Gill membrane lipids of two bivalves presented specific regulations in response to both environmental and dietary resource variabilities. This highlights the importance of considering both trophic ...and physiological processes when studying responses to environmental stressors; an approach that can be defined as ‘trophic ecophysiology’.
Abstract
Bivalves’ physiological functions (i.e. growth, reproduction) are influenced by environmental variability that can be concomitant with trophic resource variations in terms of quality and quantity. Among the essential molecules that bivalves need to acquire from their diet to maintain physiological functions, fatty acids (FAs) such as polyunsaturated fatty acids (e.g. 20:4n-6 (arachidonic acid), 20:5n-3 (eicosapentaenoic acid) and 22:6n-3 (docosahexaenoic acid)) have been described to play a critical role. The present study examined the FA composition of gill membrane lipids of two bivalve species, Nodipecten subnodosus and Spondylus crassisquama, sampled in a coastal lagoon of the Northeastern Pacific (Ojo de Liebre, Mexico), at two contrasting locations (inner versus outer part of the lagoon) and at two different periods (February and August 2016). Spatiotemporal variations showed that FA composition of gill membrane lipids was highly correlated to FA composition of reserve lipids from digestive gland. This highlights the marked impact of the diet on FA composition of gill membranes. Interestingly, both species presented differences in the seasonal accumulations of plasmalogens and of particular FA that are not found in their diet (e.g. non-methylene interrupted FA, 22:4n-9trans, 20:1n-11), suggesting specific regulations of FA incorporation and lipid class composition in gill membranes to maintain optimal membrane function in their specific and changing environment. This study highlights the importance to characterize the spatial and temporal variability of food resources in order to apprehend the physiological consequences of environmental variability, as well as species differential regulation capacities in a changing world.
In Romania, cystic echinococcosis is endemic and affects, besides humans, various animal species including sheep, cattle, and swine. As yet, no molecular-genetic typing has been carried out to ...clearly identify the putative strains being transmitted there. Parasite samples (protoscoleces or germinal layers) were collected from infected intermediate hosts and subsequently analyzed by comparing the PCR-amplified DNA sequences of three targets: one nuclear (BG1/3) and two mitochondrial (cox1 and nadI). Three strains were identified with the mitochondrial sequences: (i) the common sheep strain (G1) which circulates between sheep and cattle and is infective for humans, (ii) the Tasmanian sheep strain (G2) infecting sheep and cattle, and (iii) the pig strain (G7) predominantly found in swine. To our knowledge, this is the first report which demonstrates the occurrence of the Tasmanian sheep strain in cattle and the sympatric occurrence of these three strains (G1, G2, and G7) in Europe.
Although laboratory experiments allow greater control of environmental conditions than field studies, they have several drawbacks. To analyze physiological responses to forcing environmental ...variables, experimental conditions should mimic natural conditions as closely as possible. For filter-feeding organisms in particular, diet quality and quantity is one of the environmental parameters that can differ markedly between experimental and field conditions. In the hatchery, Pacific oysters,
Crassostrea gigas
, commonly show good physiological performance and growth on a mixed algal diet of
Tisochrysis lutea
, formerly
Isochrysis
aff. galbana clone Tahiti (T-
Iso
), and
Chaetoceros calcitrans
, presumably as it provides a good supply of essential polyunsaturated fatty acids (PUFA) as 20:4n-6, 20:5n-3 and 22:6n-3. The present study tests whether the fluctuating biotic and abiotic conditions in the field modify the structure and function of oyster mitochondria. One group of oysters was maintained in the intertidal zone, and the other group was fed the mixed diet in a nearby experimental hatchery under salinity and temperature conditions equivalent to those in the field. After 4 weeks of conditioning, the functional capacities and membrane lipid composition of gill mitochondria were measured. For essential polyunsaturated fatty acids, only the proportion of 20:5n-3 differed between field and laboratory oysters, and confirmed the capacity of the mixed diet T-
Iso
+
C. gracilis
, to provide the essential PUFA. Nevertheless, proportions of other FA (e.g., 22:5n-6 and non-methylene-interrupted FA) differed markedly between laboratory and field-conditioned oysters. Mitochondrial oxygen uptake, cytochrome
c
oxidase activity, content of cardiolipin and concentration of cytochrome b were significantly lower in laboratory-conditioned than in field-conditioned oysters. These results indicate that laboratory conditioning, although allowing similar growth and gonad maturation, only partially mimics conditions that allow
C. gigas
to maintain mitochondrial function. Although our experimental design cannot ascertain what difference between experimental laboratory and field conditions led to changes in membrane composition and mitochondrial function, differences in nutritional quality (other than known essential PUFA) and abiotic factors (e.g., oxygen availability, emersion or daily temperature fluctuations) had a major impact on mitochondrial properties in oysters.
The field of mobility and transport has undergone major changes in recent decades, being a close link between it and the general economic development. Taking into consideration that urban areas ...concentrate the most of inhabitants and socio-economic activities, the negative effects generated by the increased road traffic are present mainly in the cities, especially in their central areas. People's involvement in awareness-raising actions on environmental issues caused by transport activity is a starting point for achieving a sustainable urban mobility system. Information and awareness of people about the link between travel behavior that they adopt and negative effects on the environment is a first step towards educating them in order to shift to sustainable mobility patterns. The paper highlights the awareness and participation component of people in the development and implementation of sustainable urban mobility plans, as an educational action for environmental protection and sustainable mobility. This concept of involving citizens is detailed within a case study.
