Cytogenetic analysis of three sympatric Gymnotus (Gymnotiformes, Gymnotidae) species verifies invasive species in the Upper Paraná River basin, Brazil

Cytogenetic analyses were performed on three Gymnotus species, Gymnotus paraguensis , Gymnotus sylvius and Gymnotus pantanal , collected in sympatry in the region of Guaíra, Paraná State (Brazil). Gymnotus paraguensis presented 54 chromosomes (52m-sm + 2st) in both sexes, G. sylvius presented 40 chromosomes (36m-sm + 4a) in both sexes and G. pantanal presented 40 chromosomes (14m-sm + 26a) in females and 39 (15m-sm + 24a) in males, with an X₁X₁X₂X₂/X₁X₂Y multiple sex chromosome system. All three species had single nucleolar organizing regions and heterochromatin in the centromeric region of most chromosomes. Gymnotus pantanal , previously collected only in the Lower Paraná and Paraguay River basins, was confirmed for the first time in the Upper Paraná River basin. This species constitutes one of several examples of species that have colonized the region after flooding of the great Sete Quedas waterfalls by the construction of the Itaipu hydroelectric dam. The probable absence or infertility of hybrids is indicated by the high level of chromosome differentiation between these species.     

Species-specific diversity of a fixed motor pattern: the electric organ discharge of Gymnotus

Understanding fixed motor pattern diversity across related species provides a window for exploring the evolution of their underlying neural mechanisms. The electric organ discharges of weakly electric fishes offer several advantages as paradigmatic models for investigating how a neural decision is transformed into a spatiotemporal pattern of action. Here, we compared the far fields, the near fields and the electromotive force patterns generated by three species of the pulse generating New World gymnotiform genus Gymnotus. We found a common pattern in electromotive force, with the far field and near field diversity determined by variations in amplitude, duration, and the degree of synchronization of the different components of the electric organ discharges. While the rostral regions of the three species generate similar profiles of electromotive force and local fields, most of the species-specific differences are generated in the main body and tail regions of the fish. This causes that the waveform of the field is highly site dependant in all the studied species. These findings support a hypothesis of the relative separation of the electrolocation and communication carriers. The presence of early head negative waves in the rostral region, a species-dependent early positive wave at the caudal region, and the different relationship between the late negative peak and the main positive peak suggest three points of lability in the evolution of the electrogenic system: a) the variously timed neuronal inputs to different groups of electrocytes; b) the appearance of both rostrally and caudally innervated electrocytes, and c) changes in the responsiveness of the electrocyte membrane.     

Ethology of Hygienic Behaviour in the Honey Bee Apis mellifera L. (Hymenoptera: Apidae): Behavioural repertoire of Hygienic bees

Hygienic behaviour performed by middle‐aged worker bees is an important intranidal task in colonies of the honey bee Apis mellifera (L.). It comprises detecting diseased brood in the larval and pupal stages and removing all such infected brood, thereby decreasing the incidence of infection. Hygienic behaviour consists of two task‐components: uncapping cells and removing the cell contents. The aim of this study was to observe bees performing hygienic behaviour to determine their age at performance of the behaviour and to describe their behavioural repertoire. The bees performing hygienic behaviour were middle‐aged bees, younger than foragers. In the colonies where the behaviours of individual bees were observed, all bees performing the hygienic behaviour were seen to exhibit both the components, though at different frequencies. One behavioural class performed the task of uncapping cells at higher frequencies than the task of removing cell contents, while another class performed both tasks to the same extent. While these two classes had higher frequencies of the tasks comprising the hygienic behaviour but lower frequencies of other common behaviours in their repertoire, a third class of bees included those that performed all behaviours in their repertoire at similar frequencies. There was no difference in the ages of the bees in these three behavioural classes. These results suggest that there is no evidence of task partitioning among bees performing the hygienic behaviour. The segregation observed could, however, be based on their response thresholds to the stimulus and/or on their ability to discriminate the various cues emanating from the dead brood.     

