Sweet corn is one of the most important vegetables in the United States and Canada. Here, we present a de novo assembly of a sweet corn inbred line Ia453 with the mutated shrunken2-reference allele ...(Ia453-sh2). This mutation accumulates more sugar and is present in most commercial hybrids developed for the processing and fresh markets. The ten pseudochromosomes cover 92% of the total assembly and 99% of the estimated genome size, with a scaffold N50 of 222.2 Mb. This reference genome completely assembles the large structural variation that created the mutant sh2-R allele. Furthermore, comparative genomics analysis with six field corn genomes highlights differences in single-nucleotide polymorphisms, structural variations, and transposon composition. Phylogenetic analysis of 5,381 diverse maize and teosinte accessions reveals genetic relationships between sweet corn and other types of maize. Our results show evidence for a common origin in northern Mexico for modern sweet corn in the U.S. Finally, population genomic analysis identifies regions of the genome under selection and candidate genes associated with sweet corn traits, such as early flowering, endosperm composition, plant and tassel architecture, and kernel row number. Our study provides a high-quality reference-genome sequence to facilitate comparative genomics, functional studies, and genomic-assisted breeding for sweet corn.
Positron emission tomography (PET) has become an essential clinical tool for diagnosing neurodegenerative diseases with abnormal accumulation of proteins like amyloid-β or tau. Despite many attempts, ...it has not been possible to develop an appropriate radioligand for imaging aggregated α-synuclein in the brain for diagnosing, e.g., Parkinson's Disease. Access to a large animal model with α-synuclein pathology would critically enable a more translationally appropriate evaluation of novel radioligands. We here establish a pig model with cerebral injections of α-synuclein preformed fibrils or brain homogenate from postmortem human brain tissue from individuals with Alzheimer's disease (AD) or dementia with Lewy body (DLB) into the pig's brain, using minimally invasive surgery and validated against saline injections. In the absence of a suitable α-synuclein radioligand, we validated the model with the unselective amyloid-β tracer
CPIB, which has a high affinity for β-sheet structures in aggregates. Gadolinium-enhanced MRI confirmed that the blood-brain barrier was intact. A few hours post-injection, pigs were PET scanned with
CPIB. Quantification was done with Logan invasive graphical analysis and simplified reference tissue model 2 using the occipital cortex as a reference region. After the scan, we retrieved the brains to confirm successful injection using autoradiography and immunohistochemistry. We found four times higher
CPIB uptake in AD-homogenate-injected regions and two times higher uptake in regions injected with α-synuclein-preformed-fibrils compared to saline. The
CPIB uptake was the same in non-injected (occipital cortex, cerebellum) and injected (DLB-homogenate, saline) regions. With its large brain and ability to undergo repeated PET scans as well as neurosurgical procedures, the pig provides a robust, cost-effective, and good translational model for assessment of novel radioligands including, but not limited to, proteinopathies.
Maize seeds provide a major component of the calories in the human diet, are critical as a feed source in animal agriculture, and are an important source of biorenewable raw materials. Endosperm ...tissue accounts for approximately 80% of seed weight, and is the site where carbohydrate and protein storage end products are produced in this net anabolic system. Sucrose supplied from photosynthetic tissues of the maternal plant is transported to growing seeds where it is divided between catabolic pathways that generate ATP and anabolic biosynthetic processes that utilize ATP to generate starch and storage proteins. Considering the high degree of ATP requirement, the fact that maize endosperm is an extremely hypoxic environment raises questions about how energy is generated, and the net efficiency of the system for product formation. This project tested the hypothesis that fully oxidative metabolism is not required for normal kernel development, and accordingly that ATP is generated exclusively or substantially through fermentative processes. To do so, RNAi technology was utilized to inactivate the 2‐oxoglutarate dehydrogenase (ODH) step of the citric acid cycle. T‐DNA vectors were constructed that expressed a double stranded RNA structure containing sequences homologous to both of the maize mRNAs encoding the E2 subunit of this enzyme. Highly active, tissue specific promoters were used to restrict the effects of the transgene exclusively to endosperm tissue. Plants were generated containing the anti‐ODH transgene, and subsequent crosses have established segregating populations of sibling kernels that either contain or lack that element. ODH activity and protein abundance in endosperm tissue will be measured to verify that the transgene is effective in inactivating the targeted enzyme activity. Subsequently, segregating kernel populations will be compared regarding growth rate over the course of development, mature kernel weight and composition, and global metabolite profiles. These studies will reveal the extent to which ODH is required for starch and storage protein synthesis to proceed in developing maize endosperm. This will reveal whether normal ATP generation in this tissue requires oxidative processes or, alternatively, whether fermentative processes can be sufficient to provide the energy required for the massive amount of starch and protein synthesis that makes maize such an important agronomic resource. Answering this question will enable future efforts to improve maize yields and grain quality.
Support or Funding Information
This research was supported by NSF award 1517256 to A.M.M. and T.A.H.‐B.
This is from the Experimental Biology 2019 Meeting. There is no full text article associated with this published in The FASEB Journal.
We used 2012-2015 data from the Colorado Pregnancy Risk Assessment Monitoring System to describe changes in self-reported physical activity (PA) before and during pregnancy and used logistic ...regression to examine factors associated with regular PA. The prevalence of regular PA (ie, 30 or more minutes per day on 5 or more days per week) was 19.1% before pregnancy and decreased to 10.2% during pregnancy. At both times, adjusted odds of regular PA were lower among women who were overweight or had obesity before pregnancy than among those with normal weight. Findings suggest that most women with a recent live birth in Colorado, particularly those who are overweight or have obesity, are not obtaining many health benefits of PA either before or during pregnancy.
A positron emission tomography (PET) radiotracer to neuroimage α-synuclein aggregates would be a crucial addition for early diagnosis and treatment development in disorders such as Parkinson's ...disease, where elevated aggregate levels are a histopathological hallmark. The radiotracer (d3)-11CMODAG-001 has recently shown promise for visualization of α-synuclein pre-formed fibrils (α-PFF) in rodents. We here test the radiotracer in a pig model where proteins are intracerebrally injected immediately before scanning. Four pigs were injected in one hemisphere with 150 μg α-PFF, and in the other hemisphere, either 75 μg α-PFF or human brain homogenate from either dementia with Lewy bodies (DLB) or Alzheimer's disease (AD) was injected. All pigs underwent one or two (d3)-11CMODAG-001 PET scans, quantified with the non-invasive Logan graphical analysis using the occipital cortex as a reference region.
The α-PFF and AD homogenate injected brain regions had high uptake of (d3)-11CMODAG-001 compared to the occipital cortex or cerebellum. BPND values in 150 μg α-PFF injected regions was 0.78, and in the AD homogenate injected regions was 0.73. By contrast, the DLB homogenate injected region did not differ in uptake and clearance compared to the reference regions. The time-activity curves and BPND values in the 150 μg and 75 μg injected regions of α-PFFs show a dose-dependent effect, and the PET signal could be blocked by pretreatment with unlabeled MODAG-001.
We find that both α-PFF and AD brain homogenates give rise to increased binding of (d3)-11CMODAG-001 when injected into the pig brain. Despite its limited specificity for cerebral α-synuclein pathology, (d3)-11CMODAG-001 shows promise as a lead tracer for future radiotracer development.
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