Respiratory disease caused by Mycoplasma bovis is enhanced by exposure to bovine herpes virus 1 (BHV-1) but not to bovine viral diarrhea virus (BVDV) type 2

To determine if previous exposure to bovine viral diarrhea virus (BVDV) and bovine herpes virus 1 (BHV-1) type 2 affects the onset of disease caused by Mycoplasma bovis, 6- to 8-month-old beef calves were exposed to BVDV or BHV-1 4 d prior to challenge with a suspension of 3 clinical isolates of M. bovis. Animals were observed for clinical signs of disease and at necropsy, percent abnormal lung tissue and presence of M. bovis were determined. Most animals pre-exposed to BHV-1 type 2 but not BVDV developed M. bovis-related respiratory illness. In a second trial, we determined that a 100-fold reduction in the number of M. bovis bacteria administered to BHV-1 exposed animals reduced the percentage of abnormal lung tissue but not the severity of clinical signs. We conclude that previous exposure to BHV-1 but not BVDV type 2 was a necessary cause of M. bovis-related respiratory diseases in our disease model.     

Responses of farmers to introduction in England and Wales of pre-movement testing for bovine tuberculosis

Pre-movement testing (PrMT) for bovine tuberculosis (bTB) was introduced in England and Wales in 2 phases starting in 2006. This study used questionnaires (n=800, response rate=31%) and analysis of national cattle movement records between January 2003 and February 2007 to investigate the impact of PrMT on specific farm management behaviours. A majority of farmers (65%) believed they had not changed their behaviour in response to PrMT; the main reported changes related to decisions regarding selling of cattle. There was evidence in the cattle movement data that introduction of PrMT resulted in reduction of movements of cattle between farms in those areas which must undertake PrMT. The buying behaviour reported by farmers reflected the tendency to buy locally but some farmers reported that others might be more willing to purchase animals from high-risk areas as a result of increased confidence due to PrMT. However, there was little evidence in the movement data of increased movements from high- to low-risk bTB areas following introduction of PrMT. Analysis of the cattle movement data found increased movement of single animals and decreased movement of large batches (>10) of animals (directly) between farms since the introduction of PrMT.     

Molecular detection of Babesia bovis and Babesia bigemina in white-tailed deer (Odocoileus virginianus) from Tom Green County in central Texas

Serologic and molecular evidence suggest that white-tailed deer in South Texas and North Mexico carry the agents of bovine babesiosis, Babesia bovis and Babesia bigemina. To determine if white-tailed deer in central Texas, which is outside the known occurrence of the vector tick at this time, harbor these parasites, blood samples from free-ranging and captive white-tailed deer (Odocoileus virginianus) in Tom Green County were tested by polymerase chain reaction (PCR) assays for B. bovis and B. bigemina 18S rDNA. Of the 25 samples tested, three (12%) were positive by nested PCR for B. bovis. This identity was confirmed by sequence analysis of the cloned 18S rDNA PCR product. Further confirmation was made by sequence analysis of the rRNA internal transcribed spacer (ITS) 1, 5.8S rRNA gene, and ITS 2 genomic region in two (representing samples from two different ranches) of the B. bovis positive samples. Three samples were positive by B. bigemina nested PCR, but sequencing of the cloned products confirmed only one animal positive for B. bigemina; Theileria spp. DNA was amplified from the other two animal samples. In addition to Theileria spp., two genotypically unique Babesia species sequences were identified among the cloned sequences produced by the B. bigemina primers in one sample. Phylogenetic analysis showed no separation of the deer B. bovis or B. bigemina 18S rDNA, or deer B. bovis ITS region sequences from those of bovine origin. Clarification of the possible role of white-tailed deer as reservoir hosts in maintaining these important pathogens of cattle is critical to understanding whether or not deer contribute to the epidemiology of bovine babesiosis.     

Genetic engineering of maize (Zea mays) for high-level tolerance to treatment with the herbicide dicamba

Herbicide-tolerant crops have been widely and rapidly adopted by farmers in several countries due to enhanced weed control, lower labor and production costs, increased environmental benefits, and gains in profitability. Soon to be introduced transgenic soybean and cotton varieties tolerant to treatments with the herbicide dicamba offer prospects for excellent broadleaf weed control in these broadleaf crops. Because monocots such as maize (Zea mays) can be treated with dicamba only during a limited window of crop development and because crop injury is sometimes observed when conditions are unfavorable, transgenic maize plants have been produced and tested for higher levels of tolerance to treatment with dicamba. Maize plants expressing the gene encoding dicamba monooxygenase (DMO) linked with an upstream chloroplast transit peptide (CTP) display greatly enhanced tolerance to dicamba applied either pre-emergence or postemergence. Comparisons of DMO coupled to CTPs derived from the Rubisco small subunit from either Arabidopsis thaliana or Z. mays showed that both allowed production of transgenic maize plants tolerant to treatment with levels of dicamba (i.e., 27 kg/ha) greatly exceeding the highest recommended rate of 0.56 kg/ha.     

