THE PRODUCTION OF FOLIC ACID BY RAT LIVER IN VITRO     

Wright LD  Welch AD 《Science (New York, N.Y.)》1943,98(2538):179-182

The occurrence in urine and in acid-autoclaved grass and liver extracts of a substance which appears to participate in the synthesis of folic acid by rat liver in vitro is described. A similar effect is produced by synthetic xanthopterin. The effect of these materials might be accomplished by (1) catalysis of the enzymatic synthesis of folic acid; (2) the release of folic acid not liberated by takadiastase from tissue complexes; or (3) their serving as substrate material for the enzymatic synthesis of folic acid. The data presented favor the last hypothesis and suggest that xanthopterin, or a substance derived from it, may constitute a portion of the folic acid molecule. The probable involvement of compounds related to ranthopterin in the formation of hemocytopoietic substances in several animal species is discussed.  相似文献   

SOCIETIES RELATED TO THE SECTION ON ZOOLOGICAL SCIENCES (F) AND THE SECTION ON BOTANICAL SCIENCES (G)     

Cleland RE  Hamilton WJ  Lindstrom EW  Ackert JE  Welch PS  Houdek PK  Hunter GW 《Science (New York, N.Y.)》1941,93(2406):131-133

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THE RELATION OF YALE TO MEDICINE     

Welch WH 《Science (New York, N.Y.)》1901,14(361):825-840

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SOCIETIES RELATED TO BOTH THE SECTION ON ZOOLOGICAL SCIENCES (F) AND THE SECTION ON BOTANICAL SCIENCES (G)     

Hamilton WJ  Kaufmann BP  Ackert JE  Welch PS 《Science (New York, N.Y.)》1942,95(2458):144-145

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York river destratification: an estuary-subestuary interaction     

Hayward D  Welch CS  Haas LW 《Science (New York, N.Y.)》1982,216(4553):1413-1414

Destratification in the York River during high spring tides is the result of the interruption of normal two-layer estuarine flow by the advection of relatively fresh water into the river mouth from the Chesapeake Bay. This advection is due to the presence of a longitudinal salinity gradient in the bay and a difference in the tidal current phase between the river and the bay. Similar behavior is seen in other subestuaries of the Chesapeake Bay and may be common in subestuary-estuary interactions.  相似文献   

Meat and ascorbic acid can promote Fe availability from Fe-phytate but not from Fe-tannic acid complexes     

Engle-Stone R  Yeung A  Welch R  Glahn R 《Journal of agricultural and food chemistry》2005,53(26):10276-10284

This study utilized an in vitro digestion/Caco-2 cell model to determine the levels of ascorbic acid (AA) and "meat factor" needed to promote Fe absorption from Fe complexed with phytic acid (PA) or tannic acid (TA). AA reversed the inhibition of Fe absorption by PA beginning at a molar ratio of 1:20:1 (Fe:PA:AA) but essentially had no effect on the Fe complexed with TA. Fish also reversed the inhibition of Fe uptake by PA but not by TA. TA and fish decreased total Fe solubility. Iron in the presence of PA was highly soluble. AA, but not fish, increased the percentage of soluble Fe as Fe2+ in the presence of both inhibitors. The results indicate that monoferric phytate is a form of Fe that can be available for absorption in the presence of uptake promoters. In contrast, a TA-Fe complex is much less soluble and unavailable in the presence of promoters.  相似文献   

Effects of vermicomposts on growth and marketable fruits of field-grown tomatoes, peppers and strawberries: The 7th international symposium on earthworm ecology · Cardiff · Wales · 2002     

Norman Q. Arancon  Clive A. Edwards  Peter Bierman  James D. Metzger  Stephen Lee  Christie Welch 《Pedobiologia》2003,47(5-6):731-735

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Wood ant wars. The relationship between aggression and predation in the red wood ant (Formica polyctemaFörst): By A.A. Mabelis. Netherlands Journal of Zoology, 29(4): 451–620 (1979), 23 × 14·5 cm     

R. Colin Welch 《Biological conservation》1981,21(1):76-77

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Latitudinal differences in the duration of development of Neocalanus plumchrus copepodites     

Sonia D. Batten  David W. Welch  Tanya Jonas 《Fisheries Oceanography》2003,12(3):201-208

Quasi‐synoptic sampling along a transect from Alaska to California carried out in spring and summer 2000 using Continuous Plankton Recorders reveals that the abundant calanoid copepod Neocalanus plumchrus (Marukawa) reaches the surface at approximately the same time across the region. However, monthly sampling also reveals that the timing of peak biomass (when 50% of the population consists of copepodites at stage CV) occurs about 5 weeks earlier at the southernmost part of its range than at the northernmost part, with intermediate areas having intermediate timings. Surface water temperature differed by about 4°C between the warmer south and the cooler north, and we suggest that such a difference would reduce development duration by about 3 weeks. If food supply in the north is more conducive to lipid accumulation, as seems possible from phytoplankton biomass data, then the use of the differences in timing of peak N. plumchrus biomass in each area as a measure of the differences in development time may not be accurate. We find that the estimate of the time of peak biomass varying by about 5 weeks between north and south may be an exaggeration of the actual difference in the development duration. Temperature is probably the most important factor governing the shorter development duration of N. plumchrus in southern latitudes.  相似文献   

Temporal chemical variability in acid sensitive high elevation lakes     

E. B. Welch  D. E. Spyridakis  T. Smayda 《Water, air, and soil pollution》1986,31(1-2):35-44

Chemical indicators suggest that slight, but discernable acidification occurs during smowmelt in some highly sensitive Cascade Mountain Lakes (mean alkalinity 20 ueq L^?1). Although some SO₄ in the lakes (mean 13 μeq L^?1 ) comes from local geologic sources, several considerations suggest that some also comes from atmospheric deposition and anthropogenic sources. If sampling is stratified, the relatively low lake-to-lake and year-to-year variability in chemical constituents demonstrates that these highly sensitive lakes represent excellent indicators of acidification. The contention that precipitation pH >4.6 is needed for protection of sensitive lakes is supported. However, the slight but temporary acidification effect currently detectable during snowmelt, suggests that for adequate protection of these highly sensitive lakes, precipitation pH should be >4.7 to 4.8.  相似文献