An arabinogalactan from the fibres of cotton (Gossypium arboreum L.)

An acidic arabinogalactan has been isolated from fibres of the cotton plant (Gossypium arboreum L.) at the stage of intensive secondary-wall formation. The polysaccharide contains arabinose, galactose, rhamnose, and glucuronic acid residues in the molar ratios 1:1.2:0.1:0.2. Periodate oxidation and methylation studies showed that there is a main chain of (1→3)-linked galactopyranosyl residues to which side chains are attached at O-6. The side chains consist of (1→6)-linked galactopyranosyl residues substituted at O-3 by (1→5)-linked arabinofuranosyl chains. Terminal galactopyranosyl, rhamnopyranosyl, and glucopyranuronosyl groups are also present. Enzymic hydrolysis showed that the configurations of the galactose and arabinose residues are d and l, respectively.     

Structural features of two amyloids from the hemi-cellulosic fraction of field-bean (Dolichos lablab) hulls

Two amyloid-type fractions were isolated from field-bean (Dolichos lablab) hulls by 10% alkali extraction followed by acetylation and solvent fractionation. The major, chloroform-insoluble fraction and a minor, chloroform-soluble fraction were found to be homogeneous in sedimentation analysis and molecular-sieve chromatography. The polysaccharides contained xylose and glucose in various proportions. Methylation analysis, periodate oxidation, Smith degradation, oxidation by chromium trioxide, and oligosaccharide studies indicated a new type of structure for the major fraction (glucose:xylose ratio of 1.9:1) in that it had a backbone of (1→4)-linked β-d-glucose residues interspersed with single or multiple residues of (1→4)-linked β-d-xylose, and to which some single d-xylosyl groups are attached through O-6 of d-glucose. In contrast, the minor fraction (glucose:xylose ratio of 1:3.7) had a backbone of (1→4)-linked β-d-xylose interspersed with (1→4)-β-d-glucose and having a side chain of d-xylose, attached through O-6 of d-glucose. The third fraction was found to be a mixture of linear (1→4)-d-glucan and (1→4)-d-xylan.     

百合花粉母细胞间染色质穿壁运动前次生胞间连丝形成的研究

百合花粉母细胞间染色质穿壁运动前(细线期到偶线期)的花药,用一般电镜制片法和铅沉淀法对酸性磷酸酶活性的细胞化学反应产物的定位实验,其结果总结如下:(1)形成次生胞间连丝通道水解作用所需的酶可能是由“类溶酶体”小泡或由内质网腔直接分泌的;(2)次生胞间连丝通道的水解作用,可在细胞壁的两边细胞同时开始,先形成半胞间连丝,然后贯穿??在一起;或从一侧开始,一直穿孔到另一边,最后两者都能形成胞间连丝;(3)用铅沉淀法进行的酸性磷酸酶细胞化学的定位实验表明:在质膜、内质网、类溶酶体小泡中的酶活性反应产物沉积的部位与一般电镜法制备的切片上看到的电子致密度物质的分布情况完全一致,(4)用X-射线微区能谱分析的结果表明:沉淀物中含有铅元素,确实是磷酸铅。因此我们推测所谓“类溶酶体”以及内质网所分泌的水解酶,可能具有果胶酶、纤维素酶和半纤维素酶的性质,它们都能降解、穿孔各自的细胞壁形成胞间连丝。     

Sequential conversion of the glutathionyl side chain of slow reacting substance (SRS) to cysteinyl-glycine and cysteine in rat basophilic leukemia cells stimulated with A-23187

In rat basophilic leukemia (RBL-1) cells stimulated with A-23187, the major slow reacting substance (SRS) species contain glutathione, cysteinyl-glycine, or cysteine in their side chains, corresponding or closely related to leukotrienes LTC₄, LTD₄, and LTE₄, respectively.³ Evidence is presented that most of the SRS produced during the first few minutes of stimulation by the ionophore has a glutathionyl side chain which is sequentially converted to cysteinyl-glycine and cysteine.     

