Meet the author: Laura Amaya.

We talk to first author Laura Amaya about her paper "Pathways for macrophage uptake of cell-free circular RNAs" (in this issue of Molecular Cell), her path to becoming a scientist, and some of the lessons she's learned along the way.

Pathways for macrophage uptake of cell-free circular RNAs.

Circular RNAs (circRNAs) are stable RNAs present in cell-free RNA, which may comprise cellular debris and pathogen genomes. Here, we investigate the phenomenon and mechanism of cellular uptake and intracellular fate of exogenous circRNAs. Human myeloid cells and B cells selectively internalize extracellular circRNAs. Macrophage uptake of circRNA is rapid, energy dependent, and saturable. CircRNA uptake can lead to translation of encoded sequences and antigen presentation. The route of internalization influences immune activation after circRNA uptake, with distinct gene expression programs depending on the route of RNA delivery. Genome-scale CRISPR screens and chemical inhibitor studies nominate macrophage scavenger receptor MSR1, Toll-like receptors, and mTOR signaling as key regulators of receptor-mediated phagocytosis of circRNAs, a dominant pathway to internalize circRNAs in parallel to macropinocytosis. These results suggest that cell-free circRNA serves as an "eat me" signal and danger-associated molecular pattern, indicating orderly pathways of recognition and disposal.

Organ- and Cell-Selective Delivery of mRNA In Vivo Using Guanidinylated Serinol Charge-Altering Releasable Transporters.

Selective RNA delivery is required for the broad implementation of RNA clinical applications, including prophylactic and therapeutic vaccinations, immunotherapies for cancer, and genome editing. Current polyanion delivery relies heavily on cationic amines, while cationic guanidinium systems have received limited attention due in part to their strong polyanion association, which impedes intracellular polyanion release. Here, we disclose a general solution to this problem in which cationic guanidinium groups are used to form stable RNA complexes upon formulation but at physiological pH undergo a novel charge-neutralization process, resulting in RNA release. This new delivery system consists of guanidinylated serinol moieties incorporated into a charge-altering releasable transporter (GSer-CARTs). Significantly, systematic variations in structure and formulation resulted in GSer-CARTs that exhibit highly selective mRNA delivery to the lung (∼97%) and spleen (∼98%) without targeting ligands. Illustrative of their breadth and translational potential, GSer-CARTs deliver circRNA, providing the basis for a cancer vaccination strategy, which in a murine model resulted in antigen-specific immune responses and effective suppression of established tumors.

Epigenetic signature and key transcriptional regulators of human antigen-specific type 1 regulatory T cells.

Human adaptive immunity is orchestrated by effector and regulatory T (Treg) cells. Natural Tregs arise in the thymus where they are shaped to recognize self-antigens, while type 1 Tregs or Tr1 cells are induced from conventional peripheral CD4 + T cells in response to peripheral antigens, such as alloantigens and allergens. Tr1 cells have been developed as a potential therapy for inducing antigen-specific tolerance, because they can be rapidly differentiated in vitro in response to a target antigen. However, the epigenetic landscape and the identity of transcription factors (TFs) that regulate differentiation, phenotype, and functions of human antigen-specific Tr1 cells is largely unknown, hindering Tr1 research and broader clinical development. Here, we reveal the unique epigenetic signature of antigen-specific Tr1 cells, and TFs that regulate their differentiation, phenotype and function. We showed that in vitro induced antigen-specific Tr1 cells are distinct both clonally and transcriptionally from natural Tregs and other conventional CD4 + T cells on a single-cell level. An integrative analysis of Tr1 cell epigenome and transcriptome identified a TF signature unique to antigen-specific Tr1 cells, and predicted that IRF4, BATF, and MAF act as their transcriptional regulators. Using functional genomics, we showed that each of these TFs play a non-redundant role in regulating Tr1 cell differentiation, suppressive function, and expression of co-inhibitory and cytotoxic proteins. By using the Tr1-specific TF signature as a molecular fingerprint, we tracked Tr1 cells in peripheral blood of recipients of allogeneic hematopoietic stem cell transplantation treated with adoptive Tr1 cell therapy. Furthermore, the same signature identified Tr1 cells in resident CD4 + T cells in solid tumors. Altogether, these results reveal the epigenetic signature and the key transcriptional regulators of human Tr1 cells. These data will guide mechanistic studies of human Tr1 cell biology and the development and optimization of adoptive Tr1 cell therapies.

