Histidine-containing cyclic dipeptides as catalysts in the hydrolysis of carbonic acid p-nitrophenyl esters

A histidine-containing cyclic dipeptide, cyclo(D -Leu-L -His), was almost 20 times as efficient a catalyst as imidazole in the hydrolysis of p-nitrophenyl laurate. The effect of dioxane on the hydrolysis showed that hydrophobic interaction between the cyclic dipeptide and the ester is very important. This reaction obeyed the Michaelis-Menten kinetics, and the Michaelis constant K_m was as low as 9.98 × 10^?5M. Since the linear dipeptide having D -Leu-L -His sequence was nearly inactive in the hydrolysis, the functional groups of cyclo(D -Leu-L -His) in a specific arrangement held by the rigid backbone must have cooperated in the fast hydrolysis. Very weak catalysis by the diasteremeric cyclic dipeptide, cyclo(L -Leu-L -His), in the hydrolysis supported the above view.     

Diversity of the cadherin family: evidence for eight new cadherins in nervous tissue.

To examine the diversity of the cadherin family, we isolated cDNAs from brain and retina cDNA preparations with the aid of polymerase chain reaction. The products obtained included cDNAs for two of three known cadherins as well as eight distinct cDNAs, of which deduced amino acid sequences show significant similarity with the known cadherin sequences. Larger cDNA clones were isolated from human cDNA libraries for six of the eight new molecules. The deduced amino acid sequences show that the overall structure of these molecules is very similar to that of the known cadherins, indicating that these molecules are new members of the cadherin family. We have tentatively designated these cadherins as cadherin-4 through -11. The new molecules, with the exception of cadherin-4, exhibit features that distinguish them as a group from previously cloned cadherins; they may belong to a new subfamily of cadherins. Northern blot analysis showed that most of these cadherins are expressed mainly in brain, although some are expressed in other tissues as well. These findings show that the cadherin family of adhesion molecules is much larger than previously thought, and suggest that the new cadherins may play an important role in cell-cell interactions within the central nervous system.     

Four-dimensional imaging with virtual reality to quantitatively explore jigsaw puzzle-like morphogenesis of Arabidopsis cotyledon pavement cells

In most dicotyledonous plants, leaf pavement cells exhibit complex jigsaw puzzle-like cell morphogenesis during leaf expansion. Although detailed molecular biological information and mathematical modeling of this jigsaw puzzle-like cell morphogenesis are now available, a full understanding of this process remains elusive. Recent reports have highlighted the importance of three-dimensional (3D) structures (i.e., anticlinal and periclinal cell wall) in understanding the mechanical models that describe this morphogenetic process. We believe that it is important to acquire 3D shapes of pavement cells over time, i.e., acquire and analyze four-dimensional (4D) information when studying the relationship between mechanical modeling and simulations and the actual cell shape. In this report, we have developed a framework to capture and analyze 4D morphological information of Arabidopsis thaliana cotyledon pavement cells by using both direct water immersion observations and computational image analyses, including segmentation, surface modeling, virtual reality and morphometry. The 4D cell models allowed us to perform time-lapse 3D morphometrical analysis, providing detailed quantitative information about changes in cell growth rate and shape, with cellular complexity observed to increase during cell growth. The framework should enable analysis of various phenotypes (e.g., mutants) in greater detail, especially in the 3D deformation of the cotyledon surface, and evaluation of theoretical models that describe pavement cell morphogenesis using computational simulations. Additionally, our accurate and high-throughput acquisition of growing cell structures should be suitable for use in generating in silico model cell structures.     

