EGG CELL 1 contributes to egg-cell-dependent preferential fertilization in Arabidopsis

During double fertilization in angiosperms, the pollen tube delivers two sperm cells into an embryo sac; one sperm cell fuses with an egg cell, and the other sperm cell fuses with the central cell. It has long been proposed that the preference for fusion with one or another female gamete cell depends on the sperm cells and occurs during gamete recognition. However, up to now, sperm-dependent preferential fertilization has not been demonstrated, and results on preferred fusion with either female gamete have remained conflicting. To investigate this topic, we generated Arabidopsis thaliana mutants that produce single sperm-like cells or whose egg cells are eliminated; we found that although the three different types of sperm-like cell are functionally equivalent in their ability to fertilize the egg and the central cell, each type of sperm-like cell fuses predominantly with the egg cell. This indicates that it is the egg cell that controls its preferential fertilization. We also found that sperm-activating small secreted EGG CELL 1 proteins are involved in the regulation of egg-cell-dependent preferential fertilization, revealing another important role for this protein family during double fertilization.

A female in vivo haploid-induction system via mutagenesis of egg cell-specific peptidases

Crop breeding schemes can be significantly accelerated by using (doubled) haploid plants. In vivo haploid induction has been applied in plant breeding for decades but is still not available for all crops and genotypes, and haploidization rates are generally very low. Therefore, methodological improvements to and new concepts for haploidization are required. Here, we report a novel system for the induction of haploid plants by mutating genes encoding egg cell-specific aspartic endopeptidases (ECSs). We show that after successful sperm-egg cell fusion, ECSs play a critical role to ensure male and female nucleus fusion after fertilization. The ecs1 ecs2 double mutant can induce haploids by both selfing and hybridization in Arabidopsis and ECS mutation is also capable of producing haploids in rice. In summary, our study develops a novel approach for maternal haploidization and provides new insights into the molecular basis of fertilization.

[An exploratory clinical study of the efficacy and safety of tumor-infiltrating lymphocytes in the treatment of metastatic osteosarcoma]

Objective: To explore the safety and efficacy of tumor-infiltrating lymphocytes (TILs) extracted from tumor tissue in patients with pulmonary metastasis of osteosarcoma, the TILs were amplified in vitro to reach clinical dosage and reinfused to the patients combined with high-dose interleukin 2 (IL-2). Methods: Twelve subjects with pathologically diagnosed osteosarcoma were enrolled from December 2019 to June 20, 2021 in Shanghai General Hospital. All subjects progressed with metastasis after standard chemotherapy and failed multiple lines of treatments. Fresh tumor tissue was obtained from the metastatic site and extracted and amplified by Good Manufacturing Practice (GMP) workshop to produce TILs to clinical treatment dosage (10⁹-10¹¹). High-dose IL-2 (100 000-200 000 U/kg) was administered immediately after autogenous TILs infusion to promote the activation, proliferation and antitumor cytolytic activity in vivo. Adverse events (AE) were graded according to Common Terminology Criteria for Adverse Events (CTCAE) standard and tumor response was assessed according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. Results: One patient did not receive treatment due to failure in isolating TILs, total of 11 patients received a single re-infusion of autologous TILs. There were 10 males and 1 female with a median age of 19.9 years (12-33 years). Six of these patients received higher dose levels of 1.0×10¹⁰ TILs. The 11 patients were followed-up for 1 to 13 months and tolerated well. The most common adverse events reported were fever (10/11), constipation (3/11) and elevated gamma-glutamyl transferase (GGT) (3/11). The high incidence of fever was due to the IL-2 infusion. All patients experienced a transient drop in lymphocyte count and leukopenia leading to non-myeloid ablative lymphocyte clearance. The AE included grade 4 hematologic toxicity, including 8 cases of lymphocytopenia, 2 cases of neutropenia and 1 case of thrombocytopenia. No AE of neurotoxicity occurred. Of all the 11 patients, 9 patients got stable disease (SD) and 2 patients had progressive disease (PD). The disease control rate was 9/11. The median duration of SD was more than 4 months, and the maximum tumor volume decreased by close to 20%. Patient number 9 had sustained SD status for more than 6 months. Conclusions: TILs with in vitro expansion ability could be isolated from tumor tissues of advanced osteosarcoma patients. TILs amplified and reinfused in vitro have anti-osteosarcoma activity.

H3K27 methylation regulates the fate of two cell lineages in male gametophytes

During angiosperm male gametogenesis, microspores divide to produce a vegetative cell (VC) and a male germline (MG), each with distinct cell fates. The mechanism underlying determination of the MG cell/VC fate remains an important area of research, with many unanswered questions. Here, we report that H3K27me3 is essential for VC fate commitment in male Arabidopsis thaliana gametophytes; H3K27me3 erasure contributes to MG cell fate initiation. VC-targeted H3K27me3 erasure disturbed VC development and shifted the VC fate toward a gamete destination, which suggests that MG cells require H3K27me3 erasure to trigger gamete cell fate. Multi-omics and cytological analyses confirmed the occurrence of extensive cell identity transition due to H3K27me3 erasure. Therefore, we experimentally confirmed that MG cell/VC fate is epigenetically regulated. H3K27 methylation plays a critical role in guiding MG cell/VC fate determination for pollen fertility in Arabidopsis. Our work also provides evidence for two previous hypotheses: the germline cell fate is specified by the differential distribution of unknown determinants and VC maintains the default microspore program (i.e. the H3K27me3 setting) while MG requires reprogramming.

The parental contributions to early plant embryogenesis and the concept of maternal-to-zygotic transition in plants

The maternal-to-zygotic transition (MZT) is a major developmental transition in the life cycles of animals. It consists of two associated processes: maternal transcript clearance and zygotic genome activation (ZGA). The concept of MZT has been controversially discussed in plants. In this short review, we summarize recent advances in understanding the timing of ZGA and the similarities and differences between ZGA in eudicots and monocots. We discuss the parental contributions to the transcriptome of the proembryo and parental control of early embryogenesis, and we examine distinct differences in the ZGA between animals and plants, update relevant concepts on MZT, and highlight outstanding questions in this field.

