bluuebunny/crossref_metadata_2025 huggingface dataset:
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

We 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

A 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

Punch(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

Trisomic 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

Compaction 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

The 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

In 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

Gap 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.
Regulation of catalase‐specific mRNA and its processing during development in mice
Authors: El‐Hage Samar , Singh Shiva M.
Published: May 2005

This study deals with the pattern of developmental expression of the catalase gene in mice. We have used a mouse catalase 2 kb cDNA (pMCT‐1) and its 1.4 kb 5′ fragment as probes to characterize the transcripts during embryonic development and differentiation. Total RNA was isolated from 8 days postconceptus (p.c.) whole embryos and from livers and carcasses of 13, 15, and 18 day p.c. embryos as well as from the livers of newborn and adult mice of the S.W. strain. The RNA was applied on slot blots, and run on agarose gels to generate northern blots. Blots were hybridized with the 32P‐labeled cDNA probe under different stringency conditions. Autoradiograms were scanned with a densitometer to quantify relative hybridization signals of RNA samples obtained from two or three individual mice representing each stage of development.

The catalase transcript is detectable as early as 8 days p.c. with the beginning of somite formation. At this stage, it is primarily in the form of a 12.2 kb transcript. One additional band (2.4 kb) is also apparent at this stage although at a very low intensity. The intensity of the two bands increases with development, particularly during 13‐18 days p.c. in liver and carcass. The 2.4 kb RNA band increases sharply from day 8 through 13, 15, and 18 days p.c. and is confined primarily to the liver. Interestingly, only the 2.4 kb RNA band is seen at and after birth. The 2.4 kb RNA is the known mature message of the catalase gene in mice. The presence of large catalase‐specific RNA species (seen during development in utero only) is interpreted as the primary transcript of this gene. The complete and efficient processing of this primary transcript takes place only after birth and primarily in the liver, which may be related to the physiological role of this enzyme in oxygen metabolism, particularly stressful superoxides, expected with independent respiration. At a lower stringency wash of the northern blots, a 9.5 kb RNA was seen during a narrow window of in utero development. This 9.5 kb band may represent an uncharacterized catalase‐related gene with a possible role in development and differentiation.
Liver‐specific and high‐level expression of human serum amyloid P component gene in transgenic mice
Authors: Iwanaga Tomohisa , Wakasugi Shoji , Inomoto Takeaki , Uehira Masahiro , Ohnishi Shuji , Nishiguchi Seiji , Araki Kimi , Uno Masashi , Miyazaki Jun‐Ichi , Maeda Shuichiro , Shimada Kazunori , Yamamura Ken‐Ichi
Published: May 2005

To analyze the regulation of human serum amyloid P component (SAP) gene expression, we have produced seven transgenic mice. The 3.3 kb human SAP genes containing about 0.8 kb of 5′ and 1.5 kb of 3′ flanking region were injected into fertilized eggs of C57BL/6 mice. In five of the seven transgenic mice, human SAP was detected in the sera and serum concentrations were higher than that of human serum in three lines. The human SAP gene was expressed only in the liver. Amounts of human mRNA in the liver and serum concentrations of human SAP were roughly proportional to the copy number of the integrated gene. Human SAP production lowered the serum levels of mouse endogenous SAP. With the intraperitoneal administration of lipopolysaccharide, the mRNA levels in the liver and serum levels of mouse SAP increased several‐fold in both the control and transgenic mice. On the other hand, neither the mRNA nor the serum levels of human SAP increased significantly.
Temporal and tissue‐specific expression of myosin heavy chain isoforms in developing and adult avian muscle
Authors: Merrifield Peter A. , Sutherland William M. , Litvin Judith , Konigsberg Irwin R.
Published: May 2005

