We are indebted to Xuefei Yang, Sabine Both, Lin Chen and Kaitian Wang for coordinating the fieldwork and establishing the BEF-China experiment. We are also grateful to the whole BEF-China research group for their general support. BEF-China is mainly funded by the German Research Foundation (DFG FOR 891/1 and 2) and funding for this particular project was provided by the German Research Foundation to H.B. (DFG BR 1698/9-2). We are also thankful for the travel grants and summer schools financed by the Sino-German Centre for Research Promotion in Beijing (GZ 524, 592, 698, 699 and 785). In addition we would like to thank David Eichenberg, Michael Staab, Katja Grotius, Silvana Tornack, Lin Chen, and Shouren Zhang for their support in the field and in the lab.

1. Stomatal Conductance
<ol>
	<li>Measurements of stomatal conductance 
	NOTE: The authors made use of a simple type of steady state porometer (Decagon SC1). The porometer&#8217;s design has the advantage of small size, intuitive manual operation and high reliability. When measuring stomatal conductance in the field, make sure to minimize the distance between measured individuals for a repeated measurement cycle to be the most efficient possible.</li>
	<li>Choose leaves of different species and individuals according to a reproducible pattern (same height, same exposure, same position within the plant, if possible only from the same node, and only from one category; sun or shade leaves, etc.).
	<ol>
		<li>Only measure leaves in healthy, non-damaged and fully developed condition. Mark the leaves on the individuals (e.g., with cable ties or color tape), to ensure that the repeated measurements are done on the same leaf. 
		NOTE: Measurements of stomatal conductance should be made only on leaf surface whilst avoiding the midrib and strong leaf veins.</li>
		<li>Start measurements in the early morning hours before sunrise taking five to ten repeated measurements until stomatal conductance values shows a clear decline at noon. 
		NOTE: A daily course of measurements will deliver good data for analyzing the relationships between vpd and stomatal conductance.</li>
	</ol>
	</li>
	<li>Vpd measurements
	<ol>
		<li>With each gS measurement, record temperature and relative humidity preferably with portable loggers to directly measure the conditions at the position of the same leaf. For calculating the vapor pressure deficit use the August-Roche Magnus formula15.</li>
	</ol>
	</li>
</ol>
<img alt="Equation 1" fo:content-width="3in" src="/files/ftp_upload/52738/52738eq1.jpg" width="300" />
es=saturation water vapor pressure [hPa]
T=temperature [&#176;C]
<ol start="4">
	<li>Model gS - vpd response
	<ol>
		<li>Now plot species-wise all gS data against vpd, combining all daily courses of individual leaves into one analysis per species. Extract the maximum value observed from the stomatal conductance data by searching for the maximum value. To scale the model for species-wise comparability, divide the observed values through the maximum value observed for that species (gS/gSMAX).</li>
		<li>For each species, regress the logits of gS (gS/gSMAX) to vpd and the quadratic term of vpd using a generalized linear model with a binomial error distribution (a, b and c represent regression parameters):</li>
	</ol>
	</li>
</ol>
<img alt="Equation 2" src="/files/ftp_upload/52738/52738eq2.jpg" width="300" />
<img alt="Figure 1" src="/files/ftp_upload/52738/52738fig1highres.jpg" width="700" /> 
Figure 1. Example of the plotted values and the fitted model for gS - vpd. Stomatal conductance plotted as a function of vapor pressure deficit for the species Liquidambar formosana. Empty dots represent the observed values. (A) Maximum stomatal conductance, the vpd at maximum stomatal conductance and mean stomatal conductance was extracted from the absolute thus non-scaled stomatal conductance (gS) data. (B) Scaled stomatal conductance data (gS/gSMAX) were plotted to extract the relative parameters (shown as filled dots) 20. Re-print with permission from20. <a href="https://www.jove.com/files/ftp_upload/52738/52738fig1highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/52738/52738fig2highres.jpg" width="400" /> 
Figure 2. All fitted models for all species. Model graphs for the stomatal conductance data to vpd regression for all species. Evergreen species are represented by black lines, deciduous species by red lines 20. Re-print with permission from20.
NOTE: Using the logits instead of regressing gS directly to vpd, leads to the point that modeled maximum values do not exceed gSMAX and that gS approaches 0 at high vpd.
<ol start="5">
	<li>Extract parameter of stomatal regulation for every species
	<ol>
		<li>Calculate absolute modeled gSMAX values (MaxFit in Figure&#160;1B). To do this, calculate the vpd at maximum stomatal conductance from setting the first derivative of 1.4.2 to zero, which gives vpdgsMaxFit = -b/2a. Insert vpdgsMaxFit into the formula of 1.4.2 and raise to the power of e to obtain MaxFit. Calculate the mean of all conductance measurements per species (see Figure 1A). 
		NOTE: Use statistical software R (http://www.r-project.org).</li>
