Identification of Polymorphism in the MC1R Gene and Its Association with the Melanin Content in Feathers of Chinese Yellow Quails

MC1R plays a crucial role in controlling the type of melanin synthesized in the melanocytes, which greatly affects plumage color in birds. One g.16796362G/T SNP was found in the MC1R gene coding region, which caused a Met120Ile mutation in the amino acid sequence. The Met120Ile mutation was located in the third transmembrane domain of the MC1R protein and decreased protein stability. The g.16796362G/T locus achieved medium polymorphism and had significant association with feather melanin content in Chinese yellow quails. The contents of total melanin and pheomelanin with AA genotype were significant lower than those with AB or BB genotypes in skin tissues, while the expression levels of MC1R mRNA had no significant difference in feathers with different genotypes. This experiment indicated that the Met120Ile mutation could affect the function of the MC1R protein and change the biosynthesis of melanin in Chinese yellow quails.(AU)

Licorice zinc suppresses melanogenesis via inhibiting the activation of P38MAPK and JNK signaling pathway in Balb/c mice skin

Purpose: The active melanocytes in the skin were affected by hormones and ultraviolet (UV) irradiation. Licorice zinc has a whitening effect, which may have a prominent potential in the treatment of pigmented skin disease. Methods: Modeling chloasma C57BL/6J mice by daily progesterone injection (15 mg/kg) and ultraviolet B (UVB) irradiation (λ = 312 nm, 2 h/day) for 30 days. Then, mice were given 0.65, 1.3, and 2.6 (g/kg) of licorice zinc and tranexamic acid 250 mg daily by oral administration for 14 days, respectively. Hematoxylin and eosin and Fontana-Masson staining, and Western blotting (WB) were performed to test the inhibitory of melanogenesis and activation of c-Jun-N-terminal (JNK)/p38 mitogen-activated protein kinases (MAPK) for licorice zinc. Melanogenesis was induced by α-melanocyte-stimulating hormone in vitro. Cell counting kit-8, melanin content determination, and WB were performed to verify the inhibitory effect of licorice zinc on melanogenesis. Results: The present study showed that licorice zinc decreased melanin formation, cutaneous tissue injury, and the phosphorylation of JNK and P38MAPK, which was caused by UVB irradiation in vivo. In vitro, licorice zinc showed opposite effects from JNK/p38 activator. Meanwhile, tyrosinase-related protein-1, tyrosinase, and microphthalmia-associated transcription factor were decreased too. Conclusions: Licorice zinc induced a decrease in melanin synthesis by inhibiting the JNK and the P38MAPK signaling pathway, suggesting licorice zinc is a potential agent of anti-chloasma.

Melanomas em cães no Sertão do Nordeste do Brasil - epidemiologia, fatores de risco e achados clinicopatológicos / Melanoma in dogs in the backlands of Northeastern Brazil - epidemiology, risk factors and clinicopathological findings

Background: Melanoma is a malignant neoplasm that arises from melanocytes and malanoblasts. It is also more frequently reported in dogs than in other species. They may arise from melanocytes in the skin, on the surfaces of the mucous membranes, and eyes. The aim of this study was to describe the epidemiological aspects, risk factors and clinicopathological findings of melanoma in dogs in the backlands, northeastern Brazil. Materials, Methods & Results: A retrospective study was carried out in all biopsy samples and necropsy examinations of dogs, from January 2003 to December 2021, at the Animal Pathology Laboratory of the Federal University of Campina Grande, Patos, Paraiba, northeastern Brazil. Epidemiological data, clinical signs, and gross lesions were reviewed from the diagnostic laboratory reports. Samples of the skin, lymph nodes, central nervous system and organs of the thoracic and abdominal cavities were fixed in 10% buffered formalin, processed routinely for histopathology, embedded in paraffin wax, cut into 4 µm sections, and stained with hematoxylin and eosin (HE). Histological sections were also submitted to immunohistochemistry with the primary antibody anti-Melan A. Of the 4717 records found, 1158 (24.5%) were diagnosed with neoplasms, of which 48 (4.14%) cases were of melanoma. Of this total, 28 (58.3%) dogs were elderly, 19 (39.6%) were adults, and 1 (2.1%) was young. Mixed breed animals were the most affected (42.6%), followed by the pinscher breed (19.1%). According to the anatomical region, the most affected site was the skin (38/53=71.7%), followed by the oral cavity (12/53=22.65%) and the eyes (3/53=5.7%). Grossly, the skin lesions were characterized by exophytic and usually blackened, sometimes irregular and firm, nodules. At cut, they had a smooth, compact and blackened surface. Lesions in the oral cavity were characterized by blackened, irregular and infiltrating nodules or masses. The ocular lesions were always unilateral and were characterized by an enlarged and diffusely blackened eyeball, with areas of ulceration and subversion of tissue architecture. In 5 animals there was more than one anatomical site affected, totaling 53 lesions. In 9 (17%) cases, metastases were identified, 8 in regional lymph nodes and 1 in the lung. Histopathology showed a densely non-encapsulated, poorly delimited, expansive and infiltrative neoplasm, composed of neoplastic cells arranged in islands or nests and supported by fibrovascular stroma, containing a variable amount of brownish pigment (melanin). Immunohistochemistry showed strong immunostaining of the neoplastic cells in brown by the anti-Melan A antibody. Discussion: The diagnosis of melanoma was established based on epidemiological, clinical, anatomopathological, and immunohistochemical findings. Gender is not a predisposing factor, and although there was no statistically significant relationship, males were more affected. Senescence is a conditioning risk factor. Elderly animals were more affected (P < 0.0001) than adult ones, with OR = 4.38; and young ones (P = 0.0051), with OR = 12.65. Some breeds, especially those with marked skin pigmentation, were more affected, however the most affected ones in this survey were pinscher and poodle. Cutaneous melanoma accounted for almost 72% of cases, contesting recent studies where oral cavity melanoma was more frequent. Therefore, it is believed that the climatic conditions of the backlands sub-region, in northeastern Brazil, associated with the individual characteristics of the dogs, are involved in the development of these neoplasms, since the climate is predominantly dry, with high temperatures throughout the year, with maximums that can reach 40ºC, favoring the exposure to high incidence of ultraviolet radiation.

