Bidirectional lncRNA Transfer between Cuscuta Parasites and Their Host Plant

Dodder species (Cuscuta spp.) are holoparasites that have extensive material exchange with their host plants through vascular connections. Recent studies on cross-species transfer have provided breakthrough insights, but little is known about the interaction mechanisms of the inter-plant mobile substances in parasitic systems. We sequenced the transcriptomes of dodder growing on soybean hosts to characterize the long non-coding RNA (lncRNA) transfer between the two species, and found that lncRNAs can move in high numbers (365 dodder lncRNAs and 14 soybean lncRNAs) in a bidirectional manner. Reverse transcription-polymerase chain reaction further confirmed that individual lncRNAs were trafficked in the dodder–soybean parasitic system. To reveal the potential functions of mobile transcripts, the Gene Ontology terms of mobile lncRNA target genes were predicted, and mobile dodder target genes were found to be mainly enriched in “metabolic process”, “catalytic activity”, “signaling”, and “response to stimulus” categories, whereas mobile soybean target genes were enriched in organelle-related categories, indicating that specific mobile lncRNAs may be important in regulating dodder parasitism. Our findings reveal that lncRNAs are transferred between dodder and its host soybean plants, which may act as critical regulators to coordinate the host–dodder interaction at the whole parasitic level.

Trophic Transfer without Biomagnification of Cadmium in a Soybean-Dodder Parasitic System

Cadmium (Cd) is among the most available and most toxic heavy metals taken up by plants from soil. Compared to the classic plant-animal food chains, the host-parasitic plant food chains have, thus far, been largely overlooked in the studies of Cd trophic transfer. To investigate the pattern of Cd transfer during the infection of parasitic plants on Cd-contaminated hosts, we conducted a controlled experiment that grew soybeans parasitized by Chinese dodders (Cuscuta chinensis) in soil with different levels of Cd treatment, and examined the concentration, accumulation, allocation and transfer coefficients of Cd within this parasitic system. Results showed that among all components, dodders accounted for more than 40% biomass of the whole system but had the lowest Cd concentration and accumulated the least amount of Cd. The transfer coefficient of Cd between soybean stems and dodders was much lower than 1, and was also significantly lower than that between soybean stems and soybean leaves. All these features were continuously strengthened with the increase of Cd treatment levels. The results suggested no evidence of Cd biomagnification in dodders parasitizing Cd-contaminated hosts, and implied that the Cd transfer from hosts to dodders may be a selective process.

Mutualists construct the ecological conditions that trigger the transition from parasitism

The evolution of mutualism between hosts and initially parasitic symbionts represents a major transition in evolution. Although vertical transmission of symbionts during host reproduction and partner control both favour the stability of mutualism, these mechanisms require specifically evolved features that may be absent during the transition. Therefore, the first steps of the transition from parasitism to mutualism are not fully understood. Spatial structure might be the key to this transition. We explore this hypothesis using a spatially explicit agent-based model. We demonstrate that, starting from a parasitic system with global dispersal, the coevolution between mutualistic effort and local dispersal of hosts and symbionts leads to a stable coexistence between parasites and mutualists. The local dispersal evolution mimics vertical transmission and triggers the formation of mutualistic clusters, counteracting the individual selection level of parasites that maintain global dispersal. However, the transition also requires competition between hosts in order to occur. Indeed, the transition occurs when mutualistic symbionts increase the density of hosts, which strengthens competition between hosts and disfavours parasitic host/symbiont pairs: mutualists create ecological conditions that allow their own spread. Therefore, the transition to mutualism may come from an eco-evolutionary feedback loop involving spatially structured population dynamics.

NATURAL AND SOCIAL FACTORS OF OPISTORCHOSIS CIRCULATION IN WEST KAZAKHSTAN REGION

The formation and course of epidemic and epizootic processes of opisthorchiasis is influenced by natural-ecological and socio-economic factors. Geographical position of the Ural River basin, the proximity of the Volga focus, species diversity and abundance of commercial species of cyprinids, ecological conditions in the Ural basin, in floodplain water bodies and in small rivers of West Kazakhstan region, connected with the Ural River, the dietary habits of people, intensive migration of population create optimal conditions for the functioning of parasitic system of opisthorchiasis and contribute to the spread of this invasion among the population of the Ural region.The risk of infection with opisthorchiasis at the natural and social levels remains high. The territory of West Kazakhstan region has the following natural and ecological conditions: it is confined to the Ural-Caspian lowland. Surface waters of West Kazakhstan region are represented by rivers, lakes and reservoirs. In the Ural River and its basin, there are many mollusks Bithynia leachi and fish species, among which there are potential carriers of opisthorchian metacercariae – bream, ide, dace, redfin, tench, wild carp, carp, white bream, roach, asp, prussian and crucian carp, chub, minnow, sabre fish, blue bream. In the region, the incidence of opisthorchiasis in people is annually recorded. A significant part of the infected population lives in settlements located along the banks of the Ural River and its floodplain reservoirs.

