Biorefinery potential of sustainable municipal wastewater treatment using fast-growing willow.

The use of willow plantations can be a sustainable approach for treating primary municipal wastewater, potentially reducing both the environmental and economic burdens associated with conventional treatment. However, the impact of wastewater irrigation upon the willow biorefinery potential has not yet been established. To investigate this effect, three-year-old field grown willows were harvested from plots kept as either controls or irrigated with primary municipal wastewater effluent at 29.5 million L ha-1 yr-1. Biomass compositional analysis, ionic liquid pretreatment and enzymatic saccharification were assessed and differential abundance of persistent extractable phytochemicals was evaluated using untargeted metabolite profiling. Glucan significantly increased by 8% in wastewater treated trees, arabinose and galactose were significantly decreased by 8 and 29%, respectively, while xylose, mannose and lignin content were unaltered. Ionic liquid pretreatment and enzymatic saccharification efficiencies did not vary significantly, releasing >95% of the cell wall glucose and recovering 35% of the lignin. From a total of 213 phytochemical features, 83 were significantly depleted and 14 were significantly enriched due to wastewater irrigation, including flavonoids and lignan derivatives. Considered alongside increased biomass yield from wastewater irrigation (+200%), lignocellulosic bioenergy yields increased to 8.87 t glucose ha-1 yr-1 and 1.89 t ha-1 yr-1 recovered lignin, while net extractives yields increased to 1.48 t ha-1 yr-1, including phytochemicals of interest. The maintenance of glucose accessibility after low-cost ionic liquid pretreatment is promising evidence that sustainable lignocellulose bioenergy production can complement wastewater treatment. Untargeted metabolite assessment revealed some of the phytochemical toolkit employed by wastewater irrigated willows, including accumulation of flooding and salinity tolerance associated flavonoids glabraoside A and glabrene. The extractable phytochemicals underpin a novel high biomass phenotype in willow and, alongside lignocellulosic yields, could help enhance the economic feasibility of this clean wastewater treatment biotechnology through integration with sustainable biorefinery.

High biomass yield increases in a primary effluent wastewater phytofiltration are associated to altered leaf morphology and stomatal size in Salix miyabeana.

Municipal wastewater treatment using willow 'phyto'-filtration has the potential for reduced environmental impact compared to conventional treatment practices. However, the physiological adaptations underpinning tolerance to high wastewater irrigation in willow are unknown. A one-hectare phytofiltration plantation established using the Salix miyabeana cultivar 'SX67' in Saint-Roch-de-l'Achigan, Quebec, Canada, tested the impact of unirrigated, potable water or two loads of primary effluent wastewater 19 and 30 ML ha-1 yr-1. A nitrogen load of 817 kg N ha-1 from wastewater did not increase soil pore water nitrogen concentrations beyond Quebec drinking water standards. The willow phytofiltration phenotype had increased leaf area (+106-142%) and leaf nitrogen (+94%) which were accompanied by significant increases in chlorophyll a + b content. Wastewater irrigated trees had higher stomatal sizes and a higher stomatal pore index, despite lower stomatal density, resulting in increased stomatal conductance (+42-78%). These developmental responses led to substantial increases in biomass yields of 56-207% and potable water controls revealed the nitrogen load to be necessary for the high productivity of 28-40 t ha-1 yr-1 in wastewater irrigated trees. Collectively, this study suggests phytofiltration plantations could treat primary effluent municipal wastewater at volumes of at least 19 million litres per hectare and benefit from increased yields of sustainable biomass over a two-year coppice cycle. Added-value cultivation practices, such as phytofiltration, have the potential to mitigate negative local and global environmental impact of wastewater treatment while providing valuable services and sustainable bioproducts.

Synthesis and spectroscopic characterization on 4-(2,5-di-2-thienyl-1H-pyrrol-1-yl) benzoic acid: A DFT approach.

