bluuebunny/crossref_metadata_2025 huggingface dataset:
Ectopic Expression of ABSCISIC ACID 2/GLUCOSE INSENSITIVE 1 in Arabidopsis Promotes Seed Dormancy and Stress Tolerance
Authors: Lin Pei-Chi , Hwang San-Gwang , Endo Akira , Okamoto Masanori , Koshiba Tomokazu , Cheng Wan-Hsing
Published: December 2006

Abscisic acid (ABA) is an important phytohormone that plays a critical role in seed development, dormancy, and stress tolerance. 9-cis-Epoxycarotenoid dioxygenase is the key enzyme controlling ABA biosynthesis and stress tolerance. In this study, we investigated the effect of ectopic expression of another ABA biosynthesis gene, ABA2 (or GLUCOSE INSENSITIVE 1 [GIN1]) encoding a short-chain dehydrogenase/reductase in Arabidopsis (Arabidopsis thaliana). We show that ABA2-overexpressing transgenic plants with elevated ABA levels exhibited seed germination delay and more tolerance to salinity than wild type when grown on agar plates and/or in soil. However, the germination delay was abolished in transgenic plants showing ABA levels over 2-fold higher than that of wild type grown on 250 mm NaCl. The data suggest that there are distinct mechanisms underlying ABA-mediated inhibition of seed germination under diverse stress. The ABA-deficient mutant aba2, with a shorter primary root, can be restored to normal root growth by exogenous application of ABA, whereas transgenic plants overexpressing ABA2 showed normal root growth. The data reflect that the basal levels of ABA are essential for maintaining normal primary root elongation. Furthermore, analysis of ABA2 promoter activity with ABA2∷β-glucuronidase transgenic plants revealed that the promoter activity was enhanced by multiple prolonged stresses, such as drought, salinity, cold, and flooding, but not by short-term stress treatments. Coincidently, prolonged drought stress treatment led to the up-regulation of ABA biosynthetic and sugar-related genes. Thus, the data support ABA2 as a late expression gene that might have a fine-tuning function in mediating ABA biosynthesis through primary metabolic changes in response to stress.
Two Arabidopsis Genes (IPMS1 and IPMS2) Encode Isopropylmalate Synthase, the Branchpoint Step in the Biosynthesis of Leucine
Authors: de Kraker Jan-Willem , Luck Katrin , Textor Susanne , Tokuhisa James G. , Gershenzon Jonathan
Published: December 2006

Heterologous expression of the Arabidopsis (Arabidopsis thaliana) IPMS1 (At1g18500) and IPMS2 (At1g74040) cDNAs in Escherichia coli yields isopropylmalate synthases (IPMSs; EC 2.3.3.13). These enzymes catalyze the first dedicated step in leucine (Leu) biosynthesis, an aldol-type condensation of acetyl-coenzyme A (CoA) and 2-oxoisovalerate yielding isopropylmalate. Most biochemical properties of IPMS1 and IPMS2 are similar: broad pH optimum around pH 8.5, Mg2+ as cofactor, feedback inhibition by Leu, K  m for 2-oxoisovalerate of approximately 300 μ  m, and a V  max of approximately 2 × 103  μmol min−1 g−1. However, IPMS1 and IPMS2 differ in their K  m for acetyl-CoA (45 μ  m and 16 μ  m, respectively) and apparent quaternary structure (dimer and tetramer, respectively). A knockout insertion mutant for IPMS1 showed an increase in valine content but no changes in Leu content; two insertion mutants for IPMS2 did not show any changes in soluble amino acid content. Apparently, in planta each gene can adequately compensate for the absence of the other, consistent with available microarray and reverse transcription-polymerase chain reaction data that show that both genes are expressed in all organs at all developmental stages. Both encoded proteins accept 2-oxo acid substrates in vitro ranging in length from glyoxylate to 2-oxohexanoate, and catalyze at a low rate the condensation of acetyl-CoA and 4-methylthio-2-oxobutyrate, i.e. a reaction involved in glucosinolate chain elongation normally catalyzed by methylthioalkylmalate synthases. The evolutionary relationship between IPMS and methylthioalkylmalate synthase enzymes is discussed in view of their amino acid sequence identity (60%) and overlap in substrate specificity.
Silverleaf Whitefly Induces Salicylic Acid Defenses and Suppresses Effectual Jasmonic Acid Defenses
Authors: Zarate Sonia I. , Kempema Louisa A. , Walling Linda L.
Published: December 2006

The basal defenses important in curtailing the development of the phloem-feeding silverleaf whitefly (Bemisia tabaci type B; SLWF) on Arabidopsis (Arabidopsis thaliana) were investigated. Sentinel defense gene RNAs were monitored in SLWF-infested and control plants. Salicylic acid (SA)-responsive gene transcripts accumulated locally (PR1, BGL2, PR5, SID2, EDS5, PAD4) and systemically (PR1, BGL2, PR5) during SLWF nymph feeding. In contrast, jasmonic acid (JA)- and ethylene-dependent RNAs (PDF1.2, VSP1, HEL, THI2.1, FAD3, ERS1, ERF1) were repressed or not modulated in SLWF-infested leaves. To test for a role of SA and JA pathways in basal defense, SLWF development on mutant and transgenic lines that constitutively activate or impair defense pathways was determined. By monitoring the percentage of SLWF nymphs in each instar, we show that mutants that activate SA defenses (cim10) or impair JA defenses (coi1) accelerated SLWF nymphal development. Reciprocally, mutants that activate JA defenses (cev1) or impair SA defenses (npr1, NahG) slowed SLWF nymphal development. Furthermore, when npr1 plants, which do not activate downstream SA defenses, were treated with methyl jasmonate, a dramatic delay in nymph development was observed. Collectively, these results showed that SLWF-repressed, JA-regulated defenses were associated with basal defense to the SLWF.
Transgenic Tobacco Plants Overexpressing Chloroplastic Ferredoxin-NADP(H) Reductase Display Normal Rates of Photosynthesis and Increased Tolerance to Oxidative Stress
Authors: Rodriguez Ramiro E. , Lodeyro Anabella , Poli Hugo O. , Zurbriggen Matias , Peisker Martin , Palatnik Javier F. , Tognetti Vanesa B. , Tschiersch Henning , Hajirezaei Mohammad-Reza , Valle Estela M. , Carrillo Néstor
Published: December 2006

