981 resultados para Total length
Resumo:
Ocean acidification, as a consequence of increasing marine pCO2, may have severe effects on the physiology of marine organisms. However, experimental studies remain scarce, in particular concerning fish. While adults will most likely remain relatively unaffected by changes in seawater pH, early life-history stages are potentially more sensitive - particularly the critical stage of fertilization, in which sperm motility plays a central role. In this study, the effects of ocean acidification (decrease of pHT to 7.55) on sperm motility of Baltic cod, Gadus morhua, were assessed. We found no significant effect of decreased pH on sperm speed, rate of change of direction or percent motility for the population of cod analyzed. We predict that future ocean acidification will probably not pose a problem for sperm behavior, and hence fertilization success, of Baltic cod.
Resumo:
Determining which marine species are sensitive to elevated CO2 and reduced pH, and which species tolerate these changes, is critical for predicting the impacts of ocean acidification on marine biodiversity and ecosystem function. Although adult fish are thought to be relatively tolerant to higher levels of environmental CO2, very little is known about the sensitivity of juvenile stages, which are usually much more vulnerable to environmental change. We tested the effects of elevated environmental CO2 on the growth, survival, skeletal development and otolith (ear bone) calcification of a common coral reef fish, the spiny damselfish Acanthochromis polyacanthus. Newly hatched juveniles were reared for 3 wk at 4 different levels of PCO2(seawater) spanning concentrations already experienced in near-reef waters (450 µatm CO2) to those predicted to occur over the next 50 to 100 yr in the IPCC A2 emission scenario (600, 725, 850 µatm CO2). Elevated PCO2 had no effect on juvenile growth or survival. Similarly, there was no consistent variation in the size of 29 different skeletal elements that could be attributed to CO2 treatments. Finally, otolith size, shape and symmetry (between left and right side of the body) were not affected by exposure to elevated PCO2, despite the fact that otoliths are composed of aragonite. This is the first comprehensive assessment of the likely effects of ocean acidification on the early life history development of a marine fish. Our results suggest that juvenile A. polyacanthus are tolerant of moderate increases in environmental CO2 and that further acidification of the ocean will not, in isolation, have a significant effect on the early life history development of this species, and perhaps other tropical reef fishes
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The specific transporters involved in maintenance of blood pH homeostasis in cephalopod molluscs have not been identified to date. Using in situ hybridization and immuno histochemical methods, we demonstrate that Na+/K+-ATPase (soNKA), a V-type H+-ATPase (soV-HA), and Na+/HCO3- cotransporter (soNBC) are co-localized in NKA-rich cells in the gills of Sepia officinalis. mRNA expression patterns of these transporters and selected metabolic genes were examined in response to moderately elevated seawater pCO2 (0.16 and 0.35 kPa) over a time-course of six weeks in different ontogenetic stages. The applied CO2 concentrations are relevant for ocean acidification scenarios projected for the coming decades. We determined strong expression changes in late stage embryos and hatchlings, with one to three log2-fold reductions in soNKA, soNBCe, socCAII and COX. In contrast, no hypercapnia induced changes in mRNA expression were observed in juveniles during both short- and long-term exposure. However a transiently increased demand of ion regulatory demand was evident during the initial acclimation reaction to elevated seawater pCO2. Gill Na+/K+-ATPase activity and protein concentration were increased by approximately 15% in during short (2-11 day), but not long term (42 day) exposure. Our findings support the hypothesis that the energy budget of adult cephalopods is not significantly compromised during long-term exposure to moderate environmental hypercapnia. However, the down regulation of ion-regulatory and metabolic genes in late stage embryos, taken together with a significant reduction in somatic growth, indicates that cephalopod early life stages are challenged by elevated seawater pCO2.
