微小花蝽对温室白粉虱的捕食作用

研究微小花蝽Orius minutus(L.)对温室白粉虱Trialeurodes vaporariorum(Westwood)的捕食作用。结果表明,微小花蝽成虫对温室白粉虱各虫态的功能反应呈HollingⅡ型。微小花蝽成虫对温室白粉虱卵、1龄和2龄混合若虫及其3龄若虫的理论最大捕食量分别为123,74和52头/d。微小花蝽成虫对温室白粉虱卵的捕食效应随捕食者个体间干扰作用的增加而下降,符合Hassel-Varley方程,捕食作用率(E)随着微小花蝽数(P)增加而呈幂指数下降,模拟模型E=0.1021P-0.3189,干扰系数为0.3189。在15～40℃的温度范围内,随着温度的升高微小花蝽成虫对温室白粉虱卵的寻找效率提高,最高达1.1990,处置时间缩短,最低达到0.0035d。     

The effects of spacer sequences on silencing efficiency of plant RNAi vectors

RNA interference (RNAi) has been used to suppress gene expression in various eukaryotic organisms. In plants, RNAi can be induced by introduction of an RNAi vector that transcribes a self-complementary hairpin RNA. Most basic RNAi constructs have an inverted repeat interrupted with a spacer sequence. To test silencing capability of RNAi constructs, we developed an in vivo assay that is based on the RNAi-mediated changes of the α-linolenic acid content in hairy roots. A tobacco endoplasmic reticulum ω-3 fatty acid desaturase (NtFAD3) is the main enzyme for production of α-linolenic acid of root membrane lipids. Tobacco hairy roots transformed with the RNAi vectors against the NtFAD3 gene showed a decrease in α-linolenic acid content. The frequency of RNA silencing was more affected by spacer sequence than by spacer length, at least between 100 and 1800 bp. Since significant amounts of hairpin RNA against the NtFAD3 gene remained in the transgenic plants displaying a weak silencing phenotype, low degree of silencing was attributed to low efficiency of hairpin RNA processing mediated by Dicer-like proteins. Our results show the possibility of producing a broad range of the RNAi-induced silencing phenotypes by replacing the spacer sequence of RNAi construct.     

Breeding success and population trends in Adélie penguins in areas with low and high levels of human disturbance

The breeding performance and population trends of Adélie penguins (Pygoscelis adeliae) was studied at Esperanza/Hope Bay, Antarctic Peninsula, by comparing an area with low levels of human disturbance (LLD) and an area with high levels of human disturbance (HLD), close to an Argentine research station. From 1995/1996 to 2004/2005 (except for 1999/2000 and 2003/2004), the following population parameters were measured in both areas: (1) the number of breeding pairs, (2) the number of chicks in creches and (3) the number of chicks produced by breeding pairs. Counts were made for 26 breeding groups situated in the LLD area and 63 breeding groups located in the HLD area. The number of chicks per breeding pair was obtaobtained by following 100 marked nests in each area. All parameters were measured as described in the CCAMLR Monitoring Program protocols. The magnitude and direction (increasing or decreasing) of the changes in breeding population size and the number of chicks creched were similar in both areas. Overall, the number of breeding pairs decreased from 4,744 to 2,968 (37.4%) in the LLD area, and from 8,744 to 5,378 (38.6%) in the HLD area. The number of chicks fledged increased from 3,808 to 4,065 (6.7%) in the LLD area, and decreased from 6,991 to 6,712 (4%) in the HLD area. Breeding success (chicks fledged per marked nest) did not differ significantly between areas for most of the seasons compared. In 1996/1997, breeding success was significantly higher in the HLD area. Our data suggest that environmental influences currently exert greater effects than human disturbance on the penguin population at Esperanza Bay.     

Non-fucosylated therapeutic antibodies: the next generation of therapeutic antibodies

Therapeutic antibody IgG1 has two N-linked oligosaccharide chains bound to the Fc region. The oligosaccharides are of the complex biantennary type, composed of a trimannosyl core structure with the presence or absence of core fucose, bisecting N-acetylglucosamine (GlcNAc), galactose, and terminal sialic acid, which gives rise to structural heterogeneity. Both human serum IgG and therapeutic antibodies are well known to be heavily fucosylated. Recently, antibody-dependent cellular cytotoxicity (ADCC), a lytic attack on antibody-targeted cells, has been found to be one of the critical effector functions responsible for the clinical efficacy of therapeutic antibodies such as anti-CD20 IgG1 rituximab (Rituxan^®) and anti-Her2/neu IgG1 trastuzumab (Herceptin^®). ADCC is triggered upon the binding of lymphocyte receptors (FcγRs) to the antibody Fc region. The activity is dependent on the amount of fucose attached to the innermost GlcNAc of N-linked Fc oligosaccharide via an α-1,6-linkage, and is dramatically enhanced by a reduction in fucose. Non-fucosylated therapeutic antibodies show more potent efficacy than their fucosylated counterparts both in vitro and in vivo, and are not likely to be immunogenic because their carbohydrate structures are a normal component of natural human serum IgG. Thus, the application of non-fucosylated antibodies is expected to be a powerful and elegant approach to the design of the next generation therapeutic antibodies with improved efficacy. In this review, we discuss the importance of the oligosaccharides attached to the Fc region of therapeutic antibodies, especially regarding the inhibitory effect of fucosylated therapeutic antibodies on the efficacy of non-fucosylated counterparts in one medical agent. The impact of completely non-fucosylated therapeutic antibodies on therapeutic fields will be also discussed.     