Ferredoxin-NADP(H) reductase (FNR) catalyzes the last step of photosynthetic electron transport in chloroplasts, driving electrons from reduced ferredoxin to NADP+. This reaction is rate limiting for photosynthesis under a wide range of illumination conditions, as revealed by analysis of plants transformed with an antisense version of the FNR gene. To investigate whether accumulation of this flavoprotein over wild-type levels could improve photosynthetic efficiency and growth, we generated transgenic tobacco (Nicotiana tabacum) plants expressing a pea (Pisum sativum) FNR targeted to chloroplasts. The alien product distributed between the thylakoid membranes and the chloroplast stroma. Transformants grown at 150 or 700 μmol quanta m−2 s−1 displayed wild-type phenotypes regardless of FNR content. Thylakoids isolated from plants with a 5-fold FNR increase over the wild type displayed only moderate stimulation (approximately 20%) in the rates of electron transport from water to NADP+. In contrast, when donors of photosystem I were used to drive NADP+ photoreduction, the activity was 3- to 4-fold higher than the wild-type controls. Plants expressing various levels of FNR (from 1- to 3.6-fold over the wild type) failed to show significant differences in CO2 assimilation rates when assayed over a range of light intensities and CO2 concentrations. Transgenic lines exhibited enhanced tolerance to photooxidative damage and redox-cycling herbicides that propagate reactive oxygen species. The results suggest that photosynthetic electron transport has several rate-limiting steps, with FNR catalyzing just one of them.
Proteome Dynamics during Plastid Differentiation in Rice
Authors: Kleffmann Torsten , von Zychlinski Anne , Russenberger Doris , Hirsch-Hoffmann Matthias , Gehrig Peter , Gruissem Wilhelm , Baginsky Sacha
Published: December 2006

We have analyzed proteome dynamics during light-induced development of rice (Oryza sativa) chloroplasts from etioplasts using quantitative two-dimensional gel electrophoresis and tandem mass spectrometry protein identification. In the dark, the etioplast allocates the main proportion of total protein mass to carbohydrate and amino acid metabolism and a surprisingly high number of proteins to the regulation and expression of plastid genes. Chaperones, proteins for photosynthetic energy metabolism, and enzymes of the tetrapyrrole pathway were identified among the most abundant etioplast proteins. The detection of 13 N-terminal acetylated peptides allowed us to map the exact localization of the transit peptide cleavage site, demonstrating good agreement with the prediction for most proteins. Based on the quantitative etioplast proteome map, we examined early light-induced changes during chloroplast development. The transition from heterotrophic metabolism to photosynthesis-supported autotrophic metabolism was already detectable 2 h after illumination and affected most essential metabolic modules. Enzymes in carbohydrate metabolism, photosynthesis, and gene expression were up-regulated, whereas enzymes in amino acid and fatty acid metabolism were significantly decreased in relative abundance. Enzymes involved in nucleotide metabolism, tetrapyrrole biosynthesis, and redox regulation remained unchanged. Phosphoprotein-specific staining at different time points during chloroplast development revealed light-induced phosphorylation of a nuclear-encoded plastid RNA-binding protein, consistent with changes in plastid RNA metabolism. Quantitative information about all identified proteins and their regulation by light is available in plprot, the plastid proteome database (http://www.plprot.ethz.ch).
Strategies for Functional Validation of Genes Involved in Reproductive Stages of Orchids
Authors: Lu Hsiang-Chia , Chen Hong-Hwa , Tsai Wen-Chieh , Chen Wen-Huei , Su Hong-Ji , Chang Doris Chi-Ning , Yeh Hsin-Hung
Published: December 2006

Plants in the largest family of angiosperms, Orchidaceae, are diverse in both specialized pollination and ecological strategies and provide a rich source for investigating evolutionary relationships and developmental biology. However, studies in orchids have been hindered by several challenges that include low transformation efficiency and long regeneration time. To overcome such obstacles, we selected a symptomless cymbidium mosaic virus (CymMV) isolate for constructing virus-induced gene-silencing vectors. The feasibility of the virus vectors was first assessed with use of an orchid phytoene desaturase gene. The vector was able to induce gene silencing in orchids; however, because of the slow growth of orchids, the commonly used phytoene desaturase gene was not a good visual marker in orchids. We inserted a 150-nucleotide unique region of a B-class MADS-box family gene, PeMADS6, into pCymMV-pro60. The transcription level of PeMADS6 in inoculated Phalaenopsis plants was reduced by up to 73%, but no effect was observed for other MADS-box family genes. In contrast, in Phalaenopsis plants inoculated with CymMV transcripts containing 500 nucleotides of PeMADS6, a conserved region among MADS-box genes, the transcription level of PeMADS6 and the B- and C-class MADS-box genes was reduced by up to 97.8% as compared with plants inoculated with the vector alone. Flower morphology was affected in the MADS-box family gene-silenced plants as well. This in vivo experiment demonstrates an efficient way to study genes involved in the reproductive stage of plants with a long life cycle.
A Family of MicroRNAs Present in Plants and Animals
Authors: Arteaga-Vázquez Mario , Caballero-Pérez Juan , Vielle-Calzada Jean-Philippe
Published: December 2006

