Viral inhibition of apoptotic pathways

Programirana stanična smrt je orkestrirani biokemijski proces koji ultimativno završava smrću stanice. Apoptoza je najbolje opisani oblik programirane stanične smrti. Očituje se kondenzacijom kromatina, disfunkcijom mitohondrija te aktivacijom staničnih proteaza i nukleaza pa dovodi do razgradnje DNA. Ne uzrokuje upalne promjene, što je razlikuje od nekroze. Ključna je komponenta u normalnom životu mnogostaničnih organizama, sa svojom ulogom u razvoju, imunosti i održavanju homeostaze. Postoje dva glavna puta programirane stanične smrti: unutarnji i vanjski, a oba rezultiraju aktivacijom izvršnih proteolitičkih enzima – kaspaza. Vanjski put se odnosi na apoptozu pokrenutu putem „receptora smrti“, a unutarnji ovisi o općem metaboličkom stanju stanice i integritetu mitohondrijske membrane. S obzirom na bitnu ulogu apoptoze u imunološkom odgovoru, mnogi virusi, kao dio svog arsenala, imaju sposobnost modulacije apoptotičkih puteva domaćina. Suprotno je očekivanom da tako jednostavni organizmi mogu utjecati na ovako važne puteve relativno složenih stanica domaćina. No, virusi mogu inducirati ili inhibirati proces programirane stanične smrti kroz manipulaciju ključnih apoptotičkih proteina. U ovom radu predstavljene su glavne strategije kojima se koriste virusi kako bi omeli puteve apoptoze te si na taj način osigurali dovoljno vremena za uspješno umnožavanje i transmisiju – od kodiranja za funkcionalne homologe proteinske porodice Bcl-2 do ekspresije viralnih genskih produkata kojima utječu na regulaciju staničnog ciklusa, oksidativnog stresa, transkripciju gena vezanih za apoptozu te raspoloživost signalnih medijatora i aktivnost kaspaza.Programmed cell death is an orchestrated biochemical process that leads ultimately to the demise of the cell. Apoptosis is the best characterized form of programmed cell death. Cell changes that have been observed while undergoing apoptosis are chromatin condensation, mitochondria disruption, protease and nuclease activation finally resulting in DNA fragmentation. While necrosis often results in inflammation and adaptive immunity, no inflammatory reaction is associated with apoptosis. Apoptosis is a crucial component for normal multicellular life, playing a key role in development, immunity and the maintenance of homeostasis. There are two main apoptotic pathways: the intrinsic and extrinsic pathways which both lead to caspase (effectors proteolytic enzymes) activation. The extrinsic pathway operates via death receptors on the cell surface, whereas the intrinsic one depends on general metabolic state of cell and mitochondrial membrane integrity. Due to great importance of apoptosis in immunity, many viruses have, as a part of their arsenal, the ability to modulate the apoptotic pathways of the host. It is counter-intuitive that such simple organisms would efficiently affect these most crucial pathways within host, given the relative complexity of the host cells. Yet, viruses have the potential to initiate or inhibit the onset of programmed cell death through the manipulation of a variety key apoptotic proteins. This seminar provides the overview of main viral strategies to inhibit the apoptotic death of the host and thus ensure the infected cell survival for the appropriate length of time in order to propagate and successfully transmit to the next host – from expressing viral Bcl-2 homologues to viral gene products that are able to interfere with cell cycle and oxidative stress regulation, control the transcription of apoptosis-related genes, influence the signaling mediators presentation on the cell surface and caspase activation

Morphological and genetic diversity of populations of the invasive crayfish Pacifastacus leniusculus (Dana, 1852) in Croatia

Signalni rak (Pacifastacus leniusculus) je autohton za područje Sjeverne Amerike. Introduciran je na područje Europe i Japana, ali se ubrzo nakon unošenja proširio kao invazivna vrsta. U Hrvatskoj je rasprostranjen u rijekama Muri i Korani gdje je u kompeticiji s autohtonim vrstama te je prijenosnik patogena (Aphanomyces astaci); uzročnika bolesti koja je smrtonosna za autohtone vrste rakova. Budući da se malo zna o genetičkoj raznolikosti vrste, u ovom istraživanju su korišteni mikrosatelitni lokusi i mitohondrijski geni za 16S rRNA s ciljem utvrđivanja međusobnih filogenetskih odnosa proučavanih populacija kao i njihova odnosa prema već istraženim populacijama ove vrste u svijetu. Analizirane su i morfometrijske značajke kako bi se utvrdilo postoje li značajne razlike između populacija i podudaraju li se rezultati morfometrijskh analiza s rezultatima genetskih analiza. Rezultati pokazuju da je raznolikost signalnog raka nešto veća u rijeci Muri, nego u Korani, ali niti jedna metoda jasno ne odvaja dvije populacije. Raznolikost na razini Hrvatske nešto je manja u odnosu na već istražene skandinavske i zapadnoeuropske zemlje. Rezultati ovog rada također pridonose spoznajama o ovoj vrsti kao i procjeni njezinog invazivnog uspjeha.Signal crayfish (Pacifastacus leniusculus) is a native to North America. It was introduced to Europe and Japan but it soon spread as an invasive species. In Croatia, it is widespread in the rivers Mura and Korana where it competes with native spieces. Moreover, it may be an Aphanomyces astaci carrier, a pathogen causing a disease lethal to native crayfish spieces. Since the knowledge on the genetic diversity of this species is limited, microsatellite markers and mitochondrial gene 16S rRNA analyses were used to explore the phylogenetic relations among Croatian populations as well as their relation to other already studied populations. Morphometric characteristics were studied to determine if there are significant differences among populations and if these are concordant with the genetic analyses results. Results showed that the genetic diversity of Pacifastacus leniusculus is slightly higher within the Mura population compared to the Korana population, but no clearly seperation of these two populations wer obtained. Genetic diversity of this species within Croatia is slightly lower in comparison to already investigated Scandinavian and West European countries. This study contributes to the knowledge on signal crayfish, its characteristics, genetic diversity as well as the possible estimation of its invasive success

