Metabolism of Fructooligosaccharides by Lactobacillus paracasei 1195

Fermentation of fructooligosaccharides (FOS) and other oligosaccharides has been suggested to be an important property for the selection of bacterial strains used as probiotics. However, little information is available on FOS transport and metabolism by lactic acid bacteria and other probiotic bacteria. The objectives of this research were to identify and characterize the FOS transport system of Lactobacillus paracasei 1195. Radiolabeled FOS was synthesized enzymatically from [³H]sucrose and purified by column and thin-layer chromatography, yielding three main products: glucose (G) α-1,2 linked to two, three, or four fructose (F) units (GF₂, GF₃, and GF₄, respectively). FOS hydrolysis activity was detected only in cell extracts prepared from FOS- or sucrose-grown cells and was absent in cell supernatants, indicating that transport must precede hydrolysis. FOS transport assays revealed that the uptake of GF₂ and GF₃ was rapid, whereas little GF₄ uptake occurred. Competition experiments showed that glucose, fructose, and sucrose reduced FOS uptake but that other mono-, di-, and trisaccharides were less inhibitory. When cells were treated with sodium fluoride, iodoacetic acid, or other metabolic inhibitors, FOS transport rates were reduced by up to 60%; however, ionophores that abolished the proton motive force only slightly decreased FOS transport. In contrast, uptake was inhibited by ortho-vanadate, an inhibitor of ATP-binding cassette transport systems. De-energized cells had low intracellular ATP concentrations and had a reduced capacity to accumulate FOS. These results suggest that FOS transport in L. paracasei 1195 is mediated by an ATP-dependent transport system having specificity for a narrow range of substrates.     

The Occurrence and Age Distribution of Harris Lines in Turkey

Harris lines are widely accepted as indicators of physiological stress and provide valuable data for determining the extent and nature of the physiological stress factors acting on a human community. Traditionally, Harris lines are studied in skeletal populations. In the study reported here, data were collected on living children to eventually clarify if stress is basically chronic or acute in nature, if it has a greater impact on children or adults, and if it is correlated with increased rates of mortality. The existence of Harris lines was determined in a sample of 400 children, 210 males and 190 females, randomly selected from those under examination in the radiology services of hospitals. Radiological analysis was used to analyze Harris lines. The age of Harris line formation and variations in the number of lines with age were established to determine at which age the densest line population was present. For this sample, the formation of Harris lines is around 2–3 years of age, in agreement with published literature. It should be taken into consideration that Harris lines are the end result of multiple factors, rather than a single stress factor, and are influenced by an individual’s immune system and resistance to stress.     

Redesigning the bean seed germination experiment: an activity sheet suggestion

Abstract

Germinating a seed is presumably the first experiment made by a child in his life. So, it has an important place both in child’s scientific experience and understanding. Despite the significance of the experiment, the literature indicates that students possess various misconceptions related to the concepts of seed and seed germination. So, it is thought that this experiment should be focused on in more detail. The purpose of this paper is presenting a proper activity sheet for middle school students to perform this experiment effectively. Science teachers might follow it as an instructional tool in their courses. Thus it is expected to assist students explore the factors which are affective on bean seed germination.     

Histone acetyltransferases and histone deacetyl transferases play crucial role during oogenesis and early embryo development

Dynamic epigenetic regulation is critical for proper oogenesis and early embryo development. During oogenesis, fully grown germinal vesicle oocytes develop to mature Metaphase II oocytes which are ready for fertilization. Fertilized oocyte proliferates mitotically until blastocyst formation and the process is called early embryo development. Throughout oogenesis and early embryo development, spatio-temporal gene expression takes place, and this dynamic gene expression is controlled with the aid of epigenetics. Epigenetic means that gene expression can be altered without changing DNA itself. Epigenome is regulated through DNA methylation and histone modifications. While DNA methylation generally ends up with repression of gene expression, histone modifications can result in expression or repression depending on type of modification, type of histone protein and its specific residue. One of the modifications is histone acetylation which generally ends up with gene expression. Histone acetylation occurs through the addition of acetyl group onto amino terminal of the core histone proteins by histone acetyltransferases (HATs). Contrarily, histone deacetylation is associated with repression of gene expression, and it is catalyzed by histone deacetylases (HDACs). This review article focuses on what is known about alterations in the expression of HATs and HDACs and emphasizes importance of HATs and HDACs during oogenesis and early embryo development.     

Augmentation of ADAMTS9 gene expression by IL‐1β is reversed by NFκB and MAPK inhibitors,but not PI3 kinase inhibitors

The pathways involved in the regulation of a disintegrin and metalloproteinase with thrombospondin motifs 9 (ADAMTS9) expression have not yet been elucidated. Therefore, the aim of this study was to investigate the involvement of nuclear factor‐κB (NF‐κB), mitogen activated protein kinases (MAPK) and Phosphatidylinositol 3‐kinase (PI3 kinase) in ADAMTS9 gene regulation, with special focus on the involvement of NF‐κB in IL‐1β‐induced ADAMTS9 expression. The OUMS‐27 chondrosarcoma cells were exposed to IL‐1β. They were pretreated with 20 μM PD98059 (specific inhibitor of p44/42 kinase), 10 μM SB203580 (specific inhibitor of p38 kinase), 20 μM SB600125 (MAPK inhibitor), and 1 μM Wortmannin and 10 μM LY294002 (specific inhibitors of PI3 kinase) for 30 min and subsequently incubated with IL‐1β. For the effects of NF‐κB and IκB inhibitors, cells were pretreated with curcumin or BAY117085 for 30 min and subsequently incubated with IL‐1β. BAY117085 and different concentrations of curcumin were applied to the cells just after the first experiment to determine their concentration effect on ADAMTS9 gene expression. After total RNA was extracted, they were reversely transcribed with random primers and then real‐time polymerase chain reaction (PCR) was performed on cDNA samples. There was a significant difference between control and stimulated cells in terms of ADAMTS9/β‐actin ratio. Wortmannin and LY294002 did not have any repressive effect on the OUMS‐27 whereas SB203580 and SP600125 were found to decrease the expression of ADAMTS9 gene. BAY 117085 and curcumin, which are two NF‐κB inhibitors, led to a decrease in the ratio of ADAMTS9/β‐actin. As a conclusion, the pathways MAPK and NF‐κB were thought to be responsible pathways for the induction of ADAMTS9 gene. Copyright © 2012 John Wiley & Sons, Ltd.