Scale regeneration and calcification in goldfish <Emphasis Type="Italic">Carassius auratus</Emphasis>: quantitative and morphological processes

The time-course changes in calcium and phosphorus contents, dry weight, and area during scale regeneration in the goldfish, Carassius auratus L. were quantified. Histological observations were then conducted to understand the mutual relationship between the quantitative and morphological processes of scale regeneration. The quantitative study revealed that regenerating scales grow most rapidly in area during the first 5 days of regeneration. The gradual decrease in the area growth rate coupled with the continuous linear weight growth over the period of 5–28 days suggests a shift in growth priority from area growth to the apposition, of the basal plate. Calcium and phosphorus deposition proceeded almost linearly during scale regeneration. Calcification of the bony layer preceded that of the basal plate and, after 14 days of regeneration, calcification of the basal plate started and gradually progressed. On day 28, recovery of calcium and phosphorus contents in the regenerating scales were approximatley 72% of ontogenetic scales, which is lower than the rates of area and weight regeneration (104 and 85%, respectively). Late initiation and slow progress of calcification in the basal plate is suggested to be responsible for the slow regeneration in calcium and phosphorus contents.     

Post-molt processes of cuticle formation and calcification in the Japanese mitten crab <Emphasis Type="Italic">Eriocheir japonicus</Emphasis>

This study examines the following in the Japanese mitten crab: (1) the structure of the exoskeleton with special reference to its calcification; (2) the progression of post-molt cuticle formation and calcification. In the crab, the structure and calcification state of the exoskeleton at the molt and during the inter-molt stage were similar to those of other crustaceans. During the inter-molt, the exoskeleton consisted of four cuticle layers; the outermost epicuticle, the exocuticle, the endocuticle and the innermost membrane layer. Intense calcification was observed in the exo- and endocuticle. At the molt, the synthesis of the epi- and exocuticle was already complete, and the addition of the endocuticle began after the molt. Calcification of the exocuticle initiated soon after the molt, but there was a delay between endocuticle matrix synthesis and calcification. Histology showed that the process of calcification was similar to that in other crustaceans. However, calcium concentrations within the exoskeleton continued to increase and never reached the levels of the inter-molt stage at the end of the experiment. This suggests that the Japanese mitten crab is relatively slow to calcify compared to other crustaceans.     

Sodium fluoride influences calcium metabolism resulting from the suppression of osteoclasts in the scales of nibbler fish <Emphasis Type="Italic">Girella punctata</Emphasis>

The influence of sodium fluoride (NaF) on calcium metabolism was examined in nibbler fish (marine teleosts). Two days after the administration of NaF (5 μg/g of body weight) (around 10^?4 M in fish), we showed that plasma calcium levels significantly decreased in NaF-treated nibbler fish. In addition, we detected fluoride in the treated scales by use of a scanning electron microscope with an energy-dispersive X-ray microanalysis, indicating that NaF directly affects their scales. Therefore, the influence of NaF on osteoblasts and osteoclasts in the scales was examined. In the scales of NaF-injected nibbler fish, tartrate-resistant acid phosphatase (TRAP) (osteoclastic marker enzyme) decreased, although alkaline phosphatase (osteoblastic marker enzyme) was activated. To confirm the effect of NaF on osteoclasts, furthermore, the mRNA expressions of osteoclastic markers (matrix metalloproteinase-9 and TRAP) were decreased significantly 2 days after incubation. In barred knifejaws, plasma calcium levels decreased as they did in nibbler fish. Therefore, NaF functions in both osteoblasts and osteoclasts and then influences calcium metabolism in marine fish. In the marine environment, high levels of fluoride (1.2–1.5 mg F^?/l) (around 10^?5–10^?4 M) are present in seawater. It is probable that teleosts living in seawater efficiently use fluoride to regulate their blood calcium levels.     

Effects of etidronate on calcification of scales and ribs in the goldfish, Carassius auratus

Effects of etidronate on the calcification of scales and ribs were investigated in goldfish. Daily intraperitoneal injections of etidronate at doses of 1 and 10 mgP/kg body weight for 2 weeks inhibited calcification of ontogenic scales and ribs without affecting the accretion of organic matrices. Removal of some scales induced their regeneration within the two-week period. Their newly formed organic matrix was fully uncalcified in fish treated with 10 mgP/kg, whereas in those treated with 1 mgP/kg, the regenerating scales were only partially calcified. Daily administration of etidronate 10 mgP/kg resulted in an increase of body weight. These results suggested that the inhibitory effect of etidronate on the calcification of osseous tissues in mammals can be expected also on comparable tissues in fishes. An appropriate dose of etidronate that inhibits hard tissue calcification but not affects the body growth in fish seemed to exist between 1 and 10 mgP/kg.     

