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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.  相似文献   
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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)  相似文献   
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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.  相似文献   
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 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  相似文献   
6.
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.  相似文献   
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The complex nuclear structure of somatic cells is important to epigenomic regulation, yet little is known about nuclear organization of human embryonic stem cells (hESC). Here we surveyed several nuclear structures in pluripotent and transitioning hESC. Observations of centromeres, telomeres, SC35 speckles, Cajal Bodies, lamin A/C and emerin, nuclear shape and size demonstrate a very different “nuclear landscape” in hESC. This landscape is remodeled during a brief transitional window, concomitant with or just prior to differentiation onset. Notably, hESC initially contain abundant signal for spliceosome assembly factor, SC35, but lack discrete SC35 domains; these form as cells begin to specialize, likely reflecting cell‐type specific genomic organization. Concomitantly, nuclear size increases and shape changes as lamin A/C and emerin incorporate into the lamina. During this brief window, hESC exhibit dramatically different PML‐defined structures, which in somatic cells are linked to gene regulation and cancer. Unlike the numerous, spherical somatic PML bodies, hES cells often display ~1–3 large PML structures of two morphological types: long linear “rods” or elaborate “rosettes”, which lack substantial SUMO‐1, Daxx, and Sp100. These occur primarily between Day 0–2 of differentiation and become rare thereafter. PML rods may be “taut” between other structures, such as centromeres, but clearly show some relationship with the lamina, where PML often abuts or fills a “gap” in early lamin A/C staining. Findings demonstrate that pluripotent hES cells have a markedly different overall nuclear architecture, remodeling of which is linked to early epigenomic programming and involves formation of unique PML‐defined structures. J. Cell. Biochem. 107: 609–621, 2009. © 2009 Wiley‐Liss, Inc.  相似文献   
10.
The plumula is enclosed by a single layer of epithelial cells. There are two types of odontoblasts: syncytial and free odontoblasts. Syncytial odontoblasts are arranged linearly on the abaxial side and have a highly active Golgi complex, rough endoplasmic reticulum, large and round mitochondria, and small coated vesicles indicative of a high level of secretory activity. Free odontoblasts cluster on the adaxial side and have patchy chromatin and little cytoplasm. The free odontoblasts migrate to the abaxial side, where their structure changes to that of syncytial odontoblasts. Calcareous deposits are formed intracellularly by syncytial odontoblasts within two membranes: an outer plasma membrane and an inner vacuolar membrane. The vacuolar membrane has organic particles on the surface of the membrane. There is no trace of organic matter within the calcareous deposit. Fibroblasts are located on the adaxial side. Collagen fibers are located primarily on the adaxial side adjacent to the calcareous depositing membranes and between free odontoblasts, but they are not located in the deposits. Collagen fibers may play a role in cell migration and thus in calcification. The morphological changes of the plumulae are closely related to calcification.  相似文献   
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