The Pleiades Promoter Project integrates genomewide bioinformatics with large-scale knockin mouse production and histological examination of expression patterns to develop MiniPromoters and related tools designed to study and treat the brain by directed gene expression. Genes with brain expression patterns of interest are subjected to bioinformatic analysis to delineate candidate regulatory regions, which are then incorporated into a panel of compact human MiniPromoters to drive expression to brain regions and cell types of interest. Using single-copy, homologous-recombination “knockins” in embryonic stem cells, each MiniPromoter reporter is integrated immediately 5′ of the Hprt locus in the mouse genome. MiniPromoter expression profiles are characterized in differentiation assays of the transgenic cells or in mouse brains following transgenic mouse production. Histological examination of adult brains, eyes, and spinal cords for reporter gene activity is coupled to costaining with cell-type–specific markers to define expression. The publicly available Pleiades MiniPromoter Project is a key resource to facilitate research on brain development and therapies.

Macadamia (Macadamia integrifolia, M. tetraphylla and hybrids) is an Australian native nut crop and has a significant economic value in the food industries worldwide. Long juvenility along with traditional breeding strategies impede quick genetic improvement of this crop. The existing cultivars constitute only second to fourth generation of the wild germplasm in the rainforest. The utilisation of molecular markers for genomic selection and genome-wide association studies may accelerate genetic gains. Identification of a robust, reproducible, and cost-effective marker system is instrumental in increasing the efficiency of genomic studies. This study is the first to report the potential of two ultra-high-throughput diversity array technology (DArT) markers (silicoDArT and SNP) in macadamia. Both markers were used to identify the genetic diversity and population structure in 80 macadamia cultivars. Parentage analysis of 25 scions in a rootstock trial was conducted to confirm plant identity where recorded identities did not corroborate with phenotypic field observations. A total of 22,280 silicoDArT and 7,332 SNP markers were reported, of which 11,526 silicoDArT and 3,956 SNP markers were used for analyses after screening with quality control parameters including >95% call rate, >95% reproducibility, and >0.05 one ratio. The average polymorphic information content (PIC) values of silicoDArT and SNP markers were 0.29 and 0.21, respectively. Genetic variance among the cultivars ranged from 0.003 to 0.738 in silicoDArT and 0.004 to 0.412 in SNP markers. Four distinct population groups were identified from SNP data analysis. Most of the accessions used in this study were descended from two or more populations. Cluster analysis clearly separated genotypes of distinct origins, such as the Hawaii Agricultural Experiment Station and Hidden Valley Plantation accessions. Two wild accessions of Macadamia jansenii and M. ternifolia were found to be distantly related to the cultivars. Wild germplasm individuals and their hybrids with cv. ‘660’ formed separate clusters, suggesting that crossing between wild and cultivated genepools can extend genetic diversity. DArTseq-based SNP markers were successfully utilized to confirm the genetic identity of 25 scions in a rootstock trial. Our study suggests that DArT platforms are a robust system for the facilitation of genomic studies with regard to macadamia.

As part of a larger project to sequence the Populus genome and generate genomic resources for this emerging model tree, we constructed a physical map of the Populus genome, representing one of the few such maps of an undomesticated, highly heterozygous plant species. The physical map, consisting of 2802 contigs, was constructed from fingerprinted bacterial artificial chromosome (BAC) clones. The map represents approximately 9.4-fold coverage of the Populus genome, which has been estimated from the genome sequence assembly to be 485 +/- 10 Mb in size. BAC ends were sequenced to assist long-range assembly of whole-genome shotgun sequence scaffolds and to anchor the physical map to the genome sequence. Simple sequence repeat-based markers were derived from the end sequences and used to initiate integration of the BAC and genetic maps. A total of 2411 physical map contigs, representing 97% of all clones assigned to contigs, were aligned to the sequence assembly (JGI Populus trichocarpa, version 1.0). These alignments represent a total coverage of 384 Mb (79%) of the entire poplar sequence assembly and 295 Mb (96%) of linkage group sequence assemblies. A striking result of the physical map contig alignments to the sequence assembly was the co-localization of multiple contigs across numerous regions of the 19 linkage groups. Targeted sequencing of BAC clones and genetic analysis in a small number of representative regions showed that these co-aligning contigs represent distinct haplotypes in the heterozygous individual sequenced, and revealed the nature of these haplotype sequence differences.

Objectives. To determine whether the COVID-19 pandemic affected e-cigarette use among young people in the United States. Methods. Data came from a weekly cross-sectional online survey of youths and young adults (aged 15–24 years). Logistic regression analyses measured odds of past-30-day e-cigarette use (n = 5752) following widespread stay-at-home directives (March 14–June 29, 2020), compared with the pre‒COVID-19 period (January 1–March 13, 2020). Logistic regression among a subsample of current e-cigarette users (n = 779) examined factors associated with reduced use following stay-at-home orders. Results. Odds of current e-cigarette use were significantly lower during the COVID-19 pandemic compared with the pre‒COVID-19 period among youths aged 15 to 17 years (odds ratio [OR] = 0.72; 95% confidence interval [CI] = 0.54, 0.96) and young adults aged 18 to 20 years (OR = 0.65; 95% CI = 0.52, 0.81). E-cigarette users with reduced access to retail environments had higher odds of reporting reduced e-cigarette use (OR = 1.51; 95% CI = 1.07, 2.14). Conclusions. COVID-19 stay-at-home directives present barriers to e-cigarette access and are associated with a decline in e-cigarette use among young people. Public Health Implications. Findings support the urgent implementation of interventions that reduce underage access to e-cigarettes to accelerate a downward trajectory of youth and young adult e-cigarette use. (Am J Public Health. Published online ahead of print April 15, 2021: e1–e9. https://doi.org/10.2105/AJPH.2021.306210 )

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Additional index words. GWAS, nut weight, kernel weight, kernel recovery, SNP markers, breeding Abstract. Current macadamia breeding programs involve a lengthy and laborious twostage selection process: evaluation of a large number of unreplicated seedling progeny, followed by replicated trials of clonally propagated elite seedlings. Yield component traits, such as nut-in-shell weight (NW), kernel weight (KW), and kernel recovery (KR) are commercially important, are more easily measured than yield, and have a higher heritability. A genome-wide association study (GWAS) combined with marker-assisted selection offers an opportunity to reduce the time of candidate evaluation. In this study, a total of 281 progeny from 32 families, and 18 of their 29 parents have been genotyped for 7126 single nucleotide polymorphism (SNP) markers. A GWAS was performed using ASReml with 4352 SNPs. We found five SNPs significantly associated with NW, nine with KW, and one with KR. Further, three of the top 10 markers for NW and KW were shared between the two traits. Future macadamia breeding could involve prescreening of individuals for desired traits using these significantly associated markers, with only predicted elite individuals continuing to the second stage of selection, thus potentially reducing the selection process by 7 years.

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