Effects of Calcium-Binding Peptide from Tilapia Scale Protein Hydrolysates on Calcium Absorption in Caco-2 Cells

ABSTRACT

Fish scales are usually discarded as an industrial solid waste. In this study the fish scale protein was recovered and employed to prepare protein hydrolysates using commercial proteases. The hydrolysates were further separated into four peptide fractions (F1, F2, F3, and F4) by Sephadex G-15. Among the fractions, the F3 fraction, with the highest calcium-binding activity, was further investigated to enhance calcium uptake in Caco-2 cells. The results showed calcium uptake from F3-Ca by Caco-2 cells after 2 h of incubation was significantly higher than those of CaCl₂ and tilapia scale protein hydrolysates (TSPH), respectively, and was similar to that of casein phosphopeptide (CPP). Therefore, the F3 fraction improved Ca uptake versus the CPP samples and can be employed as an alternative to CPP in the manufacture of functional foods.     

Dynamics of scale regeneration in seawater- and brackish water-acclimated sea bass, Dicentrarchus labrax

Scale loss is a common occurrence in both wild fish and those in aquaculture production systems, and regeneration of scales has been described in several freshwater species. Relatively little information exists about this process in marine fish, and in the present study, the chronology of scale regeneration was characterized in juvenile sea bass Dicentrarchus labrax, maintained in full seawater (SW; 36 ‰, 11.2 mM Ca²⁺) or brackish water (BW; 3.5 ‰, 1.1 mM Ca²⁺). Despite the significant differences in plasma osmolality, plasma calcium (Ca) and phosphorus (P) were similar between SW and BW. Removal of scales (2.25 cm²) did not modify plasma osmolality but a significant reduction in plasma Ca occurred in sea bass in BW during early phases of scale regeneration. Scale Ca and P contents changed during regeneration in SW and BW fish, and in fully regenerated scales, their concentration was comparable to ontogenic scales which had a Ca/P ratio around 1.0. Regenerating scales were first visible at 3 days after removal, and by 6 days, the descaled area was covered with new scales in both SW and BW fish. From this stage onwards, while scale area and mass rose gradually, a rapid accretion of calcium crystals was observed over the basal plate, especially in SW, and Ca and P content per scale increased at a very high rate, decreasing only at the later stages, and between 21 and 30 days the newly formed scales had already ontogenic-like morphometric features. Scale tartrate-resistant acid phosphatase (TRAP) or alkaline phosphatase (ALP) activity was initially similar in SW and BW. However, during regeneration, TRAP was significantly higher in scales of sea bass in SW compared to those in BW where ALP predominated; these differences persisted at 30 days.     

草鱼鱼鳞对刚果红的吸附性能及其机理

以草鱼鱼鳞为原料制备生物吸附剂,比较了该鱼鳞吸附剂对几种不同化学染料的吸附效果,研究了其对刚果红的最佳吸附条件及相关影响因素,并通过吸附动力学和吸附热力学分析以及吸附前后的红外光谱分析,初步探讨了鱼鳞吸附剂对刚果红的吸附机理。实验结果表明,鱼鳞吸附剂对含有磺酸根基团的染料具有良好的吸附能力,其对不同染料的吸附效果依次为:刚果红＞胭脂红＞亮蓝＞日落黄＞亚甲基蓝;在室温条件下,鱼鳞吸附剂吸附刚果红的最佳吸附条件为:吸附剂用量0.2 g/L、体系pH 7.0、刚果红初始浓度为14 μg/mL;吸附热力学和动力学分析表明,鱼鳞吸附剂对刚果红的吸附是一种以不可逆方式自发进行的吸热过程,准二级动力学模型可以较好地反映这种动态吸附行为。红外光谱分析表明,鱼鳞吸附剂中参与吸附刚果红的功能性官能团主要包括氨基、羧基、磷酸根和碳酸根等,其分别归属于鱼鳞中的蛋白质和羟基磷灰石类成分。     

In vivo calcitropic effect of some vitamin D compounds in the marine Antarctic teleost,Pagothenia bernacchii