Going with the µFlow: Reinterpreting Energy Input in Organic Synthesis.

The popularity of microflow chemistry has skyrocketed in the last 20 years, more and more chemists are switching from macro-batch reactors to miniaturized flow devices. As a result, microfluidics is paving its way into the future by consolidating its position in organic chemistry not only as a trend but as a new, effective, and sustainable way of conducting chemistry, that clearly will continue to grow and evolve. This perspective highlights the most relevant examples of innovative enhancing technologies applied to microflow reactors aimed to improve and intensify chemical processes. The extensive applicability of microflow chemistry is further illustrated by briefly discussing examples of complex integrated microsystems and scale-up technologies, demonstrating ultimately that microflow chemistry has the potential to become the ideal technology for the future.

Charge-altering releasable transporters enhance mRNA delivery in vitro and exhibit in vivo tropism.

The introduction of more effective and selective mRNA delivery systems is required for the advancement of many emerging biomedical technologies including the development of prophylactic and therapeutic vaccines, immunotherapies for cancer and strategies for genome editing. While polymers and oligomers have served as promising mRNA delivery systems, their efficacy in hard-to-transfect cells such as primary T lymphocytes is often limited as is their cell and organ tropism. To address these problems, considerable attention has been placed on structural screening of various lipid and cation components of mRNA delivery systems. Here, we disclose a class of charge-altering releasable transporters (CARTs) that differ from previous CARTs based on their beta-amido carbonate backbone (bAC) and side chain spacing. These bAC-CARTs exhibit enhanced mRNA transfection in primary T lymphocytes in vitro and enhanced protein expression in vivo with highly selective spleen tropism, supporting their broader therapeutic use as effective polyanionic delivery systems.

Light-Driven Four-Component Reaction with Boronic Acid Derivatives as Alkylating Agents: An Amine/Imine-Mediated Activation Approach.

Herein, we describe a one-pot aminoalkylation of styrene derivatives with boronic acids (BAs) and boronic acid pinacol esters as radical precursors for the synthesis of complex secondary amines in moderate to high yields through a mild and easily accessible organophotoredox-catalytic four-component reaction. Additionally, we report for the first time in a photoredox process the activation of alkyl boronic acid derivatives by imines, which play a dual role in the reaction as both substrate and Lewis base activator. The protocol applicability was greatly enhanced by its successful adaptation to photoflow reactors.

Circular RNA vaccine induces potent T cell responses.

Circular RNAs (circRNAs) are a class of RNAs commonly found across eukaryotes and viruses, characterized by their resistance to exonuclease-mediated degradation. Their superior stability compared to linear RNAs, combined with previous work showing that engineered circRNAs serve as efficient protein translation templates, make circRNA a promising candidate for RNA medicine. Here, we systematically examine the adjuvant activity, route of administration, and antigen-specific immunity of circRNA vaccination in mice. Potent circRNA adjuvant activity is associated with RNA uptake and activation of myeloid cells in the draining lymph nodes and transient cytokine release. Immunization of mice with engineered circRNA encoding a protein antigen delivered by a charge-altering releasable transporter induced innate activation of dendritic cells, robust antigen-specific CD8 T cell responses in lymph nodes and tissues, and strong antitumor efficacy as a therapeutic cancer vaccine. These results highlight the potential utility of circRNA vaccines for stimulating potent innate and T cell responses in tissues.

Association of polymorphisms rs4680 of the Catechol-O-Methyltransferase gene and rs6265 of the brain derived neurotrophic factor gene with the behavioral inhibition and behavioral activation systems.

