RESUMO A qualidade das raízes de batata-doce é influenciada por fatores que antecedem a colheita. Assim, objetivou-se na execução deste trabalho a correta determinação do ponto de colheita e o estudo da qualidade pós-colheita de duas cultivares de batata-doce colhidas em diferentes idades de colheita. O experimento foi realizado nas dependências da Universidade Federal de Roraima. As plantas foram cultivadas de abril a agosto, durante o período chuvoso de 2020. A colheita foi realizada aos 80, 95, 110, 125 e 140 dias após o plantio (DAP). As raízes foram higienizadas e em seguida foram avaliadas as características físico-químicas da polpa e casca. Os sólidos solúveis, acidez titulável e relação SS/AT foram observados em maior quantidade na cultivar BD-02. A luminosidade e croma da casca das raízes tuberosas de batata-doce foram mais intensas na cultivar BD-01 e o inverso foi observado na caracterização da polpa da cultivar BD-01. Aos 110 dias após plantio (DAP) observou-se os maiores teores de açúcares redutores e croma da casca; menores valores de croma da polpa e °H da casca. Dessa forma, segundo os resultados acima apresentados, especialmente em função do metabolismo dos carboidratos e a observação da produtividade e o acúmulo de matéria seca, a cultivar BD-02, colhida aos 110 DAP, apresentou as melhores características pós-colheita nas condições experimentais aqui apresentadas.

ABSTRACT The quality of sweet potato roots is influenced by factors which precede harvest. Thus, the aim of this study was to correctly determine the harvest point and study the postharvest quality of two sweet potato cultivars harvested at different ages. The experiment was carried out at Universidade Federal de Roraima. The plants were grown from April to August, during rainy season, 2020. The harvest was carried out at 80, 95, 110, 125 and 140 days after planting (DAP). The tuberous roots were cleaned and the physicochemical traits of the pulp and peel were evaluated. Soluble solids, titratable acidity and SS/AT ratio were observed in greater quantity in the cultivar BD-02. The luminosity and chroma of the peel of the sweet potato roots were more intense in the cultivar BD-01 and the opposite was observed when characterizing the pulp of this cultivar. At 110 DAP, we verified the highest levels of reducing sugars and chroma of the peel, as well as lower values for the chroma of the pulp and °H of the peel. Thus, according to the results presented above, especially in relation to carbohydrate metabolism, productivity and dry matter accumulation, the cultivar BD-02, harvested at 110 DAP, showed the best postharvest traits under the experimental conditions presented in this study.

RESUMO Apesar da relevância do enxofre (S) para o desenvolvimento das plantas, estudos sobre sua disponibilidade no solo são restritos à algumas culturas e regiões do Brasil. Assim, objetivou-se com este trabalho comparar extratores para avaliar a disponibilidade de S e estabelecer níveis críticos em solos do estado do Ceará. Em laboratório foi extraído o S disponível de 23 solos (0 - 0,20 m), empregando-se dois extratores: soluções de Ca(H2PO4)2, 500 mg L-1 de P, em H2O (MCP) e NH4OAc em HOAc (AMA). Em experimento instalado em casa de vegetação foi usado, como planta indicadora, o sorgo forrageiro (Sorghum vulgari Pers.), cultivar EA116, em dois cultivos sucessivos. O delineamento experimental foi inteiramente casualizado, em esquema fatorial (23 x 2), com três repetições. Os termos do fatorial corresponderam aos solos e doses de S (0 e 80 mg por unidade experimental). O MCP apresentou maior eficiência de extração de S disponível que o AMA, embora o teor de S obtido por ambos tenha apresentado correlação significativa (r = 0,96). O S disponível por MCP apresentou melhor correlação com incremento de produção e S absorvido, sugerindo ser o mais indicado. Os níveis críticos de S foram de 3,90 e 3,40 mg dm-3 para MCP e AMA, respectivamente.

ABSTRACT Despite the relevance of sulphur (S) to plant development, studies in Brazil on its availability in the soil are restricted to a few crops and regions. The aim of this study was to compare extractants for assessing the availability of S, and establish critical levels for soils in the state of Ceará. In the laboratory, available S was extracted from 23 soils (0 - 0.20 m), using two extractants: a solution of Ca(H2PO4)2, 500 mg L-1 P in H2O (MCP) and NH4OAc in HOAc (AMA). In an experiment set up in a greenhouse, forage sorghum ‘EA116’ (Sorghum vulgari Pers.) was used as an indicator plant in two successive crops. A completely randomised experimental design was employed, in a 23 x 2 factorial scheme with three replications, where the factors corresponded to the soils and to the doses of S (0 and 80 mg per experimental unit). The MCP was more efficient in extracting available S than was the AMA, although the S content obtained by both did show a significant correlation (r = 0.96). The available S using MCP showed a better correlation, with an increase in production and in absorbed S, suggesting MCP to be the most suitable extractant. The critical levels for S were 3.90 and 3.40 mg dm-3 for MCP and AMA, respectively.