New insights into cell-cell communications during seed development in flowering plants

The evolution of seeds is a major reason why flowering plants are a dominant life form on Earth. The developing seed is composed of two fertilization products, the embryo and endosperm, which are surrounded by a maternally derived seed coat. Accumulating evidence indicates that efficient communication among all three seed components is required to ensure coordinated seed development. Cell communication within plant seeds has drawn much attention in recent years. In this study, we review current knowledge of cross-talk among the endosperm, embryo, and seed coat during seed development, and highlight recent advances in this field.

SYP72 interacts with the mechanosensitive channel MSL8 to protect pollen from hypoosmotic shock during hydration

In flowering plants, hydration of desiccated pollen grains on stigma is a prerequisite for pollen germination, during which pollen increase markedly in volume through water uptake, requiring them to survive hypoosmotic shock to maintain cellular integrity. However, the mechanisms behind the adaptation of pollen to this hypoosmotic challenge are largely unknown. Here, we identify the Qc-SNARE protein SYP72, which is specifically expressed in male gametophytes, as a critical regulator of pollen survival upon hypoosmotic shock during hydration. SYP72 interacts with the MSCS-LIKE 8 (MSL8) and is required for its localization to the plasma membrane. Intraspecies and interspecies genetic complementation experiments reveal that SYP72 paralogs and orthologs from green algae to angiosperms display conserved molecular functions and rescue the defects of Arabidopsis syp72 mutant pollen facing hypoosmotic shock following hydration. Our findings demonstrate a critical role for SYP72 in pollen resistance to hypoosmotic shock through the MSL8 cascade during pollen hydration.

Pollen grains undergo desiccation and rehydration prior to germination and must survive osmotic shock. Here the authors show that the Qc-SNARE protein SYP72 is required for the localization of the mechanosensitive channel MSL8 at the plasma membrane and to maintain viability during rehydration.

Autophagy in sexual plant reproduction: new insights

Autophagy is a mechanism by which damaged or unwanted cells are degraded and their constituents recycled. Over the past decades, research focused on autophagy has expanded from yeast to mammals and plants, and the core machinery regulating autophagy appears to be conserved. In plants, autophagy has essential roles in responses to stressful conditions and also contributes to normal development, especially in the context of reproduction. Here, based on recent efforts to understand the roles and molecular mechanisms underlying autophagy, we highlight the specific roles of autophagy in plant reproduction and provide new insights for further studies.

Endosperm development is an autonomously programmed process independent of embryogenesis

The seeds of flowering plants contain three genetically distinct structures: the embryo, endosperm, and seed coat. The embryo and endosperm need to interact and exchange signals to ensure coordinated growth. Accumulating evidence has confirmed that embryo growth is supported by the nourishing endosperm and regulated by signals originating from the endosperm. Available data also support that endosperm development requires communication with the embryo. Here, using single-fertilization mutants, Arabidopsis thaliana dmp8 dmp9 and gex2, we demonstrate that in the absence of a zygote and embryo, endosperm initiation, syncytium formation, free nuclear cellularization, and endosperm degeneration occur as in the wild type in terms of the cytological process and time course. Although rapid embryo expansion accelerates endosperm breakdown, our findings strongly suggest that endosperm development is an autonomously organized process, independent of egg cell fertilization and embryo-endosperm communication. This work confirms both the altruistic and self-directed nature of the endosperm during coordinated embryo-endosperm development. Our findings provide insights into the intricate interaction between the two fertilization products and will help to distinguish the physiological roles of the signaling between endosperm and embryo. These findings also open new avenues in agro-biotechnology for crop improvement.

Fertilized egg cells secrete endopeptidases to avoid polytubey

Upon gamete fusion, animal egg cells secrete proteases from cortical granules to establish a fertilization envelope as a block to polyspermy^1-4. Fertilization in flowering plants is more complex and involves the delivery of two non-motile sperm cells by pollen tubes^5,6. Simultaneous penetration of ovules by multiple pollen tubes (polytubey) is usually avoided, thus indirectly preventing polyspermy^7,8. How plant egg cells regulate the rejection of extra tubes after successful fertilization is not known. Here we report that the aspartic endopeptidases ECS1 and ECS2 are secreted to the extracellular space from a cortical network located at the apical domain of the Arabidopsis egg cell. This reaction is triggered only after successful fertilization. ECS1 and ECS2 are exclusively expressed in the egg cell and transcripts are degraded immediately after gamete fusion. ECS1 and ESC2 specifically cleave the pollen tube attractor LURE1. As a consequence, polytubey is frequent in ecs1 ecs2 double mutants. Ectopic secretion of these endopeptidases from synergid cells led to a decrease in the levels of LURE1 and reduced the rate of pollen tube attraction. Together, these findings demonstrate that plant egg cells sense successful fertilization and elucidate a mechanism as to how a relatively fast post-fertilization block to polytubey is established by fertilization-induced degradation of attraction factors.

Epigenetic regulation and intercellular communication during male gametophyte development

The male gametophyte of angiosperms has long been recognized as an ideal system for the study of the molecular mechanisms regulating cell fate determination. Recent findings on histone variants in two cell lineages, vegetative-cell-derived small interfering RNA and transposable element expression provide new power for relevant investigations.

AtMIF1 increases seed oil content by attenuating GL2 inhibition

Vegetable oil is a major edible oil and an important industrial raw material. However, breeders have found it challenging to improve the oil content of crop seeds, and little is known about regulators with the potential to increase oil content via molecular engineering in modern oil crop breeding. We reported an F-box protein, Arabidopsis thaliana MYB Interaction Factor 1 (AtMIF1), which is a member of the ubiquitin-protein ligase E3 complex involved in the 26S proteasome protein degradation pathway. AtMIF1 physically interacts with MYB domain protein 5 (MYB5), which results in MYB5 degradation, so that transcriptional activation of the MYB/bHLH/WD-repeat (MBW) complex does not occur normally and GLABRA2 (GL2), encoding an inhibitor of oil content and functioning as a direct downstream gene of MBW, is not properly transcribed. AtMIF1 functioned as a positive regulator that increases oil content by attenuating GL2 inhibition. We overexpressed AtMIF1 and obtained transgenic plants with significantly higher seed oil contents. Importantly, both vegetative and reproductive growth of the transgenic plants appeared normal. In summary, this work reveals a novel regulator, AtMIF1, and a new regulatory pathway, 26S proteasome-AtMIF1-MYB5, for increasing the oil content of seeds without affecting plant growth, thus facilitating oil crop breeding.

