The model, Sardinia familial, reproduces wrought the process of Meiosis and their chromosomes cross over in Prophesy I (Stern). S. Familial have different crossover frequencies between the slopes in Evolution Canyon; there are higher crossover frequencies on the SF compared to the NFG. One possible explanation of this outcome is the harsh conditions on the South side causing an increase in crossing over. To prove if climate conditions really did have an effect on crossover, we controlled the conditions in lab on common lab strains of dark and tan Sardinia.
Having lab strains of Sardinia familial makes it a good model organism because it has a short life cycle, reduces fruiting bodies, and it’s easy to keep alive. The defining characteristic of the phylum Somatic is the production of four to eight sexual spores in a sac-like cell called an caucus (Lamb). As stated before, S. Familial reproduces through Meiosis where crossover occurs in Prophesy I. The process of meiosis can cause three patterns to arise in ASCII; a 4:4 pattern has four black spores and four tan spores next to each other. This occurs when there is no cross over between the different strains.
A and pattern result from crossover; the set patterns are determined through Meiosis. As soon as Meiosis II is complete and there are four daughter cells in the caucus, the pattern is determined. Mitosis is the final step in completing the process; at the end of meiosis, the four daughter cells divide to produce a total of eight spores. There are five research questions we are trying to answer. What are the challenges in the procedure for mating the different strains? What are the challenges in preparing squashes of peripatetic for scoring ASCII?
What evidence demonstrates crossing over has occurred? What is the crossover frequency under optimal growth conditions? And what is the map distance? I will be referring to these questions throughout this report to better our understanding of the lab’s purpose. In this experiment, we placed four agar blocks from Sardinia on a mating plate. The two different strains, tan and wild type, were alternated so no like strain was next to each other. We placed a lid on the plate and let it incubate for two weeks at room temperature to allow the fungi to reproduce and recombine with the strain next to it.
Once finished incubating, we collected samples from one of the lines of black dots between the gars. We put the samples on a microscope slide o score peripatetic squashes by looking for caucus sacs containing black and tan spores. The crossover frequencies of Type A (4:4) for the combined course data were 6,358; Type B ASCII were 05 ASCII, and Type C ASCII were 4,908. Overall, there were a greater number of non-recombinant. Materials and Methods The experiment started through obtaining a mating plate that was divided with a marker into four sections.
The quadrants were labeled ‘Tan” and “Wild Type”, making sure no same label was next to each other. The working surface was cleaned and two small squares of agar were cut with a cleaned razor blade room the first strain and two small squares of agar from the second strain. The tan and black strains were placed under the correct label on the plate so the same strain was not next to each other. The plate was covered up with a lid and the agar blocks were left to incubate for two weeks at room temperature. After the incubation period was complete, a line of black dots appeared along the dividing lines on the plate.
The squashes were prepared by using an inoculating loop to scrape peripatetic from the center of one of the dividing lines. A sample from the dividing lines was placed on a microscope slide and a drop of water as added followed by a coveralls. A pencil eraser was used to release the ASCII from the peripatetic by pushing down on the coveralls. Under the microscope, the ASCII were observed and recorded to find recombination patterns. The total number of recombinant of Type B ASCII and Type C ASCII was divided by the total amount of the recombinant and non-recombinant counted.
The percentage was calculated by multiplying the previous answer by 100. The map distance was found by dividing the percent of the crossovers by 2 because each crossover produced two spores identical to the parents and two spores that resulted from he crossover. Results Table 1. Caucus Scored Non-recombinant # of Type A ASCII (44) Recombinant Total # of ASCII Total # Recombinant ASCII # of Type B # of Type C Class Data 159 125 136 420 261 Section Data 6,358 5,105 4,908 16,371 10,013 Table 2. Crossover Frequencies Frequency of Recombinant ASCII Frequency of Type B ASCII Frequency of Type C ASCII Ratio B/C Data 62. % 29. 7% 32. 4% . 92 61. 2% 31. 2% 1. 04 (egg Figure 1) Figure 1 is one of the many ASCII groups found of recombinant and non- recombinant under a microscope of xx. The eight ASCII circled in red presents a pattern of crossover between the spore color gene and the centimeter. Crossing over occurred between the spore color and the centimeter due to the evidence of the 2:4:2 and 2:2:2:2 ASCII patterns found in groups similar to Figure 1. This group of ASCII is not a good representation of recombinant, but it gives an idea of what we saw when we searched for the recombinant.
