花生子叶生物反应器-花生产业中一支潜在的新生力量

花生子叶生物反应器具有产品部位特异、浓度高、可直接食用等优点。介绍了花生生物反应器需要的技术及该领域的研究现状和前景。花生生物反应器的关键是转基因载体的构建,花生主要贮藏蛋白的启动子是构建这种载体的最佳选择。大豆的Glycinin基因启动子也可用于构建花生生物反应器的转基因载体。     

The burning peanut

Visual selection occurs when predators preferentially remove conspicuous varieties from prey populations and thus confer a selective advantage on inconspicuous varieties. In previous papers we have described a general method for simulating such natural selection, and we here give details of an improvement that again uses wild birds as predators, green and brown pastry ‘baits’ as prey, and trays containing coloured stones as the backgrounds. We used backgrounds of three different colours: green (on which brown baits were conspicuous), brown (on which browns were inconspicuous), and white (on which both prey types were conspicuous). The important difference from the previous design was that these backgrounds were presented simultaneously on the same bird table. We placed equal numbers of green and brown prey on each background and recorded the numbers eaten by wild birds. We did six experiments to test the design. Two different methods of measuring selection showed that the results were generally in the direction predicted from the hypothesis that conspicuous prey are more likely to be eaten by predators.     

The macromolecular properties of peanut agglutinin

The dependence upon solution conditions of the quaternary structure and gross conformation of peanut agglutinin was examined by sedimentation equilibrium, sedimentation velocity, gel chromatography, and circular dichroism. At pH 8, the protein exists as a compactly folded tetramer of molecular weight 98,000. Between pH 4.75 and pH 3.0, the molecular reversibly dissociates to a (still globular) dimer. In the presence of denaturants such as SDS or guanidinium chloride, the protein dissociates to its four equal-sized constituents polypeptide chains. The circular dichroic spectrum of peanut lectin exhibits changes in the near ultraviolet upon binding of lactose, whereas the far ultraviolet spectrum remains unchanged. Dissociation to the dimeric state produces subtle changes in both the near and far ultraviolet circular dichroic spectrum.     

The amino acid sequence of peanut agglutinin

The amino acid sequence of peanut (Arachis hypogaea) agglutinin was determined from three major fragments obtained by mild acid cleavage at Asp-Pro peptide bonds. The sequence of 236 amino acids has residues identical to those that form the metal-binding site and the hydrophobic pocket in concanavalin A and other lectins, although the overall similarity is only 42%. In the segments of peanut agglutinin that correspond to the four loops that form the carbohydrate-binding site in concanavalin A and favin, several central residues are homologous, while others show changes to smaller side chains, such as Tyr----Gly. The carbohydrate-binding site of peanut agglutinin may therefore have a similar peptide-backbone architecture, but form a considerably more open cleft.     

The peanut lectin-binding glycoproteins of human epidermal keratinocytes

Peanut lectin (PNA) is known to bind more strongly to keratinocytes that are undergoing terminal differentiation than to proliferating keratinocytes, both in intact epidermis and in culture. In order to investigate the significance of this change in cell-surface carbohydrate we have identified the PNA-binding glycoproteins of cultured human keratinocytes and raised antibodies against them. Two heavily glycosylated bands of 110 and 250 kDa were resolved by PAGE of [14C]galactose- or [14C]mannose- and [14C]glucosamine-labeled cell extracts eluted with galactose from PNA affinity columns. The higher molecular weight band was also detected on PNA blots of unlabeled cell extracts transferred to nitrocellulose. Both bands were sensitive to Pronase digestion, but only the 250-kDa band was digested with trypsin. A rabbit antiserum that we prepared (anti-PNA-gp) immunoprecipitated both bands from cell extracts. In contrast to PNA, anti-PNA-gp bound equally to proliferating and terminally differentiating cells, indicating that some epitope(s) of the PNA-binding glycoproteins is present on the cell surface prior to terminal differentiation. When keratinocytes grown as a monolayer in low-calcium medium (0.1 mM calcium ions) were switched to medium containing 2 mM calcium ions in order to induce desmosome formation and stratification, there was a dramatic redistribution of the PNA-binding glycoproteins, which became concentrated at the boundaries between cells. This may suggest a role for the glycoproteins in cell-cell interactions during stratification.     

花生磷脂酶D的pH值记忆效应

研究了花生磷脂酶D（PLD）的pH值记忆效应,结果表明,花生PLD在冻干过程中具有pH值记忆效应。冻干PLD分散于有机溶剂中对pH值记忆效应的保持与溶剂种类有关。在所研究的有机溶剂范围内,冻干PLD分散于氯仿、二氯甲烷、乙醚、甲苯和正己烷中仍然能保持这种pH值记忆效应。但在苯中PLD氨基pKa变化较大,增加了0．738,说明PLD在苯中保持pH值记忆效应的能力较差。     

Survival of Salmonella in peanut butter and peanut butter spread

In 1996, the first documented outbreak of salmonellosis associated with the consumption of peanut butter was reported. This study was undertaken to determine survival characteristics of high (5.68 log10 cfu g(-1)) and low (1.51 log10 cfu g(-1)) inocula of a five-serotype mixture of Salmonella in five commercial peanut butters and two commercial peanut butter spreads. Populations in samples inoculated with 5.68 log10 cfu g(-1) and stored for 24 weeks at 21 or 5 degrees C decreased 4.14-4.50 log10 cfu g(-1) and 2.86-4.28 log10 cfu g(-1), respectively, depending on the formulation. The order of retention of viability was: peanut butter spreads > traditional (regular) and reduced sugar, low-sodium peanut butters > natural peanut butter. Differences in rates of inactivation are attributed to variation in product composition as well as size and stability of water droplets in the colloidal matrix, which may influence nutrient availability. With the exception of natural peanut butter, products initially inoculated with 1.51 log10 cfu of Salmonella g(-1) (32 cfu g(-1)) were positive for the pathogen after storage for 24 weeks at 5 degrees C. At 21 degrees C, however, with the exception of one peanut butter spread, all products were negative for Salmonella after storage for 24 weeks. Post-process contamination of peanut butter and spreads with Salmonella may to result in survival in these products for the duration of their shelf life at 5 degrees C and possibly 21 degrees C, depending on the formulation.     

