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PubMed1998

Genetic evidence for different migration routes of freshwater fish into Norway revealed by analysis of current perch (Perca fluviatilis) populations in Scandinavia.

To elucidate the colonization of freshwater fish into Norway following the last deglaciation of Europe 10,000 years ago, we have performed a survey using mitochondrial DNA variation (20 populations) and multilocus DNA fingerprinting (14 populations) of the widely distributed perch (Perca fluviatilis) from the Scandinavian peninsula and the Baltic Sea. Sequence analysis of a 378 bp segment of the perch mitochondrial control region (D-loop) revealed 12 different haplotypes. A nested clade analysis was performed with the aim of separating population structure and population history. This analysis revealed strong geographical structuring of the Scandinavian perch populations. In addition, the level of genetic diversity was shown to differ considerably among the various populations as measured by the bandsharing values (S-values) obtained from multilocus DNA fingerprinting, with intrapopulation S-values ranging from 0.19 in Sweden to 0.84 in the central part of Norway. Analysis of the intrapopulation S-values, with S-value as a function of lake surface area and region, showed that these differences were significant. The mitochondrial and DNA fingerprinting data both suggest that the perch colonized Norway via two routes: one from the south following the retreating glacier, and the other through Swedish river systems from the Baltic Sea area. Perch utilizing the southern route colonized the area surrounding Oslofjord and the lakes which shortly after deglaciation were close to the sea. Fish migrating from the Baltic Sea seem to have reached no further than the east side of Oslofjord, where they presumably mixed with perch which had entered via the southern route. It seems likely that the migration events leading to the current distribution of perch also apply to other species of freshwater fish showing a similar distribution pattern.

Animals↗
PubMed1988

2,3,7,8-Tetrachlorodibenzo-p-dioxin toxicity in yellow perch (Perca flavescens).

Growth, mortality and morphologic lesions in juvenile, hatchery-reared yellow perch, Perca flavescens, were studied after treatment with graded single doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 1-125 micrograms/kg, intraperitoneally). TCDD doses of 25 and 125 micrograms/kg caused 95% mortality by 28 d after treatment, without decreasing body weight. A TCDD dose of 5 micrograms/kg resulted in progressive loss of body weight with cumulative mortality of 80% by 80 d posttreatment. Periodic handling stress did not affect the time course of mortality or cumulative percent lethality in TCDD-treated perch. Fin necrosis, petechial cutaneous hemorrhage, and ascites occurred in perch treated with 5 micrograms/kg or more of TCDD. Thymic atrophy, decreased hematopoiesis in the head kidney, fibrinous pericarditis, focal myocardial necrosis, submucosal gastric edema, and hyperplasia of the epithelium of gill filaments and lamellae occurred in perch dosed with 25 or 125 micrograms/kg. Dose-related splenic lymphoid depletion occurred in perch receiving 5 micrograms/kg or more TCDD, and hepatocyte lipidosis occurred in groups treated with doses of 1 microgram/kg or more TCDD. Thus yellow perch are as responsive to the acute toxic effects of TCDD as some of the more sensitive mammalian species, and neither loss of body weight nor histologic lesions in TCDD-treated perch are sufficient to explain mortality.

Animals↗
PubMed2003

An evaluation of sodium loss and gill metal binding properties in rainbow trout and yellow perch to explain species differences in copper tolerance.

