Mapping the Genes for Susceptibility and Response to Leishmania tropica in Mouse

Background

L. tropica can cause both cutaneous and visceral leishmaniasis in humans. Although the L. tropica-induced cutaneous disease has been long known, its potential to visceralize in humans was recognized only recently. As nothing is known about the genetics of host responses to this infection and their clinical impact, we developed an informative animal model. We described previously that the recombinant congenic strain CcS-16 carrying 12.5% genes from the resistant parental strain STS/A and 87.5% genes from the susceptible strain BALB/c is more susceptible to L. tropica than BALB/c. We used these strains to map and functionally characterize the gene-loci regulating the immune responses and pathology.

Methods

We analyzed genetics of response to L. tropica in infected F₂ hybrids between BALB/c×CcS-16. CcS-16 strain carries STS-derived segments on nine chromosomes. We genotyped these segments in the F₂ hybrid mice and tested their linkage with pathological changes and systemic immune responses.

Principal Findings

We mapped 8 Ltr (Leishmania tropica response) loci. Four loci (Ltr2, Ltr3, Ltr6 and Ltr8) exhibit independent responses to L. tropica, while Ltr1, Ltr4, Ltr5 and Ltr7 were detected only in gene-gene interactions with other Ltr loci. Ltr3 exhibits the recently discovered phenomenon of transgenerational parental effect on parasite numbers in spleen. The most precise mapping (4.07 Mb) was achieved for Ltr1 (chr.2), which controls parasite numbers in lymph nodes. Five Ltr loci co-localize with loci controlling susceptibility to L. major, three are likely L. tropica specific. Individual Ltr loci affect different subsets of responses, exhibit organ specific effects and a separate control of parasite load and organ pathology.

Conclusion

We present the first identification of genetic loci controlling susceptibility to L. tropica. The different combinations of alleles controlling various symptoms of the disease likely co-determine different manifestations of disease induced by the same pathogen in individual mice.     

The antitumor activity of hydrophobin SC3, a fungal protein

The use of mushroom extracts has been common practice in traditional medicine for centuries, including the treatment of cancer. Proteins called hydrophobins are very abundant in mushrooms. Here, it was examined whether they have antitumor activity. Hydrophobin SC3 of Schizophyllum commune was injected daily intraperitoneally starting 1 day after tumor induction in two tumor mouse models (sarcoma and melanoma). SC3 reduced the size and weight of the melanoma significantly, but the sarcoma seemed not affected. However, microscopic analysis of the tumors 12 days after induction revealed a strong antitumor effect of SC3 on both tumors. The mitotic activity of the tumor decreased 1.6- (melanoma) to 2.3-fold (sarcoma), while the vital mass decreased 2.3- (melanoma) to 4.3-fold (sarcoma) compared to the control. Treatment did not cause any signs of toxicity. Behavior, animal growth, and weight of organs were similar to animals injected with vehicle, and no histological abnormalities were found in the organs. In vitro cell culture studies revealed no direct cytotoxic effect of SC3 towards sarcoma cells, while cytotoxic activity was observed towards melanoma cells at a high SC3 concentration. Daily treatment with SC3 did not result in detectable levels of anti-SC3 antibodies in the plasma. Instead, a cellular immune response was observed. Incubation of spleen cells with SC3 resulted in a 1.5- to 2.5-fold increase in interleukin-10 and TNF-α mRNA levels. In conclusion, the nontoxic fungal hydrophobin SC3 showed tumor-suppressive activity possibly via immunomodulation and may be of benefit as adjuvant in combination with chemotherapy and radiation.     

Cold-active enzymes studied by comparative molecular dynamics simulation

Enzymes from cold-adapted species are significantly more active at low temperatures, even those close to zero Celsius, but the rationale of this adaptation is complex and relatively poorly understood. It is commonly stated that there is a relationship between the flexibility of an enzyme and its catalytic activity at low temperature. This paper gives the results of a study using molecular dynamics simulations performed for five pairs of enzymes, each pair comprising a cold-active enzyme plus its mesophilic or thermophilic counterpart. The enzyme pairs included α-amylase, citrate synthase, malate dehydrogenase, alkaline protease and xylanase. Numerous sites with elevated flexibility were observed in all enzymes; however, differences in flexibilities were not striking. Nevertheless, amino acid residues common in both enzymes of a pair (not present in insertions of a structure alignment) are generally more flexible in the cold-active enzymes. The further application of principle component analysis to the protein dynamics revealed that there are differences in the rate and/or extent of opening and closing of the active sites. The results indicate that protein dynamics play an important role in catalytic processes where structural rearrangements, such as those required for active site access by substrate, are involved. They also support the notion that cold adaptation may have evolved by selective changes in regions of enzyme structure rather than in global change to the whole protein. Figure Collective motions in C^α atoms of the active site of cold-active xylanase Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

