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Life Lines

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'A trip to the American Museum of Natural History was my idea of being in heaven.' - Elof Carlson

By Elof Axel Carlson

The life sciences are vast in the number of specialties that exist for those pursuing a career as a biologist. A majority of college biology majors are premedical or seek some sort of health-related field. As much as possible they hope the biology they learn will find its way into the health field they seek to enter. Persons who want to be scholars in biology are often motivated by a desire to know as much about life as they can. I was one of those from early childhood when a trip to the American Museum of Natural History was my idea of being in heaven.

Elof Axel Carlson

I loved learning about evolution and the diversity of life. I knew I wanted to be a geneticist when I was in ninth grade and learned about Paul Müller’s Nobel Prize work on inducing mutations. Like a duckling, I felt imprinted and wanted to work with Müller someday.

Graduate work was different. As a teaching assistant I got to see about 90 different specimens each week for the various organ systems displayed by students. Unlike the textbook perfect illustrations, veins and arteries could be slightly off in the specimens I looked at. Their colors differed. Their texture differed.

I also learned how much we didn’t know about life. For my specialty of genetics (with Müller, as I had hoped) I felt steeped in experimental design, techniques and ways of thinking. Doing a Ph.D. allowed me to examine a gene using the tools of X-raying to produce mutations of a particular gene and subtle genetic design to combine pieces of a gene — taking it apart and combining pieces that were slightly different. It gave me an insight into that gene (dumpy, in fruit flies) that for a short time (until I published my work) I was the only person in the world that knew its structure.

In my career I have taught biology for majors, biology for nonscience majors, genetics, human genetics and the history of genetics. I have taught lower division and upper division courses, graduate courses and first-year medical classes. I learned that sharing new knowledge with students excited their imaginations. I learned that the human disorders I discussed led to office visits; and if I didn’t know the information they sought, I went with them to the medical library and we looked up articles in the Index Medicus and discussed their significance.

Often that student was married and had a child with a birth defect (born without a thyroid, having a family trait that might appear like cystic fibrosis). I would prepare a genetic pedigree and give it to the student to stick in a family bible for future generations to read. I also delighted in going to meetings to discuss genetics with colleagues whose work I had read.

I was pleased that I shared a body plan with other mammals. I liked comparative anatomy, which taught me how other body plans work (mollusks, arthropods, worms, coelenterates, echinoderms). As a graduate student taking a vertebrate biology course, I went into a cave and plucked hibernating bats from a ceiling.

The world under a microscope is very different. To see amoebas, ciliated protozoans, rotifers and other organisms invisible to the naked eye or as mere dust-like specks is a thrill. I can go back in time and imagine myself as a toddler, a newborn, an embryo in my mother’s uterus or an implanting blastocyst rolling out of her fallopian tube. I can imagine myself as a zygote, beginning my journey as a one-celled potential organism typing this article into a computer. I can go back in time to my prehistoric ancestors and trace my evolution back to the first cellular organism (bacteria-like) more than 3 billion years ago.

I learned, too, that I contain multitudes of ancestors who gave me one or more of their genes for the 20,000 I got from my father’s sperm and the matching 20,000 genes in my mother’s egg nucleus. I contain some 37 trillion (that is, 37,000,000,000,000) cells or 2 to the 45th power, which means some 45 mitotic cell divisions since I was a zygote. I know that the warmth of my body is largely a product of the mitochondrial organelles in my cells that using the oxygen from the air I breathe and converting small molecules of digested food to provide energy that runs the metabolism of my body and disposes carbon dioxide that eventually is expelled from my lungs. This knowledge makes me aware of my vulnerability at the cellular level, the chromosome level and the genetic level of my DNA to the agents around me that can lead to birth defects cancers, and a premature aging.

Knowing my biology allows me to know my risks as well as new ways to celebrate my life.

Elof Axel Carlson is a distinguished teaching professor emeritus in the Department of Biochemistry and Cell Biology at Stony Brook University.

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Charles Darwin

By Elof Axel Carlson

Elof Axel Carlson

An intellectual pedigree traces the power of mentoring across many generations. I got my Ph.D. in genetics with Nobel laureate Hermann J. Muller at Indiana University. Muller got his Ph.D. in genetics with Thomas H. Morgan also a Nobel laureate at Columbia University. Morgan got his Ph.D. in embryology with William K. Brooks at Johns Hopkins University.

Brooks got his Ph.D. in comparative anatomy with Louis Agassiz at Harvard. Agassiz came from Europe. He got his Ph.D. in ichthyology (fossil and live fishes) with Georges Cuvier in Paris. Cuvier got his doctorate in comparative anatomy from Ignaz Döllinger in Germany. Döllinger got his Ph.D. at Padua in Italy studying embryonic development. He was mentored by Antonio Scarpa at Modena in Italy.

