The effect of calcium and vitamin D supplementation on osteoporotic rabbit bones studied by vibrational spectroscopy

Fourier transform infrared spectroscopy is utilized to examine the effects of increased calcium, vitamin D, and combined calcium-vitamin D supplementation on osteoporotic rabbit bones with induced inflammation. The study includes different bone sites (femur, tibia, humerus, vertebral rib) in an effort to explore possible differences among the sites. We evaluate the following parameters: mineral-to-matrix ratio, carbonate content, and non-apatitic species (labile acid phosphate and labile carbonate) contribution to bone mineral. Results show that a relatively high dose of calcium or calcium with vitamin D supplementation increases the bone mineralization index significantly. On the other hand, vitamin D alone is not as effective in promoting mineralization even with high intake. Mature B-type apatite was detected for the group with calcium supplementation similar to that of aged bone. High vitamin D intake led to increased labile species concentration revealing bone formation. This is directly associated with the suppression of pro-inflammatory cytokines linked to induced inflammation. The latter is known to adversely alter bone metabolism, contributing to the aetiopathogenesis of osteoporosis. Thus, a high intake of vitamin D under inflammation-induced osteoporosis does not promote mineralization but suppresses bone resorption and restores metabolic balance.     

小叶锦鸡儿灌丛化对典型草原群落结构与生态系统功能的影响

草原灌丛化是全球干旱半干旱地区面临的重要生态问题。灌丛化对草原生态系统结构与功能的影响较为复杂, 有待于在更广泛的区域开展研究。该研究在内蒙古锡林郭勒典型草原选择轻度、中度和重度灌丛化草地, 通过群落调查, 结合植物功能性状和土壤理化性质观测, 研究了小叶锦鸡儿(Caragana microphylla)灌丛化对草原群落结构(物种多样性、功能多样性和功能群组成)和生态系统功能(初级生产力、植被和土壤养分库)的影响。结果表明: 1)不同程度灌丛化草地的物种丰富度、功能性状多样性和群落加权性状平均值差异显著, 其中, 中度灌丛化草地的物种多样性和功能多样性较高, 表明一定程度的灌丛化有利于生物多样性维持。2)重度灌丛化草地的地上净初级生产力(ANPP)显著高于轻度和中度灌丛化草地, 其原因主要是随着灌丛化程度加剧, 群落内一/二年生草本植物显著增加, 而多年生禾草和多年生杂类草显著减少。三个灌丛化草地的植被叶片和土壤碳、氮库差异均不显著。3)灌丛化对草原生态系统功能包括ANPP、植被和土壤养分库均没有直接的影响, 而是通过影响功能群组成、土壤理化性质和功能多样性, 间接地影响生态系统功能; 灌丛化导致功能群发生替代和土壤旱碱化是最重要的生物和非生物因素。     

Subunit polypeptide composition of rubisco and the origin of allopolyploid Arabidopsis suecica (Brassicaceae)

The polypeptide composition of the large and small subunits of Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) from Arabidopsis thaliana, A. suecica and Cardaminopsis arenosa have been studied by IEF (isoelectric focusing) analysis. The putative recent alopolyploid origin of A. suecica is supported. The chloroplast encoded large subunits served to identify solely A. thaliana as the maternal parent whereas the nuclear encoded small subunits indicate C. arenosa as the paternal species.     

The chemical compound ‘Heatin’ stimulates hypocotyl elongation and interferes with the Arabidopsis NIT1-subfamily of nitrilases

Temperature passively affects biological processes involved in plant growth. Therefore, it is challenging to study the dedicated temperature signalling pathways that orchestrate thermomorphogenesis, a suite of elongation growth-based adaptations that enhance leaf-cooling capacity. We screened a chemical library for compounds that restored hypocotyl elongation in the pif4-2–deficient mutant background at warm temperature conditions in Arabidopsis thaliana to identify modulators of thermomorphogenesis. The small aromatic compound ‘Heatin’, containing 1-iminomethyl-2-naphthol as a pharmacophore, was selected as an enhancer of elongation growth. We show that ARABIDOPSIS ALDEHYDE OXIDASES redundantly contribute to Heatin-mediated hypocotyl elongation. Following a chemical proteomics approach, the members of the NITRILASE1-subfamily of auxin biosynthesis enzymes were identified among the molecular targets of Heatin. Our data reveal that nitrilases are involved in promotion of hypocotyl elongation in response to high temperature and Heatin-mediated hypocotyl elongation requires the NITRILASE1-subfamily members, NIT1 and NIT2. Heatin inhibits NIT1-subfamily enzymatic activity in vitro and the application of Heatin accordingly results in the accumulation of NIT1-subfamily substrate indole-3-acetonitrile in vivo. However, levels of the NIT1-subfamily product, bioactive auxin (indole-3-acetic acid), were also significantly increased. It is likely that the stimulation of hypocotyl elongation by Heatin might be independent of its observed interaction with NITRILASE1-subfamily members. However, nitrilases may contribute to the Heatin response by stimulating indole-3-acetic acid biosynthesis in an indirect way. Heatin and its functional analogues present novel chemical entities for studying auxin biology.     

