Palatability of stereoisomers and other amino acid derivatives to fish

Using a behavioral approach, it was shown that stereoisomers and other derivatives of amino acids (Ala, Glu, Gln; 0.1–0.01 М) have different palatability to fish (three-spined stickleback Gasterosteus aculeatus). The palatability of L-α-Ala is higher than of D-α-Ala or L-β-Ala, however, L-Glu and D-Glu equally increase the uptake of agar-agar pellets. L-Glu-Na has no stimulatory effect, probably, due to carnivorous feeding type in the three-spined stickleback. Palatabilities of L-Gln and L-Gln-HCl differ considerably. It is assumed that the influence of the configuration and structure of molecules on the palatability of amino acids to fish, as well as their taste preferences, are species-specific. The diversity of taste properties not only of L-, but also D-isomers of amino acids may matter in choosing adequate food objects in fish. Fish feeding behavior during oral sensory testing of artificial pellets, containing amino acids or their derivatives, obeys two alternative stereotypes, differing in the number of repeated manipulations with pellets and duration of the pellet retention time.     

Taste preferences and feeding behavior of three-spined stickleback Gasterosteus aculeatus of populations of basins of the Atlantic and Pacific oceans

The absence of population specificity of taste spectra in fish was confirmed. It was found that the three-spined stickleback Gasterosteus aculeatus of populations of the North (Norway), Baltic (Latvia), and Okhotsk (Kamchatka Peninsula) seas has similar taste preferences to classical taste substances (sodium chloride, calcium chloride, and sucrose—10%; citric acid—5%) and to 21 free amino acids (L-isomers, 0.1–0.001 M). For fish of all populations, glutamine, glutamic and aspartic acids, and alanine have the most attractive taste; cysteine, asparagine, and histidine have slightly less attractive taste. In Baltic Sea and Sea of Okhotsk sticklebacks, relatively not numerous amino acids that cause a significant decrease in pellet consumption—phenylalanine, tryptophane, leucine, and tyrosine—coincide (in the North Sea stickleback, substances with deterrent taste were not revealed). In sticklebacks of different populations, no differences in manifestation of feeding behavior were found, and correlations between different elements of fish response to pellets are similar or close the same. It was shown that intraoral sensory testing of food objects in three-spined stickleback can proceed along two alternative behavioral stereotypes similar in fish of the studied populations. The dependence of stereotypes of intraoral testing on taste qualities of the food object was revealed for the first time.     

Taste attractiveness of free amino acids for juveniles of Persian sturgeon <Emphasis Type="Italic">Acipenser persicus</Emphasis>

Taste preferences towards 20 free amino acids (L-isomers, 0.1–0.0001 M) were determined in juveniles of Persian sturgeon Acipenser persicus. It was found that most amino acids (16) had a positive effect on extraoral gustatory reception (increased the frequency of catching artificial pellets by fishes). The most efficient amino acids were the following: threonine, histidine, arginine, asparagine, phenylalanine, cysteine, glutamine, and glycine. Fifteen amino acids were efficient for intraoral gustatory receptors: serine, arginine, cysteine, histidine, alanine, and some others. The presence of these amino acids in pellets increased the consumption. Amino acids decreasing the frequency of catching or consumption of pellets were not found. Highly significant positive correlation was found between the amino acid ranges mediated by the extraoral and intraoral gustatory reception. The fishes demonstrated maximum sensitivity to aspartic acid, 0.01 and 0.001 M, respectively, for intraoral and extraoral gustatory systems. The threshold concentrations of arginine and glycine were higher for the intraoral gustatory system (0.01 M) than for the extraoral one (0.1 M). The comparison of Persian sturgeon with sturgeon fishes (Russian sturgeon A. gueldenstaedtii, Siberian sturgeon A, baerii, and starred sturgeon A. stellatus) studied earlier confirmed high species specificity of intraoral taste preferences in representatives of Acipenser genus. Species specificity of extraoral taste ranges was less pronounced.     

