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  • Inorganic Chemistry  (567)
  • Animals  (521)
  • Genetics  (312)
  • 1995-1999  (1,400)
  • 1950-1954
  • 1995  (1,400)
Collection
Keywords
Publisher
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  • 1995-1999  (1,400)
  • 1950-1954
Year
  • 1
    Electronic Resource
    Electronic Resource
    Segmentation and tracking of piglets in images (1995)
    Springer
    Machine vision and applications 8 (1995), S. 187-193 
    Details
    ISSN: 1432-1769
    Keywords: Tracking ; Segmentation ; Pigs ; Animals ; Computer vision
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract An algorithm was developed for the segmentation and tracking of piglets and tested on a 200-image sequence of 10 piglets moving on a straw background. The image-capture rate was 1 image/140 ms. The segmentation method was a combination of image differencing with respect to a median background and a Laplacian operator. The features tracked were blob edges in the segmented image. During tracking, the piglets were modelled as ellipses initialised on the blobs. Each piglet was tracked by searching for blob edges in an elliptical window about the piglet's position, which was predicted from its previous two positions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01215814
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  • 2
    Electronic Resource
    Electronic Resource
    Phylogenetic position of Dictyostelium inferred from multiple protein data sets (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 238-246 
    Details
    ISSN: 1432-1432
    Keywords: Cellular slime molds ; Animals ; Fungi ; Plantae ; Maximum-likelihood method ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The phylogenetic position of Dictyostelium inferred from 18S rRNA data contradicts that from protein data. Protein trees always show the close affinity of Dictyostelium with animals, fungi, and plants, whereas in 18S rRNA trees the branching of Dictyostelium is placed at a position before the massive radiation of protist groups including the divergence of the three kingdoms. To settle this controversial issue and to determine the correct position of Dictyostelium, we inferred the phylogenetic relationship among Dictyostelium and the three kingdoms Animalia, Fungi, and Plantae by a maximum-likelihood method using 19 different protein data sets. It was shown at the significance level of 1 SE that the branching of Dictyostelium antedates the divergence of Animalia and Fungi, and Plantae is an outgroup of the Animalia-Fungi-Dictyostelium clade.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00170678
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  • 3
    Electronic Resource
    Electronic Resource
    Identification of genomic regions affecting plant height in sorghum and maize (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 380-388 
    Details
    ISSN: 1432-2242
    Keywords: Genetics ; Breeding ; Sorghum bicolor Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The objective of this study was to use restriction fragment length polymorphisms (RFLPs) to determine the genetic location and effects of genomic regions controlling plant height in sorghum. F2 plants (152) from the cross CK60 x PI229828 were used. Genomic and cDNA clones (106) identified 111 loci distributed among ten linkage groups covering 1299 cM. Interval mapping identified four regions, each in a separate linkage group. These regions may correspond to loci (dw) previously identified by alleles with qualitative effects. Also, these regions identified in sorghum may be orthologous to those previously reported for plant height in maize. Gene effects and gene action varied among genomic regions. In each region, PI229828 alleles resulted in increased plant height. Each region accounted for 9.2–28.7% of the phenotypic variation. Positive, additive effects ranged from 15 to 32cm. Tallness was dominant or overdominant and conferred by alleles from PI229828 for three quantitative trait loci (QTL). At the fourth QTL, PI229828 contributed to increased plant height, but short stature was partially dominant. One digenic interaction was significant. The presence of a PI229828 allele at one region diminished the effects of the other region. A multiple model indicated that these four regions collectively accounted for 63.4% of the total phenotypic variation. The utility of this information for germplasm conversion through backcross breeding is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221980
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  • 4
    Electronic Resource
    Electronic Resource
    Diallel analysis for mineral element absorption in tropical adapted soybeans [Glycine max (L.) Merrill] (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 707-713 
    Details
    ISSN: 1432-2242
    Keywords: Mineral stress ; Nutrient efficiency ; Aluminium tolerance ; Inheritance ; Genetics ; Breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Brazilian tropical adapted soybeans contains, in addition to superior morphological characters, genetic factors for tolerance to cultivation in acidic, mineral-stressed soils. However, the selection process for these hindrances has been empirical, and information on the genetics of mineral element uptake by the plant is necessary. The objective of this investigation was to identify the mode of inheritance for the absorption of phosphorus, potassium, calcium, magnesium, iron, aluminium, manganese, zinc and copper in a 9 × 9 diallel cross. General combining ability (GCA) was higher than specific combining ability (SCA), with the exception of copper, manganese and zinc, indicating predominantly additive effects. The ratios of GCA/SCA varied between 3.4 (calcium) and 8.5 (magnesium). The regression of covariance (Wr) on variance (Vr) showed that the additive-dominance model explained the genetic differences in this germ plasm. However, the detection of overdominance could be related to possible heterozygosity in the parental varieties for mineral absorption. Broad-sense heritability values were higher than narrow sense heritability values for aluminium, iron, potassium, calcium and magnesium, being in the range of 67.9–86.9% and 42.0–56.6%, respectively. This is an indication that soybeans can be further improved to efficient utilisation of nutrients and to tolerate toxic factors in the soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222137
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  • 5
    Electronic Resource
    Electronic Resource
    Allelic relationships between genes for resistance to tomato spotted wilt tospovirus in Capsicum chinense (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 146-149 
    Details
    ISSN: 1432-2242
    Keywords: Capsicum chinense ; Resistance gene ; Genetics ; Pepper ; Tomato spotted wilt virus ; Tospoviruses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pepper (Capsicum chinense Jacq.) has been reported to be an important reservoir of resistance genes to tomato spotted wilt virus (TSWV). The genes for TSWV resistance present in three C. chinense lines (‘PI 152225’, ‘PI 159236’ and ‘Panca’) were investigated for allelism. All resistant lines were crossed with each other. Parents, F1, backcrosses and F2 populations (including reciprocals) developed from those crosses were mechanically inoculated with a highly virulent TSWV isolate. Susceptible C. annuum cv ‘Magda’ was used to check inoculum virulence. Fifty plants of the F1 hybrids; ‘Magda’ x ‘PI 152225’, ‘Magda’ x ‘PI 159236’, and ‘Magda’ x 'Panca, were also inoculated with the TSWV isolate. The resistance response in all C. chinense sources was associated with a localized, hypersensitive-like reaction that was phenotypically expressed as a prompt formation of large local lesions accompanied by premature leaf abscission. All F1 generations presented a final score of resistant; indicating that the expression of resistance to TSWV is conditioned by a dominant gene regardless of the source. The absence of segregation for resistance to TSWV that was observed in all generations of the crosses between C. chinense lines indicated that either a tightly linked group of genes exists or that the resistance is governed by the same single major gene (probably the already described Tsw gene). Previous reports have indicated that the Tsw gene is not effective against tospovirus members of serogroup II, i.e. tomato chlorotic spot virus (TCSV) and groundnut ring spot virus (GRSV). In the assay described here, all of the C. chinense lines showed, after mechanical inoculation, an identical susceptibility response to the TCSV and GRSV isolates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221009
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  • 6
    Electronic Resource
    Electronic Resource
    Domestication via hybridization of the wild tetraploid oats Avena magna and A. murphyi (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 639-646 
    Details
    ISSN: 1432-2242
    Keywords: Gene introgression ; Genetics ; Linkage ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The wild tetraploid (2n=28) oat species Avena magna and A. murphyi have been domesticated by having been transferred from the common oat, A sativa (2n=42), the characteristics of non-shedding spikelets glabrous and yellow lemma, and reduced awn formation. Domestication has been achieved by crossing the common oat with either of the tetraploid species and then backcrossing the pentaploid hybrids with pollen of the tetraploid wild parent. Among the BC plants obtained only a few produced some seeds. Fertile tetraploids exhibiting the domesticated syndrome have been selected for in the F2 generation. Although morphologically they were almost indistinguishable from the common oat, they were tetraploids. Wild x domesticated A. magna hybrids were vigorous and fertile. They retained their spikelets at maturity, lemma color and pubescence were intermediate between the parental lines, and awns were formed only on the lower floret of the spikelet. Each of these characteristics segregated in a 3∶1 fashion, indicating single gene control, as in the common oat. These four characteristics formed a linkage group in one F2 family and two linkage groups in the other two families. The usefulness of the domesticated tetraploids for oat research and production has been discussed. Taxonomically, the domesticated tetraploids were ranked as subspecies: A. magna ssp. domestica, and A. murphyi ssp. rigida.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223291
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  • 7
    Electronic Resource
    Electronic Resource
    Sex segregation ratio and gender expression in the genus Actinidia (1995)
    Springer
    Sexual plant reproduction 8 (1995), S. 129-132 
    Details
    ISSN: 1432-2145
    Keywords: Sex control ; Disomic segregation ; Dioecy Kiwifruit ; Genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sex segregation ratio was checked in bi-parental families of Actinidia deliciosa (2n=6x=174) obtained by crossing four females (A12, Mo3, Br4, Hw1) with two males (T2, M1) and one fruiting male (M3h, subandroecious) according to a factorial mating design. The M3h fruiting male was also selfed. The sex ratio was checked in maternal families of A. kolomikta (2n=2x) and A. chinensis (2n=2x) as well as in A. deliciosa. Seedlings of both diploid species took 3–4 years to progress beyond juvenility, whereas a noticeable number of seedlings from biparental crosses of A. deliciosa involving A12 and Hw1 as seed parents were still non-flowering after seven growing seasons. Open-pollinated families of both diploid and hexaploid species as well as most families from biparental crosses showed a sex segregation ratio approaching 1∶1. Subandroecious lines with different degrees of ovary and pistil development appeared in proportions of 0–4.2%, depending on the cross, but only 6 of the 2567 male vines checked were capable of setting fruit. No case of self-fertility or apomixis was detected among 1866 bagged female vines. Selfed M3h progenies gave only female and male phenotypes in a ratio of 1 female to 3 males. No off-type vines were found among these progenies. The same disomic sex segregation ratio seems to be operating at different ploidy levels in the genus Actinidia. Since selfed fruiting males produced both female and male individuals, the male sex appears to be the heterogametic one. Such evidence indicates that a monofactorial system based on one or more linked genes or on an X/Y chromosome set must be controlling sex expression. How a monofactorial sex-determining mechanism could operate in polyploids to give a 1∶1 female: male ratio is discussed. Minor modifying gene(s) seem to be responsible for the feminization of males, and their expression appears enhanced by environmental conditions. Masculinizing gene(s) seem to be lacking in female genotypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00242255
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  • 8
    Electronic Resource
    Electronic Resource
    Have fishes had their chips? The dilemma of threatened fishes (1995)
    Springer
    Environmental biology of fishes 43 (1995), S. 1-27 
    Details
    ISSN: 1573-5133
    Keywords: Conservation ; Extinction ; Rarity ; Biodiversity ; Breeding guilds ; Endemism ; Speciation ; Habitat degradation ; Environmental management ; Invasive fishes ; Genetics ; Ecology ; Stenotopy ; Captive propagation ; Legislation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The conservation status and factors threatening fishes worldwide are reviewed in order to introduce a series of one-page articles on ‘Threatened fishes of the world’, and to encourage the incorporation of information on threatened fishes into international conservation programmes. Information on fish extinction and threat rates are compared with those of other animal groups, and the unique characteristics of fish conservation problems are highlighted. At present 979 species of fishes are listed as threatened in the IUCN Red List and at least 36 species and three subspecies are listed as recently extinct. It is argued that these figures are probably gross underestimates and that they may mislead conservation authorities and resource users about the seriousness of the situation. Freshwater fishes may be the most threatened group of vertebrates after the Amphibia. Urgent action is required to save many narrowly endemic, stenotopic species from extinction, especially in Africa, Asia and South America. The conservation of common species that drive essential ecological processes is also important. Anthropogenic pressures, especially habitat degradation, the introduction of invasive species and pollution, on inland and coastal waters are particularly severe and many major fish communities are threatened with elimination throughout the world. The conservation of marine fishes is complicated by the fact that it is difficult to ascertain their rarity. The importance of the retention of genetic variation is highlighted, and both orthodox and innovative conservation measures are encouraged. Further research on minimum viable populations, genetics, and the factors that cause fishes to become vulnerable to extinction, is urgently required.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00001812
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  • 9
    Electronic Resource
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    Industrial mycology and the new genetics (1995)
    Springer
    Journal of industrial microbiology and biotechnology 14 (1995), S. 355-364 
    Details
    ISSN: 1476-5535
    Keywords: Transformation ; Fungi ; Yeast ; Genetics ; Biotechnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The genetic investigation of fungi has been extended substantially by DNA-mediated transformation, providing a supplement to more conventional genetic approaches based upon sexual and parasexual processes. Initial transformation studies with the yeastSaccharomyces cerevisiae provided the model for transformation systems in other fungi with regard to methodology, vector construction and selection strategies. There are, however, certain differences betweenS. cerevisiae and filamentous fungi with regard to type of genomic insertion and the availability of shuttle vectors. Single-site linked insertions are common in yeast due to the high level of homology required for recombination between vectored and genomic sequences, whereas mycelial fungi often show a high frequency of heterologous and unlinked insertions, often in the form of random and multiple-site integrations. While extrachromosomally-maintained or replicative vectors are readily available for use with yeasts, such vectors have been difficult to construct for use with filamentous fungi. The development of vectors for replicative transformation with these fungi awaits further study. It is proposed that replicative vectors may be inherently less efficient for use with mycelial fungi relative to yeasts, since the mycelium, as an extended and semicontinuous network of cells, may delimit an adequate diffusion of the vector carrying the selectable gene, thus leading to a high frequency of abortive or unstable transformants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01569951
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  • 10
    Electronic Resource
    Electronic Resource
    Identification of two positive transcriptional elements within the 91-base pair promoter for mouse testis angiotensin converting enzyme (testis ACE) (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 201-209 
    Details
    ISSN: 0192-253X
    Keywords: Testis ACE ; positive promoter element ; in vitro transcription ; tissue-specificity ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Testis angiotensin-converting enzyme (testis ACE) is an isozyme of ACE only expressed by male germ cells during spermiogenesis. It is the result of a strong sperm-specific promoter found within the 12th intron of the somatic ACE gene. Previous studies have localized the boundaries of the mouse testis ACE promoter as being from -91 to -9, relative to the transcriptional start site, and have suggested two important DMA regulatory elements starting at positions -55 and -32. DNA constructs were made in which these motifs were either eliminated or substituted. Each construct was tested for its ability to promote transcription in vitro, using a rat testis nuclear extract. Disruption of either motif reduced in vitro transcription to about 30% of control levels, while mutations of both elements abolished transcription. Two sites were selected inside each motif and altered by point mutation. Each of four constructs, containing a mutation at -51, -48, -30, or -28, transcribed at 29% or less the efficiency of the parent construct. The DNA element at -55, TGAGGTCA, is homologous to a consensus cyclic AMP response element. The motif at -32, TCTTAT, is located at a position analogous to a TATA box. Substitution of the -32 motif with a consensus TATA box sequence, TATAAA, stimulated transcriptional activity about 3-fold. As measured by gel mobility shift, oligonucleotides encompassing the -32 motif and the consensus TATA box formed different DNA-protein complexes. However, the -32 motif oligonucleotide was recognized by nuclear proteins prepared from either liver or testis nuclei. In this example of a tissue-specific promoter that functions only during spermatogenesis, at least two DNA elements act synergistically during in vitro transcription. © 1995 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020160212
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  • 11
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    Developmental regulation of the ovine β-lactoglobulin/human serum albumin transgene is distinct from that of the β-lactoglobulin and the endogenous β-casein genes in the mammary gland of transgenic mice (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 241-252 
    Details
    ISSN: 0192-253X
