桂西北喀斯特坡地土壤137Cs的剖面分布特征及其指示意义

分析了¹³⁷Cs及土壤有机碳（SOC）在桂西北典型峰丛坡地及岩溶裂隙中的剖面分布特征,探讨了¹³⁷Cs方法在喀斯特坡地的适用性及其指示的坡面土壤侵蚀特征.结果表明：所有剖面¹³⁷Cs与SOC均显著相关,两者可能有相同的流失途径;次生林坡地¹³⁷Cs主体分布深度在24 cm以内,中上及中坡剖面随深度呈指数递减分布,地表无侵蚀或侵蚀轻微,坡脚剖面呈较严重侵蚀形态;坡耕地剖面¹³⁷Cs在耕层内均匀分布,中上坡及中坡主体分布深度在15 cm左右,面积活度远低于背景值,土壤侵蚀剧烈,坡脚分布深度至45 cm,呈堆积形态;次生林坡脚剖面、耕地中上坡剖面及所有裂隙剖面,¹³⁷Cs在主体分布深度以下有断续极微量的分布,指示了喀斯特坡地土壤颗粒有随降雨沿地表负地形向地下流失的趋势,但流失量轻微.     

Memorization of nuclear atmospheric tests by rhizomes and scales of the mediteranean seagrass Posidonia oceanica (Linnaeus) Delile

Determination of the age of rhizome sections of Posidonia oceanica (Linnaeus) Delile (Potamogetonaceae) by the examination of their dead leaf scales (lepidochronology), makes it possible to cut out the rhizomes in precisely dated 1- or 5-year sections. With increasing age of the section, the annual section length and the C:N ratio increase, while the dry weight per unit length and the ratio of dry weight:ash weight decrease. At a site where the only significant ¹³⁷Cs contamination can be ascribed to global nuclear fallout bombs, the activity of ¹³⁷Cs was measured i n 5-year age groups of rhizomes and scales separately. The maximum activity of ¹³⁷Cs in scales occurred in groups produced between 1960 and 1964, a period during which a peak of activity occurred in fallout. The distribution of ¹³⁷Cs activity in rhizome age groups indicates an apparent lag, perhaps owing to transport of material in the rhizome. In situ dead rhizome scales of P. oceanica thus constitute a memory, at least 30-years long, of an environmental chemical pulse. Posidonia oceanica could prove a valuable tool for marine-pollution surveys.     

2013年北太平洋公海渔场柔鱼体内典型放射性核素分析及风险评估

为了解福岛核泄漏放射性核素对北太平洋公海渔场的后续性污染影响情况,于2013年8—11月在北太平洋公海渔场(40°—44° N、145°—160° E)采集柔鱼样品,利用超低本底HPGe γ 谱仪分析5种放射性核素.结果表明: ¹³⁴Cs和^110mAg未检测出高于本底值的比活度,而²¹⁰Pb、¹³⁷Cs和⁴⁰K均有检出.其中²¹⁰Pb在柔鱼体的比活度范围为0.99～7.60 Bq·kg^-1,¹³⁷Cs的比活度范围为最低检测限～0.37 Bq·kg^-1,⁴⁰K的比活度范围为46.00～107.00 Bq·kg^-1.²¹⁰Pb核素含量在柔鱼250～300 mm胴长组分布最高;在200～250和>400 mm胴长组中最低.¹³⁷Cs含量在柔鱼200～250 mm胴长组中最高;在250～300和350～400 mm胴长组较低.⁴⁰K核素含量在柔鱼250～300 mm胴长组中最高,在150～200 mm胴长组最低,总体分布比较均匀.3种核素在柔鱼的不同组织中含量不同,但均在内脏中含量最高.通过风险评估发现,北太平洋公海渔场所有检测的海洋生物的放射性核素含量值与基准值的熵值均未超过1,说明目前核辐射对该海域渔业资源的影响暂无大风险.研究可为福岛核事故对海洋环境生态影响及公众健康危害评估提供理论依据.     