We have raised monoclonal antibodies (Mabs) to myosin heavy chain isoforms (MHCs) that have specific patterns of temporal expression during the development of quail pectoral muscle and that are expressed in very restricted, tissue‐specific patterns in adult birds. We find that an early embryonic, a perinatal, and an adult‐specific, fast myosin heavy chain a.e co‐expressed at different levels in the pectoral muscle of 8‐12 day quail embryos. The early embryonic MHC disappears from the pectoral muscle at approximately 14 days in ovo, whereas the perinatal MHC persists until 26 days post‐hatching. The adult‐specific MHC accumulates preferentially and eventually completely replaces the other isoforms. These Mabs cross‐react with the homologous isoforms of the chick and detect a similar pattern of MHC expression in the pectoral muscle of developing chicks. Although the early embryonic and perinatal MHC isoforms recognized by our Mabs are expressed in the pectoral muscle only during distinct developmental stages, our Mabs also recognize MHC isoforms present in the heart and extraocular muscle of adult quail. Immunofingerprinting using Staphylococcus aureus protease V8 suggests that the early embryonic and perinatal MHC isoforms that we see are strongly homologous with the adult ventricular and extraocular muscle isoforms, respectively. These observations suggest that at least three distinct MHC isoforms, which are normally expressed in adult muscles, are co‐expressed during the early development of the pectoral muscle in birds. In this respect, the pattern of expression of the MHCs recognized by our Mabs in developing, fast muscle is very similar to the patterns described for other muscle contractile proteins.
Tissue‐ and developmental stage‐specific expression of the rat ornithine carbamoyltransferase gene in transgenic mice
Authors: Murakami Takashi , Takiguchi Masaki , Inomoto Takeaki , Yamamura Ken‐Ichi , Mori Masataka
Published: May 2005

Rat ornithine carbamoyltransferase (OCT; EC 2.1.3.3) is encoded by a large gene of 75 kilobases. Expression of this gene is restricted to the liver and small intestine, and there is an increase in expression late in gestation. The recombinant gene carrying 1.3 kilobases of the 5′ flanking region of the gene fused to the rat OCT cDNA was microinjected into fertilized eggs, and 17 transgenic mice were produced. Expression in the liver of the transgene was detected in three mice. In these mice, the transgene expression was observed exclusively in the liver and small intestine. Expression of the transgene in the intestine was comparable to that of the endogenous mouse OCT gene, whereas expression in the liver was much lower than that of the endogenous gene. The developmental pattern of expression of the transgene was similar to that of the endogenous gene. Therefore, the 5′ flanking sequence of the rat OCT gene seems to be sufficient for the developmental and tissue‐specific expression of the gene. An explanation for low expression in the liver remains the subject of ongoing study.
Tissue‐Specific effects of maize bronze gene promoter mutations induced by Ds1 insertion and excision
Authors: Sullivan Thomas D. , Schiefelbein John W. , Nelson Oliver E.
Published: May 2005

Bz‐wm is an allele of the Bz locus of maize isolated by McClintock (1962) as a derivative of bz‐m2 It contains a Ds1 insertion 63 bp upstream of the start of transcription and a 3 bp insertion in the coding region at the site of the Ac element that was present in bz‐m2. Bz‐wm produces, in the aleurone layer of the endosperm, low amounts (∼1% of wild‐type) of a Bz‐gene encoded UDP‐glucose: flavoid 3‐0‐glucosyltransferase (UFGT) polypeptide with altered thermal stability. Three phenotypically wild‐type derivatives, Bz' (wm)‐1, Bz' (wm)‐2 and Bz' (wm)‐3, were isolated in the presence of Ac and shown to have excised the Ds1 element but not fully restored UFGT activity in endosperm assays. In the studies reported here, we have further analyzed these Bz' derivatives of Bz‐wm by determining the DNA sequences left behind on Ds1 excision, and by measuring the amount of UFGT activity and/or Bz mRNA conditioned by Bz‐wm and the Bz' derivatives in different tissues. The data indicate that tissue‐specific differences in expression of the Bz gene have been produced in alleles with mutations caused by transposable elements Ac and Ds. These mutations may affect either the amount of Bz transcription or the stability of the UFGT polypeptide. The sequence or spacing in the ‐63 region of the Bz promoter appears to be critical for maximum expression in aleurone and husk but not in pollen and pigmented seedling tissue.
Genome juggling by transposons: Tam3‐induced rearrangements in Antirrhinum majus
Authors: Martinm Cathie , Lister Clare
Published: May 2005

Transposable elements are well known for their ability to generate large‐ and small‐scale rearrangements of the sequences flanking their insertion sites. These include deletions, inversions, and duplications.

