Bioassembly of acyl lipids in microspore-derived embryos of Brassica campestris L.

The native lipid composition and the capacity of cell-free extracts to biosynthesize acyl lipids in vitro were determined for the first time using the recently reported microspore-derived (MD) embryo system from the Brassica campestris low erucic acid line BC-2 (Baillie et al. 1992). The total lipid fraction isolated from midcotyledonary stage MD embryos (21 days in culture) was composed primarily of triacylglycerol (76%) with an acyl composition quite similar to that of mature BC-2 seed. When incubated in the presence of glycerol-3-phosphate, ¹⁴C 181-CoA, and reducing equivalents, homogenates prepared from 21-day cultured MD embryos were able to biosynthesize glycerolipids via the Kennedy pathway. The maximum in vitro rate of triacylglycerol biosynthesis could more than account for the known rate of lipid accumulation in vivo. The homogenate catalyzed the desaturation of 181 to 182 and to a lesser extent, 183. The newly-synthesized polyunsaturated fatty acids initially accumulated in the polar lipid fraction (primarily phosphatidic acid and phosphatidylcholine) but began to appear in the triacylglycerol fraction after longer incubation periods. As expected for a low erucic acid cultivar, homogenates of MD embryos from the BC-2 line were incapable of biosynthesizing very long chain monounsaturated fatty acyl moieties (201 and 221) from 181-CoA in vitro. Nonetheless, embryo extracts were still capable of incorporating these fatty acyl moieties into triacylglycerols when supplied with ¹⁴C 201-CoA or ¹⁴C 221-CoA. Collectively, the data suggest that developing BC-2 MD embryos constitute an excellent experimental system for studying pathways for glycerolipid bioassembly and the manipulation of this process in B. campestris.Abbreviations CPT sn-1,2-diacylglycerol cholinephosphotransferase - DAG diacylglycerol - DGAT diacylglycerol acyltransferase - DGDG digalactosyldiacylglycerol - G-3-P glycerol-3-phosphate - G-3-PAT glycerol-3-phosphate acyltransferase - LPA lyso-phosphatidic acid - LPAT lyso-phosphatidic acid acyltransferase - LPC lyso-phosphatidylcholine - LPCAT acyl-CoA: lyso-phosphatidylcholine acyltransferase - LPE lyso-phosphatidylethanolamine - MGDG monogalactosyldiacylglycerol - PA phosphatidic acid - PA Phosphatase, phosphatidic acid phosphatase - PC phosphatidylcholine - PE phosphatidylethanolamine - PG phosphatidylglycerol - TAG triacylglycerol - 181-CoA oleoyl-Coenzyme A - 181 oleic acid, cis-9-octadecenoic acid - 182 linoleic acid, cis-9,12-octadecadienoic acid - 183 -linolenic acid, cis-9,12,15-octadecatrienoic acid - 201 cis-11-eicosenoic acid - 221 erucic acid, cis-13-docosenoic acid; all other fatty acids are designated by number of carbon atoms: number of double bonds National Research Council of Canada Publication No. 35896     

Bacterial regeneration of ammonium and phosphate as affected by the carbon:nitrogen:phosphorus ratio of organic substrates

The effect of carbonnitrogenphosphorus (CNP) ratio of organic substrates on the regeneration of ammonium and phosphate was investigated by growing natural assemblages of freshwater bacteria in mineral media supplemented with the simple organic C, N, and P sources (glucose, asparagine, and sodium glycerophosphate, respectively) to give 25 different substrate CNP ratios. Both ammonium and phosphate were regenerated when CN and NP atomic ratios of organic substrates were 101 and 161, respectively. Only ammonium was regenerated when CN and NP ratios were 101 and 10–201, respectively. On the other hand, neither ammonium nor phosphate was regenerated when CN and NP ratios were 151 and 51, respectively. In no case was phosphate alone regenerated. As bacteria were able to alter widely the CNP ratio of their biomass, the growth yield of bacteria appeared primarily dependent on the substrate carbon concentration, irrespective of a wide variation in the substrate CNP ratio.     

