Changing fluxes of sediments and salts as recorded in lower River Murray wetlands, Australia
- Gell, Peter, Fluin, Jennie, Tibby, John, Haynes, Deborah, Khanum, Syeda, Walsh, Brendan, Hancock, Gary, Harrison, Jennifer, Zawadzki, Atun, Little, Fiona
- Authors: Gell, Peter , Fluin, Jennie , Tibby, John , Haynes, Deborah , Khanum, Syeda , Walsh, Brendan , Hancock, Gary , Harrison, Jennifer , Zawadzki, Atun , Little, Fiona
- Date: 2006
- Type: Conference proceedings
- Full Text:
- Description: The River Murray basin, Australia's largest, has been significantly impacted by changed flow regimes and increased fluxes of salts and sediments since settlement in the 1840s. The river's flood plain hosts an array of cut-off meanders, levee lakes and basin depression lakes that archive historical changes. Pre-European sedimentation rates are typically approx. 0.1-1 mm year-1, while those in the period after European arrival are typically 10 to 30 fold greater. This increased sedimentation corresponds to a shift in wetland trophic state from submerged macrophytes in clear waters to phytoplankton-dominated, turbid systems. There is evidence for a decline in sedimentation in some natural wetlands after river regulation from the 1920s, but with the maintenance of the phytoplankton state. Fossil diatom assemblages reveal that, while some wetlands had saline episodes before settlement, others became saline after, and as early as the 1880s. The oxidation of sulphurous salts deposited after regulation has induced hyperacidity in a number of wetlands in recent years. While these wetlands are rightly perceived as being heavily impacted, other, once open water systems, that have infilled and now support rich macrophyte beds, are used as interpretive sites. The rate of filling, however, suggests that the lifespan of these wetlands is short. The rate of wetland loss through such increased infilling is unlikely to be matched by future scouring as regulation has eliminated middle order floods from the lower catchment.
- Authors: Gell, Peter , Fluin, Jennie , Tibby, John , Haynes, Deborah , Khanum, Syeda , Walsh, Brendan , Hancock, Gary , Harrison, Jennifer , Zawadzki, Atun , Little, Fiona
- Date: 2006
- Type: Conference proceedings
- Full Text:
- Description: The River Murray basin, Australia's largest, has been significantly impacted by changed flow regimes and increased fluxes of salts and sediments since settlement in the 1840s. The river's flood plain hosts an array of cut-off meanders, levee lakes and basin depression lakes that archive historical changes. Pre-European sedimentation rates are typically approx. 0.1-1 mm year-1, while those in the period after European arrival are typically 10 to 30 fold greater. This increased sedimentation corresponds to a shift in wetland trophic state from submerged macrophytes in clear waters to phytoplankton-dominated, turbid systems. There is evidence for a decline in sedimentation in some natural wetlands after river regulation from the 1920s, but with the maintenance of the phytoplankton state. Fossil diatom assemblages reveal that, while some wetlands had saline episodes before settlement, others became saline after, and as early as the 1880s. The oxidation of sulphurous salts deposited after regulation has induced hyperacidity in a number of wetlands in recent years. While these wetlands are rightly perceived as being heavily impacted, other, once open water systems, that have infilled and now support rich macrophyte beds, are used as interpretive sites. The rate of filling, however, suggests that the lifespan of these wetlands is short. The rate of wetland loss through such increased infilling is unlikely to be matched by future scouring as regulation has eliminated middle order floods from the lower catchment.
Deficiency of MicroRNA-181a results in transcriptome-wide cell-specific changes in the kidney and increases blood pressure
- Paterson, Madeleine, Jackson, Kristy, Dona, Malathi, Farrugia, Gabriella, Visniauskas, Bruna, Watson, Anna, Johnson, Chad, Prieto, Minolfa, Evans, Roger, Charchar, Fadi, Pinto, Alexander, Marques, Francine, Head, Geoffrey
- Authors: Paterson, Madeleine , Jackson, Kristy , Dona, Malathi , Farrugia, Gabriella , Visniauskas, Bruna , Watson, Anna , Johnson, Chad , Prieto, Minolfa , Evans, Roger , Charchar, Fadi , Pinto, Alexander , Marques, Francine , Head, Geoffrey
- Date: 2021
- Type: Text , Journal article
- Relation: Hypertension Vol. 78, no. 5 (Nov 2021), p. 1322-1334
- Full Text:
- Reviewed:
- Description: MicroRNA miR-181a is downregulated in the kidneys of hypertensive patients and hypertensive mice. In vitro, miR-181a is a posttranslational inhibitor of renin expression, but pleiotropic mechanisms by which miR-181a may influence blood pressure (BP) are unknown. Here, we determined whether deletion of miR-181a/b-1 in vivo changes BP and the molecular mechanisms involved at the single-cell level. We developed a KO (knockout) mouse model lacking miR-181a/b-1 genes using CRISPR/Cas9 technology. Radiotelemetry probes were implanted in 12-week-old C57BL/6J WT (wild type) and miR-181a/b-1 KO mice. Systolic and diastolic BP were 4- to 5-mm Hg higher in KO compared with WT mice over 24 hours (P<0.01). Compared with WT mice, renal renin was higher in the juxtaglomerular cells of KO mice. BP was similar in WT mice on a high- (3.1%) versus low- (0.3%) sodium diet (+0.4 +/- 0.8 mm Hg), but KO mice showed salt sensitivity (+3.3 +/- 0.8 mm Hg; P<0.001). Since microRNAs can target several mRNAs simultaneously, we performed single-nuclei RNA sequencing in 6699 renal cells. We identified 12 distinct types of renal cells, all of which had genes that were dysregulated. This included genes involved in renal fibrosis and inflammation such as Stat4, Col4a1, Cd81, Flt3l, Cxcl16, and Smad4. We observed upregulation of pathways related to the immune system, inflammatory response, reactive oxygen species, and nerve development, consistent with higher tyrosine hydroxylase in the kidney. In conclusion, downregulation of the miR-181a gene led to increased BP and salt sensitivity in mice. This is likely due to an increase in renin expression in juxtaglomerular cells, as well as microRNA-driven pleiotropic effects impacting renal pathways associated with hypertension.
