bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of prenatal heat stress at mid‐ and late gestation on the learning of mature guinea‐pigs
Authors: Lyle J. G. , Jonson K. M. , Edwards M. J. , Penny R. H.
Published: May 2005

Mature guinea‐pigs which had been heat stressed at different gestational ages along with their treated and untreated controls were tested on a black‐white serial discrimination task with 1 reversal. A significant difference resulted between animals stressed at 40‐44 days gestation and their treated controls, but only on perseverative errors on the reversal task. No differences existed between animals stressed at 56‐60 days gestation and their treated controls, nor between the various control groups.
Zebrafish R‐cadherin (Cdh4) controls visual system development and differentiation
Authors: Babb Sherry G. , Kotradi Shannon M. , Shah Bijal , Chiappini‐Williamson Christin , Bell Lauren N. , Schmeiser Glen , Chen Elbert , Liu Qin , Marrs James A.
Published: May 2005

In zebrafish, R‐cadherin (cadherin‐4 or Cdh4) is expressed in the retina and in retinorecipient brain regions, suggesting that Cdh4 functions during visual system development. Cdh4 function was examined during retinogenesis and retinal axon outgrowth using antisense morpholino oligonucleotides and mutant Cdh4 construct expression. In knockdowns, Cdh4 was reduced or absent, eyes were small, and retinae lacked discrete laminae. Increased cell death produced the small eye phenotype. Zn5‐, Pax6‐, and zpr‐1–positive cells were reduced or absent in knockdown retinas but, when present, were in the correct laminae. Cdh4 knockdowns had sparse or absent retinal ganglion cell axons. When present, axons projected contralaterally but lacked fine branching and failed to reach the tectum or arborize the entire tectum. Mutant Cdh4 construct expression during retinal ganglion cell differentiation reduced or ablated neurite formation. Cdh4 is necessary for neural retina survival and differentiation, and required for normal retinotectal projection formation and tectal arborization. Developmental Dynamics 233:930–945, 2005. © 2005 Wiley‐Liss, Inc.
Peptides of normal and variant cells of tobacco
Authors: Carlson Peter S.
Published: May 2005

Polypeptides solubilized from established normal and variant cell lines of Nicotiana tabacum L cv “Wisconsin 38” have been analyzed by one‐dimensional and two‐dimensional gel electrophoresis. There was little variability observed in the polypeptide profile in an established cell line; polypeptides present in different clonal lines of cells, all derived from an initial established cell culture, were very similar, if not identical. However, a large fraction of the observed polypeptides present in cytokinin‐habituated cell lines (up to 3.8% of the total polypeptides analyzed by two‐dimensional gel electrophoresis) were different from those found in the cytokinin‐requiring cells from which they were selected. The habituated nature of the selected cell lines was demonstrated to be epigenetic; tissue cultures that were reisolated from plantlets regenerated from habituated cell lines did require cytokinin. Further observations demonstrate: (1) that epigenetic events that alter a cellular phenotype change the expression of a relatively large number of polypeptides, (2) that a single epigenetic phenotype may be the result of any one of a number of possible patterns of gene expression, and (3) that epigenetic events are not random events.
Inhibition by ammonia of intracellular cAMP accumulation in dictyostelium discoideum: Its significance for the regulation of morphogenesis
Authors: Schindler J. , Sussman M.
Published: May 2005

Two compounds, ammonia (NH3) and 3′5′ cyclic AMP (cAMP) act as specific morphogens in regulating the development of Dictyostelium discoideum [1–11]. A previous study [12] demonstrated that NH3 at concentrations that affect the course of morphogenesis completely inhibits the extracellular release of cAMP by aggregation competent cells incubated in shaken suspension. The present study extends this finding in two respects:

Exposure of aggregation competent cells to NH3 (supplied as ammonium carbonate) is followed within a few minutes by the complete disappearance of intracellular cAMP. Subsequent removal of NH3 is followed by a rapid, complete restoration of the level. Neither the disappearance nor the reappearance is affected by the presence of cycloheximide, an inhibitor of protein synthesis.

In a mutant strain of D discoideum, greatly increased sensitivity to NH3 as a regulator of morphogenesis is coupled with a correspondingly increased sensitivity to NH3 as an inhibitor of cAMP accumulation.

These results are consistent with a recently proposed [13, 14] model of morphogenetic regulation that is based on the supposition that NH3, by inhibiting cAMP production, restricts cAMP accumulation to specified constrained areas within the developing multicellular aggregate and thereby dictates the course of morphogenesis and cytodifferentiation.
A genetic system for alternative stable characteristics in genomically identical homozygous clones
Authors: Sonneborn T. M. , Schneller Myrtle V.
Published: May 2005