Mutants of Arabidopsis with alterations in seed lipid fatty acid composition

Summary A diverse collection of mutants of Arabidopsis with altered seed lipid compositions was isolated by determining the fatty acid composition of samples of seed from 3,000 mutagenized lines. A series of mutations was identified that caused deficiencies in the elongation of 181 to 201, desaturation of 181 to 182, and desaturation of 182 to 183. In each of these cases the wild type exhibited incomplete dominance over the mutant allele. These results, along with results from earlier studies, point to a major influence of gene dosage in determining the fatty acid composition of seed lipids. A mutation was also isolated that resulted in increased accumulation of 183. On the basis of the effects on fatty acid composition, the nature of the biochemical lesion in three of the mutants could be tentatively attributed to deficiencies in activities of specific enzymes. The other mutant classes had relatively less pronounced changes in fatty acid composition. These mutants may represent alterations in genes that regulate lipid metabolism or seed development. The availability of the mutants should provide new opportunities to investigate the mechanisms that control seed lipid fatty acid composition.Abbreviations FAMES (fatty acid methyl esters) - PC (phosphatidylcholine) - 181 (oleic acid) - 182 (linoleic acid) - 183 (linolenic acid) - 201 (eicosenoic acid) Supported in part by grants from the USDA (No. 89-37262-4388), USDA/NSF/DOE Plant Science Center Program, the U.S. Department of Energy (No. AC02-76ER01338), Karlshamns Research Foundation, and the WSU Research and Arts Committee     

Sex determination in Sarotherodon (tilapia)

Summary The simplest possible model of the sex determination process adding autosomal influence to a minimal number of sex chromosomes was developed to explain matings of Tilapia (Sarotherodon) species. Eighteen different genotypes, each having two autosomes (AA, Aa, or aa) and two sex chromosomes (WX, WY, WW, XY, XX or YY) involved in sex determination, are predicted by the theory. Their sex (10 males and 8 females) were determined using a series of directed graphs, showing the relative strength of the chromosome pairs, developed on the basis of Chen's sex ratio results (Chen 1969). This theoretical model predicts eight different sex ratios (01, 13, 35, 11, 97, 53, 31, 10 ); three of them are not predicted by the WXYZ theory. The greatest part of these sex ratios have been obtained experimentally in extensive series of crosses between related species of Tilapia and their hybrids, carried out by several authors. The theory succeeds in explaining all of Chen's results, including those ratios 53 and 01 seen in certain crosses but not predicted by the WXYZ theory. The importance of the autosomes is seen in comparisons of the genotype pairs (AaWY, aaWY), (AaXY, aaXY) and (AAWW, AaWW) in which the first genotype in each case is male while the second is female as proven by the sex ratio results. The members of the pair differ only in the substitution of one autosome for the other. To test the theory, experiments consisting of hormonal sex reversion and a series of crosses are proposed. Finally, theoretical and practical implications of the theory are discussed.     

Cellular fatty acid composition of six fastidious,gramnegative, xylem-limited bacteria from plants

Composition of cellular fatty acids was determined for strains of fastidious, Gramnegative, xylem-limited bacteria causing or associated with Pierce's disease of grapevine, phony disease of peach, plum leaf scorch, stunt of ragweed, elm leaf scorch, and periwinkle wilt. The most abundant fatty acids were straight-chain 150, 160, 170, and 180, unsaturated 161, 181, and unsaturated 17-and 19=carbon homologs. Minor fatty acids included straightchain 120, 140, 190, and 200; an unsaturated 15-carbon homolog; hydroxy-substituted 2-OH 120, 3-OH 120, and 3-OH 140; and branched chain iso-140 and iso-200. Cyclopropane acids were not detected. Physiological age had no effect on fatty acid composition. Class analysis of data indicated relative uniformity within the group. Saturated even-carbon chains comprised 31%–42%, unsaturated acids 41%–52%, saturated odd-carbon chains 10%–18%, hydroxysubstituted chains 2%–7%, and branched-chains 1%–4% of total fatty acids. The ratio of saturated-unsaturated acids ranged from 0.8 to 1.2.     

