A case of fetal isolated ventricular noncompaction with TNNT2 gene mutation and literature review.

BACKGROUND: Ventricular noncompaction (VNC) is a cardiomyopathy characterized by overdeveloped ventricular trabeculaes and deep recess, which has been rarely reported. CASE PRESENTATION: A 29-year-old Chinese pregnant woman with no obvious fetal abnormality in regular prenatal examination during first and second trimester. However, at 32 weeks of gestation, both obstetric growth scan and fetal echocardiogram revealed an enlarged heart with grid-like changes at the apical region. Eventually, the genetic and autopsy findings indicated the deceased infant with VNC. CONCLUSION: Isolated VNC could be detected prenatally, even during the late pregnancy. Fetuses suspected of VNC should be offered genetic tests.

Mapping quantitative trait loci for seed traits in Camelina sativa.

KEY MESSAGE: Genetic dissection of oil content and seed size in Camelina sativa was conducted by QTL mapping using a SNP-based linkage map and a recombinant inbred population. Camelina (Camelina sativa L. Crantz) is an oilseed crop that has great potential to provide sustainable feedstock for biofuel production and to improve dryland agriculture. A major breeding objective for camelina is to increase seed size and oil content. Understanding the genetics behind variations of seed size and associated traits such as oil content would help breeders develop varieties of increased oil yield that are more robust, easier to plant and harvest, and better for oil processing. In this study, we developed a recombinant inbred population derived from the two camelina accessions, Suneson and Pryzeth, with contrasting traits, especially seed size and oil content. Using 189 lines, a genetic map was constructed containing 2376 single nucleotide polymorphism markers spanning 2034.6 cM of 20 linkage groups with an average density of 1.5 cM per locus. Field trials were conducted for 2 years (2017 and 2018) in two environments (dryland and irrigated) in Bozeman, Montana. The results revealed important correlations of seed size with other associated traits such as oil content, pod size and seed number per pod. Significant QTLs were also discovered for these traits. The results of this study are the first step to isolate genes controlling seed development and oil accumulation and to develop advanced varieties of camelina better adapted to modern agriculture by marker-assisted breeding.

A fatty acid condensing enzyme from Physaria fendleri increases hydroxy fatty acid accumulation in transgenic oilseeds of Camelina sativa.

MAIN CONCLUSION: Co-expression of a lesquerella fatty acid elongase and the castor fatty acid hydroxylase in camelina results in higher hydroxy fatty acid containing seeds with normal oil content and viability. Producing hydroxy fatty acids (HFA) in oilseed crops has been a long-standing goal to replace castor oil as a renewable source for numerous industrial applications. A fatty acid hydroxylase, RcFAH, from Ricinus communis, was introduced into Camelina sativa, but yielded only 15 % of HFA in its seed oil, much lower than the 90 % found in castor bean. Furthermore, the transgenic seeds contained decreased oil content and the germination ability was severely affected. Interestingly, HFA accumulation was significantly increased in camelina seed when co-expressing RcFAH with a fatty acid condensing enzyme, LfKCS3, from Physaria fendleri, a native HFA accumulator relative to camelina. The oil content and seed germination of the transgenic seeds also appeared normal compared to non-transgenics. LfKCS3 has been previously characterized to specifically elongate the hydroxylated ricinoleic acid to lesquerolic acid, the 20-carbon HFA found in lesquerella oil. The elongation reaction may facilitate the HFA flux from phosphatidylcholine (PC), the site of HFA formation, into the acyl-CoA pool for more efficient utilization in triacylglycerol (TAG) biosynthesis. This was demonstrated by increased HFA accumulation in TAG concurrent with reduced HFA content in PC during camelina seed development, and increased C20-HFA in HFA-TAG molecules. These effects of LfKCS3 thus may effectively relieve the bottleneck for HFA utilization in TAG biosynthesis and the feedback inhibition to fatty acid synthesis, result in higher HFA accumulation and restore oil content and seed viability.

Pregnancy Outcomes of Non-Visualization of the Fetal Gallbladder from a Chinese Tertiary Single Centre and Literature Review.

