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The article focuses on evolutionary biology. Despite the comforting certainty of textbooks and 150 years of argument, the true relationships of the major groups of animals remain contentious. In the late 1990s, a series of controversial papers used molecular evidence to propose a radical rearrangement of animal phylum. Traditional trees group together phyla of bilaterally symmetrical animals that possess a body cavity lined with mesodermal tissue, the coelom, as Coelomata. Those without a true coelom are classified as Acoelomata and Pseudocoelomata.

As a central model for morphogen action during animal development, the bone morphogenetic protein 2/4 (BMP2/4)-like ligand Decapentaplegic (Dpp) is proposed to form a long-range signalling gradient that directs both growth and pattern formation during Drosophila wing disc development. While the patterning role of Dpp secreted from a stripe of cells along the anterior-posterior compartmental boundary is well established, the mechanism by which a Dpp gradient directs uniform cell proliferation remains controversial and poorly understood. Here, to determine the precise spatiotemporal requirements for Dpp during wing disc development, we use CRISPR-Cas9-mediated genome editing to generate a flippase recognition target (FRT)-dependent conditional null allele. By genetically removing Dpp from its endogenous stripe domain, we confirm the requirement of Dpp for the activation of a downstream phospho-Mothers against dpp (p-Mad) gradient and the regulation of the patterning targets spalt (sal), optomotor blind (omb; also known as bifid) and brinker (brk). Surprisingly, however, third-instar wing blade primordia devoid of compartmental dpp expression maintain relatively normal rates of cell proliferation and exhibit only mild defects in growth. These results indicate that during the latter half of larval development, the Dpp morphogen gradient emanating from the anterior-posterior compartment boundary is not directly required for wing disc growth. [ABSTRACT FROM AUTHOR]

The article reports on the discovery of turtle and chelonian shell formation. It has been discovered that turtles' shells are developed from the above ribcage, tucking their shoulder blades under the edges of the ribs. The formation of their ribs are underdeveloped, as compared to those of mice and chicken.

The mouse genetic revolution has shown repeatedly that most organs have more functions than expected. This has led to the realization that, in addition to a molecular and cellular approach, there is a need for a whole-organism study of physiology. The skeleton is an example of how a whole-organism approach to physiology can broaden the functions of a given organ, reveal connections of this organ with others such as the brain, pancreas and gut, and shed new light on the pathogenesis of degenerative diseases affecting multiple organs. [ABSTRACT FROM AUTHOR]

The spectacular escalation in complexity in early bilaterian evolution correlates with a strong increase in the number of microRNAs. To explore the link between the birth of ancient microRNAs and body plan evolution, we set out to determine the ancient sites of activity of conserved bilaterian microRNA families in a comparative approach. We reason that any specific localization shared between protostomes and deuterostomes (the two major superphyla of bilaterian animals) should probably reflect an ancient specificity of that microRNA in their last common ancestor. Here, we investigate the expression of conserved bilaterian microRNAs in Platynereis dumerilii, a protostome retaining ancestral bilaterian features, in Capitella, another marine annelid, in the sea urchin Strongylocentrotus, a deuterostome, and in sea anemone Nematostella, representing an outgroup to the bilaterians. Our comparative data indicate that the oldest known animal microRNA, miR-100, and the related miR-125 and let-7 were initially active in neurosecretory cells located around the mouth. Other sets of ancient microRNAs were first present in locomotor ciliated cells, specific brain centres, or, more broadly, one of four major organ systems: central nervous system, sensory tissue, musculature and gut. These findings reveal that microRNA evolution and the establishment of tissue identities were closely coupled in bilaterian evolution. Also, they outline a minimum set of cell types and tissues that existed in the protostome–deuterostome ancestor. [ABSTRACT FROM AUTHOR]

Do new anatomical structures arise de novo, or do they evolve from pre-existing structures? Advances in developmental genetics, palaeontology and evolutionary developmental biology have recently shed light on the origins of some of the structures that most intrigued Charles Darwin, including animal eyes, tetrapod limbs and giant beetle horns. In each case, structures arose by the modification of pre-existing genetic regulatory circuits established in early metazoans. The deep homology of generative processes and cell-type specification mechanisms in animal development has provided the foundation for the independent evolution of a great variety of structures. [ABSTRACT FROM AUTHOR]

