A matter of taste : genetic and environmental influences on responses to sweetness

Diet is a major player in the maintenance of health and onset of many diseases of public health importance. The food choice is known to be largely influenced by sensory preferences. However, in many cases it is unclear whether these preferences and dietary behaviors are innate or acquired. The aim of this thesis work was to study the extent to which the individual differences in dietary responses, especially in liking for sweet taste, are influenced by genetic factors. Several traits measuring the responses to sweetness and other dietary variables were applied in four studies: in British (TwinsUK) and Finnish (FinnTwin12 and FinnTwin16) twin studies and in a Finnish migraine family study. All the subjects were adults and they participated in chemosensory measurements (taste and smell tests) and filled in food behavior questionnaires. Further, it was studied, whether the correlations among the variables are mediated by genetic or environmental factors and where in the genome the genes influencing the heritable traits are located. A study of young adult Finnish twins (FinnTwin16, n=4388) revealed that around 40% of the food use is attributable to genetic factors and that the common, childhood environment does not affect the food use even shortly after moving from the parents home. Both the family study (n=146) and the twin studies (British twins, n=663) showed that around half of the variation in the liking for sweetness is inherited. The same result was obtained both by the chemosensory measurements (heritability 41-49%) and the questionnaire variables (heritability 31-54%). By contrast, the intensity perception of sweetness or the responses to saltiness were not influenced by genetic factors. Further, a locus influencing the use-frequency of sweet foods was identified on chromosome 16p. A closer examination of the relationships among the variables based on 663 British twins revealed that several genetic and environmental correlations exist among the different measures of liking for sweetness. However, these correlations were not very strong (range 0.06-0.55) implying that the instruments used measure slightly different aspects of the phenomenon. In addition, the assessment of the associations among responses to fatty foods, dieting behaviors, and body mass index in twin populations (TwinsUK n=1027 and FinnTwin12 n=299) showed that the dieting behaviors (cognitive restraint, uncontrolled eating, and emotional eating) mediate the relationship between obesity and diet. In conclusion, the work increased the understanding of the background variables of human eating behavior. Genetic effects were shown to underlie the variation of many dietary traits, such as liking for sweet taste, use of sweet foods, and dieting behaviors. However, the responses to salty taste were shown to be mainly determined by environmental factors and thus should more easily be modifiable by dietary education, exposure, and learning than sweet taste preferences. Although additional studies are needed to characterize the genetic element located on chromosome 16 that influences the use-frequency of sweet foods, the results underline the importance of inherited factors on human eating behavior.

Prolamin degradation in sourdoughs

This thesis examines protein behaviours that occur during cereal fermentations. The focus is on the prolamin degradation in sourdoughs. The thesis also looks at what happens to the oat globulins during an oat bran acidification process. The cereal prolamins are unique proteins in many respects. The wheat prolamins (glutenins and gliadins) are responsible for the formation of the gluten that provides the viscoelastic properties to wheat doughs whereas the rye prolamins (secalins) are unable to develop gluten-like structures. In addition, many baking technological features, such as flavour, shelf-life and dough properties are affected by the protein degradation that might occur during processing. On the other hand, the prolamins contain protein structures that are harmful to gluten sensitive people. It is thus evident that the degradation of the prolamins in sourdough processes may be approached from various aspects. This thesis describes some of these approaches. Four different cereal fermentations were carried out. Wheat sourdough (WSD) and rye sourdough (RSD) fermentations represented traditional sourdoughs. A germinated-wheat sourdough (GWSD) was a novel sourdough type that was prepared using germinated wheat grains that had high and diverse proteolytic activities. The oat bran fermentation (OBF) represented a fermentation system that lacked functional cereal proteases. The high molecular weight glutenins and rye secalins were degraded during the WSD and RSD fermentations, respectively. It was noteworthy that in WSD only a very limited degradation of the gliadins occurred. The gliadins were, however, hydrolysed very extensively during the GWSD fermentation. No protein degradation was observable in the OBF system. Instead the acidification altered the solubility of the oat globulins and this finally led to their aggregation. This thesis confirms that the endogenous proteases of cereals hydrolyse cereal prolamins in sourdoughs. The thesis also shows that the proteolytic activity of the used cereal raw material determines the extent of proteolysis that occurs in sourdough. This means that bakers may adjust the protein degradation in their sourdoughs by selecting the raw material based on its proteolytic activity. The thesis also demonstrates that by using germinated grains, with high and diverse proteolytic activity in sourdough preparations, the prolamins can be extensively degraded. Whether such highly proteolytic food technology could be used to manufacture new gluten-free cereal-based products for gluten sensitive people remains to be solved.