Life history of <Emphasis Type="Italic">Gymnotus refugio</Emphasis> (Gymnotiformes; Gymnotidae): an endangered species of weakly electric fish

The present study describes the life history of Gymnotus refugio, a species classified as Endangered in the last published list of threatened species of the Brazilian fauna. The study was conducted at a conservation unity that protect one of the last remaining semideciduous forests in the region. The reproductive period was estimated as occurring from the end of winter to the last summer months. Gymnotus refugio exibited fractional spawning, the lowest relative fecundity registered among the Gymnotifomes species studied at the present, and male parental care behavior. The analyses showed a seasonal pattern on the species diet, associating different food categories to winter, autumn, and spring. According to food items analysis and estimated intestinal quotient, G. refugio was classified as invertivorous, feeding mainly on autochthonous insects. The results obtained herein suggest that the position of G. refugio as an Endangered species might be influenced by its territoriality, habitat specificity, parental care behavior, and low fecundity, reinforcing the importance of swampy forest environment conservation as the only means of the species maintenance.     

Motor representation of actions in children with autism

Background

Children with Autistic Spectrum Disorders (ASD) are frequently hampered by motor impairment, with difficulties ranging from imitation of actions to recognition of motor intentions. Such a widespread inefficiency of the motor system is likely to interfere on the ontogeny of both motor planning and understanding of the goals of actions, thus delivering its ultimate effects on the emergence of social cognition.

Methodology/Principal Findings

We investigate the organization of action representation in 15 high functioning ASD (mean age: 8.11) and in two control samples of typically developing (TD) children: the first one, from a primary school, was matched for chronological age (CA), the second one, from a kindergarten, comprised children of much younger age (CY). We used nine newly designed behavioural motor tasks, aiming at exploring three domains of motor cognition: 1) imitation of actions, 2) production of pantomimes, and 3) comprehension of pantomimes. The findings reveal that ASD children fare significantly worse than the two control samples in each of the inspected components of the motor representation of actions, be it the imitation of gestures, the self-planning of pantomimes, or the (verbal) comprehension of observed pantomimes. In the latter task, owing to its cognitive complexity, ASD children come close to the younger TD children’s level of performance; yet they fare significantly worse with respect to their age-mate controls. Overall, ASD children reveal a profound damage to the mechanisms that control both production and pre-cognitive “comprehension” of the motor representation of actions.

Conclusions/Significance

Our findings suggest that many of the social cognitive impairments manifested by ASD individuals are likely rooted in their incapacity to assemble and directly grasp the intrinsic goal-related organization of motor behaviour. Such impairment of motor cognition might be partly due to an early damage of the Mirror Neuron Mechanism (MNM).     

Congruence of electrical properties in two Antarctic and two middle-latitude marine species of Euplotes (Ciliata, Hypotrichida)

Electric membrane properties and motor behaviour of two Antarctic and two middle-latitude species of Euplotes were compared. Membrane potential fluctuations and whole-cell currents were measured using the whole cell clamp. The electrical properties of both of the Antarctic species between themselves and of both of the middle-latitude species are nearly identical. Furthermore, after warming up to 22°C, the Antarctic species grown at 4°C show the same pattern of spontaneous potential fluctuations, induced potential oscillations and membrane currents as the middle-latitude species grown and measured at 22°C. After cooling down to 4°C, the middle-latitude species grown at 22°C show the same electrical properties as the Antarctic species grown and measured at 4°C. The congruence of the temperature-dependent electrical properties in Euplotes species from completely different habitats is presumably based on a universal mechanism of temperature dependence of ionic conductances, indicating the close physiological relationship among the species. Received: 29 October 1997 / Accepted: 20 April 1998     

Comparative study of vocal communication in two Asian leaf monkeys, Presbytis johnii and Presbytis entellus

