Martha Louise Schade

Bio: Martha Louise Schade is an academic researcher from University of Western Ontario. The author has contributed to research in topics: Perivitelline space & Vitellogenesis. The author has an hindex of 1, co-authored 1 publications receiving 45 citations.

Structural modulation of the surface and cytoplasm of oocytes during vitellogenesis in the lobster, Homarus americanus. An electron microscope-protein tracer study.

Abstract: The present investigation describes the ultrastructural changes which occur at the surface and in the cytoplasm of developing oocytes of the lobster, Homarus americanus, during vitellogenesis. The immature oocytes showed no surface specializations of the oolemma and no pinocytotic activity was observed. Horseradish peroxidase (HRP) tracer studies showed penetration of the tracer into the perivitelline space, but no uptake by the oocytes. The surfaces of oocytes examined during vitellogenesis, when yolk protein accumulation was maximal, exhibited numerous microvilli that projected into the perivitelline space, often appearing to be embedded in the follicular cell mass. In addition, the plasma membrane of vitellogenic oocytes contained many pinocytotic pits frequently situated at the bases of microvilli. The perivitelline space was engorged with electrondense material which appeared similar to that contained in pinocytotic structures of the oocytes. Vitellogenic oocytes incubated in HRP showed uptake of tracer reaction product by the coated pits and vesicles of the oolemma. Aggregation and subsequent fusion of these vesicles into large multivesicular bodies of ingested material were also observed in vitellogenic oocytes. Animals artificially induced to undergo vitellogenesis exhibited modulations of oocyte ultrastructure similar to those of normal vitellogenesis, notably, pinocytotic incorporation of extra-oocytic material and hypertrophy of oocyte surface microvilli. This study supports the hypothesis for a dual source of yolk protein in the American lobster.

Female reproduction in Malacostracan Crustacea.

Abstract: 1. General considerations 221 2. Origin of vitellogenin 222 3. Vitellogenin uptake by vitellogenic ovaries 223 a) Transformation and role of the follicle envelope 223 b) Vitellogenic oocyte and endocytosis mechanism 224 4. From vitellogenin to vitellin: a processing? 224 5. Vitellogenin synthesis and vitellogenin level in haemolymph as means for monitoring vitellogenesis 226 6. Timing of the reproductive cycle: duration and relation with the molting cycle 227 B. Vitellogenesis control 229 1. Inhibitory control by VIH (Vitellogenesis Inhibiting Hormone) 229 a) The X organ-sinus gland complex 229 Eyestalked species Eyestalkless species b) Ways of action 230 Control of vitellogenin synthesis Control of vitellogenin uptake by the oocytes c) Extraction and purification of VIH 231 d) Latest data on VIH 231 2. Stimulatory control 233 a) Neurohumoral factors 234 b) Vitellogenin Stimulating Ovarian Hormone (VSOH) 234 c) Ecdysteroids 234 d) Juvenoids 235 e) Ovary-stimulating factor from males 237

Vitellogenesis in the shrimp, Penaeus vannamei: in vitro studies of the isolated hepatopancreas and ovary

Abstract: 1. 1. Yolk proteins were isolated from ovaries of the shrimp Penaeus vannamei and used as an antigen for antibody production in rabbits. 2. 2. Protein synthesis was measured for both the hepatopancreas and the ovary in vitro, and proteins present in both tissues were immunoreactive with the antibodies. 3. 3. Extracts of shrimp eyestalks inhibited in vitro protein synthesis by both tissues. The inhibitory factor from the eyestalks was heat stable and had a molecular weight of 3300 daltons.

Reproductive cycle of ovarian development and vitellogenin profiles in the freshwater prawns, Macrobrachium rosenbergii

Abstract: Summary The objectives were to characterize the ovarian development and hemolymph vitellogenin concentrations during the reproductive cycle in the freshwater prawn, Macrobrachium rosenbergii. The ovaries of M. rosenbergii were classified into five developmental stages, and the ovarian histology of each stage was characterized. The ovarian stages correlated closely with the gonadosomatic index, the oocyte diameters, and the characteristics of ovarian histology. Sequential bleeding at 3-day intervals from each of seven prawns was also conducted for at least two reproductive cycles. Vitellogenin concentrations in the hemolymph were measured with a validated enzyme-linked immunosorbent assay. Vitellogenin concentrations in the hemolymph showed similar profiles in the 18 reproductive cycles tested in these prawns. Vitellogenin concentrations increased in the hemolymph of prawns in the early stages of ovarian development (stage I or 11) and were maintained at high levels until stage V. Hemolymph vitellogenin co...

Protein, vitellogenin, and vitellin levels in the hemolymph and ovaries during ovarian development in Penaeus semisulcatus (de Haan)

Abstract: The concentration of vitellogenin (Vg) in the hemolymph of Penaeus semisulcatus was found to increase from an average of 50 μg ml-1 to 439 μg ml-1 in female shrimp during ovarian development. The most significant increase in Vg occurred concomitant with the increase in the vitellin (Vt) content of oocytes with an average diameter (AOD) ranging between 150 and 250 μm. The amount of Vt in the oocytes was found to increase linearly from a mean of 0.0126 mg to 4.55 mg per gm body weight. However, the percentage of Vt in the total protein was found to decrease, from 67% in ovaries with AOD of 150-250 μm, to 39.7% in ovaries with AOD of 350 μm or larger. The volume of the hemolymph was found to be 0.4 ml per gm body weight and did not change significantly during ovarian development. Assuming that Vg in the hemolymph represents either an extraovarian origin of Vt or an active secretion from the ovary, a turnover rate of two to three times per day was calculated over one full cycle of oocyte development. However, during the most significant increase in Vt in the ovary (in ovaries with AOD of 150-250 μm), the turnover rate in the hemolymph could reach seven to eight times per day. The results lead to the conclusion that the contribution of Vg to the formation of Vt in the ovary is quantitatively insignificant.

Cell and Molecular Biology of Artemia Development

Abstract: Research reports from 25 laboratories working with the brine shrimp Artemia to investigate the patterns of development, the biochemistry and the structure and expression of genes in crustaceans. The 27 full papers and abstracts of another 17 are divided into sections on dormancy and development, cel