Occurrence of Piscirickettsiosis-like syndrome in tilapia in the continental United States.

From 2001 to 2003, tilapia (Oreochromis sp.) farms in Florida, California, and South Carolina experienced epizootics of a systemic disease causing mortality. The fish exhibited lethargy, occasional exophthalmia, and skin petechia. The gills were often necrotic, with a patchy white and red appearance. Grossly, the spleen and kidneys were granular with whitish irregular nodules throughout. Granulomatous infiltrates were observed in kidney, spleen, testes, and ovary tissues, but not in the liver. The granulomas contained pleomorphic coccoid bacteria, measuring 0.57 +/- 0.1 x 0.8 +/- 0.2 microm, that were Giemsa-positive, acid-fast-negative, and Gram-negative. The bacteria had a double cell wall, variable electron-dense and -lucent areas, and were present in the cytoplasm and within phagolysosomes. The syndrome was associated with cold stress and poor water conditions. These findings are consistent with an infectious process caused by a Piscirickettsia-like bacterium described previously in tilapia in Taiwan and Hawaii. This report involves the first identified cases of a piscirickettsiosis-like syndrome affecting tilapia in the continental United States.     

Performance and nutrient dynamics of holm oak (<Emphasis Type="Italic">Quercus ilex</Emphasis> L.) seedlings in relation to nursery nutrient loading and post-transplant fertility

Holm oak (Quercus ilex L.) seedlings were exponentially (E) nutrient loaded using incremental increases in fertilizer addition or conventionally (C) fertilized using a constant fertilizer rate during nursery culture. The fertility treatments (mg N plant⁻¹) were control (0), 25E, 100E, and 100C. Subsequently, 1-year-old plants were transplanted under simulated soil fertility gradients in a greenhouse to evaluate effects of nutrient loading and post-transplant fertility on seedling performance. Post-transplant fertility consisted of fertilizing plants at two rates (0 vs. 200 mg N plant⁻¹). A water-soluble fertilizer 20-20-20 was supplied in both nursery and post-transplant experiments. Nutrient loading increased plant N content by 73% in 100E and by 75% in 100C relative to controls, although no significant differences were detected between constant and exponential fertilization regimes at the 100 mg N plant⁻¹ rate. When transplanted, nutrient loading promoted post-transplant root growth relative to shoot, implicating potential to confer competitive advantage to loaded holm oak seedlings after trans-planting. In contrast, post-transplant fertility increased new shoot dry mass by 140% as well as N, P and K content relative to controls. Results suggest that holm oak seedlings can be successfully nutrient loaded in the nursery at higher fertility rates, improving its potential to extend new roots, but alternative fertilization regimes and schedules that better fit nutrient availability to the growth rhythm and conservative strategy of this species must be tested.     

The increasing risk of Lyme disease in Canada

There is an increasing risk of Lyme disease in Canada due to range expansion of the tick vector, Ixodes scapularis. The objectives of this article are to i) raise public awareness with the help of veterinarians on the emerging and expanding risk of Lyme disease across Canada, ii) review the key clinical features of Lyme disease in dogs, and iii) provide recommendations for veterinarians on the management of Lyme disease in dogs.     

Association of Potato Psyllid (<Emphasis Type="Italic">Bactericera cockerelli</Emphasis>; Hemiptera: Triozidae) with <Emphasis Type="Italic">Lycium</Emphasis> spp. (Solanaceae) in Potato Growing Regions of Washington,Idaho, and Oregon

Potato psyllid, Bactericera cockerelli (?ulc), causes economic damage to potato crops throughout the major potato growing regions of western North America. When cultivated crops are not available, potato psyllid often occurs on non-crop hosts. In the southern U.S. and northern Mexico, native species of Lycium (Solanaceae) are important non-crop hosts for the psyllid. We determined whether Old World species of Lycium now widespread in the Pacific Northwest are reservoirs of potato psyllid in this growing region. We examined Lycium spp. across a wide geographic region in Washington, Oregon, and Idaho at irregular intervals during three growing seasons. Potato psyllids were present at all locations. To determine whether Lycium is also a host during intervals of the year in which the potato crop is not available, we monitored a subset of these sites over the entire year. Six sites were monitored at 1- to 3-week intervals from June 2014 to June 2016. Psyllids were present on Lycium throughout the year at all sites, including during winter, indicating that Lycium is also a host when the potato crop is seasonally not available. Psyllid populations included a mixture of Northwestern and Western haplotypes. We observed well-defined spring and fall peaks in adult numbers, with peaks separated by long intervals in which psyllid numbers were very low. Seasonal patterns in psyllid numbers on these non-native Lycium hosts were very similar to what has been observed on native Lycium in the desert southwest region of the U.S. Our findings demonstrate that potato psyllid associates with Lycium across a broad geographic region within the Pacific Northwest. These results will assist in predicting sources of potato psyllid colonizing potatoes in this important growing region.     

