Walter Heiligenberg: the jamming avoidance response and beyond

Walter Heiligenberg (1938–1994) was an exceptionally gifted behavioral physiologist who made enormous contributions to the analysis of behavior and to our understanding of how the brain initiates and controls species-typical behavioral patterns. He was distinguished by his rigorous analytical approach used in both behavioral studies and neuroethological investigations. Among his most significant contributions to neuroethology are a detailed analysis of the computational rules governing the jamming avoidance response in weakly electric fish and the elucidation of the principal neural pathway involved in neural control of this behavior. Based on his work, the jamming avoidance response is perhaps the best-understood vertebrate behavior pattern in terms of the underlying neural substrate. In addition to this pioneering work, Heiligenberg stimulated research in a significant number of other areas of ethology and neuroethology, including: the quantitative assessment of aggressivity in cichlid fish; the ethological analysis of the stimulus–response relationship in the chirping behavior of crickets; the exploration of the neural and endocrine basis of communicatory behavior in weakly electric fish; the study of cellular mechanisms of neuronal plasticity in the adult fish brain; and the phylogenetic analysis of electric fishes using a combination of morphology, electrophysiology, and mitochondrial sequence data.T. H. Bullock: deceased 2005     

Scanning electron microscopy of photoreceptor cells in the light- and dark-adapted retina of Haplochromis burtoni (Cichlidae,Teleostei)

Summary The photoreceptor layer in the retina of Haplochromis burtoni (Cichlidae, Teleostei) was studied by scanning electron microscopy. Three types of receptors were identified: rods, single-cones and double-cones. The three-dimensional arrangement of these photoreceptors is described in the light- and dark-adapted retina. The surface of the inner segment of the photoreceptor cells displays fine vertical fissures which give rise to slender processes. These so called calycal processes which are of different lengths in rods and cones, surround the beginning of the smooth-surfaced outer segment. The myoid, the contractile part of the receptor, which is located beneath the ellipsoid, was examined in the single-cones of the dark-adapted retina. It is a slender structure with surface infoldings. The myoid, studied by transmission electron microscopy, contains bundles of parallel myofilaments, which are thought to be contractile.This investigation was supported by grants of the Deutsche Forschungsgemeinschaft (Sonderforschungsbereich 51-E/10)     

Opposing interactions between homothorax and Lobe define the ventral eye margin of Drosophila eye

Patterning in multi-cellular organisms involves progressive restriction of cell fates by generation of boundaries to divide an organ primordium into smaller fields. We have employed the Drosophila eye model to understand the genetic circuitry responsible for defining the boundary between the eye and the head cuticle on the ventral margin. The default state of the early eye is ventral and depends on the function of Lobe (L) and the Notch ligand Serrate (Ser). We identified homothorax (hth) as a strong enhancer of the L mutant phenotype of loss of ventral eye. Hth is a MEIS class gene with a highly conserved Meis-Hth (MH) domain and a homeodomain (HD). Hth is known to bind Extradenticle (Exd) via its MH domain for its nuclear translocation. Loss-of-function of hth, a negative regulator of eye, results in ectopic ventral eye enlargements. This phenotype is complementary to the L mutant phenotype of loss-of-ventral eye. However, if L and hth interact during ventral eye development remains unknown. Here we show that (i) L acts antagonistically to hth, (ii) Hth is upregulated in the L mutant background, and (iii) MH domain of Hth is required for its genetic interaction with L, while its homeodomain is not, (iv) in L mutant background ventral eye suppression function of Hth involves novel MH domain-dependent factor(s), and (v) nuclear localization of Exd is not sufficient to mediate the Hth function in the L mutant background. Further, Exd is not a critical rate-limiting factor for the Hth function. Thus, optimum levels of L and Hth are required to define the boundary between the developing eye and head cuticle on the ventral margin.     