    Keywords: Human serum albumin ; β-lactoglobulin ; casein ; mammary gland ; transgenic mice ; developmental regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We compared the developmental pattern of expression of the sheep β-lactoglobulin (BLG), the chimeric BLG/human serum albumin (HSA), and the endogenous murine β-casein genes in the mammary gland of virgin, pregnant and lactating transgenic mice, both at the RNA (expression) and protein (synthesis and secretion) levels. The BLG and casein genes were expressed at very low levels in virgin animals and during early stages of pregnancy. The increase in the expression of these genes started at the second half of pregnancy and reached a peak between the end of pregnancy and day 10 of lactation. The accumulation of their RNA coincided with that of the corresponding proteins, indicating a transcriptional control of expression of these genes. The expression and secretion patterns of the endogenous casein gene in transgenic and nontransgenic mice were indistinguishable. The hybrid BLG/HSA gene constructs displayed distinct patterns of expression in virgin animals and at early stage of pregnancy, from that of the BLG transgene or the endogenous mouse milk protein gene. High levels of expression (17-60% of that on day 18 of pregnancy) were detected in the mammary gland of virgin animals. At day 5 of pregnancy there was a dramatic decrease in HSA synthesis and secretion in all transgenic strains tested. The down-regulation, revealed by immunoprecipitation and immunohistochemical studies, demonstrated that at that stage of pregnancy only 10-18% of ductal structures contained HSA expressing cells in contrast to the majority of ducts expressing HSA in virgin animals. These morphological studies also demonstrated that the down-regulation in HSA synthesis and secretion was correlated with the transition from ducts comprised of a single layer of epithelial cells (characteristic of the virgin state) to ducts composed of multilayers of such cells. In two of the three transgenic strains tested, the down-regulation at the protein level was associated with a similar decrease in HSA transcripts. In the exceptional strain no. 23, HSA transcripts continued accumulating even at this stage. The differences in the control of expression at the RNA level between these transgenic strains were also confirmed by in situ hybridization. Our results suggest the involvement of at least two regulatory mechanisms effective at early stages of gestation in the control of expression/secretion of the HSA transgene targeted for expression in the mammary gland by the BLG milk protein promoter. These putative mechanisms may play key roles in the interplay between normal mammogenesis and lactogenesis. Thus, transgenic mice expressing BLG/HSA gene constructs at early stages of gestation would be valuable in further dissecting these mechanisms. © 1995 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020160304
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  • 12
    Electronic Resource
    Electronic Resource
    Phenotypic diversity of 188 rice embryo mutants (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 298-310 
    Details
    ISSN: 0192-253X
    Keywords: Embryogenesis ; rice ; mutation ; phenotypic diversity ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have identified 188 embryo mutants of rice and characterized them into six groups based on their phenotypes: (1) embryoless in mature seed, (2) deletion of embryonic organ(s), (3) abnormal position of embryonic organs, (4) abnormal embryo size, (5) defect in organ morphology, and (6) variable abnormal phenotypes in spite of single mutations. Three types of organless mutants are obtained: small globular embryo, club-shaped embryo, and large embryo. Although 12 shootless mutants derived from at least three loci are identified, only three radicleless mutants are recovered, which produce normal adventitious roots after germination. In reduced embryo mutants, every embryonic organ is reduced, in contrast to giant embryo mutants in which only scutellum is enlarged. Considerable number of mutants are categorized into (5) and (6) in the above. These diverse embryo mutants would serve as promising materials for genetic study of embryogenesis. © 1995 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020160403
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  • 13
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    Expression of knotted1 marks shoot meristem formation during maize embryogenesis (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 344-348 
    Details
    ISSN: 0192-253X
    Keywords: knotted1 ; embryogenesis ; shoot apical meristem ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The formation of shoot and root meristems that ultimately give rise to all tissues of the plant body occurs for the first time during embryogenesis. Meristem formation has traditionally been defined in terms of the appearance of histological features of meristems; this approach has led to varying interpretations of the timing of meristem formation relative to other events in embryogenesis. Markers that would provide more objective criteria for the analysis of meristem formation have not been widely available. The maize homeobox gene, knotted1 (kn1), is expressed in shoot meristems throughout postembryonic stages of shoot development. In order to determine whether this gene is expressed in the shoot meristem from its earliest inception, we examined the expression of kn1 in embryos at a series of stages by in situ hybridization to kn1 mRNA and immunolocalization of KN1 protein. Our results show that the onset of kn1 expression is temporally and spatially coincident with the earliest histologically recognizable signs of shoot meristem formation in the embryo, and thus provides a valuable marker for this process. © 1995 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/dvg.1020160407
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  • 14
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    Vertebrate gastrulation and axial patterning: Editorial overview, Part 1 (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 1-5 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020170102
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  • 15
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    Regionalisation of cell fate and morphogenetic movement of the mesoderm during mouse gastrulation (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 16-28 
    Details
    ISSN: 0192-253X
    Keywords: Mesoderm ; fate-mapping ; germ layer formation ; morphogenetic movement ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The developmental fate of cells in the epiblast of early-primitive-streak-stage mouse embryos was assessed by studying the pattern of tissue colonisation displayed by lac Z-expressing cells grafted orthotopically to nontransgenic embryos. Results of these fate-mapping experiments revealed that the lateral and posterior epiblast contain cells that will give rise predominantly to mesodermal derivatives. The various mesodermal populations are distributed in overlapping domains in the lateral and posterior epiblast, with the embryonic mesoderm such as heart, lateral, and paraxial mesoderm occupying a more distal position than the extraembryonic mesoderm. Heterotopic grafting of presumptive mesodermal cells results in the grafted cells adopting the fate appropriate to the new site, reflecting a plasticity of cell fate determination before ingression. The first wave of epiblast cells that ingress through the primitive streak are those giving rise to extraembryonic mesoderm. Cells that will form the mesoderm of the yolk sac and the amnion make up a major part of the mesodermal layer of the midprimitive-streak-stage embryo. Cells that are destined for embryonic mesoderm are still found within the epiblast, but some have been recruited to the distal portion of the mesoderm. By the late-primitive-streak-stage, the mesodermal layer contains only the precursors of embryonic mesoderm. This suggests that there has been a progressive displacement of the midstreak mesoderm to extraembryonic sites, which is reminiscent of that occurring in the overlying endodermal tissue. The regionalisation of cell fate in the late-primitive-streak mesoderm bears the same spatial relationship as their ancestors in the epiblast prior to cell ingression. This implies that both the position of the cells in the proximal-distal axis and their proximity to the primitive streak are major determinants for the patterning of the embryonic mesoderm. © 1995 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/dvg.1020170104
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  • 16
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    Cloning, sequencing, and expressional analysis of the chick homologue of follistatin (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 65-77 
    Details
    ISSN: 0192-253X
    Keywords: Follistatin ; activin ; inhibin ; chick ; rhombomeres ; somites ; resegmentation ; neural induction ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Follistatin, a secreted glycoprotein, has been shown to act as a potent neural inducer during early amphibian development. The function of this protein during embryogenesis in higher vertebrates is unclear, and to further our understanding of its role we have cloned, sequenced, and performed an in-depth expressional analysis of the chick homologue of follistatin. In addition we also describe the expression pattern of activin βA and activin β B, proteins that have previously been shown to be able to interact with follistatin. In this study we show that the expression of follistatin and the activins do not always overlap. Follistatin was first detected in Hensen's node and subsequently in the region described by Spratt [1952] as the neuralising area. In older embryos it was also expressed in a highly dynamic manner in the hind-brain as well as in the somites. We also present evidence that follistatin may have a later role in the resegmentation of the somites. We were unable to detect the expression of activin βA during early embryogenesis, whereas activin βB was first expressed in the extending primitive streak and subsequently in the neural folds. The results from this study are consistent with a role for follistatin in neural induction but suggest it has additional functions unrelated to its inhibitory actions on activins. © 1995 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/dvg.1020170108
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  • 17
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    Differential expression of fork head genes during early Xenopus and zebrafish development (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 107-116 
    Details
    ISSN: 0192-253X
    Keywords: Axis formation ; fork head ; gastrulation ; neurulation ; Xenopus ; zebrafish ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Intense efforts have been devoted to the identification of genes that are causatively involved in pattern-forming events of invertebrates and vertebrates. Several gene families involved in this process have been identified. Here we focus on the Xenopus fork head domain gene family. One of its members, XFKHl/Pintallavis/XFD1, has been shown previously to be involved in axial formation, and the expression patterns of the other family members discussed below suggest that they too play a major role in the initial steps of patterning and axial organization. In this report, we describe four Xenopus fork head genes XFKH3, 4, 5, and 6) and analyze the distribution of their transcripts during early development. XFKH3 is expressed in developing somites but not notochord, XFKH4 in forebrain, anterior retina, and neural crest cells, and XFKH5 in a subset of epidermal cells and the neural floor plate. Finally, transcripts of XFKH6 are seen in neural crest-derived cranial ganglia. In addition, we show that at least some of the zebrafish fork head genes might serve a comparable function. Zebrafish zf-FKHl has a similar expression pattern as Xenopus XFKHl/Pintallavis/XFDl. It is transcribed in the notochord and neural floor plate. The polster or “pillow” also shows very high levels of zf-FKHl mRNA. © 1995 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/dvg.1020170203
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    Epithelial proliferation and differentiation in the mammary gland do not correlate with cFABP gene expression during early pregnancy (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 167-175 
    Details
    ISSN: 0192-253X
    Keywords: Mammary gland ; fatty acid binding protein ; mammary derived growth inhibitor ; proliferation ; differentiation ; transgenic mice ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Cardiac fatty acid binding protein (cFABP) is abundantly expressed in the nondividing, functionally differentiated mammary ephithelium. It is very closely related, if not identical to, a previously described protein termed mammary derived growth inhibitor (MDGI). In vitro studies suggest that low concentrations of diffusible cFABP/MDGI may play a hormone-like role in limiting proliferative activity and promoting functional differentiation of this tissue, but no in vivo data to support this idea have been published. To test this hypothesis, we compared the levels of cFABP mRNA with both the epithelial DNA labelling index and levels of β-casein mRNA in wild-type mice. We also investigated the effect of a precocious experimental increase of cFABP levels in the mammary gland of transgenic mice on the labelling index and β-casein mRNA levels. This was accomplished by expressing a bovine cFABP cDNA under the control of the ovine β-lactoglobulin (BLG) gene promoter. We found that although both the DNA labelling index, β-casein mRNA levels, and cFABP mRNA levels in wild-type mice are developmentally regulated, they do not correlate with each other during early pregnancy in individual mice. Moreover, a three- to fourfold increase of total cFABP mRNA in two transgenic lines did not affect the DNA labelling index or the levels of β-casein mRNA, an established marker of differentiation of the mammary epithelium, at this developmental stage. These data suggest that epithelial DNA synthesis, β-casein gene expression, and expression of the cFABP gene are regulated independently in the proliferatively active mammary gland and that the rapidly dividing mammary epithelial cells are not susceptible to the action of cFABP during early pregnancy. © 1995 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/dvg.1020170208
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    Identification of genes showing altered expression in preimplantation and early postimplantation parthenogenetic embryos (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 223-232 
    Details
    ISSN: 0192-253X
    Keywords: Genomic imprinting ; parthenogenetic embryos ; biallelic expression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Uniparental embryos have been instrumental in studying imprinting because contributions from the parental genomes can be determined unambiguously. In this study, we set out to identify imprinted genes showing differential expression between parthenogenetic and fertilized embryos during preimplantation and early postimplantation stages of development. We identified three genes-apolipoprotein E, pyruvate kinase-3, and protein phosphatase 1 gamma-that represent excellent candidates for imprinted genes, based on the results of the differential screen, their function in differentiation and the cell cycle, and their location within imprinted chromosomal regions. In addition, two novel genes expressed in trophoblast were identified, 1661 and RA81. These genes, together with four known imprinted genes, H19, Igf2r, Igf2, and Snrpn, showed evidence of expression from both parental alleles in early stage embryos, indicating a role for postfertilization processes in regulating imprinted gene function. © 1995 Wiley-Liss, Inc.
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    Parent-of-origin specific effects on the methylation of a transgene in the zebrafish, Danio rerio (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 233-239 
    Details
    ISSN: 0192-253X
    Keywords: Genome imprinting ; zebrafish ; Danio rerio ; methylation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have examined the inheritance of a transgene locus in the zebrafish, Daniorerio and demonstrated that its methylation is af fected by the sex of the parent contributing the allele. This parent-of-origin effect on the zebrafish transgene appears to be identical to imprinting as seen in mammals except that in zebrafish, passage of the locus through a female tended to decreased its methylation, whereas passage through a male increased it. Methylation of the transgene in gametic tissues differed from somatic tissue with the locus being hypomethylated in sperm and hypermethylated in the unfertilized egg. The potential identification of imprinting in the zebrafish has important ramifications with respect to the evolution of the process as well as for understanding the role of imprinting in mammals. © 1995 Wiley-Liss, Inc.
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    Differential amplification of pheromone genes of the ciliate Euplotes raikovi (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 272-279 
    Details
    ISSN: 0192-253X
    Keywords: Gene amplification ; hypotrichous ciliates ; macronuclear genes ; gene expression ; recognition factors ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In hypotrich ciliates, the entire silent chromosomal genome of the germinal nucleus (micronucleus) undergoes extensive DNA rearrangements that, during the development of the somatic nucleus (macronucleus) at the beginning a new cell life cycle, eventually result in the production of linear DNA molecules. These molecules represent functional genes, each one consisting of a central coding region flanked by two shorter regions, which apparently lack canonical elements for regulation of replication and transcription. These are amplified to thousands of copies in the “adult” macronucleus of the vegetative cell. We defined the extent of this amplification for allelic codominant genes which, in the macronucleus of Euplotes raikovi, encode polypeptide cell recognition factors (pheromones). This amplification was shown to be allele-specific. The copy numbers of genes coding for pheromones Er-1, Er-2, and Er-10 were determined to be 2.5 - 2.9 × 104, 0.9 - 1.2 × 104, 1.6 - 1.85 × 104 respectively, and these numbers did not appreciably vary during the vegetative cell proliferation. This differential amplification of pheromone genes was (i) independent of whether two genes coexisted in the same heterozy-gous cell or were separated in the corresponding homozygotes, and (ii) directly correlated with quantitative variations in mRNA synthesis and pheromone secretion. On the basis of these results, it is suggested that a mechanism of gene-specific amplification may be used by hypotrich ciliates to modulate gene expression. © 1995 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/dvg.1020170312
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    Imprinting of IGF2, insulin-dependent diabetes, immune function, and apoptosis: A hypothesis (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 253-262 
    Details
    ISSN: 0192-253X
    Keywords: IGF2 ; IDDM2 ; IDDM ; immune function ; IGFs ; apoptosis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Parental genomic imprinting is the phenomenon in which the behavior of a gene is modified, depending on the sex of the transmitting parent [Peterson and Sapienza (1993): Annu Rev Genet 27:7-31]. Recent observations have revealed that the inheritance patterns, age-of-onset, severity, and etiology of certain human diseases can be explained by aberrations in the establishment or the maintenance of the imprint. Examples include the Prader-Willi, Angelman, and Beckwith-Wiedemann syndromes [Nicholls (1994): Am J Hum Genet 54:733-740], malignancy [Sapienza (1990): Biochim Biophys Acta 1072:51-61; Feinberg (1993): Nat Genet 4:110-113], and insulin-ependent diabetes mellitus (IDDM) [Julier et al. (1994) Nature 354:155-159; Bennett et al. (1995) Nat Genet 9:284-292]. We review the evidence that implicates an imprinted gene in the INS-IGF2 region of chromosome llp15 in the etiology of IDDM (referred to as the IDDM2 locus) and show that in human fetal pancreas, INS is not imprinted, thus providing an argument against INS as the candidate gene. We also examine imprinting effects on the expression of IGF2 in components of the human immune system believed to be important in IDDM and show imprinted expression in fetal thymus as early as 15 weeks gestation. We demonstrate further that in the circulating mononuclear cells of two individuals, lectin-stimulated IGF2 transcription was biallelic, indicating relaxation of imprinting, whereas in one individual, transcription was monoallelic. Finally, we review the current available data supporting a role for insulin-like growth factor-ll (IGF-II) in the immune system and, more specifically, discuss the evidence supporting a role for the IGFs in the prevention of apoptosis. These data have led us to formulate a novel hypothesis that could mechanistically explain the involvement of the IDDM2 locus in the pathogenesis of IDDM. © 1995 Wiley-Liss, Inc.