		<li>To calculate relative values, from the scaled model (gS/gSMAX), extract stomatal conductance and vpd values for the following two points: (1) stomatal conductance and vpd at the maximum of the model (MaxFit) and (2) vpd at the second point of inflection of the curve (see Figure 1B). Multiply these values by gSMAX to obtain absolute gS values for these points. See Figure 2 for a complete overlay of the single models of all 39 species analyzed.</li>
	</ol>
	</li>
</ol>
2. Measurements of Stomatal Traits
<ol>
	<li>Take samples preferably from exactly the same leaves that have been used for the measurements of stomatal conductance. If this is not possible, apply the same selection procedure that was applied to choose the leaves for the stomatal conductance measurements, preferably on the same individuals.</li>
	<li>Apply a thin layer of colorless, quickly drying nail polish (test different makes, some are more suitable than others) to a fresh sample. If the samples cannot be processed immediately, store them in 70% alcohol. After the nail polish has dried out, gently peel the impression of from the leaf and proceed for the microscopic analysis, as with a normal leaf sample. &#160; 
	NOTE: In the case of leaves with high trichome density a preceding step of applying sodium hydroxide or a 1:1 solution of acetic acid and oxygen peroxide can lead to better results.</li>
	<li>Optical microscope analytics
	<ol>
		<li>Connect a camera to an optical microscope capable of magnifications between 40X to 400X. After the camera is connected to the microscope, match the pictures taken to the optical magnification and resolution of the picture, e.g., with the help of a scale.</li>
		<li>Employing open source image processing software like ImageJ 16 analyze these pictures.
		<ol>
			<li>Draw a shape with the shape tool from the image analysis tool on the image in an area with no dirt, thumb prints, damaged areas, or large leaf veins. Count stomata in this area and in total of at least 50,000 &#181;m2 per sample.</li>
			<li>Measure stomatal guard cell length and pore length. Calculate the number of stomata per mm2. Calculate stomatal index as the ratio of stomatal density to epidermal cell number per mm2.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
3. Assessment of Leaf Vein Traits
NOTE: For the assessment of leaf vein traits, a modified a protocol from Sack &#38; Scoffoni 17 was employed.
<ol>
	<li>Sample preparation 
	NOTE: To optimize the visibility of the leaf veins, the leaves are first bleached and then stained with safranine and malachite green.
	<ol>
		<li>To bleach the leaves, leave them at least 72 hr in 50% solution of decolorizer (test different makes, again some might work better). Alternatively, use 5% NaOH solution or 10% KOH solution or 25% H2O2 solution.</li>
		<li>Heat the solution up to 30&#176; C or combine the different solutions from step 3.1.1 for better effects. Rinse several times in water afterwards. Adapt the bleaching process for the specific species, depending on their leaf characteristics. 
		NOTE: Thicker leaves may need longer periods of solution bath and or the more aggressive solutions. Thinner and more tender leaves may be bleached to a satisfactorily degree in less than 72 hr.</li>
		<li>To color the leaves place them in 100% ethanol. Color them for 2 &#8211; 30 min in 1% safranine solution. To enhance coloring, add an additional treatment with 1% malachite green solution only for several seconds. Adapt the protocol to every species in terms of timing and intensity to achieve optimal results. Rinse several times in water afterwards. If the leaves are to deeply stained, some time in ethanol or decolorizer may help.</li>
	</ol>
	</li>
	<li>Sample analysis
	<ol>
		<li>Scan the leaves with a backlight scanner at a resolution of ca. 1,200 dpi. Match the scans taken to the resolution of the picture, e.g., with the help of a scale, to ensure that pixel length can be traced back to absolute length measures of the scanned leaf.</li>
		<li>Measure area, circumference, length and width of the leaves. Calculate several indices, e.g., length/width and circumference2/area. Cut a 1 by 1 cm rectangle out of the middle of the picture. Measure diameter of the veins of first and second order (do not include the main middle vein). Measure the length of all veins of first order in this quadrat (vein density).</li>
	</ol>
	</li>
</ol>
4. Assessment of Other Leaf Traits
NOTE: Asses typical leaf traits such as specific leaf area (SLA), leaf dry matter content (LDMC), leaf area, element contents, leaf habit, leaf pinnation, leaf compound type, leaf margin type etc. following established protocols 18,19.
<ol>
	<li>Observational leaf traits
	<ol>
		<li>Assess leaf pinnation, leaf compound type, leaf margin type and the presence of extrafloral nectaries18,19 through observation in the field.</li>
	</ol>
	</li>
	<li>Analytical leaf traits
	<ol>
		<li>Collect fresh leaf samples, preferably on the same individuals as used for the other measurements, for the determination of specific leaf area (SLA), leaf area and leaf dry matter content (LDMC) 18,19. After 48 hr in the drying oven at 80 &#176;C, measure element contents and ratios, preferably on the same leaves.</li>
	</ol>
	</li>
</ol>

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The authors have nothing to disclose.