Optic tract cells projecting to the retina in the teleost,Pantodon buchholzi

Summary Horseradish peroxidase was employed to trace retino-fugal and retino-petal connections in the teleost fish, Pantodon buchholzi. Most of the reciprocal connections found were within the range also observed in previously studied species of teleosts. Of particular interest is the discovery of cells located within the optic tract and projecting to the retina. These neurons were investigated electron microscopically.     

Retinofugal and retinopetal projections in the teleost Channa micropeltes (Channiformes)

Summary Retinofugal and retinopetal projections were investigated in the teleost fish Channa micropeltes (Channiformes) by means of the cobaltous lysine and horseradish peroxidase (HRP) tracing techniques. Retinofugal fibers cross completely in the optic chiasma. A conspicious lamination is present in those parts of the optic tract that give rise to the marginal branches of the optic tract. This layering of optic fibers continues in the marginal branches to mesencephalic levels. Retinal projections to the preoptic and hypothalamic regions are sparse; they are more pronounced in the area of pretectal nuclei. The medial pretectal complex and the cortical pretectal nucleus are more fully differentiated than in other teleostean species. Further targets include the thalamus and the optic tectum. The course of major optic sub-tracts and smaller fascicles is described. Retinopetal neurons are located contralaterally in a rostral and a caudal part of the nucleus olfactoretinalis, and in a circumscribed nucleus thalamoretinalis. The present findings are compared with reports on other teleost species.     

Anterograde labelling from the optic nerve reveals multiple central targets in the teleost,Lethrinus chrysostomus (Perciformes)

Summary Cobaltous-lysine is transported anterogradely from the optic nerve of the teleost, Lethrinus chrysostomus (Lethrinidae, Perciformes). The marginal optic tract is labelled in longtitudinal bands of light and dark staining fibres which persists caudally within the ventral division but not in the dorsal division. This species possesses multiple central targets in the contralateral preoptic, diencephalic, pretectal, periventricular and tectal regions of the brain. In addition, a greater subdivision of the marginal optic tract is found to project to various nuclei. Ipsilateral projections are found in the suprachiasmatic nucleus and in the region of the horizontal commissure. Projections are also found in the telencephalic region of the nucleus olfactoretinalis and the thalamic region of the nucleus thalamoretinalis. The retinotopicity of some of these nuclei, found in previous studies, is discussed in relation to the possibility of specific sub-populations of retinal ganglion cells having different central targets.Abbreviations used in the Text and Figures A nucleus anteriorthalami - AO accessory optic nucleus - AOT accessory optic tract - AxOT axial optic tract - BO nucleus of the basal optic root - C cerebellum - HCv ventral division of horizontal commissure - I nucleus intermedius thalami - IL inferior lobe - MdOT medial optic tract - MO medulla oblongata - MOTd dorsal division of the marginal optic tract - MOTi intermediate division of the marginal optic tract - MOtv ventral division of the marginal optic tract - O olfactory bulb - OT optic tract - PC nucleus pretectalis centralis - PCo posterior commissure - Pd nucleus pretectalis dorsalis - PG preglomerular complex - PPd nucleus pretectalis periventricularis, pars dorsalis - PPv nucleus pretectalis periventricularis, pars ventralis - PSm nucleus pretectalis superficial pars magnocellularis - PSp nucleus pretectalis superficialis, pars parvocellularis - Sn suprachiasmatic nucleus - TEL telencephalon - TeO optic tectum - TL torus longtitudinalis - TrOlfR tractus olfactoretinalis - VCg granular layer of the valvula cerebelli - VCm molecular layer of the valvula cerebelli - VM nucleus medialis thalami - VL nucleus ventrolateralis thalami - VMdOT ventro-medial optic tract     

Adaptation of intestinal cell membrane enzymes to low temperatures in the Antarctic teleost Pagothenia bernacchii

