Four neurons in the brain of the migratory locust were immunohistologically identified with an anti-met-enkephalin antiserum. The perikarya of two of these cells are located in the center of each of the two groups of lateral protocerebral neurosecretory cells. The fibres coming from these perikarya terminate in numerous immunoreactive ramifications visible at the periphery of both tractus I to the corpora cardiaca, through which pass the neurosecretory products of the pars intercerebralis. The other two cell bodies are located at the bases of the two optic lobes; their fibres enter the posterior part of the protocerebrum and ramify around the root of the nervus corporis cardiaci II, another area through which neurosecretory products pass. The topographic distribution of these met-enkephalin arborizations suggests that these four neurons may act a s neuromodulators of the activity of the major neurosecretory cells in the brain of this insect.

Axoplasm from the squid giant axon contains a soluble protein translocator that induces movement of microtubules on glass, latex beads on microtubules, and axoplasmic organelles on microtubules. We now report the partial purification of a protein from squid giant axons and optic lobes that induces these microtubule-based movements and show that there is a homologous protein in bovine brain. The purification of the translocator protein depended primarily on its unusual property of forming a high affinity complex with microtubules in the presence of a nonhydrolyzable ATP analog, adenylyl imidodiphosphate. The protein, once released from microtubules with ATP, migrates on gel filtration columns with an apparent molecular weight of 600 kilodaltons and contains 110-120 and 60-70 kilodalton polypeptides. This protein is distinct in molecular weight and enzymatic behavior from myosin or dynein, which suggests that it belongs to a novel class of force-generating molecules, for which we propose the name kinesin.

Axoplasmic vesicles were purified and observed to translocate on isolated microtubules in an ATP-dependent, trypsin-sensitive manner, implying that ATP-binding polypeptides essential for force generation were present on the vesicle surface. To identify these proteins [alpha 32P]8-azidoadenosine 5'-triphosphate ([alpha 32P]8-N3ATP), a photoaffinity analogue of ATP, was used. The results presented here identify and characterize a vesicle-associated polypeptide having a relative molecular mass of 292 kD that bound [alpha 32P]8-N3ATP. The incorporation of label is ultraviolet light-dependent and ATP-sensitive. Moreover, the 292-kD polypeptide could be isolated in association with vesicles or microtubules, depending on the conditions used, and the data indicate that the 292-kD polypeptide is similar to mammalian brain microtubule-associated protein 2 (MAP 2) for the following reasons: The 292-kD polypeptide isolated from either squid axoplasm or optic lobe cross-reacts with antiserum to porcine brain MAP 2. Furthermore, it purifies with taxol-stabilized microtubules and is released with salt. Based on these characteristics, the 292-kD polypeptide is distinct from the known force-generating molecules myosin and flagellar dynein, as well as the 110-130-kD kinesin-like polypeptides that have recently been described (Brady, S. T., 1985, Nature (Lond.), 317:73-75; Vale, R. D., T. S. Reese, and M. P. Sheetz, 1985b, Cell, 42:39-50; Scholey, J. M., M. E. Porter, P. M. Grissom, and J. R. McIntosh, 1985, Nature (Lond.), 318:483-486). Because the 292-kD polypeptide binds ATP and is associated with vesicles that translocate on purified MAP-free microtubules in an ATP-dependent fashion, it is therefore believed to be involved in vesicle-microtubule interactions that promote organelle motility.

Different antisera to the molluscan cardioexcitatory peptide FMRFamide, and its fragment, RFamide (Arg-Phe-NH2), label a distinct population of neurons in the optic lobe of the blowfly, Calliphora erythrocephala. Seven morphological types of RFamide/FMRFamide-like immunoreactive neurons could be distinguished in the optic lobes based on the locations of their cell bodies, their axonal projections and the distribution of their processes. Of these, two types could be resolved in their entire extent, the others were labeled only in their cell bodies and terminal processes or were partly obscured by other immunoreactive processes. The RF-like immunoreactive neurons in the optic lobes are of two main classes:(1) two types of large field projection neurons and (2) five types of local neurons. One type of projection neurons (five in each lobe) connects the entire projected retinal mosaic of the medulla and lobula in the optic lobe with protocerebral centres associated with the mushroom body calyx. The other type (2-3 invading each lobe) has cell bodies in the protocerebrum and contralateral processes invading optic lobes. Of the class of local neurons there are two amacrine RF-like immunoreactive neurons in each medulla. Each of these amacrines supplies the entire mosaic with fine processes. The remaining local RF-like immunoreactive neurons are present in relatively large numbers (one type in more than 2000 copies in each medulla) and-supply the medulla, lobula and lobula plate neuropils with fine varicose processes. In the medulla the RF-like immunoreactive processes are arranged in strict layers whereas in the lobula complex the distribution is diffuse. Electron microscopic immunocytochemistry, using both pre-embedding immuno peroxidase-antiperoxidase and post-embedding protein A-gold labeling, was employed for analysis of cytology and synaptic connections of RF-like immunoreactive neurons in the medulla. The varicosities of the processes of the large field projection neurons were not found to make chemical synapses with other neurons in the medulla. The spines of the RF-like immunoreactive processes of the large medulla amacrines, however, make pre- and postsynaptic contacts with other neural elements. Our findings indicate that an RFamide/FMRFamide-like substance may be used as a neurotransmitter or neuromodulator by optic lobe neurons of different types. The local and projection RF-like immunoreactive pathways probably play different roles in visual processing.