The main objective of the study was to use a species comparison approach in order to understand sensitivity and tolerance differences to copper. We hypothesized that species differences in toxicity would be reflected by differences in copper binding to high-affinity sites on the gill. Specifically, the strength of copper binding (affinity, logK) and maximum number of binding sites (saturation, Bmax) for copper at the gill surface would vary among different species of fish. Two species that are different in their copper sensitivity are the rainbow trout (Oncorhynchus mykiss) and yellow perch (Perca flavescens). We explicitly compared acute toxicity (median lethal concentrations via 96-h LC50s) and whole-body Na+ loss in both organisms in two distinct water chemistries (i.e., hard and soft water). For both species, the copper binding sites at the gill surface were characterized for their affinity and saturability. The binding properties of the gill were quite similar between the two species in each water chemistry. Based on estimations of the free cupric ion concentration, the affinity, or logK, was 8.4 for both species in soft water, whereas in hard water, the affinity was higher (approximately 9.7). The Bmax value in soft water was 1.88 nmol/g for rainbow trout and yellow perch, while in hard water, saturation occurred at 3.63 nmol/g for rainbow trout and 9.01 nmol/g for yellow perch. More importantly, the amount of copper bound to the gills at 50% mortality (i.e., lethal accumulation; the LA50) was different between the two species (yellow perch LA50s were nine times higher than those of rainbow trout in soft water and hard water), indicating that the copper binding to the yellow perch gill must not have been 'biologically reactive.' According to 96-h LC50s, yellow perch were less sensitive to copper than were rainbow trout; however, the difference between the two species was similar in hard water (1.05 vs 4.16 microM) and soft water (approximately 0.10 vs 0.44 microM). Perch were more tolerant because they lost less sodium upon exposure to copper; yet this mechanism of tolerance was not reflected by the amount of copper at the gill surface. The influence of water chemistry on the binding properties of the gill demonstrates the dynamic nature of the gill in maintaining ionoregulatory homeostasis, a key issue in the future development of the chronic biotic ligand model.

Adaptation, Physiological↗
PubMed1989

Occurrence of Proteocephalus percae and P. cernuae in the perch and ruff in northern Finland.

The occurrence of two palearctic Proteocephalus species, P. percae and P. cernuae, in the perch and ruff, respectively, was studied in two areas of northern Finland in 1977-1983. In the Bothnian Bay, 243 perch (Perca fluviatilis) and 406 ruff (Gymnocephalus cernuus) were studied, of which 60% and 40%, respectively, were infected, while in Lake Yli-Kitka the prevalences were 10% in 213 perch and 24% in 307 ruff. Higher mean intensities of infection were found in the Bothnian Bay fish than in those from the lake, but no infected fish had as many as 10 worms. Proteocephalus infection in the perch and ruff did not vary significantly according to the length of the fish in either area, except that no P. percae were found in perch smaller than 70 mm in the lake. There was a prominent seasonal variation in the occurrence of P. cernuae in the ruff in both areas, but especially in the lake, where no proteocephalids were found in the ruff in July-October. Overlapping of generations was evident in P. percae in the sea perch, although only by virtue of the lack of mature worms at the end of the summer. Some mature proteocephalids were also found in winter in both fish species in the sea and in the ruff of the lake. The higher mean intensity values in winter, especially in P. cernuae infection in the sea ruff, may be explained partly by the active feeding of the ruff at this time in spite of very low water temperatures. Feeding activity in the perch is lower in the winter, and hence a lower mean intensity of P. percae infection was seen especially in the lake material at that time.

Animals↗
PubMed2004

Visual fixation of a landing perch by chickens.

Chickens were video recorded while making jumps or flights toward a landing perch, to test hypotheses about visual fixation behaviour. In the first experiment, varying the height above the landing perch of the food container providing the incentive to jump had no effect on head orientation, indicating that the birds were not fixating this object. In the second experiment, hens jumped over six combinations of perch height and distance, and a linear relationship was found at take-off between head orientation and the angular distance of the perch from the horizontal at the eye. This relationship is consistent with fixation of the perch by a linear combination of head and eye rotations, with the head component contributing 73% of the total response. The image of the perch is fixated 20 masculine below that of the bill tip, outside any region of the chicken retina specialised for high acuity vision. Fixation of the perch before jumping must therefore have some function other than inspection with high acuity, such as providing a constraint that enables precise visual control of trajectory and landing manoeuvres.

Animals↗
PubMed1993

Comparison of bone volume and strength as measures of skeletal integrity in caged laying hens with access to perches.

