Evaluation of Likelihood of Co-Occurrence of Erwinia amylovora with Mature Fruit of Winter Pear

ABSTRACT Phytosanitary concerns about fire blight prohibit export of U.S.-grown pears to some countries without this disease. To examine these concerns, we evaluated the potential for co-occurrence of Erwinia amylovora with mature, symptomless winter pear fruit by inoculation experiments and by survey of commercial orchards. Immature pear and apple fruit were inoculated in orchards with E. amylovora strain 153N as resuspended lyophilized cells or as ooze from diseased tissues. Regardless of inoculum source, population size of Ea153N on fruit declined by an order of magnitude every 3 to 4 days during the first 2 weeks after inoculation; at 56 days after inoculation, Ea153N was not detected, except on 1 of 450 fruit with 4 colony forming units (CFU). After inoculation of flowers, calyx-end survival of Ea153N on pear and apple fruit declined from high populations at petal fall to a few cells at harvest, with no detection of the pathogen after a 7-week cold storage. Migration of Ea153N into symptomless pear fruit from diseased branches was evaluated by enrichment assay and nested polymerase chain reaction of internal fruit core tissues; these assays failed to detect the pathogen in healthy fruit from diseased trees. At harvest, E. amylovora could not be detected on 5,599 of 5,600 fruit of d'Anjou pear sampled from commercial orchards in major production areas of the Pacific Northwest; one fruit yielded 32 CFU of the pathogen. Postharvest, mature pear fruit contaminated with Ea153N and subsequently wounded required a dose of >10,000 cells at the wound site to allow for persistence of the pathogen through a 7-week-cold storage. We conclude that epiphytic E. amylovora shows similar survival characteristics on both pear and apple fruit, this pathogen is not an endophyte within mature symptomless pear fruit, its presence is exceptionally rare on commercially produced fruit, and that epiphytic survival of E. amylovora through a postharvest chilling period is unlikely given the unrealistically high population size required for persistence.     

Using mixed methods to investigate factors influencing reporting of livestock diseases: A case study among smallholders in Bolivia

Livestock disease surveillance is particularly challenging in resource-scarce settings, where disease events are often unreported. Surveillance performance is determined as much by the quantifiable biological attributes of the disease, as it is by motivations and barriers perceived by livestock keepers for disease reporting. Mixed methods designs, which integrate the collection, analysis and interpretation of qualitative and quantitative data in a single study, are increasingly used across different disciplines. These designs allow for a deeper exploration of the topic under investigation, than can be achieved by either approach alone.     

Lack of Correlation Between Papillomaviral DNA in Surgical Margins and Recurrence of Equine Sarcoids

Bovine papillomavirus (BPV) types 1 (BPV-1) and 2 (BPV-2) are causally associated with the development of equine sarcoid tumors. Recurrence rates after surgical excision of sarcoids are estimated to be 30%–40%. We hypothesized that the presence of BPV DNA in histologically tumor-free surgical margins of sarcoids is associated with risk of recurrence, and increased quantity of BPV DNA is associated with increased risk of recurrence. Formalin-fixed sarcoids classified as “completely excised” histologically were obtained from two institutions. A total of 25 tumors were included, eight of which recurred within 1 year of excision. Qualitative and quantitative polymerase chain reaction (PCR) tests for detection of BPV-1 and BPV-2 were performed on neoplastic tissue and tumor-free surgical margins in formalin-fixed paraffin-embedded biopsy specimens following DNA extraction. Bovine papillomavirus-1 was found in all tumor samples and in histologically “clean” margins of 21 samples, whereas BPV-2 was found in only two tumor samples. Although quantitative PCR was more sensitive than qualitative PCR in detecting BPV DNA in surgical margins, there was no significant difference in the presence of BPV-1 or BPV-2 DNA in margins of tumors that recurred versus those that did not recur for either test. Although this study is limited by sample size, our results suggest that PCR analysis of surgical margins for BPV DNA is not a reliable method to predict equine sarcoid recurrence after resection.     

Rearing Macrobrachium rosenbergii larvae in Fiji

Rearing Macrobrachium rosenbergii larvae to post-larvae has been accomplished using simple techniques. Live Artemia nauplii, ground kai meat (Batissa violacea) and tuna (Thunnus albacores) were used as food. About 16 300 post-larvae were produced in 13 trials.     

