Glycobiology of reproductive processes in marine animals: the state of the art

Abstract

Glycobiology is the study of complex carbohydrates in biological systems and represents a developing field of science that has made huge advances in the last half century. In fact, it combines all branches of biomedical research, revealing the vast and diverse forms of carbohydrate structures that exist in nature. Advances in structure determination have enabled scientists to study the function of complex carbohydrates in more depth and to determine the role that they play in a wide range of biological processes. Glycobiology research in marine systems has primarily focused on reproduction, in particular for what concern the chemical communication between the gametes. The current status of marine glycobiology is primarily descriptive, devoted to characterizing marine glycoconjugates with potential biomedical and biotechnological applications. In this review, we describe the current status of the glycobiology in the reproductive processes from gametogenesis to fertilization and embryo development of marine animals.

Figure 1

Immunolocalization of shrimp ovarian peritrophin (SOP) in the shrimp ovarian sections at different stages of oocyte development. Immunofluorescence labeled previtellogenic (A) and vitellogenic oocytes (B) localized at the periphery of ovarian lobe. Higher magnification revealed that SOP was specifically present in the oocyte cytoplasm from vitellogenic (C) and late vitellogenic (D) ovarian stages; no label was detected in the nucleus or in the surrounding follicular cells. In vitellogenic oocytes, SOP immunoreactivity was also detected in CRs (D) (Modified from [35]).

Figure 2

Effects of glycoprotein processing inhibitors. Eggs were fertilized and embryos cultured until 72 h post fertilization, when they were treated with (A) 4 mM 1-deoxynojirimycin (1-DNJ, which blocks both glucosidase I and II; (B) 2 mM 1-deoxymannojirimycin (1-MMN, which blocks mannosidase I); (C) untreated controls. The samples were fixed in 2% glutaraldeyde. Scale bar, 5 μm. (Modified from [217]).

Figure 3

Detection of NBD-M5 in early development with a confocal microscope. To observe the localization of NBD-M5 in living embryos, fertilized eggs pre-labeled with NBD-M5 were grown in artificial sea water without dye. At the end of mitosis (first cell division), the thick ECM (hyaline layer) near the cleavage furrow was stained (A); similar tick layers of staining were observed in 2- (B), 4- (C), 8-cell stage (D) and blastula before hatching (E and F). (F) is an higher magnification of the cortical region of (E). The localization of NBD-M5 did not change. Scale bar, 10 μm. (Modified from [62]).