Identification of yolk platelet-associated hydrolases in the oocytes ofRhodnius prolixus

1992 ◽  
Vol 21 (4) ◽  
pp. 253-262 ◽  
Author(s):  
Roberto H. Nussenzveig ◽  
Pedro L. Oliveira ◽  
Hatisaburo Masuda
Keyword(s):  
Yolk Platelet

The utilization of yolk platelets by tissues of Xenopus embryos studied by a safranin staining method

Development ◽  
1965 ◽  
Vol 14 (2) ◽  
pp. 191-212
Author(s):  
G. G. Selman ◽  
G. J. Pawsey
Keyword(s):  
Electron Microscopy ◽  
Amino Acid ◽  
Chemical Analysis ◽  
Amino Acid Composition ◽  
Rana Pipiens ◽  
Staining Method ◽  
Peripheral Zone ◽  
Main Body ◽  
Yolk Platelet ◽  
Similar Amino Acid

The amphibian yolk platelet is a particular kind of food-reserve granule which may be easily recognized by microscopy and which is abundant in the cytoplasm of amphibian eggs and embryos. Wallace & Karasaki (1963) developed a method by which intact yolk platelets were isolated from eggs of Rana pipiens and were shown by electron microscopy to be practically free from other materials. Chemical analysis of such yolk platelets by Wallace (1963a, b) showed that the crystalline main body is made up of two components, a phosphoprotein of similar amino-acid composition to avian phosvitin and a lipoprotein similar to avian α-lipovitellin, the molecular proportions being 2 to 1 respectively. Surrounding this crystalline main body of the yolk platelet there is a granular peripheral zone which has been reported to contain both protein resembling histone (Horn, 1962) and polysaccharide (Ohno, Karasaki & Takata, 1964).

Recent findings in oogenesis of Drosophila melanogaster

Development ◽  
1977 ◽  
Vol 39 (1) ◽  
pp. 45-57
Author(s):  
F. Giorgi ◽  
J. Jacob
Keyword(s):  
Drosophila Melanogaster ◽  
Acid Phosphatase ◽  
Ovarian Development ◽  
Superficial Layer ◽  
Blood Proteins ◽  
Selective Hydrolysis ◽  
Internal Lining ◽  
Hydrolysis Of ◽  
Zinc Iodide ◽  
Yolk Platelet

The role played by the vitellogenic oocytes of Drosophila melanogaster in relation to the elaboration of material taken from the haemolymph is examined by ultrastructural cytochemistry. As revealed by the Gomori procedure, acid phosphatase occurs widely over the forming yolk platelets of the cortical and central ooplasm. A number of Golgi apparatuses in thecortical ooplasm are also positively stained with lead precipitates. With the proceeding of the ovarian development it becomes progressively more difficult to demonstrate cytochemically the enzyme over the yolk platelets. In stage 9–10 chambers the acid phosphatase is restricted to the so-called associated body, while the rest of the yolk platelet appears devoid of lead deposits. By using a osmium zinc iodide (OZ1) complex as a preferential staining method for the Golgi apparatus, it has been shown that, apart from the apparatus itself, a number of OZI deposits occur over the superficial layer of the forming yolk platelets. When mature yolk platelets are formed at later stages, the OZI deposits in the yolk platelets come to be restricted to the cap-like region of the superficial layer which contains the associated body. In vitellogenic oocytes, both the internal lining of the limiting membrane of the forming yolk platelets and the associated body of the mature yolk platelets react positively, to cytochemical methods to demonstrate carbohydrates. The present findings are interpreted as indicating the involvement of lysosomal enzymes in the process of maturation of the yolk material. The suggestion is also made that such an involvement is required to accomplish a selective hydrolysis of those blood proteins which have been taken in by vitellogenic oocytes along with yolk precursors.

Yolk platelet degradation in preemergence Artemia embryos: response to protons in vivo and in vitro

1987 ◽  
Vol 252 (4) ◽  
pp. R774-R781 ◽  
Author(s):  
P. J. Utterback ◽  
S. C. Hand
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dry Weight ◽  
Platelet Protein ◽  
Transmission Electron ◽  
Structural Differences ◽  
Alkaline Conditions ◽  
Yolk Platelet

Alteration of intracellular pH (pHi) influences yolk platelet degradation during preemergence development in Artemia embryos. Cysts incubated for 10 h under conditions of aerobic development (aqueous medium equilibrated with 60% N2-40% O2, pHi greater than or equal to 7.9) exhibit a significant decrease in numbers of yolk platelets and platelet protein. In contrast, cysts incubated for 10 h under aerobic acidosis (60% CO2-40% O2, pHi = 6.8) show no significant decrease in numbers of yolk platelets or platelet protein. When subjected to alkaline conditions in vitro, yolk platelets release protein exponentially as a function of time. The process is essentially complete in 40 min. The extent of protein and lipid release from platelets increases markedly as pH of the medium is raised in increments from 6.3 to 8.0. Concomitant with these changes are reduction (50%) in platelet dry weight and reduction (21%) in platelet diameter. Transmission electron microscopy does not reveal major structural differences between isolated yolk platelets and those contained in hydrated embryos. The proton effects on platelet composition and size detected in vitro may explain in part the mechanism of platelet degradation observed during aerobic development and its suppression under conditions of acidic pHi.

