Genes encoding oleosins in maize kernel of inbreds Mo17 and B73

We have investigated all three oleosin genes which are expressed in the kernel of maize (Zea mays L., Mo17). Oleosin genes, ole16, ole17, and ole18, encode OLE16, OLE17, and OLE18, respectively, in proportional amounts of approximately 2:1:1 in isolated oil bodies. None of the three genes has an intron or a sequence encoding an N-terminal signal peptide. The three genes are expressed coordinately during seed maturation, and their encoded oleosins are present in similar proportional amounts in oil bodies isolated from the embryonic axis, scutellum, and aleurone layer. OLE16 represents one oleosin isoform, whereas OLE17 and OLE18 are close members of another oleosin isoform. ole16 and ole18 have been mapped to single loci on chromosomes 2 (near b1 gene) and 5S (near phya2), respectively. We predict that ole17 is located on chromosome 1 (near phya1), in a chromosomal segment duplicated on chromosome 5.     

绒毡层小体,一种在花药绒毡层细胞中新发现的含油细胞器

绒毡层小体(tapetosome)是最近新发现的特异性出现在花药绒毡层细胞中的一种含油细胞器。现对这种细胞器的形态、结构、生化组成、与其他含油细胞器的不同以及它们在花粉外被形成过程中的作用和作用机制进行综述。     

黄连木果实中油体的发育

黄连木（Pistacia chinensis）是一种重要的木本油料植物,其果实中贮存着大量的油脂,这些油脂分子主要存在于果皮、种皮和胚的油体中。在光学显微镜下观察发现,果皮中油的积累开始于果实发育晚期,果皮开始变红时;种皮中油体的发育开始于果实发育早期;胚中油体的发育开始于球形胚时期。透射电子显微镜观察结果显示,种皮和胚中的油体形成于内质网,而果皮中的油体则分别由内质网、质体和液泡形成。尼罗红荧光标记显示,内质网形成的油体始终以独立单元的形式存在。种皮和胚中也贮藏蛋白体,但发育晚于油体。果皮、种皮和子叶中都贮存少量的淀粉粒。     

利用植物生物反应器生产药用蛋白质

植物生物反应器是一种安全、环保、廉价的生产系统。它已成为生产药用蛋白质的理想载体并受到广泛的关注。目前,生物反应器通过靶向表达来提高外源蛋白质产量取得了一定的效果。本文简要介绍了生物反应器的选择,并着重阐述了通过在空间上的定位表达和时间上的诱导表达来提高药用蛋白质产量方面的最新研究进展,同时展望了未来的发展前景。     

The transmembrane domain of surfactant protein C precursor determines the morphology of the induced membrane compartment in CHO cells

Surfactant protein C (SP-C) is a small lipopeptide of which the main part consists of a typical valyl-rich transmembrane domain. The protein is expressed as a propeptide (proSP-C) which is processed and sorted via the regulated secretory pathway to the lamellar body, where mature SP-C is stored before secretion into the alveolar space. In this study we investigated the identity of the compartment to which proSP-C is sorted in cells that do not have a regulated secretory pathway, such as CHO cells. By electron microscopy we determined that proSP-C was localized in an uncommon membrane compartment with very regular morphology, which was not present in control cells. This membrane compartment is not influenced by the palmitoylation of proSP-C and is probably derived from the endoplasmic reticulum. However, proSP-C chimeras with artificial transmembrane domains induced a membrane compartment with a different morphology. Therefore we propose that the typical amino acid sequence of the transmembrane domain of proSP-C plays a role in membrane formation and morphology, which may be relevant under physiological conditions.     

种子的贮油细胞器——油体及其蛋白

生物柴油作为一种可再生的替代能源,因其良好的环境效应而倍受关注.植物油是生产生物柴油的主要原料.植物油作为最经济、最有利于种子传播和萌发生长的能量和碳源物质,贮存和积累于植物种子的贮油细胞器-油体之中.本文综述了植物种子油体的亚细胞结构、化学组成及其功能、生物合成与降解等的研究进展.     

