A multicentre study on the clinical characteristics of newborns infected with coronavirus disease 2019 during the omicron wave.

Objective: To investigate the clinical characteristics and outcomes of newborns infected with coronavirus disease 2019 (COVID-19) during the Omicron wave. Methods: From December 1, 2022, to January 4, 2023, clinical data were collected from neonates with COVID-19 who were admitted to 10 hospitals in Foshan City, China. Their epidemiological histories, clinical manifestations and outcomes were analysed. The neonates were divided into symptomatic and asymptomatic groups. The t test or χ2 test was used for comparisons between groups. Results: A total of 286 children were diagnosed, including 166 males, 120 females, 273 full-term infants and 13 premature infants. They were 5.5 (0-30) days old on average when they were admitted to the hospital. These children had contact with patients who tested positive for COVID-19 and were infected through horizontal transmission. This study included 33 asymptomatic and 253 symptomatic patients, among whom 143 were diagnosed with upper respiratory tract infections and 110 were diagnosed with pneumonia. There were no severe or critical patients. Fever (220 patients) was the most common clinical manifestation, with a duration of 1.1 (1-6) days. The next most common clinical manifestations were cough with nasal congestion or runny nose (4 patients), cough (34 patients), poor appetite (7 patients), shortness of breath (15 patients), and poor general status (1 patient). There were no significant abnormalities in routine blood tests among the neonates infected with COVID-19 except for mononucleosis. However, compared with the asymptomatic group, in the symptomatic group, the leukocyte and neutrophil granulocyte counts were significantly decreased, and the monocyte count was significantly increased. C-reactive protein (CRP) levels were significantly increased (≥10 mg/L) in 9 patients. Myocardial enzyme, liver function, kidney function and other tests showed no obvious abnormalities. Conclusions: In this study, neonates infected with the Omicron variant were asymptomatic or had mild disease. Symptomatic patients had lower leucocyte and neutrophil levels than asymptomatic patients.

Transcription factor OsMADS25 improves rice tolerance to cold stress.

Cold stress is the limiting factor of rice growth and production, and it is important to clone cold stress tolerant genes and cultivate cold tolerance rice varieties. The MADS transcription factors play an important role in abiotic stress signaling in rice. This study showed that OsMADS25 was up-regulated by low temperature and abscisic acid (ABA), suggesting that OsMADS25 may be involved in ABA-dependent signaling. The OsMADS25 overexpression vector, pCambia1300-221-OsMADS25-Flag, was constructed and introduced into the rice variety Zhonghua 11 (ZH11) through Agrobacterium tumefacian-mediated genetic transformation. Two homozygous lines with high expression levels were selected for phenotypic identification. OsMADS25 overexpression lines show significantly improved cold stress tolerance and the sensitivity to ABA at the seedling stage of rice. Reactive oxygen species (ROS) was detected by diaminobenzidine (DAB) staining and nitroblue tetrazolium (NBT) staining. After treatment with cold stress, little ROS accumulation was observed in OsMADS25 overexpression lines compared to wild-type ZH11. In conclusion, OsMADS25 plays a role in scavenging reactive oxygen species (ROS) and could improve rice tolerance to cold stress involved in ABA-dependent pathway.

Improvement of the Rice "Easy-to-Shatter" Trait via CRISPR/Cas9-Mediated Mutagenesis of the qSH1 Gene.

"Easy-to-shatter" trait is a major cause of rice crop yield losses, emphasizing the economic value of developing elite rice cultivars with reduced seed shattering capable of achieving higher yields. In the present study, we describe the development of new indica rice lines that exhibit lower rates of seed shattering following the targeted CRISPR/Cas9-mediated editing of the qSH1 gene. We were able to identify qSH1 mutant T0 transgenic plants, with transgene-free homozygous mutants being obtained via segregation in the T1 generation. We then utilized two T2 transgene-free homozygous lines in order to assess the degree of seed shattering and major agronomic traits of these mutant lines and of wild-type rice plants (HR1128-WT). This approach revealed that qsh1 homozygous mutant lines exhibited significantly reduced seed shattering relative to HR1128-WT without any significant changes in other analyzed agronomic traits. We then used these mutant lines to develop new promising hybrid rice lines with intermediate seed shattering. Overall our results reveal that combining targeted gene editing via CRISPR/Cas9 with heterosis utilization approach can allow for the efficient development of novel promising hybrid rice cultivars that exhibit a intermediate of seed shattering, thereby ensuring better stability and improved rice yields.

Cyclic Digestion and Ligation-Mediated PCR Used for Flanking Sequence Walking.

Ligation-mediated PCR (LM-PCR) is a classical method for isolating flanking sequences; however, it has a common limitation of reduced success rate owing to the circularization or multimerization of target restriction fragments including the known sequence. To address this limitation, we developed a novel LM-PCR method, termed Cyclic Digestion and Ligation-Mediated PCR (CDL-PCR). The novelty of this approach involves the design of new adapters that cannot be digested after being ligated with the restriction fragment, and cyclic digestion and ligation may be manipulated to block the circularization or multimerization of the target restriction fragments. Moreover, to improve the generality and flexibility of CDL-PCR, an adapter precursor sequence was designed, which could be digested to prepare 12 different adapters at low cost. Using this method, the flanking sequences of T-DNA insertions were obtained from transgenic rice and Arabidopsis thaliana. The experimental results demonstrated that CDL-PCR is an efficient and flexible method for identifying the flanking sequences in transgenic rice and Arabidopsis thaliana.

QTL analysis and dissection of panicle components in rice using advanced backcross populations derived from Oryza Sativa cultivars HR1128 and 'Nipponbare'.

Panicle traits are among the most important agronomic characters which directly relate to yield in rice. Grain number (GN), panicle length (PL), primary branch number (PBN), and secondary branch number (SBN) are the major components of rice panicle structure, and are all controlled by quantitative trait loci (QTLs). In our research, four advanced backcross overlapping populations (BIL152, BIL196a, BIL196b, and BIL196b-156) carrying introgressed segments from chromosome 6 were derived from an indica/japonica cross that used the super-hybrid rice restorer line HR1128 and the international sequenced japonica cultivar 'Nipponbare' as the donor and recurrent parents, respectively. The four panicle traits, GN, PL, PBN, and SBN, were evaluated for QTL effects using the inclusive composite interval mapping (ICIM) method in populations over two years at two sites. Results showed that a total of twelve QTLs for GN, PL, PBN, and SBN were detected on chromosome 6. Based on marker loci physical positions, the QTLs were found to be tightly linked to three important chromosomal intervals described as RM7213 to RM19962, RM20000 to RM20210, and RM412 to RM20595. Three QTLs identified in this study, PL6-5, PBN6-1, and PBN6-2, were found to be novel compared with previous studies. A major QTL (PL6-5) for panicle length was detected in all four populations at two locations, and its position was narrowed down to a 1.3Mb region on chromosome 6. Near isogenic lines (NILs) carrying PL6-5 will be developed for fine mapping of the QTL, and our results will provide referable information for gene excavation of panicle components in rice.