Serological identification and molecular characterization of B (A) 02 subtype in patients and blood donors from Eastern China

This study was designed to identify the rare?type?ABO?blood?groups, B(A) 02, from Eastern China. Three samples with discordant serological results during routine blood type identification and four samples from one sample’ family were selected. All of them were detected by serological method. The exon 6 and 7 of the ABO genes were amplified by PCR and sequenced. They were typed as AsubB by serology and as BO by genotype. In AsubB samples, nt 700C>G mutation was detected in B gene, which was previously defined as B(A)02 alleles. In these seven samples, six showed B(A)02/O01 and one showed B(A)02/O02.B(A)02 allele was found to be more common in this study than B(A)04 which is considered to be more frequent than B(A)02. The careful identification of rare blood types is important for the safety of clinical blood transfusion.     

Expression of functional hexahistidine-tagged ricin B in tobacco

Ricin B (RTB), the lectin subunit of ricin, shows promise as an effective mucosal adjuvant and carrier for use in humans. In order to obtain a recombinant plant source of RTB that is devoid of the toxic ricin A subunit, we expressed RTB in Nicotiana tabacum. RTB was engineered with an N-terminal hexahistidine tag (His-RTB), which may affect protein stability. Lactose-affinity purification of His-RTB from leaves yielded three major glycosylated products of 32, 33.5 and 35 kDa. Their identity as RTB was verified by mass spectrometry and immunoblotting with anti-ricin antibodies. Functionality of His-RTB was confirmed by binding to asialofetuin, lactose and galactose.     

The mycotoxin fumonisin B1 inhibits eukaryotic protein synthesis: in vitro and in vivo studies

Inhibitory action of Fumonisin B₁ (FB₁) on eukaryotic protein synthesis was investigated, both in animal and plant system, and was compared with cycloheximide. Inhibitory effect of FB₁ was monitored in the TCA precipitable proteins of rabbit reticulocyte lysates exposed to various concentrations of the mycotoxin (0.0013–2.76 mM), using ³⁵ S-methionine as a tracer. FB₁ inhibited the protein synthesis by 6%, at 0.0013 mM and by 88%, at a higher concentration of 2.76 mM. Cycloheximide at a concentration of 0.355 mM was found to inhibit protein synthesis by 88%. Inhibitory action of FB₁ (1 mg kg⁻¹ body mass and a higher dose of 10 mg kg⁻¹ body mass) or cycloheximide (10 mg kg⁻¹ body mass; positive controls), injected intra-peritoneally into BALB/c mice was studied using ¹⁴C-l-Leucine as a tracer. FB₁ at lower dose of 1 mg kg⁻¹ body mass inhibited protein synthesis in liver by 8% and at a higher dose of 10 mg kg⁻¹ body mass by 38% in the BALB/c mice, when compared to cycloheximide which inhibited protein synthesis by 61%. The effects of FB₁ on protein synthesis in plant system was studied in germinated maize seedlings exposed to FB₁ at 0.9 μM, 0.009 mM and 0.09 mM concentrations, using ¹⁴C-l-Leucine as a tracer. Fumonisin B₁ at low, middle, and higher concentrations (0.9 μM, 0.009 mM, and 0.09 mM) inhibited protein synthesis in the seedlings by 4%, 12% and 22%, respectively. The inhibitory effects of FB₁ on the protein synthesis in the animal system in vitro and in vivo conditions, and in the plant system were found to be dose-dependent, though it was less potent compared to cycloheximide.     

