Inalgal anatomy, apit connection is a hole in theseptum between two algal cells, and is found only in multicellularred algae[1] − specifically in the subphylum Eurhodophytina, except haploidBangiales.[2] They are often stoppered with proteinaceous "pit plugs". By contrast, manyfungi (onlyascomycetes andbasidiomycetes, as most other groups lack septa) containseptal pores − an unrelated phenomenon.[3]
A sieve-like membrane may cover the pit in living algae,[4] but in the majority of algae a plug forms, they likely limit the transfer of metabolites between neighbouring cells.[2][5]
Primary pit connections are formed between cells in the same filament, derived from the same parent cell by its division.[4] Such connections are always single, and usually circular;[4] 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.[2] 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.[4] Secondary connections, by contrast, occur between unrelated cells, and serve a role in transferring cell contents and nutrients.[2] They may even form between cells of different species, as in the parasiteHolmsella.[6]
^Clinton J. Dawes; Scott, Flora M.; Bowler, E. (1961), "A Light- and Electron-Microscopic Survey of Algal Cell Walls. I. Phaeophyta and Rhodophyta",American Journal of Botany,48 (10):925–934,doi:10.2307/2439535,JSTOR2439535.
^Ellis, T.T.; Reynolds, D.R.; Alexopoulos, C.J. (1973), "Hulle Cell Development in Emericella nidulans",Mycologia,65 (5):1028–1035,doi:10.2307/3758285,JSTOR3758285.
^abcdFritsch, F. E. (1945),The structure and reproduction of the algae, Cambridge: Cambridge Univ. Press,ISBN0521050421,OCLC223742770{{citation}}:ISBN / Date incompatibility (help)
^Wetherbee, R.; Quirk, H. M. (1982). "The fine structure of secondary pit connection formation between the red algal alloparasiteHolmsella australis and its red algal hostGracilaria furcellata".Protoplasma.110 (3):166–176.doi:10.1007/BF01283319.S2CID21177509.
Transverse SEM images of pit connections in the corallineSynarthrophyton can be seen in Figs. 54 & 60 inKeats, D. W; Chamberlain, Y. M (1997), "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",European Journal of Phycology,32 (1):55–79,doi:10.1080/09541449710001719375
(Lower quality) transverse SEM images of pit connections in the corallinePhymatolithon are available on page 138 atJohnson, C.; Mann, K. (1986). "The crustose coralline alga,Phymatolithon Foslie, inhibits the overgrowth of seaweeds without relying on herbivores".Journal of Experimental Marine Biology and Ecology.96 (2):127–146.doi:10.1016/0022-0981(86)90238-8..
