Transgenerational Epigenetic Inheritance Under Environmental Stress by Genome-Wide DNA Methylation Profiling in Cyanobacterium

Epigenetic modifications such as DNA methylation are well known as connected with many important biological processes. Rapid accumulating evidence shows environmental stress can generate particular defense epigenetic changes across generations in eukaryotes. This transgenerational epigenetic inheritance in animals and plants has gained interest over the last years. Cyanobacteria play very crucial role in the earth, and as the primary producer they can adapt to nearly all diverse environments. However, few knowledge about the genome wide epigenetic information such as methylome information in cyanobacteria, especially under any environment stress, was reported so far. In this study we profiled the genome-wide cytosine methylation from a model cyanobacterium Synechocystis sp. PCC 6803, and explored the possibility of transgenerational epigenetic process in this ancient single-celled prokaryote by comparing the DNA methylomes among normal nitrogen medium cultivation, nitrogen starvation for 72 h and nitrogen recovery for about 12 generations. Our results shows that DNA methylation patterns in nitrogen starvation and nitrogen recovery are much more similar with each other, significantly different from that of the normal nitrogen. This study reveals the difference in global DNA methylation pattern of cyanobacteria between normal and nutrient stress conditions and reports the evidence of transgenerational epigenetic process in cyanobacteria. The results of this study may contribute to a better understanding of epigenetic regulation in prokaryotic adaptation to and survive in the ever changing environment

Skin-Derived Mesenchymal Stem Cells Help Restore Function to Ovaries in a Premature Ovarian Failure Mouse Model

<div><p>Skin-derived mesenchymal stem cells (SMSCs) can differentiate into the three embryonic germ layers. For this reason, they are considered a powerful tool for therapeutic cloning and offer new possibilities for tissue therapy. Recent studies showed that skin-derived stem cells can differentiate into cells expressing germ-cell specific markers <i>in vitro</i> and form oocytes <i>in vivo</i>. The idea that SMSCs may be suitable for the treatment of intractable diseases or traumatic tissue damage has attracted attention. To determine the ability of SMSCs to reactivate injured ovaries, a mouse model with ovaries damaged by busulfan and cyclophosphamide was developed and is described here. Female skin-derived mesenchymal stem cells (F-SMSCs) and male skin-derived mesenchymal stem cells (M-SMSCs) from red fluorescence protein (RFP) transgenic adult mice were used to investigate the restorative effects of SMSCs on ovarian function. Significant increases in total body weight and the weight of reproductive organs were observed in the treated animals. Both F-SMSCs and M-SMSCs were shown to be capable of partially restoring fertility in chemotherapy-treated females. Immunostaining with RFP and anti-Müllerian hormone (AMH) antibodies demonstrated that the grafted SMSCs survived, migrated to the recipient ovaries. After SMSCs were administered to the treated mice, real-time PCR showed that the expression levels of pro-inflammatory cytokines TNF-α, TGF-β, IL-8, IL-6, IL-1β, and IFNγ were significantly lower in the ovaries than in the untreated controls. Consistent with this observation, expression of oogenesis marker genes Nobox, Nanos3, and Lhx8 increased in ovaries of SMSCs-treated mice. These findings suggest that SMSCs may play a role within the ovarian follicle microenvironment in restoring the function of damaged ovaries and could be useful in reproductive health.</p></div

Offspring produced by mating after SMSC transplantation into the mice sterilized by chemotherapy and those produced by untreated controls and normal controls.

<p>A) Litters of the different groups. B) Distribution of offspring in the treated and untreated groups. On average, significantly more pups were born to the mice that received chemotherapy plus F-SMSC- or M-SMSC-transplantation than to untreated controls (**, <i>P</i><0.01). However, the average number of pups produced by the normal control mice was still higher than the average number of pups from mice receiving F-SMSC- or M-SMSC-transplantation (**, <i>P</i><0.01).</p

SMSC administration decreased ovary inflammation and improved folliculogenesis transcription.

<p>A) Analysis of pro- and anti-inflammatory cytokine gene expression as performed by qPCR. Administration of SMSCs 7 days after chemotherapy resulted in significantly less gene expression for TNF-α, TGF-β, IL-8, IL-6, IL-1β, and IFN-γ than in untreated control mice (*<i>P</i><0.05, **<i>P</i><0.01, ***<i>P</i><0.01). B) Expression of oocyte-specific genes in treated and untreated recipient mouse ovaries. Quantitative real-time RT-PCR showed that the relative expression of Nobox, Nanos3, and Lhx 8 was significantly higher in the SMSC group compared than among untreated controls (**<i>P</i><0.01). 18s rRNA served as an internal housekeeping gene. Data represent mean±SE of 3 independent experiments.</p

Transplantation of a line of RFP-transgenic SMSCs into chemotherapy-sterilized recipient mice.

<p>A) Immunofluorescence of ovarian sections from sterilized mice 7 days after transplantation with RFP-transgenic SMSCs. Arrows indicate RFP staining in the ovarian stroma. B) RFP staining was observed around the antral follicle 21 days after transplantation. Asterisks indicate the antral follicle. C) RFP-positive cells were observed around granulosa cells in recipient ovaries 28 days after SMSC transplantation. D) RFP staining was observed in antral follicles of recipient ovaries 2 months after SMSC transplantation. Scale bars: A, C) 50 µm; B, D) 100 µm; A, insets) 20 µm; and B, D insets) 10 µm.</p

Double-staining of RFP and AMH in antral follicles of recipient ovaries 2 months after SMSC transplantation.

<p>A) DAPI. B) RFP staining cells. C) AMH staining cells. D) Merged image of A, B, and C. Scale bars: 50 µm; insets) 20 µm.</p

Changes in total body weight and weight of reproductive organs in treated, untreated control, and normal control animals over 8 weeks.

<p>A) Representative photograph depicting the body type of 12 week-old mice in the (a) untreated control group, treated groups (b, F-SMSCs; c, M-SMSCs), and (d) normal control group. B) The total body weight of untreated mice decreased over the study period. However, mice in both the F-SMSC-treated and M-SMSC-treated groups weighed significantly more than mice in the untreated control group from the second week onward (**, <i>P</i><0.01). C) Representative photograph of ovaries removed from (a) the untreated control group, treated groups (b, F-SMSCs; c, M-SMSCs), and (d) normal control group. D) As indicated, the total weight of ovaries in the treated groups (both M-SMSC- and F-SMSC-treated) showed remarkable increases over the study period except before the first week (**, <i>P</i><0.01). E) The total weight of the uteruses in the treated group was significantly higher than that of untreated controls from the third week onward (*, <i>P</i><0.05; **, <i>P</i><0.01). F) There was no obvious change in the total weight of the cervixes and vaginas during the study period until after the 7th and 8th weeks (**, <i>P</i><0.01).</p

The characterization and differentiation of mouse SMSCs.

<p>Morphology of A–B) F-SMSCs (a cell cluster in the middle of the dish) and C–D) M-SMSCs from RFP transgenic mice (scale bar, 200 µm). E) Phenotype of F-SMSCs by flow cytometry. Of the F-SMSCs, 96% expressed CD73 but not CD45, CD34, or CD14. F) M-SMSCs detected by flow cytometry. Of the M-SMSCs, 92% expressed CD73 but not CD45, CD34, or CD14. G) F-SMSCs and H) M-SMSCs were able to differentiate into adipocytes (oil red O staining), chondroblasts, and osteoblasts under standard in vitro differentiation conditions. The nuclei were counterstained with DAPI (blue) (scale bar, 50 µm).</p

PCR primer sequences.

<p>PCR primer sequences.</p