Cryosurgery using dimethyl ether in the treatment of pigmentary keratitis in pug dogs / Criocirurgia usando o dimethyl ether no tratamento da ceratite pigmentar em cães da raça Pug

Corneal pigmentation and vascularization eventually result in blindness in dogs. Pigmentary keratitis describes a relatively common presentation comprising the deposition of melanin in the cornea and conjunctival surface associated with chronic inflammation. Cryosurgery is indicated as a treatment for pigmentary keratitis in dogs. Due to melanocytes sensitivity to cold, cryosurgery is a viable treatment for severe refractory corneal pigmentation. The aim of this work was to evaluate the use of dimethyl ether in the treatment of pigmentary keratitis in 14 eyes of seven Pug dogs. Follow-up occurred after 30 days in four animals and six months in three animals. In all treated animals, there was a reduction in corneal pigmentation. Cryosurgery causes intracellular and extracellular ice crystal formation and other mechanisms that result in rupture and death of the melanocytes. The technique used was easy to perform, has a low cryogen cost and has few undesirable or serious side effects. However, after 30 days repigmentation occured in treated patients. Cryosurgery shows good results in the first four weeks, but partial recurrence occurred in all cases.

A pigmentação e a vascularização da córnea eventualmente resultam em cegueira em cães. A ceratite pigmentar é descrita com uma apresentação relativamente comum que compreende a deposição de melanina na córnea e na superfície conjuntival associada à inflamação crônica. A criocirurgia é indicada como tratamento para ceratite pigmentar em cães. Devido à sensibilidade dos melanócitos ao frio, a criocirurgia é um tratamento viável para pigmentação corneana refratária grave. O objetivo deste trabalho foi avaliar o uso do éter dimetílico no tratamento da ceratite pigmentar em 14 olhos de sete cães da raça Pug. O acompanhamento foi de 30 dias em quatro animais e seis meses em três animais. Em todos os animais tratados, houve redução da pigmentação da córnea. A criocirurgia causa a formação de cristais de gelo intracelular e extracelular e outros mecanismos que resultam na ruptura e morte dos melanócitos. A técnica utilizada foi de fácil execução, baixo custo de criogenia e poucos efeitos colaterais indesejáveis ou graves. No entanto, após 30 dias, ocorreu repigmentação nos pacientes tratados. A criocirurgia apresenta bons resultados nas primeiras quatro semanas, mas ocorreu recidiva parcial em todos os casos.

Systemic phaeohyphomycosis in a dog caused by Cladophialophora bantiana

Background: Cladophialophora bantiana is a dematiaceous fungus that causes phaeohyphomycosis, a generic term used to describe a variety of unusual mycoses caused by fungi that have melanin in their cell wall. C. bantiana targets the central nervous system, commonly causing localized brain infections that may result in disseminated infections. In Brazil, minimal phaeohyphomycosis data are available, and information about C. bantiana infections in animals, especially canines, is scarce. Thus, the aim of this study was to describe the clinical and pathological aspects of systemic phaeohyphomycosis caused by C. bantiana in a dog. Case: A 1-year-old female Pit Bull presented with weight loss, reduced appetite, and a history of cutaneous lesions on the right thoracic limb; however, clinical evolution was not reported. The bitch had reportedly given birth recently. Physical examination revealed thinness, pale ocular and oral mucosa, submandibular lymph nodes, and enlarged popliteal lymph nodes. The bitch died after convulsive crises during hospitalization. At necropsy, white-yellowish multifocal nodules were observed in the liver and right kidney. The brain featured left cerebral hemisphere asymmetry with blood vessel congestion in the leptomeninges and an irregular brownish focal area on the surface of the right occipital cortex. Cross-sections of the formalin-fi xed brain exhibited compression of the left lateral ventricle and the presence of grayish and friable multifocal areas in the gray matter of the left parietal and right occipital cortices. Fragments of the lesions were collected for histopathological and microbiological examination. Histologically, the lesions were similar, characterized by hepatitis, nephritis, and granulomatous and necrotizing...

