botany - What factors affect the rate of transpiration in plant leaves?

I'm trying to get my head around factors which affect transpiration in leaves.

For example, how would applying petroleum jelly to the surface of plant leaves affect their rate of transpiration?

I get that it's basically going to decrease the trasnpiration rate because the stomata will be covered, but I'm not sure about these parts:

• How would it affect the rate of transpiration if only the top surface was covered?


• How would it affect the rate of transpiration if only the bottom surface was covered?

Also, I think I'm right in saying that increasing wind / applying a fan to plant leaves will increase the transpiration rate, but why?

Robotic surgery for treating cancer?

I'm assuming you are not talking about a single solid tumor, but rather one where the tumor is loose and is distributed throughout the tissue, or has metastasized

I guess the answer is you could, but it would be one amazing machine. This robot would have to examine each individual cell and destroy it based on what you could sense about the surface properties. Identifying cancer cells on the basis of the proteins and glycosyl (carbohydrate) molecules on the cell surface is not embodied in a reliable way in a touch sensor. Cancer can manifest lots of such patterns and it could quite easily be that if you looked at healthy cells, they look very similar. Cancer cells don't have an obvious sign they are always holding out saying 'im cancer'...

Then there is the structure of tumors. For instance glioma is one of the most difficult brain cancers you can have. The glioma cells push out axons - they can be quite long. Its hard to imagine a robot that could find that in a brain without tearing up all the neural connections. In prostate cancers - one of the most common cancers in men, the cells are embedded in the tissue surrounded by necessary and healthy cells.

This is why chemicals and nano structures are the most commonly pursued means of combating cancer; they can enter into cells that are embedded in solid organs. Differentiating the cancer cells from other sorts of cells in vivo is a pretty hard problem - some antibodies are given as a possible help there, but they are not reliable.

This blog post is a pretty up to date summary of where we are

http://www.sciencebasedmedicine.org/index.php/personalized-medicine-vs-evolution/

evolution - Productive turnover and generations in the fruit fly

What do you mean by you couldn't find anything on the internet? Drosophila generation time is explained here?

Your other question is a bit off-topic here but I'll give all advice I have heard myself:

You can leave out a banana skin and catch some fruit flies, then do the experiment in your kitchen :) Joke aside, unless you perform the experiment independently it will probably take a long time and it's well possible that you won't be able to do it at all (unless you become some famous scientist). I'm not familiar with the experiments you mention, but if you require equipment and/or funding, you will need a qualification and/or a good explanation why people should give you money or let you use their equipment for this experiment.

I don't know what stage of education you are at, but it sounds like you are still at school ("when I'm older")? Most countries have some schemes where students (below uni) can apply for young researcher kind of things, so you could try and google that. Apart from that, the best bet is probably to try and get into a uni with good facilities and research programmes for their students. What you study shouldn't matter so much as long as it's science.

In response to Marta's commment: if you understand the experiment and you think you can gather everything they used at home, nothing speaks against just doing it on your own. Just make sure you don't let those flies swarm your house ;)

molecular biology - How to find ion/water channel related genes

We now have a collection of transcripts at hand. We would like to investigate some particular ones, which are ion/water channel related. How to perform this? Could anybody point out how to find the annotated genes those are ion/water channel related? If there are some places particularly for fish, that would be perfect. Thanks.

botany - How long will a vegetable live for after being harvested?

The short answer is that as long as the vegetable/fruit is fresh looking - i.e. the cells have not disintegrated - they will be respiring, many cells will be functioning quite normally, and the plant is still technically alive. In cases where the part of the plant we treat as a vegetable is a part intended for reproduction (e.g. a seed, or a tuber like a potato) the plant will keep growing.

The point at which the plant dies is not clearly defined like it is in animals, but generally if you can still eat it, it's still alive.

Death in plants is quite different from that in animals - we refer to it as senescence. The key difference is that it happens to tissues and organs which can die and separate from the organism. Individual leaves can die without the plant's health being affected. Once this has happened to all the parts, the organism is considered dead, but if there is any respiring tissue left, it's still alive.

assay development - Providing small molecules to cells on a filter plate

Lets imagine that I have mammalian cells that I've immobilized on a filter. Now I want to keep providing small molecules to these immobilized cells without resolubilizing the cells.

The caveat is that I would like to do so without fixing the cells or waiting for them to adhere to the filter. The small molecules are small enough to diffuse through the filter.

evolution - Why do we grow so much hair on our heads compared to our bodies?

I've been wondering about head hair, facial hair in particular. Human males can grow very extensive beards should they choose to not shave - however you do not really see this in our chimpanzee cousins! Yes, they have little pseudo-beards, but the difference being that they do not shave, that is just the length they reach. Whereas in humans we can grow to our hearts content (*this may not be the case, see this question).

I can't really see why this would have been selected, unless it's simply that (evolutionarily speaking) women like men with long beards?

So my question is: why can humans perpetually grow head hair, yet we have lost the majority of our body hair, in comparison to chimpanzees and other ape family members?

microbiology - Aren't antibiotic resistant probiotics dangerous?

Usually, resistance genes are located on plasmids---additional DNA rings in the bacterium that are part of the genome. These plasmids cause their own exchange with other bacteria, even from other species.

B. clausii, the probiotics organism in question here, appears to be special, though, in that it has no plasmids. His resistance genes come with the primary ring-shaped genome and should not be transferred via plasmid exchange to other bacteria. This doesn't rule out other means of gene transfer like phages or conjugation, however. In one study, it was unsuccessfully tried to transfer a macrolide resistance gene to other bacteria. They conclude

A potential hazard is transfer of resistance to microorganisms
pathogenic for humans. The risk that this event will occur and the
consequences in terms of morbidity and mortality have not been
evaluated. Parameters required for risk assessment include studies on
the nature and mobility of the resistance genes of probiotics.

The only other paper on a B.clausii resistance gene didn't look at its transferability. That clearly shows we don't know enough.

B. Bozdogan, S. Galopin, R. Leclercq: Characterization of a new erm-related macrolide resistance gene present in probiotic strains of Bacillus clausii. In: Applied and environmental microbiology. Band 70, Nummer 1, Januar 2004, S. 280–284, {{ISSN|0099-2240}}. PMID 14711653. PMC 321311.