bluuebunny/crossref_metadata_2025 huggingface dataset:
Approaches for optimizing the calibration standard of Tewameter TM 300
Authors: Miteva Maria , Richter Stefan , Elsner Peter , Fluhr Joachim W.
Published: August 2006

Abstract: Calibration of devices measuring transepidermal water loss (TEWL) is in intensive discussion. Comparative studies revealed that comparable measuring systems, e.g. open and closed chamber systems, do not always deliver the same results, even when expressing the measured values in SI units, namely in g/m2/h. Therefore, adequate and reliable calibration procedures need to be established. We were able to test the reliability of a multi‐step calibration algorithm for an open chamber system such as Tewameter TM 300. In order to achieve reliable measurements, the maintenance of stable microclimate conditions without air turbulences is mandatory. The TEWL values should be compared with those determined gravimetrically on heated skin simulators. The reproducibility of the results is warranted by consecutive measurements on different adjacent spots of a defined area. Preheating of the probe sensors is an effective approach for shortening the measuring time and gaining a rapid steady‐state. The accurate calibration of the probe can be checked under laboratory conditions any time. The critical point of the calibration and ultimately the accuracy of in vivo measurements maintain the steady functional capacity of the probes during the entire duration of continuous studies. The studied calibration procedure ensures these requirements.
Effects of Biologically Active Tumour‐Promoting and Non‐Promoting Phorbol Esters on In Vitro Growth of Melanocytic Cells
Authors: BROOKS GAVIN , BIRCH MARY , HART IAN R.
Published: August 2006

Sapintoxin A (SAP A), a naturally occurring biologically active but non‐promoting phorbol ester, acts as an effective in vitro mitogen for freshly derived human melanocytes. Seven days after addition of 50 nM SAP A there was a four to fivefold increase in melanocyte number over that observed in untreated control cultures comparable to that achieved with a 50 nM concentration of 12‐0‐tetradecanoylphorbol 13‐acetate (TPA). The fluorescent stage 2 promoter sapintoxin D (SAP D) also supported the growth of these cells, with a 50 nM dose producing an increase in cell number comparable to that observed with 200 nM TPA. Similar results were obtained with an established, but non‐tumorigenic, line of murine melanocytes. The same compounds exerted a potent anti‐proliferative effect against transformed melanocyte lines of murine and human origin associated with morphological alterations and an increase in melanin production consistent with induced cytodifferentiation.
Studies on Cellular Adhesion of Xenopus laevis Melanophores: Pigment Pattern Formation and Alteration In Vivo by Endogenous Galactoside‐Binding Lectin or its Sugar Hapten Inhibitor
Authors: FRUNCHAK YVETTE N. , MILOS NADINE C.
Published: August 2006

We have studied the development of Xenopus laevis tail melanophores and the effects on these cells on confrontation with endogenous X. laevis galactoside‐binding lectin or its sugar hapten inhibitor thiodigalactoside (TDG). An initial population of unpigmented cells differentiates into melanophores on the dorsal surface of the neural tube, and on the dorsal and ventral apices of the myotomes, forming the larval pattern. Melanophores secondarily populate the flank, forming a spaced arrangement which is later transformed into a dorsal and ventral stripe. A technique has been developed for confrontation of premigratory neural crest with purified lectin or TDG. These molecules impact on tail melanophores. With lectin treatment melanophore numbers decrease, and cell morphologies and arrangements change. TDG treatment, however, primarily affects pigment cell morphology. These results suggest that both galactoside‐bearing receptors for this lectin and the lectin itself can affect melanophores in this species of frog.
Lipid Peroxidation in Pigmented and Unpigmented Liver Tissues: Protective Role of Melanin
Authors: SCALIA MARINA , GEREMIA ERNESTO , CORSARO CONCETTA , SANTORO CARMEN , BARATTA DANIELA , SICHEL GIOVANNI
Published: August 2006

The protective role of melanin as an antioxidant biopolymer against lipid peroxidation was investigated. In pigmented frog liver and in albino rat liver the following were tested: thiobarbituric acid (TBA) reactive material (to show the induced lipoperoxidation in vitro), fatty acids, and reduced glutathione content. Our results show that susceptibility to the in vitro lipoperoxidation induced by ferrous ions is lower in the tissue containing melanin, though the content of the polyunsaturated fatty acids is higher in pigmented than in unpigmented tissues and reduced glutathione levels are lower in pigmented tissue. Our data support the hypothesis that melanin could reduce lipoperoxidation in pigmented tissue.
Foetal Human Melanocytes: In Situ Detection, In Vitro Culture and Differentiation Characteristics at 6–11 Weeks EGA
Authors: POOLE I. CAROLINE LE , WIJNGAARD RENÉ M.J.G.J. VAN DEN , VERKRUISEN RONALD P. , LAMERS WOUT H. , TROOST DIRK , WESTERHOF WIETE , DAS PRANAB K.
Published: August 2006

In vivo, melanocytes were detected in epidermis from human tissue of 6.5 weeks estimated gestinational age (EGA) and older. We have successfully established melanocyte monocultures from tissue of 9 to 10 weeks EGA. To our knowledge, this is the first report on physiology of human foetal melanocytes in monoculture. In culture, such melanocytes retained foetal characteristics. Proliferation rates noted were markedly higher (approximately 2.7‐fold) when compared to those in cultures of neonatal melanocytes. Moreover, when analyzing cellular phenotypes by markers for cells of the melanocytic lineage, foetal cells isolated from tissue of 9 weeks EGA reproducibly showed expression of the high molecular weight (HMW) antigen and c‐kit to an extent intermediate to that found in neonatal melanocytes and M14 melanoma cells. Such differential expression was not observed if cells were isolated from tissue of 10 weeks EGA, indicating that the foetal environment provides essential differentiation stimuli during the 10th week of gestation. Moreover, these results are supportive of the theory that malignant transformation involves a process of dedifferentiation. In all, human foetal melanocyte culture provides a useful model to investigate pigment cell differentiation.
Therapeutic treatments potentially mediated by melatonin receptors: potential clinical uses in the prevention of osteoporosis, cancer and as an adjuvant therapy
Authors: Witt‐Enderby Paula A. , Radio Nicholas M. , Doctor John S. , Davis Vicki L.
Published: August 2006