Longer migration not necessarily the costliest strategy for migrating humpback whales

1. Long‐distance migration is a demanding physical activity, and how well animals manage the associated costs will have important implications for their fitness.
2. The Oceania humpback whale (Megaptera novaeangliae) population is recovering from past exploitation markedly slower than the neighbouring east Australian whales. The reasons for this are unknown, although higher energetic costs of longer migratory distances could be a possible explanation. Due to their fully aquatic lives, studying the energy expenditure of these large animals requires methods that do not rely on capturing the animal, such as bioenergetic models.
3. A state‐space model was fitted to satellite data to infer behavioural states for southern migrating whales. Travel speeds and behavioural states were used in a bioenergetic model to estimate the energetic cost of the migration phase. Relative differences in average duration, distance, and energetic costs were compared between migratory routes and distances.
4. Total energy used during migration was a trade‐off between cost of transport (determined by travel speed) and daily maintenance (determined by daily basal metabolic costs). Oceania whales migrating to the Amundsen and Bellingshausen Seas travelled fastest and furthest, 15 and 21% further than whales migrating to the d'Urville Sea (east Australian whales) and Ross Sea, respectively. Therefore, they had the highest cost of transport, 25 and 85% higher than for d'Urville Sea and Ross Sea whales, respectively. However, energy saved in terms of daily maintenance by using fewer days to complete a longer migration resulted in only a 6–7% increase in total energetic cost.
5. The results highlight that travelling further does not necessarily translate into an increase in total energy expenditure for migratory whales, since they can compensate for longer distance by travelling faster. Further research on the energetics of different whale populations could provide insight into the productivity of Southern Ocean feeding regions and help understand the environmental and anthropogenic effects on the whales' energy budgets.

     

Terrestrial ecosystem processes of Victoria Land, Antarctica

Terrestrial environments of Victoria Land, Antarctica are ideal systems to test hypotheses about the sensitivity of ecosystem processes to climate variability, and the relationships between soil biodiversity and ecosystem functioning because of their high sensitivity to climate change and their limited diversity. This region is also considered among the most pristine of ecosystems, and therefore may serve as an indicator for detecting the response of other ecosystems to global environmental change. Rates and controls over key ecosystem processes remain poorly documented over much of Victoria Land, but it is generally held that the distribution and functioning of soil communities are most limited by the availability of liquid water and organic carbon. Here we review examples of ecosystem processes from several sites in North and South Victoria Land and develop a regional synthesis accounting for variation in the availability of soil resources (i.e. liquid water, organic matter, inorganic nutrients). Variation in soil microclimate, organic matter, moisture and salinity encountered over gradients of coastal to interior sites, latitude, and soil chronosequences are the primary controls over the structure of soil communities and their functioning. Imbalanced stoichiometric nutrient ratios frequently encountered in Victoria Land ecosystems also contribute to limited distribution of soil biota, and where they occur these elemental imbalances indicate lower biological activity and little biotic control over bulk element ratios in soils. Priorities and future directions of Victoria Land soil and ecosystem research are also discussed.     

Simultaneous and sensitive detection of three foodborne pathogens by multiplex PCR, capillary gel electrophoresis, and laser-induced fluorescence

The simultaneous detection of Staphylococcus aureus, Listeria monocytogenes, and Salmonella spp. has been approached by a new multiplex PCR-based procedure followed by capillary gel electrophoresis with laser-induced fluorescence detection (multiplex-PCR-CGE-LIF). As compared to slab gel electrophoresis, the use of CGE-LIF improved from 10- to 1000-fold the sensitivity of the multiplex PCR analysis, allowing the detection of 2.6 x 10(3) cfu mL(-1) of S. aureus, 570 cfu mL(-1) of L. monocytogenes, and 790 cfu mL(-1) of Salmonella in artificially inoculated food, without enrichment. Following 6 h of enrichment, as low as 260, 79, and 57 cfu mL(-1) of S. aureus, L. monocytogenes, and Salmonella, respectively, were detected. The CGE-LIF method is shown to be reproducible, providing relative standard deviation (RSD) values lower than 0.8% for analysis time and lower than 5.8% for peak areas. The multiplex-PCR-CGE-LIF proved a powerful analytical tool to detect various food pathogens simultaneously in a fast, reproducible, and sensitive way.