Melatonin in octopus (Octopus vulgaris): tissue distribution, daily changes and relation with serotonin and its acid metabolite.

Information regarding melatonin production in molluscs is very limited. In this study the presence and daily fluctuations of melatonin levels were investigated in hemolymph, retina and nervous system-related structures in the cephalopod Octopus vulgaris. Adult animals were maintained in captivity under natural photoperiod and killed at different times in a regular daily cycle.

A simple and sensitive method for determination of melatonin in plasma, bile and intestinal tissues by high performance liquid chromatography with fluorescence detection.

This paper describes the development of a simple and sensitive method for routine quantification of melatonin in low sample amounts by using standard equipment of HPLC with fluorescence detection. A double chloroform extraction with an intermediate cleaning step with 0.1N NaOH allowed to concentrate melatonin and to avoid interferences in extracts of the different tissues assayed.

Intraspecific variability in the Basal metabolic rate: testing the food habits hypothesis.

Several competing hypotheses attempt to explain how environmental conditions affect mass-independent basal metabolic rate (BMR) in mammals. One of the most inclusive and yet debatable hypotheses is the one that associates BMR with food habits, including habitat productivity. These effects have been widely investigated at the interspecific level under the assumption that for any given species all traits are fixed.

Adjusting energy expenditures to energy supply: food availability regulates torpor use and organ size in the Chilean mouse-opossum Thylamys elegans.

We studied how food abundance and consumption regulates torpor use and internal organ size in the Chilean mouse-opossum Thylamys elegans (Dielphidae), a small nocturnal marsupial, endemic in southern South America. We predicted that exposure to food rations at or above the minimum energy levels necessary for maintenance would not lead to any signs of torpor, while reducing food supply to energy levels below maintenance would lead to marked increases in frequency, duration and depth of torpor bouts. We also analyzed the relationship between food availability and internal organ mass.

Some vaguely explored (but not trivial) costs of tail autotomy in lizards.

Lizard tail autotomy is considered an efficient anti-predator strategy that allows animals to escape from a predator attack. However, since the tail also is involved in many alternative functions, tailless animals must cope with several costs following autotomy. Here we explicitly evaluate the consequences of tail autotomy for two costs that have been virtually unexplored: 1.

In vitro and in vivo evaluation of enoxaparin removal by continuous renal replacement therapies with acrylonitrile and polysulfone membranes.

Background: Enoxaparin is a low-molecular-weight heparin for which the degree of elimination through hemofilters during continuous renal replacement therapy (CRRT) is not well established.

Objective: The elimination of enoxaparin by CRRT, using acrylonitrile (AN69) or polysulfone (PS) membranes, was studied in vitro and among critically ill patients.

Methods: In vitro procedures were carried out using Ringer's lactate, bovine albumin-containing Ringer's lactate, or fresh human plasma as enoxaparin vehicle, using AN69 or PS membranes, and following continuous veno-venous hemofiltration (CVVH) or continuous veno-venous hemodialysis (CVVHD).

Thermoregulatory behavior, heat gain and thermal tolerance in the periwinkle Echinolittorina peruviana in central Chile.

The amount of solar radiation absorbed by an organism is a function of the intensity of the radiation and the area of the organism exposed to the source of the radiation. Since the prosobranch gastropod Echinolittorina peruviana is longer than it is wide, its areas of the lateral sides are approximately twice as large as the areas of the frontal and dorsal faces. We quantified the orientation of the intertidal prosobranch E.