Two novel Xenopus homologs of mammalian LP(A1)/EDG-2 function as lysophosphatidic acid receptors in Xenopus oocytes and mammalian cells

Lysophosphatidic acid (LPA) induces diverse biological responses in many types of cells and tissues by activating its specific G protein-coupled receptors (GPCRs). Previously, three cognate LPA GPCRs (LP(A1)/VZG-1/EDG-2, LP(A2)/EDG-4, and LP(A3)/EDG-7) were identified in mammals. By contrast, an unrelated GPCR, PSP24, was reported to be a high affinity LPA receptor in Xenopus laevis oocytes, raising the possibility that Xenopus uses a very different form of LPA signaling. Toward addressing this issue, we report two novel Xenopus genes, xlp(A1)-1 and xlp(A1)-2, encoding LP(A1) homologs (approximately 90% amino acid sequence identity with mammalian LP(A1)). Both xlp(A1)-1 and xlp(A1)-2 are expressed in oocytes and the nervous system. Overexpression of either gene in oocytes potentiated LPA-induced oscillatory chloride ion currents through a pertussis toxin-insensitive pathway. Injection of antisense oligonucleotides designed to inhibit xlp(A1)-1 and xlp(A1)-2 expression in oocytes eliminated their endogenous response to LPA. Furthermore, retrovirus-mediated heterologous expression of xlp(A1)-1 or xlp(A1)-2 in B103 rat neuroblastoma cells that are unresponsive to LPA conferred LPA-induced cell rounding and adenylyl cyclase inhibition. These results indicate that XLP(A1)-1 and XLP(A1)-2 are functional Xenopus LPA receptors and demonstrate the evolutionary conservation of LPA signaling over a range of vertebrate phylogeny.

Physician-patient dialogue and clinical evaluation of erectile dysfunction

Erectile dysfunction affects 31% to 52% of all men. Although considerable advances have been made in the diagnosis and management of erectile dysfunction, the inadequate knowledge of erectile dysfunction by health care providers still precludes them from initiating candid discussions with their patients. This article provides the health care professional with the ability to establish comfortable doctor-patient dialogue and to clinically evaluate erectile dysfunction in a goal-directed manner. The goal of evaluation is to find the appropriate treatment for the individual, dictated primarily by factors like the patients' preferences, comfort, cost, and the availability of treatment modalities.

The mouse lp(A3)/Edg7 lysophosphatidic acid receptor gene: genomic structure, chromosomal localization, and expression pattern

The extracellular signaling molecule, lysophosphatidic acid (LPA), mediates proliferative and morphological effects on cells and has been proposed to be involved in several biological processes including neuronal development, wound healing, and cancer progression. Three mammalian G protein-coupled receptors, encoded by genes designated lp (lysophospholipid) receptor or edg (endothelial differentiation gene), mediate the effects of LPA, activating similar (e.g. Ca(2+) release) as well as distinct (neurite retraction) responses. To understand the evolution and function of LPA receptor genes, we characterized lp(A3)/Edg7 in mouse and human and compared the expression pattern with the other two known LPA receptor genes (lp(A1)/Edg2 and lp(A2)/Edg4non-mutant). We found mouse and human lp(A3) to have nearly identical three-exon genomic structures, with introns upstream of the coding region for transmembrane domain (TMD) I and within the coding region for TMD VI. This structure is similar to lp(A1) and lp(A2), indicating a common ancestral gene with two introns. We localized mouse lp(A3) to distal Chromosome 3 near the varitint waddler (Va) gene, in a region syntenic with the human lp(A3) chromosomal location (1p22.3-31.1). We found highest expression levels of each of the three LPA receptor genes in adult mouse testes, relatively high expression levels of lp(A2) and lp(A3) in kidney, and moderate expression of lp(A2) and lp(A3) in lung. All lp(A) transcripts were expressed during brain development, with lp(A1) and lp(A2) transcripts expressed during the embryonic neurogenic period, and lp(A3) transcript during the early postnatal period. Our results indicate both overlapping as well as distinct functions of lp(A1), lp(A2), and lp(A3).

The LPA receptors

Lysophosphatidic acid (LPA) is a growth factor-like lipid that produces many cellular responses. These responses, including actin cytoskeletal rearrangements, cell proliferation and inhibition of gap junction communication, have been documented in many cell types over the last 2 decades. Both non-receptor and receptor-mediated mechanisms had been implicated to explain these responses. A clear advance in this field was the cloning and functional identification of LPA receptors, and there are currently three high-affinity members, LPA1, LPA2 and LPA3 (synonymous with orphan receptor names edg-2, edg-4 and edg-7, respectively). Here we review the gene structure, expression and functions of LPA receptors. We also discuss the in vivo roles mediated by a single LPA receptor type, based on studies of the nervous system, a major locus of LPA receptor expression.

Hahella chejuensis gen. nov., sp. nov., an extracellular-polysaccharide-producing marine bacterium

A bacterial strain, designated 96CJ10356T, which produced abundant extracellular polysaccharides and red pigment was isolated from marine sediment collected from Marado, Cheju Island, Republic of Korea. The organism is Gram-negative, aerobic, rod-shaped and motile. Growth was not observed in the absence of NaCl, and was optimal at an NaCl concentration of 2%. The strain contained oxidase and catalase, and was able to hydrolyse aesculin and gelatin. The major cellular fatty acids were saturated or monounsaturated straight-chain fatty acids. An almost complete 16S rDNA sequence of the test strain was determined. Phylogenetic analysis based on the neighbour-joining and Fitch-Margoliash methods indicated that the organism formed a distinct phyletic line within the gamma Proteobacteria. This relationship was also supported by sequence comparison, as no valid bacterial species showed more than 90% sequence homology with the isolate. It is clear from polyphasic evidence that the isolate merits the status of genus in the gamma subclass of the Proteobacteria, and the name Hahella chejuensis gen. nov., sp. nov. is proposed for the marine isolate 96CJ10356T (= KCTC 2396T = IMSNU 11157T).

Arthrobacter siderocapsulatus Dubinina and Zhdanov 1975AL is a later subjective synonym of Pseudomonas putida (Trevisan 1889) Migula 1895AL

The taxonomic position of Arthrobacter siderocapsulatus Dubinina and Zhdanov 1975AL was investigated using 16S rDNA, fatty acid and phenotypic analyses. The type strain (NCIMB 11286T) showed 99.85% 16S rDNA similarity to the type strain of Pseudomonas putida. Phenotypic properties of the two strains were compared using API 20NE and BIOLOG kits. Identical reactions were recorded for all tests, except for assimilation of malonic acid. The two strains also showed almost identical cellular fatty acid profiles. On the basis of evidence presented in this and earlier studies, it is proposed that Arthrobacter siderocapsulatus is a later subjective synonym of Pseudomonas putida (Trevisan 1889) Migula 1895AL.

