Cadmium dynamics in fish: pulse studies with 109Cd in female zebrafish, Brachydanio rerio

The dynamics of a subtoxic pulse of non-dietary ¹⁰⁹Cd was followed for up to 304 days after the exposure period in female zebrafish. The retention of dietary ¹⁰⁹Cd was also estimated.
The distribution of ¹⁰⁹Cd was studied by autoradiography, whole-body analysis and tissue sampling. After exposure to non-dietary ¹⁰⁹Cd for 10 days there was a rapid loss of ¹⁰⁹Cd from the gills. The ¹⁰⁹Cd content of the alimentary canal exceeded that which could have been expected from normal drinking. Based on the distribution pattern of non-dietary ¹⁰⁹Cd in tissues, two groups of tissues were distinguished:

• (i)

  the gills, alimentary canal and heart which showed maximum ¹⁰⁹Cd values directly after exposure, followed by a pronounced decrease up to day 21;
• (ii)

  the liver, kidney, ovary and muscle, in which there was a delay in maximum ¹⁰⁹Cd activity to days 21–42, with subsequent loss.

Small amounts of ¹⁰⁹Cd were noted in fry and fertilized eggs originating from zebrafish exposed to non-dietary ¹⁰⁹Cd. After exposure to dietary ¹⁰⁹Cd, less than 5% was retained in the zebrafish body, mainly in the alimentary canal.     

桃小食心虫幼虫的消化道和马氏管的显微结构观察

利用光学显微镜和扫描电子显微镜,在形态学和组织学水平上研究_『桃小食心虫 Carposina sasakii 幼虫消化道和屿氏管的结构.桃小食心虫幼虫消化道由前肠、中肠和后肠组成.前肠细短,肌肉层薄.前肠与中肠交界处有突出的胃盲囊.中肠长且粗大,内有围食膜,肠壁细胞较大,外层为发达的环肌和纵肌.后肠上皮细胞内陷很深.6根念珠状的马氏管位于中、后肠分界处.     

Structural observations on the alimentary canal of Paranthessius anemoniae, a copepod associate of the snakelocks anemone Ammonia sulcata

Light and electron microscopy has shown the alimentary canal of Paranthessius to be composed of clearly defined foregut, midgut and hindgut regions. The spacious foregut is cuticle-lined and separated from the midgut by a valve. The midgut epithelium is composed of columnar cells with an apparent secretary/absorptive rôle, and amoeboid cells thought to engulf material from the lumen. The amoeboid cells have large electron-dense central vacuoles containing carbohydrate-and protein-staining material. These cells appear to be sloughed off into the lumen to form part of a faecal pellet. Apart from their digestive rôle the midgut cells store lipid and it is considered possible that they have an osmoregulatory function. The hindgut epithelium cell type, lacks a cuticular layer and is thought to be mainly concerned with absorption. The alimentary canal is surrounded by strands of longitudinal and circular muscle.     

光滑足距小蠹消化道的解剖结构

采用体视显微和扫描电镜技术研究光滑足距小蠹Xylosandrus germanus(Blandford)消化道的解剖结构。结果表明,光滑足距小蠹消化道由前肠、中肠和后肠三部分组成。成虫前胃由8个骨化的前胃板组成,呈灯笼状结构。前胃板由板状部和片状部组成,板状部短而简单,片状部甚长,由斜面、咀嚼刷和关闭刚毛组成。胃盲囊着生在中肠近后端,有细管状和囊状2种,成虫分别有1对,幼虫有1对细管状和3~5对囊状。6根马氏管分成2组,1组4根,另一组2根。6根马氏管与后肠肠壁形成隐肾系统。消化道具有1对囊状和1对细管状的胃盲囊可作为光滑足距小蠹成虫的识别特征。     

韭菜迟眼蕈蚊幼虫消化系统的解剖学和组织学

本利用石蜡切片对韭菜迟眼蕈蚊幼虫其消化系统的组织学进行了研究。结果表明,幼虫的消化道无特殊变异,但中肠亚端部的一对胃盲囊长而发达,是消化道的突出特征。中肠和胃盲囊不同部位的细胞学特点有明显差异。根据中肠细胞形状及其分布将中肠分为4个区域,对中肠不同区域的细胞学特点进行了描述。     

普通齿蛉幼虫的消化系统结构和取食分析

研究了普通齿蛉Neoneuromus ignobilis Navás幼虫消化系统的解剖和电镜扫描结构,并结合肠道内食物残渣的成分分析了其取食特性.结果表明,普通齿蛉幼虫消化系统较为简单,无特殊的变异,消化道细长,由前肠、中肠和后肠构成,前后肠较长,分别占体长的42%和47%,中肠最短,仅占总长度的11%.前肠由食道、嗉...     