A complete structural and vibrational analysis of the 4-(2,5-di-2-thienyl-1H-pyrrol-1-yl) benzoic acid (TPBA), was carried out by ab initio calculations, at the density functional theory (DFT) method. Molecular geometry, vibrational wavenumbers and gauge including atomic orbital (GIAO) (13)C NMR and (1)H NMR chemical shift values of (TPBA), in the ground state have been calculated by using ab initio density functional theory (DFT/B3LYP) method with 6-311G(d,p) as basis set for the first time. Comparison of the observed fundamental vibrational modes of (TPBA) and calculated results by DFT/B3LYP method indicates that B3LYP level of theory giving yield good results for quantum chemical studies. Vibrational wavenumbers obtained by the DFT/B3LYP method are in good agreement with the experimental data. The study was complemented with a natural bond orbital (NBO) analysis, to evaluate the significance of hyperconjugative interactions and electrostatic effects on such molecular structure. By using TD-DFT method, electronic absorption spectra of the title compound have been predicted and a good agreement with the TD-DFT method and the experimental one is determined. In addition, the molecular electrostatic potential (MEP), frontier molecular orbitals analysis and thermodynamic properties of TPBA were investigated using theoretical calculations.

DFT calculations and experimental FT-IR, FT-Raman, NMR, UV-Vis spectral studies of 3-fluorophenylboronic acid.

The spectroscopic (FT-IR, FT-Raman, (1)H and (13)C NMR, UV-Vis), structural, electronic and thermodynamical properties of 3-fluorophenylboronic acid (C6H4FB(OH)2), 3FPBA) were submitted by using both experimental techniques and theoretical methods (quantum chemical calculations) in this work. The experimental infrared and Raman spectra were obtained in the region 4000-400 cm(-1) and 3500-10 cm(-1), respectively. The equilibrium geometry and vibrational spectra were calculated by using DFT (B3LYP) with 6-311++G(d,p) basis set. The vibrational wavenumbers were also corrected with scale factor to take better results for the calculated data. The total energy distributions (TED) of the vibrational modes were performed for the assignments of the title molecule by using scaled quantum mechanics (SQM) method. The NMR chemical shifts ((1)H and (13)C) were recorded in DMSO solution. The (1)H and (13)C NMR spectra were computed by using the gauge-invariant atomic orbital (GIAO) method, showing a good agreement with the experimental ones. The last one UV-Vis absorption spectra were analyzed in two solvents (ethanol and water), saved in the range of 200-400 nm. In addition these, HOMO and LUMO energies, the excitation energies, density of states (DOS) diagrams, thermodynamical properties and molecular electrostatic potential surface (MEPs) were presented. Nonlinear optical (NLO) properties and thermodynamic features were performed. The experimental results are combined with the theoretical calculations using DFT calculations to fortification of the paper. At the end of this work, the results were proved our paper had been indispensable for the literature backing.

FT-IR, FT-Raman, NMR and UV-Vis spectra and DFT calculations of 5-bromo-2-ethoxyphenylboronic acid (monomer and dimer structures).

In this study, the Fourier Transform Infrared (FT-IR) and Fourier Transform Raman (FT-Raman) spectra of 5-bromo-2-ethoxyphenylboronic acid (5Br2EPBA) are recorded in the solid phase in the region 4000-400 cm(-1) and 3500-10 cm(-1), respectively. The (1)H, (13)C and DEPT nuclear magnetic resonance (NMR) spectra are recorded in DMSO solution. The UV-Vis absorption spectrum of 5Br2EPBA is saved in the range of 200-400 nm in ethanol and water. The following theoretical calculations for monomeric and dimeric structures are supported by experimental results. The molecular geometry and vibrational frequencies in the ground state are calculated by using DFT methods with 6-31G(d,p) and 6-311G(d,p) basis sets. There are four conformers for the present molecule. The computational results diagnose the most stable conformer of 5Br2EPBA as Trans-Cis (TC) form. The complete assignments are performed on the basis of the total energy distribution (TED) of vibrational modes, calculated with scaled quantum mechanics (SQM) method in parallel quantum solutions (PQS) program. The (1)H and (13)C NMR chemical shifts of 5Br2EPBA molecule are calculated by using the Gauge Invariant Atomic Orbital (GIAO) method in DMSO and gas phase for monomer and dimer structures of the most stable conformer. Moreover, electronic properties, such as the HOMO and LUMO energies (by TD-DFT and CIS methods) and molecular electrostatic potential surface (MEPs) are investigated. Stability of the molecule arising from hyper-conjugative interactions, charge delocalization is analyzed using natural bond orbital (NBO) analysis. Nonlinear optical (NLO) properties and thermodynamic features are presented. All calculated results are compared with the experimental data of the title molecule. The correlation of theoretical and experimental results provides a detailed description of the structural and physicochemical properties of the title molecule.

