[Comparison of root traits of Stipa krylovii and Allium polyrhizum under grazing in typical steppe.] / æ”¾ç‰§å½±å“ä¸‹å ¸åž‹è‰åŽŸå ‹æ°é’ˆèŒ å’Œå¤šæ ¹è‘±æ ¹ç³»å±žæ€§æ¯”è¾ƒ.

Plant ecological adaptation is associated with root traits. To clarify the differences of root traits between two dominant species, Stipa krylovii and Allium polyrhizum, under different grazing intensities (light, moderate, and heavy grazing intensities), we measured root traits, including root length, root surface area, root diameter, root volume, root tips, root bifurcations, specific root length, and specific surface area. We analyzed the root morphological patterns of tip proportion, length proportion, surface proportion and volume proportion of both species, and examined their ecological adaptation strategies under grazing. The results showed that grazing inhibited aboveground and belowground growth of S. krylovii, but promoted belowground growth of A. polyrhizum. In addition, the effects of grazing on belowground part of S. krylovii was greater than aboveground part. These results indicated that the growth of S. krylovii was maintained by the aboveground part and that of A. polyrhizum was maintained by the belowground part under grazing. Root length, root bifurcations, root surface area and root tips were the main factors affecting root traits of S. krylovii, while root length, root surface area and root volume were the main factors affecting root traits of A. polyrhizum. S. krylovii could adapt to grazing stress by increasing length proportion, surface proportion and volume proportion of diameter class of 0-0.7 mm, while A. polyrhizum by increasing the length proportion, surface proportion and volume proportion of diameter class of 1.4-1.8 mm. The study on the differences of root traits between S. krylovii and A. polyrhizum could help provide a scientific basis for controlling grassland degradation.

Structural and functional analyses of hepatitis B virus X protein BH3-like domain and Bcl-xL interaction.

Hepatitis B virus (HBV) X protein, HBx, interacts with anti-apoptotic Bcl-2 and Bcl-xL proteins through its BH3-like motif to promote HBV replication and cytotoxicity. Here we report the crystal structure of HBx BH3-like motif in complex with Bcl-xL where the BH3-like motif adopts a short α-helix to snuggle into a hydrophobic pocket in Bcl-xL via its noncanonical Trp120 residue and conserved Leu123 residue. This binding pocket is ~2 Å away from the canonical BH3-only binding pocket in structures of Bcl-xL with proapoptotic BH3-only proteins. Mutations altering Trp120 and Leu123 in HBx impair its binding to Bcl-xL in vitro and HBV replication in vivo, confirming the importance of this motif to HBV. A HBx BH3-like peptide, HBx-aa113-135, restores HBV replication from a HBx-null HBV replicon, while a shorter peptide, HBx-aa118-127, inhibits HBV replication. These results provide crucial structural and functional insights into drug designs for inhibiting HBV replication and treating HBV patients.

Impaired endothelial function in the brachial artery after Kawasaki disease and the effects of intravenous administration of vitamin C.

BACKGROUND: Previous studies in patients with a history of Kawasaki disease have focused on vascular endothelial function in coronary arteries, and the endothelial function of systemic arteries is not fully understood. Furthermore the effect of vitamin C on systemic endothelial function after Kawasaki disease has not been elucidated. OBJECTIVES: We attempted to analyze endothelium-dependent vasodilatation in the brachial artery after Kawasaki disease by using high resolution ultrasonography and to investigate whether the acute administration of vitamin C could restore such systemic endothelial dysfunction. METHODS: We compared 39 patients (7.1 +/- 2.7 years) 1.0 to 9.6 years after acute Kawasaki disease with 17 matched healthy subjects (7.0 +/- 3.1 years) as controls. Using high resolution vascular ultrasound, we measured brachial artery responses to reactive hyperemia (with increased flow causing endothelium-dependent dilatation) and sublingual nitroglycerin (causing endothelium-independent dilatation). RESULTS: The percent change in diameter of the brachial artery induced by reactive hyperemia in the patients with a history of Kawasaki disease (6.2 +/- 3.9%) was significantly lower than that in the control group (14.1 +/- 6.8%; P < 0.0001). No significant difference could be found in percent change in diameter induced by sublingual administration of nitroglycerin between the control (33.2 +/- 13.7%) and the patients with a history of Kawasaki disease (30.6 +/- 9.2%; P = 0.49). There was no significant difference in percent change in diameter of the brachial artery induced by reactive hyperemia between the patients who received gamma-globulin (6.0 +/- 4.0%) and those who did not receive gamma-globulin (7.9 +/- 3.3%; P = 0.33). Intravenous infusion of vitamin C significantly increased the percent change in diameter of brachial artery induced by reactive hyperemia in 19 patients with history of Kawasaki disease (6.6 +/- 3.5 to 13.0 +/- 5.5%; P < 0.0001), whereas no significant increase was seen in the percent change in diameter of brachial artery induced by reactive hyperemia in 20 patients with history of Kawasaki disease after placebo administration (6.5 +/- 4.5 to 7.3 +/- 4.9%; P = 0.20). CONCLUSIONS: Our study showed decreased percent change in diameter of the brachial artery induced by reactive hyperemia in patients with history of Kawasaki disease compared with the healthy children, indicating that systemic endothelial dysfunction exits after Kawasaki disease. Although such systemic endothelial dysfunction after Kawasaki disease is not influenced by early treatment with high dose gamma-globulin in the acute stage of Kawasaki disease, it can be restored by the acute intravenous administration of vitamin C.