A Novel Imaging Protocol for Investigating Siliques and Seeds Using X-rays.

Understanding silique and seed morphology is essential to developmental biology. Arabidopsis thaliana is one of the best-studied plant models for understanding the genetic determinants of seed count and size. However, the small size of its seeds, and their encasement in a pod known as silique, makes investigating their numbers and morphology both time consuming and tedious.

Evolution of a chordate-specific mechanism for myoblast fusion.

Vertebrate myoblast fusion allows for multinucleated muscle fibers to compound the size and strength of mononucleated cells, but the evolution of this important process is unknown. We investigated the evolutionary origins and function of membrane-coalescing agents Myomaker and Myomixer in various groups of chordates. Here, we report that likely arose through gene duplication in the last common ancestor of tunicates and vertebrates, while appears to have evolved de novo in early vertebrates.

Comparative biomechanics of hagfish skins: diversity in material, morphology, and movement.

The baggy skins of hagfishes confer whole-body flexibility that enables these animals to tie themselves into knots without injury. The skin's looseness is produced by a subcutaneous blood sinus that decouples the skin and body core and permits the core to contort dramatically without loading the skin in tension or shear. Hagfish skin represents a biological composite material comparable in strength and stiffness to the conventionally taut skins of other fishes.

Powering the hagfish "bite": The functional morphology of the retractor complex of two hagfish feeding apparatuses.

Hagfish use forceful retractions of a dental plate to shear and ingest food. Retractile force is generated by the retractor muscle complex of the posterior hagfish feeding apparatus (HFA). While gross morphological descriptions exist, the organization of muscle and connective tissue fibers that form the soft tissue retractor complex do not.

Material Properties of Hagfish Skin, with Insights into Knotting Behaviors.

Hagfishes (Myxinidae) often integrate whole-body knotting movements with jawless biting motions when reducing large marine carcasses to ingestible items. Adaptations for these behaviors include complex arrangements of axial muscles and flexible, elongate bodies without vertebrae. Between the axial muscles and the hagfish skin is a large, blood-filled subcutaneous sinus devoid of the intricate, myoseptal tendon networks characteristic of the taut skins of other fishes.

The structure and function of a muscle articulation-type jaw joint of a polychaete worm.

The arrangement of the musculature and the fibers of the extracellular matrix (ECM) in the flexible jaw joint of the sandworm Alitta virens (Annelida, Polychaeta) was studied using dissection and histology. The jaws are capable of a wide range of motions principally related to defense and feeding. The left and right jaws are embedded in and moved by a compact pharyngeal bulb of muscle and ECM that also forms the mouth and esophagus.

What is the role of titin in active muscle?

Several properties of muscle defy explanation solely based on the sliding filament-swinging cross-bridge theory. Indeed, muscle behaves as though there is a dynamic "spring" within the sarcomeres. We propose a new "winding filament" mechanism for how titin acts, in conjunction with the cross-bridges, as a force-dependent spring.

Morphology of the muscle articulation joint between the hooks of a flatworm (Kalyptorhynchia, Cheliplana sp.).

Schizorhynch kalyptorhynchs are meiofaunal turbellarian predators that possess an eversible proboscis that can be armed with two stout hooks. The hooks grasp and manipulate prey using a wide range of rotations and translations. These diverse motions are possible because the hook supports may function as a muscle articulation type joint-that is, a joint formed of muscle and connective tissue that connects, separates, and moves the microscopic hooks.

Electromyography of the buccal musculature of octopus (Octopus bimaculoides): a test of the function of the muscle articulation in support and movement.

The buccal mass musculature of the octopus (Octopus bimaculoides) was studied with electromyography to test the predictions of a previous morphological study in which we suggested that the muscles of the buccal mass serve as both the effectors of movement and as the joint itself, forming a new category of flexible joint termed a ;muscle articulation'. The predictions of muscle function were tested by correlating muscle electrical activity in isolated buccal masses with spontaneous beak movements. Bipolar electromyography electrodes were implanted in the various beak muscles and beak position was recorded simultaneously with an electronic movement monitor (N=14).

Functional morphology of the cephalopod buccal mass: a novel joint type.

The arrangement of the musculature and connective tissues of the buccal mass of the coleoid cephalopods Octopus bimaculoides, Sepia officinalis, and Loliguncula brevis was examined using dissection and histology. Serial sections in three mutually perpendicular planes were used to identify the muscles and connective tissues responsible for beak movements and stability and to describe their morphology and fiber trajectories. Four major beak muscles were identified: the anterior, posterior, superior, and lateral mandibular muscles.