Universidade Federal de Viçosa

About: Universidade Federal de Viçosa is a education organization based out in Viçosa, Brazil. It is known for research contribution in the topics: Population & Biology. The organization has 16012 authors who have published 26711 publications receiving 353416 citations.

Interplay between insulin signaling, juvenile hormone, and vitellogenin regulates maternal effects on polyphenism in ants.

Abstract: Polyphenism is the phenomenon in which alternative phenotypes are produced by a single genotype in response to environmental cues An extreme case is found in social insects, in which reproductive queens and sterile workers that greatly differ in morphology and behavior can arise from a single genotype Experimental evidence for maternal effects on caste determination, the differential larval development toward the queen or worker caste, was recently documented in Pogonomyrmex seed harvester ants, in which only colonies with a hibernated queen produce new queens However, the proximate mechanisms behind these intergenerational effects have remained elusive We used a combination of artificial hibernation, hormonal treatments, gene expression analyses, hormone measurements, and vitellogenin quantification to investigate how the combined effect of environmental cues and hormonal signaling affects the process of caste determination in Pogonomyrmex rugosus The results show that the interplay between insulin signaling, juvenile hormone, and vitellogenin regulates maternal effects on the production of alternative phenotypes and set vitellogenin as a likely key player in the intergenerational transmission of information This study reveals how hibernation triggers the production of new queens in Pogonomyrmex ant colonies More generally, it provides important information on maternal effects by showing how environmental cues experienced by one generation can translate into phenotypic variation in the next generation

Attraction and oviposition of Tuta absoluta females in response to tomato leaf volatiles.

Abstract: The tomato leafminer Tuta absoluta (Lepidoptera: Gelechiidae) is a devastating pest of cultivated tomato Solanum lycopersicum throughout South and Central America and Europe We aimed to characterize the behavioral mechanisms and the chemical cues involved in host selection of T absoluta females by chemical analysis of tomato leaf volatiles, wind tunnel attraction assays, and oviposition bioassays Tomato leaf odor elicited in mated females upwind orientation flight followed by landing as well as egg-laying, demonstrating the essential role of plant volatiles in T absoluta host-finding behavior In wind tunnel and oviposition choice experiments, T absoluta females significantly preferred tomato S lycopersicum over wild tomato Solanum habrochaites, which is resistant to larval feeding This indicates that leaf volatiles provide information on the suitability of plants as larval hosts Mated females also discriminated three cultivars of S lycopersicum according to their volatile profiles Headspace collections from leaves of these three cultivars contained large amounts of β-phellandrene, followed by limonene, 2-carene, and (E)-β-caryophyllene, which together accounted for more than 70% of tomato foliage headspace Most leaf volatiles were released by all three cultivars, but they showed significant differences with respect to the presence of a few minor compounds and blend proportion This is an initial study of the volatile signatures that mediate attraction and oviposition of tomato leafminer T absoluta in response to its main host, tomato

Adição de ácidos orgânicos e húmicos em Latossolos e adsorção de fosfato

Abstract: A materia orgânica pode diminuir a adsorcao/precipitacao de fosfato (A/PP) pela liberacao de acidos orgânicos, que competem pelos sitios de adsorcao, ou pela formacao de compostos com o fosfato na solucao do solo e, ou, formacao de complexos com Al e Fe, reduzindo a A/PP. O objetivo deste trabalho foi avaliar a reducao na A/PP em Latossolos, pela adicao de acidos orgânicos: acido citrico (AC), oxalico (AO), salicilico (AS) - e de acidos humicos (AH). Foram utilizadas amostras de um Latossolo Vermelho textura muito argilosa - (LV) e um Latossolo Vermelho-Amarelo textura franco-argilo-arenosa - (LVA). Amostras de 2,5 cm3 de TFSA dos solos foram colocadas em erlenmeyer onde foram adicionados: fosforo (K2HPO4) e, ou, acidos orgânicos ou humicos, de acordo com a forma de aplicacao (fosfato antes, junto e depois da aplicacao do acido), nas doses da relacao molar acido orgânico/P variando de 0 a 2:1. As doses dos acidos humicos variaram de 0 a 89,28 mg cm-3, equivalendo a adubacao orgânica de 0 a 40 t ha-1 de material orgânico. O efeito dos acidos orgânicos/acidos humicos na reducao da A/PP nos dois solos seguiu a seguinte ordem: AC > AO > AH > AS. A forma de adicao dos acidos influenciou a A/PP em ambos os solos. No LV, a aplicacao de fosfato e acidos orgânicos ou acidos humicos juntos (FJA) causou a maior reducao na A/PP, indicando que deve ter ocorrido a ligacao entre fosfato e acidos. No LVA, a aplicacao de fosfato depois dos acidos orgânicos ou acidos humicos (FDA) causou a maior reducao na A/PP, indicando ter ocorrido bloqueio dos sitios de adsorcao pelos acidos.

Laser-Induced Graphene Electrochemical Immunosensors for Rapid and Label-Free Monitoring of Salmonella enterica in Chicken Broth

Abstract: Food-borne illnesses are a growing concern for the food industry and consumers, with millions of cases reported every year. Consequently, there is a critical need to develop rapid, sensitive, and inexpensive techniques for pathogen detection in order to mitigate this problem. However, current pathogen detection strategies mainly include time-consuming laboratory methods and highly trained personnel. Electrochemical in-field biosensors offer a rapid, low-cost alternative to laboratory techniques, but the electrodes used in these biosensors require expensive nanomaterials to increase their sensitivity, such as noble metals (e.g., platinum, gold) or carbon nanomaterials (e.g., carbon nanotubes, or graphene). Herein, we report the fabrication of a highly sensitive and label-free laser-induced graphene (LIG) electrode that is subsequently functionalized with antibodies to electrochemically quantify the food-borne pathogen Salmonella enterica serovar Typhimurium. The LIG electrodes were produced by laser induction on the polyimide film in ambient conditions and, hence, circumvent the need for high-temperature, vacuum environment, and metal seed catalysts commonly associated with graphene-based electrodes fabricated via chemical vapor deposition processes. After functionalization with Salmonella antibodies, the LIG biosensors were able to detect live Salmonella in chicken broth across a wide linear range (25 to 105 CFU mL-1) and with a low detection limit (13 ± 7 CFU mL-1; n = 3, mean ± standard deviation). These results were acquired with an average response time of 22 min without the need for sample preconcentration or redox labeling techniques. Moreover, these LIG immunosensors displayed high selectivity as demonstrated by nonsignificant response to other bacteria strains. These results demonstrate how LIG-based electrodes can be used for electrochemical immunosensing in general and, more specifically, could be used as a viable option for rapid and low-cost pathogen detection in food processing facilities before contaminated foods reach the consumer.