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91.
Pieter M. Verbost Gert Flik James C. Fenwick Anna-Maria Greco Peter K. T. Pang Sjoerd E. Wendelaar Bonga 《Fish physiology and biochemistry》1993,11(1-6):205-215
The branchial Ca2+ uptake by teleost fish is under inhibitory control by the hormone stanniocalcin (STC) which is generated by the corpuscles
of Stannius (CS). Removal of the CS in North American eel, Anguilla rostrata LeSueur, induced a rapid rise in blood calcium levels. Branchial Ca2+ influx following the extirpation of the CS (stanniectomy, STX) increased during the first four days and stayed elevated thereafter
(in agreement with previous studies). The transepithelial potential (TEP) across the gills did not change after STX and this
means that the electrochemical gradient for Ca2+ is less favourable for passive influx of Ca2+ in STX eel. Therefore, the Ca2+ influx in STX eels is a transcellular flux, with Ca2+ crossing the apical and basolateral membrane barrier. The kinetics of ATP-driven Ca2+-transport across basolateral plasma membranes from eel gills did not change after STX. Thus, the increased Ca2+-influx after STX is not correlated with changes in ATP-dependent Ca2+-extrusion across the basolateral membrane, suggesting a regulation at the apical membrane. Moreover, STC did not affect ATP-driven
Ca2+-transport in isolated basolateral membranes (in vitro). STC (0.1 nM) reduced cAMP levels in dispersed eel gill cells. It had no significant effect on the IP3 levels in these cells. We postulate that STC controls the permeability to Ca2+ of the apical membranes of the Ca2+ transporting cells of fish gills by controlling second messenger operated Ca2+ channels in the apical membrane.
Résumé L'entrée de calcium au niveau des branchies est sous le controle inhibiteur de la stanniocalcine (STC) qui est synthétisée au niveau des corpuscules de Stannius (CS). L'ablation des CS chez l'anguille d'Amérique du Nord, Anguilla rostrata LeSueur, induit une augmentation rapide des niveaux de calcium dans le sang. Le flux entrant branchial de calcium consécutif à l'ablation des CS (stanniectomie, STX) augmente pendant les 4 premiers jours et reste élevé au-delà (en accord avec des études antérieures). Le potentiel transépithélial (TEP) à travers les branchies ne change pas après STX, ceci indiquant que le gradient électrochimique du Ca2+ est moins favorable pour le flux entrant passif du Ca2+ chez l'anguille STX. En conséquence, le flux entrant de Ca2+ chez l'anguille STX est un flux transcellulaire, avec le Ca2+ traversant la barrière membranaire apicale et basolatérale. La cinétique du transport de Ca2+ conduit par l'ATP à travers les membranes plasmatiques basolatérales de branches d'anguille n'est pas modifiée après STX. Ainsi, l'augmentation du flux entrant de Ca2+ après STX n'est pas corrlée avec des modifications de l'excrétion de Ca2+ conduit par l'ATP à travers la membrane basolatérale, suggérant donc une régulation au niveau de la membrane apicale. De plus, la STC ne modifie pas le transport de Ca2+ conduit par l'ATP dans des membranes basolatérales isolées (in vitro). La STC (0.1 nM) réduit les niveaux d'AMPc dans des cellules dispersées de branchies d'anguille. Cette hormone n'a pas d'effet significatif sur les niveaux d'IP3 dans ces cellules. Nous suggérons que la STC régule la perméabilité au Ca2+ des membranes apicales des cellules branchiales transporteuses de Ca2+ en controlant un second messager agissant sur les canaux calciques de la membrane apicale.相似文献
92.
Experiments for the production of hybrid striped bass (HSB) in in-pond circulation systems (IPCS) were carried out in 2003
and 2004. The circulation system consisted of two channels with a productive volume of 8.5 cubic meters each. The tanks were
installed tightly in a pond, which served for the biological cleaning of the expiry water. In the first year HSB fingerlings
with an average weight of 46.4 g were produced. The average yield in the basin was 51.2 kg/m3. The survival rate from stocked 0.44 g advanced fry was 97.8%. The food conversion was 1.16.
In 2004 two-year-old HSB were reared in the same IPCS. The tanks were stocked at two different stocking densities, 122 and
244 fingerlings/m3 with a mean weight of 36.5 g. In the tank with the larger stocking density, the yield was almost exactly twice as high as
in the other tank (50.0 resp. 24.8 kg), which corresponded to a stocking density of 59.1 or 29.3 kg/m3 at the end of the rearing season. The stocking density had no influence on the increase of the individual body weight. Obviously
HSB can therefore still be reared at higher stocking densities. 相似文献
93.
Clare Greathead Paolo Magni Jan Vanaverbeke Lene Buhl‐Mortensen Urszula Janas Mats Blomqvist Johan A. Craeymeersch Jennifer Dannheim Alexander Darr Steven Degraer Nicolas Desroy Annick Donnay Yessica Griffiths Ivan Guala Laurent Guerin Hayley Hinchen Celine Labrune Henning Reiss Gert Van Hoey Silvana N.R. Birchenough 《水产资源保护:海洋与淡水生态系统》2020,30(7):1253-1275
- There is concern across the International Council for the Exploration of the Sea (ICES) region that a consideration of vulnerable components and the wider support mechanisms underpinning benthic marine ecosystems may be lacking from the process of marine protected area (MPA) designation, management and monitoring.
- In this study, MPAs across six European ecoregions were assessed from a benthic ecology perspective. The study included 102 MPAs, designated by 10 countries, and focused on three aspects regarding the role of the benthos in: (i) the designation of MPAs; (ii) the management measures used in MPAs; and (iii) the monitoring and assessment of MPAs.
