Development of an identified serotonergic neuron in the antennal lobe of the moth and effects of reduction in serotonin during construction of olfactory glomeruli

Each olfactory (antennal) lobe of the moth Manduca sexta contains a single serotonin (5-HT) immunoreactive neuron whose processes form tufted arbors in the olfactory glomeruli. To extend our present understanding of the intercellular interactions involved in glomerulus development to the level of an individual, identified antennal lobe neuron, we first studied the morphological development of the 5-HT neuron in the presence and absence of receptor axons. Development of the neuron's glomerular tufts depends, as it does in the case of other multiglomerular neurons, on the presence of receptor axons. Processes of the 5-HT neuron are excluded from the region in which the initial steps of glomerulus construction occur and thus cannot provide a physical scaffolding on which the array of glomeruli is organized. Because the neuron's processes are present in the antennal lobe neuropil throughout postembryonic development, 5-HT could provide signals that influence the pattern of development in the lobe. By surgically producing 5-HT-depleted antennal lobes, we also tested the importance of 5-HT in the construction of olfactory glomeruli. Even in the apparent absence of 5-HT, the glomerular array initiated by the receptor axons was histologically normal, glial cells migrated to form glomerular borders, and receptor axons formed terminal branches in their normal region within each glomerulus. In some cases, 5-HT-immunoreactive processes from abnormal sources entered the lobe and formed the tufted intraglomerular branches typical of most antennal lobe neurons, suggesting that local cues strongly influence the branching patterns of developing antennal lobe neurons. © 1995 John Wiley & Sons, Inc.     

Evidence of Increased Oxidative Damage in Both Sporadic and Familial Amyotrophic Lateral Sclerosis

Abstract: Some cases of autosomal dominant familial amyotrophic lateral sclerosis (FALS) are associated with mutations in the gene encoding Cu/Zn superoxide dismutase (SOD1), suggesting that oxidative damage may play a role in ALS pathogenesis. To further investigate the biochemical features of FALS and sporadic ALS (SALS), we examined markers of oxidative damage to protein, lipids, and DNA in motor cortex (Brodmann area 4), parietal cortex (Brodmann area 40), and cerebellum from control subjects, FALS patients with and without known SOD mutations, SALS patients, and disease controls (Pick's disease, progressive supranuclear palsy, diffuse Lewy body disease). Protein carbonyl and nuclear DNA 8-hydroxy-2'-deoxyguanosine (OH⁸dG) levels were increased in SALS motor cortex but not in FALS patients. Malondialdehyde levels showed no significant changes. Immunohistochemical studies showed increased neuronal staining for hemeoxygenase-1, malondialdehyde-modified protein, and OH⁸dG in both SALS and FALS spinal cord. These studies therefore provide further evidence that oxidative damage may play a role in the pathogenesis of neuronal degeneration in both SALS and FALS.     

Headspace gas chromatography with capillary column for urine alcohol determination

A headspace gas chromatographic method using a fused-silica capillary column Poraplot Q has been developed and validated for the detection and quantification of ethanol in urine. Under optimized conditions, ethanol was properly separated from acetaldehyde, acetone, isopropanol, methanol and n-propanol. Limits of detection (LODs) and quantification (LOQs) were 0.008 and 0.010 g/l, respectively. The precision studies within-run and between-run, using spiked urine samples (0.08, 0.8 and 2.0 g/l) showed maximum coefficients of variation 5.9 and 6.5%, respectively. Results of ethanol recovery varied from 91.6±0.8 to 103.3±1.8% over the concentration range from 0.01 to 3.20 g/l. The method was appropriate for the detection of ethanol in urine samples. This matrix can be used for monitoring alcohol abuse in the workplace and used in alcohol rehabilitation programs.     

Nature and site of action of endogenous nitric oxide in vasculature of isolated pig lungs

