Recent advances in conifer somatic embryogenesis: improving somatic embryo quality

Somatic embryogenesis of coniferous species was first reported more than 20 years ago. Since then, there has been an explosion of research aimed at developing and optimizing protocols for efficient regeneration of plantlets. Although routinely used both as a means of propagation, as well as a valuable model system for investigating the structural, physiological, and molecular events occurring during embryo development, in vitro embryogenesis is still problematic for some coniferous species. Major problems include: low number of embryos generated; and low frequency of mature embryos able to convert into viable plantlets. Until recent years, despite the fact that embryogenesis is comprised of a sequence of defined steps which include proliferation of embryogenic tissue, embryo maturation, and germination, attempts at improving the whole procedure have been made almost exclusively during the maturation stage. This strategy was based on the assumption that successful regeneration is related to treatments provided during the development of the embryos. Major optimizations of the maturation medium have involved judicious selections of type and concentration of growth regulators, namely abscisic acid, and adjustments of the osmoticum of the culture medium. Extensive work has been conducted in defining the effects of plasmolysing and non-plasmolysing osmoticum agents during maturation, as well as in improving desiccation techniques required for the completion of the maturation program. In the last 2 years, however, work on spruce has clearly demonstrated that the early events in embryogenesis are crucial for the successful completion of the overall embryogenic program. The use of cell tracking techniques, implemented by physiological and molecular studies, has revealed that manipulations of the culture conditions early in the process can increase both number and quality of embryos produced in culture. Additional manipulations of the germination medium can also enhance germination and conversion frequency of somatic embryos matured in a sub-optimal environment. These new findings, together with the unraveling of molecular mechanisms involved in the control/regulation of embryo development hold considerable promise for clonal propagation in conifers.     

Recent advances in biological imaging

Recent innovations in microscopy and digital image processing have greatly enhanced the power of biological imaging. Basic principles of several new methods in light and electron microscopy will be discussed, and examples presented of their application to cell and molecular biology.     

Recent advances in synthetic glycoengineering for biological applications

Carbohydrates are involved in many important biological events such as protein maturation and trafficking, pathogen invasion, immune response, cell–cell communications, and so on. Synthetic and chemoenzymatic approaches for glycoengineering have emerged and been applied in perturbing and modulating the biological processes at the protein or cellular level. In this review, we summarize the recent advances in glycoengineering, including new strategies in chemoenzymatic synthesis of glycans, glycopeptides, glycoproteins, and other glycoconjugates. And, the progresses of cell-surface glyco-editing methods for gain of functions are also discussed.

1. Download : Download high-res image (90KB)
2. Download : Download full-size image

     

Recent advances in breeding for improving iron utilization by plants

Iron-chlorosis deficiency may occur when an iron-inefficient genotype is grown on calcareous soil. One way to correct the problem is to modify the genotype by plant breeding. Cultivars have been released for oat (Avena byzantina C. Koch), sorghum [Sorghum bicolor (L.) Moench], dry bean (Phaseoulus vulgaris L.), and soybean [Glycine max (L.) Merr.]. Progress is being made in peanut (Arachis hypogea L.), forage species such as clovers (Trifolium sp.) and bluestems (Botriochloa sp.), and pepper (Capsicum annuum L.). Screening of rootstocks is done on citrus (Citrus sp.), mango (Manguifera indica L.), and avocado (Persea americana Mill.).     

