bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sex‐, tissue‐, and stage‐specific expression of a vitelline membrane protein gene from region 32 of the second chromosome of Drosophila melanogaster
Authors: Gigliotti S. , Graziani F. , De Ponti L. , Rafti F. , Manzi A. , Lavorgna G. , Gargiulo G. , Malva C. 
Published: May 2005

AbstractThis study isolated cDNA clones from egg‐chamber and adult female Drosophila cDNA libraries using as probe a DNA fragment from a 200‐kb “chromosome walk” in region 32E of the second chromosome of D. melanogaster. The present authors believe that these clones correspond to a new vitelline membrane protein (VMP) gene because (1) cDNA clones in Northern blots identify a transcript expressed in a tissue‐ and stage‐specific manner: stage 10 egg‐chambers; (2) the sequence of cDNAs and of the genomic subclone shows homology with the other VMP genes that have been identified to date; (3) the amino acid composition of the translational product has the high content of proline and alanine characteristic of VMPs. Two aspects emerging from this study are worth stressing: (1) the presence of a hydrophobic domain that is highly conserved in all the VMP genes; and (2) the particularly narrow period of expression of the isolated gene, which could be related to the mechanism of vitelline membrane assembly.
The role of polyfusomes in generating branched chains of cystocytes during Drosophila oogenesis
Authors: Storto Patrick D. , King Robert C. 
Published: May 2005

AbstractThree‐dimensional models were constructed utilizing the information gained from electron micrographs of serial sections of two clones of cystocytes undergoing their terminal divisions. In each clone a polyfusome connected all eight cystocytes together. Each of the spindles was oriented so that one pole touched the polyfusomes, while the other pointed away from it. This positioning of spindles ensures that one cell of each dividing pair retains all previously formed canals, while the other receives none. The two cells that eventually come to contain the maximum number of canals and fusomal material are the ones that differentiate as pro‐oocytes, while the others become nurse cells. The orientation of each spindle suggests that the polyfusome formed at one division determines the placement of the cytoskeletal fibers that anchor the spindles formed at the next division. There is a centripetal gathering together of new canals following each cycle of cystocyte division, which is thought to result from the subsequent contraction of the polyfusomal system. Females homozygous for the otu1 mutation are characterized by ovarian tumors, which result when germarial cystocytes undergo supernumerary divisions and fail to differentiate into either nurse cells or oocytes. An analysis of electron micrographs taken of serially sectioned, mutant germaria showed that most germ cells were single or belonged to clusters of two or three interconnected cells. Therefore otu1 cystocytes are unable to undergo a sustained series of arrested cleavages. These cystocytes contain fusomal material that shows ultrastructural differences from normal polyfusomes. We conclude: (1) that a normal polyfusomal system is a necessary prerequisite for the production of a branched chain of cystocytes and for their subsequent differentiation into pro‐oocytes and nurse cells; and (2) that a product encoded by the otu+ gene is essential for the construction of a functional polyfusome.
Regulated expression of genes encoding soybean β‐conglycinins in transgenic plants
Authors: Chen Zhang‐Liang , Naito Satoshi , Nakamura Ikuo , Beachy Roger N. 
Published: May 2005

