Deep Sea Research Part Ii Topical Studies in Oceanography, Sep 1, 2008
Variability in the temporal-spatial distribution and abundance of zooplankton was documented each... more Variability in the temporal-spatial distribution and abundance of zooplankton was documented each summer on the Palmer Long-Term Ecological Research (LTER) grid west of the Antarctic Peninsula between Anvers and Adelaide Islands during a 12-yr time series. Oblique tows ...
Deep Sea Research Part A. Oceanographic Research Papers, 1992
Abstract A time-and temperature-dependent model was developed to simulate the descent-ascent beha... more Abstract A time-and temperature-dependent model was developed to simulate the descent-ascent behavior of the embryos and early larval stages of the Antarctic krill, Euphausia superba. This model combines laboratory measurements of temperature effects on ...
ABSTRACT ABSTRACT: The Palmer Long Term Ecological Research study region west of the Antarctic Pe... more ABSTRACT ABSTRACT: The Palmer Long Term Ecological Research study region west of the Antarctic Peninsula is experiencing warming and changing seasonal sea ice dynamics. Abundance patterns of 3 species of pelagic secondary producers were analyzed for trends, cycles, range extensions or shifts in the location of highest density, and for changes in population dynamics over a 16 yr period (1993−2008). Species analyzed represented different hydrographic regimes and are known to have contrasting responses to seasonal sea ice dynamics: krill Euphausia superba, seasonal sea ice zone; tunicates Salpa thompsoni, warmer waters with minimal sea ice; and larval Antarctic silverfish Pleuragramma antarcticum, cold continental shelf waters. Cycles were observed in grid-wide abundance and recruitment for E. superba. Maximum grid-wide densities did not decrease, but the location of highest densities shifted southward 200 km, away from Adélie penguin rookeries at the northern end. A distinct change post-1999 was apparent in the frequency of occurrence and abundance of S. thompsoni. Mixtures of krill and salps became common, but neither peak densities nor the frequency of peak years for salps increased. As with Antarctic krill, highest salp densities shifted southward alongshore. Larval P. antarcticum were abundant in the northern coastal region in the early 1990s, but virtually disappeared in that region after 1999/2000. Possible mechanisms underlying these observations include the southerly movement of the sea ice edge during spring, changes in proximity of source populations (salps), and changes in transport pathways (larval P. antarcticum). Patterns are compared to those in the SW Atlantic.
Group B Streptococcus (GBS) is the leading cause of bacterial sepsis and meningitis among neonate... more Group B Streptococcus (GBS) is the leading cause of bacterial sepsis and meningitis among neonates. While the capsular polysaccharide (CPS) is an important virulence factor of GBS, other cell surface components, such as C proteins, may also play a role in GBS disease. CPS production by GBS type III strain M781 was greater when cells were held at a fast (1.4-h mass-doubling time [td]) than at a slow (11-h td) rate of growth. To further investigate growth rate regulation of CPS production and to investigate production of other cell components, different serotypes and strains of GBS were grown in continuous culture in a semidefined and a complex medium. Samples were obtained after at least five generations at the selected growth rate. Cells and cell-free supernatants were processed immediately, and results from all assays were normalized for cell dry weight. All serotypes (Ia, Ib, and III) and strains (one or two strains per serotype) tested produced at least 3.6-fold more CPS at a td ...
The capsular polysaccharide (CPS) of group B streptococci (GBS) is an important virulence factor ... more The capsular polysaccharide (CPS) of group B streptococci (GBS) is an important virulence factor that also serves to protect cells from nonspecific host defense mechanisms. Expression of CPS by GBS, as with other encapsulated bacterial pathogens, is not constitutive but varies during growth in vitro and in primary cultures isolated from different sites of infection. Despite this understanding, little is known about regulation of this surface-expressed carbohydrate antigen in GBS. Here we report that expression of type III CPS by GBS strain M781 grown in continuous culture with a modified chemically defined medium is regulated by growth rate. Cells in steady state at mass doubling times (tds) of 0.8, 1.4, and 1.6 h expressed an average of sixfold more cell-associated CPS than did cells held at tds of 2.3 and 11 h. Strain M781 grown at a td of 1.4 h repeatedly produced more type III CPS than those held at a td of 11.0 h, even when limited for glucose, pyridoxamine, or thiamine. In our...
Three statistical models that predict microbial interactions within the vaginal environment are p... more Three statistical models that predict microbial interactions within the vaginal environment are presented. A large data set was assembled from in vivo studies describing the healthy vaginal environment, and the data set was analyzed to determine whether statistical models which would accurately predict the interactions of the microflora in this environment could be formulated. During assembly of the data set, two new variables were defined and were added to the data set, that is, cycle (sequence of menstrual cycle) and flow stage (subdivision of cycle determined by day of menstrual cycle). Concentrations of total aerobic (includes facultative) bacteria, total anaerobic bacteria, and a Corynebacterium sp. were identified by correlation analysis as variables with significant predictors. By using a regression method with a backward elimination procedure, significant predictors of these outcome variables were identified as the concentrations of Lactobacillus spp., anaerobic Streptococcu...
