摘要:

AbstractTheIME1gene ofSaccharomyces cerevisiaeencodes a transcription factor that is required for the expression of meiosis‐specific genes. Like many of the genes it regulates,IME1itself is expressed according to the following complex pattern: barely detectable levels during vegetative growth, and high induced levels under starvation conditions, followed by a subsequent decline in the course of meiosis. This report examines the influence ofIme1protein on its own expression, demonstrating feedback regulation. Disruption of eitherIME1orIME2leads to constantly increasing levels ofIme1‐lacZexpression, under meiotic conditions. This apparent negative regulation is due to cis elements in theIME1upstream region, which confer transient meiotic expression to heterologous promoter‐less genes. A specific DNA/protein complex, whose level is transiently increased under meiotic conditions, is detected on this element. Inime1−diploids, the level of this DNA/protein complex increases, without any decline. These results indicate that the transient expression ofIME1is apparently due to transcriptional regulation. This report also presents evidence suggesting that Ime 1p is directly responsible for regulating its own transcription. Positive feedback regulation in mitotic conditions is suggested by the observation that overexpression of Ime 1p leads to increased levels ofIME1‐lacZ. Negative autoregulation in meiotic cultures is demonstrated by the observation that a specific point mutation inIME1, ime1–3, permits expression of meiosis‐specific genes, as well as induction of meiosis, but is defective in negative‐feedback regulation ofIME1. © 1995

ISSN:0192-253X    

DOI:10.1002/dvg.1020160302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractMany mammalian transcription factors, including human and mouse serum response factors (SRFs), are post‐translationally modified with O‐linkedN‐acetylglucosamine monosaccharides on multiple serine and/or threonine residues. Nuclear extracts were prepared from 9.5 to 19 days postcoitum mouse embryos and subsequently were fractionated by wheat germ agglutinin (WGA)‐agarose affinity chromatography. SRF binds WGA‐agarose and apparently is O‐glycosylated. On the other hand, the low molecular weight serum response element (SRE)‐binding proteins, including the previously named band I and band II factors, did not bind WGA‐agarose. Furthermore, we showed that the fastest migrating complex contains the Yin‐Yang 1 (YY1) factor. YY1 binds to the c‐fosSRE and skeletal β‐actin muscle regulatory element (MRE), but not the cardiac β‐actin MRE. Nuclear extracts from NIH/3T3 fibroblasts contain similar, if not identical, SRE‐binding complexes. Besides these SRE‐binding factors, mouse PEA3‐binding factor, presumably an ETS domain‐containing protein, was found to bind SRF protein. This physical interaction, between SRF and ETS domain proteins, was shown to involve the DNA‐binding domain‐containing region of SRF and not the carboxyl‐terminal transac

ISSN:0192-253X    

DOI:10.1002/dvg.1020160303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractWe compared the developmental pattern of expression of the sheep β‐lactoglobulin (BLG), the chimeric BLG/human serum albumin (HSA), and the endogenous murine β‐casein genes in the mammary gland of virgin, pregnant and lactating transgenic mice, both at the RNA (expression) and protein (synthesis and secretion) levels. The BLG and casein genes were expressed at very low levels in virgin animals and during early stages of pregnancy. The increase in the expression of these genes started at the second half of pregnancy and reached a peak between the end of pregnancy and day 10 of lactation. The accumulation of their RNA coincided with that of the corresponding proteins, indicating a transcriptional control of expression of these genes. The expression and secretion patterns of the endogenous casein gene in transgenic and nontransgenic mice were indistinguishable. The hybrid BLG/HSA gene constructs displayed distinct patterns of expression in virgin animals and at early stage of pregnancy, from that of the BLG transgene or the endogenous mouse milk protein gene. High levels of expression (17–60% of that on day 18 of pregnancy) were detected in the mammary gland of virgin animals. At day 5 of pregnancy there was a dramatic decrease in HSA synthesis and secretion in all transgenic strains tested. The down‐regulation, revealed by immunoprecipitation and immunohistochemical studies, demonstrated that at that stage of pregnancy only 10–18% of ductal structures contained HSA expressing cells in contrast to the majority of ducts expressing HSA in virgin animals. These morphological studies also demonstrated that the down‐regulation in HSA synthesis and secretion was correlated with the transition from ducts comprised of a single layer of epithelial cells (characteristic of the virgin state) to ducts composed of multilayers of such cells. In two of the three transgenic strains tested, the down‐regulation at the protein level was associated with a similar decrease in HSA transcripts. In the exceptional strain no. 23, HSA transcripts continued accumulating even at this stage. The differences in the control of expression at the RNA level between these transgenic strains were also confirmed byin situhybridization. Our results suggest the involvement of at least two regulatory mechanisms effective at early stages of gestation in the control of expression/secretion of the HSA transgene targeted for expression in the mammary gland by the BLG milk protein promoter. These putative mechanisms may play key roles in the interplay between normal mammogenesis and lactogenesis. Thus, transgenic mice expressing BLG/HSA gene constructs at early stages of gestation would be valuable in further dissecting these mechanisms. © 1995