Novel mutations of CDKN1C in Japanese patients with Beckwith-Wiedemann syndrome

Beckwith-Wiedemann syndrome (BWS) is an imprinting-related human disease that is characterized by macrosomia, macroglossia, abdominal wall defects, and variable minor features. BWS is caused by several genetic/epigenetic alterations, such as loss of methylation at KvDMR1, gain of methylation at H19-DMR, paternal uniparental disomy of chromosome 11, CDKN1C mutations, and structural abnormalities of chromosome 11. CDKN1C is an imprinted gene with maternal preferential expression, encoding for a cyclin-dependent kinase (CDK) inhibitor. Mutations in CDKN1C are found in 40 % of familial BWS cases with dominant maternal transmission and in ~5 % of sporadic cases. In this study, we searched for CDKN1C mutations in 37 BWS cases that had no evidence for other alterations. We found five mutations—four novel and one known—from a total of six patients. Four were maternally inherited and one was a de novo mutation. Two frame-shift mutations and one nonsense mutation abolished the QT domain, containing a PCNA-binding domain and a nuclear localization signal. Two missense mutations occurred in the CDK inhibitory domain, diminishing its inhibitory function. The above-mentioned mutations were predicted by in silico analysis to lead to loss of function; therefore, we strongly suspect that such anomalies are causative in the etiology of BWS.     

Evaluation of a high-affinity QCM immunosensor using antibody fragmentation and 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer

This study evaluated construction of a highly affinitive quartz crystal microbalance (QCM) immunosensor using anti-C-reactive protein (CRP) antibody and its fragments for CRP detection. Three types of antibody were immobilized on the surface of a QCM via covalent-bounding. Then affinity was evaluated through antigen-antibody binding between CRP and its antibody. Affinity between antigen-antibody was shown to be highest when anti-CRP F(ab')2-IgG antibody (70 microg/mL) was immobilized on the QCM. In case of anti-CRP F(ab')2-IgG antibody, affinity which was attributable to antigen-antibody binding was almost twice that of anti-CRP IgG antibody, which is used conventionally for QCM immunosensors. In addition, when it was treated with 2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate, so-called MPC polymer, highly affinitive and selective immunosensing for CRP was achieved without non-specific binding from plasma proteins in human serum. When anti-CRP F(ab')2-IgG antibody was immobilized on the QCM, the detection limit and the linearity of CRP calibration curve were achieved at concentrations from 0.001 to 100 microg/dL even during investigation in serum samples. Experimental results verified the successful construction of a highly affinitive and selective QCM-immunosensor which was modified with anti-CRP F(ab')2-IgG antibody and MPC polymer.     

Brain-derived neurotrophic factor shows a protective effect and improves recovery of the ERG b-wave response in light-damage

We investigated the neuroprotective effects of brain-derived neurotrophic factor (BDNF) and its influence on the functional recovery of the retina following light-induced retinal damage by electroretinogram (ERG). Rats were exposed to constant fluorescent light for 2, 5, 7, or 14 days, then returned to a cyclic light environment for 14 days. The result indicated that BDNF had few effects on the a-wave amplitude, but there was a statistically significant difference in the b-wave amplitudes between BDNF-treated and control eyes from day 0-14 of the recovery period following 2 days of light exposure (p < 0.05). Our findings suggest that BDNF not only protects the retinal neuronal function but also enhances the recovery from retinal light damage.     

A gene cluster responsible for alkylaldoxime metabolism coexisting with nitrile hydratase and amidase in Rhodococcus globerulus A-4

An enzyme "alkylaldoxime dehydratase (OxdRG)" was purified and characterized from Rhodococcus globerulus A-4, in which nitrile hydratase (NHase) and amidase coexisted with the enzyme. The enzyme contains heme b as a prosthetic group, requires reducing reagents for the reaction, and is most active at a neutral pH and at around 30 degrees C, similar to the phenylacetaldoxime dehydratase from Bacillus sp. OxB-1 (OxdB). However, some differences were seen in subunit structure, substrate specificity, and effects of activators and inhibitors. The corresponding gene, oxd, encoding a 1059-base pair ORF consisting of 353 codons, was cloned, sequenced, and overexpressed in Escherichia coli. The predicted polypeptide showed 30.3% identity to OxdB. The gene is mapped just upstream of the gene cluster encoding the enzymes involved in the metabolism of aliphatic nitriles, i.e., NHase and amidase, and their regulatory and activator proteins. We report here the existence of an aldoxime dehydratase genetically linked with NHase and amidase, and responsible for the metabolism of alkylaldoxime in R. globerulus.