Automated extraction of bank angles from bird‐borne video footage using open‐source software

The use of miniaturized video cameras to study the at‐sea behavior of flying seabirds has increased in recent years. These cameras allow researchers to record several behaviors that were not previously possible to observe. However, video recorders produce large amounts of data and videos can often be time‐consuming to analyze. We present a new technique using open‐source software to extract bank angles from bird‐borne video footage. Bank angle is a key facet of dynamic soaring, which allows albatrosses and petrels to efficiently search vast areas of ocean for food. Miniaturized video cameras were deployed on 28 Wandering Albatrosses (Diomedea exulans) on Marion Island (one of the two Prince Edward Islands) from 2016 to 2018. The OpenCV library for the Python programming language was used to extract the angle of the horizon relative to the bird’s body (= bank angle) from footage when the birds were flying using a series of steps focused on edge detection. The extracted angles were not significantly different from angles measured manually by three independent observers, thus being a valid method to measure bank angles. Image quality, high wind speeds, and sunlight all influenced the accuracy of angle estimates, but post‐processing eliminated most of these errors. Birds flew most often with cross‐winds (58%) and tailwinds (39%), resulting in skewed distributions of bank angles when birds turned into the wind more often. Higher wind speeds resulted in extreme bank angles (maximum observed was 94°). We present a novel method for measuring postural data from seabirds that can be used to describe the fine‐scale movements of the dynamic‐soaring cycle. Birds appeared to alter their bank angle in response to varying wind conditions to counter wind drift associated with the prevailing westerly winds in the Southern Ocean. These data, in combination with fine‐scale positional data, may lead to new insights into dynamic‐soaring flight.     

The uptake of liposome-entraped 125I-labelled poly(vinylpyrrolidone) by rat jejunum in vitro

The uptake of free and liposome-entrapped ¹²⁵I-labelled poly(vinylpyrrolidone) was measured in an intestinal sac preparation from adult rats. An an equal concentration of ¹²⁵I-labelled poly(vinylpyrrolidone), the rate of uptake of the liposome-entrapped material was four times that of the free macromolecule.     

The alpha-A-crystallin and cystathionine beta-synthase genes are physically very closely linked in proximal mouse chromosome 17

Murine genes homologous to those contributing to the Down syndrome (DS) phenotype in man are currently of interest because of their potential for providing animal models for the study of specific DS symptoms. Most of the genes mapping to human chromosome 21q22, where the DS genes are concentrated, are related to sequences located on mouse chromosome 16. Others, however, are known to map to mouse chromosome 10, and two genes, cystathionine beta-synthase (Cbs) and alpha-A-crystallin (Crya-1), have been localized to the proximal portion of mouse chromosome 17. In this paper, we show that the two genes mapping to human chromosome 21q22 and mouse chromosome 17 are very tightly linked in mouse, being separated by at least 70 kb, but not more than 130 kb. The very close physical linkage of mouse Cbs and Crya-1, combined with data that localize homologs of the closely flanking markers H2k and Pim-1 to human chromosome 6, suggests that the human 21q22/mouse chromosome 17 conserved segment is of a very limited total physical size and is likely to contain a relatively small number of genes.     

The effects of dietary (n-3) fatty acid supplementation on lipid dynamics and composition in rat lymphocytes and liver microsomes

