Plant poisoning in free-living wild animals: a review

Tick-borne piroplasms and trypanosomes incidentally detected in eastern grey kangaroos (Macropus giganteus) during a mortality and morbidity event in southern New South Wales, Australia

Tick-borne haemoparasites, including piroplasms and trypanosomes, are almost ubiquitous in Australian wildlife, with some associated with health impacts to individual animals and declining wildlife populations. An array of ecologically distinct piroplasm and trypanosome species occur throughout Australia although many of these species and their sylvatic ecologies are poorly characterised. Between May 2022 and October 2023, an anecdotally reported localised eastern grey kangaroo (Macropus giganteus) morbidity/mortality event occurred in coastal southern New South Wales, Australia, characterised by animals presenting with blindness, emaciation, lethargy, ataxia, and astasia. Here we used molecular techniques to identify tick-borne piroplasms (Babesia and Theileria) and trypanosomes in affected animals. Blood (n = 89) and liver (n = 19) samples were collected after the humane euthanasia of wild animals due to welfare concerns, and brief notes on the animal's health were recorded. In total, 20 (22.5%) animals were infected with tick-borne haemoparasites, including a novel Theileria sp. nov. (14, 15.7%), Babesia macropus (2, 2.2%), Trypanosoma gilletti (5, 5.6%), and Trypanosoma vegrandis (1, 1.1%). Liver samples were also screened for Wallal and Warego viruses due to animals' blindness, but were negative. This is the first report of T. gilletti and T. vegrandis in eastern grey kangaroos, although they have been previously reported in high numbers in ticks which commonly parasites this host. The novel Theileria sp. was previously reported in questing Ixodes holocyclus and in ticks from an opportunistically collected eastern grey kangaroo and red-necked wallaby (Notamacropus rufogriseus). However, we show for the first time this Theileria sp. can occur widely in eastern grey kangaroos. Ultimately, this small study did not intend, and is not able to draw inference regarding the pathogenicity of these haemoparasites to eastern grey kangaroos and it is likely that other factors, such as chronic Phalaris grass toxicity, had a role in this localised mortality/morbidity event.

Chronic phalaris toxicity in macropods is widespread and peaks in July in Victoria, Australia

Phalaris aquatica is pasture species introduced into Australia during early European settlement. Consumption of the plant can cause the neurological condition chronic phalaris toxicity (CPT) in sheep and cattle. In recent years, there has been an increase in reports of CPT in macropods, which has raised concerns regarding its impacts on their welfare. Currently, little is known about the distribution or seasonal patterns of this disease in wildlife, information pivotal in assessing its potential risks. Between 2021 and 2022, we conducted a survey targeting government bodies, veterinary businesses and wildlife organisations to investigate the locations and time of occurrence of CPT in macropods in the state of Victoria, Australia. We received 13 survey responses, 12 verbal reports, a full record of investigated cases from a university veterinary school and cases from a wildlife rescue organisation. Over the period of 11 years, Victoria had 918 cases of CPT recorded in macropods from 36 local government areas, with cases concentrated centrally just north of the state capital of Melbourne and July (midwinter) being the month with the highest case count (n = 220). There was a significant positive correlation between case count and both the abundance of kangaroos (Macropus giganteus and Macropus fuliginosus) (P < 0.01) and the abundance of P. aquatica (P = 0.009), and a significant negative correlation between annual case count and average rainfall of March (P = 0.016) and April (P = 0.02). Understanding these relationships will assist land and wildlife managers in predicting the risk and magnitude of disease outbreaks of CPT each in Victoria.

Traces of dietary patterns in saliva of hominids: Profiling salivary amino acid fingerprints in great apes and humans

Herbivorous animals that regularly consume tannin-rich food are known to secrete certain tannin-binding salivary proteins (TBSPs), especially proline-rich proteins and histidine-rich proteins, as an effective measure to counteract the antinutritive effects of dietary tannins. Due to their high binding capacity, TBSPs complex with tannins in the oral cavity, and thereby protect dietary proteins and digestive enzymes. Although the natural diet of great apes (Hominidae) is biased toward ripe fruits, analyses of food plants revealed that their natural diet contains considerable amounts of tannins, which is raising the question of possible counter-measures to cope with dietary tannins. In our study, we investigated the salivary amino acid profiles of zoo-housed Pan paniscus, Pan troglodytes, Gorilla gorilla, and Pongo abelii, and compared their results with corresponding data from Homo sapiens. Individual saliva samples of 42 apes and 17 humans were collected and quantitated by amino acid analysis, using cation-exchange chromatography with postcolumn derivatization, following acid hydrolysis. We found species-specific differences in the salivary amino acid profiles with average total salivary protein concentration ranging from 308.8 mg/dL in Po. abelii to 1165.6 mg/dL in G. gorilla. Total salivary protein was consistently higher in ape than in human saliva samples (174 mg/dL). All apes had on average also higher relative proline levels than humans did. Histidine levels had the highest concentration in the samples from Po. abelii followed by P. paniscus. In all ape species, the high salivary concentrations of proline and histidine are considered to be indicative of high concentrations of TBSPs in hominids. Given that the species differences in salivary composition obtained in this study correspond with overall patterns of secondary compound content in the diet of wild populations, we assume that salivary composition is resilient to acute and long-lasting changes in diet composition in general and tannin content in particular.

