Solenocyte

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In biology, solenocytes are elongated, flagellated cells commonly found in lower invertebrates, such as flatworms (phylum Platyhelminthes), chordates (sub-phylum Cephalochordata) and several other animal species. [1] In terms of function, solenocytes play a significant role in the excretory systems of their host organism(s). [2] For example, the lancelets, also referred to as amphioxus (genus Branchiostoma ), utilize solenocytic protonephridia to perform excretion. [3] In addition to excretion, these cells contribute to ion regulation and osmoregulation. [4] With this in mind, solenocytes form subtypes of protonephridium and are often compared to another specialized excretory cell type, i.e., flame cells. [1] Solenocytes have flagella, while flame cells are generally ciliated. [5]

Contents

Cellular structure and configuration

Figure 1. This image illustrates the basic cellular structure of a solenocyte cluster extending off of a side branch of protonephridium (A and B). The solenocyte cell body is circular in nature and resides at the top of each tubule, while the flagella pass through the length of the intracellular tubule lumen. Cluster of Solenocytes.jpg
Figure 1. This image illustrates the basic cellular structure of a solenocyte cluster extending off of a side branch of protonephridium (A and B). The solenocyte cell body is circular in nature and resides at the top of each tubule, while the flagella pass through the length of the intracellular tubule lumen.

Solenocytes are mesoderm-derived and morphologically diverse cells containing a cytoplasmic cap or enclosed cell body with a nucleus residing in its core. [4] A long tubule is attached to the cell body, and within its intracellular lumen lies either one or two long flagella. [6] The continuously moving vibratile flagella extend from a protein structure, referred to as the basal body, found at the base of the flagellar structure. Extending through the length of the tubule, the flagella are able to protrude into the protonephridium lumen rather designedly (see Figure 1). [4]

The tubule wall structure is composed of thin, pillar-like rods perforated by tiny openings. These pore spaces are likely the site of interstitial fluid filtration. [6]

A nephridium contains approximately 500 solenocytes, each of which is roughly 50 microns in length (this measure includes the nucleated cell body and tubule). [7] The excretory organ of Amphioxus (genus Branchiostoma) belcheri contains clusters of solenocytes (the majority of which are situated along the ligamentum denticulatum coelomic surface). These clusters are composed at patterned intervals, generating groups amongst the renal tubules of B. belcheri, which in a way, resemble mesothelial cells surrounding the human body's internal organs. [3] Additional studies indicate a resemblance to vertebrate podocytes, as vascular fluid within the ligamentum denticulatum may travel into the coelom through the narrow network of solenocyte gaps or foot processes. [8]

Function and mechanistic aspects

Figure 2. The transmission electron micrograph (TEM) depicts the 9+2 array of microtubules of two eukaryotic flagella in cross-sections (upper panel). Eukaryotic Flagellum TEM and Diagram.png
Figure 2. The transmission electron micrograph (TEM) depicts the 9+2 array of microtubules of two eukaryotic flagella in cross-sections (upper panel).

In regards to function, flagella play a significant role in the excretory nature of solenocytes. These motile appendages extend from the solenocyte membrane and utilize the support of an axial filament (or axoneme), basal body, as well as numerous microtubules. [9] That said, the stability of the flagellum is crucial to its motility. The basal body, composed of nine triplet microtubules, functions to anchor the flagella in place (acting as a modified centriole). Situated at the center of each flagellum is the highly conserved axoneme, which contains nine doublet microtubules encircling a pair of singlet microtubules (generating a 9+2 pattern). [10] [11] Thousands of walking dynein motors are attached to the axoneme doublets, resulting in the hydrolysis of adenosine triphosphate (ATP), which fuels flagellar motility. [11] More specifically, the dyneins anchor onto one doublet within the outer microtubule ring, and as they "walk" towards an adjacent doublet, the entire flagellar structure is able to bend and beat (see Figure 2). [12] In sum, flagellar motility enables solenocytes to waft excretory materials and coelomic fluid down the intracellular tubule lumen. [8]

In several lower invertebrates, solenocyte clusters project directly into coelomic canals, where they are submerged in coelomic fluid. [13] This fluid contains a variety of materials, including salts, proteins, and corpuscles (e.g., leucocytes, phagocytes, eleocytes, mucocytes, etc.). In that respect, solenocytes play a major role in osmoregulation, ion regulation, and homeostasis through the movement of coelomic fluid. [14]

Branchiostoma nephridia also have tiny blood vessels, and the protonephridia function to absorb nitrogenous waste from coelomic fluid, as well as the blood sinuses via diffusion. [13]

Implications of research

Figure 3. This diagram outlines the fundamental anatomy of the lancelet, also called amphioxus (Branchiostoma). Lancelet Anatomy.png
Figure 3. This diagram outlines the fundamental anatomy of the lancelet, also called amphioxus (Branchiostoma).

