Le ionophore A23187

The acrosomic status of spermatozoa prepared for IVF has been evaluated by means of immunofluorescence test from Fenichel and Hsi using calcium A 23187 ionophore as inductor of acrosome reaction (AR). The spontaneous AR remains slight, even after 6 hour-incubation in Menezo B2 (6,8+2,7%). The response to ionophore, moderate before (11,2+9%), frankly increases after a 6h-capacitation (28,9+8,3%) in a group of 25 IVF couples (tubal indication, normal semen, positive fertilization). Nevertheless, it remains slight or null in 4 cases of unexplained repeated failure of fertilization. The response to ionophore A 23187 allows to explore the kinetics of capacitation of spermatozoa and their ability to perform AR. Its significance in terms of fecondance remains to be precised.     

Measured voluntary avoidance behaviour during the 2009 A/H1N1 epidemic

Managing infectious disease is among the foremost challenges for public health policy. Interpersonal contacts play a critical role in infectious disease transmission, and recent advances in epidemiological theory suggest a central role for adaptive human behaviour with respect to changing contact patterns. However, theoretical studies cannot answer the following question: are individual responses to disease of sufficient magnitude to shape epidemiological dynamics and infectious disease risk? We provide empirical evidence that Americans voluntarily reduced their time spent in public places during the 2009 A/H1N1 swine flu, and that these behavioural shifts were of a magnitude capable of reducing the total number of cases. We simulate 10 years of epidemics (2003–2012) based on mixing patterns derived from individual time-use data to show that the mixing patterns in 2009 yield the lowest number of total infections relative to if the epidemic had occurred in any of the other nine years. The World Health Organization and other public health bodies have emphasized an important role for ‘distancing’ or non-pharmaceutical interventions. Our empirical results suggest that neglect for voluntary avoidance behaviour in epidemic models may overestimate the public health benefits of public social distancing policies.     

Fish and fisheries in hot water: What is happening and how do we adapt?

Rapid climate changes are currently driving substantial reorganizations of marine ecosystems around the world. A key question is how these changes will alter the provision of ecosystem services from the ocean, particularly from fisheries. To answer this question, we need to understand not only the ecological dynamics of marine systems, but also human adaptation and feedbacks between humans and the rest of the natural world. In this review, we outline what we have learned from research primarily in continental shelf ecosystems and fishing communities of North America. Key findings are that marine animals are highly sensitive to warming and are responding quickly to changes in water temperature, and that such changes are often happening faster than similar processes on land. Changes in species distributions and productivity are having substantial impacts on fisheries, including through changing catch compositions and longer distances traveled for fishing trips. Conflicts over access to fisheries have also emerged as species distributions are no longer aligned with regulations or catch allocations. These changes in the coupled natural-human system have reduced the value of ecosystem services from some fisheries and risk doing so even more in the future. Going forward, substantial opportunities for more effective fisheries management and operations, marine conservation, and marine spatial planning are likely possible through greater consideration of climate information over time-scales from years to decades.     

Analysis of Glycerol-3H Transport in the Frog Oocyte by Extractive and Radioautographic Techniques

The efflux of glycerol-³H from mature R. pipiens oocytes was studied by extractive analysis and by quantitative radioautography using techniques suitable for diffusible solutes. Extractive analysis was used to determine the total cellular concentration of tracer, and radioautography, regional intracellular concentrations, at equilibrium and as a function of efflux time, t_E. The efflux was resolvable into four kinetic fractions: cytoplasmic fast and slow fractions, and nuclear fast and slow fractions. The fast fractions represent freely diffusible glycerol in the two compartments; the solvent space accessible to glycerol is unity in the nucleus (germinal vesicle), but only 0.73 in the cytoplasm. The efflux of both fast fractions from the cell is determined by the permeability of the cortical membrane, with neither the nuclear membrane nor diffusion in the cytoplasm detectably slowing the flux. The permeability at 13.6°C is 2.2 x 10^-5 cm/sec. The slow fractions leave the cell at about one-tenth the rate of the fast; the interpretation is that these fractions represent glycerol bound to impermeant cellular constituents. The size of these constituents is below the radioautographic resolution; in the cytoplasm, they appear not to be the yolk platelets. The extent of binding is about fourfold greater, per milliliter of compartment water, in the cytoplasm than in the germinal vesicle.     

Difficulty in clinical identification of neonatal seizures: an EEG monitor study

Seventeen newborns were monitored for 24 hours using a three-channel ambulatory EEG (A/EEG). All newborns were thought to be having subtle seizures by the nursery staff. Fifteen of the 17 newborns were recorded as having 1-30 clinical seizures during the time of monitoring. Only one newborn had clinically identified seizures associated with A/EEG discharges. The seizures were characterized by eye rolling. Fifty-two episodes (thought to be seizures) of lip smacking, bicycling, jerking, fisting, staring, stiffening, or any combination of the above occurred in eight newborns without an associated discharge on A/EEG. However, two of the eight had seizure discharges at other times, not associated with any clinical manifestation. Seventy-four apnea spells, thought to be possible seizures, occurred in seven newborns. None was associated with discharges on A/EEG, but one of these newborns had 50 A/EEG discharges unrelated to apnea or other clinical manifestations.     

Preparing for a changing future in recreational fisheries: 100 research questions for global consideration emerging from a horizon scan

Reviews in Fish Biology and Fisheries - Recreational fisheries hold immense ecological, social, and economic value. The management of these fisheries is increasingly important as we move forward in...     

Characterization of a cDNA clone coding for human testis membrane cofactor protein (MCP,CD46)

Membrane cofactor protein (MCP) is a complement regulatory protein that acts as a cofactor for the cleavage of C3b and C4b by the serine protease factor I. We have previously reported the characterization of a functional MCP molecule on the acrosomal membrane. This protein migrated as a single band with a molecular weight of 40,000 Da, which is 10,000–20,000 Da smaller than the known MCP molecules, and is devoid of N-and O-linked sugars. We have proposed that the difference in molecular weight resulted from the lack of sugars. To investigate if this is due to the absence of glycosylation sites, we have characterized a cDNA clone from a human testis cDNA library. This cDNA corresponds to a peculiar MCP form previously described, which is characterized by the presence of the serine/threonine/proline-rich exon C (STP^C) and the cytoplasmic tail known as CYT², and we conclude that the absence of mature oligosaccharide of the sperm MCP cannot be totally attributed to a defect of N- and O-glycosylation sequences but rather reflects an alteration of the mechanisms of glycosylation in spermatozoa. The presence of functional MCP on the acrosomal membrane, as well as the other complement regulatory protein, decay-accelerating factor, strongly suggests that these proteins may act concomitantly to protect the acrosome-reacted spermatozoa from the attack of the complement present in the female genital tract. © 1993 Wiley-Liss, Inc.