Hoxful Monsters

To define Segmentation in simple terms would be division of animal bodies into repetitive segments.Segments are comprised of a number of discrete structures developmentally derived from both ectoderm and mesoderm.Segmented animals are found in Annelida,Arthropoda and chordata phylas which are not closely related according to recent phylogenic data.Segmentation allows for a high degree of specialization of bodily regions.
Among Chordata, segmentation is well characterised in vertebrates.Segments or Somites in vertebrates are transient mesodermal structures that form sequentially along the anterior–posterior axis with a regular spatial and temporal periodicity.Molecular data available so …

Classification of Fossils is sometimes tricky as they do not follow systematics of living organisms and here come stem groups to the rescue.In order to know about stem groups we need to understand Crown Group also.
Stem groups:
Stem group organisms always lack one or more features that are present at the base of the crown group to which they are attached.

Archaeopteryx
Originally uploaded by Sebastian
Niedlich (Grabthar)

Crown Group:
A crown group is a living clade or monophyletic group which consists of the last common ancestor of all living examples and all of its descendants.But …

Embryology is the study of the development of an embryo. An embryo is defined as any organism in a stage before birth or hatching, or in plants, before germination occurs.Embryology refers to the development of the fertilized egg cell (zygote) and its differentiation into tissues and organs. After cleavage, the dividing cells, or morula, becomes a hollow ball, or blastula, which develops a hole or pore at one end.

10-day old chicken embryo
Originally uploaded by Ego Sum Daniel

In animals, the blastula develops in one of two ways that divides the whole …

Nature journal has published an article under career view in 2006 from Georgia Chenevix-Trench,a principal research fellow at the Queensland,Institute of Medical Research, Royal Brisbane Hospital, Herston, Australia.She talks about what makes a good PhD student which i found it very interesting and might help many students who are pursuing or might take PhD in the furture.
Doing a PhD should be fun and rewarding, because you can spend all your working time discovering things and pursuing ideas — and getting paid for it, without any administrative responsibilities. Those who stick …

Lots of confusion prevailed in nomenclature Hox genes , even the name Hox was confusing.A hox gene originally referred to any gene coding for a protein with Homeodomain.In the beginning very few genes where known which could be clearly identified with homeotic mutants of Drosophila.Later huge number of genes with Homeodomain were identified which does not show homeotic property(transforming one segment to another when mutated).So the name HOX became ambiguous.But now the general consensus is that the term Hox is used only for …

At first, the embryo is just a small mass of cells. As it develops, it has to ‘know’ where its top and bottom are, as well as its front and back, and left and right sides. Different cells of the embryo grow into their designated organs and body parts. All must grow in the right place, and to the right size. Surprisingly, many of the genes that control the early embryo development of organisms such as mice, chickens and fruit flies are very similar to Human’s.
An animal’s body results …

These days i am mostly into understanding the various aspects of evo devo and for this i am trying to read loads of articles.Things will be fine for me till i encounter a phylogenetic tree ,which is not an easy thing to understand if you are new to this field.No way you can bypass phylogenetic trees in the field of evolution as it forms the heart of the subject.Initially it was very torturous to read this confusing trees but things slowly getting better with discussion (with my friend) and reading …