Tam3, a transposon from the Snapdragon (Antirrhinum majus), is highly active in the generation of such rearrangements. We have analysed a number of Tam3‐induced rearrangements at the nivea (niv) locus by Southern blotting, cloning, and sequence determination. The data obtained from these analyses have led to an understanding of the mechanisms by which these complex alleles were formed. We have shown that the primary rearrangements usually occur without excision of the element and therefore result from aberrant transposition attempts. Subsequent rearrangements may occur on excision of the element.

Finally, we suggest how the analysis of such rearrangements may not only provide information about Tam3 transposition but also show how transposon‐induced rearrangements may influence the structure and function of the genome as a whole.
Mu1‐Induced mutant alleles of maize exhibit background‐dependent changes in expression and RNA processing
Authors: Strommer Judith , Ortiz Daniel
Published: May 2005

We have examined effects of mutations created by transposition of the Mu1 element of maize into genes coding for Adh1 and Sh1, by means of allozyme measurements, DNA and RNA hybridization, cloning, and sequencing. From our analysis of mutant alleles we conclude that the element acts both to reduce steady‐state levels of RNA and to induce aberrant processing of primary transcripts. We also conclude that genetic background can exert considerable influence in determining the degree to which Mu affects these aspects of gene expression.
Genetic analyses of putative two‐element systems regulating somatic mutability in Mutator‐induced aleurone mutants of maize
Authors: Robertson Donald S. , Stinard Philip S.
Published: May 2005

The Mutator transposable element system (Mu) of maize has been responsible for the induction of numerous mutable aleurone mutants of maize. Unlike similar mutants induced by other transposable element systems, the mutability of Mu‐induced mutants did not seem initially to be regulated by an independent autonomous or regulator element. However, in a continuing study of two Mu‐induced a1 mutable mutants (a1‐Mum2) and a1‐Mum3, lines have been obtained that give evidence of an independently segregating regulator of somatic mutability. Data from several generations of crossing are presented indicating that intense somatic mutability in many of these stocks is under the control of an independent regulator. However, testing of other lines, which initially gave evidence of the presence of an independent regulator, were negative. Some of these latter lines could be expected to have Mutator elements that were modified (methylated) at sites recognized by certain restriction endonucleases. Modification of Mu elements, which is known to affect the expression of somatic mutability, might, at times, be responsible for producing conditions that mimic the segregation of an independent regulator. Lines with stable derivatives of the a1‐Mum2 and a1‐Mum3 can recover intense somatic mutability by crossing with germinally active Mutator stocks. Thus, active Mutator lines contain regulator elements and evidence is presented suggesting that such lines have multiple copies of these elements. Most a1‐ Mum2 and a1‐Mum3 stocks segregating for a regulator do not have germinal Mutator activity. Thus the presence of one or a few putative regulator elements does not necessarily account for the high level of germinal activity in most Mutator stocks.
Genetic and molecular characterization of a‐mrh‐Mrh, a new mutable system of Zea mays
Authors: Shepherd Nancy S. , Rhoades M. M. , Dempsey Ellen
Published: May 2005

A new allele of the maize A1 gene, a gene required for anthocyanin pigment biosynthesis, was identified in a genetic stock exhibiting a high frequency of chromosome breakage at the second microspore mitosis. This allele, a‐mrh, is unstable in both somatic and germinal tissue when an independent locus, Mrh, is present in the genome. a‐mrh was molecularly cloned, and a 246 bp DNA insertion with characteristics of a transposable element was identified within the fourth exon of the gene. Southern blot analysis of germinal derivatives of a‐mrh suggests that the DNA insert rMrh is excised from the locus when a wild‐type phenotype is restored. Genetic crosses with components of other two‐element mutable systems of maize failed to induce mutability. We therefore conclude that rMrh is a member of a new, two‐element transposon system of maize. The genetic and molecular characteristics of the elements involved are discussed with respect to stress‐activated transposition, response of an element to developmental signals, and a possible new role of plant transposons in gene evolution.
Unstable genes affecting chloroplast development in soybean
Authors: Chandlee Joel M. , Vodkin Lila O.
Published: May 2005

