In Locusta migratoria, activation of phenoloxidase in the haemolymph in response to injection of laminarin is age-dependent: being absent in fifth instar nymphs and newly emerged adults, and only becoming evident four days after the final moult. This pattern of change in phenoloxidase activation correlates with the pattern of change in the concentration of apolipophorin-III (apoLp-III) in the h...

In insects, the enzyme phenoloxidase (PO; EC 1.14.18.1) forms an integral part of the cellular and humoral defence system in response to foreign organisms. This enzyme has been shown to have at least two functions. Firstly, to synthesise melanin which encapsulates the invaders and, secondly, as a recognition system for generating other components of the host defence system. In a study with Euro...

Excessive melanin formation has been linked to various skin disorders such as hyperpigmentation and cancer. Tyrosinase is the most prominent target for inhibitors of production. In this study, we investigated whether arbutin its prodrug, undecylenic acid ester, might inhibit phenoloxidase (PO), a tyrosinase-like enzyme. Molecular docking simulation results suggested that ester can bind substrat...

The development of phenoloxidase during amphioxus embryogenesis was spectrophotometrically and histochemically studied for the first time in the present study. It was found that (1) PO activity initially appeared in the general ectoderm including the neural ectoderm and the epidermal ectoderm at the early neurula stage but not in the mesoderm or the endoderm, and (2) PO activity disappeared in ...

1. Pheromones are chemical signals that function not only as mate attractors, but may also relay important information to prospective mates. In order for the information to be reliable, the signal must be costly to produce and this is likely to result in condition dependent expression of the signal. 2. We present results from two experiments on the grain beetle Tenebrio molitor examining phenot...

In the past decades, shellfish culture has developed in a significant way around the world. However, culture areas are often subject to recurring anthropic pollution. The recrudescent presence of industrial wastes is a source of heavy metals and results in pollutant transfer towards the aquatic environment in estuarine areas. Because of their mode of life, bivalves, including mussels and oyster...

The strength of selection on immune function in wild populations has only been examined in a few vertebrate species. We report the results from a study measuring selection on a key insect immune enzyme, phenoloxidase (PO), in a wild population of the damselfly Calopteryx xanthostoma. We followed individually marked males from the pre-reproductive adult phase and recorded their lifetime mating s...

Explanations for the evolution of pathogen-induced fecundity reduction usually rely on a common principle: the trade-off between host longevity and reproduction. Recent advances in nutritional research have, however, challenged this assumption and shown that longevity and reproduction are not inextricably linked. In this study, we showed that beetles infected by cysticercoids of the tapeworm Hy...