Unicellular Zygote Research Articles

A REVIEW ON ROLE OF TRIDOSHA IN HEALTH AND DISEASES

Healthy and unhealthy state of a human being depends on normal and abnormal functional state of Tridosha, considering the physiological importance of Dosha in maintenance of homeostasis of the body. Tridosha have been called as root (Dosha Dhatu Mala Moolam hi Shariram) of the body. All the functions of the body could be explained in terms of Dosha, Dhatu, and Mala. Panchamahabhuta are chief controllers of universe. By Loka purusha saamyavaada existence of entities in universe and living body is similar. Hence controllers in human body must also be Panchabhoutika. Since Dosha are functional representatives of Panchamahabhuta, they are controllers of body functions. They are structurally Panchabhoutika in nature. Synthesis of Dosha is brought about in two stages. Those synthesized in unicellular zygote and impress every cell after differentiation are Prakruta Dosha, which are decisive factors for body characteristics. Those synthesized from food material which control routine body metabolism are called Vaikrata Dosha, which are decisive factors for homeostasis. Both stages are observed in intra uterine as well as extra uterine life. Both these kinds of Dosha work in synergism to carry out all bodily functions. Vatadosha is divided into five types and These types are according to function, chief location etc. Similarly, Pitta as well as Kaphadosha are also divided into five types. Within limits Doshas are maintaining living body, as they maintain homeostasis. Doshas are only and direct responsible factors for genesis of diseases. Even though there are exogenous and endogenous etiological factors in pathogenesis, Ayurveda suggests that any cause leads to vitiation of Dosha in the first place and then next events start for generation of diseases. Doshas control other two entities namely Dhatu and Mala. Aim & Objectives: Observing the role of Doshas in health and disease conditions Materials and Methods: All the classical texts of Ayurveda with available commentaries, published research papers, PUB med, Google scholar, research Gate, subject related data on Internet and other sources were reviewed for the present study Results and Conclusion: The Doshas having the primary role in maintaining health and any disturbance in Doshas will causes disease KEY WORDS: Doshas, Ahara, vihara, Vikruti, vyadhi

Polarity establishment in the plant zygote at a glance.

The complex structures of multicellular organisms originate from a unicellular zygote. In most angiosperms, including Arabidopsis thaliana, the zygote is distinctly polar and divides asymmetrically to produce an apical cell, which generates the aboveground part of the plant body, and a basal cell, which generates the root tip and extraembryonic suspensor. Thus, zygote polarity is pivotal for establishing the apical-basal axis running from the shoot apex to the root tip of the plant body. The molecular mechanisms and spatiotemporal dynamics behind zygote polarization remain elusive. However, advances in live-cell imaging of plant zygotes have recently made significant insights possible. In this Cell Science at a Glance article and the accompanying poster, we summarize our understanding of the early steps in apical-basal axis formation in Arabidopsis, with a focus on de novo transcriptional activation after fertilization and the intracellular dynamics leading to the first asymmetric division of the zygote.

DNA demethylases remodel DNA methylation in rice gametes and zygote and are required for reproduction

Fertilization constitutes a critical step in the plant life cycle during which the gamete genomes undergo chromatin dynamics in preparation for embryogenesis. In mammals, parental chromatin is extensively reprogrammed through the global erasure of DNA methylation. However, in flowering plants it remains unclear whether and how DNA methylation is remodeled in gametes and after fertilization in the zygote. In this study, we characterize DNA methylation patterns and investigate the function of DNA glycosylases in rice eggs, sperm, and unicellular zygotes and during embryogenesis. We found that DNA methylation is locally reconfigured after fertilization and is intensified during embryogenesis. Genetic, epigenomic, and transcriptomic analysis revealed that three rice DNA glycosylases, DNG702, DNG701, and DNG704, demethylate DNA at distinct genomic regions in the gametes and the zygote, and are required for zygotic gene expression and development. Collectively, these results indicate that active DNA demethylation takes place in the gametes and the zygote to locally remodel DNA methylation, which is critical for egg and zygote gene expression and reproduction in rice.