Mule deer do more with less: comparing their nutritional requirements and tolerances with white-tailed deer

Congeneric species often share ecological niche space resulting in competitive interactions that either limit co-occurrence or lead to niche partitioning. Differences in fundamental nutritional niches mediated through character displacement or isolation during evolution are potential mechanisms that could explain overlapping distribution patterns of congenerics. We directly compared nutritional requirements and tolerances that influence the fundamental niche of mule (Odocoileus hemionus) and white-tailed deer (O. virginianus), which occur in allopatry and sympatry in similar realized ecological niches across their ranges in North America. Digestible energy and protein requirements and tolerances for plant fiber and plant secondary metabolites (PSMs) of both deer species were quantified using in vivo digestion and intake tolerance trials with six diets ranging in content of fiber, protein, and PSMs using tractable deer raised under identical conditions in captivity. We found that compared with white-tailed deer, mule deer required 54% less digestible protein and 21% less digestible energy intake per day to maintain body mass and nitrogen balance. In addition, they had higher fiber, energy, and dry matter digestibility and produced glucuronic acid (a byproduct of PSM detoxification) at a slower rate when consuming the monoterpene α-pinene. The mule deers’ enhanced physiological abilities to cope with low-quality, chemically defended forages relative to white-tailed deer might minimize potential competitive interactions in shared landscapes and provide a modest advantage to mule deer in habitats dominated by low-quality forages.

Bioaccumulation and Distribution of Indospicine and Its Foregut Metabolites in Camels Fed Indigofera spicata

In vitro experiments have demonstrated that camel foregut-fluid has the capacity to metabolize indospicine, a natural toxin which causes hepatotoxicosis, but such metabolism is in competition with absorption and outflow of indospicine from the different segments of the digestive system. Six young camels were fed Indigofera spicata (337 µg indospicine/kg BW/day) for 32 days, at which time three camels were euthanized. The remaining camels were monitored for a further 100 days after cessation of this indospicine diet. In a retrospective investigation, relative levels of indospicine foregut-metabolism products were examined by UHPLC-MS/MS in plasma, collected during both accumulation and depletion stages of this experiment. The metabolite 2-aminopimelamic acid could be detected at low levels in almost all plasma samples, whereas 2-aminopimelic acid could not be detected. In the euthanized camels, 2-aminopimelamic acid could be found in all tissues except muscle, whereas 2-aminopimelic acid was only found in the kidney, pancreas, and liver tissues. The clearance rate for these metabolites was considerably greater than for indospicine, which was still present in plasma of the remaining camels 100 days after cessation of Indigofera consumption.

The balancing act of foraging: mammalian herbivores trade-off multiple risks when selecting food patches

Animals face multiple risks while foraging such as the risk of acquiring inadequate energy from food and the risk of predation. We evaluated how two sympatric rabbits (pygmy rabbits, Brachylagus idahoensis, and mountain cottontail rabbits, Sylvilagus nuttallii) that differ in size, use of burrows, and habitat specialization in the sagebrush-steppe of western North America respond to different types and levels of perceived risks (i.e., fitness cost × probability of occurrence), including fiber and toxins in food, exposure to predation, and distance from a refuge. We measured food intake by the rabbits at paired food patches that varied in these risks and used the method of paired comparisons to create a relative ranking of habitat cues, which revealed an animal's perceived risk on a single scale representing an integrated response to a variety of risks. Pygmy rabbits perceived exposure to predation risk and distance from a burrow as riskier than did cottontails, whereas cottontails perceived dietary toxin as riskier. Pygmy rabbits consumed lower quality food, containing higher fiber or toxins, thereby avoided feeding in exposed patches or traveling far from their burrow to forage. In contrast, cottontails fed in exposed patches and traveled farther from the burrow to obtain higher quality food. We have shown how risks can be integrated into a single model that allows animals to reveal their perceptions of risks on a single scale that can be used to create a spatially explicit landscape of risk.

