Search

To investigate the alkali resistance of the hybrid of Leuciscus and its parent Leuciscus waleckii （female parent） and Leuciscus idus （male parent） of the Irtysh River in Xinjiang, the alkalinity stress experiment of 50 mmol/L NaHCO3 was carried out on three experimental fish for 7 days. Several physiological indexes and corresponding gene expressions involving osmotic pressure regulation and ammonia metabolism and significantly related to alkali resistance were compared and studied. The results showed that the Na+/K+ ATPase （NKA） activity and gene expression （ATPase α1-like and ATPase α3） of the gill tissues of the female parent with strong alkali resistance were higher than those of hybrids, and significantly higher than those of the male parent. The serum alkaline phosphatase （AKP） activity and the gene expression amount （alpl） of gill tissue were significantly lower than those of the other two fish, indicating that the female parent may regulate NKA enzyme activity through AKP dephosphorylation and participate in osmotic pressure regulation under high alkaline stress. The detection of ammonia metabolism related indexes showed that the blood ammonia （Amon） and urea nitrogen （BUN） contents of the female parent were extremely significantly lower than those of the other two fish, while the serum glutamate dehydrogenase （GDH） and glutamine synthetase （GS）, as well as the expression of related genes in the gill tissue （glud, glul, Rhbg and Rhcg1） were mostly higher than those of hybrids, and significantly higher than those of the male parent, indicating that the female parent consumed ammonia in the body by synthesizing ammonia intermediate metabolites and increasing the activity of ammonia transporters. In summary, these physiological indexes were significantly related to the female parent's strong alkali resistance, and were well inherited to its hybrid offspring. The results of this study provide a theoretical basis for the comprehensive evaluation of the alkali resistance of fish, and lay a working foundation for the selection and breeding of new varieties of alkali resistance and the declaration of improved varieties of Leuciscus. [ABSTRACT FROM AUTHOR]

Abstract: Differential use of habitat and prey resources is an important mechanism that may allow coexistence of sympatric species. Unlike interactions between smaller cyprinid and percid fishes, the resource use by coexisting predatory asp (Leuciscus aspius) and pikeperch (Sander lucioperca) is relatively unknown. Here, gut content and stable isotope analyses were used to study ontogenetic dietary shifts and interspecific trophic niche overlap between asp and pikeperch coexisting in two reservoirs. The hypothesis that both species show an ontogenetic dietary shift from small invertebrates to large fish prey, but at the same time use different prey resources to reduce potential competitive interactions, was validated. The isotopic niches of the two predators showed no, or only a moderate, degree of overlap (0%–65%). The ontogenetic changes in the degree of interspecific isotopic niche overlap were different in the two reservoirs, suggesting that trophic segregation can be dynamic and variable among systems. Gut contents revealed that small (<100 mm standard length) asp consumed mostly terrestrial invertebrates and emerged aquatic insects, whereas small pikeperch foraged on zooplankton, larval and pupal stages of aquatic insects and fish. Larger individuals (>100 mm) of both species were predominantly piscivorous, with asp consuming more cyprinid prey and pikeperch more percid prey. Coexisting asp and pikeperch populations are able to utilise different prey resources, thereby reducing potential negative competitive interactions. [ABSTRACT FROM AUTHOR]

This study investigated how the inhibition of certain enzymes present in ide sperm influences sperm motility and the percentage of fertilised eggs. The enzymes studied were acid phosphatase (AcP), β- N -acetylglucosaminidase (β-NAGase) and lactate dehydrogenase (LDH). None of the inhibitors affected ide sperm motility parameters. The addition of gossypol (a LDH inhibitor) caused a considerable increase in the percentage of fertilised eggs (92–95% compared to 63% in the control). The inhibition of AcP caused a considerable decrease in fertility rate – at the highest inhibitor dose, the percentage of fertilised eggs decreased to 26%. A similar effect was seen after the addition of acetamide (a β-NAGase inhibitor), but in this case the highest dose caused complete inhibition of fertilisation. The results presented here indicate the importance of AcP and β-NAGase in the process of ide fertilisation. [ABSTRACT FROM AUTHOR]

A total of 128 fish samples including 70 Cyprinus carpio Linnaeus, 1758, 10 Leuciscus vorax (Heckel, 1843), 40 Oreochromis aureus (Steindachner, 1864) and eight Planiliza abu (Heckel, 1843) were collected during the period from November 2016 to May 2017. Seven different localities (floating cages, earthen ponds and natural water) in Basrah were investigated. Among some detected fish diseases, whirling disease symptoms was reported for the first time in Iraq in April 2017, from two C. carpio cultured in earthen fish ponds of Marine Science Centre, University of Basrah. The infested fish were dwarfed, with abnormal big head and small body. Grossly signs of the diseases represent fins and tail deformities in addition to open ulcers and losing of scales, and necrosis of skin and muscles. Internally, fish suffered of muscles ecchymosis and vertebral deformities. Histological sections revealed that the spinal cord had healthy structure. [ABSTRACT FROM AUTHOR]

A telemetry study analysing the diel and seasonal behaviour of asp was performed weekly in the Elbe River, Czech Republic, over 12 months. Asp diel movements and home range size varied across seasons, reaching maxima in summer and autumn with diurnal and/or crepuscular peaks of activity. On the contrary, no peaks of activity occurred during spring and winter, when the diel movements were low and the home range was small. Asp occurred predominantly within their home range. The probability of displaying migratory behaviour peaked during spring spawning and autumn wintering migrations (both triggered by temperatures from 4 to 8 °C). Three spawning grounds were detected within the studied river stretch. Most of the spawners utilised the first suitable spawning ground below the weir, which was not passed by any of the tagged specimens. Our results suggest a strong impact of weirs, even equipped with modern fish passes, on migratory behaviour and thus population dynamics of river-dwelling asp. [ABSTRACT FROM AUTHOR]

We explored whether fin clips and scales can be used as potential non-lethal alternatives to muscle tissue for examining the isotopic composition of asp Leuciscus aspius, a locally threatened freshwater species. Dorsal fin clips, scales and muscle plugs were collected from two asp populations and subsequently analysed for nitrogen and carbon stable isotopes. Both fins and scales were consistently depleted in N and enriched in C relative to muscle. A linear regression found that the isotope values in asp fins and scales were significantly related to those in the muscle tissue. These results indicate that fins and scales have the potential to be a substitute for muscle in stable isotope studies of asp, thus providing a non-destructive sampling method for this species. Nevertheless, to determine reliable conversion factors between tissues, a subset of individuals covering a sufficiently wide range of body sizes may need to be sacrificed for any given population. [ABSTRACT FROM AUTHOR]