Background: The Behavioral Inhibition System (BIS) comprises limbic circuitry implicated in avoidance behaviors. Its increased activation has been identified as a risk factor for anxiety and depressive disorders. In addition, both Catechol-O-Methyltransferase (COMT) and Brain Derived Neurotrophic Factor (BDNF) have been postulated as candidate genes that constitute a vulnerability for the onset of anxiety and depressive disorders. The aim of this study was to evaluate the possible association between the rs4680 polymorphism of the COMT gene and the rs6265 polymorphism of the BDNF gene with the BIS and the Behavioral Activation System (BAS) in a population sample from Colombia. Methods: Genetic information was obtained by extracting DNA from blood samples of 80 participants and using Taqman probes designed for each polymorphism. In addition, participants completed a BIS/BAS scale in order to establish a neuropsychological classification. Results: The frequency of the Met allele of the BDNF gene was greater in the group with BIS sensitivity compared to the group with BAS sensitivity. On the contrary, the frequency of the Met allele of the COMT gen did not show a significant association with the BIS. Conclusions: The rs6265 polymorphism of BDNF gene is associated with the BIS which in turn constitutes a risk factor for anxiety and depression.

Engineering circular RNA for enhanced protein production.

Circular RNAs (circRNAs) are stable and prevalent RNAs in eukaryotic cells that arise from back-splicing. Synthetic circRNAs and some endogenous circRNAs can encode proteins, raising the promise of circRNA as a platform for gene expression. In this study, we developed a systematic approach for rapid assembly and testing of features that affect protein production from synthetic circRNAs. To maximize circRNA translation, we optimized five elements: vector topology, 5' and 3' untranslated regions, internal ribosome entry sites and synthetic aptamers recruiting translation initiation machinery. Together, these design principles improve circRNA protein yields by several hundred-fold, provide increased translation over messenger RNA in vitro, provide more durable translation in vivo and are generalizable across multiple transgenes.

IgG subclasses in New World Monkeys: an issue for debate?

Immunoglobulin G (IgG) is an essential antibody in adaptive immunity; a differential expansion of the gene encoding the Fc region (IGHG) of this antibody has been observed in mammals. Like humans, animal biomedical models, such as mice and macaques, have four functional genes encoding 4 IgG subclasses; however, the data for New World monkeys (NWM) seems contentious. Some publications argue for the existence of a single-copy gene for IgG Fc; however, a recent paper has suggested the presence of IgG subclasses in some NWM species. Here, we evaluated the genetic distances and phylogenetic relationships in NWM to assess the presence of IgG subclasses using the sequences of IGHG genes from 13 NWM species recovered from genomic data and lab PCR and cloning-based procedures available in GenBank. The results show that several sequences do not cluster into the expected taxon, probably due to cross-contamination during laboratory procedures, and consequently, they appear to be wrongly assigned. Additionally, several sequences reported as subclasses were shown to be 100% identical in the CH domains. The data presented here suggests that there is not enough evidence to establish the presence of IgG subclasses in NWM.

Pathological Correlations of Neuropsychiatric Symptoms in Institutionalized People with Dementia.

BACKGROUND: Comprehensive clinicopathological studies of neuropsychiatric symptoms (NPS) in dementia are lacking. OBJECTIVE: To describe the pathological correlations of NPS in a sample of institutionalized people with dementia. METHODS: We studied 59 people who were consecutively admitted to a nursing home and donated their brain. Correlations between pathological variables and NPS upon admission (n = 59) and at one-year follow-up assessment (n = 46) were explored and confirmed using bivariate and multivariate statistical methods. RESULTS: Mean (SD) age at admission was 83.2 (6.4) years and mean (SD) age at demise was 85.4 (6.6); 73% of the subjects were female and 98% presented advanced dementia. The most frequent etiological diagnosis was Alzheimer's disease (AD; 74.6% clinical diagnosis, 67.8% pathological diagnosis). The pathological diagnosis of AD was associated with aggression (ß est 0.31), depression (ß est 0.31), anxiety (ß est 0.38), and irritability (ß est 0.28). Tau stage correlated with aggressive symptoms (ß est 0.32) and anxiety (ßest 0.33). Coexistence of AD and Lewy body pathology was associated with depression (ß est 0.32), while argyrophilic grains were associated with eating symptoms (ß est 0.29). Predictive models were achieved for apathy, including cognitive performance, basal ganglia ischemic lesions, and sex as predictors (R2 0.38) and for sleep disorders, including pathological diagnosis of AD and age at demise (R2 0.18) (all p-values <0.05, unadjusted). CONCLUSION: AD was the main pathological substrate of NPS in our sample of very elderly people with advanced dementia. However, correlations were mild, supporting a model of focal/asymmetric rather than diffuse brain damage, along with relevance of environmental and other personal factors, in the genesis of those symptoms.

