Wnt signaling regulates multiple aspects of vertebrate central nervous system (CNS) development, including neurogenesis. However, vertebrate genomes can contain up to 25 Wnt genes, the functions of which are poorly characterized partly due to redundancy in their expression. To identify candidate Wnt genes as candidate mediators of pathway activity in specific brain progenitor zones, we have performed a comprehensive expression analysis at three different stages during zebrafish development. Antisense RNA probes for 21 Wnt genes were generated from existing and newly synthesized cDNA clones and used for in situ hybridization on whole embryos and dissected brains. As in other species, we found that Wnt expression patterns in the embryonic zebrafish CNS are complex and often redundant. We observed that progenitor zones in the telencephalon, dorsal diencephalon, hypothalamus, midbrain, midbrain-hindbrain boundary, cerebellum and retina all express multiple Wnt genes. Our data identify 12 specific ligands that can now be tested using loss-of-function approaches.

While innate behaviors are conserved throughout the animal kingdom, it is unknown whether common signaling pathways regulate the development of neuronal populations mediating these behaviors in diverse organisms. Here, we demonstrate that the Wnt/ß-catenin effector Lef1 is required for the differentiation of anxiolytic hypothalamic neurons in zebrafish and mice, although the identity of Lef1-dependent genes and neurons differ between these 2 species. We further show that zebrafish and Drosophila have common Lef1-dependent gene expression in their respective neuroendocrine organs, consistent with a conserved pathway that has diverged in the mouse. Finally, orthologs of Lef1-dependent genes from both zebrafish and mouse show highly correlated hypothalamic expression in marmosets and humans, suggesting co-regulation of 2 parallel anxiolytic pathways in primates. These findings demonstrate that during evolution, a transcription factor can act through multiple mechanisms to generate a common behavioral output, and that Lef1 regulates circuit development that is fundamentally important for mediating anxiety in a wide variety of animal species.

Gene silencing can occur either through repression of transcription, termed transcriptional gene silencing (TGS), or through translation repression andmRNA degradation, termed posttranscriptional gene silencing (PTGS). PTGS results from sequence-specific mRNA degradation in the cytoplasm without dramatic changes in transcription of corresponding gene in nucleus. Both TGS and PTGS are used to regulate endogenous genes. Interestingly, mechanisms for gene silencing also protect the genome from transposons and viruses. In this paper, we first review RNAi mechanism and then focus on some of its applications in biomedical research such as treatment for HIV, viral hepatitis, cardiovascular and cerebrovascular diseases, metabolic disease, neurodegenerative disorders and cancer.

Since coronavirus disease 2019 (covid-19) has continued to spread globally, many countries have progressed clinical trials and started vaccinations at the end of December 2020. This report aims to analyze the association of COVID-19 vaccine distribution and two macro-socioeconomics measures, including human development index (HDI) and Gross domestic product (GDP), among 25 countries till the first week of February 2021. Our results indicate that a higher GDP per Capita is positively associated with higher COVID-19 vaccine distribution. However, UAE and Israel have more successful vaccine distribution outcomes regardless of their GDP. In addition, the result shows HDI does not have a significant relationship with vaccine distribution. Although these macro-socioeconomic measures may be counted as a vital indicator for vaccine distribution, other factors may play roles in vaccine distribution, including well-developed health infrastructure, a centralized political system, and population size.

Objective: The COVID-19 pandemic could be a significant health issue for the elderly population and those with pre-excising chronic condition. In response to the pandemic health care services have increased the use of telehealth medicine. The propose of this study is to examine factors associated with access to telemedicine before and after COVID-19 based on sociodemographic factors and type of chronic disease. Method: We have used data from the Research and Development Survey (RANDS) at two different time points Data collection for the first wave occurred between June 9, 2020 and July 6, 2020 (n= 6786), second wave was between August 3, 2020 and August 20, 2020 (n=5972). Three questions have been asked from the participant: 1) did the provider offer telemedicine before the pandemic? 2) does the provider offer telemedicine during the pandemic? And 3) have the participants schedule telemedicine appointments? Result: In both waves, 62 % of the participants reported providers did not have telemedicine services prior to the COVID-19 pandemic. However, we found a 22% increase in offering telemedicine in six first month of the COVID-19 pandemic. The finding shows almost no change in providing telemedicine between June and August. The data indicates just a 0.5% and 0.1% increase in accessing telemedicine, and scheduling in August than June, respectively. Patients older than 65 had higher access to telemedicine and had higher scheduling frequencies than other age groups, while they had the lowest access prior to the COVID-19. Blacks had the highest access to telemedicine services than other races (40%). Additionally, females, higher education, and living in metropolitan areas were associated with higher access and scheduling during the pandemic. There was a variation of access and scheduling in different chronic diseases, however, providers offered more remote services for those who diagnosed by diabetes. Conclusion: The aim of telemedicine is to reduce disparities in healthcare access. The findings of this study show telemedicine has reduced racial disparities and provided greater accessibility for older groups. However, spatial and educational disparities are still noticeable. Research is necessary to examine how healthcare must address the socioeconomic heterogeneity in telemedicine by avoiding further disparities. Key terms: COVID-19, Telemedicine, health disparities, chronic condition, access to care