bluuebunny/crossref_metadata_2025 huggingface dataset:
Self-Compatibility of Two Apricot Selections Is Associated with Two Pollen-Part Mutations of Different Nature
Authors: Vilanova Santiago , Badenes María Luisa , Burgos Lorenzo , Martínez-Calvo José , Llácer Gerardo , Romero Carlos
Published: August 2006

Loss of pollen-S function in Prunus self-compatible mutants has recently been associated with deletions or insertions in S-haplotype-specific F-box (SFB) genes. We have studied two self-compatible cultivars of apricot (Prunus armeniaca), Currot (S  C  S  C) and Canino (S  2  S  C), sharing the naturally occurring self-compatible (S  C)-haplotype. Sequence analysis showed that whereas the S  C-RNase is unaltered, a 358-bp insertion is found in the SFB  C gene, resulting in the expression of a truncated protein. The alteration of this gene is associated with self-incompatibility (SI) breakdown, supporting previous evidence that points to SFB being the pollen-S gene of the Prunus SI S-locus. On the other hand, PCR analysis of progenies derived from Canino showed that pollen grains carrying the S  2-haplotype were also able to overcome the incompatibility barrier. However, alterations in the SFB  2 gene or evidence of pollen-S duplications were not detected. A new class of F-box genes encoding a previously uncharacterized protein with high sequence similarity (approximately 62%) to Prunus SFB proteins was identified in this work, but the available data rules them out of producing S-heteroallelic pollen and thus the cause of the pollen-part mutation. These results suggest that cv Canino has an additional mutation, not linked to the S-locus, which causes a loss of pollen-S activity when present in pollen. As a whole, these findings support the proposal that the S-locus products besides other S-locus independent factors are required for gametophytic SI in Prunus.
Detection and Quantification of Unbound Phytochelatin 2 in Plant Extracts ofBrassica napusGrown with Different Levels of Mercury
Authors: Iglesia-Turiño Santiago , Febrero Anna , Jauregui Olga , Caldelas Cristina , Araus Jose Luis , Bort Jordi
Published: August 2006

The mercury (Hg) accumulation mechanism was studied in rape (Brassica napus) plants grown under a Hg concentration gradient (0 μ  m–1,000 μ  m). Hg mainly accumulated in roots. Therefore, the presence of phytochelatins (PCs) was studied in the roots of the plants. The high stability of the PC-Hg multicomplexes (mPC-nHg) seems to be the main reason for the lack of previous Hg-PC characterization studies. We propose a modification of the method to detect and quantify unbound PC of Hg in plant extracts via high-performance liquid chromatography coupled to electrospray tandem mass spectrometry and inductively coupled plasma mass spectrometry in parallel. We separated the PC from the Hg by adding the chelating agent sodium 2,3-dimercaptopropanesulfonate monohydrate. We only detected the presence of PC after the addition of the chelating agent. Some multicomplexes mPC-nHg could be formed but, due to their large sizes, could not be detected. In this study, only PC2 was observed in plant samples. Hg accumulation was correlated with PC2 concentration (r  2 = 0.98).
SUMO-Conjugating and SUMO-Deconjugating Enzymes from Arabidopsis
Authors: Colby Thomas , Matthäi Anett , Boeckelmann Astrid , Stuible Hans-Peter
Published: August 2006

Posttranslational protein modification by the small ubiquitin-like modifier (SUMO) is a highly dynamic and reversible process. To analyze the substrate specificity of SUMO-conjugating and -deconjugating enzymes from Arabidopsis (Arabidopsis thaliana), we reconstituted its SUMOylation cascade in vitro and tested the capacity of this system to conjugate the Arabidopsis SUMO isoforms AtSUMO1, 2, and 3 to the model substrate ScPCNA from yeast (Saccharomyces cerevisiae). This protein contains two in vivo SUMOylated lysine residues, namely K127 and K164. Under in vitro conditions, the Arabidopsis SUMOylation system specifically conjugates all tested SUMO isoforms to lysine-127, but not to lysine-164, of ScPCNA. The SUMO isoforms AtSUMO1 and AtSUMO2, but not AtSUMO3, were found to form polymeric chains on ScPCNA due to a self-SUMOylation process. In a complementary approach, we analyzed both the SUMO isopeptidase activity and the pre-SUMO-processing capacity of the putative Arabidopsis SUMO proteases At1g60220, At1g10570, and At5g60190 using the known SUMO isopeptidases ScULP1, XopD, and ESD4 (At4g15880) as reference enzymes. Interestingly, At5g60190 exhibits no SUMO protease activity but processes the pre-form of Arabidopsis Rub1. The other five enzymes represent SUMO isopeptidases that show different substrate preferences. All these enzymes cleave AtSUMO1 and AtSUMO2 conjugates of ScPCNA, whereas only the putative bacterial virulence factor XopD is able to release AtSUMO3. In addition, all five enzymes cleave pre-AtSUMO1 and pre-AtSUMO2 peptides, but none of the proteins efficiently produce mature AtSUMO3 or AtSUMO5 molecules from their precursors.
A Heteromeric RNA-Binding Protein Is Involved in Maintaining Acrophase and Period of the Circadian Clock
Authors: Iliev Dobromir , Voytsekh Olga , Schmidt Eva-Maria , Fiedler Monika , Nykytenko Alla , Mittag Maria
Published: August 2006

