Nocardia flavorosea sp. nov

An actinomycete strain, 'Nocardai flavorosea' JCM 3332, was found to have properties consistent with its classification in the genus Nocardia. An almost complete gene 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 organisms consistently formed a distinct clade with the type strain of Nocardia carnea. However, DNA relatedness experiments showed that the strain and N. carnea DSM 43397T belonged to two distinct genomic species. The organism was also distinguished from representative of all of the validly described species of Nocardia using a combination of phenotypic properties. These genotypic and phenotypic data show that the strain merits recognition as a new species of the genus Nocardia. The name proposed for the new species of is Nocardia flavorosea sp. nov. The type strain is JCM 3332T.

Rhodococcal systematics: problems and developments

Various approaches that have been used in the development of a system of classification for the genus Rhodococcus are discussed. The application of chemotaxonomic, molecular systematic and numerical phenetic methods have greatly contributed to improvements in the systematics of rhodococci and related mycolic-acid containing actinomycetes. The genus currently encompasses twelve validly described species but improved diagnostic methods are needed to distinguish between them. In addition, evidence from 16S ribosomal RNA sequencing suggests that the genus is still heterogeneous.

Programmed cell death is a universal feature of embryonic and postnatal neuroproliferative regions throughout the central nervous system

During central nervous system (CNS) development, programmed cell death (PCD) has been viewed traditionally as a fate reserved for differentiating neurons that are in the process of making synaptic connections. Recent studies in the embryonic cerebral cortex (Blaschke et al. [1996] Development 122:1165-1174), however, have shown that many neuroblasts in the proliferative ventricular zone undergo PCD as well and that this likely represents a novel form distinct from that found in regions of postmitotic neurons. To determine the commonality of this form of PCD throughout the CNS, the prevalence of dying cells identified by in situ end labeling plus (ISEL +; Blaschke et al. [1996]) was determined within populations of proliferating neuroblasts that were identified by rapid bromodeoxyuridine incorporation. Based on this approach, dying cells were observed to be a common feature of all proliferative neuroblast populations examined. In addition, when ISEL+ was combined with in situ hybridization for postmitotic neural gene-1 (png-1; Weiner and Chun [1997] J. Comp. Neurol. 381:130-142), which identifies newly postmitotic neurons, a positive correlation was found between the start of differentiation and the onset of PCD. These data indicate that PCD in neuroblast proliferative zones is a universal feature of nervous system development. Moreover, cell death represents a prominent cell fate that may be linked to mechanisms of differentiation.

A single receptor encoded by vzg-1/lpA1/edg-2 couples to G proteins and mediates multiple cellular responses to lysophosphatidic acid

Extracellular lysophosphatidic acid (LPA) produces diverse cellular responses in many cell types. Recent reports of several molecularly distinct G protein-coupled receptors have raised the possibility that the responses to LPA stimulation could be mediated by the combination of several uni-functional receptors. To address this issue, we analyzed one receptor encoded by ventricular zone gene-1 (vzg-1) (also referred to as lpA1/edg-2) by using heterologous expression in a neuronal and nonneuronal cell line. VZG-1 expression was necessary and sufficient in mediating multiple effects of LPA: [3H]-LPA binding, G protein activation, stress fiber formation, neurite retraction, serum response element activation, and increased DNA synthesis. These results demonstrate that a single receptor, encoded by vzg-1, can activate multiple LPA-dependent responses in cells from distinct tissue lineages.

Phylogenetic analysis of the nef gene reveals a distinctive monophyletic clade in Korean HIV-1 cases

To study the genetic variation of the HIV-1 strains prevalent in South Korea, we analyzed the nef sequences derived from 46 HIV-1-positive individuals living in various geographic regions in Korea. Phylogenetic analysis revealed four subtypes of HIV-1: A (3 patients), B (41 patients), D (1 patient), and a type that could not be clearly classified to any known subtype (1 patient). Thirty-five of the 41 Korean subtype B isolates formed a distinct monophyletic clade that is not related to any of the international sequences from the Los Alamos Database or GenBank as of June 1997. Indeed, the presence of unique conserved sequences was identified among the Korean isolates in this Korean subtype B group. The variations in the nucleotide sequences of a majority (32 of 35) subtype B samples within the Korean clade were 1.9% to 8.8%, and amino acid sequences varied from 3.9% to 15.5%. These results suggest that HIV-1 strains currently present in South Korea might have originated from a few sources or might be developing through a certain selective pressure. This is the first report on the molecular nature of the HIV-1 infection present in South Korea.

