Mitochondrial DNA Copy Number in Spermatozoa of Fertile Stallions

Predicting male fertility on non‐invasive sperm traits is of big importance to human and animal reproduction strategies. Combining the wide range of parameters monitored by computer‐assisted sperm analysis (CASA) with some molecular traits (e.g. mtDNA content) may help to identify markers of the male fertility. The aim of this study was to characterize variation in the mtDNA copy number in equine sperm and to investigate whether mtDNA content is correlated with quality traits of stallion spermatozoa and the age of the male. Ejaculates collected from 53 fertile stallions were divided into four age groups (3–5, 6–10, 11–14 and >15 years) and were subjected to a complex investigation including conventional analysis, CASA, flow cytometry and mtDNA content (real‐time PCR). The mean (±SD) number of mtDNA copies equalled 14 ± 9 and varied from 3 to 64. Considering the great number of sperm parameters monitored in this study, only few of them were correlated with the mtDNA content: ejaculate volume (a positive correlation), the amplitude of lateral head displacement (ALH; a negative correlation) and the high mitochondrial activity index (a negative correlation). The stallion age was not correlated with the mtDNA copy number. This study provides the first set of data on mtDNA content in equine sperm and confirms phenomena previously described for humans and dog on associations between sperm mtDNA content and selected motility parameters monitored by the CASA. Basing our study on spermatozoa from fertile stallions could however limit the extent of detected associations.     

Exogenous paraoxonase‐1 during oocyte maturation improves bovine embryo development in vitro

Paraoxonase‐1 (PON1) is an enzyme found in serum and follicular fluid that protects cell membrane and circulating lipids against oxidative damage. The aims of this study were to measure the direct effects of recombinant PON1 (rPON1) on bovine oocyte maturation at the molecular level (gene expression) and to measure the carry‐over effects of PON1 on pre‐implantation embryo development in vitro. COCs were submitted to IVM with the addition of 0.0, 0.02, 0.04 and 0.08 mg ml^?1 of rPON1, corresponding to an average PON1 arylesterase enzyme activity of 2.2 ± 0.4, 15.5 ± 1.5, 30.2 ± 3.0 and 57.9 ± 5.0 U ml^?1, respectively. The results indicated that addition of rPON1 during IVM improved embryo development in a dose‐dependent manner as D7 embryo development was 22.2%, 29.4%, 32.2% and 37.0% for the treatment groups, respectively (p = 0.02). In conclusion, addition of PON1 enzyme during IVM exerted dose‐related positive effects on embryo development rates to blastocysts.     

A comparison of clinical,magnetic resonance imaging and pathological findings in dogs with gliomatosis cerebri,focusing on cases with minimal magnetic resonance imaging changes‡

The primary study objective was to determine whether clinical examination and magnetic resonance imaging (MRI) can underestimate canine gliomatosis cerebri (GC); we also investigated immunohistochemical features. Seven dogs with GC were studied; four recruited specifically because of minimal MRI changes. Neuroanatomic localization and the distribution of MRI, gross and sub‐gross lesions were compared with the actual histological distribution of neoplastic cells. In six cases, clinical examination predicted focal disease and MRI demonstrated a single lesion or appeared normal. Neoplastic cells infiltrated many regions deemed normal by clinical examination and MRI, and were Olig2‐positive and glial fibrillary acid protein‐negative. Four dogs had concurrent gliomas. GC is a differential diagnosis for dogs with focal neurological deficits and a normal MRI or a focal MRI lesion. Canine GC is probably mainly oligodendrocytic. Type II GC, a solid glioma accompanying diffuse central nervous system neoplastic infiltration, occurs in dogs as in people.     

IMAGING DIAGNOSIS—MULTIMODALITY FINDINGS IN AN ADULT DOG WITH PRIMARY SARCOMA OF THE PULMONARY ARTERY AND MYOCARDIAL METASTASES

Intravascular pulmonary artery sarcomas in combination with myocardial metastasis are rare in dogs. We describe the radiographic, echocardiographic, and electrocardiographic‐gated (ECG‐gated) computed tomographic angiography (CTA) findings in a dog with pulmonary artery sarcoma. All imaging studies demonstrated severe main pulmonary artery enlargement. Echocardiography and ECG‐gated CTA revealed a mass occluding the lumen of the right pulmonary artery. In addition, CTA revealed focal left ventricular myocardial contrast enhancement and parenchymal lung changes. Postmortem examination confirmed the presence of a large thrombus associated with arteriosclerosis and an intravascular sarcoma in the right pulmonary artery with metastases to the myocardium, lungs and brain.     

Effects of sub-minimum inhibitory concentration antibiotic levels and temperature on growth kinetics and outer membrane protein expression in Mannheimia haemolytica and Haemophilus somnus

The objective of this study was to determine the effects of sub-minimum inhibitory concentrations (sub-MICs) of 2 veterinary antibiotic preparations, chlortetracycline (CTC) and chlortetracycline-sulfamethazine (CTC + SMZ), on growth kinetics and outer membrane protein expression in Mannheimia haemolytica and Haemophilus somnus at normal and febrile body temperatures. Sub-minimum inhibitory concentrations of both antibiotics reduced the growth rates of M. haemolytica and H. somnus. Growth of both species was not inhibited when grown at 41 degrees C compared to 37 degrees C. There was no detectable consistent effect of antibiotic or temperature on outer membrane protein expression for either species. Our study indicates that sub-MIC levels of CTC and CTC + SMZ markedly impair growth of clinical M. haemolytica and H. somnus isolates, potentially allowing more effective host clearance during infection.     