The RNA-binding protein CHLAMY1 from the green alga Chlamydomonas reinhardtii consists of two subunits. One (named C1) contains three lysine homology motifs and the other (named C3) has three RNA recognition motifs. CHLAMY1 binds specifically to uridine-guanine-repeat sequences and its circadian-binding activity is controlled at the posttranslational level, presumably by time-dependent formation of protein complexes consisting of C1 and C3 or C1 alone. Here we have characterized the role of the two subunits within the circadian system by measurements of a circadian rhythm of phototaxis in strains where C1 or C3 are either up- or down-regulated. Further, we have measured the rhythm of nitrite reductase activity in strains with reduced levels of C1 or C3. In case of changes in the C3 level (both increases and decreases), the acrophase of the phototaxis rhythm and of the nitrite reductase rhythm (C3 decrease) was shifted by several hours from subjective day (maximum in wild-type cells) back towards the night. In contrast, both silencing and overexpression of C1 resulted in disturbed circadian rhythms and arrhythmicity. Interestingly, the expression of C1 is interconnected with that of C3. Our data suggest that CHLAMY1 is involved in the control of the phase angle and period of the circadian clock in C. reinhardtii.
Mutations in an Auxin Receptor Homolog AFB5 and in SGT1b Confer Resistance to Synthetic Picolinate Auxins and Not to 2,4-Dichlorophenoxyacetic Acid or Indole-3-Acetic Acid in Arabidopsis
Authors: Walsh Terence A. , Neal Roben , Merlo Ann Owens , Honma Mary , Hicks Glenn R. , Wolff Karen , Matsumura Wendy , Davies John P.
Published: August 2006

Although a wide range of structurally diverse small molecules can act as auxins, it is unclear whether all of these compounds act via the same mechanisms that have been characterized for 2,4-dichlorophenoxyacetic acid (2,4-D) and indole-3-acetic acid (IAA). To address this question, we used a novel member of the picolinate class of synthetic auxins that is structurally distinct from 2,4-D to screen for Arabidopsis (Arabidopsis thaliana) mutants that show chemically selective auxin resistance. We identified seven alleles at two distinct genetic loci that conferred significant resistance to picolinate auxins such as picloram, yet had minimal cross-resistance to 2,4-D or IAA. Double mutants had the same level and selectivity of resistance as single mutants. The sites of the mutations were identified by positional mapping as At4g11260 and At5g49980. At5g49980 is previously uncharacterized and encodes auxin signaling F-box protein 5, one of five homologs of TIR1 in the Arabidopsis genome. TIR1 is the recognition component of the Skp1-cullin-F-box complex associated with the ubiquitin-proteasome pathway involved in auxin signaling and has recently been shown to be a receptor for IAA and 2,4-D. At4g11260 encodes the tetratricopeptide protein SGT1b that has also been associated with Skp1-cullin-F-box-mediated ubiquitination in auxin signaling and other pathways. Complementation of mutant lines with their corresponding wild-type genes restored picolinate auxin sensitivity. These results show that chemical specificity in auxin signaling can be conferred by upstream components of the auxin response pathway. They also demonstrate the utility of genetic screens using structurally diverse chemistries to uncover novel pathway components.
Mitochondria-Associated Hexokinases Play a Role in the Control of Programmed Cell Death inNicotiana benthamiana
Authors: Kim Moonil , Lim Jeong-Hwa , Ahn Chang Sook , Park Kyoungsook , Kim Gyung Tae , Kim Woo Taek , Pai Hyun-Sook
Published: August 2006

Recent findings suggest a pivotal role for mitochondria-associated hexokinase in the regulation of apoptosis in animal cells. In this study, virus-induced gene silencing (VIGS) of a hexokinase-encoding Hxk1 caused necrotic lesions on leaves, abnormal leaf morphology, and retarded plant growth in Nicotiana benthamiana. Hxk1 was associated with the mitochondria, and this association required the N-terminal membrane anchor. VIGS of Hxk1 reduced the cellular glucose-phosphorylating activity to ∼31% of control levels without changing the fructose-phosphorylating activity and did not alter hexose phosphate content severely. The affected cells showed programmed cell death (PCD) morphological markers, including nuclear condensation and DNA fragmentation. Similar to animal cell apoptosis, cytochrome c was released into the cytosol and caspase-9– and caspase-3–like proteolytic activities were strongly induced. Furthermore, based on flow cytometry, Arabidopsis thaliana plants overexpressing Arabidopsis HXK1 and HXK2, both of which are predominantly associated with mitochondria, exhibited enhanced resistance to H2O2- and α-picolinic acid–induced PCD. Finally, the addition of recombinant Hxk1 to mitochondria-enriched fractions prevented H2O2/clotrimazole-induced cytochrome c release and loss of mitochondrial membrane potential. Together, these results show that hexokinase critically regulates the execution of PCD in plant cells, suggesting a link between glucose metabolism and apoptosis.
GA4 Is the Active Gibberellin in the Regulation ofLEAFYTranscription andArabidopsisFloral Initiation
Authors: Eriksson Sven , Böhlenius Henrik , Moritz Thomas , Nilsson Ove
Published: August 2006

Flower initiation in Arabidopsis thaliana under noninductive short-day conditions is dependent on the biosynthesis of the plant hormone gibberellin (GA). This dependency can be explained, at least partly, by GA regulation of the flower meristem identity gene LEAFY (LFY) and the flowering time gene SUPPRESSOR OF CONSTANS1. Although it is well established that GA4 is the active GA in the regulation of Arabidopsis shoot elongation, the identity of the GA responsible for the regulation of Arabidopsis flowering has not been established. Through a combination of GA quantifications and sensitivity assays, we show that GA4 is the active GA in the regulation of LFY transcription and Arabidopsis flowering time under short-day conditions. The levels of GA4 and sucrose increase dramatically in the shoot apex shortly before floral initiation, and the regulation of genes involved in GA metabolism suggests that this increase is possibly due to transport of GAs and sucrose from outside sources to the shoot apex. Our results demonstrate that in the dicot Arabidopsis, in contrast with the monocot Lolium temulentum, GA4 is the active GA in the regulation of both shoot elongation and flower initiation.
The Clp1 Protein Is Required for Clamp Formation and Pathogenic Development ofUstilago maydis
Authors: Scherer Mario , Heimel Kai , Starke Verena , Kämper Jörg
Published: August 2006

