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1989

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Articles 1 - 30 of 42

Full-Text Articles in Life Sciences

Heterochronic Genes Control The Stage-Specific Initiation And Expression Of The Dauer Larva Developmental Program In Caenorhabditis Elegans, Zhongchi Liu, Victor R. Ambros Nov 1989

Heterochronic Genes Control The Stage-Specific Initiation And Expression Of The Dauer Larva Developmental Program In Caenorhabditis Elegans, Zhongchi Liu, Victor R. Ambros

Victor R. Ambros

We report that a stage-specific developmental program, dauer larva formation, is temporally regulated by four heterochronic genes, lin-4, lin-14, lin-28, and lin-29. The effects of mutations in these four genes on dauer larva formation have revealed that they regulate two different processes of dauer larva formation: (1) a decision specifying the larval stage at which dauer larva development initiates, and (2) the specialized differentiation of hypodermal cells during dauer larva morphogenesis. Epistasis analysis has suggested a model in which lin-4 negatively regulates lin-14, and the resulting temporal decrease in lin-14 activity specifies the stage of dauer larva initiation. Our results …

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Presence Of A Cs-Resistant Transient Outward Current Which Distorts Ica Measurements In Guinea-Pig Single Ventricular Cells, Georges Christé, Brigitte Delachapelle, Fouad Lemtiri-Chlieh, Carlos Ojeda Nov 1989

Presence Of A Cs-Resistant Transient Outward Current Which Distorts Ica Measurements In Guinea-Pig Single Ventricular Cells, Georges Christé, Brigitte Delachapelle, Fouad Lemtiri-Chlieh, Carlos Ojeda

fouad Lemtiri-Chlieh

To correctlyr analyse the physical properties of ion channels and the actions of drugs upon them, it is important that the membrane conducts only the ionic species believed permeant. In guinea-pig ventricular cells it has been assumed that only ICaL flows in the potential range -50 to +60 mV in the presence of intra- and extracellular Cs (> 20 mM). We report here that this is not the case due to the presence of a Cs-insensitive, transient outward current.

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Measurements Of Cytosolic Free Ca In Cultured Rat Neonate And Adult Guinea-Pig Ventricular Cardiac Myocytes, Jean-Claude Bernengo, Fouad Lemtiri-Chlieh, Carlos Ojeda, Nadine Pltonoff Nov 1989

Measurements Of Cytosolic Free Ca In Cultured Rat Neonate And Adult Guinea-Pig Ventricular Cardiac Myocytes, Jean-Claude Bernengo, Fouad Lemtiri-Chlieh, Carlos Ojeda, Nadine Pltonoff

fouad Lemtiri-Chlieh

Cytosolic free Ca was measured with Indo-1 (Grynkiewicz et al. 1985) as free acid (in guinea-pig cells) or as the ester (in rat neonate cells). Using image analysis we obtained concentration maps at 40 ms intervals at two wavelengths (Cannell et al. 1986). In rat neonate cells, at rest and during contraction, calcium was apparently non-uniformly distributed, in contrast to guinea-pig adult cells. Using a dual PM spectroscopic system adapted to an inverted microscope we found: (1) the conversion of Indo-AM to Indo- 1 in the cytosol is not complete (< 40% contribution to the total light); (2) rat neonate cells buffer Ca (at rest 130-170 nM) only for [Ca]. between 1 and 3 mM, whereas in adult guinea-pig cells the range extended to 10 mM; (3) during contraction [Ca]i rose from 200 nm to no more than 1 microM. Digitoxin increases basal and peak [Ca]i; (4) during spontaneous contractions, in guinea-pig cells, [Ca]i rises from 70 to 200 nm when [Ca]o = 0, and from 170 nm to about 1 microM when [Ca]o = 2 mM; (5) in voltage-clamp conditions the rise in [Ca]i does not exceed 2 microM and oscillations occur in the presence of forskolin. When loading with Indo-1, cells frequently cease to contract (Powell et al. 1988) and the variations in [Ca]i are then very small (about 200 nm at peak ICa). In both cases these values are small compared to the total charge crossing the membrane.

