Weak and strong invaders: which biotic factors shape interactions among Ponto-Caspian invasive gammaridean species

Rozprawa doktorska składa się z trzech opublikowanych publikacji naukowych.Rozprawa doktorska dra Michała Rachalewskiego pt. „Weak and strong invaders: which biotic factors shape interactions among Ponto-Caspian invasive gammaridean species?” otrzymała nagrodę w VII edycji Konkursu „Ekologiczny magister i doktor" w kategorii ekologiczny doktor. Zwycięska praca została napisana pod kierunkiem naukowym dr hab. Karoliny Bąceli-Spychalskiej z Katedry Zoologii Bezkręgowców i Hydrobiologii UŁ. Konkurs „Ekologiczny magister i doktor” organizowany jest przez Wojewódzki Fundusz Ochrony Środowiska i Gospodarki Wodnej w Łodzi. Celem Konkursu jest wyłonienie przez Zarząd WFOŚiGW w Łodzi najlepszych prac magisterskich i rozpraw doktorskich z dziedziny ochrony środowiska, które oceniane były zarówno pod względem naukowym jak i praktycznym.The aim of this thesis was to investigate interactions and possible biotic factors that could be agents modulating coexistence and dispersal of three most widespread Ponto-Caspian species Dikerogammarus villosus (Sovinsky, 1894), Dikerogammarus haemobaphes (Eichwald, 1841) and Pontogammarus robustoides (G.O. Sars, 1894). Each chapter presented in this thesis is focused on a different biotic factor that defines the boundaries of possible coexistence of the studied species. This thesis fills some gaps in knowledge about possible ecological mechanisms that stand behind the invasion of those animals. Thus, their temperature preferences were investigated to find whether this factor might determine coexistence of species by relocation leading to their spatial segregation among microhabitats. Ponto-Caspian amphipods are often highly infected with microsporidian parasites, which coevolved with them in their native region and undergo the invasion with their hosts to Europe, Thus, incorporation of microsporidia into study upon thermal preferences of Ponto-Caspian amphipods allowed to investigate both infection presence and temperature selection as agents capable of determining the possibility of coexistence of the studied amphipods. Therefore, physical and chemical contact with competitors, thermal preferences and possible modulators of these factors – microsporidian parasites were chosen as imsportant factors potentially affecting the intensity and direction of amphipod migrations. All ecological experiments were conducted with intention to define behaviour of each studied species while facing with those factors.Polish National Science Centre grants 2011/03/D/NZ8/03012 and 2012/05/B/NZ8/0047

What doesn’t kill you doesn’t make you stronger: Parasites modify interference competition between two invasive amphipods

We used a freshwater amphipod-microsporidian model (Ponto-Caspian hosts: Dikerogammarus villosus and D. haemobaphes, parasite: Cucumispora dikerogammari) to check whether parasites affect biological invasions by modulating behaviour and intra- and interspecific interactions between the invaders. We tested competition for shelter in conspecific and heterospecific male pairs (one or both individuals infected or non-infected). In general, amphipods of both species increased their shelter occupancy time when accompanied by infected rather than non-infected conspecifics and heterospecifics. Infected amphipods faced lower aggression from non-infected conspecifics. Moreover, D. villosus was more aggressive than D. haemobaphes and more aggressive towards conspecifics vs. heterospecifics. In summary, infection reduced the intra- and interspecific competitivity of amphipods, which became less capable of defending their shelters, despite their unchanged need for shelter occupancy. Dikerogammarus haemobaphes, commonly considered as a weaker competitor, displaced by D. villosus from co-occupied locations, was able to compete efficiently for the shelter with D. villosus when microsporidian infections appeared on the scene. This suggests that parasites may be important mediators of biological invasions, facilitating the existence of large intra- and interspecific assemblages of invasive alien amphipods

Bioprinting of Perfusable, Biocompatible Vessel-like Channels with dECM-Based Bioinks and Living Cells

There is a growing interest in the production of bioinks that on the one hand, are biocompatible and, on the other hand, have mechanical properties that allow for the production of stable constructs that can survive for a long time after transplantation. While the selection of the right material is crucial for bioprinting, there is another equally important issue that is currently being extensively researched—the incorporation of the vascular system into the fabricated scaffolds. Therefore, in the following manuscript, we present the results of research on bioink with unique physico-chemical and biological properties. In this article, two methods of seeding cells were tested using bioink B and seeding after bioprinting the whole model. After 2, 5, 8, or 24 h of incubation, the flow medium was used in the tested systems. At the end of the experimental trial, for each time variant, the canals were stored in formaldehyde, and immunohistochemical staining was performed to examine the presence of cells on the canal walls and roof. Cells adhered to both ways of fiber arrangement; however, a parallel bioprint with the 5 h incubation and the intermediate plating of cells resulted in better adhesion efficiency. For this test variant, the percentage of cells that adhered was at least 20% higher than in the other analyzed variants. In addition, it was for this variant that the lowest percentage of viable cells was found that were washed out of the tested model. Importantly, hematoxylin and eosin staining showed that after 8 days of culture, the cells were evenly distributed throughout the canal roof. Our study clearly shows that neovascularization-promoting cells effectively adhere to ECM-based pancreatic bioink. Summarizing the presented results, it was demonstrated that the proposed bioink compositions can be used for bioprinting bionic organs with a vascular system formed by endothelial cells and fibroblasts

Some like it hot: factors impacting thermal preferences of two Ponto-Caspian amphipods Dikerogammarus villosus (Sovinsky, 1894) and Dikerogammarus haemobaphes (Eichwald, 1841)

