The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

A robust method of nuclei isolation for single-cell RNA sequencing of solid tissues from the plant genus Populus

: Single-cell transcriptome analysis has been extensively applied in humans and animal models to uncover gene expression heterogeneity between the different cell types of a tissue or an organ. It demonstrated its capability to discover key regulatory elements that determine cell fate during developmental programs. Single-cell analysis requires the isolation and labeling of the messenger RNA (mRNA) derived from each cell. These challenges were primarily addressed in mammals by developing microfluidic-based approaches. For plant species whose cells contain cell walls, these approaches have generally required the generation of isolated protoplasts. Many plant tissues' secondary cell wall hinders enzymatic digestion required for individual protoplast isolation, resulting in an unequal representation of cell types in a protoplast population. This limitation is especially critical for cell types located in the inner layers of a tissue or the inner tissues of an organ. Consequently, single-cell RNA sequencing (scRNA-seq) studies using microfluidic approaches in plants have mainly been restricted to Arabidopsis roots, for which well-established procedures of protoplast isolation are available. Here we present a simple alternative approach to generating high-quality protoplasts from plant tissue by characterizing the mRNA extracted from individual nuclei instead of whole cells. We developed the protocol using two different plant materials with varying cellular complexity levels and cell wall structure, Populus shoot apices, and more lignified stems. Using the 10× Genomics Chromium technology, we show that this procedure results in intact mRNA isolation and limited leakage, with a broad representation of individual cell transcriptomes

Quantitative assessment of intestinal stiffness and associations with fibrosis in human inflammatory bowel disease.

Inflammatory bowel disease (IBD) continues to increase in prevalence in industrialized countries. Major complications of IBD include formation of fibrotic strictures, fistulas, reduced absorptive function, cancer risk, and the need for surgery. In other chronic gastrointestinal disease models, stiffness has been shown to precede fibrosis; therefore, stiffness may be a reasonable indicator of progression toward stricture formation in IBD patients. Herein, we seek to quantify tissue stiffness and characterize fibrosis in patients with IBD and to compare mechanical properties of unaffected human tissue to common animal species used for IBD studies. Inflamed and unaffected tissue from IBD patients and unaffected tissue from mice, pigs, and cows were indented using a custom device to determine the effective stiffness. Histology was performed on matched tissues, and total RNA was isolated from IBD tissue samples and used for gene expression analysis of pro-fibrotic genes. We observed an increase in the effective stiffness (steady-state modulus, SSM) (p < 0.0001) and increased expression of the collagen type I gene (COL1A1, p = 0.01) in inflamed tissue compared to unaffected areas in our IBD patient cohort. We also found that increased staining of collagen fibers in submucosa positively correlated with SSM (p = 0.093). We determined that unaffected animal bowel stiffness is significantly greater than similar human tissues, suggesting additional limitations on animal models for translational investigations regarding stiffness-related hypotheses. Taken together, our data support development of tools for evaluation of bowel stiffness in IBD patients for prognostic applications that may enable more accurate prediction of those who will develop fibrosis and more precise prescription of aggressive therapies

Multi-scale indentation system characterizes mechanical properties of soft tissues.

<p>(A) Custom indentation device with sensor positioned with the cantilever in position to test inflamed ileum. (B) Bovine small bowel positioned under the sensor probe with the mucosa exposed. Hydration was maintained by pooling small volumes of saline solution on and around samples (not seen here to improve visualization of tissue).</p

Tissues with time-dependent mechanical properties reach a quasi-steady-state after stress relaxation during indentation.

<p>Normal force (top, green line) as a function of relaxation time is used in computing the transient modulus (bottom, blue line) based on a modified Hertz contact model (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0200377#pone.0200377.e001" target="_blank">Equation 1</a>). The Steady-State Modulus (SSM) seen at the end of relaxation is reported throughout this work since SSM reduces strain-rate dependencies in determining the properties of a viscoelastic material.</p

Quantitative assessment of intestinal stiffness and associations with fibrosis in human inflammatory bowel disease - Fig 8

<p><b>Representative H&E and Masson’s Trichrome of the cow small bowel (A,B), pig small bowel (C,D), pig colon (E,F), and mouse colon (G,H).</b> The mouse colon has a very distinct muscle layer highlighted by the black arrow (G), while the cow small bowel has a very large area of collagen deposition (B, black star) that is absent in the pig small bowel and colon (black stars, D and F). Scale bar is 100 μm.</p

Fibrotic markers are less prevalent in representative staining of the unaffected regions of bowel than inflamed regions.

<p>Adjacent regions of Ileum (A-D) and colon (E-H) have been labeled with H&E (A,C,E,G) and Trichrome (B,D,F,H) as indicated. Black arrows highlight collagen clustering while black stars illustrate disrupted mucosal layer in inflamed tissue compared to unaffected tissue segments. Scale bar is 100 μm.</p