Experimental enteric infection of gnotobiotic piglets with a Chlamydia psittaci strain of avian origin

The pathogenicity of a Chlamydia psittaci isolate of pigeon origin was assessed using a litter of gnotobiotic piglets. At 3 days of age, six piglets were inoculated intragastrically with egg-grown chlamydiae, the remaining six pigs were sham-inoculated. The animals were observed for clinical signs, and they were killed and necropsied sequentially between 4 and 15 days of age. Clinical manifestations consisted of slight softening of the faeces between 6 and 10 days post-inoculation (DPI). Immunohistochemistry revealed chlamydial replication predominantly in the small intestine, initially within villous enterocytes, after 4 DPI mostly in the lamina propria. Histopathology showed villous atrophy and increased numbers of inflammatory cells in the gut up to 6 DPI. Chlamydial stages of normal morphology were identified within enterocytes using transmission electron microscopy. An enzyme-linked immunosorbent assay (ELISA) run on faecal samples revealed shedding of chlamydial antigen from 3 until 11 DPI. Systemic dissemination of Chlamydia occurred to a limited extent according to polymerase chain reaction and immunohistochemistry results of several extraintestinal organs. Corresponding histopathological changes were minimal. Sera of all pigs were negative for anti-chlamydial antibodies using a complement fixation test. In conclusion, inoculation of this isolate in gnotobiotic piglets resulted in a productive enteric infection with mild lesions, weak systemic dissemination, and faecal shedding, indicating the pig as a potential host for avian chlamydiae.     

Fire-free natural regeneration in water limited Pinus halepensis forests: a silvicultural approach

We aimed to elucidate environmental and silvicultural factors that determine the extent of fire-free natural regeneration in east Mediterranean Pinus halepensis forests. The specific aims were to study the potential and identify bottlenecks for natural regeneration and examine the effects of overstory thinning and site preparation treatments. We integrated four experiments conducted in diverse ecoregions in Israel ranging from semiarid to subhumid. Seedling emergence and survival were traced for 2–4 years in Mishmar Ha’Emek Forest (MHF) with annual rainfall of 604 mm; Shaharia Forest (SF)—435 mm; and Yatir Forest (YF)—280 mm. Effects of thinning treatments: clearcut, 100 tree, 200 tree ha^?1 and control—310 tree ha^?1, were examined in MHF. Effects of site preparation treatments: soil scarification and herb clipping were examined in SF. Density of emerged seedlings varied among ecoregions and was linked to average annual rainfall. Within ecoregions, emerged seedling density was higher on north-facing slopes than on south-facing slopes and was strongly related to stand characteristics (e.g., stem basal area) and seed rain. Seedling survival rate of about 20 % was recorded in MHF while no seedling survival was observed in YF and SF during the study years. Thinning treatments reduced seed rain and emerging seedling density, but increased seedling survival and growth. Recruitment 4 years after thinning was highest in the 100 tree ha^?1 treatment and lowest in the control. In SF, seedling survival was limited mainly by herbaceous vegetation and was improved by soil scarification and herb clipping. Silvicultural implications are discussed.     

Metabolic and clinical traits in horses undergoing feed deprivation for elective orthopaedic surgery

The objective of this study was to investigate some metabolic and clinical effects of feed deprivation in horses that were submitted for orthopaedic surgery. The effects of preoperative feed restriction were investigated in 20 horses submitted for elective orthopaedic surgery.The patients were fasted from 12 hours before until 4 hours after surgery. Serum free amino acids, glucose,free fatty acids (FFA), white blood cell counts, creatine kinase (CK) and aspartate aminotransferase (AST) were determined 24 hours before surgery, 2 hours after the end of anaesthesia and 24 and 72 hours after surgery. Besides, abdominal sounds, appetite, faecal quality and body temperature were examined. Serum free amino acids did not react homogenously, concentrations were partly increasing or decreasing. Plasma glucose and FFA increased after surgery and returned to their preoperative levels 72 hours after surgery. A significant rise of the segmented granulocytes occurred 24 hours after surgery, all other parameters of the leukogram did not exceed the physiological range. AST reached its highest activity 24 hours after surgery, whereas CK activities were highest at 2 hours after surgery. Abdominal sounds were significantly reduced until 24 hours after surgery, however, appetite was not depressed. Faecal quality was physiological after surgery. Mean body temperature stayed within the physiological range. In conclusion, a relatively short perioperative fasting period had significant effects on the metabolic traits in horses, however the effects on physiological functions were minor. The consequences of major surgical procedures need to be addressed in future studies.     