Thermo-alkaline Treatment as a Practical Degradation Strategy To Reduce Indospicine Contamination in Camel Meat

Ingestion of indospicine-contaminated camel and horse meat has caused fatal liver injury to dogs in Australia, and it is currently not known if such contaminated meat may pose a human health risk upon dietary exposure. To date, indospicine-related research has tended to focus on analytical aspects, with little information on post-harvest management of indospicine-contaminated meat. In this study, indospicine degradation was investigated in both aqueous solution and also contaminated meat, under a range of conditions. Aqueous solutions of indospicine and indospicine-contaminated camel meat were microwaved (180 °C) or autoclaved (121 °C) with the addition of food-grade additives [0.05% (v/v) acetic acid or 0.05% (w/v) sodium bicarbonate] for 0, 15, 30, and 60 min. An aqueous sodium bicarbonate solution demonstrated the greatest efficacy in degrading indospicine, with complete degradation after 15 min of heating in a microwave or autoclave; concomitant formation of indospicine degradation products, namely, 2-aminopimelamic and 2-aminopimelic acids, was observed. Similar treatment of indospicine-contaminated camel meat with aqueous sodium bicarbonate resulted in 50% degradation after 15 min of heating in an autoclave and 100% degradation after 15 min of heating in a microwave. The results suggest that thermo-alkaline aqueous treatment has potential as a pragmatic post-harvest handling technique in reducing indospicine levels in indospicine-contaminated meat.

POISONING BY THE SWAINSONINE-CONTAINING PLANT SIDA CARPINIFOLIA IN CAPTIVE SAMBAR DEER (CERVUS UNICOLOR)

Plant intoxications in wildlife are difficult to diagnose, are overlooked, or are sometimes even neglected. Hence, factors that induce wild animals to ingest poisonous plants have not been sufficiently documented. An outbreak of glycoprotein storage disease in sambar deer ( Cervus unicolor ), induced by ingestion of the swainsonine-containing plant, common wireweed (Sida carpinifolia), is reported. Nine out of 55 deer held by a zoo in Brazil were affected. The poisoning was characterized by emaciation and neurologic signs followed by unexpected death in some of the animals. Animals presented abnormal consciousness, posterior paresis, and musculoskeletal weakness; less evident were vestibulo-cerebellar signs. Histologically, there was vacuolation of neurons and epithelial cells of the pancreatic acines, thyroid follicules, and renal tubules. Furthermore, in the central nervous system were axonal degeneration, necrosis, and loss of neurons. Three factors may lead to the ingestion of S. carpinifolia by sambar deer: 1) A grazing field with only S. carpinifolia as a source of forage; 2) a large number of animals kept in this field; and 3) a hierarchy within a cervid group in which dominant males isolated and displaced juvenile and weaker adult males, leaving them with access to only S. carpinifolia.

Accumulation, Persistence, and Effects of Indospicine Residues in Camels Fed Indigofera Plant

Indospicine (l-2-amino-6-amidinohexanoic acid) is a natural hepatotoxin found in all parts of some Indigofera plants such as Indigofera linnaei and Indigofera spicata. Several studies have documented a susceptibility to this hepatotoxin in different species of animals, including cattle, sheep, dogs, and rats, which are associated with mild to severe liver disease after prolonged ingestion. However, there is little published data on the effects of this hepatotoxin in camels, even though Indigofera plants are known to be palatable to camels in central Australia. The secondary poisoning of dogs after prolonged dietary exposure to residual indospicine in camel muscle has raised additional food safety concerns. In this study, a feeding experiment was conducted to investigate the in vivo accumulation, excretion, distribution, and histopathological effects of dietary indospicine on camels. Six young camels (2-4 years old), weighing 270-390 kg, were fed daily a roughage diet consisting of Rhodes grass hay and lucerne chaff, supplemented with Indigofera and steam-flaked barley. Indigofera (I. spicata) was offered at 597 mg DM/kg body weight (bw)/day, designed to deliver 337 μg indospicine/kg bw/day, and fed for a period of 32 days. Blood and muscle biopsies were collected over the period of the study. Concentrations of indospicine in the plasma and muscle biopsy samples were quantitated by validated ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The highest concentrations in plasma (1.01 mg/L) and muscle (2.63 mg/kg fresh weight (fw)) were found at necropsy (day 33). Other tissues were also collected at necropsy, and analysis showed ubiquitous distribution of indospicine, with the highest indospicine accumulation detected in the pancreas (4.86 ± 0.56 mg/kg fw) and liver (3.60 ± 1.34 mg/kg fw), followed by the muscle, heart, and kidney. Histopathological examination of liver tissue showed multiple small foci of predominantly mononuclear inflammatory cells. After cessation of Indigofera intake, indospicine present in plasma in the remaining three camels had a longer terminal elimination half-life (18.6 days) than muscle (15.9 days), and both demonstrated monoexponential decreases.

