Thermal tolerance in embryos and larvae of the bay scallop Argopecten irradians under simulated power plant entrainment conditions

Thermal tolerance was tested in cleavage stages, trochophores and straight hinge larvae of the bay scallop Argopecten irradians. Experiments were designed to simulate larval entrainment in power plant cooling systems. An 11 (temperature) x 8 (time) matrix was used with temperatures ranging from 20.6 to 43.0 oc and exposure times from 1 min to 6 h. Pooled mortality data from triplicate experiments for each larval stage were subjected to stepwise regression analysis (Yarcsine % mortality on temperature and time). Equations derived from these analyses, comprising first, second and third order terms for temperature and time, were used to generate response surfaces relating mortality to temperature and exposure time. In general. higher mortalities were associated with higher temperatures and with longer time exposure at any one temperature. However, there was some evidence of cold shock in trochophore and straight hinge larvae, with elevated mortalities occurring at temperatures lower than the spawning temperature. There was a trend towards increased thermal tolerance in older larvae, although in general A. irradians showed the greatest sensitivity to thermal shock of the estuarine bivalves so far tested in our laboratory

Population structure of the arkshell clams Noetia ponderosa and Anadara ovalis in the oceanside lagoons and tidal creeks of Virginia and implications for fisheries management

Two species of arkshell (blood) clams, Noetia ponderosa and Anadara ovalis, have · recently been targeted by watermen on the Eastern Shore of Virginia for sale to east coast markets. Until 1991 fishermen caught both species in conjunction with the harvest of oysters and hard clams and considered them of little value. Very little is known about either species, and preliminary data from our pilot study in 1993 indicated that blood clams were being overfished. In September, 1994 we conducted a survey in the oceanside lagoon system along the Eastern Shore and collected data on density, abundance, habitat preference, and mortality rates for both species of blood clams, as well as some ancillary data on the hard clam, Mercenaria mercenaria. The study provides baseline data for establishing management practices and regulations for the bloodclam fishery. Mean clam density for all species in the study area was 1.26 clams per m2 , with the majority of clams occurring in shell/mud substrate. The total estimated abundance in the study area was about 15 .2 million Noetia, 9 .6 million Anadara, and 62.2 millionMercenaria. Of the clams taken in commercial catches on the oceanside of the Eastern Shore, Mercenaria constitutes approximately 84%, Noetia 14.7%, andAnadara 1.4%. Length-frequency data from both the field survey and commercial catches indicate that blood clam stocks are being depleted. We also studied relationships between size and age of blood clams using the acetate peel method. These data, along with growth studies, show that Anadara grows about twice as fast as Noetia and that market-size Noetia (approximately 56 mm in height) may be 8 years old or more. We also present information on mortality rates and morphometric relationships for both species of blood clams, and recommendations for maintaining and enhancing the fishery

Search for Neutron Flux Generation in a Plasma Discharge Electrolytic Cell

Following some recent unexpected hints of neutron production in setups like high-voltage atmospheric discharges and plasma discharges in electrolytic cells, we present a measurement of the neutron flux in a configuration similar to the latter. We use two different types of neutron detectors, poly-allyl-diglicol-carbonate (PADC, aka CR-39) tracers and Indium disks. At 95% C.L. we provide an upper limit of 1.5 neutrons cm^-2 s^-1 for the thermal neutron flux at ~5 cm from the center of the cell. Allowing for a higher energy neutron component the largest allowed flux is 64 neutrons cm^-2 s^-1. This upper limit is two orders of magnitude smaller than what previously claimed in an electrolytic cell plasma discharge experiment. Furthermore the behavior of the CR-39 is discussed to point our possible sources of spurious signals.Comment: 4 pages, 3 figure

Photosynthetic responses to salinity in two obligate halophytes: Sesuvium portulacastrum and Tecticornia indica

Abstract Seedlings of the obligate halophytes Sesuvium portulacastrum L. and Tecticornia indica (Willd.) subsp. indica were grown with 0, 200, or 400 mM NaCl for 13 weeks to investigate whether salt tolerance was related to maintenance of adequate photosynthetic activity and pigment equipment. Both species showed growth optimum at 200 mM NaCl and better tissue hydration under salinity but different photosynthetic response to salinity. CO2 assimilation rate and stomatal conductance of S. portulacastrum were highest at 200 mM NaCl, while in T. indica they decreased with salinity. Pigment content increased under salinity in both species. The de-epoxidation state in S. portulacastrum suggests the need for energy dissipation at 400 mM NaCl, while its salt-induced decline in T. indica, despite the reduced photochemistry, suggests the involvement of adaptive mechanisms other than the xanthophyll cycle

Solar UV-B Radiation Influences Carotenoid Accumulation of Tomato Fruit through Both Ethylene-Dependent and -independent Mechanisms