Pancreatic endocrine tumors

Pancreatic endocrine tumors are rare but have long held a fascination for clinicians because of the physiologic derangements that they can cause, and the dramatic corrections that can be achieved by appropriate management. In the year reviewed in this article, the literature again demonstrated the ongoing interest and research in this area. In particular, the areas of gastrinoma, insulinoma, and multiple endocrine neoplasia type 1 have received careful attention.

Lysophosphatidic acid (LPA) is a novel extracellular regulator of cortical neuroblast morphology

During cerebral cortical neurogenesis, neuroblasts in the ventricular zone (VZ) undergo a shape change termed "interkinetic nuclear migration" whereby cells alternate between fusiform and rounded morphologies. We previously identified lp(A1), the first receptor gene for a signaling phospholipid called lysophosphatidic acid (LPA) and showed its enriched expression in the VZ. Here we report that LPA induces changes in neuroblast morphology from fusiform to round in primary culture, accompanied by nuclear movements, and formation of f-actin retraction fibers. These changes are mediated by the activation of the small GTPase, Rho. In explant cultures, where the cerebral cortical architecture remains intact, LPA not only induces cellular and nuclear rounding in the VZ, but also produces an accumulation of rounded nuclei at the ventricular surface. Consistent with a biological role for these responses, utilization of a sensitive and specific bioassay indicates that postmitotic neurons can produce extracellular LPA. These results implicate LPA as a novel factor in cortical neurogenesis and further implicate LPA as an extracellular signal from postmitotic neurons to proliferating neuroblasts.

Lysophosphatidic acid receptors

Lysophosphatidic acid (LPA) is a simple bioactive phospholipid with diverse physiological actions on many cell types. LPA induces proliferative and/or morphological effects and has been proposed to be involved in biologically important processes including neurogenesis, myelination, angiogenesis, wound healing, and cancer progression. LPA acts through specific G protein-coupled, seven-transmembrane domain receptors. To date, three mammalian cognate receptor genes, lp(A1)/vzg-1/Edg2, lp(A2)/Edg4, and lp(A3)/Edg7, have been identified that encode high-affinity LPA receptors. Here, we review current knowledge on these LPA receptors, including their isolation, function, expression pattern, gene structure, chromosomal location, and possible physiological or pathological roles.

Requirement for the lpA1 lysophosphatidic acid receptor gene in normal suckling behavior

Although extracellular application of lysophosphatidic acid (LPA) has been extensively documented to produce a variety of cellular responses through a family of specific G protein-coupled receptors, the in vivo organismal role of LPA signaling remains largely unknown. The first identified LPA receptor gene, lp(A1)/vzg-1/edg-2, was previously shown to have remarkably enriched embryonic expression in the cerebral cortex and dorsal olfactory bulb and postnatal expression in myelinating glia including Schwann cells. Here, we show that targeted deletion of lp(A1) results in approximately 50% neonatal lethality, impaired suckling in neonatal pups, and loss of LPA responsivity in embryonic cerebral cortical neuroblasts with survivors showing reduced size, craniofacial dysmorphism, and increased apoptosis in sciatic nerve Schwann cells. The suckling defect was responsible for the death among lp(A1)((-/-)) neonates and the stunted growth of survivors. Impaired suckling behavior was attributable to defective olfaction, which is likely related to developmental abnormalities in olfactory bulb and/or cerebral cortex. Our results provide evidence that endogenous lysophospholipid signaling requires an lp receptor gene and indicate that LPA signaling through the LP(A1) receptor is required for normal development of an inborn, neonatal behavior.

Synthesis of ceramide analogues having the C(4)-C(5) bond of the long-chain base as part of an aromatic or heteroaromatic system

Two efficient and stereoselective methods are described for the preparation of aryl and heteroaryl ceramide analogues 2 and 3. The first route involves the addition of an aryllithium or a heteroaryllithium reagent (7a or 25a, respectively) to the L-serine-derived aldehyde 4, followed by hydrolysis of the oxazolidine, liberation of the amino group, and N-acylation. The second route, which was used to prepare arylceramide analogue 2 in eight steps and 28% overall yield starting with 3-bromobenzaldehyde, utilizes a Heck reaction to afford (E)-alpha,beta-unsaturated ester 16, then osmium-catalyzed asymmetric dihydroxylation for the introduction of the desired chirality at C-2 and C-3. Regioselective alpha-azidation of alpha-O-nosyl-beta-hydroxyester 18 with sodium azide, followed by LiAlH(4) reduction of the azido and ester groups and N-acylation, complete the synthesis of arylceramide analogue 2.

Glypican-4 is an FGF2-binding heparan sulfate proteoglycan expressed in neural precursor cells

FGF2 is a crucial mitogen for neural precursor cells in the developing cerebral cortex. Heparan sulfate proteoglycans (HSPGs) are thought to play a role in cortical neurogenesis by regulating the action of FGF2 on neural precursor cells. In this article, we present data indicating that glypican-4 (K-glypican), a GPI-anchored cell surface HSPG, is involved in these processes. In the developing mouse brain, glypican-4 mRNA is expressed predominantly in the ventricular zone of the telencephalon. Neither the outer layers of the telencephalic wall nor the ventricular zone of other parts of the developing brain express significant levels of glypican-4, with the exception of the ventricular zone of the tectum. In cultures of E13 rat cortical precursor cells, glypican-4 is expressed in cells immunoreactive for nestin and the D1.1 antigen, markers of neural precursor cells. Glypican-4 expression was not detected in early postmitotic or fully differentiated neurons. Recombinant glypican-4 produced in immortalized neural precursor cells binds FGF2 through its heparan sulfate chains and suppressed the mitogenic effect of FGF2 on E13 cortical precursor cells. The spatiotemporal expression pattern of glypican-4 in the developing cerebral wall significantly overlaps with that of FGF2. These results suggest that glypican-4 plays a critical role in the regulation of FGF2 action during cortical neurogenesis.

Functional comparisons of the lysophosphatidic acid receptors, LP(A1)/VZG-1/EDG-2, LP(A2)/EDG-4, and LP(A3)/EDG-7 in neuronal cell lines using a retrovirus expression system

Lysophosphatidic acid (LPA) is a potent lipid mediator with diverse physiological actions on a wide variety of cells and tissues. Three cognate G-protein-coupled receptors have been identified as mammalian LPA receptors: LP(A1)/VZG-1/EDG-2, LP(A2)/EDG-4, and LP(A3)/EDG-7. The mouse forms of these genes were analyzed in rodent cell lines derived from nervous system cells that can express these receptors functionally. An efficient retrovirus expression system was used, and each receptor was heterologously expressed in B103 rat neuroblastoma cells that neither express these receptors nor respond to LPA in all assays tested. Comparative analyses of signaling pathways that are activated within minutes of ligand delivery were carried out. LPA induced cell rounding in LP(A1)- and LP(A2)-expressing cells. By contrast, LP(A3) expression resulted in neurite elongation in B103 cells and inhibited LPA-dependent cell rounding in TR mouse neuroblast cells that endogenously express LP(A1) and LP(A2) but not LP(A3). Each of the receptors could couple to multiple G-proteins and induced LPA-dependent inositol phosphate production, mitogen-activated protein kinase activation, and arachidonic acid release while inhibiting forskolin-induced cAMP accumulation, although the efficacy and potency of LPA varied from receptor to receptor. These results indicate both shared and distinct functions among the three mammalian LPA receptors. The retroviruses developed in this study should provide tools for addressing these functions in vivo.

