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Ribosome biogenesis is a fundamental and highly orchestrated process that involves hundreds of ribosome biogenesis factors. Despite advances that have been made in yeast, the molecular mechanism of ribosome biogenesis remains largely unknown in plants. We uncovered a WD40 protein, Shrunken and Embryo Defective Kernel 1 (SHREK1), and showed that it plays a crucial role in ribosome biogenesis and kernel development in maize (Zea mays). The shrek1 mutant shows an aborted embryo and underdeveloped endosperm and embryo-lethal in maize. SHREK1 localizes mainly to the nucleolus and accumulates to high levels in the seed. Depleting SHREK1 perturbs pre-rRNA processing and causes imbalanced profiles of mature rRNA and ribosome. The expression pattern of ribosomal-related genes is significantly altered in shrek1. Like its yeast (Saccharomyces cerevisiae) ortholog Periodic tryptophan protein 1 (PWP1), SHREK1 physically interacts with ribosomal protein ZmRPL7a, a transient component of the PWP1-subcomplex involved in pre-rRNA processing in yeast. Additionally, SHREK1 may assist in the A3 cleavage of the pre-rRNA in maize by interacting with the nucleolar protein ZmPOP4, a maize homolog of the yeast RNase mitochondrial RNA-processing complex subunit. Overall, our work demonstrates a vital role of SHREK1 in pre-60S ribosome maturation, and reveals that impaired ribosome function accounts for the embryo lethality in shrek1. [ABSTRACT FROM AUTHOR]

Oral fluid (OF) is a valuable specimen for driving under the influence of drugs (DUID) applications. This study demonstrates the implementation of the first comprehensive OF drug testing program in the United States, including approved roadside screening OF devices for law enforcement and validated liquid chromatography–tandem mass spectrometry (LC–MS-MS) confirmation methods. Three roadside OF screening devices were evaluated: the Dräger DrugTest® 5000, Abbott SoToxa®, and Randox Evidence MultiSTAT™. Two qualitative LC–MS-MS confirmation methods were validated per ASB Standard 036. The first method utilized an automated dispersive pipette extraction extraction using Integra and Hamilton STARlet platforms for drugs of abuse. The second method used a liquid–liquid extraction to detect cannabinoids. The prevalence of drugs in blood and OF was monitored over 5 years of casework. Calibration curves were analyzed with each batch to monitor OF concentrations for research purposes. Three roadside OF screening devices were deemed fit for purpose. Devices demonstrated appropriate sensitivity, specificity, positive and negative predictive values, and accuracy above 80% for targeted drugs except for benzodiazepines (DrugTest® 5000) and amphetamine (SoToxa®). The validated LC–MS-MS OF confirmation methods met the National Safety Council-recommended cutoffs for 18/21 (86%) of the targets. Over 5 years of casework, THC and cocaine were detected at a positivity rate of 90% and 97% in OF versus 75% and 44% in blood, respectively. OF:blood ratios exceeded unity for parent drugs. Median concentrations of THC in OF and blood were 31 and 3.5 ng/mL, respectively. OF is a viable alternative or supplemental specimen for DUID investigations. Collecting OF close to the driving event increases the opportunity to identify pharmacologically active substances, and when combined with blood analysis results, an elevated OF:blood ratio provides valuable information for DUID investigation purposes. [ABSTRACT FROM AUTHOR]

Movement proteins (MPs) encoded by plant viruses deliver viral genomes to plasmodesmata (PD) to ensure intracellular and intercellular transport. However, how the MPs encoded by monopartite geminiviruses are targeted to PD is obscure. Here, we demonstrate that the C5 protein of tomato yellow leaf curl virus (TYLCV) anchors to PD during the viral infection following trafficking from the nucleus along microfilaments in Nicotiana benthamiana. C5 could move between cells and partially complement the traffic of a movement-deficient turnip mosaic virus (TuMV) mutant (TuMV-GFP-P3N-PIPO-m1) into adjacent cells. The TYLCV-C5 null mutant (TYLCV-mC5) attenuates viral pathogenicity and decreases viral DNA and protein accumulation, and ectopic overexpression of C5 enhances viral DNA accumulation. Interaction assays between TYLCV-C5 and the other eight viral proteins described in TYLCV reveal that C5 associates with C2 in the nucleus and with V2 in the cytoplasm and at PD. The V2 protein is mainly localized in the nucleus and cytoplasmic granules when expressed alone; in contrast, V2 forms small punctate granules at PD when co-expressed with C5 or in TYLCV-infected cells. The interaction of V2 and C5 also facilitates their nuclear export. Furthermore, C5-mediated PD localization of V2 is conserved in two other geminiviruses. Therefore, this study solves a long-sought-after functional connection between PD and the geminivirus movement and improves our understanding of geminivirus-encoded MPs and their potential cellular and molecular mechanisms. [ABSTRACT FROM AUTHOR]