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Growing Oocyte (growing + oocyte)

Distribution by Scientific Domains
Life Sciences60%

Selected Abstracts

Programmed cell death of the ovarian nurse cells during oogenesis of the silkmoth Bombyx mori

DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 7 2006
Vicky E. Mpakou
In the present study, we describe the features of programmed cell death of the ovarian nurse cells occurring during vitellogenesis of the silkmoth Bombyx mori. At developmental stage 5, the nurse cells occupy one-half of the follicular volume and obtain a rather spherical shape, while the nurse cell nuclei appear large and elongated, forming impressive projections. At the following stage, stage 6, the nurse cells decrease in size and their shape becomes elliptic. The nuclei remain elongated, being also characterized by large lobes. The lobes of the ramified nurse cell nuclei seem to retain the nucleus in the center of the cell during the dumping of the nurse cell cytoplasm into the growing oocyte. At stage 7, membrane enclosed vacuoles can be easily detected into the nurse cells cytoplasm. Ultrastructural analysis and fluorescent microscopy using mono-dansyl-cadaverine staining of these vacuoles also reveal that they represent autolysosomes. Caspase activity is detected during stage 7, as it is demonstrated by using the Red-VAD-FMK staining reagent. At developmental stages 8 and 9, the nurse cells exhibit chromatin condensation, DNA fragmentation and caspase activity. Finally, during the following stage 10, the nuclear remnants are assembled into apoptotic vesicles, which, after being phagocytosed, are observed in the cytoplasm of adjacent follicle cells. We propose that apoptosis and autophagy operate synergistically during vitellogenesis of B. mori, in order to achieve an efficient and rapid clearance of the degenerated nurse cell cluster. [source]

Postendocytic Provitellin Processing in the Growing Oocyte of the Short Horned Grasshopper, Oxyajaponicajaponica (Orthoptera: Acrididae)

ENTOMOLOGICAL RESEARCH, Issue 1 2004
Sae Youll CHO
ABSTRACT Polyclonal antibodies made against 86 kDa (86 k), 80 kDa (80 k) and 54 kDa (54 k) vitellins of Oxya japonica japonica are used for Western blotting. Anti-80k vitellin antibody is cross-reacted with a 95 kDa (95 k) vitellin. While 95 k vitellin is present both in the female hemolymph and in the oocyte, 80 k vitellin is detected only in the oocyte and the laid egg. In the growing oocytes, as 95 k vitellin is faded out gradually, 80 k vitellin is accumulated increasingly, indicating postendocytic processing of 95 k vitellin brings 80 k vitellin. Further conforming the hypothesis, partial digestion of 95 k vitellin with pepsin and ,-chymotrypsin makes several protein bands of molecular weight around 80 kDa. Thus, the 95k vitellin may have a cleavage site (s) to produce 80 k vitellin which forms fairly stable tertiary structure. In the reduced condition (20 mM glutathion), both 95 k and 80 k vitellins were digested throughly by endogenous proteinase at pH 4. Both 86 k and 54 k vitellins, respectively, show no apparent molecular weight changes in the growing oocyte and in the hemolymph. [source]

Requirement for amino acids in ontogeny of fish

AQUACULTURE RESEARCH, Issue 5 2010
Roderick Nigel Finn
Abstract Amino acids are vital for all living organisms. During early fish ontogeny, they are important fuel molecules, signalling factors and major substrates for the synthesis of a wide range of bioactive molecules and proteins. Because the majority of fish eggs are cleidoic, i.e. closed free-living systems following ovulation and activation, early development of fish depends on the maternal provision of amino acids during oogenesis. While more than 600 proteins have been identified in the growing oocytes of fish, the major vehicles for supplying amino acids to the growing oocyte before ovulation are the vitellogenins, of which many genes and multiple forms are known. Here we review the importance of amino acids for the intermediary metabolism of fish embryos and larvae, where amino acids have been shown to be the preferred catabolic substrate. Subsequently, we address the specialization of the lysosomal pathway involved in the uptake and degradation of yolk proteins. This latter pathway is specifically modified in the germline to facilitate the long-term storage of egg yolk proteins. In marine teleosts, the degradative pathway may be activated before fertilization during oocyte maturation to release free amino acids for oocyte hydration and the acquisition of egg buoyancy. In other species, including freshwater fish, a more latent activation of acid hydrolases occurs after fertilization during the four phases of yolk resorption. The developmental contributions of the yolk syncytial layer, vitelline circulation and liver are essential components of the amino acid supply during fish ontogeny. [source]

Postendocytic Provitellin Processing in the Growing Oocyte of the Short Horned Grasshopper, Oxyajaponicajaponica (Orthoptera: Acrididae)

ENTOMOLOGICAL RESEARCH, Issue 1 2004
Sae Youll CHO
ABSTRACT Polyclonal antibodies made against 86 kDa (86 k), 80 kDa (80 k) and 54 kDa (54 k) vitellins of Oxya japonica japonica are used for Western blotting. Anti-80k vitellin antibody is cross-reacted with a 95 kDa (95 k) vitellin. While 95 k vitellin is present both in the female hemolymph and in the oocyte, 80 k vitellin is detected only in the oocyte and the laid egg. In the growing oocytes, as 95 k vitellin is faded out gradually, 80 k vitellin is accumulated increasingly, indicating postendocytic processing of 95 k vitellin brings 80 k vitellin. Further conforming the hypothesis, partial digestion of 95 k vitellin with pepsin and ,-chymotrypsin makes several protein bands of molecular weight around 80 kDa. Thus, the 95k vitellin may have a cleavage site (s) to produce 80 k vitellin which forms fairly stable tertiary structure. In the reduced condition (20 mM glutathion), both 95 k and 80 k vitellins were digested throughly by endogenous proteinase at pH 4. Both 86 k and 54 k vitellins, respectively, show no apparent molecular weight changes in the growing oocyte and in the hemolymph. [source]

Requirement for amino acids in ontogeny of fish

AQUACULTURE RESEARCH, Issue 5 2010
Roderick Nigel Finn
Abstract Amino acids are vital for all living organisms. During early fish ontogeny, they are important fuel molecules, signalling factors and major substrates for the synthesis of a wide range of bioactive molecules and proteins. Because the majority of fish eggs are cleidoic, i.e. closed free-living systems following ovulation and activation, early development of fish depends on the maternal provision of amino acids during oogenesis. While more than 600 proteins have been identified in the growing oocytes of fish, the major vehicles for supplying amino acids to the growing oocyte before ovulation are the vitellogenins, of which many genes and multiple forms are known. Here we review the importance of amino acids for the intermediary metabolism of fish embryos and larvae, where amino acids have been shown to be the preferred catabolic substrate. Subsequently, we address the specialization of the lysosomal pathway involved in the uptake and degradation of yolk proteins. This latter pathway is specifically modified in the germline to facilitate the long-term storage of egg yolk proteins. In marine teleosts, the degradative pathway may be activated before fertilization during oocyte maturation to release free amino acids for oocyte hydration and the acquisition of egg buoyancy. In other species, including freshwater fish, a more latent activation of acid hydrolases occurs after fertilization during the four phases of yolk resorption. The developmental contributions of the yolk syncytial layer, vitelline circulation and liver are essential components of the amino acid supply during fish ontogeny. [source]