Metabolism of 14C-Labeled Octadecane by Cattle2

Bartley, E.E.; Helmer, L.G.; Meyer, Rikke Louise

doi:10.2527/jas1971.3361351x

Cited by 11 publications

(9 citation statements)

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“…To this respect, our results strongly suggested that ruminal bacteria are not able to synthesize n-alkanes from other wax components, and that they are not metabolized by the ruminal microbiota. The same conclusion was reached in vivo by McCarthy (1964) and Bartley et al (1971), working with 14 C-octadecane in goats and cattle, respectively, although they found high concentrations of the hydrocarbon in isolated bacterial extracts. Their hypothesis was that ruminal bacteria may incorporate alkanes in their Bq 5 becquerel; T1 5 incubation of labelled ryegrass free of wax components; T2 5 incubation of labelled n-alkanes; T3 5 incubation of labelled n-alkane-free waxes.…”

Section: Discussionsupporting

confidence: 72%

“…Longchain n-alkanes have also been used as duodenal flow (Askar et al, 2005) or rumen transit markers (Girá ldez et al, 2004), but whether the rumen microbes are able to synthesize and/or degrade them in anaerobic conditions remains a question to be answered before these hydrocarbons can be confidently used for these purposes. McCarthy (1964) and Bartley et al (1971) demonstrated that rumen bacteria from sheep and goats are able to incorporate 14 C-labelled octadecane (C 18 ) in their lipids. Evidence for bacterial metabolism of the incorporated alkane was discounted because of the absence of radioactivity appearing in volatile fatty acids (VFA), and also because of the anaerobic conditions prevailing in the rumen.…”

Section: Introductionmentioning

confidence: 99%

“…Oxygen is needed to form the hydroxyl group required for the oxidation of n-alkanes (Sporman and Widdel, 2000). Although many species of bacteria and fungi may oxidize short-chain alkanes (Radwan and Sorkhoh, 1993;Sporman and Widdel, 2000), none has been isolated in the rumen (Ohajuruka and Palmquist, 1991 Published papers agree about the dietary origin of tissue n-alkanes in a variety of animal species Bories, 1975a and1975b;Di Muccio et al, 1984;Tejeda et al, 2001;Petró n et al, 2004) although only a few have dealt specifically with this matter in ruminants (Bartley et al, 1971;Mayes et al, 1988;Ohajuruka and Palmquist, 1991). In rats, radioactive 14 C 29 can be transformed in long-chain fatty acids, cholesterol esters, di-and tri-glicerides or phospholipids in the liver (Kolattukudy and Hankin, 1966).…”

Section: Introductionmentioning

confidence: 99%

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In vitro studies of the metabolism of [14C]-n-alkanes using ruminal fluid of sheep as substrate

Keli

Mayes²,

Vega

2008

Animal

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Whether the rumen microbes are able to synthesize and/or degrade long-chain alkanes in anaerobic conditions remains a question to be answered before these hydrocarbons can be confidently used as duodenal flow or rumen transit markers. In this context, an experiment in vitro was carried out to establish whether within a rumen liquor fermentation system, n-alkanes can be derived from de-waxed structures of the plant or from non-alkane wax components (long-chain fatty alcohols, long-chain fatty acids and esters), or may be metabolized by bacteria to other components or to shorter-chain hydrocarbons. Ryegrass was labelled with 14 C in growth chambers under controlled conditions in order to use it as a substrate. The labelled material obtained was separated in three fractions: labelled alkanes, labelled de-waxed plant and labelled wax components without the alkanes. These fractions were used for three different incubations in vitro, which objectives were as follows: 1. To check whether rumen bacteria can synthesize alkanes from carbon structures other than waxes (e.g. sugars). 2. To verify whether rumen bacteria can metabolize the n-alkanes to other compounds. 3. To check whether rumen bacteria can synthesize n-alkanes from other carbon compounds from waxes. The results showed that there was neither bacterial synthesis nor metabolism of the n-alkanes in in vitro conditions.

