Tissue culture micropropagation of Douglas-fir

A procedure was developed for plantlet production from embryos of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco]. The Medium for Conifer Morphogenesis, used at full strength, and supplemented with 10 M benzyladenine for 17 days produced an average of 6.8 shoots on more than 90% of the embryos. The percentage of shoot-forming embryos as well as the average number of shoots per embryo varied significantly among eight seedlots. For secondary multiplication, 89% of the adventitious shoots produced axillary buds on MCM with 5 M benzyladenine. However, 0.5 M BA was more suitable for the elongation of axillaries. Rooting ranged from 0–87% depending upon the treatment. The highest percentage was obtained with a 7-week incubation in peat:perlite containing 1/5-strength medium, 1% sucrose and 2.7 M naphthaleneacetic acid, followed by 5 weeks on peat:perlite with 1/5-strength major and minor salts, full iron and organics, 1% sucrose and 0.1% charcoal.     

Duration and method of fixation affects the sensitivity of a digoxygenin-labelled DNA probe in detecting Kudoa thyrsites in Atlantic salmon skeletal muscle

The effect of fixative and duration of fixation on the sensitivity of a non-radioactive in situ hybridisation (ISH) protocol to detect Kudoa thyrsites small subunit ribosomal deoxyribonucleic acid (DNA) was investigated. Strong ISH reactions were detected in 5-μm sections of paraffin-embedded Atlantic salmon muscle after fixation for 1 day in Davidson's solution (DS). Reactions were weak following 3 or 5 days fixation and absent after 17 or 28 days fixation. Strong ISH reactions were observed after 1, 3 or 5 days fixation in neutral buffered formalin (NBF). The reactions were weak after 17 days and weak to nonexistent after 28 days of fixation. Reactions were consistently strong after fixation in 95% ethanol for up to 28 days. Some mature spores reacted weakly or not at all by ISH. Parasite DNA was weakly amplified by polymerase chain reaction (PCR) from paraffin-embedded muscle after 1 day of fixation in DS but not after fixation for 3, 5, 17 or 28 days. Amplified DNA was detected after fixation in NBF for 1, 3 and 5 days, but not after 17 or 28 days. In contrast, PCR consistently amplified DNA from paraffin-embedded, ethanol-fixed muscle. Caution should be used in the choice of fixative and duration of fixation when preserving Atlantic salmon tissues for molecular diagnosis of K. thyrsites.     

Impacts of Bolbophorus damnificus (Digenea: Bolbophoridae) on Production Characteristics of Channel Catfish,Ictalurus punctatus,Raised in Experimental Ponds

Bolbophorus damnificus was recognized as a threat to channel catfish, Ictalurus punctatus, production in Louisiana and Mississippi in 1997 and 1999, respectively. Severe to moderate outbreaks (≥34% prevalence) are correlated to heavy losses, but impact of mild outbreaks with low prevalence (<33%) was unknown. Laboratory and field studies were conducted to evaluate sublethal acute (early stage) and chronic (late stage) trematode infection impacts on catfish production. Fish raised in ponds seeded with ram's horn snails from ponds harboring active B. damnificus outbreaks resulted in infection prevalence ranging from 1.6 to 20.4%. Compared to fish raised in ponds not seeded with infected snails (0% prevalence), fish biomass, number harvested, and total feed fed were significantly lower. These data agree with previous studies where mild infections reduced feed consumption, fish production, and economic returns. Infected fish were collected from ponds and used in a laboratory growth study. Once removed from the infection source, weight gain, growth rate, feed consumption, and feed efficiency were equal to or greater than trematode‐free fish. This suggests that although early B. damnificus infection (premetacercarial development) can severely impact production, infection has little impact on performance once metacercarial cysts are fully developed, and the infection source is removed.     

Determinants of the Travel Behavior of the Suburban Elderly

In recent years, a significant feature of population change in North American metropolitan areas has been the rapid suburbanization of elderly people. The ability to engage in routine activity may be a necessary condition for the maintenance of independent life styles and psychological well‐being among older suburbanites. Using a conceptual framework based on Parmelee and Lawton's ecological model of aging, this article offers an exploratory investigation of the determinants of the travel of separate samples of elderly male and female suburbanites to each of five destination categories of key service/activity sites in a Canadian city. The results of the tests of ten multiple regression models disclose that the levels of explanation of trip frequency afforded by “autonomy components” (e.g. health‐related characteristics, living arrangements, and income level) vary according to destination category. However, the explanatory power of “security components” (i.e. variables concerning access to destination categories) is generally low. Overall, the findings of the study provide a basis for developing a deeper understanding of the repetitive travel behavior of elderly suburbanites.     

