Uterine clearance mechanisms during the early postovulatory period in mares

Uterine response to inoculation with Streptococcus zooepidemicus organisms, 51Cr-labeled 15-microns microspheres, and charcoal was evaluated in 9 mares (4 resistant and 5 susceptible to endometritis) to determine mechanical and cellular clearance rates during the early postovulatory period. Mares were inoculated at estrus prior to ovulation during estrous cycles 1, 3, and 5. Uterine swab specimens for aerobic and anaerobic bacteriologic culture and serum for progesterone determination were obtained on postovulation day 3 during estrous cycle 1, on the day of ovulation during estrous cycle 3, and on postovulation day 5 during estrous cycle 5. Immediately thereafter, the uterus was irrigated with 50 ml of sterile physiologic saline solution containing tracer amounts of 125I-labeled human serum albumin. Streptococcus zooepidemicus was isolated from 10 of 15 (67%) uterine specimens collected from susceptible mares and incubated aerobically. Escherichia coli also was isolated from 2 of the 10 specimens incubated aerobically. Anaerobic bacteriologic culture of specimens from all mares yielded no growth. Chromium-labeled microspheres were recovered twice from 2 susceptible mares, on day 0 and day 5. Charcoal was retained in 5 specimens collected from 3 susceptible mares. Bacteriologic culture of specimens from resistant mares did not yield growth. On day 0, chromium-labeled microspheres and charcoal were recovered once from 1 resistant mare. Mares susceptible to endometritis accumulated more fluid within the uterine lumen after ovulation than did resistant mares (mean +/- SEM, 52.73 +/- 15.22 ml and 7.41 +/- 1.96 ml, respectively; P less than 0.01). From this study, it appeared that uterine cellular and bactericidal mechanisms are dysfunctional during the early postovulatory period. However, there appeared to be no disruption of the mechanisms responsible for mechanical clearance of materials inoculated in the uterus.     

In-hospital development of an aorto-cardiac fistula in a Warmblood gelding with chronic renal disease

A 20-year-old Warmblood gelding presented for evaluation and treatment of ventral oedema and azotaemia of unknown aetiology. On presentation, a diastolic heart murmur was appreciated and echocardiography revealed moderate aortic insufficiency due to chronic degenerative valve disease. The horse was hospitalised and failed to respond to oral and i.v. fluids and diuretics. Following discontinuation of all fluid and diuretic therapy, the horse became acutely agitated and developed monomorphic ventricular tachycardia. The ventricular tachycardia spontaneously converted to normal sinus rhythm, however the heart murmur changed in timing to a right basilar continuous murmur and bounding jugular pulses were noted. Repeat echocardiogram revealed an aorto-cardiac fistula with dissection into the basilar interventricular septum and left-sided chamber volume overload that was not previously present. Attempts at stabilisation were unsuccessful and euthanasia was elected. Post-mortem examination confirmed chronic renal disease of unknown aetiology in addition to an aorto-cardiac fistula originating from the right sinus of Valsalva with subsequent dissection into the basilar interventricular septum.     

Reference limits for biochemical and hematological analytes of dairy cows one week before and one week after parturition

Since dairy cows during the transition period have multiple endocrine and metabolic changes, it is necessary to determine the reference limits of laboratory analytes in normal transition cows. Reference limits for the weeks before and after calving were determined in dairy cows. Animals that had adverse clinical outcomes after calving and cows that were culled or had mastitis within the first 7 days after calving were excluded. All biochemical analytes (β-hydroxybutyrate, fatty acids, glucose, cholesterol, urea, calcium, and phosphorus) were statistically different between precalving and postcalving groups. The hematological analytes were not significantly different except for eosinophils. The data from precalving and postcalving cows were significantly different from reference limits in a university-associated laboratory derived from early- and mid-lactation cows. Different reference limits for precalving and postcalving dairy cows should be determined for biochemical analytes to ensure appropriate interpretation of results.     

African swine fever outbreak on a medium-sized farm in Uganda: biosecurity breaches and within-farm virus contamination

In Uganda, a low-income country in east Africa, African swine fever (ASF) is endemic with yearly outbreaks. In the prevailing smallholder subsistence farming systems, farm biosecurity is largely non-existent. Outbreaks of ASF, particularly in smallholder farms, often go unreported, creating significant epidemiological knowledge gaps. The continuous circulation of ASF in smallholder settings also creates biosecurity challenges for larger farms. In this study, an on-going outbreak of ASF in an endemic area was investigated on farm level, including analyses of on-farm environmental virus contamination. The study was carried out on a medium-sized pig farm with 35 adult pigs and 103 piglets or growers at the onset of the outbreak. Within 3 months, all pigs had died or were slaughtered. The study included interviews with farm representatives as well as biological and environmental sampling. ASF was confirmed by the presence of ASF virus (ASFV) genomic material in biological (blood, serum) and environmental (soil, water, feed, manure) samples by real-time PCR. The ASFV-positive biological samples confirmed the clinical assessment and were consistent with known virus characteristics. Most environmental samples were found to be positive. Assessment of farm biosecurity, interviews, and the results from the biological and environmental samples revealed that breaches and non-compliance with biosecurity protocols most likely led to the introduction and within-farm spread of the virus. The information derived from this study provides valuable insight regarding the implementation of biosecurity measures, particularly in endemic areas.     