Abstract:  Melatonin's therapeutic potential is grossly underestimated because its functional roles are diverse and its mechanism(s) of action are complex and varied. Melatonin produces cellular effects via a variety of mechanisms in a receptor independent and dependent manner. In addition, melatonin is a chronobiotic agent secreted from the pineal gland during the hours of darkness. This diurnal release of melatonin impacts the sensitivity of melatonin receptors throughout a 24‐hr period. This changing sensitivity probably contributes to the narrow therapeutic window for use of melatonin in treating sleep disorders, that is, at the light‐to‐dark (dusk) or dark‐to‐light (dawn) transition states. In addition to the cyclic changes in melatonin receptors, many genes cycle over the 24‐hr period, independent or dependent upon the light/dark cycle. Interestingly, many of these genes support a role for melatonin in modulating metabolic and cardiovascular physiology as well as bone metabolism and immune function and detoxification of chemical agents and cancer reduction. Melatonin also enhances the actions of a variety of drugs or hormones; however, the role of melatonin receptors in modulating these processes is not known. The goal of this review is to summarize the evidence related to the utility of melatonin as a therapeutic agent by focusing on its other potential uses besides sleep disorders. In particular, its use in cancer prevention, osteoporosis and, as an adjuvant to other therapies are discussed. Also, the role that melatonin and, particularly, its receptors play in these processes are highlighted.
Identification and Characterization of Associated with Lipid Droplet Protein 1: A Novel Membrane‐Associated Protein That Resides on Hepatic Lipid Droplets
Authors: Turró Silvia , Ingelmo‐Torres Mercedes , Estanyol Josep M. , Tebar Francesc , Fernández Manuel A. , Albor Cecilia V. , Gaus Katharina , Grewal Thomas , Enrich Carlos , Pol Albert
Published: August 2006

Alcoholic and nonalcoholic liver steatosis and steatohepatitis are characterized by the massive accumulation of lipid droplets (LDs) in the cytosol of hepatocytes. Although LDs are ubiquitous and dynamic organelles found in the cells of a wide range of organisms, little is known about the mechanisms and sites of LD biogenesis. To examine the participation of these organelles in the pathophysiological disorders of steatotic livers, we used a combination of mass spectrometry (matrix‐assisted laser desorption ionization‐time of flight and LC‐MS electrospray) and Western blot analysis to study the composition of LDs purified from rat liver after a partial hepatectomy. Fifty proteins were identified. Adipose differentiation‐related protein was the most abundant, but other proteins such as calreticulin, TIP47, Sar1, Rab GTPases, Rho and actin were also found. In addition, we identified protein associated with lipid droplets I [ALDI (tentatively named Associated with LD protein 1), a novel protein widely expressed in liver and kidney corresponding to the product of 0610006F02Rik (GI:27229118). Our results show that, upon lipid loading of the cells, ALDI translocates from the endoplasmic reticulum into nascent LDs and indicate that ALDI may be targeted to the initial lipid deposits that eventually form these droplets. Moreover, we used ALDI expression studies to view other processes related to these droplets, such as LD biogenesis, and to analyze LD dynamics. In conclusion, here we report the composition of hepatic LDs and describe a novel bona fide LD‐associated protein that may provide new insights into the mechanisms and sites of LD biogenesis.
Fast and Precise Protein Tracking Using Repeated Reversible Photoactivation
Authors: Chudakov Dmitriy M. , Chepurnykh Tatyana V. , Belousov Vsevolod V. , Lukyanov Sergey , Lukyanov Konstantin A.
Published: August 2006

Photoactivatable fluorescent proteins opened principally novel possibilities to study proteins’ movement pathways. In particular, reversibly photoactivatable proteins enable multiple tracking experiments in a long‐drawn work with a single cell. Here we report ‘protein rivers tracking’ technique based on repeated identical rounds of photoactivation and subsequent images averaging, which results in dramatic increase of imaging resolution for fast protein movement events.
Biochemical characterization of MelJ and MelK
Authors: Müller I. , Müller R.
Published: August 2006

Melithiazol and myxothiazol are two myxobacterial metabolites that are highly efficient electron transport inhibitors of the respiratory chain. MelJ and MelK encoded in the melithiazol biosynthetic gene cluster were recently shown to be involved in the formation of the methyl ester from a hypothetical amide intermediate. In vivo studies suggest that the structurally highly similar amide myxothiazol A can be used as a substrate mimic of the hypothetical melithiazol amide to characterize the hydrolase MelJ. Both enzymes were produced in Escherichia coli as intein chitin fusion proteins and were purified using affinity chromatography. MelJ was found to catalyse the conversion of the amide myxothiazol to free myxothiazol acid. The formerly unknown myxothiazol acid was purified and used as a substrate for the methyl transferase MelK which methylates the compound using S‐adenosyl‐methionine as cosubstrate. Sequence analyses suggest that MelJ and MelK are members of the amidase signature family and of a new subclass of methyltransferases, respectively. Kinetic analyses point at a very high substrate specificity for both enzymes. Furthermore, the in vitro reconstitution of a unique mechanism of methyl ester formation found in myxobacteria is reported.
The CssRS two‐component regulatory system controls a general secretion stress response in Bacillus subtilis
Authors: Westers Helga , Westers Lidia , Darmon Elise , van Dijl Jan Maarten , Quax Wim J. , Zanen Geeske
Published: August 2006