Modeling trade-offs between plant fiber and toxins: a framework for quantifying risks perceived by foraging herbivores

When selecting habitats, herbivores must weigh multiple risks, such as predation, starvation, toxicity, and thermal stress, forcing them to make fitness trade-offs. Here, we applied the method of paired comparisons (PC) to investigate how herbivores make trade-offs between habitat features that influence selection of food patches. The method of PC measures utility and the inverse of utility, relative risk, and makes trade-offs and indifferences explicit by forcing animals to make choices between two patches with different types of risks. Using a series of paired-choice experiments to titrate the equivalence curve and find the marginal rate of substitution for one risk over the other, we evaluated how toxin-tolerant (pygmy rabbit Brachylagus idahoensis) and fiber-tolerant (mountain cottontail rabbit Sylviagus nuttallii) herbivores differed in their hypothesized perceived risk of fiber and toxins in food. Pygmy rabbits were willing to consume nearly five times more of the toxin 1,8-cineole in their diets to avoid consuming higher levels of fiber than were mountain cottontails. Fiber posed a greater relative risk for pygmy rabbits than cottontails and cineole a greater risk for cottontails than pygmy rabbits. Our flexible modeling approach can be used to (1) quantify how animals evaluate and trade off multiple habitat attributes when the benefits and risks are difficult to quantify, and (2) integrate diverse risks that influence fitness and habitat selection into a single index of habitat value. This index potentially could be applied to landscapes to predict habitat selection across several scales.

Macroevolution of venom apparatus innovations in auger snails (Gastropoda; Conoidea; Terebridae)

The Terebridae are a diverse family of tropical and subtropical marine gastropods that use a complex and modular venom apparatus to produce toxins that capture polychaete and enteropneust preys. The complexity of the terebrid venom apparatus suggests that venom apparatus development in the Terebridae could be linked to the diversification of the group and can be analyzed within a molecular phylogenetic scaffold to better understand terebrid evolution. Presented here is a molecular phylogeny of 89 terebrid species belonging to 12 of the 15 currently accepted genera, based on Bayesian inference and Maximum Likelihood analyses of amplicons of 3 mitochondrial (COI, 16S and 12S) and one nuclear (28S) genes. The evolution of the anatomy of the terebrid venom apparatus was assessed by mapping traits of six related characters: proboscis, venom gland, odontophore, accessory proboscis structure, radula, and salivary glands. A novel result concerning terebrid phylogeny was the discovery of a previously unrecognized lineage, which includes species of Euterebra and Duplicaria. The non-monophyly of most terebrid genera analyzed indicates that the current genus-level classification of the group is plagued with homoplasy and requires further taxonomic investigations. Foregut anatomy in the family Terebridae reveals an inordinate diversity of features that covers the range of variability within the entire superfamily Conoidea, and that hypodermic radulae have likely evolved independently on at least three occasions. These findings illustrate that terebrid venom apparatus evolution is not perfunctory, and involves independent and numerous changes of central features in the foregut anatomy. The multiple emergence of hypodermic marginal radular teeth in terebrids are presumably associated with variable functionalities, suggesting that terebrids have adapted to dietary changes that may have resulted from predator-prey relationships. The anatomical and phylogenetic results presented serve as a starting point to advance investigations about the role of predator-prey interactions in the diversification of the Terebridae and the impact on their peptide toxins, which are promising bioactive compounds for biomedical research and therapeutic drug development.

PPARα as a Transcriptional Regulator for Detoxification of Plant Diet-Derived Unfavorable Compounds

Plants contain potentially toxic compounds for animals and animals have developed physiological strategies to detoxify the ingested toxins during evolution. Feeding mice with various plant seeds and grains showed unexpected result that only sesame killed PPARα-null mice but not wild-type mice at all. A detailed analysis of this observation revealed that PPARα is involved in the metabolism of toxic compounds from plants as well as endobiotic substrates by inducing phase I and phase II detoxification enzymes. PPARα plays a vital role in direct or indirect activation of the relevant genes via the complex network among other xenobiotic nuclear receptors. Thus, PPARα plays its wider and more extensive role in energy metabolism from natural food intake to fat storage than previously thought.

Effect of graded doses of Caesalpinia bonducella seed extract on ovary and uterus in albino rats

Histological changes observed under light microscope illustrate follicular degeneration in ovary, vacuolation and mild disorganization of uterus on treatment with graded doses of alcohol seed extract of Caesalpinia bonducella. There was a significant decrease (p≤0.05) in duration of estrous cycle and mean ovarian weight. However, there were no uniform variations in mean uterine weight, serum estradiol and progesterone level. The results suggest that alcohol seed extract of C. bonducella has antiestrogenic property, possibly acting via inhibition of estrogen secretion.

