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Biology

Selected Works

1995

Articles 1 - 10 of 10

Full-Text Articles in Life Sciences

Use Of Elisa For Determination Of Plasma Prolactin Levels In The House Wren, Given Harper, Sharon M. Sintich, Michelle K. Keagle, Ian G. Welsford Oct 1995

Use Of Elisa For Determination Of Plasma Prolactin Levels In The House Wren, Given Harper, Sharon M. Sintich, Michelle K. Keagle, Ian G. Welsford

Given Harper

Prolactin concentrations in avian plasma have been traditionally quantified using a radioimmunoassay (RIA) procedure. RIA is useful for such studies due to its sensitivity and specificity (e.g., Follett et al. 1972, Wingfield and Farner 1975, McNeilly et al. 1978, Burke and Papkoff 1980, Schwabl 1993). For example, the heterologous RIA for detecting prolactin in turkeys, developed by McNeilly et al. (1978), recovered 98% of a prolactin standard added to a turkey plasma sample and exhibited less than 0.1% cross reactivity with other plasma hormones. In an homologous RIA developed by Burke and Papkoff (1980), detection limits of approximately 0.42 ± …

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A Second Nitrogenase In Vegetative Cells Of A Heterocyst-Forming Cyanobacterium, T Thiel, E M. Lyons, J C. Erker, A Ernst Sep 1995

A Second Nitrogenase In Vegetative Cells Of A Heterocyst-Forming Cyanobacterium, T Thiel, E M. Lyons, J C. Erker, A Ernst

Teresa Thiel

In many filamentous cyanobacteria nitrogen fixation occurs in differentiated cells called heterocysts. Filamentous strains that do not form heterocysts may fix nitrogen in vegetative cells, primarily under anaerobic conditions. We describe here two functional Mo-dependent nitrogenases in a single organism, the cyanobacterium Anabaena variabilis. Using a lacZ reporter with a fluorescent beta-galactoside substrate for in situ localization of gene expression, we have shown that the two clusters of nif genes are expressed independently. One nitrogenase functions only in heterocysts under either aerobic or anaerobic growth conditions, whereas the second nitrogenase functions only under anaerobic conditions in vegetative cells and heterocysts. …

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The Inductive Role Of Bacterial Symbionts In The Morphogenesis Of A Squid Light Organ., Mary Montgomery, M Mcfall-Ngai Aug 1995

The Inductive Role Of Bacterial Symbionts In The Morphogenesis Of A Squid Light Organ., Mary Montgomery, M Mcfall-Ngai

Mary Montgomery

No abstract provided.

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Isolation And Analysis Of Nephritic-Producing Immune Complexes In Plasmodium Berghei-Infected Mice, Clarence Lee, Eric J. Toran Aug 1995

Isolation And Analysis Of Nephritic-Producing Immune Complexes In Plasmodium Berghei-Infected Mice, Clarence Lee, Eric J. Toran

Clarence Lee

A nephritic condition was developed by infecting Swiss Webster albino mice with the malarial parasite Plasmodium berghei NK 65. These animals were tested for urinary protein and the presence of circulating immune complexes using reagent strips and a polyethylene glycol (PEG) precipitation assay. The circulating immune complexes were isolated from the sera using both affinity chromatography and PEG precipitation and from the kidney by acid elution. The isolated complexes were dissociated into their individual components and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The components of the complexes were transferred to nitrocellulose sheets and probed for the presence of …

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The Comparative Metabolism Of The Four Pyrrolizidine Alkaloids, Seneciphylline, Retrorsine, Monocrotaline, And Trichodesmine In The Isolated, Perfused Rat Liver., C. C. Yan, R. A. Cooper, R. J. Huxtable Jul 1995

The Comparative Metabolism Of The Four Pyrrolizidine Alkaloids, Seneciphylline, Retrorsine, Monocrotaline, And Trichodesmine In The Isolated, Perfused Rat Liver., C. C. Yan, R. A. Cooper, R. J. Huxtable

Roland A. Cooper

Despite their similarity in structure, pyrrolizidine alkaloids (PAs) vary in their LD50s and in the organs in which toxicity is expressed. We have examined whether there are differences in the metabolism of certain PAs that are associated with these quantitative and qualitative differences in toxicity. Isolated rat livers were perfused with one of four PAs (seneciphylline, retrorsine, monocrotaline, and trichodesmine) at 0.5 mM for 1 hr, and the pyrrolic metabolites determined that were released into perfusate and bile or bound in the liver. The proportion of the PA removed by the liver varied from 93% for retrorsine to 55% for …