Abstractβ‐conglycinin, an abundant storage protein in soybean seeds, is comprised of three subunits: α', α, and β. Expression of genes encoding these subunits is tissue‐specific and temporally regulated in soybean plants. Both the α'‐and β‐subunit genes have been isolated and fully or partially characterized by DNA sequence analysis. Each has been transferred to transgenic plants and was found to be expressed in petunia and tobacco plants in a regulated manner as in soybean plants. Both the α'‐ and β‐subunit proteins were accumulated only in transgenic seeds during mid‐to‐late stages of seed development and assembled into multimeric forms with sedimentation coefficients of 7S and 9S. The α'‐ and β‐subunit genes were also introduced on the same plasmid into transgenic plants. When the promoters of the two genes were proximal to each other, there was an increase in the expression of the β‐subunit gene, suggesting that there is a strong cis‐acting sequence in the α'‐gene (promoter) that can affect expression of the α‐subunit gene.A series of deletion mutants was constructed in the α'‐gene promoter, and each was introduced into petunia plants. The DNA sequence approximately 250 bp upstream of the transcriptional initiation site contains sufficient regulatory information for expression of the α'‐subunit gene. The sequence about 200 bp upstream contains four 6‐bp repeats A (AGCCCA) that may play an important role in regulating expression of the α'‐gene. The function of this DNA sequence (‐78 to ‐257) was tested in a chimeric gene construct containing the CaMV 35S promoter, the CAT coding sequence, and the 3′ noncoding region of the α'‐gene. A dramatic enhancement of the CAT gene expression (at least 40‐fold) resulted when this DNA sequence was inserted into the 35S promoter at a position 90 bp upstream of the transcription start site, regardless of the orientation of the insert. There was a two‐ to threefold enhancement when the element was placed 3′ to the CAT coding region and no enhancement when placed downstream of the 3′ noncoding region. The enhancement was observed only in seeds during mid‐to‐late stages of seed development. This indicates that the 170‐bp DNA sequence can function as a strong cis‐acting element that controls seed‐specific and temporally regulated gene expression. This element is defined as a seed‐specific and developmentally regulated element (SDRE).
Molecular genetics of transformer, a genetic switch controlling sexual differentiation in Drosophila
Authors: Belote John M. , McKeown Michael , Boggs Russell T. , Ohkawa Risa , Sosnowski Barbara A. 
Published: May 2005

AbstractThe transformer gene is one of a set of regulatory genes that form the hierarchy controlling all aspects of somatic sexual differentiation in Drosophila melanogaster. The gene transformer occupies an intermediate position in this hierarchy. Analysis of this gene has allowed us to determine the mechanism by which it is regulated in a sex‐specific manner and to examine the way in which the regulatory hierarchy is organized. The female‐specific expression of the tra gene, previously inferred from genetic observations, is bused on sex‐specific alternative splicing of tra pre‐mRNA and is not the result of sex‐specific transcriptional activation. The female‐specific RNA produced by this alternative splicing is the functional mediator of tra activity. Multiple genetic, molecular, and transformation experiments show that female‐specific activation of genes or gene products occurs in the order Sex lethal > transformer > transformer‐2 > doublesex · intersex > female differentiation. The results do not distinguish the level at which transformer might regulate the downstream gene transformer‐2. Neither transformer nor any of the downstream genes feedback on, or participate in, alternative splicing of transformer RNA. The mechanism by which Sex lethal regulates transformer splicing appears to be a repression of the use of one of a pair of splice acceptor sites.
Effects of juvenile hormone on the ecdysone response of Drosophila Kc cells
Authors: Cherbas Lucy , Koehler M. Macy D. , Cherbas Peter 
Published: May 2005

AbstractDrosophila Kc cells are ecdysone‐responsive: hormone treatment leads rapidly to increased synthesis of several ecdysone‐inducible polypeptides (EIPs) and to commitment to eventual proliferative arrest. Later, the treated cells undergo morphological transformation, cease to proliferate, and develop new enzymatic activities, notably, acetylcholineslerase (AChE) activity. These responses have proven useful as models for studying ecdysone action. Here we report the sensitivity of Kc cells to another important insect developmental regulator—juvenile hormone (JH). We find that JH inhibits some, but not all, aspects of the ecdysone response. When Kc cells are treated with ecdysone in the presence of either natural JHs or synthetic analogues, the morphological and proliferative responses are inhibited and AChE induction is blocked. Most striking is that JHs protect the cells from the rapid proliferative commitment induced by ecdysone alone. The JH effects exhibit reasonable dose‐response curves with half‐maximal responses occurring at very low JH concentrations. Nonetheless, even at high JH concentrations the inhibitory effects are incomplete. It is interesting that EIP induction appears to be refractory to JH. It seems clear that JH is not simply a generalized inhibitor of ecdysone‐induced responses.
Regulatory elements and interactions in the Drosophila 68C glue gene cluster
Authors: Martin Marianne , Mettling Clément , Giangrande Angela , Ruiz Claude , Richards Geoff 
Published: May 2005

