Centrosome structure and function is altered by chloral hydrate and diazepam during the first reproductive cell cycles in sea urchin eggs

Benzodiazepine Interference with Fertility and Embryo Development: A Preliminary Survey in the Sea Urchin Paracentrotus lividus

Psychotropic drugs and benzodiazepines are nowadays among the primary substances of abuse. This results in a large and constant release into aquatic environments where they have potentially harmful effects on non-target organisms and, eventually, human health. In the last decades, evidence has been collected on the possible interference of benzodiazepines with reproductive processes, but data are few and incomplete. In this study, the possible negative influence of delorazepam on fertilization and embryo development has been tested in Paracentrotus lividus, a key model organism in studies of reproduction and embryonic development. Sperm, eggs, or fertilized eggs have been exposed to delorazepam at three concentrations: 1 μg/L (environmentally realistic), 5 μg/L, and 10 μg/L. Results indicate that delorazepam reduces the fertilizing capacity of male and female gametes and interferes with fertilization and embryo development. Exposure causes anatomical anomalies in plutei, accelerates/delays development, and alters the presence and distribution of glycoconjugates such as N-Acetyl-glucosamine, α-linked fucose, and α-linked mannose in both morulae and plutei. These results should attract attention to the reproductive fitness of aquatic species exposed to benzodiazepines and pave the way for further investigation of the effects they may exert on human fertility. The presence of benzodiazepines in the aquatic environment raises concerns about the reproductive well-being of aquatic species. Additionally, it prompts worries regarding potential impacts on human fertility due to the excessive use of anxiolytics.

Kinesin family member 3A induces related diseases via wingless-related integration site/β-catenin signaling pathway

Kinesin family member 3A is an important motor protein that participates in various physiological and pathological processes, including normal tissue development, homeostasis maintenance, tumor infiltration, and migration. The wingless-related integration site/β-catenin signaling pathway is essential for critical molecular mechanisms such as embryonic development, organogenesis, tissue regeneration, and carcinogenesis. Recent studies have examined the molecular mechanisms of kinesin family member 3A, among which the wingless-related integration site/β-catenin signaling pathway has gained attention. The interaction between kinesin family member 3A and the wingless-related integration site/β-catenin signaling pathway is compact and complex but is fascinating and worthy of further study. The upregulation and downregulation of kinesin family member 3A influence many diseases and patient survival through the wingless-related integration site/β-catenin signaling pathway. Therefore, this review mainly focuses on describing the kinesin family member 3A and wingless-related integration site/β-catenin signaling pathways and their associated diseases.

The functional significance of centrosomes in mammalian meiosis, fertilization, development, nuclear transfer, and stem cell differentiation

Centrosomes had been discovered in germ cells and germ cells continue to provide excellent but also challenging material in which to study complex centrosomal dynamics. The present review highlights the importance of centrosomes for meiotic spindle integrity and the susceptibility of meiotic spindle centrosomes to aging and drugs or toxic agents which may be associated with female infertility, aneuploidy, and developmental abnormalities. We discuss cell and molecular aspects of centrosomes during fertilization, a critical stage in which centrosomes play crucial roles in precisely organizing the sperm aster that allows apposition of male and female genomes followed by formation of the zygote aster that is important for the formation of the bipolar spindle apparatus during cell division. Development of an embryo involves sequential cell divisions in which centrosomes play a critical role in establishing asymmetry that allows differentiation of cells and targeted signal transductions for the developing embryo. Asymmetric centrosome dynamics are also critical for stem cell division to maintain one daughter cell as a stem cell while the other daughter cell undergoes centrosome growth in preparation for differentiation. This review also discusses the complex interactions of somatic cell centrosomes with the recipient oocyte in reconstructed (cloned) embryos in which centrosome remodeling is crucial to fulfill functions that are carried out by the zygote centrosome in fertilized eggs. We close our discussion with a look at centrosome dysfunctions and implications for male fertility and assisted reproduction.

A synthetic derivative of plant allylpolyalkoxybenzenes induces selective loss of motile cilia in sea urchin embryos

Polyalkoxybenzenes are plant components displaying a wide range of biological activities. In these studies, we synthesized apiol and dillapiol isoxazoline analogues of combretastatins and evaluated their effect on sea urchin embryos. We have shown that p-methoxyphenyl isoxazoline caused sea urchin embryo immobilization due to the selective excision of motile cilia, whereas long immotile sensory cilia of apical tuft remained intact. This effect was completely reversed by washing the embryos. The compound did not alter cell division, blastulae hatching, and larval morphogenesis. In our hands, the molecule would serve as a convenient tool for in vivo studying morphogenetic processes in the sea urchin embryo. We anticipate that both the assay and the described derivative could be used for studies in ciliary function in embryogenesis.

