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The Plasmodium falciparum merozoite surface protein MSPDBL2 is a polymorphic antigen targeted by acquired immune responses, and normally expressed in only a minority of mature schizonts. The potential relationship of MSPDBL2 to sexual commitment is examined, as variable mspdbl2 transcript levels and proportions of MSPDBL2-positive mature schizonts in clinical isolates have previously correlated with levels of many sexual stage parasite gene transcripts, although not with the master regulator ap2-g. It is demonstrated that conditional overexpression of the gametocyte development protein GDV1, which promotes sexual commitment, also substantially increases the proportion of MSPDBL2-positive schizonts in culture. Conversely, truncation of the gdv1 gene is shown to prevent any expression of MSPDBL2. However, across diverse P. falciparum cultured lines, the variable proportions of MSPDBL2 positivity in schizonts do not correlate significantly with variable gametocyte conversion rates, indicating it is not involved in sexual commitment. Confirming this, examining a line with endogenous hemagglutinin-tagged AP2-G showed that the individual schizonts expressing MSPDBL2 are mostly different from those expressing AP2-G. Using a selection-linked integration system, modified P. falciparum lines were engineered to express an intact or disrupted version of MSPDBL2, showing the protein is not required for sexual commitment or early gametocyte development. Asexual parasite multiplication rates were also not affected by expression of either intact or disrupted MSPDBL2 in a majority of schizonts. Occurring alongside sexual commitment, the role of the discrete MSPDBL2-positive schizont subpopulation requires further investigation in natural infections where it is under immune selection. IMPORTANCE: Malaria parasites in the blood are remarkably variable, able to switch antigenic targets so they may survive within humans who have already developed specific immune responses. This is one of the challenges in developing vaccines against malaria. MSPDBL2 is a target of naturally acquired immunity expressed in minority proportions of schizonts, the end stages of each 2-day replication cycle in red blood cells which contain merozoites prepared to invade new red blood cells. Results show that the proportion of schizonts expressing MSPDBL2 is positively controlled by the expression of the regulatory gametocyte development protein GDV1. It was previously known that expression of GDV1 leads to increased expression of AP2-G which causes parasites to switch to sexual development, so a surprising finding here is that MSPDBL2-positive parasites are mostly distinct from those that express AP2-G. This discrete antigenic subpopulation of mostly asexual parasites is regulated alongside sexually committed parasites, potentially enabling survival under stress conditions.

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Salix myrtilloides L. is a relict species, threatened with extinction in many European countries. To prevent the loss of the species, tissue culture was established to produce plant material for reintroduction in natural habitats. Micropropagation was chosen as a method to obtain new plants. S. myrtilloides shoots were disinfected with NaOCl, AgNO3, or with a two-step disinfection with NaOCl, and then placed on MS medium supplemented with BA at 1 mg·dm-3 and IBA at 0.1 mg·dm-3. Regenerated shoots were cultivated in presence of BA, KIN, and 2iP to select the treatment with the highest multiplication rate. The obtained plants were acclimatized to ex vitro conditions. Inter-simple sequence repeat (ISSR) and flow cytometric analyses were conducted on in vitro regenerated plants to check their genetic stability. The best disinfection results were obtained when explants were treated with 1.5% NaOCl for 20 min. The highest multiplication rate and good quality plants were noted in the control media, without growth regualtors and in presence of kinetin at 0.5 mg·dm-3. Flow cytometry and ISSR analyses confirmed genetic stability in plantlets, which indicated the possibility to use the in vitro obtained plants for reintroduction.

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Meloidogyne spp. are an important threat to horticulture and cause substantial yield losses. Plant resistance is an alternative control method for chemical nematicides. This study highlights the host suitability of the lettuces cultivars Grand Rapids and Salinas 88 and the beans cultivars Aporé, Cornell 49242, Macarrão Atibaia and Ouro Negro to four Meloidogyne incognita and seven M. javanica isolates from Spain in a pot experiment. Moreover, the response of these cultivars to increasing M. incognita densities (Pi) was assessed in a plastic greenhouse. The lettuce cultivar Regina 71 and the bean cultivar Bolinha were included as susceptible standards for comparison. It was found that Grand Rapids and Salinas 88 lettuces were resistant to the most nematode isolates in the pot experiment but were classified as slightly and moderately resistant, respectively, in the plastic greenhouse at increasing Pi. Regarding the beans, Aporé was resistant to the majority of the Meloidogyne isolates whereas Macarrão Atibaia and Ouro Negro were slightly resistant and Cornell 49242 was susceptible in the pot experiment. In the plastic greenhouse, Aporé was the only cultivar able to effectively suppress the nematode reproduction irrespective of Pi, while Ouro Negro became less resistant as Pi increased. These results play an important role in enhancing the effective and ecofriendly Meloidogyne management strategies.