Bacillus species are valuable producers of industrial enzymes and biopharmaceuticals, because they can secrete large quantities of high‐quality proteins directly into the growth medium. This requires the concerted action of quality control factors, such as folding catalysts and ‘cleaning proteases’. The expression of two important cleaning proteases, HtrA and HtrB, of Bacillus subtilis is controlled by the CssRS two‐component regulatory system. The induced CssRS‐dependent expression of htrA and htrB has been defined as a protein secretion stress response, because it can be triggered by high‐level production of secreted α‐amylases. It was not known whether translocation of these α‐amylases across the membrane is required to trigger a secretion stress response or whether other secretory proteins can also activate this response. These studies show for the first time that the CssRS‐dependent response is a general secretion stress response which can be triggered by both homologous and heterologous secretory proteins. As demonstrated by high‐level production of a nontranslocated variant of the α‐amylase, AmyQ, membrane translocation of secretory proteins is required to elicit this general protein secretion stress response. Studies with two other secretory reporter proteins, lipase A of B. subtilis and human interleukin‐3, show that the intensity of the protein secretion stress response only partly reflects the production levels of the respective proteins. Importantly, degradation of human interleukin‐3 by extracellular proteases has a major impact on the production level, but only a minor effect on the intensity of the secretion stress response.
Iron regulatory protein‐independent regulation of ferritin synthesis by nitrogen monoxide
Authors: Mikhael Marc , Kim Sangwon F. , Schranzhofer Matthias , Lin Shan S. , Sheftel Alex D. , Mullner Ernst W. , Ponka Prem
Published: August 2006

The discovery of iron‐responsive elements (IREs), along with the identification of iron regulatory proteins (IRP1, IRP2), has provided a molecular basis for our current understanding of the remarkable post‐transcriptional regulation of intracellular iron homeostasis. In iron‐depleted conditions, IRPs bind to IREs present in the 5′‐UTR of ferritin mRNA and the 3′‐UTR of transferrin receptor (TfR) mRNA. Such binding blocks the translation of ferritin, the iron storage protein, and stabilizes TfR mRNA, whereas the opposite scenario develops when iron in the intracellular transit pool is plentiful. Nitrogen monoxide (commonly designated nitric oxide; NO), a gaseous molecule involved in numerous functions, is known to affect cellular iron metabolism via the IRP/IRE system. We previously demonstrated that the oxidized form of NO, NO+, causes IRP2 degradation that is associated with an increase in ferritin synthesis [Kim, S & Ponka, P (2002) Proc Natl Acad Sci USA99, 12214–12219]. Here we report that sodium nitroprusside (SNP), an NO+ donor, causes a dramatic and rapid increase in ferritin synthesis that initially occurs without changes in the RNA‐binding activities of IRPs. Moreover, we demonstrate that the translational efficiency of ferritin mRNA is significantly higher in cells treated with SNP compared with those incubated with ferric ammonium citrate, an iron donor. Importantly, we also provide definitive evidence that the iron moiety of SNP is not responsible for such changes. These results indicate that SNP‐mediated increase in ferritin synthesis is, in part, due to an IRP‐independent and NO+‐dependent post‐transcriptional, regulatory mechanism.
Mapping Quantitative Trait Loci for Post‐Anthesis Dry Matter Accumulation in Wheat
Authors: Su Jun‐Ying , Tong Yi‐Ping , Liu Quan‐You , Li Bin , Jing Rui‐Lian , Li Ji‐Yun , Li Zhen‐Sheng
Published: August 2006

Post‐anthesis photoassimilation is very important for wheat (Triticum aestivum L.) grain filling. The aim of the present study was to map quantitative trait loci (QTL) for post‐anthesis dry matter accumulation (DMA). A set of 120 doubled haploid (DH) lines, derived from winter wheat varieties Hanxuan 10 and Lumai 14, was grown under field conditions in two consecutive growing seasons during 2002–2004 in Beijing. Post‐anthesis DMA per culm and related traits, including flag leaf greenness (FLG) and flag leaf weight (FLW; dry weight per flag leaf) at flowering, and grain weight per ear (GWE) were investigated. All traits segregated continuously in the DH population in both trials. The DMA was significantly and positively correlated with GWE, with the correlation coefficients being 0.79 and 0.66 in the 2002–2003 and 2003–2004 growing seasons (both P < 0.01), suggesting the importance of DMA in grain filling. Further correlation analysis showed that FLW was more closely correlated with DMA and GWE than FLG in both growing seasons, indicating that FLW was more important than FLG in influencing DMA and GWE. In total, 30 QTLs for these four traits were mapped and distributed on 10 chromosomes. Phenotypic variations explained by an individual QTL were in the range 5.8%–21.3%, 5.9%–17.2%, 5.1%–18.1%, and 5.6%–16.2% for FLG, FLW, DMA, and GWE, respectively. Eight QTLs for DMA were detected, of which four (on chromosome arms 2AS, 4BL, 5AS, and 7AS) were linked with QTLs for GWE; two (on chromosome arms 5BL and 7BL) coincided with QTLs for FLW. These results may provide useful information for developing marker‐assisted selection for the improvement of DMA.