Rats were fed diets devoid of (n-3) fatty acids (olive oil supplementation) or high in (n-3) fatty acids (fish oil supplementation) for a period of 10 days. In spleen lymphocytes and liver microsomes derived from animals fed fish oil diets, relatively high levels of (n-3) eicosapentaenoic (20:5), docosapentaenoic (22:5) and docosahexaenoic acids (22:6) were obtained compared to minimal levels when fed the olive oil diet. When the average lipid motional properties were examined by measuring the fluorescence anisotropy of diphenylhexatriene, no significant different was found between intact liver microsomes from animals fed the two diets. However, when lipid motion was examined in vesicles of phosphatidylcholine, isolated from the microsomes from fish oil fed animals (21.4% (n-3) fatty acids), the fluorescence anisotropy was significantly less than the corresponding phosphatidylcholine from olive oil fed animals (5.6% (n-3) fatty acids), indicating a more disordered or fluid bilayer in the presence of higher levels of (n-3) fatty acids. Phosphatidylethanolamine (n-3) fatty acids were also elevated after fish oil supplementation (41.3% of total fatty acids), compared to the level after olive oil supplementation (21.4%). The major effect of the fish oil supplementation was a replacement of (n-6) arachidonic acid by the (n-3) fatty acids and when this was 'modeled', using liposomes of synthetic lipids, 1-palmitoyl-2-arachidonyl(n-6) or docosahexaenoyl(n-3)-phosphatidylcholine, significant differences in lipid motional properties were found, with the docosahexaenoate conferring a more disordered or fluid lipid environment. Thus it appears that although lipid order/fluidity can be significantly decreased by increases in the highly unsaturated (n-3) fatty acid levels, alterations in membrane domain organization and/or phospholipid molecular species composition effectively compensated for the changes, at least as far as average lipid motional properties in the intact membranes was concerned.     

Production of pea lectin in Escherichia coli

In order to explore the molecular basis for the glycopeptide specificity of legume lectins, we have developed an experimental system in which specific amino acid alterations can be introduced into the carbohydrate binding site of pea lectin. This system is based on the production of pea lectin in Escherichia coli. The plasmid coding for the lectin was constructed from two lectin cDNA sequences isolated from Pisum sativum seeds (Higgins, T. J. V., Chandler, P. M., Zurawski, G., Button, S. C., and Spencer, D. (1983) J. Biol. Chem. 258, 9544-9549) and an expression vector based on the gene for the outer membrane lipoprotein of E. coli (Nakamura, K., and Inouye, M. (1982) EMBO J. 1, 771-775). The lectin is produced as a single polypeptide chain and forms insoluble aggregates in E. coli cells (2-5 mg/liter). Functional lectin is recovered by solubilization of the aggregates in guanidinium hydrochloride, renaturation in the presence of MnCl2 and CaCl2, and affinity purification on Sephadex. This procedure yields a homogeneous 28,000-dalton protein. Comparison of the recombinant lectin with natural pea lectin in an inhibition of hemagglutination assay demonstrated that there is no detectable difference in the carbohydrate binding properties of the two lectins.     

Protein Synthesis in Sonically Damaged Escherichia coli

By gentle sonic treatment, Escherichia coli cells were modified to permit penetration of actinomycin D, adenosine triphosphate, trypsin, ribonuclease, and polyuridylic acid. The behavior of these "soniplasts" as protein-synthesizing particles was investigated.     

Etude de la Faune submicroscopique de quelques tourbières à sphagnum

Sans résumé     

Human initial responses to immersion in cold water at three temperatures and after hyperventilation

The present investigation was designed to examine the influence of water temperature and prior hyperventilation on some of the potentially hazardous responses evoked by immersion in cold water. Eight naked subjects performed headout immersions of 2-min duration into stirred water at 5, 10, and 15 degrees C and at 10 degrees C after 1 min of voluntary hyperventilation. Analysis of the respiratory and cardiac data collected during consecutive 10-s periods showed that, at the 0.18-m/s rate of immersion employed, differences between the variables recorded on immersion in water at 5 and 10 degrees C were due to the duration of the responses evoked rather than their magnitude during the first 20 s. The exception to this was the tidal volume of subjects, which was higher on immersion in water at 15 degrees C than at 5 or 10 degrees C. The results suggested that the respiratory drive evoked during the first seconds of immersion was more closely reflected in the rate rather than the depth of breathing at this time. Hyperventilation before immersion in water at 10 degrees C did not attenuate the respiratory responses seen on immersion. It is concluded that, during the first critical seconds of immersion, the initial responses evoked by immersion in water at 10 degrees C can represent as great a threat as those in water at 5 degrees C; also, in water at 10 degrees C, the respiratory component of this threat is not influenced by the biochemical alterations associated with prior hyperventilation.