Development of optimal technological approaches for obtaining PGCs in Pushkin breed chickens for further transformation by the CRISPR / Cas9 system

The CRISPR / Cas9 genome editing system is a very convenient and promising method for creating highly productive chickens of meat direction with improved productive qualities. The biological feature of the amniotes structure creates certain difficulties for the an editing structure introduction into a unicellular zygote. The aim of the study is to optimize technological approaches for obtaining PGCs (Primordial Germ Cells) in Pushkin chickens from the Bioresource collection RRIFAGB “Genetic collection of rare and endangered chicken breeds” (Pushkin, St. Petersburg) for further transformation by the CRISPR / Cas9 system. All experiments on chickens were conducted with the ethical approval of the Russian Research Institute of Farm Animal Genetics and Breeding - Branch of the L.K. Ernst Federal Research Center for Animal Husbandry (Protocol Number: 2020–3). The optimal egg weight varied from 55 to 62 grams for incubation It has been revealed that embryos obtained from large eggs from 62 grams or more developed poorly or did not reach the stage of PGCs selection at all. The eggs were incubated with occasional shaking at 37–38 ° C and 65–70% relative humidity. It was better to select PGCs of Pushkin breed chickens on the 3rd day of incubation from the dorsal aorta of embryos (Hamburger Hamilton stage 14). Cell selection was performed using a microinjector (Narishige IM-11-2, Japan). The cells were cultured for 21 days at 37 ° C with 5% CO2. PGCs have been found to reproduce better in a serum-free medium (MEM Non-Essential Amino Acids Solution, Gibco, Thermo Fisher) of a specific chemical composition than in a medium containing serum (Opti-MEM with Chicken Serum, Gibco, Thermo Fisher). The expression of PGCs various genes characteristic was determined by real-time PCR using conservative primer sets.

Bone Morphogenetic Protein (BMP) Signaling in Early Embryonic Development and Cancer-An Overview

Development of a unicellular zygote to a multilayered organised embryo, involves complex growth cues from specific growth factors...

Intracellular dynamics and transcriptional regulations in plant zygotes: a case study of Arabidopsis.

Recent understandings ofArabidopsiszygote. Body axis formation is essential for the proper development of multicellular organisms. The apical-basal axis in Arabidopsis thaliana is determined by the asymmetric division of the zygote, following its cellular polarization. However, the regulatory mechanism of zygote polarization is unclear due to technical issues. The zygote is located deep in the seed (ovule) in flowers, which prevents the living dynamics of zygotes from being observed. In addition, elucidation of molecular pathways by conventional forward genetic screens was not enough because of high gene redundancy in early development. Here, we present a review introducing two new methods, which have been developed to overcome these problems. Method 1: the two-photon live-cell imaging method provides a new system to visualize the dynamics of intracellular structures in Arabidopsis zygotes, such as cytoskeletons and vacuoles. Microtubules form transverse rings and control zygote elongation, while vacuoles dynamically change their shapes along longitudinal actin filaments and support polar nuclear migration. Method 2: the transcriptome method uses isolated Arabidopsis zygotes and egg cells to reveal the gene expression profiles before and after fertilization. This approach revealed that de novo transcription occurs extensively and immediately after fertilization. Moreover, inhibition of the de novo transcription was shown to sufficiently block the zygotic division, thus indicating a strong possibility that yet unidentified zygote regulators can be found using this transcriptome approach. These new strategies in Arabidopsis will help to further our understanding of the fundamental principles regarding the proper formation of plant bodies from unicellular zygotes.

Evolution, Initiation, and Diversity in Early Plant Embryogenesis.

During embryogenesis in plants, cell identities are specified de novo, starting from a single cell. By combining imaging, genomic profiling, and genetics, principles of early plant development have been unraveled in the dicotyledonous plant Arabidopsis. A central emerging question, however, is how well zygotic embryogenesis in Arabidopsis reflects homologous processes in other plant species, including early diverging, non-flowering, and non-seed plants. Here, we consider plant embryogenesis with an emphasis on its evolutionary history, the diverse modes of its initiation, and the concepts in pattern formation among morphologically distinct plant groups. Furthermore, we explore challenges and future directions in plant embryogenesis research.

