Kentaro Q. Sakamoto

Can Ethograms Be Automatically Generated Using Body Acceleration Data from Free-Ranging Birds?

An ethogram is a catalogue of discrete behaviors typically employed by a species. Traditionally animal behavior has been recorded by observing study individuals directly. However, this approach is difficult, often impossible, in the case of behaviors which occur in remote areas and/or at great depth or altitude. The recent development of increasingly sophisticated, animal-borne data loggers, has started to overcome this problem. Accelerometers are particularly useful in this respect because they can record the dynamic motion of a body in e.g. flight, walking, or swimming. However, classifying behavior using body acceleration characteristics typically requires prior knowledge of the behavior of free-ranging animals. Here, we demonstrate an automated procedure to categorize behavior from body acceleration, together with the release of a user-friendly computer application, “Ethographer”. We evaluated its performance using longitudinal acceleration data collected from a foot-propelled diving seabird, the European shag, Phalacrocorax aristotelis. The time series data were converted into a spectrum by continuous wavelet transformation. Then, each second of the spectrum was categorized into one of 20 behavior groups by unsupervised cluster analysis, using k-means methods. The typical behaviors extracted were characterized by the periodicities of body acceleration. Each categorized behavior was assumed to correspond to when the bird was on land, in flight, on the sea surface, diving and so on. The behaviors classified by the procedures accorded well with those independently defined from depth profiles. Because our approach is performed by unsupervised computation of the data, it has the potential to detect previously unknown types of behavior and unknown sequences of some behaviors.

Corticosterone Predicts Foraging Behavior and Parental Care in Macaroni Penguins

Corticosterone has received considerable attention as the principal hormonal mediator of allostasis or physiological stress in wild animals. More recently, it has also been implicated in the regulation of parental care in breeding birds, particularly with respect to individual variation in foraging behavior and provisioning effort. There is also evidence that prolactin can work either inversely or additively with corticosterone to achieve this. Here we test the hypothesis that endogenous corticosterone plays a key physiological role in the control of foraging behavior and parental care, using a combination of exogenous corticosterone treatment, time-depth telemetry, and physiological sampling of female macaroni penguins (Eudyptes chrysolophus) during the brood-guard period of chick rearing, while simultaneously monitoring patterns of prolactin secretion. Plasma corticosterone levels were significantly higher in females given exogenous implants relative to those receiving sham implants. Increased corticosterone levels were associated with significantly higher levels of foraging and diving activity and greater mass gain in implanted females. Elevated plasma corticosterone was also associated with an apparent fitness benefit in the form of increased chick mass. Plasma prolactin levels did not correlate with corticosterone levels at any time, nor was prolactin correlated with any measure of foraging behavior or parental care. Our results provide support for the corticosterone-adaptation hypothesis, which predicts that higher corticosterone levels support increased foraging activity and parental effort.

The induction of cytochrome P450 1A1 by sudan dyes.

Azo dyes form a major class of chemically related compounds that are ubiquitous in foods, paints, printing inks, cosmetics, and also used as biological stains in histological and histopathological laboratories and clinics. Sudan I, sudan III, and sudan IV have been classified as category 3 carcinogens by International Agency for Research on Cancer. In this study, we investigated the difference between these three sudan dyes in induction of CYP1A1. We intraperitoneally treated Wistar rats with each of the three sudan dyes (I, III, and IV) for 3 days. Treatment of Wistar rats with sudan I produced the highest induction of CYP1A1 protein and mRNA whereas treatment of Wistar rats with sudan III produced about two third of CYP1A1 protein and mRNA than induced by sudan I. Furthermore, treatment of Wistar rats with sudan IV produced the lowest induction of CYP1A1 protein and mRNA which is about two third of that induced with sudan III treatment. We further investigated the effect of these sudan dyes on CYP1A1 transcription through investigating the xenobiotic response element (XRE) reporter activity in HepG2. The XRE reporter activity study showed the same trend of activity of sudan dyes comparable to the effects on CYP1A1 mRNA and protein. Immunohistochemical study revealed a differential pattern of distribution of CYP1A1 protein in rat liver among the three sudan dyes, apparent in the centrilobular and midzonal region with sudan III, progressing to panlobular with sudan I, whereas sudan IV showed a reversal of pattern of induction with the most intense staining in the periportal region. Our results suggest that there is an inverse relationship between the molecular size of the three sudan dyes and their ability to induce CYP1A1.

