Thermal chip fabrication with arrays of sensors and heaters for micro-scale impingement cooling heat transfer analysis and measurements

The design and fabrication for a thermal chip with an array of temperature sensors and heaters for study of micro-jet impingement cooling heat transfer process are presented. This thermal chip can minimize the heat loss from the system to the ambient and provide a uniform heat flux along the wall, thus local heat transfer processes along the wall can be measured and obtained. The fabrication procedure presented can reach a chip yield of 100%, and every one of the sensors and heaters on the chip is in good condition. In addition, micro-jet impingement cooling experiments are performed to obtain the micro-scale local heat transfer Nusselt number along the wall. Flow visualization for the micro-impinging jet is also made. The experimental results indicate that both the micro-scale impinging jet flow structure and the heat transfer process along the wall is significantly different from the case of large-scale jet impingement cooling process.     

Phosphorylation of p70s6 kinase is implicated in androgen-induced levator ani muscle anabolism in castrated rats

Androgens are known to increase muscle mass, strength and muscle protein synthesis. However, the molecular mechanisms by which androgens regulate skeletal muscle development remain poorly understood. The ribosomal protein kinase p70^s6k is a regulator of ribosome biogenesis and plays an important role in the regulation of growth-related protein synthesis. The phosphorylation of p70^s6k has been implicated in load-induced skeletal muscle hypertrophy. In the current study, we determined the effect of DHT on the phosphorylation of p70^s6k in the androgen-sensitive levator ani muscle of castrated rats. DHT induced a rapid increase in the phosphorylation of p70^s6k, which was detectable within 6 h after a single injection. Interestingly, DHT-induced phosphorylation of p70^s6k occurred only in androgen-sensitive muscles, but not prostate and seminal vesicle. Co-administration of flutamide, an AR antagonist, inhibited DHT-induced p70^s6k phosphorylation. While serum IGF-I levels were not changed by DHT treatment, IGF-I gene expression levels increased and the mRNA levels of IGFBP3 and IGFBP5 were suppressed in the LA muscle after DHT replacement in castrated rats. These results suggest that the phosphorylation of p70^s6k, likely via the IGF-I pathway, may play an important role in androgen-induced skeletal muscle hypertrophy.     

Molecular characterization of the tobacco SET domain protein NtSET1 unravels its role in histone methylation, chromatin binding, and segregation

Plants contain a great number of genes encoding a distinctive class of SET domain proteins which harbor a plant-specific N-terminal part together with a C-terminal part showing highest sequence similarity to the catalytic domain of the yeast CLR4, the human SUV39H1 and G9a histone-methyltransferases (HMTases). Here we show that NtSET1, a representative member of this class from tobacco, methylated both K9 and K27 of histone H3 in vitro. Ectopic expression of NtSET1, by an inducible promoter, increased the amount of dimethylated H3K9 and induced chromosome-segregation defects in tobacco BY2 cells. Deletion analyses show that the HMTase activity, the association with specific chromatin regions and with condensed chromosomes, and the cellular effects largely depended on the C-terminal region including the SET domain of the protein. Nevertheless, the N-terminal part of NtSET1 was capable of targeting the green fluorescent protein to interphase chromatin. Finally, we show that NtSET1 bound LHP1, the Arabidopsis homolog of animal heterochromatin protein 1 (HP1), and that LHP1 co-localized with heterochromatin containing high amounts of dimethylated H3K9, suggesting a role for NtSET1 in heterochromatic function. Taken together, our results provide new insights into the molecular and global chromatin-binding activities of this particular class member of plant SET domain proteins.     

Infraciliature and myoneme system of Campanella umbellaria (Protozoa, Ciliophora, Peritrichida)

The infraciliature and myoneme system of Campanella umbellaria were revealed using the protargol impregnation technique. The main characteristics of the infraciliature are the peristomial ciliary rows (haplokinety and polykineties), which make four and a half turns around the peristomial disc before plunging into the infundibulum, and the aboral infraciliature, which is made up of the aboral ciliary wreath (trochal band) and the scopula. The myoneme system is composed of: 1) longitudinal fibers, which include 60-84 (mean 72.3) short longitudinal fibers, 40-56 (mean 45.8) medium-length longitudinal fibers, and numerous long longitudinal fibers; and 2) circular fibers, which include 8-12 (mean 9.3) peristomial ring fibers, linking fibers, support fibers, and peristomial disc fibers. The various fibers in C. umbellaria are interconnected to form a single myoneme system that may act as a cell skeleton as well as providing the mechanism by which the zooid contracts and relaxes.     

二氮嗪在长时程心脏低温保存中的作用

延长心脏的体外有效保存时间对临床心脏移植具有重要意义。本文旨在研究线粒体ATP敏感性钾通道开放剂二氮嗪(diazoxide,DE)在离体大鼠心脏长时程低温保存中的作用。SD大鼠随机分成5组,包括对照组(单纯Celsior保存液),DE组(Celsior液中含15、30或45μmol／L的DE)和DE 5-HD组[Celsior液中含30μmol／L的DE和100μmol／L的5-羟基葵酸盐(5-hydroxydecanoate,5-HD)]。利用Langendorff离体鼠心灌注法,观察心脏在4℃条件下保存10h后,复灌期血流动力学恢复、冠脉流出液中心肌酶漏出量及心肌水含量变化,并做心肌超微结构检查。结果显示：与对照组比较,DE处理后,复灌期的左心室舒张末期压力明显降低,心率、左心室发展压、左心室压力变化率、冠脉流出量等的恢复率在多个复灌时间点上优于对照组,且能显著减少复灌过程中心肌酶(乳酸脱氢酶、磷酸肌酸激酶及谷草转氨酶)的漏出量,降低心肌水含量;其中30和45μmol／LDE组的保护作用优于15μmol／LDE组;电镜结果显示DE对长时程低温保存心脏的超微结构有较好的保护作用。DE的上述作用可被线粒体ATP敏感性钾通道的特异性阻断剂5-HD所取消。以上结果提示：DE可通过激活线粒体ATP敏感性钾通道显著改善离体大鼠心脏长时程低温保存效果。     

Aluminum targets elongating cells by reducing cell wall extensibility in wheat roots

Phytotoxicity of aluminum is characterized by a rapid inhibition of root elongation at micromolar concentrations, however, the mechanisms primarily responsible for this response are not well understood. We investigated the effect of Al on the viscosity and elasticity parameters of root cell wall by a creep-extension analysis in two cultivars of wheat (Triticum aestivum L.) differing in Al resistance. The root elongation and both viscous and elastic extensibility of cell wall of the root apices were hardly affected by the exposure to 10 microM Al in an Al-resistant cultivar, Atlas 66. However, similar exposure rapidly inhibited root elongation in an Al-sensitive cultivar, Scout 66 and this was associated with a time-dependent accumulation of Al in the root tissues with more than 77% residing in the cell wall. Al caused a significant decrease in both the viscous and elastic extensibility of cell wall of the root apices of Scout 66. The "break load" of the root apex of Scout 66 was also decreased by Al. However, neither the viscosity nor elasticity of the cell wall was affected by in vitro Al treatment. Furthermore, pre-treatment of seedlings with Al in conditions where root elongation was slow (i.e. low temperature) did not affect the subsequent elongation of roots in a 0 Al treatment at room temperature. These results suggest that the Al-dependent changes in the cell wall viscosity and elasticity are involved in the inhibition of root growth. Furthermore, for Al to reduce cell wall extensibility it must interact with the cell walls of actively elongating cells.