Biology subjects

Martina, S.

Publications and source records attributed to Martina, S..

3 recordsLinked to original sources

bioRxiv2023

The universe is asymmetric, the mouse brain too.

Hemispheric brain asymmetry is a basic organizational principle of the human brain and has been implicated in various psychiatric conditions, including autism spectrum disorder. Brain asymmetry is not a uniquely human feature and is observed in other species such as the mouse. Yet, asymmetry patterns are generally nuanced, and substantial sample sizes are required to detect these patterns. In this pre-registered study, we use a mouse dataset from the Province of Ontario Neurodevelopmental Network, which comprises structural MRI data from over 2000 mice, including genetic models for autism spectrum disorder, to reveal the scope and magnitude of hemispheric asymmetry in the mouse. Our findings demonstrate the presence of robust hemispheric asymmetry in the mouse brain, such as larger right hemispheric volumes towards the anterior pole and larger left hemispheric volumes toward the posterior pole, opposite to what has been shown in humans. This suggests the existence of species-specific traits. Further clustering analysis identified distinct asymmetry patterns in autism spectrum disorder models, a phenomenon that is also seen in atypically developing participants. Our study shows potential for the use of mouse models in studying the biological bases of typical and atypical brain asymmetry but also warrants caution as asymmetry patterns seem to differ between humans and mice.

neuroscience↗

bioRxiv2023

Regulation of Oocyte Meiotic Maturation: Unraveling the Interplay between PKA Inhibition and Cdk1 Activation

Oocyte meiosis is arrested at the first prophase stage, until hormonal stimulation triggers progression into the meiotic divisions. This process, called meiotic maturation, depends on extensive post-transcriptional events. In all vertebrates, two bottleneck events orchestrate meiosis resumption: first, the inhibition of PKA and, second, the activation of Cdk1, the master regulator of eukaryotic cell division. However, the molecular events occurring between these two steps are almost unknown. To address this issue, we took advantage of a Cdk1 inhibitor to identify the early events that depend on PKA downregulation and occur independently of Cdk1 activity. Unexpectedly, we show that accumulation of Cyclin B1 and Mos, the kinase responsible for MAPK activation in oocytes, are regulated in an opposing manner by a two-step mechanism. PKA downregulation induces first the accumulation of Cyclin B1 without any increase of its translation, independently of Cdk1 activation. Subsequently, the rate of Cyclin B1 translation increases in response to Cdk1 activation. In contrast, Mos translation begins downstream PKA inhibition, but the protein does not accumulate until Cdk1 is activated. These intertwined regulations create the positive feedback loops required for the full activation of Cdk1. Additionally, we show that two consecutive waves of translation occur during the G2-M transition, the first induced by PKA inhibition and the second by Cdk1 activation. Finally, we demonstrate that Arpp19, the only known early substrate of PKA in Xenopus oocytes, is not involved in the control of these early events. This study reveals that PKA downregulation promotes multiple molecular pathways that converge on the activation of Cdk1 to induce the G2/M transition in vertebrate oocytes.

cell biology↗

bioRxiv2020

PSK signaling controls ABA homeostasis and promotes shoot growth under mannitol stress

Water deficit impairs growth and survival of plants. Many water stress responses are under control of abscisic acid (ABA) but little is known about growth control under osmotic stress. Based on the previously described growth-promoting activity of the peptide hormone phytosulfokine (PSK), we hypothesized that it may contribute to growth regulation under water stress conditions. To test this hypothesis, we analyzed the Arabidopsis thaliana PSK receptor (PSKR) null mutant pskr1-3 pskr2-1 under mannitol and drought stress. In particular under mild water stress, fresht weight and photosynthetic efficiency were more reduced in pskr1-3 pskr2-1 than in wild type. Hydroponic and grafting experiments showed that PSKR signaling was not required for long-distance signaling from mannitol-stressed roots to shoot but rather for cell growth promotion in the shoot. Unlike wild type, pskr1-3 pskr2-1 shoots did not accumulate ABA in response to mannitol, showed misregulation of ABA synthesis genes and elevated expression of ABI1 and ABI2, repressors of ABA signaling whereas application of ABA partially reversed shoot growth inhibition by mannitol in pskr1-3 pskr2-1. In turn, mannitol and ABA induced expression of PSK3 and PSKR1, and ABA promoted expression of PSK2 and PSK4 revealing feedback regulatory loops between PSKR and osmotic stress signaling. HighlightPhytosulfokine receptor signaling regulates ABA synthesis and signaling genes and promotes ABA accumulation in the shoot of water-stressed plants and maintains leaf growth and photosynthetic efficiency which ensures plant health.

plant biology↗