Mucosal uptake and whole-body retention of dietary manganese are not altered in beta2-microglobulin knockout mice

To further examine the interrelationships between manganese and iron absorption, the mucosal uptake, initial rate of loss, wholebody retention, and tissue distribution of an orally administered ⁵⁴Mn radiotracer were compared between normal and β₂-microglobulin knockout [β₂m(-/-)] mice. These mutant mice are commonly used as a model for the study of human hemochromatosis, a hereditary ironoverload disease. Initial uptake of ⁵⁴Mn by the intestinal mucosa, the liver, and the brain was not different between the two strains. The mutant mice had much higher concentrations of nonheme and total iron in the liver, but hepatic manganese, copper, magnesium, and zinc concentrations were similar between the two strains. In summary, the mucosal uptake and whole-body retention of manganese and tissue manganese concentrations were not altered in β₂m(-/-) mice; this suggests that normal homeostasis of manganese is not affected by the altered HFE protein-β₂m complex in these mice. Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the US Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable. The US Department of Agriculture, Agricultural Research Service, Northern Plains Area, is an equal opportunity/affirmative action employer and all agency services are available without discrimination.     

Magnesium and methionine deprivation affect the response of rats to boron deprivation

A series of nine experiments were done to obtain further evidence that boron might be involved in major mineral metabolism (Ca, P, and Mg), thus indicating that boron is an essential nutrient for animals. Eight factorially arranged experiments of 6–10 wk durations were done with weanling Sprague-Dawley male rats. One factorially arranged experiment was done with weanling spontaneously hypertensive rats. The variables in each experiment were dietary boron supplements of 0 and 3 μg/g, and dietary magnesium supplements of either 200 (Experiments 1–3) or 100 (Experiments 4–9) and 400 μg/g. In Experiments 7 and 9, a third variable was dietary manganese supplements of 25 and 50 μg/g. Methionine status was varied throughout the series of experiments by supplementing the casein-based diet with methionine and arginine. Findings were obtained indicating that the severity of magnesium deprivation and the methionine status of the rat strongly influence the extent and nature of the interaction between magnesium and boron, and the response to boron deprivation. When magnesium deprivation was severe enough to cause typical signs of deficiency, a significant interaction between boron and magnesium was found. Generally, the interaction was characterized by the deprivation of one of the elements making the deficiency signs of the other more marked. The interaction was most evident when the diet was not supplemented with methionine and especially when the diet contained luxuriant arginine. Signs of boron deprivation were also more marked and consistent when the diet contained marginal methionine and luxuriant arginine. Among the signs of boron deprivation exhibited by rats fed marginal methionine were depressed growth and bone magnesium concentration, and elevated spleen wt/body wt and kidney wt/body wt ratios. Because the boron supplement of 3 μg/g did not make the dietary intake of this element unusual, it seems likely that the response of the rats to dietary boron in the present study were manifestations of physiological, not pharmacological, actions, and support the hypothesis that boron is an essential nutrient for the rat. Mentions of a trademark or proprietary product does not consitute a guarantee or warranty of the product by the US Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.     

High Dietary Intake of Sodium Selenite Does Not Affect Gene Mutation Frequency in Rat Colon and Liver

