SignificanceIngesta leave characteristic wear features on the tooth surface, which enable us to reconstruct the diet of extant and fossil vertebrates. However, whether dental wear is caused by internal (phytoliths) or external (mineral dust) silicate abrasives is controversially debated in paleoanthropology and biology. To assess this, we fed guinea pigs plant forages of increasing silica content (lucerne < grass < bamboo) without any external abrasives, both in fresh and dried state. Abrasiveness and enamel surface wear increased with higher forage phytolith content. Additionally, water loss altered plant material properties. Dental wear of fresh grass feeding was similar to lucerne browsing, while dried grass caused more grazer-like wear. Fresh grass grazing could be confounded with browsing, being a major pitfall for paleodietary reconstructions.

The effect of phytoliths on tooth wear and function has been contested in studies of animal–plant interactions. For herbivores whose occlusal chewing surface consists of enamel ridges and dentine tissue, the phytoliths might particularly erode the softer dentine, exposing the enamel ridges to different occlusal forces and thus contributing to enamel wear. To test this hypothesis, we fed guinea pigs ( Cavia porcellus ; n = 36 in six groups) for three weeks exclusively on dry or fresh forage of low (lucerne), moderate (fresh timothy grass) or very high (bamboo leaves) silica content representing corresponding levels of phytoliths. We quantified the effect of these treatments with measurements from micro-computed tomography scans. Tooth height indicated extreme wear due to the bamboo diet that apparently brought maxillary incisors and molars close to the minimum required for functionality. There were negative relationships between a cheek tooth's height and the depth of its dentine basin, corroborating the hypothesis that dentine erosion plays an important role in herbivore tooth wear. In spite of lower body mass, bamboo-fed animals paradoxically had longer cheek tooth rows and larger occlusal surfaces. Because ever-growing teeth can only change in shape from the base upwards, this is a strong indication that failure to compensate for wear by dental height-growth additionally triggered general expansive growth of the tooth bases. The results suggest that enamel wear may intensify after enamel has been exposed due to a faster wear of the surrounding dentine tissue (and not the other way around), and illustrate a surprising plasticity in the reactivity of this rodent's system that adjusts tooth growth to wear.

Carnivore kill frequency is a fundamental part of predator–prey interactions, which are important shapers of ecosystems. Current field kill frequency data are rare and existing models are insufficiently adapted to carnivore functional groups. We developed a kill frequency model accounting for carnivore mass, prey mass, pack size, partial consumption of prey and carnivore gut capacity. Two main carnivore functional groups, small prey‐feeders versus large prey‐feeders, were established based on the relationship between stomach capacity (C) and pack corrected prey mass (iMprey). Although the majority of small prey‐feeders is below, and of large prey‐feeders above a body mass of 10–20 kg, both occur across the whole body size spectrum, indicating that the dichotomy is rather linked to body size‐related ecology than physiology. The model predicts a negative relationship between predator size and kill frequency for large prey‐feeders. However, for small prey‐feeders, this negative relationship was absent. When comparing carnivore prey requirements to estimated stomach capacity, small carnivores may have to eat to their full capacity repeatedly per day, requiring fast digestion and gut clearance. Large carnivores do not necessarily have to eat to full gastric capacity per day, or do not need to eat every day, which in turn reduces kill frequencies or drives other ecological processes such as scavenging, kleptoparasitism, and partial carcass consumption. Where ecological conditions allow, large prey‐feeding appears attractive for carnivores, which can thus reduce activities related to hunting. This is particularly so for large carnivores, who can achieve distinct reductions in hunting activity due to their relatively large gut capacity.

We herein describe a rational design of a heterogeneous catalyst composed of a dinuclear cuprate anion being immobilized electrostatically on one surface of Janus-type nanosheets while the other surface is decorated with highly hydrophobic octyl groups. The catalyst was found to be well dispersible in the organic phase of a biphasic aqueous/organic mixture. It was characterized by means of elemental analysis, atomic absorption spectroscopy, mass spectrometry, N2 absorption–desorption analysis, thermogravimetric analysis, scanning electron microscopy (SEM), and solid-state 13C and 29Si cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy. The Janus nature of the catalyst was investigated by employing a selective surface labeling method and by means of SEM. The catalyst shows higher activity compared to a non-Janus analogue in a biphasic synthesis. It was successfully used for the azide–alkyne cycloaddition and the Chan–Lam C–N coupling reaction. In addition, new and simple ways have been established for the production of a coumarin–triazole derivative and for the synthesis of the biologically active compound Monastrol via a solvent-free Biginelli reaction. The role of the dinuclear copper centers is discussed mechanistically.