The distribution of an invasive fish species is highly affected by the presence of native fish species: evidence based on species distribution modelling

Topmouth gudgeon (Pseudorasbora parva) is one of the most invasive aquatic fish species in Europe and causes adverse effects to ecosystem structure and functioning. Knowledge and understanding of the species’ interactions with the environment and with native fish are important to stop and prevent the further spread of the species. Creating species distribution models is a useful technique to determine which factors influence the occurrence and abundance of a species. We applied three different modelling techniques: general additive models, random forests and fuzzy habitat suitability modelling (FHSM) to assess the habitat suitability of topmouth gudgeon. The former two techniques indicated that the abundance of native fish (i.e. biotic variables) was more important than environmental variables when determining the abundance of topmouth gudgeon in Flanders (Belgium). Bitterling (Rhodeus amarus), stone loach (Barbatula barbatula), three-spined stickleback (Gasterosteus aculeatus) and predator abundance were selected as the most important biotic variables and implemented in the FHSM to investigate species interactions. Depending on the preferred food source and spawning behaviour, either coexistence or interspecific competition can occur with bitterling, stone loach and three-spined stickleback. In contrast, the presence of predators clearly had a top down effect on topmouth gudgeon abundance. These findings could be applied as a biological control measure and implemented in conservation strategies in order to reduce the abundance of earlier established populations of topmouth gudgeon.     

Orosensory food testing in fish: Chronology of behavior

The orosensory food testing behavior in fish was studied using the nine-spined stickleback Pungitius pungitius as an example. The patterns of the chronology of manipulations performed by fish in testing food objects were identified. The existence of two stereotypical patterns of feeding behavior was confirmed, and their new characteristics were obtained. The relationship between the responsiveness to food and the predisposition of fish to feeding was revealed.     

Taste attractiveness of free amino acids and their physicochemical and biological properties (as exemplified by fishes)

Using fishes (32 species, 11 families) as an example, the relationship between the taste attractiveness of free amino acids (L-isomers) and their physicochemical and biological properties was analyzed. It was shown that essential amino acids, most nutritionally required for an organism, have lower taste attractiveness for fishes than nonessential amino acids. Only in 6 of the 32 tested species (sunbleak Leucaspius delineatus, European minnow Phoxinus phoxinus, dace Leuciscus leuciscus, chub Leuciscus cephalus, blue gourami Trichopodus trichopterus, pearl gourami Trichopodus leerii) the relationship between the taste attractiveness and molecular weight of amino acids was supported statistically, being negative in all cases. Only in 2 species, a statistically significant correlation between the taste properties of amino acids and the dissociation constant (K₁) was found, positive in the stone loach Barbatula barbatula and negative in the lake char Salvelinus namaycush. A positive correlation between taste preferences and the magnitude of the isoelectric point (pI) of amino acids was found in one species (roach Rutilus rutilus) and a negative correlation in 2 species (brown trout Salmo trutta and Arctic char Salvelinus alpinus erythrinus). A statistically significant correlation between the taste attractiveness and water solubility of amino acids was revealed in 2 species (chum salmon Oncorhynchus keta and navaga Eleginus nawaga), negative in both cases. The flavor, which stimulates food intake, was found to be more often intrinsic to acidic and polar uncharged than basic and nonpolar amino acids, L- than D-isomers, amino acids with an amino group at the α- than β-position. Amino acids are more attractive than their salts. Aromatic amino acids are much less attractive than S-containing or acyclic amino acids. Thus, in most fish species there is no or weak relationship between the taste attractiveness of free amino acids and many of their physical, chemical and biological properties, suggesting a mediated character of this relationship and/or its poor detectability.     

Parasite fauna in sticklebacks (Gasterosteidae) from bodies of water of the Kola region

The results of a parasitological study of the two species of sticklebacks (Pungitius pungitius and Gasterosteus aculeatus) inhabiting the Kola region are presented. The 42 and 14 species of parasite were found in the nine-spined and three-spined stickleback, respectively. The paucity of the parasite fauna in the three-spined stickleback is observed. Distribution of parasites in Kola waterbodies and ecological peculiarities in system "parasite-host" are presented.     

Life cycle and structure of populations of three-spined stickleback <Emphasis Type="Italic">Gasterosteus aculeatus</Emphasis> (Fam. Gasterosteidae) in rivers of northwestern Kamchatka (with reference to the Utkholok River)

From the end of May to mid-August 2005 and 2006, the dynamics of migrations and spawning, as well as specific features of development, growth, and feeding migration of the three-spined stickleback Gasterosteus aculeatus in the salmon river Utkholok of the mountain-tundra type were studied. Morphological characteristics, age, fecundity, dates of reproduction and spawning biotopes, structure of spawning groups, and specific features of feeding were investigated. On the basis of the obtained data, it was concluded that the riverine and migratory forms of three-spined sticklebacks from the Utkholok River belong to a single population. Biological specific features of spawners with high (2005) and low (2006) numbers of the migratory form were compared. For comparison, we also used our own data on the morphology and biological analysis of the migratory three-spined stickleback from the Kol River salmon of the mountain type.     