The Antarctic notothenioid, Pagothenia bernacchii, were found to have plasma total and free calcium levels, plasma inorganic phosphate and whole body calcium efflux rates which were similar to those seen in other teleosts. But total bone calcium was lower than reported for other teleosts. A single injection of vitamin D₃ (5 ng g^–1 fish) increased plasma total and plasma free calcium and these increases were associated with an increase in whole body calcium efflux and bone calcification. Conversely, the same treatment with 1,25-(OH)₂-D₃ reduced plasma free calcium. This seco-steroid also increased the specific activity of ⁴⁵Ca in bone at 40h post-injection but did not significantly effect total bone calcium, plasma total calcium or whole body calcium efflux. 25-OH-D₃ at the same dose had no effect on any of the parameters tested and none of the seco-steroids tested had any effect on plasma total inorganic phosphate. These data show that both D₃ and 1,25-(OH)₃-D₃ can have calcitropic effects in this marine teleost and that these two forms of vitamin D can exert different effects within the same species.     

Localization of Zn-binding protein in the digestive tract tissue of common carp

ABSTRACT: The concentrations of Zn and sulfhydryl (SH) groups in the digestive tract tissue of common carp and some aquatic animals were studied. It was found that Zn and bound SH groups could be used as indicators for detecting the Zn-binding protein in the digestive tract tissue of common carp. The digestive tract tissue of the fish underwent subcellular fractionation, and it was found that the nuclei/cell debris fraction contained most of the DNA (85%), Na⁺/K⁺-ATPase (82%), organic phosphate (90%) and the Zn-binding protein (79%), but only part of the 5'-nucletidase and alkaline phosphatase (<23%). The nuclei/cell debris fraction of the digestive tract tissue of common carp was treated with either collagenase type I or type IV, and subfractionated by sucrose density centrifugation. It was found that treatment with collagenase type IV could release more than 50% of the Zn-binding protein, Na⁺/K⁺-ATPase and organic phosphate from collagen. Sections of digestive tract tissue of common carp were stained for Zn. It was observed that Zn can be found mainly on the edge of the epithelial layer, and everywhere in the 'membrane-like' portion of the submucosal and muscular layers. It is proposed that most of the Zn-binding protein in the digestive tract tissue of common carp is located on the basolateral plasma membranes of the epithelial cells and on the surrounding muscle cells that are attached to the collagen type IV of basal laminae.     

酶法提取4种淡水鱼鱼鳞胶原蛋白的研究

对4种常见淡水鱼鱼鳞的基本成分和氨基酸组成进行了测定,研究了酶解鱼鳞制备水解胶原蛋白的工艺,并采取正交试验对水解条件进行了优化。试验结果表明,淡水鱼鳞主要由蛋白质和灰分组成,粗蛋白含量高达55%以上;氨基酸组成显示淡水鱼鳞羟脯氨酸含量丰富,是制备水解胶原蛋白的良好原料。正交试验结果表明,55℃、E/S3%、酶解2h、料液比1∶10(即底物质量浓度为100g/L)时水解效果最好,此时,水解产物分子量较小,且分布集中。     

Tartrate resistant acid phosphatase as a marker for scale resorption in rainbow trout,Oncorhynchus mykiss: effects of estradiol-17β treatment and refeeding

In teleosts, a considerable part of the body calcium is found in the scales. Associated with the scales are osteoblasts and osteoclasts, and during periods of high calcium demand such as during sexual maturation or starvation, the scales can be resorbed and thereby act as an internal calcium reservoir. In mammalian bone tissue, the activity of an acid phosphatase (ACP) isoenzyme, tartrate resistant acid phosphatase (TRACP), can be used as a marker for osteoclastic activity. In the present study, an evaluation of TRACP as a marker for osteoclastic activity in teleost scales has been performed. ACP and TRACP was histologically localized at resorption sites around the edge of the scales as well as at resorption holes in the scales. The optimal conditions for biochemical measurements of ACP and TRACP activity were found to be pH 5.3, 10 mM paranitrophenylphosphate, incubated for 30 min at room temperature, and 10 mM tartrate added when required. Using TRACP as a marker, estradiol-17 (E₂) was found to increase the proportion of scales being resorbed, as well as the number and size of resorption sites per scale. Also, the scales of E₂-treated fish showed weaker staining for calcium. Together, the obtained data indicate that estradiol-17 induces osteoclastic activity in teleost scales, resulting in increased resorption of the scales. A period of refeeding following a period of starvation did not have detectable effects on the scale osteoclastic activity and scale resorption.     

Prostanoids-induced dispersion in the melanophores of a carp Labeo rohita (Ham.)

