Adaptation Of Fish Research Articles

Effects of hypoxia on the gill morphological structure, apoptosis and hypoxia-related gene expression in blunt snout bream (Megalobrama amblycephala).

The blunt snout bream (Megalobrama amblycephala) is a typical hypoxia-sensitive fish, and hypoxia stress leads to reduced vitality and yield during aquaculture. To explore the specific adaptation mechanism under hypoxia, the blunt snout bream was treated with hypoxia (DO = 2.0 ± 0.1mg/L) for 24h, followed by 3h of recovery. Our results depicted that the gill filament structure of blunt snout bream changed after hypoxia. During hypoxia for 24h, the gill filament structure was altered, including a more than 80% expansion of the lamellar respiratory surface area and a proportionate apoptosis decrease in interlamellar cell mass (ILCM) volume. Thus, the water-blood diffusion distance was shortened to less than 46%. During hypoxia for 24h, the activity of ROS in gill tissue increased significantly (p < 0.05), while the mitochondrial membrane potential decreased significantly (p < 0.05). During hypoxia, mRNA expression level of anti-apoptotic gene Bcl-2 in the gills of blunt snout bream decreased significantly (p < 0.05), while the expression of pro-apoptotic gene Bax mRNA increased significantly (p < 0.05). Thus, the ratio of Bax/Bcl-2 mRNA increased in the gills of blunt snout bream to promote the activity of Caspase-3. Together, our results indicated hypoxia-induced apoptosis in the gills of blunt snout bream through the mitochondrial pathway. In addition, a decreased expression of Phd1 and an increased expression of Hif-1α in gills under hypoxia stress indicates that blunt snout bream may cope with hypoxia-induced apoptosis by enhancing the HIF pathway. These results provide new insights into fish's adaptation strategies and mechanisms of hypoxia.

Intestinal bacteria diversity of suckermouth catfish (Pterygoplichthys pardalis) in the Cd, Hg, and Pb contaminated Ciliwung River, Indonesia

The contamination of aquatic environments with heavy metals poses a serious threat to fish, potentially leading to diseases or even death. Therefore, there is an urgent need for studies to investigate the adaptability of fish in heavy metal-contaminated environments. Several studies have explored the adaptability of suckermouth catfish (P. pardalis) to survive in the contaminated Ciliwung River. The findings obtained showed that the presence of intestinal bacteria helped these fish overcome the heavy metals in their intestines, thereby enabling the fish to survive. Analysis using the Next Generation Sequencing (NGS) technology has succeeded in identifying diversity of these bacteria in P. pardalis living in the Ciliwung River, which contaminated with Cd (0.3–1.6 ppm in the water & 0.9–1.6 ppm in the sediment), Hg (0.6–2 ppm in the water & 0.6–1.8 ppm in the sediment), and Pb (59.9–73.8 ppm in the water & 26.1–58.6 ppm in the sediment). Diversity index of intestinal bacteria in P. pardalis was relatively high, but it had a negative correlation with the presence of these contaminants. Actinobacteria, Firmicutes, and Proteobacteria were abundant in the intestines of P. pardalis from the upstream to downstream of the river, with an overall abundance range of 15–48%. Furthermore, Mycobacterium along with 6 other genera were identified as core intestinal bacteria. The presence of these bacterial communities in all the samples affected their survival in heavy metals-contaminated rivers. The fish's adaptability to live in this harsh environment indicated that it has the potential to be utilized as a bioremediator of heavy metals in river sediments.

Effect of herbicides and surfactants on enzymes of energy metabolism in European carp

&lt;p&gt;The effect of herbicides (2,4-D, Roundup, Senkor) and surfactant sodium lauryl sulfate (pure and as part of detergents) on enzymes of energy pathways in the scaly carp's body was studied. Gills, brain, liver and white muscle were selected for the analysis. To determine the levels of activity of enzymes in energy metabolism, lactate dehydrogenase (EC 1.1.1.27) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) in the cytoplasmic fraction and isocitrate dehydrogenase (EC 1.1.1.42) in the mitochondrial fraction were studied. The research found that sodium lauryl sulfate, both pure and in a synthetic detergent, increase the activity of enzymes in all experimental groups. Effect of herbicides was ambiguous. Under the influence of Sencor the activity of enzymes increases in all tissues. Roundup causes inhibition of enzymes in the brain, but there is an increase in the activity of enzymes in other tissues under the influence of this toxicant. The influence of 2,4-D causes increased activity of isocitrate dehydrogenase in all experimental groups, as well as the activity of lactate dehydrogenase in the brain and the liver increases, whereas in gills and white muscle it decreases. The activity of glucose-6-phosphate dehydrogenase by the impact of 2,4-D was decreased only in the liver, in other groups - was increased. The investigations may be evidence of adaptive alterations in energy metabolism aimed at the survival of fish under conditions of herbicides and surfactants toxic effects. Also increase the activity of enzymes can be related to detoxification processes occurring in the body and require additional energy consumption. The article presents the results of the study of the influence of herbicides (2,4-D, Zenkor, Roundup) and surfactant the sodium laurylsulfate (pure and as a part of the synthetic detergent) on the activity of lactate dehydrogenase, isocitrate dehydrogenase, glucose-6-phosphate dehydrogenase in the liver, gills, brain and white muscle of scaly carp (&lt;em&gt;Cyprinus carpio&lt;/em&gt; L.). Human impact on water forcing fish to use various mechanisms of adaptation to the changed environmental conditions. Knowledge about the features of the receipt, distribution, accumulation of xenobiotics in organs and tissues, biochemical changes as a result of poisoning can be used to find out the mechanisms of fish's adaptation to toxicants, for identify the causes of death of hydrobionts in natural waters and to justify methods of controlling environmental pollution. The results of the research show that the influence of herbicides and surfactants causes significant changes in the processes of energy metabolism of scaly carp.&lt;/p&gt;

Learning Control for Biomimetic Undulating Fins: An Experimental Study

Learning control should focus on imitating natural fish's adaptability to complex and dynamic environment to some extent, rather than mimicking streamlined shapes or specific actuators to develop more mechanical prototypes. In this paper, an experimental study on a proposed learning control of the robotic undulating fin, RoboGnilos, is suggested and explored. This study takes inspirations from biological world to practical control algorithms. In detail, an iterative learning scheme based control is studied with the cooperation of a filter to reduce the measurement noise, and a curve fitting component to keep the necessary phase difference between neighboring fin rays. Moreover, the iterative learning control algorithm is designed and implemented for practical applications. The experimental results validate that the proposed learning control can effectively improve the propulsion of RoboGnilos. For instance, the steady propulsion velocity may be enhanced by over 40% with some specified parameters.

The histological structure of the upper and lower jaw teeth in the gobiid fish, Sicyopterus japonicus.

The histological structure of upper-and lower-jaw teeth of Sicyopterus japonicus, a fish known to exhibit rock-climbing behavior, were examined by light microscopy and scanning electron microscopy.The upper jaw teeth and the lower jaw teeth were entirely different in form. The characteristics of the upper jaw teeth were that the enameloid constituting the tip of the tooth had a shovel-like shape and that there were many eruptive teeth behind each of which lay a large number of successional teeth ready for continuous replacement. The shape of the enameloid was suited to the work of scraping algae from the surface of stones. The lower jaw teeth had a hinged structure.It was suggested that the forms of teeth in Sicyopterus japonicus were the result of the fish's adaptation to its feeding habit, rather than its rock-climbing nature.