Melike Erkan

Fine structural study of the spermatogenic cycle in Pitar rudis and Chamelea gallina (Mollusca, Bivalvia, Veneridae).

A comparative ultrastructural study of spermatogenesis was performed in the bivalve molluscs Pitar rudis and Chamelea gallina (Veneridae) from Turkey. Sertoli cells appeared to be rich in glycogen, lipid droplets and germ-cell phagolysosomes. Premeiotic cells exhibited nuage and a flagellum, with the Golgi complex and the rough endoplasmic reticulum originating proacrosomal vesicles during the pachytene stage. In round spermatids, the acrosomal vesicle migrated linked to the plasma membrane. In P. rudis, the acrosomal vesicle base formed a thin expansion that attached to the nuclear apex and was associated with development of the perforatorium. The cap-shaped acrosomal vesicle then differentiated into external and internal regions, and also into a small apical light region, although some cells exhibited an apical extension of the external component. On the contrary, two lateroapical light pouches developed in C. gallina. During spermiogenesis, chromatin became fibrillar and then condensed while the nucleus turned conical shaped in P. rudis or slightly curved in C. gallina. In P. rudis, the midpiece contained glycogen and four mitochondria, although five mitochondria were sometimes observed, whereas in C. gallina the midpiece contained four mitochondria. Comparison with other members of Veneroida shows a common ectaquasperm type, but novel findings in acrosome biogenesis.

Male Reproductive System Morphology and Spermatophore Formation in Astacus Leptodactylus (Eschscholtz, 1823) (Decapoda: Astacidae)

Abstract We studied the morphology of the male reproductive system and spermatophore formation in Astacus leptodactylus. The testis has two anterior lobules and only one posterior lobule, which lie dorsal to the gut on the large hepatopancreas. Collecting tubule cells comprise a simple cuboidal epithelium with synthetic activity. Vasa deferentia are laterally connected with the testis and have three parts: proximal vas deferens (PVD), middle vas deferens (MVD) and distal vas deferens (DVD). While the PVD is off-white in color similar to the testis and has no convolutions, the MVD is intensely white in color and convoluted. On the other hand, the DVD is the widest of all and an intensely white structure. The spermatophore, which is non-pedunculate and tubular, extrudes an uninterrupted column and consists of a sperm mass covered with primary and secondary layers. The primary layer is stained with bromephenol blue, while secondary layer gives positive reaction with Alcian blue and aldehyde fuchsin. The histochemical results indicate that the functions of layers are different.

Morphology of Testis and vas Deferens in the Xanthoid Crab, Eriphia verrucosa (Forskål, 1775) (Decapoda: brachyura)

Abstract The anatomy of the male reproductive organs of the brachyuran crab Eriphia verrucosa is presented, with a detailed analysis of the histology and histochemistry of the regional structure of the testis and vas deferens. The H-shaped testis is subdivided into three distinct parts: anterior, intermediate and posterior. The vas deferens is continuous with the posterior part of the testis, ends at the gonopore, and is subdivided into three distinct regions: proximal, medial and distal. The anterior part of the testis exhibits convoluted lobules including seminiferous tubules. Whereas the intermediate part of the testis has a simple columnar epithelium, the posterior part of the testis has a simple squamous epithelium. In the proximal and medial regions of the vas deferens, there is a simple cubic epithelium, while in the distal region of the vas deferens there is a high columnar epithelium. Spermatophores are first formed in the convoluted proximal region of the vas deferens and are encapsulated by mainly protein secretions in the distal region. These results suggest that the testis and vas deferens of Eriphia show similarity to the testis and vas deferens of other brachyuran crabs except for some slight differences. During formation of the spermatophores in the vas deferens the spermatozoa are prepared for successful fertilization.

Ultrastructure of ovary and oogenesis in Chamelea gallina (Linné, 1758) (Bivalvia, Veneridae)

Abstract This is an ultrastructural study of the development of oocytes in the female venerid clam Chamalea gallina that is an economically valuable species. Specimens were collected from the Western Black Sea and the ultrastructural changes from oogonia to mature oocytes are described. The interfollicular tissue between the acini of the ovary of this species is composed of vesicular connective tissue, and a small number of follicle cells surround previtellogenic oocytes completely and move towards the stalk area at the late vitellogenic stage. Vitellogenesis may occur autosynthetically within the collaboration of Golgi complex, mitochondria and rough endoplasmic reticulum from the previtellogenic stage to the formation of mature egg. Besides autosythetic activity, intense endocytotic activity contributes to vitellogenesis heterosynthetically from the late vitellogenic stage to the end of yolk deposition. Despite high nuclear blebbing activity that is assumed to be performed to provide thenecessary membrane for vesicule formation, oogenesis in C. gallina is similar to that in many bivalve species studied so far.