Y18 is a nuclear gene of soybean (Glycine max) necessary for normal chloroplast development. An unstable allele (Y18‐m) of the Y18 gene has been previously characterized genetically [Peterson and Weber: Theor Appl Genet 39:156‐162, 1969.] Plants homozygous for the unstable allele produce leaves that exhibit a variegated pattern of green and yellow leaf sectors, indicating somatic mutability events. Germinal instability is detected by the recovery of either pure breeding dominant green (rare) or pure breeding recessive yellow (frequent) plants from the mutable stock. In contrast to most unstable genes identified in other plant systems, the Y18‐m mutation is from the dominant green state to the recessive yellow state, producing a pattern of “reverse variegation.” Current work has focused on further characterization of this mutation at the whole plant level as well as at the biochemical level. These results include observations on the cell‐ and tissue‐type specificity of the mutation, stability of the recessive yellow mutation, and a biochemical analysis of mutant and normal thylakoid membranes to identify the specific polypeptides affected by the y18 mutation. Several polypeptides of the thylakoid membranes are missing, and many, including the major light harvesting complex (LHCP) polypeptides, are reduced. Messenger RNAs for LHCPII were also reduced to a greater extent than other leaf transcripts in the yellow sectors of variegated plants. A comparison of Y18‐m to other soybean mutable genes and transposable element insertions is made.
Alfalfa transposable elements and variegation
Authors: Bingham E. T. , Clement W. M.
Published: May 2005

Alfalfa with unstable anthocyanin pigmentation has been independently discovered on six occasions since 1958. Genetic studies showed that each of the six unstable stocks was due to an allele mutable at the basic anthocyanin locus C2 in alfalfa. The alleles are designated c2‐m1 through c2‐m6. Variegated phenotypes of m1, m2, and m3 are similar and express reversion from the recessive to the dominant state. This reversion produces streaks and sectors of pigment in flower petals and seeds that are otherwise white. Reversion occurs at various times in development and may result in periclinal chimeras. The c2‐m4 allele is unique in that it arose during tissue culture, whereas the other mutables were discovered in plant populations. Interestingly, m4 is very stable in planta and only rarely produces a sectored flower, but is very unstable in vitro as measured by about 23% revertant plants regenerated from tissue cultures. Most m4 reversion occurs relatively early in development and results in completely pigmented in vitro revertants, and in large sectors on in planta revertants. Alleles m5 and m6 are phenotypically and genetically similar. Their flowers are basic purple with white streaks thus representing mutation from dominant purple to recessive white. White progeny of m5 and m6 are very stable both in planta and in vitro; reversion of white to purple was never observed. Thus, the loss of function of the dominant allele results in a stable recessive or a deficiency. The absolute stability of m5 white derivatives favors the deficiency model, because transposable element mutations might show reversion. Finally, several mutations are described that reoccur in the mutable populations. It is speculated that they are recent mutations due to transposition of transposable elements.
Transcripts of individual Drosophila actin genes are differentially distributed during embryogenesis
Authors: Tobin Sara L. , Cook Patricia J. , Burn Timothy C.
Published: May 2005