Gigantonoclea guizhouensis Gu et Zhi 的叶部解剖研究

一、材料来源和研究方法解剖研究所用的D-1标本是笔者于1984年5月在贵州水城大河边煤矿二采区新开辟的运输巷侧壁砂岩中采到的,其层位经对比与田宝霖和张连武(1980)描述的水城汪家寨矿区综合地层柱中龙潭组下部第8分层的中部砂岩相当。该叶片沉积时受水流冲击,以中脉为对称轴向远轴侧对折成约20°角状(图版Ⅰ,图2)。     

Synthesis of a Brassica trigenomic allohexaploid (B. carinata × B. rapa) de novo and its stability in subsequent generations

Allopolyploidy plays an important role in plant evolution and confers obvious advantages on crop growth and breeding compared to low ploidy levels. The present investigation was aimed at synthesising the first known chromosomally stable hexaploid Brassica with the genome constitution AABBCC. More than 2,000 putative hexaploid plants were obtained through large-scale hybridisation from various combinations of crosses between different cultivars of Brassica carinata (BBCC) and B. rapa (AA). The majority of plants after two generations of selfing within selected hexaploid plants (H₂) were aneuploid, and only 80 plants (4.6%) had the expected hexaploid chromosome number (2n = 54). The hexaploid ratio increased to an average of 23.0 and 26.3% in the H₃ and H₄ generations, respectively, and was accompanied by an increase in pollen fertility. The appearance of aneuploid plants in each generation could be detected having various chromosomal abnormalities at meiosis. The frequency of hexaploid plants varied significantly among different cultivar combinations, from 0 to 56% in the H₄ generation, and it showed a positive correlation with pollen fertility. The frequency of SSR allelic fragments lost or novel alleles gained was significantly lower in H₄ than in H₂ and H₃, which reflects increasing genome stability in H₄. The A and C genomes were significantly less stable than the B genome, which may mainly result from frequent homoeologous pairing and rearrangements between the A and C genomes. Methods to establish a stable hexaploid Brassica crop by intercrossing these lines followed by intensive selection are also discussed.     

Cytoskeletal architecture and cathepsin B trafficking in human articular chondrocytes

In the differentiated state, human articular chondrocytes exhibited modestly developed cytoskeletal components, while cells dedifferentiated by serial subcultures in vitro displayed a prominent cytoskeleton. Morphological changes, a well-developed actin cytoskeleton, and the presence of numerous intracellular organelles were characteristic features of the dedifferentiated chondrocyte phenotype. These properties correlated with the expression, biosynthesis, storage, and secretion of the cysteine peptidase, cathepsin B, a marker of the dedifferentiated chondrocyte phenotype and a potent mediator of cartilage catabolism in osteoarthritis. Both the actin cytoskeleton and microtubules were responsible for trafficking of cathepsin B between cellular compartments in chondrocytes. Despite the endosomes and lysosomes storing high amounts of mature cathepsin B, this enzyme could not be visualized in its active form within these organelles. However, enzymatically active cathepsin B was associated with polymerized tubulin, and was no longer detectable after disruption of the microtubules. This enzyme species possibly represents the mature cathepsin B form in transport vesicles, after cleavage of the inhibitory propeptide, on the way to a final target. These results suggest noteworthy parallels between osteoarthritic articular cartilage and the artificially dedifferentiated cell phenotype, including the expression of type I collagen, the expression of cathepsin B, a significant modification of the cytoskeleton, and the formation of abundant secretory vesicles. These similarities justify the use of chondrocyte cultures as models of the behavior of cartilage cells in osteoarthritis.     

Efficient soybean transformation using hygromycin B selection in the cotyledonary-node method

The efficiency of soybean [Glycine max (L.) Merrill] transformation was significantly increased from an average of 0.7% to 16.4% by combining strategies to enhance Agrobacterium tumefaciens-mediated T-DNA delivery into cotyledonary-node cells with the development of a rapid, efficient selection protocol based on hygromycin B. Wounded cotyledonary-node explants were inoculated with A. tumefaciens carrying either a standard-binary or super-binary plasmid and co-cultivated in the presence of mixtures of the thiol compounds, L-cysteine, dithiothreitol, and sodium thiosulfate. Transformed shoots began elongating only 8 weeks after co-cultivation. Southern analysis confirmed integration of the T-DNA into genomic DNA and revealed no correlation between the complexity of the integration pattern and thiol treatment applied at co-cultivation. All T(0) plants were fertile and the majority of the lines transmitted the beta-glucuronidase (GUS) phenotype in 3:1 or 15:1 ratios to their progenies.     

