Hormone exogenously applied

Although, ecdysteroids occur in helminth tissue and affect a number of aspects of development, the true hormonal role of ecdysone in helminths remains to be documented. Insect juvenile hormones (JH) have also been implicated as regulators of nematode development, particularly in relationship to molting and exsheathment, but there is little analytical evidence supporting the occurrence of JH in nematodes. However, exogenously applied JH and synthetic JH analogs have been reported to alter developmental processes of nematodes (71-73). A concerted effort to apply modern analytical methods could resolve the question of the presence of insect JH in nematodes. 

Do exogenously applied hormones induce physiologically significant responses in lower plants ... 

Although it is virtually impossible to do ideal experiments with intact plants, certain considerations should be kept in mind in all experiments. Manipulations of whole plants are at best disruptive. Specifically, cutting a plant or plant part will inevitably produce a wound response and in addition it will interrupt hormonal signals which would have been received in the intact plant. Replacing plant parts with variously applied hormones may lead to the presence of the hormones in unnatural places, and to unusual metabolism of these hormones both at the cut surface and within the plant. In addition exogeneously applied hormones may increase an endogenous pool to the point of producing hormone imbalance and metabolic disturbance. 

Two female sex hormones, estradiol-17 and progesterone, and one male sex hormone, testosterone, are used as growth promoters on beef cattle (Fig. 7.1). By nature, they are all endogenous products playing an important role in controlling reproductive functions in humans and animals. When applied exogenously they will enter the same metabolic pathways as the endogenously produced molecules. 

Oligogalacturonides have been suggested to act as mobile wound hormones, switching on the synthesis of protease inhibitors in several leaves of a tomato plant in response to a localised injury in one leaf [56]. In experiments carried out to test the mobility of pectic fragments within the plant, exogenous C-labelled pectic polysaccharides and H-labelled oligogalacturonides were applied to wound-sites on tomato leaves. The radioactivity moved towards the tip and margins of the leaf (a pattern characteristic of the xylem stream... 

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