Comparative effects of auxin transport inhibitors on rhizogenesis and mycorrhizal establishment of spruce seedlings inoculated with Laccaria bicolor

We compared the effects of two auxin transport inhibitors (2,3,5-triiodobenzoic acid (TIBA) and 1-N-naphthylphthalamic acid (NPA)) on rhizogenesis and mycorrhizal establishment of Picea abies L. (Karst.) seedlings inoculated with Laccaria bicolor S238N (Maire) Orton. Inoculation of seedlings with L. bicolor under in vitro conditions strongly increased host root and shoot growth. Although TIBA had no effect on taproot growth, NPA decreased taproot growth and deformed the root apex into a globular shape in both non-inoculated seedlings and seedlings inoculated with L. bicolor. Inoculation with L. bicolor strongly increased lateral rhizogenesis of the seedlings, and application of 100 microM indole-3-acetic acid (IAA) partially reproduced this effect. Although TIBA completely inhibited the stimulatory effect of L. bicolor on lateral root formation, NPA inhibited it only partially. Both TIBA and NPA counteracted the effect of exogenous IAA on lateral rhizogenesis. Inoculation with L. bicolor significantly increased shoot growth and seedling dry biomass, whereas application of exogenous IAA had no effect on either parameter. There was no effect of NPA on shoot growth and biomass production. The presence of TIBA completely prevented the development of ectomycorrhizal structures (mantle and Hartig net). In the presence of NPA, the number of seedlings colonized by the fungus was reduced and the degree of development of ectomycorrhizal structures was variable, but not completely prevented. In medium lacking tryptophan, neither TIBA nor NPA inhibited the release of IAA produced by L. bicolor in pure culture. When 100 microM tryptophan was added to the medium, TIBA significantly increased the amount of IAA released by the fungus, whereas NPA had no significant effect. We conclude that fungal IAA plays an important role in plant rhizogenesis and in the establishment of ectomycorrhizal symbiosis.     

Persistence of a biocontrol strain of Phlebiopsis gigantea in conifer stumps and its effects on within‐species genetic diversity

Fungal isolations and genetic fingerprinting were used to determine whether Phlebiopsis gigantea stump treatment against Heterobasidion annosum sl. using a single genotype (Rotstop) would affect the genetic diversity of P. gigantea populations. The survival time of P. gigantea was longer in Norway spruce (Picea abies) stumps compared to Scots pine (Pinus sylvestris) as no isolates were obtained from pine stumps 6 years after treatment, whereas in about half of the spruce stumps the fungus was still present. The usage of Rotstop did not seem to increase the occurrence of the fungus 5 years after the treatment in fresh (1‐year‐old) untreated stumps within the same forest stands. All the isolates from the 6‐year‐old treated spruce stumps were identical in genotype with the Rotstop‐strain, whereas all isolates from the fresh untreated spruce and pine stumps differed from it. Within the treated pine stand, the biocontrol usage seemed to have caused a slight reduction in genetic markers not related to Rotstop, but there were no statistically significant differences between the marker frequencies and the local natural population. Thus, Rotstop is not likely to cause any immediate threat to the genetic diversity of P. gigantea.     

The impact of medetomidine on the protein‐binding characteristics of MK‐467 in canine plasma

This study determined the unbound fraction of the peripheral α₂‐adrenoceptor antagonist MK‐467 alone and combined with medetomidine. MK‐467 (0.1, 1 and 10 μm ) was incubated in canine plasma with and without medetomidine (molar ratio 20:1), with human serum albumin (HSA) and with α1‐acid glycoprotein (AGP). Rapid equilibrium dialysis was used for the measurement of protein binding. All samples were analysed by liquid chromatography and tandem mass spectrometry to obtain the unbound fraction (f_u) of MK‐467. Unbound fractions (f_u) of MK‐467 in canine plasma (mean ± standard deviation) were 27.6 ± 3.5%, 26.6 ± 0.9% and 42.4 ± 1.2% at 0.1, 1.0 and 10 μm concentrations, respectively. In the presence of medetomidine, f_u were 27.5 ± 0.4%, 26.6 ± 0.9% and 41.0 ± 2.4%. The f_u of MK‐467 in HSA were 50.1 ± 2.5% at 0.1 μm , 49.4 ± 1.2% at 1.0 μm and 56.7 ± 0.5% at 10 μm . f_u of MK‐467 in AGP was 56.3 ± 3.7% at 0.1 μm , 54.6 ± 5.6% at 1.0 μm and 65.3 ± 0.4% at 10 μm . Protein binding of MK‐467 was approximately 70% between 0.1 and 1.0 μm . Medetomidine had no apparent effect on the protein binding of MK‐467.     