Copper deficiency is a commonly diagnosed problem in cattle around the globe. In Jimma, Ethiopia, 8 zebu (Bos indicus) and 8 zebu × Holstein Friesian cross (Bos taurus × Bos indicus) heifers were used in an 11-wk study to investigate breed type differences and effects of Cu deficiency on concentrations of trace elements in plasma and edible tissues as well as mRNA expression of Cu-related genes. Heifers were fed a grass diet (6.4 ± 0.2 [SEM] mg Cu/kg DM) supplemented with 1 mg Mo/kg DM in wk 1 to 4 and 2 mg Mo/ kg DM in wk 5 to 11, with blood samples collected every 2 wk and tissue collection postmortem. Plasma, liver, kidney, and semitendinosus and cardiac muscle were analyzed for Zn, Cu, Fe, Se, Mo, Co, and Mn. Expression of mRNA Cu-related genes was measured in aorta (lysyl oxidase [LOX] ) as well as the Se-related glutathione peroxidase 1 (Gpx1). Zebu cattle maintained initial plasma Cu concentrations just below the threshold value for deficiency, whereas crossbred cattle gradually became severely Cu deficient over time (P < 0.001). In contrast, plasma Zn and Co were greater in zebu cattle at the onset of the trial but became similar to crossbred cattle towards the end of the trial (P < 0.001). Liver Cu (P = 0.002) and Fe (P 0.001), kidney Se (P < 0.001), and kidney and cardiac muscle Co (P 0.001) concentrations were greater in zebu than in crossbred cattle. Increased hepatic mRNA expression of the Cu regulatory genes Atp7b, Ctr1 (P = 0.02), CCS (P = 0.03), and Cox17 (P = 0.009) and Cu-related Sod1 (P = 0.001) as well as the Se-related Gpx1 (P 0.001) were greater in zebu than in crossbred cattle. However, duodenal mRNA expression of DAO (P = 0.8) and Mt1a (P = 0.2) and aortic expression of LOX (P = 0.8) were not different. Both the differences in Cu status indices (plasma and liver concentrations) and hepatic mRNA expression of Cu regulatory genes point to the possibility of a more efficient use of dietary Cu in B. indicus as compared to B. taurus × B. indicus cattle resulting in greater sensitivity to Cu deficiency in B. taurus crossbred cattle. initial plasma Cu concentrations just below the threshold value for deficiency, whereas crossbred cattle gradually became severely Cu deficient over time (P < 0.001). In contrast, plasma Zn and Co were greater in zebu cattle at the onset of the trial but became similar to crossbred cattle towards the end of the trial (P < 0.001). Liver Cu (P = 0.002) and Fe (P ≤ 0.001), kidney Se (P < 0.001), and kidney and cardiac muscle Co (P ≤ 0.001) concentrations were greater in zebu than in crossbred cattle. Increased hepatic mRNA expression of the Cu regulatory genes Atp7b, Ctr1 (P = 0.02), CCS (P = 0.03), and Cox17 (P = 0.009) and Cu-related Sod1 (P = 0.001) as well as the Se-related Gpx1 (P ≤ 0.001) were greater in zebu than in crossbred cattle. However, duodenal mRNA expression of DAO (P = 0.8) and Mt1a (P = 0.2) and aortic expression of LOX (P = 0.8) were not different. Both the differences in Cu status indices (plasma and liver concentrations) and hepatic mRNA ...

The effect of dietary particle size on gastrointestinal transit in carnivores has not been studied and might offer more insight into their digestive physiology. This study evaluated the effect of two dietary particle sizes (fine = 7.8 mm vs. coarse = 13 mm) of chunked day-old chicks on transit parameters in dogs. Six beagle dogs were fed both dietary treatments in a crossover design of 7 days with transit testing on the fifth day. Transit parameters were assessed using two markers, that is a wireless motility capsule (IntelliCap ) and titanium oxide (TiO ). Dietary particle size did not affect gastric emptying time (GRT), small bowel transit time (SBTT), colonic transit time (CTT) and total transit time (aTTT) of the capsule (p > .05). There was no effect of dietary particle size on TiO mean retention time (MRT) (p > .05). The time of last TiO excretion (MaxRT) differed (p = .013) between diets, being later for the coarse diet. Both MRT (R = 0.617, p = .032) and MaxRT (R = 0.814; p = .001) were positively correlated to aTTT. The ratio MRT/aTTT tended towards a difference between diets (p = .059) with the coarse diet exceeding fine diet values. Results show that the difference between capsule measurements and TiO is larger for the fine than the coarse diet suggesting that the capsule becomes more accurate when dietary particle size approaches marker size. Dietary particle size might have affected transit parameters but differences are too small to claim major physiological consequences.

No abstract

Pronounced variations in faecal consistency have been described anecdotally for some carnivore species fed a structure-rich diet. Typically two faecal consistencies are distinguished, namely hard and firm versus liquid and viscous faeces. It is possible that a separation mechanism is operating in the carnivore digestive tract, as in many herbivore species. Six beagle dogs were fed two experimental diets in a cross-over design of 7 days. Test diets consisted of chunked day old chicks differing only in particle size (fine = 7.8 mm vs coarse = 13 mm) in order to vary dietary structure. Digestive retention time was measured using titanium oxide (TiO2) as marker. The total faecal output was scored for consistency and faecal fermentation profiles were evaluated through faecal short-chain fatty acid (SCFA) and ammonia (NH3) analyses. A total of 181 faecal samples were collected. Dietary particle size did not affect faecal consistency, fermentative end products nor mean retention time (MRT). However, a faecal consistency dichotomy was observed with firm faeces (score 2–2.5) and soft faeces (score 4–4.5) being the most frequently occurring consistencies in an almost alternating pattern in every single dog. Firm and soft faeces differed distinctively in fermentative profiles. Although the structure difference between diets did not affect the faecal dichotomy, feeding whole prey provoked the occurrence of the latter which raises suspicion of a digestive separation mechanism in the canine digestive tract. Further faecal characterisation is however required in order to unravel the underlying mechanism.