The different dissipation behavior of chiral pesticide paclobutrazol in the brine during Chinese cabbage pickling process

Paclobutrazol (PBZ) is a kind of chiral pesticide, which is a plant growth regulator and has fungicidal activity. Because of the steric‐hindrance effect, there are two enantiomers (2S, 3S; 2R, 3R) in the production. This research studied on the dissipation behavior of chiral pesticide PBZ in the brine during the Chinese cabbage pickled process by phase column‐high performance liquid chromatography (HPLC). The result demonstrated the PBZ enantiomers had the different dissipation in the brine. The study on the behavior of chiral pesticide PBZ in food may provide more sufficient data and information for understanding the potential risk in food and evaluating the environmental pollution at the enantiomer level.     

Reduced habitat quality increases intrinsic but not ecological costs of reproduction

Although the costs of reproduction are predicted to vary with the quality of the breeding habitat thereby affecting population dynamics and life‐history trade‐offs, empirical evidence for this pattern remains sparse and equivocal. Costs of reproduction can operate through immediate ecological mechanisms or through delayed intrinsic mechanisms. Ignoring these separate pathways might hinder the identification of costs and the understanding of their consequences. We experimentally investigated the survival costs of reproduction for adult little owls (Athene noctua) within a gradient of habitat quality. We supplemented food to nestlings, thereby relieving the parents’ effort for brood provisioning. We used radio‐tracking and Bayesian multistate modeling based on marked recapture and dead recovery to estimate survival rates of adult little owls across the year as a function of food supplementation and habitat characteristics. Food supplementation to nestlings during the breeding season increased parental survival not only during the breeding season but also during the rest of the year. Thus, the low survival of parents of unfed broods likely represents both, strong ecological and strong intrinsic costs of reproduction. However, while immediate ecological costs occurred also in high‐quality habitats, intrinsic costs carrying over to the post‐breeding period occurred only in low‐quality habitats. Our results suggest that immediate costs resulting from ecological mechanisms such as predation, are high also in territories of high habitat quality. Long‐term costs resulting from intrinsic trade‐offs, however, are only paid in low‐quality habitats. Consequently, differential effects of habitat quality on immediate ecological and delayed intrinsic mechanisms can mask the increase of costs of reproduction in low‐quality breeding habitats. Intrinsic costs may represent an underrated mechanism of habitat quality affecting adult survival rate thereby considerably accelerating population decline in degrading habitats. This study therefore highlights the need for a long‐term perspective to fully assess the costs of reproduction and the role of habitat quality in modifying these costs.     

Evolutionarily stable stealing: game theory applied to kleptoparasitism

We present an individual-based model of a group of foraginganimals. Individuals can obtain food either by discovering itthemselves or by stealing it from others (kleptoparasitism).Given that challenging another individual for a discovered fooditem costs time (which could otherwise be spent searching foran undiscovered item), attempting to steal from another maynot always be efficient We show that there is generally a uniquestrategy that maximizes uptake rate—always or never challengingothers. For any combination of parameter values, we can identifywhich strategy is appropraite. As a corollary to this, we predictthat small changes in ecolgical conditions can, under some circumstances,cause a dramatic change in the aggressive behavior of individuals.Further, we investigate situations where searching for undiscoveredfood and searching for potential opportunities for stealingare mutually exclusive activities (i.e., success at one canonly be improved at the expense of the other). Using game theory,we are able to find the evolutionarily stable strategy for investmentin these two activities in terms of the ecological parametersof the model.     

Accelerated growth rates in late‐hatched Rhinoceros Auklet Cerorhinca monocerata chicks depend on food conditions and growth stage: an experimental approach

In some bird species, the survival of chicks hatching later in the season is lower than those hatched earlier due to increased risk of predation and a seasonal decline in feeding conditions. To reduce these risks, it might be advantageous for late‐hatched chicks to grow faster and hence fledge at younger age. In this experimental study, the growth rates of early‐ and late‐hatched Rhinoceros Auklet Cerorhinca monocerata chicks were compared under average and poor food supplies in captivity. Controlling for potentially confounding effects of chick mass at 10 days old, chick age and nest‐chamber temperature, late‐hatched chicks had higher wing growth rate than early‐hatched chicks before attaining the minimum wing length required for fledgling under both average and poor food supplies. After attaining the minimum wing length, however, late‐hatched chicks had a lower fledging mass, indicating a potential cost that could diminish the early advantage of fast wing growth.     

Neurobehavioral Dysfunction as a Possible Sentinel of Methylmercury Exposure

The main concern regarding methylmercury neurotoxicity relates to adverse effects on the brain during development. Many environmental chemicals may act as developmental neurotoxicants, but solid documentation from epidemiological studies exists only on methylmercury, lead, and polychlorinated biphenyls (PCBs). Neurobehavioral tests may reveal subtle dysfunctions, but the tests chosen must be valid and appropriate for the setting. In a prospective study in the Faroe Islands, the main neuropsychological functions affected by prenatal methylmercury exposure were attention, language and memory. Deficits in visuospatial function were mainly related to postnatal exposures. These associations were stable after adjustment for confounders and exclusion of the children with the highest exposures to methylmercury and PCBs. Tests with good psychometric properties were more likely to show an association with mercury exposure. Greater sensitivity was also seen with tests administered by specialized academic staff rather than a trained technician. Despite highly significant effects on nervous system function, the deficits were subtle, and mercury exposure explained only a small part of the variation. Available evidence suggests that neurotoxicity may have severe implications on public health, but current methods are not amenable to application as sentinels of adverse health effects in environmental health surveillance.     

