Acclimatization of the tropical reef coral Acropora millepora to hyperthermal stress

The demise of reef-building corals potentially lies on the horizon, given ongoing climate change amid other anthropogenic environmental stressors. If corals cannot acclimatize or adapt to changing conditions, dramatic declines in the extent and health of the living reefs are expected within the next half century. The primary and proximal global threat to corals is climate change. Reef-building corals are dependent upon a nutritional symbiosis with photosynthetic dinoflagellates belonging to the group Symbiodinium. . The symbiosis between the cnidarian host and algal partner is a stress-sensitive relationship; temperatures just 1°C above normal thermal maxima can result in the breakdown of the symbiosis, resulting in coral bleaching (the loss of Symbiodinium and/or associated photopigments) and ultimately, colony death. As ocean temperatures continue to rise, corals will either acclimatize or adapt to changing conditions, or will perish. By experimentally preconditioning the coral Acropora millepora via sublethal heat treatment, the coral acquired thermal tolerance, resisting bleaching during subsequent hyperthermal stress. The complex nature of the coral holobiont translates to multiple possible explanations for acclimatization: acquired thermal tolerance could potentially originate from the host itself, the Symbiodinium, or from the bacterial community associated with the coral. By examining the type of in hospite Symbiodinium and the bacterial community prior acclimation and after thermal challenge, it is shown that short-term acclimatization is not due to a distinct change in the dinoflagellate or prokaryote community. Though the microbial partnerships remain without considerable flux in preconditioned corals, the host transcriptome is dynamic. One dominant pattern was the apparent tuning of gene expression observed between preconditioned and non-preconditioned treatments, showing a modulated transcriptomic response to stress. Additionally several genes were upregulated in association with thermal tolerance, including antiapoptotic genes, lectins, and oxidative stress response genes. Upstream of two of these thermal tolerance genes, inhibitor of NFκB and mannose-binding lectin, DNA polymorphisms were identified which vary significantly between the northern and southern Great Barrier Reef. The impact of these mutations in putative promoter regions remains to be seen, but variation across thermally-disparate geography serves to generate hypotheses regarding the role of regulatory element evolution in a coral adaptation context.

The relationship between the use of Academic Text Talk and the comprehension of scientific academic language for diverse second graders

Changing demographics impact our schools as children come from more linguistically and culturally diverse backgrounds. The various social, cultural, and economic backgrounds of the students affect their early language learning experiences which expose them to the academic language needed to succeed in school. Teachers can help students acquire academic language by introducing words that are within their Zone of Proximal Development and increasing exposure to and use of academic language. This study investigated the effects of increasing structured activities for students to orally interact with informational text on their scientific academic language development and comprehension of expository text. ^ The Academic Text Talk activities, designed to scaffold verbalization of new words and ideas, included discussion, retelling, games, and sentence walls. This study also evaluated if there were differences in scientific language proficiency and comprehension between boys and girls, and between English language learners and native English speakers. ^ A quasi-experimental design was used to determine the relationship between increasing students' oral practice with academic language and their academic language proficiency. Second graders (n = 91) from an urban public school participated in two science units over an 8 week period and were pre and post tested using the Woodcock Muñoz Language Survey-Revised and vocabulary tests from the National Energy Education Project. Analysis of covariance was performed on the pre to post scores by treatment group to determine differences in academic language proficiency for students taught using Academic Text Talk compared to students taught using a text-centered method, using the initial Florida Assessment for Instruction in Reading test as a covariate. Students taught using Academic Text Talk multimodal strategies showed significantly greater increases in their pre to posttest means on the Woodcock Muñoz Language Survey-Revised Oral Language Totals and National Energy Education Development Project Vocabulary tests than students taught using the text-centered method, ps < .05. Boys did not show significantly greater increases than girls, nor did English language learners show significantly greater increases than the native English speakers. ^ This study informs the field of reading research by evaluating the effectiveness of a multimodal combination of strategies emphasizing discourse to build academic language.^