Overview of the biogenic sources of atmospheric trace compounds due to agricultural activities

All human activities profoundly affect the chemical composition and properties of the atmosphere. The present overview highlights the impact of agricultural practices, including livestock raising, on the biogeochemical cycles of carbon and nitrogen and discusses the relevant environmental issues. Emissions from agriculture significantly contribute to the atmospheric budget of methane and nitrous oxide, which in turn contribute to the greenhouse effect. Agricultural activities are also the predominant source of ammonia to the atmosphere, so affecting the acidity of atmospheric depositions. A minor role is expected from agriculture in the production of tropospheric ozone through nitrogen oxides and volatile organic compound emissions.     

Overview of the biogenic sources of atmospheric trace compounds due to agricultural activities

All human activities profoundly affect the chemical composition and properties of the atmosphere. The present overview highlights the impact of agricultural practices, including livestock raising, on the biogeochemical cycles of carbon and nitrogen and discusses the relevant environmental issues. Emissions from agriculture significantly contribute to the atmospheric budget of methane and nitrous oxide, which in turn contribute to the greenhouse effect. Agricultural activities are also the predominant source of ammonia to the atmosphere, so affecting the acidity of atmospheric depositions. A minor role is expected from agriculture in the production of tropospheric ozone through nitrogen oxides and volatile organic compound emissions.     

Geochemical constraints on the origin of organic compounds in hydrothermal systems

It is proposed that abiotic synthesis of organic compounds occurs in metastable states. These states are permitted by kinetic barriers which inhibit the approach to stable equilibrium in the C-H-O-N system. Evidence for metastable equilibrium among organic compounds in sedimentary basins is reviewed, and further evidence is elucidated from hydrous pyrolysis experiments reported in the literature. This analysis shows that at hydrothermal conditions, organic compounds are formed or destroyed primarily through oxidation/reduction reactions, and that the role of temperature is to lower the kinetic barriers to these reactions. These lines of evidence allow the development of a scenario in which abiotic synthesis can occur at hydrothermal conditions through the reduction of CO₂ and N₂. This scenario can be tested quantitatively with distribution of species calculations as functions of temperature, pressure, hydrogen fugacity (fH₂) and initial composition. One example of such a test is given for an early, sudden outgassing of the Earth, in which CO₂, H₂O, and N₂ are transported from the mantle to the atmosphere by hydrothermal solutions. Activities of metastable aqueous organic species which form as a consequence of this process are evaluated at conditions appropriate for seafloor hydrothermal systems, and are found to maximize at about 200 °C and between the oxidation states set by two mineral assemblages common in the oceanic crust.     

New insight into the colonization processes of common voles: inferences from molecular and fossil evidence

Elucidating the colonization processes associated with Quaternary climatic cycles is important in order to understand the distribution of biodiversity and the evolutionary potential of temperate plant and animal species. In Europe, general evolutionary scenarios have been defined from genetic evidence. Recently, these scenarios have been challenged with genetic as well as fossil data. The origins of the modern distributions of most temperate plant and animal species could predate the Last Glacial Maximum. The glacial survival of such populations may have occurred in either southern (Mediterranean regions) and/or northern (Carpathians) refugia. Here, a phylogeographic analysis of a widespread European small mammal (Microtus arvalis) is conducted with a multidisciplinary approach. Genetic, fossil and ecological traits are used to assess the evolutionary history of this vole. Regardless of whether the European distribution of the five previously identified evolutionary lineages is corroborated, this combined analysis brings to light several colonization processes of M. arvalis. The species' dispersal was relatively gradual with glacial survival in small favourable habitats in Western Europe (from Germany to Spain) while in the rest of Europe, because of periglacial conditions, dispersal was less regular with bottleneck events followed by postglacial expansions. Our study demonstrates that the evolutionary history of European temperate small mammals is indeed much more complex than previously suggested. Species can experience heterogeneous evolutionary histories over their geographic range. Multidisciplinary approaches should therefore be preferentially chosen in prospective studies, the better to understand the impact of climatic change on past and present biodiversity.     