OBJECTION: To explore the clinical features and prognosis of non-visualization of the fetal gallbladder (NVFGB). METHODS: Sixty-five cases diagnosed with NVFGB in the Peking University First Hospital were collected retrospectively from January 2019 to December 2020. RESULTS: Forty-nine cases were successfully followed up. Among them, the gallbladder of 21 fetuses (42.9%) was present in the later pregnancy. In the rest 28 cases (57.1%), the gallbladders were absent during the whole pregnancy. Eleven of twenty-eight fetuses (39.3%) with NVFGB were complicated with other structural anomalies. In the remaining 17 cases of isolated NVFGB (60.7%) during the whole pregnancy, there was one case of congenital biliary atresia, three cases of a small gallbladder, one case of gallstone and one case of the gallbladder with several septa inside. A total of nine cases (18.4%) underwent prenatal diagnosis, four of which revealed abnormal copy number variant (CNV) results. CONCLUSION: Nearly half of NVFGB could be noted during the later pregnancy. The persistent NVFGB during the pregnancy has a higher risk to complicate gallbladder abnormality, other structural anomalies and abnormal CNV results. Other structures, especially the heart, gastrointestinal and urinary system, should be carefully examined when NVFGB is suspected.

Mutagenesis of the FAE1 genes significantly changes fatty acid composition in seeds of Camelina sativa.

Camelina sativa is a re-emerging low-input oilseed crop that has great potentials. It is necessary to ameliorate camelina oils for optimized fatty acid composition that can meet different application requirements. Camelina seed contains significant amounts of C20-C24 very long-chain fatty acids (VLCFAs) that may not be desirable. We demonstrated that these VLCFAs can be effectively reduced by deactivating the Fatty Acid Elongase1 (FAE1) in camelina. The allohexaploid camelina contains three alleles of FAE1 genes. Ethyl methanesulfonate (EMS) induced mutation at the FAE1-B gene caused over 60% reduction of VLCFAs in seed. Homozygous knockout mutants were successfully created in a single generation by simultaneously targeting three FAE1 alleles using the CRISPR technology with an egg cell-specific Cas9 expression. VLCFAs were reduced to less than 2% of total fatty acids compared to over 22% in the wild type, and the C18 unsaturated fatty acids were concomitantly increased. The fae1 mutants were indistinguishable from wild type in seed physiology and plant growth. This study demonstrated that the CRISPR/Cas9 technology can be effectively applied to the polyploid crop camelina to rapidly obtain desired traits such as optimal fatty acid composition in its seed oil. Knocking out FAE1 also provides a means to increase the levels of oleic acid or α-linolenic acid in camelina oils that are desirable for industrial or food/feed uses.

Seed-specific suppression of ADP-glucose pyrophosphorylase in Camelina sativa increases seed size and weight.

BACKGROUND: Camelina (Camelina sativa L.) is a promising oilseed crop that may provide sustainable feedstock for biofuel production. One of the major drawbacks of Camelina is its smaller seeds compared to other major oil crops such as canola, which limit oil yield and may also pose challenges in successful seedling establishment, especially in dryland cultivation. Previous studies indicate that seed development may be under metabolic control. In oilseeds, starch only accumulates temporarily during seed development but is almost absent in mature seeds. In this study, we explored the effect of altering seed carbohydrate metabolism on Camelina seed size through down-regulating ADP-glucose pyrophosphorylase (AGPase), a major enzyme in starch biosynthesis. RESULTS: An RNAi construct comprising sequences of the Camelina small subunit of an AGPase (CsAPS) was expressed in Camelina cultivar Suneson under a seed-specific promoter. The RNAi suppression reduced AGPase activities which concurred with moderately decreased starch accumulation during seed development. Transcripts of genes examined that are involved in storage products were not affected, but contents of sugars and water were increased in developing seeds. The transgenic seeds were larger than wild-type plants due to increased cell sizes in seed coat and embryos, and mature seeds contained similar oil but more protein contents. The larger seeds showed advantages on seedling emergence from deep soils. CONCLUSIONS: Changing starch and sugar metabolism during seed development may increase the size and mass of seeds without affecting their final oil content in Camelina. Increased seed size may improve seedling establishment in the field and increase seed yield.

