Effect of antioxidants on oxidative stability of edible fats and oils: thermogravimetric analysis

Thermogravimetric analysis was used to determine the oxidative stability of various edible oils (olive oil, milkfat) and triacylglycerides (triolein, trilinolein), while the effect of natural (alpha-tocopherol, ascorbic acid) and synthetic antioxidants (butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), and tertiary butyl hydroquinone were evaluated by addition to trilinolein. Oil resistance to oxidation was obtained by measuring the increase in sample weight due to the uptake of molecular oxygen, the temperature at maximum sample weight, and the temperature at the onset of oxidation. When comparing sample weight increase, trilinolein proved to be oxidatively less stable than triolein, olive oil, and milk fat, while triolein was less stable than olive oil and milk fat. Olive oil showed significantly higher stability than milkfat when comparing the temperature at the onset of oxidation. When comparing effectiveness of antioxidants, a combination of 0.01% BHA and 0.01% BHT increased trilinolein stability the most.     

Efficacy of methyl iodide and synergy with chloropicrin for control of fungi

Efficacy of soil fumigation with methyl bromide and methyl iodide against Botrytis cinerea, Colletotrichum gloeosporioides, Fusarium oxysporum, Gliocladium virens, Phytophthora citricola, Phytophthora citrophthora, Pythium ultimum, Rhizoctonia solani and Verticillium dahliae was determined in laboratory experiments in closed fumigation chambers. Pythium ultimum was the most sensitive fungal species with EC₅₀ values for methyl bromide and methyl iodide of 15.5 and 8.6 µM , respectively. R solani was the least sensitive with EC₅₀ values of 253.4 and 161.4 µM for methyl bromide and methyl iodide, respectively. Relative potency ([methyl bromide]/[methyl iodide]) values ranged from 5.2 for P citricola to 1.5 for F oxysporum. Methyl iodide was 2.7 more efficacious than methyl bromide averaged over all fungal species. Methyl bromide/chloropicrin and methyl iodide/chloropicrin applied jointly were 2.2 and 2.8 times more efficacious, respectively, against F oxysporum than when the compounds were applied singly. Combining methyl bromide and methyl iodide with chloropicrin resulted in a significant synergistic increase in activity against F oxysporum. © 2000 Society of Chemical Industry     

Control of Phytophthora species in plant stock for habitat restoration through best management practices

Emergent plant pathogens represent one of the most significant threats to biodiversity, and exotic Phytophthora species have recently emerged as a serious problem in restored habitats in California and in nurseries producing the plant stock. It is hypothesized that ‘best management practices’ prescribed through a Phytophthora Prevention Programme (PPP) could be useful in minimizing phytophthora disease incidence. To understand the magnitude of the problem and the efficacy of the PPP, plants in restoration nurseries were evaluated for (i) the Phytophthora species assemblage present in the absence of the PPP, and (ii) the effectiveness of the PPP to reduce them. Sampling included 203 plants grown in the absence of the PPP, and 294 grown implementing the PPP. Only samples collected in the absence of the PPP were Phytophthora-positive, and cumulatively yielded 55 isolates from 13 different taxa, including 1 putative interspecific hybrid genotype. There were 21 novel Phytophthora–plant species combinations. The most common Phytophthora species was P. cactorum. Four plant species had the highest disease incidence, namely: Diplacus aurantiacus (50 ± 11.2%), Heteromeles arbutifolia (33 ± 9.6%), Ceanothus thyrsiflorus (30 ± 8.4%), and Frangula californica (30 ± 8.4%). Disease incidence in nurseries after the implementation of the PPP dropped to zero (P < 0.001), and was unaffected to any significant degree by nursery differences, or plant species tested. This study identifies a large number of novel ‘plant species × Phytophthora species’ combinations, and provides for the first time strong evidence that the PPP significantly reduced Phytophthora in plant stock for habitat restoration.     

