Summary• Pollinator-mediated selection has been hypothesized as one cause of size dimorphism between female and male flowers. Flower number, ignored in studies of floral dimorphism, may interact with flower size to affect pollinator selectivity.• In the present study, we explored pollinator response, and estimated pollen receipt and removal, in experimental populations of monoecious Sagittaria trifolia , in which plants were manipulated to display three, six, nine or 12 female or male flowers per plant. In this species, female flowers are smaller but have a more compressed flowering period than males, creating larger female floral displays.• Overall, pollinators preferred to visit male rather than female displays of the same size. Both first visit per foraging bout and visitation rates to female displays increased with display size. However, large male displays did not show increased attractiveness to pollinators. A predicted relationship that pollen removal, rather than pollen receipt, is limited by pollinator visitation was confirmed in the experimental populations.• The results suggest that the lack of selection on large male displays may affect the evolution of floral dimorphism in this species.

The rhizobacterium Pseudomonas aeruginosa M18 can produce a broad spectrum of secondary metabolites, including the antibiotics pyoluteorin (Plt) and phenazine-1-carboxylic acid (PCA), hydrogen cyanide, and the siderophores pyoverdine and pyochelin. The antibiotic biosynthesis of M18 is coordinately controlled by multiple distinct regulatory pathways, of which the GacS/GacA system activates Plt biosynthesis but strongly downregulates PCA biosynthesis. Here, we investigated the global influence of a gacA mutation on the M18 transcriptome and related metabolic and physiological processes. Transcriptome profiling revealed that the transcript levels of 839 genes, which account for approximately 15% of the annotated genes in the M18 genome, were significantly influenced by the gacA mutation during the early stationary growth phase of M18. Most secondary metabolic gene clusters, such as pvd, pch, plt, amb, and hcn, were activated by GacA. The GacA regulon also included genes encoding extracellular enzymes and cytochrome oxidases. Interestingly, the primary metabolism involved in the assimilation and metabolism of phosphorus, sulfur, and nitrogen sources was also notably regulated by GacA. Another important category of the GacA regulon was secretion systems, including H1, H2, and H3 (type VI secretion systems [T6SSs]), Hxc (T2SS), and Has and Apr (T1SSs), and CupE and Tad pili. More remarkably, GacA inhibited swimming, swarming, and twitching motilities. Taken together, the Gac-initiated global regulation, which was mostly mediated through multiple regulatory systems or factors, was mainly involved in secondary and primary metabolism, secretion systems, motility, etc., contributing to ecological or nutritional competence, ion homeostasis, and biocontrol in M18. P seudomonas aeruginosa M18 is a unique and well-characterized biocontrol rhizobacterium showing a strong antifungal capability (1, 2). It can produce a diverse range of secondary metabolites, including antibiotics, siderophores, and extracellular enzymes, such as phenazine-1-carboxylic acid (PCA), pyoluteorin (Plt), hydrogen cyanide (HCN), L-2-amino-4-methoxy-trans-3-butenoic acid (AMB), pyoverdine, pyochelin, and alkaline protease (1, 2). In contrast to primary metabolism, which is essential for maintaining normal physiological processes, secondary metabolism is not absolutely required for bacterial survival but contributes to ecological and nutritional competence. AMB, a potent antibiotic and toxin, has received little attention (3). The antibiotics PCA and Plt mainly contribute to the strong antifungal capacity of the M18 strain. In the M18 genome, two copies of phenazine biosynthetic operons are highly homologous to each other and to those in P. aeruginosa PAO1 (2, 4). However, the Plt biosynthetic structural, regulatory, and transport gene cluster is conserved in gene organization and size between P. aeruginosa M18 and P. protegens Pf-5 (previously called P. fluorescens) but displays a certain level of difference in the nucleotide sequence, especially the n...

