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PubMed2006

Expressed sequence tags from loblolly pine embryos reveal similarities with angiosperm embryogenesis.

The process of embryogenesis in gymnosperms differs in significant ways from the more widely studied process in angiosperms. To further our understanding of embryogenesis in gymnosperms, we have generated Expressed Sequence Tags (ESTs) from four cDNA libraries constructed from un-normalized, normalized, and subtracted RNA populations of zygotic and somatic embryos of loblolly pine (Pinus taeda L.). A total of 68,721 ESTs were generated from 68,131 cDNA clones. Following clustering and assembly, these sequences collapsed into 5,274 contigs and 6,880 singleton sequences for a total of 12,154 non-redundant sequences. Searches of a non-identical amino acid database revealed a putative homolog for 9,189 sequences, leaving 2,965 sequences with no known function. More extensive searches of additional plant sequence data sets revealed a putative homolog for all but 1,388 (11.4%) of the sequences. Using gene ontologies, a known function could be assigned for 5,495 of the 12,154 total non-redundant sequences with 13,633 associations in total assigned. When compared to approximately 72,000 sequences in a collated P. taeda transcript assembly derived from >245,000 ESTs derived from root, xylem, stem, needles, pollen cone, and shoot ESTs, 3,458 (28.5%) of the non-redundant embryo sequences were unique and thereby provide a valuable addition to development of a complete loblolly pine transcriptome. To assess similarities between angiosperm and gymnosperm embryo development, we examined our EST collection for putative homologs of angiosperm genes implicated in embryogenesis. Out of 108 angiosperm embryogenesis-related genes, homologs were present for 83 of these genes suggesting that pine contains similar genes for embryogenesis and that our RNA sampling methods were successful. We also identified sequences from the pine embryo transcriptome that have no known function and may contribute to the programming of gene expression and embryo development.

Amino Acid Sequence↗

PubMed1984

Defects in embryogenesis in mutants associated with the antennapedia gene complex of Drosophila melanogaster.

Embryogenesis in individuals with mutations or deficiencies of the genes in the polytene interval 84A-84B1,2 of Drosophila melanogaster was examined using scanning electron microscopy (SEM). The developmental function of this region of chromosome 3 is of particular interest since it contains the Antennapedia Gene Complex (ANT-C), a gene cluster that includes the homoeotic proboscipedia (pb), Sex combs reduced (Scr), and Antennapedia (Antp) loci. The results of SEM studies, clonal analyses, and temperature-shift experiments show that the fushi tarazu (ftz) and zerknullt (zen) genes, which map between pb and Scr, are involved in processes initiated during embryogenesis. The activity of ftz+ appears to be required within the first 4 hr of development for the establishment of the proper number of segments in the embryonic germ band. Individuals with ftz mutations or deficiencies produce only half the normal number of segments. Each of the segments is twice the normal width and is apparently comprised of cells that would normally form two separate metameres. The zen allele is required from about 2-4 hr of embryogenesis. Mutations of this gene result in disturbances of morphogenetic movements during gastrulation. The mutant phenotype is characterized by the absence of the optic lobe, defects in involution of the head segments, and in some cases, failure of germ band elongation. A requirement during embryogenesis for the activities of other genes residing in the 84A-84B1,2 polytene interval is suggested by the phenotypes of individuals heterozygous or homozygous for chromosomal deficiencies. Using the deficiencies Df(3R)AntpNs+R17, Df(3R)Scr, and Df(3R)ScxW+RX2, we examined the effects of deleting the distal portions or all of the 84A-84B1,2 interval. The defects in deletion heterozygotes suggest that the wild-type activity of some gene(s) other than zen, within or just adjacent to the 84B1,2 doublet, is required to complete normal head involution. The deletion of all the loci in the 84A5-84B1,2 interval results in grossly abnormal morphology and morphogenesis of the gnathocephalic appendages of the embryo. From these studies we conclude that mutations and deficiencies of genes associated with the ANT-C have profound effects on embryogenesis. The mutant phenotypes suggest, in addition to ensuring proper segment identity, the wild-type alleles of the 84A-84B1,2 genes are necessary for normal segmentation and elongation of the germ band and normal head involution.

Animals↗

PubMed1979

Independent expression of cardiac type I and II cyclic AMP-dependent protein kinase during murine embryogenesis and postnatal development.

