Mosses produce Scents that Attract

Photo: Erin Shortlidge, Portland State University

I am a little behind in posting about the moss research that came out in the journal Nature a couple of weeks ago. Researchers found that a moss with separate sexes produce volatile compounds (scents) that can attract microinvertebrates, which in turn increases sexual reproduction.

Todd N. Rosenstiel, Erin E. Shortlidge, Andrea N. Melnychenko, James F. Pankow, & Sarah M. Eppley. Sex-specific volatile compounds influence microarthropod-mediated fertilization of moss. Nature. doi: 10.1038/nature11330

 

For some additional science news coverage of the research check out these articles below.

Science News - I really like this article. The journalist did a nice job of contacting other science experts, some of whom I know, to comment on the research.

New York Times - Pretty brief article, but I was glad to see they covered it. 

News Release from Portland State University - All the details and contacts. Also the title is super catchy.

This research connects to and builds on an earlier study that demonstrated that microarthropods increase fertilization rates in mosses. Now there is good evidence that the mosses are attracting the microarthropods to assist in sperm movement

Cronberg, N., R. Natcheva, and K. Hedlund. 2006. Microarthropods Mediate Sperm Transfer in Mosses Science 313: 1255. 

This research is really changing our thoughts on how we think about sexual reproduction in mosses. Animals help to move the sperm around. The plants produce scents to attract them. And even if they do dry out some sperm can survive desiccation (study below).

Shortlidge, E. E., Rosenstiel, T. N. and Eppley, S. M. 2012. Tolerance to environmental desiccation in moss sperm. New Phytologist 194: 741–750.

Overall I think it is really interesting research to read and think about. 

August 2012 Desktop Calendar

The summer has been in full swing here with science meetings, summer research projects, and manuscripts almost submitted. I have also been gearing up for a large vacation to France. This is the first big one that I have had since I visited Malaysia and Indonesia in 2010. I think that a big vacation needs to be on my calendar every too years.

Speaking of calendars, I dropped the ball on the calendar for July, but here is the August calendar. Ready to go a day in advance! If your first thought was that this is not a moss then you would be correct. The mosses decided to take a August vacation too! Instead the underside of a fern frond from my trip to Malaysia has taken its place. I hope that you have a great vacation month. Take some time to enjoy nature and recharge. Cheers!

If you are interested in downloading this desktop calendar follow the instructions below. 

1 - Single click on the image to open it up in a new window. (If you use the image directly from the blog post you will loose a lot of resolution.)

2 - Right-click (or ctrl-click) on the image, and chose the option that says, "Set as Desktop Background" or "Use as Desktop Picture". The wording may vary.

3 - If the image does not fit your desktop neatly, you may have to adjust the image (Mac: System Preferences > Desktop > Screen Saver > Desktop; Windows: Control Panel > Display > Desktop) and choose "Fill screen" as the display mode of your background image.

Any issues or suggestions please let me know. These calendars are an experiment in-progress.

A Sporophyte Gone Wild

What happens when a moss sporophyte's calyptra does not detach properly? Really odd development! I came across this sporophyte in one of my Funaria hygrometrica cultures recently.

Calyptra Recap: The calyptra is a small cap of gametophyte tissue that covers the moss sporophyte apex during its development. It is necessary for proper capsule and spore formation in moss sporophytes. Studying the calyptra-sporophyte interaction was the focus of my dissertation research. (You can read more about my main findings here. The calyptra has a cuticle. - The calyptra cuticle develops early relative to the sporophyte cuticle.)

So, this really odd development. It looks like the calyptra did not detach from the rest of the leafy gametophyte properly. Usually there is a line of dehiscence at the bottom that allows the calyptra to separate as a distinct cap. In this specimen the calyptra appears to have split open down the side with the sporophyte continuing to grow. As usual, sporophytes without their calyptra on top do not develop a capsule at all and instead produce an obconic-shaped sporophyte.

On this sporophyte, the apical region and seta meristem both appear to have turned brown and died. Also, there is a funny little projection of tissue sticking off the right side of the thickened stalk. (There is a zoomed-in photo below.) I don't think that I have ever seen anything that looks like this on a sporophyte before!

What is it? Is it branching? Maybe. Is it the beginning of a leaf? Probably not. It would be really cool to section it and see what the internal anatomy looks like. Does it have  central strand tissue going out into it? It looks pretty small so probably not. I wonder if I saved this sample in the lab after taking some photos of it so that I can process it for some anatomical study. Either way, I think that it is some pretty cool morphology to think about!

 

On the Left: An close-up of the sporophyte breaking through the side of the not detached-calyptra. On the right: An up-close view of the tissue projecting from the sporophyte.

Conducting Cells in Mosses

I got an email a while back asking about the leptom and hadrom in mosses (sometimes both of these terms are spelled with an added -e at the end). Admittedly I had not heard these two terms before, but I was pretty sure that they referred to the hydroids (water conducting cells) and leptoids (photoshythate/sugar conducting cells) in mosses. Yes, some bryophytes do have specialized cells for conducting either water or sugars through their plant body, however, the walls of these cells are not strengthened by the compound lignin, so they are not termed xylem and phloem.

