関: choanocyte

WordNet

any of the flagellated cells in sponges having a collar of cytoplasm around the flagellum; they maintain a flow of water through the body (同)collar_cell
seize by the neck or collar
a figurative restraint; "asked for a collar on program trading in the stock market"; "kept a tight leash on his emotions"; "hes always gotten a long leash" (同)leash
a band that fits around the neck and is usually folded over (同)neckband
the stitching that forms the rim of a shoe or boot (同)shoe collar
(zoology) an encircling band or marking around the neck of any animal
a band of leather or rope that is placed around an animals neck as a harness or to identify it
a short ring fastened over a rod or shaft to limit, guide, or secure a machine part
anything worn or placed about the neck; "the thief was forced to wear a heavy wooden collar"; "a collar of flowers was placed about the neck of the winning horse"
take into custody; "the police nabbed the suspected criminals" (同)nail, apprehend, arrest, pick_up, nab, cop
furnish with a collar; "collar the dog"
small room in which a monk or nun lives (同)cubicle
a device that delivers an electric current as the result of a chemical reaction (同)electric cell
a room where a prisoner is kept (同)jail cell, prison cell
(biology) the basic structural and functional unit of all organisms; they may exist as independent units of life (as in monads) or may form colonies or tissues as in higher plants and animals
any small compartment; "the cells of a honeycomb"
a small unit serving as part of or as the nucleus of a larger political movement (同)cadre
variety of kale having smooth leaves

PrepTutorEJDIC

(衣服の)『えり』,カラー / 首飾り;(勲章としての)頚(けい)章,首章 / (犬などの)首輪;(馬・牛などの)首当て / 〈依服〉‘に'カラーをつける;〈犬〉‘に'首輪をつける / 〈人〉‘の'えり首を捕まえる / 《話》〈犯人など〉'を'捕らえる;〈帰りたがっている人〉'を'引き止めて話し込む / 《俗》〈物〉'を'持つ去る,盗む
(刑務所の)『独房』;(修道院の)小さい独居室 / (ミツバチの)みつ房,巣穴 / 小さい部屋 / 『細胞』 / 電池 / 花粉室 / (共産党などの)細胞
コラード(米国部のチリメンキャベツの一種)

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/09/16 15:26:22」(JST)

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Mesohyl

Pinacocyte

Choanocyte

Lophocyte

Porocyte

Oocyte

Archeocyte

Sclerocyte

Spicule

Water flow

Main cell types of Porifera^[1]

Choanocytes (also known as "collar cells") are cells that line the interior of asconoid, syconoid and leuconoid body type sponges that contain a central flagellum, or undulipodia,^[2] surrounded by a collar of microvilli which are connected by a thin membrane. They make up Choanoderm, a type of cell layer found in sponges. The cell has the closest resemblance to the choanoflagellates which are the closest related single celled protists to the animal kingdom (metazoans). The flagellae beat regularly, creating a water flow across the microvilli which can then filter nutrients from the water taken from the collar of the sponge. Food particles are then phagocytosed by the cell. ^[3]

Location

Choanocytes are found dotting the surface of the spongocoel in asconoid sponges and the radial canals in syconoid sponges, but they comprise entirely the chambers in leuconoid sponges.

Function

By cooperatively moving their flagella, choanocytes generate a flow of water through the sponges pores, into the spongocoel, and out through the osculum. This improves both respiratory and digestive functions for the sponge, pulling in oxygen and nutrients and allowing a rapid expulsion of carbon dioxide and other waste products. Although all cells in a sponge are capable of living on their own, choanocytes carry out most of the sponge's ingestion, passing digested materials to the amoebocytes for delivery to other cells.

Choanocytes can also turn into spermatocytes when needed for sexual reproduction, due to the lack of reproductive organs in sponges (amoebocytes become the oocytes).

Evolutionary Significance

Choanocytes bear more than a passing resemblance to Choanoflagellates, and demonstrate key steps in the evolution of animals. Scientist Nicole King helped to establish the distinction.^[4] DNA sequencing indicates that multicellular choanoflagellates and poriferans are sister groups, both descended from the same eukaryotic clade. One can see modern choanoflagellates living in small colonies, illustrating the evolution of sponges by analogy. More complex animals, notably the cnidarians, possess cells whose structures are clearly derived from choanocytes, demonstrating their historical ties to phylum porifera.

References

^ Ruppert, E.E.; Fox, R.S. & Barnes, R.D. (2004). Invertebrate Zoology (7th ed.). Brooks / Cole. p. 82. ISBN 0030259827.
^ A Dictionary of Biology , 2004, accessed 2010-04-06.
^ Anderson, D. (2001) Invertebrate Zoology Oxford University Press
^ Shubin, Neil "Your Inner Fish"

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English Journal

Squamous Neoplasia of the Scrotum: A Series of 29 Cases.

