Sunday, October 3, 2010

Weekly Dev Bio post. LAB: Nematodes

Nematode Under 50x
Last week in lab we ended up cutting up earthworms and laying the pieces on a nutrient enriched petri dish in hopes of nematodes hatching. After 2 days the nematodes pathways were visible to the naked eye as they migrated away from the decaying worm. After 3 days there was a huge increase in pathways and very small visible worms. The 4th day there was a good mixture of large, medium, and small nematodes easily seen.


Further research: I read around many different articles and got some extra info on nematodes. They are a form of round worm that have digestive, excretory, reproductive , and nervous systems. They lack respiratory and circulatory systems. There digestive system is a tube that runs from the mouth to the anus (Fig 1.)
Fig. 1

Most nematodes are parasites to plants, animals, and insects. The parasitic nematodes find there hosts through carbon dioxide which is released from breathing or waste products. They track the carbon dioxide and enter the host either through the respiratory system or anus. When they are within there host they release a bacteria which will kill insect hosts over a few days. The bacteria will multiply and the worm will reproduce creating tons of nematodes that feed on the bacteria inside the host. They are used typically for biological control in particular areas that need a species reduced or killed off.

A article i read about the germ granule development in the nematode and how they maintain/preserve the same the germ granules over many lineages.
Bioinformatic analysis of P granule-related proteins: insights into germ granule evolution in nematodes: The article is addressing the preservation of germ granules over lineages and how they may play a part in determination, identification, and differentiation of germ cells.The 2 main modes of segregation to preserve the germline of species are inductive mode and preformed mode. Majority of animals have the inductive mode, but nematodes have the preformation mode of development.

1.) Inductive mode (epigenetic), where the germ cells are produced later in the developmental stages through signaling from the surrounding tissues.
2.) Preformation mode, where the germ line has been specified by maternally inherited determinants before or after fertilization.

The preservation of the germ granules and there mechanisms are only understood in the Caenorhabditis elegans. P. Granules are associated with P. Cell lineage in early embryogenesis. The P. Cell lineage is an asymmetrical lineage that gives rise to the germ cell precursors Z2 and Z3. P. Granules cellular function is still unknown, but it is believed to store RNA and proteins, which regulates their expression. Numerous studies and evidence shows us that P. Granule helps in mRNA trafficking, translation, stability, and RNA interference. Recent studies show that P. Granules share a couple of proteins with ribonucleoprotien complexes and stress granules, which are part of degradation of mRNA and in transient storage or protection from stresses. Their study was to increase the database and analysis of other nematodes and the effects of the P. Granules in the preformation mode of development.

They concluded that the distribution of the P. Granules was wide enough to reveal varying levels of conservation among P granule proteins, which in turn may suggest diversity in granule assembly mechanisms in the phylum. Problems that arose from the study suggest germ granule mechanism of assembly and stability may differ greatly across nematodes. The germ granule proteins and functions associated with them might be relatively easy to be incorporated during evolution. Finally, the absence and modification of known germ granule components may reflect deeper differences in underlying molecular mechanisms of germline specification and development in nematodes. Below is a video of my own recording of a single nematode cell developing through stages of development. Some pictures will be blurry or out of focus, sorry for that.

video

Saturday, October 2, 2010

Weekly Developmental Post

I was reading through some articles on developmental biology from Nature, the international weekly journal of science, and i came across a certain article that sparked my interest.

Regenerative medicine: Heart redevelopment, by Richard P. Harvey. In this article it talked about how they are working on creating cardiomyocytes through the use of stem cells along with many different complex steps. They are developing the cardiomyocytes by using 3 different transcription factors (TF) known as Gata4, Mef2c and Tbx5. The Gata TF is thought to help regulate genes in myocardial differentiation and function along with embryogenesis. The encoded Tbx5 protein helps with specification of limb identity and may have a role in heart development. Mef2c TF this gene is involved in cardiac morphogenesis, myogenesis, and vascular development.

They ended up being able to create neonatal mouse cells into cultured cardiomyocyte. The experimenters seen that the cells they created had the properties of cardiomyocytes they were beating, they could identify the myofilaments, and had calcium oscillations similar to those in adult cardiomyocytes. These cells lasted a week in culture and still worked after the transcription factors were turned off.

There is still a lot of work to be done, however this experiment is a step closer and a good start point for further investigation in creating cardiomyocytes for in vitro implantation in heart patients. If they can figure out how to make these cells survive longer and adapt/fuse with the existing tissue and transplant them into heart patients; it would greatly benefit those with heart disease and allow new cells to replace the older/dead cells making the heart work homeostatically.