The parameters of stomatal regulation extracted by the method presented in this paper underline the importance of stomatal traits, such as stomata density and stomata index. These novel relationships demonstrate the potential of linking parameters from physiological models to morphological, anatomical and chemical leaf traits 20. Compared to other methods, the present approach bears the advantage of capturing a unique and unequivocal vpd value at which stomatal conductance is down-regulated to half of the modeled gs maximum.
Of all steps outlined in the protocol the most critical ones are the measurements of stomatal conductance. Due to the multifactorial regulation of stomatal conductance ambient weather conditions have a strong influence on gS. Stomatal conductance measurements at high relative humidity and low light intensity may be unreliable 21-23. With respect to morphological and anatomical traits, the protocol should always be adapted to the target species included in the study. In particular in the vein density analysis, the duration of bleaching and staining of leaves should be varied, depending on leaf structure and toughness. Potential limitations of the method include species, for which measurements of stomatal conductance are impossible or complicated and prone to error owing to extraordinary leaf forms. This may include conifers and grasses with very narrow leaf blades.
Our results partly confirm the first hypothesis of a link between stomatal conductance parameters and leaf traits of the leaf economics spectrum (LES), which corresponds to several other studies. For example, Poorter and Bongers (2006)24 reported a close link between gS and traits represented by the LES, e.g., with gS decreasing with increasing leaf lifespan. Accordingly, Schulze et al. (1994) 1 demonstrated clear links between leaf nitrogen content and gSMAX. Similarly, Juhrbandt et al. (2004) 25 found significant relationships between gSMAX and leaf area and leaf nitrogen content.
Our second hypothesis of clear differences with regard to leaf habit could not be confirmed. The high variation in the measured parameters and traits within evergreen and deciduous leaf habit indicate that leaf habit is not a good descriptor of the LES. Brodribb and Holbrook (2005) 26 discussed that leaf habit and leaf physiological strategies may not be inevitably connected since broad trait variation is common in all types of leaf habit.
The approach may be extended to traits and physiological characteristics of plant organs other than leaves, for example to traits related to xylem hydraulics such as specific xylem hydraulic conductivity and microscopy wood traits 27. Similarly, other types of leaf traits as derived from microscopy such as palisade parenchyma structure and epicuticular wax layer structure could be included 28.
In summary, this study confirmed the close connection between the LES and stomatal regulation. In addition, the method presented here revealed facets of stomatal regulation patterns that are not related to the LES. Especially specific leaf traits such as stomata size, density and index as well as vein length deserve future attention in functional plant studies.

To advance the functional understanding of plant leaves, many recent studies have attempted to relate morphological, anatomical and chemical leaf traits to physiological responses, such as leaf stomatal conductance (gS) 1-4. In addition, to leaf traits, stomatal conductance is strongly affected by environmental conditions, such as photosynthetically active photon flux density, air temperature and vpd 5. Various ways have been proposed to model gs - vpd curves6-8 which are mainly based on linear regression of gs on vpd 6. In contrast, the model presented in this study regresses the logits of relative stomatal conductance (i.e., the ratio of gS to maximum stomatal conductance gSMAX) on vpd and accounts for the non-linearity by adding vpd as a quadratic regressor term.
Compared to other models, the new model allows for deriving parameters that describe the vpd at which gS is down-regulated under water shortage. Similarly, the vpd is obtained at which gS is maximal. As such physiological parameters can be expected to be tightly linked to carbon assimilation 9,10 a close link between these model parameters and the key leaf traits to nutrient and resource allocation as reflected in the LES should be expected 3,11. In consequence, there should be also a tight relationship between strategies of stomatal regulation with LES traits. Such a relationship is expected in particular for leaf habit (evergreen versus deciduous) as leaf habit is both correlated with the LES and with water use efficiency12,13. Evergreen species tend to grow slower, but are more efficient in environments poor in nutrients 14. Thus, leaf habit should translate into differing stomatal regulation patterns, with a more conservative water use strategy than deciduous species.
Comparing a large set of broad-leaved tree species in a common garden situation, the following hypotheses were tested: 1) Model parameters from gS - vpd models are connected to leaf traits related to the leaf economics spectrum. 2) Evergreen species have lower mean gS and gSMAX values than deciduous species.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>SC 1 Porometer</td>
			<td>Decagon</td>
			<td>NA</td>
			<td>Any other porometer is suitable</td>
		</tr>
		<tr>
			<td>Cable ties to mark leaves</td>
			<td>NA</td>
			<td>NA</td>
			<td>NA</td>
		</tr>
		<tr>
			<td>Plastic sample bags</td>
			<td>NA</td>
			<td>NA</td>
			<td>NA</td>
		</tr>
		<tr>
			<td>Paper sample bags</td>
			<td>NA</td>
			<td>NA</td>
			<td>NA</td>
		</tr>
		<tr>
			<td>Hygrometer</td>
			<td>Trotec</td>
			<td>NA</td>
			<td>Any other is suitable</td>
		</tr>
		<tr>
			<td>Nail polish</td>
			<td>NA</td>
			<td>NA</td>
			<td>NA</td>
		</tr>
		<tr>
			<td>Axioskop 2 plus</td>
			<td>Zeiss</td>
			<td>NA</td>
			<td>Any other is suitable</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>NA</td>
			<td>NA</td>
			<td>NA</td>
		</tr>
		<tr>
			<td>Bleach</td>
			<td>NA</td>
			<td>NA</td>
			<td>NA</td>
		</tr>
		<tr>
			<td>5% NaOH</td>
			<td>NA</td>
			<td>NA</td>
			<td>NA</td>
		</tr>
		<tr>
			<td>10% KOH</td>
			<td>NA</td>
			<td>NA</td>
			<td>NA</td>
		</tr>
		<tr>
			<td>25% H2O2</td>
			<td>NA</td>
			<td>NA</td>
			<td>NA</td>
		</tr>
		<tr>
			<td>Malachite green</td>
			<td>NA</td>
			<td>NA</td>
			<td>NA</td>
		</tr>
		<tr>
			<td>Safranine</td>
			<td>NA</td>
			<td>NA</td>
			<td>NA</td>
		</tr>
	</tbody>
</table>

