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PubMed2002

Ectopic expression of BABY BOOM triggers a conversion from vegetative to embryonic growth.

The molecular mechanisms underlying the initiation and maintenance of the embryonic pathway in plants are largely unknown. To obtain more insight into these processes, we used subtractive hybridization to identify genes that are upregulated during the in vitro induction of embryo development from immature pollen grains of Brassica napus (microspore embryogenesis). One of the genes identified, BABY BOOM (BBM), shows similarity to the AP2/ERF family of transcription factors and is expressed preferentially in developing embryos and seeds. Ectopic expression of BBM in Arabidopsis and Brassica led to the spontaneous formation of somatic embryos and cotyledon-like structures on seedlings. Ectopic BBM expression induced additional pleiotropic phenotypes, including neoplastic growth, hormone-free regeneration of explants, and alterations in leaf and flower morphology. The expression pattern of BBM in developing seeds combined with the BBM overexpression phenotype suggests a role for this gene in promoting cell proliferation and morphogenesis during embryogenesis.

Amino Acid Sequence↗
PubMed2004

Comparison of application methods to prolong the survival of potential biocontrol bacteria on stored sugar-beet seed.

AIMS: To develop bacterial inoculation treatments on sugar-beet seed that will maintain a commercially acceptable degree of viability for a minimum of 4 months storage at ambient temperature. METHODS AND RESULTS: Single rifampicin-resistant (Rif(+)) strains of both Gram-positive and negative bacterial isolates (mostly pseudomonads) were applied in turn to sugar-beet seed in a comparative study by seed soaking, encapsulation in alginate, pelleting using an inoculated peat carrier or seed priming. The treated seed was assessed for bacterial survival over a time course by plating out homogenized samples onto a selective medium. Priming inoculation offered a significant improvement over all the other application strategies tested. After pelleting with fungicides and drying at 40 degrees C, Pseudomonas marginalis/putida P1W1 maintained populations of >6.6 log(10) CFU g(-1) seed during 4 months storage at 15 degrees C. Subsequent experiments verified a stabilized population under these storage conditions with commercial pellets at <7% moisture content. CONCLUSION: An inoculation method was established which allowed the survival on seed of a Gram-negative bacterium at ambient temperature with little loss in viability. SIGNIFICANCE AND IMPACT OF THE STUDY: This has promising implications for the delivery of beneficial bacteria, especially Gram-negative strains, on sugar beet.

Bacterial Physiological Phenomena↗
PubMedDate not supplied

Tissue engineering of an auricular cartilage model utilizing cultured chondrocyte-poly(L-lactide-epsilon-caprolactone) scaffolds.

To determine the potential development in vivo of tissue-engineered auricular cartilage, chondrocytes from articular cartilage of bovine forelimb joints were seeded on poly(L-lactic acid-epsilon-caprolactone) copolymer scaffolds molded into the shape of a human ear. Copolymer scaffolds alone in the same shape were studied for comparison. Chondrocyte-seeded copolymer constructs and scaffolds alone were each implanted in dorsal skin flaps of athymic mice for up to 40 weeks. Retrieved specimens were examined by histological and molecular techniques. After 10 weeks of implantation, cell-seeded constructs developed cartilage as assessed by toluidine blue and safranin-O red staining; a vascular, perichondrium-like capsule enveloped these constructs; and tissue formation resembled the auricular shape molded originally. Cartilage matrix formation increased, the capsule persisted, and initial auricular configuration was maintained through implantation for 40 weeks. The presence of cartilage production was correlated with RT-PCR analysis, which showed expression of bovine-specific type II collagen and aggrecan mRNA in cell-seeded specimens at 20 and 40 weeks. Copolymer scaffolds monitored only for 40 weeks failed to develop cartilage or a defined capsule and expressed no mRNA. Extensive vascularization led to scaffold erosion, decrease in original size, and loss of contour and shape. These results demonstrate that poly(L-lactic acid-epsilon-caprolactone) copolymer seeded with articular chondrocytes supports development and maintenance of cartilage in a human ear shape over periods to 40 weeks in this implantation model.

Animals↗
PubMed1984

Influence of Sulfur Nutrition on Developmental Patterns of Some Major Pea Seed Proteins and Their mRNAs.

