| 1. |
- Beaujean, A, et al.
(author)
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Engineering direct fructose production in processed potato tubers by expressing a bifunctional alpha-amylase/glucose isomerase gene complex
- 2000
-
In: Biotechnology and Bioengineering. - 0006-3592. ; 70:1, s. 9-16
-
Journal article (peer-reviewed)abstract
- Manipulation of starch biosynthesis/degradation and formation of novel molecules in storage organs of plants through genetic engineering is an attractive but technically challenging goal. We report here, for the first time, that starch was degraded and glucose and fructose were produced directly when crushed potato tubers expressing a starch degrading bifunctional gene were heated for 45 minutes at 65 degrees C. To achieve this, we have constructed a fusion gene encoding the thermostable enzymes: alpha-amylase (Bacillus stearothermophilus) and glucose isomerase (Thermus thermophilus). The chimeric gene was placed under the control of the granule-bound-starch synthase promoter. This enzymatic complex produced in transgenic tubers was only active at high temperature (65 degrees C). More than 100 independent transgenic potato plants were regenerated. Molecular analyses confirmed the stable integration of the chimeric gene into the potato genome. The biochemical analyses performed on young and old tubers after high-temperature treatment (65 degrees C) revealed an increase in the formation rate of fructose and glucose by a factor of 16.4 and 5. 7, respectively, in the transgenic tubers as compared to untransformed control tubers. No adverse discernible effect on plant development and metabolism including tuber formation and starch accumulation was observed in the transgenic plants before heat treatment. Our results demonstrate that it is possible to replace starch degradation using microbial enzymes via a system where the enzymes are produced directly in the plants, but active only at high temperature, thus offering novel and viable strategies for starch-processing industries.
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| 2. |
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| 3. |
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| 4. |
- Gavrilets, Sergey, et al.
(author)
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The evolution of female mate choice by sexual conflict
- 2001
-
In: Proceedings of the Royal Society of London Series B. - London : The Roylal Society. - 0080-4649 .- 0962-8452 .- 1471-2954. ; 268:1466, s. 531-539
-
Journal article (peer-reviewed)abstract
- Although empirical evidence has shown that many male traits have evolved via sexual selection by female mate choice, our understanding of the adaptive value of female mating preferences is still very incomplete. It has recently been suggested that female mate choice may result from females evolving resistance rather than attraction to males, but this has been disputed. Here, we develop a quantitative genetic model showing that sexual conflict over mating indeed results in the joint evolution of costly female mate choice and exaggerated male traits under a wide range of circumstances. In contrast to traditional explanations of costly female mate choice, which rely on indirect genetic benefits, our model shows that mate choice can be generated as a side–effect of females evolving to reduce the direct costs of mating.
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| 5. |
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| 6. |
- Lundälv, Jörgen, 1966
(author)
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Bioterrorism och media
- 2004
-
Book (other academic/artistic)abstract
- Attacker med biologiska och kemiska preparat är ett nytt hot mot institutioner i världen bl.a massmedia. I USA har ett antal medieföretag attackerats med brev som visat sig innehålla mjältbrand. I Sverige utsätts medier för hot och risker med jämna mellanrum. Denna guide om säkerhet och beredskap ger ny kunskap om vad bioterrorism innebär och vilka hotbilder som finns mot medieföretag i Sverige. Den vänder sig också till informationsstrateger vid myndigheter och företag liksom till hälso- och sjukvårdspersonal med intresse för epidemiologiska frågor. Guiden inleds med företal av Gorm Albrechtsen, f.d. chefredaktör vid Herning Folkeblad i Danmark som utsatts för misstänkta pulverbrev samt av Åke Sellström, avdelningschef vid Totalförsvarets forskningsinstitut (FOI) och expert på biologiska och kemiska vapen.
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| 7. |
- Schrader, J., et al.
