Soil microbial distribution and assembly are related to vegetation biomass in the alpine permafrost regions of the Qinghai-Tibet Plateau.

It is generally believed that there is a vegetation succession sequence from alpine marsh meadow to desert in the alpine ecosystem of the Qinghai-Tibet Plateau. However, we still have a limited understanding about distribution patterns and community assemblies of microorganisms' response to such vegetation changes. Hence, across a gradient represented by three types of alpine vegetation from swamp meadow to meadow to steppe, the soil bacterial, fungal and archaeal diversity was evaluated and then associated with their assembly processes, and glacier foreland vegetation was also surveyed as a case out of this gradient. Vegetation biomass was found to decrease significantly along the vegetation gradient. In contrast to irregular shifts in alpha diversity, bacterial and fungal beta diversities that were dominated by species replacement components (71.07-79.08%) significantly increased with the decreasing gradient in vegetation biomass (P < 0.05). These trends of increase were also found in the extent of stochastic bacterial and fungal assembly. Moreover, an increase in microbial beta diversity but a decrease in beta nearest taxon index were observed along with increased discrepancy in vegetation biomass (P < 0.001). Stepwise regression analyses and structural equation models suggested that vegetation biomass was the major variable that was related to microbial distribution and community assembly, and there might be associations between the dominance of species replacements and stochastic assembly. These findings enhanced our recognition of the relationship between vegetation and soil microorganisms and would facilitate the development of vegetation-microbe feedback models in alpine ecosystems.

[Expression of nuclear factor-kappaB in bone marrow cells from patients with acute leukemia and its relationship with P21, MMP-2 and MMP-9].

To investigate the expression of NF-kappaB in acute leukemia and its relationship with P21, and matrix metalloproteinases (MMP), the expression of NF-kappaB, P21, MMP-2 and MMP-9 in bone marrow cells from patients with acute leukemia (AL) was detected using immunocytochemical technique. The results showed that the expression ratios of NF-kappaB, P21, MMP-2 and MMP-9 in untreated AL group were significantly higher than those in remission and normal control groups (P < 0.05), and no obvious difference was seen between remission and normal control groups. The expression of NF-kappaB was correlated with that of P21, MMP-2 and MMP-9 (r = 0.767, 0.729 and 0.803, respectively, P < 0.05). This study indicated that P21 protein, encoded by oncogene Ras, and NF-kappaB were super-expressed in leukemia cells. In conclusion, after activation by Ras, NF-kappaB combined with the kappaB sequences of MMP-2 and MMP-9 genes, then upregulated their expression. MMP might enhance the degradative function of leukemic cell, thus to make cells easier to cross through the bone marrow barrier and release into blood.