Indiviididevahelised erinevused rottide afektiivses käitumises: neurokeemilised uuringud

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Erinevate neurokeemiliste, näiteks monoamiinsete, süsteemide normaalse funktsioneerimise tasakaalu muutumine võib viia mitmete meeleolu- ja sõltuvushäirete tekkimiseni. Depressiooniga seotud häirete uurimisel kasutatakse sageli uudistaval käitumisel põhinevaid teste. Lisaks on leitud, et nii uudistavad kui ka sõltuvusega seotud käitumise regulatsioonis omavad rolli just monoamiinsed neurotransmitterid, mille süsteemide mõjutamine toob kaasa ka erinevused loomade käitumises. Eelnevalt oleme leidnud, et uudiskasti meetodil määratud indiviididevahelised erinevused uudistamisaktiivsuses on ajas püsivad ning neid indiviididevahelisi erinevusi on ka neurotransmitterite regulatsioonis. Mikrodialüüsi katsed näitasid, et serotonergiline süsteem on eri ajupiirkondades erinevalt reguleeritud. Väheuudistavatel (LE) rottidel on frontaalkoores kõrgemad rakuvälised serotoniini sisaldused kõrgemad peale serotoniini transpordi inhibeerimist tsitalopraamiga. Vastupidised tulemused ilmnesid hipokampuses, kus kõrgemad serotoniini tasemed olid just paljuuudistavatel (HE) rottidel. Kuna hiljutised uuringud on näidanud, et monoamiinide kõrval võib ka glutamaadi süsteemil olla oluline roll depressiooni kujunemisel, siis uuriti ka glutamaadi sisaldusi erineva uudistamisaktiivsusega rottidel. Leiti, et võrreldes väheuudistavate rottidega, on paljuuudistavatel rottidel kõrgemad glutamaadi sisaldused peale glutamaadi transpordi inhibeerimist juttkehas, kuid mitte hipokampuses. Sellest järeldub, et indiviididevahelised erinevused uudistavas käitumises võivad olla seotud lisaks serotonergilisele ka glutamatergilise närviülekandega. Uudistav käitumine on suurel määral sõltuv sinava tuuma (locus coeruleus) noradrenaliini projektsioonidest. Rotid, kellel on antud süsteemi kahjustus, käituvad uudiskasti testis nagu LE-fenotüüp, mida on seostatud madalama dopaminergilise neurotransmissiooni efektiivsusega. uuriti, kas sinava tuuma projektsioonid on olulised dopaminergilisele süsteemile toimivatele psühhostimulantide efektidele. Leiti, et ulatuslik sinava tuuma projektsioonide kahjustus närvitoksiiniga DSP-4 [N-(2-kloroetüül-N-etüül-2-bromobensüülamiin] vähendas psühhostimulandi kokaiini poolt stimuleeritud kohaeelistust ja liikumisaktiivsust. Kuna elusündmused varajases elustaadiumis võivad samuti omada mõju neurokeemilistele süsteemidele, siis uuriti kas alkoholist tingitud efektid monoamiini süsteemidele on sõltuvad varajasest elukeskkonnast. Leiti, et erinevused serotonergilises süsteemis olid just alkoholi eelistavatel loomadel, kes olid noores eas emast kõige kauem eraldatud. Siit järeldub, et varajases eas toimuvatel sündmustel on oluline mõju alkoholi tarbimisele ning serotonergilise süsteemi toimimisele. Leiti, et nendel alkoholi eelistavatel loomadel, kes olid noores east emast kaua eraldatud, olid serotoniini tasemed madalamad just mandelkehas, mida seostakse enim just sõltuvushäirete tekkimisega. Siit järeldub, et varajases eas toimuvatel sündmustel on oluline mõju alkoholi tarbimisele ning serotonergilise süsteemi toimimisele. Viimastel aastatel on negatiivsete afektiivsete seisundite kõrval hakatud rohkem uurima positiivse emotsionaalsuse võimaliku rolli üle depressiooni kujunemisel. Positiivset emotsionaalsust on võimalik uurida mõõtes rottide ultraheli-häälitsusi. Nüüdseks on leitud, et rottidel on püsivad indiviidivahelised erinevused nende 50-kHz ultraheli häälitsustes, mida seostatakse rottide positiivse emotsionaalsusega. Antud töös leiti, et stressi tingimustes on vähepiuksuvatel rottidel kõrgemad serotoniini tasemed peale serotoniini transpordi tagasihaarde inhibeerimist. Lisaks on samadel rottidel kõrgemad kortikosterooni tasemed. Antud tulemustest järeldub, et madalama positiivse emotsionaalsusega rotid on stressile vastuvõtlikumad. Võttesse arvesse neurotransmitterite erinevat regulatsiooni rottide käitumise kujunemisel võib jõuda depressiooniga seotud seisundite uudsete farmakoloogiliste ravimeetoditeni.Inter-individual differences, that are probably caused by variations in the regulation of neurochemical pathways, exist between organisms, and are likely to be significant in the pathogenesis of affective disorders. Depression is a highly prevalent psychopathological condition. In order to investigate depression the tests based on exploratory behaviour of rats are mostly used. Studies in the present dissertation indicate that rats with different exploratory phenotype differ, in addition to catecholaminergic mechanisms, also with regard to regulation of serotonergic and glutamatergic systems. Serotonergic neurotransmission in hippocampus and prefrontal cortex was found to be regionally differentially regulated in low exploring (LE) and high exploring (HE) rats. In prefrontal cortex, the LE-rats had higher extracellular serotonin levels induced by citalopram and higher levels of serotonin transporter binding. In dentate gyrus, contrary, the HE-rats had higher levels of extracellular serotonin. Additionally, HE-rats had increased levels of glutamate after blockade of glutamate transporter in striatum. Exploratory behaviour is very much dependent on the function of the noradrenergic projections of the locus coeruleus. All rats with near complete denervation of these projections behave in the exploration box test like the spontaneous LE-phenotype that has been associated with less efficient dopaminergic neurotransmission. It appeared that extensive denervation of the noradrenergic projections from locus coeruleus indeed reduced the effect of cocaine-induced place preference and locomotor activation. Early life experiences may also affect neurochemical mechanisms and thereby influence the behavioural pattern later in life. Thus, the effect of maternal separation (as the early life stress) on alcohol consumption was studied. It appeared that animals that experienced long maternal separation had low serotonin levels in amygdala and responded with an increase in serotonin after ethanol intake, which is a key area in addiction processes. Predisposition to express positive affect at low levels had previously been linked to vulnerability to depression. We could confirm the higher sensitivity of the LC-rats that produce less 50-kHz vocalizations to chronic stress: they gained weight more slowly and had higher corticosterone levels measured from full blood after stress. LC-rats have also differences in serotonergic mechanisms after chronic stress was supported by the finding that stressed LC-rats had higher extracellular serotonin levels induced by citalopram in hippocampus, where serotonergic system has been known to mediate response to anxious stimuli. These findings support the notion that male rats with low 50-kHz USVs response to tickling, having lower positive emotionality, are behaviourally more vulnerable to stress. Taken together, the consideration of these neurobiological differences between individuals could lead to novel approaches to more personalized medical treatment of depression-related states