The enzymatic activity (expressed as milliunits per milligram total proteins) of three intestinal brush-border membrane enzymes, leucine aminopeptidase, alkaline phosphatase and maltase, measured over a range of temperatures between 1.5 and 37 °C, has been found to be much higher in the Antarctic fish Pagothenia bernacchii than in the temperate fish Anguilla anguilla. To explain this experimental observation the apparent Michaelis-Menten constant, the maximal velocity, the activation energy values and the thermal stability of these three enzymes were measured. The apparent Michaelis-Menten constant values of leucine amino peptidase and alkaline phosphatase were different in the intestine mucosal homogenate of the two fish at each measured temperature (from a minimum of 2.5 to a maximum of 37 °C). However, the values found at 2.5 °C for the Antarctic species and 15 °C for the eel where comparable. Furthermore, its value was unchanged in eel intestine apical membranes, both in the presence and without enzyme lipid microenvironment. While the maximal enzymatic activities of the leucine aminopeptidase and maltase did not decrease without their enzyme lipid microenvironment, produced by treatment with Triton X-100, the impairment of alkaline phosphatase maximal activity cannot be significantly differentiated from a non-specific inhibitory effect of the detergent. The activation energy values of leucine amino peptidase, alkaline phosphatase and maltase were lower in the Antarctic fish (11.7, 5.6 and 11.8 kcal·mol^-1, respectively) than in the eel (13.6, 7.6 and 13.1 kcal·mol^-1, respectively). The thermal stability of alkaline phosphatase and maltase is different in Pagothenia bernacchii and Anguilla anguilla intestinal homogenate.Abbreviations BBM brush border membrane - E _a activation energy - EGTA ethyleneglycol-bis-(-amino ethylether)N, N-tetraacetic acid - HEPES 2-[4-(2-hydroxyethyl)-1-piperazinyl]-ethane sulphonic acid - Km_app apparent Michaelis-Menten constant - PMSF phenylmethyl-sulphonyl fluoride - TRIS TRIS (hydroxymethyl)-aminomethane     

Hydrogen peroxide-induced chlorophyll a bleaching in the cytochrome b 6 f complex: a simple and effective assay for stability of the complex in detergent solutions

The instability of cytochrome b ₆ f complex in detergent solutions is a well-known problem that has been studied extensively, but without finding a satisfactory solution. One of the important reasons can be short of the useful method to verify whether the complex suspended in different detergent is in an intact state or not. In this article, a simple and effective assay for stability of the complex was proposed based on the investigation on the different effects of the two detergents, n-octyl-β-d-glucopyranoside (OG) and dodecyl-β-d-maltoside (DDM), on the properties of the complex. DDM stabilizes the complex preparation more effectively whereas OG denatures the interactions of the heme groups and pigment molecules with the protein environment, leading to the bleaching of chlorophyll a induced by addition of hydrogen peroxide. The assay of the use of hydrogen peroxide to characterize the complex by studying the bleaching of chlorophyll induced by hydrogen peroxide and the peroxidase activity of the complex was discussed. This simple method will probably be useful to study the stability of the complex. Xiao-Bo Chen and Xiao-Hui Zhao contributed equally to this work.     

Occasional egg-eating by the scale-eater Plecodus straeleni (Cichlidae) of Lake Tanganyika

Synopsis Of 23 males and 39 females of Plecodus straeleni observed for one hour each, 2 males and 14 females searched for the mouthbrooder Cyathopharynx furcifer under courtship display near or in the bower to get eggs, besides foraging for other prey to ripe off scales and skin. After finding a courting C. furcifer, they quietly waited on the substrate near the bower until it spawned. Immediately after spawning, the waiting P. straeleni dashed upon the female of C. furcifer and quickly collected the eggs. This egg-eating was achieved 5 times by 3 females who spent most of their time searching and waiting.     

