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1992

Iowa State University

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Articles 1 - 16 of 16

Full-Text Articles in Life Sciences

Nest Usurpation, Supersedure And Colony Failure Contribute To Africanization Of Commercially Managed European Honey Bees In Venezuela, Robert G. Danka, Richard L. Hellmich, Thomas E. Rinderer Dec 1992

Nest Usurpation, Supersedure And Colony Failure Contribute To Africanization Of Commercially Managed European Honey Bees In Venezuela, Robert G. Danka, Richard L. Hellmich, Thomas E. Rinderer

Richard L Hellmich

The fates of 58 colonies in 4 apiaries managed commercially for honey production in northwest Venezuela were determined during 15 months. All colonies had been previously requeened with marked European queens. Heritage of new queens (European daughter replacements versus Africanized usurpers) was traced by mitochondrial DNA and morphological characteristics of worker progeny. Three usurpations (5% of colony fates, at a rate of 4.7% of colonies per year) occurred. These colonies showed congruent African-derived mitochondrial DNA and Africanized morphology. Supersedures accounted for much of the introgression of African genes into the test apiaries. Twenty-eight colonies (48%) superseded their queens once, three …


Isolation And Characterization Of The Tricarboxylate Transporter From Pea Mitochondria, Cecilia A. Mcintosh, David J. Oliver Dec 1992

Isolation And Characterization Of The Tricarboxylate Transporter From Pea Mitochondria, Cecilia A. Mcintosh, David J. Oliver

David J. Oliver

The tricarboxylate transporter was solubilized from pea (Pisum sativum) mitochondria with Triton X-114, partially purified over a hydroxylapatite column, and reconstituted in phospholipid vesicles. The proteoliposomes exchanged external [14C]citrate for internal citrate or malate but not for preloaded D,L-isocitrate. Similarly, although external malate, succinate, and citrate competed with [14C]citrate in the exchange reaction, D,L-isocitrate and phosphoenolpyruvate did not. This tricarboxylate transporter differed from the equivalent activity from animal tissues in that it did not transport isocitrate and phosphoenolpyruvate. In addition, tricarboxylate transport in isolated plant mitochondria, as well as that measured with the partially purified and reconstituted transporter, was less …


Predicting The Growth Of Salmonella Typhimurium On Beef By Using The Temperature Function Integration Technique, James S. Dickson, G. R. Siragusa, J. E. Wray Jr. Nov 1992

Predicting The Growth Of Salmonella Typhimurium On Beef By Using The Temperature Function Integration Technique, James S. Dickson, G. R. Siragusa, J. E. Wray Jr.

James S. Dickson

Lag and generation times for the growth of Salmonella typhimurium on sterile lean beef were modeled as functions of cooling time under various carcass-chilling scenarios. Gompertz growth models were fit to the log10 colony counts over time at each of six temperatures in the range of 15 to 40 degrees C. Lag and generation times were defined as the points at which the second and first derivatives, respectively, of each growth curve attained a maximum. Generation time and lag time parameters were modeled as functions of temperature by use of exponential-decay models. The models were applied to typical beef carcass-cooling …


Identification And Prevalence Of A Genetic Defect That Causes Leukocyte Adhesion Deficiency In Holstein Cattle, Dale E. Shuster, Marcus E. Kehrli Jr., Mark R. Ackermann, R. O. Gilbert Oct 1992

Identification And Prevalence Of A Genetic Defect That Causes Leukocyte Adhesion Deficiency In Holstein Cattle, Dale E. Shuster, Marcus E. Kehrli Jr., Mark R. Ackermann, R. O. Gilbert

Mark R. Ackermann

Two point mutations were identified within the gene encoding bovine CD18 in a Holstein calf afflicted with leukocyte adhesion deficiency (LAD). One mutation causes an aspartic acid to glycine substitution at amino acid 128 (D128G) in the highly conserved extracellular region of this adhesion glycoprotein, a region where several mutations have been found to cause human LAD. The other mutation is silent. Twenty calves with clinical symptoms of LAD were tested, and all were homozygous for the D128G allele. In addition, two calves homozygous for the D128G allele were identified during widespread DNA testing, and both were subsequently found to …


