Burden, Sierra, Friday G, DevBio, Lab Report

Burden, Sierra, Friday G, DevBio, Lab Report - [Acid...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
[Acid seawater effectively de-jellied Strongylocentrotus purpuratus eggs, and caused polyspermy during first cleavage and blastulation ] [Sierra Burden] [ De-jellied Strongylocentrotus purpuratus eggs were prepared by three different methods to determine which technique most effectively removed the jelly coats. The methods used were acid, soaking, and mechanical swirling. The de-jellied egg samples, along with a control, were analyzed using light microscopy for abnormalities in the first cleavage and blastulation stage. The abnormalities indicated the presence of polyspermy. For all the samples, the eggs with polyspermy were most discernible in the blastulation stage than the first cleavage stage. The results for each sample, therefore, have more eggs with polyspermy in the blastulation stage than first cleavage. The de-jellied eggs sample prepared by the acid seawater technique had the most eggs with abnormalities in the blastulation stage. As a result, the acid method most effectively removed the eggs' jelly coat and allowed for the most polyspermy. The control as expected contained no abnormalities in either stage. ] Introduction The Strogylocentrotus purpuratus eggs have a thick outer coatings consisting of glycoprotiens and polysacchirides. 1 When sperm contact the jelly coat, the components in the outer layer trigger the acrosomal reaction. The acrosomal reaction results in the release of proteolytic enzymes, which allows the sperm to penetrate the egg. For normal development, only one sperm should penetrate the egg, otherwise polyspermy arises. 2 In addition, acid de-jellied eggs have been shown to increase fertilization. Adding soluble egg jelly coat components to the acid de-jellied eggs caused decreased fertilization. 3 The egg components prevented more than one sperm from penetrating a single egg. In this experiment, de-jellied eggs were prepared by three different methods: soaking, acid, and mechanical. The soaking technique involved the eggs and sperm being placed in the cold room for several hours, while the other method consisted of adding acidic seawater to sperm and egg. To prepare eggs by mechanical swirling, eggs were hand centrifuged and re-suspended in natural seawater. The amount of polyspermy was observed in de-jellied fertilized eggs to determine which was the most effective in removing the
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/19/2011 for the course BIOLOGY 44Y taught by Professor Smith during the Winter '11 term at Stanford.

Page1 / 4

Burden, Sierra, Friday G, DevBio, Lab Report - [Acid...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online