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Displaying publications 21 - 25 of 25 in total

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Arbuscular mycorrhizal fungi influence belowground interactions between a specialist root-feeder and its natural enemy

Davidson-Lowe E, Zainuddin N, Trase O, McCarthy N, Ali JG

J Invertebr Pathol, 2024 Nov;207:108200.
PMID: 39374864 DOI: 10.1016/j.jip.2024.108200

As primary producers, plants play a central role in mediating interactions across trophic levels. Although plants are the primary food source for herbivorous insects, they can protect themselves from herbivore damage. Many plants produce toxic compounds that directly reduce herbivore feeding, but plants also protect themselves indirectly by attracting natural enemies of the attacking herbivore through volatile signaling. These so-called tri-trophic interactions have historically been documented aboveground in aerial plant parts but are also known to occur belowground in root systems. In addition to herbivores, plants directly interact with other organisms, which can influence the outcomes of tri-trophic interactions. Arbuscular mycorrhizal fungi (AMF) are symbiotic soil microbes that colonize the roots of plants and facilitate nutrient uptake. These microbes can alter plant chemistry and subsequent resistance to herbivores. Few studies, however, have shown how AMF affect tri-trophic interactions above- or belowground. This study examines how AMF colonization affects the emission of root volatiles when plants are under attack by western corn rootworm, a problematic pest of corn, and subsequent attraction of entomopathogenic nematodes, a natural enemy of western corn rootworm. Mycorrhizal fungi increased rootworm survival but decreased larval weight. Differences were detected across root volatile profiles, but there was not a clear link between volatile signaling and nematode behavior. Nematodes were more attracted to non-mycorrhizal plants without rootworms and AMF alone in soil, suggesting that AMF may interfere with cues that are used in combination with volatiles which nematodes use to locate prey.

Matched MeSH terms: Volatile Organic Compounds/analysis
Low-temperature and long-time heating regimes on non-volatile compound and taste traits of beef assessed by the electronic tongue system

Ismail I, Hwang YH, Joo ST

Food Chem, 2020 Aug 01;320:126656.
PMID: 32224424 DOI: 10.1016/j.foodchem.2020.126656

The influence of temperature-time combinations on non-volatile compound and taste traits of beef semitendinosus muscles tested by the electronic tongue was studied. Single-stage sous-vide at 60 and 70 °C (6 and 12 h), and two-stage sous-vide that sequentially cooked at 45 °C (3 h) and 60 °C (either 3 or 9 h) were compared with traditional cooking at 70 °C (30 min). Umami was better explained in the given model of partial least squares regression than astringency, sourness, saltiness, bitterness, and richness. Sous-vide at 70 °C for 12 h characterized the most umami, likely adenosine-5'-monophosphate (AMP) and guanosine-5'-monophosphate (GMP) as significant contributors. Two-stage sous-vide projected higher histidine, leucine, inosine, and hypoxanthine with the astringent and sour taste significant after 6 and 12 h cooking, respectively. Equivalent umami concentration (EUC) between umami amino acids and umami nucleotides showed a strong relationship to umami taste assessed by the electronic tongue.

Matched MeSH terms: Volatile Organic Compounds/analysis
Assessment of gas chromatography time-of-flight accurate mass spectrometry for identification of volatile and semi-volatile compounds in honey