Resumo:
Extensive use of fossil fuels is leading to increasing CO2 concentrations in the atmosphere and causes changes in the carbonate chemistry of the oceans which represents a major sink for anthropogenic CO2. As a result, the oceans' surface pH is expected to decrease by ca. 0.4 units by the year 2100, a major change with potentially negative consequences for some marine species. Because of their carbonate skeleton, sea urchins and their larval stages are regarded as likely to be one of the more sensitive taxa. In order to investigate sensitivity of pre-feeding (2 days post-fertilization) and feeding (4 and 7 days post-fertilization) pluteus larvae, we raised Strongylocentrotus purpuratus embryos in control (pH 8.1 and pCO2 41 Pa e.g. 399 µatm) and CO2 acidified seawater with pH of 7.7 (pCO2 134 Pa e.g. 1318 µatm) and investigated growth, calcification and survival. At three time points (day 2, day 4 and day 7 post-fertilization), we measured the expression of 26 representative genes important for metabolism, calcification and ion regulation using RT-qPCR. After one week of development, we observed a significant difference in growth. Maximum differences in size were detected at day 4 (ca. 10 % reduction in body length). A comparison of gene expression patterns using PCA and ANOSIM clearly distinguished between the different age groups (Two way ANOSIM: Global R = 1) while acidification effects were less pronounced (Global R = 0.518). Significant differences in gene expression patterns (ANOSIM R = 0.938, SIMPER: 4.3% difference) were also detected at day 4 leading to the hypothesis that differences between CO2 treatments could reflect patterns of expression seen in control experiments of a younger larva and thus a developmental artifact rather than a direct CO2 effect. We found an up regulation of metabolic genes (between 10 to 20% in ATP-synthase, citrate synthase, pyruvate kinase and thiolase at day 4) and down regulation of calcification related genes (between 23 and 36% in msp130, SM30B, SM50 at day 4). Ion regulation was mainly impacted by up regulation of Na+/K+-ATPase at day 4 (15%) and down regulation of NHE3 at day 4 (45%). We conclude that in studies in which a stressor induces an alteration in the speed of development, it is crucial to employ experimental designs with a high time resolution in order to correct for developmental artifacts. This helps prevent misinterpretation of stressor effects on organism physiology.
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Larvae of the Mediterranean pteropod Cavolinia inflexa were maintained at controlled pHT values of 8.1, 7.82 and 7.51, equivalent respectively to pCO2 levels of 380, 857 and 1713 µatm. At pHT 7.82 larvae exhibited malformations and lower shell growth, compared to the control condition. At pHT 7.51 the larvae did not make shells but were viable and showed a normal development. However, smaller shells or no shells will have both ecological (food web) and biogeochemical (export of carbon and carbonate) consequences. These results confirm that 1pteropods, as well as the species dependent upon them as a food resource, will be severely impacted by ocean acidification.
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This study of vertical fatty acid profiles, based on analysis of 58 fatty acids sampled at 3-mm intervals throughout the blubber column of a model marine mammal, the ringed seal (Pusa hispida), revealed three chemically distinct layers. The average depths of the outer and inner layers were quite consistent (~1.5 and ~1 cm, respectively). Consequently, the middle layer varied greatly in thickness, from being virtually absent in the thinnest animals to 2.5 cm thick in the fattest. The relative consistencies of the thickness and composition of the layers as well as the nature of the fatty acids making up each layer support the generally assumed function of the various layers: (1) the outer layer is primarily structural and thermoregulatory, (2) the inner layer is metabolically active with a fatty acid composition that is strongly affected by recent/ongoing lipid mobilization/deposition, and (3) the middle layer is a storage site that contracts and expands with food availability/consumption. The remarkable dynamics of the middle layer along with the discrete pattern of stratification found in the vertical fatty acid profiles have important implications for methodological sampling design for studies of foraging ecology and toxicology based on analyses of blubber of marine mammals.
Resumo:
Traditionally, many small-sized copepod species are considered to be widespread, bipolar or cosmopolitan. However, these large-scale distribution patterns need to be re-examined in view of increasing evidence of cryptic and pseudo-cryptic speciation in pelagic copepods. Here, we present a phylogeographic study of Oithona similis s.l. populations from the Arctic Ocean, the Southern Ocean and its northern boundaries, the North Atlantic and the Mediterrranean Sea. O. similis s.l. is considered as one of the most abundant species in temperate to polar oceans and acts as an important link in the trophic network between the microbial loop and higher trophic levels such as fish larvae. Two gene fragments were analysed: the mitochondrial cytochrome oxidase c subunit I (COI), and the nuclear ribosomal 28S genetic marker. Seven distinct, geographically delimitated, mitochondrial lineages could be identified, with divergences among the lineages ranging from 8 to 24 %, thus representing most likely cryptic or pseudocryptic species within O. similis s.l. Four lineages were identified within or close to the borders of the Southern Ocean, one lineage in the Arctic Ocean and two lineages in the temperate Northern hemisphere. Surprisingly the Arctic lineage was more closely related to lineages from the Southern hemisphere than to the other lineages from the Northern hemisphere, suggesting that geographic proximity is a rather poor predictor of how closely related the clades are on a genetic level. Molecular clock application revealed that the evolutionary history of O. similis s.l. is possibly closely associated with the reorganization of the ocean circulation in the mid Miocene and may be an example of allopatric speciation in the pelagic zone.