Regeneration of lipophilic antioxidants by NAD(P)H:quinone oxidoreductase 1

Summary.  The aim of this work was to study the activity of NAD(P)H:(quinone acceptor) oxidoreductase 1 (EC 1.6.99.2) in the regeneration of lipophilic antioxidants, alpha-tocopherol, and reduced-coenzyme Q analogs. First, we tested whether or not two isoforms of the NAD(P)H:(quinone acceptor) oxidoreductase 1 designated as “hydrophilic” and “hydrophobic” (H. J. Prochaska and P. Talalay, Journal of Biological Chemistry 261: 1372–1378, 1986) show differential enzyme activities towards hydrophilic or hydrophobic ubiquinone homologs. By chromatography on phenyl Sepharose, we purified the two isoforms from pig liver cytosol and measured their reduction of several ubiquinone homologs of different side chain length. We also studied by electron paramagnetic resonance the effect of NAD(P)H:(quinone acceptor) oxidoreductase 1 on steady-state levels of chromanoxyl radicals generated by linoleic acid and lipooxygenase and confirmed the enzyme's ability to protect alpha-tocopherol against oxidation induced with H₂O₂-Fe²⁺. Our results demonstrated that the different hydrophobicities of the isoforms do not reflect different reactivities towards ubiquinones of different side chain length. In addition, electron paramagnetic resonance studies showed that in systems containing the reductase plus NADH, levels of chromanoxyl radicals were dramatically reduced. Morever, in the presence of oxidants, alpha-tocopherol was preserved by NAD(P)H:(quinone acceptor) oxidoreductase 1, supporting our hypothesis that regeneration of alpha-tocopherol may be one of the physiologic functions of this enzyme. Received May 20, 2002; accepted September 20, 2002; published online May 21, 2003 RID="*" ID="*" Correspondence and reprints: Departamento de Biología Celular, Fisiología e Inmunología, Facultad de Ciencias, Edificio Severo Ochoa, Campus de Rabanales, Universidad de Córdoba, 14014 Córdoba, Spain.     

Analysis of growth during phototropic curvature of cress hypocotyls

Abstract. Growth rates throughout an organ curving phototropically under continuous, unilateral while light were monitored by lime-lapse photography of cress hypocotyls marked into 1 mm sections by two rows of ion-exchange beads. Curvature resulted from an integrated sequence of changes in growth rate on each side of the organ, but the actual patterns of change and, therefore rales of curvature, differed within even this one species, depending upon the immediate pretreatment of the seedlings. Transference of seedlings from darkness to unilateral irradiation gave immediate growth inhibition on both sides of the organ. Curvature resulted from differential recovery of growth rate, being seen first on the shaded side, most prominently in the apical regions; only 2h after initial exposure to light did growth recover on the lit (lower) side. On the other hand, transfer of seedlings from omnilateral to unilateral irradiation of the same intensity resulted in simultaneous growth inhibition on the irradiated side and stimulated growth on the shaded side: this growth stimulation of the shaded side was greater than occurred in totally darkened control plants.     

Cytochrome c interaction with membranes. II. Comparative study of the interaction of c cytochromes with the mitochondrial membrane

A comparative study of the interaction of various cytochromes c with phospholipid vesicles and with mitochondrial membranes was undertaken. Both mammalian and yeast types of cytochrome c bind preferentially in the oxidized form as evidenced by the midpoint redox potential (E_m 7.0) becoming more negative upon binding. Cytochrome c which is reincorporated into cytochrome c-depleted mitochondria is kinetically comparable with the native cytochrome c component; rate of cytochrome b oxidation is maximally restored at ratios of c₁:c:a of 1:1:1. Comparison between the electron paramagnetic spectrum of cytochrome c labeled at methionine 65 or cysteine 103 reveals that upon binding to the mitochondrial membrane, the former is immobilized and not the latter. This result suggests that cytochrome c binds to the membrane at the side at which methionine 65 is located.     

Differences in Englemann Spruce Forest Biogeochemistry East and West of the Continental Divide in Colorado, USA

