Measurement of wind-induced motion of crop canopies from digital video images

We present a new measurement technique based on image correlation to capture the wind-induced motions of crop canopies. Tests were carried out on an alfalfa field submitted to natural wind. The motion is video-recorded from the side of the field and we take advantage of the natural periodicity of the crop to correct the distortion due to perspective. The computation of the canopy motions between successive images is based on Particle Image Velocimetry (PIV), and takes advantage of the natural small-scale heterogeneities of the canopy. It provides the two-dimensionnal spatio-temporal velocity field of the crop top surface with high spatial and temporal resolution. The Bi-Orthogonal Decomposition (BOD) of the velocity field then reveals large coherent propagating structures that scale with typical wavelength of wind fluctuation over canopies.     

Activation of central melanocortin pathways by fenfluramine

D-fenfluramine (d-FEN) was once widely prescribed and was among the most effective weight loss drugs, but was withdrawn from clinical use because of reports of cardiac complications in a subset of patients. Discerning the neurobiology underlying the anorexic action of d-FEN may facilitate the development of new drugs to prevent and treat obesity. Through a combination of functional neuroanatomy, feeding, and electrophysiology studies in rodents, we show that d-FEN-induced anorexia requires activation of central nervous system melanocortin pathways. These results provide a mechanistic explanation of d-FEN's anorexic actions and indicate that drugs targeting these downstream melanocortin pathways may prove to be effective and more selective anti-obesity treatments.     

Direct prediction of site-specific lime requirement of arable fields using the base neutralizing capacity and a multi-sensor platform for on-the-go soil mapping

Precision Agriculture - Liming agricultural fields is necessary for counteracting soil acidity and is one of the oldest operations in soil fertility management. However, the best management...     

Comparative evaluation of virulence and pathology of Streptococcus suis serotypes 2 and 9 in experimentally infected growers

Streptococcus (S.) suis is an invasive porcine pathogen causing meningitis, septicemia, arthritis and other diseases. Studies on pathogenesis as well as vaccine trials have focused on serotype 2 strains, which are worldwide the most prevalent among invasive isolates. However, in Europe serotype 9 strains also contribute substantially to S. suis-associated invasive diseases of piglets. The objective of this study was to determine the virulence of an MRP* SLY+ serotype 9 S. suis strain in comparison to an MRP+ EF+ SLY+ serotype 2 strain. Experimental intranasal and intravenous infections of 7-8 weeks old SPF piglets were investigated with regard to clinic and pathology. In contrast to the virulent serotype 2 strain, the serotype 9 strain did not cause disease with clinical manifestations after intranasal administration. However, histological screenings of these animals revealed pathological lesions, such as mild focal suppurative meningitis. Clinical manifestations related to meningitis, arthritis and serositis could be induced by intravenous application of this serotype 9 strain. Bacteriological culture and immunohistochemistry of the brain confirmed association with the S. suis challenge strains in all cases with clinical manifestations. Interestingly, expression of MRP within meningitis lesions was demonstrated for both pathotypes via immunohistochemistry. In conclusion, this study demonstrates that MRP* SLY+ serotype 9 strains are less virulent for growers than MRP+ EF+ SLY+ serotype 2 strains. Thus, intravenous application of this serotype 9 strain is required to evaluate heterologous protection in the course of vaccine development based on serotype 2 strains in the future.     

Multiplex qPCR assay for simultaneous quantification of CYP51-S524T and SdhC-H152R substitutions in European populations of Zymoseptoria tritici

