Distinct lipoxygenase species appear in the hypocotyl/radicle of germinating soybean

Three lipoxygenase isozymes are synthesized in developing soybean (Glycine max [L.] Merr. cv Williams) embryos and are found in high levels in cotyledons of mature seeds (B Axelrod, TM Cheesbrough, S Zimmer [1981] Methods Enzymol 71: 441-451). Upon germination at least two new protein species appear which are localized mainly (on a protein basis) in the hypocotyl/radicle section. These lipoxygenase species appear also in seedlings of each of three lipoxygenase nulls (1×1, 1×2, and 1×3) deficient in one of the dormant seed lipoxygenases. The germination-associated species are distinguishable from dry seed lipoxygenase by their more acidic isoelectric points as revealed in isoelectric focusing gels. They are active from as early as 2 to at least 5 days after the start of imbibition. These germination-stimulated species qualify as lipoxygenase by their inhibition by the lipoxygenase inhibitors n-propyl gallate and salicyl hydroxamic acid and their lack of inhibition by KCN. Further, they are not active on the peroxidase substrate pair H₂O₂/3-amino-9-ethyl carbazole. They are recognized on Western blots by polyclonal antibodies to the seed lipoxygenase-1 isozyme and the major induced species has a molecular weight of approximately 100,000, similar to that of the cotyledon lipoxygenases. These lipoxygenases appear to be synthesized de novo upon germination since they comigrate with radioactive protein species from seeds germinated in [³⁵S]methionine.     

普通小麦栽培品种丰抗13的4B—1D染色体易位的鉴定

通过细胞学观察,在普通小麦栽培品种“丰抗13”和“京红1号”的杂交后代中,发现有多价体出现,这就表明有染色体易位发生。为进一步弄清究竟是哪条染色体发生了易位,我们采用单体测交方法,观察鉴定所有各单体系F_1的花粉母细胞第一次减数分裂中期Ⅰ(以下简称PMCs中Ⅰ)染色体构型。从鉴定结果发现,凡2n=42的F_1 PMCs中Ⅰ出现19~Ⅱ 1~Ⅳ,而2n=41的F_1PMCs中Ⅰ的染色体构型不同,单体与易位有关的两个单体系4B和1D F_1 PMCs中的Ⅰ构型中有部分呈现为19个二价体加1个三价体,即19~Ⅱ 1~Ⅲ,没有单价体,而其余各单体系F_1 PMCs中Ⅰ构型则表现为18个二价体,1个四价体和1个单价体,即18~Ⅱ 1~Ⅰ 1~Ⅳ。因此,可以肯定“丰抗13”存在1个染色体易位,其有关染色体就是4B和1D。     

The cloned human oestrogen receptor contains a mutation which alters its hormone binding properties.

We demonstrate here that the human oestrogen receptor (hER) cDNA clone pOR8 obtained from MCF-7 cells contains an artefactual point mutation which results in the substitution of a valine for a glycine at amino acid position 400 (Gly-400----Val-400). This mutation in the hormone binding domain of the cloned hER destabilizes its structure and decreases its apparent affinity for oestradiol at 25 degrees C, but not at 4 degrees C, when compared with the wild-type hER with a Gly-400.     

Diffusivity of oxygen into carriers entrapping whole cells

The effective diffusivity of oxygen, D(e), in Ca-alginate and PVA-SbQ gels was measured using a two-chamber vessel with a membrane between the two chambers. The effect of cell density, C(c), on D(e) in Ca-alginate gels was studied. The effective diffusivity of oxygen decreased with increasing cell density, to C(c) = 170 kg dry cells/m(3) gel. The dependency of D(e) on cell density was discussed in terms of a random-pore model. The model correlated well with experimental data, i.e., kD(e)/D(0) = 0.86(1 - 1.47 x 10(-3) C(c))(2). Here, k is the partition coefficient, and D(0) is diffusivity in water.     

Acetone-butanol-ethanol (ABE) fermentation in an immobilized cell trickle bed reactor

Acetone-butanol-ethanol (ABE) fermentation was successfully carried out in an immobilized cell trickle bed reactor. The reactor was composed of two serial columns packed with Clostridium acetobutylicum ATCC 824 entrapped on the surface of natural sponge segments at a cell loading in the range of 2.03-5.56 g dry cells/g sponge. The average cell loading was 3.58 g dry cells/g sponge. Batch experiments indicated that a critical pH above 4.2 is necessary for the initiation of cell growth. One of the media used during continuous experiments consisted of a salt mixture alone and the other a nutrient medium containing a salt mixture with yeast extract and peptone. Effluent pH was controlled by supplying various fractions of the two different types of media. A nutrient medium fraction above 0.6 was crucial for successful fermentation in a trickle bed reactor. The nutrient medium fraction is the ratio of the volume of the nutrient medium to the total volume of nutrient plus salt medium. Supplying nutrient medium to both columns continuously was an effective way to meet both pH and nutrient requirement. A 257-mL reactor could ferment 45 g/L glucose from an initial concentration of 60 g/L glucose at a rate of 70 mL/h. Butanol, acetone, and ethanol concentrations were 8.82, 5.22, and 1.45 g/L, respectively, with a butanol and total solvent yield of 19.4 and 34.1 wt %. Solvent productivity in an immobilized cell trickle bed reactor was 4.2 g/L h, which was 10 times higher than that obtained in a batch fermentation using free cells and 2.76 times higher than that of an immobilized CSTR. If the nutrient medium fraction was below 0.6 and the pH was below 4.2, the system degenerated. Oxygen also contributed to the system degeneration. Upon degeneration, glucose consumption and solvent yield decreased to 30.9 g/L and 23.0 wt %, respectively. The yield of total liquid product (40.0 wt %) and butanol selectivity (60.0 wt %) remained almost constant. Once the cells were degenerated, they could not be recovered.     

Basic fibroblast growth factor induces retinal regeneration in vivo

In the present study, we have investigated the effect of basic fibroblast growth factor (bFGF) on retinal regeneration in the stage 22-24 chick embryo. The neural retina was surgically removed in ovo leaving the retinal pigment epithelium (RPE) intact and then slow-release, plastic implants containing bFGF were inserted into the eye. Light microscopic examination of eyes 7 days later revealed that bFGF induced retinal regeneration in a dose-dependent manner. The absence of the RPE in these eyes and the reversed polarity of the regenerated neural retina is consistent with the hypothesis that this process occurs by transdifferentiation of the RPE. This represents the first time that a known molecule has been shown to induce retinal regeneration in vivo.