Regional analysis of potential polychlorinated biphenyl degrading bacterial strains from China

AbstractPolychlorinated biphenyls (PCBs), the chlorinated derivatives of biphenyl, are one of the most prevalent, highly toxic and persistent groups of contaminants in the environment. The objective of this study was to investigate the biodegradation of PCBs in northeastern (Heilongjiang Province), northern (Shanxi Province) and eastern China (Shanghai municipality). From these areas, nine soil samples were screened for PCB-degrading bacteria using a functional complementarity method. The genomic 16S rDNA locus was amplified and the products were sequenced to identify the bacterial genera. Seven Pseudomonas strains were selected to compare the capacity of bacteria from different regions to degrade biphenyl by HPLC. Compared to the biphenyl content in controls of 100%, the biphenyl content went down to 3.7% for strain P9-324, 36.3% for P2-11, and 20.0% for the other five strains. These results indicate that a longer processing time led to more degradation of biphenyl. PCB-degrading bacterial strains are distributed differently in different regions of China

Systematic Analysis of Pericarp Starch Accumulation and Degradation during Wheat Caryopsis Development.

Although wheat (Triticum aestivum L.) pericarp starch granule (PSG) has been well-studied, our knowledge of its features and mechanism of accumulation and degradation during pericarp growth is poor. In the present study, developing wheat caryopses were collected and starch granules were extracted from their pericarp to investigate the morphological and structural characteristics of PSGs using microscopy, X-ray diffraction and Fourier transform infrared spectroscopy techniques. Relative gene expression levels of ADP-glucose pyrophosphorylase (APGase), granule-bound starch synthase II (GBSS II), and α-amylase (AMY) were quantified by quantitative real-time polymerase chain reaction. PSGs presented as single or multiple starch granules and were synthesized both in the amyloplast and chloroplast in the pericarp. PSG degradation occurred in the mesocarp, beginning at 6 days after anthesis. Amylose contents in PSGs were lower and relative degrees of crystallinity were higher at later stages of development than at earlier stages. Short-range ordered structures in the external regions of PSGs showed no differences in the developing pericarp. When hydrolyzed by α-amylase, PSGs at various developmental stages showed high degrees of enzymolysis. Expression levels of AGPase, GBSS II, and AMY were closely related to starch synthesis and degradation. These results help elucidate the mechanisms of accumulation and degradation as well as the functions of PSG during wheat caryopsis development

Effect of nitrogen fertilizer on distribution of starch granules in different regions of wheat endosperm

This study provided visual evidence of a nitrogen effect on starch granules (SGs) in wheat endosperm. Winter wheat (Titicum aestivum L.) cultivar Xumai 30 was cultured under no nitrogen (control) and 240 kg ha− 1 of nitrogen applied at the booting stage. The number, morphology, and size of A- and B-type SGs in subaleurone of dorsal endosperm (SDE), center of dorsal endosperm (CDE), modified aleurone (MA), subaleurone of ventral endosperm (SVE), and center of ventral endosperm (CVE) were observed under light and electron microscopes. (1) The distribution of SGs in SDE was similar to that in SVE, the distributions of SGs in CDE and CVE were similar, but the distribution of SGs in MA was different from those in the other four endosperm regions. The number of SGs in the five endosperm regions was in the order SDE > CDE > SVE > CVE > MA. (2) Nitrogen increased the number of A- and B-type SGs in SDE and SVE. Nitrogen also increased the number of B-type SGs but decreased the number of A-type SGs in CDE and CVE. Nitrogen decreased the numbers of A-type and B-type SGs in MA. The results suggest that increased N fertilizer application mainly increased the numbers of small SGs and decreased the numbers of large SGs, but that the results varied in different regions of the wheat endosperm

Research progress on the bulb expansion and starch enrichment in taro (Colocasia esculenta (L). Schott)

