Pit connection

In algal anatomy, a '''pit connection''' is a hole in the septum between two algal cells, and is found only in multicellular red algae<ref name=Clinton1961 /> − specifically in the subphylum Eurhodophytina, except haploid Bangiales.<ref name=lee2008>{{citation|author=lee, R.E.|title=Phycology, 4th edition|year=2008|isbn=978-0-521-63883-8|publisher=Cambridge University Press|url-access=registration|url=https://archive.org/details/phycology00robe}}</ref> They are often stoppered with proteinaceous "pit plugs". By contrast, many fungi (only ascomycetes and basidiomycetes, as most other groups lack septa) contain '''septal pores''' − an unrelated phenomenon.<ref name=EllisEtAl1973 />

==Characteristics== A sieve-like membrane may cover the pit in living algae,<ref name=Fritsch1945/> but in the majority of algae a plug forms, they likely limit the transfer of metabolites between neighbouring cells.<ref name=lee2008 /><ref name=Turner1978 />

==Formation== Primary pit connections are formed between cells in the same filament, derived from the same parent cell by its division.<ref name=Fritsch1945/> Such connections are always single, and usually circular;<ref name=Fritsch1945/> this is a result of their method of formation. The septum is formed as the walls of a filament grow inwards, dividing the cell; this results in a hole in the middle of the tube where the walls don't quite merge.<ref name=lee2008/> Thus pit connections are visible in the youngest of septa, widening as the septum thickens, until in some cases they may ultimately occupy the entire septum.<ref name=Fritsch1945/> Secondary connections, by contrast, occur between unrelated cells, and serve a role in transferring cell contents and nutrients.<ref name=lee2008 /> They may even form between cells of different species, as in the parasite ''Holmsella''.<ref name=Wetherbee1981 />

==References== <references>

<ref name=Clinton1961>{{Citation | author = Clinton J. Dawes | author2 = Scott, Flora M. |author3=Bowler, E. | year = 1961 | title = A Light- and Electron-Microscopic Survey of Algal Cell Walls. I. Phaeophyta and Rhodophyta | journal = American Journal of Botany | volume = 48 | issue = 10 | pages = 925–934 | doi = 10.2307/2439535 | postscript = . | jstor = 2439535 }}</ref> <ref name=EllisEtAl1973>{{Citation | doi = 10.2307/3758285 | author = Ellis, T.T. |author2=Reynolds, D.R. |author3=Alexopoulos, C.J. | journal = Mycologia | volume = 65 | issue = 5 | pages = 1028–1035 | year = 1973 | title = Hulle Cell Development in'' Emericella nidulans'' | jstor = 3758285 | postscript = . }}</ref> <ref name=Turner1978>{{citation | author = Turner, C. H. C. |author2=Evans, L. V. | year = 1978 | title = Translocation of photoassimilated <sup>14</sup>C in the red alga Polysiphonia lanosa | journal = European Journal of Phycology | volume = 13 | issue = 1 | pages = 51–55 | doi = 10.1080/00071617800650061 | url = http://www.informaworld.com/index/771027465.pdf }}</ref>    <ref name=Wetherbee1981>{{Cite journal | last1 = Wetherbee | first1 = R. | last2 = Quirk | first2 = H. M. | doi = 10.1007/BF01283319 | title = The fine structure of secondary pit connection formation between the red algal alloparasite ''Holmsella australis'' and its red algal host ''Gracilaria furcellata'' | journal = Protoplasma | volume = 110 | issue = 3 | pages = 166–176 | year = 1982 | s2cid = 21177509 }}</ref> <ref name=Fritsch1945>{{Fritsch 1945}}</ref>

</references>

== External links == * Transverse SEM images of pit connections in the coralline ''Synarthrophyton'' can be seen in Figs. 54 & 60 in {{Citation | doi = 10.1080/09541449710001719375 | author1 = Keats, D. W | author2 = Chamberlain, Y. M | title = The non-geniculate coralline algae Synarthrophyton eckloniae (Foslie) comb. nov. and S. magellanicum (Foslie) comb. nov. (Rhodophyta) in South Africa including comparison with relevant types | journal = European Journal of Phycology | volume = 32 | issue = 1 | pages = 55–79 | year = 1997 | doi-access = free }} * (Lower quality) transverse SEM images of pit connections in the coralline ''Phymatolithon'' are available on page 138 at {{Cite journal | last1 = Johnson | first1 = C. | last2 = Mann | first2 = K. | title = The crustose coralline alga, ''Phymatolithon'' Foslie, inhibits the overgrowth of seaweeds without relying on herbivores | journal = Journal of Experimental Marine Biology and Ecology | volume = 96 | issue = 2 | pages = 127–146 | year = 1986 | doi = 10.1016/0022-0981(86)90238-8 }}.

Category:Red algae