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    A Xenopus laevis gene encoding EF-1αS, the somatic form of elongation factor 1α: Sequence, structure, and identification of regulatory elements required for embryonic transcription (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 280-290 
    Details
    ISSN: 0192-253X
    Keywords: Translation elongation factor 1α (EF-1α) ; developmental regulation ; oogenesis ; microinjection ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Transcription of the Xenopus laevis EF-1αS gene commences at the mid-blastula stage of embryonic development and then continues constitutively in all somatic tissues. The EF-1αS promoter is extremely active in the early Xenopus embryo where EF-1αS transcripts account for as much as 40% of all new polyadenylated transcripts. We have isolated the Xenopus EF-1αS gene and used microinjection techniques to identify promoter elements responsible for embryonic transcription. These in vivo expression studies have identified an enhancer fragment, located approximately 4.4 kb upstream of the transcription start site, that is required for maximum expression from the EF-1αS promoter. The enhancer fragment contains both an octamer and a G/C box sequence, but mutation studies indicate that the octamer plays no significant role in regulation of EF-1αS expression in the embryo. The presence of a G/C element in the enhancer and of multiple G/C boxes in the proximal promoter region suggests that the G/C box binding protein, Spl, plays a major role in the developmental regulation of EF-1αS promoter activity. © 1995 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/dvg.1020170313
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    Cloning and developmental expression of the ecdysone receptor gene from the spruce budworm, choristoneura fumiferana (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 319-330 
    Details
    ISSN: 0192-253X
    Keywords: Ecdysone receptor ; Choristoneura fumiferana cDNA cloning ; developmental expression ; molting and metamorphosis ; ecdysone response element ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Degenerate oligonucleotides were designed on the basis of conserved amino acid sequences in the DNA and ligand-binding regions of the members of the steroid hormone receptor superfamily. Using these oligonucleotides in RNA-PCR, a cDNA fragment was isolated from the spruce budworm, Choristoneura fumiferana. Comparison of the deduced amino acid sequence of this cDNA fragment with the members of the steroid hormone receptor superfamily suggested that this PCR fragment is a region of the ecdysone receptor from C. fumiferana. Using this cDNA fragment as a probe, 10 clones were isolated from a cDNA library that was constructed using the RNA from 4- and 5-day old embryos of C. fumiferana. Two cDNA clones (1.3 and 3 kb) that overlap and show amino acid identity with Drosophila melanogaster ecdysone receptor B-1 isoform (DmEcR) were characterized and sequenced. The longest open reading frame had 539 codons and covered the complete EcR coding region. The deduced amino acid sequence of this open reading frame had all five of the regions typical for a steroid hormone nuclear receptor. The C domain or DNA binding region showed the highest identity with EcR proteins from D. melanogaster, Chironomus tentans, Aedes aegypti, Manduca sexta and Bombyx mori. The A/B region, D domain or hinge region, E domain, or ligand binding region also showed significant amino acid similarity with the EcR proteins from the five insects mentioned above. The C. fumiferana ecdysteroid receptor (CfEcR) cDNA probe detected a 6.0-kb mRNA that was present throughout the development of C. fumiferana. The CfEcR mRNA increases in abundance at the time of the ecdysteroid peak during the molting phase in the embryonic, larval and pupal stages but remains low during the intermolt period. In the 6th instar larvae, the 6-kb CfEcR mRNA was detected in the epidermis, fat body, and midgut and maximum expression was observed during the prepupal peak of ecdysteroids in the hemolymph. CfEcR mRNA was induced in ecdysone treated CF-203 cells as well as in the epidermis and midgut of larvae that were fed the nonsteroidal ecdysteroid agonist, RH-5992. The induction occurred within an hour and reached maximum levels around 3 hr, after which it decreased to the basal level by 6 hr. In vitro transcription and translation of the CfEcR cDNA yielded a 67-Kda protein that bound to the ecdysone response element (EcRE) as a heterodimer, along with the ultraspiracle protein.
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    Editorial announcement (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. i 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020160102
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    Unusual cytoskeletal and chromatin configurations in mouse oocytes that are atypical in meiotic progression (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 13-19 
    Details
    ISSN: 0192-253X
    Keywords: Meiotic maturation ; chromatin ; centrosomes ; microtubules ; oocytes ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Meiotic maturation progresses atypically in oocytes of strain LT/Sv and l/LnJ mice. LT/Sv occytes show a high frequency of metaphase l-arrest and parthenogenetic activation. l/LnJ oocytes display retarded kinetics of meiotic maturation and a high frequency of metaphase l-arrest. Some l/LnJ oocytes fail to resume meiosis. Changes in the configuration of chromatin, microtubules, and centrosomes are associated with specific stages of meiotic progression. In this study, the configuration of these subcellular components was examined in LT/Sv, l/LnJ, and C57BL/6J (control) oocytes either freshly isolated from large antral follicles or after culture for 15 hr to allow progression of spontaneous meiotic maturation. Differences were found in the organization of chromatin, microtubules, and centrosomes in LT/Sv and l/LnJ oocytes compared to control oocytes. For example, rather than exhibiting multiple cytoplasmic and nuclear centrosomes as in the normal germinal vesicle-stage oocytes, LT/Sv oocytes typically contain a single large centrosome. In contrast, l/LnJ oocytes displayed many small centrosomes. The microtubules of normal germinal vesicle-stage oocytes were organized as arrays or asters, but microtubules were shorter in LT/Sv oocytes and absent from l/LnJ oocytes. After a 15-hr culture, centrosomal material of normal metaphase II oocytes was organized at both spindle poles. In contrast, metaphase l-arrested LT/Sv oocytes exhibited an elongated spindle with centrosomal material appearing more organized at one pole of the spindle. Both control and LT/Sv oocytes displayed cytoplasmic centrosomes. Metaphase l-arrested l/LnJ oocytes rarely had cytoplasmic centrosomes but exhibited centrosomal foci at the spindle periphery. Thus, oocytes that are atypical in the progression of meiotic maturation displayed aberrant configurations of microtubules and centrosomes, which are thought to participate in the regulation of meiotic maturation.
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    Epidermal cell-specific quantitation of dopa decarboxylase mRNA in Drosophila by competitive RT-PCR: An effect of Broad-Complex mutants (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 77-84 
    Details
    ISSN: 0192-253X
    Keywords: Ecdysone ; Dopa decarboxylase ; Drosophila melanogaster ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The quontitation of RNA in tissue homogenates by amplifying the product of reverse transcription (RT-PCR) is sufficiently sensitive to detect molecules in the range of 10-110-2 amole. We describe here the steps we believe necessary to validate a protocal that used a DNA competitor and visualization of the amplification products by ethidium bromide staining. The procedure was designed to quantitate one of the tissue specific transcripts of the Dopa decarboxylase gene (Ddc) in Drosophila. We demonstrate that the amount of epidermal Ddc transcript is much lower at pupariation in several mutants of the Broad-Complex, one of the primary response loci of the moulting hormone, ecdysone. The mutant effects were allele specific and the molecular basis of one of these alleles is known. This implicates a particular family of the zinc finger proteins encoded by the locus in the hormone dependent induction of Ddc expression.
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    Biochemical analysis of programmed cell death during premeiotic stages of spermatogenesis in vivo and in vitro (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 140-147 
    Details
    ISSN: 0192-253X
    Keywords: Programmed cell death ; apoptosis ; spermatogenesis ; premeiotic stages ; testis ; in vitro regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Control points of regulator action during spermatogenesis are not completely known. Using the shark testis model, which facilitates analysis of spermatogenesis stage-by-stage in vivo and in vitro, an early biochemical marker of programmed cell death (PCD) was detected. Nucleosomal oligomers were seen in DNA extracts of testis and isolated spermatocysts (clonal germ cell/ Sertoli cell units) at premeiotic (PrM), but not meiotic (M) or postmeiotic (PoM), stages. Cell nuclei isolated from M stages of development were susceptible to cleavage by micrococcal nuclease, suggesting that developmental control of factors other than a nuclease-insensitive chromatin structure may account for stage specificity. Cytological features of apoptosis were seen in germ cells, but not Sertoli cells, of a subset of isolated PrM spermatocysts and appeared to be all-or-none in affected clones. In culture, DNA fragmentation occurred on schedule with or without various additives, but the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) decreased accumulation of DNA breakdown products. Identification of the apoptotic form of PCD as a major, variable component of normal spermatogenesis and the use of PrM spermatocysts as an in vitro test system will allow further definition of mechanisms and developmental and physiological controls. © 1995 Wiley-Liss, Inc.
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    Masthead (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995) 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020160301
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    Positive and negative feedback loops affect the transcription of IME1, a positive regulator of meiosis in Saccharomyces cerevisiae (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 219-228 
    Details
    ISSN: 0192-253X
    Keywords: IME1 ; Meiosis ; Transcriptional regulation ; S. cerevisiae ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The IME1 gene of Saccharomyces cerevisiae encodes a transcription factor that is required for the expression of meiosis-specific genes. Like many of the genes it regulates, IME1 itself is expressed according to the following complex pattern: barely detectable levels during vegetative growth, and high induced levels under starvation conditions, followed by a subsequent decline in the course of meiosis. This report examines the influence of Ime1 protein on its own expression, demonstrating feedback regulation. Disruption of either IME1 or IME2 leads to constantly increasing levels of Ime1-lacZ expression, under meiotic conditions. This apparent negative regulation is due to cis elements in the IME1 upstream region, which confer transient meiotic expression to heterologous promoter-less genes. A specific DNA/protein complex, whose level is transiently increased under meiotic conditions, is detected on this element. In ime1- diploids, the level of this DNA/protein complex increases, without any decline. These results indicate that the transient expression of IME1 is apparently due to transcriptional regulation. This report also presents evidence suggesting that Ime 1p is directly responsible for regulating its own transcription. Positive feedback regulation in mitotic conditions is suggested by the observation that overexpression of Ime 1p leads to increased levels of IME1-lacZ. Negative autoregulation in meiotic cultures is demonstrated by the observation that a specific point mutation in IME1, ime 1-3, permits expression of meiosis-specific genes, as well as induction of meiosis, but is defective in negative-feedback regulation of IME1. © 1995 Wiley-Liss, Inc.
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    Genetic mosaic analysis of the equatorial-less mutation in Drosophila mezunogaster (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 264-272 
    Details
    ISSN: 0192-253X
    Keywords: Equatorial-less ; compound eye ; genetic mosaics ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: eql (equatorial-less) is a recessive lethal mutation on the second chromosome of Drosophila melanogasfer. J. Campos-Ortega found that eql clones in somatic mosaic flies have reduced numbers of photoreceptor cells, and he suggested that only the R1, R6, and R7 photoreceptor cells were missing in this mutant. These photoreceptor cells help to define the inverted orientation of ommatidial facets along the equatorial midline of the fly eye, hence the mutation was named “equatorial-less”. We have conducted a detailed analysis of the eql mutation, by serial section reconstruction of eql clones marked with bw or w- in somatic mosaic flies. We found that all photoreceptor cell types (Rl-R8) could be deleted by the eql mutation, and in rare cases the number of photoreceptor cells was increased. The apparent lack of photoreceptor cell type specificity was confirmed by our analysis of genetically mosaic facets, which indicated that no single photoreceptor cell, or subset of photoreceptor cells, was uniquely required to express eql Rather, eql appears to function in all photoreceptor cells, and possibly in all eye precursor cells. The distribution of photoreceptor cell numbers in w eql facets was consistent with the hypothesis that each photoreceptor cell was deleted independently of the others. The eql gene is located on the right arm of chromosome 2 at map location 2 - 104.5 ± 0.7 and lies between the polytene chromosome bands 59D8 and 60A7. © 1995 Wiley-Liss, Inc.
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    Embryonic regulation of histone ubiquitination the sea urchin (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 278-290 
    Details
    ISSN: 0192-253X
    Keywords: Histone variants ; gene expression ; histone ubiquitination ; H2A ; H2B ; H3 ; sea urchin ; embryogenesis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have used quantitative 2-D protein electrophoresis and immunoprecipitation to study the patterns of histone ubiquitination at 10 h and 36 h of embryonic development in Strongylocentrotus purpuratus. Variants csH2A, αH2A, βH2A, γH2A, δHA, H2AF./Z, αH2B, βH2B, and γH2B showed up to sevenfold differences in level of monoubiquitination between variants, and individual variants showed up to sixfold changes during development. At 36 h of embryogenesis, the late variants were less ubiquitinated than the early variants, althoug h the overall level of ubiquitination was appreciably greater than at 10 h. Antiubiquitin antibodies were used to precipitate formaldehyde-fixed chromatin fragments in order to estimate the degree of ubiquitination of the early histone genes. The 5′ regulatory region of the active H3 gene appeared to be at least twice as ubiquitinated as the adjacent upstream spacer. However, the absolute level of ubiquitination of the early histone gene repeat seemed to be independent of transcriptional activity. These results show that variant-specific ubiquitination of histones is a part of the developmental program in sea urchin embryos, but is not clearly correlated with transcriptional activity of the early histone genes, except perhaps in the regulatory regions. © 1995 Wiley-Liss, Inc.
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    Transient reduction in secreted 32 kD chitinase prevents somatic embryogenesis in the carrot (Daucus carota L.) variant ts11 (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 332-343 
    Details
    ISSN: 0192-253X
    Keywords: Somatic embryogenesis ; temperature-sensitive mutant ts11 ; chitinase ; carrot (Daucus carota L.) ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: At the nonpermissive temperature, somatic embryos of the temperature-sensitive (ts) carrot (Daucus carota L.) cell variant ts11 only proceed beyond the globular embryo stage in the presence of medium conditioned by wild-type cells. The causative component in the conditioned medium has been identified as an acidic 32 kD endochitinase. An antiserum raised against the 32 kD chitinase detected this protein in culture medium from ts11 embryo cultures grown at the permissive temperature as well as at the nonpermissive temperature. No difference in biochemical characteristics or in effect on ts11 embryo development could be detected between the 32 kD chitinase purified from wild-type cultures and the chitinase from ts11 cultures grown at the permissive or at the nonpermissive temperature. Compared to the amount present in a ts11 embryo culture at the permissive temperature, a reduction in the amount of 32 kD chitinase was observed during the temperature-sensitive period at the nonpermissive temperature. These results imply that the arrested embryo phenotype of ts11 is not the result of a structural difference in its 32 kD chitinase, but is the result of a transient decrease in the amount of 32 kD chitinase present. Morphological observations indicate that the ts11 phenotype is pleiotropic and also affects the cell wall of nonembryogenic cells. © 1995 Wiley-Liss, Inc.
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    Cell mixing during early epiboly in the zebrafish embryo (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 6-15 
    Details
    ISSN: 0192-253X
    Keywords: Zebrafish ; epiboly ; gastrulation ; radial intercalation ; cell mixing ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Descendants of early blastomeres in the zebrafish come to populate distinctive regions of the fate map. We present a model suggesting that the distribution of cells in the early gastrula (the fate map stage) results from the passive response of cells to reproducible forces that change the overall shape of the blastoderm just prior to gastrulation. We suggest that one of the morphogenetic changes that accompanies epiboly, the upward doming of the yolk cell into the overlying blastoderm, could be responsible for cell mixing. In support of the model, we show that the timing, extent, and directions of cell mixing in the embryo accurately reflect the expectations of the model. Finally, we show that one portion of the gastrula, a marginal region that later gives rise to many of the mesendodermal derivatives, experiences little cell mixing during the doming process. As a result, this region in the gastrula is populated by the descendants of the subset of the early blastomeres that were originally at the margin. The finding that cytoplasm initially at the edge of the 1-celled blastodisc is transmitted specifically to mesendodermal precursors at the fate map stage raises the possibility that maternal determinants may contribute to initiation of embryonic patterning in the zebrafish embryo. © 1995 Wiley-Liss, Inc.
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    Translational control of activin in Xenopus laevis embryos (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 55-64 
    Details
    ISSN: 0192-253X
    Keywords: Translational control ; activin ; Xenopus ; mesoderm induction ; embryo ; TGF-ß ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Activin is a potent mesoderm inducing factor present in embryos of Xenopus laevis. Recent evidence has implicated activin in the inhibition of neural development in addition to the well-established induction of mesoderm in ectodermal explants. These diverse effects are critically dependent on the concentration of activin yet little is known about the mechanisms regulating the level of activin in the embryo. We report that the 3′ untranslated region (3′ UTR) of activin βB mRNA inhibits the translation of activin in embryos. Microinjection of activin mRNA from which the 3′ UTR has been deleted is 8-10-fold more potent in inducing mesoderm than mRNA containing the 3′ UTR. Truncation of the 3′ UTR also leads to a marked enhancement of activin protein levels in embryos but has no effect when the truncated mRNA is translated in vitro. The 3′ UTR also confers translational inhibition on a heterologous mRNA. These data show that a maternal factor(s) present in X. laevis regulates the translation of injected activin βB mRNA. This factor(s) could be responsible for regulating the levels of endogenous activin βB protein during mesoderm induction and the specification of ectodermal derivatives such as neural and epidermal tissues. © 1995 Wiley-Liss, Inc.
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    Vertebrate gastrulation and axial patterning: Editorial overview, Part 2 (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 103-106 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020170202
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    Involvement of Wnt1 and Pax2 in the formation of the midbrain-hindbrain boundary in the zebrafish gastrula (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 129-140 
    Details
    ISSN: 0192-253X
    Keywords: Zebrafish ; Danio rerio ; wnt ; pax ; embryogenesis ; neurulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The secreted signalling molecule encoded by the wntl gene and the paired box-containing pax2 gene are thought to play an integral role in patterning the zebrafish rostral nervous system. Using a double-label analysis, we compare the expression patterns of wnt1 RNA and pax2 protein during zebrafish embryogenesis to determine whether they were expressed in identical or overlapping patterns in individual embryos. During gastrulation, wntl RNA was detected in a pattern similar but not identical to the pax2 protein. Later, wntl and pax2 co-localize to the midbrain-hindbrain boundary. Exogenous retinoic acid, a teratogen that is known to affect the formation of the midbrain-hindbrain boundary, has a profound affect on both wntl and pax2 expression at gastrulation. Furthermore, when pax2 is overexpressed in zebrafish embryos, the wntl pattern of expression expands ventrally in the prospective rostral neuroepithelium. Despite the widespread and random distribution of exogenous pax2 RNA, it alone is unable to induce wntl expression in other ec-topic sites. These results are consistent with the coordinate expression of wntl and pax2 being in a pathway responsible for establishing the midbrain-hindbrain boundary and support the earlier interpretation that pax2 may regulate wntl expression [Krauss et al., 1992], although only in a subset of embryonic cells. These data suggest that a predisposition for the regionalization of the central nervous system exists at gastrulation. © 1995 Wiley-Liss, Inc.
