Defending the genome from the enemy within:mechanisms of retrotransposon suppression in the mouse germline

The viability of any species requires that the genome is kept stable as it is transmitted from generation to generation by the germ cells. One of the challenges to transgenerational genome stability is the potential mutagenic activity of transposable genetic elements, particularly retrotransposons. There are many different types of retrotransposon in mammalian genomes, and these target different points in germline development to amplify and integrate into new genomic locations. Germ cells, and their pluripotent developmental precursors, have evolved a variety of genome defence mechanisms that suppress retrotransposon activity and maintain genome stability across the generations. Here, we review recent advances in understanding how retrotransposon activity is suppressed in the mammalian germline, how genes involved in germline genome defence mechanisms are regulated, and the consequences of mutating these genome defence genes for the developing germline

Thermodynamic investigation of the azeotropic system - The binary system of (water plus cyclohexane)

The molar heat capacities of the azeotropic system (0.30 mol water + 0.70 mol cyclohexane) were measured by an adiabatic calorimeter in temperature range of 78-320 K. The functions of the heat capacity with respect to thermodynamic temperature were established. The phase transition took place in temperature ranges of 184-190, 271-276 and 276-283 K corresponding to the solid-solid phase transition of cyclohexane, solid-liquid phase transition of water and solid-liquid phase transition of cyclohexane, respectively. The corresponding enthalpies and entropies of the phase transition were found to be 4.559 kj mol(-1), 24.510 +/- 0.065 J K-1 mol(-1); 2.576 kj mol(-1), 9.454 +/- 0.041 J K-1 mol(-1); and 2.040 kj mol(-1), 7.296 +/- 0.029 J K-1 mol(-1), respectively. The thermodynamic functions and the excess thermodynamic functions of the azeotrope were derived based on the relationships of the thermodynamic functions. (C) 2003 Elsevier B.V. All rights reserved

Calorimetric study and thermal analysis of [Ho-2(Ala)(4)(H2O)(8)]Cl-6 and [ErY(Ala)(4)(H2O)(8)] (ClO4)(6)

Two solid complexes of rare-earth compounds with alanine, [HO2(Ala)(4)(H2O)(8)] Cl-6 and [ErY(Ala)(4)(H2O)(8)] (ClO4)(6) (Ala = alanine) were synthesized, and a calorimetric study and thermal analysis for the two complexes were performed through adiabatic calorimetry and thermogravimetry. The low-temperature heat capacities of [HO2(Ala)(4)(H2O)(8)] Cl-6 and [ErY(Ala)(4)(H2O)(8)] (ClO4)(6) were measured with an automated adiabatic precision calorimeter over the temperature range from 78 to 377 K. Solid-solid phase transitions were found between 214 K and 255 K with a peak temperature of 235.09 K for [HO2(Ala)(4)(H2O)(8)] Cl-6, between 99 K and 121 K with a peak temperature of 115. 78 K for [ErY (Ala)(4) (H2O)(8)] (ClO4)(6). The enthalpies and entropies of the phase transitions were determined to be 3.02 kJ . mol(-1), 12.83 J . K-1 . mol(-1) for [HO2(Ala)(4)(H2O)(8)] Cl-6; 1.96 kJ . mol(-1), 16.90 J . K-1 . mol(-1) for [ErY(Ala)(4)(H2O)(8)] (ClO4)(6), respectively. Thermal decomposition of the two complexes were investigated in the temperature range of 40 similar to 800 degreesC by using the thermogravimetric and differential thermogravimetric (TG/DTG) analysis techniques. The TG/DTG curves showed that the decomposition started from 80 degreesC and ended at 479 degreesC, completed in two steps for [HO2 (Ala)(4) (H2O)(8)]Cl-6, and started from 120 degreesC and ended at 430 degreesC, completed in three steps for [ErY(Ala)(4) (H2O)(8)] (ClO4)(6), respectively. The possible mechanisms of the thermal decompositions were elucidated

Low-temperature heat capacity and thermal decomposition of crystalline [Er-2(His center dot H+)(H2O)8](ClO4)(6)center dot 4H(2)O

The heat capacities of rare earth complex with amino acid histidine, [Er-2(His.H+)(H2O)(8)](ClO4)(6).4H(2)O, were measured with an automatic adiabatic calorimeter from 79 to 320 K. It was found that there was a sudden increment in heat capacity within the temperature range 182-190 K. Thermal decomposition behavior of the complex in nitrogen atmosphere was studied by thermogravimetric (TG) analysis, and a possible decomposition mechanism was suggested according to TG-DTG results. (C) 2003 Elsevier B.V. All rights reserved

Mesophilic-hydrothermal-thermophilic (M-H-T) digestion of green corn straw

Mesophilic-hydrothermal (80-160 degrees C, 30 min)-thermophilic (M-H-T) digestion and control tests of mesophilic (M), thermophilic (T), hydrothermal-mesophilic (H-M), and mesophilic-thermophilic digestion (M-T) of green corn straw were conducted for a 20-day fermentation period. The results indicate that M-H-T is an efficient method to improve methane production. A maximum methane yield of 371.74 mL/g volatile solid was obtained by the M (3 days)-H (140 degrees C)-T (17 days) process, which was 20.44%, 16.55%, 31.44%, and 14.31% higher than the yields of the M, T, 140-M, and M-T processes. The enhanced methane production was attributed to (1) the improved hemicellulose degradation and lignin disorganization; (2) prevention of the degradation of soluble sugar, easily hydrolyzed hemicellulose and cellulose into furfural and methylfurfural; and (3) lack of formation of Maillard reaction products during initial hydrothermal treatment. (C) 2015 Elsevier Ltd. All rights reserved

Kinetics of methane production and hydrolysis in anaerobic digestion of corn stover

In order to develop a time-saving method for determination of ultimate methane production, obtain the hydrolysis kinetic constant, and identify a determination method for the nonbiodegradable organic fraction of substrate (VSNB) of green and air-dried corn stover, the kinetics of methane production and hydrolysis were studied using batch tests. The results showed that the conventional first-order hydrolysis kinetic model was not suitable for describing the entire hydrolysis process of corn stover, because there were two first-order decay periods for hydrolysis of corn stover. The hydrolysis kinetic constants k(H,1) and kH,2 of the first and second periods were 0.1701 and 0.04151/d for green stover and 0.1052 and 0.03601/d for air-dried stover. The value of VSNB could be obtained by the graphical method rather than by the hydrolysis kinetic model. The obtained VSNB contents were 12.9% and 24.7% of VS (volatile solid) for green and air-dried stover, respectively. The ultimate methane production and corresponding digestion time could be understood through the methane production kinetic model by digestion experiments within a short time. The ultimate methane productions were 347.1 and 319.4 mL/g based on VS and the corresponding digestion times were 69.2 and 1823 days for green and air-dried stover, respectively. (C) 2016 Elsevier Ltd. All rights reserved