[Spatial and temporal variations of landscape ecological risk in the dry and hot valley of the Jinsha River during 2000-2020]. / 2000­2020年金沙江干热河谷景观生态风险的时空变化.

Scientific assessment of landscape ecological risk in ecologically fragile areas of the upper reaches of the Yangtze River is of great significance to regional ecological regulation and construction of the Yangtze River ecological security barrier. With the dry-hot valley area of Jinsha River in Yunnan Province as the research area, we constructed a landscape ecological risk evaluation model, and analyzed the spatial and temporal variations of regional landscape ecological risk. The results showed that the average values of landscape ecological risk index (LER) in the study area were 0.414, 0.398, and 0.462 in 2000, 2010 and 2020, respectively. The LER value of the whole region had reached a higher risk level by 2020. In 2000 and 2010, the landscape ecological risk zones of each level were staggered, and the high-risk zones showed a centralized distribution in 2020. During the two decades, the average LER of each section in the study area was around 0.42, which was close to the high risk level, indicating high landscape ecological risk level. The area of middle and low risk zones had decreased, while the area of high risk zone had significantly increased. The area of high risk zone in the western and middle sections was much higher than that in the eastern section. The area with significant changes of landscape ecological risk accounted for about 55% of the total study area, with obvious spatial agglomeration characteristics of significant increase and decrease of risk. The competition between government-led ecological management policies and measures and market-led land use activities was the main cause of landscape ecological risk variations in this region. In the future, the driving mechanism of climate change coupled with human activities on global and local landscape ecological risk changes in the study area should be uncovered to effectively cope with regional ecological risks.

[Relationship between changes of herbaceous plants and Oncomelania hupensis snail distribution under walnut forest of inhibition of snails in mountainous regions of Yunnan Province].

OBJECTIVE: To explore the relationship between the changes of herbaceous plants and Oncomelania hupensis snail distribution under the walnut forest of inhibition of snails in mountainous regions of Yunnan Province. METHODS: The experimental field was established at Sanying Village of Eryuan County, Yunnan Province, where the "Flourishing Forest and Controlling Snails Project" was implemented. The different stand ages (2, 4, 6, 8, 10 years)of walnut forest in experimental groups were selected based on the method of space replacing time, and the non-stocked land was served as a control group. The growth of forest, change of snails, number, biomass, overcast, height of the herbaceous plant and the soil moisture were investigated. RESULTS: The crown closure of 6-year-old walnut forest of inhibition of snails was 0.65. There were 11 species of herbaceous plant belonging to 11 genera, 6 families in 10-year-old forest and its crown closure was 0.77. Compared with the control group, the numbers of families, genera, and species of the 10-year-old forest were decreased by 64.71%, 69.44%, and 77.08%, and the biomass, overcast, and height of it decreased by 12.63%, 19%, and 22.18%, respectively. The soil moisture content (0-20 cm) monthly changes were increased obviously with the increase of stand age. There were no snails besides the control group and 2-year-old walnut forest. Compare with the control group, the occurrence rate of frames with living snails in the 2-year-old walnut forest was decreased by 50%, which was 1.25%. The density of living snails was decreased by 60.16%. CONCLUSIONS: The construction of walnut forest of inhibition of snails in mountainous regions of Yunnan Province are suitable for controlling the growth of herbaceous plants and altering the environment of snails. If the coalescence intercropped with crops is carried out, it is not only beneficial to the construction of good ecological environment, but also improves the utilization efficiencies of land, light, and thermal resource, and the income of peasants.

[Characteristics of carbon sequestration and apparent stability of new sequestered carbon in forested torrid red soil at dry-hot valley].