In addition to a greater understanding of excretory organs within other invertebrates, further research on solenocyte composition and function can advance current knowledge on renal function, human health, and even certain genetic diseases within the vertebrate world. The cephalochordate amphioxus (see Figure 3) can contribute to this research as a close relative to vertebrates. [8] [15] [16]

Hatschek’s nephridium

Compared to paired series of protonephridia, Hatschek's nephridium is a large unpaired excretory structure found within Branchiostoma virginiae. The nephridium, along with its collection tubule, is located to the left of the notochord and beside the left anterior aorta. [15] Hatschek's nephridium is like a protonephridium with a single, bent branch consisting of numerous solenocytes. The anterior end of this structure sits directly in front of Hatschek's pit, while the posterior end (at the rear of the velum) opens into the endodermal pharynx. Flagellated filtration cells called cyrtopodocytes occupy the length of the collection tubule. These filtration cells closely resemble solenocyte structure and function. [15]

Renal function

Research suggests that coelomic myoepithelial cells in amphioxus (Branchiostoma) may have significance in renal function. [8] Located along the coelom, myoepithelial cells have both thick (18-25 nm in diameter) and thin (5-7 nm in diameter) microfilaments. That said, these microfilaments appear to be more abundant in myoepithelial cells that are in close proximity to solenocytes attached to the ligamentum denticulatum coelomic surface. [8] The beating of solenocyte flagella to propel coelomic fluid throughout excretory tubules leads to the idea that myoepithelial cells near solenocyte clusters can impact renal function by regulating fluid motility within the coelomic cavity. [8]

Human health and genetic diseases

Within the vertebrate lineage, significant genome duplications took place after the divergence of Branchiostoma, thus making it a potentially valuable model for gaining insight into vertebrate biological mechanisms. [16] Branchiostoma has use for investigating human health and genetic disease. Along with signaling pathways, numerous homologs of vertebrate organs share cellular, developmental, and physiological parameters with their vertebrate equivalents. [16] On that premise, solenocyte function within Branchiostoma could provide insight into metabolic diseases, such as renal cell carcinoma (RCC). [17]

Related Research Articles

<span class="mw-page-title-main">Kidney</span> Organ that filters blood and produces urine in humans

In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and right in the retroperitoneal space, and in adult humans are about 12 centimetres in length. They receive blood from the paired renal arteries; blood exits into the paired renal veins. Each kidney is attached to a ureter, a tube that carries excreted urine to the bladder.

<span class="mw-page-title-main">Flagellum</span> Cellular appendage functioning as locomotive or sensory organelle

A flagellum is a hairlike appendage that protrudes from certain plant and animal sperm cells, from fungal spores (zoospores), and from a wide range of microorganisms to provide motility. Many protists with flagella are known as flagellates.

<span class="mw-page-title-main">Cilium</span> Organelle found on eukaryotic cells

The cilium is a membrane-bound organelle found on most types of eukaryotic cell. Cilia are absent in bacteria and archaea. The cilium has the shape of a slender threadlike projection that extends from the surface of the much larger cell body. Eukaryotic flagella found on sperm cells and many protozoans have a similar structure to motile cilia that enables swimming through liquids; they are longer than cilia and have a different undulating motion.

The evolution of flagella is of great interest to biologists because the three known varieties of flagella – each represent a sophisticated cellular structure that requires the interaction of many different systems.

<span class="mw-page-title-main">Cytoskeleton</span> Network of filamentous proteins that forms the internal framework of cells

The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea. In eukaryotes, it extends from the cell nucleus to the cell membrane and is composed of similar proteins in the various organisms. It is composed of three main components: microfilaments, intermediate filaments, and microtubules, and these are all capable of rapid growth or disassembly depending on the cell's requirements.

<span class="mw-page-title-main">Dynein</span> Class of enzymes

Dyneins are a family of cytoskeletal motor proteins that move along microtubules in cells. They convert the chemical energy stored in ATP to mechanical work. Dynein transports various cellular cargos, provides forces and displacements important in mitosis, and drives the beat of eukaryotic cilia and flagella. All of these functions rely on dynein's ability to move towards the minus-end of the microtubules, known as retrograde transport; thus, they are called "minus-end directed motors". In contrast, most kinesin motor proteins move toward the microtubules' plus-end, in what is called anterograde transport.

