The effect of temperature and moisture on the source of N<Subscript>2</Subscript>O and contributions from ammonia oxidizers in an agricultural soil

In recent years, identification of the microbial sources responsible for soil N₂O production has substantially advanced with the development of isotope enrichment techniques, selective inhibitors, mathematical models and the discoveries of specific N-cycling functional genes. However, little information is available to effectively quantify the N₂O produced from different microbial pathways (e.g. nitrification and denitrification). Here, a ¹⁵N-tracing incubation experiment was conducted under controlled laboratory conditions (50, 70 and 85% water-filled pore space (WFPS) at 25 and 35 °C). Nitrification was the main contributor to N₂O production. At 50, 70 and 85% WFPS, nitrification contributed 87, 80 and 53% of total N₂O production, respectively, at 25 °C, and 86, 74 and 33% at 35 °C. The proportion of nitrified N as N₂O (P _N2O) increased with temperature and moisture, except for 85% WFPS, when P _N2O was lower at 35 °C than at 25 °C. Ammonia-oxidizing archaea (AOA) were the dominant ammonia oxidizers, but both AOA and ammonia-oxidizing bacteria (AOB) were related to N₂O emitted from nitrification. AOA and AOB abundance was significantly influenced by soil moisture, more so than temperature, and decreased with increasing moisture content. These findings can be used to develop better models for simulating N₂O from nitrification to inform soil management practises for improving N use efficiency.     

Ecological and histopathological aspects of Didymodiclinus sp. (Trematoda: Didymozoidae) parasite of the dusky grouper,Epinephelus marginatus (Osteichthyes: Serranidae), from the western Mediterranean Sea

The dusky grouper Epinephelus marginatus (Lowe) is an ecologically and commercially important fish species of the Atlantic and Mediterranean coastal rocky habitats. Despite records of didymozoid infections in several grouper species, the identification and pathogenesis of these parasites in E. marginatus are lacking. The aim of this study is to characterize the didymozoids of E. marginatus, particularly their mechanisms of infection and histopathological features. Dusky groupers (n = 205) were caught off Majorca Island (western Mediterranean Sea) and examined for parasites. Of the fish sampled, 45% were infected with white and yellow didymozoid capsules and brown nodules, found on the gills and pseudobranchs. Parasite abundance had a strong positive relationship with the fish length; only fish larger than 20 cm were infected, suggesting infection via consumption of an intermediate host, for which E. marginatus size was a limiting factor. The capsules contained two convoluted viable adult trematodes, identified as Didymodiclinus sp., in close contact with host capillary vessels, with no evidence of the tissue inflammatory response. Conversely, nodules containing degraded parasites were surrounded by an intense inflammatory infiltrate. The findings suggest that Didymodiclinus sp. have the potential to evade the host's immune system by inhibiting the inflammatory response.     

COMPUTED TOMOGRAPHIC FEATURES OF INCISOR PSEUDO‐ODONTOMAS IN PRAIRIE DOGS (CYNOMYS LUDOVICIANUS)

Maxillary incisor pseudo‐odontomas are common in pet prairie dogs and can cause progressive respiratory obstruction, while mandibular pseudo‐odontomas are rarely clinically significant. The aim of this retrospective cross‐sectional study was to describe CT features of maxillary and mandibular incisor pseudo‐odontomas vs. normal incisors in a group of pet prairie dogs. All pet prairie dogs with head CT scans acquired during the period of 2013–2015 were included. A veterinary radiologist who was aware of final diagnosis reviewed CT scans and recorded qualitative features of affected and normal incisors. Mean density values for the pulp cavity and palatal and buccal dentin were also recorded. A total of 16 prairie dogs were sampled (12 normal maxillary incisors, 20 confirmed maxillary incisor pseudo‐odontomas, 20 normal mandibular incisors, 12 presumed mandibular incisor pseudo‐odontomas). Maxillary incisors with confirmed pseudo‐odontomas had a significantly hyperattenuating pulp and dentin in the reserve crown and apical zone, when compared to normal maxillary incisors. Pseudo‐odontomas appeared as enlargements of the apical zone with a globular/multilobular hyperattenuating mass formation haphazardly arranged, encroaching on midline and growing caudally and ventrally. Presumed mandibular incisor pseudo‐odontomas had similar CT characteristics. In 60% of prairie dogs with maxillary incisor pseudo‐odontomas, the hard palate was deformed and the mass bulged into the oral cavity causing loss of the palatine bone. The common nasal meatus was partially or totally obliterated in 81.8% of prairie dogs with maxillary pseudo‐odontomas. Findings supported the use of CT for characterizing extent of involvement and surgical planning in prairie dogs with pseudo‐odontomas.     

