The paper describes the synthesis, characterization data, and biological activity (antibacterial, antifungal, and brine shrimps lethality) of new azetidin-2-ones. The compounds have been synthesized ...by the reaction of diarylketenes, generated in situ from thermal decomposition of the 2-diazo-1,2-diarylethanones, with N-(1-methyl-1H-indol-3-yl)methyle neamines. The compounds have been characterized by elemental analysis and spectral (IR, super(1)H and super(13)C NMR, and MS) data. The paper also reports the results of antibacterial, antifungal, and brine shrimps lethality assays of these compounds. Some of the compounds exhibited significant biological activity .
Mangrove forests could be a simple and effective alternative to conventional sewage treatment, particularly for island communities given its low cost and low maintenance. Due to their high adaptation ...capacity, these plants are able to tolerate and bioremediate the high levels of nutrients and pollutants found in sewage water. This solution could be applied to small tropical islands with high population density such as Mayotte in the Indian Ocean. This paper reports on a trial by stable isotopic super(15)N tracing of such a bioremediation process on pre-treated wastewater near the village of Malamani, in the middle of the large coastal mangrove in the bay near Chirongui. The first results show a boost in the mangrove growth, but a longer period of observation is needed to confirm the beneficial effects, and also to clarify the role of the local crab population, whose engineering activities play an important part in the ecosystem. The exact denitrification process is not yet understood, and the mass balance equation also reveals loss of nitrogen-containing compounds, which needs to be analyzed more closely.
Six methods based on empirical estimates of surplus production are outlined which can be used to estimate the exploitation rate and biomass corresponding to Maximum Sustainable Yield (E sub(MSY) and ...B sub(MSY)). Three of these methods involve fitting production functions to surplus production, assuming that biomass and catch are measured without error, and the other three involve computing average surplus production for biomasses close to B sub(MSY) to estimate E sub(MSY). The six methods are tested using simulations based on data for two data-rich Alaskan crab stocks and are applied to data for six Alaskan crab stocks. The results suggest that, unlike stock status relative to the unfished level and Maximum Sustainable Yield, estimates of Emsy and B sub(MSY) are generally poor, with poor performance attributed mainly to production models ignoring transient age and size dynamics, and the impact of data contrast as well as the extent of process and observation error.
This article reviews the morphogenesis, morphology, histology, ultrastructure, and structural-functional relationships of the hepatopancreas, the main metabolic organ of the Decapoda. The ...hepatopancreas develops in early larval stages from a pair of lateral lobes of the midgut anlage. In adults, it consists of hundreds of blindly ending tubules that are enveloped by a muscle net consisting of longitudinal and circular fibers. Stem cells at the distal ends of the tubules give rise to three ultrastructurally different epithelial cell types, the R-, F-, and B-cells. Histochemistry, immunohistochemistry, in situ hybridization, and monitoring of ultrastructural changes under different experimental conditions allowed the attribution of functions to these cell types. R-cells serve for the absorption and metabolization of nutrients, storage of energy reserves and minerals, synthesis of lipoproteins for export to other organs, detoxification of heavy metals, and excretion of uric acid. F-cells synthesize digestive enzymes and blood proteins involved in oxygen transport and immune defense. They also detoxify some heavy metals and probably organic xenobiotics. B-cells are assumed to produce and recycle fat emulsifiers. The hepatopancreas tubules lack nerves. The presence of scattered M-cells with putative endocrine function in the epithelium suggests that the hepatopancreas is mainly hormonally controlled. M-cells probably represent a self-perpetuating cell lineage independent from E-cells. The interstitium between the tubules contains connective tissue, arterioles, hemolymph with circulating hemocytes, and fixed phagocytes that eliminate pathogens. The hepatopancreas is histologically and ultrastructurally uniform throughout the Decapoda, despite their broad variety in body size, morphology, life style, and ecology. However, in a few cavernicolous and deep-sea shrimps parts of the hepatopancreas are transformed into large oil storing and bioluminescent compartments. Within the malacostracan crustaceans, the hepatopancreas of the Decapoda is most similar to the digestive gland of the Euphausiacea, supporting close taxonomic relationship of these two taxa.
An injectable hydrogel for chondrocyte delivery was developed by blending chitosan and starch derived from various sources with b-glycerol phosphate (b-GP) in the expectation that it would retain a ...liquid state at room temperature and gel at raised temperatures. Rheological investigation indicated that the system consisting of chitosan derived from crab shell and corn starch at 4:1 by weight ratio (1.53%, w/v of total polymers), and 6.0% (w/v) b-GP (C/S/GP system) exhibited the sharpest sol-gel transition at 37 +/- 2 C. The C/S/GP hydrogel was gradually degraded by 67% within 56 days in PBS containing 0.02 mg/ml lysozyme. The presence of starch in the system increased the water absorption of the hydrogel when compared to the system without starch. SEM observation revealed to the interior structure of the C/S/GP hydrogel having interconnected pore structure (average pore size 26.4 km) whereas the pore size of the hydrogel without starch was 19.8 km. The hydrogel also showed an ability to maintain chondrocyte phenotype as shown by cell morphology and expression of type II collagen mRNA and protein. In vivo study revealed that the gel was formed rapidly and localized at the injection site.
Hydrothermal vents represent a unique habitat in the marine ecosystem characterized with high water temperature and toxic acidic chemistry. Vents are distributed at depths ranging from a few meters ...to several thousand meters. The biological communities of shallow-water vents have, however, been insufficiently studied in most biogeographic areas. We attempted to characterize the macrofauna and macroflora community inhabiting the shallow-water vents off Kueishan Island, Taiwan, to identify the main abiotic factors shaping the community structure and the species distribution. We determined that positively buoyant vent fluid exhibits a more pronounced negative impact to species on the surface water than on the bottom layer. Species richness increased with horizontal distance from the vent, and continuing for a distance of 2000 m, indicating that the vent fluid may exert a negative impact over several kilometers. The community structure off Kueishan Island displayed numerous transitions along the horizontal gradient, which were broadly congruent with changes in environmental conditions. Combination of variation in Ca2+, Cl-, temperature, pH and depth were revealed to show the strongest correlation with the change in benthic community structure, suggesting multiple factors of vent fluid were influencing the associated fauna. Only the vent crabs of Kueishan Island may have an obligated relationship with vents and inhabit the vent mouths because other fauna found nearby are opportunistic taxa that are more tolerant to acidic and toxic environments.
Isolating the relative effects of episodic disturbances and chronic stressors on long-term community change is challenging. We assessed the impact of an episodic disturbance associated with human ...visitation (boat anchoring) relative to other drivers of long-term change on coral reefs. A one-time anchoring event at Crab Cove, British Virgin Islands, in 2004 caused rapid losses of coral and reef structural complexity that were equal to the cumulative decline over 23 years observed at an adjacent site. The abundance of small site-attached reef fishes dropped by approximately one quarter after the anchoring event, but this drop was not immediate and only fully apparent two years after the anchoring event. There was no obvious recovery from the impact, and no evidence that this episodic impact accelerated or retarded subsequent declines from other causes. This apparent lack of synergism between the effect of this episodic human impact and other chronic stressors is consistent with the few other long-term studies of episodic impacts, and suggests that action to mitigate anchor damage should yield predictable benefits.
PDF