(author)
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Cambial meristem dormancy in trees involves extensive remodelling of the transcriptome
- 2004
-
In: The Plant Journal. - Malden : Wiley-Blackwell. - 0960-7412 .- 1365-313X. ; 40:2, s. 173-187
-
Journal article (peer-reviewed)abstract
- The establishment of the dormant state in meristems involves considerable physiological and metabolic alterations necessary for surviving unfavourable growth conditions. However, a global molecular analysis of dormancy in meristems has been hampered by the difficulty in isolating meristem cells. We used cryosectioning to isolate purified cambial meristem cells from the woody plant Populus tremula during active growth and dormancy. These samples were used to generate meristem-specific cDNA libraries and for cDNA microarray experiments to define the global transcriptional changes underlying cambial dormancy. The results indicate a significant reduction in the complexity of the cambial transcriptome in the dormant state. Although cell division is terminated in the dormant cambium, the cell cycle machinery appears to be maintained in a skeletal state as suggested by the continued presence of transcripts for several cell cycle regulators. The downregulation of PttPIN1 and PttPIN2 transcripts explains the reduced basipetal polar auxin transport during dormancy. The induction of a member of the SINA family of ubiquitin ligases implicated in auxin signalling indicates a potential mechanism for modulation of auxin sensitivity during cambial dormancy. The metabolic alterations during dormancy are mirrored in the induction of genes involved in starch breakdown and the glyoxysomal cycle. Interestingly, the induction of RGA1 like gene suggests modification of gibberellin signalling in cambial dormancy. The induction of genes such as poplar orthologues of FIE and HAP2 indicates a potential role for these global regulators of transcription in orchestrating extensive changes in gene expression during dormancy.
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| 8. |
- Teeri, Tuula T.
(author)
-
Genome sequence of an omnipotent fungus
- 2004
-
In: Nature Biotechnology. - : Springer Science and Business Media LLC. - 1087-0156 .- 1546-1696. ; 22:6, s. 679-680
-
Journal article (peer-reviewed)
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| 9. |
- Routh, Joyanto, 1968-, et al.
(author)
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Volatile organic acids and microbial processes in the Yegua formation, east-central Texas
- 2001
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In: Applied Geochemistry. - : Elsevier. - 0883-2927 .- 1872-9134. ; 16:2, s. 183-195
-
Journal article (peer-reviewed)abstract
- Geochemical and microbiological evidence indicates that viable microorganisms produce and consume volatile organic acids (VOA) in the Yegua formation. Acetic and propionic acid concentrations in mudstones range from 200 to 1270 and 20 to 38 nmol·gdw−1 respectively, whereas concentrations in sands are 50–200 and less than 20 nmol·gdw−1. VOA concentrations in sediments and in laboratory incubations suggest net production of VOAs by microorganisms in mudstones, and net consumption of VOAs by SO4 reducing bacteria (SRB) in sands. Notably, SRB activity is mostly confined to aquifer sands. Vertical diffusion and advection were modeled to estimate acetic acid transport from aquitard to aquifer. Assuming that SRB completely respire the acetic acid transported into the aquifer (3.2 μmol·l−1·m·a−1), the CO2 production rate in the aquifer sands is 5.3 μmol·l−1·a−1. This slow mineralization rate of in situ organic matter is within the range for deep aquifers, and probably accounts for the long-term survival of microorganisms in oligotrophic environments. Finally, the microbial communities in Yegua sediments appear to exhibit a loose commensalism, with microorganisms in aquitards providing VOAs for respiratory processes (i.e., SO4 reduction) in aquifers.
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| 10. |
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| 11. |
- Öhman, Marcus, et al.
