Acetylcholinesterase (AChE, EC 3.1.1.7) plays a vital role in neurotransmission in both vertebrates and invertebrates. AChE is a key enzyme in the insect nervous system, in which the cholinergic system is essential. In addition to its classical synaptic functions, AChE is recently known to play other non-neuronal roles. In vertebrates, only one AChE has been shown to be involved in both neuronal and non-neuronal functions, whereas two different AChEs have been identified from various insect species, and seem to play respective neuronal and non-neuronal functions. In honey bee, for instance, membrane-anchored AChE2 is reported to be responsible for classical synaptic functions, while soluble AChE1 plays non-neuronal functions. In contrast to most insect species expressing two AChEs, Cyclorrhaphan flies are known to possess only a single ace locus. In Cyclorrhapha possessing only one AChE, multiple forms (molecular variation) of Drosophila melanogaster AChE (DmAChE) were recently suggested to be generated via alternative splicing. Among various molecular forms, membrane-anchored dimer has high enzyme activity, whereas soluble monomer is abundantly expressed without catalytic activity. Interestingly, expression of the soluble DmAChE was induced by chemical stress. Based on the results, it can be hypothesized that the generation of multiple isoforms of AChE2, particularly the soluble forms, may have provided alternative protein copies for AChE1, replaced the functions of AChE1 and eventually allowed the loss of AChE1 in Cyclorrhaphan flies.

[ (1~to3 ) ], (1~to4 )-β -D-glucans(β-glucans ) are a major component of the cell walls of grasses as a component of the cereal endosperm and aleurone cell walls. Although β-glucans exist in all cereals, their concentration is highest in oats and barley. Genetic and environmental differences are found in total β-glucan content. Both oats and barley β-glucans have cholesterol-lowering effects. This suggests possible use as food additives. Structural characterization of β-glucan is important because structure can influence physical and physiological properties. In this review, β-glucans of barley and oats are discussed in details including structure, chemical and physical properties, and nutritional implications. The use of barley and oat products as well as β-glucan as a food additive continues to increase. This can provide an additional market for barley and oats, thus increasing the value of the crops.