Physiologic roles of hepatic lipid droplets and involvement of peroxisome proliferator-activated receptor alpha in their dynamism

The liver is not a storage site of excess energy as triacylglycerides but a major site of carbohydrate storage, playing a vital role in glucose homeostasis, and the hepatic lipid droplets (LDs) should have a distinct physiologic role from those in lipid-storing tissues. Most studies so far have been limited to characterization of the LDs in cultured cells or of the liver of animals maintained on a normal laboratory diet, and little is known about the properties of the LDs in the liver responding to dietary excess, irregular fats, and potentially toxic compounds contained in a natural food diet. We started to characterize the hepatic LDs in wild-type and peroxisome proliferator-activated receptor alpha (PPARalpha)-null mice fed various natural diets by identifying the liver-enriched LD-associated proteins and the changes in lipid compositions. Based on the currently available data, we propose the hypothesis that hepatic LDs play vital protective roles against diet-derived excess fatty acids and potentially toxic hydrophobic compounds by temporarily storing them as neutral lipids or compounds until completion of the remodeling of fatty acids and detoxification of the compounds in a PPARalpha-dependent manner.

Small mammals collected from a site with elevated selenium concentrations and three reference sites

Small mammals were trapped in July, August, and September 1999 at Kesterson Reservoir (Merced County, CA), a site with elevated concentrations of selenium (Se), and at three nearby reference sites. Deer mice (Peromyscus maniculatus) were the most frequently trapped species at all of the sites, and western harvest mice (Reithrodontomys megalotis) and house mice (Mus musculus) were also trapped frequently. About half the animals collected from the reference sites were in reproductive condition, compared to less than a quarter of the animals from Kesterson. A lower proportion of the deer mice trapped at Kesterson was male, compared to about half at the reference sites. Deer mice from Kesterson also tended to have a lower condition index (body weight/body length) than those from the reference sites. Mice from Kesterson had enlarged livers, based on a higher liver-to-body-weight ratio (% liver). Male mice from Kesterson tended to have a smaller anogenital distance than male mice from reference sites, suggesting some feminization of Kesterson mice. Mice from Kesterson had higher liver Se concentrations than mice from reference sites, and some mice from reference sites had surprisingly low liver Se concentrations. It is possible that the effects observed were caused by physical stressors at Kesterson such as lower water and food availability but it also suggests that long-term exposure to elevated levels of Se may be, in part, the cause of some of the differences observed in small mammals from Kesterson.

Sida carpinifolia (Malvaceae) poisoning in fallow deer (Dama dama)

A captive fallow deer (Dama dama) in a zoo was spontaneously poisoned after consumption of Sida carpinifolia. The paddock where cervids were kept was severely infested by S. carpinifolia. The deer developed a neurological syndrome characterized by muscular weakness, intention tremors, visual and standing-up deficits, falls, and abnormal behavior and posture. Because a severe mandibular fracture and the consequent deteriorating condition, it was euthanized. Main microscopic findings were swelling and multifocal cytoplasmic vacuolation in the Purkinje cells. The cytoplasm of multiple cells of the cerebellum, especially the Purkinje cells, stained with the lectins Concanavalia ensiformis, Triticum vulgaris, and succinylated Triticum vulgaris. Diagnostic possibilities such as bovine diarrhea virus, rabies, and transmissible spongiform encephalopathy were excluded. The report focuses on the risk of maintaining S. carpinifolia populations in zoo enclosures of wild herbivores.

Comparison between phytoestrogens and estradiol in the preventionof atheroma in ovariectomized cholesterol-fed rabbits

OBJECTIVES

There is increasing interest in the role of complementary and alternative medicines for the treatment of menopause-related problems. This study compared the preventive effect on atheroma formation of a commercially available mixed phytoestrogen concentrate with that of estradiol.

METHODS

An ovariectomized cholesterol-fed rabbit model of atheroma formation was used. Rabbits were ovariectomized before the commencement of the 12-week treatment period. There were two control groups. Control Group 1 received isoflavone-free rabbit chow whilst Control Group 2 received 1% cholesterol-enriched isoflavone-free rabbit chow. Rabbits in Group 3 received 1% cholesterol-enriched isoflavone-free rabbit chow plus a 500 mg tablet containing a concentrated extract of Trifolium pretense (red clover). Rabbits in Group 4 received 1% cholesterol-enriched isoflavone-free rabbit chow plus a 0.5 mg tablet of oral estradiol. Atheroma formation was measured by, first, calculation of the area of atheroma on the intimal surface, and, second, measuring the cholesterol content in the aorta.

RESULTS

There were no significant differences in serum cholesterol between the cholesterol-fed control Group 2 and the treatment Groups 3 and 4. However, there was significantly less staining for atheroma and significantly less cholesterol accumulation in the aorta in Group 4 (estradiol-treated) rabbits compared with either control Group 2 or Group 3 (phytoestrogen-treated) rabbits.

CONCLUSION

In this study, only estradiol was shown to have a significant protective effect against atheroma formation.