Plasma concentration and cardiovascular effects of intramuscular medetomidine combined with three doses of the peripheral alpha2-antagonist MK-467 in dogs

Objective

We investigated the plasma concentrations and cardiovascular effects of intramuscularly (IM) administered medetomidine, administered alone or with three different doses of MK-467.

Reversal of medetomidine-induced cardiovascular and respiratory changes with atipamezole in dogs

The effects of atipamezole, an alpha 2-antagonist, on six medetomidine-sedated laboratory beagles were studied in a randomised complete block design. The dogs were sedated with medetomidine (20, 40 or 80 micrograms/kg intramuscularly) and five- and 10-fold larger doses of atipamezole were administered intramuscularly 30 minutes later. Atipamezole significantly increased the medetomidine-depressed heart rate, respiratory frequency and arterial Po2. The drug also transiently decreased the mean arterial blood pressure but subsequently the blood pressure of the treated group did not differ from that of a group of dogs treated with a placebo.     

Effect of anaesthesia on contrast-enhanced ultrasound of the feline spleen

The spleens of 18 healthy cats were imaged using contrast-enhanced ultrasound (CEUS) to evaluate splenic perfusion and to compare perfusion patterns in awake and anaesthetised cats. Two groups of cats were imaged; the first (Group 1) consisted of 10 young, anaesthetised cats and the second (Group 2) comprised eight young to middle aged cats that were initially imaged when awake and later following anaesthesia. A two-phase enhancement of the spleen was observed both in awake and in anaesthetised cats. The time to first appearance of the contrast was significantly faster in awake (3.9±0.6s) than anaesthetised (4.8±1.0s) cats in Group 2 (P=0.031). A marked heterogeneous perfusion pattern was more prevalent in the anaesthetised (50%) compared to the awake (12.5%) animals in Group 2. The spleen was heterogeneous for approximately 30s in all groups. The results indicated that CEUS suspected focal perfusion defects of the spleen, especially during general anaesthesia, should be evaluated with caution and only after the initial heterogeneity has disappeared.     

Effects of different doses of L-659'066 on the bispectral index and clinical sedation in dogs treated with dexmedetomidine

ObjectiveTo evaluate the effects of three doses of L-659’066 (MK-467) on the bispectral index (BIS) and clinical sedation in dexmedetomidine-sedated Beagles.Study designRandomized, experimental cross over study.AnimalsEight purpose-bred healthy laboratory Beagles.MethodsDexmedetomidine (10 μg kg^?1 IV [DEX]) was administered alone or in combination with three doses of L-659’066 (250 μg kg^?1 [DL250]; 500 μg kg^?1 [DL500] and 750 μg kg^?1 [DL750] IV) in the same syringe in a randomized crossover manner. The bispectral index (BIS), electromyography (EMG) and sedation score were recorded at baseline and 5, 10, 20, 30, 45 and 60 minutes after treatment.ResultsWhen compared to DEX, BIS and EMG were significantly higher and the sedation score significantly lower with DL500 and DL750. With DEX, BIS was significantly decreased at times 20, 30 and 60 minutes whereas the sedation scores were significantly increased at all time points after drug administration in all groups. Bioequivalence for clinical sedation was detected between DEX and all doses of L-659’066, reaching European Medicines Agency (EMA) standards.Conclusions and clinical relevanceAlthough L-659’066 interfered with dexmedetomidine induced sedation, the degree of the reduction was not clinically relevant. Despite performing better when dexmedetomidine was used alone, BIS did not reflect the clinical sedative status when the antagonist was added.     

