Saprobic Dothideomycetes in Thailand: Phaeoseptum hydei sp. nov., a new terrestrial ascomycete in Phaeoseptaceae

During a survey of saprobic microfungi in Thailand, a dothideomycetous fungus was found on a dead twig of Delonix regia, on the Chiang Mai University campus. This fungus is characterized by fully immersed ascomata under a small blackened pseudoclypeus, pseudoparenchymatous peridium, cellular pseudoparaphyses, cylindrical-clavate asci with a distinct pedicel, overlapping 3–4-seriate, pale to dark brown, broadly fusoid, 7–9-transversally septate ascospores with a vertical septum in nearly all median cells. Multigene phylogenetic analyses, using partial sequences from the 28S nrRNA gene (LSU), 18S nrRNA gene (SSU), internal transcribed spacer regions and intervening 5.8S nrRNA gene (ITS) of the nrDNA operon and the translation elongation factor 1-alpha region (TEF) demonstrated a monophyletic affiliation of the new strain, accommodating the species of Phaeoseptum in the family Phaeoseptaceae. With further morphological and phylogenetic investigations, we justify the new fungus as a novel species, Phaeoseptum hydei in Phaeoseptaceae. Detailed descriptions and illustrations are provided for Phaeoseptum hydei and this novel species compared with the remaining species found in the genus. An updated checklist of microfungi recorded on Delonix regia from around the world is also provided.

Heart development in the lizards (Varanidae) with the greatest extent of ventricular septation

Among lizards, only monitor lizards (Varanidae) have a functionally divided cardiac ventricle. This enables them to sustain higher systemic blood pressures and higher metabolic rates than other reptiles of similar size. The division results from the concerted action of three partial septa, which may have homology to the full ventricular septum of mammals and archosaurs. Homology, however has only been inferred from anatomical comparisons of hearts of adult monitors whereas gene expression during heart development has not been studied. We show in developing monitors that the partial septa that separate the left and right ventricle, the ‘muscular ridge’ and ‘bulbuslamelle’, express the evolutionary conserved transcription factors Tbx5, Irx1 and Irx2, orthologues of which mark the full ventricular septum. Compaction of embryonic trabeculae contributes to the formation of these septa. The septa are positioned, however, to the right of the atrioventricular junction and they do not partake in the separation of incoming atrial blood streams. Instead, the ‘vertical septum’ within the left ventricle separates the atrial blood streams. It expresses Tbx3 and Tbx5, which orchestrate the formation of the electrical conduction axis of the full ventricular septum. These patterns of expression are more pronounced in monitors than in other lizards, and are associated with a deep electrical activation near the vertical septum, contrasting the primitive base-to-apex activation of other lizards. We conclude that current concepts of ventricular septum formation apply well to the monitor septa and that there is evolutionary conservation of ventricular septum formation among amniote vertebrates.

Regional variation in the mechanical properties of the vertebral column during lateral bending in Morone saxatilis

Unlike mammalian, disc-shaped intervertebral joints (IVJs), the IVJs in fishes are biconid structures, filled with fluid and thought to act as hydrostatic hinge joints during swimming. However, it remains unclear which IVJ structures are dominant in mechanical resistance to forces in fishes, and whether variation in these tissues might impact the function of the vertebral column along its length. Here, we measured the dynamic mechanical behaviour of IVJs from striped bass, Morone saxatilis . During lateral bending, angular stiffness was significantly lower in the caudal and cervical regions, relative to the abdominal region. The neutral zone, defined as the range of motion (ROM) at bending moments less than 0.001 Nm, was longer in the caudal relative to the abdominal IVJs. Hysteresis was 30–40% in all regions, suggesting that IVJs may play a role in energy dissipation during swimming. Cutting the vertical septum had no statistically significant effect, but cutting the encapsulating tissues caused a sharp decline in angular stiffness and a substantial increase in ROM and hysteresis. We conclude that stiffness decreases and ROM increases from cranial to caudal in striped bass, and that the encapsulating tissues play a prominent role in mechanical variation along the length of the vertebral column.

Inspired by Sharks: A Biomimetic Skeleton for the Flapping, Propulsive Tail of an Aquatic Robot

The vertebral column is the primary stiffening element of the body of fish. This serially jointed axial support system offers mechanical control of body bending through kinematic constraint and viscoelastic behavior. Because of the functional importance of the vertebral column in the body undulations that power swimming, we targeted the vertebral column of cartilaginous fishes—sharks, skates, and rays—for biomimetic replication. We examined the anatomy and mechanical properties of shark vertebral columns. Based on the vertebral anatomy, we built two classes of biomimetic vertebral column (BVC): (1) one in which the shape of the vertebrae varied and all else was held constant and (2) one in which the axial length of the invertebral joint varied and all else was held constant. Viscoelastic properties of the BVCs were compared to those of sharks at physiological bending frequencies. The BVCs with variable joint lengths were then used to build a propulsive tail, consisting of the BVC, a vertical septum, and a rigid caudal fin. The tail, in turn, was used as the propeller in a surface-swimming robot that was itself modeled after a biological system. As the BVC becomes stiffer, swimming speed of the robot increases, all else being equal. In addition, stiffer BVCs give the robot a longer stride length, the distance traveled in one cycle of the flapping tail.

A description of the baculum of the bobcat (Felis rufus), with comments on its development and taxonomic implications

Examination of the genitalia of male bobcats collected in Arkansas revealed the common occurrence of bacula. The preformed architecture of dense connective tissue and cartilage was evident in juveniles (<1 year). Observed morphological variation in adults was partially ascribed to ontogeny. Maximum dimensions observed were 7.6 mm (length) and 3.1 mm (width). The distal portion of the baculum is a narrow shaft, while the proximal region is expanded and bifurcated ventrally. A vertical septum separates two vacuities in the base of the baculum. These vacuities house the primarily adipose ends of the corpora cavernosa. Morphology of the baculum of the bobcat is similar to that of the European lynx, and, while different from other felids, it indicates validity of the genus Lynx.

Collection of urine from each kidney in the rabbit without ureteral cannulation

Collection of urine in rabbits by conventional methods such as catheterization of ureters or bladder with polyethylene tubing or Foley cannulas is hampered by the occurrence of hematuria or obstruction of urine flow, or both. These problems were solved by placing in the bladder a stainless steel device with a horizontal round disk attached to an eliptic vertical septum. The vertical septum divides the bladder into two compartments in such a way as to allow the collection of urine from each kidney. Studies show that this intrabladder devide can be satisfactorily used in acute experiments in anesthetized or conscious rabbits for periods up to 5–6 h.