MKK3 Was Involved in Larval Settlement of the Barnacle Amphibalanus amphitrite through Activating the Kinase Activity of p38MAPK

The p38 mitogen-activated protein kinase (p38MAPK) plays a key role in larval settlement of the barnacle Amphibalanus amphitrite. To study the signaling pathway associated with p38MAPK during larval settlement, we sought to identify the upstream kinase of p38MAPK. Three MKKs (MKK3, MKK4 and MKK7) and three MAPKs (p38MAPK, ERK and JNK) in A. amphitrite were cloned and recombinantly expressed in E. coli. Through kinase assays, we found that MKK3, but not MKK4 or MKK7, phosphorylated p38MAPK. Furthermore, MKK3 activity was specific to p38MAPK, as it did not phosphorylate ERK or JNK. To further investigate the functional relationship between MKK3 and p38MAPK in vivo, we studied the localization of phospho-MKK3 (pMKK3) and MKK3 by immunostaining. Consistent with the patterns of p38MAPK and phospho-p38MAPK (pp38MAPK), pMKK3 and MKK3 mainly localized to the antennules of the cyprids. Western blot analysis revealed that pMKK3 levels, like pp38MAPK levels, were elevated at cyprid stage, compared to nauplii and juvenile stages. Moreover, pMKK3 levels increased after treatment with adult barnacle crude extracts, suggesting that MKK3 might mediate the stimulatory effects of adult barnacle extracts on the p38MAPK pathway.     

The ING4 Binding with p53 and Induced p53 Acetylation were Attenuated by Human Papillomavirus 16 E6

High risk subtype HPV16 early oncoprotein E6 contributes host cell immortalization and transformation through interacting with a number of cellular factors. ING4 is one member of the inhibitor of growth (ING) family of type II tumor suppressors and it has been shown to be involved in regulating p53 function. However, the effect and mechanism of HPV16 E6 on ING4 function remain elusive. In this study, we report HPV16 E6 combines with ING4 in vivo and in vitro. The ING4 induced p53 acetylation and its combining with p53 were attenuated by HPV16 E6 independent of p53 degradation. The enhancing function of ING4 on p53 mediated apoptosis was diminished when HPV16 E6 existed. These findings reveal that ING4 may be a common target of oncogenic viruses for driving host cell carcinogenesis.     

Insulin Promotes Glucose Consumption via Regulation of miR-99a/mTOR/PKM2 Pathway

Insulin is known to regulate multiple cellular functions and is used for the treatment of diabetes. MicroRNAs have been demonstrated to be involved in many human diseases, including Type 2 diabetes. In this study, we showed that insulin decreased miR-99a expression levels, but induced glucose consumption and lactate production, and increased the expression of mTOR, HIF-1α and PKM2 in HepG2 and HL7702 cells. Forced expression of miR-99a or rapamycin treatment blocked insulin-induced PKM2 and HIF-1α expression, and glucose consumption and lactate production. Meanwhile, knockdown of HIF-1α inhibited PKM2 expression and insulin-induced glucose consumption. Taken together, these findings will reveal the role and mechanism ofinsulin in regulating glycolytic activities via miR-99a/mTOR.     

Phospholipid Metabolism in an Industry Microalga Chlorella sorokiniana: The Impact of Inoculum Sizes

Chlorella sorokiniana is an important industry microalga potential for biofuel production. Inoculum size is one of the important factors in algal large-scale culture, and has great effects on the growth, lipid accumulation and metabolism of microalgae. As the first barrier of cell contents, membrane plays a vital role in algal inoculum-related metabolism. The knowledge of phospholipids, the main membrane component and high accumulation of phospholipids as the major content of total lipids mass in some microalgae, is necessary to understand the role of membrane in cell growth and metabolism under different inoculum density. Profiling of C. sorokiniana phospholipids with LC-MS led to the identification of 119 phospholipid species. To discover the phospholipid molecules most related to change of inoculum sizes, Partial Least Squares Discriminant Analysis (PLS-DA) was employed and the results revealed that inoculum sizes significantly affected phospholipid profiling. Phosphatidylglycerol (PG), phosphatidyl- ethanolamine (PE) and several phosphatidylcholine (PC) species might play an important role under our experimental conditions. Further analysis of these biomarkers indicated that cell membrane status of C. sorokiniana might play an important role in the adaption to the inoculum sizes. And the culture with inoculum size of 1×10⁶ cells mL⁻¹ presented the best membrane status with the highest content of PC and PG, and the lowest content of PE. We discovered that the inoculum size of 1×10⁶ cells mL⁻¹ might provide the best growth condition for C. sorokiniana. Also we proposed that PG, PE and several PC may play an important role in inoculum-related metabolism in C. sorokiniana, which may work through thylakoid membrane and photosynthetic pathway. Thus this study would provide more potential targets for metabolic engineering to improve biofuel production and productivity in microalgae.     

