Genetic and epigenetic variation separately contribute to range expansion and local metalliferous habitat adaptation during invasions of Chenopodium ambrosioides into China.

BACKGROUND AND AIMS: Invasive plants often colonize wide-ranging geographical areas with various local microenvironments. The specific roles of epigenetic and genetic variation during such expansion are still unclear. Chenopodium ambrosioides is a well-known invasive alien species in China that can thrive in metalliferous habitats. This study aims to comprehensively understand the effects of genetic and epigenetic variation on the successful invasion of C. ambrosioides. METHODS: We sampled 367 individuals from 21 heavy metal-contaminated and uncontaminated sites with a wide geographical distribution in regions of China. We obtained environmental factors of these sampling sites, including 13 meteorological factors and the contents of four heavy metals in soils. Microsatellite markers were used to investigate the demographic history of C. ambrosioides populations in China. We also analysed the effect of epigenetic variation on metalliferous microhabitat adaptation using methylation-sensitive amplified polymorphism (MSAP) markers. A common garden experiment was conducted to compare heritable phenotypic variations among populations. KEY RESULTS: Two distinct genetic clusters that diverged thousands of years ago were identified, suggesting that the eastern and south-western C. ambrosioides populations in China may have originated from independent introduction events without recombination. Genetic variation was shown to be a dominant determinant of phenotypic differentiation relative to epigenetic variation, and further affected the geographical distribution pattern of invasive C. ambrosioides. The global DNA unmethylation level was reduced in metalliferous habitats. Dozens of methylated loci were significantly associated with the heavy metal accumulation trait of C. ambrosioides and may contribute to coping with metalliferous microenvironments. CONCLUSIONS: Our study of C. ambrosioides highlighted the dominant roles of genetic variation in large geographical range expansion and epigenetic variation in local metalliferous habitat adaptation.

The Nitrogen Atom of Vitamin B6 Is Essential for the Catalysis of Radical Aminomutases.

Radical aminomutases are pyridoxal 5'-phosphate (PLP, a B6 vitamer)-dependent enzymes that require the generation of a 5'-deoxyadenosyl radical to initiate the catalytic cycle, to perform a 1,2 amino group shift reaction. The role of the nitrogen atom of PLP in radical aminomutases has not been investigated extensively yet. We report an alternative synthetic procedure to provide easy access to 1-deazaPLP (dAPLP), an isosteric analog of PLP which acts as a probe for studying the role of the nitrogen atom. Our results revealed that lysine 5,6-aminomutase (5,6-LAM), a radical aminomutase, reconstituted with dAPLP cannot turn over a substrate, demonstrating that the nitrogen atom is essential for radical aminomutases. In contrast, biochemical and spectroscopic studies on the S238A variant reconstituted with PLP revealed a minuscule loss of activity. This apparent anomaly can be explained by a water-mediated rescue of activity in S238A, as if mimicking the active site of lysine 2,3-aminomutase. This study leads to a better comprehension of how enzymes harness the optimum capability of PLP to realize catalysis.

Primulinasilaniae sp. nov. (Gesneriaceae) from the limestone area of Guizhou Province, China.

Primulinasilaniae X.X.Bai & F.Wen, a new species of Primulina Hance (Gesneriaceae) from the limestone area of Wangmo County, Guizhou Province, is described and illustrated. The new species is similar to P.spiradiclioides Z.B.Xin & F.Wen, but can be easily distinguished from the latter by a combination of characteristics, especially in the lateral veins of its leaf and floral shape and tube. At present, three populations in one locality of this new taxon were found, totaling about 600 mature individuals. According to the IUCN Red List Categories and Criteria (Version 3.1), the species is provisionally assessed as Vulnerable [VU D1].

Mesenteric lymphatic ducts ligation decreases the degree of gut-induced lung injury in a portal vein occlusion and reperfusion canine model.

BACKGROUND: Whether the mesenteric lymphatic system could serve as a route of transport by which gut-derived inflammatory mediators contribute to the induction of remote organ injuries is uncertain. We therefore made a gut-induced lung injury canine model by portal vein occlusion and reperfusion (PV O/R) and studied the role of mesenteric lymphatic ducts ligation (ML) to gut-induced lung injury with this model. MATERIAL AND METHODS: Eighteen mongrel dogs were divided into control, PV O/R, and PV O/R + ML groups. Cytokines and endotoxin levels in the portal vein and lymph from thoracic duct in different groups were tested. The permeability, myeloperoxidase activity, and histopathological investigation of intestine and lung were evaluated. RESULTS: Cytokines and endotoxin levels in the portal vein were significantly increased in experimental groups compared with control group (P < 0.05), and that in the lymph from thoracic duct were significantly increased in PV O/R group compared with control and PV O/R + ML group (P < 0.05). Lung permeability and MPO activity in PV O/R group were significantly higher than those in control and PV O/R + ML group (P < 0.05); intestinal permeability in experimental groups were significantly higher with respect to control group. The lung injury score in PV O/R group was significantly higher than those in control and PV O/R + ML group (P < 0.05) and the intestinal injury scores in experimental groups were significantly higher than control group (P < 0.05). CONCLUSIONS: The gut-induced lung injury canine model made by PV O/R is successful, and mesenteric lymphatic ducts ligation decreases the degree of gut-induced lung injury in this model.

