Special architecture and anti-wear strategies for giant panda tooth enamel: Based on wear simulation findings.

Giant pandas are the flagship species in world conservation. Due to bamboo being the primary food source for giant pandas, dental wear is common owing to the extreme toughness of the bamboo fiber. Even though research on tooth enamel wear in humans and domestic animals is well-established, research on tooth enamel wear in giant pandas is scarce. The purpose of this study is to evaluate tooth enamel wear resistance in giant pandas to provide a basis for a better understanding of their evolutionary process. From microscopic and macroscopic perspectives, the abrasion resistance of dental enamel in giant pandas is compared with that of herbivorous cattle and carnivorous dogs in this study. This involves the use of micro-scratch and frictional wear tests. The results show that the boundary between the enamel prism and the enamel prism stroma is well-defined in panda and canine teeth, while bovine tooth enamel appears denser. Under constant load, the tribological properties of giant panda enamel are similar to those of canines and significantly different from those of bovines. Test results show that the depth of micro scratches in giant panda and canine enamel was greater than in cattle, with greater elastic recovery occurring in dogs. Scratch morphology indicates that the enamel substantive damage critical value is greater in pandas than in both dogs and cattle. The analysis suggests that giant panda enamel consists of a neatly arranged special structure that may disperse extrusion stress and absorb impact energy through a series of inelastic deformation mechanisms to cope with the wear caused by eating bamboo. In this study, the excellent wear resistance of giant panda's tooth enamel is verified by wear tests. A possible theoretical explanation of how the special structure of giant panda tooth enamel may improve its wear resistance is provided. This provides a direction for subsequent theoretical and experimental studies on giant panda tooth enamel and its biomaterials.

"Lest we forget": An overview of Australia's response to the recovery and identification of unrecovered historic military remains.

The Australian Defence Force (ADF) is responsible for the recovery and identification of its historic casualties. With over 30,000 still unrecovered from past conflicts including World War One (WW1) and World War Two (WWII), the Australian Army and Royal Australian Air Force have teams that research, recover, identify and oversee the burial (or reburial) of the remains of soldiers and airmen who continue to be found each year. The Royal Australian Navy is also responsible for its unrecovered casualties. Collectively the priorities of the various services within the ADF are the respectful recovery and treatment of the dead, thorough forensic identification efforts, resolution for families and honouring the ADF's proud history of service and sacrifice. What is unique about the approach of the ADF is that the respective services retain responsibility for their historic losses, while a joint approach is taken on policies and in the utilisation of the pool of forensic specialists. Section One describes the process undertaken by the Australian Army in the recovery, identification and burial or repatriation of soldiers through its specialised unit Unrecovered War Casualties - Army (UWC-A). Section Two describes the role of the Royal Australian Air Force in the recovery of aircraft and service personnel through their specialised unit Historic Unrecovered War Casualties - Air Force (HUWC-AF). An overview of the operations of each service and case studies is presented for each section.

Electrochemical cobalt-catalyzed C-H or N-H oxidation: a facile route to synthesis of substituted oxindoles.

Two comparable protocols for the electrochemical cobalt-catalyzed C-H/N-H oxidation have been exploited for the synthesis of substituted oxindoles via radical pathways. The electrochemical cobalt-catalyzed system was demonstrated to be efficient and eco-friendly and avoided the use of stoichiometric oxidants to afford the arylation or alkylation products in good yields at room temperature.

Improving the Signal-to-Background Ratio during Catalytic Hairpin Assembly through Both-End-Blocked DNAzyme.

Catalyzed hairpin assembly (CHA) is an important DNA engineering tool for a variety of applications such as DNA nanotechnology and biosensing. Here we report a hairpin-type of both-end-blocked DNAzyme to improve the signal-to-background ratio during the CHA process. In the design, the DNAzyme activity can be blocked efficiently via locking both ends of the G-rich DNAzyme sequence in the loop and stem (blocking efficiency = 96%) and can be easily recovered during the CHA process (activation efficiency = 94%). The both-end-blocked DNAzyme is by far the most sensitive optical detection mode for monitoring the CHA process that can be used for determination of 0.05 fmol miRNA-21. The fabricated CHA-DNAzyme sensing system was also able to discriminate miRNA-21 from single-/three-base mismatch miRNA-21. The feasibility of real application was also tested via detection of miRNA-21 levels in tumor cell samples. Therefore, the sensing system with the advantages of convenience, high sensitivity, and selectivity is an appealing strategy for miRNA detection.

One-Pot Regiospecific Synthesis of Indolizines: A Solvent-Free, Metal-Free, Three-Component Reaction of 2-(Pyridin-2-yl)acetates, Ynals, and Alcohols or Thiols.

A novel approach for the synthesis of indolizines from 2-(pyridin-2-yl)acetates, ynals, and alcohols or thiols has been developed. This MCR (multicomponent reaction) that proceeds under the solvent- and metal-free conditions has provided a straightforward path to construct indolizines. Furthermore, this reaction demonstrates other attractive features such as widely available starting materials, mild conditions, good functional group tolerance, and high efficiency.