In this study we identified subgroups of observations relating to the healthy vaginal microbiota.... more In this study we identified subgroups of observations relating to the healthy vaginal microbiota. This microbiota resides in a dynamic environment that undergoes cyclic change during the menstrual cycle. Cluster analysis procedures were applied to divide a set of 226 normal microbiota observations into groups. Three subgroups containing 100, 65, and 61 observations were identified. Plots of principal components determined by canonical analysis were obtained to demonstrate graphically the clustering of normal vaginal microbiota observations into subgroups. Results from the cluster analyses were verified using a predictive logit regression model. Analysis of mean logit values for the three clusters demonstrated that they differed from each other. Further verification was obtained using data from women with abnormal vaginal microbiota, either due to a yeast infection or the use of an iodine-based medicated douche product, and applying them to the clustering results developed using the ...
Herein we report studies with a novel combination vaccine that, when administered to mice, confer... more Herein we report studies with a novel combination vaccine that, when administered to mice, conferred protection against highly virulent strains of Francisella tularensis by stimulating both arms of the immune system. Our earlier studies with Ft.LVS::wbtA, an O-polysaccharide (OPS)-negative mutant derived from the available live vaccine strain of F. tularensis (Ft.LVS), elucidated the role of antibodies to the OPS - a key virulence determinant - in protection against virulent type A organisms. However, when expressed on the organism, the OPS enhances virulence. In contrast, in purified form, the OPS is completely benign. We hypothesized that a novel combination vaccine containing both a component that induces humoral immunity and a component that induces cellular immunity to this intracellular microbe would have an enhanced protective capacity over either component alone and would be much safer than the LVS vaccine. Thus we developed a combination vaccine containing both OPS (supplie...
Page 1. Phycologia (1995) Volume 34 (5), 424-430 Vertical distribution of Antarctic peninsular ma... more Page 1. Phycologia (1995) Volume 34 (5), 424-430 Vertical distribution of Antarctic peninsular macroalgae: cover, biomass and species composition* CHARLES D. AMSLER!, ROBERT J. ROWLEy2, DAVID R. LAUR2, LANGDON B. QUETIN2 AND ROBIN M. Ross2 ...
Deep Sea Research Part Ii Topical Studies in Oceanography, Sep 1, 2008
Variability in the temporal-spatial distribution and abundance of zooplankton was documented each... more Variability in the temporal-spatial distribution and abundance of zooplankton was documented each summer on the Palmer Long-Term Ecological Research (LTER) grid west of the Antarctic Peninsula between Anvers and Adelaide Islands during a 12-yr time series. Oblique tows ...
Deep Sea Research Part A. Oceanographic Research Papers, 1992
Abstract A time-and temperature-dependent model was developed to simulate the descent-ascent beha... more Abstract A time-and temperature-dependent model was developed to simulate the descent-ascent behavior of the embryos and early larval stages of the Antarctic krill, Euphausia superba. This model combines laboratory measurements of temperature effects on ...
ABSTRACT ABSTRACT: The Palmer Long Term Ecological Research study region west of the Antarctic Pe... more ABSTRACT ABSTRACT: The Palmer Long Term Ecological Research study region west of the Antarctic Peninsula is experiencing warming and changing seasonal sea ice dynamics. Abundance patterns of 3 species of pelagic secondary producers were analyzed for trends, cycles, range extensions or shifts in the location of highest density, and for changes in population dynamics over a 16 yr period (1993−2008). Species analyzed represented different hydrographic regimes and are known to have contrasting responses to seasonal sea ice dynamics: krill Euphausia superba, seasonal sea ice zone; tunicates Salpa thompsoni, warmer waters with minimal sea ice; and larval Antarctic silverfish Pleuragramma antarcticum, cold continental shelf waters. Cycles were observed in grid-wide abundance and recruitment for E. superba. Maximum grid-wide densities did not decrease, but the location of highest densities shifted southward 200 km, away from Adélie penguin rookeries at the northern end. A distinct change post-1999 was apparent in the frequency of occurrence and abundance of S. thompsoni. Mixtures of krill and salps became common, but neither peak densities nor the frequency of peak years for salps increased. As with Antarctic krill, highest salp densities shifted southward alongshore. Larval P. antarcticum were abundant in the northern coastal region in the early 1990s, but virtually disappeared in that region after 1999/2000. Possible mechanisms underlying these observations include the southerly movement of the sea ice edge during spring, changes in proximity of source populations (salps), and changes in transport pathways (larval P. antarcticum). Patterns are compared to those in the SW Atlantic.