Paramecium tetraurelia, stock d113, although completely homozygous, produces two kinds of genomically identical clones: N (nondischarge) clones incapable of trichocyst exocytosis (discharge) from intact cells in response to picric acid; and D (discharge) clones that do respond. These alternatives are irreversibly determined (at 27°C) during a determination sensitive period the first day after fertilization (autogamy, conjugation, or cytogamy): D parents are always determined to produce D progeny; N parents produce mostly N progeny if kept in exhausted medium, but mostly D progeny if kept in bacterized nutrient medium, throughout the sensitive period. If connecting bridges between mates persist long after the time for pair separation, the N member of N×D conjugant and cytogamous pairs produces D progeny even if exposed to exhausted medium throughout the sensitive period, thus indicating the presence in D mates of a D‐determining cytoplasmic factor, δ, which overrides effects of external conditions. N and D determinations are brought about on newly developing somatic nuclei (macronuclear anlagen). After macronuclear development has been completed, determination is irreversible in it and its descendant macronuclei. M (mixed) clones produce N, D, and partial D cells; within these clones, diverse subclones can be selected. Crosses of d113 (N)×standard wild stock 51 (D) yield no segregation in F2, indicating no genomic difference between d113 (N) and wild type (D), δ may be a genic product regulating its own production. This results in “cytoplasmic inheritance” of D vs N in crosses of D×N followed by exhausted medium during the sensitive period. As with the only other well‐analyzed comparable example, mating types, neither a genetic nor an epigenetic interpretation has yet been excluded for this system of developmental differentiation.
Mutations affecting the initiation of plasmodial development in Physarum polycephalum
Authors: Gorman Jessica A. , Dove William F. , Shaibe Eva
Published: May 2005

In the heterothallic myxomycete Physarum polycephalum, uninucleate amoebae normally differentiate into syncytial plasmodia following heterotypic mating. In order to study the genetic control of this developmental process, mutations affecting the amoebal‐plasmodial transition have been sought. Numerous mutants characterized by self‐fertility have been isolated. The use of alkylating mutagens increases the mutant frequency over the spontaneous level but does not alter the mutant spectrum. Three spontaneous and 14 induced mutants have been analyzed genetically. In each, the mutation appears to be linked to the mating type locus. In three randomly selected mutants, the nuclear DNA content is the same in amoebae and plasmodia, indicating that amoebal syngamy does not precede plasmodium development in these strains. These results indicate that a highly specific type of mutational event, occurring close to or within the mating type locus, can abolish the requirement for syngamy normally associated with plasmodial differentiation. These mutations help define a genomic region regulating the switch from amoebal to plasmodial growth.
Differential expression of alloantigens of the major histocompatibility complex on unfertilized and fertilized mouse eggs
Authors: Heyner Susan , Hunziker R. D.
Published: May 2005

Mouse oocytes at the dictyate and metaphase II stages as well as fertilized eggs have been studied by indirect immunofluorescence for the expression of H‐2 histocompatibility antigens on surface membranes. Serologically specific reactivity to H‐2 antibody was observed as patchy fluorescence distributed over the surface of the oocyte membrane. In contrast, one‐cell zygotes exhibited variable reactivity, and early two‐cell stages were negative. Absorption studies confirmed the serologic specificity of the reactivity on oocytes, which could be shown to be due to H‐2 antibody. The results suggest that fertilization results in altered expression of major histocompatibility complex surface antigens, and confirms earlier studies that cleavage stage mouse embryos are not reactive with H‐2 antibody.
Patterns of protein synthesis following heat shock in pupae of Drosophila melanogaster
Authors: Chomyn Anne , Moller Galina , Mitchell Herschel K.
Published: May 2005

Pupae of Drosophila melanogaster were heat‐shocked under conditions required to induce phenocopies in more than 90% of the flies that subsequently emerge. The effects of these treatments on protein synthesis in two tissues (thoracic epithelium and brain) were followed for several hours after the heat treatments. Results from pulse‐labeling and protein separations on sodium dodecylsulfate (SDS) acrylamide gels showed a virtually complete cessation of protein synthesis immediately after the shock, followed by a noncoordinate resumption of the starting pattern. Similar experiments following double heat shocks demonstrated a more rapid resumption of synthesis of heat shock proteins after two successive heat treatments than after a single one.
Maternal X chromosome expression in mouse chorionic ectoderm
Authors: Frels William I. , Rossant Janet , Chapman Verne M.
Published: May 2005

An electrophoretic variant of the X‐linked enzyme phosphoglycerate kinase (PGK‐1) has been used to study regulation of X chromosome expression in the diploid derivatives of the trophectoderm at 8–8.5 days post coitum in the mouse. These derivatives included the chorionic ectoderm and the polar trophoblast. The biochemical analysis suggests that only the maternally derived X chromosome (Xm) is expressed in the diploid trophectoderm derivatives. Cell selection and maternal tissue contamination were ruled out as possible causes of the observed Xm expression. From these and other results, we conclude that all derivatives of the trophectoderm, along with the primitive endoderm, express only Xm, whereas derivatives of the primitive ectoderm show random X chromosome expression.
Tissue microenvironment and the genetic control of hair pigment patterns in mice
Authors: Galbraith Donald B. , Wolff George L. , Brewer Nancy L.
Published: May 2005