The G0/G1 Switch Gene 2 Is an Important Regulator of Hepatic Triglyceride Metabolism

Nonalcoholic fatty liver disease is associated with obesity and insulin resistance. Factors that regulate the disposal of hepatic triglycerides contribute to the development of hepatic steatosis. G₀/G₁ switch gene 2 (G0S2) is a target of peroxisome proliferator-activated receptors and plays an important role in regulating lipolysis in adipocytes. Therefore, we investigated whether G0S2 plays a role in hepatic lipid metabolism. Adenovirus-mediated expression of G0S2 (Ad-G0S2) potently induced fatty liver in mice. The liver mass of Ad-G0S2-infected mice was markedly increased with excess triglyceride content compared to the control mice. G0S2 did not change cellular cholesterol levels in hepatocytes. G0S2 was found to be co-localized with adipose triglyceride lipase at the surface of lipid droplets. Hepatic G0S2 overexpression resulted in an increase in plasma Low-density lipoprotein (LDL)/Very-Low-density (VLDL) lipoprotein cholesterol level. Plasma High-density lipoprotein (HDL) cholesterol and ketone body levels were slightly decreased in Ad-G0S2 injected mice. G0S2 also increased the accumulation of neutral lipids in cultured HepG2 and L02 cells. However, G0S2 overexpression in the liver significantly improved glucose tolerance in mice. Livers expressing G0S2 exhibited increased 6-(N-(7-nitrobenz-2-oxa-1-3-diazol-4-yl) amino)-6-deoxyglucose uptake compared with livers transfected with control adenovirus. Taken together, our results provide evidence supporting an important role for G0S2 as a regulator of triglyceride content in the liver and suggest that G0S2 may be a molecular target for the treatment of insulin resistance and other obesity-related metabolic disorders.     

Noise Exposure and Hearing Impairment among Chinese Restaurant Workers and Entertainment Employees in Hong Kong

Background

Noise-induced hearing loss (NIHL) is a major concern in the non-manufacturing industries. This study aimed to investigate the occupational noise exposure and the NIHL among Chinese restaurant workers and entertainment employees working in the service industry in Hong Kong.

Methods

This cross-sectional survey involved a total of 1,670 participants. Among them, 937 were randomly selected from the workers of Chinese restaurants and 733 were selected from workers in three entertainment sectors: radio and television stations; cultural performance halls or auditoria of the Leisure and Cultural Services Department (LCSD); and karaoke bars. Noise exposure levels were measured in the sampled restaurants and entertainment sectors. Each participant received an audiometric screening test. Those who were found to have abnormalities were required to take another diagnostic test in the health center. The “Klockhoff digit” method was used to classify NIHL in the present study.

Results

The main source of noise inside restaurants was the stoves. The mean hearing thresholds showed a typical dip at 3 to 6 KHz and a substantial proportion (23.7%) of the workers fulfilled the criteria for presumptive NIHL. For entertainment sectors, employees in radio and television stations generally had higher exposure levels than those in the halls or auditoria of the LCSD and karaoke bars. The mean hearing thresholds showed a typical dip at 6 KHz and a substantial proportion of the employees fulfilled the criteria for presumptive NIHL (38.6%, 95%CI: 35.1–42.1%). Being male, older, and having longer service and daily alcohol consumption were associated with noise-induced hearing impairment both in restaurant workers and entertainment employees.

Conclusion

Excessive noise exposure is common in the Chinese restaurant and entertainment industries and a substantial proportion of restaurant workers and entertainment employees suffer from NIHL. Comprehensive hearing conservation programs should be introduced to the service industry in Hong Kong.     

