Molecular and Cellular Endocrinology 168 (2000) 101 – 109 The pigmentotropic hormone [His 7 ]-corazonin, absent in a Locusta migratoria albino strain, occurs in an albino strain of Schistocerca gregaria Liliane Schoofs a, *, Geert Baggerman a , Dirk Veelaert a , Michael Breuer a , Seiji Tanaka b , Arnold De Loof a a Laboratory of Deelopmental Physiology and Molecular Biology, K.U. Leuen, Zoological Institute, Naamsestraat 59, Leuen B-3000, Belgium b Department of Insect Physiology and Behaior, National Institute of Sericultural and Entomological Science, Tsukuba, Ibaraki 305 -8634, Japan Received 2 March 2000; accepted 15 June 2000 Abstract [His 7 ]-corazonin has recently been identified in the corpora cardiaca (CC) of two locust species, the migratory locust, Locusta migratoria and the desert locust, Schistocerca gregaria, as the dark colour inducing neurohormone. Here, we investigate whether [His 7 ]-corazonin occurs in the brain-CC axis of a Schistocerca albino strain. From data obtained by immunocytochemistry, injection experiments, chromatographic and mass spectrometric analysis of brain and CC tissues, it could be concluded that an albino strain of S. gregaria from Denmark contains authentic [His 7 ]-corazonin. This was unequivocally demonstrated by sequencing the [His 7 ]-corazonin-immunoreactive factor in albino Schistocerca brain-CC extracts with ESI-Qq-oa-TOF mass spectrometry. Albinism in this strain is hence not caused by the deficiency of authentic [His 7 ]-corazonin in the brain-CC axis, nor by defects in release. Conversely to L. migratoria albinos, injection of [His 7 ]-corazonin failed to induce dark pigmentation in Schistocerca albinos. Therefore, albinism in the investigated Schistocerca strain is likely to be situated at the level of the receptor, signal transduction mechanisms or of pigment biosynthesis. © 2000 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Albinism; Dark colour inducing hormone; Corazonin; Electrospray ionisation double quadrupole time of flight mass spectrometry; Schistocerca gregaria ; Corpora cardiaca www.elsevier.com/locate/mce 1. Introduction Pigments of the skin play a decisive role in the protection, attraction and/or camouflage of an organ- ism. Geographical areas of high humidity, sunshine or UV-irradiation in general have more deeply pigmented animals than areas with less sunshine which illustrates that skin pigmentation is very important for the adap- tation of an animal to its environment. In Amphibia it has been recognized several decades ago that the pitu- itary peptide hormone, melanophore-stimulating hor- mone (MSH), accounts for the darkening of the skin in response to a black background. Since then, the biolog- ical effect of MSH on skin pigmentation was studied extensively in vertebrates (Bunel et al., 1992; Vallarino et al., 1998; Je ´gou et al., 1993). In response to crowding, locusts develop characteris- tic black patterns, which are well discernible in the gregarious phase at outbreaks. Recently, we isolated and identified [His 7 ]-corazonin in the corpora cardiaca (CC) of two locust species, Locusta migratoria and Schistocerca gregaria, as the hormonal factor responsi- ble for the production of melanin in the insect’s cuticle and the normal dark body colour pattern, typical for the gregarious phase (Tawfik et al., 1999). An albino mutant strain of L. migratoria which originates from a laboratory colony of an Okinawa (Japan) strain, was used as a bioassay system to monitor the pigmen- totropin during HPLC purifications. Injections of 10 pmol [His 7 ]-corazonin or higher concentrations caused these albino mutants to turn completely black. Intrigu- * Corresponding author. Tel.: +32-16-324577; fax: +32-16- 323902. E-mail addresses: liliane.schoofs@bio.kuleuven.ac.be (L. Schoofs), stanaka@nises.affrc.go.jp (S. Tanaka). 0303-7207/00/$ - see front matter © 2000 Elsevier Science Ireland Ltd. All rights reserved. PII: S0303-7207(00)00306-3