The temporal and spatial patterns of accumulation of transcripts from individual actin genes during Drosophila embryogenesis have been determined by in situ hybridization. We describe the subcloning into transcription vectors of unique DNA fragments derived from the 3′ transcribed, but nontranslated region of each actin gene. These fragments then served as templates for the synthesis in vitro of single‐stranded, radioactive gene‐specific RNA probes. Probe characterization and hybridization to developmental RNA blots are presented, demonstrated the independent developmental accumulation of actin transcripts from each gene. Each gene‐specific probe has been hybridized in situ to the transcripts present in embryonic frozen sections. The results of these experiments have demonstrated that transcripts from each actin gene accumulate differentially in developing Drosophila tissues. The 5C and 42A actin genes are cytoplasmic actin genes, with transcripts distributed in all cells and tissues of the developing embryo. Therefore these genes presumably encode the cytoplasmic actins used for functions common to all cells. Transcripts from both cytoplasmic actin genes are evenly distributed in preblastoderm embryos, becoming localized to the periphery at blastoderm formation [5C: Burn et al.: Dev Biol 131:345‐355, 1989]. Later in development, levels of these cytoplasmic transcripts vary in specific tissues. While the patterns of localization of 5C actin transcripts have been published [Burn et al.: Dev Biol 131:345‐355, 1989], differential neurological localization is presented here; 42A transcripts are localized at higher concentrations in the midgut, the brain, nerve cord, and gonad. Both 87E and 57B transcripts accumulated in the developing larval body wall musculature, but at differing levels and in differing patterns. Transcripts of the 79B and the 88F actin genes were undetectable in embryos. The results of these experiments suggest dedicated contributions of individual actin genes to complex developmental processes.
Expression of NA, K‐ATpase α and β subunit genes during preimplantation development of the mouse
Authors: Watson Andrew J. , Pape Cynthia , Emanuel Janet Rettig , Levenson Robert , Kidder Gerald M.
Published: May 2005

NaK‐ATPase is a plasma membrane enzyme that plays a critical role in eutherian blastocoel formation (cavitation) by pumping Na+ into the extracellular space enclosed by the trophectoderm. Previous experiments with the mouse had shown that the α (catalytic) subunit of the enzyme becomes detectable by immunocyto‐chemistry in the late morula, just prior to the onset of cavitation. In the present study we have used cDNAs corresponding to three mRNA isoforms of the α subunit and a β subunit to determine which genes are expressed during preimplantation development and to explore the timing of their expression. Of the three α subunit cDNAs tested by Northern blot hybridization with blastocyst RNA, only α1 produced a hybridization signal, recognizing a single mRNA about 4 kb in length. This mRNA is relatively abundant in zygotes but barely detectable by the 2‐cell stage and then accumulates steadily thereafter to reach its preimplantation maximum in blastocysts. The β1 cDNA detected mRNA of about 2.6‐2.8 kb. This mRNA is present in zygotes but could not be detected in 2‐, 4‐, or 8‐ cell stages; it is present at a low level in late morulae and is abundant in blastocysts. The temporal profile of accumulation of β1 mRNA thus matches more closely than does α1 the timing of appearance of the catalytic subunit. This suggests that the β subunit may regulate production of the holoenzyme and hence the timing of cavitation.
Mutations affecting embryonic cell migrations in Caenorhabditis elegans
Authors: Manser James , Wood William B.
Published: May 2005

Four recessive mutations that affect long‐range embryonic migration of the two canal‐associated neurons (CANs) in C. elegans were isolated and characterized with the goal of identifying genes involved in control of directed cell movement. Mutant animals were identified initially by their “withered” tails, a phenotype associated with abnormal CAN migration; the mutants were then analyzed for abnormal cell migrations by Nomarski microscopy. Based on genetic complementation tests, the mutations were assigned to four different loci, two new (mig‐10 III, mig‐11 III) and two previously identified (unc‐39 V, vab‐8 V). Mutations at all four loci affect CAN migration with high to moderate penetrance (the percentage of mutant animals that exhibit the phenotype). In addition, two other bilaterally symmetric pairs of neurons (ALM and HSN), the mesoblast M, and a pair of coelomocyte mother cells are affected by one or more of the mutations, generally with lower penetrance. With the exceptions of HSN and the right coelomocyte mother cell, which occasionally migrate beyond their normal destinations, the cells affected appear to migrate either incompletely or not at all. All the migration phenotypes show incomplete penetrance and variable expressivity, although genetic tests suggest that mutations at mig‐10 and vab‐8 result in complete or nearly complete loss of gene function. The variability in mutant phenotypes allowed tests for interdependence of several of the affected migrations; all those analyzed appeared independent of one another. The possible nature of the mutant defects and possible roles of these four loci in cell migration are discussed.
Molecular analysis of a phylogenetically conserved carrot gene: Developmental and environmental regulation
Authors: Seffens William S. , Almoguera Concepción , Wilde H. Dayton , Von der Haar Raymond A. , Thomas Terry L.
Published: May 2005