Identification of three genes encoding microsomal oleate desaturases (FAD2) from the oilseed crop Camelina sativa.

Camelina sativa is a re-emerging low-input oilseed crop that may provide economical vegetable oils for industrial applications. It is desirable to increase the monounsaturated oleic acid (cis-9-octadecenoic acid, 18:1), and to decrease polyunsaturated fatty acids (PUFA), linoleic (cis, cis-9,12-octadecadienoic acid, 18:2) and α-linolenic (all-cis-9,12,15-octadecatrienoic acid, 18:3) acids, in camelina oils to improve oxidative stability. 18:1 desaturation is mainly controlled by the microsomal oleate desaturase (FAD2; EC 1.3.1.35) encoded by the FAD2 gene. Three FAD2 genes, designated CsFAD2-1 to 3, were identified in camelina. Functional expression of these genes in yeast confirmed that they all encode microsomal oleate desaturases. Although the three CsFAD2 genes share very high sequence similarity, they showed different expression patterns. Expression of CsFAD2-1 was detected in all tissues examined, including developing seed, flower, as well as in vegetable tissues such as leaf, root, and stem. Transcripts of CsFAD2-2 and CsFAD2-3 were mainly detected in developing seeds, suggesting their major roles in storage oil desaturation in seed. The introns of the three CsFAD2 genes, which showed greater sequence variations, may provide additional resources for designing molecular markers in breeding. Furthermore, the roles of CsFAD2 in PUFA synthesis were demonstrated by mutant analysis and by antisense gene expression in camelina seed.

Generation of transgenic plants of a potential oilseed crop Camelina sativa by Agrobacterium-mediated transformation.

Camelina sativa is an alternative oilseed crop that can be used as a potential low-cost biofuel crop or a source of health promoting omega-3 fatty acids. Currently, the fatty acid composition of camelina does not uniquely fit any particular uses, thus limit its commercial value and large-scale production. In order to improve oil quality and other agronomic characters, we have developed an efficient and simple in planta method to generate transgenic camelina plants. The method included Agrobacterium-mediated inoculation of plants at early flowering stage along with a vacuum infiltration procedure. We used a fluorescent protein (DsRed) as a visual selection marker, which allowed us to conveniently screen mature transgenic seeds from a large number of untransformed seeds. Using this method, over 1% of transgenic seeds can be obtained. Genetic analysis revealed that most of transgenic plants contain a single copy of transgene. In addition, we also demonstrated that transgenic camelina seeds produced novel hydroxy fatty acids by transforming a castor fatty acid hydroxylase. In conclusion, our results provide a rapid means to genetically improve agronomic characters of camelina, including fatty acid profiles of its seed oils. Camelina may serve as a potential industrial crop to produce novel biotechnology products.

Expression pattern of diacylglycerol acyltransferase-1, an enzyme involved in triacylglycerol biosynthesis, in Arabidopsis thaliana.

Triacylglycerol (TAG) is the major carbon storage reserve in oilseeds such as Arabidopsis. Acyl-CoA:diacylglycerol acyltransferase (DGAT) catalyses the final step of the TAG synthesis pathway. Although TAG is mainly accumulated during seed development, and DGAT has presumably the highest activity in developing seeds, we show here that TAG synthesis is also actively taking place during germination and seedling development in Arabidopsis. The expression pattern of the DGAT1 gene was studied in transgenic plants containing the reporter gene beta-glucuronidase (GUS) fused with DNA sequences flanking the DGAT1 coding region. GUS activity was not only detected in developing seeds and pollen, which normally accumulate storage TAG, but also in germinating seeds and seedlings. Western blots showed that DGAT1 protein is present in several tissues, though is most abundant in developing seeds. In seedlings, DGAT1 is expressed in shoot and root apical regions, correlating with rapid cell division and growth. The expression of GUS in seedlings was consistent with the results of RNA gel blot analyses, precursor feeding and DGAT assay. In addition, DGAT1 gene expression is up-regulated by glucose and associated with glucose-induced changes in seedling development.