New insight into the role of miRNAs in leukemia

Recent studies have shown that microRNAs(miRNAs) play an important role in cell differentiation, growth, and death, including the functional study of miRNAs in tumorigenesis. To date, miRNA expression profiles in many types of cancers have been identified and miRNA expression signatures associated with types and cytogenetics of leukemia have also been reported. Increasing evidence has shown that miRNAs could function as either tumor suppressors or oncogenes in cancers such as leukemia, while other miRNAs might be benefitcial for diagnosis and prognosis, predicted to be newly developed biomarkers. In this review, we summarize the recent progress about miRNAs in leukemia and present a miRNA-mediated network involved in differentiation, proliferation and apoptosis predicted to be the roles of miRNAs in the pathogenesis of leukemia. Supported by National Natural Science Foundation of China (Grant No. 30672254 and 30872784), National High-Tech Research and Development Program of China (Grant No. 2008AA02Z106).     

Metabolism of organic compounds in anaerobic,hydrothermal sulphate-reducing marine sediments

Previous studies of hot (>80 degrees C) microbial ecosystems have primarily relied on the study of pure cultures or analysis of 16S rDNA sequences. In order to gain more information on anaerobic metabolism by natural communities in hot environments, sediments were collected from a shallow marine hydrothermal vent system in Baia di Levante, Vulcano, Italy and incubated under strict anaerobic conditions at 90 degrees C. Sulphate reduction was the predominant terminal electron-accepting process in the sediments. The addition of molybdate inhibited sulphate reduction in the sediments and resulted in a linear accumulation of acetate and hydrogen over time. [U-14C]- acetate was completely oxidized to 14CO2, and the addition of molybdate inhibited 14CO2 production by 60%. [U-14C]-glucose was oxidized to 14CO2, and this was inhibited when molybdate was added. When the pool sizes of short-chain fatty acids were artificially increased, radiolabel from [U-14C]-glucose accumulated in the acetate pool. L-[U-14C]-glutamate, [ring-14C]-benzoate and [U-14C]-palmitate were also anaerobically oxidized to 14CO2 in the sediments, but molybdate had little effect on the oxidation of these compounds. These results demonstrate that natural microbial communities living in a hot, microbial ecosystem can oxidize acetate and a range of other organic electron donors under sulphate-reducing conditions and suggest that acetate is an important extracellular intermediate in the anaerobic degradation of organic matter in hot microbial ecosystems.     

New insight into the treatment of aortic stenosis

Aortic valve stenosis (AS) is the most frequent heart disease after coronary artery disease and arterial hypertension and it is associated with a high incidence of adverse outcomes. Historically, calcific AS has been considered as "degenerative" because it was thought to be the result from aging and "wear and tear" of the aortic valve. However, this perception has changed over the years with the publication of several studies showing that the calcific AS shares many histological similarities with atherosclerosis, thus suggesting that this disease could eventually be modified by lifestyle or pharmacological therapies. Furthermore, recent data support the notion that AS is not an isolated disease uniquely limited to the valve. Indeed, AS is frequently associated with abnormalities of the systemic arterial system, and in particular with reduced arterial compliance, which may have important consequences on the pathophysiology and clinical outcome of this disease. Hence, the assessment of AS severity as well as its therapeutic management should be conducted with the use of a comprehensive evaluation that includes not only the aortic valve but also the systemic arterial system and the left ventricle, since these 3 entities are tightly intricated on both the pathophysiological and hemodynamic standpoints.     

