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At least 703 records · Page 39Linked to original sources
PubMed1996

Changes in abundance of an abscisic acid-responsive, early cysteine-labeled metallothionein transcript during pollen embryogenesis in bread wheat (Triticum aestivum).

A clone for an embryoid-abundant, early cysteine-labeled metallothionein (EcMt) gene has been isolated from a wheat pollen embryoid cDNA library. The transcript of this gene was only expressed in embryogenic microspores, pollen embryoids, and developing zygotic embryos of wheat. Accumulation of the EcMt mRNA showed a direct and positive correlation with an increase of the plant hormone, abscisic acid (ABA) in developing pollen embryoids. Treating cultures with an inhibitor of ABA biosynthesis, fluridone, suppressed not only ABA accumulation but also the appearance of the EcMt gene transcript and the ability of microspores to form embryoids. These results suggest that the EcMt gene may act as a molecular marker for pollen embryogenesis because ABA biosynthesis is accompanied by the increased expression of the EcMt transcript that coincides with the differentiation of pollen embryoids in wheat anther cultures.

Abscisic Acid↗
PubMed1996

Expression of DC8 is associated with, but not dependent on embryogenesis.

DC8 is a late embryogenesis-abundant (LEA) protein gene isolated from carrot (Daucus carota). Deletion analysis of the DC8 promoter was performed to determine the sequences required for ABA and seed-specific regulation of DC8 transcription. To investigate the mechanism of DC8 expression during seed development, chimeric gene constructs containing DC8 promoter fragments fused to a promoterless beta-glucuronidase gene (DC8:GUS) were introduced into carrot, tobacco (Nicotiana tobacum) and Arabidopsis thaliana plants. Seed-specific DC8 expression patterns was conserved among the three plant species. However, differences among the species in the patterns of DC8 expression in the embryo and endosperm that correlated with differences in the rates of embryo and endosperm growth were found. Lack of correspondence between DC8 activation and embryo development among the seeds of the three species suggests that DC8 expression, which is associated with seed maturation, is not coupled to the embryo development program. The presence of DC8 activity in carrot callus and endosperm is consistent with the notion that DC8 expression is independent of embryo morphogenesis. A similar DC8 activity time-course during callus induction and seed development suggests that explantation and 2,4-D treatment initiates a course of events similar to that in the carrot ovule. After fertilization, two pathways one leading to embryo development and another to seed maturation are initiated, but they are not closely linked. As a result we find DC8, part of the maturation program, being activated at different embryonic stages in different plant species.

Arabidopsis↗
PubMed1995

Evolution of the Group 1 late embryogenesis abundant (Lea) genes: analysis of the Lea B19 gene family in barley.

The highly conserved Group 1 late embryogenesis abundant (Lea) genes are present in the genome of most plants as a gene family. Family members are conserved along the entire coding region, especially within the extremely hydrophilic internal 20 amino acid motif, which may be repeated. Cloning of Lea Group 1 genes from barley resulted in the characterization of four family members named B19.1, B19.1b, B19.3 and B19.4 after the presence of this motif 1, 1, 3 and 4 times in each gene, respectively. We present here the results of comparative and evolutionary analyses of the barley Group 1 Lea gene family (B19). The most important findings resulting from this work are (1) the tandem clustering of B19.3 and B19.4, (2) the spatial conservation of putative regulatory elements between the four B19 gene promoters, (3) the determination of the relative 'age' of the gene family members and (4) the 'chimeric' nature of B19.3 and B19.4, reflecting a cross-over or gene-conversion event in their common ancestor. We also show evidence for the presence of one or two additional expressed B19 genes in the barley genome. Based on our results, we present a model for the evolution of the family in barley, including the 20 amino acid motif. Comparisons of the relatedness between the barley family and all other known Group 1 Lea genes using maximum parsimony (PAUP) analysis provide evidence for the time of divergence between the barley genes containing the internal motif as a single copy and as a repeat. The PAUP analyses also provide evidence for independent duplications of Group 1 genes containing the internal motif as a repeat in both monocots and dicots.

Base Sequence↗
PubMed1991

Differential expression of members of the napin storage protein gene family during embryogenesis in Brassica napus.

S1 nuclease analysis and sub-family-specific oligonucleotide probes were used to characterize the expression during embryogenesis of the napin storage protein gene family of Brassica napus (oilseed rape). The expression of one sub-class represented by the napin gene gNa peaks and declines earlier than the other members of the family. This sub-class was highly expressed representing ca. 20% of napin mRNA at 26 days after anthesis.

