Regulation of progesterone during follicular development by FSH and LH in sheep

Progesterone (P4) can participate in the development of female mammalian antral follicles through nuclear receptor (PGR). In this experiment, the differences of P4 synthesis and PGR expression in different developmental stages of sheep antral follicles (large > 5mm, medium 2-5mm, small < 2mm) were detected by enzyme-linked immunosorbent assay, immunohistochemistry, qRT-PCR and Western blotting. Secondly, sheep follicular granulosa cells were cultured in vitro. The effects of different concentrations of FSH and LH on P4 synthesis and PGR expression were studied. The results showed that acute steroid regulatory protein (StAR), cholesterol side chain lyase (P450scc) and 3β Hydroxysteroid dehydrogenase (3β-HSD) and PGR were expressed in antral follicles, and with the development of antral follicles in sheep, StAR, P450scc and the expression of 3β-HSD and PGR increased significantly. In vitro experiments showed that FSH and LH alone or together treatment could regulate P4 secretion and PGR expression in sheep follicular granulosa cells to varying degrees, hint P4 and PGR by FSH and LH, and LH was the main factor. Our results supplement the effects of FSH and LH on the regulation of P4 synthesis during follicular development, which provides new data for further study of steroid synthesis and function in follicular development.     

Structure and Specificity of the Bacterial Cysteine Methyltransferase Effector NleE Suggests a Novel Substrate in Human DNA Repair Pathway

Enteropathogenic E. coli (EPEC) and related enterobacteria rely on a type III secretion system (T3SS) effector NleE to block host NF-κB signaling. NleE is a first in class, novel S-adenosyl-L-methionine (SAM)-dependent methyltransferase that methylates a zinc-coordinating cysteine in the Npl4-like Zinc Finger (NZF) domains in TAB2/3 adaptors in the NF-κB pathway, but its mechanism of action and other human substrates are unknown. Here we solve crystal structure of NleE-SAM complex, which reveals a methyltransferase fold different from those of known ones. The SAM, cradled snugly at the bottom of a deep and narrow cavity, adopts a unique conformation ready for nucleophilic attack by the methyl acceptor. The substrate NZF domain can be well docked into the cavity, and molecular dynamic simulation indicates that Cys673 in TAB2-NZF is spatially and energetically favorable for attacking the SAM. We further identify a new NleE substrate, ZRANB3, that functions in PCNA binding and remodeling of stalled replication forks at the DNA damage sites. Specific inactivation of the NZF domain in ZRANB3 by NleE offers a unique opportunity to suggest that ZRANB3-NZF domain functions in DNA repair processes other than ZRANB3 recruitment to DNA damage sites. Our analyses suggest a novel and unexpected link between EPEC infection, virulence proteins and genome integrity.     

Soil carbon fractions in grasslands respond differently to various levels of nitrogen enrichments

Background and Aims

Soil contains many different C fractions which have diverse physical and chemical compositions. Examining these differential soil C fractions in response to N enrichment is helpful for better understanding soil C changes under the predominantly increasing N deposition. In this study, we used a field N addition experiment in a grassland to explore the effects of various N enrichment levels on soil C fractions.

Methods

We conducted a field manipulative experiment which used a Latin square design with six N addition levels of 0, 2, 4, 8, 16 and 32 g N m^?2 year^?1 since 2003 in a semiarid grassland in northern China. Soil samples were collected in August (when plants have the greatest biomass), 2011. We measured C and N concentrations in soil light fraction, microbial biomass, extractable organic matter, heavy fraction, and total soil C and N.

Results

The results showed that total soil C and N, and heavy fraction C and N were not significantly affected by N addition after 9 years of treatments. In contrast, different N enrichment levels changed soil light fraction C and N, ranging from 4.3 to 27.7 % and 3.3–30.0 %, respectively. Moreover, both light fraction C and N had a nonlinear relationship with N addition rates, and the threshold for N-induced change in light fraction C and N was near 16 g N m^?2 year^?1 in this semiarid grassland. Increases of soil light fraction C and N primarily resulted from changes in biotic (N-stimulated aboveground biomass) and abiotic (soil temperature, moisture and pH) factors under N enrichment. Soil microbial biomass exponentially declined with increasing N, but extractable organic C showed a positive linear response to N enrichment rates. Changes in microbial biomass C and extractable organic C were primarily due to the reduced soil pH under N addition.

Conclusions

Our findings suggest that various soil C fractions differentially respond to elevated N, because different sets of biotic and abiotic factors regulate those fractions under N enrichment.     

