Which activity produces nitrogenous wastes

Water 3. Protein 5. Enzymes 6. Cell Respiration 9. Photosynthesis 3: Genetics 1. Genes 2. Chromosomes 3. Meiosis 4. Inheritance 5.

Genetic Modification 4: Ecology 1. Energy Flow 3. Carbon Cycling 4. Climate Change 5: Evolution 1. Evolution Evidence 2.

Natural Selection 3. Classification 4. Cladistics 6: Human Physiology 1. Digestion 2. The Blood System 3. Disease Defences 4. The standard curve of each gene was confirmed to be in a linear range with ribosomal protein L7 olrpl7 as a reference gene. The expression of this reference gene has been demonstrated to be stable among ontogenetic stages and during acid-base perturbation treatment in Japanese medaka 37 , Fluorescence signals detected by DIG-labeled RNA probes were enhanced through fluorescein-tyramide signal amplification.

It was an enzyme-mediated detection method to generate high-density labeling of a target nucleic acid. Medaka embryos at the one-cell stage were injected with a 0. Various dosages 0. Glass capillary tubes no. To calibrate the ion-selective probe, the Nernstian response of each microelectrode was evaluated by placing it in a series of standard solutions 0. Before measurement, an anesthetized larva was positioned in the center of the chamber with its lateral side contacting the base of the chamber.

To calculate ionic gradients, the background concentration was subtracted from the concentration at the target position. GraphPad Prism 7.

The metabolic rates of medaka kept under control FW conditions were Effects of salinity on metabolic rates and ammonia excretion. In addition, other carbon cycle-related AAs were as well estimated in this study. Transcript levels of rate-limiting mitochondrial enzymes carbamoylphosphate synthetases CPS in gills for urea synthesis Supplemental Fig.

In addition, ornithine carbamoyltransferase olotc in gills Supplemental Fig. However, Rh proteins were all downregulated in gill tissue upon salinity challenge Fig. Cropped agarose gels original images as shown in Supplemental Fig. S6 show semi-quantitative PCR with cycle amplification of urea cycle-related enzymes, carbamoyl phosphate synthetase olcps1 and olcps2 , ornithine transcarbamylase olotc and the reference gene ribosomal protein L7 olrpl7 in brain, gill, liver, intestine and muscle of adult medaka B.

Overlapping letters indicate that differences are not significant between time points in the treatment group. GLS enzymes are responsible for catalyzing glutamate synthesis Fig. Similarly, glutamate-ammonia ligase GLUL enzymes are responsible for catalyzing glutamine synthesis Fig.

A schematic of the glutamate-glutamine cycle and putative enzymes is shown. A Cropped agarose gels original images as shown in Supplemental Fig.

S6 show semi-quantitative PCR with cycle amplification of glutaminase olgls1a , olgls1b and olgls2 , glutamine synthetase olglul and the reference gene ribosomal protein L7 olrpl7 in brain, gill, liver, intestine and muscle of adult medaka. We further investigated the spatial expression of olgls1a , olgls2 , and olglul in the epithelium of 7 dpf larvae by in situ hybridization.

All three candidate genes showed the salt-and-pepper-like pattern that is typical of ionocytes in the yolk sac epithelium Fig. On the one hand, olgls1a Fig. On the other hand, mRNA expression of olglul Fig.

The inlay figures in A — C are sense probe hybridized images. Glutamate transporters Eaats , olslc1a1 , olslc1a2a , olslc1a2b and olslc1a3 , and glutamine transporters Sats , olslc38a4 and olslc38a5 , were all found to be expressed in medaka gills Fig. Expressions of olslc1a2a and olslc38a4 were comparatively higher in gill tissues than other Eaat and Sat paralogs Supplemental Fig. The glutamate transporter ortholog, Eaat3 encoded by olslc1a1 ; Fig.

Besides, all the Eaat1 encoded by olslc1a3 ; Fig. However, none of the olslc1a2a -expressing cells were also positive for NKA Fig. A schematic model is shown of the glutamate-glutamine cycle and putative transporters.

S6 show semi-quantitative PCR with cycle amplification of glutamate transporters olslc1a1 , olslc1a2a , olslc1a2b and olslc1a3 , glutamine transporters olslc38a4 and olslc38a5a and the reference gene ribosomal protein L7 olrpl7 in brain, gill, liver, intestine and muscle of adult medaka. The inlay figures in A — D are sense probe hybridized images.

