Alae (nematode anatomy)
Thealaeis a protruding ridge that forms longitudinally on manynematodes. In theCaenorhabditis elegansnematodethey are present in the L1,dauer(an alternative long living larvae stage where the nematode is dormant) and adult stages. The alae are most pronounced during thedauer larval stageand not present in the L2, and L3C. elegansstages.[clarification needed]
The term ‘alae’ is the plural of ala (wing), describing either one of the pair of ridges that forms on anematodeor an individual crease found on an individual ridge. The term ‘ala’ is rarely used in describing the alae and scientific journals use the term ‘alae’ both singularly and in the plural.
Structure[edit]
The alae is formed by thehypodermal seam cellswhere a fibrous ribbon of azona pellucida(ZP) domainproteinis produced. InC. elegansmany of these proteins are termed CUT-1.[1]The CUT refers tocuticulinswhich are the variousproteinsthat are not solubilised by both reducing agents anddetergents[2]made insoluble by the nature of their crosslinks.[3][4]
Described as a matrix that appears to be holding the two sides of thecollagenouscuticletogether for strengthening[5]it should also be interpreted as a matrix separating the cuticle thereby exposing itself to the external environment.[6]The alae is formed during anoxidative processwhereperoxidaseacts onproteinboundtyrosineresidues. The alae is a crease, that by the cross linking process causes radial shrinking of the seam cell secretedproteins.
Function[edit]
The function of the alae is not yet clear. It is generally given a function related tocuticlestrength,nematodemovement orfatstorage. But the predominant structure of theC. elegansalae contain theZPdomain proteins (CUT-1, CUT-3, CUT-5). The ZP domain had been termed ‘the sequence in search of a function’ and has been given the functional role of matrix assembly and also putatively, functions inpheromoneand olfactorysignal transduction.[7][8]Despite the structural nature of theZPdomain, it is not the ideal protein for strength alone. WhereverZPdomains are found, they are found in definite or putative association withsignal transductionaccompanied by interaction with an external or hostile environment.
Function based on genetic data of theH. Contortusdauer nematode[edit]
In the parasitic nematodeHaemonchus contortusaZPdomain protein of adauerstage nematode has been genetically associated to a target molecule found in the environment that this nematode could be using for exiting thedauerstage. This was statistically related with a high degree of significance indicating that the alae may specifically function as a receptor site.
In the case ofH. contortusthedauernematodecan remain in thegastric epitheliumfor months and until the right signals indicating conditions outside the host are favorable for egg survival, it will then trigger resumption of development. During thedauer stagethe mouth and anal openings are sealed and neural receptors around the head retracted. The alae is more pronounced than at any other stage and remains exposed to the external environment. Triggers for exiting thedauerstate may be determined by the concentration of target molecules around thenematode.In order to measure concentrations accurately, a very large receptor area is necessary, hence a structure such as the alae may be required.
Postulated function[edit]
The alae appears to be aneuralreceptorresponsive to just a handful of molecules particular to eachspeciesofnematode.Up to half a dozen types of receptors may be present at any one time on the alae and each type would be very numerous. The target molecules in the environment that stimulate each type of receptor may then be measured for their concentration and a threshold reached before an action is instigated. These actions may instigate entry into thedauer state (L1 alae),exiting of thedauerstate (pheromoneand or presence of an indicator for food availability), forsexual reproductionwhere the area around thevulvaandgonadsof the female and male use this family of receptors (RAM-5) where thenematodeis likely to identify thatreproductive organsare in contact.[9]And quite probably there are some other functions that we have not yet been found.[according to whom?]
References[edit]
- ^Ristoratore, F; Cermola, M; Nola, M; Bazzicalupo, P; Favre, R (July 1994). "Ultrastructural immuno-localization of CUT-1 and CUT-2 antigenic sites in the cuticles of the nematodeCaenorhabditis elegans".Journal of Submicroscopic Cytology and Pathology.26(3): 437–43.PMID8087805.
- ^Fujimoto, Daisaburo; Kanaya, Shigenori (July 1973). "Cuticlin: a noncollagen structural protein fromAscaris cuticle".Archives of Biochemistry and Biophysics.157(1): 1–6.doi:10.1016/0003-9861(73)90382-2.PMID4352055.
- ^Lewis, E.; Sebastiano, M.; Nola, M.; Zei, F.; Lassandro, F.; Ristoratore, F.; Cermola, M.; Favre, R.; Bazzicalupo, P. (1 October 2014)."Cuticlin genes of nematodes".Parasite.1(1S): S57–S58.doi:10.1051/parasite/199401s1057.
- ^Lewis, E; Hunter, SJ; Tetley, L; Nunes, CP; Bazzicalupo, P; Devaney, E (25 June 1999). "cut-1-like genes are present in the filarial nematodes,Brugia pahangiandBrugia malayi,and, as in other nematodes, code for components of the cuticle ".Molecular and Biochemical Parasitology.101(1–2): 173–83.doi:10.1016/S0166-6851(99)00070-5.PMID10413052.
- ^De Giorgi, C.; De Luca, F.; Di Vito, M.; Lamberti, F. (20 February 1997). "Modulation of expression at the level of splicing of cut-1 RNA in the infective second-stage juvenile of the plant parasitic nematodeMeloidogyne artiellia".Molecular and General Genetics.253(5): 589–598.doi:10.1007/s004380050361.PMID9065692.S2CID11819745.
- ^Vermont, R.C., (2003) Characterisation of cDNA fromHaemonchus contortus(Barber's poleworm) encoding a Cuticulin. Dissertation, Charles Sturt University NSW. This information is not publicly available and is held at CSU School of Agriculture. Further information may be sourced by emailing the author
- ^Matsushita, F; Miyawaki, A; Mikoshiba, K (16 February 2000). "Vomeroglandin/CRP-Ductin is strongly expressed in the glands associated with the mouse vomeronasal organ: identification and characterization of mouse vomeroglandin".Biochemical and Biophysical Research Communications.268(2): 275–81.doi:10.1006/bbrc.2000.2104.PMID10679193.
- ^Sutton, KA; Jungnickel, MK; Florman, HM (June 2002). "If music be the food of love…".Nature Cell Biology.4(6): E154-5.doi:10.1038/ncb0602-e154.PMID12042831.S2CID42749251.
- ^Yu, RY; Nguyen, CQ; Hall, DH; Chow, KL (17 July 2000)."Expression of ram-5 in the structural cell is required for sensory ray morphogenesis inCaenorhabditis elegansmale tail ".The EMBO Journal.19(14): 3542–55.doi:10.1093/emboj/19.14.3542.PMC313976.PMID10899109.