Slow clearance of Plasmodium vivax with chloroquine amongst children younger than six months of age in the Brazilian Amazon

Plasmodium vivax is the most widespread parasite causing malaria, being especially prevalent in the Americas and Southeast Asia. Children are one of the most affected populations, especially in highly endemic areas. However, there are few studies evaluating the therapeutic response of infants with vivax malaria. This study retrospectively evaluated the parasitaemia clearance in children diagnosed with vivax malaria during the first five days of exclusive treatment with chloroquine (CQ). Infants aged less than six months old had a significantly slower parasitaemia clearance time compared to the group of infants and children between six months and 12 years old (Kaplan-Meier survival analysis; Wilcoxon test; p = 0.004). The impaired clearance of parasitaemia in younger children with vivax malaria is shown for the first time in Latin America. It is speculated that CQ pharmacokinetics in young children with vivax malaria is distinct, but this specific population may also allow the detection of CQ-resistant parasites during follow-up, due to the lack of previous immunity.     

Role of nitrogen metabolism in the development of salt tolerance in barley plants

The 7- to 8-day-old barley (Hordeum vulgare L.) seedlings grown in KNO3 solutions (1-40 mM) were characterized by the substrate activation of nitrate reductase (NR) in the apical leaf segments (1–2 cm in length), as well as by stimulated growth, broadened leaf blades, and by vigorously developed system of shortened roots. When the seedlings were grown in the presence of 20 mM KNO₃, the ability of leaf segments to generate superoxide anion radical remained at the level typical of control plants grown in water. The content of 5-aminolevulinic acid (ALA) in plants grown in the presence of 20 mM KNO₃ was 2.2–2.4 times higher than in control plants. The plants grown in the presence of nitrate had an elevated content of chlorophylls a and b, heme, and protein (by 42%). At the same time, the proline content was almost twofold lower than in control plants, which was due to substantial reduction (by 40%) in activity of Δ¹-pyrroline-5-carboxylate synthetase (P5CS). It is concluded that the substrate activation of NR by KNO₃ under normal growth conditions results in predominant utilization of glutamic acid (the primary product of inorganic nitrogen assimilation) for biosynthesis of tetrapyrroles and protein amino acids at the expense of inhibition of proline synthesis. When barley seedlings were grown in 150 mM NaCl solution, the plant growth and the root system development were suppressed to the levels of 63 ± 6% and 61 ± 11% of the control values, respectively. In the apical leaf tissues of plants adapted to NaCl, there was a slight decrease in the total NR activity (by 10%), a significant reduction in protein content (by 32%), and a parallel increase in the content of ALA (by a factor of 4.3), chlorophylls, heme, carotenoids, proline (2.2-fold) and P5CS (1.6-fold) with respect to the control values. It is proposed that the accumulation of ALA and proline under salinity-induced suppression of nitrogen assimilation results from the predominant allocation of glutamate for biosyntheses of ALA and proline at the expense of inhibition of growth-related processes requiring intense protein synthesis. The substrate activation of NR by KNO₃ under salinity conditions was associated with prevailing allocation of the assimilated nitrogen for synthesis of proline and protein amino acids, which reinforced plant cell protection against salinity and stimulated plant growth.     

Improving the analysis of designed studies by combining statistical modelling with study design information

Background  

In the fields of life sciences, so-called designed studies are used for studying complex biological systems. The data derived from these studies comply with a study design aimed at generating relevant information while diminishing unwanted variation (noise). Knowledge about the study design can be used to decompose the total data into data blocks that are associated with specific effects. Subsequent statistical analysis can be improved by this decomposition if these are applied on selected combinations of effects.     

Double-strand break repair in bacteriophage T4: recombination effects of 3'-5' exonuclease mutations

The role of 3'-5' exonucleases in double-strand break (DSB)-promoted recombination was studied in crosses of bacteriophage T4, in which DSBs were induced site specifically within the rIIB gene by SegC endonuclease in the DNA of only one of the parents. Frequency of rII+ recombinants was measured in two-factor crosses of the type i x ets1, where ets1 designates an insertion in the rIIB gene carrying the cleavage site for SegC and i's are rIIB or rIIA point mutations located at various distances (12-2040 bp) from the ets1 site. The frequency/distance relationship was obtained in crosses of the wild-type phage and dexA1 (deficiency in deoxyribonuclease A), D219A (deficiency in the proofreading exonuclease of DNA polymerase), and tsL42 (antimutator allele of DNA polymerase) mutants. In all the mutants, recombinant frequency in crosses with the i-markers located at 12 and 33 bp from ets1 was significantly enhanced, implying better preservation of 3'-terminal sequences at the ends of the broken DNA. The effects of dexA1 and D219A were additive, suggesting an independent action of the corresponding nucleases in the DSB repair pathway. The recombination enhancement in the dexA1 mutant was limited to short distances (<100 bp from ets1), whereas in the D219A mutant a significant enhancement was seen at all the tested distances. From the character of the frequency/distance relationship, it is inferred that the synthesis-dependent strand-annealing pathway may operate in the D219A mutant. The recombination-enhancing effect of the tsL42 mutation could be explained by the hypothesis that the antimutator 43Exo removes a shorter stretch of paired nucleotides than the wild-type enzyme does during hydrolysis of the unpaired terminus in the D-loop intermediate. The role of the proofreading exonuclease in the formation of a robust replicative fork is discussed.     

