The advantage of sex has been among the most debated issues in biology. Surprisingly, the question of why sexual reproduction generally requires the combination of distinct gamete classes, such as ...small and large gametes, or gametes with different mating types, has been much less investigated. Why do systems with alternative gamete classes (i.e. systems with either anisogamy or mating types or both) appear even though they restrict the probability of finding a compatible mating partner? Why does the number of gamete classes vary from zero to thousands, with most often only two classes? We review here the hypotheses proposed to explain the origin, maintenance, number, and loss of gamete classes. We argue that fungi represent highly suitable models to help resolve issues related to the evolution of distinct gamete classes, because the number of mating types vary from zero to thousands across taxa, anisogamy is present or not, and because there are frequent transitions between these conditions. We review the nature and number of gamete classes in fungi, and we attempt to draw inferences from these data on the evolutionary forces responsible for their appearance, loss or maintenance, and number.
Weekly data from 7 years (2004–2010) of primary-care counts of acute respiratory illnesses (ARIs) and local weather readings were used to adjust a multivariate time-series vector error correction ...model with covariates (VECMX). Weather variables were included through a partial least squares index that consisted of weekly minimum temperature (coefficient = − 0·26), weekly median of relative humidity (coefficient = 0·22) and weekly accumulated rainfall (coefficient = 0·5). The VECMX long-term test reported significance for trend (0·01, P = 0·00) and weather index (1·69, P = 0·00). Short-term relationship was influenced by seasonality. The model accounted for 76% of the variability in the series (adj. R
2 = 0·76), and the co-integration diagnostics confirmed its appropriateness. The procedure is easily reproducible by researchers in all climates, can be used to identify relevant weather fluctuations affecting the incidence of ARIs, and could help clarify the influence of contact rates on the spread of these diseases.
Domestication is an excellent model for studies of adaptation because it involves recent and strong selection on a few, identified traits 1–5. Few studies have focused on the domestication of fungi, ...with notable exceptions 6–11, despite their importance to bioindustry 12 and to a general understanding of adaptation in eukaryotes 5. Penicillium fungi are ubiquitous molds among which two distantly related species have been independently selected for cheese making—P. roqueforti for blue cheeses like Roquefort and P. camemberti for soft cheeses like Camembert. The selected traits include morphology, aromatic profile, lipolytic and proteolytic activities, and ability to grow at low temperatures, in a matrix containing bacterial and fungal competitors 13–15. By comparing the genomes of ten Penicillium species, we show that adaptation to cheese was associated with multiple recent horizontal transfers of large genomic regions carrying crucial metabolic genes. We identified seven horizontally transferred regions (HTRs) spanning more than 10 kb each, flanked by specific transposable elements, and displaying nearly 100% identity between distant Penicillium species. Two HTRs carried genes with functions involved in the utilization of cheese nutrients or competition and were found nearly identical in multiple strains and species of cheese-associated Penicillium fungi, indicating recent selective sweeps; they were experimentally associated with faster growth and greater competitiveness on cheese and contained genes highly expressed in the early stage of cheese maturation. These findings have industrial and food safety implications and improve our understanding of the processes of adaptation to rapid environmental changes.
•New HTRs are found in cheese fungi•HTRs are flanked by specific transposable elements•HTRs have spread in cheese-associated fungi through recent selective sweeps•Experiments link two HTRs to growth and competitive advantages on cheese
Ropars et al. report newly discovered horizontally transferred regions, flanked by specific transposable elements that allow cheese-making fungi and food spoilers to grow faster and be better competitors on cheese. These findings have industrial and food safety implications and also improve our understanding of adaptation processes.
Female fecundity advantage in gynodioecious plants is required for the spread and maintenance of this reproductive system. However, not all reproductive characters show female advantage in all ...species. We used a meta-analysis to summarise differences between females and hermaphrodites reported from the literature for several reproductive traits. Further we tested three hypotheses, (1) that female plants of species with many ovules produce more seeds per fruit while those with few ovules produce heavier seeds, (2) that females are more pollen limited than hermaphrodites, and (3) that floral sexual size dimorphism is more pronounced in species with few ovules, either because female reproductive success is less limited by pollen availability in such species or because flowers with few ovules require a smaller floral structure to protect the carpels. Overall, females compared to hermaphrodites produced more but smaller flowers, had higher fruit set, higher total seed production, and produced heavier seeds that germinated better. Species with many versus few ovules differed in female advantage for flower size dimorphism, flower number, fruit set and total seed production. However seed size, seed set per fruit and seed germination differences between females and hermaphrodites did not differ significantly between species with few and many ovules. We also found no evidence for differential pollen limitation between females and hermaphrodites. Degree of floral sexual size dimorphism differed significantly between species with few and many ovules. Though pistillate flowers were generally smaller than those of hermaphrodites, species with many ovules showed less difference in flower size between the sexes, suggesting either that the protective role of the perianth constrains the evolution of sexual size dimorphism in species with many ovules or that selection for adequate pollination in species with many ovules impedes the reduction in flower size of females.