We compared Englemann spruce biogeochemical processes in forest stands east and west of the Continental Divide in the Colorado Front Range. The divide forms a natural barrier for air pollutants such that nitrogen (N) emissions from the agricultural and urban areas of the South Platte River Basin are transported via upslope winds to high elevations on the east side but rarely cross over to the west side. Because there are far fewer emissions sources to the west, atmospheric N deposition is 1–2 kg N ha⁻¹ y⁻¹ on the west side, as compared with 3–5 kg N ha⁻¹ y⁻¹ on the east side. Species composition, elevation, aspect, parent material, site history, and climate were matched as closely as possible across six east and six west side old-growth forest stands. Higher N deposition sites had significantly lower organic horizon C:N and lignin:N ratios, lower foliar C:N ratios, as well as greater %N, higher N:Ca, N:Mg, and N:P ratios, and higher potential net mineralization rates. When C:N ratios dropped below 29, as they did in east-side organic horizon soils, mineralization rates increased linearly. Our results are comparable to those from studies of the northeastern United States and Europe that have found changes in forest biogeochemistry in response to N deposition inputs between 3 and 60 kg ha⁻¹ y⁻¹. Though they are low by comparison with more densely populated and agricultural regions, current levels of N deposition, have caused measurable changes in Englemann spruce forest biogeochemistry east of the Continental Divide in Colorado. Received 22 January 2001; accepted 11 June 2001.     

“Lucy” (A.L. 288‐1) had five sacral vertebrae

A “long‐backed” scenario of hominin vertebral evolution posits that early hominins possessed six lumbar vertebrae coupled with a high frequency of four sacral vertebrae (7:12‐13:6:4), a configuration acquired from a hominin‐panin last common ancestor (PLCA) having a vertebral formula of 7:13:6‐7:4. One founding line of evidence for this hypothesis is the recent assertion that the “Lucy” sacrum (A.L. 288‐1an, Australopithecus afarensis) consists of four sacral vertebrae and a partially‐fused first coccygeal vertebra (Co1), rather than five sacral vertebrae as in modern humans. This study reassesses the number of sacral vertebrae in Lucy by reexamining the distal end of A.L.288‐1an in the context of a comparative sample of modern human sacra and Co1 vertebrae, and the sacrum of A. sediba (MH2). Results demonstrate that, similar to S5 in modern humans and A. sediba, the last vertebra in A.L. 288‐1an exhibits inferiorly‐projecting (right side) cornua and a kidney‐shaped inferior body articular surface. This morphology is inconsistent with that of fused or isolated Co1 vertebrae in humans, which either lack cornua or possess only superiorly‐projecting cornua, and have more circularly‐shaped inferior body articular surfaces. The level at which the hiatus' apex is located is also more compatible with typical five‐element modern human sacra and A. sediba than if only four sacral vertebrae are present. Our observations suggest that A.L. 288‐1 possessed five sacral vertebrae as in modern humans; thus, sacral number in “Lucy” does not indicate a directional change in vertebral count that can provide information on the PLCA ancestral condition. Am J Phys Anthropol 156:295–303, 2015. © 2014 Wiley Periodicals, Inc.     

The effect that side dominance has on barbell power symmetry during the hang power clean

The aim of this study was to examine whether ground reaction force (GRF) side differences were transmitted and related to bar end power output asymmetries during hang power clean (HPC) performance and whether progressive loading would intensify this effect. Differences between the dominant (D) and nondominant (ND) side average GRFs (AGRFs) of both feet and average bar end power outputs were recorded simultaneously from 15 recreationally trained male volunteers at 30, 60, and 90% 1RM using 2 force platforms and 3 high-speed digital cameras, quantifying side dominance from perceived handedness (left- or right-side dominance [LRSD]), GRF side dominance (force side dominance [FSD]), and bar end power output side dominance (barbell side dominance [BSD]). With the exception of the LRSD condition, differences between the D and ND side AGRFs were significant (FSD: 1.8-4.3%; BSD: 5.1-6.4%, p < 0.05). Bar end power output side differences were significant for all conditions (LRSD: 1.5-5.4%; FSD: 0.5-3.4%; BSD: 3.9-5.6%, p < 0.05). Progressive loading did not significantly affect GRF side differences or the FSD average bar power side differences. However, during the LRSD and BSD conditions, the 60 and 90% side average bar power side differences were >the 30% equivalents. Average GRF side differences were not related to bar end power output side differences. Because of the consistent side difference of 4-6% investigators and strength and conditioning practitioners should exercise caution when interpreting changes in bar end power output.     

