Application of a Mass Spectrometric Approach to Detect the Presence of Fatty Acid Biosynthetic Phosphopeptides

The details of plant lipid metabolism are relatively well known but the regulation of fatty acid production at the protein level is still not understood. Hence this study explores the importance of phosphorylation as a mechanism to control the activity of fatty acid biosynthetic enzymes using low and high oleic acid mesocarps of oil palm fruit (Elaeis guineensis variety of Tenera). Adaptation of neutral loss-triggered tandem mass spectrometry and selected reaction monitoring to detect the neutral loss of phosphoric acid successfully found several phosphoamino acid-containing peptides. These peptides corresponded to the peptides from acetyl-CoA carboxylase and 3-enoyl-acyl carrier protein reductase as identified by their precursor ion masses. These findings suggest that these enzymes were phosphorylated at 20th week after anthesis. Phosphorylation could have reduce their activities towards the end of fatty acid biosynthesis at ripening stage. Implication of phosphorylation in the regulation of fatty acid biosynthesis at protein level has never been reported.     

Integration of New Endogenous Mouse Mammary Tumor Virus Proviral DNA at Common Sites in the DNA of Mammary Tumors of C3Hf Mice and Hypomethylation of the Endogenous Mouse Mammary Tumor Virus Proviral DNA in C3Hf Mammary Tumors and Spleens

To understand the molecular mechanisms by which the endogenous murine mammary tumor virus (MuMTV) proviruses are expressed and produce late-occurring mammary tumors in C3Hf mice, we analyzed, by the use of restriction enzymes and the Southern transfer procedure, genomic DNA from normal organs of mammary tumor-bearing and tumor-free mice and from 12 late-occurring C3Hf mammary tumors. We found, by using the restriction enzymes EcoRI and HindIII, that in addition to the preexisting endogenous MuMTV proviruses, new MuMTV-specific proviral DNA was integrated into new sites in the host genome in all 12 of the tumors that we examined. PstI digests of C3Hf tumor DNA revealed that the new proviral DNA found in C3Hf tumors was of endogenous origin. Moreover, the respective sizes of at least one of the new DNA fragments generated by EcoRI or HindIII digestion were the same in at least 50% of the C3Hf tumors analyzed, suggesting that the integration site of this new proviral DNA could be at the same location in the host genome of these tumors. Our results may imply that mammary tumorigenesis in C3Hf mice results from activation of cellular oncogenes by an MuMTV proviral DNA promoter. Specific hypomethylation of MuMTV proviral DNA was detected in the mammary tumors and spleens of C3Hf tumor-bearing mice. Our results indicated that most, if not all, of the hypomethylated MuMTV proviral DNA sequences were derived from the endogenous MuMTV provirus located at the MTV-1 locus, a locus responsible for the production of MuMTV antigens and increased incidence of mammary carcinoma in C3Hf mice. In spleens of non-tumor-bearing mice of ages 3, 6, 9, and 12 months, there was progressive hypomethylation of proviral DNA with increasing age, suggesting a possible correlation between demethylation of MuMTV proviral DNA in the spleens of C3Hf mice and the expression of endogenous MuMTV.     

Helical Nucleocapsid Structure of the Oncogenic Ribonucleic Acid Viruses (Oncornaviruses)

Negative staining of virions and isolated nucleoids from avian myeloblastosis virus, murine leukemia virus, murine mammary tumor virus, and feline leukemia virus reveals common internal structures. The majority of virions that are penetrated by phosphotungstate show spherical nucleoids with no apparent symmetry. In a small percentage of virions, two distinctive structures are found: (i) single strands (3 to 5 nm in diameter) which are presumed to be the nucleoprotein and are found randomly oriented throughout the viral interior and (ii) helical structures (7 to 9 nm in diameter) which contain these nucleoprotein strands and are observed at the periphery of the nucleoid. The finding of helical nucleocapsid segments at the periphery of the nucleoid, as well as the hollow spherical structure observed in thin section of budding virions, has led to the hypothesis that the nucleocapsid of the freshly budded oncornavirus is supercoiled as a hollow sphere. This symmetry, however, is considered transient, as the internal structure of the extracellular virus undergoes a conformational rearrangement; thus, due to structural instability, the nucleocapsid uncoils and the nucleoprotein strands fill the interior of the virion. The extracellular virion is therefore considered degenerate in respect to symmetry, explaining the difficulty in detecting a helical nucleocapsid.     