Moniruzzaman M, Rodríguez I, Ramil M, Cela R, Sulaiman SA, Gan SH

Talanta, 2014 Nov;129:505-15.
PMID: 25127626 DOI: 10.1016/j.talanta.2014.06.019

The performance of gas chromatography (GC) combined with a hybrid quadrupole time-of-flight (QTOF) mass spectrometry (MS) system for the determination of volatile and semi-volatile compounds in honey samples is evaluated. After headspace (HS) solid-phase microextraction (SPME) of samples, the accurate mass capabilities of the above system were evaluated for compounds identification. Accurate scan electron impact (EI) MS spectra allowed discriminating compounds displaying the same nominal masses, but having different empirical formulae. Moreover, the use of a mass window with a width of 0.005 Da provided highly specific chromatograms for selected ions, avoiding the contribution of interferences to their peak areas. Additional information derived from positive chemical ionization (PCI) MS spectra and ion product scan MS/MS spectra permitted confirming the identity of novel compounds. The above possibilities are illustrated with examples of honey aroma compounds, belonging to different chemical classes and containing different elements in their molecules. Examples of compounds whose structures could not be described are also provided. Overall, 84 compounds, from a total of 89 species, could be identified in 19 honey samples from 3 different geographic areas in the world. The suitability of responses measured for selected ions, corresponding to above species, for authentication purposes is assessed through principal components analysis.

Matched MeSH terms: Volatile Organic Compounds/analysis*
Association Between Oral Hygiene Status and Halitosis Among Smokers and Nonsmokers

Jiun IL, Siddik SN, Malik SN, Tin-Oo MM, Alam MK, Khan MM

Oral Health Prev Dent, 2015;13(5):395-405.
PMID: 25789356 DOI: 10.3290/j.ohpd.a33920

PURPOSE: To study the association of smoking with poor oral hygiene status and halitosis in a comparative cross-sectional study.
MATERIALS AND METHODS: 100 smokers and 100 nonsmokers ages 18-50 years were recruited for this study in Kota Bharu, Malaysia. Oral hygiene (good/fair vs poor) was determined using the Simplified Oral Hygiene Index, and the halitosis level was measured using a Halimeter. Subjects were instructed to refrain from consuming foods containing garlic, onions, strong spices, alcohol and using mouthwashes 48 h prior to the examination. The halitosis levels were quantified by recording volatile sulphur compounds (VSCs) three times at 3-min intervals, resulting in a mean halitosis score. Various statistical analyses were performed, ranging from simple frequency analysis to multivariable modelling.
RESULTS: The proportions of subjects with poor oral hygiene and high halitosis were 24.0% and 41.5%, respectively. According to bivariate analyses, both problems were significantly less frequent among younger adults (halitosis), females, subjects with higher education, those with adequate habits to maintain good oral hygiene, those who had recent dental visits and those self-reporting fewer health problems. The percentages of poor oral hygiene and high halitosis were significantly higher in smokers (p < 0.001). However, almost all these variables failed to show significance in the multivariate analyses, with the exceptions of smoking for both poor oral hygiene and halitosis, education for poor oral hygiene, and age, self-reported health problems and time since the previous dental visit for halitosis.
CONCLUSION: These findings demonstrate a significantly higher level of halitosis and poorer oral hygiene in smokers than nonsmokers.

Matched MeSH terms: Volatile Organic Compounds/analysis
Bioremediation of PAHs and VOCs: Advances in clay mineral-microbial interaction

Biswas B, Sarkar B, Rusmin R, Naidu R

Environ Int, 2015 Dec;85:168-81.
PMID: 26408945 DOI: 10.1016/j.envint.2015.09.017

Bioremediation is an effective strategy for cleaning up organic contaminants, such as polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). Advanced bioremediation implies that biotic agents are more efficient in degrading the contaminants completely. Bioremediation by microbial degradation is often employed and to make this process efficient, natural and cost-effective materials can serve as supportive matrices. Clay/modified clay minerals are effective adsorbents of PAHs/VOCs, and readily available substrate and habitat for microorganisms in the natural soil and sediment. However, the mechanism underpinning clay-mediated biodegradation of organic compounds is often unclear, and this requires critical investigation. This review describes the role of clay/modified clay minerals in hydrocarbon bioremediation through interaction with microbial agents in specific scenarios. The vision is on a faster, more efficient and cost-effective bioremediation technique using clay-based products. This review also proposes future research directions in the field of clay modulated microbial degradation of hydrocarbons.

Matched MeSH terms: Volatile Organic Compounds/analysis*