This study was conducted to assess microenvironmental variability within integumental tissue of genetically identical mice with respect to a specific cellular response: cyclic synthesis of yellow and black pigment by hair bulb melanocytes. Crosses were performed within and between inbred strains of mice that were isogenic with the exception of a single gene substitution at the agouti locus. Agouti locus genes included the Avy, Aw, A, atd, at, ax, am, and a alleles. The pigment patterns of dorsal, flank, and ventral hairs of the first and third hair generations and of hairs growing in special integumentary areas such as the pinna, tail, and hind foot were studied. It was found that the amount of yellow pigment synthesized by hair bulb melanocytes within genetically identical mice is both agedependent and conditioned by the integumentary environment. Furthermore, the special integumentary regions produce hairs with a variety of pigment patterns in which the distribution and relative amounts of black and yellow pigments do not necessarily conform to dominance relationships expected among agouti locus alleles as judged by their effects on the pigmentation of the dorsal pelage. We conclude that within genetically uniform integumental tissues, microenvironmental differences occur and are reflected as alterations in the metabolic pattern of differentiated cells.
Genomic exclusion in Tetrahymena thermophila: A cytogenetic and cytofluorimetric study
Authors: Doerder F. P. , Shabatura S. K.
Published: May 2005

Genomic exclusion is an aberrant form of conjugation of Tetrahymena thermophila in which the genome of a defective conjugant is excluded from the genotype of the exconjugant progeny. This paper is concerned with the cytogenetic and nucleocytoplasmic events of genomic exclusion in senescent clones A*III and C*. In crosses between A*III or C* and strain B, functional, haploid gametic nuclei are formed only in the strain B cell. In some instances one of the gametic nuclei divides prior to transfer of the migratory gametic nucleus, and both products then undergo DNA synthesis. Two alternative cytogenetic pathways are followed after transfer of the migratory nucleus. In the first, the conjugants separate without further micronuclear divisions. This pathway was most common in A*III genomic exclusion. In exconjugants the former gametic nuclei undergo both DNA synthesis and (presumably) intranuclear separation of centromeres to restore micronuclear diploidy. The old macronucleus of each exconjugant is retained without autolysis. This class of exconjugant survives and contributes genes to future sexual progeny. In the second cytogenetic pathway the gametic nuclei divide and macronuclear anlagen are formed, as in normal conjugation. This pathway was more common in C* genomic exclusion. The initial DNA content of the anlagen ranges from haploid to diploid. Following two to three rounds of DNA synthesis, further macronuclear development ceases and the anlagen appear to undergo autolysis. The old macronucleus condenses and also undergoes autolysis, as in normal conjugation. Except for rare C* exconjugants, in which macronuclear development is completed, anlagen‐bearing genomic exclusion exconjugants die. Death may be caused by aneuploidy, errors in the timing or receptivity to signals for autolysis, or the inability of anlagen‐bearing exconjugants to feed. Anlagenbearing conjugants are frequently abnormal with respect to the number of anlagen and micronuclei. Most of the anomalies can be explained by postulating errors in the timing of both developmental signals and nuclear divisions. Rare conjugants in which gametic nuclei divide but do not give rise to macronuclear anlagen are also observed. In these instances, the old macronuclei condense and undergo autolysis. Destruction of the old macronucleus therefore is independent of the presence of macronuclear anlagen and requires cell pairing in order to be initiated.
Complex cis‐acting regulatory genes demonstrated in Drosophila hybrids
Authors: Dickinson W. J.
Published: May 2005

Drosophila heteroneura and D differens are closely related, interfertile species of the Hawaiian picture‐winged group. They display marked qualitative and quantitative differences in the pattern of expression of alcohol dehydrogenase (ADH) and an aldehyde oxidase (AO‐1). These presumptive regulatory differences are revealed by comparisons of the relative levels of these enzymes in various tissues in larvae and adults. In hybrids produced between parents carrying different electrophoretic alleles at the structural loci for these two enzymes, each allele is expressed according to the developmental program characteristic of the parent from which it was derived. This result indicates control of the differences in pattern of expression by one or more cis‐acting sites associated with each structural locus. The distribution of activity among all the three forms of these dimeric enzymes produced in hybrids indicates that the pattern differences reflect differential accumulation of enzyme molecules, not altered catalytic properties. As expected, the regulatory differences segregate with the electrophoretic markers in backcrosses.
Genetic determination of the developmental program for maize scutellar alcohol dehydrogenase: Involvement of a recessive, trans‐acting, temporal‐regulatory gene
Authors: Lai Yiu‐Kay , Scandalios John G.
Published: May 2005

The developmental program of alcohol dehydrogenase (ADH) activity in the scutellum of maize strain R6‐67 is different from that of W64A. The level of scutellar ADH activity in R6‐67 remains relatively high during the course of early sporophytic development as compared to the commonly observed pattern. In the typical inbred strain W64A, the activity of ADH declines substantially during that period. The variance values from the crosses between R6‐67 and W64A reveal that the trait is under genetic control. Detailed genetic analysis suggests that a single gene is responsible for the altered developmental program of ADH activity in R6‐67. This gene meets the criteria for temporal regulatory genes and is different from Adh2, the structural gene which codes the ADH‐2 isozyme. We have designated this gene as Adr1 (alcohol dehydrogenase regulator, #1). Adr1 is unlinked to Adh2. There is no de novo synthesis of ADH in the scutellum during germination, and the difference in the activity level reflects the difference in the amount of enzyme protein as demonstrated by density labeling and rocket immunoelectrophoresis. Thus, it appears that Adr1 may regulate the degradation of ADH.
Mutations specific to spore maturation in the asexual fruiting body of dicytostelium discoideum
Authors: Williams Keith L. , Welker Dennis L.
Published: May 2005

