AtCAP2 is crucial for lytic vacuole biogenesis during germination by positively regulating vacuolar protein trafficking

Protein trafficking is a fundamental mechanism of subcellular organization and contributes to organellar biogenesis. AtCAP2 is an Arabidopsis homolog of the Mesembryanthemum crystallinum calcium-dependent protein kinase 1 adaptor protein 2 (McCAP2), a member of the syntaxin superfamily. Here, we show that AtCAP2 plays an important role in the conversion to the lytic vacuole (LV) during early plant development. The AtCAP2 loss-of-function mutant atcap2-1 displayed delays in protein storage vacuole (PSV) protein degradation, PSV fusion, LV acidification, and biosynthesis of several vacuolar proteins during germination. At the mature stage, atcap2-1 plants accumulated vacuolar proteins in the pre-vacuolar compartment (PVC) instead of the LV. In wild-type plants, AtCAP2 localizes to the PVC as a peripheral membrane protein and in the PVC compartment recruits glyceraldehyde-3-phosphate dehydrogenase C2 (GAPC2) to the PVC. We propose that AtCAP2 contributes to LV biogenesis during early plant development by supporting the trafficking of specific proteins involved in the PSV-to-LV transition and LV acidification during early stages of plant development.11Ysciescopu

NHX antiporters regulate the pH of endoplasmic reticulum and auxin-mediated development

AtNHX5 and AtNHX6 are endosomal Na+,K+/H+ antiporters that are critical for growth and development in Arabidopsis, but the mechanism behind their action remains unknown. Here, we report that AtNHX5 and AtNHX6, functioning as H+ leak, control auxin homeostasis and auxin-mediated development. We found that nhx5 nhx6 exhibited growth variations of auxin-related defects. We further showed that nhx5 nhx6 was affected in auxin homeostasis. Genetic analysis showed that AtNHX5 and AtNHX6 were required for the function of the ER-localized auxin transporter PIN5. Although AtNHX5 and AtNHX6 were co-localized with PIN5 at ER, they did not interact directly. Instead, the conserved acidic residues in AtNHX5 and AtNHX6, which are essential for exchange activity, were required for PIN5 function. AtNHX5 and AtNHX6 regulated the pH in ER. Overall, AtNHX5 and AtNHX6 may regulate auxin transport across the ER via the pH gradient created by their transport activity. H+-leak pathway provides a fine-tuning mechanism that controls cellular auxin fluxes

High risk of metabolic syndrome after delivery in pregnancies complicated by gestational diabetes

Aims: To investigate the risk of postpartum metabolic syndrome in women with GDM compared with those without GDM in a Chinese population. Methods: Tianjin GDM observational study included 1263 women with a history of GDM and 705 women without GDM. Multivariate logistic regression was used to assess risks of postpartum metabolic syndrome between women with and without GDM. Postpartum metabolic syndrome was diagnosed by two commonly used criteria. Results: During a mean 3.53 years of follow up, 256 cases of metabolic syndrome were identified by using the NCEPATPIII criteria and 244 cases by using the IDF criteria. Multivariable-adjusted odds ratios of metabolic syndrome in women with GDM compared with those without GDM were 3.66 (95% confidence interval [CI] 2.02-6.63) for NCEP ATPIII criteria and 3.90 (95% CI 2.13-7.14) for IDF criteria. Women with GDM had higher multivariable-adjusted odds ratios of central obesity, hypertriglyceridemia, and high blood pressure than women without GDM. The multivariable-adjusted odds ratios of low HDL cholesterol and hyperglycemia were not significant between women with and without GDM, however, the multivariable-adjusted odds ratio of hyperglycemia became significant when we used the modified criteria. Conclusions: The present study indicated that women with prior GDM had significantly higher risks for postpartum metabolic syndrome, as well as its individual components. (C) 2019 Elsevier B.V. All rights reserved.Peer reviewe

Chronic typhoid infection and the risk of biliary tract cancer and stones in Shanghai, China