Modeling Proximal Tubule Cell Homeostasis: Tracking Changes in Luminal Flow

During normal kidney function, there are routinely wide swings in proximal tubule fluid flow and proportional changes in Na⁺ reabsorption across tubule epithelial cells. This “glomerulotubular balance” occurs in the absence of any substantial change in cell volume, and is thus a challenge to coordinate luminal membrane solute entry with peritubular membrane solute exit. In this work, linear optimal control theory is applied to generate a configuration of regulated transporters that could achieve this result. A previously developed model of rat proximal tubule epithelium is linearized about a physiologic reference condition; the approximate linear system is recast as a dynamical system; and a Riccati equation is solved to yield the optimal linear feedback that stabilizes Na⁺ flux, cell volume, and cell pH. The first observation is that optimal feedback control is largely consigned to three physiologic variables, cell volume, cell electrical potential, and lateral intercellular hydrostatic pressure. Parameter modulation by cell volume stabilizes cell volume; parameter modulation by electrical potential or interspace pressure act to stabilize Na⁺ flux and cell pH. This feedback control is utilized in a tracking problem, in which reabsorptive Na⁺ flux varies over a factor of two, in order to represent a substantial excursion of glomerulotubular balance. The resulting control parameters consist of two terms, an autonomous term and a feedback term, and both terms include transporters on both luminal and peritubular cell membranes. Overall, the increase in Na⁺ flux is achieved with upregulation of luminal Na⁺/H⁺ exchange and Na⁺–glucose cotransport, with increased peritubular Na⁺–3HCO₃⁻ and K⁺–Cl⁻ cotransport, and with increased Na⁺, K⁺–ATPase activity. The configuration of activated transporters emerges as a testable hypothesis of the molecular basis for glomerulotubular balance. It is suggested that the autonomous control component at each cell membrane could represent the cytoskeletal effects of luminal flow.     

Antimicrobial Activities of Bacteriocins E 50–52 and B 602 Against Antibiotic-Resistant Strains Involved in Nosocomial Infections

The antimicrobial spectra of previously published bacteriocin E 50–52 (39 a.a.; 3,932 Da; pI = 8.5) and bacteriocin B 602 (29 a.a.; 3,864 Da; pI = 7.2) were determined. Named peptides were related to class IIa (pediocin-like) bacteriocins. Minimal inhibitory concentrations (MICs) of bacteriocins have been determined for bacterial isolates that were causative agents of nosocomial infections collected from Russian hospitals in 2003–2007, namely methicillin-resistant Staphylococcus aureus (MRSA) (n = 10); Acinetobacter baumannii (n = 11); Citrobacter freundii (n = 8); Escherichia coli (n = 9); Klebsiella pneumoniae (n = 10); Proteus spp. (n = 6); and Pseudomonas aeruginosa (n = 10). The majority of these tested isolates have been shown to be multidrug resistant and carry genetic determinants of antimicrobial resistance that were detected using polymerase chain reaction (PCR). The MICs of bacteriocin B 602 ranged from ≤0.025–1.56 μg/ml, and for bacteriocin E 50–52 from 0.05 to 6.25 μg/ml for all of 64 bacterial clinical isolates tested. Interestingly, the bacteriocins studied demonstrate activity on both Gram-positive and Gram-negative bacteria. Bacteriocins E 50–52 and B 602 show good activity against nosocomial bacterial agents resistant to many classes of modern antibacterials used in clinical practice. These bacteriocins should be examined as an alternative in treating infections caused by such agents.     

论四射珊瑚的内生长线——以新疆早二叠世 Kepingophyllum aksuense Wu et Zhou 为例

新疆早二叠世 Kepingophyllum aksuense Wu et Zhou的内生长线发育良好,它们是由年季节温度的变化而形成的.据内生长线,可推算出k. aksuense Wu et Zhou的平均生长率为5mm/年.运用珊瑚的生长率及年龄可计算出沉积事件发生的频率.     