Single-cell three-dimensional genome structures of rice gametes and unicellular zygotes.

Chromatin conformation capture (3C)1 and high-throughput 3C (Hi-C)2 assays allow the study of three-dimensional (3D) genome structures in cell populations or tissues, based on average proximities of folded DNA. However, differences between cells can be observed only by single-cell measurements that avoid ensemble averaging3-5. To study 3D chromatin organization and dynamics before and after fertilization in flowering plants, we analysed the 3D genomes of rice eggs, sperm cells, unicellular zygotes and shoot mesophyll cells. We show that chromatin architectures of rice eggs and sperm cells are comparable to those of mesophyll cells and are reorganized after fertilization. The rice single-cell 3D genomes display specific features of chromosome compartments and telomere/centromere configuration compared to those in mammalian single cells. Active and silent chromatin domains combine to form multiple foci in the nuclear space. Notably, the 3D genomes of the eggs and unicellular zygotes contain a compact silent centre (CSC) that is absent in sperm cells. CSC appears to be reorganized after fertilization, and may be involved in the regulation of zygotic genome activation (ZGA). Our results reveal specific 3D genome features of plant gametes and the unicellular zygote, and provide a spatial chromatin basis for ZGA and epigenetic regulation in plants.

The Zygotic Transition Is Initiated in Unicellular Plant Zygotes with Asymmetric Activation of Parental Genomes

The zygotic transition, from a fertilized egg to an embryo, is central to animal and plant reproduction. Animal embryos depend upon maternally provided factors until zygotic genome activation (ZGA). In plants, the timing and parental genome contributions to ZGA are unresolved. Here, we use the flowering plant Oryza sativa (rice) to characterize transcriptomes of time-staged isogenic and hybrid zygotes following fertilization. Large-scale transcriptomic changes were observed in unicellular zygotes, including upregulation of S-phase genes, a characteristic of ZGA. The parental contributions to ZGA were highly asymmetric. Zygotic transcription was primarily from the maternal genome and included genes for basic cellular processes. Transcription of the paternal genome was highly restricted but unexpectedly included genes encoding putative pluripotency factors expressed at the onset of ZGA. Thus, distinct transcriptional activities are exhibited by the parental genomes during the initiation of embryogenesis, which presumptively derive from divergent pre-zygotic transcriptional states established in the gametes.

FGF Signaling Emerged Concomitantly with the Origin of Eumetazoans

Complex metazoan bodies require cell-to-cell communication for development, a process often mediated by signaling molecules binding to specific receptors. Relatively few signaling pathways have been recruited during evolution to build multicellular animals from unicellular zygotes. Of these few signaling pathways, one of particular importance is the receptor tyrosine kinase (RTK) pathway. In metazoans, fibroblast growth factors (FGFs) bind to receptors in the RTK family, but the origin of the FGF gene family has so far remained a mystery. Here we show that extant bona fide FGFs most likely originated from proteins bearing an FGF-like domain that arose in a choanoflagellate/metazoan ancestor. We found orthologous genes closely related to FGF in choanoflagellates as well as in many metazoans such as sponges, acoels, protostomes, or nonvertebrate deuterostomes. We also show that these genes have a common evolutionary history with Retinitis Pigmentosa 1 (RP1). Even if some metazoan signaling pathways emerged long before multicellularity, we show that FGFs, like their receptors, originated in a eumetazoan ancestor.

TRAUCO, a Trithorax-group gene homologue, is required for early embryogenesis in Arabidopsis thaliana

Embryogenesis is a critical stage during the plant life cycle in which a unicellular zygote develops into a multicellular organism. Co-ordinated gene expression is thus necessary for proper embryo development. Polycomb and Trithorax group genes are members of evolutionarily conserved machinery that maintains the correct expression patterns of key developmental regulators by repressing and activating gene transcription. TRAUCO (TRO), a gene homologous to the Trithorax group of genes that can functionally complement a BRE2P yeast mutant, has been identified in Arabidopsis thaliana. It is demonstrated that TRO is a nuclear gene product expressed during embryogenesis, and loss of TRO function leads to impaired early embryo development. Embryos that arrested at the globular stage in the tro-1 mutant allele were fully rescued by a TRO expression clone, a demonstration that the tro-1 mutation is a true loss-of-function in TRO. Our data have established that TRO is the first trithorax-group gene homologue in plants that is required for early embryogenesis.