植物源挥发性有机物对氮沉降响应研究展望

植物排放的挥发性有机物(Biogenic volatile organic compounds, BVOCs),属于植物次生代谢物质,是植物重要的防御物质,亦是全球碳(C)素循环的一个重要组成部分。它们具有很高的化学活性,参与对流层大气化学过程,并对全球变化和碳氮(N)循环等具有潜在的影响。尽管N沉降全球化已严重干扰了生态系统的碳氮循环,并且已威胁到生态系统的健康和安全。然而N沉降对BVOCs影响的研究报道十分缺乏。综述了BVOCs影响因素的基础上,重点论述了N素对BVOCs的影响,提出了N沉降对植物BVOCs影响的趋势模型:在N素不足的系统中,N沉降的增加补充了系统所需的N素,有利于植物的生长,大量BVOCs的排放会受到抑制;在N素丰富或过量的系统中,N沉降导致系统N素过饱和或富营养化,不利于植物的生长,刺激BVOCs的排放增加。此外,还探讨了研究N沉降对BVOCs影响的可行性方法,强调开展我国N沉降对BVOCs的影响研究的重要性和紧迫性。为我国开展N沉降对BVOCs的影响研究以及加深了解生态系统CN循环及其藕合提供参考。     

New insight into the flavonoid composition of Chenopodium botrys

Due to their beneficial medicinal effects, in recent years there has been an increasing interest in the research of flavonoids in plant sources.In the conducted research the flavonoid composition of Chenopodium botrys was defined by applying an approach which included different extraction procedures and methods of detection. Primary extraction of polyphenols with two different solvents, HPLC-PDA fingerprint profiling and an Orbitrap UHPLC-MS/MS detection were used. The fingerprint profile of polyphenols showed that the major constituents were the methoxylated flavones nepetin, hispidulin and jaceosidin, while the quercetin glycosides represented a minor part. In order to elucidate their structure, the fragmentation of the compounds was examined by means of ESI-MS/MS analysis. A novel explanation of the fragmentation pathways of the methoxylated flavones was introduced. Nepetin, nobiletin, eupatilin, rutin and quercetin-3-O-galactoside were identified in the polyphenol complex of C. botrys for the first time.     

New insight into the structure and function of the alternative oxidase

The alternative oxidase is a ubiquinol oxidase found in plant mitochondria, as well as in the mitochondria of some fungi and protists. It catalyzes a cyanide-resistant reduction of oxygen to water without translocation of protons across the inner mitochondrial membrane, and thus functions as a non-energy-conserving member of the respiratory electron transfer chain. The active site of the alternative oxidase has been modelled as a diiron center within a four-helix bundle by Siedow et al. (FEBS Lett. 362 (1995) 10-14) and more recently by Andersson and Nordlund (FEBS Lett. 449 (1999) 17-22). The cloning of the Arabidopsis thaliana IMMUTANS (Im) gene, which encodes a plastid enzyme distantly related to the mitochondrial alternative oxidases (Wu et al. Plant Cell 11 (1999) 43-55; Carol et al. Plant Cell 11 (1999) 57-68), has now narrowed the range of possible ligands to the diiron center of the alternative oxidase. The Im protein sequence suggests a minor modification to the recent model of the active site of the alternative oxidase. This change moves an invariant tyrosine into a conserved hydrophobic pocket in the vicinity of the active site, in a position analogous to the long-lived tyrosine radical at the diiron center of ribonucleotide reductase, and similar to the tyrosines near the diiron center of bacterioferritin and rubrerythrin. The Im sequence and modified structural model yield a compelling picture of the alternative oxidase as a diiron carboxylate protein. The current status of the relationship of structure to function in the alternative oxidase is reviewed.     

New insight into the molecular mechanisms of two-partner secretion

Two-partner secretion (TPS) systems, which export large proteins to the surface and/or extracellular milieu of Gram-negative bacteria, are members of a large superfamily of protein translocation systems that are widely distributed in animals, plants and fungi, in addition to nearly all groups of Gram-negative bacteria. Recent intense research on TPS systems has provided new insight into the structure and topology of the outer membrane translocator proteins and the large exoproteins that they secrete, the interactions between them, and mechanisms for retention of some of the secreted proteins on the bacterial surface. Evidence for secretion-dependent folding of mature exoproteins has also been obtained. Together, these findings provide a deeper understanding of the molecular mechanisms underlying these simple but elegant secretion systems.     