I headed to my handy reference shelf to look up the definitions of these two terms and here is what I found about the water conducting cells of mosses.

The hadrom is a term for all the of hydroids together in a structure. In mosses hydroid cells are present in the peristomate mosses (those with teeth around the mouth of the capsule) which includes the Bryopsida, the crown group of mosses, and the Polytrichopsida, the hairy-capped mosses. Hydroids are lacking in some of the earliest diverging lineages: including Sphagnaceae, Andreaeaceae, and Andreaobryaceae.
(Paragraph Updated 16 April 2014:  An earlier version of this post incorrectly stated that hydroids are only present in the Bryopsida. However, in Ligrone et al 2000 they state that hydroids are present in the Bryidae. This older name for the group includes both the Bryopsida and the Polytrichopsida and thus has been updated in the paragraph above.)

The leptom (consisting of leptoids) is unique in mosses to the Dawsoniidae and Polytrichidae (the group of mosses that includes Polytrichum, the hairy capped mosses). Other groups of mosses have cells that could be termed 'conducting parenchyma cells', but they are not as specialized as leptoids. 

These terms (leptom and hadrom) were introduced by the German botanist Haberlandt in 1879, which is probably why I hadn't heard of them before.

If you are interested in reading more, this paper has a very thorough and readable discussion of water conducting cells in bryophytes, which I consulted for the above information on hydroids and leptoids.

R Ligrone, J G Duckett, and K S Renzaglia. 2000. Conducting tissues and phyletic relationships of bryophytes. Philos Trans R Soc Lond B Biol Sci. 355: 795–813. 

To give you a visual of these conducting cells, I remembered that I came across some during the course of my dissertation research. Below is a transverse section through the midrib of a gametophyte leaf of Funaria hygrometrica.

The cells with the thickest walls in the middle-center are stereids, which help to support the leaves. Directly above them are two cells that have a 'blown out' appearance. These cells do not have any cytoplasmic contents and have a very thin wall between them. I would interpret these cells as hydroids. Above and slightly to the right of the hydroids is a large cell with intact cellular contents and a large number of pores in one of the cell walls. Thus I think that this is a food conducting cell or conducting parenchyma cell. 

I have blown up the image and added some letters to help orient you to the larger image above. (Key: stereid = s, hydroid = h, food conducting cell = fcc)

It has been a while since I have looked at and interpreted electron micrographs. Well maybe not so long ago. I did a lot of that for my dissertation but the interpretation stage seems like, and was a couple of years ago. Interpreting this micrograph was super fun and tells me that I need to get back to the electron microscopy lab and generate some more images and data to interpret and think about!

Moss Meetings

Last week I was down in New York at two meetings focusing on Mosses. Yes I go to scientific conferences where everyone is studying bryophytes. Pretty nerdy, I know, but it is actually really fun to hang out with scientists who all share similar interests and to learn about the newest research coming out of laboratories from around the world. 

If you are interested in checking out the talks that were given you can download the brochure with all of the abstracts for each talk given at the meeting. (Abstracts program here) They are basically summaries of the questions asked and major findings of each presentation given at the meeting. They are not nearly as in-depth as listening to the presentation in person, but do give an overview of the topics we covered. 

And here we all are posing outside one of the research buildings at the New York Botanical Garden where the meeting was held.

June 2012 Desktop Calendar

This is an image pulled from my archives. A flashback from 2008. Shown here are some mosses growing in a raked rock garden at a temple in Japan. 

If you are interested in downloading this desktop calendar follow the instructions below. 

1 - Single click on the image to open it up in a new window. (If you use the image directly from the blog post you will loose a lot of resolution.)

2 - Right-click (or ctrl-click) on the image, and chose the option that says, "Set as Desktop Background" or "Use as Desktop Picture". The wording may vary.

3 - If the image does not fit your desktop neatly, you may have to adjust the image (Mac: System Preferences > Desktop > Screen Saver > Desktop; Windows: Control Panel > Display > Desktop) and choose "Fill screen" as the display mode of your background image.

Any issues or suggestions please let me know. These calendars are an experiment in-progress.

Mosses at Trout Brook Valley

I led a moss walk at the end of April at Trout Brook Valley, which is part of the Aspetuck Land Trust in southwestern Connecticut. Unfortunately we had a pretty dry April and the mosses were a little crispy. However, we did locate some that we lush and moist on this drippy rock wall. 

Here we are checking out some mosses growing on a rock. 

Hand-lenses in action!

Thanks to everyone who attended the walk and to Heather Williams Walklet for sending these photos.

The Map of Life. Mapping mosses next?

Have you heard about the Map of Life? They just released their first demo version of the mapping program. The program integrates data on species distributions from a number of sources, such as, point data from collection records, local inventories, and regional checklists. You can either look up a particular species and see where it lives or choose a location in the world and see a list of the species that occur there.   

Thus far they have included Birds, Freshwater fishes, Reptiles, Amphibians, and Mammals. I have suggested to one of my fellow UConn alums, Adam Wilson, who is working on the project, that mosses be added to the mapping list next. Mosses are listed in the Global Biodiversity Inventory Facility (Gbif), so the data is available to add them to this project, but I am guessing that I will have to wait a while until mosses are included. What group would you like to see added to the mapping next? 

