Impairment of GABAergic neurotransmitter system in the amygdala of young rats after 4-week zinc deprivation

On the basis of the evidence that the excitability of hippocampal glutamatergic neurotransmitter system is enhanced by dietary zinc deficiency, the response of amygdalar neurotransmitter system was checked in young rats fed a zinc-deficient diet for 4 weeks. Extracellular zinc concentration in the amygdala, which was measured by the in vivo microdialysis, was almost the same as that in the hippocampus and decreased by zinc deficiency. Extracellular zinc concentration in the amygdala was increased both in the control and zinc-deficient rats by stimulation with 100 mM KCl, suggesting that the increase in extracellular zinc in the amygdala, as well as that in the hippocampus, is linked with neuronal depolarization. In amygdalar extracellular fluid, the basal glutamate concentration was not significantly different between the control and zinc-deficient rats and was increased to almost the same extent between them by stimulation with 100 mM KCl, unlike more increase in extracellular glutamate concentration in the hippocampus in zinc deficiency. On the other hand, the basal GABA concentration in the amygdalar extracellular fluid was significantly lower in zinc-deficient rats and was not increased both in the control and zinc-deficient rats by stimulation with 100 mM KCl. These results suggest that GABAergic neurotransmitter system is critically impaired in the amygdala of young rats after 4-week zinc deprivation.     

A third-generation mouse model of Alzheimer's disease shows early and increased cored plaque pathology composed of wild-type human amyloid β peptide

We previously developed single App knock-in mouse models of Alzheimer''s disease (AD) harboring the Swedish and Beyreuther/Iberian mutations with or without the Arctic mutation (App^NL-G-F and App^NL-F mice, respectively). These models showed Aβ pathology, neuroinflammation, and cognitive impairment in an age-dependent manner. The former model exhibits extensive pathology as early as 6 months, but is unsuitable for investigating Aβ metabolism and clearance because the Arctic mutation renders Aβ resistant to proteolytic degradation and prone to aggregation. In particular, it is inapplicable to preclinical immunotherapy studies due to its discrete affinity for anti-Aβ antibodies. The latter model may take as long as 18 months for the pathology to become prominent, which leaves an unfulfilled need for an Alzheimer''s disease animal model that is both swift to show pathology and useful for antibody therapy. We thus utilized mutant Psen1 knock-in mice into which a pathogenic mutation (P117L) had been introduced to generate a new model that exhibits early deposition of wild-type human Aβ by crossbreeding the App^NL-F line with the Psen1^P117L/WT line. We show that the effects of the pathogenic mutations in the App and Psen1 genes are additive or synergistic. This new third-generation mouse model showed more cored plaque pathology and neuroinflammation than App^NL-G-F mice and will help accelerate the development of disease-modifying therapies to treat preclinical AD.     

Starches from different botanical sources I: Contribution of amylopectin fine structure to thermal properties and enzyme digestibility

Fifteen starches from different botanical sources were selected to study the influence of structural features on thermal properties and enzyme digestibility. Morphological appearance, X-ray diffraction pattern, apparent amylose content, unit-chain length distribution of amylopectin, thermal properties and enzyme digestibility of starch varied with botanical source. It was demonstrated that the distribution of unit-chains of amylopectin significantly correlated with functional properties of the starches. Gelatinization temperature of native and retrograded starches decreased and increased with a relative abundance of unit-chains with an approximate degree of polymerization (DP) of 8–12 and 16–26, respectively (P<0.01). Similar unit-chain lengths also affected the enzyme digestibility of starch granules (P<0.01).     

Identification of RNase HII from psychrotrophic bacterium, Shewanella sp. SIB1 as a high-activity type RNase H

The gene encoding RNase HII from the psychrotrophic bacterium, Shewanella sp. SIB1 was cloned, overexpressed in Escherichia coli, and the recombinant protein was purified and biochemically characterized. SIB1 RNase HII is a monomeric protein with 212 amino acid residues and shows an amino acid sequence identity of 64% to E. coli RNase HII. The enzymatic properties of SIB1 RNase HII, such as metal ion preference, pH optimum, and cleavage mode of substrate, were similar to those of E. coli RNase HII. SIB1 RNase HII was less stable than E. coli RNase HII, but the difference was marginal. The half-lives of SIB1 and E. coli RNases HII at 30 degrees C were approximately 30 and 45 min, respectively. The midpoint of the urea denaturation curve and optimum temperature of SIB1 RNase HII were lower than those of E. coli RNase HII by approximately 0.2 M and approximately 5 degrees C, respectively. However, SIB1 RNase HII was much more active than E. coli RNase HII at all temperatures studied. The specific activity of SIB1 RNase HII at 30 degrees C was 20 times that of E. coli RNase HII. Because SIB1 RNase HII was also much more active than SIB1 RNase HI, RNases HI and HII represent low- and high-activity type RNases H, respectively, in SIB1. In contrast, RNases HI and HII represent high- and low-activity type RNases H, respectively, in E. coli. We propose that bacterial cells usually contain low- and high-activity type RNases H, but these types are not correlated with RNase H families.     