Genomic analyses reveal two species of the matamata (Testudines: Chelidae: Chelus spp.) and clarify their phylogeography.

The matamata is one of the most charismatic turtles on earth, widely distributed in northern South America. Debates have occurred over whether or not there should be two subspecies or species recognized due to its geographic variation in morphology. Even though the matamata is universally known, its natural history, conservation status and biogeography are largely unexplored. In this study we examined the phylogeographic differentiation of the matamata based on three mitochondrial DNA fragments (2168 bp of the control region, cytochrome oxidase subunit I, and the cytochrome b gene), one nuclear genomic DNA fragment (1068 bp of the R35 intron) and 1661 Single Nucleotide Polymorphisms (SNPs). Our molecular and morphological analyses revealed the existence of two distinct, genetically deeply divergent evolutionary lineages of matamatas that separated in the late Miocene (approximately 12.7 million years ago), corresponding well to the time when the Orinoco Basin was established. As a result of our analyses, we describe the genetically and morphologically highly distinct matamata from the Orinoco and Río Negro Basins and the Essequibo drainage as a species new to science (Chelus orinocensis sp. nov.). Chelus fimbriata sensu stricto is distributed in the Amazon Basin and the Mahury drainage. Additionally, the analyses revealed that each species displays phylogeographic differentiation. For C. orinocensis, there is moderate mitochondrial differentiation between the Orinoco and the Río Negro. For C. fimbriata, there is more pronounced differentiation matching different river systems. One mitochondrial clade was identified from the Amazon, Ucayali, and Mahury Rivers, and another one from the Madeira and Jaci Paraná Rivers. The C. orinocensis in the Essequibo and Branco Rivers have haplotypes that constitute a third clade clustering with C. fimbriata. Phylogenetic analyses of the R35 intron and SNP data link the matamatas from the Essequibo and Branco with the new species, suggesting past gene flow and old mitochondrial introgression. Chelus orinocensis is collected for the pet trade in Colombia and Venezuela. However, neither the extent of the harvest nor its impact are known. Hence, it is crucial to gather more information and to assess its exploitation throughout its distribution range to obtain a better understanding of its conservation status and to design appropriate conservation and management procedures. RESUMEN: La matamata es una de las tortugas más carismáticas del mundo, ampliamente distribuida en el norte de Sudamérica. Debido a su variación morfológica geográfica, se debate sobre el reconocimiento de dos subespecies o especies. A pesar de que la matamata es universalmente conocida, su historia natural, estado de conservación y biogeografía han sido muy poco estudiados. En este estudio examinamos la diferenciación filogeográfica de las matamatas en base ​​a tres fragmentos de ADN mitocondrial (2168 pb de la región de control, la subunidad I del citocromo oxidasa y el gen del citocromo b), un fragmento de ADN genómico nuclear (1068 pb del intrón R35) y 1661 polimorfismos de nucleótido único (SNPs). Nuestros análisis moleculares y morfológicos revelaron la existencia de dos linajes evolutivos distintos de matamatas, genéticamente divergentes que se separaron en el Mioceno tardio (hace aproximadamente 12.7 millones de años), correspondiendo al tiempo en que se estableció la cuenca del Orinoco. Como resultado de nuestros análisis, describimos las genéticamente y morfológicamente distintas matamatas de las cuencas del Orinoco, Río Negro y Essequibo como una especie nueva para la ciencia (Chelus orinocensis sp. nov.). Chelus fimbriata sensu stricto se distribuye en la cuenca del Amazonas y en el drenaje del Mahury. Adicionalmente, los análisis revelaron que cada especie muestra diferenciación filogeográfica. Para C. orinocensis, hay una moderada diferenciación mitocondrial entre el Orinoco y el Río Negro. Para C. fimbriata, hay una diferenciación más pronunciada, concordando con los diferentes sistemas fluviales. Se identificó un clado de los ríos Amazonas, Ucayali y Mahury y otro de los ríos Madeira y Jaci Paraná. Las C. orinocensis de los ríos Essequibo y Branco tienen haplotipos que constituyen un tercer clado que se agrupa con C. fimbriata. Los análisis filogenéticos del intrón R35 y los datos de SNP asocian las matamatas de Essequibo y Branco con la nueva especie, sugiriendo flujo de genes pasado ​​e introgresión mitocondrial antigua. Chelus orinocensis se colecta para el comercio de mascotas en Colombia y Venezuela. Sin embargo, ni se conoce el alcance de las colectas ni su impacto. Por lo tanto, es crucial recopilar más información y evaluar su explotación en todo su rango de distribución, comprender mejor su estado de conservación y para diseñar acciones apropiadas de conservación y manejo.

