Biological Sciences

At the gastroesophageal junction, most vertebrates possess a functional lower esophageal sphincter (LES)
which may serve to regulate the passage of liquids and food into the stomach and prevent the reflux of
gastric contents into the esophagus. Snakes seemingly lack an LES and consume meals large enough to
extend anteriorly from the stomach into the esophagus thereby providing the opportunity for the reflux
of gastric juices. To explore whether snakes experience or can prevent gastric reflux, we examined postfeeding
changes of luminal pH of the distal esophagus and stomach, the fine scale luminal pH profile at
the gastroesophageal junction, and the morphology of the gastroesophageal junction for the Burmese
python (Python molurus), the African brown house snake (Lamprophis fuliginosus), and the diamondback
water snake (Nerodia rhombifer). For each species fasted, there was no distension of the gastroesophageal
junction and only modest changes in luminal pH from the distal esophagus into the stomach. Feeding
resulted in marked distension and changes in tissue morphology of the gastroesophageal junction. Simultaneously,
there was a significant decrease in luminal pH of the distal esophagus for pythons and house
snakes, and for all three species a steep gradient in luminal pH decreasing across a 3-cm span from the
distal edge of the esophagus into the proximal edge of the stomach. The moderate acidification of the
distalmost portion of the esophagus for pythons and house snakes suggests that there is some anterior
movement of gastric juices across the gastroesophageal junction. Given that this modest reflux of gastric
fluid is localized to the most distal region of the esophagus, snakes are apparently able to prevent and
protect against acid reflux in the absence of a functional LES.

Background: There is a negative relationship between education and religiosity and a positive relationship
between education and acceptance of evolution, but how this manifests in college students who differ in degree
of religiosity and prior educational experiences is unclear. We focused our study on the relative importance of
education and religion on evolution understanding for college students at a large, public university in the Deep
South.
Methods: We used a structural equation model incorporating both acceptance and knowledge of evolution to
evaluate the relative influence of religion and education on evolution understanding of 2,999 surveyed students.
We further focused on acceptance of evolution and academic level, college major, high school experience, religion,
and religiosity. We conducted pre and post course evaluations in three biology classes, and finally we tested the
relationships between the quality of K-12 state science standards and states’ religiosity and educational attainment.
Results: We found that the degree of religiosity mattered significantly more than education when predicting
students’ understanding of evolution. When we focused on acceptance of evolution only, students taught
evolution or neither evolution nor creationism in high school had significantly higher acceptance than those taught
both evolution and creationism or just creationism. Science majors always outscored non-science majors, and not
religious students significantly outperformed religious students. Highly religious students were more likely to reject
evolution even though they understood that the scientific community accepted the theory of evolution. Overall,
students in two of three biology classes increased their acceptance of evolution, but only those students that
seldom/never attended religious services improved. K-12 state science standard grades were significantly and
negatively correlated with measures of state religiosity and significantly and positively correlated with measures of
state educational attainment.
Conclusions: Religiosity, rather than education, best explains views on evolution. In areas of the country where the
vast majority of residents believe in God and the literal truth of the Bible, students may be hampered as they enter
and progress through college. These same states tend to have lower state science standards and lower levels of
educational attainment

Sister chromatid cohesion is fundamental for the faithful transmission of chromosomes during both meiosis and mitosis. Proteins involved in this process are highly conserved from yeasts to humans. In screenings for sterile animals with abnormal vulval morphology, mutations in the Caenorhabditis elegans evl-14 and scc-3 genes were isolated. Defects in cell divisions were observed in germ line as well as in vulval and somatic gonad lineages. Through positional cloning of these genes, we have shown that EVL-14 and SCC-3 are likely the only C. elegans homologs of the yeast sister chromatid cohesion proteins Pds5 and Scc3, respectively. Both evl-14 and scc-3 mutants displayed defects in the meiotic germ line. In evl-14 mutants, synaptonemal complexes (SCs) were detectable but more than the usual six DAPI (4′,6′-diamidino-2-phenylindole)-positive structures were seen at diakinesis, suggesting that EVL-14/PDS-5 is important for the maintenance of sister chromatid cohesion in late prophase....

We describe phenotypic characterization of dli-1, the Caenorhabditis elegans homolog of cytoplasmic dynein light intermediate chain (LIC), a subunit of the cytoplasmic dynein motor complex. Animals homozygous for loss-of-function mutations indli-1 exhibit stochastic failed divisions in late larval cell lineages, resulting in zygotic sterility. dli-1 is required for dynein function during mitosis. Depletion of thedli-1 gene product through RNA-mediated gene interference (RNAi) reveals an early embryonic requirement. One-celldli-1(RNAi) embryos exhibit failed cell division attempts, resulting from a variety of mitotic defects. Specifically, pronuclear migration, centrosome separation, and centrosome association with the male pronuclear envelope are defective indli-1(RNAi) embryos. Meiotic spindle formation, however, is not affected in these embryos. DLI-1, like its vertebrate homologs, contains a putative nucleotide-binding domain similar to those found in the ATP-binding cassette tra...