Kinds Of Embryos Research Articles

The rudimentary embryo: an early angiosperm invention that contributed to their dominance over gymnosperms

AbstractIn this review, we explore the origin of the rudimentary embryo, its relationship to other kinds of plant embryos and its role in the diversification of angiosperms. Rudimentary embryos have a length:width ratio of ≤2.0, and they have organs, including cotyledon(s) and a primary root. A literature survey failed to reveal rudimentary embryos in the pre-angiosperms, suggesting that this kind of embryo is an angiosperm invention. Although proembryos of some gymnosperms and angiosperms have a length:width ratio of ≤2.0, they have not formed meristems or organs. Thus, rudimentary embryos are not proembryos. During the development of rudimentary embryos in monocots and dicots (all non-monocots), the growth pattern of the epicotyledonary cells differs, resulting in differences in the placement of the shoot meristem and in one versus two cotyledons, respectively, but the embryo size is similar. Rudimentary embryos grow inside the seed prior to germination, which is true for linear-underdeveloped embryos, including those in some gymnosperms. Rudimentary embryos served as the starting point for the great diversification of embryos, and ultimately of seeds, in angiosperms, and they are still present in many families of extant angiosperms. The rudimentary embryo is part of the syndrome of changes, including increased speed of pollen germination and pollen tube growth, simplification of the female gametophyte, development of endosperm and elimination of multiple embryo production from each zygote, that distinguish angiosperm seed production from that of gymnosperms. We conclude that the rudimentary embryo was one of many new developments of angiosperms that contributed to their great success on earth.

Differential Effects of Trichostatin A on Mouse Embryogenesis and Development

Trichostatin A (TSA), a histone deacetylase (HDAC) inhibitor, can significantly improve the reprogramming efficiency of somatic cells. However, whether TSA has a detrimental effect on other kinds of embryos is largely unknown because of the lack of integrated analysis of the TSA effect on natural fertilized embryos. To investigate the effect of TSA on mouse embryo development, we analyzed preimplantation and post-implantation development of in vivo, in vitro fertilized, and parthenogenetic embryos treated with TSA at different concentrations and durations. In vivo fertilized embryos appeared to be the most sensitive to TSA treatment among the three groups, and the blastocyst formation rate decreased sharply as TSA concentration and treatment time increased. TSA treatment also reduced the livebirth rate for in vivo fertilized embryos from 56.59 to 38.33% but did not significantly affect postnatal biological functions such as the pups' reproductive performance and their ability for spatial learning and memory. Further analysis indicated that the acetylation level of H3K9 and H4K5 was enhanced by TSA treatment at low concentrations, while DNA methylation appeared to be also disturbed by TSA treatment only at high concentration. Thus, our data indicates that TSA has different effects on preimplantation embryonic development depending on the nature of the embryo's reproductive origin, the TSA concentration and treatment time, whereas the effect of TSA at the indicated concentration on postnatal function was minor.

Martin's peripheral embryo – unique but not a phylogenetic ‘orphan’ at the base of his family tree: a tribute to the insight of a pioneer seed biologist

AbstractAs a tribute to A.C. Martin's classic work on embryos in seeds, we have attempted to gain a better understanding of the peripheral embryo, which puzzled Martin. The peripheral embryo is strongly curved and in contact with the inner surface of the seed coat, and Martin placed it at the base of his family tree of seed phylogeny and called it a ‘phylogenetic orphan’. We evaluated ovule/seed development, kind of embryo and occurrence of perisperm in families with and without a peripheral embryo. All families with a peripheral embryo occur in the Caryophyllales. Seeds with a peripheral embryo have a low cotyledon width:radicle width ratio that coincides with Martin's (full-sized) linear embryo. The peripheral embryo develops in campylotropous and/or amphitropous ovules and is pushed to the side of the seed as the perisperm develops. Linear-full embryos and perisperm are widely distributed across extant angiosperms but are rarely found together, except in core Caryophyllales. The non-core Caryophyllales with endosperm and various kinds of embryos, including the linear-full, diverged before the core Caryophyllales. Thus, the ancestral linear-full embryo appears to have been retained when the core lineage developed campylotropous and/or amphitropous ovules and perisperm. Seeds with a peripheral embryo merit a position on Martin's family tree; however, the position should be a side branch (‘orphan’) slightly above (more advanced than) his linear embryo and not at the base. We conclude that Martin had great insight into the relationships between the kinds of embryos and rightly questioned the position of the peripheral embryo.

