Pattern analysis of stem cell differentiation during <Emphasis Type="Italic">in vitro Arabidopsis</Emphasis> organogenesis

Plant somatic cells have the capability to switch their cell fates from differentiated to undifferentiated status under proper culture conditions, which is designated as totipotency. As a result, plant cells can easily regenerate new tissues or organs from a wide variety of explants. However, the mechanism by which plant cells have such remarkable regeneration ability is still largely unknown. In this study, we used a set of meristem-specific marker genes to analyze the patterns of stem cell differentiation in the processes of somatic embryogenesis as well as shoot or root organogenesis in vitro. Our studies furnish preliminary and important information on the patterns of the de novo stem cell differentiation during various types of in vitro organogenesis.     

MV-mimicking micelles loaded with PEG-serine-ACP nanoparticles to achieve biomimetic intra/extra fibrillar mineralization of collagen in vitro

Since their discovery, matrix vesicles (MVs) containing minerals have received considerable attention for their role in the mineralization of bone, dentin and calcified cartilage. Additionally, MVs' association with collagen fibrils, which serve as the scaffold for calcification in the organic matrix, has been repeatedly highlighted. The primary purpose of the present study was to establish a MVs–mimicking model (PEG-S-ACP/micelle) in vitro for studying the exact mechanism of MVs-mediated extra/intra fibrillar mineralization of collagen in vivo. In this study, high-concentration serine was used to stabilize the amorphous calcium phosphate (S-ACP), which was subsequently mixed with polyethylene glycol (PEG) to form PEG-S-ACP nanoparticles. The nanoparticles were loaded in the polysorbate 80 micelle through a micelle self-assembly process in an aqueous environment. This MVs–mimicking model is referred to as the PEG-S-ACP/micelle model. By adjusting the pH and surface tension of the PEG-S-ACP/micelle, two forms of minerals (crystalline mineral nodules and ACP nanoparticles) were released to achieve the extrafibrillar and intrafibrillar mineralization, respectively. This in vitro mineralization process reproduced the mineral nodules mediating in vivo extrafibrillar mineralization and provided key insights into a possible mechanism of biomineralization by which in vivo intrafibrillar mineralization could be induced by ACP nanoparticles released from MVs. Also, the PEG-S-ACP/micelle model provides a promising methodology to prepare mineralized collagen scaffolds for repairing bone defects in bone tissue engineering.     

Haploid plant regeneration from unpollinated ovule cultures of niger (<Emphasis Type="Italic">Guizotia abyssinica</Emphasis> (L. f.) Cass.)

Haploid plants were regenerated in vitro from unpollinated ovules of niger (Guizotia abyssinica (L. f.) (Cass.) on Murashige and Skoog nutrient medium (MS) supplemented with 10 μM naphthaleneacetic acid or 10 μM NAA + 1.5 μM kinetin and 30 g/l sucrose. Gamborg (B5) medium was the best for plant regeneration (in comparison with MS, Nitsch and Nitsch (NN), and Chu (N6) media) from cultured ovules, and 6.66 and 7.33 ovules of JNC-6 and Ootacamund cultivars were involved in direct plant regeneration on this medium. Matured ovules (ovules collected one day before anthesis or on the day of anthesis) only responded to cultural regimes and involved in direct plantlet development. Cytological preparation of root tips and chloroplast counts in the guard cells of leaf stomata of regenerated plants confirmed their haploid nature. This text was submitted by the authors in English.     

Effects of Juvenoids and Retinoic Acid on Development of Larvae and Nymphs in the Tick Ixodes ricinus L. (Acari,Ixodidae) and Regeneration of Haller's Organ during Metamorphosis

Larvae and nymphs of the tick Ixodes ricinus L. display similar reactions to analogs of the insect juvenile hormones (methoprene and pyriproxyfen), which induce at both stages juvenalization of the Haller's sense organ regenerates. Similar effects were also described for retinoic acid. Unlike juvenoids, retinoic acid can affect not only regeneration, but also normal development of the Haller's organ and cause changes corresponding to so-called regenerative induction. Amputation of the leg and treatment with retinoic acid do not affect the duration of larval or nymphal development, while juvenoids somewhat accelerate their development.     

Optimization of biotin and thiamine requirements for somatic embryogenesis of date palm (Phoenix dactylifera L.)

Summary This study was conducted to examine the effect of biotin and thiamine concentrations on callus growth and somatic embryogenesis of date palm (Phoenix dactylifera L.). Embryogenic callus derived from offshoot tip explants was cultured on hormone-free MS medium containing biotin at 0, 0.1, 1, or 2 mg l⁻¹ combined with thiamine at 0.1, 0.5, 2, or 5 mg l⁻¹. Embryogenic callus weight, number of resultant embryos, and embryo length were significantly influenced by thiamine and biotin concentration. The optimum callus growth treatment consisted of 0.5 mg l⁻¹ thiamine and 2 mg l⁻¹ biotin. This treatment also gave the highest number of embryos. Embryo elongation was greatest at 0.5 or 2 mg l⁻¹ thiamine combined with 1 mg l⁻¹ biotin. Embryos from all treatments germinated and regenerants exhibited normal growth in soil. This study provides an insight into the importance of optimizing various culture medium components to overcome in vitro recalcitrace of date palm.     

Protoplast formation and regeneration in <Emphasis Type="Italic">Lactobacillus delbrueckii</Emphasis>

Method for production and regeneration of Lactobacillus delbrueckii protoplasts are described. The protoplasts were obtained by treatment with a mixture of lysozyme and mutanolysin in protoplast buffer at pH 6.5 with different osmotic stabilizers. The protoplasts were regenerated on deMan, Rogosa and Sharpe (MRS) with various osmotic stabilizers. Maximum protoplast formation was obtained in protoplast buffer with sucrose as an osmotic stabilizer using a combination of lysozyme (1 mg/ml) and mutanolysin (10 μg/ml). Maximum protoplast regeneration was obtained on MRS medium with sucrose (0.5 M) as an osmotic stabilizer. The regeneration medium was also applicable to other species of lactobacilli as well. This is, to our knowledge, the first report on protoplast formation and efficient regeneration in case of L. delbrueckii.     

Functional Casein-Poly saccharide Conjugates Prepared by Controlled Dry Heating

Casein was conjugated with dextran and galactomannan in a controlled dry state at a relative humidity of 79% and at 60°C for 24 hr. The covalent attachment of polysaccharides to casein was confirmed by SDS-PAGE and HPLC. The emulsifying activity of the casein-dextran and casein-galactomannan conjugates was 1.5 times higher than that of casein. The emulsion stability of the casein-dextran and casein-galactomannan conjugates was 10 times higher than that of casein. The improvement in these emulsifying properties reached a steady state when the conjugation of casein with polysaccharide was done for 24 hr in a controlled dry state, suggesting the rapid formation of conjugates through a Maillard reaction in the case of casein. Compared to commercial emulsifiers, the casein-polysaccharide conjugates showed better emulsifying properties in acidic and high-salt concentration systems.