(author)
-
Reasons for slagging during stemwood pellet combustion and some measures for prevention
- 2004
-
In: Biomass and Bioenergy. - Oxford : Pergamon Press. - 0961-9534 .- 1873-2909. ; 27:6, s. 597-605
-
Journal article (peer-reviewed)abstract
- Ash related problems have more than occasionally been observed in pellet burners during the last years. These problems lead to reduced accessibility of the appliances and also bad publicity for the pellet market. The objectives of the present work were therefore to: (i) determine the critical levels of the problematic ash components in stemwood pellets regarding slagging, (ii) document the variations of these problematic elements in the outgoing pellets from two pellet-mills during one operational season, (iii) determine how frequently these elements exceed the critical levels, (iv) determine how different sub-processes in the pelletising process (especially the dryer) effect the slagging properties of the pellet, and if possible (v) suggest some measures for prevention. A significant number of wood pellets reported to be problematic and problem-free, regarding slagging in ordinary residential pellet burners, were collected from the Swedish market. The ash compositions of these fuels were analysed and the results compiled in a database. Partial Least-Squares Discriminant Analysis (PLS-DA) and F-tests were used to statistically identify both the critical ash components and the critical levels of these components that separated the two reported classes. In addition, chemical equilibrium model calculations were used to interpret the findings. The variations of these elements in the in-going raw material and in the produced pellets were determined during one season in two pellet mills equipped with exhaust gas dryers. The results showed that the problematic wood-pellets had a significantly higher amount of Si, but also Al and Fe, in the fuel ash. The critical level of Si (given as SiO2) was about 20-25 wt% of the fuel ash, i.e. pellets with levels in or over this range resulted in slagging problems in residential burners. This critical Si content was exceeded once and twice for the analysed samples in the two studied pellet mills. In one of the studied mills, this was because of contamination by sand of the raw material during storage and handling, and in the other mill the reason was found to be contamination of the raw material by elutriated particles from the dryer fuel. The major conclusion of the work is that both raw materials and drying fuels/processes should be carefully treated to avoid mineral contamination, and an additional cyclone separator could potentially also be used to improve the pellet quality.
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| 12. |
- Savolainen, Peter, et al.
(author)
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A detailed picture of the origin of the Australian dingo, obtained from the study of mitochondrial DNA
- 2004
-
In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 101:33, s. 12387-12390
-
Journal article (peer-reviewed)abstract
- To determine the origin and time of arrival to Australia of the dingo, 582 bp of the mtDNA control region were analyzed in 211 Australian dingoes sampled in all states of Australia, 676 dogs from all continents, and 38 Eurasian wolves, and 263 bp were analyzed in 19 pre-European archaeological dog samples from Polynesia. We found that all mtDNA sequences among dingoes were either identical to or differing by a single substitution from a single mtDNA type, A29. This mtDNA type, which was present in >50% of the dingoes, was found also among domestic dogs, but only in dogs from East Asia and Arctic America, whereas 18 of the 19 other types were unique to dingoes. The mean genetic distance to A29 among the dingo mtDNA sequences indicates an origin approximate to5,000 years ago. From these results a detailed scenario of the origin and history of the dingo can be derived: dingoes have an origin from domesticated dogs coming from East Asia, possibly in connection with the Austronesian expansion into Island Southeast Asia. They were introduced from a small population of dogs, possibly at a single occasion, and have since lived isolated from other dog populations.
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| 13. |
- Denoyes-Rothan, B, et al.
(author)
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QTL analysis for resistances to Colletotrichum acutatum and Phytophthora cactorum in octoploid strawberry (Fragaria x ananassa)
- 2004
-
In: Proceedings of the XIth Eucarpia Symposium on Fruit Breeding and Genetics, Vols 1 and 2. - : INTERNATIONAL SOCIETY HORTICULTURAL SCIENCE. ; , s. 147-151
-
Conference paper (peer-reviewed)abstract
- Colletotrichum acutatum and Phytophthora cactorum are two of the most important pathogens of strawberry in Europe, and particularly in France. The characterization of quantitative trait loci (QTL) controlling resistances to these two pathogens would allow a better knowledge of the genetic architecture of these resistances in order to develop durable resistance. A pseudo-testcross strawberry population derived from the cross between Capitola and CF1116 was used for detecting QTLs associated with C. acutatum and P cactorum resistances. One hundred and eighty five individuals were inoculated with C. acutatum by dipping cold stored plants in a conidial suspension adjusted to 2.10(6) conidia per ml. They were also inoculated separately with P cactorum by inserting an agar disk containing mycelium into the crown. Each inoculation was conducted twice. Putative QTLs for resistance to C acutatum and P cactorum were identified by Interval Mapping (Mapmaker-QTL) using a LOD threshold of 2.
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| 14. |
- Lerceteau, Estelle, et al.