Our previous studies have shown that selenium (Se) is protective against dimethylhydrazine (DMH)-induced preneoplastic colon cancer lesions, and protection against DNA damage has been hypothesized to be one mechanism for the anticancer effect of Se. The present study was designed to determine whether dietary selenite affects somatic mutation frequency in vivo. We used the Big Blue transgenic model to evaluate the in vivo mutation frequency of the cII gene in rats fed either a Se-deficient (0 μg Se/g diet) or Se-supplemented diet (0.2 or 2 μg Se/g diet; n = 3 rats/diet in experiment 1 and n = 5 rats/group in experiment 2) and injected with DMH (25 mg/kg body weight, i.p.). There were no significant differences in body weight between the Se-deficient and Se-supplemented (0.2 or 2 μg Se/g diet) rats, but the activities of liver glutathione peroxidase and thioredoxin reductase and concentration of liver Se were significantly lower (p < 0.0001) in Se-deficient rats compared to rats supplemented with Se. We found no effect of dietary Se on liver 8-hydroxy-2′-deoxyguanosine. Gene mutation frequency was significantly lower in liver (p < 0.001) than that of colon regardless of dietary Se. However, there were no differences in gene mutation frequency in DNA from colon mucosa or liver from rats fed the Se-deficient diet compared to those fed the Se-supplemented (0.2 or 2 μg Se/g diet) diet. Although gene mutations have been implicated in the etiology of cancer, our data suggest that decreasing gene mutation is not likely a key mechanism through which dietary selenite exerts its anticancer action against DMH-induced preneoplastic colon cancer lesions in a Big Blue transgenic rat model. The US Department of Agriculture, Agricultural Research Service, Northern Plains Area, is an equal opportunity/affirmative action employer and all agency services are available without discrimination. Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the US Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable. This work was supported by the US Department of Agriculture and National Cancer Institute.     

Principles of nonlinear regression modeling

Summary Five principles govern the selection of nonlinear regression models for bacterial growth. Examples are given of the various ways in which researchers have approached the problems of nonlinear regression modeling together with some discussion of linear modeling.Reference to a brand or firm name does not constitute endorsement by the US Department of Agriculture over others of a similar nature not mentioned.     

MKES Tools: A microbial kinetics expert system for developing and assessing food production systems

Summary MKES Tools is a microbial kinetics expert system for developing food production systems and assessing product safety. The specific information required as input are: (1) a flowchart of the production system, (2) the factors affecting the survival and growth of food-borne pathogens and (3) the ranges of variation for each factor's parameters. With this information, MKES Tools simulates the growth and survival of pathogenic microorganisms when subjected to many different factor/parameter situations. The responses obtained are then used to estimate the significance of each factor's parameters.Reference to a brand or firm name does not constute endorsement by the US Department of Agriculture over others of a similar nature not mentioned.     

Qualitative and quantitative methodologies for determination of airborne microorganisms at concentrated animal-feeding operations

The generation of airborne microorganisms from concentrated animal-feeding operations (CAFOs) is a concern from a human and animal health perspective. To better understand the airborne microorganisms found in these environments, a number of collection and analytical techniques have been utilized and will be discussed in this review. The most commonly used bioaerosol collection method is the liquid impingement format, which is suitable with a number of culture-based and non-culture molecular-based approaches, such as polymerase chain reaction. However, the vast majority of airborne microorganism studies conducted at CAFOs utilize culture-based analyses. Because of the limitations often associated with culture-based analyses, we focused our discussion on the application of molecular-based techniques to identify and/or quantify microorganisms, as they have promising application in bioaerosol research. The ability to rapidly characterize airborne microorganisms will help to ensure protection of public and environmental health. The use or mention of any commercial products does not imply any endorsement of that product by either the authors or the US Department of Agriculture.     

Development of an automated plant culture system

An apparatus was constructed that could be used to grow plant tissues, organs, and whole plantlets under sterile conditions. This system accommodated independent or multiple concurrent growth of cultures. Growth of plants either equalled or exceeded that observed using the manual transfer procedure. The automated plant culture system (APCS) consists of silicone tubing, 2 impeller pumps, 2 glass medium reservoir bottles, a 3-way stainless steel valve, a plant culture chamber, and an interface module containing relay boards. Control of the APCS is through interfacing with a microcomputer (e.g. Apple IIe or Atari 400). The computer controlled medium introduction, evacuation, and replenishment in a sterile environment. The APCS was inexpensively constructed and provides a labor-saving, long-term method to culture plants in vitro.Mention of a trade name or proprietary product in the paper does not constitute a guarantee or warranty of the product by the US Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.     