Das Fettsäurespektrum des Flußkrebses Orconectes limosus und seine Beeinflussung durch die Nahrung

Zusammenfassung Das Fettsäurespektrum von männlichen Flußkrebsen Orconectes limosus wurde gaschromatographisch analysiert. Die Fettsäuren zeigen eine spezifische Verteilung auf die Lipidklassen. Das Gesamtspektrum entspricht dem Schema eines Süßwassertieres im Winter mit den größten Fraktionen: C160, C181, C202 und C204 (zusammen rund 53% der Gesamtfettsäuren). In verschiedenen Fraktionen wurden ungeradzahlige und verzweigte Fettsäuren gefunden.Durch Verfüttern von Kartoffeln und Lebertran kann das Spektrum beeinflußt werden. Die Fettsäuren in der Mitteldarmdrüse, und in weniger starkem Ausmaß im Restkörper, haben sich nach viermonatiger Fütterung mit Lebertran qualitativ und quantitativ dessen Spektrum angepaßt. Nach siebenmonatiger Fütterung mit Kartoffeln zeigen Mitteldarmdrüse und Restkörper ein Spektrum, das dem eines unbehandelten Kontrollkrebses ähnelt und sowohl C182 als auch höher ungesättigte Fettsäuren enthält. Hierfür kommen zwei Deutungen in Frage: Entweder wird das Spektrum der Fettsäuren in Strukturlipiden aufrechterhalten, oder es erfolgt de novo Synthese einer C18:2^6,9-Fettsäure und deren Verlängerung analog dem von Wirbeltieren bekannten Weg.

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The fatty acid composition in the crayfish, orconectes limosus, and the effect of nutrition

Summary The fatty acid composition in the male crayfish, Orconectes limosus, was analysed by gas-liquid chromatography. The fatty acids were found to have a specific distribution in different lipid classes. The composition corresponds to those of a fresh water animal in winter with the most important acids: C160, C181, C202, C204 (including about 53% of the total acids). In several lipid classes oddnumbered and branched chain fatty acids could be detected.Potatoe and fish-liver oil diets influence the fatty acid composition. After four months feeding with fish-liver oil the fatty acids in the hepatopancreas and to a lesser extent in the rest body show a similar spectrum as the fed oil. After feeding for seven months with potatoes hepatopancreas and rest body exhibit a fatty acid composition representative for the untreated animal, which contains C182 as well as higher unsaturated acids. These findings support the hypotheses that either the fatty acid composition in the structure lipids was maintained or that a C182^6,9-fatty acid was de novo synthesized and elongated analogous to the known vertebrate pathway.

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Herrn Prof. Dr. K. Urich bin ich für die Anregung zu der vorliegenden Arbeit und für die Durchsicht des Manuskriptes zu großem Dank verpflichtet.     

Anaerobic biosynthesis of unsaturated fatty acids in the cyanobacterium,Oscillatoria limnetica

The mechanism for synthesis of monounsaturated fatty acids under aerobic and anaerobic conditions was studied in the facultative anaerobic cyanobacterium, Oscillatoria limnetica. The hexadecenoic acid (C161) of aerobically grown O. limnetica was shown to contain both the 7 (79%) and 9 (21%) isomers, while the octadecenoic (C181) acid was entirely the 9 acid. Incorporation of [2-¹⁴C] acetate into the fatty acids under aerobic conditions resulted in synthesis of the 7 and 9 C161 and the 9 C181. Synthesis of unsaturated fatty acids in the presence of DCMU required sulfide. Anaerobic incubations in the presence of DCMU and sulfide (less than 0.003% atmospheric oxygen) resulted in a two-fold increase in monounsaturated fatty acids of both 7 and 9 C161 and 9 and 11 C181. The synthesis of these isomers is characteristic of a bacterialtype, anaerobic pathway.Abbreviations DCMU 3(3,4-dichlorophenyl)-1,1-dimethylurea - MFA monounsaturated fatty acid     

Synthesis of aspartame precursor by solid thermolysin in organic solvent

Summary The enzymatic synthesis of a peptide compound was carried out successfully in homogeneous organic solvent.Solid Thermolysin was found to catalyze the synthetic reaction of N-benzyloxycarbonyl-L-aspartyl-L-phenylalanine methyl ester (Z-APM; a precursor of sweetner Aspartame) from N-benzyloxycarbonyl-L-aspartic acid (Z-L-Asp) and L-phenylalanine methyl ester (L-PheOMe) in a 98 percent organic medium (ethylacetatebenzenemethanolwater=5029192). The dissolution of enzyme was not observed. The optimal pH shifted to acidic side by 1.0 pH unit, compared with that in aqueous medium. The enzymatic activity of solid thermolysin with an average size of 3.4×9.5 m was determined to be 0.18 moles-product/(mg-solid)·h under the initial concentrations of L-PheOMe of 0.1M and Z-L-Asp of 0.05M, and at pH 6.0 and 40°C.     