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    Genome imprinting: An overview (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 185-187 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020170302
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    Genetic conflict and evolution of mammalian X-chromosome inactivation (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 206-211 
    Details
    ISSN: 0192-253X
    Keywords: Genetic conflict ; parent-offspring conflict ; X-chromosome inactivation ; parental imprinting ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The existence of parentally imprinted gene expression in the somatic tissues of mammals and plants can be explained by a theory of intragenomic genetic conflict, which is a logical extension of classical parent-offspring conflict theory. This theory unites conceptually the phenomena of autosomal imprinting and X-chromosome inactivation. We argue that recent experimental studies of X-chromosome inactivation and andro-genetic development address previously published predictions of the conflict theory, and we discuss possible explanations for the occurrence of random X-inactivation in the somatic tissues of eutherians. © 1995 Wiley-Liss, Inc.
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    Expression of SGP-1 mRNA in preimplantation mouse embryos (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 263-271 
    Details
    ISSN: 0192-253X
    Keywords: Mouse embryos ; SGP-1 mRNA ; antisense ; gene transcription ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In a search for genes expressed in preimplantation mouse embryos that are important for the earliest steps in differentiation, we identified an abundant mRNA that codes for a sulfated glycoprotein, SGP-1. The amount of this RNA rises ˜ 100-fold during preimplantation development to a level approximately equal to that of β-actin mRNA in blastocysts, although the level of these transcripts per cell remains fairly constant during these stages at ˜ 2,000-4,000 copies. An antisense RNA that is complementary to approximately the last one-third of the message and contains an open reading frame of 455 nt was found in blastocysts at a 2-3-fold higher level than the mRNA. In situ hybridization with sense and antisense riboprobes showed that both strands are distributed throughout the embryo. The abundance of the SGP-1 mRNA indicates that the encoded protein may play an important role in the development of embryos, and the excess of antisense RNA raises the possibility of an unusual mechanism of regulating its expression. © 1995 Wiley-Liss, Inc.
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    Two isoforms of xenopus retinoic acid receptor γ2 (B) exhibit differential expression and sensitivity to retinoic acid during embryogenesis (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 291-302 
    Details
    ISSN: 0192-253X
    Keywords: Retinoic acid receptors ; retinoic acid ; Xenopus ; CNS ; pattern formation ; ultraviolet ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We report the isolation of two retinoic acid receptor isoforms (RARγ), which differ only in the 5′ untranslated and putative N-terminus A regions. The two isoforms appear to serve as early markers for the presumptive neural axis; however, their expression patterns differ. RARγ2, 1 is first expressed at gastrulation at the dorsal lip and subsequently along the presumptive neural axis. RARγ2.2 represents the full-length sequence of a receptor cDNA already partially characterized and present as a maternal transcript [Ellinger-Ziegelbauer and Dreyer (1991); Genes Dev 5:94-104, (1993): Mech Dev 41:31-46; Pfeffer and DeRobertis, (1994) Mech Dev: 45:147-153]. Unlike RARγ2.2, the 2.1 variant is not expressed either in pre-somitic mesoderm or notochord. RARγ2.1 is strongly expressed in branchial arches and to a lesser extent in the neural floor plate. The two isoforms also exhibit differential sensitivity to retinoic acid. Constitutive expression of RARγ2.2 following neurulation appears to be depressed by treatment with retinoic acid, but domains of highest expression, namely, the head and tail, remain relatively unaffected, as do patterns of expression prior to late neurulation. By contrast, RARγ2.1 is not transcribed in retinoid-inhibited structures. Using microinjection techniques, we show that changes of RARγ2.1 expression in presumptive head structures occur as an early and local consequence of retinoic acid administration. Since RARγ2.1 expression is inhibited by retinoic acid, we tested to see if other treatments that perturb axis formation had any effect. Surprisingly, UV irradiation did not suppress expression of the RARγ2.1 transcript, suggesting that its inhibition by retinoic acid is not due solely to inhibition of anterior neural development. These experiments demonstrate a new subdivision of isoforms that undergo differential expression during development and that exhibit differential sensitivity to retinoic acid and to UV. This sensitivity and the presence of this isoform variant in regions that are known to exhibit polarizing activity strengthen the hypothesis that these receptors play a primary role during morphogenesis.
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    Identification of members of the HSP30 small heat shock protein family and characterization of their developmental regulation in heat-shocked xenopus laevis embryos (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 331-339 
    Details
    ISSN: 0192-253X
    Keywords: Xenopus laevis ; heat shock protein ; HSP 30 ; developmental gene expression ; translation ; immunoblotting ; microinjection ; embryos ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In the present study we have characterized the synthesis of members of the HSP30 family during Xenopus laevis development using a polyclonal antipeptide antibody derived from the carboxyl end of HSP30C. Two-dimensional PAGE/immunoblot analysis was unable to detect any heat-inducible small HSPs in cleavage, blastula, gastrula, or neurula stage embryos. However, heat-inducible accumulation of a single protein was first detectable in early tailbud embryos with an additional 5 HSPs at the late tailbud stage and a total of 13 small HSPs at the early tadpole stage. In the Xenopus A6 kidney epithelial cell line, a total of eight heat-inducible small HSPs were detected by this antibody. Comparison of the pattern of protein synthesis in embryos and somatic cells revealed a number of common and unique heat inducible proteins in Xenopus embryos and cultured kidney epithelial cells. To specifically identify the protein product of the HSP30C gene, we made a chimeric gene construct with the Xenopus HSP30C coding sequence under the control of a constitutive promoter. This construct was microinjected into fertilized eggs and resulted in the premature and constitutive synthesis of the HSP30C protein in gastrula stage embryos. Through a series of mixing experiments, we were able to specifically identify the protein encoded by the HSP30C gene in embryos and somatic cells and to conclude that HSP30C synthesis was first heat-inducible at the early tailbud stage of development. The differential pattern of heat-inducible accumulation of members of the HSP30 family during Xenopus development suggests that these proteins may have distinct functions at specific embryonic stages during a stress response.
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    Cell interactions in testis development: Overexpression of c-mos in spermatocytes leads to increased germ cell proliferation (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 190-200 
    Details
    ISSN: 0192-253X
    Keywords: c-mos ; testis development ; transgenics ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Possible functions of the c-mos proto-oncogene during spermotogenesis were investigated through perturbations of its expression in transgenic mice. Two promoters, one from the pre-meiotic male germ cell-specific mouse phosphoglycerate kinase 2 gene, and the other from the post-meiotic male germ cell-specific rat RT7 gene were used to direct expression of c-mos.Northern blot analysis of testis RNA from transgenic PGK-c-mos mice indicated elevated levels of c-mos RNA in spermatocytes and spermatids compared to controls. No transgene expression was detected in any other tissue examined, suggesting that the mouse PGK2 promoter, like the previously used human PGK2 promoter, confers correct cell-specific expression onto c-mos.The promoter from a newly characterized rat gene, RT7, was shown to direct expression specific to post-meiotic spermatids. Transgenic mice carrying an RT7-lacZ construct displayed immunoreactive bacterial β-galactosidase as well as enzyme activity in round spermatids. The cellular specificity for β-galactosidase expression observed in RT7-lacZ transgenic animals was in agreement with endogenous RT7 transcript expression. Northern blot analysis of testis RNA of RT7-c-mos transgenic mice showed elevated levels of c-mos in spermatids, but not in other cells or tissues examined.Western blot analysis demonstrated elevated levels of p43c-mos in spermatids of both PGK-c-mos and RT7-c-mos transgenic animals, but only PGK-c-mos transgenics had increased p43cc-mos levels in spermatocytes. Both RT7-c-mos and PGK-c-mos transgenic mice are fertile and show no tendency toward transformation. RT7-c-mos mice have no discernible phenotype associated with the c-mos overexpression in spermatids. However, PGK-c-mos transgenic males exhibited a significant increase in germ cell number, as determined by cell counts using total germ cells and germ cells fractionated by centrifugal elutriation. Because mitotic divisions of germ cells occur prior to PGK-c-mos transgene expression, our observations suggest that c-mos overexpression in spermatocytes causes an alteration in cell-cell interactions. © 1995 Wiley-Liss, Inc.
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    Evaluation of an antisense RNA transgene for inhibiting growth hormone gene expression in transgenic rats (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 273-277 
    Details
    ISSN: 0192-253X
    Keywords: Antisense RNA ; thyroid response element ; homozygosity ; heterozygosity ; growth hormone gene ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We compared the levels of growth hormone (GH) mRNA in the pituitary, plasma GH concentration, and altered phenotype in rats heterozygous and homozygous for an antisense RNA transgene targeted to the rat GH gene, with those in nontransgenic rats. We initially investigated whether the transgene promoter, which is connected to four copies of a thyroid hormone response element (TRE) that increases promoter activity, affected in vivo transgene expression in the pituitary of the transgenic rats. Plasma GH concentration correlated negatively with T, injection in surgically thyroidectomized heterozygous transgenic rats. There was a reduction of about ˜35-40% in GH mRNA levels in the pituitary of homozygous animals compared with those in non-transgenic rats. Plasma GH concentration was significantly ˜25-32 and ˜29-41% lower in heterozygous and homozygous transgenic rats, respectively, compared with that in nontransgenic animals. Furthermore, the growth rates in homozygous transgenic rats were reduced by ˜72-81 and ˜51-70% compared with those of their heterozygous and nontransgenic littermates, respectively. The results of these studies suggested that the biological effect of GH in vivo is modulated dose-dependently by the antisense RNA transgene. The rat GH gene can therefore be targeted by antisense RNA produced from a transgene, as reflected in the protein and RNA levels. © 1995 Wiley-Liss, Inc.
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    cyd, a mutant of pea that alters embryo morphology is defective in cytokinesis (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 321-331 
    Details
    ISSN: 0192-253X
    Keywords: Caffeine ; cytokinesis ; development ; embryogenesis ; mutant ; pattern formation ; pea ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Embryogenesis in higher plants requires the precise regulation of cell division, orientation of cell elongation and specification of cell differentiation. The division plane is determined by the position of a new cell plate at cytokinesis. A mutant of pea has been isolated in which both the embryo pattern and surface morphology is altered. The phenotype of the mutant is manifest primarily in the cotyledons where cell plates only partially form, generating cell wall stubs and multinucleate cells. Some cotyledonary cells of the mutant proceed through nine DNA replication cycles, including nuclear division, but not cytokinesis, producing nuclei with a DNA content of ca. 1000C. The cytological phenotype of the mutant could be mimicked by the treatment of wild-type cells with caffeine. We have termed this mutant cytokinesis-defective (cyd). © 1995 Wiley-Liss, Inc.
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    Effect of mutations in the PINHEAD gene of Arabidopsis on the formation of shoot apical meristems (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 358-366 
    Details
    ISSN: 0192-253X
    Keywords: PINHEAD ; Arabidopsis ; shoot apical meristems ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The primary shoot apical meristem of angiosperm plants is formed during embryogenesis. Lateral shoot apical meristems arise postembryonically in the axils of leaves. Recessive mutations at the PINHEAD locus of Arabidopsis interfere with the ability of both the primary shoot apical meristem as well as lateral shoot apical meristems to form. However, adventitious shoot apical meristems can form in pinhead mutant seedlings from the axils of the cotyledons and also from cultred root explants. In this report, the phenotype of pinhead mutants is described, and a hypothesis for the role of the wild-type PINHEAD gene product in shoot meristem initiation is presented. © 1995 Wiley-Liss, Inc.
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    Developmental progression of Gpd expression from the inactive X chromosome of the virginia opossum (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 367-374 
    Details
    ISSN: 0192-253X
    Keywords: X-chromosome inactivation ; Gpd expression ; marsupial ; development ; opossum ; triplaid ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Metatherian (marsupial) mammals possess a non-random form of X-chromosome inactivation in which the paternally-derived X is always the one inactivated. To examine the progression of X-linked gene expression during metatherian development, we compared relative levels of the maternally and paternally encoded Gpd gene products in heterozygous female Virginia opossums (Didelphis virginiana) across a moior portion of the developmental period. Panels of tissues obtained from fetuses, newborns, and pouch young were examined via polyacrylamide gel electrophoresis of the G6PD protein. As in adults, G6PD phenotypes in these developmental stages were highly skewed in favor of the maternal allele product, but in some tissues there was a marked increase in paternal allele expression with advancing developmental age. However, even by 42 days of post-partum development, expression of the paternal Gpd allele had not attained the adult, tissue-specific activity pattern. Our findings indicate remarkable developmental changes in the activity of the paternal allele in several tissues/organs continuing well into mid pouch-life stages and beyond. Specifically we found that 1) a substantially repressed paternal Gpdgene is present in the cells of female stage 29 fetuses and later developmental stages, 2) the activity state of the paternal Gpd gene is not fixed during early embryonic development in this species, 3) maior changes in paternal Gpd expression occur in advanced developmental stages and comprise a maturation of the gene expression pattern during ontogeny, and 4) alterations of paternal Gpd allele activity during development occur in a tissue-specific manner. © 1995 Wiley-Liss, Inc.
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    Mesodermal patterning during avian gastrulation and neurulation: Experimental induction of notochord from non-notochordal precursor cells (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 38-54 
    Details
    ISSN: 0192-253X
    Keywords: Endoderm ; epiblast ; mesoderm ; neural plate ; quail/chick chimeras ; somites ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The cells that are normally fated to form notochord occupy a region at the rostral tip of the primitive streak at late gastrula/early neurula stages of avian and mammalian development. If these cells are surgically removed from avian embryos in culture, a notochord will nonetheless form in the majority of cases. The origin of this reconstituted notochord previously had not been investigated and was the objective of this study. Chick embryos at late gastrulal early neurula stages were cultured, and the rostral tip of the primitive streak including Hensen's node was removed and replaced with non-node cells from quail epiblast to ensure that the cells normally fated to be notochord would be absent and that healing of the blastoderm would occur. Embryos were allowed to develop for 24 hr, and the presence and origin (host or graft) of the notochord were assessed using antibodies against notochord or quail cells. Two notochords typically developed; both were almost exclusively of host origin. The primitive streak, and in some cases adjacent tissues, was removed from another group of embryos in an attempt to estimate the mediolateral position and extent of the cells required to form reconstituted notochord. Additional experimental embryos with and without grafts were transected at various rostrocaudal levels in an attempt to estimate the rostrocaudal extent of the cells required to form reconstituted notochord. Finally, various levels of the primitive streak either were placed in a neutral environment (the germ cell crescent) or were grafted in place of the node. Collective results from all experiments indicate that the areas lateral to the rostral portion of the primitive streak, estimated to have a rostrocaudal span of less than 500 μm and a mediolateral extent of less than 250 μm, are critical for formation of the reconstituted notochord. Fate mapping and histological examination of this region identify 4 possible precursor cell populations. Further studies are underway to determine which of the 4 possible precursor cell types forms or induces the reconstituted notochord, and which tissue interactions underlie this change in cell fate. © 1995 Wiley-Liss, Inc.
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    Ventral mesodermal patterning in Xenopus embryos: Expression patterns and activities of BMP-2 and BMP-4 (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 78-89 
    Details
    ISSN: 0192-253X
    Keywords: Xenopus ; mesoderm ; bone morpho-genetic proteins ; TGF-β receptors ; induction ; eryth-ropoiesis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We provide a comparative analysis of the expression patterns and ventral mesoderm-inducing properties of Xenopus BMP-2 and BMP-4. Transcripts for BMP-2 and BMP-4 are maternally stored in eggs, and zygotic expression of these genes is uniform in the ectoderm and mesoderm in late blastulae. During gastrulation, BMP-2 is expressed at a low level throughout the ectoderm and marginal zone, but at early neurula stages a patch of dorso-anterior cells displays enhanced expression. In contrast, BMP-4 transcripts are restricted to the ventrolateral marginal zone during gastrulation, and in late gastrula and early neurula BMP-4 is expressed in the epidermis but not the neural plate. At post-neurula stages, BMP-2 and BMP-4 transcripts are associated with a variety of mesodermal structures, including the pharyngeal pouches, heart, blood island, and blastopore. At tailbud stages, BMP-2 and BMP-4 are expressed in neural tissues including the neural tube and brain. In mesoderm induction assays, BMP-2 and BMP-4 induce Xhox3, an early ventral-posterior mesoderm marker, and larval βT1 globin, a marker for red blood cells. Induction of red blood cells in response to BMP-4 was demonstrated by staining with a hemoglobin-specific reagent. Little is known about factors that induce hematopoietic lineages in vertebrates, and these results provide evidence linking BMP activity and blood differentiation. Globin induction by BMP-2 and BMP-4 is blocked by co-expression of a dominant-negative activin receptor, suggesting that either endogenous activin signals are required for BMP-mediated induction, or that the trancated activin receptor interferes with signaling by BMP receptors. In assays on marginal zone explants, we demonstrate that BMP-4 respecifies dorsal mesoderm to form ventral mesoderm, consistent with its ability to induce blood and to ventralize embryos. BMP-2, however, does not display such activity. The findings extend and support evidence that BMP-2 and BMP-4 function in ventral mesoderm induction and patterning in Xenopus. Our data furthermore high light the multiple functions these factors fulfill during early vertebrate embryogenesis. © 1995 Wiley-Liss, Inc.
