An Overview of Canadian Research Activities on Diseases Caused by Phytophthora ramorum: Results, Progress, and Challenges.

International trade and travel are the driving forces behind the spread of invasive plant pathogens around the world, and human-mediated movement of plants and plant products is now generally accepted as the primary mode of their introduction, resulting in huge disturbance to ecosystems and severe socio-economic impact. These problems are exacerbated under the present conditions of rapid climatic change. We report an overview of the Canadian research activities on Phytophthora ramorum. Since the first discovery and subsequent eradication of P. ramorum on infected ornamentals in nurseries in Vancouver, British Columbia, in 2003, a research team of Canadian government scientists representing the Canadian Forest Service, Canadian Food Inspection Agency, and Agriculture and Agri-Food Canada worked together over a 10-year period and have significantly contributed to many aspects of research and risk assessment on this pathogen. The overall objectives of the Canadian research efforts were to gain a better understanding of the molecular diagnostics of P. ramorum, its biology, host-pathogen interactions, and management options. With this information, it was possible to develop pest risk assessments and evaluate the environmental and economic impact and future research needs and challenges relevant to P. ramorum and other emerging forest Phytophthora spp.

First Report of Puccinia graminis f. sp. tritici Races with Virulence to Wheat Stem Rust Resistance Genes Sr31 and Sr24 in Eritrea.

Wheat stem rust, caused by Puccinia graminis f. sp. tritici, has historically been a major limiting factor in wheat production. Identification of isolate Ug99 in Uganda in 1999 highlighted the vulnerability of a large proportion of the global wheat crop and raised international concerns. Since initial detection, seven races have been identified in the Ug99 lineage and occurrence has been confirmed in nine countries (4). During rust surveys of Eritrea undertaken in October 2010, stem rust was found to be widespread throughout the highland wheat-growing areas. Presence of P. graminis f. sp. tritici was recorded in 95% of the 92 cereal fields surveyed, with high disease severity (>40%) recorded at 50 sites. Collected stem rust samples were analyzed for race identity in a level 3 biocontainment laboratory in Canada. Nine collections yielded viable spores for infection studies. Virulence analysis with 20 differentials in the letter-code nomenclature system (1) identified two races from repeated experiments; TTKST (four confirmed isolates) and PTKST (five confirmed isolates). Both races belong to the Ug99 lineage and both exhibit combined Sr31 and Sr24 virulence. TTKST and PTKST differ only in their virulence or avirulence to Sr21, respectively. This first confirmation of TTKST and PTKST in Eritrea is important because it represents further geographical spread of Ug99-related races. Since first detection of a Sr24 variant of Ug99 (race TTKST) in Kenya in 2006 (1), these variants have become the predominant P. graminis f. sp. tritici pathotypes in most of eastern Africa. Race TTKST caused epidemics in Kenya in 2007, and race PTKST was first detected in Ethiopia the same year (T. Fetch, unpublished data). Recent detection of race PTKST in three additional southern Africa countries (South Africa, Zimbabwe, and Mozambique [2,3]) indicates on-going range expansion within the African continent. Sr24-virulent variants of Ug99 are a cause for concern since a high frequency of cultivars from South America, Australia, the United States, and the CIMMYT are known to possess the Sr24 resistance gene. On the basis of observed occurrence and postulated migration routes of the original Ug99 (race TTKSK), the confirmed presence of TTKST and PTKST in Eritrea increases the possibility for range expansion out of Africa by crossing the Red Sea and into the Arabian Peninsula. Future spread of TTKST and PTKST to western Asia is considered highly likely. References: (1) Y. Jin et al. Plant Dis. 92:923, 2008. (2) F. Mukoyi et al. Plant Dis. 95:1188, 2011. (3) Z. A. Pretorius et al. Plant Dis. 94:784, 2010. (4) R. P. Singh et al. Annu. Rev. Phytopathol. 49:465, 2011.

Characterization of chicken Sertoli cells in vitro.

In the testis, Sertoli cells play a key physiological role in that they support, nourish, and protect germ cells. Because of the importance of Sertoli cells, several laboratories have established a culture system of Sertoli cells. These cultures have been well developed in mammalian species, but to our knowledge no purified avian Sertoli cells culture has been described. The aim of this study was to isolate avian Sertoli cells and to investigate their function using a chicken model in an in vitro test system. Immature chicken Sertoli cells in culture present morphology similar to that of mammalian cells and conserve expression of the specific Sertoli marker, anti-Müllerian hormone. Furthermore, in contrast to mammals, they express the 3ß-hydroxysteroid dehydrogenase enzyme. Stimulation of Sertoli cells with ovine follicle-stimulating hormone rapidly activates the 3 main downstream signaling pathways of the follicle-stimulating hormone receptor: cyclic( )adenosine monophosphate/protein kinase A, phosphatidylinositol 3-kinase/Akt, and mitogen-activated protein kinase pathways. In vitro, Sertoli cells are able to secrete lactate and inhibin and have conserved the phagocytosis property. Finally, avian Sertoli cells present 3 interesting characteristics: they actively proliferate in vitro, can be passaged several times, and are suitable for freezing in nitrogen. A direct consequence of these properties is to use this cell culture test system as an alternative method to bird reprotoxicity studies.

