bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatial regulation in the expression of structural and regulatory storage‐protein genes in Zea mays endosperm
Authors: Dolfini Silvana Faccio , Landoni Michela , Tonelli Chiara , Bernard Loris , Viotti Angelo 
Published: May 2005

AbstractEndosperm development in maize seed involves the multiplication, enlargement, and differentiation of cells with consequent accumulation of storage products. The storage protein genes, encoding zeins, and glutelins (multigene families) are expressed and developmentally regulated by different loci. Wild‐type lines and genotypes carrying mutations at loci affecting zein synthesis (o2, o7, fl2, and prol) were characterized at the molecular level and investigated by Northern analysis in order to define the expression of structural and regulatory genes. In situ hybridization in both wild‐type and mutant lines was performed to visualize the spatial distribution of transcripts representing each gene family, during endosperm development. The zein and glutelin mRNAs are expressed in all endosperm cells, except for the aleurone layer. However, each mRNA type accumulates at a different level in the various endosperm regions, thus allowing to recognize specific territories of expression for each storage protein mRNA within the tissue. The spatial expression patterns appear early for each gene type and are maintained during the course of endosperm development. Also, the quantitative distribution of the same transcripts in endosperm of mutant lines is specific for each mutant and different from that of the wild‐type. Furthermore, the amount of the O2 transcript, present in the nucleus and cytoplasm of wild‐type cells, varies substantially in the different o2 mutations considered, in one mutant almost exclusively confined within the nucleus. These data suggest a specific control of the spatial expression of storage protein genes and a heterogeneous molecular composition of protein bodies throughout the endosperm tissue. © 1992 Wiley‐Liss, Inc.
Developmental regulation of excision timing of Mutator transposons of maize: Comparison of standard lines and an early excision bzl::Mu1 line
Authors: Walbot Virginia 
Published: May 2005

AbstractThree characteristics of standard Mutator lines reflect developmental regulation: new mutants usually involve single gametes, somatic excision is restricted to terminal cell divisions during tissue development, and germinal excision is rare. By selection for earlier (larger) somatic sectors in the aleurone, a Mutator line was identified that exhibits a dramatic elevation in somatic excision frequency during the first three nuclear divisions of the endosperm and more than a 10‐fold increase in germinal reversion from the bzl::Mul reporter gene. The programming of early sectoring is dominant in crosses with Mutator lines containing diverse reporter alleles. Germinal reversion is biased 5‐ to 10‐fold for events through the pollen compared to the ear. The timing of germinal excision in the tassel is late because somatic excision sectors in the anthers are small; however, 98% of the germinal revertants are concordant. These observations indicate that in the early sectoring line Mu excision usually occurs before the mitotic divisions that separate gametic nuclei and may be restricted to the early stages of microsporogenesis. © 1992 Wiley‐Liss, Inc.
Ferritin gene expression is developmentally regulated and induced by heat shock in sea urchin embryos
Authors: Infante A. A. , Infante D. , Rimland J. 
Published: May 2005

AbstractA 20‐kD protein identified as a subunit of the iron‐binding protein ferritin is present in S. purpuratus and L. pictus sea urchin embryos. The synthesis of the protein is stimulated by an elevation in temperature or by an increase in iron supply. The developmental expression of this protein and its regulation during normal development and upon heat shock was investigated. In L. pictus, ferritin is present in the unfertilized egg and, as determined by Western blot analysis, its concentration remains approximately constant after fertilization up to the gastrulc‐pluteus stage; there is a small transient decrease in the level of the protein in the early blastula at a time coinciding with the first clear indication of its de novo synthesis. Northern blots reveal no cytoplasmic ferritin transcripts in the unfertilized egg, but there occurs a dramatic increase in the RNA level from the late morulaearly blastula stage (12–14 hr) to the mesenchyme blastula‐early gastrula (25–30 hr) stage. This developmentally regulated increase in the constitutive concentration of ferritin RNA is correlatable with the normal onset of synthesis of the protein. The overall degree and nature of induction of ferritin by heat is dependent on the developmental stage: at 10–16 hr postfertilization heat shock elicits an increase in both the concentration of RNA and the synthesis of the protein; in hatched blastula (18 hr) and in later embryos heat shock increases ferritin synthesis, without a corresponding increase in the mRNA level. It appears that different mechanisms operate in the developing sea urchin embryo to regulate the expression of ferritin during normal development and on exposure to heat stress, one dependent on the concentration of ferritin transcripts and another operating at the level of translational control. © 1993Wiley‐Liss, Inc.
Heat shock induces changes in the expression and binding of ubiquitin in senescentDrosophila melanogaster
Authors: Niedzwiecki Aleksandra , Fleming James E. 
Published: May 2005

