Abrupt temperature changes in the Western Mediterranean over the past 250,000 years     

Martrat B  Grimalt JO  Lopez-Martinez C  Cacho I  Sierro FJ  Flores JA  Zahn R  Canals M  Curtis JH  Hodell DA 《Science (New York, N.Y.)》2004,306(5702):1762-1765

A continuous high-resolution Western Mediterranean sea surface temperature (SST) alkenone record spanning the past 250,000 years shows that abrupt changes were more common at warming than at cooling. During marine isotope stage (MIS) 6, SST oscillated following a stadial-interstadial pattern but at lower intensities and rates of change than in the Dansgaard/Oeschger events of MIS 3. Some of the most prominent events occurred over MISs 5 and 7, after prolonged warm periods of high stability. Climate during the whole period was predominantly maintained in interglacial-interstadial conditions, whereas the duration of stadials was much shorter.  相似文献   

Block Estimating of Spatial Yield Data and its Uncertainty     

Han  Shufeng  Schneider  Sally M.  Evans  Robert G.  Davenport  Joan R. 《Precision Agriculture》2004,5(1):73-84

On-the-go yield monitors have been available for both grain and bulk crops. Most of the yield monitors today provide yield measurement at a fixed time interval. Conversion of these point yield data into raster yield maps for further analysis is necessary. In this study, a data-blocking procedure is proposed to create raster yield maps from point yield data. The blocking procedure includes: (1) converting the fixed-time-interval data into fixed-distance-interval data; (2) using a moving average algorithm to estimate a cell value when there are sufficient data points within the cell; (3) using a geostatistical algorithm to estimate a cell value when there are not enough data points within the cell but values of its neighboring cells are known; and (4) calculating an uncertainty index for each cell value estimation. An example application of the yield-blocking procedure with potato harvest data in 1996 was given.  相似文献   

Marine fish egg hydration is aquaporin-mediated     

Fabra M  Raldúa D  Power DM  Deen PM  Cerdà J 《Science (New York, N.Y.)》2005,307(5709):545

The positive buoyancy of marine fish eggs in sea water, allowed by hydration of the oocyte, is critical for their survival and dispersion in the ocean. We isolated an aquaporin, SaAQP1o, that belongs to a unique subfamily of aquaporin-1-like channels specifically evolved in teleosts and mainly expressed in the ovary. We further show that hormone-induced fish oocyte hydration is a highly controlled process based on the interplay between protein hydrolysis and the translocation of SaAQP1o to the plasma membrane, indicating a specialized physiological role for this aquaporin.  相似文献   

Tissue-specific enhancement of xenobiotic detoxification enzymes in mice by dietary rosemary extract     

Keith W. Singletary  Joan T. Rokusek 《Plant foods for human nutrition (Dordrecht, Netherlands)》1997,50(1):47-53

Plant foods contain nutritive and minor, nonnutritive components capable of inhibiting experimental carcinogenesis. Many of these cancer-protective extracts act by enhancing the activities of enzymes that can detoxify reactive substances. In the present study an extract of the spice plant rosemary was fed at concentrations of 0.3% and 0.6% (by weight) for 4 weeks to female A/J mice prior to determination of the activities of the detoxification enzymes glutathione-S-transferase (GST) and NAD(P)H: quinone reductase (QR) in lung, liver and stomach. Liver activities of GST and QR, and stomach GST activity were significantly increased in animals fed diets containing rosemary extract. However, diets supplemented with rosemary extract did not affect lung GST and QR activities. These results indicate that components of rosemary extract have the potential to protect mouse liver and stomach from carcinogenic or toxic agents.  相似文献   

Validation of a food-frequency questionnaire for measurement of nutrient intake in a dietary intervention study     

Segovia-Siapco G  Singh P  Jaceldo-Siegl K  Sabaté J 《Public health nutrition》2007,10(2):177-184

OBJECTIVE: To validate a 171-item semi-quantitative food-frequency questionnaire (FFQ) for measurement of nutrient intake in an intervention trial based on walnut supplementation. DESIGN AND SETTING: Free-living adults from Southern California were randomly assigned to either an intervention (walnut-supplemented) or a control diet. The prescribed 6-month intervention was > or = 28 g of walnuts per day for the walnut-supplemented group and > or = 2 g of walnuts per day for the control group. Participants provided at least six 24-hour dietary recalls and completed a self-administered FFQ. SUBJECTS: Eighty-seven adults aged 30-72 years (48 females, 39 males). RESULTS: Our findings from validation (by correlation with six diet recall measures) of the measurement of 32 nutrients by the FFQ are as follows. We found significant positive correlations (corrected for measurement error) between the FFQ and diet recalls for total energy (r = 0.34), total carbohydrate (r = 0.42), vegetable protein (r = 0.43), total fat (r = 0.51), polyunsaturated fat (r = 0.77), total fibre (r = 0.60), linoleic acid (r = 0.78) and alpha-linolenic acid (r = 0.79) - the last nutrient being an excellent nutrient biomarker of the intervention (walnut supplementation). Significant positive correlations were also found for vitamin C (r = 0.96) and certain minerals (r = 0.46-0.80 for calcium, phosphorus, magnesium, iron and potassium). Uncorrected correlations were also high (r>0.40) for retinol, beta-carotene, folate and alcohol. Both diet recalls and FFQ showed a similar significant difference in alpha-linolenic acid content between the walnut-supplemented and control diets. CONCLUSIONS: The FFQ demonstrated good relative validity in the estimation intake of some of the major nutrients in a dietary intervention trial and was a particularly valid estimate of an important nutrient biomarker of walnut supplementation.  相似文献   