CSF from a puppy with a cerebral vascular hamartoma

A 9-week-old puppy with refractory seizures and a dome-shaped head presented to the Mississippi State College of Veterinary Medicine Specialty Center for suspected hydrocephalus. Computerized tomography (CT) findings included transtentorial herniation and an intra-axial mass with dystrophic mineralization. Cerebrospinal fluid analysis revealed an increased nucleated cell count of 1100/μl (RI < 5/μl), erythrocyte count of 2.2 × 10⁶/μl, and markedly increased microprotein of 1939 mg/dl (RI < 30 mg/dl). On cytologic examination of the CSF, numerous erythrophagocytic, and hemosiderin-laden macrophages were observed, which indicated chronic active hemorrhage. Many neutrophils, macrophages, and lymphocytes that contained numerous intracytoplasmic, pleomorphic, bright yellow crystals were observed. Considering the ongoing hemorrhage, the crystals were presumed to be hematoidin. A biopsy with histopathology was performed on the intra-axial mass, and the results were consistent with a vascular hamartoma. We speculate that the formation of these crystals was related to the ongoing hemorrhage associated with the vascular hamartoma. Identification of these crystals may be useful to aid in the identification of chronic hemorrhage associated with vascular malformations or lesions within the central nervous system.     

Characterisation of Czech arable weed communities according to management and production area considering the prevalence of herbicide-resistant species

Herbicide resistance is a widespread issue that impacts management of conventional farms, but also has ramifications for the weed community assembly; it is therefore important to see how these species factor into the weed community assembly of farms throughout the countryside. This research analysed species richness and community diversity in 98 field relevés from 48 organic and 50 conventional farms evenly distributed between two major production regions of the Czech Republic and then evaluated the incidence of species which have been reported resistant in the Czech Republic and its neighbouring countries. Farms were selected independently of any acknowledged resistant species. Out of 164 species found in this survey, only eight species have had herbicide-resistant biotypes reported in the Czech Republic, while a total of 19 species had herbicide-resistant biotypes reported in neighbouring countries. Species with recorded resistance to PSII inhibitors in the Czech Republic tended to be found together and were mostly associated with the beet production region, characterised by low altitude: Amaranthus retroflexus, Chenopodium album, Echinochloa crus-galli and Solanum nigrum. Species with reported resistance to ALS and ACCase-inhibiting herbicides were not clearly associated with a particular region or farming type. Of the species which have had reported herbicide resistance in the neighbouring countries, several were found in conventional fields within the growing season and we recommend immediate screening for herbicide resistance in these species and more diligent action in management according to anti-resistance strategies: Bromus sterilis resistant to ACCase-inhibiting herbicides, A. retroflexus resistant to ALS-inhibiting herbicides or Avena fatua resistant to ACCase and ALS-inhibiting herbicides. This work is unique in that it is evaluating weed species diversity in organic and conventional farms and using the context to frame the prevalence of high-risk herbicide-resistant species; thereby putting the potential incidence of herbicide resistance into perspective at the landscape level.     

The effect of combining linseed oil and sesamin on the fatty acid composition in white muscle and on expression of lipid-related genes in white muscle and liver of rainbow trout (Oncorhynchus mykiss)

Sesamin (S) is a known lipid modulator and has been shown to increase the conversion of α-linolenic acid (ALA) to docosahexaenoic acid in rainbow trout (Oncorhynchus mykiss) fed vegetable oil mixtures including linseed oil. In this study, we evaluated the effects of S supplementation in linseed oil-based diets, content of α- and γ-tocopherols, fatty acid (FA) composition, as well as the gene expression of lipid-related genes. Fish with an average weight of 36.5 g were fed different combinations of commercial linseed oil (LO), purified linseed oil triacylglycerols (TAG) with polar fraction removed and a mixed linseed-sunflower oil (6:4 v/v) (MO). S was added at 0.58 g 100^?1g feed and fed to the fish for a period of 58 days. Expression of PPARα was downregulated in white muscle of fish fed S containing diets (P < 0.05). The expression of PPARβ1A was not affected by S supplementation except where TAG oil was used. The expression of PPARβ1A declined significantly in TAG + S fed group (P < 0.05), which indicates that some minor compounds in linseed oil might suppress the effect of S on the expression of PPARβ1A. The expression of PPARγ(long) declined in LO + S and MO + S fed group (P < 0.05). The β-oxidation-related genes CPT1 and ACO were upregulated by vegetable oils compared to fish oil. S decreased percentage of ALA in white muscle of fish fed LO + S (P < 0.05). The increased desaturation index and the decreased ALA levels suggest that S may increase the biosynthesis of highly unsaturated FA in rainbow trout.     

