Role and function of nonmuscle alpha-actinin-1 and -4 in regulating distinct subcategories of actin stress fibers in mammalian cells

Actin stress fibers are dynamic structures in the cytoskeleton, which respond to mechanical stimuli and affect cell motility, adhesion and invasion of cancer cells. In nonmuscle cells, stress fibers have been subcategorized to three distinct stress fiber types: dorsal and ventral stress fibers and transverse arcs. These stress fibers are dissimilar in their subcellular localization, connection to substratum as well as in their dynamics and assembly mechanisms. Still uncharacterized is how they differ in their function and molecular composition. Here, I have studied involvement of nonmuscle alpha-actinin-1 and -4 in regulating distinct stress fibers as well as their localization and function in human U2OS osteosarcoma cells. Except for the correlation of upregulation of alpha-actinin-4 in invasive cancer types very little is known about whether these two actinins are redundant or have specific roles. The availability of highly specific alpha-actinin-1 antibody generated in the lab, revealed localization of alpha-actinin-1 along all three categories of stress fibers while alphaactinin-4 was detected at cell edge, distal ends of stress fibers as well as perinuclear regions. Strikingly, by utilizing RNAi-mediated gene silencing of alpha-actinin-1 resulted in specific loss of dorsal stress fibers and relocalization of alpha-actinin-4 to remaining transverse arcs and ventral stress fibers. Unexpectedly, aberrant migration was not detected in cells lacking alpha-actinin-1 even though focal adhesions were significantly smaller and fewer. Whereas, silencing of alpha-actinin-4 noticeably affected overall cell migration. In summary, as part of my master thesis study I have been able to demonstrate distinct localization and functional patterns for both alpha-actinin-1 and -4. I have identified alpha-actinin-1 to be a selective dorsal stress fiber crosslinking protein as well as to be required for focal adhesion maturation, while alpha-actinin-4 was demonstrated to be fundamental for cell migration.

Luonnonhoitopellot maatalousympäristön luonnon monimuotoisuuden edistämisessä

Luonnonhoitopellot lisättiin uutena vapaaehtoisena toimenpiteenä maatalouden ympäristötukeen vuonna 2009. Luonnonhoitopeltoihin kuuluvat monivuotiset nurmipellot sekä niitty-, riista- ja maisemakasveilla kylvetyt pellot. Toimenpiteen avulla pyritään suojelemaan ja lisäämään maatalousympäristön luonnon monimuotoisuutta sekä muun muassa vähentämään maatalouden ravinnehuuhtoumia. Vuonna 2010 luonnonhoitopeltoja oli yli seitsemän prosenttia Suomen viljelyalasta. Luonnonhoitopeltojen ympäristövaikutusten arvioiminen ja toimenpiteen kehittäminen on tärkeää, jotta toimenpiteeseen käytettävät varat eivät valu hukkaan. Tämän tutkimuksen tavoitteena oli selvittää, millainen merkitys luonnonhoitopelloilla on maatalousympäristön monimuotoisuuden kannalta; millaiset luonnonhoitopellot ovat monimuotoisuuden kannalta arvokkaimpia; ja kuinka toimenpidettä kannattaa kehittää. Kysymyksiin pyrittiin vastaamaan tutkimalla putkilokasvilajistoa, -lajirikkautta ja kasvillisuuden rakennetta erilaisilla luonnonhoitopelloilla, sekä vertaamalla luonnonhoitopeltojen kasvillisuutta pientareiden ja niittyjen kasvillisuuteen. Maastotyö luonnonhoitopelloilla tehtiin kesällä 2010 Uudenmaan ja Pohjois-Pohjanmaan ELY-keskusalueilla. Lisäksi tutkimuslohkoista kerättiin tietoja viljelijäkyselyn kautta. Niittypellot osoittautuivat tutkimuksessa lajirikkaimmaksi luonnonhoitopeltotyypiksi, mikä selittynee lähinnä sillä, että ne kylvetään heikosti kilpailukykyisellä siemenseoksella. Nurmi- ja niittypelloilla lohkon viljavuus korreloi negatiivisesti lajirikkauden kanssa. Lajikoostumukseltaan kaikki luonnonhoitopellot eroavat toisistaan sekä maatalousympäristön puoliluonnontilaisista elinympäristöistä, ja lisäävät siten monimuotoisuutta maisematasolla. Luonnonhoitopeltojen lajisto ei ole kuitenkaan suojelun kannalta erityisen arvokasta. Toimenpiteen maatalousympäristöä rikastuttavaa vaikutusta vähentää, että tällä hetkellä valtaosa luonnonhoitopelloista on monivuotisia nurmipeltoja. Luonnonhoitopeltojen siemenseoksia kehittämällä, perustamis- ja hoitomenetelmiä tutkimalla ja neuvontaan panostamalla voidaan lisätä luonnonhoitopeltojen arvoa niin luonnon, viljelijän kuin yhteiskunnankin kannalta.

