Effect of sucrose on cryopreservation of pig spermatogonial stem cells

Sucrose is known to play an important role in the cryopreservation of sperm and female gonads; however, its effect on the cryopreservation ofpig spermatogonial stem cells （pSSCs） has not been tested. The aim of this work was to study the effect of sucrose during pSSC cryopreservation and to find the most effective concentration in freezing medium, pSSCs were cryopreserved with freezing media containing different concentrations of sucrose （70, 140, 210, and 280 mmol L^-1） and a control group without sucrose. The survival rates, plasma membrane integrity, and mitochondrial membrane potential of thawed cells were detected by trypan blue （TB） staining, SYBR-14/propidium iodide （PI） dual staining, and JC-1 staining, respectively. All the staining results showed an obvious increase in cell survival in the sucrose-treated groups as compared to that in the control group, with the exception of 280 mmol L^-1 sucrose. Moreover, the 210 mmol L^-1 sucrose group yielded the highest survival rate among all the groups （P〈0.05）. The results of SYBR-14/PI dual staining and JC-1 staining were consistent with those of TB staining as above described. Quantitative real-time PCR （qRT-PCR） indicated that the mRNA levels of three apoptosis-promoting genes （BAX, APAF1 and CASPASE9） were significantly higher in thawed cells than in cells before freezing （P〈0.05）. Moreover, the mRNA level of one anti-apoptotic gene （XIAP） was significantly lower in thawed cells than in cells before freezing （P〈0.05）. When comparing the mRNA expression of apoptosis-related genes in thawed cells, the mRNA level of the anti-apoptotic genes in the control group was significantly lower than that in the sucrose-treated groups （P〈0.05）. Western blot analyses showed that the expression levels of cleaved CASPASE9, CASPASE3 and PARP-1 in the sucrose-treated groups were lower than those in the control group and were the lowest in the 210 mmol L-1 sucrose group. Both qRT-PCR and Western blot analyses suggested that sucrose inhibited cell apoptosis during freezing and thawing. Briefly, sucrose promoted pSSCs survival after freezing and thawing, especially at a concentration of 210 mmol L^-1, which possibly assisted pSSC dehydration and inhibited cell apoptosis. These findings hold great promise for further studies of the regulatory mechanism of proliferation and differentiation of pSSCs.

Correlation of Gluten Molecular Conformation with Dough Viscoelastic Properties during Storage

Significant correlations exist for the total sample between the dough viscoelastic properties and quality, but little information about these links is available. This study investigates the relationship between the gluten molecular conformation and the dough viscoelastic properties of the Zhengmai 379 wheat variety with different relative humidity(RH) values during storage.The results showed that protein extractability, free sulfhydryl(SH) groups, and wet gluten contents decreased to a certain degree during storage, while the glutenin quantity significantly varied. Significant negative correlation coefficients were found between the dough viscosity at 50% RH and the β-turn contents at 40% RH(-0.918) or 60% RH(-0.949)(P < 0.01), the dough viscosity at50% RH and the β-turn contents at 50% RH(-0.912)(P < 0.05), and the dough viscosity at 50% RH and the α-helix/β-sheet ratio at 40% RH(-0.875), 50% RH(-0.869), or 60% RH(-0.843)(P < 0.05). Significant correlation coefficients were further observed between the dough viscosity at 50% RH and the β-sheet contents at 60% RH(0.927)(P < 0.01) and between the dough viscosity at50% RH and the β-sheet contents at 40% RH(0.910) or 50% RH(0.908)(P < 0.05). A decrease in the free SH groups of gluten and an increase in the low-molecular weight contents suggested that gliadin was incorporated via SS crosslinking to the glutenin-like protein, which did not dissolve in ethanol.

Inferences in Linear Mixed Models with Skew-normal Random Effects

For the linear mixed model with skew-normal random effects, this paper gives the density function, moment generating function and independence conditions. The noncentral skew chi-square distribution is defined and its density function is shown. The necessary and sufficient conditions under which a quadratic form is distributed as noncentral skew chi-square distribution are obtained. Also, a version of Cochran＇s theorem is given~ which modifies the result of Wang et al. （2009） and is used to set up exact tests for fixed effects and variance components of the proposed model. For illustration, our main results are applied to a real data problem.