In situ observation of a cell adhesion and metabolism using surface infrared spectroscopy

In this study, we report on an in situ monitoring system of living cultured cells using infrared absorption spectroscopy in the geometry of multiple internal reflections (MIR-IRAS). In order to observe living cultured cells, the temperature in the sample chamber of a FT-IR spectrometer was maintained at 37 °C and a humidified gas mixture containing 5% CO₂ was introduced into the sample chamber. Human breast cell line MCF-7 cultured on Si MIR prisms were placed in the sample chamber and infrared spectra of MCF-7 cells were collected for 5 h. It was found that the adhesion and metabolism of MCF-7 cells could be monitored by the absorption intensity of amide-II protein band (1,545 cm⁻¹) and also by the absorption intensities of CH _x bands (2,700–3,100 cm⁻¹). These results suggest that our system is useful for a nondestructive and non-label monitoring of cell viability. Our method based on infrared absorption spectroscopy has a potential for bioscreening application.     

Recent advances in the generation of human monoclonal antibody

The use of monoclonal antibodies (mAbs) has now gained a niche as an epochal breakthrough in medicine. Engineered antibodies (Abs) currently account for over 30% of biopharmaceuticals in clinical trials. Several methods to generate human mAbs have evolved, such as (1) immortalization of antigen-specific human B cell hybridoma technology, (2) generation of chimeric and humanized antibody (Ab) from mouse Ab by genetic engineering, (3) acquisition of antigen-specific human B cells by the phage display method, and (4) development of transgenic mice for producing human mAbs. Besides these technologies, we have independently developed a method to generate human mAbs by combining the method of in vitro immunization using peripheral blood mononuclear cells and the phage display method. In this paper, we review the developments in these technologies for generating human mAbs.     

Human urine is an excellent liquid waste for the culture of fish food organism, Moina micrura

With a view to converting human urine into bio-wealth in the form of zooplankton, the nutrient potentials of liquid wastes (0.11 mL L⁻¹)—(i) human urine (♂), (ii) cow urine, (iii) human–cow mixed urine or some solid wastes (0.11 g L⁻¹): (iv) vermi-compost, (v) cow dung, (vi) poultry droppings and (vii) mixed wastes (vermi-cow-poultry)—were evaluated for the mass culture of zooplankton Moina micrura in 24 outdoor tanks (4500 L) in triplicate treatments using life table as indicator during the period of October–December, 2005. Neonates of Moina micrura held in the treatment with human urine started reproduction at least 4 days earlier than other solid wastes tested. Total number of Moina micrura enumerated in the culture tank, related with offspring production per life span, was maximum in case of human urine treatment, followed by human–cow mixed urine, cow urine, vermin-compost, poultry droppings, mixed wastes (vermin–cow–poultry), cow dung and control treatments. The relationship between the total offspring production per female per life span and the nitrogen content of water in different treatments implied that human urine was an excellent liquid waste that can be used for the mass production of zooplankton Moina micrura required for larval and post larval rearing of commercial fishes.     

Mechanisms of seizure propagation in a cortical model

We consider a mathematical model of mesoscopic human cortical ictal electrical activity. We compare the model results with ictal electrocortical data recorded from three human subjects and show how the two agree. We determine that, in the model system, seizures result from increased connectivity between excitatory and inhibitory cell populations, or from decreased connectivity within either excitatory or inhibitory cell populations. We compare the model results with the disinhibition and 4-AP models of epilepsy and suggest how the model may guide the development of new anticonvulsant therapies.     

An extract of Pelargonium sidoides (EPs 7630) inhibits in situ adhesion of Helicobacter pylori to human stomach

Root extract from Pelargonium sidoides DC is used therapeutically as antimicrobial agent against infections of the respiratory system. In order to elucidate possible modes of actions we investigated the influence of P. sidoides root extract on microbial adhesion with Helicobacter pylori as model microorganism, a germ with a strong adherence to human stomach tissue. In an in-situ anti-adhesion assay intact human stomach tissue from patient resectates was incubated with fluorescent-labelled bacteria. Epithelial adhesion occurred in untreated samples and was quantified by fluorescent microscopy. Pre-treatment of the bacteria with Pelargonium extract showed good anti-adhesive activity. The antiadhesive effect was clearly dose-dependent in a range from 0.001 to 10 mg/ml. Within agar diffusion-test the extract had no direct cytotoxicity against H. pylori. The results show that the root extract from Pelargonium sidoides is a potent anti-adhesive agent against H. pylori and could therefore be a useful choice to avoid the first step of a bacterial infection.     

Fetal and early post-natal development of the human spleen: from primordial arterial B cell lobules to a non-segmented organ

Immunohistological analysis of 31 human spleens from the 11th week of gestation to the early postnatal period suggested that fetal organ development may be preliminarily divided into four stages. At stage 0 the organ anlage contained erythrocyte precursors, few macrophages and almost no lymphocytes. Fetal spleens of stage I exhibited arterial vascular lobules and lymphocytes just began colonizing the organ. At stage II, B and T lymphocytes formed periarteriolar clusters. B cell clusters predominated, because B cells aggregated around the more peripheral branches of splenic arterioles, while T cells occupied the more centrally located parts of the vessels. The vascular lobules of stage I and II consisted of central arterioles surrounded by B cells, capillaries and peripheral venules. The lobular architecture slowly dissolved at late stage II when sinuses grew out from the peripheral venules into the centre of the lobule. Interestingly, the B cell accumulations around peripheral arterioles did not represent the precursors of follicles, but apparently persisted as periarteriolar B cell clusters in the adult splenic red pulp, while follicles containing FDCs developed at late stage II from B cells in direct contact to T cell clusters around larger arterial vessels. At stage III before birth the lobular architecture was no longer recognized. The chemokine CXCL13 was already present in vascular smooth muscle and adjacent stromal cells at stage I before B cells immigrated. CCL21, on the contrary, was only demonstrated in fibroblast-like cells supporting T cell clusters from stage II onwards.