Three mutations affecting spore maturation in the asexual fruiting body of Dictyostelium discoideum are assigned to a new locus, sprJ, on linkage group IV. Strains carrying mutations at the sprJ locus do not form mature spores, yet the cell patterning (spore, stalk and disc cell ratios) is apparently normal. These mutations will be useful to delineate branch points between the cell patterning and spore maturation pathways. There are some unusual features of the sprJ‐containing mutants. In particular each of the parent strains of the three mutants has incomplete spore maturation as determined by colony‐forming ability after heat shocking at 45°C. A mutation allowing growth in the presence of benlate (600 μg/ml), benA351, is mapped to linkage group I.
Inhibition by CIPC of mitosis and development in Dictyostelium discoideum and the isolation of CIPC‐resistant mutants
Authors: White Eileen , Scandella Dorothea , Katz Eugene R.
Published: May 2005

The anti‐mitotic herbicide isopropyl N‐(3‐chlorophenyl) carbamate (CIPC) prevents the growth of amoebae of Dictyostelium discoideum without killing the cells for a period of time equivalent to one generation. During in‐hibition, amoebae accumulate in prophase and metaphase of mitosis. After removal of CIPC, they continue through mitosis and then divide.

The addition of CIPC to amoebae under starvation conditions prevents aggregation and concomitant cell elongation. The cells, however, do not lose their ability to adhere to a surface, and they remain viable. When CIPC is added to amoebae which have formed streams, it leads to the disintegration of streams into small clusters of cells and to a loss of cell elongation.

Post‐aggregation stages of development can be inhibited by CIPC at the mound, slug, or Mexican hat stages. Slugs break apart into distinct aggregates.

Mutants resistant to CIPC can be obtained easily. Among these mutants, many become temperature sensititive for growth (27°C) or development (27°C or 15.5°C). Others show various abnormalities at the normal temperature (22°C). Most mutants are cross resistant to the microtubule inhibitors nocodazole and thiabendazole, and some are also resistant to CIPC during development.
Genetic control of the developmental program of L‐glycerol‐3‐phosphate dehydrogenase isozymes in Drosophila melanogaster: Identification of a cis‐acting temporal element affecting GPDH‐3 expression
Authors: Bewley Glenn C.
Published: May 2005

The complete developmental program of glycerol‐3‐phosphate dehydrogenase in wild type Drosophila is described with respect to activity, isozyme expression, and GPDH‐specific CRM. Variants of this developmental program have been isolated from natural populations which affect the rate of accumulation of only the GPDH‐3 isozyme in both the larval and adult stages of development. This activity variation segregates as a single gene which is tightly linked to the structural element on Chromosome II, exhibits cis‐control, and is tissue specific in expression. This gene meets all the criteria for temporal regulatory genes.
The immaturity interval in Tetrahymena: Genetic and environmental sources of variation
Authors: Nyberg Dennis , Bishop Patricia
Published: May 2005

The development of sexual maturity has been studied in Tetrahymena hegewischi. Progeny lines do not typically change from immaturity to mating with all different mating types during a single test interval, but about 30% do mature abruptly. Some testers are more likely than others to participate in the earliest mating reactions of progeny lines which do not mature abruptly. Subcaryonidal vegetative pedigrees of 10 pairs from 4 crosses revealed considerable intrapair variation in the time, measured in fissions, of maturity. The average intrapair coefficient of variation was 20%. A nested ANOVA revealed significant genomic effects on the immaturity interval, but no significant cytoplasmic or caryonidal effects; 56% of the total variation was non‐genomic. Growth in different environments had highly significant effects on the immaturity interval. Subclones grown at 27°C with alternate day transfers took on the average 2 to 3 times as many fissions to mature as sister subclones grown at 27°C with daily transfers. Subclones grown at 18°C or 34°C and transferred on alternate days had intermediate maturation times. The greatest range in the immaturity interval among lines of the same genotype was from 34 to 143 fissions. The development of maturity in this species involves genetic control of timing, but the genetic differences are obscured by a large amount of intraclonal variation and sensitivity to the environment.
The developmental appearance of androgen receptor protein and androgen inducibility of the gus gene complex in mouse kidney
Authors: Paigen Kenneth , Peterson Janice
Published: May 2005

During postnatal development of mouse kidney the androgen responsiveness of epithelial cells for β‐glucuronidase induction, cellular hypertrophy, and other enzyme inductions appears coincidentally with a rise in androgen receptor protein. Initially, a low level of receptor is present but no response is seen. Beginning at about 12 days of age responsiveness begins to increase, reaches a half‐maximal level at 18–20 days, and full responsiveness by 28–30 days. The limiting factor appears to be levels of androgen receptor protein.