Nad+-Linked Isocitrate Dehydrogenase: Isolation, Purification, And Characterization Of The Protein From Pea Mitochondria, Cecilia A. Mcintosh, David J. Oliver Sep 1992

Nad+-Linked Isocitrate Dehydrogenase: Isolation, Purification, And Characterization Of The Protein From Pea Mitochondria, Cecilia A. Mcintosh, David J. Oliver

David J. Oliver

The NAD+-dependent isocitrate dehydrogenase from etiolated pea (Pisum sativum L.) mitochondria was purified more than 200-fold by dye-ligand binding on Matrix Gel Blue A and gel filtration on Superose 6. The enzyme was stabilized during purification by the inclusion of 20% glycerol. In crude matrix extracts, the enzyme activity eluted from Superose 6 with apparent molecular masses of 1400 ± 200, 690 ± 90, and 300 ± 50 kD. During subsequent purification steps the larger molecular mass species disappeared and an additional peak at 94 ± 16 kD was evident. The monomer for the enzyme was tentatively identified at 47 …


Diversity Among Rhizobia Effective With Robinia Pseudoacacia L, Janet Mccray-Batzli, William R. Graves, Peter Van Berkum Jul 1992

Diversity Among Rhizobia Effective With Robinia Pseudoacacia L, Janet Mccray-Batzli, William R. Graves, Peter Van Berkum

William R Graves

The diversity of rhizobia that form symbioses with roots of black locust (Robinia pseudoacacia L.), an economically important leguminous tree species, was examined by inoculating seedling root zones with samples of soil collected from the United States, Canada, and China. Bacteria were isolated from nodules, subcultured, and verified to be rhizobia. The 186 isolates varied significantly in their resistance to antibiotics and NaCl, their growth on different carbohydrates, and their effect on the pH of culture media. Most isolates showed intermediate antibiotic resistance, the capacity to use numerous carbohydrates, and a neutral to acid pH response. Isolates had greater similarity …


H-Protein Of The Glycine Decarboxylase Multienzyme Complex: Complementary Dna Encoding The Protein From Arabidopsis Thaliana, David J. Oliver Apr 1992

H-Protein Of The Glycine Decarboxylase Multienzyme Complex: Complementary Dna Encoding The Protein From Arabidopsis Thaliana, David J. Oliver

David J. Oliver

The glycine decarboxylase multienzyme complex is composed of four component enzymes, the 100-kD P-protein (a pyridoxal 5-phosphate-dependent amino acid decarboxylase), the 14-kD H-protein (a lipoamide-containing carrier protein), the 45-kD T-protein (a tetrahydrofolate transferase), and the 59-kD L-protein (lipoamide dehydrogenase) (5). The Iipoamide cofactor of the H-protein carries reaction intermediates between the active sites of the other three component proteins. These proteins form a large molecular weight complex (4) within the matrix ofleaf mitochondria where, together with the enzyme serine hydroxymethyltransferase, it catalyzes the photorespiratory conversion of two molecules of glycine to one each of serine, NH3, and CO2 with the …


Soy Protein, Phytate, And Iron Absorption In Humans, Richard F. Hurrell, Marcel-A Juillerat, Manju B. Reddy, Sean R. Lynch, Sandra A. Dassenko, James D. Cook Mar 1992

Soy Protein, Phytate, And Iron Absorption In Humans, Richard F. Hurrell, Marcel-A Juillerat, Manju B. Reddy, Sean R. Lynch, Sandra A. Dassenko, James D. Cook

Manju B. Reddy

The effect of reducing the phytate in soy-protein isolates on nonheme-iron absorption was examined in 32 human subjects. Iron absorption was measured by using an extrinsic radioiron label in liquid-formula meals containing hydrolyzed corn starch, corn oil, and either egg white or one of a series ofsoy-protein isolates with different phytate contents. Iron absorption increased four- to fivefold when phytic acid was reduced from its native amount of 49-8.4 to < 0.01 mg/g of isolate. Even relatively small quantities of residual phytate were strongly inhibitory and phytic acid had to be reduced to < 0.3 mg/g of isolate (corresponding to < 10 mg phytic acid/meal) before a meaningful increase in iron absorption was observed. However, even after removal ofvirtually all the phytic acid, iron absorption from the soy-protein meal was still only half that of the egg white control. It is concluded that phytic acid is a major inhibitory factor of iron absorption in soy-protein isolates but that other factors contribute to the poor bioavailability of iron from these products.


