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141.
ABSTRACT Distress calls are signals effective over a long distance. They are well known to evoke interspecific reactions. We suggest that the interspecificity phenomenon results from the use of similar laws of decoding by the species concerned. These laws must take into account the transmission channel which always has a great influence on long-range communication. We tested our hypothesis by broadcasting simplified synthetic calls to two species of birds: the herring gull and the starling. The various calls differed in terms of frequency modulation (FM). Two main conclusions emerged from this series of tests: 1. The parameters used for recognition are not sophisticated: a simple slope applied to a carrier frequency that corresponds to the acoustic shape of a distress call is sufficient to confer a distress meaning to the signal. The basic rules are the same for the gull and the starling, with differences only in the acceptance level of the species. 2. The system of recognition is based upon parameters not altered by the environment: the birds make use of the slow frequency modulations (FMI). In contrast, the fast frequency sweeps (FMII) which are modified during propagation do not seem to be utilised. The use of these characteristics of distress calls for recognition allows interspecificity and maximum efficiency for propagation over long distances.
RESUME
Une particularité des cris de détresse est leur action interspécifique. Nous suggérons que cette interspécificité résulte de l'emploi d'une loi de décodage qui est commune à plusieures espèces. Cette loi doit tenir compte des propriétés du canal car ce dernier a toujours une grande influence sur les signaux de longue portée acoustique, tels que les cris de détresse. Pour tester cette hypothèse, nous avons fait appel à deux espèces: le Goéland argenté (Larus argentatus) et l'Etourneau (Sturnus vulgaris). Les signaux que nous avons diffusés étaient obtenus par synthèse. Ils étaient plus simples que les signaux naturels et différaient par la modulation de fréquence (FM). Deux résultats principaux émergent de ces séries d'expériences: 1. Le procédé de décodage n'est pas sophistiqué: une simple pente appliquée à la porteuse est nécessaire et il suffit de mimer, meme approximativement, la pente rencontrée dans les signaux naturels, Cette règle fondamentale est commune au Goéland et à l'Etourneau. Les petites différences que l'on peut néanmoins observer sont relatives aux seuils de décodage. 2. Le décodage repose sur des paramètres qui ne sont pas altérés par le canal: l'oiseau utilise la modulation lente de fréquence. Par contre les excursions rapides de fréquence semblent n'étre d'aucune utilité lors du décodage. En conclusion, l'universalité des paramètres impliqués et de la loi de décodage est responsable de l'interspécificité des signaux de détresse. Les simplifications liées à cette universalité résultent des contraintes imposées par le canal. 相似文献
142.
Methicillin-resistant Staphylococcus aureus (MRSA) poses a serious problem in dairy animals suffering from mastitis. In the present study, the distribution of mastitic
MRSA and antibiotic resistance was studied in 107 strains of S. aureus isolated from milk samples from 195 infected udders. The characterizations pathogenic factors (adhesin and toxin genes) and
antibiotic susceptibility of isolates were carried out using gene amplification and disc diffusion assays, respectively. A
high prevalence of MRSA was observed in the tested isolates (13.1%). The isolates were also highly resistant to antibiotics,
i.e. 36.4% were resistant to streptomycin, 33.6% to oxytetracycline, 29.9% to gentamicin and 26.2% each to chloramphenicol,
pristinomycin and ciprofloxacin. A significant variation in the expression of pathogenic factors (Ig, coa and clf) was observed in these isolates. The overall distribution of adhesin genes ebp, fib, bbp, fnbB, cap5, cap8, map and cna in the isolates was found to be 69.1, 67.2, 6.5, 20.5, 60.7, 26.1, 81.3 and 8.4%, respectively. The presence of fib, fnbB, bbp and map genes was considerably greater in MRSA than in methicillin-susceptible S. aureus (MSSA) isolates. The proportions of toxin genes, namely, hlb, seb, sec, sed, seg and sei, in the isolates were found to be 94.3, 0.9, 8.4, 0.9, 10.2 and 49.5%, respectively. The proportions of agr genes I, II, III and IV were found to be 39.2, 27.1, 21.5 and 12.1%, respectively. A few isolates showed similar antibiotic-resistance
patterns, which could be due to identical strains or the dissemination of the same strains among animals. These findings can
be utilized in mastitis treatment programmes and antimicrobials strategies in organized herds. 相似文献
143.
