Biology subjects

Diaz, M.

Publications and source records attributed to Diaz, M..

4 recordsLinked to original sources

bioRxiv2018

Stress alters social behavior and sensitivity to pharmacological activation of kappa opioid receptors in an age-specific manner in Sprague Dawley rats

The dynorphin/kappa (DYN/KOR) system has been identified as a primary target of stress due to behavioral effects, such as dysphoria, aversion, and anxiety-like alterations that result from activation of this system. Numerous adaptations in the DYN/KOR system have also been identified in response to stress. However, whereas most studies examining the function of the DYN/KOR system have been conducted in adults, there is growing evidence suggesting that this system is ontogenetically regulated. Likewise, the outcome of exposure to stress also differs across ontogeny. Based on these developmental similarities, the objective of this study was to systematically test effects of a selective KOR agonist, U62066, on various aspects of social behavior across ontogeny in non-stressed male and female rats as well as in males and females with a prior history of repeated exposure to restraint (90 min/day, 5 exposures). We found that the social consequences of repeated restraint differed as a function of age: juvenile stress produced substantial increases in play fighting, whereas adolescent and adult stress resulted in decreases in social investigation and social preference. The KOR agonist U62066 dose-dependently reduced social behaviors in non-stressed adults, producing social avoidance at the highest dose tested, while younger animals displayed reduced sensitivity to this socially suppressing effect of U62066. Interestingly, in stressed animals, the socially suppressing effects of the KOR agonist were blunted at all ages, with juveniles and adolescents exhibiting increased social preference in response to certain doses of U62066. Taken together, these findings support the hypothesis that the DYN/KOR system changes with age and differentially responds and adapts to stress across development.

neuroscience↗

bioRxiv2018

RsmV a small non-coding regulatory RNA in Pseudomonas aeruginosa that sequesters RsmA and RsmF from target mRNAs

The Gram-negative opportunistic pathogen Pseudomonas aeruginosa has distinct genetic programs that favor either acute or chronic virulence gene expression. Acute virulence is associated with twitching and swimming motility, expression of a type III secretion system (T3SS), and the absence of alginate, Psl, or Pel polysaccharide production. Traits associated with chronic infection include growth as a biofilm, reduced motility, and expression of a type VI secretion system (T6SS). The Rsm post-transcriptional regulatory system plays an important role in the inverse control of phenotypes associated with acute and chronic virulence. RsmA and RsmF are RNA-binding proteins that interact with target mRNAs to control gene expression at the post-transcriptional level. Previous work found that RsmA activity is controlled by at least three small, non-coding regulatory RNAs (RsmW, RsmY, and RsmZ). In this study, we took an in-silico approach to identify additional sRNAs that might function in the sequestration of RsmA and/or RsmF and identified RsmV, a 192 nt transcript with four predicted RsmA/RsmF consensus binding sites. RsmV is capable of sequestering RsmA and RsmF in vivo to activate translation of tssA1, a component of the T6SS, and to inhibit T3SS gene expression. Each of the predicted RsmA/RsmF consensus binding sites contribute to RsmV activity. Electrophoretic mobility shifts assays show that RsmF binds RsmV with >10-fold higher affinity than RsmY and RsmZ. Gene expression studies revealed that the temporal expression pattern of RsmV differs from RsmW, RsmY, and RsmZ. These findings suggest that each sRNA may play distinct roles in controlling RsmA and RsmF activity.\n\nIMPORTANCEThe role of RsmF in post-transcriptional control of gene expression remains enigmatic. While numerous rsmA-dependent phenotypes are more pronounced in an rsmAF double mutant, deletion of rsmF alone has only modest effects. Understanding mechanisms that control RsmF activity will provide insight into additional roles for RsmF. In the current study we identify RsmV as an sRNA that controls RsmA and RsmF activity, and show that RsmV, RsmW, RsmY, and RsmZ are differentially expressed during growth.

microbiology↗

bioRxiv2017

Interactive Biology Cloud Lab Enables Authentic Inquiry-Based Science Learning At MOOC Scale

The Next Generation Science Standards (NGSS) and other national frameworks are calling for much more sophisticated approaches to STEM education, centered around the integration of complex experimentation (including real labs, not just simulations), data collection and analysis, modeling, and data-driven argumentation, i.e., students can behave like real scientists. How to implement such complex approaches in scalable ways is an unsolved challenge - both for presential and distance education. Here we report on the iterative design and large-scale deployment of an open online course with a \"biology cloud experimentation lab\" (using living cells) that engaged remote learners (> 300 students) in the scientific practices of experimentation, modeling and data analysis to investigate the phototaxis of a microorganism. We demonstrate (1) the robustness and scalability of the cloud lab technology (> 2, 300 experiments run), (2) the design principles and synergistic integration of multiple UI and learning activities and suitable data formats to facilitate NGSS-aligned science activities, and (3) design features that leverages the natural variability of real biology experiments to instigate authentic inquiry. This platform and course content are now suited for large-scale adaptation in formal K-16 education; and we provide recommendations for inquiry-based science learning in general.

scientific communication and education↗

bioRxiv2017

Age-Related Differences In The Influence Of Task-Irrelevant Information On The Neural Bases Of Phonological And Semantic Processes

Although aging is often associated with cognitive decline, there is considerable variability among individuals and across domains of cognition. Within language, several indicators of semantic processing show stability throughout the lifespan. However, older adults have increased difficulty with phonological aspects of language, especially in language production. While these behavioral patterns are established, the neurobiology associated with these behaviors are less clear. Previously we have shown that, older adults were slower and less accurate in phonological compared to semantic decisions, and that older adults didnt exhibit brain-behavior relationships. In the present study, we examined phonological and semantic processes in the presence of task-irrelevant information. Older and younger adults made phonological and semantic decisions about pictures in the presence of either phonologically-related or semantically-related words, which were unrelated to the task. Behavioral results indicated that overall older adults had slower reaction times and lower accuracy compared to younger adults, and that all adults were less efficient when making phonological compared to semantic decisions. Patterns of brain activation for the semantic condition showed that all adults engaged typical left-hemisphere language regions, and that this activation was positively correlated with efficiency. In contrast, the phonological condition elicited activation in bilateral precuneus and cingulate, but only younger adults showed a significant relationship between activation and efficiency. Our results suggest that the relationship between behavior and neural activation when processing phonological information declines with age, but that the core semantic system continues to be engaged throughout the lifespan, even in the presence of task-irrelevant information.

neuroscience↗