Replication of hepatitis E virus in the ovary and promotion of oocyte apoptosis in rabbits infected with HEV-4.

Hepatitis E virus (HEV) infection can induce infertility and miscarriage in pregnant women and infect neonates through vertical transmission. However, the mechanism of infertility and vertical transmission remains unclear. In the present study, we evaluated the replication of HEV in the ovary and structural and molecular changes induced by HEV after intraperitoneal injection of HEV in rabbits. Positive- and negative-strand HEV RNA was detected in the ovaries at 28 and 49 days post-infection. Positive HEV open reading frames 2 and 3 signals were observed in the ovaries by immunohistochemistry staining. Histopathological changes of ovarian tissues were observed, including scattered cell necrosis and lymphocyte infiltration. The ratio of normal follicles decreased, whereas the ratio of atresia follicles increased in the HEV RNA-positive ovaries compared to the control group by counting the number of follicles at all levels. In addition, TUNEL results showed that apoptosis in follicle cells and oocytes was promoted by HEV infection. These results suggest that the ovary is one of the replication sites of HEV and that the expression of HEV RNA and antigen in ovarian tissue caused structural and molecular changes that promoted germ cell apoptosis. HEV can infect and replicate in the ovum at different stages, which is a novel mechanism for HEV vertical transmission.

Transition-metal-free regioselective C-H halogenation of imidazo[1,2-a]pyridines: sodium chlorite/bromite as the halogen source.

A facile transition-metal-free regioselective halogenation of imidazo[1,2-a]pyridines using sodium chlorite/bromite as the halogen source is presented. The reaction has provided an efficient method for the formation of C-Cl or C-Br bonds to synthesize 3-chloro or 3-bromo-imidazo[1,2-a]pyridines which were then efficiently transformed into imidazo[1,2-a]pyridine core π-systems by Suzuki-Miyaura reactions.

Substrate-Controlled Selectivity Switch in a Three-Component Reaction: A Ag-Catalyzed Strategy for the Synthesis of Functionalized Imidazoles.

An efficient Ag-catalyzed three-component reaction of amidines, ynals, and alcohols, phenols, or water has been developed. This strategy provides a wide range of substrates and represents a simple process for the preparation of different imidazole derivatives in good yields with high regioselectivities.

Analysis of lifespan-promoting effect of garlic extract by an integrated metabolo-proteomics approach.

The beneficial effects of garlic (Allium sativum) consumption in treating human diseases have been reported worldwide over a long period of human history. The strong antioxidant effect of garlic extract (GE) has also recently been claimed to prevent cancer, thrombus formation, cardiovascular disease and some age-related maladies. Using Caenorhabditis elegans as a model organism, aqueous GE was herein shown to increase the expression of longevity-related FOXO transcription factor daf-16 and extend lifespan by 20%. By employing microarray and proteomics analysis on C. elegans treated with aqueous GE, we have systematically mapped 229 genes and 46 proteins with differential expression profiles, which included many metabolic enzymes and yolky egg vitellogenins. To investigate the garlic components functionally involved in longevity, an integrated metabolo-proteomics approach was employed to identify metabolites and protein components associated with treatment of aqueous GE. Among potential lifespan-promoting substances, mannose-binding lectin and N-acetylcysteine were found to increase daf-16 expression. Our study points to the fact that the lifespan-promoting effect of aqueous GE may entail the DAF-16-mediated signaling pathway. The result also highlights the utility of metabolo-proteomics for unraveling the complexity and intricacy involved in the metabolism of natural products in vivo.

Comparative proteomics analysis of degenerative eye lenses of nocturnal rice eel and catfish as compared to diurnal zebrafish.

