Changes in gill histology of fathead minnows and yellow perch transferred to soft water or acidified soft water with particular reference to chloride cells

Summary Fathead minnows, Pimephales promelas, and yellow perch, Perca flavescens, were transferred from moderately soft Lake Superior water (hardness 45mg/l as CaCO₃) to very soft diluted Lake Superior water (hardness 4.5mg/l). Sulfuric acid was added in some treatments by means of a multichannel diluter. In very soft water, chloride cells proliferated in the gills, especially in the epithelium of the secondary lamellae. When exposed to acid, chloride cells were damaged and less abundant in the secondary lamellae, and blood osmolality was reduced at pH 5.0 (x = 188 mOsm/kg, 9 days exposure; normal 280 mOsm/kg) for the minnows and pH 4.1 (x = 218 mOsm/kg, 58 days exposure; normal 329 mOsm/kg) for the perch. Certain chloride cells which form gland-like clusters in the primary lamellae of perch gills showed little damage even at pH 4.1. The present study supports the view that chloride cells proliferate in very soft fresh water to help maintain ionic balances, and that damage to these cells in acidified soft water may be related to diminished ionoregulatory capacity. The greater acid tolerance of chloride cells of, and the higher blood osmolality maintained by, perch could help to explain the greater tolerance of this species to low pH. In some cases, a species' ability to acclimate to very soft water and acidified soft water may depend upon the number, distribution, and physiology of its chloride cells.     

Structure,development and function of the branchial sieve of the common bream,Abramis brama,white bream,Blicca bjoerkna and roach,Rutilus rutilus

Synopsis The filter feeding organ of cyprinid fishes is the branchial sieve, which consists of a mesh formed by gill rakers and tiny channels on the gill arches. In order to establish its possible role during growth we measured the following morphological gill raker parameters over a range of sizes in three cyprinid fishes, bream, white bream and roach: inter raker distance, bony raker length, raker width, cushion length and channel width. At any given standard length common bream has the largest inter raker distance, roach the lowest and white bream is intermediate. In the comb model of filter feeding the inter raker distance is considered to be a direct measure of the mesh size and retention ability (= minimal size of prey that can be retained) of a filter. For the three species under study there is a conflict between the comb model and experimental data on particle retention. Lammens et al. (1987) found that common bream has a large retention ability whereas roach and white bream have a much smaller one. A new model, the channel model (Hoogenboezem et al. 1991) has been developed for common bream; in this model the lateral gill rakers can regulate the mesh size of the medial channels on the other side of the gill slit. The present data indicate that this model is not appropriate for white bream and roach. At any given standard length white bream and roach only reach 70% of the raker length of common bream, which means that in this model the gill slits should to be very narrow during filter feeding. The gill rakers consist of a bony raker and a fleshy cushion. The bony rakers have a rather long needle-like part outside the cushion in bream, but not in white bream and roach which have blunt gill rakers. Blunt gill rakers are not suited to reduce the diameter of the medial channels. The comb model seems more appropriate for white bream and roach, but doubts about the validity of this simple model remain. The sum of the areas of the medial channels is an approximation of the area through which water flows in the filter. This channel area therefore gives an impression of the capacity or flow rate of the filter. With this capacity estimation and an estimation of energy consumption we calculated an energy ratio of filter feeding. The energy ratio decreases with increasing standard length with an exponent close to the expected exponent of -0.40. The energy ratio is highest in bream, intermediate in white bream and lowest in roach.     

生物组织散射元平均间距估计的一种新方法

生物组织散射元平均间中划描述生物组织微观结构特性和生物组织超微散射特性的重要参数。本文在对生物组织超声背向散射随机模的基础上,提出了基于生物组织超声背向散射信号突变点检测的工用射元平均间距估计的新方法。该方法是生物组织超声散射分析的有效方法。     

Responses of the teleost Hoplias malabaricus to hypoxia

Synopsis Oxygen uptake (VO₂) during graded hypoxia, rate of hypoxia acclimation, breathing frequency (f_R), breath volume (V_{S, R}) and gill ventilation (V_G) were measured in Hoplias malabaricus. Normoxia and hypoxia acclimated fish had similar and constant VO₂ and V_G in a range of water PO₂ from 150 to 25 mmHg. Hypoxia acclimated fish showed significantly higher VO₂ in severe hypoxia (PO₂ <15 mmHg). Normoxia acclimated fish showed symptoms similar to hypoxic coma after 1 h of exposure to water PO₂ of 10 mmHg whereas the same symptoms were observed only at PO₂ of 5 mmHg for fish acclimated to hypoxia. Fish required 14 days to achieve full acclimation to hypoxia (PO₂ ≥25 mmHg). Lowering of water PO₂ from 150 to 25 mmHg resulted in normoxic fish showing a 3–2 fold increase in V_G. The increase was the result of an elevation in V_{S, R} rather than f_R. Among normoxia acclimated specimens, small fish showed a higher V_G per unit weight than the large ones in both normoxia (PO₂ =150 mmHg) and hypoxia (PO₂ = 15 mmHg). A decrease in the ventilatory requirement (V_G/VO₂) with increased body weight was recorded in hypoxia (PO₂ = 15 mmHg).     

