Comparative recovery of uninjured and heat-injured Listeria monocytogenes cells from bovine milk

The standard selective enrichment protocols of the Food and Drug Administration (FDA) and U.S. Department of Agriculture (USDA) were compared with an experimental nonselective broth enrichment (NSB) protocol and variations of the standard cold-enrichment (CE) protocol for the recovery of heat-injured Listeria monocytogenes. Bacterial cells (10(7)/ml) were suspended in sterile milk and heated at 71.7 degrees C in a slug-flow heat exchanger for holding times ranging from 1 to 30 s. Surviving cells were determined (50% endpoint) by the given protocols, and the following D values were obtained: NSB, D = 2.0 +/- 0.5 s; FDA, D = 1.4 +/- 0.3 s; USDA, D = 0.6 +/- 0.2 s; CE, D less than or equal to 1.2 s. The respective direct-plating media used in these enrichments were also analyzed for recovery, and the following D values were calculated from the enumeration of surviving cells; NSB, D = 2.7 +/- 0.8 s; FDA, D = 1.3 +/- 0.4 s; USDA, D = 0.7 +/- 0.2 s. The low levels of heat-injured L. monocytogenes cells which were detected at inactivation endpoints on the optimal nonselective media (25 degrees C for 7 days) failed to recover and multiply during experimental CEs (4 degrees C for 28 days). Initial inactivation experiments in which raw whole milk was used as the heating menstruum gave much lower recoveries with all protocols. The detectable limits for uninjured cells that were suspended in raw milk were similar (0.35 to 3.2 cells per ml) for the standard CE, FDA, and USDA protocols.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pathways to inflammation induced by immune complexes: development of the Arthus reaction

The changes associated with inflammation induced by immune complexes (reversed passive Arthus reaction induced with egg albumin-anti-egg albumin) were quantitated and the kinetics of the various vascular phenomena were ascertained. Hyperemia, increase in vascular permeability, platelet accumulation, and polymorphonuclear (PMN) leukocyte accumulation occurred relatively early after induction of the inflammatory lesions, and peaked in 2-4 h. Hemorrhage peaked in 6-h-old lesions. Morphological studies confirmed that almost all infiltrating cells were PMN leukocytes and immunofluorescent tracer studies showed immune complexes in vessel walls as early as 15 min after i.v. injection of the fluoresceinated antigen and the intradermal injection of antibody. By 8 h the progression of the lesions had subsided and by 24 h there were signs of resolution. A pathway for the development of the inflammatory lesions induced with immune complexes is proposed.     

Production of an aromatic aldehyde oxidase by Streptomyces viridosporus

Streptomyces viridosporus strain T7A, when grown in liquid media containing yeast extract and aromatic aldehydes, oxidized the aromatic aldehydes to the corresponding aromatic acids. Benzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, and protocatechualdehyde were catabolized further via the -ketoadipate and gentisate pathways. Dehydrodivanillin, isophthalaldehyde, salicylaldehyde, syringaldehyde, terephthalaldehyde, vanillin, and veratraldehyde were oxidized only as far as the corresponding aromatic acids. Phthalaldehyde and aliphatic aldehydes were not oxidized. The aromatic aldehyde oxidase, which was produced by cultures grown in either the presence or absence of aromatic aldehydes, was partially purified by ammonium sulfate precipitation and ion-exchange chromatography. It consumed molecular oxygen, oxidized aromatic aldehydes to aromatic acids, and produced hydrogen peroxide all in equimolar amounts.Paper no. 81515 of the Idaho Agricultural Experiment Station     

Population structure and admixture in transplanted Tlaxcaltecan populations

The history of the Indian populations from the Valley of Tlaxcala since the Spanish conquest of Mexico has been one of fission and transplantation. A number of Tlaxcaltecan families were relocated by the Spanish and founded new communities such as Saltillo and Cuanalan outside the Valley of Tlaxcala. The contemporary genetic structure of these people reflects their ethnohistory. Genetic distances between Tlaxcaltecan groups are the result of differential systematic pressure acting upon them.     