Molecular Detection of Phytophthora ramorum by Real-Time Polymerase Chain Reaction Using TaqMan, SYBR Green, and Molecular Beacons.

ABSTRACT Sudden oak death, caused by Phytophthora ramorum, is a severe disease that affects many species of trees and shrubs. This pathogen is spreading rapidly and quarantine measures are currently in place to prevent dissemination to areas that were previously free of the pathogen. Molecular assays that rapidly detect and identify P. ramorum frequently fail to reliably distinguish between P. ramorum and closely related species. To overcome this problem and to provide additional assays to increase confidence, internal transcribed spacer (ITS), beta-tubulin, and elicitin gene regions were sequenced and searched for polymorphisms in a collection of Phytophthora spp. Three different reporter technologies were compared: molecular beacons, TaqMan, and SYBR Green. The assays differentiated P. ramorum from the 65 species of Phytophthora tested. The assays developed were also used with DNA extracts from 48 infected and uninfected plant samples. All environmental samples from which P. ramorum was isolated by PARP-V8 were detected using all three real-time PCR assays. However, 24% of the samples yielded positive real-time PCR assays but no P. ramorum cultures, but sequence analysis of the coxI and II spacer region confirmed the presence of the pathogen in most samples. The assays based on detection of the ITS and elicitin regions using TaqMan tended to have lower cycle threshold values than those using beta-tubulin and seemed to be more sensitive.

Timing associated with oviductal sperm storage and release after artificial insemination in domestic hens.

Female birds store sperm in sperm storage tubules (SSTs) in the uterovaginal junction of their reproductive tract for days or weeks (depending on species) before fertilization. Sperm are transported from the SSTs to the infundibulum where fertilization occurs immediately after ovulation of each ovum. The timing of sperm release from the SSTs relative to ovulation is unknown for any bird. Here, we show that, after artificial insemination of domestic fowl Gallus domesticus, sperm are not accepted into any region of the oviduct before sexual maturity. Once hens reach maturity, there is a temporal shift in the distribution of sperm throughout the oviduct. Sperm are first accepted into and accumulate in the SSTs 6 to 8 days before ovulation but are at this point significantly less numerous in the infundibulum. From 1 to 6 days before ovulation, approximately 10-fold more sperm (235 × 10(3) sperm) populate the infundibulum than at 6 to 8 days before ovulation (26 × 10(3) sperm; P < 0.001). Our results suggest that the mechanisms underlying sperm acceptance and release in the oviduct are under fine temporal control, most likely mediated by female hormones.

Acute modulation of aged human memory by pharmacological manipulation of glucocorticoids.

In a previous longitudinal study of basal cortisol levels and cognitive function in humans, we showed that elderly humans with 4- to 7-yr cumulative exposure to high levels of cortisol present memory impairments, compared with elderly humans with moderate cortisol levels over years. Here, we measured whether memory performance in two groups of elderly humans separated on the basis of their cortisol history over a 5-yr period could be modulated by a hormone-replacement protocol in which we inhibited cortisol secretion by the administration of metyrapone and then restored baseline cortisol levels by infusion of hydrocortisone. We showed that in elderly subjects with a 5-yr history of moderate cortisol levels (n = 8), metyrapone treatment significantly impaired memory performance, a deficit that was reversed following hydrocortisone replacement. In the elderly subjects with a 5-yr history of high cortisol levels and current memory deficits (n = 9), metyrapone treatment did not have any significant effect on memory performance, but hydrocortisone treatment significantly decreased delayed memory. These results suggest that memory function in elderly humans can be intensely modulated by pharmacological manipulation of glucocorticoids, although the direction of these effects depends on the cortisol history of each individual.

Increased cortisol levels and impaired cognition in human aging: implication for depression and dementia in later life.

Perhaps the most prominent feature of human aging is the variability in decline of intellectual processes. Although many research avenues have been used to study the origin of such an increased variability with aging, new studies show that some biological factors may be associated with normal and pathological cognitive aging. One biological parameter that came under scrutiny in the past few years is the hypothalamic-pituitary-adrenal (HPA) axis, an endocrine closed-loop system controlling the secretion of stress hormones (glucocorticoids). In this review, we summarize data obtained in both animals and humans suggesting that cumulative exposure to high levels of glucocorticoids can be particularly detrimental for the aged hippocampus, a brain structure involved in learning and memory in both animals and humans. We then analyze the implication of these data for the study of dementia and depression in later life, two disorders characterized by increased glucocorticoid secretion in a significant proportion of patients. Finally, we suggest various factors that could explain the development of glucocorticoid hypersecretion in later life.

