The fate of discarded appendicularian houses: degradation by the copepod, Microsetella norvegica, and other agents

Despite the potential importance of zooplankton in degradationof marine snow, the association of colonising zooplankton withdiscarded appendicularian houses has not been investigated innorthern areas. We sampled the vertical distributions of appendicularians,houses and potential zooplankton colonisers at two stationsin the central North Sea during late summer. In addition, grazingexperiments were performed with the copepod Microsetella norvegica,which was assumed to be the main contributor to house degradation.The results were used in (i) inverse modelling, to estimatethe factors which were significant in shaping the vertical distributionof houses and (ii) calculations to estimate potential housedegradation rates. M. Norvegica was able to feed on appendicularianhouses, with feeding rates up to 0.42 g C (g C)^–1 day^–1(0.14 µg C ind.^–1 day^–1). The model resultssuggested that the vertical distribution of houses was shapedby sinking of houses, bacterial degradation and feeding of M.norvegica and invertebrate larvae. The estimated community degradationrate by M. norvegica was low, whereas invertebrate larvae haddegradation rates close to bacterial degradation. We concludethat at the typical concentrations of M. norvegica in the NorthSea (10⁴ ind. m^–2), its role in marine snow degradationis likely to be small. Degradation by other zooplankton groups,such as invertebrate larvae, can, however, be substantial.     

A simple and flexible device to odorize large stimulation areas

This paper describes a flow dilution olfactometer which allowsthe odorization of large stimulation areas and the easy manipulationof several odorants and/or concentrations. Generation of theodorized air is performed by mixing in two steps the odor vaporcontained in Tedlar bags with a pure air stream flowing continuouslyout of a nozzle. Discrete concentration values are obtainedby using pre-adjusted needle valves to change the vapor flowsampled in the bags. This kind of olfactometer was utilizedto study odor coding in the olfactory bulbs of rats and rabbits.Five Odorants were delivered at concentrations ranging from2 x 10^-4 to 1.5 x 10^-2 of the saturated vapor pressure. Measurementsshowed that lower concentrations can be obtained by fillingthe bags with a more diluted odor vapor. Furthermore, the numberof test odorants can be increased at low cost by increasingthe number of Tedlar bags.     

Prevalence of Campylobacter spp. in a subset of intensive poultry flocks in Ireland

Aim:  The aim of this study was to investigate the prevalence of Campylobacter species in a subset of intensive poultry flocks by examining samples collected in geographically disparate areas on the island of Ireland.
Methods and Results:  Faecal, water and environmental samples were collected from the interior of poultry houses on nine farms. Three cultural methods were used for Campylobacter isolation: direct plating, enrichment culture and a recovery method for emerging Campylobacter spp. Presumptive Campylobacter isolates were confirmed using biochemical tests and further identified to species level by multiplex PCR. All flocks sampled in this study were found to be contaminated with Campylobacter at the time of sampling. Structural and air samples taken from the interior of broiler houses were also found to be Campylobacter positive. All water samples were found to be Campylobacter negative. The Campycheck method was used for the isolation of emerging Campylobacter spp.
Conclusions:  Campylobacter spp. were recovered (as contaminants) from the poultry house interior, air and environmental samples in all intensive poultry flocks surveyed.
Significance and Impact of the Study:  This study highlights the need for improved biosecurity on selected poultry farms.     

Difference in Behavior Between Responses to Forskolin and General Odorants in Turtle Vomeronasal Organ

To elucidate the signal transduction mechanisms in the turtlevomeronasal receptor neurons, the effects of forskolin, changesin mucosal Ca²⁺ concentrations and ruthenium red on the responsesof the accessory olfactory bulb to general odorants were examined.Forskolin elicited a large response, suggesting that there arecAMP-gated channels in the vomeronasal neurons. On the otherhand, the dependence of the responses to general odorants onCa²⁺ concentrations was different from that of the responseto forskolin. A large response to an odorant (n-amyl acetate)appeared after the cAMP-mediated pathway was fully desensitizedby application of 50 µM forskolin. These results suggestthat the cAMP-mediated pathway does not contribute significantlyto generation of the response to general odorants. A concentrationof 50 µM ruthenium red significantly reduced the responsesto n-amyl acetate alone and after 50 µM forskolin desensitization,suggesting that the inositol triphosphate-mediated pathway contributespartly to generation of the responses to general odorants inthe vomeronasal neurons. Chem Senses 21: 763–771, 1996.     