Effects of three prostaglandins (i.e., prostanoids) and one of its precursors, arachidonic acid, were examined on the melanophores of the fish Labeo rohita (Ham.). PGE₁, PGE₂, PGF_2α and arachidonic acid elicit a concentration-related dispersion in the fish melanophores. In vitro analysis of melanophores was performed through incubation of the isolated fish scales in different agonists and antagonists solutions. Dispersal effect of prostanoids may be mediated directly through the typical receptors or indirectly through release of neurotransmitter substance(s) from the melanophore nerve endings. Denervation of fish melanophores rendered them insensitive to prostanoid (PGF_2α). Propranolol and verapamil completely inhibited the dispersal effects of PGF_2α; theophylline and indomethacine blocked the effects of higher concentrations of PGF_2α. During dispersing influence of PGF_2α, a free flux of Ca²⁺ ions was required and the indirectly released substance(s) from melanophore nerve endings would be the catecholamines of adrenergic and purinergic in nature.     

Effects of life‐history traits on stream fish abundances across spatial scales

Identifying cross‐scale patterns of ecological processes is imperative, especially in hierarchically structured riverine ecosystems. The role of abiotic factors in determining cross‐scale spatial structure of stream fish populations and communities is well studied, but less is known about how species traits drive cross‐scale patterns. We investigated the role of species traits for explaining autocorrelation of stream fish abundance at spatial scales ranging from local stream reaches to major basins. We calculated intraclass correlation coefficients (ICCs) representing abundance autocorrelation within species (N = 47) at each of five spatial scales. A hierarchical Bayesian regression then modelled ICCs against spatial scale with the resulting regression coefficients modelled as functions of species traits. Finally, we ordinated the scale‐by‐species ICC matrix to calculate an overall metric describing species whose abundances were autocorrelated along a gradient of large to small scales, and modelled this metric as a function of species traits. Abundances of most species were autocorrelated at smaller spatial scales. Maximum fecundity had a significant positive relationship with abundance patterns across spatial scales. Species habitat affinities and body forms were significantly associated with overall abundance patterns across spatial scales: populations of upland/lotic‐affiliated species adapted to streams with high flow correlated at small (≤10 km²) spatial scales. Lowland/lacustrine species with laterally compressed bodies showed little correlation across scales. The appropriate spatial scale for modelling abundance is determined not only by exogenous (e.g. environmental) factors, but also endogenous factors, like traits. Careful consideration of traits and life history will aid researchers in designing more effective and efficient surveys and analyses.     

Fish assemblages in Atlantic Forest streams: the relative influence of local and catchment environments on taxonomic and functional species

Streams are under environmental pressures acting at different scales that influence the ecological organisation of their fish assemblages. However, the relative influence of the different scale‐related variables on assemblage composition and function is poorly understood. We evaluated the importance of local‐ and catchment‐scale environmental variables, as well as the spatial structure of the sampling sites, in shaping fish assemblages in Atlantic Forest streams. Local‐scale variables were those measured at the sampling sites, describing the local habitat conditions (e.g. depth, substrate type, altitude). Catchment‐scale variables were those integrating the upstream landscape of the sampling sites (e.g. catchment land use). Spatial distances were calculated from watercourse distance using principal coordinates of neighbour matrices. Altogether, 28 local and seven catchment variables were initially subjected to two processes of eliminating co‐linearity. Redundancy analysis was applied to the three matrices (spatial, local and catchment) to quantify the variance in the structure of the fish assemblages explained by each matrix. Local variables explained more variability in both taxonomic and functional assemblage structure, than catchment and spatial variables. Local variables also changed along the longitudinal gradient, which consequently influenced fish assemblage structure. This pattern was also influenced by anthropogenic alteration and non‐native species, which were more abundant in downstream sites. These results highlight the need to assess Atlantic Forest streams under different environmental scales, especially through the use of quantitative local‐scale metrics, and to consider the effects of longitudinal patterns in structuring fish assemblages when developing and implementing monitoring programmes, impact studies and conservation plans.     

Shipping canals on the downstream migration route of European eel (Anguilla anguilla): Opportunity or bottleneck?