Plant communities of field margins : the effects of management and environmental factors on species composition and diversity

Agri-environmental schemes have so far resulted in only minor positive implications for the biodiversity of agricultural environments, in contrast to what has been expected. Land-use intensification has decreased landscape heterogeneity and the amount of semi-natural habitats. Field margins are uncultivated areas of permanent vegetation located adjacent to fields. Since the number of these habitats is high, investing in their quality may result in more diverse agricultural landscapes. Field margins can be considered as multifunctional habitats providing agronomic, environmental and wildlife services. This thesis aimed at examining the plant communities of different types of field margin habitats and the factors affecting their species diversity and composition. The importance of edaphic, spatial and management factors was studied on regional, landscape and habitat scales. Vegetation surveys were conducted on regional and landscape scales and a field experiment on cutting management was conducted on a habitat scale. In field margin plant communities, species appeared to be indicators of high or intermediate soil fertility and moist soil conditions. The plant species diversity found was rather low, compared with most species-rich agricultural habitats in Finland, such as dry meadows. Among regions, land-use history, main production line, natural species and human induced distribution, climate and edaphic factors were elements inducing differences in species composition. The lowest regional species diversity of field margins was related to intensive and long-term cereal production. Management by cutting and removal or grazing had a positive effect on plant species diversity. The positive effect of cutting and removal on species richness was also dependent on the adjacent source of colonizing species. Therefore, in species-poor habitats and landscapes, establishment of margins with diverse seed mixtures can be recommended for enhancing the development of species richness. However, seed mixtures should include only native species preferably local origin. Management by cutting once a year for 5 years did not result in a decline in dominance of a harmful weed species, Elymus repens, showing that E. repens probably needs cutting more frequently than once per year. Agri-environmental schemes should include long-term contracts with farmers for the establishment, and management by cutting and removal or grazing, of field margins that are several metres wide. In such schemes, the timing and frequency of management should be planned so as not to harm other taxa, such as the insects and birds that are dependent on these habitats. All accidental herbicide drifts to field margins should be avoided when spraying the cultivated area to minimize the negative effects of sprayings on vegetation. The harmful effects of herbicides can be avoided by organic farming methods.

Population genetics of the invasive plant species Impatiens glandulifera in Southern Finland

Biological invasions affect biodiversity worldwide, and, consequently, the invaded ecosystems may suffer from significant losses in economic and cultural values. Impatiens glandulifera Royle (Balsaminaceae) is an invasive annual herb, native to the western Himalayas and introduced into Europe in the 19th century as a garden ornamental plant. The massive invasion of I. glandulifera is due to its high reproductive output, rapid growth and its ability to outcompete native species. In Finland, the first observations regarding the presence of I. glandulifera date from the year 1947, and today it is considered a serious problem in riparian habitats. The aim of this master’s thesis research is to reveal the population genetic structure of I. glandulifera in Finland and to find out whether there have been one or multiple invasions in Finland. The study focuses on investigating the origin of I. glandulifera in Southern Finland, by comparing plant samples from the Helsinki region with those from its native region and other regions of invasion. Samples from four populations in Helsinki and from the United Kingdom, Canada, India and Pakistan were collected and genotyped using 11 microsatellite markers. The genetic analyses were evaluated using the programs Arlequin and Structure. The results of the genetic analyses suggested that I. glandulifera has been introduced to Finland more than once. Multiple introductions are supported by the higher level of genetic diversity detected within and among Finnish populations than would be expected for a single introduction. Results of the Bayesian Structure analysis divided the four Finnish populations into four clusters. This geographical structure was further supported by pairwise Fst values among populations. The causes and potential consequences of such multiple introductions of I. glandulifera in Finland and further perspectives are discussed.

