Effect of Agroecological Conditions on Biologically Active Compounds and Metabolome in Carrot

Carrot serves as a source of health-beneficial phytochemicals for human diet whose content is affected by agroecological conditions. The effect of conventional, integrated and organic farming on ascorbic acid (AA) and α,β-carotene levels of new carrot cultivars Cortina F1 and Afalon F1 was investigated and their metabolomic profiles were measured by direct analysis in real time ion source coupled with a high-resolution mass spectrometer (DART-HRMS). Cortina and Afalon exhibited high levels of AA and total carotenes under all agroecological conditions tested that fluctuated in broad ranges of 215–539 and 173–456 mg AA.kg–1 dry biomass and 1069–2165 and 1683–2165 mg carotene.kg–1 dry biomass, respectively. The ratio of β- to α-carotene in both cultivars was about 1.3. The most important variable for the PCA and the partial least squares discriminant analysis (PLS-DA) models for ethyl acetate extracts measured in positive and negative ionization mode was 6-methoxymellein (6-MM). Total carotene content and 6-MM levels were higher in the organic carrot compared to the conventional one and were correlated with a higher level of spontaneous infection. Other important compounds identified were sitosterol, hexose and various organic acids including antioxidant ferulic and coumaric acids. The findings allow comparison of metabolomic profiles and the AA and carotene contents of both cultivars with those of other commercially used carrots.

Concentration phenomenon of the endemic equilibrium of a reaction-diffusion-advection SIS epidemic model with spontaneous infection

<p style='text-indent:20px;'>In this paper, we investigate the effect of spontaneous infection and advection for a susceptible-infected-susceptible epidemic reaction-diffusion-advection model in a heterogeneous environment. The existence of the endemic equilibrium is proved, and the asymptotic behaviors of the endemic equilibrium in three cases (large advection; small diffusion of the susceptible population; small diffusion of the infected population) are established. Our results suggest that the advection can cause the concentration of the susceptible and infected populations at the downstream, and the spontaneous infection can enhance the persistence of infectious disease in the entire habitat.</p>

Existence and asymptotic profiles of the steady state for a diffusive epidemic model with saturated incidence and spontaneous infection mechanism

<p style='text-indent:20px;'>In this paper, we are concerned with a reaction-diffusion SIS epidemic model with saturated incidence rate, linear source and spontaneous infection mechanism. We derive the uniform bounds of parabolic system and obtain the global asymptotic stability of the constant steady state in a homogeneous environment. Moreover, the existence of the positive steady state is established. We mainly analyze the effects of diffusion, saturation and spontaneous infection on the asymptotic profiles of the steady state. These results show that the linear source and spontaneous infection can enhance the persistence of an infectious disease. Our mathematical approach is based on topological degree theory, singular perturbation technique, the comparison principles for elliptic equations and various elliptic estimates.</p>

SCHISTOSOMIASIS OF ANIMALS IN ECOLOGICAL CONDITIONS OF THE ARAL SEA REGION

The problem of animal schistosomiasis is multifaceted. It intertwines veterinary, health, social and economic issues. The current state of the epizootology of schistosomiasis in the ecological conditions of the Aral Sea region is presented. Spontaneous infection of farm animals with mature Schistosoma turkestanica was 55.2% in cattle, sheep – 33.0%, horses – 21.5%, goats – 15.5% and camels – 10.2%. At individual farms of the Bozatau, Kungradsky, Muinaksky, Amudarya and other districts, cattle infection reached up to 100% with a high degree of infection intensity. We noted the cyclical nature of the epizootic of schistosomiasis in cattle in the Aral Sea region. The alternation of cyclicity is observed at specified intervals – from 15 to 20 years. The ups and downs in the infection intensity alternate with a certain accuracy, according to which epizootics of schistosomiasis can be predicted for several years in advance. Currently, science has developed the necessary prerequisites for a sharp decrease in the incidence of animals with schistosomiasis and the elimination of invasion in individual foci. This is achieved by a complex of therapeutic and preventive measures, as well as the use of progressive methods and technology of animal husbandry

REGULARITIES OF LARVAE SURVIVAL OF Oestrus ovis L. IN THE HOST BODY

Experiments with artificial invasion of sheep by larvae (Oestrus ovis L.) and experiments with surgical replacing of older gadfly larvae were conducted. Survival of larvae upon infection of 40 specimens higher (22.5%) than with infection of 20 and 80 specimens (10 and 11.2%), respectively. High percentage of death of larvae of II and III ages (63.7 and 58.4%) was found in the experimental replacing of larvae. It was shown that the natural resistance of larvae to adverse environmental factors increases with increasing age of the larvae. The hypothesis of a self-regulating level of sheep gadfly abundance in the parasitic system is discussed. The optimum abundance, which is characterized by the maximum survival and abundance of the parasite and is within 40 specimens based on the result of spontaneous infection, is considered. This level of infection allows maintaining a high reproductive potential of the parasite with a minimum of negative effects on the host.