Activity of the Enzymes of the Energy and Carbohydrate Metabolism in the Organs of the Three-Spined Stickleback <Emphasis Type="Italic">Gasterosteus aculeatus</Emphasis> from Different Biotopes of the White Sea

The activity of the key enzymes of the energy and carbohydrate metabolism (cytochrome c oxidase, lactate dehydrogenase, aldolase, and glucose-6-phosphate dehydrogenase) have been studied in the three-spined stickleback Gasterosteus aculeatus spawning in different biotopes of the White Sea (Sel’dyanaya Bay, Sukhaya Salma Strait, and Kolyushkovaya Lagoon). It was found that individuals of stickleback from different spawning grounds differed mainly in the level of anaerobic metabolism and in the degree of utilization of carbohydrates during glycolysis. The results testify to the existence of adaptive mechanisms for the restructuring of the metabolic pathways of the energy metabolism depending on habitat conditions in different biotopes during the spawning period.     

Species assignment and population genetic studies of Gran Paraná pejerrey (<Emphasis Type="Italic">Odontesthes</Emphasis> sp., Atheriniformes,Atherinopsidae) from La Plata Basin in South America

Since 2013, the pelagic zone of Upper Lake Constance (ULC) has been subject to a massive invasion of the non-native three-spined stickleback (Gasterosteus aculeatus Linnaeus, 1758). Data from monthly monitoring of pelagic whitefish (Coregonus wartmanni Bloch, 1784) were used to compare weight-at-age and abundance of pelagic whitefish for years before (1997–2012) and after the invasion (2013–2015). Growth and abundance of pelagic whitefish is shown to be heavily influenced by stickleback presence. Mean autumn weight-at-age of whitefish decreased by 33.3% after the invasion took place and a significant decline in autumn CPUE in otherwise unfished cohorts of the population was also recorded. The results imply direct effects of stickleback presence on pelagic whitefish, including interspecific competition for food leading to reduced growth and survival, and predation of eggs and larvae, hampering recruitment. These observations coincide with a sharp decline in whitefish yield. In conclusion, this study shows that the invasion of stickleback has substantially altered the pelagic fish community of ULC, with severe consequences for commercial fisheries.     

Melt-in-Mouth Multi-particulate System for the Treatment of ADHD: A Convenient Platform for Pediatric Use

Generally, pellets obtained from extrusion/spheronization, containing microcrystalline cellulose (MCC), do not disintegrate. An attempt has been made to develop melt-in-mouth pellets of taste-masked atomoxetine hydrochloride, using extrusion-spheronization, for pediatric patients. Melt-in-mouth pellets were prepared using extrusion-spheronization method and optimized using 3³ FFD. MCC (X₁, %), mannitol (X₂, %) and Indion 414: Pharmaburst 500 ratio (X₃, ratio) were the factors (independent variables) studied, whereas responses studied (dependent variables) were friability (Y1, %), yield (Y2, %) shape (Y3, roundness) in vitro disintegration time (Y4, seconds). The optimized formulation obtained from FFD was characterized for friability, shape and morphology, in vitro disintegration time, porosity, moisture uptake, in vitro release study and in vivo taste and disintegration time in healthy human volunteers. Randomized, two-treatment, two-sequence, two-period, single dose, crossover sensory evaluation study of taste-masked melt-in-mouth pellet was carried out in 10 healthy human subjects. A statistically significant polynomial mathematical relationship was generated between the factors and responses to obtain an optimized formulation. The optimized formulation was characterized (in vitro and in vivo) and exhibited a rapid drug release in vitro attributed to fast disintegration of pellets and high solubility of drug in 0.1 N HCl and buffer (pH 6.8). In vivo, 40% of volunteers ranked taste-masked optimized formulation as slightly bitter while 60% ranked it as no taste. The optimized pellets were conveniently administered in volunteers and exhibited rapid in-vivo disintegration in the oral cavity. Melt-in-mouth pellets can be a used as a platform technology for administering drugs to paediatric patients accurately and conveniently resulting in patient compliance.     

Role of histamine as a putative inhibitory transmitter in the honeybee antennal lobe

Background

Nests are built in various animal taxa including fish. In systems with exclusive male parental care, the choice of a nest site may be an important component of male fitness. The nest site may influence male attractiveness as a mate, and male, embryo, and juvenile survival probabilities. Reproductively active three-spined stickleback males establish and defend a territory in which they build a nest. Territories can differ remarkably in qualities that influence male and female reproductive success like predation risk or abiotic factors such as dissolved oxygen concentration or lighting conditions. The latter may be important because in sticklebacks the extended visual capability into the ultraviolet (UV) wave range plays a role in female mate choice. Males are thus expected to be choosy about the habitat in which they will build their nest.