Our experiments shed no light on the question of why each androgen responsive cell type in the organism differentiates the capacity to induce a different array of proteins. However, they do suggest that responsiveness of the β‐glucuronidase gene does not appear until a minimum threshold level of receptor is exceeded, and that the response of the gene may not be saturated even at the highest levels of receptor reached.
Developmental controls of morphological mutants of Phaseolus vulgaris L.: Differential expression of mutant loci in plant organs
Authors: Shii C. T. , Mok M. C. , Mok David W. S.
Published: May 2005

Developmental controls of morphological mutants of Phaseolus vulgaris L. conditioned by two independent loci, DL1 and DL2, were examined through grafting experiments and hydroponic studies. Phenotypes of mutant classes were duplicated by unions of scions and stocks derived from different genotypes. Results indicate that DL1 and DL2 regulate a root and shoot factor respectively, contributing to the mutant types. The allelic dosages of DL1 in the root and DL2 in the shoot rather than the genotype of the whole plant per se determine the severity of the mutant expression. Plants heterozygous for both loci with a temperature‐sensitive expression of the mutant phenotype were used to determine physiological components involved. The primary abnormal developmental event associated with the appearance of mutant phenotypes, the restricted root growth at high temperature, could be overcome by the addition of cytokinin in hydroponic solution. These observations suggest that DL1 and DL2 may be related to the regulation of hormonal function or metabolism.
Enzyme patterns in trisomy 19 of the mouse
Authors: Fundele Reinald , Bücher Theodor , Gropp Alfred , Winking Heinz
Published: May 2005

Activity patterns of cytosolic and mitochondrial enzymes of carbohydrate and amino acid metabolism have been measured in murine trisomy 19. In spite of marked hypoplasia, no significant alterations of the patterns (per gram of organ weight) were observed, with the exception of glutamate oxaloacetate transaminase (GOT‐1), and phosphoglycerate mutase (PGAM). Clear‐cut gene dosage effects in liver, brain, heart, skeletal muscle, and erythrocytes of fetal and newborn mice, confirm the assignment of GOT‐1 to chromosome 19. Data obtained for PGAM demonstrate that one of the two different subunits leading to organ‐specific isozyme patterns of the dimer enzyme protein is coded on chromosome 19 (gene Pgam‐1). Dosage effects are fully expressed in liver, brain, and erythrocytes (AA‐type isozyme), but not in skeletal muscle (BB‐type isozyme). Dosage effects on the hybrid AA‐AB‐BB‐isozyme pattern in the course of development of the heart muscle, were demonstrated by means of quantitative activity measurement after electrophoretic separation. The comparison of enzyme patterns of eusomic and trisomic erythrocytes, produced after injection of fetal stem cells into irradiated adult carriers (transplantation chimaeras), revealed enzyme activity ratios that were similar to those produced by erythrocytes of adult euploid and trisomic mice. This is in agreement with the chromosome assignments and dosage effects mentioned above.
Endogenous formation of prostanoids and the levels of long‐chain fatty acyl CoA derivatives in suspensive and adhesive cells from in vitro embryoid bodies of teratoma OTT 6050
Authors: Ohtsu Eiji , Hong Seong Su , Matsuzawa Taiju
Published: May 2005

Attachment of the cell surface to a substratum may play a critical role in initiating some cellular developmental commitments and in sustaining differentiation of cells that have already been specialized. Embryoid bodies of teratoma OTT6050 were divided, on day 10 of initial culture, into myogenic adhesive cells which were already (at day 6) characterized by endogenous prostaglandin (PG)I2 formation and little‐specialized suspensive cells which formed only thromboxane (TX)B2 in the same culture system. Since at day 10 both cell types reached a stationary phase in which the nature of each cell was mature enough for the analyses with mass fragmentographic technique and gas chromatography‐ mass spectrometry (GCMS), the total levels of predominant long‐chain fatty acyl CoA (acyl CoA) derivatives could be measured comparatively as methyl esters after methanolysis. It was found as a result of major differentiation that adhesive cells had a rather low ratio of arachidonyl CoA to stearyl CoA, although adhesive cells accumulated a larger total amount of acyl CoA derivatives than that accumulated in suspensive cells.
The analysis of mammalian development using allelic isozyme variants
Authors: Kidder Gerald M.
Published: May 2005

The past decade has seen an explosion of interest in mammalian embryos. Techniques of molecular and genetic analysis coupled with advances in in vitro culture and experimental manipulation of mammalian embryos have provided important insights into mechanisms of embryogenesis. Many of these recent advances have been facilitated by the use of allelic isozyme variants as autonomous cell markers or representative gene products. Investigations aimed at exploring cell lineages and cell commitment, the timing and regulation of gene expression, X chromosome inactivation, and cell interactions have depended on the availability of appropriate isozyme variants. Results from such experiments are summarized here in order to demonstrate the usefulness of this approach and to stimulate its wider application in developmental biology.
DNA heterogeneity and genetic control of tumorigenesis in nicotiana tumorous and nontumorous genotypes
Authors: Durante Mauro , Geri Chiara , Buiatti Marcello , Baroncelli Sergio , Parenti Roberto , Ronchi Vittoria Nuti , Martini Guido , Grenci Fulvio Collina , Grisvard Janine , Guillé Etienne
Published: May 2005

The possible relevance of changes in amounts of highly repetitive DNA sequences for plant differentiation and dedifferentiation processes has been suggested in several cases. Data are lacking however on (1) the genetic control of these phenomena and (2) cause‐effect relationships between DNA amplification and specific ontogenetic patterns.

The present study was carried out on a Nicotiana genetic system consisting of the tumorous amphidiploid N glauca X N langsdorffii, a nontumorous mutant of it, their F1, and a backcross to the tumorous parent. Backcross segregation ratios were shown to be compatible with a “single gene” hypothesis, the F1 plant being nontumorous but showing a low percentage of tumors induced by wounds, 6‐azauracil or X‐rays.