Two bacteria causing farmer's lung: Fine structure ofThermoactinomyces vulgaris andSaccharopolyspora rectivirgula

Larval cuticle ofHelicoverpa (Heliothis)zea and yeast extract added to a minimal medium (MM) induced germination of conidia ofNomuraea rileyi whereas sterile distilled water or MM alone did not. Yeast extract increased mycelial yield, but when cuticle was added, mycelial yield significantly decreased. Proteases and chitinases ofN. rileyi were only expressed when cuticle was added to the MM.This article reports the results of research only. Mention of a proprietary product in this paper does not constitute a recommendation for use by US Department of Agriculture.     

Ultrasonic neuromodulation by brain stimulation with transcranial ultrasound

Brain stimulation methods are indispensable to the study of brain function. They have also proven effective for treating some neurological disorders. Historically used for medical imaging, ultrasound (US) has recently been shown to be capable of noninvasively stimulating brain activity. Here we provide a general protocol for the stimulation of intact mouse brain circuits using transcranial US, and, using a traditional mouse model of epilepsy, we describe how to use transcranial US to disrupt electrographic seizure activity. The advantages of US for brain stimulation are that it does not necessitate surgery or genetic alteration, but it confers spatial resolutions superior to other noninvasive methods such as transcranial magnetic stimulation. With a basic working knowledge of electrophysiology, and after an initial setup, ultrasonic neuromodulation (UNMOD) can be implemented in less than 1 h. Using the general protocol that we describe, UNMOD can be readily adapted to support a broad range of studies on brain circuit function and dysfunction.     

Development of detached wheat spikelets in culture

A liquid culture medium in cluster culture dishes supported development of detached wheat spikelets from 7 days pre-anthesis to grain maturity. Development of florets in vitro closely resembled that in vivo as revealed by the growth of anthers, ovaries, and the viability of developing embryos. The number and viability of pollen produced and percentage seed set, however, were significantly lower in cultured spikelets. The developing grain was grown to maturity in vitro by transfering the spikelets into fresh liquid medium every two weeks. The culture of wheat spikelets represents a new experimental tool for studying developmental phenomena and host-pathogen interactions in wheat.The research was supported by the Agricultural Research Service, US Department of Agriculture, in cooperation with the Agricultural Experiment Station, Oregon State University; Technical Paper No 8638 of the latter. Mention of a commercial product does not represent an endorsement of the product by the USDA or imply approval to the exclusion of other comparable products.     

Time to turbidity measurement as a tool for modeling spoilage byLactobacillus

Summary A method has been proposed to obtain growth rate estimates from simple time-to-visible-growth measurements by means of inoculum variation. In case the data are censored an algorithm using a maximum likelihood estimation method is given. Growth rates forLactobacillus plantarum obtained by this method have been used to develop a model for the prediction of the growth rate as a function of temperature and pH. The model was validated by plate counts. It can be applied in a pH range of 3.2 to 8 and a temperature range of 6 to 21 °C.Mention of brand or firm names does not constitute an endorsement by the US Department of Agriculture over others of a similar nature not mentioned.     

Symptomatology and histopathology of fibrous roots of rough lemon (citrus limon) infected with Fusarium solani

Fibrous-root decay and epidermal and cortical sloughing were common on blight trees in two citrus groves with severe symptoms in October 1975. These symptoms were present to varying extent on blight trees in other groves, and some fibrous-root decline also was present on apparently healthy trees. Fusarium solani was present in declining fibrous roots of diseased and healthy trees and occurrence appeared to be limited to the fibrous roots. Fusarium infection resulted in early cortical degeneration, leaving epidermal sleeves on intact, infected steles. Generally, in the xylem and cortex with advanced symptoms, only chlamydospores were present. Sites of early infection conained abundant hyphae and immature chlamydospores. Hyphae penetrated the cortex intracellularly and intercellularly, and all cell types of the xylem appeared to be infected predominantly through pits. Fusarium was found on the surface of the epidermis and in broken epidermal cells of healthy-appearing and diseased roots.This paper reports the results of research only. Mention of a pesticide in this paper does not constitute a recommendation for use by the U.S. Department of Agriculture, nor does it imply registration under FIFRA as amended. Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.     