Migrating fish species are worldwide in decline due to several global changes and threats. Among these causes are man‐made structures blocking their freshwater migration routes. Shipping canals with navigation locks play a dual role in this. These canals can serve as an important migration route, offering a short cut between freshwater and the sea. In contrast, the navigation locks may act as barriers to migration, causing delays and migration failures. To better understand these issues for downstream migrating fish, we studied the behaviour of European eels (Anguilla anguilla) in the Albert Canal at two scales. The mid‐scale contained a 27‐km canal pound confined by two navigation lock complexes, in which we released and tracked 86 silver eels. The small scale was a 200 × 150 m area just in front of the most downstream complex of the canal pound, where we analysed the behaviour of 33 eels in relation to the flow field resulting from a computational fluid dynamics (CFD) model. This paper discusses the factors influencing fish behaviour, and the relation between these behaviours on both scales. On the mid‐scale, migration efficiency resulted from a combination of intrinsic behaviour and flow in the canal pound. Also on the small scale, intrinsic behaviour influenced the success to pass the navigation lock. Increasing the flow would create more attraction and passage opportunities and hence facilitate migration through shipping canals, but only if this flow guides the fish through safe passage routes.     

海洋酸化对栉孔扇贝钙化、呼吸以及能量代谢的影响

通过Alkalinity anomaly technique测定了栉孔扇贝Chlamys farreri在不同酸度条件下的钙化率和呼吸率,发现栉孔扇贝的钙化和呼吸活动受酸化影响显著,均随着酸化的加剧出现了明显下降。当pH降低到7.9时,栉孔扇贝的钙化率将会下降33%左右;当pH降到7.3左右时,栉孔扇贝的钙化率将趋近于0,栉孔扇贝无法产生贝壳,而此时栉孔扇贝碳呼吸率(RC)与耗氧率(RO)也分别下降了14%和11%。随着酸化的加剧,栉孔扇贝的能量代谢方式也会发生改变。这些变化都可能影响到栉孔扇贝的生存。     

Towards a universal scale to assess sexual maturation and related life history traits in oviparous teleost fishes

The literature presents a confusing number of macroscopic maturation scales for fish gonads, varying from over-simplified scales comprising three to four stages to highly specific and relatively complicated nine-stage scales. The estimation of some important life history traits are dependent on a correct assessment and use of the gonadal maturation scales, and frequent mistakes have been made in many studies. The goal of this report is to provide a synthetic, relatively simple, yet precise maturation scale that works for most oviparous teleost fishes. The synthetic scale proposed here is based on the correspondence between key physiological and cytological processes of gamete development and corresponding modifications observed at the macroscopic level. It is based on previous and ongoing studies of several fish species pertaining to some of the most important African and Neotropical taxa, including Characiformes, Siluriformes, Osteoglossiformes and Perciformes. This scale should allow for standardized protocols of field studies and improve intra- and inter-specific comparisons of life history traits. Guidelines on the correct use of this scale to estimate these life history traits are provided.     

Effect of body weight on the chemical composition and collagen content of snakehead fish <Emphasis Type="Italic">Channa striata</Emphasis> skin

Snakehead fish (Channa striata) skin is a fishery by-product that has the potential for further processing because it contains a high amount of organic matter. This study investigates the effect of body weight on the chemical composition and collagen content of snakehead fish skin. This study used fresh snakehead fish of either gender. Their body weights were divided into three groups: small, medium, and large size. The characteristics of snakehead fish skin included proximate composition, amino acid content, collagen content, microstructure, and minerals. Snakehead fish skin from fish of different body weights indicated that the moisture content and ash tended to decrease, the protein content was relatively stable, and the lipid content tended to increase with increasing body weight. Glycine and proline comprised the highest percentages of amino acids at all levels of body weight, and the presence of hydroxyproline showed that snakehead fish skin was the source of collagen. There was no significant difference in body weight observed on collagen protein content of the skin. This study on the microstructure and mineral content of snakehead fish skin can be used as supporting information to promote the potential utility and economic value of the skin.     

Association of zinc with connective tissue in the digestive tract of common carp

ABSTRACT:   Zinc (Zn) concentration in the digestive tract of common carp is always >10 times higher than most animal tissues. In a previous paper, it was reported that this high Zn came from a 43 kDa Zn-binding membrane protein. In this present study it was further found that in the digestive tract of common carp, Zn content was closely associated with the amounts of extracellular macromolecules. The higher the Zn content, the more there is of collagen and glycosaminoglycans. An indirect immunoperoxidase staining method using antibody against the 43 kDa Zn-binding protein, or the fibroblast marker (Thy 1.1 protein) was applied to the sections of digestive tract of fish. It was found that the Zn-binding protein in the digestive tract of common carp is mainly located in the connective tissue of its lamina propria and submucosal layer. Connective tissue cells, probably fibroblasts, hold the 43 kDa Zn-binding protein. In the common carp Zn might be bound to the external side of the fibroblast. The present finding may have a significant meaning on extending the studies of Zn in biology to the field of Zn with extracellular matrix.