Expression of a cholera toxin B subunit in transgenic lettuce (Lactuca sativa L.) using Agrobacterium-mediated transformation system

To increase expression level of cholera toxin B subunit (CTB) in lettuce plants, synthetic CTB (sCTB) gene based on the optimized codon usage was fused with an endoplasmic reticulum retention signal, KDEL. The sCTB gene was introduced into a plant expression vector and transformed to lettuce plants using Agrobacterium-mediated transformation system. As a selection marker, a bialaphos resistance (bar) gene that encodes phosphinothricin acetyltransferase (PAT), conferring tolerance to the herbicide phosphinothricin (PPT), was used. PCR amplification of genomic DNA confirmed the presence of the sCTB gene in the transgenic lettuce plants. Expressions of mRNA and protein of sCTB were observed by Northern and Western blot analyses, respectively. The sCTB synthesized in the transgenic lettuce showed strong affinity for GM₁-ganglioside suggesting that the sCTB conserved the antigenic sites for binding and proper folding of pentameric CTB structure. The expression level of CTB was relatively high, reaching total soluble protein (TSP) levels of 0.24% in transgenic lettuce.     

In Crystallo Selection to Establish New RNA Crystal Contacts

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Emplectopteridium alatum Kawasaki 的脉序*

Emplectopteridium alatum Kaw. 的脉序历来被描述为叶脉结网并具邻脉,主要基于具有邻脉这一特征,该种被归于美羊齿类.经笔者研究,这种植物没有邻脉而具伴网眼.这样,不但 E. alatum Kaw. 的分类位置需重新考虑,而且所谓 Emplectopteridium 演化系的基础也就完全瓦解.     

Insight into lymphoid development by gene expression profiling of avian B cells

The avian immune system provides an excellent model to track B-cell development from prebursal stem cells throughout B-cell differentiation and maturation. Bursal B cells are uniquely positioned at the crossroads of B-cell development, having properties of both stem cells and of mature B cells, as demonstrated by their ability to reconstruct the bursal B-cell compartment and to express and diversify the B-cell receptor at their cell surface. To understand avian B-cell development better, we determined the gene expression profile of different B-cell stages using a bursal expressed sequence tag array. The expression profile of bursal B cells reveals the presence of factors associated with B-cell signaling and defines novel B-cell-specific genes. Genes associated with proliferation, apoptosis, DNA repair and recombination are abundantly expressed. The expression profile of the DT40 cell line is most similar to bursal B cells rather than to other stages of B-cell development, confirming the suitability of DT40 for studies of B-cell physiology. Interestingly, prebursal stem cells express genes involved in B-cell receptor signaling, although they express only low levels of immunoglobulin genes. This suggests that B-cell receptor-mediated selection is present before bursal colonization. The gene expression signatures of germinal centers and cells of the Harderian gland indicate that evolutionarily conserved genetic programs regulate B-cell activation and terminal differentiation.Electronic Supplementary Material Supplementary material is available in the online version of this article atK. Koskela, P. Kohonen and P. Nieminen contributed equally to this work     

Human parvovirus B19 virus-like particles: In vitro assembly and stability

Virus-like particles (VLPs) are biological nanoparticles identical to the natural virions, but without genetic material. VLPs are suitable for the analysis of viral infection mechanisms, vaccine production, tissue-specific drug delivery, and as biological nanomaterials. Human parvovirus B19 (B19) infects humans; therefore VLPs derived from this virus have enormous potential in medicine and diagnostics. Current production of self-assembled VLPs derived from B19 is typically carried out in eukaryotic expression systems. However many applications of VLPs require access to its internal core. Consequently, the processes of disassembly and further reassembly of VLPs are critical both for purification of viral proteins, and for encapsulation purposes. Herein we report the in vitro self-assembly of B19 VLPs derived from the recombinant VP2 protein expressed in Escherichia coli and the effects of pH and ionic strength on the assembly process. Our results demonstrate that VP2 is able to form VLPs completely in vitro. At neutral pH, homogeneous VLPs assemble, while at acidic and basic pHs, with low ionic strength, the major assemblies are small intermediates. The in vitro self-assembled VLPs are highly stable at 37 °C, and a significant fraction of particles remain assembled after 30 min at 80 °C.     

