Ana Martínez Gómez

13. Mahmoudi & Cairns 2019, Sci Rep, doi.org/10.1038/s415...
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10. Chen & Sarnow 1995, Science, DOI: 10.1126/science.7536344
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5. Hansen et al. 2013, Nature,https://doi.org/10.1038/nature11993
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1. Liu & Chen 2022, Cell, DOI: 10.1016/j.cell.2022.04.021
2. Lasda & Parker 2014, RNA,http://www.rnajournal.org/cgi/doi/10.1261/rna.047126.114
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4. Zhang et al. 2013, Mol Cell, DOI: 10.1016/j.molcel.2013.08.017

📚 For a deeper dive into circRNAs in brain development and disease, check out: “Circular RNAs: Emblematic Players of Neurogenesis and Neurodegeneration”

DOI: doi.org/10.3390/ijms...

🧠 circRNAs are highly enriched in neural tissue (~20% of the transcriptome), localize in cytoplasm and synapses, increase during differentiation and aging, and show spatiotemporal expression independent of linear mRNAs 11-15.

🧩 circRNAs can be translated via internal initiation, challenging their classic label as non-coding 9,10.
This expands their regulatory potential, though the functional roles of endogenously produced proteins remain largely unclear.

circRNAs have diverse roles:
They primarily act as miRNA sponges, regulating gene expression 5.
They also modulate proteins—as decoys, scaffolds, and recruiters—and in the nucleus, boost host gene transcription, collectively influencing cell cycle, apoptosis, and cell survival 1,3,4,6,7,8.

🌀 circRNAs lack a 5′ cap and 3′ poly(A) tail and are generated through a noncanonical splicing process called back-splicing 1,2.
They are classified as ecRNAs, ciRNAs, or EIciRNAs, depending on whether they contain exons, introns, or both 3-4.

🧬 Circular RNAs (circRNAs) are single-stranded molecules once classified as non-coding, now emerging as crucial regulators of gene expression and protein dynamics.

Let's talk about circular RNA!! 🧬🧬

Read the review:
“Molecular mechanisms of circular RNA translation” DOI: doi.org/10.1038/s122...

#MolecularBiology #Genomics #Science #Transcriptomics #RNAbiology #GeneExpression

13. Gabi et al. 2010, Brain Behav Evol, doi:10.1159/000319872

9. Cunha et al. 2022, Front Neuroanat, doi:10.3389/fnana.2022.1048261
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Over generations, step changes → cohorts diverge in brain, body & neuron number.
Some clades (primates, parrots, songbirds) evolve bigger brains with more neurons; others (rodents, sauropsids, mammals) grow brains faster than neurons → lower density 3-6,13.
👉 Plasticity drives brain diversity.

Reaction norm model:
🌍 Environmental step changes (like density) shift whole cohorts into new scaling regimes.
🧬 Within a cohort, individual-level factors (genetics, epigenetics, microenvironment) decouple body, brain, and neuron numbers.

This pattern contradicts the “numerical matching” hypothesis, which predicts body, brain, and neuron number should always scale together 11, 12.
Instead, brain size and neuron number may be regulated by different mechanisms.

Across cohorts (different densities):
🐟 Larger fish → larger brains with up to 20× more neurons.
Neuron density = constant or decreasing.
📐 This mirrors well-known interspecies scaling patterns, even though all fish came from the same stock.

Within a cohort (same density):
🐟 Larger fish → larger brains, but not more neurons.
Animals with more neurons had higher neuron density instead.
⚡ This extends to fish the brain-scaling pattern seen within individuals of the same species in rodents and birds.

Across vertebrates, bigger species → bigger brains with more neurons 1-6.
But within a species, this often breaks down 3,7-9.
Tilapia are ideal to test: they keep growing + have adult neurogenesis 10.
Researchers raised them at low vs. high density → up to 30× body size variation in same-age fish.

Larger Fish Have Larger Brains With More Neurons Across but Not Within Cohorts Raised in Different Growth Conditions Teles et al. propose a model of brain evolution that explains how come fish with larger bodies have larger brains with more neurons across cohorts raised in different growth conditions, while individ....

🚨 New in J. Comp. Neurology: "Larger Fish Have Larger Brains With More Neurons Across but Not Within Cohorts Raised in Different Growth Conditions" 🐟🧠

DOI: doi.org/10.1002/cne....

#Neuroscience #BrainEvolution #ComparativeNeurobiology #Fish #Plasticity

Ancient viral DNA helps human embryos develop Hear the biggest stories from the world of science | 01 October 2025

This week on the pod:

🦠 How ancient viruses drive modern human development
🧬 How heat can fuel DNA computers
go.nature.com/42QSI7W

Sea urchin metamorphosis is maybe one of the most radical event in developmental biology. In just about an hour, these little pluteus larvae completely reorganize their entire body plan.

Very happy that this video got awarded an honorable mention by #NikonSmallWorld 😃

Xenopus laevis embryos 🐸✨

Photo taken by me 📸
#DevBio #Xenopus #Science #FrogEmbryos

CrAAVe-seq enables cell-type specific genetic screens in vivo at scale.
It opens the way to study essential genes in neurons, disease models, and aging—going far beyond what cell culture screens can reveal.

Result: scalable, in vivo CRISPRi screening that is both cell-type specific and cost-efficient.
It reveals essential genes in defined neuronal populations—something cell culture screens cannot do.

Result: scalable, in vivo CRISPRi screening that is both cell-type specific and cost-efficient.
It reveals essential genes in defined neuronal populations—something cell culture screens cannot do.

Each AAV also carries a “handle” flanked by lox sites. In Cre+ neurons, Cre inverts this handle, allowing PCR to selectively recover only the sgRNAs from these cells. This ensures that the screen reads reflect only the targeted neuronal population.

CrAAVe-seq delivers sgRNA libraries via AAV vectors into LSL-dCas9-KRAB mice. In these mice, only Cre+ neurons excise the Stop cassette and express dCas9-KRAB. The sgRNAs then guide dCas9-KRAB to DNA, silencing the target genes.