Glycosyl donors with cyclic silyl protecting groups, such as di-tert-butylsilylene (DTBS) and tetraisopropyldisiloxanylidene (TIPDS) groups, have been found to affect the stereoselectivity of diverse chemical glycosylations. Moreover, the effects of ring-restriction for stereoselective glycosylations have provided new insights into the reaction mechanism of chemical glycosylation. We present a historical overview of stereoselective glycosylations using such ring-restricted glycosyl donors and their applications to the synthesis of biologically relevant carbohydrate molecules.
Denitrification, which converts soil nitrogen to nitrogen gas, involves a great loss of nitrogen fertilizer. Controlling the process of denitrification rate could help reducing the losses of applied nitrogen fertilizer in crop fields. Fertilizer nitrogen is one of the major concerns due to the high energy demand for its production. Since flooded rice soils are known to have strong denitrifying activity, innovative techniques are emerging as needs to improve nitrogen fertilizer retention efficiency in flooded rice soils. Nitrous oxide (N2O) emissions are not considered as significant, compared to that of methane (CH4) emissions from flooded rice soils, most probably due to its complete denitrification process with prolonged submergence that favors the production of nitrogen (N2) gas. This is due to a further reduction of N2O to N2. However, efficient use of nitrogen in the rice soils could have the benefits of saving energy costs that are being spent on nitrogen fertilizers in many developing countries. While conventional approaches are less efficient in controlling denitrification, technical solutions are emerging to solve this need. Technical solutions based on soil redox potential (Eh) for the control of denitrification have not been adequately covered. We propose that applicability of microbial fuel cell based on soil redox chemistry would be more promising for the control of denitrification in flooded rice soils.
In the past few decades, there has been an increasing awareness of the importance of consuming a diet high in fresh fruits and vegetables, which has led to substantial changes in food habits and consumption of humans. To accommodate this awareness, novel postharvest technologies are needed for extending the shelf-life of fresh produce. High-, hyperbaric, and hypobaric pressure methods have been introduced to reduce microbial growth, preserve nutritional quality, and enhance antioxidant enzyme activity in fresh produce. The high-pressure method is the most practical for use in food industry, to inactivate microorganisms in processed products; however, excessive pressure causes physical cell damage when applied to fresh produce. The hypobaric and hyperbaric methods are two emerging techniques highly capable of prolonging the shelf-life of fresh produce. Both hypobaric and hyperbaric methods prevent cellular damage and reduce respiration rates, ethylene production, and microbial growth. However, the mechanism of quality preservation underlying these methods needs to be explored in future studies.
Melanin is the pigment in the human and animal skin that is synthesized by tyrosinase from L-tyrosine to L-DOPA, following the oxidation of L-DOPA to L-DOPA quinone. Skin whitening agents have been desired as treatment of skin diseases caused by the excess accumulation of melanin on the human skin, because skin darkening is one of the serious aesthetic problems in human beings. Inhibiting the tyrosinase activity and the protein expression are the target to develop the skin whitening agent. A large number of active compounds have been isolated and identified from natural product to develop whitening agents so far. This review reports the potential of traditional medicinal plant extractives and the effective novel ingredients as anti-melanogenesis.
Increasing habitat range and population size of wild boar has been of concern in Japan due to the risk for worsening crop damage. Inobuta, a crossbreed of wild boar and domestic pig (Sus scrofa), is strongly suspected of contributing to these increases in range and population size of wild boar. Genetic analyses used to detect Inobuta from wild boar population in Japan are reviewed here. Previous studies had revealed Inobuta existed in multiple localities in Japan. Furthermore, comparison between production process of Inobuta and its actual genetic profile in the wild indicates that gene flow from Inobuta to wild boar population had continued for multiple generations. However, it is difficult to estimate the degree of impact of Inobuta that still remain in the wild, due to lack of continuous study focused on same locality or population. From both aspects of crop damage control and conservation of genetic structure of wild boar population in Japan, the need for continuous genetic analyses that cover many localities are emphasized.
The destabilization or phase separation of oil-in-water (O/W) emulsions, such as mayonnaise, is common during freezing and after thawing. However, emulsions must remain physically and chemically stable throughout processing, freeze-storage, and thawing. Different factors associated with the destabilization of mayonnaise and other O/W food emulsions include emulsifier, salt, and sugar concentrations, microstructure, cooling temperature, and crystallization of the oil and water phases. Herein, the role of each factor is reviewed, with probable mechanisms discussed. Knowledge of the fundamental physicochemical processes responsible for the stability of mayonnaise-type emulsions will aid the design of quality storage attributes.