In the phytopathogenic fungus Ustilago maydis, pathogenic development is controlled by a heterodimer of the two homeodomain proteins bE and bW, encoded by the b-mating-type locus. We have identified a b-dependently induced gene, clampless1 (clp1), that is required for the proliferation of dikaryotic filaments in planta. We show that U. maydis hyphae develop structures functionally equivalent to clamp cells that participate in the distribution of nuclei during cell division. In clp1 mutant strains, dikaryotic filaments penetrate the plant cuticle, but development is stalled before the first mitotic division, and the clamp-like structures are not formed. Although clp1 is immediately activated upon b-induction on the transcriptional level, nuclear-localized Clp1 protein is first observed at the stage of plant penetration prior to the first cell division. Induced expression of clp1 strongly interferes with b-dependent gene regulation and blocks b-dependent filament formation and b-dependent cell cycle arrest. We speculate that the Clp1 protein inhibits the activity of the bE/bW heterodimer to facilitate the cell cycle progression during hyphal growth.
Tung Tree DGAT1 and DGAT2 Have Nonredundant Functions in Triacylglycerol Biosynthesis and Are Localized to Different Subdomains of the Endoplasmic Reticulum
Authors: Shockey Jay M. , Gidda Satinder K. , Chapital Dorselyn C. , Kuan Jui-Chang , Dhanoa Preetinder K. , Bland John M. , Rothstein Steven J. , Mullen Robert T. , Dyer John M.
Published: August 2006

Seeds of the tung tree (Vernicia fordii) produce large quantities of triacylglycerols (TAGs) containing ∼80% eleostearic acid, an unusual conjugated fatty acid. We present a comparative analysis of the genetic, functional, and cellular properties of tung type 1 and type 2 diacylglycerol acyltransferases (DGAT1 and DGAT2), two unrelated enzymes that catalyze the committed step in TAG biosynthesis. We show that both enzymes are encoded by single genes and that DGAT1 is expressed at similar levels in various organs, whereas DGAT2 is strongly induced in developing seeds at the onset of oil biosynthesis. Expression of DGAT1 and DGAT2 in yeast produced different types and proportions of TAGs containing eleostearic acid, with DGAT2 possessing an enhanced propensity for the synthesis of trieleostearin, the main component of tung oil. Both DGAT1 and DGAT2 are located in distinct, dynamic regions of the endoplasmic reticulum (ER), and surprisingly, these regions do not overlap. Furthermore, although both DGAT1 and DGAT2 contain a similar C-terminal pentapeptide ER retrieval motif, this motif alone is not sufficient for their localization to specific regions of the ER. These data suggest that DGAT1 and DGAT2 have nonredundant functions in plants and that the production of storage oils, including those containing unusual fatty acids, occurs in distinct ER subdomains.
Oscillatory Increases in Alkalinity Anticipate Growth and May Regulate Actin Dynamics in Pollen Tubes of Lily
Authors: Lovy-Wheeler Alenka , Kunkel Joseph G. , Allwood Ellen G. , Hussey Patrick J. , Hepler Peter K.
Published: August 2006

Lily (Lilium formosanum or Lilium longiflorum) pollen tubes, microinjected with a low concentration of the pH-sensitive dye bis-carboxyethyl carboxyfluorescein dextran, show oscillating pH changes in their apical domain relative to growth. An increase in pH in the apex precedes the fastest growth velocities, whereas a decline follows growth, suggesting a possible relationship between alkalinity and cell extension. A target for pH may be the actin cytoskeleton, because the apical cortical actin fringe resides in the same region as the alkaline band in lily pollen tubes and elongation requires actin polymerization. A pH-sensitive actin binding protein, actin-depolymerizing factor (ADF), together with actin-interacting protein (AIP) localize to the cortical actin fringe region. Modifying intracellular pH leads to reorganization of the actin cytoskeleton, especially in the apical domain. Acidification causes actin filament destabilization and inhibits growth by 80%. Upon complete growth inhibition, the actin fringe is the first actin cytoskeleton component to disappear. We propose that during normal growth, the pH increase in the alkaline band stimulates the fragmenting activity of ADF/AIP, which in turn generates more sites for actin polymerization. Increased actin polymerization supports faster growth rates and a proton influx, which inactivates ADF/AIP, decreases actin polymerization, and retards growth. As pH stabilizes and increases, the activity of ADF/AIP again increases, repeating the cycle of events.
Uncertainties in Canning Process Calculations
Authors: HICKS E. W.
Published: August 2006

The nature of safety factors in canning processes and the uncertainties in calculating lethal values are discussed. The nature, extent, and consequences of these uncertainties are examined. Uncertainties in both the thermal data, obtained from heat penetration measurements, and the bacteriological data contribute significantly to the over‐all uncertainty, that in bacteriological data generally being greater. Although experimental error may be large, most of the uncertainty in thermal data is due to real variations from can to can. These uncertainties should be taken into account whenever calculations are made in canning processes, particularly in deciding the safety factor to employ in any particular case.
The Volatile Flavor Substances of Celery
Authors: GOLD HARVEY J. , WILSON CHARLES W.
Published: August 2006