RNA-Seq Profiling of Intact and Enucleated Oocyte SCNT Embryos Reveals the Role of Pig Oocyte Nucleus in Somatic Reprogramming.

The specific molecular mechanisms involved in somatic reprogramming remain unidentified. Removal of the oocyte genome is one of the primary causes of developmental failure in cloned embryos, whereas intact oocyte shows stronger reprogramming capability than enucleated oocyte. To identify the reason for the low efficiency of cloning and elucidate the mechanisms involved in somatic reprogramming by the oocyte nucleus, we injected pig cumulus cells into 539 intact MII oocytes and 461 enucleated MII oocytes. Following activation, 260 polyploidy embryos developed to the blastocyst stage whereas only 93 traditionally cloned embryos (48.2% vs. 20.2%, P < 0.01) reached blastocyst stage. Blastocysts generated from intact oocytes also had more cells than those generated from enucleated oocytes (60.70 vs. 46.65, P < 0.01). To identify the genes that contribute to this phenomenon, two early embryos in 2-cell and 4-cell stages were collected for single-cell RNA sequencing. The two kinds of embryos were found to have dramatically different transcriptome profiles. Intact oocyte nuclear transfer embryos showed 1,738 transcripts that were up-regulated relative to enucleated cloned embryos at the 2-cell stage and 728 transcripts that were down-regulated (|log2Ratio| ≥ 5). They showed 2,941 transcripts that were up-regulated during the 4-cell stage and 1,682 that were down-regulated (|log2Ratio| ≥ 5). The most significantly enriched gene ontology categories were those involved in the regulation of binding, catalytic activity, and molecular transducer activity. Other genes that were notably up-regulated and expressed in intact oocyte nuclear transfer embryos were metabolic process. This study provides a comprehensive profile of the differences in gene expression between intact oocyte nuclear transfer embryos and traditional nuclear transfer embryos. This work thus paves the way for further research on the mechanisms underlying somatic reprogramming by oocytes.

Improvement of cloned embryos development by co-culturing with parthenotes: a possible role of exosomes/microvesicles for embryos paracrine communication.

It is well known that embryos cultured in a group can create a microenvironment through secretion of autocrine and paracrine factors that can support and improve the embryos' development when compared to the embryos cultured individually. In this study, we used a co-culture system for paracrine communication between different kinds of embryos. The results showed that co-culture of porcine parthenogenetic (PA) embryos significantly improved the in vitro development of cloned (nuclear transfer, NT) embryos. To reveal the possible mechanism of communication between the two groups, we isolated exosomes/microvesicles (EXs/MVs) from the PA embryos conditioned medium (PA-CM) through differential centrifugation and identified them through transmission electron microscope and immunoflourescence against exosomal/membrane marker CD9. Furthermore, these EXs/MVs were found to contain mRNA of pluripotency genes (Oct4, Sox2, Klf4, c-Myc, and Nanog), and the PKH67-labeled EXs/MVs could be internalized by the NT embryos. The current study demonstrates that cloned embryos' developmental competence can be improved through co-culturing with PA embryos and revealed, for the first time, that in vitro-produced embryos can secrete EXs/MVs as a possible communication tool within their microenvironment. Moreover, it provides a new paradigm for embryo-to-embryo communication in vitro.

Identification of a suitable endogenous control gene in porcine blastocysts for use in quantitative PCR analysis of microRNAs

To obtain reliable results in quantitative PCR (qPCR) reactions, an endogenous control (EC) gene is needed to correct for systematic variations. In this study, a TaqMan low density array was used to quantify the expression levels of microRNA (miRNA) genes in in vivo fertilized, in vitro fertilized, parthenogenetic and somatic cell nuclear transfer blastocysts. The aim was to identify suitable EC genes for the qPCR analysis of miRNAs in porcine blastocysts. The results showed that thirty-six miRNAs were commonly expressed in the four kinds of embryos and the expression levels of eleven miRNAs were similar in the different embryo types (P-value>0.05). These 11 miRNAs were selected as candidate EC genes for further analysis and, of these, miR-16 was identified as the most stable EC gene by the GeNorm (a tool based on a pair-wise comparison model that calculates the internal control genes stability measure and determines the most reliable pair of EC genes) and NormFinder (an excel plug-in that uses an ANOVA-based model to estimate intra- and inter-group variation to indicate the single most stable EC gene) programs. In addition, a cell number normalization method validated miR-16 as a suitable EC gene for use in future qPCR analysis of miRNAs in porcine blastocysts.