The toxic effects of polychlorinated biphenyl (Aroclor 1242) on Tm3 Leydig cells

Polychlorinated biphenyls (PCBs) are ubiquitous and persistent environmental contaminants that disrupt endocrine function in biological systems, especially in the male reproductive system. Previous studies on the reproductive toxicity of PCBs have focused on the impairment of spermatogenesis, disruption of steroidogenesis, decreased sperm number, and infertility. Aroclor 1242 is a commercial mixture with an average of 42% chlorine by weight. The purpose of the present study was to elucidate the hazardous effects of Aroclor 1242 on Leydig cells through an evaluation of cell viability, lipid peroxidation, hydroxyl radicals, H2O2 production, antioxidant enzymes, and steroidogenic enzymes. Leydig cells were exposed to Aroclor 1242 for 24 h under basal and luteinizing hormone-stimulated conditions at different concentrations (ranging from 10−16 M to 10−6 M). After incubation, Leydig cells were measured for cell viability, lipid peroxidation, reactive oxygen species (hydroxyl radical and H2O2), antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase, and glutathione-S-transferase), and steroidogenic enzymes (3β-hydroxysteroid dehydrogenase [HSD] and 17β-HSD). The results showed that cell viability was reduced only at Aroclor 1242 concentrations of 10−6 M and 10−8 M, whereas lipid peroxidation and reactive oxygen species increased relative to the concentration. Furthermore, antioxidant systems and steroidogenesis were interrupted to varying degrees, relative to the concentration. These findings suggest that exposure to Aroclor 1242 at high concentrations may result in detrimental effects to Leydig cell homeostasis. In addition, Aroclor 1242 may impair steroidogenesis, especially testosterone biosynthesis, by inhibiting two important steroidogenic enzymes.

Morphological and histochemical examination of male and female gonads in Homarus gammarus (L. 1758)

The reproductive organs of both male and female European lobsters (Homarus gammarus) are H-shaped gonads that lie dorsal to the gut on the large hepatopancreas. The ovary consists of a pair of tubular, parallel lobules with a connecting bridge. The germarium of the ovary containing oogonia is concentrated in the center of the ovarian lobe. As oogonesis proceeds, the oocytes move to the peripheral regions of the ovary. The follicle cells begin to surround the oocytes in the previtellogenic stage, and the mature oocytes are completely surrounded by the follicle cells. Carbohydrates exist in both early and late vitellogenic oocytes that give PAS positive reaction. However, their rising protein content in late vitellogenic oocytes makes them stain with Bromophenol blue. Testes show convoluted lobules with a germinal epithelium and a central collecting duct, and the paired vasa deferentia have three distinct parts. Spermatophores are nonpedunculate and tubular, which extrude as a continuous column and consist of a sperm mass covered with primary and secondary layers. The primary layer stains with Bromophenol Blue and gives a PAS positive reaction. But the secondary layer only weakly stains with Bromophenol Blue. The histochemical results may indicate that the function of the two layers is different.

Acrylamide disrupts the steroidogenic pathway in Leydig cells: possible mechanism of action

ABSTRACT Acrylamide-treated Leydig cells were tested for cytotoxicity, testosterone secretion, 3′,5′-cyclic adenosine monophosphate production, and gene and protein expression of steroidogenic genes and transcription factors. Reverse-transcriptional real-time polymerase chain reaction and western blot analysis revealed that acrylamide disrupts mRNA and protein expression of steroidogenic markers, including luteinizing hormone receptor, steroidogenic acute regulatory protein, cholesterol side-chain cleavage enzyme, 3β-hydroxy dehydrogenase, and 17β-hydroxy dehydrogenase. Further, transcription levels of the key regulator transcription factors, steroidogenic factor-1, GATA binding protein-4, and nerve growth factor IB, were evaluated. Acrylamide induced cytotoxicity and decreased testosterone and 3′,5′-cyclic adenosine monophosphate secretion by altering the rate-limiting steps in Leydig cell steroidogenesis.

