Biology subjects

Com, E.

Publications and source records attributed to Com, E..

6 recordsLinked to original sources

bioRxiv2026

An internal scaffold supports microtubule architectural diversity in Xenopus spermatids

During spermiogenesis, early round spermatids differentiate into specialized spermatozoa through an extensive reshaping of the nucleus driven by coordinated cytoskeletal and chromatin-based mechanisms. In mammals, this process critically relies on the transient manchette, a microtubule-based structure that remodels the spermatid nucleus and serves a track to transport material required for flagellum assembly. However, the existence, organization, and molecular composition of such a structure in other vertebrates have remained poorly investigated. Here, we establish that an organized microtubule network is present in Xenopus spermatids and shares key architectural and molecular hallmarks of the mammalian manchette. We further uncover a large structural heterogeneity of spermatid microtubules, with variable protofilament numbers, skew angles, and lattice organizations. We reveal the presence of a Spaca9-Saxo2 internal scaffold in spermatid microtubules suggesting an internal reinforcement mechanism necessary for extensive nuclear reshaping and cytoplasm remodeling.

cell biology↗

bioRxiv2026

The cuticle lamellae responsible for structural coloration in red algae display common features with the metazoan extracellular matrix

Structural coloration is a physical phenomenon observed in many living organisms, including seaweeds, via the formation of highly organized nanostructures. Although the deposition of multilayer thin-film in the extracellular matrix (ECM) is a widespread characterized system, enabling light interference, to date such lamellae have only been described in the cuticle of red algae belonging to the Gigartinaceae family within macroalgae. Here, we determine the composition of the multilayered cuticle components in the model species Chondrus crispus (Rhodophyta), using genomic, transcriptomic, proteomic, metabolomic and analytical profiling of carbohydrates. The complex structural assembly revealed common features with the ECM of animals. The carbohydrate fraction consists of a complex mixture of ECM carrageenans and glycosaminoglycan-like structures. A major von Willerbrand factor A domain (VWA) protein plays a critical role for the adhesion of macromolecules, including protein-protein interactions and to sulfated polysaccharides. We propose the name of Lamellae Cohesive Protein (LCP) regarding the alternate distribution of chemically distinct constituents within the cuticle. For the first time, we identified major proteins of the algal cuticle, providing a framework for addressing the evolutionary origins of the algal cuticle biosynthesis and raise important questions regarding its role, particularly across the life cycle marked by major structural ECM modifications.

biochemistry↗

bioRxiv2023

Evolutionarily conserved ovarian fluid proteins are responsible for extending egg viability in salmonid fish

In contrast to most fish species, salmonids exhibit the unique ability to hold their eggs for several days after ovulation without significant loss of viability. During this period, eggs are held in the body cavity in a biological fluid, the coelomic fluid (CF) that is responsible for preserving egg viability. To identify CF proteins responsible for preserving egg viability, a proteomic comparison was performed using 3 salmonid species and 3 non-salmonid species to identify salmonid-specific highly abundant proteins. In parallel, rainbow trout CF fractions were purified and used in a biological test to estimate their egg viability preservation potential. The most biologically active CF fractions were then subjected to mass spectrometry analysis. We identified 50 CF proteins that are overabundant in a salmonid-specific manner and present in analytical fractions exhibiting the highest egg viability preservation potential. Here we show that salmonid CF is a complex biological fluid and that several proteins are responsible for preserving egg viability. Among these key players are proteins related to immunity, calcium binding, lipid metabolism, proteolysis, extracellular matrix and sialic acid metabolic pathway.

evolutionary biology↗

bioRxiv2023

Genomic disruption of type II vitellogenin leads to vitellin membrane deficiencies andsignificant mortalities at early stages of embryonic development in zebrafish (Danio rerio)