Recent advances in hydrogen peroxide imaging for biological applications

Mounting evidence supports the role of hydrogen peroxide (H₂O₂) in physiological signaling as well as pathological conditions. However, the subtleties of peroxide-mediated signaling are not well understood, in part because the generation, degradation, and diffusion of H₂O₂ are highly volatile within different cellular compartments. Therefore, the direct measurement of H₂O₂ in living specimens is critically important. Fluorescent probes that can detect small changes in H₂O₂ levels within relevant cellular compartments are important tools to study the spatial dynamics of H₂O₂. To achieve temporal resolution, the probes must also be photostable enough to allow multiple readings over time without loss of signal. Traditional fluorescent redox sensitive probes that have been commonly used for the detection of H₂O₂ tend to react with a wide variety of reactive oxygen species (ROS) and often suffer from photostablilty issues. Recently, new classes of H₂O₂ probes have been designed to detect H₂O₂ with high selectivity. Advances in H₂O₂ measurement have enabled biomedical scientists to study H₂O₂ biology at a level of precision previously unachievable. In addition, new imaging techniques such as two-photon microscopy (TPM) have been employed for H₂O₂ detection, which permit real-time measurements of H₂O₂in vivo. This review focuses on recent advances in H₂O₂ probe development and optical imaging technologies that have been developed for biomedical applications.     

Recent advances in genetic modification systems for Actinobacteria

Applied Microbiology and Biotechnology - Actinobacteria are extremely important to human health, agriculture, and forests. Because of the vast differences of the characteristics of Actinobacteria,...     

Microbiological indoor air quality in healthy buildings

There is a growing interest in indoor air quality for a better quality environment both at home and at work because many people spend at least 80% of their time indoors. The aim of our study was to evaluate the indoor concentration of airborne bacteria and fungi in a University auditorium, in an office of public buildings and in an apartment in the presence and in absence of building's occupants, building materials and furnishings. The concentrations of airborne bacteria and fungi were determined using a Surface Air System (SAS). In presence of people and furnishings the average air concentrations of bacteria (University auditorium: 925-1225 CFU m(-3); office: 493 CFU m(-3); apartment: 92-182 CFU m(-3)) were higher than in absence (respectively: 190-315 CFU m(-3); 126 CFU m(-3); 66-80 CFU m(-3)). The average air concentrations fungal were higher in presence of people and furnishings (University auditorium: 1256-1769 CFU m(-3); office: 858 CFU m(-3); apartment: 147-297 CFU m(-3)) than in absence (respectively: 301-431 CFU m(-3); 224 CFU m(-3); 102-132 CFU m(-3)). The obtained data can be considered as a step to identify acceptable levels for bioaerosols in common indoor environments.     

Recent advances in biological production of erythritol

Erythritol is a natural sweetener commonly used in the food and pharmaceutical industries. Produced by microorganisms as an osmoprotectant, it is an ideal sucrose substitute for diabetics or overweight persons due to its almost zero calorie content. Currently, erythritol is produced on an industrial scale through the fermentation of sugars by some yeasts, such as Moniliella sp. However, the popularity of erythritol as a sweetener is still small because of its high retail price. This creates an opportunity for further process improvement. Recent years have brought the rapid development of erythritol biosynthesis methods from the low-cost substrates, and a better understanding of the metabolic pathways leading to erythritol synthesis. The yeast Yarrowia lipolytica emerges as an organism effectively producing erythritol from pure or crude glycerol. Moreover, novel erythritol producing organisms and substrates may be taken into considerations due to metabolic engineering. This review focuses on the modification of erythritol production to use low-cost substrates and metabolic engineering of the microorganisms in order to improve yield and productivity.     

Recent advances in liposomal drug-delivery systems

Liposomal drug-delivery systems have come of age in recent years, with several liposomal drugs currently in advanced clinical trials or already on the market. It is clear from numerous pre-clinical and clinical studies that drugs, such as antitumor drugs, packaged in liposomes exhibit reduced toxicities, while retaining, or gaining enhanced, efficacy. This results, in part, from altered pharmacokinetics, which lead to drug accumulation at disease sites, such as tumors, and reduced distribution to sensitive tissues. Fusogenic liposomal systems that are under development have the potential to deliver drugs intracellularly, and this is expected to markedly enhance therapeutic activity. Advances in liposome design are leading to new applicants for the delivery of new biotechology products, such as recombinant proteins, antisense oligonucleotides and cloned genes.     

