Zona pellucida in the process of fertilization and mammal embryonal development

In mammals, oocytes, fertilized eggs and pre-implantation embryos are surrounded by an acellular zona pellucida (zona pellucida – ZP). This structure has a fibro-spongy character but it undergoes constant modifications throughout its existence depending on many internal and external factors. ZP consists of glycoproteins marked as ZP1, ZP2, ZP3 and ZP4, the presence of which is species different. ZP1 and probably ZP4 molecules stabilize the fibrillary skeleton of the zona pellucida formed of ZP2 and ZP3 protein polymers which are ligands for specific spermatozoid receptors. The oligosaccharide chains of ZP3 are responsible for the primary attachment of the male gamete which induces the acrosomal reaction. ZP2 enhances this connection by secondary binding to an acrosome-free spermatozoid. Additionally, oviductal specific glycoprotein 1 which plays a role in interspecific oocyte-sperm interactions, appears around the postovulatory oocyte surrounded by ZP. In addition, this protein modifies the resistance of ZP to the action of proteases released as a result of the cortical reaction during polyspermia block. After fertilization, ZP not only protects the egg and then the embryo until implantation, but also has an embryotrophic effect. Understanding the molecular basics of the structure and properties of ZP can significantly improve animal fertility as well as reproductive rates.

De novo mutations in SOD1 are a cause of ALS

ObjectiveThe only identified cause of amyotrophic lateral sclerosis (ALS) are mutations in a number of genes found in familial cases but also in sporadic cases. De novo mutations occurring in a parental gonadal cell, in the zygote or postzygotic during embryonal development can result in an apparently sporadic/isolated case of ALS later in life. We searched for de novo mutations in SOD1 as a cause of ALS.MethodsWe analysed peripheral-blood exome, genome and Sanger sequencing to identify deleterious mutations in SOD1 in 4000 ALS patients from Germany, South Korea and Sweden. Parental kinship was confirmed using highly polymorphic microsatellite markers across the genome. Medical genealogical and clinical data were reviewed and compared with the literature.ResultsWe identified four sporadic ALS cases with de novo mutations in SOD1. They aggregate in hot-spot codons earlier found mutated in familial cases. Their phenotypes match closely what has earlier been reported in familial cases with pathogenic mutations in SOD1. We also encountered familial cases where de novo mutational events in recent generations may have been involved.ConclusionsDe novo mutations are a cause of sporadic ALS and may also be underpinning smaller families with few affected ALS cases. It was not possible to ascertain if the origin of the de novo mutations was parental germline, zygotic or postzygotic during embryonal development. All ALS patients should be offered genetic counselling and genetic screening, the challenges of variant interpretation do not outweigh the potential benefits including earlier confirmed diagnosis and possible bespoken therapy.

Second Branchial Cleft Cyst: A Case Report

Objective: Branchial anomalies are congenital pathologies that are seen in the lateral region of the neck and are generally benign. The branchial clefts develop in the 2nd-7th weeks of fetal life as embryonal development. The branchial anomalies are caused by non-disappearance, abnormal development and, incomplete emerger of the branchial clefts and pockets during embryonal development. The branchial anomalies are generally seen as the cyst. The most common cyst was the second branchial cleft cyst with 95%. Their diameter is usually a few centimeters. Case: A 37-year old male patient was admitted to the hospital because of a swelling on the left side of his neck for four years. Physical examination revealed a mobile cystic mass in level 2 at the upper left jugular region of the neck. The cystic mass and the surrounding lymph nodes were excised and sent to the pathology laboratory. A cystic mass, approximately 5x4x3.5 cm in size, containing cystic areas was observed macroscopically. Microscopically, the cyst was lined with squamous epithelium and contained large lymphocyte groups in the subepithelial area. The case was reported as the branchial cleft cyst. Conclusion: Branchial cleft cysts should be excised before reaching large sizes, as they may cause pain and pressure on the surrounding tissue. In addition, it should be kept in mind that malignancy may develop from branchial cleft cysts, although rare.

The PEDtracker: An Automatic Staging Approach for Drosophila melanogaster Larvae

The post-embryonal development of arthropod species, including crustaceans and insects, is characterized by ecdysis or molting. This process defines growth stages and is controlled by a conserved neuroendocrine system. Each molting event is divided in several critical time points, such as pre-molt, molt, and post-molt, and leaves the animals in a temporarily highly vulnerable state while their cuticle is re-hardening. The molting events occur in an immediate ecdysis sequence within a specific time window during the development. Each sub-stage takes only a short amount of time, which is generally in the order of minutes. To find these relatively short behavioral events, one needs to follow the entire post-embryonal development over several days. As the manual detection of the ecdysis sequence is time consuming and error prone, we designed a monitoring system to facilitate the continuous observation of the post-embryonal development of the fruit fly Drosophila melanogaster. Under constant environmental conditions we are able to observe the life cycle from the embryonic state to the adult, which takes about 10 days in this species. Specific processing algorithms developed and implemented in Fiji and R allow us to determine unique behavioral events on an individual level—including egg hatching, ecdysis and pupation. In addition, we measured growth rates and activity patterns for individual larvae. Our newly created RPackage PEDtracker can predict critical developmental events and thus offers the possibility to perform automated screens that identify changes in various aspects of larval development. In conclusion, the PEDtracker system presented in this study represents the basis for automated real-time staging and analysis not only for the arthropod development.

The PEDtracker: an automatic staging approach for Drosophila melanogaster larvae

The post-embryonal development of arthropod species, including crustaceans and insects, is characterized by ecdysis or molting. This process defines growth stages and is controlled by a conserved neuroendocrine system. Each molting event is divided in several critical time points, such as pre-molt, molt and post-molt, and leaves the animals in a temporarily highly vulnerable state while their cuticle is re-hardening. The molting events occur in an immediate ecdysis sequence within a specific time window during the development. Each sub-stage takes only a short amount of time, which is generally in the order of minutes. To find these relatively short behavioral events, one needs to follow the entire post-embryonal development over several days. As the manual detection of the ecdysis sequence is time consuming and error prone, we designed a monitoring system to facilitate the continuous observation of the post-embryonal development of the fruit fly Drosophila melanogaster. Under constant environmental conditions we are able to observe the life cycle from the embryonic state to the adult, which takes about ten days in this species. Specific processing algorithms developed and implemented in Fiji and R allow us to determine unique behavioral events on an individual level – including egg hatching, ecdysis and pupation. In addition, we measured growth rates and activity patterns for individual larvae. Our newly created RPackage PEDtracker can predict critical developmental events and thus offers the possibility to perform automated screens that identify changes in various aspects of larval development. In conclusion, the PEDtracker system presented in this study represents the basis for automated real-time staging and analysis not only for the arthropod development.