ULTRASONOGRAPHIC FEATURES OF GRASS AWN MIGRATION IN THE DOG

The aim of this study was to describe the ultrasonographic features of grass awns in soft tissue. A 10 MHz linear transducer was used. Ultrasound images from 25 dogs (27 awns) were collected and compared with the results from water bath studies using wild oat seeds (Avena spp.) collected in the field. Wild oat seeds were the most common grass awn found in soft tissue of dogs. Ultrasonographically grass awns appeared as a double/triple spindle-shaped echogenic interface within soft tissue. The same appearance was observed in water bath studies. In four dogs, the grass awn was removed surgically with a clamp introduced into a fistulous tract, using sonographic guidance. The grass awn was not found surgically in only three dogs, suggesting more attention during surgery. Ultrasonography is a useful diagnostic imaging technique to identify grass awns within soft tissue.     

Quenching analysis in poplar clones exposed to ozone

Effects of ozone (O(3)) on photo-inhibition of photosynthesis were investigated in two poplar clones (Populus deltoides Bartr. ex Marsh. x maximowiczii A. Henry clone Eridano, O(3)-sensitive, and P. x euramericana (Dode) Guinier clone I-214, O(3)-resistant) by using pulse amplitude modulation chlorophyll fluorescence. After a 15-day exposure to O(3) at 60 nl l(-1) for 5 h day(-1), the effective photosynthetic quantum yield of photosystem II (PSII), as indicated by the ratio of variable to maximum chlorophyll fluorescence, significantly declined in both young and mature leaves of the two clones. Compared with control samples, mature leaves of both clones showed differences in fluorescence quenching and quantum yield of PSII when exposed to ozone fumigation. We conclude that photo-inhibition is caused by transformation of active reaction centers to photochemically inactive centers that dissipate excitation energy into heat, thus causing non-photochemical fluorescence quenching. The changes observed in chlorophyll a fluorescence of O(3)-treated young leaves in both clones are consistent with O(3) having a negligible effect on photosynthetic performance, but inducing a premature decrease in chlorophyll a concentration. A possible role of O(3) pollution on chlorophyll fluorescence yield is discussed.     

Prevalence of hereditary diseases in three-year-old horses of the Freiberger breed

The objective of this study was to investigate clinical signs indicating diseases with known or suspected hereditary components like equine sarcoid, insect bite hypersensitivity, osteochondrosis, allergic airway diseases, podotrochleosis, prognatism and wind-sucking in the franches-montagnes horse.We performed a clinical examination on 702 three-year-old, privately owned franches-montagnes horses, which were shown at the Swiss-Field-Tests in 2004.With the help of the owners a questionnaire on health, environment and feeding habits of the animals was completed. In 11.9% of the horses, sarcoids were detected, 6.2% carried one tumor and 5.7% had several. The prevalence was higher in chestnuts (16.6%) than in bays (10.1%). The prevalence of sarcoids in offspring from sires with known sarcoids (data from Station-Tests 1994-2005) was not significantly higher than in descendants from stallions without a known history of sarcoids. Clinical signs of insect bite hypersensitivity were only found in six horses (0.9%). In 12.0% hoof abnormalities like brittle horn, ring hoofs or hoof cracks of different degrees were recorded. The angle between hoof base and hoof wall was 56.7 +/- 0.1 degrees, the average hoof width was 13.7 +/- 0.3 cm in the front feet. For both of these measures we found no significant difference between left and right feet. With the exception of a high sarcoid prevalence, our results indicate that the franches-montagnes horse is a healthy breed overall.     

Microbial dynamics in Mediterranean Moder humus

There is a growing interest in the links between humus forms and soil biota, and little is known about these links in Mediterranean ecosystems. Culture-independent techniques, such as DNA extraction followed by DGGE and enzyme activities, allowed us to compare microbial communities in two horizons of a forest soil in different seasonal conditions. Direct in situ lysis was applied for extraction of DNA from soil; intracellular DNA was separated from extracellular and used to represent the composition of microflora. The aims were to describe how biochemical and microbiological parameters correlate with topsoil properties in typical Mediterranean Moder humus. Changes in bacterial and fungal community composition were evident from DGGE profiles. Degrees of similarity and clustering correlation coefficients showed that the seasonal conditions may affect the composition and activity of bacterial and fungal communities in the OH horizon, while in the E horizon the two communities were hardly modified. In the same season, OH and E horizons showed a different composition of bacterial and fungal communities and different enzyme activities, suggesting similar behaviour of eubacteria and fungi relatively to all the variables analysed. Evidently, different organic carbon content in soil horizons influenced microflora composition and microbial activities involved in the P and N cycles.