2S Albumins, Plant↗
PubMed1994

Expression of sunflower low-molecular-weight heat-shock proteins during embryogenesis and persistence after germination: localization and possible functional implications.

We isolated and sequenced Ha hsp17.9, a DNA complementary (cDNA) of dry-seed stored mRNA that encodes a low-molecular-weight heat-shock protein (LMW HSP). Sequence analysis identified Ha hsp17.9, and the previously reported Ha hsp17.6, as cDNAs encoding proteins (HSP17.6 and HSP17.9) which belong to different families of cytoplasmic LMW HSPs. Using specific antibodies we observed differential expression of both proteins during zygotic embryogenesis under controlled environment, and a remarkable persistence of these LMW HSPs during germination. Immuno-blot analysis of HSP17.9 proteins in two-dimensional gels revealed that the polypeptides expressed in embryos were indistinguishable from LMW HSPs expressed in vegetative tissues in response to water deficit; but they appeared different from homologous proteins expressed in response to thermal-stress. Tissue-print immunolocalization experiments showed that HSP17.9 and HSP17.6 were homogeneously distributed in every tissue of desiccation-tolerant dry seeds and young seedlings under non-stress conditions. These results demonstrate developmental regulation of specific, cytoplasmic, plant LMW HSPs, suggesting also their involvement in water-stress tolerance.

Adaptation, Biological↗
PubMed1996

Expression of abundant mRNAs during somatic embryogenesis of white spruce [Picea glauca (Moench) Voss].

Embryogenic tissues of white spruce [Picea glauca (Moench) Voss] remain in an early developmental stage while cultured on 2,4-dichlorophenoxyacetic acid and N6-benzyladenine, but develop to cotyledonary embryos when these phytohormones are replaced by abscisic acid. Twenty-eight cDNAs were isolated from cotyledonary embryos by differential screening against immature embryo and non-embryonic tissues. Temporal expression patterns of these cDNAs during ABA-stimulated somatic embryo development were observed. This showed that clones could be allocated to various groups, including embryo-abundant, embryo-maturation-induced, and those whose expression was modulated during embryo development, germination or in non-embryogenic tissues. Expression corresponding to these cDNA clones showed that there were various responses to exogenous ABA or polyethylene glycol during a period of 48 h. Analyses of DNA and predicted amino acid sequence revealed that 12 of 28 cDNA clones had no known homologues, while others were predicted to encode different late-embryogenesis-abundant proteins, early methionine-labelled proteins, storage proteins, heat-shock proteins, glycine-rich cell wall protein, metallothionein-like protein and some other metabolic enzymes.

Base Sequence↗
PubMed1994

Further characterization of auxin-regulated mRNAs in hypocotyl sections of mung bean [Vigna radiata (L.) Wilczek]: sequence homology to genes for fatty-acid desaturases and atypical late-embryogenesis-abundant protein, and the mode of expression of the mRNAs.

The amino-acid sequence deduced from the nucleotide sequence of an auxin-regulated gene, ARG1, isolated from auxin-treated sections of mung-bean hypocotyls (Yamamoto et al. 1992, Plant Cell Physiol. 33, 13-20), is 69% identical to that of a delta 15 fatty-acid desaturase from Brassica napus L. that is localized in the endoplasmic reticulum. The ARG1 message is present at high levels in the hook portion of the hypocotyl, the plumule and the root tip of 3-d-old etiolated seedlings. The amino-acid sequence encoded by another auxin-regulated gene, ARG2, is 39% identical to that of an atypical late-embryogenesis-abundant (LEA) protein of cotton, LEA5-A. The ARG2 message is localized in the upper part of hypocotyls. Its abundance increases upon treatment of hypocotyl sections with fusicoccin, as well as with auxin. Determination of the distribution and kinetics of induction of mRNAs transcribed from the five auxin-regulated genes of mung bean, which include Aux22s and SAUR as well as ARG1 and ARG2, shows that they are heterogeneous in their mode of gene expression. The physiological implications of the homology between the two auxin-regulated genes and the genes for previously identified proteins are discussed in the context of auxin-induced elongation of the hypocotyl.

Amino Acid Sequence↗
PubMed1995

Deletion analysis of the Brassica napus cruciferin gene cru 1 promoter in transformed tobacco: promoter activity during early and late stages of embryogenesis is influenced by cis-acting elements in partially separate regions.