AbstractWe reviewed studies on the developmental regulation of the 68C glue gene cluster of Drosophila melanogaster. Extensive transformation analyses of Sgs‐3 have shown that four regions necessary for normal expression can be distinguished. The first ( + 10 to ‐50) contains the transcription start site and TATA motif. This region can be replaced functionally by corresponding sequences from the hsp70 gene, but it is sensitive to point mutations in the TATA sequence. The second region (‐50 to ‐98) contains more than one upstream sequence that, in combination with the other elements, leads to stage and tissue‐specific expression. The third region (centered at ‐600) contains an element that enhances transcript levels some 20‐fold. The final region (between ‐1.65 and ‐2.35 kb) contains elements having modest (twofold to threefold) effects on expression, one of which is contained in the coding sequences of Sgs‐7, a second member of the cluster.
Regulation of larval cuticle protein gene expression in Drosophila melanogaster
Authors: Kimbrell Deborah A. , Tojo Shinichiro J. , Alexander Sherry , Brown Elizabeth E. , Tobin Sara L. , Fristrom James W. 
Published: May 2005

AbstractGenes that encode 3rd instar larval cuticle proteins (LCP's) of Drosophila melanogaster are located in at least two chromosomal sites. The genes encoding four of the five predominant LCP's are located in a cluster at the chromosomal region 44D. They are organized in pairs that are transcribed divergently, and expressed with different timing during the third larval instar. Towards understanding the basis of gene regulation within the 44D cluster, we have analyzed genetic variants, including the 2‐3 variant, which has an insertion of a copia‐like transposable element, H.M.S. Beagle, within the 44D cluster. The Beagle element appears to inactivate the LCP‐3 gene by inserting into its TATA box, but also may cause the precocious expression of two other LCP genes, LCP‐1 and LCP‐f2, in the cluster. The long terminal repeat (LTR) of the Beagle element apparently contains a sequence, perhaps an enhancer‐like element, which causes altered expression of these genes. We have also investigated the cis‐regulatory elements involved in expression of the LCP‐2 gene in wild‐type larvae. We have identified two upstream regions that may contain separate cisregulatory elements. The region between ‐252 bp and ‐515 bp may be essential for any expression of LCP‐2. Additionally, the region between ‐515 bp and ‐795 bp appears to be required for the normal level of expression of the LCP‐2 gene.
The gypsy retrotransposon of Drosophila melanogaster: Mechanisms of mutagenesis and interaction with the suppressor of Hairy‐wing locus
Authors: Harrison Douglas A. , Geyer Pamela K. , Spana Carl , Corces Victor G. 
Published: May 2005

AbstractWe have used the yellow gene of Drosophila melanogaster as a model system in which to study the molecular mechanisms by which the gypsy retrotransposon causes mutant phenotypes that can be reversed by nonalleiic mutations at the suppressor of Hairy‐wing locus. This gene encodes a 109,000 dalton protein that contains an acidic domain and 12 copies of the Zn finger motif, which are characteristic of some transcription factors and DNA binding proteins. The suppressible y2 allele is caused by the insertion of the gypsy element at ‐700 bp from the start of transcription of the Yellow gene, resulting in a phenotype characterized by mouth parts and denticle belts in the larvae, and by bristles in the adults, that show wildtype coloration, but mutant wings and body cuticle in the adult flies. This phenotype is the result of the interaction of gypsy sequences homologous to mammalian enhancers with tissue‐specific yellow transcriptional regulatory elements located upstream from the gypsy insertion site and responsible for the expression of the yellow gene in the mutated tissues. This interaction is dependent on the binding of the su(Hw) protein to the specific gypsy sequences involved in the induction of the mutant phenotype.
Genetic interactions of the Suppressor 2 of zeste region genes
Authors: Adler Paul N. , Charlton Jeannette , Brunk Brian 
Published: May 2005