Dermatitis seborreica en tapir albino (Tapirus terrestris) / Seborrheic dermatitis in albino lowland tapir (Tapirus terrestris) / DERMATITE SEBORREICA EM ANTA ALBINA (Tapirus terrestris)

El albinismo es una anomalía genética recesiva en la que la produccíon de la melanina está reducida o ausente, lo que interfiere com la  pigmentación de la piel, pelaje y los ojos de los individuos. Se considera un fenómeno natural raro, principalmente en animales salvajes. Los albinos son muy susceptibles al daño de la piel por el sol, ya que la exposición acumulada a los rayos ultravioleta (UV) puede ser dañina. Este reporte discute la ocurrencia de seborrea seca en un tapir albino (Tapirus terrestris), mantenida bajo cuidado humano. La seborrea seca es una enfermedad crónica de la piel en la que falla la queratinización de la epidermis, formándose descamaciones excesivas y alterando la oleosidad de la piel y la pelaje. El tratamiento clínico instituido se basó en la aplicación tópica de uma solución dermatológica hidratante en spray y em la modificación del recinto para reducir la incidencia de la luz solar sobre el individuo.  El resultado fue satisfactorio y tuvo como ayuda un miscroscopio digital portátil que se utilizó periódicamente hasta la recuperación del animal.

Albinism is a recessive genetic disorder in which melanin prodution is reduced or absent, interfering with pigmentation of the skin, hair and eyes of individuals. It is considered to be of rare natural occurrence, mainly in wild animals. Albino individuals are highly susceptible to skin damage caused by the sun, once cumulative exposure to ultraviolet (UV) rays can be harmful. This report discusses the occurrence of dry seborrhea in an albino lowland tapir (Tapirus terrestris), kept under human care. Dry seborrhea is a chronic skin disease in which there is a failure in the keratinization of the epidermis, forming excessive scales and altering the oiliness of the skin and hair. The clinical treatment instituted was based on topical application of a moisturizing dermatological spray solution and on changes made to the enclosure in order to reduce the incidence of sunlight on the individual. The result was satisfactory and had as na aid a portable digital microscope that was used periodically until the recovery of the animal.

O albinismo é uma desordem genética recessiva em que a produção de melanina é reduzida ou ausente, o que interfere na pigmentação da pele, pelos e olhos dos indivíduos. É considerada de rara ocorrência natural, principalmente em animais selvagens. Indivíduos albinos são altamente suscetíveis a injúrias na pele causadas pelo sol, já que a exposição aos raios ultravioletas (UV) de forma cumulativa pode ser prejudicial. Este relato discorre sobre a ocorrência de seborreia seca em uma anta albina (Tapirus terrestris), mantida sob cuidados humanos. A seborreia seca é uma enfermidade cutânea de caráter crônico em que ocorre falha na queratinização da epiderme, formando excessivamente escamas e alterando a oleosidade da pele e pelos. O tratamento clínico instituído foi baseado na aplicação tópica de solução dermatológica hidratante spray e em mudanças realizadas no recinto a fim de diminuir a incidência de luz solar no indivíduo. O resultado foi satisfatório e teve como auxílio um microscópio digital portátil que foi utilizado periodicamente até a recuperação do animal.

Morphological study of the pineal gland of Alouatta belzebul / Estudo morfológico da glândula pineal de Alouatta belzebul

The pineal is a neuroendocrine gland responsible for the synthesis and release of melatonin. It is present in the brain of vertebrates, but its morphology and location vary considerably among species. For the species Alouatta belzebul, although some anatomical aspects of the nervous system have been described, there is no information on the morphology and histological composition of this gland. Thus, the present study aimed to describe the morphological, morphometric, and histological aspects of the pineal of Alouatta belzebul. Seven adult specimens were dissected from which the location of the gland in relation to the surrounding brain structures was described, and its length and width were measured. Histological slides were then prepared and stained using hematoxylin-eosin and PAS techniques. It was observed that the pineal of Alouatta belzebul is located superior and cranial to the cerebellum, superior to the superior colliculi and below the splenium of the corpus callosum and was classified as sub-callosal. It had an average length of 2.6mm and an average width of 1.14mm. Histologically the gland is composed of irregular strands of pinealocytes and gliocytes. The pinealocytes showed pigments similar to melanin.

A pineal é uma glândula neuroendócrina responsável pela síntese e liberação de melatonina. Está presente no encéfalo dos vertebrados, mas sua morfologia e localização variam consideravelmente entre as espécies. Para a espécie Alouatta belzebul, apesar de terem sido descritos alguns aspectos anatômicos do sistema nervoso, não há informações sobre a morfologia e composição histológica desta glândula. Assim, o presente estudo teve como objetivo descrever os aspectos morfológicos, morfométricos e histológicos da pineal de Alouatta belzebul. Foram dissecados sete encéfalos de espécimes adultos dos quais se descreveu a localização da glândula em relação às estruturas encefálicas circunvizinhas e foram realizadas medidas de comprimento e largura da mesma. Em seguida foram preparadas lâminas histológicas e coradas pelas técnicas de hematoxilina-eosina e PAS. Observou-se que a pineal de Alouatta belzebul localiza-se superior e cranialmente ao cerebelo, superior aos colículos superiores e abaixo do esplênio do corpo caloso e foi classificada como subcalosa. Apresentou comprimento médio de 2,6mm e largura média de 1,14mm. Histologicamente a glândula é composta por cordões irregulares de pinealócitos e gliócitos. Os pinealócitos apresentaram pigmentos semelhante à melanina.