SCD1 promotes lipid mobilization in subcutaneous white adipose tissue

Beiging of white adipose tissue (WAT) has beneficial effects on metabolism. Although it is known that beige adipocytes are active in lipid catabolism and thermogenesis, how they are regulated deserves more explorations. In this study, we demonstrate that stearoyl-CoA desaturase 1 (SCD1) in subcutaneous WAT (scWAT) responded to cold stimulation and was able to promote mobilization of triacylglycerol [TAG (triglyceride)]. In vitro studies showed that SCD1 promoted lipolysis in C3H10T1/2 white adipocytes. The lipolytic effect was contributed by one of SCD1’s products, oleic acid (OA). OA upregulated adipose TAG lipase and hormone-sensitive lipase expression. When SCD1 was overexpressed in the scWAT of mice, lipolysis was enhanced, and oxygen consumption and heat generation were increased. These effects were also demonstrated by the SCD1 knockdown experiments in mice. In conclusion, our study suggests that SCD1, known as an enzyme for lipid synthesis, plays a role in upregulating lipid mobilization through its desaturation product, OA.     

Dietary adaptations and palaeoecology of Lophialetidae (Mammalia,Tapiroidea) from the Eocene of the Erlian Basin,China: combined evidence from mesowear and stable isotope analyses

Lophialetidae is an extinct group of endemic Asiatic tapiroids that are widely distributed in the Eocene sediments of Asia. Schlosseria magister and Lophialetes expeditus are the most abundant species in this family. However, their dietary and ecological characteristics are largely unknown. For the first time, we reconstruct the palaeodiet and habitat of these two lophialetids using a combination of mesowear and stable carbon isotope analysis of fossil teeth excavated from the Erlian Basin, China. Mesowear analysis (n = 141) suggests that the dietary structure of S. magister and L. expeditus shifted from less to more abrasive diets from ~52 to ~42 Ma. Stable carbon isotope analysis (n = 137) suggests that the habitats of S. magister and L. expeditus became drier and/or more open through time. The dietary shifts of the two lophialetids are consistent with evident changes in habitat. The changes in the diet and habitat were probably related to global climate change during that time period. The gradual drop in global temperatures during the early–middle Eocene led to a drier and more open terrestrial ecosystem in the Erlian Basin, probably resulting in changes in floral composition of the environment inhabited by S. magister and L. expeditus. Hence, herbivores highly susceptible to vegetation modification had to develop new resource exploitation strategies to adapt to these changes. Schlosseria magister, considered to be the sister-group of L. expeditus and with a low level of ecological flexibility, was unable to adapt to the habitat changes finally becoming extinct at ~45 Ma.     

Selenium-Alleviated Hepatocyte Necrosis and DNA Damage in Cyclophosphamide-Treated Geese by Mitigating Oxidative Stress

Biological Trace Element Research - Selenium (Se) has been well recognized as an immune-enhancing agent with antioxidant and anti-tumor properties. The commonly used chemotherapy drug,...     

Relationship of Nitrogen Deficiency-Induced Leaf Senescence with ROS Generation and ABA Concentration in Rice Flag Leaves

Nitrogen (N) deficiency is one of the critical environmental factors that induce leaf senescence, and its occurrence may cause the shorten leaf photosynthetic period and markedly lowered grain yield. However, the physiological metabolism underlying N deficiency-induced leaf senescence and its relationship with the abscisic acid (ABA) concentration and reactive oxygen species (ROS) burst in leaf tissues are not well understood. In this paper, the effect of N supply on several senescence-related physiological parameters and its relation to the temporal patterns of ABA concentration and ROS accumulation during leaf senescence were investigated using the premature senescence of flag leaf mutant rice (psf) and its wild type under three N treatments. The results showed that N deficiency hastened the initiation and progression of leaf senescence, and this occurrence was closely associated with the upregulated expression of 9-cis-epoxycarotenoiddioxygenase genes (NCEDs) and with the downregulated expression of two ABA 8′-hydroxylase isoform genes (ABA8ox2 and ABA8ox3) under LN treatment. Contrarily, HN supply delayed the initiation and progression of leaf senescence, concurrently with the suppressed ABA biosynthesis and relatively lower level of ABA concentration in leaf tissues. Exogenous ABA incubation enhanced ROS generation and MDA accumulation in a dose-dependent manner, but it decreased the activities of glutamine synthetase (GS) and glutamate dehydrogenase (GDH) in detached leaf. These results suggested that the participation of ABA in the regulation of ROS generation and N assimilating/remobilizing metabolism in rice leaves was strongly responsible for induction of leaf senescence by N deficiency.