Gastrulation of the mouse embryo entails progressive restriction of lineage potency and the organization of the lineage progenitors into a body plan. Here we performed a high-resolution RNA sequencing analysis on single mid-gastrulation mouse embryos to collate a spatial transcriptome that correlated with the regionalization of cell fates in the embryo. 3D rendition of the quantitative data enabled the visualization of the spatial pattern of all expressing genes in the epiblast in a digital whole-mount in situ format. The dataset also identified genes that (1) are co-expressed in a specific cell population, (2) display similar global pattern of expression, (3) have lineage markers, (4) mark domains of transcriptional and signaling activity associated with cell fates, and (5) can be used as zip codes for mapping the position of single cells isolated from the mid-gastrula stage embryo and the embryo-derived stem cells to the equivalent epiblast cells for delineating their prospective cell fates.

Highlights d Human germline cell specification begins from a transitional pluripotent state d Human primordial germ cells are specified from lineageprimed progenitors d Lineage-primed TFAP2A progenitors have gastrulating and amnion cell identity d TFAP2C regulates SOX17 at the point of human primordial germ cell specification

Despite the importance of the blood-brain barrier in maintaining normal brain physiology and in understanding neurodegeneration and CNS drug delivery, human cerebrovascular cells remain poorly characterized due to their sparsity and dispersion. Here, we perform the first single-cell characterization of the human cerebrovasculature using both ex vivo fresh-tissue experimental enrichment and post mortem in silico sorting of human cortical tissue samples. We capture 31,812 cerebrovascular cells across 17 subtypes, including three distinct subtypes of perivascular fibroblasts as well as vasculature-coupled neurons and glia. We uncover human-specific expression patterns along the arteriovenous axis and determine previously uncharacterized cell type-specific markers. We use our newly discovered human-specific signatures to study changes in 3,945 cerebrovascular cells of Huntington's disease patients, which reveal an activation of innate immune signaling in vascular and vasculature-coupled cell types and the concomitant reduction to proteins critical for maintenance of BBB integrity. Finally, our study provides a comprehensive resource molecular atlas of the human cerebrovasculature to guide future biological and therapeutic studies.

Heat shock transcription factorA2 (HsfA2) is a key regulator in response to heat stress in Arabidopsis (Arabidopsis thaliana), and its heat shock (HS)-induced transcription regulation has been extensively studied. Recently, alternative splicing, a critical posttranscriptional event, has been shown to regulate HS-inducible expression of HsfA2; however, the molecular mechanism remains largely unknown. Here, we demonstrate a new heat stress-induced splice variant, HsfA2-III, is involved in the self-regulation of HsfA2 transcription in Arabidopsis. HsfA2-III is generated through a cryptic 59 splice site in the intron, which is activated by severe heat (42°C-45°C). We confirmed that HsfA2-III encodes a small truncated HsfA2 isoform (S-HsfA2) by an immunoblot assay with anti-S-HsfA2 antiserum. S-HsfA2 has an extra leucine-rich motif next to its carboxyl-terminal truncated DNA-binding domain. The biological significance of S-HsfA2 was further demonstrated by its nuclear localization and heat shock element (HSE)-binding ability. In yeast (Saccharomyces cerevisiae), the leucine-rich motif can inhibit the transcriptional activation activity of S-HsfA2, while it appears not to be required for the truncated DNA-binding domain-mediated binding ability of S-HsfA2-HSE. Further results reveal that S-HsfA2 could bind to the TATA box-proximal clusters of HSE in the HsfA2 promoter to activate its own transcription. This S-HsfA2-modulated HsfA2 transcription is not mediated through homodimer or heterodimer formation with HsfA1d or HsfA1e, which are known transcriptional activators of HsfA2. Altogether, our findings provide new insights into how HS posttranscriptionally regulates HsfA2 expression. Severe HS-induced alternative splicing also occurs in four other HS-inducible Arabidopsis Hsf genes, suggesting that it is a common feature among Arabidopsis Hsfs.

SummaryCaenorhabditis elegans is a leading model organism for studying the basic mechanisms of aging. Progress has been limited, however, by the lack of an automated system for quantitative analysis of longevity and mean lifespan. To address this barrier, we developed 'WormFarm', an integrated microfluidic device for culturing nematodes. Cohorts of 30-50 animals are maintained throughout their lifespan in each of eight separate chambers on a single WormFarm polydimethylsiloxane chip. Design features allow for automated removal of progeny and efficient control of environmental conditions. In addition, we have developed computational algorithms for automated analysis of video footage to quantitate survival and other phenotypes, such as body size and motility. As proof-of-principle, we show here that WormFarm successfully recapitulates survival data obtained from a standard plate-based assay for both RNAi-mediated and dietary-induced changes in lifespan. Further, using a fluorescent reporter in conjunction with WormFarm, we report an age-associated decrease in fluorescent intensity of GFP in transgenic worms expressing GFP tagged with a mitochondrial import signal under the control of the myo-3 promoter. This marker may therefore serve as a useful biomarker of biological age and aging rate.