Melatonin is a highly conserved hormone in evolutionary history. It occurs in numerous organisms and plays a role in the endocrine and immune systems. Locomotor behavior is a basic behavior in ...animals and is an important indicator of circadian rhythms, which are coordinated by the nervous and endocrine systems. To date, the effect of melatonin on locomotor behavior has been studied in vertebrates, including syrian hamsters, sparrows, rats, zebrafish, goldfish, and flatworms. However, there have been few studies of the effects of melatonin on locomotor behavior in marine invertebrates. The goals of present study were to show the existence of melatonin in the sea cucumber
and to evaluate its effect on locomotor activity. In addition, muscle tissues from control and melatonin-treated sea cucumbers were tested using ultra performance liquid chromatography and quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) to determine the changes of metabolic activity in muscle. Melatonin was present in the coelomic fluid of
at a concentration of ∼135.0 ng/L. The total distance traveled and number steps taken over 9 h after melatonin administration decreased with increasing concentration of the melatonin dose. Mean and maximum velocity of movement and stride length and stride frequency also decreased, but their differences were not statistically significant. Overall, these results suggest that melatonin administration had a sedative effect on
. The levels of 22 different metabolites were altered in the muscle tissues of melatonin-treated sea cucumbers. Serotonin, 9-
retinoic acid, all-trans retinoic acid, flavin mononucleotide in muscles were downregulated after melatonin administration. Moreover, a high free fatty acid (FFA) concentration and a decrease in the adenosine 5'-triphosphate (ATP) concentration in the muscle tissues of the melatonin-treated group were detected as well. These results suggest that the sedative effect of melatonin involves some other metabolic pathways, and the reduced locomotor modulator-serotonin, inhibited fatty acid oxidation and disturbed oxidative phosphorylation are potential physiological mechanisms that result in the inhibitory effect of melatonin on locomotion in sea cucumbers.
The specific activity of aminoacyl-tRNA synthetases (spAARS), an index of growth rate, and of the electron transport system (spETS), an index of respiration, was measured in three size fractions ...(73-150 μm, >150 μm and >350 μm) of zooplankton during five cruises to tropical coastal waters of the Kimberley coast (North West Australia) and four cruises to waters of the Great Barrier Reef (GBR; North East Australia). The N-specific biomass of plankton was 3-4-fold higher in the Kimberley than on the GBR in all 3 size classes: Kimberley 1.27, 3.63, 1.94 mg m-3; GBR 0.36, 0.88 and 0.58 mg m-3 in the 73-150 μm, >150 μm and >350 μm size classes, respectively. Similarly, spAARS activity in the Kimberley was greater than that of the GBR: 88.4, 132.2, and 147.6 nmol PPi hr-1 mg protein -1 in the Kimberley compared with 71.7, 82.0 and 83.8 nmol PPi hr-1 mg protein -1 in the GBR, for the 73-150 μm, >150 μm and >350 μm size classes, respectively. Specific ETS activity showed similar differences in scale between the two coasts: 184.6, 148.8 and 92.2 μL O2 hr-1 mg protein-1 in the Kimberley, against 86.5, 88.3 and 71.3 μL O2 hr-1 mg protein-1 in the GBR. On the basis of these measurements, we calculated that >150 μm zooplankton grazing accounted for 7% of primary production in the Kimberley and 8% in GBR waters. Area-specific respiration by >73 μm zooplankton was 7-fold higher in the Kimberley than on the GBR and production by >150 μm zooplankton was of the order of 278 mg C m-2 d-1 in the Kimberley and 42 mg C m-2 d-1 on the GBR. We hypothesize that the much stronger physical forcing on the North West shelf is the principal driver of higher rates in the west than in the east of the continent.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Some of the most important demographic parameters underlying the resilience of coral communities are determined by their patterns of reproduction. In this study, a variety of methods were used to ...investigate the patterns of spawning, larval development and dispersal for scleractinian corals at an isolated reef system off northwestern Australia. Two distinct periods of gamete maturation and multi-specific spawning occurred each year, during Spring and Autumn, in contrast to the single season of mass spawning described on most other reefs around Australia. The subsequent rates of embryogenesis and larval development were among the fastest described for corals, with pre-competency periods of approximately 3 days. Within 3 days of spawning, slicks of spawn and current drifters had dispersed up to 5 km, and up to 10 km after 6 days, while the times taken for drifters to travel between adjacent (>240 km) reef systems were similar to or greater than the upper competency periods of most coral larvae. Thus, under these conditions, the entire reef system, and to some extent the reefs within the system, may largely be self-seeded; rates of immigration from other systems are probably insufficient to rapidly increase the recovery of communities within years of a major disturbance. These results have implications for the management of isolated reef systems, highlighting the need to minimize local stressors and maximize community resilience to the increasing scale of disturbance and habitat fragmentation.
