Introduction

 

In the winter of 2000, a major human goal was finally accomplished -

The human genome project was completed. Using techniques such as RFLP

mapping as well as high and low resolution physical mapping, all 100,000

genes in human DNA were identified (U. S. 28-30). With this enormous task

completed, scientists asked themselves, where do we go from here? Will we

be able to reconstruct the major steps in the evolution of life on earth

(Collins 91)?

In their research of genetic linkages, Rogers et al. further posed the

question: what does medical research have to gain from a better

understanding of the genetic similarity between humans and our close

evolutionary relatives? Starting with published human primers, linkage maps

of baboons were constructed employing techniques such as PCR, gel

electrophoresis and computer mapping. The goal of this experiment is to see

how closely baboons and humans are related genetically and if this

evolutionary relationship is discovered, other nonhuman primate linkage

maps can be constructed, thus creating new opportunities in biomedical

technologies and in evolutionary genetics (Rogers 245).

 

 

Body

 

Methods: In the experiment performed by Rogers et al. published human

PCR primers were used to amplify homologous microsatellite loci from the

baboon genomic DNA. To identify human primer pairs that would

successfully amplify baboon polymorphisms, more then 1300-primer pairs

were screened using panels of unrelated baboons. Wide ranges of PCR

conditions (annealing and solution concentrations) were used to increase the

probability of success at each locus. Next the radiolabeled primers were used

to identify the genotypes of the baboons by means of gel electrophoresis.

The resulting genotypes lead to the construction of a multipoint linkage map

for each baboon chromosome by special modeling software used for

twopoint linkage analysis (Figure 1.). Out of the 331 reported markers, 293

were placed into a comprehensive map of 286 markers mapped with

likelihood ratios of greater then or equal to 1000:1 and 7 markers were

mapped with the likelihood of ratios of greater than of equal to 100:1

(Rogers 242).

 

 

 

 

 

 

Results: The results of the experiment further supported the hypothesis of

the genetic link between humans and nonhuman primates. There were seven

human autosomes for which the baboon homologues show the same order

among loci. In three different cases, baboon chromosomes consist of the

fusion of two human chromosomes. The experiment also revealed that

human chromosome 2 is the result of evolutionary fusion unique to human

lineage (Rogers 243). The biggest finding was that recombination distances

in baboons are shorter than in humans, which implies that humans have a

higher rate of recombination. The genome size in humans (3500cM) is also

quite a bit longer then in baboons and domesticated animals (3000cM). This

is an odd finding since the amount of DNA in all mammals should be

approximately equal (Rogers 245). (Figure 2.)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Conclusion

 

" The linkage map produced in this experiment can serve as a basis for

developing equivalent maps for rhesus macaques, as well as other closely

related species. The polymophoric loci analyzed here will also be valuable

for studies of the genetic variability and population genetic structure of

natural populations of baboons" (Rogers 245). Rogers et al. also believes

that the development of linkage maps of various primates will create

research opportunities in biomedical and evolutionary genetics, including

comparative genomics and genome scanning for single-locus traits (245).

In addition to medical benefits, by studying baboons and other closely

related species we can possible model specific behavior, reactions and

characteristics in humans by using an evolutionary relationship. It may be

possible in the future to use what we know about genetic linkage between

humans and other species to understand specific behavior in animals.

 

 

 

 

 

 

 

 

 

 

 

References

Collins, Francis S. and Karin G. Jegalian. December 1999.

"Deciphering the Code of Life." Scientific American: 86-91.

Rogers, Jeffrey et al. August 2000. " A Genetic Linkage Map of the Baboon (Papio hamdryas) Genome Based on Human Microsatellite

Polymorphisms." Genomics: 237-247.

U.S. Congress, Office of Technology Assessment 1998. Mapping our Gene.

U.S. Government printing Office. Washington, D.C.

 

 

 

 

By: Danielle Arnold, Amy Tisdell, Katie Schaetzle and Roger Rothschild

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Genomics: Benefits of a cross-species study

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Contributions

Even though different jobs were assigned Amy, Danielle, Katie and Roger all shared equally the amount of work that was needed to complete the poster.