Contents Seminal plasma ( SP) and ovarian fluid ( OF) plays an important role as storage media to prevent the activation of gametes both in vivo and under artificial conditions. The objectives of this study were to quantify gamete biochemistry and explore correlations among quantitative characteristics of SP, OF and sperm performance traits of Ide Leuciscus idus and Northern pike Esox lucius. Generally, Na+, K+ and Cl− were found to be the most dominating ions, although concentrations of K+ were higher in SP, while Na+ and Cl− concentrations were higher in OF for both species. Several significant correlations among the biochemical properties such as total protein, glucose, osmolality, cholesterol, K+, Ca2+, Cl− and Mg2+ were observed for SP and OF. Total protein content of Ide SP was positively correlated with sperm activity traits ( r ≥ .89, p ≤ .05), while K+ concentration was negatively correlated with sperm traits ( r ≥ −.89, p ≤ .05). Moreover, Ca2+ concentration in Northern pike SP was positively correlated with the percentage of sperm motility ( r = . 98, p < .01). In conclusion, these results can be used to better understand the biochemistry of SP and OF, improve methods for short- and long-term storage of gametes and standardize fertilization protocols. [ABSTRACT FROM AUTHOR]

Anthropogenic river fragmentation has the potential to alter fish population structure and diversity, but it can be difficult to infer whether observed effects reflect the obstruction of fish movement or population responses to altered flow regimes or habitat structure concomitant with fragmentation. We addressed the influence of habitat fragmentation on the European Chub (Squalius cephalus), a large-bodied fish with strong swimming ability that is a ubiquitous habitat generalist that occurs at high densities in lentic and lotic habitats. European Chub populations have never been stocked and are little affected by habitat alterations. Thus, they are good sentinels for the effects of fragmentation per se. We used microsatellite genotyping of 1726 fish from 38 sites to compare the genetic structure and diversity of European Chub populations from 3 Swiss midland rivers that are unequally affected by man-made fragmentation. The Thur is unfragmented, the adjacent Glatt is strongly fragmented by tall barriers, and the Broye is fragmented by a large number of low barriers that are individually traversable. European Chub from the Thur possessed the highest allelic diversity overall and showed no significant isolation-by-distance and only a weak nonsignificant upstream decline in genetic diversity. European Chub from the Glatt were less genetically diverse and showed significant isolation-by-distance that was explicable by existing barriers and the presence of a lake in the system and a steep upstream decline of allelic diversity. European Chub from the Broye showed no genetic substructure, suggesting that barriers of low height, even when numerous, had little effect on population connectivity. The detectable effects of anthropogenic fragmentation of rivers on a highly mobile fish like the European Chub suggests that less mobile species, such as habitat specialists or small benthic species, are potentially more vulnerable to isolation. [ABSTRACT FROM AUTHOR]

Standardization of fertilization protocols is crucial for improving reproductive techniques for externally fertilizing fish in captive breeding. Therefore, the objectives of this study were to determine the effects of preincubation of eggs and activation medium on the percentage of eyed embryos for ide ( Leuciscus idus ). Pooled eggs from five females were preincubated in three different activating media for 0, 30, 60, 90, and 120 seconds and then fertilized by pooled sperm from five males. At the eyed-egg stage, the percentage of viable embryos was later calculated. Results showed that preincubation time was significant for the freshwater activation medium (P < 0.001), such that the percentage of eyed embryos declined across the preincubation time gradient. Additionally, there was an effect on the percentage of eyed embryos when eggs were incubated with Woynarovich solution (P < 0.001), such that a decline was detected at 90 seconds, whereas no effect was detected for the saline water medium. Activating medium had a significant effect on the percentage of eyed embryos for each preincubation time (P < 0.05). More precisely, freshwater produced the lowest percentage of eyed embryos at all preincubation times (ranged from 1.9% at 120 seconds to 43.6% at 0 seconds), whereas saline water and Woynarovich solution produced the highest percentage of eyed embryos at 0 seconds and 30 seconds before incubation. Woynarovich solution produced the highest percentage of eyed embryos at 60 seconds (65.26%), whereas saline water produced the highest percentage at 90 seconds (68.37%). No difference was detected between saline water and Woynarovich solution at 120 seconds. Examination of sperm traits showed no impact of activating medium on computer assisted sperm analysis parameters. Together, these results suggest that saline water or Woynarovich solution improve fertilization rate in ide during IVF; thus, these media are useful for standardizing fertilization protocols and controlled reproduction for this species. [ABSTRACT FROM AUTHOR]

The proximate composition of male and female Leuciscus lepidus in Beyşehir Lake was investigated. The fatty acid profiles of total lipid, phospholipid, and triacylglycerol in muscle and liver of male and female L. lepidus were evaluated by gas chromatography. Proximate analyses showed that meat of male and female L. lepidus had 15.13 ± 0.04 and 18.75 ± 0.11% fat, 20.42 ± 0.45 and 22.21 ± 0.56% protein, 65.47 ± 1.37 and 61.28 ± 1.03% moisture, and 1.51 ± 0.05 and 1.50 ± 0.03% ash, respectively. The percentage of total saturated fatty acids was higher in liver than in muscle, whereas the total polyunsaturated fatty acid (PUFA) content was the lowest in all fatty acid profiles. The phospholipids contained more PUFAs than triacylglycerol. Analysis of variance indicated significant differences (P<0.05) between male (47.51%) and female (49.98%) muscle PUFAs in total lipid. The proportion of omega 3 (ω3) to omega 6 (ω6) fatty acids of total lipid was 3.15 in male and 3.68 in female. The ratio is an important indicator for comparing the value of fish oil. Therefore, it was concluded that L. lepidus was considered to be a high quality product for healthy food choice. Additionally, female L. lepidus may especially be used to produce fish oil supplements from freshwater fish combined with vegetable oils. [ABSTRACT FROM AUTHOR]

A method for the mass marking of ide Leuciscus idus larvae by feeding them Artemia salina nauplii that were immersed in different solutions of alizarin red S, tetracycline hydrochloride and calcein was tested. The best quality marks were obtained after feeding fish for 4 days with nauplii that had been immersed in 200 mg l−1 alizarin red S. [ABSTRACT FROM AUTHOR]

