Biology

2173 KiB

Open AccessFeature PaperReview

The Role of Oocyte Organelles in Determining Developmental Competence

by Karen L. Reader, Jo-Ann L. Stanton and Jennifer L. Juengel

Biology 2017, 6(3), 35; https://doi.org/10.3390/biology6030035 - 18 Sep 2017

Cited by 84 | Viewed by 9576

The ability of an oocyte to undergo successful cytoplasmic and nuclear maturation, fertilization and embryo development is referred to as the oocyte’s quality or developmental competence. Quality is dependent on the accumulation of organelles, metabolites and maternal RNAs during the growth and maturation of the oocyte. Various models of good and poor oocyte quality have been used to understand the essential contributors to developmental success. This review covers the current knowledge of how oocyte organelle quantity, distribution and morphology differ between good and poor quality oocytes. The models of oocyte quality are also described and their usefulness for studying the intrinsic quality of an oocyte discussed. Understanding the key critical features of cytoplasmic organelles and metabolites driving oocyte quality will lead to methods for identifying high quality oocytes and improving oocyte competence, both in vitro and in vivo. Full article

(This article belongs to the Special Issue Reproductive Biology)

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1334 KiB

Open AccessFeature PaperReview

MicroRNA Signaling in Embryo Development

by Nicole Gross, Jenna Kropp and Hasan Khatib

Biology 2017, 6(3), 34; https://doi.org/10.3390/biology6030034 - 14 Sep 2017

Cited by 105 | Viewed by 12440

Abstract

Expression of microRNAs (miRNAs) is essential for embryonic development and serves important roles in gametogenesis. miRNAs are secreted into the extracellular environment by the embryo during the preimplantation stage of development. Several cell types secrete miRNAs into biological fluids in the extracellular environment. These fluid-derived miRNAs have been shown to circulate the body. Stable transport is dependent on proper packaging of the miRNAs into extracellular vesicles (EVs), including exosomes. These vesicles, which also contain RNA, DNA and proteins, are on the forefront of research on cell-to-cell communication. Interestingly, EVs have been identified in many reproductive fluids, such as uterine fluid, where their miRNA content is proposed to serve as a mechanism of crosstalk between the mother and conceptus. Here, we review the role of miRNAs in molecular signaling and discuss their transport during early embryo development and implantation. Full article

(This article belongs to the Special Issue Reproductive Biology)

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2049 KiB

Open AccessArticle

Seed Coating with Hydro-Absorbers as Potential Mitigation of Early Season Drought in Sorghum (Sorghum bicolor L. Moench)

by Linda Gorim and Folkard Asch

Biology 2017, 6(3), 33; https://doi.org/10.3390/biology6030033 - 31 Jul 2017

Cited by 5 | Viewed by 5314

Abstract

Climate change poses a threat to sorghum production systems by shifting the onset of the rainy season to a later date, increasing the risk of crop failure during crop establishment. The effects of drought on sorghum during seedling establishment have not been determined. Coating seeds with a water absorbing substance offers a way to buffer the seed against insufficient moisture in the surrounding soil. Seeds of two different sorghum varieties were coated with one of two commercially available hydro-absorbers: Stokosorb^® and Geohumus^®. These hydro-absorbers have the capacity to store water several times their own weight. The aim of this study was to compare the effects of the cited hydro-absorbers on early seedling growth of two sorghum landraces under different levels of soil water deficit. Seedlings were grown for 12 days under three water availability levels (Field capacity (FC), 50% of FC, and 25% of FC). The seedlings under water limited treatments were subsequently re-watered. Biomass, root length, plant height, leaf area, and leaf extension rate were monitored in two-day intervals for 24 days. Coating strongly affected seedling growth both under fully watered and water deficit conditions. Sorghum varieties differed in their responses to both soil water deficit and coating materials. In general, Stockosorb improved seedling performance under water limited conditions particularly by promoting root growth, whereas Geohumus did not. Full article

(This article belongs to the Special Issue Seed Germination and Growth of Plants under Abiotic Stress)

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1688 KiB

Open AccessCommunication

Physical Forces May Cause the HoxD Gene Cluster Elongation

by Spyros Papageorgiou

Biology 2017, 6(3), 32; https://doi.org/10.3390/biology6030032 - 23 Jun 2017

Cited by 6 | Viewed by 4254

Abstract

Hox gene collinearity was discovered be Edward B. Lewis in 1978. It consists of the Hox1, Hox2, Hox3 ordering of the Hox genes in the chromosome from the telomeric to the centromeric side of the chromosome. Surprisingly, the spatial activation of the Hox genes in the ontogenetic units of the embryo follows the same ordering along the anterior-posterior embryonic axis. The chromosome microscale differs from the embryo macroscale by 3 to 4 orders of magnitude. The traditional biomolecular mechanisms are not adequate to comprise phenomena at so divergent spatial domains. A Biophysical Model of physical forces was proposed which can bridge the intermediate space and explain the results of genetic engineering experiments. Recent progress in constructing instruments and achieving high resolution imaging (e.g., 3D DNA FISH, STORM etc.) enable the assessment of the geometric structure of the chromatin during the different phases of Hox gene activation. It is found that the mouse HoxD gene cluster is elongated up to 5–6 times during Hox gene transcription. These unexpected findings agree with the BM predictions. It is now possible to measure several physical quantities inside the nucleus during Hox gene activation. New experiments are proposed to test further this model. Full article

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Biology, Volume 6, Issue 3 (September 2017) – 4 articles

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