Biology subjects

Sankaranarayanan, S.

Publications and source records attributed to Sankaranarayanan, S..

3 recordsLinked to original sources

bioRxiv2020

Complement factor C1q mediates chronic neuron loss and inflammation post-brain injury

While traumatic brain injury (TBI) acutely disrupts the cortex, most TBI-related disabilities reflect secondary injuries that accrue over time. The thalamus is a likely site of secondary damage because of its reciprocal connections with the cortex. Using a mouse model of cortical injury that does not directly damage subcortical structures, we found a chronic increase in C1q expression specifically in the corticothalamic circuit. Increased C1q expression co-localized with neuron loss and chronic inflammation, and correlated with altered cortical rhythms. Blocking C1q counteracted most of these outcomes, suggesting that C1q is a disease modifier in TBI. Since the corticothalamic circuit is important for sensory processing, attention, cognition, and sleep, all of which can be impaired by TBI, this circuit could be a new target for treating TBI-related disabilities.

neuroscience↗

bioRxiv2020

Expression of Brassica napus GLO1 is sufficient to breakdown artificial self-incompatibility in Arabidopsis thaliana

Members of the Brassicaceae family have the ability to regulate pollination events occurring on the stigma surface. In Brassica species, self-pollination leads to an allele specific interaction between the pollen small cysteine-rich peptide ligand (SCR/SP11) and the stigmatic S-receptor kinase (SRK) that activates the E3 ubiquitin ligase ARC1 (Armadillo repeat-containing 1), resulting in proteasomal degradation of various compatibility factors including Glyoxalase I (GLO1) which is necessary for successful pollination. Suppression of GLO1 was sufficient to reduce compatibility, and overexpression of GLO1 in self-incompatible Brassica napus stigmas resulted in partial breakdown of the self-incompatibility response. Here, we verified if BnGLO1 could function as a compatibility factor in the artificial self-incompatibility system of Arabidopsis thaliana expressing AlSCRb, AlSRKb and AlARC1 proteins from A. lyrata. Overexpression of BnGLO1 is sufficient to breakdown self-incompatibility response in A. thaliana stigmas, suggesting that GLO1 functions as an inter-species compatibility factor. Therefore, GLO1 has an indisputable role as a compatibility factor in the stigma in regulating pollen attachment and pollen tube growth. Lastly, this study demonstrates the usefulness of an artificial self-incompatibility system in A. thaliana for interspecific self-incompatibility studies.

plant biology↗

bioRxiv2020

Stigma Receptivity is controlled by Functionally Redundant MAPK Pathway Components in Arabidopsis

In angiosperms, the process of pollination relies on species-specific interaction and signaling between the male (pollen) and female (pistil) counterparts where the interplay between several pollen and stigma proteins decides the fate of the pollen. In Brassicaceae, the dry stigmatic papillary cells control pollen germination by releasing resources only to compatible pollen thereby allowing pollen to hydrate and germinate. Despite the identification of a number of stigmatic proteins that facilitate pollination responses, the signaling mechanisms that regulate functions of these proteins have remained unknown. Here we show that, in Arabidopsis, an extremely functionally redundant mitogen-activated protein kinase (MAPK) cascade is required for maintaining stigma receptivity to accept compatible pollen. Our genetic analyses demonstrate that in stigmas, five MAPK kinases (MKKs), MKK1/2/3/7/9 are required to transmit upstream signals to two MPKs, MPK3/4, to mediate compatible pollination. Compromised functions of these five MKKs in the quintuple mutant (mkk1/2/3RNAi/mkk7/9) phenocopied pollination defects observed in the mpk4RNAi/mpk3 double mutant. We further show that this MAPK nexus converges on Exo70A1, a previously identified stigmatic compatibility factor essential for pollination. Given that pollination is the crucial initial step during plant reproduction, understanding the mechanisms that govern successful pollination could lead to development of strategies to improve crop yield.

plant biology↗