Male fertility advantage within and between seasons in the perennial androdioecious plant Phillyrea angustifolia

BACKGROUND AND AIMS

Androdioecy, the co-occurrence of males and hermaphrodites, is a rare reproductive system. Males can be maintained if they benefit from a higher male fitness than hermaphrodites, referred to as male advantage. Male advantage can emerge from increased fertility owing to resource reallocation. However, empirical studies usually compare sexual phenotypes over a single flowering season, thus ignoring potential cumulative effects over successive seasons in perennials. In this study, we quantify various components of male fertility advantage, both within and between seasons, in the long-lived perennial shrub Phillyrea angustifolia (Oleaceae). Although, owing to a peculiar diallelic self-incompatibility system and female sterility mutation strictly associated with a breakdown of incompatibility, males do not need fertility advantage to persist in this species, this advantage remains an important determinant of their equilibrium frequency.

METHODS

A survey of >1000 full-sib plants allowed us to compare males and hermaphrodites for several components of male fertility. Individuals were characterized for proxies of pollen production and vegetative growth. By analysing maternal progeny, we compared the siring success of males and hermaphrodites. Finally, using a multistate capture-recapture model we assessed, for each sexual morph, how the intensity of flowering in one year impacts next-year growth and reproduction.

KEY RESULTS

Males benefitted from a greater vegetative growth and flowering intensity. Within one season, males sired twice as many seeds as equidistant, compatible hermaphroditic competitors. In addition, males more often maintained intense flowering over successive years. Finally, investment in male reproductive function appeared to differ between the two incompatibility groups of hermaphrodites.

CONCLUSION

Males, by sparing the cost of female reproduction, have a higher flowering frequency and vegetative growth, both of which contribute to male advantage over an individual lifetime. This suggests that studies analysing sexual phenotypes during only single reproductive periods are likely to provide inadequate estimates of male advantage in perennials.

Haplotype-resolved genomes of two buckwheat crops provide insights into their contrasted rutin concentrations and reproductive systems

BACKGROUND

Two widely cultivated annual buckwheat crops, Fagopyrum esculentum and F. tataricum, differ from each other in both rutin concentration and reproductive system. However, the underlying genetic mechanisms remain poorly elucidated.

RESULTS

Here, we report the first haplotype-resolved chromosome-level genome assemblies of the two species. Two haplotype genomes of F. esculentum were assembled as 1.23 and 1.19 Gb with N50 = 9.8 and 12.4 Mb, respectively; the two haplotype genomes of F. tataricum were 453.7 and 446.2 Mb with N50 = 50 and 30 Mb, respectively. We further annotated protein-coding genes of each haplotype genome based on available gene sets and 48 newly sequenced transcriptomes. We found that more repetitive sequences, especially expansion of long terminal repeat retrotransposons (LTR-RTs), contributed to the large genome size of F. esculentum. Based on the well-annotated sequences, gene expressions, and luciferase experiments, we identified the sequence mutations of the promoter regions of two key genes that are likely to have greatly contributed to the high rutin concentration and selfing reproduction in F. tartaricum.

CONCLUSIONS

Our results highlight the importance of high-quality genomes to identify genetic mutations underlying phenotypic differences between closely related species. F. tataricum may have been experienced stronger selection than F. esculentum through choosing these two non-coding alleles for the desired cultivation traits. These findings further suggest that genetic manipulation of the non-coding promoter regions could be widely employed for breeding buckwheat and other crops.

Effects of sub-chronic oral exposure to pyrogenic synthetic amorphous silica (NM-203) in male and female Sprague-Dawley rats: focus on reproductive systems

Synthetic amorphous silica (SAS) consists of agglomerates and aggregates of primary particles in the nanorange (<100 nm) and it is the E551 authorized food additive. The potential risks for human health associated to dietary exposure to SAS are not completely assessed; in particular, data on male and female reproductive systems are lacking. A 90-day oral toxicity study with pyrogenic SAS nanomaterial NM-203 was carried out on the basis of the OECD test guideline 408 in the frame of the NANoREG project. Adult Sprague-Dawley rats of both sexes were orally treated for 90 days with 0, 2, 5, 10, 20 and 50 mg SAS/kg bw per day. Dose levels were selected to be as close as possible to the expected human exposure to food additive E551. The present paper provides specific information on potential effects on male and female reproductive systems, through the evaluation of serum biomarkers, sperm count, histopathological analysis of testis, epididymis, ovary and uterus and real-time PCR on uterus; potential genotoxic alterations were evaluated by comet assay on testis, sperm and ovary. NM-203 did not induce histophatological and genotoxic effects in male reproductive system. In female rats, ovary is not target of NM-203 and only tissue-specific effects on uterus were recorded up to 10 mg/kg bw per day. To our best knowledge, this is the first study providing data on male and female reproductive systems after long-term, repeated oral exposure at dose levels close to dietary human exposure, which identifies a limited concern only for female reproductive health.