Amur ide (Leuciscus waleckii), an important aquaculture species, inhabits neutral freshwater but can tolerate high salinity or alkalinity. As an extreme example, the population in Dali Nor lake inhabits alkalized soda water permanently, and migrates from alkaline water to neutral freshwater to spawn. In this study, we performed comparative transcriptome profiling study on the livers of Amur ide to interrogate the expression differences between the population that permanently inhabit freshwater in Ganggeng Nor lake (FW) and the spawning population that recently migrated from alkaline water into freshwater (SM). A total of 637,234,880 reads were generated, resulting in 53,440 assembled contigs that were used as reference sequences. Comparisons of these transcriptome files revealed 444 unigenes with significant differential expression (p-value ≤ 0.01, fold-change ≥ 2), including 246 genes that were up-regulated in SM and 198 genes that were up-regulated in FW. The gene ontology (GO) enrichment analysis and KEGG pathway analysis indicated that the mTOR signaling pathway, Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway, and oxidative phosphorylation were highly likely to affect physiological changes during spawning migration. Overall, this study demonstrates that transcriptome changes played a role in Amur ide spawning migration. These results provide a foundation for further analyses on the physiological and molecular mechanisms underlying Amur ide spawning migration. [ABSTRACT FROM AUTHOR]

Otolith Sr:Ca and Ba:Ca profiles were used in parallel with age data to investigate the life-history characteristics of ide, Leuciscus idus (L.) ( n = 111), in the Väinameri Sea, West Estonia. Sr:Ca profiles were more variable and useful than Ba:Ca profiles. Flexible life-history patterns were observed within and among the three study sites. Most of the individuals (72%) hatched in semi-enclosed bays that are fresh water during spring spawning but are often flooded with brackish water during other seasons. The importance of lotic spawning varied among sites and was the highest (88%) in Matsalu Bay, moderate in Saunja Bay (33%) and lowest (0%) in Käina Bay. Young of the year emigrated from natal sites and entered the sea within the first summer; 95% did so during the first month post-hatch. Juvenile ide undertook non-spawning, freshwater migrations in the following spring; however, the reasons behind this phenomenon remain unknown. As the importance of lotic spawning has significantly decreased and multiple historically important ide spawning rivers lack anadromous runs altogether, it is suggested that actions should be taken to aid the recovery of those imperilled spawning stocks. [ABSTRACT FROM AUTHOR]

Allometric growth and ontogeny were studied in ide Leuciscus idus (L.) reared in laboratory conditions from 0 to 30 days post hatching ( DPH), to define important steps in the species' early life history. Based on the external morphology, eleven different stages during the early development of ide were identified ( ES9a - JS1a; ES - embryonic stage, JS - juvenile stage). After a short period of rest, hatched individuals were visual feeders with a pelagic life. Organogenesis and allometric changes indicated that development priorities concerned feeding efficiency, respiration efficiency and locomotion performances. Also concluded was that the gradual changes observed in body proportions (which occurred across a wide range of body lengths) reflect the absence of abrupt changes in the behaviour and habitat and may also be considered as a gradual adaptation to life in flowing water. [ABSTRACT FROM AUTHOR]

Population age structure of ide Leuciscus idus in the eastern Baltic Sea was investigated using samples from three sites in the Väinameri Sea. Using the otolith thin sections for the first time on ide otoliths, a new maximum age of 29 years was observed. It is suggested that otolith thin sections should be preferred to scales if clear-cut and accurate age determinations of ide are desired. The results demonstrated that ide population in the Baltic Sea may consist of individuals with more variable age range than previously reported. There was a significant difference in adult age structure among study sites (spawning stocks), which was also reflected in the overall abundance of ide in the particular site. Higher growth rates were recorded compared to historical datasets collected from the same region. A strong positive relationship between age and otolith weight was observed. Potential factors behind the differences in age structure and abundance among study sites are discussed. [ABSTRACT FROM AUTHOR]

The aim of the present study was to perform quantitative and qualitative evaluations of developing blood cells in the head kidney of European chub, Squalius cephalus (L.). Twenty-one types of hematopoietic precursors and mature cells were identified in head kidneys isolated from ten juvenile fish. The lymphoid lineage was the most abundant, followed by granuloid, erythroid, thrombocytoid, blast, and monocytoid cells. The lymphocyte was the most frequently occurring cell in the kidney and the most numerous of the lymphoid cells. The neutrophilic lineage was the most numerous among the granuloid cells. The erythropoietic series comprised five stages (erythroblasts: basophilic, polychromatic, orthochromatic; young and mature erythrocytes), more than the numbers of developmental stages of any other lineages. Juvenile cells were more abundant than mature stages in the head kidney. Only mature eosinophils and thrombocytes were found in chub hematopoietic tissue. The cellular composition in chub hematopoietic tissue was similar to that in other fish species. [ABSTRACT FROM AUTHOR]

Hosts have evolved two distinct defence strategies against parasites: resistance (which prevents infection or limit parasite growth) and tolerance (which alleviates the fitness consequences of infection). However, heritable variation in resistance and tolerance and the genetic correlation between these two traits have rarely been characterized in wild host populations. Here, we estimate these parameters for both traits in Leuciscus burdigalensis, a freshwater fish parasitized by Tracheliastes polycolpus.We used a genetic database to construct a full-sib pedigree in a wild L. burdigalensis population.We then used univariate animal models to estimate inclusive heritability (i.e. all forms of genetic and non-genetic inheritance) in resistance and tolerance. Finally, we assessed the genetic correlation between these two traits using a bivariate animal model. We found significant heritability for resistance (H � 17.6%; 95% CI: 7.2�32.2%) and tolerance (H � 18.8%; 95% CI: 4.4�36.1%), whereas we found no evidence for the existence of a genetic correlation between these traits. Furthermore, we confirm that resistance and tolerance are strongly affected by environmental effects. Our results demonstrate that (i) heritable variation exists for parasite resistance and tolerance in wild host populations, and (ii) these traits can evolve independently in populations. [ABSTRACT FROM AUTHOR]

Three groups (wild-WS, semi-pond-SPS, and pond-cultured-PS) of ide Leuciscus idus (L.) were examined. Each group consisted of 30 females and 10 males, aged 5-8 years. All groups were stimulated with two agents: carp pituitary homogenate (CPH) and a synthetic hormonal preparation Ovopel. The amount of ovulating females decreased in conjunction with females' domestication level, mainly because of very low efficacy of CPH for pond-reared ide stimulation. The percentage of ovulating females stimulated with Ovopel (97.0 %) was significantly higher comparing to CPH (63.0 %). No significant differences were found in latency time between the groups but spawning synchronization increased in conjunction with ide domestication. The positive correlation between domestication level and latency time, i.e., the higher the domestication level, the higher the latency time, was stated. No significant differences were found in PGSI as well as in total volume of obtained eggs, but groups differed significantly in the number of dry eggs and in number of swollen egg. Significant negative correlation between domestication level and number of swollen eggs, i.e., the higher the domestication level, the lower the number of eggs, was detected. The survival rate at the eyed stage was the highest in WS group (60.4 %) and PS group (57.7 %), and was significantly higher than in SPS group (51.8 %). Eggs obtained after CPH stimulation had higher survival rate at the eyed-egg stage (60.3 %) than eggs obtained from the fish stimulated with Ovopel (53.0 %). The data suggest that some form of domestication appeared in ide cultivated for several generations in carp pond. [ABSTRACT FROM AUTHOR]