Multicolor and electron microscopic imaging of connexin trafficking

Recombinant proteins containing tetracysteine tags can be successively labeled in living cells with different colors of biarsenical fluorophores so that older and younger protein molecules can be sharply distinguished by both fluorescence and electron microscopy. Here we used this approach to show that newly synthesized connexin43 was transported predominantly in 100- to 150-nanometer vesicles to the plasma membrane and incorporated at the periphery of existing gap junctions, whereas older connexins were removed from the center of the plaques into pleiomorphic vesicles of widely varying sizes. Selective imaging by correlated optical and electron microscopy of protein molecules of known ages will clarify fundamental processes of protein trafficking in situ.     

LC-MS/MS analysis of neonicotinoid insecticides in honey: methodology and residue findings in Austrian honeys

An analytical method for the simultaneous determination of residues of eight neonicotinoid insecticides and two metabolites in honey using LC-MS/MS was developed and validated. Two approaches of sample preparation were investigated, with the final method involving acetonitrile extraction and subsequent cleanup by dispersive solid-phase extraction (QuEChERS type). Validation was based on quintuplicate analysis at three fortification levels and showed satisfactory recoveries (60-114%) and high precision (RSDs between 2.7 and 12.8%). Low limits of detection and quantification could be achieved for all analytes ranging from 0.6 to 5 μg/kg and from 2 to 10 μg/kg, respectively. Investigations of Austrian honey samples revealed the presence of acetamiprid, thiacloprid, and thiamethoxam residues in honey; however, no sample exceeded the maximum residue limits. On average, flower honey samples contained neonicotinoid residues in higher quantities compared to forest honey samples.     

Ascaris suum Infection in Calves III. Pathology

Gross changes in the lungs of Ascaris suum- infected calves consisted of atelectasis and hemorrhagic foci, edema and emphysema, frequently with bullae. Prominent microscopic lung lesions were edema and emphysema of the interlobular septa with large numbers of eosinophils within and around lymphatics, peribronchiolar lymphoid nodules and parasitic granulomas. Many of the microscopic features were consistent with those found in atypical interstitial pneumonia. Changes in the alveoli were atelectasis, the exudation of plasma proteins, mononuclear cells and eosinophils, and alveolar wall thickening. Lesions found later included fibrosis and fetalization of the alveolar walls. Plasma cells and neutrophils were not common. Challenge with Toxocara canis after sensitization with A. suum resulted in the lungs developing a few areas of atelectasis. Migration of T. canis to lungs of calves is slower than A. suum. A. suum larvae were always found in bronchi, bronchioles and alveoli of calves that died. Lesions were observed in the liver but not the kidney of A. suum infected calves; both lung and liver lesions tended to resolve with time.     

Ascaris suum Infection in Calves I. Clinical Signs

Clinical signs consistent with those of atypical interstitial pneumonia (AIP) were induced in calves sensitized with infective Ascaris suum eggs at seven to 20 weeks of age and challenged at three-week intervals one or more times. These signs usually appeared on the sixth or seventh day postinfection and reached maximum severity between the tenth and 13th days following infection. Prominent signs were: dyspnea, often with expiratory grunt, coughing, mouth breathing and emphysema as well as increased respiration and heart rates. In general, the intensity of signs was dependent upon dose size, although a single small dose resulted in acute signs and death in one calf. Intermittent coughing and vesicular sounds were induced in calves given A. suum eggs continually over prolonged periods. No respiratory abnormalities resulted from challenge with Toxocara canis after sensitization with A. suum. Antihistamine therapy did not alter the clinical signs in A. suum infected calves.     

Proliferative renal myxosporidiosis in spawning coho salmon (Oncorhynchus kisutch) in British Columbia and Washington

An unidentified myxosporean parasite (CKX) is described from the kidney of approximately 80% of spawning coho salmon Oncorhynchus kisutch (Walbaum) in British Columbia, Canada and Washington, United States of America. Morphological features were described using light and electron microscopy. Sequencing of polymerase chain reaction (PCR) amplified 18S ribosomal RNA gene and in situ hybridisation were used to further characterise CKX. The parasite occurred with a focal distribution within tubule epithelial cells, the tubule lumen and the interstitium as primary cells containing from one to at least 16 secondary cells. Luminal stages were degenerate and sporogony was not observed. In situ hybridisation using a digoxygenin-labelled DNA probe confirmed CKX to be the source of DNA used in PCR analyses. CKX 18S rDNA sequences were most similar (97%) to those of Sphaerospora oncorhynchi. Phylogenetic analysis revealed similarities among the 18S rDNA sequences of CKX, S. oncorhynchi and Myxidium lieberkuehni. CKX is hypothesised to be the abortive extrasporogonic development of a Sphaerospora sp. or Myxidium sp. occurring in immune-incompetent spawning and senescent salmon.