The translocase of the inner mitochondrial membrane 22-2 is required for mitochondrial membrane function during Arabidopsis seed development.

The carrier translocase (also known as translocase of the inner membrane 22; TIM22 complex) is an important component of the mitochondrial protein import apparatus. However, the biological functions of AtTIM22-2 in Arabidopsis remain poorly defined. Here, we report studies on two tim22-2 mutants that exhibit defects in embryo and endosperm development, leading to seed abortion. AtTIM22-2, which was localized in mitochondria, was widely expressed in embryos and in various seedling organs. Loss of AtTIM22-2 function resulted in irregular mitochondrial cristae, decreased respiratory activity, and a lower membrane potential, together with changes in gene expression and enzyme activity related to reactive oxygen species (ROS) metabolism, leading to increased accumulation of ROS in the embryo. The levels of transcripts encoding mitochondrial protein import components were also altered in the tim22-2 mutants. Furthermore, mass spectrometry, bimolecular fluorescence complementation and co-immunoprecipitation assays revealed that AtTIM22-2 interacted with AtTIM23-2, AtB14.7 (a member of Arabidopsis OEP16 family encoded by At2G42210), and AT5G27395 (mitochondrial inner membrane translocase complex, subunit TIM44-related protein). Taken together, these results demonstrate that AtTIM22-2 is essential for maintaining mitochondrial membrane functions during seed development. These findings lay the foundations for a new model of the composition and functions of the TIM22 complex in higher plants.

Functional divergence of chloroplast Cpn60α subunits during Arabidopsis embryo development.

Chaperonins are a class of molecular chaperones that assist in the folding and assembly of a wide range of substrates. In plants, chloroplast chaperonins are composed of two different types of subunits, Cpn60α and Cpn60ß, and duplication of Cpn60α and Cpn60ß genes occurs in a high proportion of plants. However, the importance of multiple Cpn60α and Cpn60ß genes in plants is poorly understood. In this study, we found that loss-of-function of CPNA2 (AtCpn60α2), a gene encoding the minor Cpn60α subunit in Arabidopsis thaliana, resulted in arrested embryo development at the globular stage, whereas the other AtCpn60α gene encoding the dominant Cpn60α subunit, CPNA1 (AtCpn60α1), mainly affected embryonic cotyledon development at the torpedo stage and thereafter. Further studies demonstrated that CPNA2 can form a functional chaperonin with CPNB2 (AtCpn60ß2) and CPNB3 (AtCpn60ß3), while the functional partners of CPNA1 are CPNB1 (AtCpn60ß1) and CPNB2. We also revealed that the functional chaperonin containing CPNA2 could assist the folding of a specific substrate, KASI (ß-ketoacyl-[acyl carrier protein] synthase I), and that the KASI protein level was remarkably reduced due to loss-of-function of CPNA2. Furthermore, the reduction in the KASI protein level was shown to be the possible cause for the arrest of cpna2 embryos. Our findings indicate that the two Cpn60α subunits in Arabidopsis play different roles during embryo development through forming distinct chaperonins with specific AtCpn60ß to assist the folding of particular substrates, thus providing novel insights into functional divergence of Cpn60α subunits in plants.

Lipoic acid alleviates LPS­evoked PC12 cell damage by targeting p53 and inactivating the NF­κB pathway.

