15 research outputs found
Unexpected species diversity in electric eels with a description of the strongest living bioelectricity generator
Is there only one electric eel species? For two and a half centuries since its description by Linnaeus, Electrophorus electricus has captivated humankind by its capacity to generate strong electric discharges. Despite the importance of Electrophorus in multiple fields of science, the possibility of additional species-level diversity in the genus, which could also reveal a hidden variety of substances and bioelectrogenic functions, has hitherto not been explored. Here, based on overwhelming patterns of genetic, morphological, and ecological data, we reject the hypothesis of a single species broadly distributed throughout Greater Amazonia. Our analyses readily identify three major lineages that diverged during the Miocene and Pliocene—two of which warrant recognition as new species. For one of the new species, we recorded a discharge of 860 V, well above 650 V previously cited for Electrophorus, making it the strongest living bioelectricity generator. © 2019, The Author(s)
Cranial morphology of the Stellate Sturgeon, Acipenser stellatus Pallas 1771 (Acipenseriformes, Acipenseridae), with notes on the skulls of other sturgeons
Extant members of Acipenseridae are generally classified in four genera: Scaphirhynchus, Pseudoscaphirhynchus, Huso and “Acipenser,” which is widely recognized to be paraphyletic. Advances have been made in understanding the systematic relationships among sturgeons based on both morphological and molecular data. Analysis of mitochondrial DNA data suggested that Pseudoscaphirhynchus should be regarded as nested within “Acipenser,” specifically as sister group to the Stellate Sturgeon, A. stellatus. Recent morphological analyses also recovered this relationship, supported by a number of osteological synapomorphies, although these results were based on few and relatively small individuals. Here we describe the anatomy of the skull of A. stellatus based on newly prepared specimens of adult individuals, as well as examination of a large number of preserved individuals representing a broad range of ontogenetic stages. We present new anatomical data from all regions of the skull (dermatocranium, neurocranium, viscerocranium) and offer interpretations of these and other characters. In particular, we describe the allometry in the snout of A. stellatus, which undergoes substantial elongation relative to other sturgeons. Aspects of the skull of A. stellatus are compared to other members of the family, specifically the course of the occipital sensory canal and the morphology and distribution of cranial spines
Can Preserved Museum Specimens Be Used to Reconstruct Fish Mercury Burden and Sources through Time?
To
evaluate the utility of preserved fish for reconstructing historical
and spatial patterns of mercury (Hg) exposure, we experimentally tested
the stability of Hg concentrations and Hg stable isotope ratios under
standard museum practices of specimen preservation. We found that
loss of unidentified constituents during preservation increased Hg
concentrations in fish muscle. Low-Hg fish reared in the laboratory
were susceptible to exogenous contamination with inorganic mercury
(iHg) when preservative fluids were intentionally spiked or iHg leached
passively from contaminated wild fish in the same container. This
contamination impacted Hg isotope values of total Hg, but the conservative
nature of methylmercury allows us to quantitatively correct for iHg
contamination. Our findings validate the potential to use fish from
the world’s museums to generate spatiotemporal baselines for
the Minamata Convention on Mercury, but we recommend a set of precautions
to maximize inference strength. Selecting the largest specimens of
a target species helps dilute any iHg contamination. Specimens should
be drawn from lots that were not comingled with fish from other collections
to minimize risk of iHg transfer among fish with different contamination
histories. Finally, focusing on low-lipid species will enhance the
comparability of Hg concentrations between historical and contemporary
collections
Genetic Diversity among Hatchery Stocks and Established Populations of Rainbow Trout in Missouri
Violent behaviour and post-traumatic stress disorder in US Iraq and Afghanistan veterans
Phase II Study of Belagenpumatucel-L, a Transforming Growth Factor Beta-2 Antisense Gene-Modified Allogeneic Tumor Cell Vaccine in Non–Small-Cell Lung Cancer
Developing Tools to Encourage Private Forest Landowners to Participate in Early Successional Forest Habitat Management
Innovative research methods in health social sciences : an introduction
Innovative, or creative research, methods have become increasingly popular in the last few decades. In this chapter, I will include several salient issues on which chapters in the section on “Innovative Research Methods in Health Social Sciences” can be situated. First, I discuss some ideas about innovative and creative methods. This is followed with the notion of those who practice innovative methods: the innovative researcher. I will then bring readers through a number of innovative and creative methods that researchers have adopted in their research. These include the theoretical lens, arts-based and visual research methods, the body and embodiment research, digital methods, and textual (plus visual) methods of inquiry. As an innovative researcher, our choice of innovative methods primarily depends on the questions we pose; the people who are involved; our moral, ethical, and methodological competence as researchers; and the sociocultural environment of the research. As we are living in the world that continue to change, it is likely that health and social science researchers will continue to experiment with their creative methods in order to ensure the success of their research. I anticipate that in the future, we will see even more creative methods that researchers will bring forth