Results

We tested nest-site choice in male three-spined sticklebacks with respect to different UV lighting conditions. Reproductively active males were given the simultaneous choice to build their nest either in an UV-rich (UV+) or an UV-lacking (UV-) environment. Males exhibited no significant nest-site preferences with respect to UV+ or UV-. However, larger males and also heavier ones completed their nests earlier.

Conclusion

We found that UV radiation as well as differences in luminance had no influence on nest-site choice in three-spined sticklebacks. Males that built in the UV-rich environment were not different in any trait (body traits and UV reflection traits) from males that built in the UV-poor environment. There was a significant effect of standard length and body mass on the time elapsed until nest completion in the UV experiment. The larger and heavier a male, the faster he completed his nest. In the brightness control experiment there was a significant effect only of body mass on the duration of nest completion. Whether nest building preferences with respect to UV lighting conditions are context dependent needs to be tested for instance by nest-site choice experiment under increased predation risk.     

Biology of four sympatric sticklebacks in Cobscook Bay,Maine, a boreal,macrotidal bay

Four species of sticklebacks were collected during May, June, August, and September 2011–2013 in a survey of fishes of Cobscook Bay, a macrotidal bay in eastern Maine, U.S.A. Threespine (Gasterosteus aculeatus) and ninespine (Pungitius pungitius) sticklebacks have circumpolar distributions; blackspotted (Gasterosteus wheatlandi) and fourspine (Apeltes quadracus) sticklebacks are limited to northeastern North America. Sticklebacks were collected in the intertidal zone with beach seines and in the pelagic zone with trawls. Up to 30 individuals of each species from each sample were measured and weighed. Individuals were identified as gravid or not in 2012 and 2013. Catch-per-unit-efforts of the most abundant threespine (18,878 individuals) and second most abundant blackspotted sticklebacks (2433) were greatest in the innermost part of the bay, on mudflats, in 2012, and in August. Fewer than 100 fourspine and fewer than 50 ninespine sticklebacks were caught over the three years, mostly in the inner bay. Length-frequency distributions suggested age classes of 0+, 1+, 2+ and a few 3+ for threespine sticklebacks and 0+ and 1+ for blackspotted sticklebacks. Most gravid individuals of those two species were present in May and June. Spawning occurred earlier in 2012, an unusually warm year, than in 2013. Changes in presence, timing, and abundance of other species in the fish survey corroborated the influence of the record warm conditions in 2012 in the Gulf of Maine on the fish community of Cobscook Bay. Blackspotted and ninespine sticklebacks are vulnerable to population decline from warming in the Gulf of Maine because they are near the southern limits of distribution.     

Influence of Insecticides Diazinon and Endosulfan on Taste Reception in Persian Sturgeon <Emphasis Type="Italic">Acipenser persicus</Emphasis> (Acipenseridae)

The present paper studies the effects of sublethal concentrations of two neurotoxic insecticides (diazinon and endosulfan, duration of exposure 48 h) on the taste attractiveness of L-histidine (0.1 M), L-cysteine (0.1 M), and L-asparagine acid (0.01 M) for juvenile Persian sturgeon Acipenser persicus. The study revealed different effects of diazinon and endosulfan on the extraoral and intraoral taste reception in fish. The taste responses determined by the extraoral taste system (frequency of grasping of 50 food pellets for 5 min of trial) following exposure to endosulfan are the same as in the intact specimens. The exposure to diazinon leads to two to fourfold increase in the number of grasping the pellets, while the amino acids become tasteattractive as opposed to the intact specimens. Both insecticides affect the taste responses controlled by the intraoral taste reception. The insecticide-related pathology is expressed either as a sharp (tens of times) decrease in the absolute and relative consumption of all types of pellets or as full rejection of the pellets after their grasping. Furthermore, the intraoral taste properties of amino acids remain the same as in the intact fish.     

