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In central-place foragers the breeding cycle is often the period with the highest energy cost, where dietary and stored lipids play a key role. Lipids are mobilized through blood lipoproteins providing fuel to tissues. Thus, the use of food and endogenous resources with high-energy fats is important to sustain individuals' nutritional demands. To evaluate the physiological components associated to energetic demands and their variation regarding life history processes, we analysed the plasma circulating lipoprotein levels, the lipid classes and fatty acid (FA) composition in Brown Skua (Stercorarius antarcticus lonnbergi) in breeding stages with different energy requirements: incubation (In), early rearing (Er) and late rearing (Lr). We expected to find differences according to the energy demands of each stage and the sex. The level of Very Low Density lipoproteins was affected by the sex and the breeding stage, whereas Low Density lipoproteins only by the stage. Total plasma lipid content and circulating lipid classes were invariant among the stages studied; however, differences in total plasma FA and monounsaturated FA (oleic and nervonic) abundances were observed among stages. Besides, a decrease in the n-3:n-6 ratio was observed towards the Lr stage. The differences found in lipoproteins may be linked to changes in the energy demands throughout the breeding period. Moreover, the variation observed in FA abundance and n-3:n-6 ratio may be related to a preferential mobilization of FA from stores as fuel or, possibly, to a differential use of the available food resources. [ABSTRACT FROM AUTHOR]

Pomacea canaliculata and P. maculata are freshwater apple snails considered two of the most invasive alien species worldwide. They are expanding their ranges in Asia, Europe and North America, damaging crops, wetland ecosystems and endangering human health. Despite having different invasive potential, they have systematically been misidentified because of their morphological plasticity with highly variable shells, which hampers efforts to manage their spread and impact. Thus, additional work is needed to clarify species boundaries in this group of Pomacea. Here we report a new taxonomic character based on the spectroscopic characteristics of their pigmented perivitellins (egg proteins) and a fast and simple method for measuring it. The egg perivitelline fluid is analyzed via conventional agarose gel electrophoresis and the naturally-colored egg carotenoproteins are extracted, without the need for staining, and analyzed spectrophotometrically. Then, the ratio between two wavelengths (PQ) of the absorbance spectra is calculated. Results can be obtained in less than 24 h. The method was validated in the field by analysing seven populations from Asia (non-native) and South America (native) that had been genetically identified and in which PQ differed consistently between the two species. Eggs are oviposited in conspicuous reddish masses above the waterline, allowing rapid detection and easy collection of samples in the field. This novel tool would be valuable in integrative taxonomic studies to distinguish these two lineages of Pomacea and contribute to our understanding of Pomacea diversity. [ABSTRACT FROM AUTHOR]

Current anthropogenic influences threaten the permanence of eelgrass, a relevant macrophyte that brings about important ecological benefits including nursery for waterfowl and fish species, shoreline stabilization, nutrient recycling and carbon sequestration. Eelgrass restoration normally involves transplanted plots and monitoring success requires noninvasive assessments of standing stock and productivity. Allometric scaling of eelgrass leaf biomass and length can provide proxies for these assessments, but accuracy of allometric projections is mainly resultant of uncertainty propagation of parameters, so for the sake of suitability it is very important ensuring the most accurate estimates. The traditional approach for producing estimates of allometric parameters considers a linear regression model involving logarithms of the original response and explanatory variables along with a normally distributed additive error. The suitability of this method has been questioned on the ground of biased results raising nonlinear regression as a necessary amendment. Here we demonstrate that this controversy can be surpassed allowing for a logistic error structure and heteroscedasticity in the traditional method. The present arrangement delivered parameter estimates from raw data surpassing inconveniences of the traditional fitting procedure. Moreover, associated allometric proxies for average leaf biomass in shoots entailed similar reproducibilities than produced by using nonlinear regression and quality controlled data. In achieving suitable accuracy levels, the present approach required a sample of raw data of about 9% of involved in prior estimations based on quality controlled data. The improvements associated to the present approach grant highly consistent non-destructive assessments for the sake of eelgrass conservation. [ABSTRACT FROM AUTHOR]