Regulatory T cells (Treg) expressing the transcription factor Foxp3 control the autoreactive components of the immune system. The development of Treg cells is reciprocally related to that of pro-inflammatory T cells producing interleukin-17 (TH17). Although Treg cell dysfunction and/or TH17 cell dysregulation are thought to contribute to the development of autoimmune disorders, little is known about the physiological pathways that control the generation of these cell lineages. Here we report the identification of the ligand-activated transcription factor aryl hydrocarbon receptor (AHR) as a regulator of Treg and TH17 cell differentiation in mice. AHR activation by its ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin induced functional Treg cells that suppressed experimental autoimmune encephalomyelitis. On the other hand, AHR activation by 6-formylindolo[3,2-b]carbazole interfered with Treg cell development, boosted TH17 cell differentiation and increased the severity of experimental autoimmune encephalomyelitis in mice. Thus, AHR regulates both Treg and TH17 cell differentiation in a ligand-specific fashion, constituting a unique target for therapeutic immunomodulation. [ABSTRACT FROM AUTHOR]

Morphological, molecular, and biogeographic data bearing on early primate evolution suggest that the clade containing extant (or 'crown') strepsirrhine primates (lemurs, lorises and galagos) arose in Afro-Arabia during the early Palaeogene, but over a century of palaeontological exploration on that landmass has failed to uncover any conclusive support for that hypothesis. Here we describe the first demonstrable crown strepsirrhines from the Afro-Arabian Palaeogene-a galagid and a possible lorisid from the late middle Eocene of Egypt, the latter of which provides the earliest fossil evidence for the distinctive strepsirrhine toothcomb. These discoveries approximately double the previous temporal range of undoubted lorisiforms and lend the first strong palaeontological support to the hypothesis of an ancient Afro-Arabian origin for crown Strepsirrhini and an Eocene divergence of extant lorisiform families. [ABSTRACT FROM AUTHOR]

Salamanders are a model system for studying the rates and patterns of the evolution of new anatomical structures. Recent discoveries of abundant Late Jurassic and Early Cretaceous salamanders are helping to address these issues. Here we report the discovery of well-preserved Middle Jurassic salamanders from China, which constitutes the earliest known record of crown-group urodeles (living salamanders and their closest relatives). The new specimens are from the volcanic deposits of the Jiulongshan Formation (Bathonian), Inner Mongolia, China, and represent basal members of the Cryptobranchidae, a family that includes the endangered Asian giant salamander (Andrias) and the North American hellbender (Cryptobranchus). These fossils document a Mesozoic record of the Cryptobranchidae, predating the previous record of the group by some 100 million years. This discovery provides evidence to support the hypothesis that the divergence of the Cryptobranchidae from the Hynobiidae had taken place in Asia before the Middle Jurassic period. [ABSTRACT FROM AUTHOR]

Describes observations of the filamentous integumental appendages of the basal dromaeosaurid dinosaur Sinornithosaurus millenii. Indication that they are compound structures composed of multiple filaments; Exhibition of two types of branching structure unique to avian feathers, filaments joined in a basal tuft and filaments joined at their bases in series along a central filament; Agreement with predictions of an independent, developmental model of the evolutionary origin of feathers.

Reports that the Drosophila segment polarity genes constitute a module that is resistant to variations in the kinetic constants that govern its behavior. Background on insects and the segment specification in various orders; Questions regarding segmentation; Details and conclusions of the study.

Presents research which described a new therizinosauroid, or Asian dinosaur, from the Yixian Formation, Early Cretaceous period, in Liaoning, China. Affinities of the dinosaur with other dinosaurs; New taxon located in the coelurosaurian theropods; Traits of the dinosaur; Implications for the distribution of feather-like structures among non-avian theropods.

Presents research which described Late Triassic therapod trackways from East Greenland. Use of dinosaur footprints as biostratigraphic markers; Studied trackways providing three-dimensional records of foot movement; Prints compared with those of ground-dwelling birds.

Discusses the author's use of radiographs and computed tomography to show that many unique human features stem partly from a single, ontogenetically early reduction in the length of the sphenoid, the central bone of the cranial base from which the face grows forward. Sphenoid reduction accounting for the rapid evolution of modern human cranial form; Suggestion that Neanderthals and other archaic Homo should be excluded from Homo sapiens.

Presents research which studied a skeleton of a species of the basal pterosaur Dimorphodon from Tamaulipas, Mexico. Controversy about nature of the hindlimb posture and gait of pterosaurs; Extent to which pterosaurs moved on the ground; Skeleton including a three-dimensional foot; Flattened metatarsal-phalangeal joint of skeleton; Determination of flat-footed stance.

Presents research which suggests that if strong, directed loops in the cortical areas of macaque monkeys were to exist, the cortex would go into uncontrolled oscillations. Distinct areas of macaque monkey visual system; Nature of connections in system; Digraphs; Visual thalamus; Thalamic projections to the cortex; Theory; Possible generalizations; Discussion; Conclusions.