AbstractWe examined the effect of aging on the expression of ubiquitin RNA and the binding of the ubiquitin polypeptide to proteins following heat shock inDrosophila melanogaster.Heat‐shocked adult flies transcribe two major RNA species‐one of 4.4 kb and one of about 6 kb that hybridize to the polyubiquitin‐encoding probe. Several less abundant RNAs were also observed but the 4.4‐kb band was present as the major RNA species in both stressed and nonstressed flies of both ages. The 6‐kb fragment was more abundant in heat shocked aged flies than in younger flies. The quantitative expression of the polyubiquitin gene increased in proportion to the duration of the heat stress. Moreover, the induction of the polyubiquitin RNA was markedly elevated during aging following heat shock. Hybridization of Northern blots with the monoubiquitin gene probe revealed a band of 0.9 kb that was not significantly affected by heat stress.We also investigated the relationship between the changes in polyubiquitin gene expression and the formation of ubiquitin‐protein complexes in aging heat‐shocked flies. Heat shock to old flies results in a significant increase in the level of proteins immunoprecipitated by anti‐ubiquitin antibodies. In the case of proteins synthesized 2 h before heat shock, most of the ubiquitinated proteins were of high molecular weight. For those proteins synthesized during a 30‐min heat shock and the 2 h following heat shock, two major immunoprecipitated bands were observed: an 80‐kD and a 70‐kD polypeptide. The ubiquitination of a 60 kD protein was also observed in nonstressed flies, but its for mation was drastically reduced following heat shock. For proteins synthesized during and after heat shock from both age groups, the major ubiquitinated polypeptide is 70 kD. In all age groups, more ubiquitin complexes were formed with proteins synthesized before heat shock, than with proteins synthesized either during or after heat shock. This suggests that cellular proteins synthesized at physiological temperatures are more sensitive to heat induced damage than those synthesized during stress. These data support the hypothesis that in aging flies, heat shock induces an unusually high concentration of abnormal proteins which are targeted for degradation by the ubiquitin‐dependent proteolytic system. © 1993Wiley‐Liss, Inc.
Changes in heat shock protein synthesis and heat sensitivity during mouse thymocyte development
Authors: Mosser Dick D. , Duchaine Jean , Bourget Lucie , Martin Luis H. 
Published: May 2005

AbstractHeat shock protein synthesis was examined in mouse thymocytes at three stages of development: early embryonic thymocytes, which are CD4−CD8−, adult thymocytes, which are primarily CD4+CD8+, and mature spleen T cells, which are CD4+CD8− or CD4−CD8+. After either a 41°C or 42°C heat shock, the synthesis of the maior heat‐inducible protein (hsp68) was elevated during the first hour of recovery but then decreased abruptly in thymocytes from adult mice. In contrast, the synthesis of hsp68 continued for up to 4 h after heating embryonic mouse thymocytes or mature spleen T cells. The more rapid termination ofthe heat shock response in the adult thymocytes was not the result of eitherless heat damage or more rapid repair since the recovery of general protein synthesis was more severely delayed in these cells. As well, the double positive CD4+CD8+ cells were more sensitive to hyperthermia than either the double negative CD4−CD8− or single positive CD4+CD8− or CD4−CD8+ cells. Exposure of fetal thymus organ cultures to elevated temperature revealed that the double negative thymocytes were able to survive and differentiate normally following a heat shock treatment that was lethal for the double positive thymocytes. Exposure of thymocytes from adult mice to elevated temperatures induced apoptotic cell death. This was evident by the cleavage of DNA into oligonucleosome‐sized fragments. Quantitation of the extent of DNA fragmentation and the number of apoptotic cells by flow cytometry demonstrated that the extent of apoptotic cell death was related to the severity of the heat stress. Double positive (CD4+CD8+) thymocytes are selected on the basis of their T‐cell antigen receptor (TCR). Most of these cells are negatively selected and die within the thymus by an active process of cell deletion known as apoptosis. Restricting hsp synthesis in response to stress might be essential during developmental processes in which cell maturation is likely to result in death rather than functional differentiation. © 1993Wiley‐Liss, Inc.
Expression of alternative forms of differentiation inhibiting activity (DIA/LIF) during murine embryogenesis and in neonatal and adult tissues
Authors: Robertson Morag , Chambers Ian , Rathjen Peter , Nichols Jennifer , Smith Austin 
Published: May 2005