Structural investigation of a self-assembled monolayer material 5-[(3-methylphenyl) (phenyl) amino] isophthalic acid for organic light-emitting devices.

The molecular structure and vibrations of 5-[(3-methylphenyl) (phenyl) amino] isophthalic acid (MePIFA) were investigated by infrared and Raman spectroscopies, UV-Vis, (1)H and (13)C NMR spectroscopic techniques and NBO analysis. FT-IR, FT-Raman and dispersive Raman spectra were recorded in the solid phase. (1)H and (13)C NMR spectra and UV-Vis spectrum were recorded in DMSO solution. HOMO-LUMO analysis and molecular electrostatic potential (MEP) analysis were performed. The theoretical calculations for the molecular structure and spectroscopies were performed with DFT (B3LYP) and 6-311G(d,p) basis set calculations using the Gaussian 09 program. After the geometry of the molecule was optimized, vibration wavenumbers and fundamental vibration wavenumbers were assigned on the basis of the potential energy distribution (PED) of the vibrational modes calculated with VEDA 4 program. The total (TDOS), partial (PDOS) density of state and overlap population density of state (OPDOS) diagrams analysis were made using GaussSum 2.2 program. The results of theoretical calculations for the spectra of the title compound were compared with the observed spectra.

[Chronic pancreatitis: microbe-intestinal tissue complex and systemic inflammatory response].

Today in Russian Federation, we observe significant growth of the chronic pancreatitis incidence with the depression of its therapy efficiency (more than 20% of the patients) and complications rate growth. In many respects given tendency is associated with the inefficiency of traditional medications combination in the context of inflammation process reduction, gut dysbiosis correction and chronic inflammation reaction depression. Present-day studies indicates, that the grade and character of inflammation in the pancreas depends on the pro- and anti-inflammatory cytokines balance, which is associated with the elevation of the pathogenic microbiota concentration and permeability of the gut. We estimate clinical efficacy of complex treatment regimen (PPI, spasmolytic, multienzyme and prebiotic therapy) in the patients with chronic pancreatitis and its effect on chronic system inflammation. We established that efficacy of modern complex treatment regimen depends on its influence on chronic system inflammation and that prebiotics addition potentiates correction of dysbiotic changes in the gut microbial-tissular complex and reduces grade of system inflammation.

Connections of the olfactory bulb in the gymnotiform fish, Apteronotus leptorhynchus.

This work examines the connectivity of the olfactory bulb in the gynmotiform fish Apteronotus leptorhynchus. Wheat germ agglutinin conjugated horseradish peroxidase was iontophoresed in different areas and depths of the bulb in order to define its efferent and afferent connections. The olfactory bulb projects bilaterally via the medial (medial and centromedial fascicles) and lateral olfactory (lateral and centrolateral fascicles) tracts. The nervus terminalis courses through the ventromedial aspect of the bulb to terminate in parts of the medial subpallium and hypothalamus. Its telencephalic component could be identified by a nonpreadsorbable substance P-like immunoreactivity. Fibers within the medial olfactory tract form four telencephalic terminal fields: peduncular, medial, intermediate and posterior fields. The diencephalic terminal fields in the habenula, preoptic, and hypothalamic areas appear to correspond to some of the nervus terminalis fibers (von Bartheld and Meyer [1986] Cell Tissue Res. 245:143-158, Krishna et al. [1992] Gen. Comp. Endocrinol. 85:111-117), and to axons of telencephalic bulbopetal cells of area dorsalis posterior. The terminal fields of the medial olfactory tract and nervus terminalis partially overlap in the ventral telencephalic areas partes ventralis, supracommissuralis, and rostral preoptic region. The lateral olfactory tract forms a lateral terminal field and contributes to the intermediate and posterior terminal fields. Olfactory fibers cross in the interbulbar, anterior, and habenular commissures and tuberal decussation. Consistent differences were noted between the medial and lateral olfactory bulb, with respect to their cytoarchitectonics, immunohistochemistry, and connections. In addition to the olfactory nerve, bulbar afferents are predominantly ipsilateral, with minor inputs originating from the contralateral bulb and telencephalic area dorsalis posterior, nucleus raphe centralis, and locus ceruleus.

