Screening methods and identification of QTLs associated with late maturity α-amylase in wheat

The synthesis of high levels of germination-type (high pI isozymes) α-amylase was induced in wheat genotypes prone to late maturityα-amylase (LMA) following the exposure of detached tillers to cool temperature during grain development. The detached tiller method was successfully applied to a range of genotypes and to a doubled haploid (DH) population derived from the cross Cranbrook (LMA genotype) × Halberd (low amylase). The number of grains in ripe, treated tillers that contained high pI α-amylase isozymes was measured using an ELISA antibody kit highly specific for high pI isozymes. Quantitative trait loci (QTL) controlling the expression of LMA in wheat were detected in DH population Cranbrook × Halberd. The DH population and parents were sown in 2 replicated sowings at the same location with sowing times differing by 2 weeks. QTL analyses were conducted separately for each sowing, but results from both sowings were consistent and indicated a highly significant (it p > 0.01) QTL on the long arm of chromosome7B, with Cranbrook contributing the higher value allele. A second QTL with less significant effect was found on the long arm of chromosome 3B, on the basis of data from the first sowing. This revised version was published online in August 2006 with corrections to the Cover Date.     

Expression of late maturity α-amylase in wheat containing gibberellic acid insensitivity genes

Summary Two wheat cultivars, Spica and Lerma 52, which consistently produce high levels of -amylase during the later stages of grain development (late maturity -amylase), were crossed with a set of four near-isogenic lines carrying the tall (rht) allele or one of the dwarfing genes Rht1, Rht2 or Rht3 (GA-insensitive alleles). The F₁ and F₂ populations were developed and analysed for grain -amylase and plant height. The Rht3 gene exhibited the strongest influence on plant height and strongly inhibited new -amylase synthesis during the later part of grain ripening. By comparison, Rht1 and Rht2 had a less pronounced effect but still significantly reduced the expression of late maturity -amylase. These observations suggest that gibberellic acid is involved either directly or indirectly in this phenomenon. The implications of the effect of dwarfing genes on expression of late maturity -amylase are discussed in relation to cultivar improvement and to the identification and control of high -amylase germplasm.     

Interactions of Genotype and Glutenin Subunit Composition on Breadmaking Quality of Durum 1AS•1AL‐1DL Translocation Lines

Dual‐purpose durum (Triticum turgidum L. subsp. durum) wheat, having both good pasta and breadmaking quality, would be an advantage in the market. In this study, we evaluated the effects of genotype and varying HMW and LMW glutenin subunit composition on durum breadmaking quality. Genotypes included five near‐isogenic backgrounds that also differed by variability at the Glu‐D1d (HMW subunits 1Dx5+1Dy10), Glu‐B1 (presence or absence of subunit 1By8), and Glu‐B3 (LMWI or LMWII pattern) loci. Quality tests were conducted on genotypes grown at five North Dakota locations. Genotype had a stronger influence on free asparagine content than glutenin subunit composition. Genotypes carrying Glu‐D1d had higher glutenin content than lines that did not carry Glu‐D1d. Among Rugby translocation genotypes, lines carrying LMWI had higher gliadin content and better loaf volume than genotypes carrying LMWII. Absence of 1By8 produced major reductions in loaf volume in nontranslocation lines regardless of whether LMWI or LMWII was present. In contrast, the presence of Glu‐D1d compensated well for the absence of 1By8 regardless of which LMW pattern was present. The durum genotypes did not have loaf volumes equal to bread wheat cultivars, and results suggest that improved extensibility is needed to improve durum breadmaking quality.     

Evaluation of a circumferential femoral head osteophyte as an early indicator of osteoarthritis characteristic of canine hip dysplasia in dogs

OBJECTIVE: To determine the relationship between a circumferential femoral head osteophyte (CFHO) and osteoarthritis characteristic of canine hip dysplasia, and to ascertain whether CFHO, like osteoarthritis, varies between diet-restricted and control-fed dogs. DESIGN: Longitudinal cohort study. ANIMALS: 48 Labrador Retrievers. PROCEDURES: Dogs were paired by size, sex, and litter and assigned to 1 of 2 equal groups at 2 months of age. The control-fed group was fed ad libitum, and the diet-restricted group was fed 25% less on a pairwise basis of the same diet for life. The dogs' hip joints were radiographed yearly for life. Each radiograph was evaluated for radiographic signs of osteoarthritis characteristic of hip dysplasia and for the presence and severity of a CFHO. RESULTS: 41 of the 48 (85.4%) dogs had a CFHO, which was detected at a median age of 5.4 years, and 33 of those 41 (80.5%) developed radiographic evidence of osteoarthritis. Nineteen (79.2%) dogs in the diet-restricted group and 22 (91.7%) in the control-fed group had a CFHO at a median age of 9 and 3 years, respectively. Of the dogs with a CFHO, 12 (63.2%) in the diet-restricted group and 20 (90.0%) in the control-fed group developed radiographic evidence of osteoarthritis characteristic of hip dysplasia at a median age of 11 and 6.5 years, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated a relationship between the CFHO and subsequent development of radiographic signs of osteoarthritis. If a CFHO is present in Labrador Retrievers, it might be considered an early indicator of osteoarthritis.     