A neuropeptide related to the mammalian neuropeptide Y (NPY) is present in various neurosecretory cells (NSC) of the cephalic and thoracic nervous systems of the insect Locusta migratoria. Immunoreactive perikarya are detected in the protocerebrum, tritocerebrum, optic lobes and the suboesophageal and thoracic ganglia. They give rise to many immunoreactive processes that ramify extensively throughout the neuropiles. In the brain, prominent axon bundles tightly surround the tractus I to the corpora cardiaca. This fiber pattern suggests that the NPY-like substance may have a neuromodulator and/or neurotransmitter function. This substance may also have a neurohormonal role, since some immunoreactive tracts penetrate into neurohaemal organs via the nervi corporis cardiaci II and the thoracic median nerves. NCS containing NPY-like neuropeptide also display an FMRFamide-like immunoreactivity (except for the abdominal part of the metathoracic ganglion). NPY or FMRFamide antisera are not inactivated after preabsorption with FMRFamide or NPY, respectively. It might therefore be inferred that in locust NSC these two antisera recognize two distinct antigenic sites belonging either to a large polypeptide, or to two distinct neuropeptides.

The achaete-scute complex (AS-C) comprises five genetic regions: achaete, scute (sc) alpha, lethal of sc, sc beta and sc gamma. Each region promotes the determination and positional specification of different, but partially overlapping, subsets of neural elements of Drosophila. In this work, we report a molecular characterization of the sc gamma region. It comprises 22 kb of DNA and contains two transcription units, only one of which, named asense (ase), seems involved in neurogenesis. ase encodes a protein that shares with other three AS-C proteins a domain containing a helix--loop--helix motif characteristic of a group of DNA-binding proteins. In the embryo, ase is expressed in neural precursor cells, a pattern consistent with the known requirement of sc gamma for the development of the larval nervous system. In late third-instar larvae, the gene is expressed in developing structures of the central nervous system (CNS), namely the anlagen of the optic lobes and in many cells, including neuroblasts, of the central brain and ventral ganglia. Its removal leads to anatomical defects in the adult optic lobes. This is the first demonstration of a role for the AS-C in the development of the adult CNS.

Dopamine-immunoreactive (DA-IR) neurons were mapped in detail in the visual system of the blowfly, Calliphora erythrocephala. Three types of DA-IR neurons could be identified in the optic lobes. One type constitutes a population of several thousand columnar small field amacrine neurons in the second neuropil region, the medulla. The other two types are large field projection neurons innervating the next, more central, synaptic region comprising the lobula and the lobula plate, as well as centres of the midbrain. Their cell bodies are located latero-ventrally in the brain. No DA-IR neurons were seen in the most peripheral visual synaptic neuropil, the lamina. The two types of projection neurons form overlapping wide field arborizations in the lobula and lobula plate and cannot be distinguished from each other in this region. Their central connections are different, however. One type of projection neuron, BOD1, consists of two neurons that bilaterally connect the optic lobes and neuropil on each side of the oesophageal foramen in the posterior protocerebrum. The other type, BOD2, also consists of two bilateral neurons similar to BOD1, but with their central processes posteriorly in the lateral protocerebrum. The amacrine DA-IR neurons form lateral processes in three layers of the medulla synaptic neuropil. These neurons were also investigated by means of electron microscopical immunocytochemistry. They contain predominantly clear vesicles, but a few dense core vesicles could be resolved. The synaptic connections of the DA-IR amacrines suggest that they form centrifugal feedback circuits between the inner and the outer portion of the medulla. The present results indicate that dopamine may be a neurotransmitter in functionally different classes of neurons of the blowfly visual system: amacrines and projection neurons.

Four neurons in the brain of the migratory locust were immunohistologically identified with an anti-met-enkephalin antiserum. The perikarya of two of these cells are located in the center of each of the two groups of lateral protocerebral neurosecretory cells. The fibres coming from these perikarya terminate in numerous immunoreactive ramifications visible at the periphery of both tractus I to the corpora cardiaca, through which pass the neurosecretory products of the pars intercerebralis. The other two cell bodies are located at the bases of the two optic lobes; their fibres enter the posterior part of the protocerebrum and ramify around the root of the nervus corporis cardiaci II, another area through which neurosecretory products pass. The topographic distribution of these met-enkephalin arborizations suggests that these four neurons may act a s neuromodulators of the activity of the major neurosecretory cells in the brain of this insect.

The brains of 43 patients, some with various neurological disorders, other controls, were examined for herpes simplex virus (HSV) antigen using immunoperoxidase technique. The three patients with herpes simplex encephalitis shared a pattern of staining, consistent with that reported previously. However, of the other 40 patients, only two (one a patient with Alzheimer's disease, the other a control patient) showed areas of brain positive for HSV antigen (VA). In the patient with Alzheimer's disease VA was present within nerve and glial cells of the amygdala, within oligodendrocytes of the optic and olfactory tracts and in macrophages within the temporal cortex hippocampus and cerebellum. In the control patient VA was seen only in oligodendrocytes of optic chiasma and olfactory tract. The scarcity of these findings suggests "coincidental disease" processes within these two patients and means that any hypothesis implicating HSV as an aetiological agent in degenerative disease must still remain extremely speculative.