The effect of UV-B shielding on ethylene production in ripening tomato fruits and the contribution of ethylene and UV-B radiation on carotenoid accumulation and profile during ripening were assessed to get more insight about the interplay between these two regulatory factors. To this aim, rin and nor tomato mutants, unable to produce ripening ethylene, and cv Ailsa Craig were cultivated under control or UV-B depleted conditions until full fruit ripening. The significantly decreased ethylene evolution following UV-B depletion, evident only in Ailsa Craig, suggested the requirement of functional rin and nor genes for UVB-mediated ethylene production. Carotenoid content and profile were found to be controlled by both ethylene and UV-B radiation. This latter influenced carotenoid metabolism either in an ethylene-dependent or -independent way, as indicated by UVB-induced changes also in nor and rin carotenoid content and confirmed by correlation plots between ethylene evolution and carotenoid accumulation performed separately for control and UV-B shielded fruits. In conclusion, natural UV-B radiation influences carotenoid metabolism in a rather complex way, involving ethylene-dependent and -independent mechanisms, which seem to act in an antagonistic way

Development of an ELISA test for Salmonella serological monitoring in Brazil

EMBRAPA/CNPSA developed an ELISA test based on LPS antigens from Salmonella Typhimurium. After the optimal dilution determination of the test components, four sera were chosen as controls. The interplate variation was controlled by a coefficient correlation between standard and daily curves of control sera and the coefficient variation of sample sera triplicates. The cut-off was determined by a dispersion analysis in a nursery piglet population proved to be salmonellae negative. The test performance was evaluated in experimentally and naturally S. Typhimurium infected pigs and in animals vaccinated with other Salmonella serovars. The seroconversion was observed after two weeks post inoculation in experimentally infected and vaccinated animals. In naturally infected animals, which were sampled twice during the finishing period, at the first sampling 75 % of pigs were eliminating salmonellae in feces and 25 % were positive in the ELISA. At the second sampling 76.9 % became serologically positive. These results suggest that the developed test can be used for Salmonella Typhimurium monitoring programs in swine

Comparison of voluntary food intake and palatability of commercial weight loss diets in healthy dogs and cats

Background Obesity in dogs and cats is usually managed by dietary energy restriction using a purpose-formulated weight loss diet, but signs of hunger and begging commonly occur causing poor owner compliance. Altering diet characteristics so as to reduce voluntary food intake (VFI) can improve the likelihood of success, although this should not be at the expense of palatability. The aim of the current study was to compare the VFI and palatibility of novel commercially available canine and feline weight loss diets. Methods The relative performance of two canine (C1 and C2) and two feline (F1 and F2) diets was assessed in groups of healthy adult dogs and cats, respectively. Diets varied in energy, protein, fibre, and fat content. To assess canine VFI, 12 (study 1) and 10 (study 2) dogs were offered food in 4 meals, for 15 min on each occasion, with hourly intervals between the meals. For feline VFI, 12 cats were offered food ad libitum for a period of 18 h per day over 5 consecutive days. The palatability studies used separate panels of 37 dogs and 30 cats, with the two diets being served, side-by-side, in identical bowls. Results In dogs, VFI was significantly less for diet C1 than diet C2 when assessed on energy intake (study 1, 42% less, P = 0.032; study 2, 28% less, P = 0.019), but there was no difference in gram weight intake (study 1: P = 0.964; study 2: P = 0.255). In cats, VFI was 17% less for diet F1 than diet F2 when assessed by energy intake (P < 0.001), but there was again no difference in gram weight (P = 0.207). There was no difference in palatability between the two canine diets (P = 0.490), whilst the panel of cats diet preferred F1 to F2 (P < 0.001). Conclusion Foods with different characteristics can decrease VFI without affecting palatability in both dogs and cats. The effects seen could be due to decreased energy content, decreased fat content, increased fibre content, different fibre source, and increased protein content. Further studies are now needed to determine whether similar findings occur in obese dogs and cats on controlled weight loss programmes

A large sample study of spin relaxation and magnetometric sensitivity of paraffin-coated Cs vapor cells

We have manufactured more than 250 nominally identical paraffin-coated Cs vapor cells (30 mm diameter bulbs) for multi-channel atomic magnetometer applications. We describe our dedicated cell characterization apparatus. For each cell we have determined the intrinsic longitudinal, \sGamma{01}, and transverse, \sGamma{02}, relaxation rates. Our best cell shows \sGamma{01}/2\pi\approx 0.5 Hz, and \sGamma{02}/2\pi\approx 2 Hz. We find a strong correlation of both relaxation rates which we explain in terms of reservoir and spin exchange relaxation. For each cell we have determined the optimal combination of rf and laser powers which yield the highest sensitivity to magnetic field changes. Out of all produced cells, 90% are found to have magnetometric sensitivities in the range of 9 to 30 fTHz. Noise analysis shows that the magnetometers operated with such cells have a sensitivity close to the fundamental photon shot noise limit