Down syndrome cell adhesion molecule (Dscam) seems
likely to play a key role in the “alternative adaptive immunity”
as reported in invertebrates. In some invertebrate animals,
such as mosquito and Drosophila, the innate immune responses are supplemented by a novel immunity that exhibits
specificity and memory. The mechanism is not well understood, but a pathogen-specific receptor capable of high diversity is presumably required. Different means evolved from
different invertebrates to achieve this goal. In arthropods, the
diversity is seen in Dscam. The studies of Watson et al. [62]
have identified a homologue of Dscam in fruit flies (Drosophila) that is expressed in key phagocytic cell types in this
insect’s immune system. These workers have estimated that
18,000 isoforms of Dscam could be formed by sequence variation in the three immunoglobulin-like domains of this molecule, and these variations probably allowed Dscam to show
differential binding to foreign agents in an analogous way as 6 Journal of Marine Science and Technology, Vol. 22, No. 1 (2014)
vertebrate antibody binds different antigens. In a related invertebrate (the mosquito) further experimentation has revealed
the production of different Dscam-like molecules with varying
pathogen interaction specificities after challenge with different
pathogens [26] which is analogous to the clonal selection
mechanism of vertebrate immunity. Dscam consists of a cytoplasmic tail that is involved in signal transduction and a
hypervariable extracellular region that might use a pathogen
recognition mechanism similar to that used by the vertebrate
antibodies. Dscam was isolated from shrimps such as L.
vannamei and P. monodon and occurred in both membrane-bound and tail-less forms [18, 19].
Down syndrome cell adhesion molecule (Dscam) seems likely to play a key role in the “alternative adaptive immunity” as reported in invertebrates. In some invertebrate animals, such as mosquito and Drosophila, the innate immune responses are supplemented by a novel immunity that exhibits specificity and memory. The mechanism is not well understood, but a pathogen-specific receptor capable of high diversity is presumably required. Different means evolved from different invertebrates to achieve this goal. In arthropods, the diversity is seen in Dscam. The studies of Watson et al. [62] have identified a homologue of Dscam in fruit flies (Drosophila) that is expressed in key phagocytic cell types in this insect’s immune system. These workers have estimated that 18,000 isoforms of Dscam could be formed by sequence variation in the three immunoglobulin-like domains of this molecule, and these variations probably allowed Dscam to show differential binding to foreign agents in an analogous way as 6 Journal of Marine Science and Technology, Vol. 22, No. 1 (2014)vertebrate antibody binds different antigens. In a related invertebrate (the mosquito) further experimentation has revealed the production of different Dscam-like molecules with varying pathogen interaction specificities after challenge with different pathogens [26] which is analogous to the clonal selection mechanism of vertebrate immunity. Dscam consists of a cytoplasmic tail that is involved in signal transduction and a ภูมิภาค extracellular hypervariable ที่อาจใช้เป็นการศึกษา กลไกการรับรู้ที่ใช้ในสัตว์มีกระดูกสันหลัง แอนตี้กัน Dscam ที่แยกได้จากกุ้งเช่น L. กุลา และ P. monodon และเกิดขึ้นในฟอร์มผูก กับเมมเบรน และหาง [18, 19]
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