Sousa, A. O. | bioRxiv Science

bioRxiv2022

Dynamics of annatto pigment synthesis and accumulation revealed by integrated chemical, anatomical, and RNA-Seq analyses

Bixin is a commercially valuable apocarotenoid pigment found in the seed aril of Bixa orellana. The dynamics and regulation of its biosynthesis and accumulation during seed development remain largely unknown. Here, we combined chemical, anatomical, and transcriptomic data to provide stage-specific resolution of the cellular and molecular events occurring during B. orellana seed development. Seeds at five developmental stages (S1-S5) were used for analysis of bixin content and seed anatomy, and three of them (S1, S3 and S4) selected for Illumina HiSeq sequencing. Bixin accumulated sharply during seed development, particularly during the S2 stage, peaking at the S4 stage, and then decreasing slightly in the S5 stage. Anatomical analysis revealed that bixin accumulated in the large central vacuole of specialized cells, which were scattered throughout the developing mesotesta at the S2 stage, but enlarged progressively at later stages, until they occupied most of the parenchyma in the aril. A total of 13 million reads were generated and assembled into 73,381 protein-encoding contigs, from which 312 were identified as containing 1-deoxy-D-xylulose-5-phosphate/2-C-methyl-D-erythritol-4-phosphate (DOXP/MEP), carotenoid, and bixin pathways genes. Differential expression analysis of these genes revealed that 50 of them were differentially expressed between all the seed developmental stages, including seven carotenoid cleavage dioxygenases, eight aldehyde dehydrogenases and 22 methyltransferases. Taken together, these results provide a comprehensive description of the cellular and molecular events related to the dynamics of bixin synthesis and accumulation during seed development in B. orellana.

plant biology↗

bioRxiv2021

The Trypanosoma cruzi kinetoplast DNA minicircle sequences transfer biomarker of the multidrug treatment of Chagas disease

BackgroundThe Trypanosoma cruzi infection renders the transfer of the mitochondrion kinetoplast DNA minicircle sequences into the hosts genome. The Aves are refractory to the infection, but chicks hatched from the T. cruzi inoculated eggs integrate the DNA minicircle sequences into the germ line cells. Rabbits, mice and chickens with the minicircle sequences mutations develop the Chagas cardiomyopathy and the DNA transfer underpins the heart disease. MethodologyThe PCR with the specific primer sets revealed the Protist nuclear DNA and the kinetoplast DNA in the agarose gels bands probed with the radiolabel specific sequences from tissues of the T. cruzi-infected rabbits and of the mice. A target- primer TAIL-PCR amplification employing primer sets from the chickens, rabbits and mice, in combination with primer sets from the the T. cruzi kinetoplast minicircle sequences was used. This approach led us to disclose the integration sites of the kinetoplast DNA biomarker, then, used to monitor the effect of multidrug treatment of the T. cruzi infected mice. Principal findingsThe Southern hybridization, clone and sequence of the amplification products revealed the DNA minicircle sequences integrations sites in the LINE transposable elements. An array of inhibitors of eukaryote cells division was used to arrest the DNA transfer. It was shown that nine out of 12 inhibitors prevented the kinetoplast DNA integration into the macrophage genome. The multidrug treatment of the acutely T. cruzi-infected mice with Benznidazole, Azidothymidine and Ofloxacin lessened circa 2.5-fold the rate of the minicircle sequences integrations in the mouse genome and inhibited the rejection of the target heart cells. Conclusion and significanceThe T. cruzi mitochondrion kinetoplast minicircle sequences transfer driven pathogenesis of Chagas disease is an ancient Cross-Kingdom DNA phenomenon of evolution and, therefore, paradigm research with effective purposing inhibitors is needed. Authors summaryChagas disease is considered the main cause of human heart failure in the Western Hemisphere. The treatment of the clinically manifested Chagas heart disease is considered unsatisfactory. Perhaps the most important problem in the field of Chagas disease is determination of the pathogenesis of the target heart cells lysis. We showed the transfer of the T. cruzi kDNA minicircle sequences into the genome of rabbits and mice, and to Bird refractory to the infections. The inoculation of a few T. cruzi in the fertile chicken eggs renders the kDNA sequences integration in the stem cells. Interestingly, the chicks that hatched retain the kDNA and develop the Chagas-like cardiomyopathy indistinguishable to that in the rabbits and mice. This result prompted the multidrug treatment of the Chagas heart disease with inhibitors of the eukaryotic cells division. We showed that nine out of 12 inhibitors prevented the transfer of the kDNA mutations into the macrophage genome, and that the treatment of the acutely T. cruzi-infected mice with Benznidazole + Ofloxacin + Azidothymidine lowered circa 2.5-fold the rate of the mutations in the chromosomes. These findings translated to the pathology showing inhibition of the heart lesions in the treated T. cruzi-infected mice. We suggest purposing new inhibitors should be tested to overturning the Chagas heart disease.

molecular biology↗