Mitochondrial DNA of ancient Cumanians: culturally Asian steppe nomadic immigrants with substantially more western Eurasian mitochondrial DNA lineages

The Cumanians were originally Asian pastoral nomads who in the 13th century migrated to Hungary. We have examined mitochondrial DNA from members of the earliest Cumanian population in Hungary from two archeologically well-documented excavations and from 74 modern Hungarians from different rural locations in Hungary. Haplogroups were defined based on HVS I sequences and examinations of haplogroup-associated polymorphic sites of the protein coding region and of HVS II. To exclude contamination, some ancient DNA samples were cloned. A database was created from previously published mtDNA HVS I sequences (representing 2,615 individuals from different Asian and European populations) and 74 modem Hungarian sequences from the present study. This database was used to determine the relationships between the ancient Cumanians, modern Hungarians, and Eurasian populations and to estimate the genetic distances between these populations. We attempted to deduce the genetic trace of the migration of Cumanians. This study is the first ancient DNA characterization of an eastern pastoral nomad population that migrated into Europe. The results indicate that, while still possessing a Central Asian steppe culture, the Cumanians received a large admixture of maternal genes from more westerly populations before arriving in Hungary. A similar dilution of genetic, but not cultural, factors may have accompanied the settlement of other Asian nomads in Europe.     

Agrobacterium tumefaciens-mediated transformation ofMucor circinelloides

The Agrobacterium tumefaciens-mediated transformation of the zygomycetous fungus Mucor circinelloides is described. A method was also developed for the hygromycin B-based selection of Mucor transformants. Transformation with the hygromycin B phosphotransferase gene of Escherichia coli controlled by the heterologous Aspergillus nidulans trpC promoter resulted in hygromycin B-resistant clones. The presence of the hygromycin resistance gene in the genome of the transformants was verified by polymerase chain reaction and Southern hybridization: the latter analyses revealed integrations in the host genome at different sites in different transformants. The stability of transformants remained questionable during the latter analyses.     

Amine donor protein substrates for transglutaminase activity in Caenorhabditis elegans

Transglutaminase dependent cross-linking of proteins has been implicated in a wide range of biological phenomena occurring in both extracellular and intracellular compartments. Clarification of the physiological role of transglutaminases requires identification of substrate molecules. Here we report the detection, purification, and identification by mass spectrometry of proteins, the glutamate dehydrogenase, a protein disulfide isomerase, and aldehyde dehydrogenase as amine donor substrates for the transglutaminase activity of the nematode Caenorhabditis elegans utilizing a novel biotinylated oligoglutamine peptide as a substrate. We also purified and identified streptavidin-binding proteins of the worm.     

Effect of the sesterterpene-type metabolites, ophiobolins A and B, on zygomycetes fungi

Ophiobolins are sesterterpene-type phytotoxins produced by fungi belonging mainly to the genus Bipolaris. In this study, the antifungal effect of ophiobolins A and B on different zygomycetes has been examined. Depending on the zygomycete tested, MIC values of 3.175-50 μg mL(-1) were found for ophiobolin A and 25-50 μg mL(-1) for ophiobolin B. Ophiobolin A inhibited sporangiospore germination of Mucor circinelloides and caused morphological changes; the fungus formed degenerated, thick or swollen cells with septa. Cytoplasm effusions from the damaged cells were also observed. Fluorescence microscopy after annexin and propidium iodide staining of the treated cells suggested that the drug induced an apoptosis-like cell death process in the fungus.     

Identification of Tail Genes in the Temperate Phage 16-3 of Sinorhizobium meliloti 41

Genes encoding the tail proteins of the temperate phage 16-3 of the symbiotic nitrogen-fixing bacterium Sinorhizobium meliloti 41 have been identified. First, a new host range gene, designated hII, was localized by using missense mutations. The corresponding protein was shown to be identical to the 85-kDa tail protein by determining its N-terminal sequence. Electron microscopic analysis showed that phage 16-3 possesses an icosahedral head and a long, noncontractile tail characteristic of the Siphoviridae. By using a lysogenic S. meliloti 41 strain, mutants with insertions in the putative tail region of the genome were constructed and virion morphology was examined after induction of the lytic cycle. Insertions in ORF017, ORF018a, ORF020, ORF021, the previously described h gene, and hII resulted in uninfectious head particles lacking tail structures, suggesting that the majority of the genes in this region are essential for tail formation. By using different bacterial mutants, it was also shown that not only the RkpM and RkpY proteins but also the RkpZ protein of the host takes part in the formation of the phage receptor. Results for the host range phage mutants and the receptor mutant bacteria suggest that the HII tail protein interacts with the capsular polysaccharide of the host and that the tail protein encoded by the original h gene recognizes a proteinaceous receptor.The Sinorhizobium meliloti-Medicago symbiosis is an important model for endosymbiotic nitrogen fixation. The genome sequence of S. meliloti (strain 1021) has been established (14), and the Medicago truncatula genome is under intensive investigation (3). Phage 16-3 is a temperate, double-stranded DNA phage of S. meliloti strain 41. It is by far the best-studied rhizobiophage and serves as a tool in analyses of rhizobium genetics, in the isolation of some symbiotic mutants, and in the construction of special vectors. Genetic determinants and molecular mechanisms of many aspects of the 16-3 life cycle, such as phage integration and excision (8, 26, 38), regulation of the lytic/lysogenic switch (5, 6, 9, 24, 28), immunity to superinfection (4), phage DNA packaging (15), and the role of gene h in the host range (32), have been examined in detail. Moreover, the complete 60-kb phage genome sequence (accession no. {"type":"entrez-nucleotide","attrs":{"text":"DQ500118","term_id":"111054886","term_text":"DQ500118"}}DQ500118) has been determined recently (P. P. Papp et al., unpublished results). However, little is known about the genes and structural elements involved in the interaction between the phage and its host, and furthermore, only one study of the 16-3 virion proteins has been reported (11).The initial interaction between a tailed phage and its bacterial host cell is mediated by the distal part of the phage tail, which specifically binds to the phage receptor located on the host surface. Earlier results demonstrated that phage 16-3 adsorption is connected to the strain-specific capsular polysaccharide of S. meliloti 41, the K_R5 antigen. So far, three bacterial gene clusters involved in K_R5 antigen production, including the rkp-1, rkp-2, and rkp-3 regions, have been described. rkp mutants are defective in the invasion of the host plant for symbiosis. In addition, they cannot adsorb phage 16-3, suggesting that the K_R5 antigen is required for both functions (19, 20, 30).In order to elucidate the molecular mechanism of phage 16-3 and S. meliloti 41 recognition, bacterial mutants carrying an altered phage receptor and host range phage mutants able to overcome the adsorption block have been characterized previously (32). It was shown that the RkpM protein, together with other yet uncharacterized elements, is a component of the phage receptor. With the use of rkpM mutants, host range mutations in phage gene h, which probably encodes the tail fiber protein, were identified. Interestingly, some mutations influencing phage-host recognition could not be localized in the rkpM and h genes, indicating that on both sides, additional components are important for bacteriophage-host recognition.The aim of this study was to identify additional genetic determinants involved in S. meliloti 41 and phage 16-3 recognition by characterizing new host range and receptor mutants. Furthermore, by using insertional mutagenesis, we examined a region of the phage chromosome supposed to be responsible for tail formation and identified six new genes essential for phage assembly.     