Scarpa was mentored by Giovanni Morgagni at Padua. Morgagni was mentored by Antonio Valsalva who named the Eustachian tube, and he was mentored by Marcello Malpighi an early microscopic anatomist. Malpighi was mentored by Giovanni Borelli who first used physics to describe animal motion relating bones and muscles to function. Borelli was mentored, in turn, by Benedetto Castelli a mathematician and astronomer who studied sun spots. Castelli was mentored by Galileo Galilei.

I followed the history two more generations. Galileo was mentored by Ostillio Ricci. Ricci was mentored by Niccolò Fontana Tartaglia, another mathematician whose text on applied mathematics was a best seller in Renaissance Italy. From my Ph.D. in 1958 to Tartaglia’s years of birth and death (1499-1557) is a span of about 450 years.

If I number Tartaglia as 1, I am generation 16. Not all had a Ph.D. as their highest degree. Some had the M.D. The modern university as a research and teaching institution dates to the late 1700s in Germany. The Medieval and Renaissance university was based on the seven liberal arts leading to the B.A degree. Students could then choose law, medicine, theology,. or philosophy as a specialty leading to a M.A., M.D. or Ph.D. Nicolaus Copernicus got degrees in canon law (laws applied to and by the church), medicine and philosophy.

The M.D. degree until the late 1890s used to require a book-length dissertation as did the Ph.D. Note that German science was influenced by the Italian universities that took an interest in observational and experimental science in the Renaissance. It was Döllinger who brought this tradition back from Padua.

There was no scientific tradition at the university or college level in the United States until the 1870s when Cornell, Yale and Johns Hopkins stressed the Ph.D. as a scholar’s degree. Prior to that most American colleges stressed training for the ministry. Agassiz brought that scholarly tradition to Harvard to bolster American science.

I have done intellectual pedigrees for William Castle, Ralph Cleland, Seymour Benzer, Theodosius Dobzhansky, J.B.S. Haldane, Barbara McClintock and a few other geneticists. They usually differ. That means not all roads lead to Galileo. A few plug in to Agassiz or Döllinger. I was pleased to trace McClintock back to Carl Linnaeus. They are fun to do and you can use Wikipedia for the biography of a scholar you wish to follow. It will give (most of the time) the person who supervised a thesis or the names of that person’s best known students.

I also learned that sometimes there is more than one major mentor in a scholar’s life. Morgan was mentored by Brooks, but he was also mentored by H. Newell Martin who was a student of Michael Foster who was a student of Thomas H. Huxley, who was mentored by Charles Darwin. That means, I too, have a branch that leads to Darwin.

I learned from these pedigrees that we are shaped by what we experience. We are shaped by our parents and their community. We are shaped by mentors in high school or college. Sometimes it is through a course we take. Sometimes it is in our volunteer or extracurricular activities. Also, we have influence on more students than those who come for a Ph.D. research experience. In my career, this can be through the courses I taught, the office visits I had or the chance encounters with students while eating lunch, serving on committees that brought me in contact with them or serving as an academic advisor for my department.

Life gives us opportunities to be thankful. I thank the 15 generations that preceded me in my life as a scientist and teacher. What each generation gave was an opportunity to discover and to learn, to relate and to communicate, to lecture and to write.

Elof Axel Carlson is a distinguished teaching professor emeritus in the Department of Biochemistry and Cell Biology at Stony Brook University.

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By Elof Axel Carlson

Elof Axel Carlson

There are millions of species of living things. Until the 1860s biologists divided them into two kingdoms, animals and plants.

Louis Pasteur revealed a third group of microscopic bacteria that caused disease, fermented foods (like cheeses), rotted food and decomposed dead organisms. In the mid-20th century this third group, known as prokaryotes, was shown to consist of eubacteria and archaea, differing mostly in how they used energy to carry out their living activities.

Bacteria mostly use oxygen, sunlight and carbon dioxide as fuels and an energy source. Some bacteria are like green plants and use chlorophyll to convert carbon molecules to food and release oxygen. Most of Earth’s atmosphere arose from that early growth of photosynthetic bacteria. Archaea mostly use sulfur, superheated water and more extreme environmental conditions (like deep sea vents) for their energy.

Biologists today identify cellular life as having three domains — archaea, bacteria and eukaryotes. We belong to the eukaryotes whose cells have nuclei with chromosomes. The eukaryotes include multicellular animals, multicellular plants, unicellular protozoa (protists), unicellular algae and fungi.

The two prokaryotic domains and the five eukaryotic groups are designated as kingdoms. A rough time table of early life on Earth would put prokaryotic life about 3.5 to 3.8 billion years ago, the first free oxygen in our atmosphere about 3.5 billion years ago, the first eukaryotic cells about 2.5 billion years ago and the first multicellular organisms about 1.5 billion years ago.