Laboratory-reproduced and bred asps were experimentally infected with Contracaecum rudolphii larvae, either directly or with previously infected copepods. In the fish exposed to larval infection, the intensity and prevalence of infection were noticeably higher than in the group exposed to copepods. The course of larvae development was similar in both groups. In the larvae measuring ca. 1000 μm in length, the gastrointestinal tract with a developed ventriculus, ventricular appendix and intestinal caecum was clearly visible. The mouth was surrounded by three lips. Over the 10-week experimental period, slightly-coiled larvae surrounded with a thin theca but no encysted larvae were found in the fish exposed to larvae. On the other hand, spirally-stranded and encysted larvae were observed after the 7th week in the fish exposed to infected copepods. The results demonstrated that in the experimentally infected asps, the intensity and prevalence of infection as well as the location of the larvae in a fish depended on the type of invasive material applied. [ABSTRACT FROM AUTHOR]

Background: Amur ide (Leuciscus waleckii) is an economically and ecologically important species in Northern Asia. The Dali Nor population inhabiting Dali Nor Lake, a typical saline-alkaline lake in Inner Mongolia, is well-known for its adaptation to extremely high alkalinity. Genome information is needed for conservation and aquaculture purposes, as well as to gain further understanding into the genetics of stress tolerance. The objective of the study is to sequence the transcriptome and obtain a well-assembled transcriptome of Amur ide. Results: The transcriptome of Amur ide was sequenced using the Illumina platform and assembled into 53,632 cDNA contigs, with an average length of 647 bp and a N50 length of 1,094 bp. A total of 19,338 unique proteins were identified, and gene ontology and KEGG (Kyoto Encyclopedia of Genes and Genomes) analyses classified all contigs into functional categories. Open Reading Frames (ORFs) were detected from 34,888 (65.1%) of contigs with an average length of 577 bp, while 9,638 full-length cDNAs were identified. Comparative analyses revealed that 31,790 (59.3%) contigs have a significant similarity to zebrafish proteins, and 27,096 (50.5%), 27,524 (51.3%) and 27,996 (52.2%) to teraodon, medaka and three-spined stickleback proteins, respectively. A total of 10,395 microsatellites and 34,299 SNPs were identified and classified. A dN/dS analysis on unigenes was performed, which identified that 61 of the genes were under strong positive selection. Most of the genes are associated with stress adaptation and immunity, suggesting that the extreme alkaline-saline environment resulted in fast evolution of certain genes. Conclusions: The transcriptome of Amur ide had been deeply sequenced, assembled and characterized, providing a valuable resource for a better understanding of the Amur ide genome. The transcriptome data will facilitate future functional studies on the Amur ide genome, as well as provide insight into potential mechanisms for adaptation to an extreme alkaline-saline environment. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the effect of age of female ide on spawning success under controlled conditions. All ide breeders were collected from one wild population. Data concerning reproductive parameters were collected during induced spawning under hatchery conditions. The age of mature females ranged from 4 (average weight 504 g) to 9 years (average weight 2540 g) and the youngest collected females (3+) (average weight 330 g) were immature. The females from group 4+ produced smaller oocytes (1.28 mm diameter after hydration) than older fish (1.44-1.57). There were no differences in oocyte sizes in females 6+ and older. The highest relative fecundity (mean 44,621 eggs kg-1) was noted for fish aged from 5 to 7. Eggs obtained from the oldest females had the lowest biological quality: the highest percentage of dead embryos during incubation (49.9) and the highest percentage of morphological abnormalities in hatched larvae (5.6%). In addition, in the group of the oldest females, only 67% of fish produced eggs. [ABSTRACT FROM AUTHOR]

In this study the effect of six activating buffers on the movement parameters of sperm were determined and short-term storage of semen in TLP buffer was attempted (0.292 g NaCl; 0.012g KCl; 0.011g CaCl2; 0.004g MgCl2; 0.105g NaHCO3; 0.002g NaH2PO4; 50 mL; pH 8.6). Sperm was collected from five orfe individual, and spermiation was stimulated by means of an intraperitoneal Ovopel injection. The basic parameters of spermatozoa motility were measured after the semen was diluted with six different activating solutions, previously used successfully in other fish species. The motility analysis was conducted on a Crismas apparatus. Additionally, short-term storage of semen in TLP buffer was attempted. Subsequently, motility parameters were verified after 0 (Control), 24 and 120 h of storage at 4°C. It has been found that Lahnsteiner's buffer (100 mM NaCl, 10 mM Tris, 0.5% albumin, 199 mOsmkg-1) was found to be the most effective in sperm activation. In this paper, the spermatozoa motility of colourful ide is indicated for the first time. Finally, there was a successful attempt at short-term sperm storage for five days. For artificial insemination, it is very important to select the most effective solution to stimulate sperm motility. Data regarding sperm manipulation of orfe are scarce, so the aim of the study was to determine the basic sperm quality parameters of the colour ide form, i.e. Leuciscus idus aberr orfus. [ABSTRACT FROM AUTHOR]

The efficiency of individual genetic tagging was determined by using passive integrated transponders (PIT) as a comparative conventional tagging method. Fifty-five common dace Leuciscus leuciscus were captured in the wild, PIT tagged and fin clipped (for DNA analysis). Thirty fish were recaptured on three occasions and tissue samples were collected. Using 18 microsatellite loci, 79-94% of the recaptures were correctly assigned. Experience with scoring L. leuciscus microsatellites led to more individuals correctly assigned. Allowing matches that differed by one or two alleles resulted in 100% of all recaptures successfully assigned irrespective of the observer. Reducing the set of loci to five to six loci appropriately selected did not affect the assignment rate, demonstrating that costs can be subsequently reduced. Despite their potential benefits, the application of genetic tags for teleosts has been limited. Here, it was demonstrated that genetic tagging could be applied, and a clear guideline (flowchart) is provided on how this method can be developed for teleosts and other organisms, with subsequent practical applications to ecology, evolutionary biology and conservation management. [ABSTRACT FROM AUTHOR]

