Functional analysis of Abp1 in Dictyostelium

textThis work identified an ortholog of Abp1 (actin binding protein 1) in Dictyostelium (Dabp1). In order to analyze the functions of Dabp1 in Dictyostelium, loss-of–function studies and gain-of-function studies were performed by generating cells that either deleted the Dabp1 gene from the genome or overexpressed the Dabp1 protein. In these mutants, most actin-based processes were intact. However, cell motility was altered during early development. During chemotactic streaming, more than 90% of wild type cells had a single leading pseudopodium and a single uropod, whereas more than 27% of Dabp1 null cells projected multiple pseudopodia. Similarly, ~ 90% of cells that overexpressed Dabp1 projected multiple pseudopodia during chemotactic streaming, and displayed reduced rates of cell movement. Expression of the SH3 domain of Dabp1 showed this domain to be an important determinant in regulating pseudopodium number. These results suggest that Abp1 controls pseudopodium number and motility in early stages of chemotactic aggregation in Dictyostelium. This work also revealed an interplay between Dabp1 and MyoB, one of the Myosin I proteins, in controlling pseudopodia formation in Dictyostelium. These two proteins colocalize partially at the cortex in growing cells. The peripheral localization of MyoB was dependent on Dabp1. Depletion of both Dabp1 and MyoB caused defects in organization of the actin cytoskeleton and actin related activities such as formation of small F-actin filled spikes on the cell cortex of growing cells, a higher percentage of multinucleated cells, and an increased number of pseudopodia branching extensively. When MyoB was overexpressed in Dabp1 null mutants, cells had similar phenotypes as Dabp1/MyoB double null mutants, and displayed an increased number of pseudopodia with many branches. Overexpression of Dabp1 in MyoB null mutants rescued the defects in pseudopodia formation. The SH3 of Dabp1 was shown to be important for the rescue of defects caused by depletion of MyoB. Collectively, these data suggest that MyoB and Dabp1 work cooperatively to regulate the uniformity and integrity of the actin extensions during chemotaxis. MyoB requires Dabp1 to function in this process. Dabp1 may function as a scaffold to recruit MyoB to the proper localization. These studies of Dabp1 in Dictyostelium raise broad question about functions of actinassociated proteins in pseudopodia formation and the importance of uniformity and integrity for actin structures in chemotaxis.Microbiolog

Bar-induced central star formation as revealed by integral field spectroscopy from CALIFA

We investigate the recent star formation history (SFH) in the inner region of 57 nearly face-on spiral galaxies selected from the Calar Alto Legacy Integral Field Area (CALIFA) survey. For each galaxy we use the integral field spectroscopy from CALIFA to obtain two-dimensional maps and radial profiles of three parameters that are sensitive indicators of the recent SFH: the 4000\AA\ break (D$_n$(4000)), and the equivalent width of H$\delta$ absorption (EW(H$\delta_A$)) and H$\alpha$ emission (EW(H$\alpha$)). We have also performed photometric decomposition of bulge/bar/disk components based on SDSS optical image. We identify a class of 17 "turnover" galaxies whose central region present significant drop in D$_n$(4000), and most of them correspondingly show a central upturn in EW(H$\delta_A$) and EW(H$\alpha$). This indicates that the central region of the turnover galaxies has experienced star formation in the past 1-2 Gyr, which makes the bulge younger and more star-forming than surrounding regions. We find almost all (15/17) the turnover galaxies are barred, while only half of the barred galaxies in our sample (15/32) are classified as a turnover galaxy. This finding provides strong evidence in support of the theoretical expectation that the bar may drive gas from the disc inward to trigger star formation in galaxy center, an important channel for the growth/rejuvenation of pseudobulges in disc galaxies.Comment: 19 pages, 10 figures, ApJ accepte

Dynamics in a delayed diffusive cell cycle model

In this paper, we construct a delayed diffusive model to explore the spatial dynamics of cell cycle in G2/M transition. We first obtain the local stability of the unique positive equilibrium for this model, which is irrelevant to the diffusion. Then, through investigating the delay-induced Hopf bifurcation in this model, we establish the existence of spatially homogeneous and inhomogeneous bifurcating periodic solutions. Applying the normal form and center manifold theorem of functional partial differential equations, we also determine the stability and direction of these bifurcating periodic solutions. Finally, numerical simulations are presented to validate our theoretical results

Study on Soybean Resistance to Aphids

Soybean is the principal oil-producing crop in Liaoning Province and northeast of China. Soybean aphid (Aphis Glycines Matsmura) is a common insect pest and occurs almost every year. Aphid damage causes shrinking of young leaves, hampering of roots, dwarfing of stems and leaves, and reduction of pod and kernel numbers in the soybean plant. More than half of yield is lost in a severely damaged field. It is becoming one of the most important constraints to stable and high soybean yield. At present, spraying chemical insecticide is the major method for aphid control. Although it has taken effect, it requires numerous manpower, material and financial resources every year. Furthermore, it causes environmental pollution, is poisonous to people and animals, and injurious to natural enemies of soybean aphid. Pest resistance to constantly used chemical pesticides will reduce control efficiency and will cause an outbreak of pests again. In 1951, Painter, an American scientist, suggested the theory of plant resistance to insect pests after analyzing a large amount of research data, and he aroused the interest of scientists in different countries. Selection and breeding for plant resistance to insects have become basic modes of integrated pest control presently and for the future. From 1979 to 1985, Guo et al. successfully identified the resistance of soybeans to aphids and obtained a quantity of source material. On the basis of that work, this study on plant resistance to aphids was developed.Originating text in Chinese.Citation: He, Fugang, Liu, Xiaodong, Yan, Fanyue, Wang, Yanqin. (1995). Study on Soybean Resistance to Aphids. Liaoning Agricultural Science, 4, 30-34