The amount of total cyclic AMP-dependent protein kinase and of the protein kinase isozymes present in mouse heart changes during development. During embryogenesis, the total cardiac protein kinase activity increases most markedly during the 6 days prior to birth. A maximum kinase level is achieved in the 7 day-old neonate, and then activity progressively declines to an adult level approximating that of the mid-embryo. The type II kinase exhibits a moderate increase during late embryogenesis which declines by the time of birth. The type I isozyme increases throughout embryogenesis and the first neonatal week to a maximum specific activity five-fold higher than the mid-embryogenesis level. The isozyme level then falls to an adult activity similar to the mid-embryonic. These changes in isozyme profile are reflected in a changing type I to type II kinase ratio of 1.1 at 13--14 days embryogenesis, 2.4 at birth, 3.0 in the 7 day-old neonates, and 1 in the adult heart. Thus, the two protein kinase isozymes change in association with the developmental process in an independent fashion.

Animals↗

PubMed2004

Antioxidants and total oxyradical scavenging capacity during grass shrimp, Palaemonetes pugio, embryogenesis.

During embryogenesis in grass shrimp the capacity to scavenge oxyradicals increased as measured by the Total Oxyradical Scavenging Capacity (TOSC) assay. The increase in TOSC during embryogenesis was associated with increasing concentrations of a number of antioxidants, including coenzyme Q (ubiquinone), alpha-tocopherol and reduced glutathione. Glutathione concentrations ranged from 0.004 to 0.005 nmol/embryo in early embryo stages and reached concentrations between 0.16 to 0.23 nmol/embryo in late embryo stages. Ascorbate remained essentially constant (0.16-0.20 nmol/embryo) throughout embryogenesis and may provide the preponderance of TOSC during early embryo development. Carotenoids were associated with yolk lipovitellin and these antioxidants decreased as yolk was absorbed during embryogenesis. Astaxanthin and beta-carotene were identified in embryos with astaxanthin always the principal carotenoid. In early embryo stages there are maternally derived antioxidants but as embryogenesis proceeds there is an assembly of a complex antioxidant system by newly formed cells and tissues.

Animals↗

PubMed2005

Metabolic changes in Japanese medaka (Oryzias latipes) during embryogenesis and hypoxia as determined by in vivo 31P NMR.

In vivo (31)P nuclear magnetic resonance spectroscopy (NMR) was used to determine phosphometabolite changes in medaka (Oryzias latipes) during embryogenesis and hypoxia. NMR data were acquired using a flow-through NMR tube perfusion system designed to both deliver oxygenated water to embryos and accommodate a hypoxic challenge. Measurements of embryogenesis at 12- and 24-h intervals throughout 8 days of development (n = 3 per time point, 900 embryos per replicate) and during acute hypoxia (n = 6, 900 embryos at Iwamatsu stage 37 per replicate) were performed via NMR, and replicate samples (n = 4, 250 embryos each) were flash frozen for HPLC analysis. The hypoxic challenge experiment consisted of data acquisition with recirculating water (pre-hypoxic control period; 1 h), without recirculating water (hypoxic challenge; 1 h), then again with recirculating water (recovery period; 1.3 h). Concentrations of ATP, phosphocreatine (PCr), orthophosphate (P(i)), phosphomonoesters (PME), phosphodiesters (PDE), and intracellular pH (pH(i)) were determined by NMR, and ATP, ADP, AMP, GTP, GDP, and PCr were also determined via HPLC. During embryogenesis, [ATP] and [PCr] as determined by HPLC increased from 1-day post fertilization (DPF) levels of 0.93+/-0.08 and 2.48+/-0.21 micromol/mg (dry tissue), respectively, to 7.24+/-0.77 and 15.66+/-1.08 micromol/mg, respectively, by day 8. [ATP] and [PCr] measured by both NMR and HPLC fluctuated over 1-3 DPF, then increased significantly (p<0.05) over 3-8 DPF, while [PME] and [PDE] decreased (p<0.05) throughout embryogenesis. NMR and HPLC measurements revealed 1-3, 4-5, and 6-8 DPF as periods of embryogenesis significantly different from each other (p<0.05), and representing important transitions in metabolism and growth. During hypoxic challenge, [ATP] and [PCr] declined (p<0.05), [PME] and [PDE] decreased slightly, and [P(i)] increased (p<0.05). All phosphometabolites returned to pre-hypoxia concentrations during recovery. The pH(i) decreased (p<0.05) from 7.10+/-0.03 to 6.94+/-0.03 as a result of hypoxia, and failed to return to pre-hypoxic levels within the 1.3-h recovery phase. Results demonstrate the utility of in vivo (31)P NMR to detect significant alterations in phosphorylated nucleotides and phosphometabolites at specific developmental stages during medaka development and that late-stage medaka utilize PCr to generate ATP under hypoxic conditions.