Flavonoid chemistry of Coreopsis grandiflora (Compositae)

The leaf flavonoid chemistryof Coreopsis grandiflora, which includes var.harveyana, var.longipes, var.saxicola and the typical var.grandiflora, is quite uniform with 6-hy-droxyquercetin 7-O-glucoside, luteolin 7-O-glucoside, marein-maritimein chal-cone-aurone pair and lanceolin-leptosin chalcone-aurone pair as consistent com-ponents. Flavonoid data lend support to the hypothesis that the hexaploid var.longipes originated from parents which would be included withinC. grandiflora, i.e., there is no evidence that other species were involved in its formation. One population of var.grandiflora and several collections of var.saxicola contain additional flavonoid components in the form of flavonol 3-O-glycosides. In nearly all instances the additional compounds are attributable to hybridization withC. lanceolata orC. pubescens because these flavonols are characteristic of these two species and morphological considerations also suggest it. Flavonoid chemistry supports the treatment of var.saxicola as a variety ofC. grandiflora rather than as a distinct species.     

Leaf flavonoid chemistry of Coreopsis (Compositae) section Palmatae

Examination of leaf flavonoids of all taxa ofCoreopsis sectionPalmatae revealed that most members synthesize an array of common flavone (mostly luteolin and apigenin) glycosides. Each diploid species or diploid member of a species is characterized by a particular ensemble of compounds. These taxa includeC. major, C. verticillata, C. pulchra, C. palmata, andC. tripteris. The latter species differs from all other taxa in producing flavonol (kaempferol and quercetin) glycosides and what appear to be 6-oxygenated compounds. Tetraploids ofC. verticillata exhibit the same flavonoids as diploid members of the species, thus flavonoid chemistry supports the hypothesis that they originated from diploids within the species. Certain populations of hexaploid and octoploidC. major are similar chemically to diploids, suggesting they also originated as intraspeciflc polyploids. Other populations of these polyploids exhibit a flavonoid profile which differs from the profile of the diploids, and this profile is nearly identical to the octoploidCoreopsis × delphinifolia. The latter taxon has been viewed by Smith (1976) and Mueller (1974) as an interspecific hybrid betweenC. verticillata andC. major and/orC. tripteris. Species-specific compounds from the former species occur inC. × delphinifolia but no compounds unique to either of the latter two species are discernable. Flavonoid chemistry is not useful in ascertaining whether either or both species have been involved withC. verticillata in producing plants referable toC. × delphinifolia. There is morphological intergradation between octoploidC. major andC. × delphinifolia, and all plants not appearing to be “pure”C. major exhibit a flavonoid chemistry likeC. × delphinifolia. All plants of sectionPalmatae considered to be alloploids (includingC. × delphinifolia) produce the same array of leaf flavonoids, including several “novel” compounds not expressed in the putative parental taxa. Two of the “novel” flavonoids are present in the geographically restricted diploidC. pulchra. The systematic and phylogentic significance of this is not readily apparent.     

Novel ceramide analogues display selective cytotoxicity in drug-resistant breast tumor cell lines compared to normal breast epithelial cells.

The sphingolipid ceramide is involved in diverse cell signaling pathways related to proliferation and differentiation. Elevated ceramide also triggers apoptosis. Synthetic ceramide derivatives have been shown to be cytotoxic to tumors, yet few studies have evaluated whether cytotoxicity of synthetic ceramides is selective for tumor cells. We have evaluated the cytotoxic potency of several novel ceramide analogues in the drug-resistant breast tumor cell lines, SKBr3 and MCF-7/Adr, and compared their cytotoxicity in normal breast epithelial cells. Cytotoxicity was assessed using release of lactate dehydrogenase into the culture medium. (2S, 3S)-3-(6'-Dodecylpyridin-2'-yl)-2-butanoylamidopropane-1,3-diol (pyridine-C4-ceramide) produced non-selective cytotoxicity across the three cell types (EC50= 12.8-16.7 microM, at 24 hr). However, 2S,5R-2-(octanoylamido-(3E))-octadecene-1,5-diol (5R-OH-3E-C8-ceramide), (2S,3R)-2-(N-adamantoyl)-(4E)-octadecen-1,3-diol (adamantyl-ceramide), and (2S,3R)-3-(3'-dodecylphenyl)-2-butanoylamidopropane-1,3-diol (benzene-C4-ceramide) exhibited increased cytotoxicity in the tumor cell lines compared to the normal breast epithelial cells. The EC50 values (microM) at 24 hr for these compounds in SKBr3 cells, MCF-7/Adr cells, and normal breast epithelial cells, respectively, were as follows: 5R-OH-3E-C8-ceramide, 18.3, 21.2 and 58.7; adamantyl-ceramide, 10.9, 24.9 and >100; benzene-C4-ceramide, 18.9, 45.5 and >100. At a concentration of 30 microM, the fold increase in cytotoxicity in breast tumor cell lines compared with normal breast epithelial cells was as follows: 5R-OH-3E-C8-ceramide, 23.7 and 19; adamantyl-ceramide, 11.2 and 10.3 and benzene-C4-ceramide, 79.3 and 77.2, for SKBr3 and MCF-7/Adr cells, respectively. Possible mechanisms accounting for selectivity are discussed. Ceramide analogues with relatively selective toxicity against tumor cells may have potential as therapeutic agents. Elucidating the mechanisms of selective cytotoxicity could identify novel targets that may lead to development of anti-neoplastic agents with a higher therapeutic index.     

