Optimal foraging theory predicts that predators choose the most energetically profitable prey. At the northern limit of its distribution the puma Puma concolor tends to prey on large mammals, whereas at the southern limit its prey comprises medium‐sized and small mammals. We analysed the puma's food habits in Central Mexico, and concluded that the nine‐banded armadillo Dasypus novemcinctus is the main prey, followed by the white‐nosed coati Nasua narica and white‐tailed deer Odocoileus virginianus. The puma's standardised niche breadth (B') was 0.21 and was in accordance with the expected in the exponential model. We compared this with niche breadths recorded in other studies carried out in the Americas. After a forest fire, puma changed their feeding habits and began to hunt prey > 6.1 kg more frequently. Food preferences of puma in Central Mexico resemble those recorded for puma in South America rather than the preferences recorded for puma in other North American populations.

Sexually dimorphic plants provide an excellent opportunity for examining the differences in the extent of their defense against herbivores because they exhibit sex-related differences in reproductive investment. Such differences enable comparison of the sex with high reproduction expenses with the sex that expends less. The more costly sex is usually also better defended against herbivores. Generally, females are considered more valuable than hermaphrodites in terms of fitness; however, hermaphrodites are more valuable if they can produce seed by autonomous selfing, provided that the inbreeding depression is low and pollen is limited. We studied a gynodioecious population of Opuntia robusta from Central-Eastern Mexico, which has been reported to be trioecious, dioecious, or hermaphrodite, and addressed the following questions: 1) Is the hermaphrodite's reproductive output higher than the female's, and are hermaphrodites thus better defended? 2) Are plant tissues differentially defended? 3) Do trade-offs exist among different physical defense traits? and 4) among physical and chemical defense traits? We found that 1) hermaphrodites had a higher seed output and more spines per areola than females and that their spines contained less moisture. Non-reproductive hermaphrodite cladodes contained more total phenolic compounds (TPCs) than female ones. In addition, 2) hermaphrodite reproductive cladodes bore more spines than female cladodes, and 3) and 4) we found a negative relationship between spine number per areola and areola number per cladode and a positive relationship between spine number per areola per plant and TPC concentration per plant. Non-reproductive hermaphrodite cladodes contained a higher concentration of TPCs than female cladodes, and parental cladodes contained fewer TPCs than both reproductive and empty cladodes.

Protoporphyirin-IX (PP-IX) is a precursor of the biosynthesis of the hemo group, most of the cytochromes and the chlorophylls. The PP-IX is used for medical purposes, and recently a report indicated that it exhibits a dual action since it can decrease or increase the genetic damage caused by N-nitroso-N-ethylurea (ENU) in somatic cells of Drosophila. PP-IX is known to be able to act as an anti-or pro-oxidant agent. The aim of the present research was to study the role of PP-IX on the lifespan of Drosophila melanogaster, taking into account the fact that increasing levels of ROS can accelerate the aging process. The Canton-S strain (CS) was used as well as Sod and Cat which are deficient in the endogenous enzymes, superoxide dismutase and catalase, respectively. Groups of females and males were treated separately with 5 mg/ml of PP-IX solution. The comparison of survival curves indicates that this pigment extended the lifespan of CS. In contrast, Sod strain showed that the opposite effect and had no effect in Cat strain. The fact that PP-IX reduces the mean lifespan in Sod deficient strain might suggest a pro-oxidant action of PP-IX, and consequently the cumulating of ROS as a superoxide could have a mutagenic effect as was shown recently. The results presented evidence of the dual effect of PP-IX.

The effects on the aroma compositions of ethanol extracts obtained by traditional and enzyme-assisted methods from seven killing conditions used in vanilla pod curing were studied. Two procedures of vanilla pod killing consisted of either freezing pods at )10°C for 24 h or immersing pods in 80°C water for 10 s each of three times with 30 s intervals resulted in the highest vanillin values in terms percentage of dry weight of the bean (2.84 and 2.96), 4-hydroxybenzaldehyde (0.18 and 0.20), vanillyl alcohol (0.56 and 0.57) and vanillic acid (0.18 and 0.19 respectively) when traditional vanilla ethanol extraction was used. When this extract was aged for 3 months it showed improvement in flavour compounds. Enzyme-assisted vanilla ethanol extraction showed a higher content of flavour compounds than traditional extract, for example vanillin 4.38% and 2.96% respectively. Only vanillic acid levels were improved after ageing of the enzymeassisted extracts.