In addition to the marked reduction in legumin synthesis and legumin mRNA levels reported earlier (Chandler, Higgins, Randall, Spencer 1983 Plant Physiol 71: 47-54), pulse labeling of S-deficient Pisum sativum L. seeds showed that a high relative level of total vicilin (vicilin plus convicilin) synthesis was maintained throughout the entire phase of protein accumulation, whereas in nondeficient seeds vicilin synthesis is largely confined to the first half of this phase. Fractionation of pulse-labeled proteins on Na-dodecylsulfate-polyacrylamide gels showed that the synthesis of the M(r) 50,000 family of vicilin polypeptides was increased and greatly extended in S-deficient seeds whereas that of convicilin was slightly reduced. Other changes apparent from pulse-labeling experiments include a depression, to different degrees, in the synthesis of three major albumin polypeptides.The level of the mRNAs for seven major seed proteins was followed throughout development of control and sulfur-deficient seeds. In all cases, the changes in each mRNA closely reflected the pattern of synthesis of its corresponding polypeptide seen by pulse labeling. S-deficient seeds showed an elevated level of M(r) 50,000 vicilin mRNA which remained high throughout seed formation, whereas legumin mRNA levels were greatly reduced at all stages of development.When S-deficient plants were given an adequate supply of sulfate midway through seed development, there was a shift toward the protein synthesis profile characteristic of healthy plants. The synthesis of legumin and two albumins rapidly increased and the synthesis of M(r) 50,000 vicilin declined more slowly. Similar responses were seen in detached, S-deficient seeds supplied directly with adequate sulfate.

Journal Article↗
PubMed2000

The expression of a Vp1-like gene and seed dormancy in Mesembryanthemum crystallinum.

Seeds of the common ice plant (Mesembryanthemum crystallinum) germinate in distinct sub-populations over a time period of more than 4 weeks following imbibition. Distinguishing early (E)- and late (L)-germinating seeds is the expression of a homologue of the transcriptional activator VP1. The deduced amino acid sequence of ice plant VP1 (MVP1) is 39% identical (50% similar) to the sequence of the Arabidopsis VP1 homologue, ABI3. The amount of Mvp1 mRNA, transcribed from a single gene, is different in E and L seeds after water uptake. The levels of the Mvp1 transcripts are very low in immature and mature seeds and they increased during 6 days of imbibition. This expression profile of Mvp1 is different from known Vp1/ABI3-like genes in other plants. Cycloheximide (at 35 microM) abolishes the increase of Mvp1, and L seeds are turned into E seeds, which develop normally when the inhibitor is applied for a short time during imbibition. E seeds treated for the same time period are developmentally impaired and show no radicle elongation. We suggest that the presence and late disappearance of Mvp1 in L seeds is responsible for dormancy and after-ripening of late-germinating ice plant seeds.

Amino Acid Sequence↗
PubMed2003

Genetic parameters for agronomic characteristics. II. Intermediate and advanced stages in a true potato seed breeding population.

The aim of this research was to determine the genetic variation available in some important characteristics for true potato seed breeding in intermediate and advanced stages of a breeding population developed by the Centro Internacional de la Papa. A factorial mating design was used to calculate variance components and heritability at both selection stages. Four males were crossed with four females within each set (4 for intermediate stage and 5 for advanced stage) and their resulting offspring tested across two contrasting locations. Tuber yield and set were the only common characteristics recorded in both selection stages. In the intermediate stage early development characteristics (seed germination plus root and internode length) were also measured. In the advanced breeding material, vine earliness and other reproductive traits (days to flowering, flowering intensity, style length and pollen production) were scored. The heritability for tuber yield (0.35) and tuber set (0.32) in the advanced selection stage was higher than in the intermediate stage (0.26 and 0.13 respectively), which suggest that recombination through more cycles of recurrent selection brought untapped variation for both characteristics in this breeding material. Significant additive genetic variation, and thereby high heritability, was observed for internode length (0.52) in the intermediate selection stage, and for days to flowering (0.53) in the advance stage. Progress through selection may be expected for both characteristics. The heritability for pollen production was intermediate (0.23), while it was low (i.e.< 0.10) for the other characteristics recorded in both populations.

Breeding↗
PubMed2000

Ontogenic emergence of the hematon, a morphogenetic stromal unit that supports multipotential hematopoietic progenitors in mouse bone marrow.