Chernobyl-derived radiocaesium in fish as dependent on water quality and lake morphometry

¹³⁷Cs concentrations in perch Perca fluviatilis , pike Esox lucius and roach Rutilus rutilus obtained from lakes of different size and water quality in an area which received about 10–67 kBq m⁻²¹³⁷Cs, were compared with environmental data. Radiocaesium concentrations were highest in pike, and were about two to three times higher in the pike and perch than in the roach. The largest perch had about four times more ¹³⁷Cs than the smallest ones, but the activities in the pike and roach were independent of fish size. All of the water quality parameters examined correlated with ¹³⁷Cs concentrations in the fish, but the concentrations of ¹³⁷Cs in the bottom sediment did not. ^l37Cs fallout and water retention time in lakes showed a positive correlation with fish ¹³⁷Cs, while the size of the catchment area, phosphorus content of the water, water colour, pH and electrical conductivity showed a negative one. Thus there was more ¹³⁷Cs in the fish from the oligotrophic lakes than from the eutrophic ones, from the less humic lakes than from the more humic ones, from the more acid than from the less acid ones and from the lakes containing less potassium than from those containing more potassium. The depth, area and volume of the lake did not affect radiocaesium in the fish. Regression equations are presented for predicting ¹³⁷Cs in fish on the basis of environmental data. Fallout, total phosphorus and pH together had the highest influence in multiple regression models but were less significant in the roach than in the perch and pike.     

Processing and transfer of epidermal growth factor in developing rat jejunum and ileum

Using everted sac technique we demonstrated the transfer of ¹²⁵I-mEGF across the jejunal and ileal walls of suckling, weanling and adult rats. The transfer by the suckling rat jejunum and ileum was significantly inhibited by the presence of dinitrophenol and sodium azide or by the replacement of sodium with potassium or choline. RP-HPLC analysis detected carboxy-terminal processing of ¹²⁵I-mEGF in suckling and adult rat jejunum and ileum. Suckling rat jejunum produced ¹²⁵I-des(53)mEGF and ¹²⁵I-des(49–53)mEGF, whereas ¹²⁵I-des(48–53)mEGF was detected in suckling rat ileum or adult rat jejunum and ileum. All three forms of ¹²⁵I-mEGF bound to anti-EGF antibody and EGF receptors. The receptor binding of ¹²⁵I-des(53)mEGF was higher than that of ¹²⁵I-mEGF, but those of ¹²⁵-des(49–53)mEGF and ¹²⁵I-des(48–53)mEGF were greatly diminished. Results indicate a carboxy-terminal processing of mouse EGF during uptake and transfer in the small intestine of developing and adult rats, and the resulting products showed altered receptor binding. An identical amino acid sequence of the C-terminal pentapeptide of EGF from mouse, human and possibly rat may suggest a biological significance of C-terminal processing of EGF in the small intestine.     

Electrospray mass spectrometry of trans-[Ru(NO)Cl(dpaH)2] (dpaH=2,2′-dipyridylamine) and ‘caged NO’, [RuCl3(NO)(H2O)2]: loss of HCl and NO from positive ions versus NO and Cl from negative ions

The positive ion electrospray mass spectrometry (ESI-MS) of trans-[Ru(NO)Cl)(dpaH)₂]Cl₂ (dpaH=2,2′-dipyridylamine), obtained from the carrier solvent of H₂O–CH₃OH (50:50), revealed 1+ ions of the formulas [Ru^II(NO⁺)Cl(dpaH)(dpa)]⁺ (m/z=508), [Ru^IIICl(dpaH)(dpa⁻)]⁺ (m/z=478), [Ru^II(NO⁺)(dpa)₂]⁺ (m/z=472), [Ru^III(dpa)₂]⁺ (m/z=442), originating from proton dissociation from the parent [Ru^II(NO⁺)Cl(dpaH)₂]²⁺ ion with subsequent loss of NO (17.4% of dissociative events) or loss of HCl (82.6% of dissociative events). Further loss of NO from the m/z=472 fragment yields the m/z=442 fragment. Thus, ionization of the NH moiety of dpaH is a significant factor in controlling the net ionic charge in the gas phase, and allowing preferential dissociation of HCl in the fragmentation processes. With NaCl added, an ion pair, {Na[Ru^II(NO)Cl(dpa)₂]}⁺ (m/z=530; 532), is detectable. All these positive mass peaks that contain Ru carry a signature ‘handprint’ of adjacent m/z peaks due to the isotopic distribution of ¹⁰⁴Ru, ¹⁰²Ru, ¹⁰¹Ru, ⁹⁹Ru, ⁹⁸Ru and ⁹⁶Ru mass centered around ¹⁰¹Ru for each fragment, and have been matched to the theoretical isotopic distribution for each set of peaks centered on the main isotope peak. When the starting complex is allowed to undergo aquation for two weeks in H₂O, loss of the axial Cl⁻ is shown by the approximately 77% attenuation of the [Ru^II(NO⁺)Cl(dpaH)(dpa)]⁺ ion, being replaced by the [Ru^II(NO⁺)(H₂O)(dpa)₂]⁺ (m/z=490) as the most abundant high-mass species. Loss of H₂O is observed to form [Ru^II(NO⁺)(dpa)₂]⁺ (m/z=472). No positive ion mass spectral peaks were observed for RuCl₃(NO)(H₂O)₂, ‘caged NO’. Negative ions were observed by proton dissociation forming [Ru^II(NO)Cl₃(H₂O)(OH)]⁻ in the ionization chamber, detecting the parent 1− ion at m/z=274, followed by the loss of NO as the main dissociative pathway that produces [Ru^IIICl₃(H₂O)(OH)]⁻ (m/z=244). This species undergoes reductive elimination of a chlorine atom, forming [Ru^IICl₂(H₂O)(OH)]⁻ (m/z=208). The ease of the NO dissociation is increased for the negative ions, which should be more able to stabilize a Ru^III product upon NO loss.     