relating stomatal conductance to leaf functional traits

Leaf functional traits are important because they reflect physiological functions, such as transpiration and carbon assimilation. In particular, morphological leaf traits have the potential to summarize plants strategies in terms of water use efficiency, growth pattern and nutrient use. The leaf economics spectrum (LES) is a recognized framework in functional plant ecology and reflects a gradient of increasing specific leaf area (SLA), leaf nitrogen, phosphorus and cation content, and decreasing leaf dry matter content (LDMC) and carbon nitrogen ratio (CN). The LES describes different strategies ranging from that of short-lived leaves with high photosynthetic capacity per leaf mass to long-lived leaves with low mass-based carbon assimilation rates. However, traits that are not included in the LES might provide additional information on the species&#39; physiology, such as those related to stomatal control. Protocols are presented for a wide range of leaf functional traits, including traits of the LES, but also traits that are independent of the LES. In particular, a new method is introduced that relates the plants&#8217; regulatory behavior in stomatal conductance to vapor pressure deficit. The resulting parameters of stomatal regulation can then be compared to the LES and other plant functional traits. The results show that functional leaf traits of the LES were also valid predictors for the parameters of stomatal regulation. For example, leaf carbon concentration was positively related to the vapor pressure deficit (vpd) at the point of inflection and the maximum of the conductance-vpd curve. However, traits that are not included in the LES added information in explaining parameters of stomatal control: the vpd at the point of inflection of the conductance-vpd curve was lower for species with higher stomatal density and higher stomatal index. Overall, stomata and vein traits were more powerful predictors for explaining stomatal regulation than traits used in the LES.

Many parameters of stomatal conductance and stomatal regulation were found to be related to morphological, anatomical and chemical leaf traits. In the following, the focus will be on the links to vpd at the point of inflection, which decreased with stomatal density (p=0.04) and stomatal index (p=0.03) and increased with leaf carbon content (p=0.02, See Figure 3). The results show that with decreasing vpd at the point of inflection there was a decrease in stomatal density and stomatal index. In contrast, no parameter of stomatal conductance showed a clear relationship to leaf habit. The high variation within the two groups of leaf habit shows that different regulatory mechanisms exist both within the group of evergreen and deciduous leaf habits.

<img alt="Figure 3" src="/files/ftp_upload/52738/52738fig3highres.jpg" width="700" /> 
Figure 3. Result figure for the links between patterns of stomatal conductance regulation and leaf traits. Vapor pressure deficit (vpd) at the point of inflection of the gS - vpd curve (VpdPoi) as a function of (A) stomata density, (B) stomata index, and (C) leaf carbon content 20. Re-print with permission from20. <a href="https://www.jove.com/files/ftp_upload/52738/52738fig3highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Relating Stomatal Conductance to Leaf Functional Traits at JoVE.com

Relating Stomatal Conductance to Leaf Functional Traits

Unraveling how physiology and morphology are linked allows a deeper understanding of mechanistic functioning of plant leaves. We present both a procedure to derive parameters of stomatal regulation from stomatal conductance measurements and correlations with traditional functional leaf traits.