Quantitative variability of cyanogenesis in Cathariostachys madagascariensis-the main food plant of bamboo lemurs in Southeastern Madagascar

Giant bamboo (Cathariostachys madagascariensis) is a major food plant for three sympatric species of bamboo-eating lemurs (Hapalemur aureus, H. griseus, and Prolemur simus) in the rain forests of southeastern Madagascar. This plant species is strongly cyanogenic. However, quantitative data on cyanide concentration in C. madagascariensis are scarce. Previous studies reported 15 mg cyanide per 100 g fresh shoot material (corresponding to approx. 57 micromol cyanide per gram dry weight). However, we found mean concentrations (+/-SE) ranging from 139.3+/-19.32 in ground shoots to 217.7+/-16.80 micromol cyanide per gram dry weight in branch shoots. Thus, cyanogenesis of C. madagascariensis was up to four times higher than reported before. In contrast to the strongly cyanogenic shoots no cyanide could be detected in differently aged leaves of C. madagascariensis confirming earlier studies. Within individual shoots fine-scaled analysis revealed a characteristic ontogenetic pattern of cyanide accumulation. Highest concentrations were found in youngest parts near the apical meristem, whereas concentrations decreased in older shoot parts. Beyond the general intra-individual variability of cyanogenic features analyses indicated site-specific variability of both, the ontogenetic pattern of cyanide concentration as well as the total amount of cyanide accumulated in shoots. Additionally, analyses of soluble proteins-one important nutritive measure affecting food plant quality-demonstrated a converse quantitative relation of protein concentrations in leaves to cyanide concentration in shoots at the site-specific level. We, thus, suggest integrative analyses on quantitative variation of cyanogenesis together with nutritive plant parameters in future studies. This approach would allow obtaining more detailed insights into spatial variability of giant bamboo's overall browse quality and its impact on lemur herbivores.

Influence of dietary feeding of low monomer content grape seed extract on vitellogenin production and cholesterol levels in goldfish, Carassius auratus

Grape seed extract (GSE) is a source of naturally occurring compounds known as proanthocyanidins and flavan-3-ols, which are recognized to exert a protective effect on human health, so GSE is widely used mainly as a nutritional supplement. However, polyphenols may have, in some cases, estrogenic effects or may interfere with the endocrine system. For that reason, it was considered of interest to investigate the beneficial or detrimental effects induced by low monomer content grape seed extract (LMC-GSE) in a teleost experimental model, the juvenile goldfish (Carassius auratus); therefore, biomarkers of estrogenic exposure together with cholesterol titers were assessed in both plasma and tissue samples taken from fish fed with different doses of LMC-GSE for 4 weeks. Dietary LMC-GSE (71 or 35 mg/g diet) did not affect vitellogenin (VTG) synthesis; on the contrary, VTG production was exclusively induced in fish fed with an estradiol-17beta (E2)-incorporated diet. In addition, it was found that both plasma E2 levels and hepatic total cholesterol were not affected by LMC-GSE dietary regimens.

How do predators cope with chemically defended foods?

Many prey species (including plants) deter predators with defensive chemicals. These defensive chemicals act by rendering the prey's tissues noxious, toxic, or both. Here, I explore how predators cope with the presence of these chemicals in their diet. First, I describe the chemosensory mechanisms by which predators (including herbivores) detect defensive chemicals. Second, I review the mechanisms by which predators either avoid or tolerate defensive chemicals in prey. Third, I examine how effectively free-ranging predators can overcome the chemical defenses of prey. The available evidence indicates that predators have mixed success overcoming these defenses. This conclusion is based on reports of free-ranging predators rejecting unpalatable but harmless prey, or voluntarily ingesting toxic prey.

Dual subcellular localization in the endoplasmic reticulum and peroxisomes and a vital role in protecting against oxidative stress of fatty aldehyde dehydrogenase are achieved by alternative splicing

Fatty aldehyde dehydrogenase (FALDH, ALDH3A2) is thought to be involved in the degradation of phytanic acid, a saturated branched chain fatty acid derived from chlorophyll. However, the identity, subcellular distribution, and physiological roles of FALDH are unclear because several variants produced by alternative splicing are present in varying amounts at different subcellular locations. Subcellular fractionation experiments do not provide a clear-cut conclusion because of the incomplete separation of organelles. We established human cell lines heterologously expressing mouse FALDH from each cDNA without tagging under the control of an inducible promoter and detected the variant FALDH proteins using a mouse FALDH-specific antibody. One variant, FALDH-V, was exclusively detected in peroxisomal membranes. Human FALDH-V with an amino-terminal Myc sequence also localized to peroxisomes. The most dominant form, FALDH-N, and other variants examined, however, were distributed in the endoplasmic reticulum. A gas chromatography-mass spectrometry-based analysis of metabolites in FALDH-expressing cells incubated with phytol or phytanic acid showed that FALDH-V, not FALDH-N, is the key aldehyde dehydrogenase in the degradation pathway and that it protects peroxisomes from oxidative stress. In contrast, both FALDHs had a protective effect against oxidative stress induced by a model aldehyde for lipid peroxidation, dodecanal. These results suggest that FALDH variants are produced by alternative splicing and share an important role in protecting against oxidative stress in an organelle-specific manner.

