Morphological change and genome-wide transcript analysis of Haloxylon ammodendron leaf development reveals morphological characteristics and genes associated with the different C3 and C4 photosynthetic metabolic pathways

C4 photosynthesis outperforms C3 photosynthesis in natural ecosystems by maintaining a high photosynthetic rate and affording higher water-use and nitrogen-use efficiencies. C4 plants can survive in environments with poor living conditions, such as high temperatures and arid regions, and will be crucial to ecological and agricultural security in the face of global climate change in the future. However, the genetic architecture of C4 photosynthesis remains largely unclear, especially the genetic regulation of C4 Kranz anatomy. Haloxylon ammodendron is an important afforestation tree species and a valuable C4 wood plant in the desert region. The unique characteristic of H. ammodendron is that, during the seedling stage, it utilizes C3 photosynthesis, while in mature assimilating shoots (maAS), it switches to the C4 pathway. This makes an exceptional opportunity for studying the development of the C4 Kranz anatomy and metabolic pathways within individual plants (identical genome). To provide broader insight into the regulation of Kranz anatomy and non-Kranz leaves of the C4 plant H. ammodendron, carbon isotope values, anatomical sections and transcriptome analyses were used to better understand the molecular and cellular processes related to the development of C4 Kranz anatomy. This study revealed that H. ammodendron conducts C3 in the cotyledon before it switches to C4 in AS. However, the switching requires a developmental process. Stable carbon isotope discrimination measurements on three different developmental stages showed that young AS have a C3-like δ13C even though C4 Kranz anatomy is found, which is inconsistent with the anatomical findings. A C4-like δ13C can be measured in AS until they are mature. The expression analysis of C4 key genes also showed that the maAS exhibited higher expression than the young AS. In addition, many genes that may be related to the development of Kranz anatomy were screened. Comparison of gene expression patterns with respect to anatomy during leaf ontogeny provided insight into the genetic features of Kranz anatomy. This study helps with our understanding of the development of Kranz anatomy and provides future directions for studies on key C4 regulatory genes.

Anatomical observation and transcriptome analysis of buds reveal the association between the AP2 gene family and reproductive induction in hybrid larch (Larix kaempferi × Larix olgensis)

Hybrid larch is an excellent afforestation species in northern China. The instability of seed yield is an urgent problem to be solved. The biological characteristics related to seed setting in larch are different from those in angiosperms and other gymnosperms. Studying the developmental mechanism of the larch sporophyll can deepen our understanding of conifer reproductive development and help to ensure an adequate supply of seeds in the seed orchard. The results showed that the formation of microstrobilus primordia in hybrid larch could be observed in anatomical sections collected in the middle of July. The contents of endogenous gibberellin 3 (GA3) and abscisic acid (ABA) were higher and the contents of GA4, GA7, jasmonic acid and salicylic acid were lower in multiseeded larch. Transcriptome analysis showed that transcription factors were significantly enriched in the AP2 family. There were 23 differentially expressed genes in the buds of the multiseeded and less-seeded types, and the expression of most of these genes was higher in the buds than in the needles. We conclude that mid-July is the early stage of reproductive organ development in hybrid larch and is suitable for the study of reproductive development. GA3 and ABA may be helpful for improving seed setting in larch, and 23 AP2/EREBP family genes are involved in the regulation of reproductive development in larch.

Anatomical observation and clinical significance of the left gastric vein in laparoscopic radical gastrectomy

Background

The left gastric vein (LGV) plays an important role in laparoscopic radical gastrectomy (LRG). However, the anatomy of the LGV is complicated with significant variation, and it is often damaged and bleeding during LRG. The purpose of this study was to observe and analyze the anatomic types of the LGV in patients undergoing LRG and to explore its clinical significance.

Methods

A total of 217 patients who underwent LRG from June 2016 to December 2020 were included. LGVs were divided into four types according to the relationship between the LGV and peripheral arteries [celiac artery (CA)/common hepatic artery (CHA)/splenic artery (SA)] and the pancreas during LRG. If a LGV was damaged during surgery (resulting in bleeding), it was included in the bleeding group. Non-bleeding groups were included if there was no impairment to the LGV.

Results

A total of four types of LGVs were observed, of which type I was the most prevalent, accounting for 58.8% (n=121). In 21 patients (9.7%), the LGV was injured and hemorrhagic during LRG; and the type IV LGV injury bleeding rate was as high as 41.7% (5/12). Univariate analysis revealed that the extent of lymph node dissection (LND), pathological stage, tumor (T) stage, and type of LGV were significantly associated with LGV injury and hemorrhage (P<0.05). Multivariate analysis showed that enlarged LND, late T stage, late pathological stage, and type IV LGV were independent risk factors for LGV injury hemorrhage.

Conclusions

LGVs that run between the CHA (posterior) and the CA into the portal venous system were the most common anatomical type. A LGV that runs between the SA (posterior) and the CA into the portal venous system is easily injured (resulting in bleeding). LGV injury and hemorrhage are affected by a variety of factors, and therefore, careful intraoperative dissection is necessary to avoid damage to the LGV.