Development of the full repertoire of hematopoietic-lymphopoietic cells from a single stem cell requires specific contacts with stromal cells. The spatio-temporal organization of these cell associations in the bone marrow in ontogeny is, however, not well understood. In the adult, 10% of marrow cells form a cohort of compact aggregates, the hematon. In the hematon mesenchymal cells (Stro-1(+)), perivascular lipocytes (desmin(+)), endothelial cells (CD34(+), Flk-1(+), Sca-1(+)), and macrophages amalgamate with the hematopoietic progenitors long-term culture-initiating cells (LTC-IC), cobblestone area-forming cell (CAFC), high-proliferative-potential colony-forming unit (HPP-CFU), granulocyte-macrophage (GM)-CFU, and burst-forming unit-erythroid (BFU-E). During endochondral ossification of the femur, GM-CFU and day 7 CAFC numbers increased progressively from day 17 of gestation, but primitive, day 35 LTC-IC appeared from postnatal day 2. Unexpectedly, bone marrow (BM) taken between embryonic day 17 and day 5 was unable to support myeloid cell production in long-term cultures or to support day 35 LTC-IC growth. However, a gain in stromal cell competence occurred between days 7 and 10, which was correlated with the emergence of hematon in the BM. Thus, acquisition of hematopoietic competence by BM lags behind for approximately 10 days after the initial hematopoietic cell influx. In the adult, the hematon fraction was 3.7-fold enriched in day 35 LTC-IC over the buffy coat. It produced more GM-CFU and HPP-CFU in myeloid culture and more B cells in lymphopoietic "switch" cultures. It is reported that stromal hematopoietic units named hematons are specific morphogenetic structures that emerge at a well-defined postnatal stage of development in long bones, delineate discrete territories for hematopoietic stem cell seeding and development, embody the most productive hematogenous compartment in the BM, and probably enclose a morphogenetic organizer. (Blood. 2000;96:3763-3771)

Animals↗
PubMed1981

Purification and characterization of mRNA from soybean seeds. Identification of glycinin and beta-conglycinin precursors.

Poly(A)-rich RNA was isolated from developing soybean seeds (Glycine max (L.) Merr.) and fractionated on linear log sucrose gradients. Two major fractions sedimenting at 18 S and 20 S were separated and then purified by further sucrose gradient fractionation. Both fractions were active as messengers when added to a rabbit reticulocyte lysate protein synthesis system. The 18 S fraction caused proteins migrating primarily to the 60,000-dalton region of a sodium dodecyl sulfate gel to be produced, while translation of the 20 S fraction preferentially directed the synthesis of polypeptides similar in size to the alpha and alpha' subunits of beta-conglycinin. Evidence that many of the 60,000-dalton polypeptides were related to glycinin and the high molecular weight 20 S translation products were related to beta-conglycinin was obtained by immunoprecipitation using monospecific antibodies against glycinin and beta-conglycinin, respectively. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of the immunoprecipitated products revealed that the glycinin precursor region contained at least three different size components and that the family of glycinin precursors had larger apparent molecular weight (58,000-63,000) than the disulfide-linked complexes between acidic and basic glycinin subunits (57,000). Unlike the disulfide-linked glycinin complexes which were cleaved by disulfide reduction, glycinin precursors were insensitive to reducing agents. The alpha and alpha' subunits synthesized in vitro also had slightly larger apparent molecular weights than purified alpha and alpha' standards.

Animals↗
PubMed1989

Changes in the zein composition of protein bodies during maize endosperm development.

Zeins, the seed storage proteins of maize, are synthesized during endosperm development by membrane-bound polyribosomes and transported into the lumen of the endoplasmic reticulum, where they assemble into protein bodies. To better understand the distribution of the various zeins throughout the endosperm, and within protein bodies, we used immunolocalization techniques with light and electron microscopy to study endosperm tissue at 14 days and 18 days after pollination. Protein bodies increase in size with distance from the aleurone layer of the developing endosperm; this reflects a process of cell maturation. The protein bodies within the subaleurone cell layer are the smallest and contain little or no alpha-zein; beta-zein and gamma-zein are distributed throughout these small protein bodies. The protein bodies in cells farther away from the aleurone layer are progressively larger, and immunostaining for alpha-zein occurs over locules in the central region of these protein bodies. In the interior of the largest protein bodies, the locules of alpha-zein are fused. Concomitant with the appearance of alpha-zein in the central regions of the protein bodies, most of the beta- and gamma-zeins become peripheral. These observations are consistent with a model in which specific zeins interact to assemble the storage proteins into a protein body.