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    Widespread expression of the eve1 gene in zebrafish embryos affects the anterior-posterior axis pattern (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 117-128 
    Details
    ISSN: 0192-253X
    Keywords: Homeobox ; even-skipped ; evel ; no tail ntl ; pattern formation ; anterior-posterior axis ; zebrafish embryo ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The zygotic expression of the evel gene is restricted to the ventral and laletul cells of the marginal zone. At later stages, the mRNAs are localized in the most posterior part of the extending tail tip. An evel clone (pcZf14), containing a poly-A tail, has been isolated. In order to address evel gene function, pcZf14 transcript injections into zebrafish embryos have been performed. The injection into uncleaved eggs of a synthetic evel mRNA (12 pg), which encodes a protein of 28 kd, produces embryos with anterior-posterior (A-P) axis defects and the formation of additional axial structures. The first category of 24 h phenotypes (87%) mainly displays a gradual decrease in anterior structures. This is comparable to previous phenotypes observed following Xhox3 messenger injection either in Xenopus or in zebrafish that have been classified according to the index of axis deficiency (zf-IAD). These phenotypes result in anomalies of the development of the neural keel, from microphthalmia to acephaly. The second category (13%) corresponds to the phenotypes described above together with truncal or caudal supernumerary structures. Additional truncal structures are the most prominent of these duplicated phenotypes, displaying a “zipper” shape of axial structures including neural keels and noto-chords. Caudal duplication presents no evident axis supernumerary structures. The observation of these phenotypes suggests an important role for the evel gene in mesodermal cell specification and in the development of the posterior region, and more particularly of the most posterior tail tip where endogenous eve1 messengers are found. © 1995 Wiley-Liss, Inc.
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    Epigenetic programming of differential gene expression in development and evolution (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 188-197 
    Details
    ISSN: 0192-253X
    Keywords: Mouse development ; X chromosome ; epigenetic ; methylation ; imprinting ; evolution ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This review covers data on changing patterns of DNA methylation and the regulation of gene expression in mouse embryonic development. Global demethylation occurs from the eight-cell stage to the blastocyst stage in pre-implantation embryos, and global de novo methylation begins at implantation. We have used X-chromosome inactivation in female embryos as a model system to study specific CpG sites in the X-linked Pgk-1 and Gópd housekeeping genes and in the imprinted regulatory Xist gene to elucidate the role of methylation in the initiation and maintenance of differential gene activity. Methyl-ation of the X-linked housekeeping genes occurs very close in time to their inactivation, thus raising the question as to whether methylation could be causal to inactivation, as well as being involved in its maintenance. A methylation difference between sperm and eggs in the promoter region of the Xist gene, located at the X-chromosome inactivation centre, is correlated with imprinted preferential inactivation of the paternal X chromosome in extra-embryonic tissues. Based on our data, a picture of the inheritance of methylation imprints and speculation on the significance of the Xist imprint in development is presented. On a more general level, an hypothesis of evolution by “adaptive epige-netic/genetic inheritance” is considered. This proposes modification of germ line DNA in response to a change in environment and mutation at the site of modification (e.g., of methylated cytosine to thymine). Epigenetic inheritance could function to shift patterns of gene expression to buffer the evolving system against changes in environment. If the altered patterns of gene activity and inactivity persist, the modifications may become “fixed” as mutations; alternatively, previously silenced gene networks might be recruited into function, thus appearing as if they are “acquired characteristics.” An extension of this hypothesis is “foreign gene acquisition and sorting” (selection or silencing of gene function according to use). “Kidnapping” and sorting of foreign genes in this way could explain the observation that increased complexity in evolution is associated with more “junk” DNA. Adaptive epigenetic/genetic inheritance challenges the “central dogma” that information is unidirectional from the DNA to protein and the idea that Darwinian random mutation and selection are the sole mechanisms of evolution. © 1995 Wiley-Liss, Inc.
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    Chromatin structure and imprinting: Developmental control of DNase-I sensitivity in the mouse insulin-like growth factor 2 gene (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 240-252 
    Details
    ISSN: 0192-253X
    Keywords: Parental imprinting ; insulin-like growth factor 2 ; mouse development ; chromatin structure ; DNase-1 ; DNA methylation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The insulin-like growth factor 2 (Igf2) gene on distal mouse chromosome 7 is expressed predominantly from the paternal allele. In previous studies we identified two regions of paternal allele-specific methylation; one at ˜ 3 kb upstream of promoter 1, and a second in the 3′, coding portion of the gene. The 3′ region is methylated in an expressing tissue (fetal liver), whereas in a non-expressing tissue (fetal brain), it is not methylated. By contrast, in the 5′ region, the paternal allele is highly methylated in all tissues. Here, we have studied another characteristic of chromatin, namely, sensitivity to DNase-1 and have focused our developmental analysis on the two differentially methylated regions of Igf2. In the upstream region, four clustered DNase-I hypersensitive sites (HSS) were detected in embryonic stem (ES) cells and in midgestation embryos, but not in neonatal liver or brain. In promoter 1 (P1), at β 0.3 kb upstream of exon 1, we detected a tissue-specific HSS that was present in neonatal liver, in which P1 is active, but was absent in ES cells, the embryo, and in neonatal brain. No DNase-I HSS were detected in the 3′ differentially methylated region of Igf2. In all these regions, we did not detect differences in DNase-I sensitivity between the parental chromosomes. These results establish major developmental and tissue-specific control of chromatin in the Igf2 locus. The presence of the HSS upstream of Igf2 precedes transcriptional activation of the Igf2 gene and may be indicative of a promoter for another transcript that is transcribed in the opposite direction. The HSS in P1 is largely liver-specific; this promoter therefore is differently regulated than the more general fetal promoters P2 and P3. Whereas methylation can be allele-specific, presumably reflecting the gene imprint, the nuclease sensitivity, as detected by our assay, is not. These results, taken together with previous observations, reveal developmental and tissue-specific complexity in the expression of the parental imprint at the level of chromatin and transcription. We propose that epigenetic features of tissue-specific control and of the control of allelic expression are intricately linked. © 1995 Wiley-Liss, Inc.
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    Masthead (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995) 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020170401
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    Paraquat resistance and starvation conditions in the selection for longevity extremes in drosophila melanogaster populations previously selected for long and short developmental period (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 352-361 
    Details
    ISSN: 0192-253X
    Keywords: Aging ; developmental time ; starvation ; paraquat resistance ; sex influence ; longevity ; Drosophila melanogaster ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This paper analyzes the interaction between resistance to free radicals, development under starvation conditions, sex, and its consequences to the lifespan of Drosophila mela-nogaster populations selected for developmental time and longevity. Our data suggest that the interaction between these physiological and environmental parameters is modulated largely by the pre-imaginal developmental time, since the response to selection for longevity extremes depends strongly on the previous selection for developmental time extremes.
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    Genomic mismatch scanning: Current progress and potential applications (1995)
    Weinheim : Wiley-Blackwell
    Electrophoresis 16 (1995), S. 279-285 
    Details
    ISSN: 0173-0835
    Keywords: Genetics ; Linkage(genetics) ; Polymorphism ; Chromosome mapping ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Genomic mismatch scanning (GMS) is a new method of genetic mapping which attempts to purify and map the regions of identity between two complex genomes in a single test. Identical DNA fragments from two genomic sources are enriched in two steps: (i) after reannealing of the two genomes, heterohybrids are purified by using a combination of a restriction methylase and methylation-sensitive endonucleases, (ii) heterohybrids that contain mismatches are nicked in vitro by the E. coli MutHLS mismatch repair system and are eliminated subsequently from the pool, leaving only mismatch-free heterohybrids. The genomic origin of this selected pool of DNA fragments is then mapped in a single hybridization step onto metaphase chromosomes or ordered DNA arrays. The principal advantages of GMS are (i) it approaches the theoretical limit of mapping power and resolution offered by an arbitrarily dense set of completely informative polymorphic markers and (ii) it results in a great increase in the effective number of informative markers without a corresponding increase in the number of individual tests. Thus, it should provide an efficient method for affected-relative-pair linkage mapping and for linkage disequilibrium mapping. In addition, a variation of GMS may allow rapid genomic scanning for regions of homozygosity-by-descent or somatic loss-of-heterozygosity. The feasibility of GMS has been validated in the 15 mb genome of Saccharomyces cerevisiae. This article discusses the principles of GMS, the application to more complex genomes, and the possible uses of GMS.
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    URL: http://dx.doi.org/10.1002/elps.1150160144
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    Is the sphere organelle/coiled body a universal nuclear component? (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 25-35 
    Details
    ISSN: 0192-253X
    Keywords: GV ; snRNPs ; RNA processing ; sphere organelle ; coiled body ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We present evidence for the essential homology of four nuclear organelles that have previously been described under four different names: coiled bodies in mammalian somatic nuclei, prenucleolar bodies in nuclei assembled in vitro in Xenopus egg extract, sphere organelles in amphibian germinal vesicles (GVs), and Binnenkörper in insect GVs. Each of these organelles contains coilin or a coilin-related protein plus a variety of small nuclear ribonucleoproteins. We suggest that the sphere organelle/coiled body is a “universal” nuclear component in the sense that it is involved in common nuclear processes and hence will be found in one form or another in most eukaryotic cells. We postulate that it functions in the assembly and sorting of snRNP complexes for three RNA processing pathways: pre-mRNA splicing, rRNA processing, and histone pre-mRNA 3′ end formation. Specifically, the sphere organelle/coiled body may be the initial site for assembly of processing complexes, which are then sorted to other places in the nucleus, where the actual RNA processing takes place. © 1995 Wiley-Liss, Inc.
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    Masthead (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995) 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1002/dvg.1020160101
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    Fusome asymmetry and oocyte determination in Drosophila (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 6-12 
    Details
    ISSN: 0192-253X
    Keywords: Fusome ; germline cyst ; oocyte determination ; asymmetric mitosis ; Drosophila ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Germline cysts containing 16 interconnected cells (cystocytes) are produced at an early stage of Drosophila oogenesis by progenitor cells known as cystoblasts that undergo four synchronous rounds of incomplete division. During cyst formation, a region of specialized, spectrin-rich cytoplasm called the fusome traverses the intercellular Connections (ring canals), linking individual cystocytes. Subsequently, 15 cystocytes begin to transport specific RNAs and other components into the remaining cell, the future oocyte. We used fusome-specific antibodies to characterize the early stages of cyst formation. During the first cystoblast division, a spherical mass of fusome material (the “spectrosome”) was associated with only one pole of the mitotic spindle, revealing that this division is asymmetric. During the subsequent three divisions, the growing fusome always associated with the pole of each mitotic spindle that remained in the mother cell, and only extended through the newly formed ring canals after each division was completed. These observations suggest that fusomes help establish a system of directional transport between cystocytes that underlies oocyte determination. © 1995 Wiley-Liss, Inc.
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    Genomic organization of a mouse glyceraldehyde 3-phosphate dehydrogenase gene (Gapd-s) expressed in post-meiotic spermatogehic cells (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 179-189 
    Details
    ISSN: 0192-253X
    Keywords: Spermatogenesis ; glycolysis ; gene expression ; enzyme ; glyceraldehyde 3-phosphate dehydrogenase ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The Gapd-s gene encodes an isoform of the glyceraldehyde 3-phosphate dehy-drogenase enzyme expressed only in post-meiotic spermatogenic cells. Two clones containing the Gapd-s gene were isolated from a mouse genomic library. Sequencing and restriction enzyme analysis demonstrated that this single-copy gene contains 11 exons and spans 9596 base pairs. The locations of Gapd-s exons and introns are conserved when compared to the corresponding portions of the chicken and human somatic Gapd genes. The promoter region contains no TATA box, although there is a potential SP1 recognition site within exon 1. Like other TATA-less genes, primer extension analysis reveals some heterogeneity in the site of transcription initiation with Gapd-s transcripts initiating from three discrete sites. Northern analysis demonstrated that a 1.5-kb Gapd-s mRNA is expressed in the testis in at least three mammalian orders, indicating that the Gapd-s gene appeared early in mammalian evolution. Using GAPD-deficient bacteria, mouse GAPD-S was shown to be capable of functioning as a glycolytic enzyme. Since GAPD has been proposed to be a key enzyme regulating glycolysis in spermatogenic cells, GAPD-S may represent a potential target for toxicological or contraceptive agents affecting fertility by interfering with glycolysis. © 1995 Wiley-Liss, Inc.
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    The making of a spermatozoon: A molecular perspective (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 95-103 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020160202
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    Transcriptional regulation of Sertoli cell differentiation (transferrin promoter activation) during testicular development (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 114-118 
    Details
    ISSN: 0192-253X
    Keywords: Sertoli cell ; transferrin promoter ; mesenchymal-epithelial ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Previously testicular peritubular cells have been shown to produce a paracrine factor PModS that promotes Sertoli cell differentiation. This mesenchymal-epithelial cell interaction appears to regulate a number of Sertoli cell differentiated functions including transferrin gene expression. The current study was designed to identify PModS-activated response elements in the transferrin promoter and correlate this with Sertoli cell differentiation that occurs during testis development. The 3-kb transferrin promoter was digested down to approximately 200-bp fragments. Nuclear extracts from Sertoli cells stimulated with PModS were used in gel mobility shift assays. Two promoter regions located at -2.4 kb and -1.9 kb were designated SE1 and SE2. PModS promoted the presence of factors in Sertoli cell nuclear extracts that bind SE1 and SE2. Displacement studies demonstrated that SE1 and SE2 are distinct. A transferrin promoter-reporter construct containing these apparent response elements was activated by PModS, while a minimal transferrin promoter of 600bp excluding SE1 and SE2 was only partially stimulated by PModS. Therefore, PModS appears to in part activate the transferrin promoter through SE1 and/or SE2. Gel shift assays with Sertoli cell nuclear extracts and 20-day-old testis extracts were the same. Interestingly, the nuclear extract from a new-born testis also had a gel shift. Therefore, some of the nuclear factors stimulated by PModS in Sertoli cells and present in mid-pubertal testis were also present at birth upon completion of embryonic development. Previously transferrin expression has been shown to increase significantly at the onset of puberty. Observations indicate that PModS appears to in part promote transferrin expression through two newly identified response elements designated SE1 and SE2 and that the nuclear factors that bind these elements are present after embryonic development and mid-pubertally. © 1995 Wiley-Liss, Inc.
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    Regulation of β-tubulin function and expression in Drosophila spermatogenesis (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 148-170 
    Details
    ISSN: 0192-253X
    Keywords: Tubulin ; microtubules ; testis ; spermatogenesis ; Drosophila ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In this study we examined two aspects of β-tubulin function in Drosophila spermatogenesis: 1) β-tubulin structural requirements for assembly of different categories of microtubules and 2) regulatory requirements for production of the correct tubulin protein level. In normal Drosophila spermatogenesis, the testis-specific β2-tubulin isoform supports multiple microtubule functions. Our previous work showed that another Drosophila isoform, β3, cannot support spermatogenesis, whereas a carboxyl-truncated form of β2, β2ΔC, can at least to some extent provide all of β2′s normal functions, save one: β2ΔC cannot support organization of axonemal microtubules into the supramolecular architecture of the axoneme. Here, to test whether β2 carboxyl sequences can rescue the functional failure of the β3 isoform in spermatogenesis, we constructed a gene encoding a chimeric protein, β3β2C, in which β3 sequences in the carboxyl region are replaced with those of β2. Unlike either β3 or β2ΔC, β3β2C can provide partial function for both assembly of axonemal microtubules and their organization into the supramolecular architecture of the axoneme. In particular, the β2 carboxyl sequences mediate morphogenesis of the axoneme doublet tubule complex, including accessory microtubule assembly and attachment of spokes and linkers. However, our data also reveal aspects of β2-specific function that require structural features other than the primary sequence of the isotype-defining variable regions, the C terminus and the internal variable region. Tests of fecundity in males that co-express Δ2 and the chimeric Δ3Δ2C protein showed that in Drosophila there are differential requirements for sperm motility in the male and in the female reproductive tract. Since some aspects of microtubule function in spermatogenesis are sensitive to the tubulin pool size, we examined the mechanisms for control of tubulin protein levels in the male germ cells. We found that both Δ2-tubulin mRNA accumulation and protein synthesis are dependent on gene dose, and that the level of expression is regulated by 3′ noncoding sequences in the Δ2 gene. Our data show that the regulatory mechanisms that control tubulin pool levels in the Drosophila male germ line differ from those observed in cultured animal somatic cells. Finally, expression of transgenic constructs is consistent with early cessation of × chromosome expression in Drosophila spermatogenesis. © 1995 Wiley-Liss, Inc.