Maxillary canine-first premolar transposition in two Native American skeletal samples from New Mexico

Tooth transposition is a rare anomaly in which the position of two adjacent teeth in the dental arcade is reversed. Maxillary canine and first premolar transposition (Mx.C.P1 transposition) is most commonly observed. Data from Native Americans samples are lacking. The purpose of this study was: 1) to document the occurrence of Mx.C.P1 transposition, and 2) to generate information on the prevalence of this transposition type among world populations. Eleven cases (M = 5, F = 4, ? = 2) of Mx.C.P1 transposition were identified in skeletal samples from Pecos Pueblo (n = 500) and Sambrito Village (n = 10), both in northern New Mexico. Nine cases were unilateral, 6 affecting the right side and 3 affecting the left side. The remaining 2 cases were bilateral. The prevalence rate of Mx.C.P1 transposition in African and Native American samples, including Pecos Pueblo (1.8%), is higher than in samples from Scotland, Sweden, Saudi Arabia, and India. Mx.C.P1 transposition frequencies vary between geographically distinct populations, although sample composition may be a factor contributing to sample variation. Am J Phys Anthropol 116:45–50, 2001. © 2001 Wiley‐Liss, Inc.     

The centrifugal horizontal cells in the lobula plate of the blowfly, Phaenicia sericata

Intracellular recordings combined with iontophoretic injection of Procion Yellow M4RAN were used to study the anatomy and physiology of the centrifugal horizontal cells (CH-cells) in the lobula plate of the blowfly, Phaenicia sericata.Anatomy: The CH-cells comprise a set of two homolateral, giant visual interneurones (DCH, VCH) at the rostral surface of each lobula plate. Their extensive arborizations in the lobula plate possess bulbous swellings (boutons terminaux). The arborization of one cell (DCH) covers the dorsal, and the arborization of the other cell (VCH) the ventral half of the lobula plate. Their axons run jointly with those of the horizontal cells through the chiasma internum and the optic peduncle. Their protocerebral arborization possesses spines; they form a dense network together with the axonal arborization of the horizontal cells, a second type of giant homolateral cell most sensitive to horizontal motion. The protocerebral arborization of the CH-cells gives rise to a cell body fibre which traverses the protocerebrum dorsally to the oesophageal canal. The cell body lies on the contralateral side laterally and slightly dorsally to the oesophageal canal in the frontal cell body layer.Physiology: The CH-cells respond with graded potentials to rotatory movements of their surround. Cells in the right lobula plate respond with excitation (excitatory postsynaptic potentials, membrane depolarization) to clockwise motion (contralateral regressive, ipsilateral progressive), and with inhibition (inhibitory postsynaptic potentials, membrane hyperpolarization) to counterclockwise motion in either or both receptive fields; CH-cells respond to motion presented to the ipsilateral and/or contralateral eye. Cells of the left lobula plate respond correspondingly to the reverse directions of motion. Vertical pattern motion and stationary patterns are ineffective.The heterolateral H1-neurone elicits excitatory postsynaptic potentials in the DCH-cell; these postsynaptic potentials are tightly correlated 1:1 to the preceding H1-action potentíal. The delay between the peak of the action potential and the beginning of the DCH-postsynaptic potential is 1.15 msec, agreeing very well with the value reported previously for the blowfly, Calliphora (Hausen, 1976a). The synaptic input and output connections of the CH-cells are discussed.     

Meta-Analysis: Lactobacillus Containing Quadruple Therapy Versus Standard Triple First-Line Therapy for Helicobacter pylori Eradication

Background:  Recent evidence showed that Lactobacilli could exert an inhibitory effect on Helicobacter pylori both in vitro and in vivo models. To systematically evaluate whether adding Lactobacilli to H. pylori eradication regimens could improve eradication rates and reduce side effects during anti- H. pylori treatment.
Materials and Methods:  Eligible articles were identified by searches of electronic databases. We included all randomized trials comparing Lactobacilli supplementation to placebo or no treatment during anti- H. pylori regimens. Statistical analysis was performed with Review Manager 5.0.10. Subanalysis analysis was also performed.
Results:  We identified eight randomized trials (n = 1372). Pooled H. pylori eradication rates were 82.26% (95% CI = 78.01–86.51%) and 76.97% (95% CI = 73.11–80.83%) for patients with or without Lactobacilli by intention-to-treat analysis, respectively, the odds ratio (OR) was 1.78 (95% CI = 1.21–2.62). The occurrence of total side effects had no significant difference and were 30.84% (95% CI = 24.82–36.86%) and 42.24% (95% CI = 35.89%–48.59%) for two groups, the summary OR was 0.49 (95% CI = 0.24–1.02); However, Lactobacilli supplementation group had lower occurrence of diarrhoea, bloating and taste disturbance.
Conclusions:  Our review suggests that supplementation with Lactobacilli could be effective in increasing eradication rates of anti- H. pylori therapy for first-treated patients. Furthermore, Lactobacilli showed a positive impact on some H. pylori therapy-related side effects.     