Effects of artificial light at night (ALAN) on gene expression of Aquatica ficta firefly larvae

Artificial light at night (ALAN) is a major driver of firefly population declines, but its physiological effects are not well understood. To investigate the impact of ALAN on firefly development, we exposed larval Aquatica ficta fireflies to ALAN for two weeks. High larval mortality was observed in the periods of 1-68 days and 106-134 days post-treatment, which may represent the short- and long-term impacts of ALAN. We then profiled the transcriptome of larval Aquatica ficta fireflies following two weeks of ALAN exposure. A total of 1262 (1.67% out of 75777 unigenes) were differentially expressed in the treatment group: 1157 were down-regulated, and 105 were up-regulated. Up-regulated unigenes were related to regulation of hormone levels, ecdysteroid metabolic process, and response to stimulus; down-regulated unigenes were related to negative regulation of insulin receptor signaling, germ cell development, oogenesis, spermatid development, and regulation of neuron differentiation. Transcriptome results suggest that the endocrine, reproductive, and neural development of firefly larvae could be impaired by even relatively brief period of ALAN exposure. This report contributes a much-needed molecular perspective to the growing body of research documenting the fitness impacts of ALAN on bioluminescent fireflies.

Diagnosing Eulimnadia and Paralimnadia (Branchiopoda: Spinicaudata: Limnadiidae)

Eulimnadia and Paralimnadia are both strongly supported, monophyletic limnadiid lineages based on molecular studies. However, defining the two taxa morphologically relies on the presence/absence of a subcercopodal spiniform projection; otherwise there is considerable overlap and confusion in morphological characters between the two taxa. The most discriminatory of these characters are examined here and applied to Australasian species. As a result, five Eulimnadia species are transferred to Paralimnadia. These characters are then applied to world Eulimnadia species and other limnadiid genera which share key features with Eulimnadia.

De novo transcriptome sequencing and analysis of male and female swimming crab (Portunus trituberculatus) reproductive systems during mating embrace (stage II)

Background

The swimming crab Portunus trituberculatus is one of the most commonly farmed crustaceans in China. As one of the most widely known and high-value edible crabs, it crab supports large crab fishery and aquaculture in China. Only large and sexually mature crabs can provide the greatest economic benefits, suggesting the considerable effect of reproductive system development on fishery. Studies are rarely conducted on the molecular regulatory mechanism underlying the development of the reproductive system during the mating embrace stage in this species. In this study, we used high-throughput sequencing to sequence all transcriptomes of the P. trituberculatus reproductive system.

Results

Transcriptome sequencing of the reproductive system produced 81,688,878 raw reads (38,801,152 and 42,887,726 reads from female and male crabs, respectively). Low-quality (quality <20) reads were trimmed and removed, leaving only high-quality reads (37,020,664 and 41,021,030 from female and male crabs, respectively). A total of 126,188 (female) and 164,616 (male) transcripts were then generated by de novo transcriptome assembly using Trinity. Functional annotation of the obtained unigenes revealed that a large number of key genes and some important pathways may participate in cell proliferation and signal transduction. On the basis of our transcriptome analyses and as confirmed by quantitative real-time PCR, a number of genes potentially involved in the regulation of gonadal development and reproduction of P. trituberculatus were identified: ADRA1B, BAP1, ARL3, and TRPA1.

Conclusion

This study is the first to report on the whole reproductive system transcriptome information in stage II of P. trituberculatus gonadal development and provides rich resources for further studies to elucidate the molecular basis of the development of reproductive systems and reproduction in crabs. The current study can be used to further investigate functional genomics in this species.

Electronic supplementary material

The online version of this article (10.1186/s12863-017-0592-5) contains supplementary material, which is available to authorized users.

Fractional parentage analysis and a scale-free reproductive network of brown trout

In this study, we developed a method of fractional parentage analysis using microsatellite markers. We propose a method for calculating parentage probability, which considers missing data and genotyping errors due to null alleles and other causes, by regarding observed alleles as realizations of random variables which take values in the set of alleles at the locus and developing a method for simultaneously estimating the true and null allele frequencies of all alleles at each locus. We then applied our proposed method to a large sample collected from a wild population of brown trout (Salmo trutta). On analyzing the data using our method, we found that the reproductive success of brown trout obeyed a power law, indicating that when the parent-offspring relationship is regarded as a link, the reproductive system of brown trout is a scale-free network. Characteristics of the reproductive network of brown trout include individuals with large bodies as hubs in the network and different power exponents of degree distributions between males and females.