Schistosoma mansoni and Schistosoma japonicum: Utilization of amino acids

, , and 1972. Schistosoma mansoni and Schistosoma japonicum: utilization of amino acids. International Journal for Parasitology 2: 425–430. The production of ¹⁴CO₂ from 12 labeled amino acids by S. mansoni and S. japonicum was studied. No ¹⁴CO₂ was detected from incubations with glycine, isoleucine, leucine, lysine or phenylalanine. Differences were found between sexes and/or species for the other amino acids studied. Species related differences included a greater rate of metabolism of glutamic and aspartic acid by S. mansoni than by S. japonicum. Proline and histidine were utilized by S. mansoni males and females, respectively. S. japonicum male worms did not utilize proline, while histidine was not utilized by the female of this species. Major sex related differences included greater ¹⁴CO₂ production from glutamic acid, aspartic acid and arginine by S. mansoni males than by females, and the utilization of histidine by male S. japonicum but not by females. Incubation in tyrosine resulted in the release of only small amounts of ¹⁴CO₂ by female worms of both species but no ¹⁴CO₂ production by male worms.     

Effects of group I cations on the gelation of iota carrageenan

N.m.r. and rheological measurements have been used to study the gelation of iota carrageenan. Gelation has been found to occur only at polymer concentrations above the critical entanglement concentration. The high temperature sol state above the gel-sol transition appears to be an entangled polymer network. Although Li⁺ and Na⁺ ions are less effective at gelling the polymer than K⁺, Rb⁺ and Cs⁺ all cationic forms studied gel at sufficiently high polymer concentration and ionic strength. ⁷Li⁺, ²³Na, ³⁹K, ⁸⁷Rb and ¹³³Cs n.m.r. studies have been made as a function of temperature. The lithium salt form (2.2% w/w concentration) formed a viscoelastic solution at room temperature. The other salt forms gelled on cooling. The spectra of Li, Na and Cs carrageenan showed little change on heating whereas K and Rb spectra showed marked changes in apparent intensity. The nature of the cation interaction with the juntion zones is discussed.     

Identification of a cDNA encoding a novel C18-Δ polyunsaturated fatty acid-specific elongating activity from the docosahexaenoic acid (DHA)-producing microalga, Isochrysis galbana

Isochrysis galbana, a marine prymnesiophyte microalga, is rich in long chain polyunsaturated fatty acids such as docosahexaenoic acid (C22:6n-3, Δ^{4,7,10,13,16,19}). We used a polymerase chain reaction-based strategy to isolate a cDNA, designated IgASE1, encoding a polyunsaturated fatty acid-elongating activity from I. galbana. The coding region of 263 amino acids predicts a protein of 30 kDa that shares only limited homology to animal and fungal proteins with elongating activity. Functional analysis of IgASE1, by expression in Saccharomyces cerevisiae, was used to determine its activity and substrate specificity. Transformed yeast cells specifically elongated the C18-Δ⁹ polyunsaturated fatty acids, linoleic acid (C18:2n-6, Δ^9,12) and -linolenic acid (C18:3n-3, Δ^9,12,15), to eicosadienoic acid (C20:2n-6, Δ^11,14) and eicosatrienoic acid (C20:3n-3, Δ^11,14,17), respectively. To our knowledge this is the first time such an elongating activity has been functionally characterised. The results also suggest that a major route for eicosapentaenoic acid (C20:5n-3, Δ^5,8,11,14,17) and docosahexaenoic acid syntheses in I. galbana may involve a Δ⁸ desaturation pathway.     