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In industrial plants, oil and oil compounds are usually transported by closed pipelines with circular cross-section. The use of radiotracers in oil transport and processing industrial facilities allows calibrating flowmeters, measuring mean residence time in cracking columns, locate points of obstruction or leak in underground ducts, as well as investigating flow behavior or industrial processes such as in distillation towers. Inspection techniques using radiotracers are non-destructive, simple, economic and highly accurate. Among them, Total Count, which uses a small amount of radiotracer with known activity, is acknowledged as an absolute technique for flow rate measurement. A viscous fluid transport system, composed by four PVC pipelines with 13m length (12m horizontal and 1m vertical) and ½, ¾, 1 and 2-inch gauges, respectively, interconnected by maneuvering valves was designed and assembled in order to conduct the research. This system was used to simulate different flow conditions of petroleum compounds and for experimental studies of flow profile in the horizontal and upward directions. As 198Au presents a single photopeak (411,8 keV), it was the radioisotope chosen for oil labeling, in small amounts (6 ml) or around 200 kBq activity, and it was injected in the oil transport lines. A NaI scintillation detector 2”x 2”, with well-defined geometry, was used to measure total activity, determine the calibration factor F and, positioned after a homogenization distance and interconnected to a standardized electronic set of nuclear instrumentation modules (NIM), to detect the radioactive cloud.
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In Queensland, stout whiting are fished by Danish seine and fish otter-trawl methods between Sandy Cape and the Queensland-New South Wales border. The fishery is currently identified by a T4 symbol and is operated by two primary quota holders. Since 1997, T4 management has been informed by annual stock assessments in order to determine a total allowable commercial catch (TACC) quota. The TACC is assessed before the start of each fishing year using statistical methodologies. This includes evaluation of trends in fish catch-rates and catch-at-age frequencies against management reference points. The T4 stout whiting TACC for 2014 was adjusted down to 1150 t as a result of elevated estimates of fishing mortality and remained unchanged in 2015 (2013 TACC = 1350 t quota). Two T4 vessels fished for stout whiting in the 2015 fishing year, harvesting 663 t from Queensland waters. Annual T4 landings of stout whiting averaged about 713 t for the fishing years 2013–2015, with a maximum harvest in the last 10 fishing years of 1140 t and a maximum historical harvest of 2400 t in the 1995. Stout whiting catch rates from both Queensland and New South Wales were analysed for all vessels, areas and fishing gears. The 2015 catch rate index was equal to 0.85, down 15% compared to the 2010–2015 fishing year average (reference point =1). The stout whiting fish length and otolith weight frequencies indicated larger and older fish in the calendar year 2014. This data was translated to show improved measures of fish survival at about 38% per year and near the reference point of about 41%. Together, the stout whiting catch rate and survival indicators show the fishery was sustainable. Earlier population modelling conducted for the year 2013 also suggested the stock was sustainable, but the estimate was only marginally above the biomass for maximum sustainable yield. Irrespective, reasons for reduced catch rates should be examined further and interpreted with precaution, particularly given the TACC has been under-caught in many years. For setting of the 2016 TACC, alternate analyses and reference points were compared to address data uncertainties and provide options for quota change. The results were dependent on the stock indicator and harvest procedure used. Uncertainty in all TACC estimates should be considered as they were sensitive to the data inputs and assumptions. For the 2016 T4 fishing year, upper levels of harvest should be limited to 1000–1100 t following procedure equation 1, with target levels of harvest at 750–850 t for procedure equation 2. Use of these estimates to set TACC will depend on management and industry intentions.
Resumo:
The aim of the present study was to determine feed intake and average weight gain and to evaluate the ruminal morphologic characteristics of Saanen kids slaughtered at 30, 45 and 60 days of age, according to a completely randomized design. Thirty-six non-castrated male Saanen kids were fed ground total ration, pelleted total ration, or extruded total ration. Feed intake and refusals were controlled daily and the animals were weighed at birth and then once a week. Newborn kids received a milk replacer and were weaned at 45 days. Immediately after slaughter, the animals were eviscerated, the entire digestive apparatus was removed from the carcass. The reticulo-rumen was separated, emptied, washed and weighed. Samples were collected from the dorsal sac, pillar area and ventral sac of the rumen, fixed for about 24h in Bouin's solution, dehydrated, embedded in Histosec and cut into 5 mu m sections. Results showed that dry matter intake (DMI) at weaning and post-weaning and weight gain were higher (P < 0.05) in animals that received the pelleted total ration. The weight of the reticulo-rumen accompanied body development and was heavier in these animals. Histologically, after weaning ruminal papillae were more developed in animals that received pelleted total ration. Length of papillae increased with increase of age. The ratio of papillary height to papillary width increased with age in the ventral sac and until weaning (P > 0.05). We conclude that the pelleting process of the total ration favored increased intake, with a 46.7% increase in weight gain and increase in rumen weight and papillae length, suggesting that best results are obtained with this processing. In general, no difference was observed between the results obtained with extruded and ground total ration, although animals fed extruded total ration showed an increase in rumen weight and papillae width. (c) 2004 Elsevier B.V All rights reserved.