Leaf functional traits are important because they reflect physiological functions, such as transpiration and carbon assimilation. In particular, ...

relating-stomatal-conductance-to-leaf-functional-traits

Research

JoVE Journal

Biology

19.0K Views.  Martin-Luther-University Halle-Wittenberg. Unraveling how physiology and morphology are linked allows a deeper understanding of mechanistic functioning of plant leaves. We present both a procedure to derive parameters of stomatal regulation from stomatal conductance measurements and correlations with traditional functional leaf traits.

Video: Relating Stomatal Conductance to Leaf Functional Traits

Light/dark Transition Test for Mice

Although all of the mouse genome sequences have been determined, we do not yet know the functions of most of these genes. Gene-targeting techniques, however, can be used to delete or manipulate a specific gene in mice. The influence of a given gene on a specific behavior can then be determined by conducting behavioral analyses of the mutant mice. As a test for behavioral phenotyping of mutant mice, the light/dark transition test is one of the most widely used tests to measure anxiety-like behavior in mice. The test is based on the natural aversion of mice to brightly illuminated areas and on their spontaneous exploratory behavior in novel environments. The test is sensitive to anxiolytic drug treatment. The apparatus consists of a dark chamber and a brightly illuminated chamber. Mice are allowed to move freely between the two chambers. The number of entries into the bright chamber and the duration of time spent there are indices of bright-space anxiety in mice. To obtain phenotyping results of a strain of mutant mice that can be readily reproduced and compared with those of other mutants, the behavioral test methods should be as identical as possible between laboratories. The procedural differences that exist between laboratories, however, make it difficult to replicate or compare the results among laboratories. Here, we present our protocol for the light/dark transition test as a movie so that the details of the protocol can be demonstrated. In our laboratory, we have assessed more than 60 strains of mutant mice using the protocol shown in the movie. Those data will be disclosed as a part of a public database that we are now constructing.

Visualization of the protocol will facilitate understanding of the details of the entire experimental procedure, allowing for standardization of the protocols used across laboratories and comparisons of the behavioral phenotypes of various strains of mutant mice assessed using this test.

The light/dark transition test is one of the most widely used tests to measure anxiety-like behavior in mice. Here, we present a movie that shows detailed procedures on how we conduct the test.

Although all of the mouse genome sequences have been determined, we do not yet know the functions of most of these genes. Gene-targeting techniques, ...

Crystallizing Membrane Proteins for Structure Determination using Lipidic Mesophases

A detailed protocol for crystallizing membrane proteins by using lipidic mesophases is described. This method has variously been referred to as the lipidic cubic phase or in meso method. The method has been shown to be quite versatile in that it has been used to solve X-ray crystallographic structures of prokaryotic and eukaryotic proteins, proteins that are monomeric, homo- and hetero-multimeric, chromophore-containing and chromophore-free, and alpha-helical and beta-barrel proteins. Recent successes using in meso crystallization are the human engineered beta2-adrenergic and adenosine A2a G protein-coupled receptors. Protocols are presented for reconstituting the membrane protein into the monoolein-based mesophase, and for setting up crystallizations in the manual mode. Additional steps in the overall process, such as crystal harvesting, are to be addressed in future video articles. The time required to prepare the protein-loaded mesophase and to set up a crystallization plate manually is about one hour.

Herein is described the procedure implemented in the Caffrey Membrane Structural and Functional Biology Group to set up manually crystallization trials of membrane proteins in lipidic mesophases.

A detailed protocol for crystallizing membrane proteins by using lipidic mesophases is described. This method has variously been referred to as the ...

A Reverse Genetic Approach to Test Functional Redundancy During Embryogenesis

Gene function during embryogenesis is typically defined by loss-of-function experiments, for example by targeted mutagenesis (knockout) in the mouse. In the zebrafish model, effective reverse genetic techniques have been developed using microinjection of gene-specific antisense morpholinos. Morpholinos target an mRNA through specific base-pairing and block gene function transiently by inhibiting translation or splicing for several days during embryogenesis (knockdown). However, in vertebrates such as mouse or zebrafish, some gene functions can be obscured by these approaches due to the presence of another gene that compensates for the loss. This is especially true for gene families containing sister genes that are co-expressed in the same developing tissues. In zebrafish, functional compensation can be tested in a relatively high-throughput manner, by co-injection of morpholinos that target knockdown of both genes simultaneously. Likewise, using morpholinos, a genetic interaction between any two genes can be demonstrated by knockdown of both genes together at sub-threshold levels. For example, morpholinos can be titrated such that neither individual knockdown generates a phenotype. If, under these conditions, co-injection of both morpholinos causes a phenotype, a genetic interaction is shown. Here we demonstrate how to show functional redundancy in the context of two related GATA transcription factors. GATA factors are essential for specification of cardiac progenitors, but this is revealed only by the loss of both Gata5 and Gata6. We show how to carry out microinjection experiments, validate the morpholinos, and evaluate the compensated phenotype for cardiogenesis.