Marine mammals of the Adriatic sea

Morski sisavci su sisavci dobro prilagođeni na život u morskoj vodi. Oni uključuju kitove i perajare, sirene, morske vidre i polarnog medvjeda. U Jadranu je zabilježena prisutnost ukupno 9 vrsta kitova. Ipak, samo dvije vrste su trajno obitavale tamo do 1970. godine – obični i dobri dupin. Danas su obični dupini izuzetno rijetki jer su bili u kompeticiji za plavu ribu te su postajali žrtve namjernog ubijanja. Dobri dupin (Tursiops truncatus) je jedina vrsta koja i danas trajno živi u Jadranskom moru. Međutim, postoje i bilješke o zapažanju velikog kita, ulješure, glavatog, prugastog, krupnozubog, bijelogrlog i crnog dupina. Oni se smatraju povremenim posjetiocima. Sredozemna medvjedica je jedina vrsta tuljana koja živi u ovom području, ali je također veoma rijetko u današnje vrijeme. Prema IUCN – ovoj crvenoj listi vrsta je pred izumiranjem i statusom je kritično ugrožena. Morski sisavci općenito su ugroženi bukom, kemijskim onečišćenjem, klimatskim promjenama, pretjeranim izlovom ribe i degradacijom staništa. Mnogi od njih su ugroženi i nalaze se pod zaštitom različitih zakona, kako na nacionalnoj razini, tako i kao dio europskih i internacionalnih sporazuma i direktiva.Marine mammals are mammals well adapted for life in the marine environment. They include Cetaceans and Pinnipeds, sea cows, sea otters and the polar bear. Nine cetacean species have been reported to occur in the northern Adriatic Sea. However, only two species were considered regular there until the 1970s: the short-beaked common dolphin and the common bottlenose dolphin. Common dolphins are now extremely rare in this region. It was perceived as competition for the declining blue fish population which led to killing them on purpose. The common bottlenose dolphin, Tursiops truncatus is the only cetacean species regularly reported in the area at the present time. However, striped dolphin, long – finned pilot whale, false killer whale, risso's dolphin, Cuvier's beaked whale, sperm whale and fin whale have been noticed too. They are just visitors here. Mediterreanean monk seal is the only seal living in this area but it is also very rare nowadays. According to the IUCN Red List from 2008, this species is facing extinction, with a status of critically endangered (CR). Marine mammals are threatened by noise and chemical pollution, climate changes, fisheries and habitats loss. Many of them are really endangared and have their places in many laws on nature or sea protection; not only on the national ones but also in European and international agreements and directives

Electrochemical Determination of Metallothioneins by the Modified Brdička Procedure as an Analytical Tool in Biomonitoring Studies

Present study aims to improve the modified Brdička procedure of metallothionein (MT) quantification in a way to reduce the analysis duration. Therefore, scan rate of the voltammetric sweep was increased from 0.0052 V s–1 to 0.013 V s–1 by lowering the duration of one step potential from 0.5 s to 0.2 s, which resulted in 2.5 times faster voltammetric sweep. Research confirmed high accuracy and reliability of MT measurements, in both standard sample and samples of heat-treated cytosols of liver, gills and the intestine of European chub and liver of brown trout. The method was confirmed as fast and reliable electrochemical technique for quantification of MTs and this time-saving improvement is especially useful and applicable in different biomonitoring studies which require the analyses of numerous biological samples and high sample throughput. This work is licensed under a Creative Commons Attribution 4.0 International License

Comparison of electrochemically determined metallothionein concentrations in wild freshwater salmon fish and gammarids and their relation to total and cytosolic metal levels

Application of metallothionein (MT) as an early warning sign of metal exposure in aquatic organisms is common in biomonitoring, but there is a huge variability in MT concentrations among different studies. Present research aims to assess MT responses in freshwater fish brown trout (Salmo trutta Linnaeus, 1758) and gammarids(Gammarus balcanicus Schäferna, 1922 and Echinogammarus acarinatus Karaman, 1931) as indicators of metal exposure within the freshwater karst environment (Krka River, Croatia). Sampling was performed upstream (reference site) and downstream (anthropogenically impacted site) of the wastewater discharges in autumn and spring seasons. Brown trout intestine was applied as a bioindicator tissue due to its role in dietborne metal uptake while gammarids were chosen as fish food and potential metal uptake source. Moreover, there is a lack of data on intestinal MT levels, so our results on MT and metal/metalloid concentrations, measured as total and metabolically available cytosolic levels, represent the first data of this kind for the selected indicator species. The results indicated that the ecotoxicological impact of technological and municipal wastewaters on the biota of the karst Krka River was moderate, although higher metal levels at the affected site were evident in both, fish and gammarids. The modified Brdička reaction applied in this study was confirmed as reliable electrochemical technique for MT quantification in both vertebrates and invertebrates, and it indicated higher MT levels in gammarids (1.9–4.1 mg g−1 w.w) than in fish intestine (0.5–2.8 mg g−1 w.w). Due to the lack of the data on MT concentrations in S. trutta and gammarid species G. balcanicus and E. acarinatus, presented results can serve as a preliminary data to establish MT background levels in intestine of wild freshwater fish and gammarids. Obtained MT levels showed species-, tissue- and method- specific differences, so comparison between MT levels should always involve the same species, tissue and measurement method