Effects of Ca2+ on electro-olfactogram in the isolated olfactory mucosa of the frog

Reports are conflicting as to whether the presence of Ca²⁺ onthe ciliated surface of the olfactory mucosa suppresses or potentiatesthe response of receptor cells to odorants. To resolve thisissue, electro-olfactograms (EOGs) were recorded from the isolatedolfactory mucosae of the frog while its ciliated surface wasperfused with saline solutions containing differing concentrationsof Ca²⁺. A decrease in Ca²⁺ concentration augmented the EOGamplitude, and the magnitude of the augmentation increased asthe Ca²⁺ concentration decreased progressively. The slow forskolin-inducedchange in potential likewise increased in amplitude with theremoval of Ca²⁺ from the perfusate. Desensitization of EOG duringthe prolonged administration of odorants developed similarly,irrespective of the concentration of Ca²⁺ on the ciliated surface.These observations are consistent with findings of patch-clampand biochemical experiments. The augmentation of EOG at lowCa²⁺ concentrations appeared to result from either an increasein activity of adenylate cyclase or an increase in responsivenessof the channels activated by adenosine 3',5'-cyclic monophosphate,but not from an increased sensitivity of the receptor molecules.     

Effect of aluminum sulfate on litter composition and ammonia emission in a single flock of broilers up to 42 days of age

New alternatives are necessary if the environmental impact linked to intensive poultry production is to be reduced, and different litter handling methods should be explored. Among these, acidifying amendments added to poultry litters has been suggested as a management practice to help reduce the potential environmental effect involved in multiple flock cycles. There have been several studies on the use of aluminum sulfate (alum) and its benefits, but almost no data are available under farm conditions in Europe. An experiment with Ross 308 broilers from 1 to 42 days of age was conducted to evaluate the effect of alum on litter composition, the solubility of some mineral elements and NH₃ emission during a single flock-rearing period in commercial houses located in southeast Spain. Broilers were placed on clean wood shavings in four commercial houses, containing 20 000 broilers each. Before filling, alum was applied at a rate of 0.25 kg/m² to the wood shavings of two poultry houses, whereas the remaining two were used as control. Litter from each poultry house was sampled every 3 to 5 days. Ammonia emissions from the poultry houses were monitored from 37 to 42 days of age. In comparison with the control group, alum treatment significantly reduced the pH level of the litter (P < 0.001) with an average difference of 1.32 ± 0.24 units. Alum-treated litter showed, on average, a higher electrical conductivity than the control litter (5.52 v. 3.63 dS/m). The dry matter (DM) and total N and P contents did not show differences between the treatments (P > 0.05). Regarding the NH₄⁺-N content, alum-treated litter showed a higher value than the untreated litter, with an average difference of 0.16 ± 0.07% (on a DM basis). On average, alum-treated litter had lower water-soluble P, Zn and Cu contents than the untreated litter. Alum noticeably reduced the in-house ammonia concentration (P < 0.001), with an average of 4.8 ppm at 42 days of age (62.9% lower than the control), and ammonia emissions from 37 to 42 days of age were significantly reduced by the alum treatment (P < 0.001), representing a reduction of 73.3%. The lower pH values might have reduced ammonia volatilization from the litter, with a corresponding positive effect on the building environment and poultry health. For these reasons, litter amendment with alum could be recommended as a way of reducing the pollution potential of European broiler facilities during a single flock cycle.     

Protection of olfactory responses from inhibition by ethyl bromoacetate, diethylamine, and other chemically active odorants by certain esters and other compounds

Certain vaporous chemicals (chemically active odorants) arecapable of both stimulating olfactory responses and reactingwith receptors, ion channels, or receptor/ionophore macromoleculesto inhibit olfactory responses. We have studied the physiologicaleffects of several chemically active odorants using electrophysiologicaltechniques to record electroolfactogram (EOG) responses fromthe frog's olfactory mucosa. So far, the most studied agentsare ethyl bromoacetate (EBA), an alkylating agent, and diethylamine(DEA), a compound which is one of the strongest neutral organicbases. Certain odorants, or ‘protectants’, whenpresent before, during, and after exposure of the olfactorymucosa to either EBA or DEA have the property of maintainingolfactory responses which would otherwise be inhibited by exposureto the chemically active odorant alone. Protection from inhibitionby EBA is conferred by the presence of isoamyl acetate and afew closely-related esters, while protection from inhibitionby DEA is produced by the presence of p-dichlorobenzene. Protectionfrom inhibition by DEA is also achieved by lowering the pH ofthe olfactory mucosa through the simultaneous delivery of CO₂which produces carbonic acid. The mechanism of protection byesters and p-dichlorobenzene is unknown, but it seems likelythat these odorants somehow interfere with the access of thechemically active odorant to a site where it would normallyreact. ¹Present address: PSC Box 511, Peterson AFB, Colorado Springs,Colorado 80914, USA. ²Permanent address: Department of Chemistry, New Mexico Instituteof Mining and Technology, Socorro, New Mexico 87801, USA.     