Nocardia crassostreae sp. nov., the causal agent of nocardiosis in Pacific oysters

Seven strains of bacteria were isolated from Pacific oysters, Crassostrea gigas, with a focal or systemic disease. The strains were aerobic, Gram-positive, acid-fast, produced a mycelium which fragmented into irregular rod-like elements, had a peptidoglycan containing meso-diaminopimelic acid, arabinose and galactose as major sugars, mycolic acids with 46-58 carbon atoms and G + C-rich DNA. All of these properties are consistent with the classification of the organisms in the genus Nocardia. A partial sequence of the 16S rRNA gene of isolate NB4H was determined following isolation and cloning of the PCR-amplified gene. The sequence was aligned with those of representative mycolic-acid-containing taxa and a phylogenetic tree was generated using the neighbour-joining method. It was evident from the phylogenetic tree that the three strains tested, RB1, OB3P and NB4H, were identical and belonged to the Nocardia otitidiscaviarum rRNA sub-group. The biochemical, chemical, morphological and physiological properties of the isolates were also essentially identical and served to distinguish them from representative nocardiae. It is, therefore, proposed that the strains isolated from the diseased Pacific oysters be assigned to a new species, Nocardia crassostreae. The type strain is NB4H (= ATCC 700418).

Arachidonate initiated protein kinase C activation regulates HeLa cell spreading on a gelatin substrate by inducing F-actin formation and exocytotic upregulation of beta 1 integrin

HeLa cell spreading on a gelatin substrate requires the activation of protein kinase C (PKC), which occurs as a result of cell-attachment-induced activation of phospholipase A2 (PLA2) to produce arachidonic acid (AA) and metabolism of AA by lipoxyginase (LOX). The present study examines how PKC activation affects the actin- and microtubule-based cytoskeletal machinery to facilitate HeLa cell spreading on gelatin. Cell spreading on gelatin is contingent on PKC induction of both actin polymerization and microtubule-facilitated exocytosis, which is based on the following observations. There is an increase in the relative content of filamentous (F)-actin during HeLa cell spreading, and treating HeLa cells with PKC-activating phorbol esters such as 12-O-tetradecanoyl phorbol 13-acetate (TPA) further increases the relative content of F-actin and the rate and extent to which the cells spread. Conversely, inhibition of PKC by calphostin C blocked both cell spreading and the increase of F-actin content. The increased F-actin content induced by PKC activators also was observed in suspension cells treated with TPA, and the kinetics of F-actin were similar to that for PKC activation. In addition, PKC epsilon, which is the PKC isoform most involved in regulating HeLa cell spreading in response to AA production, is more rapidly translocated to the membrane in response to TPA treatment than is the increase in F-actin. Blocking the activities of either PLA2 or LOX inhibited F-actin formation and cell spreading, both of which were reversed by TPA treatment. This result is consistent with AA and a LOX metabolite of AA as being upstream second messengers of activation of PKC and its regulation of F-actin formation and cell spreading. PKC appears to activate actin polymerization in the entire body of the cell and not just in the region of cell-substrate adhesion because activated PKC was associated not only with the basolateral plasma membrane domain contacting the culture dish but also with the apical plasma membrane domain exposed to the culture medium and with an intracellular membrane fraction. In addition to the facilitation of F-actin formation, activation of PKC induces the exocytotic upregulation of beta 1 integrins from an intracellular domain to the cell surface, possibly in a microtubule-dependent manner because the upregulation is inhibited by Nocodazole. The results support the concept that cell-attachment-induced AA production and its metabolism by LOX results in the activation of PKC, which has a dual role in regulating the cytoskeletal machinery during HeLa cell spreading. One is through the formation of F-actin that induces the structural reorganization of the cells from round to spread, and the other is the exocytotic upregulation of collagen receptors to the cell surface to enhance cell spreading.