Microbiological Decontamination Of Food Animal Carcasses By Washing And Sanitizing Systems: A Review, James S. Dickson, Maynard E. Anderson Feb 1992

Microbiological Decontamination Of Food Animal Carcasses By Washing And Sanitizing Systems: A Review, James S. Dickson, Maynard E. Anderson

James S. Dickson

Microbial contamination of animal carcasses is a result of the necessary procedures required to process live animals into retail meat. The contamination can be minimized by good manufacturing processes, but the total elimination of foodborne pathogenic microorganisms is difficult, if not impossible. A variety of methods have been developed to reduce the levels of contaminating bacteria on carcasses, although most of the current methods focus on washing and sanitizing procedures. The commonly used sanitizing agents include hot water, chlorine, and short-chain organic acids. The effectiveness of these compounds varies by the concentration used, the temperature of the sanitizers and contact …


Micro And Macromorphology Of Recycled Fiber And Wood, Douglas D. Stokke Jan 1992

Micro And Macromorphology Of Recycled Fiber And Wood, Douglas D. Stokke

Douglas D. Stokke

Wood is a major industrial raw material, with U.S. consumption approaching that of aluminum, plastics, cement, and steel combined. Partially as a result of the magnitude of wood and wood products in use, these products constitute a substantial portion of the solid waste stream. In order to reduce the amount of wood and wood fiber disposed in landfills, efforts to recycle these materials into useful products such as structural composites are needed. The success of such conversion depends in part on knowledge of the morphological characteristics of various sources of secondary wood and wood fibers, and the influence of wood …


Intestinal Adenocarcinoma Of The Ileocecal Junction In A Chicken, James R. Andreasen Jr., Claire B. Andreasen Jan 1992

Intestinal Adenocarcinoma Of The Ileocecal Junction In A Chicken, James R. Andreasen Jr., Claire B. Andreasen

Claire B. Andreasen

An 89-week-old male chicken was presented with signs of depression, emaciation, and weakness. At necropsy, a stricture was found at the ileocecal junction that resulted in blockage and dilation of the ileum proximal to the stricture. Histologically, neoplastic epithelial cells that contained mucin had invaded the intestinal wall and produced a fibrous connective tissue reaction. The lesion was diagnosed as scirrhous intestinal adenocarcinoma.


Forage Quality Of Alfalfa Protected By Resistance To Bacterial Leaf Spot, Andrew W. Lenssen, E. L. Sorensen, G. L. Posler, D. L. Stuteville Jan 1992

Forage Quality Of Alfalfa Protected By Resistance To Bacterial Leaf Spot, Andrew W. Lenssen, E. L. Sorensen, G. L. Posler, D. L. Stuteville

Andrew W. Lenssen

Bacterial leaf spot (BLS), caused by Xanthomonas campestris pv. arfalfae Dye (Xca ), can prevent stand establishment and decrease the yield and persistence of alfalfa (Medicago sativa L.) in the central USA. Previous studies have shown that BLS inoculation may affect concentrations of monophenolic compounds and thus alter the forage quality of alfalfa. In a controlled environment, comparisons were made of forage quality, including phenolic monomers, of alfalfa cv. Kanza (susceptible) and KS76 germplasm (derived from Kanza, resistant) with and without inoculation with Xca. The cultivarx inoculation interactions were non-significant (P> 0.05 ) for all parameters determined for leaves and …


Inhibition Of Listeria Monocytogenes On Beef Tissue By Application Of Organic Acids Immobilized In A Calcium Alginate Gel, James S. Dickson, Gregory R. Siragusa Jan 1992

