The Baltic Sea was earlier identified as a highly polluted brackish water body and still is. The high concentrations of polychlorinated biphenyls (PCBs), p,p’-DDT and related compounds led to severe effects on several species in the Baltic region. However, the situation has improved significantly since the 1970’s resulting in lower exposures to a range of pollutants and healthier wildlife populations. Independent of this positive trend there are still new chemicals leaking into the Baltic Sea environment. The objective of this thesis is to improve the knowledge of sulfone containing compounds and pollutant metabolites in wildlife, with special interest in bis(4-chlorophenyl) sulfone (BCPS) distribution, temporal trend and exposure levels, and the methylsulfonyl-PCBs (MeSO2-PCBs). The latter are of particular interest for chiral MeSO2-PCBs. BCPS is used for the production of high temperature polymers and was detected as an environmental contaminant ten years ago. PCBs, p,p’-DDT and related compounds are still of scientific interest. BCPS is biomagnified and especially in the bird guillemot which has levels of up to 2000 ng BCPS/g fat compared to the grey seal with concentrations of about 60 ng/g fat. The seal levels are similar to the herring, the prey of the bird and seal, with concentrations of 30 ng BCPS/g fat. The guillemot concentration of BCPS has been similar over the last 30 years with a minimal, but significant, annual decline of 1.6%. The reason for the slow decline is not yet understood. Also MeSO2-PCBs and 3-MeSO2-DDE show a small decrease over time in guillemot egg (3 and 9%, respectively), which is less then for the parent compounds. This shows that the sulfone metabolites are more persistent than their precursors in the guillemot. Furthermore, all these sulfone containing compounds showed a specific retention to liver comparing different tissues in grey seal. The atropisomers of the chiral MeSO2-PCB were analysed in both the guillemot and the grey seal and showed to occur in a skewed relationship. This is particularly pronounced in seals where one atropisomer of each chiral congener is very dominating. The dominating atropisomers have been identified with an absolute R configuration, in both grey seal and guillemot. An enantioselective metabolism was indicated to occur when experimentally tested by CB-132 in rat. This thesis is stressing the high specificity in wildlife for one atropisomer in the pair of chiral PCB methyl sulfones being PCB metabolites, and the high BCPS concentrations in guillemot hatching in the Baltic proper.

Microtransplantation of mammalian neurolemma into Xenopus laevis oocytes has been used to study ion channels in terms of their structure and function in the central nervous system. Use of microtransplanted neurolemma is advantageous in that tissue can be obtained from various sources, ion channels and receptors are present in their native configuration and they can be used to evaluate numerous channelpathies caused by environmental toxicants. Here we show that Xenopus oocytes injected with fragments of rat brain neurolemma successfully express functional native ion channels that are assembled in their own plasma membrane. Using a high throughput two electrode voltage clamp (TEVC) electrophysiological system, currents that were sensitive to tetrodotoxin (TTX), omega-conotoxin MVIIC, and tetraethylammonium (TEA) were detected, indicating the presence of multiple voltage-sensitive ion channels (voltage-sensitive sodium, calcium and potassium channels, respectively). In this current research, a “proof-of-principle” experiment was conducted where TTX-sensitive voltage-sensitive sodium channel (VSSC) currents were measured. VSSCs are a well-established site of action for 1,1,1-trichloro-2,2-di(4-chlorophenyl)ethane (DDT) but not for its non-toxic metabolite 1,1-bis-(4-chlorophenyl)-2,2-dichloroethene (DDE). A differential sensitivity of DDT versus DDE on TTX-sensitive sodium current in neurolemma-injected oocytes was determined. DDT elicited an increase in depolarization-dependent, TTX-sensitive sodium current while DDE had no significant effect. Additionally, DDT resulted in a slowing of sodium channel inactivation kinetics whereas DDE has no similar effect. These results are consistent with the findings obtained using heterologous expression of single isoforms of rat brain VSSCs by injecting cRNA into Xenopus oocytes. By demonstrating the classic structural activity relationship of DDT and DDE on mammalian voltage-gated sodium channels isolated in rat brain neurolemma, this study supports the use of automated high-throughput electrophysiology to study the effects of various environmental toxicants on multiple mammalian cellular targets. More importantly, using rat brain neurolemma ensures that the proteins of interest have been transcribed and have undergone all the necessary post-translational modifications before they were injected and expressed in the Xenopus oocytes which is not the case for traditional heterologous expression.

O processo de isquemia-reperfusão é responsável pela geração de um dano agudo em uma série de órgãos do corpo humano, e, no coração, é o principal causador da doença crônica conhecida por insuficiências cardíaca. Atualmente não existe nenhuma opção terapêutica disponível na prática clínica contra esta injúria. Com o objetivo de desenvolver uma nova estratégia de combate a este dano, no presente trabalho investigamos a promessa da aplicação da recém-descoberta via UPRam num modelo de hipóxia reoxigenação in-vitro, sem obter sucesso. Contudo, os resultados gerados nestes experimentos forneceram pistas de que o uso do desacoplador CCCP é capaz de reduzir o dano deste insulto, porém o mecanismo celular responsável por esta proteção permanece desconhecido. Tentativas de desvendar este mecanismo utilizando a via lisossomal-autofágica ou a clivagem de OPA-1 falharam, mas produziram importantes insights a respeito do papel da protease mitocondrial OMA-1 no processo de hipóxia-reoxigenação, abrindo caminho para novos estudos subsequentes. / Ischemia-reperfusion injury is a process that occurs in many human organs including the heart, where it is the main trigger to heart failure, a chronic disease that kills over 40% patients only five years following the first diagnosis. Despite the bulky research on the subject, there is no available therapy on clinical practice against this insult. Attempting to develop a novel strategy to mitigate this damage, we investigated if the pro-survival effect of the recently discovered UPRam pathway could be protective in an in-vitro model of ischemia reperfusion. Despite the negative results regarding its conservation on mammalian cells, treatment with the mitochondrial uncoupler CCCP was proven to reduce cell death under this process, but the cellular mechanism responsible for this protection remained elusive. Aspiring to unravel this cellular response, we tested whether autophagy or OPA-1 cleavage was capable of abrogating the verified protection, but the results came back negative. Regardless of that, the behavior of OMA-/- cells over H/R stress has given new insights on novel strategies comprising I/R injury abrogation.