Vertical and horizontal distributions of major meiofauna taxa on selected beaches in the South Slough Estuary, Charleston, Oregon, USA

The purpose of this study was to compare the differences in abundance of Nematoda, Gastrotricha, and Harpacticoida between depths in the sediment at various tide levels and between depths at various sites with increasing time of exposure. It also examines the relationship between the abundances of meiofaunal groups and the mean grain size of the sediment. This study was also a part of the continual baseline-data gathering program for the South Slough Estuarine Sanctuary, Delane A. Munson, Manager

Sea Ice Type and Open Water Discrimination for Operational Ice Monitoring with RADARSAT-2

Abstract-Envisat ASAR Alternating Polarization (AP) modes are evaluated to determine the potential utility of multi-polarization data for operational sea ice monitoring in preparation for RADARSAT-2

Medusan Morphospace: Phylogenetic Constraints, Biomechanical Solutions, and Ecological Consequences

Medusae were the earliest animals to evolve muscle-powered swimming in the seas. Although medusae have achieved diverse and prominent ecological roles throughout the world\u27s oceans, we argue that the primitive organization of cnidarian muscle tissue limits force production and, hence, the mechanical alternatives for swimming bell function. We use a recently developed model comparing the potential force production with the hydrodynamic requirements of jet propulsion, and conclude that jet production is possible only at relatively small bell diameters. In contrast, production of a more complex wake via what we term rowing propulsion permits much larger sizes but requires a different suite of morphological features. Analysis of morphometric data from all medusan taxa independently confirms size-dependent patterns of bell forms that correspond with model predictions. Further, morphospace analysis indicates that various lineages within the Medusozoa have proceeded along either of two evolutionary trajectories. The first alternative involved restriction of jet-propelled medusan bell diameters to small dimensions. These medusae may be either solitary individuals (characteristic of Anthomedusae and Trachymedusae) or aggregates of small individual medusan units into larger colonial forms (characteristic of the nectophores of many members of the Siphonophorae). The second trajectory involved use of rowing propulsion (characteristic of Scyphozoa and some hydromedusan lineages such as the Leptomedusae and Narcomedusae) that allows much larger bell sizes. Convergence on either of the differing propulsive alternatives within the Medusozoa has emerged via parallel evolution among different medusan lineages. The distinctions between propulsive modes have important ecological ramifications because swimming and foraging are interdependent activities for medusae. Rowing swimmers are characteristically cruising predators that select different prey types from those selected by jet-propelled medusae, which are predominantly ambush predators. These relationships indicate that the different biomechanical solutions to constraints on bell function have entailed ecological consequences that are evident in the prey selection patterns and trophic impacts of contemporary medusan lineages

Human Myoblast Fusion Requires Expression of Functional Inward Rectifier Kir2.1 Channels

Myoblast fusion is essential to skeletal muscle development and repair. We have demonstrated previously that human myoblasts hyperpolarize, before fusion, through the sequential expression of two K+ channels: an ether-à-go-go and an inward rectifier. This hyperpolarization is a prerequisite for fusion, as it sets the resting membrane potential in a range at which Ca2+ can enter myoblasts and thereby trigger fusion via a window current through α1H T channels

THE SHADOW RESPONSE OF A. HYDROMEDUSAN (POLYORCHIS PENICILLATUS): BEHAVIORAL MECHANISMS CONTROLLING DIEL AND ONTOGENIC VERTICAL MIGRATION

Volume: 169Start Page: 297End Page: 31

Vertical and horizontal distributions of major meiofauna taxa on selected beaches in the South Slough Estuary, Charleston, Oregon, USA

The purpose of this study was to compare the differences in abundance of Nematoda, Gastrotricha, and Harpacticoida between depths in the sediment at various tide levels and between depths at various sites with increasing time of exposure. It also examines the relationship between the abundances of meiofaunal groups and the mean grain size of the sediment. This study was also a part of the continual baseline-data gathering program for the South Slough Estuarine Sanctuary, Delane A. Munson, Manager

NEURONAL CONTROL OF CILIARY LOCOMOTION IN A GASTROPOD VELIGER (CALLIOSTOMA)

Volume: 173Start Page: 513End Page: 52