Regioselective enzymatic acylation of N-acetylhexosamines

A careful choice of the reaction conditions (solvent, enzyme, acylating agent) allowed an efficient regioselective acylation of N-acetylhexosamines. 6-O-Acyl derivatives of 2-acetamido-2-deoxy- -glucopyranose (GlcNAc), 2-acetamido-2-deoxy- -galactopyranose (GalNAc) and 2-acetamido-2-deoxy- -mannopyranose (ManNAc) have been isolated from regioselective esterifications catalysed by the protease subtilisin in CH₃CN–DMSO 8:2 in good yields.     

Minerals in the Blood,Hair, and Faeces of the Critically Endangered Western Derby Eland Under Human Care in Two Wildlife Reserves in Senegal

Biological Trace Element Research - This study was experimentally conducted between 2017 and 2018 in order to determine the interactions of heavy metals and non-smoking status of adolescents in...     

Effect of inhibition of phenylalanine ammonia-lyase activity on growth of alfalfa cell suspension culture: Alterations in mitotic index, ethylene production, and contents of phenolics, cytokinins and polyamines

The effect of inhibition of phenylpropanoid biosynthesis on the growth of Medicago sativa L. suspension culture was studied. 2-Aminoindan-2-phosphonic acid (AIP), a potent inhibitor of phenylalanine ammonia-lyase (PAL; EC 4.3.1.5), caused a marked reduction in the amount of hydroxycinnamic acid derivatives in a few hours after cell inoculation into AIP medium. The treatment of alfalfa suspension culture with this inhibitor increased the extractable PAL activity and elevated ethylene production during the growth cycle. The addition of AIP (10 μ M ) stimulated cell division activity during the growth cycle, although the onset of cell division was slightly delayed. The maxima of cytokinin content as well as of the mitotic index were postponed in AIP-treated cells, however, the unchanged content of cytokinins did not correlate with increased mitotic activity of treated cells. The decreased level of hydroxycinnamic acid derivatives, which represent the phenolic conjugation partners of free polyamines (PAs), influenced the rate of PA conjugation. Consequently, the balance between free and conjugated PAs was shifted in favor of the free PA form. A potential role of the reduction of the pool of phenolic acids in the enhancement of cell division of alfalfa cell suspension culture is discussed.     

Localization of prophages of serological group B and F on restriction fragments defined in the restriction map of Staphylococcus aureus NCTC 8325

Abstract Several Staphylococcus aureus strains were lysogenized by the phages of serological group B (phages φ53, φ85) as well as by some of serological group F (phages φ77, φ84) and macrorestriction fragment patterns of genomic DNA were estimated in the lysogenized, non-lysogenic and delysogenized (cured of prophages) strains. It was shown that the integration of phage DNA into chromosome of S. aureus leads to specific changes in restriction fragment pattern in all the lysogenized strains. These changes correlate well with the Sma I restriction map of S. aureus NCTC 8325 since they concern the restriction fragments defined in this map. Phages φ53 and φ85 integrate into Sma I fragment B. On the other hand, phages φ77 and φ84 integrate into Smal fragment E of the S. aureus restriction map. The prophages of strain NCTC 8511 have their integration sites, as follows: the phage designated by us φM integrates in fragment A, whereas the integration site for phage φJ lies in fragment E. Phage φM was estimated to be genetically related to phages of serological group A and phage φJ to those of serological group F. Evidence was given that lysogenization of S. aureus strains by at least four prophages does not cast any doubt upon the estimation of their genetic relatedness based on their similarity in restriction pattern.     

Performance and Mortality of Rumex obtusifolius and R. crispus in Managed Grasslands are Affected by Nutrient Availability

The reasons for the greater incidence of Rumex obtusifolius in grasslands compared with R. crispus have never been investigated. In a small-plot field experiment in which seedlings of R. obtusifolius and R. crispus were transplanted into a sward dominated by Dactylis glomerata, the growth and survival of seedlings were monitored over three years under control and P, N, NP and NPK fertilizer treatments. The highest plants of R. obtusifolius and R. crispus were generally recorded in the N, NP and NPK treatments and the lowest in the control and P treatment. The maximum recorded heights of R. obtusifolius were 100?cm and of R. crispus 80?cm. The number of leaves per plant, weight of individual plants, cover and fertility were generally higher for R. obtusifolius than for R. crispus. 30% to 80% of transplanted R. obtusifolius plants flowered in the first (seeding) year and this contrasted with no flowering of transplanted R. crispus plants. After cutting, substantially better regrowth of R. obtusifolius was recorded compared to that of R. crispus and surviving R. crispus plants tended to show a gradual reduction in leaf number. The mortality of R. obtusifolius over three years ranged from 0% in the NPK treatment to 13% in the control, with an average of 8% over all treatments. The mortality of R. crispus ranged from 19% in the control to 94% in the NPK treatment with an average of 64% over all treatments. We concluded that R. obtusifolius is better adapted to growing in highly productive temperate grasslands than R. crispus because of its perennial character, larger plant size and higher fertility.     

Reinitiation of cell division and polyamine and aromatic monoamine levels in alfalfa explants during the induction of somatic embryogenesis

The early cellular events in leaf explants of Medicago sativa L. cultured on somatic embryogenesis- and callogenesis-inducing media (EIM and CIM, respectively) were correlated with the endogenous contents of polyamines (PAs) and aromatic monoamines (AMs). On the second day of culture, replication of DNA occurred in epidermal and subepidermal cells on the edges of explants on EIM and was a prerequisite for proembryonal mass and, later, globular proembryo formation. In explants cultured on CIM, replication occurred at least one day later and in fewer cells, which were randomly spread all over the explant. Transition of leaf explant cells to rapidly dividing meristematic-like cells on EIM or to enlarged, highly vacuolated cells on CIM was observed. The increase in total PA levels in cultured explants was primarily a consequence of increases in putrescine (Put) and spermidine (Spd) contents and was much more pronounced on EIM than on CIM. High Spd levels were characteristic of meristematic cells and might be essential for the development of globular structures. The higher amount of insoluble PA conjugates was determined in explant cells on EIM, as compared with CIM. Proembryogenic cell mass formation was positively correlated with free tyramine and negatively correlated with free phenylethylamine contents.