Competition and cooperation among receptor tyrosine phosphatases control motoneuron growth cone guidance in Drosophila

The neural receptor tyrosine phosphatases DPTP69D, DPTP99A and DLAR are involved in motor axon guidance in the Drosophila embryo. Here we analyze the requirements for these three phosphatases in growth cone guidance decisions along the ISN and SNb motor pathways. Any one of the three suffices for the progression of ISN pioneer growth cones beyond their first intermediate target in the dorsal muscle field. DLAR or DPTP69D can facilitate outgrowth beyond a second intermediate target, and DLAR is uniquely required for formation of a normal terminal arbor. A different pattern of partial redundancy among the three phosphatases is observed for the SNb pathway. Any one of the three suffices to allow SNb axons to leave the common ISN pathway at the exit junction. When DLAR is not expressed, however, SNb axons sometimes bypass their ventrolateral muscle targets after leaving the common pathway, instead growing out as a separate bundle adjacent to the ISN. This abnormal guidance decision can be completely suppressed by also removing DPTP99A, suggesting that DLAR turns off or counteracts a DPTP99A signal that favors the bypass axon trajectory. Our results show that the relationships among the tyrosine phosphatases are complex and dependent on cellular context. At growth cone choice points along one nerve, two phosphatases cooperate, while along another nerve these same phosphatases can act in opposition to one another

House Musk Shrews (Suncus murinus) Do Not Copulate in the Light Period when First Paired in the Dark

The copulatory behavior pattern of house musk shrews paired for 24 h starting at either 09:00 (light) or 20:00 (dark) was investigated. Ejaculatory behaviors were observed in both light and dark periods, when mating was started at 09:00. However, the males ejaculated only in the dark period when they were paired at 20:00

Measure of synonymous codon usage diversity among genes in bacteria

<p>Abstract</p> <p>Background</p> <p>In many bacteria, intragenomic diversity in synonymous codon usage among genes has been reported. However, no quantitative attempt has been made to compare the diversity levels among different genomes. Here, we introduce a mean dissimilarity-based index (<it>D</it>mean) for quantifying the level of diversity in synonymous codon usage among all genes within a genome.</p> <p>Results</p> <p>The application of <it>D</it>mean to 268 bacterial genomes shows that in bacteria with extremely biased genomic G+C compositions there is little diversity in synonymous codon usage among genes. Furthermore, our findings contradict previous reports. For example, a low level of diversity in codon usage among genes has been reported for <it>Helicobacter pylori</it>, but based on <it>D</it>mean, the diversity level of this species is higher than those of more than half of bacteria tested here. The discrepancies between our findings and previous reports are probably due to differences in the methods used for measuring codon usage diversity.</p> <p>Conclusion</p> <p>We recommend that <it>D</it>mean be used to measure the diversity level of codon usage among genes. This measure can be applied to other compositional features such as amino acid usage and dinucleotide relative abundance as a genomic signature.</p

Variation in the Correlation of G + C Composition with Synonymous Codon Usage Bias among Bacteria

G + C composition at the third codon position (GC3) is widely reported to be correlated with synonymous codon usage bias. However, no quantitative attempt has been made to compare the extent of this correlation among different genomes. Here, we applied Shannon entropy from information theory to measure the degree of GC3 bias and that of synonymous codon usage bias of each gene. The strength of the correlation of GC3 with synonymous codon usage bias, quantified by a correlation coefficient, varied widely among bacterial genomes, ranging from −0.07 to 0.95. Previous analyses suggesting that the relationship between GC3 and synonymous codon usage bias is independent of species are thus inconsistent with the more detailed analyses obtained here for individual species

Yeast osmosensor Sln1 and plant cytokinin receptor Cre1 respond to changes in turgor pressure

Very little is known about how cellular osmosensors monitor changes in osmolarity of the environment. Here, we report that in yeast, Sln1 osmosensor histidine kinase monitors changes in turgor pressures. Reductions in turgor caused by either hyperosmotic stress, nystatin, or removal of cell wall activate MAPK Hog1 specifically through the SLN1 branch, but not through the SHO1 branch of the high osmolarity glycerol pathway. The integrity of the periplasmic region of Sln1 was essential for its sensor function. We found that activity of the plant histidine kinase cytokinin response 1 (Cre1) is also regulated by changes in turgor pressure, in a manner identical to that of Sln1, in the presence of cytokinin. We propose that Sln1 and Cre1 are turgor sensors, and that similar turgor-sensing mechanisms might regulate hyperosmotic stress responses both in yeast and plants

The receptor tyrosine phosphatase Dlar and integrins organize actin filaments in the Drosophila follicular epithelium

Background: Regulation of actin structures is instrumental in maintaining proper cytoarchitecture in many tissues. In the follicular epithelium of Drosophila ovaries, a system of actin filaments is coordinated across the basal surface of cells encircling the oocyte. These filaments have been postulated to regulate oocyte elongation; however, the molecular components that control this cytoskeletal array are not yet understood. Results: We find that the receptor tyrosine phosphatase (RPTP) Dlar and integrins are involved in organizing basal actin filaments in follicle cells. Mutations in Dlar and the common β-integrin subunit mys cause a failure in oocyte elongation, which is correlated with a loss of proper actin filament organization. Immunolocalization shows that early in oogenesis Dlar is polarized to membranes where filaments terminate but becomes generally distributed late in development, at which time β-integrin and Enabled specifically associate with actin filament terminals. Rescue experiments point to the early period of polar Dlar localization as critical for its function. Furthermore, clonal analysis shows that loss of Dlar or mys influences actin filament polarity in wild-type cells that surround mutant tissues, suggesting that communication between neighboring cells regulates cytoskeletal organization. Finally, we find that two integrin α subunits encoded by mew and if are required for proper oocyte elongation, implying that multiple components of the ECM are instructive in coordinating actin fiber polarity. Conclusions: Dlar cooperates with integrins to coordinate actin filaments at the basal surface of the follicular epithelium. To our knowledge, this is the first direct demonstration of an RPTP\u27s influence on the actin cytoskeleton

胃がん検診用高濃度硫酸バリウムの物理特性

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The University of Tokyo forests and forest science education in Japan

In-forest teaching is a vital element of forest science education at university level, and university forests play a critical role in this. In Japan, the University of Tokyo (UTokyo) owns the oldest university forest, which was established in 1894. This paper outlines how the University of Tokyo Forests (UTF) provide in-forest education for forest science. The UTF consist of seven branch stations with a total area of over 32,000 ha. Third- and fourth-year undergraduate students majoring in forest science attend field courses in these forests. Same undergraduate and graduate students are affiliated with the UTF, where they conduct field studies for their graduate theses. Since 2005, the UTF have expanded their educational activities by offering university-wide hands-on experience seminars with field experience for first- and second-year undergraduate students, although these courses are open to all students studying at UTokyo