Immunity to carcinogen-induced transplantable fibrosarcoma in B2B2 chickens: V. Relationship to tumor cell-specific delayed hypersensitivity and serum antibody

Lasting immunity to the chemically induced (DMBA) fibrosarcomas (CHCT-NYU1, 2, and 4) of SC chickens ($\text{B2}\text{B2}$) can be obtained by injection of Corynebacterium parvum (CP)-primed chickens with tumor cells and CP in one wing and tumor cells alone in the other wing. The local delayed hypersensitivity (DH) reaction to CP in the wing inhibits local growth completely, whereas the tumor on the contralateral side shows transient growth. In the present studies, the development of tumor immunity was studied in detail by monitoring DH and antibody formation to the tumor cells and adoptive immunity with spleen cells in Winn tests. Injection of NYU1 cells alone in normal or CP-treated animals induced transient immunity in Winn tests in 50% of the animals, weak DH reactivity, and antibody detectable by immunofluorescence within the first 2 weeks. Chickens receiving both NYU1 cells and CP in one wing and NYU1 cells alone on the other side developed stronger DH reactions to the tumor cells and a higher incidence of immunity in Winn tests which was sustained throughout the period of observation. Antibody levels were similar to those of animals receiving tumor cells alone. In contrast, injection of CP and tumor cells on one side without a tumor challenge on the contralateral side did not induce detectable immunity in CP-primed chickens. Chickens immunized to NYU2 and 4 cells were also tested for DH reactivity and antibody formation. Studies on the cross-reactivity between the tumor lines showed that there was cross-reactivity at the humoral level while at the cellular level this was not apparent. However, animals immune to one tumor line rejected transplants of another tumor line. Observations on the antibody specificity(s) suggested that it was not directed against minor histocompatibility or avian sarcoma viral antigens. SC embryo fibroblasts could induce DH, and serum antibody induced by tumor cells usually reacted also with such embryo cells.     

Les polysaccharides des graines de quelques liliacees et iridacees

The alkali-soluble polysaccharides have been surveyed in the seeds of 7 species of the Liliaceae and 2 species of the Iridaceae. All appear to contain galactoglucomannans and/or glucomannans. The structure of the water-soluble galactoglucomannan from the endosperm of Asparagus officinalis has been studied in detail. It contains residues of glucose, mannose and galactose in the ratio 43:49:7. Hydrolysis of the fully methylated polysaccharide released 2,3,4,6-tetra-O-methyl-d-hexoses (mannose and glucose), 2,3,4,6-tetra-O-methyl-d-galactose, 2,3,6-tri-O-methyl-d-mannose, 2,3,6-tri-O-methyl-d-glucose, 2,3-di-O-methyl-d-mannose and 2,3-di-O-methyl-d-glucose in the molar proportions of 1:4.5:50:41:2:1·5. The following oligosaccharides were identified on partial hydrolysis of the galactoglucomannan: mannobiose, mannotriose, mannotetraose, cellobiose, glucopyranosylmannose, mannopyranosylglucose and a trisaccharide composed of two mannosyl residues and one glucosyl residue. The galactoglucomannan consists of a linear chain of β(1 → 4)-Iinked d-mannosyl and d-glucosyl residues, to which are attached single-unit galactosyl side chains. The galactose residues are linked 1 → 6, probably α. The terminal, non-reducing residues of the main chain may be either glucosyl or mannosyl units but the former predominate.     

Effect of antithrombin III, alpha 1-proteinase inhibitor and heparin on amidolytic activity of nerve growth factor (7S-NGF)

A series of potent inhibitors of angiotensin-converting enzyme (dipeptidyl carboxypeptidase, E.C. 3.4.15.1) derived from benzofused 1-carboxyalkyl-3-(1-carboxy-3-phenyl-propylamino) lactams (III) is described. In the most effective inhibitors (I50 2-4 X 10(-9)M) the lactam is 7 or 8 membered and the N-1 side chain is carboxymethyl or carboxyethyl. Conformational and steric factors pertinent to binding to the enzyme are discussed.     