Teaching veterinary students beef production medicine with student/producer teams

Veterinary colleges face difficulties in meeting the demand for rural veterinarians with the scope to practice quality production medicine. Increasing population density around veterinary colleges, retaining the interest of students with a background in animal agriculture, and educating students without a farm background requires that veterinary colleges consider innovative ways to not only teach traditional food-animal practice but give future veterinarians the advanced skills the food industry demands. This article describes a three-year elective program, Beef Records Analysis, in which beef production medicine is taught by teaming a student and a beef producer together early in the student's veterinary education. These producer/student teams complete risk assessments, balance rations, collect financial and production information, and evaluate back-grounding and feedlot enterprises. Students learn how to evaluate their producers using industry benchmarks and past performance records and how to communicate their findings back to their producer. Producers often make management decisions based on the students' findings, and, because the students maintain their relationships with producers for three years, they can assess the outcomes of the producers who follow or ignore their recommendations and interventions. Students share recommendations and outcomes associated with their herd with the entire class. This allows students to learn how to establish best management practices through objective analysis of outcomes of recommended practices of all herds represented in the class. While a formal assessment of the course is needed, the students rate the program very high on evaluations.     

Infections caused by pathogenic free-living amebas (Balamuthia mandrillaris and Acanthamoeba sp.) in horses.

This article describes amebic infections in 4 horses: granulomatous amebic encephalitis caused by Balamuthia mandrillaris and Acanthamoeba culbertsoni and systemic infections caused by Acanthamoeba sp. The former infection occurred in 1 of 4 horses spontaneously without any underlying conditions; the latter amebic infection was perhaps "opportunistic" considering the visceral involvement by this protozoan in association with Aspergillus sp. and/or Escherichia coli and Pseudomonas sp. The clinicopathologic findings and demonstration of the amebic organisms using immunohistochemical techniques, culture, polymerase chain reactions, and electron microscopy are presented.     

Enzyme dynamics during catalysis

Internal protein dynamics are intimately connected to enzymatic catalysis. However, enzyme motions linked to substrate turnover remain largely unknown. We have studied dynamics of an enzyme during catalysis at atomic resolution using nuclear magnetic resonance relaxation methods. During catalytic action of the enzyme cyclophilin A, we detect conformational fluctuations of the active site that occur on a time scale of hundreds of microseconds. The rates of conformational dynamics of the enzyme strongly correlate with the microscopic rates of substrate turnover. The present results, together with available structural data, allow a prediction of the reaction trajectory.     

Late-maturity α-amylase: Low falling number in wheat in the absence of preharvest sprouting

Late maturity α-amylase (LMA), or prematurity α-amylase (PMAA) as it has been termed in the UK, in wheat involves the untimely synthesis of high pI α-amylase during the middle to later stages of grain development and ripening. The enzyme activity is retained in the grain at harvest ripeness, resulting in low falling number and failure to meet receival standards and customer specifications. This phenomenon, which is restricted to specific genotypes, appears to be controlled by 1 or 2 recessive genes acting alone or in combination and in most cases appears to be triggered by a temperature shock. This shock is only effective if it occurs during a window of sensitivity around 25–30 days postanthesis. Expression of LMA is reduced in the presence of dwarfing genes such as Rht1, Rht2 and Rht3 that confer insensitivity to gibberellin. Screening technologies, including molecular markers and high pI-specific ELISA, have been developed to assist wheat breeders and will be required to meet new challenges posed by novel germplasm such as primary synthetic wheats.     

Providing stewardship and leadership for the future of veterinary medical research: a responsibility of the veterinary colleges

As we contemplate responsibilities as well as opportunities in research, it is fair to begin by considering why research is, or should be, important to veterinary schools and colleges, to our profession, and to society. Veterinary research is conducted in many venues, such as colleges of veterinary medicine, veterinary science departments, comparative medicine departments, medical schools, and many other university departments, as well as in industry laboratories, governmental agencies, and other organizations. But schools and colleges of veterinary medicine have a unique and historic responsibility to ensure that our veterinary medical research programs are sufficient in quality, capacity, and depth to meet the research needs of our society. Consequently, my comments will be oriented toward veterinary schools and colleges.     

Effects of microcin 24-producing Escherichia coli on shedding and multiple-antimicrobial resistance of Salmonella enterica serotype typhimurium in pigs

OBJECTIVE: To investigate the effect of an Escherichia that produced microcin 24 (Mcc24) on shedding of of Salmonella enterica serotypeTyphimurium in swine and evaluate evidence of in vivo activation of the Mcc24-mediated, multiple-antibiotic resistance (mar) operon. ANIMALS: 36 crossbred weaned pigs. PROCEDURE: 24 pigs were allocated to 2 groups (12 pigs/group). Pigs in 1 group received daily oral administration of an Mcc24-producing E coli, whereas the other group received a non-Mcc24-producing E coli. All pigs were challenge exposed with Salmonella Typhimurium chi4232. A third group of 6 pigs received Mcc24-producing E coli and was challenge exposed with an Mcc24-sensitive, marA-deleted strain of Salmonella Typhimurium 4232. After challenge exposure, fecal samples from all pigs were cultured to detect shedding of Salmonella Typhimurium and Salmonella Typhimurium isolates were screened for resistance to ciprofloxacin. Fecal samples were collected throughout the study, and tissue samples were collected during necropsy. RESULTS: Differences in shedding of Salmonella Typhimurium were not detected between groups receiving Mcc24-producing or non-Mcc24-producing E coli. No significant differences were found in quantitative analysis between groups receiving Mcc24-producing and non-Mcc24-producing E coli. Evidence of mar activation was not detected. CONCLUSIONS AND CLINICAL RELEVANCE: Microcin-producing E coli did not exert an effect on shedding of SalmonellaTyphimurium or mar activation in pigs. It may be difficult or impractical to create the conditions required for Mcc24 to be an effective part of a food safety intervention to reduce shedding of Salmonella Typhimurium.