In Amphioxus Embryos, Some Neural Tube Cells Resemble Differentiating Coronet Cells of Fishes and Tunicates.

AbstractFor neurula embryos of amphioxus (chordate subphylum Cephalochordata), the anterior region of the neural tube was studied with transmission electron microscopy. This survey demonstrated previously unreported cells, each characterized by a cilium bearing on its shaft a protruding lateral bubble packed with vesicles. Such cilia resemble those known from immature coronet cells in other chordates-namely, fishes in the Vertebrata and ascidians and appendicularians in the Tunicata.

Evolutionary assembly and disassembly of the mammalian sternum.

Evolutionary transitions are frequently associated with novel anatomical structures, but the origins of the structures themselves are often poorly known. We use developmental, genetic, and paleontological data to demonstrate that the therian sternum was assembled from pre-existing elements. Imaging of the perinatal mouse reveals two paired sternal elements, both composed primarily of cells with lateral plate mesoderm origin.

Activity Across the Lateral Somitic Frontier Regulates Development of the Mouse Sternum.

The skeletal system derives from multiple embryonic sources whose derivatives must develop in coordination to produce an integrated whole. In particular, interactions across the lateral somitic frontier, where derivatives of the somites and lateral plate mesoderm come into contact, are important for proper development. Many questions remain about genetic control of this coordination, and embryological information is incomplete for some structures that incorporate the frontier, including the sternum.

Thermal stress induces tissue damage and a broad shift in regenerative signaling pathways in the honey bee digestive tract.

Honey bee colonies in the USA have suffered from increased die-off in the last few years with a complex set of interacting stresses playing a key role. With changing climate, an increase in the frequency of severe weather events, such as heat waves, is anticipated. Understanding how these changes may contribute to stress in honey bees is crucial.

HOXA5 Participates in Brown Adipose Tissue and Epaxial Skeletal Muscle Patterning and in Brown Adipocyte Differentiation.

Brown adipose tissue (BAT) plays critical thermogenic, metabolic and endocrine roles in mammals, and aberrant BAT function is associated with metabolic disorders including obesity and diabetes. The major BAT depots are clustered at the neck and forelimb levels, and arise largely within the dermomyotome of somites, from a common progenitor with skeletal muscle. However, many aspects of BAT embryonic development are not well understood.

Detection of Gene and Protein Expression in Mouse Embryos and Tissue Sections.

Analysis of gene (mRNA and protein) expression patterns is central to the study of embryonic development. This chapter details methods for detecting mRNA and protein expression in whole-mouse embryos and in tissue sections, including mRNA in situ hybridization, immunohistochemistry, and detection of enzymatic and fluorescent protein reporters. We focus on histological methods; molecular methods of measuring gene expression (for example, RNAseq, PCR) are not included here.

HOXA5 protein expression and genetic fate mapping show lineage restriction in the developing musculoskeletal system.

HOX proteins act during development to regulate musculoskeletal morphology. HOXA5 patterns skeletal structures surrounding the cervical-thoracic transition including the vertebrae, ribs, sternum and forelimb girdle. However, the tissue types in which it acts to pattern the skeleton, and the ultimate fates of embryonic cells that activate Hoxa5 expression are unknown.

Paraffin Embedding and Thin Sectioning of Microbial Colony Biofilms for Microscopic Analysis.

Sectioning via paraffin embedding is a broadly established technique in eukaryotic systems. Here we provide a method for the fixation, embedding, and sectioning of intact microbial colony biofilms using perfused paraffin wax. To adapt this method for use on colony biofilms, we developed techniques for maintaining each sample on its growth substrate and laminating it with an agar overlayer, and added lysine to the fixative solution.

HOXA5 plays tissue-specific roles in the developing respiratory system.

is essential for development of several organs and tissues. In the respiratory system, loss of function causes neonatal death due to respiratory distress. Expression of HOXA5 protein in mesenchyme of the respiratory tract and in phrenic motor neurons of the central nervous system led us to address the individual contribution of these expression domains using a conditional gene targeting approach.

Multifaceted biological insights from a draft genome sequence of the tobacco hornworm moth, Manduca sexta.

Manduca sexta, known as the tobacco hornworm or Carolina sphinx moth, is a lepidopteran insect that is used extensively as a model system for research in insect biochemistry, physiology, neurobiology, development, and immunity. One important benefit of this species as an experimental model is its extremely large size, reaching more than 10 g in the larval stage. M.

A reference gene set for chemosensory receptor genes of Manduca sexta.

The order of Lepidoptera has historically been crucial for chemosensory research, with many important advances coming from the analysis of species like Bombyx mori or the tobacco hornworm, Manduca sexta. Specifically M. sexta has long been a major model species in the field, especially regarding the importance of olfaction in an ecological context, mainly the interaction with its host plants.

Independent regulation of vertebral number and vertebral identity by microRNA-196 paralogs.

