No abstract

Low temperature affects a broad spectrum of cellular components in plants, such as chloroplasts, as well as plant metabolism. on the other hand, pseudouridine (Ψ) synthases are required for the most abundant post-transcriptional modification of RNA in Escherichia coli. However, the role of rice Ψ synthases in regulating chloroplast development at low temperature remains elusive. in this study, we identified the rice thermo-sensitive chlorophyll-deficient (tcd3) mutant, which displays an albino phenotype before the 4-leaf stage and ultimately dies when grown at 20 °C, but can grow normally at 32 °C. Genetic analysis showed that the mutant trait is controlled by a single recessive nuclear gene (tcd3). Map-based cloning, complementation and knockout tests revealed that TCD3 encodes a chloroplast-localized Ψ synthase. TCD3 is a cold-induced gene that is mainly expressed in leaves. the disruption of TCD3 severely affected the transcript levels of various chloroplast-associated genes, as well as ribosomal genes involved in chloroplast rRNA assembly at low temperature (20 °C), whereas the transcript levels of these genes were normal at high temperature (32 °C). These results provide a first glimpse into the importance of rice Ψ synthase gene in chloroplast development at low temperatures.

The multi-domain GTPase (MnmE) is conservative from bacteria to human and participates in tRNA modified synthesis. However, our understanding of how the MnmE is involved in plant chloroplast development is scarce, let alone in rice. A novel rice mutant, thermo-sensitive chlorophyll-deficient mutant 8 (tcd8) was identified in this study, which apparently presented an albino phenotype at 20 °C but a normal green over 24 °C, coincided with chloroplast development and chlorophyll content. Map-based cloning and complementary test revealed the TCD8 encoded a multi-domain GTPase localized in chloroplasts. In addition, the disturbance of TCD8 suppressed the transcripts of certain chloroplast-related genes at low temperature, although the genes were recoverable to nearly normal levels at high temperature (32 °C), indicating that TCD8 governs chloroplast development at low temperature. The multi-domain GTPase gene in rice is first reported in this study, which endorses the importance in exploring chloroplast development in rice.

e14059 Background: Meningioma is the most common primary neoplasm of the central nervous system (CNS) in adults. Genetic variants ( NF2, AKT1, TRAF7 etc.) are strongly related to the subtypes of meningioma. TERT promoter mutation or homozygous CDKN2A and/or CDKN2B deletion are independent evidence for diagnosing WHO grade 3 meningioma according to 5th CNS WHO. Our study reclassifies meningiomas using a clinical and molecular real-world dataset. Methods: This study retrospectively analyzed the genomic alteration of 347 Chinese meningioma patients during 2019-2022. Next-generation sequencing (NGS) was performed to detect gene mutations in tumor samples. Results: TERT promoter mutation or CDKN2A/B deletion were identified in 11% (n = 39) of patients ( TERT 5.2%, CDKN2A 8.1%, CDKN2B 8.6%). Of these cases, histologic grade information was available for 26 patients, 14(53.8%) of whom were reclassified as WHO grade 3 meningiomas, including four histologic grade 1 and ten histologic grade 2. There is a male preponderance in reclassified patients (56.4% vs. 40.0%, p < 0.05), meanwhile the age showed no significant difference between them (average age: 54 vs 50, p = 0.11). The most frequently co-mutated gene was NF2. The proportion of TERT promoter mutation or CDKN2A/B deletion in NF2-mutant tumors was similar to NF2-wildtype tumors (10% vs. 11%, p > 0.05). Conclusions: In our study, 11% of Chinese adult meningioma patients found TERT promoter mutation or CDKN2A/B deletion and showed a male preponderance, among 53.8% of whom were reclassified as meningiomas WHO grade 3. Overall, these data advance the understanding of the significance of molecular profiling in the classification of meningioma patients according to the 5th WHO CNS.