Transfer of metabolites across the peroxisomal membrane

AbstractPeroxisomes perform a large variety of metabolic functions that require a constant flow of metabolites across the membranes of these organelles. Over the last few years it has become clear that the transport machinery of the peroxisomal membrane is a unique biological entity since it includes nonselective channels conducting small solutes side by side with transporters for ‘bulky’ solutes such as ATP. Electrophysiological experiments revealed several channel-forming activities in preparations of plant, mammalian, and yeast peroxisomes and in glycosomes of Trypanosoma brucei. The properties of the first discovered peroxisomal membrane channel – mammalian Pxmp2 protein – have also been characterized. The channels are apparently involved in the formation of peroxisomal shuttle systems and in the transmembrane transfer of various water-soluble metabolites including products of peroxisomal β-oxidation. These products are processed by a large set of peroxisomal enzymes including carnitine acyltransferases, enzymes involved in the synthesis of ketone bodies, thioesterases, and others. This review discusses recent data pertaining to solute permeability and metabolite transport systems in peroxisomal membranes and also addresses mechanisms responsible for the transfer of ATP and cofactors such as an ATP transporter and nudix hydrolases. This article is part of a Special Issue entitled: Metabolic Functions and Biogenesis of Peroxisomes in Health and Disease

Suitability of Phytosterols Alongside Fatty Acids as Chemotaxonomic Biomarkers for Phytoplankton

The composition and abundance of phytoplankton is an important factor defining ecological status of marine and freshwater ecosystems. Chemotaxonomic markers (e.g., pigments and fatty acids) are needed for monitoring changes in a phytoplankton community and to know the nutritional quality of seston for herbivorous zooplankton. Here we investigated the suitability of sterols along with fatty acids as chemotaxonomic markers using multivariate statistics, by analyzing the sterol and fatty acid composition of 10 different phytoplankton classes including altogether 37 strains isolated from freshwater lakes. We were able to detect a total of 47 fatty acids and 29 sterols in our phytoplankton samples, which both differed statistically significantly between phytoplankton classes. Due to the high variation of fatty acid composition among Cyanophyceae, taxonomical differentiation increased when Cyanophyceae were excluded from statistical analysis. Sterol composition was more heterogeneous within class than fatty acids and did not improve separation of phytoplankton classes when used alongside fatty acids. However, we conclude that sterols can provide additional information on the abundance of specific genera within a class which can be generated by using fatty acids. For example, whereas high C-16 omega-3 PUFA (polyunsaturated fatty acid) indicates the presence of Chlorophyceae, a simultaneous high amount of ergosterol could specify the presence of Chlamydomonas spp. (Chlorophyceae). Additionally, we found specific 4 alpha-methyl sterols for distinct Dinophyceae genera, suggesting that 4a-methyl sterols can potentially separate freshwater dinoflagellates from each other.Peer reviewe

Drift compensation using a multichannel slot waveguide Young interferometer

Polymeric integrated Young interferometer sensor chips utilizing a slot waveguide have demonstrated to be sensitive, to work at visible wavelengths, to be manufacturable by simple process, and to have a reduced sensitivity to temperature fluctuations. Although slot waveguide Young interferometers have these desirable features for low-cost rapid diagnostics, the sensor readout is disturbed by mechanical drifts of the sensing system. In this paper we demonstrate that mechanical drifts of the readout system can be compensated by using a multichannel slot waveguide Young interferometer having two reference waveguides and applying a drift compensation method based on the analysis of the spatial shifts of the interferogram fringes. The applicability of the drift compensation method was studied by conducting experiments with undisturbed and with mechanically disturbed setup to measure the phase changes induced by the changes of the bulk refractive index. By applying the drift compensation method, the sample induced phase change responses were extracted from up to 18 times larger measured phase changes in the disturbed experiments proving the applicability of the method with multichannel slot waveguide Young interferometers