Use of a chiA probe for detection of chitinase genes in bacteria from the Chesapeake Bay(1)

PCR primers specific for the chiA gene were designed by alignment and selection of highly conserved regions of chiA sequences from Serratia marcescens, Alteromonas sp., Bacillus circulans and Aeromonas caviae. These primers were used to amplify a 225 bp fragment of the chiA gene from Vibrio harveyi to produce a chiA gene probe. The chiA PCR primers and probe were used to detect the presence of the chiA gene in an assemblage of 53 reference strains and gave consistent results. Selected chiA fragments amplified by PCR were cloned and sequenced from nine known strains and from Chesapeake Bay isolates 6d and 11d. This confirmed the specificity and utility of the primers for detection of chiA-positive environmental strains. Over 1000 bacterial isolates from Chesapeake Bay water samples were tested for the presence of the chiA gene which was found to be present in 5-41% (average 21%) of the culturable bacterial community. The approach developed in this study was valuable for isolation and enumeration of chiA-positive bacteria in environmental samples.

Transcriptional regulation of the adipocyte fatty acid synthase gene by agouti: interaction with insulin

Mice carrying dominant mutations at the agouti locus exhibit ectopic expression of agouti gene transcripts, obesity, and type II diabetes through unknown mechanisms. To gain insight into the role of agouti protein in modulating adiposity, we investigated regulation of a key lipogenic gene, fatty acid synthase (FAS) by agouti alone and in combination with insulin. Both agouti and insulin increase FAS activity in 3T3-L1 and in human adipocytes. Agouti and insulin independently and additively increase FAS activity in 3T3-L1 adipocytes. We further investigated the mechanism responsible for the agouti-induced FAS expression in these cells and demonstrated that both insulin (3-fold increase) and agouti (2-fold) increased FAS gene expression at the transcriptional level. Furthermore, insulin and agouti together exerted additive effects (5-fold increase) on FAS gene transcription. Transfection assays of FAS promoter-luciferase fusion gene constructs into 3T3-L1 adipocytes indicated that the agouti response element(s) is (are) located in the -435 to -415 region (-435/-415) of the FAS promoter. Nuclear proteins binding to this novel sequence are adipocyte specific. Thus the agouti response sequences mapped to a region upstream of the insulin-responsive element (which we previously reported to be located at -67/-52), consistent with additive effects of these two factors on FAS gene transcription.

Nocardiopsis kunsanensis sp. nov., a moderately halophilic actinomycete isolated from a saltern

A moderately halophilic actinomycete, designated HA-9T, was isolated from a saltern in Kunsan, Republic of Korea, and was the subject of polyphasic identification. Analysis of 16S rDNA indicated that the isolate belonged to the genus Nocardiopsis, but differed genetically from other Nocardiopsis species. Strain HA-9T contained meso-diaminopimelic acid, no diagnostic sugars, hexa- or octa-hydrogenated menaquinones with 10 isoprene units, straight-chain saturated or monounsaturated, iso-, anteiso-, 10-methyl branched fatty acids with 13-18 carbons and type III phospholipids. All of these characters consistently assign the isolate to the genus Nocardiopsis. All of the validly described Nocardiopsis species, including moderately halophilic Nocardiopsis halophila, can be differentiated from the saltern isolate using morphological and physiological traits. On the basis of polyphasic evidence, the name Nocardiopsis kunsanensis sp. nov. is proposed for strain HA-9T (= KCTC 9831T), which is designated the type strain.

Leuconostoc kimchii sp. nov., a new species from kimchi

A Gram-positive, catalase-negative, facultatively anaerobic, coccus-shaped bacterium, designated IH25T, was isolated from kimchi, a traditional Korean vegetable product. Phylogenetic analysis based on almost complete 16S rDNA sequences placed the isolate in a monophyletic clade corresponding to the genus Leuconostoc. All validly described species in the genus Leuconostoc, with the exception of Leuconostoc fallax, showed high sequence identity of over 97%. The 16S rDNA sequence of strain IH25T showed the highest homology to those of Leuconostoc gelidum DSM 5578T (98.9%) and Leuconostoc citreum KCTC 3526T (98.3 %). However, DNA-DNA hybridization experiments indicated that the organism represents a novel genomic species in the genus, since the previously known leuconostocs share DNA homology with strain IH25T of less than 70%. In this work, it is proposed that isolate IH25T be classified in the genus Leuconostoc as Leuconostoc kimchii sp. nov. The type strain of Leuconostoc kimchii is IH25T (= KCTC 2386T = IMSNU 11154T).

Phylogenetic analysis of Bacillus subtilis and related taxa based on partial gyrA gene sequences

Partial gyrA sequences were determined for twelve strains belonging to Bacillus amyloliquefaciens, B. atrophaeus, B. licheniformis, B. mojavensis, B. subtilis subsp. subtilis, B. subtilis subsp. spizizenii and B. vallismortis. The average nucleotide and translated amino acid similarities for the seven type strains were 83.7 and 95.1%, respectively, whereas the corresponding value for the 16S rRNA sequences was 99.1%. All of the type strains were sharply separated; the closest relationship was found between B. atrophaeus and B. mojavensis which shared a nucleotide similarity of 95.8%. Phylogenetic trees were inferred from gyrA nucleotide sequences using the neighbor-joining, Fitch-Margoliash and maximum parsimony algorithms. The test strains were divided into four groups, which generally reflected results previously reported in restriction digest and DNA-DNA hybridization studies. It is concluded from the comparative sequence analysis that the gyrA sequences provide a firm framework for the rapid and accurate classification and identification of Bacillus subtilis and related taxa.