(author)
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AFLP mapping and detection of quantitative trait loci (QTLs) for economically important traits in Pinus sylvestris : a preliminary study
- 2000
-
In: Molecular breeding. - : KLUWER ACADEMIC PUBL. - 1380-3743 .- 1572-9788. ; 6:5, s. 451-458
-
Journal article (peer-reviewed)abstract
- We have applied a two-way pseudo-testcross strategy in an analysis of Pinus sylvestris for genetic mapping and detection of quantitative trait loci (QTLs) associated with economically important traits targeted in the Swedish tree-breeding programme. Based on 94 full-sib progeny of a cross between two plus-trees from northern Sweden we generated two parental maps using AFLP markers. The female map was comprised of 94 markers assigned to 15 linkage groups giving a size of 796 cM. On the male map 155 markers were assigned to 15 linkage groups, giving a total size of 1335 cM. The recombination frequency was found to be sex-dependent, being 29.3% higher in male than in female gametes. On the female map, 12 QTLs were detected (but none for branch diameter or wood density). Three QTLs for tree height accounted for 25.8% of the total phenotypic variation of this trait. When the QTLs detected for all the traits were taken independently, the percentages of phenotypic variance ranged from 9.3% to 22.7%. The highest value was observed for frost hardiness, an important trait in northern Sweden for which a major gene seemed to be involved. A cluster of QTLs for tree height, trunk diameter and volume was located on one linkage group. On the male map, four QTLs for trunk diameter and volume were detected. Due to the reduced number of individuals under study, the results are preliminary and have to be validated on more trees.
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| 15. |
- Lerceteau, Estelle, et al.
(author)
-
Detection of quantitative trait loci in Pinus sylvestris L. across years
- 2001
-
In: Euphytica. - : KLUWER ACADEMIC PUBL. - 0014-2336 .- 1573-5060. ; 121:2, s. 117-122
-
Journal article (peer-reviewed)abstract
- In an earlier study, we reported the characterisation of quantitative trait loci (QTLs) for economically important traits related to wood production for a specific year of measurement. However, validating the detected QTLs across years is important for any strategy for marker-assisted selection (MAS). Therefore, we evaluated the consistency of the QTLs across four years in 9 to 12 year-old trees. Data related to tree height were analysed in two ways. The total height was used to characterise QTLs likely to be useful in MAS, and the increment values to evaluate growth regulation. Among the 11 QTLs detected, 4 were found in both the 1996 and 1997 evaluations. QTL numbers and locations related to total height were found to be highly stable. However, the QTL effects progressively changed in successive years, following either an increasing, decreasing or curvilinear trend. Depending on their specific trends, some QTLs may not be expressed at all later in maturity, or they may be expressed at a higher level. This will have direct consequences on the applicability of molecular markers in early screening programs, since a study at the mature stage may also be required. More variation in QTL number and effect was observed relating to height increment than to total height, indicating significant differences in gene expression during the growth periods involved.
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| 16. |
- Lerceteau-Köhler, Estelle, et al.
(author)
-
Characterization of mixed disomic and polysomic inheritance in the octoploid strawberry (Fragaria x ananassa) using AFLP mapping
- 2003
-
In: Theoretical and Applied Genetics. - : SPRINGER-VERLAG. - 0040-5752 .- 1432-2242. ; 107:4, s. 619-628
-
Journal article (peer-reviewed)abstract
- A two-way pseudo-testcross strategy, combined with Single Dose Restriction Fragment (SDRF) marker analysis, was used for genetic mapping in the octoploid cultivated strawberry Fragaria x ananassa (2n=8x=56). Based on a 113 full-sib progeny from a cross between the variety Capitola and the clone CF1116, we generated two parental maps using Amplified Fragment Length Polymorphism (AFLP) markers. Ninety two percent of the markers (727 out of 789) showed ratios corresponding to simplex markers (the majority being SDRF markers), and 8% (62 out of 789) fitted a multiplex ratio. Linkage maps were first established using SDRF markers in coupling phase. The female map comprised 235 markers distributed among 43 co-segregation groups, giving a map size of 1,604 cM. On the male map, 280 markers were assigned to 43 co-segregation groups, yielding a map size of 1,496 cM. Once the co-segregation groups were established, their association was tested using repulsion-phase markers. In total, taking into account associations representing the same linkage groups, 30 linkage groups were detected on the female side and 28 on the male side. On the female map, 68.3% of the pairwise marker linkages were in coupling versus 31.7% in repulsion phase, and the corresponding figures on the male map were 72.2% and 27.8%, respectively. In addition, both groups linked only in the coupling phase and groups linked in the repulsion phase were characterized. The observations suggest that the meiotic behavior of the F. x ananassa genome is neither fully disomic nor fully polysomic, but rather mixed. The genome may not be as completely diploidized as previously assumed.
