Artificial UV-B induced changes in pigmentation of marine diatom Coscinodiscus gigas.

In vitro studies in marine diatom Coscinodiscus gigas revealed that artificial UV-B radiation (313 nm) at a dose level of 0.4W m(-2) for a continuous period of 3 hours in a UV treatment chamber caused disbursement of chromatophores from their normal loci and resulted in clumping / aggregation of chromatophores exhibiting a phenomenon called UV-B induced syntrophism. It is also understood that such clumping could cause only insignificant reduction in photosynthetic oxygen release.

Effect of water extract of the bark of Buchanania lanzan linn. on behaviour and chromatophores of a fresh water fish, Labeo rohita.

Fish exposed to 150 ppm and 250 ppm doses saparately, showed eratic swimming with hyper-excitability, spiralling, convulsion and mortality. However at 350 ppm dose fish became lethargic and steady at the bottom of aquarium. This behaviour appears to be due to sedative effects of fish implicating the phychoactive nature of the plant B. Ianzan. At 150 ppm to 350 ppm doses, fish scale changed from reticulate to punctate chromatophores; and treated fish when transferred to fresh water, were slowly regained to normal behaviour after 96 h exposure. Hence doses regaining from 150 ppm to 350 ppm is considered to be psychoative in nature. In higher doses 450 ppm and 550 ppm fish could survive only 76 h and 4.30 h respectively and then died indicating toxicity of plant for the said doses. It is found that scale present on its body is most suitable test system for the study of psychoactivity and toxicity of plant extracts on fish, Labeo rohita.

Cellular signalling in vertebrate pigment cells

Chromatophores are specialized integumental stellate cells that synthesize and store pigments. Pigment granules are translocated within chromatophores of poikilothermic vertebrates and crustaceans in response to photic, thermal and/or neurohormonal stimuli, allowing the animal to rapidly change color for thermoregulation, adaptation to light and background, and social behavior display. Birds and mammals do not show color changes, but may present slow long-term responses, such as melanocyte proliferation, melanin synthesis and melanin granule translocation into feathers, hair and surrounding keratinocytes. Pigment translocation in lower vertebrates as well as pigment production in all vertebrates are modulated by a variety of hormones and neurotransmitters acting on transmembrane receptors located on the cell surface. Alpha-melanocyte-stimulating hormone (alpha-MSH), melanin-concentrating hormone (MCH), melatonin and catecholamines are the most important pigment cell agonists in vertebrates. The major signalling pathway leading to pigment dispersion and melanin synthesis appears to involve stimulation of adenylate cyclase followed by an increase in the cAMP level and activation cAMP-dependent protein kinases (PKAs). Another melanogenesis related intracellular pathway involves the activation of protein kinase C (PKC) by diacylglycerol, and the increase in cytosolic Ca2+ by inositol triphosphate. Growth factors such as basic fibroblast growth factor (bFGF), hepatocyte growth factor (HGF) and mast cell growth factor (MGF or KIT tigand), and UV radiation modulate the melanogenic and mitogenic processes in vertebrates melanocytes as well.

Relación entre desplazamiento de melanosomas y cambios de color en lagartijas machos: liolaemus tenuis tenuis: un estudio ultraestructural / Relationship between melanosomes displacement and color change in male lizards: liolaemus tenuis tenuis: an ultrastructural study

La mayor parte de los organismos multicelulares se caracterizan por un patrón de color distintivo y, a menudo, particular. Uno de los efectores relacionados con el proceso corresponde a células especiales, los cromatóforos. En este trabajo se demuestra mediante técnicas de microscopía electrónica, que en el dermis de reptiles sometidos a 35§C por 12 min, se produce una fuerte concentración de melanosomas en torno al núcleo de los melanóforos. Por el contrario, a 0§ los melanóforos presentan expansiones citoplasmáticas que contienen numerosos melanosomas. Asociados a los melanosomas en dispersión, se observan microtúbulos. Esta característica permite plantear la posible existencia de algún tipo de relación entre microtúbulos y movimiento de melanosomas en este reptil, cuando es sometido a bajas temperaturas, momento en que se oscurecen. Se destacan también, gruesos manojos tridimensionales de fibras colágenas asociadas a fibroblastos, estructuras, que para algunos autores, representarían un primordio de esclerificación dérmica, fenómeno que predecería a la fase fibrilar de la osificación dérmica o directa. Otro tipo de célula, los iridóforos, contienen placas reflectantes que reflejan la luz en direcciones determinadas