Although many miRNAs are deeply conserved within each kingdom, none are known to be conserved between plants and animals. We identified Arabidopsis thaliana miR854 and miR855, two microRNAs (miRNAs) with multiple binding sites in the 3′ untranslated region (3′UTR) of OLIGOURIDYLATE binding PROTEIN1b (At UBP1b), forming miRNA:mRNA interactions similar to those that cause translational repression/mRNA cleavage in animals. At UBP1b encodes a member of a heterogeneous nuclear RNA binding protein (hnRNP) family. The 3′UTR of At UBP1b is sufficient to repress reporter protein expression in tissues expressing miR854 or miR855 (rosette leaves and flowers, respectively) but not where both miRNAs are absent (cauline leaves). Intergenic regions containing sequences closely resembling miR854 are predicted to fold into stable miRNA precursors in animals, and members of the miR854 family are expressed in Caenorhabditis elegans, Mus musculus, and Homo sapiens, all with imperfect binding sites in the 3′UTR of genes encoding the T cell Intracellular Antigen-Related protein, an hnRNP of the UBP1 family. Potential binding sites for miR854 are absent from UBP1-like genes in fungi lacking the miRNA biogenetic machinery. Our results indicate that plants and animals share miRNAs of the miR854 family, suggesting a common origin of these miRNAs as regulators of basal transcriptional mechanisms.
Identification of Important Regions for Ethylene Binding and Signaling in the Transmembrane Domain of the ETR1 Ethylene Receptor of Arabidopsis
Authors: Wang Wuyi , Esch Jeff J. , Shiu Shin-Han , Agula Hasi , Binder Brad M. , Chang Caren , Patterson Sara E. , Bleecker Anthony B.
Published: December 2006

The ethylene binding domain (EBD) of the Arabidopsis thaliana ETR1 receptor is modeled as three membrane-spanning helices. We surveyed ethylene binding activity in different kingdoms and performed a bioinformatic analysis of the EBD. Ethylene binding is confined to land plants, Chara, and a group of cyanobacteria but is largely absent in other organisms, consistent with our finding that EBD-like sequences are overrepresented among plant and cyanobacterial species. We made amino acid substitutions in 37 partially or completely conserved residues of the EBD and assayed their effects on ethylene binding and signaling. Mutations primarily in residues in Helices I and II midregions eliminated ethylene binding and conferred constitutive signaling, consistent with the inverse-agonist model of ethylene receptor signaling and indicating that these residues define the ethylene binding pocket. The largest class of mutations, clustered near the cytoplasmic ends of Helices I and III, gave normal ethylene binding activity yet still conferred constitutive signaling. Therefore, these residues may play a role in turning off the signal transmitter domain of the receptor. By contrast, only two mutations were loss of function with respect to signaling. These findings yield insight into the structure and function of the EBD and suggest a conserved role of the EBD as a negative regulator of the signal transmitter domain.
The SH3 domain of a M7 interacts with its C‐terminal proline‐rich region
Authors: Wang Qinghua , Deloia Matthew A. , Kang Yang , Litchke Casey , Zhang Naixia , Titus Margaret A. , Walters Kylie J.
Published: December 2006

Myosins play essential roles in migration, cytokinesis, endocytosis, and adhesion. They are composed of a large N‐terminal motor domain with ATPase and actin binding sites and C‐terminal neck and tail regions, whose functional roles and structural context in the protein are less well characterized. The tail regions of myosins I, IV, VII, XII, and XV each contain a putative SH3 domain that may be involved in protein–protein interactions. SH3 domains are reported to bind proline‐rich motifs, especially “PxxP” sequences, and such interactions serve regulatory functions. The activity of Src, PI3, and Itk kinases, for example, is regulated by intramolecular interactions between their SH3 domain and internal proline‐rich sequences. Here, we use NMR spectroscopy to reveal the structure of a protein construct from Dictyostelium myosin VII (DdM7) spanning A1620–T1706, which contains its SH3 domain and adjacent proline‐rich region. The SH3 domain forms the signature β‐barrel architecture found in other SH3 domains, with conserved tryptophan and tyrosine residues forming a hydrophobic pocket known to bind “PxxP” motifs. In addition, acidic residues in the RT or n–Src loops are available to interact with the basic anchoring residues that are typically found in ligands or proteins that bind SH3 domains. The DdM7 SH3 differs in the hydrophobicity of the second pocket formed by the 310 helix and following β‐strand, which contains polar rather than hydrophobic side chains. Most unusual, however, is that this domain binds its adjacent proline‐rich region at a surface remote from the region previously identified to bind “PxxP” motifs. The interaction may affect the orientation of the tail without sacrificing the availability of the canonical “PxxP”‐binding surface.
Is glycine a surrogate for a d‐amino acid in the collagen triple helix?
Authors: Horng Jia‐Cherng , Kotch Frank W. , Raines Ronald T.
Published: December 2006

