Postnatal Development of Neurons,Interneurons and Glial Cells in the Substantia Nigra of Mice

We investigated postnatal alterations of neurons, interneurons and glial cells in the mouse substantia nigra using immunohistochemistry. Tyrosine hydroxylase (TH), neuronal nuclei (NeuN), parvalbumin (PV), neuronal nitric oxide synthase (nNOS), glial fibrillary acidic protein (GFAP), ionized calcium-binding adaptor molecule 1 (Iba 1), CNPase (2′,3′-cyclic nucleotide 3′-phosphodiesterase), brain-derived neurotrophic factor (BDNF) and glial cell-line-derived neurotrophic factor (GDNF) immunoreactivity were measured in 1-, 2-, 4- and 8-week-old mice. In the present study, the maturation of NeuN-immunopositive neurons preceded the production of TH in the substantia nigra during postnatal development in mice. Furthermore, the maturation of nNOS-immunopositive interneurons preceded the maturation of PV-immunopositive interneurons in the substantia nigra during postnatal development. Among astrocytes, microglia and oligodendrocytes, in contrast, the development process of oligodendrocytes is delayed in the substantia nigra. Our double-labeled immunohistochemical study suggests that the neurotrophic factors such as BDNF and GDNF secreted by GFAP-positive astrocytes may play some role in maturation of neurons, interneurons and glial cells of the substantia nigra during postnatal development in mice. Thus, our findings provide valuable information on the development processes of the substantia nigra.     

Tea catechins reduce inflammatory reactions via mitogen-activated protein kinase pathways in toll-like receptor 2 ligand-stimulated dental pulp cells

AimsIn this study, we evaluated whether catechins could inhibit the expression of pro-inflammatory mediators induced by dental caries-related bacteria, Streptococci, or pathogen-associated molecular patterns (PAMPs) stimulation in human dental pulp fibroblasts (HDPF). We further determined the mechanisms of the anti-inflammatory activity of catechins.Main methodsStreptococci or PAMP-stimulated HDPF were treated with catechin, and then the expression and production of pro-inflammatory mediators were determined by RT-PCR and ELISA. Furthermore, the signal transduction pathways activated with toll-like receptor (TLR)2 ligand were assessed by Immunoblot and ELISA using blocking assay with specific inhibitors.Key findingsIncreased expressions of pro-inflammatory mediators are found in inflamed dental pulp, especially in HDPF. We recently reported that dental pulpal innate immune responses may mainly result from the predominantly-expressed TLR2 signaling. Catechins, polyphenolic compounds in green tea, exert protective and healing effects through multiple mechanisms, including antioxidative and anti-inflammatory effects. However, there are no reports concerning the effects of catechins on dental pulp. In this study, we demonstrated that the up-regulated expressions of IL-8 or PGE₂ in Streptococci or PAMP-stimulated HDPF were inhibited by catechins, (?)-epicatechin gallate (ECG) and (?)-epigallocatechin gallate (EGCG). In TLR2 ligand-stimulated HDPF, specific inhibitors of extracellular signal regulated kinase (ERK)1/2, p38, c-jun NH₂-terminal kinase (SAP/JNK), NF-κB or catechins markedly reduced the level of pro-inflammatory mediators and the phosphorylation of these signal transduction molecules was suppressed by catechins.SignificanceThese findings suggest that catechins might be useful therapeutically as an anti-inflammatory modulator of dental pulpal inflammation.     

Ancestral MADS box genes in Sugi, Cryptomeria japonica D. Don (Taxodiaceae), homologous to the B function genes in angiosperms.

In flowering plants, flower organ identity is controlled by the ABC genes, including several MADS box genes. We present two MADS box genes of a conifer, Cryptomeria japonica D. Don. The genes, CjMADS1 and CjMADS2, were related to the angiosperm B function genes which determine the identities of petals and stamens. A phylogenetic analysis showed that these genes form a new clade outside the angiosperm B group, that is, PISTILLATA (PI) and APETALA3 (AP3) lineages. CjMADS1 had a PI-group specific motif and CjMADS2 had AP3-group specific motifs at the C terminal end, respectively. CjMADS1 was expressed in male strobili (or cones) throughout its development, while CjMADS2 was transiently expressed during male strobilus development. The specific expression in the male reproductive organ indicated that the B function is maintained in gymnosperms. Our cladistic analysis suggests that the gene duplication event which generated B function gene lineages predates the divergence of angiosperms and gymnosperms and that the gene duplication which produced the two genes of C. japonica occurred in an ancestral conifer species.     

