Maximum Reproduction Research Articles

Floral traits and functional role of whorls in pollinator attraction of Magnolia grandiflora L.

Abstract Species within the primitive genus Magnolia may often produce specialized floral traits and behaviour to grab the attention of potential pollinators from their surroundings. These reproductive traits in plants undergo various selection pressures and frequently bring forth variations to adapt to the new habitat that may result in speciation. We have aimed to understand the floral traits, the functional role of floral parts, and the variable response of visitors in Magnolia grandiflora belonging to an ancient order Magnoliales. Our observations reveal that the floral traits of M. grandiflora resemble those of basal angiosperms, conforming to the primitive existence of the genus Magnolia. The inconsistency in floral form reflected that M. grandiflora has been experiencing various selection pressures from biotic and abiotic factors. Inconsistency in floral equations and diagrams reflect the structural variability in flowers, which can directly impact pollination and reproductive output. SEM images of pollen grains reveal that the pollen grains were monocolpate and boat-shaped in structure. GC-MS analysis showed that VOCs in stigmatic exudation of the flower were largely composed of terpene hydrocarbons such as Perthenine, β-Elemene, β-Caryophyllene, α-Humulene, Bicyclogermacrene, Germacrene A and D, etc. Beyond pollinators attraction, VOCs play a major role in repelling unwanted visitors and in improving the defensive mechanisms in Magnolia. Beetles, bees, and flies were found to be the active pollinators and the behaviour of bees indicates that bees were trying to replace the role of beetles in pollinating M. grandiflora. In summary, floral whorls were diversely functionalized to ensure maximum reproduction in M. grandiflora.

DEBBIES Dataset to study Life Histories across Ectotherms

Demographic models are used to explore how life history traits structure life history strategies across species. This study presents the DEBBIES dataset that contains estimates of eight life history traits (length at birth, puberty and maximum length, maximum reproduction rate, fraction energy allocated to respiration versus reproduction, von Bertalanffy growth rate, mortality rates) for 185 ectotherm species. The dataset can be used to parameterise dynamic energy budget integral projection models (DEB-IPMs) to calculate key demographic quantities like population growth rate and demographic resilience, but also link to conservation status or biogeographical characteristics. Our technical validation shows a satisfactory agreement between observed and predicted longevity, generation time, age at maturity across all species. Compared to existing datasets, DEBBIES accommodates (i) easy cross-taxonomical comparisons, (ii) many data-deficient species, and (iii) population forecasts to novel conditions because DEB-IPMs include a mechanistic description of the trade-off between growth and reproduction. This dataset has the potential for biologists to unlock general predictions on ectotherm population responses from only a few key life history traits.

Optimization of conditions for cultivation of pathogens of infectious rhinotracheitis and viral diarrhea

This article reflects the results of research on optimizing the conditions of cultivation of strain “ТК-A(VIEV)-В2” of infectious bovine rhinotracheitis (IBR) and strain “ВК-1” of bovine viral diarrhea (BVDV). It was found that the roller cultivation method is most easily applicable and provides the production of viral material with high infectious activity. A comparative analysis of the results of studying the sensitivity of continuous cell cultures to the pathogens of IBR and BVDV of cattle of the latter made it possible to select the MDBK cell line to obtain the maximum titer of viruses. The optimal dose for infecting cell culture with both pathogens was the content of viral particles from 0.2 to 0.5 TCD50/cm3 per cell. The maximum reproduction of viruses was observed using a culture concentration of cells from 110 to 120 thousand cells/cm3 and the duration of their cultivation for 2-3 days. The results obtained can be applied for the further development and creation of preventive and diagnostic tools for IBR and BVDV of cattle.

Life history of the two predacious mites species, Amblyseius swirskii, and Neoseiulus cucumeris (Acari: Phytoseiidae), as biological control agents of the date palm mite, Oligonychus afrasiaticus (Acari: Tetranychidae).