Starch is one of the most important components in the food industry. However, the functional properties of native starch bring some disadvantages. Starch modification could overcome these weaknesses using several methods; one of them is the annealing process. This review provides information on the effects of the annealing process on the physicochemical, morphological and gelatinization properties of various types of cereal starch. The review also discusses the reasons for the variation in how the annealing process affects the properties of cereal starches. Overall, these different effects of the annealing process are caused by the different types of cereal starch, annealing conditions, and measurement methods. Annealed cereal starches have the potential for wider application in the food industry as ingredients in canned and frozen foods, noodles, and functional foods.
Cellular Automaton (CA) consists of a regular grid cells of which states change according to simple repetitive rules regulated by their contiguous and adjacent cells, which often expresses an unexpected complexity. Thus, CA is one of the major techniques to imitate and/or assess complex behaviors of natural systems. CA can be applied to physical and biological phenomena, such as turbulence in fluid, patterns of biological growth, and wildfire, and also some human-induced phenomena such as urban growth that is the main target of this review. In 1970s, cellular approach was initially adopted in geography, showing the clue to the urban growth application. To overcome the limitation or constraints the conventional standard cell-space models inherently include, alternative formulations were theoretically proposed in 1980s. And the pioneering work applied to realistic cities was conducted in 1990s. Subsequently, numerous models have been presented by relaxing original rules to express reality and by introducing some additional techniques such as geographical information system and system dynamics, thus far. This paper reviews 87 published cellular automata studies on urban growth simulations, urban land use change assessments, urban planning and related information from 18 countries, and examines the characteristics of each relaxation method. In addition, the scale problems are frequently discussed in the validation of the CA model is addressed.
LysR-type transcriptional regulators (LTTRs) comprise one of the largest families of transcriptional regulators in bacteria and control gene expression of various types of metabolic, virulence and physiological functions. LTTRs typically form homotetramers and require an inducer molecule(s) to activate the transcription of target genes. The N-terminal region of LTTRs contains a DNA-binding domain (DBD) with the winged helix-turn-helix motif that specifically binds the promoter region of target genes. The C-terminal region of LTTRs is connected to the DBD by a linker helix and forms the regulatory domain (RD) that contains a binding pocket for inducer molecules. Crystal structures of several LTTR family members together with their biochemical analyses have provided a potential mechanism for the initial process of transcriptional activation by LTTRs. First, helix α3 of the winged helix-turn-helix motif in DBD is supposed to distinguish the recognition binding site (RBS) in the promoter region, resulting in complex formation through interactions between two DBDs in the tetrameric LTTR and RBS. Formation of this complex seems to enable interactions between the other two DBDs in the LTTR tetramer and the activation binding site (ABS) in the promoter region. The binding of the tetrameric LTTR to both the RBS and ABS causes the promoter DNA to adopt a bent structure because the four DBDs in the tetrameric LTTR are arranged in a V-shaped manner at the bottom of the LTTR. Interaction of an inducer molecule(s) with the RD seems to cause a quaternary structural change of the LTTR that relaxes the bending angle of the promoter DNA with a concomitant shift of the bound DBDs at the ABS. These events facilitate recruitment of RNA polymerase to its binding site in the promoter region, which overlaps with the ABS for LTTR.
Water resource management on a watershed-scale becomes crucial to cope with expected water shortage in the future. One of the key factors in water resource management is forest management, since forest cover changes have large impacts on hydrological processes on watershed scale. Afforestation, forest thinning, clear-cutting and tree species conversion are the most common techniques of forest cover managements. Though it is essential for water resource management, how the forest cover management impacts on hydrological processes has not been systematically understood. Thus, we reviewed the effects of the above four technics in forest cover management on the runoff characteristics from various watersheds in the world. Afforestation is not suitable for countries with a little precipitation because mature forests can reduce much amount of runoff. On the other hands, planting trees in the upland part of the catchment can reduce the flood risk in the downstream area. Thinning and clear cutting can increase the amount of runoff, but at the same time, can decrease the water quality of streamflow. Converting natural/secondary forests to a single plant forest strongly decreases the total amount of runoff. The broadleaf deciduous can produce higher annual runoff but control flood discharge than evergreen coniferous forest. To replace pine trees with eucalyptus for forest plantation has a positive effect on the total amount of timber that can be produced but has a huge impact in decreasing water resource, because of high water consumption of eucalyptus for its growing up fast.