Soy isoflavones improve spatial delayed matching-to-place performance and reduce cholinergic neuron loss in elderly male rats

To investigate the protective activity of soy isoflavones on neurons, the effects of isoflavones on cholinergic enzyme activity, immunoreactivities of cholinergic enzyme, and delayed matching-to-place (DMP) performance were measured in normal elderly rats. Male Sprague-Dawley rats (n = 48; 10 mo old) were assigned to 3 groups: CD (control diet), ISO 0.3 (0.3 g/kg soy isoflavones diet), and ISO 1.2 (1.2 g/kg soy isoflavones diet). After 16 wk of consuming these diets, choline acetyltransferase (ChAT) activity in the ISO 0.3 group was greater in cortex and basal forebrain (BF; P < 0.05) than in controls. In BF, ChAT activity was also significantly greater in the ISO 1.2 group than in control rats. Acetylcholine esterase (AChE) activity in the ISO 0.3 group was significantly inhibited in cortex, BF, and hippocampus and in the ISO 1.2 group in cortex and hippocampus. Choline acetyltransferase immunoreactivity (ChAT-IR) in the ISO 1.2 group was significantly greater than in controls in the medial septum area. ChAT-IR in the ISO 0.3 and ISO 1.2 groups was significantly higher than in the CD group in the hippocampus CA1 area. Spatial DMP performance by the ISO 0.3 group showed significantly shorter swimming time than by the CD group. These findings show that soy isoflavones can influence the brain cholinergic system and reduce age-related neuron loss and cognition decline in male rats.

Signal transduction through the Ras/Erk pathway is essential for the mycoestrogen zearalenone-induced cell-cycle progression in MCF-7 cells

Zearalenone is a naturally occurring estrogenic contaminant of moldy feeds and is present in high concentrations in dairy products and cereals. Zearalenone was postulated to contribute to the overall estrogen load of women, but the mechanisms of its action are not known. We demonstrated that zearalenone could stimulate the growth of estrogen receptor-positive human breast carcinoma cell line MCF-7. In addition, zearalenone functioned as an antiapoptotic agent by increasing the survival of MCF-7 cell cultures undergoing apoptosis caused by serum withdrawal. Treatment of these cells with 100 nM zearalenone induced cell-cycle transit after increases in the expression of c-myc mRNA and cyclins D1, A, and B1 and downregulation of p27(Kip-1). G(1)/G(2)-phase kinase activity and phosphorylation of the retinoblastoma gene product was also evident. Flow cytometric analysis demonstrated entry of cells into the S and G(2)/M phases of the cell cycle, and phosphorylation of histone H3 occurred 36 h after zearalenone treatment. Ectopic expression of a dominant-negative p21(ras) completely abolished the zearalenone-induced DNA synthesis in these cells, and the specific inhibitor PD98059 for mitogen/extracellular-regulated protein kinase kinase arrested S-phase entry induced by zearalenone. These data suggest that the mitogen-activated protein kinase signaling cascade is required for zearalenone's effects on cell-cycle progression in MCF-7 cells. Given the presence of this mycotoxin in cereals, milk, and meat, the possibility that zearalenone is a potential promoter of breast cancer tumorigenesis should be investigated further. Mol. Carcinog. 30:88-98, 2001.

Soy based diet attenuates the development of hypertension when compared to casein based diet in spontaneously hypertensive rat

The purpose of this study was to compare the effects of soy and casein based diets on blood pressure and cardiovascular functions in male and female spontaneously hypertensive rats (SHR). The systolic blood pressure was measured at the beginning and at the end of study. After a five week supplementation period with three different diets, the rats were decapitated and arterial responses and the weight-to-body weight-ratios of the organs were studied. The development of hypertension was attenuated in both female and male rats on soy protein diet when compared to the casein diet. Soy based diet lowered serum total cholesterol level when compared to the control diet. Both casein and soy protein supplementation in diet induced a significant renal hypertrophy in both female and male SHR rats when compared to SHR rats on the control diet. Soy protein supplementation reduced significantly serum estradiol-17beta concentration when compared to the control diet. There were no differences in the serum testosterone concentrations between the diet groups. When compared to the casein based diet the soy based diet attenuated the development of hypertension and decreased serum total cholesterol level in SHRs. These effects were independent of gender. The mechanisms and clinical importance of these findings remain to be clarified.