Degradation and effect of hydrogen peroxide in small‐scale recirculation aquaculture system biofilters

From an environmental point of view, hydrogen peroxide (HP) has beneficial attributes compared with other disinfectants in terms of its ready degradation and neutral by‐products. The rapid degradation of HP can, however, cause difficulties with regard to safe and efficient water treatment when applied in different systems. In this study, we investigated the degradation kinetics of HP in biofilters from water recirculating aquaculture systems (RAS). The potential effect of HP on the nitrification process in the biofilters was also examined. Biofilter elements from two different pilot‐scale RAS were exposed to various HP treatments in batch experiments, and the HP concentration was found to follow an exponential decay. The biofilter ammonia and nitrite oxidation processes showed quick recuperation after exposure to a single dose of HP up to 30 mg L^?1. An average HP concentration of 10–13 mg L^?1 maintained over 3 h had a moderate inhibitory effect on the biofilter elements from one of the RAS with relatively high organic loading, while the nitrification was severely inhibited in the pilot‐scale biofilters from the other RAS with a relatively low organic loading. A pilot‐scale RAS, equipped with two biofilter units, both a moving‐bed (Biomedia) and a fixed‐bed (BIO‐BLOK^®) biofilter, was subjected to an average HP concentration of ～12 mg L^?1 for 3 h. The ammonium‐ and nitrite‐degrading efficiencies of both the Biomedia and the BIO‐BLOK^® filters were drastically reduced. The filters had not reverted to pre‐HP exposure efficiency after 24 h, suggesting a possible long‐term impact on the biofilters.     

A weight‐of‐evidence approach for defining thermal sensitivity in a federally endangered species

1. Managing for threatened and endangered species under changing environmental conditions is a challenge faced by resource managers worldwide. Lack of basic knowledge of the biology and habitat requirements of these species can contribute to this difficulty but is exacerbated by the limitations of working with rare species (i.e. few individuals) or unrefined and non‐lethal methods for evaluating stress.
2. A weight‐of‐evidence approach was used to evaluate the thermal biology of the federally endangered dwarf wedgemussel (Alasmidonta heterodon), using cumulative results from multiple experimental assessments, co‐occurring species, and their host fish to begin defining the thermal limits and optimal conditions for the species.
3. Results suggest that dwarf wedgemussel and its host fish are thermally sensitive species compared with other Atlantic‐slope mussels, with a lower critical thermal maximum (CTM) and the selection of reduced temperatures during choice experiments.
4. Physiological studies resulted in a lack of statistical significance, primarily owing to low power, which was a function of sample size – an unavoidable problem when studying rare species. Given these limitations, thermal choice and CTM may be more useful end points than physiological processes such as clearance and respiration rates when dealing with sample‐size limitations.
5. These results suggest that management strategies that avoid exposing dwarf wedgemussel and its thermally sensitive host fish to extreme temperatures could be important for species conservation.

     

Minimally invasive evaluation of the anaesthetic efficacy of MS‐222 for ornamental discus fish using skin mucus biomarkers

Skin mucus has been demonstrated to provide stress biomarkers for evaluating the physiological status, providing new convenient and non‐invasive methods to detect stress response in fish. Here, we investigated the anaesthetic efficacy of tricaine methanesulphonate (MS‐222; 75–115 mg/L) for discus Symphysodon aequifasciata (34.27 ± 4.46 g; 8.10 ± 0.59 cm) using skin mucus stress biomarkers. The induction time, recovery time and respiratory frequency were also determined. According to the criteria for anaesthesia and recovery, discus fish to reach stage A3 (deep anaesthesia) within 3 min and to reach stage R4 (full recovery of normal behaviour) within 5 min were observed at 95–105 mg/L MS‐222. Respiratory frequency increased first and then decreased during MS‐222 exposure and increased after recovery. At 10 min after deep anaesthesia, a lower mucus glucose was only observed at 115 mg/L MS‐222. No change in mucus cortisol and increased lactate were observed in all treatments. Increased mucus protein was observed at 75, 85 and 95 mg/L MS‐222. At 10 min after recovery, increased mucus glucose and decreased mucus protein were observed at 85, 95 and 115 mg/L MS‐222, but increased mucus cortisol only at 115 mg/L and lactate only at 75 and 105 mg/L MS‐222. At 24 hr after recovery, mucus glucose returned to the initial level only at 75, 95 and 105 mg/L MS‐222, while cortisol at 75 and 85 mg/L and protein and lactate at 75 mg/L respectively. Overall, the effective dose of MS‐222 for discus fish has been suggested to be 95–105 mg/L.     

Factors influencing the abundance of three common nearshore fishes in south‐west Lake Michigan

Variation in the distribution and abundance of nearshore fishes is critical to understand food web processes and fishery management issues in Lake Michigan. This study characterised patterns in abundance of three common nearshore species, yellow perch Perca flavescens (Mitchell), round goby Neogobius melanostomus (Pallas) and alewife Alosa pseudoharengus (Wilson), in relation to spatio‐temporal, abiotic and biotic factors using gillnet sampling conducted across 5 years at multiple locations representing different substrates. Significant variations were observed in alewife and round goby catches between locations. A negative relationship between round goby and age‐0 yellow perch catch was observed, indicating potential competition between the two species. This study demonstrates that variability in nearshore fish communities can be driven by factors including substrate and interspecific interactions. Given the prominent role these species play in Lake Michigan's food web and thus their importance to fishery production, a thorough understanding of these factors is warranted.