The date palm mite, Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae), is a serious pest of dates in the Middle East and North Africa, inflicting severe economic damage if not controlled early. As predaceous mites are known to be potential biocontrol agents against several pests, so predation capacity, life table, reproduction, and survival of Amblyseius swirskii Athias-Henriot and Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae), collected from date palm farms in Qassim Saudi Arabia, were studied under laboratory conditions (25 °C, 30 °C, 35 °C and 50 ± 5% RH) against all motile stages of O. afrasiaticus. For both predators, mean developmental time, oviposition period, and longevity were inversely related to temperature from 25 to 35 °C. Various parameters were studied for A. swirskii and N. cucumeris at 25 °C, 30 °C and 35 °C, i.e. the female developmental time, 9.37, 7.29, 5.56, and 10.67, 8.38, 6.45 d; oviposition period, 19.77, 16.18, 13.94 and 15.90, 13.84, 10.64 d; longevity, 29.39, 24.79, 20.64 and 25.42, 21.94, 17.39 d; fecundity, 31.91, 37.10, 42.16 and 21.75, 26.84, 30.56 eggs per female, respectively. The maximum daily predation rate for both the predators was recorded at 35 °C during the oviposition period. The total predation of A. swirskii and N. cucumeris female was 370.86, 387.54, 405.83, 232.14, 263.32, 248.85 preys at 25 °C, 30 °C and 35 °C respectively. The maximum reproduction rate of A. swirskii and N. cucumeris (3.02, 2.87 eggs/♀/day) was recorded at 35 °C while the minimum (2.00, 1.36 eggs/♀/day) was recorded at 25 °C. The life table parameters were estimated as net reproductive rate (Ro) 21.68, 25.94, 29.52 and 18.95, 20.25, 22.78; the mean generation time (T) 24.92, 21.82, 18.24 and 26.30, 23.60, 20.56 d; the intrinsic rate of increase (rm) 0.181, 0.232, 0.248 and 0.170, 0.185, 0.196; the finite rate of increase (λ) 1.365, 1.551, 1.706 and 1.126, 1.324, 1.428 for A. swirskii and N. cucumeris at 25 °C, 30 °C and 35 °C respectively. The results of this study suggested that the two phytoseiid species are promising biological control agents of O. afrasiaticus at a wide range of temperatures.

Analysis of a non-integer order mathematical model for double strains of dengue and COVID-19 co-circulation using an efficient finite-difference method

An efficient finite difference approach is adopted to analyze the solution of a novel fractional-order mathematical model to control the co-circulation of double strains of dengue and COVID-19. The model is primarily built on a non-integer Caputo fractional derivative. The famous fixed-point theorem developed by Banach is employed to ensure that the solution of the formulated model exists and is ultimately unique. The model is examined for stability around the infection-free equilibrium point analysis, and it was observed that it is stable (asymptotically) when the maximum reproduction number is strictly below unity. Furthermore, global stability analysis of the disease-present equilibrium is conducted via the direct Lyapunov method. The non-standard finite difference (NSFD) approach is adopted to solve the formulated model. Furthermore, numerical experiments on the model reveal that the trajectories of the infected compartments converge to the disease-present equilibrium when the basic reproduction number ({mathbb {R}}_0) is greater than one and disease-free equilibrium when the basic reproduction number is less than one respectively. This convergence is independent of the fractional orders and assumed initial conditions. The paper equally emphasized the outcome of altering the fractional orders, infection and recovery rates on the disease patterns. Similarly, we also remarked the importance of some key control measures to curtail the co-spread of double strains of dengue and COVID-19.

