On the origin of Metazoan adhesion receptors: cloning of integrin alpha subunit from the sponge Geodia cydonium

Integrins are prominent receptors known from vertebrates and the higher phyla of invertebrates. Until now, no evidence has been provided for the existence of integrins in the lowest Metazoa, the sponges (Porifera). We have isolated and characterized a cDNA clone encoding the alpha subunit of integrin from the marine sponge Geodia cydonium (GCINTEG). The open reading frame encodes a polypeptide of 1,086 residues (118 kDa). The intracellular domain features the sequence Tyr- Phe-x-Gly-Phe-Phe-x-Arg, which is different in one residue from the characteristic consensus pattern for integrin alpha subunits. We conclude that sponges, the oldest multicellular animal phylum, already utilize the structural elements which are required for a tuned and controlled interaction among cells, and between cells and the extracellular matrix.      

In vitro shoot proliferation and production of sets from garlic and shallot

A procedure is described to regenerate shoots and bulbs in vitro with high frequency from shoot tips of garlic and shallot plants using benzyladenine or thidiazuron. Regenerated shoots were induced to form bulbs in Murashige and Skoog medium (1962) containing 5 g l^-1 activated charcoal and 120 g l^-1 sucrose under a long-day photoperiod. Bulbs formed in vitro were transferred to soil without acclimatization and produced viable plants. This method could be useful to produce low-cost bulbs, which are easy to handle and store until needed.Abbreviations AC activated charcoal - BA benzyladenine - IBA indolebutyric acid - MS Murashige & Skoog's (1962) medium - NAA naphthaleneacetic acid - TDZ thidiazuron     

In vitro bulb production fromAllium spp.

Summary A procedure for bulb formation from onion, garlic, and shallot explants is described. Explants from cut stem bases were cultured in shoot induction medium composed of Murashige and Skoog (MS) medium with or without N⁶-benzyladenine. Shoots produced were then transferred to bulb induction medium composed of MS medium containing 5 g/liter activated charcoal and 120 g/liter sucrose under a long-day photoperiod and 28° C. Bulbs were also produced from onion and garlic directly, without passing through shoot formation, when explants were cultured in the bulb induction medium described above. Bulbs were transferred to soil without acclimatization and produced viable plants.     

流感病毒的检测和分型技术研究进展

近年来,病毒性流感的不断流行和暴发已引起世界范围的广泛关注。为了更好地对流感病毒进行检测和分型,我们对目前流感病毒常用的血清学检测和分型方法、免疫荧光法、PCR方法、多重RT-PCR法、实时RT-PCR法、依赖核酸序列的扩增法、环介导等温扩增法、焦磷酸测序法、基因芯片技术分别进行了描述,并阐述了其优缺点。     

The role of seed coats in seed viability

The seed coat is the seed’s primary defense against adverse environmental conditions. A hard seed coat protects the seed not only from mechanical stress but also from microorganism invasion and from temperature and humidity fluctuations during storage. Phenolic compounds in the seed coat contribute to seed hardness and inhibition of microorganism growth. During germination, the seed coat protects the seed from hydration stress and electrolyte leakage.     