This paper presents comparative data on the vocal communication of two Asian leaf monkeys, the Nilgiri langur (Presbytis johnii) and South Indian common langur (Presbytis entellus), based on sound recordings and behavioural observations of free-ranging groups. Spectrographical analyses revealed a repertoire of 18 basic patterns for Nilgiri langurs, and 21 basic patterns for common langurs. The repertoires of the two langur species consist of both discretely structured vocal patterns, in which alterations of the physical parameters are restricted to intra-class variation, and those in which structural variations cause integration between different sections of the repertoire. Qualitative assessments of group scans indicate that in both species vocal behaviour is characterized by pronounced sex-differences in the use of the different elements of the vocal repertoire. Comparison of data available from different populations of P. entellus suggests population-specific modifications on both structural and behavioural levels. Moreover, characteristic elements of the vocal systems of the two Asian species demonstrate striking similarities to those described for the African black-and-white colobus.     

A statistical analysis of the functional connections between the neurons of the visual and motor cortex in different forms of conditioned-reflex behavior]

In experiments on cats with elaboration of delayed alimentary operant reflexes to light organization was studied of interneuronal cortical connections. By means of cross-correlation analysis the dynamics of intra- and interstructural neuronal network was revealed at the level of cortical projections (visual and motor) of cats brain zones at three forms of behaviour: CR realization, in intersignal period with the presence and absence of operant movements. Depending on the forms of behaviour, predominance of "informational" or "motivational" interneuronal connections was observed.     

Innervation pattern and electric organ discharge waveform in Gymnotus carapo (Teleostei; Gymnotiformes)

The electrogenic organ (EO) of Gymnotus carapo has two main portions: a posterior region consisting of four bilaterally arranged electrocyte rows; and an anterior portion composed of only two. The lateral row (LR) of the anterior portion contains doubly innervated electrocytes with axon terminals from different nerves on their rostral and caudal faces. The LR is continuous with the most dorsal row of the caudal region. This row also contains doubly innervated electrocytes. The medial row (MR) electrocytes of the anterior region and ventral rows of the caudal region are exclusively caudally innervated. All caudal faces of the anterior or abdominal region are supplied by two nerves which originate from spinal roots VIII to XXI. Roots I to VII give origin to pure rostral nerves whose electromotor axons terminate on the rostral surfaces of the first seven LR electrocytes. A given doubly innervated electrocyte is supplied on its caudal face by a nerve originating several segments (usually seven) posterior to the spinal root supplying its rostral face. Transections of the spinal cord at the level of root VIII isolate the activity of the rostral surfaces of the first electrocytes. The EO discharge (EOD) then appears as a head negative deflection which arises from abdominally located electrocytes. Its monophasic character reveals that the activity remains restricted to the rostral electrocyte surfaces. Damage of the abdominal portion of the EO abolishes the first negative deflection of the normal pulse. Transections of the spinal cord at the level of root XXI isolate the activity of the whole abdominal portion of the EO. Since both doubly and singly innervated electrocytes remain active, the EOD appears biphasic. Comparative studies have shown that the EOD of Hypopomus sp. lacks any early negative wave and correspondingly all its electrocytes are exclusively caudally innervated.     

Innate differences in singing behaviour of sparrows reared in isolation from adult conspecific song

Innate differences in the singing behaviour of male swamp (Melospiza georgiana) and song (M. melodia) sparrows were identified by rearing males from the egg in the laboratory under identical conditions, in complete isolation from adult conspecific song. Isolation-reared males of both species displayed several abnormal song features, including reduced numbers of notes per song, longer durations of notes and inter-note intervals, and fewer notes per syllable. Despite these and other abnormalities, many species differences emerged that matched differences in the natural singing behaviour of the two species. These included differences in song repertoire size, song duration and degrees of segmentation, numbers of notes per song, durations of notes and inter-note intervals, and several measures reflecting the organization of songs into note complexes, syllables and trills. Although learning can influence all levels of organization of the motor patterns of song in swamp and song sparrows, its contribution to the achievement of normal song behaviour appears to be most crucial at the level of the fine structure of the notes and syllables from which the songs are constructed.     