Helsingin metropolialueen maisemaekologiset muutokset vuosina 1955-2009

Landscape is shaped by natural environment and increasingly by human activity. In landscape ecology, the concept of landscape can be defined as a kilometre-scale mosaic formed by different land-use types. In Helsinki Metropolitan Region, the landscape change caused by urbanization has accelerated after the 1950s. Prior to that, the landscape of the region was mainly only shaped by agriculture. The goal of this study was in addition to describing the landscape change to discuss the factors impacting the landscape change and evaluate thelandscape ecological impacts of the change. Three study areas at different distances from Helsinki city centre were chosen in order to look at the landscape change. Study areas were Malmi, Espoo and Mäntsälä regions representing different parts of the urban-to-rural gradient in 1955, 1975, 1990 and 2009. Land-use of the maps was then digitized into five classes: agricultural lands, semi-natural grasslands, built areas, waters and others using GIS methods. First, landscape change was studied using landscape ecological indices. Indices used were PLAND i.e. the proportions of the different land-use types in the landscape; MPS, SHEI and SHDI which describe fragmentation and heterogeneity of the landscape; and MSI and ED which are measures of patch shape. Second, landscape change was studied statistically in relation to topography, soil and urban structure of the study areas. Indicators used concerning urban structure were number of residents, car ownership and travel-related zones of urban form which indicate the degree of urban sprawl within the study areas. For the statistical analyses, each of the 9.25 x 9.25 km sized study areas was further divided into grids with resolution of 0.25 x 0.25 kilometres. Third, the changes in the green structure of the study areas were evaluated. The landscape change reflected by the proportions of the land-use types was the most notable in Malmi area where a large amount of agricultural land was developed from 1955 to 2009. The proportion of semi-natural grasslands also showed an interesting pattern in relation to urbanization. When urbanization started, a great number of agricultural lands were abandoned and turned into semi-natural grasslands but as the urbanization accelerated, the number of semi-natural grasslands started to decline because of urban densification. Landscape fragmentation and heterogeneity were the most widespread in Espoo study area which is not only because of the great differences in relative heights within the region but also its location in the rural-urban fringe. According to the results, urbanization induced agricultural lands to be more regular in shape both spatially and temporally whereas for built areas and semi-natural grasslands the impact of urbanization was reverse. Changes in landscape were the most insignificant in the most rural study area Mäntsälä. In Mäntsälä, built area per resident showed the greatest values indicating a widespread urban sprawl. The values were the smallest in highly urbanized Malmi study area. Unlike other study areas, in Mäntsälä the proportion of developing land in the ecologically disadvantageous cardependent zone was on the increase. On the other hand, the green structure of the Mäntsälä study area was the most advantageous whereas Malmi study area showed the most ecologically disadvantageous structure. Considering all the landscape ecological criteria used, the landscape structure of Espoo study area proved to be the best not least because of the great heterogeneity of its landscape. Thus the study confirmed the previous results according to which landscape heterogeneity is the most significant in areas exposed to a moderate human impact.

Viherrevonhäntä ja kananhirssi vieraslajeina Suomessa

Kasvit ovat kautta aikojen levinneet uusille elinpaikoille. Kasvin asettumista uuteen paikkaan voidaan tarkastella prosessina, jossa on erilaisia vaiheita ja eri vaiheissa eri tekijät ovat tärkeitä. Ilmasto ja erityisesti lämpötila vaikuttavat kasvien levinneisyyteen ja leviämiseen uusille paikoille ja siksi ilmaston lämpenemisen ennustetaan siirtävän kasvien levinneisyysalueita kohti pohjoista. On mahdollista, että Suomeenkin leviäisi etelämmästä muiden kasvien ohella haitallisia rikkakasvilajeja, kuten esimerkiksi viherrevonhäntä (Amaranthus retroflexus L.) ja kananhirssi (Echinochloa crus-galli L. Beauv.). Tämän tutkimuksen tarkoituksena oli selvittää, selviävätkö viherrevonhäntä ja kananhirssi Suomessa pelto-olosuhteissa ja pohtia niiden vakiintumisen ja leviämisen mahdollisuuksia. Toinen tarkoitus oli selvittää ilmaston lämpenemisen vaikutusta näiden rikkakasvien kasvuun. Tutkimus suoritettiin kenttä- sekä kasvihuonekokeena. Viherrevonhäntä kasvoi pellolla hyvin huolimatta myöhäisestä itämisestä, mutta kananhirssi iti ja kasvoi pellolla huonosti. Kasvihuoneessa molemmat kasvoivat hyvin. Kilpailu vähensi viherrevonhännän ja kananhirssin vegetatiivista kasvua vain kasvihuoneessa, mutta siementuottoon kilpailu vaikutti sekä kasvihuoneessa että pellolla. Kasvihuoneessa korkeampi lämpötila ei vaikuttanut viherrevonhännän tai kananhirssin vegetatiiviseen kasvuun, mutta viherrevonhännän siementuotto parani lämpimämmässä. Lämpötilalla ei ollut vaikutusta kananhirssin siementuotantoon. Tutkimuksen tuloksista voidaan päätellä, että viherrevonhäntä voi hyvinkin kasvaa Suomessa jo nykyisissä lämpötiloissa, mutta siementuotto ei välttämättä olisi varmaa. Viherrevonhäntä voisi näin ollen hyötyä tulevaisuuden pidemmästä kasvukaudesta. Kananhirssin osalta tulokset olivat ristiriitaiset ja ilmaston lämpenemisen vaikutuksia kananhirssiin on tämän tutkimuksen perusteella hankala arvioida.