(Managing editor: Wei Wang)
Characterization of Wheat Random Amplified Polymorphic DNA Markers Associated with the H11 Hessian Fly Resistance Gene
Authors: Bouktila Dhia , Mezghani Maha , Marrakchi Mohamed , Makni Hanem
Published: August 2006

In Tunisia, the Hessian fly Mayetiola destructor Say is a major pest of durum wheat (Triticum durum Desf.) and bread wheat (T. aestivum L.). Genetic resistance is the most efficient and economical method of control of this pest. To date, 31 resistance genes, designated H1–H31, have been identified in wheat. These genes condition resistance to the insect genes responsible for virulence. Using wheat cultivars differing for the presence of an individual Hessian fly resistance gene and random amplified polymorphic DNA (RAPD) analysis, we have identified a polymorphic 386‐bp DNA marker (Xgmib1‐1A.1) associated with the H11 Hessian fly resistance gene. Blast analysis showed a high identity with a short region in the wild wheat (T. monococcum) genome, adjacent to the leaf rust resistance Lr10 gene. A genetic linkage was reported between this gene (Lr10) and Hessian fly response in wheat. These data were used for screening Hessian fly resistance in Tunisian wheat germplasm. Xgmib1‐1A.1‐like fragments were detected in four Tunisian durum and bread wheat varieties. Using these varieties in Hessian fly breeding programs in Tunisia would be of benefit in reducing the damage caused by this fly.

(Managing editor: Li‐Hui Zhao)
Proteomic Alterations of Antarctic Ice Microalga Chlamydomonas sp. Under Low‐Temperature Stress
Authors: Kan Guang‐Feng , Miao Jin‐Lai , Shi Cui‐Juan , Li Guang‐You
Published: August 2006

Antarctic ice microalga can survive and thrive in cold channels or pores in the Antarctic ice layer. In order to understand the adaptive mechanisms to low temperature, in the present study we compared two‐dimensional polyacrylamide gel electrophoresis (2‐DE) profiles of normal and low temperature‐stressed Antarctic ice microalga Chlamydomonas sp. cells. In addition, new protein spots induced by low temperature were identified with peptide mass fingerprinting based on matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) and database searching. Well‐resolved and reproducible 2‐DE patterns of both normal and low temperature‐stressed cells were acquired. A total of 626 spots was detected in control cells and 652 spots were detected in the corresponding low temperature‐stressed cells. A total of 598 spots was matched between normal and stressed cells. Two newly synthesized proteins (a and b) in low temperature‐stressed cells were characterized. Protein spot A (53 kDa, pI 6.0) was similar to isopropylmalate/homocitrate/citramalate synthases, which act in the transport and metabolism of amino acids. Protein spot b (25 kDa, pI 8.0) was related to glutathione S‐transferase, which functions as a scavenger of active oxygen, free radicals, and noxious metabolites. The present study is valuable for the application of ice microalgae, establishing an ice microalga Chlamydomonas sp. proteome database, and screening molecular biomarkers for further studies.

(Managing editor: Li‐Hui Zhao)
Chemical Constituents of Siegesbeckia orientalis L.
Authors: Wang Li‐Li , Hu Li‐Hong
Published: August 2006

The aerial parts of Siegesbeckia have been used as the traditional Chinese medicine in the treatment of rheumatic arthritis, hypertension, malaria, neurasthenia, and snakebite. In order to find new and bioactive compounds, the chemical constituents of the aerial parts of S. orientalis L. were investigated and two new compounds, namely β‐D‐glucopyranosyl‐ent‐2‐oxo‐15,16‐dihydroxy‐pimar‐8(14)‐en‐19‐oic‐late (compound 1) and [1(10)E,4Z]‐8β‐angeloyloxy‐9α‐methoxy‐6α,15‐dihydroxy‐14‐oxogermacra‐1(10),4,11(13)‐trien‐12‐oic acid 12,6‐lactone (compound 2), as well as five known ent‐pimarane diterpenes (compounds 3–7) were isolated. The structures of the two new compounds were identified by their physicochemical properties and spectral analysis, particularly one‐ and two‐dimensional nuclear magnetic resonance spectral methods.

(Managing editor: Wei Wang)
Stipa tenacissima Does not Affect the Foliar δ13C and δ15N of Introduced Shrub Seedlings in a Mediterranean Semi‐arid Steppe
Authors: Maestre Fernando T. , Bautista Susana , Cortina Jordi
Published: August 2006

Recent studies have shown that the tussock grass Stipa tenacissima L. facilitates the establishment of late‐successional shrubs, in what constitutes the first documented case of facilitation of woody plants by grasses. With the aim of increasing our knowledge of this interaction, in the present study we investigated the effects of S. tenacissima on the foliar δ13C, δ15N, nitrogen concentration, and carbon : nitrogen ratio of introduced seedlings of Pistacia lentiscus L., Quercus coccifera L., and Medicago arborea L. in a semi‐arid Mediterranean steppe. Six months after planting, the values of δ13C ranged between −26.9‰ and −29.6‰, whereas those of δ15N ranged between −1.9‰ and 2.7‰. The foliar C : N ratio ranged between 10.7 and 53.5, and the nitrogen concentration ranged between 1.0% and 4.4%. We found no significant effect of the microsite provided by S. tenacissima on these variables in any of the species evaluated. The values of δ13C were negatively correlated with predawn water potentials in M. arborea and were positively correlated with relative growth rate in Q. coccifera. The values of δ15N were positively correlated with the biomass allocation to roots in the latter species. The present results suggest that the modification of environmental conditions in the are surrounding S. tenacissima was not strong enough to modify the foliar isotopic and nitrogen concentration of shrubs during the early stages after planting.