Absorption of gamma-emitting fission products and activation products by rice under flooded and unflooded conditions from two tropical soils

Summary The absorption of gamma-emitting fission products¹⁰⁶Ru,¹²⁵Sb,¹³⁷Cs and¹⁴⁴Ce and activation products⁵⁹Fe,⁵⁸Co.⁵⁴Mn and⁶⁵Zn by rice plants grown on two contrasting tropical soils, namely, a blak soil (pellustert) and a laterite (oxisol), and the effects of flooding were studied under controlled conditions. Results indicated greater uptake of¹⁰⁶Ru and¹²⁵Sb from the black soil than from the laterite. In contrast, the uptake of¹⁴⁴Ce and¹³⁷Cs was greater in the laterite than in the black soil. Flooding treatment enhanced the uptake of all these fission products by rice plants in the laterite soil whereas this effect was observed only for¹²⁵Sb and¹³⁷Cs in the black soil.The plant uptake of activation products from the two soil types showed maximum accumulation of⁶⁵Zn followed by⁵⁴Mn,⁵⁹Fe and⁵⁸Co in both soil types. Besides, uptake of these nuclides was greater from the laterite soil than from the black soil. Flooding treatment for rice while showing a reduction of⁵⁹Fe uptake, showed an increase in plant uptake of⁵⁸Co,⁵⁴Mn and⁶⁵Zn in both soil types.     

Ethanol extraction of free amino acids from soil

Summary A technique was developed for extracting and analyzing the free amino acid fraction of soil. Ethanol was used as an extracting agent. Ethanolextraction curves showed 20 per cent ethanol was the optimum percentage for extraction. Extraction-time curves indicated 18 to 20 hours of extraction with 20 per cent ethanol produced satisfactory results.The free amino acid fraction of soil was characterized and the limitations of the technique were determined. The naturally occurring amino acids extracted with 20 per cent ethanol were limited to acidic and neutral amino acids; basic amino acids were not extracted in sufficient quantities to permit detection. Based on the percent recovery of amino acids incorporated into soil and extracted with 20 per cent ethanol 90 to 95 per cent of the acidic, 80 to 85 per cent of the neutral and 1 to 5 per cent of the basic amino acids used were recovered with the technique.     

The accumulation of radioactive caesium from food by the plaice (Pleuronectes platessa) and the brown trout (Salmo trutta)

The patterns of accumulation of caesium-137 from food by the tissues and organs of a marine teleost, the plaice ( Pleuronectes platessa ) and a freshwater teleost, the brown trout ( Salmo trutta ) are described and compared. Estimates of the biological half-times and steady-state concentrations are derived and individual organ intakes calculated. Rate constants are similar to those obtained from the accumulation from water studies. Plaice gut and liver have an 11 % increase and trout gut a 6 % increase in their share of the [¹³⁷Cs] intake arising from accumulation from food, compared with that arising from the accumulation from water. These increases were balanced by decreases in the muscle share of the intake. The overall absorption of [¹³⁷Cs] from food was 42% for plaice and 67% for trout.     

Role of Asp297 of the AT2 receptor in high-affinity binding to different peptide ligands

To determine how ligand-receptor interaction is affected by the charges of the amino acids at position 2 of the ligands and position 297 of the AT2 receptor, we generated the Asp297Lys mutant of AT2 and a ligand SarAsp²Ile. Asp297Lys mutant lost affinity to Ang II and SarIle however retained partial affinity to ¹²⁵I-CGP42112A. The SarAsp²Ile had high affinity to Asp297Lys (IC₅₀3.5nM) and partial affinity to the AT2 (IC₅₀15nM). Therefore, not only the charge, but also the length of the side arms of the amino acids at position 2 of the ligand and position 297 of the receptor affect their interaction.     