Great concerns about potential for carbon (C) sequestration in forested soil and the stability of the sequestered C have been exerted under the background of global climate change. Organic C density in soil and in soil physical and biochemical fractions at various stages (1991, 1997, 2003 and 2010) in Acacia auriculiformis stand afforested in 1991 were investigated at Dry-Hot Valley via density fractionation and acid hydrolysis. The results showed that organic C density at surface (0-15 cm) and subsurface (15-30 cm) soil layers was 1.40 kg x m(-2) and 0.99 kg x m(-2) after 19 years of afforestation, respectively. The annual C sequestration rates of surface and subsurface soil layers were 37.89 g x (m2 x a)(-1) and 16.84 g x (m2 x a)(-1) during 1991-2010, respectively, and the sequestration was accelerating. The ratio of organic C in heavy fraction to in surface soil was 71.44% in 2003, which was significantly higher than that in 2010 (67.99%). The recalcitrant carbon index (I(RC)) in light fraction was significantly higher than that in heavy fraction at surface or subsurface layers in 2003, but both decreased with aging of plantation, especially I(RC) in light fraction. Approximately 57% - 70% of new sequestered C was protected by physical mechanism and 33-49 percent was biochemical recalcitrant C during the stage from 12 to 19 years after afforestation. The results reveal that forested torrid red soil at Dry-Hot Valley may have a considerable capability of C sequestration. The biochemical stability of physically protected C is lower than the unprotected. Both the stability, however, decreases with the plantation age.

[Soil labile organic carbon contents and their allocation characteristics under different land uses at dry-hot valley].

Soil organic carbon (SOC), readily oxidation organic carbon (ROC), microbial biomass carbon (MBC)and dissolved organic carbon (DOC) contents and their allocation ratios were comparatively investigated under Leucaena leucocephala woodland, Acacia auriculiformis woodland, dry cropland and wasteland in dry-hot valley. Results showed that SOC contents were not significant differences among the four land uses with the range of 4.22-5.19 g x kg(-1). ROC contents under L. leucocephala (2.14 g x kg(-1)) and A. auriculiformis woodland (2.03 g x kg(-1)) were both significantly higher than those under dry cropland (1.38 g x kg(-1)) and wasteland (1.34 g x kg(-1)). The highest MBC and DOC contents both presented under dry cropland among the four land uses, whereas the lowest occurred under wasteland. ROC allocation ratios under woodlands were 1.3 to 1.6 times to those under dry cropland and wasteland. MBC and DOC allocation ratios under cropland were higher than those under other three land uses, and the ratios were closely among woodlands and wasteland. Plant residue amounts and management were primarily determined ROC contents, and soil water content and plant residue quantity were mainly affected the variation of MBC and DOC contents under the four land uses. The change of ROC contents could sensitively indicate SOC dynamics in dry-hot valley, but the change of MBC or DOC could not.

[Detection and significance of phosphatidylinositol 3-kinase in adipose tissue of polycystic ovary syndrome patients with insulin resistance].

OBJECTIVE: To investigate the expression of phosphatidylinositol 3-kinase (PI-3K) in adipose tissue of polycystic ovary syndrome patients (PCOS), and explore molecular mechanisms of insulin resistance (IR) in PCOS. METHODS: Samples from patients with PCOS with IR (n = 19), PCOS without IR (n = 10) and controls (n = 15) were collected. Serum fasting insulin (FIN) and fasting plasma glucose (FPG) were measured. Insulin resistance index was calculated using homeostasis model assessment (HOMA) to analyze the relationship between these markers and IR. Western blot technique was used to detect the PI-3K p85 subunit. Gene expression of PI-3K p85 subunit was detected by reverse transcription polymerase chain reaction (RT-PCR) method. Kinase activity was detected by immunoprecipitation, thin-layer chromatography and gamma scintillation counting. RESULTS: (1) The levels of FIN [(25.2 +/- 3.8) mU/L] and HOMA-IR (1.6 +/- 0.3) in PCOS with IR were significantly higher than those in PCOS without IR [(13.4 +/- 3.8) mU/L, 0.9 +/- 0.3] and controls [(9.5 +/- 2.6) mU/L, 0.5 +/- 0.3; all P < 0.05). (2) There was no significant difference in the protein (0.65 +/- 0.10) and gene expression (0.92 +/- 0.12) of PI-3K p85 subunit in PCOS with IR compared with PCOS without IR (0.72 +/- 0.10, 1.01 +/- 0.10) and control groups (0.73 +/- 0.14, 1.00 +/- 0.12; P > 0.05). (3) PI-3K activity in PCOS with IR (81%) and PCOS without IR (89%) was significantly decreased (P < 0.01, P < 0.05) and negatively correlated with HOMA-IR (r = -0.69, P < 0.01; r = -0.62, P < 0.05). CONCLUSIONS: No significant difference in the protein and gene expression of PI-3K p85 subunit in PCOS with IR is found. The decreased PI-3K activity may lead to IR of PCOS.