Gene function can be obscured in loss-of-function experiments if there is compensation by another gene. The zebrafish model provides a relatively high-throughput means to reveal such functional redundancy in living embryos.

Gene function during embryogenesis is typically defined by loss-of-function experiments, for example by targeted mutagenesis (knockout) in the mouse. In ...

Expression and Purification of the Cystic Fibrosis Transmembrane Conductance Regulator Protein in Saccharomyces cerevisiae

The cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel, that when mutated, can give rise to cystic fibrosis in humans.There is therefore considerable interest in this protein, but efforts to study its structure and activity have been hampered by the difficulty of expressing and purifying sufficient amounts of the protein1-3. Like many 'difficult' eukaryotic membrane proteins, expression in a fast-growing organism is desirable, but challenging, and in the yeast S. cerevisiae, so far low amounts were obtained and rapid degradation of the recombinant protein was observed 4-9. Proteins involved in the processing of recombinant CFTR in yeast have been described6-9 .In this report we describe a methodology for expression of CFTR in yeast and its purification in significant amounts. The protocol describes how the earlier proteolysis problems can be overcome and how expression levels of CFTR can be greatly improved by modifying the cell growth conditions and by controlling the induction conditions, in particular the time period prior to cell harvesting. The reagants associated with this protocol (murine CFTR-expressing yeast cells or yeast plasmids) will be distributed via the US Cystic Fibrosis Foundation, which has sponsored the research. An article describing the design and synthesis of the CFTR construct employed in this report will be published separately (Urbatsch, I.; Thibodeau, P. et al., unpublished). In this article we will explain our method beginning with the transformation of the yeast cells with the CFTR construct - containing yeast plasmid (Fig. 1). The construct has a green fluorescent protein (GFP) sequence fused to CFTR at its C-terminus and follows the system developed by Drew et al. (2008)10. The GFP allows the expression and purification of CFTR to be followed relatively easily. The JoVE visualized protocol finishes after the preparation of microsomes from the yeast cells, although we include some suggestions for purification of the protein from the microsomes. Readers may wish to add their own modifications to the microsome purification procedure, dependent on the final experiments to be carried out with the protein and the local equipment available to them. The yeast-expressed CFTR protein can be partially purified using metal ion affinity chromatography, using an intrinsic polyhistidine purification tag. Subsequent size-exclusion chromatography yields a protein that appears to be &gt;90% pure, as judged by SDS-PAGE and Coomassie-staining of the gel.

Expression and Purification of the Cystic Fibrosis Transmembrane Conductance Regulator Protein in Saccharomyces cerevisiae

Attempts to express the cystic fibrosis transmembrane conductance regulator (CFTR) in Saccharomyces cerevisiae have, until now, yielded relatively low amounts of protein. This protocol and the associated reagents distributed via the Cystic Fibrosis Foundation should allow the preparation of milligram amounts of this 'difficult' eukaryotic membrane protein.

The  cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride  channel, that when mutated, can give rise to cystic fibrosis in  ...

Measurement of Leaf Hydraulic Conductance and Stomatal Conductance and Their Responses to Irradiance and Dehydration Using the Evaporative Flux Method (EFM)

Water is a key resource, and the plant water transport system sets limits on maximum growth and drought tolerance. When plants open their stomata to achieve a high stomatal conductance (gs) to capture CO2 for photosynthesis, water is lost by transpiration1,2. Water evaporating from the airspaces is replaced from cell walls, in turn drawing water from the xylem of leaf veins, in turn drawing from xylem in the stems and roots. As water is pulled through the system, it experiences hydraulic resistance, creating tension throughout the system and a low leaf water potential (&Psi;leaf). The leaf itself is a critical bottleneck in the whole plant system, accounting for on average 30% of the plant hydraulic resistance3. Leaf hydraulic conductance (Kleaf = 1/ leaf hydraulic resistance) is the ratio of the water flow rate to the water potential gradient across the leaf, and summarizes the behavior of a complex system: water moves through the petiole and through several orders of veins, exits into the bundle sheath and passes through or around mesophyll cells before evaporating into the airspace and being transpired from the stomata. Kleaf is of strong interest as an important physiological trait to compare species, quantifying the effectiveness of the leaf structure and physiology for water transport, and a key variable to investigate for its relationship to variation in structure (e.g., in leaf venation architecture) and its impacts on photosynthetic gas exchange. Further, Kleaf responds strongly to the internal and external leaf environment3. Kleaf can increase dramatically with irradiance apparently due to changes in the expression and activation of aquaporins, the proteins involved in water transport through membranes4, and Kleaf declines strongly during drought, due to cavitation and/or collapse of xylem conduits, and/or loss of permeability in the extra-xylem tissues due to mesophyll and bundle sheath cell shrinkage or aquaporin deactivation5-10. Because Kleaf can constrain gs and photosynthetic rate across species in well watered conditions and during drought, and thus limit whole-plant performance they may possibly determine species distributions especially as droughts increase in frequency and severity11-14.
We present a simple method for simultaneous determination of Kleaf and gs on excised leaves. A transpiring leaf is connected by its petiole to tubing running to a water source on a balance. The loss of water from the balance is recorded to calculate the flow rate through the leaf. When steady state transpiration (E, mmol &bull; m-2 &bull; s-1) is reached, gs is determined by dividing by vapor pressure deficit, and Kleaf by dividing by the water potential driving force determined using a pressure chamber (Kleaf= E /- &Delta;&psi;leaf, MPa)15.
This method can be used to assess Kleaf responses to different irradiances and the vulnerability of Kleaf to dehydration14,16,17.

