Physiological and genetic control of tuber formation

Summary Tuber formation is a plalstic and complex, but well-orchestrated sequences of morphological. physiological and biochemical events. The physiological control mechanisms of this sequence of events may involve many hormones, but certainly gibberellic acids play a dominant role: they affecft most steps and are influenced by inducing or non-inducing conditions in a manner consistent with effects of these conditions on tuber induction. The genetic control is also complex. Numerous cDNA fragments have been isolated which are specifically expressed during tuberization. They can be used in anti-sense orientation in transgenic plants to thest their possible role in tuberization. In addition these cDNA fragments are used as genetic marker loci in QTL mapping studies and serve as candidate genes to exlain phenotypic variation. Profiles of the importance of QTLs over time may be combined with expression profiles of candidate genes. Such novel approaches offer unique opportunities for synergism between physiology, molecular biology and genetics.     

Outcome and prognostic factors in infective endocarditis in dogs: 113 cases (2005‐2020)

BackgroundFactors associated with outcome in dogs diagnosed with infective endocarditis (IE) are not well characterized.ObjectivesEvaluate outcome and prognostic factors in dogs with IE.AnimalsOne hundred and thirteen dogs with IE.MethodsMedical records for dogs that fulfilled the modified Duke criteria between 2005 and 2020 were retrospectively reviewed. Signalment, preexisting conditions, clinicopathologic findings, treatment regimen, and outcomes were recorded. Univariate logistic regression was performed to identify categorical factors associated with mortality, and then multivariate analysis was performed.ResultsDogs were categorized as survivors (n = 47), non‐survivors (n = 57), or lost to follow‐up (n = 9). Survival to discharge and at 1 month was documented in 79 (70%) of 113 and 56 (54%) of 104 dogs, respectively, with median survival time (MST) of 72 days. Risk factors associated with mortality included development of congestive heart failure (odds ratio [OR], 11.8; 95% confidence interval [CI], 1.4‐97.8), thromboembolic events (OR, 5.7; 95% CI, 2.3‐14.4), and acute kidney injury (OR, 6.2; 95% CI, 2.0‐18.8). Administration of antithrombotic medications was associated with survival (OR, 0.35; 95% CI, 0.13‐0.97). Dogs that were not treated with antithrombotics had MST of 92 days, whereas dogs treated with antithrombotics did not reach MST during the study period. The heart valves involved and etiologic agent identified did not correlate with outcome.Conclusion and Clinical ImportanceDogs with IE that had thromboembolic events, acute kidney injury, or congestive heart failure had higher risk of mortality. Administration of antithrombotics was associated with prolonged survival time.     

Efficacy of the classical swine fever (CSF) marker vaccine Porcilis Pesti in pregnant sows

The efficacy of the classical swine fever (CSF) subunit marker vaccine Porcilis Pesti based on baculovirus expressed envelope glycoprotein E2 of CSF virus (CSFV) was evaluated in pregnant sows. Ten gilts were vaccinated with one dose of marker vaccine, followed by a second dose 4 weeks later. Four gilts remained unvaccinated and received a placebo at the same times. Thirty-three days after the second vaccination all animals were artificially inseminated. Neither local or systemic reactions nor an increase of body temperature were observed after vaccinations. All gilts showed a normal course of pregnancy. Thirty-five days after first vaccination all animals developed E2 specific neutralising antibodies with titres in the range of 5.0 and 7.5 log(2). No antibodies to CSFV-E(rns) were found in ELISA.On day 65 of gestation (126 days after the first immunisation) all sows were infected intranasally using 2ml (10(6.6) TCID(50)/ml) of the low virulent CSFV strain "Glentorf". After challenge in two of the unvaccinated control sows a slight transient increase of body temperature was observed, whereas leukopenia was demonstrated in all control animals. In addition all controls became viraemic. Vaccinations with the CSFV subunit vaccine protected the animals from clinical symptoms of CSF. In two sows a moderate decrease of leukocyte counts was detected on day 5 post infection. In contrast to the unvaccinated control sows in none of the vaccinated animals virus was isolated from the nasal swabs or the blood.Approximately 40 days after challenge all sows were killed and necropsy was done. The sows and their offspring were examined for the presence of CSFV in blood, bone marrow and different organs. No virus was found in any of the sows. In contrast, in all litters of the control sows CSFV was found in the blood as well as in the organ samples. Nine out of 10 litters of the vaccinated sows were protected from CSFV infection. Blood samples, lymphatic organs and bone marrow of these animals were all virologically negative. When sera were tested for CSFV-antibodies all sows had developed E(rns)-specific antibodies but no CSFV-specific antibodies were found in any of the progeny.It was concluded that vaccination with CSF subunit marker vaccine Porcilis((R)) Pesti protected 90% of the litters from viral infection when sows were challenged mid-gestation using the CSFV-strain "Glentorf".     

Examination of resistance to clubroot in accessions of Brassica oleracea using a glasshouse seedling test

A glasshouse test was elaborated for assessing large numbers of seedlings ofBrassica oleracea for resistance to clubroot, a disease caused by the fungusPlasmodiophora brassicae. The method offers good control of inoculum density per plant, and requires 6–7 weeks from sowing. The results from the glasshouse test correlated well with field test results. With this method, 71 accessions ofB. oleracea reported to carry resistance to clubroot, and one susceptible control cultivar were tested with a Dutch clubroot isolate. High levels of resistance were found in several accessions of cabbage, broccoli and curly kale. F₁-populations of resistant cabbage or curly kale × susceptible cabbage were fully susceptible, indicating recessive inheritance of resistance in all cases.     