Transition-Metal-Free Total Synthesis and Revision of the Absolute Configuration of Pipermethystine.

Starting from 3-hydroxy piperidines, a novel transition-metal-free strategy to 5-hydroxy-5,6-dihydro-2(1H)pyridones is reported. This unprecedented approach, which provides a practical, economical, and ecofriendly alternative to either the classical ring-closing metathesis of N-homoallyl-unsaturated amides or the dehydrogenation of amides, occurs by means of a triple C-H functionalization of three unreactive piperidine sp3 carbons. The completion of the total synthesis revealed that the natural levo-isomer possesses the R absolute configuration, not S.

N6-Methyladenosine Modification Controls Circular RNA Immunity.

Circular RNAs (circRNAs) are prevalent in eukaryotic cells and viral genomes. Mammalian cells possess innate immunity to detect foreign circRNAs, but the molecular basis of self versus foreign identity in circRNA immunity is unknown. Here, we show that N6-methyladenosine (m6A) RNA modification on human circRNAs inhibits innate immunity. Foreign circRNAs are potent adjuvants to induce antigen-specific T cell activation, antibody production, and anti-tumor immunity in vivo, and m6A modification abrogates immune gene activation and adjuvant activity. m6A reader YTHDF2 sequesters m6A-circRNA and is essential for suppression of innate immunity. Unmodified circRNA, but not m6A-modified circRNA, directly activates RNA pattern recognition receptor RIG-I in the presence of lysine-63-linked polyubiquitin chain to cause filamentation of the adaptor protein MAVS and activation of the downstream transcription factor IRF3. CircRNA immunity has considerable parallel to prokaryotic DNA restriction modification system that transforms nucleic acid chemical modification into organismal innate immunity.

Factores de predisposición genéticos y epigenéticos de los trastornos de ansiedad / Genetic and epigenetic predisposing factors of anxiety disorders

Los trastornos de ansiedad constituyen un grupo de alteraciones psicológicas y neurológicas que representan varias formas de miedo y ansiedad anormales o patológicas (Orozco & Baldares, 2012). Aun cuando alrededor del 14% de la población del planeta ha sufrido algún trastorno de ansiedad, las causas que desencadenan el mismo no son del todo claras (Posada, 2013). La aproximación clásica de los estudios para la identificación de los factores de predisposición de estos trastornos neuropsiquiátricos se ha orientado a las teorías de la personalidad como la Teoría de Eysenck (Mitchell & Kumari, 2016) y la Teoría Bio-Psicológica de la personalidad (Knyazev, Pylkova, Slobodskoj-Plusnin, Bocharov, & Ushakov, 2015). Sin embargo, a partir de estos estudios, han surgido nuevas propuestas involucrando los aspectos neuroanatómicos y neurofuncionales. La transmisión eléctrica y química de la información y como esta se asocia a distintas conductas demuestran la relevación de la regulación de la producción y recaptación de neurotransmisores en sistema nervioso central (SNC). Aunque esta regulación se encuentra directamente relacionada con la expresión genética, em tanto se han identificado ciertos genes candidatos que aportan un porcentaje a esta predisposición, estos no son totalmente determinantes. Actualmente, dado a este vacío, se ha comenzado a investigar la influencia de factores epigenéticos que en conjunto con los factores genéticos permitirían ampliar la explicación de los factores de predisposición de ciertos trastornos neuropsiquiátricos que anteriormente eran considerados de etiología ambiental