Fractures in spent laying hens are now recognised as a major welfare problem; the objective of this work was to determine whether provision of perches for caged layers would increase bone strength, bone volume or both. Sixteen ISA Brown hens were housed from 18 to 72 weeks old in cages with perches and 16 in similar cages without perches. At the end of lay the birds' tibiotarsi were examined for strength by a three-point loading test and their tarsometatarsi for bone volume by histomorphometry. There was no significant effect of perches on tibiotarsal breaking strength. Hens from both groups showed evidence of osteoporosis, but it was more severe in the birds from conventional cages: tarsometatarsal trabecular bone volume was greater in the hens which had access to perches. A positive correlation was found between trabecular bone volume and the degree of day-time perch usage by individual hens. Provision of perches can have a slight but significant beneficial effect, at least for the leg bones, in increasing the bone volume of caged laying hens.

Animals↗
PubMed2003

Season-related changes in circulating androgen, brain aromatase, and perch-calling in male ring doves.

The perch-call of ring doves (Streptopelia risoria) is related to territorial defence and mate attraction. Perch-calls are sexually dimorphic and individually different in structure. The expression of perch-call is androgen-dependent and is controlled by the action of testosterone on the preoptic-hypothalamic areas. However, it is not known whether the acoustic features of the call vary with the reproductive condition. We studied plasma androgen levels, brain steroid metabolism, and perch-calling of male ring doves kept in winter-like (low temperature, short days) or spring-like (mild temperature, long day) conditions. Circulating levels of androgen were higher in males kept on spring-like condition. Spring males spent more time in perch-calling than winter males. However, a detailed analysis of the call structure revealed no difference for any time or frequency parameter between groups. This work shows that in ring doves season-dependent variations in the circulating levels of androgen are correlated with differences in the amount of time males spend in perch-calling. In addition, the study suggests that in adult males the acoustic structure of the perch-calls is not influenced by season-related changes in androgen levels.

Animals↗
PubMed1995

Perch length in cages for medium hybrid laying hens.

1. ISA Brown hens were housed as groups of 4 from 18 to 72 weeks in 24 cages 450 mm deep, each with a softwood perch of rectangular cross-section fitted across the rear. There were 4 treatments, each with 6 cages: cage widths and perch lengths were 480, 520, 560 or 600 mm. 2. Daytime perching did not differ significantly between the treatments. At night, over the whole year, 81% of birds in the 480 mm cages and 86% in the 520 mm cages roosted on the perch. This figure reached about 95% in the 560 and 600 mm cages, significantly more at most ages than in the 480 mm cages. 3. Feather damage was slightly less, but claw problems slightly more, in the 2 wider treatments than in the 2 narrower treatments. Birds in the wider cages were calmer when approached or handled by humans than those in the narrower cages. This may have been associated with variation in space allowance between the treatments. 4. There was a trend for lower production in the 480 mm cages than in the other treatments which may have been associated with the reduced feeding space in this treatment. There were few other treatment differences in production traits. 5. The balance of the evidence from this study is that when perches are provided in laying cages for medium weight hybrids, 140 mm of perch space per hen is adequate. For the amelioration of a number of the welfare problems of conventional cages, provision of perches should be combined with other modifications.

Animal Husbandry↗
PubMed2004

Form and function in the unique inner ear of a teleost: the silver perch (Bairdiella chrysoura).

Members of the teleost family Sciaenidae show significant variation in inner ear and swim bladder morphology as well as in the relationship between the swim bladder and the inner ear. In the silver perch (Bairdiella chrysoura), a Stellifer-group sciaenid, both the saccular and utricular otoliths are enlarged relative to those in other teleosts. Additionally, its swim bladder is two-chambered, and the anterior chamber surrounds the otic capsule and terminates lateral to the saccules. Structure and function of the auditory system of the silver perch were explored by using gross dissections, scanning electron microscopy, CT scan reconstruction, and auditory brainstem response approach. Several morphological specializations of the auditory system of the silver perch were found, including expansion of the utricular and lagenar otoliths, close proximity between the saccules and the utricles, deeply grooved sulci on the saccular otoliths, two-planar saccular sensory epithelia, and a unique orientation pattern of sensory hair cell ciliary bundles on the saccular sensory epithelium. It was determined that the silver perch can detect up to 4 kHz, with lowest auditory thresholds between 600 Hz and 1 kHz. Audition in the silver perch is comparable to that in the goldfish (Carassius auratus), a hearing "specialist." The morphological specializations of the inner ear and swim bladder of the silver perch may be linked to its enhanced hearing capabilities. The findings of this study support the proposal that sciaenids are excellent model species for investigating structure-function relations in the teleost auditory system.

