Recent developments and improvements in ornamental fish packaging systems for air transport

Current ornamental fish packaging systems are characterized by very high fish loading densities and high metabolic wastes in the transport water after shipment. They focus mainly on management of the quality of transport water. Recent studies using the guppy as a model fish showed that post‐shipment mortality could be reduced through enhancement of the stress resistance of the fish, and hence emphases should also be placed on the preparation of the fish for transport and recovery of the fish after shipment. Farmers can contribute significantly by applying nutritional prophylaxis before harvesting. Exporters may use the salinity stress test to identify fish lots of good quality for transport, apply health prophylaxis to eradicate parasites and optimize other techniques such as starvation of the fish or addition of salt to the transport water to enhance the stress resistance of the fish. Importers may adopt proper acclimation procedure and allow fish to recover in low salinity water to reduce post‐shipment mortality. As the main bulk of post‐shipment mortality is stress‐mediated and occurs during the 1‐week recovery period, the industry should consider revising the basis of the current warranty system for their customers, from death on arrival to cumulative mortality at 7 days post shipment (or death after 7 days, DA7), in order to cut down fish losses after shipment.     

Blood oxygen transport and hemoglobin function in three tropical fish species from northern Australian freshwater billabongs

The oxygen binding properties of whole blood and hemoglobin were studied in three phylogenetically distant tropical teleosts inhabiting freshwater billabongs that exhibit marked seasonal oxygen stratification. The water breathing saratoga (Scleropages jardinii, Family Osteoglossidae), derived from an ancient divergence of the stem line leading to all other extant teleosts, has a low blood oxygen carrying capacity, Bohr and Root effect, and a high blood oxygen affinity. Erythrocytes contain a single major hemoglobin component, and equimolar concentrations of ATP and GTP. The tarpon (Megalops cyprinoides, Family Megalopidae), a facultative air-breather, has the highest blood oxygen carrying capacity and Bohr effect, and a low blood oxygen affinity and Root effect. Erythrocytes contain a single major hemoglobin and ATP as a putative regulator of hemoglobin oxygen affinity. Barramundi (Lates calcarifer, Family Centropomidae), is an obligate water-breather with intermediate blood oxygen binding properties, and the smallest Root effect. Erythrocytes contain at least 7 hemoglobins, and equimolar concentrations of ATP and GTP. Functional properties of these three blood oxygen transport systems are considered in terms of the respiratory environment and demand for oxygen. Our interpretation supports the hypothesis that the process of speciation can lead to divergence in physiological mechanisms, irrespective of past or present selection pressures.     

Natriuretic peptide inhibition of intestinal salt absorption in the Japanese eel: physiological significance

Electrophysiological studies in vitro demonstrated the significant inhibition by natriuretic peptides (NP) of short-circuit current across the eel intestine, an important osmoregulatory organ. Inhibitory potencies of several members of the NP family were assessed by voltage-clamp determination of net transepithelial salt absorption measured as the short-circuit current I_sc across the intestine of the freshwater-adapted (FW) and seawater-adapted (SW) Japanese eel (Anguilla japonica); the order of potency of synthetic eel peptides was: amidated atrial natriuretic peptide (ANP-NH₂) > ventricular natriuretic peptide (VNP) > atrial natriuretic peptide (ANP) >> C-type natriuretic peptide (CNP). Neither the order of potency nor the absolute potencies were effected by salinity adaptation. The observed potency sequence suggests that inhibition of intestinal absorption is mediated by A-type guanylyl cyclase-coupled NP receptors. The relatively low sensitivity of the intestinal response to NP compared with circulating NP concentrations suggests a role for intestinal regulation by NP which is independent of systemic delivery from cardiac sources. A novel model, incorporating the known immunohistochemical localization of NP-ergic cells and processes in the epithelial layer of the intestine and the dissipation of the Na⁺ electrochemical gradient along the alimentary tract, is developed in which local secretion of NP (in response to a bolus of food) inhibits salt absorption across the intestine regionally in favor of increased nutrient absorption.     

