Moulting behaviour in the trilobite Oryctocephalus indicus (Reed, 1910) from the Cambrian Miaolingian Series (Wuliuan Stage) of Jianhe, South China.

The accurate interpretation of trilobite moulting behaviour relies on a comprehensive understanding of their moult configurations, yet the focus has commonly been limited to a brief description of the exuviae, and how differences in moulting behaviour further impact the preservation of exuviae is often ignored. This study investigates the configuration, style, and process of moulting in Oryctocephalus indicus through analysis of 88 exuviae collected from the Kaili Formation (Cambrian, Wuliuan) in Guizhou Province, South China. The moult configurations of O. indicus are typically characterised by the lower cephalic unit (LCU), which comprises the librigenae and rostral-hypostomal plate connected as a whole, detached from the cephalon and positioned anterior to the thoracopygon, while the cranidium is mostly absent. From detailed observation and description of the available material, we believe that O. indicus completes its moult through an exuvial gape formed by disarticulation of the facial sutures, rostral sutures and/or sutures of the cephalothoracic joints. Although many exuviae exhibited an opening at the cephalothoracic joint-disjunction of which is usually accompanied by disarticulation of both the facial and rostral sutures-the Salter's configuration produced by the 'Salterian' mode of moulting was not observed. Additionally, the structural characteristics of Henningsmoen's configuration, Harrington's configuration, and Somersault's configuration are discussed based on the exuviae of O. indicus, and Henningsmoen's configuration has been categorised into three types according to the different states of fossil preservation. In this article, apart from promoting further research on moulting behaviour in O. indicus, we also provide a supplement for moult configuration based on the exuviae, which offers new materials for studying moulting behaviour in oryctocephalid trilobites.

The First Report of the Acrotretoid Brachiopod Hadrotreta from the Tsinghsutung Formation Cambrian (Series 2, Stage 4), Guizhou, South China.

Hadrotreta is a worldwide acrotretoid brachiopod reported from the Cambrian Series 2 to Miaolingian. Here, a number of well-preserved fossils of Hadrotreta, identified as Hadrotreta cf. H. timchristiorum, were found in the Protoryctocephalus arcticus Zone of the Tsinghsutung Formation of Cambrian Series 2, Stage 4 in Jianhe, Guizhou, south China. This is the first report of Hadrotreta in China, which enriches its global palaeogeographical distribution. Hadrotreta is very similar to acrotretoids such as Kostjubella, Vandalotreta, Linnarssonia, and Eohadrotreta. It differs from them with its well-developed ventral boss-like apical process, apical pits, and dorsal median sulcus. In view of the palaeogeography of Hadrotreta, this genus was mainly distributed in low-latitude regions. Hadrotreta was only found in south China and Laurentia during the Cambrian Age 4, then expanded its distribution to other regions such as Siberia, Baltica, the Kazakh Terranes, the Far East, and Gondwana Pange during the Miaolingian Epoch. Hadrotreta seems to have shifted from deeper water to shallow-water environments during the period from the Cambrian Series 2 to the Miaolingian.

Life cycle evolution in the trilobites Balangia and Duyunaspis from the Cambrian Series 2 (Stage 4) of South China.

The evolution process can be reconstructed by tracking the changes in the dynamic characters of life cycles. A number of related trilobites from the Cambrian of South China provide additional information for the study of trilobite evolutionary patterns, which has been hampered by previous incomplete fossil record though. Here, Balangia and Duyunaspis represent related Cambrian oryctocephalid trilobites from South China, are comprehensively discussed over the ontogeny, and the results show that, from B. balangensis via D. duyunensis to D. jianheensis, their exoskeletal morphology shows a directional evolution. Based on the direction of evolutionary changes in the development of Balangia and Duyunaspis, we speculate that Duyunaspis likely evolved from Balangia instead of Balangia evolved from Duyunaspis, as was previously assumed. This inference is also supported by the phylogenetic tree. This research provides not only a better understanding of the mechanisms of evolution in trilobites, but also new insights for the relationship between developmental evolutionary changes and phylogeny in trilobites.

Synchronized moulting behaviour in trilobites from the Cambrian Series 2 of South China.

The study of moulting behaviour in the fossil record is relatively well known in arthropods and this is especially true for trilobites. Nevertheless, while studies focusing on the style of moulting in social and semi-social groups of modern animals (e.g. arthropods) are common, very few works investigate moulting adaptations in deep time. Here we report a trilobite assemblage from the Cambrian Series 2 "Tsinghsutung" Formation of South China. Around 850 specimens were used for this study from three different levels across one section near Balang (SE Guizhou Province, South China). These levels preserve numerous trilobite clusters in some cases containing around 400 individual specimens. Up to four species have been found in these clusters, but two species are more common. Trilobite clusters bear a high percentage of disarticulated specimens that we interpret as moults. Additionally, measurements of bioclast orientation and the dorsoventral attitude suggests very quiet water conditions followed by rapid burial events, prior to scavenger disturbance. Together, this indicates that the fossil assemblages were a result of a biological phenomenon rather than mechanical processes, allowing us to interpret the position of the fossil parts as different moulting configurations. Since the trilobite assemblage seems to be in situ, the large number of exuviae suggests a local place of migration. This was triggered by the need for group protection while moulting, which is suggestive of gregarious behaviour, possibly synchronized. These trilobites from the Cambrian Epoch 2, Age 4 constitute one of the earliest known gregarious community of trilobites and has important implications for understanding the ecology of this group during their emergence in the Cambrian.

[Chloroxoquinoline inhibits invasion in breast cancer via down-regulating Rho/Rho kinase signaling pathway].

OBJECTIVE: To investigate the effect of chloroxoquinoline on cytoskeleton of breast cancer cells and its relation with Rho/Rho kinase signaling pathway. METHODS: Breast cancer Bcap37 and MDA-MB-453 cells were treated with different concentrations of chloroxoquinoline. Wound healing and Transwell assay were conducted to detect cell migration and invasion, respectively. Rhodamine-phalloidin staining and immunofluorescent staining were used to observe the polymerization state of F-actin and the expression of α-Tublin in breast cancer cells, respectively. Western blot was used to detect the phosphorylation level of key protein in Rho/Rho kinase signaling pathway. RESULTS: Compared with the control group, chloroxoquinoline treatment induced dose-dependent decrease in cell migration and invasion, and Bcap37 and MDA-MB-453 cells treated with chloroxoquinoline showed dose-dependent changes in cell morphology and decrease in cell body. The staining of F-actin and α-Tublin was irregular and clustered. Furthermore, treatment of chloroxoquinoline down-regulated the phosphorylation of the Rho/Rho kinase signaling proteins Cofilin, Limk and Rock2 (all P<0.01). CONCLUSIONS: Chloroxoquinoline inhibits the cytoskeleton in breast cancer Bcap37 and MDA-MB-453 cells and inhibits cell migration. This effect may be associated with down-regulation of Rho/Rho kinase signaling pathway.