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Pollination Of The Crown Imperial Fritillaria Imperialis By Great Tits Parus Major, Winfried S. Peters, Michael Pirl, Gerhard Gottsberger, Dieter Stefan Peters Feb 1995

Pollination Of The Crown Imperial Fritillaria Imperialis By Great Tits Parus Major, Winfried S. Peters, Michael Pirl, Gerhard Gottsberger, Dieter Stefan Peters

Winfried S. Peters

Visitations of flowers of the Crown Imperial by Great Tits at two different locations in Hessen, Germany, in 1990 and 1993 are described. The observations prove that flowers were visited because of the nectar; most likely pollination occurs during this visits. Similar reports from Europe are discussed. The significance of specific interactions including ecological generalists such as the Great Tit is considered in the context of the phylogenetic reconstruction of the development of co-adaptive syndroms.

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Geographic And Host Species Effects In Eurosta Solidaginis (Diptera: Tephritidae) Mortality, D. Sumerford, W. Abrahamson Dec 1994

Geographic And Host Species Effects In Eurosta Solidaginis (Diptera: Tephritidae) Mortality, D. Sumerford, W. Abrahamson

Warren G. Abrahamson, II

No abstract provided.

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Spontaneous Mutation During The Sexual Cycle Of Neurospora Crassa, Michael Watters, David Stadler Dec 1994

Spontaneous Mutation During The Sexual Cycle Of Neurospora Crassa, Michael Watters, David Stadler

Michael Watters

The DNA sequences of 42 spontaneous mutations of the mtr gene in Neurospora crassa have been determined. The mutantws ere selected among sexual spores to represent mutations arising in the sexual cycle. Three sexualcycle-specific mutational classes are described: hotspot mutants, spontaneous repeatinduced point mutation (RIPS) and mutations occurring during a mutagenic phase of the sexual cycle. Together, these three sexual-cycle-specific mutational classes account fo5r0 % of the mutations in the sexual-cycle mutational spectrum. One thiordf all mutations occurred at onoef two mutational hotspots that predominantly produced tandem duplications of varying lengths with short repeats at their endpoints. Neither of the …

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Hydraulic Conductivity Of Concentric Root Tissues Of Agave Deserti Englem. Under Wet And Drying Conditions, Gretchen North, P. Nobel Dec 1994

Hydraulic Conductivity Of Concentric Root Tissues Of Agave Deserti Englem. Under Wet And Drying Conditions, Gretchen North, P. Nobel

Gretchen North

Water moves from the root surface to the root xylem through a series of tissues, each with properties that influence the root radial hydraulic conductivity (LR). To determine LR for intact roots, root hydraulic conductivity (LP) and axial (xylem) conductance (Kh) were measured for root segments of the desert succulent Agave deserti Engelm. As layers were successively removed, LR was calculated for each layer by considering the conductivities in series. For the distal root region, no single tissue limited LR under wet conditions, although the suberized exodermis and sclerenchyma/endodermis were more limiting per cross-sectional area of the root than were …

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A Beta-Linked Mannan Inhibits Adherence Of Pseudomonas Aeruginosa To Human Lung Epithelial Cells, Ali Azghani, Izola Williams, David B. Holiday, Alice R. Johnson Dec 1994

A Beta-Linked Mannan Inhibits Adherence Of Pseudomonas Aeruginosa To Human Lung Epithelial Cells, Ali Azghani, Izola Williams, David B. Holiday, Alice R. Johnson

Ali Azghani

Adherence through carbohydrate-binding adhesins is an early step in colonization of the lung by gram-negative organisms, and because published data indicate that binding involves mannose groups, we tested the ability of a β-linked acetylmannan (acemannan) to inhibit adherence of Pseudomonus aeruginosa to cultures of human lung epithelial cells. Adherence of radiolabelled P.aeruginosa to A549 cells (a type II-like pneurnocyte line) increased linearly with the duration of the incubation. Acemannan inhibited adherence of bacteria, and the extent of inhibition was related to the concentration of the mannan. Inhibition required continued contact between acemannan and the target epithelial cells; cells washed free …

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