In response to crowding, locusts develop characteristic black patterns that are well discernible in the gregarious phase at outbreaks. We report here a dark-colorinducing neuropeptide (dark-pigmentotropin) from the corpora cardiaca of two plague locusts, Schistocerca gregaria and Locusta migratoria. The chromatographic isolation of this neuropeptide was monitored by using a bioassay with an albino mutant of L. migratoria. Body-color polymorphism is widespread among animals. Two locust species, Schistocerca gregaria and Locusta migratoria, display conspicuous differences in body color, particularly during the nymphal stage. A major extrinsic factor influencing locust body color is phase polymorphism, a term used to describe continuous polymorphism in response to population density: locusts at a low density (solitary phase) are often green or brown, whereas those at outbreaks (gregarious phase) develop black patterns (1-4). Although the role of juvenile hormone in the induction of the green color is well established (2-4), little information is available about the hormonal factor that induces dark color in locusts. It has long been known that some factor present in the brain and the corp cardiaca (CC) promotes darkening in locusts (2, 3), but progress in identifying its chemical nature has been hampered by the lack of a convenient bioassay.Recently, we discovered an albino mutant, originating from a laboratory colony of an Okinawa (Japan) strain of L. migratoria (5). Albinism in this mutant is controlled by a single recessive Mendelian unite (5), as described also for other albino mutants of this species (6, 7), as well as of S. gregaria (8) and the grasshopper Melanoplus sanguinipes (under the name Melanoplus bilituratus) (9). The albinism in the Okinawa strain of L. migratoria is caused by the deficiency of a peptide(s) present in the central nervous system and the CC. Implantation of a brain or CC taken from normal (pigmented) individuals or injection of their methanolic extract induces dark color in albino locusts (10-12), but injection of such methanolic extract made from albino individuals has no dark-colorinducing effect in albino locusts (11). Of interest, implantation of brains or CC taken from other taxa, including S. gregaria and other acridids, cockroaches, katydids, crickets, and moths also are effective in inducing dark color in albino L. migratoria (10,12,13). This result indicates that similar substances inducing dark color in L. migratoria may exist in diverse groups of insects. Because whitish albino locusts can be obtained easily by mass rearing, they provide an excellent bioassay system for the characterization of this dark-color inducing peptide. Its role in body color polymorphism and phase polymorphism in locusts can then be determined by means of the synthetic analog. MATERIALS AND METHODSInsects and Tissue Extraction. The colony of the desert locust S. gregaria was maintained according to Ashby's method (14) and that of the migratory locust L. migratoria migratorioides as described...

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Understanding the acantholytic pathways leading to blistering in pemphigus vulgaris (PV) is a key to development of novel treatments. A novel paradigm of keratinocyte damage in PV, termed apoptolysis, links the suprabasal acantholytic and cell death pathways to basal cell shrinkage rendering a 'tombstone' appearance to PV lesions. In contrast to apoptolysis, the classic keratinocyte apoptosis mediating toxic epidermal necrolysis causes death and subsequent sloughing of the entire epidermis. Apoptolysis includes five consecutive steps. Current pemphigus research is elucidating new mechanisms of keratinocyte detachment in pemphigus vulgaris (PV) that lead to blistering. Identification of the key pathophysiologic elements will facilitate pharmacologic development of agents to prevent this breakdown in epidermal integrity. The classic studies demonstrating that PVIgG can induce suprabasal acantholysis -a histopathologic hallmark of PV -even in the skin of neonatal mice lacking either desmoglein (Dsg) 3 (1), plasminogen activator (2), or complement activity (3) narrowed the search for the pathophysiologically relevant targets. The results of the study by Pretel et al. (4) published in this issue of Experimental Dermatology underscore the most important pathophysiologic mechanisms in skin of PV patients. In a series of elegant experiments, these authors convincingly demonstrate that acantholysis in PV develops secondary to the PVIgGinduced EGF receptor (EGFR) ⁄ Src signalling that activates an apoptotic cascade through the serine ⁄ threonine protein kinase, mTOR. Furthermore, the suprabasal split occurs due to differences between basal and suprabasal cells in their responses to PVIgG, as was predicted by the Basal Cell Shrinkage hypothesis (5). The data presented by Pretel et al. (4), taken together with a bulk of in vitro and in vivo results reported in the literature, establish a novel paradigm where PVIgG signalling links the suprabasal acantholytic and apoptotic pathways to basal cell shrinkage. In marked

For the process of aging in epidermal cells to be characterized, the status of oxidized and damaged protein accumulation and removal by the proteasome has been investigated. Modified protein content and proteasome activity were assayed in lysates of epidermal cells from donors of different ages. Increased levels of oxidized proteins, glycated proteins, and proteins modified by the lipid peroxidation product 4-hydroxy-2-nonenal were observed in cells from old donors. At the same time, a decline of chymotrypsin-like and peptidylglutamyl-peptide hydrolase activities of the proteasome was found in aging keratinocytes. This age-related decline of the proteasome peptidase activities can be explained, at least in part, by a decreased proteasome content as observed by immunoblotting and enzyme-linked immunosorbent assay. In keratinocyte cultures, a decrease of proteasome activity and content was observed upon serial passaging. In cultures, as well as in skin, an inverse relationship was found between the aging marker 1-galactosidase and the proteasome content. These results suggest that proteasome is downregulated during replicative senescence as well as in aged cells in vivo, possibly resulting in the accumulation of modified proteins.