Microalgae possess high photosynthetic efficiency, robust adaptability, and substantial biomass, serving as excellent biological resources for large-scale cultivation. Malic enzyme (ME), a ubiquitous metabolic enzyme in living organisms, catalyzes the decarboxylation of malate to produce pyruvate, CO₂, and NAD(P)H, playing a role in multiple metabolic pathways including energy metabolism, photosynthesis, respiration, and biosynthesis. In this study, we identified the Scenedesmus quadricauda malic enzyme gene (SqME) and its biological functions, aiming to provide excellent target genes for the genetic improvement of higher plants. Based on the RNA-seq data from S. quadricauda under the biofilm cultivation mode with high CO₂ and light energy transfer efficiency and small water use, a highly expressed gene (SqME) functionally annotated as ME was cloned. The physicochemical properties of the SqME-encoded protein were systematically analyzed by bioinformatics tools. The subcellular localization of SqME was determined via transient transformation in Nicotiana benthamiana leaves. The biological functions of SqME were identified via genetic transformation in Nicotiana tabacum, and the potential of SqME in the genetic improvement of higher plants was evaluated. The ORF of SqME was 1 770 bp, encoding 590 amino acid residues, and the encoded protein was located in chloroplasts. SqME was a NADP-ME, with the typical structural characteristics of ME. The ME activity in the transgenic N. tabacum plant was 1.8 folds of that in the wild-type control. Heterologous expression of SqME increased the content of chlorophyll a, chlorophyll b, and total chlorophyll by 20.9%, 26.9%, and 25.2%, respectively, compared with the control. The transgenic tobacco leaves showed an increase of 54.0% in the fluorescence parameter NPQ and a decrease of 30.1% in Fo compared with the control. Moreover, the biomass, total lipids, and soluble sugars in the transgenic tobacco leaves enhanced by 20.5%, 25.7%, and 9.5%, respectively. On the contrary, the starch and protein content in the transgenic tobacco leaves decreased by 22.4% and 12.2%, respectively. Collectively, the SqME-encoded protein exhibited a strong enzymatic activity. Heterologous expressing of SqME could significantly enhance photosynthetic protection, photosynthesis, and biomass accumulation in the host. Additionally, SqME can facilitate carbon metabolism remodeling in the host, driving more carbon flux towards lipid synthesis. Therefore, SqME can be applied in the genetic improvement of higher plants for enhancing photosynthetic carbon fixation and lipid accumulation. These findings provide scientific references for mining of functional genes from S. quadricauda and application of these genes in the genetic engineering of higher plants.
Nicotiana/genetics* ; Photosynthesis/physiology* ; Malate Dehydrogenase/biosynthesis* ; Plant Leaves/genetics* ; Scenedesmus/enzymology* ; Carbon Cycle/genetics* ; Lipid Metabolism/genetics* ; Plants, Genetically Modified/metabolism*

Objective:To assess the value of combined chromosomal karyotyping and chromosomal microarray analysis (CMA) and/or copy number variation sequencing (CNV-seq) for the prenatal diagnosis for women with advanced maternal ages, and to explore the challenges of prenatal genetic counseling brought by the types of fetal CNVs and uncertainty of related phenotypes.Methods:A retrospective analysis was carried out on 1 841 women with advanced maternal age who underwent interventional prenatal diagnosis at the Prenatal Diagnosis Center of Xiamen University Affiliated Women and Children′s Hospital from January 2017 to December 2020. Routine chromosomal karyotyping analysis and CMA/CNV-seq detection were carried out.Results:CMA/CNV-seq had detected pathogenic variants in 2 cases which had failed karyotyping analysis. Two hundred and twenty one fetal chromosomal abnormalities were detected by karyotyping analysis, among which 187 were detected by CMA/CNV-seq. CMA/CNV-seq analysis of 23 cases with balanced chromosome structural aberrations and 10 cases with low proportion mosaicisms (including a marker chromosome) had yielded a negative result. In addition, 26 cases (26/1 841, 1.4%) with pathogenic CNVs were discovered among those with a normal karyotype, of which 13 (50.0%) were recurrent CNVs associated with neurocognitive impairment, with 22q11.21 microdeletions and microduplications being the most common types (26.92%).Conclusion:The combination of karyotyping analysis and CMA/CNV-seq not only increased the rate of prenatal diagnosis, but also complemented with each other, which has facilitated genetic counseling and formulation of prenatal diagnosis strategy for the affected families.

