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Expression of two Saccharomyces cerevisiae genes (YGIOJ and YG103) The genomes of a wide variety of plant, animal, and bacterial species contain genes related to the major heatinducible gene (hsp70) of Drosophila inelanogasteie, the organism in which the heat shock response has been most thoroughly studied (2). The procaryote Escherichia coli has a single related gene, dnaK (3), which is expressed abundantly under all growth conditions (12). DnaK is about the seventh most abundant protein by weight fraction during growth at 30°C. Furthermore, DnaK is a heat shock protein, its rate of synthesis being rapidly and transiently enhanced upon temperature upshift. Eucaryotes have evolved familie's of related genes, some of which are expressed only after a temperature upshift, while others are expressed under normal steady-state growth conditions. Multigene families have been identified in yeast, fruit fly, mouse, and human cells (5,13,14,21,36 its transcription is enhanced during a heat shock (9). Strains containing mutations in either YGIOO or YG102 show no obvious phenotype, but strains lacking both wild-type YGIOO and YG102 genes have dramatically altered growth properties. Although growth is slower at all temperatures, the severity of the effect increases with increasing temperatures; the double-mutation strain is unable to form colonies at 37°C (6). Here we report the construction and analysis of mutations in two other closely related members of the family. YGIOI and YG103. Unlike other members of the family, expression of these two genes is repressed upon a temperature upshift.The function of the hsp70-related genes as well as other heat shock genes remains obscure. Although it is known that DnaK is required for replication of phage X (11, 30), its role in the metabolism of the host is not clear. In eucaryotes, the question arises as to whether the related proteins perform the same or distinct functions.' We seek here to determine whether a protein whose expression is decreased upon a temperature upshift is 'functionally distinct from a protein whose expression is enhanced.MATERIALS AND METHODS Strains, culture conditions, and transformation. The S.cerei'isiae strains used in this study are listed in Table 1. Transformations were carried out using LiCl as previously described (6). The yeast culture media used in this study have been described previously (6, 31).Hybridization analysis. DNA was isolated from yeast cells as described (6,31)

Expression of two Saccharomyces cerevisiae genes (YG101 and YG103) that are related to the gene encoding inducible 70K protein (hsp70) is repressed upon heat shock. Mutations of the two genes were constructed in vitro and substituted into the yeast genome in place of the wild-type alleles. No phenotypic effect of single mutations of either gene was detected. However, cells containing both YG101 and YG103 mutations showed altered growth properties; double-mutation cells possess an optimal growth temperature of 37 degrees C rather than 30 degrees C and grow increasingly poorly as the temperature is lowered. Mutations of two other members of this hsp70-related multigene family, YG100 and YG102, have been analyzed (E. A. Craig and K. Jacobsen, Cell 38:841-849, 1984). Cells containing both YG100 and YG102 mutations cannot form colonies at 37 degrees C. Fusions between the YG101 and YG102 promoter regions and the YG100 and YG101 structural genes, respectively, were constructed. The YG101 promoter-YG100 structural gene fusion was not able to restore normal growth properties to the yg101- yg103- mutant. Also, yg100- yg102- cells containing the YG102 promoter-YG101 structural gene fusion were unable to grow at 37 degrees C. Failure of the protein products of related genes to rescue the relative cold sensitivity of growth suggests that members of the hsp70 multigene family are functionally distinct.

Rett syndmme -Preserved speech i So far the Norwegian series of listed females with a verified or tentative diagnosis of Rett syndrome comprises 94 individuals (October 1994). Wty-one of these have been thoroughly' assessed, both clinicaJly, neurophysiologically and biochemically. ?kro individuals did not fulfil the criteria of Rett syndrome, and were excluded. Hence, the present sample cornprises 49 females.Since early diagnosis is usually considered tentative, a l l girls included were above 2 '/2 years. The mean age was 1 ]/a ( y d m o n t h s ) and the range was 2/7-46/11, Tlmty-six of the females fulfilled the critmia of classical Rett syndrome, and 13 belong to the Reff variant group (1). Three of them were c I W e d as having the forme h t e variant with a more mdd and protracted clinical course. Six girls showed congenital o w t , two of them were sisters. Two of the females have the early onset variant, and finally two @rk have the preserved speech variant.The sample presented comprises a substantial part of the known Norwegian population of girls and women with Rett syndrome. It includes fewer than expected forme hste variants. The reasons for this may be that the delineation towards other variants can be d~£6cult to draw (e.9. towards the early seizure variant and the p& s p x h variant). Another possibility is that the age dstribution is skewed, favoring females with earlier onsets. It might also be that the forme fruste variants have a different genetic etiology than classical Rett syndrome, and therefore have a different incidence in different geographical areas.The fact that six &Is belong to the congenital variant implies that h c i a n s should be aware of Reff syndrome syrnptomatology even in girls who appeared delayed h m birth.The developmental and the present chical status of the two girls with prae.mil speech revealed symptoms and signs convincing of Rett syndrome. The speech of one of the girls, aged 16 years, is characterized by echolalia and little spontaneous use. It consists mainly of short sentences, typically repeating parts h m the same narratives, such as Winnie the Pooh, for many years. Most utterances appear in ritualized dialogues that are initiated by a partner -usually one of the parents -who facilitates the girl's speech by beghning utterances that she finishes. Although these dialogues may contain considerable variation in vocabulary use, the only genuinely self-initiated utterances are "I am hungry" and "I am thirsty".The other girl is five years old. She used several words at eight months, and long sentences before speech became sparse and was reduced to babbling mund two years of age. She started to speak again at 3 '/2 years, initially with single-word utterances, and mainly to express needs. At the age of five years she speaks in short sentences, but still only to express needs.In spite of their much larger speech repertoire than other females with Rett syndrome, the two girls with preserved speech have limited pragmatic functions, and truly spontaneous speech is mainly ...

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