Yolk-platelet crystals in three ancient bony fishes: Polypterus bichir (polypteri), Amia calva L., and Lepisosteus osseus (L.) (Holostei)

1982 ◽  
Vol 222 (1) ◽  
pp. 159-165 ◽  
Author(s):  
Rainer H. Lange ◽  
Zygmunt Grodziński ◽  
Wincenty Kilarski
Keyword(s):  
Bony Fishes ◽  
Amia Calva ◽  
Yolk Platelet

Lipoprotein assembly in Xenopus yolk-platelet crystals

Nature ◽  
1982 ◽  
Vol 295 (5846) ◽  
pp. 264-264 ◽  
Author(s):  
LEONARD J. BANASZAK ◽  
DOUGLAS H. OHLENDORF
Keyword(s):  
Lipoprotein Assembly ◽  
Yolk Platelet

scholarly journals The crystalline yolk-platelet proteins and their soluble plasma precursor in an amphibian, Xenopus laevis

1971 ◽  
Vol 124 (4) ◽  
pp. 759-766 ◽  
Author(s):  
M. R. Redshaw ◽  
B. K. Follett
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Xenopus Laevis ◽  
Amino Acid Composition ◽  
High Molecular Weight ◽  
Molecular Rearrangement ◽  
Yolk Proteins ◽  
Platelet Protein ◽  
Yolk Platelet ◽  
Preparative Ultracentrifugation

A single lipophosphoprotein complex, vitellogenin, was isolated and purified from the plasma of oestrogen-stimulated female toads by preparative ultracentrifugation and chromatography on TEAE-cellulose (triethylaminoethylcellulose). The protein contains 12% lipid, 1.5% phosphorus, 1.6% calcium and smaller amounts of carbohydrates and biliverdin. In amino acid composition it is identical with total yolk-platelet protein. The platelet protein, however, is fractionated on TEAE-cellulose into two components, a high-molecular-weight lipovitellin and a smaller phosvitin. Analyses of the soluble plasma vitellogenin suggest that it is a complex of two phosvitin molecules covalently bound to one lipovitellin dimer, and that it is the immediate precursor of the yolk proteins, into which it is converted by a molecular rearrangement. Uptake of vitellogenin from the plasma into the growing oocyte, and its subsequent crystallization as a yolk platelet, appear to be enhanced by gonadotrophic hormones.

Oogenesis and ovarian development cycle of the spiny lobster Panulirus japonicus (Decapoda:Palinuridae)

1997 ◽  
Vol 48 (8) ◽  
pp. 875 ◽  
Author(s):  
Megumi Minagawa ◽  
Motohiko Sano
Keyword(s):  
Ovarian Development ◽  
Gonadosomatic Index ◽  
Spiny Lobster ◽  
Light And Electron Microscopy ◽  
Morphological Characteristics ◽  
Dense Granules ◽  
Development Cycle ◽  
Maturation Stages ◽  
Panulirus Japonicus ◽  
Yolk Platelet

Oogenesis and ovarian development in female Panulirus japonicus were examined by light and electron microscopy. Eight substages (oogonium, bouquet, chromatin nucleolus, oil globule, pre-yolk platelet, yolk platelet, pre-maturation and maturation) were distinguished in the typical process of oogenesis (multiplication, pre-vitellogenesis, vitellogenesis and maturation stages). Yolk accumulation started at the late pre-yolk platelet substage, when electron-dense granules appeared. Yolk granules seemed to be accumulated in two ways, being produced endogenously by the abundant rough endoplasmic reticulum during vitellogenesis and exogenously by micropinocytosis from the yolk platelet to pre-maturation substages. Ovulation occurred after oocytes became mature (i.e. after the metaphase of the primary maturation division was reached). The diameter of mature oocytes was 465–477 µm. The seasonal ovarian development cycle was divided into seven stages: inactive, developing, ripe, re- developing, re-ripe, spawned and recovery. The morphological characteristics relating to the gonadosomatic index (GSI) of each stage are described (GSI was calculated by the formula I = W × 105/L3, where I represents GSI, W is the gonad weight in grams, and L is the carapace length in millimetres). Estimated GSI values ranged from 11.3 to 12.4 in individuals with mature oocytes, and the 99% confidence intervals for GSI values of adjacent oogenesis substages did not overlap. GSI values at the developing and ripe stages were significantly larger than those at the re-developing and re-ripe stages, respectively.

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