Collagen is the most abundant protein in animals. Every third residue in a collagen strand is a glycine with φ, ψ = −70°, 175°. A recent computational study suggested that replacing these glycine residues with d‐alanine or d‐serine would stabilize the collagen triple helix. This hypothesis is of substantial importance, as the glycine residues in collagen constitute nearly 10% of the amino acid residues in humans. To test this hypothesis, we synthesized a series of collagen mimic peptides that contain one or more d‐alanine or d‐serine residues replacing the canonical glycine residues. Circular dichroism spectroscopy and thermal denaturation experiments indicated clearly that the substitution of glycine with d‐alanine or d‐serine greatly disfavors the formation of a triple helix. Host–guest studies also revealed that replacing a single glycine residue with d‐alanine is more destabilizing than is its replacement with l‐alanine, a substitution that results from a common mutation in patients with collagen‐related diseases. These data indicate that the glycine residues in collagen are not a surrogate for a d‐amino acid and support the notion that the main‐chain torsion angles of a glycine residue in the native structure (especially, φ > 0°) are critical determinants for its beneficial substitution with a d‐amino acid in a protein.
Self‐assembly of coiled‐coil tetramers in the 1.40 Å structure of a leucine‐zipper mutant
Authors: Deng Yiqun , Zheng Qi , Liu Jie , Cheng Chao‐Sheng , Kallenbach Neville R. , Lu Min
Published: December 2006

The hydrophobic core of the GCN4 leucine‐zipper dimerization domain is formed by a parallel helical association between nonpolar side chains at the a and d positions of the heptad repeat. Here we report a self‐assembling coiled‐coil array formed by the GCN4‐pAe peptide that differs from the wild‐type GCN4 leucine zipper by alanine substitutions at three charged e positions. GCN4‐pAe is incompletely folded in normal solution conditions yet self‐assembles into an antiparallel tetraplex in crystals by formation of unanticipated hydrophobic seams linking the last two heptads of two parallel double‐stranded coiled coils. The GCN4‐pAe tetramers in the lattice associate laterally through the identical interactions to those in the intramolecular dimer–dimer interface. The van der Waals packing interaction in the solid state controls extended supramolecular assembly of the protein, providing an unusual atomic scale view of a mesostructure.
Mixed osmolytes: The degree to which one osmolyte affects the protein stabilizing ability of another
Authors: Holthauzen Luis Marcelo F. , Bolen D. Wayne
Published: December 2006

Mixtures of organic osmolytes occur in cells of many organisms, raising the question of whether their actions on protein stability are independent or synergistic. To investigate this question it is desirable to develop a system that permits evaluation of the effect of one osmolyte on the efficacy of another to either force‐fold or denature a protein. A means of evaluating the efficacy of an osmolyte is provided by itsm‐value, an experimental quantity that measures the ability of the osmolyte to force a protein to unfold or fold. An experimental system is presented that enables evaluations of them‐values of osmolytes in the presence and absence of a second osmolyte. The experimental system involves use of a marginally stable protein in 10 mM buffer (pH 7, 200 mM salt, and 34°C) that is at the midpoint of its native to denatured transition. These conditions enable determination ofm‐values for protecting and denaturing osmolytes in the presence and absence of a second osmolyte, permitting assessment of the extent to which the two osmolytes affect each other's efficacy. The two osmolytes investigated in this work are the denaturing osmolyte, urea, and the protecting osmolyte, sarcosine. Results show unequivocally that neither osmolyte alters the efficacy of the other in forcing the protein to fold or unfold—the osmolytes act independently on the protein despite their combined concentrations being in the multi‐molar range. These osmolytes avoid altering one another's efficacy at these high concentrations because the number of osmolyte interaction sites on the protein is large and the binding constants are quite small. Consequently, the site occupancies are low enough in number that the two osmolytes neither compete nor cooperate in interacting with the protein.
Thermal Destruction of Streptococcus faecalis in Prepared Frozen Foods a
Authors: OTT THOMAS M. , EL‐BISI HAMED M. , ESSELEN WILLIAM B.
Published: December 2006

The thermal destruction rates of Streptococcus faecalis, ATCC 7080, were determined in a selected group of meat and fish precooked frozen products. Data on heat transfer through these products in a hot air household electric oven, were also obtained. Accordingly, the theoretical thermal treatments required to render such products commercially sterile were computed following the procedure of the General method of process calculation for canned foods with some modification. Inoculated product tests were also made to confirm the adequacy of the computed thermal treatments.

It is concluded that the procedure adopted for establishing the thermal treatment was accurate and proved feasible for this type of product. Based on the thermal resistance of our test strain, the heat treatments recommended on the commercial packages seem to be adequate, provided the heating and cooling procedures are similar to those followed in the present experiments. In the case of one product out of the five tested, however, the minimum recommended heating period fell short of the computed thermal requirement for that product.
Loss of Ascorbic Acid During Estimation by the Roe‐Kuether Method
Authors: TEWARI C. P. , KRISHNAN P. S.
Published: December 2006

Application of the 2,4‐dinitrophenylhydrazine method of Roe and co‐workers to plant extracts, wherein ascorbic acid was present largely or completely in the form of DHA and DKA, resulted in abnormal data, in the sense that the value of AA + DHA + DKA was significantly lower than that of DHA + DKA. Such a discrepancy, though not to the same degree, was observed also when the analyses were carried out on solutions of DHA. The loss is believed to take place during H2S treatment, there being a correlation between the extent of loss and the duration of H2S treatment, in the majority of the experiments.
Effect of Different Temperatures on Various Bacteria Isolated from Frozen Meat Piesa
Authors: KERELUK K. , PETERSON A. C. , GUNDERSON M. F.
Published: December 2006

The effect of temperature, particularly storage temperature, is one of the most important factors in controlling microbial populations of frozen foods. Adequate temperature control of frozen foods should limit the growth of microorganisms and insure maintenance of original quality and wholesomeness. This investigation was undertaken to show that correct storage temperature; do inhibit the growth of bacteria which might be considered as the source of potential public health hazard, while certain saprophytic species are able to survive and grow well at the same low temperatures. The cultures were all isolated from chicken pies.

