The effects of tin (Sn) additions on the growth of spinach plants

An increase in bioavailable tin in the environment could result in bioaccumulation thereof in agricultural crops, and therefore, have adverse health consequences on humans that eat these crops. The aims of the current study were thus to assess the uptake of Sn by spinach plants, and the subsequent effects this will have on the uptake of Na, Zn, K, Ca, and Mg as well as the growth of spinach plants. Spinach plants were grown in sand culture and received tin at concentrations of 0.02, 0.2, 2 and 20 mg/L along with a nutrient solution. The uptake of tin at detectible concentrations only occurred at the highest concentrations (2 and 20 mg/L), and it was mostly retained in the roots of the plants. Tin additions also resulted in no visual toxicity symptoms, and might be beneficial to biomass production. Further field trials are needed to ensure that these experimental results remain true under field conditions.     

Impact of ant predation and heat on carob moth (Lepidoptera: Pyralidae) mortality in California date gardens

Dates, Phoenix dactylifera L., undergo a natural fruit abscission during the summer in California date gardens. Many of the abscised dates become lodged in the date bunch, and we demonstrated that carob moth, Ectomyelois ceratoniae (Zeller), prefer to use these dates as a reproduction host compared with dates that fall to the ground. We also found that abscised fruit shaken onto the ground had significantly fewer live carob moth larvae than fruit that remained in bunches in the tree. Mortality in the dropped fruit was attributed to predation by two native ant species, the fire ant Solenopsis aurea Wheeler, and the California harvester ant, Pogonomyrmex californicus (Buckley), in concert with extreme summer ground temperatures. Dates that fell in the full sunlight rapidly increased in temperature, which resulted in larvae either exiting the fruit (exposing them to ants) or dying in the fruit. Removal of abscised dates from bunches may provide a possible management strategy for carob moths in California date gardens.     

Effect of bunch sanitation on spatial distributions of abscised fruit and phycitine moths (Lepidoptera: Pyralidae) in California date gardens

Phycitine moths are an economic impediment to California date, Phoenix dactylifera L., production. Summer populations build to damaging levels on abscised dates that get trapped in fruit bunches. This study was conducted to determine the relationship between abscised fruit and moth infestation, and to evaluate changes in the spatial distribution of abscised fruit and moth-infested fruit after a bunch-sanitation treatment. Over the 9 wk of this study, there was a 69.9% reduction in the number of moth-infested fruit after a single sanitation treatment. Linear regression analysis showed a significant relationship between abscised fruit and phycitine moth-infested fruit; 42 and 76.6% of the variation in the number of infested fruit was explained by the number of abscised fruit in noncleaned and cleaned plots, respectively. The pattern of reinfestation by moths over the 9 wk posttreatment period was analyzed with spatial analysis with distance indices. Significant spatial associations were found between abscised fruit and moth-infested fruit, supporting the regression analysis. The sanitation treatments caused significant gaps in both abscised fruit and moth-infested fruit. Over time, gap sizes became smaller, indicating a nonrandom pattern of reinfestation that likely was caused by the movement of moths from nontreated areas into treated areas. This study, the first spatial analysis conducted in dates, suggests that in-season bunch sanitation could be effective at reducing summer moth densities if applied on a large regional scale.     

Regulate or tolerate: Thermal strategy of a coral reef flat resident,the epaulette shark,Hemiscyllium ocellatum