To define sequences in the cruciferin gene cru1 promoter of importance for expression, tobacco (Nicotina tabacum L.) plants were transformed with constructs in which the cru1 promoter, in front of the intact cru1 structural gene, was truncated at -1216, -974, -736, -515, -306, -46 and -17 bp relative to the cap-site. Cru1 expression in tobacco seeds was studied by Northern analysis, Western analysis and in-situ hybridizations. Comparisons of the Northern analysis of RNA from tobacco seeds harvested at 18 d after pollination with the Western analysis of protein from mature seeds showed that the regions between -974 to -736 and -306 to -46 were important for the expression of cru1 at an early developmental stage, whereas the regions -736 to -515 and -515 to -306 were important for expression throughout embryogenesis. By investigating the mRNA levels in transgenic seeds at different stages of development, indications were obtained that the two latter regions exerted their effects during the later stages. The in-situ hybridization showed that cru1 mRNA was distributed in parenchyma cells throughout the embryo in seeds expressing constructs -974 and -736. Constructs -515 and -306 showed an expression restricted to the axis or axis and parts of the cotyledons. Sequence comparisons of the cru1 promoter with other storage-protein gene promoters, identified several motifs implicated in gene regulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗
PubMed1995

Unusual sequence and characteristics of a chick-pea seed protein which is regulated by abscisic acid and is similar to late-embryogenesis-abundant proteins.

The cDNA clone GAB-9 was selected from a cDNA gene library constructed from the mRNA of embryonic axes of chick-pea (Cicer arietinum L.) seeds imbibed for 12 h in the presence of abscisic acid. The sequence of this cDNA has an open reading frame of 546 nucleotides that code for 182 amino acids. The polypeptide encoded by the corresponding mRNA is of approx. 20.5 kDa, is basic, and has a broad hydrophobic central region flanked by two hydrophilic regions. The unusual characteristics of this protein, which is similar to late-embryogenesis-abundant proteins, and its possible function are discussed.

Abscisic Acid↗
PubMed1988

Embryogenesis of the connective chordotonal organ in the pedicel of the American cockroach: cell lineage and morphological differentiation.

The ontogenesis of single scolopidia of the chordotonal organ of the American cockroach, Periplaneta americana, takes about 4 days. At 23% embryogenesis (100%=30 d) the first anlagen of scolopidia were identified within the eipithelium by staining with anti-horseradish peroxidase. Reconstruction of the cell lineage of the scolopidial cells was facilitated by two facts: (i) the arrangement of the cells throughout ontogenesis follows a strict pattern, and (ii) daughter cells are recognizable for several hours after mitosis by the cytoplasmic bridge and midbody joining them. When they separate, the midbody undergoes lysosomal degeneration in one of these cells. The earliest recognizable stage is a pair of cells, one of which (cell 1) encloses the other (cell 2) apically. The enclosing cell becomes the accessory cell. Cell 2 divides, yielding the mother cell (cell 3) of two sensory cells which degenerate later, and cell 2'. Cell 2' gives rise to the attachment cell and to cell 2'', which in turn produces the scolopale cell and the mother cell (cell 2'' 2''') of a second pair of sensory cells; the latter are the definitive sensory cells. The end result is the total of 5 cells characteristic of the adult scolopidium. Secretion of the scolopale and cap together with the migration of the sensory cell perikarya into the antennal lumen complete development.

Animals↗
PubMed1990

Molecular analysis of zyg-11, a maternal-effect gene required for early embryogenesis of Caenorhabditis elegans.

The product of the maternally acting gene zyg-11 is required for early embryogenesis of Caenorhabditis elegans. One-cell embryos that lack a functional zyg-11 gene product exhibit an arrest of meiosis at metaphase II, a delay in the formation of pronuclei, unusually vigorous movements of cytoplasm, the formation of multiple pronuclei, incorrect segregation of P granules, and incorrect placement of the first cleavage furrow. We have isolated and sequenced a molecular clone of zyg-11, and shown that microinjection of the cloned DNA can rescue zyg-11 mutations. A transcriptional analysis shows that transcription of the gene is not limited to the female germ-line, despite the strict maternal-effect phenotype of zyg-11 mutations.

Amino Acid Sequence↗
PubMed1976

Elimination of spontaneous and chemically induced chromosome aberrations in mice during early embryogenesis.