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    Serum response element associated transcription factors in mouse embryos: Serum response factor, YY1, and PEA3 factor (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 229-240 
    Details
    ISSN: 0192-253X
    Keywords: Muscle regulatory element ; O-glycosylation ; PEA3 ; Serum response element ; Serum response factor ; YY1 ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Many mammalian transcription factors, including human and mouse serum response factors (SRFs), are post-translationally modified with O-linked N-acetylglucosamine monosaccharides on multiple serine and/or threonine residues. Nuclear extracts were prepared from 9.5 to 19 days postcoitum mouse embryos and subsequently were fractionated by wheat germ agglutinin (WGA)-agarose affinity chromatography. SRF binds WGA-agarose and apparently is O-glycosylated. On the other hand, the low molecular weight serum response element (SRE)-binding proteins, including the previously named band I and band II factors, did not bind WGA-agarose. Furthermore, we showed that the fastest migrating complex contains the Yin-Yang 1 (YY1) factor. YY1 binds to the c-fos SRE and skeletal β-actin muscle regulatory element (MRE), but not the cardiac β-actin MRE. Nuclear extracts from NIH/3T3 fibroblasts contain similar, if not identical, SRE-binding complexes. Besides these SRE-binding factors, mouse PEA3-binding factor, presumably an ETS domain-containing protein, was found to bind SRF protein. This physical interaction, between SRF and ETS domain proteins, was shown to involve the DNA-binding domain-containing region of SRF and not the carboxyl-terminal transactivation domain. © 1995 Wiley-Liss, Inc.
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    Masthead (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995) 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020160401
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    Genes and embryo morphogenesis in angiosperms (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 291-297 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020160402
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    Late embryo-defective mutants of Arabidopsis (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 311-320 
    Details
    ISSN: 0192-253X
    Keywords: Arabidopsis thaliana ; embryogenesis ; embryo-defective mutants ; morphogenesis ; pattern formation ; vegetative development ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The embryo-defective (emb) mutants of Arabidopsis constitute a large and diverse group of mutants disrupted in a broad range of embryonic processes, including morphogonesis, cell differentiation, and maturation programs. This report describes a subset of these mutants, the late embryo defectives, which develop beyond the globular stage of embryogenesis but fail to complete normal morphogenesis. A representative sample of 12 late mutants was chosen for this study, patterns of morphogenesis were characterized, the germination potential of mutant seeds was investigated, and additional mutant alleles within the collection were identified. Morphological defects in mutant embryos became apparent during the heart stage of development, when embryos normally begin the rapid cell division and expansion required for the completion of morphogenesis. Despite their morphological abnormalities, mutant embryos often germinated from dry seed, demonstrating that genetic programs required for the establishment of desiccation tolerance remained intact. Mutant seedlings displayed a wide range of developmental abnormalities, including altered morphology, lack of pigmentation, dwarfism, and disorganized vegetative growth. One late mutant was found to be allelic to an early embryo defective that arrests at the globular stage. These results suggest that a number of late EMB genes encode basic cellular and metabolic functions needed for cell division, enlargement, and embryonic growth. The rapid growth and metabolic changes that occur at the heart stage may present a barrier to normal development in the late mutants, resulting in altered embryo morphology and other developmental defects. It is proposed that many Arabidopsis mutants with abnormal embryo and seedling morphology are not defective in the regulation of pattern formation or morphogenesis, but rather in fundamental physiological and cellular processes required for the completion of normal growth and development. © 1995 Wiley-Liss, Inc.
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    Transcription of the Zea mays homeobox (ZmHox) genes is activated early in embryogenesis and restricted to meristems of the maize plant (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 349-357 
    Details
    ISSN: 0192-253X
    Keywords: Zea mays homeobox genes ; in situ hybridization ; embryogenesis ; meristems ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Four Zea mays homeobox (ZmHox) genes have been analyzed in their spatial expression pattern during development of the maize plant. The ZmHox1a or b and ZmHox2a or b gene pairs encode putative plant transcriptin factors; the mRNA transcripts belong to the rare class of mRNA molecules. Expression of the ZmHox1 and 2 genes is activated very early in embryonic development and restricted to the embryo proper in the proembryo stage. After establishment of the root/shoot axis, transcripts are prevalent in the embryonic root and shoot apical meristems but later are also found in provascular tissues and young leaf primordia. In the vegetative plant body the transcription of the ZmHox genes marks several types of meristems of the shoot and root system, the descending proliferating regions and provascular strands. Expression persists in the developing reproductive organs, but results obtained in the male flower indicate that transcription of ZmHox genes here may become confined to specific cell types. The data obtained during this study show that these four ZmHox genes are expressed very specifically in cells where developmental decisions contribute to the ontogeny of the maize plant. The overall expression pattern suggests that the ZmHox class of maize homeobox genes will be involved in transcriptional control during maize development from the embryonic to the reproductive phase. © 1995 Wiley-Liss, Inc.
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    Masthead (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995) 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020170101
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    Allocation of epiblast cells to germ layer derivatives during mouse gastrulation as studied with a retroviral vector (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 29-37 
    Details
    ISSN: 0192-253X
    Keywords: Gastrulation ; mouse embryo ; retro-viral vector ; β-galactosidase ; embryo culture ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The embryonic ectoderm, or epiblast, is the source of the three primary germ layers that form during gastrulation in the mouse embryo. Previous studies have investigated the fate of epiblast cells in early gastrulation stages using clonal analysis of cell lineage and in late gastrulation stages using transplantation of labeled grafts. In this study, we studied the fate of late gastrulation stage epiblast using a clonal analysis based on a retroviral vector encoding the Escherichia coli lacZ gene. We found that by reducing the volume of viral suspension injected into each embryo, it was possible to achieve single infectious events. Our analysis of 20 embryos singly infected at the late streak stage and 21 at the head fold stage revealed clonal descendants in only a single germ layer in each embryo. These results indicate that allocation of epiblast progenitors to a single germ layer fate has occurred by late gastrulation in mouse embryos. © 1995 Wiley-Liss, Inc.
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    Expression of HGF/SF, HGFI/MSP, and c-met suggests new functions during early chick development (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 90-101 
    Details
    ISSN: 0192-253X
    Keywords: Hepatocyte growth factor ; scatter factor ; HGF/SF ; hepatocyte growth factor-like ; macrophage stimulating protein ; HGFI/MSP ; c-met ; chick embryo ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We report the cloning of full-length cDNAs for a plasminogen-related growth factor, hepatocyte growth factor/scatter factor (HGF/SF), its tyrosine kinase receptor, c-met, and a close member of the same family, hepatocyte growth factor-like/macrophage stimulating protein (HGFI/MSP), from the chick. We have used these cDNAs to provide the first report of the expression of this family of growth factors and the c-met receptor at early stages of vertebrate development. RNAase protection and wholemount in situ hyb ridization were used on chick embryos between formation of the primitive streak and early organogenesis. We find patterns of expression for HGF/SF and its receptor c-met consistent with their known roles in ep ithelial-mesenchymal transformation and angiogenesis. In addition, these genes and HGFI/MSP are expressed in discrete locations within developing somites, suggesting a role in paraxial mesodermal development. Very strong and early expression of HGF/SF in the elevating limb buds suggests its involvement in limb outgrowth. HGFI/MSP is expressed in the notochord and then in the prospective floor plate region and could play a role in development of the neural tube. Interestingly, c-met is often more closely as sociated with HGFI/MSP than with its known ligand, HGF/SF, raising the possibility that c-met expression may be induced by HGFI/MSP. © 1995 Wiley-Liss, Inc.
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    Cell fate decisions in the early embryo of the nematode Caenorhabditis elegans (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 155-166 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/dvg.1020170207
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    Characterization of a gene trap insertion into a novel gene, cordon-bleu, expressed in axial structures of the gastrulating mouse embryo (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 141-154 
    Details
    ISSN: 0192-253X
    Keywords: Gene trap ; lacZ reporter ; gastrulation ; cordon-bleu ; node ; mouse axis formation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have used a gene trap (GT) vector and embryonic stem (ES) cell chimeras to screen for insertions of the lacZ reporter gene into transcription units that are spatially and temporally regulated during early mouse embryogenesis. GT vectors which can act as both a reporter and a mutagen have been previously used to isolate new genes that are essential for mouse development. In this paper we describe a GT insertion which displays a very restricted pattern of expression in the gastrulating embryo. β-Galactosidase activity was first detected at 7.5 days post-coitum (E7.5) in the node region of the embryo and extended to the midline structures at E8.0. At E9.5 expression was restricted to the floor plate, the notochord, the roof of the gut, and the liver anlage. Expression appeared in the somites at E10.0 and later became more widespread. We used rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR) to clone a partial 360 base pair (bp) cDNA representing an endogenous sequence and containing an open reading frame (ORF) fused in frame to the lacZ reporter gene. The sequence showed no homology to any known protein or protein domain. An overlapping 1,200 bp fragment from a wild-type cDNA library was cloned and it detected the same pattern of expression as the reporter gene in E7.5, E8.5, and E9.5 wild-type embryos. It hybridized to a 5.4 kb lacZ fusion transcript and to an endogenous transcript of 6.5 kb. The gene was mapped to chromosome 11 and was named cordon-bleu (cobl). No phenotype was detected in mice homozygous for the insertion. However, the insertion may not cause a complete disruption of the gene function. The pattern of expression of cobl is very similar to that of hepatic nuclear factor 3β (HNF3β) and sonic hedgehog (Shh), both of which are involved in axial patterning. Therefore, the product of the cobl gene may also prove to be an important component of the genetic pathway regulating vertebrate axis formation. © 1995 Wiley-Liss, Inc.
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    Involvement of differential gene expression and mRNA stability in the developmental regulation of the hsp 30 gene family in heat-shocked Xenopus laevis embryos (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 176-184 
    Details
    ISSN: 0192-253X
    Keywords: Xenopus laevis ; heat-shock protein ; mRNA stability ; polymerase chain reaction ; differential gene expression ; developmental gene expression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Four complete hsp 30 genes have been isolated from Xenopus laevis: hsp 30A, hsp 30B (a pseudogene), hsp 30C, and hsp 30D. The hsp 30A and hsp 30C genes are first heat inducible at the early tailbud stage, as determined by RNase protection and RT-PCR assays. In this study, we determined by RT-PCR that the hsp 30D gene was first heat inducible (33oC for 1 h) at the mid-tailbud stage, approximately 1 day later in development than hsp 30A and hsp 30C. Furthermore, using Northern blot analysis, we detected the presence of very low levels of hsp 30 mRNA at the heat-shocked late blastula stage. The relative levels of these pre-tailbud (PTB) hsp 30 mRNAs increased at the gastrula and neurula stage followed by a dramatic enhancement in heat shocked tail-bud and tadpole stage embryos (50- to 100- fold relative to late blastula). Interestingly, treatment of blastula or gastrula embryos at high temperatures (37oC for 1 h) or with the protein synthesis inhibitor, cycloheximide, followed by heat shock, led to enhanced accumulation of the pre-tailbud (PTB) hsp 30 mRNAs. hsp 70, hsp 87, and actin messages were not stabilized at high temperatures or by cycloheximide treatment. Finally, hsp 30D mRNA was not detected by RT-PCR analysis of cycloheximidetreated, heat-shocked blastula stage embryos, confirming that it is not a member of the PTB hsp 30 mRNAs. This study indicates that differential gene expression and mRNA stability are involved in the regulation of hsp 30 gene expression during early Xenopus laevis development. © 1995 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/dvg.1020170209
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    Expression of X-linked genes in androgenetic, gynogenetic, and normal mouse preimplantation embryos (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 212-222 
    Details
    ISSN: 0192-253X
    Keywords: Genome imprinting ; X chromosome ; mouse embryo ; nuclear transplantation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A quantitative RT-PCR approach has been used to examine the expression of a number of X-linked genes during preimplan-tation development of normal mouse embryos and in androgenetic and gynogenetic mouse embryos. The data reveal moderately reduced expression of the Prps1, Hprt, and Pdha1 mRNAs in androge-netic eight-cell and morula stage embryos, but not in androgenetic blastocysts. Pgk1 mRNA abundance was severely reduced in androgenones at the eight-cell and morula stages and remained reduced, but to a lesser degree, in androgenetic blastocysts. These data indicate that paternally inherited X chromosomes are at least partially repressed in androgenones, as they are in normal XX embryos, and that the degree of this repression is chromosome position-dependent or gene-dependent. Gynogenetic embryos expressed elevated amounts of some mRNAs at the morula and blas-tocyst stages, indicative of a delay in dosage compensation that may be chromosome position-dependent. The Xist RNA was expressed at a greater abundance in androgenones than in gynogenones at the eight-cell and morula stages, consistent with previous studies. Xist expression was observed in both and rogenones and gynogenones at the blas-tocyst stage. We conclude that the developmental arrest in early androgenones may be, in part, due to reduced expression of essential X-linked genes, particularly those near the X inactivation center, where as the developmental defects of gyno-genones and parthenogenones, by contrast, may be partially due to overexpression of X-linked genes in extraembryonic tissues, possibly those far-thest away from the X inactivation center. © 1995 Wiley-Liss, Inc.
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    URL: http://dx.doi.org/10.1002/dvg.1020170306
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    Spatial expression of the hsr-omega (93D) gene in different tissues of drosophila melanogaster and identification of promoter elements controlling its developmental expression (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 303-311 
    Details
    ISSN: 0192-253X
    Keywords: Heat shock ; non-coding RNA ; germline transformation ; prothoracic gland ; housekeeping gene ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Developmental expression of the heat shock inducible non-protein coding hsromega gene in several larval and adult tissues of Drosophila melanogaster was examined by in situ hybridization to transcripts in intact organs and by X-gal staining in the germline transformants carrying the lacZ reporter gene under the control of hsromega promoter. This gene is expressed in a specific spatial pattern in all the larval and adult tissue types examined; however, its transcripts were specifically absent in certain gonadal cell types like the male as well as female gonial cells and in follicle cells and oocytes in ovary. All polytenised tissues like the prothoracic and salivary glands, certain regions of larval gut and the Malpighian tubules showed a greater abundance of hsr-omega transcripts with a strong hybridization in nuclei. Our results with promoter deletion variant germline transformants suggest that a region between -346bp to -844bp upstream contains major regulatory element/s for developmental expression of this gene in most of the larval and adult tissues examined; however, this region is not sufficient for its normal expression in male and female reproductive systems. An analysis of the base sequence of the hsr-omega promoter (upto -844bp) reveals putative ecdysone receptor element half-sites and two GAGA factor binding sites which may be involved in its developmental expression and its ready inducibility. The widespread expression in most tissue types and the known lethality associated with its homozygous deletion, suggest that the variety of non-protein coding transcripts of the hsromega gene have vital “house-keeping” functions.
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    URL: http://dx.doi.org/10.1002/dvg.1020170403
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    Developmental alteration of the chromatin state at promoter/replication origin region of the aldolase b locus precedes transcriptional activation in the liver (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 312-318 
    Details
    ISSN: 0192-253X
    Keywords: Aldolase B gene ; chromatin structure ; DNase I-hypersensitive site ; CpG methylation ; transcription ; replication origin ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Liver-specific expression of the rat aldolase B (AldB) gene is conferred by proximal promoter region (-200 bp to + 1 bp), which is centered on an origin region of DNA replication. Transcriptional activation of the gene in the liver occurs during the late one-third of fetal stage. To know the mechanism involved in such activation, we studied developmental changes in chromatin structure and in the extent of CpG methylation in the promoter/origin region of the gene. At an early fetal stage, when the AldB gene in the liver is not yet activated, the gene chromatin had two DNase l-hypersensitive sites in the promoter region. One corresponded to that typical of AldB-expressing cells in the adult. The other, located ∼200 bp upstream of the above site, disappeared as the activation of transcription started. A CpG dinucleotide in the promoter/origin region was heavily methylated at an early stage of gestation, but progressively demethylated as the liver develops. This CpG site is located at the center of an important binding site for a transcription factor. These changes occurred early in the fetal stage, prior to the gene activation, and were thus thought to be associated with differentiation of the liver cell or with cessation of cell proliferation.
