| metagenomic sequencing provides insights into microbial detoxification in the guts of small mammalian herbivores (neotoma spp.). | microbial detoxification of plant toxins influences the use of plants as food sources by herbivores. stephen's woodrats (neotoma stephensi) specialize on juniper, which is defended by oxalate, phenolics and monoterpenes, while closely related n. albigula specialize on cactus, which only contains oxalate. woodrats maintain two gut chambers harboring dense microbial communities: a foregut chamber proximal to the major site of toxin absorption, and a cecal chamber in their hindgut. we performed sev ... | 2018 | 30202961 |
| terpenes may serve as feeding deterrents and foraging cues for mammalian herbivores. | terpenes, volatile plant secondary compounds produced by woody plants, have historically been thought to act as feeding deterrents for mammalian herbivores. however, three species of woodrats, neotoma stephensi, n. lepida, and n. albigula, regularly consume juniper, which is high in terpenes, and n. stephensi and n. lepida are considered juniper specialists. by investigating the terpene profiles in juniperus monosperma and j. osteosperma, which are browsed or avoided by woodrats in the field, an ... | 2019 | 31755019 |
| strategies in herbivory by mammals revisited: the role of liver metabolism in a juniper specialist (neotoma stephensi) and a generalist (neotoma albigula). | although herbivory is widespread among mammals, few species have adopted a strategy of dietary specialization. feeding on a single plant species often exposes herbivores to high doses of plant secondary metabolites (psms), which may exceed the animal's detoxification capacities. theory predicts that specialists will have unique detoxification mechanisms to process high levels of dietary toxins. to evaluate this hypothesis, we compared liver microsomal metabolism of a juniper specialist, neotoma ... | 2020 | 32246507 |
| diet breadth of mammalian herbivores: nutrient versus detoxification constraints. | two hypotheses, nutrient constraints and detoxification limitation, have been proposed to explain the lack of specialists among mammalian herbivores. the nutrient constraint hypothesis proposes that dietary specialization in mammalian herbivores is rare because no one plant can provide all requisite nutrients. the detoxification limitation hypothesis suggests that the mammalian detoxification system is incapable of detoxifying high doses of similar secondary compounds present in a diet of a sing ... | 2000 | 28308595 |
| ingestion of plant secondary compounds causes diuresis in desert herbivores. | plant secondary compounds are recognized deterrents and toxins to a variety of herbivores. the effect of secondary compounds on water balance of herbivores is virtually unexplored, yet secondary compounds could potentially cause a decrease in an animal's ability to maintain water balance. we investigated the effects of secondary compounds, alpha-pinene and creosote resin, on water balance in three species of herbivorous woodrats (neotoma stephensi, n. albigula, n. lepida). in separate experiment ... | 2002 | 28547260 |
| elimination of plant toxins by herbivorous woodrats: revisiting an explanation for dietary specialization in mammalian herbivores. | constraints on rates of detoxification and elimination of plant toxins are thought to be responsible for limiting dietary specialization in mammalian herbivores. this hypothesis, known as the detoxification limitations hypothesis, suggests that most mammalian herbivores are generalists to avoid overdosing on toxins from a single plant species. the hypothesis also predicts that the few mammalian specialists that exist should have adaptations for rapid detoxification and elimination of plant secon ... | 2003 | 12647185 |
| woodrat (neotoma) herbivores maintain nitrogen balance on a low-nitrogen, high-phenolic forage, juniperus monosperma. | the acquisition of adequate quantities of nitrogen is a challenge for herbivorous vertebrates because many plants are in low nitrogen and contain secondary metabolites that reduce nitrogen digestibility. to investigate whether herbivores maintain nitrogen balance on plant diets low in nitrogen and high in secondary compounds, we studied the effect of juniper (juniperus monosperma) ingestion on the nitrogen balance of two species of herbivorous woodrats (neotoma stephensi and n. albigula). these ... | 2005 | 15926043 |
| xenobiotic metabolism of plant secondary compounds in juniper (juniperus monosperma) by specialist and generalist woodrat herbivores, genus neotoma. | mammalian herbivores routinely consume diets laden with often-toxic xenobiotics, yet the manner in which mammalian herbivores detoxify these plant secondary compounds (psc) is largely unknown. theory predicts that specialists rely more heavily on functionalization pathways whereas generalists rely on conjugation pathways to metabolize psc in their diet. we took a pharmacological approach to determine how a specialist (neotoma stephensi) of juniper foliage (juniperus monosperma) and a generalist ... | 2007 | 17681888 |
| patterns of host gene expression associated with harboring a foregut microbial community. | harboring foregut microbial communities is considered a key innovation that allows herbivorous mammals to colonize new ecological niches. however, the functions of these chambers have only been well studied at the molecular level in ruminants. here, we investigate gene expression in the foregut chamber of herbivorous rodents and ask whether these gene expression patterns are consistent with results in ruminants. we compared gene expression in foregut tissues of two rodent species: stephen's wood ... | 2017 | 28874116 |
| ingestion of juniper foliage reduces metabolic rates in woodrat (neotoma) herbivores. | ingestion of plant secondary compounds by herbivores is predicted to increase resting or basal metabolic rates. we tested this hypothesis with two species of woodrat herbivores, neotoma stephensi and neotoma albigula, consuming diets of juniper (juniperus monosperma), which is rich in plant secondary compounds. in nature, n. stephensi specializes on juniper, whereas n. albigula consumes a variety of plant species including juniper. we measured resting metabolic rates (rmr) of woodrats on control ... | 2003 | 16351900 |