The Hox genes play a central role in patterning the embryonic anterior-to-posterior axis. An important function of Hox activity in vertebrates is the specification of different vertebral morphologies, with an additional role in axis elongation emerging. The miR-196 family of microRNAs (miRNAs) are predicted to extensively target Hox 3' UTRs, although the full extent to which miR-196 regulates Hox expression dynamics and influences mammalian development remains to be elucidated.

Development of somites and their derivatives in amphioxus, and implications for the evolution of vertebrate somites.

Background: Vertebrate somites are subdivided into lineage compartments, each with distinct cell fates and evolutionary histories. Insights into somite evolution can come from studying amphioxus, the best extant approximation of the chordate ancestor. Amphioxus somites have myotome and non-myotome compartments, but development and fates of the latter are incompletely described.

Gustatory receptor neurons in Manduca sexta contain a TrpA1-dependent signaling pathway that integrates taste and temperature.

Temperature modulates the peripheral taste response of many animals, in part by activating transient receptor potential (Trp) cation channels. We hypothesized that temperature would also modulate peripheral taste responses in larval Manduca sexta. We recorded excitatory responses of the lateral and medial styloconic sensilla to chemical stimuli at 14, 22, and 30 °C.

Hoxa-5 acts in segmented somites to regulate cervical vertebral morphology.

The vertebrate axial skeleton (vertebral column and ribs) is derived from embryonic structures called somites. Mechanisms of somite formation and patterning are largely conserved along the length of the body axis, but segments acquire different morphologies in part through the action of Hox transcription factors. Although Hox genes' roles in axial skeletal patterning have been extensively characterized, it is still not well understood how they interact with somite patterning pathways to regulate different vertebral morphologies.

Identification of chemosensory receptor genes in Manduca sexta and knockdown by RNA interference.

Background: Insects detect environmental chemicals via a large and rapidly evolving family of chemosensory receptor proteins. Although our understanding of the molecular genetic basis for Drosophila chemoreception has increased enormously in the last decade, similar understanding in other insects remains limited. The tobacco hornworm, Manduca sexta, has long been an important model for insect chemosensation, particularly from ecological, behavioral, and physiological standpoints.

Evolution, expression, and developmental function of Hox-embedded miRNAs.

Exquisite regulation of Hox protein activity is fundamental to the regionalization of the early embryo across diverse taxa. Highlighting the critical importance of these transcription factors, an astonishing number of different mechanisms have evolved to tightly coordinate their activity both in time and in space. The recent identification of numerous microRNAs that are not only embedded within Hox clusters but also target numerous Hox genes suggests an important role for these regulatory molecules in shaping Hox protein output.

Detection of gene expression in mouse embryos and tissue sections.

Analysis of gene expression patterns is central to the study of embryonic development. This chapter details methods for detecting gene expression in whole mouse embryos and in tissue sections. The most commonly used methods available in mouse are described and include mRNA in situ hybridization, immunohistochemistry, and detection of enzymatic and fluorescent protein reporters.

Hox expression in the American alligator and evolution of archosaurian axial patterning.

The avian body plan has undergone many modifications, most associated with adaptation to flight and bipedal walking. Some of these modifications may be owing to avian-specific changes in the embryonic Hox expression code. Here, we have examined Hox expression in alligator, the closest living relative of birds, and an archosaur with a more conservative body plan.

In ovo application of antagomiRs indicates a role for miR-196 in patterning the chick axial skeleton through Hox gene regulation.

Patterning of the vertebrate axial skeleton requires precise spatial and temporal control of Hox gene expression during embryonic development. MicroRNAs (miRNAs) are recently described modulators of gene activity, and members of the miR-196 and miR-10 families have been shown to target several Hox genes in vivo. Testing miRNA function in mice is complicated by potential redundancy between family members.

The microRNA miR-196 acts upstream of Hoxb8 and Shh in limb development.

MicroRNAs (miRNAs) are an abundant class of gene regulatory molecules (reviewed in refs 1, 2). Although computational work indicates that miRNAs repress more than a third of human genes, their roles in vertebrate development are only now beginning to be determined. Here we show that miR-196 acts upstream of Hoxb8 and Sonic hedgehog (Shh) in vivo in the context of limb development, thereby identifying a previously observed but uncharacterized inhibitory activity that operates specifically in the hindlimb.

The RNaseIII enzyme Dicer is required for morphogenesis but not patterning of the vertebrate limb.

The RNaseIII-containing enzyme Dicer is believed to be required for the processing of most, if not all, microRNAs (miRNAs) and for processing long dsRNA into small interfering RNAs. Because the complete loss of Dicer in both zebrafish and mice results in early embryonic lethality, it has been impossible to determine what role, if any, Dicer has in patterning later tissues in the developing vertebrate embryo. To bypass the early requirement of Dicer in development, we have created a conditional allele of this gene in mice.