Genetika a genomika hybridní sterility

Charles University in Prague Faculty of Science Ph.D. study program: Molecular and Cellular Biology, Genetics and Virology Abstract Genetics and genomics of hybrid sterility Mgr. Tanmoy Bhattacharyya Supervisor: Prof. MUDr. Jiří Forejt, DrSc. Praha 2013 Abstract Male-limited hybrid sterility restricts gene flow between the related species, an important pre- requisite of speciation. The F1 hybrid males of PWD/Ph female (Mus m. musculus subspecies) and C57BL/6J or B6 male (Mus m. domesticus) are azoospermic and sterile (PB6F1), while the hybrids from the reciprocal (B6PF1) cross are semi fertile. A disproportionately large effect of the X chromosome (Chr) on hybrid male sterility is a widespread phenomenon accompanying the origin of new species. In the present study, we mapped two phenotypically distinct hybrid sterility loci Hstx1 and Hstx2 to a common 4.7 Mb region on Chr. X. Analysis of meiotic prophase I of PB6F1 sterile males revealed meiotic block at mid-late pachynema and the TUNEL assay showed apoptosis of arrested spermatocytes. In sterile males over 95% of pachytene spermatocytes showed one or more unsynapsed autosomes visualized by anti SYCP1, HORMAD2 and SYCP3 antibodies. The phosphorylated form of H2AFX histone, normally restricted only to XY chromosome containing sex body decorated unsynapsed...Univerzita Karlova v Praze Přírodovědecká fakulta Doktorský studijní program: Molekulární a buněčná biologie, genetika a virologie Abstrakt Genetika a genomika hybridní sterility Mgr. Tanmoy Bhattacharyya Školitel: Prof. MUDr. Jiří Forejt, DrSc. Praha 2013 Abstrakt Samčí hybridní sterilita je překážkou v přenosu genů mezi příbuznými druhy, což je významným předpokladem pro vznik nových druhů. F1 hybridní samci vzniklí křížením samice PWD/Ph (poddruhu Mus m. musculus) a samce C57BL/6J nebo B6 (Mus m. domesticus) mají azoospermii a jsou sterilní (PB6F1), zatímco hybridi z recipročního (B6PF1) křížení jsou částečně fertilní. Nadměrně převládající vliv chromosomu (Chr) X na sterilitu samčích hybridů představuje jev, který je při vzniku nových druhů široce zastoupen. V této studii jsme mapovali dva fenotypově odlišné lokusy pro hybridní sterilitu Hstx1 a Hstx2 do společné oblasti o délce 4,7 Mb na Chr X. Analýza meiotické profáze I odhalila u sterilních samců PB6F1 meiotický blok ve střední fázi pozdního pachytenu a testem TUNEL byla prokázána apoptóza blokovaných spermatocytů. U sterilních samců byla v 95 % pachytenních spermatocytů vizualizací protilátkami anti SYCP1, HORMAD2 a SYCP3 zjistěna asynapse jednoho či více autosomů. Fosforylovaná forma histonu H2AFX, normálně pozorovaná pouze v pohlavním tělísku...Department of Genetics and MicrobiologyKatedra genetiky a mikrobiologieFaculty of SciencePřírodovědecká fakult

Probing the superconducting ground state of ZrIrSi: A μ\muSR study

The superconducting ground state of newly reported ZrIrSi is probed by means of $\mu$SR technique along with resistivity measurement. The occurrence of superconductivity at $T_\mathrm{C}$ = 1.7 K is confirmed by resistivity measurement. ZF-$\mu$SR study revealed that below $T_\mathrm{C}$, there is no spontaneous magnetic field in the superconducting state, indicates TRS is preserved in case of ZrIrSi. From TF-$\mu$SR measurement, we have estimated the superfluid density as a function of temperature, which is described by an isotropic $s-$wave model with a superconducting gap $2\Delta(0)/k_\mathrm{B}T_\mathrm{C}$ = 5.1, indicates the presence of strong spin-orbit coupling. {\it Ab-initio} electronic structure calculation indicates that there are four bands passing through the Fermi level, forming four Fermi surface pockets. We find that the low-energy bands are dominated by the $4d$-orbitals of transition metal Zr, with substantially lesser weight from the $5d$-orbitals of the Ir-atoms.Comment: 6 pages, 4 figure