Molecular phylogeny,pigment composition,toxicology and life history of Pseudochattonella cf. verruculosa (Class Dictyochophyceae) from Wellington Harbour,New Zealand

Pseudochattonella verruculosa is a heterokont flagellate and has frequently been found associated with multi-species harmful algal blooms in Wellington Harbour. In this study the partial sequences of the nuclear encoded LSU rDNA and the large subunit of ribulose bisphosphate carboxylase (rbcL) of Pseudochattonella isolated from Wellington Harbour indicate that it is similar to P. verruculosa, while sequences of mitochondrial encoded COI, are similar to those of Pseudochattonella farcimen. As with P. farcimen, the Wellington Pseudochattonella lacked violaxanthin, lutein and anteroxanthin, three pigments detected only in P. verruculosa. The Wellington isolate also contains zeaxanthin which is absent in P. farcimen. Among all Pseudochattonella, cells of the Wellington isolate are the most variable in terms of both size and shape. Mucocysts of the Wellington Pseudochattonella also have the greatest degree of variation – from small, ‘bullet’-shape to large oval, oblong or ‘sausage’-like. In the sexual reproduction phase two gametes of the Wellington isolate fuse to form a zygote which gives rise to a large multi-nucleate cell. At times two or more of these large multi-nucleate cells fuse further to form a ‘massive’, plasmodium-like aggregate (up to 200 μm long). Positive feeding and toxicity tests on rotifers confirmed that the Wellington Pseudochattonella is cytotoxic and probably also contributed to the May 2010 fish kills. As molecular phylogenies do not conclusively support the separation of the Wellington Harbour Pseudochattonella from P. verruculosa or P. farcimen, it is tentatively named as Pseudochattonella cf. verruculosa.     

Community composition has greater impact on the functioning of marine phytoplankton communities than ocean acidification

Ecosystem functioning is simultaneously affected by changes in community composition and environmental change such as increasing atmospheric carbon dioxide (CO₂) and subsequent ocean acidification. However, it largely remains uncertain how the effects of these factors compare to each other. Addressing this question, we experimentally tested the hypothesis that initial community composition and elevated CO₂ are equally important to the regulation of phytoplankton biomass. We full‐factorially exposed three compositionally different marine phytoplankton communities to two different CO₂ levels and examined the effects and relative importance (ω²) of the two factors and their interaction on phytoplankton biomass at bloom peak. The results showed that initial community composition had a significantly greater impact than elevated CO₂ on phytoplankton biomass, which varied largely among communities. We suggest that the different initial ratios between cyanobacteria, diatoms, and dinoflagellates might be the key for the varying competitive and thus functional outcome among communities. Furthermore, the results showed that depending on initial community composition elevated CO₂ selected for larger sized diatoms, which led to increased total phytoplankton biomass. This study highlights the relevance of initial community composition, which strongly drives the functional outcome, when assessing impacts of climate change on ecosystem functioning. In particular, the increase in phytoplankton biomass driven by the gain of larger sized diatoms in response to elevated CO₂ potentially has strong implications for nutrient cycling and carbon export in future oceans.     

Chemically-Synthesized Gene Encoding Modified Human Superoxpde Dismutase: Its Construction,Expression and Properties of the Product

The gene encoding modified human superoxide dismutax (h-SOD) with 153 amino acid residues was constructed by chemical synthesis using the phosphoramidite method. The gene was designed so as to use bacterial codons for expression in prokaryotes and to introduce several unique restriction sites for further mutagenesis by the cassette exchange method. The distance between Shine-Dalgarno sequence and initiation codon was adjusted to maximum expression by using synthesized oligonucleotide. In addition, Cys 6 of h-SOD was changed to Ala to improve instability of native h-SOD.

Synthesized structural gene of h-SOD was expressed in E. coli after induction of isopropyl β-D-thiogalactoside by inserting the gene into the expression vector pKK223–3 having tac promoter. The gene that has 10 base pairs between Shine-Dalgarno sequence and initiation codøn showed the most efficient expression. The gene produced three active SOD isomers as revealed by chromatofocusing.

The main isomer was purified to homogeneity and characterized. The h-SOD-Ala⁶ showed similar properties to those of native h-SOD with respect to molecular weight, subunit structure, absorption spectrum. but the modified SOD was more resistant to heat denaturation than was native h-SOD; half-denaturing temperature was shifted by 10°C. Thus. the exchange of Cys 6 to Ala of h-SOD increased a stability of the enzyme.