pH mõju nitritlämmastiku akumulatsioonile magedaveelises denitrifikatsioonisüsteemis

Denitrifikatsioon on bioloogiline lämmastikuärastusprotsess, mis teatud tingimustes kulgeb mittetäielikult, tekitades nitriti akumulatsiooni. Töös uuriti pH mõju antud nähtusele, teostati annuskatsed (kuni 6 tundi) ning pilootkatsed (48 päeva). Annuskatsetes täheldati pH iseeneslikku tõusu väärtuse 9,5 poole, millega kaasnes ka oluline nitriti akumulatsiooni tõus. Akumulatsioon võib tuleneda nitriti reduktaasi osalisest inhibeeritusest kõrge pH väärtuse poolt, mille tõttu osa toodetud nitritist jääb keskkonda alles. Pilootkatsetes saavutati katse alguses sarnased tulemused, kuid biomassi kohanedes kõrge pH väärtusega nitriti akumulatsioon vähenes. Nitriti akumulatsiooni kasutamiseks tehnoloogilise protsessina soovitatakse biomassi pidevalt reaktoris vahetada, et vältida selle kohastumist tugevalt aluselise keskkonnaga

A parameterization of flow separation over subaqueous dunes

Flow separation plays a key role in the development of dunes, and modeling the complicated flow behavior inside the flow separation zone requires much computational effort. To make a first step toward modeling dune development at reasonable temporal and spatial scales, a parameterization of the shape of the flow separation zone over two-dimensional dunes is proposed herein, in order to avoid modeling the complex flow inside the flow separation zone. Flow separation behind dunes, with an angle-of-repose slip face, is characterized by a large circulating leeside eddy, where a separation streamline forms the upper boundary of the recirculating eddy. Experimental data of turbulent flow over two-dimensional subaqueous bed forms are used to parameterize this separation streamline. The bed forms have various heights and height to length ratios, and a wide range of flow conditions is analyzed. This paper shows that the shape of the flow separation zone can be approximated by a third-order polynomial as a function of the distance away from the flow separation point. The coefficients of the polynomial can be estimated, independent of flow conditions, on the basis of bed form shape at the flow separation point and a constant angle of the separation streamline at the flow reattachment point. \ud \u

