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Adrián Gonzalo @adriangonzalo.bsky.social · 10d

Sooooo well deserved!! Looking forward to learning all the new insights you will provide with your project😻

Reposted by Adrián Gonzalo

Schnittger Lab @schnittger-lab.bsky.social · Aug 25

After 12 years…

In 2014, a wild idea was born: to follow female meiosis in Arabidopsis in real time. After many trials (including experiments with quirky mutants where female organs developed inside out, and a few other unconventional ideas), we switched gears to image the male side.

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Reposted by Adrián Gonzalo

raphmercier.bsky.social @raphmercier.bsky.social · Aug 25

Preprint Alert! 🚨🧬
Not one, but two preprints!

Meiotic orientation of kinetochore at meiosis is inforced by...[see below]
www.biorxiv.org/content/10.1...

and

Unlocking meiotic crossovers next to plant centromere
www.biorxiv.org/content/10.1...

#meiosis4ever
#everythingisconnected

a thread👇

Monopolar orientation of kinetochores at meiosis is enforced by COHESINS and their regulators, CENP-C, and the deSUMOylase SPF2

The first division of meiosis is unique in its capacity to halve the ploidy of the future gametes. To this end, one key innovation compared to mitosis is the monopolar orientation of the pairs of sist...

www.biorxiv.org

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Reposted by Adrián Gonzalo

Magdalena Bohutínská @majdabohu.bsky.social · Jul 17

1/5 ✨Proud✨ to see our review with Katie Peichel as featured content in Trends_Ecol_Evo, with my beloved alpine lineages of Arabidopsis arenosa on the cover. Hope that you find it interesting! doi.org/10.1016/j.tree.2023.11.007

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Adrián Gonzalo @adriangonzalo.bsky.social · Jul 1

Check out the Views & News piece that Joiselle Fernandes and I wrote for @nature.com on the recent work from @amarques.bsky.social and colleagues about one of the most bizarre ways to do meiosis rdcu.be/euabu.

Explained for non-experts!

Diagram of two types of reproduction based on their meiosis. A. shows typical meiosis taking place in individuals with two copies of each chromosome (diploids) resulting in both male and female gametes carrying one copy of each chromosome. Fertilization restores the double copy for each chromosome. B. shows Canina meiosis in individuals carrying five copies of each chromosome (pentaploids) where male gametes only carry one copy of each chromosome and female gametes carry four copies of each chromosome. Fertilization restores the five copy for each chromosome.

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Adrián Gonzalo @adriangonzalo.bsky.social · Jun 18

Maybe holocentric chromosomes? Having centromeres dispersed all over the chromosome prevents loss of acentric fragments after breakage. Am I wrong, @amarques.bsky.social ?

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Adrián Gonzalo @adriangonzalo.bsky.social · Jun 18

Very interesting weirdo! Good job and congratulations!

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Adrián Gonzalo @adriangonzalo.bsky.social · Jun 4

En espagnol on dit "impulso meiótico" -> "impulsion méiotique"?

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Adrián Gonzalo @adriangonzalo.bsky.social · May 23

"Treasure your exceptions":

Jack Bateman @jbateman01.bsky.social · May 22

🤗 Distribution of haploid chromosomes into separate nuclei in two pathogenic fungi | Science www.science.org/doi/10.1126/...

Distribution of haploid chromosomes into separate nuclei in two pathogenic fungi

Nuclei define eukaryotes, enabling macromolecular compartmentalization and cellular regulation. Each nucleus is believed to contain one or more haploid sets of chromosomes (1N). However, we discovered...

www.science.org

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Adrián Gonzalo @adriangonzalo.bsky.social · May 9

Finally, I must thank the other co-authors: Kirsten Bomblies and Aditya Nayak for their essential contributions to this work. It would have not been possible without them!

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Adrián Gonzalo @adriangonzalo.bsky.social · May 9

Conclusion: we found synapsis dynamics is severely compromised in neo-tetraploids, while in established ones it is more efficient even than diploids, and hybrids display sub-optimal synapsis. The extent of these synapsis defects is correlated with the degree of meiotic instability. 8/8.

A schematic timeline of synapsis completion using HEI10 dynamics as a “developmental clock”. In diploids, there is still some extensive asynapsis at the onset of HEI10 accumulation that quickly declines and synapsis completes as HEI10 accumulates. In neo-tetraploids there is extensive asynapsis, regardless of how advanced HEI10 accumulation is. In hybrids (cross between neo- and established tetraploid), the progression seems similar to that of diploids, but often fails to complete synapsis at the end of the process. Established tetraploids, show the most efficient dynamics, as very little asynapsis is left when HEI10 accumulation begins.

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Adrián Gonzalo @adriangonzalo.bsky.social · May 9

So, why is it so bad for NEO-4X to have incomplete synapsis? We don’t know but we observed certain (non-linear, probably complex) correlation between the extent of asynapsis and crossover number. Excess of crossovers, we know, is a problem for polyploid meiosis 7/8.