D-AKAP2, a novel protein kinase A anchoring protein with a putative RGS domain

Subcellular localization directed by specific A kinase anchoring proteins (AKAPs) is a mechanism for compartmentalization of cAMP-dependent protein kinase (PKA). Using a two-hybrid screen, a novel AKAP was isolated. Because it interacts with both the type I and type II regulatory subunits, it was defined as a dual specific AKAP or D-AKAP1. Here we report the cloning and characterization of another novel cDNA isolated from that screen. This new member of the D-AKAP family, D-AKAP2, also binds both types of regulatory subunits. A message of 5 kb pairs was detected for D-AKAP2 in all embryonic stages and in all adult tissues tested. In brain, skeletal muscle, kidney, and testis, a 10-kb mRNA was identified. In testis, several small mRNAs were observed. Therefore, D-AKAP2 represents a novel family of proteins. cDNA cloning from a mouse testis library identified the full length D-AKAP2. It is composed of 372 amino acids which includes the R binding fragment, residues 333-372, at its C-terminus. Based on coprecipitation assays, the R binding domain interacts with the N-terminal dimerization domain of RIalpha and RIIalpha. A putative RGS domain was identified near the N-terminal region of D-AKAP2. The presence of this domain raises the intriguing possibility that D-AKAP2 may interact with a Galpha protein thus providing a link between the signaling machinery at the plasma membrane and the downstream kinase.

A novel fibroblast growth factor gene expressed in the developing nervous system is a downstream target of the chimeric homeodomain oncoprotein E2A-Pbx1

Pbx1 is a homeodomain transcription factor that has the ability to form heterodimers with homeodomain proteins encoded by the homeotic selector (Hox) gene complexes and increase their DNA-binding affinity and specificity. A current hypothesis proposes that interactions with Pbx1 are necessary for Hox proteins to regulate downstream target genes that in turn control growth, differentiation and morphogenesis during development. In pre B cell leukemias containing the t(1;19) chromosome translocation, Pbx1 is converted into a strong transactivator by fusion to the activation domain of the bHLH transcription factor E2A. The E2A-Pbx1 fusion protein should therefore activate transcription of genes normally regulated by Pbx1. We have used the subtractive process of representational difference analysis to identify targets of E2A-Pbx1. We show that E2A-Pbx1 can directly activate transcription of a novel member of the fibroblast growth factor family of intercellular signalling molecules, FGF-15. The FGF-15 gene is expressed in a regionally restricted pattern in the developing nervous system, suggesting that FGF-15 may play an important role in regulating cell division and patterning within specific regions of the embryonic brain, spinal cord and sensory organs.

E2A deficiency leads to abnormalities in alphabeta T-cell development and to rapid development of T-cell lymphomas

The E2A gene products, E12 and E47, are critical for proper early B-cell development and commitment to the B-cell lineage. Here we reveal a new role for E2A in T-lymphocyte development. Loss of E2A activity results in a partial block at the earliest stage of T-lineage development. This early T-cell phenotype precedes the development of a T-cell lymphoma which occurs between 3 and 9 months of age. The thymomas are monoclonal and highly malignant and display a cell surface phenotype similar to that of immature thymocytes. In addition, the thymomas generally express high levels of c-myc. As assayed by comparative genomic hybridization, each of the tumor populations analyzed showed a nonrandom gain of chromosome 15, which contains the c-myc gene. Taken together, the data suggest that the E2A gene products play a role early in thymocyte development that is similar to their function in B-lineage determination. Furthermore, the lack of E2A results in development of T-cell malignancies, and we propose that E2A inactivation is a common feature of a wide variety of human T-cell proliferative disorders, including those involving the E2A heterodimeric partners tal-1 and lyl-1.

Png-1, a nervous system-specific zinc finger gene, identifies regions containing postmitotic neurons during mammalian embryonic development

To identify genes associated with early postmitotic cortical neurons, gene fragments were examined for expression in postmitotic, but not proliferative, zones of the embryonic murine cortex. Through this approach, a novel member of the zinc finger gene family, containing 6 C2HC fingers, was isolated and named postmitotic neural gene-1, or png-1. Embryonic png-1 expression was: 1) nervous system-specific; 2) restricted to zones containing postmitotic neurons; and 3) detected in all developing neural structures examined. In the cortex, png-1 expression was first observed on embryonic day 11, correlating temporally and spatially with the known generation of the first cortical neurons. Gradients of png-1 expression throughout the embryonic central nervous system further correlated temporally and spatially with known gradients of neuron production. With development, expression remained restricted to postmitotic zones, including those containing newly-postmitotic neurons. Png-1 was also detected within two days of neural retinoic acid induction in P19 cells, and expression increased with further neuronal differentiation. These data implicate png-1 as one of the earliest molecular markers for postmitotic neuronal regions and suggest a function as a panneural transcription factor associated with neuronal differentiation.