Nonalcoholic fatty liver disease (NAFLD) represents a burgeoning public health concern in westernized nations. The obesity-related disorder is associated with an increased risk of cardiovascular disease, type 2 diabetes and liver failure. Although the underlying pathogenesis of NAFLD is unclear, increasing evidence suggests that excess saturated fatty acids presented to or stored within the liver may play a role in both the development and progression of the disorder. A putative mechanism linking saturated fatty acids to NAFLD may be endoplasmic reticulum (ER) stress. Specifically, excess saturated fatty acids may induce an ER stress response that, if left unabated, can activate stress signaling pathways, cause hepatocyte cell death, and eventually lead to liver dysfunction. In the current review we discuss the involvement of saturated fatty acids in the pathogenesis of NAFLD with particular emphasis on the role of ER stress. 相似文献
144.
Annual methane uptake by temperate semiarid steppes as regulated by stocking rates,aboveground plant biomass and topsoil air permeability 总被引:1,自引:0,他引:1
WEIWEI CHEN BENJAMIN WOLF XUNHUA ZHENG ZHISHENG YAO KLAUS BUTTERBACH‐BAHL NICOLAS BRÜGGEMANN CHUNYAN LIU SHENGHUI HAN XINGGUO HAN 《Global Change Biology》2011,17(9):2803-2816
Overgrazing‐induced degradation of temperate semiarid steppes may affect the soil sink for atmospheric methane (CH4). However, previous studies have primarily focused on the growing season and on single grazing patterns. Thus, the response of annual CH4 uptake by steppes compared with various grazing practices is uncertain. In this study, we investigated the effects of grazing on the annual CH4 uptake by two typical Eurasian semiarid steppes (the Stipa grandis steppe and the Leymus chinensis steppe) located in Inner Mongolia, China. The CH4 fluxes were measured year‐round using static chambers and gas chromatography at 12 field sites that differed primarily in grazing intensities. Our results indicated that steppe soils were CH4 sinks throughout the year. The annual CH4 uptake correlated with stocking rates, whereas the seasonality of CH4 uptake was primarily dominated by temperature. The annual CH4 uptake at all sites averaged 3.7±0.7 kg C ha?1 yr?1 (range: 2.3–4.5), where approximately 35% (range: 23–40%) occurred during the nongrowing season. Light‐to‐moderate grazing (stocking rate≤1 sheep ha?1 yr?1) did not significantly change the annual CH4 uptake compared with ungrazed steppes, but heavy grazing reduced annual CH4 uptake significantly (by 24–31%, P<0.05). These findings imply that easing the pressure of heavily grazed steppes (e.g. moving to light or moderate stocking rates) would help restore steppe soil sinks for atmospheric CH4. The empirical equations based on the significant relationships between annual CH4 uptake and stocking rates, aboveground plant biomass and topsoil air permeability (P<0.01) could provide simple approaches for the estimation of regional CH4 uptake by temperate semiarid steppes. 相似文献
145.
146.
ABSTRACT: UV cross-linking and immunoprecipitation (CLIP) and individual-nucleotide resolution CLIP (iCLIP) are methods to study protein-RNA interactions in untreated cells and tissues. Here, we analyzed six published and two novel data sets to confirm that both methods identify protein-RNA cross-link sites, and to identify a slight uridine preference of UV-C-induced cross-linking. Comparing Nova CLIP and iCLIP data revealed that cDNA deletions have a preference for TTT motifs, whereas iCLIP cDNA truncations are more likely to identify clusters of YCAY motifs as the primary Nova binding sites. In conclusion, we demonstrate how each method impacts the analysis of protein-RNA binding specificity. 相似文献
147.
