Communities of culturable yeasts and yeast-like fungi in oligotrophic hypersaline coastal waters of the Arabian Gulf surrounding Qatar

This report is the first investigation of yeast biodiversity from the oligotrophic hypersaline coastal waters of the Arabian Gulf surrounding Qatar. Yeasts and yeast-like fungi, were cultured from seawater sampled at 13 coastal areas surrounding Qatar over a period of 2 years (December 2013–September 2015). Eight hundred and forty-two isolates belonging to 82 species representing two phyla viz., Ascomycota (23 genera) and Basidiomycota (16 genera) were identified by molecular sequencing. The results indicated that the coastal waters of the Qatari oligotrophic marine environment harbor a diverse pool of yeast species, most of which have been reported from terrestrial, clinical and aquatic sources in various parts of the world. Five species, i.e., Candida albicans, C. parapsilosis, C. tropicalis, Pichia kudriavzevii and Meyerozyma guilliermondii (n?=?252/842; 30% isolates) are known as major opportunistic human pathogens. Fifteen species belonging to nine genera (n?=?498/842; 59%) and 12 species belonging to seven genera (n?=?459/842; 55%) are hydrocarbon degrading yeast and pollution indicator yeast species, respectively. Ascomycetous yeasts were predominant (66.38%; 559/842) as compared to their basidiomycetous counterparts (33.6%; 283/842). The most isolated yeast genera were Candida (28%; 236/842) (e.g., C. aaseri, C. boidinii, C. glabrata, C. intermedia, C. oleophila, C. orthopsilosis, C. palmioleophila, C. parapsilosis, C. pseudointermedia, C. rugopelliculosa, C. sake, C. tropicalis and C. zeylanoides), Rhodotorula (12.7%; 107/842), Naganishia (8.4%; 71/842), Aureobasidium (7.4%; 62/842), Pichia (7.3%; 62/842), and Debaryomyces (6.4%; 54/842). A total of eleven yeast species ( n = 38) isolated in this study are reported for the first time from the marine environment. Chemical testing demonstrated that seven out of the 13 sites had levels of total petroleum hydrocarbons (TPH) ranging from 200 to 900 µg/L, whereas 6 sites showed higher TPH levels (>?1000–21000 µg/L). The results suggest that the yeast community structure and density are impacted by various physico-chemical factors, namely total organic carbon, dissolved organic carbon and sulphur.

     

Sulfation, the up-and-coming post-translational modification: its role and mechanism in protein-protein interaction

Tyrosine sulfation is a post-translational modification entailing covalent attachment of sulfate to tyrosine residues. It takes place in the trans-Golgi, is necessary for the bioactivity of some proteins, and improves their ability to interact with other proteins. In the present work, we show that a protein containing a sulfated tyrosine with a delocalized negative charge forms a salt bridge with another protein if it has two or more adjacent arginine residues containing positive delocalized charges. These noncovalent complexes are so stable that, when submitted to collision induced dissociation, the peptides forming the complex dissociate. Just one covalent bond fragments, the covalent bond between the tyrosine oxygen and the SO3 sulfur, and is represented by the appearance of a new peak (basic peptide + SO3), suggesting that in some instances covalent bonds will break down before the noncovalent bonds between the arginine guanidinium and SO3 dissociate. The data implies that the dissociation pathway is preferred; however, fragmentation between tyrosine and the sulfate residue is a major pathway.     

