Time-place learning in the cichlid angelfish, Pterophyllum scalare

The ability of the cichlid angelfish, Pterophyllum scalare, to associate time and place to locate food, provided twice a day in two different places, was tested. Food was delivered daily in one corner of the tank in the morning and in the diagonally opposite corner in the afternoon, for a 3-week period, and the distribution of the fish in the tank was noted prior to and during feeding time. The results indicate that, in a fairly uniform environment and in the absence of external time cues, angelfish can discriminate and associate time and place to obtain a food reward. It is suggested that they do so by means of an endogenous timing mechanism.     

Towards an isolation syndrome for the angelfish, Pterophyllum scalare

The behaviour of individual angelfish, Pterophyllum scalare , isolated for 4 days in the laboratory has been compared with that of the same fish in groups. Locomotor activity, feeding behaviour, aggression and responses to novel stimuli have been studied. Isolated fish are less active, approach the surface to feed less readily and are slower to recover from sudden mechanical shock than when kept in a group. In contrast, isolates are more attentive to a gradually-applied, novel, visual stimulus. The aggressive behaviour of post-isolates on return to the group tank was not significantly different from that shown before isolation.     

Fine structure of nerve-melanophore contacts in the angelfish Pterophyllum scalare

Contacts between small unmyelinated nerve fibres and dermal melanophores of the angelfish, Pterophyllum scalare, exhibit several features characteristic of synapses, including small synaptic vesicles and dense core vesicles, a narrow synaptic cleft, electron-dense material at the postsynaptic membrane (cell membrane of the melanophore) and, occasionally, presynaptic densities. An analysis of serial thin sections shows that the synapses described here represent varicosities of an otherwise more or less straight nerve fibre. A single axon thereby may form several en passant synapses with a single melanophore. It is suggested that the synaptic contacts described here not only represent sites of transmitter release but also play a role as sites of firm attachment between nerves and melanophores which guarantee a stable arrangement of nerve fibres and melanophores.Supported by the Deutsche Forschungsgemeinschaft     

A new fish cell line derived from the caudal fin of freshwater angelfish Pterophyllum scalare: development and characterization

In this study, a new cell line derived from the caudal fin of the freshwater angelfish Pterophyllum scalare was developed and characterized. The cell line was designated angelfish fin (AFF) and subcultured 44 times since its development. These cells grew well in Leibovitz's ?15 medium supplemented with 10% foetal bovine saline (FBS) at 28° C and the modal chromosome number (2n) was 48. The AFF cell‐line is mainly comprised of epithelial cells as confirmed by immunocytological technique using anti‐cytokeratin antibodies, an epithelial cell marker. This cell line was tested for growth in a temperatures range from 20 to 37° C and at various FBS concentrations of 5–20% at 28° C. The cell line was cryopreserved at different passage levels and revived successfully with 80% survival rate. Polymerase chain reaction amplification and sequencing of partial mitochondrial 16s rRNA and coI genes confirmed that the AFF cell‐line originated from angelfish. Mycoplasma sp. contamination was not detected in AFF cells and checked by Hoechst 33258 fluorescence staining. At the 42nd passage the cells were transfected with 2 μg of pAcGFP1‐N1 expression vector. The AFF cells exhibited cytotoxic effects when exposed to the bacterial extra cellular products from Serratia marcescens and Proteus hauseri. The AFF cells and cells from kidney and brain did not show cytopathic effect when exposed to cyprinid herpes virus2 and viral nervous necrosis virus. The newly developed AFF cell line will be useful for the isolation of viruses affecting angelfishes, such as iridoviruses, in the future.     

Haemopoietic centres in the developing angelfish,Pterophyllum scalare (cuvier and valenciennes)

Summary The first haemopoietic centres in the embryo ofPterophyllum scalare are found in the blood islands of the yolk sac. These results are in contrast to the classical theory of blood formation in teleosts, which maintains that the first blood formation occurs intraembryonically, in the so-called intermediate cell mass of Oellacher. InPterophyllum, the intermediate cell mass forms only the axial blood vessels. Haemopoiesis in the post-embryo is carried out by the pronephros. This organ remains haemopoietic to the adult stage. In the adult, the pronephric tubules are degenerated; the organ is filled with haemopoietic tissue and also contains strands of adrenal tissue. The adult kidney (mesonephros) is also haemopoietic, though to a much lesser degree than the pronephros.The blood islands in the yolk sac form only stem cells (haemocytoblasts) and proerythroblasts. Released into the circulation, they differentiate and mature into round, disc-like erythrocytes (erythrocytes-E). Erythropoiesis in the pronephros produces elliptical erythrocytes (erythrocytes-ImA). Thus for the latter part of the postembryonic phase, until complete absorption of the yolk, there is a mixed erythrocyte population in circulation. During metamorphosis into the laterally-compressed adult, the adult type of erythrocyte (erythrocyte-A) makes its first appearance. Leucocytes and thrombocytes appear much later in development than the red blood cells. They are formed in the pronephros and are seen in circulation only after the yolk has been absorbed.     