The isolation and identification of the volatile compounds of celery are described. Non‐linear temperature‐programmed gas chromatography was found to give resolution superior to that of either isothermal operation or linear temperature programming. The identification of 24 compounds from celery is reported. Of the 38 compounds thus far identified from celery distillates, the following six compounds are primarily responsible for the characteristic flavor and aroma of celery: 3‐isobutylidene‐3a,4‐dihydrophthalide; 3‐isovalidene‐ 3a,4‐dihydrophthalide; 3‐isobutylidene phthalide; 3‐isovalidene phthalide; cis‐3‐hexen‐l‐yl pyruvate; and diacetyl. The phthalide derivatives are also implicated in the occurrence of certain celery off‐flavors reported in the literature.
Nutrient Content of Morel Mushroom Mycelium: Amino Acid Composition of the Protein
Authors: LITCHFTELD J. H. , VELY V. G. , OVERBECK R. C.
Published: August 2006

Mycelia of three species of morel mushrooms, Morchella crassipes, M. esculenta, and M. hortensis, were grown in submerged culture in a glucose‐ammonium phosphate‐corn steep liquor medium. The dried mycelia were subjected to proximate analyses and amino acid determinations. A commercial morel mushroom powder was also analyzed for the same constituents. The dry samples contained 22.8–51.0% protein and 2.18–7.55% fat, depending upon the species. Amino aeid contents were similar to those reported in the literature for other fungi.
Polyphenoloxidase in Bartlett Pearsa
Authors: TATE J. N. , LUH B. S. , YORK G. K.
Published: August 2006

The characteristics of polyphenoloxidase in Bartlett pears were investigated. In a citrate‐phosphate buffer containing 0.03M catechol as the substrate, activity of the pear polyphenoloxidase was greatest in the pH range 5.8‐6.4, being optimum at pH 6.2. The Michaelis constant of the enzyme was 0.048M at pH 6.2 in a citrate‐phosphate buffer. It was active only on phenolic compounds having an ortho‐diphenolic configuration. Neither the meta‐ nor para‐dihydroxy phenolic compounds nor phenol was attacked. The energy of activation for pear polyphenoloxidase on catechol was 4.9 kcal per mole. Oxygen was necessary for browning of catechol to take place in the presence of pear polyphenoloxidase, and the activity was greatly decreased when the concentration of oxygen in the reaction mixture was lowered. Diethyldithiocarbamate, a copper‐chelating agent, and phloroglucinol, a competitive inhibitor, reduced browning markedly, but ascorbic acid was most effective of all. It was noted that ascorbic acid acts as an antioxidant rather than as a true enzyme inhibitor. Iodoacet‐amide, a sulfhydryl inhibitor, had no effect on rate of browning. Methods for preventing brown discoloration in canned pears are discussed.
The Fatty Acid Composition of Liver Lipids from Rats Raised on Pork Rationsa,b
Authors: TINSLEY IAN J.
Published: August 2006

The liver lipid fatty acid composition of animals raised on pork rations was determined and compared with that of animals raised on a stock ration. The pork rations contained approximately 25% crude lipid, the proportion of oleic acid being 46–50%. The relation between the dietary and liver lipid fatty acid compositions was evaluated, with the most striking relationship being that between dietary and liver lipid oleate/linoleate ratios. The tissue levels of oleic, linoleic, and arachidonic acids provided supporting evidence for the existence of a competitive effect of oleic acid in the conversion of linoleic to arachidonic acid. The results suggest that the dietary oleate/linoleate ratio is of importance in essential fatty acid nutrition in rations containing appreciable quantities of oleic acid. The sex variable, as it applies to the relation between dietary and liver lipid, was also evaluated.
Organic Acids in Citrus Fruits. I. Varietal Differencesa
Authors: CLEMENTS ROBERT L.
Published: August 2006

Organic acids were determined in juices and peels of mature fruits of Washington Navel and Valencia oranges, grapefruit, lemon, tangerine, and Palestine sweet lime. Juices and peels were freeze‐dried, and organic acids were determined by silicic‐acid chromatography. Cation‐exchange resin in the hydrogen form was used for acidification of peel prior to extraction of acids with methanol. Citric acid predominated in all juices except that of the sweet lime (in which citrate level was so low that malate exceeded it). Malate occurred in all juices in low but measurable concentrations. Oxalate predominated in the peels, but in the lime, malonate appeared in equivalent amounts. Malonate appeared in all peels in measurable amounts, and in some peels was exceeded only by oxalate. Malic and citric acids were also determined in each peel. At least 15 peaks appeared with each peel, and paper chromatography of the effluents indicated the presence of more than one component in several peaks.
Isolation and Characterization of Low‐Density Lipoproteins in Native Egg Yolk Plasma
Authors: SAARI A. , POWRIE W. D. , FENNEMA O.
Published: August 2006

The composition of water‐washed yolk granules was different from that of yolk plasma. The lipid content of the granules was about 35%, in contrast to that of plasma (81%). Concentrations of phospholipid, phosphorus‐containing protein, and protein nitrogen were not the same for the granules and plasma. A method was developed for the isolation of two ultracentrifugally distinguishable fractions, LPL1, and LPL2, from yolk plasma by a differential flotation procedure. The differences in composition of LPL1 and LPL2 were small but significant. LPL1 contained about 89% lipid, whereas LPL2 was about 86% lipid. LPL1 and LPL2 behaved differently when treated by heat and a proteolytic enzyme. A major yolk steroid, isolated by digitonin precipitation, had a melting point and infrared spectrum similar to those for cholesterol.
Chromatographic Fractionation of Sarcoplasmic Proteins of Beef Skeletal Muscle on Ion‐Exchange Cellulosea,b
Authors: FUJIMAKI M. , DEATHERAGE F. E.
Published: August 2006