Theoretical and Methodological Approaches to the Analysis of the Spatial Distribution of Endemic Diseases of Geochemical Nature

—Throughout millions of years of geological history (in the Phanerozoic), the coevolution of all living organisms took place in a fierce competition for resources and opportunities for the maximum reproduction. Due to the geochemical heterogeneity of the primary (pre-Quaternary) biosphere, this resulted in a self-regulating system of ecological niches, within which all local biocenoses and their animal and plant species were maximally adapted to the parameters of the habitat. However, with the emergence of reason, the situation changed fundamentally. Human beings became the dominant species and began the conscious development of new territories, including geochemically unfavorable ones, which led to the formation of zones of stable endemic diseases. Based on this premise, for all existing species, there should be areas with physiologically optimal habitat conditions, i.e., those under which the species has evolved to its present state. It follows that, by being able to record the geochemical parameters of the undisturbed biosphere, it is possible to obtain characteristics that are ecologically ideal for local animal and plant species. In theoretical terms, this allowed us to put forward the hypothesis that by fixing the difference between observed and ideal geochemical conditions, it is possible to build maps of risk of diseases of geochemical nature, including in areas subjected to anthropogenic pollution. The paper outlines the methodology and gives examples of construction of such maps. The obtained results can have an important practical value in organizing the system of sanitary–epidemiological service, in solving the problems of liquidation of the consequences of anthropogenic pollution, and in carrying out preventive measures to minimize the risk of diseases of geochemical nature.

Theoretical and Methodological Approaches to the Analysis of Peculiarities of Spatial Distribution of Endemic Diseases of a Geochemical Nature

Over millions of years of geological history (Phanerozoic), the co-evolution of all living organisms took place in condtions of fierce competition for resources and opportunities for maximum reproduction, which, given the geochemical heterogeneity of the primary (pre-Quaternary) biosphere, resulted in a self-regulating ecological niche system, within which all local biocenoses and their animal and plant species were adapted to the parameters of the habitat to the maximum extent. However, with the development of the brain and the emergence of reason, the situation changed radically. Humans became the dominant species and began to develop new territories, including geochemically unfavourable ones, which caused the formation of zones of persistent endemic diseases. Based on this premise, for all existing species, there must be territories with physiologically optimal habitat conditions, i.e. those in which the species was formed in its present form. This implies that by being able to determine the geochemical parameters of the undisturbed biosphere, it is possible to obtain characteristics corresponding to the ecologically ideal ones for local animal and plant species. In theoretical terms it has allowed to put forward the hypothesis that by fixing the difference between the observed and ideal geochemical conditions it is possible to build maps of risk of diseases of geochemical nature, including those caused by technogenic pollution. The article presents a methodology and examples of such mapping. The results obtained may have an important practical value in improving the system of sanitary and epidemiological services, in solving problems of carrying out preventive measures to minimize endemic morbidity eliminating endemic diseases.

Epidemiological Characteristics of COVID-19 in Chungju City from 2021 July to 2021 December

Objectives: This study aimed to investigate the epidemiological characteristics of COVID-19 in Chungju City from July to December 2021.Methods: The authors processed and analyzed the epidemiological analysis report written by researcher. The estimated reproduction rate was analyzed using web-based software that calculates time-varying reproduction numbers. The results were analyzed through univariate multiple regression analysis, with a maximum significance level set at 0.05.Results: During the study period, a total of 1,188 patients were identified, with 7.9% of them progressing to a severe status. The maximum reproduction rate recorded was 3.48. Factors associated with the transition to a severe status included the presence of symptoms at the time of diagnosis, lack of vaccination, and belonging to the age group over 40.Conclusion: Based on the findings of this study, it can be strongly supported that the measures implemented in Chungju City, such as social distancing, vaccination, and preemptive diagnostic tests, were appropriate. Furthermore, it demonstrates that Chungju City effectively managed the impact of COVID-19. Korean Medicine Doctors made significant contributions to the epidemiological investigations of COVID-19. To comprehensively manage infectious diseases, it is crucial to provide administrative and legal support and encourage active research to expand the role of Korean Medicine Doctors in this area.