The branches of the tree of life biologists construct have an earliest ancestor called LUCA (for the last universal common ancestor of a particular branch). There may have been a biochemical evolution preceding the formation of the first cellular LUCA with RNA and protein associations, RNA and DNA associations and virus-like sequences of nucleic acids.

The three domains have produced six million different genes. Molecular biologists have identified 355 genes that all cellular organisms share in common. This is possibly the genome of the LUCA of all living cellular organisms. Whether such a synthetic DNA chromosome could be inserted into a bacterial or archaeal cell or even a eukaryotic cell whose own DNA has been removed has not yet been attempted. It may not work because we know little about the non-DNA components of bacterial or archaeal cells.

Biologists have known for some time that a nucleus of a distant species (e.g., a frog) placed in a mouse egg whose nucleus has been removed will not divide or produce a living organism. But two closely related species (like algae of the genus Acetabularia) can develop after swapping nuclei. In such cases the growing organism with the donated nucleus resembles the features of the nuclear donor.

There is a LUCA for the first primate branch with the genus Homo. We are described as Homo sapiens. Anthropologists and paleontologists studying fossil human remains have worked out the twigs of the branch we identify as the genus Homo. Neanderthals and Denisovans (about 500,000 years ago) are the two most recent branches that preceded the origins of H. sapiens (about 160,000 years ago). Most humans have a small percentage of Neanderthal or Denisovan genes. Fossils of Homo erectus (about 1.8 million years ago) or Homo habilis (about 2.8 million years ago) are much older than the recent three species of Homo. Those fossils do not have DNA that can be extracted from teeth.

A second objective of studying LUCA’s 355 genes will be the identification of each gene’s function. That will tell biologists what it is that makes these genes essential in all cellular organisms.

I can think of a third important consequence of studying LUCA. There are millions of different viruses on Earth, especially in the oceans. If cellularity arose from clusters of viruses, the genes of the mother of all LUCAs may be scattered among some of those viruses and give biologists insights into the step-by-step formation of that first LUCA cell.

In Gilbert and Sullivan’s operetta, “The Mikado,” one character boasts of tracing his ancestors to a primordial bit of protoplasm. The genome of LUCA might become an unexpected example where science imitates art.

Elof Axel Carlson is a distinguished teaching professor emeritus in the Department of Biochemistry and Cell Biology at Stony Brook University.

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Stock photo

By Elof Carlson

For the past four years I have participated with a writing group at Indiana University’s Emeriti House, where old-timers like me gather and once a month discuss what we have written. I much enjoy listening to the stories told.

A Norwegian opera singer described his youth near Oslo on an island in a fjord and how that idyllic childhood was shattered by the Nazi occupation. A linguistics professor discussed what it is like to eat with one’s hands in Kathmandu where table manners are very different than the world of knives and forks or chopsticks. A Spanish teacher described her adventure learning how to chop wood with a wedge. A journalism professor described sailing a boat alone from New England to Florida and back. Along the way we learned that some growing up experiences were frightening, especially those who were refugees during WWII in the Baltic states.

A different opportunity arose recently when my daughter Christina located the granddaughter of my Uncle Charles Vogel. I had seen him a few times as a child when my mother would visit him at his home in Brooklyn. He sold clothing door to door and he gave me about a dozen ties so I could wear them to my high school. My mother said he sold to gangsters. I never knew if this was part of my mother’s psychotic beliefs or real, but I downloaded this previously unknown relative’s manuscript called “Charlie’s story” based on a 1985 interview she had with her grandfather. It turned out he sold men’s clothes to Al Capone, Gaetano Luchese, Lucky Luciano and Albert Anastasia. He also survived a disastrous childhood accident in Bound Brook, New Jersey, when he was hit by a car that had him hospitalized for a year. Later he ran away to join the Barnum & Bailey Circus until his father located him. These family stories are usually oral and then forgotten after a couple of generations. But if someone types them up after an interview, they can be part of the delight of tracing our ancestors and seeing how things change over several generations.

Social history decays rapidly, and many of us have only scattered memories of our childhood. We know virtually nothing about our grandparents’ or great grandparents’ lives. If we have our DNA examined for selected genetic markers, we can identify different ethnic components (Asian or African or Middle Eastern or Native American). Each person who has a European ancestor is related to virtually every person in Europe if one goes back 2,000 years (something difficult to do for those who do not have a royal lineage).

All Native Americans in the western hemisphere are related to ancestors who lived in eastern Siberia about 15,000 years ago. The genetic crumbs of information of this past ancestry tell us little about who these people were and what they did. But what we preserve as memoirs can last for many generations delighting our descendants. Every time I open up a volume of Samuel Pepys’ diary the world of the 1660s shifts from history to eyewitness narrative.

Elof Axel Carlson is a distinguished teaching professor emeritus in the Department of Biochemistry and Cell Biology at Stony Brook University.

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