In vitro studies of excised pith tissue grown on Linsmaier and Skoog medium for different periods of time showed the presence, confirmed by cytological analyses, of amplification of highly repetitive sequences only in the nontumorous stock, as judged by reassociation experiments in the first 24–96 hours of culture. CsCl analytical ultracentrifugation of those sequences showed the appearance in the same stock of a heavy DNA satellite (density = 1.721 gm/ml), whose presence was also confirmed by derivative melting curves.

Amplification seemed to be essential for the initiation of cell division, which was completely inhibited in the nontumorous genotype and partially influenced in the F1 by incorporation during the critical period (24–96 hours of the primary explant) of 5‐bromo‐2′‐deoxy‐uridine.

The results are discussed in terms of an hypothesis of an integrated gene‐controlled, hormone‐mediated regulatory system of cell proliferation involving changes in target repetitive DNA sequences.
Developmentally regulated gene expression in Artemia: Histone gene expression in newly hatched larvae
Authors: Bagshaw Joseph C.
Published: May 2005

The synthesis of histones and presence of histone mRNA sequences in embryos and larvae of the brine shrimp, Artemia, were investigated. Radiolabeling of proteins synthesized in vivo followed by electrophoretic and fluorographic analysis confirmed the prediction that histone synthesis is coordinated with the wave of DNA replication in newly hatched larvae. No histone synthesis occurs during development of encysted embryos. Hybridization of cloned Artemia histone gene DNA to total cell RNA indicated that dormant encysted embryos do not contain “masked” messenger RNA.
The intracellular ratio of the membrane to the secreted form of immunoglobulin M heavy chain is a measure of the developmental stage of B cell lymphomas
Authors: Sibley Carol H. , Mar Holly A. , Mains Paul E.
Published: May 2005

Tumors of B lymphocyte origin have been used as models for normal B cells “frozen” at particular stages of their development. Surface properties, amount, and intracellular location of immunoglobulin and the synthesis of J chain have all been used as indicators of developmental stages. Each requires special techniques or yields data that are difficult to compare from one experiment to the next. For these reasons, we have developed a metric for B cell development that is simple to perform and allows quick quantitative comparisons of cell lines.

It has recently been established that the membrane (μm) and secreted (μs) forms of the IgM heavy chain differ at their extreme carboxy termini. The two proteins differ slightly in size and are easily distinguished when they are compared without their carbohydrate on sodium dodecyl sulfate (SDS) polyacrylamide gels. We have examined four mouse tumors derived from the B lymphocyte lineage whose phenotypes resemble late pre‐B cells (internal μ only; uninduced 70Z/3), small B lymphocytes (high levels of surface IgM; LPS‐induced 70Z/3, WEHI 231), lymphoblasts (both membrane and secreted IgM; WEHI 279.1), and plasma cells (copious IgM secretion; MOPC 104E). Despite the fact the 70Z/3 and WEHI 231 secrete no detectable IgM, all of the tumors synthesize at least intracellular forms of both μm and μs. The proportion of μm is stable and is characteristic of each tumor. The 70Z/3 cells and WEHI 231 cells synthesize about 75% of their total μ as μm; WEHI 279.1 cells synthesize about 30% and MOPC 104E cells about 5% of their total μ as μm. The population of LPS‐stimulated B lymphocytes shows a similar progression during its differentiation. The proportion of μm correlates with other developmentally regulated parameters (Fc receptor, Ia and plasma cell antigen levels, and J chain) and can be used as a simple metric for comparison with developing B lymphocytes and determination of the developmental stage of a B cell tumor.
Ovarian pathologies generated by various alleles of the otu locus in Drosophila melanogaster
Authors: King Robert C. , Riley Shawn F.
Published: May 2005

A comparative cytological study was made of oogenesis in flies carrying various mutant alleles of the female sterile gene otu. It resides at 22.7 on the genetic map and within subdivision 7F of the cytological map of the X‐chromosome. Each of the five ethyl methane sulfonate‐induced mutations observed falls into one of three classes. In class 1, most mutant ovarioles lack germ cells; in class 2, most mutant ovarioles contain tumorous chambers; and in class 3 mutants, chambers occur that possess defective oocytes. The otu2 allele belongs to class 1; otu1 to class 2; and otu3, otu4, and otu5 to class 3. The mutations have no effects upon female viability or upon the viability and fertility of hemizygous males. Heterozygous females are fertile and have cytologically normal ovaries. In otu5 homozygotes, all ovarioles contain egg chambers, but oogenesis is prematurely terminated to produce a pseudo‐stage 12 oocyte. Ovarioles from otu3 and from otu4 homozygotes contain both ovarian tumors and oocytes. Pseudonurse cells (PNC), which are cystocytes that have stopped dividing and have entered the nurse cell mode of development, are also abundant. PNCs contain polytene chromosomes. Since the homologs are paired, each nucleus has the haploid number of chromosomes. In chambers lacking an oocyte, the number of PNCs is less than the normal number of nurse cells. In chambers containing an oocyte, the number of accompanying nurse cells may be 15, or above or below normal. In vitellogenic chambers, the chromosomes in the nurse cells connected directly to the oocyte are more expanded than those in more distant nurse cells. The KA14 deficiency lacks the plus allele of otu. KA14 heterozygotes are fertile and have cytologically normal ovaries. When females carry KA14 and otu1, otu3, otu4, or otu5, 80% of their ovarioles are agametic. When females carry otu2 and one of the other mutant alleles, the ovarioles proceed further in development. So otu2 produces a product that has a beneficial effect on the test allele. When two different otu alleles are combined in a single fly, the phenotype of the hybrid ovary usually most resembles that of the ovary homozygous for the “stronger” allele (the otu mutant that allows oogenesis to proceed farthest). The results indicate that the product of the otu+ locus functions at least three different times during oogenesis; first to permit oogonia to proliferate, second to control the division and differentiation of germarial cystocytes, and third to facilitate the normal growth of the ooplasm. The gene product appears to be required in higher concentrations at each developmental period. The lesions produced by the mutations are thought to interfere with the stability or functioning of the gene product, and the ovarian phenotype produced by a given genotype depends upon the concentration of functional gene product available to the germ cells.
Homoeosis in Drosophila: Evidence for a maternal effect of the polycomb locus
Authors: Denell R. E.
Published: May 2005