Overexpression of Aurora-A enhances invasion and matrix metalloproteinase-2 expression in esophageal squamous cell carcinoma cells

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive cancers, and metastasis is the principal cause of death in ESCC patients. It has been shown that amplification and overexpression of mitotic serine/threonine kinase Aurora-A occur in several types of human tumors, including ESCC. Moreover, increase in expression levels of Aurora-A has been predicted to correlate with the grades of tumor differentiation and invasive capability. However, the mechanisms by which Aurora-A mediates its invasive effects still remain elusive. In this article, we showed that Aurora-A overexpression significantly increased cell migration and invasion as well as secretion and expression of matrix metalloproteinase-2 (MMP-2). Conversely, siRNA-mediated knockdown of Aurora-A expression in human ESCC cells led to inhibition of cell invasiveness as well as secretion and expression of MMP-2. In addition, Aurora-A overexpression increased phosphorylation levels of p38 mitogen-activated protein kinase (MAPK) and Akt, and the knockdown of Aurora-A by siRNA decreased the activity of p38 MAPK and Akt. Moreover, the blocking of the activity of above kinases using chemical inhibitors suppressed the ability of Aurora-A to induce MMP-2 secretion and expression as well as cell invasion. These data show that overexpression of Aurora-A contributes to the malignancy development of ESCC by enhancing tumor cell invasion as well as MMP-2 activity and expression, which can occur through signaling pathways involving p38 MAPK and Akt protein kinases. Taken together, these studies provide a molecular basis for promoting the role of Aurora-A in malignancy development of ESCC.     

Cell origins and diagnostic accuracy of interleukin 27 in pleural effusions

The objective of the present study was to investigate the presence of interleukin (IL)-27 in pleural effusions and to evaluate the diagnostic significance of pleural IL-27. The concentrations of IL-27 were determined in pleural fluids and sera from 68 patients with tuberculous pleural effusion, 63 malignant pleural effusion, 22 infectious pleural effusion, and 21 transudative pleural effusion. Flow cytometry was used to identify which pleural cell types expressed IL-27. It was found that the concentrations of pleural IL-27 in tuberculous group were significantly higher than those in malignant, infectious, and transudative groups, respectively. Pleural CD4(+) T cells, CD8(+) T cells, NK cells, NKT cells, B cells, monocytes, macrophages, and mesothelial cells might be the cell sources for IL-27. IL-27 levels could be used for diagnostic purpose for tuberculous pleural effusion, with the cut off value of 1,007 ng/L, IL-27 had a sensitivity of 92.7% and specificity of 99.1% for differential diagnosing tuberculous pleural effusion from non-tuberculous pleural effusions. Therefore, compared to non-tuberculous pleural effusions, IL-27 appeared to be increased in tuberculous pleural effusion. IL-27 in pleural fluid is a sensitive and specific biomarker for the differential diagnosing tuberculous pleural effusion from pleural effusions with the other causes.     

Oxidative stress causes a decline in lysosomal integrity during hypothermic incubation of rat hepatocytes

Oxidative stress during cold preservation has been identified as a significant cause of cell injury but the process by which injury occurs is poorly understood. We examined loss of lysosomal integrity as a possible cause of cell injury during extended cold storage of isolated rat hepatocytes. After 21 h of hypothermia, there was a marked decline in lysosomal integrity, which was correlated with an increase in lipid peroxidation. When lipid peroxidation was prevented with the antioxidant Trolox (a vitamin E analog) or the iron chelator desferrioxamine, lysosomal integrity was preserved. In contrast, increasing lysosomal iron with ferric chloride caused an increase in lipid peroxidation and decreased lysosomal integrity. Loss of lysosomal integrity during cold preservation in this experimental model was consistent with iron-initiated oxidative stress. The progressive loss of lysosomal integrity during hypothermic incubation has the potential to affect liver function after transplantation.     

Anti-adhesive Property of Maize Leaf Surface Related with Temperature and Humidity

The anti-adhesive surfaces have always aroused great interest of worldwide scientists and engineers.But in practical applications,it often faces the threat and impact of temperature and humidity.In this work,the excellent anti-adhesive performance of maize leaf under high temperature and humidity were investigated in detail.Firstly,the adhesion forces of the maize leaf surface under different temperature and humidity were measured by using Atomic Force Microscopy (AFM).The temperature of the substrate was varied between 23 ℃ to 100 ℃,and the ambient relative humidity is from 18％ to 100％.It was found that the adhesion force of maize leaf decreased with the increase of temperature and humidity.The mechanism of its excellent anti-adhesive performance of maize leaf under high temperature and relative humidity was revealed.The transverse and longitudinal ridges on maize leaf surface interlace with each other,forming small air pockets,which reduces the actual contact area between the object and the maize leaf.With the increase of humidity,the liquid film will be formed in the air pockets gradually and so much water vapor is produced with increase of temperature.Then the air flow rate increases though the wavy top of transverse ridges,inducing the dramatic decrease of adhesion force.Inspired by this mechanism,four samples with this bionic structure were made.This functional "biomimetic structure" would have potential value in the wide medical equipments such as high frequency electric knife with anti-adhesion surface under high temperature and high humidity.