Liver cold preservation induce lung surfactant changes and acute lung injury in rat liver transplantation.

AIM: To investigate the relationship between donor liver cold preservation, lung surfactant (LS) changes and acute lung injury (ALI) after liver transplantation. METHODS: Liver transplantation models were established using male Wistar rats. Donor livers were preserved in University of Wisconsin solution at 4  °C for different lengths of time. The effect of ammonium pyrrolidinedithiocarbamate (PDTC) on ALI was also detected. All samples were harvested after 3 h reperfusion. The severity of ALI was evaluated by lung weight/body weight ratio, lung histopathological score, serum nitric oxide (NO) and endothelin (ET)-1 levels, lung tumor necrosis factor (TNF)-α and interleukin (IL)-1ß levels. Lung surfactants (LSs) were determined by micellar electrokinetic capillary chromatography. RESULTS: With extended donor liver cold preservation time (CPT), lung histopathological scores, serum ET-1 levels, lung weight/body weight ratio and the level of TNF-α and IL-1ß in lung were increased significantly in the 180-min group compared with the sham group (3.16 ± 0.28 vs 1.12 ± 0.21, P < 0.001; 343.59 ± 53.97 vs 141.53 ± 48.48, P < 0.001; 0.00687 ± 0.00037 vs 0.00557 ± 0.00056, P < 0.001; 17.5 ± 3.0 vs 1.3 ± 0.3, P < 0.001; 10.8 ± 2.3 vs 1.8 ± 0.4, P < 0.001), but serum NO levels decreased remarkably (74.67 ± 10.01 vs 24.97 ± 3.18, P < 0.001). The expression of lung phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and phosphatidylserine (PS) increased when CPT was < 120 min, and decreased when CPT was > 180 min (PC: 1318.89 ± 54.79 vs 1011.18 ± 59.99, P < 0.001; PE: 1504.45 ± 119.96 vs 1340.80 ± 76.39, P = 0.0019; PI: 201.23 ± 34.82 vs 185.88 ± 17.04, P = 0.2265; PS: 300.43 ± 32.95 vs 286.55 ± 55.55, P = 0.5054). All these ALI-associated indexes could be partially reversed by PDTC treatment. CONCLUSION: Prolonged CPT could induce or inhibit the expression of LSs at the compensation or decompensation stage, and some antioxidants (e.g., PDTC) may reverse the pathological process partially.

NF-κB induced the donor liver cold preservation related acute lung injury in rat liver transplantation model.

BACKGROUND: We have observed at our clinical work that acute lung injury (ALI) often occurs in patients transplanted with donor livers persevered for long time. So, we conducted this study to investigate the influence of cold preservation time (CPT) of donor liver on ALI induced by liver transplantation (LT), and further study the role of nuclear factor-κB (NF-κB) in the process. METHODS: Wistar rats were used as donors and recipients to establish orthotopic rat liver transplantation models. Donor livers were preserved at 4°C for different lengths of time. The effect of NF-κB inhibitor, ammonium pyrrolidinedithiocarbamate (PDTC), on ALI was detected. All samples were harvested after 3 h reperfusion. The severity of liver injury was evaluated first. The expressions of tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) in liver tissue and liver outflow serum were measured respectively. The severity indexes of ALI, the activity of NF-κB and inhibitor-κBα (I-κBα) in lung/liver were measured accordingly. RESULTS: With the prolonged liver CPT, the liver damage associated indexes and ALI-related indexes all increased significantly. TNF-α and IL-1ß in liver outflow serum increased accordingly, and the activity of NF-κB in liver/lung increased correspondingly. All these ALI-associated indexes could be partially reversed by the use of PDTC. CONCLUSIONS: Extended CPT aggravates the damage of donor liver and induces the expressions of TNF-α and IL-1ß in liver. These inflammatory factors migrate to lung via liver outflow blood and activate NF-κB in lung, inducing ALI finally. NF-κB may play a critical role in LT-related ALI. Patients with or at risk of ALI may benefit from acute anti-inflammatory treatment with PDTC.