Influence of ambient light and temperature on laser-induced chlorophyll fluorescence measurements

Chlorophyll fluorescence analysis is a powerful tool for the study of spatial and temporal heterogeneities of photosynthetic performance and has been successfully used at the laboratory scale. Field applications, however, are confronted with the challenges presented by fluctuating environmental factors, particularly varying light and temperature conditions.The influence of ambient light and temperature on the measurement signal of the laser-induced two-wavelength chlorophyll fluorescence remains both controversially and largely not well understood. Yet, a thorough understanding of this issue is essential for exploiting the large potential of this measurement method for precision agriculture as well as for precision phenotyping in plant breeding where the influence of ambient light and temperature is inevitably present. To fill this gap in our knowledge, we therefore investigated this area under both field and controlled laboratory conditions.Field measurements of laser-induced two-wavelength chlorophyll fluorescence under variable light conditions show a linear influence of direct sunlight on the ratio of F₆₉₀/F₇₃₀, whereas the ratio is unchanged under diffuse sunlight.We describe these measurement results in terms of a physical model of light–matter interaction in plant leaves. In particular, the results appear to derive from energetic saturation effects of the upper plant layers induced by sunlight, which result in larger mean depths of fluorescence emission induced by additional exciting light (i.e. laser light), in connection with the different scattering properties of the two different fluorescence light wavelengths (690 nm and 730 nm) on their way to the surface. The same model also provides an explanation for the temperature dependence of the fluorescence intensity ratio and is well suited to deal with the effects of both variable light and temperature conditions under field conditions.     

Abundance of ammonia oxidizing microbes and denitrifiers in different soil horizons of an agricultural soil in relation to the cultivated crops

The role of subsoils and their microbial communities for the nutrient supply for plants is to a large extent unknown, especially in comparison to well investigated topsoil layers. Therefore, in this study, the influence of three different plant species with different rooting systems and different N uptake strategies on ammonium and nitrate levels and microbial communities involved in ammonia oxidation and denitrification was investigated in different soil horizons. Overall, our results show a higher genetic potential for both processes in topsoils than in subsoils independent of the present plant. Although we found accumulation of N in top and subsoils in plots with legumes, we could not observe an impact of the higher nitrate content on the genetic potential of denitrification and ammonia oxidation. However, differences in the ratios of ammonia oxidizing archaea to bacteria and also between denitrifying bacteria harboring genes for copper- (nirK) or cytochrome- (nirS) dependent nitrite reductase in top and subsoil samples reveal different ecophysiologies of microbes involved in N turnover in top and subsoil habitats.     

Synthetic partial waves in ultracold atomic collisions

Interactions between particles can be strongly altered by their environment. We demonstrate a technique for modifying interactions between ultracold atoms by dressing the bare atomic states with light, creating an effective interaction of vastly increased range that scatters states of finite relative angular momentum at collision energies where only s-wave scattering would normally be expected. We collided two optically dressed neutral atomic Bose-Einstein condensates with equal, and opposite, momenta and observed that the usual s-wave distribution of scattered atoms was altered by the appearance of d- and g-wave contributions. This technique is expected to enable quantum simulation of exotic systems, including those predicted to support Majorana fermions.     

Phage Therapy is Effective in Protecting Honeybee Larvae from American Foulbrood Disease

American foulbrood disease has a major impact on honeybees (Apis melifera) worldwide. It is caused by a Gram-positive, spore-forming bacterium, Paenibacillus larvae. The disease can only affect larval honeybees, and the bacterial endospores are the infective unit of the disease. Antibiotics are not sufficient to combat the disease due to increasing resistance among P. larvae strains. Because of the durability and virulence of P. larvae endospores, infections spread rapidly, and beekeepers are often forced to burn beehives and equipment. To date, very little information is available on the use of bacteriophage therapy in rescuing and preventing American foulbrood disease, therefore the goal of this study was to test the efficacy of phage therapy against P. larvae infection. Out of 32 previously isolated P. larvae phages, three designated F, WA, and XIII were tested on artificially reared honeybee larvae infected with P. larvae strain NRRL B-3650 spores. The presence of P. larvae DNA in dead larvae was confirmed by 16S rRNA gene-specific polymerase chain reaction amplification. Survival rates for phage-treated larvae were approximately the same as for larvae never infected with spores (84%), i.e., the phages had no deleterious effect on the larvae. Additionally, prophylactic treatment of larvae with phages before spore infection was more effective than administering phages after infection, although survival in both cases was higher than spores alone (45%). Further testing to determine the optimal combination and concentration of phages, and testing in actual hive conditions are needed.     

Detecting the brook floater,a freshwater mussel species at risk,using environmental DNA

1. The use of environmental DNA (eDNA) is a promising approach for the detection of aquatic species, including species at risk. One freshwater mussel species of interest in Atlantic Canada, the brook floater (Alasmidonta varicosa), is listed as being of Special Concern under the Species at Risk Act in Canada and as Vulnerable on the International Union for Conservation of Nature Red List. Further scientific data regarding species distribution and critical habitat is needed for the protection and conservation of this species.
2. The aim of this study was to design, optimize, and apply a species-specific quantitative polymerase chain reaction assay for the detection of brook floater from eDNA samples, and to assess temporal variability in brook floater eDNA quantities.
3. Through an eDNA survey performed in New Brunswick rivers in 2017 and 2018, brook floater DNA was found at a total of 16 out of 56 sites sampled. The amount of brook floater DNA detected at all 16 sites was always below the theoretical limit of detection of the assay, and, as such, results were classified as either ‘inconclusive’ or ‘suspected’.
4. The co-detection of eastern pearlshell (Margaritifera margaritifera), a more abundant freshwater mussel species in Atlantic Canada, was successfully used as a natural positive control.
5. Temporal variability in the amount of eDNA found in the water was also assessed at a site with a known brook floater population and minimal variability in eDNA quantities was observed from May to September.
6. These results provide researchers and managers with a new tool for the detection of the brook floater in support of conservation and monitoring efforts.