Plant Response to Air Pollution,edited by M. Yunus and M. Iqbal

Water, Air, &; Soil Pollution -     

In Memoriam: Dr. John M. Laflen

The soil erosion research and soil and water conservation global community lost a treasured member on November 20, 2020, when Dr. John Matthew Laflen (Fig. 1) died. Always one with a friendly welcoming smile, John had hundreds of friends, both personally and professionally throughout the world. This article includes many of his professional and scientific contributions, and impacts from his research and outreach activities.     

Prof. James M. Tiedje Appointed as an Honorary Editor-in-Chief

<正>Prof. James M. Tiedje, University Distinguished Professor and Director of the Center for Microbial Ecology at Michigan State University, Academician of the American Academy of Sciences, has been appointed as an Honorary Editor-in-Chief of Pedosphere. Prof.     

甲基营养菌M.sp.MB200中serA基因功能初探

serA基因编码3-磷酸甘油酸脱氢酶（PGDH）,此酶在合成L-丝氨酸的第一步起催化作用。利用质粒pCM80分别与野生型基因serA、缺失了C末端ACT功能域的突变基因serA△77构建了重组体表达菌MB200/pCM80serA和MB200/pCM80serA△77。通过分析发现野生型基因重组表达菌的PGDH酶活受L-丝氨酸浓度影响较大,当反应体系中的L-丝氨酸浓度为40μmol/L时,酶活减少了约1/3;缺失了ACT功能域的基因表达菌的PGDH酶活基本不变,不受L-丝氨酸浓度的影响。进一步在静息细胞反应条件下,对重组菌和野生菌株MB200进行发酵产L-丝氨酸的研究,实验发现MB200/pCM80serA产L-丝氨酸的量为13.6mg/mL,MB200/pCM80serA△77产L-丝氨酸的量为16.8 mg/mL,而野生型菌株M.sp MB200的产量为6.4 mg/mL,重组菌的L-丝氨酸产量都有所提高,且MB200/pCM80serA△77的产量提高更多。结果证实了甲基营养菌MB200中serA基因与产L-丝氨酸具有反馈抑制关系,为进一步解除反馈抑制并发酵产L-丝氨酸奠定了基础。     

Sulfated glycosaminoglycans and collagen in two bovine muscles (M. Semitendinosus and M. Psoas major) differing in texture

M. semitendinosus (ST) and M. psoas major (PM) were used as models for tough and tender meat to study a possible role of sulfated glycosaminoglycans (GAGs) for muscle tenderness. The difference in texture was confirmed by Warner Bratzler shear force measurements. No significant difference in total amount of GAGs in the muscles was found. In contrast, a significant difference in the ratio of GAG/collagen was found between the two muscles. After separation of the GAGs by density gradient ultracentrifugation and ion-exchange chromatography, dermatan sulfate (DS), keratan sulfate (KS), chondroitin sulfate (CS), and heparan sulfate (HS) were identified by cellulose acetate electrophoresis after use of specific enzymes and chemical methods. The content of DS was higher in the tougher muscle (ST) than in PM, and the difference in DS content was statistically significant. Furthermore, a significant difference in the GAG composition pattern of the two muscles was found. The yield of GAGs extracted from the muscles was 77% for ST and 87% for PM. The residue after extraction was further analyzed and found to contain mainly HS. Immunohistochemical studies using antibodies against CS/DS showed a staining pattern of the perimysium of ST different from that of PM.     

M.T. Arts and B.C. Wainman: Lipids in Freshwater Ecosystems

Water, Air, &; Soil Pollution -     

小桐子SRAP-PCR体系优化与M1代变异植株的分子鉴定

首次利用SRAP分子标记手段对筛选出的18株经化学试剂、60Co γ辐射和低能离子注入等诱变处理后的小桐子变异植株进行遗传多样性分析。结果显示,22对SRAP引物一共扩增到266条带,其中54条为多态性条带,多态性比例为20.3%;18株形态变异的小桐子植株,大部分不仅在外部形态上发生了变异,而且在DNA水平上也发生了基因突变。这为今后利用诱变技术培育高产优质抗逆性强的小桐子新品种奠定了实践和理论基础。     

R.M. Harrison,R.E. van Grieken (eds.), Atmospheric Particles

Water, Air, &; Soil Pollution -