A new rodent species of the genus Mus (Rodentia: Muridae) confirms the biogeographical uniqueness of the isolated forests of southern Ethiopia

Organisms Diversity & Evolution - The Ethiopian highlands represent the largest part of the Eastern Afromontane Biodiversity Hotspot (EAMBH). Their fauna and flora are largely unique....     

Occurrence of<Emphasis Type="Italic">penicillium expansum</Emphasis> and patulin in apples as raw materials for processing of foods — case study

The contamination of apples Gloster variety withPenicillium expansum was investigated in the case study. The apples serve as a raw material in thefood industry for processing of baby foodstuffs and other apple products. The core of 3 – 5 % apple samples has been contaminated with spores and mycelium of untested microfungi. The surface tissue of stored apples has not been damaged. Penicillium expansum was isolated in all tested apple samples. Patulin has been found at levels tens to hundreds of üg/kg in tested apple samples. Patulin was primarily associated with core and areas of decomposing tissue and can penetrate up to approx. 1 cm of the surrounding healthy tissue. The production of patulin after the experimental contamination of apples was tested after 14 days of storage (21 °C, dark). The maximum value of patulin was found 110 mg/kg of rotten part of apple sample.     

Computer literacy enhancement in the Teaching Hospital Olomouc. Part I: project management techniques. Short communication

Information explosion and globalization make great demands on keeping pace with the new trends in the healthcare sector. The contemporary level of computer and information literacy among most health care professionals in the Teaching Hospital Olomouc (Czech Republic) is not satisfactory for efficient exploitation of modern information technology in diagnostics, therapy and nursing. The present contribution describes the application of two basic problem solving techniques (brainstorming, SWOT analysis) to develop a project aimed at information literacy enhancement.     

Across-species patterns of genetic variation in forest trees of Central Europe

The study focuses on geographical patterns of genetic variation at allozyme loci common for four main tree species of Central Europe (Norway spruce, silver fir, common beech and sessile oak). Moving-window averaging of four indicators of allelic richness and diversity (proportion of polymorphic loci, mean number of alleles per locus, effective number of alleles and expected heterozygosity) with window size of 50 × 50 km was used to identify the patterns. Moreover, local genetic divergence was assessed using the G _ST (Nei, Molecular population genetic and evolution, Amsterdam and Oxford, North-Holland, 1975) and D _j (Gregorius and Roberds, Theor Appl Genet 71:826–834, 1986) statistics for common beech and silver fir, where raw genotype data were available. Spatial patterns of diversity and allelic richness were quite similar. Romanian Carpathians were identified as the most important hotspot of genetic diversity and evolutionary divergence in Central Europe. Implications for genetic conservation are briefly discussed.     

In vivo and in vitro assessment of brain bioenergetics in aging rats

Brain energy disorders can be present in aged men and animals. To this respect, the mitochondrial and free radical theory of aging postulates that age‐associated brain energy disorders are caused by an imbalance between pro‐ and anti‐oxidants that can result in oxidative stress. Our study was designed to investigate brain energy metabolism and the activity of endogenous antioxidants during their lifespan in male Wistar rats. In vivo brain bioenergetics were measured using ³¹P nuclear magnetic resonance (NMR) spectroscopy and in vitro by polarographic analysis of mitochondrial oxidative phosphorylation. When compared to the young controls, a significant decrease of age‐dependent mitochondrial respiration and adenosine‐3‐phosphate (ATP) production measured in vitro correlated with significant reduction of forward creatine kinase reaction (kfor) and with an increase in phosphocreatine (PCr)/ATP, PCr/Pi and PME/ATP ratio measured in vivo. The levels of enzymatic antioxidants catalase, GPx and GST significantly decreased in the brain tissue as well as in the peripheral blood of aged rats. We suppose that mitochondrial dysfunction and oxidative inactivation of endogenous enzymes may participate in age‐related disorders of brain energy metabolism.