Fonseca, R. N. d. | bioRxiv Science

bioRxiv2019

Genetic diversity by ISSR of two endemic quillworts (Isoetes L.) species from Amazon Iron Rocky Outcrops, Isoetes cangae e I. serracarajensis

Two lycophytes endemic species have been recently described at the State of Para, in the Amazon forest located in the North of Brazil. Genetic diversity and population structure of Isoetes cangae and I. serracarajensis were investigated through ISSR molecular markers. These analyses aim to establish strategies for future attempts for species conservation. From sixteen primers, 115 gel bands were identified from which 87% were polymorphic. A high level of polymorphic loci (81,74 % e 68,48 %) and a high Shannon index for intra populational genetic diversity was observed for each species (Sh=0.376 e 0.289) I. cangae and I. serracarajensis, respectively. The largest genetic diversity of both species relies in their own populations. The coefficient of genetic differentiation between population areas (GST) was higher in I. serracarajensis (0.5440) than in I. cangae (0.2250). Gene flow was high between I. cangae populations (1.7142) and very low in I. serracarajensis (0.4190). Principal Component Analysis (PCoA) showed that individual plants were allocated into species-specific and population groups. Overall, the results further show that I. serracarajensis (0.5440) and I. cangae are two species with considerable genetic variation. These results should be considered for effective conservation strategies of both species.

genetics↗

bioRxiv2017

Evolution And Multiple Roles Of The Pancrustacea Specific Transcription Factor zelda In Insects

Gene regulatory networks (GRN) evolve as a result of the coevolutionary process acting on transcription factors and the cis-regulatory modules (CRMs) they bind. The zinc-finger transcription factor (TF) zelda (zld) is essential for maternal zygotic transition (MZT) in Drosophila melanogaster, where it directly binds over thousand CRMs to regulate chromatin accessibility. D. melanogaster displays a long germ type of embryonic development, where all segments are simultaneously generated along the whole egg. However, it remains unclear if zld is also involved in MZT of short-germ insects (including those from basal lineages) or in other biological processes. Here we show that zld is an innovation of the Pancrustacea lineage, being absent in more distant arthropods (e.g. chelicerates) and other organisms. To better understand zlds ancestral function, we thoroughly investigated its roles in a short-germ beetle, Tribolium castaneum, using molecular biology and computational approaches. Our results demonstrate roles for zld not only during the MZT, but also in posterior segmentation and patterning of imaginal disc derived structures. Further, we also demonstrate that zld is critical for posterior segmentation in the hemipteran Rhodnius prolixus, indicating this function predates the origin of holometabolous insects and was subsequently lost in long-germ insects. Our results unveil new roles of zld in maintaining pluripotent state of progenitor cells at the posterior region and suggest that changes in expression of zld (and probably other pioneer TFs) are critical in the evolution of insect GRNs.

genetics↗