Realized gains from selection for spring wheat grain yield are different in conventional and organically managed systems

Breeding spring wheat (Triticum aestivum L.) specifically for organic production has been suggested by producers and researchers alike. To investigate the effects of management systems on selected spring wheat breeding line performance in multi-location tests in the northern Great Plains, we used a randomly derived population of 79 F6-derived recombinant inbred lines (RILs) from a cross between the Canadian hard red spring wheat cultivar AC Barrie and the CIMMYT derived cultivar Attila. The population, including the parents, was grown on conventionally and organically managed land in 12 environments over 3 years. Direct selection in each management system (10% selection intensity based on grain yield) resulted in three lines being retained in each management system, over the multi-location testing. Gains from 10% selection for grain yield in a ‘selection’ year were 3.4 times greater in conventional multi-site yield trials than in organically managed trials. Two lines (BA 05 and BA 36) ranked in the top 10% of both the conventional and organic selection trial of 2005, remained ranked 2nd and 1st, respectively, under conventional management in multi-site yield trials. However, these lines ranked 53rd and 21st, respectively, for grain yield in the multi-site organic yield trials. Selected lines were each yield stable within the management system in which they were selected. Following replicated multi-location yield trials, three lines from the population (BA 02, 29 and 58) ranked within the highest 10% yielding lines in both conventional and organic systems. The results of this study suggest that selection differences occur across multi-location tests, and that selection for grain yield in organic systems should be conducted within organic systems. It is evident, however, that data obtained from conventional yield trials also has some relevance towards breeding for organic environments.     

Saprophytic fungal-bacterial biomass variations in successional communities of a semi-arid steppe ecosystem

A major goal in attempting to understand plant succession is to assess the implications of fungal and bacterial biomass changes over time as plant-soil systems develop. In this study, the soil fungal and bacterial biomass of three successional semi-arid steppe communities, sampled 4, 12, and 38 years after cultivation ended, were compared with an uncultivated native plant community using microscopic procedures. In the course of the succession, significant increases in fungal hyphal lengths occurred, reaching a maximum in the oldest successional (38-year) community. Active (cytoplasm filled) hyphae decreased along the chronosequence, with the native plant community having the lowest values. Similar decreases in active bacterial biomass values occurred. In contranst, microscopically determined total bacterial numbers did not differ in soils associated with the 4-year-old and native plant communities. The ratio of active bacterial to fungal biomass, which increased over the chronosequence tested in this study, appears to provide a valuable integrative measure of plant-soil resource system development and ecosystem maturity.     

A field evaluation of the Hasl wet-dry deposition collector

Samples of precipitation, dry deposition and total deposition have been obtained from Tutuila Island, American Samoa, since April 1976. These collections are part of a study of global levels of pollutants. The volume of rain water collected by a HASL wet/dry collector has averaged within 4% of the volume expected based on data obtained using a standard rain gauge. The deposition of Cl^?, SO ₄ ^?2 , NA⁺. Mg^?2 and K⁺ in the total collector, which is exposed continuously to the atmosphere, is about 10% greater than the deposition in the wet plus dry sides of the HASL collector.     

gamma-Radiation influences browning, antioxidant activity, and malondialdehyde level of apple juice

Apple juice was gamma-irradiated at 5 degrees C at doses ranging from 0 to 8.9 kGy and then stored at 5 degrees C for 15 days. Ionizing radiation reduced the browning of apple juice and increased antioxidant activity measured by the ferric-reducing antioxidant power (FRAP) assay. The magnitude of changes increased with radiation dose. The level of malondialdehyde (MDA) measured using the thiobarbituric acid reactive substrates assay increased at radiation doses above 2.67 kGy. The browning of irradiated juices increased during storage at 5 degrees C, but the irradiated juices were still lighter than controls at the end of storage. Differences in FRAP values disappeared during early periods of storage while higher MDA levels were observed in irradiated samples during most of the storage period. Elimination of suspended matter from apple juice did not alter irradiation-induced changes in browning, FRAP, or MDA formation. As compared to irradiation conducted at 5 and 20 degrees C, treatment at -15 degrees C was less effective in reducing browning and in increasing MDA formation but elevated FRAP values. The exclusion of oxygen from juices did not affect the reduction in browning due to irradiation but promoted the increase in FRAP values and decreased the irradiation-induced MDA formation.