Glycerolipid-fatty-acid desaturase deficiencies in chloroplasts from fruits of Capsicum annuum L.

Chloroplasts from fruits and leaves of Capsicum annuum cv. Bell Tower were purified on sucrose gradients, and the lipids were separated by column and thin-layer chromatography. The glycerolipids mono- and digalactosyldiacylglycerol (MGDG, DGDG), sulfoquinovosyldiacylglycerol (SQDG), and phosphatidylglycerol (PG) were quantified, and the fatty-acid composition at the 1 and 2 positions of the glycerol moiety (sn-1 and sn-2) was determined after hydrolysis with position-specific lipases. In fruit chloroplasts, ³-trans hexadecenoate (trans-3-161) was absent and replaced by palmitate (160) at sn-2 of PG, and ^7,10,13-hexadecatrienoate (163) at sn-2 of MGDG was greatly reduced and largely replaced by linoleate (182). The ratio of 182 to linolenate (183) was consistently greater in glycerolipids from fruit compared with leaf chloroplasts. The lower percentage of C-16 fatty acids at sn-2 indicated that prokaryotic molecular species were reduced by 15% in DGDG, 40% in SQDG, and 90% in MGDG, in fruit compared with leaf chloroplasts. The MGDGDGDG ratios in fruit and leaf chloroplasts were 1.21 and 2.21, respectively. Taken together, the data indicate that chloroplasts in Capsicum fruit are deficient in three desaturases: those that convert 1) 160 to ³-trans-161 at sn-2 of PG, 2) 160 to ⁷–cis-161 at sn-2 of MGDG, and 3) 182 to 183 at both sn-1 and sn-2 of various chloroplast glycerolipids.Abbreviations Chl chlorophyll - DGDG digalactosyldiacylglycerol - FS free sterol - GL galactolipid - MGDG monogalactosyldiacylglycerol - PE phosphatidyl ethanolamine - PG phosphatidylglycerol - PL phospholipid - SQDG sulfoquinovosyldiacylglycerol We are grateful to Dr. Roger Calza for providing us with the tobacco gt11 cDNA expression library and to Dr. Eric Huttner for his advice throughout the screening procedure. We also wish to thank M. Gosse for his assistance in growing and maintaining our plants. T.W.B. was supported by a BAP research grant from the Commission of the European Communities.     

Meiotic segregation of five different reciprocal translocations in the onion fly,Hylemya antiqua (Meigen)

For one translocation (T14) with short interstitial segments in Hylemya antiqua significant differences in segregation behaviour between males and females were observed. In males the ratio of alternate:adjacent 1:adjacent 2 was approximately 730 and in females about 813. This difference is attributed to the difference in type of chromosome association. Female meiosis is chiasmate and male meiosis is achiasmate. It is suggested that meiotic pairing in males results in relative short Coorientation Determing Distances (CDDs) between homologous centromeres which favours alternate and adjacent 1 segregation. In females because of non-localized chiasmata on the average no differences in CDD between homologous and nonhomologous centromeres are expected. This might explain the occurrence of coorientation between non-homologous centromeres resulting in adjacent 2 segregations. Four other translocations with longer interstitial segments than T14 showed in males as well as females predominantly an alternate and adjacent 1 segregation, adjacent 2 was hardly found (0–3.6%). The longer distance between non-homologous centromeres is probably the reason.     

Production of an extracellular polysaccharide byAgrobacterium sp DS3 NRRL B-14297 isolated from soil

A bacterium isolated from soil and identified asAgrobacterium sp produced a water-soluble extracellular polysaccharide capable of producing highly viscous solutions. Gas chromatographic analysis revealed a sugar composition of glucose, galactose and mannose in the molar ratio of 7.52.41, together with 3.7% (w/w) pyruvic acid. Methylation analyses showed the presence of (13)-, (14)- and (16)-linked glucose, (13)- and (14, 16)-linked galactose and a small portion of (13)-linked mannose residues. Succinic acid was not present. The molecular weight of the polysaccharide was estimated by light scattering to be 2×10⁶ Da. The viscosity of solutions containing the polysaccharide remained constant from pH 3 to 11, and decreased by 50% when heated from 5 to 55°C. Maximum yield of the polysaccharide, 20 g L^–1, was reached in 48 h at 30°C incubation.     

