Validation of a method for measuring sperm quality and quantity in reproductive toxicity tests with pair-breeding male fathead minnows (Pimephales promelas)

This article originally appeared in the ILAR e-Journal. It is reprinted with permission from the ILAR Journal, Institute for Laboratory Animal Research, National Research Council, Washington DC (www.nationalacademies.org/ilar).The fathead minnow (Pimephales promelas) is an OECD-proposed test species routinely used in reproductive toxicity trials with suspected endocrine-disrupting compounds (EDCs). The basic fecundity, endocrinology, and histopathology of reproductively active male and female fathead minnows has been well characterized, but there are few studies of the utility of male sperm concentration and motility as endpoints for use in reproductive trials. The purpose of this study was to (1) characterize the baseline sperm concentration and motility of pair-breeding male fathead minnows over their spawning cycle and (2) determine whether a repeated and nondestructive sperm sampling protocol would influence the baseline fecundity of the fish. Pair-breeding male fathead minnows that underwent sampling for milt three times a week for 4 weeks exhibited no significant changes in milt volume, sperm concentration, or motility parameters up to 6 days after each spawning event. The repeated sperm sampling procedure did, however, cause a significant lowering of spawning frequencies, although this decline did not correlate with effects on fecundity as there were no significant changes in the mean total numbers of eggs laid, fertilization, and hatching successes. This study confirmed the presence of a stable background of sperm concentration and motility parameters of pair-breeding male fathead minnows under reference conditions. The absence of any inherent “cycling” in the magnitude of these parameters over the spawning period suggests that sperm concentration and motility could be useful measures of male reproductive toxicity at the termination of tests in which pair-breeding males are at varying days post spawn.The research described was funded by the EU project Comparative Research on Endocrine Disrupters (COMPRENDO) Institute of Zoology Regents Park, London, contract No. EVK1-CT-2002-00129E

Landscape influences on fisher success: Adaptation strategies in closed and open access fisheries in southern Chile

Determinants of fisher success in southern Chile's loco (Concholepas concholepas) fishery are examined by comparing fisher success in exclusive access territories that vary in relationship to tree-plantation development, which can affect shellfish quality. The relative importance of fishers' experience and capture technology (traditional measures of fisher success) are evaluated against environmental and geospatial characteristics. While knowledge and technology explained variation in catches, this did not translate into higher prices or profit. Fishers succeeded (gained higher prices for locos and had higher monthly incomes from their management areas) when they harvested shellfish from closed (exclusive) nearshore management areas where the environmental condition produced high quality locos regardless of their fishing experience, technology, and the geospatial features of management areas. Experienced fishers who worked in management areas near tree plantations that fail to produce resources of sufficient quality shifted to offshore fisheries where their experience counted. Offshore fishers working in the congrio (Genypterus chilensis) fishery likely exposed themselves to more risk and benefited from their experience and available technology; environmental condition and geospatial factors played little role in their success (price). Closed management areas provided resources to harvest, but may reduce a fisher's ability to adapt to environmental change because success depends on environmental factors outside of a fisher's control. Fishers were not financially rewarded for their experience or their technology in the loco fishery

Translational Studies in Elderly Patients with Acute Myeloid Leukemia

The production of blood cells (hematopoiesis) takes place in the bone marrow. Acute myeloid leukemia (AML) is a clonal disease, which is characterized by an increase in the number of myeloid cells in the bone marrow and an arrest in their maturation. This frequently results in a severe suppression of normal hematopoiesis (granulocytopenia, anemia and/or thrombocytopenia).1,2 AML is a heterogeneous disease, characterized by a diversity of morphologic, cytogenetic and immunophenotypic features. Until recently, the morphologic classification was according to the French-American-British group,3-5 which distinguishes AML into nine distinct subtypes (FAB M0-M7, M4eo) that differ with respect to the particular myeloid lineage involved and the degree of leukemic-cell differentiation. This distinction is based on the morphologic appearance of the blasts and their reactivity with histochemical stains. In addition, immunologic methods have been incorporated into the diagnostic criteria for some FABgroups, e.g. M0 and M7.6,7 Cytogenetic abnormalities of the chromosomes in the leukemic blasts have also been shown to be associated with specific FAB subtypes, e.g. t(15;17) with acute promyelocytic leukemia (APL; AML M3).8 Recently, the World Health Organization (WHO) has proposed a new classification for myeloid neoplasms.9 In this classification, genetic features (cytogenetic and molecular genetic) and clinical features have been integrated with morphology and immunophenotype to define distinct disease entities. Within the category of AML, four main groups have been recognized: 1. AML with recurrent cytogenetic translocations; 2. AML with myelodysplasia-related features; 3. therapy-related AML and MDS; and 4. AML not otherwise specified