Development of neural lineages derived from the sine oculis positive eye field of Drosophila

The Anlage of the Drosophila visual system, called eye field, comprises a domain in the dorso-medial neurectoderm of the embryonic head and is defined by the expression of the early eye gene sine oculis (so). Beside the eye and optic lobe, the eye field gives rise to several neuroblasts that contribute their lineages to the central brain. Since so expression is only very short lived, the later development of these neuroblasts has so far been elusive. Using the P-element replacement technique [Genetics, 151 (1999) 1093] we generated a so-Gal4 line driving the reporter gene LacZ that perdures in the eye field derived cells throughout embryogenesis and into the larval period. This allowed us to reconstruct the morphogenetic movements of the eye field derived lineages, as well as the projection pattern of their neurons. The eye field produces a dorsal (Pc1/2) and a ventral (Pp3) group of three to four neuroblasts each. In addition, the target neurons of the larval eye, the optic lobe pioneers (OLPs) are derived from the eye field. The embryonically born (primary) neurons of the Pp3 lineages spread out at the inner surface of the optic lobe. Together with the OLPs, their axons project to the dorsal neuropile of the protocerebrum. Pp3 neuroblasts reassume expression of so-Gal4 in the larval period and produce secondary neurons whose axonal projection coincides with the pattern formed by the primary Pp3 neurons. Several other small clusters of neurons that originate from outside the eye field, but have axonal connections to the dorsal protocerebrum, also express so and are labeled by so-Gal4 driven LacZ. We discuss the dynamic pattern of the so-positive lineages as a tool to reconstruct the morphogenesis of the larval brain.     

Mhc class I genes of the cichlid fish Oreochromis niloticus

In terms of number of species, perciform (perch-like) fishes are one of the most diversified groups of modern vertebrates. Within this group, the family Cichlidae is best known for its spectacular adaptive radiation in the great lakes of East Africa. The molecular tool kit used in the study of this radiation includes the major histocompatibility complex (Mhc) genes. To refine this tool, information about the organization of the Mhc regions is badly needed. In this study, the first step was taken toward providing such information for the Mhc class one regions of Oreochromis niloticus, a representative species of the tilapiine branch of the Cichlidae, for which good bacterial artificial chromosome library is available. Screening of the library with class I gene probes led to the identification and isolation of 31 class-I-positive clones. Sequencing of one of these clones and partial characterization of the remaining clones for the presence of class I exons resulted in the construction of two contigs representing the class I region of this species as well as identification of seven additional class-I-positive singleton clones. The O. niloticus genome was shown to contain at least 28 class I genes or gene fragments. The shorter of the two contigs was approximately 330 kb long and contained eight class I genes/gene fragments; the longer contig encompassed 1,200 kb of sequence and contained minimally 17 class I genes/gene fragments; three additional class I genes were found to be borne by a clone that might be part of the shorter contig. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. This work had been carried out in part at the Max-Planck-Institut für Biologie, Abteilung Immungenetik, Tübingen, Germany (A.S., R.D., N.T., S.S., and J.K.). The sequences reported in this paper have been deposited in the GenBank database (accession nos. AB270803–AB270897).     

High toxicity of the novel bloom-forming species Chattonella ovata (Raphidophyceae) to cultured fish

A toxicological study of an axenic cell line of novel species Chattonella ovata Y. Hara et Chihara (Raphidophyceae) revealed that cultured species of sea bream (Pagrus major), horse mackerel (Trachurus japonicus), and yellowtail (Seriola quinqueradiata) were killed by 4.1–6.8 × 10³, 5.4 × 10³, and 2.8 × 10³ cells/mL, respectively. The sensitivity of the gill lamellae to C. ovata differed among the fish species tested. This finding revealed that C. ovata was highly toxic to the cultured fish. Histological examination showed that edema and hyperplasia of the secondary gill lamellae of red sea bream and horse mackerel occurred when exposed to, or killed by C. ovata, whereas severe damage in the gill lamellae was not observed in yellowtail. Chattonella produced high amounts of superoxide anion radicals and hydrogen peroxide, possibly responsible for the fish death observed. Based on the results of this study and occurrence of a red tide by this organism in China in 2001, we consider this organism to be one of the harmful algae in coastal waters. This is the first report demonstrating that C. ovata is highly toxic to fish, and that it produces superoxide and hydrogen peroxide.     