Resumo:
In this study, the length-weight (LWR) parameters were estimated for six syngnathid species, including 2 seahorses and 4 pipefishes, from Ria Formosa, a temperate lagoon from the south coast of Portugal. A total of 5070 fishes were used to determine the LWR. The estimated b value ranged from 2.95 (Nerophis ophidion) to 3.36 (Syngnathus abaster). To the authors' best knowledge, LWR parameters were estimated for the first time for Nerophis ophidion and Syngnathus typhle for the Atlantic waters. Data here present are essential for management and conservation of these flagship species.
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There is great interindividual variability in the response to GH therapy. Ascertaining genetic factors can improve the accuracy of growth response predictions. Suppressor of cytokine signaling (SOCS)-2 is an intracellular negative regulator of GH receptor (GHR) signaling. The objective of the study was to assess the influence of a SOCS2 polymorphism (rs3782415) and its interactive effect with GHR exon 3 and -202 A/C IGFBP3 (rs2854744) polymorphisms on adult height of patients treated with recombinant human GH (rhGH). Genotypes were correlated with adult height data of 65 Turner syndrome (TS) and 47 GH deficiency (GHD) patients treated with rhGH, by multiple linear regressions. Generalized multifactor dimensionality reduction was used to evaluate gene-gene interactions. Baseline clinical data were indistinguishable among patients with different genotypes. Adult height SD scores of patients with at least one SOCS2 single-nucleotide polymorphism rs3782415-C were 0.7 higher than those homozygous for the T allele (P < .001). SOCS2 (P = .003), GHR-exon 3 (P= .016) and -202 A/C IGFBP3 (P = .013) polymorphisms, together with clinical factors accounted for 58% of the variability in adult height and 82% of the total height SD score gain. Patients harboring any two negative genotypes in these three different loci (homozygosity for SOCS2 T allele; the GHR exon 3 full-length allele and/or the -202C-IGFBP3 allele) were more likely to achieve an adult height at the lower quartile (odds ratio of 13.3; 95% confidence interval of 3.2-54.2, P = .0001). The SOCS2 polymorphism (rs3782415) has an influence on the adult height of children with TS and GHD after long-term rhGH therapy. Polymorphisms located in GHR, IGFBP3, and SOCS2 loci have an influence on the growth outcomes of TS and GHD patients treated with rhGH. The use of these genetic markers could identify among rhGH-treated patients those who are genetically predisposed to have less favorable outcomes.
Resumo:
The objective of this study was to review the growth curves for Turner syndrome, evaluate the methodological and statistical quality, and suggest potential growth curves for clinical practice guidelines. The search was carried out in the databases Medline and Embase. Of 1006 references identified, 15 were included. Studies constructed curves for weight, height, weight/height, body mass index, head circumference, height velocity, leg length, and sitting height. The sample ranged between 47 and 1,565 (total = 6,273) girls aged 0 to 24 y, born between 1950 and 2006. The number of measures ranged from 580 to 9,011 (total = 28,915). Most studies showed strengths such as sample size, exclusion of the use of growth hormone and androgen, and analysis of confounding variables. However, the growth curves were restricted to height, lack of information about selection bias, limited distributional properties, and smoothing aspects. In conclusion, we observe the need to construct an international growth reference for girls with Turner syndrome, in order to provide support for clinical practice guidelines.
Resumo:
Negative-ion mode electrospray ionization, ESI(-), with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was coupled to a Partial Least Squares (PLS) regression and variable selection methods to estimate the total acid number (TAN) of Brazilian crude oil samples. Generally, ESI(-)-FT-ICR mass spectra present a power of resolution of ca. 500,000 and a mass accuracy less than 1 ppm, producing a data matrix containing over 5700 variables per sample. These variables correspond to heteroatom-containing species detected as deprotonated molecules, [M - H](-) ions, which are identified primarily as naphthenic acids, phenols and carbazole analog species. The TAN values for all samples ranged from 0.06 to 3.61 mg of KOH g(-1). To facilitate the spectral interpretation, three methods of variable selection were studied: variable importance in the projection (VIP), interval partial least squares (iPLS) and elimination of uninformative variables (UVE). The UVE method seems to be more appropriate for selecting important variables, reducing the dimension of the variables to 183 and producing a root mean square error of prediction of 0.32 mg of KOH g(-1). By reducing the size of the data, it was possible to relate the selected variables with their corresponding molecular formulas, thus identifying the main chemical species responsible for the TAN values.