Antigenic analysis of three strains of Mycoplasma arginini by two-dimensional immunoelectrophoresis.

The occurrence of species-specific and strain-specific antigens in three strains of Mycoplasma arginini (G-230, leonis and 23243) was studied by two-dimensional immunoelectrophoresis. Approximately 20 antigenic components could be detected in each strain. It was possible to analyze 6 to 7 major and distinct components from each strain by two techniques: "enhancement" where antigen to an additional strain is added to the first phase of the electrophoresis which increases the size of common peaks and "suppression" where antiserum to an additional strain is incorporated in the second phase whereby peak size of components to which both sera have antibody are decreased. A total of 10 distinct antigens were recognized. Electrophoretic mobilities relative to bovine albumin ranged from 0.2 to 1.08. Three components were common to all strains; two of these represented major amounts of material. Four components represented strain-specific components. Unique fast components were found both in strains 23243 and G-230. Three antigens were distributed into only two of the three strains. The electrophoretic mobilities of some common antigens were quite different between strains.     

Factor analysis of rat behavior in the open-field test

Method of major components, a variety of factor analysis, was used for evaluation of rats behaviour motivational structure in the open field test. 40 outbred rats of Wistar line (20 males and females) were examined in which 22 behaviour characteristics were studied. It was shown that a greater part (60%) of rats individual behaviour variability in the open field test was determined by the action of three major components (factors), which were defined as "investigation", "fear" and "shifted activity". Factor structure was studied of main characteristics of behaviour, recorded in the open field test. The use of factor analysis allowed to carry out animals classification on the basis of their disposition in coordinates of the obtained major components.     

VOCAL REPERTOIRE OF WILD BREEDING ORANGE-WINGED PARROTS AMAZONA AMAZONICA IN AMAZONIA

ABSTRACT

The vocal repertoire of Amazona amazonica during its breeding season has been recorded from wild individuals in Santa Bárbara do Pará, Pará State, Brazil. At individual nests, we continuously recorded vocalizations and behaviour for four hours in the early morning and three hours in the late afternoon, three times a week throughout the breeding season. We identified nine vocalizations that we classified in three behavioural categories: (1) Flight call—emitted when parrots arrive in the nest area; (2) Perched contact calls—two different vocalizations, one of them related to feeding, were emitted when the pair was perched in the nest area and interacted socially between themselves or with other individuals; (3) Aggressive calls—emitted when birds were in a dangerous situation, i.e. alarm (three types of calls), agonistic contact and distress calls (two types of call). The Orange-winged Parrot is a highly social species and the complexity of its social interactions is reflected in the diversity of its vocal repertoire.     

Probability analysis of elements of rat behavior after sudden and signalled interruption of food reinforcement

Probability analysis was carried out of the appearance of single elements of rats behaviour in the process of extinction of a conditioned alimentary motor reflex. The dynamics of effector behavioural components at a sudden cessation of reinforcement (usual schedule of extinction) was compared with cessation of reinforcement signalled by a previously differentiated signal and with reinforcement cessation preceded by a stimulus initially unknown to the animal. If the reinforcement cessation is signalled by a previously differentiated (negative) stimulus, in response to its action the animals "loose the aim", what is revealed in a rapid complete reduction of all elements of the goal-directed alimentary behaviour. Obviously differentiation signal actualises the memory trace of "nonreinforcement" which was formed in the previous negative experience of the animal; this is revealed in accelerated inhibition of the alimentary motor reflex under extinction.     