- Authors: Paterson, Madeleine , Jackson, Kristy , Dona, Malathi , Farrugia, Gabriella , Visniauskas, Bruna , Watson, Anna , Johnson, Chad , Prieto, Minolfa , Evans, Roger , Charchar, Fadi , Pinto, Alexander , Marques, Francine , Head, Geoffrey
- Date: 2021
- Type: Text , Journal article
- Relation: Hypertension Vol. 78, no. 5 (Nov 2021), p. 1322-1334
- Full Text:
- Reviewed:
- Description: MicroRNA miR-181a is downregulated in the kidneys of hypertensive patients and hypertensive mice. In vitro, miR-181a is a posttranslational inhibitor of renin expression, but pleiotropic mechanisms by which miR-181a may influence blood pressure (BP) are unknown. Here, we determined whether deletion of miR-181a/b-1 in vivo changes BP and the molecular mechanisms involved at the single-cell level. We developed a KO (knockout) mouse model lacking miR-181a/b-1 genes using CRISPR/Cas9 technology. Radiotelemetry probes were implanted in 12-week-old C57BL/6J WT (wild type) and miR-181a/b-1 KO mice. Systolic and diastolic BP were 4- to 5-mm Hg higher in KO compared with WT mice over 24 hours (P<0.01). Compared with WT mice, renal renin was higher in the juxtaglomerular cells of KO mice. BP was similar in WT mice on a high- (3.1%) versus low- (0.3%) sodium diet (+0.4 +/- 0.8 mm Hg), but KO mice showed salt sensitivity (+3.3 +/- 0.8 mm Hg; P<0.001). Since microRNAs can target several mRNAs simultaneously, we performed single-nuclei RNA sequencing in 6699 renal cells. We identified 12 distinct types of renal cells, all of which had genes that were dysregulated. This included genes involved in renal fibrosis and inflammation such as Stat4, Col4a1, Cd81, Flt3l, Cxcl16, and Smad4. We observed upregulation of pathways related to the immune system, inflammatory response, reactive oxygen species, and nerve development, consistent with higher tyrosine hydroxylase in the kidney. In conclusion, downregulation of the miR-181a gene led to increased BP and salt sensitivity in mice. This is likely due to an increase in renin expression in juxtaglomerular cells, as well as microRNA-driven pleiotropic effects impacting renal pathways associated with hypertension.
Reclamation of salt-affected land: A review
- Shaygan, Mandana, Baumgartl, Thomas
- Authors: Shaygan, Mandana , Baumgartl, Thomas
- Date: 2022
- Type: Text , Journal article
- Relation: Soil systems Vol. 6, no. 3 (2022), p. 61
- Full Text:
- Reviewed:
- Description: Reclamation of salt-affected soil has been identified by the FAO as being critical to meet the needs to increase agricultural productivity. This paper reviews commonly used reclamation methods for salt-affected soils, and provides critical identifiers for an effective reclamation practice of salt-affected soil. There are widely used methods to reduce salinity and sodicity of salt-affected soils, including salt leaching, addition of amendments, revegetation using halophytes and salt scrapping. Not all reclamation techniques are suitable for salt-affected land. The reclamation strategy must be tailored to the site, and based on understanding the soil, plant and climate interactions. On some occasions, a combination of techniques may be required for reclamation. This can include salt scrapping to remove salts from the surface soil, the addition of physical amendments to improve soil pore systems and enhance salt leaching, followed by amelioration of soil by chemical amendments to preserve soil physical conditions, and then halophyte establishment to expand the desalinization zone. This study reveals that soil hydro-geochemical models are effective predictive tools to ascertain the best reclamation practice tailored to salt-affected land. However, models need to be calibrated and validated to the conditions of the land before being applied as a tool to combat soil salinity.
- Authors: Shaygan, Mandana , Baumgartl, Thomas
- Date: 2022
- Type: Text , Journal article
- Relation: Soil systems Vol. 6, no. 3 (2022), p. 61
- Full Text:
- Reviewed:
- Description: Reclamation of salt-affected soil has been identified by the FAO as being critical to meet the needs to increase agricultural productivity. This paper reviews commonly used reclamation methods for salt-affected soils, and provides critical identifiers for an effective reclamation practice of salt-affected soil. There are widely used methods to reduce salinity and sodicity of salt-affected soils, including salt leaching, addition of amendments, revegetation using halophytes and salt scrapping. Not all reclamation techniques are suitable for salt-affected land. The reclamation strategy must be tailored to the site, and based on understanding the soil, plant and climate interactions. On some occasions, a combination of techniques may be required for reclamation. This can include salt scrapping to remove salts from the surface soil, the addition of physical amendments to improve soil pore systems and enhance salt leaching, followed by amelioration of soil by chemical amendments to preserve soil physical conditions, and then halophyte establishment to expand the desalinization zone. This study reveals that soil hydro-geochemical models are effective predictive tools to ascertain the best reclamation practice tailored to salt-affected land. However, models need to be calibrated and validated to the conditions of the land before being applied as a tool to combat soil salinity.
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