Animals↗

PubMed1999

Characterization of cDNAs expressed in the early stages of microspore embryogenesis in barley (Hordeum vulgare) L.

To gain insight into the molecular events occurring in the very early stages of barley microspore embryogenesis, cDNA clones corresponding to genes differentially expressed during the early stages of microspore culture were isolated and characterized. A cDNA library established from barley microspores cultured for three days was differentially screened against probes generated from freshly isolated microspores. Three cDNAs representing genes not previously identified in barley were isolated. ECA1 (early culture abundant 1) lacked significant homology to known genes or proteins, and the transcript was only expressed during the early stages of culture. Expression was also reduced in low-density control cultures, therefore this gene may play a role in the early stages of barley microspore embryogenesis. ECGST (early culture glutathione S-transferase) had homology to parA-like genes, which are members of a newly discovered group of glutathione S-transferases (GSTs). The protein corresponding to ECGST may be important in protecting cells from oxidative stress during the culture process. ECLTP (early culture lipid transfer protein) had homology to lipid transfer proteins (LTPs), and had an expression pattern similar to that of an LTP known to be a marker of the early stages of embryogenesis in the carrot somatic embryogenesis system. The identification and characterization of the clones isolated in this study provides new information on the events involved in barley microspore embryogenesis.

Amino Acid Sequence↗

PubMed2004

Changes in pectins and MAPKs related to cell development during early microspore embryogenesis in Quercus suber L.

The occurrence and significance of changes in cell wall components and signalling molecules has been investigated during early microspore embryogenesis in cork oak (Quercus suber L.) in relation to cell proliferation and cell differentiation. Microspore embryogenesis has been induced in in vitro anther cultures of Q. suber by the application of a stress treatment of 33 degrees C. After the treatment, microspores at the responsive developmental stage of vacuolate microspore switched towards proliferation and the embryogenesis pathway to further produce haploid plantlets. Ultrastructural and immunocytochemical analysis revealed changes in cell organisation after induction at different developmental stages, the cellular features displayed being in relation to the activation of proliferative activity and the beginning of differentiation in young and late proembryos. Immunogold labelling with JIM5 and JIM7 antibodies showed a different presence of pectin and level of its esterification in cell walls at different developmental stages. Non-esterified pectins were found in higher proportions in cells of late proembryos, suggesting that pectin de-esterification could be related to the beginning of differentiation. The presence and subcellular distribution of Erk 1/2 MAPK homologues have been investigated by immunoblotting, immunofluorescence and immunogold labelling. The results showed an increase in the expression of these proteins with a high presence in the nucleus, during early microspore proembryos development. The reported changes during early microspore embryogenesis are modulated in relation to proliferation and differentiation events. These findings provided new evidences for a role of MAPK signalling pathways in early microspore embryogenesis, specifically in proliferation, and would confer information for the cell fate and the direction of the cell development.

Cell Differentiation↗

PubMed2004

The final step of the ethylene biosynthesis pathway in turnip tops (Brassica rapa): molecular characterization of the 1-aminocyclopropane-1-carboxylate oxidase BrACO1 throughout zygotic embryogenesis and germination of heterogeneous seeds.

In a previous report from the present authors, it was shown that the 1-aminocyclopropane-1-carboxylate (ACC) oxidation may play a crucial role during zygotic embryogenesis of turnip tops seeds. The present study was performed to elucidate the contribution of the silique-wall and seeds in ethylene production during this developmental process. ACC content in the silique wall is only higher than in seeds during the middle phases of zygotic embryogenesis. The ACC-oxidase (ACO) activity peaks in the silique-wall and seeds during the onset of embryogenesis, declining gradually afterwards, being undetectable during desiccation period. Using reverse transcriptase-polymerase chain reaction, one cDNA clone coding for an ACO and called BrACO1, was isolated. The deduced protein for BrACO1 has a molecular weight of 36.8 kDa and a high homology with other crucifer ACOs. The heterologous expression of this cDNA confirmed that BrACO1 is an ACO. The expression of this gene was high during the first phases of silique-wall development, low during the middle phases and undetectable during desiccation. By contrast, BrACO1 transcript was accumulated only in the earliest phases of seed embryogenesis and may participate in the highest ACO activity and ethylene production by seeds at the beginning of embryogenesis. Finally, in this work a correlation between the heterogeneity of Brassica rapa L. cv. Rapa seeds and the ability to oxidize the ACC to ethylene has been demonstrated.