Type II vitellogenin (Vtg2), the second most abundant type of vitellogenin in zebrafish eggs, is a major source of nutrients for early embryonic development. The main objective of this study was to determine the specific functions and essentiality of vtg2 in zebrafish early development using CRISPR/Cas9 genome editing tool. A 2811 bp deletion on gDNA was detected in vtg2-mutant zebrafish via PCR genotyping and sequencing. Introduced mutation caused vitelline membrane deficiencies and significant mortalities of mutant offspring. Further effects on female fecundity, egg fertilization rate and vtg2 gene expression and Vtgs abundance in liver were observed in F2, while effects on embryo hatching, survival rates, proteomic profiles and abundances were observed in F3 generations of the vtg2-mutant line. No change in vtg2 transcript has been detected, however, Vtg2 abundance in F2 female liver was 5x, and in 1 hpf F3 vtg2-mutant embryos was 3.8x less than Wt (p < 0.05). All Vtgs, except Vtg7, declined in abundance in 1 hpf F3 vtg2-mutant embryos (p < 0.05). Fecundity was unaffected while fertilization rate was more than halved in F2 vtg2-mutant females (p < 0.05). Hatching rate was significantly higher in F3 vtg2-mutant embryos in comparison to Wt embryos. Survival rate declined drastically to 29 % and 18 % at 24 hpf and 20 dpf, respectively, in F3 vtg2-mutant embryos. Pericardial, yolk sac/abdominal edema and spinal lordosis were evident at later stages in the surviving F3 vtg2-mutant larvae. Overrepresentation and high expression of histones, zona pellucida proteins, lectins, and protein degradation related proteins in F3 vtg2-mutant embryos provide evidence to impaired mechanisms involved in vitellin membrane formation. Findings of this study imply a potential function of Vtg2 in acquisition of vitellin membrane integrity, among other reproductive functions, and therefore, its essentiality in early zebrafish embryo development. AUTHOR SUMMARYVitellogenins (Vtgs) are major yolk nutrient precursors supporting early vertebrate development. Most species have multiple forms of Vtg, but little is known about their individual roles in reproduction and it is uncertain which forms are essential for successful development or at what stage(s) of development they are required. This study employed a CRISPR/Cas9 gene knock out (KO) to assess essentiality and functionality of Vtg2 in zebrafish, in continuation to a previously published work on type I and type III vtgs KO. The findings of this study, in combination with the previous findings, present a new model of Vtg functionality. Accordingly, Vtg2 contribute to regulation of fecundity and fertilization in female reproduction while make essential contributions to embryonic morphogenesis, hatching and embryonic and larval kinetics and survival. In addition, Vtg2 is critically important to proper formation of the vitellin membrane, and thus, to embryogenesis and later development. Our novel findings provide, for the first time, empirical evidence that the Vtg2 are essential, having critical requisite functions during oogenesis and embryonic and larval development. The overall results substantiate the concept that each type of Vtg is specialized to play unique roles in reproduction and development.

molecular biology↗

bioRxiv2020

Serine 165 Phosphorylation of SHARPIN regulates the Activation of NF-κB

The adaptor SHARPIN composes, together with the E3 ligases HOIP and HOIL1, the linear ubiquitin chain assembly complex. This enzymatic complex catalyzes and stamps atypical linear ubiquitin chains onto substrates to modify their fate, and has been linked to the regulation of the NF-κB pathway downstream most immunoreceptors, inflammation and cell death. However, how this signaling complex is regulated is not fully understood. Here, we report that a portion of SHARPIN is constitutively phosphorylated on the serine in position 165 in lymphoblastoid cells, and can be further induced following antigen receptor stimulation. Analysis of a phosphorylation-resistant mutant of SHARPIN revealed that this mark is dispensable for the generation of linear ubiquitin chains. However, phosphorylation allows the optimal activation of NF-κB in response to TNFα and T-cell receptor engagement. These results identify a new layer of regulation of the LUBAC, and unveil new strategies to modulate its action.View Full Text

immunology↗

bioRxiv2018

Genome editing reveals reproductive and developmental dependencies on specific types of vitellogenin in zebrafish (Danio rerio)

Oviparous vertebrates produce multiple forms of vitellogenin (Vtg), the major source of yolk nutrients, but little is known about their individual contributions to reproduction and development. This study employed a CRISPR/Cas9 genome editing to assess essentiality and functionality of zebrafish (Danio rerio) type-I and -III Vtgs. The multiple CRISPR approach employed to knock out (KO) all genes encoding type-I vtgs (vtg1, 4, 5, 6, and 7) simultaneously (vtg1-KO), and the type-III vtg (vtg3) individually (vtg3-KO). Results of PCR genotyping and sequencing, qPCR, LC-MS/MS and Western blotting showed that only vtg6 and vtg7 escaped Cas9 editing. In fish whose remaining type-I vtgs were incapacitated (vtg1-KO), and in vtg3-KO fish, significant increases in Vtg7 transcript and protein levels occurred in liver and eggs, a heretofore-unknown mechanism of genetic compensation to regulate Vtg homeostasis. Fecundity was more than doubled in vtg1-KO females, and fertility was ~halved in vtg3-KO females. Substantial mortality was evident in vtg3-KO eggs/embryos after only 8 h of incubation and in vtg1-KO embryos after 5 d. Hatching rate and timing were markedly impaired in vtg mutant embryos and pericardial and yolk sac/abdominal edema and spinal lordosis were evident in the larvae, with feeding and motor activities also being absent in vtg1-KO larvae. By late larval stages, vtg mutations were either completely lethal (vtg1-KO) or nearly so (vtg3-KO). These novel findings offer the first experimental evidence that different types of vertebrate Vtg are essential and have disparate requisite functions at different times during both reproduction and development.

molecular biology↗