Using Fluorescence in situ hybridization to study maize lines genetically predicted to have chromosomal abnormalities [abstract]

Abstract only availableSince the 1960s, genetic evidence has indicated chromosome damage and nondisjunction in lines of maize containing knob heterochromatin-bearing chromosomes and at least two B chromosomes. However, at that time researchers lacked the technology to visualize these occurrences. Now, using Fluorescence in situ Hybridization to "paint" and photograph the chromosomes, it is possible to accurately karyotype and identify broken, missing, or extra chromosomes. A line with a very large number of heterochromatic knobs had been crossed with another line containing supernumerary B chromosomes. This F1 hybrid that had been self pollinated (B73+B/K10) was chosen for study by the FISH method because it contains both knobs and B chromosomes, as well as exhibiting abnormalities such as irregular rows, ovule abortion, and defective kernels. This material combined a high knob number with B chromosomes and exhibited properties suggestive of chromosome breakage or nondisjunction. Metaphase spreads from the root tips were prepared and hybridized to fluorescent probes. Spreads were observed using fluorescence microscopy. The majority of the plants studied possessed the normal content of 20 A chromosomes plus varying numbers of B chromosomes. One individual was found with 21 chromosomes that might have resulted from nondisjunction. No chromosomal breakage was evident in this background. FISH proved to be a powerful cytogenetic tool in observing these plants; however, further research on this topic is needed to provide insight into the cause of the genetic abnormalities

Identification of chloroplast DNA insertions in nuclear chromosomes of maize B73 line using the FISH procedure

Abstract only availableIt is known that chloroplast DNA can incorporate itself into the nuclear genome of plants. However, the sites of chloroplast (ct) DNA integration into chromosomes of maize have not yet been analyzed. This project is the first attempt to find the location of the ctDNA on the maize chromosomes. Fluorescent in situ hybridization is a technique that has proved useful in karyotyping and chromosomal mapping in maize. The FISH procedure is being used in this study to discover the location of the ctDNA in the nuclear genome of the inbred line B37. In order to develop ctDNA “probes” for FISH analysis, we have used the polymerase chain reaction (PCR) to produce fragments of ctDNA. Primers were chosen to amplify fragments of 10 kb or larger. The amplified DNAs were purified and labeled with fluorescent dyes and these probes were subsequently hybridized to chromosomes. The probes recognize and bind to the corresponding DNA sequences within the chromosomes. Root tip cells were used to prepare the slides for hybridization. Because the cells are collected during the metaphase stage of division, the chromosomes are compact and more easily visible. Chromosomes that contain ctDNA can be detected using a compound microscope with fluorescent attachments. The location of the ctDNA on the chromosomes is made visible by the fluorescent labeling of the probe. Eight of eleven regions of the chloroplast genome of the B73 line have been specifically amplified and have been observed under the microscope for FISH analysis. This information will contribute to an understanding of the extent and mechanism of transfer of organellar genomes to the nucleus.MU Monsanto Undergraduate Research Fellowshi

The Mid-infrared Instrument for JWST and Its In-flight Performance

The Mid-Infrared Instrument (MIRI) extends the reach of the James Webb Space Telescope (JWST) to 28.5 μm. It provides subarcsecond-resolution imaging, high sensitivity coronagraphy, and spectroscopy at resolutions of λ/Δλ ∼ 100-3500, with the high-resolution mode employing an integral field unit to provide spatial data cubes. The resulting broad suite of capabilities will enable huge advances in studies over this wavelength range. This overview describes the history of acquiring this capability for JWST. It discusses the basic attributes of the instrument optics, the detector arrays, and the cryocooler that keeps everything at approximately 7 K. It gives a short description of the data pipeline and of the instrument performance demonstrated during JWST commissioning. The bottom line is that the telescope and MIRI are both operating to the standards set by pre-launch predictions, and all of the MIRI capabilities are operating at, or even a bit better than, the level that had been expected. The paper is also designed to act as a roadmap to more detailed papers on different aspects of MIRI

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

The Essen stroke risk score predicts recurrent cardiovascular events: a validation within the REduction of Atherothrombosis for Continued Health (REACH) registry.

In outpatients with previous stroke or transient ischemic attack, the ESRS accurately stratifies the risk of recurrent stroke or major vascular events. Patients with a high ESRS should be candidates for intensified secondary prevention strategies

Prevalence, clinical profile, and cardiovascular outcomes of atrial fibrillation patients with atherothrombosis.

Atrial fibrillation is common in patients with atherothrombosis, associated with more frequent fatal and nonfatal CV outcomes, and underuse of oral anticoagulants

The Mid-infrared Instrument for JWST and Its In-flight Performance

The Mid-Infrared Instrument (MIRI) extends the reach of the James Webb Space Telescope (JWST) to 28.5 μm. It provides subarcsecond-resolution imaging, high sensitivity coronagraphy, and spectroscopy at resolutions of λ/Δλ ∼ 100-3500, with the high-resolution mode employing an integral field unit to provide spatial data cubes. The resulting broad suite of capabilities will enable huge advances in studies over this wavelength range. This overview describes the history of acquiring this capability for JWST. It discusses the basic attributes of the instrument optics, the detector arrays, and the cryocooler that keeps everything at approximately 7 K. It gives a short description of the data pipeline and of the instrument performance demonstrated during JWST commissioning. The bottom line is that the telescope and MIRI are both operating to the standards set by pre-launch predictions, and all of the MIRI capabilities are operating at, or even a bit better than, the level that had been expected. The paper is also designed to act as a roadmap to more detailed papers on different aspects of MIRI.ISSN:0004-6280ISSN:1538-3873ISSN:0004-627