Mechanism-based inactivation of cytochromes P450 2B1 and P450 2B6 by 2-phenyl-2-(1-piperidinyl)propane

2-Phenyl-2-(1-piperidinyl)propane (PPP), an analog of phencyclidine, was tested for its ability to inactivate cytochrome P450s (P450s) 2B1 and 2B6. PPP inactivated the 7-(benzyloxy)resorufin O-dealkylation activity of liver microsomes obtained from phenobarbital-induced rats with a K(I) of 11 microM. The 7-ethoxy-4-(trifluoromethyl)coumarin O-deethylation activity of purified rat liver P450 2B1 and expressed human P450 2B6 was inactivated by PPP in a reconstituted system containing NADPH-cytochrome P450 reductase and lipid. In the presence of NADPH, the loss of activity was time- and concentration-dependent, and followed pseudo first order kinetics. The rate of inactivation for P450 2B1 was 0.3 min(-1), and the concentration of PPP required to achieve half-maximal inactivation was 12 microM. The time for 50% of the P450 2B1 to become inactivated at saturating concentrations of PPP was 2.5 min. P450 2B6 was inactivated with a k(inact) of 0.07 min(-1), a K(I) of 1.2 microM, and a t(1/2) of 9.5 min. The inactivated P450s 2B1 and 2B6 lost about 25 and 15%, respectively, of their ability to form a CO-reduced complex, suggesting that the loss of activity was caused by a PPP modification of the apoprotein rather than the heme. The estimated partition ratio for P450s 2B1 and 2B6 with PPP was 31 and 15, respectively. The inactivation was not reversible and reductase activity was not affected. Coincubation of P450 2B1 and 2B6 with PPP and NADPH in the presence of an alternate substrate protected both enzymes from inactivation. The exogenous nucleophile GSH did not affect the rate of inactivation. PPP-inactivated P450s 2B1 and 2B6 were recognized on Western blots by an antibody generated to phencyclidine that had been conjugated to BSA. Stoichiometries of 1.4:1 and 0.7:1 were determined for the binding of a [3H]PPP metabolite to P450 2B1 and 2B6, respectively.

Decreased apoptosis in proliferative and postmitotic regions of the Caspase 3-deficient embryonic central nervous system

Caspase 3 (CPP32/Yama/apopain), a mammalian homolog of the Caenorhabditis elegans pro-cell death gene ced-3, is required for normal programmed cell death (PCD) in the nematode. Its prior deletion by homologous recombination in mice resulted in embryonic/early postnatal lethality associated with dramatic central nervous system (CNS) hyperplasia, yet a reported subtle decrease in cell death (Kuida et al. [1996] Nature 384:368-372). By comparison, the magnitude and distribution of dying cells identified using a DNA end-labeling technique, in situ end-labeling plus (ISEL+) (Blaschke et al. [1996] Development 122:1165-1174; Blaschke et al. [1998] J. Comp. Neurol. 396:39-50), supported an alternative explanation where the loss of caspase 3 function produces a more pervasive block in cell death, particularly among neuroblasts. To determine the relationship between loss of caspase 3 and dying cells identified by ISEL+, we analyzed caspase 3 +/+, +/-, and -/- embryos for normal caspase 3 expression and ISEL+ labeling. Both caspase 3 mRNA and active caspase 3 protein are present throughout the +/+ embryonic CNS, and both are absent from -/- embryonic cortices. Quantitation of dying cells identified by ISEL+ reveals a 30% reduction of labeled cells throughout the caspase 3 -/- embryonic cortices relative to +/+ littermates. Associated with this decrease is marked expansion of the total population of actively proliferating neuroblasts identified by 5-bromo-2;-deoxyuridine incorporation that nevertheless appears to maintain histological features of normal neurogenesis rather than dysregulated, neoplastic growth. These data indicate that caspase 3 deficiency results in a pervasive, albeit partial, decrease in embryonic neuroblast apoptosis that can account for the observed phenotypic hyperplasia in -/- embryos, and support the additional operation of caspase 3-independent PCD mechanisms during embryonic CNS development.

Polyphasic assignment of an aromatic-degrading Pseudomonas sp., strain DJ77, in the genus Sphingomonas as Sphingomonas chungbukensis sp. nov

Pseudomonas sp. strain DJ77, which was described as an aromatic-degrading bacterium, was investigated to clarify its taxonomic position. Phylogenetic analysis based on 16S rDNA sequences indicated that the strain belonged to the genus Sphingomonas and formed a monophyletic clade with the type strains of Sphingomonas chlorophenolica, Sphingomonas herbicidovorans and Sphingomonas yanoikuyae with sequence similarity values of 98.1, 96.1 and 95.6%, respectively. Genomic relatedness based on DNA-DNA hybridization of strain DJ77 to these strains is 7-14%. Strain DJ77 contained ubiquinone 10 as the main respiratory quinone, and the G+C content of DNA was 63 mol%. The organism contained octadecenoic acid (67%) as major cellular fatty acid. Strain DJ77 can be readily differentiated from representative members of the genus Sphingomonas using a battery of biochemical tests. On the basis of polyphasic evidence, it is proposed that strain DJ77, previously known as Pseudomonas sp., be reclassified in the genus Sphingomonas as Sphingomonas chungbukensis sp. nov. The type strain is strain DJ77T (= KCTC 2955T = IMSNU 11152T).

Paenibacillus koreensis sp. nov., a new species that produces an iturin-like antifungal compound

A bacterial strain, YC300T, that produces an iturin-like antifungal antibiotic was isolated from compost and identified as member of the genus Paenibacillus. Gram reaction of the strain was variable depending upon growth stages and culture media. Three different types of colonies were developed on tryptic soy agar. The organism was facultatively anaerobic and grew at 50 degrees C. The DNA G+C content was 54 mol % and anteiso-C15:0 was the major fatty acid. A 0.9 kb fragment was produced by PCR amplification of strain YC300T DNA using primers PAEN515F and 1377R. Levels of 16S rDNA similarity between strain YC300T and other Paenibacillus species were between 89.8 and 94.8%. Phylogenetically, strain YC300T formed a significant monophyletic clade with Paenibacillus validus. It is clear from polyphasic evidence that the isolate should be classified as Paenibacillus koreensis sp. nov., the type strain of which is YC300T (= KCTC 2393T, KCCM 40903T).

Systematic analysis of xanthomonads (Xanthomonas spp.) associated with pepper and tomato lesions

The taxonomy and evolutionary relationships among members of the genus Xanthomonas associated with tomato and pepper have been a matter of considerable controversy since their original description in 1921. These bacteria, which are a major affliction of tomato and pepper crops in warm and humid regions, were originally described as a single species, but subsequent research has shown the existence of at least two genetic groups differentiated by physiological, biochemical and pathological characteristics. This work synthesizes the findings from several approaches, including pathogenicity tests, enzymic activity, restriction fragment analysis of the entire genome, DNA-DNA hybridization and RNA sequence comparisons based on a 2097 base sequence comprising the 16S rRNA gene, the intergenic spacer located between the 16S and 23S rRNA genes and a small region of the 23S rRNA gene. Within the group of xanthomonads pathogenic on pepper and tomato four distinct phenotypic groups exist, of which three form distinct genomic species. These include Xanthomonas axonopodis pv. vesicatoria (A and C group), Xanthomonas vesicatoria (B group) and Xanthomonas gardneri (D group). On the basis of phenotypic and genotypic differences between A- and C-group strains, the C strains should be considered as a subspecies within Xanthomonas axonopodis pv. vesicatoria.

