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Selected AbstractsInvestigation of the Effects of Salinity and Dietary Protein Level on Growth and Survival of Pacific White Shrimp, Litopenaeus vannameiJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2007Martin Perez-Velazquez It is presumed that in hypo- and hypersaline environments, shrimp's requirements for some specific nutrients, such as protein, may differ from those known in the marine habitat; however, few investigations have been conducted in this area of study. In the present investigation, the effects of salinity and dietary protein level on the biological performance, tissue protein, and water content of Pacific white shrimp, Litopenaeus vannamei, were evaluated. In a 3 × 4 factorial experiment, juvenile shrimp with an average initial weight of 0.36 ± 0.02 g were exposed for 32 d to salinities of 2, 35, and 50 ppt and fed experimental diets with crude protein contents of 25, 30, 35, and 40%. A significant effect of salinity on growth of shrimp was detected, with the growth responses (final weight, weight gain) ranked in the order 2 ppt (3.87, 3.50 g) > 35 ppt (3.40, 3.04 g) > 50 ppt (2.84, 2.47 g). No effects of dietary protein level or an interaction between salinity and protein on growth of shrimp were observed under the experimental conditions of this study. Percent survival of shrimp fed the highest protein content (40%, survival of 74%) was, however, significantly lower than those of shrimp fed the other feeds (25, 30 and 35% protein, survival of 99, 91, and 94%, respectively), a result likely associated with the concentration of total ammonia nitrogen, which increased significantly at increasing protein levels. Final water content of whole shrimp was significantly lower in animals exposed to 50 ppt (70.8%) than in shrimp held at 2 (73.7%) and 35 ppt (72.3%). No effect of salinity, protein, or their interaction was observed on the protein content of whole shrimp. The results of the present study are in agreement with reports of superior and inferior growth of L. vannamei reared in hypo- and hypersaline environments, respectively, as compared to what is generally observed in seawater. [source] Accumulation of DNA damage in Antarctic mosses: correlations with ultraviolet-B radiation, temperature and turf water content vary among speciesGLOBAL CHANGE BIOLOGY, Issue 2 2009JOHANNA D. TURNBULL Abstract The susceptibility of three East Antarctic moss species to UV-B radiation was examined by measuring accumulation of cyclobutane pyrimidine dimers under natural sunlight during the austral summer season of 2002/03. The 2002/03 season was characterized by unusually low springtime ozone depletion and as such our results likely underestimate the DNA damage possible in a more typical UV-B radiation season. Despite this all three species accumulated significant DNA photoproducts. We also found a positive association between photoproduct accumulation and incident UV-B radiation in the two cosmopolitan species, Bryum pseudotriquetrum and Ceratodon purpureus, with more DNA damage in samples collected early in the season compared with later in the summer. For B. pseudotriquetrum, negative associations were also observed between photoproduct accumulation and both turf water content and the 10-day mean air temperature. Photoproduct accumulation in the endemic species Schistidium antarctici was similarly high across the season and no significant association with environmental variables was found. Our results are consistent with the two cosmopolitan species having somewhat higher UV-B-screening capabilities and possibly more efficient mechanisms for repairing DNA damage than the endemic S. antarctici. [source] Salivary cortisol and psychosocial hazards at workAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 3 2009Giovanni Maina MD Abstract Background Experimental and clinical evidence suggest that stress can lead to ill-health through the disregulation of the hypothalamic,pituitary,adrenal (HPA) axis. Studies to date have produced equivocal results likely due to different methodologies and failure to account for confounding factors. This investigation aimed to assess the relation between self-reported work-related stressors and salivary cortisol and to clarify the role of the potential confounders. Methods Thirty-six call-handlers completed a self-administered job content questionnaire and collected seven daily salivary samples on two workdays and a weekend. The diurnal salivary cortisol output was expressed as cortisol awakening response (CAR), and cortisol output in the rest of the day. Salivary cortisol data were normalized by means of square root transformation. The generalized estimating equations method was used to assess the relation between job strain and cortisol levels after adjusting for gender, weekdays and adherence to the sampling schedule. Results Job strain significantly influenced the total amount of cortisol response to waking (high strain vs. low strain: 1.1 (0.3,2.0) nmol/L). The cortisol response to waking showed gender-specific differences [women excreting greater cortisol than men: 1.1 (0.3,1.9) nmol/L], and weekday differences [workdays vs. weekend: 1.0 (0.3,1.6) nmol/L]. Non-compliance with the sampling protocol was associated with lower salivary cortisol than in adherent subjects. Conclusions Our results provide further evidence for the HPA axis involvement in the physiological response to work stress. The measure of the CAR showed to be the sensitive index to assess the physiological response to psychosocial factors. Gender, weekday, and protocol compliance were confounding factors. Am. J. Ind. Med. 52:251,260, 2009. © 2008 Wiley-Liss, Inc. [source] WT1 Is Not a Reliable Marker to Distinguish Reactive from Neoplastic Astrocyte Populations in the Central Nervous SystemBRAIN PATHOLOGY, Issue 6 2010T. David Bourne MD Abstract A diagnostic difficulty in neuropathology practice is distinguishing reactive from neoplastic astrocyte populations. This is particularly true in small biopsy samples that lack evidence of increased cellularity or mitotic activity, microvascular proliferation, or necrosis. We performed the current study to validate the previously reported finding that in the central nervous system, the expression of WT1 is limited to neoplastic astrocytes. We retrospectively studied WT1 protein expression by immunohistochemistry (IHC) in 100 formalin-fixed, paraffin-embedded brain tissue samples consisting of 3 normal control tissues, 44 cases of reactive gliosis, 49 gliomas and 4 lesions suspicious for glioma. In normal human cortex, WT1 staining was restricted to vascular endothelium. Most cases of reactive gliosis (82%) showed at least focal WT1 positivity, and analysis of specimens with electrode monitoring lesions showed an inverse relationship between WT1 expression intensity and the number of days from electrode placement to tissue resection. All glioma samples (100%) and all cases suspicious for glioma (100%) showed at least focal WT1 positivity. Our results likely differ from those in the prior report because of differences in tissue fixation and IHC methodology. Thus, our findings indicate that WT1 expression alone is not a reliable feature to distinguish reactive from neoplastic astrocytes. [source] | ||||||||||