Evidence that methylation of the FMR-I locus is responsible for variable phenotypic expression of the fragile X syndrome.

DNA at the FMR-1 locus was analyzed by Southern blot using probe StB12.3 in an unusual fragile X family with six brothers, three of whom are affected with fragile X to varying degrees, two of whom are nonpenetrant carriers, and one of whom is unaffected. Fragile X chromosome studies, detailed physical examinations, and psychological testing were completed on all six. Two of the affected brothers and the two nonpenetrant brothers were found to be methylation mosaics. The three affected males spanned the phenotypic and cognitive spectrum of the fragile X syndrome. A correlation was seen between the degree of methylation and the phenotypic expression identified in the three affected males. The two males initially classified as nonpenetrant were found to have mild phenotypic expression which consisted of minor cognitive deficits and a partial physical phenotype. These two, who were negative on fragile X chromosome studies, were found on DNA analysis to have large broad smears, with approximately 97% of the DNA unmethylated. The results described here indicate that some "nonpenetrant" carrier males may have varying amounts of methylation of the FMR-1 region, which can result in mild expression of the fragile X syndrome. The apparently mild phenotypic and cognitive expression of the fragile X syndrome in the two males, initially classified as nonpenetrant, who are mosaic for hypermethylation of an expansion of the CGG repeat in the premutation range, indicates that expression of the syndrome is not confined to males with large, hypermethylated expansions (full mutation) but has instead a gradient effect with a threshold for the full expression of the phenotype.     

在中国壮族家系中发现的一例-α~T/-α~Q复合β~0β~0珠蛋白基因型

本文报道在我国广西隆林壮族中发现一个罕見的HbQ复合α,β地中海贫血家系。先证者女,18岁,贫血面容,肝脾肿大。化学结构分析确证本Hb变异体为HbQ Thailand[α74(EF3)Asp→His]。血红蛋白组成以及α和β珠蛋白基因分析结果表明,先证者的珠蛋白基因型为-α~Q/-α~T复合β°/β°(IVSI-1G→T/Codon17A→T);先证者父的基因型为-‘α~Q/-复合β~O/β~A(IVSI-1G→T/β~A);先证母的基因型为-α~T/αα复合β~O/β~A(Codon17A→T/β~A)。     

盐酸胍诱导的α淀粉酶去折叠与再折叠

利用蛋白质内源荧光和酶活性两种信号以及荧光偏振,HPLC和停流等方法研究了盐酸胍诱导的α淀粉酶去折叠与重折叠的平衡转变和动力学。实验结果表明α淀粉酶去折叠与重折叠是两个不同的过程;变性与复性过程中可能伴有聚集体生成;去折叠与重折叠均为双相过程,重折叠大约始于2秒之后。     

黄花棘豆的喹诺里西定生物碱

豆科棘豆属有毒植物含多种有毒生物碱,有关棘豆属中生物碱成分的研究,早在1929年Couch由兰伯氏棘豆(Oxytropis lambertii DC.)中分离到一种多羟基化的含氮有机化合物,这是最早报道由棘豆属植物中分离出的生物碱成分,由于当时条件限制未能确定其结构。1982年美国农业部西部研究中心的植物化学家Molyneux从绢毛棘豆(Oxytropis sericea)中分离到苦马豆碱(swainsonine)等吲哚里西定生物碱(indolizidinealkaloids);1989年沈阳药学院于荣敏等由小花棘豆(Oxytropis glabra DC.)中分离出多种喹诺里西定生物碱。喹诺里西定生物碱具有多种生理活性,对试验动物中枢神经系统产生抑制,呼吸抑制或兴奋,致幻、流产和致畸等作用。本文报道由黄花棘豆(Oxytropis ochrocephala Bunge)中测得4种喹诺里西定生物碱。     

鼎湖山自然林豆科固氮植物资源的调查研究

本文在调查鼎湖山自然林木本豆科植物结瘤固氮的基础上,参阅了国内外有关豆科植物结瘤固氮的主要文献,研究了鼎湖山自然林木本豆科植物的固氮资源。结果得出鼎湖山自然林中常见的木本豆科植物共有41种,其中乔木15种,灌木6种,木质藤本20种;有结瘤固氮特性的26种,其中乔木11种,灌木5种,木质藤本10种;经初步调查未见根瘤的6种,其中乔木2种,灌木1种,木质藤本3种;未调查的9种,其中乔木2种,木质藤本7种。本研究结果为鼎湖山木本豆科固氮植物资源的保护、管理和开发利用提供了科学论据,在理论和应用方面均有重要意义。     

Role of pulmonary epithelial arginase-II in activation of fibroblasts and lung inflammaging

Elevated arginases including type-I (Arg-I) and type-II isoenzyme (Arg-II) are reported to play a role in aging, age-associated organ inflammaging, and fibrosis. A role of arginase in pulmonary aging and underlying mechanisms are not explored. Our present study shows increased Arg-II levels in aging lung of female mice, which is detected in bronchial ciliated epithelium, club cells, alveolar type 2 (AT2) pneumocytes, and fibroblasts (but not vascular endothelial and smooth muscle cells). Similar cellular localization of Arg-II is also observed in human lung biopsies. The age-associated increase in lung fibrosis and inflammatory cytokines, including IL-1β and TGF-β1 that are highly expressed in bronchial epithelium, AT2 cells, and fibroblasts, are ameliorated in arg-ii deficient (arg-ii^−/−) mice. The effects of arg-ii^−/− on lung inflammaging are weaker in male as compared to female animals. Conditioned medium (CM) from human Arg-II-positive bronchial and alveolar epithelial cells, but not that from arg-ii^−/− cells, activates fibroblasts to produce various cytokines including TGF-β1 and collagen, which is abolished by IL-1β receptor antagonist or TGF-β type I receptor blocker. Conversely, TGF-β1 or IL-1β also increases Arg-II expression. In the mouse models, we confirmed the age-associated increase in IL-1β and TGF-β1 in epithelial cells and activation of fibroblasts, which is inhibited in arg-ii^−/− mice. Taken together, our study demonstrates a critical role of epithelial Arg-II in activation of pulmonary fibroblasts via paracrine release of IL-1β and TGF-β1, contributing to pulmonary inflammaging and fibrosis. The results provide a novel mechanistic insight in the role of Arg-II in pulmonary aging.     

Modulation of mechanosensitive calcium-selective cation channels by temperature

Gating of associations of mechanosensitive Ca²⁺-selective cation co-channels in the plasmalemma of onion epidermis has a strong and unusual temperature dependence. Tension-dependent activity rises steeply as temperature is lowered from 25°C to about 6°C, but drops to a low level at about 5°C. Under the conditions tested (with Mg²⁺ and K⁺ at the cytosolic face of outside-out membrane patches), promotion results both from more bursting at all observed linkage levels and from longer duration of bursts of co-channels linked as quadruplets and quintuplets. Co-channel conductance decreases linearly, but only modestly, with declining temperature. It is proposed that these and related mechanosensitive channels may participate in a variety of responses to temperature, including thermonasty, thermotropism, hydrotropism, and both cold damage and cold acclimation.     

Correlation between arrested secondary plasmodesmal development and onset of accelerated leaf senescence in yeast acid invertase transgenic tobacco plants

Mature leaves of a transgenic tobacco plant ( Nicotiana tabacum L var. Samsun, line A41-10) that constitutively express a yeast-derived acid invertase gene develop symptoms which are characterized by the presence of greenish-yellow and green sectors in the same leaf, and onset of early, leaf senescence. Previous studies indicated that invertase activity was two- to threefold higher in the greenish-yellow sectors than in the green sectors. Our structural analyses revealed that development of secondary plasmodesmata, via modification of existing primary plasmodesmata, between mesophyll cells was inhibited severely in the greenish-yellow sectors, but only marginally in the green sectors. In contrast, the structure and function of primary plasmodesmata in the same symptomatic sectors remained unaltered as determined by structural and dye coupling studies. It is hypothesized that secondary plasmodesmata differ from primary plasmodesmata in having special abilities to traffic information molecules to coordinate leaf development and physiological function(s). Arrest of secondary plasmodesmal development by high invertase activity in the transgenic tobacco leaf may have prevented this type of trafficking and hence resulted in early leaf senescence. The results also indicate that the yeast acid invertase-expressing tobacco may provide an effective experimental system for the molecular characterization of cellular mechanisms that regulate the development, function, and possible turnover of secondary plasmodesmata.     

气候变化导致青藏高原马鹿种群适应性分布退缩：以类乌齐马鹿国家级自然保护区为例

近50年青藏高原的气候变化速率是全球平均值的2倍,对高原有蹄类的种群分布和多样性维持带来严重影响。本研究以西藏类乌齐马鹿国家级自然保护区的马鹿种群为例,通过2013年和2021年对马鹿和牦牛种群数量、分布的调查,并整合了物种分布模型和种群动态模型,评估了当前和未来气候变化及人类活动(放牧、道路、居民点等)对马鹿种群适应性分布的影响。研究表明,马鹿种群在2013—2021年由890头增加到1 400头,根据种群增长模型预计在2050年马鹿种群数量将达到1 735头,但其适宜栖息地在2050年代下降43.4%,2070年代下降5.1%,表明马鹿种群增长与适宜栖息地缩小之间的冲突将不利于马鹿种群的可持续发展。同时,当前马鹿与牦牛栖息地重合率为19%,2050年代为60%,2070年代为37%,且牦牛与马鹿存在食物竞争,这在一定程度上减少了马鹿原有的适宜栖息地。为保护马鹿,建议减少牦牛的饲养量1 000～1 500头。本研究将种群增长模型、种间竞争关系与物种分布模型整合,把气候变化对物种的影响延伸到种群层面,对其他物种的保护具有借鉴意义。