Somatostatin-like immunoreactivity in the brain of an electric fish (Apteronotus leptorhynchus) identified with monoclonal antibodies.

The immunohistochemical localization of somatostatin-like immunoreactive (SSir) cells and fibers in the brain of the gymnotiform teleost (Apteronotus leptorhynchus) was investigated using well-characterized monoclonal antibodies directed against somatostatin-14 and -28. Large populations of SSir neurons occur in the basal forebrain, diencephalon and rhombencephalon and a dense distribution of fibers and terminal fields is found in the ventral, dorsomedial and dorsolateral telencephalon, hypothalamus, centralis posterior thalamus, subtrigeminal nucleus, the motor nucleus of vagus and in the ventrolateral medulla. Immunoreactive neurons in the forebrain are concentrated mainly in the ventral telencephalic areas, the region of the anterior commissure and entopeduncular nucleus. In a fashion similar to the large basal telencephalic cells of other species, the cells of the rostral nucleus entopeduncularis have a significant projection to the dorsal telencephalon. The preoptic region and the peri- and paraventricular hypothalamic nuclei are richly endowed with SSir cells; some of these cells contribute fibres to the pituitary stalk and gland. In the thalamus, only the n. centralis posterior stands out for the density of SSir cells and terminals; these cells appear to project to the prepacemaker nucleus, thus suggesting an SS influence on electrocommunication. In the mesencephalon most SSir cells occur in the optic tectum, torus semicircularis and interpeduncular nucleus. The rhombencephalic SSir cells have a wider distribution (central gray, raphe, sensory nuclei, reticular formation, electrosensory lateral line lobe and surrounding the central canal). The results of this study show the presence of SS in various sensory systems, electromotor system and specific hypothalamic nuclei, suggesting a modulatory role in the processing of sensory information, electrocommunication, endocrine and motor activities.

An atlas of the brain of the electric fish Apteronotus leptorhynchus.

This atlas consists of a set of six macrophotographs illustrating the important external landmarks of the apteronotid brain, as well as 54 transverse levels through the brain stained with cresyl violet. There are 150 microns between levels and the scales have 1 mm divisions (100 microns small divisions). In general the neuroanatomy of this brain is similar to that of other teleosts except that all parts known to be concerned with electroreception are greatly hypertrophied (electrosensory lateral line lobe, nucleus praeminentialis, caudal lobe of the cerebellum, torus semicircularis dorsalis, optic tectum and nucleus electrosensorius). There are other regions of this brain which are hypertrophied or which have not been described in other teleosts, but which are not known to be directly linked to the electrosensory/electromotor system; these regions are mentioned in the accompanying text.

Catecholaminergic systems in the brain of a gymnotiform teleost fish: an immunohistochemical study.