Maternally derived immunoglobulin light chain is present in the fetal mammalian CNS

Toward identifying molecules involved in cell-cell interactions during cerebral cortical development, we have investigated the nature of immunoglobulin-like immunoreactivity (Ig-ir) in the murine cortex. Immunohistochemistry using several antisera recognizing IgG revealed intense immunoreactivity in the subplate and marginal zone of embryonic day 16 cortex, as well as in the hindbrain and spinal cord, particularly within ventral fiber tracts. In three independently derived mouse strains lacking the recombination activating genes RAG-1 or RAG-2, which are essential for Ig production, Ig-ir was absent from the fetal CNS. Western blot analyses of wild-type brains from embryonic day 12 through birth identified a 25 kDa protein that co-migrated with Ig light chain and was absent from RAG-1 or RAG-2 -/- brain samples. This result could be replicated with an antiserum specific for Ig kappa light chain, but not with antisera specific for Ig gamma or mu heavy chain. No Ig-ir was detected in the brains of RAG-1 +/- embryos carried by a -/- female, suggesting a maternal source of the immunoreactive molecule. In confirmation of this, Ig-ir could be partially reproduced by intraperitoneal injection of pregnant RAG-1 -/- females with normal mouse serum. We conclude that maternally derived Ig light chain is present in the fetal murine CNS. This may represent a novel maternal contribution to fetal neural development and implicates Ig molecules as potential mediators of cortical developmental events.

Streptomyces seoulensis sp. nov

The taxonomic position of an actinomycete strain isolated from Korean soil was examined by a polyphasic approach. The isolate, designated IMSNU-1, was clearly assigned to the genus Streptomyces on the basis of morphological and chemotaxonomic data. The test strain was the subject of a probabilistic identification study using the identification matrices generated by Langham et al. (J. Gen. Microbiol. 135:121-133, 1989) and found to be marginally close to clusters 19 and 39. An almost complete 16S rRNA gene (rDNA) sequence was obtained for the test strain and compared with those of representative streptomycetes. 16S rDNA sequence data not only support the strain's membership in the genus Streptomyces but also provide strong evidence that our isolate is genealogically distant from representatives of clusters 19 and 39, forming a separate phyletic line in a clade encompassed by streptomycetes. It is therefore proposed from the polyphasic evidence that strain IMSNU-1 be classified in the genus Streptomyces as Streptomyces seoulensis sp. nov.

Identification of a novel protein kinase A anchoring protein that binds both type I and type II regulatory subunits

Compartmentalization of cAMP-dependent protein kinase is achieved in part by interaction with A-kinase anchoring proteins (AKAPs). All of the anchoring proteins identified previously target the kinase by tethering the type II regulatory subunit. Here we report the cloning and characterization of a novel anchoring protein, D-AKAP1, that interacts with the N terminus of both type I and type II regulatory subunits. A novel cDNA encoding a 125-amino acid fragment of D-AKAP1 was isolated from a two-hybrid screen and shown to interact specifically with the type I regulatory subunit. Although a single message of 3.8 kilobase pairs was detected for D-AKAP1 in all embryonic stages and in most adult tissues, cDNA cloning revealed the possibility of at least four splice variants. All four isoforms contain a core of 526 amino acids, which includes the R binding fragment, and may be expressed in a tissue-specific manner. This core sequence was homologous to S-AKAP84, including a mitochondrial signal sequence near the amino terminus (Lin, R. Y., Moss, S. B., and Rubin, C. S. (1995) J. Biol. Chem. 270, 27804-27811). D-AKAP1 and the type I regulatory subunit appeared to have overlapping expression patterns in muscle and olfactory epithelium by in situ hybridization. These results raise a novel possibility that the type I regulatory subunit may be anchored via anchoring proteins.

Long-term identification of streptomycetes using pyrolysis mass spectrometry and artificial neural networks

Sixteen reference strains and thirteen fresh isolates of three putatively novel Streptomyces species were examined six times over twenty months using pyrolysis mass spectrometry to examine the long-term reproducibility of the procedure. The reference strains and new isolates were correctly identified using information in each of the datasets and operational fingerprinting, but direct statistical comparison of the datasets for strain identification was unsuccessful between datasets. Artificial neural networks were also used to identify the strains held in the datasets. Neural networks trained with pyrolysis mass spectra from a single dataset were found to successfully identify the reference strains and fresh isolates in that dataset but were unable to identify many of the strains in the other datasets. However, a neural network trained on representative pyrolysis mass spectra from each of the first three datasets were found to identify the reference strains and fresh isolates in those three datasets and in the three subsequent datasets. Therefore, artificial neural network analysis of pyrolysis mass spectrometric data can provide a rapid, cost-effective, accurate and long-term reproducible way of identifying and typing microorganisms.