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In order to explore the optimal timing for initiating cytoreduction chemotherapy following all-trans retinoic acid plus arsenic trioxide administration, 58 newly diagnosed patients with acute promyelocytic leukemia (APL) with low-intermediate mortality risk were retrospectively analyzed. During induction treatment, white blood cell (WBC) count >4x109/l and multiplication rate of WBC <3 days were defined as rapid WBC multiplication. Patients were divided into two groups: With or without rapid WBC multiplication. Comparison between the two groups revealed that the incidence of differentiation syndrome (DS) (48.1% vs. 6.5%; P<0.001), grade 3-4 bleeding (34.8% vs. 6.5%; P=0.022) and peak WBC count (30.4±20.0x109/l vs. 8.67±5.4x109/l; P<0.001) were significantly higher in the group with rapid WBC multiplication compared with in the group without rapid WBC multiplication. No significant differences were observed in bone marrow depression, infection, complete remission (CR) rate, time to achieve CR and early mortality rate between the two groups. Multivariate analysis revealed that WBC count at chemotherapy initiation was an independent risk factor for the occurrence of DS (P=0.040). Peak WBC count and rapid WBC multiplication were significantly associated with grade 3-4 bleeding (P=0.019 and P=0.002, respectively). Hence, WBC count at chemotherapy initiation along with its multiplication rate may direct the timing of cytoreduction chemotherapy during induction treatment in newly diagnosed APL with low-intermediate risk.

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The current situation with the SARS-CoV-2 pandemic indicates the importance of new approaches in vaccine design. In order to design new attenuated vaccines, to decrease virulence of virus wild types, it is important to understand what allows a virus to hijack its host cell's metabolism, a property of all viruses. RNA and protein sequences obtained from databases were used to count the number of atoms of each element in the virions of SARS, MERS and SARS-CoV-2. The number of protein copies and carbohydrate composition were taken from the literature. The number of lipid molecules was estimated from the envelope surface area. Based on elemental composition, growth equations were balanced, and thermodynamic properties of the viruses were determined using Patel-Erickson and Battley equations. Elemental and molecular compositions of SARS, MERS and SARS-CoV-2 were found, as well as their standard thermodynamic properties of formation and growth. Standard Gibbs energy of growth of virus nucleocapsids was found to be significantly more negative than that of their host tissue. The ratio of Gibbs energies of growth of virus nucleocapsids and host cell is greater than unity. The more negative Gibbs energy of growth of viruses implies that virus multiplication has a greater driving force than synthesis of host cell components, giving a physical explanation of why viruses are able to hijack their host cell's metabolism. Knowing the mechanism of viral metabolism hijacking can open new paths for vaccine design. By manipulating chemical composition of viruses, virulence can be decreased by making the Gibbs energy of their growth less negative, resulting in decreased multiplication rate, while preserving antigenic properties.

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The benefits of in vitro plant cultivation are mainly due to very high multiplication rate. Cultivation of plant material in vitro can be carried out during the whole year regardless of the time of the year or weather conditions. We create artificial conditions in the lab (heat, light, humidity), and we can regulate these conditions at any time. For the preservation of cultivar identity, we recommend establishing in vitro cultures from shoot tips usually larger than 0.2 mm. In practice, in vitro cultivation of plants uses these growth regulators to achieve organogenesis, for example, root formation, prolonged growth, or multiplication. During each subculture, these cultures are then transferred on a solid agar medium in the form of actively growing multiple shoots with a well-differentiated shoot tip containing meristematic area. Cytokinins are important for cell division and causes branching of plants. Auxins, both endogenous and exogenous, act at as a trigger for the differentiation and formation of root primordia. Morphological characteristics (formation of leaves or callus) and shoot development should be observed during in vitro multiplication and after transfer to ex vitro conditions.

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The temporary immersion system (TIS) is being used with tremendous success for automation of micropropagation of many plant species. TIS usually consists of a culture vessel comprising two compartments, an upper one with the plant material and a lower one with the liquid culture medium and an automated air pump. The latter enables contact between all parts of the explants and the liquid medium by setting overpressure to the lower part of the container. These systems are providing the most satisfactory conditions for date palm regeneration via shoot organogenesis and allow a significant increase of multiplication rate (5.5-fold in comparison with that regenerated on agar-solidified medium) and plant material quality, thereby reducing production cost.

