ALBERT

Description: 〈p〉Plant life cycles alternate between haploid gametophytes and diploid sporophytes. While regulatory factors determining male and female sexual morphologies have been identified for sporophytic reproductive organs, such as stamens and pistils of angiosperms, those regulating sex-specific traits in the haploid gametophytes that produce male and female gametes and hence are central to plant sexual reproduction are poorly understood. Here, we identified a MYB-type transcription factor, MpFGMYB, as a key regulator of female sexual differentiation in the haploid-dominant dioicous liverwort, 〈i〉Marchantia polymorpha〈/i〉. MpFGMYB is specifically expressed in females and its loss resulted in female-to-male sex conversion. Strikingly, Mp〈i〉FGMYB〈/i〉 expression is suppressed in males by a 〈i〉cis〈/i〉-acting antisense gene 〈i〉SUF〈/i〉 at the same locus, and loss-of-function 〈i〉suf〈/i〉 mutations resulted in male-to-female sex conversion. Thus, the bidirectional transcription module at the Mp〈i〉FGMYB/SUF〈/i〉 locus acts as a toggle between female and male sexual differentiation in 〈i〉M. polymorpha〈/i〉 gametophytes. 〈i〉Arabidopsis thaliana〈/i〉 Mp〈i〉FGMYB〈/i〉 orthologs are known to be expressed in embryo sacs and promote their development. Thus, phylogenetically related MYB transcription factors regulate female gametophyte development across land plants.〈/p〉

Description: 〈sec〉〈st〉Synopsis〈/st〉〈p〉〈textbox textbox-type="graphic"〉〈p〉〈inline-fig〉〈/inline-fig〉〈/p〉〈/textbox〉〈/p〉 〈p〉The basal land plant liverwort spends most of its life cycle in a haploid state with distinct male and female morphology. A conserved MYB-type transcription factor regulates the sexual differentiation process, suggesting a shared origin for gamete formation in plants.〈/p〉 〈p〉 〈l type="unord"〉〈li〉〈p〉The autosomal MpFGMYB gene promotes female sexual differentiation in the liverwort 〈i〉Marchantia polymorpha〈/i〉.〈/p〉〈/li〉 〈li〉〈p〉MpFGMYB belongs to a MYB subfamily whose members are known to regulate female gametophyte development in 〈i〉Arabidopsis thaliana〈/i〉.〈/p〉〈/li〉 〈li〉〈p〉Expression of MpFGMYB is suppressed in males by its antisense gene SUF〈i〉in cis〈/i〉.〈/p〉〈/li〉 〈li〉〈p〉Loss-of-function mutations of either MpFGMYB in females or SUF in males leads to near-complete sex conversion phenotypes.〈/p〉〈/li〉〈/l〉 〈/p〉〈/sec〉

Description: Following the 2009 L'Aquila earthquake, the Dipartimento della Protezione Civile Italiana (DPC), appointed an International Commission on Earthquake Forecasting for Civil Protection (ICEF) to report on the current state of knowledge of short-term prediction and forecasting of tectonic earthquakes and indicate guidelines for utilization of possible forerunners of large earthquakes to drive civil protection actions, including the use of probabilistic seismic hazard analysis in the wake of a large earthquake. The ICEF reviewed research on earthquake prediction and forecasting, drawing from developments in seismically active regions worldwide. A prediction is defined as a deterministic statement that a future earthquake will or will not occur in a particular geographic region, time window, and magnitude range, whereas a forecast gives a probability (greater than zero but less than one) that such an event will occur. Earthquake predictability, the degree to which the future occurrence of earthquakes can be determined from the observable behavior of earthquake systems, is poorly understood. This lack of understanding is reflected in the inability to reliably predict large earthquakes in seismically active regions on short time scales. Most proposed prediction methods rely on the concept of a diagnostic precursor; i.e., some kind of signal observable before earthquakes that indicates with high probability the location, time, and magnitude of an impending event. Precursor methods reviewed here include changes in strain rates, seismic wave speeds, and electrical conductivity; variations of radon concentrations in groundwater, soil, and air; fluctuations in groundwater levels; electromagnetic variations near and above Earth's surface; thermal anomalies; anomalous animal behavior; and seismicity patterns. The search for diagnostic precursors has not yet produced a successful short-term prediction scheme. Therefore, this report focuses on operational earthquake forecasting as the principle means for gathering and disseminating authoritative information about time-dependent seismic hazards to help communities prepare for potentially destructive earthquakes. On short time scales of days and weeks, earthquake sequences show clustering in space and time, as indicated by the aftershocks triggered by large events. Statistical descriptions of clustering explain many features observed in seismicity catalogs, and they can be used to construct forecasts that indicate how earthquake probabilities change over the short term. Properly applied, short-term forecasts have operational utility; for example, in anticipating aftershocks that follow large earthquakes. Although the value of long-term forecasts for ensuring seismic safety is clear, the interpretation of short-term forecasts is problematic, because earthquake probabilities may vary over orders of magnitude but typically remain low in an absolute sense (〈 1% per day). Translating such low-probability forecasts into effective decision-making is a difficult challenge. Reports on the current utilization operational forecasting in earthquake risk management were compiled for six countries with high seismic risk: China, Greece, Italy, Japan, Russia, United States. Long-term models are currently the most important forecasting tools for civil protection against earthquake damage, because they guide earthquake safety provisions of building codes, performance-based seismic design, and other risk-reducing engineering practices, such as retrofitting to correct design flaws in older buildings. Short-term forecasting of aftershocks is practiced by several countries among those surveyed, but operational earthquake forecasting has not been fully implemented (i.e., regularly updated and on a national scale) in any of them. Based on the experience accumulated in seismically active regions, the ICEF has provided to DPC a set of recommendations on the utilization of operational forecasting in Italy, which may also be useful in other countries. The public should be provided with open sources of information about the short-term probabilities of future earthquakes that are authoritative, scientific, consistent, and timely. Advisories should be based on operationally qualified, regularly updated seismicity forecasting systems that have been rigorously reviewed and updated by experts in the creation, delivery, and utility of earthquake information. The quality of all operational models should be evaluated for reliability and skill by retrospective testing, and they should be under continuous prospective testing against established long-term forecasts and alternative time-dependent models. Alert procedures should be standardized to facilitate decisions at different levels of government and among the public. Earthquake probability thresholds should be established to guide alert levels based on objective analysis of costs and benefits, as well as the less tangible aspects of value-of-information, such as gains in psychological preparedness and resilience. The principles of effective public communication established by social science research should be applied to the delivery of seismic hazard information.

Description: Published

Description: 315-391

Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale

Description: JCR Journal

Description: open