Novel chitin/nanosilica composite scaffolds for bone tissue engineering applications

Biopolymers like chitin are widely investigated as scaffolds in bone tissue engineering. Its properties like biocompatibility, biodegradability, non-toxicity, wound healing ability, antibacterial activity, hemostatic property, etc., are widely known. However, these materials are not much bioactive. Addition of material like silica can improve the bioactivity and biocompatibility of chitin. In this work, chitin composite scaffolds containing nanosilica were prepared using chitin hydrogel and their bioactivity, swelling ability and cytotoxicity was analyzed in vitro. These scaffolds were found to be bioactive in simulated body fluid (SBF) and biocompatible when tested with MG 63 cell line. These results suggest that chitin/nanosilica composite scaffolds can be useful for bone tissue engineering applications.     

A spatially explicit data-driven approach to assess the effect of agricultural land occupation on species groups

Purpose

Change of vegetation cover and increased land use intensity, particularly for agricultural use, can affect species richness. Within life cycle impact assessment, methods to assess impacts of land use on a global scale are still in need of development. In this work, we present a spatially explicit data-driven approach to characterize the effect of agricultural land occupation on different species groups.

Methods

We derived characterization factors for the direct impact of agricultural land occupation on relative species richness. Our method identifies potential differences in impacts for cultivation of different crop types, on different species groups, and in different world regions. Using empirical species richness data gathered via an extensive literature search, characterization factors were calculated for four crop groups (oil palm, low crops, Pooideae, and Panicoideae), four species groups (arthropods, birds, mammals, and vascular plants), and six biomes.

Results and discussion

Analysis of the collected data showed that vascular plant richness is more sensitive than the species richness of arthropods to agricultural land occupation. Regarding the differences between world regions, the impact of agricultural land use was lower in boreal forests/taiga than in temperate and tropical regions. The impact of oil palm plantations was found to be larger than that of Pooideae croplands, although we cannot rule out that this difference is influenced by the spatial difference between the oil palm- and Pooideae-growing regions as well. Analysis of a subset of data showed that the impact of conventional farming was larger than the impact of low-input farming.

Conclusions

The impact of land occupation on relative species richness depends on the taxonomic groups considered, the climatic region, and farm management. The influence of crop type, however, was found to be of less importance.     

Curative effect of Semecarpus anacardium Linn. nut milk extract against adjuvant arthritis -- with special reference to bone metabolism

Localised bone loss in the form of bone erosions and peri-articular osteopenia constitutes an important criteria for the diagnosis of rheumatoid arthritis. In the present study, the effect of Semecarpus anacardium Linn. nut milk extract (SA) on the metabolism of bone turn over has been studied by analyzing various markers of bone turnover and by histological and radiological analysis of the joints in adjuvant arthritis in rats. Arthritis was induced in rats by injecting Freund's complete adjuvant containing 10mg of heat killed mycobacterium tuberculosis in 1 ml paraffin oil (0.1 ml) into the left hind paw of the rat intradermally. After 14 days of induction, SA (150 mg/kg body weight/day) was administered orally by gastric intubations for 14 days. SA significantly reverted the alterations in the bone turnover observed in arthritic animals by modulating the levels of calcium, phosphorus and the activities of the enzymes names tartrate resistant acid phosphatase, acid phosphatase and alkaline phosphatase. The drug increased the bone weights that were found to be decreased during arthritis. Protective effect of SA was also observed by the decrease in the levels and expression of tumour necrosis factor alpha (TNF-alpha) as well as the histopathological and radiological observations. From all these observations it can be concluded that SA possesses strong anti-arthritic property by regulating bone turnover.     

Pin1 Promotes Transforming Growth Factor-��-induced Migration and Invasion

Transforming growth factor-β (TGF-β) regulates a wide variety of biological activities. It induces potent growth-inhibitory responses in normal cells but promotes migration and invasion of cancer cells. Smads mediate the TGF-β responses. TGF-β binding to the cell surface receptors leads to the phosphorylation of Smad2/3 in their C terminus as well as in the proline-rich linker region. The serine/threonine phosphorylation sites in the linker region are followed by the proline residue. Pin1, a peptidyl-prolyl cis/trans isomerase, recognizes phosphorylated serine/threonine-proline motifs. Here we show that Smad2/3 interacts with Pin1 in a TGF-β-dependent manner. We further show that the phosphorylated threonine 179-proline motif in the Smad3 linker region is the major binding site for Pin1. Although epidermal growth factor also induces phosphorylation of threonine 179 and other residues in the Smad3 linker region the same as TGF-β, Pin1 is unable to bind to the epidermal growth factor-stimulated Smad3. Further analysis suggests that phosphorylation of Smad3 in the C terminus is necessary for the interaction with Pin1. Depletion of Pin1 by small hairpin RNA does not significantly affect TGF-β-induced growth-inhibitory responses and a number of TGF-β/Smad target genes analyzed. In contrast, knockdown of Pin1 in human PC3 prostate cancer cells strongly inhibited TGF-β-mediated migration and invasion. Accordingly, TGF-β induction of N-cadherin, which plays an important role in migration and invasion, is markedly reduced when Pin1 is depleted in PC3 cells. Because Pin1 is overexpressed in many cancers, our findings highlight the importance of Pin1 in TGF-β-induced migration and invasion of cancer cells.     

Sharpening gene editing toolbox in Arabidopsis for plants

Journal of Plant Biochemistry and Biotechnology - Arabidopsis thaliana is considered as an indispensable model system across various disciplines of modern plant biology. The short life cycle, well...     

Comparative Analysis of DNA Word Abundances in Four Yeast Genomes Using a Novel Statistical Background Model

Previous studies have shown that the identification and analysis of both abundant and rare k-mers or “DNA words of length k” in genomic sequences using suitable statistical background models can reveal biologically significant sequence elements. Other studies have investigated the uni/multimodal distribution of k-mer abundances or “k-mer spectra” in different DNA sequences. However, the existing background models are affected to varying extents by compositional bias. Moreover, the distribution of k-mer abundances in the context of related genomes has not been studied previously. Here, we present a novel statistical background model for calculating k-mer enrichment in DNA sequences based on the average of the frequencies of the two (k-1) mers for each k-mer. Comparison of our null model with the commonly used ones, including Markov models of different orders and the single mismatch model, shows that our method is more robust to compositional AT-rich bias and detects many additional, repeat-poor over-abundant k-mers that are biologically meaningful. Analysis of overrepresented genomic k-mers (4≤k≤16) from four yeast species using this model showed that the fraction of overrepresented DNA words falls linearly as k increases; however, a significant number of overabundant k-mers exists at higher values of k. Finally, comparative analysis of k-mer abundance scores across four yeast species revealed a mixture of unimodal and multimodal spectra for the various genomic sub-regions analyzed.