The localization of catecholamines (CA) in the brain of Apteronotus leptorhynchus was studied with immunohistochemical techniques using antibodies to the enzymes tyrosine hydroxylase (TH), dopamine B-hydroxylase (DBH), phenylethanolamine-N-methyltransferase (PNMT), and the neurotransmitter dopamine (DA). Telencephalic TH and DA immunoreactive (ir) neurons were located in the following structures: olfactory bulb, area ventralis telencephali partes ventralis, centralis, dorsalis, and intermediate. Diencephalic TH ir neurons were distributed in: nucleus preopticus periventricularis pars anterior, floor of preoptic recess, n. suprachiasmaticus, n. preopticus periventricularis pars posterior, n. anterior periventricularis, area ventralis lateralis, rostral region of posterior periventricular nucleus (paraventricular organ of other authors), periventricular nucleus of posterior tuberculum, n. recessus lateralis, n. tuberis lateralis pars anterior, and n. tuberis posterior. Although most diencephalic TH ir structures were also DAir, the posterior periventricular nucleus, n. recessus lateralis pars medialis, n. recessus posterioris, and ventral region of nucleus lateralis tuberis pars anterior showed differences in the distribution of TH and DA immunoreactivity. The rhombencephalic structures contained cell groups with different combinations of catecholamines as follows: TH and DBH ir neurons in the isthmic tegmentum (locus coeruleus); TH and DBH ir cells in the rostral medullary tegmentum ventral to VIIth nerve; TH and PNMT ir cells in the sensory nucleus of the vagus nerve; TH, DBH, and PNMT ir cells in the dorsal medullary tegmentum, TH and DBH ir cells in the dorsomedian postobecular region, ventral to the descending trigeminal tract and lateral to the central canal at medullospinal levels. This study shows that: (1) with few exceptions TH and DA ir coincides, (2) gymnotiforms possess similar DBH ir rhombencephalic groups, but additional telencephalic and rhombencephalic TH ir groups, and PNMT ir cells that were not reported previously in teleosts, and (3) the presence of CAergic fibers in the electrosensory system supports findings of their modulatory function in communication and aggression.

The organization of afferent input to the caudal lobe of the cerebellum of the gymnotid fish Apteronotus leptorhynchus.

The caudal lobe of the cerebellum of the high frequency gymnotid fish Apteronotus leptorhynchus is that region of the cerebellum lying lateral to the posterolateral sulcus. It consists of three granular masses--the eminentia granularis posterior pars lateralis, a transitional zone T, and the eminentia granularis posterior pars medialis--with their associated molecular layers. We have used the retrograde transport of wheat germ agglutinin conjugated horseradish peroxidase to study the afferent input to the various subdivisions of the caudal lobe. Each granular mass receives different types of input. Eminentia granularis posterior pars lateralis receives a massive bilateral input from an isthmic nucleus, nucleus praeeminentialis, concerned with descending control of the electrosensory system and from a rhombencephalic nucleus, the lateral reticular nucleus, which itself receives a major spinal input. In addition eminentia granularis posterior receives lesser input from other pretectal, (N. at base of dorsomedial optic tract, pretectal complex "B") mesencephalic (dorsal tegmental N., nucleus raphe dorsalis), isthmic (bed N. of praeeminentialis-cerebellaris tract, locus coeruleus) and rhombencephalic nuclei (lateral tegmental N., eurydendroid cells, octaval N., perihypoglossal N., paramedian reticular N., medullary reticular formation, medullary raphe, efferent octavolateralis N., inferior olive, and funicular N.). The input from nucleus praeeminentialis dorsalis is mapped topographically onto eminentia granularis posterior with respect to their rostro-caudal location. We could not define any topography in the mapping of the dorso-ventral body axis upon eminentia granularis posterior; small injections of WGA-HRP produced several small clusters of labeled cells within nucleus praeeminentialis dorsalis which does suggest a more complex organization of this projection. Zone T receives most of its input from the ipsilateral VIIIth nerve ganglion cells and certain pretectal nuclei, but it also receives a small input from nucleus praeeminentialis dorsalis. Eminentia granularis posterior pars medialis receives minor input from a small pretectal nucleus and a small ventral diencephalic nucleus, this region appears to receive its major input from eurydendroid cells of eminentia granularis posterior. The molecular layer associated with each granular mass receives contralateral input from separate clusters of inferior olivary cells. In addition the eurydendroid cells (cerebellar output neurons) of eminentia granularis posterior pars lateralis receive a substantial direct input from cells located in the medial aspect of nucleus praeeminentialis dorsalis.

The optic tectum of gymnotiform teleosts Eigenmannia virescens and Apteronotus leptorhynchus: a Golgi study.