<span class="mw-page-title-main">Lancelet</span> Order of chordates

The lancelets, also known as amphioxi, consist of some 30 to 35 species of "fish-like" benthic filter feeding chordates in the subphylum Cephalochordata, class Leptocardii, and family Branchiostomatidae.

In biology, a tubule is a general term referring to small tube or similar type of structure. Specifically, tubule can refer to:

<span class="mw-page-title-main">Flame cell</span> Perform excretion and maintain osmotic pressure in Platyhelminthes

A flame cell is a specialized excretory cell found in simple invertebrates, including flatworms (Platyhelminthes), rotifers and nemerteans; these are the simplest animals to have a dedicated excretory system. Flame cells function like a kidney, removing waste materials. Bundles of flame cells are called protonephridia.

<span class="mw-page-title-main">Axoneme</span>

An axoneme, also called an axial filament is the microtubule-based cytoskeletal structure that forms the core of a cilium or flagellum. Cilia and flagella are found on many cells, organisms, and microorganisms, to provide motility. The axoneme serves as the "skeleton" of these organelles, both giving support to the structure and, in some cases, the ability to bend. Though distinctions of function and length may be made between cilia and flagella, the internal structure of the axoneme is common to both.

The nephridium is an invertebrate organ, found in pairs and performing a function similar to the vertebrate kidneys. Nephridia remove metabolic wastes from an animal's body. Nephridia come in two basic categories: metanephridia and protonephridia. All nephridia- and kidney- having animals belong to the clade Nephrozoa.

<span class="mw-page-title-main">Mesonephros</span> Principal excretory organ during early human embryonic life

The mesonephros is one of three excretory organs that develop in vertebrates. It serves as the main excretory organ of aquatic vertebrates and as a temporary kidney in reptiles, birds, and mammals. The mesonephros is included in the Wolffian body after Caspar Friedrich Wolff who described it in 1759.

<span class="mw-page-title-main">Intraflagellar transport</span> Cellular process

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<span class="mw-page-title-main">Sperm motility</span> Process involved in the controlled movement of a sperm cell

Sperm motility describes the ability of sperm to move properly through the female reproductive tract or through water to reach the egg. Sperm motility can also be thought of as the quality, which is a factor in successful conception; sperm that do not "swim" properly will not reach the egg in order to fertilize it. Sperm motility in mammals also facilitates the passage of the sperm through the cumulus oophorus and the zona pellucida, which surround the mammalian oocyte.

Tektins are cytoskeletal proteins found in cilia and flagella as structural components of outer doublet microtubules. They are also present in centrioles and basal bodies. They are polymeric in nature, and form filaments.

Hepatic caecum or hepatic cecum is a name used in describing various physiological structures in some crustaceans, insects and lancelets. "Hepatic" refers to the liver, and the hepatic caecum may perform some functions that are analogous to the functions of the liver in vertebrates.

<span class="mw-page-title-main">Protist locomotion</span> Motion system of a type of eukaryotic organism

Protists are the eukaryotes that cannot be classified as plants, fungi or animals. They are mostly unicellular and microscopic. Many unicellular protists, particularly protozoans, are motile and can generate movement using flagella, cilia or pseudopods. Cells which use flagella for movement are usually referred to as flagellates, cells which use cilia are usually referred to as ciliates, and cells which use pseudopods are usually referred to as amoeba or amoeboids. Other protists are not motile, and consequently have no built-in movement mechanism.

The kidneys are a pair of organs of the excretory system in vertebrates, which maintains the balance of water and electrolytes in the body (osmoregulation), filters the blood, removes metabolic waste products, and in many vertebrates also produces hormones and maintains blood pressure. In healthy vertebrates, the kidneys maintain homeostasis of extracellular fluid in the body. When the blood is being filtered, the kidneys form urine, which consists of water and excess or unnecessary substances, the urine is then excreted from the body through other organs, which in vertebrates, depending on the species, may include the ureter, urinary bladder, cloaca, and urethra.

Amphioxus or lancelets (Branchiostoma) are members of the Chordata phylum of which all members have a notochord at some point while they are alive. B. belcheri have a notochord, dorsal nerve cord, pharynx, buccal cavity, cirri, tail, dorsal fin, nerve cord, segmented muscle, and ocelli. They are distinguishable by a slightly round dorsal fin, eighty slender preanal fin-chambers, narrow caudal fin, and obtuse angles between fins. They obtain food by filter feeding. They were first reported in 1897 near the Amakusa Islands, specifically off Goshonoura Island, south of Amakusa-Kamishima Island. These islands are located on the west coast of Kyushu, the island furthest south of the four main isles of Japan. In addition to the location of the siting, information regarding reproductive period and morphology was also obtained. B. belcheri are gonochoric, reproducing via external fertilization. B. belcheri are an endangered species, threatened by the influx of pollutants of land-based origin into the sea such as cleaning agents, chemical waste, garbage, mining waste, pesticides, petroleum products, and sewage.