N-3 and n-6 fatty acid metabolism in undifferentiated and differentiated human intestine cell line (Caco-2)

Metabolism of n-6 and n-3 fatty acids in the undifferentiated and differentiated human adenocarcinoma colon cell line (Caco-2) was studied. In cells incubated with either 182n-6 or 183n-3, no significant amounts of long chain n-6 and n-3 metabolites were found. Incubation with either 183n-6 or 184n-3 raised significantly the levels of 203n-6 and 204n-3, respectively. In the undifferentiated cells, significant proportions of 203n-6 and 204n-3 were further 5-desaturated to form 204n-6 and 205n-3, respectively. Incubation with either 204n-6 or 205n-3 raised the levels of their direct elongation products, 224n-6 and 225n-3, respectively. Incubation with 224n-6 or 225n-3 increased the levels of 204n-6 and 205n-6. These results suggest that 6-desaturation in the Caco-2 cells is less active in comparision with elongation, 5-desaturation and retro-conversion. These enzymes were modulated by the state of differentiation, and appeared to be non-specific to n-3 and n-6 fatty acids. When cells were incubated with 183n-6 and 184n-3 concomitantly, the levels of incorporation of total n-6 fatty acids into cellular lipids were greater than those of the n-3 fatty acids, whereas the ratios of 20+22 carbon metabolites to 18-carbon precursor favored n-3 over n-6 fatty acids. These results suggest that n-3 and n-6 fatty acids were not metabolized identically in Caco-2 cells.     

Genetics of fertility restoration in hybrid rice

Summary The cross combination involving 14 male-sterile lines in rice, when crossed with different maintainers, showed fertility restoration in certain combinations. When F₂ segregating populations were classified based on spikelet fertility, fertility restoration was shown to be governed by 31, 9331, and 1231, due to allelic differences. This indicated that the cytosterility of the same group showed monogenic fertility restoration, whereas crossing plants belonging to different cystosterile groups showed a digenic pattern of segregation.     

Localization of the gene for human heart fatty acid binding protein to chromosome 1p32-1p33

Among 639 spontaneous abortions between the 8th and 14th week of gestation 342 (53.5%) revealed an abnormal karyotype. While the rate of trisomies distinctly increased with advancing maternal age, a decrease in the rate of 45,X conceptuses and polyploidies was observed among abortions from older women. The overall relation of XXXXXXYY among the tetraploidies was 1411 and that of XXXXXYXYY among the triploidies was 26 361. However, when the latter was related to maternal age, a reversal of the XXXXXY ratio of 12 in the younger to 21 in the older age groups became evident. Furthermore a decrease in the rate of paternally derived partial hydatidiform moles was found among the triploid abortion specimens from older women. From these observations we conclude that digyny plays a major role in the origin of triploidy in the increased maternal age groups, while diandry related to immaturity of oocytes and impairment of oocyte cortical function is more frequent in triploid abortions from younger women.     

Circadian effects of hydrocortisone on the blood of the newt,Notophthalmus viridescens

Summary Differential counts of the leucocytes of newts,Notophthalmus viridescens, were made at four times of day (200, 900, 1400 and 2100), 72 hours after the injection of hydrocortisone acetate (experimentais) or distilled water (controls). At all times, increases in neutrophils and decreases in lymphocytes were observed in experimentais as compared to the controls (Table 1). The increases in neutrophils in the experimental newts were most pronounced at 1400, and the decreases in the lymphocytes were greatest at 2100. The least degrees of neutrophilia and lymphopenia occurred at 900. Consequently, circadian variations in response to the hydrocortisone are indicated. The possible mechanism of mediation of the variations is discussed.Supported in part by National Science Foundation grant, GY-7661, to Sweet Briar College.     