Bacterial counts were determined by plating techniques on Brain Heart Infusion (BHI) agar after various time intervals up to 30 days at ‐13°, 0°, 5°, 10°, 20° and 37° C, using both BHI broth and chicken gravy as media. Very similar results were obtained in the two media.

Escherichia coli and Streptococcus faecalis had a minimum growth temperature between 5° and 10° C for active reproduction. A minimum growth temperature between 5° and 10° C was observed for the culture of Staphylococcus aureus. Of two cultures representing variants of Pseudomonas fluorescens, one culture followed the growth‐temperature pattern shown by the previously mentioned organisms and failed to grow at or below 5° C. The other P. fluorescens culture grew rapidly at 5° C. Ability to grow at low temperatures is a constitutive characteristic of the organism and is not common to all types of bacteria. At refrigerator temperatures, the growth of the psychrophilic saprophytic species tested completely outstripped the growth of several bacteria of public health significance. This indicates the great likelihood that a frozen food on defrosting, particularly in a refrigerator, would become completely unacceptable, due to the development of off flavors and odors and deteriorated physical appearance before it became a health hazard.
Rheology of Cocoa Butter. IV. Further Studies of “Omega” Crystallinity
Authors: STERLING CLARENCE
Published: December 2006

An X‐ray diffraction study was made of several plastic fats, including lard, butterfat, oleomargarine, and hydrogenated vegetable shortenings. Their liquid contents were varied by altering the holding temperature. Separate mixtures were made of cocoa butter or tristearin with corn oil, tributyrin, or trioctanoin, and their diffraction patterns were obtained. The crystal form (omega), previously described for oxidized cocoa butter, was found in the first group of fats and in the corn oil‐tristearin mixture. Omega crystallinity was not related to the solid‐liquid ratio of the fats or to differences in molecular length in the constituent fatty acid radicals. Omega crystallinity seemed to be related to a general difficulty in crystallization, probably due to steric hindrances.
The Chemical Composition of Beef Protein Fractions Before and After Irradiationa
Authors: HEDIN P. A. , KURTZ GEORGE W. , KOCH ROBERT B.
Published: December 2006

A protein from beef prepared by ammonium sulfate fractionation of a hot‐water extract, gave a “wet dog” odor when irradiated. This protein has an amino acid constitution similar to that of gelatin, is associated with a nitrogen‐containing polysaccharide, and exhibits the solubility properties of a glucoprotein. When irradiated, 15% of the nitrogen becomes dialyzable and 13% of the amino acids are destroyed. The sulfhydryl content decreases markedly, whereas the ammonia, as determined after acid hydrolysis, and the ultraviolet absorption increase. Similar radiation‐induced changes can be observed with proteins that do not produce an odor. Consequently, the odor discussed in this report does not appear to be produced from simple amino acids per se.
Pectic Substances of Valencia Oranges at Different Stages of Maturitya
Authors: SINCLAIR WALTON B. , JOLLIFFE VIRGIL A.
Published: December 2006

Seasonal changes in concentrations of pectic substances of the peel and pulp were followed by determining the total‐ and water‐soluble pectic substances as an‐hydrogalacturonic acid during growth and development under normal conditions. With the rapid development of fruit growth in the early part of the season, a tremendous initial increase occurred in the total‐ and water‐soluble pectic materials followed‘by a gradual decrease through the remainder of the season. The percentage methylation of the pectic substances of Valencia orange peel rises rapidly to approximately an 80 per cent level and remains relatively constant during the rest of the season.
Carbonyls in Qxidizing Fat. IV. The Role of Various Fatty Acid Components in Carbonyl Generation
Authors: ELLIS REX , GADDIS A. M. , CURRIE GEORGE T.
Published: December 2006

Volatile monocarbonyls produced by mildly oxidized esters of oleic, linoleic, linolenic acids and fats have been characterized by paper chromatography of 2,4‐dinitrophenylhydrazone derivatives. The unsaturated fatty acid esters yielded a total of 7 n‐alkanals, 8 n‐alk‐2‐enals, and 4 alk‐2,4‐dienals; and similar results were obtained with the fats. Each unsaturated acid produced three major characteristic aldehydes. Comparisons of esters and glycerides showed the presence of keto or aldehyde ester scission products.
The Effect of Methylation Upon the Antioxidant and Chelation Capacity of Quercetin and Dihydroquercetin in a Lard Substratea, b, c
Authors: CRAWFORD DAVID L. , SINNHUBER RUSSELL O. , AFT HARVEY
Published: December 2006

The relative importance of the hydroxyl group positions of quercetin and the metal‐complexing sites of the molecule to antioxidant capacity in lard was investigated. The antioxidant action of quercetin seems to be a combination of reaction with free radicals and metal‐ion complexing; with the former being the more important. Selective methylation of the hydroxyl groups of the quercetin molecule generally decreased the antioxidant activity. Ultraviolet absorption spectra of quercetin and copper‐quercetin complexes suggest that quercetin will complex two moles of copper ion by intramolecular complexing and a third by intermolecular complexing. Copper‐quercetin complexes retain some antioxidant ability although it is much less than that of uncomplexed quercetin.
The Carbohydrates in the Peel of Oranges and Grapefruita
Authors: TING S. V. , DESZYCK E. J.
Published: December 2006