ISSN:0192-253X    

DOI:10.1002/dvg.1020160304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractDevelopmental expression of theDrosophila melanogastermetallothioneinMtngene has been analysed. Transcripts of this gene accumulate during the vitellogenic phase of oogenesis in a ring of follicular cells at the oocyte‐nurse cell margin and in the follicular cells surrounding the oocyte. There is also strong expression of theMtngene during the second half of embryogenesis in hemocytes, the endoderm midgut, and Malpighian tubules. A banded expression pattern is observed transiently in the midgut at stage 13. The twoMtnalleles,Mtn1andMtn.3, show quantitative differences in their expression patterns. Copper intoxication of flies does not induce ectopic expression of theMtngene, but rather leads to over‐expression of the gene in the structures where it is normally transcribed.Mtntranscription is not altered in homozygous mutants of four genes (lab, wg, dpp, bap) known to be involved in midgut morphogenesis.Expression ofMtnhas been also studied in six other species of themelanogastersubgroup. This analysis demonstrates that regulation ofMtngene transcription has changed during evolution of theDrosophilalineage. For example,Mtnis expressed specifically in the Malpighian tubules ofD. melanogasterwhile inD. mauritianaandD. sechelliathe amnioserosa is a specific location of expression. Nonetheless, expression ofMtnin the midgut is common to the seven species, suggesting a basic role for the MTN protein during embryogenesis in this organ, possibly in the release of metallic ions from vitellogenins. In contrast, two genes also expressed in the embryonic midgut,labanddFRAdisplay identical patterns in all species of themelanogastersubgroup. The diversity ofMtnpatterns in closely relatedDrosophilaspecies exemplifies the rapid evolution of a gene regulatory system. © 1995 Wiley‐Lis

ISSN:0192-253X    

DOI:10.1002/dvg.1020160305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

Abstracteql(equatorial‐less) is a recessive lethal mutation on the second chromosome of Drosophila melanogasfer. J. Campos‐Ortega found that eql clones in somatic mosaic flies have reduced numbers of photoreceptor cells, and he suggested that only the R1, R6, and R7 photoreceptor cells were missing in this mutant. These photoreceptor cells help to define the inverted orientation of ommatidial facets along the equatorial midline of the fly eye, hence the mutation was named “equatorial‐less”. We have conducted a detailed analysis of the eql mutation, by serial section reconstruction of eql clones marked with bw or w−in somatic mosaic flies. We found that all photoreceptor cell types (Rl–R8) could be deleted by the eql mutation, and in rare cases the number of photoreceptor cells was increased. The apparent lack of photoreceptor cell type specificity was confirmed by our analysis of genetically mosaic facets, which indicated that no single photoreceptor cell, or subset of photoreceptor cells, was uniquely required to express eql Rather, eql appears to function in all photoreceptor cells, and possibly in all eye precursor cells. The distribution of photoreceptor cell numbers in w eql facets was consistent with the hypothesis that each photoreceptor cell was deleted independently of the others. The eql gene is located on the right arm of chromosome 2 at map location 2 − 104.5 ± 0.7 and lies between the polytene chromosome bands 59D8 and 60A7. © 199

ISSN:0192-253X    

DOI:10.1002/dvg.1020160306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractWe compared the levels of growth hormone (GH) mRNA in the pituitary, plasma GH concentration, and altered phenotype in rats heterozygous and homozygous for an antisense RNA transgene targeted to the rat GH gene, with those in nontransgenic rats. We initially investigated whether the transgene promoter, which is connected to four copies of a thyroid hormone response element (TRE) that increases promoter activity, affected in vivo transgene expression in the pituitary of the transgenic rats. Plasma GH concentration correlated negatively with T, injection in surgically thyroidectomized heterozygous transgenic rats. There was a reduction of about ˜35–40% in GH mRNA levels in the pituitary of homozygous animals compared with those in non‐transgenic rats. Plasma GH concentration was significantly ˜25–32 and ˜29–41% lower in heterozygous and homozygous transgenic rats, respectively, compared with that in nontransgenic animals. Furthermore, the growth rates in homozygous transgenic rats were reduced by ˜72–81 and ˜51–70% compared with those of their heterozygous and nontransgenic littermates, respectively. The results of these studies suggested that the biological effect of GH in vivo is modulated dose‐dependently by the antisense RNA transgene. The rat GH gene can therefore be targeted by antisense RNA produced from a transgene, as reflected in the protein and RNA levels. © 1

ISSN:0192-253X    

DOI:10.1002/dvg.1020160307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

摘要:

AbstractWe have used quantitative 2‐D protein electrophoresis and immunoprecipitation to study the patterns of histone ubiquitination at 10 h and 36 h of embryonic development in Strongylocentrotus purpuratus. Variants csH2A, αH2A, βH2A, γH2A, δHA, H2AF./Z, αH2B, βH2B, and γH2B showed up to sevenfold differences in level of monoubiquitination between variants, and individual variants showed up to sixfold changes during development. At 36 h of embryogenesis, the late variants were less ubiquitinated than the early variants, althoug h the overall level of ubiquitination was appreciably greater than at 10 h. Antiubiquitin antibodies were used to precipitate formaldehyde‐fixed chromatin fragments in order to estimate the degree of ubiquitination of the early histone genes. The 5′ regulatory region of the active H3 gene appeared to be at least twice as ubiquitinated as the adjacent upstream spacer. However, the absolute level of ubiquitination of the early histone gene repeat seemed to be independent of transcriptional activity. These results show that variant‐specific ubiquitination of histones is a part of the developmental program in sea urchin embryos, but is not clearly correlated with transcriptional activity of the early histone genes, except perhaps in the regulatory regions. © 1995

ISSN:0192-253X    

DOI:10.1002/dvg.1020160308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY

ISSN:0192-253X    

DOI:10.1002/dvg.1020160301

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1995

数据来源: WILEY