Journal Article↗

PubMed2000

Mouse embryogenesis requires the tissue factor extracellular domain but not the cytoplasmic domain.

Recent studies indicate that tissue factor (TF) acts in embryogenesis, metastasis, and angiogenesis. Three independent groups showed that targeted disruption of the murine TF (mTF) gene results in 90% lethality of mTF null embryos at embryonic days 9. 5-10.5. We have demonstrated that expression of wild-type human TF (hTF) from a minigene rescues the embryonic lethality of mTF null embryos. To investigate the role of TF in embryogenesis, we made mutant hTF minigenes whose products either bound FVII/VIIa at a reduced level or lacked the cytoplasmic domain. Two independent transgenic lines expressing the hTF extracellular domain mutant failed to rescue the embryonic lethality of mTF null embryos, suggesting that FVII/VIIa binding by TF, proteolytic activity by the TF/FVIIa complex, or both were required for embryogenesis. In contrast, two transgenic lines expressing the hTF cytoplasmic domain mutant rescued the embryonic lethality of mTF null embryos, indicating that the cytoplasmic domain of TF was not required for embryogenesis. We propose that TF/FVIIa-dependent extracellular protease activity is required for embryogenesis.

Animals↗

PubMed1981

Pollen embryogenesis to induce, detect, and analyze mutants.

The development of fully differentiated plants from individual pollen grains through a series of developmental phases that resemble embryogenesis beginning with the zygote was demonstrated during the mid-1960's. This technology opened the door to the use of haploid plants (sporophytes with the gametic number of chromosomes) for plant breeding and genetic studies, biochemical and metabolic studies, and the selection of mutations. Although pollen embryogenesis has been demonstrated successfully in numerous plant genera, the procedure cannot as yet be used routinely to generate large populations of plants for experiments. Practical results from use of the technology in genetic toxicology research to detect mutations have failed to fully realize the theoretical potential; further developments of the technology could overcome the limitations. Pollen embryogenesis could be used to develop plants from mutant pollen grains to verify that genetic changes are involved. Through either spontaneous or induced chromosome doubling, these plants can be made homozygous and used to analyze genetically the mutants involved. The success of this approach will depend on the mutant frequency relative to the fraction of pollen grains that undergo embryogenesis; these two factors will dictate population size needed for success. Research effort is needed to further develop pollen embryogenesis for use in the detection of genotoxins under both laboratory and in situ conditions.

Haploidy↗

PubMed2003

[Ultracytochemical localization of calcium and ATPase activity on the 2,4-D induced somatic embryogenesis of Lycium barbarum L].

In order to research the function mechanism of the 2,4-D during the development of plant somatic embryogenesis, we studied its function mechanism and relationship with the space-time distributing of Ca2+ content and ATPase activity on somatic embryogenesis of Lycium barbarum L. The possible effects on 2,4-dichlorophenoxyacetic acid (2,4-D) induced somatic embryogenesis and changes of Ca2+ and ATPase active at different development period of somatic embryogenesis. The result showed: The 2,4-D was a key hormone for induced embryonic state of Lycium barbarum L. The embryonic callus and non-embryonic callus was separately obtained in the medium that contains the auxin 2,4-D and lack 2,4-D. In the present study, we have observed the Ca2+ was more abundant in the further intercellular matrix and on the cell wall at the multi-cellular stage, and Ca2+ was concentrated in the plasma membrane and vacuoles membrane during embryonic cell differentiate and division, to the globular embryo, more Ca2+ was seen in the nucleus. Afterward, it was also observed to be distributed in the thicken cell wall and intercellular matrix. At the same process, the variations of ATPase activity and Ca2+ were highly similar, ATPase activity was mainly located on the plasma membrane in early embryogenic cells. With further development, it was also observed to be distributed in endoplasm, nucleus and vacuoles, with the thickening of embryogenic cell wall, ATPase activity was found in the thickened region and the intercellular space. However, the variations of ATPase activity and Ca2+ have not clearly observed variety dynamics at the nonembryogenic callus, and with further vacuolation of nonembryogenic cell, Ca2+ content and ATPase activity gradually drop. It was indicated there was a closely relationship between the dynamics of Ca2+ and ATPase activity in somatic embryogenesis by 2,4-D induced. And the space-time distribution of Ca2+ and ATPase activity play a key role on signal transmission and the regulation of relevant gene expression.

