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The scallop Argopecten purpuratus is a species of high commercial interest in northern Chile and Peru. Both natural and cultured populations are located in shallow bays which are periodically subjected to decreases in the levels of dissolved oxygen and to variations in the availability of food, due to upwelling events or large-scale oscillations such as El Nino--Southern Oscillation. The aim of the present study was to evaluate how the nutritional status of A. purpuratus juveniles affects their escape capacity (as a measure of their vitality) after exposure to hypoxia cycles such as those encountered in their natural environment. For this, three feeding levels were applied for 15 days: scallops fed with a mixture of microalgae equivalent to (1) 6% or (2) 3% of their body mass and (3) unfed scallops. Subsequently, half of the individuals in each treatment underwent daily hypoxia cycles for 7 days and the other half was maintained under normoxia. After this period, using their predator, the sea star Meyenaster gelatinosus, the scallops were induced to escape, and several escape response indicators were evaluated. In general, scallops fed with the highest microalgal ration (6% of scallop mass) showed the best escape performance in terms of the reaction time to the predator, total number of claps, and clapping time and rate, closely followed by scallops fed 3% of their mass. Unfed scallops showed the poorest performance in each of these escape parameters. These results were closely related with the carbohydrate content of the adductor muscle, with unfed scallops showing the lowest content. Hypoxia exposure resulted in a decrease in escape response, and unfed scallops were the most affected. Among unfed scallops, 40% of the individuals maintained under normoxia showed an escape response, whereas only 15% of those exposed to hypoxia escaped the predator. By contrast, and regardless of environmental oxygenation, more than 90% of individuals fed with either 3% or 6% rations escaped the predator. In conclusion, when scallops are under reduced nutritional state (due to low food availability), the cyclical hypoxic periods that they encounter in the natural environment can have profound effects on their vitality, making them more vulnerable against predators. KEY WORDS: hypoxia, escape capacity, feeding level, nutrition, scallop culture, Argopecten purpuratus, INTRODUCTION Both natural and cultured populations of the scallop Argopecten purpuratus located on the north coast of Chile and Peru are increasingly exposed to costal upwelling processes during spring and [...]

Basal tearing is crucial to maintaining ocular surface wetness. Corneal cold thermoreceptors sense small oscillations in ambient temperature and change their discharge accordingly. Deletion of the cold-transducing ion channel Transient receptor potential cation channel subfamily M member 8 (TRPM8) in mice abrogates cold responsiveness and reduces basal tearing without affecting nociceptor-mediated irritative tearing. Warming of the cornea in humans also decreases tearing rate. These findings indicate that TRPM8-dependent impulse activity in corneal cold receptors contributes to regulating basal tear flow., Wetness of the ocular surface and other exposed mucosae is maintained by continuous aqueous fluid secretion produced by exocrine glands. Disturbances of this process lead to eye, mouth and vaginal [...]

The partial synthesis of the two naturally occurring compounds, 23-hydroxyoleanolic acid (hederagenin) and 24-hydroxymaslinic acid (hyptatic acid), using a regioselective cyclopalladation is presented. The regioselective cyclopalladation of the axial methyl group on C-4 of maslinic acid afforded the C-24 hydroxymethylene group because of the presence of a C-2-OR substituent while hederagenin was produced in the absence of oxygenated group.

Semisynthesis of 8,12-eudesmanolides was performed using regioselective deacetylations with lipases. Different activities of lipases enzymes as acylating agents are studied for the protection of particular hydroxyl groups, on polyhydroxy eudesmane from natural resources.

15,16-Epoxybeyerane diterpenes with acetoxy substituents undergo rearrangement reactions which were catalyzed by ruthenium acetylacetonate. The results showed that the axial substituents helped to stabilize intermediate structures that allow the formation of 8(15-9)-abeo and (8-14),13(12-16)-diabeo compounds. Epoxybeyeranes with C-12 acetoxy equatorial substituents exhibited only acetoxy group migration and nucleophilic substitution reactions.

A reaction between an ent-15-alpha,16-alpha-epoxy derivative and ruthenium acetylacetonate in chloroform results in the formation of the rearrangement products ent-kaur-15-ene derivative in 20% yield and ent-kaur-16-ene derivative in 20% yield. Proton NMR analysis indicates that chlorine is present at C-16 position with a trans-disposition relative to theent-15-alpha-hydroxy group. Deuterium labeling study reveals that the ring C opening and cyclization takes place via an aldehyde intermediate.