Water Permeability of the Gill Epithelium: Salinity and Temperature Relations
Gheorghe Benga in Water Transport in Biological Membranes, 1989
It is now recognized that the complex structure of gills, in particular fish gills, does not allow for the treatment of water exchanges as diffusion across a homogeneous membrane. There may be functional separation of the gas and ion exchange areas in a gill. In fish, the osmoregulatory chloride cells are virtually restricted to the primary lamellae. There are functional differences between anterior and posterior gills in crabs, where ion-transporting cells (10 to 20 μm thick) are concentrated in patches on posterior gill pairs interspersed with the flattened respiratory cells (1 to 2 μm thick) common to every gill pair.33,34 The simple lamellar gills of amphipod crustaceans are composed of a single, multifunctional type of cell.35 The functional vascularization of the fish gill has now been described, allowing for separation of the fluxes across the respiratory and nonrespiratory epithelium,20 i.e., the secondary lamellae, representing the greater part (≃96%) of the exchange surface and the primary lamellae (≃4% of the exchange surface), respectively. It has been established for gill tissue exhibiting regional specialization of function that water exchanges occur principally through the respiratory cells. The branchial respiratory epithelium is composed of flat cells which in most cases are linked by deep intercellular junctions, and it is suggested that the cell membranes, rather than these tight junctions, are the limiting factor of branchial water permeability (i.e., water traverses the gill by a transcellular route).20
Animal Source Foods
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
Anatomically, there is no difference between saltwater fish and freshwater fish. Both saltwater and freshwater fish breathe through specialized gills, which are openings located on their skin (23). The main difference resides in the regulation of salt and water contents in their tissues by osmosis in order to maintain the ratio of salt and water levels constant with their water environment – saltwater or freshwater. Freshwater fish have gills that function to diffuse water while ensuring bodily fluids remain inside the fish (23). Freshwater fish have large, well-developed kidneys that are able to process large amounts of urine in order to avoid an excess of water in their body tissues (23). Saltwater fish lose large quantities of internal body fluids through their gills because of osmosis. Since saline water is less diluted than the internal fluids of the fish, the saline water rushes in to replace the internal fluids in an effort to form an equilibrium. They replace lost water by consuming large quantities of saltwater (23).
Anatomy of the Heart and Circulation
Wilmer W Nichols, Michael F O'Rourke, Elazer R Edelman, Charalambos Vlachopoulos in McDonald's Blood Flow in Arteries, 2022
As mentioned, fish have a single ventricle that pumps blood through the gills where oxygenation occurs, up to the dorsal aorta whence it passes through systemic arteries to all parts of the body. Other cold-blooded animals, such as turtles, frogs and snakes, also have a single ventricle but have separation of oxygenated and deoxygenated blood within the ventricle before passage under pressure into the lungs and aorta (Harrison, 1965; Stephens et al., 1983; Zimmer, 1998, 2004; Leite et al., 2013; Skovgaard et al., 2018). Such animals were used to study cardiac activity in the distant past since their slow heart rate (30/minute) enabled movements to be recorded adequately with the low-frequency mechanical equipment of the day and the absence of a membranous ventricular septum allowed for cannulation of the vena cava for input and the aorta for output control. The pulmonary vessels could be tied off without interrupting a complete circuit but not without consequence. Remarkably, the form and shape of the ventricles allowed for directed flow from the right ventricle to the pulmonary artery and left ventricle (LV) to the aorta with minimal (~12 percent) mixing but the ventricle operated at different pressures. Bypassing the pulmonary circuit forced blood from the right ventricle to the aorta and could well explain why at high volumes the Frank–Starling curve tails off as right ventricular walls may be over-distended. In Otto Frank’s classic frog heart preparations, the peripheral circulation was cut open so that the filling of the ventricle (preload) could be regulated independently of afterload (Zimmer, 2004).
Manganese dioxide nanosheets induce mitochondrial toxicity in fish gill epithelial cells
Published in Nanotoxicology, 2021
Cynthia L. Browning, Allen Green, Evan P. Gray, Robert Hurt, Agnes B. Kane
The gills are highly metabolically active organs that regulate gas exchange and ionic homeostasis (Dawson et al. 2020). Mitochondrial activity is important for providing adequate energy in the form of ATP at basal levels and in response to stress. The ability to respond to external stress, such as a predator or alterations in salinity or water temperature, are crucial for fish survival. Impairment of mitochondrial function, particularly inhibition of basal mitochondrial respiration, maximal respiration and spare respiratory capacity, reflects severe damage to this vital organ. Prolonged gill dysfunction would be lethal to the individual. Our observations suggest that MnO2 nanosheet exposure would severely impair mitochondrial function within the gill tissue, which would likely result in fish death.
Splenectomy in zebrafish: a new model for immune thrombocytopenia
Published in Platelets, 2022
Uvaraj P Radhakrishnan, Ayah Al Qaryoute, Revathi Raman, Pudur Jagadeeswaran
Splenectomy was performed on larger vertebrates, including rainbow trout [23,24]. However, it is difficult to use such animals in laboratory research. Although zebrafish is approximately 1.5 inches long, since the internal organs, particularly spleen, get entangled among the other organs, this twisting makes it challeng to remove the spleen and is not a trivial undertaking. Thus, splenectomy had to be performed under a stereomicroscope. In addition, the fish had to be kept alive by pumping water over the gills, so ventilation is facilitated. This modification is important for laparotomy in zebrafish. Since anesthesia does not last more than 10 minutes in zebrafish, the surgery had to be performed within that period. Furthermore, since the spleen is so small using scissors to cut, it may result in organ damage. Thus, the unique pulling technique was introduced. Pulling any small debris is usually used in surgery. The lack of severe bleeding is probably due to the fact that fish blood clots faster than human blood.
Trophic transfer, bioaccumulation, and potential health risk of trace elements in water and aquatic organisms of Yundang Lagoon at Xiamen in China
Published in Toxin Reviews, 2023
Mohammad Mazbah Uddin, Guogan Peng, Lingfeng Huang
Water samples were collected from 13 sampling sites including the inlet channel, inner lagoon, and outer lagoon in Yundang Lagoon during July 2019 (Figure 1, Supplementary Table S1). Water sample collector (S8245, China) was used to collect the water sample from the lagoon and stored in nitric acid (Merck Millipore, Germany) (5%) washed polyethylene bottles. From each sampling site, triplicate water samples were collected. Aquatic organisms such as fishes, crabs, prawns, and mollusks were collected by multi-gillnet on July 2019. The gill nets were set at the center of each selected site for 24 h with 1 m height and 90 m long consisting of two panels of different mesh sizes (3 and 15 cm). Three species of fish Oreochromis niloticus, Platycephalus indicus, Clupanodon punctatus, and three species of crab Charybdis japonica, Portunus sanguinolentus, Charybdis varuegata were collected from the lagoon with the number of samples 37, 8, 11, 7, 10, and 4, respectively. Besides, four prawn species Litopenaeus vannamei, Metapenaeus joyneri, Penaeus japonicas, and Penaeus penicillatus, and two mollusk species Mytilus spp. and Perna spp. were also collected from the lagoon with the number of samples 22, 18, 9, 3, 6, and 8, respectively. Aquatic organisms were put in a ziploc plastic bag and stored at 4 °C until arriving in the laboratory.