Immunohistochemistry↗
PubMed1982

Desiccation of Axes of Phaseolus vulgaris during Development of a Switch from a Development Pattern of Protein Synthesis to a Germination Pattern.

Immature seeds of Phaseolus vulgaris removed from the pod at 32 days of development do not germinate unless first subjected to a desiccation treatment. This change from development to germination caused by premature drying is mirrored in the pattern of protein synthesis by the axes. Rehydrated axes from 32-day-developed seeds cease to synthesize proteins that are uniquely associated with development, but instead synthesize some proteins that are similar to those made in the germinating axes from mature dry seeds. Desiccation of 22-day-developed seeds does not lead to their germination, nor does it cause a switch from a developmental to a germination mode of protein synthesis by the axes. It is proposed that desiccation plays a role in permanently suppressing developmental protein synthesis and in inducing germination protein synthesis.

Journal Article↗
PubMed2006

AUXIN RESPONSE FACTOR8 is a negative regulator of fruit initiation in Arabidopsis.

Fruit and seed formation in plants is normally initiated after pollination and fertilization, and, in the absence of fertilization, flowers senesce. In the Arabidopsis thaliana mutant fruit without fertilization, a mutation in AUXIN RESPONSE FACTOR8 (ARF8) results in the uncoupling of fruit development from pollination and fertilization and gives rise to seedless (parthenocarpic) fruit. Parthenocarpy was confirmed in two additional recessive alleles and was caused by mutations within the coding region of ARF8. Genetic experiments indicate that ARF8 acts as an inhibitor to stop further carpel development in the absence of fertilization and the generation of signals required to initiate fruit and seed development. Expression of ARF8 was found to be regulated at multiple levels, and transcriptional autoregulation of ARF8 was observed. Analysis of plants transformed with a transcriptional P(ARF8):beta-glucuronidase (GUS) construct or a translational ARF8:GUS fusion construct displayed distinct developmental regulation of the reporter in floral tissues involved in pollination and fertilization and in the carpel wall. After fertilization, the level of GUS activity declined in the developing seed, while in unfertilized ovules that are destined to senesce, ARF8:GUS expression spread throughout the ovule. This is consistent with a proposed role for ARF8 in restricting signal transduction processes in ovules and growth in pistils until the fruit initiation cue.

Alleles↗
PubMed1987

Soybean seed growth in response to long-term exposures to differing oxygen partial pressures.

Short-term studies have indicated that alterations in the oxygen partial pressure (pO(2)) around developing soybean (Glycine max [L.] Merr.) seeds may alter seed growth characteristics. A 2-year field study was undertaken to determine the effects on seed development of long-term exposures of individual pods to either sub-ambient or supra-ambient pO(2). Pod chambers were used through which fixed pO(2) were continuously flowed throughout seed development. No effects on maturity date were observed from exposures to either sub-ambient or supra-ambient pO(2). On the other hand, seed weight was reduced by 0.10 pO(2) in both years of the study implicating an O(2) limitation on seed growth rate at this fairly high pO(2). In 1 of the 2 years, supra-ambient pO(2) resulted in increased seed weight.

Journal Article↗
PubMed2001

FIERY1 encoding an inositol polyphosphate 1-phosphatase is a negative regulator of abscisic acid and stress signaling in Arabidopsis.

The plant hormone abscisic acid (ABA) plays a wide range of important roles in plant growth and development, including embryogenesis, seed dormancy, root and shoot growth, transpiration, and stress tolerance. ABA and various abiotic stresses also activate the expression of numerous plant genes through undefined signaling pathways. To gain insight into ABA and stress signal transduction, we conducted a genetic screen based on ABA- and stress-inducible gene transcription. Here we report the identification of an Arabidopsis mutation, fiery1 (fry1), which results in super-induction of ABA- and stress-responsive genes. Seed germination and postembryonic development of fry1 are more sensitive to ABA or stress inhibition. The mutant plants are also compromised in tolerance to freezing, drought, and salt stresses. Map-based cloning revealed that FRY1 encodes an inositol polyphosphate 1-phosphatase, which functions in the catabolism of inositol 1, 4, 5-trisphosphate (IP(3)). Upon ABA treatment, fry1 mutant plants accumulated more IP(3) than did the wild-type plants. These results provide the first genetic evidence indicating that phosphoinositols mediate ABA and stress signal transduction in plants and their turnover is critical for attenuating ABA and stress signaling.