Observations on rodlet cells found in the vascular system and extravascular space of angelfish (Pterophyllum scalare scalare)

In the angelfish ( Pterophyllum scalare scalare ) numerous rodlet cells were found in the large post-orbital blood vessel caudal to the eye and in the surrounding extravascular space. Within the vessel the rodlet cells formed striking regular arrays, along the inner aspect of the wall. The rodlets within the cells were positive to PAS but negative to Sudan Black B, Masson's, and the Fuelgen stain. The capsule around the cells was negative for all these stains. These rodlet cells appeared to be traversing the vessel endothelium, and to be pushing the endothelium aside without damaging it. Some discharged their contents into the vessel, but we never observed the release of intact rodlets. The nuclei of rodlet cells in actual contact with the vessel were at the end of the cell more distant from the endothelial wall. Cell-to-cell adhesion structures or communications junctions between rodlet cells and the endothelium were not evident. A putative rodlet cell precursor in the extravascular space contained large electron-dense granules, and extended pseudopodia that contacted nearby rodlet cells. Based on their morphology, tissue distribution, and their behaviour, we conclude that the rodlet cell is an endogeneous teleost cell type, and possibly represents a form of matured granulocyte.     

Brief communication: Morphological effects of captivity: A geometric morphometric analysis of the dorsal side of the scapula in captive‐bred and wild‐caught hominoidea

Many osteological collections from museums and research institutions consist mainly of remains from captive‐bred animals. The restrictions related to the space of their enclosures and the nature of its substrate are likely to affect the locomotor and postural behaviors of captive‐bred animals, which are widely considered uninformative regarding bone morphology and anatomical adaptations of wild animals, especially so in the case of extant great apes. We made a landmark‐based geometric morphometrics analysis of the dorsal side of the scapular bone of both wild‐caught and captive‐bred great apes to clarify the effect of captivity on the morphology of a bone greatly involved in locomotion. The comparison suggested that captivity did not have a significant effect on the landmark configuration used, neither on average scapular shape nor shape variability, being impossible to distinguish the scapulae of a captive‐bred animal from that of a wild‐caught one. This indicates that the analyzed scapulae from captive Hominoidea specimens may be used in morphological or taxonomic analyses since they show no atypical morphological traits caused by living conditions in captivity. Am J Phys Anthropol 152:306–310, 2013. © 2013 Wiley Periodicals, Inc.     

The influence of social rank in the angelfish,Pterophyllum scalare,on locomotor and feeding activities in a novel environment

To investigate differences in behaviour associated with social rank and environmental conditions, a comparison was made between swimming and feeding activities of dominant and subordinate angelfish, housed in groups of six, with those of angelfish housed singly in identical laboratory aquaria. Subordinate individuals were less active, less ready to feed and consumed less food items than dominants, but their feeding and activity levels were still greater than those displayed by isolated fish used as controls. When fish from each of the above categories were transferred to a novel, identical tank to be tested individually for a 6-day period, little change was observed in previously isolated fish. In contrast, the previous social experience had a marked influence on the behaviour of the other individuals, the effects being related to the social status. The strongest initial response to the new environment was shown by subordinate individuals, with a significant increase in swimming and a significant decrease in feeding compared to the group situation. Subordinates were significantly more active than dominants, who in turn moved more than previously isolated fish. Dominants and subordinates were now similarly reluctant to feed, and their food consumption was less than that of previously isolated fish. With time in the novel environment a significant reduction of swimming activity and a recovery of feeding measures were detected, but levels were still depressed in relation to the group condition, and lower in subordinates than in dominants, indicating the long-lasting effects of the previous social interactions. The results have clear implications for laboratory studies using groups of fish in which social hierarchies may be established prior to individuals being tested singly in a novel environment.     