Callus formation from protoplasts of a maize cell culture

Summary A finely dispersed cell suspension culture from the friable callus of the Black Mexican Sweet line of maize was obtained. Protoplasts from this cell culture, when grown in a simplified medium described here, showed sustained cell divisions and gave rise to callus.Abbreviations 2,4-D 2,4-dichlorophenoxyaceticacid - SDS sodium dodecyl sulfate Cooperative Investigation, United States Department of Agriculture and Institute of Food and Agricultural Sciences, University of Florida, Florida Agricultural Experiment Station Journal Series No. 2453. Mention of a trademark, proprietary, product, or vendor does not constitute a guarantee or warrantly of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products or vendors that may also be suitable     

Linear-Arrhenius models for bacterial growth and death and vitamin denaturations

Summary The development of the quantitative, linear-Arrhenius model of Davey for predicting bacterial growth and death (inactivation) is reviewed. The applicability of the model to published data from independent researchers for both the growth phase and lag phase, involving combined environmental factors (T, a _w) is illustrated. Also illustrated is its applicability to thermal inactivation kinetics and vitamin denaturation (with combinedT, pH). Integration of the model to produce complex models describing the thermal sterilization of liquid is demonstrated. Advantages of the model, including its simplicity and the fact that the coefficients to build the model can be obtained easily by relatively unsophisticated users, are highlighted in a comparison with other models.Mention of brand or firm names does not constitute an endorsement by the US Department of Agriculture over others of a similar nature not mentioned.     

A new chromogenic medium for the isolation of Listeria spp

A new medium is described for the isolation of Listeria spp. from foods and environmental samples. It is based on a modified Oxford medium in which 3,4-cyclohexenoesculetin-beta-D-glucoside replaces aesculin. Positive colonies are intensely black with the advantage that the pigment does not diffuse into the medium. The medium, when tested alongside the US Department of Agriculture (spiked samples) and Food and Drug Administration (naturally contaminated samples) isolation procedures, performed significantly better than the current formulations (34% more confirmed positives from naturally contaminated samples) with a reduction of 1 d in the assay time for most samples.     

Direct screening for acid phosphatase production on bcip-agar plates

Summary A direct screening procedure for detection of acid phosphatase activity was established using medium containing 5-bromo-4-chloro-3-indolyl phosphate. Production of acid phosphatase could be suppressed by adding phosphate. This acid phosphatase activity as well as studying its regulation.Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by the U. S. Department of Agriculture and does not imply its approval to the exclusion of other products or vendors that may also be suitable.     

Retardation of tree growth by injection of plant growth regulators

Previously topped American sycamore (Platanus occidentalis L.), cottonwood (Populus deltoides Bartr. ex Marsh), water oak (Quercus nigra L.), and bigleaf maple (Acer macrophyllum Pursh) trees were injected with aqueous solutions of maleic hydrazide or dikegulac-sodium in April-June, 1979 at various locations around the United States. Measurements made later in the autumn showed that dikegulac-sodium reduced sprout regrowth in all four species, whereas maleic hydrazide was only effective in controlling regrowth of American sycamore and cottonwood. The effects of dikegulac persisted through the second growing season. Significant variability was observed among treated trees and must be reduced in order to achieve consistent growth responses from an application of growth retardants.This paper reports the results of research only. Mention of a growth regulator does not consitute a recommendation for use by the U.S. Department of Agriculture nor does it imply registration under FIFRA as amended. Mention of a trademark or propriety product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.     