Dermatite seborreica em anta albina (Tapirus terrestris) / Seborrheic dermatitis in albino lowland tapir (Tapirus terrestris) / Dermatitis seborreica en tapir albino (Tapirus terrestris)

O albinismo é uma desordem genética recessiva em que a produção de melanina é reduzida ou ausente, o que interfere na pigmentação da pele, pelos e olhos dos indivíduos. É considerada de rara ocorrência natural, principalmente em animais selvagens. Indivíduos albinos são altamente suscetíveis a injúrias na pele causadas pelo sol, já que a exposição aos raios ultravioletas (UV) de forma cumulativa pode ser prejudicial. Este relato discorre sobre a ocorrência de seborreia seca em uma anta albina (Tapirus terrestris), mantida sob cuidados humanos. A seborreia seca é uma enfermidade cutânea de caráter crônico em que ocorre falha na queratinização da epiderme, formando excessivamente escamas e alterando a oleosidade da pele e pelos. O tratamento clínico instituído foi baseado na aplicação tópica de solução dermatológica hidratante spray e em mudanças realizadas no recinto a fim de diminuir a incidência de luz solar no indivíduo. O resultado foi satisfatório e teve como auxílio um microscópio digital portátil que foi utilizado periodicamente até a recuperação do animal.(AU)

Albinism is a recessive genetic disorder in which melanin prodution is reduced or absent, interfering with pigmentation of the skin, hair and eyes of individuals. It is considered to be of rare natural occurrence, mainly in wild animals. Albino individuals are highly susceptible to skin damage caused by the sun, once cumulative exposure to ultraviolet (UV) rays can be harmful. This report discusses the occurrence of dry seborrhea in an albino lowland tapir (Tapirus terrestris), kept under human care. Dry seborrhea is a chronic skin disease in which there is a failure in the keratinization of the epidermis, forming excessive scales and altering the oiliness of the skin and hair. The clinical treatment instituted was based on topical application of a moisturizing dermatological spray solution and on changes made to the enclosure in order to reduce the incidence of sunlight on the individual. The result was satisfactory and had as na aid a portable digital microscope that was used periodically until the recovery of the animal.(AU)

El albinismo es una anomalía genética recesiva en la que la produccíon de la melanina está reducida o ausente, lo que interfiere com la pigmentación de la piel, pelaje y los ojos de los individuos. Se considera un fenómeno natural raro, principalmente en animales salvajes. Los albinos son muy susceptibles al daño de la piel por el sol, ya que la exposición acumulada a los rayos ultravioleta (UV) puede ser dañina. Este reporte discute la ocurrencia de seborrea seca en un tapir albino (Tapirus terrestris), mantenida bajo cuidado humano. La seborrea seca es una enfermedad crónica de la piel en la que falla la queratinización de la epidermis, formándose descamaciones excesivas y alterando la oleosidad de la piel y la pelaje. El tratamiento clínico instituido se basó en la aplicación tópica de uma solución dermatológica hidratante en spray y em la modificación del recinto para reducir la incidencia de la luz solar sobre el individuo. El resultado fue satisfactorio y tuvo como ayuda un miscroscopio digital portátil que se utilizó periódicamente hasta la recuperación del animal.(AU)