Evidence of Nodal Line in the Superconducting Gap Symmetry of Noncentrosymmetric ThCoC2_{2}

The newly discovered noncentrosymmetric superconductor ThCoC$_{2}$ exhibits numerous unconventional behavior in the field dependent heat capacity data. Here we present the first measurement of the gap symmetry of ThCoC$_{2}$ by muon spin rotation/relaxation $(\mu$SR) measurements. Temperature dependence of the magnetic penetration depth measured using the transverse field $\mu$SR measurement reveal the evidence of nodal pairing symmetry. To understand these findings, we carry out the calculations of superconducting pairing eigenvalue and eigenfunction symmetry due to the spin-fluctuation mechanism, by directly implemented the {\it ab-initio} band structures. We find that the system possesses a single Fermi surface with considerable three-dimensionality, and hence a strong nesting along the $k_z$-direction. Such a nesting promotes a superconducting pairing with a $\cos{k_z}$-like symmetry with a prominent nodal line on the $k_z=\pm\pi/2$ plane. The result agrees well with the experimental data.Comment: 3 pages, 5 figure

Genetics and Genomics of Hybrid Sterility

Charles University in Prague Faculty of Science Ph.D. study program: Molecular and Cellular Biology, Genetics and Virology Abstract Genetics and genomics of hybrid sterility Mgr. Tanmoy Bhattacharyya Supervisor: Prof. MUDr. Jiří Forejt, DrSc. Praha 2013 Abstract Male-limited hybrid sterility restricts gene flow between the related species, an important pre- requisite of speciation. The F1 hybrid males of PWD/Ph female (Mus m. musculus subspecies) and C57BL/6J or B6 male (Mus m. domesticus) are azoospermic and sterile (PB6F1), while the hybrids from the reciprocal (B6PF1) cross are semi fertile. A disproportionately large effect of the X chromosome (Chr) on hybrid male sterility is a widespread phenomenon accompanying the origin of new species. In the present study, we mapped two phenotypically distinct hybrid sterility loci Hstx1 and Hstx2 to a common 4.7 Mb region on Chr. X. Analysis of meiotic prophase I of PB6F1 sterile males revealed meiotic block at mid-late pachynema and the TUNEL assay showed apoptosis of arrested spermatocytes. In sterile males over 95% of pachytene spermatocytes showed one or more unsynapsed autosomes visualized by anti SYCP1, HORMAD2 and SYCP3 antibodies. The phosphorylated form of H2AFX histone, normally restricted only to XY chromosome containing sex body decorated unsynapsed..

Heavy Metal Accumulation in Soil Amended with Roadside Pond Sediment and Uptake by Winter Wheat (Triticum aestivum L. cv. PBW 343)

The risks of heavy metal accumulation and the dynamics related to roadside pond sediment application in comparison to control of winter wheat (Triticum aestivum L.) were investigated in field experiments. Selective sequential extraction procedures revealed that application of pond sediment in soil increases the labile pools of the studied heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn). Risk assessment codes concluded that Cu and Pb were in the high-risk zone in both pond sediment and soil amended with pond sediment, whereas Zn and Cu were found in the medium-risk zone for control soil. Heavy metal accumulation by wheat straw and grain (39.38, 1.18, 23.73, 0.36, 0.18, and 16.8 mg kg-1 for Zn, Cd, Cu, Cr, Ni, and Pb, respectively, for wheat grain) was significantly increased through application of pond sediment. However, metal accumulation did not thwart the enhancement of wheat yield when pond sediment was applied. Health risk indexes of analyzed heavy metals were found to be within the Indian permissible limit for foodstuffs. Pond sediments help to fortify wheat grain by increasing the concentration of Zn and Cu as a source of micronutrients in the diet. However, a significant increase of Pb in wheat grain through pond sediment could be a health concern for its long-term application. Therefore, pond sediment would be a valuable resource for agriculture as an alternative organic supplement, but long-term use may require the cessation of the excavated sediment as agricultural landfill in order to restrict heavy metal contamination through it

