Population structure and genetic diversity of Bromus tectorum within the small grain production region of the Pacific Northwest

Bromus tectorum L. is an invasive winter annual grass naturalized across the United States. Numerous studies have investigated B. tectorum population structure and genetics in the context of B. tectorum as an ecological invader of natural areas and rangeland. Despite the wealth of information regarding B. tectorum, previous studies have not focused on, or made comparisons to, B. tectorum as it persists in individual agroecosystems. The objectives of this study were to assess the genetic diversity and structure, the occurrence of generalist and specialist genotypes, and the influence of climate on distribution of B. tectorum sourced exclusively from within small grain production regions of the Pacific Northwest. Genetic diversity of B. tectorum sourced from agronomic fields was found to be similar to what has been observed from other land use histories. Six distinct genetic clusters of B. tectorum were identified, with no evidence to indicate that any of the genetic clusters were better adapted to a particular geographical area or climate within the region. Given the apparent random spatial distribution of B. tectorum genetic clusters at the spatial scale of this analysis, unique genotypes may be well mixed within region, similar to what was reported for other inbreeding weedy grass species.     

Chemical–Genetic Profiling of Imidazo[1,2-a]pyridines and -Pyrimidines Reveals Target Pathways Conserved between Yeast and Human Cells

Small molecules have been shown to be potent and selective probes to understand cell physiology. Here, we show that imidazo[1,2-a]pyridines and imidazo[1,2-a]pyrimidines compose a class of compounds that target essential, conserved cellular processes. Using validated chemogenomic assays in Saccharomyces cerevisiae, we discovered that two closely related compounds, an imidazo[1,2-a]pyridine and -pyrimidine that differ by a single atom, have distinctly different mechanisms of action in vivo. 2-phenyl-3-nitroso-imidazo[1,2-a]pyridine was toxic to yeast strains with defects in electron transport and mitochondrial functions and caused mitochondrial fragmentation, suggesting that compound 13 acts by disrupting mitochondria. By contrast, 2-phenyl-3-nitroso-imidazo[1,2-a]pyrimidine acted as a DNA poison, causing damage to the nuclear DNA and inducing mutagenesis. We compared compound 15 to known chemotherapeutics and found resistance required intact DNA repair pathways. Thus, subtle changes in the structure of imidazo-pyridines and -pyrimidines dramatically alter both the intracellular targeting of these compounds and their effects in vivo. Of particular interest, these different modes of action were evident in experiments on human cells, suggesting that chemical–genetic profiles obtained in yeast are recapitulated in cultured cells, indicating that our observations in yeast can: (1) be leveraged to determine mechanism of action in mammalian cells and (2) suggest novel structure–activity relationships.     

Sleep-related daytime consequences mediated the neuroticism–depression link

Sleep and Biological Rhythms - Neuroticism has been found to predispose individuals to depression, but the underlying mechanism is not well studied. The current study sought to delineate the...     

Tracking Public Beliefs About Anthropogenic Climate Change

A simple question about climate change, with one choice designed to match consensus statements by scientists, was asked on 35 US nationwide, single-state or regional surveys from 2010 to 2015. Analysis of these data (over 28,000 interviews) yields robust and exceptionally well replicated findings on public beliefs about anthropogenic climate change, including regional variations, change over time, demographic bases, and the interacting effects of respondent education and political views. We find that more than half of the US public accepts the scientific consensus that climate change is happening now, caused mainly by human activities. A sizable, politically opposite minority (about 30 to 40%) concede the fact of climate change, but believe it has mainly natural causes. Few (about 10 to 15%) say they believe climate is not changing, or express no opinion. The overall proportions appear relatively stable nationwide, but exhibit place-to-place variations. Detailed analysis of 21 consecutive surveys within one fairly representative state (New Hampshire) finds a mild but statistically significant rise in agreement with the scientific consensus over 2010–2015. Effects from daily temperature are detectable but minor. Hurricane Sandy, which brushed New Hampshire but caused no disaster there, shows no lasting impact on that state’s time series—suggesting that non-immediate weather disasters have limited effects. In all datasets political orientation dominates among individual-level predictors of climate beliefs, moderating the otherwise positive effects from education. Acceptance of anthropogenic climate change rises with education among Democrats and Independents, but not so among Republicans. The continuing series of surveys provides a baseline for tracking how future scientific, political, socioeconomic or climate developments impact public acceptance of the scientific consensus.     

Effect of Temperature, Light, Nutrients and Dehardening on Abscisic Acid Induced Cold Hardiness in Bromus inermis Leyss Suspension Cultured Cells

The effects of culture conditions on abscisic acid (ABA)-inducedfreezing tolerance were determined in smooth bromegrass Bromusinermis Leyss cv. Manchar) cell suspension cultures. Bromegrasscultures initiated with 2 g fr wt of cells achieved maximumfreezing tolerances (greater than –32?C) at 25 to 30?Cin the presence of 75 to 100 µM ABA. High levels of freezingtolerance induced by ABA were correlated with high growth ratesat 25 and 30?C. In control cells, incubation at 10?C inducedoptimum levels of hardiness with minimal growth. Prolonged exposure(6 weeks) of cells to 3?C, with or without ABA, increased freezingtolerance only by several degrees. Exogenous ABA concentrationsgreater than 100 µM were not inhibitory to growth. Repeatedexposure to ABA, however, retarded growth and made the cellstolerant to temperatures below –40?C. Removal of ABA fromthe medium resulted in dehardening of the cells both at 25 and3?C. Nitrogen had a marginal effect on ABA-induced hardeningat 25?C, but inhibited age-dependent hardening of control cellcultures. Light had no effect on the freezing tolerance of culturedcells. Addition of 10% sucrose, 30 min prior to freezing, tobromegrass cells treated with ABA for 4 days increased freezingtolerance more than 15?C. These observations are discussed inrelation to the contrasting behaviour of the low temperatureand photoperiod dependent cold acclimation of plants (Received July 14, 1989; Accepted October 23, 1989)     