Gene expression analysis of bovine blastocysts produced by parthenogenic activation or fertilisation

The processes underlying the very first moments of embryonic development are still not well characterised in mammals. To better define the kinetics of events taking place following fertilisation, it would be best to have perfect synchronisation of sperm entry. With fertilisation occurring during a time interval of 6 to 12h in the same group of fertilised oocytes, this causes a major variation in the time of activation of embryonic development. Bovine parthenogenesis could potentially result in better synchronisation and, if so, would offer a better model for studying developmental competence. In the present study, bovine oocytes were either parthenogenetically activated or fertilised and cultured in vitro for 7 days. Gene expression analysis for those two groups of embryos at early and expanded stages was performed with BlueChip, a customised 2000-cDNA array developed in our laboratory and enriched in clones from various stages of bovine embryo development. The microarray data analysis revealed that only a few genes were differentially expressed, showing the relative similarity between those two kinds of embryos. Nevertheless, the fact that we obtained a similar diversity of developmental stages with parthenotes suggests that synchronisation is more oocyte-specific than sperm entry-time related. We then analysed our data with Ingenuity pathway analysis. Networks of genes involved in blastocyst implantation but also previous stages of embryo development, like maternal-to-embryonic transition, were identified. This new information allows us to better understand the regulatory mechanisms of embryonic development associated with embryo status.

Nymphaeaceae: a basal angiosperm family (ANITA grade) with a fully developed embryo

AbstractRudimentary, broad and small linear embryos occur among members of the most primitive (basal) extant angiosperms, collectively called the ANITA grade (i.e.Amborella,NymphaealesandAustrobaileyales).Amborella(rudimentary) andAustrobaileyales(rudimentary inAustrobaileyaceae,IlliciaceaeandSchisandraceaeand small linear inTrimeniaceae) have kinds of embryos that are known to be underdeveloped; consequently, they must grow inside the seed prior to radicle emergence (germination). On the other hand, it is not known if broad embryos need to grow before radicles can emerge, and whether they are underdeveloped or fully developed. Thus, we addressed the question: ‘Is the broad embryo ofNymphaealesalso underdeveloped?’. Although the embryo length : seed length ratios inNymphaeaAlbert Greenburg,N.capensisvar.zanzibariensisandN.immutabiliswere 0.311, 0.349 and 0.234, respectively, embryos did not grow prior to radicle emergence. Thus, they are fully developed at seed maturity. IfAmborellaandNymphaealesare equally the most basal angiosperms, as some molecular phylogenetic studies indicate, then we must conclude that the broad and rudimentary embryos are equally primitive.

Developmental Capacity of F1 Hybrid Embryos Produced by In Vitro Fertilization between Different Breeds of Japanese Beef Cattle.

The objective of this study was to compare in vitro development to the blastocyst stage of bovine embryos obtained by in vitro fertilization within a breed and between different breeds of cattle. The timing of maturaion division did not differ among oocytes of Japanese Black (JB), Japanese Brown (JBr) and Japanese Shorthorn (JS); 91.5 to 97.5% of the oocytes were at the second metaphase after 21 h of culture. The rate of development to the blastocyst stage was also similar (34.6 to 37.5%) among three kinds of embryos (JB, JBr and JS) that were fertilized in vitro and cultured for 6 to 8 days after insemination. However, significantly higher rates of development to the blastocyst stage were observed (55.0 to 67.2%) when spermatozoa from a JB bull were used for in vitro fertilization of JBr, JS and JP (Japanese Polled) oocytes as compared to the rate of development in control JB embryos (36.7%). Development to the 2- to 4-cell stage did not differ significantly. These results suggest that the effect of heterosis becomes apparent at the blastocyst stage, which might be under the control of zygotic gene activity.