Surface velocity observations from satellite tracked drifters made between 1987 and 2008 were used to resolve the surface circulation of the western Coral Sea, west of 158°E, and the Great Barrier ...Reef (GBR). The mean surface current map depicts well the major circulation patterns of the region, such as the position of the north Vanuatu and north Caledonia jets (NVJ and NCJ) and the western boundary currents. The North Queensland Current (NQC) and the East Australian Current (EAC) are well defined, flowing at speeds greater than 50 cm s−1 to the north, south of 15°S and 19°S, respectively. The NQC/EAC is mainly formed by the NVJ/NCJ flows, respectively. The presence of the Queensland Plateau greatly affects the westward flow, causing a zone of weak and highly variable currents that extends from 15°S to 18°S between the Queensland Plateau and the GBR shelf. Of the 235 drifters that crossed the western Coral Sea, 75 entered the GBR. Analysis of the drifter trajectories inside the GBR reveals the presence of a northwestward circulation at speeds of 22 cm s−1 north of 18°S and 0.5 cm s−1 south of 18°S. Drifter travel times used to evaluate the water residence times within the GBR indicate residence times of a few weeks for most of the lagoon.
The GDP concept has historically been used to measure human wellbeing and progress. This analytical purview is now coming into question. The GDP concept limits analysis to the economic factor and ...ignores the social and cultural. Analysis should focus on how well the people are doing. An avalanche of studies is now being directed toward dethroning the GDP as the sole indicator of human well-being and progress. This has been manifest in the derivation of many social indexes which indicate that while the global economy as well as the American economy are experiencing GDP growth, basic needs are not being fulfilled.
Recent research has examined the long-distance hiking community on the Appalachian Trail (AT) and attempted to understand members of this leisure subculture in terms of their sociality and social ...practices. Using Gelder's subcultural perspective, we continue this line of research by comparing hikers' interactions and experiences on the AT to a second well-known long-distance hiking trail, the Pacific Crest Trail (PCT). Analysis of ethnographic field notes and interviews with 72 long-distance hikers suggests that while there are unique experiences associated with each trail, there is a more general long-distance hiking subculture. More specifically, the long-distance hiking subcultures on the AT and PCT are nested or geographically situated subcultures within a larger hiking subculture. This article contributes to scholarship on place attachment, place identity, and leisure subcultures by further examining the long-distance hiking community as well as the role of specific recreational settings in the formation of leisure subcultures and subcultural identities.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, FSPLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Tropical marginal seas (TMSs) are natural subregions of tropical oceans containing biodiverse ecosystems with conspicuous, valued, and vulnerable biodiversity assets. They are focal points for global ...marine conservation because they occur in regions where human populations are rapidly expanding. Our review of 11 TMSs focuses on three key ecosystems-coral reefs and emergent atolls, deep benthic systems, and pelagic biomes-and synthesizes, illustrates, and contrasts knowledge of biodiversity, ecosystem function, interaction between adjacent habitats, and anthropogenic pressures. TMSs vary in the extent that they have been subject to human influence-from the nearly pristine Coral Sea to the heavily exploited South China and Caribbean Seas-but we predict that they will all be similarly complex to manage because most span multiple national jurisdictions. We conclude that developing a structured process to identify ecologically and biologically significant areas that uses a set of globally agreed criteria is a tractable first step toward effective multinational and transboundary ecosystem management of TMSs.
The shelf circulation off Ningaloo Reef near the North West Cape of Western Australia is driven by complex interactions between the southward flowing Leeuwin Current and wind‐driven currents that ...episodically reverse the coastal flow toward the north. The presence of these northward (equatorward) wind‐driven currents is thought to make this section of coast one of the few locations along Western Australia to experience periodic coastal upwelling. We used a combination of field observations and numerical modeling to investigate the summer circulation and upwelling dynamics along Ningaloo Reef. We analyzed current and temperature profiles from moorings at four sites across the shelf and used two Regional Ocean Modeling System (ROMS) sub‐models: (1) a coarser model of northwestern Australia forced by a global ocean model and (2) a nested fine‐scale model of the Ningaloo region. This nesting significantly improved model skill as it included the offshore mesoscale dynamics that strongly influenced the shelf circulation off Ningaloo. The field observations revealed several northward flow reversals, accompanied by cooling of the coastal waters adjacent to Ningaloo, which were associated with strong northward wind events. Analysis of the coastal heat budget revealed that cooling events were primarily driven by upwelling, whereas warming of coastal waters during relaxation events resulted mostly from along‐shelf advection of warm water from the north. Due to the combined effects of its relatively steep (~1/50 slope) shelf and strong summer stratification, upwelled water was sourced from the interior of the water column, likely influencing the sources and fluxes of nutrients to Ningaloo Reef.
Key Points
Coastal cooling dominated by upwelling; warming by alongshore advectionVertical structure of upwelling is strongly influenced by stratificationUpwelling depends on the balance between wind and along‐shelf pressure gradient
U.S. Trade Policy Lovett, William A; Alfred E. Eckes, Jr; Brinkman, Richard L
2004, 20150224, 2015-02-24
eBook
Lovett (Tulane Law School), Eckes (a former commissioner of the U.S. International Commission during the Reagan and Bush I administrations), and Brinkman (international economics, Portland State U.) ...evaluate the evolution of U.S. trade policy, focusing on the period from the establishment of the Gen
Has the current process of globalization led to a decline in nationstate sovereignty? To address this question there is a need to clarify the concepts of the nation-state and nationalism. A decline ...in U.S. nation-state sovereignty would serve to promote megacorporate power manifest in the rise of the corporate state over that of the nation-state. Evidence of U.S. nationstate decline appears in many areas, such as that of Article XVI in the WTO and policies of the IMF. The decline in nation-state sovereignty is also evident in U.S. policies of privatization manifest in the War Service Industry (WSI).
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