(Managing editor: Ya‐Qin Han)
Effects of Exogenous Spermidine on Photosystem II of Wheat Seedlings Under Water Stress
Authors: Duan Hui‐Guo , Yuan Shu , Liu Wen‐Juan , Xi De‐Hui , Qing Dong‐Hong , Liang Hou‐Guo , Lin Hong‐Hui
Published: August 2006

The effects of exogenous spermidine (Spd) on lipid peroxidation, relative plasma membrane permeability, photosystem II (PSII) gene expression and PSII photochemical activity in water‐stressed wheat seedlings were investigated. The decrease in relative water content (RWC), Chl content, and 2,6‐dichlorophenol indophenol (DCIP) photoreduction of PSII, and increases in electrolyte leakage of plasma membranes and malonyldialdehyde (MDA) in water‐stressed leaves was alleviated by Spd pretreatment. Furthermore, Western and Northern blot analysis showed that decreases in the PSII major proteins D1, D2 and LHCII and the transcripts of corresponding genes psbA, psbD and cab were also alleviated by Spd pretreatment under water stress. These results suggest that the application of exogenous Spd protects PSII against water stress at both the transcriptional level and the translational level, and allows PSII to retain a higher activity level during water stress. The protective role of Spd in the photosynthetic apparatus also is discussed.

(Managing editor: Ping He)
Cloning and Functional Analysis of the Bifunctional Agglutinin/Trypsin Inhibitor from Helianthus tuberosus L.
Authors: Chang Tuanjie , Zhai Hongli , Chen Songbiao , Song Guisheng , Xu Honglin , Wei Xiaoli , Zhu Zhen
Published: August 2006

In order to find new insect resistance genes, four homologous cDNAs, hta‐a, hta‐b, hta‐c and hta‐d with lengths of 775, 718, 784 and 752 bp, respectively (GenBank accession numbers AF477031‐AF477034), were isolated from a tuber cDNA expression library of Helianthus tuberosus L. Sequence analysis revealed that all four cDNAs contain an open reading frame of 444 bp, coding a polypeptide of 147 amino acid residues, and that the sequences of the cDNAs are very similar to those of the mannose‐binding agglutinin genes of the jacalin‐related family. In hemagglutination reactions and hapten inhibition assays, affinity‐purified HTA (Helianthus tuberosus agglutinin) from induced Escherichia coli BL21(DE3) expressing GST‐HTA shows hemagglutination ability and a higher carbohydrate‐binding ability for mannose than other tested sugars. Trypsin inhibitory activity was detected in the crude extracts of induced E. coli BL21(DE3) expressing HTA, and was further verified by trypsin inhibitory activity staining on native polyacrylamide gel. The mechanism of interaction between HTA and trypsin was studied by molecular modeling. We found that plenty of hydrogen bonds and electrostatic interactions can be formed between the supposed binding sites of HTA‐b and the active site of trypsin, and that a stable HTA/trypsin complex can be formed. The results above imply that HTA might be a bifunctional protein with carbohydrate‐binding activity and trypsin inhibitory activity. Moreover, Northern blotting analysis demonstrated that hta is predominantly expressed in tubers of H. tuberosus, very weakly expressed in stems, but not expressed at all in other tissues. Southern blotting analysis indicated that hta is encoded by a multi‐gene family. The insect resistance traits have been described in another paper.

(Managing editor: Li‐Hui Zhao)
Potentiel de Productivité et Efficacité Technique du Secteur Agricole en Afrique
Authors: Nyemeck Joachim Binam , Nkamleu Guy Blaise
Published: August 2006

This study utilizes frontier metaproduction functions to analyze inter‐region agricultural productivity differences. Technical efficiency scores are examined through estimation of stochastic frontiers for 16 African countries divided into three different regions (West Africa, East and Southern Africa, and North Africa) from 1970 to 2001. The idea is to explore the differences in efficiency and technological gaps of agricultural sector. Apart of common traits that characterize African agricultural sector, countries exhibit national and regional specificities. These diversities are such that it is difficult to make valuable generalizations. It appears from the results that: in West Africa, the level of technology is relatively good, meaning that there is no problem of input constraints. By contrast, the efficiency with which inputs are used is very low. The situation is very different in the East and Southern Africa, with the level of technology relatively low and appreciable technical level. At least, the North Africa countries make a performing mixture between technology and efficiency.

Cette étude utilise les Meta frontières de production pour analyser les différences inter‐régionales de la productivité agricole. Les niveaux d'efficacité technique sont examinées par l'estimation des frontières stochastiques de 16 pays africains regroupés en trois régions (l'Afrique de l'Ouest, l'Afrique de l'Est et Australe, et l'Afrique du Nord), sur une période allant de 1970 à 2001. L'idée étant d'explorer les différences d'efficacité et les écarts technologiques du secteur agricole. Au‐delà des simples traits communs qui caractérisent le secteur agricole africain, on trouve des expériences nationales et régionales dont il est difficile, du fait de leur grande diversité, de tirer des généralisations valables. Des résultats de l'étude, il ressort que: en Afrique de l'Ouest, le niveau technologique est relativement satisfaisant, traduisant le fait que la présence des inputs ne représente pas une contrainte. Par contre le niveau d'efficacité avec lequel ces intrants sont utilisés est assez faible. La situation est tout autre en Afrique de l'Est et Australe avec un niveau technologique relativement faible et un niveau d'efficacité appréciable. L'Afrique du nord enfin fait un savant dosage entre efficacité et technologie.
Highly Selective Cyclic Peptide Ligands for NeutrAvidin and Avidin Identified by Phage Display
Authors: Meyer Scott C. , Gaj Thomas , Ghosh Indraneel
Published: August 2006