Fatty acid composition,cholesterol and fat‐soluble vitamins of wild‐caught freshwater spiny eel,Mastacembelus simack (Walbaum, 1792)

Because of its local commercial value, the proximate nutritional composition, fatty acid composition, cholesterol and fat‐soluble vitamins of spiny eel (Mastacembelus simack Walbaum, 1792) were determined in 20 specimens caught in Keban Dam Lake, Elaz??, Turkey in September 2009. Moisture, protein, lipid, ash and cholesterol contents of the spiny eel were 75.9, 17.1, 10.9, 1.0% and 52.6 mg per 100 g, respectively. Fatty acid composition showed that total polyunsaturated fatty acids (PUFA) were the highest (37.1%), followed by monounsaturated fatty acids (MUFA, 35.5%) and saturated fatty acids (SFA, 27.4%). The relation between PUFA and SFA (1.35) was comparable to that of some fish species, and PUFA : MUFA : SFA ratio (1.35 : 1.29 : 1) was very close to that recommended by nutritionists. Among the vitamins (A, D, E and K) analyzed, the vitamin E content was highest followed by D, K and A. In conclusion, M. simack is rich in proteins, unsaturated fatty acids and vitamins and low in cholesterol, with a reasonable PUFA : SFA and PUFA : MUFA : SFA ratio as recommended by nutritionists. M. simack can therefore be recommended for human consumption as a good source of nutrition.     

Critical swimming speeds of wild‐caught sand‐smelt Atherina presbyter larvae

Swimming abilities of wild‐caught sand‐smelt Atherina presbyter larvae were assessed as critical swimming speed (U_crit) throughout ontogeny. The mean U_crit increased with size, ranging from 3·6 to 18·7 cm s^?1, over the size range of 6·6–21·0 mm L_T. This indicates that at hatching A. presbyter larvae, far from being passive floaters, are already capable of active behaviours, which may influence their dispersal patterns.     

Comparative migration strategies of wild and captive‐bred Asian Houbara Chlamydotis macqueenii

For migratory species, the success of population reintroduction or reinforcement through captive‐bred released individuals depends on survivors undertaking appropriate migrations. We assess whether captive‐bred Asian Houbara Chlamydotis macqueenii from a breeding programme established with locally sourced individuals and released into suitable habitat during spring or summer undertake similar migrations to those of wild birds. Using satellite telemetry, we compare the migrations of 29 captive‐bred juveniles, 10 wild juveniles and 39 wild adults (including three birds first tracked as juveniles), examining migratory propensity (proportion migrating), timing, direction, stopover duration and frequency, efficiency (route deviation), and wintering and breeding season locations. Captive‐bred birds initiated autumn migration an average of 20.6 (±4.6 se) days later and wintered 470.8 km (±76.4) closer to the breeding grounds, mainly in Turkmenistan, northern Iran and Afghanistan, than wild birds, which migrated 1217.8 km (±76.4), predominantly wintering in southern Iran and Pakistan (juveniles and adults were similar). Wintering locations of four surviving captive‐bred birds were similar in subsequent years (median distance to first wintering site = 70.8 km, range 6.56–221.6 km), suggesting that individual captive‐bred birds (but not necessarily their progeny) remain faithful to their first wintering latitude. The migratory performance of captive‐bred birds was otherwise similar to that of wild juveniles. Although the long‐term fitness consequences for captive‐bred birds establishing wintering sites at the northern edge of those occupied by wild birds remain to be quantified, it is clear that the pattern of wild migrations established by long‐term selection is not replicated. If the shorter migration distance of young captive‐bred birds has a physiological rather than a genetic basis, then their progeny may still exhibit wild‐type migration. However, as there is a considerable genetic component to migration, captive breeding management must respect migratory population structure as well as natal and release‐site fidelity.     

Processing yield of wild‐caught and indoor‐reared Brazilian flounder Paralichthys orbignyanus

The aims of this work were to evaluate the fillet yield and the skin area production of wild‐caught (male × female) and indoor‐reared male Brazilian flounder Paralichthys orbignyanus. Fillet yield of wild‐caught Brazilian flounder is high, averaging 53.4 ± 0.7 and 51.2 ± 0.6% to female and male, respectively. However, indoor‐reared male flounder show even higher (P < 0.05) fillet yields of 59.4 ± 0.1%. Flounder weighing around 500 g should yield a skin area of ca. 450 cm², representing an important sub‐product that can be used in the fashion industry. The results of the present study emphasize the potential for culture and use of sub‐products of the Brazilian flounder.     

Mating system of the Amazonian cichlid angel fish, Pterophyllum scalare.