ARP2/3-independent WAVE/SCAR pathway and class XI myosin control sperm nuclear migration in flowering plants

After eukaryotic fertilization, gamete nuclei migrate to fuse parental genomes in order to initiate development of the next generation. In most animals, microtubules control female and male pronuclear migration in the zygote. Flowering plants, on the other hand, have evolved actin filament (F-actin)-based sperm nuclear migration systems for karyogamy. Flowering plants have also evolved a unique double-fertilization process: two female gametophytic cells, the egg and central cells, are each fertilized by a sperm cell. The molecular and cellular mechanisms of how flowering plants utilize and control F-actin for double-fertilization events are largely unknown. Using confocal microscopy live-cell imaging with a combination of pharmacological and genetic approaches, we identified factors involved in F-actin dynamics and sperm nuclear migration in Arabidopsis thaliana (Arabidopsis) and Nicotiana tabacum (tobacco). We demonstrate that the F-actin regulator, SCAR2, but not the ARP2/3 protein complex, controls the coordinated active F-actin movement. These results imply that an ARP2/3-independent WAVE/SCAR-signaling pathway regulates F-actin dynamics in female gametophytic cells for fertilization. We also identify that the class XI myosin XI-G controls active F-actin movement in the Arabidopsis central cell. XI-G is not a simple transporter, moving cargos along F-actin, but can generate forces that control the dynamic movement of F-actin for fertilization. Our results provide insights into the mechanisms that control gamete nuclear migration and reveal regulatory pathways for dynamic F-actin movement in flowering plants.

Autophagy-mediated compartmental cytoplasmic deletion is essential for tobacco pollen germination and male fertility

In plants, macroautophagy/autophagy has mainly been associated with stress-related processes but how it impacts normal physiological and developmental processes remains largely unexplored. Pollen germination is the critical first step toward fertilization in flowering plants. It is metabolically demanding and relies on high levels of cytoplasmic reorganization activities to support a dramatic morphological transformation that underlies the development of a pollen tube as the conduit to deliver sperm for fertilization. The role of autophagy in this process remains unclear. Here we provide evidence that pollen germination is accompanied by elevated autophagic activity and successful pollen tube emergence depends on autophagy-mediated cytoplasmic deletion. Genetic and cytological experiments demonstrate that inhibition of autophagy prevents pollen germination while induces the persistence of a layer of undegraded cytoplasm at the germination aperture. Together, these results unveil a novel compartmentalized autophagy. Furthermore, high-throughput comparative lipidomic analyses show that suppressed autophagy-induced inhibition of pollen germination is accompanied by altered profiles of stored and signaling lipids. Proteomic analyses reveal that autophagy likely exert its role in pollen germination via downstream mitochondria-related pathways. These findings reveal a critical role for autophagy in initiating pollen germination and provide evidences for compartmental cytoplasmic deletion being crucial for male fertility. Abbreviations: 3-MA: 3-methyladenine; ATG: autophagy-related gene; Cer: ceramide; CL: cardiolipin; Con A: concanamycin A; DAG: diradylglycerol; GO: gene ontology; HAG: hour after germination; LC-MS: liquid chromatography-mass spectrometry; MAG: min after germination; MDC: monodansylcadaverine; PE: phosphatidylethanolamine; PI: phosphatidylinositol; PLD: phospholipase D; PtdIns3K: phosphatidylinositol 3-kinase; RT-qPCR: quantitative real-time reverse transcription PCR; TAG: triradylglycerol; TEM: transmission electron microscopy; TMT: tandem mass tagging.

Equal parental contribution to the transcriptome is not equal control of embryogenesis

In animals, early embryogenesis is maternally controlled, whereas in plants, parents contribute equally to the proembryo transcriptome. Thus, the question remains whether equivalent parental contribution to the transcriptome of the early proembryo means equal control of early embryogenesis. Here, on the basis of cell-lineage-specific and allele-specific transcriptome analysis, we reveal that paternal and maternal genomes contribute equally to the transcriptomes of both the apical cell lineage and the basal cell lineage of early proembryos. However, a strong maternal effect on basal cell lineage development was found, indicating that equal parental contribution to the transcriptome is not necessarily coupled with equivalent parental control of proembryonic development. Parental contributions to embryogenesis therefore cannot be concluded solely on the basis of the ratio of paternal/maternal transcripts. Furthermore, we demonstrate that parent-of-origin genes display developmental-stage-dependent and cell-lineage-dependent allelic expression patterns. These findings will facilitate the investigation of specific parental roles in specific processes of early embryogenesis.

Rapid Analysis of Monosaccharides in Sub-milligram Plant Samples Using Liquid Chromatography-Mass Spectrometry Assisted by Post-column Derivatization

Monosaccharides play important roles in plant growth and development, and their biofunctions are closely related to their endogenous contents. Therefore, the determination of monosaccharides is beneficial for the further study of monosaccharide biofunction. In this work, we developed a liquid chromatography-mass spectrometry analytical method assisted by a post-column derivatization technique (LC-PCD-MS) for the fast and automatic determination of 16 monosaccharides in samples. Post-column chemical derivatization of monosaccharides was performed by a reaction of monosaccharides with 4-benzylaminobenzeneboronic acid (4-PAMBA) through boronate ester formation in a three-way connector. 4-PAMBA worked as a derivatization reagent to improve the selectivity and sensitivity of monosaccharide detection by MS. The developed LC-PCD-MS method integrates LC separation, chemical derivatization, and MS detection in one run, thus greatly reducing the analysis time for each sample. The limits of detection and limits of quantification for 16 monosaccharides were in the range of 0.002-0.1 and 0.007-0.5 ng/mL, respectively. Good linearity was obtained from the linear regression, with a determination coefficient (R²) ranging from 0.9928 to 1.0000. The relative recoveries were in the range of 80.7-117.8%, with the intra- and interday relative standard deviations less than 19.7 and 16.5%, respectively, indicating good accuracy and acceptable reproducibility of the method. Finally, the method was successfully applied to investigate the spatial and temporal distribution of 16 monosaccharides in the developing flower and germinating seed of Arabidopsis thaliana.