Estudo histológico das glândulas lombares de Pleurodema thaul (Amphibia, Anura, Leptodactylidae) / Histologic study of lumbar glands of Pleurodema thaul (Amphibia, Anura, Leptodactylidae)

As räs da espécie Pleurodema thaul possuem duas protuberâncias cutâneas dorsolaterais, uma de cada lado do corpo, em posiçäo imediatamente posterior ao sacro. Essas protuberâncias, denominadas glândulas lombares, foram estudadas histologicamente verificando-se que seus cromatóforos apresentam-se, sobretudo, dispostos organizadamente logo abaixo da epiderme, constituindo uma unidade cromatofórica dérmica. Como outras macroglândulas de anuros, as protuberâncias lombares säo constituídas principalmente pelo acúmulo de alvéolos granulosos repletos de secreçäo. A prsença de alvéolos granulosos e a organizaçäo cracterística dos cromatófaros dérmicos permitem sugerir um papel defensivo para as glândulas lombares. Na maioria dos anfíbios, os alvéolos granulosos acumulam uma secreçäo tóxica para diversos vertebrados. Os cromatóforos, nesta espécie, talves desempenhem uma funçäo apossemática pois sua disposiçäo na pele faz com que as glândulas lombares se assemelhem a olhos, dando, possivelmente, a um eventual predador da espécie em questäo, a impressäo de que se trata de animal de maiores dimensöes

Nosologic Study of Nevus Spilus (Speckled lentiginous lnevus) / 대한피부과학회지

The nevus spilus, also called speckled lentiginous nevus, presents itself as a patch of melanization dotted by smaller macules of darker color, frequently occuring on the trunk, and in some respect, resembeing the cafe au lait of von Recklinghausens disease and Albrights syndrome. We present clinical and histopathologic observation made on 14 patients, 13 male and 1 female, who agreed to go through a biopsy, during 5 years period from 1975 to 1980. The age at the visit ranged from 11 years to 61, with a mean of 22. 4. The location of lesions were shouIder (in 5 cases), neck (in 2), back (in 2), trunk (in 4),arm (in 1), and buttock (in 1). The epidermal changes consist of hypererkatosis (in 7), acanthosis (in 6), elongation of rete ridge and papillomatosis (in 9), basilar hypermelanosis (in 14), and nevus cell nests(in 3) The dermal changes consists of mild perivascular lymphoid and histiocytic cellular infiltrations (in 11), chromatophores (in 8) and dilated blood vessels (in 6). It is suggested that nevus spilus should be considered as a giant lentigo, a neoplasia of epictermal melanocytes, where junctional nevus is to develop.

Histology of Secondary Syphilid / 대한피부과학회지

Fundamental pathologic cianges of secondary syphilid are said to be swelling and proliferation of endothelials and a predominantly parivascular infiltrates composed chiefly of lymphoid cells and plasma cells. But recentIy this theory has heen challenged. We present bistologic observation made on 10 patients who agreed to go through a biopsy, during 2 years period. from 1975 to l977. Male to female ratio was 9: 1 The age of patient ranged from 20 to 33, with a mean of 26. 8. The duration of lesion before the visit to the department ranged frorn 6 weeks to 20 weeks, with a mean of 11.9. The lesions in 2 were classified as macule, 3 as papule (1 as moist papule), and 5 as papulo-squamous lesions. The VDRL titer was higher in papular type. Dark fieId examination was performed on all patient and 6 showed positive result. The edidermal changes consist of hyperkeratosis (in 6 cases), parakeratosis (in 5), acanthosis (in 6), elongation of rete ridges (in 8) and exocytosis (in 3). The dermis showed mild to severe perivascular infiltration consist chiefly of lymphoid cells and histiocytic cells (in 10), plama cells (in 7), eosinophils (in 4), neutrophils (in 2), chromatophores (in 4), extra vasation of RBC (in 5), and dilated bload vessels endothelial swellings (in 8). Of particular interest was the finding that plasma cell infiltration is more pronounced at the lower portion of dermal infiltrate and in 3 cases plasma cell infiltration was totally absent. Vascular changes were seen in 8 cases.