Air Sacs↗
PubMed2004

Effects of phytoplankton-induced turbidity on predation success of piscivorous Eurasian perch (Perca fluviatilis): possible implications for fish community structure in lakes.

Turbidity can strongly influence predation success of visually oriented fish, especially piscivores such as adult Eurasian perch (Perca fluviatilis). This purely carnivorous species usually becomes a facultative piscivore after two discrete food niche shifts. Perch biomass has been observed to decrease in lakes along the productivity gradient, and then be replaced by cyprinids in non-manipulated eutrophic systems. Until now, this change has been mainly attributed to the competitive superiority of cyprinids for zooplankton prey during the juvenile phase of perch, while the piscivorous phase--as a possible factor influencing the recruitment success of perch--has been neglected. As the abundance of suitably sized prey fish should not be limiting in highly productive systems, we hypothesise that the switch from benthivorous feeding to preying on fish is inhibited by the reduced visibility in eutrophic lakes. We tested this hypothesis in laboratory experiments, where perch were fed two size classes of juvenile cyprinids at different phytoplankton- and bentonite-induced turbidity levels. Predation success was significantly influenced by turbidity level and turbidity source, but not by prey size. These experimental results suggest for the first time that piscivory of Eurasian perch is negatively influenced by different sources of turbidity, and hence low visibility might delay the onset of the food niche shift to fish prey.

Animals↗
PubMed2006

Effects of clay turbidity and density of pikeperch (Sander lucioperca) larvae on predation by perch (Perca fluviatilis).

Increased turbidity reduces visibility in the water column, which can negatively affect vision-oriented fish and their ability to detect prey. Young fish could consequently benefit from high turbidity levels that can provide a protective cover, reducing predation pressure. Perch (Perca fluviatilis) are commonly found in littoral zones of temperate lakes and coastal areas of the Baltic Sea. Pikeperch (Sander lucioperca) spawn in these areas, so perch is a potential predator for pikeperch larvae. We conducted laboratory experiments to test the predation of perch on pikeperch larvae at different turbidity levels (5-85 nephelometric turbidity units), densities of pikeperch larvae (2-21 individuals l(-1)) and volumes of water (10-45 l). The logistic regression showed that the probability of larvae eaten depended significantly on turbidity and volume of water in the bags, while density of larvae was not significant. However, because container size is known to affect predation, the data was divided into two groups based on water volume (10-20 and 25-45 l) to reduce the effects of container size. In either group, probability of predation did not significantly depend on volume, whereas turbidity was significant in both groups, while density was significant in larger water volumes. Thus, high turbidity impaired perch predation and protected pikeperch larvae from perch predation. Because density of larvae was also a significant factor affecting predation of perch, the dispersal of pikeperch larvae from spawning areas should also increase the survival of larvae.

Animals↗
PubMed1990

A radioimmunoassay for perch (Perca fluviatilis) metallothionein.

A sensitive radioimmunoassay (RIA) for the measurement of metallothionein (MT) from perch (Perca fluviatilis) has been developed. The method is a double-antibody RIA with rabbit anti-perch MT serum as first antibody, goat anti-rabbit immunoglobulin G as second antibody, and perch MT conjugated to 125I-labeled Bolton-Hunter reagent as tracer. The rabbit antiserum raised against perch MT recognizes rainbow trout (Oncorhynchus mykiss) MT, but shows little cross-reactivity with horse MT. At a dilution of 1:2000, the MT antibodies bind 36% of the tracer when no cold ligand is present. The sensitivity of the assay is 15 pg perch MT per tube and the practical working range is 0.15-250 ng perch MT per tube. The RIA allows determination of MT in plasma or lysed blood cells at concentrations as low as 3.0 ng/ml and in tissues at levels above 9.0 ng/g (wet weight). Intra- and interassay coefficients of variation were 6 and 10%, respectively.

Animals↗
PubMed2005

Seasonal variations in hepatic Cd and Cu concentrations and in the sub-cellular distribution of these metals in juvenile yellow perch (Perca flavescens).