Manual Isolation of Living Early Embryos from Tobacco Seeds

Zygotic embryogenesis is one of key processes for fertile seed development and therefore has gained great attention for decades in the field of plant developmental biology. However, this process is deeply embedded in the maternal tissues. The inaccessibility of tiny early embryos has greatly hindered the study of early embryogenesis, especially limits direct observation and accurate omics investigations. In order to investigate the molecular mechanism regulating embryo development with modern technologies, it is necessary to develop a reliable method to isolate living embryos at different stages. For this purpose, plant scientists have been trying to develop different methods for isolating zygotes and early embryos in different plants such as maize, wheat, rice, and tobacco during past decades. Nicotiana tabacum has long been considered as an ideal model eudicot for the study of embryogenesis, which displays a traceable and predictable cell division pattern, spanning from the first zygotic division to the mature embryo formation. Here, we provide a detailed protocol for isolating living embryos from zygote to cotyledon embryo. Isolated living zygotes and early embryos could be used for several important studies such as cell type-specific transcriptome construction and clear GFP observation.

[Understanding the China Blue Paper on Obesity Prevention and Control and policy implications and recommendations for obesity prevention and control in China]

With the rapid economic development and dramatic changes in lifestyle, the prevalence of overweight and obesity in China has been increasing significantly and become a serious public health threat. This article introduced the main contents of "China Blue Paper on Obesity Prevention and Control", aiming to facilitate understanding and applications of the "China Blue Paper on Obesity Prevention and Control" by policymakers, researchers and practitioners in related fields. Built upon these, recommendations were made for obesity screening, diagnosis, treatment and management, prevention and control policies and strategies, and future research priorities in China.

Maternal control of suspensor programmed cell death via gibberellin signaling

Plant embryos are generated and develop in a stable and well-protected microenvironment surrounded by maternal tissue, which is vital for embryogenesis. However, the signaling mechanisms responsible for maternal tissue-to-proembryo communication are not well understood. Here, we report a pathway for maternal tissue-to-proembryo communication. We identify a DELLA protein, NtCRF1 (NtCYS regulative factor 1), which regulates suspensor programmed cell death (PCD). NtCRF1 can bind to the promoter of NtCYS and regulate the suspensor PCD-switch module NtCYS-NtCP14 in response to gibberellin (GA). We confirm that GA4, as a primary signal triggering suspensor PCD, is generated in the micropylar endothelium by the transient activation of NtGA3oxs in the maternal tissue. Thus, we propose that GA is a maternal-to-proembryo communication signal that is decoded in the proembryo by a GID1-CRF1-CYS-CP14 signaling cascade. Using this mode of communication, maternal tissue precisely controls the embryonic suspensor PCD and is able to nurse the proembryo in a stage-dependent manner.

A VPE-like protease NtTPE8 exclusively expresses in the integumentary tapetum and is involved in seed development

Programmed cell death (PCD) is an essential process for development, and shows conserved cytological features in both plants and animals. Caspases are well-known critical components of the PCD machinery in animals. However, currently few typical counterparts have been identified in plants and only several caspase-like proteases are known to be involved in plant PCD, indicating the existence of great challenge for confirming new caspase-like proteases and elucidating the mechanisms regulating plant PCD. Here, we report a novel cysteine protease, NtTPE8, which was extracted from tobacco seeds and confirmed as a new caspase-like protease. Recombinant NtTPE8 exhibited legumain and caspase-like proteolytic activities, both of which could be inhibited by the pan-caspase inhibitor (Z-VAD-FMK). Notably, NtTPE8 possessed several caspase activities and the capacity to cleave the cathepsin H substrate FVR, indicating a unique character of NtTPE8. NtTPE8 was exclusively expressed in the integumentary tapetum and thus, is the first specific molecular marker reported to date for this cell type. Down-regulation of NtTPE8 caused seed abortion, via disturbing early embryogenesis, indicating its critical role in embryogenesis and seed development. In conclusion, we identified a novel caspase-like cysteine protease, NtTPE8, exclusively expressed in the integumentary tapetum that is involved in seed development.

[Analysis of body composition and resting metabolic rate of 858 middle-aged and elderly people in urban area of Beijing]

Objective: To understand the overweight rate and obesity rate in middle-aged and elderly people in urban area of Beijing, and analyze the changes of body composition and resting metabolic rate with age. Methods: From November 2014 to December 2015, body composition measurement and resting metabolic rate detection were conducted among 858 people aged 51 to 99 years, including 760 men, 98 women, who received physical examination at Beijing Hospital. Results: The overweight rate was 51.4%, and the obesity rate was 16.9%. The overweight rate was 26.5% and the obesity rate was 14.3% in women, significantly lower than those in men (54.6% and 17.2%) (P<0.001). The distribution of skeletal muscle volume, muscle index, body fat percentage, visceral fat area and resting metabolic rate in different age groups were different (P<0.001). In the normal weight group, the skeletal muscle volume, muscle index and resting metabolic rate in age group ≥80 years decreased obviously (P<0.05). At the same time, the body fat percentage and visceral fat area increased obviously (P<0.05). However, the skeletal muscle volume, muscle index and resting metabolic rate of the overweight and obese groups began to decrease obviously in age group 70- years (P<0.05), and the decrease in age group ≥80 years was more obvious. At the same time, body fat percentage and visceral fat area increased significantly in age group 70- years (P<0.05). Conclusion: The overweight and obesity rates were high in the middle-aged and elderly people in the urban area of Beijing, and the rates were higher in men than in women. With the increase of age, the skeletal muscle volume, muscle index and resting metabolic rate gradually decreased, while the percentage of body fat and visceral fat area increased; Overweight and obese people had earlier changes in body composition and resting metabolic rate.

[Schwannoma of the ethmoid sinus in children: a case report]

A ten years old male patient，the main symptom was prsented as the left nasal obstruction, repeated hemorrhage with hyposmia. Large translucent neoplasm can be seen in the left side of the nasal cavity. CT and MRI of the nasal sinus showed that the soft tissue density shadow in the left side of the ethmoid sinus and the surrounding bone with no damage. He was treated with nasal endoscopic surgery. Postoperative pathology showed schwannoma. The tumor recurred three years later, and the patient underwent nasal endoscopic surgery again. In the literature we reviewed the case to analyze the reasons of recurrence.