Methylation in fertilised and parthenogenetic preimplantation mouse embryos

DNA methylation is one of the proposed biochemical mechanisms involved in cell differentiation and in genomic imprinting, and DNA methyltransferase (DMT) is a key enzyme in the embryo since mutation of its gene is lethal early in development. In order to verify that non-viability of uniparental embryos was not due to a defect in the regulation of DMT activity, we compared the metabolism of methylation in parthenogenetic embryos (maternal genome) and in fertilised embryos (maternal and paternal genomes). As regards total methylation, estimated by a measure of S-adenosyl methionine (SAM) and S-adenosyl homocysteine (SAH) formation, no significant difference was found between the two kinds of embryos during preimplantation development. Mean values were 4.5 +/- 0.6 fmol (SAM+SAH)/h per 2-cell embryo and 0.40 +/- 0.05 fmol SAH/h per 2-cell embryo, i.e. a SAH/(SAM+SAH) ratio of 9%; there was no detectable SAH formation in blastocysts. The same observation can be made for DMT activity, with mean values of: 7.8 fmol/h per oocyte, 8.5 fmol/h per 2-cell embryo, 6.1 fmol/h per 4-cell embryo, 4.1 fmol/h per morula, and no detectable activity in blastocysts. Total methylation as well as DNA methylation is characterised by a progressive drop in activity during preimplantation development.

Elemental storage in Cucurbita embryos: X-ray microanalysis of magnesium, potassium, calcium, and phosphorus within globoid crystals

Embryos of Cucurbita maxima, Cucurbita andreana, and their reciprocal hybrids store phosphorus, magnesium, potassium, and calcium in distinctive globoid crystals within protein bodies found in cotyledon mesophyll cells. Samples of cotyledon tissue from each of the four kinds of embryos were cryogenically prepared and analyzed by X-ray microanalysis in the frozen state in a scanning electron microscope. The relative proportions of phosphorus, magnesium, potassium, and calcium were expressed as peak to background ratios. Total concentrations of the four elements in whole cotyledons, as measured by neutron activation analysis, were similar to the trends shown by the peak to background ratios for the same elements. This supports the concept that the bulk of the elements P, K, Mg, and Ca in seed tissues is stored in globoid crystals.

Mineral storage in Cucurbita embryos. III. Calcium storage as compared with storage of magnesium, potassium, and phosphorus

Neutron activation analysis was used to measure the concentrations of Mg, K, Ca, and P stored in embryos of Cucurbita maxima, Cucurbita andreana, and their reciprocal hybrids. The embryos contained much higher concentrations of Mg, K, and P than Ca. However, Ca was the only one of the four minerals that was significantly different in the four kinds of embryos. Although all four minerals were stored in higher concentrations in the small root–shoot axes than in the large cotyledons, the proportion of total Ca stored in the axis was higher than the proportion of the other three minerals. P was the predominant mineral in the embryos, K was highest in the seed coats. Differences in mineral concentrations of embryo parts and seed coats indicated a marked selectivity in embryo mineral uptake.

Mineral storage in Cucurbita embryos. II. Calcium storage in reciprocal hybrids of Cucurbita maxima and Cucurbita andreana

Hybrid seeds from crosses between Curcurbita maxima and Curcurbita andreana were similar in weight to the seeds of the maternal parents. The calcium concentrations of the hybrid embryos were significantly different from the Ca concentrations of both parent species and tended toward a level intermediate between that of the two parents. However, the hybrids also differed in Ca concentration from each other and each was more similar to its female parent, indicting some maternal influences on Ca accumulation. There was a significant negative correlation between both embryo weight and embryo length and Ca concentration in hybrid embryos of the large seeds of Cucurbita maxima × Cucurbita andreana. The small seeds of Cucurbita andreana × Cucurbita maxima had embryos in which embryo weight was positively correlated with Ca concentration. In both parent and hybrid embryos the Ca concentration of the axis was higher than the concentration in the cotyledons. The axes of all four kinds of embryos had similar Ca concentrations so that the differences found for whole embryos were due to changes in Ca concentrations in the cotyledons.