Neurobiology of receptor-mediated lysophospholipid signaling. From the first lysophospholipid receptor to roles in nervous system function and development

Identification of the first lysophospholipid receptor, LPA1/Vzg-1, cloned by way of neurobiological analyses on the embryonic cerebral cortex, has led to the realization and demonstration that there exist multiple, homologous LP receptors, including those encoded by a number of orphan receptor genes known as "Edg," all of which are members of the G-protein-coupled receptor (GPCR) superfamily. These receptors interact with apparent high affinity for lysophosphatidic acid (LPA) or sphingosine-1-phosphate (S1P or SPP), and are referred to based upon their functional identity as lysophospholipid receptors: LPA and LPB receptors, respectively, with the expectation that additional subgroups will be identified (i.e., LPC, etc.). Here an update is provided on insights gained from analyses of these receptor genes as they relate to the nervous system, particularly the cerebral cortex, and myelinating cells (oligodendrocytes and Schwann cells).

Defective embryonic neurogenesis in Ku-deficient but not DNA-dependent protein kinase catalytic subunit-deficient mice

Mammalian nonhomologous DNA end joining employs Ku70, Ku80, DNA-dependent protein kinase catalytic subunit (DNA-PKcs), XRCC4, and DNA ligase IV (Lig4). Herein, we show that Ku70 and Ku80 deficiency but not DNA-PKcs deficiency results in dramatically increased death of developing embryonic neurons in mice. The Ku-deficient phenotype is qualitatively similar to, but less severe than, that associated with XRCC4 and Lig4 deficiency. The lack of a neuronal death phenotype in DNA-PKcs-deficient embryos and the milder phenotype of Ku-deficient versus XRCC4- or Lig4-deficient embryos correlate with relative leakiness of residual end joining in these mutant backgrounds as assayed by a V(D)J recombination end joining assay. We conclude that normal development of the nervous system depends on the four evolutionarily conserved nonhomologous DNA end joining factors.

Idiomarina gen. nov., comprising novel indigenous deep-sea bacteria from the Pacific Ocean, including descriptions of two species, Idiomarina abyssalis sp. nov. and Idiomarina zobellii sp. nov

Two bacterial strains, KMM 227T and 231T, were isolated from seawater samples collected from the north-western Pacific Ocean at a depth of 4000-5000 m and were characterized using polyphasic taxonomy. Both were Gram-negative, psychrotolerant, heterotrophic, aerobic and required NaCl for growth (0.6-15.0%). The temperature for growth was 4-30 degrees C. Both strains were rod-shaped, with a single flagellum. However, strain KMM 231T revealed a single long fimbrium. Cellular fatty acids detected in the isolates were predominantly odd-numbered and iso-branched, with 15 and 17 carbons (ca. 70%). Also present were saturated and monounsaturated straight-chain fatty acids. Results of phylogenetic analyses, employing three tree-making methods, strongly indicated that the two strains formed a distinct lineage within a clade containing the genera Alteromonas, Colwellia and Pseudoalteromonas, in the gamma-Proteobacteria. The two strains shared 16S rDNA sequence similarity of 96.9% and genomic DNA relatedness of 27%; the latter was determined by dot-blot hybridization. The strains were differentiated by the presence of fimbria, production of chitinase, ability to grow on 15% NaCl and BIOLOG profiles. Given the polyphasic evidence accumulated in this study, it is proposed that the two deep-sea isolates be classified in the genus Idiomarina gen. nov., as Idiomarina abyssalis sp. nov. (type strain is KMM 227T) and Idiomarina zobellii sp. nov. (type strain is KMM 231T).

Genomic characterization of the lysophosphatidic acid receptor gene, lp(A2)/Edg4, and identification of a frameshift mutation in a previously characterized cDNA

To understand the regulation, evolution, and genetics of lp(A2)/Edg4, a second lysophosphatidic acid receptor gene, we characterized its complete cDNA sequence, genomic structure, and chromosomal location. The full-length mouse transcript sequence was determined using rapid amplification of cDNA ends. Southern blot and restriction fragment length polymorphism segregation analyses revealed that the mouse gene was present as a single copy and located at the middle of Chromosome 8 near the mutations for myodystrophy (myd) and "kidney-anemia-testes" (kat). This region is syntenic with human chromosome 19p12, where the human genomic clone containing the lp(A2) gene (EDG4) was mapped. Sequence analysis of genomic clones demonstrated that both mouse and human transcripts were encoded by three exons, with an intron separating the coding region for transmembrane domain VI. Reverse transcriptase-PCR demonstrated that the three exons were spliced in all mouse tissues shown to express the transcript. Finally, in a comparison of all human lp(A2) sequences present in the database, we identified several sequence variants in multiple tumors. One such variant (a G deletion) in the initially characterized Edg4 cDNA clone (derived from an ovarian tumor) results in a frameshift mutation near the 3' end of the coding region. In addition to increasing our understanding of the mechanisms underlying lysophosphatidic acid signaling and lysophospholipid receptor gene evolution, these results have important implications regarding the genomic targeting and oncogenic potential of lp(A2).

Two-dimensional gel analysis of haemolymph proteins from Plasmodium-melanizing and -non-melanizing strains of Anopheles gambiae

Haemolymph polypeptides from Plasmodium-refractory and -susceptible mosquitoes were compared by one- and two-dimensional gel electrophoresis. The refractory strain of Anopheles gambiae kills malaria parasites by a humoral melanization mechanism whereas the parasites develop normally in susceptible mosquitoes. The two strains respond in a similar manner to carboxy-methyl-Sephadex beads that have been injected into the thoracic haemocoel, i.e. beads are strongly melanized in refractory but not susceptible mosquitoes. Protein profiles were compared between strains following cold shock (naïve control), saline injection and Sephadex bead injection. Using the susceptible naïve control as the standard, eight constitutively expressed polypeptides were specific to naïve susceptible mosquitoes while twelve other spots were reduced, enhanced or specific to refractory mosquitoes. Several of the strain-specific spots probably comprise related pairs (one in each strain) which vary only in isoelectric focusing point. Nine spots were induced by sham injection or by an injection of beads or saline, but none was reproducibly different between the strains. Amino acid sequence analysis of one of the refractory strain-specific spots identified it as AgSp14D1, an A. gambiae infection-responsive serine protease that is most similar to the Drosophila gene easter and Manduca prophenoloxidase activating enzyme. This gene maps to polytene chromosome division 14, which has been implicated in the melanization phenotype by quantitative trait loci mapping.

Akt protein kinase inhibits Rac1-GTP binding through phosphorylation at serine 71 of Rac1

A putative Akt kinase phosphorylation site ((64)ydRIRplSYp(73)) was found in Rac1/CDC42 and Rho family proteins (RhoA, RhoB, RhoC, and RhoG). Phosphorylation of Rac1 by Akt kinase was assayed with recombinant Rac1 protein and the fluorescein-labeled Rac1 peptide. It was shown that the Rac1 peptide and the recombinant protein were phosphorylated by the activated recombinant Akt kinase and the lysate of SK-MEL28 cells, a human melanoma cell line. The phosphorylation of Rac1 inhibited its GTP-binding activity without any significant change in GTPase activity. Both the GTP-binding and GTPase activities of Rac1 S71A protein (with the serine residue to be phosphorylated replaced with alanine) were abolished regardless of the treatment of Akt kinase. Akt kinase activity and Rac1 peptide phosphorylation were down-regulated by the treatment of SK-MEL28 cells with wortmannin or LY294002 (a phosphoinositide 3-kinase inhibitor), but JNK/SAPK kinase activity was up-regulated. Thus, the results suggest that Akt kinase of the phosphoinositide 3-kinase signal transduction pathway phosphorylates serine 71 of Rac1 as one of its authentic substrates and modulates the Rac1 signal transduction pathway through phosphorylation.

