In Vitro Culture,Drug Sensitivity,and Transcriptome of Plasmodium Vivax Hypnozoites

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Usefulness of the recombinant liver stage antigen-3 for an early serodiagnosis of Plasmodium falciparum infection

In order to develop tools for an early serodiagnosis of Plasmodium falciparum infection, we evaluated the usefulness of P. falciparum liver stage antigen-3 (LSA-3) as a serodiagnostic antigen. A portion of LSA-3 gene was cloned, and its recombinant protein (rLSA-3) was expressed in Escherichia coli and purified by column chromatography. The purified rLSA-3 and 120 test blood/serum samples collected from inhabitants in malaria-endemic areas of Mandalay, Myanmar were used for this study. In microscopic examinations of blood samples, P. falciparum positive rate was 39.1% (47/120) in thin smear trials, and 33.3% (40/120) in thick smear trials. Although the positive rate associated with the rLSA-3 (30.8%) was lower than that of the blood stage antigens (70.8%), rLSA-3 based enzyme-linked immunosorbent assay could detect 12 seropositive cases (10.0%), in which blood stage antigens were not detected. These results indicate that the LSA-3 is a useful antigen for an early serodiagnosis of P. falciparum infection.     

High levels of antibodies to Plasmodium falciparum liver stage antigen-1 in naturally infected individuals in Myanmar

Plasmodium falciparum liver stage antigen-1 (PfLSA-1) is one of the few antigens expressed exclusively in liver stage parasites. In this study, we evaluated the antibody responses against recombinant PfLSA-1 in naturally infected individuals in Myanmar. High levels of antibody responses (70.7%) were detected in 82 serum samples from 116 infected individuals, and IgG responses to PfLSA-1 principally composed of responses of IgG1 and IgG3 subclasses. These results show that PfLSA-1 elicits effective antibody responses in individuals infected with P. falciparum, and thus it could be not only an attractive candidate protein for vaccine development, but also a useful antigen for serodiagnosis of the infection.     

The ABSCISIC ACID-INSENSITIVE 3 (ABI3) gene is expressed during vegetative quiescence processes in Arabidopsis

The ABSCISIC ACID-INSENSITIVE 3 ( ABI3 ) gene of Arabidopsis thaliana (L.) Heynh is known to play an important role during seed maturation and dormancy. Here, we present evidence suggesting an additional role for ABI3 during vegetative quiescence processes. During growth in the dark, ABI3 is expressed in the apex of the seedlings after cell division is arrested. The 2S seed storage protein gene, a target gene of ABI3 in seeds, is also induced in the arrested apex under similar darkness conditions. In addition, β -glucuronidase expression under the control of the ABI3 promoter is abolished by treatments that provoke leaf development in the dark [sucrose and abscisic acid (ABA) biosynthesis inhibitors] and induced by treatments that prevent leaf development (darkness and ABA). Furthermore, ABI3 expression is absent in apices of dark-grown de-etiolated ( det 1 ) and abi3 mutants, both known to develop leaves or leaf primordia in the dark. The fact that the expression of the ABI3 gene is only observed in a fraction of the analysed plants suggests that ABI3 is probably only one of the components of a molecular network underlying quiescence. In addition to the expression of ABI3 in apices of dark-grown seedlings, the ABI3 promoter confers expression in other vegetative organs as well, such as the stipules and the abscission zones of the siliques. In conclusion, apart from its role in seed development, ABI3 might have additional functions.     