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Section: Discussionsupporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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In vitro studies of the metabolism of [14C]-n-alkanes using ruminal fluid of sheep as substrate

Keli

Mayes²,

Vega

2008

Animal

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“…n -Alkanes are saturated aliphatic hydrocarbon chains naturally present in plant cuticular wax. They have a high fecal recovery in ruminants depending on the carbon chain length [8], [9], are neither degraded nor synthesized in the rumen [10], [11], and their analytical determination is sensitive and specific [7]; hence, they possess close-to-ideal tracer characteristics.…”

Section: Introductionmentioning

confidence: 99%

Stable Isotope Labeled n-Alkanes to Assess Digesta Passage Kinetics through the Digestive Tract of Ruminants

et al. 2013

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We describe the use of carbon stable isotope (13C) labeled n-alkanes as a potential internal tracer to assess passage kinetics of ingested nutrients in ruminants. Plant cuticular n-alkanes originating from intrinsically 13C labeled ryegrass plants were pulse dosed intraruminally in four rumen-cannulated lactating dairy cows receiving four contrasting ryegrass silage treatments that differed in nitrogen fertilization level (45 or 90 kg nitrogen ha−1) and maturity (early or late). Passage kinetics through the gastrointestinal tract were derived from the δ13C (i.e. the ratio 13C:12C) in apparently undigested fecal material. Isotopic enrichment was observed in a wide range of long-chain n-alkanes (C27–C36) and passage kinetics were determined for the most abundant C29, C31 and C33 n-alkanes, for which a sufficiently high response signal was detected by combustion isotope ratio mass spectrometry. Basal diet treatment and carbon chain length of n-alkanes did not affect fractional passage rates from the rumen (K 1) among individual n-alkanes (3.71–3.95%/h). Peak concentration time and transit time showed a quantitatively small, significant (p≤0.002) increase with carbon chain length. K 1 estimates were comparable to those of the 13C labeled digestible dry matter fraction (3.38%/h; r = 0.61 to 0.71; p≤0.012). A literature review has shown that n-alkanes are not fermented by microorganisms in the rumen and affirms no preferential depletion of 13C versus 12C. Our results suggest that 13C labeled n-alkanes can be used as nutrient passage tracers and support the reliability of the δ13C signature of digestible feed nutrients as a tool to measure nutrient-specific passage kinetics.

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“…However, the ubiquity of alkanes as natural compounds in the marine environment, coupled with the low concentrations and limited trophic transfer in the sea otter food web (mean AE SD: BSAF 0.37 AE 0.33, BMF 1.19 AE 1.68; Supplemental Data, Tables 1 and 2), suggests a limited health risk for this class of compounds. These compounds are readily used in lipid synthesis pathways or undergo rapid elimination in vertebrates [38,39]. Conversely, PAHs are known to exert toxicity via multiple mechanisms in vertebrates [40], so we explored the movement of these compounds in a series of dietary scenarios for sea otters in BC.…”

Section: Characterizing Hydrocarbons In the Food Web Of Sea Ottersmentioning

confidence: 99%

Hydrocarbon concentrations and patterns in free‐ranging sea otters (Enhydra lutris) from British Columbia, Canada

Harris

Nichol

Ross

2011

Enviro Toxic and Chemistry

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With oil pollution recognized as a major threat to British Columbia's recovering sea otter (Enhydra lutris) population, it is important to distinguish acute from chronic exposures to oil constituent groups in this marine mammal. Concentrations and patterns of alkanes and polycyclic aromatic hydrocarbons (PAHs) were determined in blood samples from 29 live-captured sea otters in two coastal areas of British Columbia, as well as in representative samples of their invertebrate prey. Hydrocarbon concentrations in sea otters were similar between areas and among age and sex classes, suggesting that metabolism dominates the fate of these compounds in sea otters. Biomagnification factors derived from PAH ratios in otter:prey supported this notion. Although some higher alkylated three- and four-ring PAHs appeared to biomagnify, the majority of PAHs did not. The apparent retention of alkyl PAHs was reflected in the composition of estimated sea otter body burdens, which provided an alternative way of evaluating hydrocarbon exposure. Alkyl PAHs made up 86 ± 9% of estimated body burdens (4,340 ± 2,950 µg), with no differences between males and females (p = 0.18). The importance of measuring both parent and alkyl PAHs is underscored by their divergent dynamics in sea otters, with ready depuration of parent PAHs (metabolized or excreted) by sea otters on the one hand and biomagnification of alkyl PAHs on the other.

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Metabolism of 14C-Labeled Octadecane by Cattle2

Cited by 11 publications

References 0 publications

In vitro studies of the metabolism of [14C]-n-alkanes using ruminal fluid of sheep as substrate

In vitro studies of the metabolism of [14C]-n-alkanes using ruminal fluid of sheep as substrate

Stable Isotope Labeled n-Alkanes to Assess Digesta Passage Kinetics through the Digestive Tract of Ruminants

Hydrocarbon concentrations and patterns in free‐ranging sea otters (Enhydra lutris) from British Columbia, Canada

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