Identificación de una nueva mutación como causa del síndrome de Lesch-Nyhan en una familia peruana: utilidad del examen molecular para el consejo genético

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Mass spectrometric analysis of FMRFamide-like immunoreactive neurons in the prothoracic and subesophageal ganglion of Periplaneta americana

MALDI-TOF mass spectrometry combined with immunocytochemistry and retrograde labeling, was used to study the expression pattern and morphology of Pea-FMRFamide-related peptides in single neurons of the prothoracic ganglion and the subesophageal ganglion (SEG) of the American cockroach Periplaneta americana. In contrast to the postero-lateral cells (PLCs) of the meta- and mesothoracic ganglion, the prothoracic FMRFamide-related peptides expressing neurons not only extend in the posterior median nerve but also in an anterior median nerve, which is described herein. The peptidome of the prothoracic PLCs is identical with that of the meso- and metathoracic neurons, respectively. In this study, we identified a truncated form of Pea-FMRFa-24 which was found to be more abundant than the peptide originally designated as Pea-FMRF-24. FMRFamide-related peptides expressing postero-lateral cells were also detected in the labial neuromere of the SEG. Although their projection could not be solved, mass spectrometric analyses revealed the same peptide complement in these neurons as found in the thoracic postero-lateral cells. In all neurons which we studied no co-localized peptides of other peptide families were observed.

Differential Receptor Activation by Cockroach Adipokinetic Hormones Produces Differential Effects on Ion Currents, Neuronal Activity, and Locomotion

Adipokinetic hormone (AKH) peptides in insects serve the endocrine control of energy supply. They also produce, however, neuronal, vegetative, and motor effects, suggesting that AKHs orchestrate adaptive behavior by multiple actions. We have cloned, for Periplaneta americana, the AKH receptor to determine its localization and, based on current measurements in neurons and heterologous expression systems, the mechanisms of AKH actions. Apart from fat body, various neurons express the AKH receptor, among them abdominal dorsal unpaired median (DUM) neurons, which release the biogenic amine octopamine. They are part of the arousal system and are involved in the control of circulation and respiration. Both the two Periplaneta AKHs activate the Gspathway, and AKH I also potently activates Gq. AKH I and—with much less efficacy—AKH II accelerate spiking of DUM neurons through an increase of the pacemaking Ca2+current. Because the AKHs are released from the corpora cardiaca into the hemolymph, they must penetrate the blood-brain barrier for acting on neurons. That this happens was shown electrophysiologically by applying AKH I to an intact ganglion. Systemically injected AKH I stimulates locomotion potently in striking contrast to AKH II. This behavioral difference can be traced back conclusively to the different effectiveness of the AKHs on the level of G proteins. Our findings also show that AKHs act through the same basic mechanisms on neuronal and nonneuronal cells, and they support an integration of metabolic and neuronal effects in homoeostatic mechanisms.

Unique accumulation of neuropeptides in an insect: FMRFamide-related peptides in the cockroach, Periplaneta americana

FMRFamides belong to the most extensively studied neuropeptides in invertebrates and exhibit diverse physiological effects on different target organs, such as muscles, intestine and the nervous system. This study on the American cockroach confirms for the first time that extended FMRFamides occur in non-dipteran insects. By means of tandem mass spectrometry, these neuropeptides were structurally elucidated, and sequence information was used for subsequent cloning of the cockroach FMRFamide gene. This precursor gene encodes for 24 putative peptides and shows sufficient similarity with the Drosophila FMRFamide gene. Of the 24 peptides, 23 were detected by mass spectrometric methods; it is the highest number of neuropeptide forms shown to be expressed from a single precursor in any insect. The expression was traced back to single neurons in the thoracic ganglia. The unique accumulation of these FMRFamide-related peptides in thoracic perisympathetic organs provides the definite evidence for a tagma-specific distribution of peptidergic neurohormones in neurohaemal release sites of the insect CNS. Excitatory effects of the cockroach FMRFamides were observed on antenna-heart preparations. In addition, the newly described FMRFamides reduce the spike frequency of dorsal-unpaired median neurons and reduce the intracellular calcium concentration, which may affect the peripheral release of the biogenic amine octopamine.

Duplex-ultrasonographic evaluation of the common carotid artery in the resting, sedated and anesthetized horse

The aim of this study was to determine the blood flow in the carotid artery during halothane anaesthesia by means of duplex-sonography. Seventeen warm blood horses were evaluated in dorsal and lateral recumbency and the results were compared with the values of the same horses resting and under sedation. The cross sectional area of the vessels, the time-averaged maximal blood velocity, time-averaged maximal blood flow and the resistance index were determined and the flow profile was evaluated. During halothane anesthesia the total blood flow shows a significant increase which is not dependent on the positioning of the horse. Mean blood velocity is decreased by sedation and significantly increased during anesthesia. Reduced peripheral resistance is expressed by a decline of the resistance index. After sedation and during recumbency there is an increase in diameter of the carotid artery.