Anxiety disorders are a group of psychological and neurological disorders that represent various forms of abnormal or pathological fear and anxiety (Orozco & Baldares, 2012). Even though around 14% of the planet's population has suffered from an anxiety disorder, the causes that trigger it are not entirely clear (Posada, 2013). The classical approach of studies for the identification of the predisposing factors of these neuropsychiatric disorders has been oriented to personality theories such as the Eysenck Theory (Mitchell & Kumari, 2016) and the Bio-Psychological Theory of Personality (Knyazev, Pylkova, Slobodskoj-Plusnin, Bocharov, & Ushakov, 2015). However, from these studies, new proposals involving neuroanatomical and neurofunctional aspects have emerged. The electrical and chemical transmission of the information and how it is associated with different behaviors demonstrate the relief of the regulation of the production and reuptake of neurotransmitters in the central nervous system (CNS). This regulation is directly related to genetic expression, however, although certain candidate genes that contribute a percentage to this predisposition have been identified, these are not totally determinant (Montag, Reuter, Newport, Elger & Weber, 2008). Currently, given this gap, we have begun to investigate the influence of epigenetic factors that, together with genetic factors, would allow us to expand the explanation of the predisposing factors of certain neuropsychiatric disorders that were previously considered to be of environmental etiology

Hábitos de higiene bucal y caries dental en escolares de primer año de tres escuelas públicas / Oral hygiene habits and dental caries in first-grade school children of three public schools

Introducción: los factores asociados a la producción de caries en la infancia son dietéticos y ambientales. Los primeros incluyen el alto consumo de dulces y líquidos endulzados, y en los segundos se circunscriben el bajo nivel educativo, la ausencia de hábitos higiénicos y la falta de accesibilidad a los servicios de salud. Objetivo: establecer la relación entre los hábitos de higiene bucal y caries dental en escolares de primer año de primaria de tres escuelas públicas. Metodología: estudio correlacional-analítico, se aplicó una encuesta a 259 niños y a sus padres sobre hábitos de higiene bucal. Se valoró clínicamente la boca y dentadura de los infantes. La prueba de hipótesis fue con coeficiente de correlación de Pearson y análisis de regresión lineal. Resultados: la prevalencia de caries fue del 51%, la presencia de caries clase I fue mayor en escolares de la escuela de nivel socioeconómico bajo (33%). La frecuencia de cepillado dental es de dos veces o menos al día, con omisión del cepillado nocturno. Conclusiones: el consumo de dulces, aunado a la menor frecuencia de cepillado, se asoció a caries, sobre todo en la población de la escuela primaria de nivel socioeconómico bajo.

Introduction: The factors associated with the production of caries in childhood are dietary and environmental. The former include the high consumption of sweets and sweetened liquids and in the latter, the low educational level, the absence of hygienic habits and the lack of accessibility to health services are circumscribed. Objective: To establish the relationship between oral hygiene habits and dental caries in first-grade public elementary school students. Methods: Correlational-analytical study, a survey was applied to 259 children and their parents on oral hygiene habits. The mouth and teeth of the infants were clinically evaluated. The hypothesis test was with a Pearson correlation coefficient and linear regression analysis. Results: The prevalence of caries was 51%, the presence of class I caries was higher in school children of low socioeconomic level (33%). The frequency of tooth brushing is twice or less per day with omission of night brushing. Conclusions: The consumption of sweets combined with a lower frequency of brushing was associated with caries, especially in the population of the primary school of low socioeconomic status.

