Determination of the relationship among cell proliferation, metabolic activity and stage of pregnancy by AgNORs as markers in bovine placenta / Determinación de la relación entre la proliferación celular, la actividad metabólica y la etapa de preñez por los AgNOR como marcadores en la placenta bovina

SUMMARY: Nucleolus Organizer Regions (NORs) are defined as nucleolar components containing argyrophilic proteins selectively stained by silver methods (AgNORs). Several investigations have shown the AgNOR quantity and area represent a valuable parameter of cell kinetics, since they reflect the level of activity and cellular proliferation. This article addresses an evaluation of the functional activity and relation between days of pregnancy and proliferative capacity of trophoblastic mononucleate and binucleate cells from bovine placentomes. Both the number and size of AgNORs were determined in different phases of gestation by silver nitrate staining in conventional histological slides. The results showed a significant increase (from 1 to 12 AgNORs) in the number of AgNORS per trophoblastic mononucleate cell in the 3rd trimester, with predominance of 4-6 AgNORs/cell. In the 1st and 2nd trimesters, the number ranged between 1 and 9 AgNORs/cell, with predominance of 1-3 AgNORs. No significant differences were observed between the 2nd and 3rd trimesters, but in the first, in binucleate cells (19-27 and 10-18 AgNORs/cell, respectively) - this number was higher than the one registered in trophoblastic mononucleate cells in the same period. Thus, AgNORs can be used as markers of the proliferative placental cell cycle and established a relation between number of AgNORs and days of gestation. This relation can be used for diagnoses and prognoses of several placental pathologies, including pregnancy losses from manipulated embryos.

RESUMEN: Las Regiones Organizadoras de Nucléolos (NOR) se definen como componentes nucleolares que contienen proteínas argirofílicas teñidas selectivamente por métodos de plata (AgNOR). Varias investigaciones han demostrado que la cantidad y el área de AgNOR representan un parámetro importante de la cinética celular, ya que reflejan el nivel de actividad y proliferación celular. Este trabajo analiza la actividad funcional y la relación entre los días de preñez y la capacidad proliferativa de las células trofoblásticas mononucleadas y binucleadas de placentomas bovinos. Tanto el número como el tamaño de los AgNOR se determinaron en diferentes fases de la gestación mediante tinción con nitrato de plata en portaobjetos histológicos convencionales. Los resultados mostraron un aumento significativo (de 1 a 12 AgNOR) en el número de AgNORS por célula mononucleada trofoblástica en el tercer trimestre, con predominio de 4-6 AgNOR / célula. En el primer y segundo trimestre, el número osciló entre 1 y 9 AgNOR / célula, con predominio de 1-3 AgNOR. No se observaron diferencias significativas entre el 2do y 3er trimester; en el primer trimestre, en células binucleadas (19-27 y 10-18 AgNORs / célula, respectivamente) - este número fue superior a la cantidad registrada en células mononucleadas trofoblásticas en el mismo período. Por tanto, los AgNOR se pueden utilizar como marcadores del ciclo celular placentario proliferativo y se establece una relación entre el número de AgNOR y los días de gestación. Esta relación puede ser útil en el diagnóstico y pronóstico de varias patologías placentarias, incluidas las pérdidas de preñeces de embriones manipulados.

Quantitative analysis of nucleolar chromatin distribution in the complex convoluted nucleoli of Didinium nasutum (Ciliophora)

We have earlier shown that the typical Didinium nasutum nucleolus is a complex convoluted branched domain, comprising a dense fibrillar component located at the periphery of the nucleolus and a granular component located in the central part. Here our main interest was to study quantitatively the spatial distribution of nucleolar chromatin structures in these convoluted nucleoli. There are no "classical" fibrillar centers in D.nasutum nucleoli. The spatial distribution of nucleolar chromatin bodies, which play the role of nucleolar organizers in the macronucleus of D.nasutum, was studied using 3D reconstructions based on serial ultrathin sections. The relative number of nucleolar chromatin bodies was determined in macronuclei of recently fed, starved D.nasutum cells and in resting cysts. This parameter is shown to correlate with the activity of the nucleolus. However, the relative number of nucleolar chromatin bodies in different regions of the same convoluted nucleolus is approximately the same. This finding suggests equal activity in different parts of the nucleolar domain and indicates the existence of some molecular mechanism enabling it to synchronize this activity in D. nasutum nucleoli. Our data show that D. nasutum nucleoli display bipartite structure. All nucleolar chromatin bodies are shown to be located outside of nucleoli, at the periphery of the fibrillar component.

Cytogenetic characterization of Crenicichla (Pisces, Perciformes, Cichlidae) of the Iguaçu River

Three populations of the genus Crenicichla, namely Crenicichla iguassuensis, Crenicichla sp 1 and Crenicichla sp 2, from the Iguaçu River, were analyzed cytogenetically, and their nucleolus organizer regions, constitutive heterochromatin distribution and chromomycin A3 markings were studied. Karyotype analyses showed a diploid number of 48 chromosomes, made up of 2 metacentric pairs, 2 submetacentric pairs, 7 subtelocentric pairs, and 13 acrocentric pairs for the three Crenicichla species and no sexual chromosome differentiation. Nucleolus organizer regions showed strong interstitial marking on the first chromosome pair, coincident with a constriction presented by Giemsa and positive marking by chromomycin. Although constitutive heterochromatin patterns were also similar, with pericentromeric markings, small differences in the three species could be observed. Crenicichla sp 2 presented some chromosomes with bitelomeric markings absent in Crenicichla iguassuensis and Crenicichla sp 1.