Sarcoplasmic proteins from beef skeletal muscle were fractionated by chromatography on ion‐exchange cellulose (cellulose phosphate and diethyl‐aminoethyl cellulose) at pH 5 and 9.3. From effluent diagrams of sarcoplasma from muscle immediately after slaughter, at least 14 fractions were recognized, and some of them were identified with known proteins by assays for enzymic activities. The numbers and levels of eluted peaks in the effluent diagram were found to decrease with storage (aging) of muscle and freeze‐drying of sarcoplasma; these decreases are perhaps due to denaturation. Proteins in solutions appear to be more completely separated by chromatography when different combinations of ion‐exchange cellulose are used.
Color Deterioration in Frozen French Beans (Phaseolus vulgaris)
Authors: WALKER G. C.
Published: August 2006

Examination of 12 commercial frozen bean packs showed two forms of color deterioration. The first resulted in conversion of chlorophyll to pheophytin, and the second caused destruction of both chlorophyll and pheophytin. It is shown that both forms of degradation may be related to the process of fat peroxidation. The conversion of chlorophyll to pheophytin may occur during the anaerobic initiation stage of fat peroxidation. Destruction may occur during the aerobic propagation stage.
Apple Juice Volatilesa
Authors: MacGREGOR D. R. , SUGISAWA H. , MATTHEWS J. S.
Published: August 2006

Thirty compounds in the volatile fraction of McIntosh apple juice were isolated and identified. Material for gas chromatography was prepared by concentrating volatiles tenfold in a rising film evaporator and extracting with ethyl chloride. The compounds were identified by comparing retention volumes and infrared spectra with those of known compounds. Volatile components tentatively identified on the basis of their infrared spectra and retention data included 4 aldehydes, 1 ketone, 11 alcohols, 10 esters, and 4 fatty acids. In addition, 7 peaks were found but not identified. A variety of column packings and operating conditions were necessary to obtain reasonable separation of the components isolated.
The Long‐Term Effect of Electrical Stimulation on the Post‐Mortem Fall of pH in the Muscles of Landrace Pigs
Authors: HALLUND O. , BENDALL J. R.
Published: August 2006

It has been shown previously, in a series of experiments on the post‐mortem fall of pH in the muscles of Danish Landrace pigs, that the animals can be broadly divided into two groups, differing in rate of fall. One gives samples with low rates, called A, and the other with rates twice as high, called B.

The present experiments show that the slow fall of pH in group A muscles can be converted to a quick fall by subjecting excised samples to a short tetanus. This accelerating effect of electrical stimulation lasts during the whole course of the pH‐time curves, and is easily distinguished from the well‐known short‐term effect, characteristic of this and many other types of muscle. Although the latter can be clearly demonstrated in rabbit muscle, for instance, the subsequent long‐term acceleration is entirely absent. The latter must therefore be considered a new and hitherto undescribed phenomenon, so far reported only for the pig. It is due to an induced higher ATP‐ase activity, although the mechanism is obscure.

These findings open up a new approach in the search for the Cause of the rapid postmortem fall of pH characteristic of pig muscles which subsequently yield pale and watery pork.
The Growth and Persistence of Staphylococcus aureus in Milk and Broth Substrates
Authors: WALKER G. C. , HARMON L. G.
Published: August 2006

The growth of two strains of coagulase‐positive Staphylococcus aureus was measured in whole and skimmilk and in broth at 5, 10, 22, 30 and 37° There was a continuous decrease in population in all media at 5°. The medium had little effect on the duration of the logarithmic growth phase which varied from 12 hr at 37° to 20 days at 10°. Typical generation times in whole milk varied from 1642 min at 10° to 45 min at 37°. At 10 and 22° there was no statistically significant difference in the generation times among media or between strains. At, 30 and 37° there was no significant difference between the generation times in skimmilk and whole milk, but the generation time was significantly shorter (at the 5% level) in the broth than in the milks. The cultures maintained a longer stationary growth phase and were more persistent in broth and skimmilk than in whole milk. More rapid decreases in population in the whole milk were attributed to the toxicity of fatty acids released by the lipase of S. aureus. The decline in pH of the substrate was approximately proportional to the increase in population.
Enzymatic Reduction of Metmyoglobin by Ground Beef
Authors: STEWART MARGARET R. , HUTCHINS BOBBIE K. , ZIPSER MARELYNN W. , WATTS BETTY M.
Published: August 2006

A method is described for estimating the ability of ground meat to reduce metmyoglobin enzymatically. The method involves a complete oxidation of all pigments to metmyoglobin by the addition of ferricyanide, followed by measurement of metmyoglobin reduction by the meat in 1 hr. The work was confined to beef rib eye muscle. Metmyoglobin‐reducing activity (MRA) showed great fluctuations in rib eyes from different animals. It was correlated with total pigment. In any one sample of meat, MRA increased with pH from pH 5.1 to 7.1 and with temperature from 3°C to 35°C. It declined only slightly in whole cuts of meat stored for several days in the refrigerator, but much more rapidly in stored ground meat. Chlortetracycline did not interfere with MRA, but 5% salt completely inhibited it. A possible reductive mechanism is discussed briefly.
Conversion of Valencene to Nootkatone
Authors: HUNTER G. L. K. , BROGDEN W. B.
Published: August 2006