Platelet‐Rich Fibrin Constructs Elute Higher Concentrations of Transforming Growth Factor‐β1 and Increase Tendon Cell Proliferation Over Time when Compared to Blood Clots: A Comparative In Vitro Analysis

Objective: To compare the concentration of a representative growth factor (transforming growth factor‐beta [TGF‐β]1) eluted from a platelet‐rich fibrin matrix (PRFMatrix), a platelet‐rich fibrin membrane (PRFMembrane), and a whole blood clot (BC) over time, and to compare the mitogenic effect of the eluents from each construct. Study Design: In vitro study. Sample Population: PRFMatrix, PRFMembrane, and BC (n=4/construct/time point). Methods: Each construct was placed in tissue culture wells containing media for 7 days. The media was collected and replenished on days 1, 3, 5, and 7 and the concentration of eluted TGF‐β1 was measured by enzyme‐linked immunosorbent assay. Canine tendon cells were subjected to additional aliquots of the conditioned media and the amount of cell proliferation compared. Results: The media from both PRFM (PRFMatrix and PRFMembrane) constructs contained significantly more (P≤.026) TGF‐β1 at days 1 and 3 and produced a significant increase (P≤.044) in cell proliferation at all time points compared with the BC. The PRFMembrane media contained significantly more (P≤.05) TGF‐β1 at days 1 and 3 and produced a significant increase (P≤.002) in cell proliferation at all time points compared with the PRFMatrix. Conclusions: Both PRFM constructs are comprised of a dense fibrin scaffold that contains increased concentrations of TGF‐β1 and are capable of increasing tendon cell proliferation over time when compared with a BC. Clinical Relevance: The sustained increase in growth factor availability in PRFM constructs may be beneficial in the healing of biologically compromised tissues.     

The timeline of metalloprotease events during oligofructose induced equine laminitis development

Reason for performing study: The role of matrix metalloproteases (MMPs) and the timeline of proteolysis during laminitis development are incompletely understood. Objectives: To determine the temporal progression of selected MMPs and protease regulators during laminitis development. Methods: Five clinically normal Standardbred horses received, via nasogastric intubation, an oligofructose (OF) bolus (10 g/kg bwt). Laminitis induction proceeded for 48 h followed by euthanasia. Lamellar biopsies were obtained prior to dosing and at intervals during the treatment period for analysis (12, 18, 24, 30 and 36 h and at 48 h following euthanasia). Tissue samples were analysed by real‐time PCR, zymography and western blotting. Results: Activation of proMMP‐2 occurs either simultaneously or at least 12 h following lamellar basement membrane (BM) damage, while no activation of proMMP‐9 is seen during OF laminitis induction. Aggrecanase gene expression increased initially at 12–18 h post OF dosing, similar to BM changes. Gene expression of TIMP‐2, a MMP regulator, decreases during laminitis development. Conclusions: The MMP‐2/MT1‐MMP complex may not play a major role in initiating lamellar BM damage. Aggrecanase and TIMP‐2 gene expression appear related to BM lamellar changes. Potential relevance: MMPs, historically thought to cause laminitis, do not appear to play an initiating role in the lamellar lesion. Other host derived proteases and degradation of alternative lamellar matrix components need to be considered.     

A tool for rapid assessment of erosion risk to support decision-making and policy development at the Ngenge watershed in Uganda

This study tests a rapid, user-friendly method for assessing changes in erosion risk, which yields information to aid policy development and decision-making for sustainable natural resources management. There is currently a lack of timely, up-to-date and current information to support policy development on sustainable natural resources management in Uganda. The study was carried out in the Ngenge watershed, a typical catchment in the Ugandan Highlands, characterised by deforestation in favour of subsistence agriculture without adequate soil and water conservation measures. The watershed is experiencing soil erosion, sedimentation and flooding problems which are threatening agricultural productivity and food security. Sustainable management of environmental resources is needed to ensure a livelihood for the rural population which is dependent on the land. Historical erosion risk was evaluated in three steps using multi-temporal satellite data. First, current erosion risk was assessed by combining slope and vegetation cover during periods of high intensity rainfall. The data used for the assessment was obtained from public (free) satellite images. Erosion risk was then linked to land use and finally to the change in vegetation cover over the years 1980-2000. The analysis of erosion risk using rainfall, slope and NDVI (Normalised Difference Vegetative Index) as a proxy for vegetation cover gives an indication of the current erosion risk in the area. The results of historical vegetation cover change analysis indicate an overall increase in areas under erosion risk in the study area from 1980 to 2000. This method of erosion risk mapping provides a quick and straightforward means for identifying priority areas for interventions for soil and water resource management. Considering that resources are limited, the interventions to be appropriate have to be focused mainly on areas affected by degradation.     

QTL mapping in diploid potato by using selfed progenies of the cross <Emphasis Type="Italic">S. tuberosum</Emphasis> × <Emphasis Type="Italic">S. chacoense</Emphasis>

Usually, mapping studies in potato are performed with segregating populations from crosses between highly heterozygous diploid or tetraploid parents. These studies are hampered by a high level of genetic background noise due to the numerous segregating alleles, with a maximum of eight per locus. In the present study, we aimed to increase the mapping efficiency by using progenies from diploid inbred populations in which at most two alleles segregate. Selfed progenies were generated from a cross between S. tuberosum (D2; a highly heterozygous diploid) and S. chacoense (DS; a homozygous diploid clone) containing the self-incompatibility overcoming S locus inhibitor (Sli-gene). The Sli-gene enables self-pollination and the generation of selfed progenies. One F2 population was used to map several quality traits, such as tuber shape, flesh and skin color. Quantitative trait loci were identified for almost all traits under investigation. The identified loci partially coincided with known mapped loci and partially identified new loci. Nine F3 populations were used to validate the QTLs and monitor the overall increase in the homozygosity level.