Synthetic MO targeting Sat encoded by olslc38a4 was injected into fertilized eggs to knockdown the translation of Sat protein Supplemental Fig. B , Glutamate, a major plasma-derived energetic substrate, is transported to gills in response to salinity challenge. After euryhaline teleosts are acutely exposed to hyperosmotic BW, glutamate and glutamine are accumulated in gills via transport by glutamate transporter Eaats and glutamine transporter Sat.

Glutamine synthetase Glul is activated in energy storage GR cells to convert the glutamate to glutamine. Glutamate is a central molecule in neurotransmission and brain metabolism 42 , It is not only the major excitatory neurotransmitter in the brain, but also serves roles as an energy substrate and protein constituent 44 , Here we elucidate the role of a glutamate-glutamine cycle in the branchial epithelium of teleosts that plays an important role the acclimation capacities to osmotic fluctuations.

It has been well documented that in euryhaline teleosts, acclimation to hyperosmotic SW requires timely activation of ion excretion and water retention mechanisms to maintain osmotic balance. Currently, it is thought that extra-renal organ functions are necessary for euryhaline teleosts to retain a relatively low osmotic concentration of body fluid under hyperosmotic conditions, such as in a marine environment 2 , 46 , 47 , 48 , Therefore, basolateral NKA in the epithelium may be highly important in providing the necessary driving force for ion transport 2.

The increased oxygen consumption may reflect increased energetic demands for the transport of inorganic ions for the maintenance of osmotic homeostasis and was accompanied by an accumulation and retention of organic nitrogenous compounds, such as urea and trimethylamine oxide TMAO. However, gill urea contents determined in the present study was approximately 0. Therefore, it is likely that an enhanced metabolism of nitrogenous organic compounds is primarily employed to fuel osmotic regulation.

Hence, the role of organic nitrogen metabolism in epithelial cells may be critical for the energetic requirements during acclimation to hyperosmotic conditions. Several environmental factors, including salinity and temperature, may affect AA regulation in various fish organs 5 , The rapid accumulation of AAs in fish gill suggests that they are transported to the tissue at a rate greater than the rate of utilization for energy production and protein synthesis.

When AA concentrations in tissue increase, the rate of AA deamination increases as a result. Based on this study, not all the AA contents in gills were found to be responsive to hyperosmotic challenges Supplemental Fig.

Accumulation of glutamate, glutamine and proline was observed in medaka gills after exposure to increased salinity, indicating that these amino acids are available as metabolic substrates for physiological processes under hyperosmotic challenge. In addition, glutamate, glutamine and proline are members of the glutamate family 57 , 58 , which infers that these AAs are easily trans-aminated into glutamate, and glutamate trans-deamination is the main pathway of AA oxidation.

Earlier studies reported that GDH activity and glutamate content were increased in isolated gill epithelial cells of tilapia Oreochromis mossambicus following long-term SW acclimation Bedsides, expression profiles of Eaats and Sats also infer that NKA-labeled epithelial ionocytes may take up extracellular glutamate and glutamine via these specific transporters. The expression patterns of glutamate and glutamine-converting genes, Gls and Glul, were stimulated by BW challenge in gill tissue in a time-dependent manner.

In medaka hatchlings, there are at least two Gls or Glul isoforms expressed in ionocytes or neighboring cells, as shown by NKA-labeling experiments.

Based on the spatial distribution of Gls and Glul in the epithelium of fish yolk sac, we infer that these enzymes may possibly be localized in the energy-storing GR cells of the epithelium, which were proposed to exist in tilapia and zebrafish 2 , 4 , Here it should be noted that despite the very similar overall function and cellular equipment of gill epithelia and the yolk integument 60 , 61 , 62 , 63 we cannot rule out the possibility that there are some differences in gene expression patterns between larval and adult branchial epithelia.

Upon cellular metabolic induction, nitrogenous waste increases in parallel. However, these reactions are not usually considered to occur to a large extent in gill tissue.