FORMATION OF THE ABILITIES AND SKILLS OF WORKING WITH SCIENTIFIC TEXTS IN THE LANGUAGE TRAINING PROCESS FOR HIGHER EDUCATION STUDENTS IN THE CLASSES OF THE COURSE «UKRAINIAN LANGUAGE (BY PROFESSIONAL DIRECTION)»

The formation of abilities and skills of work with scientific texts in the process of language training for higher education students is an actual problem of modern pedagogy, as bachelor’s mastering of technologies to work with these texts allows to develop the scientific competence of the future specialist. At the classes on the educational discipline «Ukrainian language by professional direction» the main attention is paid to the formation of abilities and skills of higher education graduates to interact freely in the sphere of professional communication, and to create primary and secondary scientific texts on a specialty profile. The purpose of this article is to describe the technology of drawing up the secondary scientific texts (plan, theses, abstract) to form the abilities and skills of higher education graduates in the analytical-synthetic processing of original text. Research methods applied: analysis and synthesis of scientific literature (to clarify the key concepts of the study), systematization (in order to identify existing scientific approaches to solving the problem), theoretical generalization (to formulate the final provisions and conclusions). The article considers the signs of scientific text (integrity; connectivity; consistency; information-format, logical, estimated saturation), which is important in the process of compression of the primary text, i.e. reduction of the volume of written without loss for its content. The compression of scientific text provides maximum reproduction of the content with a smaller number of language means. The article analyzes the peculiarities of the compression stages of secondary scientific texts. The appointment of different types of plan (expanded, interrogative, nominal and quote) is outlined. The types of theses (chosen by the quote author from the first place and handed over by his own words the most important of his provisions) were considered, the difference between the plan and theses was confirmed. Specific features of different types of abstract (informative, indicative, overview) are described. The text creation of these genres in scientific style according to the technology mentioned in the article helps to form the necessary abilities and skills of scientific and research activity in the higher education graduates.

<i>In vitro</i> Study of Biological Properties of SARS-CoV-2 Coronavirus Strains Related to Various Genetic Variants

The aim of the research was to study reproduction features of SARS-CoV-2 coronavirus strains of various genetic lines on Vero and Vero E6 cell culture.Materials and methods. The SARS-CoV-2 virus strains related to the variants of concern (VOC) circulating in the territory of the Russian Federation were used in the research. The strains of the SARS-CoV-2 virus were deposited in the State Collection of Pathogens of Viral Infections and Rickettsioses at the FBIS SSC VB “Vector” of the Rospotrebnadzor. The experiments were carried out on Vero and Vero E6 cell cultures. The dynamics of infectious virus accumulation was determined by titration of culture fluid samples 24, 48, 72, 96 hours after infection (MOI – from 1 to 0,00001 CPE50/cell). Plaque formation was studied on Vero E6 cell culture under 0.2 % agar coating. Image analysis and plaque size calculation were performed using GIMP (GNU Image Manipulation Program).Results and discussion. The study describes the dynamics of accumulation of infectious virus in the culture fluid depending upon multiplicity of infection for the strains of SARS-CoV-2 virus belonging to different genetic lines. Differences in the morphology of plaques on the monolayer of Vero E6 cell culture under agar coating are shown. SARS-CoV-2 virus strains related to Alfa and Delta VOC demonstrate maximum reproduction rate among the studied strains (infectious titer is higher than 7 lg TCID50/100µl). Omicron VOC forms small plaques under agar coating and at a low multiplicity of infection has a low reproduction rate. Thus, SARS-CoV-2 virus strains belonging to different genetic lines have significant differences in the rate of reproduction on Vero and Vero E6 cell culture.

