April 17, 2012 journal club

• When: Tuesday, April 17, 12:15 PM
• Where: Room E6519, BSPH

Lauren McGinnis will be presenting:
Calcium influx-mediated signaling is required for complete mouse egg activation
PNAS 2012, 109: 4169-4174
Miao et al. (Carmen Williams' research group website)

Lauren's comments about this paper:
"Cytosolic calcium oscillations are characteristic of the egg-to-embryo transition. It has been thought that the intracellular calcium that drives egg activation comes from the endoplasmic reticulum, but this paper looks into the necessity for calcium influx across the plasma membrane as a requirement for egg activation, in addition to a function of influx in restoring intercellular calcium stores that are depleted as a consequence of fertilization. I was interested in this paper because the experimental findings potentially provide insight into my project on post-ovulatory aging, and specifically why aged eggs commonly undergo spontaneous egg activation. The Evans lab has found that aged eggs have reduced cortical tension compared to young eggs and this decrease in membrane rigidity may allow additional calcium to enter the cell across the plasma membrane thereby initiating critical signaling pathways to activate the egg."

Seminar - April 10, 2012

Dr. Patrick Allard
[link for research paper and commentary]
Department of Genetics, Harvard Medical School
"Living and reproducing in a complex environment: Assessing the impact of environmental exposures of health using C. elegans"

Tuesday, April 11, 2012
10:30 AM, Room W1020 (Becton-Dickinson Auditorium)
School of Public Health

Seminar - March 27, 2012

Dr. Philip Jordan
[link for research paper]
The Jackson Laboratory
"Polo-like kinase 1 un-SYPs homologs during meiosis I"

Tuesday, March 27, 2012
12:00 PM, Room W1020 (Becton-Dickinson Auditorium)
School of Public Health

Seminar - March 22, 2012

Dr. Aaron Severson
[link for research paper and review]
Department of Molecular and Cell Biology, University of California at Berkeley
"Keeping sisters together: understanding the mechanisms that ensure genome stability during gamete production in C. elegans"

Thursday, March 22, 2012
12:00 PM, Room W1020 (Becton-Dickinson Auditorium)
School of Public Health

March 8, 2011 journal club

When and where: Room W2303, 12:15, Tuesday March 8

Phylis from the Matunis lab will be presenting:

The mammalian Doublesex homolog DMRT1 is a transcriptional gatekeeper that controls the mitosis versus meiosis decision in male germ cells.
Dev Cell 19:612-624
Matson et al. [David Zarkower lab website]

Phylis admits that, "this publication is not related to my field of research. But I find it interesting because it sheds more light on the process that allows mammalian male germ cells to escape meiosis during development."
Agreed! This is a great topic, as the decision of when to stop doing mitosis and start doing meiosis is a fundamental difference between male and female germ cells -- and one of the earliest events of sexual dimorphism!
(And is it just me, or is the term "gatekeeper" being used a lot more to in descriptions of biological processes? Must be a Ghostbusters renaissance.)

Dec. 14, 2010 journal club

When and where:
Room W2303, Tuesday, Nov. 30, 12:15.

Hyo from the Evans lab will be presenting:

Granulosa Cell Ligand NPPC and Its Receptor NPR2 Maintain Meiotic Arrest in Mouse Oocytes
Zhang M, Su YQ, Sugiura K, Xia G, Eppig JJ [Eppig Jax website]
Science, 2010, 330: 366-9

Hyo's comment on her paper choice:
"Mammalian oocytes are arrested at prophase I until signals allow for their meiotic maturation. This paper proposes a mechanism by which the arrest is maintained. The paper is especially interesting to me as I have observed differences in spindle morphology and cortical mechanics in mouse eggs matured in vivo vs. in vitro. If time permits, I will share some of my own findings!"

Oct. 19, 2010 journal club

When and where:
Room E6519 (same as Sept. 21), Tuesday, Oct. 19, 12:15.

Lauren from the Evans lab will be presenting:

L. Lister, A. Kouznetsova, L. Hyslop, D. Kalleas, S. Pace, J. Barel, A. Nathan, V. Floros, C. Adelfalk and Y. Watanabe et al.,
Age-related meiotic segregation errors in mammalian oocytes are preceded by depletion of cohesin and Sgo2
Curr. Biol. 20 (2010), pp. 1511–1521.

... Ah, among the greatest stresses to many a female is the concept that "advanced maternal age" starts at 35. (I get numerous looks of disappointment as I lecture about this in my basic reproductive biology class, and note that it is indeed a biological reality of the way females do meiosis.) Here is Lauren's comments of why she picked this paper:
"It is well known that meiotic segregation errors are more common with increased maternal age, but surprisingly the molecular basis of these meiotic errors are not completely understood. As the trend for women to delay childbearing grows, it becomes critical to understand "what makes a good egg go bad" (this is part of the title of a recent review by Pat Hunt and Terry Hassold). The paper I chose explores the loss of chromosome cohesion as an important factor in age-related meiotic errors. While this is not directly related to my research, this paper helps to address a critical question in the field of reproductive biology that potentially has huge implications for human health."

Also, Hunt and Hassold did a commentary on the three papers on this topic that were published together in this issue of Current Biology:
Hunt and Hassold commentary
Renenkova et al., Curr. Biol. 20 (2010), pp. 1529–1533
Chiang et al., Curr. Biol. 20 (2010), pp. 1522–1528

March 9, 2009 meeting

We'll meet on March 9 at 12:00 noon in Room W2303 (back to our usual room on the second floor of the SPH, around the corner from the Daily Grind).
Min-Young Kim from the Drummond-Barbosa lab will be presenting -

A spindle assembly checkpoint protein functions in prophase I arrest and prometaphase progression
Science (2009) 329:991
Homer, Gui, and Carroll

Min-Young's comment about this paper:
"The anaphase promoting complex (APC) is a multisubunit E3 uibquitin ligase. The APC mediates degradation of cell cycle regulators. Direct binding of the APC activators, Cdc20 or Cdh1, is critical for target specificity and the timing of the APC activation. During mitosis, it is known that a component of Spindle Assembly Checkpoint complex (SAC), BubR1 inhibits the APC/Cdc20 until all chromosomes are properly aligned on metaphase plate. However, it is still unclear how the APC activity is controlled during meiosis. This paper has shown that BubR1 affects the stability of Cdh1 instead of Cdc20 during meiosis in mouse oocytes. This is a noteworthy finding in cell cycle study."

(and a special thank-you to Min-Young for being willing to present in her first year here at JHU!)

February 23, 2010 meeting

Lauren Matthews will be presenting at our next meeting.
Two things to note for this meeting:
TIME - 12:00 noon (we have switched from our 12:30 start time)
PLACE - E6519 (but just for this meeting)

And of course, also the paper! Lauren will be presenting:
Spindle Positioning in Mouse Oocytes Relies on a Dynamic Meshwork of Actin Filaments
Current Biology, 18: 1514-1519
Azoury et al.

Her comment on why she picked this:
"I like this paper because it focuses on how mouse oocytes position their spindle during meiosis. While it is well known that actin is required for spindle positioning, this group was the first to visualize the presence of a cytoplasmic actin meshwork in live mouse oocytes. Cool techniques coupled with some great egg biology = an awesome paper!"