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Pig Vocalizations Under Selected Husbandry Practices, Hongwei Xin, James A. Deshazer, D. W. Leger Nov 1989

Pig Vocalizations Under Selected Husbandry Practices, Hongwei Xin, James A. Deshazer, D. W. Leger

Hongwei Xin

Acoustical characteristics of vocalizations of sows, piglets, and nursery pigs under selected husbandry practices were analyzed with a digital signal processing system. The duration (D) and major energy-resonance frequency (P) for each call were determined as follows: a) processing of piglets (D = 0.81 s and f* = 3 700 Hz); b) food anticipation of breeding-gestation sows (2.50 s and 3 000 Hz); c) isolation of piglet (0.34 s and 500, 3 500 Hz); d) startling of nursery pigs (0.29 s and 900 Hz); e) sows in heat (3.07 s and 1 375 Hz); f) farrowing (0.10 s and 3 …

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The Effects Of Site Quality On Breeding-Site Fidelity In Bobolinks, Eric K. Bollinger, Thomas A. Gavin Oct 1989

The Effects Of Site Quality On Breeding-Site Fidelity In Bobolinks, Eric K. Bollinger, Thomas A. Gavin

Eric K. Bollinger

We compared breeding-site fidelity of Bobolinks (Dolichonyx oryzivorus) at two low-quality sites (Bald Hill and Shackelton Point, BH +SP) with that at one high-quality site (Moore Road, MR) in central New York. Yearly density of fledglings at Moore Road was more than six times the density at Bald Hill and Shackelton Point. Furthermore, individual residents fledged 50-70% more young at the high-quality site. At Moore Road, 70% of the males and 49% of the females returned one or more times, compared with 44% of the males and 25% of the females at the low-quality sites. Successful residents (i.e. those fledging …

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Isolation And Partial Characterization Of The Glutamate/Aspartate Transporter From Pea Leaf Mitochondria Using A Specific Monoclonal Antibody, Jeevalatha Vivekananda, David J. Oliver Sep 1989

Isolation And Partial Characterization Of The Glutamate/Aspartate Transporter From Pea Leaf Mitochondria Using A Specific Monoclonal Antibody, Jeevalatha Vivekananda, David J. Oliver

David J. Oliver

A library of monoclonal antibodies directed against the proteins of the inner mitochondrial membrane was screened for antibodies that could bind to the glutamate/aspartate transporter of pea mitochondria and thereby inhibit its activity. One antibody, 2C7, had the property of inhibiting glutamate and aspartate-dependent oxaloacetate metabolism by pea mitochondria without affecting the metabolism of other substrates. The antibody specifically recognized a 21,000 dalton protein, which was tentatively identified as the glutamate/aspartate transporter. The antibody was used to follow the extraction of this protein by Triton X-114 and cardiolipin and the partial purification of the protein by centrifugation and chromatography on …

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Toxicology Of Synthetic Pyrethroids In Aquatic Organisms: An Overview, Steven P. Bradbury, Joel R. Coats, D. M. Symonik, S. D. Dyer, L. K. Timson, G. J. Atchison Aug 1989

Toxicology Of Synthetic Pyrethroids In Aquatic Organisms: An Overview, Steven P. Bradbury, Joel R. Coats, D. M. Symonik, S. D. Dyer, L. K. Timson, G. J. Atchison

Steven P. Bradbury

The aquatic toxicology of the photostable synthetic pyrethroid insecticides as it affects two important groups of susceptible organisms — fish and aquatic insects — is discussed. The sensitivity of these aquatic species to the pyrethroids is dependent on several factors, including toxicokinetics, target site (nervous system), sensitivity and possible secondary mechanisms of action, as well as chemical and physical properties of the aquatic medium that influence toxicity and bioavailability. Uptake rates and routes of fenvalerate greatly affected the toxicity of fenvalerate to mosquito larvae. LD50 values were determined for cuticular and dietary exposure routes by utilizing radiolabeled fenvalerate at the …