Molecular phylogenetic study of the systematic position of Baikalian oligochaetes in the system Clitellata

Phylogenetic relationships within the class Clitellata were examined using nucleotide sequences of nuclear 18S ribosomal RNA gene fragments. In the analysis, the already determined sequences for the individual species representing the class members Hirudinea, Acanthobdellida, Branchiobdellida, and Oligochaeta were included. Furthermore, newly determined sequences of the thirteen representatives of the family Lumbriculidae. including 12 Baikalian endemic species, were analyzed. The hypothesis on the close relatedness of these four groups of Clitellata was supported. Leeches, branchiobdellidans, and lumbriculides form three independent parallel branches of evolution. These results were consistent with the hypothesis on the role of the family Lumbriculidae as a connecting link, or the transition form between the parasitic and free-living groups of Clitellata. At the same time, these data refute the suggestion that Lumbriculidae could be the ancestral lineage of other Oligochaeta. Moreover, polymorphic group of Baikalian lumbriculides clustered independently from the other representatives of the family, pointing to the uniqueness of the Baikalian fauna of oligochaetes, which was formed within relatively closed system of this ancient lake.     

Effects of cyanobacterial extracellular products and gibberellic acid on salinity tolerance in Oryza sativa L

The XI International Rotifer Symposium was held during 11–18 March, 2006 at the National Autonomous University of Mexico Campus Iztacala located at the North Mexico City (Mexico). These triennial international meetings, first organized in Austria by Late Ruttner-Kolisko in September 1976, are gradually becoming the focal point of discussion and collaboration from rotifer workers across the world. The present XI symposium was attended by 125 participants from 20 nations. During this meeting, different themes of rotifer research from morphology to molecular biology were considered. In addition, there were four invited lectures and four workshops covering different themes of the symposium. During the last 30 years, rotifer research has witnessed gradual shift from the conventional morphological taxonomy to molecular and evolutionary systematics. While the basic rotifer ecological studies continue today, applied areas such as ecotoxicology and aquaculture have taken key roles in the recent meetings. The international rotifer meetings provide ample opportunities not only for exchange of ideas and recent research, but also for material and in establishing inter-personal relationships. Over the last 30 years, the number of participants attending the rotifer meetings has increased.     

Double-strand break repair in bacteriophage T4: coordination of DNA ends and effects of mutations in recombinational genes

Coordination of DNA ends during double-strand break (DSB) repair was studied in crosses of bacteriophage T4 in which DSBs were induced site-specifically by SegC endonuclease in the DNA of only one of the parents. Coupling of the genetic exchanges to the left and to the right of the DSB was measured in the wild-type genetic background as well as in T4 strains bearing mutations in several recombination genes: 47, uvsX, uvsW, 59, 39 and 61. The observed quantitative correlation between the degree of coupling and position of the recombining markers in relation to the DSB point implies that the two variants of the splice/patch-coupling (SPC) pathway, the "sequential SPC" and the "SPC with fork collision", operate during DSB repair. In the 47 mutant with or without a das suppressor, coupling of the exchanges was greatly reduced, indicating a crucial role of the 47/46 complex in coupling of the genetic exchanges on the two sides of the DSB. From the observed dependence of the apparent coupling on the intracellular ratio of breakable and unbreakable chromosomes in different genetic backgrounds it is inferred that linking of the DNA ends by 47/46 protein is the mechanism that accounts for their concerted action during DSB repair. A mechanism of replicative resolution of D-loop intermediate (RR pathway) is suggested to explain the phenomenology of DSB repair in DNA arrest and uvsW mutants. A "left"-"right" bias in the recombinogenic action of two DNA ends of the broken chromosome was observed which was particularly prominent in the 59 (41-helicase loader) and 39 (topoisomerase) mutants. Phage topoisomerase II (gp39-52-60) is indispensable for growth in the DNA arrest mutants: the doubles 47(-)39(-), uvsX 39(-) and 59(-)39(-) are lethal.     

Differentiation of capripoxvirus species and strains by polymerase chain reaction

A fast and simple method for capripoxvirus species identification has been developed. The method is based on multiplex polymerase chain reaction (MPCR) with species-specific primers and does not require nucleotide sequencing or restriction analysis of PCR products. To differentiate vaccine strains used in Russia and countries of the former Soviet Union from epizootic isolates of sheeppox virus, a method based on restriction analysis of the ankyrin-repeat protein gene fragment amplified by PCR has been developed. Being highly specific, both methods may be used for routine diagnosis of capripoxvirus-associated diseases.     

Recombinant non-structural 3A, 3B and 3AB proteins of foot-and-mouth disease virus: use for differentiation of vaccinated and infected cattle

Recombinant proteins 3A, 3B and 3AB were obtained by expression in Escherichia coli and purified by metal-chelate chromatography. The proteins were used as antigens in indirect ELISA to differentiate vaccinated and infected cattle. While testing 200 sera from cattle 3A-ELISA was more sensitive and specific than 3B- and 3AB-ELISA. Compared with "Chekit FMD-3ABC", 3A-ELISA showed the same level of specificity and higher level of sensitivity.     

Bioactive Components in Methyl tert-Butyl Ether Extract of Sea Buckthorn (Hippophae rhamnoides L.) Green Waste

Russian Journal of Bioorganic Chemistry - Lipophilic constituents of sea buckthorn leafy shoots, which is a large-scale waste product of sea buckthorn oil production and rejuvenating pruning of...