Group B Streptococcus (GBS) is the leading cause of bacterial sepsis and meningitis among neonate... more Group B Streptococcus (GBS) is the leading cause of bacterial sepsis and meningitis among neonates. While the capsular polysaccharide (CPS) is an important virulence factor of GBS, other cell surface components, such as C proteins, may also play a role in GBS disease. CPS production by GBS type III strain M781 was greater when cells were held at a fast (1.4-h mass-doubling time [td]) than at a slow (11-h td) rate of growth. To further investigate growth rate regulation of CPS production and to investigate production of other cell components, different serotypes and strains of GBS were grown in continuous culture in a semidefined and a complex medium. Samples were obtained after at least five generations at the selected growth rate. Cells and cell-free supernatants were processed immediately, and results from all assays were normalized for cell dry weight. All serotypes (Ia, Ib, and III) and strains (one or two strains per serotype) tested produced at least 3.6-fold more CPS at a td ...
The capsular polysaccharide (CPS) of group B streptococci (GBS) is an important virulence factor ... more The capsular polysaccharide (CPS) of group B streptococci (GBS) is an important virulence factor that also serves to protect cells from nonspecific host defense mechanisms. Expression of CPS by GBS, as with other encapsulated bacterial pathogens, is not constitutive but varies during growth in vitro and in primary cultures isolated from different sites of infection. Despite this understanding, little is known about regulation of this surface-expressed carbohydrate antigen in GBS. Here we report that expression of type III CPS by GBS strain M781 grown in continuous culture with a modified chemically defined medium is regulated by growth rate. Cells in steady state at mass doubling times (tds) of 0.8, 1.4, and 1.6 h expressed an average of sixfold more cell-associated CPS than did cells held at tds of 2.3 and 11 h. Strain M781 grown at a td of 1.4 h repeatedly produced more type III CPS than those held at a td of 11.0 h, even when limited for glucose, pyridoxamine, or thiamine. In our...
Three statistical models that predict microbial interactions within the vaginal environment are p... more Three statistical models that predict microbial interactions within the vaginal environment are presented. A large data set was assembled from in vivo studies describing the healthy vaginal environment, and the data set was analyzed to determine whether statistical models which would accurately predict the interactions of the microflora in this environment could be formulated. During assembly of the data set, two new variables were defined and were added to the data set, that is, cycle (sequence of menstrual cycle) and flow stage (subdivision of cycle determined by day of menstrual cycle). Concentrations of total aerobic (includes facultative) bacteria, total anaerobic bacteria, and a Corynebacterium sp. were identified by correlation analysis as variables with significant predictors. By using a regression method with a backward elimination procedure, significant predictors of these outcome variables were identified as the concentrations of Lactobacillus spp., anaerobic Streptococcu...
In this study we identified subgroups of observations relating to the healthy vaginal microbiota.... more In this study we identified subgroups of observations relating to the healthy vaginal microbiota. This microbiota resides in a dynamic environment that undergoes cyclic change during the menstrual cycle. Cluster analysis procedures were applied to divide a set of 226 normal microbiota observations into groups. Three subgroups containing 100, 65, and 61 observations were identified. Plots of principal components determined by canonical analysis were obtained to demonstrate graphically the clustering of normal vaginal microbiota observations into subgroups. Results from the cluster analyses were verified using a predictive logit regression model. Analysis of mean logit values for the three clusters demonstrated that they differed from each other. Further verification was obtained using data from women with abnormal vaginal microbiota, either due to a yeast infection or the use of an iodine-based medicated douche product, and applying them to the clustering results developed using the ...
Herein we report studies with a novel combination vaccine that, when administered to mice, confer... more Herein we report studies with a novel combination vaccine that, when administered to mice, conferred protection against highly virulent strains of Francisella tularensis by stimulating both arms of the immune system. Our earlier studies with Ft.LVS::wbtA, an O-polysaccharide (OPS)-negative mutant derived from the available live vaccine strain of F. tularensis (Ft.LVS), elucidated the role of antibodies to the OPS - a key virulence determinant - in protection against virulent type A organisms. However, when expressed on the organism, the OPS enhances virulence. In contrast, in purified form, the OPS is completely benign. We hypothesized that a novel combination vaccine containing both a component that induces humoral immunity and a component that induces cellular immunity to this intracellular microbe would have an enhanced protective capacity over either component alone and would be much safer than the LVS vaccine. Thus we developed a combination vaccine containing both OPS (supplie...
Page 1. Phycologia (1995) Volume 34 (5), 424-430 Vertical distribution of Antarctic peninsular ma... more Page 1. Phycologia (1995) Volume 34 (5), 424-430 Vertical distribution of Antarctic peninsular macroalgae: cover, biomass and species composition* CHARLES D. AMSLER!, ROBERT J. ROWLEy2, DAVID R. LAUR2, LANGDON B. QUETIN2 AND ROBIN M. Ross2 ...
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