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Amino Acid Uptake And Metabolism By Larvae Of The Marine Worm Urechis Caupo (Echiura), A New Species In Axenic Culture, William Jaeckle, Donal T. Manahan May 1989

Amino Acid Uptake And Metabolism By Larvae Of The Marine Worm Urechis Caupo (Echiura), A New Species In Axenic Culture, William Jaeckle, Donal T. Manahan

William Jaeckle

Axenic (bacteria-free) larval cultures of the marine echiuran worm, Urechis caupo, were reliably obtained by aseptically removing gametes directly from the gamete storage organs. Trochophore larvae only removed neutral amino acids from seawater as measured by high-performance liquid chromatography (HPLC). There was no detectable uptake, as measured by HPLC, of acidic or basic amino acids. Kinetic analysis showed that the transport system for alanine in 4-day-old larvae had a Kt of 4-6 μM and a Jmax of 9-10 pmol larva-1 h-1. Following a 50-min exposure, the majority of the radio-activity (95%) from 14C-alanine was found in the trichlo-roacetic acid-soluble fraction. …

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Toxicokinetics And Toxicodynamics Of Pyrethroid Insecticides In Fish, Steven P. Bradbury, Joel R. Coats May 1989

Toxicokinetics And Toxicodynamics Of Pyrethroid Insecticides In Fish, Steven P. Bradbury, Joel R. Coats

Steven P. Bradbury

The pyrethroid insecticides are extremely toxic to fish, with 96—h LC50 values generally below 10 μg/L and i.p. and i.v. LD50 values below 20 mg/kg. Corresponding LD50 values in mammals and birds are in the range of several hundred to several thousand milligrams per kilogram. This review examines pyrethroid toxicokinetics and toxicodynamics in fish as critical factors associated with species selectivity. Studies with permethrin, cypermethrin and fenvalerate have established that rates of metabolism and elimination in rainbow trout are significantly lower than those reported for birds and mammals. Comparatively low lethal brain pyrethroid concentrations and nonneural aspects of pyrethroid intoxication …

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Use Of Respiratory-Cardiovascular Responses Of Rainbow Trout (Salmo Gairdneri) In Identifying Acute Toxicity Syndromes In Fish: Part 3. Polar Narcotics, Steven P. Bradbury, Tala R. Henry, Gerald J. Niemi, Richard W. Carlson, Virginia M. Snarski Mar 1989

Use Of Respiratory-Cardiovascular Responses Of Rainbow Trout (Salmo Gairdneri) In Identifying Acute Toxicity Syndromes In Fish: Part 3. Polar Narcotics, Steven P. Bradbury, Tala R. Henry, Gerald J. Niemi, Richard W. Carlson, Virginia M. Snarski

Steven P. Bradbury

The physiological responses of rainbow trout to acutely lethal aqueous concentrations of the suspected polar narcotics phenol, 2,4-dimethylphenol, aniline, 2-chloroaniline and 4-chloroaniline were examined. Visible signs of intoxication included tremors that progressed to whole-organism clonic seizures, followed by general depression and respiratory-cardiovascular collapse. Tremors and seizures were usually initiated with coughs. The most striking changes in the respiratory-cardiovascular parameters for all five toxicants included elevated cough frequency (coincident with seizures), ventilation frequency and hematocrit, and depressed gill oxygen uptake efficiency, arterial pH, total arterial oxygen and total arterial carbon dioxide. The physiological responses noted were attributed to the initial muscular …

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Regulation Of Pheromone Biosynthesis By A Brain Hormone In Two Moth Species, Juliet D. Tang, Ralph E. Charlton, Russell A. Jurenka, Walter A. Wolf, P. Larry Phelan, Leam Sreng, Wendell L. Roelofs Mar 1989

Regulation Of Pheromone Biosynthesis By A Brain Hormone In Two Moth Species, Juliet D. Tang, Ralph E. Charlton, Russell A. Jurenka, Walter A. Wolf, P. Larry Phelan, Leam Sreng, Wendell L. Roelofs