Stable constitution of artificial oil body for the refolding of IGF1

Over-expression of oleosin-fused IGF1 results in the formation of insoluble aggregates in Escherichia coli occupying 35% of total proteins. In this study, a method based on artificial oil body (AOB) was applied to obtain active IGF1, insulin-like growth factor 1, from its insoluble form in one step. The stability of AOB emulsions constituted with soybean oleosin was maximized in the optimal composition of TAG (97.04%, wt/wt), PL (1.14%, wt/wt), and oleosin-UbIGF1 (1.82%, wt/wt) at pH 7.5 and at 25°C. Upon sonication, the mixture comprising plant oil and the insoluble fusion protein was readily assembled into AOBs. After peptide cleavage mediated by endopeptidase, the IGF1 free of fusion tags was liberated and then recovered. Subsequently, IGF1 self-refolded on AOB was obtained with high yield of 63.2 mg/g dry cell. This on-AOB refolding can be applied to the development of bacterial expression and purification of other active recombinant proteins.     

Proteomic analysis of oil body membrane proteins accompanying the onset of desiccation phase during sunflower seed development

A noteworthy metabolic signature accompanying oil body (OB) biogenesis during oilseed development is associated with the modulation of the oil body membranes proteins. Present work focuses on 2-dimensional polyacrylamide gel electrophoresis (2-D PAGE)-based analysis of the temporal changes in the OB membrane proteins analyzed by LC-MS/MS accompanying the onset of desiccation (20–30 d after anthesis; DAA) in the developing seeds of sunflower (Helianthus annuus L.). Protein spots unique to 20–30 DAA stages were picked up from 2-D gels for identification and the identified proteins were categorized into 7 functional classes. These include proteins involved in energy metabolism, reactive oxygen scavenging, proteolysis and protein turnover, signaling, oleosin and oil body biogenesis-associated proteins, desiccation and cytoskeleton. At 30 DAA stage, exclusive expressions of enzymes belonging to energy metabolism, desiccation and cytoskeleton were evident which indicated an increase in the metabolic and enzymatic activity in the cells at this stage of seed development (seed filling). Increased expression of cruciferina-like protein and dehydrin at 30 DAA stage marks the onset of desiccation. The data has been analyzed and discussed to highlight desiccation stage-associated metabolic events during oilseed development.     

Zonal changes in the rat liver following an acute dose of phenobarbitone: An ultrastructural,morphometric and biochemical correlation

Alterations in the liver of rats 6 h after a dose of phenobarbitone have been studied by subcellular fractionation, conventional electron microscopy and morphometric analysis. The area immediately surrounding the central vein was the only area to undergo any alterations. There was a morphometrically measurable but not observable cellular hypertrophy of 71% whilst the hepatocyte complement of rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER) was increased by 72% and 93% respectively. The increases in RER and SER were not apparent by observation and it is assumed that they have been diluted by the cell hypertrophy to 1% and 22% which must be below the threshold for detection by subjective observation. Following subcellular fractionation and measurement of microsomal protein, there was no significant difference in the level of microsomes isolated from control or treated rats. Therefore, the morphometrically measured increase in RER and SER would appear to be restricted to a relatively small population of hepatocytes adjacent to the central vein. Such an increase would represent only a small percentage of total microsomes in a homogenate and would almost certainly be masked by variation in animals and techniques. Disruption of RER was also observed in hepatocytes that would proliferate their SER should phenobarbitone treatment have been continued. Therefore this RER disruption would seem in no way to interfere with the process of membrane and enzyme synthesis.     

Zonal changes in the rat liver after chronic administration of phenobarbitone in ultrastructural, morphometric and biochemical correlation.

