Etude comparee des proprietes physico-chimiques des mannanes de neuf levures

In order to correlate and compare the antigenic relationships observed between nine yeast strains, we have studied their major antigenic determinant represented by the mannans. This material is a constituent of their cell.The compounds that we have isolated are, in reality, glycopeptides. All their polysaccharide fractions consist of mannose only — except for those of the compounds that we have isolated of R. glutinis and C. lipolytica. All these polysaccharides have very close ramified structures; the only one that seems to be very different is that of R. glutinis, and this is in agreement with the antigenic properties of that yeast.The peptidic fractions of these glycopeptides are rich in threonine, serine and aspartic acid and it is very likely that these amino acids make the link with the polysaccharide fraction. The quantity of these amino acids seem to be affected by the conditions of culture of the yeasts, but not their presence or absence.     

The genetics of cell-mediated lympholysis.

The role of HLA antigens in the generation of cytotoxic cells in CML has been investigated. Cytotoxic effector cells were generated in MLC among HLA-A or HLA-A and HLA-B disparate, HLA-D identical siblings, and among HLA-A and HLA-B disparate, MLC identical (%RR less than or equal to 2 3.6) unrelated individual. The data indicate that HLA-D differences and poliferative MLC responses as measured by 3H-thymidine incorporation are not requisite for the in vitro generation of cytotoxic cells and suggest the existence of a CML-S locus (loci) distinct from HLA-A, HLA-B and HLA-D. The degree of cytotoxicity generated in a proliferative versus a "nonproliferative" MLC was comparable. In addition, these studies demonstrate that antigens other than the currently definable HLA-A, HLA-B, HLA-C, and HLA-D can serve as target determinants in cell-mediated lympholysis.     

Levans. II. Light-scattering and sedimentation data of Streptococcus salivarius Levan in water.

The molecular weights and radii of gyration of Streptococcus salivarius levan fractions were obtained from light-scattering measurements in water. Sedimentation coefficients and partial specific volumes of the fractions were also obtained. Double logarithmic plots of [η] versus M?_w and S⁰ versus M?_w yielded slopes having values of 0.17 and 0.62, respectively. The data and various calculated parameters show that levan from Streptococcus salivarius is highly branched and behaves hydrodynamically as a compact particle of spherical symmetry.     

A human-mouse somatic hybrid line selected for human deoxycytidine deaminase.

A new selective medium has been developed for cells containing the enzyme deoxycytidine deaminase. This medium contains hypoxanthine, aminopterin, and 5-methyldeoxycytidine (HAM medium). To survive in the presence of the aminopterin, the cells must utilize deoxycytidine deaminase to convert the 5-methyldeoxycytidine to thymidine. The cells must also have thymidine kinase and hypoxanthine phosphoribosyltransferase. A mouse cell line deficient in deoxycytidine deaminase has been isolated from a deoxycytidine kinase-deficient line, using 5-bromodeoxycytidine as the selective agent. A hybrid line between this double mutant and a human diploid fibroblast was isolated in HAM medium. The hybrid line contains the chromosomes expected of a human-mouse hybrid. The deoxycytidine deaminase isozyme patterns on cellogel show that the human-mouse hybrid cell line produces an enzyme with an electrophoretic mobility intermediate between that of the human and that of the mouse.     

基于MaxEnt模型的甘肃安西极旱荒漠国家级自然保护区北山羊生境评估

明晰甘肃安西极旱荒漠国家级自然保护区珍稀濒危物种北山羊的分布格局,并阐释气候变化和人类活动对北山羊的影响,对今后北山羊生境管理和物种保护具有重要意义。基于北山羊实测分布点记录和环境变量数据,结合MaxEnt模型和ArcGIS空间分析功能,利用CMIP6的8个气候模式均值预测中度发展路径（SSP2-4.5）下,基准期（1970-2000年）和未来气候（2041-2060年、2081-2100年）变化情景下,甘肃安西极旱荒漠国家级自然保护区北山羊的潜在适生区分布范围及变化,并综合贡献率和置换重要性值对北山羊生境选择关键环境因子进行了分析。研究结果表明：（1） MaxEnt模型的预测精度较高,三种气候条件下ROC曲线下面积（AUC,Area Under Curve）>0.97,且真实技巧统计（TSS,True Skill Statistic）>0.90,模拟结果可靠。（2）影响北山羊生境选择的主要环境因子为气候条件（降水量季节性变异系数和等温性）、海拔和人为干扰（距泉和居名点距离）。水是保护区北山羊生存的最基本要素,气候条件共同控制北山羊生境条件。此外,北山羊习性决定其生境宜选择高海拔和远离人类活动影响地区。（3）基准期保护区北山羊主要分布在北片和南片高海拔山区,面积365.77 km²（占整个保护区的4.31%）,北山羊适生区面积北片>南片、中高等适生区主要位于保护区北片。（4） CMIP6未来气候变化情景下,随着保护区生态环境改善和濒危物种保护措施的实施,北山羊潜在适生区面积呈增加趋势,但是受北山羊近亲繁殖的影响,整体上北山羊数量和适生区面积增加并不显著且有向南部及高海拔地区转移趋势。     

Strong plastid degradation is consistent within section Chondrophyllae,the most speciose lineage of Gentiana

Recovering phylogenetic relationships in lineages experiencing intense diversification has always been a persistent challenge in evolutionary studies, including in Gentiana section Chondrophyllae sensu lato (s.l.). Indeed, this subcosmopolitan taxon encompasses more than 180 mostly annual species distributed around the world. We sequenced and assembled 22 new plastomes representing 21 species in section Chondrophyllae s.l. In addition to previously released plastome data, our study includes all main lineages within the section. We reconstructed their phylogenetic relationships based on protein‐coding genes and recombinant DNA (rDNA) cistron sequences, and then investigated plastome structural evolution as well as divergence time. Despite an admittedly humble species cover overall, we recovered a well‐supported phylogenetic tree based on plastome data, and found significant discordance between phylogenetic relationships and taxonomic treatments. Our results show that G. capitata and G. leucomelaena diverged early within the section, which is then further divided into two clades. The divergence time estimation showed that section Chondrophyllae s.l. evolved in the second half of the Oligocene. We found that section Chondrophyllae s.l. had the smallest average plastome size (128 KB) in tribe Gentianeae (Gentianaceae), with frequent gene and sequence losses such as the ndh complex and its flanking regions. In addition, we detected both expansion and contraction of the inverted repeat (IR) regions. Our study suggests that plastome degradation parallels the diversification of this group, and illustrates the strong discordance between phylogenetic relationships and taxonomic treatments, which now need to be carefully revised.     

灰葡萄孢侵染垫缺失突变体的筛选及其相关生物学特性的研究

【目的】从农杆菌介导获得的灰葡萄孢RoseBC-3的突变体库中筛选侵染垫缺失突变体菌株,并明确其相关生物学特性。【方法】将菌株接种于洋葱表皮,利用棉兰染色观察侵染垫形成情况,筛选得到一个侵染垫缺失突变体(AT19)。采用形态学方法、离体叶片接种法、钌红染色法、小麦种子幼芽生长抑制法分别对该菌株的菌落培养性状、侵染垫产生情况、致病力、产果胶酶能力以及产植物毒性代谢产物能力进行测定。【结果】筛选灰葡萄孢突变体168株,根据侵染垫形成可分为三类：快速形成侵染垫型(158株)、缓慢形成侵染垫型(9株)和侵染垫形成缺陷型(1株,AT19)。AT19在接种洋葱120 h后依然无法形成成熟侵染垫。该菌株生长较为缓慢,菌落扩展均匀,可以产生分生孢子,对烟草、草莓、蚕豆和豌豆叶片均不能致病,可以产生果胶酶和植物代谢毒性物质。【结论】突变体菌株AT19可以产生果胶酶和植物代谢毒性物质,其致病力缺失与侵染垫产生缺陷相关。研究结果为了解灰葡萄孢侵染垫形成分子机制提供基础材料。     