Temporal fluctuations in metal (Cd and Cu) concentrations were monitored over four months (May to August) in the liver of juvenile yellow perch (Perca flavescens) sampled from four lakes situated along a metal concentration gradient in northwestern Quebec: Lake Opasatica (reference lake, low metal concentrations), Lake Vaudray (moderate metal concentrations) and lakes Osisko and Dufault (high metal levels). The objectives of this study were to determine if hepatic metal concentrations and metal-handling strategies at the sub-cellular level varied seasonally. Our results showed that Cd and Cu concentrations varied most, in both absolute and relative values, in fish with the highest hepatic metal concentrations, whereas fish sampled from the reference lake did not show any significant variation. To examine the sub-cellular partitioning of these two metals, we used a differential centrifugation technique that allowed the separation of cellular debris, metal detoxified fractions (heat-stable proteins such as metallothionein) and metal sensitive fractions (heat-denaturable proteins (HDP) and organelles). Whereas Cd concentrations in organelle and HDP fractions were maintained at low concentrations in perch from Lakes Opasatica and Vaudray, concentrations in these sensitive fractions were higher and more variable in perch from Lakes Dufault and Osisko, suggesting that there may be some liver dysfunction in these two fish populations. Similarly, Cu concentrations in these sensitive fractions were higher and more variable in perch from the two most Cu-contaminated lakes (Dufault and Osisko) than in perch from the other two lakes, suggesting a breakdown of homeostatic control over this metal. These results suggest not only that metal concentrations vary seasonally, but also that concentrations vary most in fish from contaminated sites. Furthermore, at the sub-cellular level, homeostatic control of metal concentrations in metal-sensitive fractions is difficult to maintain in perch with high hepatic metal concentrations.

Animals↗
PubMed1999

Genetic divergence and phylogeographic relationships among european perch (Perca fluviatilis) populations reflect glacial refugia and postglacial colonization.

We used the widely distributed freshwater fish, perch (Perca fluviatilis), to investigate the postglacial colonization routes of freshwater fishes in Europe. Genetic variability within and among drainages was assessed using mitochondrial DNA (mtDNA) D-loop sequencing and RAPD markers from 55 populations all over Europe as well as one Siberian population. High level of structuring for both markers was observed among drainages and regions, while little differentiation was seen within drainages and regions. Phylogeographic relationships among European perch were determined from the distribution of 35 mtDNA haplotypes detected in the samples. In addition to a distinct southern European group, which includes a Greek and a southern Danubian population, three major groups of perch are observed: the western European drainages, the eastern European drainages including the Siberian population, and Norwegian populations from northern Norway, and western side of Oslofjord. Our data suggest that present perch populations in western and northern Europe were colonized from three main refugia, located in southeastern, northeastern and western Europe. In support of this, nested cladistic analysis of mtDNA clade and nested clade distances suggested historical range expansion as the main factor determining geographical distribution of haplotypes. The Baltic Sea has been colonized from all three refugia, and northeastern Europe harbours descendants from both eastern European refugia. In the upper part of the Danube lineages from the western European and the southern European refugia meet. The southern European refugium probably did not contribute to the recolonization of other western and northern European drainages after the last glaciation. However, phylogenetic analyses suggest that the southern European mtDNA lineage is the most ancient, and therefore likely to be the founder of all present perch lineages. The colonization routes used by perch probably also apply to other freshwater species with similar distribution patterns.

Animals↗
PubMed2004

Molecular characterization and expression of vitellogenin receptor from white perch (Morone americana).