The carbohydrates of the citrus peel were divided according to their solubility in 80% ethanol. The alcohol‐soluble solids were composed of about 80% total sugars. Free xylose was found in trace amounts. Glucose, fructose, and sucrose were the main sugars present. Sucrose content of the peel was in general lower than the total reducing sugars. The alcohol‐insoluble solids were separated into “pectic substance,”“hemicellulose,” and “cellulose” fractions by extracting with different solvents. The “pectic substance” fraction upon hydrolysis yielded arabinose, galactose, and galacturonic acid. “Hemicellulose” fraction contained xylose, arabinose, galactose, glucose, and some uronic acids in its hydrolysate. In the “cellulose” fraction, glucose was dominant with some xylose and arabinose being also present. Traces of galactose and some uronic acids and in some cases mannose were found. On the average only between 53 and 70 per cent of the alcohol‐insoluble solids were recovered as carbohydrates in the peel of various citrus varieties.
Autoxidation of Fish Oils. I. Identification of Volatile Monocarbonyl Compounds from Autoxidized Salmon Oila, b, c
Authors: YU T. C. , DAY EDGAR A. , SINNHUBER RUSSELL O.
Published: December 2006

Isolation and identification of a number of volatile monocarbonyls from autoxidized salmon oil were accomplished. The carbonyls, volatile by vacuum steam distillation, were reacted with 2,4‐dinitrophenylhydrazine. The 2,4‐dinitrophenyl‐hydrazones were separated by partition and paper chromatograpy. Spectrophotometric analyses and melting‐point determinations were made. The data show that, in addition to malonaldehyde previously reported, positive identification was made on 15 monocarbonyls: the C2, C3, C5, C6, C7, C8, and C9 alkanals; the C3, C4, C5, C6, C8, C9, and C10 2‐enals; and hept‐2,4‐dienal. Tentative identification of butanal, dec‐2,4‐dienal, and undec‐2‐enal was based upon a comparison of chro‐matographic behavior and absorption spectra of the authentic with the unknown. The isolated ketones, tentatively identified as 2‐hexanone, 2‐octanone, 2‐nonanone, and 2‐decanone, were characterized by the preceding methods and by their behavior in alcoholic potassium hydroxide. Five additional compounds of unknown identity were isolated; three provided sufficient material for melting‐point determinations. Including the forerun, at least 28 carbonyls were found in the volatile portion of rancid salmon oil.
Oxidation of Fat in Model Systems Related to Dehydrated Foods.a II. Composition and Position of Dispersed Lipid Components and Their Effect on Oxidation Rates
Authors: BISHOV S. J. , HENICK A. S. , KOCH ROBERT B.
Published: December 2006

Oxidation rates at elevated temperatures of model dehydrated systems containing dispersed lipids are influenced by concentration of the components, type of dispersing medium, and position of the lipid film with respect to the dispersing medium. Generally, the proteins decreased, and polymeric carbohydrates accelerated, oxidation rates. Arginine and lysine salts of safflower fatty acids were extremely stable. Phospholipids had a stabilizing influence when dispersed with the fat and the dispersing medium prior to freeze‐drying or when applied as a film between the dry medium and the fat film. When the positions of the fat and the phospholipid films were reversed, the protective action of the phospholipids on the stability of the system decreased markedly.
Survival of Bacillus stearothermophilus Spores as a Means of Measuring Effective Electron‐Beam Dosagea,b
Authors: POSTWEILER JUNE E. , CALDWELL ELWOOD F.
Published: December 2006

Because of the limited penetrating ability of low‐voltage electrons, depth and density are necessarily major considerations in the experimental irradiation of food by this means. In this study, survival of bacteria dispersed in agar was used to indicate the effective amounts of irradiation resulting at various depths from various electron doses to the surface. The per cent survival at each depth was plotted against the dose received as measured by cobalt glass dosimeters located at the same depth. These had been calibrated in terms of dose response by means of gamma radiation delivered by a source accurately calibrated by ferrous dosimetry. Within the 3‐cm depth studied, a linear relationship was found between dose and log per cent survival.
Variations in Proximate Composition of North Carolina Scallop Meats
Authors: WEBB N. B. , THOMAS F. B. , BUSTA F. F. , MONROE R. J.
Published: December 2006

SUMMARY: Bay scallops (Aequipecten irradians), calico scallops (Aequipecten gibbus) and sea scallops (Placopecten magellanicus) were sampled from known locations and months of harvest for determination of proximate composition. A scallop sample (Chlamys hericius) was obtained from near Whidbey Island, Puget Sound, for comparative purposes. The adductor muscles were analyzed for total moisture, protein, fat, glycogen and ash content. The proximate composition varied widely among locations and months of harvesting. In general, coefficients of variation were relatively low for moisture and protein but high for fat, glycogen and ash. The range for each component was fairly similar among species studied. The percent ranges for bay and calico scallop meats, respectively, were: moisture 74.15–83.66, 76.12–81.86; protein 13.44–21.57, 13.28–17.53; fat 0.23–0.91, 0.23–1.13; glycogen 0.13–3.86, 0.35–3.71 and ash 1.09–2.24, 1.17–1.91. Sea scallop percent ranges were: moisture 74.63–80.97; protein 13.87–18.11; fat 0.31–0.96; glycogen 0.27–8.74 and ash 1.28–1.81.
A Simplified and Rapid Method to Uniformly Size Rib Steak Pieces for Taste Panel Evaluation
Authors: BEERY K. E. , ZIEGLER J. H.
Published: December 2006

SUMMARY: Uniformity of size and preparation of steak samples are important prerequisites for accurate taste panel analysis. A system is described to utilize a Broiling and Sectioning Apparatus (BSA) to obtain this uniformity. Frozen beef rib steaks are uniformly sized before broiling and then sectioned into bite‐size pieces for presentation to a taste panel.
Lipid in Ripening Banana Fruit
Authors: GOLDSTEIN JUDITH L. , WICK EMILY L.
Published: December 2006