Check out the Map of Life program here

Below is an example of the maps that are produced. They use Google Maps and can show multiple layers of distribution data from different sources. The maps are fully interactive and allow you to zoom in to a particular area of interest. I think that this is going to be a really great resource for scientists and amateur naturalists. Imagine going on travels or a collecting trip and being able to pull up a list of all the species in your area, and also a map of previous collection sites so that you can hunt for organisms. (This does assume that you have a fancy phone with web capabilities for the field and that you are not somewhere too remote for a signal.) However, I think that this would be a useful tool prior to heading into the field or for planning a collecting trip.

As an example, this is the distribution map from the smooth earthsnake that I posted about last week.

Some additional information

 - An article from Popular Science talking about the Map of Life.

 - An article in Trends in Ecology & Evolution about the project.

Spore Dispersal by Snakes

I tend to avoid snakes in life in general, but this snake is having a super cool interaction with a moss. If you look closely, it appears that this smooth earthsnake is covered in moss spores!

Close-up of the snake's head.

Close-up of the bright green spores coming out of the moss capsule. 

What do you think? I think that they look like spores on the snake. How long will they stick or how far can the snake go without them falling off? Easy to guess, hard to measure.  Probably a little ways, maybe further depending on how quickly they dry and the cover of plants the snake is crawling through. I think that spore dispersal by animals is a very interesting phenomenon and is under documented in the literature. Have a favorite spore dispersing creature or photos you would like to share?

Thanks to Tobias Landberg, a postdoctoral researcher at Murray State University in Kentucky, for taking and sending me these photos.

Moss Sperm Surviving Desiccation

When I think about moss reproduction, I usually think about the fact that mosses have flagellated sperm that require water to swim to the female archegonium that holds the egg. Researchers at Portland State University have been thinking about sperm survival when desiccated. I think that this is a really interesting question. Imagine that it rains and a moss sperm begins its journey swimming toward and egg. What happens if mid-travel the water dries up and the sperm is stranded? Can the sperm cell survive and resume its journey when it is wet again? 

In this study, the effects of desiccation on sperm cells were examined in three moss species.

Shortlidge, E. E., Rosenstiel, T. N. and Eppley, S. M. 2012. Tolerance to environmental desiccation in moss sperm. New Phytologist 194: 741–750.

They found that a fraction of the sperm were able to survive desiccation (e.g., Ceratodon purpureus, on average 17% survived) and the desiccation tolerance did not vary significantly among species. These results indicate the possibility of a sperm bank existing on the landscape. I have heard about a seed bank and a spore bank, but had not thought about a sperm bank before. I think that this is a pretty cool idea and as the authors mention has significant implications for understanding moss mating systems. That is just one finding from this paper. There is a lot more about desiccation tolerance, the effect of sucrose on sperm survival, and sperm variation. I highly recommend checking out this paper if you are interested in learning more. I think that it is good science and a well-written research article. Kudos to the authors. 

May 2012 Desktop Calendar

Well my hopes for April, when I said I was going to make some time for blog posting, were not realized. Not a single post. Except for the calendar. May will hopefully be better, thought starting off with a calendar post on day 11 is not the best start.

I have decided to blame the lack of April posts on an ongoing case of poison ivy and the delay in the calendar on graduation last weekend. May productivity here I come!

Below, on the calendar, is an unidentified Grimmiaceae from my collecting trip to Kansas and Missouri in March. This little tuft is going to remind me to get things done and to identify him/her by the end of the month. Maybe blog posting on monthly goals is good motivation?

If you are interested in downloading this desktop calendar follow the instructions below.

1 - Single click on the image to open it up in a new window. (If you use the image directly from the blog post you will loose a lot of resolution.)

2 - Right-click (or ctrl-click) on the image, and chose the option that says, "Set as Desktop Background" or "Use as Desktop Picture". The wording may vary.

3 - If the image does not fit your desktop neatly, you may have to adjust the image (Mac: System Preferences > Desktop > Screen Saver > Desktop; Windows: Control Panel > Display > Desktop) and choose "Fill screen" as the display mode of your background image.

Any issues or suggestions please let me know. These calendars are an experiment in-progress.

April 2012 Desktop Calendar

Below is an image of Physcomitrium hookerii from the collecting trip I made to Missouri and Kansas a couple of weeks back. I have some additional photos from my travels to post up. Maybe April will have a little more space for blog posting.

If you are interested in downloading this desktop calendar follow the instructions below.

1 - Single click on the image to open it up in a new window. (If you use the image directly from the blog post you will loose a lot of resolution.)

2 - Right-click (or ctrl-click) on the image, and chose the option that says, "Set as Desktop Background" or "Use as Desktop Picture". The wording may vary.

3 - If the image does not fit your desktop neatly, you may have to adjust the image (Mac: System Preferences > Desktop > Screen Saver > Desktop; Windows: Control Panel > Display > Desktop) and choose "Fill screen" as the display mode of your background image.

Any issues or suggestions please let me know. These calendars are an experiment in-progress.