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.     

In vitro study of lipid metabolism in the mealworm larval fat body

Lipid metabolism in Tenebrio larval fat body has been studied in vitro. Lipid release required the presence of diluted hemolymph in the incubation medium. This time-dependent release of lipid was strongly stimulated in a dose-dependent manner by Tenebrio corpora cardiaca (CC) extracts or synthetic adipokinetic hormone (AKH I). Furthermore, some glycerol was released when larval fat body was incubated without hemolymph, and this phenomenon was also dose dependent for added CC extracts. Lipid synthesis was estimated in vitro by following the incorporation of radioactivity from [6-¹⁴C] glucose into fatty acids. Lipogenesis occurred in the absence of added carbohydrates in the medium, but it was stimulated by the addition of glucose, and especially trehalose (10 mg ml^?1). Intestinal insulin-like peptide (ILP) also stimulated in vitro lipogenesis in a dose-dependent fashion. We conclude that lipolytic and lipogenetic activities of larval mealworm fat body in vitro are effectively under hormonal control.     

The plasma membrane of epididymal epithelial cells has a specific receptor which binds to androgen-binding protein and sex steroid-binding protein.

The binding of [3H] delta 6-testosterone photoaffinity-labelled rat androgen-binding protein (rABP) has been studied in an enriched fraction of plasma membranes of epithelial epididymal cells in immature (15 days) and adult rats (40 days). The binding was maximal in less than 30 min and more rapid at 4 degrees C than at 34 degrees C. It was calcium and pH dependent. Scatchard plots of the binding data gave curvilinear plots with two types of binding sites corresponding to a K(ass1) of 18.2 nM-1 and K(ass2) of 1.6 nM-1 (2.2 x 10(11) sites/mg protein and 5.4 x 10(11) sites/mg protein, respectively). In adult rats, only one type of binding site was found, with a K(ass) of 3.7 nM-1 (4.5 x 10(11) sites/mg protein). The number of receptors was 5-fold lower in the cauda than in the caput of the epididymis. The pretreatment of the isolated intact cells with streptozotocin induced a 45% reduction of the binding. Only unlabelled rABP and hSBP (human sex steroid-binding protein) but not other proteins (lactotransferrin, serotransferrin, asialofetuine, fetuine and bovine serum albumin) competed with the labelled ligand to bind plasma membranes. The membrane fraction was solubilized by triton X-100. Its incubation with labelled rABP and hSBP provoked the elution of the tracer as an aggregate into the void volume fraction of superose 6B mini-gel filtration columns. Structural homology between hSBP and rABP could be responsible for the common behaviour of the steroid-carrier molecules for the ABP receptor of rat epididymal epithelial cells.     

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     

Differents aspects du fer dans l'organisme : II. Différentes formes de l'hémosidérine

On voit des molécules de ferritine apparaitre dans le cytoplasme des cellules réticulaires au cours de la digestion des érythrocytes, autour des stromas phagocytés. Cette ferritine s'accumule en amas dans lesquels entrent d'autres substances, en particulier des lipides, provenant aussi des stromas globulaires et qui apparaissent sous forme myélinique. Souvent la ferritine se dispose d'une manière cristalline. Parfois la ferritine et l'apoferritine alternent dans ces cristaux. Parfois l'hémosidérine contient des cristaux qui semblent bien être de l'apoferritine pure. L'injection de sels de fer donne lieu à l'apparition de ferritine dans les cellules réticulaires. Dans les conditions de nos expériences, la plus grande partie du fer injecté était sous forme de ferritine dans un délai de 3 jours. Un aspect intermédiaire entre celui du fer injecté et celui de la ferritine a été trouvé. Dans le cas des injections de saccharate de fer ce sont de fines aiguilles; dans le cas des injections de lactate de fer, il s'agit de masses fibreuses.     

Transcobalamin II--cobalamin binding sites are present on rabbit germ cells.

Specific binding sites for rabbit transcobalamin II have been found on isolated adult rabbit germ cells. Scatchard analysis revealed a single class of binding sites for [57Co]cyanocobalamin-transcobalamin II with an association constant (Ka) of 1.3 x 10(10) M-1 and 700 sites per cell. Binding was reversible, saturable and calcium dependent. Electron microscope radioautography following incubation with iodinated transcobalamin II at 4 degrees C led to a detectable labeling mainly restricted to the plasma membrane.     

Interspecific interference between Apoanagyrus lopezi and A. diversicornis, parasitoids of the cassava mealybug Phenacoccus manihoti

The parasitoids Apoanagyrus lopezi De Santis and A. diversicornis (Howard) (Hymenoptera: Encyrtidae) have been introduced into Africa for the biological control of the cassava mealybug Phenacoccus manihoti Matile-Ferrero (Homoptera: Pseudococcidae). We have studied competition between these species to investigate if they can coexist. Here we report on the influence of the simultaneous presence of non-conspecific adult females on searching efficiency on patches. Wasps of either species foraged on discs of cassava leaf with mealybugs, while at the same time different numbers of non-conspecifics were also depleting the patch. Patch area per parasitoid and number of hosts available to each parasitoid were equal in all treatments.In both species, the presence of other foragers clearly affected several aspects of the parasitoids' behaviour. Patch residence time increased with the number of non-conspecifics in A. diversicornis. In both parasitoid species, the proportion of hosts left unparasitized after the patch visit decreased with increasing numbers of females on the patch. The proportions of super- and multiparasitism did not change with the number of females. Both species produced more offspring during a patch visit in the presence of more non-conspecifics. These behavioural changes did not, however, lead to a change in the offspring production rate on patches. A. diversicornis produced offspring at a rate three times that of A. lopezi when one A. lopezi and one A. diversicornis foraged simultaneously. This is the first report of an aspect of interspecific competition where A. diversicornis has an advantage over A. lopezi. Interference between adult females thus promotes coexistence of the two species on P. manihoti.