SUMMARY: Lipid extracts were isolated from unripe and ripe banana pulp and peel and the fatty acid composition of the extracts was determined. Unsaturated acids, particularly linoleic and palmitoleic, decreased about 3‐fold in the pulp while more than a 2‐fold increase in stearic acid occurred. In general, unsaturated fatty acids decreased in both the pulp and peel during ripening. The peel contained almost 4 times more lipid than the pulp.
Photoinduced Reduction of Nootkatone
Authors: STEVENS K. L.
Published: December 2006

SUMMARY: Photolysis of the principal flavoring constituent of grapefruit, nootkatone, in methanol gave rise to a number of compounds. One of them has been isolated and shown to be 1,10‐dihydronootkatone.
Palatability and Selected Related Characteristics of Three Types of Roasted Porcine Muscle
Authors: SEARCY D. JEAN , HARRISON DOROTHY L. , ANDERSON LOIS L.
Published: December 2006

SUMMARY: A completely randomized design was followed to evaluate 48 roasts posterior third of the loin) from 12 Duroc and 12 Poland China barrows. Antemortem treatment of pigs produced “normal”, pale‐soft‐exudative (PSE) and dark‐firm‐dry (DFD) longissimus dorsi (LD) muscle. Meat was roasted at 350°F to an internal temperature of 167°F and evaluated by organoleptic and selected objective measurements. There was no significant organoleptic preference for one type (“normal”, PSE, DFD) of LD. Also, differences among types of muscle were not significant for roasting time, volume of press fluid or total moisture (press method); whereas roasting losses, total moisture (Brabender) and pH of LD were affected significantly by type of muscle. In general, there were significant (P < 0.05) differences between PSE and DFD muscle, and between “normal” and DFD muscle. DFD muscle exhibited the smallest roasting loss and greatest total moisture, whereas PSE muscle had the greatest roasting loss and least total moisture. DFD muscle rated highest in pH and lowest in Warner‐Bratzler shear value. LD from Durocs was more tender (P < 0.05), had a higher (P < 0.05) pH, and contained less (P < 0.01) total moisture (Brabender) than LD from Poland Chinas. Cooking losses were greater (P < 0.05) for roasts from Durocs than for roasts from Poland Chinas.
Identification and Quantitative Analysis of Phospholipids in Cocoa Beans
Authors: PARSONS J. G. , KEENEY P. G. , PATTON S.
Published: December 2006

SUMMARY: The lipids extracted from several common cocoa bean varieties were separated into neutral lipid, glycolipid, and phospholipid fractions. The composition of the total lipid extract was 98% neutral lipid and 1 to 2% oolar lioid of which aporoximatelv 70% was glycolipid and 30% was phospholipids. Two‐dimensional thin‐layer chromatography was used to separate all of the known major phospholipids. The relative distribution of the phospholipids was determined by quantitative phosphorus analyses of individual spots scraped from two‐dimensional thin‐layer plates. The major components were lysophosphatidyl choline, phosphatidyl choline, phosphatidyl ethanolamine, and phosphatidyl inositol. Phosphatidyl choline was found to contribute 36 to 40% of the phospholipids of cocoa beans. The phospholipid composition of Accra, Arriba, and Bahia beans was shown to be quite similar although minor variations were observed.
Aldehydes, Ketones and Esters in Valencia Orange Peel Oil
Authors: MOSHONAS M. G. , LUND ERIC D.
Published: December 2006

SUMMARY: The aldehydes, ketones and esters in the volatile portion of Valencia orange oil have been isolated and identified. Seventeen aldehydes and ketones and three esters are included, 10 of which have never been identified as constituents of Valencia oil. Cis‐ and trans‐limonene oxide have also been found to occur in the same fraction. This is the first time that these compounds have been identified in cold‐pressed orange oil. A series of five homologous α,β‐unsaturated aldehydes were isolated and partially characterized.
Epimysial Connective Tissue Scores as Related to Beef Tenderness
Authors: FIELD R. A. , RILEY M. L. , CHANG YET‐OY
Published: December 2006

SUMMARY: Steaks from 24 bulls 20 months old, 89 bulls 14 months old and 109 steers 20 months old were used to relate thickness of epimysial tissue to the amount of intra‐muscular connective tissue, and to correlate these factors with Warner‐Bratzler shear values in muscles cooked to 140 or 160°F. The thickest portion of the LD epimysium was greater in lighter weight bulls than it was in heavier steers. Epimysial extension and thickness varied according to muscle location but at the same location it was not significantly different in steaks from tough versus tender steers. Differences in hydroxyproline content and connective tissue of steers and young bulls were small but older bulls had slightly greater amounts of both. The LD epimysium was tougher in older bulls than in younger bulls.

Shear values of epimysial tissue varied considerably within animals of the same age, especially when roasted to 140°F. Most connective tissue differences due to line of cattle were small. Correlations within groups of cattle between thickness of epimysial tissues of different muscles or between epimysial thickness and intramuscular connective tissues were low. With few exceptions neither hydroxyproline, epimysial thickness nor connective tissue scores were significantly related to shear force of muscle or shear force of epimysial tissue itself. Correlations between shear force of the LD and BF muscles were not significant (P < 0.05) in animals of the same age. There was a tenderness interaction between age of animal and type of muscle which suggested that collagen gelatinization occurred at a faster rate in the LD than in the BF as age increased.
Polygalacturonase Content of Dates and Its Relation to Maturity and Softness
Authors: HASEGAWA S. , MAIER V. P. , KASZYCKI H. P. , CRAWFORD J. K.
Published: December 2006

