The structure and function of Gene's organ and its associated glands in ticks

The objective of the study is to provide information on tick reproduction of use in designing new pest control methods. This is the first study to describe the structure of Gene's organ, the egg-waxing organ in ticks, using electron microscopy. Both ultrastructural and physiological aspects are investigated in two important pest species, Boophilus microplus and Amblyomma variegatum. The organ performs an essential function in females by coating the eggs with a waterproofing wax layer during oviposition, which prevents desiccation of the embryo, ensuring its viability. It is therefore a potential target for control agents. The external part of the organ, the 'horns', is an evertable balloon-like cuticular sac which is inflated by fluid pressure and manipulates each egg coating it in wax. The wax passes through pores in the cuticle from the internal lumen. The wax is synthesised by three types of epidermal glands, the tubular, lobular, and accessory glands. The ultrastructure of the gland cells is consistent with their wax secretory function. Biochemical study using radiolabelled acetate shows that label is incorporated into wax lipids by the glands, and the composition of the lipids extracted from the secretory cells was similar to that of the egg wax. Wax synthesis by Gene's organ was disrupted by precocene treatment, which had a cytotoxic effect on the secretory cells and caused egg desiccation. The effects of a range of drugs on oviposition was tested; octopamine and certain adrenergic agonists were found to stop oviposition in engorged females in a similar manner to sublethal doses of formamidine acaricides. Tick muscle has received few previous investigations, so the present study also concerns the ultrastructure and electrophysiology of the retractor muscles controlling the horns and their innervation. Evidence is presented implicating L-glutamate and L-aspartate as excitatory transmitters at the neuromuscular junctions.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

Thames Polytechnic

Year dc:date.issued

2017

Author dc:creator

• Booth, Timothy Franklin

Advisor dc:contributor.advisor

• Hart, R. J.

• QP Physiology

Language dc:language

en