Radioactive strontium (85Sr) in marking newly hatched pike and success of stocking

Immersion of newly hatched pike fry in an aqueous solution of 1·85 MBq ml⁻¹⁸⁵Sr did not affect their growth or survival over 3 weeks. Cannibal pike fry retained only l.2–3·3% of the ⁸⁵Sr from their labelled prey. Newly hatched ⁸⁵Sr-marked fry stocked into two lakes in 3 years were distinguishable from wild fish 4–6 weeks later. Stocked and wild fry grew equally well, and stocked pike survived best where density of wild pike was highest. There was no evidence of increase in density as a result of Stocking.     

Studies on the activity of the alkaline phosphatase in the midgut of infected silkworm, Bombyx mori L.

The effects of several factors on the activity of alkaline phosphatase (ALKP) in the midgut of the silkworm, Bombyx mori L were studied. The ALKP activity varied greatly among the tested strains. There was positive correlation between ALKP activity and cocoon quality. The ALKP activity of the midgut decreased when the silkworm was infected with cytoplasmic polyhedrosis virus (CPV); whereas, infection with nuclear polyhedrosis virus (NPV) did not affect ALKP activity. This suggests that the pathogenic mechanism of CPV differs from that of NPV. Bacillus thuringiensis caused direct damage to the midgut tissues of the silkworm with a rapid decline in ALKP activity. Activation of ALKP by Mg²⁺ was more evident than the other chemicals. Ascorbic acid, Ca²⁺, citric acid and Cl^– were inhibitory to ALKP in vitro .     

Stocking success of newly hatched pike evaluated by radioactive strontium (85Sr) marking

The stocking of newly hatched pike Esox lucius labelled with radioactive strontium (⁸⁵Sr) and later electrofishing of the same area was found to be a workable tool in assessing the success of pike stockings. ⁸⁵Sr‐labelled individuals constituted 96% of the 0+year pike catch from late summer electrofishing in the stocked littoral areas of the heavily regulated Lokka Reservoir. The density of 0+year pike reached 2·1 individuals 100 m⁻² in the stocked areas in comparison to 0·3 individuals 100 m⁻² in the reference areas. In the three other stocked lakes the proportion of labelled pike in the catch ranged from 0 to 42% in late summer. The results suggest that pike stockings are profitable in filling empty or nearly empty 0+year pike habitats of regulated lakes or other waterbodies, where the natural reproduction of pike has declined due to human activities.     

Effect of digestion on the δ13C and δ15N of fish-gut contents

Gut contents of sand goby Pomatoschistus minutus showed higher C and N isotope values than the food before consumption. This enrichment was more pronounced in the hindgut than in the foregut, probably because of preferential assimilation of ¹²C and ¹⁴N along the gastro-intestinal tract. The results indicated that the shift towards higher values in the alimentary canal occurs in the first 2 h after feeding.     

Development of bile salt-dependent lipase in larval turbot

Pancreatic bile salt-dependent lipase (BSDL) was present with 0·5 μg BSDL larva⁻¹ from hatching in turbot larvae. The enzyme content increased during the yolk sac phase to 1·1 μg BSDL larva⁻¹. This suggests that larval turbot are able to digest lipids from the start of exogenous feeding. The BSDL synthesis was stimulated first by food about 5 days after the onset of first feeding. The content per larva increased exponentially in fed larvae to 20 μg BSDL larva⁻¹ on day 23 after hatching and decreased in starved larvae. In contrast, the specific content decreased during the first feeding phase, meaning that smaller larvae had a higher content of enzyme related to their biomass than did bigger larvae.     