Screening combinatorial libraries of conformationally constrained peptides against macromolecular targets is utilized in identifying novel drug leads and in developing new reagents for chemical biology. In methods such as phage‐display selections, biotinylated macromolecular targets are often immobilized on avidin‐ and streptavidin‐functionalized supports. Thus, the characterization of peptides that bind avidin and streptavidin is necessary for accurate interpretation of screening and selection results. Toward this goal, we panned a phage‐displayed cyclic peptide library against NeutrAvidin, a chemically deglycosylated version of avidin. The selection produced a highly homologous consensus motif (Asp‐Arg/Leu‐Ala‐Ser/Thr‐Pro‐Tyr/Trp). Two of these cyclic peptides, CDRATPYC and CDRASPYC, bound both NeutrAvidin and avidin with low‐micromolar dissociation constants, whereas their acyclic counterparts had negligible affinity (<80‐fold). Moreover, these cyclic peptides were very specific for their targets and did not bind the structurally and functionally similar protein, streptavidin. Thus, we have identified a new class of cyclic peptides, distinct from the much‐studied streptavidin‐binding His‐Pro‐Gln peptide motif. These results will not only allow for discriminating between desired and background cyclic peptide motifs in selections and screens but also provide a new protein/peptide model system and a useful reagent in chemical biology that can have utility in protein immobilization, purification, and chemical tagging.
Temperature Effect on Inactivation Kinetics of Escherichia coli O157:H7 by Electron Beam in Ground Beef, Chicken Breast Meat, and Trout Fillets
Authors: Black J.L. , Jaczynski J.
Published: August 2006

ABSTRACT:  Ground beef, boneless skinless chicken breast meat, and boneless skinless trout fillets were inoculated with Escherichia coli O157:H7 and incubated to approximately 109 colony forming units per gram (CFU/g). Following incubation, temperature of the meat samples was equilibrated to −20, 4, and 22 °C. The meat samples at different temperatures were subjected to one‐sided electron beam (e‐beam) with fixed energy at 10 million electron volts (MeV) and doses at 0 (control), 0.5, 1.0, 2.0, 2.5, and 3.0 kGy. The survivors were enumerated using a standard spread‐plating method. The survivor curves were plotted on logarithmic scale as a function of e‐beam dose for each meat sample subjected to e‐beam at different temperatures. The D‐values were calculated as a negative reciprocal of the slope of the survivor curves. The D‐values for E. coli ranged from 0.22 to 0.35 kGy in trout at 4 °C and chicken at −20 °C, respectively. The D‐values were different between meat types. Regardless of temperature, E. coli in chicken had highest D‐value followed by beef and trout. The D‐values for E. coli in frozen samples were higher than D‐values in samples irradiated at 4 and 22 °C regardless of species. Although there were numerical differences between D‐values for samples subjected to e‐beam while chilled (4 °C) or frozen (−20 °C), they were statistically insignificant. Water radiolysis is considered as an indirect mechanism for microbial inactivation. Therefore, while the physical state of water (frozen or unfrozen) in foods seems the major contributor to microbial inactivation by e‐beam due to water radiolysis, product temperature most likely plays a minor role.
Characteristics of Sodium Caseinate‐ and Soy Protein Isolate‐Stabilized Emulsion‐Gels Formed by Microbial Transglutaminase
Authors: Lee Hyun A. , Choi Seung J. , Moon Tae W.
Published: August 2006

ABSTRACT:  Protein‐stabilized emulsion gels were prepared via microbial transglutaminase (mTGase) catalysis, and their physicochemical characteristics were examined. Emulsion oil droplet size and interfacial protein load were measured. The sodium caseinate and soy protein isolate emulsion gels exhibited different microstructures and physical properties. The emulsion gels improved the storage stability of aroma compounds. Rheological measurements of the emulsion gels revealed interesting strength, gelation kinetics, and thermal sensitivity properties. The mTGase‐induced emulsion gels comprised a fine network which led to less release of aroma compounds upon storage than did emulsions. These results suggest that emulsion gels may be used to improve the texture of food emulsions and to control release of food aromas.
Synthesis of Diacylglycerols Containing CLA by Lipase‐Catalyzed Esterification
Authors: Kim In‐Hwan , Lee Sun‐Mi
Published: August 2006

ABSTRACT:  Diacylglycerols (DAG) were prepared by esterification of glycerol with conjugated linoleic acid (CLA) in the presence of an immobilized 1,3‐regiospecific lipase from Rhizomucor miehei and vacuum conditions. The effects of several parameters, namely, temperature, enzyme loading, stirring speed, and vacuum, on the concentration and the purity of the DAG were studied. The reaction temperature influenced both the reaction rate and the concentration of the DAG. The rate of DAG synthesis increased as the enzyme loading increased. However, for high enzyme loadings, the concentration of triacylglycerols (TAG) increased significantly at long reaction times and, as a result, the purity of the DAG decreased. When the stirring speed increased from 150 to 450 rpm, the DAG concentration increased significantly. However, at stirring speeds above 450 rpm, no significant increases in DAG concentration were observed. When the pressure was decreased from 20 to 3 mmHg, the maximum concentration of DAG increased from 76.0% to 80.5%. No increase in the DAG concentration was observed when the pressure was decreased from 3 to 1 mm Hg, even though a slightly higher DAG purity was achieved at 1 mm Hg. For the range of absolute pressures tested, the concentrations of 1,2‐DAG were less than 1%.
Consumer Valuations and Preference Heterogeneity for a Novel Functional Food
Authors: Teratanavat Ratapol , Hooker Neal H.
Published: August 2006