A review of the application of molecular genetics for fisheries management and conservation of sharks and rays

Since the first investigation 25 years ago, the application of genetic tools to address ecological and evolutionary questions in elasmobranch studies has greatly expanded. Major developments in genetic theory as well as in the availability, cost effectiveness and resolution of genetic markers were instrumental for particularly rapid progress over the last 10 years. Genetic studies of elasmobranchs are of direct importance and have application to fisheries management and conservation issues such as the definition of management units and identification of species from fins. In the future, increased application of the most recent and emerging technologies will enable accelerated genetic data production and the development of new markers at reduced costs, paving the way for a paradigm shift from gene to genome-scale research, and more focus on adaptive rather than just neutral variation. Current literature is reviewed in six fields of elasmobranch molecular genetics relevant to fisheries and conservation management (species identification, phylogeography, philopatry, genetic effective population size, molecular evolutionary rate and emerging methods). Where possible, examples from the Indo-Pacific region, which has been underrepresented in previous reviews, are emphasized within a global perspective. (C) 2012 The Authors Journal of Fish Biology (C) 2012 The Fisheries Society of the British Isles

Molecular phylogeny of Archaea in boreal forest soil, freshwater and temperate estuarine sediment

Suurin osa luonnossa havaitsemistamme mikrobeista on sellaisia, joita emme edelleenkään osaa kasvattaa laboratorio-oloissa, vaikka tietomme mikrobien monimuotoisuudesta paranevat koko ajan. Luonnontilaisen mikrobieliöstön kokoonpano eri ympäristöissä on paljolti epäselvä ja ymmärrämme vielä hyvin puutteellisesti mikrobien ekologiaa ja niiden rooleja eliöyhteisöissä. Nykyaikaiset molekulaariset tutkimusmenetelmät auttavat selvittämään mikrobien monimuotoisuutta kokonaisvaltaisesti ja nopeasti. Ympäristöstä kemiallisesti puhdistetut ribosomaalista RNA:ta koodaavat geenit edustavat periaatteessa kaikkia eliöyhteisön geneettisesti toisistaan poikkeavia eliöitä. Niistä voidaan valikoida halutut genomit jatkotutkimuksia varten. Uusien menetelmien käyttö on tuonut esiin sen merkittävän seikan, että "tavanomaisten" elinympäristöjen eliöyhteisöihin kuuluu suuri joukko entuudestaan tuntemattomia arkkieliöitä. Aiemmin kuviteltiin, että arkkieliöt asuttavat vain sellaisia "epätavallisia" tai "äärimmäisiä" elinympäristöjä, joita luonnehtii joku seuraavista ominaisuuksista: hyvin korkea lämpötila, korkea suolapitoisuus, korkea happamuus tai emäksisyys, hapettomuus. Tutkijat ovat viimeisen noin kymmenen vuoden aikana osoittaneet, että arkkieliöt asuttavat hyvin monenlaisia kylmän ja lauhkean vyöhykkeen ympäristöjä, yhtä hyvin maaperää kuin suolaisen ja makean veden pohjaa tai pintakerroksia. Nämä löydöt ovat avanneet uuden alun arkkieliöiden tutkimukselle, erityisesti sen selvittämiselle, mitkä ovat niiden fysiologiset ja ekologiset roolit monimuotoisissa mikrobiyhteisöissä. Tämä väitöskirja kuvaa entuudestaan tuntemattomien arkkieliöiden löytymistä havumetsävyöhykkeen metsämaasta. Arkkieliöitä löytyi myös lauhkean vyöhykkeen vuorovesialueelta, murtoveden huuhtelemasta pohjasta. Nämä löydöt ovat perustavalaatuisia vuorovesialueen eliöyhteisöjen ymmärtämiseksi. Suomalaisen metsäjärven vedestä määritettiin molempien arkkieliöiden pääryhmien - tieteellisiltä nimiltään Crenarchaeota ja Euryarchaeota - edustajia. Euryarchaeota-ryhmän edustajia voitiin havainnoida myös fluoresenssi-mikroskopoinnilla. Löydöt viittaavat siihen, että arkkieliöillä on oma biogeokemiallinen roolinsa makeanveden ravintoketjujen hiilen käytössä. Tässä työssä määritetyt uudet arkkieliöiden genomien nukleotidisekvenssit on toimitettu ARB-tietokantaan, jonka kasvava vertailuaineisto edelleen parantaa uusien arkkieliösekvenssien analyysiä ja auttaa hybridisaatiokoetinten ja polymeraasiketjureaktioalukkeiden suunnittelussa ja arvioinnissa. Tässä väitöskirjassa esitellyt tulokset yhdessä lukuisien vesi-, maaperä- ja muiden ympäristöjen arkkieliöitä käsittelevien julkaisujen kanssa osoittavat, että arkkieliöt asuttavat monia erilaisia elinympäristöjä ja että ne ovat ekologisesti paljon menestyneempiä, kuin tieteenalalla on kuviteltu. Voimme olettaa, että heti kun joitain näistä eliöistä onnistutaan kasvattamaan ja ylläpitämään laboratorio-oloissa, niiden joukosta löydetään aivan uusia, entuudestaan tuntemattomia fysiologisia fenotyyppejä, jotka avaavat mielenkiintoisia näkymiä aineenvaihdunnan ja perinnöllisten ominaisuuksien tutkimukselle.