SUMMARY: The changes in polygalacturonase (PG) activity during ripening and the relationship between its activity and the quality of Deglet Noor dates were studied. PG activity, which was virtually absent at the green stage, began to develop as maturity progressed. The greatest part of the development occurred at the late red stage and activity reached its maximum when the fruits commenced softening. Among the four grades of dates used in this study the activity was highest with natural, followed by waxy, number 1 dry and number 2 dry grades. The dates contained 0.9‐1.3 units of PG per g of fresh tissue. The results of chemical and physical analyses related to the texture are also reported.
Relationship between Meat Swelling, Viscosity, Extract‐release Volume, and Water‐holding Capacity in Evaluating Beef Microbiol Quality
Authors: SHELEF LEORA A. , JAY JAMES M.
Published: December 2006

SUMMARY: This research was undertaken in order to determine the relationship between the phenomena of meat swelling (SW), viscosity (η), extract‐release volume (ERV), and wafer‐holding capacity (WHC) as simple and rapid techniques of determining beef microbiol qualify. These techniques were compared by analyzing beef samples held from freshness to spoilage at refrigerator temperatures, fresh beef homogenized with urea, and beef adjusted to different pH values. In addition, irradiated fresh ground beef samples were inoculated with the normal flora of spoiled beef and analyzed similarly.

With the microbially spoiled meats the highest degree of correlation occurred between SW and ERV, followed by ERV & WHC, SW & η, η & ERV and SW & WHC. These findings indicate that ERV and SW are quite similar and equally reliable in determining meat microbiol qualify while the relationships between η and ERV, and η & WHC were of lower orders of significance.

When fresh beef was homogenized with urea at levels between 0.5 and 5M, η correlated best with SW followed by ERV & η, and ERV & SW. Over the pH range 3‐11, SW and ERV correlated best followed rather closely by SW and η, and ERV & η.
Autoxidation of Methyl Linoleate in Freeze‐Dried Model Systems. 4. Effects of Metals and of Histidine in the Absence of Water
Authors: TJHIO K. H. , KAREL M.
Published: December 2006

SUMMARY: Autoxidation of methyl linoleate dispersed on filter paper was studied in the dry state in the presence and absence of additives. Oxidation was followed volumetrically and by measuring the increase in conjugated dienes. Evaluation of the rate data indicates that added histidine is antioxidant in the very early stages of the oxidation and becomes prooxidant in the later stages. Increasing the concentration of histidine promoted an earlier appearance of its prooxidant effect. Cobalt chloride and manganese sulfate had a pronounced catalytic effect on the oxidation reaction in the model systems buffered to a high (8.0 and 9.0) but not to a low (4.0) pH. Histidine increased the catalytic activity of manganese but eliminated that of cobalt. Thin‐layer chromatography showed that conditions under which histidine increased the prooxidant effect of manganese also resulted in the appearance of some decomposition products of histidine. These decomposition products may have catalytic activity.
Composition of Montmorency Cherry Essence. 2. High‐boiling Components
Authors: STINSON E. E. , DOOLEY C. J. , FILIPIC V. J. , HILLS C. H.
Published: December 2006

SUMMARY: Volatile components of commercial Montmorency cherry essence boiling above ethanol were extracted from the essence by ether and concentrated by distillation. This concentrate was fractionated by gas chromatography. Individual components were identified using the methods of functional group analysis, gas co‐chromatography, infrared analysis and mass spectrometry. The concentrations of the components in the original essence were estimated. The major components identified were n‐propyl alcohol, isobutyl alcohol, isoamyl alcohol, and benzaldehyde. Minor components identified include n‐butanol, n‐hexanol, a hexenol, benzyl alcohol, α‐terpineol, furfural, isoprene, myrcene and numerous higher terpenes, methyl benzoate, ethyl benzoate, benzyl acetate, ethyl caprylate, ethyl caprate, n‐propyl benzoate, isobutyl benzoate, isoamyl benzoate and di‐butyl phthalate.
Water Extractable Proteins of Porcine Muscle
Authors: KOLCZAK T. , WEBER MIROSLAWA
Published: December 2006

SUMMARY: The study was performed on 31 samples of porcine muscle (m. longissimus dorsi) of different qualities, ranging from extremely pale, soft and exudative (PSE) to dark red in color, firm in structure and dry in appearance (DFD) in order to determine the water solubility of muscle proteins 24 hr post mortem. It was found that the water solubility of muscle proteins depends on the quality of the muscle, and is lowest in extremely PSE muscle. It was demonstrated, with the aid of electrophoresis on agar and acrylamide gels, that some sarcoplasmic proteins which undergo precipitation 30 min after adding a citrate‐phosphate buffer (pH 4.6) at temperature of 20°C are extracted in smaller amounts from PSE muscle than from normal muscle. One of these fractions was benzidine positive.
Studies on Some Physical Properties of Bovine Skeletal Muscle
Authors: KLINE R. C. , SINK J. D. , BEERY K. E. , ZIEGLER J. H. , WILSON L. L.
Published: December 2006

SUMMARY: The physical properties of the major muscles of the round from 30 crossbred beef and 20 straightbred dairy carcasses were studied. Sex, sire and body type were related to these properties. Generally, the steers had longer, heavier and lighter‐colored muscles than the heifers. A negative relationship was noted between the specific gravity and reflectance values for the crossbred muscles. The semimembranosus muscle was heaviest and accounted for the highest percent of the rough round in certain beef and dairy sire groups. In the dairy cattle, the weight of the biceps femoris muscle was also affected by sire. Heritability estimates indicated that the weight of the semimembranosus was highly heritable and its percent of the rough round moderately heritable in both beef and dairy cattle. The dairy b. femoris weight and circumference were also moderately heritable. Color reflectance, specific gravity, pH, length and circumference/length ratio were not observed to be heritable physical properties.