Availability of urea to autotrophic ammonia-oxidizing bacteria as related to the fate of 14C- and 15N-labeled urea added to soil

Nitrate has been found to accumulate more rapidly in soils fertilized with urea than with inorganic sources of NH₄ ⁺, despite the fact that nitrification must be preceded by hydrolytic decomposition. For acidic conditions, this finding has been attributed to limited uptake of NH₄ ⁺ by ammonium-oxidizing bacteria (also reported herein), suggesting an advantage for direct utilization of a nonionizable N substrate such as urea. If the same advantage applies to urea-C, nitrification of urea-N would also be promoted in neutral or alkaline soils, as reported in numerous studies. To ascertain whether urea-C can be utilized directly by nitrifying organisms, NO₂ ⁻ production was measured for Nitrosomonas europaea and Nitrosospira sp. NPAV in minimal media with urea as the sole source of either C or C and N. Nitrite accumulated only with the latter organism, in which case nearly quantitative recovery was observed for N added as NH₄ ⁺ and/or urea. In a subsequent study, recovery of ¹⁴C and ¹⁵N in gaseous, extractable, and hydrolyzable forms was determined after incubation with labeled urea for up to 29 days, by using two soils that differed markedly in physiochemical properties affecting nutrient availability. Results obtained in correlating ¹⁴C incorporation in the amino acid fraction with ¹⁵N accumulation as NO₃ ⁻ were consistent with the stoichiometry that would be expected if C fixation were driven by autotrophic nitrification. Our findings demonstrate unequivocally that urea is utilized as a source of C and N by nitrifying microorganisms, which may account for rapid nitrification of urea-N in soils.

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Identification of in situ 2,4-dichlorophenoxyacetic acid-degrading soil microorganisms using DNA-stable isotope probing

Stable isotope probing (SIP) was used to investigate the microorganisms responsible for degradation of the herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D) in soil samples. Soils were unamended or amended with either unlabeled 2,4-D or UL(ring) ¹³C-2,4-D. Degradation of 2,4-D was complete after 17 days, whereas little removal (11±3%) was observed in the sterile controls. Terminal restriction fragment length polymorphism (TRFLP) on soil DNA after 17 days indicated a consistent increase in the relative abundance of one fragment (217 bp in Hae III digests) in soils spiked with 2,4-D (both unlabeled and labeled samples) compared to the unamended soils. DNA extracts from labeled and unlabeled 2,4-D amended soils were subject to ultracentrifugation, fractionation of centrifuged samples, followed by TRFLP on each fraction. TRFLP profiles from ultracentrifugation fractions illustrated that the same fragment experienced an increase in buoyant density (BD) in samples spiked with ¹³C-labeled 2,4-D. This increase in DNA BD indicates the organisms represented by this fragment were responsible for uptake and degradation of the herbicide. 16S rRNA sequencing of the heavy, ¹³C-enriched fraction suggests the organisms belong to the β subdivision of Proteobacteria. Herein, SIP facilitated the identification of unique organisms degrading 2,4-D in soil without the need for isolation and provided more direct evidence for a functional role of these organisms than would have been possible with the molecular-based methods alone.     

Evaluation of dietary Natustat for control of Histomonas meleagridis in male turkeys on infected litter

Histomoniasis (histomonosis, infectious enterohepatitis, or blackhead) is a disease of turkeys on litter or range caused by the protozoan Histomonas meleagridis, a parasite of worms, primarily spread in feces, in Heterakis gallinarum (cecal worm) eggs, or in Eisenia foetida (earthworms). In this trial, Natustat (Alltech, Inc., Nicholasville, KY), a proprietary plant-derived product, was used at 1.925 kg/tonne and compared with nitarsone in male hybrid turkey diets to 42 days of age on histomonad infected litter (day 7) from broiler breeders. Infected nonsupplemented and uninfected nonsupplemented control groups were also included. Natustat and nitarsone significantly improved 28- and 42-day feed conversion ratios and lowered 28- and 35-day cecal and liver lesion scores compared with infected nonsupplemented turkeys. The body weight at 42 days was greater in the Natustat and nitarsone supplemented groups than in the infected nonsupplemented group.     

