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941.
Climate change‐induced warming and ocean acidification are considered two imminent threats to marine biodiversity and current ecosystem structures. Here, we have for the first time examined an animal's response to a complete life cycle of exposure to co‐occurring warming (+3°C) and ocean acidification (+1,600 μatm CO2), using the key subarctic planktonic copepod, Calanus finmarchicus, as a model species. The animals were generally negatively affected by warming, which significantly reduced the females’ energy status and reproductive parameters (respectively, 95% and 69%–87% vs. control). Unexpectedly, simultaneous acidification partially offset the negative effect of warming in an antagonistic manner, significantly improving reproductive parameters and hatching success (233%–340% improvement vs. single warming exposure). The results provide proof of concept that ocean acidification may partially offset negative effects caused by warming in some species. Possible explanations and ecological implications for the observed antagonistic effect are discussed. 相似文献
942.
Madoka Hashido Francis K. Lee Andre J. Nahmias Takashi Kawana 《Microbiology and immunology》1997,41(10):823-827
Sixty-eight sera from the acute, recurrent, and provoked types of female genital herpes were compared for the seroprevalence of herpes simplex virus (HSV) types 1 and 2 by immunodot assay using HSV glycoprotein G. In the HSV-1-isolated patients, no HSV-2 antibodies were detected, whereas in the HSV-2-isolated patients, HSV-1 seroprevalence was 9% for the acute type, 89% for the provoked type (P< 0.005), and 55% for the recurrent type (P<0.05). The natural history of female genital herpes and the possible protective role of pre-existing antibodies in preventing the acquisition or clinical manifestation of a subsequent HSV infection are discussed. 相似文献
943.
Microheterogeneity of the oligosaccharides carried by the recombinant bovine lactoferrin expressed in Mamestra brassicae cells 总被引:1,自引:0,他引:1
Lopez Michel; Coddeville Bernadette; Langridge James; Plancke Yves; Sautiere Pierre; Chaabihi Hassan; Chirat Frederic; Harduin-Lepers Anne; Cerutti Martine; Verbert Andre; Delannoy Philippe 《Glycobiology》1997,7(5):635-651
The development of therapeutic glycoprotein production usingthe baculovirus expression system depends on the ability ofinsect cell lines to reproduce site specific mammalian-likeN-glycans. A combination of 1H-NMR and mass spectrometry techniques(MALD-MS, ES-MS, and CID-MS-MS) allowed us to elucidate theN-linked oligosaccharides microheterogeneity on three differentN-glycosylation sites, Asn233, Asn476, and Asn545, of a baculovirus-expressedrecombinant bovine lactoferrin produced in Mamestra brassicae.Two families of N-glycan structures have been found: first,oligomannosidic glycans (Man95GlcNAC2) and secondly, short truncatedpartially fucosylated glycans (Man32[Fuc01]GlcNAc2).These results indicate that Mamestra brassicae cell line isnot able to synthesize complex N-glycans, even if an 相似文献
944.
Acute and chronic effects of exercise on leptin levels in humans 总被引:8,自引:0,他引:8
Perusse Louis; Collier Gregory; Gagnon Jacques; Leon Arthur S.; Rao D. C.; Skinner James S.; Wilmore Jack H.; Nadeau Andre; Zimmet Paul Z.; Bouchard Claude 《Journal of applied physiology》1997,83(1):5-10
Pérusse, Louis, Gregory Collier, Jacques Gagnon,Arthur S. Leon, D. C. Rao, James S. Skinner, Jack H. Wilmore,André Nadeau, Paul Z. Zimmet, and Claude Bouchard. Acute andchronic effects of exercise on leptin levels in humans.J. Appl. Physiol. 83(1): 5-10, 1997.The acute (single bout of exercise) and chronic (exercisetraining) effects of exercise on plasma leptin were investigated in 97 sedentary adult men (n = 51) and women(n = 46) participating in the HERITAGEFamily Study. Exercise training consisted of a standardized 20-wkendurance training program performed in the laboratory on acomputer-controlled cycle ergometer. Maximal oxygen uptake, bodycomposition assessed by hydrostatic weighing, and fasting insulin levelwere also measured before and after training. Pre- and posttrainingblood samples were obtained before and after completion of a maximalexercise test on the cycle ergometer. Exercise training resulted insignificant changes in maximal oxygen uptake (increase in both genders)and body compostion (reduction of fat mass in men and increase infat-free mass in women). There were considerable interindividualdifferences in the leptin response to acute and chronic effects ofexercise, some individuals showing either increase or reduction inleptin, others showing almost no change. On average, leptin levels werenot acutely affected by exercise. After endurance training wascompleted, leptin levels decreased significantly in men (from 4.6 to3.9 ng/ml; P = 0.004) but not inwomen. However, after the training-induced changes in body fat masswere accounted for, the effects of exercise training were no longersignificant. Most of the variation observed in leptin levels afteracute exercise or endurance training appears to be within theconfidence intervals of the leptin assay. We conclude that there are nomeaningful acute or chronic effects of exercise, independent of theamount of body fat, on leptin levels in humans. 相似文献
945.
