Increased melanomacrophage centres in the liver of reproductively dysfunctional female greater amberjack Seriola dumerili (Risso, 1810)

The greater amberjack Seriola dumerili is a new aquaculture fish that may display reproductive dysfunctions. During extensive follicular atresia, which is a common reproductive dysfunction in females during vitellogenesis, part of the reabsorbed yolk returns to the liver to be metabolized and recycled. Melanomacrophage centres (MMCs) are aggregates of macrophage-like cells that play a role in the destruction, detoxification and recycling of endogenous and exogenous materials, and have been associated with systemic stress. Wild and captive-reared greater amberjack were sampled in the Mediterranean Sea during two different phases of the reproductive cycle. The liver of reproductively dysfunctional captive-reared females sampled during the spawning season showed a high density of both MMCs and apoptotic cells. A weak liver anti-cytochrome P450 monooxygenase 1A immunoreactivity was observed, suggesting that the examined fish were not exposed to environmental pollutants. We propose that the observed increase in MMCs and apoptosis in captive-reared fish was related to the hepatic overload associated to the metabolism of yolk proteins reabsorbed during extensive follicular atresia. Since follicular atresia is a frequent physiological and pathological event in teleosts, we suggest that the reproductive state should be always assessed when MMCs are used as markers of exposure to stress or pollutants.     

Haemorrhagic septicaemia in the hybrid surubim (Pseudoplatystoma corruscans×Pseudoplatystoma fasciatum) caused by Aeromonas hydrophila

Intensive culture of the hybrid surubim (Pseudoplatystoma corruscans × Pseudoplatystoma fasciatum) in Brazil is responsible for the occurrence of diseases and consequent economic losses. However, the causative agents are not well known. The objective of this study was to isolate and to characterize the pathogenic agent responsible for mortalities in cultured surubim and to demonstrate its virulence. Ten fish from a fish farm located in the Mato Grosso do Sul State (Brazil) were collected and 14 haemolytic bacteria characterized as Aeromonas hydrophila were isolated from the kidneys (eight) and brain (six). As an experimental challenge, fish weighing 98.1±23.6 g were injected with 1 mL of saline solution and 2 × 10², 2 × 10⁴, 2 × 10⁶ and 2 × 10⁸ CFU A. hydrophila mL^?1. Fish infected with 2 × 10⁸ CFU showed increased external and internal symptoms and mortality of 50±12.5% after 96 h. Increased A. hydrophila concentration was responsible for a decrease in haematocrit percentage and erythrocyte number, lymphocytes and eosinophils, as well as an increase in monocytes, neutrophils, serum agglutination titre and serum antimicrobial activity. It was concluded that A. hydrophila was responsible for characteristic symptoms of bacterial haemorrhagic septicaemia as well as important haematological and immunological alterations, which led to surubim mortality.     

Endocrine cells producing peptide hormones in the intestine of Nile tilapia: distribution and effects of feeding and fasting on the cell density

Endocrine cells (ECs) act as a luminal surveillance system responding to either the presence or absence of food in the gut through the secretion of peptide hormones. The aim of this study was to analyze the effects of feeding and fasting on the EC peptide-specific distribution along the intestine of Nile tilapia. We assessed the density of ECs producing gastrin (GAS), cholecystokinin-8 (CCK-8), neuropeptide Y (NPY), and calcitonin gene-related peptide (CGRP) in nine segments of the intestine using immunohistochemistry. Our results show that ECs immunoreactive to CCK-8, GAS, NPY, and CGRP can be found along all the intestinal segments sampled, from the midgut to hindgut, although differences in their distribution along the gut were observed. Regarding nutrient status, we found that the anterior segments of the midgut seem to be the main site responding to luminal changes in Nile tilapia. The NPY+ and CGRP+ EC densities increased in the fasted group, while the amount of CCK-8+ ECs were higher in the fed group. No effects of fasting or feeding were found in the GAS+ EC densities. Changes in ECs density were found only at the anterior segments of the intestine which may be due to the correlation between vagus nerve anatomy, EC location, and peptide turnover. Lastly, ECs may need to be considered an active cell subpopulation that may adapt and respond to different nutrient status as stimuli. Due to the complexity of the enteroendocrine system and its importance in fish nutrition, much remains to be elucidated and it deserves closer attention.     

Microalgae Encapsulation Systems for Food,Pharmaceutical and Cosmetics Applications

Microalgae are microorganisms with a singular biochemical composition, including several biologically active compounds with proven pharmacological activities, such as anticancer, antioxidant and anti-inflammatory activities, among others. These properties make microalgae an interesting natural resource to be used as a functional ingredient, as well as in the prevention and treatment of diseases, or cosmetic formulations. Nevertheless, natural bioactives often possess inherent chemical instability and/or poor solubility, which are usually associated with low bioavailability. As such, their industrial potential as a health-promoting substance might be severely compromised. In this context, encapsulation systems are considered as a promising and emerging strategy to overcome these shortcomings due to the presence of a surrounding protective layer. Diverse systems have already been reported in the literature for natural bioactives, where some of them have been successfully applied to microalgae compounds. Therefore, this review focuses on exploring encapsulation systems for microalgae biomass, their extracts, or purified bioactives for food, pharmaceutical, and cosmetic purposes. Moreover, this work also covers the most common encapsulation techniques and types of coating materials used, along with the main findings regarding the beneficial effects of these systems.     

