Interactions of bacterial cytokinins and IAA in the rhizosphere may alter phytostimulatory efficiency of rhizobacteria

Phytohormones from rhizobacterial origin have been linked to their phytostimulation potential. However, while studying the efficacy of plant growth promoting bacteria, focus has always been on a single hormone. The role of plant hormones often overlay and they mutually modulate their effect. In current study focus was on the role of two hormones (cytokinins and indole acetic acid) in phytostimulation by rhizobacteria. Endogenous rhizosphere bacteria were isolated and screened for the presence of phytohormones. Bacterial strains from three different genera (Pseudomonas, Bacillus and Azospirillum) were screened positive for cytokinins and IAA. Phytohormones were simultaneously determined in SPE purified bacterial extract by ultra performance liquid chromatography (UPLC) coupled to a tandem mass spectrometer through electrospray interface. Cytokinins and IAA were determined in positive and negative mode, respectively with MRM scan. Zeatin, zeatin riboside and dihydrozeatin riboside were detected and quantified in the selected strains. Significant positive correlation between cytokinins and IAA in bacterial culture and plant endogenous hormones (r = 0.933 and r = 0.983; P = 0.01, respectively) was observed. However, strains with high IAA to cytokinins ratio could hardly enhance in-planta cytokinins, indicating antagonistic relation between the two hormones. Significant correlation of cytokinin with shoot length (r = 0.797; P = 0.01), fresh weight (r = 0.685; P = 0.01) and dry weight (r = 0.704; P = 0.01) was reported under axenic conditions. Bacterial IAA was correlated negatively to root length (r = 0.853; P = 0.01) and positively correlated to the number of roots (r = 0.964; P = 0.01). In natural conditions maximum increase in spike length (33%), number of tillers (71%) and weight of seeds (39%) was documented at final harvest in bacterially inoculated plants.     

Potential of bacterial indoleacetic acid to induce adventitious shoots in plant tissue culture

AIMS: The main aim of this study was to investigate the possible role of indoleacetic acid (IAA) from bacteria to induce in vitro adventitious shoots in internodal explants of Brassica oleracea L. METHODS AND RESULTS: Culture supernatant of Halomonas sp. RE1 and Halomonas sp. HT1 that contain 21 and 40 microg ml(-1) IAA, respectively, was used to supplement Murashige and Skoog (MS) medium. Two combinations that were supplemented with bacterial supernatant (BS) are MS + BS and MS + BS + 10%CW (coconut water) while basal MS medium was used as control. The amounts of BS used in this experiment were 50, 100, 150 and 200 microl in 5 ml MS medium in each combination. In vitro-grown internodal explants of B. oleracea were inoculated on these media combinations and incubated in a growth chamber at 25 +/- 1 degrees C and exposed to 16-h cool fluorescent light. After 5-6 weeks of incubation adventitious shoot induction was observed in all treatments that were supplemented with BS as compared with the controls where very low response was observed. The frequency of shoot induction was high in media that were supplemented with 10%CW in the presence of bacterial auxin. CONCLUSIONS: It was concluded that IAA of microbial origin has the potential to induce adventitious shoots in internodal explants. SIGNIFICANCE AND IMPACT OF THE STUDY: IAA from bacteria can be effectively used in plant tissue culture; especially a combination of MS + BS + 10%CW is very cost-effective as compared with synthetic phytohormones for in vitro studies.     

Physico-chemical method for ammonia removal from synthetic wastewater using limestone and GAC in batch and column studies

The purpose of the present study was to examine the removal of ammoniacal nitrogen (NH4-N) from synthetic wastewater using limestone (LS) and granular activated carbon (GAC) mixture as low cost adsorbent. In batch study, optimum shaking and settling times were 150 and 120 min, respectively. The LS-GAC mixture ratio of 25:15 removed about 58% NH4-N. The smaller particle size of medium yielded higher adsorption capacity. The equilibrium adsorption data followed the Freundlich isotherm (R2 > 0.98) but it showed weak bond. Adsorption kinetics were well described by the pseudo second-order rate model (R2 > 0.93). The upflow column showed that higher flow rate and initial concentration resulted in shorter column saturation time. The study showed that the usage of GAC could be reduced by combining GAC with LS for the removal of NH4-N from wastewater; thus reducing the cost of treatment.     