Mikrofluidiset mallit metastaasitutkimuksessa

Tiivistelmä. Parannuksia mikrofluidisiin malleihin täytyy vielä tehdä kliinisesti pätevien tuloksien saamista varten. Mallien rakentamisessa useimmiten käytetty materiaali on PDMS. Kuitenkin PDMS:llä on tunnetusti ongelmia, joita esimerkiksi termoplastiset materiaalit voivat välttää. Vastaavasti biotulostamisen tekniikoissa on uusien biomusteiden löytäminen tarpeellista. Biotulostaminen osoittaa tällä hetkellä teknologioiden kehittyessä valtavaa lupausta syöpätutkimuksen tulevaisuudessa tarkan rakenteen valmistamisen takia elintasolla (Monjezi et al. 2021). Potilaskohtaiset mikrofluidiset mallit ovat vielä alkuvaiheissa. Monet mikrofluidiset mallit käyttävät tutkimuksissansa solulinjoja, jotka osoittavat tiedettyjä mahdollisesti tutkimukselle edullisia ominaisuuksia. Potilaskohtaiset mallit voivat mahdollistaa tulevaisuudessa mikrofluidisten mallien käytön laajasti kliinisissä olosuhteissa sekä antaa mikrofludisella metastaasitutkimukselle laajempaa näyttöä (Monjezi et al. 2021). Metastaattisen syövän hoitoa tutkiessa mikrofluidisilla malleilla on tulevaisuudessa tärkeää tutkia monen elimen vaikutusta kokonaisuuteen. Myös syövän metastaasia tutkiessa täytyy useiden elimien vaikutuksia harkita mikroympäristön muodostumisessa ja käyttäytymisessä. Metastaasitutkimus suoritetaan usein osissa mikrofluidisissa malleissa. Tulevaisuudessa tulee rakentaa metastaasimalleja, joissa koko metastaattinen kaskadi tapahtuu yhden mallin sisäisesti. Tähän vaaditaan vähintään primaarielin malli sekä sekundaari elinmalli, johon syöpäsolut metastoituvat (Graney et al. 2021). Immuunisysteemin mallintaminen syöpää tutkiessa on äärimmäisen tärkeää. Tulevaisuudessa suurempaa määrää erilaisia immuunisoluja tulisi käyttää tehdessä immuunipäteviä mikrofluidisia syöpämalleja. Immuunisolut, kuten säätelijä-T-solut, ovat jääneet monista nykyisistä malleista huomioimatta. Myös immuunipuolustuksen erot syövän kohde-elimissä täytyy huomioida. Lihavuuden aiheuttama jatkuva tulehdustila adipoosikudoksessa johtaa T-solujen uupumiseen. Vastaavia tilanteita tulee pystyä mallintamaan tuottaakseen tarkkoja immuuniterapian malleja tulevaisuudessa (Maulana et al. 2021). Mikrofluidisten mallien rooli syöpätutkimuksessa tulee luultavasti vain kasvamaan tulevaisuudessa. Mikrofluidisilla malleilla on potentiaalia tuottaa luotettavampia tuloksia korkealla toistettavuudella. Tämän saavuttamiseksi tulee kuitenkin jatkaa laitteiden parantelua sekä mikroympäristön ja kasvaimen tarkempaa mallintamista

Analysis of ground heat exchanger for a ground source heat pump : A study of an existing system to find optimal borehole length to enhance the coefficient of performance

Ground Source Heat Hump is one of the emerging technic to utilize the reservoir of geothermal energy in Europe. The crucial factor is to find the optimal length of the borehole to successfully design a heating system. The length of the borehole varies depending on the geographical area, the capacity of the heat pump and heat load of the desired building in consideration. Several methods have been theorized and validated using the experimental measurements to find the optimal length of the borehole. The most commonly used methods are American Society of Heating, Refrigeration and Air-conditioning Engineers and International Ground Source Heat Pump Association for sizing borehole heat exchanger. In this paper, an existing system is analyzed, for a 60 kilo Watts heat pump in an area of Finland with a ground source 250 meters of Borehole Heat Exchanger. Coefficient of Performance for current scenario is calculated, an optimal length is found for the heat capacity of the heat pump to enhance the performance of the system. Improved coefficient of performance is presented along with an easy method of finding the optimal length of the ground source.fi=vertaisarvioitu|en=peerReviewed

Substitute or addition to hypermobile lifestyles? Second home mobility and Finnish CO2 emissions

Tourism produces an increasing share in global greenhouse gas (GHG) emissions. These are mostly derived from transport emissions, and long-haul air travel in particular. Short-haul domestic tourism is believed by some to be a potential substitute for long-haul tourism. Using the example of Finland this paper examines the extent to which domestic second home tourism can substitute for other leisure trips and therefore contribute to reductions of travel-generated GHG emissions. Survey data are used to evaluate the CO2 emissions caused by travel to domestic second homes, and to create statistical models that verify if the owners of domestic second homes travel to other leisure destinations less frequently than others, and if they cause less emissions by their leisure mobility than others with comparable economic and demographic background. We find that although the owners and users of domestic second homes travel for other leisure purposes less frequently than others, this does not mean their leisure mobility generates less emissions. Overall, owners of second homes produce significantly more CO2 by their leisure mobility than non-owners. The use of second homes does not seem to be a substitute for high emission long-haul travels, but rather a part of an overall highly mobile leisure lifestyle. It is therefore necessary to better understand and influence the entire range of individual mobility behaviours in order to reduce travel-related GHG emissions

Seasonal temperature variation in heat collection liquid used in renewable, carbon-free heat production from urban and rural water areas

A renewable energy source called sediment energy is based on heat collection with tubes similar to those used in ground energy and is installed inside a sediment layer under water body. In this paper, an investigation of temperature behaviour of heat carrier liquid is made during several years to evaluate utilization of sediment energy. This is done by evaluating temperature variations of heat carrier liquid and its correlation to air temperature. This increases advancement of knowledge how the temperature of the sediment recovers from the heat collection. The temperature variation of the liquid seems to correlate with the mean monthly air temperature. The selected methods clearly indicate that sediment energy seems to be yearly renewable because there is a clear correlation between air temperature and heat carrier liquid temperature.© Authors. This is an open access journal distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)fi=vertaisarvioitu|en=peerReviewed