Papain-like and legumain-like proteases in rice: genome-wide identification, comprehensive gene feature characterization and expression analysis

BACKGROUND

Papain-like and legumain-like proteases are proteolytic enzymes which play key roles in plant development, senescence and defense. The activities of proteases in both families could be inhibited by a group of small proteins called cystatin. Cystatin family genes have been well characterized both in tobacco and rice, suggesting their potential roles in seed development. However, their potential targets, papain-like and legumain-like proteases, have not been well characterized in plants, especially in rice, a model plant for cereal biology.

RESULTS

Here, 33 papain-like and 5 legumain-like proteases have been identified in rice genome, respectively. Gene structure, distribution in rice chromosome, and evolutionary relationship to their counterparts in other plants have been well characterized. Comprehensive expression profile analysis revealed that two family genes display divergent expression pattern, which are regulated temporally and spatially during the process of seed development and germination. Our experiments also revealed that the expression of most genes in these two families is sensitively responsive to plant hormones and different abiotic stresses.

CONCLUSIONS

Genome-wide identification and comprehensive gene expression pattern analysis of papain-like and legumain-like proteases in rice suggests their multiple and cooperative roles in seed development and response to environmental variations, which provides several useful cues for further in-depth study.

The stereotyped positioning of the generative cell associated with vacuole dynamics is not required for male gametogenesis in rice pollen

During male gametogenesis in cereals, the generative cell undergoes a positioning process that parallels the dynamics of the central vacuole, which is believed to be associated with generative cell movement in the male gametophyte. However, the impact of the generative cell positioning and the central vacuole dynamics on male gametogenesis has remained poorly understood. Here, we report that OsGCD1 (GAMETE CELLS DEFECTIVE1) dysfunction influenced pollen development and disrupted pollen germination. Loss of function of OsGCD1 altered the central vacuole dynamics and the generative cell was mispositioned. Nevertheless, twin sperm cells were generated normally, indicating that gametogenesis does not rely on positional information as long as a generative cell is produced. The normal vacuole dynamics seems necessary only for pollen maturation and germination. Our findings also indicate that osgcd1 mutation resulted in rice male sterility in which pollen has full cell viability and generated normal gametes, but lacks the potential to germinate.

The suspensor as a model system to study the mechanism of cell fate specification during early embryogenesis

The advances in the suspensor. During early embryogenesis, the proembryo consists of two domains, the embryo proper and the suspensor. Unlike the embryo proper, which has been investigated extensively, research on the suspensor has been limited in past decades. Recent studies have revealed that the suspensor plays an important role in early embryogenesis and the process of suspensor formation and degeneration may provide a unique model for studies on cell division pattern, cell fate determination, and cell death. In this review, we briefly summarize the advances in research on the suspensor, which provide new insight in our understanding of the mechanism of early embryogenesis and show great potential for a unique model for future investigations.

Ribosomal protein NtRPL17 interacts with kinesin-12 family protein NtKRP and functions in the regulation of embryo/seed size and radicle growth

We previously reported that a novel motor protein belonging to the kinesin-12 family, NtKRP, displays critical roles in regulating embryo and seed size establishment. However, it remains unknown exactly how NtKRP contributes to this developmental process. Here, we report that a 60S ribosomal protein NtRPL17 directly interacts with NtKRP. The phenotypes of NtRPL17 RNAi lines show notable embryo and seed size reduction. Structural observations of the NtRPL17-silenced embryos/seeds reveal that the embryo size reduction is due to a decrease in cell number. In these embryos, cell division cycle progression is delayed at the G2/M transition. These phenotypes are similar to that in NtKRP-silenced embryos/seeds, indicating that NtKRP and NtRPL17 function as partners in the same regulatory pathway during seed development and specifically regulate cell cycle progression to control embryo/seed size. This work reveals that NtRPL17, as a widely distributed ribosomal protein, plays a critical role in seed development and provides a new clue in the regulation of seed size. Confirmation of the interaction between NtKRP and NtRPL17 and their co-function in the control of the cell cycle also suggests that the mechanism might be conserved in both plants and animals.

The autonomous cell fate specification of basal cell lineage: the initial round of cell fate specification occurs at the two-celled proembryo stage

In angiosperms, the first zygotic division usually gives rise to two daughter cells with distinct morphologies and developmental fates, which is critical for embryo pattern formation; however, it is still unclear when and how these distinct cell fates are specified, and whether the cell specification is related to cytoplasmic localization or polarity. Here, we demonstrated that when isolated from both maternal tissues and the apical cell, a single basal cell could only develop into a typical suspensor, but never into an embryo in vitro. Morphological, cytological and gene expression analyses confirmed that the resulting suspensor in vitro is highly similar to its undisturbed in vivo counterpart. We also demonstrated that the isolated apical cell could develop into a small globular embryo, both in vivo and in vitro, after artificial dysfunction of the basal cell; however, these growing apical cell lineages could never generate a new suspensor. These findings suggest that the initial round of cell fate specification occurs at the two-celled proembryo stage, and that the basal cell lineage is autonomously specified towards the suspensor, implying a polar distribution of cytoplasmic contents in the zygote. The cell fate transition of the basal cell lineage to the embryo in vivo is actually a conditional cell specification process, depending on the developmental signals from both the apical cell lineage and maternal tissues connected to the basal cell lineage.