ABSTRACT Although there are already available pineapple cultivars resistant to fusariosis, Brazilian production is based on the cultivar Pérola, susceptible to fusariosis. Studies with these resistant cultivars should prioritize the fulfillment of nutritional requirements, so that they express their productive potential and become viable options for producers. The objective of this study was to study the effects of foliar fertilizer compositions on the growth and yield of five micropropagated pineapple cultivars. The study was started in a greenhouse and at 210 days after transplanting, the seedlings were transferred to field conditions. The experimental design was in randomized blocks, in subdivided plots with three factors and four replications. The combination of the five pineapple cultivars (BRS Ajubá, IAC Fantástico, BRS Imperial, Pérola and BRS Vitória) and three leaf fertilizer compositions (NK, NPK and NPK + micronutrients) were randomized in plots and six evaluation periods consisted of subplots. Agronomic attributes were analyzed at the time of evaluation. The results obtained were subjected to analysis of variance by the F test. The Scott-Knott test was used for comparisons between cultivars and fertilization, and regression for the seasons, using the SISVAR program. Regardless of fertilization, cv. IAC Fantástico stood out in the majority of the evaluated characters, being superior to cv. Pérola, considered standard. The NK formula shows to be the best option for use as leaf fertilizer in the pineapple crop. The cultivar IAC Fantástico has good vegetative and productive characteristics, having the potential to be a viable option for cultivation in the state of Roraima.

RESUMO Embora já se disponha de cultivares de abacaxizeiro resistentes à fusariose, a produção brasileira é baseada na cultivar Pérola, susceptível à fusariose. Estudos com essas cultivares resistentes devem priorizar o atendimento das exigências nutricionais, para que elas expressem seu potencial produtivo e se tornem opções viáveis para os produtores. Objetivou-se estudar os efeitos de composições de adubo foliar no crescimento e produção de cinco cultivares de abacaxizeiro micropropagadas. O estudo foi iniciado em casa de vegetação e aos 210 dias após o transplantio, as mudas foram transferidas para o campo. O delineamento experimental foi em blocos casualizados, em parcelas subdivididas com três fatores e quatro repetições. A combinação das cinco cultivares de abacaxizeiro (BRS Ajubá, IAC Fantástico, BRS Imperial, Pérola e BRS Vitória) e três composições de adubo foliar (NK, NPK e NPK + micronutrientes) foram aleatorizadas nas parcelas e seis épocas de avaliação, nas subparcelas. Atributos agronômicos foram analisados nas épocas de avaliação. Os resultados obtidos foram submetidos à análise de variância pelo teste F. Foi empregado o teste de Scott-Knott para as comparações entre cultivares e adubação, e de regressão para as épocas, empregando-se o programa SISVAR. Independente da adubação, a cv. IAC Fantástico se destacou na maioria dos caracteres avaliados, sendo superior a cv. Pérola, considerada padrão. A fórmula NK mostra ser a melhor opção para utilização como adubo foliar na cultura do abacaxizeiro. A cultivar IAC Fantástico apresenta boas características vegetativas e produtivas, tendo potencial para ser uma opção viável para cultivo no estado de Roraima.

The ultimate goal of periodontal therapy is to repair the damaged periodontal supporting tissues, permitting regeneration of the periodontal ligament. However, the cell response, the supportive matrix and the bioactive molecules use have not yet been well established. Bone marrow mononuclear cells were extracted from rat femurs and tibiae and cultured on a cross-linked collagen membrane, bone graft, or molar tooth to compare cell attachment and early proliferation on these materials. Cell attachment was quantified by light microscopy at 24, 48 and 72h, and cell proliferation was observed under a SEM after 72h. After 24h, the number of cells on bone graft was similar to that of the control and more than twice compared to collagen membrane (q=7.473 p<0.001) and 1.75 times greater than with tooth cementum (q=5.613 p<0.01). However, the number of cells close to bone graft decreased in the second day compared to the control. SEM examination revealed a significant decrease in the number of cells that attached and proliferated on tooth and bone graft when compared with membrane. The results showed that bone marrow mesenchymal cells offer great potential for colonize a collagen membrane.