Two forms of ide Leuciscus idus (L.) spawners: wild-coloured and ornamental: yellowcoloured were kept at three various temperature regimes shortly before spawning at optimal temperature regimes (group 1), under natural temperature conditions (group 2) and in rapidly increasing temperature (group 3). The quality and quantity of collected semen, ovulation rate and survival rate of embryos to the eyed-egg-stage were recorded. The quality of semen from group 3 (where the temperature increased over the thermal spawning optimum) was the worst (46 and 51% motility of spermatozoa for the wild-coloured and yellow form, respectively). The quantity of collected semen also was the lowest in the same groups (1.1 and 1.0 cm3 kg-1 for the wild-coloured and yellow form, respectively). Increasing the temperature to 16°C also caused a decreasing percentage of ovulated females (70% and 60% of ovulation for wild-coloured and yellow form, respectively) and biological quality of eggs (48.9 and 47.8% embryo survival for wildcoloured and yellow form, respectively). Fluctuations of temperature at a level of 8- 14°C (group 2) did not negatively affect spawning results, except for a longer latency time (over 44 hrs). The results suggest that the temperature regime shortly before controlled reproduction of ide plays an important role influencing reproductive success. [ABSTRACT FROM AUTHOR]

This study was aimed at determining the effect of stocking density on growth, survival and development of asp Aspius aspius (L.), ide Leuciscus idus (L.) and chub Leuciscus cephalus (L.) larvae, reared under laboratory conditions. Fish larvae were obtained during artificial reproduction. The larvae were fed ad libitum with freshly hatched Artemia sp. nauplii. Eight density variants from 50 to 400 individuals per 1 L (at the interval of 50 individuals L-1) were tested. The initial rearing was carried out for 21 days at 25°C in a recirculation system especially designed for that purpose consisting of 16 tanks with a capacity of 1 L each. The fastest growth rate for all three species, expressed as the greatest average total length, weight and most advanced ontogenetic stage at the end of the experiment was obtained at the lowest stocking density. Fish from other treatments, particularly at densities exceeding 150 individuals L-1, were characterized by similar body sizes and the same ontogenetic stage on the last day of rearing. The recorded differences in the length of larvae among treatments became visible during the first (asp) or third (chub, ide) week of rearing. No effects of stocking density on larval mortality were found during the experiment. [ABSTRACT FROM AUTHOR]

Milt of the Leuciscus idus L. was collected from five experimental groups, and selected parameters of its quality were analysed for 36 h (group II), 60 h (group III), 84 h (group IV) and 108 h (group V), respectively, after hormonal stimulation with Ovopel (1 granule kg−1 of body weight). The control (group I) fish were not subjected to hormonal stimulation. The highest milt volume was obtained from the fish in group IV (0.70 ± 0.55 mL), where the largest volume of milt expressed per kilogram was also obtained (3.03 ± 1.94 mL kg−1). Significant differences were also found in milt volumes obtained between group I and groups III ( P<0.01) and IV ( P<0.05). The highest percentage of motile spermatozoa was found in the milt of group IV (59%); significant differences were found between group I and groups II ( P<0.01) and III ( P<0.001). The value of osmotic pressure of seminal plasma was the highest in group IV (203.19 ± 37.63 mOsm kg−1), and the lowest in group I (118.31 ± 41.13 mOsm kg−1). Parameters determining milt quality and quantity indicate that the period of 60–84 h after hormonal stimulation with Ovopel is optimal for obtaining milt from ide. [ABSTRACT FROM AUTHOR]

Panjet-applied alcian blue did not produce a reliable long-term (> 5 months) mark. Average time to mark loss was 9·5 months for chub Leuciscus cephalus, 6·0 months for dace Leuciscus leuciscus and 11·1 months for roach Rutilus rutilus. Growth rate did not influence retention. [ABSTRACT FROM AUTHOR]

Valuable biological information can be obtained by monitoring the movement of organisms. However, the choice of monitoring method becomes highly restricted when following small organisms (<100 mm), especially in aquatic ecosystems. Stable isotopes are being increasingly used in this respect but rarely at the local spatial scale, i.e. 10–1000 s of metres. We sought to identify movement of small fishes between a main river channel and its tributary. Little overlap in isotope baseline was detected between the two channels despite some temporal variability in δ15N of baseline indicator organisms in the main river. The individuals of two small cyprinid fish species ( Leuciscus souffia and Alburnoides bipunctatus) of all the size classes (40–100 mm) caught within the tributary showed considerable heterogeneity in δ15N values. Classification and discriminant analysis on isotope-derived data distinguished two significantly different groups. Moreover, this result was supported by further sampling of fish caught in the main river (in May and December 2006). Alternative hypotheses, such as dietary differences, biological factors, temporal shifts and spatial differences in diet, did not explain δ15N variability. This application of stable isotopes at a relatively small spatial and temporal scales further demonstrates its potential as a tool for ecologists. [ABSTRACT FROM AUTHOR]

Background: Cyprinids display the most abundant and widespread species among the European freshwater Teleostei and are known to hybridize quite commonly. Nevertheless, a limited number of markers for conducting comparative differentiation, evolutionary and hybridization dynamics studies are available to date. Findings: Five multiplex PCR sets were optimized in order to assay 41 cyprinid-specific polymorphic microsatellite loci (including 10 novel loci isolated from Chondrostoma nasus nasus, Chondrostoma toxostoma toxostoma and Leuciscus leuciscus) for 503 individuals (440 purebred specimens and 63 hybrids) from 15 European cyprinid species. The level of genetic diversity was assessed in Alburnus alburnus, Alburnoides bipunctatus, C. genei, C. n. nasus, C. soetta, C. t. toxostoma, L. idus, L. leuciscus, Pachychilon pictum, Rutilus rutilus, Squalius cephalus and Telestes souffia. The applicability of the markers was also tested on Abramis brama, Blicca bjoerkna and Scardinius erythrophtalmus specimens. Overall, between 24 and 37 of these markers revealed polymorphic for the investigated species and 23 markers amplified for all the 15 European cyprinid species. Conclusions: The developed set of markers demonstrated its performance in discriminating European cyprinid species. Furthermore, it allowed detecting and characterizing hybrid individuals. These microsatellites will therefore be useful to perform comparative evolutionary and population genetics studies dealing with European cyprinids, what is of particular interest in conservation issues and constitutes a tool of choice to conduct hybridization studies. [ABSTRACT FROM AUTHOR]

La présente étude rapporte le premier signalement d'un cas de leucisme chez une espèce de Narcine, Narcine bancrofti (Griffith & Smith, 1834). Cette raie leucique, un mâle immature, a été capturée avec 21 congénères présentant la coloration normale de l'espèce. Dix-neuf de ces animaux, y compris la raie leucique, ont été conservés pour un examen plus approfondi. Douze mesures morphométriques ont été réalisées sur chacune d'entre-elles et rapportées à la longueur totale afin d'identifier si des anomalies morphologiques supplémentaires étaient présentes. Dans chaque cas, la raie leucique présentait des proportions relatives similaires à celles des spécimens de coloration normale. [ABSTRACT FROM AUTHOR]

