DSpace Coleção: Nota Técnica/Nota científica (CNPTIA)

Revisiting the cytogenetics of Vellozia Vand.: immunolocalization of KNL1 elucidates the chromosome number for the genus.

2025-03-16T06:45:36Z

Título: Revisiting the cytogenetics of Vellozia Vand.: immunolocalization of KNL1 elucidates the chromosome number for the genus. Autoria: BRAZ, G. T.; RIBOLDI, L. B.; PINTO, M. S.; FORNI-MARTINS, E. R.; YASSITEPE, J. E. de C. T.; DANTE, R. A.; GERHARDT, I. R. Conteúdo: Chromosome number is the most fundamental trait of a karyotype. Accurate chromosome counting is essential for further analyses including cytogenomics, taxonomic, evolutionary, and genomic studies. Despite its importance, miscounting is common, especially in early publications on species with small and morphologically similar chromosomes. Vellozia Vand. is a genus mainly distributed throughout South America belonging to the angiosperm family Velloziaceae, a dominant taxon in the Brazilian “campos rupestres”. Cytogenetic studies within the group have been rare and have shown conflicting chromosome counts, even within the same species. These discrepancies are associated with the presence of a few small chromosome-like structures, which were previously classified as possible satellites. Here, to accurately determine the chromosome number of species belonging to the genus, we used different cytogenomics approaches, including the immunostaining of the KNL1 kinetochore protein combined with chromosome spread preparation using tissue culture-derived samples. Our results revealed 2n = 18 chromosomes for all six species studied. This finding suggests that the basic chromosome number for Vellozia is x = 9 and not x = 8, as previously proposed. The immunolocalization of functional centromeres was fundamental for undoubtedly identifying the smaller chromosome pair as real chromosomes and accurately determining the correct chromosome number of these species. This will provide substantial support for further studies, including investigations into karyotype evolution and the generation of reference genomes for the species of the family.

Charting new sustainable agricultural innovation pathways in Brazil.

2025-03-16T04:21:24Z

Título: Charting new sustainable agricultural innovation pathways in Brazil. Autoria: MARTHA JUNIOR, G. B.; LOPES, M. A. Conteúdo: Advanced Biology. Digital Transformation. Production systems focusing on sustainable intensification approaches. Tropical Agriculture Perspectives in the Bioeconomy Era. Future Challenges.

Mitochondrial retrograde signaling through UCP1-mediated inhibition of the plant oxygen-sensing pathway.

2025-03-16T08:26:15Z

Título: Mitochondrial retrograde signaling through UCP1-mediated inhibition of the plant oxygen-sensing pathway. Autoria: BARRETO, P.; DAMBIRE, C.; SHARMA, G.; VICENTE, J.; OSBORNE, R.; YASSITEPE, J. E. de C. T.; GIBBS, D. J.; MAIA, I. G.; HOLDSWORTH, M. J.; ARRUDA, P. Conteúdo: SUMMARY. Mitochondrial retrograde signaling is an important component of intracellular stress signaling in eukaryotes. UNCOUPLING PROTEIN (UCP)1 is an abundant plant inner-mitochondrial membrane protein with multiple functions including uncoupled respiration and amino-acid transport1,2 that influences broad abiotic stress responses. Although the mechanism(s) through which this retrograde function acts is unknown, overexpression of UCP1 activates expression of hypoxia (low oxygen)-associated nuclear genes.3,4 Here we show in Arabidopsis thaliana that UCP1 influences nuclear gene expression and physiological response by inhibiting the cytoplasmic PLANT CYSTEINE OXIDASE (PCO) branch of the PROTEOLYSIS (PRT)6 N-degron pathway, a major mechanism of oxygen and nitric oxide (NO) sensing.5 Overexpression of UCP1 (UCP1ox) resulted in the stabilization of an artificial PCO N-degron pathway substrate, and stability of this reporter protein was influenced by pharmacological interventions that control UCP1 activity. Hypoxia and salt-tolerant phenotypes observed in UCP1ox lines resembled those observed for the PRT6 N-recognin E3 ligase mutant prt6-1. Genetic analysis showed that UCP1 regulation of hypoxia responses required the activity of PCO N-degron pathway ETHYLENE RESPONSE FACTOR (ERF)VII substrates. Transcript expression analysis indicated that UCP1 regulation of hypoxia-related gene expression is a normal component of seedling development. Our results show that mitochondrial retrograde signaling represses the PCO N-degron pathway, enhancing substrate function, thus facilitating downstream stress responses. This work reveals a novel mechanism through which mitochondrial retrograde signaling influences nuclear response to hypoxia by inhibition of an ancient cytoplasmic pathway of eukaryotic oxygen sensing.

Is our immune system a powerful vaccine factory?

2021-09-08T12:00:51Z

Título: Is our immune system a powerful vaccine factory? Autoria: YAMAGISHI, M. E. B.