Demethylation inhibitor (DMI) and succinate dehydrogenase inhibitor (SDHI) fungicides are currently relied upon for the control of septoria tritici blotch (STB) in European wheat fields. However, multiple mutations have occurred over time in the genes encoding the targeted proteins that have led to a practical loss of fungicide efficacies. Among the different amino acid substitutions in Zymoseptoria tritici associated with resistance to these fungicides, S524T in CYP51 (DMI target) and H152R in SdhC (SDHI target) are regarded as conferring the highest resistance factors to DMI and SDHI, respectively. To facilitate further studies on the monitoring and selection of these substitutions in Z. tritici populations, a multiplex allele-specific quantitative PCR (qPCR) assay allowing for estimation of both allele frequencies in bulk DNA matrices was developed. The assay was then used on complex DNA samples originating from a spore trap network set up in Belgium, Denmark, Sweden, and Ireland in 2017 and 2018, as well as on leaf samples with symptoms. The S524T allele was present in all field samples and its proportion was significantly higher in Ireland than in Belgium, whereas the proportion of H152R was only sporadically present in both countries. The frequency of S524T varied greatly in the airborne inoculum of all four countries; however, the H152R allele was never detected in the airborne inoculum. The method developed in this study can be readily adopted by other laboratories and used for multiple applications including resistance monitoring in field populations of Z. tritici.     

Pseudoperoxidase activity of myoglobin: kinetics and mechanism of the peroxidase cycle of myoglobin with H2O2 and 2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonate) as substrates

Using 2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) as substrate, it has been shown that the increased peroxidase activity for decreasing pH of myoglobin activated by hydrogen peroxide is due to a protonization of ferrylmyoglobin, MbFe(IV)=O, facilitating electron transfer from the substrate and corresponding to pK(a) approximately 5.2 at 25.0 degrees C and ionic strength 0.16, rather than due to specific acid catalysis. On the basis of stopped flow absorption spectroscopy with detection of the radical cation ABTS(.+), the second-order rate constant and activation parameters for the reaction between MbFe(IV)=O and ABTS were found to have the values k = 698 +/- 32 M(-1) s(-1), DeltaH# = 66 +/- 4 kJ mol(-1), and DeltaS# = 30 +/- 15 J mol(-1) K(-1) at 25.0 degrees C and physiological pH (7.4) and ionic strength (= 0.16 M NaCl). At a lower pH (5.8) corresponding to the conditions in meat, values were found as follows: k = 3.5 +/- 0.3 x 10(4) M(-1) s(-1), DeltaH# = 31 +/- 6 kJ mol(-1), and DeltaS# = -53 +/- 19 J mol(-1) K(-1), indicative of a shift from outersphere electron transfer to an innersphere mechanism. For steady state assay conditions, this shift is paralleled by a shift from saturation kinetics at pH 7.4 to first-order kinetics for H2O2 as substrate at pH 5.8. In contrast, the activation reaction between myoglobin and hydrogen peroxide was found at 25.0 degrees C to be slow and independent of pH with values of 171 +/- 7 and 196 +/- 19 M(-1) s(-1) found at physiological and meat pH, respectively, as determined by sequential stopped flow spectroscopy, from which a lower limit of k = 6 x 10(5) M(-1) s(-1) for the reaction between perferrylmyoglobin, .MbFe(IV)=O, and ABTS could be estimated. As compared to the traditional peroxidase assay, a better characterization of pseudoperoxidase activity of heme pigments and their denatured or proteolyzed forms is thus becoming possible, and specific kinetic effects on activation, substrate oxidation, or shift in rate determining steps may be detected.     

Conjunctival bacterial and fungal flora in healthy horses in the UK

Objectives To describe the bacterial and fungal flora of the normal conjunctiva of horses in the UK; to determine the effect of horse age, sex, geographic location, and housing on this flora; and to determine the most appropriate antimicrobial drug(s) for prophylactic treatment of corneal ulcers. Animal studied A total of 60 adult healthy horses were studied. Procedure Swabs of the conjunctiva were obtained from 60 horses housed in two locations within the UK. Specimens were cultured for aerobic bacteria and fungi, and sensitivity against six ophthalmic antimicrobials assessed. The effect of age, sex, location and housing on the frequency of microbial isolation was evaluated. Results Fifty‐four bacterial isolates, representing thirteen genera of bacteria were cultured from 31 (52%) horses. The most frequently isolated bacterial species was Acinetobacter sp (17/32 horses). The majority of isolates (28/54: 52%) were gram‐positive. Three genera of fungi (Mucor, Absidia and Aspergillus spp) were isolated from eight (13%) horses. There was no significant effect of geographic location, sex, age or housing on frequency of microbial isolation. Horses from which gram‐negative bacteria were isolated were significantly older than horses from which gram‐positive bacteria were isolated. High efficacy (greater than 90% of isolates sensitive in vitro) was displayed by chloramphenicol, gentamicin and tetracycline. Conclusions The microbial species isolated are comparable with studies performed in other countries, although the frequency of Acinetobacter isolation was higher which may reflect a geographic difference. The topical antimicrobials gentamicin and chloramphenicol are appropriate first line antimicrobials for empirical treatment of corneal ulcers in the UK.     

