Cusp-based geometric height-oriented repair of a pediatric aortic valve

Progressive aortic regurgitation can occur in pediatric patients due to root dilation with conotruncal anomalies or cusp prolapse associated with a ventricular septal defect. It is treated using various approaches influenced by personal preferences and institutional experience. We applied geometrical concepts developed for adult aortic valve repair to pediatric valves. The basal ring and sinotubular junction are downsized in relation to the geometric height of the cusp by external suture annuloplasty. The length of the cusp free margin is then adjusted with central plication, guided by measuring the effective height of the cusp. This approach facilitates the reproducibility and predictability of pediatric aortic valve repair.

Growth rates and crown morphology of Abies amabilis in the seedling bank of an ancient subalpine conifer forest

The population dynamics of shade-tolerant tree species often includes a seedling bank — small trees persisting in the understory until canopy opening allows increased height growth. We studied the growth and morphology of 0.1–1.3 m tall Abies amabilis Douglas ex J. Forbes trees in the seedling bank of an ancient (>1300 years old) subalpine conifer forest on Vancouver Island, western Canada. We determined rates of height growth by counting growth rings at 10 cm intervals along the main stem and assessed crown morphology by measuring the length and location of each branch along the main stem. These small trees were very old (mean basal ring count, 112 years) and grew very slowly, taking on average 170 years to reach a height of 1 m. Instead of the typical conical form of open-grown Abies Mill., seedling bank individuals had flat crowns. Most branches were near the top of the main stem. The maximum distance along the main stem plus a branch was 1.6 times the main stem length, indicating that resource allocation is focused on lateral growth. The ability to grow slowly and adjust crown morphology allows seedling bank trees to persist for decades to centuries and to retain the possibility of release and growth into the canopy.

Serial Section-Based 3D Reconstruction of Anaxagorea (Annonaceae) Carpel Vasculature and Implications on Integrated Axial-Foliar Origin of Angiosperm Carpels

The carpel is the basic unit of the gynoecium in angiosperms and one of the most important morphological features distinguishing angiosperms from gymnosperms; therefore, carpel origin is of great significance in angiosperm phylogenetic origin. Recent consensus favors the interpretation that the carpel originates from the fusion of an ovule-bearing axis and the phyllome that subtends it. It has been confirmed by morphological and molecular evidence that foliar homologs are involved in carpel evolution. Consequently, if axial homologs can be traced in the carpel, it would more likely be derived from an integrated axial-foliar structure. This study aimed to reveal the axial structures in carpels by analyzing the continuous changes in vasculature from the receptacle to the carpels and ovules. Anaxagorea is the most basal genus in a primitive angiosperm family, Annonaceae. The conspicuous carpel stipe at the base of each carpel makes it an ideal material for exploring the possible axial homologous structure in the carpel. In this study, floral organogenesis and the topological vasculature structure were delineated in Anaxagorea luzonensis and Anaxagorea javanica, and a 3D-model of the carpel vasculature was reconstructed based on the serial sections. The results show that (1) at the flowering stage, the number of vascular bundles entering each Anaxagorea carpel from the receptacle was significantly higher than three, arranged in a radiosymmetric pattern, and forming a basal ring at the base of each carpel. (2) All carpel bundles were only connected with the central stele. (3) At the slightly upper part of the carpel, all lateral bundles from the basal ring were reorganized into two groups, each forming a lateral bundle complex below the respective placenta. Bundles in each lateral bundle complex were also ringed. (4) The ovule bundles were composed of non-adjacent bundles in the lateral bundle complex. The results of the present study suggest that the circular arrangement of bundles in the receptacle, carpel stipe, and placenta of Anaxagorea are in line with the composite axial-foliar nature of the carpel, and provide a morphological basis for further research on the origin of the carpel.

Sperm ultrastructure in the ocean quahog Arctica islandica (Arcticidae) and Neotrapezium sublaevigatum (Trapezidae), with a discussion of relationships within the Arcticoidea and with other Euheterodonta (Bivalvia)