Elevated Warfarin Metabolism in Warfarin-Resistant Roof Rats (Rattus rattus) in Tokyo

Wild roof rats (Rattus rattus) live in proximity to human habitats, and they may carry numerous pathogens of infectious diseases. Pest control is important for public health, and warfarin is a commonly used rodenticide worldwide. However, continual use of warfarin may cause drug resistance in rodents and lead to failure of their control, especially in urbanized areas. In warfarin-resistant rats, the warfarin level in plasma was significantly lower after oral administration than that in the control warfarin-sensitive rats. Warfarin is metabolized by cytochrome P450 (P450), and hydroxylation of warfarin by P450 isoforms was significantly higher in warfarin-resistant rats (2-fold). Western blot analysis indicated that the level of CYP3A2 expression in warfarin-resistant rats was significantly larger than in warfarin-sensitive rats. The NADPH-P450 reductase activities in resistant rats were 8-fold higher than those in sensitive rats. In vivo, the administration of the P450 potent inhibitor proadifen (SKF-525A) increased the mortality of warfarin in the warfarin-resistant roof rats. We concluded that the mechanism of warfarin resistance in Tokyo roof rats is caused by increased clearance of warfarin.

Scaling of Soaring Seabirds and Implications for Flight Abilities of Giant Pterosaurs

The flight ability of animals is restricted by the scaling effects imposed by physical and physiological factors. In comparisons of the power available from muscle and the mechanical power required to fly, it is predicted that the margin between the powers should decrease with body size and that flying animals have a maximum body size. However, predicting the absolute value of this upper limit has proven difficult because wing morphology and flight styles varies among species. Albatrosses and petrels have long, narrow, aerodynamically efficient wings and are considered soaring birds. Here, using animal-borne accelerometers, we show that soaring seabirds have two modes of flapping frequencies under natural conditions: vigorous flapping during takeoff and sporadic flapping during cruising flight. In these species, high and low flapping frequencies were found to scale with body mass (mass −0.30 and mass −0.18) in a manner similar to the predictions from biomechanical flight models (mass −1/3 and mass −1/6). These scaling relationships predicted that the maximum limits on the body size of soaring animals are a body mass of 41 kg and a wingspan of 5.1 m. Albatross-like animals larger than the limit will not be able to flap fast enough to stay aloft under unfavourable wind conditions. Our result therefore casts doubt on the flying ability of large, extinct pterosaurs. The largest extant soarer, the wandering albatross, weighs about 12 kg, which might be a pragmatic limit to maintain a safety margin for sustainable flight and to survive in a variable environment.

A comparative study of cellulase and hemicellulase activities of brackish water clam Corbicula japonica with those of other marine Veneroida bivalves

SUMMARY Corbicula japonica is a typical brackish water bivalve species belonging to the order Veneroida, and it is the most important inland fishery resource in Japan. Corbicula japonica has been suggested to assimilate organic matter from terrestrial plants, unlike Ruditapes philippinarum and Mactra veneriformis, which selectively assimilate organic matter of marine origin. This led us to hypothesize that C. japonica, despite being a suspension feeder, could assimilate cellulosic materials derived from terrestrial plants. In the present study, we measured cellulase and hemicellulase activities in the crystalline styles of C. japonica and other commercially important Veneroida bivalve species in Japan: Ruditapes philippinarum, Meretrix lamarckii and Meretrix lusoria. Corbicula japonica demonstrated notably higher cellulase, xylanase and β-mannanase activities than the other marine bivalves, suggesting that this species possesses a far greater biochemical capacity to break down the structural polysaccharides of plant cell walls than the other species. In contrast, the β-1,3-glucanase and pectinase activities of C. japonica were similar to or even lower than those of the others. This is possibly due to the presence of these polysaccharides in the cell walls of diatoms, a principal food of most marine bivalves. Although direct evidence is lacking, the high cellulase, xylanase and β-mannanase activities of C. japonica may result from adaptation to an upstream estuarine environment where phytoplankton and diatoms are scarce, but plant-derived substances are abundant.

Crude cacao theobroma cacao extract reduces mutagenicity induced by benzo[a]pyrene through inhibition of CYP1A activity in vitro

Polyphenols have been shown to have potent antioxidant activity, and therefore, food containing polyphenols is expected to contribute to the prevention of cancer. However, food contains not only polyphenols but also various other constituents. We used the Ames test to investigate the effects of crude extracts of whole cacao products, which are known to be rich in polyphenols, on the mutagenicity of benzo[a]pyrene (B[a]P) in Salmonella typhimurium strain TA 98 and tert‐butyl hydroperoxide (t‐BuOOH) in S. typhimurium strain TA 102. B[a]P induces mutagenicity by metabolic activation and t‐BuOOH induces it by generation of free radicals. While white chocolate did not modulate the numbers of revertant colonies produced by B[a]P treatment, milk chocolate and cacao powder extracts did. On the other hand, surprisingly, none of the cacao products tested affected the number of revertant colonies when t‐BuOOH was used as the mutagen. At maximum concentration (13.25 mg cacao powder/ml), the crude cacao powder extract reduced ethoxyresorufin O‐deethylase activity to 17.4% of the control, suggesting that whole cacao products inhibit cytochrome P450 (CYP) 1A activity. In conclusion, inhibition of CYP1A activity by cacao products may prevent DNA damage by reducing metabolic activation of carcinogens. Copyright