ABSTRACT:  Recent trends in the marketing of functional foods suggest that multiple‐benefit products are becoming more common. Yet it is unclear which consumers are most interested in, or best served by, such novel or new generation functional foods. With emerging scientific evidence of efficacy and more diverse products offered for sale, a broader range of consumers are likely to become interested in dietary interventions to enhance health. Consumers will likely respond based on a range of motivation, health conditions, and knowledge levels suggesting “one size will not fit all.” Given such an evolving marketing environment, this paper presents 1 research technique exploring differences in consumer preferences and valuations for a novel functional food product—a tomato juice containing soy. A discrete choice experiment is applied to examine consumer valuation of this novel functional food. Data were collected from 1704 households in Ohio through a mail survey. The choice experiment manipulates whether or not the product is organic, whether it contains natural or fortified nutrients, and product price. Estimates of consumer willingness to pay a premium price are based on conditional logit and mixed logit models, which permit an examination of consumer preference and valuation heterogeneity for key product attributes. Results indicate that health benefits and ingredient naturalness are positively valued, but such preferences and valuations depend on an individual's education, income, and food purchase behavior. Naturally occurring nutrients are preferred over fortification. Considerable heterogeneity is found in the data suggesting that a range of market segments may exist.
Surgical treatment of extensive chondroid formation in the guttural pouch of a Warmblood horse
Authors: SCHAAF KL , KANNEGIETER NJ , LOVELL DK
Published: August 2006

A Warmblood horse presented with a purulent nasal discharge that had failed to respond to antibiotic therapy. Radiography and endoscopy confirmed a large number of chondroid masses (over 200) in the left guttural pouch. Despite the large number of chondroids present, there was no external swelling evident. The masses were surgically removed via a hyovertebrotomy approach that provided excellent exposure, and no postoperative complications were encountered. Long term follow‐up (3 years) confirmed a successful outcome.
Hydrops fetalis associated with pulmonary hypoplasia in Dexter calves
Authors: WINDSOR PA , CAVANAGH JAL , TAMMEN I
Published: August 2006

The occurrence of severe fetal dystocia due to hydrops fetalis associated with pulmonary aplasia in two male and pulmonary hypoplasia in one female Australian Dexter fetuses from two herds is described. Obstetrical intervention by caesarean section was required for delivery of the fetuses, with mortalities in one dam and the 3 calves. Clinical, pathological and genetic features are tabulated to assist in distinguishing pulmonary hypoplasia‐associated hydrops fetalis from the more prevalent disorder of chondrodysplasia in Dexter cattle. Anasarca and complete absence or presence of only rudimentary lung tissue in a large thoracic cavity clearly distinguishes this entity from the lesions of Dexter chondrodysplasia that include severe micromelia and abundant lung tissue in a small thoracic cavity with shortened spine and rib cage. Pedigree information suggested that Dexter hydrops may be transmitted in an autosomal recessive manner.
Direct Molecular Approach to Monitoring Bacterial Colonization on Vacuum-Packaged Beef
Authors: Fontana Cecilia , Cocconcelli Pier Sandro , Vignolo Graciela
Published: August 2006

Denaturing gradient gel electrophoresis allowed us to monitor total bacterial communities and to establish a pattern of succession between species in vacuum-packaged beef stored at 2 and 8°C for 9 weeks and 14 days. Species-specific PCR was used to confirm the presence of
Lactobacillus sakei
and
Lactobacillus curvatus
. Multiplex PCRs using 16S rRNA-specific primers allowed differentiation between
Leuconostoc
species. These methods provided the desired information about microbial diversity by detecting the main microorganisms capable of colonizing this ecological niche.
Application of Bacteriophages To Control Intestinal
Escherichia coli
O157:H7 Levels in Ruminants
Authors: Sheng Haiqing , Knecht Hannah J. , Kudva Indira T. , Hovde Carolyn J.
Published: August 2006

A previously characterized O157-specific lytic bacteriophage KH1 and a newly isolated phage designated SH1 were tested, alone or in combination, for reducing intestinal
Escherichia coli
O157:H7 in animals. Oral treatment with phage KH1 did not reduce the intestinal
E. coli
O157:H7 in sheep. Phage SH1 formed clear and relatively larger plaques on lawns of all 12
E. coli
O157:H7 isolates tested and had a broader host range than phage KH1, lysing O55:H6 and 18 of 120 non-O157
E. coli
isolates tested. In vitro, mucin or bovine mucus did not inhibit bacterial lysis by phage SH1 or KH1. A phage treatment protocol was optimized using a mouse model of
E. coli
O157:H7 intestinal carriage. Oral treatment with SH1 or a mixture of SH1 and KH1 at phage/bacterium ratios ≥10
2
terminated the presence of fecal
E. coli
O157:H7 within 2 to 6 days after phage treatment. Untreated control mice remained culture positive for >10 days. To optimize bacterial carriage and phage delivery in cattle,
E. coli
O157:H7 was applied rectally to Holstein steers 7 days before the administration of 10
10
PFU SH1 and KH1. Phages were applied directly to the rectoanal junction mucosa at phage/bacterium ratios calculated to be ≥10
2
. In addition, phages were maintained at 10
6
PFU/ml in the drinking water of the phage treatment group. This phage therapy reduced the average number of
E. coli
O157:H7 CFU among phage-treated steers compared to control steers (
P
< 0.05); however, it did not eliminate the bacteria from the majority of steers.
Identification and Preliminary Characterization of Two cDNAs Encoding Unique Carbonic Anhydrases from the Marine Alga
Emiliania huxleyi
Authors: Soto Amelia R. , Zheng Hong , Shoemaker Dorinda , Rodriguez Jason , Read Betsy A. , Wahlund Thomas M.
Published: August 2006

