This review focuses on the different criteria currently used to assess offspring quality of penaeid shrimp and the factors that affect this characteristic. The term ‘larval quality’ generally refers ...to the physiological condition of the larvae and is related to survival and growth rates during several larval developmental stages. The criteria fit into five general categories, depending on the approach used: biochemical, morphological, behavioral, production and survival to stress tests. Several variables at the broodstock management level are known or suspected to affect larval quality. These include variables that can be more easily controlled by producers or researchers than others. Broodstock nutrition is probably the best reviewed aspect and is supported by many papers on the metabolism of several components during maturation, use of fresh vs. artificial food and specific requirements of particular components, such as lipids and vitamins. Endocrine control of reproduction has been widely studied in crustaceans. Eyestalk ablation still represents the most commonly used endocrine manipulation to induce maturation and spawning. Other alternatives are considered although few evaluate larval quality and none has been used in production. More recently, the use of captive broodstock and genetic improvement programs have gained importance. The effect of other biological characteristics of shrimp, such as age and size, season of the year when induced to intensive maturation conditions, time spent in maturation tanks and consecutive spawnings are also considered.
This paper presents the investigation work on different polymeric materials used as insulation materials of conductors in a multicore instrumentation cable. Among differently colored materials, only ...the white one presented cracks after a few years of use. Isothermal and non-isothermal DSC measurements were performed on initial (non-used) and aged (in service used or laboratory aged) materials as well as on raw materials in order to characterize their stability and the ageing state after storage, use in service or laboratory ageing. As shown by the oxidation induction time values, a pronounced antioxidant loss occurred for all materials during storage or service; plus a strong effect of the ambient light on stability was observed for the white insulation material. Around 3% of filler, consisting mainly of TiO
2 particles (as revealed by SEM-XRF elemental analysis), was found in the white material. The higher degradability of the white material can be related to both the photocatalytic effect of the TiO
2 particles and rapid loss of stabilizers.
Juvenile Pacific whiteleg shrimp reared in either outdoor concrete tanks or indoor plastic tanks were exposed to a repeated stress induced by daily handling for 4 weeks. Metabolic responses (glucose, ...lactate, total protein, cholesterol, triglyceride, total lipid, hemocyanin, and carotenoid content) and immune responses (total hemocyte count, superoxide anion production, and superoxide dismutase activity) were compared with unstressed shrimp. Metabolic responses of stressed shrimp were different in concrete tanks than in plastic tanks. Stressed shrimp from concrete tanks had significantly lower concentrations of total proteins, triglycerides, and total lipids in hemolymph and a significantly lower concentration of carbohydrates in muscle. Stressed shrimp from plastic tanks showed higher concentrations of glucose in hemolymph and higher concentrations of total lipids, but lower concentrations of carbohydrates in the hepatopancreas. Immune responses did not present any significant differences between stressed and unstressed shrimp raised in either experimental system, suggesting that repeated stress does not depress immune response capacity, with the exception of lower levels of total protein in hemolymph. Lower amounts of disturbance occurring in outdoor unstressed shrimp, as well as natural food availability for outdoors tanks could partially explain differences in metabolic responses.
Cultivation of whiteleg shrimp (
Litopenaeus vannamei) is now entirely based on closed life-cycle populations, yet few studies have analyzed gonadal development in domesticated shrimp during grow-out ...in ponds. To determine the effect of age and weight on morphometric, histological, and biochemical variables associated with male and female gonadal development, shrimp from the same cohort, at ages of 6, 8, 10, and 12
months were examined using body weight as a covariable in an ANCOVA design. An additional comparison between two grow-out conditions in 1-year-old shrimp was done to separate the effect of size as a result of initial stocking densities. Age-related growth of gonads was clearly dependent on somatic growth for females but not for males, although differential somatic growth produced by stocking densities explained differences in growth of gonads for both sexes. Increase in oocyte diameter and differentiation associated with age and grow-out condition were independent of body weight. Age-related female gonadal development was accompanied by increases in lipid and protein concentrations, independent of body weight. Maturation of male reproductive organs (testicle, vas deferens, terminal ampoule, and spermatophore) was sequential and depended mainly on age, although body weight could explain differences caused by different grow-out conditions. An age-related decrease in concentration of lactate occurred in all male reproductive organs and could indicate a metabolic adjustment of sperm anaerobic metabolism and lactate clearance associated with gonadal development. We highly recommend waiting for optimal reproductive potential of females at 12
months to enhance spawning frequency and larval quality. At this age, body weight seems to be of secondary importance, although optimal conditions of cultivation are necessary to have adequate growth and balanced nutrition.
