Ricardo Gómez

The near-neutral model of B chromosome evolution predicts that population invasion is quite fast. To test this prediction, in 1994, we introduced males of the grasshopper Eyprepocnemis plorans from a B-carrying population into a B-lacking population and monitored the evolution of B-chromosome frequency up to 2013. We observed fluctuating very low B frequency across years but, remarkably, the B chromosome introduced (the B2 variant) was found up to 1996 only, whereas the B1 variant was present from 1996 onwards, presumably introduced by fishermen using E. plorans males as bait. Effective introgression of genetic material from the donor population was evidenced by the presence of a satellite DNA on autosome 9 (up to 1999) and the presence of one individual in 2006 showing an ISSR marker profile being highly similar to that found in the donor population. This indicated that the males introduced by us effectively mated with resident females, but donor genes rapidly decreased in frequency after this non-recurrent migration event. Taken together, our results indicated: (i) that the non-recurrent migration event had a slight, transient genetic effect on the recipient population, which was diluted in only a few generations; and (ii) that even with recurrent migration (forced by fishermen) the B chromosome failed to increase in frequency. Bearing in mind that B chromosomes in this species drive through females only, we hypothesize that B chromosomes most likely failed invasion in both migration events because the migrating sex shows no B-drive.

Purpose: The high content of unsaturated fatty acids and the elevated presence of bioactive compounds make pistachio oil a healthy product with great commercial potential. One of the primary constraints for its production is the lack of information regarding oil extraction from an industrial perspective. The purpose of this paper is to ensure the success of pistachio oil production at a commercial scale, attention should be paid to the effect of the main extraction procedures on the characteristics of oil, the consumer acceptance of these oils and their production cost. Design/methodology/approach: Comparison and evaluation of the physicochemical and sensory characteristics and production cost of oil extracted using two different production lines (hydraulic press and screw press) are considered here. Findings: Slight differences were found in the physicochemical analysis, but significant differences were identified in the sensory analysis. Consumer judges preferred the oil extracted with the hydraulic press. According to production costs, the break-even value that makes screw press extraction sustainable is €70.4 per litre, while for the hydraulic press it is €91.0 per litre, mainly due to a lower extraction yield and the longer extraction time required. As production costs of both methods are high, pistachio oil quality should prevail, making the use of the hydraulic press more advisable. Originality/value: Although significant research has been conducted to analyse pistachio oil composition and nutritional value, little attention has been paid to differences that appear regarding consumer preferences and production costs depending on the production method used. This paper provides a comprehensive approach to high-quality pistachio oil production from an industrial perspective.

Most supernumerary (B) chromosomes are parasitic elements carrying out an evolutionary arms race with the standard (A) chromosomes. A variety of weapons for attack and defense have evolved in both contending elements, the most conspicuous being B chromosome drive and A chromosome drive suppression. Here, we show for the first time that most microspermatids formed during spermiogenesis in two grasshopper species contain expulsed B chromosomes. By using DNA probes for B-specific satellite DNAs in Eumigus monticola and Eyprepocnemis plorans, and also 18S rDNA in the latter species, we were able to count the number of B chromosomes in standard spermatids submitted to fluorescence in situ hybridization, as well as visualizing B chromosomes inside most microspermatids. In E. plorans, the presence of B-carrying microspermatids in 1B males was associated with a significant decrease in the proportion of B-carrying standard spermatids. The fact that this decrease was apparent in elongating spermatids but not in round ones demonstrates that meiosis yields 1:1 proportions of 0B and 1B spermatids and hence that B elimination takes place post-meiotically, i.e., during spermiogenesis, implying a 5–25% decrease in B transmission rate. In E. monticola, the B chromosome is mitotically unstable and B number varies between cells within a same individual. A comparison of B frequency between round and elongating spermatids of a same individual revealed a significant 12.3% decrease. We conclude that B chromosome elimination during spermiogenesis is a defense weapon of the host genome to get rid of parasitic chromosomes.

In this paper the extraction methods of virgin almond oil and its chemical composition are reviewed. The most common methods for obtaining oil are solvent extraction, extraction with supercritical fluids (CO2) and pressure systems (hydraulic and screw presses). The best industrial performance, but also the worst oil quality is achieved by using solvents. Oils obtained by this method cannot be considered virgin oils as they are obtained by chemical treatments. Supercritical fluid extraction results in higher quality oils but at a very high price. Extraction by pressing becomes the best option to achieve high quality oils at an affordable price. With regards chemical composition, almond oil is characterized by its low content in saturated fatty acids and the predominance of monounsaturated, especially oleic acid. Furthermore, almond oil contains antioxidants and fat-soluble bioactive compounds that make it an oil with interesting nutritional and cosmetic properties.