Apoptotic effect of selenium mushroom extract from Qinba on multiple myeloma cells

Qinba selenium mushroom is a mushroom belonging to the Basidiomycetes family, which is believed to have anti- oxidant, anti-tumoral and antimutagenic activities. However, the efficacy of Qinba selenium mushroom against multiple myeloma has not been confirmed. The present study aimed to investigate the apoptotic effect of FA-2-b-β, the selenium mushroom extract from Qinba on multiple myeloma (MM) cells. The MM RPMI-8226 cells were treated with FA-2-b-β at different concentrations and time points. MM RPMI8226 cell proliferation and apoptosis were detected by the Cell Counting Kit-8 (CCK-8) assay and Annexin V/propidium iodide (PI) assay, RT-QPCR and western blotting analyses were performed to determine the proteins and pathways involved. The results of the present study demonstrated that FA-2-b-β has high antiproliferative activities and strong pro-apoptotic effects on MM RPMI-8226 cells, and its pharmacological effects on proliferation changes occurred in a dose- and time-dependent manner. In addition, we found that FA2-b-β was able to induce cell apoptosis and promote cell cycle arrest at G0/G1 phase. In summary, the results illustrate the involvement of FA-2-b-β in mediating G0/G1 cell cycle arrest and apoptosis in MM RPMI8226 cells, which suggested that FA-2-b-β might have therapeutic potential against multiple myeloma as an effective compound, and may provide useful information for the development of a novel therapeutic target in this area

Mesoporous iron-titania catalyst for cyclohexane oxidation

This is the first report of using ultrasound radiation for depositing a nanosized catalyst (iron oxide) into the pores of a mesoporous material (titania); the resulting catalyst is used for the oxidation of cyclohexane under mild conditions

MicroRNA-184 downregulates nuclear receptor corepressor 2 in mouse spermatogenesis

<p>Abstract</p> <p>Background</p> <p>There have been increasing attentions on the role of small RNAs, especially microRNAs in post-transcriptional gene regulation during spermatogenesis. MicroRNA-184 (miR-184) has been shown to be mainly expressed in the testis and brain, and that its expression levels are by far the highest in the testis. However, the role of miR-184 in mammalian spermatogenesis remains unclear.</p> <p>Results</p> <p>In this study, we demonstrated that miR-184 levels were increased during mouse postnatal testis development. Specifically, miR-184 expression was restricted to the germ cells from spermatogonia to round spermatids. Overexpression of miR-184 promoted the proliferation of a germ cell line, GC-1spg. Moreover, miR-184 downregulated <it>nuclear receptor corepressor 2 </it>(<it>Ncor2</it>) by targeting its 3' untranslated region through inhibiting NCOR2 protein translation.</p> <p>Conclusions</p> <p>MiR-184 may be involved in the post-transcription regulation of mRNAs such as <it>Ncor2 </it>in mammalian spermatogenesis.</p

Optimum Spraying Time and Management Guidelines for Soybean Aphid Control

In Liaoning Province, the population of soybean aphid, Aphis glycines Matsumura, increases the most rapidly in late June, which is the critical period for aphid control. The current guideline for spraying is 10,000 aphids per100 plants. This guideline may be relaxed to 23,800 - 40,700 for cultivar Tiefeng #18 and to 26,500 – 33,000 for cultivar Liaodou #3 in the plains region found in the middle and lower reaches of Liaohe River. It is difficult to use aphid numbers as a management guideline in agricultural practice. According to our studies, the ratio of infested plants with rolled leaves is closely correlated to the aphid number per 100 plants. The linear regression equation is ? = 4.283 + 1.8419x (r = 0.90), where ? is the rolled leaf ratio and x is the aphid numbers per 100 plants. Therefore, instead of aphid numbers per 100 plants, we propose to use the ratio of plants with rolled leaves as the management guideline for large-scale field control of soybean aphids, which is 10% for Tiefeng #18 and 8% for Liaodou #3.Originating text in Chinese.Citation: He, Fugang, Yan, Fanyyue, Xin, Wanmin, Lii, Xiaoping, Wang, Yanqin, Zhang, Guangxue. (1991). Optimum Spraying Time and Management Guidelines for Soybean Aphid Control. Acta Phytophylacica Sinica, 18(2), 155-159

Characterization of isoprene-derived secondary organic aerosols at a rural site in North China Plain with implications for anthropogenic pollution effects

Isoprene is the most abundant non-methane volatile organic compound (VOC) and the largest contributor to secondary organic aerosol (SOA) burden on a global scale. In order to examine the influence of high concentrations of anthropogenic pollutants on isoprene-derived SOA (SOA(i)) formation, summertime PM2.5 filter samples were collected with a three-hour sampling interval at a rural site in the North China Plain (NCP), and determined for SOA(i) tracers and other chemical species. RO2+NO pathway derived 2-methylglyceric acid presented a relatively higher contribution to the SOA, due to the high-NOx (similar to 20 ppb) conditions in the NCP that suppressed the reactive uptake of RO2+HO2 reaction derived isoprene epoxydiols. Compared to particle acidity and water content, sulfate plays a dominant role in the heterogeneous formation process of SOA(i). Diurnal variation and correlation of 2-methyltetrols with ozone suggested an important effect of isoprene ozonolysis on SOA(i) formation. SOA(i) increased linearly with levoglucosan during June 10-18, which can be attributed to an increasing emission of isoprene caused by the field burning of wheat straw and a favorable aqueous SOA formation during the aging process of the biomass burning plume. Our results suggested that isoprene oxidation is highly influenced by intensive anthropogenic activities in the NCP