Ten novel polymorphic microsatellites were isolated from the dace complex ( Leuciscus leuciscus), which is a European cyprinid species. Four multiplex polymerase chain reaction sets were optimized in order to genotype 26 polymorphic loci in all, including 16 previously published cyprinid-specific loci. The level of genetic diversity was assessed in 142 dace individuals. We also successfully applied 26 of the microsatellites to 10 related species. These primers thus will be useful to assess population structure of the dace and other cyprinid species, with application for conservation issues and phylogeographical approaches. [ABSTRACT FROM AUTHOR]

Seventeen individuals of ide Leuciscus idus were radio-tracked weekly from September 2003 to September 2004 in the River Elbe, Czech Republic, to examine migration patterns and the influence of environmental factors on their diurnal behaviour. Of the 10 environmental factors measured, L. idus were significantly influenced by turbidity, which increased diurnal movement and the home range size of the species. The peak of longitudinal movement occurred in the spring, indicating pre-spawning migration. Migrating fish moved downstream and later returned upstream to the vicinity of their original locations, displaying a homing behaviour. [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs), hexachlorocyclohexane (HCH) isomers, dichlorodiphenyltrichloroethane (DDT) and its metabolites, other organochlorine pesticides such as hexachlorobenzene (HCB), chlordane compounds (CHLs, including trans-chlordane and cis- and trans-nonachlor) and the heavy metal mercury were quantified in muscle and liver of the European chub (Leuciscus cephalus, Linnaeus, 1758) and in the muscle of the barbel (Barbus cyclolepis, Heckel, 1837) at two sampling sites of the River Nestos, Greece. PCBs in muscle and DDTs in the liver tissues were the predominant organochlorinated contaminants. Among the PCBs, congeners 47 (up to 9.60ngg−1 wet wt.), 180 (up to 1.15ngg−1 wet wt.) and 190 (up to 1.50ngg−1 wet wt.) were the most frequent and abundant. The contamination degree by the sum of PCBs on the fish tissue samples from the River Nestos is lower or similar to PCB levels found in other ecosystems. Among the organochlorine pesticides, essentially only p,p′-DDD, p,p′-DDE and α-, β- and γ-HCH were found, with the former appearing at mean levels up to 30.71ngg−1 wet wt. From a public health standpoint, residue organochlorine pesticide levels from our work are considerably lower than the recommended tolerance limits. Finally, mean values of Hg in chub were significant lower (up to 31.04ngg−1 wet wt.) compared to those detected on barbel (up to 169.27ngg-1 wet wt.). The concentrations of Hg in fresh water fish from the River Nestos did not exceed WHO and US EPA health guidelines, and were suitable for human consumption. [Copyright &y& Elsevier]

Thirteen polymorphic microsatellites were isolated from Leuciscus cephalus, a widespread cyprinid species with great ecological tolerance. Together with the cross-species amplification of six additional loci originally published for three cyprinid fish species, we optimized a multiplex panel for L. cephalus allowing the genotyping of 19 polymorphic loci. Number of alleles and heterozygosity per locus in a sample of 20 fish individuals ranged from two to 16 and from 0.05 to 0.90, respectively. These primers will be useful in determining the population structure of L. cephalus. In addition, successful cross-amplification was obtained for several species of Cyprinidae. [ABSTRACT FROM AUTHOR]

Biometric evaluation, ovary histomorphometry, plasma 17β-estradiol (E2) and androgens (A) concentrations were investigated through the gonadal maturation and spawning of the wild chub, Leuciscus cephalus. A lower concentration of plasma E2 was recorded from January (oogonia) to March (previtellogenic oocytes), while estradiol concentrations increased in April, when the ovary mostly contained vitellogenic oocytes. In July, when it was prevalently composed of post-ovulatory follicles, there was a decline in E2 plasma concentrations. Low concentrations of this steroid remained in the plasma until January, while high concentrations of androgens reached a peak in February and April preceding and following E2. The observed seasonal changes in plasma steroids, reflecting the pattern of follicles size development, were to a large extent consistent with observations made in other cyprinids. Since they define the reproductive cycle of the European female chub, they will be useful in the construction of a maturity schedule for wild populations. [ABSTRACT FROM AUTHOR]

Angel-related element belongs to the family of miniature inverted-repeat transposable elements (MITEs). In this paper we report the identification of an Angel-related element in the series Leuciscini of cyprinid fishes, which is located in the second intron of the growth hormone (GH) gene. We have also found that this element is absent in orthologous locus in the series Barbini of cyprinid fishes, that provides new evidence for the monophyly of the series Leuciscini. The insertion of Angel-related element into the GH gene might take place in the common ancestor of the series Leuciscini after its divergence from the series Barbini. The high sequence divergence and relatively broad species distribution of Angel-related elements implies that they might be ancient transposons which appeared about 26 million years ago. [ABSTRACT FROM AUTHOR]

Abstract: The dace (Leuciscus leuciscus), with a very large geographic distribution all over Europe, represents an interesting species model for studies of the global mechanisms underlying aquatic system biodiversity. To assess the congruence with the past colonization process hypothesis of the freshwater fauna in Western Europe, we investigated the evolutionary history of this species, by integrating morphological variation (eight meristic characters), mitochondrial (cytochrome b, 16S rDNA and control region, over a total of 2169bp) and nuclear (12 allozymes loci) phylogenetic relationships, and investigating population dynamics via expansion, migration, bottleneck, and divergence time analyses. We carried out nested clade phylogeographic analysis for a total of 663 specimens from 31 populations taken from all over the distribution area. Unlike previous studies, we found that L. leuciscus is currently constituted by five lineages belonging to two clades (yielding 6.3% of pairwise divergence). The relationships between these lineages were accounted for by complex biogeographical patterns due to Pliocene and Pleistocene paleoclimatic events, validating the identification of new glacial refuges for freshwater fish in Western Europe. Finally, we demonstrated hybridization between L. leuciscus and Leuciscus idus. [Copyright &y& Elsevier]

The sex distribution, growth in length and weight, growth rates and condition factors of Chub (Leuciscus cephalus (L.,1758)) in Karakaya dam lake were examined. Females made up 63.64% and males 36.37% (1.75:1) of 527 samples. The females and males were in the I-VI and I-V age groups, respectively. The reproductive properties of L. cephalus such as spawning period, age at attainment of maturity, egg diameter and ovarium weight were investigated. Students t test showed that differences in length and weight between females and males of the same age groups were statistically insignificant (P > 0.05). The growth, both in length and weight, was calculated according to the von Bertalanffy equation for females and males respectively: Lt = 37.8 [1-e-0.4125(t-(-1.0013))], Wt = 775.3 [1-e -0.4125(t-(-1.0013))] 3.0272 and Lt = 35.45 [1-e -0.6062(t-(-0.1883))], Wt = 590.5 [1-e-0.6062(t-(-0.1883))] 2.4878. The calculated length-weight relation for females was W = 0.013 L3.0272 and for males W = 0.0824 L2.4878. The average condition factor was 1.42 ± 0.05 for females and 1.43 ± 0.25 for males. According to gonado-somatic index (IG) results and the development of egg diameter, it was determined that the spawning period of L. cephalus occurs in May and June. Sexual maturity was attained in the third year. The mean diameter of ripe eggs was 1.06 mm and the mean number of eggs per gram of gonads was 1265. [ABSTRACT FROM AUTHOR]