Abscisic Acid↗
PubMed2001

Cultural requirements for in vitro seed germination, protocorm growth and seedling development of Geodorum densiflorum (Lam.) Schltr.

Effects of different nutrient solutions, organic supplements and plant growth regulators on in vitro seed germination and protocorm development of Geodorum densiflorum (Lam.) Schltr. were studied. Seed germination was very high (up to 96%) in all the basal media, with Knudson's C and half-strength Murashige & Skoog being slightly more productive than Vacin & Went. Application of organic supplements and NAA had little effect on germination, but BAP proved inhibitory. After germination, protocorms exhibited a clear preference for peptone and NAA for much faster growth, while BAP resulted in stunted growth. Beside normal development, disorganisation of protocorms, followed by callusing occurred in presence of peptone and NAA. The calli were compact with limited growth and frequently regenerated protocorm like bodies. Development of seedlings was preceded by an intermediary rhizome phase. Growth of rhizomes was slow in the plant growth regulator free medium and about 15 months of culture was required for seedling formation. However, it was possible to hasten the process by 8-10 months with the employment of NAA, which also enhanced the number of seedlings per protocorm through axillary branching. Combined application of high BAP and low NAA was also useful for high rate of seedling formation.

Culture Media↗
PubMed1978

Staphylococcus aureus bacteremia: relationship between formation of antibodies to teichoic acid and development of metastatic abscesses.

Of 50 patients with bacteremia due to Staphylococcus aureus but without clinical evidence of endocarditis, 24 developed antibodies to the cell wall teichoic acid of S. aureus that were demonstrable by counterimmunoelectrophoresis. However, only 16 of the 24 patients developed titers of antibodies high enough for detection by passive gel diffusion. Eleven of the 16 patients developed evidence of complications due to metastatic infection. In contrast, of the 34 patients who were antibody-negative by gel diffusion, only one patient developed evidence of metastatic seeding. Thus, the development of antibodies to teichoic acid at a level detectable by the gel diffusion technique is regularly associated with complicated infections due to S. aureus that require more prolonged therapy, whereas bacteremic patients not developing such an antibody response rarely develop complications and may be treated with a two-week course of therapy.

Abscess↗
PubMed1993

Pigmented Soybean (Glycine max) Seed Coats Accumulate Proanthocyanidins during Development.

The dominant I gene inhibits accumulation of anthocyanin pigments in the epidermal layer of soybean (Glycine max) seed coats. Seed-coat color is also influenced by the R locus and by the pubescence color alleles (T, tawny; t, gray). Protein and RNA from cultivars with black (i,R,T) and brown (i,r,T) seed coats are difficult to extract. To determine the nature of the interfering plant products, we examined seed-coat extracts from Clark isogenic lines for flavonoids, anthocyanins, and possible proanthocyanidins by thin-layer chromatography. We show that yellow seed-coat varieties (I) do not accumulate anthocyanins (anthocyanidin glycosides) or proanthocyanidins (polymeric anthocyanidins). Mature, black (i,R,T) and imperfect-black (i,R,t) seed coats contained anthocyanins, whereas mature, brown (i,r,T) and buff (i,r,t) seed coats did not contain anthocyanins. In contrast, all colored (i) genotypes tested positive for the presence of proanthocyanidins by butanol/ HCl and 0.5% vanillin assays. Immature, black (i,R,T) and brown (i,r,T) seed coats contained significant amounts of procyanidin, a 3[prime],4[prime]-hydroxylated proanthocyanidin. Immature, black (i,R,T) or brown (i,r,T) seed-coat extracts also tested positive for the ability to precipitate proteins in a radial diffusion assay and to bind RNA in vitro. Imperfect-black (i,R,t) or buff (i,r,t) seed coats contained lesser amounts of propelargonidin, a 4[prime]-hydroxylated proanthocyanidin. Seed-coat extracts from these genotypes did not have the ability to precipitate protein or bind to RNA. In summary, the dominant I gene controls inhibition of not only anthocyanins but also proanthocyanidins in soybean seed coats. In homozygous recessive i genotypes, the T-t gene pair determines the types of proanthocyanidins present, which is consistent with the hypothesis that the T locus encodes a microsomal 3[prime]-flavonoid hydroxylase.

Journal Article↗