"On the Replication of Desoxyribonucleic Acid (DNA)" (1954), by Max DelbruckIn 1954 Max Delbrück published "On the Replication of
Desoxyribonucleic Acid (DNA)" to question the semi-conservative DNA
replication mechanism proposed that
James Watson and
Francis Crick had
proposed in 1953. In his article published in the Proceedings of the
National Academy of Sciences, Delbrück offers an alternative DNA
replication mechanism, later called dispersive replication. Unlike other
articles before it, "On the Replication" presents ways to experimentally
test different DNA replication theories. The article sparked a debate in
Max Ludwig Henning Delbruck (1906–1981)Max Ludwig Henning Delbrück applied his knowledge of theoretical
physics to biological systems such as bacterial viruses called
bacteriophages, or phages, and gene replication during the twentieth
century in Germany and the US. Delbrück demonstrated that bacteria
undergo random genetic mutations to resist phage infections. Those
findings linked bacterial genetics to the genetics of higher organisms.
In the mid-twentieth century, Delbrück helped start the Phage Group and
Phage Course in the US, which further organized phage research. Delbrück
also contributed to the DNA replication debate that culminated in the
1958 Meselson-Stahl experiment, which demonstrated how organisms
replicate their genetic information. For his work with phages, Delbrück
earned part of the 1969 Nobel Prize for Physiology or Medicine.
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Richard Doll was an epidemiologist and public figure in the twentieth and early twenty-first centuries. Working primarily at the University of Oxford, in Oxford, England, Doll established a definitive correlation between cigarette smoking and lung cancer. Furthermore, Doll's work helped legitimize epidemiology as a scientific discipline. Doll's research also helped establish modern guidelines for oncological studies, as well as for contemporary and future research on the effect of smoking on pregnancy and fetal development. In addition to studying the health effects of smoking, Doll also studied cervical cancer and contraceptives.
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In her 2001 paper "Predictors of Postpartum Depression: An Update," researcher Cheryl Tatano Beck presents the most common risk factors associated with postpartum depression in women. Postpartum depression occurs when women experience symptoms such as tearfulness, extreme mood changes, and loss of appetite for a lengthened period after giving birth. At the University of Connecticut in Storrs, Connecticut, nursing professor Beck updated a previous study of hers by analyzing literature about postpartum depression published in the 1990s. Beck found four predictors of postpartum depression that she had not included in her previous study. "Predictors of Postpartum Depression: An Update" presents risk factors that healthcare professionals can use to predict whether pregnant women are more likely to develop postpartum depression.
Oliver Allison Ryder III (1946– )Oliver Allison Ryder studied chromosomal
evolution and endangered
species in efforts for wildlife conservation and preservation at the San
Diego Zoo in San Diego, California. Throughout his career, Ryder studied
breeding patterns of endangered species. He collected and preserved
cells, tissues, and DNA from endangered and extinct species to store in
the San Diego Frozen Zoo, a center for genetic research and development
in San Diego, California. Ryder and his team also sequenced vertebrate
genomes under the Genome 10k initiative, a collaborative international
program aiming to analyze the complete genomes of over ten thousand
species of vertebrate. Ryder’s research has helped preserve species,
restore diminished populations of wildlife, and protect biodiversity.
Torsten Wiesel (1924– )Torsten Nils Wiesel studied visual information processing and development in the US during the twentieth century. He performed multiple experiments on cats in which he sewed one of their eyes shut and monitored the response of the cat’s visual system after opening the sutured eye. For his work on visual processing, Wiesel received the
Nobel Prize in Physiology or Medicine in 1981 along with David Hubel and Roger Sperry.
Shoukhrat Mitalipov and Masahito Tachibana's Mitochondrial Gene Replacement Therapy TechniqueIn 2009, Shoukhrat Mitalipov, Masahito Tachibana, and their team of
researchers developed the technology of mitochondrial gene replacement
therapy to prevent the transmission of a mitochondrial disease from
mother to offspring in primates. Mitochondria contain some of the body's
genetic material, called mitochondrial DNA. Occasionally, the
mitochondrial DNA possesses mutations. Mitalipov and Tachibana,
researchers at the Oregon National Primate Research Center in Beaverton,
Oregon, developed a technique to remove the
nucleus of the mother and
place it in a donor
oocyte, or immature
egg cell, with healthy
Stafford Leak Warren
(1896–1981)Stafford Leak Warren studied nuclear medicine in the
United States during the twentieth century. He used
radiation to
make images of the body for diagnosis or treatment and developed the
mammogram, a breast imaging technique that uses low-energy X-rays to
produce an image of breasts. Mammograms allow doctors to diagnose
breast cancer in its early and most treatable stages. Warren was
also a medical advisor to the Manhattan Project, the US government’s
program to develop an atomic bomb during World War II, and he was
responsible for the health and safety aspects of the Trinity Test,
the first atomic bomb test in the US. Warren’s invention of the
mammogram has allowed physicians to diagnose breast cancer in women
during its most treatable stages, preventing deaths due to breast
Neonatal Respiratory
Distress Syndrome and Its Treatment with Artificial SurfactantNeonatal
respiratory distress syndrome, previously called
hyaline membrane disease, is a respiratory disease affecting
premature newborns. Neonatal
respiratory distress syndrome involves shallow breathing, pauses between breaths that last
a few seconds, or apnea, and a bluish tinge to the infant’s skin.
The syndrome occurs when microscopic sacs called alveoli in infant
lungs do not produce surfactant, a liquid that coats the inside of
the lungs and helps them inflate during breathing. Respiratory
distress syndrome is the leading cause of death among premature
Mary-Claire King
(1946– )Mary-Claire King studied genetics in the US in the
twenty-first century. King identified two
genes associated with
the occurrence of breast cancer,
breast cancer 1 (BRCA1)
and
breast cancer 2 (BRCA2). King showed that mutated
BRCA1 and
BRCA2 genes cause two types of
reproductive cancer, breast and ovarian cancer. Because of
King’s discovery, doctors can screen women for the inheritance
of mutated BRCA1 and
BRCA2 genes to evaluate their risks
for breast and ovarian cancer. King also demonstrated the