Yield, yield components and plant architecture in the F3 generation of common bean (Phaseolus vulgaris L.) derived from a cross between the determinate cultivar ‘Prelude’ and an indeterminate landrace

Growth trials were conducted outdoors in the UK to determine the yield, yield components and plant architectural differences between determinate and indeterminate Phaseolus vulgaris bean plants. F3 lines derived from crosses between ‘Prelude’, a determinate cultivar and ‘V8’, an indeterminate landrace, were grown together with the parents and ‘Carioca’, an indeterminate landrace from Brazil. Data were recorded on flowering date, number of nodes on main stem at flowering, plant height at maturity, number of pods/plant, number of seeds/pod, number of seeds/plant, 100-seed weight, seed mass/plant, percentages of diseased and healthy seeds/plant. Determinate F3 lines had significantly lower (P < 0.05) seed mass/plant, fewer pods/plant, fewer seeds/pod, fewer seeds/plant, lower harvest index, shorter stems, earlier date of flowering, fewer nodes at flowering and fewer healthy seeds/plant than indeterminate F3 lines. However, determinate genotypes had significantly larger (P < 0.05) pods to accommodate their larger seeds compared with indeterminate lines. A similar situation was found when the yield and yield components of ‘V8’, ‘Prelude’ and ‘Carioca’ were evaluated; the highest seed mass/plant was given by ‘V8’ and the lowest by ‘Prelude’. Furthermore, some indeterminate genotypes with Type IV growth habit yielded significantly higher (P < 0.05) than the high-yielding parent, ‘V8’, indicating a positive influence on seed yield by crossing different genotypes.     

Evaluation of head-out constant volume body plethysmography for measurement of specific airway resistance in conscious, sedated sheep

OBJECTIVE: To evaluate the use of a modified whole body plethysmograph in awake sheep. ANIMALS: 10 healthy adult sheep. PROCEDURE: Concurrent measurements of specific airway resistance (sR(aw)) and pulmonary resistance (R(L)) were obtained using a novel noninvasive head-out constant-volume plethysmograph and esophageal balloon-pneumotachography, respectively. All data were collected before and after external resistive loading with 1 and 5.6 cm H2O/L/s. Functional residual capacity (FRC) was measured by helium dilution for computation of airway resistance (R(aw)) preloading (R(aw) = sR(aw)/FRC). RESULTS: The sR(aw) and R(L) were closely correlated in 10 adult sheep. Additionally, sR(aw), and R(L) accurately reflected the magnitude of added resistance. The mean FRC was 52 mL/kg and used to calculate R(aw). At baseline, the values for R(aw) were significantly correlated with sR(aw) and R(L). CONCLUSIONS AND CLINICAL RELEVANCE: Precise measurements of sR(aw) and R(aw) at baseline and sR(aw) after external resistive loading were obtained by use of this novel noninvasive plethysmographic technology. This method should have application to veterinary patients or animals used in research in which noninvasive rapid or serial measurements of sR(aw) in the conscious state are required.     

Antibacterial Activity of Long-Chain Polyunsaturated Fatty Acids against Propionibacterium acnes and Staphylococcus aureus

New compounds are needed to treat acne and superficial infections caused by Propionibacterium acnes and Staphylococcus aureus due to the reduced effectiveness of agents used at present. Long-chain polyunsaturated fatty acids (LC-PUFAs) are attracting attention as potential new topical treatments for Gram-positive infections due to their antimicrobial potency and anti-inflammatory properties. This present study aimed to investigate the antimicrobial effects of six LC-PUFAs against P. acnes and S. aureus to evaluate their potential to treat infections caused by these pathogens. Minimum inhibitory concentrations were determined against P. acnes and S. aureus, and the LC-PUFAs were found to inhibit bacterial growth at 32–1024 mg/L. Generally, P. acnes was more susceptible to the growth inhibitory actions of LC-PUFAs, but these compounds were bactericidal only for S. aureus. This is the first report of antibacterial activity attributed to 15-hydroxyeicosapentaenoic acid (15-OHEPA) and 15-hydroxyeicosatrienoic acid (HETrE), while the anti-P. acnes effects of the six LC-PUFAs used herein are novel observations. During exposure to the LC-PUFAs, S. aureus cells were killed within 15–30 min. Checkerboard assays demonstrated that the LC-PUFAs did not antagonise the antimicrobial potency of clinical agents used presently against P. acnes and S. aureus. However, importantly, synergistic interactions against S. aureus were detected for combinations of benzoyl peroxide with 15-OHEPA, dihomo-γ-linolenic acid (DGLA) and HETrE; and neomycin with 15-OHEPA, DGLA, eicosapentaenoic acid, γ-linolenic acid and HETrE. In conclusion, LC-PUFAs warrant further evaluation as possible new agents to treat skin infections caused by P. acnes and S. aureus, especially in synergistic combinations with antimicrobial agents already used clinically.