無脊椎動物的Dscam分子被認為參與在“專一性免疫印記”，使動物體獲得短期的專一性免疫反應，此些Dscam分子的胞外區域會經由選擇性剪接具有多變性，這些多變性在神經發育及專一性免疫反應的過程中都被推測具有功能性。然而除了胞外區，蝦類Dscam的胞質尾亦可經由選擇性剪接產生多種表現型，而胞質尾的多變性被推測與驅動下游訊號分子產生不同訊息傳遞的能力有相關。此篇論文分析在蝦類Dscam在蝦類病原體哈威弧菌及白點症病毒感染後之基因調控現象，以推測其於蝦類免疫所扮演之角色。結果顯示在各種形式的蝦類Dscam以及不同的胞質尾表現型皆會被蝦類病原體刺激使表現量上升。利用親源關係分析發現，針對弧菌所誘導出的蝦類Dscam異構型具有高度的相似度，可與正常蝦體所表現之Dcam區分。利用在生物體外進行細菌結合親合性分析法偵測不同菌種與Dscam異構型重組蛋白之間的關係。結果顯示經由哈威弧菌誘導之Dscam異構型與哈威弧菌具有結合親合性。根據以上結果推測蝦類Dscam應有參與蝦類免疫作用，並且專一性之蝦類Dscam異構型也具有辨認哈威弧菌之能力。

In arthropods, the Down syndrome cell adhesion molecule (Dscam) is believed to be involved in “specific immune priming”. The extracellular region of arthropod Dscam can generate a great number of isoforms via mutually exclusive alternative splicing. This variability has been shown to function as a neural wiring adaptor in neural wiring and an antigen-specific receptor in arthropod specific immune responses. In shrimp Dscam, in addition to the extracellular region, cytoplasmic tail variants arise through the alternative splicing of 8 elements. These variants are potentially able to trigger different subsequent signal transductions. This study is the first to investigate the responses of shrimp Dscam during shrimp pathogenic infection by Vibrio harveyi and white spot syndrome virus (WSSV). Expression of shrimp Dscam and its variable cytoplasmic tail variants was stimulated by the injections of V. harveyi and WSSV. The Vibrio-induced shrimp Dscam isoforms were subsequently collected and subjected to a grouping analysis, which showed that half of the major Vibrio-induced shrimp Dscam isoforms were grouped into one clade that was clearly separated from the Dscam isoforms from the uninfected shrimp. An in vitro bacterial binding assay examined the interaction between different bacteria and rLvDscam isoforms. The data showed that the major Vibrio-induced Dscam isoforms have the binding affinity with V. harveyi. Based on these results, we believed that shrimp Dscam is involved in shrimp immunity, and the specific shrimp Dscam isoforms also have the ability to recognize V. harveyi.

1. Adema CM, Hertel LA, Miller RD, Loker ES (1997) A family of fibrinogen-related proteins that precipitates parasite-derived molecules is produced by an invertebrate after infection. Proc Natl Acad Sci U S A. 5;94(16):8691-6.

2. Bachere E, Fuchs R, Söderhäll K (2000) Special issue on shrimp response to pathogens. Aquaculture 191:1–270.

3. Boehm T (2007) Two in one: dual function of an invertebrate antigen receptor. Nat Immunol. 8:1031-1033.

4. Brites D, McTaggart S, Morris K, Anderson J, Thomas K, Colson I, Fabbro T, Little TJ, Ebert D, Du Pasquier L (2008) The Dscam homologue of the crustacean Daphnia is diversified by alternative splicing like in insects. Mol Biol Evol. 25:1429-1439.

5. Chou PH, Chang HS, Chen IT, Lin HY, Chen YM, Yang HL, Wang KC (2009) The putative invertebrate adaptive immune protein Litopenaeus vannamei Dscam (LvDscam) is the first reported Dscam to lack a transmembrane domain and cytoplasmic tail. Dev Comp Immunol. 33:1258-1267.

6. Chou PH, Chang HS, Chen IT, Lee CW, Hung HY, Han-Ching Wang KC (2011) Penaeus monodon Dscam (PmDscam) has a highly diverse cytoplasmic tail and is the first membrane-bound shrimp Dscam to be reported. Fish Shellfish Immunol. 30(4-5):1109-23.

7. Dong Y, Taylor HE, Dimopoulos G (2006) AgDscam, a hypervariable immunoglobulin domain-containing receptor of the Anopheles gambiae innate immune system. PLoS Biol. 4:e229.

8. Early P, Rogers J, Davis M, Calame K, Bond M, Wall R, Hood L (1980) Two mRNAs can be produced from a single immunoglobulin mu gene by alternative RNA processing pathways. Cell. 20(2):313-9.

9. Flegel TW, Lightner DV, Lo CF, Owens L (2008) Shrimp disease control: past, present and future. In: Bondad-Reantaso MG, Mohan CV, Crumlish M, Subasinghe RP (eds) Diseases in Asian aquaculture VI. Fish Health Section, Asian Fisheries Society, Manila, Philippines, pp 355–378.

