Methyltransferase activity in Allanthm altissima cell suspension cultures

Enzymes for the methylation of 1hydroxycanthin-6-one and a series of coumarins have been isolated from Ailanthus altissima cell suspension cultures. The coumarin methyltransferases methylate aesculetin to scopoletin and isoscopoletin, but not scopoletin, to scoparone. Fraxetin was methylated to isofraxidine but not to fraxidine and only fraxidine was methylated to 6,7,8-trimethoxycoumarin. These enzymes were studied throughout the culture growth cycle with two cell lines: 1, which produced 1-methoxycanthin-6-one as the major alkaloid and 2, in which canthin-6-one was the major alkaloid.Abbreviations UV ultraviolet - DEAE diethylaminoethyl - dw dry weight - MS mass spectrometry - NMR nuclear magnetic resonance - TLC thin layer chromatography     

Beneficial bacteria of agricultural importance

The rhizosphere is the soil–plant root interphase and in practice consists of the soil adhering to the root besides the loose soil surrounding it. Plant growth-promoting rhizobacteria (PGPR) are potential agents for the biological control of plant pathogens. A biocontrol strain should be able to protect the host plant from pathogens and fulfill the requirement for strong colonization. Numerous compounds that are toxic to pathogens, such as HCN, phenazines, pyrrolnitrin, and pyoluteorin as well as, other enzymes, antibiotics, metabolites and phytohormones are the means by which PGPR act, just as quorum sensing and chemotaxis which are vital for rhizosphere competence and colonization. The presence of root exudates has a pronounced effect on the rhizosphere where they serve as an energy source, promoting growth and influencing the root system for the rhizobacteria. In certain instances they have products that inhibit the growth of soil-borne pathogens to the advantage of the plant root. A major source of concern is reproducibility in the field due to the complex interaction between the plant (plant species), microbe and the environment (soil fertility and moisture, day length, light intensity, length of growing season, and temperature). This review listed most of the documented PGPR genera and discussed their exploitation.     

Cytomegalovirus infection in Gambian infants leads to profound CD8 T-cell differentiation

Cytomegalovirus (CMV) infection is endemic in Gambian infants, with 62% infected by 3 months and 85% by 12 months of age. We studied the CD8 T-cell responses of infants to CMV following primary infection. CMV-specific CD8 T cells, identified with tetramers, showed a fully differentiated phenotype (CD28(-) CD62L(-) CD95(+) perforin(+) granzyme A(+) Bcl-2(low)). Strikingly, the overall CD8 T-cell population developed a similar phenotype following CMV infection, which persisted for at least 12 months. In contrast, primary infection was accompanied by up-regulation of markers of activation (CD45R0 and HLA-D) on both CMV-specific cells and the overall CD8 T-cell population and division (Ki-67) of specific cells, but neither pattern persisted. At 12 months of age, the CD8 T-cell population of CMV-infected infants was more differentiated than that of uninfected infants. Although the subpopulation of CMV-specific cells remained constant, the CMV peptide-specific gamma interferon response was lower in younger infants and increased with age. As the CD8 T-cell phenotype induced by CMV is indicative of immune dysfunction in the elderly, the existence of a similar phenotype in large numbers of Gambian infants raises the question of whether CMV induces a similarly deleterious effect.     

Plant growth-promoting rhizobacteria do not pose any deleterious effect on cowpea and detectable amounts of ethylene are produced

Summary The use of trap crops such as cowpea could reduce the effects of the root parasitic weed, Striga hermonthica and its subsequent constraints on the growth of cereals. Certain bacteria could augment the trap crop stimulatory effect. We studied the effect of three bacteria introduced to the rhizosphere of three cowpea varieties at planting. Number of days to cowpea flowering was noted and at harvest, data were collected on pod characteristics and biomass. Means of data subjected to ANOVA were compared using Tukey’s Studentized Range Test. We analysed bacterial headspace volatiles for ethylene by gas chromatography and gas chromatography–mass spectrometry. Bacterial type significantly influenced the cowpea varieties with better performance over the non-inoculated control. Average pod weight (g) with bacterial treatment was 37.97 for Enterobacter sakazakii 8MR5, 34.38 for Pseudomonas 44MS8 and 27.46 for Pseudomonas 10M3. Non-inoculated control had an average weight of 20.98 g. Bacteria promoted a significant increase in pod weight (≥30.89%), fresh biomass (≥24.22%), and improved pod number (≥20.54%) and pod wall thickness (≥7.33%) with no deleterious effect on plant health. Ethylene released by the bacteria ranged from trace concentrations in Pseudomonas sp. to 210 nmoles/10⁸ c. f. u./ml in Ent. sakazakii 8MR5.     