Lipids of the tropical seagrass Thallassia hemprichii

The component sterols, alcohols, hydrocarbons, monocarboxylic, α,ω-dicarboxylic and α- and ω-hydroxy acids from the leaves and roots of the tropical seagrass Thallassia hemprichii are reported. The leaves contained significant concentrations of cholest-5-en-3β-ol, a sterol not normally detected in either higher plants or seagrasses. The lower abundance of polyunsaturated fatty acids found in both the leaves and roots compared to other seagrass species may be a result of the warmer waters from which this species was collected. Solvent-extractable, long-chain (> C₂₂)α,ω-diacids, α- and ω-hydroxy and monocarboxylic acids were also isolated from the leaves. The distribution pattern of these lipids should enable these components along with other distinctive components to be used as chemical markers for this seagrass.     

Changes in food intake,body weight,gonads and plasma concentrations of thyroxine,luteinizing hormone and testosterone in captive male buntings exposed to natural daylengths at 29° N

We have investigated the seasonal changes in food intake, body weight, gonadal volume and plasma concentrations of thyroxine, luteinizing hormone and testosterone in male blackheaded bunting (Emberiza melanocephala) in captivity under natural daylengths at 29° N. The cycles in food intake, body weight and testis size in buntings appeared to be phase related. While the changes in body weight and testicular size were parallel to each other and correspond to the increasing daylengths of spring and early summer, cycle in food intake was almost antiphase to the cycles in body weight and testicular growth and development. Furthermore, buntings showed a distinct seasonal cycle in plasma concentrations of thyroxine, luteinizing hormone and testosterone. It is suggested that these seasonal cycles in buntings are endogenously programmed and their entrainment to the environmental photoperiod ensures the occurrence of different physiological functions at temporally fixed time of the year.     

Evaluation of a new chromogenic agar for the detection of Listeria in food

AIM: Rapid identification of Listeria in food is important in protecting consumers from infection. The development of chromogenic media such as agar Listeria according to Ottaviani and Agosti (ALOA) has allowed more rapid detection of Listeria monocytogenes, with presumptive identification of this pathogenic species after only 24 h of incubation. The aim of this study was to evaluate Oxoid chromogenic Listeria agar (OCLA) in comparison with ALOA and a traditional, nonchromogenic medium, Oxford agar. METHODS AND RESULTS: Media were compared using pure cultures, spiked food samples and naturally contaminated samples. Whilst development of typical colony morphology took 48 h on Oxford agar, Listeria spp. were frequently detected after 24 h of incubation on OCLA and ALOA. There was no significant difference in recovery between the two chromogenic media. CONCLUSIONS: Results indicate that OCLA gives equivalent recovery of Listeria spp. compared with ALOA. Whilst L. monocytogenes was frequently detected after 24 h of incubation, a 48-h incubation time was necessary to ensure detection of both L. monocytogenes and other Listeria spp. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has shown that a commercially available chromogenic medium other than ALOA is appropriate for use in the international standard method. The commercial availability of more than one medium will facilitate the more widespread use of the method, thus increasing confidence in the ability to detect L. monocytogenes in food in the presence of other Listeria spp.     

Characterization of extended-spectrum beta-lactamase-producing Enterobacterales from organic and conventional chicken meats

This study was conducted to isolate and identify extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales in conventional and organic chicken meats, which were sold in Turkey. A total of 200 raw chicken meat sample (100 conventional and 100 organic) were used as material. Classic culture technique based on chromogenic method was used for the isolation of bacteria, and the identification was performed with VITEK MS. Phenotypic ESBL production was detected by combined disc diffusion method. Gene regions responsible for ESBL production were determined by PCR. MIC values of isolates were detected by VITEK 2. Phenotypic ESBL-producing Enterobacterales were detected in 46% of conventional chicken meats and in 22% of organic chicken meats. Of the 115 isolates obtained, 97 (84%) were Escherichia coli, 12 (10%) were Klebsiella pneumoniae, four (3·48%) were Serratia fonticola, one (0·87%) was Rahnella aquatilis, and one (0·87%) was Serratia liquefaciens. PCR analysis revealed that 109 of 115 isolates (94·78%) contained at least one of the bla_CTX-M, bla_TEM, and bla_SHV genes. Of the 115 ESBL-producing isolates, 103 (89·57%) were found resistant to at least one antibiotic except for the β-lactam group. The contamination level of ESBL-producing Enterobacterales was higher in conventional chicken meats (P < 0·001).