N-malonyltransferases from peanut

Three distinct N-malonyltransferases were purified from peanut seedlings, accepting either anthranilic acid, D-tryptophan, or 3,4-dichloroaniline, respectively, as a substrate. Partially purified malonyl-CoA:D-tryptophan malonyltransferase also catalyzed the formation of the corresponding malonic acid conjugate when 1-aminocyclopropane-1-carboxylic acid was employed as a substrate. These N-malonyltransferases were clearly distinguished from several O-malonyltransferase activities also present in the same seedlings. N-Malonic acid conjugates have been previously isolated from peanut either as a natural constituent or after feeding with xenobiotics. By analogy to the results reported with cultured parsley cells, multiple malonyltransferases in peanut may have a role in vacuolar transport. Crude extracts of young peanut seedlings were incapable of hydrolyzing the respective N-malonic acid conjugates. However, dialyzed extracts of older plants released malonic acid from malonyl-1-aminocyclopropane-1-carboxylic acid but not from malonyl-3,4-dichloroaniline, suggesting that some N-malonic acid conjugates may be metabolized in plants which are approaching senescence.     

The phylogenetic relationship of possible progenitors of the cultivated peanut

The cultivated peanut (Arachis hypogaea L.) is an allotetraploid composed of A and B genomes. The phylogenetic relationship among the cultivated peanut, wild diploid, and tetraploid species in the section Arachis was studied based on sequence comparison of stearoyl-ACP desaturase and oleoyl-PC desaturase. The topology of the trees for both fatty acid desaturases displayed two clusters; one cluster with A genome diploid species and the other with B genome diploid species. The two homeologous genes obtained for each of the two fatty acid desaturases from the tetraploid species A. hypogaea and A. monticola were separated into the A and B genome clusters, respectively. The gene phylogenetic trees showed that A. hypogaea is more closely related to the diploid species A. duranensis and A. ipaensis than to the wild tetraploid species A. monticola, suggesting that A. monticola is not a progenitor of the cultivated peanut. In addition, for the stearoyl-ACP desaturase, the A. duranensis sequence was identical with one of the sequences of A. hypogaea and the A. ipaensis sequence was identical with the other. These results support the hypothesis that A. duranensis and A. ipaensis are the most likely diploid progenitors of the cultivated tetraploid A. hypogaea.     

The role of proline in thidiazuron-induced somatic embryogenesis of peanut

Summary Peanut seeds germinated on media supplemented with thidiazuron [TDZ: N-phenyl-N′-(1,2,3-thiadiazol-yl)urea], formed somatic embryos at the hypocotyledonary notch region by Day 35 of the culture period. Supplementation of the culture media with proline, thioproline, or glutamine reduced the total number of embryos formed, but the resulting embryos were larger, greener and had a more synchronous development than the regenerants formed on media containing TDZ alone. Analysis of the endogenous amino acid content of the germinating seeds during the induction phase of somatic embryogenesis revealed accumulation of proline to 6% of the dry seed weight. Concurrent with the emergence of the radicle, the proline concentration remained significantly elevated throughout the expression phase of embryogenesis. Several other amino acids including alanine, aspartate, asparagine, glutamate, glutamine, γ-aminobutyrate (GABA), hydroxyproline, isoleucine, threonine and valine accumulated to peak values approximately 10-fold higher than those of the controls. These results indicate that proline plays a key role in directing the route of TDZ-induced somatic embryogenesis and that TDZ effectively stimulates a cascade of metabolic events resulting in the production of specific metabolites, including amino acids, required for the regenerative process.     

The prisoner reentry industry

The Prisoner Reentry Industry found its beginnings in the recognition that men and women who were being released from prison continued to need assistance in their transition process. Depending upon the individual needs of each person, this determined the extent of what type of assistance needed. Within a short period of time it was determined that the greatest assistance was needed in the area of housing and employment. However, once a person completed this transition phrase that was usually understood to be about three years, the following questions arise: when does the reentry phase end? When does society allow the ex-offender to move on with their lives? Even when secure employment has been maintained, when other areas of the individuals’ life are functioning “at least like everyone else in society”, when does the reentry stop and the ex-offender allowed to enter into mainline society? This article attempts to show that we have not done a good job of allowing the ex-offender to move from the phase of prisoner reentry to the phase of contributor in our society.     

The Brazilian biofuels industry

Ethanol is a biofuel that is used as a replacement for approximately 3% of the fossil-based gasoline consumed in the world today. Most of this biofuel is produced from sugarcane in Brazil and corn in the United States. We present here the rationale for the ethanol program in Brazil, its present 'status' and its perspectives. The environmental benefits of the program, particularly the contribution of ethanol to reducing the emission of greenhouse gases, are discussed, as well as the limitations to its expansion.