Maximal reproduction number estimation and identification of transmission rate from the first inflection point of new infectious cases waves: COVID-19 outbreak example

The dynamics of COVID-19 pandemic varies across countries and it is important for​ researchers to study different kind of phenomena observed at different stages of the waves during the epidemic period. Our interest in this paper is not to model what happened during the endemic state but during the epidemic state. We proposed a continuous formulation of a unique maximum reproduction number estimate with an assumption that the epidemic curve is in form of the Gaussian curve and then compare the model with the discrete form and the observed basic reproduction number during the contagiousness period considered. Furthermore, we estimated the transmission rate from identification of the first inflection point of a wave of the curve of daily new infectious cases using the Bernoulli S–I (Susceptible–Infected) equation. We applied this new method to the real data from Cameroon COVID-19 outbreak both at national and regional levels. High correlation was observed between the socio-economic parameters and epidemiology parameters at regional level in Cameroon. Also, the method was applied to the second wave COVID-19 outbreak for the world data which is a period the phenomena we are considering were observed. Lastly, it was observed that the models presented results correspond with the epidemic dynamics in Cameroon and World data. We recommend that it is important to study what happened during the growth inflection point as some countries data did not climax.

Method for the estimation of antibacterial activity of the polyfunctional protein from transferrin family in the experimental model of the kinetics of Staphylococcus aureus development

Introduction. Lactoferrin is a cationic monomeric glycoprotein produced by acinar cells and glands, present in different places of the mucous membrane in different concentrations. In connection with the development of various variants of hygienic and medicinal products for the treatment of inflammatory diseases of the oral cavity based on lactoferrin, there was a need for an objective assessment of its antibacterial and antibiofilms properties, followed by an analysis of the preservation of activity in various variants of the isolation of this protein from the substrate and storage.Aim - to improve the effectiveness of evaluating the antibacterial activity of lactoferrin and the duration of its preservation in various biological substrates containing the active substance and individual experimental batches of the manufactured drug using automatic cultivation.Materials and methods. As part of the experiment, a microbiological diagnostic technique employing a system for the automatic cultivation of microbial populations was used. A pre-prepared bacterial suspension was inoculated into the nutrient broth and the studied lactoferrin samples were added, followed by cultivation and analysis of the possible antibacterial effects of transferrin protein. To determine the sensitivity of the isolated strains, we used our own modification of the serial dilution method developed at the Department of microbiology, virology, immunology of the A.I. Yevdokimov Moscow State University of Medicine and Dentistry. The experiment was based on the programmed automatic cultivation using the RTS-1 bioreactor. The interpretation of the results was carried out by changing the optical density at a wavelength of λ = 850 nm. The study of the growth dynamics of microorganisms was carried out in several repetitions, which was reflected in the graphs of the development of bacterial populations. The assessment of the growth control of the corresponding bacterial species was reflected in the change in the optical density values, on the basis of which the curve was built. Results and discussion. According to the results of an experimental study of the growth curves of bacterial populations, statistically significant differences in the number of viable cells in different phases of the growth curves were noted, when using different lactoferrin samples. Higher activity of human recombinant lactoferrin samples was established. An analysis of growth dynamics revealed differences in the onset of the maximum reproduction and its inhibition under the influence of various aggravating factors during cultivation. The bacteriostatic effect of lactoferrin is realized through the binding of iron ions, depriving the bacteria of this microelement, causing inhibition of their development. Along with this, lactoferrin is active against certain virulence factors of microorganisms, splitting them like serine proteases, and thus prevents their penetration into human cells.Conclusion. The method used for automatic cultivation of microorganisms in the bioreactor used allows one to obtain reproducible results, is available for wide use, and can be recommended for obtaining objective, comparable, reliable information about the antimicrobial properties of various samples of the bactericidal protein lactoferrin produced by the domestic pharmaceutical industry. The studied substrate containing recombinant human lactoferrin of Russian production is characterized by high antibacterial activity that persists for 3 years as minimum.