[Tyrosine phosphorylation and protein expression of insulin receptor substrate-2 in the adipose tissue from patients with polycystic ovary syndrome].

OBJECTIVE: To explore molecular mechanisms of insulin resistance of polycystic ovary syndrome (PCOS) by determining the tyrosine phosphorylation and protein expression of insulin receptor substrate-2 (IRS-2) in adipose tissue from patients with PCOS. METHODS: Serum and subcutaneous adipose tissue samples from patients with PCOS with insulin resistance (n = 19), PCOS without insulin resistance (n = 17) and controls (n = 20) were collected. The expression of IRS-2 in adipose tissue was assessed by Western blot. Immunohistochemistry was used to detect the distribution of IRS-2 in adipose tissues of all patients. The tyrosine phosphorylation of IRS-2 was measured by immunoprecipitation and enhanced chemiluminescent immunoblotting technique. RESULTS: (1) There was no significant difference of the protein expression of IRS-2 in PCOS with insulin resistance 1.15 +/- 0.26 compared to those in PCOS without insulin resistance 1.13 +/- 0.26 and control group 1.00 +/- 0.25 (P > 0.05); (2) The tyrosine phosphorylation of IRS-2 was significantly decreased in PCOS with insulin resistance 0.77 +/- 0.16 compared to that of PCOS without insulin resistance 0.91 +/- 0.25 and control groups 1.00 +/- 0.12 (P < 0.05). There was no significant difference between PCOS without insulin resistance and control groups (P > 0.05). CONCLUSIONS: The decrease of tyrosine phosphorylation of IRS-2 in PCOS patients, which induces impairment of the insulin signal pathway, may be one of the mechanisms leading to insulin resistance.

[Tyrosine phosphorylation and protein expression of insulin receptor substrate-1 in the patients with polycystic ovary syndrome].

OBJECTIVE: To investigate the tyrosine phosphorylation and protein expression of insulin receptor substrate-1 in adipose tissue from patients with polycystic ovary syndrome, and explore molecular mechanisms of insulin resistance of PCOS. METHODS: Samples from patients with PCOS with insulin resistance (group A, n = 19), PCOS without insulin resistance (group B, n = 10) and controls group (n = 15) were collected. Serum luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone (T) were measured by chemiluminescence assay. Fasting insulin (FIN) was measured by radioimmunoassay. Fasting plasma glucose (FPG) was measured by oxidase assay. Insulin resistance index was calculated using homeostasis model assessment (HOMA) to analyze the relationship between these markers and insulin resistance. The amount of insulin receptor substrate-1 in adipose tissue was assessed by western blot. The tyrosine phosphorylation of IRS-1 was measured by immunoprecipitation. RESULTS: (1) The levels of serum LH (15.8 +/- 2.8) U/L, LH/FSH 2.8 +/- 0.6, T (4.3 +/- 0.9) nmol/L, FIN (25.2 +/- 3.8) mU/L and HOMA IR (1.56 +/- 0.25) in group A were significantly higher than those of group B (13.9 +/- 1.9) U/L, 2.3 +/- 0.4, (3.6 +/- 0.4) nmol/L, (13.4 +/- 3.8) mU/L, 0.87 +/- 0.28 and control group (7.3 +/- 2.1) U/L, 1.3 +/- 0.3, (0.9 +/- 0.2) nmol/L, (9.5 +/- 2.6) mU/L, 0.50 +/- 0.30 (all P < 0.05); (2) The protein expression and tyrosine phosphorylation of IRS-1 in group A (690 +/- 19 and 528 +/- 72 respectively) were significantly lower than those in group B (892 +/- 31, 801 +/- 64) and control group (988 +/- 29, 1139 +/- 124) (P < 0.05, and P < 0.01 respectively). (3) Insulin resistance index in group A and group B were negatively related with protein expression and tyrosine phosphorylation (r = -0.52, P < 0.05; r = -0.61, P < 0.01 and r = -0.60, P < 0.05; r = -0.63, P < 0.05). CONCLUSIONS: The signal transduction malfunction because of protein expression and tyrosine phosphorylation changes of IRS-1 in adipose tissue from polycystic ovary syndrome patients may be one of the mechanisms leading to insulin resistance.