Structure of the majorO-glycosidic oligosaccharide of monkey erythrocyte glycophorin

Sialic acids and the majorO-glycosidic oligosaccharide of glycophorin MK from monkey (Japanese monkey,Macaca fuscata) erythrocyte membranes were characterized.N-Glycolylneuraminic acid (neu5Gc) was found as the major sialic acid, which was confirmed by gas-liquid chromatography-mass spectrometry as the trimethylsilyl methyl ester. ThreeO-glycosidic oligosaccharide units were obtained from a tryptic glycopeptide that contained all of the carbohydrate units in glycophorin MK by mild alkaline borohydride/borotritide treatment. Carbohydrate analyses of the oligosaccharides revealed that they were composed of Neu5Gc, galactose andN-acetylgalactosaminitol in the molar ratios of 111 (trisaccharide), 211 (tetrasaccharide) and 111 (pentasaccharide). The content of oligosaccharide units was estimated to be 1125 for penta-, tetra- and trisaccharide, respectively, based on the yields, the molecular weight, and the number of oligosaccharide attachment sites in the amino-acid sequence. The tetrasaccharide was the major oligosaccharide and its structure was proposed to be Neu5Gc2-3Gal1-3[Neu5Gc2-6]GalNAcol.     

The effect of spectral light deprivation on the spectral sensitivity of the honey bee

Summary The spectral sensitivity of spontaneous phototactic behavior was tested in short wavelength deprived bees and in control bees kept outdoors. Tests were performed with a y-maze with one branch illuminated, the other dark. The relative sensitivities for the control group were: green to blue to UV = 10.272.14. Short wavelength deprived bees show a distinct decrease in their sensitivity to short wavelengths. The relation green to blue to UV here was 10.220.27. Forager bees from outdooors, short wavelength deprived for 10 days, showed a relation of green to blue to UV of 10.261.04. Electrophysiological investigation of the compound eye using electroretinogram recordings showed no difference between deprived and control animals.     

A DNA sequence of Drosophila melanogaster with a differential telomeric distribution

A DNA sequence (8–19T) of 2.3 kilobase pairs (kb) of Drosophila melanogaster was localized by in situ hybridization to the extreme ends of polytene chromosomes and to the chromocenter. The relative abundance of this sequence at the ends of polytene chromosomes X2L2R3L3R is 13.41.902.7. This differential distribution is probably due to different copy numbers at the individual telomeric regions. Restriction enzyme analysis of genomic DNA shows that 8–19T sequences are interspersed with other sequences. The clone 8–19T, which contains most of this interspersed repetitive sequence, is itself not internally repetitive but has a complex sequence composition. Some of these sequences are transcribed into poly(A)⁺RNA. We suggest that the ends of Drosophila chromosomes are of a complex arrangement with some sequences common to all ends.     

Distribution and composition of particulate organic matter in the Ross Sea (Antarctica)

The biochemical composition and spatial distribution of particulate organic matter (POM) were studied in the Ross Sea (Antarctica) in summer 1989 to assess the quantitative role of organic carbon fractions in the cycling of organic matter in the water column. Large differences in chemical composition were observed between surface and deep layers. The results indicated that, despite large geographical differences, POM was quite homogeneous, of phytoplankton origin and mostly detrital. Different ratios were used to investigate the changes in biochemical composition of particulate organic matter in relation to the ice-melting: CN (organic carbonorganic nitrogen ratio) and C-POMPOC (sum of carbohydrate, protein and lipid carbontotal organic carbon ratio) were used to analyse the percentage of refractory organic material. PPRTPCHO (proteincarbohydrate ratio) were used to establish POM age and RNADNA ratios as a relative measure of particulate activity; POCChl a and N-PPRTChl a ratios were used to estimate the autotrophic contribution to the suspended particulate organic matter. Despite its low caloric value (5.3 Kcal g POM^–1), an high caloric content in the photic layer (1.6 Kcal m^–3 of POM and 2.5 Kcal m^–3 of POC) was found thus indicating that a large amount of food was available to higher trophic levels.     

Nutrient proportions in foliage of semi-mature loblolly pine

Summary Nitrogen and phosphorus limitations to growth are common in many loblolly pine (Pinus taeda) stands. Interactions of these nutrients may complicate interpretation of foliar nutrient analysis for predicting response to forest fertilization. Proportions of foliar nutrient concentrations (and the changes in these proportions following fertilization) were examined in 36 semi-mature loblolly pine plantations in the southeastern United States. Mean proportions of nutrient concentrations (NPKCaMg) for non-fertilized stands were 1009.336.517.29.2. Potassium and phosphorus were higher. Nitrogen fertilization generally decreased the PN ratio and enhanced growth, indicating a nitrogen deficiency in most stands under study. Additions of nitrogen and phosphorus together yielded a significant increase in the PN ratio. Effects of fertilization effects on other nutrient concentration ratios were also examined.Paper No. 9401 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695.