Nootkatone, an important flavoring constituent in grapefruit, has been synthesized from the sesquiterpene hydrocarbon valencene. Valencene, which is isolated from orange oil, was oxidized with tert‐butyl chromate to yield a sesquiterpene ketone having the same physical properties as the natural nootkatone.
The Solubility of Intramuscular Collagen in Meat Animals of Various Ages
Authors: HILL F.
Published: August 2006

The percentage of total intramuscular collagen solubilized by heating in 1/4‐strength Ringer's solution, muscles from 98 cattle, 15 sheep, and 9 pigs at 77°C for 1 hour decreased as chronological age increased. Total intramuscular collagen was high in very young (8‐9 weeks) bo vines and in two of the three very old (7‐15 years) bovines studied. In the age range of 16 weeks to d1/2 years, variation in total bovine intramuscular collagen was wide. There was no indication of a systematic increase as age increased. The results provide strong presumptive evidence of an increase with age in the number or strength of the cross links of intramuscular collagen and furnish an acceptable explanation as to why total amounts of intramuscular collagen are inadequate to explain toughness associated with increasing chronological age.
Sensory and Chromatographic Analysis of Mixtures Formulated from Pure Odorants
Authors: KENDALL DAVID A. , NEILSON ANNE J.
Published: August 2006

Continuing the leads from previously published studies of four chemicals having different odors hut similar molecular weights and boiling points, this work centers on sensory examinations of the vapors over essentially water solutions of GLC‐purified anethol, geranial, methyl salicylate, and safrol. Experienced profile‐trained panelists examined the odors from two‐ and four‐component mixtures of the odorants at multiple decimal fractions of odor‐recognition threshold concentrations in terms of molarity. Findings for the two‐component mixtures showed these possible phenomena: 1) intensification of one odorant with suppression of the other; 2) increase in total intensity of odor; 3) decrease in total intensity with development of a different odor character (i.e., blending); and 4) infrequently, no describable difference (i.e., no interaction). Interactions were also found for the four‐component systems, which, because of greater complexity, more frequently showed tendencies toward blending. Sucrose, salt, and mono‐sodium glutamate were added separately at their food‐use levels (respectively 10, 1, and 0.1%) to a quaternary mixture and were found to have different effects. Sucrose emphasized the mixture's lemon‐candy identity; salt clouded the solution and emphasized its root beer character; MSG disrupted the blend. In addition to these nonvolatiles, two odorous substances known to have odor‐blending or fixative properties were examined for recognition threshold and effect on the quaternary blend when added at 1/10 their threshold concentrations. Nonalactone, at 1/10 10−9 g/ml, increased the soapy‐oily character of the geranial. Exaltone, at 1/10 10−9 g/ml, blended the odor still further. The minimum change in concentration to give a detectable difference in odor strength (just noticeable difference) was determined for geranial at the profile intensity range of moderate. The jnd was found to he of the order of 100.2, representing about a 60% increase in concentration, which coincides with the 58% increase cited by other workers.
Pectin Methyl Esterases of the Banana. Purification and Properties
Authors: HULTIN H. O. , SUN BONNIE , BULGER J.
Published: August 2006

Earlier, three fractions of pectin methyl esterase (PME) had been obtained from the pulp of the banana by differential extraction. The crude enzyme preparations have now been purified further by ammonium sulfate fractionation and ion‐exchange chromatography on columns of DEAE‐ and CM‐cellulose. Each fraction has a unique behavior on the ion‐exchange columns. Additional criteria have been established to differentiate the fractions. These include response to cations, inorganic phosphate, nucleotides, and sucrose, as well as differences in initial reaction kinetics, resistance to end‐product inhibition, and cold stabilities. The possibility of interconversion between fractions is discussed; Fractions I and II may be converted by treatment with 3.5 × 10−4M sodium dodecyl sulfate to forms resembling Fraction III as determined by pH‐activity spectra.
Surface Activity of Yolk, Plasma and Dispersions of Yolk Fractions
Authors: VINCENT R. , POWRIE W. D. , FENNEMA O.
Published: August 2006

Undiluted yolk, plasma, and a 4.8% livetin solution had surface tensions of about 44 dynes/cm and interfacial tensions of around 5 dynes/cm. Extensive dilution of the yolk and plasma with either water or 10% NaCl did not bring about marked decreases in the activity of the surfaces. Rehydrated dried yolk had surface energy values similar to those for yolk. Granule suspensions, diluted with water and 10% Nail, had high surface and interfacial tensions. A yolk phospholipid fraction reduced the surface energy of sols to very low values. The contributions of proteins in a livetin fraction and of phospholipids to the surface properties of yolk are discussed.
Irradiation of Mangoes. I. Radiation‐induced Delay in Ripening of Alphonso Mangoes
Authors: DHARKAR S. D. , SAVAGAON K. A. , SRIRANGARAJAN A. N. , SREENIVASAN A.
Published: August 2006

Extension of storage life of unripe and mature Alphonse mangoes could he achieved at an optimum dose of 25 krads when irradiated under air, nitrogen, or carbon dioxide. Nitrogen atmosphere during irradiation is of some advantage in minimizing changes in organoleptic quality, ascorbic acid, and carotenoids, and at the same time allowing the least spoilage of fruit. Judging from skin color and fruit firmness, a six‐day delay in ripening could be expected in fruits irradiated with 25 krads under nitrogen or air. Radiation effect on fruit skin is more prominent in terms of inhibition in chlorophyll disappearance and earotenoid formation than in ripening changes in the meat of the fruit.
Kinetic Behavior and Mechanism of Inhibition in the Maillard Reaction. I. Kinetic Behavior of the Reaction Between D‐Glucose and Glycine
Authors: SONG PILL‐SOON , CHICHESTER C. O. , STADTMAN F. H.
Published: August 2006