Chernobyl-derived radiocaesium in fish as dependent on water quality and lake morphometry

¹³⁷Cs concentrations in perch Perca fluviatilis , pike Esox lucius and roach Rutilus rutilus obtained from lakes of different size and water quality in an area which received about 10–67 kBq m⁻²¹³⁷Cs, were compared with environmental data. Radiocaesium concentrations were highest in pike, and were about two to three times higher in the pike and perch than in the roach. The largest perch had about four times more ¹³⁷Cs than the smallest ones, but the activities in the pike and roach were independent of fish size. All of the water quality parameters examined correlated with ¹³⁷Cs concentrations in the fish, but the concentrations of ¹³⁷Cs in the bottom sediment did not. ^l37Cs fallout and water retention time in lakes showed a positive correlation with fish ¹³⁷Cs, while the size of the catchment area, phosphorus content of the water, water colour, pH and electrical conductivity showed a negative one. Thus there was more ¹³⁷Cs in the fish from the oligotrophic lakes than from the eutrophic ones, from the less humic lakes than from the more humic ones, from the more acid than from the less acid ones and from the lakes containing less potassium than from those containing more potassium. The depth, area and volume of the lake did not affect radiocaesium in the fish. Regression equations are presented for predicting ¹³⁷Cs in fish on the basis of environmental data. Fallout, total phosphorus and pH together had the highest influence in multiple regression models but were less significant in the roach than in the perch and pike.     

The physiology of digestion in fish larvae

Synopsis The acquisition, digestion, and assimilation of food is critical for the growth and survival of fish larvae; a fish larva either grows or it perishes. Fish larvae are characterized by digestive systems and diets that differ from adults. Larvae undergo a pattern of trophic ontogeny, changing diet with increasing size, and these changes result in differences in digestive requirements. At first feeding, the larval alimentary canal is functional, but is structurally and functionally less complex than that of adults. The larval alimentary canal remains unchanged histologically during the larval period before transformation. During transformation, major changes that result in the development of the adult alimentary canal occur. The ontogeny of the alimentary canal differs in different taxa, and experimental evidence suggests that functional differences exist as well. Assimilation efficiency may be lower in larvae than it is in adult fishes, due to a lack of a morphological and functional stomach in larvae, but the question of improving assimilation efficiencies during larval development before transformation remains unresolved.     

狭胸天牛成虫和幼虫的消化道研究

研究了狭胸天牛成虫和幼虫消化道形态。成虫消化道细长,嗉囊长囊状,中肠前段具极少的稀疏瘤状小突起。幼虫消化道相当长,前肠细短,中肠很长,前中肠粗短而膨大,中肠表面无小盲囊。     

The population biology of pike, Esox lucius L., in two gravel pit lakes, with special reference to early life history

The population biology of pike in two gravel pit lakes of contrasting habitat type were studied. The density of pike (1 + and over) in November 1987 in the Main Lake was 7.7 fish ha⁻¹ (19 kg ha⁻¹) and in St Peter's was 71 fish ha'(53 kg ha⁻¹). The age distribution showed that recruitment was consistent in St Peter's but variable in the Main Lake. The main factor causing this difference in recruitment is abundance of aquatic vegetation. Survival up to November 1987 of 0-group pike in the Main Lake was 0.00175% from potential egg deposition, producing 6.6 fish ha⁻¹ (0.83 kg ha⁻¹). In St Peter's survival was 0.00315%, producing 23 fish ha⁻¹ (3.04 kg ha ¹).     