Diagnostic value of silver nitrate staining for nucleolar organizer regions in selected head and neck tumors.

BACKGROUND: The present study is aimed to assess the usefulness of silver nitrate staining of nucleolar organizer regions (NORs) as a quantitative criterion for the diagnosis of selected head and neck tumors. MATERIALS AND METHODS: The silver nitrate staining technique was used on 195 paraffin blocks collected from 85 patients. The samples consisted of 21 squamous cell carcinoma (SCC) of larynx, 28 SCC of oral mucosa and 36 samples of most common salivary gland tumors. Mann-Whitney U-Test was used for data analysis. RESULTS: A significant difference was seen in the number of AgNOR dots between oral and laryngeal SCC with surrounding dysplastic and normal tissues (P < 0.001) and also between mucoepidermoid carcinoma and adenoid cystic carcinoma with pleomorphic adenoma and normal salivary gland tissue (P < 0.001). CONCLUSION: The silver nitrate staining for NORs is a useful method for aiding the diagnosis of malignant and dysplastic mucosal lesions and also malignant and benign salivary gland tumors.

Nucleolar organizer regions (NORs) in simple and proliferating trichilemmal cysts (pilar cysts and pilar tumors).

Simple trichilemmal cysts or pilar cysts and pilar tumors are relatively rare entities often under-reported by pathologists. The pilar cysts are thought to proliferate and progress to pilar tumors. These pilar tumors can further undergo malignant change. We analyzed 25 pilar cysts and eight pilar tumors, including three with atypia and one malignant pilar tumor, with a view to study the above progression and assess the degree of cell proliferation using the Nucleolar Organizer Regions (AgNORs). There was a progressive increase in the AgNOR count from one dot per nucleus in pilar cysts to 1.5-2 in benign pilar tumors. AgNORs in pilar tumors with atypia (2.8) was more than the benign pilar tumors but were definitely less than the malignant pilar tumors (3.5). The malignant pilar tumor showed bizarre AgNORs and cells with as many as eight to nine AgNORs. Thus AgNOR counts suggested that there is a progressive increase in the degree of cell proliferation and thereby the AgNOR staining from pilar cysts to pilar tumors. This AgNOR staining could also be used to assess the cell proliferation in case of pilar tumors with atypia where it is difficult to rule out malignancy.

AgNORs in squamous cell carcinoma of head and neck.

The number of AgNORs per nucleus correlates with cellular proliferation and independently with malignant change. AgNOR number was studied in 200 cases of squamous cell carcinoma of head and neck, the count increased with increasing grade and the size became smaller and irregular with increasing grade of carcinoma. This study seems to suggest that this method has utility in grading of squamous cell carcinoma of head and neck.

Análise quantitativa das AgNORs no carcinoma adenóide cístico intra-oral através da técnica de dupla marcação PCNA/AgNOR / PCNA/AgNOR double staining technique in adenoid cystic carcinoma

A análise quantitativa das AgNORs e imunomarcação para o PCNA têm sido empregadas de forma independente na avaliação da proliferação celular de vários tumores, e, em muitos casos, têm mostrado correlação positiva. Entretanto poucos trabalhos têm avaliado, em um mesmo corte histológico, a relação entre PCNA e AgNOR. O objetivo deste trabalho foi otimizar a técnica de dupla marcação com a finalidade de se estudar simultaneamente a correlação entre PCNA e AgNOR no carcinoma adenóide cístico (CAC) de glândulas salivares menores. Foram selecionados 16 casos de CAC classificados de acordo com o subtipo histológico. A análise quantitativa das AgNORs foi feita por meio de análise de imagens. As AgNORs foram contadas em cem núcleos PCNA positivos e em cem núcleos PCNA negativos. O número médio de AgNOR nos núcleos PCNA positivos foi 2,14 ñ 0,77, e, nos núcleos PCNA negativos, 1,97 ñ 0,79, entretanto esta diferença não se mostrou estatisticamente significante (p = 0,2537). Nosso trabalho não mostrou correlação entre o número de AgNOR e a imunomarcação para o PCNA em CAC quando estes marcadores foram demonstrados sinultaneamente através da dupla marcação. Quanto à técnica, o uso do microondas melhorou a coloração da AgNOR, permitindo uma redução no tempo de incubação com a solução de prata e uma melhor individualização das AgNORs, o que facilitou os procedimentos de contagem

DNA synthesis and nucleolar organizer regions circadian rhythm in mouse regenerating liver hepatocytes

DNA synthesis and Nucleolar Organizer Regions (NORs) were studied in C3HS inbred mice standardized for periodicity analysis. Immunohistochemical detection of Bromodeoxyuridine (BrdU) incorporated into DNA with a monoclonal antibody and silver staining of NORs (AgNORs) were assessed by means of a digital image analysis system in histological sections of regenerating liver. Tissue samples were obtained at different times after hepatectomy along a circadian span. The results showed a strong correlation of values between DNA synthesis (BrdU labelling index) and AgNOR numbers, with higher counts during the activity period of animals at 00:00/38 and 04:00/42 hours Time of Day/Hours Post-Hepatectomy (TD/HPH), being the differences with other time points highly significant. Our observations demonstrate the existence of a strong correlation of DNA synthesis measured by BrdU incorporation and AgNOR numbers with a defined circadian rhythm in mouse regenerating hepatocytes.