Flux of certain radionuclides in the blood-clam Anadara granosa Linneaus under environmental conditions

The flux of fission product nuclides, caesium-137. cerium-144. and ruthenium-106, in the Bombay harbour ecosystem has been measured over a period of six years (1970–1976). during which the input of controlled low level radioactive waste was gradually reduced by more than 20 times. Of the various pelagic and benthic species studied, the arcid clam Anadara granosa Linn, showed a specific affinity for all three radionuclides; sequence of the degree of bio-accumulation was Ce ? Ru > Cs. Furthermore, the concentration of these nuclides in the tissues varied with the levels in the sedimentary material, which in turn was related to the inputs, maintaining some kind of equilibrium. On reaching maximum accumulation the levels of all three nuclides in the clam population decreased exponentially with time although the radioactivity was still available especially in the sediment. This decrease of radioactivity is defined as an ‘ecological loss rate’. The ecological half-time for cerium-144 and ruthenium-106 was about 3.6 times longer, and that of caesium-137 significantly shorter, than their respective physical half-lives. The ecological half-times of all three radionuclides were predominantly influenced by the environment rather than by the biological half-lives. This indicates that the biological half-lives of these nuclides were much shorter than their respective ecological half-lives. The biological half-time of caesium-137 was biphasic; the short-lived component had a half-time of about three days and the long-lived component had one of about 15 days.The bio-accumulation of an activation product nuclide cobalt-60 in A. granosa increased with the time of exposure and reached a level significantly higher than that of caesium-137, but was independent of the ambient concentrations and temperature. Thus the species was found to maintain the tissue concentration of fission product nuclides, cerium-144, ruthenium-106, and caesium-137 through adjusting physiological flux rates, in equilibrium with the changing levels of radionuclides in the environmental matrices, but not of the activation product nuclide cobalt-60.     

Atg22p, a vacuolar membrane protein involved in the amino acid compartmentalization of Schizosaccharomyces pombe

The fission yeast Schizosaccharomyces pombe has a homolog of the budding yeast Atg22p, which is involved in spore formation (Mukaiyama H. et al., Microbiology, 155, 3816-3826 (2009)). GFP-tagged Atg22p in the fission yeast was localized to the vacuolar membrane. Upon disruption of atg22, the amino acid levels of the cellular fraction as well as the vacuolar fraction decreased. The uptake of several amino acids, such as lysine, histidine, and arginine, was impaired in atg22Δ cells. S. pombe Atg22p plays an important role in the compartmentalization of amino acids.     

Validity of multiple-time regression analysis in measurement of tritiated and iodinated leptin crossing the blood-brain barrier: meaningful controls

Multiple-time regression analysis has been used to study the influx of radiolabeled peptides and polypeptides across the blood-brain barrier (BBB). This study used both tritiated and iodinated leptin to clarify several issues associated with these measurements. Recombinant murine leptin was radiolabeled with ³H by derivatization or with ¹²⁵I by the iodobead method and each studied separately in mice. Intact ³H-leptin had a higher apparent influx rate from blood to brain than did intact ¹²⁵I-leptin, correlating with its higher proportion of reversible association with the capillary lumen that would misleadingly appear to reflect entry. Yet the majority of ³H-leptin and ¹²⁵I-leptin reached brain parenchyma. There was no significant difference in the influx rate between cerebral cortex and the subcortical regions, thus ruling out a predominant contribution of simple diffusion through the circumventricular organs or choroid plexuses outside the BBB. The influx of radiolabeled leptin, especially ¹²⁵I-leptin, was decreased by excess unlabeled leptin, supporting the presence of a saturable transport system for leptin at the BBB. To identify the specificity of the transport system and determine whether it is shared by ³H-leptin and ¹²⁵I-leptin, these radioactively labeled leptins were heat-denatured. Denaturation had no effect on the fast influx of ³H-leptin, but abolished the entry of ¹²⁵I-leptin into brain; excess denatured leptin failed to inhibit the influx of either ³H-leptin or ¹²⁵I-leptin. This indicates that the conformation of ¹²⁵I-leptin is similar to that of native unlabeled leptin, so that iodination would be the better choice for investigating the interaction of leptin with the BBB. However, ³H-leptin can use the same transport system, as shown by inhibition of its influx by unlabeled leptin, whereas the derivatization procedure altered its biophysical properties such that its non-saturated influx was greatly enhanced. Finally, the rapid influx of radioactively labeled leptin contrasted greatly with that of the reference compounds ^99mTc-albumin and ³H-inulin which had no significant penetration of the BBB. Thus, with additional considerations such as stability and interactions with the vasculature, multiple-time regression analysis is sensitive and selective for study of the penetration of peptides across the BBB.     