Molecular and crystal structure of deoxyguanosine 5'-phosphate

RECENT crystallographic studies of the dinucleosides ApU (ref. 1) and GpC (ref. 2) have given experimental proof for the base pairing arrangement proposed by Watson and Crick for the DNA double helix3. Another striking feature of this structure relates to the torsional angle about the C5'-C4' bond in the phosphate−sugar backbone chain. In the Crick and Watson model4, this conformation is gauche−trans (GT). Crystal structures of 5'-nucleotides, dinucleosides and dinucleotides so far studied, however, have shown only the gauche−gauche (GG) conformation about this bond. The GG conformer is also the only one found in the refined models of the proposed structure of the double helical nucleic acids and polynucleotides5−7. The only nucleotide with a GT conformation is 6-azauridine-5'-phosphate8 which is not a normal monomer unit of nucleic acids. It is also reported that 5'-dGMP assumes preferentially GT conformation in solution9.

Sequence variation in the putative effector gene SIX8 facilitates molecular differentiation of Fusarium oxysporum f. sp. cubense

Fusarium oxysporum f. sp. cubense (Foc), causal agent of fusarium wilt of banana, is among the most destructive pathogens of banana and plantain. The development of a molecular diagnostic capable of reliably distinguishing between the various races of the pathogen is of key importance to disease management. However, attempts to distinguish isolates using the standard molecular loci typically used for fungal phylogenetics have been complicated by a poor correlation between phylogeny and pathogenicity. Among the available alternative loci are several putative effector genes, known as SIX genes, which have been successfully used to differentiate the three races of F. oxysporum f. sp. lycopersici. In this study, an international collection of Foc isolates was screened for the presence of the putative effector SIX8. Using a PCR and sequencing approach, variation in Foc-SIX8 was identified which allowed race 4 to be differentiated from race 1 and 2 isolates, and tropical and subtropical race 4 isolates to be distinguished from one another.

Complete cytogenetic response and major molecular response as surrogate outcomes for overall survival in first-line treatment of chronic myelogenous leukemia: A case study for technology appraisal on the basis of surrogate outcomes evidence

Objectives In 2012, the National Institute for Health and Care Excellence assessed dasatinib, nilotinib, and standard-dose imatinib as first-line treatment of chronic phase chronic myelogenous leukemia (CML). Licensing of these alternative treatments was based on randomized controlled trials assessing complete cytogenetic response (CCyR) and major molecular response (MMR) at 12 months as primary end points. We use this case study to illustrate the validation of CCyR and MMR as surrogate outcomes for overall survival in CML and how this evidence was used to inform National Institute for Health and Care Excellence’s recommendation on the public funding of these first-line treatments for CML. Methods We undertook a systematic review and meta-analysis to quantify the association between CCyR and MMR at 12 months and overall survival in patients with chronic phase CML. We estimated life expectancy by extrapolating long-term survival from the weighted overall survival stratified according to the achievement of CCyR and MMR. Results Five studies provided data on the observational association between CCyR or MMR and overall survival. Based on the pooled association between CCyR and MMR and overall survival, our modeling showed comparable predicted mean duration of survival (21–23 years) following first-line treatment with imatinib, dasatinib, or nilotinib. Conclusions This case study illustrates the consideration of surrogate outcome evidence in health technology assessment. Although it is often recommended that the acceptance of surrogate outcomes be based on randomized controlled trial data demonstrating an association between the treatment effect on both the surrogate outcome and the final outcome, this case study shows that policymakers may be willing to accept a lower level of evidence (i.e., observational association).