Extensive studies of gene expression programs in carrot somatic embryos identified a gene, designated Dc3, that serves as a reliable molecular marker for the acquisition of embryogenic potential by carrot cells in culture. The complete sequence of a carrot genomic region, DcG3, encoding a Dc3‐like mRNA, was determined. The DcG3 transcription unit contains a single intron and encodes mRNA that is expressed at high levels in embryonic tissue but is undetectable in somatic tissue of carrot. The predicted protein sequence of DcG3 is 163 amino acids and includes two approximately 50 amino acid direct repeats which in turn include additional repetitive elements with an unusual distribution of charged amino acids. Dc3 and Dc3‐like mRNAs are encoded by a small divergent gene family. Furthermore, similarities of the Dc3 gene family with genes from other plant species that are expressed in response to environmental and developmental cues suggest a possible role in seed desiccation and possibly in more general water‐stiess responses in plants. Analysis of transgenic tobacco containing a β‐glucuronidase (GUS) reporter gene fused to a 1.7 kb 5′ upstream element of DcG3 defined a promoter/enhancer complex that confers developmentally and environmentally regulated expression of GUS activity. Thus, DcG3 is phylogenetically conserved together with the trans‐acting factors required for its regulated expression in transgenic tobacco.
Characterization and expression of two sea urchin homeobox gene sequences
Authors: Wang Gordon V. L. , Dolecki Gregory J. , Carlos Ruben , Humphreys Tom
Published: May 2005

We describe two homeobox sequences, TgHbox5 and TgHboxó, isolated from the Hawaiian sea urchin Tripneustes gratilla using a Drosophila Sex combs reduced probe. Sequence analysis shows that the encoded TgHbox5 home‐odomain shares only 30‐52% amino acid identity with homeodomains encoded by previously characterized genes, establishing that it is a divergent homeobox that is not in any known class of homeoboxes. TgHbox5 is expressed in the embryo as two major developmentally regulated transcripts. one at 5.0 kilobase (kb) appearing by blastula stage and the other at 2.7 kb appearing at pluteus stage. Multiple transcripts from TgHbox5 are present at a much lower level in adult tissues and are predominantly expressed in small and large intestines. The TgHbox6 homeobox is an Antennapedia‐class homeobox, which appears not to be expressed during embryogenesis but produces abundant 3.6 and 3.2 kb transcripts in the six adult tissues examined.
Different requirements for l(1)giant in two embryonic domains of Drosophila melanogaster
Authors: Petschek Jane P. , Mahowald Anthony P.
Published: May 2005

L(1)giant is a zygotic lethal mutation which affects the embryonic development of both the labial/thoracic segments and a subset of posterior abdominal segments. Using antibodies specific for proteins encoded by several Drosophila genes to identify the compartmental origin of the defects, we show that the requirement of giant activity is different in these two embryonic domains. Anteriorly, the posterior compartment of the labial segment is missing at the blastoderm stage. Posteriorly, cells are specifically deleted by cell death within the anterior compartments of abdominal segments 5–7 during germ band elongation. In mature embryos, posterior compartment structures of the peripheral nervous system of A5–7 are fused. In addition to a different pattern of defect in the two parts of the embryo, the kind of action appears different. Anteriorly, giant resembles a gap mutation in that a particular region is missing from the blastoderm fate map, whereas in the abdominal domain, giant affects the development of anterior compartment‐specific structures.
Cis‐acting sequences and trans‐acting factors required for constitutive expression of a microinjected HSP70 gene after the midblastula transition of Xenopus laevis embryogenesis
Authors: Ovsenek Nick , Williams Gregg T. , Morimoto Richard I. , Heikkila John J.
Published: May 2005