Temperature is a crucial factor determining biology and ecology of poikilothermic animals. It often constitutes an important barrier for invasive species originating from different climate zones but, on the other hand, may facilitate the invasion process of animals with wide thermal preferences and high resistance to extreme temperatures. In our experimental study, we investigated the thermal behaviour of two Ponto-Caspian amphipod crustaceans—Dikerogammarus villosus and Dikerogammarus haemobaphes. Both species are known to live under a wide range of thermal conditions which may promote their invasion. Moreover, both these amphipods are hosts for microsporidian parasites which co-evolved with them within the Ponto-Caspian region and spread in European waters. As the presence of a parasite may influence the thermal preferences of its host, we expected to observe behavioural changes in infected individuals of the studied amphipods leading to (1) behavioural fever (selecting a warmer habitat) or (2) anapyrexia (selecting a colder habitat). The experiment (N = 20) was carried out for 30 min in a 100 cm. 20 cm from boths sides were not avaliable for amphipods long thermal gradient (0–40 °C), using 30 randomly selected adult amphipod individuals of one species. At the end of each trial, we checked the position of amphipods along the gradient and determined their sex and infection status (uninfected or infected by one of microsporidium species). D. villosus was infected with Cucumispora dikerogammari whereas D. haemobaphes was a host for C. dikerogammari, Dictyocoela muelleri or D. berillonum. Thermal preferences of amphipods depended on their species and sex. Females of D. villosus preferred warmer microhabitats (often much above 30 °C) than conspecific males and females of D. haemobaphes, whereas no significant differences were found among males of both species and both sexes of D. haemobaphes. Moreover, infected males of D. villosus stayed in warmer water more often than uninfected males of this species, selecting temperatures higher than 30 °C, which may be explained either as a behavioural fever constituting a defence mechanism of a host against the infection, or as a parasite manipulation of the host behaviour increasing the parasite fitness. On the other hand, none of the parasite species affected the thermal preferences of D. haemobaphes, including also C. dikerogammari, changing the behaviour of D. villosus. Our research presents the complexity of the thermal behaviour of studied amphipods and the evidence that microsporidia may trigger a change in temperature preferendum of their host species and those observations may be the result of different host-parasite coevolution time which may vary for the two host species (Poulin, 2010)

Examination of the application of quantitative analysis of CT brain images in ischaemic stroke and brain tumour detection – preliminary test

Introduction: Neuroimaging is a standard examination implemented for diagnosis of various pathologies of the central nervous system. The fundamental diagnostic procedures in medical imaging of the central nervous system are computed tomography and magnetic resonance imaging. In case of a sudden focal or generalized onset of brain dysfunctions at first we should think about stroke. A very important test if stroke is suspected is computed tomography. In this paper we would like to check if it is possible to distinguish two pathologies of the cerebrum: ischaemic stroke and tumour, using quantitative analysis of selected abnormalities. Material and methods: Analysis is based on comparison of two pathologies (ischaemic stroke and tumour). Two sets of images were prepared. Analysis is performed to distinguish abnormalities observed on computed tomography brain images from healthy tissue. The image analysis includes data conversion, normalization of region of interest, estimation of the number of texture features, features selection based on four different methods of selection and finally classification based on artificial neural network classifier. Results: In the examination, different effectiveness of used methods was observed. Quantitative analysis of selected texture features allows to differentiate two classes of pathologies. Also an important observation is that the artificial neural network can be a useful tool in data classification and analysis. Conclusions: The performed analysis is effective but only for small number of data. That is why it still needs to be conducted on a larger set of data. It will be also necessary to repeat classification a number of times and to perform data validation in order to confirm effectiveness of the presented method. After that we can hope to get really satisfying results.Wstęp: Neuroobrazowanie jest standardowym badaniem stosowanym w diagnostyce ośrodkowego układu nerwowego (OUN). Podstawowymi narzędziami diagnostycznymi w obrazowaniu OUN są tomografia komputerowa (TK) oraz rezonans magnetyczny. W przypadku wystąpienia nagłych ogniskowych lub uogólnionych objawów neurologicznych należy w pierwszej kolejności podejrzewać udar mózgu. Obecnie badaniem pierwszego rzutu w diagnostyce neuroradiologicznej jest badanie TK. W przedstawionej pracy podjęto próbę sprawdzenia, czy jest możliwa ilościowa analiza obrazów TK, pozwalająca odróżnić zmiany rozrostowe OUN od udarów niedokrwiennych. Materiały i metody: Analizę oparto na porównaniu dwóch patologii OUN: udaru niedokrwiennego oraz zmiany rozrostowej. Ocenie poddano obrazy TK mózgowia, na których wyodrębniono zmianę patologiczną. Podczas kolejnych etapów pracy przeprowadzono: konwersję danych, definiowanie obszarów zainteresowania (ROI), estymację cech tekstury, selekcję cech z zastosowaniem czterech różnych metod oraz klasyfikację opartą na sztucznej sieci neuronowej. Wyniki: Odnotowano różną skuteczność zastosowanych metod, co dało podstawę do stwierdzenia, że ilościowa analiza wybranych cech tekstury obrazu pozwala odgraniczyć klasy przypisane do omawianych patologii, natomiast użycie sztucznych sieci neuronowych do klasyfikacji danych wskazuje na ich skuteczność i przydatność jako narzędzi stosowanych w analizie wybranych danych. Podsumowanie: W sytuacji gdy badanie neuroradiologiczne nie wypada jednoznacznie, a leczenie udaru i guza mózgu różnią się diametralnie, istnieje możliwość zastosowania przedstawionej analizy w celu skrócenia czasu potrzebnego do postawienia właściwej diagnozy. Przedstawione wyniki mają jednak charakter wstępny i wymagają dalszej analizy na większej grupie pacjentów