Mechanisms of action of plant growth promoting bacteria

The idea of eliminating the use of fertilizers which are sometimes environmentally unsafe is slowly becoming a reality because of the emergence of microorganisms that can serve the same purpose or even do better. Depletion of soil nutrients through leaching into the waterways and causing contamination are some of the negative effects of these chemical fertilizers that prompted the need for suitable alternatives. This brings us to the idea of using microbes that can be developed for use as biological fertilizers (biofertilizers). They are environmentally friendly as they are natural living organisms. They increase crop yield and production and, in addition, in developing countries, they are less expensive compared to chemical fertilizers. These biofertilizers are typically called plant growth-promoting bacteria (PGPB). In addition to PGPB, some fungi have also been demonstrated to promote plant growth. Apart from improving crop yields, some biofertilizers also control various plant pathogens. The objective of worldwide sustainable agriculture is much more likely to be achieved through the widespread use of biofertilizers rather than chemically synthesized fertilizers. However, to realize this objective it is essential that the many mechanisms employed by PGPB first be thoroughly understood thereby allowing workers to fully harness the potentials of these microbes. The present state of our knowledge regarding the fundamental mechanisms employed by PGPB is discussed herein.     

Phylogenetic analysis of actinobacterial populations associated with Antarctic Dry Valley mineral soils

Despite the apparent severity of the environmental conditions in the McMurdo Dry Valleys, Eastern Antarctica, recent phylogenetic studies conducted on mineral soil samples have revealed the presence of a wide diversity of microorganisms, with actinobacteria representing one of the largest phylotypic groups. Previous metagenomic studies have shown that the majority of Antarctic actinobacterial populations are classified as 'uncultured'. In this study, we assessed the diversity of actinobacteria in Antarctic cold desert soils by complementing traditional culture-based techniques with a metagenomic study. Phylogenetic analysis of clones generated with actinobacterium- and streptomycete-specific PCR primers revealed that the majority of the phylotypes were most closely related to uncultured Pseudonocardia and Nocardioides species. Phylotypes most closely related to a number of rarer actinobacteria genera, including Geodermatophilus , Modestobacter and Sporichthya , were also identified. While complementary culture-dependent studies isolated a number of Nocardia and Pseudonocardia species, the majority of the cultured isolates (> 80%) were S treptomyces species – although phylotypes affiliated to the genus Streptomyces were detected at a low frequency in the metagenomic study. This study confirms that Antarctic Dry Valley desert soil harbours highly diverse actinobacterial communities and suggests that many of the phylotypes identified may represent novel, uncultured species.     

Protocatechuic acid ameliorates testosterone‐induced benign prostatic hyperplasia through the regulation of inflammation and oxidative stress in castrated rats

Protocatechuic acid (PA) is a polyphenol—recognized for its efficacy as an antioxidant—possesses anticancer, anti‐inflammatory, antioxidant properties. The efficacy of PA in the management of benign prostatic hyperplasia (BPH) has not been investigated. Forty‐two castrated rats (n = 7) were treated as follows: control (corn oil), BPH only received testosterone propionate (TP) (TP 3 mg/kg intraperitoneally), BPH + PA (TP 3 mg/kg + PA 40 mg/kg), BPH + finasteride (Fin) (TP 3 mg/kg + Fin 10 mg/kg), PA only (40 mg/kg: by gavage), and Fin only (10 mg/kg: by gavage) for 4 weeks. In BPH rats, there were significant (P < .05) increases in prostatic (250%) and organosomatic (280%) weights compared with controls. Cotreatment decreased prostatic weights by 19% (PA) and 21% (Fin). Markers of inflammation: myeloperoxidase activities increased in serum (148%) and prostate (70%), as well as nitric oxide levels serum (92%) and prostatic (95%). Proinflammatory cytokines interleukin‐1β and tumor necrosis factor‐α increased by 3.6‐ and 2.8‐fold. Furthermore, prostatic malondialdehyde, superoxide dismutase, and serum total acid phosphatase increased by 97%, 25%, and 48%, respectively. Histology revealed poor architecture and severe proliferation of the prostate in BPH rats. Inflammation and oxidative stress markers, as well as the histological alteration in BPH rats, was attenuated (P < .05) upon cotreatment with PA and comparable with Fin cotreatment. These results suggest that PA mitigates oxido‐inflammatory responses and restored prostatic cytoarchitecture to levels comparable with control in rats induced with BPH.