Health risks associated with disturbing the internal clock

internal clock
The body’s internal clock, or circadian rhythm, responds to light/dark cycles and is important for health.

Some mornings I wake up just before my alarm is about to go off. If you keep a very regular sleeping schedule, this might happen to you, too. But how does my body “know”, when I’m unconscious, that it’s time to wake up? The answer is that I have an internal clock, which responds to a 24-hour light/dark cycle and wakes me up at my normal time. We don’t know all the details of how it works, but it is controlled in a part of the brain called the hypothalamus.

With modern artificial light sources being so prevalent, it would be very easy to disrupt the clock in such a way that it would no longer function correctly. Working night shifts, traveling to new time zones, and other clock-disrupting behaviors have been correlated with increased risk of certain diseases.

An article in the July 25th issue of Current Biology addresses whether there is a causal relationship between disrupting the clock and health risks and whether long-term disruption could lead to chronic risk. Continue reading

Regeneration

Zebrafisch
The zebrafish is a vertebrate model organism, commonly used for development studies. photo credit: wikipedia

Last month, my husband and I went camping, and I suffered a pretty severe sunburn on the tops of my shoulders. As I watched the healing process, I was amazed (yet again) at the capacity of the skin to regenerate itself! I had seen an article on regeneration earlier this year, so I decided to revisit it for this post. In the article “Mechanosensory organ regeneration in zebrafish depends on a population of multipotent progenitor cells kept latent by Schwann cells” (Sanchez et al., BMC Biology, 2016), the authors investigate regeneration of part of the animal’s sensory nervous system after damage.

Regeneration would not be possible without stem cells and their capacity to replace tissues composed of multiple cell types. During development, cells take on a particular form and function within the body, a process known as differentiation. Stem cells are undifferentiated and thus have the potential to produce any type of cell. A multipotent progenitor cell is a more specialized cell that can still produce many different cell types, but usually the types are restricted to those of a particular tissue or organ. In mammals and humans, many tissues lack the ability to regenerate. Skin and liver are well-known exceptions. However, in many organisms, an entire limb could be cut off and would regenerate  Continue reading

The emergence of antibiotic resistance

Antibiotic_resistance_cartoon
This is one of my favorite cartoons. Sharing segments of DNA is just one of the ways that bacteria can gain the ability to survive antibiotics. (When I searched online for the source of this cartoon, I was unable to find out where it came from. It appears on numerous blogs and websites. If it is yours, please let me know, and I will add proper attribution.)

The June 6th issue of Current Biology contains an article in which Lin and Kussell describe and model the emergence of antibiotic resistance in engineered populations of E. coli (Complex Interplay of Physiology and Selection in the Emergence of Antibiotic Resistance).

Antibiotic resistance is a hot topic in human health because of the recent prevalence of “super-bugs” like MRSA (Methicillin-Resistant Staphylococcus aureus) and CRE (carbapenem-resistant Enterobacteriaceae; a family of bacteria including E. coli, Salmonella, Yersinia, etc.), which are difficult to treat because of the large number of antibiotics to which they are resistant.

Antibiotic resistance is the ability to survive (and possibly even thrive) during drug treatments Continue reading

An amazing trans-generational protein

Meiosis arrest
Eggs arrest in metaphase of meiosis 1 from birth until reproductive age, a period of months to decades, depending on the animal. Maternal (yellow) and paternal (blue) pairs of chromosomes line up at the center of the spindle (green). They can also exchange material resulting in hybrid chromosomes (with blue and yellow regions), which is important for genetic diversity.

In a Current Biology article from April, 2016, Smoak et al. found that a protein which is critical for reproductive health is amazingly stable and, in fact, trans-generational (Long-term retention of CENP-A nucleosomes in mammalian oocytes underpins transgenerational inheritance of centromere identity).

My initial disclaimer here is that this topic is not, strictly speaking, outside my area of expertise, since it relates to cell biology and genetics. That means I will have to be even more careful not to lapse into jargon as I write.

Genetic information is stored in a molecule called DNA, in which the sequence of 4 different bases (A, T, C, and G) make up the genetic code. Based on this code, a cell can make proteins that it needs to carry out whatever tasks and functions it is supposed to do. DNA is organized into chromosomes (the X-shaped structures in the image above), which also contain many proteins whose job is to maintain the integrity of the chromosome itself as well as to package the DNA so that it fits in the cell’s nucleus. In addition, some proteins can confer unique identities to parts of the chromosome, such as the circle in the center of the ‘X’, known as the centromere. The centromere is one region of the chromosome where the DNA sequence does not matter. Instead it is the proteins associated with that region of the DNA that dictate its purpose. The centromere serves as a docking site for the small tube-shaped filaments (‘microtubules’ shown in green) that will pull the chromosomes to opposite sides of the cell before the cell divides, in order to ensure that each daughter cell obtains all of the appropriate chromosomes.

In humans, there are 23 pairs of different chromosomes (only three pairs are shown in the image above for simplicity). Eggs and sperm have only one of each chromosome, so that when they get together, a new full set exists in the fertilized egg. When eggs and sperm cells are produced, they undergo a specialized version of cell division that reduces the number of chromosomes by half. Females are born with all of their eggs arrested in metaphase of meiosis 1, as shown in the image above. The eggs remain in this state until after puberty, when they begin to mature (i.e. finish meiosis), at the rate of one per month, at which point they are capable of being fertilized. When the eggs run out, reproduction is no longer possible for the female.

Even before most women’s egg supplies are exhausted, Continue reading

What’s in my gut?

F1.medium
COVER of SCIENCE: Artist’s interpretation of a person’s gut microbiome. ILLUSTRATION: Nigel Sussman

 

The April 29th issue of Science magazine features a special section on the gut microbiome. This seems like a great place to start my blog, because it’s a topic I’ve been interested in for a long time.

A large group of authors from Europe published an article titled: “Population-level analysis of gut microbiome variation” (Falony, Joossens, Vieira-Silva, Wang, et al.).

The gut microbiome refers to the communities of bacterial species that live in our intestines. Most of them are there providing some benefit to the host (me or you). In fact, this is where the term “probiotic” comes from: the idea that some bacteria are good and helpful. Although we tend to think of bacteria as “germs” that make us sick, we have in us and on us numerous bacteria that are keeping us alive and well. I’ve heard it said here that the human body consists of 10 times more non-human cells than human cells and as many as 100 times more non-human genes than human genes! Continue reading

Introduction

I am a postdoctoral research scientist, with a B.S. in Biology and a Ph.D. in Molecular Genetics. Right now I’m working in a lab studying a small soil worm. In the process of trying to understand how the cells in the worm organize themselves, I’m using CRISPR (“crisper”) technology to make some proteins fluorescent. As my friends like to say, I’m “making glow worms.”

I’m starting this blog to help accomplish some goals I have for improving my broad based knowledge of biological sciences and gaining experience in science writing for non-scientists. I plan to find recently published articles relating to aspects of biology that are outside my expertise and convey the information and impact in a way that a general audience or someone interested but not trained in science could understand.

I hope you’ll come along with me on this journey, and that we can dabble in biology together.