Background Taro is an important potato crop, which can be used as food, vegetable, feed, and industrial raw material. The yield and quality of taro are primarily determined by the expansion degree of taro bulb and the filling condition of starch, whereas the expansion of taro bulb is a complex biological process. However, little information is reviewed on the research progress of bulb expansion and starch enrichment in taro. Methodology PubMed, Web of Science, and the China National Knowledge Infrastructure databases were searched for relevant articles. After removing duplicate articles and articles with little relevance, 73 articles were selected for review. Results This article introduces the formation and development of taro bulb for workers engaged in taro research. The content includes the process of amyloplast formation at the cytological level and changes in bulb expansion and starch enrichment at physiological levels, which involve endogenous hormones and key enzyme genes for starch synthesis. The effects of environment and cultivation methods on taro bulb expansion were also reviewed. Conclusions Future research directions and research focus about the development of taro bulb were proposed. Limited research has been conducted on the physiological mechanism and hormone regulatory pathway of taro growth and development, taro bulb expansion, key gene expression, and starch enrichment. Therefore, the abovementioned research will become the key research direction in the future

Fluorescence microscopy images of transverse sections of wheat caryopsis at 2 DAA (A), 6 DAA (E), 10 DAA (I), and 20 DAA (M).

<p>Light microscopy images of wheat pericarp (<b>B–D, F–H, J–L,</b> and <b>N–P</b>): epicarp (<b>B</b>), mesocarp (<b>C</b>), and mesocarp near the vascular bundle (<b>D</b>) at 2 DAA; mesocarp (<b>F, G</b>) and mesocarp near the vascular bundle (<b>H</b>) at 6 DAA; epicarp (<b>J</b>), mesocarp (<b>K</b>), and mesocarp near the vascular bundle (<b>L</b>) at 10 DAA; epicarp (<b>N</b>) and mesocarp near the vascular bundle (<b>O</b> and <b>P</b>) at 20 DAA. Black arrowheads in <b>C</b> and <b>E, I</b> indicate new cell walls and apoptotic cavities. The black box in <b>K</b> indicates degraded starch granules in the mesocarp. CC, cross cell; CMC, cracked mesocarp cell; En, endosperm; Ep, epicarp; Me, mesocarp; Pe, pericarp; SG, starch granule. Scale bars: 1 mm (<b>A, E, I,</b> and <b>M</b>) and 20 μm (<b>B–D, F–H, J–L,</b> and <b>N–P</b>).</p

XRD (A) and ATR-FTIR (B) spectra of PSGs at 2, 6, 10, and 20 DAA.

<p>XRD (A) and ATR-FTIR (B) spectra of PSGs at 2, 6, 10, and 20 DAA.</p

Total starch (A) and soluble sugar (B) contents of wheat pericarp at 2, 6, 10, and 20 DAA.

<p>Data represent the means of three replicates, and standard deviations are shown as vertical bars. Significant differences (P ≤ 0.05) between different DAA values are indicated by lowercase letters.</p

Fluorescence (A) and transmission electron microscope (B–I) images.

<p>Transverse section of wheat caryopsis at 6 DAA (<b>A</b>); higher magnification of the white box 1 in <b>A</b> at 6 DAA (<b>B</b>); higher magnification of white box 1 in <b>A</b> at 20 DAA (<b>C</b>); higher magnification of white box 2 in <b>A</b> at 6 DAA (<b>D, E</b>); higher magnification of white box 2 in <b>A</b> at 20 DAA (<b>F</b>); higher magnification of white box 3 in <b>A</b> at 6 DAA (<b>G, H</b>); higher magnification of white box 3 in <b>A</b> at 20 DAA (<b>I</b>). CC, cross cell; Ch, chloroplast; MSG, multiple starch granule; En, endosperm; MCVB, mesocarp cell near vascular bundle; Pe, pericarp; SG, starch granule; SSG, single starch granule; TC, tube cell; VB, vascular bundle. Scale bars: 1 mm (<b>A</b>) and 5 μm (<b>B–I</b>).</p

Relative gene expression levels of the genes <i>AGPase</i> (A), <i>GBSS II</i> (B) and <i>AMY</i> (C) in wheat pericarp at 2, 6, 10, and 20 DAA.

<p>Significant differences (P ≤ 0.05) between different DAAs are indicated by lowercase letters.</p