A single-cell RNA-seq analysis of early larval cell-types of the starfish, Patiria pectinifera: Insights into evolution of the chordate body plan.

Ambulacrarians (echinoderms and hemichordates) are a sister group to chordates; thus, their larval cell-types may provide clues about evolution of chordate body plans. Although most genic information accumulated to date pertains to sea urchin embryogenesis, starfish embryogenesis represents a more ancestral mode than that of sea urchins. We performed single-cell RNA-seq analysis of cell-types from gastrulae and bipinnarial larvae of the starfish, Patiria pectinifera, and categorized them into 22 clusters, each of which is composed of cells with specific, shared profiles of development-relevant gene expression. Oral and aboral ectoderm, apical plate, hindgut or archenteron, midgut or intestine, pharynx, endomesoderm, stomodeum, and mesenchyme of the gastrulae, and neurons, ciliary bands, enterocoel and muscle of larvae were characterized by expression profiles of at least two relevant transcription factor genes and signaling molecular genes. Expression of Hox2, Hox7, Hox9/10, and Hox11/13b was detected in cells of clusters that form the larval enterocoel. By comparing homologous gene expression profiles in chordate embryos, we discuss and propose how the chordate body plan evolved from a deuterostome ancestor, from which the echinoderm body plan also evolved.

A single-cell RNA-seq analysis of Brachyury-expressing cell clusters suggests a morphogenesis-associated signal center of oral ectoderm in sea urchin embryos.

Brachyury is a T-box family transcription factor and plays pivotal roles in morphogenesis. In sea urchin embryos, Brachyury is expressed in the invaginating endoderm, and in the oral ectoderm of the invaginating mouth opening. The oral ectoderm is hypothesized to serve as a signaling center for oral (ventral)-aboral (dorsal) axis formation and to function as a ventral organizer. Our previous results of a single-cell RNA-seq (scRNA-seq) atlas of early Strongylocentrotus purpuratus embryos categorized the constituent cells into 22 clusters, in which the endoderm consists of three clusters and the oral ectoderm four clusters (Foster et al., 2020). Here we examined which clusters of cells expressed Brachyury in relation to the morphogenesis and the identity of the ventral organizer. Our results showed that cells of all three endoderm clusters expressed Brachyury in blastulae. Based on expression profiles of genes involved in the gene regulatory networks (GRNs) of sea urchin embryos, the three clusters are distinguishable, two likely derived from the Veg2 tier and one from the Veg1 tier. On the other hand, of the four oral-ectoderm clusters, cells of two clusters expressed Brachyury at the gastrula stage and genes that are responsible for the ventral organizer at the late blastula stage, but the other two clusters did not. At a single-cell level, most cells of the two oral-ectoderm clusters expressed organizer-related genes, nearly a half of which coincidently expressed Brachyury. This suggests that the ventral organizer contains Brachyury-positive cells which invaginate to form the stomodeum. This scRNA-seq study therefore highlights significant roles of Brachyury-expressing cells in body-plan formation of early sea urchin embryos, though cellular and molecular mechanisms for how Brachyury functions in these processes remain to be elucidated in future studies.

A Preliminary Single-Cell RNA-Seq Analysis of Embryonic Cells That Express Brachyury in the Amphioxus, Branchiostoma japonicum.

Among chordate taxa, the cephalochordates diverged earlier than urochordates and vertebrates; thus, they retain unique, primitive developmental features. In particular, the amphioxus notochord has muscle-like properties, a feature not seen in urochordates or vertebrates. Amphioxus contains two Brachyury genes, Bra1 and Bra2. Bra2 is reportedly expressed in the blastopore, notochord, somites, and tail bud, in contrast to a low level of Bra1 expression only in notochord. To distinguish the expression profiles of the two Brachyury genes at the single-cell level, we carried out single-cell RNA-seq (scRNA-seq) analysis using the amphioxus, Branchiostoma japonicum. This scRNA-seq analysis classified B. japonicum embryonic cells into 15 clusters at developmental stages from midgastrula to early swimming larva. Brachyury was expressed in cells of clusters 4, 5, 8, and 9. We first confirmed that cluster 8 comprises cells that form somites since this cluster specifically expresses four myogenic factor genes. Cluster 9 contains a larger number of cells with high levels of Bra2 expression and a smaller number of cells with Bra1 expression. Simultaneous expression in cluster 9 of tool-kit genes, including FoxA, Goosecoid, and hedgehog, showed that this cluster comprises cells that form the notochord. Expression of Bra2, but not Bra1, in cells of clusters 4 and 5 at the gastrula stage together with expression of Wnt1 and Caudal indicates that clusters 4 and 5 comprise cells of the blastopore, which contiguously form the tail bud. In addition, Hox1, Hox3, and Hox4 were highly expressed in Bra2-expressing clusters 4, 5, 8, and 9 in a temporally coordinated manner, suggesting roles of anterior Hox genes in specification of mesodermal organs, including somites, notochord, and tail bud. This scRNA-seq analysis therefore highlights differences between the two Brachyury genes in relation to embryonic regions in which they are expressed and their levels of expression. Bra2 is the ancestral Brachyury in amphioxus, since expression in the blastopore is shared with other deuterostomes. On the other hand, Bra1 is a duplicate copy and likely evolved a supplementary function in notochord and somite formation in the Branchiostoma lineage.

Enhancer activities of amphioxus Brachyury genes in embryos of the ascidian, Ciona intestinalis.