HPTLC and GC/MS Study of Amaryllidaceae Alkaloids of Two Narcissus Species

In this article, we report on the alkaloid profile and dynamic of alkaloid content and diversity in two Narcissus plants at different stages of development. The alkaloid profile of the two Narcissus species was investigated by GC/MS and HPTLC. Fifty eight Amaryllidaceae alkaloids were detected, and 25 of them were identified in the different organs of N. tazetta and N. papyraceus. The alkaloid 3‐O‐methyl‐9‐O‐demethylmaritidine is tentatively identified here for the first time from the Amaryllidaceae family, and four alkaloids (tazettamide, sternbergine, 1‐O‐acetyllycorine, 2,11‐didehydro‐2‐dehydroxylycorine) are tentatively identified for the first time in the genus Narcissus. The different organs of the two species analyzed showed remarkable differences in their alkaloid pattern, type of biosynthesis, main alkaloid and number of alkaloids. Lycorine‐type alkaloids dominated the alkaloid, metabolism in N. papyraceus, while alkaloids of narciclasine‐, galanthamine‐ and homolycorine‐types were found only in the species N. tazetta L.     

NOX5 in human spermatozoa: expression, function, and regulation

Physiological and pathological processes in spermatozoa involve the production of reactive oxygen species (ROS), but the identity of the ROS-producing enzyme system(s) remains a matter of speculation. We provide the first evidence that NOX5 NADPH oxidase is expressed and functions in human spermatozoa. Immunofluorescence microscopy detected NOX5 protein in both the flagella/neck region and the acrosome. Functionally, spermatozoa exposed to calcium ionophore, phorbol ester, or H(2)O(2) exhibited superoxide anion production, which was blocked by addition of superoxide dismutase, a Ca(2+) chelator, or inhibitors of either flavoprotein oxidases (diphenylene iododonium) or NOX enzymes (GKT136901). Consistent with our previous overexpression studies, we found that H(2)O(2)-induced superoxide production by primary sperm cells was mediated by the non-receptor tyrosine kinase c-Abl. Moreover, the H(V)1 proton channel, which was recently implicated in spermatozoa motility, was required for optimal superoxide production by spermatozoa. Immunoprecipitation experiments suggested an interaction among NOX5, c-Abl, and H(V)1. H(2)O(2) treatment increased the proportion of motile sperm in a NOX5-dependent manner. Statistical analyses showed a pH-dependent correlation between superoxide production and enhanced sperm motility. Collectively, our findings show that NOX5 is a major source of ROS in human spermatozoa and indicate a role for NOX5-dependent ROS generation in human spermatozoa motility.     

Leishmania major: Reactive oxygen species and interferon gamma induction by soluble lipophosphoglycan of stationary phase promastigotes

Protozoan parasites of the genus Leishmania cause a number of important human diseases. One of the key determinants of parasite infectivity and survival is membrane glycoconjugate lipophosphoglycan (mLPG). In addition, it has been shown that mLPG could be used as a transmission blocking vaccine. Since culture supernatant of parasite promastigotes is a good source of LPG, we attempted to compare the immunological properties of culture supernatant and membrane LPG prepared from stationary phase promastigotes of Leishmania major. The purity of supernatant LPG (sLPG) and membrane LPG (mLPG) was determined by thin layer chromatography. The effect of sLPG and mLPG on the production of reactive oxygen species (ROS) was studied using PBMCs isolated from healthy individuals. In addition, induction of IL-12, IFN-gamma and IL-10 secretion in the presence of sLPG and mLPG was investigated. Reactive oxygen species in addition to IL-10 and IL-12 were induced by both sLPG and mLPG. However, IFN-gamma production was promoted only in response to sLPG suggesting its ability to promote Th1 response and implication in vaccine design.     

Biological activities of the essential oils and methanol extract of tow cultivated mint species (<Emphasis Type="Italic">Mentha longifolia</Emphasis> and <Emphasis Type="Italic">Mentha pulegium</Emphasis>) used in the Tunisian folkloric medicine

