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Soil water deficits have presented challenges to vegetation restoration in rocky desertification areas. In the field, small volumes of soil resources are present only in near-surface crevices, fissures, and other similar features. Water stored in the soil in near-surface fissures can help plants grow in such areas. The goals of this study are to discuss the soil water retention functions of near-surface fissures in terms of soil structure, water infiltration and water storage capacity and to define the role of fissure water in the growth of plants in rocky desertification areas. Several near-surface fissures with four types of vegetation (i.e., crops, grass, shrubs and trees) within a rocky karst desertification area on the Karst Plateau in Guizhou Province, China, were examined. Soil physicochemical property analysis and stable isotope techniques were applied. Fissures with shrubs and trees present high levels of soil porosity, while fissures with crops and grasses present low levels of soil porosity. The water infiltration rates of the soil in all of the examined fissures are higher than the rainfall intensity of the maximum daily rainfall for this province. Consequently, most rainwater infiltrates through the fissure soils. Compared to the other fissures, fissures with crops present higher levels of usable soil storage capacity in the surface soils (0–20 cm), which are affected by tillage (ploughing), but exhibit lower capacities in the bottom soil layer. Additionally, tree and shrub fissures present higher usable soil storage capacities in bottom soil layer than other types of fissures. The main source of water for Ligustrum and Pyracantha in the dry season is fissure water, which accounts for 44.7% and 58.2% of all the water utilized by these species, respectively. Fissure water may represent the most important source of water for plants growing in near-surface karst fissures.

Near-surface karst fissures are filled with soils. These soils are often derived from the erosion and transport of surface soil but have different properties than the surface soil in karst rocky desertification regions. This study was undertaken to determine the soil structure and nutrient contents in underground fissures with different grades of rocky desertification (no, potential, mild, moderate and severe). Based on field surveys, near-surface karst fissures were selected in a typical karst plateau area. Soil particle compositions, particularly nutrient characteristics, were determined through field sampling and laboratory experiments. The results indicated that the higher the rock desertification grade was, the higher the soil sand (0.02–2 mm) content and the lower the clay (

Surface erosion and underground leakage loss simultaneously exist on slopes with a double‐layered structure (surface and underground) and have caused rocky desertification in karst regions. Because of the great difficulty of directly determining the underground leakage loss of soil and water, soil erosion processes in this region remain unclear, especially underground leakage loss. The aim of this study was to reveal the plot‐scale characteristics of surface soil erosion and underground leakage loss of yellow soils on karst slopes. Simulated rainfall tests and field runoff plot monitoring were conducted to achieve this aim. We found that surface erosion formed on steep slopes (30°) or at greater rainfall intensities (over 50 mm hr⁻¹) and that surface runoff and surface soil loss dominated the total runoff and soil loss on karst slopes at greater rainfall intensities. However, underground leakage loss always occurred at different slopes and rainfall intensities. For small rainfall intensity cases (lower than 80 mm hr⁻¹), underground runoff and underground soil leakage loss dominated the total runoff and soil loss and showed an underground runoff ratio of over 90% and an underground soil leakage ratio of over 44%. Rainfall intensity had significant effects on surface runoff depth and surface soil loss rates but an insignificant influence on underground leakage loss. Slope gradient and slope length influenced the runoff yield, and slope degree had a greater effect on the surface soil loss than had slope length. This study improves our understanding of surface erosion and underground leakage loss in karst rocky desertification regions.

The restoration of vegetation in the rocky desertified areas of karst plateaus is a major problem for present-day ecological studies. The aim of this study was to determine the effects of vegetation restoration on the distribution and accumulation of trace elements in rhizosphere and non-rhizosphere soils. Four representative areas containing the plants Coriaria nepalensis Wall., Pinus armandii Franch., Elaeagnus pungens Thunb., and Cotoneaster hissaricus Pojark. were selected within a vegetation restoration area in the Karst Plateau of Caohai County, Guizhou Province, China. Soils were sampled using a grid method to measure the total contents of the trace elements iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in rhizosphere and non-rhizosphere soils. The representative area containing Elaeagnus displayed the greatest amount of accumulation in the rhizosphere of both total and available trace elements, except for total Zn. Representative areas of the rhizosphere with other types of vegetation showed accumulation of only some of the trace elements studied. All types of vegetation were associated with the bioenrichment of available trace elements in both rhizosphere and non-rhizosphere soils, except for available Cu in areas associated with Cotoneaster. Representative areas containing Pinus displayed the greatest degree of bioenrichment for both total and available trace elements in both rhizosphere and non-rhizosphere soils.

Karst rocky desertification and vegetation restoration have become major environmental and social problems throughout the world. In regions facing rocky karst desertification, any form of residual soil is pivotal to vegetation growth and the restoration of rocky desertification. The goals of this study were to discover the impact of vegetation restoration on soil properties in near-surface fissures of karst rocky desertification regions, and analyses of the physical and chemical properties of soil and stable isotope techniques were used to achieve these goals. We found that the morphological structures of karst near-surface fissures are diverse. Fissures with grass and shrubs exhibit improved soil bulk density and more fine soil particles than those with other vegetation. Fissures with shrubs have higher soil field capacity, an increased capillary water content and a greater field capacity, whereas fissures with grass display greater fertility, particularly with respect to hydrolysable nitrogen, and greater available phosphorus and potassium contents, which create conditions that are superior to those found in areas with other crops, shrubs and even trees. Karst near-surface fissures are the optimal locations for vegetation restoration in areas of karst rocky desertification. Fissures with grass have a better soil structure, a higher water content and improved fertility compared with other fissure with growing crops, shrub grasses and forests with certain soil degradation. The use of grasses should be prioritized to improve soil conditions and to advance sustainable land use during the implementation of vegetation restoration projects in karst rocky desertification regions, particularly in highly fissured areas.

