Cell-free transfer of sterols from dictyosome-like structures to plasma membrane vesicles of guinea pig testes

Waits, Lisette P.; Dunkle, S. R.; Wilkinson, Francis E.; Moreau, Patrick; Safranski, Keri; Reust, T.; Morré, Dorothy M.; Morré, D. James

doi:10.1007/bf01349530

Cited by 5 publications

(2 citation statements)

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“…Metabolic labeling prior to cell fractionation is carried out in situ with tissues or tissue slices (e.g., amino acids for total proteins or acetate for lipids) (Nowack et al 1987;. Labeling of fractions post-isolation with [ 3 H]cholesterol or [ 3 H]inositol by exchange has been employed to examine transfer of sterols (Waits et al 1990) or inositol lipids (Harryson et al 1996). The choline head group of phosphatidylcholine has been enzymatically labeled with [ 14 C]CDPcholine as a marker for phospholipid transfer experiments .…”

Section: Introductionmentioning

confidence: 99%

Cell-free analysis of Golgi apparatus membrane traffic in rat liver

Dj¹

1998

Histochemistry and Cell Biology

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Cell-free systems for the analysis of Golgi apparatus membrane traffic rely either on highly purified cell fractions or analysis by specific trafficking markers or both. Our work has employed a cell-free transfer system from rat liver based on purified fractions. Transfer of any constituent present in the donor fraction that can be labeled (protein, phospholipid, neutral lipid, sterol, or glycoconjugate) may be investigated in a manner not requiring a processing assay. Transition vesicles were purified and Golgi apparatus cisternae were subfractionated by means of preparative free-flow electrophoresis. Using these transition vesicles and Golgi apparatus subfractions, transfer between transitional endoplasmic reticulum and cis Golgi apparatus was investigated and the process subdivided into vesicle formation and vesicle fusion steps. In liver, vesicle formation exhibited both ATP-independent and ATP-dependent components whereas vesicle fusion was ATP-independent. The ATP-dependent component of transfer was donor and acceptor specific and appeared to be largely unidirectional, i.e., ATP-dependent retrograde (cis Golgi apparatus to transitional endoplasmic reticulum) traffic was not observed. ATP-dependent transfer in the liver system and coatomer-driven ATP-independent transfer in more refined yeast and cultured cell systems are compared and discussed in regard to the liver system. A model mechanism developed for ATP-dependent budding is proposed where a retinol-stimulated and brefeldin A-inhibited NADH protein disulfide oxidoreductase (NADH oxidase) with protein disulfide-thiol interchange activity and an ATP-requiring protein capable of driving physical membrane displacement are involved. It has been suggested that this mechanism drives both the cell enlargement and the vesicle budding that may be associated with the dynamic flow of membranes along the endoplasmic reticulum-vesicle-Golgi apparatus-plasma membrane pathway.

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Section: Introductionmentioning

confidence: 99%

Cell-free analysis of Golgi apparatus membrane traffic in rat liver

Dj¹

1998

Histochemistry and Cell Biology

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“…Apocrine secretion is involved in epididymosomes to transfer various molecules toward spermatozoa in the epididymis of various animals including the turtle (Chen et al, 2016). A membrane-bound stacked cisternae from the conventional Golgi apparatus known dictyosomes is suggested for carrying the synthetic biomolecules (lipids and proteins) and delivering them to their relevant targets (Waits et al, 1990). In spermathecae of Hormogaster elisae, it was hypothesized that embedded spermatozoa in an electron-dense substance were nourished via different types of secretions such as holocrine, merocrine, and apocrine (Novo et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

Interaction of Epididymal Epithelia and their Secretions with Spermatozoa Supports Functional and Morphological Changes During Long-Term Storage in the Chinese Soft-Shelled Turtle (Pelodiscus sinensis)

et al. 2020

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Post-testicular maturation of spermatozoa is crucial for attaining the morphological and functional capabilities needed for successful fertilization. Epididymal epithelia offer a favorable environment for spermatozoa that are stored long term in the turtle epididymis; however, sperm–epithelial interactions during storage, which are enormously important for sperm functional and morphological maturation, are still largely unknown in turtles. The present study examined the epididymis during the sperm-storage period (November–April) in the Chinese soft-shelled turtle (Pelodiscus sinensis). Light and transmission electron microscopy were used to determine the cellular features of each epididymal segment (caput, corpus, and cauda) and their epithelial interactions with the spermatozoa. Spermatozoa were mainly located in the lumena of caput, corpus, and cauda epididymides. Numerous spermatozoa were bound to apical surfaces of the epithelia, and several were even embedded in the epithelial cytoplasm of the caput and corpus epididymides. No embedded spermatozoa were found in the cauda epididymis. In all epididymal segments, principal and clear cells showed the synthetic activity, evidenced by a well-developed endoplasmic reticulum network and high and low electron-dense secretory materials, respectively. Principal and clear cells in the caput and corpus segments showed embedded spermatozoa in electron-dense secretions and in the lipid droplets within the cytoplasm. No lysosomes were observed around the embedded spermatozoa. The lumena of the caput and corpus segments showed few apocrine and low electron density secretions. In the lumen of the cauda epididymidis, different secretions, such as holocrine with low and high electron density and their fragmentation, apocrine, and dictyosome, were found and are summarized. Altogether, sperm physical interactions with secretions either in the cytoplasm of epithelium or in the lumen may support the viability, morphological maintenance, and transfer of various proteins involved in long-term sperm storage in the turtle. This interaction could help us to understand the mechanisms of long-term sperm storage and provide more insights into the reproductive strategies of turtle sperm preservation.

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