SMOOTH TEMPERATURE DECREASING FOR NITROGEN REMOVAL IN COLD (9-15° C) ANAMMOX BIOFILM REACTOR TESTS

For N-rich wastewater treatment the anaerobic ammonium oxidation (anammox) and nitritation-anammox (deammonification) processes are widely used. In a deammonification moving bed biofilm reactor (MBBR) a maximum total nitrogen removal rate (TNRR) of 1.5 g N m-2d-1(0.6 kg N m-3d-1) was achieved. During biofilm cultivation, temperature was gradually lowered by 0.5° C per week, and a similar TNRR was sustained at 15° C. qPCR analysis showed an increase in Candidatus Brocadia quantities from 5×103 to 1×107 anammox gene copies g-1 TSS despite temperature lowered to 15° C. Fluctuations in TNRR were rather related to changes in influent NH4+ concentration. To study the short-term effect of temperature on the TNRR, a series of batch-scale experiments were performed which showed sufficient TNRRs even at 9-15° C (4.3-5.4 mg N L-1 h-1, respectively) with anammox temperature constants ranging 1.3-1.6. After biomass was adapted to 15° C, the decrease in TNRR in batch tests at 9° C was lower (15-20%) than for biomass adapted to 17-18° C. Our experiments show that a biofilm of a deammonification reactor adapted to 15° C successfully tolerates shortterm cold shocks down to 9° C retaining a high TNRR

Dynamical models for sand ripples beneath surface waves

We introduce order parameter models for describing the dynamics of sand ripple patterns under oscillatory flow. A crucial ingredient of these models is the mass transport between adjacent ripples, which we obtain from detailed numerical simulations for a range of ripple sizes. Using this mass transport function, our models predict the existence of a stable band of wavenumbers limited by secondary instabilities. Small ripples coarsen in our models and this process leads to a sharply selected final wavenumber, in agreement with experimental observations.Comment: 9 pages. Shortened version of previous submissio

Wave-formed sediment ripples: Transient analysis of ripple spectral development

A new method has been developed that models the changes a wave-formed rippled sediment bed undergoes as it is actively evolving between two given equilibrium states due to a change in surface wave conditions. The transient analysis of rippled beds has received very little attention within the literature. Dynamic changes within ripple parameters have implications for the estimation of flow dissipation and sediment transport by changing the bottom roughness height. The method uses the spectral density function of the rippled bed and is based on a series of ripple growth and ripple transition experimental tests. The ripple evolution model was developed from the well-known Logistic Growth Law. Fitting the general solution of the logistic nonlinear differential equation to the experimental data enabled the evolution rate of the bed to be determined for each experimental test. It was concluded that there was no difference between the evolution rate determined from the ripple growth tests and the ripple transition tests. This indicated that the two types of growth are special cases of the same evolution processes, which is adequately modeled by the logistic growth equation. A functional dependence was established between the ripple evolution rate and the Shields parameter. This allows the evolution rate to be estimated from flow and sediment properties. The estimation of the rate at which rippled sediment beds evolve under a variable sea state has the potential to lead to significant improvements to the way ripple transition and hence bottom roughness is approximated in coastal wave models.Joseph P. Davis, David J. Walker, Murray Townsend, Ian R. Youn

Practical sand transport formula for non-breaking waves and currents

Open Access funded by Engineering and Physical Sciences Research Council Under a Creative Commons license Acknowledgements This work is part of the SANTOSS project (‘SANd Transport in OScillatory flows in the Sheet-flow regime’) funded by the UK's EPSRC (GR/T28089/01) and STW in The Netherlands (TCB.6586). JW acknowledges Deltares strategic research funding under project number 1202359.09. Richard Soulsby is gratefully acknowledged for valuable discussions and feedback on the formula during the SANTOSS project.Peer reviewedPostprin

Effect of roughness formulation on the performance of a coupled wave, hydrodynamic, and sediment transport model

This paper is not subject to U.S. copyright. The definitive version was published in Ocean Modelling 33 (2010): 299-313, doi:10.1016/j.ocemod.2010.03.003.A variety of algorithms are available for parameterizing the hydrodynamic bottom roughness associated with grain size, saltation, bedforms, and wave–current interaction in coastal ocean models. These parameterizations give rise to spatially and temporally variable bottom-drag coefficients that ostensibly provide better representations of physical processes than uniform and constant coefficients. However, few studies have been performed to determine whether improved representation of these variable bottom roughness components translates into measurable improvements in model skill. We test the hypothesis that improved representation of variable bottom roughness improves performance with respect to near-bed circulation, bottom stresses, or turbulence dissipation. The inner shelf south of Martha’s Vineyard, Massachusetts, is the site of sorted grain-size features which exhibit sharp alongshore variations in grain size and ripple geometry over gentle bathymetric relief; this area provides a suitable testing ground for roughness parameterizations. We first establish the skill of a nested regional model for currents, waves, stresses, and turbulent quantities using a uniform and constant roughness; we then gauge model skill with various parameterization of roughness, which account for the influence of the wave-boundary layer, grain size, saltation, and rippled bedforms. We find that commonly used representations of ripple-induced roughness, when combined with a wave–current interaction routine, do not significantly improve skill for circulation, and significantly decrease skill with respect to stresses and turbulence dissipation. Ripple orientation with respect to dominant currents and ripple shape may be responsible for complicating a straightforward estimate of the roughness contribution from ripples. In addition, sediment-induced stratification may be responsible for lower stresses than predicted by the wave–current interaction model.Funding was provided through the Office of Naval Research Ripples DRI and U.S. Geological Survey Coastal and Marine Geology Program