand the evolutionary novel egg-laying substrate-choice behavior of the invasive pest species Drosophila suzukii. First, we used egg-laying behavioral assays to understand the evolution of ripe fruit oviposition preference in D. suzukii compared with closely related species D. subpulchrella and D. biarmipes as well as D. melanogaster. We show that D. subpulchrella and D. biarmipes lay eggs on both ripe and rotten fruits, suggesting that the transition to ripe fruit preference was gradual. Second, using two-choice oviposition assays, we studied how D. suzukii, D. subpulchrella, D. biarmipes, and D. melanogaster differentially process key sensory cues distinguishing ripe from rotten fruit during egg-laying. We found that D. suzukii's preference for ripe fruit is in part mediated through a species-specific preference for stiff substrates. Last, we sequenced and annotated a high-quality genome for D. subpulchrella. Using comparative genomic approaches, we identified candidate genes involved in D. suzukii's ability to seek out and target ripe fruits. Our results provide detail to the stepwise evolution of pest activity in D. suzukii, indicating important cues used by this species when finding a host, and the molecular mechanisms potentially underlying their adaptation to a new ecological niche.