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| 17. |
- Lerceteau-Köhler, Estelle, et al.
(author)
-
Development of a SCAR marker linked to dominant gene conferring resistance to Colletotrichum acutatum in strawberry (Fragaria x ananassa)
- 2003
-
In: BERRY CROP BREEDING, PRODUCTION AND UTILIZATION FOR A NEW CENTURY. - : INTERNATIONAL SOCIETY HORTICULTURAL SCIENCE. ; , s. 85-91
-
Conference paper (peer-reviewed)abstract
- Colletotrichum acutatum is responsible for strawberry anthracnose, one of the main disease of cultivated strawberry in the south-western area of France (60% of the French production). Anthracnose is a polycyclic disease for which no efficient disease control method has been developed. Therefore, the development of cultivars with sustainable resistance, i.e. efficient against the two pathogenicity groups, may be promising to lower both the level of damage and the use of chemicals. The objective of this study is to identify molecular markers linked to the major dominant gene conferring resistance to pathogenicity group 2 by using an approach of Bulk Segregant Analysis (BSA) and Amplified Fragment Length Polymorphisin (AFLP) markers. We identified four molecular markers, named mf1 to mf4, linked to the resistance gene to the pathogenicity group 2 of C. acutatum. Within a segregating population (back cross type) for the dominant gene, no recombination between the resistance allele and the marker mf3 was detected in 78 BC1 individuals studied. One Sequence Characterized Amplified Region (SCAR) obtained from mf4 (SCAR-mf4) provided a fast and easy test for selection of anthracnose resistant plants at early stage, with a misidentification rate of 1.3%. The evaluation of this SCAR marker in few strawberry varieties showed that only some resistant varieties possessed this marker.
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| 18. |
- Lerceteau-Köhler, Estelle, et al.
(author)
-
QTL analysis for fruit quality traits and resistance to Colletotrichum acutatum and Phytophthora cactorum in octoploid strawberry (Fragaria x ananassa)
- 2004
-
In: PROCEEDINGS OF THE EURO BERRY SYMPOSIUM - COST 836 FINAL WORSKHOP. - : INT SOC HORTICULTURAL SCIENCE. ; , s. 93-97
-
Conference paper (peer-reviewed)abstract
- Mapping of quantitative trait loci (QTL) controlling components of strawberry (Fragaria x ananassa Duch., 2n=8x=56) fruit quality and resistance to Colletotrichum acutatum and Phytophthora cactorum can be used to provide a better understanding of the genetic control of the traits, and to develop marker assisted selection for breeders. A segregating population of 213 individuals of a cross between ‘Capitola’ and ‘CF1116’, two genotypes with many contrasting fruit quality traits, was used for genetic mapping. ‘Capitola’ was resistant to the C. acutatum pathogenicity group 1 (pg1) and to P. cactorum while ‘CF1116’ was susceptible to C. acutatum and moderately susceptible to P. cactorum. Fruit quality was evaluated on a total of 34 traits, including developmental and fruit aspect related traits, texture related traits, fruit acidity, sugars, ascorbate and amino acid concentrations. Most of the traits except the amino acid concentrations were evaluated during two successive years. Disease responses to C. acutatum (pg2) and P. cactorum were evaluated using a scale from 0 (no observed symptom) to 5 (dead plant) in two successive independent experiments. Data were analysed for putative QTLs using MapQTL. For the fruit quality traits, a total of 22 significant QTLs were detected by simple interval mapping (LOD>3.0) in the first year of analyses and 17 were detected in the second year. Only two QTLs could be detected in both years. The percentages of phenotypic variance explained by each QTL ranged from 6.5% to 16.0%. For resistances, a total of nine QTLs was detected (LOD>2.0), 4 for resistance to C acutatum and 5 for resistance to P. cactorum with the percentage of variation explained by a QTL ranging from 6.5 to 12.2%. No QTL for the P. cactorum resistance overlapped the QTLs for the C acutatum resistance.
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| 19. |
- Lerceteau-Köhler, Estelle, et al.