The evidence we obtained from Figure 1 and other groups similar to Figure 1 prove that crossover has occurred between the wild type and tan Sardinia. In the class data, there were 125 Type B recombinant and 136 Type C recombinant cored. Since a total of 420 recombinant and non-recombinant ASCII were found, the crossover frequency of the class data is 62. 1% because we divided the total number of recombinant with the total number of ASCII. The map distance can be calculated as followed: Class: 62. 1%/2=31. 05 units Section: 61. 2%/2=30. Units. This is the distance between the centimeter and its gene from where it crossed over. Discussion This experiment helped to further the understanding of reproduction in Sardinia familial under certain environmental conditions by observing the three types of spaceports patterns. S. Familial reproduced through Meiosis under minimal light and room temperature, creating an assortment of offspring. Two of the spaceports patterns produced are recombinant, 2:2:2:2 and 2:4:2, therefore proving crossover occurred, shown in Table 1 .
Above in Table 2, the recombinant percent frequency of crossover is just over 61% and the map distance is around 30 units. Due to this percentage, believe crossover occurs more often in a certain environment because the percentage frequency is more than 50%. The high crossover frequency reflects map distance; the greater the frequency of combination between two genes, the farther apart they are assumed to be. The lower the frequency, the smaller the distance is between them (Salem). Since map distance can only go up to 50 units, our 30-unit map distance is more than half of the chromosome.
This causes me to believe a lot of cross over happened during the two weeks of incubation. More than half of the ASCII found were crossed over, which causes me to believe Sardinia to has a high amount genetic variation. An organism whose offspring is genetically distinct increases the chances of survival (Salem). Would say S. Nicola has a good chance of reproducing and thriving with the amount of recombinant found during lab. From the results, I conclude the room temperature and minimal light in lab affected the outcome of crossover frequency in Meiosis. Some challenges did arise during the lab.
One issue we faced was the difficulty of placing the agar in the plate; it kept sticking to the razor blade because it was so sticky. Eventually, the agar were placed in the correct positions, it just took awhile to get them there. The other issue occurred during incubation, which caused a lot of the class Sardinia to be unusable, so groups had to share the usable Sardinia. My Sardinia was one of the ones deemed unusable; therefore I had to share another group’s Sardinia. Was surprised to find some differences in the class and section data of recombinant.
In the class data, there were more Type C ASCII than Type B and a 62. 1 % crossover frequency, but in the section data, there were more Type B ASCII than Type C and a 61. 2% crossover frequency. It’s surprising to me how the number of ASCII types in the class and section data were not consistent. I would have assumed there would either be more of Type B or Type C in both analyses. What I find even more surprising is that despite the differences in recombinant amounts, the percentage crossovers are similar. Because the two pieces of data backed each other up, this could mean that S. Nicola has a crossover percentage around 60% if the growth conditions are room temperature and minimal light. When discovering crossover frequencies were consistent between the class and section, the percentages weren’t exactly equal to one another. This could possibly be the result of experimental errors. For instance, when scoring the ASCII, I found it difficult to keep track of the ASCII combinations I already found. There could have been combination patterns counted more than once on the same microscope slide, resulting in inaccurate data.
In future experiments, I would recommend to somehow make aware of the ASCII groups already counted for to be sure the patterns won’t get counted multiple times. Taking a photograph or drawing a picture of ASCII groups would be helpful. To back up the results of the experiment, the lab could be performed again, but differently. For future labs, more data should be collected. Adding more ASCII to the experiment would prove results to be more reliable. A higher amount of data will always have titer, more accurate results because there is more consistency of patterns.
With more data, the process is more understood. Another alteration of the experiment could be changing the temperature and lighting during the incubation period. The temperature could be made cooler to resemble the North Facing Side of Evolution Canyon to prove the correlation of lower crossover frequencies with a lower temperature (Grabbed). Another possibility would be to make the conditions similar to the South Facing Slope by raising the temperature and increasing the light. Based off the current results, I would assume the crossover would be much higher with an increase in temperature and lighting.
The experiment of S. Familial in the lab manual provided evidence that the environment on the South Facing Side causes more cross over between strains. Due to the fact the SF has more light and has a high temperature, I would think lab Sardinia could have an increase in crossover with brighter light and higher heat. This experiment involving Sardinia familial increases the understanding of how it responds to its environment through sexual reproduction. Lamb, Bernard. “Inherited and Environmentally Induced