Nitrogen-deficient Medium in the Differential Isolation of Klebsiella and Enterobacter from Feces

On a nitrogen-deficient agar medium, the tribe Klebsielleae formed large, glistening, mucoid colonies which were easily distinguished from other colony types. Of 113 Klebsielleae isolates from human feces which were characterized, Klebsiella accounted for 88% of the total; 75% were K. pneumoniae; K. ozaenae (13%) was isolated from one individual only. The remaining strains (12%) were identified as Enterobacter cloacae. Counts (for the tribe) ranged from 10(2) to 10(6), with a median of 10(4); 9 of 53 stool specimens were negative. K. pneumoniae was also isolated from 6 of 41 frozen foil-pack foods. Anaerobic studies at room temperature and 37 C revealed no appreciable differences from aerobic plates. The nitrogen-deficient medium appeared better than E M B for isolation of Klebsielleae when they were present in low numbers relative to other coliforms; slime production by Klebsielleae concomitant with minimal growth of other bacteria is involved.     

Zytoplasmatische Filamente in den quergestreiften Muskelzellen des kaudalen Lymphherzens von Rana temporaria L.

Zusammenfassung Die quergestreiften Muskelzellen im Lymphherzen von Rana temporaria werden von etwa 60 AE dicken Filamenten durchzogen, die den Aktinfilamenten ähnlich sind. Sie bilden ein Netzwerk, das unter dem Sarkolemma zirkulär verläuft und mit queren Zügen die Z-Streifen der Myofibrillen untereinander und mit der Zellmembran verbindet. Aktinfilamente der Myofibrillen strahlen in das Netzwerk ein. Die Filamente haben Beziehung zum Sarkoplasmaretikulum und seinen Anlagerungen (Enhapsen) an die sarkolemmalen Einstülpungen (T-System). Das tonofibrillenartige System dient vermutlich der Aufnahme von quer zu den Myofibrillen gerichteten Kräften, unterstützt so den Ablauf der gerichteten Kontraktion der Weichteilmuskulatur des Lymphherzens und erhält die Lage und Ordnung der intrazellulären Strukturen.Im Zusammenhang mit den zytoplasmatischen Filamenten wird hingewiesen auf die sog. Z-Brücken (Garamvölgyi), die Krausesche Grundmembran, die Spiralbinden (Ringbinden) und die leptomeren Myofibrillen (Thoenes und Ruska), die zeigen, daß Muskelzellen passiv wirksame (Filamente im Lymphherzen) und aktiv wirksame (Ringbinden) Quersysteme zur Aufnahme bzw. Ausübung von quergerichteten Kräften auszubilden vermögen.

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Summary A net of filaments of about 60 Å diameter, similar to actin filaments, is observed in cross striated muscle cells in the lymph heart of Rana temporaria L. The filaments form circular strands beneath the sarcolemma. They connect the Z-regions of myofibrils and make contact with the sarcoplasmic reticulum, specially where it is attached to the sarcolemmal invaginations (enhapsis). It is supposed that the filaments resist mechanical forces perpendicular to the myofibrils and keep cellular structures in the right place.In relation to these filaments the Z-bridges (Garamvölgyi), Krauses Grundmembran, Ringbinden und leptomere myofibrils (Thoenes and Ruska) are discussed. It is concluded that muscle cells are capable to develop non contractile (filaments in the lymph heart) or contractile (Ringbinden) systems in response to forces acting perpendicular to the regular myofibrils.

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Die Untersuchungen wurden mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft durchgeführt.

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Herrn Prof. Dr. med. Kurt Goerttler zum 70, Geburtstag gewidmet.     

Agar Concentration in Counting Clostridium Colonies

Decreasing the agar concentration of a counting medium from the usual 1.5% resulted in larger colonies with less interference from gas in Clostridium botulinum 115B and C. sporogenes PA 3679. Optimal agar concentration was 0.65% for C. botulinum with 24-hr incubation and 0.50% for C. sporogenes with 48-hr incubation. Lower concentrations yielded growth too diffuse for counting. Motility was considered the explanation for increased colony size in softer agar. The greater the degree of motility, the greater would be the diffusibility expected, and thus the higher the agar concentration required to insure discrete colonies. For quantitating motility, evaluations were made by use of microscopic examination of liquid cultures and rate of diffusion in a semisolid medium. With both criteria, the degree of motility of C. botulinum 115B clearly exceeded that of C. sporogenes PA 3679. Small-colony variants of C. botulinum in 0.65% agar yielded only small colonies on subculture, with a corresponding decrease in degree of motility of the cells by both criteria. Colony size of the nonmotile C. perfringens ATCC 3624 was unaffected by lowered agar concentrations.     