Russell A. Jurenka

Experiments were performed to characterize the action of a brain hormone on pheromone biosynthesis in female redbanded leafroller and cabbage looper moths. Results showed that the two species differed in their respective control mechanisms. In the cabbage looper, pheromone titer from decapitated females that received either saline or brain extract injections was not significantly different from control females, suggesting that pheromone biosynthesis was not dependent on the presence of the brain hormone. In contrast, with redbanded leafroller females, studies using radiolabeled acetate incorporation as well as incorporation of deuterium-labeled hexadecanoic acid showed that (i) the brain hormone was required for …

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Attachment And Proliferation Of Bacteria On Meat, James S. Dickson, King-Thom Chung, John D. Crouse Mar 1989

Attachment And Proliferation Of Bacteria On Meat, James S. Dickson, King-Thom Chung, John D. Crouse

James S. Dickson

The attachment of bacteria (Serratia marcescens, Staphylococcus aureus, Streptococcus faecalis, Salmonella arizonae, Pseudomonas aeruginosa, and Listeria monocytogenes), to lean muscle tissue and fat tissue was investigated. The number of cells attached to the meat was directly proportional to the initial cell concentrations present. There was no significant difference in the number of cells attached between the lean muscle tissue and fat tissues among the organisms tested. All bacteria tested except P. aeruginosa proliferated better on the lean muscle tissues than on the fat tissue at ambient temperature for 72 h. No significant attachment competition to tissue samples was seen between …

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Utah Coordinated Resource Management And Planning Handbook And Guidelines, Roger E. Banner, Milo A. Barney, Curtis M. Johnson, R. Dean Harrison, Jens C. Jensen Jan 1989

Utah Coordinated Resource Management And Planning Handbook And Guidelines, Roger E. Banner, Milo A. Barney, Curtis M. Johnson, R. Dean Harrison, Jens C. Jensen

Roger E. Banner

No abstract provided.

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Genetic Variability Within And Among Wintering Populations Of Brant, James M. Novak, L. M. Smith, L. D. Vangilder Jan 1989

Genetic Variability Within And Among Wintering Populations Of Brant, James M. Novak, L. M. Smith, L. D. Vangilder

James M. Novak

No abstract provided.

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The Genera Of Commelinaceae In The Southeastern United States, Gordon C. Tucker Jan 1989

The Genera Of Commelinaceae In The Southeastern United States, Gordon C. Tucker

Gordon C. Tucker

No abstract provided.

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Ontogenic Changes In The Rates Of Amino Acid Transport From Seawater By Marine Invertebrate Larvae (Echinodermata, Echiura, Mollusca), Donal Manahan, William Jaeckle, Saeid Nourizadeh Jan 1989

Ontogenic Changes In The Rates Of Amino Acid Transport From Seawater By Marine Invertebrate Larvae (Echinodermata, Echiura, Mollusca), Donal Manahan, William Jaeckle, Saeid Nourizadeh

William Jaeckle

Transport rates of amino acids were determined for larvae of different ages of the echiuran worm Urechis caupo, the gastropod Haliotis rufescens, the bivalve Crassostrea gigas, and the sea urchin Strongylocentrotus purpuratus. All larval forms showed an increase in the transport rate of amino acids during development. Trochophores of U. caupo increased their rate of net flux for each of 5 amino acids (100 nM each) by a factor of 1.6 and 2.2 during 1-3 days and 4-8 days, respectively, for two independent cultures. In H. rufescens, the maximum transport capacity (Jmax) for alanine increased 3-fold during the 24 h …

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Phosphorus Fertilization Through Drip Irrigation, Robert Mikkelsen Jan 1989

Phosphorus Fertilization Through Drip Irrigation, Robert Mikkelsen

Robert Mikkelsen

Although P fertilization through drip irrigation systems has not been widely recommended, a review of currently available literature indicates this fertilizer application technique can offer many advantages when performed properly. Using drip irrigation to apply P fertilizer allows nutrient placement directly into the plant root zone during critical periods of nutrient demand. Less P fertilizer is generally required to achieve sufficient tissue P concentrations and equivalent yields when it is drip-applied than with other application methods. The distribution of drip-applied P in soil depends on soil properties, the source of P fertilizer, the rate of application, and the amount of …