A full-length (4021 base pair [bp]) cDNA encoding a polypeptide (844 amino acids) with a predicted mass of 93 kDa and other characteristic structural features of a vertebrate vitellogenin receptor (VgR) was isolated from a white perch (Morone americana) ovarian cDNA library. Northern blotting performed using a specific digoxygenin-labeled VgR cDNA probe revealed a distinct approximately 4.1 kilobase (kb) hybridization signal in an mRNA preparation obtained from previtellogenic perch ovaries. The deduced amino acid sequence of the perch VgR was 89% and 82% identical, respectively, to that of the tilapia and rainbow trout. Because it possessed an eight-repeat ligand-binding domain (LR8) but lacked an O-linked sugar domain (-), the perch VgR was identified as a non-O-linked form of VgR (LR8-). Unlike the case in other vertebrates investigated, including tilapia and trout, no species of mRNA encoding an O-linked form of VgR (LR8+) could be detected when perch ovarian or liver mRNA reverse transcripts or cDNA libraries were screened by PCR using primer sets flanking the putative O-linked sugar domain. These novel findings call into question the assumptions that an LR8+ splice variant of the VgR always is dominantly present in somatic tissues and exists at lower levels in ovarian tissues to sequester lipoproteins distinct from Vg. A SYBR-green-based real-time reverse transcription-polymerase chain reaction assay was developed and used to quantitatively measure VgR expression in gonadal and somatic tissues, for the first time in any vertebrate. The main site of perch VgR mRNA expression was the ovary and the highest level of VgR mRNA expression was in ovaries whose largest follicles contained previtellogenic oocytes. Expression of VgR mRNA decreased with oocyte growth during vitellogenesis and was very limited in ovulated eggs. These quantitative results verify the concept that growing oocytes must extensively recycle LR8- forms of the VgR.

Alternative Splicing↗
PubMed1993

Effects of perches on trabecular bone volume in laying hens.

Trabecular bone remodelling is known to be affected by loading or exercise, and thus exercise may effect the trabecular bone loss associated with osteopenia in laying hens. Sixteen ISA Brown hens were housed from 18 to 72 weeks old in cages with perches and 16 in similar cages without perches to examine the effects of the exercise afforded by perch provision on trabecular bone volume. At 72 weeks, mean trabecular bone volume in the proximal tarsometatarsus of birds with access to perches was significantly greater than in control birds, while medullary bone volume was not significantly different in the two groups. However, all the birds were considered osteoporotic, though to varying degrees, and the beneficial effects of perches were relatively minor. It was concluded that while trabecular bone loss may be reduced by perch provision, other factors are probably more influential in the development of the osteoporosis typical of laying hens.

Animals↗
PubMed1992

Changes in the density, population structure, growth and reproduction of perch, Perca fluviatilis L. in two acidic forest lakes in southern Finland.

The density of the perch populations decreased rapidly during the 1980s in two acidified lakes in southern Finland. In an acid-humic lake the density of the perch population decreased from 240 to 60 ha(-1) and in an acid clearwater lake from 150 to 20 ha(-1). In both lakes the rapid decrease was mainly due to failures in reproduction, although post-spawning mortality of adult fish was also recorded. The perch spawned annually in both lakes but according to the field exposures of egg strands, most of the eggs died before hatching. Nevertheless, some new recruits appeared in both lakes. These perch, born in 1983-1986, grew faster than those of the more abundant year-classes of the late 1970s, indicating a clear density-dependent growth response. According to the mortality estimate and the age distribution of perch, the latest year-classes that produced more than 100 adult perch ha(-1) were born in 1978 or 1979 in both lakes. It was calculated that the density of both populations was >500 ha(-1) in the early 1980s.

Journal Article↗
PubMed1987

Differential effects of pinealectomy on circadian rhythms of feeding and perch hopping in the European starling.

To study the effects of pinealectomy on the circadian rhythms of locomotor activity and feeding. European starlings (Sturnus vulgaris) were held in constant light (0.2 lux and 200 lux) and under constant temperature conditions. Locomotor activity was measured by means of perches with microswitches mounted underneath, and feeding with an infrared photocell system at the feeder. Pinealectomy consistently led to disturbances in perch-hopping rhythms and often to a complete loss of rhythmicity as revealed by periodogram analysis. In some birds, perch-hopping rhythms recovered following a period of initial arrhythmicity. When a perch-hopping rhythm was present, its period was usually shorter than it had been before pinealectomy. In contrast to its effects on perch hopping, pinealectomy had no effect on the persistence of feeding rhythmicity, although its period, like that of the hopping rhythm, decreased after this operation. These results support the hypothesis derived from previous studies that the circadian organization of feeding is different from that of perch hopping. Different circadian pacemakers may be involved, but other models may possibly explain the data just as well.

Animals↗