Melanose talâmica em caprinos / Thalamic melanosis in goats

Background: Melanosis is a blackened pigmentation resulting from the accumulation of melanocytes in tissues that are not normally pigmented. This change in the color of the organs occurs due to the agglomeration of melanocytes originating from abnormal migration during embryogenesis and does not cause dysfunction to the affected organ. Although melanosis frequently occurs in several species and affects several organs such as the brain and spinal cord leptomeninges, involvement in the thalamus region is unusual. The objective of this work was to report 2 cases of thalamic melanosis in goats, determining the pathological and histochemical aspects that assist in the diagnosis of this condition. Cases: Two cases of thalamic melanosis in goats were diagnosed. In both cases, the animals had no nervous history disease and clinical signs. The cause of death in cases 1 and 2 was established based on anatomopathological findings and clinical signs being diagnosed with mycoplasmosis and asphyxia, respectively. After fixing and making cross-sections of the brain, a focal lengthy blackened area was observed on the thalamus surface in both cases. Microscopically, lesions in the brain were similar in both cases and exclusively affected the thalamus. These cells had abundant cytoplasm, well delimited with brownish granular pigment. The nuclei were difficult to visualize and in some cells, it was rounded, well-defined, morphologically compatible with melanocytes. Melanocytes were mainly distributed around neurons and often distended the perivascular space of multiple blood vessels. In Fontana Masson staining, the granules in the cytoplasm of these cells stained strongly black. The Prussian Blue, Periodic Acid- Schiff's, Von Kossa, and Giemsa stains were negative, and the pigment remained brown. In the unstained slides, assembled after the deparaffinization and clarification process, it was observed the permanence of cells with blackish-brown pigment in the cytoplasm. In immunohistochemistry, strong immunostaining of pigmented cells with the Anti-MelanA antibodies was observed in both cases. Discussion: The diagnosis of thalamic melanosis in goats was carried out based on the characteristic pathological findings, in which melanin pigments were demonstrated and identified through HE, Fontana-Masson staining, and unstained slides and confirmed by the IHC. The use of complementary histochemical techniques was fundamental for the classification of the pigment as melanin, demonstrating to be an accessible and reliable tool for the diagnosis of pathological processes that lead to the accumulation of pigments and or material in the tissues. The occurrence of melanin in the thalamus may be associated with a failure in the migration of melanoblasts, which would go to the optical pathways or to the thalamus. This erratic migration of melanoblasts can be explained by the fact that the forebrain is the embryogenic origin of the optic and diencephalon pathways. Macroscopically, thalamic melanosis must be differentiated mainly from neoplastic processes such as melanoma and hemangiosarcoma, pigmented fungus infections, Phalaris angusta poisoning, listeriosis, neurocutaneous melanosis, and neuromelanin. It was concluded that thalamic melanosis is an uncommon alteration in goats and although it has been diagnosed as an incidental necropsy finding, should be included in the differential diagnosis of diseases that affect the central nervous system, especially those that have a color change associated with the deposition of pigments in the tissues.

Metastatic melanoma in a Saanen goat: clinical, ultrasonographic and anatomopathological aspects - case report / [Melanoma metastático em cabra Saanen: aspectos clínicos, ultrassonográficos e Anatomopatológicos - relato de caso]

This report describes clinical, ultrasonographic and anatomopathological findings in a case of metastatic melanoma in an adult Saanen goat. Clinically, the goat had apathy, an intra-abdominal palpable firm structure, and exophytic keratinized areas on the skin of the udder. Ultrasound revealed non-encapsulated oval structures, with heterogeneous echogenicity and marked central and peripheral vascularization, and hypoechoic hepatic multifocal to coalescent areas. In the udder, there were non-encapsulated oval structures with heterogeneous echogenicity and hyperechoic center surrounded by hypoechogenic tissue. Grossly, there were black multifocal to coalescent areas in the liver, as well as black nodules in mammary and mesenteric lymph nodes, uterus, spleen, and myocardium. Microscopically, multifocal melanocytic neoplastic proliferation was observed in the dermis and junction of the udder epidermis. Most of the neoplastic cells had cytoplasmic granules of melanin. In the liver there were areas of neoplastic tissue compressing the adjacent parenchyma, with central foci of necrosis, mild desmoplasia, and multifocal infiltration of malignant cells into the adjacent tissues. Similar findings were observed in the mammary and mesenteric lymph nodes, uterus, spleen, and myocardium, which characterized metastatic melanoma. Ultrasonography played a key role for establishing the diagnosis of a metastatic melanoma and helped establish a proper clinical management protocol.(AU)

Este relato descreve os achados clínicos, ultrassonográficos e anatomopatológicos em um caso de melanoma metastático em uma cabra Saanen adulta. Clinicamente, a cabra apresentava apatia, estrutura firme palpável intra-abdominal e áreas exofíticas queratinizadas na pele do úbere. A ultrassonografia revelou estruturas ovais não encapsuladas, com ecogenicidade heterogênea e marcada vascularização central e periférica, além de áreas hepáticas multifocais a coalescentes hipoecoicas. No úbere, havia estruturas ovais não encapsuladas, com ecogenicidade heterogênea e centro hiperecogênico circundado por tecido hipoecogênico. Macroscopicamente, havia áreas pretas multifocais a coalescentes no fígado, bem como nódulos pretos nos linfonodos mamários e mesentéricos, no útero, no baço e no miocárdio; microscopicamente, proliferação neoplásica melanocítica multifocal foi observada na derme e na junção da epiderme do úbere. A maioria das células neoplásicas apresentava grânulos citoplasmáticos de melanina. No fígado, havia áreas de tecido neoplásico comprimindo o parênquima adjacente, com focos centrais de necrose, desmoplasia leve e infiltração multifocal de células malignas nos tecidos adjacentes. Achados semelhantes foram observados nos nódulos linfáticos mamários e mesentéricos, no útero, no baço e no miocárdio, que caracterizaram o melanoma metastático. A ultrassonografia desempenhou um papel fundamental para estipular o diagnóstico de um melanoma metastático e ajudou a estabelecer um protocolo de manejo clínico adequado.(AU)

Use of Giemsa staining for the immunohistochemical counterstaining in canine melanomas: an "old and forgotten" method