Olfactory studies using ethyl bromoacetate and other chemically active odorants

Eleven chemically active odorants were tested to determine theireffectiveness and specificity in inhibiting electroolfactogram(EOG) responses in the frog olfactory mucosa. These inhibitoryagents probably act by several different mechanisms, but theyall produced a comparable degree of inhibition when approximatelythe same amount of inhibitor had been applied. One agent, ethylbromoacetate, produced a specific pattern of inhibition in whichresponses to all odorants tested were inhibited except responsesto certain amines. A related agent, ethyl chloroacetate, produceda similar, but less well-defined specific effect. Non-specificinhibitory effects were produced by seven of the agents tested.Two agents produced no inhibition, presumably because theirlow vapor pressure prevented the application of sufficient reagentin the vapor phase. The majority of the effective inhibitorsare alkylating agents or substrates for nucleophilic additionwhich react with sulfhydryl or amino groups of proteins. Bycontrast, the inhibitory effect of diethylamine is probablythe result of its basicity. The basicity would enable neutralizationreactions with acidic groups of proteins or other substancesin the microenvironment of the receptors. Several lines of evidencelead to the conclusion that the inhibitory action of the chemicallyactive odorants is principally the result of disruption of molecularolfactory receptors in the membranes of olfactory neurons, andthat sulfhydryl, amino, and carboxyl groups are of importanceto the function of olfactory receptors, ion channels, or receptor/ionophoremacromolecules. ¹Present address: PSC Box 511, Peterson AFB, Colorado Springs,Colorado 80914, USA. ²Permanent address: Department of Chemistry, New Mexico Instituteof Mining and Technology, Socorro, New Mexico 87801, USA.     

Alkylpyrazines, volatiles formed in the Maillard reaction. I. Determination of odour detection thresholds and odour intensity functions by dynamic olfactometry

The Maillard reaction plays an important role in the formationof the aroma and flavour of many foods, especially heat-treatedfoods. Among the volatiles formed, alkylpyrazines contributeto the sensory characteristics of a great number of foods. Thisarticle presents results obtained in an investigation of theodour properties of purified, synthetic alkylpyrazines. Dynamicair-dilution olfactometers were used to present the stimulito 10 panellists. Odour detection thresholds were estimatedfor 13 alkylpyrazines. Panel results for the compounds investigatedwere in the range from 4 to 490 p.p.b. (v/v). Alkylpyrazinescontaining ethyl substituents had, in general, threshold valuesin the lower part of this range. Odour intensity functions (I= k x Cⁿ) of five alkylpyrazines were estimated by an odourintensity matching technique. n-Butanol was used as the odourintensity reference. The exponent n of the odour intensity functionsranged from 0.44 to 0.58.     

Laboratory tests for controlling poultry red mites (Dermanyssus gallinae) with predatory mites in small ‘laying hen’ cages

To assess their potential to control poultry red mites (Dermanyssus gallinae), we tested selected predaceous mites (Androlaelaps casalis and Stratiolaelaps scimitus) that occur naturally in wild bird nests or sometimes spontaneously invade poultry houses. This was done under laboratory conditions in cages, each with 2–3 laying hens, initially 300 poultry red mites and later the release of 1,000 predators. These small-scale tests were designed to prevent mite escape from the cages and they were carried out in three replicates at each of three temperature regimes: 26, 30 (constant day and night) and 33–25?°C (day-night cycle). After 6?weeks total population sizes of poultry red mites and predatory mites were assessed. For the temperature regimes of 26 and 33/25?°C S. scimitus reduced the poultry red mite population relative to the control experiments by a factor 3 and 30, respectively, and A. casalis by a factor of 18 and 55, respectively. At 30?°C the predators had less effect on red mites, with a reduction of 1.3-fold for S. scimitus and 5.6-fold for A. casalis. This possibly reflected hen manure condition or an effect of other invertebrates in the hen feed. Poultry red mite control was not negatively affected by temperatures as high as 33?°C and was always better in trials with A. casalis than in those with S. scimitus. In none of the experiments predators managed to eradicate the population of poultry red mites. This may be due to a prey refuge effect since most predatory mites were found in and around the manure tray at the bottom of the cage, whereas most poultry red mites were found higher up in the cage (i.e. on the walls, the cover, the perch, the nest box and the food box). The efficacy of applying predatory mites in the poultry industry may be promoted by reducing this refuge effect, boosting predatory mite populations using alternative prey and prolonged predator release devices. Biocontrol success, however, will strongly depend on how the poultry is housed in practice (free range, cage or aviary systems) and on which chemicals are applied to disinfect poultry houses and to control other pests.     