Golgi, Nissl, Bielschowsky and cholinesterase techniques have been used to analyze the optic tectum of the weakly electric teleost fish Eigenmannia virescens and Apteronotus leptorhynchus. Six layers are readily distinguished: a fairly thick stratum marginale, a narrow stratum opticum and stratum fibrosum et griseum superficiale, a well-developed stratum griseum centrale, a stratum album centrale and a compact stratum periventriculare. Fifty-six neuronal types are present. In regard to comparative aspects of tectal organization, it became apparent that although most neuronal types are similar to those reported in other teleostean fish, there are certain obvious differences such as: pyramidal cell somata not confined to stratum fibrosum et griseum superficiale, but also clustered in the adjacent stratum opticum, presenting stratified or diffuse basilar dendritic arbors; and a change from vertical to oblique and almost horizontal neuronal orientation in the ventral and caudal tectum. The presence of pyramidal cells with aligned and misaligned apical and basal dendritic fields. A cell of stratum griseum centrale with an ascending axon to stratum opticum. A special projection type of fusiform cell of stratum griseum centrale, with an efferent axon of somatic origin. A cell rich stratum griseum centrale, with a wider variety of multipolar and bipolar cell population than reported in other teleosts. Fourteen types of pyriform cells are present, four of which are efferent. Our observations are suggestive of regional differences in regard to the caudalmost tectum in Apteronotus: presumably this is related to the extremely sparse retinal input to this part of the tectum. A close functional correlation has been found between some multipolar and pyriform cells identified in our material with similar cells reported by Rose and Heiligenberg as multisensory cells, following recordings and horseradish peroxidase fillings of these cells. Based on the observation of patchy torus semicircularis input to stratum fibrosum et griseum superficiale, disjunct from the retinal input to this layer, it is proposed that perhaps this arrangement is the result of competition for synaptic targets during development.

Retinofugal projections in a weakly electric gymnotid fish (Apteronotus leptorhynchus).

The eyes of weakly electric gymnotid fish are poorly developed in comparison to those of most diurnal teleosts. The tectum and pretectum, despite their usual association with the visual system, are large and well differentiated in gymnotids. We have studied retinal projections in gymnotids in order to define the visual components of the mesencephalon and diencephalon and thus allow comparison with other teleosts in which retinofugal fibers have been extensively mapped. Retinofugal projections reported in this work are based on the anterograde transport of conjugated wheat germ agglutinin horseradish peroxidase, following injection into the posterior chamber of the eye of Apteronotus leptorhynchus (brown ghost knife fish). The results show a remarkable similarity to those of non-electroreceptive teleosts. Although the optic nerves appear to cross completely at the optic chiasm, close scrutiny shows a slender recrossing fascicle which continues from the contralateral tractus opticus medialis through the rostroventral hypothalamus to reach the ipsilateral side, providing a scanty projection to the n. opticus hypothalamicus, n. anterior periventricularis, n. dorsolateralis thalami, and n. commissurae posterioris. A few fibers ascend via the tractus opticus dorsomedialis to the rostral dorsomedial part of the stratum fibrosum et griseum superficiale of the ipsilateral tectum. The main body of the retinal projections in Apteronotus are to the following contralateral target areas: preoptic area, n. opticus hypothalamicus, n. anterior periventricularis, n. dorsolateralis thalami, n. pretectalis, area pretectalis, n. corticalis, n. commissurae posterioris, n. geniculatus lateralis, area and n. ventrolateralis thalami, caudal dorsal tegmentum and the tectum opticum. The retinotectal projection is modest in comparison to that of more vision dependent fish and terminates mainly in the upper half of the stratum fibrosum et griseum superficiale; hardly any retinal fibers reach the caudalmost tectum.

Identification of a nucleus isthmi in the weakly electric fish Apteronotus leptorhynchus (Gymnotiformes).