Controlled reproduction in Anguilla anguilla (L.): comparison between spontaneous spawning and stripping‐insemination approaches

This study aimed to compare the fertility of eggs between artificially matured female silver eels that spawned spontaneously and those that were spawned by manual stripping. The effects of the two methods of spawning on ovulation and fertilization rate were also investigated. For this purpose, 18 wild female European eels captured in Bonello lagoon (North Adriatic Sea) were carp pituitary extract‐injected to undergo sexual maturation and ovulation; a final injection of 17,20β‐dihydroxy‐4‐pregnen‐3‐one (DHP) was administered when at least 30% of the oocytes were fully transparent. After the DHP‐injection, nine eels were transferred to a new closed recirculating aquaculture system, where they were housed with spermiating males (sex ratio 4/1) to allow spontaneous spawning (SPT‐group); the remaining nine eels were transferred to a 250 L tank and ovulation was checked at four‐hourly intervals by manual stripping (STR‐group). The number of eggs per female in the SPT‐group was significantly greater than that in the STR‐group. Furthermore, fertilization rates in the SPT‐group were notably higher than those observed in the STR‐group. Significantly, the best performances were obtained among eels in which at least 50% of oocytes were fully transparent at the time DHP was administered. We conclude that the fertility of eggs from spontaneously spawning eels is superior to that of eggs acquired by strip‐spawning and artificial fertilization.     

Utilisation of mucilage C by microbial communities under drought

Root mucilage modulates soil-plant-water dynamics, but its interactions with microbial community functioning remain poorly understood. The aims of this study were to estimate (I) the impacts of mucilage and soil water content on the microbial community composition and (II) the mucilage consumption by individual microbial groups. C4 root mucilage from maize (at 40 and 200 μg C per gram dry soil, corresponding to 10 and 50% of soil microbial biomass, respectively) was added in single pulses to a C3 soil at two moisture levels: optimum (80% of water-holding capacity (WHC)) and drought (30% of WHC). After 15 days of incubation, the microbial community composition was studied by phospholipid fatty acids (PLFA) analysis and incorporation of mucilage-derived ¹³C into individual microbial groups was determined by compound-specific isotope analysis. Microbial community composition remained largely unaffected by mucilage addition but was affected by moisture. Whereas an increase in water content reduced mucilage ¹³C recovery in PLFA for the low-dose mucilage amendment from 19 to 9%, it had no effect under the high-dose amendment (11–12%). This suggests that the role of mucilage for microbial functioning is especially pronounced under drought conditions. The fungal PLFA 18:2ω6,9 was present only under drought conditions, and fungi profited in their mucilage C utilisation from the lower competitiveness of many bacterial groups under drought. In this study, Gram-negatives (G?, characterised by PLFA 18:1ω9c, 18:1ω7c, 16:1ω7c and cy17:0) showed the highest mucilage-derived ¹³C in PLFA, especially at the high-dose amendment, suggesting them to be the major decomposers of mucilage, especially when the availability of this C source is high. Gram-positives (G+) included different sub-groups with distinct responses to moisture: G+ 1 (a15:0) were only competitive for mucilage C under drought, whereas G+ 3 (i17:0) were only able to utilise mucilage-derived C under optimal moisture conditions. During the 15-day incubation, they built up more than 40% of their membranes from mucilage-derived C, suggesting that in the case of high availability, mucilage can act as an important C source for this microbial group. However, under drought, G? 1 and fungi were incorporating the most mucilage C into their membranes (approx. 20% of PLFA-C). The observation that, for some groups, the high-dose mucilage amendments under drought led to higher ¹³C incorporation into PLFA than under optimum moisture suggests that mucilage can compensate drought effects for particular microbial groups. Thus, mucilage may not only act as a C source for microorganisms but may also mitigate drought effects for specific rhizosphere microbial groups.     

Biopore history determines the microbial community composition in subsoil hotspots

Biopores are hotspots of nutrient mobilisation and shortcuts for carbon (C) into subsoils. C processing relies on microbial community composition, which remains unexplored in subsoil biopores. Phospholipid fatty acids (PLFAs; markers for living microbial groups) and amino sugars (microbial necromass markers) were extracted from two subsoil depths (45–75 cm ; 75–105 cm) and three biopore types: (I) drilosphere of Lumbricus terrestris L., (II) 2-year-old root biopores and (III) 1.5-year-old root biopores plus six 6 months of L. terrestris activities. Biopore C contents were at least 2.5 times higher than in bulk soil, causing 26–35 times higher Σ PLFAs g^-1 soil. The highest Σ PLFAs were found in both earthworm biopore types; thus, the highest soil organic matter and nutrient turnover were assumed. Σ PLFAs was 33% lower in root pores than in earthworm pores. The treatment affected the microbial community composition more strongly than soil depth, hinting to similar C quality in biopores: Gram-positives including actinobacteria were more abundant in root pores than in earthworm pores, probably due to lower C bioavailability in the former. Both earthworm pore types featured fresh litter input, promoting growth of Gram-negatives and fungi. Earthworms in root pores shifted the composition of the microbial community heavily and turned root pores into earthworm pores within 6 months. Only recent communities were affected and they reflect a strong heterogeneity of microbial activity and functions in subsoil hotspots, whereas biopore-specific necromass accumulation from different microbial groups was absent.