Influence of stimulus intensity on odour discrimination by olfactory bulb neurons as compared with receptor cells

Previously reported electrophysiological responses recordedfrom individual neurons in the olfactory bulb of frogs stimulatedwith odorous compounds were further analyzed using statisticalmethods. Five of the odorants were delivered at two concentrations.The pattern of discrimination among these odorants was investigatedwith the aid of the Pearson's correlation test and Benzecri's‘analyse des correspondances’. Special attentionwas paid to the incidence of odour concentration on this discriminationpattern. The results were compared with those of a similar studyperformed on receptor cells in the same experimental conditions.The comparison indicated that the information processing inthe olfactory bulb seems to improve discrimination between chemicallydifferent stimuli, especially those poorly discriminated byreceptor cell responses, whereas it protects this discriminationagainst a massive influence of the intensity of the stimuli.     

Litter and aerosol sampling of chicken houses for rapid detection of Salmonella typhimurium contamination using gene amplification

Rapid screening of poultry houses for contamination is critical for Salmonella control. Use of air filter sampling has great potential for efficient and reliable monitoring of Salmonella spp., as it could represent an entire poultry house and solve sample-size problems. Two sampling methods (litter and air filter) were compared for detection in four chicken pens inoculated with a S. typhimurium antibiotic resistant strain. Salmonella levels in both litter and air filter samples were determined by PCR amplification and by conventional enrichment. Although amplified DNA was not directly detected, amplified DNA could be detected using a dual probe hybridization sensor. The ratio of the positive samples to total samples determined by gene amplification was much lower than that obtained by conventional enrichments (29/128 versus 102/128 samples). However, the ratio obtained by gene amplification with air filter samples was greater than that with litter samples (26/64 versus 3/64). These results demonstrate that the air filter sampling method is an alternative method of Salmonella detection in poultry house using PCR gene amplification protocol. Journal of Industrial Microbiology & Biotechnology (2000) 24, 379–382. Received 12 August 1999/ Accepted in revised form 17 February 2000     

Odour discrimination by olfactory bulb neurons: statistical analysis of electrophysiological responses and comparison with odour discrimination by receptor cells

Electrophysiological responses of olfactory bulb neurons todifferent odorants have been presented and discussed with referenceto homologous properties of olfactory receptor cells. This paperdeals with further mathematical processings of part (experimentA) of these original data and proposes a comparison with a similarstudy performed in receptor cells, using the same odorants presentedat the same concentrations. In the olfactory bulb the patternof similarities and differences among odorants was found tobe almost the same whether the mathematical processings wereapplied to the odor-evoked discharge frequencies or to excitatoryresponses considered separately. By contrast, separate processingof inhibitory responses led to a different organization of odorantsimilarities, indicating that inhibitory responses were lessdiscriminating than excitatory responses. This was discussedin relation to the synaptic organization of the olfactory bulb.The comparison of these findings with those previously obtainedin receptor cells showed indisputable resemblances between thepatterns of discrimination among odorants at both levels ofthe olfactory pathways, especially in the grouping of some odorantsin pairs and in the overall organization of the olfactory spaceas determined by factor analysis. The findings also suggestedthat odorant discrimination was slightly improved in the olfactorybulb but no sign of a novel, specific odour categorization couldbe found.     

Salmonella in Wastes Produced at Commercial Poultry Farms

Composite samples of freshly voided excreta from 91 poultry houses were tested qualitatively for Salmonella; 26 (29%) were positive. The houses were located on 36 farms, 18 of which (50%) yielded one or more positive samples. In a separate, quantitative study, Salmonella densities ranged from less than 1 to over 34,000 per g of excreta (dry weight). High densities were noted in waste from cage houses, but not in waste from floor houses (litter or wire floors). Salmonella-shedding chickens were located in only one small area of the row of cages examined in detail. A total of 15 Salmonella serotypes were identified during the study.     