Tissue expression map of a large number of expressed sequence tags and its application to in silico screening of stress response genes in common wheat

In order to assess global changes in gene expression patterns in stress-induced tissues, we conducted large-scale analysis of expressed sequence tags (ESTs) in common wheat. Twenty-one cDNA libraries derived from stress-induced tissues, such as callus, as well as liquid cultures and abiotic stress conditions (temperature treatment, desiccation, photoperiod, moisture and ABA) were constructed. Several thousand colonies were randomly selected from each of these 21 cDNA libraries and sequenced from both the 5′ and 3′ ends. By computing abundantly expressed ESTs, correlated expression patterns of genes across the tissues were monitored. Furthermore, the relationships between gene expression profiles among the stress-induced tissues were inferred from the gene expression patterns. Multi-dimensional analysis of EST data is analogous to microarray experiments. As an example, genes specifically induced and/or suppressed by cold acclimation and heat-shock treatments were selected in silico. Four hundred and ninety genes showing fivefold induction or 218 genes for suppression in comparison to the control expression level were selected. These selected genes were annotated with the BLAST search. Furthermore, gene ontology was conducted for these genes with the InterPro search. Because genes regulated in response to temperature treatment were successfully selected, this method can be applied to other stress-treated tissues. Then, the method was applied to screen genes in response to abiotic stresses such as drought and ABA treatments. In silico selection of screened genes from virtual display should provide a powerful tool for functional plant genomics.Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at .     

Overweight in urban schoolchildren assessed by body mass index and body fat mass in Dalian, China

In order to assess overweight in urban schoolchildren (298 boys and 298 girls) aged 9-16 years in Dalian, China, their body height, weight, skinfolds at triceps, biceps, subscapular and suprailiac, and body circumferences of mid-upper arm, waist and hip were measured. The results showed that the prevalence of overweight, based on the United States Centers for Disease Control 2000 reference values using body mass index (BMI), was 22.9% in boys and 10.4% in girls, which was higher than that of indicated in Chinese national surveys of recent decades. More boys were overweight than girls due to excessive increase in body fat, although the prevalence of overweight in girls prevalence increased from 13 years. Discussion here focuses on the effects of behavioral patterns on overweight in Dalian schoolchildren, paying attention to gender difference.     

Evolution of long-range myofibrillar crystallinity in insect flight muscle as examined by X-ray cryomicrodiffraction

Insect flight muscle is known for its crystal-quality regularity of contractile protein arrangement within a sarcomere. We have previously shown by X-ray microdiffraction that the crystal-quality regularity in bumble-bee flight muscle is not confined within a sarcomere, but extends over the entire length of a myofibril (>1000 sarcomeres connected in series). Because of this, the whole myofibril may be regarded as a millimetre-long, natural single protein crystal. Using bright X-ray beams from a synchrotron radiation source, we examined how this long-range crystallinity has evolved among winged insects. We analysed >4600 microdiffraction patterns of quick-frozen myofibrils from 50 insect species, covering all the major winged insect orders. The results show that the occurrence of such long-range crystallinity largely coincides with insect orders with asynchronous muscle operation. However, a few of the more skilled fliers among lower-order insects apparently have developed various degrees of structural regularity, suggesting that the demand for skillful flight has driven the lattice structure towards increased regularity.     

beta-Secretase inhibitors: modification at the P4 position and improvement of inhibitory activity in cultured cells

Recently, we reported potent and small-sized beta-secretase (BACE1) inhibitors KMI-570 and KMI-684 in which we replaced carboxylic acid groups at the P(1)(') position of KMI-420 and KMI-429, respectively, with tetrazole derivatives as carboxylic acid bioisosteres. These modifications improved significantly BACE1 inhibitory activity and chemical stability. In this study, the acidic tetrazole ring of the P(4) position of KMI-420 and KMI-570, respectively, was replaced with various hydrogen bond acceptor groups. We found BACE1 inhibitor KMI-574 that exhibited potent inhibitory activity in cultured cells as well as in vitro enzymatic assay.     

Field studies on the regulation of abscisic acid content and germinability during grain development of barley: molecular and chemical analysis of pre-harvest sprouting

To investigate whether the regulation of abscisic acid (ABA) content was related to germinability during grain development, two cDNAs for 9-cis-epoxycarotenoid dioxygenase (HvNCED1 and HvNCED2) and one cDNA for ABA 8'-hydroxylase (HvCYP707A1), which are enzymes thought to catalyse key regulatory steps in ABA biosynthesis and catabolism, respectively, were cloned from barley (Hordeum vulgare L.). Expression and ABA-quantification analysis in embryo revealed that HvNCED2 is responsible for a significant increase in ABA levels during the early to middle stages of grain development, and HvCYP707A1 is responsible for a rapid decrease in ABA level thereafter. The change in the embryonic ABA content of imbibing grains following dormancy release is likely to reflect changes in the expression patterns of HvNCEDs and HvCYP707A1. A major change between dormant and after-ripened grains occurred in HvCYP707A1; the increased expression of HvCYP707A1 in response to imbibition, followed by a rapid ABA decrease and a high germination percentage, was observed in the after-ripened grains, but not in the dormant grains. Under field conditions, HvNCED2 showed the same expression level and pattern during grain development in 2002, 2003, and 2004, indicating that HvNCED2 expression is regulated in a growth-dependent manner in the grains. By contrast, HvNCED1 and HvCYP707A1 showed a different expression pattern in each year, indicating that the expression of these genes is affected by environmental conditions during grain development. The varied expression levels of these genes during grain development and imbibition, which would have effects on the activity of ABA biosynthesis and catabolism, might be reflected, in part, in the germinability in field-grown barley.