We have cloned DNA fragments of plasmid pFL40 from Alcaligenes xylosoxidans ssp. denitrificans ABIV encoding a D,L-2-haloalkanoic acid halidohydrolase (DhlIV). A 6.5-kb EcoRI/SalI-fragment with inducible expression of the halidohydrolase was cloned in Pseudomonas fluorescens and Escherichia coli. A 1.9-kb HindII-fragment demonstrated expression of the dehalogenase only due to the presence of the promoter from the pUC vector in Escherichia coli. The nucleotide sequence of this DNA-fragment was determined. It had an open reading frame coding for 296 amino acid residues (molecular weight of 32783 D). The dhlIV gene showed sequence homology to a short segment of a D-specific dehalogenase (hadD) from Pseudomonas putida AJ1, but not to any other known DNA sequences. Restriction enzyme patterns indicated similarity between dhlIV and the D,L-isomer specific dehI dehalogenase gene from Pseudomonas putida PP3. There are some indications from restriction enzyme patterns and initial sequencing data, that a gene encoding a 54 activator protein, similar to the dehR
Iregulatory gene from Pseudomonas putida PP3 is located upstream of dhlIV. In contrast to DehI, dehalogenation of D-or L-chloropropionic acid by the DhlIV-protein leads to lactic acid of inverted configuration. 相似文献
946.
Philippe Delannoy Isabelle Kim Nathalie Emery Carmen de Bolos Andre Verbert Pierre Degand Guillemette Huet 《Glycoconjugate journal》1996,13(5):717-726
We have analysed the mucins synthesized by the HT-29 MTX cell subpopulation, derived from the HT-29 human colon carcinoma cells through a selective pressure with methotrexate (Lesuffleuret al., 1990,Cancer Res
50: 6334–43), in the presence of benzyl-N-acetyl--galactosaminide (GalNAc-O-benzyl), which is a potential competitive inhibitor of the 1,3-galactosyltransferase that synthesizes the T-antigen. The main observation was a 13-fold decrease in the sialic acid content of mucins after 24 h of exposure to 5mm GalNAc-O-benzyl. This effect was accompanied by an increased reactivity of these mucins to peanut lectin, testifying to the higher amount of T-antigen. The second observation was a decrease in the secretion of the mucins by GalNAc-O-benzyl treated cells. The decrease in mucin sialyation was achieved through thein situ -galactosylation of GalNAc-O-benzyl into Gal1–3GalNAc-O-benzyl, which acts as a competitive substrate of Gal1–3GalNAc 2,3-sialyltransferase, as shown by the intracellular accumulation of NeuAc2–3Gal1–3GalNAc-O-benzyl in treated cells.Abbreviations BSM
bovine submaxillary mucin
- MTX
methotrexate
- PBS
sodium phosphate 10mm, NaCl 0.15m, pH 7.4 buffer
-
pNp
p-nitrophenol
- TBS
Tris/HCl 10mm, NaCl 0.15m, pH 7.4 buffer
Enzymes: CMP-NeuAc: Gal1–3/4GlcNAc 2,3-sialyltransferase, ST3(N), EC 2.4.99.6; CMP-NeuAc: Gal1–4GlcNAc 2,6-sialyltransferase, ST6(N), EC 2.4.99.1; CMP-NeuAc: Gal1–3GalNAc 2,3-sialyltransferase, ST3(O), EC 2.4.99.4; CMP-NeuAc: R-GalNAc1-O-Ser 2,6-sialyltransferase, ST6(O)-I, EC 2.4.99.3; CMP-NeuAc: NeuAc2–3Gal1–3GalNAc 2,6-sialyltransferase, ST6(O)-II, EC 2.4.99.7; UDP-GlcNAc: Gal1–3GalNAc-R·(GlcNAc to GalNAc) 1,6-N-acetylglucosaminyltransferase, EC 2.4.1.102; UDP-GlcNAc: GalNAc-R 1,3-N-acetylglucosaminyltransferase, EC 2.4.1.147; UDP-Gal: GalNAc-R 1,3-galactosyltransferase, EC 2.4.1.122. 相似文献
947.