AbstractDifferentiation inhibiting activity/leukaemia inhibitory factor (DIA/LIF) is a pleiotropic cytokine which has been implicated in a variety of developmental and physiological processes in mammals due to its broad range of biological activities in vitro. A role in very early development is suggested by the requirement for DIA/ LIF to support the self‐renewal of cultured embryonic stem (ES) cells. Other data point to potential roles in the establishment and maintenance of primordial germ cells, in osteogenesis and in haematopoiesis, and possibly in neuronal specification. DIA/LIF may also act as a mediator of the hepatic acute phase response. In the present study the expression of DIA/LIF transcripts during murine development and in adult mice has been determined using a highly sensitive ribonuclease protection analysis. In contrast to previous reports, it is apparentthat DIA/LIF transcripts are present at low levels in many adult mouse tissues. Higher levels of expression are observed in skin, lung, intestine, and uterus. Elevated amounts of mRNA are also found in certain foetal tissues during late gestation and neonatally. In earlier embryogenesis, however, DIA/LIF mRNA is produced primarily in extraembryonic tissues. The alternative transcripts which produce either soluble or matrix‐associated DIA/LIF exhibit overlapping but non‐identical patterns of expression, consistent with the proposition that the two isoforms may have distinct biological functions. These findings are suggestive of widespread roles for DIA/LIF in vivo and are discussed in the light of available data on the phenotype of homozygous DIA/LIF‐deficient mice. © 1993Wiley‐Liss, Inc.
Differential induction of regulatory genes during mesoderm formation in Xenopus laevis embryos
Authors: Tadano Takafumi , Otani Hiroki , Taira Masanori , Dawid Igor B. 
Published: May 2005

AbstractMesoderm development in Xenopus laevis depends on inductive cell interactions mediated by diffusible molecules. The mesoderm inducer activin is capable of redirecting the development of animal explants both morphologically and biochemically. We have studied the induction of four regulatory genes, Mix. 1, goosecoid (gsc), Xlim‐1 and Xbra in such explants by activin, and the influence of other factors on this induction. Activin induction of gsc is strongly enhanced by dorsalization of the embryo by LiCl, while expression of the other genes is only slightly enhanced. The protein synthesis inhibitor cycloheximide (CHX) inhibits the activin‐dependent induction of Xbra partially, while induction of Mix. 1 and Xlim‐ 1 is essentially unaffected. In contrast, gsc shows strong superinduction in the presence of activin and CHX, and can be induced in animal explants by CHX alone. Induction and superinduction by CHX have previously been observed for immediate early genes in a variety of systems, notably for the activation of c‐fos expression by serum stimulation, but have not been reported in early amphibian embryos. © 1993Wiley‐Liss, Inc.
Attenuation of white gene expression in transgenic Drosophila melanogaster: Possible role of a catalytic antisense RNA
Authors: Heinrich Jörg‐Christian , Tabler Martin , Louis Christos 
Published: May 2005

AbstractWe have transformed Drosophila melanogaster with a DNA construct encoding a catalytic antisense RNA directed against the primary white gene RNA transcript. Total RNA isolated from transformed flies was shown to catalyze the specific cleavage of in vitro transcribed substrate RNA, indicating the expression of a functional ribozyme. Moreover, transgenic lines carrying homozygous copies of this construct depict a further clear‐cut reduction in eye pigmentation when present in a genetic background that has a priori reduced levels of white gene expression. © 1993Wiley‐Liss, Inc.
Regulation of the Dictyostelium glycogen phosphorylase 2 gene by cyclic AMP
Authors: Sucic Joseph F. , Selmin Ornella , Rutherford Charles L. 
Published: May 2005