A proposal to reclassify Nocardia pinensis Blackall et al. as Skermania piniformis gen. nov., comb. nov

The type strain of Nocardia pinensis was the subject of chemotaxonomic and 16S ribosomal DNA sequencing studies. The resultant nucleotide sequence was aligned with the sequences of representatives of the genera Corynebacterium, Dietzia, Gordona, Mycobacterium, Nocardia, Rhodococcus, and Tsukamurella, and phylogenetic trees were generated by using the Fitch-Margoliash, maximum-parsimony, maximum-likelihood, and neighbor-joining methods. It was evident from the phylogenetic analyses that N. pinensis represents a distinct phyletic line that is most closely associated with the Gordona clade. This genealogical evidence, together with chemotaxonomic and phenotypic data derived from this and previous studies, indicates that N. pinensis merits generic status within the family Nocardiaceae. Therefore, we propose that N. pinensis Blackall et al. 1989 be reclassified as Skermania piniformis gen. nov., comb. nov. The type strain of Skermania piniformis cleaved an array of conjugated substrates based on the fluorophores 7-amino-4-methylcoumarin and 4-methylumbelliferone.

Ventricular zone gene-1 (vzg-1) encodes a lysophosphatidic acid receptor expressed in neurogenic regions of the developing cerebral cortex

Neocortical neuroblast cell lines were used to clone G-protein-coupled receptor (GPCR) genes to study signaling mechanisms regulating cortical neurogenesis. One putative GPCR gene displayed an in situ expression pattern enriched in cortical neurogenic regions and was therefore named ventricular zone gene-1 (vzg-1). The vzg-1 cDNA hybridized to a 3.8-kb mRNA transcript and encoded a protein with a predicted molecular mass of 41-42 kD, confirmed by Western blot analysis. To assess its function, vzg-1 was overexpressed in a cell line from which it was cloned, inducing serum-dependent "cell rounding." Lysophosphatidic acid (LPA), a bioactive lipid present in high concentrations in serum, reproduced the effect seen with serum alone. Morphological responses to other related phospholipids or to thrombin, another agent that induces cell rounding through a GPCR, were not observed in vzg-1 overexpressing cells. Vzg-1 overexpression decreased the EC50 of both cell rounding and Gi activation in response to LPA. Pertussis toxin treatment inhibited vzg-1-dependent LPA-mediated Gi activation, but had no effect on cell rounding. Membrane binding studies indicated that vzg-1 overexpression increased specific LPA binding. These analyses identify the vzg-1 gene product as a receptor for LPA, suggesting the operation of LPA signaling mechanisms in cortical neurogenesis. Vzg-1 therefore provides a link between extracellular LPA and the activation of LPA-mediated signaling pathways through a single receptor and will allow new investigations into LPA signaling both in neural and nonneural systems.

Widespread programmed cell death in proliferative and postmitotic regions of the fetal cerebral cortex

A key event in the development of the mammalian cerebral cortex is the generation of neuronal populations during embryonic life. Previous studies have revealed many details of cortical neuron development including cell birthdates, migration patterns and lineage relationships. Programmed cell death is a potentially important mechanism that could alter the numbers and types of developing cortical cells during these early embryonic phases. While programmed cell death has been documented in other parts of the embryonic central nervous system, its operation has not been previously reported in the embryonic cortex because of the lack of cell death markers and the difficulty in following the entire population of cortical cells. Here, we have investigated the spatial and temporal distribution of dying cells in the embryonic cortex using an in situ endlabelling technique called ‘ISEL+’ that identifies fragmented nuclear DNA in dying cells with increased sensitivity. The period encompassing murine cerebral cortical neurogenesis was examined, from embryonic days 10 through 18. Dying cells were rare at embryonic day 10, but by embryonic day 14, 70% of cortical cells were found to be dying. This number declined to 50% by embryonic day 18, and few dying cells were observed in the adult cerebral cortex. Surprisingly, while dying cells were observed throughout the cerebral cortical wall, the majority were found within zones of cell proliferation rather than in regions of postmitotic neurons. These observations suggest that multiple mechanisms may regulate programmed cell death in the developing cortex. Moreover, embryonic cell death could be an important factor enabling the selection of appropriate cortical cells before they complete their differentiation in postnatal life.