10. Hanington PC, Forys MA, Dragoo JW, Zhang SM, Adema CM, Loker ES (2010) Role for a somatically diversified lectin in resistance of an invertebrate to parasite infection. Proc Natl Acad Sci U S A. 107(49):21087-92.

11. Hauton C, Smith VJ (2007) Adaptive immunity in invertebrates: a straw house without a mechanistic foundation. Bioessays. 29(11):1138-46.

12. Kurtz J, Armitage SA (2006) Alternative adaptive immunity in invertebrates. Trends Immunol 27:493–6.

13. Labreuche Y, O'Leary NA, de la Vega E, Veloso A, Gross PS, Chapman RW, Browdy CL, Warr GW (2009) Lack of evidence for Litopenaeus vannamei Toll receptor (lToll) involvement in activation of sequence-indepdent antiviral immunity in shrimp. Dev Comp Immunol. 33(7):806-10.

14. Modrek B, Resch A, Grasso C, Lee C (2001) Genome-wide detection of alternative splicing in expressed sequences of human genes. Nucleic Acids Res. 29(13):2850-9.

15. Nehme NT, Quintin J, Cho JH, Lee J, Lafarge MC, Kocks C, Ferrandon D (2011) Relative roles of the cellular and humoral responses in the Drosophila host defense against three gram-positive bacterial infections. PLoS One. 6(3):e14743.

16. Pope EC, Powell A, Roberts EC, Shields RJ, Wardle R, Rowley AF (2011) Enhanced cellular immunity in shrimp (Litopenaeus vannamei) after ‘vaccination’. PLoS One. 6(6):e20960.

17. Roth O, Sadd BM, Schmid-Hempel P, Kurtz J (2009) Strain-specific priming of resistance in the red flour beetle, Tribolium castaneum. Proc Biol Sci. 276(1654):145-51.

18. Rowley AF, Powell A. (2007) Invertebrate immune systems specific, quasi-specific, or nonspecific? J Immunol 179:7209–14.

19. Schmucker D, Clemens JC, Shu H, Worby CA, Xiao J, Muda M, Dixon JE, Zipursky SL (2000) Drosophila Dscam is an axon guidance receptor exhibiting extraordinary molecular diversity. Cell. 101:671-684.

20. Shi L, Yu HH, Yang JS, Lee T (2007) Specific Drosophila Dscam juxtamembrane variants control dendritic elaboration and axonal aborization. J Neurosci. 27(25):6723-8.

21. Söderhäll K (1999) Invertebrate immunity. Dev Comp Immunol 23:263–442.

22. Sritunyalucksana K, Söderhäll K (2000) The proPO and clotting system in crustaceans. Aquaculture 191:53–69.

23. Tanticharoen M, Flegel TW, Meerod W, Grudloyma U, Pisamai N (2008) Aquacultural biotechnology in Thailand: the case of the shrimp industry. Int. J. Biotechnology, Vol. 10, No. 6

24. Takagaki Y, Seipelt RL, Peterson ML, Manley JL (1996) The polyadenylation factor CstF-64 regulates alternative processing of IgM heavy chain pre-mRNA during B cell differentiation. Cell. 87(5):941-52.

25. Terwilliger DP, Buckley KM, Brockton V, Ritter NJ, Smith LC (2007) Distinctive expression patterns of 185/333 genes in the purple sea urchin, Strongylocentrotus purpuratus: an unexpectedly diverse family of transcripts in response to LPS, beta-1,3-glucan, and dsRNA. BMC Mol Biol 8:16.

26. Wang KC, Kondo H, Hirono I, Aoki T (2010) The Marsupenaeus japonicus voltage-dependent anion channel (MjVDAC) protein is involved in white spot syndrome virus (WSSV) pathogenesis. Fish Shellfish Immunol. 29(1):94-103.

27. Watson FL, Püttmann-Holgado R, Thomas F, Lamar DL, Hughes M, Kondo M, Rebel VI, Schmucker D (2005) Extensive diversity of Ig-superfamily proteins in the immune system of insects. Science. 309:1874-1878.

28. Watthanasurorot A, Jiravanichpaisal P, Liu H, Söderhäll I, Söderhäll K (2011) Bacteria-Induced Dscam Isoforms of the Crustacean, Pacifastacus leniusculus. PLoS Pathog. 7(6):e1002062.

29. Wojtowicz WM, Flanagan JJ, Millard SS, Zipursky SL, Clemens JC (2004) Alternative splicing of Drosophila Dscam generates axon guidance receptors that exhibit isoform-specific homophilic binding. Cell. 3;118(5):619-33.

30. Yamakawa K, Huot YK, Haendelt MA, Hubert R, Chen XN, Lyons GE, Korenberg JR (1998) DSCAM: a novel member of the immunoglobulin superfamily maps in a Down syndrome region and is involved in the development of the nervous system. Hum Mol Genet. 7(2):227-37.

31. Yu HH, Yang JS, Wang J, Huang Y, Lee T. (2009) Endodomain diversity in the Drosophila Dscam and its roles in neuronal morphogenesis. J Neurosci. 29(6):1904-14.

32. Zhang S-M, Adema CM, Kepler TB, Loker ES (2004) Diversification of Ig superfamily genes in an invertebrate. Science 305(5681):251–4.