The novel light-harvesting pigment-protein complex ofMantoniella squamata (Chlorophyta): Phylogenetic implications

Summary A light-harvesting pigment-protein complex has been isolated fromMantoniella squamata (Micromonadophyceae, Chlorophyta) by nondenaturing polyacrylamide-gel electrophoresis. The complex runs as two bands of molecular weights 54,000 and 55,000. There are two constituent polypeptides of molecular weights 20,500 and 22,000. Antibodies were raised to the 20,500-dalton polypeptides from this complex and to the 24,500-dalton polypeptide from the analogous complex ofPedinomonas minor (Micromonadophyceae). The antibodies to theM. squamata polypeptide are specific for both polypeptides of theM. squamata light-harvesting complex, as well as for a 27,000-dalton polypeptide of undetermined function. The antibodies to theP. minor polypeptide are specific for polypeptide components of the light-harvesting complex of that alga. The antibodies specific for theM. squamata light-harvesting complex polypeptides do not cross react with any polypeptides ofP. minor thylakoid membranes, as demonstrated by crossed immunoelectrophoresis. Similarly, no polypeptides ofM. squamata thylakoids cross react with the antibodies specific forP. minor light-harvesting complex polypeptides. These results indicate that the light-harvesting complex ofM. squamata is structurally very different from that ofP. minor. In a survey of several land plants and green algae, including representatives of all classes of green algae, a light-harvesting complex homologous to that ofM. squamata was found only inMicromonas pusilla. All other organisms tested possessed a lightharvesting complex homologous to that ofP. minor. The evolutionary and taxonomic implications of the novelM. squamata light-harvesting complex are discussed.     

Properties of histamine-activated chloride channels in the large monopolar cells of the dipteran compound eye: a comparative study

The large monopolar cells (LMCs) of the first optic neuropil (lamina) in insects respond to the photoreceptor neurotransmitter histamine with an increase in chloride conductance. We have compared the properties of this conductance from a range of diptera from different visual environments: Tipula paludosa (slow flying, crepuscular), Drosophila melanogaster (slow-flying diurnal), and 3 fast-flying diurnal species Musca domestica, Calliphora vicina and Lucilia sericata. In whole-cell recordings of dissociated LMCs, histamine-induced currents were elicited using a multichannel parallel perfusion device, allowing rapid determination of the dose-response function, characterised by affinity (K _d) and Hill coefficient (n). Calliphora, Lucilia and Musca had the steepest dose response curves (n = 2.8) and the lowest affinity for histamine (K _d 35–50 M); the crepuscular Tipula had a significantly higher affinity (K _d = 16 M) and lower Hill coefficient (n = 1.8). Drosophila had a high affinity (K _d 24 M), and a high Hill coefficient (n = 2.5). In excised inside-out patch recordings all species showed similar single channel properties (conductance 40–60 pS, mean open time < 1 ms). The low Hill coefficient in Tipula would be expected to result in lower synaptic gain. We suggest this may be an adaptation to prevent the LMC's response bandwidth being filled with the high levels of photon noise typical of photoreceptors adapted for low light levels. The lower affinity for histamine found in the more photopic species suggests that the concentration of histamine (and therefore presumably number of synaptic vesicles released from the photoreceptors) should be higher. This might improve signal-to-noise ratio by decreasing the contribution of the shot event noise introduced by stochastic release of synaptic vesicles.Abbreviations LMC large monopolar cell - TES N Tris-(hydroxymethyl)-methyl-2-amino-ethane-sulphonic acid - K _D slow delayed rectifier - K _A transient A current - K _a apparent dissociation constant     

Growth and maturation of melanosomes in the melanophores of a teleost,Oryzias latipes