Some evidence of the enzymatic conversion of bovine suppressor phosphoseryl-tRNA to selenocysteyl-tRNA

In order to clarify the mechanisms of selenocysteine incorporation into glutathione peroxidase, some evidence to show the in vitro conversion of phosphoseryl-tRNA to selenocysteyl-tRNA is reported. [³H]Phosphoseryl-tRNA was incubated in a reaction mixture composed of SeO₂, glutathione and NADPH in the presence of selenium-transferase partially purified. Analyses of amino acids on the product tRNA showed that a part (4%) of [³H]phosphoseryl-tRNA was changed to [³H]selenocysteyl-tRNA. The conversion from seryl-tRNA^su or major seryl-tRNA_IGA was not found. Selenium-transferase was essential for the conversion. [³H]Selenocysteine, liberated from the tRNA, was modified with iodoacetic acid. The product was confirmed to be carboxymethyl-selenocysteine by two-dimensional TLC. Selenocysteyl-tRNA^su should be used to synthesize glutathione peroxidase by co-translational mechanisms.     

Observation of fallout in Hiroshima caused by the reactor accident at Chernobyl

Fallout from the reactor accident at Chernobyl has been surveyed at Hiroshima. gamma-rays from samples of aerosol, rain water and tap water were measured using low-background gamma-ray spectrometers and concentrations of activities were followed. Almost all of the nuclides detected in Europe were observed in Hiroshima. In addition to dominant volatile fission products of 131I, 132Te-132I and 103Ru, long-lived fission products 137Cs, 106Ru-106Rh, 125Sb and activities produced through the (n, gamma) process in the reactor such as 134Cs, 136Cs and 110mAg were observed in relatively high concentrations.     

Differential uptakes of different forms of soil nitrogen among major tree species in subalpine coniferous forests of western Sichuan,China

Aims Although acquisition of soil organic nitrogen (N)(mainly amino acids) by plants is a widespread ecological phenomenon in many terrestrial ecosystems, the rate of organic N uptake and their contributions to plant nutrient supply are poorly understood. Our objective was to determine the relative contributions of inorganic N (NO₃^–-N and NH₄⁺-N) and organic N (amino acids) to plant N uptake in a high-frigid forest ecosystem.Methods The differences in the uptake rate of three different forms of N (NO₃^–-N, NH₄⁺-N and glycine) were quantified by exposing seedlings of two dominant tree species (Picea asperata and Betula albo-sinensis) in subalpine coniferous forests of western Sichuan, China, to trace quantities of K¹⁵NO₃,¹⁵NH₄Cl and (U-¹³C₂/¹⁵N) glycine.Important findings Both ¹³C and ¹⁵N were significantly enriched in fine roots 2 h after tracer application, indicating the occurrence of glycine uptake in P. asperata and B. albo-sinensis seedlings. The seedlings of two tree species had a significant preference for NO₃^–-N compared with glycine and NH₄⁺-N, and the uptake rate of NO₃^–-N was 5 to 10 times greater than that of glycine and NH₄⁺-N. The roots of seedlings in the two species took up glycine more rapidly than NH₄⁺-N, implying that soil organic N (i.e., amino acids) could be an important N source for the two species in subalpine coniferous forests. The results of this study are of great theoretical significance for understanding N utilization strategies and nutrient regulation processes in plants of the high-frigid forest ecosystems.     

Enhancing effect of albumin hydrolysate on ethanol production employing Saccharomyces sake

The enhancing effect of albumin hydrolysate on ethanol production was investigated in ethanol fermentations using Saccharomyces sake. In batchwise ethanol production, addition of supplemental albumin hydrolysate and phosphatidylcholine, or albumin hydrolysate alone, brought about a more than 60% increase in final ethanol concentration (148 or 144 g/L compared with 88 g/L with no supplementation [control] after 72 h). The effect of the supplements is believed to be due to an enhanced alcohol tolerance of cells grown in media containing the supplements. Cells grown in media containing albumin hydrolysate were enriched in phenyalanine, tyrosine, and methionine in their plasma membranes. All three amino acids were also present in considerable amounts in the albumin hydrolysate. This fact suggests that the three amino acids, which are present in albumin hydrolysate, are incorporated into the plasma membranes of cells. Under ethanol production conditions in which only one amino acid among the components of albumin hydrolysate was excluded, namely phenlalanine, tyrosine, or methionine, significant reductions in ethanol production resulted. (c) 1995 John Wiley & Sons, Inc.