Electrodiagnostic evaluation of auditory function

This article considers the types of deafness in small animals and how electrodiagnostic testing can aid in evaluating auditory dysfunction.     

Clinical signs, underlying cause, and outcome in cats with seizures: 17 cases (1997-2002)

OBJECTIVE: To determine clinical signs, results of diagnostic testing, underlying cause, and outcome in cats with seizures. DESIGN: Retrospective study. ANIMALS: 17 cats with seizures. PROCEDURE: Only those cats in which an underlying metabolic abnormality causing the seizures had been identified, diagnostic imaging of the brain and CSF analysis had been done, or a necropsy had been performed were included. Seizures were classified as being a result of metabolic disease, symptomatic epilepsy (ie, epilepsy resulting from a structural lesion of the brain), or probably symptomatic epilepsy (ie, epilepsy without any extracranial or identifiable intracranial disease that is not suspected to be genetic in origin). RESULTS: 3 cats had seizures associated with an underlying metabolic disease (hepatic encephalopathy), 7 had symptomatic epilepsy (3 with neoplasia and 4 with meningoencephalitis), and 7 had probably symptomatic epilepsy. Six of the 7 cats with symptomatic epilepsy died or were euthanatized within 3 months after the diagnosis was made, whereas 6 of the 7 cats with probably symptomatic epilepsy survived for at least 12 months after the diagnosis was made. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that cats with probably symptomatic epilepsy may have a good long-term prognosis.     

Origin and evolution of highly pathogenic H5N1 avian influenza in Asia

Outbreaks of highly pathogenic avian influenza caused by H5N1 viruses were reported almost simultaneously in eight neighbouring Asian countries between December 2003 and January 2004, with a ninth reporting in August 2004, suggesting that the viruses had spread recently and rapidly. However, they had been detected widely in the region in domestic waterfowl and terrestrial poultry for several years before this, and the absence of widespread disease in the region before 2003, apart from localised outbreaks in the Hong Kong Special Autonomous Region (SAR), is perplexing. Possible explanations include limited virus excretion by domestic waterfowl infected with H5N1, the confusion of avian influenza with other serious endemic diseases, the unsanctioned use of vaccines, and the under-reporting of disease as a result of limited surveillance. There is some evidence that the excretion of the viruses by domestic ducks had increased by early 2004, and there is circumstantial evidence that they can be transmitted by wild birds. The migratory birds from which viruses have been isolated were usually sick or dead, suggesting that they would have had limited potential for carrying the viruses over long distances unless subclinical infections were prevalent. However, there is strong circumstantial evidence that wild birds can become infected from domestic poultry and potentially can exchange viruses when they share the same environment. Nevertheless, there is little reason to believe that wild birds have played a more significant role in spreading disease than trade through live bird markets and movement of domestic waterfowl. Asian H5N1 viruses were first detected in domestic geese in southern China in 1996. By 2000, their host range had extended to domestic ducks, which played a key role in the genesis of the 2003/04 outbreaks. The epidemic was not due to the introduction and spread of a single virus but was caused by multiple viruses which were genotypically linked to the Goose/GD/96 lineage via the haemagglutinin gene. The H5N1 viruses isolated from China, including the Hong Kong SAR, between 1999 and 2004 had a range of genotypes and considerable variability within genotypes. The rising incidence and widespread reporting of disease in 2003/04 can probably be attributed to the increasing spread of the viruses from existing reservoirs of infection in domestic waterfowl and live bird markets leading to greater environmental contamination. When countries in the region started to report disease in December 2003, others were alerted to the risk and disease surveillance and reporting improved. The H5N1 viruses have reportedly been eliminated from three of the nine countries that reported disease in 2003/04, but they could be extremely difficult to eradicate from the remaining countries, owing to the existence of populations and, possibly, production and marketing sectors, in which apparently normal birds harbour the viruses.