Plant-on-chip: Core morphogenesis processes in the tiny plant Wolffia australiana

A plant can be thought of as a colony comprising numerous growth buds, each developing to its own rhythm. Such lack of synchrony impedes efforts to describe core principles of plant morphogenesis, dissect the underlying mechanisms, and identify regulators. Here, we use the minimalist known angiosperm to overcome this challenge and provide a model system for plant morphogenesis. We present a detailed morphological description of the monocot Wolffia australiana, as well as high-quality genome information. Further, we developed the plant-on-chip culture system and demonstrate the application of advanced technologies such as single-nucleus RNA-sequencing, protein structure prediction, and gene editing. We provide proof-of-concept examples that illustrate how W. australiana can decipher the core regulatory mechanisms of plant morphogenesis.

Single-cell RNA sequencing reveals abnormal fluctuations in human eight-cell embryos associated with blastocyst formation failure

Infertility has become a global health issue, with the number of people suffering from the disease increasing year by year, and ART offering great promise for infertility treatment. However, the regulation of early embryonic development is complicated and a series of processes takes place, including the maternal-to-zygotic transition. In addition, developmental arrest is frequently observed during human early embryonic development. In this study, we performed single-cell RNA sequencing on a biopsied blastomere from human eight-cell embryos and tracked the developmental potential of the remaining cells. To compare the sequencing results between different eight-cell embryos, we have combined the research data of this project with the data previously shared in the database and found that cells from the same embryo showed a higher correlation. Additionally, the transcriptome of embryos with blastocyst formation failure was significantly different from developed embryos, and the gene expression as well as cell signaling pathways related to embryonic development were also altered. In particular, the expression of some maternal and zygotic genes in the failed blastocyst formation group was significantly altered: the overall expression level of maternal genes was significantly higher in the failed blastocyst than the developed blastocyst group. In general, these findings provide clues for the causes of human embryonic arrest after the eight-cell stage, and they also provide new ideas for improving the success rate of ART in clinical practice.

Single-cell analyses identify distinct and intermediate states of zebrafish pancreatic islet development

Pancreatic endocrine islets are vital for glucose homeostasis. However, the islet developmental trajectory and its regulatory network are not well understood. To define the features of these specification and differentiation processes, we isolated individual islet cells from TgBAC(neurod1:EGFP) transgenic zebrafish and analyzed islet developmental dynamics across four different embryonic stages using a single-cell RNA-seq strategy. We identified proliferative endocrine progenitors, which could be further categorized by different cell cycle phases with the G1/S subpopulation displaying a distinct differentiation potential. We identified endocrine precursors, a heterogeneous intermediate-state population consisting of lineage-primed alpha, beta and delta cells that were characterized by the expression of lineage-specific transcription factors and relatively low expression of terminally differentiation markers. The terminally differentiated alpha, beta, and delta cells displayed stage-dependent differentiation states, which were related to their functional maturation. Our data unveiled distinct states, events and molecular features during the islet developmental transition, and provided resources to comprehensively understand the lineage hierarchy of islet development at the single-cell level.

Stable Suppression of Gene Expression in Murine Embryonic Stem Cells by RNAi Directed from DNA Vector-Based Short Hairpin RNA

Murine embryonic stem (ES) cells are an ideal system for the research of directed differentiation in vitro. Long double-stranded RNA, which can induce RNA interference (RNAi) effectively in many organisms, has been shown to suppress target gene expression efficiently and specifically in undifferentiated ES cells. However, it cannot be used in differentiated ES cells due to unspecific inhibition of gene expression resulting from the activation of interferon pathway following differentiation. Using green fluorescent protein (GFP) as a reporter system, we show here that a short hairpin RNA (shRNA) expression vector driven by the murine U6 small nuclear RNA promoter can specifically induce potent gene knockdown effect (i.e., inhibit GFP expression specifically) when transfected transiently into ES cells. Furthermore, when the expression vector is stably integrated into the genome of the cell, it can still show specific RNAi effect, which can be maintained at least for 10 days. These transfected ES cells showed no obvious differences in the morphology or growth rate in culture compared with untransfected cells, suggesting that the activation of shRNA-directed RNAi did not affect the properties of ES cells and that the RNAi effect in ES cells is specific and persistent. Our results prove the feasibility of the U6 promoter-driven shRNA expression technique to be used to study the function of genes expressed in ES cells. These ES cells, after integration of the U6-based RNAi vector into their genome, could be used to generate gene knockdown mice.