Evidence for nerve growth factor-mediated paracrine effects in human epidermis

Nerve growth factor (NGF) is critical to the development and maintenance of the peripheral nervous system, but its possible roles in other organ systems are less well characterized. We have recently shown that human epidermal melanocytes, pigment cells derived from the neural crest, express the NGF receptor (p75 NGF-R) in vitro (Peacocke, M., M. Yaar, C. P. Mansur, M. V. Chao, and B. A. Gilchrest. 1988. Proc. Natl. Acad. Sci. USA. 85:5282-5286). Using cultured human skin-derived cells we now demonstrate that the melanocyte p75 NGF-R is functional, in that NGF stimulation modulates melanocyte gene expression; that exposure to an NGF gradient is chemotactic for melanocytes and enhances their dendricity; and that keratinocytes, the dominant epidermal cell type, express NGF messenger RNA and hence are a possible local source of NGF for epidermal melanocytes in the skin. These combined data suggest a paracrine role for NGF in human epidermis.     

Further evidence for a separate enzymic entity for the synthesis of homocitrulline, distinct from the regular ornithine transcarbamylase

Differential digitonin extraction of rat liver mitochondria and of mitochondria of livers of affected and unaffected male sparse fur mice released a lysine transcarbamylase activity from the mitochondria at a digitonin to protein ratio in between that for myokinase and glutamate dehydrogenase, but at a slightly lower ratio than the ornithine transcarbamylase activity. Homocitrulline formation by isolated rat liver mitochondria is independent of the uptake of lysine by mitochondria as evidenced by the insensitivity of homocitrulline formation to changes in the matrix pH, in contrast to citrulline formation from ornithine. High-performance liquid chromatography separates the lysine transcarbamylase activity from the ornithine transcarbamylase activity. It is concluded that the lysine transcarbamylase activity is localized outside the inner mitochondrial membrane.     

In Vivo Transfer of cellular immunity to primates with transfer factor prepared from human or primate leucocytes

Dialyzable transfer factor (TF_d) prepared from a human donor and transfer factor (TF) from baboon whole cell lysates was administered to 3 species of nonhuman primates: baboons, cebus monkeys and marmosets. In vivo transfer was evaluated with in vivo skin test and in vitro blastogenic responses to multiple antigens. Transfer of cellular reactivity in all three nonhuman primate species was demonstrated with both human TF_d and baboon TF. A cumulative conversion rate of 45% for skin test responses and 65% for lymphocyte blastogenesis was demonstrated following human TF_d injection while conversion was 17% and 33% respectively following baboon TF. Specificity was supported by the absence of conversion to TF donor negative antigens. There were no signficant differences observed between the 3 recipient primate species.     

Extraction of thromboxane B2 from urine using an immobilized antibody column for subsequent analysis by gas chromatography-mass spectrometry

This paper describes an antibody affinity (immunoaffinity) column which, in one step, extracts and sufficiently purifies urinary thromboxane B2 (TXB2) for quantitative analysis by high resolution gas chromatography-negative ion chemical ionization-selected ion monitoring-mass spectrometry (HRGC-NICI-SIM-MS). Polyclonal TXB2 antibody from rabbit was partially purified using immobilized Staphylococcus aureus Protein A. The purified IgG fraction was then immobilized using an N-hydroxysuccimidyl silica gel. The resulting matrix bound 570 ng TXB2 per ml of gel. TXB2 was quantitatively eluted with acetonitrile-water (19:1). Columns constructed from the gel could be used repeatedly since binding capacity was reconstituted using 0.01 M phosphate buffer (pH 7.4) with no apparent loss of activity. Using these columns, urinary TXB2 was sufficiently purified in one step such that in subsequent analysis by HRGC-NICI-SIM-MS interference free chromatograms were observed.     

Cryptic lineages and potential introgression in a mixed-ploidy species (Phragmites australis) across temperate China

Polyploidization and hybridization are very common in natural plant species, and mixed-ploidy species provide a unique opportunity to study the effects of evolutionary history, local abundance, and ploidy level on the direction and extent of introgression between intraspecific lineages. First, we delimited two morphologically cryptic lineages of Phragmites australis Trin. ex Steud. in temperate China using 11 nuclear microsatellites and two chloroplast DNA fragments with 225 samples from China as well as 11 samples from Oceania and Europe. Our evidence supported that haplotype O and haplotype P were two relatively independent lineages with low and high ploidy levels, respectively; haplotype M might be ancient and could have undergone a complex evolutionary history. Then we examined the lineage divergence and compared the introgression patterns between two major lineages along geographical and abundance gradients with a large number of samples (n = 1067) collected from China. The sympatric coexistence of two lineages in north and northeast China implies an ongoing or potential introgression between them. Cline analysis showed that the level of genetic admixture were significantly correlated with longitude rather than latitude. Our results also suggested that ploidy level could deeply influence the introgression asymmetry, and the effect of the current local abundance on introgression might be covered by the past coexistence time driven by phylogeographic history. Our study draws a baseline for future research on the ecological and evolutionary consequences of migration and introgression of Chinese P. australis under global change.     

Development of the peripheral glial cells in Drosophila

In complex organisms the nervous system comprises two cell types: neurons and glial cells. Their correct interplay is of crucial importance during both the development of the nervous system and for later function of the nervous system. In recent years tools have been developed for Drosophila that enable genetic approaches to understanding glial development and differentiation. Focusing on peripheral glial cells we first summarize wild-type development, then introduce some of the relevant genes that have been identified. Despite obvious differences between Drosophila and mammalian glial cells, the molecular machinery that controls terminal differentiation appears well conserved.