Culture of feline corneal epithelial cells and infection with feline herpesvirus-1 as an investigative tool

OBJECTIVE: To isolate and characterize pure cultures of feline corneal epithelial cells and to assess the extent and nature of feline herpesvirus (FHV)-1 infection in these cells. SAMPLE POPULATION: Healthy eyes from 23 recently euthanatized cats. PROCEDURE: Stroma and epithelium of the rostral portion of the cornea were surgically isolated, and epithelial cells were detached from the stroma by enzymatic incubation. Epithelial cells were cultured in hormone-supplemented media. Cells were passaged, and cytokeratin expression was assessed. Cells were then infected with FHV-1, and cytopathic effects were determined. RESULTS: Cell cultures were readily established from samples obtained from each eye and could be maintained through 6 passages. Cultured cells expressed cytokeratins 3 and 12 but not other cytokeratins. Infection with FHV-1 was rapid and caused widespread cytopathic effects. CONCLUSIONS AND CLINICAL RELEVANCE: Feline corneal cells cultured in vitro during multiple passages maintain consistent morphologic characteristics and intermediate filament expression. They are susceptible to infection with FHV-1 and may provide a useful in vitro model for investigation of ocular drugs.     

Modification of Standard Enzymatic Protocol to a Cost‐Efficient Format for Mixed‐Linkage (1→3,1→4)‐β‐d‐Glucan Measurement

The current enzymatic assay approach (AACC International Approved Method 32‐23) for the measurement of mixed‐linkage β‐glucan in small grains was modified to a cost‐efficient and high‐throughput format without compromising the accuracy of the results. Ten barley (Hordeum vulgare L.) genotypes used in the study represented a wide range of β‐glucan content levels. A reduced reaction volume is used in the new protocol to adapt to a 96‐well plate format. The volume of key components lichenase and β‐glucosidase were reduced to 25% of the volume required in the original protocol and the cost per sample was reduced to 22% of that in the original protocol. Labor cost was also decreased to 25% of the original protocol as a result of format changes. The accuracy of the measurement from the modified protocol was comparable to the current standard enzymatic procedure. β‐Glucan measurement accuracy of the modified and original protocols were also compared using 21 oat (Avena sativa L.) samples. The results indicated that the new protocol consistently produced accurate measurements in both barley and oat.     

Effect of Physical State of Nonpolar Lipids on Rheology and Microstructure of Gluten‐Starch and Wheat Flour Doughs

To clarify the effects of solid fat and liquid oil on dough in more detail in a simpler system, gluten‐starch doughs with different gluten contents were investigated. The results from rheological measurements indicate that dough with a higher starch content has less resistance to strain and dough with a lower starch content has a rubber‐like structure. The effects of the physical state of nonpolar lipids such as fat and oil on gluten‐starch doughs and wheat flour doughs were investigated using rheological measurements and scanning electron microscopy. Fat‐containing dough had more gas cells and a very smooth gluten gel surface with few holes, which may provide higher tolerance to strain. Moreover, the fat seemed to uniformly distribute the gluten gel between the starch granules in the dough, which reduced the friction between starch granules and led to a lower storage modulus. A mechanism governing the effect of fats on loaf volume is proposed based on the phenomena observed in the fat‐containing dough.