When heterozygous, dominant mutant alleles of the Polycomb locus are associated with a variety of adult homoeotic effects. Zygotes homozygous for these alleles die as late embryos showing homoeotic transformation of head, thoracic, and abdominal segments. This study shows that embryos homozygous forPc3are more extreme than those homozygous forPc1orPc2. Moreover,Pc1/Pc3heterozygotes are more extensively transformed if their mothers werePc3/ + than if they werePc1/ +; this effect does not depend on zygotic genetic background and must be maternal in nature. Embryos homozygous forPc3are less extreme if they arise fromPc3/ + / + than fromPc3/ + mothers. These results strongly suggest that the Polycomb locus acts maternally as well as zygotically to affect early determinative decisions.
In vivo radiolabeling and turnover of sn‐glycerol‐3‐phosphate dehydrogenase in Drosophila melanogaster: Gene dosage effects
Authors: Wilkins Joseph R. , Shaffer Jacquelin B. , Bewley Glenn C.
Published: May 2005

In vivo radiolabeling of Drosophila melanogaster sn‐glycerol‐3‐phosphate dehydrogenase (E.C. 1.1.1.8; GPDH) has been accomplished by microinjection of 3H‐leucine into anesthetized flies. Comigration of immunoprecipitated radiolabeled GPDH with purified 14C‐labeled GPDH‐1 in SDS polyacrylamide disc gels has established the monospecificity of our immunoprecipitation technique. Short‐term uptake experiments have demonstrated that maximum radiolabel incorporation of total TCA precipitable protein and immunoprecipitable GPDH‐1 occurs within 4 hours postinjection, with GPDH‐1 accounting for approximately 1% of the total radiolabeled TCA precipitable protein. In order to develop the parameters for turnover studies of GPDH in Drosophila, a comparative analysis of the rates of synthesis and degradation of GPDH‐1 in flies bearing two and three doses of the structural gene have been conducted by the construction of adult flies aneuploid and euploid for the cytogenetic region 25F‐26B on the left arm of chromosome II. Short‐term uptake studies have demonstrated that the rate of GPDH‐1 synthesis in the three‐dose flies is approximately 1.58 times that found in the two‐dose euploid flies. This value is in close agreement with data obtained for steady‐state levels of CRM by rocket immunoelectrophoresis. In contrast, longterm pulse‐chase experiments have revealed that rates of GPDH‐1 degradation in these aneumploid and euploid flies appear to be identical. These data suggest that the rate of GPDH‐1 synthesis in Drosophila is primarily regulated by a tightly linked cis‐acting element which appears to act autonomously with respect to gene copy number as well as steady‐state GPDH protein levels.
Lethal bithorax complex mutations of Drosophila melanogaster show no germ line maternal effects
Authors: Kerridge Stephen , Dura Jean‐Maurice
Published: May 2005

Three Ultrabithorax (Ubx) alleles and three different deficiencies of the bithorax complex (BX‐C) of Drosophila melanogaster have been tested for maternal effects in the germ line. The dominant female sterile technique was used. The Ubx alleles and a deletion of the abdominal region of the BX‐C are homozygous viable in germ line clones and show no maternal effects. Two deletions which lack the proximal portion of the BX‐C are lethal in the female germ line indicating either that these deficiencies lack genes apart from the BX‐C that are necessary for fertility or that there are BX‐C genes that are essential for normal maternal germ line function. The significance of the bias in the isolation of only zygotic mutations at the BX‐C are discussed with respect to these results.
Chitin biosynthesis during pupal development of Drosophila melanogaster and the effect of the lethalcryptocephal mutation
Authors: Sparrow John C. , Chadfield Colin G.
Published: May 2005

Estimation of chitin deposition in the pupal and adult cuticles of adult Drosophila melanogaster during the pupal period is described. The timing of the periods of chitin deposition is compared with that deduced by previous workers using electron microscopy. The hypothesis that lethalcryptocephal mutant homozygotes are unable to evert their cephalic complexes at pupation because of excess chitin deposition is examined. The data obtained show no evidence that the mutation has any effect on chitin deposition.
Isolation and characterization of cAMP unresponsive (frigid) aggregation‐deficient mutants of Dictyostelium discoideum
Authors: Coukell M. Barrie , Lappano Sergio , Cameron Anne M.
Published: May 2005