Melanoma is a neoplasm originating from melanocytes and represents 7% of skin tumors and the most common in oral cavity of dogs. Melanoma may present melanocytic pigment in its cytoplasm in varying quantity and its characterization by immunohistochemistry (IHC) is challenging due to the use of chromogen diaminobenzidine (DAB) which itself produces a brown product what makes difficult to distinguish from melanin pigment in this technique. To demonstrate a reliable technique, the use of the Giemsa counterstaining was performed in the IHC of melanomas with different degrees of pigmentation for different cytoplasmic, membrane and nuclear markers. The modification in the IHC technique by the counterstaining of Giemsa allows observable differences under the microscope between melanic pigment(in a blue-green stain), while the DAB chromogen will be observed in brown. With this technique, the prognostic and predictive interpretation of markers in canine melanomas may be more reliable in definitions of clinical behaviors and inexperimental analyzes.(AU)

Use of Giemsa staining for the immunohistochemical counterstaining in canine melanomas: an "old and forgotten" method

Melanoma is a neoplasm originating from melanocytes and represents 7% of skin tumors and the most common in oral cavity of dogs. Melanoma may present melanocytic pigment in its cytoplasm in varying quantity and its characterization by immunohistochemistry (IHC) is challenging due to the use of chromogen diaminobenzidine (DAB) which itself produces a brown product what makes difficult to distinguish from melanin pigment in this technique. To demonstrate a reliable technique, the use of the Giemsa counterstaining was performed in the IHC of melanomas with different degrees of pigmentation for different cytoplasmic, membrane and nuclear markers. The modification in the IHC technique by the counterstaining of Giemsa allows observable differences under the microscope between melanic pigment(in a blue-green stain), while the DAB chromogen will be observed in brown. With this technique, the prognostic and predictive interpretation of markers in canine melanomas may be more reliable in definitions of clinical behaviors and inexperimental analyzes.

Regression of dark color in subterranean fishes involves multiple mechanisms: response to hormones and neurotransmitters

ABSTRACT Organisms with source-populations restricted to the subterranean biotope (troglobites) are excellent models for comparative evolutionary studies, due to their specialization to permanent absence of light. Eye and dark pigment regression are characteristics of most troglobites. In spite of the advance in knowledge on the mechanisms behind eye regression in cave fishes, very little is known about pigmentation changes. Studies were focused on three species of the genus Pimelodella. Exemplars of the troglobitic P. spelaea and P. kronei were compared with the epigean (surface) P. transitoria, putative sister-species of the latter. Melanophore areas and densities are significantly lower in the troglobitic species. Evaluating the in vitro response of these cells to adrenaline, acetylcholine and MCH, we observed a reduced response in both troglobites to adrenaline. The same trend was observed with MCH, but not statistically significant. No response to acetilcholine was detected in all the three. Contrary to expectations, even though eye-regression in P. spelaea was much lower than in P. kronei, pigmentation regression was more advanced. Multiple mechanisms of loss showing a mosaic of traits in troglobitic fishes are discussed here.

RESUMO Organismos com populações-fonte restritas ao biótopo subterrâneo (troglóbios) são excelentes modelos para estudos evolutivos comparativos, devido à especialização resultante do isolamento sob um regime seletivo particular, com ênfase na permanente falta de luz. A regressão do olho e da pigmentação são características dos troglobites. Apesar do avanço do conhecimento sobre os mecanismos subjacentes à regressão ocular em peixes de caverna, pouco se sabe sobre mudanças de pigmentação. Os estudos foram focados em três espécies do gênero Pimelodella. Exemplares das espécies troglóbias P. spelaea e P. kronei foram comparados com a epígea P. transitoria, provável espécie-irmã dessa última. As áreas e densidades dos melanóforos são significativamente menores nas espécies troglóbias. Avaliando a resposta in vitro dessas células à adrenalina, acetilcolina e MCH, observamos uma resposta reduzida em ambos os troglóbios à adrenalina. A mesma tendência foi observado com o MCH, mas não estatisticamente. Nenhuma resposta à acetilcolina foi detectada três. Contrariamente às expectativas, embora a regressão ocular em P. spelaea seja bem menor do que em P. kronei, a regressão na pigmentação foi mais acentuada. Múltiplos mecanismos de regressão, mostrando um mosaico de características em peixes troglóbios, são discutidos aqui.

Leucism in South American lungfishes Lepidosiren paradoxa Fitzinger, 1837 (Osteichthyes, Dipnoi, Lepidosirenidae) from Argentina

The present study reports a case of leucism in South American Lungfish Lepidosiren paradoxa captured in Corrientes, Argentina. It was observed a change in cutaneous pigmentation, and it was concluded that it was leucism and not albinism, since there was a decrease of tegumentary melanin pigment and normal pigmentation in the retina.