The nature of controlled respiration and its relationship to protonmotive force and proton conductance in blowfly flight-muscle mitochondria

1. To determine whether controlled (State 4) pyruvate oxidation can support a high energy state, measurements of the redox span NAD-cytochrome c, phosphorylation potential and protonmotive force (the gradient in electrochemical activity of protons across the mitochondrial inner membrane) were made as indices of energy status. For comparison, these three measurements were also made with glycerol 3-phosphate, an alternative substrate. The two substrates gave essentially identical values for the redox span NAD-cytochrome c in State 4, and the phosphorylation potential was of sufficient magnitude to be considered in equilibrium with the redox span over the first two phosphorylation sites. The magnitude of the protonmotive force in State 4 was much less and the implications of this finding are discussed. 2. Measurements made during the controlled (State 4) to active (State 3) transition indicated that with glycerol 3-phosphate as substrate, both the redox span NAD-cytochrome c and the protonmotive force were diminished; the State 4 --> State 3 transition with pyruvate as substrate was accompanied by an increase in the redox span but a decrease in protonmotive force. The contrary behaviour of these two energetic parameters in the presence of pyruvate was ascribed to a transient excess in the flux of protons through the adenosine triphosphatase relative to the protonpumping respiratory chain, in spite of the increased dehydrogenase activity. 3. The lower protonmotive force seen in State 3 relative to State 4 with pyruvate as substrate was due to a diminution of both the electrical (DeltaPsi) and the chemical (DeltapH) components; with glycerol 3-phosphate, the magnitude of the decrease in protonmotive force during the State 4 --> State 3 transition was similar to that seen with pyruvate, but was due to a large decrease in the electrical component (DeltaPsi) and a small rise in the chemical component (DeltapH). The reason for the difference seen in the behaviour of the components of the protonmotive force was investigated but not established. 4. In the presence of oligomycin and ADP, oxidation of pyruvate, but not of glycerol 3-phosphate, supported a greater protonmotive force than in State 4, in keeping with the dehydrogenase activation and increased redox span NAD-cytochrome c found under these conditions. 5. Experiments involving the use of uncoupling agent to stimulate respiration are compared with those in which limiting concentrations of ADP were used. Estimates of the proton conductance of the inner membrane indicate a similar non-linear dependence on uncoupler concentration with the two substrates. 6. A model is proposed as an explanation of the high rates of controlled glycerol 3-phosphate oxidation. The model relies on a high permeability of the inner membrane to protons and other ions being induced by glycerol 3-phosphate oxidation in State 4.     

Feeding biology of sunfishes: patterns of variation in the feeding mechanism

Fishes are generally believed to differ in their ability to alter (modulate) their feeding behaviour in response to different prey. We investigated modulation quantitatively in four species of sunfishes (Centrarchidae) by evaluating the variation in 11 electromyographic variables measured from recordings of electrical activity in head muscles during feeding on three prey types. The experimental design used allowed us to partition variation between species, among individuals within species, among prey types, and among feedings. Duration of activity of the sternohyoideus muscle was the only variable significantly different among the four species. All variables showed significant differences among individuals within species. The overall range of activity of each muscle activity variable was about the same for all four sunfishes. However, three species showed a significant ability to modulate most muscle variables while a fourth did not change its feeding response with respect to prey type. The results indicate that: (1) intraspecific variation is an important source of variability in functional attributes that should be accounted for in comparisons between species; (2) the ability of some species to modulate appears to be independent of the potential variability in muscle activity possessed by each species; (3) closely related species can differ considerably in their ability to alter muscle electrical activity patterns during feeding; and (4) a quantitative assessment of variation in electromyographic patterns is a powerful approach for asking questions about differences in feeding behaviour.     

The influence of relative plant density and floral morphological complexity on the behaviour of bumblebees

We assessed the combined effects of varying the relative density and the relative floral morphological complexity of plant species on the behaviour of their bumblebee pollinators. Three species of bumblebee (Bombus pascuorum, B. terrestris and B. hortorum) were observed foraging on experimental arrays consisting of pair-wise combinations of four plant species: Borago officinalis, Phacelia tanacetifolia (both with simple flowers), Antirrhinum majus and Linaria vulgaris (both with complex flowers). Plant arrangements consisted of either two simple-flower species, a simple with a complex species or two complex species. The number of plants in each array was constant, while the frequency of each species was manipulated so that it was either rare, equal or common compared with its competitor. Contrary to predictions, rare plants were actually at an advantage in terms of the number of bees attracted per plant. However, rare plants were at a disadvantage in terms of pollen wastage because foragers more often went to a flower of another species after visiting a rare plant. The behaviour of bees on each plant species was further affected by plant floral complexity and the identity of the other species in the array. The three bumblebee species were markedly different in their foraging behaviour and in their responses to varying floral density and complexity. Each species preferred particular flower species. The results are discussed with reference to resource partitioning among bumblebee species. Received: 29 July 1998 / Accepted: 5 October 1998     