Evaluation of endoscopically obtained duodenal biopsy samples from cats and dogs in an adapter-modified Ussing chamber

This study was conducted to evaluate an adapter-modified Ussing chamber for assessment of transport physiology in endoscopically obtained duodenal biopsies from healthy cats and dogs, as well as dogs with chronic enteropathies. 17 duodenal biopsies from five cats and 51 duodenal biopsies from 13 dogs were obtained. Samples were transferred into an adapter-modified Ussing chamber and sequentially exposed to various absorbagogues and secretagogues. Overall, 78.6% of duodenal samples obtained from cats responded to at least one compound. In duodenal biopsies obtained from dogs, the rate of overall response ranged from 87.5% (healthy individuals; n = 8), to 63.6% (animals exhibiting clinical signs of gastrointestinal disease and histopathological unremarkable duodenum; n = 15), and 32.1% (animals exhibiting clinical signs of gastrointestinal diseases and moderate to severe histopathological lesions; n = 28). Detailed information regarding the magnitude and duration of the response are provided. The adapter-modified Ussing chamber enables investigation of the absorptive and secretory capacity of endoscopically obtained duodenal biopsies from cats and dogs and has the potential to become a valuable research tool. The response of samples was correlated with histopathological findings.     

Evaluation of coral bleaching condition <Emphasis Type="Italic">in situ</Emphasis> using an underwater pulse amplitude modulated fluorometer

ABSTRACT:   Photosynthetic activities of hermatypic corals (28 genera, c . 68 species and c. 92 specimen) were measured in November 2000 at Sekisei lagoon, Okinawa, Japan, using an underwater pulse amplitude modulated fluorometer. Maximum quantum yield (Fv/Fm) ranged from 0.61 to 0.70 and had an average value of 0.664 (standard deviation [SD], 0.0289). Following the measurement of Fv/Fm, quantum yield (Fm'-F)/Fm' at eight-leveled actinic-light intensities were obtained from all specimens. Values of electronic transport rates (ETR) were nearly the same under low photosynthetic active radiation (PAR; µmol quanta/m² per s) condition and varied with increasing PAR. The value of ETR at 100 µmol quanta/m² per s ranged from 21.3 to 30.0 and had an average of 27.8 (SD, 2.09). In August 2001, a coral bleaching event was observed in Sekisei Lagoon. During the event, photosynthetic activities of 21 specimens of eight species (seven genera) were measured. By applying two indicators, Fv/Fm and ETR at 100 µmol quanta/m² per s obtained in August 2000, 18 of 21 specimens were suggested under the bleaching process. In case of Porites lutea , seven colonies were visually evaluated for their condition of bleaching and were found to have two 'normal', three 'slightly bleached' and two 'heavily bleached'. From the density of zooxanthellae, colonies evaluated 'normal' or 'slightly bleached' did not show an apparent difference. However, they were clearly identified by Fm/Fv and ETR at 100 µmol quanta/m² per s.     

近海渔业安全救助通信网的核心技术--传输速率对网络阻塞的影响

"近海渔业安全救助通信网"(以下简称为"安全通信网")建设开通以来,在渔业安全生产中已经发挥了重要的作用。但随着我国海洋渔业经济结构的变革,现代通信技术的飞速发展,刚刚组建的"安全通信网"日趋落后,在实际运行中引出了诸多问题,难以适应渔业生产和管理的需要。本文仅从技术角度针对"安全通信网"中出现的网络阻塞问题,阐述几点意见。     

The global distribution of wind-induced upwelling

The global distribution of wind-induced upwelling at the base of the surface Ekman layer has been computed from the COADS monthly wind stress from 1950 to 1988. In contrast to previous studies where the Ekman transport equations became invalid near the Equator, this paper computed upwelling right to the equator by incorporating friction in the surface transport equations. Comparing the seasonal changes in the equatorial upwelling between the Atlantic and the Pacific, we found that the Atlantic had the larger magnitude change while the Pacific had the larger latitudinal shift. The anomalous wind-induced upwelling/downwelling associated with El Niño were computed over several latitudinal bands in the Pacific by compositing the data from six El Nino events. By plotting the July zonally averaged upwelling anomalies in the Pacific in a latitude-time contour plot, we found northward phase propagation at about 3.5° latitude per decade in the low latitudes, a feature not found in the January upwelling. Long-term upwelling trends were computed and their potential influence on fisheries are discussed.     

