Response to cobalt toxicity in lichen Pseudevernia furfuracea; uptake, photosynthetic quantum yield, membrane integrity and deoxyribonucleic acid fragmentation

Öz

Objectives: This study aims to examine the toxic potential of Cobalt (Co) on photosystem II photosynthetic quantum yield, membrane integrity, and deoxyribonucleic acid (DNA) fragmentation formation.

Materials and methods: Oligonucleosomal DNA fragmentation was detected by terminal deoxynucleotidyl transferase-dUTP nick end labeling (TUNEL) assay. Lipid peroxidation was determined with malondialdehyde analyzing.

Results: The Fv/Fm ratio decreased in Pseudevernia furfuracea following exposure to various concentrations of Co (NO3)2 (5, 15 and 30 mM) for one, three and 24 hours. Co2+-treatment caused the accumulation of Co in lichen, induced severe oxidative stress by the generation of hydrogen peroxide, impaired the membrane integrity, and induced lipid peroxidation as measured by malondialdehyde. Samples treated with 15 mM and 30 mM of Co (NO3)2 had higher percentage of cell death than 5 mM-treated group.

Conclusion: To our knowledge, this is the first study detecting a high rate of DNA fragmentation in situ in phycobiont layer of Pseudevernia furfuracea; while it reveals that mycobiont layer has a lower rate of TUNEL-positive cells. It has been concluded that Co exposure results in impaired photosynthesis accompanied by oxidative stress and DNA fragmentation in Pseudevernia furfuracea; all these effects were concentration-dependent.

Anahtar Kelimeler

• Cobalt
• deoxyribonucleic acid fragmentation
• lichen
• oxidative stress
• Pseudevernia furfuracea
• TUNEL

Pseudevernia furfuracea’da kobalt toksisitesine yanıt; alım, fotosentetik kuantum verimi, membran bütünlüğü ve deoksiribonükleik asit fragmantasyonu

Öz

Amaç: Bu çalışmada fotosistem II fotosentetik kuantum verimi, membran bütünlüğü ve deoksiribonükleik asit (DNA) fragmantasyonu formasyonu
üzerinde kobaltın (Co) toksik potansiyeli incelendi.
Gereç ve yöntemler: Oligonükleozomal DNA fragmantasyonu terminal deoksinükleotidil transferaz dUTP çentik uç işaretleme (TUNEL) testi ile tespit
edildi. Lipid peroksidasyonu malondialdehit analizi ile belirlendi.
Bulgular: Bir, üç ve 24 saat boyunca farklı Co konsantrasyonlarına (NO3)2 (5, 15 ve 30 mM) maruziyetten sonra Pseudevernia furfuracea’da Fv/Fm
oranı azaldı. Co2+-tedavisi likende Co birikimine yol açtı, hidrojen peroksit üretimi ciddi oksidatif stres başlattı, membran bütünlüğüne zarar verdi ve
malondialdehit ile ölçüldüğü üzere lipid peroksidasyonu oluşturdu. On beş mM ve 30 mM Co (NO3)2 ile tedavi edilen örneklerin hücre ölümü yüzdesi
5 mM ile tedavi edilen gruptan daha yüksek idi.
Sonuç: Bildiğimiz kadarıyla, bu çalışma Pseudevernia furfuracea’nın fikobiont katmanında in situ yüksek oranda DNA fragmantasyonu tespit ederken
mikobiont katmanda daha düşük oranda TUNEL pozitif hücre olduğunu gösteren ilk çalışmadır. Kobalt maruziyetinin Pseudevernia furfuracea’da
oksidatif stres ve DNA fragmantasyonunun eşlik ettiği bozulmuş fotosenteze yol açtığı sonucuna varıldı; tüm bu etkiler konsantrasyona bağımlı idi.

Anahtar Kelimeler

• Kobalt
• deoksiribonükleik asit fragmantasyonu
• liken
• oksidatif stres
• Pseudevernia furfuracea
• TUNEL

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