Some clonal micropropagation features ofLonicera caeruleaL. cultivarsin vitro

Lonicera caeruleaL. is one of the early temperate berry crops. Honeysuckle is a deciduous shrub up to 2.5 m high with edible blue fruits rich in vitamins and polyphenols. The work is devoted to the improvement ofin vitropropagation method of someLonicera caeruleacultivars. The differences in regeneration and formation of axillary shoots were revealed depending on the mineral medium composition. The optimal mineral composition of the nutrient medium for clonal micropropagation of the studied genotypes was determined. Cultivation on of Quoirin and Lepoivre medium contributed to the maximum reproduction coefficient (14.3) and height of microshoots (5.1 cm). The optimal concentration of auxin at the rooting stage has been established. The highest percentage of rooted microshoots (91%) was noted on a nutrient medium with 0.3 mg/l indoleacetic acid.

Parametric assessment of lactoferrin activity in experiment and clinical application

The possibilities of using lactoferrin preparations for the destruction of microbial biofilms as the leading factors in the development of oral diseases are considered.
 Materials and methods. As part of the experiment, a microbiological diagnostic technique was used using a system for the automatic cultivation of microbial populations. A pre-prepared bacterial suspension was inoculated into the nutrient broth and the studied lactoferrin samples were added, followed by cultivation and analysis of the possible antibacterial effects of transferrin protein. The infrastructure of the Unique scientific installation “Transgenbank” was used in the work. The assessment of the growth control of the corresponding type of bacteria was reflected in the change in the optical density parameters, on the basis of which the curve was constructed.
 Results. According to the results of an experimental study of the growth curves of bacterial populations, statistically significant differences in the number of viable cells in different phases of the growth curves were noted. The analysis of growth dynamics revealed differences in the onset of maximum reproduction and its inhibition under the influence of various aggravating factors during cultivation. The bacteriostatic effect of lactoferrin is realized by binding iron ions, depriving bacteria of this trace element, causing inhibition of their development.
 Conclusion. With local application of lactoferrin-containing drug in the complex periodontal treatment of patients, normalization of the clinical picture of periodontitis was established, a statistically significant decrease in the indices of OHI-S, PHP, PMA, PBI and SBI indices in the dynamics of clinical observation, which remained optimal for 1 year. The used bioreactor allows to obtain reproducible results, is available for wide use and can be recommended for obtaining objective, comparable, reliable information about the antimicrobial properties of various samples of the bactericidal protein lactoferrin produced by the domestic pharmaceutical industry.

Selection of suitable predatory mites against, Panonychus citri (McGregor) (Acari: Tetranychidae) using relative control potential metrics and functional response

BackgroundSelection of suitable predators for the control of the spider mite, Panonychus citri is always a challenge due to the lack of their reliable predicted efficacy. In this laboratory study, biological control potential of Neoseiulus californicus, N. cucumeris and Scapulaseius newsami, against P. citri using the “Relative Control Potential” (RCP) metric to compare their efficacies was evaluated. The functional response type was determined at different prey densities (after 24 h).ResultsThe type II functional responses were observed from all the tested predators feeding on 3 different life stages of P. citri, except N. cucumeris, which was fed only on eggs. All predatory mites preferred eggs of P. citri with a higher attack rate (1.397) in N. cucumeris, followed by N. californicus (1.238) and S. newsami (0.975). Handling time was also lower in N. cucumeris than other mites, with a trend as: for N. cucumeris, eggs > adults > immature stages; for N. californicus, immature stages > eggs > adults, while for S. newsami, eggs > immature stages > adults. The integration of greenhouse abundance and fecundity (%) data resulted in a higher RCP for N. cucumeris than other predators.ConclusionNeoseiulus cucumeris was selected as the most suitable predatory mite for the control of P. citri with a higher RCP and potential to maximum reproduction. S. newsami, which was used for the first time, gave almost similar results compared to N. californicus but with lower efficacy.