Spatial separation of fishes captured in passive gear in a turbid prairie lake

Synopsis Spatial separation of fishes in the littoral zone of a turbid prairie lake (Clear Lake, Iowa) was assessed with gill nets and fyke nets. Catch per unit of effort was used to determine differences among habitat types, sampling times within a 24 h period, and sampling months. Four of 10 species examined were significantly more numerous in one of the three habitats — nonvegetated, vegetated, or gravel-rock substrate. Black bullhead (Ictalurus melas) and bigmouth buffalo (Ictiobus cyprinellus) were most abundant in vegetated areas, yellow bass (Morone mississippiensis) in gravel-rock areas, and channel catfish (Ictalurus punctatus) in both non-vegetated and gravel-rock areas. Temporal patterns in habitat use were indicated for these four species, as well as yellow perch (Perca flavescens), white bass (Morone chrysops), common carp (Cyprinus carpio), walleye (Stizostedion vitreum vitreum), black crappie (Pomoxis nigromaculatus), white sucker (Catostomus commersoni). Journal Paper No. J-11039 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. 2345. Financed by the U.S. Department of the Interior Office of Water Research and Technology and Iowa State University.     

麦草栽培姬菇配方的数学模型研究

借助二次通用旋转组合设计法研究了麦草栽培姬菇配方的数学模型,以探讨利用麦草替代棉籽壳的新配方.试验结果得出了配料的取值范围及最佳栽培配方,即麦草79％,麸皮15％,玉米粉4％,过磷酸钙1％,黄豆饼粉1％.在实际生产中很有应用价值.     

Cardiovascular and renal effects of eel and rat atrial natriuretic peptide in rainbow trout,Salmo gairdneri

Summary The renal and in vitro vascular effects of atrial natriuretic peptides have been examined in seveal species of fish. However, comparatively few investigations have described the effects of these peptides on the cardiovascular system in vivo. In the present experiments the dorsal aorta and urinary bladder were cannulated and the effects of atrial natriuretic peptides from rat and eel were monitored in conscious trout during bolus injection or continuous atrial natriuretic peptide infusion. The results show that the initial pressor effect of atrial natriuretic peptides is independent of environmental salinity adaptation (fresh or seawater) and the chemical form of atrial natriuretic peptide injected, but it is affected by the rate of atrial natriuretic peptide administration. This pressor response, and the accompanying diuresis, are mediated through -adrenergic activation. Continuous infusion of either rat or eel atrial natriuretic peptide produces a steady fall in mean arterial blood pressure, which is temporally preceded by an increase in heart rate and a decrease in pulse pressure. Diuresis induced by atrial natriuretic peptides is only partially sustained during continuous infusion. Propranolol partially blocks the increase induced in heart rate by atrial natriuretic peptides, but does not affect either pulse pressure or mean arterial pressure. Propranolol significantly increases urine flow in saline-infused animals but has no apparent effect on animals subjected to infusions of atrial natriuretic peptides. These results indicate that there are multiple foci for the action of atrial natriuretic peptides in trout and that in many instances the effects of atrial natriuretic peptides are mediated through secondary effector systems.Abbreviations ANP atrial natriuretic peptide - bw body weight - PBS phosphate-buffered saline     

Scanning and transmission electron microscopy of the squamose gill-filament epithelium from fresh- and seawater adaptedTilapia

Synopsis The architecture of the gill structure of variousTilapia species was studied in relation to their adaptability to hypersaline media. Using SEM and EM, it was shown that the squamose epithelial cells of the gills have species-typical patterns of ridges on their outer surfaces. These have previously been misinterpreted by other authors as microvilli or stereocillia. The ridges are more dense and better developed in euryhaline species, likeT. zillii, and less so in stenohaline species likeSarotherodon niloticus. Comparing freshwater and seawater-adapted individuals ofT. zillii, S. niloticus, S. galflaeus, andTristramella sacra, it was shown that in fresh water the surface cells are slightly swollen, extending over the openings of the chloride cells. During adaptation to sea water, these ridges become higher and denser and the cell surface shrinks, exposing the underlying orifices of the apical crypts of the chloride cells. The more euryhaline the species, the less change there is in the ridge pattern of the cells during passage from fresh to sea water. This evidence implicates the gill epithelium, together with the chloride cells, in the process of osmoregulation.     

New Class of Ni‐Rich Cathode Materials Li[NixCoyB1−x−y]O2 for Next Lithium Batteries

A new class of layered cathodes, Li[Ni_xCo_yB_1?x?y]O₂ (NCB), is synthesized. The proposed NCB cathodes have a unique microstructure in which elongated primary particles are tightly packed into spherical secondary particles. The cathodes also exhibit a strong crystallographic texture in which the a–b layer planes are aligned along the radial direction, facilitating Li migration. The microstructure, which effectively suppresses the formation of microcracks, improves the cycling stability of the NCB cathodes. The NCB cathode with 1.5 mol% B delivers a discharge capacity of 234 mAh g^?1 at 0.1 C and retains 91.2% of its initial capacity after 100 cycles (compared to values of 229 mAh g^?1 at 0.1 C and 78.8% for pristine Li[Ni_0.9Co_0.1]O₂). This study shows the importance of controlling the microstructure to obtain the required cycling stability, especially for Ni‐rich layered cathodes, where the main cause of capacity fading is related to mechanical strain in their charged state.