Leucism in South American lungfishes Lepidosiren paradoxa Fitzinger, 1837 (Osteichthyes, Dipnoi, Lepidosirenidae) from Argentina

The present study reports a case of leucism in South American Lungfish Lepidosiren paradoxa captured in Corrientes, Argentina. It was observed a change in cutaneous pigmentation, and it was concluded that it was leucism and not albinism, since there was a decrease of tegumentary melanin pigment and normal pigmentation in the retina.(AU)

Regression of dark color in subterranean fishes involves multiple mechanisms: response to hormones and neurotransmitters

Organisms with source-populations restricted to the subterranean biotope (troglobites) are excellent models for comparative evolutionary studies, due to their specialization to permanent absence of light. Eye and dark pigment regression are characteristics of most troglobites. In spite of the advance in knowledge on the mechanisms behind eye regression in cave fishes, very little is known about pigmentation changes. Studies were focused on three species of the genus Pimelodella. Exemplars of the troglobitic P. spelaea and P. kronei were compared with the epigean (surface) P. transitoria, putative sister-species of the latter. Melanophore areas and densities are significantly lower in the troglobitic species. Evaluating the in vitro response of these cells to adrenaline, acetylcholine and MCH, we observed a reduced response in both troglobites to adrenaline. The same trend was observed with MCH, but not statistically significant. No response to acetilcholine was detected in all the three. Contrary to expectations, even though eye-regression in P. spelaea was much lower than in P. kronei, pigmentation regression was more advanced. Multiple mechanisms of loss showing a mosaic of traits in troglobitic fishes are discussed here.(AU)

Organismos com populações-fonte restritas ao biótopo subterrâneo (troglóbios) são excelentes modelos para estudos evolutivos comparativos, devido à especialização resultante do isolamento sob um regime seletivo particular, com ênfase na permanente falta de luz. A regressão do olho e da pigmentação são características dos troglobites. Apesar do avanço do conhecimento sobre os mecanismos subjacentes à regressão ocular em peixes de caverna, pouco se sabe sobre mudanças de pigmentação. Os estudos foram focados em três espécies do gênero Pimelodella. Exemplares das espécies troglóbias P. spelaea e P. kronei foram comparados com a epígea P. transitoria, provável espécie-irmã dessa última. As áreas e densidades dos melanóforos são significativamente menores nas espécies troglóbias. Avaliando a resposta in vitro dessas células à adrenalina, acetilcolina e MCH, observamos uma resposta reduzida em ambos os troglóbios à adrenalina. A mesma tendência foi observado com o MCH, mas não estatisticamente. Nenhuma resposta à acetilcolina foi detectada três. Contrariamente às expectativas, embora a regressão ocular em P. spelaea seja bem menor do que em P. kronei, a regressão na pigmentação foi mais acentuada. Múltiplos mecanismos de regressão, mostrando um mosaico de características em peixes troglóbios, são discutidos aqui.(AU)

Melanin bleaching with potassium permanganate for melanocytic lesions diagnosis in veterinary medicine / Despigmentação de melanócitos com permanganato de potássio para diagnóstico de lesões melanocíticas na medicina veterinária

The aim of this study was to microscopically re-evaluate the melanocytic lesions diagnoses established by the Animal Pathology Laboratory of the Federal University of Uberlândia, in the state of Minas Gerais, Brazil, over a period of eleven years; in addition, to perform a comparative analysis between the conventional histopathological (CH) method and the use of the melanin bleaching (MB) technique with potassium permanganate, sulfuric acid, and oxalic acid solutions. The results of the MB method presented a disagreement in 24.32% of the diagnosis previously by CH, with low agreement (61.0%) and low Kappa coefficient (0.2267). Melanoma was the most frequent lesion, more frequent in elderly and non-breed female dogs. The most frequent melanoma location was in the cutaneous tissue. The presence or absence of a pagetoid spread in cutaneous samples, distribution of melanin, pattern of cell layout, cell morphology, degree of cellular atypia, and the number of mitoses verified after MB were the most important criteria to confirm the diagnosis of malignancy or benignity of the lesions. Evaluating pathologists considered MB to be essential for the majority of diagnoses and an efficient complementary method for the diagnosis of melanocytic lesions, even in cases with a moderate degree of pigmentation.(AU)

Este estudo objetivou reavaliar microscopicamente os diagnósticos de lesões melanocíticas estabelecidos pelo setor de Patologia Animal da Universidade Federal de Uberlândia, em um período de 11 anos, e, com base nesse levantamento, realizar uma análise comparativa entre o método histopatológico convencional (HC) e o método de despigmentação de melanócitos (DM) com permanganato de potássio, ácido sulfúrico e ácido oxálico. A DM revelou discordância em 24,32% dos diagnósticos previamente estabelecidos por HC, apresentando baixa concordância (61,0%) e baixo valor de coeficiente Kappa (0,2267). A alteração mais frequente foi o melanoma, com maior ocorrência em cadelas idosas sem raça definida (SRD). A localização mais frequente dos melanomas foi cutânea. A presença ou ausência de disseminação pagetoide nos casos cutâneos, a forma de distribuição da melanina, o padrão de disposição das células, a morfologia celular, o grau de atipia celular e a quantidade de mitoses verificada após a despigmentação foram critérios de elevada importância para firmar o diagnóstico quanto à malignidade ou benignidade da lesão. A despigmentação foi considerada pelos patologistas avaliadores como essencial para o diagnóstico na maioria dos casos, o que leva a concluir que ela constitui um método complementar eficiente no diagnóstico das lesões melanocíticas, mesmo em casos com grau moderado de pigmentação.(AU)

