Brain derived neurotrophic factor and trk B mRNA expression in the brain of a brain stem-spinal cord regenerating model, the European eel, after spinal cord injury.

Evidence from mammalian studies suggests that brain derived neurotrophic factor (BDNF) and its receptor, trk B, are upregulated in neuronal cell bodies after injury. Although fish possess neurotrophins and display rapid functional and morphological recovery after central nervous system (CNS) injury, to date few studies have examined neurotrophin expression during CNS regeneration. In this study, RT-PCR was used to investigate the effect of complete spinal cord transection on the mRNA expression of BDNF and its receptor, trk B, in the eel brain at a range of timepoints after injury. The spatial expression pattern of BDNF mRNA in the brain was also assessed before and after injury using in situ hybridization. Marked changes in BDNF and trk B mRNA levels in the eel brain were not detected during the recovery period after cord transection. In addition, the spatial expression pattern of BDNF mRNA in the eel brain appeared unchanged after injury. Our results are in contrast with the increase reported in mammals but are in line with studies examining neurotrophin expression during CNS regeneration in other anamniotic vertebrates.

Brain-derived neurotrophic factor mRNA expression in the brain of the teleost fish, Anguilla anguilla, the European Eel.

The spatial expression pattern of Brain-Derived Neurotrophic Factor (BDNF) mRNA in the brain of the European eel (Anguilla anguilla) was determined using non-radioactive in situ hybridization, and mapped and compared to that of other vertebrates. Riboprobes were prepared based on a partial cDNA coding sequence for A. anguilla BDNF that was amplified using degenerate primers, cloned and sequenced. As in other animal groups, in the eel, BDNF mRNA expression was seen in the telencephalon, hypothalamus, tectum, many primary and secondary sensory centers, and cranial motor nuclei. However, in contrast to mammals, BDNF mRNA expression was observed in some brain stem nuclei, such as the reticular formation, that contain cell bodies of neurons that project down the spinal cord. We suggest that these differences might relate to the continual growth of teleost fish.

Humoral immune responses following experimental infection of goats with Mycoplasma capricolum subsp. capripneumoniae.

Goats housed in microbiologically secure facilities were experimentally endobronchially infected with Mycoplasma capricolum subsp. capripneumoniae (Mccp), causal agent of contagious caprine pleuropneumonia (CCPP). The animals were monitored over an 8-week period post-infection (p.i.). Elevated temperatures were observed 2-7 days p.i., reaching a maximum of 41.5 degrees C in one animal (1884). By 8 weeks p.i. the infection was successfully cleared, with no Mccp being recovered from the lungs, serum or nasal passages. Mccp was not isolated from serum throughout the experiment, either directly by culture or indirectly via polymerase chain reaction (PCR). Humoral immune responses against Mccp capsular polysaccharide (CPS) were generally poor when measured by ELISA. CPS antigen was present in the serum of all infected animals early in the infection (day 14 p.i.), although in one animal (1855) CPS antigen persisted throughout. This was the only animal to exhibit a serious cough (day 5-19 p.i.). Successful diagnosis of CCPP was achieved using two different types of latex agglutination test (CPS antibody and CPS antigen detection test), immunoblotting and a blocking ELISA, although the latter lacked sensitivity until later in the infection (35-40 days p.i.). Only a single animal (1855) was detected positive using the current complement fixation test (CFT). Strong immune responses to protein antigens were detected by IgG and IgM immunoblotting from the first time point at day 14 p.i. IgM immunodominant bands of 220, 85, 62 and 40kDa were observed in the 3 infected animals and from CFT-positive CCPP field sera. Band intensity gradually diminished throughout the experiment. IgG immunodominant bands of 108, 70, 62, 44, 40 and 23kDa were shared between experimentally-infected and field sera, with band intensity either remaining unchanged or increasing from day 14 p.i. These bands were not present using pre-infection sera. Of the diagnostic tests used, only the CPS antibody detection latex agglutination test and IgG immunoblotting gave positive diagnoses throughout the entire period post-infection (days 14-53 p.i.).