Nitric oxide acts directly in the presynaptic neuron to produce long-term potentiation in cultured hippocampal neurons

Nitric oxide (NO) has been proposed to act as a retrograde messenger during long-term potentiation (LTP) in the CA1 region of hippocampus, but the inaccessibility of the presynaptic terminal has prevented a definitive test of this hypothesis. Because both sides of the synapse are accessible in cultured hippocampal neurons, we have used this preparation to investigate the role of NO. We examined LTP following intra- or extracellular application of an NO scavenger, an inhibitor of NO synthase, and a membrane-impermeant NO donor that releases NO only upon photolysis with UV light. Our results indicate that NO is produced in the postsynaptic neuron, travels through the extracellular space, and acts directly in the presynaptic neuron to produce long-term potentiation, supporting the hypothesis that NO acts as a retrograde messenger during LTP.     

The Impact of WARC-79 on Space Applications

Prior to the 1979 World Administrative Radio Conference (WARC-79), no frequency bands were allocated for remotesensing measurements. Actions taken by the WARC insure that frequencies will be available for such use, and that operations can be conducted without harmful interference on a worldwide basis for the benefit of all nations. Allocations employed for transfer of scientific data from spacecraft in all regions of space from near-Earth orbit to deep-space planetary ranges were significantly improved. New global allocations for Earth exploration-satellites will permit worldwide acquisition of Earth exploration data both via direct transmission and via relay satellites. New allocations for meteorological satellite data transmission will permit wide-band applications such as direct reception of highresolution picture data by users. Satellite-aided search and rescue systems will benefit from WARC decisions to allocate frequencies exclusively for emergency radiobeacon systems using space techniques. Bands to provide links between the satellite and Earth were designated for distress and safety operations. Time and frequency services with accuracies in the 10- to 50-ps range, needed to meet future system requirements for precise time and frequency information, will be possible because of WARC actions to allocate frequency bands with suitable bandwidth for these services. The search for communications from extraterrestrial intelligence was afforded a degree of protection near several spectral lines of basic physical interest.     

The Design and Planning of Feeder Links to Broadcasting Satellites

A feeder link is the portion of a broadcasting-satellite system which provides the connection from the earth to the broadcasting satellite. Quality objectives for feeder links are normally well above the corresponding objectives for downlinks. The parameters which affect signal quality are examined. It is shown that the greatest control over theC/Nratio lies with the selection of suitable values for the diameter of the feeder link transmit antenna and the power of its associated transmitter. Three mechanisms are available to combat interference between feeder links: discrimination resulting from the feeder link transmit antenna pattern, discrimination derived from the satellite receive antenna pattern, and discrimination due to the use of cross-polarized signals. The use of these mechanisms to create a workable feeder link plan is developed in the paper. There are a number of desirable objectives that can be established for a feeder link plan in addition to the obvious need to meet signal quality (C/N) and interference (C/I) requirements. A realizable set of objectives is presented along with the approaches used at the ITU Region 2 planning conference to create a satisfactory plan. The technical parameters which must be agreed on in order to develop a feeder link plan are summarized, and the values chosen for the Region 2 plan are presented.     

The mammalian staufen protein localizes to the somatodendritic domain of cultured hippocampal neurons: implications for its involvement in mRNA transport

UDP-N-acetylglucosamine:alpha-3-D-mannoside beta-1, 2-N-acetylglucosaminyltransferase I (GnT I) is a key enzyme in the synthesis of Asn-linked complex and hybrid glycans. Studies on mice with a null mutation in the GnT I gene have indicated that N-glycans play critical roles in mammalian morphogenesis. This paper presents studies on N-glycans during the development of the nematode Caenorhabditis elegans. We have cloned cDNAs for three predicted C. elegans genes homologous to mammalian GnT I (designated gly-12, gly-13, and gly-14). All three cDNAs encode proteins (467, 449, and 437 amino acids, respectively) with the domain structure typical of previously cloned Golgi-type glycosyltransferases. Expression in both insect cells and transgenic worms showed that gly-12 and gly-14, but not gly-13, encode active GnT I. All three genes were expressed throughout worm development (embryo, larval stages L1-L4, and adult worms). The gly-12 and gly-13 promoters were expressed from embryogenesis to adulthood in many tissues. The gly-14 promoter was expressed only in gut cells from L1 to adult developmental stages. Transgenic worms that overexpress any one of the three genes show no obvious phenotypic defects. The data indicate that C. elegans is a suitable model for further study of the role of complex N-glycans in development.     

Multiplexed time-lapse photomicrography of cultured cells

A system of cinemicrography has been developed in which a single microscope and 16 mm camera are multiplexed to produce a time-lapse photographic record of many fields simultaneously. The field coordinates and focus are selected via a control console and entered into the memory of a dedicated microcomputer; they are then automatically recalled in sequence, thus permitting the photographing of additional fields in the interval between exposures of any given field. Sequential exposures of each field are isolated in separate sections of the film by means of a specially designed random-access camera that is also controlled by the microcomputer. The need to unscramble frames is thereby avoided, and the developed film can be directly analysed.