How to make a minimal genome for synthetic minimal cell

As a key focus of synthetic biology, building a minimal artificial cell has given rise to many discussions. A synthetic minimal cell will provide an appropriate chassis to integrate functional synthetic parts, devices and systems with functions that cannot generally be found in nature. The design and construction of a functional minimal genome is a key step while building such a cell/chassis since all the cell functions can be traced back to the genome. Kinds of approaches, based on bioinformatics and molecular biology, have been developed and proceeded to derive essential genes and minimal gene sets for the synthetic minimal genome. Experiments about streamlining genomes of model bacteria revealed genome reduction led to unanticipated beneficial properties, such as high electroporation efficiency and accurate propagation of recombinant genes and plasmids that were unstable in other strains. Recent achievements in chemical synthesis technology for large DNA segments together with the rapid development of the whole-genome sequencing, have transferred synthesis of genes to assembly of the whole genomes based on oligonucleotides, and thus created strong preconditions for synthesis of artificial minimal genome. Here in this article, we review briefly the history and current state of research in this field and summarize the main methods for making a minimal genome. We also discuss the impacts of minimized genome on metabolism and regulation of artificial cell.

[Prognostic significance of natural killer cell infiltration in hepatocellular carcinoma].

BACKGROUND AND OBJECTIVE: Several studies have Shown the correlation of high numbers of tumor-infiltrating natural killer (NK) cells with a good prognosis for cancer patients. This study was to investigate the impact of NK cell infiltration on the survival and prognosis of patients with hepatocellular carcinoma (HCC) after resection. METHODS: The proportion of infiltrating NK cells of HCC patients was measured using flow cytometry, and the expression of CD56+ (NK) cells was investigated using immunohistochemistry. Prognostic values of intratumoral and peritumoral NK cell densities were evaluated by Kaplan-Meier method and Cox regression. RESULTS: The level of NK cells was significantly lower in tumor-infiltrating lymphocytes (TIL) of HCC patients than in nontumor-infiltrating lymphocytes (NIL) [(11.8 +/- 8.1)% vs. (18.0+/-7.9)%, P=0.002]. The density of NK cells was also significantly lower in cancer nests than in peritumoral lesions (2.3 +/- 2.6 vs. 8.5 +/- 4.5 cells per field, P<0.001). Patients with low intratumoral NK cells had shorter disease-free survival (P=0.027) and overall survival (P=0.005) than patients with high intratumoral NK cells. In contrast, NK cells in the peritumoral area showed no prognostic significance for either disease-free survival or overall survival. Multivariate Cox proportional hazards analysis showed that intratumoral NK cell density was an independent prognostic factor of prolonged overall survival (hazard ratio = 2.658, P=0.019). CONCLUSION: Low NK cells infiltration could predict poor prognosis in patients with HCC.

Effects between the first-and second-generation histamine H1-antagonists on seizure development of pentylenetetrazole-induced kindling in rats / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the effects and the mechanisms of the first-generation histamine H(1)-antagonist diphenhydramine and the second-generation histamine H(1)- antagonist fexofenadine on seizure development of pentylenetetrazole (PTZ)-induced kindling in rats.</p><p><b>METHODS</b>The first-or second-generation histamine H(1)-antagonists and/or histidine were ip injected in rats every 48 h, followed by a subconvulsive dose of PTZ (35 mg/kg). Then the behavioral changes were observed for 30 min after every injection of PTZ. The histamine content of brain was measured spectrofluorometrically.</p><p><b>RESULT</b>Compared with the control group, diphenhydramine (5 mg/kg) significantly augmented the severity of seizure development of PTZ-induced kindling, whereas fexofenadine (5 mg/kg) had no marked influence. The effects of diphenhydramine were antagonized by histidine, the precursor of histamine.</p><p><b>CONCLUSION</b>Seizure development of PTZ-induced kindling is promoted by the first-but not the second generation histamine H(1)-antagonists via the blockade of brain histamine H(1)-receptor.</p>