Sema İşisağ Üçüncü

Apoptosis in fish: environmental factors and programmed cell death

Apoptosis, a form of programmed cell death, is a critical component in maintaining homeostasis and growth in all tissues and plays a significant role in immunity and cytotoxicity. In contrast to necrosis or traumatic cell death, apoptosis is a well-controlled and vital process characterized mainly by cytoplasmic shrinkage, chromatin condensation, DNA fragmentation, membrane blebbing and apoptotic bodies. Our understanding of apoptosis is partly based on observations in invertebrates but mainly in mammals. Despite the great advantages of fish models in studying vertebrate development and diseases and the tremendous interest observed in recent years, reports on apoptosis in fish are still limited. Although apoptotic machinery is well conserved between aquatic and terrestrial organisms throughout the history of evolution, some differences exist in key components of apoptotic pathways. Core parts of apoptotic machinery in fish are virtually expressed as equivalent to the mammalian models. Some differences are, however, evident, such as the extrinsic and intrinsic pathways of apoptosis including lack of a C-terminal region in the Fas-associated protein with a death domain in fish. Aquatic species inhabit a complex and highly fluctuating environment, making these species good examples to reveal features of apoptosis that may not be easily investigated in mammals. Therefore, in order to gain a wider view on programmed cell death in fish, interactions between the main environmental factors, chemicals and apoptosis are discussed in this review. It is indicated that apoptosis can be induced in fish by exposure to environmental stressors during different stages of the fish life cycle.

Environmental pollution and toxic substances: Cellular apoptosis as a key parameter in a sensible model like fish

The industrial wastes, sewage effluents, agricultural run-off and decomposition of biological waste may cause high environmental concentration of chemicals that can interfere with the cell cycle activating the programmed process of cells death (apoptosis). In order to provide a detailed understanding of environmental pollutants-induced apoptosis, here we reviewed the current knowledge on the interactions of environmental chemicals and programmed cell death. Metals (aluminum, arsenic, cadmium, chromium, cobalt, zinc, copper, mercury and silver) as well as other chemicals including bleached kraft pulp mill effluent (BKME), persistent organic pollutants (POPs), and pesticides (organo-phosphated, organo-chlorinated, carbamates, phyretroids and biopesticides) were evaluated in relation to apoptotic pathways, heat shock proteins and metallothioneins. Although research performed over the past decades has improved our understanding of processes involved in apoptosis in fish, yet there is lack of knowledge on associations between environmental pollutants and apoptosis. Thus, this review could be useful tool to study the cytotoxic/apoptotic effects of different pollutants in fish species.

A histological study on the ventricle of convict cichlid, Amatitlania nigrofasciata (Günther, 1867)

Bu calismada zebra ciklit ( Amatitlania nigrofasciata ) ventrikulunun morfolojik ve histolojik ozellikleri isik mikroskobu ile incelenmistir. Ventrikul, piramit bicimlidir ve ventrikul duvari epikardiyum, miyokardiyum ve endokardiyum tabakalarindan meydana gelmistir. Epikardiyum ve endokardiyum tek katli yassi epitel ile ince bir bag dokudan olusmustur. Daha kalin bir tabaka olan miyokardiyum, kolayca ayirt edilebilen iki tabaka halinde izlenmistir; dis tabaka, siki sekilde organize olmusken ic tabaka, dallanmis kalp kasi demetleri arasinda yer alan iri trabekulleri ile sungerimsi gorunume sahiptir. Ventrikulun piramidal bicimi ve kas duzenlenisi metabolik aktivitenin onemli bir parametresi olarak degerlendirilerek tartisilmistir.

An Investigation on Some Toxic Effects of Carbofuran on Daphnia magna (Crustacea, Cladocera)

Bu çalışmada karbamatlı bir pestisit olan karbofuran’ın Daphnia magna için EC50 değerinin bulunması ve kalp atım sayısı üzerindeki etkilerinin belirlenmesi amaçlanmıştır. Denemede negatif kontrol, çözücü kontrol (aseton) ve uygulama grupları için beşer daphnid (24 saatlikten küçük) kullanılmıştır. Uygulama grupları karbofuran’ın (% 98 saflıkta) beş farklı derişimine (2.5 μg/L, 4.5 μg/L, 8.1 μg/L, 14.58 μg/L ve 26.24 μg/L) 48 saat boyunca maruz bırakılmıştır. Tüm gruplarda 24. ve 48. saatlerde hareketsiz bireyler kaydedilmiş ve probit analiz yöntemi ile EC 50 değerleri sırasıyla 33.814 μg/L ve 3.451 μg/L olarak hesaplanmıştır. 48 saat sonunda, tüm örnekler ışık mikroskobu ile incelenmiş ve bir dakikadaki kalp atım sayıları video kamera ile kaydedilerek belirlenmiştir. Kalp atım sayıları negatif kontrol grubunda 444.8±24.12; çözücü uygulanan kontrol grubunda ise 458.4±34.14 olarak birbirine yakın değerlerdedir. Deneme gruplarında bu sayılar artan derişimine göre sırasıyla 2.5 μg/L için 498.4±17,43; 4.5 μg/L için 183.8±103.83; 8,1 μg/L için 441.6±35.73; 14.58 μg/L için 293.8±101.09 ve 26.244 μg/L için 442.4±32.94 olarak kaydedilmiştir. Buna göre karbofuran, D. magna neonatlarında hareketsizliğe ve kalp atım sayılarında azalmaya sebep olmuştur; ancak bu azalma derişim artışı ile paralellik göstermemektedir.

The effects of Dioctyl Adipate (DOA) on liver and gill histology of Sparus aurata ( Sea Bream).

Although it is used widely as a second plasticizer in the polymer manufacturing process, the ecotoxicological effects of dioctyl adipate (DOA) was not investigated in detail. The aim of this research was to determine the histopathological changes in the gills and liver of male sea bream, Sparus aurata exposed to 250, 500 and 750 ppm DOA for 15 days, with light microscopy. When compared with control, remarkable histopathological changes as vacuolation, dilatation of the central vein, and a striking fusion were observed in the gills of experimental fish. It was also noted hypertrophy and hyperplasia in the epithelial, pillar, mucoid and mitochondria-rich cells of the gills. The examining of livers from DOA-exposed specimens revealed a series of hepatocellular changes, including steatosis, necrosis and fibrosis. In addition to haemorrage, the parenchimatic sinusoids and the central veins of hepatopancreas were widened. The study demonstrated that the exposure to DOA results in multiple histological changes in both of the tissue investigated; moreover, all of the changes were associated with increasing concentration of the chemical that exposed. Consequently, it was emphasized that DOA needs to be taken into more consideration as being an aquatic ecotoxicant.