High endoreduplication after drought-related conditions in haploid but not diploid mosses.

BACKGROUND AND AIMS: Endoreduplication, the duplication of the nuclear genome without mitosis, is a common process in plants, especially in angiosperms and mosses. Accumulating evidence supports the relationship between endoreduplication and plastic responses to stress factors. Here, we investigated the level of endoreduplication in Ceratodon (Bryophyta), which includes the model organism Ceratodon purpureus. METHODS: We used flow cytometry to estimate the DNA content of 294 samples from 67 localities and found three well-defined cytotypes, two haploids and one diploid, the haploids corresponding to C. purpureus and Ceratodon amazonum, and the diploid to Ceratodon conicus, recombination occurring between the former two. KEY RESULTS: The endoreduplication index (EI) was significantly different for each cytotype, being higher in the two haploids. In addition, the EI of the haploids was higher during the hot and dry periods typical of the Mediterranean summer than during spring, whereas the EI of the diploid cytotype did not differ between seasons. CONCLUSIONS: Endopolyploidy may be essential in haploid mosses to buffer periods of drought and to respond rapidly to desiccation events. Our results also suggest that the EI is closely related to the basic ploidy level, but less so to the nuclear DNA content as previously suggested.

Dietary anhydrous milk fat naturally enriched with conjugated linoleic acid and vaccenic acid modify cardiovascular risk biomarkers in spontaneously hypertensive rats.

Saturated and trans fatty acids have been associated with the risk to develop cardiovascular diseases. However, health-promoting effects are associated with consumption of anhydrous milk fat (AMF) and ruminant trans fatty acids, such as conjugated linoleic acid (CLA) and vaccenic acid (VA) contained in the lipid fraction of milk and dairy products. The purpose of this study was to evaluate the effect of AMF naturally enriched with CLA and VA in spontaneously hypertensive rats (SHR), using sterculic oil to inhibit the conversion of VA into CLA. The administration of AMF to SHR during 7 weeks exerted beneficial effects on cardiovascular risk biomarkers (reduction of insulin, blood lipids, increase of adiponectin). When sterculic oil was included, some parameters were further ameliorated (reduction of insulin, increase of adiponectin). Sterculic oil alone reduced body weight and adiposity, and improved blood pressure, adiponectin and triglyceride levels.

Effect of high hydrostatic pressure on the physiology of Manila mango.

Manila mangoes (Mangifera indica L.) have sensory characteristics that make them attractive for consumption as a fresh fruit. A large portion of the annual yield of this fruit is infested by the Mexican fruit fly (Anastrepha ludens), adversely impacting the quality of the crop. Hence, it is necessary to develop economically viable postharvest treatments to reduce the damage caused by this insect. Currently, high hydrostatic pressures are used to guarantee the safety of many processed foods. The objective of this work was to assess the effects of high hydrostatic pressure on mangoes at their physiological maturity. High hydrostatic pressures were applied to mangoes at three levels: 50, 100 and 200 megapascals applied for four different time periods (0, 5, 10 and 20 min). Physiologically mature mangoes were more resistant to changes in response to the pressure of 50 MPa. Reduction of physiological activity by application of high hydrostatic pressure opens a new avenue for the research on treatments intended to enhance preservation of whole fresh fruit.

Genomic scanning using AFLP to detect loci under selection in the moss Funaria hygrometrica along a climate gradient in the Sierra Nevada Mountains, Spain.

The common cord moss Funaria hygrometrica has a worldwide distribution and thrives in a wide variety of environments. Here, we studied the genetic diversity in F. hygrometrica along an abiotic gradient in the Mediterranean high mountain of Sierra Nevada (Spain) using a genome scan method. Eighty-four samples from 17 locations from 24 to 2700 m were fingerprinted based on their amplified fragment length polymorphism (AFLP) banding pattern. Using PCA and Bayesian inference we found that the genetic diversity was structured in three or four clusters, respectively. Using a genome scan method we identified 13 outlier loci, which showed a signature of positive selection. Partial Mantel tests were performed between the Euclidean distance matrices of geographic and climatic variables, versus the pair-wise genetic distance of the AFLP dataset and AFLP-positive outliers dataset. AFLP-positive outlier data were significantly correlated with the gradient of the climatic variables, suggesting adaptive variation among populations of F. hygrometrica along the Sierra Nevada Mountains. We highlight the additional analyses necessary to identify the nature of these loci, and their biological role in the adaptation process.

How to define nativeness in vagile organisms: lessons from the cosmopolitan moss Bryum argenteum on the island of Tenerife (Canary Islands).

The distinction between native and introduced biotas presents unique challenges that culminate in organisms with high long-distance dispersal capacities in a rapidly changing world. Bryophytes, in particular, exhibit large distribution ranges, and some species can truly be qualified as cosmopolitan. Cosmopolitan species, however, typically occur in disturbed environments, raising the question of their nativeness throughout their range. Here, we employ genetic data to address the question of the origin of the cosmopolitan, weedy moss Bryum argenteum on the island of Tenerife. The genetic diversity of B. argenteum on Tenerife was comparable to that found in continental areas due to recurrent colonisation events, erasing any signature of a bottleneck that would be expected in the case of a recent colonisation event. The molecular dating analyses indicated that the first colonisation of the island took place more than 100,000 years ago, i.e. well before the first human settlements. Furthermore, the significant signal for isolation-by-distance found in B. argenteum within Tenerife points to the substantial role of genetic drift in establishing the observed patterns of genetic variation. Together, the results support the hypothesis that B. argenteum is native on Tenerife; although the existence of haplotypes shared between Tenerife and continental areas suggests that more recent, potentially man-mediated introduction also took place. While defining nativeness in organisms that are not deliberately introduced, and wherein the fossil record is extremely scarce, is an exceedingly challenging task, our results suggest that population genetic analyses can represent a useful tool to help distinguish native from alien populations.

Dietary fatty acids effects on sucrose-induced cardiovascular syndrome in rats.

Cardiovascular disease is one of the leading causes of morbidity and mortality in Mexico. We investigated the effects of omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids on the metabolic syndrome associated with cardiovascular disease in a high-sucrose-fed rat model. The metabolic syndrome-induced rats showed a significant increase in systolic blood pressure, serum insulin, nonfasting serum triglyceride and serum cholesterol levels. Experimental high-sucrose-fed animals received either a n-3 or n-6 enriched diet or a control diet during 6 weeks. Animals fed the n-3 enriched diet had a significant reduction in blood pressure and serum insulin and triglyceride levels. Serum triglyceride levels were also significantly reduced in the n-6-rich diet animals.