Redistribution of cell surface transferrin receptors prior to their concentration in coated pits as revealed by immunoferritin labels

Summary Immunocytochemistry has been used to study distribution of cell surface transferrin receptors in erythroid, leukemic (K562) cells. The cells were fixed and labelled with monoclonal (OKT-9) anti-transferrin receptor antibodies; the antibody-labelled receptors were then detected by either immunofluoresceinor immunoferritin-antimouse-antibody conjugates. Typically, the immunoferritin labels were distributed diffusely at the non-coated regions of the cell surface as well as concentrated in the clathrincoated pits. To examine further this pattern of distribution, cells were labelled at 0° C and then warmed to 37° C for zero to 30 min prior to fixation. The majority of the immunoferritin labels were initially dispersed in small groups at the non-coated regions of the cell surface (mean = 6 immunoferritin labels/cluster), but larger groups were common subsequent to incubation at 37° C (mean = 13 immunoferritin labels/cluster). However, the size of immunoferritin labels in the coated pits was unchanged (mean = 12 immunoferritin labels/pit). Immunoferritin labels were typical in coated and uncoated vesicles l min after warming to 37° C, but common in endosomes, multivesicular bodies and lysosomes by 30 min. It appears that single cell-surface receptors form large aggregates prior to their concentration in coated pits. Coated vesicles, uncoated vesicles, and endosomal vacuoles may together form the non-lysosomal compartment where the internalized receptors might be dissociated from the ligands (antibodies).     

Redistribution and unmasking of Annexin V binding sites in apoptotic Raji cells

The complement receptor type 2 (CR2) associates with other surface antigens and proteins and its redistribution and/or unmasking occurs through still unknown mechanism(s). The data presented demonstrate that high-density cultured CR2-positive cells undergo apoptosis and that the redistribution and unmasking of Annexin V binding sites occurs in a fashion similar to the redistribution and unmasking of CR2. Therefore, apoptotic and non apoptotic cells from the same lineage may share a similar mechanism for the exposition of neo-surface markers     

Larval recruitment of the blue mussel Mytilus edulis: The effect of flow and algae

The mussel Mytilus edulis settlement and distribution was studied on plastic panels with manipulated flow regime (faired, bluff, split and angled) with or without water soluble metabolites of the green alga Cladophora rupestris. The panels were exposed vertically on a device (hydrovane) that ensures their constant orientation in the current during the peak of larval settlement at 1 m depth. In order to investigate larval distribution on the panels, half of them were coated with a silicone vacuum grease that prevents larvae from de-attachment. This grease was not toxic and did not attract or repel larvae. Low densities of larvae on the un-greased plates compared to the greased ones suggested that some of larvae left the substratum. The blue mussel larvae initially settled in regions of reduced shear velocity and then redistribute to the regions of high shear velocity. The presence of the alga increased the density of blue mussel larvae and changed their distribution on the panels. Overall, our results demonstrated that larval recruitment of M. edulis is an active process affected both by boundary-layer hydrodynamics and algal waterborne compounds.     

Redistribution of nitrogen in an ecosystem due to long-term fertilization and continuous cropping

Summary When a leguminous crop like cowpea was included in a crop rotation of Ganga 5 maize, CO 7 ragi and CO 2 cowpea, the total nitrogen content in the soil was considerably increased even in the unfertilized plots. The leguminous crop fixed atmospheric nitrogen at the rate of 205 kg N/hectare/year. Potassium did not influence the status whereas phosphorus, over a background of N, improved it. Considerable quantity of N fixed was observed to have been redistributed in the soil which depended on the fertilization pattern.     

育苗移栽对麦套棉^14CO2同化量及运转分配的影响

育苗移栽不仅使陆地棉(Gossypium hirsutum L.)株在苗期、蕾期、花铃期的(14)~CO_2同化强度和同化量显著提高,而且对上述各生育期同化产物向籽棉的再动员具有明显的促进作用。各期标记后3d的测定结果显示,育苗移栽增加了棉苗同化物质向根系中的分配而减少了向顶芽的分配,有利于促根壮苗;使蕾期同化物质向顶芽和边心的分配比例下降,有利于控制棉花的营养生长,防止或减轻茎叶狂长,使棉株健壮稳长,促进花芽分化;在花铃期,促使更高比例的同化物质向成铃中分配,有利于蕾铃发育。     

Construction of the plasmid for expression of ETA-EGFP fusion protein under control of the cytomegalovirus promoter and its effects in HeLa cells