植被格局对砒砂岩坡地降雨侵蚀的影响

为进一步研究砒砂岩区不同雨型下植被格局对坡面土壤侵蚀特征的影响,基于野外径流小区原位观测试验与景观生态学相结合的方法,通过对比分析不同坡面的植被斑块格局指数与产流产沙之间的相关关系,阐明植被格局对砒砂岩坡地降雨侵蚀的影响。结果表明:(1)该地区降雨可划分为3类,根据各植被坡面产流产沙能力,得出降雨侵蚀力表现为:雨型II(长历时、大雨量、大雨强) ＞ 雨型III(短历时、小雨量、中雨强) ＞ 雨型I(中历时、中雨量、小雨强)。降雨量和最大30min雨强与产流产沙量呈显著或极显著关系,相关系数0.695以上,是预测该区域水土流失的主要降雨因子。(2)各坡面水土保持能力与降雨类型有关,不同雨型下3种植被坡面减流减沙率分别达0.42%、20.8%以上,不同植被格局坡面减沙效益优于减流效益,3种植被坡面的减流能力为:雨型I ＞ 雨型III ＞ 雨型II。(3)3种植被坡面的径流泥沙模数由小到大依次为:均匀分布 ＜ 聚集分布 ＜ 随机分布,对比区域多年平均径流泥沙模数,3种植被坡面能够减少侵蚀达21.33%以上。(4)景观形状指数和分离度指数是影响坡面产流产沙的主要格局因子,相关系数分别达0.884和0.825以上。产流、产沙量与坡面植被斑块分离度呈显著正相关,与景观形状指数呈显著负相关。坡面产流量(Y₁)与斑块分离度(SPLIT)和景观形状指数(LSI)的关系式为Y₁=8.247SPLIT-6.605LSI+38.928,R²=0.905。以上结果表明植被斑块间的分离度越小,形状越复杂,坡面阻力增大,抗侵蚀能力越强。研究成果可为生态恢复过程中植被斑块格局的优化提供理论依据和数据支撑。     

Mutant C/EBPα p30 alleviates immunosuppression of CD8+ T cells by inhibiting autophagy‐associated secretion of IL‐1β in AML

ObjectivesMutant C/EBPα p30 (mp30), the product of C/EBPα double mutations (DM), lacks transactivation domain 1 and has C‐terminal loss‐of‐function mutation. Acute myeloid leukaemia (AML) patients harbouring C/EBPα DM could be classified as a distinct subgroup with favourable prognosis. However, the underlying mechanism remains elusive.Materials and MethodsAutophagy regulated by mp30 was detected by western blot and immunofluorescence. Immune infiltration analysis and GSEA were performed to investigate autophagic and inflammatory status of AML patients from the {"type":"entrez-geo","attrs":{"text":"GSE14468","term_id":"14468"}}GSE14468 cohort. Flow cytometry was applied to analyse T cell activation.ResultsMp30 inhibited autophagy by suppressing nucleus translocation of NF‐κB. Autophagy‐associated secretion of IL‐1β was decreased in mp30‐overexpressed AML cells. Bioinformatic analysis revealed that inflammatory status was attenuated, while CD8⁺ T cell infiltration was upregulated in C/EBPα DM AML patients. Consistently, the proportion of CD8⁺CD69⁺ T cells in peripheral blood mononuclear cells (PBMCs) was upregulated after co‐culture with mp30 AML cell conditional culture medium. Knock‐out of IL‐1β in AML cells also enhanced CD8⁺ T cell activation. Accordingly, IL‐1β expression was significantly reduced in the bone marrow (BM) cells of C/EBPα DM AML patients compared to the wildtype, while the CD8⁺CD69⁺ T cell proportion was specifically elevated.ConclusionsC/EBPα DM alleviates immunosuppression of CD8⁺ T cells by inhibiting the autophagy‐associated secretion of IL‐1β, which elucidated that repression of autophagy‐related inflammatory response in AML patients might achieve a favourable clinical benefit.

Mp30 suppresses autophagy‐associated IL‐β secretion, which ultimately alleviates the immunosuppression of CD8⁺ T cells in the microenvironment, contributing to favourable prognosis of AML patients.