Pesticidal and pest repellency activities of rhizomes of Drynaria quercifolia (J. Smith) against Tribolium castaneum (Herbst)

Background

Tribolium castaneum (Herbst) is a harmful pest of stored grain and flour-based products in tropical and subtropical region. In the present study, rhizome of Drynaria quercifolia (J. Smith) was evaluated for pesticidal and pest repellency activities against T. castaneum, using surface film method and filter paper disc method, respectively. In addition, activity of the isolated compound 3,4-dihydroxybenzoic acid was evaluated against the pest.

Results

Chloroform soluble fraction of ethanol extract of rhizome of D. quercifolia showed significant pesticidal activity at doses 0.88 to 1.77 mg/cm² and significant pest repellency activity at doses 0.94 to 0.23 mg/cm². No pesticidal and pest repellency activity was found for petroleum ether, ethyl acetate and methanol soluble fractions of ethanol extract as well as for 3,4-dihydroxybenzoic acid.

Conclusion

Considering our findings it can be concluded that chloroform soluble fraction of rhizome of D. quercifolia is useful in controlling T. castaneum of stored grain and flour-based products.

Electronic supplementary material

The online version of this article (doi:10.1186/0717-6287-47-51) contains supplementary material, which is available to authorized users.     

In-Vitro Activity of Doxycycline and β-Lactam Combinations Against Different Strains of <Emphasis Type="Italic">Burkholderia pseudomallei</Emphasis>

Although doxycycline is active against Burkholderia pseudomallei and has been used in the eradication stage of melioidosis therapy, it is not regularly used during the initial intensive phase. In order to assess its potential use in intensive phase therapy, we investigated in vitro pharmacodynamic activity of doxycycline and β-lactams alone and in combination against four Malaysian strains of B. pseudomallei. Using a checkerboard assay, the combinations of doxycycline and imipenem, doxycycline and ceftazidime, and doxycycline and amoxicillin–clavulanate tested against four strains showed indifferent effects with summation fractional inhibitory concentration values ranging from 0.62 to 2.12. Time-kill experiments also indicated that the combinations of doxycycline/β-lactam antibiotics against four tested strains did not fulfil synergy criteria, in which all combinations showed indifferent effects with ? 1.36 to 1.26-log CFU/mL compared to the most active monotherapy regimen in each combination. No re-growth of bacteria was detected after the early killing in doxycycline/β-lactam combination regimens compared to β-lactam monotherapy regimens, in which 9 out of 10 were associated with re-growth of bacteria. As no synergistic activity was observed, this in vitro study showed that doxycycline offers no additional benefit to be used in combination with β-lactams in the intensive phase of therapy.     

Desmids of Iraq

Forty species and varieties of desmids belonging to the genera Closterium (7), Pleurotaenium (1), Euastrum (3), Cosmarium (28) and Staurastrum (1) have been described from southern Iraq including two new varieties under Cosmarium (i.e. C. cyclicum Lund, var. mesopotamianum var. nov., and C. tyrolicum (Nordst.) Krieger & Gerloff var. minor var. nov.). Most of the taxa are new records for Iraq.     