Microfinance, Efficiency and Agricultural Production in Bangladesh

The objectives of this study were to make a detailed and systematic empirical analysis of microfinance borrowers and non-borrowers in Bangladesh and also examine how efficiency measures are influenced by the access to agricultural microfinance. In the empirical analysis, this study used both parametric and non-parametric frontier approaches to investigate differences in efficiency estimates between microfinance borrowers and non-borrowers. This thesis, based on five articles, applied data obtained from a survey of 360 farm households from north-central and north-western regions in Bangladesh. The methods used in this investigation involve stochastic frontier (SFA) and data envelopment analysis (DEA) in addition to sample selectivity and limited dependent variable models. In article I, technical efficiency (TE) estimation and identification of its determinants were performed by applying an extended Cobb-Douglas stochastic frontier production function. The results show that farm households had a mean TE of 83% with lower TE scores for the non-borrowers of agricultural microfinance. Addressing institutional policies regarding the consolidation of individual plots into farm units, ensuring access to microfinance, extension education for the farmers with longer farming experience are suggested to improve the TE of the farmers. In article II, the objective was to assess the effects of access to microfinance on household production and cost efficiency (CE) and to determine the efficiency differences between the microfinance participating and non-participating farms. In addition, a non-discretionary DEA model was applied to capture directly the influence of microfinance on farm households production and CE. The results suggested that under both pooled DEA models and non-discretionary DEA models, farmers with access to microfinance were significantly more efficient than their non-borrowing counterparts. Results also revealed that land fragmentation, family size, household wealth, on farm-training and off farm income share are the main determinants of inefficiency after effectively correcting for sample selection bias. In article III, the TE of traditional variety (TV) and high-yielding-variety (HYV) rice producers were estimated in addition to investigating the determinants of adoption rate of HYV rice. Furthermore, the role of TE as a potential determinant to explain the differences of adoption rate of HYV rice among the farmers was assessed. The results indicated that in spite of its much higher yield potential, HYV rice production was associated with lower TE and had a greater variability in yield. It was also found that TE had a significant positive influence on the adoption rates of HYV rice. In article IV, we estimated profit efficiency (PE) and profit-loss between microfinance borrowers and non-borrowers by a sample selection framework, which provided a general framework for testing and taking into account the sample selection in the stochastic (profit) frontier function analysis. After effectively correcting for selectivity bias, the mean PE of the microfinance borrowers and non-borrowers were estimated at 68% and 52% respectively. This suggested that a considerable share of profits were lost due to profit inefficiencies in rice production. The results also demonstrated that access to microfinance contributes significantly to increasing PE and reducing profit-loss per hectare land. In article V, the effects of credit constraints on TE, allocative efficiency (AE) and CE were assessed while adequately controlling for sample selection bias. The confidence intervals were determined by the bootstrap method for both samples. The results indicated that differences in average efficiency scores of credit constrained and unconstrained farms were not statistically significant although the average efficiencies tended to be higher in the group of unconstrained farms. After effectively correcting for selectivity bias, household experience, number of dependents, off-farm income, farm size, access to on farm training and yearly savings were found to be the main determinants of inefficiencies. In general, the results of the study revealed the existence substantial technical, allocative, economic inefficiencies and also considerable profit inefficiencies. The results of the study suggested the need to streamline agricultural microfinance by the microfinance institutions (MFIs), donor agencies and government at all tiers. Moreover, formulating policies that ensure greater access to agricultural microfinance to the smallholder farmers on a sustainable basis in the study areas to enhance productivity and efficiency has been recommended. Key Words: Technical, allocative, economic efficiency, DEA, Non-discretionary DEA, selection bias, bootstrapping, microfinance, Bangladesh.