Actin Localization during Fucus Embryogenesis.

Embryogenesis in the Fucales serves as a model system for studying the acquisition of cellular and developmental polarity. Fertilized eggs bear no asymmetry, yet within 16 hours, a developmental axis is formed and the unicellular zygote germinates in accordance with this axis. Microfilaments (actin) play a crucial role in establishing the axis as evidenced by the inhibitory effects of cytochalasins on axis fixation. The cellular content of actin was determined by immunoblot, whereas the localization of F-actin was investigated using the fluorescent probe rhodamine phalloidin. Three isoforms of actin were detected in constant amounts at all developmental stages. Actin networks were found to be distributed uniformly in eggs and zygotes through the period of early zygote development when the polar axis was formed. However, as the polar axis became irreversibly fixed in space, actin was localized at the presumptive germination site by a cytochalasin-sensitive process. This correlation supports the proposal that actin networks play a critical role in axis fixation, and is consistent with our hypothesis that this process involves stabilization of membrane components by transmembrane bridges from the cell wall to the microfilament cytoskeleton.

Spatial reorganization of actin, tubulin and histone mRNAs during meiotic maturation and fertilization in Xenopus oocytes

The distribution of actin, tubulin and histone mRNAs is examined in full grown oocytes, meiotically mature eggs, and unicellular zygotes. For this analysis, oocytes, eggs and embryos were spatially divided into peripheral and central regions of both the animal and vegetal hemispheres, and the relative amounts and concentrations of these RNAs in each region were then determined. The concentration of actin and tubulin mRNAs is greatest in the periphery, whereas histone mRNA exhibits a uniform concentration throughout the oocyte. In the meiotically mature egg, actin mRNA is still concentrated in the periphery and histone mRNA still exhibits a relatively uniform concentration, but the tubulin mRNAs are more concentrated in the central regions. Following fertilization, however, the greatest concentration of mRNAs for actin, histone and tubulin is in the periphery of the zygote. The results demonstrate the existence of a system capable of altering the distributions of these mRNAs as well as a system which distinguishes between different types of mRNA.

Asymmetric movements of cytoplasmic components in Caenorhabditis elegans zygotes

ABSTRACT One of the central problems facing developmental biologists is understanding how the unicellular zygote develops into a multicellular embryo composed of different tissue types. It is now clear that differentiated cell types differ because they express different sets of genes. However, how cells become instructed to express different sets of genes remains a mystery.

VII.—Studies in the morphology of spore-producing members.—No. V. General comparisons and conculsion

In the series of Memoirs of which this is the fifth, and concluding part, the spore-producing members of all the important types of living Pteridophyta have been examined. But it will be well, before entering upon a full discussion of the results, to re-state the general problem of origin of the sporophyte generation, of which those members are so constant a feature. For since 1893, when the first Memoir of this series was written, many fresh facts bearing on the larger question have been disclosed, while a new face has been put upon the whole doctrine of alternation by the recognition of those differences of nuclear state, which have now been found in so many cases to accompany the alternating phases of the life history. Moreover, I am aware of having stated the problem in the first instance so that some of my expressions have been misunderstood, while others require amendment for other reasons. I therefore take the opportunity of first re-stating the general views upon which such data as have been acquired will have their bearing. There are two broad facts which form the basis of the whole discussion: first, that spore-production is the end to which the life of all typical sporophytes tends; and, second, that the sporophyte in all typical cases arises from the unicellular zygote. It is the generation thus initiated by the zygote, and tending uniformly to the production of spores, which is the subject of our present study, but especially the parts of it which produce the spores.