Spatial/temporal variations in shrub thicket soil seed banks on an Atlantic Coast barrier island

Potential species replacement within low-diversity shrub thicket communities was investigated for a Virginia barrier island. Seed bank species composition was quantified in a glasshouse study using soil samples collected beneath closed Myrica cerifera thickets, as well as from thicket gaps. Samples were collected from productive and aging thickets, corresponding to differences in soil age. These data were compared to species presently occurring within the thickets and gaps. Seedbank species composition was not indicative of current community composition for either the intact thickets or the gaps. Seed banks resembled a more pioneer community. Thirteen families, 23 genera, and 25 species were identified from the seed bank beneath the M. cerifera thickets. Four species were woody. The within-gap seed bank included 19 families, 30 genera, and 34 species. Eight species were woody. The current community included 21 families, 33 genera, and 36 species beneath the intact thickets as well as within the thicket gaps. Eighteen species were woody. The species richness of gaps was more than three times that of intact thickets. For low-diversity shrub thickets, gaps enhance species richness.     

The Highly Conserved, Coregulated SNO and SNZ Gene Families in Saccharomyces cerevisiae Respond to Nutrient Limitation

SNZ1, a member of a highly conserved gene family, was first identified through studies of proteins synthesized in stationary-phase yeast cells. There are three SNZ genes in Saccharomyces cerevisiae, each of which has another highly conserved gene, named SNO (SNZ proximal open reading frame), upstream. The DNA sequences and relative positions of SNZ and SNO genes have been phylogenetically conserved. This report details studies of the expression of the SNZ-SNO gene pairs under various conditions and phenotypic analysis of snz-sno mutants. An analysis of total RNA was used to determine that adjacent SNZ-SNO gene pairs are coregulated. SNZ2/3 and SNO2/3 mRNAs are induced prior to the diauxic shift and decrease in abundance during the postdiauxic phase, when SNZ1 and SNO1 are induced. In snz2 snz3 mutants, SNZ1 mRNA is induced prior to the diauxic shift, when SNZ2/3 mRNAs are normally induced. Under nitrogen-limiting conditions, SNZ1 mRNAs accumulate in tryptophan, adenine, and uracil auxotrophs but not in prototrophic strains, indicating that induction occurs in response to the limitation of specific nutrients. Strains carrying deletions in all SNZ-SNO gene pairs are viable, but snz1 and sno1 mutants are sensitive to 6-azauracil (6-AU), an inhibitor of purine and pyrimidine biosynthetic enzymes, and methylene blue, a producer of singlet oxygen. The conservation of sequence and chromosomal position, the coregulation and pattern of expression of SNZ1 and SNO1 genes, and the sensitivity of snz1 and sno1 mutants to 6-AU support the hypothesis that the associated proteins are part of an ancient response to nutrient limitation.     

Synonymy in peperomia berteroana (Piperaceae) results in biological disjunction between Pacific and Atlantic oceans

Placing Peperomia berteroana of the Juan Fernandez Islands in the Pacific Ocean in synonymy with P. tristanensis of Tristan da Cunha in the Atlantic Ocean results in a species with a wide geographical disjunction of more than 5000 km. Morphological data indicate that these taxa are best treated as subspecies (P. berteroana subsp. berteroana and P. berteroana subsp. tristanensis).