Sex differences in feeding-patch choice in a megaherbivore: elephants in Chobe National Park, Botswana

Differences in diet and patch choices of African elephants (Loxodonta africana) according to sex and herd structure were examined during the dry season in a dystrophic savanna-woodland ecosystem in northern Botswana. The study revealed that female elephants with dependent young fed more selectively than the very large adult males, as indicated by the large number of woody plant species utilised, in order to minimise fibre intake, at both the woody plant species level and the feeding-patch level. Adult females fed on more woody plant species per unit area in patches containing higher numbers of such plants than adult males. Family units also browsed on more woody plant species per unit area and in total than adult males. Finally, family units discriminated between patches in their surroundings and selected patches offering the highest density of palatable species, whereas males were apparently ignorant of the distribution of resources in their environment and browsed in patches containing the same amount and combination of species as surrounding areas. This suggests that body size is a paramount factor mediating dietary differences between the sexes in African elephants at both the feeding-patch and the woody plant species level. These findings are consistent with the sexual dimorphism - body size hypothesis, which states that an increase in body size leads to a relaxation of the requirement for selectivity in feeding.

Phytoestrogens: dietary intake and excretion in postmenopausal Chinese women

OBJECTIVES

The aims of this study were to estimate the dietary intake of phytoestrogens and to measure urinary phytoestrogen excretion in postmenopausal Chinese women.

METHODS

Postmenopausal Chinese women were recruited from the hormone replacement clinic of the Prince of Wales Hospital. Dietary intake of phytoestrogen-rich foods was estimated using a food frequency questionnaire. Urinary output of the isoflavonoids daidzein and genistein and the metabolite of daidzein, equol, was measured using high-performance liquid chromatography.

RESULTS

The mean daily excretion of daidzein, genistein and equol was 3.24 (+/- 3.63), 1.47 (+/- 1.75) and 0.64 (+/- 1.53) mumol, respectively. The total mean daily isoflavonoid excretion was 5.36 (+/- 5.27) mumol.

CONCLUSIONS

Urinary excretion of isoflavonoid phytoestrogens in this Chinese population was lower than that reported in Japanese subjects. This may be due to the higher consumption of legumes, especially soy products, in the Japanese compared to the Chinese diet. The intake of green vegetables was higher in the Chinese subjects, and this food group may be the main contributor to their total phytoestrogen intake.

Phytoestrogens--a short review

The wide distribution of plant estrogens or 'phytoestrogens' in cereals, vegetables and medicinal plants raises questions concerning the possible health risks and benefits associated with their consumption. In this article, we provide a synopsis of the literature relating principally to the clinical effects of phytoestrogens on the diseases associated with ageing. The sources, metabolism and properties of the different phytoestrogens are also discussed. The studies included were primarily restricted to those with data pertinent to clinical practice. Our contention is that phytoestrogens are at least part of the reason why vegetarians and Asian populations have a low rate of cancer and heart disease.

Is the bitter rejection response always adaptive?

The bitter rejection response consists of a suite of withdrawal reflexes and negative affective responses. It is generally assumed to have evolved as a way to facilitate avoidance of foods that are poisonous because they usually taste bitter to humans. Using previously published studies, the present paper examines the relationship between bitterness and toxicity in mammals, and then assesses the ecological costs and benefits of the bitter rejection response in carnivorous, omnivorous, and herbivorous (grazing and browsing) mammals. If the bitter rejection response accurately predicts the potential toxicity of foods, then one would expect the threshold for the response to be lower for highly toxic compounds than for nontoxic compounds. The data revealed no such relationship. Bitter taste thresholds varied independently of toxicity thresholds, indicating that the bitter rejection response is just as likely to be elicited by a harmless bitter food as it is by a harmful one. Thus, it is not necessarily in an animal's best interest to have an extremely high or low bitter threshold. Based on this observation, it was hypothesized that the adaptiveness of the bitter rejection response depends upon the relative occurrence of bitter and potentially toxic compounds in an animal's diet. Animals with a relatively high occurrence of bitter and potentially toxic compounds in their diet (e.g., browsing herbivores) were predicted to have evolved a high bitter taste threshold and tolerance to dietary poisons. Such an adaptation would be necessary because a browser cannot "afford" to reject all foods that are bitter and potentially toxic without unduly restricting its dietary options. At the other extreme, animals that rarely encounter bitter and potentially toxic compounds in their diet (e.g., carnivores) were predicted to have evolved a low bitter threshold. Carnivores could "afford" to utilize such a stringent rejection mechanism because foods containing bitter and potentially toxic compounds constitute a small portion of their diet. Since the low bitter threshold would reduce substantially the risk of ingesting anything poisonous, carnivores were also expected to have a relatively low tolerance to dietary poisons. This hypothesis was supported by a comparison involving 30 mammal species, in which a suggestive relationship was found between quinine hydrochloride sensitivity and trophic group, with carnivores > omnivores > grazers > browsers. Further support for the hypothesis was provided by a comparison across browsers and grazers in terms of the production of tannin-binding salivary proteins, which probably represent an adaptation for reducing the bitterness and astringency of tannins.(ABSTRACT TRUNCATED AT 400 WORDS)