Optical and mid-infrared line emission in nearby Seyfert galaxies

Line ratio diagnostics provide valuable clues on the source of ionizing radiation in galaxies with intense black hole accretion and starbursting events, such as local Seyfert or galaxies at the peak of the star formation history. We aim to provide a reference joint optical and mid-IR analysis for studying AGN identification via line ratios and testing predictions from photoionization models. We obtained homogenous optical spectra with the Southern Africa Large Telescope for 42 Seyfert galaxies with Spitzer/IRS spectroscopy and X-ray to mid-IR multiband data available. After confirming the power of the main optical ([OIII]) and mid-IR ([NeV], [OIV], [NeIII]) emission lines in tracing AGN activity, we explore diagrams based on ratios of optical and mid-IR lines by exploiting photoionization models of different ionizing sources (AGN, star formation and shocks). We find that pure AGN photoionization models are good at reproducing observations of Seyfert galaxies with an AGN fractional contribution to the mid-IR (5-40 micron) emission larger than 50 per cent. For targets with a lower AGN contribution these same models do not fully reproduce the observed mid-IR line ratios. Mid-IR ratios like [NeV]/[NeII], [OIV]/[NeII] and [NeIII]/[NeII] show a dependence on the AGN fractional contribution to the mid-IR unlike optical line ratios. An additional source of ionization, either from star formation or radiative shocks, can help explain the observations in the mid-IR. Among combinations of optical and mid-IR diagnostics in line ratio diagrams, only those involving the [OI]/Halpha ratio are promising diagnostics for simultaneously unraveling the relative role of AGN, star formation and, shocks. A proper identification of the dominant ionizing source would require the exploitation of analysis tools based on advanced statistical techniques as well as spatially resolved data.Comment: 31 pages, 15 figures, 2 tables. Accepted for publication in A&

Linking Self-Incompatibility, Dichogamy, and Flowering Synchrony in Two Euphorbia Species: Alternative Mechanisms for Avoiding Self-Fertilization?

Background: Plant species have several mechanisms to avoid selfing such as dichogamy or a self-incompatibility response. Dichogamy in a single flower may reduce autogamy but, to avoid geitonogamy, plants must show flowering synchronization among all their flowers (i.e. synchronous dichogamy). It is hypothesized that one species would not simultaneously show synchronous dichogamy and self-incompatibility because they are redundant mechanisms to reduce selfing; however, this has not been accurately assessed. Methodology/Principal Findings: This expectation was tested over two years in two natural populations of the closely related Mediterranean spurges Euphorbia boetica and E. nicaeensis, which completely avoid autogamy by protogyny at the cyathia level. Both spurges showed a high population synchrony (Z,79), and their inflorescences flower synchronously. In E. nicaeensis, there was no overlap among the cyathia in anthesis of successive inflorescence levels and the overlap between sexual phases of cyathia of the same inflorescence level was uncommon (4–16%). In contrast, E. boetica showed a high overlap among consecutive inflorescence levels (74–93%) and between sexual phases of cyathia of the same inflorescence level (48–80%). The flowering pattern of both spurges was consistent in the two populations and over the two successive years. A hand-pollination experiment demonstrated that E. nicaeensis was strictly self-compatible whereas E. boetica was partially self-incompatible. Conclusions/Significance: We propose that the complex pattern of synchronized protogyny in E. nicaeensis prevents geitonogamous crosses and, consequently, avoids selfing and inbreeding depression. In E. boetica, a high probability of geitonogamous crosses may occur but, alternatively, this plant escapes selfing through a self-incompatibility response. We posit that synchronous dichogamy and physiological self-incompatibility do not co-occur in the same species because each process is sufficiently effective in avoiding self-fertilization.España Ministerio de Ciencia y Tecnología PLO CGL2005-03731; CGL2008-02533-EEspaña Ministerio de Ciencia y Tecnología MA CGL2009-0825

New insights into the indigenous knowledge of the uses of the common stinging nettle (Urtica massaica Mildbr.) in Rwanda