Molecular motion in plastic crystals

Abstract is not available.

Photochemical Reactions in Oriented Systems

Modification of chemical reactions through the use of constrained and/or organized media has attracted a great deal of attention recently. Results from our laboratory in this direction which include a study of photochemical reactions in solid state and in cyclodextrins are presented here. A study of solid state photochemical behavior of coumarins has provided information regarding subtler aspects of topochemical postulates of photodimerization. Results pertaining to geometrical criteria for photodimerization and "chloro" as a crystal engineering group are discussed. As a part of an attempt to correlate chemical reactivity with molecular packing in the solid state, photooxidation of diarylthioketones in the solid state has been investigated. The observed differences in the reactivity of these crystals are rationalized in terms of crystal packing. Though cyclodextrins have been extensively studied, very few photochemical reactions involving molecules complexed to cyclodextrins have been examined. In this connection, the utility of cyclodextrins in bringing about selectivity in photochemical reactions through the study of excited state behavior of olefins and aryl alkyl ketones has been demonstrated in our laboratory.

Water-ethanol mixtures by molecular dynamics and x-ray Compton scattering

Water-ethanol mixtures are commonly used in industry and house holds. However, quite surprisingly their molecular-level structure is still not completely understood. In particular, there is evidence that the local intermolecular geometries depend significantly on the concentration. The aim of this study was to gain information on the molecular-level structures of water-ethanol mixtures by two computational methods. The methods are classical molecular dynamics (MD), where the movement of molecules can be studied, and x-ray Compton scattering, in which the scattering cross section is sensitive to the electron momentum density. Firstly, the water-ethanol mixtures were studied with MD simulations, with the mixture concentration ranging from 0 to 100%. For the simulations well-established force fields were used for the water and ethanol molecules (TIP4P and OPLS-AA, respectively). Moreover, two models were used for ethanol, rigid and non-rigid. In the rigid model the intramolecular bond lengths are fixed, whereas in the non-rigid model the lengths are determined by harmonic potentials. Secondly, mixtures with three different concentrations employing both ethanol models were studied by calculating the experimentally observable x-ray quantity, the Compton profile. In the MD simulations a slight underestimation in the density was observed as compared to experiment. Furthermore, a positive excess of hydrogen bonding with water molecules and a negative one with ethanol was quantified. Also, the mixture was found more structured when the ethanol concentration was higher. Negligible differences in the results were found between the two ethanol models. In contrast, in the Compton scattering results a notable difference between the ethanol models was observed. For the rigid model the Compton profiles were similar for all the concentrations, but for the non-rigid model they were distinct. This leads to two possibilities of how the mixing occurs. Either the mixing is similar in all concentrations (as suggested by the rigid model) or the mixing changes for different concentrations (as suggested by the non-rigid model). Either way, this study shows that the choice of the force field is essential in the microscopic structure formation in the MD simulations. When the sources of uncertainty in the calculated Compton profiles were analyzed, it was found that more statistics needs to be collected to reduce the statistical uncertainty in the final results. The obtained Compton scattering results can be considered somewhat preliminary, but clearly indicative of the behaviour of the water-ethanol mixtures when the force field is modified. The next step is to collect more statistics and compare the results with experimental data to decide which ethanol model describes the mixture better. This way, valuable information on the microscopic structure of water-ethanol mixtures can be found. In addition, information on the force fields in the MD simulations and on the ability of the MD simulations to reproduce the microscopic structure of binary liquids is obtained.

On some design aspects of rotary vane pumps

A simple graphical design procedure is established for designing rotary vane vacuum pumps with capacities ranging from 20 litre/min to 500 litre/min, normally used in small laboratories. A new term called the idle angle is defined and its influence on the volumetric efficiency of some commercially available pumps is discussed.