Comparison of the method establishing embryonic stem cell lines from five different mouse strains

We compared the characteristics of the method establishing embryonic stem cell lines from five different mouse strains using the medium containing 70% rat heart cell-conditioned medium (RH-CM) as ES cell culture medium, using the primary murine embryo fibroblast as feeder cells, and using the digestive enzyme buffer containing 1% chicken serum and "the series digestive method". We first reported new ES cell lines established from the outbred strain mice KM and ICR using the improved method in our lab and the ratio of establishment of ES cell lines from KM and ICR strain mice is up to 12% and 42.1% respectively. Compared with routine method of establishing ES cell lines, the improved method made distinct differences, increasing the ratio of ES cell line's establishment of 129/ter mouse from 11.8% to 33.3%, that of C57BL/6J mouse from 3.7% to 13.3%, that of BALB/c mouse from 2.9% to 19.4%. We tested the appropriate dispersing occasion, that is proliferating period of the ICM, affected the formation of ES clones and the ratios of ES cell lines established. It was shown that the most appropriate dispersed occasion for the ICM of 129/ter, C57BL/6J, BALB/c, KM and ICR mice was 4-6 d, 3-3.5 d, 4 d, 4-5 d, 4-5 d after ICM proliferation respectively. At the same time, the effects of the concentration of digestive enzyme buffer were discussed. It was found that the ES cells from BALB/c mice were sensitive to the high concentration of digestive enzyme buffer and the 0.05% Trypsin-0.008% EDTA is an ideal concentration for their establishment and maintenance. It was shown that 'the series dispersed method' was much better than 'the once dispersed method' on the aspect of dispersing the proliferating ICM and formation of ES clones. Compared with the routine ES cell culture medium containing mLIF, the RH-CM not only remarkably inhibited the differentiation of murine ES cells and maintained their diploid karyotype, but also promoted the attachment and growth of ES cells. This improved method of establishment and culture of ES cell lines effectively maintained a series of their characteristics of pluripotent embryonic stem cells.

[RNA interference directed by small hairpin RNA expressed in COS-7 cells]

RNA interference is a phenomenon of gene silencing directed by double-stranded RNA. It can specifically inhibit gene expression by degrading mRNA efficiently and has been widely used to knockdown gene expression in Caenorhabditis elegans, Drosophila melanogaster, etc. For mammalian cells, dsRNA directed RNAi was detected only in murine undifferentiated ES or embryonic carcinoma (EC) cells. Our previous work proved the existence of RNAi effect for reporter gene GFP and endogenous gene Oct4 in undifferentiated murine ES cells. Yet in other kinds of mammalian cells, because of the existence of interferon pathway, long dsRNA will induce the cells to shutdown global protein translation and go to apoptosis. Therefore, dsRNA longer than 30 bp cannot be used to induce specific gene knockdown effect in these cells. Elbashir et al found that in vitro synthesized small interfering RNA (siRNA) (19-23 nt) could induce potent RNAi as effective as long dsRNA without showing unspecific effect, so that the interferon pathway could be bypassed. It was shown that during RNAi process, long dsRNA was first degraded into 19-23 nt siRNA and then recruited into RISC (RNA induced silencing complex) to degrade corresponding mRNA. However, the synthesis of siRNA is expensive and the effect is transient because the knockdown effect can only be maintained for about a week. Recently, it has been shown that U6 promoter directed small hairpin RNA (shRNA) can induce potent gene knockdown effect in murine P19 Embryonic Carcinoma cell. The RNAi effect of U6 promoter-driven shRNA corresponding to Green Fluorescence Protein (GFP) in COS-7 cells was checked. And it was found that the U6 promoter-driven shRNA for GFP can specifically and potently knockdown the GFP's expression in COS-7 cells. The result established the feasibility of using RNAi technique directed by U6 promoter-driven shRNA to study genes' function in COS-7 cell line.