ABSTRACT Sperm ultrastructure is described for the ocean quahog Arctica islandica (Linnaeus, 1767) (Arcticidae), a long-lived, and commercially and phylogenetically important marine bivalve from the North Atlantic, and for Neotrapezium sublaevigatum (Lamarck, 1819), an Indo-Pacific member of the only other family of Arcticoidea (Trapezidae). Spermatozoa of A. islandica consist of (in anterior to posterior sequence): an elongate-conical, deeply invaginated, acrosomal vesicle (length 2.0 ± 0.2 μm; invagination occupied by a granular subacrosomal material); a straight, anteriorly-tapered, rod-shaped nucleus (length 6.6 ± 0.4 μm); a short (approximately 0.8 μm) midpiece consisting of two orthogonally arranged centrioles, surrounded by four (approximately 75% of spermatozoa observed) or, less commonly, five (approximately 25% of spermatozoa observed) spherical mitochondria; nine satellite fibres connecting the distal centriole to mitochondria and the plasma membrane; and a flagellum (length 60 ± 5.0 μm, with 9+2 axoneme), originating from the distal centriole. Contents of the acrosomal vesicle of A. islandica are differentiated into a very electron-dense basal ring (with reticulate structure) and two less electron-dense zones. Spermatozoa of N. laevigatum (Lamarck, 1819) differ substantially from those of A. islandica and are characterized by: a rounded-conical, deeply invaginated, acrosomal vesicle (length 0.43 ± 0.2 μm), with a curved basal ring and two less conspicuous components; a barrel-shaped nucleus (length 1.6 ± 0.5 μm) with a broad apical depression accommodating the base of the acrosomal vesicle; a midpiece composed of five (approximately 80% of spermatozoa observed) or four (approximately 20% of spermatozoa observed) mitochondria. Centriolar and flagellar details are essentially as for A. islandica, and putative glycogen deposits are associated with the distal centriole and mitochondria in both species. Sperm data corroborate recent transcriptomic analyses separating Arcticidae and Trapezidae in different imparidentian clades. Based on sperm morphology, A. islandica would appear more closely related to the Glauconomidae of the Cyrenoidea than to the Trapezidae, Veneroidea or any other previously examined group of euheterodonts, suggesting that it could be the only living member of the Arcticoidea. The relationships of the Trapezidae remain uncertain, with apparent sperm similarities to members of several groups of euheterodonts (e.g. Tellinoidea, Pholadoidea, Galeommatoidea), while several potentially closely related key taxa (e.g. Glossidae) remain unstudied for sperm characters.

A new species of Procamallanus Baylis, 1923 (Nematoda, Camallanidae) from Astronotus ocellatus (Agassiz, 1831) (Perciformes, Cichlidae) in Brazil

A new species ofProcamallanusBaylis, 1923 was found as a parasite of the fishAstronotusocellatus(Agassiz, 1831) from a lake in the Jardim Botânico Bosque Rodrigues Alves, Belém, Brazil.Procamallanusspiculastriatussp. n.has a smooth buccal capsule and a well-developed basal ring that is armed with four sclerotized tooth-like structures. The male of the new species is similar to the two species that are known from Brazilian fish,P.peraccuratusPinto, Fábio, Noronha & Rolas, 1976, andP.annipetteraeKohn & Fernandes, 1988, by the absence of the gubernaculum. It differs from these two by the morphology of the buccal capsule, the number are arrangement of the caudal papillae in males, the size and morphology of the spicules and the shape of the tail of both sexes.Procamallanusspiculastriatussp. n.is the third species discovered in fish from Brazil. This finding extends the geographical distribution of the genus into the Brazilian Amazon.

Morphometric analysis of early Eocene <i>Corbisema</i> skeletons (Silicoflagellata) in Mors, Denmark

A two-dimensional morphometric programme, recently designed to measure fossil skeletons of the silicoflagellate genus Corbisema, was used to investigate specimens of the C. apiculata–C. triacantha complex found in a sample from the Fur Formation on the island of Mors, Jutland, Denmark. The semi-automated programme measured the lengths of the basal sides and radial spines, the basal side curvature, and the location of the pikes (if present) from a photographic database (N=469). As a result, two distinct morphological groups were revealed based on their radial spine length : basal side length ratio and the presence or absence of pikes: group A (ratio of 1 : 1.3, no pikes) and group B, with the latter subdivided into B1 (ratio of 1 : 7, with pikes) and B2 (ratio of 1 : 6, no pikes). Group A (C. triacantha sensu lato) possesses a small basal ring with relatively straight basal sides and long radial spines, while group B has a large basal ring with curved basal sides and short radial spines. In B1 specimens (C. apiculata sensu stricto) the pikes are positioned 0 to 1 µm away from the junction point of the strut and basal ring. This would suggest that B1 double skeletons are likely to be in the Star-of-David configuration, while A and B2 double skeletons (which lack pikes) are likely to be in the corner-to-corner configuration. Compared with the previously published biometric studies of extant Stephanocha (Stephanocha speculum complex in the Southern Ocean and S. medianoctisol in the Arctic Ocean), the results are somewhat different: although C. triacantha sensu lato (group A) is similar to the modern species of Stephanocha, the latter have smaller basal ring diameters, whereas specimens of C. apiculata sensu lato (types B1 and B2) have large basal rings. If their cell diameters are calculated, B1 is the largest, with S. speculum being the smallest – about half the size of B1. This could suggest that the relationship between radial spine length and mean basal ring size has shifted over geological time.