Developmental Biology Report prepared by:

John Michael P. Angelo

Registered Professional Teacher

SNCECM Math Coordinator

MAT-Biology Student

Identifying Developmental Genes

Genes that are developingAnimals Plant

Mouse (Mus

musculus)

Zebrafish (Danio

reno)

Fruit fly (Drosophila

melanogaster)

C. elegans

(Caenorhabditis

elegans)

African clawed frog

(Xenopus laevis)

Chick (Gallus gallus

domesticus)

Thale cress

(Arabidopsis thaliana)

Maize (Zea mays L.

spp. mays)

Snapdragon

(Antirrhinum)

Petunia (Petunia

hybrida)

Physcomitrella patens

(physcomitrella

patens)

We can identify developmental genes

by the following comparisons

1. Multicellularity

2. Cell movement

3. Rigidity of the body shape

4. Multicellular stages

5. Meiosis

6. Germline

7. Morphogenesis

8. Plasticity

Multicellularity

The multicellularity of the animals and plants

mechanisms is developed independently.

Explanation:

That mechanism in the comparison of the genes

between the animals and plants makes up the

body plan of plants and animals.

While the homeobox and MADS box genes

existed in last common ancestor, the MADS box

gene plays the role of regulation of plant

development while the homeobox genes are

important in animals.

MADS-Box Genes

This is a conserved sequence motif found in

genes which comprise the MADS-box gene

family.

This box encodes the domain of DNA-binding

MADS. This domain allows to bind DNA

sequences of high similarity to the CC[A/T]6GG

motif known as CArG-box.

The domain of DNA-binding MADS are called

transcription factors.

According to various researchers, the lengths of

this box were in the range between 168 to 180

base pairs and that is the encoded MADS domain

which has the length of 56 to 60 amino acids.

The MADS domain is evolved, according to some

evidences, that there is a sequence stretch of a

type II topoisomerase (or cutting of both strands

of the DNA helix simultaneously in order to

manage DNA tangles and supercoils) in a

common ancestor of all extant eukaryotes.

The name of the MADS-Box Genes

M – MCM1 from the budding yeast

A – Agamous from the thale cress

D – Deficiens from the snapdragon

S – SRF from the human

Agamous – is a gene and transcription factor for

the thale cress.

SRF – also known as Serum response factor

Serum response factor

It is a transcription factor that can be found in

humans.

It is considered very important especially in the

development of the embryo as it has been linked

to the formation of mesoderm.

Function

1. In animals, they are involved in muscle

development, cell proliferation and

differentiation. This ranges from the pheromone

response to arginine metabolism.

2. In plants, they are involved in controlling all

major aspects of development especially in the

development of gametophytes, embryo, seed,

root, flower and fruits in both male and female.

3. They have homeotic functions like the

homeobox (or HOX) genes of animals. While

Agamous and Deficiens for the plants

participates in the determination of floral organ

identity according to the ABC model of flower

development.

4. The flowering time determination is also a factor

in the MADS-box gene. It has been shown to

have an important role in the integration of

molecular flowering time pathways.

The genes of the 4th function are essential for the

timing of the flower bloom correctly and

fertilization helps to ensure it at the time of the

maximum reproductive potential.

Homeobox or Hox Genes

They are a group of related genes that controls

the body plan of the embryo along the anterior-

posterior (or head-tail) axis.

Properties:

1. Protein product is a transcription factor.

2. DNA sequence called homeobox is present

3. This are present in animals because of the

same order of the expression along the head-

tail axis of the developing animal.

Cell Movement

Animals Plants

Motile animal cells Positionally fixed plant

cells

Animal cells are motile.

The tissues may be folded and moved against

each other easily.

On the gastrulation of metazoan, triple layered

system is built (first layer – entoderm, second

layer – mesoderm, third layer – ectoderm)

They may even move to other sites

autonomously.

Plant cells are positionally fixed.

They are trapped in cells which are filled with rigid

walls that are made of cellulose which prevents

the movement of cells and tissues.

The plants form three basic tissue systems

without gastrulation (1st layer – dermal, 2nd layer –

ground and 3rd layer – vascular).

Rigidity of the body shape

Animal Plants

Body plan is clearly

determined in most

parts

Highly regulated by

the environment

Animal body plan is clearly

determined in most parts.

In different life stages, they are mostly clearly

determined by its genes.

If for example, they change their movement to

another place or change their short and long term

behaviour, the body plan may change.

Plant development is highly

regulated by the environment.

They are in variation and characterized by

multiple times occurs also in iterative structures.

The organ proportions and frequency may vary.

Multicellular stages

Animals Plants

One continuously

multicellular stage

They have haploid

and diploid stages.

Animal life cycle is just one

continuously multicellular stage

Many animals undergo one or more

transformation, when their body plan changes

dramatically.

Life cycle of all plants have haploid

and diploid stages.

That life cycle is called alternation of generations.

They are leading to two different body plants

during their life cycle (sporophyte and

gametophyte)

Meiosis

Animals Plants

Gametes are formed

directly through

meiosis.

They undergo no

gametic meiosis, but

a sporic meiosis.

Animal gametes are formed directly

through meiosis.

There is nothing that could be compared to the

gametophyte in plants.

Plants undergo no gametic

meiosis, but a sporic meiosis.

The plants produces spores instead of gametes.

Gametophyte is first formed by mitotic divisions,

then forms the gametes.

Germline

Animals Plants

They set aside

reproductive stem

cells in early

development.

No reproductive stem

cells are set aside in

the early development

of plants.

Animal species set aside reproductory stem

cells in early development.

This decreases the accumulation of mutation.

No reproductory stem cells are set

aside early in development in plants.

Some plants live still certain meristems or

meristem parts more inactive till the gametophyte

is to be formed.

Morphogenesis

Animals Plants

Distinct, complete

body shape

Longer period of

morphogenesis

Animals develop to a

distinct, complete body shape.

Some reorganization may take place during the

animal life stages.

In seldom cases, new structures will develop.

Other animals develop stepwise into different

shapes.

Plants go through a longer period of

morphogenesis.

Plants during their development do not head for a distinct body plan.

Many plants grow and develop on and on till they die.

Meristems which are areas of actively dividing undifferentiated cells allows for iterative growth and the formation of more and more new organs and structures during a plants life.

Resemblance of embryonic stem cells in animals is present yet continually existing during adult life stages.

Plasticity

Animals Plants

They are

determinated early in

development.

Enormous plasticity in

their development is

present.

Animal cells are determined early in

development

Animal cells developed into tissues but they are

clearly determined, but in most cases, they are

irreversibly determined.

Most tissues regenerates from stem cells,

however, occurs at some animal species like

Ambystoma mexicanum.

Plants show an enormous plasticity

in their development.

Axillary meristems often grows out in order to

substitute for the lost part.

Strategies resembles the regeneration of the limb

in some animals.

Whole plants can be regenerated from single

cells.

Form of a plant is strongly affected by

environmental factors such as light and

temperature, results in great variety of

morphologies from the same genotype.

Plant forms affected by

environmental conditions could be of:

1. Branching

2. Height

3. Relative Portions of Vegetative and

Reproductive Structures

That amazing level of plasticity helps plants

compensate for their lack of mobility.