Plot of crossover number vs extent of asynapsis, R2 = 0.608, P < 0.0001

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Adrián Gonzalo @adriangonzalo.bsky.social · May 9

But why is synapsis so messed up in NEO-4X? We observed defects compatible with problems during earlier stages: less pre-synaptic co-alignments, and slower dynamics elongation of synapsis initiation sites. 6/8.

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Adrián Gonzalo @adriangonzalo.bsky.social · May 9

We modeled the initial extent of synapsis, the pace of synapsis completion, and the final extent of asynapsis. This suggested that NEO-4X synapsis progress stalls even before HE10 accumulation begins. In summary: EST-4X > 2X > > HYB-4X >>>>>> NEO-4X. 5/8.

Some examples of meiocytes with different degrees of synapsis completion and different levels of HEI10 accumulation.
Plots showing comparisons between A. arenosa genotypes for the initial extent of synapsis, the pace of synapsis completion, and the final extent of asynapsis.

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Adrián Gonzalo @adriangonzalo.bsky.social · May 9

Are these defects associated with problems in synapsis progression? We used the dynamics of HEI10 as a “developmental clock”: many small foci at early stages, few bright foci in later stages, to measure how early/late is the completion of synapsis (measured by the disappearance of ASY1). 4/8

Using the level of HEI10 accumulation (what % of total signal accumulates at bright foci): The higher is the %, the later in the HEI10 dynamics we are.
Using the length of ASY1 signal as a negative proxy for the degree of synapsis completion: The lower the ASY1 length, the closer to synapsis completeness.
Plotting HEI10 accumulation level vs ASY1 length show the normal trend: the higher is the HEI10 accumulation level the lower is the ASY1 length. In other words: incomplete synapsis is associated to early stages of HEI10 accumulation, and vice versa; full synapsis is typical when HEI10 accumulation is high. HOWEVER, this is not the case for NEO-4X where there is no real progress of synapsis as HEI10 accumulates.

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Adrián Gonzalo @adriangonzalo.bsky.social · May 9

We analyzed this in Arabidopsis arenosa diploids (2X), newly induced tetraploids (NEO-4X), natural established tetraploids (EST-4X), and hybrids (EST-4X x NEO-4X), which have different levels of meiotic stability: 2X > EST-4X > HYB-4X >> NEO-4X. 3/8

Quantification of meiotic stability in NEO-4x, EST-4X and HYB-4X through the number of meiotic defects like quadrivalents (groups of four homologs associated by crossovers) and univalents (chromosomes that did not receive crossovers) in metaphase I. The frequency of these defects is correlated with the total number of crossovers (measured as the number of HEI10 foci).

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Adrián Gonzalo @adriangonzalo.bsky.social · May 9

Pairs of homologous chromosomes need to remain pair-wise associated during early meiosis thanks to the formation of the synaptonemal complex (synapsis) for a normal regulation of meiotic recombination, and fertility. But how messy can synapsis get in polyploids? Can polyploids solve this problem?2/8

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Adrián Gonzalo @adriangonzalo.bsky.social · May 9

Our latest work is out in @pnas.org! We have quantified and modeled the dynamics of early meiosis events, which can get really messy in polyploids (doubled number of chromosomes, double the trouble), but can also get fixed through adaptive evolution 🧵1/8.
www.pnas.org/doi/10.1073/...

Improved synapsis dynamics accompany meiotic stability in Arabidopsis arenosa autotetraploids | PNAS

During meiosis, the correct pairing, synapsis, and recombination of homologous chromosome pairs is critical for fertility of sexual eukaryotes. The...

www.pnas.org

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Adrián Gonzalo @adriangonzalo.bsky.social · Apr 23

A beautiful reminder that the classification of allo- and autopolyploid is indeed more complex than whether they have hybrid or non-hybrid origin.

Also, a beautiful reminder of how genome doubling can be a driver of agronomy-relevant innovations.

Great paper! www.nature.com/articles/s41...

Rapid formation of stable autotetraploid rice from genome-doubled F1 hybrids of japonica–indica subspecies - Nature Plants

This study details a process of duplicated (homoeologous) chromosome ‘scrambling’ in newly formed rice polyploids, indicating the possibility of natural ‘allo-to-autopolyploid’ evolution, with implica...

www.nature.com

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Reposted by Adrián Gonzalo

Takashi Akera Lab @takashiakeralab.bsky.social · Nov 14

Official website for EMBO meiosis 2025 is live now! Looking forward to seeing you in Switzerland next June! #meiosis4eva

meetings.embo.org/event/25-mei...

Meiosis: Exploring diversity to discover the fundamentals

Meiosis is an essential cell division for sexual reproduction and fertility across eukaryotes. It involves a series of tightly regulated processes, including entry into meiosis, pairing of homologs, …

meetings.embo.org

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