Phylogenetic evidence for a flower size and number trade-off

The size and number of flowers displayed together on an inflorescence (floral display) influences pollinator attraction and pollen transfer and receipt, and is integral to plant reproductive success and fitness. Life history theory predicts that the evolution of floral display is constrained by trade-offs between the size and number of flowers and inflorescences. Indeed, a trade-off between flower size and flower number is a key assumption of models of inflorescence architecture and the evolution of floral display. Surprisingly, however, empirical evidence for the trade-off is limited. In particular, there is a lack of phylogenetic evidence for a trade-off between flower size and number. Analyses of phylogenetic independent contrasts (PICs) of 251 angiosperm species spanning 63 families yielded a significant negative correlation between flower size and flower number. At smaller phylogenetic scales, analyses of individual genera did not always find evidence of a trade-off, a result consistent with previous studies that have examined the trade-off for a single species or genus. Ours is the first study to support an angiosperm-wide trade-off between flower size and number and supports the theory that life history constraints have influenced the evolution of floral display.     

Gene silencing by RNA interference in the koji mold Aspergillus oryzae

We found the orthologous genes required for RNA interference (RNAi) in the Aspergillus oryzae genome database, and constructed a set of tools for gene silencing using RNAi in A. oryzae. This system utilizes compatible restriction enzyme sites so that only a single target gene fragment is required to create the hairpin RNA cassette. For ease of handling, we also separated the construction of the hairpin RNA cassette for the target gene from its subsequent introduction into the expression vector. Using the brlA gene as a target for RNAi, we detected decreased mRNA levels and a delayed conidiation phenotype in the transformants. Furthermore, even though A. oryzae possesses three copies of the alpha-amylase gene, a single copy of an alpha-amylase RNAi construct was sufficient to downregulate the mRNA levels and decrease the enzymatic activity to 10% of control levels. Gene silencing by RNAi should provide a powerful genetic tool for post-genomic studies of the industrially important fungus A. oryzae.     

Reassignment of a rare sense codon to a non-canonical amino acid in Escherichia coli

The immutability of the genetic code has been challenged with the successful reassignment of the UAG stop codon to non-natural amino acids in Escherichia coli. In the present study, we demonstrated the in vivo reassignment of the AGG sense codon from arginine to l-homoarginine. As the first step, we engineered a novel variant of the archaeal pyrrolysyl-tRNA synthetase (PylRS) able to recognize l-homoarginine and l-N⁶-(1-iminoethyl)lysine (l-NIL). When this PylRS variant or HarRS was expressed in E. coli, together with the AGG-reading tRNA^Pyl_CCU molecule, these arginine analogs were efficiently incorporated into proteins in response to AGG. Next, some or all of the AGG codons in the essential genes were eliminated by their synonymous replacements with other arginine codons, whereas the majority of the AGG codons remained in the genome. The bacterial host''s ability to translate AGG into arginine was then restricted in a temperature-dependent manner. The temperature sensitivity caused by this restriction was rescued by the translation of AGG to l-homoarginine or l-NIL. The assignment of AGG to l-homoarginine in the cells was confirmed by mass spectrometric analyses. The results showed the feasibility of breaking the degeneracy of sense codons to enhance the amino-acid diversity in the genetic code.     

The tRNA Splicing Endonuclease Complex Cleaves the Mitochondria-localized CBP1 mRNA

The tRNA splicing endonuclease (Sen) complex is located on the mitochondrial outer membrane and splices precursor tRNAs in Saccharomyces cerevisiae. Here, we demonstrate that the Sen complex cleaves the mitochondria-localized mRNA encoding Cbp1 (cytochrome b mRNA processing 1). Endonucleolytic cleavage of this mRNA required two cis-elements: the mitochondrial targeting signal and the stem-loop 652–726-nt region. Mitochondrial localization of the Sen complex was required for cleavage of the CBP1 mRNA, and the Sen complex cleaved this mRNA directly in vitro. We propose that the Sen complex cleaves the CBP1 mRNA, which is co-translationally localized to mitochondria via its mitochondrial targeting signal.     

Effect of birth season on circadian typology appearing in Japanese young children aged 2 to 12 years disappears in older students aged 18 to 25 years

Several studies suggest that season of birth differentially affects the physiological characteristics of humans. Those living at relatively high latitude, such as Canada, Spain, and Italy (44°N-45°N), and born in the fall tended to be "morning-type" persons in comparison to those born in other seasons. There are relatively little data on the affect of season of birth on people residing at low latitude. Here the authors show that at low latitude, Kochi, Japan (33°N), the effect of season of birth on the morningness chronotype is confined to young children aged 1-12 yrs, disappearing in elderly persons. Only female participants aged 2-12 yrs born in the fall, especially in November, were significantly morning-typed (p < .001) in comparison to those born in the other seasons, whereas there were no such significant season-of-birth differences in morningness-eveningness preference among male participants. Moreover, both female and male participants aged 13-25 yrs showed no significant seasonal differences in morningness-eveningness preference. The small effects detected in this study might be due to smaller seasonal change in day length at the relatively lower latitude of Kochi.