Regulation of the G2/M phase of the cell cycle by sperm associated antigen 8 (SPAG8) protein

Sperm associated antigen 8 (SPAG8), a testis‐specific protein produced during male germ cell differentiation, was isolated from a human testis expression library using antibodies found in the serum obtained from an infertile woman. It was found to have a close functional relationship with microtubules. In this study, we generated a stably expressing SPAG8 CHO‐K1 cell line. Immunofluorescence confocal microscopy showed that SPAG8 was concentrated at the microtubule‐organizing center (MTOC) during prophase. As the cells progressed into metaphase, it co‐localized with α‐tubulin on the spindle. In anaphase, it was detected on both astral microtubules and mid‐zone. Following cytokinesis, SPAG8 resumed its localization on the MTOC. Meanwhile, flow cytometry analysis found that SPAG8 prolonged the G2/M phase of CHO‐K1 cells stably expressing SPAG8. Furthermore, 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay showed that SPAG8 inhibited the proliferation of the stable cells. SPAG8 might be involved in the regulation of cell cycle by changing the phosphorylation level of Tyr15 on cdc2. These results suggest that SPAG8 might play a role in cell division during spermatogenesis. Copyright © 2009 John Wiley & Sons, Ltd.     

Catalytic removal of sulfide by an immobilized sulfide-oxidase bioreactor

A bioreactor packed with chitosan immobilized sulfide-oxidase from Streptomyces species LD048 was developed to treat a liquid stream of sulfide. The inoculation system was composed of glass with a 0.7 L working volume and enzyme activity of 2 mmol S g^?1 carrier. The sulfide removal efficiency was almost 100% when the volumetric loading was increased up to 3.9 mmol S L^?1 h^?1 at a space velocity of 18 h^?1. The maximal elimination capacity was 22.1 mmol S L^?1 h^?1 with a space velocity of 72 h^?1. When the aeration was increased from 0.05 to 0.1 L min^?1, the average removal efficiency improved from 81% to 94%. A removal efficiency of 90% was obtained after 15 days of operation with a load rate of 8.9 mmol S L^?1 h^?1 and a space velocity of 14.28 h^?1. An operational equation based on the ideal plug flow bioreactor and the Michaelis–Menten model predicted the performance of this bioreactor.     

5-Methyltetrahydrofolate is photosensitive in the presence of riboflavin.

5-Methyltetrahydrofolate (5MTHF) is the main form of folate in human plasma, and an important vitamin for human health. Photodegradation of folates may have played a role in the development of different human skin colours. 5MTHF can be degraded directly by exposure to ultraviolet radiation or by exposure to visible light in the presence of endogenous sensitizers like riboflavin (RF). These photochemical reactions were studied by absorption spectroscopy. While 5MTHF is stable under UV and visible light exposure in pure aqueous media, it is quickly degraded in the presence of RF during UVA and blue light exposure. The degradation of 5MTHF is dependent on the concentration of RF, but not on the concentration of 5MTHF itself. UVA and blue light gave similar reactions. Further investigations are necessary to evaluate the consequences of large light exposures in vivo in humans. Our findings should be taken into the ongoing discussion about the development of human skin colours. Due to the presence of RF in human blood, folate can be significantly degraded during prolonged or intense blue light exposure. Thus, a dark skin colour may be favourable for prevention of folate degradation under high solar fluence rates, such as in equatorial areas.     

Secondary Metabolites from Aspergillus fumigatus,an Endophytic Fungus from the Liverwort Heteroscyphus tener (Steph.) Schiffn.

Three new metabolites, asperfumigatin ( 1 ), isochaetominine ( 10 ), and 8′‐O‐methylasterric acid ( 21 ), together with nineteen known compounds, were obtained from the culture of Aspergillus fumigatus, an endophytic fungus from the Chinese liverwort Heteroscyphus tener (Steph.) Schiffn. Their structures were established by extensive analysis of the spectroscopic data. The absolute configurations of 1 and 10 were determined by analysis of their respective CD spectra. Cytotoxicity of these isolates against four human cancer cell lines was also determined.     

New Labdane Diterpenes and Their Glycoside Derivatives from the Roots of Isodon adenantha

Two new labdane‐type diterpenes (adenanthic acids A and B; 1 and 2 , resp.) and three new labdane diterpene glycosides (adenanthosides A–C; 3 – 5 , resp.) were isolated from the roots of Isodon adenantha, together with 23 known constituents including seven diterpenoids ( 6 – 12 ), eight triterpenoids ( 13 – 20 ), one lignan glycoside ( 21 ), six steroids ( 22 – 27 ), and one ceramide ( 28 ). Their structures were elucidated by spectroscopic methods including extensive 2D‐NMR techniques. Cytotoxicity and antibacterial activities of the samples were measured by the MTT method and the filter paper disc agar diffusion method. But none of them showed significant activities.     

The alteration in the architecture of a T‐DNA insertion rice mutant osmtd1 is caused by up‐regulation of MicroRNA156f

Plant architecture is an important factor for crop production. Some members of microRNA156 (miR156) and their target genes SQUAMOSA Promoter‐Binding Protein‐Like (SPL) were identified to play essential roles in the establishment of plant architecture. However, the roles and regulation of miR156 is not well understood yet. Here, we identified a T‐DNA insertion mutant Osmtd1 (Oryza sativa multi‐tillering and dwarf mutant). Osmtd1 produced more tillers and displayed short stature phenotype. We determined that the dramatic morphological changes were caused by a single T‐DNA insertion in Osmtd1. Further analysis revealed that the T‐DNA insertion was located in the gene Os08g34258 encoding a putative inhibitor I family protein. Os08g34258 was knocked out and OsmiR156f was significantly upregulated in Osmtd1. Overexpression of Os08g34258 in Osmtd1 complemented the defects of the mutant architecture, while overexpression of OsmiR156f in wild‐type rice phenocopied Osmtd1. We showed that the expression of OsSPL3, OsSPL12, and OsSPL14 were significantly downregulated in Osmtd1 or OsmiR156f overexpressed lines, indicating that OsSPL3, OsSPL12, and OsSPL14 were possibly direct target genes of OsmiR156f. Our results suggested that OsmiR156f controlled plant architecture by mediating plant stature and tiller outgrowth and may be regulated by an unknown protease inhibitor I family protein.