Endosymbiotic bacteria living inside the poultry red mite (Dermanyssus gallinae)

This study investigated the endosymbiotic bacteria living inside the poultry red mite collected from five samples of one commercial farm from the UK and 16 farms from France using genus-specific PCR, PCR-TTGE and DNA sequencing. Endosymbiotic bacteria are intracellular obligate organisms that can cause several phenotypic and reproductive anomalies to their host and they are found widespread living inside arthropods. The farm sampled from the UK was positive for bacteria of the genera Cardinium sp. and Spiroplasma sp. From France, 7 farms were positive for Cardinium sp., 1 farm was positive for Spiroplasma sp., 1 farm was positive for Rickettsiella sp. and 2 farms were positive for Schineria sp. However, it was not possible to detect the presence of the genus Wolbachia sp. which has been observed in other ectoparasites. This study is the first report of the presence of endosymbionts living inside the poultry red mite. The results obtained suggest that it may be possible that these bacterial endosymbionts cause biological modifications to the poultry red mite.     

New studies on odour discrimination in the frog's olfactory receptor cells. II. Mathematical analysis of electrophysiological responses

Revial et al. (1982) reported the experimental findings obtainedin cell units stimulated with two new sets of odorants. Thepresent paper deals with mathematical processing of these electrophysiologicaldata. The multidimensionality of the odour space was confirmed.Camphor, isoborneol and cineole appeared to represent a ‘camphorgroup’ markedly discriminated from other odorants. A‘terpenegroup’ including terpinene, dimethylstyrene, limoneneand cymene and related to menthane and menthene was observed.A series of 8 cycloketones was found to have a linear patternin the factorial planes and to be subdivided into three subsets.Cyclooctadecanone and cyclotetradecanone displayed correlationsand spatial relationships with musk ketone while cycloundecanone,cyclodecanone and especially cyclononanone were more relatedto the‘camphor group’. Separate processing of theunitary responses of 12 receptor cells recorded from a singlepreparation led to the building of a factorial space resemblingthat constructed with the full collection of data. The incidenceof odorant concentration on similarity evaluation is discussedon the basis of receptor responses to two different concentrationsof some of the odorants.     

House Production by Oikopleura dioica (Tunicata, Appendicularia) Under Laboratory Conditions

We examined the generation time and the house renewal rate ofOikopleura dioica under various conditions. Animals were fedtwo flagellates, Isochrysis galbana and Tetraselmis sp., withconcurrent determination of the carbon contents of body andhouse to estimate house production. The generation time was6 days at 15°C, 4 days at 20°C and 3 days at 25°Cat both 25 and 30 p.s.u. with a food concentration of 4 x 10⁴cells ml^–1. The carbon content of newly secreted housesranged from 0.5 to 0.8 µg, corresponding to 15.3 ±4.8% of body carbon. The house renewal rates increased withincreasing temperature and decreasing salinity. Food concentrationsranging from 100 to 16 x 10⁴ cells ml^–1, body size andlight condition had no effect on house renewal rate. Cloggingof the inlet filter by adding the large diatom Ditylum sol causedan increase in house renewal rates. The total number and carboncontent of houses during an animal's lifetime ranged from 46to 53 houses and from 6.5 to 10.4 µg, respectively. Sincedaily house production calculated for the O. dioica populationcorresponded to 130–290% of its biomass and daily discardedhouse materials corresponded to 490–1100% of the biomass,this organism must play an important role as a producer of macroscopicaggregates.     

Populational fluctuation and spatial distribution of Alphitobius diaperinus (Panzer) (Coleoptera; Tenebrionidae) in a poultry house, Cascavel, Parana state, Brazil.

Knowledge of the population fluctuation and spatial distribution of pests is fundamental for establishing an appropriate control method. The population fluctuation and spatial distribution of the Alphitobius diaperinus in a poultry house in Cascavel, in the state of Parana, Brazil, was studied between October, 2001 and October 2002. Larvae and adults of the lesser mealworm were sampled weekly using Arends tube traps (n = 22) for six consecutive flock grow-outs. The temperature of the litter and of the poultry house was measured at the same locations of the tube traps. Beetle numbers increased continuously throughout all the sampling dates (average 5,137 in the first week and 18,494 insects on the sixth week). Significantly greater numbers of larvae were collected than adults (1 to 20 times in 95% of the sampling points). There was no correlation between temperature and the number of larvae and adults collected, therefore no fluctuation was observed during the sampling period. The population growth was correlated to litter re-use. The highest temperatures were observed in deep litter. The spatial distribution of larvae and adults in the poultry house was heterogeneous during the whole period of evaluation. Results suggest that monitoring in poultry houses is necessary prior to adopting and evaluating control measures due to the great variability of the insect distribution in the poultry house.