Interaction of concurrent infection pathogens in complex comorbidity (theoretical and practical issues)

In case of co-infections, the human body and the pathogen form a complex parasitic system. Also, the development of the infectious process is possible according to the following scenarios: infectious process activation caused by all pathogens; predominant activation of one of the infectious processes; absence of the infectious process activation; absence of combined infection interaction. Infectious pathogens affect the human body in different ways both at the site of permeation, launching a cascade of pathological processes, and at the site of the main localization. The formation of complex comorbidity depends on the non-specific immune defense, the biological properties of pathogens, the simultaneity or sequence of infection, the intervals between infection with various pathogens, etc. This article discusses the reasons for the predominance of one of the disease clinical manifestations in concurrent infections: synergism, antagonistic microorganisms, the chain of infection, the incubation period duration. The following variants of the co-infection course and their influence on complex comorbidity are considered: the dominance of one infection clinical manifestations; the same severity of symptoms of all infections, or the formation of a more severe clinical picture compared to single infections; the aggravating effect of one infection on another; the clinical picture overlap of one infection on another. KEYWORDS: mixed infection, concurrent infection, complex comorbidity, etiology, interaction of pathogens, parasitic system, infectious process, epidemic process. FOR CITATION: Shkarin V.V., Saperkin N.V. Interaction of concurrent infection pathogens in complex comorbidity (theoretical and practical issues). Russian Medical Inquiry. 2021;5(11):737–743 (in Russ.). DOI: 10.32364/2587-6821-2021-5-11-737-743.

Enzootic bovine leucosis

In an analytical discourse reviewed the available data on aspects of enzootic bovine leucosis that are little discussed in the domestic literature. The most important elements of pathobiosis as a transmission of infection and pathogenesis, its cellular and virological mechanisms, proviral load and the practical significance of its measurement, infection of the of newborns and the role of infected young animals in the spread of leucosis are interpreted from the current position of the parasitic system.

COMPOSITION OF LEUKOCYTES IN BLOOD OF GOLDFISH INFECTED BY LIGULA (DIGRAMMA) INTERRUPTA (CESTODA: PSEUDOPHYLLIDEA)

The tapeworm Ligula interrupta of the genus Ligula (Digramma) (Cestoda: Pseudophyllidea) is a specific parasite of freshwater cyprinid fish; its plerocyrcoids are localized in the body cavity causing heavy parasitic pathology. With parasitosis, an important role in the regulation of the pathological process is assigned to the participants of the organism’s protective reactions, among which a special pool of immunocompetent cells – leukocytes – is distinguished. In the literature, there are single data on hemo- and immunopoiesis goldfish with digrammosis. In our work, new data were obtained on the leukocyte composition of the blood of goldfish Carassius auratus (Linnaeus, 1758), infected with Ligula interrupta in conditions of the native range (Shilen Lake and Cheremukhovoe Lake, Lake Baikal basin). All fish specimens caught with seine nets, both infested and noninfested with L. interrupta, were identical by the size and age composition (age +3…+5, body length 145–237 and 150–180 mm, respectively, weight 100–184 and 120–174 g). Hematological studies were carried out according to the Sbornik [2]. To quantify the individual types of leukocytes, the leukocyte profile, expressed in absolute terms, was calculated. Three groups of cells were revealed in the blood of all goldfish species: blast forms, granulocytes (neutrophils, pseudobasophils) and agranulocytes (lymphocytes, monocytes). The decrease in the blood of infected fish of the total number of leukocytes and their various types at all stages of development, the violation of the proliferation and differentiation of lymphoid and granulocytic elements in the studied organs, the formation of vacuolated and atypical cells, the absence of circulating basophils and eosinophils were established. It has been shown that in this parasitic system, partner relations are reduced to the launch of L. interrupta mechanisms that regulate the host's protective immunological processes by the type of inhibition of the acute inflammatory response and the development of mild chronic inflammation.

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.

Features of the parasitic system formation in common carp in the aquaculture of the north-eastern and eastern regions of Ukraine

The research aimed to determine the peculiarities of the formation of the parasitic system in common carp in the aquaculture of the North-Eastern and Eastern regions of Ukraine. According to the results of the research, 27 species of parasites were found in common carp (12 — protozoa, 6 — monogeneans, 3 — trematodes, 2 — cestodes, 4 — parasitic crustaceans). Three species (11.1%) of registered parasites were invasive. 22 species (81.5%) of detected common carp’s parasites develop directly and 5 (18.5%) — with the participation of definitive and intermediate hosts. 26 species (96.3%) of common carp’s parasitic fauna were found in crucian carp and 21 species (77.8%) in other coarse fish species (roach, rudd, bleak, perch). It has been established that among the protozoa, pathogens from the genera Trichodina, Chilodonella, and Ichthyophthirius were of epizootic importance for young common carp; Eimeria carpelli, Ichthyobodo necator, Myxobolus ellipsoides, and Myxobolus dogieli had relevance. The level of prevalence in common carp fingerlings during outbreaks of chylodonelosis was 72%, two-year-olds — 65%, three-year-olds — 27%, during outbreaks of ichthyoftiriosis — 45%, 56%, and 24%, respectively. Prevalence of Trichodina acuta and Trichodina nigra in common carp fingerlings was, respectively, 52% and 38%, Ichthyobodo necator — 16%, Eimeria carpelli — 22%, Myxobolus ellipsoides, and Myxobolus dogieli — 17–18%. Among the pathogens of helminthic diseases in the aquaculture, monogenetic suckers (Dactylogyrus anchoratus, Dactylogyrus extensus, Dactylogyrus vastator, Gyrodactylus cyprini, and Gyrodactylus katharineri), as well as cestodes (Bothriocephalus acheilognathi and Khawia sinensis) were the most epizootic significance for common carp. Prevalence of parasites from the genus Dactylogyrus reached 68–87% in fingerlings, from the genus Gyrodactylus — 21–36%. The highest level of Bothriocephalus acheilognathi infection (82%) was registered in fingerlings. The maximum prevalence of Khawia sinensis (62%) was observed in two-year-olds. Outbreaks of diseases caused by crustaceans Lernaea cyprinacea and Argulus foliaceus with a high level of prevalence have been reported in fish from fingerlings to three-year-olds. The level of prevalence of Lernaea cyprinacea was 69%, Argulus foliaceus — 22%