High-fat diet-induced reduction in nitric oxide-dependent arteriolar dilation in rats: role of xanthine oxidase-derived superoxide anion

Obesity frequently leads to the development of hypertension. We hypothesized that high-fat diet (HFD)-induced obesity impairs the endothelium-dependent dilation of arterioles. Male Wistar rats were fed with normal (control) or HFD (60% of saturated fat, for 10 wk). In rats with HFD, body weight, mean arterial blood pressure, and serum insulin, cholesterol, and glucose were elevated. In isolated gracilis muscle arterioles (diameter: approximately 160 microm) of HFD, rat dilations to ACh (at 1 microM, maximum: 83 +/- 3%) and histamine (at 10 microM, maximum: 16 +/- 4%) were significantly (P < 0.05) decreased compared with those of control responses (maximum: 90 +/- 2 and 46 +/- 4%, respectively). Dilations to the NO donor sodium nitroprusside were similar in the two groups. Inhibition of NO synthesis by N(omega)-nitro-l-arginine methyl ester reduced ACh- and histamine-induced dilations in control arterioles but had no effect on microvessels of HFD rats. The superoxide dismutase mimetic Tiron or xanthine oxidase inhibitor allopurinol enhanced ACh (maximum: 90 +/- 2 and 93 +/- 2%, respectively)- and histamine (maximum: 30 +/- 7 and 37 +/- 8%, respectively)-induced dilations in HFD arterioles, whereas the NAD(P)H oxidase inhibitor apocynin had no significant effect. Correspondingly, in carotid arteries of HFD rats, an enhanced superoxide production was shown by lucigenin-enhanced chemiluminescence, in association with an increased xanthine oxidase, but not NAD(P)H oxidase activity. In addition, a marked xanthine oxidase immunostaining was detected in the endothelial layer of the gracilis arterioles of HFD, but not in control rats. These findings suggest that, in obese rats, NO mediation of endothelium-dependent dilation of skeletal muscle arterioles is reduced because of an enhanced xanthine oxidase-derived superoxide production. These alterations demonstrate substantial dysregulation of arteriolar tone by the endothelium in HFD-induced obesity, which may contribute to disturbed tissue blood flow and development of increased peripheral resistance.     

Competition between Transposable Elements and Mutator Genes in Bacteria

Although both genotypes with elevated mutation rate (mutators) and mobilization of insertion sequence (IS) elements have substantial impact on genome diversification, their potential interactions are unknown. Moreover, the evolutionary forces driving gradual accumulation of these elements are unclear: Do these elements spread in an initially transposon-free bacterial genome as they enable rapid adaptive evolution? To address these issues, we inserted an active IS1 element into a reduced Escherichia coli genome devoid of all other mobile DNA. Evolutionary laboratory experiments revealed that IS elements increase mutational supply and occasionally generate variants with especially large phenotypic effects. However, their impact on adaptive evolution is small compared with mismatch repair mutator alleles, and hence, the latter impede the spread of IS-carrying strains. Given their ubiquity in natural populations, such mutator alleles could limit early phase of IS element evolution in a new bacterial host. More generally, our work demonstrates the existence of an evolutionary conflict between mutation-promoting mechanisms.     

Repayment Flexibility Can Reduce Financial Stress: A Randomized Control Trial with Microfinance Clients in India

Financial stress is widely believed to cause health problems. However, policies seeking to relieve financial stress by limiting debt levels of poor households may directly worsen their economic well-being. We evaluate an alternative policy – increasing the repayment flexibility of debt contracts. A field experiment randomly assigned microfinance clients to a monthly or a traditional weekly installment schedule (N = 200). We used cell phones to gather survey data on income, expenditure, and financial stress every 48 hours over seven weeks. Clients repaying monthly were 51 percent less likely to report feeling “worried, tense, or anxious” about repaying, were 54 percent more likely to report feeling confident about repaying, and reported spending less time thinking about their loan compared to weekly clients. Monthly clients also reported higher business investment and income, suggesting that the flexibility encouraged them to invest their loans more profitably, which ultimately reduced financial stress.