NORTH AMERICAN CONTINENT - A NEW SOURCE OF WILD LACTUCA SPP. GERMPLASM VARIABILITY FOR FUTURE LETTUCE BREEDING

In the years 2002-2008, missions were undertaken in the USA and Canada to search for wild and weedy Lactuca species. Altogether, 16 states in the USA (Arizona, California, Colorado, Idaho, Iowa, Minnesota, Montana, Nevada, New York, North Carolina, Oregon, South Dakota, Utah, Washington, Wisconsin and Wyoming) and two provinces in Canada (Ontario and Quebec) were visited. In total, seven wild and weedy Lactuca spp. (L. serriola, L. saligna, L. virosa, L. canadensis, L. biennis, L. floridana, and L. ludoviciana), an interspecific hybrid (L. canadensis × L. ludoviciana), and an undetermined Lactuca species were observed and collected in 200 locations. In this paper, we present new data on the distribution and ecobiology of Lactuca naturally occurring in North America. Morphological assessment of L. serriola samples acquired from North America revealed considerable intraspecific phenotypic variation. Although L. serriola samples originating from various eco-geographical regions differed significantly in their genetic polymorphisms (based on AFLP markers), little variation was observed in their absolute DNA content.This is a proceeding from Acta Horticulturae 918 (2011): 475, doi: 10.17660/ActaHortic.2011.918.59.</p

Less Adaptive or More Maladaptive? A Meta-analytic Investigation of Procrastination and Coping

Despite the theoretical and empirical accounts of trait procrastination as reflecting avoidance of aversive tasks as a means of mood repair, research documenting its links to coping is scarce and inconsistent. There is also little if any research to date examining whether coping strategies might explain the procrastination-stress relationship. The current research aimed to address these issues by integrating current research on procrastination and coping with our own data into a first meta-analysis of the associations of procrastination with adaptive and maladaptive coping and then testing the potential role of coping for understanding the procrastination-stress relationship. In Study 1, a literature search yielded five published papers and three theses, which were supplemented by seven unpublished data sets comprising 15 samples (N=4357). Meta-analyses revealed that procrastination was positively associated with maladaptive coping (average r=.31) and negatively associated with adaptive coping (average r=-.24). In Study 2, a meta-analysis of the indirect effects through coping across four samples revealed that the average indirect effects for maladaptive but not adaptive coping explained the link between procrastination and stress. These findings expand the nomological network of procrastination and highlight the role of maladaptive coping for understanding procrastinators' stress

Alzheimer’s disease genetic risk and cognitive reserve in relationship to long-term cognitive trajectories among cognitively normal individuals

Background: Both Alzheimer’s disease (AD) genetic risk factors and indices of cognitive reserve (CR) influence risk of cognitive decline, but it remains unclear whether they interact. This study examined whether a CR index score modifies the relationship between AD genetic risk factors and long-term cognitive trajectories in a large sample of individuals with normal cognition. Methods: Analyses used data from the Preclinical AD Consortium, including harmonized data from 5 longitudinal cohort studies. Participants were cognitively normal at baseline (M baseline age = 64 years, 59% female) and underwent 10 years of follow-up, on average. AD genetic risk was measured by (i) apolipoprotein-E (APOE) genetic status (APOE-ε2 and APOE-ε4 vs. APOE-ε3; N = 1819) and (ii) AD polygenic risk scores (AD-PRS; N = 1175). A CR index was calculated by combining years of education and literacy scores. Longitudinal cognitive performance was measured by harmonized factor scores for global cognition, episodic memory, and executive function. Results: In mixed-effects models, higher CR index scores were associated with better baseline cognitive performance for all cognitive outcomes. APOE-ε4 genotype and AD-PRS that included the APOE region (AD-PRSAPOE) were associated with declines in all cognitive domains, whereas AD-PRS that excluded the APOE region (AD-PRSw/oAPOE) was associated with declines in executive function and global cognition, but not memory. There were significant 3-way CR index score × APOE-ε4 × time interactions for the global (p = 0.04, effect size = 0.16) and memory scores (p = 0.01, effect size = 0.22), indicating the negative effect of APOE-ε4 genotype on global and episodic memory score change was attenuated among individuals with higher CR index scores. In contrast, levels of CR did not attenuate APOE-ε4-related declines in executive function or declines associated with higher AD-PRS. APOE-ε2 genotype was unrelated to cognition. Conclusions: These results suggest that APOE-ε4 and non-APOE-ε4 AD polygenic risk are independently associated with global cognitive and executive function declines among individuals with normal cognition at baseline, but only APOE-ε4 is associated with declines in episodic memory. Importantly, higher levels of CR may mitigate APOE-ε4-related declines in some cognitive domains. Future research is needed to address study limitations, including generalizability due to cohort demographic characteristics

Visualizing the Needle in the Haystack: In Situ Hybridization With Fluorescent Dendrimers

In situ hybridization with 3DNA™ dendrimers is a novel tool for detecting low levels of mRNA in tissue sections and whole embryos. Fluorescently labeled dendrimers were used to identify cells that express mRNA for the skeletal muscle transcription factor MyoD in the early chick embryo. A small population of MyoD mRNA positive cells was found in the epiblast prior to the initiation of gastrulation, two days earlier than previously detected using enzymatic or radiolabeled probes for mRNA. When isolated from the epiblast and placed in culture, the MyoD mRNA positive cells were able to differentiate into skeletal muscle cells. These results demonstrate that DNA dendrimers are sensitive and precise tools for identifying low levels of mRNA in single cells and tissues

Egg-laying and locomotory screens with C. elegans yield a nematode-selective small molecule stimulator of neurotransmitter release

Nematode parasites of humans, livestock and crops dramatically impact human health and welfare. Alarmingly, parasitic nematodes of animals have rapidly evolved resistance to anthelmintic drugs, and traditional nematicides that protect crops are facing increasing restrictions because of poor phylogenetic selectivity. Here, we exploit multiple motor outputs of the model nematode C. elegans towards nematicide discovery. This work yielded multiple compounds that selectively kill and/or immobilize diverse nematode parasites. We focus on one compound that induces violent convulsions and paralysis that we call nementin. We find that nementin stimulates neuronal dense core vesicle release, which in turn enhances cholinergic signaling. Consequently, nementin synergistically enhances the potency of widely-used non-selective acetylcholinesterase (AChE) inhibitors, but in a nematode-selective manner. Nementin therefore has the potential to reduce the environmental impact of toxic AChE inhibitors that are used to control nematode infections and infestations

Molecular biogeography of planktonic and benthic diatoms in the Yangtze River

Background: Diatoms are of great significance to primary productivity in oceans, yet little is known about their biogeographic distribution in oligotrophic rivers. Results: With the help of metabarcoding analysis of 279 samples from the Yangtze River, we provided the first integral biogeographic pattern of planktonic and benthic diatoms over a 6030 km continuum along the world's third largest river. Our study revealed spatial dissimilarity of diatoms under varying landforms, including plateau, mountain, foothill, basin, foothill-mountain, and plain regions, from the river source to the estuary. Environmental drivers of diatom communities were interpreted in terms of photosynthetically active radiation, temperature, channel slope and nutrients, and human interference. Typical benthic diatoms, such as Pinnularia, Paralia, and Aulacoseira, experienced considerable reduction in relative abundance downstream of the Three Gorges Dam and the Xiluodu Dam, two of the world's largest dams. Conclusions: Our study revealed that benthic diatoms are of particular significance in characterizing motile guild in riverine environments, which provides insights into diatom biogeography and biogeochemical cycles in large river ecosystems