Epizootic effect and aftermath in a pilot whale population     

Philippe Verborgh  Pauline Gauffier  Clmentine Brvart  Joan Gimnez  Ruth Esteban  Morgane Carbou  Elodie Debons  Renaud de Stephanis 《水产资源保护:海洋与淡水生态系统》2019,29(5):820-828

Consumption of feeds containing the antibiotic sulfadiazine by gilthead sea bream (Sparus aurata,L.) and rainbow trout (Onchorynchus mykiss,Walbaum)          下载免费PDF全文

Alicia Estévez  Mónica Ríus‐Francino  Jordi López  Joan Freixes 《Aquaculture Research》2017,48(5):2291-2302

A method for studying the efficacy of sulfadiazine as a marker to estimate feed intake is presented. Feeding studies were carried out with two species, rainbow trout as a freshwater fish model and gilthead sea bream as a marine fish model, using two temperatures and two sizes of juveniles. The study showed the different feeding behaviour observed in both species, depending on the temperature and the number of days feeding the particles with sulfadiazine, and confirmed a dominant‐subordinate behaviour especially in the case of gilthead sea bream juveniles.  相似文献   

Pasting Property Differences of Commercial and Isolated Rice Starch with Added Lipids and β‐Cyclodextrin     

Xiaoming Liang  Joan M. King  Fred F. Shih 《Cereal Chemistry》2002,79(6):812-818

Lipids are known to generally affect starch properties but the effects of lipid structure and β‐cyclodextrin (β‐CD) on different starches has not been investigated. This study compared the effects of lipids and β‐CD on pasting properties of isolated rice starch with commercial rice starch. Flour was defatted by Soxhlet extraction and deproteinated by alkaline protease digestion. Fatty acids, monopalmitin (MP), tripalmitin, lysophosphatidylcholine (LC), lysophophatidylethanolamine (LE), each added at 0.2 and 0.6% (starch db), and β‐CD added at 2 and 6% (starch db) were tested. Pasting temperature (PT) increased with added phospholipid, particularly in the commercial starch, while all lipids except tripalmitin increased final viscosity (FV) and total setback (TSB). Breakdown (BKD) was mainly affected and increased by up to 39 RVU for fatty acids while decreasing by up to 80 RVU for other lipids in both starches. TSB doubled by the addition of 0.6% MP but decreased to onethird by 0.6% LE or LC. Addition of β‐CD decreased minimum viscosity (MV) and FV while increasing BKD in isolate but decreased TSB in commercial starch.  相似文献   

Early weaning of southern flounder, Paralichthys lethostigma, larvae and ontogeny of selected digestive enzymes     

Cynthia K. Faulk  G. Joan Holt 《Aquaculture (Amsterdam, Netherlands)》2009,296(3-4):213-218

There is considerable interest in rearing Southern flounder, Paralichthys lethostigma, for commercial production and for stock enhancement. Both goals depend upon excellent larval nutrition for the production of robust juveniles. The current use of live prey for larviculture is an expensive and time consuming process that can be alleviated by weaning larvae onto dry feed. A study was conducted to assess the potential for early weaning of southern flounder larvae onto a microdiet (MD). In addition, the activity of selected digestive enzymes was measured during ontogeny to evaluate the digestive capabilities of the larvae over time. Pancreatic enzyme activities (U larva^− 1) were very low or undetectable at hatching and a marked increase in activity was not observed until the larvae reached 4 mm (~ 11 dph) in standard length for chymotrypsin (24–44,000) and 6 mm (~ 25 dph) for amylase (< 1–24), trypsin (1–18) and bile salt-dependent lipase (0–443). Acid protease activity (~ 1.0) was detected once the larvae were 8.5–9.0 mm (37–39 dph) in length although a sizeable increase in activity (> 10.0) was not observed until after complete metamorphosis (> 11.0 mm; 40–45 dph). Feeding regimes employed for the weaning study consisted of a live feed control (C) and a combination of live feed and MD in which the addition of the MD was initiated on 11 dph and live feed terminated on 17 (T17), 23 (T23) or 29 (T29) dph. At the end of the study (35 dph), mean standard length and the percent of settled fish were significantly greater for fish in the control treatment (8.3 mm; 21.1%) than for fish fed any combination of live prey and MD (6.4 mm; 2.0%). Average survival was 27.7% and no significant differences were noted among treatments. However, the number of fish exhibiting spinal deformities, lordosis, was significantly lower in the control and T29 treatments (1.7%) than the T17 and T23 treatments (25%). The results of this study indicate that southern flounder larvae readily wean onto dry feed prior to the onset of metamorphosis. However, decreased growth and a high incidence of lordosis emphasize the need for the development of a more appropriate MD for this species when digestive enzyme activities are relatively low and gastric digestion is absent.  相似文献   

Insecticidal activity and mode of action of 2,4‐diaminopyrimidines     

Joel M Wierenga  Thomas G Cullen  Jane A Dybas  Robert N Henrie II  Clinton J Peake  M Joan Plummer 《Pest management science》2000,56(3):233-236

Three 2,4‐diaminopyrimidines were tested against several insect species. They were active against lepidopteran pests with LC₅₀ values <3 mg liter⁻¹ for most species tested. They were also active against two‐spotted spider mite, Tetranychus urticae, (LC₅₀ 10–40 mg liter⁻¹). Folinate, but not hypoxanthine or thymidine was found to be an effective rescue agent, requiring a concentration of 100 mg liter⁻¹ diet to rescue half of the intoxicated larvae. The results confirm dihydrofolate reductase to be the site of action for these insecticides and are consistent with the mode of action of folinate rescue in mammals. © 2000 Society of Chemical Industry  相似文献