Metallothionein has been assayed in a range of aquatic animal tissues as an indicator of metal exposure. We sequenced chub (Leuciscus cephalus) metallothionein cDNA which showed over 90% homology to common carp, goldfish and stone loach and 77% homology to rainbow trout sequences for metallothionein. We then used the extended primer method to develop an accurate quantitative competitive RT-PCR assay for metallothionein mRNA. RT-PCR was used to measure metallothionein mRNA in feral chub from a range of field sites, with different levels of heavy metal pollution, in the West Midlands, UK. Measurements were complemented by analysis of liver and gill metallothionein protein by capillary electrophoresis. There was no significant difference in the metallothionein protein levels between fish of different rivers and there was no evidence of elevation of mRNA at the sites of highest metal exposure. The level of metal exposure (e.g. zinc, nickel and cadmium each ranging between 15 and 28 μg/l ) at the pH (7.5–8.5) of these rivers appears insufficient to elevate hepatic or gill metallothionein in chub. A lack of elevation of hepatic metallothionein mRNA in chub exposed to zinc, copper and manganese for 24 h and 10 days in the laboratory also suggests a non-responsiveness of this species. [Copyright &y& Elsevier]

Individual movement patterns of adult ide Leuciscus idus , a Eurasian river-dwelling cyprinid, in two lowland rivers were measured all year-round during 1997–2000 to assess migratory behaviour and variation between and within these populations. In the River Elbe, a 1091 km long lowland river with a free flowing stretch of 590 km, 24 ide were implanted with radio transmitters. Fish were hand-tracked all year-round once a week in the main study area (75 km), and once per 6 weeks in a larger area (321 km). In the River Vecht, a 190 km long highly regulated river with six weirs and fishways in the Dutch section, 25 ide were implanted with transponders. An array of three automatic detection stations covering the entire river width, registered each individual passage continuously. Within population variation in year-round movement patterns was very high. In both rivers a similar continuum was found from individuals using a river stretch of only a few km for spawning, feeding and wintering, to individuals migrating >100 km. The populations in the two rivers differed, however, in spawning site fidelity. In the River Vecht spawning site fidelity was observed in all individuals and appeared much stronger than in the River Elbe, where individuals moving downstream >60–90 km tended to adopt new spawning sites in the next year. Moreover, some ide in the River Vecht migrated upstream to wintering habitats in autumn, whereas this was not observed in the River Elbe. The results suggest that ide is a flexible species capable of using a wide variety of movement patterns and scales. [ABSTRACT FROM AUTHOR]

Groynes are the dominant river engineering structures along the lowland section of large European rivers such as the Rhine, Danube and the Elbe. More than 6000 groynes structure the 400 km stretch of the potamal of the Elbe River. After 1945, destruction of the groynes increased through ice and flood events in the eastern part of Germany. In the past ten years, groyne reconstruction was accompanied by a controversial discussion in the context of the ecological integrity of the Elbe River. With the modular habitat model (MHM) a tool was developed to evaluate the suitability and to balance the availability of fish habitats in groyne fields of different conditions. The morphodynamic module produced a digital terrain model and a spatial model of flow velocity for each groyne field separately. Based on point abundance sampling by electro-fishing, models of habitat preference were developed for different life history stages by logistic regression. Statistical models predicting the preference of fish-environment relationships ( Leuciscus idus) at different life history stages. The models were discriminated and validated by receiver operating characteristic (ROC) curves. The link between the statistical and the spatial model was realised in the suitability module. The suitability of microhabitats is expressed in classes for each species and life history stage separately. Habitat availability is balanced on the level of mesohabitat, e.g. different types of groyne fields. The temporal dynamics of habitat availability are analysed by considering different levels of discharge. For the stage ‘juvenile A’ and preadult the habitat suitability is better in fields downstream of destroyed groynes. For ‘juvenile B’ and adult stages of the ide, groyne fields in general constitute low habitat suitability. Differences in spatial availability are higher than the differences in temporal habitat availability. [ABSTRACT FROM AUTHOR]

Origins and biogeography of the chub, genus Squalius (formerly within the genus Leuciscus), in the Iberian Peninsula were inferred from comparison between patterns of geographic distribution and phylogenetic relationships among populations belonging to 14 European Squalius species. The phylogeny recovered was based on the complete sequence of the mitochondrial cytochrome b gene. Squalius species were grouped into three major clades. The basal clade included species distributed across the ancient Paratethys Sea. The second clade included species from Central and East Europe and the northern areas of the Mediterranean basin towards Minor Asia. The third clade included species from the Mediterranean Peninsulas (Iberian, Italy, and Balkans). The Iberian Squalius species do not constitutes a monophyletic group. Our data indicate that the Iberian Peninsula was colonized at least twice by two different monophyletic lineages, a meridional group and a Central Europe group. The amount of species diversity found in the Iberian Peninsula and the phylogenetic relationships among these species, together with their geographic distribution, suggest that the Central Europe lineage colonized the Iberian Peninsula at a latter time. Our data indicate that the northeastern Iberian lineage is phylogenetically close to Greek populations of Squalius cephalus, while the second lineage formed a monophyletic group including Squalius pyrenaicus, Squalius carolitertii, Squalius aradensis, and Squalius torgalensis. The speciation process that generated these species and the geographic structure of their populations, principally in S. pyrenaicus, can be attributed to paleogeographical events like the ancient endorrheism and the development of hydrographic basins. [Copyright &y& Elsevier]