Mineralisation of soft and hard tissues and the stability of biofluids

Evidence is provided from studies on natural and artificial biofluids that the sequestration of amorphous calcium phosphate by peptides or proteins to form nanocluster complexes is of general importance in the control of physiological calcification. A naturally occurring mixture of osteopontin peptides was shown, by light and neutron scattering, to form calcium phosphate nanoclusters with a core–shell structure. In blood serum and stimulated saliva, an invariant calcium phosphate ion activity product was found which corresponds closely in form and magnitude to the ion activity product observed in solutions of these osteopontin nanoclusters. This suggests that types of nanocluster complexes are present in these biofluids as well as in milk. Precipitation of amorphous calcium phosphate from artificial blood serum, urine and saliva was determined as a function of pH and the concentration of osteopontin or casein phosphopeptides. The position of the boundary between stability and precipitation was found to agree quantitatively with the theory of nanocluster formation. Artificial biofluids were prepared that closely matched their natural counterparts in calcium and phosphate concentrations, pH, saturation, ionic strength and osmolality. Such fluids, stabilised by a low concentration of sequestering phosphopeptides, were found to be highly stable and may have a number of beneficial applications in medicine

Study of odd-mass N=82 isotones with realistic effective interactions

The microscopic quasiparticle-phonon model, MQPM, is used to study the energy spectra of the odd $Z=53 - 63$, N=82 isotones. The results are compared with experimental data, with the extreme quasiparticle-phonon limit and with the results of an unrestricted $2s1d0g_{7/2}0h_{11/2}$ shell model (SM) calculation. The interaction used in these calculations is a realistic two-body G-matrix interaction derived from modern meson-exchange potential models for the nucleon-nucleon interaction. For the shell model all the two-body matrix elements are renormalized by the $\hat{Q}$-box method whereas for the MQPM the effective interaction is defined by the G-matrix.Comment: Elsevier latex style espart, 26 pages, submitted to Nuclear Physics

Plasma convection at high latitudes using the EISCAT VHF and ESR incoherent scatter radars

International audienceThe recent availability of substantial data sets taken by the EISCAT Svalbard Radar allows several important tests to be made on the determination of convection patterns from incoherent scatter radar results. During one 30-h period, the Svalbard Radar made 15 min scans combining local field aligned observations with two, low elevation positions selected to intersect the two beams of the Common Programme Four experiment being simultaneously conducted by the EISCAT VHF radar at Tromsø. The common volume results from the two radars are compared. The plasma convection velocities determined independently by the two radars are shown to agree very closely and the combined three-dimensional velocity data used to test the common assumption of negligible field-aligned flow in this regime.Key words: Ionosphere (auroral ionosphere; polar ionosphere) - Magnetospheric physics (plasma convection

Subsidence of the West Siberian Basin: Effects of a mantle plume impact

Comparison of modeling results with observed subsidence patterns from the West Siberian Basin provides new insight into the origin of the Siberian Traps, and constrains the temperature, size, and depth of an impacting mantle plume head during and after the eruption of the Siberian Traps at the Permian-Triassic boundary (250 Ma). We compare subsidence patterns from one-dimensional conductive heat flow models to observed subsidence from backstripping studies of wells in the basin. This results in a best-fit scenario with a 50-km-thick initial plume head with a temperature of 1500 °C situated 50 km below the surface, and an initial regional crustal thickness of 34 km, in agreement with published values. Backstripping and modeling results agree very well, including a 60–90 m.y. delay between the rifting phase and the first regional sedimentation. Regional subsidence patterns indicate that the plume head was present across a minimum area of ∼2.5 × 106 km2. These results re-emphasize the viability of a mantle plume origin for the Siberian Traps, provide important constraints on the dynamics of mantle plume heads, and suggest a thermal control for the subsidence of the West Siberian Basin

Scale construction and evaluation in practice:A review of factor analysis versus item response theory applications

In scale construction and evaluation, factor analysis (FA) and item response theory (IRT) are two methods frequently used to determine whether a set of items reliably measures a latent variable. In a review of 41 published studies we examined which methodology – FA or IRT – was used, and what researchers’ motivations were for applying either method. Characteristics of the studies were compared to gain more insight into the practice of scale analysis. Findings indicate that FA is applied far more often than IRT. Many times it is unclear whether the data justify the chosen method because model assumptions are neglected. We recommended that researchers (a) use substantive knowledge about the items to their advantage by more frequently employing confirmatory techniques, as well as adding item content and interpretability of factors to the criteria in model evaluation; and (b) investigate model assumptions and report corresponding findings. To this end, we recommend more collaboration between substantive researchers and statisticians/psychometricians