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Patients presenting with severe falciparum malaria in a Bangladeshi tertiary hospital had higher total parasite burden, estimated by parasitemia and plasma PfHRP2, than uncomplicated malaria patients despite shorter fever duration. This suggests that higher parasite multiplication rates (PMR) contribute to causing the higher biomass found in severe disease. Compared with patients without a history of previous malaria, patients with previous malaria carried a lower parasite biomass with similar fever duration at presentation, suggesting that host immunity reduces the PMR.

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Protein export is considered an essential feature of malaria parasite blood stage development. Here, we examined five components of the candidate Plasmodium translocon of exported proteins (PTEX), a complex thought to mediate protein export across the parasitophorous vacuole membrane into the host cell. Using the murine malaria model parasite Plasmodium berghei, we succeeded in generating parasite lines lacking PTEX88 and thioredoxin 2 (TRX2). Repeated attempts to delete the remaining three translocon components failed, suggesting essential functions for EXP2, PTEX150, and heat shock protein 101 (HSP101) during blood stage development. To analyze blood infections of the null-mutants, we established a flow cytometry-assisted intravital competition assay using three novel high fluorescent lines (Bergreen, Beryellow, and Berred). Although blood stage development of parasites lacking TRX2 was affected, the deficit was much more striking in PTEX88 null-mutants. The multiplication rate of PTEX88-deficient parasites was strongly reduced resulting in out-competition by wild-type parasites. Endogenous tagging revealed that TRX2::tag resides in distinct punctate organelles of unknown identity. PTEX88::tag shows a diffuse intraparasitic pattern in blood stage parasites. In trophozoites, PTEX88::tag also localized to previously unrecognized extensions reaching from the parasite surface into the erythrocyte cytoplasm. Together, our results indicate auxiliary roles for TRX2 and PTEX88 and central roles for EXP2, PTEX150, and HSP101 during P. berghei blood infection.

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Seasonal multiplication and overwinter survival are density-dependent in Heterodera glycines. At low to moderate population densities, the nematode is capable of large population increases on susceptible soybean cultivars and high rates of oversummer or overwinter survival in the absence of a host. To improve estimates of H. glycines multiplication and survival rates, egg densities were monitored for 12 cropping sequences across 10 years. Log-linear regression analysis was used to describe and compare density-dependent relationships. Growing-season change in H. glycines egg densities was density-dependent for all crops (susceptible soybean, resistant soybean, and nonhost), with slope estimates for the density-dependent relationship greater for susceptible soybean compared with a non-host crop. Overwinter population change also was density-dependent, with similar declines in survival rates observed for all crops as population densities increased. Survival was greater following susceptible soybean compared with resistant soybean, with an intermediate rate of survival associated with non-host crops. Survival estimates greater than 100% frequently were obtained at low population densities, despite attempts to account for sampling error. Rates of growing-season multiplication and survival, when standardized for population density, declined with year of the study. Standardized overwinter survival rates were inversely related to average daily minimum temperature and monthly snow cover.

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Shoot proliferation was obtained from shoot tip and nodal bud explants ofSyzygium alternifolium (Wight) walp on modified Murashige and Skoogs medium (MS) supplemented with either BA, KN or AD alone or BA in combination with either IAA, NAA or IBA. A combination of BA and auxins produced more shoots from both types of explants than on the medium containing only cytokinins. The highest multiplication rate was achieved with nodal bud explants in presence of 17.7µM BA and 2.6µM NAA. Excised shoots were rooted on half-strength MS medium with either IAA or IBA. The regenerated plantlets have been successfully acclimatized and transferred to soil. About 70% of plantlets have survived underex vitro conditions.

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Nematode multiplication rates Pf/Pi and overwinter survivorship (Pi2/Pfl) for Meloidogyne incognita were both adequately described by negative exponential models, indicating density dependence in each case. Density dependence of the multiplication rates is mediated by resource limitation and host damage; in survivorship rates it may be mediated by limitation of stored reserves or prevalence of antagonists. Parameters of multiplication rate models were crop specific and varied with host status and environmental suitability. Maximum multiplication rates (a) of nearly 1,000 were measured for tomatoes. Equilibrium densities were sensitive to tolerance of the nematode by the crop. Overwinter survival rates varied among locations where cultural practices and length of infestation time differed.