To find mutants of Dictyostelium discoideum that are unable to respond to exogenous cAMP signals (frigid mutants), amoebae of 218 independent aggregation‐deficient mutants were treated in suspension with artificial pulses of cAMP and screened for the capacity to form EDTA‐resistant cohesion sites. Eleven frigid mutants were identified and further characterized. Using parasexual genetic techniques, these strains were assigned to five complementation groups (fgdA‐E) and the fgd loci were mapped in three linkage groups: fgdA and D in group II, fgdC in group III, and fgdB and E in group VII. Biochemical and physiological experiments with these strains indicated that fgd mutants are of two general types. When starved, strains in groups fgdB, D, and E failed to produce detectable levels of membrane‐associated cAMP phosphodiesterase, surface cAMP receptors, or extracellular phosphodiesterase inhibitor, and the cells continued to respond chemotactically to folate. Thus, these strains are probably arrested in the vegetative phase or very early in development. In contrast, strains in groups fgdA and C produced low levels of cAMP receptors and secreted phosphodiesterase inhibitor. Moreover, after starvation, some of these mutants elicited a weak chemotactic response to cAMP. Therefore, unlike the former group of mutants, these strains appear to initiate development when starved, but the process is blocked at an early stage.
DNA polymerase activity in developmental stages of Drosophila melanogaster
Authors: Dusenbery Ruth L. , Smith P. Dennis
Published: May 2005

An assay procedure was developed that allowed the first reproducible measurement of DNA polymerase activity in all developmental stages of Drosophila melanogaster. Evidence is presented that the same enzymatic species is present in extracts of embryos, pupae, and adults of both sexes and that this activity has many properties similar to vertebrate α‐polymerases. Polymerase activity per individual is low in embryos and rises steadily through larval instars, reaches a peak in early pupae, declines through the late pupal period, and remains low in newly eclosed adults of both sexes. A dramatic increase is observed in adult females as mature oocytes are formed. This pattern of enzyme activity is completely coincident with changes in DNA levels during development, and suggests that the Drosophila enzyme, like vertebrate α‐polymerases, functions in cellular DNA replication. Two mutagen‐sensitive mutants, deficient in both replication on undamaged templates and postreplication repair, were found to have normal levels of this α‐polymerase activity. Our results suggest that a single enzymatic species of α‐polymerase holoenzyme exists in Drosophila and is common to all developmental stages of this organism.
Lethal(1)fibrillardysgenesis (I(1)fdg), a mutation affecting muscle development in the embryo of Drosophila melanogaster
Authors: Newman Samuel M. , Wright Theodore R. F.
Published: May 2005

The I(1)fdg mutation demonstrates two separate phases of lethality, depending on developmental conditions. At 32–33°C, an embryonic lethality is expressed whereas at lower temperatures a larval‐pupal lethality is observed. This larval‐pupal lethality characteristically produces noncondensed, curved puparia, and since the contraction of the pupa depends on strong muscular contraction, this phase of lethality implicates some involvement of abnormal musculature. The embryonic expression of I(1)fdg at 32–33°C is the subject of this study. In these embryos, which are alive but immobile (incapable of hatching), the fibrillar organization and fiber morphology of the somatic musculature varies from being apparently normal to being grossly abnormal. While the abnormalities appear as unusual distributions of fiber organelles, abnormal convolutions of the muscle fibers, and disorganizations of fibrillar components, it seems most probable that the underlying defect ultimately responsible resides in some system essential for Z body alignment and sarcomere formation. Accompanying the embryonic lethality, certain abnormalities in midgut development are observed which at present do not appear to be related to the defects observed in the somatic muscle.
Developmental and tissue‐specific control of catalase expression in Drosophila melanogaster: Correlations with rates of enzyme synthesis and degradation
Authors: Bewley Glenn C. , Nahmias Joseph A. , Cook Julia L.
Published: May 2005

The ontogenetic and tissue‐specific expression of catalase (E.C. 1.11.1.6) has been determined in a wild type strain of Drosophila melanogaster derived from a natural population. Two distinct peaks of activity are observed during development with the first peak occurring in late third instar larvae just prior to puparium formation, and the second and larger of the two peaks occurring during metamorphosis. These peaks of catalase activity are coincident with the two major peaks of ecdysone titer. Of the tissues assayed, larval malpighian tubules, gut, and fat body demonstrated the highest specific activities. Adult abdomen exhibited a two‐ to three‐fold higher specific activity than either head or thorax. Of the abdominal tissues assayed, malpighian tubules and abdominal wall had the highest specific activities. Malpighian tubules were the only sexually dimorphic tissue with respect to catalase activity and are apparently largely responsible for an overall increase observed in female abdominal activity. Catalase‐specific CRM levels parallel the enzyme activity levels indicating that these tissue‐specific activity differences reflect differences in the rate of accumulation of catalase molecules.

Turnover studies employing the catalase inhibitor 3‐amino‐1,2,4‐triazole were conducted on head, thorax, and abdomen of male adult flies. Rates of catalase degradation were similar in the three body segments with a slightly higher rate in abdominal tissue. Therefore the different steady state levels observed largely reflect different rates of catalase synthesis.