RESUMEN
Enriched planting of native tree species in monoculture plantation forests is a commonly recommended forest practice. However, its effect on various ecological processes is generally lacking. Here, we carried out an experiment in a 16-year-old Eucalyptus plantation in South China to assess the effects of enriched planting of native tree species on surface water, soil erosion and nutrient losses. Two treatments were conducted in 2008: (1) enriched planting of native broadleaved tree species with uniform thinning of 60% of Eucalyptus trees (TEP); and (2) enriched planting of native broadleaved tree species without thinning (NEP). The original Eucalyptus plantation stands was used as the control (CK). Runoff plots (total n=9, 3 for each treatment or CK) were established in 2009, and surface water flow, sediment, nitrogen (N) and phosphorus (P) losses were monitored from major rainfall events in 2010-2012. Results showed that enriched planting in Eucalyptus plantation significantly reduced surface water flow and soil erosion. Compared with CK, TEP and NEP reduced annual surface water flow by 29-43% and 11-16%, and reduced annual soil erosion by 38-54% and 20-33% throughout the study period, respectively. TEP and NEP had significantly lower annual mean concentrations of N and P in surface water. Compared with CK, TEP reduced annual N and P losses through surface water by 42-60% and 44-64%, respectively, while NEP reduced them by 25-28% and 24-34%, respectively. N and P losses were significantly related to surface water flow. Between the two treatments, TEP was better for retaining water and soil, and for preventing nutrient loss. These results clearly demonstrated that the enriched planting of native tree species effectively retained surface water and nutrients.
Asunto(s)
Agricultura/métodos , Bosques , Movimientos del Agua , China , Eucalyptus , Nitrógeno/análisis , Fósforo/análisis , ÁrbolesRESUMEN
At present, classic therapies provide limited benefits to the survival of patients with pancreatic cancer. However, clinically available gene therapy strategies have not been well established. This study investigates the effect of shRNA-mediated inhibition of XIAP and survivin expression on the proliferation, apoptosis, and chemosensitivity of pancreatic cancer cells. Stable inhibition of XIAP and survivin expression in SW1990 and Panc-1 pancreatic cancer cells was established by lentivirus-carried shRNAs. The mRNA and protein expression of XIAP and survivin were detected by real-time PCR and Western blot, respectively. Cell proliferation was measured by MTT assay, and apoptosis was detected by caspase-3/7 activity and Hoechst33342 staining. The lentivirus-carried shRNA significantly inhibited XIAP and survivin expression. Simultaneous inhibition of XIAP and survivin expression in pancreatic cells significantly reduced cell proliferation, increased caspase-3/7 activity, and increased cell sensitization to 5-FU and gemcitabine treatments compared to inhibition of XIAP or survivin expression alone. However, simultaneous silencing of XIAP and survivin showed no significant difference in inducing cell apoptosis compared to silencing of XIAP or survivin expression alone. Simultaneous inhibition of XIAP and survivin expression may be an effective strategy for gene therapy of pancreatic cancer.