Metabolomics and lipid profile analysis of Coccomyxa melkonianii SCCA 048

Extremophiles - With an unsupervised GC–MS metabolomics approach, polar metabolite changes of the microalgae Coccomyxa melkonianii SCCA 048 grown under standard conditions for seven weeks...     

Behavior of the extremophile green alga Coccomyxa melkonianii SCCA 048 in terms of lipids production and morphology at different pH values

Extremophiles - The extremophile green alga Coccomyxa melkonianii SCCA 048 was investigated to evaluate its ability to grow in culture media with different pH. Specifically, Coccomyxa melkonianii...     

An O Antigen Capsule Modulates Bacterial Pathogenesis in Shigella sonnei

Shigella is the leading cause for dysentery worldwide. Together with several virulence factors employed for invasion, the presence and length of the O antigen (OAg) of the lipopolysaccharide (LPS) plays a key role in pathogenesis. S. flexneri 2a has a bimodal OAg chain length distribution regulated in a growth-dependent manner, whereas S. sonnei LPS comprises a monomodal OAg. Here we reveal that S. sonnei, but not S. flexneri 2a, possesses a high molecular weight, immunogenic group 4 capsule, characterized by structural similarity to LPS OAg. We found that a galU mutant of S. sonnei, that is unable to produce a complete LPS with OAg attached, can still assemble OAg material on the cell surface, but a galU mutant of S. flexneri 2a cannot. High molecular weight material not linked to the LPS was purified from S. sonnei and confirmed by NMR to contain the specific sugars of the S. sonnei OAg. Deletion of genes homologous to the group 4 capsule synthesis cluster, previously described in Escherichia coli, abolished the generation of the high molecular weight OAg material. This OAg capsule strongly affects the virulence of S. sonnei. Uncapsulated knockout bacteria were highly invasive in vitro and strongly inflammatory in the rabbit intestine. But, the lack of capsule reduced the ability of S. sonnei to resist complement-mediated killing and to spread from the gut to peripheral organs. In contrast, overexpression of the capsule decreased invasiveness in vitro and inflammation in vivo compared to the wild type. In conclusion, the data indicate that in S. sonnei expression of the capsule modulates bacterial pathogenesis resulting in balanced capabilities to invade and persist in the host environment.     

Botanical nematicides in the mediterranean basin

Achieving food sufficiency in a sustainable manner is a major challenge for farmers, agro-industries, researchers and governments. Amongst agricultural pests supressing crops, root-knot nematodes (Meloidogyne spp.) represent possibly the world’s most damaging one, the control of which has been mainly based on chemical nematicides. In the recent years the environmental, food safety and animal welfare issues pose the need for alternative nematode control measures. Screening naturally occurring compounds in plants, involved in the complex chemical-mediated interactions between a plant and other organisms in its environment, can provide with innovative nematode control measures that can be safely used in integrated pest management programs. The Mediterranean Basin is an area where various soils and climatic conditions allow a vast plant biodiversity providing with chemical botanicals of significant nematicidal potency. This is a review on the Mediterranean botanicals that can control Meloidogyne spp.     

Inhibition of S-phase progression triggered by UVA-induced ROS does not require a functional DNA damage checkpoint response in mammalian cells

Ultraviolet A (UVA) radiation represents more than 90% of the UV spectrum reaching Earth's surface. Exposure to UV light, especially the UVA part, induces the formation of photoexcited states of cellular photosensitizers with subsequent generation of reactive oxygen species (ROS) leading to damages to membrane lipids, proteins and nucleic acids. Although UVA, unlike UVC and UVB, is poorly absorbed by DNA, it inhibits cell cycle progression, especially during S-phase. In the present study, we examined the role of the DNA damage checkpoint response in UVA-induced inhibition of DNA replication. We provide evidence that UVA delays S-phase in a dose dependent manner and that UVA-irradiated S-phase cells accumulate in G2/M. We show that upon UVA irradiation ATM-, ATR- and p38-dependent signalling pathways are activated, and that Chk1 phosphorylation is ATR/Hus1 dependent while Chk2 phosphorylation is ATM dependent. To assess for a role of these pathways in UVA-induced inhibition of DNA replication, we investigated (i) cell cycle progression of BrdU labelled S-phase cells by flow cytometry and (ii) incorporation of [methyl-(3)H]thymidine, as a marker of DNA replication, in ATM, ATR and p38 proficient and deficient cells. We demonstrate that none of these pathways is required to delay DNA replication in response to UVA, thus ruling out a role of the canonical S-phase checkpoint response in this process. On the contrary, scavenging of UVA-induced reactive oxygen species (ROS) by the antioxidant N-acetyl-l-cystein or depletion of vitamins during UVA exposure significantly restores DNA synthesis. We propose that inhibition of DNA replication is due to impaired replication fork progression, rather as a consequence of UVA-induced oxidative damage to protein than to DNA.     