| differential hepatic gene expression of a dietary specialist (neotoma stephensi) and generalist (neotoma albigula) in response to juniper (juniperus monosperma) ingestion. | dietary specialization is thought to be rare in mammalian herbivores because of limitations of their detoxification system in processing large doses of a single type of plant secondary compound (psc). therefore, in order to specialize on a single species of plant, mammalian herbivores must have a highly efficient detoxification system for the particular types of pscs they ingest. using microarray technology, we looked at the expression of hepatic genes of a dietary specialist, neotoma stephensi, ... | 2007 | 20483276 |
| captivity results in disparate loss of gut microbial diversity in closely related hosts. | the gastrointestinal tracts of animals contain diverse communities of microbes that provide a number of services to their hosts. there is recent concern that these communities may be lost as animals enter captive breeding programmes, due to changes in diet and/or exposure to environmental sources. however, empirical evidence documenting the effects of captivity and captive birth on gut communities is lacking. we conducted three studies to advance our knowledge in this area. first, we compared ch ... | 2014 | 27293630 |
| Testing the diet-breadth trade-off hypothesis: differential regulation of novel plant secondary compounds by a specialist and a generalist herbivore. | Specialist herbivores are predicted to have evolved biotransformation pathways that can process large doses of secondary compounds from the plant species on which they specialize. It is hypothesized that this physiological specialization results in a trade-off such that specialists may be limited in ability to ingest novel plant secondary compounds (PSCs). In contrast, the generalist foraging strategy requires that herbivores alternate consumption of plant species and PSC types to reduce the pos ... | 2011 | 21927911 |
| is alpha-pinene a substrate for permeability-glycoprotein in wood rats? | alpha-pinene is the dominant monoterpene in juniperus monosperma. wood rat species in the genus neotoma that consume j. monosperma vary in their inclusion of it in their wild diet and in their tolerance of whole j. monosperma or alpha-pinene in laboratory feeding trials. a proposed mechanism for variable tolerance is a difference in absorption of alpha-pinene from the small intestine that is mediated by the intestinal transporter permeability glycoprotein (pgp). to determine if alpha-pinene is a ... | 2006 | 16770713 |
| liver biotransforming enzymes in woodrats neotoma stephensi (muridae). | mammalian herbivores are exposed to extremely high levels of plant secondary compounds naturally present in their diet. it has been speculated that specialist herbivores should express a unique pattern of biotransforming enzymes to permit the consumption of a single species of toxic plant. specifically, specialists should rely on pathways that effectively biotransform the toxins they routinely encounter in their diet. we examined the hepatic mrna expression and activity or content of biotransfor ... | 2004 | 15450867 |
| a specialist herbivore (neotoma stephensi) absorbs fewer plant toxins than does a generalist (neotoma albigula). | detoxification capacity of enzymes in the liver is thought to be the primary factor governing dietary toxin intake by mammalian herbivores. recently, toxin absorption in the gut was proposed as an alternative process that also influences toxin intake. we examined the role of the gut in regulating toxin absorption by quantifying excretion of a plant secondary compound in the feces. we hypothesized that specialists have a greater capacity to reduce intestinal absorption of toxins than do generalis ... | 2012 | 15057724 |
| effects of consumption of juniper (juniperus monosperma) on cost of thermoregulation in the woodrats neotoma albigula and neotoma stephensi at different acclimation temperatures. | a study was done to test whether toxic plants that occur naturally in the diet affect thermoregulation in mammalian herbivores. the woodrats neotoma albigula and neotoma stephensi both consume juniper (juniperus monosperma), a plant with high levels of toxic compounds. body temperature (tb), basal metabolic rate (bmr), and the minimum cost of thermogenesis (cmin) were measured for both species on control and juniper diets following warm (25 degrees c) and cold (18 degrees c) acclimation. in n. a ... | 2006 | 15095250 |
| intestinal capacity of p-glycoprotein is higher in the juniper specialist, neotoma stephensi, than the sympatric generalist, neotoma albigula. | permeability-glycoprotein (pgp) is a membrane-bound, atp-dependent, transport protein that excludes many cytotoxic compounds including plant metabolites and pollutants from the barrier epithelia of many tissues including the small intestine. we hypothesized that intestinal pgp capacity would be higher in neotoma stephensi, a specialist on juniperus monosperma known to be high in plant toxins, than the sympatric generalist, neotoma albigula, which consumes juniper in the field, but is unable to t ... | 2004 | 15556388 |
| differential expression and activity of catechol-o-methyl transferase (comt) in a generalist (neotoma albigula) and juniper specialist (neotoma stephensi) woodrat. | mammalian herbivores, particularly dietary specialists must have an efficient means to metabolize the high doses of plant secondary compounds they consume. we found previously that neotoma stephensi, a juniper specialist, upregulated catechol-o-methyl transferase (comt) mrna almost seven fold in response to an ecologically relevant diet (70% juniper). to further investigate the relevance of this enzyme with respect to juniper metabolism, we compared the protein expression, activity and kinetics ... | 2011 | 21820082 |