AbstractA wide variety of gain of function mutations have been induced in the Posterior Sex Comb (Psc)—Aristapedioid (Arp)—Suppressor 2 of zests(Su(z)2) region of the second chromosome of Drosophila. This region contains at least three apparently related genes, two of which we have been studying. Psc1 has previously been used to identify Psc as a Pc group gene; however, it is a complex mutation with both gain and loss of function character. We report here that the Pc group character of Psc is not due to a gain of function and presumably reflects the function of the wild‐type gene. We also provide evidence for a maternal function for Psc, as well as the neighboring Su(z)2 gene.Su(z)2 does not appear to be a Pc group gene as it does not act in a synergistic fashion with other PC group genes in promoting posteriorly directed transformations. However, we have found that mutations in Su(z)2 do interact in a variety of interesting ways with mutations in Pc group genes.
Molecular and developmental genetics of the Punch locus, a pterin biosynthesis gene in Drosophila melanogaster
Authors: O'Donnell Janis M. , McLean Janna R. , Reynolds Elaine R. 
Published: May 2005

AbstractPunch(Pu), the gene encoding the pterin biosynthetic enzyme GTP cyclohydrolase in Drosophila, is a complex locus. Mutations fall into several complementation classes that correspond to classes of mutants with distinct morphological and protein phenotypes. Two of these classes are developmentally specific, with mutants in each having defects in discrete subsets of the known functions of the locus. Defined functions of the locus include a role in embryonic nuclear divisions using initially a maternal Pu product, the synthesis of pterin cofactors that are required for cat‐echolamine biosynthesis beginning in late embryogenesis, and the production of pterin‐screening pigments in the developing adult eye. Mutant phenotypes include an interruption in synchronous nuclear divisions in precellular blasto‐derm embryos, a segment pattern phenotype in late embryos, failure to pigment and cross‐link embryonic cuticular structures and failure to synthesize red eye pigments. Molecular analysis reveals that the locus is large, a minimum of 29 kb as defined by Southern mapping of Pu mutants. This region is transcriptionally extremely active, encoding at least 16 developmentally regulated transcripts. One transcript has been shown to be responsible for the production of the adult eye GTP cyclohydrolase on the basis of developmental profile, location with respect to the mapping of eye‐specific Pu mutants, absence in eye‐specific mutants, and hybrid‐selection in vitro translation experiments. Several other transcripts are candidates for Pu vital functions, as suggested by their pattern of expression and their derivation from regions to which lethal Pu mutations map.
Histochemical analysis of extracellular matrix material in embryonic trisomy 1 mouse eye
Authors: Smith B. S. 
Published: May 2005

AbstractTrisomic animals produced from mice doubly heterozygous for Robertsonian translocation chromosomes [Rb(1.3)/Rb(1.10)] consistently show eye defects (e.g., aphakia, micro‐phakia, and retention of lens stalk). To determine if changes in distribution or composition of extracellular matrix material may be a factor in development of these defects, eye structures of tnsomy (ts) 1 embryos and normal littermates were studied his‐tochemically using the following methods: Alcian blue 8GX, pH 2.5; periodic acid‐Schiff (PAS), Alcian blue/PAS combined; high‐iron diamine (HID); and HID/Alcian blue combined. Eye development was divided into stages to account for the known delay in ts 1 mouse development.Differences were found in staining patterns as early as stage 1. In later stages, the most consistent difference was an increased period of contact between lens and optic cup due to retardation of interface matrix dissolution between these rudiments in ts 1 embryos. Eyes in which this occurred had abnormally shaped lenses. Overall, the ts 1 optic cup appeared to have fewer staining abnormalities and dysmorphology than did the lens or interface matrix.Triplication of a chromosome may indirectly alter temporal and spatial organization of extracellular matrix through action on cells responsible for the production of this material. Possible mechanisms of action are discussed.
Compaction‐defective embryonal carcinoma cell variants
Authors: Littlefield John W. 
Published: May 2005