The kinetic behavior of the Maillard reaction between D‐glucose and glycine is discussed, and apparent rate constants–kl, from the induction period of the reaction, and Ka. t, from the steady‐phase formation of melanoidins– are estimated. The free energies of activation for two steps with corresponding rate constants K1 and ka t are respectively found to be 26.5 and 26.1 kcal mole‐1. Both steps have unfavorable negative entropy of activation. The overall rate expression is

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where I represents intermediates, g and G respectively glycine and glucose, B the brown products, and k's the rate constants. On the basis of kinetic considerations, hydroxymethyl furfural is ruled out as a major intermediate in the Maillard reaction.
Composition of Raw and Roasted Lamb and Mutton I. Physical and Proximate Composition
Authors: MURPHY ELIZABETH W. , TOEPFER EDWARD W. , MARSH ANNE C. , HAGAN SUSIE N.
Published: August 2006

Sixty cuts each of raw and roasted rib‐loin and of raw and roasted leg of lamb and mutton, obtained from 118 carcasses, were separated into their physical components. Proximate composition was determined on the resulting separable lean, separable fat, and drippings. Correlation coefficients between weight of cut and each physical and proximate component were determined, and the effects of weight of cut and of roasting on the partitioning of nutrients among the separated portions were examined.

With increasing weight of cut, percentage of separable fat and of drippings increased, and percentage of separable lean and of evaporation loss decreased. For rib‐loins, as weight of cut increased, the proportion of bone and waste, and the percentages of moisture, protein, and ash in all separable portions decreased, but the percentage of lipids increased. Relations were similar in leg cuts, except that percentage of bone and waste, percentage of protein in raw or roasted separable lean, and moisture content of drippings did not change significantly.

Separable lean, raw or roasted, contained about 90% of the protein and moisture of the entire cut, but only about a quarter of the total lipids. Lean from raw cuts contained about 90% of the ash of the total cut, but lean from cooked cuts contained only about two‐thirds of the ash of the entire cut. As weight of cut increased, the amounts of proximate components in the lean decreased in proportion to those amounts in the total cut.
Volatile Components of Peach. II
Authors: SEVENANTS M. R. , JENNINGS W. G.
Published: August 2006

A volatile‐essence concentrate isolated from the Red Globe variety of freestone peaches and already partially characterized, was further fractionated by newly developed gas chromatographic techniques of repetitive ultra micro collections and reinjections. An adapted micro‐cavity infrared cell permitted infrared analysis of these minute fractions, which were then identified by comparison with known compounds. Synthesis and ultra‐micro vapor‐phase hydrogenation were used to characterize compounds for which standards could not he obtained. Compounds identified include hexyl formate, hexyl acetate, tram‐2‐hexenyl acetate, hexyl alcohol, trans‐2‐hexenel‐01, isovaleric acid, ethyl benzoate, benzyl acetate, caproic acid, ganzma‐heptalactone, gamma‐nonalactone, hexyl benzoate, and an alpha‐pyrone.
Methyl Anthranilate Content of Citrus Honey
Authors: WHITE JONATHAN W.
Published: August 2006

A photometric method for determination of methyl anthranilate (MA) was adapted for honey. Twenty‐one citrus honeys from 3 states and 5 crops averaged 2.87 μg/g (range 0.84–4.37). For 12 non‐citrus honeys, apparent MA content averaged 0.07 μg/g (range 0.00–0.28).
Factors Affecting Collagen Solubility in Bovine Muscles
Authors: HERRING H. K. , CASSENS R. G. , BRISKEY E. J.
Published: August 2006

SUMMARY— Solubility of intramuscular collagen was studied as affected by chronological maturity in 15 bovine longissimus dorsi and 15 semimembranosus muscles and as affected by post‐mortem contraction state in the semitendinosus of 7 animals. Collagen solubility decreased significantly with each advancing maturity group in both longissimus dorsi and semimembranosus muscles. Collagen solubility was also higher (P < 0.05) in the longissimus dorsi than in the semimembranosus, except in the E maturity group. It was also related to panel tenderness in both muscles (r = 0.77 and 0.81 (P < 0.01) for longissimus dorsi and semimembranosus muscles, respectively. However, within‐maturity group correlations of solubility of collagen and tenderness were low and nonsignificent.

Collagen content did not differ significantly in longissimus dorsi muscles of animals of A, B, and E maturity groups; however, the semimembranosus had more collagen (P < 0.05) in E than in A and B maturity groups. Collagen content was not related (P > 0.05) to panel tenderness in either muscle (r =−0.42 and −0.48 for longissimus dorsi and semimembranosus, respectively). Neither collagen solubility nor collagen content was significantly affected by post‐mortem contraction state. Furthermore, collagen solubility did not increase significantly with post‐mortem aging up to ten days.
A New Aroma‐Bearing Substance from Shiitake, an Edible Mushroom
Authors: WADA SHYOZO , NAKATANI HIROMI , MORITA KATSURA
Published: August 2006

SUMMARY— Investigations on the physico‐chemical properties and a sensory evaluation as a component of Shiitake flavor were carried out with lenthionine, a substance which was isolated from dried Shiitake mushroom. Lenthionine is practically insoluble in water but soluble in non‐polar solvents. Its stability in an aqueous solution changes greatly with the pH of the solution.