Microinjected human HSP70 promoter‐chloramphenicol acetyl transferase (CAT) chimeric genes are constitutively expressed immediately after the midblastula transition of Xenopus embryogenesis. Analysis of a series of 5′‐deletion mutants in the HSP70 promoter revealed that sequences within 74 bases of the transcriptional start site were sufficient for strong basal activity. We investigated the role of specific sequences in the basal promoter by injecting HSP70‐CAT vectors containing linker‐scanner mutations in the basal elements (CCAAT, purine‐rich element, GC‐element, ATF/AP1, and 1ATA). Our data reveal that deletion of any of these cis‐acting elements in the basal promoter prevents expression after the midblastula stage of development. Furthermore, we have identified specific binding activities in embryonic nuclear extracts that complex with basal promoter elements (CCAAT, ATF, and GC) of the heterologous HSP70 promoter. These trans‐acting factors are detectable in nuclear extracts of early blastula embryos, and their respective binding activity increases dramatically after the midblastula transition. The expression of the human HSP70 gene after the midblastula transition of Xenopus embryogenesis requires an array of cisacting elements, which interact with specific Xenopus transcription factors.
Developmental expression of regionally specific cell surface antigens in the Xenopus gastrula
Authors: Litvin Judith , Grant Barth , Davis Lynn , Lou King Mary
Published: May 2005

Molecular markers for specific cell lineages would be useful in studies of cellular differentiation. To isolate such markers monoclonal antibodies (MoABs) were raised against plasma membranes isolated from gastrulating Xenopus embryos. Those antibodies that recognized subsets of cells within the embryo were selected by indirect immunofluorescence. The analysis of eight such MoAbs is presented. Western blot analysis showed that all but one MoAb recognized a complex pattern of glycoconjugates associated with glycoproteins. All the antigens recognized by the MoAbs were maternal in origin and displayed similar spatial patterns of pregastrular expression. This pattern of immunoreactivity at the apical surface was inherited passively during cleavage by the resulting superficial blastomeres suggesting that ectodermal specific markers of maternal origin are pre‐localized to the cortical ooplasm in mature oocytes. We suggest that these maternal components may be specific glycosyl transferases. Three different patterns of expression were observed during gastrulation as exemplified by MoAbs 1F10C1, 3A4D1, and 6F10B6. MoAb 6F10B6 was specific for both neural and non‐neural epithelium. MoAb 3A4D1 was specific for non‐neural epidermis. MoAb 1F10C1 appeared to recognize a protein epitope on an extracellular component expressed by the superificial and involuting epithelial cells. The pattern of expression for the 1F10C1 antigen suggests that it may play a role in facilitating the movement of the involuting cells during gastrulation.
Endoreduplication of nuclear DNA in the developing maize endosperm
Authors: Kowles Richard V. , Srienc Friedrich , Phillips Ronald L.
Published: May 2005

Multiparametric flow cytometry was used to analyze the development of the endosperm in Zea mays L. during the period from 8 to 20 days after pollination (dap). Nuclear size, DNA content per nucleus, and frequencies of nuclei with varying properties were measured in preparations that included all of the endosperm nuclei of single kernels of the inbred strain Al88. Characteristics of nuclear populations from different kernels on the same ear showed minimal variation. The dynamic changes of non‐mitotic cells involved in endosperm development consisted of alternating periods of DNA replication with non‐replication. Seven rounds of DNA replication had occurred in some nuclei in the later developmental stages with the rate averaging approximately one round per 24‐hour period. Analysis of the DNA levels in the nuclei showed an exact doubling pattern indicating an endoreduplication process, that is, replication of the entire genome during each round. The loosely organized polytenization of the chromatin occurred to varying extents among the nuclei within an endosperm. A weak positive correlation existed between DNA content and size of nuclei suggesting that DNA increases and nuclear growth may not be highly coordinated in this tissue. Increased proportions of the larger nuclei occurred in the later stages of endosperm development. Considering the entire endosperm, the average DNA content per nucleus at the 15‐dap peak level was approximately 12.8 C constituting a 2.7‐fold overall increase from 8 dap.
Temporal expression of genes encoding free radical–metabolizing enzymes is associated with higher mRNA levels during in utero development in mice
Authors: El‐hage Samar , Singh Shiva M.
Published: May 2005

