The Switch that Stops Sex Cells

Scientists better understand how a living organism stops the proliferation of the cells involved in sexual reproduction, thanks to a new study in flies. Noriko Hamada-Kawaguchi and colleagues studied the Wnt signaling pathway in Drosophila, identifying a new regulator of this important pathway, a protein called Btk29A. 

Read more about this research from the 17 January issue of Science here.

[Image courtesy of Noriko Hamada-Kawaguchi. Please click here for more information.]

© 2014 American Association for the Advancement of Science. All Rights Reserved.

The Switch that Stops Sex Cells

Scientists better understand how a living organism stops the proliferation of the cells involved in sexual reproduction, thanks to a new study in flies. Noriko Hamada-Kawaguchi and colleagues studied the Wnt signaling pathway in Drosophila, identifying a new regulator of this important pathway, a protein called Btk29A.

Read more about this research from the 17 January issue of Science here.

[Image courtesy of Noriko Hamada-Kawaguchi. Please click here for more information.]

© 2014 American Association for the Advancement of Science. All Rights Reserved.

Is Somite Formation Off the Clock?

Somites are the segments of a vertebrate embryo that eventually turn into skeletal muscles, skin and vertebrae. Researchers thought that the size, shape and identity of these segments were controlled by a molecular clock, but new experiments with chick and quail embryos suggest otherwise. There isn’t a carefully timed wave of changes that ripples across the embryo to control somite development, say Ana Dias and colleagues. Instead, somites may be generated by local cell-to-cell interactions. 

Read more about this research from the 9 January issue of Science Express here.

[Image courtesy of Dr. Irene De Almeida. Please click here for more information.]

© 2014 American Association for the Advancement of Science. All Rights Reserved.

Is Somite Formation Off the Clock?

Somites are the segments of a vertebrate embryo that eventually turn into skeletal muscles, skin and vertebrae. Researchers thought that the size, shape and identity of these segments were controlled by a molecular clock, but new experiments with chick and quail embryos suggest otherwise. There isn’t a carefully timed wave of changes that ripples across the embryo to control somite development, say Ana Dias and colleagues. Instead, somites may be generated by local cell-to-cell interactions.

Read more about this research from the 9 January issue of Science Express here.

[Image courtesy of Dr. Irene De Almeida. Please click here for more information.]

© 2014 American Association for the Advancement of Science. All Rights Reserved.

A Bare Minimum for the Y Chromosome?

In a study with mice, Yasuhiro Yamauchi and colleagues demonstrate that two genes can substitute for the entire Y chromosome to generate an immature sperm cell that can successfully fertilize an egg and result in viable offspring. While the authors are careful to note that the study does not have any direct implications for human fertility, it may shed light on the variety of genes needed for maintaining normal sperm function.

Read more about this research from the 21 November issue of Science Express here.

[Image courtesy of Monika Ward. Please click here for more information.]

© 2013 American Association for the Advancement of Science. All Rights Reserved.

A Bare Minimum for the Y Chromosome?

In a study with mice, Yasuhiro Yamauchi and colleagues demonstrate that two genes can substitute for the entire Y chromosome to generate an immature sperm cell that can successfully fertilize an egg and result in viable offspring. While the authors are careful to note that the study does not have any direct implications for human fertility, it may shed light on the variety of genes needed for maintaining normal sperm function.

Read more about this research from the 21 November issue of Science Express here.

[Image courtesy of Monika Ward. Please click here for more information.]

© 2013 American Association for the Advancement of Science. All Rights Reserved.

Did You Know…?

Click to watch the slideshow.

Did you know…that the size of a single whole-embryo imaging experiment is comparable to that of the entire book collection of the U.S. Library of Congress?

“Advanced light-sheet microscopes can record dozens of terabytes of data and millions of high-resolution images per day,” writes P.J. Keller in a Review article for the 7 June 2013 special issue of Science on developmental biology that discusses new imaging techniques that will allow developmental activity to be visualized at short or long temporal scales and at ever expanding tissue depths. “The size of a single whole-embryo imaging experiment obtained with this methodology is comparable to that of the entire book collection of the U.S. Library of Congress.” Understanding morphogenesis as a function of cell behavior remains an important goal in biology, though achieving it has been challenging due to the numerous spatial and temporal scales on which morphogenetic events, like cell-to-cell and tissue interactions, operate.