Lenthionine was identified as a significant component in the aroma of Shiitake mushroom and its detectable threshold level is at a concentration between 0.27 and 0.53 porn in water. This new aroma‐bearing substance will be used as a flavor additive in various foods.
Pectic Enzymes and Development of the Pear (Pyrus communis)
Authors: NAGEL C. W. , PATTERSON M. E.
Published: August 2006

SUMMARY—

Changes in firmness, protein, pectinesterase (PE) and polygalacturonase (PG) were followed during enlargement, maturation, and abnormal ripening of the Bartlett pear (Pyrus communis) on the tree. Although the PE activity per pear increased during maturation, with a good correlation with total weight (r= 0.93 and 0.87 for 1962 and 1963), the amount of activity per gram fresh weight and per milligram protein decreased. There was a high correlation between PE activity and protein (r= 0.84 and 0.91 for 1962 and 1963). The specific activity of the enzyme decreased during maturation. As the fruit matured and ripened on the tree, the percent recovery of PE decreased. The use of polyvinylpyrrolidone in the extraction procedure to adsorb the phenolic compounds counteracted this trend. It was concluded that the small changes in PE activity could not account for the changes in esterification of pectin observed by other investigators. Variable results were obtained with the PG assays. Weak PG activity was observed in the immature fruit in 1962 and 1963. No activity was observed in 1966, even in the presence of polyvinylpyrrolidone.
Molecular Properties of Post‐Mortem Muscle. 4. Effect of Temperature on Adenosine Triphosphate Degradation, Isometric Tension Parameters, and Shear Resistance of Bovine Muscle
Authors: BUSCH W. A. , JR. F. C. PARRISH , GOLL DARREL E.
Published: August 2006

SUMMARY– Investigations were conducted on the effect of three storage temperatures, 2°, 16°, and 37°, on the changes and relationships of certain chemical and physical properties of post‐mortem bovine semitendinosus and psoas muscle. Post‐mortem muscle shortening was measured with the isometer. Isometric tension development was maximal at 2°, minimal at 16°, and at 37° tension was approximately one‐half that developed at 2°. The large tension development at 2° very likely originates from the same events as those in “cold shortening.” Differences in isometric tension parameters were noted between muscles in that psoas muscle developed tension and lost the ability to maintain tension more quickly than did the semitendinosus. Loss of ability to maintain tension was observed only at 2°, and this could correspond to a “resolution” of rigor mortis. Adenosine triphosphate (ATP) degradation was measured by two methods, ammonia production and bioluminescent enzymic method; the bioluminescent method proved to be the more satisfactory. A common relationship was observed between pH and ATP for both muscles and the three temperatures studied. No direct relationship was found between ATP degradation and shear resistance with the possible exception of muscle stored at 37°. Isometric tension parameters and shear resistance were related somewhat at 2° in semitendinosus muscle, but no relationship existed at 16° and 37°. Although considerable tension developed in psoas and semitendinosus muscle at 37°, shear resistance values decreased continuously, indicating that factors other than shortening are more important at high temperature and that these factors are temperature‐dependent.

The role of ATP degradation in tension development was difficult to interpret, since at 2°, only a small change occurred in ATP level during large tension development, and the level of ATP at 2° did not differ from ATP level in muscle stored at 16° which developed little tension.

Differences in post‐mortem muscle shortening at 2 and 37 are discussed.
A Quantitative and Morphological Study of Bovine Longissimus Fat Cells
Authors: MOODY W. G. , CASSENS R. G.
Published: August 2006

SUMMARY— A quantitative and morphological study was made of bovine fat cells from three marbling groups of longissimus muscle. Tracings on acetate paper were made of the visual marbling depots and the area measured at three positions with an ocular grid for both size and distribution of fat cells. Comparisons were also made of subcutaneous, intermuscular and intramuscular fat cell size. Intrafiber lipid accumulation was observed and the average number of red fibers per bundle determined. These results indicate that traceable intramuscular fat is not a good measure of total intramuscular fat. There did not appear to be a consistent medial, central and lateral marbling pattern among the three marbling groups; however, significant differences were apparent within groups. Fat cell size increased with increases in cell mass, marbling and total chemical fat of the muscle.

Fat cells accumulated and grew in close proximity to portions of the circulatory system. Lipid deposits adjacent to the muscle contained larger fat cells than was evident in the extrafascicular spaces within the muscle. Intrafiber lipid was readily apparent in approximately 35% of the muscle fibers and probably represented either mitochondria or triglyceride. The interrelationship of subjective marbling scores, chemically determined fat, fat cell size, fat cell distribution and intrafiber lipid characteristics are complex and require complete investigation before the association of muscle fat and meat quality can be resolved.
Determination of Flavor Threshold Levels and Sub‐Threshold, Additive, and Concentration Effects
Authors: KEITH ELIZABETH S. , POWERS JOHN J.
Published: August 2006

SUMMARY— The flavor threshold concentrations were determined for 23 compounds composing an artificial peach beverage base. The threshold levels ranged from 52 ppm to 0.4 ppb. The threshold values were used in sub‐threshold, additive sub‐threshold, and concentration trials. Sub‐threshold and additive sub‐threshold effects resulted from only a few of the flavor combinations tried. Change in concentration of one compound in a mixture of six compounds was not readily detectable organoleptically. The difference in concentration could be detected gas chromatographically, but only if the mixtures were extracted with pentane and concentrated.

By dividing the respective threshold values into the amount of each compound present in the beverage, a factor was calculated, called the “unit flavor base,” which indicated the relative importance of each compound as a flavor substance in the peach beverage. By dividing the gas chromatographic peak heights by the respective threshold values, gas chromatographic response was weighted for flavor importance. When the unit flavor base and weighted gas chromatographic response were converted into logarithms, the relation between the values was nearly linear. The correlation coefficient was 0.8691 (significant @ 0.01).