Improved survival of rohu, Labeo rohita (Hamilton-Buchanan) and silver carp, Hypophthalmichthys molitrix (Valenciennes) fingerlings using low-dose quinaldine and benzocaine during transport

The effects of fingerlings immersion in low‐dose benzocaine (15 and 30 mg L⁻¹, silver carp and rohu) and quinaldine (100 μL L⁻¹ silver crap and 250 μL L⁻¹ rohu) for 1, 3 and 6 h on stress responses and survival of rohu, Labeo rohita and silver carp, Hypophthalmichthys molitrix fingerlings were evaluated in a transport simulation experiment. Both quinaldine and benzocaine showed low mortalities (0–2%). The total mortality in control (with no anaesthesia) was 30% for rohu and 14% for silver carp. Quinaldine and benzocaine‐treated fingerlings had significantly higher plasma chloride levels than the control in both species. Benzocaine, quinaldine, as well as the control, had an initial elevation of plasma cortisol levels. Benzocaine lost its effectiveness after 3 h exposure while quinaldine persisted throughout the 6 h experimental period. Both sedatives reduced bacterial build‐up compared with the control. No post‐exposure mortality was observed for any of the transport methods assessed 48 h after the treatment. This study suggests that the use of low‐dose benzocaine or quinaldine during transport has positive effect on the survival and health of rohu and silver carp fingerlings.     

Calcium Signaling is Involved in Negative Phototropism ofRice Seminal Roots简

Calcium ions(Ca2+) act as an intracellular second messenger and affect nearly all aspects of cellular life. They are functioned by interacting with polar auxin transport, and the negative phototropism of plant roots is caused by the transport of auxin from the irradiated side to the shaded side of the roots. To clarify the role of calcium signaling in the modulation of rice root negative phototropism, as well as the relationship between polar auxin transport and calcium signaling, calcium signaling reagents were used to treat rice seminal roots which were cultivated in hydroculture and unilaterally illuminated at an intensity of 100–200 μmol/(m2·s) for 24 h. Negative phototropism curvature and growth rate of rice roots were both promoted by exogenous CaCl2 lower than 100 μmol/L, but inhibited by calcium channel blockers(verapamil and LaCl3), calcineurin inhibitor(chlorpromazine, CPZ), and polar auxin transport inhibitor(N-1-naphthylphthalamic acid, NPA). Roots stopped growing and negative phototropism disappeared when the concentrations increased to 100 μmol/L verapamil, 12.500 μmol/L LaCl3, 60 μmol/L CPZ, and 6 μmol/L NPA. Moreover, 100 μmol/L CaCl2 could relieve the inhibition of LaCl3, verapamil and NPA. The enhanced negative phototropism curvature was caused by the transportation of more auxin from the irradiated side to the shaded side in the presence of exogenous Ca2+. Calcium signaling plays a key role as a second messenger in the process of light signal regulation of rice root growth and negative phototropism.     

近年黄河下游输沙功能的时空变化及其影响因素分析

黄河下游河道输沙功能受自然和人为因素的扰动,对黄河的入海泥沙通量产生深远影响。为探明近年来黄河下游河道输沙功能的演变及其主导因素,基于黄河下游河段各站点2007—2020年实测径流与泥沙资料,计算历年黄河下游河道输沙功能,并结合流域降水、水土保持和引水引沙的变化情况讨论了各因素对输沙功能演变的影响。结果表明:黄河下游河道输沙功能指标在2007—2020年显著下降了约57%,其中花园口—高村段输沙功能指标和其降幅均高于高村—艾山段和艾山—利津段; 黄河下游河道输沙功能演变的主导因素是河床粗化、水土流失综合治理面积增加和引水量增大,三者的相对贡献率分别达37.6%,21.6%,17.5%。河床粗化与引水量增大使输沙功能减弱,与水土流失综合治理对输沙功能的增强作用相反,三者综合作用下黄河下游河道输沙功能近年来呈退化趋势。