References

  1. 1 2 "Solenocytes are the main excretory structures". Vendantu. 2023.
  2. ↑ "Solenocyte | anatomy | Britannica". www.britannica.com. Retrieved 2023-04-11.
  3. 1 2 Nakao, Taisuke (1965-02-01). "The excretory organ of Amphioxus (Branchiostoma) belcheri". Journal of Ultrastructure Research. 12 (1): 1–12. doi:10.1016/S0022-5320(65)80002-8. ISSN   0022-5320. PMID   14289428.
  4. 1 2 3 "What is the function of Solenocytes?". byjus.com. Retrieved 2023-04-12.
  5. ↑ "Flame Cell - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2023-04-11.
  6. 1 2 Wilson, R. A.; Webster, Lesley A. (1974). "PROTONEPHRIDIA". Biological Reviews. 49 (2): 127–160. doi:10.1111/j.1469-185X.1974.tb01572.x. ISSN   1464-7931. PMID   4604982. S2CID   221531583.
  7. ↑ "Protonephridium Or metanephridium?". byjus.com. Retrieved 2023-04-17.
  8. 1 2 3 4 5 6 Tyson, Greta; Bulger, Ruth (1978). "Coelomic Myoepithelial Cells of Amphioxus and Their Possible Significance in Renal Function". Transactions of the American Microscopical Society. 97 (3): 397–402. doi:10.2307/3225994. JSTOR   3225994 – via JSTOR.
  9. ↑ Nørrevang, Arne (1963). "Fine Structure of the Solenocyte Tree in Priapulus caudatus Lamarck". Nature. 198 (4881): 700–701. Bibcode:1963Natur.198..700N. doi:10.1038/198700a0. ISSN   1476-4687.
  10. ↑ Croft, Jacob; Zabeo, Davide; Subramanian, Radhika; Höög, Johanna (2018). "Composition, structure and function of the eukaryotic flagellum distal tip". Essays in Biochemistry. 62 (6): 815–828. doi:10.1042/EBC20180032. PMC   6281473 . PMID   30464008.
  11. 1 2 Chen, Daniel; Heymann, Michael; Fraden, Seth; Nicastro, Daniela; Dogic, Zvonimir (2015). "ATP Consumption of Eukaryotic Flagella Measured at a Single-Cell Level". Biophysical Journal. 109 (12): 2562–2573. arXiv: 1511.01820 . Bibcode:2015BpJ...109.2562C. doi:10.1016/j.bpj.2015.11.003. PMC   4699893 . PMID   26682814.
  12. ↑ "Motor proteins and muscles | Organismal Biology". organismalbio.biosci.gatech.edu. Retrieved 2023-04-17.
  13. 1 2 "Excretory Organs of Branchiostoma (With Diagram) | Chordata | Zoology". Zoology Notes. 2017-07-03. Retrieved 2023-04-18.
  14. ↑ "Coelomic fluid | zoology | Britannica". www.britannica.com. Retrieved 2023-04-18.
  15. 1 2 3 Ruppert, Edward E. (1996-01-01). "Morphology of Hatschek's Nephridium in Larval and Juvenile Stages of Branchiostoma Virginiae (cephalochordata)". Israel Journal of Zoology. 42 (sup1): S161–S182. doi:10.1080/00212210.1996.10688879 (inactive 31 January 2024). ISSN   0021-2210.{{cite journal}}: CS1 maint: DOI inactive as of January 2024 (link)
  16. 1 2 3 Gibson-Brown, Jeremy J.; Osoegawa, Kazutoyo; McPherson, John D.; Waterston, Robert H.; de Jong, Pieter J.; Rokhsar, Daniel S.; Holland, Linda Z. (2003-12-15). "A proposal to sequence the amphioxus genome submitted to the joint genome institute of the US department of energy". Journal of Experimental Zoology. 300B (1): 5–22. doi:10.1002/jez.b.42. ISSN   0022-104X. PMID   14984031.
  17. ↑ Chakraborty, Samik; Balan, Murugabaskar; Sabarwal, Akash; Choueiri, Toni K.; Pal, Soumitro (2021-08-01). "Metabolic reprogramming in renal cancer: Events of a metabolic disease". Biochimica et Biophysica Acta (BBA) - Reviews on Cancer. 1876 (1): 188559. doi:10.1016/j.bbcan.2021.188559. ISSN   0304-419X. PMC   8349779 . PMID   33965513.
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