Genetic analysis of kernel oil content in tropical maize with design III and QTL mapping

Oil content and grain yield in maize are negatively correlated, and so far the development of high-oil high-yielding hybrids has not been accomplished. Then a fully understand of the inheritance of the kernel oil content is necessary to implement a breeding program to improve both traits simultaneously. Conventional and molecular marker analyses of the design III were carried out from a reference population developed from two tropical inbred lines divergent for kernel oil content. The results showed that additive variance was quite larger than the dominance variance, and the heritability coefficient was very high. Sixteen QTL were mapped, they were not evenly distributed along the chromosomes, and accounted for 30.91% of the genetic variance. The average level of dominance computed from both conventional and QTL analysis was partial dominance. The overall results indicated that the additive effects were more important than the dominance effects, the latter were not unidirectional and then heterosis could not be exploited in crosses. Most of the favorable alleles of the QTL were in the high-oil parental inbred, which could be transferred to other inbreds via marker-assisted backcross selection. Our results coupled with reported information indicated that the development of high-oil hybrids with acceptable yields could be accomplished by using marker-assisted selection involving oil content, grain yield and its components. Finally, to exploit the xenia effect to increase even more the oil content, these hybrids should be used in the Top Cross^™ procedure.     

Dough thermo-mechanical properties: influence of sodium chloride, mixing time and equipment

Thermo-mechanical properties of doughs prepared from common wheat flour were investigated under different kneading conditions and with different amounts of sodium chloride. Dynamic mechanical thermal analysis showed that high-speed mixing and the addition of salt to dough slowed heat-induced reactions such as starch gelatinisation and protein coagulation. The effect of dough mixing technology was more significant than the amount of sodium chloride in modifying dough rheological characteristics.     

The biomass–density relationship in seagrasses and its use as an ecological indicator

Background

Biomass–density relations have been at the centre of a search for an index which describes the health of seagrass meadows. However, this search has been complicated by the intricacy of seagrass demographics and their complex biomass–density relations, a consequence mainly of their modular growth and clonality. Concomitantly, biomass–density upper boundaries have been determined for terrestrial plants and algae, reflecting their asymptotic maximum efficiencies of space occupation. Each stand’s distance to its respective biomass–density upper boundary reflects its effective efficiency in packing biomass, which has proved a reliable ecological indicator in order to discriminate between taxonomic groups, functional groups and clonal vs. non-clonal growth.

Results

We gathered data from 32 studies on 10 seagrass species distributed worldwide and demonstrated that seagrasses are limited by their own boundary line, placed below the boundaries previously determined for algae and terrestrial plants. Then, we applied a new metric—d_grass: each stand’s perpendicular distance to the seagrass boundary—and used this parameter to review fundamental aspects such as clonal growth patterns, depth distribution, seasonality, interspecific competition, and the effects of light, temperature and nutrients.

Conclusions

Seagrasses occupy space less efficiently than algae and terrestrial plants. Using only their biomass and density data we established a new and efficient tool to describe space occupation by seagrasses. This was used with success to evaluate their meadows as an ecological indicator for the health of coastal ecosystems.

     

Effect of age and different doses of dietary vitamin E on breast meat qualitative characteristics of finishing broilers

The supplementation of vitamin E on broiler chicken diets is essential to the prevention of lipid oxidation reactions in the meat and improvement of meat quality. The objective of this study was to assess the effect of different doses of dietary vitamin E on breast meat quality of broiler chickens in the finishing period. Five doses of vitamin E were used (30, 90, 150, 210, and 270 mg/kg feed) in broilers'' diets from 42 to 54 d of age. A completely randomized design was conducted, followed by a split-plot, where the vitamin E dose was considered as the whole plot, and broilers’ age at slaughter was the subplot. Breast meat quality was assessed at 4 different ages (45, 48, 51, and 54 d old), using 50 birds per age, totaling 200 birds. Meat quality characteristics evaluated were: pH at 24 h post mortem, color (brightness, redness, and yellowness), water holding capacity, cooking loss, shear force, and lipid peroxidation. There was no interaction between age and dose of vitamin E for meat quality characteristics (P > 0.05). The age at slaughter had a quadratic effect (P < 0.05) on pH, brightness, redness, and water holding capacity. Although pH values were higher in the breast meat of older birds (51 and 52 d old), breast meat of younger birds (48 d) had a more reddish aspect. Shear force value was higher in breast meat of birds slaughtered at later ages (P < 0.01), as a linear age-effect was observed. Brightness increased linearly (P < 0.05) with higher vitamin doses, whereas treatments did not alter yellowness, cooking loss, and lipid peroxidation. In this study, increasing vitamin E doses in the finishing period increased the brightness of broiler breast meat, whereas slaughtering at later ages resulted in greater meat pH and shear force value.     

A 4-week repeated oral dose toxicity study of dairy fat naturally enriched in vaccenic, rumenic and α-linolenic acids in rats

Few studies have focused on the toxicological risks of dairy fat intake. A standard dairy fat (SDF) with a 70% SFA content and a naturally enriched dairy fat (EDF) in vaccenic, rumenic and α-linolenic acids and low in SFA (54%) have been examined in a 4-week repeated dose oral toxicity study as a daily dose of 2000 mg/kg bw by gavage in rats. Comparisons were established with a third group of rats (control) which did not receive fat administration. Both fats were well tolerated, and no adverse events or mortality were observed during the treatment nor after a 2-week observation period. EDF and SDF did not cause significant differences with respect to a control group in body weight gain, food consumption, clinical observations, organ weight ratios, histopathological findings and most of the hematological and biochemical parameters including total cholesterol and cholesterol fractions in plasma. In rats treated with SDF, a significant increase of triglycerides was observed as compared to the control group. By contrast, in rats treated with EDF, a significant decrease in triglycerides was detected. EDF orally administered to rats was safe, and no treatment-related toxicity was detected. The results also suggest that EDF could protect against the increase of triglyceride concentrations in plasma.