Recent advances in the biological production of mannitol

Mannitol is a fructose-derived, 6-carbon sugar alcohol that is widely found in bacteria, yeasts, fungi, and plants. Because of its desirable properties, mannitol has many applications in pharmaceutical products, in the food industry, and in medicine. The current mannitol chemical manufacturing process yields crystalline mannitol in yields below 20 mol% from 50% glucose/50% fructose syrups. Thus, microbial and enzymatic mannitol manufacturing methods have been actively investigated, in particular in the last 10 years. This review summarizes the most recent advances in biological mannitol production, including the development of bacterial-, yeast-, and enzyme-based transformations.     

Recent advances in elucidation of biological corrinoid functions

Abstract: Eleven adenosylcorrinoid-dependent rearrangements and elimination reactions have been described during the last four decades of vitamin B₁₂ research. In contrast, only the cobamide-dependent methionine synthase was well established as a corrinoid-dependent methyl transfer reaction. Yet, investigations during the last few years revealed nine additional corrinoid-dependent methyltransferases. Many of these reactions are catalyzed by bacteria which possess a distinct C₁ metabolism. Notably acetogenic and methanogenic bacteria carry out such methyl transfers in their anabolism and catabolism. Tetrahydrofolate or a similar pterine derivative is a key intermediate in these reactions. It functions as methyl acceptor and the methylated tetrahydrofolate serves as a methyl donor.     

Recent advances in biological production of sugar alcohols

1. Download : Download high-res image (87KB)
2. Download : Download full-size image

     

植物病毒载体系统研究进展

植物病毒基因组小,易于进行遗传操作而且感染过程简单,因而利用植物病毒载体表达外源基因在生物技术领域具有潜在的应用优势。本文主要介绍了抗原展示系统和多肽表达系统,并分别列举一些植物病毒作为表达载体的研究进展情况以及应用前景。     

New units for indoor air quality: decicarbdiox and decitvoc

Abstract Two new units are proposed for the evaluation of indoor air quality using the decibel concept, which give a much better approximation of the human perception of odour intensity, compared to the CO₂ and total volatile organic compounds (TVOC) concentration scales: the decicarbdiox and the devitvoc. On the psychophysical scale according to Yaglou, the weakest odour that can be detected by the human smell sensors is equal to one, and corresponds to the lower limit of percentage dissatisfaction (PD) of 5.8%. It is equivalent to: (1) a CO₂ threshold concentration of 485 ppm – 0 dB (odour CO₂) – 0 dCd (decicarbdiox), and (2) a TVOC threshold concentration of 50 μg m⁻³– 0 dB (odour TVOC) – 0 dTv (decitvoc). The upper limit is determined by the initial value of toxicity: (1) CO₂– 15,000 ppm – 134 dCd, and (2) TVOC – 25,000 g/m⁻³– 135 dTv. Optimal pollutant values (corresponding to PD=20%) and admissible values (PD=30%) for unadapted and adapted persons are calculated. Long-term tolerable values (determining the sick building syndrome range) and short-term tolerable values (the beginning of the toxic range) are also stated. The same system used to evaluate noise can be used to evaluate air quality. Additionally, the contribution of the individual constituents (at present acoustic and odour) to the overall quality of the environment can be ascertained. The new units dCd and dTv can express an increase or decrease in air contamination, e.g. by the use of air cleaners, new building materials etc. The proposed system of using dCd and dTv is compatible with BSR/ASHRAE 62–1989 R which can be used to determine the required volume of fresh air for ventilation by an improved method, which takes into account different levels of required indoor air quality. Received: 21 January 1998 / Revised: 20 May 1998 / Accepted: 30 September 1998     

Recent advances in improving metabolic robustness of microbial cell factories

1. Download : Download high-res image (92KB)
2. Download : Download full-size image

     

Chemical characterization of indoor air quality in Parisian homes

Summary Air quality inside 9 homes in the Paris region was evaluated by measuring several atmospheric pollutants. In these homes interior emissions of ammonia and volatile organic compounds were obvious. Regarding other pollutants such as sulphur dioxide, nitrogen dioxide, particles, polycyclic aromatic hydrocarbons, sulphate and metals, the influence of external surrounding air remains predominant.