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    Comparative biochemical and stress analysis of genetically selected drosophila strains with different longevities (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 340-351 
    Details
    ISSN: 0192-253X
    Keywords: Genetics of aging ; extended longevity ; biomarkers ; biochemisty and longevity ; stress resistance and longevity ; paraquat ; antioxidant activity ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have performed a comparative analysis of the effects of age of reproduction on the biochemical (protein, lipid, and glycogen content) and stress resistance (ability to survive starvation, desiccation, and exogenous paraquat) parameters on 10 sister lines of five different Drosophila strains. Four pairs of these sister lines were selected under different regimens for either early or delayed reproduction; the fifth pair was maintained in a nonselected state and served as the baseline strain to which all others were compared. It is generally accepted that the early regimens give rise to short-lived phenotypes, whereas the delayed regimens give rise to long-lived phenotypes. Our results suggest that a mechanism involving lipid and starvation resistance is not operative in our long-lived strains. In addition, a mechanism involving glycogen content and desiccation resistance is only weakly supported. Finally, there is strong support for a mechanism that gives rise to enhanced paraquat resistance and therefore may involve regulatory changes in the pattern of ADS gene expression. In addition, the 15-day early age at reproduction regimen (M type) shows qualitatively similar responses to that of the late age at reproduction regimen (L type). These results suggest that correlations between biochemical traits and longevity must be interpreted with caution. We discuss possible reasons for these results, including the possibility of multiple mechanisms, each leading to a different extended longevity phenotype.
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    Oogenesis: Variations on a theme (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 1-5 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020160103
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    A haploid and a diploid cell cycle coexist in an in vitro immortalized spermatogenic cell line (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 119-127 
    Details
    ISSN: 0192-253X
    Keywords: Germ cell line ; FACS ; mitosis ; meiosis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have recently established a conditionally immortalized germ cell line [GC-2spd(ts)] that, at the permissive temperatures of 37°C and 32°C, is able to undergo meiosis in vitro and form round spermatids [Hofmann et al., (1994): Proc Natl Acad Sci USA 91:5533-5537]. In this report, we provide data that indicate that the GC-2spd(ts) cell line consists of two cell populations undergoing a haploid (n/2n) cell cycle and a diploid (2n/4n) cell cycle, respectively. The cells containing 2n DNA, when sorted by fluorescence-activated cell sorting, are able to reconstitute the full population of n/2n/4n DNA cells, indicating that they are able to commit to the reductive meiotic division and form haploid spermatids or to continue self-replication through a diploid cell cycle. This GC-2spd(ts) cell line provides a valuable tool to study the molecular mechanisms involved in the cellular decision between self-renewal by mitosis and commitment to meiosis. © 1995 Wiley-Liss, Inc.
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    Deficiency analysis of female gametogenesis in maize (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 44-63 
    Details
    ISSN: 0192-253X
    Keywords: Maize ; embryo sac ; deficiency phenotypes ; genetic requirements ; megagameto-genesis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Plants produce female gametes through mitotic division in the multicellular, meioticolly reduced (haploid) megagametophyte phase. In flowering plants, the megagametophyte is the embryo sac; female gametogenesis or megagametogenesis comprises the ontogeny of the embryo sac. As a step toward understanding the role of embryo sac-expressed genes in megagametogenesis, development of normal, haploid embryo sacs in maize was compared with development of embryo sacs deficient for various small, cytologically defined chromosomal regions. This analysis allowed us to screen 18% of the maize genome, including most of chromosome arms 1L and 3L, for phenotypes due specifically to deletion of essential, embryo sac-expressed genes. Confocal laser scanning microscopy of whole developing embryo sacs confirmed that normal megagameto-genesis in maize is of the highly stereotyped, bipolar Polygonum type common to most flowering plants examined to date. Deficiency embryo sac phenotypes were grouped into three classes, suggesting each deficient region contained one or more of at least three basic types of haploid-expressed gene functions. In the first group, three chromosome regions contained genes required for progression beyond early, free-nuclear stages of embryo sac development. Maintaining synchrony between events at the two poles of the embryo sac required genes located within two deficiencies. Finally, three chromosome regions harbored loci required for generation of normal cellular patterns typical of megagametogenesis. This analysis demonstrates that the embryo sac first requires postmeiotic gene expression at least as early as the first postmeiotic mitosis. Furthermore, our data show that a variety of distinct, genetically separable programs require embryo sac-expressed gene products during megagametogenesis, and suggest the nature of some of those developmental mechanisms. © 1995 Wiley-Liss, Inc.
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    Developmental and genetic mosaic analysis of Drosophila m-dy mutants: Tissue foci for behavioral and morphogenetic defects (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 85-93 
    Details
    ISSN: 0192-253X
    Keywords: miniature-dusky ; Andante ; circadian pacemaker ; wing a morphogenesis ; ts mutant ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Mutants of the Drosophila miniature-dusky (m-dy) gene complex display morphogenetic phenotypes (miniature or dusky) caused by a change in the size and/or shape of the epidermal cells comprising the adult wing. In addition to a dusky phenotype, certain Andante-type mutants also exhibit lengthened circadian periods for two different behavioral rhythms. If the latter phenotype results from a direct effect on the circadian pacemaker, the Andante function should be required within the brain. In order to define the tissues that require the morphogenetic and behavioral functions, we have carried out a genetic mosaic analysis. This study demonstrates that normal wing morphogenesis is entirely dependent on the genotype of wing cells. Furthermore, temperature-shift experiments with a temperature-sensitive dy mutant indicate that the morphogenetic function is required during adult development, and after the cessation of wing epidermal cell proliferation. At this time in development, a columnar epithelium in the developing wing becomes flattened into the mature wing blade, and we postulate that the cell-size defect of m-dy mutants results from an alteration of this mor-phogenetic process. In contrast to the wing mor-phogenesis phenotype, the characterization of locomotor activity in mosaic adults revealed a strong correlation between the head genotype and the Andante circadian-period phenotype. This result indicates that neural tissues mediate the rhythm function. Thus, the behavioral and morphogenetic functions require gene expression in distinct tissues. Furthermore, the behavioral results are consistent with a requirement for Andante function within circadian pacemaker neurons. © 1995 Wiley-Liss, Inc.
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    Culture of pachytene spermatocytes for analysis of meiosis (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 128-139 
    Details
    ISSN: 0192-253X
    Keywords: Spermatogenesis ; meiosis ; synapsis ; synaptonemal complex ; G2-M transition ; okadaic acid ; actinomycin D ; camptothecin ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: An impediment to the investigation of mammalian spermatogenic meiosis has been the lack of an appropriate system for experimental manipulation of meiotic prophase cells. We report here the use of a simple system for the short-term culture of pachytene spermatocytes. We have assayed parameters of cell function pertinent to meiotic prophase, namely chromosome pairing and synapsis. During the culture period of 24-48 hr, cells maintained typical pachytene morphology, chromatin condensation patterns, and chromosome pairing, as assessed by light and electron microscopy. Uridine incorporation, monitored by autoradiography, reflected the chromosomal distribution found in vivo in that the autosomal chromosomes were transcriptionally active, while the sex chromosomes were not. Thus features of chromosome pairing and sex chromatin inactivation are maintained in these cultures. We have conducted experiments to demonstrate that cultured pachytene spermatocytes can be useful for the analysis of agents, some of which may be suspected mutagens, that might affect chromosome structure and function during meiosis. Treatment of cells with actinomycin D revealed a differential effect on chromatin condensation in the autosomes versus the sex chromosomes. Carnptothecin, a topoisomerase inhibitor, induced desynapsis of paired chromosomes. Okadaic acid, a phosphatase inhibitor, induced premature metaphase-I condensation of pachytene chromosomes. This last experiment suggests that these cultured cells may be useful for analysis of meiotic cell cycle controls. Taken together, these results demonstrate a culture system that can be useful for analysis of meiotic events as well as in screening for potential mutagenic agents that might affect meiotic chromosome structure and function. © 1995 Wiley-Liss, Inc.
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    Polarization of mitochondria in the unfertilized mouse oocyte (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 36-43 
    Details
    ISSN: 0192-253X
    Keywords: Polarization ; mitochondria ; oocyte ; meiotic maturation ; development ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Maturation of an immature oocyte into one capable of being fertilized involves tightly choreographed movements of chromosomes and organelles. The localizaton of mitochondria during maturation was studied in live mouse oocytes by confocal laser scanning microscopy (CLSM). Mitochondria were labeled with rhodamine 123 or Mitotracker (Molecular Probes, Eugene, OR) both of which are cell permeant and accumulate in mitochondria; acridine orange was used to mark chromatin. Prior to maturation, oocytes appeared to be radially symmetrical with no evident polarity; fully mature oocytes exhibited obvious polarity marked by the position of the metaphase II spindle in the cortex. CLSM revealed several interesting features of mitochondrial distribution: (1) A cortical clump of mitochondria was seen approximately 30-45to one side of the metaphase II spindle and marked the region of polar body I extrusion. (2) Large foci of mitochondria (7-14μM) were frequently found around the central region of the mature oocyte, while the central region often exhibited markedly fewer mitochondria. (3) Small mitochondrial foci (3μM) in the cortex and near the GV characterized several oocytes which failed to mature. (4) Non-spindle-associated mitochondria were not uniformly distributed in the mature oocyte but were concentrated in the hemisphere containing the metaphase II spindle. (5) The distal margins of this mitochondrial hemisphere were sharply demarcated at the cortex. These findings should help us understand organelle localization during mammalian oocyte maturation, and may give insights into possible causes of infertility and into early events of preimplantation development. © 1995 Wiley-Liss, Inc.
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    Masthead (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995) 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020160201
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    Estradiol regulates N-cadherin mRNA levels in the mouse ovary (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 20-24 
    Details
    ISSN: 0192-253X
    Keywords: Cadherins ; ovary ; granulosa cells ; steroids ; cell adhesion molecules ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: N-cadherin (N-cad) is a calcium-dependent cell adhesion molecule which is present in the granulosa cells of the mouse ovarian follicle. This cell adhesion molecule has been implicated as a key modulator of follicular development. The regulators of N-cad mRNA levels in the ovary have not been identified. We have examined the ability of steroids to influence ovarian N-cad mRNA levels in vivo. Immature mice were injected with either progesterone, testosterone, 17β-estradiol, or 17α-estradiol. Only 17β-estradiol caused a rapid and significant increase in the ovarian N-cad mRNA levels. We speculate that this steroid is a major regulator of N-cad-mediated granulosa cell interactions in vivo. © 1995 Wiley-Liss, Inc.
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    Tumor suppression in Drosophila is causally related to the function of the lethal(2)tumorous imaginal discs gene, a dnaJ homolog (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 64-76 
    Details
    ISSN: 0192-253X
    Keywords: Tumor suppression ; Drosophila ; imaginal discs ; dnaJ-homolog ; chaperone ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The Drosophila melanogaster tumor suppressor gene lethal(2)tumorous imaginal discs (l(2)tid) causes in homozygotes malignant growth of cells of the imaginal discs and the death of the mutant larvae at the time of puparium formation. We describe the molecular cloning of the 1(2)tid+ gene and its temporal expression pattern in the wild-type and mutant alleles. Germ line rescue of the tumor phenotype was achieved with a 7.0 kb Hindlll-fragment derived from the polytene chromosome band 59F5. The l(2)tid+ gene spans approximately 2.5 kb of genomic DNA. The protein coding region, 1,696 bps long, is divided by an intron into two exons. The predicted Tid56 protein contains 518 amino acids and possesses a theoretical molecular weight of 56 kDa. It shows significant homology to all known DnaJ related proteins from bacteria, yeast, and man. The possible function of the Tid56 protein in tumor suppression is delineated. © 1995 Wiley-Liss, Inc.
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    Germ cell-sertoli cell interactions: Regulation by germ cells of the stage-specific expression of CP-2/cathepsin LmRNA by sertoli cells (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 104-113 
    Details
    ISSN: 0192-253X
    Keywords: Spermatogenesis ; CP-2/cathepsin L ; Sertoli cells ; germ cells ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: CP-2/cathepsin LmRNA is expressed primarily by rat Sertoli cells within stage VI-VIII seminiferous tubules. To test whether germ cells regulated this expression, we examined if separating Sertoli cells from specific germ cells affected expression of this transcript in Sertoli cells. First, Sertoli cells were isolated from adult (90-day-old) and immature (25-day-old) rats and levels of this transcript measured immediately or after 1, 3 and 5 days in culture. Results demonstrated that immediately upon isolation, CP-2/cathepsin LmRNA levels were significantly higher in mature cells. However, after 1 day in culture, the levels of this transcript increased in immature cells and remained high in mature cells. We therefore conclude that in vivo, a subset of germ cells inhibit the expression of CP-2/cathepsin LmRNA by immature Sertoli cells. Second, to examine the effect of specific germ cells on CP-2/cathepsin LmRNA expression, we exposed the testes of mature rats to 3 Gy of γ-radiation and analyzed stage-specific expression of this transcript at varying times during maturation depletion and subsequent germ cell restoration. Loss of spermatogonia or spermatocytes was without effect. However, when pachytene spermatocytes through step 14 spermatids were depleted, expression at stages VI-VIII was reduced by half and expression at stages IX-I was increased 14-fold. These changes resulted in the loss of stage-specific expression of CP-2/cathepsin LmRNA by Sertoli cells. Finally, stage VI-VIII tubules, depleted primarily in step 15-19 spermatids, had levels of CP-2/cathepsin LmRNA that were 60% of control. However, stage-specific expression of this transcriot was detected in these tubules. In contrast to whai we noted with CP-2/cathepsin LmRNA, loss and restoration of germ cells had no effect on Sertoli cell levels of SGP-2 mRNA, indicating that testicular irradiation had no Overall effect on Sertoli cell function Taken togetherr these data suggest that the stage-specific expression of the CP-2/ cathepsin L gene results from the sequential stimulation and inhibition of Sertoli cells by germ cells, that pachytene spermatocytes through step 14 spermatids are required for this stage-specific expression and that step 18 and 19 spermatids amplify this expression at stages VI-VIII. © 1995 Wiley-Liss, Inc.
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    Distinct patterns of expression of the D-type cycling during testicular development in the mouse (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 171-178 
    Details
    ISSN: 0192-253X
    Keywords: Cell cycle ; cyclin ; meiosis ; spermato-genesis ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The three D-type cyclins have been shown to be differentially expressed in a number of isolated cell types and cell lines, suggesting distinct roles in cell cycle regulation in particular cell lineages. The testis provides unique opportunities to study genes involved in cell cycle regulation, since it contains cells in both mitosis and meiosis as well as differentiated cells with little proliferation activity. Major transcripts of 4.2 kb, 6.8 kb, and 2.3 kb were detected in the adult mouse testis by Northern hybridization analyses for cyclin D1, cyclin D2, and cyclin D3, respectively. Additional transcripts of 1.8 and 2.7 kb were detected by Northern hybridization for cycin D3 in the testis, but not in other tissues, and these transcripts were limited to germ cells. Northern and in situ hybridization analyses of normal and germ cell-deficient testes showed the surprising result that cyclin D1 was expressed in a pattern consistent with expression in the non-dividing Sertoli cells. Cyclin D2 levels appeared slightly enriched in germ cell-deficient testes as compared to intact testis, but in situ hybridization analysis did not reveal any distinct cellular localization. Also surprising was the observation that cyclin D3 expression was highest in the non-dividing, haploid, round spermatids. The possible roles of these cyclins in the events of spermatogenesis are discussed. © 1995 Wiley-Liss, Inc.
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    Masthead (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995) 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1002/dvg.1020170201
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    The CpG-rich promoter of human LDH-C is differentially methylated in expressing and nonexpressing tissues (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 210-217 
    Details
    ISSN: 0192-253X
    Keywords: CpG island ; lactate dehydrogenase C ; testis ; promoter ; methylation ; gene expression ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A comparison of nucleolide sequences of murine LDH-a and Ldh-c genes and human LDH-A, LDH-B, and LDH-C reveals that mouse Ldh-c has lost the CpG “island” present in the genes for the somatic isozymes. However, the human LDH-C gene has a CpG-rich region of 230 bp surrounding its promoter. Endonuclease sensitivity coupled with polymerase chain reaction (PCR) demonstrate the presence of nine heavily methylated sites in this region in different somatic cells. The same sites are specifically hypomethy-lated in expressing tissues. 3′ sites bordering the CpG-rich region appear to be methylated in both expressing and nonexpressing tissues. Furthermore, the methylated promoter forms a specific complex in vitro with a methyl-DNA binding protein. Evolutionary and functional implications of these observations are discussed. © 1995 Wiley-Liss, Inc.
