As in other organisms, CRISPR/Cas9 methods provide a powerful approach for genome editing in the nematode Caenorhabditis elegans. Oligonucleotides are excellent repair templates for introducing ...substitutions and short insertions, as they are cost effective, require no cloning, and appear in other organisms to target changes by homologous recombination at DNA double-strand breaks (DSBs). Here, I describe a methodology in C. elegans to efficiently knock in epitope tags in 8-9 days, using a temperature-sensitive lethal mutation in the pha-1 gene as a co-conversion marker. I demonstrate that 60mer oligos with 29 bp of homology drive efficient knock-in of point mutations, and that disabling nonhomologous end joining by RNAi inactivation of the cku-80 gene significantly improves knock-in efficiency. Homology arms of 35-80 bp are sufficient for efficient editing and DSBs up to 54 bp away from the insertion site produced knock-ins. These findings will likely be applicable for a range of genome editing approaches in C. elegans, which will improve editing efficiency and minimize screening efforts.
Acute and chronic sports-related traumatic brain injuries (TBIs) are a substantial public health concern. Various types of acute TBI can occur in sport, but detection and management of cerebral ...concussion is of greatest importance as mismanagement of this syndrome can lead to persistent or chronic postconcussion syndrome (CPCS) or diffuse cerebral swelling. Chronic TBI encompasses a spectrum of disorders that are associated with long-term consequences of brain injury, including chronic traumatic encephalopathy (CTE), dementia pugilistica, post-traumatic parkinsonism, post-traumatic dementia and CPCS. CTE is the prototype of chronic TBI, but can only be definitively diagnosed at autopsy as no reliable biomarkers of this disorder are available. Whether CTE shares neuropathological features with CPCS is unknown. Evidence suggests that participation in contact-collision sports may increase the risk of neurodegenerative disorders such as Alzheimer disease, but the data are conflicting. In this Review, the spectrum of acute and chronic sport-related TBI is discussed, highlighting how examination of athletes involved in high-impact sports has advanced our understanding of pathology of brain injury and enabled improvements in detection and diagnosis of sport-related TBI.
The airway epithelium protects us from environmental insults, which we encounter with every breath. Not only does it passively filter large particles, it also senses potential danger and alerts other ...cells, including immune and nervous cells. Together, these tissues orchestrate the most appropriate response, balancing the need to eliminate the danger with the risk of damage to the host. Each cell subset within the airway epithelium plays its part, and when impaired, may contribute to the development of respiratory disease. Here we highlight recent advances regarding the cellular and functional heterogeneity along the airway epithelium and discuss how we can use this knowledge to design more effective, targeted therapeutics.
Every year, millions of Americans visit planetariums and are captivated by their strikingly realistic portrayal of the night sky. Today, it is indeed difficult to imagine astronomy education without ...these magnificent celestial theaters. But projection planetariums, first developed in Germany, have been a part of American museum pedagogy only since the early twentieth century and were not widespread until the 1960s. In this unique social history, former planetarium director and historian of science Jordan D. Marché II offers the first complete account of the community of individuals and institutions that, during the period between 1930 and 1970, made planetariums the popular teaching aids they are today. Marché addresses issues such as the role of gender and social developments within the planetarium community, institutional patronage, and the popularization of science. He reveals how, at different times, various groups, including financial donors, amateur scientists, and government officials, viewed the planetarium as an instrument through which they could shape public understanding and perceptions of astronomy and space science. Offering an insightful, wide-ranging look into the origins of an institution that has fascinated millions,Theaters of Time
and Spacebrings new perspectives to how one educational community changed the cultural complexion of science, helped shape public attitudes toward the U.S. space program, and even contributed to policy decisions regarding allocations for future space research.
Experimental manipulation of protein abundance in living cells or organisms is an essential strategy for investigation of biological regulatory mechanisms. Whereas powerful techniques for protein ...expression have been developed in Caenorhabditis elegans, existing tools for conditional disruption of protein function are far more limited. To address this, we have adapted the auxin-inducible degradation (AID) system discovered in plants to enable conditional protein depletion in C. elegans. We report that expression of a modified Arabidopsis TIR1 F-box protein mediates robust auxin-dependent depletion of degron-tagged targets. We document the effectiveness of this system for depletion of nuclear and cytoplasmic proteins in diverse somatic and germline tissues throughout development. Target proteins were depleted in as little as 20-30 min, and their expression could be re-established upon auxin removal. We have engineered strains expressing TIR1 under the control of various promoter and 3' UTR sequences to drive tissue-specific or temporally regulated expression. The degron tag can be efficiently introduced by CRISPR/Cas9-based genome editing. We have harnessed this system to explore the roles of dynamically expressed nuclear hormone receptors in molting, and to analyze meiosis-specific roles for proteins required for germ line proliferation. Together, our results demonstrate that the AID system provides a powerful new tool for spatiotemporal regulation and analysis of protein function in a metazoan model organism.
How to fail at species delimitation Carstens, Bryan C.; Pelletier, Tara A.; Reid, Noah M. ...
Molecular ecology,
September 2013, Letnik:
22, Številka:
17
Journal Article
Recenzirano
Odprti dostop
Species delimitation is the act of identifying species‐level biological diversity. In recent years, the field has witnessed a dramatic increase in the number of methods available for delimiting ...species. However, most recent investigations only utilize a handful (i.e. 2–3) of the available methods, often for unstated reasons. Because the parameter space that is potentially relevant to species delimitation far exceeds the parameterization of any existing method, a given method necessarily makes a number of simplifying assumptions, any one of which could be violated in a particular system. We suggest that researchers should apply a wide range of species delimitation analyses to their data and place their trust in delimitations that are congruent across methods. Incongruence across the results from different methods is evidence of either a difference in the power to detect cryptic lineages across one or more of the approaches used to delimit species and could indicate that assumptions of one or more of the methods have been violated. In either case, the inferences drawn from species delimitation studies should be conservative, for in most contexts it is better to fail to delimit species than it is to falsely delimit entities that do not represent actual evolutionary lineages.
White Over Black Jordan, Winthrop D; Brown, Christopher Leslie; Wood, Peter H
12/2012
eBook
In 1968, Winthrop D. Jordan set out in encyclopedic detail the evolution of white Englishmen's and Anglo-Americans' perceptions of blacks, perceptions of difference used to justify race-based ...slavery, and liberty and justice for whites only. This second edition, with new forewords by historians Christopher Leslie Brown and Peter H. Wood, reminds us that Jordan's text is still the definitive work on the history of race in America in the colonial era. Every book published to this day on slavery and racism builds upon his work; all are judged in comparison to it; none has surpassed it.
Senescence is the consequence of a signaling mechanism activated in stressed cells to prevent proliferation of cells with damage. Senescent cells (Sncs) often develop a senescence-associated ...secretory phenotype to prompt immune clearance, which drives chronic sterile inflammation and plays a causal role in aging and age-related diseases. Sncs accumulate with age and at anatomical sites of disease. Thus, they are regarded as a logical therapeutic target. Senotherapeutics are a new class of drugs that selectively kill Sncs (senolytics) or suppress their disease-causing phenotypes (senomorphics senostatics). Since 2015, several senolytics went from identification to clinical trial. Preclinical data indicate that senolytics alleviate disease in numerous organs, improve physical function and resilience, and suppress all causes of mortality, even if administered to the aged. Here, we review the evidence that Sncs drive aging and disease, the approaches to identify and optimize senotherapeutics, and the current status of preclinical and clinical testing of senolytics.
PDF
