Nitrogen Research Paper Video
Nitrogen cycle in the soil Nitrogen Research PaperHomer William Smith — was best known for his work as a renal physiologist.
His extensive research on the mammalian kidney greatly enhanced our understanding of the functional properties of the glomeruli, tubules and renal Nitrogen Research Paper bed, and his examination and comprehension of functional alterations in renal disease garnered him a great deal of respect from clinical physicians and physiologists Nitrogej Pitts, Dabbling should be a term used lightly as Smith's early experiments in comparative physiology built the foundation for our current knowledge of nitrogen excretion in fish.
In his seminal paper in the Journal of Biological Chemistry, Smith became the first researcher to report that the gills are the major site of nitrogen excretion in freshwater fish Smith, In vertebrates, amino acids cannot be stored in the tissues without detrimental effects to the http://rmt.edu.pk/nv/custom/due-to-the-transaction-costs-being-lower/essay-about-working-mothers.php of an animal.
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Therefore, ammonia must be either Nitrogen Research Paper or modified to urea or uric acid to avoid adverse effects on normal physiological function and homeostasis. Although the precise pathologies of ammonia toxicity were not elucidated until over 50 years later reviewed by Ip et al. In contrast, the limited literature available on Reserach at the time indicated that teleosts excreted only small amounts of nitrogenous compounds in their urine Denis, ; Grollman, Smith was intrigued that the main urinary constituent in these studies was reportedly creatine and all other nitrogenous products were unusually low.
Therefore, Smith hypothesized that the most probable route for the loss of nitrogenous waste i. To test his hypothesis, Smith pioneered a simple yet innovative experimental setup that partitioned the anterior end of the fish from the posterior end.
Common carp Cyprinus carpio and goldfish Carassius auratus were individually placed in a box divided into two chambers by two superimposed layers of rubber dam. Sufficient water was put into the chamber to immerse the fish and both chambers were aerated to ensure oxygen levels remained normoxic. The collection of urine was accomplished by the implantation of a Nitrogen Research Paper retention catheter sewn into the urinary papilla and the catheter drained into a light rubber bag: this technique allowed a continuous collection of urine with minimal disturbance to the Nitrogen Research Paper. Following a chemical analysis of the collected samples, Smith reported that the amount of ammonia excreted from the gills, as measured by the accumulation in the anterior chamber, was approximately 6—10 times higher than the urinary output during the same time interval.
Collectively, these findings read article the first not only to unequivocally identify the gills as the primary site of nitrogen excretion in fish but also to demonstrate the differential patterns of nitrogenous waste handling between aquatic and terrestrial animals.
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In the decades following the publication of Smith's paper in Papee Journal of Biological Chemistry, other studies confirmed Smith's basic conclusions on nitrogen excretion in teleosts Fromm, ; Goldstein and Forster, ; Wood, Both these approaches were useful for generating a large amount of excellent data during the s and s. The results from these studies revealed that ammonia excretion was variable and could be influenced by the fasting versus fed state of the animal, activity levels, and numerous environmental conditions Resfarch.
Moreover, researchers began to discover notable exceptions to the observation that teleosts excrete the majority of their waste in the form of ammonia. The Lake Magadi tilapia Nitrogen Research Paper alcalicus grahamGulf toadfish Opsanus betaSinghi catfish Heteropneustes fossilis and slender lungfish Protopterus dolloi have all adopted unconventional patterns of urea excretion in Nitrogen Research Paper to various environmental constraints that typically limit ammonia excretion reviewed by Ip and Chew, ; McDonald et al.
References
Less than two decades ago, the simultaneous discoveries and subsequent characterization of Rhesus Rh glycoproteins and facilitated Nitrogen Research Paper transporters UT in mammals led to a renaissance in the study of ammonia and urea excretion, respectively, in fish. A detailed discussion on these ammonia and urea transport paradigms in fish is beyond the scope of this article; however, the updated piscine model on ammonia excretion has been thoroughly and elegantly summarized by Wright and Wood, source a role for Rh glycoproteins as NH3 conduits in freshwater fish Wright and Wood, ; Wright and Wood, McDonald and colleagues have compiled comprehensive reviews on the mechanisms of urea transport in fish gills read article summarized the compelling data that demonstrate that UTs play a crucial role in the removal of urea in both ureotelic urea-excreting and ammoniotelic ammonia-excreting teleosts see McDonald et al.
From this literature, it is clear there has been a shift from quantitative studies on nitrogen excretion Nifrogen in-depth characterization and analyses of the regulation of transport mechanisms controlling both branchial ammonia and urea excretion in fish. In the many biographical memoirs written since Smith's death incolleagues Nitrogen Research Paper fellow researchers have Nutrogen Smith's praise for his contribution to mammalian renal physiology see Berliner, ; Pitts, ; Nitrogen Research Paper, it is also clear that comparative physiologists likewise owe a great debt of gratitude toward Smith's scientific curiosity and genius.]
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