Rapid molecular sexing of three-spined sticklebacks, <Emphasis Type="Italic">Gasterosteus aculeatus</Emphasis> L., based on large Y-chromosomal insertions

There is a need for rapid and reliable molecular sexing of three-spined sticklebacks, Gasterosteus aculeatus, the supermodel species for evolutionary biology. A DNA region at the 5′ end of the sex-linked microsatellite Gac4202 was sequenced for the X chromosome of six females and the Y chromosome of five males from three populations. The Y chromosome contained two large insertions, which did not recombine with the phenotype of sex in a cross of 322 individuals. Genetic variation (SNPs and indels) within the insertions was smaller than on flanking DNA sequences. Three molecular PCR-based sex tests were developed, in which the first, the second or both insertions were covered. In five European populations (from DE, CH, NL, GB) of three-spined sticklebacks, tests with both insertions combined showed two clearly separated bands on agarose minigels in males and one band in females. The tests with the separate insertions gave similar results. Thus, the new molecular sexing method gave rapid and reliable results for sexing three-spined sticklebacks and is an improvement and/or alternative to existing methods.     

Fatty acid composition of fish species with different feeding habits from an Arctic Lake

We compared the composition and content of fatty acids (FAs) in fish with different feeding habits (sardine (least) cisco Coregonus sardinella, goggle-eyed charr (pucheglazka) form of Salvelinus alpinus complex, humpback whitefish Coregonus pidschian, broad whitefish Coregonus nasus, boganid charr Salvelinus boganidae, and northern pike Esox lucius from an Arctic Lake. Feeding habits of the studied fish (planktivore, benthivore, or piscivore) significantly affected the composition of biomarker fatty acids and the ratio of stable isotopes of carbon and nitrogen in their biomass. The hypothesis on a higher content of eicosapentaenoic and docosahexaenoic acids in the fish of higher trophic level (piscivores) when compared within the same taxonomic group (order Salmoniformes) was confirmed.     

Comparative Study of the Lateral-line System of the Three-spined Stickleback (Gasterosteus aculeatus) and the Nine-spined Stickleback (Pungitius pungitius)

Abstract The morphology of the lateral-line system of the nine-spined stickleback (Pungitius pungitius) and the three-spined stickleback (Gasterosteus aculeatus) has been studied. In the nine-spined stickleback, a preopercular, infraorbital, supraorbital, postotic and peduncular canal can be identified on both sides of the body. Replacement lines are found as a continuation of the preopercular and infraorbital canal. In addition, lines of free neuromasts are found on the mandible and trunk. An accessory line is present above and below the peduncular canal. The presence of both canals and accessory lines on the peduncle suggests that the peduncle in this species has important sensory functions. No canals are found in the three-spined stickleback. Instead, replacement lines corresponding to the canals can be identified on the head. Accordingly, the lateral-line system of the three-spined and the nine-spined stickleback has a different structure. The lateral-line system of both species shows signs of specialization but the three-spined stickleback has a more specialized lateral-line system than the nine-spined stickleback.     

Comparative study of the olfactory epithelium of the three-spined stickleback (Gasterosteus aculeatus) and the nine-spined stickleback (Pungitius pungitius)

Summary The olfactory epithelium of the three-spined stickleback (Gasterosteus aculeatus) and the nine-spined stickleback (Pungitius pungitius) has been studied with a conventional histochemical and a novel immunological staining technique. In both species, the sensory epithelium is arranged in folds separated by non-sensory epithelial tissue. In the nine-spined stickleback, intrinsic folds consisting of non-sensory cells are found in the apical part of the sensory epithelium where they divide the surface of the sensory epithelium into small islets. These non-sensory cells are non-ciliated, flattened and piled on top of each other; they contain numerous electron-translucent vesicles. The intrinsic folds are absent from the sensory epithelium of the three-spined stickleback. In both species, axons of receptor cells form a layer of fibers in the sensory epithelium immediately above the basal cells. In the three-spined stickleback, thick branches of the olfactory nerve are frequently found in this layer. These branches are only occasionally observed in the sensory epithelium of the nine-spined stickleback. Thus, the three-spined stickleback and the nine-spined stickleback show considerable differences in the organization of the sensory regions of the olfactory epithelium.     

The ultrastructure of the interstitial cells of the mesonephros in the teleost fishes of the Black Sea

The ultrastructure of cells that form mesonephros tissues in eight species of bony fish of the Black Sea, Gaidropsarus mediterraneus (L.), Lisa aurata (Risso), Trachurus mediterraneus (Staindachner), Diplodus annularis (L.), Spicara flexuosa (Rafinesque), Gobius niger jozo L., Mullus barbatus ponticus (Essipov) and Scorpaena porcus (L.), was studied. It was shown that the ultrastructure of agranulocytes and rodlet cells in the studied species is similar to that of cells in freshwater bony fish. The differences were observed in the number of ionocyte mitochondria, in the vesicle ultrastructure in the cells with radial vesicle array, and in the ultrastructure of the specific secondary granules of neutrophils and eosinophils.