Highly variable thermal environments, such as coral reef flats, are challenging for marine ectotherms and are thought to invoke the use of behavioural strategies to avoid extreme temperatures and seek out thermal environments close to their preferred temperatures. Common to coral reef flats, the epaulette shark (Hemiscyllium ocellatum) possesses physiological adaptations to hypoxic and hypercapnic conditions, such as those experienced on reef flats, but little is known regarding the thermal strategies used by these sharks. We investigated whether H. ocellatum uses behavioural thermoregulation (i.e., movement to occupy thermally favourable microhabitats) or tolerates the broad range of temperatures experienced on the reef flat. Using an automated shuttlebox system, we determined the preferred temperature of H. ocellatum under controlled laboratory conditions and then compared this preferred temperature to 6 months of in situ environmental and body temperatures of individual H. ocellatum across the Heron Island reef flat. The preferred temperature of H. ocellatum under controlled conditions was 20.7 ± 1.5°C, but the body temperatures of individual H. ocellatum on the Heron Island reef flat mirrored environmental temperatures regardless of season or month. Despite substantial temporal variation in temperature on the Heron Island reef flat (15–34°C during 2017), there was a lack of spatial variation in temperature across the reef flat between sites or microhabitats. This limited spatial variation in temperature creates a low-quality thermal habitat limiting the ability of H. ocellatum to behaviourally thermoregulate. Behavioural thermoregulation is assumed in many shark species, but it appears that H. ocellatum may utilize other physiological strategies to cope with extreme temperature fluctuations on coral reef flats. While H. ocellatum appears to be able to tolerate acute exposure to temperatures well outside of their preferred temperature, it is unclear how this, and other, species will cope as temperatures continue to rise and approach their critical thermal limits. Understanding how species will respond to continued warming and the strategies they may use will be key to predicting future populations and assemblages.     

Haploinsufficient Bmp4 ocular phenotypes include anterior segment dysgenesis with elevated intraocular pressure

Background  

Glaucoma is a common disease but its molecular etiology is poorly understood. It involves retinal ganglion cell death and optic nerve damage that is often associated with elevated intraocular pressure. Identifying genes that modify glaucoma associated phenotypes is likely to provide insights to mechanisms of glaucoma. We previously reported glaucoma in DBA/2J mice caused by recessive alleles at two loci, isa and ipd, that cause iris stromal atrophy and iris pigment dispersion, respectively. A approach for identifying modifier genes is to study the effects of specific mutations in different mouse strains. When the phenotypic effect of a mutation is modified upon its introduction into a new strain, crosses between the parental strains can be used to identify modifier genes. The purpose of this study was to determine if the effects of the DBA/2J derived isa and ipd loci are modified in strain AKXD-28/Ty.     

Experimentation hyperbare (110 atmospheres) chez un crustace amphipode talitridae

Summary Males and females of the Amphipod crustacean Orchestia gammarella (Talitridae) in period of sexual activity were isolated and compressed in an experimental hyperbaric chamber at pressures between 20 and 110 ATA with oxygen-helium (héliox) mixture (PIo₂ = 300 torr). Stay duration under pressure was 16 days. This stay under pressure did not induce any important disorder like a high pressure nervous syndrome except excitement during compression between 70 and 110 ATA; phenomena of shedding of skin and reproduction did not change; rate of masculinity of the lineage was not modified. Slow decompression did not bring out bends.110 ATA pressure with heliox mixture does not appear to induce obvious deterioration neither in cellular metabolism nor in physiological functions for instance, the intricate functions of reproduction.

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Experimentation hyperbare (110 atmospheres) chez un crustace amphipode talitridae

Résumé Des crustacés Amphipodes Talitridae Orchestia gammarella (Pallas) en période d'activité sexuelle ont été isolés par couple et comprimés à des pressions de l'ordre de 20 à 110 ATA pendant 16 jours dans un caisson expérimental dont l'atmosphère était constituée par un mélange oxygène-hélium (PIo₂ = 300 torr). Ce séjour en pression n'a pas provoqué de signe majeur à rattacher au syndrome nerveux des hautes pressions, si ce n'est une agitation pendant la compression entre 70 et 110 ATA. Les phénomènes de mues et de reproduction n'ont pas été modifiés; le taux de masculinité de la descendance a été comparable à celui d'un groupe témoin. La vitesse de décompression choisie n'a pas entraîné d'accident. La pression de 110 ATA d'un mélange oxygène-hélium ne paraît donc pas entraîner d'altération majeure du méta-bolisme cellulaire et des grandes fonctions physiologiques parmi lesquelles les fonctions complexes de reproduction.

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Laboratoire de Sexualité et Reproduction des Invertébrés. Université Paris VI (Professeur H. Charniaux-Cotton)

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Laboratoire de Physiologie-U.E.R. Sciences Médicales Université de Bretagne Occidentale