Chapter 34, Problem 4Q

Summary Introduction

To analyze:

Whether the plasma intrinsic proteins (PIPs) will be most prominent in a symplastic pathway or apoplastic pathway, when the roots are stained particularly for the PIPs.

Given:

The oocytes of the frog Xenopus laevis were taken by the researchers and injected with the mRNA (messenger ribonucleic acid) of plant TIP (tonoplast intrinsic protein). The oocytes of the frog are known to have a larger size and a low osmotic cell permeability. The mRNA of a nontransport protein is also taken by the researchers and injected into the oocytes. Some of the oocytes were kept uninjected. The cells from these three cases were observed after incubating them for 2 days in isotonic medium and then they were given treatment with a hypotonic solution.

The graph showing the changes in relative volume on the y-axis and time (in minutes) on the x-axis was plotted as shown below:

It was also observed that the oocytes, which had TIP mRNA burst after sometime while the oocytes which were injected with a different nontransport protein and the oocytes, which were kept uninjected do not burst. The following table depicts the osmotic water permeability of the three conditions as calculated by the researchers.

Introduction:

Aquaporins are the integral membrane proteins, which are responsible for the transport of molecules of lower weight across the bilipid layer. They are of four types, that is, PIPs, TIPs, NOD-like intrinsic proteins, and small basic intrinsic proteins. PIPs are the plasma proteins, which are usually found in roots and help in the transportation of water and minerals from the roots to the other parts of the plants.