Undergraduate research experiences: mentoring, awareness, and perceptions-a case study at a Hispanic-serving institution.

BACKGROUND: Undergraduate research experiences (UREs) have been proposed as means to increase the retention and engagement of minority-and more specifically Hispanic-college students in science, technology, engineering, and mathematics (STEM) majors. This study explores the impact of student characteristics such as gender, classification, ethnicity, and first-generation status on UREs of STEM students through four specific constructs that current literature deem particularly important: (1) research experiences, (2) mentoring experiences, (3) awareness of research opportunities and activities, and (4) perceptions on research. These constructs are here forth referred to as Experiences, Mentoring, Awareness, and Perceptions. The study was conducted at a Hispanic-serving institution (HSI) in Texas, United States (U.S.), where the overall increase in enrollment has been driven by growth in Hispanic student numbers, reflecting the demographic shift of the state and the nation. RESULTS: Participants were recruited to be part of a STEM open house. Thirty-five students participated in the Undergraduate Research Experiences: Mentoring, Awareness, and Perceptions Survey (URE MAPS). This exploratory case study sought to look at student characteristics such as gender, classification, ethnicity, and first-generation status as predictors of UREs. Results show that classification and ethnicity student characteristics are statistically significant predictors of UREs. Although gender and first-generation status regression analysis did not show statistically significant results, crosstabulations looking at correlation among variables yield interesting results. Seven percent of the female respondents responded that they "somewhat agree" with the statement that research is a lonely activity in comparison with 23% of males. The majority (60%) of all respondents who "strongly agreed" with the statement that "research is only for future scientists" were Hispanic, indicating a need to clarify such misconceptions to encourage Hispanic student participation. Most self-identified first-generation participants, of whom 80% were female, reported awareness of faculty research activities, again pointing out gender as an important factor among students' relationship with their professors. Although less than 23% of students noted current participation in mentorship, most of those did report positive impact of this relationship on their attitude and perspective toward their major. CONCLUSIONS: Despite the small sample size and inherent bias in the characteristics of the STEM open house participants, regression analysis informed by crosstabs analysis revealed some important findings. The research suggested higher-than-expected awareness of Latinos and first-generation students of institutional research activities; however, this awareness has not translated in engagement in research activities. The data also indicates the critical need for high-impact UREs and mentorship relationships, as well as for efforts to battle student preconceptions of who can benefit from such experiences. Although this case study focused on LatinX students (LatinX is a gender-neutral term for people of Latin American heritage used in the U.S.) in the U.S., retention of historically underrepresented students in STEM disciplines is a concern shared by many countries around the world. The successful recruitment, retention, and eventual success of students in STEM degrees depend greatly on the type of pathways and support that are offered. UREs might be one of those pathways.

The direct and highly diastereoselective synthesis of 3,4-epoxy-2-piperidones. Application to the total synthesis and absolute configurational assignment of 3α,4α-epoxy-5ß-pipermethystine.

The substrate-controlled asymmetric total synthesis and absolute configurational assignment of biologically active 3α,4α-epoxy-5ß-pipermethystine, a minor component in the aerial parts of kava, has been achieved by featuring, as a key step, the environmentally friendly and direct synthesis of 2,3-epoxyamides from allyl amines. By using the chiron approach, first a carbohydrate-derived dehydropiperidine was prepared and subjected to a stereoselective tandem C-H/C[double bond, length as m-dash]C oxidation reaction. In this attempt, the required α,α-trans-epoxy-2-piperidone skeleton of the kava metabolite precursor was not achieved, although the tandem oxidation was highly stereoselective. However, starting from non-carbohydrate 3-hydroxy-4,5-dehydropiperidine, and using the same tandem oxidation, the target intermediate was obtained in high yield and complete unprecedented anti-stereoselectivity. Since the proposed mechanistic course of this tandem oxidation implies the transient formation of an α,ß-unsaturated amide followed by the subsequent epoxidation reaction, this second approach supports the previously established biotransformation proposal of (-)-pipermethystine to (-)-3α,4α-epoxy-5ß-pipermethystine.