Listr1遗传位点影响小鼠对约氏疟原虫易感性的研究

探讨Listr1遗传位点影响小鼠对疟原虫易感性的可能性及其初步作用机制。致死型约氏疟原虫(Plasmodiumyoelii17XL,P.y17XL)感染C.B6By-Listr1小鼠(BALB/c小鼠基因背景下引入C57BL/6小鼠Lis-tr1遗传位点的同类系小鼠)和BALB/c小鼠,分析二者生存率和感染率的差异;HE染色分析P.y17XL感染后第5天C.B6By-Listr1小鼠和BALB/c小鼠肝脏组织损伤情况;定量PCR法检测P.y17XL感染后小鼠肝脏组织第1、2、5天IL-1β、IL-6、TNF-α、IFN-γ的表达含量。结果显示,P.y17XL感染后4~8dC.B6By-Listr1小鼠虫血症水平显著高于BALB/c小鼠(P<0.05)。C.B6By-Listr1小鼠于感染后7~9d全部死亡;而半数BALB/c小鼠于感染后8~9d死亡,其余BALB/c小鼠至感染后第13天仍存活,两种小鼠生存率差异具有统计学意义(P<0.01)。C.B6By-Listr1小鼠P.y17XL感染后第5天肝组织HE染色可见到明显的疟色素沉积;而BALB/c小鼠全片基本未见到疟色素的沉积。P.y17XL感染后第2天BALB/c小鼠肝组织IL-6(P<0.05)、TNF-α(P<0.05)mRNA水平显著高于C.B6By-Listr1小鼠。结果表明Listr1遗传位点可以影响小鼠对疟原虫的易感性,与肝脏固有免疫相关。     

Effect of Soil Water Potential on Survival of Meloidogyne javanica in Fallow Soil

A natural infestation of Meloidogyne javanica in an aggregated Oxisol declined at an exponential rate when aliquots of the soil were stored for 72 days in polyethylene bags at various soil water potentials (Ψ). Time periods required for reduction in soil infestations by 50% were 2.7, 4.9, 110, 10, and 2.6 days at Ψ of -0.16, -0.30, -1.1, -15, and -92 bars, respectively. In the wetter soils, at Ψ of -0.16, -0.30, and -1.1 bars, the predominant stage recovered was the second-stage larva. In the drier soils, at Ψ of -15 and -92 bars, both eggs and larvae were recovered with neither stage predominating. Incidence of coiled larvae was inversely related to the Ψ value of the soil, a greater incidence occurring in the drier soils. After 15-32 days, percentages of coiled larvae were 13, 27, 55, 65, and 88% in soil at Ψ of -0.17, -0.60, -1.9, -15, and -82 bars, respectively.     

Proteolysis of a 34 kDa Phosphoprotein Coincident with a Decrease in Protein Kinase Activity During the Erythrocytic Schizont Stage of the Malaria Parasite

ABSTRACT. Protein phosphorylation events may play important roles in the replication and differentiation of the malarial parasite. Investigations into the lability of a Plasmodium protein kinase revealed that a 34 kDa parasite phosphoprotein is rapidly converted into a 19 kDa fragment. Coincident with this conversion is a nearly total loss of a protein kinase activity, as determined from the phosphorylation of endogenous protein substrates. Both the conversion of the 34 kDa protein to the 19 kDa protein and the loss of protein kinase activity are inhibited by thio-protease inhibitors. The presence of low levels of the intact 34 kDa protein restores the protein kinase activity to almost maximum levels. However, it was not possible to demonstrate protein kinase activity associated with the 34 kDa protein, thus suggesting that the 34 kDa protein is probably an activator or regulator of the protein kinase activity and not a protein kinase. The conversion to the 19 kDa fragment also occurs in vivo and only during the schizont stage prior to the appearance of ring forms. During this same period the protein kinase activity decreases suggesting that the proteolytic processing of the 34 kDa protein may be a physiological regulator of the protein kinase.     

Quiescence: early evolutionary origins and universality do not imply uniformity

Cell cycle investigations have focused on relentless exponential proliferation of cells, an unsustainable situation in nature. Proliferation of cells, whether microbial or metazoan, is interrupted by periods of quiescence. The vast majority of cells in an adult metazoan lie quiescent. As disruptions in this quiescence are at the foundation of cancer, it will be important for the field to turn its attention to the mechanisms regulating quiescence. While often presented as a single topic, there are multiple forms of quiescence each with complex inputs, some of which are tied to conceptually challenging aspects of metazoan regulation such as size control. In an effort to expose the enormity of the challenge, I describe the differing biological purposes of quiescence, and the coupling of quiescence in metazoans to growth and to the structuring of tissues during development. I emphasize studies in the organism rather than in tissue culture, because these expose the diversity of regulation. While quiescence is likely to be a primitive biological process, it appears that in adapting quiescence to its many distinct biological settings, evolution has diversified it. Consideration of quiescence in different models gives us an overview of this diversity.