[Analysis of early response to the antipsychotic treatment and related factors in acute schizophrenia patients]

Objective: The objective was to assess the relationship between early response and later response to antipsychotics, and the relationship between antipsychotics and early response. Methods: Data were retrospectively analyzed from patients with schizophrenia and they were hospitalized in the Second Affiliated Hospital of Xinxiang Medical College from May, 2013 to September, 2015.The patients were divided into theearly response group (PANSS total score improvement ≥20% at week 2) and early nonresponse group.General information, the use of drug and the Positive and Negative Syndrome Scale (PANSS) on before and 2, 4, 6 weeks after treatment were compared between the two groups.The relation between early response and late response and the effect of drug selection on early response were analyzed by correlation analysis and regression analysis. Results: Relative to early nonresponders, early responders were significantly more likely to have lower PANSS scores (total scores on 2, 4, 6 weeks after treatment 66.2±11.8 vs 84.5±10.9, 55.9±13.2 vs 70.9±13.7, 48.9±13.1 vs 60.6±14.9, all P<0.05) and higher PANSS scores improvement at 2, 4, 6 weeks after treatment (total scores improvement on 2, 4, 6 weeks after treatment (37±14)% vs (9±7)%, (56±19)% vs (32±18)%, (68±20)% vs (49±21)%, all P<0.05). The correlation coefficient between PANSS total score improvement at week 2 and at week 4, 6 were 0.730 and 0.541, respectively (all P<0.05). Olanzapine had more PANSS total score improvement than aripiprazole, quetiapine and ziprasidone (2 weeks after treatment (29±19)% vs (19±16)%, (18±15)%, (17±15)%, 4 weeks after treatment (51±21)% vs (37±25)%, (39±18)%, (37±22)%, all P<0.05). The protective factor for early response was olanzapine (P<0.05). Conclusions: Early responders are associated with faster and greater improvement in symptoms, the type of antipsychotic has impacts on early response, early non-responders can benefit from adjustment of treatment.

OsGCD1 is essential for rice fertility and required for embryo dorsal-ventral pattern formation and endosperm development

Rice fertility is critical for rice reproduction and is thus a focus of interest. Most studies have addressed male sterility and its relation to rice production. The mechanisms of regulation of embryogenesis and endosperm development are essential for rice reproduction, but remain largely unknown. Here, we report a functional analysis of the rice gene OsGCD1, which encodes a highly conserved homolog of Arabidopsis GCD1 (GAMETE CELLS DEFECTIVE1). OsGCD1 mutants were generated using the CRISPR/Cas9 system and subjected to functional analysis. The homozygote mutants cannot be obtained, whereas heterozygotes showed altered phenotypes. In the majority of aborted seeds, the endosperm nucleus divided a limited number of times. The free nuclei were distributed only at the micropylar end of embryo sacs, and their oriented positioning was blocked. In addition, aleurone differentiation was interrupted. The embryo developed slowly, and pattern formation, particularly the dorsal-ventral pattern and symmetry establishment, of embryos was disturbed. Thus, the embryos showed various morphological and structural dysplasias. Our findings reveal that OsGCD1 is essential for rice fertility and is required for dorsal-ventral pattern formation and endosperm free nucleus positioning, suggesting a critical role in sexual reproduction of both monocotyledon and dicotyledon plants.

Identification of genes related to floral organ development in pak choi by expression profiling

Pak choi is a highly nutritious vegetable that is widely grown in China, Southeast Asia, and other parts of the world. Because it reproduces by seed, it is very important to understand the mechanism of floral organ development. Therefore, using the Chinese cabbage genome as a reference, this study analyzed the expression profiles of shoot apex genes at flower bud differentiation stages 1 and 5, in order to identify genes related to floral organ development. The results showed that the proportion of mapped genes was high, with 84.25 and 83.80% of clean reads from the two sample saligned to the reference genome, respectively. A total of 525 differentially expressed genes (DEGs) were identified, 224 of which were upregulated and 301 were downregulated. The expression levels of genes homologous to Chinese cabbage flowering genes were also analyzed at stages 1 and 5; the expression levels of Bra012997 (ap1), Bra000393 (SOC1), and Bra004928 (SOC1) were significantly upregulated at stage 5, suggesting that these three genes positively regulate floral development in pak choi. DEGs involved in floral organ development were analyzed with homologous genes from Arabidopsis thaliana; the homologous genes Bra029281 (AGL42), Bra026577 (ARPN), Bra022954 (SPL3), Bra029293 (ARF2), Bra007978 (AtRLP12), Bra033221 (SPL8), Bra008037 (LOX4), Bra001598 (IAA19), Bra003892 (PATL1), Bra038778 (AT4G21323), Bra025315 (KLCR2), and Bra013906 (DTX35) are directly related to floral organ development in Arabidopsis, suggesting that these genes have corresponding functions during flower organ development in pak choi, and could be candidates for further genetic research. These results provide a foundation for research on the molecular mechanism of flower organ development in pak choi and other Brassica rapa vegetables.

Does Early Embryogenesis in Eudicots and Monocots Involve the Same Mechanism and Molecular Players?

A comparison of eudicot and monocot model plants explores recent advances and open questions on gene regulatory networks during zygote development, parental influences on early embryogenesis, zygotic genome activation, and cell fate determination.

NtDRP is necessary for accurate zygotic division orientation and differentiation of basal cell lineage toward suspensor formation

Plant embryogenesis begins with an asymmetric division of the zygote, producing apical and basal cells with distinct cell fates. The asymmetric zygote division is thought to be critical for embryo pattern formation; however, the molecular mechanisms regulating this process, especially maintaining the accurate position and proper orientation of cell division plane, remain poorly understood. Here, we report that a dynamin-related protein in Nicotiana tabacum, NtDRP, plays a critical role in maintaining orientation of zygotic division plane. Down-regulation of NtDRP caused zygotic cell division to occur in different, incorrect orientations and resulted in disruption of suspensor formation, and even development of twin embryos. The basal cell lineage totally integrated with the apical cell lineage into an embryo-like structure, suggesting that NtDRP is essential to accurate zygotic division orientation and differentiation of basal cell lineage toward suspensor formation. We also reveal that NtDRP plays its role by modulating microtubule spatial organization and spindle orientation during early embryogenesis. Thus, we revealed that NtDRP is involved in orientation of the asymmetric zygotic division and differentiation of distinct suspensor and embryo domains, as well as subsequent embryo pattern formation.

NtKRP, a kinesin-12 protein, regulates embryo/seed size and seed germination via involving in cell cycle progression at the G2/M transition

Kinesins comprise a superfamily of microtubule-based motor proteins involved in essential processes in plant development, but few kinesins have been functionally identified during seed development. Especially, few kinesins that regulate cell division during embryogenesis have been identified. Here we report the functional characterization of NtKRP, a motor protein of the kinesin-12 family. NtKRP is predominantly expressed in embryos and embryonic roots. NtKRP RNAi lines displayed reductions in cell numbers in the meristematic zone, in embryonic root length, and in mature embryo and seed sizes. Furthermore, we also show that CDKA;1 binds to NtKRP at the consensus phosphorylation sites and that the decreased cell numbers in NtKRP-silenced embryos are due to a delay in cell division cycle at the G2/M transition. In addition, binding between the cargo-binding tail domain of NtKRP and CDKA; 1 was also determined. Our results reveal a novel molecular pathway that regulates embryo/seed development and critical role of kinesin in temporal and spatial regulation of a specific issue of embryo developmental.