Nuts are nutrient dense foods especially appreciated for the fatty acids composition of the oil fraction and other bioactive compounds, like polyphenols or sterols. Almond, pistachio, and walnut oils were extracted by two pressure systems (hydraulic press and screw press) in order to obtain virgin oils. A comparison of the fatty acids was performed for oils from different sources. Although the main components of oils (fatty acids and sterols) did not vary according to the system used, some differences among the three types of nut oils were found. Almond and pistachio oil samples showed a similar fatty acid profile with a substantial amount of monounsaturated fatty acids, 70 and 61%, respectively. However, the majority proportion in walnut oils was the polyunsaturated fatty acids (60%). The highest total sterol content was presented by pistachio oils (4476 mg/kg). Screw press oils showed higher values of the regulated quality parameters (acidity, peroxide value, K₂₃₂, and K₂₇₀). In the same way, polyphenols and oxidative stability were slightly higher when the nut oils were extracted with a screw press.

Purpose: – The purpose of this paper is to analyze the influences of different variables on the dietary adjustment process of international university students. More specifically, the authors investigate how ethnocentrism, perceived risk, and external influences affect their adjustment processes by considering three different temporal stages and exploring adjustment in relation to dietary practices. Design/methodology/approach: – After performing an in-depth review of the relevant literature, a structural equation analysis is conducted. This analysis relies on data from a sample of 139 international students enrolled in a Spanish university. Findings: – The results reveal that ethnocentrism is significant only in the second stage of the adjustment process. The level of perceived risk decreases during the adjustment process but also depends on the features international students have in common with the host culture; in contrast, external influences are important in all stages. Research limitations/implications: – International students should not be treated the same way during different stages of their adjustment. For example, during the first stage, the focus should be on minimizing their perceived risk and guaranteeing a safe environment in which they feel comfortable with buying. The role of the media and the training of salespeople should be highlighted in the second stage of adjustment. Practical implications: – The dietary adjustment for this group of short-term migrants is different than other groups, which tend to return to their country of origin. In contrast, international university students try to assimilate the host culture and be part of it. Social implications: – In the context of consumption, because international university students are influenced by all constructs detailed in this study, it is necessary to formulate a specific approach for each stage. Originality/value: – This research evidences how there is a great opportunity for diverse operators (e.g. universities, food retail chains) to influence the consumption habits of international university students, because they are more receptive than other migrant groups.

Parasitic supernumerary (B) chromosomes show high capability to spread across populations. But the existence of abrupt discontinuities in their distribution demands an explanation. The grasshopper Eyprepocnemis plorans plorans harbour supernumerary chromosomes in all natural populations hitherto analyzed from the Circum-Mediterranean region, with the single exception of the headwaters of the Iberian Segura River and several of its tributaries. To ascertain the causes of this distribution pattern, we analyze here the genetic structure of five natural populations collected in this zone (two +B and three -B), by means of ISSR markers. We found significant population structure, with two kinds of populations coinciding with +B and -B ones, separated by strong barriers to gene flow. This gives strong support to the hypothesis that the non-B populations precede B origin, and that B-carrying individuals from coastal zones have been able to colonize upstream areas, until geographical barriers (usually narrow canyons and arid areas surrounding them) impeded their advance.

This study assesses the influence of ethnocentrism on food buying decisions by a specific group of sojourners—namely, international university students—by distinguishing the results observed in relation to gender differences from those detected without any consideration of gender differences. On the basis of an exhaustive review of relevant literature, this study offers several research hypotheses pertaining to the influence of ethnocentrism on evaluations of alternatives, choices, and post-purchase stages. To test these hypotheses, the authors collected data from a sample of university foreign students enrolled in a Spanish university, and then submitted these data to diverse principal components factorial analyses and linear parametric regressions. The results show that a consideration of gender makes a great difference, in that the influence of ethnocentrism is much greater in the food buying decision process for male sojourners. These results have major implications for key stakeholders such as food manufacturers, importers, retailers, and universities.