Lipoic acid (LA) exerts several beneficial effects including anti­inflammatory and antioxidant activity. This research aims to explore the function and mechanisms of LA on lipopolysaccharide (LPS)­induced PC12 cells. PC12 cells stimulated by LPS were used to mimic an in vitro inflammatory model of Parkinson's disease. Cell toxicity was determined by a cell counting kit­8 assay after various treatments. The concentrations of tumor necrosis factor (TNF-α), interleukin (IL)­1ß and IL­6 were analyzed by an ELISA kit. The effects of LA on cell apoptosis and cell cycle were measured by flow cytometry. The levels of α­syn, Nurr1 and tyrosine hydroxylase (TH) were tested by immunocytochemistry and ELISA kits. Western blotting assays were used to measure the expression of NF­κB pathway­related proteins. In PC12 cells, 100 µmol/mL LA effectively attenuated the upregulation of TNF­α, IL­1ß and IL­6 triggered by LPS; inhibited the increase of cell apoptosis; and relieved the cell cycle arrest induced. Additionally, the increase in α­syn and the decrease in Nurr1 and TH triggered by LPS were reversed by 100 µmol/mL LA. We also found that the elevated expression of p53 in LPS­induced PC12 cells was suppressed by LA. Significantly, knockdown of p53 enhanced the ameliorative effect of LA on LPS­triggered PC12 cell damage. The increase in levels of p­p65 NF­κB and p­IκBα triggered by LPS were suppressed by LA and si­p53 combination treatment. The results indicate that LA can attenuate LPS­triggered inflammation and apoptosis in PC12 cells by targeting the p53/NF­κB pathway. These findings provide a theoretical basis for the future treatment of inflammation in Parkinson's disease.

[Effects of probiotics on intestinal bacterial colonization in premature infants].

OBJECTIVE: To study the possible roles of probiotics in decreasing intestinal bacterial colonization rate and the incidence of enterogenic infections in premature infants. METHODS: Seventy premature infants were randomly assigned to two groups: probiotics and conventional treatment groups (control) (n=35 each). The probiotics treatment group was administered with oral Clostridium butyricum powder (250 mg, twice daily up to discharge) 24 hrs after birth except conventional treatment. Rectal swab cultures were done at admission, 5 and 12 days after admission, and before discharge. Clinical and laboratory findings were compared between the two groups. RESULTS: The intestinal bacterial colonization rate in the probiotics treatment group was lower than that in the control group 12 days after admission (60% vs 83%; p<0.05) and before discharge (51% vs 80%; p<0.05). Klebsiella pneumoniae, Escherichia coli and Enterococcus faecium were common colonization bacteria in the two groups. Diarrhea occurred in 7 cases (20%) in the probiotics treatment group compared with 16 cases (46%) in the control group (p<0.05). Two infants (6%) developed sepsis in the probiotics treatment group compared with 9 cases (26%) in the control group (p<0.05). CONCLUSIONS: Probiotics can decrease intestinal bacterial colonization rate and the incidence of diarrhea and sepsis in premature infants.

Translocase of the Outer Mitochondrial Membrane 40 Is Required for Mitochondrial Biogenesis and Embryo Development in Arabidopsis.

In eukaryotes, mitochondrion is an essential organelle which is surrounded by a double membrane system, including the outer membrane, intermembrane space and the inner membrane. The translocase of the outer mitochondrial membrane (TOM) complex has attracted enormous interest for its role in importing the preprotein from the cytoplasm into the mitochondrion. However, little is understood about the potential biological function of the TOM complex in Arabidopsis. The aim of the present study was to investigate how AtTOM40, a gene encoding the core subunit of the TOM complex, works in Arabidopsis. As a result, we found that lack of AtTOM40 disturbed embryo development and its pattern formation after the globular embryo stage, and finally caused albino ovules and seed abortion at the ratio of a quarter in the homozygous tom40 plants. Further investigation demonstrated that AtTOM40 is wildly expressed in different tissues, especially in cotyledons primordium during Arabidopsis embryogenesis. Moreover, we confirmed that the encoded protein AtTOM40 is localized in mitochondrion, and the observation of the ultrastructure revealed that mitochondrion biogenesis was impaired in tom40-1 embryo cells. Quantitative real-time PCR was utilized to determine the expression of genes encoding outer mitochondrial membrane proteins in the homozygous tom40-1 mutant embryos, including the genes known to be involved in import, assembly and transport of mitochondrial proteins, and the results demonstrated that most of the gene expressions were abnormal. Similarly, the expression of genes relevant to embryo development and pattern formation, such as SAM (shoot apical meristem), cotyledon, vascular primordium and hypophysis, was also affected in homozygous tom40-1 mutant embryos. Taken together, we draw the conclusion that the AtTOM40 gene is essential for the normal structure of the mitochondrion, and participates in early embryo development and pattern formation through maintaining the biogenesis of mitochondria. The findings of this study may provide new insight into the biological function of the TOM40 subunit in higher plants.