Matoso A1, Ross HM, Chen S, Allbritton J, Epstein JI.Author information 1Departments of *Pathology §Oncology ∥Urology, The Johns Hopkins Hospital, Baltimore ‡Miraca LifeScience Laboratory, Glen Burnie, MD †Department of Pathology, Rhode Island Hospital, Providence, RI.AbstractThe current epidemiology and clinicopathologic features of squamous cell carcinoma (SCC) of the scrotum are largely unknown because of its low incidence. We describe the histopathologic features, immunohistochemistry, and human papillomavirus (HPV) status of 29 patients with scrotal SCC. The mean age at presentation was 55 years (range, 30 to 74 y). White to black ratio was 1.9:1. There was no predominant occupation, with the majority being white-collar professionals. Clinical history of condylomas was present in 5 patients, and 7 patients had a history of multiple skin cancers including melanoma, basal cell carcinoma, and other SCCs. Other comorbidities included human immunodeficiency virus infection (n=2), kidney transplant (n=1), leukemia/lymphoma (n=2), hidradenitis suppurativa (n=1), chronic scrotal infections with abscess (n=1), inflamed epidermal inclusion cyst (n=1), and lichen planus (n=1). One patient had a history of regular tanning bed use. Morphologically, the majority was usual type (n=17), followed by basaloid (n=7) and warty (n=5). Nineteen cases were in situ, and 10 were invasive. Three patients had inguinal lymphadenopathy; in 1, metastasis was confirmed. Suprabasal nuclear staining for Ki67 was considered positive. For p16, a continuous band of nuclear and cytoplasmic staining was considered positive, and a noncontinuous or absence of staining was considered negative. p16 was positive in 10 cases; high-risk HPV was confirmed in 7 cases. Ki67 was positive in 8/17 (47%) usual, 6/7 (85.7%) basaloid, and 3/5 (60%) warty type. p53 was positive in 5/17 (29.4%) usual, 2/7 (28.6%) basaloid, and 1/5 (20%) warty type. All patients were treated with local excision only; 13 had positive margins. Three patients were treated with imiquimod after local excision. The median follow-up was 30 months. Three patients recurred and were treated with re-excision; 1 patient received radiotherapy. Overall, the morphologic, immunohistochemical, and HPV studies show that, similar to SCC of the vulva or penis, the SCC of the scrotum can be divided into 2 major groups. Group 1 (38.5%): positive for p16 and elevated Ki67. This group is associated with HPV infection and displays predominantly a basaloid or warty morphology, although a number of them are of usual type. Group 2 (61.5%): negative for p16. This group has variable Ki67 expression, is consistently negative for HPV, and displays predominantly usual-type morphology. SCC of the scrotum in the United States currently affects primarily white-collar professionals. The majority present with in situ lesions, and the high rate of positive margins at first excision suggests that they are clinically ill-defined lesions. No longer are occupational exposures to carcinogens the major etiology of scrotal SCC. Rather in contemporary times, common risk factors include HPV infection, immunocompromised states, and chronic scrotal inflammatory conditions.
The American journal of surgical pathology.Am J Surg Pathol.2014 Mar 10. [Epub ahead of print]
The current epidemiology and clinicopathologic features of squamous cell carcinoma (SCC) of the scrotum are largely unknown because of its low incidence. We describe the histopathologic features, immunohistochemistry, and human papillomavirus (HPV) status of 29 patients with scrotal SCC. The mean ag
PMID 24618607

Relax and refill: xylem rehydration prior to hydraulic measurements favours embolism repair in stems and generates artificially low PLC values.

Trifilò P1, Raimondo F, Lo Gullo MA, Barbera PM, Salleo S, Nardini A.Author information 1Dipartimento di Scienze Biologiche e Ambientali, Università di Messina, salita F. Stagno D'Alcontres 31, 98166 Messina, Italia.AbstractDiurnal changes in percentage loss of stem hydraulic conductivity (PLC), with recorded values being higher at midday than on the following morning, have been interpreted as evidence for the occurrence of cycles of xylem conduits' embolism and repair. Recent reports have suggested that diurnal PLC changes might arise as a consequence of an experimental artefact i.e. air entry into xylem conduits upon cutting stems, even if under water, while under substantial tension generated by transpiration. Rehydration procedures prior to hydraulic measurements have been recommended to avoid this artefact. In the present study, we show that xylem rehydration prior to hydraulic measurements might favour xylem refilling and embolism repair, thus leading to PLC values erroneously lower than those actually experienced by transpiring plants. When xylem tension relaxation procedures were performed on stems where refilling mechanisms had been previously inhibited by mechanical (girdling) or chemical (orthovanadate) treatment, PLC values measured in stems cut under native tension where the same as those measured after sample rehydration/relaxation. Our data call for renewed attention to procedures of sample collection in the field and transport to the laboratory, and suggest that girdling might be a recommendable treatment prior to sample collection for PLC measurements.
Plant, cell & environment.Plant Cell Environ.2014 Mar 3. doi: 10.1111/pce.12313. [Epub ahead of print]
Diurnal changes in percentage loss of stem hydraulic conductivity (PLC), with recorded values being higher at midday than on the following morning, have been interpreted as evidence for the occurrence of cycles of xylem conduits' embolism and repair. Recent reports have suggested that diurnal PLC ch
PMID 24588546

Biological adhesion of the flatworm Macrostomum lignano relies on a duo-gland system and is mediated by a cell type-specific intermediate filament protein.

Lengerer B, Pjeta R, Wunderer J, Rodrigues M, Arbore R, Schärer L, Berezikov E, Hess M, Pfaller K, Egger B, Obwegeser S, Salvenmoser W, Ladurner P.AbstractBACKGROUND: Free-living flatworms, in both marine and freshwater environments, are able to adhere to and release from a substrate several times within a second. This reversible adhesion relies on adhesive organs comprised of three cell types: an adhesive gland cell, a releasing gland cell, and an anchor cell, which is a modified epidermal cell responsible for structural support. However, nothing is currently known about the molecules that are involved in this adhesion process.
Frontiers in zoology.Front Zool.2014 Feb 12;11(1):12. [Epub ahead of print]
BACKGROUND: Free-living flatworms, in both marine and freshwater environments, are able to adhere to and release from a substrate several times within a second. This reversible adhesion relies on adhesive organs comprised of three cell types: an adhesive gland cell, a releasing gland cell, and an an
PMID 24520881