Skeletal and muscular pelvic morphology of hillstream loaches (Cypriniformes: Balitoridae)

The rheophilic hillstream loaches (Balitoridae) of South and Southeast Asia possess a range of pelvic girdle morphologies, which may be attributed to adaptations for locomotion against rapidly flowing water. Specifically, the connectivity of the pelvic plate (basipterygium) to the vertebral column via a sacral rib, and the relative size and shape of the sacral rib, fall within a spectrum of three discrete morphotypes: long, narrow rib that meets the basipterygium; thicker, slightly curved rib meeting the basipterygium; and robust crested rib interlocking with the basipterygium. Species in this third category with more robust sacral rib connections between the basipterygium and vertebral column are capable of walking out of water with a tetrapod-like lateral-sequence, diagonal-couplet gait. This behavior has not been observed in species lacking direct skeletal connection between the vertebrae and the pelvis. The phylogenetic positions of the morphotypes were visualized by matching the morphological features onto a novel hypothesis of relationships for the family Balitoridae. The morphotypes determined through skeletal morphology were correlated with patterns observed in the pelvic muscle morphology of these fishes. Transitions towards increasingly robust pelvic girdle attachment were coincident with a more anterior origin on the basipterygium and more lateral insertion of the muscles on the fin rays, along with a reduction of the superficial abductors and adductors with more posterior insertions. These modifications are expected to provide a mechanical advantage for generating force against the ground. Inclusion of the enigmatic cave-adapted balitorid Cryptotora thamicola into the most data-rich balitorid phylogeny reveals its closest relatives, providing insight into the origin of the skeletal connection between the axial skeleton and basipterygium.     

Cellular resistance to the antimelanoma immunotoxin ZME-gelonin and strategies to target resistant cells

 The development of cellular resistance to immunotoxins has been demonstrated in a variety of models and can involve a number of mechanisms. For the present study, an immunotoxin was utilized composed of an antimelanoma antibody ZME-018 recognizing a 240-kDa surface glycoprotein (gp 240) and the plant toxin gelonin. Human melanoma cells (A375-M) were grown in the presence of increasing amounts of ZME-gelonin and a clonal variant (A-375-ZR) was developed that was 100-fold resistant to ZME-gelonin compared to parental cells. Scatchard analysis showed that the A375-M parental cells had 260×10³ ZME-gelonin-binding sites/cell with relatively low affinity (5 nM). In contrast, resistant A375-ZR cells demonstrated a reduced number of low-affinity sites (160×10³/cell), but showed a small number (47×10³) of higher-affinity sites (0.8 nM). Internalization rates and degradation rates of ¹²⁵I-labeled ZME-gelonin were identical in both the parental and resistant cells. A375-ZR cells were found to be more resistant to vincristine and doxorubicin than were parental cells. Both cell lines were almost equally sensitive to native gelonin, 5-fluorouracil (5-FU), cisplatin, melphalan, carmustine, interferon γ (IFNγ) and IFNα. In addition, both cell lines were equally sensitive to another gelonin-antibody conjugate that binds to cell-surface, GD₂ (antibody 14G₂A). However, resistant cells were twice as sensitive to the cytotoxic effects of etoposide than were parental cells. Finally, a variety of agents were tested in combination with ZME-gelonin against A375-ZR cells in an attempt to identify agents to augment immunotoxin cytotoxic effects against resistant cells. The agents 5-FU, cisplatin, IFNγ, IFNα, and etoposide were the most effective in augmenting the cytotoxicity of ZME-gelonin against resistant cells. These studies suggest that development of resistance to one immunotoxin does not cause development of cross-resistance to other gelonin immunotoxins. Further, specific biological response modifiers and chemotherapeutic agents may be effective in augmenting the effectiveness of immunotoxins and specifically targeting or reducing the emergence of immunotoxin-resistant cells. Received: 15 March 1995 / Accepted: 28 November 1995     

A doubly auxotrophic CHO-K1 cell line for the production of recombinant monoclonal antibodies

Chinese hamster ovary (CHO) cells are the most widely used mammalian hosts for recombinant protein production due to their hardiness, ease of transfection, and production of glycan structures similar to those in natural human monoclonal antibodies. To enhance the usefulness of CHO-K1 cells we developed a new selection system based on double auxotrophy. We used CRISPR-Cas9 to knockout the genes that encode the bifunctional enzymes catalyzing the last two steps in the de novo synthesis of pyrimidines and purines (uridine monophosphate synthase and 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase [ATIC], respectively). Survival of these doubly auxotrophic cells depends on the provision of sources of purines and pyrimidines or on the transfection and integration of open reading frames encoding these two enzymes. We successfully used one such double auxotroph (UA10) to select for stable transfectants carrying (a) the recombinant tumor necrosis factor-α receptor fusion protein etanercept and (b) the heavy and light chains of the anti-Her2 monoclonal antibody trastuzumab. Transfectant clones produced these recombinant proteins in a stable manner and in substantial amounts. The availability of this double auxotroph provides a rapid and efficient selection method for the serial or simultaneous transfer of genes for multiple polypeptides of choice into CHO cells using readily available purine- and pyrimidine-free commercial media.