Extraction and Analysis of Available Boron Isotopes in Soil Using Multicollector Inductively Coupled Plasma Mass Spectrometry.

As a result of the important roles of boron (B) in the growth of plants, the uptake of B by plants is dependent upon the existing form and content of available B in soil, which can bring about the local cycle of B isotope equilibrium. A method using water-heating extraction combined with three-step ion-exchange chromatography was developed for the extraction and isotopic analysis of available B in soil. The extraction efficiency and fractionation of B isotopic composition in the procedure were investigated. The results showed that, in the upper layers of soils, the change of δ11B values was opposite that of the mass concentration and a similar variation between δ11B and content occurred in the lower layers. The isotope of available B in soil can create a featured isotopic signature to further understand the geochemical details related to the soil properties and molecular mechanism of B uptake in plants.

Differentiation analysis of boron isotopic fractionation in different forms within plant organ samples.

As a critical micronutrient, boron (B) plays an important role in plant growth and embryonic development. To further understand the effects of B uptake, transportation and isotopic fractionation, the contents and isotopic compositions of hydro-soluble B in the sap and structural B fixed in the cell within individual plant tissues were investigated. The B isotope ratio was determined by multi-collector inductively coupled plasma mass spectrometry. The δ11B values in hydro-soluble and structural B in the investigated plant samples ranged from -1.57‰ to +11.30‰ and from +6.57‰ to +16.64‰, respectively. Different fractionation factors of the B isotopes, in the range of 0.9954-1.0150, were observed in these samples, indicating that in most plant tissues, the heavy isotope (11B) was preferentially enriched in structural B, which was fixed into the cell. However, there was a reversal in the fractionation of B isotopic compositions in the fruit samples compared with the other plant tissue samples. It is more powerful to examine the molecular mechanisms of B transport, uptake and utilization than the use of limited plant organ samples containing a mixture of hydro-soluble and structural B within different intra-plant compartments and in inter-plant interactions. These isotopic shifts, which may be used as important isotopic indicators, contribute to the surface processes interactions in the plant-soil system and the knowledge of the molecular mechanisms of B in the uptake and absorption by different plant species in nature.

Separation and Analysis of Boron Isotope in High Plant by Thermal Ionization Mass Spectrometry.

Knowledge of boron and its isotope in plants is useful to better understand the transposition and translocation of boron within plant, the geochemical behavior in the interface between soil and plant, and the biogeochemical cycle of boron. It is critical to develop a useful method to separate boron from the plant for the geochemical application of boron and its isotope. A method was developed for the extraction of boron in plant sample, whose isotope was determined by thermal ionization mass spectrometry. The results indicated that this method of dry ashing coupled with two-step ion-exchange chromatography is powerful for the separation of boron in plant sample with large amounts of organic matters completely. The ratios of boron isotope composition in those plant tissue samples ranged from -19.45‰ to +28.13‰ (total range: 47.58‰) with a mean value of 2.61 ± 11.76‰ SD. The stem and root isotopic compositions were lower than those in flower and leaf. The molecular mechanism of boron isotope may be responsible for the observed variation of boron isotopic composition and are considered as a useful tool for the better understanding of boron cycling process in the environment and for the signature of living systems.

Atomic force bio-analytics of polymerization and aggregation of phycoerythrin-conjugated immunoglobulin G molecules.

While bio-labeled immunoglobulin (IgG) or antibodies are extensively used in imaging studies and therapeutic modality, there have been no reports describing atomic force microscopy (AFM) micrographs of these labeled IgG molecules. Here, AFM studies of phycoerythrin (PE)-conjugated IgG were undertaken to examine whether PE conjugation induced conformational changes or molecular interaction, and subsequently resulted in an alteration in nano-structures of PE-conjugated IgG complex. Once immobilized on mica, single PE-conjugated IgG molecule exhibited globular shape with approximately 60 microns in diameter and 5 microns in height. PE-conjugated IgG were able to form monomers, spindle-like trimers, and hexamers that developed through an end-end connection of two trimers, after they were continuously immobilized on mica. Interestingly, these multimers could aggregate in different directions to form circular monolayers with a highly dense core of PE-conjugated IgG polymers. The formation of these well-organized polymers and aggregates of PE-conjugated IgG may be attributed to the PE conjugation as well as the air-liquid tension on subtract. These findings may help to understand the nano-structures of bio-labeled IgG or antibodies, and facilitate the potential use of PE-conjugated antibodies as markers or immunosensers for AFM bio-analytics of biomolecules in cells and membranes.