Antidepressant-like effect of mitragynine isolated from Mitragyna speciosa Korth in mice model of depression

Mitragyna speciosa Korth. leaves have been used for decades as a traditional medicine to treat diarrhea, diabetes and to improve blood circulation by natives of Malaysia, Thailand and other regions of Southeast Asia. Mitragynine is the major active alkaloid in the plant. To date, the role of mitragynine in psychological disorders such as depression is not scientifically evaluated. Hence, the present investigation evaluates the antidepressant effect of mitragynine in the mouse forced swim test (FST) and tail suspension test (TST), two models predictive of antidepressant activity and the effect of mitragynine towards neuroendocrine system of hypothalamic-pituitary-adrenal (HPA) axis by measuring the corticosterone concentration of mice exposed to FST and TST. An open-field test (OFT) was used to detect any association of immobility in the FST and TST with changes in motor activity of mice treated with mitragynine. In the present study, mitragynine at dose of 10 mg/kg and 30 mg/kg i.p. injected significantly reduced the immobility time of mice in both FST and TST without any significant effect on locomotor activity in OFT. Moreover, mitragynine significantly reduced the released of corticosterone in mice exposed to FST and TST at dose of 10 mg/kg and 30 mg/kg. Overall, the present study clearly demonstrated that mitragynine exerts an antidepressant effect in animal behavioral model of depression (FST and TST) and the effect appears to be mediated by an interaction with neuroendocrine HPA axis systems.     

Comparative Study on Biological Activities and Chemical Profiling of Mushroom (Pleurotus pulmonarius (Fr.) Quel.) Cultured on Lignocellulosic Agro Wastes

The relevance of the lignocellulosic substrate in the cultivation of mushrooms has lent support to the exploration of several lignocellulosic agro wastes. This study was, thus, aimed at the evaluation of durian peel as an alternative substrate for more sustainable mushroom cultivation and climate change mitigation. The secondary metabolites and biological activities of both aqueous and organic mushroom (Pleurotus pulmonarius (Fr.) Quel.) extract cultured on durian peel and rubberwood sawdust substrate were compared using GCMS, LCMS as well as various biological assays (cytotoxicity, antimicrobial and antioxidant activities). Mushroom extracts from durian peel substrates possess remarkable biological activities. The results showed that the aqueous extracts had poor antimicrobial activities. The organic extracts were more active against cancer cells than the aqueous extracts, while the aqueous extracts were more potent as antioxidants than the organic extracts. Overall, the mushroom extract from the durian substrate was the most effective except against A549 and SW948, while the aqueous extract from the durian substrate was the most effective against the A549 cancer cell lines with 29.53±2.39 % inhibition. On the other hand, the organic mushroom extract from the sawdust substrate was the most effective against SW948 with 60.24±2.45 % inhibition. Further studies, however, are needed to elucidate the molecular mechanism of action of P. pulmonarius extracts against cancer cell proliferation and the effect of the substrates on the nutritional composition, secondary metabolites, and other biological activities of P. pulmonarius extracts.     

Modeling protein-protein,protein-peptide,and protein-oligosaccharide complexes: CAPRI 7th edition

We present the seventh report on the performance of methods for predicting the atomic resolution structures of protein complexes offered as targets to the community-wide initiative on the Critical Assessment of Predicted Interactions. Performance was evaluated on the basis of 36 114 models of protein complexes submitted by 57 groups—including 13 automatic servers—in prediction rounds held during the years 2016 to 2019 for eight protein-protein, three protein-peptide, and five protein-oligosaccharide targets with different length ligands. Six of the protein-protein targets represented challenging hetero-complexes, due to factors such as availability of distantly related templates for the individual subunits, or for the full complex, inter-domain flexibility, conformational adjustments at the binding region, or the multi-component nature of the complex. The main challenge for the protein-peptide and protein-oligosaccharide complexes was to accurately model the ligand conformation and its interactions at the interface. Encouragingly, models of acceptable quality, or better, were obtained for a total of six protein-protein complexes, which included four of the challenging hetero-complexes and a homo-decamer. But fewer of these targets were predicted with medium or higher accuracy. High accuracy models were obtained for two of the three protein-peptide targets, and for one of the protein-oligosaccharide targets. The remaining protein-sugar targets were predicted with medium accuracy. Our analysis indicates that progress in predicting increasingly challenging and diverse types of targets is due to closer integration of template-based modeling techniques with docking, scoring, and model refinement procedures, and to significant incremental improvements in the underlying methodologies.