AbstractA crucial developmental event in the cellular slime mold, Dictyostelium discoideum, is glycogen degradation. The enzyme that catalyzes this degradation, glycogen phosphorylase 2 (gp‐2), is developmentally regulated and cAMP appears to be involved in this regulation. We have examined several aspects of the cAMP regulation of gp‐2. We show that addition of exogenous cAMP to aggregation competent amoebae induced the appearance of gp‐2 mRNA. The induction of gp‐2 mRNA occurred within 1 and 1.5 h after the initial exposure to cAMP. Exposure to exogenous cAMP concentrations as low as 1.0 μM could induce gp‐2 mRNA. We also examined the molecular mechanism through which cAMP induction of gp‐2 occurs. Induction of gp‐2 appears to result from a mechanism that does not require intracellular cAMP signaling, and may occur directly through a cAMP binding protein without the requirement of any intracellular signalling. We also examined the promoter region of the gp‐2 gene for cis‐acting elements that are involved in the cAMP regulation of gp‐2. A series of deletions of the promoter were fused to a luciferase reporter gene and then analyzed for cAMP responsiveness. The results indicated that a region from ‐258 nucleotides to the transcriptional start site is sufficient for essentially full activity and appears to carry all necessary cis‐acting sites for cAMP induction. Further deletion of 58 nucleotides from the 5′ end, results in fivefold less activity in the presence of cAMP. Deletion of the next 104 nucleotides eliminates the cAMP response entirely. © 1993Wiley‐Liss, Inc.
Tissue‐specific regulation by ecdysone: Distinct patterns of Eip28/29 expression are controlled by different ecdysone response elements
Authors: Andres Andrew J. , Cherbas Peter 
Published: May 2005

AbstractThe Eip28/29 gene of Drosophila is an example of a tissue‐ and stage‐specific ecdysone‐responsive gene. Its diverse patterns of expression during the third larval instar and a synopsis of those patterns in terms of expression groups have been reported previously. Here we have studied the expression (in transgenic flies) of reporter genes controlled by Eip28/29‐derived flanking DNA. During the middle and late third instar, most tissues exhibit normal expression patterns when controlled by one of two classes of regulatory sequences. Class A sequences include only 657 Np of 5′ flanking DNA from Eip28/29. Class B sequences include an extended 3′ flanking region and a minimal (≤93 Np) 5′ flanking region. The class B sequences include all those elements known to be important for ecdvsone induction in cultured cells. They are sufficient to direct the normal premetamorphic induction of Eip28/29 in the lymph glands, hemocytes, proventriculus, and Malpighian tubules. This is consistent with our suggestion that Kc cells are derived from embryonic hematopoietic cells. It is remarkable that the epidermis requires only class A sequences. These are sufficient to up‐regulate expression at medinstar and to down‐regulate expression at metamorphosis. It follows that the epidermis uses EcREs distinct from those that function in Kc cells. It is possible that the Upstream EcRE, which is nearly silent in Kc cells, is active in the epidermis. © 1994 Wiley‐Liss, Inc.
Screen for enhancers of Polycomb and Polycomblike in Drosophila melanogaster
Authors: Landecker Hannah L. , Sinclair Donald A. R. , Brock Hugh W. 
Published: May 2005

AbstractThere are 11 Polycomb group genes known in Drosophila. These genes are negative regulators of homeotic gene expression, and may act by modifying chromatin structure. It is not clear how many members of the Polycomb group of genes exist. Many were discovered because of their homeotic phenotypes, or because they enhance homeotic mutations. Systematic screens for enhancers of Polycomb have identified previously known members of the Polycomb group. In an attempt to discover cytological locations of new Polycomb group genes, we crossed deletions uncovering about 20% of the genome to Polycomb‐like and Polycomb and scored for enhancement of the extra sex combs phenotype. Haploidy for four regions, 36F7‐37A, 43E18; 44B5‐9, 70C2‐6, and 70C6‐15; 70D enhanced the extra sex comb phenotype associated with strong Polycomb group mutations. These regions have homeotic phenotypes either as homozygous embryos or heterozy‐gous adults, or both. We also show that spalt enhances Polycomb group mutations. These results are discussed with respect to previous estimates of Polycomb group gene number. © 1994 Wiley‐Liss, Inc.
Developmental arrest of fertilized eggs from the B6.YDOM sex‐reversed female mouse
Authors: Merchant‐Larios Horacio , Clarke Hugh J. , Taketo Teruko 
Published: May 2005