PURPOSE: The aim of this study was to determine the lens crystallin diversity of degenerative eyes from the rice eel (Monopterus albus) and walking catfish (Clarias batrachus) as compared to that of zebrafish (Danio rerio) by using comparative proteomics methodologies. We endeavored to investigate the evolution of vertebrate lenses particularly concerning the functional loss of lenses in degenerative eyes of rice eels and catfishes living under an environment of perpetual darkness. METHODS: Fish lenses were collected and homogenized to extract total soluble proteins. The protein mixtures were separated by one- and two-dimensional gel electrophoresis (1D or 2D gel), plus the newer gel-free shotgun proteomic strategy, followed by in-gel digestion and subjection of the digested protein bands or spots to liquid chromatography coupled with tandem mass spectrometry. The proteomics data were analyzed and compared based on the proteomics databank of zebrafish. The soluble lens protein solutions of three piscine species were also processed by gel-filtration chromatography and 1D sodium dodecyl sulfate-polyacrylamide gel electrophoresis for the comparison and validation of various crystallin families, e.g., α-, ß-, and γ-crystallins. RESULTS: In zebrafish eye lenses, γ-crystallin constituted about 71% and α- and ß-crystallins comprised 30% of total lens proteins. In rice eel lenses, very little or almost no α-crystallins were detected and ß- and γ-crystallins comprised more than 98% of total lens proteins. In catfish lenses, α- and ß-crystallins comprised about 40% and γ-crystallin constitutes 60% of total lens proteins. It was of interest to find that α-crystallin was totally absent in the rice eel in contrast to the presence, albeit with very low amounts, of α-crystallin in similarly nocturnal catfish. The ratio of α-crystallin subunits (αA/αB) was found to be about 20:1 for the catfish lens, in great contrast to the ratio of about 3:1 found for most mammalian lenses. In contrast, ß- and γ-crystallins were more abundant in lenses of these three piscine species, similar to mammalian lenses. By proteomics analysis, the most abundant ß-crystallins were found to comprise a diverse group of ßA1a, ßA1-2, ßA2a, ßA2-2, ßA4, ßB1, ßB2, and ßB3 subunit crystallins; the monomeric γ-crystallin class contains γB, γD, γM2, γM3, γM5, γM7, γN-A, γN-B, γS1, and γS2 crystallins. CONCLUSIONS: In cave or nocturnal animals, the eye is sometimes reduced or eliminated because of adaptation to life in visual darkness. The comparative proteomics analysis of degenerative and normal lenses forms a firm molecular basis to investigate further the evolution of piscine lenses in the future. The total numbers of α-, ß-, and γ-crystallins in the three fish species as revealed by the current proteomics methodology clearly indicate the complexity and diversity of crystallin species present in the piscine class of vertebrates. The unexpected finding that α-crystallin is absent in the degenerative eye lenses of rice eel may have some bearing on the chaperone function of α-crystallin in regard to its protective role of preventing protein aggregation in diurnal vertebrate lenses to maintain functional transparency.

Alkylhydroperoxide reductase of Helicobacter pylori as a biomarker for gastric patients with different pathological manifestations.

The development of various gastrointestinal diseases was suggested to be associated with chronic inflammation as a consequence of Helicobacter pylori (H. pylori) infection. Our previous studies showed that an antioxidant protein alkylhydroperoxide reductase (AhpC) is an abundant and important antioxidant protein present in H. pylori. In this study we have explored the potential of utilizing antibodies to AhpC for detection of patients who are at high risks of evolving into severe outcomes of gastric malignancies after H. pylori infection. The correlation between AhpC and extents of inflammatory damage in tissues was demonstrated by immunoblotting assays and endoscopic examinations. Oxidative stress-induced high-molecular-weight (HMW) AhpC with chaperone activity in vivo was further investigated by co-immunoprecipitation, 2-dimensional gel electrophoresis (2-DE) followed by nano-liquid chromatography coupled tandem mass spectrometry (nanoLC-MS/MS). We found AhpC was consistently expressed in higher amounts in H. pylori strains isolated from patients with gastric cancer (GC) than gastritis (GA). Immunological analysis of seropositivity for AhpC indicated that positive diagnostic rates for H. pylori-infected patients with GA, gastric ulcer (GU) and GC were 68% (15/22), 100% (50/50) and 100% (50/50), respectively. In great contrast to low-molecular-weight (LMW) AhpC, HMW AhpC with chaperone function was found to distribute inside of H. pylori cells. We also found that LMW forms of AhpC were recognized by serum antibodies from GA patients whereas HMW forms of AhpC reacted mainly with those from GU and GC patients. Based on the significant difference between AhpC isolated from strains of GC and GA, it is conceivable that AhpC of H. pylori may prove to be useful as a prognostic or diagnostic protein marker to monitor varied clinical manifestations of gastrointestinal patients infected with H. pylori.

Characterization of site-specific mutants of alkylhydroperoxide reductase with dual functionality from Helicobacter pylori.

Alkylhydroperoxide reductase (AhpC) is an abundant and important antioxidant protein present in Helicobacter pylori (HP), a spiral Gram-negative microaerophilic bacterium. By sequence alignment and structure comparison, HP-AhpC was found to be more homologous to human peroxiredoxins (hPrx) than to other eubacterial AhpC proteins. Similar to hPrxI, native HP-AhpC existed as a dimer of single subunit, comprising alpha-helix and beta-sheet domains with low surface hydrophobicity. AhpC can form high-molecular-weight (HMW) aggregates ranging from 700 to higher than 2,000 kDa under oxidative stress, possessing chaperone activity in the presence of thioredoxin (Trx). Further analysis of peroxide-reductase activities showed that HP-AhpC was more resistant to H(2)O(2) than hPrxI. However, the mechanism of enzyme inactivation to H(2)O(2) appeared to be similar for both HP-AhpC and hPrxI as revealed by native gel electrophoresis followed by proteomic identification using two-dimensional gel electrophoresis (2-DE) and LC-MS/MS. In contrast to T90D-hPrxI mutant with chaperone activity, site-specific mutant T87D-HP-AhpC did not form HMW chaperone complexes. The comparison of these two evolutionarily distant and yet functionally related enzymes may shed some light on the mechanism(s) underlying the evolution and development of the dual functionality in HP-AhpC and hPrxI with similar protein structure.