Measurement of Leaf Hydraulic Conductance and Stomatal Conductance and Their Responses to Irradiance and Dehydration Using the Evaporative Flux Method EFM

We describe a relatively rapid (30 min) and realistic method for simultaneously measurement of leaf hydraulic conductance (Kleaf) and stomatal conductance (gs) for transpiring excised leaves. The method can be modified to measure the light and dehydration responses of Kleaf and gs.

Water is a key resource, and the plant water transport system sets limits on maximum growth and drought tolerance. When plants open their stomata to ...

LeafJ: An ImageJ Plugin for Semi-automated Leaf Shape Measurement

High throughput phenotyping (phenomics) is a powerful tool for linking genes to their functions (see review1 and recent examples2-4). Leaves are the primary photosynthetic organ, and their size and shape vary developmentally and environmentally within a plant. For these reasons studies on leaf morphology require measurement of multiple parameters from numerous leaves, which is best done by semi-automated phenomics tools5,6. Canopy shade is an important environmental cue that affects plant architecture and life history; the suite of responses is collectively called the shade avoidance syndrome (SAS)7. Among SAS responses, shade induced leaf petiole elongation and changes in blade area are particularly useful as indices8. To date, leaf shape programs (e.g. SHAPE9, LAMINA10, LeafAnalyzer11, LEAFPROCESSOR12) can measure leaf outlines and categorize leaf shapes, but can not output petiole length. Lack of large-scale measurement systems of leaf petioles has inhibited phenomics approaches to SAS research. In this paper, we describe a newly developed ImageJ plugin, called LeafJ, which can rapidly measure petiole length and leaf blade parameters of the model plant Arabidopsis thaliana. For the occasional leaf that required manual correction of the petiole/leaf blade boundary we used a touch-screen tablet. Further, leaf cell shape and leaf cell numbers are important determinants of leaf size13. Separate from LeafJ we also present a protocol for using a touch-screen tablet for measuring cell shape, area, and size. Our leaf trait measurement system is not limited to shade-avoidance research and will accelerate leaf phenotyping of many mutants and screening plants by leaf phenotyping.

Demonstration of key methods for high throughput leaf measurements. These methods can be used to accelerate leaf phenotyping when studying many plant mutants or otherwise screening plants by leaf phenotype.

High throughput phenotyping (phenomics) is a powerful tool for linking genes to their functions (see review1 and recent examples2-4). Leaves are the ...

Purification of the Cystic Fibrosis Transmembrane Conductance Regulator Protein Expressed in Saccharomyces cerevisiae

Defects in the cystic fibrosis transmembrane conductance regulator (CFTR) protein cause cystic fibrosis (CF), an autosomal recessive disease that currently limits the average life expectancy of sufferers to &#60;40 years of age. The development of novel drug molecules to restore the activity of CFTR is an important goal in the treatment CF, and the isolation of functionally active CFTR is a useful step towards achieving this goal.
We describe two methods for the purification of CFTR from a eukaryotic heterologous expression system, S. cerevisiae. Like prokaryotic systems, S. cerevisiae can be rapidly grown in the lab at low cost, but can also traffic and posttranslationally modify large membrane proteins. The selection of detergents for solubilization and purification is a critical step in the purification of any membrane protein. Having screened for the solubility of CFTR in several detergents, we have chosen two contrasting detergents for use in the purification that allow the final CFTR preparation to be tailored to the subsequently planned experiments.
In this method, we provide comparison of the purification of CFTR in dodecyl-&#946;-D-maltoside (DDM) and 1-tetradecanoyl-sn-glycero-3-phospho-(1&#39;-rac-glycerol) (LPG-14). Protein purified in DDM by this method shows ATPase activity in functional assays. Protein purified in LPG-14 shows high purity and yield, can be employed to study post-translational modifications, and can be used for structural methods such as small-angle X-ray scattering and electron microscopy. However it displays significantly lower ATPase activity.

