Pseudouridine in RNA: what, where, how, and why

Pseudouridine (5-ribosyluracil) is a ubiquitous yet enigmatic constituent of structural RNAs (transfer, ribosomal, small nuclear, and small nucleolar). Although pseudouridine (psi) was the first modified nucleoside to be discovered in RNA, and is the most abundant, its biosynthesis and biological roles have remained poorly understood since its identification as a "fifth nucleoside" in RNA. Recently, a combination of biochemical, biophysical, and genetic approaches has helped to illuminate the structural consequences of psi in polyribonucleotides, the biochemical mechanism of U-->psi isomerization in RNA, and the role of modification enzymes (psi synthases) and box H/ACA snoRNAs, a class of eukaryotic small nucleolar RNAs, in the site-specific biosynthesis of psi. Through its unique ability to coordinate a structural water molecule via its free N1-H, psi exerts a subtle but significant "rigidifying" influence on the nearby sugar-phosphate backbone and also enhances base stacking. These effects may underlie the biological role of most (but perhaps not all) of the psi residues in RNA. Certain genetic mutants lacking specific psi residues in tRNA or rRNA exhibit difficulties in translation, display slow growth rates, and fail to compete effectively with wild-type strains in mixed culture. In particular, normal growth is severely compromised in an Escherichia coli mutant deficient in a pseudouridine synthase responsible for the formation of three closely spaced psi residues in the mRNA decoding region of the 23S rRNA. Such studies demonstrate that pseudouridylation of RNA confers an important selective advantage in a natural biological context.     

Pollen,ovules, and pollination in pea: Success,failure, and resilience in heat

Field pea (Pisum sativum), a major grain legume crop, is autogamous and adapted to temperate climates. The objectives of this study were to investigate effects of high temperature stress on stamen chemical composition, anther dehiscence, pollen viability, pollen interactions with pistil and ovules, and ovule growth and viability. Two cultivars (“CDC Golden” and “CDC Sage”) were exposed to 24/18°C (day/night) continually or to 35/18°C for 4 or 7 days. Heat stress altered stamen chemical composition, with lipid composition of “CDC Sage” being more stable compared with “CDC Golden.” Heat stress reduced pollen viability and the proportion of ovules that received a pollen tube. After 4 days at 35°C, pollen viability in flower buds decreased in “CDC Golden,” but not in “CDC Sage.” After 7 days, partial to full failure of anthers to dehisce resulted in subnormal pollen loads on stigmas. Although growth (ovule size) of fertilized ovules was stimulated by 35°C, heat stress tended to decrease ovule viability. Pollen appears susceptible to stress, but not many grains are needed for successful fertilization. Ovule fertilization and embryos are less susceptible to heat, but further research is warranted to link the exact degree of resilience to stress intensity.     

Nomadization in Rajasthan, India: Migration, Institutions, and Economy

Despite a global trend toward settlement, the incidence of pastoral nomadism is on the rise in the Marwar region of Rajasthan, India. Typical explanations for this change use models of population pressure; increasing herds and decreasing pasture are held to blame. This explanation, however intuitive, is unsatisfactory. Instead, changing institutional and economic patterns are creating new contexts for strategic movement. Bottlenecks in the yearly resource calendar, caused by the disintegration of obligatory social relationships, force migrations during periods of scarcity. Changes in the volume and pattern of the meat and wool markets have also created opportunities for migrating pastoralists. Producers increase their access to markets and the reproductive rate of their herd through long, annual, migration. While nomadism is a general adaptation to changes in the socioeconomic conditions of the region, differential resource endowments account for the range of strategies; wealthy herders have opportunities not enjoyed by more marginal producers.     

Kahnawa:ke: Factionalism, Traditionalism, and Nationalism in a Mohawk Community

Kahnawa:ke: Factionalism, Traditionalism, and Nationalism in. Mohawk Community . Gerald F. Reid. Lincoln: University of Nebraska Press, 2004. 235 pp.     

Glutamate in plants: metabolism, regulation, and signalling

Glutamate occupies a central position in amino acid metabolism in plants. The acidic amino acid is formed by the action of glutamate synthase, utilizing glutamine and 2-oxoglutarate. However, glutamate is also the substrate for the synthesis of glutamine from ammonia, catalysed by glutamine synthetase. The alpha-amino group of glutamate may be transferred to other amino acids by the action of a wide range of multispecific aminotransferases. In addition, both the carbon skeleton and alpha-amino group of glutamate form the basis for the synthesis of gamma-aminobutyric acid, arginine, and proline. Finally, glutamate may be deaminated by glutamate dehydrogenase to form ammonia and 2-oxoglutarate. The possibility that the cellular concentrations of glutamate within the plant are homeostatically regulated by the combined action of these pathways is examined. Evidence that the well-known signalling properties of glutamate in animals may also extend to the plant kingdom is reviewed. The existence in plants of glutamate-activated ion channels and their possible relationship to the GLR gene family that is homologous to ionotropic glutamate receptors (iGluRs) in animals are discussed. Glutamate signalling is examined from an evolutionary perspective, and the roles it might play in plants, both in endogenous signalling pathways and in determining the capacity of the root to respond to sources of organic N in the soil, are considered.     

Adaptation in Sport: Present State, Problems, Prospects

The current state of the problem of adaptation in sport, its theoretical and practical aspects, and also prospects of its development are considered. Specific features of the mechanisms and regularities of adaptation to exercise were studied in athletes over 15 years. Four stages of adaptive rearrangements are proposed: physiological tension of the organism, adaptation, dysadaptation, and readaptation. Each stage is characterized by specific functional changes and regulatory and energy provision. The concept of a special functional system of adaptation in athletes is based theoretically and confirmed experimentally. Knowledge of the regularities of the development of this system allows us to efficiently and variously influence its links to accelerate adaptation to exercise and to increase training, i.e., to control the adaptation process.     

Phytoecdysteroids: Structure,Sources, and Biosynthesis in Plants

Data on the content of ecdysteroids in plant sources are given and the ecdysteroid biosynthesis and role in plants are discussed.     

JGG in 2022: challenges,opportunities, and prospects

<正>During the past 2022, the Journal of Genetics and Genomics(JGG) has seen a variety of challenges as well as opportunities. At the difficult time of the COVID-19 pandemic, we have gone through unforeseen difficulties, including the cancellation of academic conferences, drop in submissions, work from home, and infections.Despite all these challenges, however, our authors, readers, reviewers, and editorial members have all supported and witnessed the progress of JGG. In 2022, JGG has publi...     

Algeria in France: Transpolitics, Race, and Nation

Algeria in France: Transpolitics, Race, and Nation. Paul A. Silverstein. Indianapolis: Indiana University Press, 2004. 284 pp.