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In this work I used time lapse brightfield microscopy to investigate cells division’s kinetics during the first developmental stages of annual- and non-annual species belonging to the three different hylogenetic clades. Annual killifishes of all three clades had cleavage times significantly longer when compared to their non-annual sister taxa (average 35 min vs. average 75 min), showing, for the first time, that cell cycle rate during cleavage, a trait thought to be rather volutionary conserved can undergo convergent evolutionary change in response to variations in life-history.

Complete list of KEG pathway analysis. (PDF 839 kb)

Mir-29 target D. rerio and M. musculus Ireb2 3′-UTR. A Expression of GFP assessed by cytofluorometric analysis. Fusion with Ireb2 3′-UTR of D. rerio. The gray column indicates the baseline fluorescence intensity of the construct without miR-29 mimic. The middle blue column indicates the fluorescence with miR-29 mimic and the red column the fluorescence of a construct (Δ) where the putative binding site for miR-29 in the Ireb2 3′-UTR was mutated to destroy complementarity. Statistical significance of fluorescence difference between baseline and co-injection with miR-29 mimics was evaluated by Student’s t-test (** P

Neuronal-specific kif5a promoter expression. Representative double-labelling immunohistochemistry for eGFP (green) and neuronal marker HuC/D (pink) in optic tectum of 20-week-old kif5a:sponge-29 fish. Periventricular gray zone (PGZ), Tectum opticum (TeO). Scale bar: 100Â Îźm. (PDF 1014 kb)

Mir-29 predicted target DEGs identification in N. furzeri kif5a: sponge-29. A Intersection of D. rerio miR-29 predicted target genes (from TargetScanFish 6.2, score ≤ –0.30) with N. furzeri sponge-29 DEGs. A total of 38 predicted target genes were found deregulated in kif5a:sponge-29 fish, 28/38 upregulated (B) and 10/38 downregulated (C), respectively. Gray, red and green box represent a conserved binding site in the 3′-UTR of N. furzeri, M. musculus, and H. sapiens, respectively. Yellow colored genes lack a conserved binding site in N. furzeri. Light blue box indicate a physical interaction between target gene e and miR-29 observed by cross-linking immunoprecipitation (CLIP-seq). 1-3-4 numbers are relative to gene dataset type in Fig. 3e. (PDF 78 kb)

Age dependent regulation of IRP2 in wild-type and tg(kif5aa:eGFP-sponge-29). A, B IRP2 western blot analysis at different age point of wild-type (A) and tg(kif5aa:eGFP-sponge-29) brains. Three biological replicates were used for age point. Îą-tubulin was used as loading control. (PDF 163 kb)

Prediction of miR-29 binding site in D. rerio Elna1 and col11a1a mRNAs. Representative 3â ˛-UTR of Elna1 (ENSDARG00000069994.1) and Col11a1a (ENSDARG00000026165.1), respectively, with indication of the predicted binding sites (from TargetScanFish 6.2). Black circles shows miR-29 binding site and blue table shows the score of all predicted microRNA binding sites, miR-29 has the highest score in both the 3â ˛-UTR genes according to TargetScanFish 6.2. (PDF 531 kb)

Mir-29 upregulation coincides with Ireb2 and Tfrc downregulation in mouse brain. A Quantification of pri-miR-29 cluster (pri-miR-29b-a; pri-miR-29b-c) in postnatal day 0 and 60 mouse brain. Both primary transcripts dramatically increase during postnatal development (P

BACKGROUND: Annual killifishes inhabit temporary ponds and their embryos survive the dry season encased in the mud by entering diapause, a process that arrests embryonic development during hostile conditions. Annual killifishes are present within three clades distributed in Africa (one East and one West of the Dahomey gap) and South America. Within each of these phylogenetic clades, a non-annual clade is sister taxon to a annual clade and therefore represent an example of convergent evolution. Early cleavage of teleost embryos is characterized by a very fast cell cycle (15-30 minutes) and lack of G1 and G2 phases. Here, we decided to investigate rates of early cleavage in annual killifishes. In addition, we specifically tested whether also annual killifish embryos lack G1 and G2 phases. RESULTS: We used time lapse brightfield microscopy to investigate cell division kinetics during the first developmental stages of annual- and non-annual species belonging to the three different phylogenetic clades. Annual killifishes of all three clades showed cleavage times significantly longer when compared to their non-annual sister taxa (average 35 min vs. average 75 min). Using FUCCI fluorescent imaging of the cell cycle after microinjection in the annual species Nothobranchius furzeri, we demonstrate that the first 5 division are synchronous and do not show a G1 phase. Cell cycle synchronization is lost after the 5th cleavage division. CONCLUSIONS: Our results show, for the first time, that cell cycle rate during cleavage, a trait thought to be rather evolutionary conserved can undergo convergent evolutionary change in response to variations in life-history.