Coverage and Quality of Antenatal Care Provided at Primary Health Care Facilities in the ‘Punjab’ Province of ‘Pakistan’

Background

Antenatal care is a very important component of maternal health services. It provides the opportunity to learn about risks associated with pregnancy and guides to plan the place of deliveries thereby preventing maternal and infant morbidity and mortality. In ‘Pakistan’ antenatal services to rural population are being provided through a network of primary health care facilities designated as ''Basic Health Units and Rural Health Centers. Pakistan is a developing country, consisting of four provinces and federally administered areas. Each province is administratively subdivided in to ‘Divisions’ and ‘Districts’. By population ‘Punjab’ is the largest province of Pakistan having 36 districts. This study was conducted to assess the coverage and quality antenatal care in the primary health care facilities in ‘Punjab’ province of ‘Pakistan’.

Methods

Quantitative and Qualitative methods were used to collect data. Using multistage sampling technique nine out of thirty six districts were selected and 19 primary health care facilities of public sector (seventeen Basic Health Units and two Rural Health Centers were randomly selected from each district. Focus group discussions and in-depth interviews were conducted with clients, providers and health managers.

Results

The overall enrollment for antenatal checkup was 55.9% and drop out was 32.9% in subsequent visits. The quality of services regarding assessment, treatment and counseling was extremely poor. The reasons for low coverage and quality were the distant location of facilities, deficiency of facility resources, indifferent attitude and non availability of the staff. Moreover, lack of client awareness about importance of antenatal care and self empowerment for decision making to seek care were also responsible for low coverage.

Conclusion

The coverage and quality of the antenatal care services in ‘Punjab’ are extremely compromised. Only half of the expected pregnancies are enrolled and out of those 1/3 drop out in follow-up visits.     

Mycobacterium tuberculosis DosR regulon gene Rv0079 encodes a putative, 'dormancy associated translation inhibitor (DATIN)'

Mycobacterium tuberculosis is a major human pathogen that has evolved survival mechanisms to persist in an immune-competent host under a dormant condition. The regulation of M. tuberculosis metabolism during latent infection is not clearly known. The dormancy survival regulon (DosR regulon) is chiefly responsible for encoding dormancy related functions of M. tuberculosis. We describe functional characterization of an important gene of DosR regulon, Rv0079, which appears to be involved in the regulation of translation through the interaction of its product with bacterial ribosomal subunits. The protein encoded by Rv0079, possibly, has an inhibitory role with respect to protein synthesis, as revealed by our experiments. We performed computational modelling and docking simulation studies involving the protein encoded by Rv0079 followed by in vitro translation and growth curve analysis experiments, involving recombinant E. coli and Bacille Calmette Guérin (BCG) strains that overexpressed Rv0079. Our observations concerning the interaction of the protein with the ribosomes are supportive of its role in regulation/inhibition of translation. We propose that the protein encoded by locus Rv0079 is a 'dormancy associated translation inhibitor' or DATIN.     

The PE/PPE multigene family codes for virulence factors and is a possible source of mycobacterial antigenic variation: perhaps more?

The PE/PPE multigene family codes for approximately 10% of the Mycobacterium tuberculosis proteome and is encoded by 176 open reading frames. These proteins possess, and have been named after, the conserved proline-glutamate (PE) or proline-proline-glutamate (PPE) motifs at their N-terminus. Their genes have a conserved structure and repeat motifs that could be a potential source of antigenic variation in M. tuberculosis. PE/PPE genes are scattered throughout the genome and PE/PPE pairs are usually encoded in bicistronic operons although this is not universally so. This gene family has evolved by specific gene duplication events. PE/PPE proteins are either secreted or localized to the cell surface. Several are thought to be virulence factors, which participate in evasion of the host immune response. This review summarizes the current knowledge about the gene family in order to better understand its biological function.