Leakage loss of soil and water is the main reason for karst rocky desertification, and the concomitant nutrient loss/leakage carried by soil and sediment is an important factor that affects groundwater quality. Due to the difficulty in measuring the underground leakage of soil water, the amount of nutrient loss/leakage on a karst slope is currently unknown. A karst slope farmland is simulated in a laboratory based on field investigations in slope farmlands in a karst plateau region in Guizhou Province, China. Rainfall experiments were conducted to determine the surface losses and underground leakages of soil, water, nitrogen, phosphorus, and potassium, as well as the effects of rainfall intensity and slope on these factors in karst slope farmlands. Surface runoff occurs only at rainfall intensities greater than 30 mm/h, but underground runoff occurs under all rainfall intensity conditions. Moreover, underground leakage loss is the main mode of water loss. Soil loss on a karst slope farmland is a process that transitions from underground leakage to surface erosion as the rainfall intensity increases. The concentrations of total nitrogen (TN), total phosphorus (TP), and total potassium (TK) in surface runoff increase with increasing rainfall intensity and decrease with increasing slope gradient. The total loss loads of TN and TK in runoff and sediment increase with increasing rainfall intensity or slope gradient. The total nutrient loss loads of TN and TP are dominated by runoff losses, but the TK loss load is dominated by sediment losses.

Pancreatic cancer is a fatal human malignancy associated with an exceptionally poor prognosis. Novel therapeutic strategies are urgently required to treat this disease. In addition to immunosuppressive activity, triptolide possesses strong antitumor activity and synergistically enhances the antitumor activities of conventional chemotherapeutic drugs in preclinical models of pancreatic cancer. The present study investigated the antitumor effects of triptolide in pancreatic cancer cells, either in combination with gemcitabine, or alone. The pancreatic cancer BxPC-3 and PANC-1 cell lines were treated with triptolide, which resulted in time- and dose-dependent growth arrest. When incorporated into a sequential schedule, triptolide synergistically increased gemcitabine-induced cell growth inhibition and apoptosis, in addition to the cooperative regulation of B-cell lymphoma 2 family proteins and loss of mitochondrial membrane potential. Furthermore, triptolide enhanced gemcitabine-induced S phase arrest and DNA double-strand breaks, possibly through checkpoint kinase 1 suppression. The results of the present study suggest that triptolide has therapeutic potential for the treatment of pancreatic cancer, particularly when administered in combination with gemcitabine.

Pancreatic cancer is a fatal malignancy worldwide and urgently requires valid therapies. Previous research showed that the HDAC inhibitor chidamide is a promising anti-cancer agent in pancreatic cancer cell lines. In this study, we elucidate a probable underlying anti-cancer mechanism of chidamide involving the degradation of Mcl-1. Mcl-1 is frequently upregulated in human cancers, which has been demonstrated to participate in oxidative phosphorylation, in addition to its anti-apoptotic actions as a Bcl-2 family member. The pancreatic cancer cell lines BxPC-3 and PANC-1 were treated with chidamide, resulting in Mcl-1 degradation accompanied by induction of Mcl-1 ubiquitination. Treatment with MG132, a proteasome inhibitor reduced Mcl-1 degradation stimulated by chidamide. Chidamide decreased O2 consumption and ATP production to inhibit aerobic metabolism in both pancreatic cancer cell lines and primary cells, similar to knockdown of Mcl-1, while overexpression of Mcl-1 in pancreatic cancer cells could restore the aerobic metabolism inhibited by chidamide. Furthermore, chidamide treatment or Mcl-1 knockdown significantly induced cell growth arrest in pancreatic cancer cell lines and primary cells, and Mcl-1 overexpression could reduce this cell growth inhibition. In conclusion, our results suggest that chidamide promotes Mcl-1 degradation through the ubiquitin-proteasome pathway, suppressing the maintenance of mitochondrial aerobic respiration by Mcl-1, and resulting in inhibition of pancreatic cancer cell proliferation. Our work supports the claim that chidamide has therapeutic potential for pancreatic cancer treatment.

Progestagen-associated endometrial protein (PAEP) is a glycoprotein of the lipocalin family that acts as a negative regulator of T cell receptor-mediated activation. However, the function of tumor-derived PAEP on the human immune system in the tumor microenvironment is unknown. PAEP is highly expressed in intermediate and thick primary melanomas (Breslow's 2.5mm or greater) and metastatic melanomas, correlating with its expression in daughter cell lines established in vitro. The current study investigates the role of melanoma cell-secreted PAEP protein in regulating T cell function. Upon the enrichment of CD3+, CD4+ and CD8+ T cells from human peripheral blood mononuclear cells, each subset was then mixed with either melanoma-derived PAEP protein or PAEP-poor supernatant of gene-silenced tumor cells. IL-2 and IFN-γ secretion of CD4+ T cells significantly decreased with the addition of PAEP-rich supernatant. And the addition of PAEP-positive cell supernatant to activated lymphocytes significantly inhibited lymphocyte proliferation and cytotoxic T cell activity, while increasing lymphocyte apoptosis. Our result suggests that melanoma cell-secreted PAEP protein immunosuppresses the activation, proliferation and cytotoxicity of T lymphocytes, which might partially explain the mechanism of immune tolerance induced by melanoma cells within the tumor microenvironment.