Neuromuscular function in phytophagous insects
Başlık:
Neuromuscular function in phytophagous insects
Yazar:
Belton, Peter, author.
ISBN:
9780438057869
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (137 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Advisors: P. N.R Usherwood.
Özet:
The ionic composition of the haemolymph of many phyto-phagous insects is toxic to frog nerve-muscle preparations. This observation and others have given rise to much speculation on the role of common cations in setting up electrical potentials in phytophagous Lepidoptera and Coleoptera.There are marked differences between frogs and phytophagous insects in the concentrations of ions surrounding the nerves and muscles, yet their electrical activity in a normal environment is similar. There appear to be three main reasons for this electrical similarity: the first is discussed critically and the last two provide material for the experiments described in the thesis. Insect nerve fibres are provided with an environment similar to that of frog axons as a result of the active movement of ions by glial cells. The neuromuscular synapses of phytophagous insects are protected anatomically like the axons, and probably also chemically by glial and muscle cells. The muscle fibre membrane of insects can utilize a variety of cations to bring about depolarization. Magnesium ions can, and probably do in nature, enter the muscle fibre of phytophagous insects during the action potential. Potassium ions leave the fibres during the repolarizing phase of the action potential. Changes in the external potassium concentration have little effect on the resting potential but rapidly affect the falling phase of the action potential. When the electrochemical gradient for potassium is reversed, potassium ions can enter the muscle fibres of mealworms and give rise to a spike while the resting potential remains close to its normal value. This anomalous difference in the behaviour of the resting and action potentials can be explained by assuming that the former is maintained more or less directly by the metabolism of muscle cells. It is argued that a simpler explanation involves the resting and action potentials being set up independently across different regions of the muscle fibre, as they may also be in the fast muscle fibres of the frog. Equipment was designed for this work and comparative experiments were carried out on slow skeletal muscle fibres of the frog and visceral muscle fibres of the cockroach, which have features in common with each other as well as with the fibres of the other phytophagous insects investigated.
Notlar:
School code: 0547
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(684645.1) | 684645-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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