Tumor-targeted vectors encoding toxic protein genes are promising tools for treating malignant tumors. We used the pEGFP-N1 vector to construct a novel plasmid (pCMV-ETA-EGFP) for eukaryotic expression of a truncated Pseudomonas aeruginosa exotoxin A (ETA) that is known to inhibit protein synthesis, and subsequently induce cell death, by inactivation of elongation factor-2. ETA was linked to the enhanced green fluorescent protein (EGFP) gene, and ETA-EGFP gene expression was driven by the cytomegalovirus (CMV) promoter. The time-lapse effects of pCMV-ETA-EGFP expression were examined in transiently transfected HeLa cells. HeLa cells transfected with pCMV-ETA-EGFP or cotransfected with pCMV-ETA-EGFP and рЕGFP-N1 showed lower fluorescence intensity than cells transfected with pEGFP-N1 alone. Analysis of the number of dead cells further confirmed the highly toxic effect of the ETA-EGFP fusion protein on cells transfected with pCMV-ETA-EGFP or cotransfected with pCMV-ETA-EGFP and рЕGFP-N1. ETA-EGFP fusion protein induced apoptotic cell death through the caspase-3 activation. By using the antibody against a marker nucleolar antigen A3 [Grigoryev, A.A., Bulycheva, T.I., Sheval, E.V., Kalinina, I.A., Zatsepina, O.V., 2008. Cytological indicators of the overall suppression of protein synthesis revealed by staining with new monoclonal antibody. Cell Tissue Biol. 2, 191–199], the distribution of which changes when HeLa cells are treated with known translation inhibitors, we obtained evidence to support the idea that protein synthesis is inhibited in transfected cells in situ. ETA-EGFP fusion protein was identified in lysates of transfected cells using anti-GFP-BL antibodies. Collectively, our results indicate that HeLa cells transfected with pCMV-ETA-EGFP synthesize the ETA-EGFP fusion protein that efficiently inhibits protein synthesis, leading to massive cell death by an apoptosis-mediated pathway with a participation of caspase-3. The constructed vector can be used in suicidal gene therapy of cancer and may also be useful for investigating the general effects of translational downregulation in human cancer cells. We also suggest a novel approach for detecting the activity of new vectors in transfected cells, which is based on the redistribution of nucleolar proteins in transfected cells.     

雨强对黄土坡面土壤水分入渗及再分布的影响

基于典型黄土的坡地人工降雨实验,对比研究了降雨、入渗及再分布规律;以雨强为主要影响因素,分析了降雨入渗及水分再分布过程中水土物质迁移的定量关系．结果表明,雨强变化对黄土坡面降雨入渗及土壤水分再分布的微观水分运动过程具有重要影响．雨强增大时,入渗和再分布湿润锋均随降雨历时延长而逐渐增加,但水分再分布过程的湿润锋增加速率比入渗慢得多;入渗湿润锋与时间关系可用幂函数表示,同时可表示为雨强的幂函数关系．再分布湿润锋与时间也存在定量关系．雨强越大,初始和稳定的土壤水分入渗率越高,累积入渗量随降雨时间增加得越快．此外,雨强越大,坡顶与坡脚湿润锋深度差异越小,坡面再分布过程的土壤含水量在各层的差异和递减趋势越明显．     

Effect of Seedling Transplantation on the14CO2 Assimilation and the Apportionment of 14C ssimilations Within the Cotton Plant Interplanted in Standing Wheat

Using 14C tracer technique, the effect of cotton ( Gossypium hirsutum L. ) seedling transplantation on the 14C assimilates and 14CO2 assimilate distribution as well as redistribution were studied. It was shown that transplantation of seedlings increased both 14C assimilates and their retmnslocation in cotton seedling markedly. The distribution of 14C assimilates in the plant organs 3 days after labelling indicated that transplantation could increase the translocation of 14C assimilates into the roots and main stem, but decrease it into the tip of cotton seedling, which benefited in establishing good quality of the seedling. Furthermore, the apportionment of 14C assimilates into growing points decreased, in favor of avoiding or reducing spindling of stead growth and improving the developement of florat buds. From bloom to boll great increase of the apportionment of 14C assimilates into bolls of the transplanted plant could promote the growth and the development of squares and bolls.     

Cytochemieal Observation on Garlic Clove before and after Temperature-Modulated Break of Dormancy

Usually, garlic clove keeps itself in dormancy during summer months and tends to break their dormancy as the climate becomes cooler toward autumn. Prolonged storage of garlic clove under relatively high temperature is a good measure taken in practics to retain its dormancy and refrain from sprouting. In fact, if garlic is stored around 30 ℃, its dormancy can be extended to more than six months while its exposure to low temperature (4 ℃) for a short duration will eventualy break its dormancy. The Dormant release can be diagnosed in the upper epidermis by signs of nuclear disintegration and appearance of APase, ATPase and POase activities. The nuclei in dormant epidermal cells keep their characteristic round shape and in the central position of the cells which are devoid of the enzyme activities mentioned. In case the clove is kept in 30℃ over a year, partial disintegration of the cells evacuation of the constituents also take place, as clearly shown by numerous proteinaceous granules suspended in the interior and by “nuclear extrusion” across the intercellular boundary.     

Redistribution of tissue zinc pools during lactation and dyshomeostasis during marginal zinc deficiency in mice

Zinc (Zn) requirements are increased during lactation. Increased demand is partially met through increased Zn absorption from the diet. It is estimated that 60–80% of women of reproductive age are at risk for Zn deficiency due to low intake of bioavailable Zn and increased demands during pregnancy and lactation. How Zn is redistributed within the body to meet the demands of lactation, and how Zn deficiency affects this process, is not understood. Female C57bl/6J mice were fed a control (ZA; 30 mg Zn/kg) or a marginally Zn deficient (ZD; 15 mg Zn/kg) diet for 30 days prior to mating through mid-lactation and compared with nulliparous mice fed the same diets. While stomach and plasma Zn concentration increased during lactation in mice fed ZA, mice fed ZD had lower stomach Zn concentration and abrogated plasma Zn levels during lactation. Additionally, femur Zn decreased during lactation in mice fed ZA, while mice fed ZD did not experience this decrease. Furthermore, red blood cell, pancreas, muscle and mammary gland Zn concentration increased, and liver and adrenal gland Zn decreased during lactation, independent of diet, while kidney Zn concentration increased only in mice fed ZD. Finally, maternal Zn deficiency significantly increased the liver Zn concentration in offspring but decreased weight gain and survival. This study provides novel insight into how Zn is redistributed to meet the increased metabolic demands of lactation and how marginal Zn deficiency interferes with these homeostatic adjustments.