Alkyl-dihydroxyacetone phosphate synthase and dihydroxyacetone phosphate acyltransferase form a protein complex in peroxisomes.

Dihydroxyacetone phosphate (GrnP) acyltransferase and alkyl-GrnP synthase are the key enzymes involved in the biosynthesis of ether phospholipids. Both enzymes are located on the inside of the peroxisomal membrane. Here we report evidence for a direct interaction between these enzymes obtained by the use of chemical cross-linking. After cross-linking and immunoblot analysis alkyl-GrnP synthase could be detected in a 210-kDa complex which was located entirely on the lumenal side of the peroxisomal membrane. Two-dimensional SDS/PAGE demonstrated that GrnP-acyltransferase is also cross-linked in a 210-kDa complex. Co-immunoprecipitation confirmed that the two enzymes interact, in a heterotrimeric complex. Furthermore, alkyl-GrnP synthase can form a homotrimeric complex in the absence of GrnP-acyltransferase as was demonstrated by immunoblot analysis after cross-linking experiments with either GrnP-acyltransferase deficient human fibroblast homogenates or recombinant (His)6-tagged alkyl-GrnP synthase. We conclude that alkyl-GrnP synthase interacts selectively with GrnP-acyltransferase in a heterotrimeric complex and in the absence of GrnP-acyltransferase can also form a homotrimeric 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。     

Rates of mutation to growth factor autonomy and tumorigenicity differ in hematopoietic stem and precursor cells expressing the multilineage colony-stimulating factor gene.

At least two separate but interdependent events are required to attain autonomous growth as a consequence of ectopic expression of the multilineage colony-stimulating factor gene in hematopoietic progenitor cells. The rate at which the second event occurs is more than 3 orders of magnitude higher in precursor cell lines (FDC-P1 or FDC-P2) than in stem cell lines (FDC-Pmix). Autonomous, but not density-dependent, growth is tightly coupled to tumorigenicity in precursor cells; however, neither growth-factor-independent nor autonomously growing stem cell lines are tumorigenic.     

The rho gene product expressed in E. coli is a substrate of botulinum ADP-ribosyltransferase C3

The ras-related rho A protein expressed in E. coli, was ADP-ribosylated by botulinum ADP-ribosyltransferase C3. C3 also modified the valine-14 mutant rho protein but not the products of H-ras, R-ras, ral, ypt, and rap 1 genes. A ras-rho chimaera consisting of 60 amino acids from the amino terminus of ras fused to 133 amino acids from the carboxy terminus of rho was not modified by C3. Antibodies raised against the porcine brain cytosolic substrate of C3 cross reacted with the rho, valine-14 rho and ras-rho proteins, but not with the gene products of H-ras, R-ras, ral or rap 1. Polyclonal anti-H-ras antibodies cross reacted with H-ras but not with ral, rho, or the C3 substrate purified from porcine brain.     

Expression of the GM-CSF gene after retroviral transfer in hematopoietic stem cell lines induces synchronous granulocyte-macrophage differentiation

Multipotent murine stem cell lines (FDC-Pmix) depend on IL-3 for self-renewal and proliferation and can be induced to differentiate into multiple hematopoietic lineages. Single FDC-Pmix cells infected with retroviral vectors expressing GM-CSF are induced to differentiate into granulocytes and macrophages. This results in a complete loss of clonogenic cells if IL-3 is not exogenously supplied; however, multipotent variants can be selected that do not terminally differentiate if cells are kept in the presence of IL-3. Unidirectional and synchronous granulocyte and macrophage differentiation accompanied with loss of self-renewal capacity is induced when IL-3 is removed. Our data indicate that activation of the GM-CSF receptor induces differentiation of stem cells by an instructive mechanism that can be blocked by the activated IL-3 receptor. A model of how receptors can induce proliferation and cell-specific differentiation by two separate pathways is discussed.     

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.。     

Temporal events of gypsy moth vitellogenesis and ovarian development

Abstract The vitellogenic period of gypsy moth ovarian development starts on day 3 of the pupal stage and continues through adulthood. During this period, rapid increases occur in follicle size, protein content, and wet weight of the ovary. Patency is observed on day 3 of the pupal stage.
Pre-vitellogenic follicles are formed in the last larval stadium. Newly formed follicles detach from the germarium on day 4, and increase rapidly to 140 per ovariole at the end of the last larval stadium. The pre-vitellogenic follicles are uniformly around 50 um in diameter. No vitellogenin is incorporated into the oocytes until the pupal stage.
Polyacrylamide gel electrophosesis (PAGE) in the presence of sodium dodecylsulphate (SDS) analysis of male and female haemolymph samples and vitellogenic ovaries demonstrates the presence of two female-specific subunits of vitellogenin of 180 kD and 160 kD. These proteins are detected only in haemolymph and ovarian extracts of vitellogenic females. The molecular weight of the native protein determined by size exclusion chromatography is approximately 400–420 kD.
A highly sensitive double antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed to monitor the temporal changes in vitellogenin titre in haemolymph. Vitellogenin production starts on day 2 of the last larval stadium, reaching a maximum level by day 6 of the last larval stadium, and decreasing in the late pupal stage as vitellogenin was internalized into the oocytes. This is the first report of vitellogenin production occurring in the larval stage of a holometabolous insect. The fact that vitellogenin production and uptake occur during different stages of development in the gypsy moth, opens up some interesting questions concerning the underlying regulatory mechanisms controlling each process.