(author)
-
QTL analysis for fruit quality traits in octoploid strawberry (Fragaria x ananassa)
- 2004
-
In: PROCEEDINGS OF THE XITH EUCARPIA SYMPOSIUM ON FRUIT BREEDING AND GENETICS, VOLS 1 AND 2. - : INT SOC HORTICULTURAL SCIENCE. ; , s. 331-335
-
Conference paper (peer-reviewed)abstract
- Mapping of quantitative trait loci (QTL) controlling components of strawberry (Fragaria x ananassa Duch., 2n=8x=56) fruit quality can be used to provide a better understanding of their genetic control, and to develop marker assisted selection for breeders. For this purpose, a segregating population of 213 individuals of a cross between ‘Capitola’ and CF1116, two genotypes with many contrasting fruit quality traits, was used for genetic mapping. A total of 34 traits involved in fruit quality were evaluated, including developmental and fruit aspect related traits, texture related traits, fruit acidity, sugar and ascorbate concentrations. Amino acid concentrations were quantified using one-dimensional proton NMR spectroscopy. Most of the traits except the amino acid concentrations were evaluated during two successive years. A total of 22 significant QTLs were detected by simple interval mapping (LOD > 3.0) in year 1, four on the female map and 18 on the male map, whereas 17 were detected in year 2, ten on the female map and seven on the male map. Only two QTLs could be detected in both years. When removing the year effect, 22 QTLs were observed, eight on the female and 14 on the male map. The percentages of phenotypic variance explained by each QTL ranged from 6.5% to 16.0%.
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| 20. |
- Lerceteau-Köhler, Estelle, et al.
(author)
-
The use of molecular markers for durable resistance breeding in the cultivated strawberry (Fragaria x ananassa)
- 2002
-
In: PROCEEDINGS OF THE FOURTH INTERNATIONAL STRAWBERRY SYMPOSIUM, VOLS 1 AND 2. - : INTERNATIONAL SOCIETY HORTICULTURAL SCIENCE. ; , s. 615-618
-
Conference paper (peer-reviewed)abstract
- In France, particularly in the southwestern area, most damage to the cultivated strawberry is anthracnose, caused by Colletotrichum acutatum. Anthracnose is a polycyclic disease for which no satisfactory disease control method has been developed. Therefore, the objective of our project is to construct durable resistance by combining the different genetic components of resistance to lower both the level of damage and the use of chemicals. Genetic components will be selected by using molecular markers linked to these loci. For monogenic resistance to the pathogenicity group 2 of C. acutatum, bulk segregant analysis (BSA) combined with the AFLP markers has been developed. Four markers were found linked to the dominant gene with a recombination percentage ranging from 0 to 13.9%. For complex resistance to the pathogenicity group 1 of C. acutatum, a linkage map has been constructed in order to detect putative QTLs associated with this complex resistance. The female map was comprised of 31 SDRF (Single Dose Restriction Fragment) markers assigned to 11 linkage groups giving a total size of 392.9 cM. On the male map, 52 SDRF markers mapped on 17 linkage groups giving a total size of 406.9 cM. The work is being continued with the addition of more markers on the maps.
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| 21. |
- Yin, T M, et al.
(author)
-
Nearly complete genetic maps of Pinus sylvestris L. (Scots pine) constructed by AFLP marker analysis in a full-sib family
- 2003
-
In: Theoretical and Applied Genetics. - : SPRINGER. - 0040-5752 .- 1432-2242. ; 106:6, s. 1075-1083
-
Journal article (peer-reviewed)abstract
- We have constructed nearly complete linkage maps of Pinus sylvestris (L.) using AFLP markers based on a two-way pseudo-testcross strategy in a full-sib family founded in an advanced breeding program. With 39 primer combinations, a total of 737 markers (320 from the mother and 417 froth the father) segregated in a 1:1 ratio, corresponding to DNA polymorphism: heterozygous in one parent and null in the other. In the maternal parent, 188 framework markers were mapped in 12 linkage groups, equivalent to the Pinus haploid chromosome number, with a total coverage of 1,695.5 cM. In the paternal parent, 245 framework markers established a map with 15 linkage groups, spanning a genome length of 1,718.5 cM. The estimated total map length was (L) over cap (F) = 1, 681 cM for the female and (L) over cap (M) = 1, 645 cM for the male using a modified method-of-moment estimator. Combining these values with those estimated from the observed map lengths in both parents, we estimated the genome length in Scots pine to be between 1,600 and 2,100 cM. Our genome coverage was estimated to be more than 98% with a framework marker interval of 20 cM for both parents. Most of the female and male linkage groups were associated through the analysis of the intercross markers.
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| 22. |
- Landström, K, et al.
(author)
-
Competitive protein adsorption between ß-casein and ß-lactoglobulin during spray-drying: effect of calcium induced association
- 2003
-
In: Food Hydrocolloids. - : Fairleigh Dickinson University Press. - 0268-005X .- 1873-7137. ; 17, s. 103-116
-
Journal article (peer-reviewed)abstract
- Competitive adsorption between ß-casein and ß-lactoglobulin (ß-Lg) during spray-drying was studied by the new surface sensitive technique using fluorescence quenching of pyrene labelled protein at the powder surface. The difference in competitiveness of -casein when present as monomers and as associated into micellar like structures were studied. Results were compared with the adsorption of single proteins at the powder surface. The adsorption of monomeric ß-casein alone gave an apparent surface load of ≈1 mg/m2 at a protein concentration of 0.3% dry weight and then remained constant with an increasing protein concentration. In the presence of Ca2+, associated ß-casein gave a lower affinity adsorption than monomeric ß-casein and did not reach a plateau value, instead it continued to increase with an increasing protein concentration. ß-Lg showed a low-affinity adsorption during spray-drying compared to monomeric ß-casein, although not as low as associated ß-casein. Competitive adsorption between monomeric ß-casein and ß-Lg resulted in a higher apparent surface load of ß-casein than ß-Lg at both protein concentrations studied (total 0.3 and 3.3% dry weight). However, in an associated form ß-casein was less competitive than ß-Lg. At a low bulk protein concentration (0.3% dry weight) ß-Lg dominated the powder surface, whereas at a higher concentration (3.3% dry weight) there was little difference between the proteins. The results indicate that the competitiveness of a protein during spray-drying is highly influenced by the ability of the protein to attach and rearrange at the droplet's air–water interface during the spray-drying process
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| 23. |
- Andersson, Mats, et al.
(author)
-
Toward an enzyme-based oxygen scavenging laminate. Influence of industrial lamination conditions on the performance of glucose oxidase
- 2002
-
In: Biotechnology and Bioengineering. - : Wiley. - 1097-0290 .- 0006-3592. ; 79:1, s. 37-42
-
Journal article (peer-reviewed)abstract
- The laminate consisted of several polymer layers, aluminium, and one cellulose-based layer containing the active enzymatic system (e.g., glucose oxidase, catalase, glucose, and CaCO3). During the industrial lamination process, the enzyme layer was exposed to three temperature spikes up to 325degreesC without significant enzyme inactivation. Ninety-seven percent of the glucose oxidase activity still remained after the lamination process. The best laminate had an oxygen absorbing capacity of 7.6 +/- 1.0 L/m(2). A reference that was not laminated expressed a corresponding oxygen absorbing capacity of 7.1 +/- 0.8 L/m(2).
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| 24. |
- Blixt, Y., et al.
