Murine Ia-associated invariant chain's processing to complex oligosaccharide forms and its dissociation from the I-Ak complex

The processing of murine invariant chain (Ii) to a cell surface form bearing complex N-linked oligosaccharides has been demonstrated in the B cell lymphoma, AKTB-1b. In addition, the rate of processing of pulse-labeled Ii has been determined relative to its rate of dissociation from the alpha/beta complex of I-Ak. Ii, alpha-, and beta-chains were immunoprecipitated with anti-I-Ak or anti-Ii monoclonal antibodies. The heretofore uncharacterized complex oligosaccharide form of Ii (Ii-c) was identified in gel-purified immunoprecipitates by peptide mapping with reverse-phase HPLC. Ii-c is resistant to deglycosylation by Endo H, which is specific for high-mannose N-linkages, but can be digested with Endo F, a glycosidase capable of cleaving both complex and high-mannose N-linked oligosaccharides. Immunoprecipitation of surface iodinated cells indicates that Ii-c is expressed on the plasma membrane. Pulse-chase metabolic labeling data show that the processing of Ii to Ii-c occurs with a t1/2 of about 120 min. In contrast, the processing of both alpha- and beta-chains of I-Ak to complex forms occurs with a t1/2 of 15 to 20 min. Our data show that Ii-hm begins to dissociate rapidly from the I-Ak complex after 100 to 120 min of chase. Only a small amount (less than 5% on a per mole basis) of Ii-c was found associated with the I-Ak complexes after 300 min of continuous metabolic labeling. These results are consistent with Ii serving as a carrier for Ia antigens as they are transported to the cell surface. In addition, they suggest that the processing of Ii to Ii-c, or a late processing event of the alpha- and beta-chains, such as their sialylation, may be a possible mechanism for inducing the dissociation of Ii from the I-Ak complex.     

酸敏感离子通道与脑梗死

急性脑梗死约占全部脑卒中的70%,病死率和致残率高,且极易复发。但目前针对急性脑梗死在时间窗内溶栓、抗凝等治疗手段不能从根本上切实有效地修复受损脑组织,且伴有出血等风险。寻找脑梗死形成发展的原因并予以治疗迫在眉睫。酸中毒是引起缺血性脑损伤的重要机制。大量实验研究表明,酸中毒能加重神经元的缺血性损伤,且其梗死面积与酸中毒的程度直接相关。但缺血产生的酸中毒如何引起神经元损伤的确切机制尚不明确。最近研究发现酸中毒能激活一种在中枢及周围神经中广泛存在的膜通道,即酸敏感离子通道,它对Ca2+通透,能引起细胞内Ca2+超载,同时能激活胞内酶引起细胞内蛋白质、脂类及核酸的降解,加重缺血后脑损伤。本文就酸敏感离子通道1a与脑梗死做一综述。     

黑龙江省三江平原丹顶鹤的数量分布

在地面调查的基础上,我们使用Y-11轻型飞机对黑龙江省三江平原地区的丹顶鹤的数量分布近行了调查,调查时飞行高度80米,航速140公里/小时,续航里程共3748公里。调查结果表明,丹顶鹤在三江平原主要分布在8个地区,其中嘟噜河下游、洪河自然保护区、七星河流域和兴凯湖低地是主要繁殖地,总数量共309只。     

Prolonged increased responsiveness of canine peripheral airways after exposure to O3

Because it is relatively insoluble, the oxidant gas O3 may penetrate to small peripheral airways when it is inhaled. Increased responsiveness in large airways after O3 breathing has been associated with the presence of inflammatory cells. To determine whether O3 produces prolonged hyperresponsiveness of small airways associated with the presence of inflammatory cells, we exposed the peripheral lungs of anesthetized dogs to 1.0 ppm O3 for 2 h using a wedged bronchoscope technique. A contralateral sublobar segment was simultaneously exposed to air as a control. In the O3-exposed segments, collateral resistance (Rcs) was increased within 15 min and remained elevated approximately 150% throughout the 2-h exposure period. Fifteen hours later, the base-line Rcs of the O3-exposed sublobar segments was significantly elevated, and these segments demonstrated increased responsiveness to aerosolized acetylcholine (100 and 500 micrograms/ml). There were no differences in neutrophils, mononuclear cells, or mast cells (numbers or degree of mast cell degranulation) between O3 and air-exposed airways at 15 h. The small airways of the lung periphery thus are capable of remaining hyperresponsive hours after cessation of localized exposure to O3, but this does not appear to be dependent on the presence of inflammatory cells in the small airway wall.     

四川省西部鱼类寄生粘孢子虫——1.粘体虫属六新种(粘孢子纲:双壳目)

本文报导四川省西部鱼类寄生粘孢子虫粘体虫属六新种,即异型粘体虫,新种Myxosoma disparis sp.nov.,四川粘体虫,新种Myxosoma sichuanensis sp.nov.,光唇粘体虫,新种Myxosoma acrossochilusi sp.nov.鳅粘体虫,新种Myxosoma nemachilusi sp.nov.斜囊粘体虫,新种Myxosoma obliqua sp.nov.,雅安粘体虫,新种Myxosoma yaanensis sp.nov.。     

Capitalist Philanthropy and Russian Revolutionaries: The Jesup North Pacific Expedition (1897-1902)

This review of the Jesup North Pacific Expedition, still the most important expedition in American anthropology, gives an idea of the goals and hazards of fieldwork around 1900, the pitfalls of international research, the tensions between anthropologists and host populations, the careers of early anthropologists, the role of private philanthropy, and the character of anthropology at the turn of the century. Franz Boas was the Expedition's linchpin. His organization of the Expedition, the way he handled problems, and his personal concerns reveal aspects of his view of anthropology and some of his basic attitudes.     

云南叶螨属一新种(蜱螨目:叶螨科)

在鉴定云南叶螨标本时,发现叶螨属一新种,现记述如下。模式标本保存于上海农学院。本文量度单位均为微米。 食禾叶螨Tetranychus graminivorus新种(图1—14) 雌螨 体长(包括喙)454,宽298。椭圆形。浅黄绿色。须肢端感器圆柱形,长6.8,     

中国东北地区常见有瓣蝇类调查初步报告

与人类杂处的蝇类,在我国东北地区的分布情况尚少系统调查。作者于1956年5月、8月曾赴内蒙东北部(伊图里河、图里河),6月、7月赴营口、盘山(田庄台),借这些机会,顺便采集了蝇类标本;同年9月组内同志去绥中也采回部分标本;1957年5月至10月作者又赴吉林、辽宁两省各地进行了蝇类调查。其中有瓣蝇类已经定名的共计5科26属68种,有6种为国内新记录。兹将结果报告如下: