Melhor Comunicação Oral – Prémio Prof. Doutor Amândio Sampaio Tavares
Ana Raquel Soares1,2, Marisa Reverendo1, Miguel Pinheiro3, Manuel Santos1
1
RNA Biology Laboratory, Department of Biology & CESAM, University of Aveiro, 3810-193
Aveiro, Portugal.
2
Faculdade de Farmácia, Universidade de Coimbra, Pólo das Ciências da Saúde, Azinhaga de
Santa Comba, 3000-548 Coimbra, Portugal
3
Biocant, Parque Tecnológico de Cantanhede, Bioinformatic Unit, Núcleo 04, Lote 3, 3060 197 Cantanhede - Portugal
arsoares@cnc.cj.uc.pt
Small non-coding RNAs are a class of transcripts implicated in several eukaryotic regulatory
mechanisms, such as post-transcriptional gene silencing or chromatin regulation, that
contribute to both the genome and the transcriptome supervision. Recently, we have applied
454 DNA pyrosequencing technologies to miRNA discovery in zebrafish and were able to
identify novel miRNAs. Analysis of the remaining reads revealed sequences derived from
tRNAs, snRNAs, snRNAs and rRNAs. RNA sequences derived from these abundant RNA species
are often considered as random degradation products when they are identified during deep
sequencing of small RNA fractions. However, after computational analysis of these sequences
we have identified 12 abundant RNA fragments, derived from precise processing at the 5’ or 3’
of mature or pre-tRNAs with precise sequence structures of 20 or 30 nt in length. In addition,
Northern Blot analysis confirmed the sequencing data and revealed tissue specific expression
for some of the tRNA derived fragments (tRNAfs), indicating that they are likely produced by
specific processing rather than random degradation. We also demonstrate that the production
of two of these fragments is Dicer dependent. An analysis of the shape probability revealed
that some mature tRNAs originating these particular tRNAfs have high probability (>80%) to
fold in pre-miRNA like structures, thus being ideal candidates for Dicer cleavage. Moreover, we
show that these tRNAfs associate with Ago proteins, key components of the RISC complex,
indicating that these new molecules enter the RNAi pathway and may be functional. In
addition, computational and Northern Blot analysis of tRNAfs in different vertebrate cell lines
revealed that these tRNAfs are conserved between vertebrates. We postulate that tRNAfs
represent a novel class of regulatory RNAs that have evolved early in vertebrates and may be
involved in ancient mechanisms of genome regulation.
Melhor Comunicação em Painel – Prémio Prof. Doutor Luís Archer
Genotyping of Castanea hybrid pedigrees for the construction of the first
linkage map related with disease resistance to P. cinnamomi
Carmen Santos1*, Fábio Tavares1, Helena Machado1, Thomas Kubisiak2 and Rita
Costa1
1Laboratório
de Biologia Molecular – L-INIA - Instituto Nacional dos Recursos Biológicos
I.P. - Quinta do Marquês, Av. da República 2780-159 Oeiras, PORTUGAL
2USDA
Forest Service, Southern Research Station, Southern Institute of Forest
Genetics, 23332 Old Mississippi Highway 67, Saucier, MS, USA.
carmen.santos@inrb.pt
Simple sequence repeats (SSRs) have proven to be extremely valuable DNA markers for genetic
mapping and population genetic analyses. Inter-specific crosses were initiated in 2006 for
introgression of resistance genes from Asian genotypes (Castanea crenata and Castanea
mollissima) into European genotypes (Castanea sativa), and the creation of a mapping
population for the identification of molecular markers related with disease resistance to
Phytophthora cinnamomi.
In 2006 and 2009, two full-sib progenies were obtained from two crosses, SC (C. sativa x C.
crenata) and SM (C. sativa x C. mollissima). The mapping population (parents and progenies)
have been genotyped with a set of SSRs designed for the genetic mapping pedigrees for
Castanea mollissima, provided by the American team of Fagaceae Genomics Project, and the
results are presented.
The genotyping of these pedigrees aims the construction of high density linkage maps for
further identification of QTLs related with disease resistance to P. cinnamomi. For this purpose
the metrics of resistance/susceptibility of each pedigree is also being determined.
Transcriptomic studies are also being implemented in order to identify candidate resistance
genes with further co-localization in the genetic linkage maps previously constructed.