(author)
-
Interlaboratory random amplified polymorphic DNA typing of Yersinia enterocolitica and Y. enterocolitica-like bacteria
- 2003
-
In: International Journal of Food Microbiology. - 0168-1605 .- 1879-3460. ; 83:1, s. 15-26
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Journal article (peer-reviewed)abstract
- A random amplified polymorphic DNA (RAPD) protocol was developed for interlaboratory use to discriminate food-borne Yersinia enterocolitica O:3 from other serogroups of Y. enterocolitica and from Y. enterocolitica-like species. Factors that were studied regarding the RAPD performance were choice of primers and concentration of PCR reagents (template DNA, MgCl 2, primer and Taq DNA polymerase). A factorial design experiment was performed to identify the optimal concentrations of the PCR reagents. The experiment showed that the concentration of the PCR reagents tested significantly affected the number of distinct RAPD products. The RAPD protocol developed was evaluated regarding its discrimination ability using 70 different Yersinia strains. Cluster analysis of the RAPD patterns obtained revealed three main groups representing (i) Y. pseudotuberculosis, (ii) Y. enterocolitica and (iii) Y. kristensenii, Y. frederiksenii, Y. intermedia and Y. ruckeri. Within the Y. enterocolitica group, the European serovar (O:3) and the North American serovar (O:8) could be clearly separated from each other. All Y. enterocolitica O:3 strains were found in one cluster which could be further divided into two subclusters, representing the geographical origin of the isolates. Thus, one of the subclusters contained Y. enterocolitica O:3 strains originating from Sweden, Finland and Norway, while Danish and English O:3 strains were found in another subcluster together with O:9 and O:5,27 strains. The repeatability (intralaboratory) and reproducibility (interlaboratory) of the RAPD protocol were tested using 15 Yersinia strains representing different RAPD patterns. The intralaboratory and the interlaboratory studies gave similarity coefficients of the same magnitude (generally >70%) for the individual strains. In the present study, it was shown that interreproducible RAPD results could be achieved by appropriate optimisation of the RAPD protocol. Furthermore, the study reflects the heterogeneous genetic diversity of the Y. enterocolitica species. © 2002 Elsevier Science B.V. All rights reserved.
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| 25. |
- Dahlenborg, Maria, et al.
(author)
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Prevalence of Clostridium botulinum types B, E, and F in faecal samples from Swedish cattle.
- 2003
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In: International Journal of Food Microbiology. - 0168-1605 .- 1879-3460. ; 82:2, s. 105-110
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Journal article (peer-reviewed)abstract
- Faeces were collected from 60 cows at three slaughterhouses situated in southern and central Sweden. The faecal samples were collected during two sampling periods over the year, summer and winter. All samples were analysed for the presence of Clostridium botulinum spores, according to a combined selection and enrichment PCR procedure. One PCR assay was specific for part of the type B neurotoxin gene, while the other assay was specific for both type E and F neurotoxin genes. The prevalence of C. botulinum in Swedish cattle was established to be 73% for non-proteolytic type B and less than 5% for types E and F. Twenty-eight (64%) of the positive faecal samples had a spore load of less than 4 spores/g. Statistical analysis (ANOVA) showed that seasonal variation (summer and winter) had a significant effect on the prevalence of C. botulinum type B in cattle, whereas the effect of geographical location of rearing of the cattle (southern and central Sweden) was less significant.
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| 26. |
- Knutsson, Rickard, et al.
(author)
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Evaluation of selective enrichment PCR procedures for Yersinia enterocolitica.
- 2002
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In: International Journal of Food Microbiology. - 0168-1605 .- 1879-3460. ; 73:1, s. 35-46
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Journal article (peer-reviewed)abstract
- Four enrichment PCR protocols for detecting unlysed cells of pathogenic Yersinia enterocolitica were studied. First, the probability of detecting Y. enterocolitica cells of known concentrations by a multiplex PCR assay was determined, and it was found to follow a logistic regression model. From this model, the probability of detecting Y enterocolitica at a specific concentration could be estimated; for example, the detection probability of 10(4) CFU/ml was estimated to be 85.4%. The protocols were evaluated on enrichment cultures inoculated with 10(2) CFU/ml Y. enterocolitica and 10(2)-10(6) CFU/ml of a defined background flora. For each protocol, the time for sample withdrawal and the presence of background flora were studied with respect to PCR detection. The optimal point in time of sample withdrawal was found to be different for each protocol employed. Early detection was favoured by concentrating the target cells, and the most rapid PCR detection of Y. enterocolitica was achieved with enrichment in Yersinia-PCR-compatible-enrichment (YPCE) medium for 3 h at 25 degrees C, followed by a centrifugation prior to PCR analysis. For detection of Y. enterocolitica in the presence of high concentrations (10(6) CFU/ml) of background flora, a long incubation time followed by density centrifugation and a dilution step was most successful. The protocol that gave the most reliable PCR detection in the presence of 10(6) CFU/ml background flora included 24 h incubation in Yersinia-selective-enrichment (YSE) broth at 25 degrees C, followed by Percoll density centrifugation, and a 100 times dilution prior to PCR analysis.
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