Cytochrome P450 induction and gonadal status alteration in common carp (Cyprinus carpio) associated with the discharge of dioxin contaminated effluent to the Hikiji River, Kanagawa Prefecture, Japan

Accumulations of polychlorinated dibenzo-p-dioxins, dibenzofurans and coplanar polychlorinated biphenyls were analyzed in common carp (Cyprinus carpio) collected in the Hikiji River, Kanagawa Prefecture, Japan in which dioxin contaminated effluent was released during the period starting from November 1992 to March 2000. Higher levels of 2,3,7,8-tetrachlorinated dibenzo-p-dioxin toxic equivalents were observed in carps collected downstream to the dioxin release site (contaminated site) than the reference site. Modulations of cytochrome p450 (CYP) enzyme in liver, serum estrogen concentration and gonadal somatic index (GSI) were also measured as biomarkers for the contaminants. Total CYP content in livers was markedly higher in male and female carps from the contaminated site relative to the reference site fish. The expression level of the cytochrome p450 1A and Ethoxyresorufin O-deethylase activity were significantly higher in female carps from the contaminated site than from the reference site. A lower level of plasma estrogen was observed in carps from the contaminated site. The GSI in female carps from the contaminated site was smaller than that recorded at the reference site. The present study indicates that dioxins released to the Hikiji River might induce the CYP enzyme and inhibit the reproductive functions in common carps dwelling downstream from the release site.

A fundamental role for NO-PLC signaling pathway in mediating intracellular Ca2+ oscillation in pancreatic acini

The aim of the present study was to investigate the possible interaction between intracellular Ca(2+) and nitric oxide (NO) in rat pancreatic acinar cells, especially intracellular signaling events. (1) Nitric oxide donors SNP (0.1-100 μM) and NOR-3 (50-400 μM) induced Ca(2+) oscillations in fluo-4-loaded acini, that appeared to be analogous to what we usually observe in acini stimulated with physiological secretagogues such as CCK-8 and this oscillations were abolished in the presence of carboxy-PTIO. (2) The NO donors-evoked Ca(2+) oscillations were not abolished even in the absence of extracellular Ca(2+) but totally disappeared when cells were pretreated with thapsigargin, a sarcoplasmic-endoplasmic reticulum Ca(2+) ATPase (SERCA) inhibitor. (3) Inhibition of guanylate cyclase with 1 H-[1,2,4] oxadiazolo [4,3-a] quinoxaline-1-one (ODQ) attenuated Ca(2+) oscillations evoked by SNP in the absence of extracellular Ca(2+). (4) Inhibitors of phospholipase C activity, U73122 and the IP(3)R blocker xestospongin C, both abolished the SNP-induced Ca(2+) response. (5) Furthermore, we found that both CCK-8 and carbachol (CCh) induced NO production in DAF-2-loaded acinar cells and that an inhibitor of NO synthase, N(G)-monomethyl-l-arginine (L-NMMA), significantly reduced CCK-8-induced Ca(2+) oscillation. These results indicate that NO mobilizes Ca(2+) from internal stores through activation of guanylate cyclase and resultant cGMP production. In addition, PLC activation of IP(3) production is also suggested to be involved in Ca(2+) mobilization via IP(3) receptors. This suggests the presence of cross-talk between Ca(2+) and NO in pancreatic acini and this cascade may, at least partially, participate in physiological secretagogue-evoked Ca(2+) dynamics in pancreatic acinar cells.

Accelerometers Identify New Behaviors and Show Little Difference in the Activity Budgets of Lactating Northern Fur Seals (Callorhinus ursinus) between Breeding Islands and Foraging Habitats in the Eastern Bering Sea

We tagged 82 lactating northern fur seals (Callorhinus ursinus) with tri-axial accelerometers and magnetometers on two eastern Bering Sea islands (Bogoslof and St. Paul) with contrasting population trajectories. Using depth data, accelerometer data and spectral analysis we classified time spent diving (30%), resting (~7%), shaking and grooming their pelage (9%), swimming in the prone position (~10%) and two types of previously undocumented rolling behavior (29%), with the remaining time (~15%) unspecified. The reason for the extensive rolling behavior is not known. We ground-truthed the accelerometry signals for shaking and grooming and rolling behaviors—and identified the acceleration signal for porpoising—by filming tagged northern fur seals in captivity. Speeds from GPS interpolated data indicated that animals traveled fastest while in the prone position, suggesting that this behavior is indicative of destination-based swimming. Very little difference was found in the percentages of time spent in the categorical behaviors with respect to breeding islands (Bogoslof or St. Paul Island), forager type (cathemeral or nocturnal), and the region where the animals foraged (primarily on-shelf <200m, or off-shelf > 200m). The lack of significant differences between islands, regions and forager type may indicate that behaviors summarized over a trip are somewhat hardwired even though foraging trip length and when and where animals dive are known to vary with island, forager type and region.