Effect of 1,2-benzisoxazole-3-acetic acid on adventitious shoot regeneration and in vitro rooting in apple

 The effect of 1,2-benzisoxazole-3-acetic acid (BOA), compared to 1-naphthaleneacetic acid (NAA), on adventitious shoot formation in leaf portions and compared to indolebutyric acid (IBA), on in vitro rooting in the apple (Malus domestica Borkh) cultivars McIntosh and Gala, and one rootstock, Jork 9, was investigated. BOA at 43.0 μm or 2.7 μm at NAA in combination with 17.8 μm benzyladenine (BA), induced the highest number of explants to produce adventitious shoots in Jork 9. In Gala, the combination of 21.5 μm BOA with 1.0 μm thidiazuron (TDZ) or with 22.0 μm BA induced the highest regeneration percentages, 58 and 54%, respectively, giving more satisfactory results than NAA (where only 42% of leaf explants exhibited shoot formation). In McIntosh, the highest percentage of regeneration was obtained with 1.3 μm NAA and 22.0 μm BA, while 51% was the highest response obtained with the BOA treatment. The combination of BOA with TDZ completely inhibited regeneration activity in leaf portions of this cultivar. The shoots of all the genotypes obtained with the most morphogenetic NAA or BOA treatments were excised, multiplied and successfully rooted and hardened. The results demonstrate that the synthetic auxin BOA is active in inducing shoot regeneration from leaf explants of apple and that the activity of BOA in plant regeneration is genotype dependent. When BOA was used to induce rooting in apple microcuttings, lower rooting percentages were obtained than with IBA, showing that the effect of BOA in inducing root formation is very low and that it cannot be used routinely to replace IBA in the in vitro rooting of microcuttings. Received: 18 June 1998 / Revision received: 4 January 1999 / Accepted: 29 January 1999     

Italian cohort of patients affected by inflammatory bowel disease is characterised by variation in glycerophospholipid,free fatty acids and amino acid levels

Background

Inflammatory bowel disease is a group of pathologies characterised by chronic inflammation of the intestine and an unclear aetiology. Its main manifestations are Crohn’s disease and ulcerative colitis. Currently, biopsies are the most used diagnostic tests for these diseases and metabolomics could represent a less invasive approach to identify biomarkers of disease presence and progression.

Objectives

The lipid and the polar metabolite profile of plasma samples of patients affected by inflammatory bowel disease have been compared with healthy individuals with the aim to find their metabolomic differences. Also, a selected sub-set of samples was analysed following solid phase extraction to further characterise differences between pathological samples.

Methods

A total of 200 plasma samples were analysed using drift tube ion mobility coupled with time of flight mass spectrometry and liquid chromatography for the lipid metabolite profile analysis, while liquid chromatography coupled with triple quadrupole mass spectrometry was used for the polar metabolite profile analysis.

Results

Variations in the lipid profile between inflammatory bowel disease and healthy individuals were highlighted. Phosphatidylcholines, lyso-phosphatidylcholines and fatty acids were significantly changed among pathological samples suggesting changes in phospholipase A₂ and arachidonic acid metabolic pathways. Variations in the levels of cholesteryl esters and glycerophospholipids were also found. Furthermore, a decrease in amino acids levels suggests mucosal damage in inflammatory bowel disease.

Conclusions

Given good statistical results and predictive power of the model produced in our study, metabolomics can be considered as a valid tool to investigate inflammatory bowel disease.