Biology subjects

Vasudevan, V.

Publications and source records attributed to Vasudevan, V..

4 recordsLinked to original sources

bioRxiv2025

Maternal control of RNA decay safeguards embryo development

As in mammals, the plant embryo is surrounded by maternal tissues that provide protection from the external environment. In angiosperms, a double fertilization process results in the formation of a diploid embryo and a triploid endosperm, both of which develop within maternal sporophytic integuments. Thus, the seed of angiosperms is a combined structure of three genetically distinct components: embryo, endosperm, and maternal integuments. It has long been assumed that the maternal plant influences embryo development, but there is limited molecular evidence for a direct pathway through which the maternal sporophyte aYects embryogenesis. Here we show that secondary small interfering RNAs (siRNAs) generated upon exosome impairment lead to embryo abortion through a maternal sporophytic eYect. Depletion of the core subunit of the RNA-processing exosome RRP45B (CER7) causes globular embryo arrest connected to ectopic post-transcriptional gene silencing (PTGS). Seed coat expression of CER7 suppresses seed abortion, demonstrating a maternal sporophytic control of embryo development through an RNA decay safeguard pathway. Our data support a model in which a primary siRNA trigger originates in the maternal integuments of the cer7 seed coat and drives PTGS amplification in reproductive tissues after fertilization, ultimately leading to seed abortion. In addition, our genetic and molecular data suggest that overloading of AGO1 with siRNAs impairs miRNA function, likely leading to embryo arrest. Our data highlight the complex interplay between maternal and embryonic gene regulation, reinforcing the importance of controlled RNA decay in plant development.

plant biology↗

bioRxiv2024

Emergence of Pre-movement Beta Activity with Stable Sensorimotor Predictions to Facilitate Motor Adjustments

Adaptive behavior enables flexible responses to environmental changes. This process is particularly crucial when transitioning between environments with different features, relying on the progressive formation of expectations based on prior experience. In humans, beta oscillations are central to adaptive behavior. Yet, the brain mechanisms underlying the detection of environmental changes, and the iterative update needed to progressively improve behavioral performance remain elusive. Here, we reveal that beta activity emerges in a cerebello-cortical network two seconds before action initiation, as the features of a new environment become known and behavioral outcomes become more predictable. Within this period, the cerebellum and parietal cortex drive prefrontal activity to form expectations. Using a single-trial approach, we establish that beta bursts before action initiation predict performance in the upcoming trial based on previous outcomes. These findings uncover a novel anticipatory mechanism that reflects predictive processes critical for stabilizing performance and adapting to environmental changes.

neuroscience↗

bioRxiv2023

Defining the contribution of microRNA-specific slicing Argonautes in animals

microRNAs regulate gene expression through interaction with an Argonaute protein family member. While some members of this protein family retain an enzymatic activity capable of cleaving RNA molecules complementary to Argonaute-bound small RNAs, the role of the slicing activity in the canonical microRNA pathway is still unclear in animals. To address the importance of slicing Argonautes in animals, we created Caenorhabditis elegans strains, carrying catalytically dead endogenous ALG-1 and ALG-2, the only two slicing Argonautes essential for the miRNA pathway in this animal model. We observe that the loss of ALG-1 and ALG-2 slicing activity affects overall animal fitness and causes phenotypes, reminiscent of miRNA defects, only when grown and maintained at restrictive temperature. Furthermore, the analysis of global miRNA expression shows that the catalytic activity of ALG-1 and ALG-2 differentially regulate the level of specific subsets of miRNAs in young adults. We also demonstrate that altering the slicing activity of those miRNA-specific Argonautes does not result in any defect in the production of canonical miRNAs. Together, these data support that the slicing activity of miRNA- specific Argonautes function to maintain the levels of a set of miRNAs for optimal viability and fitness in animals particularly exposed to specific growing conditions.

molecular biology↗

bioRxiv2020

A displacement and velocity based dual model of saccadic eye movements best explains kinematic variability

Noise is a ubiquitous component of motor systems which leads to behavioral variability of all types of movements, including saccadic eye movements. Nonetheless, systems-based models of saccadic eye movements are deterministic and do not explain the observed saccade variability, only their central tendencies. Using stochastic models, we studied the variability in saccade behavior to test and distinguish between previously proposed deterministic saccade models. For this, the inter-trial variability in saccade displacement trajectories of human subjects was quantified while they performed repeated saccadic eye movements to a peripheral target. Based on fits to the data, we showed that existing models based on either displacement or velocity failed to capture the observed patterns in the variability of saccade trajectories. However, the observed behavior was captured by a dual control system, using a combination of displacement and velocity signal. The proposed model fits the mean displacement trajectory as well as the existing deterministic models. Taken together, our results suggest that the saccade system uses both desired displacement and velocity information. New and NoteworthyWe studied saccade behavior with a focus on the variability of the saccade trajectory. A stochastic model of the saccade system suggests that a dual control involving the control of displacement and velocity explains saccade behavior better than previously proposed models that utilize only displacement or velocity information. Our study resolves previous ambiguity regarding the use of displacement or velocity signals to guide saccades and provides a natural explanation for neural recordings that indicate multiplexing of displacement and velocity related information in the firing activity of neurons in the superior colliculus, a critical node in the oculomotor network that codes for saccadic eye movements.

neuroscience↗