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Factors Affecting Selenium Accumulation By Agricultural Crops, Robert Mikkelsen, Albert L. Page, Frank T. Bingham Jan 1989

Factors Affecting Selenium Accumulation By Agricultural Crops, Robert Mikkelsen, Albert L. Page, Frank T. Bingham

Robert Mikkelsen

The accumulation of selenium by plants is of concern worldwide. Many regions grow crops that contain insufficient Se to meet animal nutritional requirements. In these locations with low Se, efforts have been made to increase tissue Se concentrations. Other areas have problems with excessive Se found in vegetation grown on seleniferous soils. Plant species vary in their ability to accumulate and tolerate Se. Selenium accumulator plants can accumulate extremely high Se concentrations (several thousand mg Se kg-1) when grown in seleniferous soils, whereas typical agricultural crops have a much lower Se tolerance (<50 mg Se kg>-1 ). It has been suggested that …

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Genetics Of Screwworm, New Genetic Markers And Preliminary Linkage Map., David B. Taylor Jan 1989

Genetics Of Screwworm, New Genetic Markers And Preliminary Linkage Map., David B. Taylor

David B Taylor

Eight new genetic markers for Cochliomyia hominivorax (Diptera: Calliphoridae), the screwworm, are characterized. The markers include three eye mutants, lemon-eye (le), cherry-eye (ch), and red-eye (re); one wing mutant, curly-wing (cw); and four allozyme markers, amylase (Amy-1), glycerol-3-phosphate dehydrogenase (Gpd), phosphoglucomutase (Pgm), and octanol dehydrogenase (Odh). The markers are associated into four linkage groups. Radiation-induced translocations were used to correlate the linkage groups with their respective chromosomes. A preliminary genetic linkage map with these and three previously characterized loci is presented.

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Polar Narcosis In Aquatic Organisms, Steven P. Bradbury, Richard W. Carlson, Tala R. Henry Jan 1989

Polar Narcosis In Aquatic Organisms, Steven P. Bradbury, Richard W. Carlson, Tala R. Henry

Steven P. Bradbury

The majority of industrial organic chemicals lack identifiable structural characteristics that result in specific biological activity. These nonpolar-nonelectrolytes are acutely toxic to aquatic organisms via a nonspecific mode of action termed narcosis. The toxicity of industrial chemicals eliciting nonpolar narcosis can be reliably predicted by log P (baseline toxicity models). Using single chemical and joint toxic action models, several research groups have reported classes of polar compounds (for example, esters, phenols, and anilines) that elicit a narcosis-like syndrome; however, they are more acutely toxic than what is predicted using baseline toxicity models. An assessment of rainbow trout (Salmo gairdneri) in …

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Comparative Toxicology Of The Pyrethroid Insecticides, Steven P. Bradbury, Joel R. Coats Jan 1989

Comparative Toxicology Of The Pyrethroid Insecticides, Steven P. Bradbury, Joel R. Coats

Steven P. Bradbury

The toxic effects elicited by synthetic pyrethroids in animals are varied in degree and nature. Their relative safety to birds and mammals contrasts sharply with their acute effects on fish and arthropods. Explantation of their differences in toxicity depends on examination of all factors of their comparative toxicology. Routes of exposure are important, as are metabolism and elimination rates, especially for mammals and birds with their considerable capabilities for biotransformation. Significant differences in sensitivity at the sites of toxic action may also play a role in differential responses to these insecticides. Finally, physical properties that influence the environmental disposition and …

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Separation Of Turkey Heterophils From Blood Using Two-Step Ficoll-Hypaque Discontinuous Gradients, Kenneth S. Latimer, Ingrid M. Kircher, Claire B. Andreasen Jan 1989

Separation Of Turkey Heterophils From Blood Using Two-Step Ficoll-Hypaque Discontinuous Gradients, Kenneth S. Latimer, Ingrid M. Kircher, Claire B. Andreasen