Identification of a new Lesch-Nyhan syndrome mutation (HPRTBrasil) and analysis of potentially heterozygous females

The mutation in the hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene has been determined in two brothers affected with Lesch-Nyhan syndrome. Female members of the family who are at risk for being heterozygous carriers of the HPRT mutation were also studied to determine whether they carry the mutation. DNA sequencing revealed that the boys' mother is heterozygous for the mutation in her somatic cells, but that three maternal aunts are not heterozygous. Such carrier information is important for the future pregnancy plans of at-risk females. The mutation, an A-->T transversion at cDNA base 590 (590A-->T), results in an amino acid change of glutamic acid to valine at codon 197, and has not been reported previously in a Lesch-Nyhan syndrome male. This mutation is designated HPRTBrasil.

Periviscerokinin-like immunoreactivity in the nervous system of the American cockroach

A highly specific polyclonal antiserum has been raised against periviscerokinin, the first neuropeptide isolated from the perisympathetic organs of insects (Predel et al. 1995). In this study, two different neuronal systems with periviscerokinin-like immunoreactivity were distinguished in the central nervous system of the American cockroach: (1) An intrinsic neuronal network, restricted to the head-thoracic region, was formed by intersegmental projecting neurons of the brain, suboesophageal ganglion and metathoracic ganglion. In addition, groups of local interneurons occurred in the proto- and tritocerebrum. (2) A typical neurohormonal system was stained exclusively in the abdomen; it was represented by abdominal perisympathetic organs which were supplied by three cell clusters located in each unfused abdominal ganglion. As revealed by nickel backfills, most neurons with axons entering the perisympathetic organs contained a periviscerokinin-like peptide. Immunoreactive fibres left the perisympathetic organs peripherally, innervated the hyperneural muscle and ran via the link nerves/segmental nerves to the heart and segmental vessels. All visceral muscles innervated by periviscerokinin-immunoreactive fibres were shown to be sensitive to periviscerokinin, whereas the hindgut gave no specific response to this peptide.

Anatomy of neurons crossing the tritocerebral commissures of the cockroach Periplaneta americana (Blattaria)

The neuronal connections of the tritocerebral commissures of Periplaneta americana were studied in the brain-suboesophageal ganglion complex and the stomatogastric nervous system by means of heavy metal iontophoresis through cut nerve ends followed by silver intensification. The tritocerebral commissure 1 (Tc1) contains mainly the processes of the subpharyngeal nerve (Spn) whose neurons are located in both tritocerebral lobes and in the frontal ganglion. Some neurons of the frontal ganglion project through the Tc1 to the contralateral tritocerebrum. A few fibers in this commissure were observed projecting to the protocerebrum and the suboesophageal ganglion. There are tritocerebral neurons which pass through the Tc1 or the tritocerebral commissure 2 (Tc2) and extend on into the stomatogastric nervous system. One axon of a descending giant neuron appears in the Tc2. This neuron lies in the tritocerebrum and connects the brain to the contralateral side of the ventral nerve cord. In addition, sensory fibers of the labral nerve (Ln) traverse both commissures to the opposite tritocerebrum. The anatomical and physiological relevance of the identified neuronal pathways is discussed.

Identification of neuronal pathways between the stomatogastric nervous system and the retrocerebral complex of the cockroach Periplaneta americana (L.)

The neuronal pathways connecting the stomatogastric nervous system with the retrocerebral complex of the cockroach, Periplaneta americana, were investigated by means of axonal cobalt chloride iontophoresis. Somata in the hypocerebral ganglion and in the nervus recurrens sending their axons to different parts of the stomatogastric nervous system were traced. Some axons in the oesophageal nerve arise from large perikarya in the anterior part of the pars intercerebralis and pass via the NCCI to the corpora cardiaca and the oesophageal nerve. The form a profuse dendritic tree in the protocerebrum. Fibers of the NCC I and NCC II as well as the NCA I and NCA II enter the stomatogastric nervous system via the hypocerebral ganglion.

The neuronal connections of the frontal ganglion of the cockroach Periplaneta americana. A histological and iontophoretical study

The frontal ganglion of the cockroach Periplaneta americana was studied histologically and its neuronal pathways were mapped by use of axonal cobalt iontophoresis. Neurons and fiber tracts of the frontal ganglion are directly linked with different regions of the central nervous system (tritocerebrum, protocerebrum, subesophageal ganglion) and with the more caudal parts of the stomatogastric nervous system (hypocerebral ganglion, nervus oesophagei).