Antifeedant Activity of <i>Caesalpinia coriaria</i> Essential Oil Against <i>Incisitermes marginipennis</i> (Latreille)

This study scrutinized the possibility of finding toxicant or deterrent plant metabolites against the dry wood termite Incisitermes marginipennis (Latreille). Plant deterrent agents act as repellents or antifeedants to prevent wood decay and increase its useful life. The potential of the tree Caesalpinia coriaria (Fabaceae) as a biological source of molecules with deterrent effects against the dry wood termite was assessed by a phytochemical fractionation guided by repellence and antifeedant activities. The gas chromatography-mass spectrometry analysis of the leaf essential oil showed geraniol to be one of the major components and its repellent and antifeedant effects were determined. Geraniol had only an antifeedant effect without affecting the body weight or survival of the dry wood termite. Unlike the leaf essential oil, geraniol did not exhibit a repellency effect. An in-silico approach of the activity of acetylcholinesterase in interaction with geraniol resulted in an affinity energy of −7.5 Kcal/mol. Geraniol interacted with the amino acid tyrosine 324 located in the enzyme’s active site while citronellol (negative control) interacted with tryptophan 83 located adjacent to the active site. These deterring terpenes have not been implemented for the preservation and restoration of wood products exposed to the attack of the dry wood termite. However, they are an important natural control alternative.     

Elicitation Improves the Leaf Area,Enzymatic Activities,Antioxidant Activity and Content of Secondary Metabolites in Achillea millefolium L. Grown in the Field

Salicylic acid (SA) is a plant hormone that stimulates the growth and metabolism of plants, also acting as an abiotic elicitor. This study aimed to evaluate the effect of SA on leaf production, leaf area and synthesis of secondary compounds in yarrow plants. The experiments were conducted under field conditions in two consecutive years and f-received SA foliar applications (T1-control; T2-1.0 mmol L⁻¹ applications at 20, 60 and 100 days after planting (DAP) and T3-1.0 mmol L⁻¹ applications at 100 DAP during 3 days). The exogenous application of SA resulted in increases in leaf area (total and specific), number of leaves and leaf mass ratio of yarrow plants, polyphenolic compounds, phenylalanine ammonia-lyase and chalcone synthase enzymes and the antioxidant activity of the plant extract. The HPLC–DAD–MS/MS analysis of phenolic compounds revealed increases in the amounts of quinic acid and rutin. The results of this research lead us to affirm that SA exerted both the hormonal effect on number of leaves and leaf area, and also acted as eliciting substance.

     

Selenomethionine administration decreases the oxidative stress induced by post mortem ischemia in the heart,liver and kidneys of rats

Selenium is an essential element in human and animal metabolism integrated into the catalytic site of glutathione peroxidase (GPX1), an antioxidant enzyme that protects cells from damage caused by reactive oxygen species (ROS). Oxidative stress refers the imbalance between ROS and antioxidant defense systems. It generates alterations of DNA, proteins and lipid peroxidation. The imbalance occurs particularly during ischemia and lack of postmortem perfusion. This mechanism is of relevance in transplant organs, affecting their survival. The aim of this research is to evaluate the effect of seleno-methionine (SeMet) as a protective agent against postmortem ischemia injury in transplant organs. Wistar rats were orally administered with SeMet. After sacrifice, liver, heart and kidney samples were collected at different postmortem intervals (PMIs). SeMet administration produced a significant increase of Se concentration in the liver (65%, p?<?0.001), heart (40%, p?<?0.01) and kidneys (45%, p?<?0.05). Levels of the oxidative stress marker malondialdehyde (MDA) decreased significantly compared to control in the heart (0.21?±?0.04 vs. 0.12?±?0.02 mmol g^?1) and kidneys (0.41?±?0.02 vs. 0.24?±?0.03 mmol g^?1) in a PMI of 1–12 h (p?<?0.01). After SeMet administration for 21 days, a significant increase in GPX1 activity was observed in the liver (80%, p?<?0.001), kidneys (74%, p?<?0.01) and heart (35%, p?<?0.05). SeMet administration to rats significantly decreased the oxidative stress in the heart, liver and kidneys of rats generated by postmortem ischemia.

     

Male competition reverses female preference for male chemical cues

Females must choose among potential mates with different phenotypes in a variety of social contexts. Many male traits are inherent and unchanging, but others are labile to social context. Competition, for example, can cause physiological changes that reflect recent wins and losses that fluctuate throughout time. We may expect females to respond differently to males depending on the outcome of their most recent fight. In Bolitotherus cornutus (forked fungus beetles), males compete for access to females, but copulation requires female cooperation. In this study, we use behavioral trials to determine whether females use chemical cues to differentiate between males and whether the outcome of recent male competition alters female preference. We measured female association time with chemical cues of two size‐matched males both before and after male–male competition. Females in our study preferred to associate with future losers before males interacted, but changed their preference for realized winners following male competitive interactions. Our study provides the first evidence of change in female preference based solely on the outcome of male–male competition.     

Regulation of prostaglandin E2 production by the superoxide radical and nitric oxide in mouse peritoneal macrophages

The purpose of this study was to elucidate the role of NO and O^-₂ on enzymatic components of cyclooxygenase (COX) pathway in peritoneal macrophages. Activation of murine peritoneal macrophages by lipopolysaccharides (LPS) resulted in time-dependent production of nitric oxide (NO) and prostaglandin E₂ (PGE₂). This stimulation was also accompanied by the production of other reactive oxygen species such as superoxide (O^-₂), and by increased expression of COX-2. Our results provide evidence that O^-₂ may be involved in the pathways that result in arachidonate release and PGE₂ formation by COX-2 in murine peritoneal macrophages stimulated by LPS. However, we were not able to demonstrate that NO participates in the regulation of PG production under our experimental conditions.