2,4-Dichlorophenoxyacetic Acid↗

PubMed2005

[The effect of mutation dominant spotting-Yurlovo (KitW-Y) on spermatogenesis, early embryogenesis, and fertility of C57BL/6JY mice].

The effect of mutation KitW-Y found in C57BL/6 mice on fertility, spermatogenesis, and early embryogenesis of mice have been studied. If heterozygotes KitW-Y/+ are crossed with wild-type mice, fertility decreases by 20%. Homozygotes Kitw-Y/KitW-Y and compounds KitW-Y/KitSsm are nonviable. The study of spermatogenesis in KitW-Y/+ mice has demonstrated a negative effect of this mutation on spermatocytes. Histological examination of the testes of mutant males has shown local empty spaces in seminal ducts. Electron microscopic examination of synaptonemal complexes have demonstrated desynapsis disturbance in some nuclei at the diplotene stage of meiotic prophase I. However, these disturbances do not cause a decrease in the number of fertilized oocytes/ova. The decrease in fertility is accounted for disturbances of early embryogenesis. In vivo and in vitro analyses of early embryogenesis have demonstrated that cleavage divisions are asynchronous in KitW-Y/+ heterozygous embryos. Some of these embryos die before implantation, and others cleave more rapidly than wildtype embryos, which give them selective advantage during the postimplantation period of embryogenesis. The pattern of KitW-Y expression during spermatogenesis and embryogenesis mimics potential human pathology, which makes these mutants an interesting and valuable object for genetics and developmental biology.

Animals↗

PubMed1978

[Tumors in animals irradiated during embryogenesis].

In experiments on 465 male and female white non-lineal rats irradiated in their embryonal (7th day--240 rats), organogenesis (14th day--105 rats) and foetal periods of embryogenesis (19th day--120 rats) with 60Co--rays in a dose of 100 r, its actual power 168 r/m, and on 73 control rats the authors have studied the frequency and terms of tumors appearance. A group comprising 219 experimental rats and 53 control animals, died during a period of 200--600 days following their birth, was analysed. Irradiation at different stages of embryogenesis would provide a statistically significant increase in the frequency of tumors and shorten the terms of their appearance. In control animals tumors arose in 16,9% (in 9 of 53 animals). Embryonal and foetal periods of embryogenesis proved to be mostly susceptible as evidenced by the yield of radiation tumors. In animals exposed to irradiation in their embryonal period tumors arose in 64,5% (in 69 of 107 rats), in the foetal period--in 62,8% (in 44 of 70 rats), and during the period of organogenesis--in 42,8% (in 18 of 42 rats). Rats exposed to irradiation in the embryonal and foetal period of embryogenesis developed tumors to the 120--180th day of the experiment, while in the organogenesis period--to the 400th day. Maximum tumor appearance was observed in the last third of the lifetime. Male rats irradiated in the period of embryogenesis developed tumors of the mammary gland and bones, females- ovarian and bone tumors, which were absent in control animals.

Animals↗

PubMed2026

Proteome Unravels Mechanism Differences in Embryogenesis Between Honey Bee Drone and Worker (Apis mellifera L.).

The physiological and social behaviors differ widely between honeybee workers and drones. All the organ rudiments of adult bees are formed during the embryonic stage. The initial molecular bases at the proteomic level for both embryonic developments have been identified, but a comprehensive understanding of the significant events involved in embryonic establishment remains elusive. To elucidate the molecular regulatory mechanisms underlying tissue differentiation during the embryogenesis of drones and workers, we implemented a state-of-the-art approach that combines in-hive inspection and targeted sampling (at nine embryogenesis stages) with high-throughput proteomics technology to investigate the developmental differences. In-hive inspection of hatching timing revealed an average developmental gap of approximately 3.6 h between the two embryos. Furthermore, proteomic analyses indicate that drone and worker embryos adopt distinct developmental strategies. Notably, proteins involved in fatty acid metabolism and key biological pathways related to organ formation-such as the Hedgehog and Wnt signaling pathways-are activated earlier in drones, suggesting that tissue development begins sooner in drone embryos than in workers. Additionally, the upregulation of cytoskeletal proteins and antioxidants in drone embryos likely supports their larger cell size and higher metabolic stress, reflecting distinct molecular characteristics of male development. Ribosomal proteins essential for biosynthetic support remain consistently expressed throughout the late stages in male embryos, indicating that drone embryogenesis lasts longer than that of workers. This work provides novel insights into the molecular foundations of honeybee embryogenesis and lays both theoretical and practical groundwork for future research into the mechanisms driving embryonic development.