Asymmetric zygote division: A mystery starting point of embryogenesis

In angiosperm, asymmetric zygote division is critical for embryogenesis. The molecular mechanism underlying this process has gained a great attention recently. Some players involve in the control of both accurate position and correct orientation of zygote division plane have been found, which provide useful clues for the extensive investigations. It is getting clear that both internal and external factors are involved in this complex regulatory mechanism and the asymmetric zygote division seems with great impact in cell fate determination and embryo pattern formation.

Autophagy in sexual plant reproduction as an emerging field

Autophagy is an evolutionary conserved system for clearing and recycling cellular components. Critical roles of autophagy in the responses of plant to different environmental stresses have been revealed during past decades. However, little is known about the role of autophagy in plant developmental processes, especially in the processes of sexual plant reproduction. Here, we briefly discuss recent advances in the emerging field and wish to bring some potential research directions into attention. Possible divergence of molecular mechanism of autophagy in respect to the current debatable view is also discussed.

Initiation of programmed cell death in the suspensor is predominantly regulated maternally in a tobacco hybrid

Maternal gene products deposited in the egg regulate early embryogenesis before activation of the embryonic genome in animals. While in higher plants, it is believed that genes of parental origin contribute to early embryogenesis. However, little is known regarding the particular processes in which genes of parental origin are involved during early embryogenesis. Previously, we found that the initiation of programmed cell death (PCD) in the suspensor of the embryo is regulated by the cystatin, NtCYS. Here, we confirmed that both parental transcripts contribute to PCD, but the relative expression level of the maternal NtCYS allele was much higher than that of the paternal allele in early embryos of tobacco interspecific hybrids. The expression level of the maternal NtCYS allele was decreased markedly, which was necessary for the initiation of PCD, while the paternal allele didn't change. Interestingly, the pattern of PCD in the hybrid suspensor and the morphology of the hybrid suspensor were similar to those of the maternal parent. Our results suggest that NtCYS-mediated PCD initiation in the hybrid suspensor is likely controlled in a maternal dominant manner. This finding represents an example of the involvement of parental transcripts in a specific developmental event during early embryogenesis.

Detection and study of plasma D-dimer change in patients with acute exacerbation of chronic obstructive pulmonary disease

The purpose of this study was to observe the change in plasma D-dimer of patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). The patients were divided into three groups, i.e., AECOPD group, stable COPD group (COPD kept stable after treatment) and a healthy control group. The content of plasma fibrinogen (FIB) and D-dimer of all research subjects was detected and the difference between groups was analyzed. Moreover, pulmonary functions of patients in the AECOPD group and the stable COPD group, including forced expiratory volume in 1 second (FEV1%) and forced vital capacity rate of 1 second (FEV1/FVC), and blood gas (oxygen partial pressure (PO₂) and partial pressure of carbon dioxide (PaCO₂), were detected; and the differences between the two groups and the possible correlation were analyzed. Compared to the COPD stable group and the control group, the AECOPD group had a statistically significant higher content of plasma FIB and D-dimer (p less than 0.05); the content of plasma FIB and D-dimer of the COPD stable group was much higher than that of the healthy control group, but the difference had no statistical significance (p > 0.05); the content of D-dimer of AECOPD patients was in a negative correlation with FEV1 and PO₂ (p smaller than 0.05) and in a positive correlation with PCO₂ (p smaller than 0.05). It can be concluded that D-dimer is correlated to the severity of AECOPD; hence, it can be used as an evaluation index for the severity of AECOPD.

Direct evidence that suspensor cells have embryogenic potential that is suppressed by the embryo proper during normal embryogenesis

The suspensor is a temporary supporting structure of proembryos. It has been proposed that suspensor cells also possess embryogenic potential, which is suppressed by the embryo as an effect of the embryo-suspensor interaction. However, data to support this hypothesis are not yet available. In this report, using an in vivo living cell laser ablation technique, we show that Arabidopsis suspensor cells can develop into embryos after removing the embryo proper. The embryo proper plays a critical role in maintaining suspensor cell identity. However, this depends on the developmental stage; after the globular embryo stage, the suspensors no longer possess the potential to develop into embryos. We also reveal that hypophysis formation may be essential for embryo differentiation. Furthermore, we show that, after removing the embryo, auxin gradually accumulates in the top suspensor cell where cell division occurs to produce an embryo. Auxin redistribution likely reprograms the fate of the suspensor cell and triggers embryogenesis in suspensor cells. Thus, we provide direct evidence that the embryo suppresses the embryogenic potential of suspensor cells.

Genome-wide identification and characterization of cystatin family genes in rice (Oryza sativa L.)

11 Cystatin genes in rice were identified, and their expression patterns were comprehensively analyzed, which reveals multiple roles in both seed development and plant response to environmental variations. Cystatin is a group of small proteins and known to inhibit the activities of cysteine proteases in the papain C1A and legumain C13 peptidase families in plants. Cystatin family genes have only been well characterized recently in a few plant species such as Hordeum vulgare and Nicotiana tabacum, which show their critical roles in programmed cell death and responses to biotic stresses. Up to now, little is known about cystatin family genes and their roles in Oryza sativa, a model plant for cereal biology study. Here, we identified 11 cystatin genes in rice genome. Comprehensive expression profile analysis reveals that cystatin family genes in rice display diverse expression pattern. They are temporally regulated at different developmental stages during the process of seed production and germination. Our experiments also reveal that the majority of cystatin genes are responsive to plant hormones and different environmental cues including cold, drought and other abiotic stresses, while some others are very stable under different stresses, indicating their fundamental roles in normal plant development. In addition, their distribution in rice chromosomes and their evolutionary relation to the members of Cystatin family in A. thaliana and N. tabacum have also been analyzed. These works suggest multiple roles of cystatin family genes in both seed development and plant response to environmental variations.

