In vitro evolution of distinct self-cleaving ribozymes in diverse environments

In vitro evolution experiments have long been used to evaluate the roles of RNA in both modern and ancient biology, and as a tool for biotechnology applications. The conditions under which these experiments have been conducted, however, do not reflect the range of cellular environments in modern biology or our understanding of chemical environments on the early earth, when the atmosphere and oceans were largely anoxic and soluble Fe²⁺ was abundant. To test the impact of environmental factors relevant to RNA''s potential role in the earliest forms of life, we evolved populations of self-cleaving ribozymes in an anoxic atmosphere with varying pH in the presence of either Fe²⁺ or Mg²⁺. Populations evolved under these different conditions are dominated by different sequences and secondary structures, demonstrating global differences in the underlying fitness landscapes. Comparisons between evolutionary outcomes and catalytic activities also indicate that Mg²⁺ can readily take the place of Fe²⁺ in supporting the catalysis of RNA cleavage at neutral pH, but not at lower pH. These results highlight the importance of considering the specific environments in which functional biopolymers evolve when evaluating their potential roles in the origin of life, extant biology, or biotechnology.     

Antimicrobial Properties of a Peptide Derived from the Male Fertility Factor kl2 Protein of Drosophila melanogaster

Antimicrobial peptides (AMPs) are important components of innate immunity. Here, we report the antimicrobial properties of a peptide derived from the Male fertility factor kl2 (MFF-kl2) protein of Drosophila melanogaster, which was identified as a functional analog of the mammalian antibacterial chemerin-p4 peptide. The antimicrobial activity of multifunctional chemerin is mainly associated with a domain localized in the middle of the chemerin sequence, Val66-Pro85 peptide (chemerin-p4). Using bioinformatic tools, we found homologs of the chemerin-p4 peptide in the proteome of D. melanogaster. One of them is MFF-p1, which is a part of the MFF kl2 protein, encoded by the gene male fertility factor kl2 (kl-2) located on the long arm of the Y chromosome. The second detected peptide (Z-p1) is a part of the Zizimin protein belonging to DOCK family, which is involved in cellular signaling processes. After testing the antimicrobial properties of both peptides, we found that only MFF-p1 possesses these properties. Here, we demonstrate its antimicrobial potential both in vitro and in vivo after infecting D. melanogaster with bacteria. MFF-p1 strongly inhibits the viable counts of E. coli and B. subtilis after 2 h of treatment and disrupts bacterial cells. The expression of kl-2 is regulated by exposure to bacteria and by the circadian clock.     

Prevalence of traditional cardiovascular risk factors for coronary artery disease and elevated fibrinogen among active military personnel in Republic of Serbia: A cross-sectional study

BackgroundIt is well known that less than 1% of the population achieves ideal cardiovascular health, and 65% of patients do not have their conventional risk biomarkers under control. Military service has its own particularities that may contribute to cardiovascular risk.MethodsTo define the preventive strategy goals, we analysed the prevalence of traditional cardiovascular risk factors for coronary artery disease and elevated fibrinogen among active military personnel in the Republic of Serbia.ResultsThe cross-sectional study included 738 individuals older than 20 years, mostly between 31 and 40 years old. The mean value of SBP for the whole group was 122.39± 9.42 mmHg, and for the DBP, it was 79.94±6.56 mmHg. Among active military personnel, 72.7% (533) had prehypertension, and 13.8% (101) was hypertensive. Both body mass and BMI index among the observed age subgroups were found to increase with the age of the patients and cholesterol values. HDL cholesterol values also differed statistically significantly between age subgroups, with the proportion of individuals with HDL less than 1.5 mmol/L in all subgroups being about 85%, the only in the 41-50 age group was lower, 76.4%. LDL cholesterol and the proportion of individuals who had LDL 3.5 increases with the age of patients, and an identical trend was recorded with triglycerides. With ageing, fibrinogen levels increased.ConclusionsThose findings considering cardio and cerebrovascular risk factors would help create a new approach for primary prevention for these categories of individuals.     

Combined effects of shade and drought on tulip poplar seedlings: trade‐off in tolerance or facilitation?

It has been hypothesised that many natural plant distribution patterns can be explained by a trade-off between shade and drought tolerance which would make plants more sensitive to shade under dry conditions. On the other hand, shading by nurse plants is often observed to enhance growth and survival of smaller plants in dry areas. This paper describes an experiment designed to address the interactive effects of drought and shade on growth and physiology of tulip poplar seedlings ( Liriodendron tulipifera ) grown in shade houses under different combinations of irradiance (1%, 5%, 12%, 17%, and 27% of ambient PAR) and soil water content (5–9%, 11–15%, and>20%). The results show no evidence that higher PAR levels compensate for the negative effects of drought on photosynthesis and growth. Rather, rates of estimated daily shoot carbon gain decreased with PAR under dry conditions. Daily xylem sapflow patterns indicated that this was associated with a strong reduction in stomatal conductance in plants growing in dry soil and high PAR conditions. Whole-shoot light compensation points were higher for plants raised under higher PAR conditions, but were not significantly influenced by the water treatments. Shoot dark respiration rates decreased under drier conditions. These results do not support the hypothesis of a trade-off between shade and drought tolerance. Instead, they indicate mechanisms that can lead to positive effects of shading by neighbouring plants under dry conditions. Indeed, such facilitation is thought to be important in many plant communities.     

Limited polymorphism of both classes of MHC genes in four different species of the Balkan mole rat

We analyzed the restriction fragment length polymorphism of class I and class II MHC genes in DNA from 20 individuals belonging to the four different species of the complex of species of Balkan mole rats Spalax leucodon captured at four different localities in Yugoslavia. All populations were tested with four restriction enzymes and one conserved mouse probe for each of the two classes of MHC genes. The probes employed detect either limited polymorphism of class I genes or lack of polymorphic bands containing class II genes. Of the two other subterranean rodents that have been studied, four karyotype forms of the Israeli mole rat show polymorphism in both classes of MHC genes similar to the one found in all other mammals (Nieti et al. 1985), and the Syrian hamster shows limited polymorphism of class I genes and high polymorphism of class II genes (McGuire et al. 1985). Balkan mole rats belong to a new group in this respect, different from all mammals studied so far, since they apparently show limited polymorphism of both classes of MHC genes.