Evaluation of the combined effect of elevated temperature and cadmium toxicity on Daphnia magna using a simplified DEBtox model

Thermal discharge and heatwaves under climate change may increase water temperature. In this study, the individual and combined effect of elevated temperature and cadmium (Cd) toxicity on somatic growth and reproduction of Daphnia magna was evaluated using a simplified dynamic energy budget model (DEBtox). The model predicted that the maximum body length (Lm) would be shorter (3.705 mm) at an elevated temperature of 25 °C than at 20 °C (3.974 mm), whereas the maximum reproduction rate (R˙m) would be higher at 25 °C (5.735) than at 20 °C (5.591). The somatic growth and reproduction of D. magna were significantly (p < 0.05) reduced with increasing Cd concentrations, and the reduction was greater at 25 than at 20 °C. Potentiation of Cd toxicity by elevated temperature was correctly simulated by assuming four toxicological modes of action influencing assimilation, somatic maintenance and growth, and reproduction. Overall, the population growth rate of D. magna was expected to decrease linearly with increasing Cd concentrations, and the decrease was expected to be higher at 25 than at 20 °C. These findings suggest a significant ecological risk of toxic metals at elevated temperature, with a mechanistic interpretation of the potentiation effect using a DEBtox modeling approach.

The analysis of planktonic algae structure in the Volga and Kama rivers (Republic of Tatarstan)

The paper presents the results of a comparative analysis of planktonic algae structure in the Volga and Kama rivers at the confluence of the Kuibyshev reservoir. The author has also assessed the trophic state of the studied river sections in 2012. The hydrochemical regime of the Kuibyshev reservoir is heterogeneous and is determined by the chemical composition of the Volga and Kama waters, which differ in the ratio of ions and mineralization. The ionic composition of the Kama waters is often dominated by sulfates. The salinity depending on the season and water content of the year ranges from 168 to 674 mg/l. The Volga waters contain calcium bicarbonate and have a lower mineralization (120130 mg/l). The variability of the incoming water, the amount of runoff, the degree of volume drawdown within water bodies and groundwater inflows primarily affect the conditions for planktonic algae existence. In the phytoplankton of the Volga and Kama rivers (areas before their confluence in the Kuibyshev Reservoir), 123 taxa of algae were identified during the 2012 growing season. The waters of the Volga River have a higher species diversity (107 species). The phytoplankton of the Kama River is less diverse (76 species). In the seasonal dynamics of phytoplankton in the studied river sections, two peaks of abundance and biomass are observed by the middle of summer and at the end of it, when the maximum values of abundance and biomass are reached. The waters of the investigated sections of the Volga River is characterized by a complex of phytoplankton of blue-green, diatoms and green algae, while the Kama River is dominated by diatom phytoplankton. In summer and autumn the blooming of water in both rivers is due to the massive development of blue-green algae of the genera Microcystis, Aphanizomenon, Anabaena, Oscillatoria. The waters of the Volga and Kama rivers in 2012 during the study period corresponded to the mesasaprobic type and moderately polluted zone; the waters of the Kama River had higher saprobity indices. The trophic status of the rivers under consideration in the study area was mostly related to the eutrophic type; during the periods of maximum reproduction of blue-green algae to the hypereutrophic type.

Effect of Citrullus amarus accessions on the population dynamics of Meloidogyne incognita and M. javanica and watermelon yield