AbstractWhen the Y chromosome of a Mus musculus domesticus mouse strain is placed onto the C57BL/6J (B6) inbred background, the XY progeny develop ovaries or ovotestes but never normal testes during fetal life. While some of the hermaphroditic males become fertile, none of the XY females produces litters. Here, we examined the fertility and development of oocytes derived from the XY female mouse. With or without preceding injection of gonadotropins, female mice were mated with normal B6 males, and their embryos were recovered at various developmental stages. In vitro fertilization was performed with the eggs recovered from the oviduct after treatment with go‐nadotropins. Development of embryos was examined by both light and electron microscopy. The results indicate that the oocytes released from the B6.YDOM ovary were efficiently fertilized and often initiated the first cell cleavage, but all embryos died during early preimplantation periods. Even when oocytes were fertilized in vitro, minimizing their exposure to the XY oviduct/uterus environment, most embryos died at the 1‐ or 2‐cell stage. A few exceptional embryos reached the 4‐ or 8‐cell stage, but abnormalities were evident in both nuclear and cytoplasmic structures of all embryos. After cleavage, neighbouring blastomeres were only loosely associated, and microvilli were abundant at the intercellular interfaces. We postulate that oocytes of the B.6.YDOM female mouse become defective during XY ovarian differentiation, and, hence, fail to proceed through normal embryonic development. © 1994 Wiley‐Liss, Inc.
Epigenetics and the maintenance of gene activity states in Caenorhabditis elegans
Authors: Hodgkin Jonathan 
Published: May 2005

AbstractThe nematode Caenorhabditis elegans has been the subject of many detailed investigations in developmental biology. Molecular analyses have failed to detect covalent alterations to DNA, such as methylation or rearrangement, during development of C. elegans. Genetic experiments indicate that imprinting of gamete genomes does not occur to any significant extent. The maintenance of gene activity states in this organism may depend predominantly on regulatory gene circuitry. Some possible examples of maintenance circuits are discussed. © 1994 Wiley‐Liss, Inc.
Expression of an X‐linked HMG‐lacZ transgene in mouse embryos: Implication of chromosomal imprinting and lineage‐specific X‐chromosome activity
Authors: Tam Patrick P. L. , Williams Elizabeth A. , Tan Seong‐Seng 
Published: May 2005

AbstractX‐chromosome activity in female mouse embryos was studied at the cellular level using an X‐linked lacZ transgene which encodes β‐galactosidase (β‐Gal). Translation of maternal RNA in oocytes is seen as β‐Gal activity that persists into early cleavage‐stages. Zygotic transcription of the transgene from the maternal X chromosome (Xm) is first found at about the 8‐cell stage. By contrast, expression of the lacZ transgene on the paternal X chromosome (Xp) is not seen until later at the 16‐32‐cell stage. Preferential inactivation of Xp occurs in the mural trophectoderm, the primitive endoderm, and derivatives of the polar trophectoderm, but a small number of cells in these lineages may still retain an active paternal X chromosome. X inactivation begins at 3.5 days in the inner cell mass but contrary to previous findings the process is not completed in the embryonic ectoderm by 5.5 to 6.0 days. Regional variation in β‐Gal activity is also observed in the embryonic ectoderm during gastrulation which may be related to the specification of cell fates. Random inactivation of Xp and Xm ensues in all somatic tissues but the process is completed at different times in different tissues. The slower progression of X inactivation in tissues such as the notochord, the heart, and the embryonic gut is primarily due to the persistent maintenance of two active X chromosomes in a significant fraction of cells in these tissues. Recent findings on the methylation of endogenous X‐linked genes suggest that the prolonged expression of β‐Gal might also be due to the different rate of spreading of inactivation along the X chromosome to the lacZ transgene locus in different tissues. © 1994 Wiley‐Liss, Inc.