Instead, liver was postulated to the major organ for intact ammonia formation and exhibits relatively high GDH activity 59 , Moreover, glutamate catabolism-related enzymes and specialized proteins to facilitate urea movement across the epithelium were also identified in fish gills 67 , 68 , Hence the activation of glutamate family AAs would provide necessary substrates for energy supply, osmotic balance and acid-base regulation 14 , 66 , 69 , 70 , Moreover, the present study suggests that features of a glutamate-glutamine cycle may be commonly derived from epidermal development, since they are found in both neural ectoderm-derived CNS and the non-neural ectoderm-derived gill epithelium in vertebrates.

Evans, D. The multifunctional fish gill: dominant site of gas exchange, osmoregulation, acid-base regulation, and excretion of nitrogenous waste. Hwang, P. Ion regulation in fish gills: recent progress in the cellular and molecular mechanisms.

Physiol , R28—R47 Hirose, S. Molecular biology of major components of chloride cells. B Biochem Mol. Tseng, Y. Glycogen phosphorylase in glycogen-rich cells is involved in the energy supply for ion regulation in fish gill epithelia.

Physiol , R—R Some insights into energy metabolism for osmoregulation in fish. Boeuf, G. How should salinity influence fish growth? Chang, J. Regulation of glycogen metabolism in gills and liver of the euryhaline tilapia Oreochromis mossambicus during acclimation to seawater. Functional analysis of the glucose transporters-1a, -6, and Reshkin, S.

Intestinal glucose transport and salinity adaptation in a euryhaline teleost. Bystriansky, J. Intermediary metabolism of Arctic char Salvelinus alpinus during short-term salinity exposure. Chew, S. Intestinal osmoregulatory acclimation and nitrogen metabolism in juveniles of the freshwater marble goby exposed to seawater.

B , — Regulation of lactate dehydrogenase in tilapia Oreochromis mossambicus gills during acclimation to salinity challenge. CAS Google Scholar. Chang, E. A Ecol. Article Google Scholar. Tok, C. Gene cloning and mRNA expression of glutamate dehydrogenase in the liver, brain, and intestine of the swamp eel, Monopterus albus Zuiew , exposed to freshwater, terrestrial conditions, environmental ammonia, or salinity stress.

Sundh, H. Biochemical characterization of isolated branchial mitochondria-rich cells of Oreochromis mossambicus acclimated to fresh water or hyperhaline sea water. Walton, M. Aspects of intermediary metabolism in salmonid fish.

B Comp Biochem 73 , 59—79 Phromphetcharat, V. Ammonia partitioning between glutamine and urea: interorgan participation in metabolic acidosis.

Kidney Int. Ammonia is the waste produced by metabolism of nitrogen-containing compounds like proteins and nucleic acids. While aquatic animals can easily excrete ammonia into their watery surroundings, terrestrial animals have evolved special mechanisms to eliminate the toxic ammonia from their systems.

Urea is the major byproduct of ammonia metabolism in vertebrate animals. Uric acid is the major byproduct of ammonia metabolism in birds, terrestrial arthropods, and reptiles.

Skip to content Chapter Osmotic Regulation and Excretion. Learning Objectives By the end of this section, you will be able to: Compare and contrast the way in which aquatic animals and terrestrial animals can eliminate toxic ammonia from their systems Compare the major byproduct of ammonia metabolism in vertebrate animals to that of birds, insects, and reptiles. Excretion of Nitrogenous Waste The theory of evolution proposes that life started in an aquatic environment.

Gout Mammals use uric acid crystals as an antioxidant in their cells. Figure Compare and contrast the formation of urea and uric acid. Answers A C It is believed that the urea cycle evolved to adapt to a changing environment when terrestrial life forms evolved. The urea cycle is the primary mechanism by which mammals convert ammonia to urea. The urea cycle utilizes five intermediate steps, catalyzed by five different enzymes, to convert ammonia to urea.

Birds, reptiles, and insects, on the other hand, convert toxic ammonia to uric acid instead of urea. Conversion of ammonia to uric acid requires more energy and is much more complex than conversion of ammonia to urea. Glossary ammonia compound made of one nitrogen atom and three hydrogen atoms ammonotelic describes an animal that excretes ammonia as the primary waste material antioxidant agent that prevents cell destruction by reactive oxygen species blood urea nitrogen BUN estimate of urea in the blood and an indicator of kidney function urea cycle pathway by which ammonia is converted to urea ureotelic describes animals that secrete urea as the primary nitrogenous waste material uric acid byproduct of ammonia metabolism in birds, insects, and reptiles.