Abstract The vairone Leuciscus souffia is a cyprinid fish that inhabits river systems in and around the Alps. The complete mitochondrial DNA control region (945 bp) was sequenced in 295 vairone from 22 populations in Central Europe. A total of 51 haplotypes were identified with a maximum pairwise distance between haplotypes of 5.6%. Phylogenetic analyses revealed two major clades in L. souffia , an ‘Italian’ clade, and an ‘Alpine’ clade. Two hybrid zones exist, in the Mediterranean Alps and in the Soca basin. The position of the sister species of L. souffia , L. turskyi , to the ‘Alpine’ and the ‘Italian’ clade could not be resolved unambiguously. However, a linearized tree analysis indicated that L. turskyi represents a third lineage, that originated at the same time as the ‘Alpine’ and the ‘Italian’ clades of L. souffia . In the ‘Alpine’ clade two groups were resolved, a subclade with haplotypes from the Rhône and Var basins and a cluster with haplotypes from the Danube and Rhine systems. Our data suggest a long history of the vairone in Central Europe, predating Pleistocene glacial cycles. Two main refugia during glaciations must have existed, one in Italy and another one most probably in the Danube system. However, age estimates based on molecular clock calibrations suggest the survival of ‘Alpine’ haplotypes in several drainages during the last glaciation cycles. The Rhine system was only recently colonized. [ABSTRACT FROM AUTHOR]

SUMMARY 1. Stream reaches contain assortments of various habitat types that can be defined at different spatial scales, such as channel unit (e.g. pools, riffles) and subunit (patches within channel units). We described longitudinal (upstream–downstream) patterns of stream habitat structure by considering subunits as structural elements, and examined their effects on the abundance of masu salmon (Oncorhynchus masou ) and rosyface dace (Leuciscus ezoe ) in a third-order tributary of the Teshio River in northern Hokkaido, Japan. 2. Nine subunit types were determined on the basis of water depth, current velocity and substrate, using 0.5 × 0.5 m grids. Although both masu salmon and rosyface dace used pools as a major habitat, the former preferred a subunit type occurring at pool heads (PH subunit) while the latter preferred a slow-current edge type (SE-2 subunit). 3. Along the course of the stream, slow-edge subunits (SE-1, 2 and 3) increased in frequency downstream while fast-edge subunits (FE-1 and 2) decreased, suggesting a downstream development of slow-current edges. Regression analyses indicated that longitudinal variation in masu salmon abundance was explained by the area of PH, rather than pools. Masu salmon density increased with the area of PH. Rosyface dace abundance was explained by a combination of water depth and the area of SE-2, both effects being positive. 4. Longitudinal variations in the abundance of both species were related to the abundance of their preferred habitat at the subunit scale, rather than channel-unit scale. The results emphasise the importance of fine-scale patchiness when examining stream fish habitats. [ABSTRACT FROM AUTHOR]

Simple conditions and techniques for spawning and rearing the eggs of dace (Leuciscus leuciscus) are described. Incubation at ambient temperatures (mean 8.8°C, range 4.1-13.8°C) in chalk spring water gave a 94.0% hatch. Incubation in river water resulted in a much lower hatching, probably due to silt deposition. A simple exponential model is used to describe the relationship between temperature and hatching time. [ABSTRACT FROM AUTHOR]

Analyses of the fine structure of the posterior choroid plexus in the teleost Leuciscus rutilus and the determination of the presence and function of the enzymes acid and alkaline phosphatases, ATPase and glucose-6-phosphatase confirm similarities between these epithelial cells and the saccus dorsalis and also with the epithelial cells of the choroid plexus found in mammals. The teleost plexus cells contain coated vesicles which are derived from the plasmalemma as well as from the Golgi complex. Moreover, they contain multivesicular bodies and lysosomes. These organelles function in the absorption of substances from the cerebrospinal fluid and in the breakdown of these substances within the cells. The investigated enzymes play an important role in the secretion of electrolytes into the cerebrospinal fluid by active membrane transport. [ABSTRACT FROM AUTHOR]

Saccus dorsalis in Leuciscus rutilus is a very folded area enclosing the epiphysis within its foldings. The dorsal sac consists of a single layer of cuboidal ependymal cells which have cilia and very irregularly shaped microvilli. The presence of vesicles in longitudinal rows indicate that these microvilli are very active. Bulbous outpocketenings from the apical surface contain glycogen. These bulgings may be pinched off into the lumen of the third ventricle forming rounded drops which contain richly glycogen. To increase the surface there are protrusions covered with microvilli. In the cytoplasm between the basis of those microvilli there are several coated vesicles which possibly sign micropinocytotic activity. Coated vesicles are also to be found in the lateral and basal parts of the cell, where they often have taken contact with the cell membrane. The ependymal cells rest upon a broad glycocalyx. In the subependymal connective tissue are wide capillaries with thinwalled fenestrated endothelial cells. The functional significance of these structures is discussed. A PAS-reaction has been done. The ependymal cells and rounded drops in the ventricular lumen showed a positive reaction. [ABSTRACT FROM AUTHOR]

Fluorescein-labelled antibodies against ovine prolactin have been used to localize the prolactin-producing cells in the pituitary gland of the roach, Leuciscus rutilus. Two methods of protein tracing have been used: the direct and the indirect. In the direct method gammaglobulin fractions of rabbit-antisera were conjugated with fluorescein-isothiocyanate. Frozen sections of the pituitary gland were treated with conjugate. Cells with a content of prolactin gave off green fluorescence. Conjugate made from normal rabbit-serum failed to give this result. Blocking-experiments were also used to control the conjugate fluorescence. In the indirect method sheep-anti-rabbit-gammaglobulin was labelled with fluorescein. First the sections of the hypophysis were treated with antiserum from rabbits. After careful rinsing the sections were exposed to the dyemarked sheep-anti-rabbit-gammaglobulin. For orientation in the pituitary gland histological staining was carried out in parallel to that by fluorescence. The investigation has shown that the erythrosinophilic cells in the rostral pars distalis contained prolactin. Since no other cells in the gland were fluorescent, it can be concluded that the eta-cells are the prolactin cells. [ABSTRACT FROM AUTHOR]

The article discusses about a light microscopic studies on the Nucleus Lateralis Tuberis (NLT) and of the Leuciscus rutilus. The neurosecretory nature of the nucleus lateralis tuberis of fishes has long been recognized but little attention has been given to the function of this interesting structrue. There is morphological evidence that NLT may be involved in the regulation of the fish pituitary. Several early workes described connections between the nucleus and the pituitary, and recently some of them, has demonstrated its connection with the pars distalis in the eel.

This article presents an electron microscopic study of the caudal neurosecretory system in fishes, Leuciscus rutilus and Phoxinus phoxinus. Analogous variations between these species have also been described by the author of this article which is supposed valid for the caudal neurosecretory system in teleosts. This neurosecretion is very frequently found as droplets of varying size intermingled with secretion, homogeneously distributed, of the same type as that in the urophysis. In Phoxinus phoxinus the secretion always occurs in the homogeneously distributed form in all parts of the system. In the cell bodies it is often concentrated in peripheral regions and in the cytoplasm of the nuclear invaginations, that is, regions which have a high content of RNA. Neurosecretory cells of both these species vary in diameter from 1000-2200 angstrom.