NMRI mice (female female) were treated with 0.25 mg/kg body weight Trenimon (2,3,5-triethyleneiminobenzoquinone-1,4) in the preovulatory phase just before ovulation. Then they were mated with untreated males. The female mice were dissected 45 h after application of this mutagen. The preimplantation embryos, being in a 2-cell stage, were flushed out of the oviduct and cultured in vitro for 60 h. Of the cultured embryos 87.7% reached the blastocysts stage in the control series, whereas only 49.7% did so in the experiments. Some of the females were dissected on the 14th day post conception (p.c.) and the number of dead and living implants was determined. Furthermore, the 9.5- and 13.5-day-old embryos were cytologically investigated, to determine the frequency of chromosomal aberrations. Of the unfertilized oocytes 76.2% deriving from mice treated with 0.25 mg/kg Trenimon, were aberrant in the stage of metaphase II (Röhrborn and Hansmann, 1971). Comparing Röhrborn's and Hansmann's results (1971) to our own findings a continuous elimination of chromosome aberration is clearly to be seen during early embryogenesis. The biological selection takes place in the pre- as well as in the early and late postimplantative phase.

Abortion, Spontaneous↗
PubMed1988

Restriction fragment length polymorphisms in diploid and allotetraploid Gossypium: assigning the late embryogenesis-abundant (Lea) alloalleles in G. hirsutum.

We have determined the copy number of 21 genes in an allotetraploid and several diploid species of cotton by gel and dot blot hybridization with cloned cDNAs. The legumin A, legumin B, and all 18 unique Lea (late embryogenesis-abundant) cDNA sequences isolated from the AD allotetraploid Gossypium hirsutum are present in one copy in A, D, E, and F diploid species and in two copies in G. hirsutum. Gel blot analysis of DNAs digested with EcoRI or BamHI usually detects different sized fragments in A and D diploids. Conservation of these restriction fragment length polymorphisms in G. hirsutum allows most of these fragments to be assigned to their respective subgenomes. Furthermore, both subgenomes in G. hirsutum can be distinguished from those in the interfertile allotetraploid G. barbadense. These results show that physical mapping of both sets of chromosomes in an allotetraploid should be possible by segregation analysis.

Alleles↗
PubMed1989

Cloning and analysis of fs(1) Ya, a maternal effect gene required for the initiation of Drosophila embryogenesis.

The maternal effect locus fs(1) Ya is required for the fusion of the apposed sperm and egg pronuclei (syngamy) following fertilization in Drosophila. It is tightly linked to another complementation group, fs(1) Yb, needed for both oogenesis and embryogenesis. We have isolated a set of overlapping cloned sequences in the 3B4-6 region of the X chromosome encompassing the fs(1) Ya-fs(1) Yb region. A single 2.4 kb maternal transcript is encoded within this region, and an 8.5 kb DNA fragment that contains this transcript complements both fs(1) Ya and fs(1) Yb mutations. Northern and in situ hybridization analyses show that the maternal transcript is only present in nurse cells and oocytes beginning in previtellogenic stages, and is evenly distributed in the cytoplasm of 0-2 h syncytial embryos. The transcript is not detected in later stages of embryonic development. This expression pattern correlates closely with the genetic and developmental characteristics expected of the fs(1) Ya gene product.

Animals↗
PubMed1995

Cerebellar dermoid tumor and occipital meningocele in a monozygotic twin: clues to the embryogenesis of craniospinal dysraphism.

A case of monochorionic/monoamnionic twin with discordant occipital developmental malformations is presented. One female twin appeared to have an occipital meningocele with cerebellar aplasia and died immediately after birth. The other twin presented with signs and symptoms of raised intracranial pressure at the age of 7 months. Severe hydrocephalus was present due to an infected intracerebellar dermoid tumor with a contiguous occipital dermal sinus. The clinical and pathological characteristics are described and the different theories concerning twinning, embryogenesis, and dysmorphology in relation to neural tube defects are discussed. Analysis of the features of these monozygotic twins indicates that a meningocele is not a post-neurulation disorder but results from deficient neurulation, probably due to mesodermal insufficiency.

Cerebellar Neoplasms↗
PubMed1979

Studies on the embryogenesis of the tapeworm Cittotaenia variabilis (Stiles, 1895) using transmission and scanning electron microscopy.

The embryogenesis of the tapeworm Cittotaenia variabilis from the oocyte to the oncosphere is followed using scanning electron microscopy (SEM) in conjunction with ethanol cryofracture. Transmission electron micrographs and histochemistry are used to corroborate the inferences drawn from the SEM studies. Evidence is given for oocyte granules, the uterine epithelium, and the outer envelope as sources of components for the outer capsule. The contributions and senescence of the inner envelope and its relationship to the embryophore are given.

Animals↗