Pharynx and intestine

The alimentary canal of polychaetes consists of a foregut, midgut, and hindgut. The alimentary canal shows different specializations even in homonomously segmented polychaetes. The foregut gives rise to the buccal cavity, pharnyx and oesophagus, the midgut may be divided into a stomach and the intestine proper. Since polychaetes use a wide spectrum of food sources, structures involved in feeding vary as well and show numerous specializations. In the foregut these specializations may be classified as one of the following types: dorsolateral folds, ventral pharynx, axial muscular pharynx, axial non-muscular proboscis and dorsal pharynx. The latter, typical of oligochaetous Clitellata, occurs rarely in polychaetes. The structure, evolution and phylogenetic importance of these different types are described and discussed. Axial muscular and ventral pharynges may be armed with jaws, sclerotized parts of the pharyngeal cuticle. Terminology, structure, occurrence and development of the jaws are briefly reviewed. Special attention has been paid to the jaws of Eunicida including extinct and extant forms. Conflicting theories about the evolution of the jaws in Eunicida are discussed. The epithelia of the intestine may form a pseudostratified epithelium composed of glandular cells, absorptive cells and ciliated cells or only one cell type having similar functions. A conspicuous feature in the intestine of certain polychaetes is the occurrence of unicellular tubular structures, called enteronephridia. So far these enteronephridia are only known in a few meiofauna species.     

Adrenergic responses and the Root effect in erythrocytes of freshwater fish

The effects of adrenergic-stimulation upon the oxygen-binding capacity of fish erythrocytes have been investigated. The oxygen capacity of rainbow trout, Oncorhynchus mykiss (Walbaum), erythrocytes was lowered by 44% on extracellular acidification (the so-called 'Root effect'). Addition of isoproterenol at 20° Ccaused an acid shift of the curve relating oxygen capacity to pH₀ by approximately 0.2 pH units, a value which was similar to the change in intracellular pH caused by adrenergic stimulation (Cossins & Kilbey Journal of Experimental Biology , 148 , 303–312, 1990). Moreover, when plotted as a function of pH_i, the curves for control and adrenalinstimulated erythrocytes were superimposable suggesting that the adrenergic shift in the Root curve was a result of the change in pH_i caused by activation of the adrenergic Na⁺/H⁺ exchanger.
A similarly large adrenergic shift in the Root curve was observed for pike, Esox lucius L., erythrocytes, though not for erythrocytes of carp, Cyprinus carpio L., and tench, Tinea tinea (L.). The pH for the mid-point of the Root effect in pike erythrocytes was distinctly more acid than for trout, but in both cases corresponded closely with the optimal pH for the adrenergic Na⁺/H⁺ exchange mechanism. This suggests a link between the functional characteristics of the exchanger and the oxygen-binding properties of haemoglobin.     

The relationship between temperature and the size and age of larvae and peri‐metamorphic stages of Pleuronectes flesus

Habitat use of 0+ year pike Esox lucius (mean 20–31 mm L _T) was evaluated in artificial ponds (surface area = 16 m²) in relation to water transparencies (low and high), habitat complexity (low and high), food availability (zooplankton) and cannibalism (mortality in the ponds). Pike could choose freely between a structured area, an open water area and a structure and open water interface area. Habitat use shifted towards the structured habitat type in the presence of high habitat complexity and low water transparency. Both findings could be explained as a consequence of territorial behaviour. When cannibalism was intense, the proportions of pike using the structures were reduced and the largest pike, and hence the potential cannibals, were found inside the structures. Since the smallest pike were constrained to the unsheltered, and hence probably more hazardous, habitat outside the structures, this study suggests that mortality due to intra‐cohort cannibalism may occur in an indirect as well as a direct way.     

美国白蛾幼虫消化道形态和超微结构观察

美国白蛾Hyphantria cunea Drury是我国重要的林业检疫性害虫之一,世界范围内寄主多达600余种,对我国林业生产和生态环境建设造成了巨大损失。明确美国白蛾幼虫消化道各部分的形态结构,可为进一步研究其幼虫的食性及消化机能奠定基础。利用光学显微镜、扫描电子显微镜与透射电子显微镜观察了美国白蛾6龄幼虫消化道形态及超微结构。美国白蛾幼虫的消化道由前肠、中肠、后肠组成。前肠是消化道最长的部分,占整个消化道的54.27%,包括咽、食道、嗉囊、前胃四部分;中肠较短,占整个消化道的21.28%,内部具围食膜;后肠由幽门、回肠、结肠和直肠组成,幽门由幽门锥和幽门瓣组成。马氏管共6条,丝腺2条。美国白蛾幼虫消化道总体结构大部分鳞翅目消化道结构相似,但是其前肠在长度上发生了较大的变异,本文进一步讨论了美国白蛾幼虫消化道结构与其食性及耐饥饿能力等的相关性。