Reclassification of Alteromonas distincta Romanenko et al. 1995 as Pseudoalteromonas distincta comb. nov

The 16S rRNA gene of Alteromonas distincta KMM 638T was amplified, cloned and sequenced. The nucleotide sequence was aligned with sequences of representative strains of Alteromonas, Moritella, Pseudoalteromonas and Shewanella. Results of phylogenetic analysis, using neighbour-joining and Fitch-Margoliash methods, clearly indicated that this species should be assigned to the genus Pseudoalteromonas. On the basis of polyphasic data obtained from previous work and this study, it is proposed that the species Alteromonas distincta be reclassified as Pseudoalteromonas distincta comb. nov. with type strain KMM 638T (= ATCC 700518T).

A proposal for the reclassification of Bdellovibrio stolpii and Bdellovibrio starrii into a new genus, Bacteriovorax gen. nov. as Bacteriovorax stolpii comb. nov. and Bacteriovorax starrii comb. nov., respectively

Bdellovibrios are unique bacteria with the ability to prey upon a wide variety of susceptible Gram-negative bacteria. Micro-organisms exhibiting this trait have been included in the genus Bdellovibrio despite their isolation from diverse habitats and relatively unstudied taxonomic relatedness. In this study, 16S rDNA sequences were compared from known terrestrial Bdellovibrio species, Bdellovibrio bacteriovorus 100T, Bdellovibrio stolpii Uki2T and Bdellovibrio starrii A3.12T in order to study their phylogenetic relationship. The two sequences from B. stolpii Uki2T and B. starrii A3.12T were 90.0% similar to each other but exhibited only 81.7% and 81.2% similarity, respectively to B. bacteriovorus 100T. Phylogenetic analysis indicated that B. bacteriovorus 100T clustered in a separate clade from B. starrii A3.12T and B. stolpii Uki2T, demonstrating only a distant relationship between B. bacteriovorus 100T and the other two recognized type species. DNA-DNA hybridization experiments also demonstrated <4% hybridization between these three species. On the basis of the results obtained from the phylogenetic analysis and DNA-DNA hybridization studies, it is proposed that B. stolpii Uki2T and B. starrii A3.12T should be transferred to a new genus, Bacteriovorax gen. nov. as Bacteriovorax stolpii comb. nov. and Bacteriovorax starrii comb. nov., respectively. It is also proposed that the type species for the new genus Bacteriovorax should be Bacteriovorax stolpii comb. nov.

Lysophospholipid receptors: implications for neural signaling

Lysophospholipids (LPs) such as lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) represent quantitatively minor phospholipid species that nonetheless are capable of acting as extracellular signals. As an organ system dominated by lipids, the nervous system would seem a likely benefactor of this form of intercellular signaling. A major difficulty in determining the neurobiological importance of these lipids, however, has been a lack of cloned receptors. The unavailability, indeed, uncertain existence, of these receptors has been particularly problematic because of the absence of specific, competitive antagonists to block function. Further, these lipids have detergent-like chemical structures, raising the explanation that any observed effects of exogenously applied lysophospholipids could be due to nonspecific membrane perturbations. During studies of G-protein coupled receptor (GPCR) genes involved with cerebral cortical neurogenesis, the first lysophospholipid receptor gene (lpA1/vzg-1) was isolated (Hecht et al., J. Cell Biol., 135, 1071, 1996), implicating receptor-mediated lysophospholipid signaling as potentially important components of nervous system development and function. Expression studies indicated roles in neurogenesis, cortical development, and effects on glia, particularly oligodendrocyte and Schwann cell development. Reviewed here are the molecular biology of LP receptors, relevant aspects of intracellular signaling, and their possible roles in the nervous system.

Amycolatopsis thermoflava sp. nov., a novel soil actinomycete from Hainan Island, China

A soil isolate, which had been assigned to the genus Nocardia, was shown to have properties consistent with its classification in the genus Amycolatopsis. An almost complete nucleotide sequence of the 16S rDNA of the strain was determined following cloning and sequencing of the amplified gene. The sequence was aligned with those available for members of the family Pseudonocardiaceae and related taxa and phylogenetic trees were inferred using three tree-making algorithms. The organism consistently formed a distinct monophyletic clade with the type strain of Amycolatopsis methanolica, but DNA-DNA relatedness data showed that the two strains belonged to distinct genomic species. The organism was also distinguished from the type strains of all validly described species of Amycolatopsis using a battery of phenotypic properties. The genotypic and phenotypic data show that the strain merits recognition as a new species of the genus Amycolatopsis. The name proposed for the new species is Amycolatopsis thermoflava sp. nov. The type strain is IFO 14333T.

Induction of mosquito hemolymph proteins in response to immune challenge and wounding

The rapid induction of proteins in the hemolymph of the mosquito, Anopheles gambiae, was examined after wounding or injection of immune elicitors (Escherichia coli, lipopolysaccharide, laminarin, zymosan). One-dimensional gel electrophoresis revealed at least six hemolymph polypeptides >25 kDa that consistently appeared after any breech of the cuticle. All of these polypeptides appeared in the hemolymph within 30 min and reached a maximum concentration after approx. 6 h. No proteins were specifically induced by bacteria or bacterial or fungal cell wall products, however two constitutively expressed proteins were repressed by these injections. Patterns of hemolymph proteins were further analyzed by two-dimensional electrophoresis. Seven spots were enhanced or induced 2 h after injection in four replicate experiments. An additional two spots demonstrated some variability between replicates, but were generally responsive to injection. These rapidly induced polypeptides are candidates for regulating and initiating the mosquito's responses to pathogens and wounding.

Ethmoidal dural arteriovenous fistulae: an assessment of surgical and endovascular management

OBJECTIVE

Endovascular treatment of ethmoidal dural arteriovenous fistulae (DAVFs) has become technically feasible, but its relative risks and benefits have not justified its use. We present a series of patients with ethmoidal DAVFs treated almost exclusively with surgery at an institution where expert endovascular therapy was available. Surgical risks, treatment efficacy, and patient outcomes were determined for comparison with published endovascular data.

METHODS

Sixteen patients with ethmoidal DAVFs were treated during a 17-year period from 1982 to 1999. In three patients, feeding arteries from the internal maxillary artery were embolized; no ophthalmic artery embolizations were performed. A low bifrontal surgical approach was used in most patients to expose, coagulate, and divide the fistulous site.