OBJECTIVE: To investigate the perinatal clinical phenotype and genetic characteristics of two fetuses with ring chromosome 21 mosaicisms. METHODS: Two fetuses who were diagnosed at the Xiamen Maternal and Child Health Care Hospital in November 2021 were selected as the study subjects. Clinical data of the two fetuses were collected. Conventional G-banded karyotyping and chromosomal microarray analysis (CMA) were carried out for the fetuses and their parents. RESULTS: Prenatal ultrasonography of fetus 1 has revealed absence of nasal bone, ventricular septal defect, persistent left superior vena cava, and mild tricuspid regurgitation. Chromosomal karyotyping was 46,X?,dic r(21;21)(p12q22;q22p12)[41]/45,X?,-21[9]. CMA has revealed a 30.00 Mb quadruplication at 21q11.2q22.3 and a 3.00 Mb deletion at 21q22.3. For fetus 2, ultrasonography has revealed pointed echo of the nasal bone. The fetus was found to have a karyotype of 46,X?,r(21)(p12q22)[83]/45,X?,-21[14]/46,X?,dic r(21;21)(p12q22;q22p12)[3]. CMA has revealed a 5.10 Mb quadruplication at 21q22.12q22.3 and a 2.30 Mb deletion at 21q22.3. CONCLUSION The perinatal phenotype of the two fetuses with ring chromosome 21 mosaicisms is related to the duplication of chromosomal segments near the breakpoints of the chromosomal deletions. The combined chromosomal karyotyping and CMA has enabled prenatal diagnosis and genetic counseling for these families.
Pregnancy ; Female ; Humans ; Mosaicism ; Ring Chromosomes ; Vena Cava, Superior ; Chromosome Aberrations ; Prenatal Diagnosis ; Microarray Analysis ; Fetus/diagnostic imaging*

OBJECTIVE: To detect loss of heterozygosity (LOH) at human leukocyte antigen (HLA) loci in a Chinese patient with leukemia after haploidentical hematopoietic stem cell transplantation. METHODS: HLA genotyping was carried out on peripheral blood, hair follicle and buccal swab samples derived from the patient after the transplantation as well as peripheral blood samples from his parents by using PCR-sequence specific oligonucleotide probe method and PCR-sequence based typing method. Short tandem repeat (STR) loci were detected by using a 23 site STR assay kit and a self-developed 6 STR loci assay for the HLA regions. RESULTS: After the transplantation, the HLA genotype of the peripheral blood sample of the patient was identical to his father. The patient was HLA-A*02:01,24:02, C*03:03,03:04, B*13:01,15:01, DRB1*08:03,12:02, DQB1*03:01,06:01 for his hair follicle specimen. However, homozygosity of the HLA loci was found in his buccal swab sample. Only the HLA-A*24:02-C*03:03-B*15:01-DRB1*08:03-DQB1*06:01 haplotype from his father's was present, while the HLA-A*02:01-C*03:04-B*13:01-DRB1*12:02-DQB1*03:01 haplotype from his mother was lost. After the transplantation, the alleles of the 23 STR sites in the patient's peripheral blood sample were consistent to his father, with no allelic loss detected in his buccal swab sample. However, at least 4 STR loci in the HLA region were lost in his buccal swab sample. CONCLUSION LOH at the HLA loci has been detected in the buccal swab sample of a patient with leukemia who received haploidentical hematopoietic stem cell transplantation.
HLA Antigens/genetics* ; HLA-A Antigens/genetics* ; Histocompatibility Antigens Class I/genetics* ; Humans ; Leukemia/genetics* ; Loss of Heterozygosity