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    Developmental variability of metallothionein Mtn gene expression in the species of the Drosophila melanogaster subgroup (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 16 (1995), S. 253-263 
    Details
    ISSN: 0192-253X
    Keywords: Metallothionein ; gene expression ; development ; evolution ; Drosophila ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Developmental expression of the Drosophila melanogaster metallothionein Mtn gene has been analysed. Transcripts of this gene accumulate during the vitellogenic phase of oogenesis in a ring of follicular cells at the oocyte-nurse cell margin and in the follicular cells surrounding the oocyte. There is also strong expression of the Mtn gene during the second half of embryogenesis in hemocytes, the endoderm midgut, and Malpighian tubules. A banded expression pattern is observed transiently in the midgut at stage 13. The two Mtn alleles, Mtn1 and Mtn.3, show quantitative differences in their expression patterns. Copper intoxication of flies does not induce ectopic expression of the Mtn gene, but rather leads to over-expression of the gene in the structures where it is normally transcribed. Mtn transcription is not altered in homozygous mutants of four genes (lab, wg, dpp, bap) known to be involved in midgut morphogenesis.Expression of Mtn has been also studied in six other species of the melanogaster subgroup. This analysis demonstrates that regulation of Mtn gene transcription has changed during evolution of the Drosophila lineage. For example, Mtn is expressed specifically in the Malpighian tubules of D. melanogaster while in D. mauritiana and D. sechellia the amnioserosa is a specific location of expression. Nonetheless, expression of Mtn in the midgut is common to the seven species, suggesting a basic role for the MTN protein during embryogenesis in this organ, possibly in the release of metallic ions from vitellogenins. In contrast, two genes also expressed in the embryonic midgut, lab and dFRA display identical patterns in all species of the melanogaster subgroup. The diversity of Mtn patterns in closely related Drosophila species exemplifies the rapid evolution of a gene regulatory system. © 1995 Wiley-Liss, Inc.
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    Masthead (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995) 
    Details
    ISSN: 0192-253X
    Keywords: Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020170301
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    Transmission-ratio distortion of X chromosomes among male offspring of females with skewed X-inactivation (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 198-205 
    Details
    ISSN: 0192-253X
    Keywords: X-chromosome inactivation ; imprinting ; retinoblastoma ; transmission-ratio distortion ; methylation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We have begun a search for heritable variation in X-chromosome inactivation pattern in normal females to determine whether there is a genetic effect on the imprinting of X-chromosome inactivation in humans. We have performed a quantitative analysis of X-chromosome inactivation in lymphocytes from mothers in normal, three-generation families. Eight mothers and 12 grandmothers exhibited evidence of highly skewed patterns of X-chromosome inactivation. We observed that the male offspring of females with skewed X-inactivation patterns were three times more likely to inherit alleles at loci that were located on the inactive X chromosome (Xi) than the active X chromosome (Xa). The region of the X chromosome for which this phenomenon was observed extends from XP11 to -Xq22. We have also examined X-chromosome inactivation patterns in 21 unaffected mothers of male bilateral sporadic retinoblastoma patients. Six of these mothers had skewed patterns of X-chromosome inactivation. In contrast to the tendency for male offspring of skewed mothers from nondisease families to inherit alleles from the inactive X chromosome, five of the six affected males inherited the androgen receptor alleles from the active X chromosome of their mother. © 1995 Wiley-Liss, Inc.
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    Organometallchemie binuclearer 1-Azadien-nickel(0)-Komplexe Bimetallverbindungen mit Ni—Fe-Bindung durch Addition von Pentacarbonyleisen(0) und Nickelalactone durch Ringöffnung cyclischer Anhydride (1995)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 635-639 
    Details
    ISSN: 0044-2313
    Keywords: bimetallic Fe—Ni complexes ; CO2 fixation ; nickelalactones ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Organometallic Chemistry of Binuclear 1-Azadiene-Nickel(0) Complexes: Bimetallic Compounds with a Ni—Fe Bond by Addition of Pentacarbonyl-iron(0) and Nickelalactons by Ring Opening Reaction of Cyclic AnhydridesThe binuclear nickel(0) complexes 1-3, which contain as well bridging 1-azadienes ligands as five or six-membered (N∩N)-chelate rings react at -30°C with Fe(CO)5 to form the bimetallic compounds 4-6, containing a Ni—Fe bond and two carbonyl groups as bridging ligands. The coordination of the [(bpy)Ni(0)] fragment to the olefin part of the 1-azadiene chain in 6 leads to the formation of the trinuclear complex 7, which can storage CO2 at the peripheral position. Succinic acid anhydride or glutaric acid anhydrid undergo a ring opening reaction by reacting with 3 yield nickelalactones upon elimination of CO.
    Notes: Die binuclearen Nickel(0)-Komplexe 1-3, die verbrückende 1-Azadieneinheiten und N∩N-Chelatfünf- oder Sechsringe enthalten, reagieren bei -30°C mit Fe(CO)5 zu den Bimetallcarbonylverbindungen 4-6, die eine Ni—Fe-Bindung und 2 CO-Brückencarbonylliganden aufweisen. Koordination des (bipy)Ni(0)-Fragments an den Olefinteil der 1-Azadienkette 6 liefert den Dreikernkomplex 7, der an der Peripherie CO2 speichert. Bernsteinsäureanhydrid oder Glutarsäureanhydrid reagieren mit 3 unter Ringöffnung und CO-Eliminierung zu Nickelalactonen.
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    Synthesis and Characterization of Mono- and Trinuclear Complexes of BF2+ Bridged Macrocycles (1995)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 654-658 
    Details
    ISSN: 0044-2313
    Keywords: Cobalt complexes ; BF2+ bridged macrocycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthese und Charakterisierung von Ein- und Dreikernkomplexen von BF2+ -verbrückten MacrocyclenDibenzo[e,k]-2,3-bis(hydroxyimino)-1,4-dithia-7,10-diaza-2,3,8,9-tetrahydrocyclododecin (H2L) ist aus 1,2-Bis(o-mercaptoanilino)ethan (4) und (E,E)-Dichlorglyoxim dargestellt worden. Ein Einkernkomplex mit einem Metall: Ligand-Verhältnis von 1:2 ist von Cobalt(III) isoliert worden. Der Cobalt(III)-Komplex von H2L ist mit L′ = 2,6-Lutidin und einem weiteren Chlorion als axialen Liganden dargestellt worden. Ein weiterer Cobalt-Komplex, der BF2+-Brücken enthält, wurde mit dem Bis(E,E)-Liganden erhalten. Von diesem Cobalt(III)-Komplex wurde ein Dreikernkomplex durch Reaktion mit Pd[bis(benzonitril)]Cl2 erhalten. Die Strukturen dieser Komplexe wurden aus analytischen, 1H-, 13C-NMR, IR und massenspektrometrischen Daten geschlossen.
    Notes: Dibenzo[e,k]-2,3-bis(hydroxyimino)-1,4-dithia-7,10-diaza-2,3,8,9-tetrahydrocyclododecine (H2L) has been prepared from 1,2-bis(o-mercaptoanilino) ethane (4) and (E,E)-dichloroglyoxime. A mononuclear complex with a metal: ligand ratio of 1:2 has been isolated for cobalt(III). The CoIII complex of H2L has been prepared with L′ = 2,6-lutidine, and with a chlorine ion as axial ligands. In addition to that, the synthesis of a new cobalt complex which contains BF2+ bridges is achieved with the bis(E,E)-dioxime ligand. The trinuclear complex of this CoIII complex has been obtained by the reaction of BF2+ bridged CoIII complex with Pd[bis(benzonitrile)]Cl2. The structures of these complexes and (E,E)-dioxime were identified by using elemental analysis, 1H and 13C-NMR, IR and MS spectral data.
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    Spectral and Electrochemical Features of some substituted Bis(2-hydroxyaryloximato)Co(II), Ni(II), Pd(II), and Cu(II) Chelates. Crystal and Molecular Structure of Trans-bis(propanone,1-[2-hydroxyphenyl]-oximato)Ni(II) (1995)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 645-653 
    Details
    ISSN: 0044-2313
    Keywords: 2-Hydroxyaryloximatesmetal chelates ; spectroscopy ; electrochemistry ; crystal structure ; Ni(C9H10NO2)2 ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Spektroskopische und elektrochemische Eigenschaften einiger substituierter Bis(2-hydroxyaryloximato)Co(II), Ni(II), Pd(II) und Cu(II)-Chelate. Struktur des Trans-bis(propanon, 1-[2-hydroxyphenyl]-oximato)Ni(II)Die Reaktionsprodukte von fünf 2-Hydroxyaryloximen mit Ni(II), Pd(II) und Co(II) wurden isoliert und anhand ihrer Elementaranalysen, Leitfähigkeiten, magnetischen Momenten und spektroskopischen Daten (IR, 1H-NMR, UV-VIS in Lösung und im festen Zustand) charakterisiert. Das elektrochemische Verhalten wurde mittels zyklisch-voltametrischer Messungen an Quecksilber- und Kohlefaser-Elektroden bestimmt. Der Einfluß der Substituenten auf die Struktur der Chelate und die Elektronendichteverteilung wird abgeschätzt, diskutiert und mit dem Verhalten der entsprechenden Kupfer(II)-Chelate verglichen.Die Struktur der Titelverbindung Trans-bis(propanon, 1-[2-hydroxyphenyl]-oximato)nickel(II), Ni(C9NH10O2)2 wurde röntgenographisch bestimmt, monoklin, P21/n, mit a = 11,894, b = 5,126, c = 13,668 Å, b̃ = 103,72°, Z = 2. Mit der Methode der kleinsten Quadrate wurde eine Absorptionskorrektur bis zu R = 0,03 durchgeführt. Ni liegt in der äquatorialen Ebene und ist von zwei Stickstoff und zwei Sauerstoff in den Abständen 1,884(3) Å bzw. 1,825(2) Å umgeben.
    Notes: The reaction products of five 2-hydroxyaryloximes with Ni(II), Pd(II), and Co(II) have been obtained and characterized by elemental analyses, conductometric measurements, magnetic moment determination, and spectroscopic methods (IR, 1H NMR, electronic absorption in solutions and in solid state). Cyclic voltammetry on mercury and carbon fibre electrodes has been employed to investigate the electrochemical behaviour in DMF solutions. The effect of substituents on the structure of the chelates and the electron distribution is assessed, discussed and compared with the behaviour of the corresponding copper(II) chelates.The structure of the title compound trans-bis(propanone, 1-[2-hydroxyphenyl]-oximato) nickel(II), Ni(C9H10NO2)2 was determined by X-ray diffraction monoclinic system (space group P21/n), a = 11.894, b = 5.126, c = 13.668 Å, b̃ = 103.72°, Z = 2. The structure was refined by full-matrix least squares to a conventional R = 0.03. Ni is on the equatorial plane and surrounded by two nitrogen and two oxygen at distances 1.884(3) Å and 1.825(2) Å, respectively.
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    Zum chemischen Transport von Yttriumtrichlorid mit Aluminiumtrichlorid (1995)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 659-664 
    Details
    ISSN: 0044-2313
    Keywords: Yttrium trichloride ; chemical transport ; gaseous complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chemical Transport of Yttrium Trichloride by Aluminium TrichlorideYttrium trichloride is transported by gaseous aluminium trichloride in the temperature range of 300°C to 700°C from hot to cold. It is followed a gaseous complex YAl4Cl15,g and the enthalpy of formation as well as the standard entropy of the complex from the dependence of the transport rate on the temperature and the initial pressure of Al2Cl6,g.
    Notes: Yttriumtrichlorid ist mit gasförmigem Aluminiumtrichlorid im Temperaturbereich von 300°C bis 700°C von höherer zu tieferer Temperatur chemisch transportierbar. Aus der Abhängigkeit der Transportrate von der Temperatur und vom Gesamtdruck wird ein Gasphasenkomplex YAl4Cl15,g gefolgert und seine Bildungsenthalpie und Standardentropie hergeleitet.
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    Untersuchungen zur thermischen Zersetzung der Ammoniumyttriumhalogenide I. Ammoniumyttriumchloride (1995)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 665-670 
    Details
    ISSN: 0044-2313
    Keywords: Ammonium yttrium chlorides ; thermal decomposition ; thermochemical data ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Investigation on the Thermal Decomposition of Ammonium Yttrium Halides. I. Ammonium Yttrium Chlorides(NH4)3YCl6 decomposes in first step to the solid phase NH4Y2Cl7,s and gaseous NH3,g and HClg. NH4Y2Cl7,s decomposes in a second step to YCl3, NH3 and HCl. The decomposition-pressure-functions are given and from this the enthalpies of formation and the standard entropies of the phases are derived.
    Notes: Die thermische Zersetzung von (NH4)3YCl6,f erfolgt in erster Stufe in Koexistenz mit NH4Y2Cl7,f unter NH3,g und HClg-Abspaltung. NH4Y2Cl7,f zersetzt sich in einer weiteren Stufe in YCl3,f und NH3,g sowie HClg. Die Zersetzungsdruckfunktionen werden als lgp- und lgKp-1/T-Funktionen dargestellt und daraus die Bildungsenthalpien und Standardentropien der Phasen hergeleitet.
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    Cu3SbSe3: Synthese und Kristallstruktur (1995)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 685-688 
    Details
    ISSN: 0044-2313
    Keywords: Copper antimony selenide ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Crystal Structure of Cu3SbSe3The hitherto unknown crystal structure of Cu3SbSe3 has been determined from single crystals. The compound crystallizes in the orthorhombic system, space group Pnma (No. 62), with a = 7.9865(8), b = 10.6138(9) and c = 6.8372(7) Å, V = 579.6(1) Å3, Z = 4. Most remarkable feature of the structure are groups of three cis-edge-sharing tetrahedra [Cu3Se8] which are interlinked to a threedimensional arrangement by SbSe3-units. In contrast to Cu3SbS3 in the temperature range from -180 to 25°C no hints for a phase transition could be detected by means of X-ray- and thermoanalytical methods.
    Notes: Die bisher unbekannte Kristallstruktur von Cu3SbSe3 wurde aus Einkristalldaten ermittelt. Die Verbindung kristallisiert orthorhombisch, RG Pnma (Nr. 62) mit a = 7,9865(8), b = 10,6138(9) und c = 6,8372(7) Å, V = 579.6(1) Å3, Z = 4. Die Struktur zeichnet sich durch Baugruppen [Cu3Se8] aus drei cis-kantenverknüpften Tetraedern aus, die über ihre Liganden mit SbSe3-Gruppen zu einem dreidimensionalen Netzwerk verknüpft sind. Im Gegensatz zu Cu3SbS3 konnten Hinweise auf eine Phasenumwandlung im Temperaturbereich von -180 bis 25°C weder durch röntgenographische noch durch thermoanalytische Untersuchungen gefunden werden.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19956210431
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    Electronic Resource
    Electronic Resource
    Komplexe mit N,N,N′,N′-Tetrakis(2-hydroxybenzyl)ethylendiamin (H4tben). Kristallstruktur von Ti(tben) (1995)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 671-674 
    Details
    ISSN: 0044-2313
    Keywords: N,N,N′,N′-Tetrakis(2-hydroxybenzyl)ethylenediamine ; Complexes of Titanium(IV), Vanadium(IV), Manganese(IV), Tin(IV) ; Mass Spectra ; Mössbauer Data ; Crystal Structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Complexes with N,N,N′,N′-Tetrakis(2-hydroxybenzyl)ethylenediamine (H4tben). Crystal Structure of Ti(tben)The complexes of N,N,N′,N′-tetrakis(2-hydroxybenzyl)-ethylenediamine with titanium(IV), vanadium(IV), manganese(IV), and tin(IV) were synthesized and characterized by mass spectrometry. The Mössbauer date were evaluated for the tin compound. The molecular structure of the titanium(IV) complex was determined by X-ray structural analysis, crystallographic data see “Inhaltsübersicht”.
    Notes: Es wurden die Komplexe von N,N,N′,N′-Tetrakis(2-hydroxybenzyl)ethylendiamin mit Titan(IV), Vanadium(IV), Mangan(IV) und Zinn(IV) hergestellt und massenspektrometrisch charakterisiert. Für die Zinn-Verbindung wurden die Mössbauer-Daten ermittelt. Die Molekülstruktur des Titan(IV)-Komplexes wurde röntgenstrukturanalytisch bestimmt. N,N,N′,N′-Tetrakis(2-hydroxybenzyl)ethylendiaminato(4-)titan(IV): Raumgruppe P21/c (Nr. 14), Z = 4, 3949 Zahl der beobachteten Intensitäten, R = 0,0539, Gitterabmessung bei 20°C; a = 10,447(3) Å, b = 20,668(5) Å, c = 13,420(3) Å, b̃ = 101,93(5) Å
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19956210428
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