The Maternal-to-Zygotic Transition in Higher Plants: Available Approaches, Critical Limitations, and Technical Requirements

Fertilization marks the turnover from the gametophyte to sporophyte generation in higher plants. After fertilization, sporophytic development undergoes genetic turnover from maternal to zygotic control: the maternal-to-zygotic transition (MZT). The MZT is thought to be critical for early embryogenesis; however, little is known about the time course or developmental impact of the MZT in higher plants. Here, we discuss what is known in the field and focus on techniques used in relevant studies and their limitations. Some significant questions and technical requirements for further investigations are also discussed.

Phytosulfokine peptide signaling controls pollen tube growth and funicular pollen tube guidance in Arabidopsis thaliana

Phytosulfokine (PSK) is a peptide growth factor that requires tyrosine sulfation carried out by tyrosylprotein sulfotransferase (TPST) for its activity. PSK is processed from precursor proteins encoded by five genes in Arabidopsis thaliana and perceived by receptor kinases encoded by two genes in Arabidopsis. pskr1-3 pskr2-1 and tpst-1 knockout mutants displayed reduced seed production, indicative of a requirement for PSK peptide signaling in sexual plant reproduction. Expression analysis revealed PSK precursor and PSK receptor gene activity in reproductive organs with strong expression of PSK2 in pollen. In support of a role for PSK signaling in pollen, in vitro pollen tube (PT) growth was enhanced by exogenously added PSK while PTs of pskr1-3 pskr2-1 and of tpst-1 were shorter. In planta, growth of wild-type pollen in pskr1-3 pskr2-1 and tpst-1 flowers appeared slower than growth in wild-type flowers. But PTs did eventually reach the base of the style, suggesting that PT elongation rate may not be responsible for the reduced fertility. Detailed analysis of anthers, style and ovules did not reveal obvious developmental defects. By contrast, a high percentage of unfertilized ovules in pskr1-3 pskr2-1 and in tpst-1 siliques displayed loss of funicular PT guidance, suggesting that PSK signaling is required to guide the PT from the transmitting tract to the embryo sac. Cross-pollination experiments with wild-type, pskr1-3 pskr2-1 and tpst-1 male and female parents revealed that both the PT and the female sporophytic tissue and/or female gametophyte contribute to successful PT guidance via PSK signaling and to fertilization success.

Characteristics and viral propagation properties of a new human diploid cell line, Walvax-2, and its suitability as a candidate cell substrate for vaccine production

Human diploid cell strains (HDCSs), possessing identical chromosome sets known to be free of all known adventitious agents, are of great use in developing human vaccines. However it is extremely difficult to obtain qualified HDCSs that can satisfy the requirements for the mass production of vaccines. We have developed a new HDCS, Walvax-2, which we derived from the lung tissue of a 3-month-old fetus. We established primary, master and working cell banks successfully from reconstituted frozen cells. Observations during the concurrent propagation of Walvax-2 and MRC-5 cells revealed differences in terms of growth rate, cell viability and viral sensitivities. Specifically, Walvax-2 cells replicated more rapidly than MRC-5 cells, with Walvax-2 cells attaining the same degree of confluence in 48 hours as was reached by MRC-5 cells in 72 hours. Moreover, Walvax-2 cells attained 58 passages of cell doublings whereas MRC-5 reached 48 passages during this period. We also assessed the susceptibility of these cells to rabies, hepatitis A, and Varicella viruses. Analysis of virus titers showed the Walvax-2 cells to be equal or superior to MRC-5 cells for cultivating these viruses. Furthermore, in order to characterize the Walvax-2 cell banks, a series of tests including cell identification, chromosomal characterization, tumorigenicity, as well as tests for the presence of microbial agents, exogenous viruses, and retroviruses, were conducted according to standard international protocols. In conclusion, results from this study show that Walvax-2 cell banks are a promising cell substrate and could potentially be used for the manufacturing of HDCVs.

Exogenous γ-aminobutyric acid (GABA) affects pollen tube growth via modulating putative Ca2+-permeable membrane channels and is coupled to negative regulation on glutamate decarboxylase

γ-Aminobutyric acid (GABA) is implicated in pollen tube growth, but the molecular and cellular mechanisms that it mediates are largely unknown. Here, it is shown that exogenous GABA modulates putative Ca(2+)-permeable channels on the plasma membranes of tobacco pollen grains and pollen tubes. Whole-cell voltage-clamp experiments and non-invasive micromeasurement technology (NMT) revealed that the influx of Ca(2+) increases in pollen tubes in response to exogenous GABA. It is also demonstrated that glutamate decarboxylase (GAD), the rate-limiting enzyme of GABA biosynthesis, is involved in feedback controls of Ca(2+)-permeable channels to fluctuate intracellular GABA levels and thus modulate pollen tube growth. The findings suggest that GAD activity linked with Ca(2+)-permeable channels relays an extracellular GABA signal and integrates multiple signal pathways to modulate tobacco pollen tube growth. Thus, the data explain how GABA mediates the communication between the style and the growing pollen tubes.

Inducible knock-down of GNOM during root formation reveals tissue-specific response to auxin transport and its modulation of local auxin biosynthesis

In plants, active transport of auxin plays an essential role in root development. Localization of the PIN1 auxin transporters to the basal membrane of cells directs auxin flow and depends on the trafficking mediator GNOM. GNOM-dependent auxin transport is vital for root development and thus offers a useful tool for the investigation of a possible tissue-specific response to dynamic auxin transport. To avoid pleiotropic effects, DEX-inducible expression of GNOM antisense RNA was used to disrupt GNOM expression transiently or persistently during embryonic root development. It was found that the elongation zone and the pericycle layer are the most sensitive to GNOM-dependent auxin transport variations, which is shown by the phenotypes in cell elongation and the initiation of lateral root primordia, respectively. This suggests that auxin dynamics is critical to cell differentiation and cell fate transition, but not to cell division. The results also reveal that GNOM-dependent auxin transport could affect local auxin biosynthesis. This suggests that local auxin biosynthesis may also contribute to the establishment of GNOM-dependent auxin gradients in specific tissues, and that auxin transport and local auxin biosynthesis may function together in the regulatory network for initiation and development of lateral root primordia. Thus, the data reveal a tissue-specific response to auxin transport and modulation of local auxin biosynthesis by auxin transport.