Summary• Although theoretical models predict low allocation to attractive structures with increased selfing in animal-pollinated plants, empirical measurement of the reproductive costs and benefits is complicated.• Here, floral sex allocation was compared in two nectarless heterandrous species with different mating systems: Monochoria korsakowii (Pontederiaceae), which has moderate outcrossing rates, and Monochoria vaginalis , a predominant selfer. In both species, mirror-image flowers have one large dark-purple anther and five small yellow anthers. Experimental evidence is provided for functional differences between the two sets of anthers using data on pollinator visitation, pollen removal and deposition, and seed set after hand pollinations.• Flower manipulations in bee-pollinated M. korsakowii demonstrated different functions of the two sets of anthers: the yellow (feeding) anthers function to attract pollinators, but have similar pollen performance to the purple (pollinating) anthers. Furthermore, a disproportional reduction in pollen production of the feeding anthers in the selfing species was found. This differential allocation between feeding and pollinating anthers in heterandrous species has not been recognized before.• The finding of reduced allocation to attractive structures with an increase in the rate of self-fertilization supports the theory of sex allocation.

We tested one of the predictions of Brunet and Charlesworth (1995) that relative floral sex allocation will vary temporally with the mating environment and that the form of dichogamy (protandry vs. protogyny) will select for the pattern of variation in male versus female resource allocation. In many hermaphroditic plant species, allocation to female function (ovule number) decreases from early to late flowers within inflorescences as a result of resource limitation or ontogenetic changes. This pattern may obscure the effects of the mating environment and dichogamy on selection for allocation patterns in protandrous species (male allocation increases regardless). By examining a protogynous species the alternative pattern of temporal variation in resource allocation is predicted, namely that allocation to male function should decrease (or female allocation increase) throughout the flowering sequence. This pattern was observed in protogynous Aquilegia yabeana (Ranunculaceae), in which ovule number per flower remained constant whereas pollen number decreased in sequentially blooming flowers. These observations support the temporal sex allocation hypothesis of Brunet and Charlesworth (1995).

Currently, the oxygen evolution reaction (OER) plays a key role in the industrial application of renewable electrochemical technologies. Thus, developing electrocatalysts with high performance and sufficient stability for the OER is urgently pursued. Although perovskite oxides have provided numerous degrees of freedom for enhancing the electrocatalytic activity due to their diversity and flexibility, their investigation for the OER is mostly limited to pseudocubic structures. In this study, a complex perovskite oxide, Ba0.9Sr0.1Co0.8Fe0.1Ir0.1O3−δ (BSCFI-91), with a six-layer hexagonal (6H) structure, is synthesized first, displaying higher OER activity. Based on parent Ba0.9Sr0.1Co0.8Fe0.2O3−δ (BSCF-91), BSCFI-91 is obtained by replacing iron (Fe) with low-level iridium (Ir) doping and produces a current density of 10 mA cm–2 at a low overpotential of 300 mV, a small Tafel slope of 61.2 mV dec–1, and good stability up to 10 h in a 1.0 M KOH electrolyte. The dramatically enhanced OER performance is achieved by optimizing cobalt (Co) valence and highly oxidative oxygen species based on the hexagonal structure. The Ir incorporation facilitated the oxygen (O) p band center approaching to the Fermi level, indicating that BSCFI-91 could be a candidate in the electrocatalyst application. Moreover, this study opens up a new way to design efficient perovskite oxides for OER catalysis in terms of hexagonal crystal structures and composition modulation strategy.

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High-altitude pulmonary edema (HAPE) is a potentially fatal condition, occurring at altitudes greater than 3,000 m and affecting rapidly ascending, non-acclimatized healthy individuals. However, the lack of biomarkers for this disease still constitutes a bottleneck in the clinical diagnosis. Here, ultra-high performance liquid chromatography coupled with Q-TOF mass spectrometry was applied to study plasma metabolite profiling from 57 HAPE and 57 control subjects. 14 differential plasma metabolites responsible for the discrimination between the two groups from discovery set (35 HAPE subjects and 35 healthy controls) were identified. Furthermore, 3 of the 14 metabolites (C8-ceramide, sphingosine and glutamine) were selected as candidate diagnostic biomarkers for HAPE using metabolic pathway impact analysis. The feasibility of using the combination of these three biomarkers for HAPE was evaluated, where the area under the receiver operating characteristic curve (AUC) was 0.981 and 0.942 in the discovery set and the validation set (22 HAPE subjects and 22 healthy controls), respectively. Taken together, these results suggested that this composite plasma metabolite signature may be used in HAPE diagnosis, especially after further investigation and verification with larger samples.