论双壳类的 Pteroperna 及其模式种 Pteroperna costatula (Deslongchamps)

翼股蛤(Pteroperna)是 J.Morris 和 J.Lycett 于1853年建立,但该属的分类位置当时并不明确,仅仅在讨论中提到可能为 Pterinea的亚属。Cox(1940)讨论 Pteroperna 时则将其作为翼蛤科(Pteriidae)的属而沿用至今。笔者于1984年在唐古拉山雁石坪地区测制侏罗纪地层剖面时,在同一层位中采集到许多隶属于 Pteroperna costatula 的标本,它们的壳饰特征、壳体形状和英国侏罗纪大鲕状灰岩(Great O(?)lite)中产出的同种标本几无差异。标本大多保存良好,特别是它们的壳层和其围岩在弱酸中可产生差异溶蚀,利用酸蚀法可得到许多暴露出铰系构造和软体印痕的标本,其中有一些反映出个体发育各个阶段的生长特     

The Final Size of an Epidemic and Its Relation to the Basic Reproduction Number

We study the final size equation for an epidemic in a subdivided population with general mixing patterns among subgroups. The equation is determined by a matrix with the same spectrum as the next generation matrix and it exhibits a threshold controlled by the common dominant eigenvalue, the basic reproduction number R₀{\mathcal{R}_{0}}: There is a unique positive solution giving the size of the epidemic if and only if R₀{\mathcal{R}_{0}} exceeds unity. When mixing heterogeneities arise only from variation in contact rates and proportionate mixing, the final size of the epidemic in a heterogeneously mixing population is always smaller than that in a homogeneously mixing population with the same basic reproduction number R₀{\mathcal{R}_{0}}. For other mixing patterns, the relation may be reversed.     

Brachyspira asperella Yu et Zhang的个体发育

对Brachyspira asperella Yu et Zhang的40个个体的测量统计表明,此种在生长发育过程中可以区分出3个生长阶段:幼年期壳体生长速度缓慢,壳形卵圆形,胎壳乳突状,壳口圆形;成年期生长迅速,壳高显著大于壳宽的增长率,壳形卵圆形-长卵圆形,壳口卵圆形;老年期生长速度缓慢,壳形长卵圆形,壳饰强烈。这3个生长期代表了此种的个体发育过程。研究化石腹足类种的个体发育过程不仅能了解这一类群的系统发生史、生物演化过程及生物间的亲缘关系,而且能提高物种研究程度,避免分类上的错误。     

Degeneracy-Driven Self-Structuring Dynamics in Selective Repertoires

Numerous biological interactions, such as interactions between T cell receptors or antibodies with antigens, interactions between enzymes and substrates, or interactions between predators and prey are often not strictly specific. In such less specific, or “sloppy,” systems, referred to here as degenerate systems, a given unit of a diverse resource (antigens, enzymatic substrates, prey) is at risk of being recognized and consumed by multiple consumers (lymphocytes, enzymes, predators). In this study, we model generalized degenerate consumer-resource systems of Lotka–Volterra and Verhulst types. In the degenerate systems of Lotka–Volterra, there is a continuum of types of consumer and resource based on variation of a single trait (characteristic, or preference). The consumers experience competition for a continuum of resource types. This non-local interaction system is modeled with partial differential-integral equations and shows spontaneous self-structuring of the consumer population that depends on the degree of interaction degeneracy between resource and consumer, but does not mirror the distribution of resource. We also show that the classical Verhulst (i.e. logistic) single population model can be generalized to a degenerate model, which shows qualitative behavior similar to that in the degenerate Lotka–Volterra model. These results provide better insight into the dynamics of selective systems in biology, suggesting that adaptation of degenerate repertoires is not a simple “mirroring” of the environment by the “fittest” elements of population.