Marine coccolithophorid algae are thought to play a significant role in carbon cycling due to their ability to incorporate dissolved inorganic carbon (DIC) into both calcite and photosynthetic products. Among coccolithophorids,
Emiliania huxleyi
is the most prolific, forming massive blooms that affect the global environment. In addition to its ecological importance, the elaborate calcite structures (coccoliths) are being investigated for the design of potential materials for science and biotechnological devices. To date, most of the research focus in this organism has involved the partitioning of DIC between calcification and photosynthesis, primarily using measurements of an external versus internal carbonic anhydrase (CA) activity under defined conditions. The actual genes, proteins, and pathways employed in these processes have not been identified and characterized (see the work of Quinn et al. in this issue [P. Quinn, R. M. Bowers, X. Zhang, T. M. Wahlund, M. A. Fanelli, D. Olszova, and B. A. Read, Appl. Environ. Microbiol. 72:5512-5526, 2006]). In this study, the cloning and preliminary characterization of two genetically distinct carbonic anhydrase cDNAs are described. Phylogenetic analysis indicated that these two genes belonged to the gamma (γ-EhCA2) and delta (δ-EhCA1) classes of carbonic anhydrases. The deduced amino acid sequence of δ-EhCA1 revealed that it encodes a protein of 702 amino acids (aa) (ca. 77.3 kDa), with a transmembrane N-terminal region of 373 aa and an in-frame C-terminal open reading frame of 329 aa that defines the CA region. The γ-EhCA2 protein was 235 aa in length (ca. 24.9 kDa) and was successfully expressed in
Escherichia coli
BL21(DE3) and purified as an active recombinant CA. The expression levels of each transcript from quantitative reverse transcription-PCR experiments under bicarbonate limitation and over a 24-h time course suggest that these isozymes perform different functions in
E. huxleyi
.
Multiple Microfermentor Battery: a Versatile Tool for Use with Automated Parallel Cultures of Microorganisms Producing Recombinant Proteins and for Optimization of Cultivation Protocols
Authors: Frachon Emmanuel , Bondet Vincent , Munier-Lehmann Hélène , Bellalou Jacques
Published: August 2006

A multiple microfermentor battery was designed for high-throughput recombinant protein production in
Escherichia coli
. This novel system comprises eight aerated glass reactors with a working volume of 80 ml and a moving external optical sensor for measuring optical densities at 600 nm (OD
600
) ranging from 0.05 to 100 online. Each reactor can be fitted with miniature probes to monitor temperature, dissolved oxygen (DO), and pH. Independent temperature regulation for each vessel is obtained with heating/cooling Peltier devices. Data from pH, DO, and turbidity sensors are collected on a FieldPoint (National Instruments) I/O interface and are processed and recorded by a LabVIEW program on a personal computer, which enables feedback control of the culture parameters. A high-density medium formulation was designed, which enabled us to grow
E. coli
to OD
600
up to 100 in batch cultures with oxygen-enriched aeration. Accordingly, the biomass and the amount of recombinant protein produced in a 70-ml culture were at least equivalent to the biomass and the amount of recombinant protein obtained in a Fernbach flask with 1 liter of conventional medium. Thus, the microfermentor battery appears to be well suited for automated parallel cultures and process optimization, such as that needed for structural genomics projects.
Comparative, Collaborative, and On-Site Validation of a TaqMan PCR Method as a Tool for Certified Production of Fresh,
Campylobacter
-Free Chickens
Authors: Krause M. , Josefsen M. H. , Lund M. , Jacobsen N. R. , Brorsen L. , Moos M. , Stockmarr A. , Hoorfar J.
Published: August 2006

Certified
Campylobacter
-free poultry products have been produced in Denmark since 2002, the first example of fresh (unprocessed and nonfrozen) chickens labeled “
Campylobacter
free.” This success occurred partly through use of a 4-hour gel-based PCR testing scheme on fecal swabs. In this study, a faster, real-time PCR approach was validated in comparative and collaborative trials, based on recommendations from the Nordic system for validation of alternative microbiological methods (NordVal). The comparative real-time PCR trial was performed in comparison to two reference culture protocols on naturally contaminated samples (99 shoe covers, 101 cloacal swabs, 102 neck skins from abattoirs, and 100 retail neck skins). Culturing included enrichment in both Bolton and Preston broths followed by isolation on Preston agar and mCCDA. In one or both culture protocols, 169 samples were identified as positive. The comparative trial resulted in relative accuracy, sensitivity, and specificity of 98%, 95%, and 97%, respectively. The collaborative trial included nine laboratories testing neck skin, cloacal swab, and shoe cover samples, spiked with low, medium, and high concentrations of
Campylobacter jejuni
. Valid results were obtained from six of the participating laboratories. Accuracy for high levels was 100% for neck skin and cloacal swab samples. For low levels, accuracy was 100% and 92% for neck skin and cloacal swab samples, respectively; however, detection in shoe cover samples failed. A second collaborative trial, with an optimized DNA extraction procedure, gave 100% accuracy results for all three spiking levels. Finally, on-site validation at the abattoir on a flock basis was performed on 400 samples. Real-time PCR correctly identified 10 of 20 flocks as positive; thus, the method fulfilled the NordVal validation criteria and has since been implemented at a major abattoir.