The species, Pterophyllum scalare distinguishes itself by its breeding behavior, involving competition for territory, sexual partners, courtship and parental care. The purpose of this study was to identify the mating system adopted by this species of fish. Twenty males and twenty females were observed under semi-natural and experimental conditions to test the hypothesis of serial monogamy. Under semi-natural conditions, after the third breeding cycle, the couples changed mates. Under experimental conditions, the couples changed partners after the first breeding cycle. Under experimental conditions, mate recognition was investigated through the preference of the females, indicated by the time they spent with the males. The females were available or not for courtship from new males, depending on their aggressiveness or submission. The larger and more aggressive males obtained new mating opportunities while the submissive males were rejected by the females. The mated fish were aggressive towards intruders in the presence of the mate, protecting their pair bond. In the interval between breeding cycles, the couples did not display aggression towards intruders, confirming the hypothesis of serial monogamy. Best mate selection by the females and the opportunity of new matings for both sexes influenced the reproductive success of this species.     

Survival rates of captive‐bred Asian Houbara Chlamydotis macqueenii in a hunted migratory population

Asian Houbara Chlamydotis macqueenii numbers are declining as a result of unsustainable levels of hunting and poaching, with the main conservation response being population reinforcement through the release of captive‐bred birds. We assessed the contribution of captive breeding to the species’ conservation by examining the fates of 65 captive‐bred birds fitted with satellite transmitters and released during spring (March–May) and autumn (August) into breeding habitat in Uzbekistan. Of the released birds, 58.5% survived to October, the month favoured by Emirati hunters in Uzbekistan, but only 10.8% of those released survived the winter to return as subadults next spring. To mitigate and compensate for the loss of wild adults to hunting, the number of released birds needs to be an order of magnitude higher than hunting quotas (with a release of between 1640 and 1920 required for a hypothetical quota of 200), indicating that releases may be costly and do not remove the need for a biologically determined sustainable hunting quota.     

Reproductive and post‐reproductive life history of wild‐caught Drosophila melanogaster under laboratory conditions

The life history of the fruit fly (Drosophila melanogaster) is well understood, but fitness components are rarely measured by following single individuals over their lifetime, thereby limiting insights into lifetime reproductive success, reproductive senescence and post‐reproductive lifespan. Moreover, most studies have examined long‐established laboratory strains rather than freshly caught individuals and may thus be confounded by adaptation to laboratory culture, inbreeding or mutation accumulation. Here, we have followed the life histories of individual females from three recently caught, non‐laboratory‐adapted wild populations of D. melanogaster. Populations varied in a number of life‐history traits, including ovariole number, fecundity, hatchability and lifespan. To describe individual patterns of age‐specific fecundity, we developed a new model that allowed us to distinguish four phases during a female's life: a phase of reproductive maturation, followed by a period of linear and then exponential decline in fecundity and, finally, a post‐ovipository period. Individual females exhibited clear‐cut fecundity peaks, which contrasts with previous analyses, and post‐peak levels of fecundity declined independently of how long females lived. Notably, females had a pronounced post‐reproductive lifespan, which on average made up 40% of total lifespan. Post‐reproductive lifespan did not differ among populations and was not correlated with reproductive fitness components, supporting the hypothesis that this period is a highly variable, random ‘add‐on’ at the end of reproductive life rather than a correlate of selection on reproductive fitness. Most life‐history traits were positively correlated, a pattern that might be due to genotype by environment interactions when wild flies are brought into a novel laboratory environment but that is unlikely explained by inbreeding or positive mutational covariance caused by mutation accumulation.     

Identifying homomorphic sex chromosomes from wild‐caught adults with limited genomic resources

We demonstrate a genotyping‐by‐sequencing approach to identify homomorphic sex chromosomes and their homolog in a distantly related reference genome, based on noninvasive sampling of wild‐caught individuals, in the moor frog Rana arvalis. Double‐digest RADseq libraries were generated using buccal swabs from 30 males and 21 females from the same population. Search for sex‐limited markers from the unfiltered data set (411 446 RAD tags) was more successful than searches from a filtered data set (33 073 RAD tags) for markers showing sex differences in heterozygosity or in allele frequencies. Altogether, we obtained 292 putatively sex‐linked RAD loci, 98% of which point to male heterogamety. We could map 15 of them to the Xenopus tropicalis genome, all but one on chromosome pair 1, which seems regularly co‐opted for sex determination among amphibians. The most efficient mapping strategy was a three‐step hierarchical approach, where R. arvalis reads were first mapped to a low‐coverage genome of Rana temporaria (17 My divergence), then the R. temporaria scaffolds to the Nanorana parkeri genome (90 My divergence), and finally the N. parkeri scaffolds to the X. tropicalis genome (210 My). We validated our conclusions with PCR primers amplifying part of Dmrt1, a candidate sex determination gene mapping to chromosome 1: a sex‐diagnostic allele was present in all 30 males but in none of the 21 females. Our approach is likely to be productive in many situations where biological samples and/or genomic resources are limited.