The incidence of nonalcoholic fatty liver disease (NAFLD) is highest among Mexican‐origin (MO) adults. Few studies have estimated the prevalence of NAFLD in this subpopulation, particularly by sex ...and age. We assessed the prevalence of NAFLD in a community sample of MO adults residing in a border region of southern Arizona and determined risk factors associated with NAFLD. A total of 307 MO adults (n = 194 women; n = 113 men) with overweight or obesity completed an in‐person study visit, including vibration‐controlled transient elastography (FibroScan) for the assessment of NAFLD status. A continuous attenuation parameter score of ≥288 dB/m (≥5% hepatic steatosis) indicated NAFLD status. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for NAFLD. We identified 155 participants (50%) with NAFLD, including 52% of women and 48% of men; there were no sex differences in steatosis (men, 287.8 dB/m; women, 288.4 dB/m). Sex, age, patatin‐like phospholipase domain containing 3 (PNPLA3) risk allele carrier status, comorbidities, and cultural and behavioral variables were not associated with NAFLD status. There was some evidence for effect modification of body mass index (BMI) by sex (Pinteraction = 0.08). The estimated OR for an increase in BMI of 5 kg/m2 was 3.36 (95% CI, 1.90, 5.91) for men and 1.92 (95% CI, 1.40, 2.64) for women. In post hoc analyses treating steatosis as a continuous variable in a linear regression, significant effect modification was found for BMI by sex (Pinteraction = 0.03), age (P = 0.05), and PNPLA3 risk allele carrier status (P = 0.02). Conclusion: Lifestyle interventions to reduce body weight, with consideration of age and genetic risk status, are needed to stem the higher rates of NAFLD observed for MO populations.
Although most eukaryotes reproduce sexually at some moment of their life cycle, as much as a fifth of fungal species were thought to reproduce exclusively asexually. Nevertheless, recent studies have ...revealed the occurrence of sex in some of these supposedly asexual species. For industrially relevant fungi, for which inoculums are produced by clonal-subcultures since decades, the potentiality for sex is of great interest for strain improvement strategies. Here, we investigated the sexual capability of the fungus Penicillium roqueforti, used as starter for blue cheese production. We present indirect evidence suggesting that recombination could be occurring in this species. The screening of a large sample of strains isolated from diverse substrates throughout the world revealed the existence of individuals of both mating types, even in the very same cheese. The MAT genes, involved in fungal sexual compatibility, appeared to evolve under purifying selection, suggesting that they are still functional. The examination of the recently sequenced genome of the FM 164 cheese strain enabled the identification of the most important genes known to be involved in meiosis, which were found to be highly conserved. Linkage disequilibria were not significant among three of the six marker pairs and 11 out of the 16 possible allelic combinations were found in the dataset. Finally, the detection of signatures of repeat induced point mutations (RIP) in repeated sequences and transposable elements reinforces the conclusion that P. roqueforti underwent more or less recent sex events. In this species of high industrial importance, the induction of a sexual cycle would open the possibility of generating new genotypes that would be extremely useful to diversify cheese products.
The research addresses an analysis of the level of contamination generated by the gases produced when applying low-pressure cold plasma in a cleaning process of metal sheets used in the manufacture ...of white goods. A mixture of argon and oxygen ionized gases at 50% was utilized to break down the lubricating oil molecules deposited on the surface of the sheet metal. A statistically significant number of samples were selected, with different volumes of oil on the surface, between 6 ml and 34 ml. The samples were later subjected to a plasma discharge with a time of 72 s, a gas pressure of 0.6 bar and 50% power to determine the correlation of the oil volume with the levels of gases generated by the discharge, maintaining the degree of surface cleanliness, as given by contact angle values between 67.5 and 79 degrees, constant. For the analysis of results a Pearson correlation was applied for each detected gas. An analysis was later conducted of the relationship between the degree of cleanliness of the metallic surface, as given by contact angles at 16, 36 and 53 degrees, with the levels of the gases generated by the plasma discharge, keeping the volume of the lubricating oil on the surface constant at 5 ml. For the analyses, statistical tests were carried out to find the correlation between the predictor variables and the dependent variable to establish a multivariate linear statistical model. The results allowed the behavior of the level of contamination to be determined, establishing that the volume of oil does not influence the level of the gases generated by the use of low-pressure cold plasma. The results obtained allow us to understand the relationship between the contact angle that represents the quality of surface cleaning of oil-impregnated sheet metal and the level of contamination generated in the process.
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