NICOLAS GOUDEMAND MICHAEL J. ORCHARD PAUL TAFFOREAU SEVERINE URDY THOMAS BRÜHWILER ARNAUD BRAYARD THOMAS GALFETTI HUGO BUCHER 《Palaeontology》2012,55(5):1021-1034
Abstract: Several fused clusters of conodont elements of the genera Neospathodus and Novispathodus were recovered from limestone beds at the Dienerian–Smithian and Smithian–Spathian boundaries, respectively, from several localities in Guangxi province, South China. Conodont clusters are otherwise extremely rare in the Triassic, and these are first described for the Early Triassic. The exceptional specimens partially preserve the relative three‐dimensional position and orientation of ramiform elements and are therefore extremely important for testing hypotheses on the architecture of apparatuses. These specimens partly confirm the previous reconstruction of the Novispathodus apparatus by Orchard. Within apparatuses of members of superfamily Gondolelloidea, elements previously identified as occupying the S1 and S2 positions instead occupy the S2 and S1 positions. Similarly, within apparatuses of members of the subfamily Novispathodinae, elements previously referred to S3 and S4 positions are reinterpreted to have occupied S4 and S3 positions, respectively. 相似文献
148.
149.
Gerd N. La Mar John Del Gaudio James S. Frye 《Biochimica et Biophysica Acta (BBA)/General Subjects》1977,498(2):422-435
The proton NMR spectra of a series of low-spin bis-cyano ferric complexes of tetraarylporphyrins and octaethylporphyrin in a variety of solvents have been recorded and analyzed. The hyperfine shifts are shown to be very sensitive to the solvent, experiencing an overall downfield bias as the solvent hydroge-bonding donor strength increased. The characteristic pattern of the contact and dipolar shifts for the meso-aryl group in tetraarylporphyrin complexes are shown to permit a quantitative separation of the dipolar and contact contributions to the hyperfine shift. The separated components indicate that increased solvent hydrogen bonding strength significantly decreases the magnetic anisotropy of the iron and diminishes porphyrin → iron π bonding. The changes in anisotropy with solvent are shown to be consistent with the coordinated cyanide acting as a proton acceptor. Although similar effects are found to be absent in bis-imidazole complexes, a downfield bias of half the magnitude of the bis-cyano complexes is observed in mixed cyano/imidazole complexes. Hence, the heme hyperfine shifts in cyano-metmyoglobins and -hemoglobins may serve as probes for the protonation of the distal histidyl imidazole. 相似文献
150.
Bioreactor scale up and protein product quality characterization of piggyBac transposon derived CHO pools
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Robert B. Peery James R. Swartling Neil A. McCracken Dawn L. Norris Christopher C. Frye Gavin C. Barnard 《Biotechnology progress》2017,33(2):534-540
Chinese hamster ovary (CHO) cells remain the most popular host for the production of biopharmaceutical drugs, particularly monoclonal antibodies (mAbs), bispecific antibodies, and Fc‐fusion proteins. Creating and characterizing the stable CHO clonally‐derived cell lines (CDCLs) needed to manufacture these therapeutic proteins is a lengthy and laborious process. Therefore, CHO pools have increasingly been used to rapidly produce protein to support and enable preclinical drug development. We recently described the generation of CHO pools yielding mAb titers as high as 7.6 g/L in a 16 day bioprocess using piggyBac transposon‐mediated gene integration. In this study, we wanted to understand why the piggyBac pool titers were significantly higher (2–10 fold) than the control CHO pools. Higher titers were the result of a combination of increased average gene copy number, significantly higher messenger RNA levels and the homogeneity (i.e. less diverse population distribution) of the piggyBac pools, relative to the control pools. In order to validate the use of piggyBac pools to support preclinical drug development, we then performed an in‐depth product quality analysis of purified protein. The product quality of protein obtained from the piggyBac pools was very similar to the product quality profile of protein obtained from the control pools. Finally, we demonstrated the scalability of these pools from shake flasks to 36L bioreactors. Overall, these results suggest that gram quantities of therapeutic protein can be rapidly obtained from piggyBac CHO pools without significantly changing product quality attributes. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:534–540, 2017 相似文献