RESULTS

Ethmoidal DAVFs were occluded grossly and angiographically in all 16 patients. There was no treatment-associated neurological morbidity, and clinical outcomes were good in all but one patient who was comatose initially.

CONCLUSION

Review of our surgical experience with ethmoidal DAVFs as well as published endovascular results for these lesions suggests that endovascular management of ethmoidal DAVFs has a small but clinically significant risk to vision, is rarely effective in curing the fistula, and does not eliminate the need for surgery. In contrast, surgical management has no associated risk to vision, is highly effective at obliterating the fistula, and can contribute to good clinical outcomes in most patients. For these reasons, surgical management of ethmoidal DAVFs remains the treatment of choice.

Developmental neurobiology: a genetic Cheshire cat?

In the wake of evidence that essential neurogenic processes might involve aspects of DNA rearrangement, recent discoveries about the unusual arrangement of genes encoding neuronal adhesion molecules known as protocadherins are very intriguing. But is this just a coincidence?

Nocardia uniformis nom. rev

A soil isolate representing the putatively novel species 'Nocardia uniformis' was found to have morphological, staining and chemotaxonomic properties consistent with its classification in the genus Nocardia. An almost complete sequence of the 16S rDNA of the strain was determined following cloning and sequencing of the amplified gene. The sequence was aligned with those available for nocardiae and phylogenetic trees were inferred using four tree-making algorithms. The organism was consistently associated with the type strain of Nocardia otitidiscaviarum albeit with a relatively low bootstrap value recorded for neighbour-joining analysis. The strain was also readily separated from representatives of all validly described Nocardia species using a set of phenotypic properties. The genotypic and phenotypic data indicate that the strain should be assigned to the genus Nocardia as a new species. The name proposed for the new species is Nocardia uniformis. The type strain is JCM 3224T.

A growing family of receptor genes for lysophosphatidic acid (LPA) and other lysophospholipids (LPs)

A missing component in the experimental analysis of cell signaling by extracellular lysophospholipids such as lysophosphatidic acid (LPA) or sphingosine-1-phosphate (S1P) has been cloned receptors. Through studies on the developing brain, the first such receptor gene (referred to as vzg-1) was identified, representing a member of the G-protein coupled receptor (GPCR) super family (1). Here we review the neurobiological approach that led to both its cloning and identification as a receptor for LPA, along with related expression data. Summarized sequence and genomic structure analyses indicate that this first, functionally identified receptor is encoded by a member of a growing gene family that divides into at least two subgroups: genes most homologous to the high-affinity LPA receptor encoded by vzg-1, and those more homologous to an orphan receptor gene edg-1 that has recently been identified as a S1P receptor. A provisional nomenclature is proposed, based on published functional ligand actions, amino acid composition and genomic structure whereby the receptors encoded by these genes are referred to as lysophospholipid (LP) receptors, with subgroups distinguished by letter and number subscripts (e.g., LPA1 for Vzg-1, and LPB1 for Edg-1). Presented expression data support the recently published work indicating that members of the LPB1 subgroup are receptors for the structurally-related molecule, S1P. The availability of cloned LP receptors will enhance the analysis of the many documented LP effects, while their prominent expression in the nervous system indicates significant but as yet unknown roles in development, normal function, and neuropathology.

Novel dendritic kinesin sorting identified by different process targeting of two related kinesins: KIF21A and KIF21B

Neurons use kinesin and dynein microtubule-dependent motor proteins to transport essential cellular components along axonal and dendritic microtubules. In a search for new kinesin-like proteins, we identified two neuronally enriched mouse kinesins that provide insight into a unique intracellular kinesin targeting mechanism in neurons. KIF21A and KIF21B share colinear amino acid similarity to each other, but not to any previously identified kinesins outside of the motor domain. Each protein also contains a domain of seven WD-40 repeats, which may be involved in binding to cargoes. Despite the amino acid sequence similarity between KIF21A and KIF21B, these proteins localize differently to dendrites and axons. KIF21A protein is localized throughout neurons, while KIF21B protein is highly enriched in dendrites. The plus end-directed motor activity of KIF21B and its enrichment in dendrites indicate that models suggesting that minus end-directed motor activity is sufficient for dendrite specific motor localization are inadequate. We suggest that a novel kinesin sorting mechanism is used by neurons to localize KIF21B protein to dendrites since its mRNA is restricted to the cell body.

Analysis of 16S-23S rRNA intergenic spacer regions of Vibrio cholerae and Vibrio mimicus

Vibrio cholerae identification based on molecular sequence data has been hampered by a lack of sequence variation from the closely related Vibrio mimicus. The two species share many genes coding for proteins, such as ctxAB, and show almost identical 16S DNA coding for rRNA (rDNA) sequences. Primers targeting conserved sequences flanking the 3' end of the 16S and the 5' end of the 23S rDNAs were used to amplify the 16S-23S rRNA intergenic spacer regions of V. cholerae and V. mimicus. Two major (ca. 580 and 500 bp) and one minor (ca. 750 bp) amplicons were consistently generated for both species, and their sequences were determined. The largest fragment contains three tRNA genes (tDNAs) coding for tRNAGlu, tRNALys, and tRNAVal, which has not previously been found in bacteria examined to date. The 580-bp amplicon contained tDNAIle and tDNAAla, whereas the 500-bp fragment had single tDNA coding either tRNAGlu or tRNAAla. Little variation, i.e., 0 to 0.4%, was found among V. cholerae O1 classical, O1 El Tor, and O139 epidemic strains. Slightly more variation was found against the non-O1/non-O139 serotypes (ca. 1% difference) and V. mimicus (2 to 3% difference). A pair of oligonucleotide primers were designed, based on the region differentiating all of V. cholerae strains from V. mimicus. The PCR system developed was subsequently evaluated by using representatives of V. cholerae from environmental and clinical sources, and of other taxa, including V. mimicus. This study provides the first molecular tool for identifying the species V. cholerae.

Schwann cell survival mediated by the signaling phospholipid lysophosphatidic acid

Lysophosphatidic acid (LPA) is a bioactive phospholipid with properties of an extracellular growth factor for many cell lines, including those derived from neuroblastomas. However, the relevance of LPA signaling to the normal, developing nervous system is unknown, in part reflecting the previous unavailability of cloned receptor genes. Recent studies of the first such gene, encoding the G protein-coupled receptor LPA1/VZG-1 (lysophospholipid receptor A1/ventricular zone gene-1), revealed a major locus of expression in oligodendrocytes and Schwann cells (SCs) during development, suggesting an influence of LPA on these myelinating cells. Here we report that LPA (>/=10 nM) is a potent survival factor for cultured neonatal SCs, with survival activity equaling the maximal effect of neuregulin, the major peptide SC survival factor. LPA activates a pharmacologically defined signaling pathway in SCs, involving Gi and phosphoinositide 3-kinase. Moreover, LPA's effect depends on Akt, a downstream kinase that can mediate phosphoinositide 3-kinase-dependent survival, as demonstrated by both Western blot and transfection analyses. Overexpression of functional epitope-tagged LPA1/VZG-1 protein decreases SC apoptosis in response to serum withdrawal. These data demonstrate a role for extracellular LPA and its receptor LPA1/VZG-1 in SC survival and, more broadly, implicate G protein-coupled receptor-mediated lysophospholipid signaling as a significant mechanism in neural development.

