Biology subjects

Nalli, A.

Publications and source records attributed to Nalli, A..

3 recordsLinked to original sources

bioRxiv2025

CDM1 is required for meiotic progression and genome integrity during male meiosis in Arabidopsis

Microsporogenesis involves the integration of meiosis with the developmental program leading to formation of microspores from meiocytes. The CALLOSE DEFICIENT MICROSPORE 1 (CDM1) gene of Arabidopsis has been previously characterized as being required for callose metabolism and its loss results in defects in microspore wall development, degeneration of meiotic products, and male sterility. We report here that CDM1 is required for normal meiosis I progression, meiotic chromosome organization, and maintenance of DNA integrity. CDM1 is part of the ATM dependent DNA damage response in dividing vegetative tissues. The cdm1 mutant shows defects in meiotic chromosome condensation, arrest at metaphase I, susceptibility to chromosome breakage in rDNA regions, defects in positioning of the products of meiosis, and increased expression of recombination related genes. However, fidelity of chromosome segregation is not affected. Furthermore, the meiotic phenotype of cdm1 is independent of SPO11 induced meiotic double strand breaks. CDM1 protein displays granular localization in meiosis throughout the cytoplasm that resembles that of mRNP granules. The results show that CDM1 is required for maintenance of proper chromosome organization and DNA integrity in the course of male meiosis. The chromosomal defects in cdm1 may originate from regions of defective or incomplete replication. HighlightCDM1 expression is DNA damage inducible in Arabidopsis mitotic cells. CDM1 is required for genome integrity in male meiosis independent of SPO11-induced DNA breaks, suggesting a role in regulation of premeiotic replication repair.

plant biology↗

bioRxiv2024

Age-dependent Changes in a Chaperone Complex in the Mouse Heart

The exquisitely organized sarcomere, the unit of contraction of striated muscle, is a stable structure with slow turnover of its components. The myosin chaperone UNC-45 and its binding partners, Hsp90 and Hsp70, are required for the initial folding of the myosin head domain and the assembly of myosin into thick filaments. There is increasing evidence that the UNC-45 system has an important role during aging to preserve sarcomere organization. Its decline may be a key factor in sarcopenia. Unlike skeletal muscle, the UNC-45 system in cardiac muscle in aging heart has not been examined extensively. Here we show that Unc45b and Hsp70 are localized to sarcomeric Z-discs in the mouse heart. We further show that during aging, there is a decline in the levels of myosin heavy chain, Unc-45b and Hsp70, but not Hsp90. While the decrease in Unc45b appears to be at the mRNA level, the decrease in the levels of myosin and Hsp70 were not at the mRNA but at the protein level. We have reported that in skeletal muscle, there is a decline in both Unc45b and Hsp90, and here we show that there is no such decline of Hsp70 in skeletal muscle. Hsp70 levels also did not decline with age in the brain or the liver. This heart-specific decrease of Hsp70 through its function as an Unc45b/Hsp70 complex might account for the age-dependent worsening of cardiomyopathies, and through Hsp70s multiple Unc-45b-independent functions, affect the folding and assembly of many other proteins in the aging heart.

cell biology↗

bioRxiv2023

Archaeal origin translation proofreader imparts multialdehyde stress tolerance to land plants

Aldehydes, being an integral part of carbon metabolism, energy generation and signalling pathways, are ingrained in plant physiology. Land plants have developed intricate metabolic pathways which involve production of reactive aldehydes and its detoxification to survive harsh terrestrial environments. Here, we show that physiologically produced aldehydes i.e., formaldehyde and methylglyoxal in addition to acetaldehyde, generate adducts with aminoacyl-tRNAs, a substrate for protein synthesis. Plants are unique in possessing two distinct chiral proofreading systems, D-aminoacyl-tRNA deacylase1 (DTD1) and DTD2, of bacterial and archaeal origins, respectively. Extensive biochemical analysis revealed that only archaeal DTD2 can remove the stable D-aminoacyl adducts on tRNA thereby shielding archaea and plants from these system-generated aldehydes. Using Arabidopsis as a model system, we have shown that the loss of DTD2 gene renders plants susceptible to these toxic aldehydes as they generate stable alkyl modification on D-aminoacyl-tRNAs, which are recycled only by DTD2. Bioinformatic analysis identifies the expansion of aldehyde metabolising repertoire in land plant ancestors which strongly correlates with the recruitment of archaeal DTD2. Finally, we demonstrate that the overexpression of DTD2 offers better protection against aldehydes than in wild-type Arabidopsis highlighting its role as a multi-aldehyde detoxifier that can be explored as a transgenic crop development strategy.

plant biology↗