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The Ecology of Parasitism
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
Anti-parasite behaviors can assume many forms. Birds often use their feet to scratch parts of the body they cannot reach with their beaks. Some birds have pectinate claws that look like the closely spaced teeth of a comb. Preening feathers with the beak is effective in removing parasites and is favored by having an overhang in the upper mandible. Experimental shortening of the overhang of the upper mandible of pigeons dramatically increases their loads of lice. Some birds like penguins engage in allopreening, cleaning the feathers of their mates in places like the head or neck that would otherwise be impossible to reach. Animals also engage in water or dust baths and whereas the former are unlikely to kill ectoparasites, the latter may affect ectoparasites by desiccation and abrasion.
The Objectives and Goals of Dermal Carcinogenicity Testing of Petroleum Liquids
Published in Rhoda G. M. Wang, James B. Knaak, Howard I. Maibach, Health Risk Assessment, 2017
James J. Freeman, Richard H. McKee
It is recommended that the dose volume be minimized as much as possible. Following application, the test material tends to spread to the interscapular region, and even relatively small dose volumes can spread onto the flanks and into the hair and skin folds in the axillary region. This was demonstrated in our laboratory using petroleum distillates ranging in viscosity from 4.1 cSt to 30 cSt at 40°C (these viscosities approximate that of fuel oil to crankcase oil). Dose volumes of 25 μl rapidly spread down the flanks and into the axillary region. This type of test material spread is of concern because entrapment in the skin folds in the axillary region may result in an increased level of irritation and associated scratching. More importantly, in dermal carcinogenesis bioassays it is sometimes questioned whether skin tumors which occasionally occur outside of the interscapular “treatment area” are treatment related. The potential spread of test material suggests that some may be. In addition, large volumes applied to the skin are of concern because of the possibility of ingestion via preening. The standard bioassay at Exxon utilizes a twice weekly dosing with 37.5 μl, which is sufficient to detect relatively weak (i.e., <10% of the mice develop tumors) skin carcinogens of petroleum origin (25 μl three times/week is equally effective).
Proteomes of the past: the pursuit of proteins in paleontology
Published in Expert Review of Proteomics, 2019
A single Siberian mammoth bone yielded 126 unique, partly intact protein types, detected by tandem mass spectrometry. This exemplifies many Cenozoic proteins including the ‘gold standard’ technique of sequencing [24]. This one discovery contains far more unique protein remnants than the total collection of biochemicals found in the entire Mesozoic so far sampled, illustrating both the potential abundance of original biochemistry in Cenozoic fossils, and the disappearance of that biochemistry due to degradation over time. Another more recent report describes the oldest original animal lipid. The pygidial (preening) gland from an extinct bird captured in Germany’s Messel Shale preserved still-yellow oil, now waxy [25]. Overall, the abundance of published protein sequences from recent fossil and subfossil specimens attests again to the general abundance of protein remnants in archeological and even some Cenozoic settings. Some of the same technologies used to reaffirm primary collagen in archeological bone may be applied to older bone samples.
Combining precision and power to maximize performance: a case study of the woodpecker’s neck
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
C. Böhmer, M. Furet, B. Fasquelle, P. Wenger, D. Chablat, C. Chevallereau, A. Abourachid
The neck in birds has been characterized as a highly complex system that positions the head during all kinds of behavior (Zweers et al. 1994; Böhmer et al. 2018). This involves a variety of highly demanding tasks such as feeding, manipulation, preening, sexual display, nest building, and combat behavior (Böhmer et al. 2019). This versatility is an opportunity for bioengineering, but prior to designing a technological model, the biological system must be understood; in particular regarding the form-function relationships. One behavioral pattern in birds that appears to be relatively constrained is pecking in woodpeckers. There is evidence that the drilling trajectory is essentially planar (Spring 1965). From a morphofunctional point of view, woodpeckers are highly interesting because they are very lightweight (mean body mass = 300 g), but are capable to dig into dense tree trunks (Puverel et al. 2019). They strike their beak against a tree repeatedly with high accelerations, high velocity and large force transmissions (May et al. 1979; Wang et al. 2011). We took this bird species as a first example for a biologically inspired robot arm that combines precision and power to maximize performance. Adding biological knowledge into the design process requires a simplification of the complexity of the biological entity (Whitesides 2015). In this context, we (1) analyzed the neck musculature which supplies force for movement; (2) established a planar robotic model using several stacked tensegrity crossed bar mechanisms and (3) integrated all data into an actuated model of the bird neck.