Investing in emergent literacy intervention: a key role for speech-language pathologists.

Emergent literacy is a developmental period that is receiving renewed and increased emphasis in the fields of education and speech-language pathology because of its influence on the later literacy development and achievement of students. With their strong background in language, language development, and language disorders, speech-language pathologists (SLPs) can make significant contributions to the acquisition of emergent literacy skills. This article focuses on SLP direct-service roles for students with identified communication impairments and on indirect roles of assisting teachers and others to promote the emergent literacy skills of all students. In addition to the acknowledged importance of general oral language, guidelines, suggestions, and resources are offered to foster emergent literacy skills in five specific areas: (1) early phonological awareness, (2) joint book reading and sense of story, (3) alphabetic letter knowledge, (4) adult modeling of literacy activities, and (5) experience with writing materials.

Redundancy of information in enhancers as a principle of mammalian transcription control.

In contrast to prokaryotes, in which strong transcriptional signals can be located within very short DNA segments, typical mammalian enhancers are about 200 base-pairs long. We reasoned that a minimal length of enhancer-active DNA is required for a high transcription rate in higher eukaryotes, and that segments from a single enhancer or from different enhancers might be multimerized or combined to satisfy such a requirement. To test this, enhancer fragments from different viruses were joined in a recombinant simian virus 40 (SV40) and screened for efficiency of viral growth. The 48 combinations tested show that the hypothesis is basically correct. For example, two subfunctional heterologous enhancer fragments can together form a functional enhancer. No enhancer shorter than 84 base-pairs could promote SV40 growth, i.e. in no case did we find a short "superstrong" enhancer segment. To test whether multimerization of a short fragment would result in a strong enhancer, we have synthesized a 50 base-pair enhancer segment derived from Herpesvirus saimiri. One to six copies of this oligonucleotide gave an incremental increase in enhancer activity. We propose, therefore, that mammalian gene regulation is based on a redundancy of information that can be provided either by a combination of different DNA sequence elements, or by multiple copies of the same element. Also, the finding of strong and weak enhancers suggests that in most cases an enhancer is permanently required for transcription of a gene, rather than acting in an all-or-none fashion to establish a transcription complex, after which it becomes dispensable.