[RNA interference in three ES cell lines from different mouse strains]

RNA interference phenomenon in three different murine ES cell lines (MESPU13, B3, and R1) is reported. A vector(pdsGFP) was used that transcribed hairpin double-stranded RNA of GFP gene to transfect ES cells by using lipofectin. The transient transcription of dsRNA induced RNAi (RNA interference) in the ES cells. That is, the double-stranded RNA of GFP gene potently turned down the expression of the GFP gene. On the hand, the linearized plasmid pdsGFP-puro was electroporated into MESPU13 ES cells, and the expression level of GFP after puromycin screening was turned down obviously in about 30% ES cell clones; and in a few clones, the expression level of GFP was not observed under the fluorescence microscope and GFP mRNA was not detectable by RT-PCR. Further more, another vector (pdsOCT4) was constructed that transcribed double-stranded RNA of OCT-4 gene which is specifically expressed in ES cells. ES cell clones that stably integrated the vector were screened after the electrotransfection of the cells with the above construct. 51 random-selected clones were amplified and 48 of them were checked by semi-quantitative RT-PCR. In 11 of them the mRNA of OCT-4 was undetectable by RT-PCR. This means that RNAi can be used to study mammal and human gene's function in ES cell lines from different strain mice.

[Discussion of the methods for establishing embryonic stem cell lines from 129/ter. C57BL/6J mice with high efficiency]

A new method for establishing ES cell lines from 129/ter. C57BL/6J mice was set up which was characterized by the murine embryonic fibroblast cell(MEF) feeder, the medium of rat heart cell-conditioned medium(RH-CM) for ES cells, and the consecutive digestion by the digestion liquid containing 1% serum. Every group of improved experiments was done with a control of routine method. The results showed that, compared with routine method, the improved way increased the ratio of ES cell lines of 129/ter mice from 11.8% to 33.3%, and of C57BL/6J from 3.7% to 13.3%. The difference is distinct. The passage culture of ES cells showed that, compared with medium added LIF, RH-CM not only inhibited the differentiation of murine ES cells, maintained its dipoild karyotype, but also promote its adherence growth. This kind of culture condition not only maintained the ES cells in an undifferentiated state and their normal dipoild karyotype, but also a series of other characteristics of totipotent embryonic stem cells during extended culture period.

An epidemiologic study of dog bites among postmen in central Taiwan

BACKGROUND

The purpose of this study was to investigate the occupational hazard of dog bites among postmen.

METHODS

Data were collected from postmen working for 9 post offices in central Taiwan using the postmen's 1994 annual health examinations. Of 237 eligible postmen, 192 postmen (81.0%), including 183 men and 9 women, participated in this study. Detailed personal and occupational information and experiences of dog bites during a 3-year period (1991 to 1994) were obtained through a structured questionnaire. Baseline variables and occupational data were examined as risk factors for the dog bites among the postmen using multiple logistic regression analysis.

RESULTS

We found that, during the 3-year period of study, 71.4% (137/192) of the postmen had had the experience of dog bites. Only 48.9% (67/137) had sought medical attention after a dog bite injury. There was also a regional difference among postmen experiencing dog bites. After controlling multiple variables, there was a 2.70-fold increase in risk of having dog bite accidents among postmen who worked in rural areas compared with those who worked in urban areas (95% confidence interval, 1.39 to 5.25).

CONCLUSION

Dog bites are a common occupational hazard for postmen. The incidence of dog bites among postmen is higher than the reported rates among general populations. There is a need to develop an effective prevention strategy to reduce the occurrence of dog bites among postmen. We also emphasize the importance of seeking adequate medical treatment after a dog bite injury.

Relationship between pterygium/pinguecula and sunlight exposure among postmen in central Taiwan

BACKGROUND

The purpose of this study was to investigate outdoor hazards and their relationship to conjunctival disorders experienced by postmen.

METHODS

Three hundred and ninety-four employees (248 postmen and 146 officers) working in 11 post offices in central Taiwan were recruited and participated in the 1994 annual labor health examination. Pinguecula and pterygium were diagnosed by an ophthalmologist. Meanwhile, detailed personal and occupational information was obtained using a structured questionnaire. The cumulative occupational sunlight exposure was calculated for each postman by considering the duration of their employment as postmen, the average working hours per day and their spectacle use (sunglasses and eyeglasses). A logistic regression was used to analyze the relationship between cumulative occupational sunlight exposure and pinguecula.

RESULTS

Among the postmen, the prevalences of pinguecula and pterygium were 62.9% and 7.3%, respectively. The outdoor nature of postal work was significantly associated with the occurrence of pinguecula as well as pterygium (p < 0.05). When the cumulative occupational sunlight exposure increased by one unit (one year x hour/day), the risks of developing pinguecula and pterygium were raised by 2.1% and 0.8%, respectively.

CONCLUSIONS

The results indicate that conjunctival disorders were associated with the cumulative occupational sunlight exposure of postmen working outdoors. This study reinforces the importance of ocular protection from sunlight.

Predictive pulmonary function of school children in an area of low air pollution in Taiwan

The objective of this study was to determine the effect of different parameters on a predictive model of pulmonary function for elementary school children in an area of low air pollution in Taiwan. Healthy children aged 7 to 12 years from three elementary schools in low-air-pollution areas (Da-Chen, Mai-Liau and Tai-Si) participated in the study. A total of 836 children (423 boys and 413 girls) were included in the study. During summer vacation, each child underwent a physical examination including a screening spirometry. A questionnaire regarding respiratory symptoms and indoor air pollutants was also completed by the children's parents. Air monitoring showed that the levels of outdoor pollutants were relatively low. Multiple linear regression analysis was performed with FVC (forced vital capacity) and FEV1 (forced expiratory volume in 1 sec) as dependent variables. Gender, age, height, weight, technician and indoor air pollution parameters were the independent variables. The results showed that gender,height, weight and technician were the most significant variables for predicting FVC and FEV1. The various indoor air pollution parameters seemed to have no influence on the pulmonary function of children, except that mildew in bedrooms mildly decreased FEV1. Regression analysis showed that all the pulmonary function parameters measured had a positive correlation with height, whereas weight correlated only with certain parameters. Because both indoor and outdoor air pollution was relatively low, we suggest that this model could be used as a basic predictive model of pulmonary function for elementary school children in Taiwan.

Preliminary experience in pelviscopic uterine suspension using Webster-Baldy and Franke's method

OBJECTIVE

To find which method gives the best relief from dyspareunia and pelvic pain caused by a retroverted uterus using the two methods mentioned as compared to other methods reported in the medical literature.

SUBJECTS

Twenty-five patients, with ages ranging from 25-55 years old, complaining of mild to severe pelvic pain and dyspareunia seeking treatment in our OPD were evaluated and treated in a span of 3 years' time.

METHODS

Pelviscopic retrouterine ligament fixation using Webster-Baldy and Franke's method were done after each patient was evaluated as to the uterine position, degree of misalignment of the uterus and severity of adhesion. Pelvic pain and dyspareunia were reproduced by palpation of the retroverted uterus. Ultrasonographies were performed to confirm initial findings and to rule out any ovarian or uterine abnormalities. Orthopedic and psychological consultations were done to rule out any orthopedic disorders or non-organic causes of their problem.

RESULTS

Of the twenty-five patients treated, 20 patients were treated using Webster-Baldy method and five patients were treated using Franke's method, all the patients (100%) experienced great improvement 6 weeks after the operation. After 6 months, 16 patients (80%) with the Webster-Baldy method and four patients (80%) with the Franke's method had complete relief from pelvic pain and dyspareunia. The remaining four patients (20%) with the former method and one patient (20%) with the latter method complained of mild abdominal discomfort. After 6 months to 2 years of follow-up, 17 patients with Webster-Baldy method and five patients with Franke's method (88%) had improved sexual life and the remaining three patients were lost to follow-up.

CONCLUSION

When dyspareunia and pelvic pain are caused by a retroverted method, we believe uterine suspension using different procedures will certainly relieve this problem. We have presented and have chosen these two procedures mainly due to their simplicity and the almost nil possibility of bowel intussusception into the anterior cul-de-sac as compared to other methods.