The expression levels of virulence and antibiotic resistance genes in Lactococcus garvieae exposed to different conditions.

Lactococcus garvieae, baliklarin hemorajik septisemisi olan laktokokkozun etken maddesidir. Laktokkoz, ticari açidan önemli birçok tatli su ve deniz türünü etkiledigi için su ürünleri yetistiriciliginde önemli ekonomik kayiplara neden olur. Bu çalismada çalismada kullanilan bakterilerin biyokimyasal testlerde %92,5 oraninda tespit edildigi görülmüstür. Çalismada kullanilan L. garvieae etkeninin Gentamisin, Tobramisin, Sefoksitin, Penisilin G, Amoksisilin-Klavulanat, Trimetoprim-Sülfametoksazol, Klindamisin, Fusidik Asit ve Rifampine dirençli oldugu da gözlendi . L. garvieae etkeninin optimum büyüme sicakligi 21 o alindigindaC'de kontrol grubu için virülans gen ekspresyon düzeyi ajanin en iyi gelisebilecegi sicaklik araligi olan 25 ve 37°C'de yukari, 15°C ve 45°C'de ise asagi yönlü düzenlenmistir. Benzer sekilde 25°C'ye en yakin sicaklikta üreyen bakterilerde gen ekspresyon düzeyinin antibiyotik direnç geni ekspresyon düzeyinde 21°C kontrol grubuna göre, bakterilerin ekspresyon düzeylerinde ise anlamli düzeyde yukari regüle oldugu gözlendi. diger sicakliklarda büyüme daha düsüktü. Bu sonuçlar dikkate alindiginda, çalismada kullanilan bakteri gökkusagi alabaligindan izole edildiginden, sicakligin virülans üzerindeki etkisinin önemli ölçüde etkili oldugu anlasilmaktadir.

Determination of Antimicrobial Resistance Gene Variations Using Tet and Str Genes in Freshwater Fish Species.

With the rapid development of aquaculture, antibiotics are widely used for prophylactic and therapeutic purposes to reduce economic losses caused by disease outbreaks. Considering that most antibiotics applied to humans and animals are partially metabolized and not eliminated, it is evident that these antibiotic residues can have negative effects on natural aquatic organisms after reaching the receiving environment, such as rivers and reservoirs. Therefore, it is believed that this indiscriminate use of antibiotics is now beginning to affect aquatic organisms in natural environments, outside of closed environments. In this study, tissue samples were taken from seven fish species in the Firat River. Specific primer sets were designed for Tet and Str genes, which are known to play a role in antibiotic resistance mechanisms. The changes in gene expression levels were then examined. The results showed that the expression levels of Tet and Str genes associated with antibiotic resistance were more than two-fold higher in Cyprinus carpio and Chondrostoma regium species compared to a control group that did not use antibiotics. A moderate expression level was observed in Capoeta trutta, Acanthobrama marmid, Capoeta umbla, and Barbus grypus species. In addition, in Luciobarbus mystaceus species, the Tet gene was expressed at a meaningless level, while the Str gene was downregulated. Therefore, it is believed that this species may not have encountered or has previously encountered antibiotics at low levels, leading to the control levels of the resistance mechanism.

Effects of prolonged fasting on levels of metabolites, oxidative stress, immune-related gene expression, histopathology, and DNA damage in the liver and muscle tissues of rainbow trout (Oncorhynchus mykiss).

This study was conducted to assess the impacts of prolonged fasting (70 and 120 days) on the morphological, biochemical, oxidative stress responses, immune-related gene expression, histopathology, and DNA damage in rainbow trout. Final weight (FW), hepatosomatic index (HSI), and condition factor (CF) significantly decreased in both 70 and 120 days of fasting compared to the pre-fasting group (p < 0.05). Fasting led to a significant reduction in serum blood metabolites (glucose, total protein, triglyceride, T. cholesterol, high-density lipoprotein (HDL), and low-density lipoprotein (LDL)) and endogenous reserves (protein and lipid). However, plasma acetylcholinesterase (AChE) activity, aspartate aminotransferase (AST), alanine aminotransferase (ALT), interleukin (IL1), tumor necrosis factor (TNF1α), and transferrin (TF) increased significantly (p < 0.05). While malondialdehyde (MDA) levels compared to the pre-fasting group increased in the liver and muscle tissues (70 and 120 days), glutathione (GSH) enzyme activities decreased significantly in both tissues (p < 0.05). Histopathologically, both fasting groups (70 and 120 days) when compared to the pre-fasting group led to steatosis, necrosis and degeneration in hepatocytes, inflammation and hyperemia in the liver tissue and hyaline degeneration, atrophy, and inflammation in muscle tissue. Additionally, 8-OHdG levels of the liver and muscle tissues at 120 days' fasting were more severe according to 70 days' fasting. Finally, blood, the liver, and muscle tissues may be helpful to assess the impacts of fasting and fasting stress in rainbow trout.