New insight into the diagnosis of fastidious bacterial endocarditis

Sterile blood cultures are noted in one third of patients with infectious endocarditis. Although in half of cases this is due to previous antibiotic therapy, in the other half, the aetiology of culture-negative endocarditis is intracellular bacteria such as Coxiella burnetii or fastidious growing bacteria. Although it was previously considered that the prevalence of such organisms was identical throughout the world, recent investigations on Bartonella endocarditis clearly showed that the aetiology of culture-negative endocarditis is likely to be strongly related to epidemiology of the agent in each country. During the past decade the use of molecular techniques such as PCR with subsequent sequencing to detect or to identify bacteria in valves from patients with infectious endocarditis have considerably improved the aetiological diagnosis. This is especially true in the case of culture-negative endocarditis following earlier antibiotic therapy. However, the fact that DNA remnants of past endocarditis can be detected some time after the acute episode, when the patient has been cured, suggests that the predictive value of these techniques along with the traditional histology and culture need to be evaluated closely.     

New insight into the molecular pathways of metallothionein-mediated neuroprotection and regeneration

There is a large body of evidence demonstrating that metallothioneins (MTs) expressed in astrocytes following CNS injury, exhibit both neuroprotective and neuroregenerative properties and are critical for recovery outcomes. As these proteins lack signal peptides, and have well characterized free radical scavenging and heavy metal binding properties, the neuroprotective functions of MTs have been attributed to these intracellular roles. However, there is an increasing realization that the neuroprotective functions of MTs may also involve an extracellular component. In this issue of Journal of Neurochemistry , Ambjørn et al. reveal considerable insight into this novel function of MTs. In this review, we examine the seminal work of Ambjørn et al. in the context of our current understanding of the role of MT in astrocyte-neuron interactions in the injured brain, and also discuss the significant therapeutic potential of their work.     

New insight into the role of extracellular vesicles in kidney disease

Extracellular vesicles (EVs) are released to maintain cellular homeostasis as well as to mediate cell communication by spreading protective or injury signals to neighbour or remote cells. In kidney, increasing evidence support that EVs are signalling vesicles for different segments of tubules, intra‐glomerular, glomerular‐tubule and tubule‐interstitial communication. EVs released by kidney resident and infiltrating cells can be isolated from urine and were found to be promising biomarkers for kidney disease, reflecting deterioration of renal function and histological change. We have here summarized the recent progress about the functional role of EVs in kidney disease as well as challenges and future directions involved.     

New insight into the catalytic properties of bile salt hydrolase

Bile salt hydrolase (BSH), the enzyme deconjugating bile potentially plays an important role in reduction of blood cholesterol level. BSH enzymes from various sources differ in characteristics, substrates preference and specific catalytic activity. In this study, two BSH enzymes (BSH1 and BSH2) from Lactobacillus salivarius were heterologously expressed and purified. Both of them were characterized as homotetramer according to their molecular weight from size exclusion chromatograph. BSH1 showed a broad pH optimum over the range from 5.5 to 7.0, while a narrower range of pH optimum from 5.5 to 6.0 for BSH2 was detected. The enzymatic kinetics of the purified BSH1 and BSH2 have demonstrated BSH enzymes from bacteria were allosteric enzymes, and have also revealed their striking differences in positive cooperativity, catalytic efficiency and substrate preference for the first time. In contrast to the enzymatic reactions of BSH in the absence of dithiothreitol, the kinetics curves of BSH1 and BSH2 were similar to hyperbolic forms of Michaelis–Menten kinetics in the presence of dithiothreitol.