The degree to which evolutionary trajectories and outcomes are repeatable across independent populations depends on the relative contribution of selection, chance and history. Population size has been shown theoretically and empirically to affect the amount of variation that arises among independent populations adapting to the same environment. Here, we measure the contribution of selection, chance and history in different-sized experimental populations of the unicellular alga Chlamydomonas reinhardtii adapting to a high salt environment to determine which component of evolution is affected by population size. We find that adaptation to salt is repeatable at the fitness level in medium (N e ¼ 5 Â 10 4 ) and large (N e ¼ 4 Â 10 5 ) populations because of the large contribution of selection. Adaptation is not repeatable in small (N e ¼ 5 Â 10 3 ) populations because of large constraints from history. The threshold between stochastic and deterministic evolution in this case is therefore between effective population sizes of 10 3 and 10 4 . Our results indicate that diversity across populations is more likely to be maintained if they are small. Experimental outcomes in large populations are likely to be robust and can inform our predictions about outcomes in similar situations.

Since the elevated levels of microRNAs (miRNAs) often cause various diseases, selective inhibition of miRNA maturation is an important therapeutic strategy. Commonly used anti-miRNA strategies are limited to targeting of mature miRNAs, as the upstream targeting of miRNA maturation with an oligonucleotide is challenging due to the presence of a stable pre-miRNA stem-loop structure. Previously, we reported that about 16% of known human pre-miRNAs have the potential to adopt G-quadruplex (GQ) structures alternatively to canonical stem-loops. Herein, we showed that a rationally designed locked nucleic acid (LNA) binds specifically the GQ conformation of pre-miRNA 92b and inhibits pre-miRNA maturation. Further, we showed that the LNA treatment rescues PTEN expression in non-small-cell lung cancer (NSCLC) cells, which is suppressed by the elevated level of miRNA 92b. Treatment of LNA significantly decreases the IC of doxorubicin for NSCLC cells. This strategy can be developed as a novel anti-miRNA therapeutic approach to target GQ harboring miRNAs. This can potentially be a more powerful approach than targeting of the mature miRNA, as it is an upstream targeting and can reduce both 3' and the 5' mature miRNA levels at once.

The Next Generation Science Standards (NGSS) chat (#NGSSchat) is a social media-based professional network used to discuss topics related to the NGSS in the United States. While successful reforms involve and coordinate the work of multiple stakeholders, recent research points out a striking lack of coordination between the individuals working in different educational roles—to the detriment of intended changes in the system. In this study, we analyzed more than 7,000 posts from individuals participating in #NGSSchat on Twitter (n = 247) during two years of one-hour synchronous discussions. We studied the depth and types of conversations that took place, the extent to which the involvement of teachers, administrators, researchers, and organizations was balanced, and what explains participation in the network over time. Using a mixed-methods approach involving social network analysis, we found that conversations were primarily transactional, or social, and substantive, or providing opportunities for sense-making about the standards and for participants to transform their practice and that individuals from diverse roles participated, with teachers comprising the plurality of those involved. Additionally, researchers, administrators, and teachers were the most active in the network, with no differences in both initiating, or sending, and being the recipients of, or receiving, replies as a part of conversations. Finally, we found that being a teacher or administrator, as well as receiving replies from individuals who were important in the network, were positively related to sustained involvement in the network in the following year. We discuss how #NGSSchat—as a social media-based professional network—demonstrates similar features in other effective networks, and how social media-based networks invite new visions for how to implement ambitious, large-scale changes in science education.

With # Plate (No. VIII.), and a Section.[Read 8th February, 1897.] SINCE the publication of papers by Sir William Dawson and Professor Penhallow on Parka decipiens, renewed attention has been drawn to the origin and affinities of this deceiving fossil, and though the authors of the present paper had in their own minds been perfectly satisfied with the general conclusions arrived at by these writers, they are aware that doubts are still cast upon the propriety of associating certain stems and leaves with this organism as their fruit. Indeed, one eminent botanist, after all the evidence which has been produced, has been unable to accept it, and still expresses doubts of the vegetable origin of Parka at all.It is principally, then, to meet such objections that the present writers have thought of bringing together, and re-stating, in the following paper, the whole argument in favour of the vegetable origin and rhizocarpian affinities of this remarkable fossil.Parka decipiens was first discovered by Dr. Fleming, who described it in 1831.* It received its generic name from Parkhill, near Newburgh, on the Fife shore of the Firth of Tay, where Dr. Fleming had found it some two years previously in a bed of sandstone which underlies the Ochils, and stretches from Balmerino on the east to Abernethy and Dron on the west. Its specific name was given on account of its deceiving nature, a character which, as we shall see, it has since well maintained.Hugh Miller, in his " Testimony of the Rocks," t quotes Fleming's description of Parka, as follows: -"These organisms occur in the form of circular flat patches, not equalling an inch in diameter, and composed of numerous smaller contiguous pieces. They are not unlike what might be expected to result from a compressed berry, such as the bramble or the rasp. As, however, they are found lying adjacent to the narrow leaves of gramineous [-looking] vegetables, and chiefly in clay slate, originally lacustrine silt, it is probable that they constituted at Carleton University http://trngl.lyellcollection.org/ Downloaded from 106 TRANSACTIONS-GEOLOGICAL SOCIETY OP GLASGOW. the conglobate panicles of extinct species of the genus Junicus or Sparzanium."Sir Charles Lyell, in 1855,* referred to the occurrence of Parka in the sandstones of Fifeshire and Forfarshire, mentioning its resemblance to the eggs of Natica, a gasteropodous mollusc, and also figuring a specimen of the latter to show the resemblance between the two forms. But he says that, as no gasteropodous shells have been detected in the same formation, the Parka has, probably, no connection with this class of organisms. He also cites Mantell's theory of their batrachian origin.Hugh Miller, in 1857,t showed that the egg-theory of the origin of Parka had been first propounded by the quarrymen of Carmylie in Forfarshire, who likened it to "puddock [frog] spawn," an idea which was largely adopted by many of our leading geologists, but he himself favoured the vegetable origin, and compared it to a strawberry or raspberry. We may note here...

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