Biomedical Engineering Reference
In-Depth Information
Fig. 2.2
Diversity of fish AFGPs. (
a
) Type I AFP from winter flounder. (
b
) Antifreeze glyco-
protein (AFGP). (
c
) Spruce budworm AFP. (
d
)
Tenebrio molitor
AFP. (
e
) Type IV AFP. (
f
,
g
)
Nonrepetitive AFPs. (
f
) Type II AFP from sea raven (2AFP). (
g
) Type III AFP from ocean pout.
Reprinted with permission from ref. [
31
]. Copyright (2002) Elsevier
2.1.3
AFP Diversity
For over 50 years since their initial discovery, AFPs and AFGPs have been identified
in the body fluids of many species of polar fish. Four classes of structurally diverse
fish AFPs (cf. Fig.
2.2
), classified as type I [
32
], type II [
33
], type III [
34
], and type
IV [
35
], have now been identified along with a single class of glycosylated protein
denoted AFGP [
36
].
Although AFPs were first discovered in fish, the phenomenon of thermal
hysteresis was initially observed by Ramsay in larvae of the beetle
Tenebrio molitor
[
37
] during his classic investigation of the physiology of the cryptonephridial rectal
complex. AFPs have also been identified in several other terrestrial arthropods
including spiders [
38
], mites [
39
], and centipedes [
40
]. AFPs have been identified,
often based on their thermal hysteresis activity, in over 40 species of insects
(cf. Fig.
2.2
). Among the insects, 65% of the known AFP-producing species are
beetles [
41
]. AFPs have been shown to be also common in plants [
42
], fungi, and
bacteria [
19
].
