Comparable Ages for the Independent Origins of Electrogenesis in African and South American Weakly Electric Fishes

One of the most remarkable examples of convergent evolution among vertebrates is illustrated by the independent origins of an active electric sense in South American and African weakly electric fishes, the Gymnotiformes and Mormyroidea, respectively. These groups independently evolved similar complex systems for object localization and communication via the generation and reception of weak electric fields. While good estimates of divergence times are critical to understanding the temporal context for the evolution and diversification of these two groups, their respective ages have been difficult to estimate due to the absence of an informative fossil record, use of strict molecular clock models in previous studies, and/or incomplete taxonomic sampling. Here, we examine the timing of the origins of the Gymnotiformes and the Mormyroidea using complete mitogenome sequences and a parametric Bayesian method for divergence time reconstruction. Under two different fossil-based calibration methods, we estimated similar ages for the independent origins of the Mormyroidea and Gymnotiformes. Our absolute estimates for the origins of these groups either slightly postdate, or just predate, the final separation of Africa and South America by continental drift. The most recent common ancestor of the Mormyroidea and Gymnotiformes was found to be a non-electrogenic basal teleost living more than 85 millions years earlier. For both electric fish lineages, we also estimated similar intervals (16–19 or 22–26 million years, depending on calibration method) between the appearance of electroreception and the origin of myogenic electric organs, providing rough upper estimates for the time periods during which these complex electric organs evolved de novo from skeletal muscle precursors. The fact that the Gymnotiformes and Mormyroidea are of similar age enhances the comparative value of the weakly electric fish system for investigating pathways to evolutionary novelty, as well as the influences of key innovations in communication on the process of species radiation

人間の海洋移動にともなう分散がフィリピン列島における媒介蚊ネッタイシマ蚊の集団遺伝構造に影響

長崎大学学位論文 [学位記番号]博（医歯薬）甲第794号 [学位授与年月日]平成27年9月18

What can whiskers tell us about mammalian evolution, behaviour, and ecology?

Most mammals have whiskers; however, nearly everything we know about whiskers derives from just a handful of species, including laboratory rats Rattus norvegicus and mice Mus musculus, as well as some species of pinniped and marsupial. We explore the extent to which the knowledge of the whisker system from a handful of species applies to mammals generally. This will help us understand whisker evolution and function, in order to gain more insights into mammalian behaviour and ecology. This review is structured around Tinbergen’s four questions, since this method is an established, comprehensive, and logical approach to studying behaviour. We ask: how do whiskers work, develop, and evolve? And what are they for? While whiskers are all slender, curved, tapered, keratinised hairs that transmit vibrotactile information, we show that there are marked differences between species with respect to whisker arrangement, numbers, length, musculature, development, and growth cycles. The conservation of form and a common muscle architecture in mammals suggests that early mammals had whiskers. Whiskers may have been functional even in therapsids. However, certain extant mammalian species are equipped with especially long and sensitive whiskers, in particular nocturnal, arboreal species, and aquatic species, which live in complex environments and hunt moving prey. Knowledge of whiskers and whisker use can guide us in developing conservation protocols and designing enriched enclosures for captive mammals. We suggest that further comparative studies, embracing a wider variety of mammalian species, are required before one can make large-scale predictions relating to evolution and function of whiskers. More research is needed to develop robust techniques to enhance the welfare and conservation of mammals

Optimizing therapeutics in the management of patients with multiple sclerosis: a review of drug efficacy, dosing, and mechanisms of action

Kavitha Damal, Emily Stoker, John F FoleyRocky Mountain Multiple Sclerosis Research Group, Salt Lake City, UT, USAAbstract: Multiple sclerosis (MS) is a debilitating neurological disorder that affects nearly 2 million adults, mostly in their prime of youth. An environmental trigger, such as a viral infection, is hypothesized to initiate the abnormal behavior of host immune cells: to attack and damage the myelin sheath surrounding the neurons of the central nervous system. While several other pathways and disease triggers are still being investigated, it is nonetheless clear that MS is a heterogeneous disease with multifactorial etiologies that works independently or synergistically to initiate the aberrant immune responses to myelin. Although there are still no definitive markers to diagnose the disease or to cure the disease per se, research on management of MS has improved many fold over the past decade. New disease-modifying therapeutics are poised to decrease immune inflammatory responses and consequently decelerate the progression of MS disease activity, reduce the exacerbations of MS symptoms, and stabilize the physical and mental status of individuals. In this review, we describe the mechanism of action, optimal dosing, drug administration, safety, and efficacy of the disease-modifying therapeutics that are currently approved for MS therapy. We also briefly touch upon the new drugs currently under investigation, and discuss the future of MS therapeutics.Keywords: multiple sclerosis, immunomodulation, interferons, glatiramer acetate, monoclonal antibodies, dimethyl fumarat

Differentiating Enhancing Multiple Sclerosis Lesions, Glioblastoma, and Lymphoma with Dynamic Texture Parameters Analysis (DTPA) - a Feasibility Study.

PURPOSE MR-imaging hallmarks of glioblastoma (GB), cerebral lymphoma (CL), and demyelinating lesions are gadolinium (Gd) uptake due to blood brain barrier disruption. Thus, initial diagnosis may be difficult based on conventional Gd enhanced MRI alone. Here, the added value of a dynamic texture parameter analysis (DTPA) in the differentiation between these three entities is examined. DTPA is an in-house software tool that incorporates the analysis of quantitative texture parameters extracted from dynamic susceptibility contrast enhanced (DSCE) images. METHODS Twelve patients with multiple sclerosis (MS), fifteen patients with GB, and five patients with CL were included. The image analysis method focuses on the DSCE-image time series during bolus passage. Three time intervals were examined: inflow, outflow, and reperfusion time interval. Texture maps were computed. From the DSCE image series mean, difference, standard deviation, and variance texture parameters were calculated and statistically analyzed and compared between the pathologies. RESULTS The texture parameters of the original DSCE-image series for mean, standard deviation and variance showed the most significant differences (p-value between <0.00 and 0.05) between pathologies. Further, the texture parameters related to the standard deviation or variance (both associated with tissue heterogeneity) revealed the strongest discriminations between the pathologies. CONCLUSION We conclude that dynamic perfusion texture parameters as assessed by the DTPA-method allow discriminating MS-, GB- and CL-lesions during the first passage of contrast. DTPA used in combination with classification algorithms have the potential to find the most likely diagnosis given a postulated differential diagnosis. This article is protected by copyright. All rights reserved