To learn more, see Science’s special issue on developmental biology here and the report here.

© 2013 American Association for the Advancement of Science. All Rights Reserved.

Wings Not Lost, Just Hidden in Some Insects

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A new study shows that decreasing expression of the Hox gene in mealworm beetles, Tenebrio molitor, coaxes wing-like appendages to sprout from certain non-winged segments of their bodies. The finding suggests that other wingless insects could still have wing-development programs that were modified—but not lost—over evolutionary time too.

Read more about this research from the 15 March issue of Science Express here.

[Image courtesy of Takahiro Ohde. Click the image for more information.]

© 2013 American Association for the Advancement of Science. All Rights Reserved.

Tracking Brain Connectivity In Utero

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A new study uses fMRI to watch and quantify the development of brain connections in fetuses of different ages. Many brain disorders like autism, ADHD and dyslexia are thought to arise from disrupted communication in brain networks. Understanding how brain networks form and what events can impact brain connectivity may help researchers identify abnormal brain development earlier and develop targeted treatments.

Read more about this research from the 20 February issue of Science Translational Medicine here.

[Image courtesy of Rob Widdis. Click the image for more information.]

© 2013 American Association for the Advancement of Science. All Rights Reserved.

Cracked Skin and Crocodile Scales

Head of a juvenile Nile crocodile (Crocodylus niloticus). The irregular polygonal scales on the face and jaws of crocodiles are not controlled genetically. Instead, the patterns are generated through a self-organizational process in which the stiff skin cracks in a tensional stress field as the crocodile grows. Click here for more information.

[Photo: Michel C. Milinkovitch and Adrien Debry]

Anyone wishing to use the cover of Science must contact AAAS to request permission to do so.

© 2013 American Association for the Advancement of Science. All Rights Reserved.

Cracked Skin and Crocodile Scales

Researchers have discovered how the scaly skin pattern on crocodile faces and jaws is created. Mammalian hairs, bird feathers, and many reptile scales grow from genetically-controlled processes, but the crocodile’s head scales don’t follow this nearly universal rule. Instead, crocodile face and jaw scales seem to emerge from the physical cracking of skin, which creates distinct, random, non-overlapping polygonal shapes.

Read more about this research from the 29 November issue of Science Express here.

[Image courtesy of Michel C. Milinkovitch; click the image for more information.]

© 2012 American Association for the Advancement of Science. All Rights Reserved.

Coordinating Fruit-Fly Metamorphosis and Growth

A pair of new studies sheds light on the signaling system that helps a fruit fly’s body parts all reach the proper adult size even when early growth is disrupted. In fruit fly larvae, tissues called imaginal discs give rise to the adult appendages. These tissues regenerate in response to damage. When the imaginal discs are injured or grow tumors, they signal to the rest of the larval animal to slow down growth and delay morphogenesis.

Read more about this research from the 4 May issue of Science here and here.

[Image courtesy of Andres Garelli; click the image for caption information]

© 2012 American Association for the Advancement of Science. All Rights Reserved.

Coral Embryos Clone Themselves

Even fairly gentle waves can break apart fragile coral embryos. But, these fragments simply start dividing again, becoming clones of the original embryo. These are the findings of a Brevium in the 2 March issue of Science, which reveals another mode of reproduction in the animal kingdom. Unlike the embryos of multicellular animals, the embryos of reef-building corals lack a protective capsule or membrane. Coral spawning events can produce billions of naked embryos that float at the sea surface, where even gentle or moderate sea breezes generate small white-cap waves.

Read more about this research from the 2 March issue of Science here.

[Image courtesy of Heyward & Negri, AIMS; click the image for caption information.]

© 2012 American Association for the Advancement of Science. All Rights Reserved.

© 2014 American Association for the Advancement of Science. All Rights Reserved.