William S. C. Gurney David A. J. Middleton Roger M. Nisbet Edward McCauley William W. Murdoch Andre DeRoos 《Theoretical population biology》1996,49(3):344-368
This paper considers the relationship between the demographic mechanisms of population control and the energetics of the individuals who comprise the population. We examine the equilibrium properties of a class of structured population models in which individuals compete for some environmental resource (such as food) and demonstrate that population demography is independent of the nature of the feedback loop which establishes the equilibrium state. We thus derive general insights into the influence exerted by individual energetic and allocation strategies on population average demographic characteristics. We show that models of individual energetics which produce apparently very similar predictions at the individual level can result in very different behaviour at the population level. In addition, we observe that different models of individual mortality can imply marked differences in population demography and that the common assumption of constant mortality can be responsible for potentially unrealistic model behaviour. Our results emphasise the substantial data requirements for parameterising and testing individual-based models. 相似文献
948.
949.
The relationship among impaired selenium status, lipid peroxidation, and liver function was examined in 19 hospitalized patients with severe alcoholic cirrhosis. Plasma selenium was found to be significantly lower (mean±SD: 54±13 μg/L) than in healthy controls (83±11 μg/L) and plasma malondialdehyde, assessed as thiobarbituric acid reactants, which reflects lipid peroxidation, was increased (2.0±1.2 μmol/L vs <1.2 μmol/L in controls). The mean14C aminopyrine breath test, an indicator of liver function, was lower than normal (2.7±1.9 vs 6.3±0.9% in controls) and found to be significantly correlated with plasma selenium (r=0.59,p<0.05). A prospective, randomized selenium supplementation trial was conducted in a group of 16 patients who received either daily 100 μg selenium as enriched yeast during 4 mo or a placebo. Among the 10 patients who completed the study, plasma selenium significantly increased in the supplemented group (n=4; before: 58±10 μg/L, and after 101±12 μg/L,p<0.01) contrary to the placebo group (n=6, before: 47±10 μg/L, after: 57±9 μg/L, n.s.),14C aminopyrine breath test improved in three out of four selenium-supplemented patients and in three out of six placebo patients, but the small number of patients did not allow statistical evaluation. These results demonstrate that low selenium status in alcoholic cirrhosis is correlated to liver function and could be improved by supplementation. 相似文献
950.
Jakobsen Hans Henrik; Halvorsen Elisabeth; Hansen Benni Winding; Visser Andre W. 《Journal of plankton research》2005,27(8):775-785
Feeding experiments were conducted with the ambush-feeding copepodAcartia tonsa and the feeding-current-generating copepod Temoralongicornis. The copepods were offered a mixed diet of the dinoflagellateHeterocapsa triquetra and the ciliate Balanion comatum of similarcell size. The dinoflagellate was offered at a constant concentrationof 1015 cells mL1, whereas the ciliate was offeredat a variety of concentrations, ranging from 7 to 57 cells mL1.Copepods with different feeding modes possess different mechanismsfor prey detection, suggesting that the two copepods would responddifferently to the two prey types. Both copepods had significantlyhigher clearance rates on the highly motile ciliate than onthe less motile dinoflagellate. In encounters between A. tonsaand its prey, we argue that this is due to the higher hydromechanicalsignal generated by the ciliate. The advection feeding copepodT. longicornis fed on the two prey according to their relativeconcentrations; in this case, we suggest that although B. comatumis capable of detecting feeding-current-generating predators,the feeding current velocity generated by T. longicornis isgreater than the escape velocity of this ciliate. 相似文献