Claire B. Andreasen

A method is presented to separate turkey heterophils from anticoagulated whole blood using two-step Ficoll-Hypaque discontinuous gradients and ammonium chloride lysis of contaminating erythrocytes. Heterophils can be isolated from multiple blood samples within 3 to 4 hours. Using this technique, 66.4 +- 18.4% (mean +- standard deviation) of blood heterophils were harvested. Final cell isolates averaged 96.0 +- 2.9% heterophils with few contaminating eosinophils (2.5 +- 2.3%) or basophils (1.6 +- 1.8%). Cell viability, as determined by trypan blue dye exclusion, was 98.0 +- 1.4%.

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An Electrochemical Method Of Measuring The Oxidation Rate Of Ferrous To Ferric Iron With Oxygen In The Presence Of Thiobacillus Ferrooxidans, David J. Oliver, B. Pesic, P. Wichlacz Jan 1989

An Electrochemical Method Of Measuring The Oxidation Rate Of Ferrous To Ferric Iron With Oxygen In The Presence Of Thiobacillus Ferrooxidans, David J. Oliver, B. Pesic, P. Wichlacz

David J. Oliver

The oxidation of Fe2+ with oxygen in sulfate solutions was studied in the presence of T. ferrooxidans. To measure the chemical activity of bacteria, and the oxidation rate of iron, the redox potentials of solutions were continuously monitored during the experiments. The redox potentials were simultaneously monitored on the platinum and pyrite indicator electrodes. The redox potential versus time curves were further used to calculate the basic kinetic parameters, such as the reaction orders, the activation energy, and the frequency factor. It was found that under atmospheric conditions, and at Fe2+ < 0.001M, T < 25°C, and at pH above 2.2, the oxidation of iron is governed by the following rate expression: [equation image] Below pH = 2.2, the oxidation rate is independent of H+ Concentration.

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Separation Of Avian Heterophils From Blood Using Ficoll-Hypaque Discontinuous Gradients, Claire B. Andreasen, Kenneth S. Latimer Jan 1989

Separation Of Avian Heterophils From Blood Using Ficoll-Hypaque Discontinuous Gradients, Claire B. Andreasen, Kenneth S. Latimer

Claire B. Andreasen

Rapid separation of avian heterophils from anticoagulated whole blood was achieved using Ficoll-Hypaque discontinuous gradients. An average of 14.4% of blood heterophils was harvested with a mean purity exceeding 99%. Heterophil viability, as determined by trypan blue dye exclusion, averaged 99.8%. The integrity of isolated heterophils was evaluated by cytochemical staining and ultrastructural examination. Cytochemical staining reactions of heterophils in whole blood and of isolated cell suspensions were similar. No ultrastructural abnormalities were observed. Using this procedure, viable intact heterophils were rapidly isolated from blood with an acceptable cell yield and purity for cell function studies.

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Sheep Preference For Perennial Glandular-Haired And Eglandular Medicago Populations, Andrew W. Lenssen, E. L. Sorensen, G. L. Posler, L. H. Harbers Jan 1989

Sheep Preference For Perennial Glandular-Haired And Eglandular Medicago Populations, Andrew W. Lenssen, E. L. Sorensen, G. L. Posler, L. H. Harbers

Andrew W. Lenssen

Erect glandular-haired Medicago species and hybrid populations have been developed that possess a high degree of resistance to the alfalfa weevil [Hypera postica (Gyllenhal)] and potato leafhopper [Empoasca fabae (Harris)]. Trials were conducted at the North Agronomy Farm, Manhattan, KS, in June and August 1986 to determine if erect glandular hairs on diverse perennial Medicago populations affect forage preference of sheep (Ovis aries). Glandular-haired (+) and eglandular (−) populations were selected from each of the following: diploids M. prostrata Jacq. and M. glandulosa David (KS94) and tetraploids M. glutinosa Bieb. (KS108), M. sativa L. ✕ M. prostrata (KS159), and M. …

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A Comparison Of Magnetite Particles Produced Anaerobically By Magnetotactic And Dissimilatory Iron-Reducing Acteria, Derek Lovley, Bruce M. Moskowitz, Richard B. Frankel, Dennis A. Bazylinski, Holger W. Jannasch Jan 1989

A Comparison Of Magnetite Particles Produced Anaerobically By Magnetotactic And Dissimilatory Iron-Reducing Acteria, Derek Lovley, Bruce M. Moskowitz, Richard B. Frankel, Dennis A. Bazylinski, Holger W. Jannasch

Derek Lovley

No abstract provided.