Dietary folate affects the response of rats to nickel deprivation

Because vitamin B₁₂ and Ni are known to interact and because of the similar metabolic roles of vitamin B₁₂ and folate, an experiment was performed to determine the effect of dietary folate on Ni deprivation in rats. A 2×2 factorially arranged experiment used groups of nine weanling Sprague-Dawley rats. Dietary variables were Ni, as NiCl₂·6H₂O, 0 or 1 μg/g; and folic acid, 0 or 2 mg/kg. The basal diet, based on skim milk, contained less than 20 ng Ni/g. After 54 d, an interaction between dietary Ni and folate affected several variables including erythrocyte folate, plasma amino acids, and femur trace elements. For example, folate deprivation decreased erythrocyte folate; folate supplementation to the Ni-supplemented rats caused a larger increase in erythrocyte folate concentration than did folate supplementation to the Ni-deprived rats. Also, dietary Ni affected several plasma amino acids important in one-carbon metabolism (e.g., Ni deprivation increased the plasma concentrations of glycine and serine). This study shows that dietary Ni, folate, and their interaction can affect variables associated with one-carbon metabolism. This study does not show a specific site of action of Ni but it indicates that Ni may be important in processes related to the vitamin B₁₂-dependent pathway in methionine metabolism, possibly one-carbon metabolism. US Department of Agriculture, Agricultural Research Service, Northern Plans Area is an equal opportunity/affirmative action employer and all agency services are available without discrimination.     

The physical location of fourteen RFLP markers in rice (Oryza sativa L.)

A biotin-labeled in situ hybridization technique was used in order to physically map RFLP markers to the chromosomes of rice (Oryza sativa L.). Fourteen RFLP markers, associated with the ends of the linkage groups on rice chromosomes 7, 8, 11, 12, were physically mapped onto specific regions of the chromosomes. The average detection rate of in situ hybridization was 5.91%. The markers were located on seven different chromosome arms. Ten of the fourteen markers were distributed near the chromosome ends. This demonstrated that the RFLP linkage groups involved covered a wide physical distance and that the centromeric region was bisected by all but one linkage group. Two markers covered a short genetic distance but were physically distant, while two covering a longer genetic distance were physically closer together. This indicates that considerable variation can, and does, exist between genetic and physical maps.This paper is a contribution of the U.S. Department of Agriculture, Agricultural Research Service, and Missouri Agricultural Experiment Station, Journal Series No. 11 882All programs and services of the U.S. Department of Agriculture are offered on a nondiscriminatory basis without regard to race, color, national origin, religion, sex, age, marital status, or handicapThis paper reports the results of research only. Mention of a proprietary product does not constitute an endorsement or a recommendation for its use by the U.S. Department of Agriculture or the University of Missouri     

The development of monoclonal antibodies against the cytokinin zeatin riboside

Seven monoclonal anti-zeatin riboside antibodies were characterized by radioimmunoassay (RIA) and found to measure femtomole (10^–15 M) quantities (20 pg) of this cytokinin. The antibodies had different measuring ranges defined by the linear portion of the logit/log plots; slopes and intercepts of the line varied considerably between the antibodies. Competitive binding trials againstcis-zeatin riboside (cZR), dihydrozeatin riboside (diHZR), zeatin (Z), and isopentenyl adenosine (iPA) showed differences among the seven antibodies in their cross-reactivities towards these structurally related cytokinins. It was possible to combine selected antibodies to provide a mixture with a predictable measuring range and cross-reactivity; the ability to prepare a highly specific reagent in this manner with well-defined reactivity was noted and differences between monoclonal antibody and polyclonal antiserum probes for measurement of cytokinins were discussed.The research was supported by the Agricultural Research Service, U.S. Department of Agriculture, Technical Paper No. 7373 of the Oregon Agricultural Experiment Station. Mention of a trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by the U.S. Department of Agriculture and does not imply approval to the exclusion of other products that may also be available.