Purification and chemical characterization of polysaccharides obtained from Lampteromyces japonicus by concanavalin A-sepharose affinity chromatography

Two classes of neutral polysaccharide which could not be separated from each other by conventional methods were isolated from the fungus, Lampteromyces japonicus, by affinity chromatography using concanavalin A-Sepharose. The polysaccharide retained on the concanavalin A-Sepharose column was eluted with 0.05 M methyl α-d-mannopyranoside and appeared to be α-mannan, while that which passed through the column was virtually all β-glucan.Both polysaccharides were subjected to Smith-type degradation, methylation, acetolysis and glucosidase treatment. The results indicated that the α-mannan contained predominantly α-(1 → 2)-linked side chains branching from an α-(1 → 6)-linked backbone at the (1 → 2,6)-linked mannopyranosyl residues. Galactose was attached to approximately one-quarter of the non-reducing mannose terminals. The β-glucan seemed to contain mainly (1 → 6)-linked side chains branching from a (1 → 3)-linked backbone at the (1 → 3,6)-linked glucopyranosyl residues.     

Minor and trace sterols in marine invertebrates : VI. Occurrence and possible origins of sterols possessing unusually short hydrocarbon side chains

Sterols with biosynthetically unusually short side chains (fewer than eight carbon atoms expected for primary squalene cyclization products) have been identified in the extracts of numerous marine invertebrates. The structures of the short side chain and conventional side chain sterols have been determined for various species of Porifera and Coelenterata. Sterol structures were determined by comparison of their mass spectra and gas chromatographic retention times with those of authentic or synthetic samples. Evidence is presented supporting the natural occurrence of these compounds in the tissues of the marine invertebrates as opposed to formation by degradative processes during sample handling or laboratory work-up. The short side chain sterols were found to possess predominantly the androst-5-en-3β-ol nucleus with C-17 alkyl side chains ranging from zero to six carbon atoms. Concentrations of short side chain sterols range from trace levels to over 5% of the sterol mixture in various species. The possible origins of these short side chain sterols are evaluated in the light of current knowledge of sterol function, biosynthesis, dealkylation, microbial degradation, and autoxidation. Known sterol autoxidations are reviewed, and possible singlet oxygen and free radical mechanisms of sterol side chain autoxidation (at physiological temperatures) which may lead to sterols with shortened hydrocarbon side chain are suggested. The possible autoxidative generation of short side chain sterols from known marine sterols by the suggested mechanisms is evaluated through application of the REACT computer program. Predicted short side chains are tabulated for each parent marine sterol side chain and then compared with the compositions of the actual sterols found in the marine extracts examined. The possible natural environmental or in vivo autoxidative formation of the short side chain marine sterols is supported by these evaluations.     

Ecosystem Responses to Nitrogen Deposition in the Colorado Front Range

We asked whether 3–5 kg N y⁻¹ atmospheric N deposition was sufficient to have influenced natural, otherwise undisturbed, terrestrial and aquatic ecosystems of the Colorado Front Range by comparing ecosystem processes and properties east and west of the Continental Divide. The eastern side receives elevated N deposition from urban, agricultural, and industrial sources, compared with 1–2 kg N y⁻¹ on the western side. Foliage of east side old-growth Englemann spruce forests have significantly lower C:N and lignin:N ratios and greater N:Mg and N:P ratios. Soil % N is higher, and C:N ratios lower in the east side stands, and potential net N mineralization rates are greater. Lake NO₃ concentrations are significantly higher in eastern lakes than western lakes. Two east side lakes studied paleolimnologically revealed rapid changes in diatom community composition and increased biovolumes and cell concentrations. The diatom flora is now representative of increased disturbance or eutrophication. Sediment nitrogen isotopic ratios have become progressively lighter over the past 50 years, coincident with the change in algal flora, possibly from an influx of isotopically light N volatilized from agricultural fields and feedlots. Seventy-five percent of the increased east side soil N pool can be accounted for by increased N deposition commensurate with human settlement. Nitrogen emissions from fixed, mobile, and agricultural sources have increased dramatically since approximately 1950 to the east of the Colorado Front Range, as they have in many parts of the world. Our findings indicate even slight increases in atmospheric deposition lead to measurable changes in ecosystem properties. Received 16 November 1999; accepted 8 February 2000.