Cremona, George, Tim Higenbottam, Motoshi Takao, Edward A. Bower, and Leslie W. Hall. Nature and site of action of endogenousnitric oxide in vasculature of isolated pig lungs. J. Appl. Physiol. 82(1): 23-31, 1997.The site ofaction of endogenous and exogenous nitric oxide (NO) in isolated piglungs was investigated by using arterial, double, and venous occlusion,which allowed precapillary, postcapillary, and venous segments to bepartitioned into arterial, precapillary, postcapillary, and venoussegments. N^G-nitro-L-arginine(L-NNA;10⁵ M) increased resistancein the arterial (35 ± 6.6%, P = 0.003), precapillary (39.3 ± 5.1%,P = 0.001), and venous (18.3 ± 4.8%, P = 0.01) segments,respectively. Sodium nitroprusside(10⁵ M) and NO (80 parts/million) reversed the effects ofL-NNA. Total pulmonary vascularresistance fell with increasing flow, due to a fall in precapillaryresistance and dynamic resistance, and was significantlylower than mean total resistance.L-NNA increased the resistancesbut did not alter the pattern of the pressure-flow relationships. It isconcluded that, in isolated pig lungs, the effect of endogenous NOseems to be dependent on flow in the arterial segment and independentof flow in the precapillary segment, but variation of its release doesnot appear to be fundamental to accommodation to changes in steadyflow.

     

Isolation of the human chromosome 22q telomere and its application to detection of cryptic chromosomal abnormalities

A number of human telomeres have been successfully cloned using a modified yeast artificial chromosome (YAC) vector (half-YAC) cloning strategy, but to date, human chromosome 22q has not been identified by this approach. We used an alternative approach of genomic walking, starting from a subtelomeric sequence, TelBam3.4, present on a number of human chromosomes including 22q. This approach was successful in the development of a cosmid contig representing the terminal 140 kb of human chromosome 22q, providing telomeric closure of the genetic and physical maps for 22q. The most distal region of the contig contains subtelomeric repeats which crosshybridize to a number of chromosomes, while the proximal sequences are unique for 22q. The unique sequence cosmid was used as a 22qter-specific probe for fluorescence in situ hybridization (FISH) analysis, which confirmed that this cosmid was distal to the most telomeric marker previously available for chromosome 22. In addition, this cosmid was used to document a 22q terminal deletion that was not detectable by conventional cytogenetic analysis. Unique telomere-specific FISH probes such as this one will have significant diagnostic value in the detection of cryptic deletions and translocations in patients with unexplained mental retardation and other patient populations. Received: 21 November 1995     

Localization of Two Potassium Channel β Subunit Genes, KCNA1B and KCNA2B

The gating properties and current amplitudes of mammalian voltage-activatedShakerpotassium channels are modulated by at least two associated β subunits (Kvβ1.1 and Kvβ1.2). The human Kvβ1.1 gene (KCNA1B) resides on chromosome 3, as indicated by somatic cell hybrid mapping. More precise localization of KCNA1B to 3q26.1 was obtained with fluorescencein situhybridization (FISH) and was corroborated by PCR screening of the CEPH YAC library. The human Kvβ1.2 gene (KCNA2B) resides on chromosome 1, as indicated by somatic cell hybrid mapping, and has been localized by FISH to 1p36.3.     

Mapping of theARIXHomeodomain Gene to Mouse Chromosome 7 and Human Chromosome 11q13

The recently described homeodomain protein ARIX is expressed specifically in noradrenergic cell types of the sympathetic nervous system, brain, and adrenal medulla. ARIX interacts with regulatory elements of the genes encoding the noradrenergic biosynthetic enzymes tyrosine hydroxylase and dopamine β-hydroxylase, suggesting a role for ARIX in expression of the noradrenergic phenotype. In the study described here, the mouse and human ARIX genes are mapped. Using segregation analysis of two panels of mouse backcross DNA, mouseArixwas positioned approximately 50 cM distal to the centromere of chromosome 7, nearHbb.HumanARIXwas positioned through analysis of somatic cell hybrids and fluorescencein situhybridization of human metaphase chromosomes to chromosome 11q13.3–q13.4. These map locations extend and further define regions of conserved synteny between mouse and human genomes and identify a new candidate gene for inherited developmental disorders linked to human 11q13.     

Analysis of ssb mutations in vivo implicates SSB protein in two distinct pathways of SOS induction and in recombinational DNA repair

Site-directed mutations in the Escherichia coli ssb gene were tested for the ability to complement a chromosomal ssb deletion for viability, and only the ssb W54→G mutation failed to do so at the pSC101 copy level. Non-aromatic amino acid substitutions for SSB Trp-54 ( ssb W54→L and ssb W54→S) produced the greatest effects on in vivo protein function including altered marker linkage subsequent to generalized transduction, extreme UV sensitivity, and a lack of ability to support SOS induction. Additionally, the ssb-113 ( ssb P176→S) mutation demonstrated the existence of both uvrA -dependent and uvrA -independent components of SOS induction. Although nucleotide excision repair appeared unaffected by alterations in the SSB protein, the mutational analysis suggests a direct role for SSB in recombinational repair.