Asexually propagated Agave tequilana var. azul exhibits variation in genetic markers and defence responses to Fusarium solani.

Agave (Agave tequilana var. azul) is considered a crop with low genetic diversity because it has been propagated vegetatively for centuries for commercial purposes, and consequently, it could be equally susceptible to pests and diseases. However, the present study employs plant material derived from field-grown plants exhibiting phenotypic variability in susceptibility to agave wilt. The offshoots from rhizomes of these plants were reproduced in vitro and classified as potentially resistant or susceptible. Amplified fragment length polymorphism analysis confirmed wide genetic differences among individuals, but these differences were not correlated with the observed phenotypic variability in resistance. Propagated plantlets were inoculated with Fusarium solani in two time-lapse confrontations for 72 h and 30 days. The early biochemical response showed statistically superior levels in the accumulation of shikimic acid, phenolic compounds, and chitinase activity in potentially resistant plantlets. There was an inverse correlation of these early biochemical responses and salicylic acid and the incidence of diseased root cells in isogenic plantlets in the 30-day confrontation with F. solani, suggesting that these activities and accumulation of molecules were primordial in the defence against this pathogen.

Molecular Effects of Silver Nanoparticles on Monogenean Parasites: Lessons from Caenorhabditis elegans.

The mechanisms of action of silver nanoparticles (AgNPs) in monogenean parasites of the genus Cichlidogyrus were investigated through a microarray hybridization approach using genomic information from the nematode Caenorhabditis elegans. The effects of two concentrations of AgNPs were explored, low (6 µg/L Ag) and high (36 µg/L Ag). Microarray analysis revealed that both concentrations of AgNPs activated similar biological processes, although by different mechanisms. Expression profiles included genes involved in detoxification, neurotoxicity, modulation of cell signaling, reproduction, embryonic development, and tegument organization as the main biological processes dysregulated by AgNPs. Two important processes (DNA damage and cell death) were mostly activated in parasites exposed to the lower concentration of AgNPs. To our knowledge, this is the first study providing information on the sub-cellular and molecular effects of exposure to AgNPs in metazoan parasites of fish.

Mercury Levels and Risk Implications Through Fish Consumption on the Sinaloa Coasts (Gulf of California, Northwest Mexico).

Fish consumption is the major source of mercury to humans. Fetuses and children are the most sensitive groups of populations to the effects of mercury. Consequently, fish consumption by pregnant women, children, and women of childbearing age is of concern because of the effects of mercury exposure on human health. To assess mercury exposure in a population in northwest Mexico, the allowed daily consumption of fish (which indicates the maximum daily amount of fish that can be consumed without causing adverse noncarcinogenic effects) was calculated for the general population (GP) and fishing-related population (FRP). The studied groups for both sectors of the population were children A (3-10 years old), children B (11-15 years old), women of childbearing age (16-40 years old), and the rest of the population (men ≥16 years old, and women ≥41 years old). Mercury content in canned and frozen tuna, smoked marlin, tilapia, Pacific sierra, dolphinfish, and bullseye puffer ranged from 0.01 to 0.23 µg/g wet weight; none of the values were above the limit set by Mexico. Regarding mercury concentrations and rates of fish consumption, the GP consumes 1.7-2.7 times the allowed daily consumption, and the FRP consumes 1.6-3.9 that limit. The risk analysis showed the children A and B groups from the GP and adults of FRP to be the highest percentage of the population at risk (approximately 35%). These results highlight the need for adequate strategies that consider mercury exposure as part of public health policies associated with fish consumption in Mexico.