[Effect of different blood pressure control targets within 48 h after hypertensive cerebral hemorrhage on hematoma enlargement and prognosis].

OBJECTIVE: To study the effect of different blood pressure control targets on hematoma enlargement and prognosis in patients within 48 h after hypertensive cerebral hemorrhage (HCH). METHODS: Between January, 2013 and July, 2016, 102 patients with HCH were randomized into group A (51 cases) and group B (51 cases) with different systolic blood pressure (SBP) control targets within 48 h. The patients in group A were given early active antihypertensive treatment with SBP control target of 130-140 mm Hg; those in group B received standard antihypertensive treatment with SBP control target of 170-180 mm Hg. The changes in the volume of hematomas and the patients' prognosis were compared between the two groups. RESULTS: After 48 h of treatment, SBP, hematoma volume and the National Institutes of Health Stroke Scale (NIHSS) score were significantly lower and Glasgou Coma Scale (GCS) score was significantly higher in group A than in group B (P<0.01 or 0.05). After 30 days of treatment, the patients in group A showed significantly better indicators of treatment efficacy than those in group B (Z=2.331, P=0.020). The mortality rate was lower in group A than in group B, but the difference was not statistically significant (Χ2=2.772, P=0.096). CONCLUSION: Early active antihypertensive treatment is safe and feasible in patients with HCH and can reduce the enlargement of the hematomas, alleviate deterioration of neurological function, and improve the prognosis of the patients.

Basilar artery bending length, vascular risk factors, and pontine infarction.

BACKGROUND: Patients exhibiting basilar artery (BA) curvature (not dolichoectasia) are at an increased risk of posterior circulation ischemic stroke. In this study, pontine infarction patients were analyzed to assess the effect of BA bending length (BL) together with other vascular factors on pontine stroke risk. METHODS: Acute pontine infarction patients were divided into BA bending and non-BA bending groups by magnetic resonance angiography (MRA). Patients with BA bending who reported symptoms of dizziness or vertigo but who had not suffered brain infarction constituted the control group. The diameter of the vertebral artery (VA) and BL were measured using MRA. Based on the bilateral VA diameter data in vertebral artery-dominant (VAD) patients, the study participants were divided into three classes for VA diameter: class one, 0.30-0.80 mm (20 cases); class two, 0.81-1.37 mm (20 cases); and class three, 1.38-3.24 mm (20 cases). The measured BL in VAD cases allowed division of patients into three levels for BL: level one, 1.02-2.68 mm (21 cases); level two, 2.69-3.76 mm (20 cases); and level three, 3.77-7.25 mm (19 cases). Vascular risk factors were compared among the three groups. Correlations of BL and VA diameter differences were studied, and multivariate analysis was applied to search for predictors of ischemic stroke in BA bending patients. RESULTS: Among BA bending, non-BA bending, and control groups, VA dominance (VAD) proved to be a significant differentiator. For all three groups, a patient age of ≥ 65 years, the occurrence of hypertension, smoking, high homocysteine levels, high cholesterol, and a history of type 2 diabetes, were all statistically significant factors (P<0.05). After adjusting for other relevant factors, multivariate analysis shows that BL of level 3 was an independent risk factor for pontine infarction (OR=2.74; 95% CI, 1.27 to 4.48). Both BL and diameter differences between the VAs were positively correlated with risk with statistical significance (r=0.769, P<0.001). CONCLUSIONS: Both BL and diameter differences between the VAs are positively correlated with the risk of pontine infarction. When BA bending was coupled with other vascular risk factors, the probability of pontine infarction increased. BA bending with a BL greater than 3.77 mm was an independent predictor of pontine infarction.