AbstractCompaction of the morula is a prerequisite for subsequent differentiation of the mouse embryo. Analogous differentiation follows compaction in aggregates of several embryonal carcinoma cell lines. This report describes the isolation of two compaction‐defective variants from the H6 embryonal carcinoma cell line. These were isolated directly as clonal compaction‐defective aggregates in medium containing 1.3% methylcel‐lulose. They were obtained following chemical mutagenesis, since spontaneous variants were not seen. Compaction‐defective variants of the F9 ECC line or the ES‐D3 embryonic stem cell line could not be obtained. One of the H6 compaction‐defective variants appeared to be dominant when hybridized to its parental line, while the other appeared to be recessive.
5‐Azacytidine‐induced tumorous transformation and DNA hypomethylation in Nicotiana tissue cultures
Authors: Durante Mauro , Cecchini Edi , Natali Lucia , Citti Lorenzo , Geri Chiara , Parenti Roberto , Ronchi Vittoria Nuti 
Published: May 2005

AbstractThe phenomenon of habituotion is considered in plant tissue cultures to be a real process of chemical tumorogenesis: the cultures acquire the capacity of autonomous growth in a hormone‐free medium under the influence of a variety of chemical and physical agents. Treatments with 5‐azacytidine (AzaC) of in vitro cultured cells of the Nicotiana glauca × N. langsdorffii nontumorous hybrid (NNT)during the culture cycle led to the induction of a habituated phenotype. The repetitive DNA sequences showed a significant lower level of endogenous methylation in the treated cells in comparison with the normal ones. It is worth noting that it was impossible until now to habituate this strain by conventional methods and that the treatments were effective only in the first 5 days of subculturing; various evidence (cytological and biochemical) pointed out a phenomenon of DNA amplification, occurring in the same period. Moreover, analysis of DNA from control and treated cells shows the induction of variations in the endogenous methylation pattern by AzaC in a critical period of cell culture. These results suggest that demethylation can act as a switch from hormone‐dependent to autonomous proliferation by activation of genes coding for or regulating the synthesis of growth factors.
Differential expression of the maize catalase genes during kernel development: The role of steady‐state mRNA levels
Authors: Wadsworth Gregory J. , Scandalios John G. 
Published: May 2005

AbstractIn maize three isozymic forms of catalase, CAT‐1, CAT‐2, and CAT‐3 are encoded by three distinct and unlinked structural genes (Catl, Cat2, and Cat3). Catalase activity profiles and zymogram analysis were used to examine the spatial and temporal expression of the three genes during kernel maturation. Three developmental stages of catalase expression were observed in the growing kernel. During stage 1 (6‐12 days after pollination), both Catl and Cat3 were expressed; during stage 2 (15‐18 days after pollination) only Cat1 expression was observed; and during stage 3 (21‐30 days after pollination), Cat1 and Cat2 were expressed. The major constituent tissues of the kernel were examined to determine their contribution to total kernel catalase expression. Each of the tissues was found to have a unique pattern of catalase gene expression. RNA blot analysis, using catalase gene‐specific nucleic acid probes, suggests that the differential expression of the three catalase genes observed in the kernel is regulated by controlling the distribution of steady‐state mRNA species for the three genes.
Connexin32, a gap junction protein, is a persistent oogenetic product through preimplantation development of the mouse
Authors: Barron Douglas J. , Valdimarsson Gunnar , Paul David L. , Kidder Gerald M. 
Published: May 2005

AbstractGap junctions appear de novo during compaction in the eight‐cell stage of mouse development. This is a critical event in the life of the embryo, because gap junctional intercellular communication is an essential requirement for maintaining compaction and, hence, for development of the blastocyst. Recently, a family of genes encoding gap junction proteins (connexins) has been identified and cloned, and we have taken advantage of the availability of antibodies and cDNA probes to investigate the expression of these genes in early development. We found that a protein with antigenic and size similarity to the “liver” gap junction protein, connexin32, is present throughout preimplantation development from the zygote through the late morula. Connexin32 mRNA, however, could not be detected in any preimplantation stage. This, and the presence of connexin32 in zygotes before activation of embryonic transcription, leads us to conclude that this protein is inherited as an oogenetic product that persists well beyond the transition from the oogenetic to embryonic program of gene expression. Furthermore, we found that mRNA for another gap junction protein, connexin43, is fairly abundant in preimplantation embryos. We conclude that it is more likely connexin43, and not connexin32, that is used to assemble new connexons as the level of intercellular coupling increases after compaction.