Effects of different LED light spectra on rainbow trout (Oncorhynchus mykiss): in vivo evaluation of the antioxidant status.

Rainbow trout (Oncorhynchus mykiss) farming is one of the major aquacultures in Turkey. Some conditions in fish farming can induce oxidative stress leading to the deterioration in properties such as appearance/color, texture, and flavor in fish meat. This situation may cause the consumer not to prefer edible fish. Although there are some studies on the impacts of light intensity on fish welfare, the changes in the antioxidant enzyme activities have not been elucidated. In the current study, it was intended to examine in rainbow trout how cultivating under different wavelengths affects the antioxidant enzymes and acetylcholine esterase (AChE) activity, because its activity is associated with oxidative stress, and also the determination of which light is suitable for fish welfare was aimed. Rainbow trout larvae were grown under four lights with different wavelengths: natural sunlight and incandescent long-wave (red light), medium-wave (green light), and short-wave (blue light) LED light. The experiment lasted for 64 days. Biochemical assays were carried on in the brain, gill, and liver of rainbow trout. Antioxidant enzymes and AChE activity, which play an important role in the central nervous system, were assayed. In gill tissues, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glucose 6 phosphate dehydrogenase (G6PD), glutathione reductase (GR), glutathione S-transferase (GST), and AChE activities increased under all three light wavelengths. In the liver, while activities of antioxidant enzymes and AChE decreased in red light, all of them increased in blue and green light. In the brain, GPx, GST, G6PD, and SOD activities were reduced but AChE activity did not alter under all three light sources. In conclusion, light sources with different spectral structures caused important changes in the activities of antioxidant enzymes in rainbow trout. On this basis, it may be thought that this may be a response to the changing redox status of a cell. Based on our results, blue light sources may be suggested for fish welfare in rainbow trout culture, and providing fish welfare by changing light sources can be easy and cheap in fish farming.

The effects of light sources with different spectral structures on ocular axial length in rainbow trout (Oncorhynchus mykiss).

Every day, we are acquiring more and more clues regarding the effects of different spectral structures (SS) of light on ocular axial length (OAL). As a step towards understanding this association, this study sought to characterise the effects of light sources of different SS on OAL in fish through comparisons with indoor daylight. The experimental design was completely randomised with 4 treatments and 2 replications. Three hundred and fifty two rainbow trout (Oncorhynchus mykiss) were housed in 8 tanks and fed for 71 days. Differences in the mean values of ocular elongation were determined at the end of the experiment. The daylight group was exposed to indoor daylight in the hatchery environment, the red group was exposed to long wavelength light (600-650 nm), the green group was exposed to mid-wavelength light (495-570 nm) and the blue group was exposed to short wavelength light (420-495 nm). The values of the OALs in fish grown under the same light intensity, but with light of different spectral characteristics, demonstrated significant differences (p < 0.05). The mean OAL in the daylight group was determined as 3.64 ± 0.40 mm, as 3.70 ± 0.35 mm in the red group, as 3.53 ± 0.34 mm in the green group and as 3.42 ± 0.29 mm in the blue group. The mean OAL in the blue group was significantly shorter compared to the red (p = 0.003) and the daylight groups (p = 0.02). When compared with the long wavelength light and indoor daylight, the effect of short wavelength light on OAL in fish was observed to be negative. Exposure to light with modified SS of in indoor environments may be effective in stopping ocular elongation.