Developmental neurobiology: Alternative ends for a familiar story?

Somatic DNA recombination is essential for production of functional antigen receptor genes of T and B lymphocytes, but it is thought to be unique to the immune system. Recent studies have now shown that recombination-related genes are also necessary for normal neuronal development.

Kitasatospora cheerisanensis sp. nov., a new species of the genus Kitasatospora that produces an antifungal agent

An actinomycete, strain YC75T, which produced bafilomycin-like antifungal compounds, was identified as a member of the genus Kitasatospora on the basis of morphological and chemotaxonomic characteristics. The strain produced the aerial and fragmenting vegetative mycelia consisting of straight chains of 20 or more smooth-surfaced spores. Submerged spores were formed in tryptic soy broth. No soluble pigments were formed. Whole-cell hydrolysates contained glucose and mannose, but not galactose. The 16S rDNA sequence of YC75T was compared with those of the other representative kitasatosporae and streptomycetes. Strain YC75T formed a significant monophyletic clade with Kitasatospora phosalacinea. The levels of DNA relatedness between strain YC75T and representatives of the genus Kitasatospora ranged from 16 to 59% including K. phosalacinea (28 and 40%). It is clear from polyphasic evidence that the isolate should be classified as Kitasatospora cheerisanensis sp. nov., whose type strain is YC75T (= KCTC 2395T). The presence of galactose in whole-cell hydrolysates may not be a stable chemical marker for the genus Kitasatospora.

Nocardia salmonicida nom. rev., a fish pathogen

An almost complete gene sequence of 16S rDNA of 'Nocardia salmonicida' strain JCM 4826T was determined following cloning and sequencing of the amplified gene. The sequence was aligned with those available for nocardiae and phylogenetic trees inferred using four tree-making algorithms. The organism and the type strain of Nocardia asteroides consistently formed a monophyletic clade with a distant sequence similarity of 97%. However, previous DNA relatedness experiments showed that strain JCM 4826T and Nocardia asteroides ATCC 19247T belong to different genomic species. The organism was also distinguished from representatives of all validly described species of Nocardia using a combination of phenotypic features. The polyphasic evidence showed that the strain merits recognition as a new species of the genus Nocardia. The name proposed for the new species is Nocardia salmonicida nom. rev.

Lysophosphatidic acid stimulates neurotransmitter-like conductance changes that precede GABA and L-glutamate in early, presumptive cortical neuroblasts

During neurogenesis in the embryonic cerebral cortex, the classical neurotransmitters GABA and L-glutamate stimulate ionic conductance changes in ventricular zone (VZ) neuroblasts. Lysophosphatidic acid (LPA) is a bioactive phospholipid producing myriad effects on cells including alterations in membrane conductances (for review, see Moolenaar et al., 1995). Developmental expression patterns of its first cloned receptor gene, lpA1/vzg-1 (Hecht et al., 1996; Fukushima et al., 1998) in the VZ suggested that functional LPA receptors were synthesized at these early times, and thus, LPA could be an earlier stimulus to VZ cells than the neurotransmitters GABA and L-glutamate. To address this possibility, primary cultures of electrically coupled, presumptive cortical neuroblast clusters were identified by age, morphology, electrophysiological profile, BrdU incorporation, and nestin immunostaining. Single cells from cortical neuroblast cell lines were also examined. Whole-cell variation of the patch-clamp technique was used to record from nestin-immunoreactive cells after stimulation by local administration of ligands. After initial plating at embryonic day 11 (E11), cells responded only to LPA but not to GABA or L-glutamate. Continued growth in culture for up to 12 hr produced more LPA-responsive cells, but also a growing population of GABA- or L-glutamate-responsive cells. Cultures from E12 embryos showed LPA as well as GABA and L-glutamate responses, with LPA-responsive cells still representing a majority. Overall, >50% of cells responded to LPA with depolarization mediated by either chloride or nonselective cation conductances. These data implicate LPA as the earliest reported extracellular stimulus of ionic conductance changes for cortical neuroblasts and provide evidence for LPA as a novel, physiological component in CNS development.

Comparative analysis of three murine G-protein coupled receptors activated by sphingosine-1-phosphate

The cloning and analysis of the first identified lysophosphatidic acid (LPA) receptor gene, lpA1 (also referred to as vzg-1 or edg-2), led us to identify homologous murine genes that might also encode receptors for related lysophospholipid ligands. Three murine genomic clones (designated lpB1, lpB2, and lpB3) were isolated, corresponding to human/rat Edg-1, rat H218/AGR16, and human edg-3, respectively. Based on the amino acid similarities of their predicted proteins (44-52% identical), the three lpB genes could be grouped into a separate G-protein coupled receptor subfamily, distinct from that containing the LPA receptor genes lpA1 and lpA2. Unlike lpA1 and lpA2, which contain multiple coding exons, all lpB members contained a single coding exon. Heterologous expression of individual lpB members in a hepatoma cell line (RH7777), followed by 35S-GTPgammaS incorporation assays demonstrated that each of the three LPB receptors conferred sphingosine-1-phosphate-dependent, but not lysophosphatidic acid-dependent, G-protein activation. Northern blot and in situ hybridization analyses revealed overlapping as well as distinct expression patterns in both embryonic and adult tissues. This comparative characterization of multiple sphingosine-1-phosphate receptor genes and their spatiotemporal expression patterns will aid in understanding the biological roles of this enlarging lysophospholipid receptor family.

Expanded polyglutamine domain proteins bind neurofilament and alter the neurofilament network

Eight inherited neurodegenerative diseases are caused by genes with expanded CAG repeats coding for polyglutamine domains in the disease-producing proteins. The mechanism by which this expanded polyglutamine domain causes neurodegenerative disease is unknown, but nuclear and cytoplasmic polyglutamine protein aggregation is a common feature. In transfected COS7 cells, expanded polyglutamine proteins aggregate and disrupt the vimentin intermediate filament network. Since neurons have an intermediate filament network composed of neurofilament (NF) and NF abnormalities occur in neurodegenerative diseases, we examined whether pathologic-length polyglutamine domain proteins also interact with NF. We expressed varying lengths polyglutamine-green fluorescent protein fusion proteins in a neuroblast cell line, TR1. Pathologic-length polyglutamine-GFP fusion proteins formed large cytoplasmic aggregates surrounded by neurofilament. Immunoisolation of pathologic-length polyglutamine proteins coisolated 68-kDa NF protein demonstrating molecular interaction. These observations suggest that polyglutamine interaction with NF is important in the pathogenesis of the polyglutamine repeat diseases.