The nucleus isthmi of teleost fish, amphibians, reptiles and birds, and its probable homologue, the nucleus parabigeminalis of mammals, share in common certain features such as location in the dorsal tegmentum and reciprocal connectivity with the optic tectum. In gymnotid fish the nucleus isthmi is located dorsolaterally in the brainstem tegmentum, ventral to the torus semicircularis and the lateral mesencephalic reticular area and dorsal to the rostral nucleus praeeminentialis. The nucleus isthmi has an ovoid shape, with a compact cellular part on its dorsal, medial and ventral aspects surrounding a hilar region with a sparse population of larger cells. Following wheat germ agglutinin-conjugated horseradish peroxidase injections into the optic tectum, anterogradely labeled fine terminals were observed leaving the tectobulbar tract and entering the ipsilateral nucleus isthmi via its laterally facing hilar region. Retrogradely labeled cells were present in the nucleus isthmi on both sides, indicating the presence of a bilateral isthmotectal projection similar to that reported in amphibians. The putative isthmal nucleus stains densely for acetylcholinesterase. Based on the similarity of its location, shape, cholinesterase histochemistry and reciprocal connectivity with the optic tectum, we identified this structure as the nucleus isthmi of gymnotids. An interesting observation of this study was that the nucleus isthmi, in addition to receiving fine terminals from the optic tectum, is also the recipient of a sparser population of thicker-caliber afferent fibers which terminate not only in the large-celled hilar region but also within the smaller-celled component of the nucleus; this projection appears to emanate from the torus semicircularis dorsalis.

The nucleus praeeminentialis: a Golgi study of a feedback center in the electrosensory system of gymnotid fish.

The cytoarchitecture of the dorsal nucleus praeeminentialis in two families of weakly electric fish (Eigenmannia viriscens and Apteronotus albifrons) was examined in both Nissl and Golgi material, and an attempt was made to correlate this information with our data from HRP studies on the afferent and efferent connections of this nucleus. The n. praeeminentialis is an isthmic structure located dorsolateral to the lateral lemniscus and anterior to the eminentia granularis--a subdivision of the archicerebellum of fish. The n. praeeminentialis can be divided into a large dorsal portion concerned with electroreception and a small ventral portion involved with the lateral line mechanoreception. The dorsal n. praeeminentialis consists of three parts: a pars medialis, a large pars principalis (p.P.) and a narrow pars lateralis. The p.P. presents three zones: a dorsal, a central, and a ventral zone, which are reciprocally and topographically connected with the zones of the electroreceptive lateral line lobe (ELLL), medial ELLL with ventral zone, central ELLL with central zone, and lateral ELLL with dorsal zone. Several types of projection cells are present in the n. praeeminentialis: (a) neurons that show preferential orientation of their long dendrites in relation to the afferent fiber systems, (b) cells with wide dendritic fields radiating in all directions, and (c) cells with small polarized dendritic fields toward the incoming ELLL afferents. Interneurons are also identified, showing different axonal ramification patterns. The afferent and efferent fiber systems linking the n. praeeminentialis to ELLL, lobus caudalis (L.C.), and torus semicircularis (T.S.d.) point to the important position of this nucleus in the feedback loop of the electrosensory pathway. The complex processing within this nucleus is reminiscent of the feedback loops in the auditory system.

Peripheral organization and central projections of the electrosensory nerves in gymnotiform fish.

The electrosensory system of weakly electric gymnotiform fish is described from the receptor distribution on the body surface to the termination of the primary afferents in the posterior lateral line lobe (PLLL). There are two types of electroreceptor(ampullary and tuberous) and a single type of lateral line mechanoreceptor (neuromast). Receptor counts in Apteronotus albifrons show that (1) neuromasts are distributed as in other teleosts; (2) ampullary receptors number 151 on one side of the head and 208 on one side of the body; (3) tuberous receptors were estimated to number 3,000-3,500 on one side of the head and 3,500-5,000 on one side of the body. The distribution of each receptor type is described. Each receptor is innervated by a single primary afferent. Electrosensory afferents have myelinated cell bodies in the ganglion of the anterior lateral line nerve (ALLN). The distribution of these ganglion cell diameters is strongly bimodal in Apteronotus and Eigenmannia: The smaller-diameter cells may be those which innervate ampullary electroreceptors, the larger-diameter tuberous electroreceptors. Transganglionic HRP transport techniques were used to determine the first-order connections of the anterior lateral line nerve in six species of gymnotiform fish. Small branches of the ALLN were labeled so as to determine the somatotopic organization in the PLLL. The PLLL is divided into four segments from medial to lateral, termed medial, centromedial, centrolateral, and lateral segments (Heiligenberg and Dye, '81). Representations of the head are found rostrally in each zone, and the trunk is mapped caudally in each zone. Thus there are four body maps in the PLLL. The medial segment receives ampullary input (Heiligenberg and Dye, '82) and maps the dorsoventral body axis mediolaterally, as does the tuberous centrolateral segment. The tuberous centromedial and lateral segments map the dorsoventral axis lateromedially. Thus the medial and centromedial segments meet belly to belly, the centromedial and centrolateral segments meet back to back, and the centrolateral and lateral segments meet belly to belly. Adjacent electrosensory maps within the PLLL are therefore always mirror images.