- Qualitative entries to a questionnaire based on an existing framework (EU project ‘Monitoring Evaluation of Spatially Managed Areas’, (MESMA) were collected by 19 benthic experts of the ICES Benthic Ecology Working Group. A pedigree matrix was used to apply a numerical scale (score) to these entries.
- The results showed clear differences in scores between ecoregions and between criteria. The designation‐phase criteria generally achieved higher scores than the implementation‐phase criteria. Poor designation‐phase scores were generally reiterated in the implementation‐phase scores, such as scores for assessment and monitoring.
- Over 70% of the MPA case studies were found to consider the benthos to some extent during selection and designation; however, this was not followed up with appropriate management measures and good practice during the implementation phase.
- Poor spatial and temporal coverage of monitoring and ineffective indicators is unlikely to pick up changes caused by management measures in the MPA. There is concern that without adequate monitoring and adaptive management frameworks, the MPAs will be compromised. Also, there could be an increased likelihood that, with regard to the benthos, they will fail to meet their conservation objectives.
- This assessment was successful in highlighting issues related to the representation and protection of the benthos in MPAs and where changes need to be made, such as expanding the characterization and monitoring of benthic species or habitats of interest. These issues could be attributable to an ongoing process and/or an indication that some MPAs only have ‘paper protection’.
94.
95.
96.
This paper offers a historical analysis of contemporary practices of shopping for vegetables in the highly dynamic context of urban Hanoi during the period from 1975 to 2014. Focusing on everyday shopping practices from a food safety perspective, we assess the extent to which the policy-enforced process of supermarketization has proven to be an engine of change in daily vegetable purchasing while improving food safety. In depicting transitions in shopping practices, we combine a social practices approach with historical analysis. Providing a historical analysis of a broad and complex spectrum of everyday practices of purchasing fresh vegetables, we identify the key drivers of change. We discuss different modalities of shopping and demonstrate that no single retail modernization format can be said to exist. Rather than contrasting an idealized supermarket model with the traditional modalities of food shopping, we offer a varied, more diverse set of shopping practices that displays different strategies for coping with food safety issues. When discussed from a historical perspective, food practices are shown to be highly dynamic, being constantly reinvented and reconfigured by consumers who use their established skills, routines, and social networks to sometimes resist top-down enforced supermarketization while developing the coping strategies that best suit their local circumstances. 相似文献
97.
Lorenzo Maggioni Roland von Bothmer Gert Poulsen Elinor Lipman 《Genetic Resources and Crop Evolution》2018,65(1):137-159
The domestication process of Brassica oleracea L. has not been fully clarified, either regarding its initial location or the progenitor species involved. Two alternative hypotheses proposed so far point to either a northwest European or a Mediterranean location. Previous studies to clarify the domestication process focused on linguistic aspects and on the earliest occurrences in ancient literature of words referring to B. oleracea. Those studies are here extended to offer a comprehensive account of literary occurrences of the brassica vegetables in ancient Greek and Latin texts, between the VI century B.C.E. and the IV century C.E. This study offers a contribution to ancient ethnobotanical knowledge in the Mediterranean, including agricultural practices and culinary and medicinal uses. It also defines the time when increasing diversity of crop varieties is documented and it adds weight to the hypothesis of a Mediterranean location of the domestication of B. oleracea. 相似文献
98.
Nigussie Haregeweyn Jean Poesen Jan Nyssen Gerard Govers Gert Verstraeten Joris de Vente Jozef Deckers Jan Moeyersons Mitiku Haile 《CATENA》2008
In Tigray-northern Ethiopia, lack of sediment yield data and appropriate methodologies for predicting sediment yield have contributed to poor planning resulting in rapid sedimentation in reservoirs and storage capacity loss. The objectives of this study were: (1) to assess the spatial variability of absolute sediment yield (SY) and area-specific sediment yield (SSY) and to identify their controlling factors for 11 representative catchments and (2) to develop models to predict sediment yield. We quantified sediment yield from reservoir sediment surveys and studied the role of bio-physical characteristics of the catchments and their interactions in controlling SY and SSY variability. 相似文献
99.
Ixodid ticks remain attached to their hosts for several days to weeks. During this extended feeding process new proteins involved in the modulation of host immune responses are expressed in tick salivary glands. In our study a stimulatory or inhibitory effect of salivary gland extracts (SGE) of unfed and partially fed female Ixodes ricinus (Linnaeus, 1758), female and male Amblyomma variegatum (Fabricius, 1794) and Rhipicephalus appendiculatus Neumann, 1901 ticks on human lymphocyte proliferation induced by Concanavalin A (ConA) and phytohaemagglutinin (PHA), respectively, was investigated. SGE of all female ticks examined suppressed proliferation of ConA-induced lymphocytes; highly significant suppression was observed in the presence of unfed I. ricinus and 9-day fed A. variegatum SGE. SGE of partially fed A. variegatum and I. ricinus females suppressed PHA responses of lymphocytes. Lymphocytes showed reduced PHA and ConA responses in the presence of SGE of unfed and 2-day fed R. appendiculatus females, while SGE of 6-day fed females enhanced PHA responses, but reduced their ConA responses; generally SGE of 2-day fed females displayed the strongest inhibition. Amblyomma variegatum male SGE slightly enhanced PHA, but significantly reduced ConA responses of lymphocytes and their inhibitory effect increased during feeding. SGE of unfed and 2-day fed R. appendiculatus males enhanced PHA and ConA responses and those of 6-day fed males suppressed lymphocyte proliferation. The results suggest that (i) species- and sex-specific differences exist in the effects of tick salivary gland antigens on human lymphocyte proliferation and (ii) effect of SGE on human lymphocyte responses to mitogens varies depending on the tick feeding status. 相似文献
100.
L Haar 《Science (New York, N.Y.)》1972,176(41):1293-1296