AbstractThe common stinging nettle (Urtica massaica Mildbr., ‘Igisura’) is one of the popular plants used for multiple purposes in Rwanda. This study aimed to get more insights into indigenous knowledge of the multiple uses of this plant in Rwanda. It was conducted in eleven administrative districts in September 2021. A semi-structured questionnaire was used to conduct in-depth interviews with 124 respondents who were chosen using the snowball sampling technique from locations where the stinging nettle grows or has been domesticated. In addition to face-to-face interviews, personal observations, and group discussions were organized at visited sites. Data were analyzed using SPSS. The uses of the common stinging nettle plant can be grouped into five categories: 1. Human medicine, 2. Veterinary medicine, 3. Human nutrition, 4. Animal feeding, and 5. Others. The stinging nettle is used in the form of cooked leaves (47%), leaf powder (39%), boiled leaves (8%), decoction (4%), infusion (1%), and fibers (1%). Stomach ulcers (37%) and hypertension (15%) are the most predominant diseases treated by stinging nettle products. Nearly all respondents (98%) agreed that domesticating the stinging nettle was important and indicated that they would be ready to grow it if they were assured of the market. Nettle products are widely sought to improve the health and well-being of both humans and animals. Yet, they are still scarce on the market. Hence, there is a need to promote the domestication of stinging nettle to increase its production and availability

New insights into the indigenous knowledge of the uses of the common stinging nettle (<i>Urtica massaica</i> Mildbr.) in Rwanda

The common stinging nettle (Urtica massaica Mildbr., ‘Igisura’) is one of the popular plants used for multiple purposes in Rwanda. This study aimed to get more insights into indigenous knowledge of the multiple uses of this plant in Rwanda. It was conducted in eleven administrative districts in September 2021. A semi-structured questionnaire was used to conduct in-depth interviews with 124 respondents who were chosen using the snowball sampling technique from locations where the stinging nettle grows or has been domesticated. In addition to face-to-face interviews, personal observations, and group discussions were organized at visited sites. Data were analyzed using SPSS. The uses of the common stinging nettle plant can be grouped into five categories: 1. Human medicine, 2. Veterinary medicine, 3. Human nutrition, 4. Animal feeding, and 5. Others. The stinging nettle is used in the form of cooked leaves (47%), leaf powder (39%), boiled leaves (8%), decoction (4%), infusion (1%), and fibers (1%). Stomach ulcers (37%) and hypertension (15%) are the most predominant diseases treated by stinging nettle products. Nearly all respondents (98%) agreed that domesticating the stinging nettle was important and indicated that they would be ready to grow it if they were assured of the market. Nettle products are widely sought to improve the health and well-being of both humans and animals. Yet, they are still scarce on the market. Hence, there is a need to promote the domestication of stinging nettle to increase its production and availability.</p

Does pre-dispersal seed predation limit reproduction and population growth in the alpine clonal plant Geum reptans?

We studied the impact of the seed damaging gall midge larva Geomyia alpina on its perennial alpine host plant Geum reptans. We analysed the effect of seed predation on reproduction by seeds, i.e. seed number, seed mass, and seed viability and on growth and clonal propagation of non-protected plants in comparison to plants protected from predation by an insecticide. Additionally, we assessed the consequences of seed predation for population growth using matrix projection modelling. Seed predation resulted in a decrease in total seed mass per flower head by 23.8% in non-protected plants (P > 0.05). Individual seed mass decreased with increasing infestation intensity (P > 0.05). Seed number remained unaffected because the sucking feeding behaviour by gall midge larvae does not evoke seed abortion. Percent germination of seeds from non-protected plants was reduced by 97.9% compared to seeds from protected plants. According to reduced seed viability, modelling revealed a decrease in population growth rate from lambda= 1.055 to lambda= 1.041. Predation did neither influence total plant biomass nor biomass fractions. But stolon dry-weight of non-protected plants increased by 24.1% (P > 0.05), which may indicate a trade-off between sexual reproduction and clonal propagation. Our results demonstrate that despite substantial reduction of viable seeds, predation by gall midge larvae only slightly affected population growth of G. reptans suggesting that in this alpine species, persistence by longevity and clonal propagation can balance potential seed losses by predation, at least for local population growth