molecularlifesciences:

biologysamazingworld:

Nutrition and The Epigenome

It happens just like that!

‘Oxytricha ‘s two macronuclei (green) and micronuclei (blue) are shown schematically over a size-ranked map of all nanochromosomes (alternatively fragmented chromosomes are fuchsia; the 70 kb mitochondrial genome is shown in red for scale)’

‘Like other ciliates, O. trifallax has two nuclei: a micronucleus, which contains its entire genome, and a macronucleus, which houses an edited version of the genetic material that’s used to run the ship. What’s extraordinary about O. trifallax is the degree to which its macronuclear genetic material has been rearranged. Derived afresh each generation from the micronuclear genetic material through an elaborate process that involves chopping up chromosomes, rearranging genes, deleting virtually all of the noncoding DNA, making multiple copies of the various bits, and capping them with telomeres, it ends up with tens of thousands of “nanochromosomes” that then serve as the templates for producing all the proteins that O. trifallax needs to conduct the day-to-day business of being alive.’

See: 

Tantalizing Glimpses into a Fragmented Genome

The Oxytricha trifallax Macronuclear Genome: A Complex Eukaryotic Genome with 16,000 Tiny Chromosomes

The Oxytricha trifallax Mitochondrial Genome

You Have 46 Chromosomes. This Pond Creature Has 15,600

On parameters of the human genome by Wentian Li

“There are mathematical constants that describe universal relationship between variables, and physical/chemical constants that are invariant measurements of physical quantities. In a similar spirit, we have collected a set of parameters that characterize the human genome. Some parameters have a constant value for everybody’s genome, others vary within a limited range. The following nine human genome parameters are discussed here, number of bases (genome size), number of chromosomes (karyotype), number of protein-coding gene loci, number of transcription factors, guanine–cytosine (GC) content, number of GC-rich gene-rich isochores, density of polymorphic sites, number of newly generated deleterious mutations in one generation, and number of meiotic crossovers. Comparative genomics and theoretical predictions of some parameters are discussed and reviewed. This collection only represents a beginning of compiling a more comprehensive list of human genome parameters, and knowing these parameter values is an important part in understanding human evolution.”

An extremely interesting paper that can be read in full here:

http://www.sciencedirect.com/science/article/pii/S0022519311003717

gunthersilves:

Egyptian Vultures and Genetics, best combination ever!

rhamphotheca:

A diagram showing the structure of DNA, with detail showing the structure of the four bases:adenine, cytosine, guanine and thymine, and the location of the major and minor groove. Along with RNA and proteins, DNA is one of the three major macromolecules that are essential for all known forms of life. Most DNA molecules are double-stranded helices, consisting of two long polymers of simple units called nucleotides, molecules with backbones made of alternating sugars (deoxyribose) and phosphate groups, with the bases attached to the sugars.

(image: Richard Wheeler)                                        (via: Wikipedia)

bpod-mrc:

Balls of String

Inside each of our cells roughly two metres of DNA is packed into a nucleus a thousand times smaller than this full stop. There’s even room to spare – so how does it all fit in? This image from a computer simulation shows how it’s done – special proteins intertwine with the DNA forming a compact structure called chromatin. Over time (moving from left to right in this picture), different proteins (shown here in red and green) pinch together specific areas of DNA (shown in grey), creating loops. These loops are wound tighter as more and more proteins attach, resulting in the neat, compact balls of chromatin on the right. But this isn’t long-term storage – some chromatin loops unravel every few seconds to allow genes on our DNA to be read or repaired before winding up again.

Written by John Ankers

—

• Mariano Barbieri, Mita Chotalia, James Fraser, Liron-Mark Lavitas, Josée Dostie, Ana Pombo, and Mario Nicodemi
• Published in PNAS 109(40): 16173-16178

thenoobyorker:

Object Type: Manuscript
Title: An Introduction to Genetics
Maker: A. H. Sturtevant
Date: 1939
Medium: printed book w/colored plates
Dimensions: 8 x 5 3/4 x 1 3/8; x 10 3/4 open; w/ fold-out leaf x 16 3/4 wide
Significance: Laboratory confirmation of mechanisms of inheritance: genetics

Source: Flickr

(via ohyeahdevelopmentalbiology)

fuckyeahlemurs:

Phylogenetic tree of the lemurs based on mobile genetic elements taken from a paper I just published in PLoS ONE. Link to the article by clicking on the photo.

(Ed.: fascinating! Thank you!)

Quantitative and qualitative assessments of PC1 on canine cranioskeletal shape.

(A) Gray wolf (mesocephalic, ancestor to dogs) (B) Afghan hound (dolichocephalic), (C) Leonberger (mesocephalic), (D) Pug (brachycephalic). (E) Boxplots of PC1 (corresponding breed names are listed in Table S2). (F) Surface scans of a gray wolf skull illustrate morphological changes associated with PC1. Columns (left to right) are dorsal, lateral, and rostral views. Top row: a gray wolf skull morphed by positive PC1. Middle row: a gray wolf skull (no morphing). Bottom row: a gray wolf skull morphed by negative PC1. Pseudocoloring of the gray wolf skull indicates rostrum (ros) and neurocranium (nc). Line indicates width of the zygomatic arches (za).

Schoenebeck JJ, Hutchinson SA, Byers A, Beale HC, Carrington B, et al. (2012) Variation of BMP3 Contributes to Dog Breed Skull Diversity. PLoS Genet 8(8): e1002849. doi:10.1371/journal.pgen.1002849