First Report of Leaf and Stem Rust Caused by Puccinia sherardiana on Sphaeralcea grossulariaefolia in North America and S. munroana in Wyoming.

Diseased samples of globe mallow, Sphaeralcea grossulariaefolia and S. munroana, were submitted by an ornamental seed producer in Wyoming to our Extension Plant Pathology Laboratory in July 1997. Dark brown, amphigenous telia surrounded by chlorotic halos were present on both foliage and stems. Mean teliospore dimensions observed were 30.8 × 44.8 µm. The teliospores germinated readily on water agar at 20°C and formed basidiospores within 24 h. Aecia and uredinia were not found. Based on characteristics mentioned above, this fungus was identified as Puccinia sherardiana Körn (1). This microcyclic rust was previously described on 12 other Sphaeralcea spp. plus other plant species in the Malvaceae family (1,2). Stem and foliar symptoms were reproduced in a greenhouse on 8-week-old plants of S. grossulariaefolia and S. munroana. These plants were inoculated with teliospores removed from the original diseased plant material. Immediately after inoculation, plants were misted and placed in plastic bags and incubated for 36 h at 100% relative humidity and 20°C. Plants continued growth with natural lighting and with day and night temperatures of 20 and 15°C, respectively. Symptoms developed within 12 days with initial telia rupturing the host epidermis 13 days after inoculation. Telia were examined microscopically to complete Koch's postulates. References: (1) J. C. Arthur. Manual of Plant Rusts in United States and Canada. Hafner Pub., 1962. (2) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. American Phytopatholical Society, St. Paul, MN, 1989.

Treatment of ventilator-associated pneumonia with piperacillin-tazobactam/amikacin versus ceftazidime/amikacin: a multicenter, randomized controlled trial. VAP Study Group.

In a randomized trial conducted in 27 intensive care units, we compared the clinical efficacy and safety of piperacillin-tazobactam (TAZ; 4 g/0.5 g q.i.d.) and of ceftazidime (CAZ; 1 g q.i.d.), both combined with amikacin (7.5 mg/kg b.i.d.), as therapy for ventilator-associated pneumonia (VAP; acquired after > or =48 hours of mechanical ventilation). VAP was diagnosed with use of protected samples and quantitative cultures, and outcome was assessed blindly from treatment. Of 204 patients suspected of having VAP and randomized to a treatment arm of the study, 127 (64%) had bacteriologically confirmed infections, of which 37% were polymicrobial and 32% involved Pseudomonas aeruginosa; 115 patients (51 TAZ and 64 CAZ recipients) remained evaluable as per protocol. Clinical/bacteriologic cure rates (TAZ vs. CAZ, 51% vs. 36%; 95% confidence interval of difference, -0.2% to 30.2%), and 28-day mortality rates (16% vs. 20%) were similar; however, fewer bacteriologic failures occurred with TAZ (33% vs. 51%; P = .05). We conclude that the two regimens were of equivalent clinical efficacy in therapy for confirmed VAP.

[Nutritional management of neonates and infants with cystic fibrosis of the pancreas detected at birth]. / Prise en charge nutritionnelle des nouveau-nés et nourrissons atteints de fibrose kystique du pancréas et dépistés à la naissance.

From a systematic neonatal screening for cystic fibrosis in the Basse-Normandie area and to prevent disorders of the intestinal transit related to malabsorption, neonates then infants were given a semi-elemental hypercaloric diet, with supplements in nitrogen, MCT, minerals, vitamins and low in LCT. Diets were adjusted every month during a consultation using clinical and biological parameters. Results in the first 14 children showed that clinically as well as biologically, these children may remain within the normal range, avoiding the previously reported growth retardation and mineral or vitamin deficiencies. This procedure should allow an improvement in the quality of life and prognosis of such children, by maintaining adequate nutritional status.

[Human "pancreatic" bladder. Two case reports]. / Vésicule "pancréatique" chez l'homme. A propos de deux observations.

The aim of this study is to report two similar cases with an "accessory biliary duct" confluent to the main pancreatic duct. There was pancreatic juice inside the "gallbladder". There was no connection between "accessory biliary duct" and intra or extrahepatic biliary ducts. This anomalous junction of the "cystic duct" and the main pancreatic duct may be explained by embryology. These two cases could be the first human "pancreatic" bladders reported.