Previous studies have shown a positive association between chronic typhoid carriage and biliary cancers. We compared serum Salmonella enterica serovar Typhi antibody titers between biliary tract cancer cases, biliary stone cases without evidence of cancer, and healthy subjects in a large population-based case-control study in Shanghai, China

Modeling a New Water Channel That Allows SET9 to Dimethylate p53

SET9, a protein lysine methyltransferase, has been thought to be capable of transferring only one methyl group to target lysine residues. However, some reports have pointed out that SET9 can dimethylate Lys372 of p53 (p53-K372) and Lys4 of histone H3 (H3-K4). In order to understand how p53 can be dimethylated by SET9, we measured the radius of the channel that surrounds p53-K372, first on the basis of the crystal structure of SET9, and we show that the channel is not suitable for water movement. Second, molecular dynamic (MD) simulations were carried out for 204 ns on the crystal structure of SET9. The results show that water leaves the active site of SET9 through a new channel, which is made of G292, A295, Y305 and Y335. In addition, the results of molecular docking and MD simulations indicate that the new water channel continues to remain open when S-adenosyl-L-methionine (AdoMet) or S-adenosyl-L-homocysteine (AdoHcy) is bound to SET9. The changes in the radii of these two channels were measured in the equilibrium phase at the constant temperature of 300 K. The results indicate that the first channel still does not allow water to get into or out of the active site, but the new channel is large enough to allow this water to circulate. Our results indicate that water can be removed from the active site, an essential process for allowing the dimethylation reaction to occur

SCAMP, VSR, and plant endocytosis

In plants, secretory carrier membrane proteins (SCAMPs) are integral membrane proteins localized to plasma membrane (PM) and trans-Golgi network (TGN)/early endosome, whereas vacuolar sorting receptors (VSRs) are type I integral membrane proteins localized to TGN and prevacuolar compartment (PVC)/late endosome in plant cells. Recent studies demonstrated that SCAMPs and VSRs exhibited distinct patterns of distribution in growing pollen tube and both proteins are found to be essential for pollen tube growth. Interestingly, similar to SCAMPs, VSRs are also found to locate in PM in pollen tube, indicating a possible role in endocytosis. This chapter summarizes the recent findings on plant SCAMPs and VSRs in respect to their possible roles in endocytic trafficking within plant cells

The Oxygen Reduction Reaction Rate of Metallic Nanoparticles during Catalyzed Oxidation

This work reports the oxygen reduction reaction (ORR) kinetics of metal nanoparticle catalysts between 500 and 600 °C at low oxygen partial pressures. Ex situ and in situ TEM measurements demonstrate catalyzed nanowire growth initially follows linear kinetics; characteristic of being ORR rate limited. The ORR rates of Ag, Au, Cu, Ni, Pd, Rh and Pt measured at 600 °C form a volcano plot versus relative oxidation potential. Cu nanoparticles produce the maximum ORR rate under these conditions

Effects of Current Annealing on Thermal Conductivity of Carbon Nanotubes

This work documents the annealing effect on the thermal conductivity of nanotube film (CNTB) and carbon nanotube fiber (CNTF). The thermal properties of carbon nanotube samples are measured by using the transient electro-thermal (TET) technique, and the experimental phenomena are analyzed based on numerical simulation. During the current annealing treatment, CNTB1 always maintains the negative temperature coefficient of resistance (TCR), and its thermal diffusivity increases gradually. When the annealing current is 200 mA, it increases by 33.62%. However, with the increase of annealing current, the TCR of CNTB2 changes from positive to negative. The disparity between CNTB2 and CNTB1 suggests that they have different physical properties and even structures along their lengths. The high-level thermal diffusivity of CNTB2 and CNTF are 2.28–2.46 times and 1.65–3.85 times higher than the lower one. The results show that the decrease of the thermal diffusivity for CNTB2 and CNTF is mainly caused by enhanced Umklapp scattering, the high thermal resistance and torsional sliding during high temperature heating