Inhibition Of Listeria Monocytogenes On Beef Tissue By Application Of Organic Acids Immobilized In A Calcium Alginate Gel, James S. Dickson, Gregory R. Siragusa

James S. Dickson

Organic acids added to calcium alginate gels and immobilized on lean beef tissue inoculated with LLtetia monocytogenes (Lm) reduced the population significantly more than did acid treatment alone. Lactic acid (1.7% v/v) immobilized in alginate reduced counts by 1.3 log,, units vs 0.03 log unit decrease from the acid treatment alone. Acetic acid (2% v/v) reduced counts 1.5 and 0.25 log units, respectively. Over 7 days, Lm proliferated in samples without acid and/or alginate treatment. Differential counts on selective and non-selective agars indicated sublethal cellular injury occurred. Alginate coatings did not enhance acid inhibition on fat tissue. Immobilized agents may …


Acetic Acid Action On Beef Tissue Surfaces Contaminated With Salmonella Typhimurium, James S. Dickson Jan 1992

Acetic Acid Action On Beef Tissue Surfaces Contaminated With Salmonella Typhimurium, James S. Dickson

James S. Dickson

Beef tissue surfaces (lean and fat) were artificially contaminated with Salmonella typhimurium and then sanitized with 2% acetic acid. The reduction in bacterial population by the acid treatment was consistently proportional to the initial inoculum level for both tissue types. Increasing the amount of organic material in the inoculating menstra reduced the bactericidal effects of acetic acid on Salmonella typhimurium on fat tissue, although there was no change in effectiveness on lean tissue. Acid treatment sublethally injured about 65% of the population on both lean and fat tissue, and the residual effects of the acid resulted in a 1 log …


Feeding Patterns Of Growing Pigs At Warm Constant And Cyclic Temperatures, Hongwei Xin, James A. Deshazer Jan 1992

Feeding Patterns Of Growing Pigs At Warm Constant And Cyclic Temperatures, Hongwei Xin, James A. Deshazer

Hongwei Xin

Feeding behavior of ad libitum-fed^ 39-kg, crossbred gilts was investigated under mean ambient temperatures of 30.8° C with 0, 7, and 16.6° C cycles. Average meal size, 160 to 170 g/pig; meal duration, 13.3 to 14.3 min; and ingestion rate, 12.2 g/min-pig did not appear to be influenced by the temperature conditions. However, meal frequency, 9 to 11 per day, tended to be reduced by elevated hours of exposure to high temperatures. Consequently daily feed intake of the pigs was signiflcantly less in the 16.6° C cycle treatment than in the 0 or 7° C cycle treatments (P<0.01). Feed consumed during the lighting period (0600 h to 2100 h) accounted for 75%, 61%, and 37% of daily feed intake for the 0, 7, and 16.6° C cycle treatments, respectively. Pigs under the 0° C cycle had most feeding activities in the afternoon and evening (55% of daily feed intake). In contrast, pigs under the 16.6° C cycle had most feeding events at night and early morning (91 % of daily feed intake).


Responses Of Pre-Fasted Growing Turkeys To Acute Heat Exposure, Hongwei Xin, James A. Deshazer, Mary M. Beck Jan 1992

Responses Of Pre-Fasted Growing Turkeys To Acute Heat Exposure, Hongwei Xin, James A. Deshazer, Mary M. Beck

Hongwei Xin

Nicholas turkeys at the age of 15 to 16 weeks were fasted for 24 hours in a moderate environment and then subjected to acute heat exposures of various dry-bulb and wet-bulb temperatures (T^u, and T^jj). Total feed intake was not influenced by T^^ of 32*' C, 36"* C or 40° C (P > 0.10), although differences existed in dynamic feeding profiles. Total heat production rate (THP) varied quadratically with T^^, and respiratory quotient (RQ) decreased linearly with T^u,. The lower RQ values at the higher T^i^ levels may have resulted from reduced feed assimilation. No differences were detected on feed intake, …