Microbial Transport, Survival, and Succession in a Sequence of Buried Sediments

Abstract Two chronosequences of unsaturated, buried loess sediments, ranging in age from <10,000 years to >1 million years, were investigated to reconstruct patterns of microbial ecological succession that have occurred since sediment burial. The relative importance of microbial transport and survival to succession was inferred from sediment ages, porewater ages, patterns of abundance (measured by direct counts, counts of culturable cells, and total phospholipid fatty acids), activities (measured by radiotracer and enzyme assays), and community composition (measured by phospholipid fatty acid patterns and Biolog substrate usage). Core samples were collected at two sites 40 km apart in the Palouse region of eastern Washington State, near the towns of Washtucna and Winona. The Washtucna site was flooded multiple times during the Pleistocene by glacial outburst floods; the Winona site elevation is above flood stage. Sediments at the Washtucna site were collected from near surface to 14.9 m depth, where the sediment age was approximately 250 ka and the porewater age was 3700 years; sample intervals at the Winona site ranged from near surface to 38 m (sediment age: approximately 1 Ma; porewater age: 1200 years). Microbial abundance and activities declined with depth at both sites; however, even the deepest, oldest sediments showed evidence of viable microorganisms. Same-age sediments had equal quantities of microorganisms, but different community types. Differences in community makeup between the two sites can be attributed to differences in groundwater recharge and paleoflooding. Estimates of the microbial community age can be constrained by porewater and sediment ages. In the shallower sediments (<9 m at Washtucna, <12 m at Winona), the microbial communities are likely similar in age to the groundwater; thus, microbial succession has been influenced by recent transport of microorganisms from the surface. In the deeper sediments, the populations may be considerably older than the porewater ages, since microbial transport is severely restricted in unsaturated sediments. This is particularly true at the Winona site, which was never flooded.     

Sulfation of fucoidin in focus embryos: III. Required for localization in the rhizoid wall

Zygotes of the brown alga Fucus distichus L. Powell accumulate a sulfated polysaccharide (fucoidin) in the cell wall at the site of rhizoid formation. Previous work indicated that zygotes grown in seawater minus sulfate do not sulfate the preformed fucan (an unsulfated fucoidin) but form rhizoids. Under these conditions, we determined whether sulfation of the fucan is required for its localization in the rhizoid wall. This was accomplished by developing a specific stain for both the fucan and fucoidin. Using a precipitin assay, we demonstrated in vitro that the lectin ricin (RCA(I)) specifically complexes with both the sulfated and desulfated polysaccharide. No precipitate is observed when either is incubated in 0.1 M D-galactose or when RCA(I) is mixed with laminarin or alginic acid, the other major polysaccharides in Fucus. RCA(I) conjugated with fluorescein isothiocyanate (FITC) is also shown to bind specifically to fucoidin using a filter paper (DE81) assay. When added to zygotes, RCA(I)-FITC binds only to the site of fucoidin localization, i.e., the rhizoid cell wall. However, RCA(I)-FITC is not observed in the rhizoid wall of zygotes grown in the absence of sulfate. This observation is not due to inability of RCA(I)-FITC to bind to the fucan in vivo. Chemically desulfated cell walls that contained fucoidin in the rhizoid wall bind RCA(I)-FITC only in the rhizoid region. Also, the concentration of fucose-containing polymers and polysaccharides that form precipitates with RCA(I) is the same in embryos grown in the presence or absence of sulfate. If sulfate is added back to cultures of zygotes grown without sulfate, fucoidin is detected at the rhizoid tip by RCA(I)-FITC several hours later. These results support the conclusion that the enzymatic sulfation of the fucan is a modification of the polysaccharide required for its localization and/or assembly into a specific region of the cell wall.     

Numerical Taxonomy of Gram-Positive and Catalase-Positive Rods Isolated from Frozen Vegetables

One hundred isolates from peas, beans, and corn were compared with cultures of Corynebacterium, Microbacterium, and Arthrobacter by use of numerical taxonomic procedures. Six groups (clusters), representing 75% of the isolates, resembled Corynebacteriaceae. There was some doubt regarding the genera represented because the groups were not closely related to many of the known strains. The relationship of the different groups to each other, as well as a number of their properties, is presented.     

In vitro shoot proliferation and plant regeneration from kurrat (Allium ampeloprasum var. kurrat) seedlings

Shoots were produced from kurrat seedling and mature plant explants cultured in Murashige and Skoog medium (MS) alone or supplemented with 4.4 M benzyladenine (BA). Shoots were also produced from explants through a two-step procedure. Regenerated shoots were induced to form roots on MS medium with 5 g I^-1 activated charcoal. Plants were successfully established in soil.Abbreviations AC activated charcoal - BA benzyladenine - MS Murashige & Skoog's (1962) medium - 2,4-d 2,4-dichlorophenoxyacetic acid