Microtubule assembly after treatment of pig oocytes with taxol: correlation with chromosomes, gamma-tubulin, and MAP kinase

In this study, taxol was used as a tool to study the correlation of microtubule assembly with chromosomes, gamma-tubulin and phosphorylated mitogen-activated protein (MAP) kinase in pig oocytes at different maturational stages. Taxol treatment did not affect meiotic resumption and chromosome condensation but inhibited/disrupted chromosome alignment at the metaphase plate and bipolar spindle formation and thus meiotic progression. Microtubules were co-localized with chromosomes and were found to emanate from the chromosomes in taxol-treated oocytes, suggesting that chromosomes may serve as a source of microtubule organization. In addition, the concentric emanation of microtubules within the chromosome-surrounded area in taxol-treated oocytes suggests that microtubule emanation from the chromosomes may be directed by other microtubule-organizing material. The formation of one large spindle or >/=2 spindles in oocytes after taxol removal shows that minus end microtubule-organizing material can be normally located on both sides of chromosomes only when the chromosomes are aligned on the metaphase plate. The co-localization of gamma-tubulin and phosphorylated MAP kinase with microtubule assembly in both control and taxol-treated oocytes suggests that these two proteins are associated microtubule-nucleating material in pig oocytes. However, Western blot analysis showed that neither cytoplasmic microtubule aster formation nor extensive microtubule assembly in the chromosome region induced by taxol was caused by super-activation of MAP kinase. Taxol also induced microtubule assembly depending on chromosome distribution in the first polar body. The results suggest that chromosomes are always co-localized with microtubules and that emanation of microtubules from the chromosomes may be regulated/directed by microtubule-organizing material including gamma-tubulin and phosphorylated MAP kinase in pig oocytes.

The contribution of epigenetic changes to abnormal centrosomes and genomic instability in breast cancer

The centrosome is the major microtubule organizing center of the cell and as such it plays an important role in cytoskeletal organization and in the formation of the bipolar mitotic spindle. Centrosome defects, characterized by abnormal size, number, and microtubule nucleation capacity, are distinguishing features of most high grade breast tumors and have been implicated as a possible cause for the loss of tissue architecture and the origin of mitotic abnormalities seen in solid tumors in general. Centrosome defects arise through uncoupling of centriole duplication and the cell cycle as a result of either genetic alterations or through physical or chemical perturbation of centrosome function. Centrosomes manifest unique epigenetic properties whereby positional or structural information can be propagated through somatic cell lineages by way of nongenetic pathways. Because aberrant centrosome function can result in chromosomal instability, these properties may have important implications for the origin of malignant breast tumors.

From fertilization to cancer: the role of centrosomes in the union and separation of genomic material

Centrosomes play crucial roles in the union of sperm and egg nuclei during fertilization and in the equal separation of genomic material during cell division. While many studies in recent years have focused on the molecular composition of centrosomes, this article focuses on the structural behavior of centrosomes and on factors that play a role in centrosome functions under normal, artificially altered, and abnormal conditions. We review here how studies in the classic sea urchin egg model have contributed to our knowledge on the centrosome cycle within the cell cycle, on compaction and decompaction of centrosomal material, and on the contributions of maternal and paternal centrosomes during fertilization. Centrosome material is activated in unfertilized eggs by increasing pH with ammonium and by increasing calcium with the ionophore A23187, which are conditions that are normally induced by sperm. D(2)O and taxol also induce centrosome aggregation in the unfertilized egg. Maternal and paternal centrosome material both contribute to the formation of a functional centrosome but the formation of a bipolar centrosome requires material from the paternal centrosome. Fertilization of taxol-treated eggs reveals that the male centrosome possesses the capability to attract maternal centrosome material. When pronuclear fusion of the male and female pronuclei is inhibited with agents such as the disulfide reducing agent dithiothreitol (DTT) a bipolar mitotic apparatus is formed from the paternal centrosome. Furthermore, one centrosome of the bipolar mitotic apparatus is capable of organizing an additional half spindle that attaches to the female pronucleus indicating a functional and perhaps structural connection between centrosomes and chromatin. Sea urchin eggs are also useful to study centrosome abnormalities and consequences for the cell cycle. While classic studies by Theodor Boveri have shown that dispermic fertilization will result in abnormal cell division because of multiple centrosomes contributed by sperm, abnormal cell division can also be induced by chemical alterations of centrosomes. Compaction and decompaction of centrosome structure is studied using chloral hydrate or the chaotropic agent formamide, which reveals that centrosomes can be chemically altered to produce mono- or multipolar abnormal mitosis and unequal distribution of genomic material upon release from formamide. The patterns of abnormal centrosome reformations after recovery from formamide treatment resemble those seen in cancer cells which argues that structural defects of centrosomes can account for the formation of abnormal mitosis and multipolar cells frequently observed in cancer. In summary, the sea urchin model has been most useful to gain information on the role of centrosomes during fertilization and cell division as well as on adverse conditions that play a role in centrosome dysfunctions and in disease.