Clonal cell lines produced by infection of neocortical neuroblasts using multiple oncogenes transduced by retroviruses

Toward understanding the early molecular development of neocortical neurons, we report the generation of two clonal murine cell lines derived by sequential oncogenic retroviral infection of neocortical neuronal precursors. The resulting cell lines stably express the telencephalon-specific gene BF-1 and a gene enriched in the neocortical ventricular zone, vzg-1. They also express early neuronal but not glial markers, possess neuron-like processes without chemical synapses by ultrastructure, and appear pyramidal or bipolar with processes resembling apical dendrites, bifurcating and beaded axons, or growth cones. Immortalization appears to have occurred through the expression of oncogene combinations SV40 large T with vras or SV40 large T with both vsrc and vmyc. These cell lines may represent developing neocortical neuroblasts blocked from complete differentiation, and they should be useful in the isolation and analysis of genes involved in early neocortical development.

Evolution of a legacy system to a Web patient record server: leveraging investment while opening the system

A layered system is under development to enhance our legacy system as a backend in a WEB-enabled system. Each layer of the system has defined functionality, leverages the investment in the layer below, and follows the strategy of reducing support requirements for workstations. The mainframe system provides administrative integration of sub-systems, security, and the central data repository for most information. The second layer is a graphical user interface (GUI) to the system for Windows platforms. Support needs are limited by relying chiefly on X-terminals and application servers. The "Intranet" layer is a WEB Server building upon the second layer gateways to provide platform-independent access to selected information and images. The fourth layer, under evaluation, will extend access to the central data repository for Internet users of web browsers that support private-key/public-key encryption.

Effect of mosquito age and reproductive status on melanization of sephadex beads in Plasmodium-refractory and -susceptible strains of Anopheles gambiae

Malaria-refractory and -susceptible strains of the mosquito vector, Anopheles gambiae, differ in their response to negatively-charged Sephadex CM-25 beads. CM-25 beads elicit a much stronger melanization reaction in refractory mosquitoes than in susceptible mosquitoes. Light microscopic and scanning electron microscopic studies documented a progression from early stages with small spots of melanin adhering to CM-25 beads to late stages where spots had grown and coalesced to form a dark dense capsule. This reaction occurred maximally during the first 18 hr after inoculation; female mosquitoes aged 3-5 days showed 48% of beads heavily melanized by 18 hr postinoculation in the refractory strain and 0-10% in the susceptible strain. Female mosquito age and reproductive status strongly affected the ability to melanize beads. All of the beads were completely melanized in the refractory strain on the day immediately following eclosion (Day 0); thereafter these levels decreased steadily until the last time point on Day 7, when only 23% of beads were melanized in this strain. In the susceptible strain, 53% of beads were heavily melanized on Day 0 and 0-10% were melanized at all other times. At Day 1 and 2 after blood feeding, 85 and 88% of beads, respectively, were heavily melanized in refractory females in comparison with control mosquitoes of the same age which heavily melanize 23-58% of the beads. Blood feeding had little effect on the ability to melanize beads in the susceptible strain.

Chronic innominate artery dissection after blunt thoracic trauma: case report

Blunt innominate chest trauma is relatively rare, with only 70 cases being reported in the surgical literature since 1960. This report describes a 20-year-old male who sustained a blunt chest injury that resulted in an innominate artery dissection. The patient's clinical course and management are discussed, as well as a review of the surgical literature.

A phylogenetic analysis of the genus Nocardia with 16S rRNA gene sequences

Partial sequences of the 16S rRNA genes of the type strains of nine species of the genus Nocardia were determined following the isolation and cloning of the amplified genes. These sequences were aligned with the sequences of representatives of the genera Corynebacterium, Gordona, Mycobacterium, Rhodococcus, and Tsukamurella, and phylogenetic trees were inferred by using the Fitch-Margoliash and neighbor-joining methods. The genus Nocardia formed a distinct clade that was most closely associated with the genus Rhodococcus. The average level of sequence similarity found among the type strains of the Nocardia species was 97.2 +/- 0.7%. Two sublines were recognized within the Nocardia clade; one encompassed Nocardia asteroides and related species, and the other encompassed Nocardia otitidiscaviarum and allied taxa. Separation of the two sublines is based on differences in helix 37-1. The results of isoprenoid quinone analyses provided evidence that nocardiae can be distinguished from all other actinomycete taxa on the basis of their characteristic menaquinone profiles. Nocardiae typically contain hexahydrogenated menaquinones with eight isoprene units in which the two end units are cyclized.