Alterations in the liver of rats subjected to 24 days of continuous administration of phenobarbitone have been supplied bu subcellular fractionation, conventional electron microscopy and morphometric analysis. The increase in wet weight of the liver was found to result from a combination of cellular hypertrophy, hyperplasia and an enlarged hepatic blood space. In the centrilobular zone all the hepatocytes underwent a substantial proliferation of total ER, became enlarged and had an increased blood supply. However, in the periportal zone phenobarbitone caused changes in only 45% of the hepatocytes, the remainder being apparently resistent or tardy. An overall dramatic increase in hepatic RER was both measured and observed but the response involved hepatocytes in which the RER had proliferated as well as those which were depleted of RER or had stacks and cisternae that were severely shortened and dispersed. These alterations are discussed in relation to changes in RER after administration of agents causing hepatonecrosis. Possible reasons for the inability of other workers to detect a phenobarbitone-induced increase in RER are also put forward. After subcellular fractionation and corection for centrifugation losses into the 9500 g pellet, using the microsomal marker cytochrome P-450, phenobarbitone-induced increase in total ER was substantially less than that found by morphometric analysis. This indicates that during the preparation of microsomes a substantial proportion of intracellular membranes, having different metabolic and synthetic properties to those finally isolated, are discarded and emphasizes the need to exercise care when using microsomal preparations.     

Evidence for a Nonendosomal Function of the Saccharomyces cerevisiae ESCRT-III-Like Protein Chm7

Endosomal sorting complex required for transport (ESCRT) proteins are involved in a number of cellular processes, such as endosomal protein sorting, HIV budding, cytokinesis, plasma membrane repair, and resealing of the nuclear envelope during mitosis. Here we explored the function of a noncanonical member of the ESCRT-III protein family, the Saccharomyces cerevisiae ortholog of human CHMP7. Very little is known about this protein. In silico analysis predicted that Chm7 (yeast ORF YJL049w) is a fusion of an ESCRT-II and ESCRT-III-like domain, which would suggest a role in endosomal protein sorting. However, our data argue against a role of Chm7 in endosomal protein sorting. The turnover of the endocytic cargo protein Ste6 and the vacuolar protein sorting of carboxypeptidase S (CPS) were not affected by CHM7 deletion, and Chm7 also responded very differently to a loss in Vps4 function compared to a canonical ESCRT-III protein. Our data indicate that the Chm7 function could be connected to the endoplasmic reticulum (ER). In line with a function at the ER, we observed a strong negative genetic interaction between the deletion of a gene function (APQ12) implicated in nuclear pore complex assembly and messenger RNA (mRNA) export and the CHM7 deletion. The patterns of genetic interactions between the APQ12 deletion and deletions of ESCRT-III genes, two-hybrid interactions, and the specific localization of mCherry fusion proteins are consistent with the notion that Chm7 performs a novel function at the ER as part of an alternative ESCRT-III complex.     

Inositol (1,4,5)trisphosphate-promoted Ca2+ release from microsomal fractions of rat liver

Crude mitochondrial fractions containing a substantial amount of microsomes accumulate Ca2+ in the presence of ATP, ruthenium red and oligomycin. A proportion of this accumulated Ca2+ is released by the addition of low concentrations (ca. 1 microM) of inositol (1,4,5) trisphosphate . Under some conditions the release is transient, and evidence is presented which suggests that this is due to inhomogeneity in the vesicle population. (1,4,5)inositol trisphosphate -induced Ca2+ release can also be demonstrated, under appropriate experimental conditions, in a more purified microsomal fraction essentially free of mitochondria.     

Ultrastructural dynamics of the corpus allatum of Choleva angustata Fab. (Coleoptera,Catopidae)

Summary The ultrastructure of the corpora allata (CA) during postembryonic stages of Choleva angustata Fab. shows cyclic changes, in particular regarding the endoplasmic reticulum and the mitochondria. During the last larval instar, at the short transitory period which follows the cessation of alimentation, we observed a highly unusual appearance of the CA, characterized by intensive vacuolization. After this transitory period, the smooth endoplasmic reticulum (ser) disappears until the imago emerges. These observations along with our experimental data permit a physiological interpretation.We thank Departments of Electron Microscopy and Photography of the Institute of Neurophysiology and Psychophysiology, C.N.R.S., Marseille, France