The progesterone receptor (PR) plays a critical role during ovulation. Mice lacking the PR gene are anovulatory due to a failure in the rupture of the preovulatory follicles. The pathways that operate downstream of PR to control ovulation are poorly understood. Using gene expression profiling, we identified peroxisome proliferator-activated receptor γ (PPARγ) as a target of regulation by PR in the granulosa cells of the preovulatory follicles during the ovulatory process. To investigate the function of PPARγ during ovulation, we created a conditional knockout mouse in which this gene was deleted via Cre-Lox-mediated excision in granulosa cells. When these mutant mice were subjected to gonadotropin-induced superovulation, the preovulatory follicles failed to rupture and the number of eggs released from the mutant ovaries declined drastically. Gene expression analysis identified endothelin-2, interleukin-6, and cyclic GMP-dependent protein kinase II as novel targets of regulation by PPARγ in the ovary. Our studies also suggested that cycloxygenase 2-derived metabolites of long-chain fatty acids function as endogenous activating ligands of PPARγ in the preovulatory follicles. Collectively, these studies revealed that PPARγ is a key mediator of the biological actions of PR in the granulosa cells and activation of its downstream pathways critically controls ovulation.

The plant-specific SHI-related sequence (SRS) family of transcription factors plays a vital role in growth regulation, plant development, phytohormone biosynthesis, and stress response. However, the genome-wide identification and role in the abiotic stress-related functions of the SRS gene family were not reported in white sweet clover (Melilotus albus). In this study, nine M. albus SRS genes (named MaSRS01-MaSRS09) were identified via a genome-wide search method. All nine genes were located on six out of eight chromosomes in the genome of M. albus and duplication analysis indicated eight segmentally duplicated genes in the MaSRS family. These MaSRS genes were classified into six groups based on their phylogenetic relationships. The gene structure and motif composition results indicated that MaSRS members in the same group contained analogous intron/exon and motif organizations. Further, promoter region analysis of MaSRS genes uncovered various growth, development, and stress-responsive cis-acting elements. Protein interaction networks showed that each gene has both functions of interacting with other genes and members within the family. Moreover, real-time quantitative PCR was also performed to verify the expression patterns of nine MaSRS genes in the leaves of M. albus. The results showed that nine MaSRSs were up- and down-regulated at different time points after various stress treatments, such as salinity, low-temperature, salicylic acid (SA), and methyl jasmonate (MeJA). This is the first systematic study of the M. albus SRS gene family, and it can serve as a strong foundation for further elucidation of the stress response and physiological improvement of the growth functions in M. albus.

To solve grid-scale problems and evaluation indicator selection in landscape ecological risk index (LERI) evaluation, this paper takes the Bailong River Basin in Gansu Province (BLRB) as an example. The LERI evaluation formulae and optimal grid scales were determined by screening landscape indices and area changes in the LERI at different grid scales. The evaluation indices were finally obtained according to the landscape characteristics and the correlation analysis of the landscape index value. Through the statistical analysis of the area of the LERI at the grid scale of 1–6 km, the optimal grid scale was determined to be 5 km. There was little change in land use patterns, with the most significant increases in artificial surfaces at 3.29% and 3.58%, respectively. Cultivated land was the only land use type to decrease by 184.3 km². The LERI drops with the reduced cultivated land area; the landscape ecological medium risk area and cultivated land keep the same spatial distribution. Due to the limitation of the topography, cultivated land is generally distributed below 2500 m altitude, so 2500 m becomes the turning point in the spatial distribution of the LERI. The medium risk below 2500 m dominates the LERI type. Reduced cultivated land was the leading cause of reduced ecological risk according to an overlay analysis. The study of LERI evaluations provides a theoretical basis for sustainable and ecological environmental protection in the BLRB.