Seasonal variations in the morphology of the parenchymal mass and function of the albumen gland/capsule gland complex have been studied in Pomacea canaliculata, together with the cellular types involved in the synthesis and secretion of perivitellin fluid components. The two major parenchymal cell types, albumen secretory cells (AS) and labyrinthic cells (LC), undergo seasonal variations throughout the annual reproductive cycle, which is divided into three periods. Both cellular types show maximal development and structural complexity during the reproductive period (spring and summer). AS cells have a well-developed Golgi complex and rough endoplasmic reticulum and their secretory granules show electron-dense particles of about 20 nm (probably galactogen). These cells are uniquely involved in ovorubin and PV2 perivitellin synthesis and their secretory granules are the single storage site for these two major perivitellins, as revealed by immunoelectron microscopy. AS also possess calcium deposits that infiltrate the cytoplasmic matrix. The luminal surfaces of LC exhibit long cilia intermingled with sparce short microvilli. Basally, the plasma membrane shows deep irregular folds that extend through the cytoplasm up to the subapical region. Calcium deposits infiltrate the cytoplasm and accumulate in the extracellular space of the basal labyrinth. Nerve terminals seem to be involved in the regulation of parenchymal cell secretion. At the post-reproductive period, AS markedly change their aspect following the release of most of the secretory granules into the acinar lumen. LC decrease in volume, the number of their cilia decreases, their cytoplasmic folds are much thinner and their extracellular spaces lack calcium particles. At the pre-reproductive period (winter), AS and LC recover and prepare for the subsequent period. [ABSTRACT FROM AUTHOR]

The effects of a water-soluble fraction of light crude oil dissolved in freshwater (WSF) on Macrobrachium borellii exposed at three life stages was evaluated. Adults, larvae (PL), and embryos were exposed to five levels of WSF for 96 h. At 48 and 72 h PL were significantly more sensitive to WSF than adults, though values for 96-h LC50 were not significantly different (1.56 and 1.41 mg/L, respectively). Mortality was never high enough to allow LC50 calculation in embryos, but chronic exposure to WSF increased the mortality near hatching and significantly decreased PL survival compared to the control group. The uptake, accumulation, and depuration of WSF were evaluated in adult prawns (lipid content 1.5% wet wt) exposed to a sublethal concentration for 96 h followed by a 10-d depuration period. Hydrocarbons were rapidly taken up, and after 24 h most of them reached an equilibrium concentration. Increases in the number and alkylation of the aromatic rings enhanced both their accumulation and their retention. When returned to clean freshwater, levels of lighter aromatics dropped rapidly over 12 h. From these studies we conclude that early life stages of M. borellii are not very vulnerable to WSF toxicity, while adults have a rapid uptake and release of most of the contaminating hydrocarbons, probably due to their low lipid levels. [ABSTRACT FROM AUTHOR]

Determines the function of the muscle tissue of the Atlantic salmon, Salmo salar. Rapid discharge of water-soluble fraction of hydrocarbons of crude petroleum from the dorsal muscle tissue; Control of the actual accumulation and release of hydrocarbons in the whole muscle tissue by adipocytes.

The article presents a study which evaluates the effects of petroleum hydrocarbon's water-soluble fraction with respect to toxicity, physiology, and tainting. The study analyzed the WSF's hydrocarbon concentrations using gas-liquid chromatography (GLC) and were extracted using Murray extraction procedure. Results show that the WSF's hydrocarbons demonstrated a GLC pattern wherein it was dominated by monoaromatic compounds.

The article Improved allometric proxies for eelgrass conservation, written by A. Montesinos-López, E. Villa-Diharce, H. Echavarría-Heras, and C. Leal-Ramírez, was originally published electronically on the publisher's internet portal (currently SpringerLink) on July 30, 2018 without open access. [ABSTRACT FROM AUTHOR]