Juvenile shrimp were individually exposed during 24 h to 0.007 (control), 0.36, 1.07, and 2.14 mmol/l total ammonia-N at 28°C and 39 ppt salinity. After 22 h of ammonia-N exposure, oxygen consumption ...was measured for 2 h, and then hemolymph, hepatopancreas, and muscle tissues were sampled. Oxygen consumption, and levels of lactate and glycogen in the hepatopancreas increased significantly at the highest ammonia-N concentration. Concentration of oxyhemocyanin, acylglycerol, and cholesterol in hemolymph, and lactate in muscle decreased significantly in the group exposed to the highest ammonia levels. The changes observed in hemolymph and tissue metabolic fuels suggest a reduced use of carbohydrate through anaerobic metabolism and an increase in the use of lipids to satisfy the metabolic demand.
Anthracyclines are used in breast cancer both in early and advanced stages and their recommendation together with taxanes, either concurrently or sequentially, is debatable and individualized by ...phenotype. Circulating biomarkers have already been introduced in clinical practice for metastatic disease monitoring. We questioned whether it might be a role for these markers in neoadjuvant and adjuvant settings too and a general review was conducted. CK18 and CTC were found predictive for anthracycline related response in preoperative setting. Soluble E-cadherin is promising, a retrospective analysis showing a direct correlation with clinical response. CEA, CA 15-3 and HER2 ECD are not of interest for their predictive role.
Taking into account the legal prescriptions which are in force and the new regulatory requirements that will be mandatory to implement in the near future regarding testing characteristics of ...automotive fuel tanks, resulted the necessity to develop a new testing methodology which allows to estimate the behaviour of the closing system of automotive fuel tank over a long period of time (10-15 years). Thus, were designed and conducted accelerated tests under extreme assembling and testing conditions (high values for initial tightening torques, extreme values of temperature and pressure). In this paper are presented two of durability tests which were performed on an optimized closing system of fuel tank: (i) the test of exposure to temperature with cyclical variation and (ii) the test of continuous exposure to elevated temperature. In these experimental tests have been used main components of the closing system manufactured of two materials variants, both based on the polyoxymethylene, material that provides higher mechanical stiffness and strength in a wide temperature range, as well as showing increased resistance to the action of chemical agents and fuels. The tested sample included a total of 16 optimized locking systems, 8 of each of 2 versions of material. Over deploying the experiments were determined various parameters such as: the initial tightening torque, the tightening torque at different time points during measurements, the residual tightening torque, defects occurred in the system components (fissures, cracks, ruptures), the sealing conditions of system at the beginning and at the end of test. Based on obtained data were plotted the time evolution diagrams of considered parameter (the residual tightening torque of the system consisting of locking nut and threaded ring), in different temperature conditions, becoming possible to make pertinent assessments on the choice between the two types of materials. By conducting these tests and interpreting the obtained results, it can be created a clear picture of the capacity of closing system of fuel tank to fulfil the functional requirements following the exposure to values of testing parameters significantly above the values that may appear throughout the entire service life of the vehicle. The proposed accelerated testing method shows the main advantage of simulation in a limited time all the situations which may be encountered in a much longer period of time, namely the service life of the vehicle.
A method is presented for calculating the expected number of counts in peaks that have a large relative peak-area uncertainty and appear in measured gamma-ray spectra. The method was applied to ...calculations of the correction factors for peaks occurring in the spectra of radon daughters. It was shown that the factors used for correcting the calculated peak areas to their expected values decrease with an increasing relative peak-area uncertainty. The accuracy of taking the systematic influence inducing the correction factors into account is given by the dispersion of the correction factors corresponding to specific peaks. It was shown that the highest accuracy is obtained in the peak analyses with the GammaVision and Gamma-W software.
•The results of peak analysis programs were tested on a statistical basis.•Peak areas with a large statistical uncertainty were tested for their trueness.•The test was performed on five different programs for analyzing the spectra.•It was found that peak areas with a large statistical uncertainty are too large.•A way, how to calculate uncertainty-dependent correction factors is described.
Ante-mortem stress is recognized as one of the factors that could reduce shelf life in fish, although this topic has been scarcely addressed in crustaceans, particularly in cultivated penaeid shrimp ...where common harvest practices involves stressful conditions such as chasing, emersion, and confinement. This study analyzes indices of freshness in shrimp in response to such practices before storage in ice for six days. During ice storage, several indicators follow the typical postmortem pattern, although most of them (hypoxanthine, change in pH, and color) did not reach critical levels at day 6. Adenosine-5'-triphosphate (ATP) and degradation products (adenosine monophosphate, AMP, and inosine monophosphate, IMP), as well as several indicators of freshness (pH, expressible water, hardness, color, and the overall fatty acid composition) were not significantly affected by harvest. Other variables such as lower springiness, higher hypoxanthine, lipid hydroperoxides, and 20:4n-6/20:5n-3 ratio were observed in shrimp subjected to common harvest practices. However, under the current conditions of harvesting, these effects were marginal and probably do not substantially affect meat quality for human consumption, but care should be taken at higher environmental temperatures (e.g. harvest in summer) and for a duration of ice-storage over 6 days.
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