Efferent projections of the posterior lateral line lobe in gymnotiform fish.

The posterior lateral line lobe (PLLL) of gymnotoid fish has efferent projections to two midbrain regions: the nucleus praeeminentialis dorsalis (n.P.d.) and the torus semicircularis dorsalis (T.Sd.). Both ipsilateral and contralateral connections are present; the n.P. d. receives nearly equal input from both sides while the T.Sd. receives a stronger contralateral input. The PLLL projection to n.P.d. merely maps medial PLLL to ventral n.P.d. and lateral PLLL to dorsal n.P.d., thus preserving the separate topography and relative orientation of the four electrosensory maps found in the PLLL. Only PLLL pyramidal cells (basilar and nonbasilar pyramids) contribute to this projection. The four PLLL electrosensory maps converge onto T.Sd. so that they map the dorsal body surface onto medial T.Sd. and the ventral body surface onto lateral T.Sd. Pyramidal cells, spherical cells, and multipolar cells contribute to this projection. A small commissural connection links homologous segments of the PLLL; these fibers arise from polymorphic cells of the PLLL.

Laminar organization of the afferent and efferent systems of the torus semicircularis of gymnotiform fish: morphological substrates for parallel processing in the electrosensory system.

The torus semicircularis of Gymnotiform fish is an enlarged laminated midbrain structure which receives lemniscal input from electrosensory, mechanoreceptive lateral line, and auditory systems. The electrosensory input in confined to the dorsal torus, while the auditory and mechanoreceptive systems project to the ventral torus. Anterograde and retrograde techniques were used were used to determine the connections of the dorsal torus in Apteronotus and Eigenmannia. The dorsal torus can be divided into nine major laminae, each of which has distinct afferent and efferent connections. The dorsal torus receives five afferent inputs: (1) A contralateral topographic input from the posterior lateral line lobe (PLLL) projects to laminae III, V, VI, VII, VIIIB, and VIIID. (2) Eurydendroid cells of the caudal lobe of the cerebellum project contralaterally to lamina VIIIB. (3) A portion of the descending nucleus of V projects to laminae VIIIA, VIIIC, and IX. (4) Lamina I is a cap of fine myelinated fibers which may originate in the torus longitudinalis. They project to laminae II and III. (5) The ipsilateral optic tectum projects to the dorsal torus. The dorsal torus projects to six major targets: (1) Laminae VII, VIII, and IX project bilaterally to a lateral region of the diencephalon above n. preglomerulosus, herein named n. electrosensorius. An area below the dorsal thalamus receives a smaller ipsilateral projection. (2) Laminae II, V, VIvn, VII, VIII, and IX project topographically to the deeper laminae of the ipsilateral optic tectum. This projection is in spatial register with the visual map in the superficial layers of the tectum. (3) Lamina VIIID projects ipsilaterally to the lateral reticular formation. (4) All laminae other than I, VI, and VIIIB project topographically to ahe ipsilateral n. praeeminentialis, which provides a powerful descending projection to the PLLL. (5) Lamina IX projects to a dorsal pretectal area. (6) The ipsilateral inferior olive receives a projection from the dorsal torus.