Animals↗

PubMed2006

Calcium-regulated fusion of yolk granules during early embryogenesis of Periplaneta americana.

This work reported membrane fusion of yolk granules (YGs) during early embryogenesis of the insect Periplaneta americana (P. americana). We showed that eggs from Day 5 of embryogenesis possess a greater amount of enlarged YGs in comparison with Day 1. Day 5 is also the period when the largest amount of free calcium is found (approximately 17 mM) within the oothecae from early embryogenesis. Treatment of Day 1-YGs fraction with 17 mM Ca2+ resulted in a YG size pattern very similar to the one observed in Day 5 eggs, where enlarged YGs were formed. YG membrane fusion was observed by fluorescent membrane dye transfer from previously labeled small YGs to larger ones and was also visualized by electron microscopy. We also showed that the small "in fusion" YGs seemed to be acidic, suggesting that acidification is correlated with YG membrane fusion. Hence, it was shown that YGs are capable of membrane fusion in a calcium-dependent manner and this process probably occurs in vivo during early embryogenesis of P. americana.

Acids↗

PubMed1993

Expression of alternatively spliced bFGF first coding exons and antisense mRNAs during chicken embryogenesis.

We have identified eight different basic fibroblast growth factor (bFGF or FGF-2) transcripts which can be grouped into three classes expressed during chicken embryogenesis and in specific adult organs. Three of them encode the evolutionarily conserved bFGF proteins. Two additional mRNAs are structurally homologous to the previously isolated Xenopus laevis bFGF antisense transcripts. Their expression during embryogenesis and the inversely proportional amounts of sense and antisense transcripts in several adult organs provide further evidence for a possible regulatory role of the antisense transcripts. Unexpectedly, a novel class of three alternatively spliced bFGF transcripts expressed predominantly during embryogenesis was isolated. Alternative splicing of exon 1 of the open reading frame creates a predicted bFGF isoform containing a completely novel amino-terminal domain. This is the first report describing alternative splicing of the coding region of bFGF. Similar levels of alternatively spliced (alt-bFGF) and canonical bFGF transcripts are expressed during embryogenesis, but in adult organs alt-bFGF transcripts are far less abundant, which suggests roles for the predicted novel bFGF isoform during morphogenesis.

Alternative Splicing↗

PubMed2000

Defined nuclear changes accompany the reprogramming of the microspore to embryogenesis.

The switch of the gametophytic developmental program toward pollen embryogenesis to form a haploid plant represents an important alternative for plant breeding. In the present study, the switch of the gametophytic developmental program toward a sporophytic pathway, "embryogenesis," has been studied in three different plant species, Brassica, tobacco, and pepper. The switch has been induced by stress (heat shock) at the very responsive stage of the microspore, which is the vacuolate period. As a result, the cell nucleus undergoes striking structural changes with regard to late gametophytic development, including alterations of biosynthetic activities and proliferative activity. An enrichment in HSP70 heat-shock protein and in the presence of Ntf6-MAP kinase was observed after inductive treatment in the nuclei during early embryogenesis. This apparently reflected the possible roles of these proteins, specifically the protective role of HSP70 for the nuclear machinery, and signal transduction of Ntf6-MAPK for the entry of cells into proliferation. Importantly, the observed nuclear changes were similar in the three species investigated and represented convenient markers for early monitoring of embryogenesis and selection purposes for obtaining double-haploid plants in plant breeding.

Brassica↗

PubMed1988

The expression of beta 1 and beta 3 tubulin genes of Drosophila melanogaster is spatially regulated during embryogenesis.

In Drosophila beta tubulins are encoded by a small gene family and the four members of this family are differentially expressed. mRNAs transcribed from two of these genes, namely the beta 1 and beta 3 tubulin genes, are abundant during embryogenesis. While the beta 1 tubulin gene is constitutively expressed during development, beta 3 mRNA is restricted to two distinct phases: mid embryogenesis and metamorphosis. The transcription initiation sites are identical in both these stages and comparison of presumptive promoter regions reveals no extensive homologies between the genes. In situ localization shows beta 1 tubulin mRNA to be maternally expressed in the nurse cells of the egg chambers and evenly distributed during early embryogenesis. In contrast, during later stages of embryogenesis beta 1 tubulin transcripts are predominantly expressed in neural derivatives. The beta 3 tubulin gene expression is also spatially regulated, beta 3 mRNA being restricted to the mesoderm.

Animals↗