The notochord and somites are distinctive chordate structures. The T-box transcription factor gene, Brachyury, is expressed in notochord and plays a pivotal role in its formation. In the cephalochordate, Branchiostoma floridae, Brachyury is duplicated into BfBra1 and BfBra2, which are expressed in the somite-formation region as well. In a series of experiments to elucidate the regulatory machinery of chordate Brachyury expression, we carried out a lacZ reporter assay of BfBra in embryos of the urochordate, Ciona intestinalis. Vista analyses suggest the presence of conserved non-coding sequences, not only in the 5'-upstream, but also in the 3'-downstream and in introns of BfBra. We found that: (1) 5'-upstream sequences of both BfBra1 and BfBra2 promote lacZ expression in muscle cells, (2) 3'-downstream sequences have enhancer activity that promotes lacZ expression in notochord cells, and (3) introns of BfBra2 and BfBra1 exhibit lacZ expression preferentially in muscle and notochord cells. These results suggest shared cephalochordate Brachyury enhancer machinery that also works in urochordates. We discuss the results in relation to evolutionary modification of Brachyury expression in formation of chordate-specific organs characteristic of each lineage.

Negative Affect during a Collective (but Not an Individual) Task Is Associated with Holistic Attention in East Asian Cultural Context.

Previous studies have suggested that individuals from East Asian cultures are more likely to show holistic attention-a pattern of attention that incorporates contextual information into focal stimuli-than individuals from North American cultures. Holistic attention is also prevalent in communities that require close cooperation. However, it is not yet known how cooperation is related to holistic attention. We theorized that holistic attention increases when people experience negative affect (e.g., worry, sadness, and frustration) during collective tasks (but not during individual tasks) because negative affect in social contexts signals the existence of potential threats to social harmony, thus indicating a need to restore social harmony. To examine this hypothesis, an experiment was conducted in which participants performed a musical duet either with another participant (a collective task requiring cooperation), or individually with a computer (an individual task). After the musical task, the Framed Line Task (FLT) was administered to examine their holistic attention. Participants also reported their emotional states both before and after the music task. Results suggested that negative affect in the collective task-but not the individual task-was positively correlated with a holistic pattern of attention. The function of negative affect in social contexts as motivation to restore relationships and how this enhances holistic attention is discussed. The moderating effect of social context on the link between negative affect and cognition is also discussed.

Are common names becoming less common? The rise in uniqueness and individualism in Japan.

We examined whether Japanese culture has become more individualistic by investigating how the practice of naming babies has changed over time. Cultural psychology has revealed substantial cultural variation in human psychology and behavior, emphasizing the mutual construction of socio-cultural environment and mind. However, much of the past research did not account for the fact that culture is changing. Indeed, archival data on behavior (e.g., divorce rates) suggest a rise in individualism in the U.S. and Japan. In addition to archival data, cultural products (which express an individual's psyche and behavior outside the head; e.g., advertising) can also reveal cultural change. However, little research has investigated the changes in individualism in East Asia using cultural products. To reveal the dynamic aspects of culture, it is important to present temporal data across cultures. In this study, we examined baby names as a cultural product. If Japanese culture has become more individualistic, parents would be expected to give their children unique names. Using two databases, we calculated the rate of popular baby names between 2004 and 2013. Both databases released the rankings of popular names and their rates within the sample. As Japanese names are generally comprised of both written Chinese characters and their pronunciations, we analyzed these two separately. We found that the rate of popular Chinese characters increased, whereas the rate of popular pronunciations decreased. However, only the rate of popular pronunciations was associated with a previously validated collectivism index. Moreover, we examined the pronunciation variation of common combinations of Chinese characters and the written form variation of common pronunciations. We found that the variation of written forms decreased, whereas the variation of pronunciations increased over time. Taken together, these results showed that parents are giving their children unique names by pairing common Chinese characters with uncommon pronunciations, which indicates an increase in individualism in Japan.

Synthesis and cosmetic whitening effect of glycosides derived from several phenylpropanoids.

Plant-derived phenylpropanoid compounds (4-ethyl-2-methoxyphenol, 2,6-dimethoxyphenol, 2,3-dimethoxyphenol, 3,4-dimethoxyphenol, 3,5-dimethoxyphenol, 3,4-dihydroxycinnamic acid, 4-hydroxy-3-methoxycinnamic acid, and 3-hydroxy-4-methoxycinnamic acid) were glycosidated to form glycoside compounds. We evaluated the effects of these compounds on the inhibition of tyrosinase and melanin synthesis and their cytotoxicity from the viewpoint of their use as whitening agents in cosmetics. Some compounds had more potent tyrosinase-inhibiting activity than commercial arbutin, which was used as a control, and showed no cytotoxicity at low concentration ranges.

DPPH radical-scavenging effect of several phenylpropanoid compounds and their glycoside derivatives.

Eugenol, isoeugenol, caffeic acid, ferulic acid, isoferulic acid, estragole, trans-anethole, and paeonol are components of a Chinese herbal medicine used as a painkiller and stomachic. We investigated the potential role of these compounds as antioxidants. We studied the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging effect of these molecules, together with some glycoside derivatives, to ascertain their potential in reducing the levels of activated oxygen species in vivo. The DPPH radical-scavenging effects of eugenol, isoeugenol, and the glycoside derivatives of caffeic acid, ferulic acid, and isoferulic acid (SC(50)=8-28 microM) were similar to those of alpha-tocopherol, which was used as a positive control.