Summary Formation of melanosomes in melanophores of a teleost, Oryzias latipes, was studied by means of electron microscopy. Two distinct types of premelanosomes are observed in the same cell: (i) multivesicular premelanosomes, which later develop into melanosomes with electron-lucent hollows in the center, appear at early embryonic stages; (ii) premelanosomes with highly organized, fibrous internal structure are formed at later stages of development and give rise to melanosomes with a filamentous center. Melanosomes are generally ellipsoid in shape, and the difference in the dimensions of fibrillar premelanosomes, melanosomes in the cells at younger developmental stages and those developed fully in melanophores of adults indicates that these organelles grow during development. The growth is achieved by fusion of small unmelanized vesicles or fibrillar premelanosomes to preformed melanosome and by fusion of two or more premelanosomes to form a larger organelle. The addition of the matrix of fibrillar premelanosomes around preformed melanosomes, which are derived from either multivesicular or fibrillar premelanosomes, forms a concentric outer deposit, and the fusion of small vesicles produces electron-lucent pits which are scattered irregularly in mature melanosomes.     

A novel eye morphology induced by a P element in somatic tissue of Drosophila melanogaster.

Summary We found a specific eye morphology designated as Square, which is induced when some Drosophila melanogaster strains harboring P elements are crossed with the 2–3 strain carrying a modified P element, P[ry ⁺, 2–3], which produces transposase in somatic tissue. This phenotype was dominant and also induced in the reciprocal crosses. Square was induced when the 2–3 strain was crossed with Q and M strains such as the sn^w (M) strain carrying three small P elements but not with P strains. Inheritance of Square was also tested and its phenotype was not transmitted to the next generation. These results suggest that Square is caused by the transposition of P elements in somatic cells.     

Evoked pre- and post-synaptic activity in the optic tectum of the cannulated tadpole

Summary We describe the cannulated Rana pipiens, tadpole preparation that allows for stable recording in the tectum of the extracellular potential elicited by optic nerve stimulation. The largest components of the evoked tectal response consist of two previously identified waves and a major third, long-latency wave of long duration. These components were reversibly eleminated by perfusion of high magnesium/no calcium Ringer's solution or Ringer's solution containing cobalt chloride. In contrast, perfusion of high calcium/no magnesium Ringer's increased the amplitude and area of these components. We conclude that these components represent post-synaptic activity.Additionally, small, short-duration waves were identified as arising from the activity of retinal afferents. They consisted of a short-latency (3.1–7.6 ms) and a long-latency (12–23 ms) group. Waves belonging to both of these classes were still visible in both high magnesium/ no calcium Ringer's solution or Ringer's solution containing cobalt chloride and were unaffected by high calcium/no magnesium Ringer's. The average conduction velocities of the short- and long-latency groups matched the conduction velocities of, respectively, edge and convexity detectors in the adult. This indicates that retinal afferent input may already be present in adult patterns at the time that tectal circuitry is developing.Abbreviations TTX tetrodotoxin - NMDA N-methyl-D-aspartate - APV 2-amino-5-phosphonovaleric acid     

Immunohistochemical study of 5-HT-containing neurons in the teleost intestine: relationship to the presence of enterochromaffin cells

Summary The formaldehyde-induced fluorescence technique had shown 5-hydroxytryptamine-containing enteric neurons in the intestine of the teleost Platycephalus bassensis, but did not reveal such neurons in the intestine of Tetractenos glaber or Anguilla australis. Re-examination of these animals with 5-hydroxytryptamine immunohistochemistry showed immunoreactive enteric neurons in the intestine of all three teleost species. The 5-hydroxytryptamine-containing enteric neurons showed essentially the same morphology in all species examined: the somata were situated in the myenteric plexus, extending down into the circular muscle layer, but none were found in the submucosa; processes were found in the myenteric plexus, the circular muscle layer and the lamina propria. It was concluded that the neurons may innervate the muscle layers or the mucosal epithelium, but were unlikely to be interneurons. In a range of teleosts, enterochromaffin cells were found in the intestine of only those species in which the formaldehyde technique did not visualize neuronal 5-hydroxytryptamine. Available evidence suggests that, in vertebrates, 5-HT-containing enterochromaffin cells are lacking only where there is an innervation of the gut mucosa by nerve fibres containing high concentrations of 5-HT.