Evaluation of Composts from Agricultural Wastes with Fish Pond Sediment as Bulking Agent to Improve Compost Quality

Composts with five different ratios of agricultural wastes, viz. rice straw (RS), wheat straw (WS), potato plant (PP), and mustard stover (MS) were prepared with or without fish pond bottom sediment to investigate the compost maturity and their suitability for field application. The composting process was monitored through the changes in physico‐chemical parameters and germination index (GI) at every 7 days interval of the composting process. All the composts were dark brown and smelled like forest soil within 56 days of composting, which reflected its matured status. On the basis of the physico‐chemical parameters (bulk density: 0.84 g/cm3; pH 7.05; electrical conductivity: 3.52 mS/cm; cation exchange capacity:82.4 cmol/kg; total carbon:321.4 g/kg; total nitrogen: 16.9 g/kg; As: 6.8 mg/kg; Cd: 2.96 mg/kg; Cr: 29.6 mg/kg, Cu: 243.6 mg/kg; Hg: 0.019 mg/kg; Ni: 24.3 mg/kg; Pb: 62.1 mg/kg and Zn: 812 mg/kg) and GI (89–96%), it could be concluded that RS/WS/PP/MS, 1:1:2:1 v/v/v/v with fish pond sediment produced better compost in accordance with the Indian compost standard. Application of a combined randomized block design analysis revealed that there is a significant difference in the responses of the five composts, in relation to the time of composting. Hierarchical clustering algorithm was applied with a view to form homogeneous groups of five different composts on the basis of different physico‐chemical parameters. Therefore, the ratio of waste incorporation is an important decision for composting and addition of pond sediment can improve the quality of compost

<i>Prdm9</i> Incompatibility Controls Oligospermia and Delayed Fertility but No Selfish Transmission in Mouse Intersubspecific Hybrids

<div><p>PR-domain 9 (<i>Prdm9</i>) is the first hybrid sterility gene identified in mammals. The incompatibility between <i>Prdm9</i> from <i>Mus musculus domesticus</i> (Mmd; the B6 strain) and the <i>Hstx2</i> region of chromosome (Chr) X from <i>M. m. musculus</i> (Mmm; the PWD strain) participates in the complete meiotic arrest of mouse intersubspecific (PWD×B6)F1 hybrid males. Other studies suggest that also semisterile intersubspecific hybrids are relevant for mouse speciation, but the genes responsible remain unknown. To investigate the causes of this semisterility, we analyzed the role of <i>Prdm9</i> and Chr X in hybrids resulting from the crosses of PWK, another Mmm-derived inbred strain. We demonstrate that <i>Prdm9</i> and Chr X control the partial meiotic arrest and reduced sperm count in (PWK×B6)F1 males. Asynapsis of heterosubspecific chromosomes and semisterility were partially suppressed by removal of the B6 allele of <i>Prdm9</i>. Polymorphisms between PWK and PWD on Chr X but not in the <i>Prdm9</i> region were responsible for the modification of the outcome of <i>Prdm9</i> - Chr X F1 hybrid incompatibility. Furthermore, (PWK×B6)F1 hybrid males displayed delayed fertility dependent on the <i>Prdm9</i> incompatibility. While the <i>Drosophila</i> hybrid sterility gene <i>Overdrive</i> causes both delayed fertility and increased transmission of its own chromosome to the offspring, the segregation of Chr X and the <i>Prdm9</i> region from the mouse (PWK×B6)F1 males was normal. Our results indicate extended functional consequences of <i>Prdm9</i> - Chr X intersubspecific incompatibility on the fertility of hybrids and should influence the design of fertility analyses in hybrid zones and of laboratory crosses between Mmm and Mmd strains.</p></div