De novo assembly and comprehensive characterization of the skeletal muscle transcriptomes of the European anchovy (Engraulis encrasicolus).

European anchovy has considerable economic and ecological importance due to its high reproduction capacity and growth rate. As one of the largest source of wild marine protein, an increasing muscle mass strength has a major contribution to this growth rate during transition from subadult to adult stage. In the present study, using Illumina sequencing technology (HiSeq2000) accompanied with appropriate bioinformatics softwares; we have sequenced, assembled and annotated the transcriptome of wild subadult and adult anchovy muscles. A total of 131,081,776 high-quality reads were assembled into 125,506 contigs with an average length of 709.35 bp and N50 length of 1159 bp. Functional annotations of assembled contigs have been summarized according to 3325 GO terms, 3370 PFAM domains and 378 predicted KEGG metabolic pathways. About 11% of all contigs had at least one type of SSR motif in their sequences. According to the sequence homology analysis by BlasTN it was concluded that the assembled contigs include 16 skeletal muscle-expressed miRNAs, 14 ncRNAs and most of sarcomeric/myofibrillar genes. We hope that the sequence information regarding the muscle transcriptome of anchovy can provide some insight into the understanding of genome-wide transcriptome profile of teleost muscle tissue and give useful information in fish muscle development.

Ultrastructure of spermatogenesis in Cerastoderma glaucum (Cardiacea) and Spisula subtruncata (Mactracea)

Summary In Cerastoderma glaucum, Sertoli cells are rich in lipids, glycogen and lysosomes, and premeiotic cells exhibited nuage, a prominent Golgi complex and endoplasmic reticulum cisternae encircling the nucleus. The Golgi complex gives rise to proacrosomal vesicles during mid-spermiogenesis, and the round acrosomal vesicle, with a dense fibrillar core, migrates laterally while linked to the plasma membrane as it develops the subacrosomal material. In its final position, the vesicle becomes cap-shaped (0.6 μm) and differentiates into apical light and basal dense regions. The elongated and helicoidal nucleus (8–9.9 μm) has a thin tip (0.3 μm) that invades the subacrosomal space, and in the midpiece (0.8 μm) two of the four mitochondria extend laterally to the nucleus (1.5–2.1 μm). In Spisula subtruncata, Sertoli cells are rich in lipids, glycogen and phagocytosed sperm. Premeiotic cells exhibit nuage, a prominent Golgi complex that gives rise to proacrosomal vesicles from the leptotene stage and a flagellimi that is extruded at zygotene. The acrosomal vesicle forms during the round spermatid stage and differentiates into a large and dense basal region and an apical light region. It then migrates while linked to the plasma membrane by its apical pole. Development of the subacrosomal perforatorium is associated with nuage materials and endoplasmic reticulum vesicles. The mature cap-shaped (0.6 μm) acrosomal vesicle exhibits a large apical and irregular region with floccular contents and a basal dense region. The round nucleus becomes barrel-shaped (1.5 μm) and the midpiece (0.8 μm), with four mitochondria, contains a few glycogen particles.

Sodium arsenite-induced detriment of cell function in Leydig and Sertoli cells: the potential relation of oxidative damage and antioxidant defense system

Abstract Arsenic is commonly found in the natural environment and is toxic agent for living organism in many countries in the world. Studies on animal models suggest that exposure to arsenic may cause reproductive toxicity; however, effect of arsenic on reproductive toxicity has still not been clearly described. This study was focused on cytotoxicity, oxidative stress, and the antioxidant defense system induced with exposure to sodium arsenite in Mus musculus Leydig and Sertoli cells. The cells were exposed to two different concentrations of sodium arsenite of 50 ppb (0.4 μM) and 1000 ppb (7.7 μM) for 24, 48, and 72 h. Following the exposure time, cell viability, cell proliferation, and lactate dehydrogenase (LDH) activity were determining using colorimetric method. Also, we evaluated oxidative stress markers such as glutathione (GSH), lipid peroxidation, hydroxyl radical, hydrogen peroxide levels, and cellular enzymatic antioxidants such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione-s-transferase, and γ-glutamyl transpeptidase (γ-GT). As a result, sodium arsenite exposure in Leydig and Sertoli cells caused cellular cytotoxicity and downregulated the antioxidant defense system by inducing oxidative stress depending on concentration and time. Furthermore, this study demonstrated that when compared with Sertoli cells, Leydig cells were more affected by arsenite toxicity.