RESUMO
Drosophila melanogaster is undoubtedly one of the most useful model organisms in biology. Initially used in solidifying the principles of heredity, and establishing the basic concepts of population genetics and of the synthetic theory of evolution, it can currently offer scientists much more: the possibility of investigating a plethora of cellular and biological mechanisms, from development and function of the immune system to animal neurogenesis, tumorigenesis and beyond. Extensive resources are available for the community of Drosophila researchers worldwide, including an ever-growing number of mutant, transgenic and genomically-edited lines currently carried by stock centers in North America, Europe and Asia. Here, we provide evidence for the importance of stock centers in sustaining the substantial increase in the output of Drosophila research worldwide in recent decades. We also discuss the challenges that Brazilian Drosophila scientists face to keep their research projects internationally competitive, and argue that difficulties in importing fly lines from international stock centers have significantly stalled the progression of all Drosophila research areas in the country. Establishing a local stock center might be the first step towards building a strong local Drosophila community that will likely contribute to all areas of life sciences research.
RESUMO
Dorsal-ventral patterning of the Drosophila embryo depends on the NFκB superfamily transcription factor Dorsal (Dl). Toll receptor activation signals for degradation of the IκB inhibitor Cactus (Cact), leading to a ventral-to-dorsal nuclear Dl gradient. Cact is critical for Dl nuclear import, as it binds to and prevents Dl from entering the nuclei. Quantitative analysis of cact mutants revealed an additional Cact function to promote Dl nuclear translocation in ventral regions of the embryo. To investigate this dual Cact role, we developed a predictive model based on a reaction-diffusion regulatory network. This network distinguishes non-uniform Toll-dependent Dl nuclear import and Cact degradation, from the Toll-independent processes of Cact degradation and reversible nuclear-cytoplasmic Dl flow. In addition, it incorporates translational control of Cact levels by Dl. Our model successfully reproduces wild-type data and emulates the Dl nuclear gradient in mutant dl and cact allelic combinations. Our results indicate that the dual role of Cact depends on the dynamics of Dl-Cact trimers along the dorsal-ventral axis: In the absence of Toll activation, free Dl-Cact trimers retain Dl in the cytoplasm, limiting the flow of Dl into the nucleus; in ventral-lateral regions, Dl-Cact trimers are recruited by Toll activation into predominant signaling complexes and promote Dl nuclear translocation. Simulations suggest that the balance between Toll-dependent and Toll-independent processes are key to this dynamics and reproduce the full assortment of Cact effects. Considering the high evolutionary conservation of these pathways, our analysis should contribute to understanding NFκB/c-Rel activation in other contexts such as in the vertebrate immune system and disease.
Assuntos
Núcleo Celular/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila/metabolismo , Quinase I-kappa B/metabolismo , Modelos Biológicos , NF-kappa B/metabolismo , Fosfoproteínas/metabolismo , Animais , Transporte Proteico , Transdução de SinaisRESUMO
In a previous study, we found that the embryonic cuticle of Rhodnius prolixus is a chitin-based structure that helps the first instar nymph to hatch from the chorion. Here, we investigated how the reduction of transcripts induced by CHS dsRNA injection affects R. prolixus embryogenesis and eclosion. Deposition of chitin in the embryonic cuticle begins later at embryogenesis, around day 8, and ends approximately at day 15, when the insects are ready for eclosion. In R. prolixus, chitin deposition follows pari passu with the synthesis of the chitin synthase mRNA, indicating a regulation at the transcriptional level. The reduction of the chitin synthase gene transcripts by the injection of CHS dRNA prevented chitin deposition during embryonic cuticle formation, being lethal to hatching nymphs, which end up dying while stuck in the chorionic border trying to leave the chorion. The successful eclosion rates were reduced by 60% in animals treated with CHS dsRNA when compared to animals injected with a control (dsRNA no related gene or water). We found that the harmful effects on oviposition and eclosion are possibly due to changes in the structure of the embryonic cuticle, as observed by directly comparing the morphology of control and chitin-deficient embryonic cuticles under the transmission electron microscope. The lack of chitin and changes in its morphological characteristics appears to alter the embryonic cuticle physiology and functionality. Additionally, we observed that the effects of CHS dRNA treatment on R. prolixus females lasted up to 3 egg-laying cycles (â¼100 days), pointing to R. prolixus as a useful model for developmental studies.
Assuntos
Ninfa/genética , Ninfa/metabolismo , Oviposição/genética , Interferência de RNA , Rhodnius/embriologia , Rhodnius/genética , Animais , Quitina/metabolismo , Quitina Sintase/genética , Feminino , Oviposição/fisiologia , RNA Mensageiro , Rhodnius/metabolismoRESUMO
We developed a simple methodology for labeling sulfated glycosaminoglycans (GAGs) in adult Drosophila melanogaster and studied some aspects of the biosynthesis and metabolism of these polymers during development. Adult D. melanogaster flies were fed with Na(2)(35)SO(4) for 72 h. During this period, (35)S-sulfate was incorporated into males and females and used to synthesize (35)S-sulfate-heparan sulfate (HS) and (35)S-sulfate-chondroitin sulfate (CS). The incorporation of (35)S-sulfate into HS was higher when compared to CS. In a pulse-chase experiment, we observed that (35)S-sulfate incorporated into adult female was recovered in embryos and used for the synthesis of new (35)S-sulfate-GAGs after 2 h of embryonic development. The synthesis of CS was higher than that of HS, indicating a change in the metabolism of these glycans from adult to embryonic and larval stages. Analysis of the CS in embryonic and larval tissues revealed the occurrence of nonsulfated and 4-sulfated disaccharide units in embryos, L1 and L2. In L3, in addition to these disaccharides, we also detected significant amount of 6-sulfated units that are reported here for the first time. Immunohistochemical analysis indicated that HS and CS were present in nonequivalent structures in adult and larval stages of the fly. Overall, these results indicate that (35)S-sulfate-precursors are transferred from adult to embryonic and larval tissues and used to assemble different morphological structures during development.