El objetivo último de la terapia periodontal es reparar el daño tejidos periodontales de soporte, permitiendo la regeneración del ligamento periodontal. Sin embargo, la respuesta de la célula, la matriz de apoyo y las moléculas bioactivas aún no han sido bien establecidas. Células mononucleares de la médula ósea se extrajeron del fémur y fibula de rata, y fueron cultivadas sobre un reticulado de membrana de colágeno, de injerto de hueso o de un diente molar para comparar la adhesión celular y la proliferación temprana sobre estos materiales. La adhesión celular fue cuantificada por microscopía de luz a las 24, 48 y 72h, y la proliferación celular fue observada bajo MEB después de 72h. Después de 24 horas, el número de células sobre el injerto de hueso fue similar a la del control y más del doble en comparación con la membrana de colágeno (q=7,473 p<0,001) y 1,75 veces mayor que con el cemento dental (q=5,613 p<0,01). Sin embargo, el número de células cerca del injerto óseo disminuyó el segundo día en comparación con el control. El examen al MEB reveló una disminución significativa en el número de células que se unen y proliferan sobre los dientes y el injerto óseo en comparación con la membrana. Los resultados mostraron que las células mesenquimales de la médula ósea tienen un gran potencial para colonizar la membrana de colágeno.

Although the predilection for Toxoplasma gondii to form cysts in the nervous system and skeletal and heart muscles has been described for more than fifty years, skeletal muscle cells (SkMCs) have not been explored as a host cell type to study the Toxoplasma-host cell interaction and investigate the intracellular development of the parasite. Morphological aspects of the initial events in the Toxoplasma-SkMC interaction were analysed and suggest that there are different processes of protozoan adhesion and invasion and of the subsequent fate of the parasite inside the parasitophorous vacuole (PV). Using scanning electron microscopy,Toxoplasma tachyzoites from the mouse-virulent RH strain were found to be attached to SkMCs by the anterior or posterior region of the body, with or without expansion of the SkMC membrane. This suggests that different types of parasite internalization occurred. Asynchronous multiplication and differentiation of T. gondii were observed. Importantly, intracellular parasites were seen to display high amounts of amylopectin granules in their cytoplasm, indicating that tachyzoites of the RH strain were able to differentiate spontaneously into bradyzoites in SkMCs. This stage conversion occurred in approximately 3% of the PVs. This is particularly intriguing as tachyzoites of virulent Toxoplasma strains are not thought to be prone to cyst formation. We discuss whether biological differences in host cells are crucial to Toxoplasma stage conversion and suggest that important questions concerning the host cell type and its relevance in Toxoplasma differentiation are still unanswered.

Infection by the protozoan parasite Toxoplasma gondii is widely prevalent in humans and animals. To prevent human infection, all meat should be well cooked before consumption, since the parasite is present in skeletal muscle. In this context, the use of skeletal muscle cells (SkMCs) as a cellular model opens up new approaches to investigate T. gondii-host cell interactions. Immunofluorescent detection of proteins that are stage-specific for bradyzoites indicated that complete cystogenesis of T. gondii in in vitro cultures of SkMCs occurs after 96 h of infection. Ultrastructural analysis showed that, after 48 h of interaction, there were alterations on the parasitophorous vacuole membrane, including greater thickness and increased electron density at the inner face of the membrane. The present study demonstrates the potential use of primary cultures of SkMCs to evaluate different molecular aspects of T. gondii invasion and cystogenesis and presents a promising in vitro model for the screening of drug activities toward tissue cysts and bradyzoites.

Ultrathin sections of tissue cysts isolated from the brain of Toxoplasma gondii infected mice were submitted to two different methodologies derived from the periodic acid - Schiff's reagent (PAS) technique. The use of osmium tetroxide vapor as a developing agent of the aldehyde oxidation to reveal polysaccharides with periodic acid resulted in positive reaction in amylopectin granules in bradyzoites, as well as in the wall and matrix of the cysts, with excellent increment of the ultrastructural morphology. This technique can be used for study of T. gondii-host cell intracellular cycle, the differentiation tachyzoite-bradyzoite, and also for the formation of cysts into the host cells.

Toxoplasma gondii invades and proliferates in human umbilical vein endothelial cells where it resides in a parasitophorous vacuole. In order to analyze which components of the endothelial cell plasma membrane are internalized and become part of the parasitophorous vacuole membrane, the culture of endothelial cells was labeled with cationized ferritin or UEA I lectin or anti Class I human leukocytte antigen (HLA) before or after infection with T. gondii. The results showed no cationized ferritin and UEA I lectin in any parasitophorous vacuole membrane, however, the Class I HLA molecule labeling was observed in some endocytic vacuoles containing parasite until 1 h of interaction with T. gondii. After 24 h parasite-host cell interaction, the labeling was absent on the vacuolar membrane, but presents only in small vesicles near parasitophorous vacuole. These results suggest the anionic site and fucose residues are excluded at the time of parasitophorous vacuole formation while Class I HLA molecules are present only on a minority of Toxoplasma-containig vacuoles.