The aims of this study were to determine i) the effect of grafted watermelon cv. Sugar Baby onto C. amarus accessions BGV0005164 and BGV0005167 on M. incognita and M. javanica population growth estimated by means of the values of maximum reproduction rate, maximum nematode density and equilibrium density in pot experiments; ii) the effect of increasing nematode densities on plant productivity in pot experiments; and iii) the effect of repeated cultivation of watermelon cv. Sugar Baby grafted onto both C. amarus accessions and onto C. lanatus ‘Robusta’ during two seasons in a plastic greenhouse on M. incognita reproduction, disease severity, crop yield and selection for nematode virulence. In pot experiments, the values of maximum reproduction rate, maximum nematode density and equilibrium density of M. incognita were 37 %, 72 % and 68 % lower in watermelon grafted onto BGV0005164 than in ungrafted, and 28 %, 76 % and 77 % lower when grafted onto BGV0005167. Regarding M. javanica, the values of maximum reproduction rate, maximum nematode density and equilibrium density in watermelon grafted onto BGV0005164 were 88 %, 65 % and 14 % lower than in ungrafted, and 80 %, 76 % and 33 % lower when grafted onto BGV0005167. Dry shoot weight of ungrafted and grafted watermelon inoculated with a range of nematode densities between 0 and 1200 s-stage juveniles per 100 cm3 of soil was not affected, irrespective of the nematode isolate. In the plastic greenhouse experiment, M. incognita reproduced less in grafted than in ungrafted watermelon. Disease severity was higher in ungrafted than in grafted watermelon. The level of resistance of both C. amarus accessions was not affected after two-year cultivation, but it decreased from moderately resistant in 2017 to slightly resistant in rootstock ‘Robusta’. Watermelon grafted yielded between 2.9 and 5.6 kg more per plant than the ungrafted in 2017, and between 2.0 and 2.7 kg more per plant in 2018. In conclusion, C. amarus accessions BGV0005164 and BGV0005167 performed as poorer hosts to M. incognita and M. javanica. Watermelon grafted onto these C. amarus accessions improved fruit yield when they were cultivated in nematode infested soils without affecting its level of resistance to M. incognita after two consecutive crops.

Environmental variation mediates the evolution of anticipatory parental effects.

Theory maintains that when future environment is predictable, parents should adjust the phenotype of their offspring to match the anticipated environment. The plausibility of positive anticipatory parental effects is hotly debated and the experimental evidence for the evolution of such effects is currently lacking. We experimentally investigated the evolution of anticipatory maternal effects in a range of environments that differ drastically in how predictable they are. Populations of the nematode Caenorhabditis remanei, adapted to 20°C, were exposed to a novel temperature (25°C) for 30 generations with either positive or zero correlation between parent and offspring environment. We found that populations evolving in novel environments that were predictable across generations evolved a positive anticipatory maternal effect, because they required maternal exposure to 25°C to achieve maximum reproduction in that temperature. In contrast, populations evolving under zero environmental correlation had lost this anticipatory maternal effect. Similar but weaker patterns were found if instead rate‐sensitive population growth was used as a fitness measure. These findings demonstrate that anticipatory parental effects evolve in response to environmental change so that ill‐fitting parental effects can be rapidly lost. Evolution of positive anticipatory parental effects can aid population viability in rapidly changing but predictable environments.

The First 100 Days of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Control in Vietnam.

BackgroundOne hundred days after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in Vietnam on 23 January, 270 cases were confirmed, with no deaths. We describe the control measures used by the government and their relationship with imported and domestically acquired case numbers, with the aim of identifying the measures associated with successful SARS-CoV-2 control.MethodsClinical and demographic data on the first 270 SARS-CoV-2 infected cases and the timing and nature of government control measures, including numbers of tests and quarantined individuals, were analyzed. Apple and Google mobility data provided proxies for population movement. Serial intervals were calculated from 33 infector-infectee pairs and used to estimate the proportion of presymptomatic transmission events and time-varying reproduction numbers.ResultsA national lockdown was implemented between 1 and 22 April. Around 200 000 people were quarantined and 266 122 reverse transcription polymerase chain reaction (RT-PCR) tests conducted. Population mobility decreased progressively before lockdown. In total, 60% (163/270) of cases were imported; 43% (89/208) of resolved infections remained asymptomatic for the duration of infection. The serial interval was 3.24 days, and 27.5% (95% confidence interval [CI], 15.7%-40.0%) of transmissions occurred presymptomatically. Limited transmission amounted to a maximum reproduction number of 1.15 (95% CI, .·37–2.·36). No community transmission has been detected since 15 April.ConclusionsVietnam has controlled SARS-CoV-2 spread through the early introduction of mass communication, meticulous contact tracing with strict quarantine, and international travel restrictions. The value of these interventions is supported by the high proportion of asymptomatic and imported cases, and evidence for substantial presymptomatic transmission.