The composition of the essential oils and methanolic extracts of two cultivated mint species (M. longifolia and M. pulegium), as well as the in vitro antimicrobial and antioxidant activities of the essential oil and methanol extract of Mentha longifolia and Mentha pulegium were compared. GC-MS analysis of the essential oil identified 41 compounds constituting 96.66 and 96.13% of the total oil from M. longifolia and M. pulegium, respectively. The later oils were rich on pulegone (47.15 and 61.11%, respectively). Moreover, 1,8 cineole (11.54%), menthone (10.7%), α-pinene (3.57%), α-terpineol (3.17%) and d-cadinene (3.53%) were only present in M. longifolia oil, while isomenthone (17.02%), and piperitone (2.63%), were characteristic of M. pulegium oil. Shoot extract of the two species showed significantly different contents in total polyphenols (89.1 and 37.41 mg GAE/g DW), flavonoids (63.93 and 33.83 mg CE/g DW) and tannins (1.47 and 3.07 mg CE/g DW), respectively in M. longifolia and M. pulegium. The essential oils showed strong antimicrobial activity against all 16 microorganisms tested, whereas the methanol extracts were inactive. Moreover, the essential oils showed higher antioxidant activity than the methanolic extracts against the DPPH and superoxide radical scavenging. In fact, antioxidant activities of the oils were the same for both M. longifolia and M. pulegium against DPPH (IC₅₀ = 9 and 10 μg/ml, respectively) and 2-fold and 4-fold higher than shoot extracts (IC₅₀ = 20 and 48 μg/ml, respectively). Moreover, both oils showed the same antioxidative abilities as compared to the positive control (butylated hydroxytoluene). In the same way, the capacity to inhibit superoxide anion was very significant for the two oils (0.1 μg/ml for M. longifolia and 0.11 μg/ml for M. pulegium).     

Conjugated linoleic acid (CLA) prevents age-associated skeletal muscle loss

In this study, we examined the effect of CLA isomers in preventing age-associated muscle loss and the mechanisms underlying this effect, using 12-months-old C57BL/6 mice fed 10% corn oil (CO) or a diet supplemented with 0.5% c9t11-CLA, t10c12-CLA, or c9t11-CLA+t10c12-CLA (CLA-mix) for 6 months. Both t10c12-CLA and CLA-mix groups showed significantly higher muscle mass, as compared to CO and c9t11-CLA groups, measured by dual-energy X-ray absorptiometry and muscle wet weight. Enhanced mitochondrial ATP production, with higher membrane potential, and elevated muscle antioxidant enzymes (catalase and glutathione peroxidase) production, accompanied by slight increase in H₂O₂ production was noted in t10c12-CLA and CLA-mix groups, as compared to that of CO and c9t11-CLA groups. Oxidative stress, as measured by serum malondialdehyde and inflammation, as measured by LPS-treated splenocyte IL-6 and TNF-α, were significantly less in CLA isomers groups. Thus, CLA may be a novel dietary supplement that will prevent sarcopenia by maintaining redox balance during aging.     

Selective leishmanicidal effect of 1,3,4-thiadiazole derivatives and possible mechanism of action against Leishmania species

With the aim of determining selectivity and the possible target(s) of nitroheteroaryl-1,3,4-thiadiazoles considered as possible leads for the development of anti-leishmanial agents, we studied 5-nitroimidazole, 5-nitrofuran and 5-nitrothiophene analogs of N-substituted-piperazinyl-1,3,4-thiadiazoles. We investigated 21 representative compounds 1-3(a-g) for the following properties: selectivity and efficiency against different Leishmania wild type species and intracellular parasite, toxicity against host cells and inhibition of topoisomerases I and II. Our results indicate that the nitroimidazole analogs 1a and 1f, and nitrofuran derivatives 2a, 2b, 2c, 2f, and 2g exhibited low toxicity against the host cells (IC₅₀ ? 80 μM), but high selectivity against intracellular amastigotes (selectivity index > 12). Leishmania topoisomerases revealed impressive sensitivity to the agents (%inhibition >50 at IC₅₀ doses of compounds against Leishmania). Our findings showed that at least part of leishmaniacidal effect of the compounds could be attributed to disruption DNA-relaxed activities of topoisomerases I and II, and cleavable-complex formation.