Purification of the Cystic Fibrosis Transmembrane Conductance Regulator Protein Expressed in Saccharomyces cerevisiae

Heterologous expression and purification of the cystic fibrosis transmembrane conductance regulator (CFTR) are significant challenges and limiting factors in the development of drug therapies for cystic fibrosis. This protocol describes two methods for the isolation of milligram quantities of CFTR suitable for functional and structural studies.&#160;

Defects in the cystic fibrosis transmembrane conductance regulator (CFTR) protein cause cystic fibrosis (CF), an autosomal recessive disease that ...

Probing High-density Functional Protein Microarrays to Detect Protein-protein Interactions

High-density functional protein microarrays containing ~4,200 recombinant yeast proteins are examined for kinase protein-protein interactions using an affinity purified yeast kinase fusion protein containing a V5-epitope tag for read-out. Purified kinase is obtained through culture of a yeast strain optimized for high copy protein production harboring a plasmid containing a Kinase-V5 fusion construct under a GAL inducible promoter. The yeast is grown in restrictive media with a neutral carbon source for 6 hr followed by induction with 2% galactose. Next, the culture is harvested and kinase is purified using standard affinity chromatographic techniques to obtain a highly purified protein kinase for use in the assay. The purified kinase is diluted with kinase buffer to an appropriate range for the assay and the protein microarrays are blocked prior to hybridization with the protein microarray. After the hybridization, the arrays are probed with monoclonal V5 antibody to identify proteins bound by the kinase-V5 protein. Finally, the arrays are scanned using a standard microarray scanner, and data is extracted for downstream informatics analysis1,2 to determine a high confidence set of protein interactions for downstream validation in vivo.

Using protein microarrays containing nearly the entire S. cerevisiae proteome is probed for rapid unbiased interrogation of thousands of protein-protein interactions in parallel. This method can be utilized for protein-small molecule, posttranslational modification, and other assays in high-throughput.

High-density functional protein microarrays containing ~4,200 recombinant yeast proteins are examined for kinase protein-protein interactions using an ...

Cardiac Pressure-Volume Loop Analysis Using Conductance Catheters in Mice

Cardiac pressure-volume loop analysis is the &#8220;gold-standard&#8221; in the assessment of load-dependent and load-independent measures of ventricular systolic and diastolic function. Measures of ventricular contractility and compliance are obtained through examination of cardiac response to changes in afterload and preload. These techniques were originally developed nearly three decades ago to measure cardiac function in large mammals and humans. The application of these analyses to small mammals, such as mice, has been accomplished through the optimization of microsurgical techniques and creation of conductance catheters. Conductance catheters allow for estimation of the blood pool by exploiting the relationship between electrical conductance and volume. When properly performed, these techniques allow for testing of cardiac function in genetic mutant mouse models or in drug treatment studies. The accuracy and precision of these studies are dependent on careful attention to the calibration of instruments, systematic conduct of hemodynamic measurements and data analyses. We will review the methods of conducting pressure-volume loop experiments using a conductance catheter in mice.

Cardiac pressure-volume loop analysis is the most comprehensive way to measure cardiac function in the intact heart. We describe a technique to perform and analyze cardiac pressure volume loops, using conductance catheters.

Cardiac pressure-volume loop analysis is the &#8220;gold-standard&#8221; in the assessment of load-dependent and load-independent measures of ventricular ...

Fish Sperm Assessment Using Software and Cooling Devices

For gamete quality evaluation, there are innovative, rapid, and quantitative techniques that can provide useful data for aquaculture. Computerized systems for sperm analysis were developed to measure several parameters and one of the most commonly measured is the sperm motility.
Initially, this computer technology was designed for mammalian species, although it can also be used for fish sperm analysis. Fish have specific features that can affect sperm assessment such as a short motility time after activation and, in some cases, adaptation to lower temperatures. Thus, it is necessary to modify both software and hardware components to make motility analysis more efficient for fish sperm analysis. For mammalian sperm, the heating plate is used to maintain optimal temperatures of spermatozoa. However, for some fish species, it is advantageous to use a lower temperature to prolong the duration of motility, since the sperm remain active for less than 2 min. Therefore, cooling devices are necessary to refrigerate samples at constant temperature over the time of analysis, including on the optical microscope. This protocol describes the analysis of fish sperm motility using software for sperm analysis and new cooling devices to optimize the results.

The present protocol describes a procedure of fish sperm assessment using computer-assisted sperm analysis and cooling devices. The software gives a rapid, accurate and quantitative analysis of fish sperm quality based on spermatozoa motility, which can be a useful tool in aquaculture to improve reproduction success.

For gamete quality evaluation, there are innovative, rapid, and quantitative techniques that can provide useful data for aquaculture. Computerized systems ...