Queen pheromone blocks aversive learning in young worker bees

Queen mandibular pheromone (QMP) has profound effects on dopamine signaling in the brain of young worker honey bees. As dopamine in insects has been strongly implicated in aversive learning, we examined QMP's impact on associative olfactory learning in bees. We found that QMP blocks aversive learning in young workers, but leaves appetitive learning intact. We postulate that QMP's effects on aversive learning enhance the likelihood that young workers remain in close contact with their queen by preventing them from forming an aversion to their mother's pheromone bouquet. The results provide an interesting twist to a story of success and survival.     

Network‐based approaches for soil health research and extension programming in North Dakota,USA

Farmer adoption of practices to build soil health can be enhanced using a knowledge network supported by programs and resources that incorporate technical, social and experiential learning pathways. University Extension plays a critical role in building and supporting the knowledge network by serving as (a) a boundary organization to create space for conversations to occur, (b) network manager to facilitate learning and (c) builder of social capital to encourage trust in the network. The North Dakota State University (NDSU) Soil Health Program was used to illustrate the above approach. Between 2014 and 2016, 32 informal discussion groups, called Soil Health Café Talks, reached 156 individuals. A knowledge network of all participants was developed using NodeXL. The 10 most influential individuals in the network included two scientists, five farmers, one crop consultant and two Extension specialists. All non‐NDSU participants received an evaluation form. Respondents increased their frequency of discussing cover crops with other individuals and increased sharing equipment across farming operations (i.e., vertical tillage implements and no‐till drills). Of the topics discussed, over 25% of respondents adopted practices using cover crops (interseeding and using cover crops for weed control and adjusting rotations to incorporate cover crops) as a result of attending Café Talks. Respondents also increased their use of NDSU Soil Health online resources such as Twitter (22%), YouTube (23%) and the web page (21%) as follow‐up information to Café Talks. Network‐based approaches have proven to be successful in encouraging on‐farm adoption of soil health‐building practices.     

The genetic dissection of immune response using gene-expression studies and genome mapping

Functional genomics has been applied to the genetic dissection of immune response in different ways: (1) experimental crosses between lines that differ in their (non-) specific immune response have been used to detect quantitative trait loci (QTL) underlying these differences. (2) The measurement of gene expression levels for thousands of genes using microarrays or oligonucleotide chips to identify differential expression with regard to antigen challenge: (a) before and after infection, (b) resistant versus susceptible lines, or (c) combinations of both. Interpretation of QTL results is hampered by the fact that confidence regions of the QTL are large and can contain hundreds of potential candidate genes for the QTL. At the same time, the microarray experiments tend to show large numbers of differentially expressed genes without identifying the relationships between these genes. In the recently proposed 'genetical genomics' framework, members of a segregating population are characterised for genome-wide molecular markers and for gene expression levels. This facilitates the mapping of expression-QTL (eQTL): loci in the genome that control the expression of genes. Initial applications of this approach are critically reviewed and potential applications of this approach with regard to immune response are presented.     

Effects of exercise on canine skeletal muscle proteolysis: an investigation of the ubiquitin-proteasome pathway and other metabolic markers

The effects of long-term athletic training are associated with excessive skeletal muscle turnover attributable to increased rates of myofibrillar protein synthesis and proteolysis, which are mechanisms poorly understood in the athletic dog. A physiologic field study using 44 English pointers and Labrador retrievers that had been purposely bred for bird hunting and retrieving was conducted to examine changes in the ubiquitin-proteasome (UP) pathway, which has been implicated in exercise-induced proteolysis. Muscle biopsy samples were collected from all dogs in September (preseason, pretraining) and February (peak season, peak activity). Western blot analysis was used to assess changes in expression of various components of the UP pathway in the biopsy samples. Citrate synthase and glycogen levels were also measured in a subset of these samples. Results across the population indicated pronounced up-regulation of ubiquitinated conjugates and the p31 regulatory capping subunit during the peak hunting period compared with the preseason period. In contrast, the catalytic core of the proteasome (beta-subunits) showed no apparent up-regulation in response to increased physical activity. Increased physical activity during the hunting season was associated with increased muscle glycogen levels and citrate synthase activity in these dogs. Overall, up-regulation of specific components of the UP pathway was an indication that it plays a role in the proteolytic process associated with skeletal muscle turnover during long-term athletic training, as previously believed.     

Expression of the μ Opioid Receptor and Effects of the Opioid Antagonist Naloxone on In Vitro Maturation of Oocytes Recovered from Anoestrous Bitches

The μ-opioid receptor (MOR) is expressed in bovine, human, equine and canine oocytes, and in seasonal breeders, it is expressed with higher intensity during the anoestrous phase. Supplementation of in vitro maturation (IVM) medium with opioid agents, agonists or antagonists, was shown to affect oocyte maturation in several species such as rat, bovine and equine. This study reports the effects of supplementing IVM medium with naloxone (Nx), an opioid antagonist, on nuclear and cytoplasmic maturation rate of oocytes recovered from anoestrous bitches. Cytoplasmic maturation was examined in terms of mitochondrial (mt) distribution. In order to confirm the receptor-mediated action of Nx, in oocytes of anoestrous bitches, MOR expression was analyzed by Western blot. Cumulus–oocyte complexes, recovered from the ovaries of bitches in anoestrous, were cultured in vitro and Nx was added at the concentrations of 1 × 10⁻⁶, 1 × 10⁻⁸ and 1 × 10⁻¹⁰  m . The rate of oocytes resuming meiosis after culture in presence of 1 × 10⁻⁶  m Nx (29%) was significantly higher than that of oocytes of control group (12%; p < 0.05). However, treatment with Nx did not affect mt distribution pattern. In denuded oocytes and in corresponding cumulus cells, a doublet of 65 and 50 kDa was observed. We conclude that, in oocytes of anoestrous bitches, MOR is expressed and Nx significantly improves nuclear maturation rate. Further studies should be performed to elucidate the expression of other opioid receptors, such as δ and κ, and possible interactive effects of their antagonists on canine oocyte maturation.     

IMAGING DIAGNOSIS—MAGNETIC RESONANCE IMAGING OF DIFFUSE LEPTOMENINGEAL OLIGODENDROGLIOMATOSIS IN A DOG WITH “DURAL TAIL SIGN”

A case of diffuse leptomeningeal oligodendrogliomatosis affecting the brain and spinal cord of a dog is presented. A 7.5‐year old, male neutered Staffordshire bull terrier presented for evaluation of a chronic history of tetraparesis and seizures, with a multifocal neuroanatomical localization was determined. Extra‐axial intradural lesions with an atypical presentation of a dural tail sign were seen on MRI. Histologically, the lesions were consistent with leptomeningeal oligodendrogliomatosis. To the authors’ knowledge, a dural tail sign has not previously been reported as an MRI characteristic of diffuse leptomeningeal oligodendrogliomatosis in dogs.