The interaction of reactive oxygen metabolites with DNA is well characterized and may result in mutagenesis, chromosome aberrations, and modulation of gene expression. Superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH‐Px) catalyze enzymatic reactions to remove oxidant stresses, particularly O2− and H2O2. The role of these enzymes during in utero development of the embryo and the developmental pattern of expression of the embryonic genes encoding them is not known. We examined the in utero developmental expression and activity of the three free‐radical–metabolizing enzymes in mice. We collected mouse fetuses at different stages of development and examined total RNA populations by Northern and slot blots using gene‐specific cDNA probes. In addition to quantifying the probe‐specific RNAs, activities of the three enzymes were also evaluated on the same tissue samples.

The gene‐specific RNAs and the associated enzyme activities are detectable with somite formation (day 8 postcoitus [p.c.]) in mice. The relative RNA values for each of the genes studied are higher in in utero stages as compared with the adult. The specific activities of these enzymes, on the other hand, follow a characteristic increase with development and growth. The relative RNA levels for each of the genes studied are higher during in utero growth and development than the relative enzyme activity values (between day 8 and day 18, third trimester) in the liver and carcass. This may suggest that the mRNA specific to these genes may accumulate in utero and are not translated immediately. Such accumulating transcripts are translated efficiently after birth, when these enzyme are particularly needed with the advent of aerobic respiration.
Gene interactions and epigenetic variation in transgenic plants
Authors: Matzke M. A. , Matzke A. J. M.
Published: May 2005

Unusual gene interactions were observed in several doubly transformed tobacco plants which were obtained following sequential transformation steps using two T‐DNAs encoding different selection and screening markers. The expression of T‐DNA‐I, which encoded kanamycin resistance (Kanr) and nopaline synthase (NOS), was suppressed in some, but not all, of the double transformants after the introduction of T‐DNA‐II, which encoded hygromycin resistance (Hygr) and octopine synthase (OCS). Double transformants in which T‐DNA‐I had been inactivated could produce KanrNOS+ progeny, but these were shown to lack T‐DNA‐II, thus establishing the role of this T‐DNA in the suppression of T‐DNA‐I. Reversible cytosine methylation of the promoters of T‐DNA‐I genes was shown to correlate with their activation/inactivation cycle. In this paper we pursue further the questions of the mechanism of suppression of T‐DNA‐I genes by T‐DNA‐II, and also the timing and extent of demethylation of T‐DNA‐I promoters in Kanr progeny following the loss of T‐DNA‐II. We propose that the suppression is due to the competition between homologous regions on each T‐DNA for binding to nuclear sites with fixed locations. We further suggest that incomplete demethylation patterns of T‐DNA‐I promoters in Kanr progeny reflect the existence in the shoot apex meristem of two cell populations, which have either methylated or unmethylated T‐DNA‐I promoters, respectively. Thus, Kanr progeny are epigenetic chimeras with respect to the expression of T‐DNA‐I genes.
Bacterial and firefly luciferase genes in transgenic plants: Advantages and disadvantages of a reporter gene
Authors: Koncz Csaba , Langridge William H. R. , Olsson Olof , Schell Jeff , Szalay Aladar A.
Published: May 2005

Genes encoding light‐emitting luciferase were recently isolated from luminous marine bacteria and fireflies. Expression of luciferase genes in diverse organisms is a unique way for studying gene expression by simple and sensitive measurement of light. Recent advances in application of luciferase reporter genes are reviewed and documented by examples of in vivo visualization of their expression in transgenic plants.