|
Adaptive Immunity In Jawless Fish
Agnatha, Jawless vertebrates, which today consist entirely of lampreys and hagfish, have an adaptive immune system similar to that found in Gnathostomata, jawed vertebrates. The cells of the agnathan AIS have roles roughly equivalent to those of B cell, B-cells and T cell, T-cells, with three lymphocyte lineages identified so far: *VLRA (most similar to T cell, α/β T cells, in its role and pathway of differentiation) *VLRB (most similar to B cells) *VLRC (most similar to gamma/delta T cells, γ/δ T cells) VLRA and VLRB were identified in 2009, while VLRC was discovered in 2013. Instead of immunoglobulins, they use variable lymphocyte receptors. Antigen receptors Jawless vertebrates do not have Immunoglobulin superfamily, immunoglobulins (Igs), the key proteins to B-cells and T-cells. However, they do possess a system of leucine-rich repeat (LRR) proteins that make up variable lymphocyte receptors (VLRs). This system can produce roughly the same number of potential receptors t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agnatha
Agnatha (, Ancient Greek 'without jaws') is an infraphylum of jawless fish in the phylum Chordata, subphylum Vertebrata, consisting of both present (cyclostomes) and extinct (conodonts and ostracoderms) species. Among recent animals, cyclostomes are sister to all vertebrates with jaws, known as gnathostomes. Recent molecular data, both from rRNA and from mtDNA as well as embryological data, strongly supports the hypothesis that living agnathans, the cyclostomes, are monophyletic. The oldest fossil agnathans appeared in the Cambrian, and two groups still survive today: the lampreys and the hagfish, comprising about 120 species in total. Hagfish are considered members of the subphylum Vertebrata, because they secondarily lost vertebrae; before this event was inferred from molecular and developmental data, the group Craniata was created by Linnaeus (and is still sometimes used as a strictly morphological descriptor) to reference hagfish plus vertebrates. While a few s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