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Comparative Response Of Swine And Rats To High Fiber Or High Protein Diets, James S. Dickson Jan 1989

Comparative Response Of Swine And Rats To High Fiber Or High Protein Diets, James S. Dickson

James S. Dickson

Twenty-four growing swine and 24 growing rats were fed high-protein (34%) diets on an ad libimm basis to determine their effects on body weight, carcass characteristics, intestinal microbiological profile and visceral organ weights. High dietary fiber reduced body weight gain and gain:feed ratio in both swine and rats and decreased body famess in swine; it increased relative kidney weight (percentage of body weight) in both swine and rats and decreased relative liver weight in rats but increased it in swine. Absolute weights of stomach and large intestine were unaffected by high fiber in either species, but relative weight of small …

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Effect Of Electrical Charge On Attachment Of Salmonella Typhimurium To Meat Surfaces, James S. Dickson, John D. Crouse Jan 1989

Effect Of Electrical Charge On Attachment Of Salmonella Typhimurium To Meat Surfaces, James S. Dickson, John D. Crouse

James S. Dickson

Treating tissue with electrical current was found to affect both the initial attachment and total numbers of attached Salmonella typhimun’unl to meat tissues. When lean tissue was attached to the positive terminal of the power supply operating at 50 volts/125 mA DC, the total numbero f attachedc ells increasedT. hcrc was no effect when the samples were attached to the negative terminal. There was a significant (PcO.05) effect on the percentage of strongly attached bacteria with an increase in treating time. Electrical current was found to increase the percentage of strongly attached cells immediately after the current was applied.

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Effects Of Nisin On Growth Of Bacteria Attached To Meat, James S. Dickson, K. T. Chung, J. D. Crouse Jan 1989

Effects Of Nisin On Growth Of Bacteria Attached To Meat, James S. Dickson, K. T. Chung, J. D. Crouse

James S. Dickson

Nisin had an inhibitory effect on gram-positive bacteria (Listeria monocytogenes, Staphylococcus aureus, and Streptococcus lactis) but did not have an inhibitory effect on gram-negative bacteria (Serratia marcescens, Salmonella typhimurium, and Pseudomonas aeruginosa) attached to meat. Nisin delayed bacterial growth on meats which were artificially inoculated with L. monocytogenes or Staphylococcus aureus for at least 1 day at room temperature. If the incubation temperature was 5 degrees C, growth of L. monocytogenes was delayed for more than 2 weeks, and growth of Staphylococcus aureus did not occur. We also found that the extractable activity of nisin decreased rapidly when the meats …

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Cell Surface Charge Characteristics And Their Relationship To Bacterial Attachment To Meat Surfaces, James S. Dickson, M. Koohmaraie Jan 1989

Cell Surface Charge Characteristics And Their Relationship To Bacterial Attachment To Meat Surfaces, James S. Dickson, M. Koohmaraie

James S. Dickson

Cell surface charge and hydrophobicity of Bacillus subtilis, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium, Serratia marcescens, Staphylococcus aureus, and Staphylococcus epidermidis were determined by hydrocarbon adherence, hydrophobic interaction, and electrostatic interaction chromatography. Surface charge and hydrophobicity were compared with the initial attachment values and rates of attachment of the bacteria to meat surfaces. There was a linear correlation between the relative negative charge on the bacterial cell surface and initial attachment to lean beef muscle (r2 = 0.885) and fat tissue (r2 = 0.777). Hydrophobicity correlated well with attachment to fat tissue only. The relative hydrophobicity of each bacterium …

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