Coupled nano-plasmons Apostol, M.; Ilie, S.; Petrut, A. ...
Applied physics. A, Materials science & processing,
05/2014, Letnik:
115, Številka:
2
Journal Article
Recenzirano
A simple model of coupled plasmons arising in two neighbouring nano-particles is presented. The coupled oscillations and the corresponding eigenfrequencies are computed. It is shown that the plasmons ...may be periodically transferred between the two particles. For larger separation distances between the two particles the retardation is included. The oscillation eigenmodes are the polaritons in this case. There are distances for which the particles do not couple to each other, i.e. the polaritonic coupling gets damped. The van der Waals-London-Casimir force is estimated for the two particles; it is shown that for large distances the force is repulsive. We compute also the polarizabilities of the two coupled nano-particles and their cross-section under the action of an external monochromatic plane wave, which exhibit resonances indicative of light trapping and field enhancement. A resonant force is also identified, acting upon the particles both on behalf of the external field and of each other.
A 30-day trial was performed to evaluate the reproductive performance of wild and 2nd generation domesticated Farfantepenaeus duorarum broodstock. Changes in biochemical composition and fatty acids ...(FA) profile in the 1st and 4th spawn order females were used as indicators of nutritional condition. Wild population of F. duorarum presented significantly better reproductive outcomes as compared to domesticated ones. Wild spawners achieved significantly higher number of eggs per spawn, number of egg per spawn per g of spawner's body weight and number of nauplii per spawn (P<0.05). Latency period was significantly shorter (P<0.05) for wild than for domesticated females (11 vs 17days). Wild spawners also presented less mortality (6 vs 12%), higher number of total spawns (51 vs 33), spawns per ablated and per spawning females as well as higher total eggs and nauplii production. On the other hand, domesticated females presented higher number of females that spawned at least once (89 vs 76%). The higher spawning activity was reflected in lower levels of acylglycerides (AG) and cholesterol content in wild hepatopancreas (HP) and ovary (OV) (P<0.05). FA profile, mainly represented by ARA, EPA and sum of n−3 were higher in hepatopancreas and ovary of wild females, however lower levels were detected in eggs as a result of a high spawning activity. Multivariate analysis performed to detected simultaneous variation in biochemical variables indicated AG as variation pattern's responsive.
► Original paper comparing the reproductive performance of wild and G2 F. duorarum. ► Interesting findings using biochemical composition/FA profile as a nutritional index. ► Multivariate analysis method contributed to explain the results. ► Wild population performed better reproductive performance.
Two analysis methods for
Z
eff
evaluation were explored using both experimental and simulated gamma-ray attenuation data. Using particle-capture reactions on composite targets to generate ...multi-monoenergetic gamma rays between 1 and 12 MeV, we demonstrate the advantage of using neural networks for effective
Z
evaluation of shielded materials in single-pixel measurements. Furthermore, we extend the analysis to 2D processing of transmission radiography and by using Geant4-simulated data we prove the superiority of artificial neural networks in terms of image quality and material discrimination against classical methods.
This review evaluates the use of the salinity stress test (SST) as an index of postlarvae (PL) quality, either at the end of experimental treatments or to predict performance during stocking and ...growout. The SST is easy to apply and does not require specialized equipment, hence its popularity. However, predictive value of the test seems to be limited to short-term performance during future culture. To determine to what extent SST depends on osmoregulation, the mechanisms in crustaceans are briefly reviewed, with particular emphasis on studies related to SST in PL penaeid shrimp. Two main physiological features of osmoregulation, active ion transport through the Na
+/K
+-ATPase pump and fatty acid composition of membranes affecting permeability to water and ions, cannot fully explain differential survival to an SST. This observation is derived from different experimental models, which include nutritional conditions or normal (genetic) variation. Other traits of the overall physiological condition appear to be involved and are not related to physiological regulation but rather are a result of a possible increased tolerance capacity.
Eyestalk ablation is the most common procedure to induce gonadic maturation in commercial hatcheries of penaeid shrimp. In addition to reproduction, other physiological and metabolic processes are ...affected by removal of the X-organ sinus gland complex located in the eyestalk. In this study, the effect of unilateral and bilateral eyestalk ablation on the concentration of several hemolymph metabolites and phenoloxidase system in female and male shrimp was investigated. As a consequence of reducing or suppressing molt-inhibiting hormone (MIH) production, the duration of the molting cycle was significantly shorter in eyestalk-ablated shrimp: bilaterally (10 days), unilaterally (17 days), and shrimp that were not ablated (24 days). Mortality was significantly higher in unilaterally (35%) and bilaterally (68%) ablated shrimp than in untreated shrimp (2%), probably caused by impairment of several physiological functions mediated by hormones from the eyestalk and direct injury of the nervous system. Males and females were affected differently by eyestalk ablation in terms of concentrations of glucose, triglycerides, and protein in hemolymph. Glucose and lactate levels were lower in bilaterally ablated shrimp, as expected by the role of crustacean hyperglycemic hormone in glucose metabolism. Cholesterol and hemocyte count were not significantly different among the three treatments. Prophenoloxidase and phenoloxidase activities were significantly lower in bilaterally, but not in unilaterally ablated shrimp. This could suggest an endocrine control of this mechanism of the effector immune response or reflect the level of physiological trauma caused by bilateral eyestalk ablation in this species.
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