Intervertebral disc disease in Dachshunds radiographically screened for intervertebral disc calcifications

Background

Intervertebral disc disease (IDD) is a very common neurological disease, Dachshunds being the breed most often affected. In this breed, IDD has a hereditary background and is associated with intervertebral disc calcification (IDC), an indicator of severe intervertebral disc degeneration. In Finland, spinal radiography is used, when screening for IDC before breeding Dachshunds. We evaluated the association between IDC and IDD in Finnish Dachshunds radiographically screened for IDC.A questionnaire was sent to owners of 193 radiographically screened Dachshunds aged at least ten years. Clinical signs indicative of IDD were compared with IDC grade (grade 0 = no calcifications, grade 1 = 1 – 2 calcifications, grade 2 = 3 – 4 calcifications and grade 3 = 5 or more calcifications) and with age at the time of the radiographic examination. The diagnosis of IDD was confirmed by a veterinarian.

Results

IDD was common in the study population with 31% of dogs being affected. IDD and IDC were clearly connected (P < 0.001); IDD was rare in dogs with no calcifications (grade 0) and common in dogs with severe IDC (grade 3). The IDC grade was strongly positively associated with frequency of back pain periods (P < 0.001), and dogs with IDC grade 3 had frequent periods of pain. Reluctance to jump onto a sofa had a strong positive association with back pain. No association existed between age of the dog at the time of the radiographic examination and clinical signs indicative of IDD.

Conclusions

Radiographically detected IDC and IDD are common in Finnish Dachshunds and are strongly associated with one another. Spinal radiography is an appropriate screening tool for breeders attempting to diminish IDC and IDD in Dachshunds. A breeding program that screens dogs and selects against IDC can be expected to reduce the occurrence of IDD in future. Twenty-four to 48 months of age is a suitable age for screening.

Electronic supplementary material

The online version of this article (doi:10.1186/s13028-014-0089-4) contains supplementary material, which is available to authorized users.     

Viruses of Heterobasidion parviporum persist within their fungal host during passage through the alimentary tract of Hylobius abietis

Heterobasidion annosum (Fr.) Bref. sensu lato is an important fungal parasite of coniferous trees throughout the temperate regions of the world. Approximately 15% of Heterobasidion isolates are infected by dsRNA viruses, which are considered as obligately intracellular and transmit vertically into both basidiospores and asexual conidia. Insects such as H. abietis and its larvae feeding on wood colonized by Heterobasidion fungi may carry Heterobasidion conidia and hyphae. In this study, we used H. abietis as a model species to reveal whether Heterobasidion viruses resist in their fungal host passing through the digestive tract of insects that may potentially serve as disseminators of fungal propagules. Pinus sylvestris branches were inoculated by three different strains of Heterobasidion parviporum, hosting taxonomically diverse virus species: Heterobasidion RNA virus 2, HetRV4 and HetRV6. Then, the inoculated branches were fed to H. abietis insects, and beetle excrements were investigated for Heterobasidion infections. All the inoculated fungal strains survived passage through the alimentary tract of the insects (survival rate 25–80%). The passage rates of the viruses inside their hosts varied considerably, ranging from 0 to 67%. Two different mycoviruses, HetRV2 and HetRV6, survived the intestinal passage of their fungal host, while the virus species HetRV4 was detected among none of the five H. parviporum isolates retrieved from insect faeces. The relative stability of fungi harbouring viruses suggests that if viruses are to be used for biological control against Heterobasidion species, it is likely that insect feeding does not considerably decrease the virus effect, but might instead enhance short‐range dispersal of the viral biocontrol agent.     

Feed Consumption and Efficiency in Paternal Progeny Groups in Mink

Abstract

A total of 730 dark mink, half of each sex, representing 94 paternal progeny groups originating from 16 farms were housed on a test station from about 10 weeks of age until pelting. Average daily feed consumption in paternal progeny groups was registered daily. Individual body weights were recorded five times. Feed consumption, feed efficiency and weight gain in paternal progeny groups were calculated in four subperiods corresponding to the times of weighing. These traits, body weights and length of pelts were analysed for differences between paternal progeny groups and farms of origin. A considerable difference between farms of origin and paternal progeny groups was found for most traits, indicating genetic variation. Correlations between averages of paternal progeny groups were calculated, and interpreted as approximations to genetic correlations. Feed consumption was highly correlated across periods. Feed efficiency showed low to medium correlations between periods. A favourable correlation was found between efficiency of weight gain and efficiency of longitudinal growth.