The landscape diversity index (LDI) is an important level in biodiversity conservation, and its scale dependence has an important role in regional landscape planning and biological conservation. The aim of this study is to analyze in depth the effects of spatial scale changes in the classification of different landscape components on LDI and to explore the thresholds of LDI. The classification of landscape components was accomplished in the ArcMap environment using fusion and merging tools, and the LDI thresholds and scale changes were quantitatively assessed by LDI values. The results show that there are differences in LDI values for different classifications, and the threshold for LDI without considering scale changes can be interpreted as: 0.4215 ≤ LDI ≤ 1.9754. The grain sizes suitable for landscape diversity analysis are 160m and 1280 m, and the effective amplitude range of the I, II and III land type is 9~31 km, while the effective amplitude of three land use types is 20∼31 km, relatively lagging behind. However, when considering amplitude changes, the LDI threshold can be interpreted as 0.3027 ≤ LDI ≤ 2.0947, which is suitable for large-scale regional landscape diversity studies when the grain size is large. In conclusion, the essence of landscape diversity change with scale is caused by changes in the number and area of landscape components, and the threshold analysis should not only take into account the grain size and amplitude, but also consider the landscape background of the study area.

During early pregnancy, the attenuation of estrogen (E)-mediated proliferation of uterine epithelium by progesterone (P) is a prerequisite for successful embryonic implantation. Our recent studies revealed that the basic helix-loop-helix (bHLH) transcription factor Hand2 is induced in response to P signaling in uterine stroma at the time of implantation. To investigate the function of Hand2 in implantation, we created a conditional knockout of the Hand2 gene in the uterus of adult mice by employing the Cre-LoxP strategy. Ablation of Hand2 in the uterus led to female infertility due to the failure of embryos to attach to uterine epithelium. In the absence of Hand2, uterine epithelium remained proliferative and failed to transition to the receptive state that allows implantation. Our results revealed a unique mechanism in which P-induced expression of Hand2 in the uterine stromal compartment normally suppresses the production of several members of the fibroblast growth factor (FGF) family, which act as paracrine mediators of mitogenic effects of E on the epithelium. In mouse uteri lacking Hand2, continued induction of these FGFs in the stroma activates ERK/MAP kinase signaling, maintains epithelial proliferation, and stimulates E-induced pathways in this tissue that impair attachment of the embryo to the uterine epithelium. In normal pregnant mice, uterine expression of Hand2 continues in differentiating stromal cells surrounding the implanted embryo, suggesting a possible regulatory role of this factor in decidualization. Interestingly, the steroid hormone-primed stromal cells of the Hand2-ablated uteri were able to undergo proliferation in response to an artificial decidual stimulus. The Hand2-null stromal cells, however, failed to undergo terminal differentiation as indicated by the lack of expression of certain decidual biomarkers in these cells. Collectively, our findings identified Hand2 as a key mediator of P signaling in uterine stroma and established its role in controlling critical pathways that regulate uterine epithelial receptivity and stromal decidualization during implantation. (Supported by U54 HD055787 as part of the NICHD/NIH Centers Program in Reproduction and Infertility Research). (platform)

Lanzhou is the only provincial capital city in Northwest China where the main stream of the Yellow River and its tributaries flow through the city. Due to its geographical location and the influence of various factors, it is difficult to evaluate and simulate the climatic, hydrological, and ecological processes of the main stream of the Yellow River and its tributaries in the region. In this study, the Wanchuan River basin, currently undergoing ecological restoration, was selected as the study area. Seasonal backscatter differences generated using Sentinel-1/2 (S1/S2) data and the CD algorithm were used to reduce the effects of surface roughness; vegetation indices, soils, and field measurements were used to jointly characterize the vegetation contribution and soil contribution. Then, SM maps with a grid spacing of 10 m × 10 m were generated in the Wanchuan River basin, covering an area of 1767.78 km². To validate the results, optimal factors were selected, and a training set and validation set were constructed. The results indicated a high level of the coefficient of determination (R²) of 0.78 and the root mean square error (RMSE) of 0.08 for the comparison of measured and inverted water contents, indicating that the algorithm retrieved the SM values of the study area well. Furthermore, Box line plots with ERA5-Land and GLDAS confirmed that the algorithm is in good agreement with current SM products and feasibility for soil water content inversion work in the Wanchuan River basin.