Kinetic modeling and exploratory numerical simulation of chloroplastic starch degradation

Background

The chemotaxis pathway in the bacterium Escherichia coli allows cells to detect changes in external ligand concentration (e.g. nutrients). The pathway regulates the flagellated rotary motors and hence the cells' swimming behaviour, steering them towards more favourable environments. While the molecular components are well characterised, the motor behaviour measured by tethered cell experiments has been difficult to interpret.

Results

We study the effects of sensing and signalling noise on the motor behaviour. Specifically, we consider fluctuations stemming from ligand concentration, receptor switching between their signalling states, adaptation, modification of proteins by phosphorylation, and motor switching between its two rotational states. We develop a model which includes all signalling steps in the pathway, and discuss a simplified version, which captures the essential features of the full model. We find that the noise characteristics of the motor contain signatures from all these processes, albeit with varying magnitudes.

Conclusions

Our analysis allows us to address how cell-to-cell variation affects motor behaviour and the question of optimal pathway design. A similar comprehensive analysis can be applied to other two-component signalling pathways.     

Gymnotus capanema, a new species of electric knife fish (Gymnotiformes, Gymnotidae) from eastern Amazonia, with comments on an unusual karyotype

Gymnotus capanema n. sp. is described on the basis of cytogenetic, morphometric, meristic and osteological data from nine specimens (one male and eight females) from the municipality of Capanema, Pará, in the eastern Amazon of Brazil. Later, three additional specimens were found in museums and regarded as nontypes (not cytogenetically analysed). Gymnotus capanema, which occurs in sympatry with Gymnotus cf. carapo cytotype 2n = 42 (30m/sm + 12st/a) exhibits a novel karyotype for the genus, with 2n = 34 (20m/sm + 14st/a). Gymnotus capanema can be unambiguously diagnosed from all congeners on the basis of a combination of characters from external anatomy, pigmentation and osteology. The constitutive heterochromatin, rich in adenine-thymine (A-T) base pairs [4',6 diamidino-2-phenylindole dihydrochloride (DAPI) positive], occurs in the centromeric region of all of the chromosomes, and in the pericentromeric and the entire short arm of some chromosomes. The nucleolar organizing region (NOR), stained by silver nitrate, chromomycin A(3) (CMA(3)) and 18S ribosomal (r)DNA fluorescence in situ hybridization (FISH), occurs in the short arm of pair 15. FISH, with telomeric probes did not show interstitial telomeric sequences (ITS), despite the reduced 2n in comparison to the karyotypes of other species of Gymnotus. The karyotype of G. capanema, with a reduced 2n, is strikingly different from all other previously studied congeners.     

Behavioural evolution and domestic degeneration in obligatory slave-making ants (Hymenoptera: Formicidae: Leptothoracini)

The foraging and nest emigration abilities of the obligatory slave-making ants, Harpagoxenus canadensis, H. sublaevis and H. americanus, were examined in laboratory experiments involving both natural and slave-deprived colonies. The slave-makers contributed relatively little to these domestic tasks when slaves were present, but their apparent abilities expanded to varying degrees in the absence of slaves. H. canadensis appeared to be the most self-sufficient of the three species and displayed a surprisingly full repertoire of foraging and emigration behaviour, including the ability to recruit nestmates by ‘tandem running’ in both contexts. The relative degree of domestic degeneration in these species was correlated with the extent of their behavioural specialization for conducting slave-raids. These results reinforce current views regarding the evolution of slavery among leptothoracine ants.