Clarification of Taxonomy in the Mesozoa

Stunkard, Horace W. (American Miusetum of Natural History, Central Par-k West at 79th St., New York, N.Y. 10024) 1972. Clarification of Taxonomy in the Mesozoa. Syst. Zool. 21:210-214.-The literature of the Mesozoa is confused because of errors in taxonomy, both in names and dates. Faulty notions concerning the relations between hosts and parasites led to the erection of imaginary genera. Differences of opinion on the limits of generic concepts have resulted in suppression and restoration of generic names. The status of suprageneric categories is similarly confused. Families have been erected, e.g., Heterocyemidae van Beneden, 1882; Orthonectidae Hartmann, 1925; and Heteronectidae Hartmann, 1925, with names that are invalid since they are not based on type genera. The designations and dates given by Grasse in the Traite de Zoologie (1961) are sometimes in error or are otherwise indefinite. The family names Rhopaluridae and Pelmatosphaeridae proposed by Caullery (1961) had been established by Stunkard (1937), where other emendations were made. The Mesozoa, originally regarded as a subphylum intermediate between Protozoa and Metazoa, are secondarily simplified marine organisms derived from free-living progenitors, degraded as a result of parasitism. Their morphology and life cycles, still only partially elucidated, indicate platyhelminth affinities. The rhombozoans and digenetic trematodes are initially parasites of mollusks and the dicyemids arose and evolved with the cephalopods. [Mesozoa.] The name Mesozoa was proposed by E. van Beneden (1876) to denote a group of organisms which he regarded as intermediate between Protozoa and Metazoa. According to Nouvel (1948), the first of these organisms had been discovered by Cavolini (1787) in the renal organs of cephalopod mollusks. They were described by Krohn (1839) and Erdl (1843). Von Kolliker (1849) reported that they had long been known to zoologists and specimens found by him in Octopus vulgaris and Octopus macropus, as well as those reported by other authors from different cephalopods, were regarded as a single species which he named Dicyema paradoxum. The genus, as erected, was monotypic and D. paradoxum is the type species. The generic name, Dicyema, was selected by von Kolliker to denote the fact, first observed by him, that the animals produced two kinds of embryos, which he designated as wurmf6rmig and infusorienartig. Van Beneden (1876) recognized that the vermiform and infusoriform embryos were produced in different individuals, termed 1 Supported by NSF GB-30661 respectively, nematogenes and rhombogenes. He described the cellular organization and traced the development of the vermiform embryos. The anterior cells that form the calotte were termed polars, the two lateral cells between the calotte and the more posterior superficial cells were termed parapolars, while the central cell was regarded as endodermal. Van Beneden restricted the genus Dicyema to parasites of octopuses; those of 0. vulgaris were designated as Dicyema typus; those from 0. macropus as Dicyema clausianum. The name, D. paradoxum, was ignored. Van Beneden believed in strict taxonomic correlation between hosts and parasites. New genera were erected for the dicyemid parasites of each genus of cephalopods other than Octopus and the parasites from the several cephalopod species were regarded as distinct. Species described by Wagener (1857) were redescribed and renamed when assigned to the new genera. Four genera were included in a new family

Variations in Respiratory Enzymes of Embryos in the Loach Fishes

1. Activities of catalase and of succinic dehydrogenase in unfertilized eggs and in embryos of four kinds of loach fishes and those of hybrids derived from the crosses between these fishes were measured.2. The activities per embryo as well as per unit volume of eggs of catalase were greater in embryos of the larger kind and less in those of the smaller kind. The allometry exponent b among the four kinds of embryos in the activity against the egg volume was 1.50.3. The activity of succinic dehydrogenase per unit volume of eggs in unfertilized eggs was alike with each other among the four kinds of fishes but that of embryos was greater in embryos of the smaller kind than in those of the larger kind. The exponent b in the allometry of the activity against the egg volume of unfertilized eggs among the four was 1.04, and that of embryos 0.64.4. The activities of catalase in the hybrid embryos did not differ from those of the maternal control. While the activities per unit volume of eggs of succinic dehydrogenase in the hybrid embryos differed from those of the maternal control as well as those of the paternal control, being intermediate between those in embryos of the parental fishes.5. The relationship among egg size, respiratory rates, activities of these enzymes and temperature adaptation in the loach fishes were discussed.