Melanin bleaching with potassium permanganate for melanocytic lesions diagnosis in veterinary medicine / Despigmentação de melanócitos com permanganato de potássio para diagnóstico de lesões melanocíticas na medicina veterinária

The aim of this study was to microscopically re-evaluate the melanocytic lesions diagnoses established by the Animal Pathology Laboratory of the Federal University of Uberlândia, in the state of Minas Gerais, Brazil, over a period of eleven years; in addition, to perform a comparative analysis between the conventional histopathological (CH) method and the use of the melanin bleaching (MB) technique with potassium permanganate, sulfuric acid, and oxalic acid solutions. The results of the MB method presented a disagreement in 24.32% of the diagnosis previously by CH, with low agreement (61.0%) and low Kappa coefficient (0.2267). Melanoma was the most frequent lesion, more frequent in elderly and non-breed female dogs. The most frequent melanoma location was in the cutaneous tissue. The presence or absence of a pagetoid spread in cutaneous samples, distribution of melanin, pattern of cell layout, cell morphology, degree of cellular atypia, and the number of mitoses verified after MB were the most important criteria to confirm the diagnosis of malignancy or benignity of the lesions. Evaluating pathologists considered MB to be essential for the majority of diagnoses and an efficient complementary method for the diagnosis of melanocytic lesions, even in cases with a moderate degree of pigmentation.(AU)

Este estudo objetivou reavaliar microscopicamente os diagnósticos de lesões melanocíticas estabelecidos pelo setor de Patologia Animal da Universidade Federal de Uberlândia, em um período de 11 anos, e, com base nesse levantamento, realizar uma análise comparativa entre o método histopatológico convencional (HC) e o método de despigmentação de melanócitos (DM) com permanganato de potássio, ácido sulfúrico e ácido oxálico. A DM revelou discordância em 24,32% dos diagnósticos previamente estabelecidos por HC, apresentando baixa concordância (61,0%) e baixo valor de coeficiente Kappa (0,2267). A alteração mais frequente foi o melanoma, com maior ocorrência em cadelas idosas sem raça definida (SRD). A localização mais frequente dos melanomas foi cutânea. A presença ou ausência de disseminação pagetoide nos casos cutâneos, a forma de distribuição da melanina, o padrão de disposição das células, a morfologia celular, o grau de atipia celular e a quantidade de mitoses verificada após a despigmentação foram critérios de elevada importância para firmar o diagnóstico quanto à malignidade ou benignidade da lesão. A despigmentação foi considerada pelos patologistas avaliadores como essencial para o diagnóstico na maioria dos casos, o que leva a concluir que ela constitui um método complementar eficiente no diagnóstico das lesões melanocíticas, mesmo em casos com grau moderado de pigmentação.(AU)

Identification and characterisation of alternative splice variants of HOXB9 and their correlation with melanogenesis in the black-boned chicken

Homeobox B9 (HOXB9) gene has been demonstrated to be associated with melanogenesis in chicken plumage by high-throughput RNA sequencing. In this study, we cloned and characterised HOXB9 in black-boned chickens. Two alternative splice variants (HOXB9-1 and HOXB9-2) were identified in chicken feather bulbs. Expression analysis of HOXB9 in 11 different chicken tissues by RT-PCR indicated that the two transcripts were only expressed in the kidney, abdominal fat, feather bulbs, skin, and small intestine. No HOXB9-1 or HOXB9-2 transcripts were detected in the breast muscle or the ovary. The two HOXB9 variants were expressed at significantly different levels in black feather bulbs and white feather bulbs (p<0.01), and in black skin compared with white skin (p<0.01). The results indicate that HOXB9-1 and HOXB9-2 may be involved in melanin formation in the plumage and skin. The expression of HOXB9-2 was higher in white than in black muscles (p<0.05), HOXB9-2 may play a role in muscle melanogenesis. Our results suggest that HOXB9, which is partially regulated by alternative splicing, may be involved in the process of melanogenesis in the black-boned chicken.(AU)

Identification and characterisation of alternative splice variants of HOXB9 and their correlation with melanogenesis in the black-boned chicken

Homeobox B9 (HOXB9) gene has been demonstrated to be associated with melanogenesis in chicken plumage by high-throughput RNA sequencing. In this study, we cloned and characterised HOXB9 in black-boned chickens. Two alternative splice variants (HOXB9-1 and HOXB9-2) were identified in chicken feather bulbs. Expression analysis of HOXB9 in 11 different chicken tissues by RT-PCR indicated that the two transcripts were only expressed in the kidney, abdominal fat, feather bulbs, skin, and small intestine. No HOXB9-1 or HOXB9-2 transcripts were detected in the breast muscle or the ovary. The two HOXB9 variants were expressed at significantly different levels in black feather bulbs and white feather bulbs (p<0.01), and in black skin compared with white skin (p<0.01). The results indicate that HOXB9-1 and HOXB9-2 may be involved in melanin formation in the plumage and skin. The expression of HOXB9-2 was higher in white than in black muscles (p<0.05), HOXB9-2 may play a role in muscle melanogenesis. Our results suggest that HOXB9, which is partially regulated by alternative splicing, may be involved in the process of melanogenesis in the black-boned chicken.